CN112436581A - Method and device for limiting energy feedback charging current - Google Patents
Method and device for limiting energy feedback charging current Download PDFInfo
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- CN112436581A CN112436581A CN202011323160.1A CN202011323160A CN112436581A CN 112436581 A CN112436581 A CN 112436581A CN 202011323160 A CN202011323160 A CN 202011323160A CN 112436581 A CN112436581 A CN 112436581A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00304—Overcurrent protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/18—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for batteries; for accumulators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/14—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
- H02J7/16—Regulation of the charging current or voltage by variation of field
- H02J7/24—Regulation of the charging current or voltage by variation of field using discharge tubes or semiconductor devices
- H02J7/2434—Regulation of the charging current or voltage by variation of field using discharge tubes or semiconductor devices with pulse modulation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/92—Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
Abstract
The embodiment of the invention relates to the technical field of current circuits, in particular to a method and a device for limiting energy feedback charging current, wherein the method is applied to energy recovery of an electric drive system, the electric drive system comprises a power supply battery and an electric motor, the electric motor works in an electric state or an energy feedback state, and the method comprises the following steps: determining that the motor works in an energy feedback state; the first charging current fed back by the motor is converted into a second charging current after being chopped, and the second charging current is used for charging the power supply battery; and determining the chopped chopping control signal based on the second charging current. A corresponding device for limiting energy feedback charging current is also provided. The device for limiting the energy feedback charging current provided by the invention has the advantages of simple structure and higher practicability, effectively avoids the damage of overlarge charging current to the power supply battery, and simultaneously improves the recovery efficiency of feedback energy.
Description
Technical Field
The present invention relates to the field of current circuit technology, and in particular, to a method and an apparatus for energy feedback charging current limitation.
Background
The typical electric driving system consists of a power supply, a motor controller and an action executing mechanism, wherein the motor is connected with a shaft and drives the action executing mechanism to act, the motor can work in an electric state or a power generation state, and typical power generation state scenes comprise scenes that motor energy is fed back for braking, a crane slowly puts down heavy objects, other gravitational potential energy is converted into electric energy through the motor, and the like. In an electric drive system using a battery as an important power supply energy source, if the motor works in a power generation state, on one hand, if the electric drive system can charge electric energy fed back from the power generation state of the motor into the battery, the energy utilization rate can be improved, and the endurance time of a product is prolonged; on the other hand, excessive feedback charging current may damage the battery, resulting in a decrease in battery capacity, a shortened life span, and even a fire.
Some devices for limiting the feedback electric energy exist in the prior art, but the devices have the following disadvantages:
1. the DC-DC conversion circuit comprises three DC-DC conversion functional modules, namely a current-limiting voltage-limiting module, a boosting module and a charging module, wherein each functional module comprises a power switch and a control circuit, and the hardware circuit structure is complex, so that the control method is complicated;
2. the power conversion stages are multiple, the energy loss is large, and the energy recovery efficiency is reduced;
3. the problem of redundant energy consumption generated when the energy recovery is carried out after the battery electric quantity reaches a set threshold value is not considered;
4. the charging current is limited in proportion with the braking voltage, the flexibility is lacked, and the recovery efficiency is reduced.
Disclosure of Invention
Accordingly, the present invention is directed to a method and apparatus for energy feedback charging current limiting, which at least partially solves the above problems.
In order to achieve the above object, a first aspect of the present invention provides an energy feedback charging current limiting method for energy recovery of an electric drive system, the electric drive system including a power supply battery and an electric motor, the electric motor operating in an electric state or an energy feedback state, the method comprising: determining that the motor works in an energy feedback state; the first charging current fed back by the motor is converted into a second charging current after being chopped, and the second charging current is used for charging the power supply battery; and determining the chopped chopping control signal based on the second charging current.
Preferably, the chopping comprises: chopping the first charging current into a series of pulse currents by using a first controllable switch, and smoothing the series of pulse currents through an inductor to obtain a second charging current; the chopping control signal is used for controlling the opening and closing of the first controllable switch.
Preferably, the chopping control signal is a PWM control signal, and the determining the chopping control signal for chopping includes: determining a duty cycle of the PWM control signal.
