Motor controller active discharge control method and related device
By controlling the bridge arm of the motor controller to switch between incomplete on and off states, and utilizing the losses of the power switching transistors to dissipate the energy of the bus capacitor, the problem of increased cost and area in the existing technology is solved, and safe and efficient bus capacitor discharge is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI LIXIANG AUTOMOBILE CO LTD
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-05
AI Technical Summary
Existing motor controller active discharge mechanisms release residual charge from bus capacitors via discharge resistors, increasing cost and printed circuit board area.
By controlling at least two phase bridge arms of the motor controller to periodically switch between incomplete on and off states, the switching and conduction losses of the power switching transistors are used to consume the energy of the bus capacitor, without the need to introduce additional hardware.
This saves on costs and printed circuit board area while ensuring safe and efficient release of residual charge from bus capacitors, avoiding potential dangers.
Smart Images
Figure CN122143654A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power electronics technology, and in particular to an active discharge control method and related device for a motor controller. Background Technology
[0002] In the drive system of an electric vehicle, the motor controller is responsible for converting the DC power output from the battery pack into AC power required to drive the motor, and controlling the motor's speed and torque to ensure that the vehicle can drive smoothly and efficiently.
[0003] During continuous vehicle operation, the bus capacitor in the motor controller efficiently accumulates energy to cope with voltage fluctuations and instantaneous energy demands that the motor may encounter during operation. However, after the power supply (i.e., the battery pack) is disconnected, the bus capacitor may still retain high-voltage charge due to its energy storage characteristics, which is extremely dangerous. The motor controller's active discharge mechanism automatically activates when the power is disconnected, switching to a dedicated discharge circuit to quickly and safely release the residual high-voltage charge in the bus capacitor to below a safe level.
[0004] The existing discharge circuit mainly converts the residual high voltage charge in the bus capacitor into heat energy through the discharge resistor, but the addition of the discharge resistor increases the cost and the area of the printed circuit board. Summary of the Invention
[0005] In view of the above problems, this application provides an active discharge control method and related device for a motor controller to save costs and printed circuit board area. The specific solution is as follows:
[0006] The first aspect of this application provides an active discharge control method for a motor controller, comprising:
[0007] In response to an active discharge command, at least two phase bridge arms of the motor controller simultaneously perform preset actions;
[0008] The execution of the preset action includes: the power switch of the first half of the bridge arm is fully turned on; the power switch of the second half of the bridge arm is periodically switched between incompletely turned on and off under the control of the PWM signal.
[0009] In one possible implementation, after at least two phase arms of the motor controller simultaneously perform a preset action, the system further includes:
[0010] Obtain the actual discharge slope k of the bus capacitor of the motor controller;
[0011] Determine whether the relays of the battery pack are stuck based on the actual discharge slope k; if so, report a discharge failure fault; if not, return to the step of obtaining the actual discharge slope k of the motor controller's bus capacitor until the discharge is completed.
[0012] In one possible implementation, determining whether the relay of the battery pack is stuck based on the actual discharge slope k includes:
[0013] Compare the actual discharge slope k with the preset discharge slope k1;
[0014] If k > k1, then the relay is determined not to be stuck.
[0015] If k≤k1, then the relay is determined to be stuck.
[0016] In one possible implementation, before the step of returning the actual discharge slope k of the bus capacitor of the motor controller, the method further includes:
[0017] The deviation between the actual discharge slope k and the desired discharge slope k2 is input to the closed-loop controller, which adjusts the frequency of the PWM signal according to the deviation.
[0018] In one possible implementation, after the closed-loop controller adjusts the frequency of the PWM signal according to the deviation, it further includes:
[0019] The system checks whether the discharge is completed within the first preset time. If not, a discharge failure fault is reported.
[0020] In one possible implementation, if not, reporting a discharge failure fault is replaced by:
[0021] If not, increment the value of the first discharge failure counter by one, and determine whether the value of the first discharge failure counter is greater than the first preset value;
[0022] If the value of the first discharge failure counter is not greater than the first preset value, return to the step of obtaining the actual discharge slope k of the bus capacitor of the motor controller;
[0023] If the value of the first discharge failure counter is greater than the first preset value, a discharge failure fault is reported.
[0024] In one possible implementation, if the statement "if so" reports a discharge failure fault, it is replaced with:
[0025] The frequency of the PWM signal is increased to a preset safety upper limit value, and it is detected whether the relay returns to normal within a second preset time. If yes, the step of inputting the deviation between the actual discharge slope k and the expected discharge slope k2 into the closed-loop controller is executed. If no, the value of the second discharge failure counter is incremented by one, and it is determined whether the value of the second discharge failure counter is greater than the second preset value.
