JP2023536275A - Systems and methods for charging and discharging electrochemical devices - Google Patents

Abstract

A system and method for charging a battery using a signal of a frequency or harmonic content having at least one harmonically adjusted shape based on the impedance of the battery. The system may further include a power converter operable to coordinate charging and powering the load. In some cases, an output signal is generated in which the charging signal is interleaved. Additionally, the output signal may be adjusted based on the output impedance to the discharge signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This PCT (Patent Cooperation Treaty) application is related to U.S. Patent Application No. 63/059,044, entitled "Systems and Methods for Electrochemical Device Charging and Discharging," filed July 30, 2020, Its priority is claimed and its entire contents are incorporated herein by reference. This application is also related to co-pending U.S. patent application Ser. Cited in the book.

Embodiments of the present invention relate generally to systems and methods for charging batteries, and more particularly to systems and methods for generating high efficiency and/or fast charging signals for charging batteries.

Many electrically powered devices such as power tools, vacuum cleaners, any number of different portable electronic devices, and electric vehicles use rechargeable batteries as a source of operating power. Rechargeable batteries are constrained by a finite battery capacity and must be recharged when exhausted. Recharging the battery can be inconvenient because it often requires the electric machine to be stopped for the required time. For vehicles, recharging can take several hours. For this reason, great efforts have been made to develop fast charging techniques that reduce the time required to recharge the battery. However, fast recharging systems are typically less efficient, while slow recharging systems result in longer recharging operations, defeating the primary purpose of fast availability.

At perhaps the simplest level, charging a battery involves passing a DC charging current through the battery, as shown in FIG. 1A. However, various types of batteries have a limited current that can be accepted before the battery is damaged. FIG. 1A is a schematic diagram of a simple circuit 100 for recharging a single cell battery. Other components of the circuit, such as ammeters, voltmeters, controllers, etc., are not shown. Battery 104 may be recharged by application of a recharge power signal from controllable power source 102 . Various embodiments involving charging and discharging as discussed herein are applicable to electrochemical devices such as batteries. The term "battery" in the art can be used variously to include individual cells having anodes and cathodes separated by an electrolyte, as well as collections of such cells connected in various configurations. can be expressed A battery generally includes repeating units of a countercharge source and a first electrode layer separated by an ionically conductive barrier, often a liquid or polymer membrane saturated with electrolyte. Because these layers are constructed thin, multiple units may occupy the battery volume, increasing the available battery power for each stacked unit. Although many examples are discussed herein as applicable to batteries, cells, or battery cells, it should be appreciated that the systems and methods described can be applied to many different types of cells, as well as parallel , series, and series-parallel coupled cells with different possible interconnections of cells. For example, the systems and methods discussed herein may also apply to battery packs containing multiple cells configured to provide specified pack voltages, output currents, and/or capacities. Further, the embodiments discussed herein can be used, by way of example, with various different types of lithium batteries (including but not limited to lithium metal batteries and lithium ion batteries), lead-acid batteries, various types of nickel batteries, and different types of electrochemical devices such as solid state batteries. The various implementations discussed herein may also apply to battery configurations of different constructions, such as button or "coin" type batteries, cylindrical cells, pouch cells, and prismatic cells. Application of a power signal to the electrodes of battery 104 causes electrons to flow back through the battery, thereby replenishing the stored concentration of charge carriers (such as lithium ions) at the anode. In one particular example, power source 102 may be a direct current (DC) voltage source that provides DC charging current to battery cells 104 . Also, different types of power sources may be used, such as controlled current sources.

Pulsed charging has been considered in some fast charging scenarios. FIG. 1B shows a graph 110 of a prior art DC voltage signal 122 generated by the power supply 102 and applied to the battery cell 104 to recharge the battery. The graph shows input voltage 112 versus time 114 for charging signal 122 . Generally, the power source 102 can be controlled to supply repetitive pulses 122 to the electrodes of the battery cell 104 to recharge the battery cell. In particular, power supply 102 may be controlled to provide a repeating square wave (shown as pulse 116 followed by pulse 118 ) signal to battery cell 104 . The peaks of the square wave pulses 116 , 118 may be below the voltage threshold 120 corresponding to the operating constraints of the voltage source 102 . A normal charging signal used to recharge the battery cells 104 may cause the charging signal to be applied during the charging period, with a rest period of some duration between the application of the charging signal. do. Such operation of circuit 100 produces recharge signal 122 in a repeating square wave pattern, as shown in FIG. 1B.

However, in some cases, recharging the battery cells 104 by applying the square wave charge signal 122 may shorten the life of the battery cells being recharged or may reduce the efficiency of recharging the battery. . For example, a sudden application of charging current (ie, sharp leading edge 124 of square wave pulse 116) to the electrode (usually the anode) of battery cell 104 can also create a large initial impedance across the battery terminals. In particular, FIG. 1C illustrates a graph of estimated real impedance values of battery cell 104 versus corresponding frequency of the recharge signal applied to battery cell 104, according to one embodiment. In particular, graph 150 shows a plot of real impedance values (axis 154) versus the frequency of the input signal to battery cell 104 on a log frequency axis (axis 152). Plot 150 shows real impedance values between the electrodes of battery cell 104 at different frequencies of the recharge power signal used to recharge the battery. The shape and measurements of plot 150 may vary based on battery type, battery state of charge, battery operating constraints, battery heat, and the like. However, the characteristics of the battery during charging can be generally understood from plot 158 . In particular, the real impedance value at the electrodes of the battery cell 104 may vary based on the frequency of the charging signal supplied to the battery, and generally sharp increases in the real impedance value 328 may occur at higher frequencies. For example, an input power signal to battery cell 104 at frequency f _Sq 162 may induce a high real impedance 160 across the electrodes of battery cell 104 .

Referring again to the square wave charging signal 122 of FIG. 1B, there may be large frequency signals at the corners of the square wave pulse 116 . In particular, rapid changes in the charge signal to the battery cell 104 (such as the leading edge 124 of pulse 116) can cause the leading edge of the square wave pulse, the trailing edge of the square wave pulse, and when using the conventional inverse pulse scheme, etc. Noise consisting of high frequency harmonics may also be introduced. As shown in graph 150 of FIG. 1C, such harmonics create a large impedance across the electrodes of the battery. Such high impedance can lead to capacity loss, heat generation, and electrokinetic imbalance across the battery cell, undesirable electrochemical response at the charge boundary, and damage to the battery, shortening battery cell life. Many inefficiencies can result, such as degradation of materials within the battery cells 104 . Furthermore, the cold start of the battery with fast pulses initiates the capacitive charging and diffusion process, thus limiting the faradaic effect. During this time, the proximal lithium reacts and is immediately consumed, leaving periods of unwanted side reactions and diffusion-limited conditions that adversely affect the condition of the cell and its components. These and other inefficiencies are particularly detrimental in fast recharging of battery cells 104, which often involve relatively large currents.

With these observations, among others, in mind, various aspects of the present disclosure have been devised and developed.

Aspects of the present disclosure include a charging system with a charging signal shaping circuit. The system is in operable communication with a charge signal shaping circuit to shape the charge signal to define a charge signal for the electrochemical device based on harmonics associated with values representative of current flow to the electrochemical device. A controller that controls the circuit is further provided. The system further comprises a power converter operably coupled with the electrochemical device to supply power to the load.

In another aspect, the power converter is in operable communication with the controller. A controller is configured to control the power converter to generate a discharge waveform from the electrochemical device based on harmonics associated with values representing current flow from the electrochemical device. In another aspect, the charge signal comprises a series of regulated charge pulses, the discharge signal comprises a series of regulated discharge pulses, and the controller interleaves the series of regulated charge pulses with the series of regulated discharge pulses. to control the charge signal shaping circuit and the power converter.

These and other aspects of the disclosure are described in more detail below.

1 is a schematic diagram of a conventional circuit for charging a battery; FIG. 1 is a signal diagram of a prior art DC voltage or current signal for recharging a battery; FIG. 4 is a graph of estimated real impedance values of a battery versus corresponding frequencies of a charging signal applied to the battery, according to one embodiment. FIG. 2 is a schematic diagram illustrating a circuit for charging a battery using charging signal shaping circuitry, according to one embodiment. 4 is a graph of a sinusoidal cell charging signal having a frequency corresponding to a determined minimum real impedance value of a battery cell, according to one embodiment; 4 is a graph of measured real impedance values of a battery versus corresponding frequencies of a charging signal applied to a battery cell, according to one embodiment. FIG. 4 is a schematic diagram illustrating a circuit for shaping a battery charge signal based on the frequency corresponding to the minimum impedance value, according to one embodiment. [0012] Figure 4 is a flow chart illustrating a method for generating a battery charging signal based on a frequency corresponding to a minimum impedance value, according to one embodiment. 4 is a plot of superimposed square and sinusoidal pulses of a battery charging signal, according to one embodiment. FIG. 4 is a graph of measured real impedance values of a battery versus corresponding frequencies of a charging signal applied to the battery at specified maximum and minimum frequencies, according to one embodiment. FIG. 4 is a signal diagram of a shaped battery charge pulse having multiple frequencies corresponding to the highest and lowest frequency real impedance values within an allowable range based on the displayed impedance of the battery cell, according to one embodiment. 1 is a flowchart illustrating a method for generating a battery charge signal based on a range of frequencies corresponding to maximum and minimum real impedance values of battery cells, according to one embodiment. FIG. 4 is a signal diagram of a first shaped charging pulse train generated from a battery charging circuit, according to one embodiment. FIG. 4 is a signal diagram of a second shaped charging pulse train generated from a battery charging circuit, according to one embodiment. FIG. 4 is a signal diagram of a charge signal showing real and imaginary impedance values of a battery as applied to the battery over time, according to one embodiment. 4 is a graph of measured real, imaginary, and nominal impedance values of a battery cell versus corresponding frequencies of a charging signal applied to the battery cell, according to one embodiment. FIG. 4 is a signal diagram of a shaped battery cell charging signal including a leading edge portion and a body portion generated from a battery charging circuit, according to one embodiment. 4 is a plot of measured voltage drop and measured current across a battery during battery charging in response to a charging signal applied to the battery, according to one embodiment. 4 is a plot of measured voltage drop and measured current across a battery during battery charging in response to a charging signal applied to the battery, according to one embodiment. 4 is a plot of measured current and voltage across a current sensing resistor in a battery in response to a charging signal applied to the battery versus time, according to one embodiment. 1 illustrates an example computer system that can be used to implement embodiments of the present disclosure; FIG. 1 is a diagram of a circuit for defining a charging signal and providing a power conversion function to power a load while charging a battery of the load, in one example; FIG. 1 is a diagram of a circuit for defining a charging signal and providing a step-down function to power a load while charging the battery of the load, in one example; FIG. 1 is a diagram of a circuit for defining a charge signal and providing a boost function to power a load while charging the battery of the load, in one example. FIG. Figure 16 shows an example of a harmonically adjusted charge pulse generated by a control signal applied to the circuit of Figure 15; 18B illustrates an example control pulse of a control signal that, upon application to the circuit of FIG. 15, produces the harmonically adjusted charging signal of FIG. 18A. FIG. FIG. 16 illustrates an example control pulse for driving a charge shaping power converter, such as through the circuit shown in FIG. 15, in one example; FIG. 3 shows an example of a PWM signal for driving a buck or boost power converter; 19D shows an example of a harmonic shaped output current waveform generated from a duty cycle such as that shown in FIG. 19D, in one example; FIG. FIG. 4 illustrates an example of changing the duty cycle of a buck or boost power converter to shape the discharge pulse according to harmonics with an initial short on-cycle transition to a long on-cycle in one example. FIG. 4 is a diagram showing an example of a charging signal shaping circuit including a parallel booster circuit; FIG. 4 is a diagram showing an example of a charging signal shaping circuit including a parallel step-down circuit in one example; FIG. 4 is a diagram showing an example of a charging signal shaping circuit including a parallel booster circuit; FIG. 4 is a diagram showing an example of a charging signal shaping circuit including a parallel step-down circuit in one example;

Disclosed herein are systems, circuits, and methods for battery charging (recharging) and battery discharging. The terms charging and recharging are used synonymously herein. The systems, circuits, and methods discussed herein allow energy to be charged to or discharged from a battery more efficiently than conventional charging circuits and methods. As discussed herein, energy efficiency as well as a number of other benefits are realized alone or in combination with efficiency. For example, the charging and/or discharging techniques described herein can reduce the rate at which the anode is damaged, can reduce the heat generated during charging or discharging (or can provide a way to control the heating). ), which can provide multiple benefits such as reduced anode and cell damage, reduced risk of fire or short circuit. In other examples, the charging techniques described herein may enable faster charging by applying high charging rates to the cells. Over what is considered a standard charge or discharge rate, the techniques described herein can relatively improve cycle depth and/or cycle life. In one example, during periods of what are considered "slow charging" of the battery, the disclosed systems and methods provide longer battery life and charging energy efficiency. In another example, during what is considered a "fast charge" period, the disclosed systems and methods improve the balance between charge rate and battery life while reducing heat generation. Conventional charging circuits have focused on the electronic device of the charging circuit to address the efficiency of the charging circuit. Provides a battery charging signal.

In one example, in various embodiments discussed herein, one or more energy transfer associated with optimal energy transfer to and/or from a battery cell based on real and/or imaginary values of energy transfer. The battery is charged and/or discharged by generating pulses of a charge or discharge signal corresponding to the frequency (which may be one or more harmonics). In one example, the frequency may be associated with the minimum real impedance value of the battery. In another example, the pulses of the charging signal correspond to harmonics associated with both real and imaginary impedance values of the battery. In yet another example, the pulses of the charge signal may correspond to harmonics associated with one or both of the conductance or susceptance of the battery cell's admittance. More particularly, systems and circuits are described that determine the frequency corresponding to the minimum impedance value. In some instances, the frequency of minimum impedance can change with state of charge, temperature, and other factors, so the techniques discussed herein allow the minimum impedance frequency to be re-evaluated. These circuits can shape or generate pulses of charging signals (eg, charging current) that correspond to harmonics or frequencies associated with the minimum impedance. As introduced above, changes in the material properties, chemical processes, and electrochemical processes within the battery can change the frequency corresponding to the minimum impedance value due to variations in the state of charge and temperature during recharge and discharge. Accordingly, the circuit may optionally perform an iterative process of monitoring or determining the frequency corresponding to the minimum impedance value of the battery and adjusting the charging pulses to and/or discharging pulses from the battery. This iterative process can improve the efficiency of the charge or discharge signal, thus reducing battery recharge time, extending battery life (e.g., increasing the number of charge/discharge cycles that can be performed, among other benefits). ), optimizing the amount of current to or from the battery and avoiding energy loss due to various inefficiencies.

