WO2012007942A2

WO2012007942A2 - Power management system and method for an inductive power transfer system

Info

Publication number: WO2012007942A2
Application number: PCT/IL2011/000550
Authority: WO
Inventors: Arkady Katz; Arik Rofe; Moti Ashry; Oola Greenwald; Moti Kdoshim
Original assignee: Powermat Ltd.
Priority date: 2010-07-12
Filing date: 2011-07-11
Publication date: 2012-01-19
Also published as: WO2012007942A3

Abstract

Systems and methods for efficient power regulation of a power transmission element having a power input and a power output. An output monitor is configured to monitor at least one system parameter and an input controller is configured to control the power input. A feedback mechanism may be provided to send feedback signals relating to the at least one system parameter to the input controller. The input controller may adjust the power input of the power transmission element to control voltage drop across the power transmission element and control temperature and heat loss from the system.

Description

POWER MANAGEMENT SYSTEM AND METHOD FOR AN INDUCTIVE

POWER TRANSFER SYSTEM

FIELD OF THE INVENTION

The present invention is directed to providing power to electrical devices. In particular the present invention relates to electrical devices adapted to receive power inductively.

BACKGROUND

Electrical devices require power for operation. The voltage required for device operation varies across devices. An electric load within a device may draw energy power required for its operation from a power source. Power may be drawn from the source via a conductive connection using cables or by using wireless technologies such as inductive power.

Voltage supplied from a power source to a device is typically a constant value, regardless of the pre-defined voltage / potential difference required for the operation of each device. Moreover, voltage required by an electric load, for example voltage required to charge a battery or the like, may vary over time throughout the charging process.

Voltage supplied to a load may be regulated by power transmission elements.

The voltage drop across such power transmission elements is typically dissipated as heat. Energy loss is costly, environmentally undesirable and the heat may be damaging to system components.

Efficient use of available energy is of great importance for a number of reasons. On a global scale, there is increasing concern that the emission of greenhouse gases such as carbon dioxide from the burning of fossil fuels may precipitate global warming. Moreover, energy resources are limited. The scarcity of global energy resources alongside geopolitical factors drives the cost of energy upwards. Thus efficient use of energy is an ever more important budget consideration for the energy consumer.

Energy losses in electrical energy transmission are chiefly due to the incidental heating of current carrying wires. In many cases this is unavoidable, as current carrying wires are essential for the powering of electrical devices and current carrying wires have resistance. It is the work done to overcome this resistance which generates heat in the wires.

In other cases the energy losses are unnecessary. For example, electrical devices are often left running unnecessarily and energy used to power devices which are not being used is truly wasted. Various initiatives aimed at reducing the amount of energy wasted by idle devices have been proposed. For example, Energy Star is a joint program of the United States Environmental Protection Agency and the United States Department of Energy which awards manufacturers the right to display a recognizable label on products which meet certain energy consumption standards. Energy Star attempts to reduce energy consumption through better energy management.

Efficient energy management reduces energy wastage. For example, laptop computers, which rely upon a limited amount of energy supplied from onboard power cells, use a variety of strategies for keeping power consumption to a minimum. Thus the screen and hard drives are switched off automatically after the computer has been left inactive for a significant length of time, similarly the network card may be disabled when the computer is disconnected from the mains or from a network. Such energy management strategies may serve to increase the length of time that a device can be powered by its onboard cells.

Even when connected to the mains, however, efficient use of energy is essential. Many common electrical devices run on low voltage DC and typically use a transformer with an AC-DC power adapter to control the power provided to it. Energy Star estimates that 1.5 billion such power adapters are used in the United States alone for devices such as MP3 players, Personal Digital Assistants (PDAs), camcorders, digital cameras, emergency lights, cordless and mobile phones. According to Energy Star, such power adapters draw about 300 billion kilowatt-hours of energy every year which is approximately 11% of the United States' national electric bill.

The need remains, therefore, for a system for reducing energy losses in power supplies. Embodiments described hereinbelow address this need. SUMMARY

It is according to one aspect of the current disclosure to present a power regulation system for controlling a power transmission element, possibly of an inductive power transfer system, the power transmission element having a power input and a power output. The system may comprise: at least one output monitor configured to monitor at least one system parameter; at least one input controller configured to control the power input; and a feedback mechanism configured to send feedback signals relating to the at least one system parameter to the input controller. The input controller is operable to adjust the power input of the power transmission element in order thereby controlling the values of the at least one system parameter.

Variously, the power transmission element may comprise at least onelow- dropout regulator. Alternatively or additionally the power transmission element may compriseat least one inductive power receiving circuit.