[0026] If the value of the second discharge failure counter is not greater than the second preset value, return to the step of obtaining the actual discharge slope k of the bus capacitor of the motor controller;
[0027] If the value of the second discharge failure counter is greater than the second preset value, a discharge failure fault is reported.
[0028] In one possible implementation, at least two phase arms of the motor controller simultaneously perform preset actions, including: all three phase arms of the motor controller simultaneously perform preset actions.
[0029] Alternatively, the control of at least two phase bridge arms of the motor controller to simultaneously perform preset actions includes: grouping the A-phase and B-phase bridge arms of the motor controller into one group, the B-phase and C-phase bridge arms into one group, and the A-phase and C-phase bridge arms into one group, and controlling the three groups of bridge arms to take turns performing preset actions.
[0030] In one possible implementation, after at least two phase bridge arms of the motor controller simultaneously perform a preset action, the method further includes: detecting the actual drive voltage of the power switch controlled by the PWM signal; if the deviation between the actual drive voltage and the expected drive voltage exceeds a preset range, determining that the PWM signal is distorted.
[0031] In one possible implementation, the pulse width of the PWM signal is limited, causing the power switch controlled by the PWM signal to be in a partially on state during the high level of the PWM signal.
[0032] A second aspect of this application provides an active discharge control device for a motor controller, comprising: a bridge arm control unit;
[0033] The bridge arm control unit is used to control at least two phase bridge arms of the motor controller to simultaneously perform preset actions in response to an active discharge command.
[0034] The execution of the preset action includes: the power switch of the first half of the bridge arm is fully turned on; the power switch of the second half of the bridge arm is periodically switched between incompletely turned on and off under the control of the PWM signal.
[0035] A third aspect of this application provides a computer program product including computer-readable instructions that, when executed on the control circuit of a motor controller, cause the control circuit to implement the active discharge control method of the motor controller as described in the first aspect or any implementation thereof.
[0036] A fourth aspect of this application provides a motor controller, the control circuit of which includes at least one processor and a memory connected to the processor, wherein:
[0037] The memory is used to store computer programs;
[0038] The processor is used to execute the computer program so that the control circuit can implement the motor controller active discharge control method of the first aspect or any implementation thereof.
[0039] The fifth aspect of this application provides an electric drive system, including: a motor controller as described in the fourth aspect above.
[0040] The sixth aspect of this application provides a vehicle, including: an electric drive system as described in the fifth aspect above.
[0041] The seventh aspect of this application provides a computer storage medium carrying one or more computer programs, which, when executed by the control circuit of a motor controller, enable the control circuit to implement the active discharge control method of the motor controller described in the first aspect or any implementation thereof.
[0042] By means of the above technical solution, the motor controller active discharge control method provided in this application controls at least two phase bridge arms of the motor controller to periodically switch between incomplete conduction and off states after receiving an active discharge command, thereby using the switching loss and conduction loss of the power switching transistor to consume the energy of the bus capacitor without introducing additional hardware, thus saving cost and PCB area. Attached Figure Description
[0043] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.
[0044] Figure 1 A circuit schematic diagram of a motor controller provided in this application;
[0045] Figure 2 A flowchart of an active discharge control method for a motor controller is provided in this application;
[0046] Figure 3 Flowchart of another active discharge control method for a motor controller provided in this application;
[0047] Figure 4 Flowchart of another active discharge control method for a motor controller provided in this application;
[0048] Figure 5 This application provides a schematic diagram of the structure of an active discharge control device for a motor controller. Detailed Implementation
[0049] In order to ensure the accuracy of the citations and the fluency of reading, the key technical terms, abbreviations or acronyms used in the text are summarized and explained as follows:
[0050] IGBT: Insulated Gate Bipolar Transistor;
[0051] PCB: Printed Circuit Board;
[0052] PWM: Pulse Width Modulation;
[0053] ASC: Active Short Circuit;
[0054] MCU: Microcontroller Unit.