Preferably, determining the chopped chopping control signal based on the second charging current includes: judging whether the second charging current is larger than a set current threshold value, if so, reducing the duty ratio of a PWM control signal output to the first controllable switch based on the current PWM control signal; if so, increasing the duty ratio of the PWM control signal output to the first controllable switch based on the current PWM control signal.
Preferably, the duty ratio of the PWM control signal is preset to a minimum value; and determining that the current battery power of the power supply battery is higher than a protection threshold value or in a situation of being incapable of charging, wherein the duty ratio of the PWM control signal is the minimum duty ratio.
Preferably, the method further comprises: and dissipating the current converted from the first charging current to the second charging current.
Preferably, the dissipation comprises: controlling the communication of the first charging current and the electric energy dissipation device by adopting a second controllable switch; the second controllable switch is controlled by an inverted signal of the chopping control signal and is opposite to the opening and closing state of the first controllable switch.
Preferably, the method further comprises: and the first charging current flowing into the first controllable switch when the first controllable switch is closed is stored, and the energy storage is utilized to supply energy to the inductor when the first controllable switch is opened.
In a second aspect of the present invention, there is provided an energy feedback charging current limiting apparatus disposed between a power supply battery and an electric machine of an electric drive system, the electric machine operating in an motoring state or an energy feedback state, the apparatus comprising: the determining component is used for determining that the motor works in an energy feedback state; the conversion component is used for converting the first charging current fed back by the motor into a second charging current after chopping and charging the power supply battery; control means for determining the chopped chopping control signal based on the second charging current; and a dissipating component for dissipating the current converted from the first charging current to the second charging current.
Preferably, the conversion member includes: a first controllable switch for chopping the first charging current into a series of pulsed currents; and the inductor is used for smoothing the series of pulse currents to obtain the second charging current.
Preferably, the control means includes: the current sampling circuit is used for acquiring the coupling current of the second charging current and determining the measured value of the second charging current; a logic controller for determining a waveform parameter of the chopping control signal based on stored control logic and measurement values, and a waveform generator for generating the chopping control signal according to the waveform parameter.
Preferably, the control logic comprises: determining that the second charging current is greater than a set current threshold, and reducing a duty cycle of a PWM control signal output to the first controllable switch based on a current PWM control signal; determining that the second charging current is less than a set current threshold, increasing a duty cycle of a PWM control signal output to the first controllable switch based on the current PWM control signal; and determining that the current battery power of the power supply battery is higher than a protection threshold value or in a situation that the power supply battery cannot be charged, wherein the duty ratio of the PWM control signal is a preset minimum duty ratio value.
Preferably, the apparatus further comprises: and one end of the capacitor is connected with the connecting end of the inductor and the first controllable switch, and the other end of the capacitor is connected with the negative electrode of the power supply battery.
Preferably, the dissipating component receives the current to be dissipated through the second controllable switch; the second controllable switch is used for controlling the communication of the first charging current and the dissipation component; and when the motor works in an energy feedback state, the second controllable switch is opposite to the opening and closing state of the first controllable switch.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
1) the scheme has simple logic and higher practicability;
2) the feedback charging current can be increased as much as possible under the condition of limiting the feedback charging current, and the charging capacity is improved; when the battery is full of electricity, the electric energy which can not be recovered by the battery can be consumed through the resistor.
3) Compared with the traditional multi-stage limiting module, the problems of multiple power conversion stages and large energy loss are solved, and the energy recovery efficiency of the device is improved.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic diagram illustrating a method for energy feedback charging current limiting according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating an exemplary method for energy feedback charging current limiting according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an apparatus for energy feedback charging current limiting according to an embodiment of the present invention;
FIG. 4 is a block diagram of an exemplary embodiment of an apparatus for energy feedback charging current limiting;
fig. 5 is a diagram illustrating simulation results of an apparatus for limiting an energy feedback charging current according to an embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration and explanation only, not limitation.