Optionally, the inductive power transfer systemmay comprise at least one secondary inductor configured to inductively couple with a primary inductor associated with an inductive power outlet and the input controller comprises a driving unit configured to provide an oscillating electrical potential across the primary inductor. Accordingly, the driving unit may be configured to adjust transmission parameters of theoscillating electrical potential. For example, the operating parameters may be selected from a group consisting of operating frequency, operating voltage and duty cycle or the like.

Where appropriate,the feedback mechanism may comprise a data over coil driver. For example, the data over coil driver may comprise at least on ancillary load selectively connectable to a secondary inductor. Additionally or alternatively, the feedback mechanism may comprise at least one of a group consisting of optical elements, photosensitive elements, radio frequency transmitters and radio frequency receivers.

Optionally, the input controller is configured to maintain a constant voltage drop across the power transmission element. Alternatively or additionally, the input controller is configured to maintain a constant current.

Optionally, the output power comprises a voltage applied across an electrochemical cell. Accordingly, the input controller is configured to vary input voltage according to a charging cycle of the electrochemical cell. Variously, the monitored system parameters may be selected from a group consisting of: temperature, voltage output, current output and combinations thereof.

Where appropriate, at least one output monitor comprises at least one temperature sensor. For example, at least one temperature sensor may be selected from a group consisting of: thermistors, thermocouples, thermometers, temperature sensing chips and combination thereof or the like.

Optionally, at least one output monitor comprises at least one voltage monitor. Alternatively, or additionally, at least one output monitor may comprise a current monitor. The system may further comprise a current limiter.

According to some embodiments thepower regulation system may be incorporated into an integrated circuit. For example the system may be incorporated into an application specific integrated circuit (ASIC).

Furthermore, an application specific integrated circuit is disclosed comprising: at least one power regulation controller for controlling a power transmission element of an inductive power transfer system, and at least one inductive power transfer controller.

A voltage regulation system is herein disclosed which may be configured to control voltage drop across a power transmission element, comprising: an output voltage monitor; an input voltage controller configured to select an input voltage according to feedback from the output voltage monitor.

The power transmission element may comprise at least one low drop-out (LDO) regulator. Optionally, the power transmission element may comprise at least one charging circuit.

The input voltage controller may comprise an inductive power transfer system. The input voltage controller may further comprise an inductive power receiver configured to receive power from an inductive power outlet. Accordingly, the inductive power receiver may comprise a secondary inductor configured to inductively couple with a primary inductor associated with the inductive power outlet. The inductive power outlet may also comprise a driver configured to provide an oscillating electrical potential across the primary inductor. Optionally, the power transmission element may be selected by adjusting operating parameters of the driver. Such operating parameters may be selected from a group consisting of: operating frequency, operating voltage and duty cycle or the like. A feedback mechanism may be provided for transmitting the feedback signal from the inductive power receiver to the inductive power outlet. The feedback mechanism may comprise an inductive communication channel. Optionally, the feedback mechanism may comprise at least one of: optical elements, photosensitive elements, radio frequency transmitters and radio frequency receivers or the like.

The input voltage controller may be configured to maintain a constant voltage drop across the power transmission element. Alternatively or additionally, the input voltage controller is configured to maintain a constant current.

Optionally, the output voltage may be applied across an electrochemical cell. Accordingly, the input voltage controller may be configured to vary the input voltage according to a charging cycle of the electrochemical cell.

A further system for regulating voltage drop across a power transmission element is disclosed, comprising: an output voltage monitor; an input voltage controller; and a feedback mechanism configured to communicate the output voltage to the input voltage controller.

A method for regulating voltage drop across a power transmission element is taught. The method may comprise: selecting a required voltage drop 6V for the power transmission element; monitoring the output voltage V₂ of the power transmission element; and controlling the input voltage Vi of the power transmission such that V₂ - Vi = 6V.

A further method for regulating voltage drop across a power transmission element is disclosed comprising: providing an input voltage controller; providing an output voltage monitor; supplying voltage to the power transfer element; monitoring output voltage of the power transfer element; providing feedback to input voltage controller; and selecting a required operational voltage drop. Optionally, the method further includes controlling input voltage to maintain the required operational voltage drop. Alternatively or additionally the method may include adjusting reference parameters of output voltage. According to some embodiments, the method further includes providing a system temperature monitor; and monitoring system temperature during operation. BRIEF DESCRIPTION OF THE FIGURES

For a better understanding of the invention and to show how it may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings.