[0055] In the drive system of an electric vehicle, the motor controller is responsible for converting the DC power output from the battery pack into AC power required by the drive motor, and controlling the motor's speed and torque to ensure the vehicle can drive smoothly and efficiently. Its working principle is as follows: Figure 1 As shown, the motor controller transmits the DC power output from the battery pack to its internal components via the DC bus. After smoothing and energy storage by the internal bus capacitors, the power is then transmitted to the three-phase bridge arm. This three-phase bridge arm consists of three independent arms (referred to as phase A, phase B, and phase C), each comprising an upper and lower arm. Each arm contains at least one power switch (such as an IGBT) for power conversion and control. The motor controller's control system precisely controls the switching states of the power switches in the three-phase bridge arm to generate AC voltage and current matching the motor's operating requirements. This converts DC power into AC power needed to drive the motor and controls its speed and torque. This process ensures the electric vehicle can drive smoothly and efficiently, providing a comfortable and safe driving experience.
[0056] Figure 1In this diagram, the bus capacitors are marked with the symbol "C", and the motors are marked with the symbol "M". The power switch transistors of the upper arm of phase A are marked as Q1, the power switch transistors of the lower arm of phase A are marked as Q2, the power switch transistors of the upper arm of phase B are marked as Q3, the power switch transistors of the lower arm of phase B are marked as Q4, the power switch transistors of the upper arm of phase C are marked as Q5, and the power switch transistors of the lower arm of phase C are marked as Q6.
[0057] During continuous vehicle operation, the bus capacitor efficiently accumulates energy to cope with voltage fluctuations and instantaneous energy demands that the motor may encounter during operation. At critical moments, the bus capacitor can rapidly release energy, providing stable voltage support and rapid energy release for the motor, ensuring the continuity and stability of power output.
[0058] However, even after the power supply (i.e., the battery pack) is disconnected, the bus capacitor may still retain high-voltage charges due to its energy storage characteristics. These residual high-voltage charges constitute a potential hazard, especially in emergencies such as collisions or short circuits, where the high-voltage charges may be suddenly released, causing serious injury to those nearby. Furthermore, during routine vehicle maintenance, if workers do not take appropriate protective measures and accidentally touch the bus capacitor, an electric shock may occur.
[0059] To avoid such safety risks, the motor controller is designed with an active discharge function. When the power is cut off, the active discharge mechanism is immediately activated, switching to a dedicated discharge circuit to quickly and safely release any residual high-voltage charge in the bus capacitors to below a safe level. This active discharge mechanism ensures that even after the power is cut off, there is no high-voltage charge inside the bus capacitors that poses a threat to human health, thus protecting personnel safety during maintenance and emergency handling.
[0060] Existing active discharge mechanisms mainly achieve discharge through a discharge resistor. That is, when active discharge is required, a discharge resistor is connected in parallel with the bus capacitor to release the energy of the bus capacitor by converting it into heat energy. However, the addition of the discharge resistor increases the cost and PCB area.
[0061] To save costs and PCB area, this application provides an active discharge control method for a motor controller. This method primarily involves, upon receiving an active discharge command, controlling at least two phase bridge arms of the motor controller to periodically switch between incomplete on and off states simultaneously. This utilizes the switching and conduction losses of the power switching transistors to dissipate the energy of the bus capacitor, eliminating the need for additional hardware and saving costs and PCB area.
[0062] The active discharge control method for a motor controller provided in this application will be described in detail below with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in this application are also applicable to similar technical problems.
[0063] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.
[0064] This application provides an active discharge control method for a motor controller, which specifically includes: responding to an active discharge command, controlling at least two phase bridge arms of the motor controller to simultaneously perform preset actions.
[0065] Among them, at least two phase bridge arms of the motor controller simultaneously perform preset actions, that is: x (2≤x≤3) phase bridge arms of the motor controller simultaneously perform preset actions, while the remaining 3-x phase bridge arms remain in the default off state.
[0066] Each phase arm in the x-phase bridge arm performs the preset action, including: the power switch of the first half-arm of the phase arm is fully turned on, while the power switch of the second half-arm of the phase arm periodically switches between incomplete on and off states under the control of a PWM signal; the incomplete on means that the power switch is turned on with a resistance value exceeding a preset impedance during the high level of the PWM signal, but does not reach a fully on state; the pulse width of the PWM signal can be limited so that the power switch is in an incomplete on state during the high level of the PWM signal, and the preset impedance is an impedance threshold set to avoid shoot-through of the phase arm. Wherein, the first half-arm is the upper bridge arm and the second half-arm is the lower bridge arm, or the first half-arm is the lower bridge arm and the second half-arm is the upper bridge arm.
[0067] The working principle of the embodiments of this application will now be analyzed as follows:
[0068] A PWM signal is a technique that converts analog signal levels into digital signal levels. It simulates different voltage or current levels by controlling the pulse width of the PWM signal (the pulse width refers to the duration of the high-level signal within one PWM cycle). In power control applications, PWM signals are used to control the on / off state of power switches. Specifically, by adjusting the pulse width of the PWM signal, the driving voltage of the power switch can be changed, thereby altering the on / off state of the power switch.