Fig. 1 is a schematic diagram illustrating steps of a method for energy feedback charging current limitation according to an embodiment of the present invention, and as shown in fig. 1, the method for energy feedback charging current limitation is applied to energy recovery of an electric drive system, the electric drive system includes a power supply battery and an electric motor, the electric motor operates in an electric state or an energy feedback state, and the method includes:
s01, determining that the motor works in an energy feedback state;
when the electric vehicle is in a driving working condition, the power supply battery or the battery pack is used as a main power source, the motor is used as a mechanical power source of the electric vehicle, the electric vehicle works in an electric state, and electric energy is converted into kinetic energy for driving the electric vehicle to run. Under the working condition of energy feedback, the motor is driven by external mechanical force and works in an energy feedback state to generate feedback current. Energy recovery of the feedback current can improve energy utilization rate. However, the feedback current is unstable, the fluctuation of the current value is too large, and the excessive feedback current may damage the power supply battery.
S02, converting the first charging current fed back by the motor into a second charging current after chopping, and charging the power supply battery;
chopping mainly means that an original straight power supply is chopped into pulses by a circuit in the voltage regulation process of a switching power supply. The first charging current is converted into the second charging current through chopping, the charging current of the power supply battery can be controllably adjusted, damage to the power supply battery when the first charging current is too large is avoided, and energy loss caused by fixed current conversion when the first charging current is too small is also avoided.
S03, and determining the chopped chopping control signal based on the second charging current.
The embodiment controls the chopping control signal through negative feedback by collecting the second charging current. And when the second charging current is larger, reducing the chopped current by reducing the chopping interval, or increasing the chopped current by increasing the chopping interval when the second charging current is smaller, so that the stability of the charging current for the power supply battery is kept. Meanwhile, a high current conversion rate can be ensured when the first charging current is small.
And S04, converting the first charging current into a current except the second charging current for dissipation.
When the first charging current is chopped, the first charging current is divided into two parts, one part is converted into the second charging current, and the other part is not recycled and charged. This portion of the unrecovered current may be used for additional purposes or may be dissipated. This embodiment is designed to dissipate this, mainly in consideration of simplification of the circuit configuration. Through the above embodiment, the stability of the charging current to the power supply battery can be kept through simple regulation, the energy loss is small, and the energy recovery rate is high.
In one embodiment provided herein, the chopping comprises: chopping the first charging current into a series of pulse currents by using a first controllable switch, and smoothing the series of pulse currents through an inductor to obtain a second charging current; the chopping control signal is used for controlling the opening and closing of the first controllable switch. When the first controllable switch is turned off, the passing current is 0, and when the first controllable switch is turned off, the first charging current passes through the switch. Therefore, when the first controllable switch is switched to an open state and a closed state, the continuous first charging current is converted into an intermittent current, namely a series of pulse currents, so that the energy of the charging current is reduced. The first controllable switch is preferably a power switch tube IGBT, and has the advantages of high switching speed and large working current. And smoothing the series of pulse currents by using the current impedance action of the inductor so as to obtain a stable second charging current. The chopping control signal is used for controlling the opening and closing of the first controllable switch, so that the control of the second charging current is realized. The above embodiment has the advantages of simple circuit structure, low energy consumption of elements and high reaction speed.
In one embodiment of the present invention, the determining the chopped wave control signal is a PWM control signal, and the determining the chopped wave control signal includes: determining a duty cycle of the PWM control signal. Pulse Width Modulation (PWM) is a signal made up of a series of pulses, with high and low levels in the PWM control signal corresponding to the closing and opening of the first controllable switch. In the prior art, frequency can be modulated by changing the period of a pulse train, voltage can be regulated by changing the width or duty ratio of pulses, and the voltage and the frequency can be changed coordinately by adopting a proper control method. The purpose of controlling the charging current can be achieved by adjusting the period of PWM and the duty ratio of PWM. In the embodiment, the duty ratio of the PWM control signal is adjusted to control the first controllable switch, so as to control the second charging current.
In one embodiment of the present invention, determining the chopped chopping control signal based on the second charging current comprises: judging whether the second charging current is larger than a set current threshold value, if so, reducing the duty ratio of a PWM control signal output to the first controllable switch based on the current PWM control signal; if so, increasing the duty ratio of the PWM control signal output to the first controllable switch based on the current PWM control signal. The first controllable switch is controlled by the PWM control signal, when the duty ratio of the PWM control signal is increased, the on-time in one period is increased, the off-time is reduced, correspondingly, the first charging current passing through the first controllable switch is increased, the interval between pulse currents is reduced, and therefore the current of the second charging current is improved. And vice versa. The duty ratio of the PWM control signal is determined by detecting the magnitude of the second charging current, and the second charging current is adjusted by the on-time of the first controllable switch, so that the purposes of negative feedback and current stabilization are achieved.