With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention; the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. In the accompanying drawings:

Fig. 1 is a block diagram representing the main elements of an embodiment of a voltage regulator system;

Fig. 2a is a graph illustrating a typical PRIOR ART charging profile for a power cell;

Fig. 2b is a graph representing an improved charging profile for a power cell using a voltage regulator system;

Fig. 3 is a block diagram representing a voltage drop regulator incorporated into an inductive power transfer system;

Fig. 4 is a circuit diagram of a possible charging circuit incorporating a voltage regulator system;

Fig. 5 is a block diagram representing the main elements of an embodiment of a voltage regulator system incorporating a temperature monitor;

Fig. 6 is a block diagram representing possible architecture is represented for a combined inductive power and power control integrated circuit; and

Fig. 7 is a flowchart representing a method for regulating voltage drop across a power transmission element. DETAILD DESCRIPTION

Reference is now made to Fig. 1 which shows a schematic block diagram representing the main components of an embodiment of a voltage-drop regulator system 100 for controlling the voltage drop across a power transmission element 200.

The power transmission element 200 is generally an active component used to transfer power from a power supply 240 to an electric load 220. Typically, the power transmission element 200 is configured to supply a desired voltage output V₂ when supplied with an unregulated input voltage Vi. Examples of power transmission elements 200 include voltage or power regulating elements such as linear voltage regulators, low dropout regulators (LDOs), switching regulators, charging circuits or the like which may be used to control charging of electrochemical cells or regulate voltage provision to an electric device for example.

It is noted that many power transmission elements used in electric circuits maintain the desired voltage output V₂ by receiving a higher voltage input Vi and shedding excess energy as heat. Therefore, thedifference between the input voltage Vi and the output voltage V₂, which is known as thevoltage drop 6V across the power transmission element, may be associated with a corresponding power loss. The power loss, which may be dissipated as heat from such power transmission elements, may be calculated as the product of the current flowing therethrough and the voltage drop there across:

(Power Loss) = (Transmission Current) X (Voltage Drop)

Consequently, power transmission elements, although important for the effective operation of many electric devices, may be inefficient components and avoidable causes of energy loss. Moreover, the heat generated by such lossy components may damage sensitive components of the electric circuit.

It is further noted that where the size of the host device is limited, for example in portable devices power transmission elements may place restraints upon the possible dimensions of the host device.In particular, heat dissipating elements may demand large surface areas to volume ratios.

Therefore, in the interests of efficiency of both power transfer and space, there is a need to reduce heat losses from power transmission elements of electric circuits. Accordingly, power management systems such as the voltage-drop regulator system 100 may be provided to regulate the voltage drop across the power transmission element 200 thereby improving the efficiency of power transfer.

According to one embodiment of the disclosure, the voltage-drop regulator system 100 may include an output voltage monitor 120, an input voltage controller 140 and a feedback mechanism 160. The voltage-drop regulator system 100 may control the voltage drop across the power transmission element 200 by adjusting the input voltage Vi supplied to the power transmission element 200 in accordance to the required value of the output voltage V₂. The voltage-drop regulator system 100 may be configured to maintain a low voltage drop 6V in order to reduce power losses.

Alternatively, or additionally, the power transmission element 200 may be optimized to work most efficiently with a given voltage-drop. Accordingly, the regulator system 100 may be configured and operable to maintain a constant voltage drop throughout the powering process. The constant operating voltage drop selected such that the operation of the power transmission element is most efficient.

Such voltage drop control may be provided, for example by the output voltage monitor 120 being operable to monitor the value of the output voltage V₂ and to communicate this value to the input voltage controller 140 via the feedback mechanism 160. The input voltage controller 140 may then be operable to adjust the input voltage Viin accordance to the monitored value of output voltage V₂so as to regulate the voltage drop 6V as suits requirements.

Alternatively or additionally, an operation voltage profile may be provided and the input voltage controller 140 may be configured to adjust the input voltage W over time in accordance to the operation profile. In one embodiment, the operation voltage profile may be stored in a memory, for example the memory of a microcontroller (not shown) and the input voltage controller 140 operable to communicate with the memory and determine the desired input voltage Vi accordingly. In other embodiments, a microcontroller may be operable to calculate required voltage values during the power transfer process, perhaps in response to other measurable operation parameters such as operating temperature, run time, charge level of electrochemical cells and the like.

In order to better illustrate the advantage of the disclosed system, reference is now made to the graph of Fig. 2a, showing a PRIOR ART voltage over time profile for the charging process of a power cell. The charging mechanism is configured to supply a charging voltage 11. The charging voltage 11 required by the cell typically varies over time along with the voltage of the cell as it charges. The voltage drop 6V(t) is represented by the gap between the constant supplied voltage 12 and the required charging voltage 11. It will be appreciated that the value of the voltage drop 0V(t) varies over time being initially very large before decreasing as the voltage of the cell increases.