[0069] The on / off states of power switching transistors are mainly divided into: fully on, partially on, and off.
[0070] The so-called fully on state means that the power switch is turned on with almost no impedance during the high level of the PWM signal, allowing current to flow freely through the power switch.
[0071] The so-called incomplete conduction state refers to the power switch being turned on with a certain impedance during the high level of the PWM signal. The power switch allows current to pass through, but the magnitude of the current is modulated by the pulse width of the PWM signal.
[0072] The so-called off state refers to the power switch being turned off during the low level of the PWM signal, blocking the flow of current.
[0073] For any phase arm, when both the upper and lower power switches of that phase arm are fully turned on, that phase arm enters a shoot-through state (conducting with almost no impedance), causing the bus capacitor to be short-circuited directly through that phase arm. When that phase arm is shoot-through, if the drive voltage of the power switches in both the upper and lower arms remains unchanged (i.e., the drive voltage applied to the power switches when the motor controller is working normally), the short-circuit current flowing through that phase arm will damage the power switches.
[0074] When a phase bridge arm is shoot-through, by significantly reducing the drive voltage of the power switches in the upper and lower bridge arms of that phase bridge arm, the short-circuit current flowing through that phase bridge arm can be limited below the limit value of the power switches, thereby preventing overcurrent damage to the power switches in the upper and lower bridge arms of that phase bridge arm. However, the existing power supply cannot meet the requirement of significantly reducing the drive voltage, and an additional suitable power supply is needed to meet this requirement, which will increase additional cost and PCB area.
[0075] This embodiment of the application avoids reducing the original driving voltage by limiting the pulse width of the PWM signal. Specifically, this embodiment keeps the power switches of the first half of the x-phase bridge arm (2≤x≤3) fully turned on, while reducing the pulse width of the PWM signal. This causes the power switches of the second half of the x-phase bridge arm (hereinafter referred to as the discharge bridge arm) to periodically switch between incomplete on and off states under the control of the PWM signal. At this time, it can be regarded as the entire discharge bridge arm periodically switching between incomplete on and off states, and there will be no bridge arm shoot-through state at any time, thus preventing overcurrent damage to the power switches on the discharge bridge arm. Meanwhile, the remaining 3-x phase bridge arms remain in the off state (that is, the upper and / or lower bridge arms of the remaining 3-x phase bridge arms remain in the off state).
[0076] Conduction loss is the power loss generated by a power switch in its fully on / partially on state. Switching loss is the energy loss caused by the switching action of a power switch. Switching losses mainly include two types: turn-on loss and turn-off loss. Turn-on loss refers to the power loss generated when the power switch changes from off to fully on / partially on. Turn-off loss refers to the power loss generated when the power switch changes from fully on / partially on to off. When the discharge bridge arm switches between the partially on and off states, and the non-discharge bridge arm remains off, the energy of the bus capacitor is mainly consumed by the switching and conduction losses generated by the power switch in the second half of the discharge bridge arm, without the need to introduce additional circuit components. Therefore, the cost is low and the PCB area is not increased.
[0077] With a fixed PWM signal pulse width and frequency, a larger x value results in a faster active discharge rate. Furthermore, the number of switching operations of the power switching transistors has a certain impact on their lifespan and reliability. Therefore, given a fixed PWM signal pulse width and frequency, compared to setting only one phase of the bridge arm to perform the preset action (i.e., periodic switching between incomplete on and off states), to minimize the number of switching operations of the power switching transistors in the second half-arm of a single bridge arm and to shorten the active discharge time, x=3 can be set.
[0078] When x=3, the motor controller is equivalent to activating ASC. ASC is a safety protection mechanism in the motor control system that achieves active short circuit of the motor by selectively turning on (fully conducting) or off the upper and lower bridge arms of the power switching transistors. In specific situations, such as vehicle loss of control, power battery failure, or abnormal motor speed, ASC can quickly intervene to ensure the safety of the vehicle and system by generating reverse torque or isolating the motor. ASC is divided into two types: upper ASC (i.e., upper bridge arm short circuit) and lower ASC (i.e., lower bridge arm short circuit). Upper ASC specifically means that when needed, the power switching transistor of the lower bridge arm is turned on (fully conducting) while the power switching transistor of the upper bridge arm is turned off, so that the motor windings form a closed loop, achieving active short circuit. Lower ASC is the opposite of upper ASC; it turns on (fully conducting) the power switching transistor of the upper bridge arm while turning off the power switching transistor of the lower bridge arm, also achieving active short circuit.
