CN114679042A - Active discharge method, device, storage medium and motor electric control system - Google Patents

Active discharge method, device, storage medium and motor electric control system Download PDF

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Publication number
CN114679042A
CN114679042A CN202210417450.5A CN202210417450A CN114679042A CN 114679042 A CN114679042 A CN 114679042A CN 202210417450 A CN202210417450 A CN 202210417450A CN 114679042 A CN114679042 A CN 114679042A
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China
Prior art keywords
direct current
loss value
switching
converter
preset
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CN202210417450.5A
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Chinese (zh)
Inventor
吴鸿达
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Suzhou Huichuan United Power System Co Ltd
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Suzhou Huichuan United Power System Co Ltd
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Priority to CN202210417450.5A priority Critical patent/CN114679042A/en
Publication of CN114679042A publication Critical patent/CN114679042A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses an active discharge method, an active discharge device, a storage medium and a motor electric control system, wherein the active discharge method controls a direct current converter to operate at a preset duty ratio and increases current ripples to a preset current value when the motor electric control system receives an active discharge instruction; and maintaining the switching loss value of the direct current converter to be kept at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor. According to the invention, the voltage of the bus capacitor is actively released by controlling the direct current converter to operate at the preset duty ratio and maintaining the switching loss value of the direct current converter to be kept at the target loss value corresponding to the preset current value, so that the energy stored in the motor electric control system is rapidly released without adding an additional discharge circuit.

Description

Active discharge method, device, storage medium and motor electric control system
Technical Field
The invention relates to the technical field of discharge, in particular to an active discharge method, an active discharge device, a storage medium and a motor electric control system.
Background
With the continuous expansion of new energy automobile market, high power density, low cost and high endurance mileage are the major trends of automobile development. In order to improve the efficiency and the driving capability of the motor and fully utilize the voltage of the battery, a direct current converter is additionally arranged between the power battery and the motor driving inverter by the motor electric control system. When the voltage of the battery is low, the direct current converter can stably control the output voltage, so that the system is in the optimal working condition, and the motor can effectively utilize the bus voltage and exert the maximum capacity at any time.
Due to safety requirements, when a new energy automobile is powered off or crashes, energy stored in a motor electric control system needs to be discharged rapidly, namely, active discharge is carried out, and the voltage is required to be reduced to be below the safe voltage within a short time generally. The existing discharge mainly depends on a discharge circuit formed by adding additional elements to discharge, and the cost of a motor electric control system is increased to a certain extent.
The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.
Disclosure of Invention
The invention mainly aims to provide an active discharging method, an active discharging device, a storage medium and a motor electric control system, and aims to solve the technical problem that the cost of the motor electric control system is increased in the process of rapidly discharging stored energy in the prior art.
In order to achieve the above object, the present invention provides an active discharge method applied to an electric motor control system including a dc converter;
wherein the active discharge method comprises:
when the motor electric control system receives an active discharge instruction, controlling the direct current converter to operate at a preset duty ratio and increasing the current ripple to a preset current value;
and maintaining the switching loss value of the direct current converter to be kept at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor.
Optionally, before the step of controlling the dc converter to operate at a preset duty ratio and increasing the current ripple to a preset current value when the motor electronic control system receives the active discharge instruction, the method further includes:
acquiring operation parameters of the motor electric control system;
determining a first mapping relation between the output duty ratio of the direct current converter and a switching loss value according to the operation parameters;
and determining the preset duty ratio of the direct current converter according to the first mapping relation.
Optionally, the step of determining the preset duty ratio of the dc converter according to the first mapping relationship includes:
determining the output duty ratio of the direct current converter corresponding to the maximum switching loss value according to the first mapping relation;
and taking the output duty ratio corresponding to the maximum switching loss value as a preset duty ratio.
Optionally, the step of maintaining the switching loss value of the dc converter at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor includes:
adjusting the switching frequency of a switching tube in the direct current converter to a target switching frequency;
and driving a switching tube in the direct current converter according to the target switching frequency to maintain the switching loss value of the direct current converter to be kept at the target loss value, and actively releasing the voltage of the bus capacitor.
Optionally, before the step of adjusting the switching frequency of the switching tube in the dc converter to the target switching frequency, the method further includes:
acquiring a second mapping relation between the switching frequency and the switching loss value;
and determining a target switching frequency corresponding to the target loss value according to a second mapping relation between the switching frequency and the switching loss value.