Because of the uncontrolled voltage drop, charging mechanisms of the prior art may dissipate considerable amounts of heat particularly during the early stages of the charging process. As noted above, it may be advantageous to reduce this heat dissipation, for example, so as to improve the efficiency of power transfer as well as the dimensions and reliability of components of the system. The voltage regulator system 100 (Fig. 1) disclosed herein may be used to maintain a desired voltage-drop throughout the charging process thereby reducing energy losses.

Referring now to Fig. 2b, the voltage over time profile is shown for an improved charging process using an embodiment of the disclosed voltage regulator system 100. Here, the voltage supplied to the charging mechanism 12" is regulated such that the voltage drop 6V" and the associated charging current is near constant throughout the charging process. The value of the voltage drop 5V may be selected to match the most efficient voltage drop for operation of the charging mechanism for example.

Furthermore, the control provided by the voltage regulator system 100 allows the voltage drop 6V to be maintained at a lower level such that less heat is lost during the charging process. In contradistinction to the prior art, charging mechanisms using embodiments of the voltage-drop regulator system 100 (Fig. 1) may be configured to adjust the supplied voltage over time according to the required charging voltage 11.

By way of example and so as to better illustrate the function of the disclosed voltage regulator system 100, reference is now made to the block diagram of Fig. 3. The diagram illustrates how a voltage drop regulator may be integrated into an inductive power transfer system 1000 consisting of an inductive power outlet 1200 and an inductive power receiver 1300.

The inductive power outlet 1200 includes a primary inductor 1220 which is wired, via a driving unit 1230, to a power supply 1240, such as a power grid or a vehicle battery for example. The driving unit 1230 is configured to provide an oscillating driving voltage to the primary inductor 1220. As will be described below the oscillating driving voltage, where appropriate, may be selected to be at a frequency other than the resonant frequency of the inductive coupling system.

The inductive power receiver 1300 is configured to charge an electrochemical cell 1340. Additionally or in combination the inductive power receiver 1300 may be configured to power an electrical load 1400. The inductive power receiver 1300 includes a secondary inductor 1320, a power transmission element 1330 and a voltage drop regulator 1100. The secondary inductor 1320 and the power transmission element 1330 may be operable to power the electric load 1400 directly, to charge the electrochemical cell 1340 or selectively perform either function.

The voltage-drop regulator 1100 includes a controller 1110 and a feedback mechanism 1160. The controller 1110 is configured to monitor the voltage Vi supplied to the power transmission element 1330 and the output voltage V₂ of the power transmission element 1330 and to communicate with the driving unit 1230 via the feedback mechanism 1160. The driving unit 1230 is configured to receive the feedback signals and to control the voltage Vi supplied to the power transmission element 1330 accordingly.

The driving unit 1230 may include a controller 1232, configured and operable to control the voltage Vi by adjusting any of a variety of parameters depending upon the configuration of the system. For example, the driving unit 1230 may be variously configured to adjust the operating frequency of the system, the operating voltage supplied, the duty cycle or combinations of these parameters.

For example, where anon-resonant transmission frequency is used, the driving unit 1230may be configured to regulate power transfer by adjusting the transmission frequency. Where the frequency of transmission is higher than the resonant frequency of the system, a transmission frequency f_t, higher than the resonant frequency fR of the system, may produce a certain induced voltage of V_t. The induced voltage may be increased by reducing the transmission frequency so that it is closer to the resonant frequency fR. Conversely, the induced voltage may be reduced by increasing the transmission frequencyso that it is further from the resonant frequency fR.In other embodiments, a frequency of transmission below the resonant frequency may be selected and an increase in transmission frequency may cause an increase in induced voltage while a decrease in transmission frequency may cause a decrease in induced voltage.

Alternatively or additionally, other parameters such as duty cycle or amplitude of transmission voltage may be used possibly in combination to further regulate the amplitude of power transfer.

The feedback mechanism 1160 is provided to pass a signal Sj_n from the controller 1110 to the driving unit 1230. The feedback mechanism 1160 includes a signal emitter 1162 and a signal detector 1164. Various emitters 1162 and detectors 1164 may be used with the system as suit requirements. For example, infrared or other optical signals may be encoded and emitted by optical elements such as LEDs, lasers or the like. Optical signals may be detected by photosensitive elements such that a command signal may be sent to the driver 1230. Alternatively, radio signals may be communicated from radio frequency transmitters to radio frequency receivers using known protocols such as WiFi, Bluetooth or the like.