To generate charge pulses with appropriate harmonic content, the battery recharge circuit includes one or more charge pulse shaping circuits, impedance measurement circuits (including both hardware and/or software components), and/or or may include an application specific integrated circuit. In one particular embodiment, the charge pulse shaping circuit may include a filter circuit controllable by the pulse control signal. A filter circuit may prevent fast changes in the charging pulses sent to the battery cells. In particular, the filter circuit may shape the input current square wave based on Z=jωL such that current flow is restricted at high frequencies and current can flow through the circuit at low frequencies. Selection of Filter Circuit Components Can Shape Leading Edges of Charge Pulses to Maximize Power Delivered to Battery Cells While Limiting Inefficient Harmonics Present in Traditional Square-Wave Power Signals is. Also, the pulse control signal to the filter circuit can set the duration of each frequency adjusted charging pulse delivered to the battery cell. Also, the charging signal shaping circuit may include a current shaping circuit that is controllable by a current shaping control signal. In one embodiment, the current shaping circuit may modify the magnitude of the charge pulse by removing or extracting current from the pulse prior to applying the charge pulse to the battery cell. The shaper may also be responsible for defining the trailing edge of the pulse, the pulse duration, the voltage level between pulses, and other functions.

The systems, circuits, and methods disclosed herein utilize multiple batteries connected in any way to achieve the desired capacity, voltage, and output current range for any application in which the battery cells and batteries are used. It is applicable to charging any form of battery that may have 1 cell. Various embodiments discussed herein are also believed to enable fast charging. In one or both situations, the circuit may be controlled to provide a recharge pulse that includes a shaped rising leading edge rather than the sharp edges associated with conventional square waves. In one example, the rising leading edge of the charging pulse may be based on a determined frequency (harmonic) corresponding to the harmonic associated with the minimum or near minimum real impedance value of the battery cell. The charge pulse may also be based on a combination of minimum real and imaginary impedances of the cell to be charged. In another example, the charge pulse may be based on the conductance and/or susceptance of the battery cell being charged, or any other admittance factor alone or in combination. Still other embodiments of battery cells are conceivable, and these can be used to shape charging pulses. Generally speaking, when real and imaginary impedance values are considered, the technique evaluates the values of harmonics that alone or in combination result in relatively low impedances. In these techniques, an admittance evaluates harmonics whose conductance and susceptance, alone or in combination, are relatively high.

Now discussing pulses based on real impedance minimum values, inefficient or detrimental high-order harmonic content in the charge signal can be eliminated by applying a rising leading edge corresponding to approximately the minimum real impedance value. Additionally, exceeding one or more upper thresholds of the magnitude of the charge pulse maximizes the amount of power applied to the battery in the pulse without, among other things, damaging the battery and affecting its capacity or life. The duration of the charging pulse may be controlled by the circuit so as to reduce or increase the charge pulse. These pulse-shaped charging signals are applied under the control of the circuit so that in each pulse an optimized amount of power is delivered to the battery while at the same time the high frequency harmonics that cause degradation are signaled. may be removed from Such shaped charging signals can improve the efficiency and speed of recharging the battery cells by reducing the impedance across various interfaces within the battery, including the electrodes, as the battery cells are being charged.

FIG. 2 is a schematic diagram illustrating a circuit 200 for recharging a battery cell 204 utilizing a charge pulse shaping circuit 206 and an impedance measurement circuit 208, according to one embodiment. Generally, circuit 200 may include power supply 202, which may be a voltage source or a current source. In one particular embodiment, power supply 202 is a direct current (DC) voltage source, although the use of alternating current (AC) sources is also contemplated. More specifically, the power supply 202 can be a DC power supply that provides unidirectional current, an AC power supply that provides bidirectional current, or a power supply that provides ripple current (such as an AC signal with a DC bias to make the current unidirectional). may contain In general, the power supply 202 provides a charging current that is shaped and usable to charge the battery cells 204 . In one particular implementation, circuit 200 of FIG. 2 may include charging signal shaping circuitry 206 that shapes one or more pulses of the charging signal for use in charging battery cells 204 . In one example, circuit controller 210 may provide one or more inputs to charge signal shaping circuit 206 to control shaping of the charge signal. These inputs may be used by shaping circuit 206 to change the signal from power source 202 into a more efficient charging signal for battery cell 204 . The operation and configuration of charging signal shaping circuit 206 is described in greater detail below.

In some cases, charging signal shaping circuit 206 modifies energy from power source 202 to produce charging pulses that correspond, at least in part, to harmonics associated with the lowest real impedance value of battery cell 204. good. Alternatively, directly measure the impedance by characterizing the cell so that the impedance can be known at any given charge current, voltage level, charge level, charge/discharge cycle number, and/or temperature, among other factors. Alternatively, a search from memory or the like may be performed. In one example, the circuit 200 is connected to the battery cell 204 to measure cell voltage and charging current, as well as other cell characteristics such as temperature, and an impedance measurement circuit that measures or calculates the impedance between the electrodes of the cell 204. 208 may be included. In one example, impedance may be measured based on applied pulses. Impedance is also measured as part of a routine to characterize the cell by applying different frequency characteristic signals to generate a range of impedance values associated with different frequency characteristics of the cell. This may be done before, during and periodically during charging, and may be used in combination with search and other techniques. Cell impedance can include real and imaginary or reactance values. The impedance of a battery cell 204 can change based on many physical or chemical characteristics of the cell, such as the cell's state of charge and/or temperature. Thus, the control of the impedance measurement circuit 208 by the circuit controller 210 determines, among other things, various impedance values of the battery cell 204 when the cell is recharging, and outputs the measured impedance values to the circuit controller 210 . may be provided to In some cases, the circuit controller measures the battery cell 204 so that the energy from the power source 202 can be transformed into one or more charging pulses corresponding to harmonics associated with the lowest real impedance value of the battery cell 204. A real component of the impedance may be provided to the charge signal shaping circuit 206 . In another example, circuit controller 210 may generate one or more control signals based on the received real impedance values and provide these control signals to charge signal shaping circuit 206 . The control signal may, among other functions, shape the charge pulse to include harmonic components corresponding to real impedance values. In yet another example, the charging signal shaping circuit 206 modifies the energy from the power source 202 to be associated with the conductance or susceptance component of the admittance of the battery cell 204 or any other factor related to the impedance of the battery cell. A charging pulse may be generated that at least partially corresponds to the harmonic. Thus, although described herein as relating to the real or imaginary component of impedance, these systems and methods similarly measure or measure other characteristics of the battery cell, such as the conductance or susceptance components of the admittance of the battery cell. can be considered.

FIG. 3A is a graph 302 of an example sinusoidal charging signal having a frequency corresponding to the determined minimum real impedance value of battery cell 204 that may be generated by circuit 200 of FIG. In this example, the frequency of the sinusoidal signal itself is the frequency corresponding to the lowest real impedance of the battery cell to be charged. More specifically, graph 302 shows plot 314 of input voltage axis 304 versus time axis 306 of the charging signal delivered to battery cell 204 . In contrast to the square wave charging signals described above, the charging signals generated by circuit 200 may include repetitive sinusoidal charging signals delivered to battery cells 204 . Although only two pulses (pulses 308, 310) are shown in FIG. 3A, it will be appreciated that such a pulse train can be delivered to the battery cell for a period of time sufficient to charge the battery cell to a certain level. shall be It is believed that the frequency of the sine wave can and does change over time depending on the impedance of the battery cell and the control scheme implemented. As discussed herein, the frequencies of the shaped pulses and sine waves are set to a minimum impedance or near a minimum impedance (above the minimum impedance, below the minimum impedance, or both), depending on the implementation. good too. Therefore, the frequency need not be strictly set to the minimum impedance. The sinusoidal pulses 308 , 310 of the charging signal 314 may continue to be generated and delivered to the battery cells 204 during recharging operations of the circuit 200 . The sinusoidal nature of charging signal 314 may reduce the impedance at battery cell 204 and improve the efficiency of the recharging operation because the high frequency noise component normally present in charging signals with a square wave profile is removed. The charging signal 314 may also include a subsidence or depolarization period 316 of some duration between the pulses 308,310. The duration of the settling period 316 may be adjustable or controllable by the circuit controller 210 and may be based on various aspects of the recharging behavior of the battery cells 204, depending on past pulses 308 of the charge signal 314. The total power delivered, the state of charge of the battery cell 204, the measured or estimated temperature of the battery cell 204, the measured impedance of the battery cell 204, and/or the hardware components used in the charging circuit. not. For example, the duration of settling period 316 is based on the processing speed of circuit controller 210 to allow adequate time for control circuit 210 to determine one or more target values for control of charging circuit 200 . may Also, the magnitude of the pulses 308 , 310 may be below the voltage threshold 312 . The voltage threshold 312 is based on multiple factors of the battery cell 204 and/or the power source 202, such as the upper voltage or current threshold of the power source and/or thermodynamic boundaries associated with the voltage, temperature, and current of the battery cell 204. may In some cases, voltage threshold 312 may be controlled by circuit controller 210, as described in more detail below.

In one particular example, the frequency or harmonics of the sinusoidal pulses 308 of the charge signal 314 generated by the circuit 200 to recharge the battery cells 204 are selected by the circuit controller 210 and applied to the charge pulses to cause the battery cells 204 may be such that the impedance at is minimized. For example, FIG. 3B is a graph 322 of measured real impedance values of battery cell 204 versus corresponding frequencies of a charging signal applied to the battery cell, according to one embodiment. In particular, graph 322 shows a plot of real impedance values (axis 324) versus the logarithmic frequency axis of the charging signal (axis 326). Plot 328 shows real impedance values between the electrodes of battery cell 204 at different frequencies of the sinusoidal charging signal. As shown, the real impedance value 328 may vary based on the frequency of the charging signal, typically with the highest frequency causing the real impedance value 328 to rise rapidly. However, plot 334 of real impedance values for battery cell 204 also shows minimum real impedance value 330 corresponding to a particular charging signal frequency labeled f _Min . A plot of the real impedance value 334 of the battery cell 204 may depend on many factors of the cell, such as battery chemistry, state of charge, temperature, charge signal configuration, and so on. Thus, the frequency f _Min 332 corresponding to the minimum real impedance value 330 of the battery cell 204 may similarly depend on the characteristics of the particular battery cell 204 being charged. Frequency f _Min 332 may correspond to other elements of battery cells 204, such as the configuration of the cells in the pack and the connections between cells in the pack.

Generate sinusoidal charging pulses 308, 310 at or near a frequency 332 corresponding to the minimum real impedance value 330 of the battery cell 204 due to potential inefficiencies such as the impedance of the battery cell 204 converting received power into heat. This may improve the efficiency of applying charging energy to battery cells 204 . In other words, by shaping the pulses 308, 310 of the charging signal 314 to include harmonics at or near frequency f _Min 332, less wasted energy is converted to heat by the impedance of the battery cell 204, resulting in less battery power. The efficiency of charging signal 314 to cell 204 may be improved. Thus, one embodiment of the recharging circuit 200 of FIG. 2 includes an impedance measurement circuit 208 coupled to the battery cell 204 that determines various real impedance values of the battery cell over a range of frequencies of the charging signal. good too. Impedance measurement circuitry 208 may include any known or hereafter developed circuitry configured to measure impedance between electrodes of battery cell 204, such as voltage and current sensors. A plurality of impedance values of the battery cell 204 are measured at different frequencies of the charging power signal and provided to the circuit controller 210 to determine or estimate the minimum real impedance value of the curve 334 of the battery cell 204. may The circuit controller 210 also directs one of the charging signal shaping circuits 206 to generate a series of sinusoidal charging pulses 308, 310 at harmonics of a frequency f _Min 332 corresponding to the minimum real impedance value 330 of the battery cell 204. Alternatively, multiple components may be controlled. Also, as will be described in more detail below, the circuit controller 210 performs an iterative process of measuring or determining an estimated real impedance value for the current state of the battery cell 204 at various times during the recharging session, The pulses 308 , 310 of the charge power signal 314 may be adjusted accordingly to match the new estimated frequency f _Min 332 . By controlling the circuit 200 to generate a charging signal 314 having harmonic frequencies of the pulses 308, 310 based on the determined or estimated minimum real impedance value, the high impedance at the electrodes due to the high frequency portion of the charging signal The energy of charge signal 314 may be applied more efficiently to recharge battery cells 204 while minimizing wasted energy.

One particular implementation of a circuit for charging a battery cell using charge pulse shaping is shown in FIG. The circuit 400 may be controlled by the controller 210 to shape the battery cell recharge signal based on the frequency f _Min corresponding to the minimum impedance value. In one example, controller 210 may be a feedback control system using voltage or current amplifiers. In general, controller 210 may be an analog controller, digital controller, microcontroller, or microprocessor, or a customized integrated circuit such as an application specific integrated circuit (ASIC). Controller 210 may be configured or programmed to perform one or more of the operations for controlling execution of shaping circuit 400 discussed herein. Additionally, as discussed below, circuit 400 may consider the imaginary component of impedance, the conductance component of admittance, the susceptance component of admittance, or any combination thereof. More or fewer components may be included in circuit 400 and may be replaced by other components of equivalent function. In some embodiments, several components are replicated in parallel to charge multiple cells in parallel or to provide greater charging capacity for a given cell or configuration of cells. may have been Circuit 400 of FIG. 4 is just one example of a power signal shaping circuit that can be controlled to provide the harmonic sinusoidal charging signals discussed herein.

Circuit 400 may include power supply 402 coupled to rail 442 to provide charging signals to battery cells 404 . Power source 402 can be any type of energy source, such as a DC voltage source, an AC voltage source, a current source, or the like. In some embodiments, power supply 402 may change the waveform or pulse magnitude of the energy supplied to circuit 400 under control via an input (V _CONT 434 ). For example, circuit controller 210 may provide control signal V _CONT 434 to power supply 402 to turn on the power supply, select the magnitude of the power signal, select between a DC power signal and an AC power signal, etc. good. In one particular example, power supply 402 may be configured to adjust the magnitude of the charging signal it provides based on the voltage value of the received V _CONT 434 signal.