Optionally, the step of obtaining a second mapping relationship between the switching frequency and the switching loss value includes:
acquiring a third mapping relation between the switching loss value and the discharge rate of a switching tube in the direct current converter;
acquiring a fourth mapping relation between the switching frequency and the discharge rate of a switching tube in the direct current converter;
and determining a second mapping relation between the switching frequency and the switching loss value according to the third mapping relation and the fourth mapping relation.
Optionally, the step of maintaining the switching loss value of the dc converter at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor further includes:
and when a preset discharge circuit is included in the motor electric control system, maintaining the switching loss value of the direct current converter at the target loss value and simultaneously controlling the preset discharge circuit to start to actively release the voltage of the bus capacitor.
In addition, to achieve the above object, the present invention also provides an active discharge device including:
the control module is used for controlling the direct current converter to operate at a preset duty ratio and increasing the current ripple to a preset current value when the motor electric control system receives an active discharge instruction;
and the discharging module is used for maintaining the switching loss value of the direct current converter to be kept at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor.
In addition, to achieve the above object, the present invention further provides a storage medium, wherein the storage medium stores an active discharging program, and the active discharging program implements the steps of the active discharging method when executed by a processor.
In addition, in order to achieve the above object, the present invention also provides an electric motor control system, including: the system comprises a direct current converter, an inverter, a motor and an electric control unit; the electric control unit is connected with the control end of a switch tube in the direct current converter, the direct current converter is respectively connected with a power supply of a motor electric control system, the energy storage element and the inverter, and the inverter is connected with the motor; the electronic control unit executes the steps of the active discharging method when in operation.
The invention provides an active discharge method, an active discharge device, a storage medium and a motor electric control system, wherein the active discharge method controls a direct current converter to operate at a preset duty ratio and increases current ripples to a preset current value when the motor electric control system receives an active discharge instruction; and maintaining the switching loss value of the direct current converter to be kept at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor. According to the invention, the voltage of the bus capacitor is actively released by controlling the direct current converter to operate at the preset duty ratio and maintaining the switching loss value of the direct current converter to be kept at the target loss value corresponding to the preset current value, so that the energy stored in the motor electric control system is rapidly released without adding an additional discharge circuit.
Drawings
Fig. 1 is a schematic structural diagram of a motor control system in a hardware operating environment according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart illustrating a first embodiment of an active discharging method according to the present invention;
FIG. 3 is a schematic flow chart illustrating an active discharging method according to a second embodiment of the present invention;
FIG. 4 is a first flowchart illustrating a third embodiment of an active discharging method according to the present invention;
FIG. 5 is a second flowchart illustrating an active discharging method according to a third embodiment of the present invention;
FIG. 6 is a schematic flow chart illustrating a fourth embodiment of an active discharging method according to the present invention;
fig. 7 is a block diagram of an active discharge device according to a first embodiment of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a motor electronic control system in a hardware operating environment according to an embodiment of the present invention.
As shown in fig. 1, the motor control system may include: the system comprises a direct current converter, an inverter, a motor MG, an energy storage element and an electric control unit; the electric control unit is connected with the control end of a switch tube in the direct current converter, the direct current converter is respectively connected with a power supply of a motor electric control system, the energy storage element and the inverter, and the inverter is connected with the motor. The electrically controlled elements are not shown in fig. 1.
Those skilled in the art will appreciate that the configuration shown in fig. 1 does not constitute a limitation of the electromechanical system and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components.
The steps that make it possible to implement the active discharge method are carried out when the electronic control unit is operating in fig. 1.
Based on the hardware structure, the embodiment of the active discharging method is provided.
Referring to fig. 2, fig. 2 is a schematic flow chart of a first embodiment of the active discharging method of the present invention, and the first embodiment of the active discharging method of the present invention is provided.
In a first embodiment, the active discharge method comprises the steps of:
step S10: when the motor electric control system receives an active discharge instruction, the direct current converter is controlled to operate at a preset duty ratio, and the current ripple is increased to a preset current value.
It should be understood that the execution main body of the present embodiment may be an electronic control unit that controls the dc converter in the motor electronic control system. The electric control unit can be a device composed of control elements such as a chip, a singlechip, an ARM and the like. In addition, the electronic control unit can also be hardware equipment such as a computer, a notebook computer and the like.
It should be understood that, during the normal operation of the electric vehicle, the electric motor of the vehicle needs to be powered by the electric control system of the electric motor, so that the electric motor can work normally to provide enough power for the vehicle. When the vehicle is powered off or crashes, the connection between the power supply batteries of the motor and the vehicle motor needs to be disconnected, certain stored energy can exist in an energy storage element inside the motor electric control system at the moment, the stored energy needs to be released as soon as possible, and potential safety hazards are avoided.