Alternatively, the feedback mechanism 1160 may use an inductive communication channel by which signals are transferred from the secondary inductor 1320 to the primary inductor 1230 concurrently with uninterrupted inductive power transfer. The inductive communication channel may include a transmission circuit and a receiving circuit. The transmission circuit is typically wired to the secondary inductor 1320, and the receiving circuit is wired to the primary inductor 1220.

The signal transmission circuit may include at least one electrical element, selected such that when it is connected to the secondary inductor, the resonant frequency fR of the system increases. The transmission circuit is configured to selectively connect the electrical element to the secondary inductor. Any decrease in either the inductance L or the capacitance C increases the resonant frequency of the system. Optionally, the electrical element may have a low resistance for example, with a resistance say under 50 ohms and about 1 ohm in one embodiment.

The signal receiving circuit may include a voltage or current peak detector configured to detect large increases in the transmission voltage. In systems where the voltage transmission frequency f_t is higher than the resonant frequency fR of the system, such large increases in transmission voltage may be caused by an increase in the resonant frequency fR thereby indicating that the electrical element has been connected to the secondary inductor. Thus the transmission circuit may be used to send a signal pulse to the receiving circuit and a coded signal may be constructed from such pulses.

According to some embodiments, the transmission circuit may also include a modulator for modulating a bit-rate signal with the input signal. The electrical element may then be connected to the secondary inductor according to the modulated signal. The receiving circuit may include a demodulator for demodulating the modulated signal. For example the voltage peak detector may be connected to a correlator for cross-correlating the amplitude of the primary voltage with the bit-rate signal thereby producing the output signal S_out.

In other embodiments, a plurality of electrical elements may be provided which may be selectively connected to induce a plurality of voltage peaks of varying sizes in the amplitude of the primary voltage. The size of the voltage peak detected by the peak detector may be used to transfer multiple signals.

For example signals may be coded by modulating power drawn from the system such that the peak pulses are detectable in the primary voltage having characteristic frequency. It is noted that signals may be data transfer signals communicating information to the driving unit 1230 such as system parameters and the like which the driver may use to calculate required input voltage Vi. Alternatively, the signals may communicate instruction signals to the driving unit 1230 for example requesting secondary voltage to be incrementally increased or decreased. Other examples of regulatory signals will occur to those skilled in the art.

Referring now to the circuit diagram of Fig. 4, selected electronic components are shown of a possible inductive charging circuit 4000 incorporating a voltage regulator system 4100.The charging circuit 4000 includes a power transfer element 4200, a low-dropout regulator (LDO) 4220, a microcontroller 4120, a Data Over Coil (DOC) driver 4140 and a current limiter 4160.

The power transfer element 4200, such as a battery charger or the like, is provided to control the load supply voltage. Accordingly, the power transfer element 4200 may incorporate an LDO 4220 operable to limit the output voltage V₂ of the power transfer element 4200 to a defined value, 3 volts say. It will be appreciated that other embodiments may use various voltage limiters to limit the output voltage V₂ to other values as required. The voltage regulator system 4100 is configured to control the voltage drop across a power transfer element 4200, such as a battery charger, connected to a rectifier 4330. A microcontroller 4120 is provided to monitor the input voltage Viand output voltage V₂ of the power transfer element 4120 and to send a feedback signal via a transmission circuit, such as theData Over Coil (DOC) driver 4140. The DOC driver 4140 is configured to connect aancillary load resistor 4142across two terminals of the rectifier 4330 selectively thereby altering the resonant frequency of the circuit and sending a feedback signal as described above. Accordingly the ancillary load 4142 is selectively connected to a secondary inductor 1320 (Fig. 3) thereby modulating power drawn by the secondary inductor 1320 from a primary inductor 1220 of an inductive power outlet 1200.

The current limiter 4160 may be operable to monitor the current drawn by the load, such as the charging current of a battery pack for example, and to prevent current from exceeding defined limits. The limiting current may be selected according to certain reference values as required. Such a current limiter where voltage may be provided to an electric load via multiple channels. In particular in inductive power transmission systems a battery pack, say, may be selectively chargeable by a conductive or an inductive pathway. Amongst other functionality, the current limit 4160 may be used to prevent power being provided simultaneously by more than one route. Alternatively or additionally, the current limiter 4160 may be used to limit the charging current in response to temperature measurements of the system so as to control energy losses due to voltage drop across the power transfer element 4120. Still other uses for the current limiter may occur to those skilled in the art.