[0079] When the requirements for active discharge time are not strict, x=2 can also be set, and the A-phase and B-phase bridge arms can be grouped together, the B-phase and C-phase bridge arms can be grouped together, and the A-phase and C-phase bridge arms can be grouped together. The three groups of bridge arms can be controlled to take turns to perform the preset action. Compared with the scheme of setting only one phase bridge arm to perform the preset action or setting two fixed phase bridge arms to perform the preset action, the number of switching times of the power switch tube of the second half bridge arm on a single bridge arm can be reduced.
[0080] In summary, upon receiving an active discharge command, the embodiments of this application control the power switching transistors of the first half-bridge arm on at least two phases of the motor controller to be fully turned on, while the power switching transistors of the second half-bridge arm periodically switch between incompletely turned on (incompletely turned on can be achieved by limiting the pulse width of the PWM signal) and off state under the control of the PWM signal. This utilizes the switching and conduction losses of the power switching transistors to consume the energy of the bus capacitor and achieve active discharge without the need for additional hardware.
[0081] Based on any of the embodiments provided above, after at least two phase bridge arms of the motor controller simultaneously perform preset actions, the method further includes: obtaining the actual discharge slope k of the bus capacitor of the motor controller; determining whether the relay of the battery pack is stuck based on the actual discharge slope k; if stuck, reporting a discharge failure fault; if not stuck, returning to the step of obtaining the actual discharge slope k of the bus capacitor of the motor controller until the discharge is completed.
[0082] The working principle of the embodiments of this application will now be analyzed as follows:
[0083] The relays in the battery pack are installed on the charging and discharging circuit to control the on / off state of the circuit. During actual operation, relays inevitably experience sticking. Relay sticking mainly refers to the relay contacts (i.e., the switching part) becoming stuck due to various reasons, preventing them from disconnecting properly.
[0084] Active discharge occurs when the battery pack's relays are disconnected. If the relays are stuck during or after active discharge, the bus capacitor voltage will remain high, causing thermal damage to the power switching transistors in the discharge bridge arm. To address this, this embodiment periodically detects the actual drop slope of the bus capacitor voltage (i.e., the actual discharge slope k) after active discharge begins. Whether k matches expectations is used to determine if the battery pack's relays are stuck, allowing for timely intervention, such as issuing an alarm, to ensure the safe operation of the battery pack and the entire system.
[0085] Among them, the determination of whether the relay of the battery pack is stuck is based on the actual discharge slope k. For example, the actual discharge slope k is compared with the preset discharge slope k1; if k > k1, the relay is determined not to be stuck; if k ≤ k1, the relay is determined to be stuck.
[0086] Based on the previous embodiment, before returning to the step of obtaining the actual discharge slope k of the bus capacitor of the motor controller, the deviation between the actual discharge slope k and the desired discharge slope k2 can be input to the closed-loop controller. The closed-loop controller adjusts the frequency of the PWM signal of the discharge bridge arm according to the deviation. k2 is a preset value.
[0087] Furthermore, after the closed-loop controller adjusts the frequency of the PWM signal according to the deviation, it can also detect whether discharge is completed within the first preset time t1. If so, the discharge is successful; otherwise, a discharge failure fault is reported. A corresponding active discharge control method for a motor controller is as follows: Figure 2 As shown, it includes:
[0088] Step S01: In response to the active discharge command, control at least two phase bridge arms of the motor controller to simultaneously perform preset actions, and then proceed to step S02.
[0089] Step S02: Obtain the actual discharge slope k of the bus capacitor of the motor controller, and determine whether the relay of the battery pack is stuck based on the actual discharge slope k; if not, proceed to step S03; if yes, proceed to step S05.
[0090] Step S03: Input the deviation between the actual discharge slope k and the desired discharge slope k2 into the closed-loop controller. The closed-loop controller adjusts the frequency of the PWM signal of the discharge bridge arm according to the deviation, and then proceeds to step S04.
[0091] Step S04: Detect whether the discharge is completed within the first preset time t1. If yes, the discharge is successful and the current round of control ends; otherwise, proceed to step S05.
[0092] Step S05: Report a discharge failure fault and end the current round of control.