Referring to fig. 1, it should be noted that the dc converter may be composed of an inductor and a certain number of switching tubes, and in fig. 1, one inductor is combined with two switching tubes to form the dc converter. A dc converter is a power electronic device that converts dc electrical energy into voltage or current-controllable dc electrical energy required by a load. The constant direct current voltage is chopped into a series of pulse voltages by the fast on-off control of an internal switching tube, the pulse width of the pulse series is changed by controlling the change of the duty ratio so as to realize the adjustment of the average value of the output voltage, and the adjusted average value of the voltage is filtered by a filter so as to obtain the direct current electric energy with controllable current or voltage on a controlled load. The output duty cycle is an effective duty cycle output by the electronic control unit for controlling the dc converter. When the output duty ratio is in an effective range, the direct current converter can normally work according to a signal output by the electric control unit; and in the invalid range of the output duty ratio, the direct current converter keeps the cut-off state. The preset duty ratio refers to a preset duty ratio for controlling the internal switching tube of the direct current converter to be normally switched on or switched off within a pulse period range. The preset duty cycle may be within a threshold range of an output duty cycle of a duty cycle, but may of course be a specific value. For example, when the preset duty ratio is 50%, when the electronic control unit outputs a control signal, in an output period of the control signal, the dc converter is in a normal operating state in the whole period, but the first switching tube and the second switching tube in the dc variation period are in a conducting state in a half period, and the first switching tube and the second switching tube are not conducted at the same time.
In a specific implementation, when the vehicle is powered off or in a collision, the electronic control unit can output a control signal with a constant duty ratio to the direct current converter, so that the output duty ratio of the direct current converter is adjusted. When implemented in this manner, the duty cycle of the control signal should be the same as the preset duty cycle. Of course, the electronic control unit can also output a control signal with a higher duty ratio, and then the on-off state of a switching tube in the direct current converter is controlled by other modes to adjust the output duty ratio of the direct current converter to the preset duty ratio.
It should be understood that, referring to fig. 1, when the contactor and the motor are both open, a certain amount of energy is released through the inductance in the dc converter only by the energy storage elements, i.e., the two capacitors, and the average current value through the inductance in the dc converter inside the motor electronic control system is close to 0 at this time. The switching loss includes an on loss and an off loss, and actually refers to a loss generated when the switching states of the first switching tube Q1 and the second switching tube Q2 are switched at the time when the current is at the positive peak value and the negative peak value, the larger the peak current is, the higher the loss is, the higher the on loss is positively correlated with the magnitude of the instantaneous current, and the larger the instantaneous current is, the higher the loss is.
The current ripple is a current value that fluctuates on both sides of the current average value. Due to the complementary on and off state changes of the two switching tubes, a certain current ripple is formed at two ends of the inductor. The current ripple is mainly formed by discharge of a capacitor, and the specific value of the current ripple fluctuates on both sides of the current value 0. Referring to fig. 1, a charge-discharge cycle of a capacitor includes four processes: the first process is that the first switch tube Q1 is closed and the second switch tube Q2 is opened, current flows through the body diode in the first switch tube Q1 from left to right, at the moment, the first capacitor C1 discharges the second capacitor C2 for charging, and the instantaneous current value is reduced from the peak value to 0; the second process is that the first switch tube Q1 is closed, the second switch tube Q2 is opened, current flows through the first switch tube Q1 from right to left, the first capacitor C1 charges the second capacitor C2 to discharge, and the instantaneous current value is increased from 0 to the peak value; the third process is that the first switch tube Q1 is disconnected, the second switch tube Q2 is closed, current flows through the body diode of the second switch tube Q2 from right to left, the first capacitor C1 charges the second capacitor C2 without charging and discharging, and the instantaneous current value is reduced to 0 from the peak value; the fourth process is that the first switch tube Q1 is opened and the second switch tube Q2 is closed, current flows through the second switch tube Q2 from left to right, the first capacitor C1 discharges the second capacitor C2 without charging and discharging, and the instantaneous current value is increased from 0 to the peak value.
In a specific implementation, the electric control device can continuously control the on and off states of a switching tube in the direct current converter to control the discharge of the energy storage element in a certain period. Therefore, current ripples can be formed in the motor electric control system in the on-off state of a switching tube of the direct current converter in the motor electric control system.
Step S20: and maintaining the switching loss value of the direct current converter to be kept at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor.