The inductive charging circuit 4000 may be incorporated into an Application- Specific Integrated Circuit (ASIC) such as by being assembled into one Multi Chip Module (MCM) or implemented in a Monolithic IC or the like. ASICs generally have smaller dimensions than other integrated circuits and may be of particular application where space is limited. A known limitation upon the size of electrical components is the rate at which small components can dissipate heat. Typically, smaller components do not dissipate heat as well as larger components. Accordingly, a voltage regulator system such as disclosed herein may be incorporated into an ASIC thereby reducing heat generated by the circuit and the need for heat dissipation. Referring now to Fig. 5 showing another embodiment of a power regulator system 5100 for controlling a power transmission element 5200. The power transmission element 5200 may be an active component used to transfer power from a power supply 5240 to an electric load 5220. For example, the power transmission element 5200 may be an element of inductive power receiver circuit configured to supply a desired voltage output V₂ when supplied with an unregulated input voltage Vi. The power regulator system 5100 may include an output voltage monitor 5120, an input voltage controller 5140 and a feedback mechanism 5160 and a temperature monitor 5190.

The temperature monitor 5190 may be provided tomonitor internal temperature parameters measured in real time during power transmission. Accordingly, the voltage-drop regulator system 5100 may improve the temperature performance of power transmission, by an inductive power receiver for example. At high currents the energy losses due to the voltage drop across power transfer elements 5200 to be minimized. The output of the temperature monitor 5190 may be communicated to the voltage controller 5140 such that internal circuit parameters may be changed in response to internal temperature of the system, which may be measured in real time.

Various temperature sensors may be used to gather data for the temperature monitor such as thermistors, thermocouples, thermometers, temperature sensing chips and the like. According to various embodiments, multiple or common temperature sensors may be provided to monitor ambient external as well as internal temperatures of the power transfer system.

For example, an inductive receiver circuit for a 5 watt power level may draw up to about one amp of current. In such a case the voltage drop across an LDO FET may be major critical parameter as this voltage drop is a major cause for the losses and the temperature increase.

Where required, the voltage drop may be controlled by regulating the input voltage as described above. Alternatively or additionally, the reference voltage used by the LDO or reference current used by the current limiter may be adjusted such that the output voltage or current is limited directly. Still further voltage drop may be controlled by stopping the power supply altogether, at least for limited time periods. In the case of an inductive power receiver output power may be controlled, possibly when the temperature reaches a required value. For example, the efficiency of the components may be optimized for a particular temperature and the internal temperature of the system may maintained at this value. Accordingly, the inductive receiver may provide full power for a certain period of time and then may reduce power by controlling output voltage from the power transmission element and limiting the supply voltage to and/or the current drawn by the electic load, such as a power pack of a telephone, computer, tablet devicve, PDA, media player, communication device or the like.

It is noted that inductive power transfer systems are particularly suited to voltage drop regulation. In contradistinction to transformer based conductive power supplies, such as wall adaptors, USB supplies and the like, which generally provide constant output power, inductive systems tend to include regulator managing power transfer across the inductive couple. Inductive power receiving circuits may be incorporporated onto Application Specific Integrated Circuit (ASIC), for example being built into a Multi Chip Module (MCM), a Monolithic Integrated Circuit or the like. It will be appreciated therefore that there may be significant advantages to integrating a power regulation circuit and an inductive power transfer control circuit into a common ASIC. Such advantages include greater efficiency of space and less energy wastage than separate systems.

Referring now to Fig. 6, possible architecture is represented for a combined inductive power and power control ASIC. An inductive power receiver 6000 is configured to receive and input voltage VA, possibly from a secondary inductive coil (not shown), and to supply an output voltage VB to an electric load (not shown) of an electrical device such as a telephone, computer, tablet devicve, PDA, media player, communication device or the like. The electric load may further be powered by an internal power supply (not shown), such as an electrochemical cell, supercapacitor, capacitor bank, battery pack or the like, which is operable to supply a battery voltage VBAT. An internal power transfer element 6400 may be provided for controlling power supply to the electric load from the internal battery. Optionally, the inductive power receiver 6000 may be further configured to charge the internal power supply as required. The inductive power receiver 6000 includes a power transfer element 6200 for controlling the regulating the output voltage 6200 and an integrated control circuit 6100. The integrated control circuit 6100 may be in communication with both the internal power transfer element 6400 of the electrical device

The integrated control circuit 6100 includes an inductive charger control block

6120, an electrical device (mobile system) charger control block 6140, an inductive charger LDO control block 6160 and an electrical device (mobile system) LDO control block 6180.

The inductive charger control block 6120 may be used to control power transfer from an inductive power outlet (not shown) to the inductive power receiver 6000. The inductive charger control block 6120 may include signal transmission components such as a transmission circuit or the like to provide feedback to the inductive power outlet.