Filter circuit 406 may be coupled to power rail 442 to receive power generated by power supply 402 . Filter circuit 406 may generally include components that output a charging signal having a portion corresponding to frequency f _Min 322 to battery cell 404 . For example, the output signal from filter circuit 406 may include leading edges of harmonics at or near frequency f _Min 322 corresponding to the minimum real impedance value determined above. In some cases, the components of filter circuit 406 can be controlled by one or more pulse control signals 416 sent to filter circuit 406 by circuit controller 210 . In the particular example shown in FIG. 4, filter circuit 406 may comprise a first inductor 410 connected in series between power supply rail 442 and first transistor 412 . The selection of the inductor value may depend, among other things, on the charging characteristics of the battery cell 404, since the inductor value of the first inductor 410 affects the shape of the leading edge of the pulse. The first transistor 412 may also be connected to the first electrode of the battery cell 404 . A first transistor 412 may receive an input signal, such as a pulse control signal 416, and operate as a switching device or component. Generally, the first transistor 412 can be any kind of FET transistor or any kind of controllable switch for connecting the first inductor 410 to the first electrode 440 of the battery cell 404 . may be For example, first transistor 412 may be a FET transistor having drain 412 connected to first inductor 410 , source connected to battery cell 404 , and gate receiving pulse control signal 416 . In one embodiment, the pulse control signal 416 is provided by the circuit controller 210 to connect the node 436 to the first electrode of the battery cell 404 when closed and disconnect the connection between the inductor 410 and the battery cell 404 when opened. A switch may be used to control the operation of the first transistor 412 . The control of the first transistor 412 to generate the charging pulses is described in more detail below with reference to the method 500 of FIG.

First inductor 410 may generally operate to prevent a rapid increase in current sent to battery cell 404 upon connection to battery cell 404 via first transistor 412 . More specifically, the first inductor 410 may resist rapid conduction of current through the inductor to the battery cell 404 (when the first transistor 412 is conducting). This resistance to rapid current build-up prevents the pulse of the charge signal supplied by power supply rail 442 from having a sharp leading edge and suppresses high frequency harmonics that can occur in battery cell 404 when a square wave input is applied. . Current or other form of energy flux from power supply rail 442 flows through first inductor 410 and first transistor 412 to the battery when it becomes conductive in response to a signal on pulse control signal input 416 to transistor 412 . It can be supplied to the cell 404 to charge the battery cell 404 while minimizing the effects of high frequency noise. Filter circuit 406 may also optionally include a flyback diode 414 connected in parallel with first inductor 410 . Flyback diode 414 provides a return path for energy flux supplied by power rail 442 when first transistor switch 412 is open or non-conducting. For example, first transistor 412 may be controlled by pulse control signal 416 to stop conducting current from power rail 442 to battery electrode 440 . Current can then be returned to the upper rail 442 through the flyback diode 414 . A storage capacitor 432 is also connected between the upper rail 442 and ground or common so that the current supplied by the power rail 442 and returned through the flyback diode 414 is reduced during the open period of the first transistor 412 . may also be supplied to the storage capacitor 432 via the upper rail 442 . As will be explained in more detail below, upon closure of the first transistor 412 (such as the next pulse of the charge signal), the energy stored in the storage capacitor 432 is returned to the upper rail 442 and the input of the filter circuit 406, thereby The efficiency of the circuit 400 may be further improved by ensuring that no energy is lost in the circuit 400 during the open period of the one transistor 412 .

Although FIG. 4 shows the components of a single filter circuit 406 , additional filter circuits of the same or similar configuration may be connected in parallel with filter circuit 406 . For example, filter circuit 406 and any number of additional filter circuits (up to filter circuit N 418 ) may be connected in parallel in charging circuit 400 . Each filter circuit 406, 418 is independently controlled by the circuit controller 210 by a respective pulse control signal 406 to remove one or more harmonics from the current supplied for charging the battery cell 404. It can be like this. In another example, the same pulse control signal 416 may control more than one filter circuit 406 . One or more of the additional filter circuits 418 may have similar components with the same or different values. For example, the first inductor of filter circuit N 418 may have a larger inductance value than the first inductor 410 of filter circuit 406 . In general, a large inductance value of the first inductor 410 increases the resistance to rapid changes in the charge pulse, and therefore slopes the leading edge of the charge pulse for a small value inductor. Thus, the circuit controller 210 shapes the leading edge of the energy pulse supplied to the battery cell 404 by controlling the various filter circuits 406, 418 with various inductance values of the selected first inductor 410. You may do so.

One or more input shaping circuits 420 may be connected to the first electrode 440 (eg, anode or positive terminal) of the battery cell 404 to further modify the pulses of the charging signal supplied to the battery cell 404. good. In particular, the input shaping circuit 420 may comprise a second inductor 424 connected between the first electrode 440 of the battery cell 404 and the second transistor 422 . In one example, the second transistor 422 may be a FET transistor with a drain 444 connected to the second inductor 424 , a source 446 connected to ground or common, and a gate receiving the control signal 426 . Similar to the first transistor 412, the second transistor 422 may be adapted to act as a switch connecting the source 444 to the drain 446 which is connected to the negative rail, ground, or common. A second transistor 422 may be controlled by an input control signal 426 . In one embodiment, shaped input signal 426 may be a high frequency pulse width modulated (PWM) signal that alternates between on and off states at high frequencies. In one example, PWM signal 426 operates at a frequency greater than 100 kHz, although PWM signal 426 may operate at any frequency. In response to a high frequency switching PWM signal 426, the second transistor 422 is adapted to rapidly alternate between a conducting state (or "on" state) and a non-conducting state (or "off" state). good too. Such operation of the second transistor 422 may cause the shaping circuit 420 to extract energy from the charging pulse delivered to the battery cell 404 to ground. The extracted current is stored in the second inductor 424 , but since the current in the inductor lags the voltage, no current flows to ground while it is stored in the second inductor 424 . However, the off portion of PWM signal 426 is such that when current flows out of second inductor 424, transistor 422 is turned off and the energy signal extracted from the charge pulse is pulled to ground through connection 446 to either Transistor 422 may be rapidly closed so that nothing is transmitted. Rather, extracted energy may be channeled through flyback diode 430 to upper rail 442 and stored on storage capacitor 432 for reuse by charging circuit 400 .

By extracting energy from the charge signal, the input shaping circuit 420 may change the magnitude portion of the charge pulse to shape or distort the pulse to the battery 404 . In particular, control of the frequency of PWM signal 426 may extract more or less energy from the charge signal. Additionally, the duty cycle of PWM signal 426 may be selected or controlled to correspond to the duration of the charge pulse modification or shaping. Thus, PWM signal 426 , optionally provided by circuit controller 210 , may modify the charge signal from filter circuit 406 to battery cell 404 . Also similar to filter circuit 406 , one or more additional input shaping circuits 428 may be connected in parallel with input shaping circuit 420 . Each input shaping circuit 420 , 428 may be independently controlled by circuit controller 210 by an individual PWM control signal 426 . In another example, the same PWM control signal 426 may control more than one shaping circuit 420 . Also, one or more of the additional input shaping circuits 428 may have similar components with the same or different values. For example, the second input inductor of shaping circuit N 428 may have a larger or smaller inductance value than the second input inductor 424 of filter circuit 420 . Through control of the pulse control signal 416 and PWM signal 426 applied to the filter circuit 406 and/or the input shaping circuit 420, one or more of the charge signals applied to the battery cells 404 are adjusted to achieve a harmonic charge signal. The pulses may be shaped. Also, as described in more detail below, additional shaping of the input charging signal may be controlled by the circuit controller 210 to further modify the profile of the signal pulses. Various control signals of the circuit controller 210 may also be used to control the manner in which the charging signal is provided to the battery cells 404 . For example, the control signal may control the voltage at battery cell 404, the current supplied to the battery cell, or the overall energy or power supplied to the battery cell. Thus, while discussed herein as controlling or shaping the charging signal to the battery cells, it should be appreciated that any element of the charging signal may be controlled by the circuit controller 210. .

Circuit 400 of FIG. 4 may also include an impedance measurement circuit 408 connected to battery cell 404 . In general, impedance measurement circuit 408 measures impedance characteristics seen at the electrodes of battery cell 404 . In one example, the impedance measurement circuit 408 may include a voltage sensor that measures the voltage across the electrodes of the battery cell 404 and a current sensor that measures the current flowing through the battery cell. However, impedance measurement circuit 408 may include any known or hereafter developed circuit for measuring the impedance of battery cell 404 . Additionally, impedance measurement circuit 408 may be controlled by circuit controller 210 to measure cell impedance at various times or intervals. For example, impedance measurement circuit 408 may be configured to measure the impedance of battery cell 404 during a test in which a charging signal is applied to battery cell 404 over a range of frequencies. These measurements may be obtained and provided to circuit controller 210 to determine the minimum real impedance of battery cell 404 as described above with respect to graph 322 of FIG. 3B.

Circuit controller 210 may utilize circuit 400 of FIG. 4 to shape the pulses of the battery cell charging signal based on the frequency corresponding to the minimum impedance value. In particular, FIG. 5 illustrates a method 500 for generating a battery cell charging signal based on a frequency corresponding to a minimum impedance value, according to one embodiment. The operations of method 500 may be performed by circuit controller 210, and in particular by providing control signals to power supply 402, filter circuit 406, and/or shaping circuit 420 to control various configurations of circuit 400. control elements. Other circuit designs and components may also be controlled by circuit controller 210 to perform one or more of the operations of method 500 . Thus, although described herein with respect to circuit 400 of FIG. 4, the operations of method 500 may be performed by any number of hardware components, software programs, or combinations of hardware and software components. may be

Beginning at operation 502 , circuit controller 210 may select an initial frequency of charge pulses used to recharge battery cell 404 . For example, sinusoidal charging pulses may be selected for recharging the battery cells 404 to avoid the inefficiencies of square wave charging pulses. An initial frequency of the charging pulses may be selected by the circuit controller 210 . In some cases, the selected frequency may be determined to minimize or reduce the real impedance in the battery cell 404 during initial charging of the battery. Initially, no charge signal is applied to the battery and one or more characteristics (such as the state of charge of the battery cells or other electrochemical elements of the battery) may not be known, so the circuit controller 210 does not know the real impedance of battery cell 404 . Thus, the circuit controller 210 may initiate the delivery of energy to the battery cells 404 by selecting the initial frequency of the charging pulses. In one particular implementation, circuit controller 210 determines the initial frequency of the charge pulses based on historical data for battery cell 404, historical data for other battery cells, historical data for circuit controller 210, or other battery recharge data. may be requested. For example, circuit controller 210 may analyze past recharging sessions of battery cell 404 or other battery cells. Based on this analysis, circuit controller 210 may estimate the frequency f _Min of battery cell 404 at which the real impedance value of the battery cell is minimal. As the number of recharge sessions analyzed increases, the best estimate for the initial frequency of the charge pulse can be determined to correspond to the estimated minimum real impedance value of battery cell 404 . The initially selected frequency may not correspond to the actual minimum real impedance value of the state of charge of the battery cell 404, but rather one or more historical real values of the battery cell of interest or any other battery cell. It may be based on impedance measurements.

Depending on the initial frequency of the charging pulses selected, circuit controller 210 controls pulse control signal input 416 and/or PWM signal input 426 of charging circuit 400 to generate harmonic charging pulses for battery cell 404 . may In particular, circuit controller 210 may provide pulse control signal 416 to drive first transistor 412 for a first period of time. Driving the first transistor 412 may deliver a pulse of energy from the power rail 442 to the battery cell 404 . A first inductor 410 of filter circuit 406 resists the rapid increase in pulses (e.g., square wave pulses) received from power rail 422 to provide an angled leading edge (e.g., sine wave pulse) delivered to battery cell 404 . leading edge of the wave pulse) may be output. Also, the duration of the charge signal pulse may correspond to a first time period during which the first transistor 412 is driven to conduct. Additionally, the magnitude of the pulse may vary depending on the magnitude of the signal provided by power supply 402 (potentially controlled by V _CONT 434 ) and/or the duration of the pulse signal as controlled by pulse control signal 416 . It may correspond. In particular, the duration that the first transistor 412 conducts corresponds to the duration of the energy pulse supplied to the battery cell 404 . In many cases, the circuit controller 210 may provide a periodically repeating pattern of energy pulses to the battery cell 404 by repeatedly activating/deactivating the first transistor 412 .

In addition to the leading edge and pulse duration, control of the input shaping circuit 420 may effect modification of the energy pulse supplied to the battery cell 404 . In particular, the supply of a PWM signal 426 to a second transistor 422 causes the input shaping circuit 420 to extract energy from the pulse by rapidly activating and deactivating the transistor, causing the pulse to tap at any time during the duration of the pulse. The size may be reduced. The frequency of the PWM signal 426 may further alter the profile by controlling the amount of energy extracted from the energy pulse signal. By precise control of PWM signal 426, the pulse magnitude is reduced (by extracting energy from the pulse) or by turning off transistor 422 (to prevent energy from being extracted from the pulse by input shaping circuit 420). ) increase may generate a shaped pulse for charging the battery cell 404 .

Controlling inputs to circuit 400, such as pulse control signal 416 and/or PWM signal 426, causes circuit controller 210 to generate sinusoidal pulses for charging battery cells 404 at a selected initial frequency, similar to waveform 314 in FIG. 3A. may be generated. However, as mentioned above, the minimum real impedance in battery cell 404 may change during charging of the battery. For example, the state of charge and temperature of the battery cell 404 may change the minimum real impedance characteristic. By adjusting the frequency of the pulse charge signal to a frequency that corresponds to the minimum real impedance of the battery cells 404 in the current state of the battery, efficiency benefits are obtained in charging the battery. Accordingly, circuit controller 210 may measure the impedance of the battery cell at different frequencies in operation 506 to determine a function of the real impedance value of the battery cell at different frequencies. In one embodiment, the circuit controller 210 applies one or more test signals of different frequencies to the battery cell 404 so as to determine the charge signal frequency corresponding to the measured minimum real impedance of the battery cell 404. good too. The frequency of the test signal may be predetermined by circuit controller 210 to provide a range of test signals to battery cells 404 . For each test signal, a corresponding real impedance value at battery cell 404 may be determined and/or stored. Besides the use of multiple frequencies, galvanostatic intermittent titration (GITT) may be used. In general, GITT uses the characteristics of a square wave pulse (which is the sum of sinusoidal frequencies over the spectrum) to represent a complex impedance that can be used to determine the impedance of battery cell 404 .

At operation 508, a minimum real impedance value of the measured test impedance may be determined. For example, circuit controller 210 may select the lowest real impedance value from the received test results as the minimum impedance value. In another example, circuit controller 210 may analyze received real impedance values to determine a minimum real impedance value by extrapolation of the values. For example, the measurements may show that the real impedance value decreases for a series of test frequency increases, and then increases for the next series of test frequency increases. Circuit controller 210 is configured to determine that the minimum real impedance value of battery cell 404 corresponds to a frequency between a first set of increasing test frequencies and a second set of increasing test frequencies. good too. In this situation, circuit controller 210 may estimate the minimum real impedance value of battery cell 404 between measurements. At operation 510 , circuit controller 210 may determine a frequency corresponding to the determined minimum real impedance value for battery cell 404 . For example, a graph 334 of the real impedance value 324 of the battery cell 404 against the frequency 326 of the test signal may be generated, from which the minimum real impedance value 330 may be determined. Also from the graph 334, the frequency corresponding to the minimum real impedance value 330 may be determined. In general, any correlation algorithm for determining the frequency of the input signal to battery cell 404 that results in the lowest real impedance value may be used to determine the corresponding frequency.