It will be appreciated that since the power supply of the motor control system and the motor are simultaneously off, the current through the dc converter is close to 0. The energy stored in the energy storage element does not generate excessive current and thus excessive heat to cause a safety event. Therefore, in this embodiment, when the switching tube in the dc converter is turned on, turned off, and continuously turned on, the energy stored in the energy storage element can be actively released by directly using the heat generated by the turn-on loss, the turn-off loss, and the continuous turn-on loss of the switching tube.
In a first embodiment, an active discharge method is provided, which adjusts an output duty ratio of the dc converter to a preset duty ratio when a vehicle is powered off or in a collision; controlling the direct current converter to operate at the preset duty ratio so that the electric quantity stored in the motor electric control system forms current ripples; and actively releasing the current ripple through the direct current converter. In the embodiment, the direct current converter is controlled to operate at the preset duty ratio, the switching loss value of the direct current converter is maintained to be kept at the target loss value corresponding to the preset current value, and the voltage of the bus capacitor is actively released, so that the energy stored in the motor electric control system is quickly released without adding an additional discharge circuit.
Referring to fig. 3, fig. 3 is a schematic flow chart of a second embodiment of the active discharge method of the present invention, which is provided based on the first embodiment shown in fig. 2.
In the second embodiment, before the step S10, the method further includes:
step S101: and acquiring the operation parameters of the motor electric control system.
It should be appreciated that the discharge rate may be increased by increasing the current value of the current ripple when releasing parameters within the electric motor control system. The larger the current value of the current ripple, the faster the rate of energy released by the energy storage element within the motor electrical control system.
It should be noted that the operation parameter refers to a parameter of operation of each element in the motor electric control system in a normal power supply or discharge state of the electric control system. The motor electrical control parameters may include: the bus voltage, the switching frequency of the switching tube, the inductive reactance, the working efficiency of the inverter and the like. The specific required operation parameters are closely related to the constituent elements in the motor electric control system, and the operation parameters required to be obtained corresponding to different constituent elements are different. Taking fig. 1 as an example, in fig. 1, the operation parameter may be a bus voltage of the motor electronic control system in a normal operating state, a power supply voltage provided by a power supply battery, an inductive reactance of an inductor, a switching frequency of a switching tube, and the like.
In specific implementation, the electric control unit can acquire parameters such as voltage and current through a sensor connected with the motor electric control system, certainly can also acquire the voltage at two ends of the inductor and the current passing through the inductor, and calculates the inductive reactance of the inductor according to the acquired voltage value and current value. Because the switching state of the switching tube is directly related to the control signal output by the electronic control unit, the switching frequency of the switching tube can be directly determined according to the control signal output by the electronic control unit.
Step S102: and determining a first mapping relation between the output duty ratio of the direct current converter and the switching loss value according to the operation parameters.
It should be understood that a certain mapping relationship exists between the output duty ratio of the dc converter and the current value of the switching loss value, and the specific current value of the current ripple generated in the motor electronic control system is different due to different output duty ratios of the dc converter, so that the switching loss value is different. The mapping relation between the output duty ratio of the direct current converter and the current ripple generated in the motor electric control system can be determined according to the specific operation state of the motor electric control system. Taking the working state of the electric control system of the motor in fig. 1 as an example, the specific current value Δ I of the current ripple is (U)dc-Ubat)*D/(L*f)＝UdcD (1-D)/(L f), wherein UdcIs the voltage of a bus in an electric control system of the motor, UbatFor electric control of electric motorsThe power supply voltage provided by a power supply battery of the system, D is the output duty ratio of the direct current converter, f is the switching frequency, and L is the inductance value. In fig. 1, the above formula is a mapping relation between the output duty ratio of the dc converter and the current ripple generated in the motor electronic control system. Then, a first mapping relation between the output duty ratio and the switching loss value can be determined according to the relation between the current ripple and the switching loss value.
Step S103: and determining the preset duty ratio of the direct current converter according to the first mapping relation.
It should be understood that, when determining the mapping relationship between the output duty cycle of the dc converter and the current ripple in the motor electronic control system, the preset duty cycle of the dc converter may be directly determined according to the first mapping relationship and the required current ripple, where the preset duty cycle corresponds to the required switching loss value.
The step S103 further includes:
step S1031: and determining the output duty ratio of the direct current converter corresponding to the maximum switching loss value according to the first mapping relation.
It should be noted that, the larger the current value of the current ripple, the larger the corresponding switching loss value, the faster the discharge rate of the energy storage element, and the higher the efficiency. Therefore, when the energy stored in the energy storage element of the motor electric control system is released, the output duty ratio of the direct current converter can be adjusted, so that the current ripple generated in the motor electric control system is adjusted, and the adjustment of the switching loss value is realized.