The inductive LDO control block 6160 may be used to control the voltage drop across the power transfer element 6200 of the inductive power receiver as well as the current drawn thereby.

The electrical device charger control block 6140 may be used to control power transfer from and to the internal power supply of the electrical device.

The electrical device LDO control block 6180 may be used to control the voltage drop across internal power transfer element 6400 of the electrical device.

Accordingly, when the mobile architecture is powered from inductive power outlet, VB voltage output is controlled by the inductive power control block 6120. In this case the inductive power control block 6120 may regulate the supply and the inductive LDO control block 6160 may keeps the input voltage VA following VB as described above.

When the mobile architecture charges the battery of the electrical device, VBAT voltage output may becontrolled by the inductive power control block 6120 allowing the charging process to be efficient.

When both system voltage VB and the battery charging VBAT outputs are required the logic, based on the input conditions: required current, initial VB voltage, initial VBAT voltage, etc., may determine which one of the algorithms and which control blocks will be operated to provide the most efficient power management. Where required the various control blocks may be provided on individual ASICs. However, the multiple control blocks may share certain functionality and may advantageously share common elements. Thus a combined inductive power receiver and voltage control ASIC presents a significant improvement over currently available systems.

For efficiency, the internal circuit parameters may be selected depending on the internal temperature, which may be monitored in real time inside the receiver.

Furthermore, embodiments of the integrated circuit for inductive power management and battery charging may incorporate an integrated voltage regulator and status transmitter and may be powered by a secondary inductive coil and rectifier bridge. The status transmitter may send feedback signals to an inductive power outlet via a transmission circuit including an ancillary load selectively connectable to the secondary coil of the inductive receiver.

Embodiments of the integrated may provide various functionality and amounst other elements may include the following:fixed voltage regulators for powering the internal circuitry and external load;clocks or other oscillating circuitsused for time generation needs and internal circuitry operation;precise internal voltage reference blocks;window comparator circuits;main power management devices; operation and control auxiliary circuits;modulator devices and driving circuits;signal transmission circuits;safety protection logic elements such as overtemperature, overcurrent, overvoltage protection circuits and the like;power management and battery charging control logic elements;communication logic elements for energy control;programming circuits for reprogramming of internal parameters;measurement circuitry for voltage and current measurement;timing circuits;mode selection circuitry;power consumption circuitry;alignment mechanisms;external charger detection circuits;temperature monitors;end of charge signal detectors; andcircuit breakers.

Reference is now made to the flowchart of Fig. 7 is a flowchart representing a possible method for regulating voltage drop across a power transmission element. The method includes: providing an input voltage controller 701; providing an output voltage monitor 702; and optionally providing a temperature monitor 708.During operation of the power transmission element the method includes supplying voltage to the power transmission element 703; monitoring the output voltage V₂ of the power transmission element 704; optionally monitoring system temperature 709; providing feedback to the input voltage controller 705;selecting a required voltage drop 6V for the power transmission element 706; and managing the voltage drop, possibly bycontrolling the input voltage V₁ of the power transmissionsuch that V₂ - Vi = 6V 707; additionally or alternatively reference parameters, such as reference voltage of an LDO or the reference current of a current limiter, associated with the output voltage V₂ may be adjusted. It is particularly noted that in inductive power transfer systems, the voltage drop may be managed by controlling the input voltage via adjustments to transmission frequency, duty cycle, amplitude of transmission voltage, combinations thereof or the like.

The scope of the present invention is defined by the appended claims and includes both combinations and sub combinations of the various features described hereinabove as well as variations and modifications thereof, which would occur to persons skilled in the art upon reading the foregoing description.

In the claims, the word "comprise", and variations thereof such as "comprises", "comprising" and the like indicate that the components listed are included, but not generally to the exclusion of other components.

Claims

1. A power regulation system for controlling a power transmission element of an inductive power transfer system, said power transmission element having a power input and a power output, the system comprising:

at least one output monitor configured to monitor at least one system parameter;

at least one input controller configured to control the power input; and a feedback mechanism configured to send feedback signals relating to said at least one system parameter to said input controller;

wherein said input controller is operable to adjust said power input of said power transmission element thereby controlling the values of said at least one system parameter.

2. The system of claim 1 wherein said power transmission element comprises at least one low-dropout regulator.

3. The system of claim 1 wherein said power transmission element comprises at least one inductive power receiving circuit.

4. The system of claim 1 wherein inductive power transfer system comprises at least one secondary inductor configured to inductively couple with a primary inductor associated with an inductive power outlet and said input controller comprises a driving unit configured to provide an oscillating electrical potential across said primary inductor.

5. The system of claim 4 wherein said driving unit is configured to adjust transmission parameters of said oscillating electrical potential.