[0093] Now on Figure 2 The working principle of the illustrated embodiment is analyzed as follows:
[0094] When the relay is not stuck, adjusting the frequency of the PWM signal can change the total duration for which the power switch of the second half-arm on the discharge bridge arm is in a partially conducting state within a finite time. The higher the frequency of the PWM signal, the longer this total duration, and the larger the actual discharge slope k; conversely, the lower the frequency of the PWM signal, the shorter the total duration, and the smaller the actual discharge slope k. If the power switch operates at a high switching frequency for a long time, the accumulated thermal stress will cause thermal damage to the power switch. To avoid thermal damage caused by the power switch being in a rapid discharge state for an extended period, and to ensure discharge efficiency, this embodiment of the application, under the condition that the relay is not stuck, adjusts the frequency of the PWM signal through a closed-loop controller based on the deviation between the actual discharge slope k and the expected discharge slope k2 (that is, using the expected discharge slope k2 as the setpoint of the closed-loop controller, and the actual discharge slope k as the feedback value of the closed-loop controller, the closed-loop controller adjusts the control quantity, i.e., the frequency of the PWM signal, according to the deviation between the setpoint and the feedback value until the deviation is reduced to an acceptable range). This ensures that the actual discharge slope k always meets expectations and will not deviate significantly due to changes in the performance parameters of the power switch. Furthermore, this embodiment of the application also strictly controls the discharge duration under the condition that the relay is not stuck. If the bus capacitor voltage drops below the preset voltage within the first preset time t1, it is considered a successful discharge, i.e., a complete discharge. Conversely, if the discharge duration under this condition exceeds the first preset time t1 and the bus capacitor voltage is still higher than the preset voltage, it is considered a discharge failure, and a discharge failure fault is reported. The cause of the fault is that the power switch itself is abnormal.
[0095] If the relay sticks together, the bus capacitor voltage will remain high. Under these circumstances, the heat accumulated on the power switch of the discharge bridge arm during prolonged active discharge will cause thermal damage to the power switch. Therefore, when relay sticking is detected, a discharge failure fault is reported, and the cause of the fault is relay sticking.
[0096] In summary, upon receiving an active discharge command, this embodiment controls the power switch of the first half-bridge arm on at least one phase of the motor controller to be fully turned on. The power switch of the second half-bridge arm, under the control of a PWM signal, periodically switches between incompletely turned-on (achieved by limiting the pulse width of the PWM signal) and off states. This utilizes the switching and conduction losses of the power switches to dissipate the energy of the bus capacitor without introducing additional hardware. Furthermore, this embodiment also determines whether the relays in the battery pack are stuck based on the actual discharge slope k of the bus capacitor. If not stuck, the frequency of the PWM signal is adjusted in real time to complete the active discharge within the required time range without causing thermal damage to the power switches due to excessively rapid discharge. If stuck, a fault is reported, thus preventing thermal damage to the power switches.
[0097] Based on the previous embodiment, such as Figure 3 As shown in the embodiments of this application, another method for active discharge control of a motor controller is also disclosed, including:
[0098] Step S11: In response to the active discharge command, control at least two phase bridge arms of the motor controller to simultaneously perform preset actions, and then proceed to step S12.
[0099] Step S12: Obtain the actual discharge slope k of the bus capacitor of the motor controller, and determine whether the relay of the battery pack is stuck based on the actual discharge slope k; if not, proceed to step S13; if yes, proceed to step S16.
[0100] Step S13: Input the deviation between the actual discharge slope k and the desired discharge slope k2 into the closed-loop controller. The closed-loop controller adjusts the frequency of the PWM signal of the discharge bridge arm according to the deviation, and then proceeds to step S14.
[0101] Step S14: Detect whether the discharge is completed within the first preset time t1. If yes, the discharge is successful and the current round of control ends; otherwise, proceed to step S15.
[0102] Step S15: Increment the value n_1 of the first discharge failure counter by one, and determine whether the value n_1 of the first discharge failure counter is greater than the first preset value n1; if n_1≤n1, return to step S12; if n_1>n1, proceed to step S16.
[0103] Step S16: Report a discharge failure fault and end this round of control.
[0104] Compared to Figure 2 The embodiment shown, Figure 3 The illustrated embodiment adds step S15. The principle behind this addition is as follows:
[0105] During operation, power switching transistors inevitably experience abnormal performance parameters. These abnormalities may automatically recover to normal after a period of time. For example, a momentary fault in the power switch may cause abnormal performance parameters; however, if the fault is transient or minor, the power switch may automatically recover to normal after a period of time through its self-healing capabilities. Alternatively, power switches may have built-in self-protection mechanisms that automatically adjust their operating state to prevent further damage when internal abnormalities are detected, and automatically return to normal operation once the abnormality is resolved. Furthermore, external electromagnetic interference may affect the performance parameters of the power switch; when the interference source disappears or weakens, its performance parameters may automatically return to normal.