It should be understood that, in order to ensure the discharge efficiency of the motor electronic control system, the maximum value corresponding to the current ripple in the motor electronic control system may be determined according to the mapping relationship. As can be seen from the above formula, the maximum value of the current ripple is related to the voltage of the bus, the output duty cycle of the dc converter, the switching frequency in the dc converter, and the inductance and inductance. In a stable working system, the maximum value, the voltage of a bus, the switching frequency in the direct current converter and the inductance are fixed values, and the output duty ratio of the direct current converter can be directly controlled according to the electric control unit. According to the formula corresponding to the mapping relationship, the output duty ratio of the direct current converter and the current ripple are in a unitary quadratic conversion relationship. When the current ripple is adjusted, the output duty cycle of the dc converter can be directly determined according to the required current ripple, and at this time, the output duty cycle is the output duty cycle corresponding to the maximum switching loss value.
Step S1032: and taking the output duty ratio corresponding to the maximum switching loss value as a preset duty ratio.
It should be understood that, when the energy stored in the motor electronic control system needs to be released at the fastest rate, the corresponding preset duty ratio may be directly obtained according to the first mapping relationship, and then the electronic control unit adjusts the output duty ratio of the dc converter to the preset duty ratio, and the energy release process in the first embodiment is implemented, which is not described herein again.
In a second embodiment, an active discharge method is provided, in which an output duty cycle of a dc converter is adjusted to a preset duty cycle by acquiring an operation parameter of a motor electronic control system, and determining a relationship between the output duty cycle of the dc converter and a switching loss value according to the operation parameter of the motor electronic control system; controlling the direct current converter to operate at the preset duty ratio so that the electric quantity stored in the motor electric control system forms current ripples; and actively releasing the current ripple through the direct current converter. According to the invention, the preset duty ratio is determined through the first mapping relation, the direct current converter is controlled to operate at the preset duty ratio, and the direct current converter is utilized to actively release the current ripple, so that the energy stored in the motor electric control system is quickly released without adding an additional discharge circuit.
Referring to fig. 4 and 5, fig. 4 is a first flowchart of a third embodiment of the active discharge method of the present invention, and the third embodiment of the active discharge method of the present invention is proposed based on the first embodiment shown in fig. 2 and the second embodiment shown in fig. 3.
In the third embodiment, the step S20 may include:
step S21: and adjusting the switching frequency of a switching tube in the direct current converter to a target switching frequency.
It should be understood that the duration of operation of the switching tube in the dc converter is closely related to the amount of energy released, and the longer the switching tube is conducting during a cycle, the more energy released during the cycle. Therefore, in the process of releasing the stored energy of the motor electric control system, the discharge rate of the motor electric control system can be improved by adjusting the switching frequency of the switching tube in a complete discharge period.
In a specific implementation, the electronic control unit can adjust the switching frequency of the switching tube in the dc converter to the target switching frequency by the frequency of the control signal output to the switching tube in the dc converter. Of course, the adjustment can be performed in other ways, and is not limited in particular.
Step S22: and driving a switching tube in the direct current converter according to the target switching frequency to maintain the switching loss value of the direct current converter to be kept at the target loss value, and actively releasing the voltage of the bus capacitor.
It should be understood that after the switching frequency of the switching tube in the dc converter is increased, the energy release rate stored in the electric control system of the motor can be further increased, so that the active release of the current ripple at the target switching frequency after the adjusted switching frequency can increase the energy release rate.
Referring to fig. 5, in the third embodiment, the step S21 may be preceded by:
step S201: acquiring a second mapping relation between the switching frequency and the switching loss value;
it should be understood that, according to the first mapping relationship, the switching frequency may increase the number of times that the switching tube is turned on within a fixed time, so as to increase the switching loss and improve the release rate of the energy stored in the motor electronic control system, but the current value of the current ripple may be changed, so that the release rate of the energy stored in the motor electronic control system is reduced. Therefore, when the switching frequency of the switching tube is adjusted, a suitable target value should be selected between the switching frequency of the switching tube and the current value of the current ripple, so that the energy stored in the electric control system of the motor is released at the fastest rate.
It should be noted that the target switching frequency refers to a switching frequency at which the energy stored in the electric control system of the motor can be released at the fastest rate. In the specific acquisition process, the target switching frequency can be determined through a large number of operations according to the influence relationship of the switching frequency on the energy release, the influence relationship of the switching frequency on the current ripple, and the influence relationship between the current ripple and the energy release. In addition, considering the error and the calculation contingency, the target switching frequency can be determined by a model trained by a large number of samples.