6. The system of claim 5 wherein said operating parameters are selected from a group consisting of: operating frequency, operating voltage and duty cycle.

7. The system of claim 1 wherein said feedback mechanism comprises a data over coil driver.

8. The system of claim 7 wherein said data over coil driver comprises at least on ancillary load selectively connectable to a secondary inductor.

9. The system of claim 1 wherein said feedback mechanism comprises at least one of a group consisting of optical elements, photosensitive elements, radio frequency transmitters and radio frequency receivers.

10. The system of claim 1 wherein said input controller is configured to maintain a constant voltage drop across said power transmission element.

11. The system of claim 1 said input controller is configured to maintain a constant current.

12. The system of claim 1 wherein said output power comprises a voltage applied across an electrochemical cell.

13. The system of claim 12 wherein said input controller is configured to vary input voltage according to a charging cycle of said electrochemical cell.

14. The system of claim 1 wherein said system parameters are selected from a group consisting of: temperature, voltage output, current output and combinations thereof.

15. The system of claim 1 wherein said at least one output monitor comprises at least one temperature sensor.

16. The system of claim 15 wherein said at least one temperature sensor is selected from a group consisting of: thermistors, thermocouples, thermometers, temperature sensing chips and combination thereof.

17. The system of claim 1 wherein said at least one output monitor comprises at least one voltage monitor.

18. The system of claim 1 wherein said at least one output monitor comprises a current monitor.

19. The system of claim 1 further comprising a current limiter.

20. The system of claim 1 incorporated into an integrated circuit.

21. A power regulation system for controlling voltage drop across at least one power transmission element, the power regulation system comprising:

an output voltage monitor;

an input voltage controller configured to select an input voltage according to feedback from said output voltage monitor.

22. The system of claim 21 wherein said power transmission element comprises at least one LDO.

23. The system of claim 21 wherein said power transmission element comprises at least one charging circuit.

24. The system of claim 21 wherein said input voltage controller comprises an inductive power transfer system.

25. The system of any of claims 1 to 4 wherein said input voltage controller comprises an inductive power receiver configured to receive power from an inductive power outlet.

26. The system of claim 25 wherein said inductive power receiver comprises a secondary inductor configured to inductively couple with a primary inductor associated with said inductive power outlet.

27. The system of claim 25 or claim 26 wherein said inductive power outlet comprises a driver configured to provide an oscillating electrical potential across said primary inductor.

28. The system of claim 27 wherein said input voltage of said power transmission element is selected by adjusting operating parameters of said driver.

29. The system of claim 28 wherein said operating parameters are selected from a group consisting of: operating frequency, operating voltage and duty cycle.

30. The system of any of claims 21 to 29 further comprising a feedback mechanism for transmitting said feedback signal from said inductive power receiver to said inductive power outlet.

31. The system of claim 30 wherein said feedback mechanism comprises an inductive communication channel.

32. The system of claim 30 wherein said feedback mechanism comprises at least one of a group consisting of optical elements, photosensitive elements, radio frequency transmitters and radio frequency receivers.

33. The system of any of claims 21 to 32 wherein said input voltage controller is configured to maintain a constant voltage drop across said power transmission element.

34. The system of any of claims 21 to 32 wherein said input voltage controller is configured to maintain a constant current.

35. The system of any of claims 21 to 32 wherein said output voltage is applied across an electrochemical cell.

36. The system of claim 35 wherein said input voltage controller is configured to vary said input voltage according to a charging cycle of said electrochemical cell.

37. An application specific integrated circuit comprising:

at least one power regulation controller for controlling a power transmission element of an inductive power transfer system, and

at least one inductive power transfer controller.

38. A system for regulating voltage drop across a power transmission element, comprising:

an output voltage monitor;

an input voltage controller;

a feedback mechanism configured to communicate said output voltage to said input voltage controller.

39. A method for regulating voltage drop across a power transmission element, comprising:

selecting a required voltage drop 6V for said power transmission element; monitoring the output voltage V₂ of said power transmission element; and controlling the input voltage Vi of said power transmission

40. The method for regulating voltage drop across a power transmission element comprising:

providing an input voltage controller;

providing an output voltage monitor;

supplying voltage to the power transfer element;

monitoring output voltage of said power transfer element;

providing feedback to input voltage controller; and

selecting a required operational voltage drop.

41. The method of claim 40 further comprising:

controlling input voltage to maintain said required operational voltage drop.

42. The method of claim 40 further comprising: adjusting reference parameters of output voltage.

43. The method of claim 40 further comprising: providing a system temperature monitor; and monitoring system temperature during operation.