At operation 512, circuit controller 210 may determine if the frequency corresponding to the lowest real impedance value of the measured test impedance is different than the previously selected frequency at which the charging pulse is delivered. If the circuit controller 210 determines that the corresponding frequency resulting from the application of the test signal to the battery cell 404 is different than the frequency at which the charging pulses are being supplied, then in operation 514 the circuit controller 210 applies additional pulses of the charging signal. corresponding frequency may be selected. Further, the circuit controller 210 may return to operation 504 to generate and provide an input signal to the shaping circuit to adjust the frequency of the charging pulses of the battery cells to the determined corresponding frequency. good. If the corresponding frequency does not differ from the frequency at which the charging pulses are being supplied, the circuit controller 210 maintains the frequency of the additional charging pulses in operation 514 and outputs the corresponding control signal to the shaping circuit in operation 504. may be supplied to Thus, the method 500 of FIG. 5 selects, for the sinusoidal charge pulses generated for recharging the battery cell 204, a frequency corresponding to the lowest real impedance value of the battery cell. good too.

A potential drawback of using a sinusoidal charging signal is that such a signal may provide less power to the battery cells for recharging compared to a square wave charging signal. . This potential drawback can be particularly pronounced in fast-charging situations, which seek to deliver the maximum amount of energy to the battery cells in the shortest amount of time. Graph 602 of FIG. 6 illustrates this potential drawback. In particular, FIG. 6 is a graph 602 of the input voltage value 604 over time 606 of square wave pulses 612, 614 and sinusoidal pulses 608, 610 of the battery charging signal. Generally, the area under each pulse indicates the amount of charge that can be supplied to the battery for recharging. It should be appreciated that the area under the pulse represents the amount of charge available. As noted above, due to battery and charging characteristics, generally not all energy of a square wave pulse is delivered for cell charging. Nevertheless, the difference in the amount of charge provided by the square wave pulses 612,614 and the sinusoidal pulses 608,610 is shown in the hatched areas 616,618. As shown, sinusoidal pulses 608, 610 reduce the impedance of the battery by estimating the selected harmonic frequencies described above, while allowing less charge to the battery per pulse than square wave pulses 612, 614. . Therefore, charging based on the minimum impedance frequency may provide improved charging over other systems. However, further refinements and optimizations are also believed to be available.

A potential way to provide a similar amount of charge to the battery at selected harmonics corresponding to the lowest real impedance value is to increase the charging pulses 608,610. However, because many battery characteristics impose an upper threshold on the magnitude of the charge signal, simply increasing the magnitude of the sinusoidal pulse may not be beneficial for fast charging of the battery cells. For example, many battery electrolytes begin to breakdown at certain power levels that correlate with voltage thresholds, and the irreversibility of such chemical reactions shortens battery life. Also, such electrolyte breakdown may occur at sudden changes in the recharging power signal applied to the electrodes of the battery. The rapid application of the recharge power signal can also cause dielectric breakdown or damage to other components of the battery. For example, high power signals may form one or more permanent channels across the solid electrolyte interphase (SEI) layer of a lithium-ion battery, rendering the entire anode permanently spatially inhomogeneous. The SEI layer also increases in thickness in response to high power signals, which can reduce battery efficiency. Additionally, increasing the magnitude of the recharge power signal can also potentially damage the battery and increase the risk of thermal runaway because the battery heats up faster than it can dissipate. Thus, simply increasing the pulses 608, 610 for additional charging can damage the battery during recharging.

An alternative way to increase the charging by the sinusoidal pulses 608, 610 is to keep the pulses at or near the pulse peak where the sinusoidal pulses normally begin to taper off, while combining the harmonics with the target real impedance minimum frequency ( and/or widening the peak and/or adjusting the leading edge of the pulse to achieve a target imaginary impedance (discussed in more detail below). In one example, the methods and circuits discussed herein are applied to determine a range of frequencies corresponding to one or more minimum real impedance values of a battery cell, and charge signals containing harmonics within these identified frequency ranges. may be supplied to the battery cell. For example, FIG. 7A is a graph 702 of measured real impedance values 714 of a battery cell versus corresponding frequency 706 of a charging signal applied to the battery cell. Values may be measured in real time, but may also be measured and stored (i.e. not measured in real time), characterized or derived from other information. or only periodically measured, and the frequency may be set to some initial value and then adjusted in a feedback loop. etc. shall be recognized. It should also be appreciated that other elements of the battery cell, such as imaginary impedance values, admittance values and/or susceptance values, may be measured or estimated as well and used to shape the charge pulse. good. The graph shows the highest frequency 710 and lowest frequency 708 that range between the minimum allowable impedance values, although the minimum impedance frequency value is not exact. Graph 702 of FIG. 7A is similar to graph 322 of FIG. 3B described above in that it represents a plot of the real impedance value of a battery cell versus the frequency of the charging signal supplied to the battery. However, in this example, rather than determining the frequency f _Min 332 corresponding to the minimum real impedance value 330, the lowest frequency f _RMin 708 and the highest frequency f RMin 708 are determined based on the range of acceptable impedance values for charging the battery cells. The range of frequencies defined by f _RMa 710 may be determined around the minimum real impedance value 712 of the battery. A minimum frequency f _RMin 708 and a maximum frequency f _RMa 710 are selected and included in the generated battery charge signal pulses to widen the profile of the pulses so that more charge is delivered to the battery cell in each pulse. may be By including multiple harmonics in the charge pulses of the recharge power signal based on the range of frequencies at the allowable impedance values, the recharge rate of the battery cells is reduced while maintaining a lower impedance of the battery cells undergoing the charge pulses. can increase the charge available from a single harmonic sine wave for

FIG. 7B is a signal diagram 722 of battery cell charge pulses including multiple frequencies corresponding to a maximum frequency f _RMax 710 and a minimum frequency f _RMin 708 based on the real impedance value of the battery cell, according to one embodiment. A signal diagram 722 shows input voltage 724 versus time 726, and when the highest voltage threshold 730 is exceeded, the battery can be damaged. In particular, charging pulse 728 of diagram 722 may be generated based on the range of frequencies shown in graph 702 of FIG. 7A. For example, charging pulse 728 of FIG. 7B may include a range of harmonics that lie between lowest frequency f _RMin 708 and highest frequency f _RMax 710 . In one example, the lowest frequency f _RMin 708 and the highest frequency f _RMax 710 correspond to the minimum real impedance value 712 determined for the battery cell, where the frequency f _Min 711 is the difference between the lowest frequency f _RMin 708 and the highest frequency f _RMax 710 . It may be based on a range around the minimum real impedance value 712 as may be included in between. For each selected harmonic frequency in the charge pulse 728, a corresponding magnitude may be determined based on the corresponding real impedance value of the battery at that frequency, whereby the charge pulse is somewhat uneven. However, none of the selected magnitudes may exceed the upper voltage or power threshold 730 where possible battery cell damage during recharging or possible thermal runaway of the battery. By extending the charge pulse by including the range of frequencies corresponding to the minimum real impedance value 712, the charge application for recharging the battery can be increased while maintaining a low impedance of the battery. Thus, using a high-charge, low-impedance charging signal to recharge a battery cell may improve efficiency compared to a square wave recharging signal.

FIG. 8 is a flowchart illustrating a method for generating battery cell charging signals based on different frequency ranges corresponding to maximum and minimum real impedance values of the battery, according to one embodiment. As noted above, similar method implementations may generate a battery cell charge signal based on other factors of the battery cell, such as the imaginary impedance value, the admittance value, and/or the susceptance value. Similar to method 500 of FIG. 5, the operations of method 800 of FIG. controls the various components of circuit 400 of FIG. Other circuit designs and components may also be controlled by circuit controller 210 to perform one or more of the operations of method 500 . Thus, although described herein with respect to circuit 400 of FIG. 4, the operations of method 500 may be performed by any number of hardware components, software programs, or combinations of hardware and software components. may be

Beginning at operation 802, the circuit controller 210 may determine the minimum real impedance value of the battery cell. Determining the minimum real impedance value can be similar to the above in that the circuit controller 210 can measure or receive the impedance of the battery at different frequencies of the charging signal. Alternatively, the minimum real impedance value may be determined by a loop process or circuit controller 210 driven process. For example, circuit controller 210 may charge the battery of the circuit at different frequencies (eg, a range of frequencies) and measure the impedance of battery cell 204 until the minimum impedance value of battery cell 204 is found. Such measurements may be taken during active charging of the battery cells, or may be performed and stored in memory and then searched. For some batteries, impedance measurements versus charge signal frequency may resemble graph 702 of FIG. 7A. Similar to graph 702, circuit controller 210 may determine a minimum real impedance value 712 for the battery cell based on multiple impedance measurements. The impedance measurement process may also include obtaining and storing impedance values at different frequencies (e.g., obtaining impedance measurements at frequencies above and below the lowest frequency, f _Min 711). ).

At operation 804, circuit controller 210 may select an upper real impedance value 720 for the corresponding range of acceptable impedance values. In particular, the circuit controller 210 may determine or be provided with an allowable impedance value 716 for the battery cell based on the application of the charging signal. The allowable impedance value 716 is shown and described as one allowable impedance value that is above the minimum impedance value and occurs at frequencies below and above the frequency f _Min 711 at which the minimum impedance occurs. It should be appreciated that the allowable impedance value 716 may not be the same for frequencies above or below the minimum impedance. Additionally, the allowable impedance 716 may change as charging progresses, changes in cell temperature, may be based on charging current levels, and the like. The allowable impedance value 716 may be greater than the minimum impedance value 712 determined above. For example, circuit controller 210 may determine or be provided with impedance value 716 as an acceptable impedance value for the charging signal. In general, the allowable impedance value 716 can be any impedance of a battery cell during recharging. However, a small allowable impedance value 716 may be selected or determined to limit the impedance across the battery cell when the charging signal is applied. Additionally, the upper impedance value 720 in this range may be an impedance value that occurs at a frequency or combination of frequencies different from the frequency at which the lowest frequency f _Min 711 occurs. In many cases, there will be a range of frequencies above the minimum impedance 712 and below the allowable impedance 716 above and below the frequency f _Min 711 at which the minimum impedance occurs. For example, this range of allowable impedances may occur at a frequency f _RMax 710 higher than the frequency at which the minimum impedance occurs. Thus, the circuit controller 210 determines or determines the upper impedance value 720 for the tolerance range by following the plot curve 714 of impedance values to the right (or higher frequencies) from the minimum impedance value 712 until the acceptable impedance value 716 is reached. It may be configured to select. However, in other implementations, the upper impedance value 720 of this range is the set difference from the minimum impedance value 712 (programmatically, from the minimum calculated considering other factors such as battery charge, temperature, etc.). setting difference). For example, the upper impedance value 720 of this range may be determined as twice the minimum impedance value 712 or some other multiple of the minimum impedance value.

Although shown as a smooth curve in FIG. 7A, the shape of plotted curve 714 of impedance values may include a variety of effects such as noise at different frequencies. For example, the plotted impedance values 714 may be generated at various signal magnitudes, such that they may contain subsidence at higher frequencies, especially at higher harmonics. Plot 714 may thus be the sum of a plurality of different plots, each associated with a different increment of harmonic power. In such a situation, the frequency f _Min 711 corresponding to the minimum impedance 712 may remain relatively constant while harmonics build up to a certain value at which the impedance value begins to rise rapidly.

In addition, the physical orientation of the cells in the pack (such as parallel or series connection) can affect the shape of the impedance curve due to parasitic capacitive and parasitic inductive losses. For example, the energy in a particular frequency band will jump from one cell to another over short distances in the air, effectively bypassing the cells in the battery pack structure and further increasing the current flow at that time. May inhibit or facilitate. Measured impedances at these frequencies are limited to local minimum impedances, especially for some harmonics on the higher frequency side, as omitting cells in the pack can cause subsidence of the impedance curve or areas that appear lower in impedance. A value may be determined. However, charging the battery cells or packs at these higher frequencies may not improve the efficiency of charging the battery cells for the reasons explained above. Therefore, the determination of the frequency f _Min 711 corresponding to the minimum impedance 712 may involve filtering out impedance values settling at high frequencies or relatively noisy bands due to parasitic losses in the battery pack. good. Such high frequency rejection may be accomplished by selection of inductor value 410 (or filter circuits 406, 418), or additional high frequency filtering in the path of the charging signal in circuit 400. may be included. In one embodiment, the controller 210 compares multiple parameters of the battery cell or pack, such as real and imaginary impedances, admittance, etc., to include local minimum impedance values while identifying areas to be excluded due to high frequencies. You may make it distinguish. Additionally, the controller 210 seeks to determine the range of frequencies associated with the lowest detected impedance value, since impedance droop due to parasitic losses in the battery pack may be associated with a small frequency range. may

Also, the impedance curve plot 714 obtained by the puck jumping energy between cells may be utilized by the controller 210 to characterize or identify the configuration of the puck. For example, a first battery pack configuration with cells connected in series may have a different impedance plot than a second battery pack configuration with cells connected in parallel. Also, detectable differences between packs with different cell numbers or orientations may be used as well. Thus, the controller 210 may obtain an impedance plot of the battery pack (as well as plots of other elements of the battery pack, such as conductance and/or susceptance) and compare the obtained plot to a database of impedance plots. good. The database of impedance plots correlates each plot with a particular battery pack configuration or battery cell type so that comparison of the acquired impedance plots with the stored plots allows the controller 210 to determine the battery pack configuration or cell type to be charged. It may be determined or estimated. Controller 210 may then further adjust or shape the charge pulse based on the estimated battery pack configuration.

Regardless of how the upper impedance value 720 in this range is determined, the circuit controller 210 may determine the corresponding frequency f _RMax 710 of the upper impedance value 720 at operation 806 . As previously mentioned, the impedance at the electrodes of a battery cell can vary based on the frequency of the charging signal applied to the electrodes. Thus, the frequency f _RMax 710 may correspond to a selected upper impedance value 720 within the acceptable range. Circuit controller 210 may determine frequency f _RMax 710 corresponding to selected upper impedance value 720 .