Step S202: determining a target switching frequency corresponding to the target loss value according to a second mapping relation between the switching frequency and the switching loss value;
it should be understood that, as can be seen from the formula relationship in the first embodiment, there is a certain mapping relationship between the switching frequency and the current ripple, and in this embodiment, the mapping relationship between the switching frequency and the current ripple is taken as the second mapping relationship.
It should be noted that, in the case of determining the target switching frequency, the target current ripple corresponding to the target switching frequency may be determined according to the second mapping relationship between the switching frequency and the current ripple, and then the current ripple is adjusted to the target current ripple by adjusting the output duty ratio of the dc converter. The target current ripple is the regulated current ripple.
In specific implementation, the target current ripple may be determined first, then the target switching frequency is determined according to the target current ripple and the second mapping relationship between the switching frequency and the current ripple, and finally the switching frequency of the switching tube is adjusted according to the control signal output by the electronic control unit, which of course needs to adjust the current ripple to the target current ripple.
And driving a switching tube in the direct current converter to actively release the voltage of the bus capacitor according to the target switching frequency.
It should be understood that, under the condition that both the target current ripple and the target switching frequency are determined, the electronic control unit may directly control the switching tube in the dc converter to operate according to the output duty ratio corresponding to the target current ripple and the target switching frequency according to the output control signal, so as to safely release the energy stored in the motor electronic control system at the fastest rate.
Wherein, before the step S21, the method may further include:
step S2011: acquiring a third mapping relation between the switching loss value and the discharge rate of a switching tube in the direct current converter;
it should be noted that there is a certain mapping relationship between the switching loss value and the discharge rate of the switching tube in the dc converter. The larger the current ripple is, the larger the current passing through the switching tube is, the larger the switching loss value is, and at this time, the faster the discharge rate of the switching tube is, and in this embodiment, a mapping relationship between the switching loss value and the discharge rate of the switching tube in the dc converter is taken as a third mapping relationship. The third mapping relationship is related to specific operating parameters of the switching tube. Wherein the third mapping relationship may also be expressed as a mapping relationship between the current ripple and the discharge rate.
In specific implementation, the electronic control unit may obtain a third mapping relationship between the switching loss value and the discharge rate of the switching tube in the dc converter by testing the current passing through the switching tube and the corresponding discharge rate of the switching tube in the electrode electronic control system. In this embodiment, of course, the same switching tube may be used to perform an external test, and the test result is input to the controllable device, so as to obtain a third mapping relationship between the switching loss value and the discharge rate of the switching tube in the dc converter.
Step S2012: acquiring a fourth mapping relation between the switching frequency and the discharge rate of a switching tube in the direct current converter;
it should be noted that the switching frequency directly affects the time for the switching tube to discharge, and in a fixed time, the higher the switching frequency of the switching tube is, the more energy the switching tube releases in the fixed time corresponds to the higher the discharge rate. In the present embodiment, a mapping relationship between the switching frequency of the switching tube and the discharge rate of the switching tube in the dc converter is used as the fourth mapping relationship.
Step S2013: and determining the target switching frequency of a switching tube in the direct current converter according to the third mapping relation and the fourth mapping relation.
It should be understood that, in the case of determining the third mapping relationship between the ripple current and the discharge rate of the switching tube and also determining the fourth mapping relationship between the switching frequency and the discharge rate of the switching tube, the switching frequency and the current ripple may be continuously adjusted according to the third mapping relationship and the fourth mapping relationship until the target switching frequency or the target current ripple corresponding to the maximum discharge rate is obtained.
In a third embodiment, the output duty cycle of the dc converter is adjusted to obtain a corresponding current ripple, the switching frequency of the switching tube is adjusted, and the energy stored in the motor electronic control system is released through the switching tube in the dc converter according to the adjusted current ripple and the target switching frequency, so that the energy stored in the motor electronic control system is released at the fastest rate without adding an additional discharge circuit.
Referring to fig. 6, fig. 6 is a first flowchart illustrating an active discharge method according to a fourth embodiment of the present invention, which is proposed based on the first embodiment shown in fig. 2.
In this embodiment, the step S20 includes:
step S20': and when a preset discharge circuit is included in the motor electric control system, maintaining the switching loss value of the direct current converter at the target loss value and simultaneously controlling the preset discharge circuit to start to actively release the voltage of the bus capacitor.
It should be understood that, there may be a case where the energy release rate is slow when the energy stored in the electric motor control system is released by the active discharge method in the first embodiment, and at this time, if a preset discharge circuit is further included in the electric motor control system, the current ripple may be released simultaneously through the switch tube and the preset discharge circuit in the dc converter, so as to avoid a safety risk that the energy release is slow when a vehicle collides.