In one embodiment provided by the present invention, the duty ratio of the PWM control signal is preset to a minimum value; and determining that the current battery power of the power supply battery is higher than a protection threshold value or in a situation of being incapable of charging, wherein the duty ratio of the PWM control signal is the minimum duty ratio. When the power of the power supply battery is higher than the protection threshold value or the power supply battery cannot be charged, the PWM duty ratio is adjusted to be minimum, and the electric energy generated by braking is not recovered. The minimum value of the duty ratio is preferably 0%, that is, the first controllable switch is in a normally open state, so that the first charging current fed back by the motor can not be converted into the second charging current.
Fig. 2 is a diagram illustrating steps of a method for limiting energy feedback charging current according to an embodiment of the present invention, and as shown in fig. 2, a logic control diagram is briefly described as follows:
when the motor works in an energy feedback state, the power supply battery is detected, the detection comprises battery electric quantity detection and charging condition detection, and when the current battery electric quantity of the power supply battery is higher than a protection threshold value or the power supply battery is in a condition that the power supply battery cannot be charged, the duty ratio of the PWM control signal is adjusted to be minimum. If the difference value is not the above condition, judging the difference value obtained by subtracting the charging current (second charging current) from the set threshold value, and if the difference value is larger than zero, reducing the duty ratio of the PWM control signal; on the contrary, if the duty ratio is smaller than zero, the duty ratio of the PWM control signal is increased, and when the duty ratio is increased to 100%, the entire feedback energy is recovered by the power supply battery, and at this time, the second charging current is equal to the first charging current. The duty cycle of the PWM control signal is determined by this logic flow.
In one embodiment of the present invention, the dissipation uses a second controllable switch to control the connection between the first charging current and the electric energy dissipation device; the second controllable switch is controlled by an inverted signal of the chopping control signal and is opposite to the opening and closing state of the first controllable switch. The second controllable switch here is also preferably a power switch IGBT and the power dissipation device is preferably a resistor. When the electric energy dissipation device is directly connected to the circuit, the first charging current is dissipated all the time, which is not beneficial to energy recycling. In this embodiment, the second controllable switch is used to dissipate the redundant electric energy only when needed, and the second controllable switch is opposite to the first controllable switch in the on-off state, that is, the first charging current is divided into two parts, one part is converted into the second charging current, and the other current is connected to the electric energy dissipation device. In a specific implementation, the first controllable switch and the second controllable switch may also be integrated into a selection switch, and the selection switch is selectively directly connected between the converting branch and the dissipating branch to select a flow direction of the first charging current.
In one embodiment provided by the present invention, the method further comprises: and the first charging current flowing into the first controllable switch when the first controllable switch is closed is stored, and the energy storage is utilized to supply energy to the inductor when the first controllable switch is opened. As mentioned above, the second charging current is formed by a series of pulse currents after the series of pulse currents pass through the inductor and the first controllable switch is frequently switched on and off, so as to prevent the impact current from forming and affecting the power supply battery, and therefore, a capacitor is added to ensure the continuity of the feedback charging current. Simultaneously, the capacitor has an energy storage function, and can supply energy to the inductor when the first controllable switch is switched off, so that the continuity of the second charging current is further ensured.