[0106] If the performance parameters of the power switch transistor malfunction and then automatically return to normal after a period of time, it will result in a discharge delay. Therefore, if the operating time of the relay under non-sticking conditions exceeds the expected time range (i.e., the first preset time t1), multiple discharge attempts can be made to ensure that the power switch transistor can quickly complete the discharge action whenever it is capable of normal discharge at any given time. If discharge fails after multiple attempts, it is assumed that the performance parameters of the power switch transistor cannot automatically return to normal within a short period, and a fault is reported.
[0107] Based on the previous embodiment, such as Figure 4 As shown in the embodiments of this application, another method for active discharge control of a motor controller is also disclosed, including:
[0108] Step S21: In response to the active discharge command, control at least two phase bridge arms of the motor controller to simultaneously perform preset actions, and then proceed to step S22.
[0109] The execution of the preset action includes: the power switch of the first half of the bridge arm is fully turned on, while the power switch of the second half of the bridge arm switches between incompletely turned on and off states under the control of the PWM signal; the incomplete turn-on means that the power switch is turned on with a resistance value exceeding the preset impedance during the high level of the PWM signal, but does not reach the state of full turn-on; the pulse width of the PWM signal is limited so that the power switch is in the incompletely turned-on state during the high level of the PWM signal.
[0110] Step S22: Obtain the actual discharge slope k of the bus capacitor of the motor controller, and determine whether the relay of the battery pack is stuck based on the actual discharge slope k; if not, proceed to step S23; if yes, proceed to step S26.
[0111] Step S23: Input the deviation between the actual discharge slope k and the desired discharge slope k2 into the closed-loop controller. The closed-loop controller adjusts the frequency of the PWM signal of the discharge bridge arm according to the deviation, and then proceeds to step S24.
[0112] Step S24: Detect whether the discharge is completed within the first preset time t1. If yes, the discharge is successful and the current round of control ends; otherwise, proceed to step S25.
[0113] Step S25: Increment the value n_1 of the first discharge failure counter by one, and determine whether the value n_1 of the first discharge failure counter is greater than the first preset value n1; if n_1≤n1, return to step S22; if n_1>n1, proceed to step S29.
[0114] Step S26: Increase the frequency of the PWM signal to a preset safety upper limit value, and then proceed to step S27.
[0115] Step S27: Detect whether the relay has returned to normal state within the second preset time t2. If yes, proceed to step S23; otherwise, proceed to step S28.
[0116] Step S28: Increment the value n_2 of the second discharge failure counter by one, and determine whether the value n_2 of the second discharge failure counter is greater than the second preset value n2; if n_2≤n2, return to step S22; if n_2>n2, proceed to step S29.
[0117] Step S29: Report a discharge failure fault and end this round of control.
[0118] Compared to Figure 3 The embodiment shown, Figure 4 The illustrated embodiment adds steps S26 to S28. The principle analysis is as follows:
[0119] After a relay becomes stuck, it may automatically return to normal after a period of time. For example, in some cases, the equipment or system containing the relay may be subjected to external vibration or impact. This vibration may help break the adhesion between the relay contacts, allowing the relay to automatically return to normal operation after a period of time.
[0120] If the relay automatically recovers after a period of time after sticking, the system switches to the discharge strategy for non-sticking conditions. If it is still sticking, the system can continue to try multiple times to ensure that the relay can be detected in time when it recovers. If it is still sticking after multiple attempts, the system assumes that the relay sticking cannot automatically recover in a short time and reports a fault.
[0121] To achieve rapid detection of whether a relay sticking has recovered, this embodiment increases the frequency of the PWM signal to a preset safety upper limit. If the relay recovers, the actual discharge slope k will rapidly increase to meet expectations; otherwise, the actual discharge slope k will remain essentially unchanged. The safety upper limit is set to ensure that the power switching transistor does not suffer thermal damage.
[0122] In any of the above-disclosed embodiments, during the transmission of the PWM signal from the motor controller's control system to the power switch, the PWM signal may be distorted due to factors such as line impedance and electromagnetic interference. This distortion may change the waveform, amplitude, or phase of the PWM signal, causing abnormalities in the drive voltage signal of the power switch, which in turn leads to unexpected discharge of the bus capacitor, resulting in power switch failure. Therefore, distortion verification of the PWM signal can be performed based on the drive voltage. The actual drive voltage of the power switch controlled by the PWM signal is detected. If the deviation between the actual drive voltage and the expected drive voltage exceeds a preset range, it is determined that the PWM signal has been distorted during transmission or control.