It should be noted that the preset discharge circuit may be a discharge circuit preset in the motor electric control system. Compared with the situation that the preset discharging circuit is not arranged in the first embodiment, the discharging cost is increased to a certain extent by arranging the preset discharging circuit, but the energy stored in the motor electric control system is released simultaneously through the preset discharging circuit and the switching tube in the direct current converter, so that the energy can be completely released at the fastest speed.
In a specific implementation, the electronic control unit can also detect the process of releasing energy stored in the motor electronic control system to determine whether the preset discharge circuit exists or not under the condition that a switching tube in the direct current converter is not used for discharging and under the condition that the vehicle is powered off or in a collision. When a preset discharge circuit is included in the motor electric control system, on one hand, the preset discharge circuit and a switch tube in the direct current converter are controlled to maintain the switching loss value of the direct current converter to be kept at the target loss value, and the energy stored in the motor electric control system is actively released, and on the other hand, the energy stored in the motor electric control system is released through the preset discharge circuit.
In this embodiment, when the preset discharge circuit is present in the motor electronic control system, the switch tube in the dc converter and the preset discharge circuit release the energy stored in the motor electronic control system at the same time, so as to further increase the release rate of the energy stored in the motor electronic control system.
In addition, an embodiment of the present invention further provides a storage medium, where the storage medium stores an active discharging program, and the active discharging program, when executed by a processor, implements the steps of the active discharging method as described above.
In addition, referring to fig. 7, an active discharge device according to an embodiment of the present invention is further provided, and in this embodiment, the active discharge device includes:
the control module 10 is configured to control the dc converter to operate at a preset duty ratio and increase the current ripple to a preset current value when the motor electronic control system receives an active discharge instruction;
and the discharging module 20 is configured to maintain the switching loss value of the dc converter at a target loss value corresponding to a preset current value, so as to actively release the voltage of the bus capacitor.
In a first embodiment, an active discharge device is provided, which controls a dc converter to operate at a preset duty ratio and increase a current ripple to a preset current value when an active discharge instruction is received by a motor electronic control system through a control module 10; the discharging module 20 maintains the switching loss value of the dc converter at a target loss value corresponding to a preset current value, so as to actively release the voltage of the bus capacitor. In the embodiment, the direct current converter is controlled to operate at the preset duty ratio, the switching loss value of the direct current converter is maintained to be kept at the target loss value corresponding to the preset current value, and the voltage of the bus capacitor is actively released, so that the energy stored in the motor electric control system is quickly released without adding an additional discharge circuit.
In an embodiment, the control module 10 is further configured to obtain an operation parameter of the motor electric control system; determining a first mapping relation between the output duty ratio of the direct current converter and a switching loss value according to the operation parameters; and determining the preset duty ratio of the direct current converter according to the first mapping relation.
In an embodiment, the control module 10 is further configured to determine an output duty cycle of the dc converter corresponding to the maximum switching loss value according to the first mapping relationship; and taking the output duty ratio corresponding to the maximum switching loss value as a preset duty ratio.
In an embodiment, the discharging module 20 is further configured to adjust a switching frequency of a switching tube in the dc converter to a target switching frequency; and driving a switching tube in the direct current converter according to the target switching frequency to maintain the switching loss value of the direct current converter to be kept at the target loss value, and actively releasing the voltage of the bus capacitor.
In an embodiment, the discharging module 20 is further configured to obtain a second mapping relationship between the switching frequency and the switching loss value; and determining a target switching frequency corresponding to the target loss value according to a second mapping relation between the switching frequency and the switching loss value.
In an embodiment, the control module 20 is further configured to obtain a third mapping relationship between the switching loss value and a discharge rate of a switching tube in the dc converter; acquiring a fourth mapping relation between the switching frequency and the discharge rate of a switching tube in the direct current converter; and determining the target switching frequency of a switching tube in the direct current converter according to the third mapping relation and the fourth mapping relation.
In an embodiment, the control module 20 is further configured to, when a preset discharge circuit is included in the motor electronic control system, maintain the switching loss value of the dc converter at the target loss value, and simultaneously control the preset discharge circuit to start to actively release the voltage of the bus capacitor.
Other embodiments or specific implementations of the active discharge device according to the present invention may refer to the above method embodiments, and are not described herein again.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments. In the unit claims enumerating several motor control systems, several of these motor control systems may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order, but rather the words first, second, third, etc. are to be interpreted as names.