Fig. 3 is a schematic structural diagram of an energy feedback charging current limiting apparatus according to an embodiment of the present invention, as shown in fig. 3, in an embodiment of the present invention, there is further provided an energy feedback charging current limiting apparatus disposed between a power supply battery of an electric drive system and an electric machine, the electric machine operating in an electric state or an energy feedback state, the apparatus including: the determining component is used for determining that the motor works in an energy feedback state; the conversion component is used for converting the first charging current fed back by the motor into a second charging current after chopping and charging the power supply battery; control means for determining the chopped chopping control signal based on the second charging current; and a dissipating component for dissipating the current converted from the first charging current to the second charging current. When the motor works in an electric state, the power supply battery directly supplies power to the motor, and the device for feeding back energy to limit the charging current cannot play a role. When the motor works in an energy feedback state, the role of the motor is converted from consumed electric energy to generated electric energy, and output current to the power supply side is generated, wherein the current at the moment is first charging current. The current is converted through chopping, namely the current is processed and then is charged to the power supply battery, and the charging current is the second charging current. The conversion component and the control component can control the first charging current fed back by the motor to be stable and supply the charging current of the power supply battery, so that the problems of overlarge charging current of the power supply battery and low energy recovery efficiency are effectively solved.
Fig. 4 is a circuit implementation structure diagram of an apparatus for limiting an energy feedback charging current according to an embodiment of the present invention, and as shown in fig. 4, the motor operates in an electromotive state or an energy feedback state, which corresponds to different operating states of the diode D and the switch G3 in fig. 4. When the motor works in the electric state, the diode D is in the forward conducting state, the electric energy of the power supply battery provides the electric energy required by driving to the motor through the diode D and the driver, and the switch G3 is in the off state, so that the method of energy feedback charging current limitation is not required to be performed, and the current fed back by the motor is not required. When the motor determined by the determining component works in the energy feedback state, the diode D is in the reverse open circuit state, the switch G3 is in the closed state, and the first charging current fed back from the motor reaches the power supply battery through the converting component to charge the power supply battery. The roles of diode D and switch G3 are described below, respectively: a diode D: when the charging current of feedback is directly to power supply battery charging, too big electric current can cause the damage of power supply battery, and the anodal transposition diode D of place power supply battery has avoided directly filling the power supply battery harm that brings, and when power supply battery supplied power to the motor, the repayment electric current of restriction driver caused the harm switch to the battery simultaneously. G3: when the power supply battery supplies power, energy is prevented from being consumed on the inductor and the capacitor, the motor is disconnected in the electric state, and the motor is closed in the energy feedback state, and a relay and the like can be adopted for implementation.
The conversion member includes: a first controllable switch for chopping the first charging current into a series of pulsed currents; and the inductor is used for smoothing the series of pulse currents to obtain the second charging current. When the first controllable switch G1 is turned on, a part of the first charging current charges the battery through the inductor L and a part charges the capacitor C; when the first controllable switch G1 is turned off, the capacitor C releases the follow current of the electric energy, and the continuity of the charging current is ensured.
The control part includes: the current sampling circuit is used for acquiring the coupling current of the second charging current and determining the measured value of the second charging current; a logic controller for determining a waveform parameter of the chopping control signal based on stored control logic and measurement values, and a waveform generator for generating the chopping control signal according to the waveform parameter. The current sampling circuit can adopt mutual inductance sampling, series voltage division or Hall sensing and the like, the logic controller comprises a single chip microcomputer, a processor or a PLC and the like, and the waveform generator preferably adopts a UC3879 chip and other PWM chips and the like. Wherein the control logic stored in the logic controller is as described in the foregoing method and will not be repeated here.
In one embodiment of the present invention, the apparatus further comprises: and one end of the capacitor is connected with the connecting end of the inductor and the first controllable switch, and the other end of the capacitor is connected with the negative electrode of the power supply battery. Since the first controllable switch G1 is frequently turned on and off, in order to prevent the impact current from forming and affecting the battery, a capacitor C is added, and the connection mode is shown in fig. 4, which has a certain filtering function. And the capacitor C also has the function of energy storage, and when the first controllable switch G1 is switched off, the capacitor C can release electric energy for continuous flow, so that the continuity of the charging current is ensured.
The device further comprises an electric energy dissipation branch, wherein the electric energy dissipation branch receives the input of the first charging current; the electric energy dissipation branch comprises: a second controllable switch for controlling the communication of the first charging current with a dissipative component; the second controllable switch is controlled by an inverted signal of the chopping control signal and is opposite to the opening and closing state of the first controllable switch; and a dissipating component for dissipating the input current. Specifically, the second controllable switch G2 is an IGBT, can be driven by a PWM signal, and when the motor is in an electric state, G1 and G2 are all turned off, and the power supply battery supplies power to the motor; when the motor is in a feedback state, the on-off states of G1 and G2 are complementary, so that the shunt control of the first charging current is realized, and the purpose of limiting the overlarge feedback charging current is achieved. And the resistor R is used for consuming redundant energy by using the resistor when the motor works in a power generation state. Here, the control signals of G1 and G2 may be two switching control signals with opposite phases directly output by the control unit, or another switching control signal may be obtained by passing one switching control signal through an inverter such as a not gate or a CMOS inverter.