Also, at operation 808, the circuit controller 210 may select a lower impedance value 718 for a corresponding range of acceptable impedance values based on the minimum impedance value 716 obtained for the battery. Similar to the upper impedance value 720 of the range, the lower impedance value 718 may be selected or determined based on the allowable impedance value 716 and the frequency f _Min at which the minimum impedance value 712 occurs. It may be a frequency f _RMin 708 lower than 711 . In other words, the circuit controller 210 follows the impedance value plot 714 to the left (or down) from the frequency f _Min 711 at which the minimum impedance value 712 occurs until the allowable impedance value 716 is reached. It may be configured to determine or select a lower impedance value 718 for a range of impedance values. Thus, the upper impedance value 720 and the lower impedance value 718 are possibly equal (such as the range of allowable impedance values 716) but occur at different frequencies of the charge signal (eg, above and below the minimum impedance frequency f _Min 711). obtain. In another embodiment, the lower impedance value 718 for this range of impedance values, as well as the upper impedance value 720 for this range, may be a specified difference from the minimum impedance value 712 . Regardless of how the upper impedance value 720 is determined, the circuit controller 210 may determine the corresponding frequency f _RMin 708 of the lower impedance value at operation 810 . In general, the corresponding frequency f _RMin 708 is a lower frequency than the corresponding frequency f _Min 711 of the minimum impedance value 712 . In some examples, the tolerance range or set of harmonics for generating the charging pulse is based on the range of frequencies contained between the range of frequencies f _RMax 710 and the range of frequencies f _RMin 708 . , and this range also includes frequency f _Min 711 .

In still other implementations, circuit controller 210 may not determine either or both upper impedance value 720 or lower impedance value 718 . Rather, the circuit controller 210 may select (eg, look up a table, etc.) a frequency f _RMax 710 and a frequency f _RMin 708 for a range of impedance values. In some cases, one or both of the upper and lower frequency values may be based on the minimum impedance frequency f _Min 711, which is measured based on past modeling, extrapolation from past measurements, etc. , or may be obtained from memory. By selecting frequency f _RMax 710 and/or frequency f _RMin 708 based on minimum impedance frequency f _Min 711 , etc., circuit controller 210 may control the frequency range or bandwidth of the charging signal. Further, the frequency range may be such that the corresponding impedance values within that frequency range are for charging a battery cell based on measured impedance values of the battery cell or historical measurements of the battery cell or other battery cells. ) may be selected to remain below the tolerance threshold 716 .

At operation 812 , circuit controller 210 may determine magnitude values corresponding to a plurality of frequencies within a range of frequencies defined by frequency f _RMax 710 and frequency f _RMin 708 . In one embodiment, the magnitude corresponding to a frequency within the range may be proportional to the impedance measured or estimated at that frequency. For example, the magnitude sought to be included in a charging pulse at frequency f _RMax 710 may be proportional to the real impedance value 720 at that frequency. Similarly, the magnitude sought to be included in the charging pulse at frequency f _RMin 711 may be proportional to the real impedance value 712 at that frequency. Accordingly, each frequency within the range may have an associated magnitude corresponding to the impedance value 714 at that frequency. Note, however, that the impedance of each harmonic is not necessarily independent of the magnitude of the other harmonics of the waveform.

At operation 814 , circuit controller 210 may control the pulse control signal and PWM signal of charging circuit 400 to generate shaped charging pulses for battery cell 404 . As described above, the circuit 400 of FIG. 4 may be used to generate pulses of charging signals to battery cells 404 during charging. In particular, under the control of filter circuit 406 and/or input shaping circuit 420, power from upper rail 442 is shaped into a charging pulse train that includes one or more frequencies or harmonics corresponding to the frequency range determined above. You may make it In one example, filter circuit 406 can be controlled to produce a leading edge corresponding to a sinusoidal signal of frequency f _RMax 710 or frequency f _RMin 708 . Additionally, the duration of the pulse control signal 416 determines the harmonic range of the charging pulse, and a long duration of the pulse control signal 416 may correspond to a wide charging pulse (or wide bandwidth of the charging pulse). Input shaping circuit 420 may also be controlled by PWM signal 426 to vary the magnitude of the charging pulses at particular events or harmonics of the signal. Thus, circuit controller 210 provides one or more inputs to circuit 400 to include multiple harmonics based on a determined range of frequencies defined by frequency f _RMax 710 and frequency f _RMin 708 . A charging pulse can be shaped. The method 800 of FIG. 8 may cause the circuit controller 210 to generate a series of shaped charge pulses that deliver an optimum amount of charge to the battery 404 while maintaining or reducing the impedance at the electrodes of the battery cells.

The determined frequency range and the charging signal generated based on this frequency range may be used in accordance with method 500 of FIG. In particular, circuit controller 210 may generate charging signals from a range of frequencies based on the first set of measured impedance values to initiate charging of the battery cells. The iterative process discussed with respect to FIG. 5 may cause a second set of measured impedance values to be obtained during a battery cell recharging session. A second frequency range may then be determined based on the second measured impedance value and the charging signal adjusted accordingly. Thus, an iterative process of adjusting or modifying the pulses of the charge signal during recharging of the battery cell (reproducing the range of frequencies or harmonics contained in the charge signal) based on additional measurements of the impedance value of the battery cell. calculation) may be performed.

FIG. 9A is a signal diagram 902 of a shaped charging pulse train 902 generated from a battery charging circuit, according to one embodiment. In one example, circuit 400 may generate shaped pulses 914 , 916 based on controller 210 . A signal diagram 902 shows the input voltage 904 or input current versus time 906 for the current control hardware circuit for pulses 914, 916 of the charge signal. As can be seen, each pulse 914 , 916 is asymmetric with the leading edge 912 shaped differently relative to the trailing edge 910 . In one example, the pulses 914, 916 may be defined by a harmonic corresponding to or a combination of harmonics associated with the lowest impedance value seen at the electrodes of the battery cell. In particular, charging signal pulses 914, 916 may include a leading edge 912 corresponding to a selected frequency associated with the minimum impedance value of the battery cell. For example, the shape of leading edge 912 of pulse 914 may correspond to harmonic f _Min 332 identified by circuit controller 210 as the frequency at the minimum real impedance value of the battery cell. In one example, the shape of leading edge 912 may be based on the leading edge of a corresponding sine wave at the frequency of lowest impedance. In another example, the shape of leading edge 912 of pulse 914 may correspond to harmonic f _RMax 710 or harmonic f _RMin 708 . Identification of the minimum impedance frequency may be based, alone or in combination, on measurement(s), battery characteristics, among others. Regardless of the selected frequency, the leading edge 912 of pulse 914 is the portion of the harmonic sinusoidal charging signal that minimizes or reduces the impedance seen by the battery cell for more efficient application of the recharging power signal. It may be shaped to be the same as the leading edge.

Circuit controller 210 may control one or more of filter circuits 406 described above to generate leading edge 912 of pulse 908 of the selected harmonic. For example, the shape of leading edge 912 of pulse 908 may be correlated with the inductance value of first inductor 410 . In particular, the first inductor 410 resists rapid conduction of current so that the current through it rises slowly and increases over time. The resistance to current flow through the inductor is determined by the inductance value of the first inductor 410 . Thus, to shape the leading edge 912 of the pulse 914 of the charging signal, the circuit controller 210 causes current to start flowing through the inductor 410 and reach the battery cell 404 by driving the first transistor 412 (by the pulse control signal 416). You may do so. This current flow may begin slowly and increase over time, and since the voltage of the charging signal is related to the current of the charging signal, the voltage follows the current, as shown in FIG. 9A. may form the leading edge 912 of a pulse 914 that is uniform. In general, the rate of increase of the current through the first inductor 410 may be based on the inductance value of the inductor and may give the charging signal pulses 914, 916 a leading edge 912 shape. Thus, the harmonics of leading edge 912 may correspond to the inductance value of first inductor 410 . To apply the target harmonic to the leading edge 912, the circuit controller 210 selects from the plurality of filter circuits 406, 418 or the first inductor to apply the leading edge 912 corresponding to the determined harmonic of the lowest real impedance. may be generated. In addition, the resistance of the first inductor 410 to a rapid increase in current prevents the leading edge of the pulse of the charge signal from sharpening, suppressing high frequency harmonics that can occur in the battery cell 404 when square wave input is applied. .

Driving the first transistor 412 with the pulse control signal 416 may cause the circuit controller 210 to generate the leading edge 912 of the pulse 914 of the selected harmonic as current flows through the first transistor 412 . At later times in pulse 914 , the magnitude of the pulse may reach the upper or floating voltage of power supply rail 442 corresponding to constant voltage 908 on top of pulse 914 . The duration of pulse 908 is determined by circuit controller 210 by keeping first transistor 412 conducting such that power is supplied to battery cell 404 via first inductor 410 and first transistor 412 . It may be controlled. Thus, the pulse control signal 416 can control the duration or width of the pulses 914 of the charge signal.

Optionally, circuit 400 may be controlled to include a sharp trailing edge 910 of pulse 914 . The circuit controller 210 may turn off the first transistor 412 to isolate the battery cell 404 from the power rail 442 to produce the sharp trailing edge 910 of the pulse. In particular, circuit controller 210 may cause first transistor 412 to stop conducting by stopping pulse control signal 416 . As explained above, the current through the first inductor 410 when the first transistor 412 becomes non-conductive may be returned to the power rail 442 through the flyback diode 414 . Such control of the first transistor 412 may result in a sharp trailing edge 910 of the pulse 914 . Moreover, although a sharp trailing edge 910 may typically correspond to large harmonic content, after the sharp trailing edge 910 the current and voltage magnitudes drop to zero across the battery 404 (zero overpotential for voltage). Because they are close or equal, it is believed that such harmonics do not increase the impedance to damage the battery cell 404 . As will be described in more detail below with reference to FIG. 12, the magnitude of the voltage is temporarily reduced to the floating voltage of the battery (e.g. Isolation between large harmonics and damaging impedances is maintained as long as the voltage is below the battery voltage of . Thus, the filter circuit 406 controls the sine wave leading edge 912 of the harmonic corresponding to the minimum impedance value of the battery cell 404, the duration at the upper magnitude 908, and the low impedance at the electrodes of the battery. A shaped charge pulse 418 may be generated that includes a sharp trailing edge 910 that maintains and supplies sufficient charge to the battery cell 404 .

In general, the circuit 400 can be controlled to generate pulses of the charge signal or shape it into arbitrary shapes. For example, FIG. 9B is a signal diagram 922 of a second shaped charging pulse train 924, 932 generated from the battery charging circuit 400, according to one embodiment. In this example, the leading edge 928 of each pulse 926, 932 may be similar to the leading edge 912 described above with respect to FIG. 9A. In particular, leading edges 912 of charging pulses 924, 932 may be generated by controlling one or more of filter circuits 406 described above. However, in this example, the voltage level 908 is not a flat pulse for the duration of the pulse after the shaped rising edge 928, and the circuit controller 210 controls one of the input shaping circuits 420, 428 of the charging circuit 400 to Alternatively, multiple controls may further shape pulse 924 . In the illustrated example, portion 926 of pulse 924 following leading edge 928 may include voltage (or current) that drops unevenly to sharp trailing edge 930 . Although the drop level (or slope) 926 is shown linear, this is not required and the pulse 924 may be shaped to include many forms. In one embodiment, circuit controller 210 may provide PWM signal 426 to second transistor 422 of input shaping circuit 420 . As explained above, the PWM signal 426 may be a high frequency switching signal that alternates the second transistor 422 between a conducting state (or "on" state) and a non-conducting state (or "off" state). good. The rapid switching action of second transistor 422 allows current from pulse 924 to flow through second inductor 424 . The current extraction from this pulse 924 removes the current, resulting in a downward slope 926 . In general, the duty cycle of PWM signal 426, which may control the amount of current drawn from pulse 926, is configured by circuit controller 210 to produce slope 926 of pulse 924. may Further, as explained above, the off portion of PWM signal 426 is designed to rapidly close transistor 422 so that little or no energy signal extracted from the charging pulse is transferred to ground through connection 446. good too. Rather, extracted energy may be channeled through flyback diode 430 to upper rail 442 and stored on storage capacitor 432 for reuse by charging circuit 400 .

At the end of the period of charging pulse 924, circuit 400 may be further controlled to define a sharp trailing edge 930 as described above with respect to FIG. 9A. In particular, the circuit controller 210 may turn off the first transistor 412 to isolate the battery cell 404 from the power rail 442 to produce the sharp trailing edge 910 of the pulse. In particular, circuit controller 210 may cause first transistor 412 to stop conducting by stopping pulse control signal 416 . In yet another example, input shaping circuit 420 may be driven by PWM signal 426 to further shape the trailing edge of pulse 924 by sampling current at trailing edge 930 . Of course, the charging pulses 924, 932 shown in FIG. 9B are just one example of a shaped charging signal that may be generated by control of the charging circuit 400. FIG. In particular, circuit controller 210 may control filter circuit 406 and/or input shaping circuit 420 to generate charging pulses of various shapes as desired. Thus, other shapes of charging signals such as those shown in FIGS. 3A, 7B, and/or 9A may be produced by circuit 400. FIG.

Although described above with respect to real impedance values at the electrodes of the battery, the reactance or imaginary part of the impedance at the electrodes of the battery may also be considered when shaping the charge signal. Other factors such as admittance and/or susceptance values may also be considered. In particular, FIG. 10A is a signal diagram showing a sinusoidal voltage signal 1004 used to generate a charging current 1006 for recharging a battery cell. Generally, the charging current 1006 measured in the battery cell can have the same shape as the applied voltage signal 1004 . However, due to the impedance of the battery, the charging current 1006 applied to the battery is considered to be small and time delayed with respect to the voltage signal 1004 . The qualitative difference in magnitude between the voltage signal 1004 and the current 1006 in the battery gives the measured real impedance Z _R 1008 as Z _R =(dV/dI) or (ΔV/ΔI). One or more of the methods and circuits described above take this real component into account in shaping the pulses of the charge signal for recharging the battery. The time delay between voltage signal 1004 and application of current 1006 at the battery is shown as Z _I 1010 and is due to the reactive or imaginary component of the battery impedance. Similar to the real component of the impedance, the reactive portion 1010 of the impedance also causes inefficiencies in applying the charging signal to the battery during a charging session. For example, the duration of a charge waveform is typically from the beginning of recharging the battery with the charging voltage or current until the voltage slowly returns to zero overpotential (the voltage at the terminal matches the stray voltage of the battery) before charging the battery. Measured until current stops flowing (zero amperes). However, in a charging system that ignores the reactive part of the battery cell impedance, one can assume that the voltage to the battery and the resulting charging current waveform start and stop at the same time. However, considering the reactance part of the impedance, there is a capacitive or inductive time delay between the voltage and current waveforms in the battery cell, and the delay between the voltage and current of the charge signal determines the charge period per pulse. is shown to be longer. This is believed to increase the inefficiency of the charging pulse in the battery cell by reducing the average current over the charging duration of the pulse. Also, depending on the reactance level, the reactive component may channel energy into heat production rather than chemical energy stored in the battery. Reactance can also become a problem and heat can be generated in conductive paths (such as cables, wires, and wiring board traces) and in the cells themselves. High reactance can also lead to inhomogeneous electrochemical activity across the area of the electrode, and severe ohmic drops across the current collector, electroactive material, and other components within the battery cell.