Through the description of the foregoing embodiments, it is clear to those skilled in the art that the method of the foregoing embodiments may be implemented by software plus a necessary general hardware platform, and certainly may also be implemented by hardware, but in many cases, the former is a better implementation. Based on such understanding, the technical solutions of the present invention or portions thereof that contribute to the prior art may be embodied in the form of a software product, where the computer software product is stored in a storage medium (e.g., a Read Only Memory (ROM)/Random Access Memory (RAM), a magnetic disk, an optical disk), and includes several instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. An active discharge method is characterized in that the active discharge method is applied to a motor electric control system comprising a direct current converter;
wherein the active discharge method comprises:
when the motor electric control system receives an active discharge instruction, controlling the direct current converter to operate at a preset duty ratio and increasing the current ripple to a preset current value;
and maintaining the switching loss value of the direct current converter at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor.
2. The active discharge method of claim 1, wherein before the step of controlling the dc converter to operate at a preset duty cycle and increase the current ripple to a preset current value when the motor control system receives the active discharge command, the method further comprises:
acquiring operation parameters of the motor electric control system;
determining a first mapping relation between the output duty ratio of the direct current converter and a switching loss value according to the operation parameters;
and determining the preset duty ratio of the direct current converter according to the first mapping relation.
3. The active discharge method of claim 2, wherein the step of determining the preset duty cycle of the dc converter according to the first mapping relationship comprises:
determining the output duty ratio of the direct current converter corresponding to the maximum switching loss value according to the first mapping relation;
and taking the output duty ratio corresponding to the maximum switching loss value as a preset duty ratio.
4. The active discharging method according to claim 1, wherein the step of maintaining the switching loss value of the dc converter at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor comprises:
adjusting the switching frequency of a switching tube in the direct current converter to a target switching frequency;
and driving a switching tube in the direct current converter according to the target switching frequency to maintain the switching loss value of the direct current converter to be kept at the target loss value, and actively releasing the voltage of the bus capacitor.
5. The active discharge method of claim 4, wherein the step of adjusting the switching frequency of the switching tube in the dc converter to the target switching frequency is preceded by the step of:
acquiring a second mapping relation between the switching frequency and the switching loss value;
and determining a target switching frequency corresponding to the target loss value according to a second mapping relation between the switching frequency and the switching loss value.
6. The active discharge method of claim 5 wherein the step of adjusting the switching frequency of the switching tube in the dc converter to a target switching frequency is preceded by the step of:
acquiring a third mapping relation between the switching loss value and the discharge rate of a switching tube in the direct current converter;
acquiring a fourth mapping relation between the switching frequency and the discharge rate of a switching tube in the direct current converter;
and determining the target switching frequency of a switching tube in the direct current converter according to the third mapping relation and the fourth mapping relation.
7. The active discharge method of claim 1, wherein the step of maintaining the switching loss value of the dc converter at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor further comprises:
when a preset discharge circuit is included in the motor electric control system, the switching loss value of the direct current converter is maintained at the target loss value, and meanwhile the preset discharge circuit is controlled to start to actively release the voltage of the bus capacitor.
8. An active discharge device, comprising:
the control module is used for controlling the direct current converter to operate at a preset duty ratio and increasing the current ripple to a preset current value when the motor electric control system receives an active discharge instruction;
and the discharging module is used for maintaining the switching loss value of the direct current converter to be kept at a target loss value corresponding to a preset current value so as to actively release the voltage of the bus capacitor.
9. A storage medium having an active discharge program stored thereon, the active discharge program when executed by a processor implementing the steps of the active discharge method according to any one of claims 1 to 7.
10. An electric motor control system, comprising: the system comprises a direct current converter, an inverter, a motor, an energy storage element and an electric control unit; the electric control unit is connected with the control end of a switch tube in the direct current converter, the direct current converter is respectively connected with a power supply of a motor electric control system, the energy storage element and the inverter, and the inverter is connected with the motor; the electronic control unit is operative to perform the steps of the active discharge method as claimed in any one of claims 1 to 7.
CN202210417450.5A 2022-04-20 2022-04-20 Active discharge method, device, storage medium and motor electric control system Pending CN114679042A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210417450.5A CN114679042A (en) 2022-04-20 2022-04-20 Active discharge method, device, storage medium and motor electric control system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210417450.5A CN114679042A (en) 2022-04-20 2022-04-20 Active discharge method, device, storage medium and motor electric control system

Publications (1)

Publication Number Publication Date
CN114679042A true CN114679042A (en) 2022-06-28

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Country Status (1)

Country Link
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