In order to further verify the technical effect of the embodiment of the invention, a hardware circuit of the device provided by the scheme is built in MATLAB/Simulink, and the energy feedback process is simulated through simulation verification as follows:
when the motor is in an energy feedback state, alternating current induced electromotive force is generated and converted into direct current through the conversion of driver rectification to charge a power supply battery, so that feedback charging current is simulated by a voltage source, the switch G3 is always in a closed state and can be omitted, the structures and positions of other components are unchanged, G1 and G2 are in an open-close complementary state, PWM driving is adopted, and a simulation effect diagram is obtained through operation simulation.
Fig. 5 is a simulation effect diagram of an apparatus for limiting an energy feedback charging current according to an embodiment of the present invention, and as shown in fig. 5, the control concept in this diagram is: by controlling the PWM duty cycle, the energy feedback charging current (i.e., the second charging current) is maintained near the set limit threshold. From top to bottom, do in proper order: energy feedback charging voltage, PWM control signal and feedback charging current (namely first charging current) and setting limit threshold and average resistance current.
The simulated feedback charging voltage, i.e. the voltage corresponding to the first charging current, fluctuates at about 53V ± 4V, which conforms to the actual working condition of energy feedback. The 4-segment simulation operating condition analysis shown in FIG. 5 is taken for illustration.
A first time period: the energy feedback charging voltage is continuously increased, the feedback charging current is smaller than a set limit threshold value, and the PWM duty ratio is increased, so that the feedback charging current is increased to be close to the threshold value, most of electric energy is fed back to the battery, and a small part of electric energy is consumed on the resistor.
A second time period: at this stage, the charging current is already close to the threshold value, in order to maintain the limit of the charging current, the PWM duty ratio and the change of the braking induced electromotive force are changed in inverse proportion, and the energy consumed on the resistor is consistent with the change of the induced electromotive force.
A third time period: the induced electromotive force is in a low peak, the PWM duty ratio is adjusted to be maximum, all electric energy is fed back for charging, and no energy is consumed on the resistor.
And a fourth time period: setting the threshold change, the regenerative charging current control strategy can continue to remain near the threshold.
From the above analysis, the device and method provided by the present invention can effectively limit the feedback current, and avoid the damage of the battery caused by the excessive feedback charging current.
The method and the device provided by the embodiment of the invention are used on an electric drive system powered by a battery, and the power switch can be quickly switched on and off due to the fact that the number of conversion stages is small, and can quickly recover energy and shorten the braking distance during high-speed braking.
Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solutions of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and the simple modifications all belong to the protection scope of the embodiments of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention do not describe every possible combination.
Those skilled in the art will understand that all or part of the steps in the method according to the above embodiments may be implemented by a program, which is stored in a storage medium and includes several instructions to enable a single chip, a chip, or a processor (processor) to execute all or part of the steps in the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In addition, any combination of different implementation manners of the embodiments of the present invention can be performed, and the embodiments of the present invention should be considered as disclosed in the embodiments of the present invention as long as the combination does not depart from the idea of the embodiments of the present invention.
Claims (13)
1. A method of energy regenerative charging current limiting for energy recovery in an electric drive system including a power supply battery and an electric machine, the electric machine operating in an motoring state or an energy regenerative state, the method comprising:
determining that the motor works in an energy feedback state;
the first charging current fed back by the motor is converted into a second charging current after being chopped, and the second charging current is used for charging the power supply battery;
determining the chopped chopping control signal based on the second charging current;
and simultaneously dissipating the current converted from the first charging current to the second charging current.