To address potential inefficiencies in applying charging pulses to this battery cell, the system may generate a charging signal whose pulses correspond to a determination of the impedance or an estimated reactance component of the battery cell. . In particular, the pulse shape and overall duration of the charging signal for recharging the battery cells may be adjusted to accommodate the real component of impedance as well as the imaginary component of impedance. For example, reference is now made to FIG. 10B, which shows a graph 1022 of various components of the impedance 1024 of the battery versus the frequency 1026 of the charging signal applied to the battery. In particular, graph 1022 includes a plot of real impedance values 1028 , a plot of imaginary impedance values 1032 , and a plot of calculated nominal impedance values 1030 . By the methods discussed herein, the frequency f _Zr 1034 corresponding to the lowest real impedance value is determined and utilized to provide A charging signal may be generated in which the pulses contain harmonics. However, as shown in graph 1022, the frequency f _Zr 1034 corresponding to the lowest real impedance value may be associated with relatively high imaginary impedance values 1032 at the battery electrodes. Therefore, only considering the real impedance does not take into account the imaginary impedance and its effect on charging efficiency, and does not provide an optimal charging solution. Thus, some implementations of the circuits and methods described herein provide more or less insight into both imaginary and real impedances, such as understanding the frequency of both the imaginary and real components of impedance in a battery cell. Considerations may be made to optimize the frequency for defining pulse shapes and the duration of the overall charging signal over which such pulses are applied. Still other embodiments may use admittance and/or susceptance values calculated from measured real and/or imaginary impedances in the battery cells.

In one example, circuit controller 210 may calculate or obtain a combination of real and imaginary impedance values to select frequencies and harmonics at which to generate pulses of the charging signal. Such combinations may include normative calculations of real and imaginary impedance values. A plot of impedance reference values 1030 is shown in graph 1022 of FIG. 10B. Also, other combinations of both components of the battery's impedance can be calculated or determined by the circuit controller 210 and used to shape the pulses of the charge signal. For example, one or both of the real and imaginary impedance values may be unbalanced (such as 20% weighting for real impedance values and 80% weighting for imaginary impedance values) or proportional weighting. , and may also be used to determine various elements of the pulse of the charge signal, such as the leading edge or width of the charge pulse. Similar to the above, circuit controller 210 may determine a minimum impedance reference value and corresponding frequency (shown as frequency f _ZMod 1036 in graph 1022). As seen in graph 1022, generating charging pulses with harmonics of frequency f _ZMod 1036 induces a higher real impedance in the battery than at other frequencies (particularly compared to f _Zr ), while The imaginary impedance component can be minimized or reduced. Thus, by considering both components of impedance in the battery cell (real impedance 1028 and imaginary impedance 1032), a more efficient charging signal can be generated. Considering both components of impedance in a battery cell can be particularly useful in multi-cell systems where impedance is added by connections between the cells.

In some cases, the circuit controller 210 may select a frequency of the charging signal that is different from the frequency f _Zr 1034 corresponding to the minimum real impedance value and the frequency f _ZMod 1036 corresponding to the minimum nominal impedance calculation result. Rather, circuit controller 210 determines the harmonics of the charge signal by balancing real and imaginary impedance values such that the frequency selected for the charge signal can be between frequency f _Zr 1034 and frequency f _ZMod 1036. You may do so.

In one particular implementation, separate portions of the pulse of the charging signal may be shaped by the circuit controller 210 based on two or more impedance measurements. For example, FIG. 11 is a signal diagram of shaped pulses 1108 of a battery cell charging signal 1102 corresponding to two or more frequencies generated from a battery recharging circuit, according to one embodiment. Similar to the power signal pulse described above with reference to FIG. 9, the pulse 1108 may include a leading edge 1110 configured as a harmonic corresponding to the lowest real impedance value. For example, the shape of leading edge 1110 of pulse 1108 may correspond to harmonic f _Zr 1034 . However, the second portion 1112 of the pulse 1108 may contain harmonics based on another frequency different from the frequency f _Zr 1034 . For example, leading edge 1110 and second portion 112 may collectively include first harmonic f _ZMod 1036 corresponding to minimum nominal impedance calculation 1030 . To reduce the imaginary impedance at the electrodes of the battery due to the application of the recharge power signal, by determining the duration of the second portion 1112 of the pulse 1108 by applying a harmonic f _ZMod 1036 corresponding to the minimum nominal impedance calculation result. can be The determination and application of harmonics based not only on the real impedance component of the battery, but also on the imaginary impedance component enables the use of a more efficient recharging power signal for charging the battery cells.

Still other elements of the charging signal pulse may be controlled by circuit 400 . In particular, the control of the trailing edge of the charge signal pulse provides advantages in terms of efficiency when charging the battery cells. 12A and 12B are plots of the applied/measured voltage 1208 across the battery cell and the measured charging current 1210 of the battery cell versus time 1206, according to one embodiment. As mentioned above, the charge signal may include a sharp trailing edge that removes the charge signal 1212 to the battery cells. However, as can be seen in the plot of FIG. 12A, even when the voltage applied to the battery is set to zero, the current I does not drop to zero immediately, but has some delay before reaching zero. However, the time between pulses may be set such that the next pulse does not start until the current reaches zero (the cell is depolarized). Thus, in one example, the circuit 400 reduces the current in the battery cell 404 to zero to prevent inefficient charging by initiating cell polarization before potential damage or complete depolarization of the battery cell. Once reached, it can be controlled to wait until the next pulse of the charge signal starts. Since charging can only occur in pulses, shortening or minimizing the time between pulses reduces the overall charging time, other things being equal. For voltage controlled circuit 400 , the current component 1210 of the charging signal may lag the voltage component 1208 . More specifically, as shown in FIG. 12A, it may take some time for the battery current 1210 to return to zero after the battery voltage 1208 is removed. This delay in returning the battery current to zero can further reduce the efficiency of the charging pulse. Thus, in some implementations, the voltage 1208 of the charge signal can be controlled to be below the transition voltage corresponding to zero current represented as line 1206 in plot 1222 of FIG. 12, as shown in plot 1222 of FIG. 12B. . In general, the transition voltage 1206 is the voltage of the charge signal at which current flow to the battery reverses and can be similar to the floating voltage of a battery cell. In particular, allowing the voltage 1208 to fall below the transition voltage 1206 for a period of time following the trailing edge 1212 of the pulse (denoted as period T _T 1216) causes the current 1210 to drop to zero amperes more quickly than a pulse without a dip. can reach The duration T _T 1216 that the voltage 1208 of the voltage controlled charging circuit 400 is controlled below the transition voltage corresponding to zero current is determined by the circuit controller 210 to minimize the time for the current 1210 of the battery cell 404 to return to zero amperes. can be determined or set to reduce to In one example, the voltage droop can be controlled so that it does not fall below the recommended minimum cell voltage of the battery cell so that the electrodes of the battery cell do not deteriorate. Also, the magnitude of the voltage sink can be controlled to be a fraction of the magnitude of the charge pulse with respect to the transition voltage. Further, the voltage return to the transition voltage may be controlled at a rate that maintains the current at zero amperes as long as the charge in the battery cells remains balanced. Another charge pulse 1202 may be applied to the battery cell 404 when the current 1210 returns to zero amperes for a specified rest period. Thus, by shortening the time it takes for the current 1210 of the battery cell 404 to return to zero, the speed at which a charge pulse can be applied to charge the battery cell can be increased.

Although described above generally as a power control circuit, it will be appreciated that charging circuit 400 may be voltage controlled or current controlled, and each may be utilized in different situations. Both approaches are similarly controlled by measuring the voltage drop across the battery cell 404 and measuring the current through a current sensing resistor connected in series with the battery cell 404 . The main differences between control schemes are whether the current sensing hardware (such as a current sensing resistor) is external or internal to the power supply circuit (such as the power amplifier of power supply circuit 402), and the voltage drop and current across battery cell 404. Based on which sense resistor is processed first. In the case of a voltage controlled power supply, an initial voltage measurement may be taken across the battery cell 404 while the corresponding voltage drop across the external current sensing resistor is then measured to determine the current in the battery cell 404, such as by using Ohm's law. can be calculated. This allows the voltage of the charge signal to be precisely controlled, while the calculation of the current results in the voltage across the battery cell 404 being first measured and then the current of the battery cell being calculated.

A voltage controlled charging circuit may optionally be controlled to provide a charging signal having components as shown in FIG. In particular, the voltage of charge signal 1202 may be controlled to provide a flat voltage for the rest of the pulse after the sinusoidal leading edge 1214 as described above. A voltage-controlled charging signal may provide charging pulses with benefits as described above. A trailing edge 1212 may also be provided from the voltage control circuit 400 that includes a portion 1216 where the voltage is below the transition voltage corresponding to zero current in the battery cell 404 . Also shown in FIG. 12, it can be seen that the current calculation follows the voltage 1208 control since the battery cell 404 current 1210 lags the control voltage 1208 . Control of voltage signal 1208 allows circuit 1210 to return to zero amps before an additional charge pulse is similarly supplied to battery cell 404 . Another advantage of the voltage control circuit 400 is that the precise control does not exceed the thermodynamic threshold of the battery cell 404, and the dielectric breakdown of the battery cell 404, such as maintaining a voltage below the voltage at which the electrolyte of the battery cell 404 begins to breakdown. characteristics are prevented.

Also, the circuits and methods discussed herein may be implemented using a current controlled power supply. If the power supply of circuit 400 is current controlled, the current through the pre-calibrated sense resistor in the power supply circuit may be determined by the current through battery cell 404, so this resistance may provide the initial measurement. Therefore, by accurately grasping the charging current, it is possible to precisely control the charging current to the battery cell 404 without grasping the voltage drop of the entire battery cell. In this embodiment, the current into the battery cell 404 (as measured at the current sense resistor) can be inherently known (by the pre-calibration voltage at the sense resistor), while the voltage of the battery cell 404 is determined by this measured as a result of the applied current. FIG. 13 is a plot of measured current 1314 and voltage 1310 versus time 1306 across a current sensing resistor in a battery cell in response to a charging signal 1304 applied to the battery cell, according to one embodiment. As shown in plot 1302, the current to the battery cell 404 is controlled to produce a pulse similar to that described above with a sinusoidal leading edge 1314 followed by a constant current, possibly corresponding to the minimum impedance value of the battery cell 404. obtain. A trailing edge 1312 may also be provided from the current control circuit 400 that includes a portion 1316 where the current is below zero amperes corresponding to the stable transition voltage of the battery cell 404 . Also shown in FIG. 13, the voltage response 1310 of the battery cell 404 lags the control current 1308, indicating that voltage acts as a feedback response rather than the primary control factor.

In applications where simple components can be used or where the process is constrained by the existing power hardware of the device being charged, current control may be the default mechanism. Alternatively, in implementations where both the controller response time and the battery transient response are fast, the voltage and current control methods may behave similarly. However, when frequency increases and/or battery reactance reaches high levels, the behavior of these two methods may deviate and practical control considerations may be necessary.

The embodiments described above involve measuring or obtaining the impedance (real and/or imaginary) of the battery cell 204 to determine the frequency content of at least some of the pulses of the charging signal. The impedance value of the battery cell 204 may be obtained in various manners or methods. In one embodiment, the impedance of battery cell 204 may be measured or estimated in real-time upon application of a charging pulse to the battery cell. For example, the magnitude and time component elements of the voltage and current waveforms of the charging signal in battery cell 204 may be measured and/or estimated. Also, the difference between the measured magnitude and time components of the voltage and current waveforms may be used to determine or estimate the real, imaginary, or approximate impedance of battery cell 204 . For example, the leading edge consists of a single known harmonic, and voltage and current waveform magnitude differences can be obtained at consistent minimum and maximum values of the edge, so that the real and imaginary impedance values The value may be determined from the leading edge of the charge pulse. Similarly, the impedance component may be approximated from measurements of the voltage and current waveform magnitudes at the trailing edge of the charging pulse. In still other embodiments, the measurements may be adjusted based on weights applied to various measurements of the voltage and current waveforms of the charging signal. Generally, the impedance of battery cell 204 may be determined or estimated by determining or measuring multiple elements of the voltage and current waveforms of the charging signal. In another embodiment, hundreds or thousands of measurements of voltage and current waveforms may be acquired and analyzed by the digital processing system. Generally, the impedance of the waveform applied to the battery cell 204 can be more accurately analyzed with improved waveform fidelity and/or increased measurement results, so that the harmonics of the charging signal that produce the minimum impedance value Other factors of the effect of the component or waveform on the battery cell 204 can be more fully determined to determine the shape of the charge signal pulse.

FIG. 14 is a block diagram that illustrates an example computer device or computer system 1400 that can be used to implement the network embodiments disclosed above. In particular, the computing device of FIG. 14 is one embodiment of circuit controller 210 that performs one or more of the operations described above. A computer system (system) includes one or more processors 1402-1406. Processors 1402 - 1406 may include one or more internal level caches (not shown) and a bus controller or bus interface unit that directs interaction with processor bus 1412 . Processor bus 1412, also known as a host bus or frontside bus, may be used to couple processors 1402-1406 with system interface 1414. System interface 1414 may be coupled to processor bus 1412 and allow other components of system 1400 to interface with processor bus 1412 . For example, system interface 1414 may include a memory controller 1418 that interfaces main memory 1416 with processor bus 1412 . Main memory 1416 typically includes one or more memory cards as well as control circuitry (not shown). System interface 1414 may also include an I/O interface 1420 for interfacing one or more input/output (I/O) bridges or I/O devices with processor bus 1412 . One or more I/O controllers and/or I/O devices, such as I/O controller 1428 and I/O device 1430 , may be connected to I/O bus 1426 as shown.

I/O device 1430 also includes an input device (not shown) such as an alphanumeric input device including alphanumeric and other keys for communicating information and/or command selections to processors 1402-1406. good too. Another type of user input device includes cursor controls, such as a mouse, trackball, or cursor direction keys for communicating direction information and command selections to processors 1402-1406 and for controlling cursor movement on a display device.

System 1400 includes dynamic storage (referred to as main memory 1416) or random access memory (RAM) coupled to processor bus 1412 for storing information and instructions to be executed by processors 1402-1406. or other computer readable device. Main memory 1416 also may be used for storing temporary variables or other intermediate information during execution of instructions by processors 1402-1406. System 1400 may include read-only memory (ROM) and/or other static storage coupled to processor bus 1412 for storing static information and instructions for processors 1402-1406. The system illustrated in FIG. 14 is but one possible example of a computer system that can be employed or configured in accordance with aspects of the present disclosure.

According to one embodiment, the techniques described above are performed by computer system 1400 in response to execution by processor 1404 of one or more sequences of one or more instructions contained in main memory 1416 . may be These instructions may be read into main memory 1416 from another machine-readable medium, such as a storage device. Execution of the sequences of instructions contained in main memory 1416 may cause processors 1402-1406 to perform the process steps described herein. In alternative embodiments, the circuitry may be used in place of or in combination with software instructions. Accordingly, embodiments of the present disclosure may include both hardware and software components.

A machine-readable medium includes any mechanism for storing or transmitting information (eg, software, processing application) in a form readable by a machine (eg, a computer). Such media may take the form of, but are not limited to, non-volatile media and volatile media. Non-volatile media includes optical or magnetic disks. Volatile media includes dynamic memory, such as main memory 1416 . Common forms of machine-readable media include magnetic storage media (eg, floppy diskettes), optical storage media (eg, CD-ROM), magneto-optical storage media, read-only memory (ROM), random-access memory (RAM), erasable • Programmable memory (eg, EPROM and EEPROM), flash memory, or other types of media suitable for electronic instruction storage, including but not limited to.

It would be desirable for a battery-powered electronic system to be able to operate while being charged. Thus, for example, it would be advantageous if a battery-powered tool could operate while being charged. Similarly, the electronic system may operate in various states during charging. For example, mobile phones, tablets, laptop computers, etc. may be fully operational while charging, operate in various low-power modes while charging, or operate in some way while charging. Limiting functions may be operable. According to aspects of the present disclosure, a power converter, such as a buck converter or a boost converter, is provided in synchronization or coordination with circuitry that controls the charging waveform or energy flux at the electrodes of an electrochemical device (e.g., battery cell). It may work. The charging waveform includes frequency components and/or one or more harmonics associated with a minimum or low impedance (including real and/or imaginary components thereof or some combination thereof) of the electrochemical device to be charged. You can stay. The system can be controlled such that matching the charging signal, including the power signal, to the load does not disturb the shape or configuration of the charging waveform. Since the charging signal is intentionally controlled, it is convenient not to change its form or configuration. In particular, the system may control the power signal so as not to disturb the harmonically shaped leading edge of the charge pulse. Thus, for example, the harmonically defined leading edge of the charge form is maintained (eg, not distorted) while supplying power to any load. In another example, the system coordinates operation of the power converter for use with or in place of charging signal shaping and/or recycling functions. Also, the discharge (power signal) from the battery may be modulated with frequency/harmonic content based on the discharge impedance, which impedance is used to modulate the frequency/harmonic content of the charge waveform. It may be the same as the charging impedance, or it may be different. In any event, an element of the discharge signal may be adjusted.

FIG. 15 is a circuit diagram illustrating one possible circuit topology 1500 for generating shaped waveforms based on the impedance (or other measurement, such as susceptance) of a cell during charging. Since this system comprises the components introduced with respect to FIG. 4, the same reference numerals represent the same components between FIG. 4 and FIG. Generally speaking, this circuit may singly or cooperatively shape a waveform (e.g., the leading edge of a charging pulse) based on one or more harmonics and their respective effects on impedance. , 418 . As noted above, the filter circuit sections may each include a shaped inductor 410 . The filter circuitry may have inductors of the same or different values. In contrast to the circuit shown in FIG. 4, the circuit of FIG. 15 comprises power converter 1502 coupled between electrochemical cell 404 and load 1504 . In one example, the power converter is step-down converter 1506 . Generally speaking, a buck converter steps down the voltage of the power supply to the voltage required by the load. In another example, the power converter is a boost converter 1508 . Generally speaking, a boost converter boosts the voltage of the power supply to the voltage required by the load. In another example, both step-up and step-down converters may be provided in parallel and operated in response to the operating conditions or types of one or more loads. Also, the buck and boost operations can be adjusted to maintain the voltage output between the highest and lowest battery voltages. As discussed in more detail below, it is also possible to include one or more buck and/or boost parallel circuits to enable alternative output pulse control.

There are various possible examples of buck and boost circuit topologies. FIG. 16 shows an example charging circuit employing a step-down converter coupled between an electrochemical cell and a load. The circuit includes a filter circuit 406, such as described above with reference to FIG. 4, which is controlled by a control signal labeled "pulse" from a controller (eg, controller 210) to the filter transistors. be. The circuit further comprises a buck converter 1600 . The step-down converter is coupled with battery 404 . The buck converter comprises a transistor coupled to the battery and controlled by a control signal BUCK produced by the controller. FIG. 17 shows an example charging circuit employing a boost converter 1700 coupled between an electrochemical cell and a load. Similar to FIG. 16, this circuit includes a filter circuit 406, such as described above with reference to FIG. controlled by the control signal. The boost converter is coupled with battery 404 . The buck converter comprises a transistor coupled to the battery and controlled by a control signal BOOST produced by the controller. Also, other features of the circuits shown in FIGS. 4 and 15 may be included in one or both of the circuits shown in FIGS. Additionally, other buck or boost topologies may be employed.

FIG. 18 shows an example of the control of the various circuits of FIGS. 15-17. These control and charge pulses are associated with the circuit of FIG. However, these concepts are also applicable to circuits such as those shown in FIGS. 16 and 17 with fewer components or more complex circuits. FIG. 18A shows the voltage (top) and current (bottom) components of the adjusted charging pulse. As with the other pulses shown herein, this circuit uses frequencies and/or harmonics associated with the relatively low or lowest impedance of the cell being charged (the real and/or imaginary part of each is including) to shape the leading edge to fit. Also, with the impedance used in the above example, other measures may be used, such as the admittance or its susceptance and conductance components. As used herein, the term impedance may include its reciprocal admittance. As mentioned above, the impedance may change over time based on the electrochemical cell's state of charge, temperature, age, and/or number of cycles, and the like. Thus, waveforms can likewise be changed programmatically or dynamically based on feedback and impedance measurements. In one example, shaping may be performed by driving different combinations of filtering circuits to employ different combinations of inductors to shape the leading edge of the charge signal. Also, characterizing the impedance of the cell at various harmonics based on state of charge, temperature, age, etc., and any such characterization alone or in combination, rather than actual measurements of impedance. It is also possible to programmatically change the driving combination of the filter circuits to change the charging waveform based on

In any event, in systems that may require the application of some power to the load during charging, this application of power does not disturb the shape and frequency/harmonic characteristics and/or content of the charging waveform and is suboptimal. This may be done to help avoid applying waveforms associated with undesired impedance or waveforms that affect control of the charging waveform. However, it will be appreciated from the examples discussed in more detail below that in some cases the charge pulse may be shaped by driving a buck or boost circuit in some combination with a filter circuit. In any event, in one example, the buck or boost is not "on" for at least a portion of the charge pulse to avoid disturbing control of the shape of the leading edge and/or the shape or content of the waveform. The operation of the boost converter may be interleaved with the operation of the charge controller. In one example, the power converter is turned on only after the charging pulse is turned off. In another example, the power converter is turned on during the charging pulse on only after the leading edge transitions into the second "body" portion of the pulse following the shaped leading edge. good too. In another example, the power converter is turned off when the charge pulse is on. In another example, the power converter is turned off for some time before the charging pulse is turned on.

FIG. 18B shows control pulses that can be applied to various components of the circuit of FIG. 15 to drive the power converter to form and deliver the charging pulses of FIG. 18A and to deliver power to the load. . More specifically, FIG. 18B shows three different control signal pulses associated with forming and delivering conditioned charge signal pulses. These pulses can be run in sequence, defined at some frequency or duty cycle, and delivered in a variety of different configurations depending on the shape of the charging pulse desired. The definition of this example is merely a description of various concepts discussed herein and should not be construed as limiting in any way. A first pulse labeled "soft pulse" is applied to switch 412 and is the pulse control signal 416 of switch 412 . A second pulse labeled "hard pulse" is then applied to the switches of filter circuit N 418 . Depending on the shape desired for the charging pulse, one or more second pulses may be applied to one or more of the N filter circuits. Furthermore, if the first "soft pulse" is sufficient to shape the charging pulse, the second pulse can be omitted. A third "recycle" pulse is then applied to switch 422 as the recycle signal. The combination of the first and second pulses shapes the leading edge of the pulse. Depending on the inductance value of any given filter circuit and the desired harmonic characteristics of the leading edge, the filter circuits may be driven in a variety of possible combinations, the first of which will be discussed herein. and the second sequence are just examples. Similarly, various contemplated embodiments employ one or more filter circuits with the same or different inductor values and apply different control schemes to the different filter circuits to control the leading edge of the charge pulse. , other characteristics of the charging pulse may be defined, or the charging signal, whether pulse or not, may be defined more or less. Also, to provide the desired inductance value according to the target charging pulse shape, the various filter circuits are paralleled such that the parallel combination of inductors achieves the inductance value driven by any combination of filter circuits. may be driven in synchronism with. Also, direct connection in series or parallel of inductors in the filter circuit may give different possible values.

Finally, depending on whether the circuit includes a buck or boost branch and whether it requires a buck or boost function regardless of the operating mode of the load, the buck/boost pulses may It is applied to the boost circuit section. As noted above, in some embodiments it may be sufficient to have either a buck power converter or a boost power converter, while in other embodiments both buck and boost power converters may be sufficient. may be included. These exemplary control pulses are examples of discrete pulses that are part of such pulse trains (e.g., pulse width modulated (PWM) signals), typically applied at high frequencies as part of charge trains. thereby generating a charge train for charging the electrochemical device. According to the present disclosure, control of filter circuits (e.g., soft or hard), recycle functions, boost and buck circuits (e.g., PWM "buck" or "boost" control signals in each transistor of buck circuit 1600 or boost circuit 1700) by discretely and synchronously in various possible combinations of control signals (which may be PWM signals) for the various possible charging and/or discharging functions as discussed herein. It should be recognized that it is feasible.

18A, 18B and 15, when the first rising edge of the soft pulse occurs at time T0 and turns on switch 412, current begins to flow through electrochemical device 404 and voltage across the load. It can be seen to rise at terminal node 440 . At time T1, the rising edge of the hard pulse follows the soft pulse while the soft pulse is still high (and circuit 406 is still active). At time T1, in combination with the current from circuit 406 through switch 412, current from filter circuit N 418 begins to flow to the load. Thus, the charge pulse (leading edge shape) is dominated by the combination of filter circuit 406 and circuit N 418 .

In this example, the first pulse is labeled as a "soft" pulse because the current rises relatively slowly with larger inductors, so driving the circuit with a relatively large inductor will reduce the leading edge of the pulse. This is because the rise time of In this example, the reason the second pulse is labeled as a "hard" pulse is that a relatively small inductor causes the current to rise relatively quickly, so driving the circuit with a relatively small inductor results in This is because the rising time of the leading edge of the pulse becomes faster. In the illustrated example, the side-by-side combination of two filter circuits forms the rising edge shape of the charging pulse starting at time T0. Also, additional combinations may be employed to shape a rising edge that mimics a sinusoidal rising edge (e.g., additional filtering circuitry and/or fine tuning of switches in the filtering circuitry to shape the leading edge). can be smoothed and shaped like the first half of a sinusoidal pulse). It is also possible to provide different inductor values for the various circuits N 418, and control adjustments between any conceivable combination can define the shape of the leading edge of the pulse.

When V2 is reached, while the soft and hard pulses are still at a high level, the current flow in circuit N 418 reaches its maximum when the voltage at terminal node 440 reaches its maximum, which is essentially the rail. voltage minus the voltage drop across the switches in filter circuits 406 and 418 . The voltage at the terminals of a battery determines the amount of current that can flow through a load, and at a given voltage the amount of current tends to decrease over time. charge current decreases at times labeled V2 and V3.

At time T3, both the hard and soft pulses drop to zero and charging current from both circuit 406 and circuit N 418 ceases. At this point, the recycle portion of the circuit may be activated by applying a recycle pulse to switch 422 . As described above, the activation of the recycle pulse allows the current to return to zero quickly by diverting the charge on the terminal node to the storage capacitor 432 .

Additionally or alternatively, turning on a power converter (which may include a step-down circuit and/or a step-up circuit) may provide source energy to load 1504 . As introduced above, it may be desirable to power a load (eg, power tool, cell phone, vehicle function, etc.) at the same time that the battery is being charged. Also, as introduced above, in some cases a boost may be required to operate the load, and in other cases a step down may be required to operate the load.

As shown in FIG. 18B, the boost/buck pulses that drive the boost or buck switches, respectively, are occurring even while the charge pulse is not activated. In this example, if either the buck circuit or boost circuit is active between charge pulses, the battery powers the buck circuit or boost circuit and thus the load. In some examples, if the power converter is not operating, use of the recycle function causes the charge pulse voltage at the terminals to reappear as soon as possible after the charge pulse has turned off at the time associated with voltage V3. may be set back to zero. In one example, application of the recycle pulse drives recycle switch 426 . If the power converter functionality is present and operating, the power converter may be adapted to act as a substitute for the recycle pulse or may be adapted to cooperate with the recycle pulse.

Although the buck or boost circuits are shown operating with the charging pulse inactive, it is also possible to operate with the charging pulse active to further shape the pulse. However, in one example, such action is performed after the rising edge, or at least after the initial portion of the rising edge, so as not to distort the shape of the rising edge. Also, the function of the shaping circuit 428 may be replaced by the step-down or step-up operation in this example. Similarly, the buck or boost also acts in place of a recycling function that quickly returns the charge pulses to zero, rather than extracting energy from the battery to power the load, or In connection with drawing, there is the possibility of not recycling the energy that recycles the initial energy. For various uses of buck or boost circuits for coordinating with the capability of shaped and regulated charging waveforms where dynamic charging is possible, one or more capacitors may be used as buck branch or It should be recognized that a stable voltage of the load can be maintained by use in the boost branch.

In addition to controlling power delivery to the load through the power converter, aspects of the present disclosure also include controlling the power converter to shape the output pulses delivered from the electrochemical device to the load. Such pulse shaping may be performed in conjunction with charging, or may be performed independently. Accordingly, the shaping of the output pulse may be performed by the step-down circuit or the step-up circuit separately from the charging function, either alone or in various conceivable combinations. In one example, by shaping the output pulse from the electrochemical device to the load, at least the same benefits are achieved by harmonic shaping or adjusting the input charge waveform, such as shaping the leading edge of the charge pulse to the electrochemical device. can be brought about. In one example, the shape of the output waveform may be associated with power delivery from the battery with low or lowest impedance. In some cases, it can be assumed that the output impedance will be the same or nearly the same as the input impedance under the same conditions of the electrochemical device (eg, battery state of charge, temperature, age, etc.). In other cases, the output impedance is measured or characterized differently than the input impedance under different conditions, and the use of these different measurements or characterizations has led to the selection of the optimum output frequency characteristic. (It may be harmonic). Through the use of impedance measurement circuit 408, the output impedance from the load may be measured at different frequencies in a manner similar to that described above for measuring the input impedance to battery 404. FIG. In any event, in various examples, the output waveform (e.g., a conditioned pulse) from the battery to the load is shaped, and in certain examples, adjustment of the leading edge of the output pulse to a particular shape corresponding to frequency and /or harmonic shaping may be provided. Optimal harmonic or frequency characteristics are values that describe current flow to or from an electrochemical device, depending on whether charging or discharging (power delivery from the electrochemical device) is discussed. associated with.