2. The method of claim 1, wherein the step of chopping the first charging current fed back from the motor into a second charging current comprises:
chopping the first charging current into a series of pulse currents by using a first controllable switch, and smoothing the series of pulse currents by using an inductor to obtain a second charging current;
the chopping control signal is used for controlling the opening and closing of the first controllable switch.
3. The method of claim 2, wherein the dissipating comprises:
controlling the communication of the first charging current and the electric energy dissipation device by adopting a second controllable switch; the second controllable switch is opposite to the first controllable switch in opening and closing states.
4. The method of claim 2, wherein the chopping control signal is a PWM control signal; the determining the chopped chopping control signal includes: determining a duty cycle of the PWM control signal.
5. The method of claim 4, wherein determining the chopped chopping control signal based on the second charging current comprises:
judging whether the second charging current is larger than a set current threshold value or not;
if so, reducing the duty ratio of the PWM control signal output to the first controllable switch based on the current PWM control signal; otherwise, increasing the duty cycle of the PWM control signal output to the first controllable switch based on the current PWM control signal.
6. The method of claim 5, wherein the duty cycle of the PWM control signal is preset to a minimum value;
and determining that the current battery power of the power supply battery is higher than a protection threshold value or under the condition that the power supply battery cannot be charged, and adjusting the duty ratio of the PWM control signal to be the minimum duty ratio.
7. The method of any of claims 2-6, further comprising:
and the first charging current flowing into the first controllable switch when the first controllable switch is closed is stored, and the energy storage is utilized to supply energy to the inductor when the first controllable switch is opened.
8. An energy feedback charging current limiting device disposed between a power supply battery and an electric motor of an electric drive system, the electric motor operating in an electric or energy feedback state, the device comprising:
the determining component is used for determining that the motor works in an energy feedback state;
the conversion component is used for converting the first charging current fed back by the motor into a second charging current after chopping and charging the power supply battery;
control means for determining the chopped chopping control signal based on the second charging current; and
and the dissipation component is used for dissipating the current converted into the second charging current in the first charging current.
9. The apparatus of claim 8, wherein the converting means comprises:
a first controllable switch for chopping the first charging current into a series of pulsed currents; and
and the inductor is used for smoothing the series of pulse currents to obtain the second charging current.
10. The apparatus of claim 8, wherein the control unit comprises:
the current sampling circuit is used for acquiring the coupling current of the second charging current and determining the measured value of the second charging current;
a logic controller for determining waveform parameters of the chopped control signal based on stored control logic and measurements; and
and the waveform generator is used for generating the chopping control signal according to the waveform parameters.
11. The apparatus of claim 10, wherein the chopping control signal is a PWM control signal, and the control logic comprises:
determining that the second charging current is greater than a set current threshold, and reducing a duty cycle of a PWM control signal output to the first controllable switch based on a current PWM control signal;
determining that the second charging current is less than or equal to the set current threshold, and increasing the duty ratio of the PWM control signal output to the first controllable switch based on the current PWM control signal;
and determining that the current battery power of the power supply battery is higher than a protection threshold value or under the condition that the power supply battery cannot be charged, and adjusting the duty ratio of the PWM control signal to be a preset minimum duty ratio value.
12. The apparatus of claim 9, further comprising:
and one end of the capacitor is connected with the connection end of the inductor and the first controllable switch, and the other end of the capacitor is connected with the negative electrode of the power supply battery.
13. An arrangement for energy regenerative charging current limiting according to any of claims 9 to 12, characterized in that the dissipating means receives the current to be dissipated via a second controllable switch;
the second controllable switch is used for controlling the communication of the first charging current and the dissipation component; and when the motor works in an energy feedback state, the second controllable switch is opposite to the opening and closing state of the first controllable switch.
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| CN202011323160.1A CN112436581A (en) | 2020-11-23 | 2020-11-23 | Method and device for limiting energy feedback charging current |
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| CN202011323160.1A CN112436581A (en) | 2020-11-23 | 2020-11-23 | Method and device for limiting energy feedback charging current |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114865754A (en) * | 2022-07-06 | 2022-08-05 | 荣耀终端有限公司 | Charging circuit, charging chip and electronic equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114865754A (en) * | 2022-07-06 | 2022-08-05 | 荣耀终端有限公司 | Charging circuit, charging chip and electronic equipment |
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