The optimum frequency or harmonic can be associated with whatever the input or output impedance to the electrochemical device is minimized. However, in any given situation, it may not be the absolute minimum impedance, as the system chooses a value close to the minimum, or chooses values iteratively up to the minimum. In other situations, the nature of feedback loops and dynamic systems may cause the system to select a range of values around or associated with a minimum value. For example, even in a characterized system, the battery may not be fully characterized for state of charge, lifetime, temperature, or all other conditions, defining some portion of the charge or discharge waveform (e.g., discharge or to shape the leading edge of the charge pulse), reasonable extrapolations and assumptions can be made by the characterization. Thus, the use of "optimal" in the context of values such as impedance, harmonics (frequency), or other measures discussed herein to represent current flow to or from an electrochemical device is , does not necessarily mean that the minimum impedance value is known, or that the harmonic or frequency that gives that minimum is known by the system. Other measures may also be used, such as power, admittance, or its susceptance and conductance components, as described elsewhere herein. In the case of admittance, the optimum value may be associated with the harmonic that gives the maximum admittance or a value within some range of the maximum admittance upon charging or discharging.

In one example, the leading edge of the pulse from the battery may be shaped by control of switches in the buck circuit or boost circuit. For example, the switches (eg, transistors) of the buck circuit of FIG. 16 may be controlled by applying a variable duty cycle or variable period pulse train to the buck input. Alternatively, the boost switch of the boost circuit shown in FIG. 17 may be controlled by applying a variable duty cycle or variable period pulse train to the boost input. To harmonically shape the leading edge of the pulse exiting the electrochemical device so that it has a sinusoidal shape at a certain frequency, the system adjusts the duty cycle or After controlling the period, the duty cycle or period may be maintained for other durations of the pulse.

Also, harmonics, leading edges, etc. of the charge or discharge signal may be adjusted to match the impedance (or other value) of the electrochemical device to combine the charge or discharge interaction with the effect on the electrochemical device. can also be optimized. For example, the system balances battery charge rate and cycle life (e.g., number of charge and/or discharge cycles before battery capacity drops to some threshold, e.g., 75% (25% capacity loss)). is operable to allow In some cases, the system may determine the harmonic for the highest charge rate, but application of the signal to achieve that charge rate may not be optimal for cycle life. Therefore, the system may apply a lower charging rate than is possible, but application of such a lower charging rate can affect the impedance, thus altering the harmonic content of the charging signal. There is also the possibility of doing so. In other cases, the system controls a combination of duty cycle, frequency (e.g., of charge pulses), and/or full duration frequency (e.g., combined charge and rest) for harmonically tuned charging or discharging. The application of pulses may be used to balance various possible real-time battery characteristics, such as charge rate, and/or longer-term battery characteristics, such as cycle life. For example, a relatively high charge or discharge current results in a low cell impedance, which generally favors the charge or discharge rate, whereas a high charge or discharge rate is referred to herein as It will be appreciated that even when harmonically optimized by the complex impedance feedback discussed in , cycle life has some impact, similar to battery charging and discharging. Duty cycle has a large effect on peak current. On the other hand, if the current RMS is fixed, the minimum impedance frequency will reduce the charge rate, but may benefit the cycle life. Therefore, the system may be charged or discharged to optimize the balance between different factors. In other words, aspects of the present disclosure may act to improve the charge rate or discharge rate over the prior art, and such improvements may benefit others, such as optimizing cycle life under the above conditions. can be performed with regard to the desired results of In some such cases, the charge rate or discharge rate may remain improved over conventional systems, but operation at levels below the maximum may affect other factors. It may be balanced.

FIG. 19 illustrates one method of generating a harmonically shaped (eg, sinusoidal) leading edge of the output signal from the battery (which may be a shaped pulse train). That is, in the shaping portion of the charging pulse, the control pulse width can vary. For example, as shown in FIGS. 19A and 19D (highlighting the area of duty cycle changing portions of the buck/boost transistor control sequence of FIG. 19A), relatively short (nearly off) control pulse width pulses By changing from width to relatively long (near-on) pulse widths, the voltage/current initially rises relatively slowly, followed by a relatively faster rising leading edge over the same duration for each discrete pulse. , which mimics the shape of a sinusoidal leading edge of a discharge pulse (from a battery). The duty cycle may be uniformly increasing or non-uniformly controlled to provide a wide variety of possible shapes. Alternatively, the same pulse width (percentage) may be employed for each discrete pulse, while the duration varies from pulse to pulse.

In any event, the control sequence shown in FIG. 19A or its like may be applied at each discrete buck or boost pulse shown in FIG. 19B. In one example, the variable duty cycle or control sequence of FIG. 19A produces an output pulse train from an electrochemical device with harmonic shaped leading edges as shown in FIG. 19C. The duty cycle or period is controlled to form a system determined (or characterized) leading edge to match the optimum output impedance of the cell at any frequency. Also, the length of application of the duty cycle or period control can be controlled to shape the output pulse. In the example of FIG. 19C, the duty cycle is controlled to form the output pulse during the shaped leading edge. Then, in the body of the pulse, the duty cycle is constant for the rest of the pulse width.

PWM control of the buck or boost circuit can be thought of as grading the output current from the battery to the load in some "step" fashion. These steps may be smoothed out by filtering at the output of the electrochemical device. It may be built into the power converter or it may precede the power converter.

Controlling the duty cycle or duration of the control pulse may also be adapted to shape the charging pulse. Such duty cycle control may be performed alone or in combination with the methods described above, such that the inductance of the inductor 410 of each filter circuit is Based at least in part on the value and its effect on shaping the leading edge, a filter circuit and combination of filter circuits (eg, filter circuits 406 and 418) are selected to apply to some frequency profile. 19A and 19B, the first variable duty cycle control signal of FIG. 19A is applied as a pulse control signal 416 of switch 412, as shown in the dashed box portion of the "soft" pulse of FIG. 19B. It can be like this. A combination of so-called hard pulses, as described above and shown in FIG. 19B, may be used to shape the leading edge of the charging pulse, for example as shown in FIG. 18A. Control of the duty cycle provides the selection of different combinations of filter circuits as well as additional control functions to allow finer tuning of the leading edge in use.

Returning to the discussion of power converter functionality, it is also possible to employ one or more parallel step-up or step-down circuits, as shown in FIGS. 20A/20C and 20B/20D. In either case, the addition of one or more parallel buck or boost topologies offers, among other benefits, the opportunity to optimize efficiency for a single power converter design and power conversion. Alternate paths are provided for each parallel path, and the miniaturization of components in each parallel path may reduce heat loss and improve switching efficiency. In the example shown, the boost or buck inductors in the parallel circuits are not the same, and by reducing the inductor value in one circuit of each pair, the efficiency is potentially higher than in parallel circuits with relatively large inductors. . The inductor may be the same in one or both cases, and in various examples additional parallel buck or boost circuits may be employed. In one example, two or more parallel power conversion circuits, each powering a load, may be operating in parallel (eg, step-down or step-up). In another example, in each power conversion circuit in parallel, for example to shape the leading edge of the output pulse to match the harmonics giving the optimum output impedance, or to vary the duration of the pulse for the same purpose. , may use a varying duty cycle as shown. In yet another example, one of the circuits initially operates at a duty cycle that shapes the leading edge of the pulse, especially to reduce the initial supply current, and where higher current and/or stable output current is desired. Alternatively, one or more additional parallel circuits may be operated to supply current not available in a single power converter. In some cases, control flexibility is achieved by carefully controlling both the shape and amount of output current from the electrochemical device and providing additional parallel power converters, either alone or in combination with pulse-shaping control. It is considered desirable to

Various embodiments of the present disclosure have been discussed above in detail. Although specific implementations have been discussed, it should be understood that this is for illustrative purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without departing from the spirit and scope of the disclosure. Accordingly, the above description and drawings are illustrative and should not be taken as limiting in any way. Numerous specific details are provided to provide a thorough understanding of the present disclosure. However, in certain instances, well-known or conventional details have not been described so as not to obscure the description. A reference to one or an embodiment in this disclosure may be a reference to the same embodiment or to any embodiment. And such references mean at least one of these embodiments.

References to "one embodiment" or "an embodiment" mean that the particular feature, structure, or property described with respect to that embodiment is included in at least one embodiment of the present disclosure. The appearances of the phrase "one embodiment" in various places in this specification are not necessarily all referring to the same embodiment, or to separate or alternative embodiments mutually exclusive of other embodiments. do not have. Moreover, while various features have been described, these may be exhibited by some embodiments and not by others.

The terms used herein generally have their ordinary meaning in the art in the context of this disclosure and the specific context in which each term is used. Also, alternative phrases and synonyms may be used for any one or more of the terms discussed herein, and unless a term is specifically recited herein, no particular meaning is given. shall not be allowed. In some cases, synonyms for specific terms are given. A listing of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification, including examples of any term discussed herein, is exemplary only and is not intended to further limit the scope and meaning of the disclosure or any exemplified term. do not have. Likewise, the disclosure is not limited to the various embodiments provided herein.

Without intending to limit the scope of the disclosure, examples of instruments, devices, methods, and their associated results according to embodiments of the disclosure are provided. Note that titles or subtitles may be used in each example for the convenience of the reader, but they are not intended to limit the scope of the present disclosure. Unless defined otherwise, technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which this disclosure pertains. In case of conflict, the present specification, including definitions, will control.

Embodiments of the present disclosure include various steps described herein. These steps may be performed by hardware components or may be embodied in machine-executable instructions, by means of which a general-purpose or special-purpose processor programmed with instructions may be used. performs each step. Alternatively, these steps may be performed by a combination of hardware, software and/or firmware.

Various modifications and additions may be made to the described exemplary embodiments without departing from the scope of the invention. For example, although the embodiments described herein refer to particular features, the scope of the invention also includes embodiments having different combinations of features and embodiments that do not include all of the recited features. Accordingly, the scope of the invention is intended to embrace all such alternatives, modifications, and variations along with all their respective equivalents.

Claims (20)

a charging signal shaping circuit;
In operable communication with the charging signal shaping circuit to define a charging signal for the electrochemical device based on harmonics associated with values representative of current flow to the electrochemical device. a controller that controls the
a power converter operably coupled with the electrochemical device to supply power to a load;
charging system with The power converter is in operable communication with the controller, and the controller outputs a discharge waveform from the electrochemical device based on harmonics associated with values representing current flow from the electrochemical device. 2. The charging system of claim 1, controlling the power converter to generate . The charge signal comprises a series of regulated charge pulses, the discharge signal comprises a series of regulated discharge pulses, and the controller interleaves the series of regulated charge pulses with the series of regulated discharge pulses. 3. The charging system of claim 2, wherein the charging signal shaping circuit and the power converter are controlled such that: 4. The charging system of claim 3, wherein the regulated discharge pulse immediately follows the regulated charge pulse. 4. The charging system of claim 3, wherein an adjusted discharge pulse is activated in a body portion of an adjusted charge pulse, said body portion following a shaped leading edge of said adjusted charge pulse. 2. The charging system of claim 1, wherein the power converter includes at least one of a first buck converter or a first boost converter. 6. The power converter of claim 5, wherein the power converter further comprises at least one of a second buck converter in parallel with the first buck converter or a second boost converter in parallel with the first boost converter. Charging system as described. The power converter comprises a switch for controlling the power converter, the switch providing a pulse width control signal that varies from a substantially off pulse width to a substantially on pulse width to shape the edges of the output pulse from the load. 2. The charging system of claim 1, receiving. The charging signal shaping circuit
a first shaped inductor of a first inductance value in electrical communication with the power rail;
a first switching device in electrical communication with the first shaped inductor and configured to connect the electrochemical device to the power rail through the first shaped inductor;
The charging system of claim 1, comprising: The charging signal shaping circuit
a second shaped inductor of a second inductance value in electrical communication with the power rail;
a second switching device in electrical communication with the second shaped inductor and configured to connect the electrochemical device to the power rail through the first shaped inductor;
10. The charging system of claim 9, comprising: said controller sending a first control signal to said first switching device and a second control signal to said first switching device to thereby represent said current flow to said electrochemical device; 11. The charging system of claim 10, wherein the charging signal of the electrochemical device is defined based on the harmonics associated with . The first inductance value is greater than the second inductance value, and the first control signal causes the first switching before the second control signal turns on the second switching device. 12. The charging system of claim 11, wherein turning on a device shapes the leading edge of the charge signal based on the harmonic associated with the value representative of the current flow to the electrochemical device. The first inductance value is the same as the second inductance value, and the first control signal is applied to the first before the second control signal turns on the second switching device. 13. The charging system of claim 12, wherein turning on a switching device shapes the leading edge of the charge signal based on the harmonic associated with the value representative of the current flow to the electrochemical device. . 2. The charging system of claim 1, wherein the controller drives the power converter when the charge signal is off. 2. The method of claim 1, wherein said value is associated with a minimum impedance when a charging signal is applied to said electrochemical device, and wherein harmonic content associated with said minimum impedance is applied to said charging signal. charging system. The controller provides a control signal to the first switching device to generate a harmonically shaped leading edge of a pulse of the charging signal, the harmonically shaped leading edge being associated with the minimum impedance value. 10. The charging system according to claim 9. 17. The charging system of claim 16, wherein the control signal has a varying duty cycle or varying duration to produce the harmonic shaped leading edge. 2. The charging system of claim 1, wherein the value is at least one of impedance, admittance, and power. a controller for obtaining a value representing a current flow to an electrochemical device and associated with a harmonic component of said current flow;
a charging signal shaping circuit that defines a charging signal for the electrochemical device based on the harmonic component;
a power converter operably coupled with the electrochemical device to supply power to a load;
with
A power converter, wherein the controller delivers a control signal to the power converter to generate a harmonically adjusted output of the power converter based on an optimum impedance value of the electrochemical device during discharge. A method of power delivery comprising generating a discharge pulse from an electrochemical device that includes harmonically shaped edges defined based on harmonics associated with an output impedance of the electrochemical device.

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