[0123] Furthermore, embodiments of this application also disclose an active discharge control device for a motor controller, such as... Figure 5 As shown, it includes a bridge arm control unit 100:
[0124] The bridge arm control unit 100 is used to control at least two phase bridge arms of the motor controller to simultaneously perform preset actions in response to an active discharge command.
[0125] The execution of the preset action includes: the power switch of the first half of the bridge arm is fully turned on; the power switch of the second half of the bridge arm is periodically switched between incompletely turned on and off under the control of the PWM signal.
[0126] In one possible implementation, see still Figure 5 The motor controller active discharge control device further includes:
[0127] The discharge slope acquisition unit 200 is used to acquire the actual discharge slope k of the bus capacitor of the motor controller after the bridge arm control unit 100 controls at least two phase bridge arms of the motor controller to perform preset actions simultaneously.
[0128] The relay adhesion judgment unit 300 is used to determine whether the relays of the battery pack are stuck based on the actual discharge slope k.
[0129] The first discharge strategy execution unit 400 is used to return to the discharge slope acquisition unit 200 when the relay adhesion judgment unit 300 determines that the result is no, until the discharge is completed.
[0130] The second discharge strategy execution unit 500 is used to report a discharge failure fault when the relay adhesion judgment unit 300 judges that the result is yes.
[0131] In one possible implementation, the first discharge strategy execution unit 400 is further configured to input the deviation between the actual discharge slope k and the desired discharge slope k2 into the closed-loop controller before returning to the discharge slope acquisition unit 200, wherein the closed-loop controller adjusts the frequency of the PWM signal according to the deviation.
[0132] In one possible implementation, the first discharge strategy execution unit 400 is further configured to detect whether discharge is completed within a first preset time after the closed-loop controller adjusts the frequency of the PWM signal according to the deviation, and if not, report a discharge failure fault.
[0133] In one possible implementation, the step of reporting a discharge failure fault if no is reported is replaced by: if no, incrementing the value of the first discharge failure counter by one, and determining whether the value of the first discharge failure counter is greater than a first preset value; if the value of the first discharge failure counter is not greater than the first preset value, returning to the discharge slope acquisition unit 200; if the value of the first discharge failure counter is greater than the first preset value, reporting a discharge failure fault.
[0134] In one possible implementation, instead of reporting a discharge failure fault when the relay adhesion judgment unit 300 determines the result as yes, the following steps are taken: when the relay adhesion judgment unit 300 determines the result as yes, the frequency of the PWM signal is increased to a preset safety upper limit value, and it is detected whether the relay returns to normal within a second preset time. If yes, the first discharge strategy execution unit 400 is triggered to start executing the step of inputting the deviation between the actual discharge slope k and the expected discharge slope k2 into the closed-loop controller. If no, the value of the second discharge failure counter is incremented by one, and it is determined whether the value of the second discharge failure counter is greater than a second preset value. If the value of the second discharge failure counter is not greater than the second preset value, the discharge slope acquisition unit 200 is triggered again. If the value of the second discharge failure counter is greater than the second preset value, a discharge failure fault is reported.
[0135] In one possible implementation, the bridge arm control unit 100 controls at least two phases of the motor controller to simultaneously perform a preset action, specifically configured to control three phases of the motor controller to simultaneously perform a preset action.
[0136] Alternatively, the bridge arm control unit 100 controls at least two phases of the motor controller to simultaneously perform preset actions. Specifically, the A-phase and B-phase bridge arms of the motor controller are grouped together, the B-phase and C-phase bridge arms are grouped together, and the A-phase and C-phase bridge arms are grouped together, and the three groups of bridge arms are controlled to take turns performing preset actions.
[0137] In one possible implementation, the motor controller active discharge control device further includes: a signal distortion judgment unit, used to detect the actual drive voltage of the power switch controlled by the PWM signal, and if the deviation between the actual drive voltage and the expected drive voltage exceeds a preset range, the PWM signal is determined to be distorted.
[0138] Furthermore, this application also discloses a computer program product, including computer-readable instructions, which, when executed on the control circuit of a motor controller, cause the control circuit to implement any of the above-described motor controller active discharge control methods.
[0139] Furthermore, this application also discloses a motor controller, including a main circuit and a control circuit; the main circuit is the core part of the motor controller, responsible for the transmission and conversion of electrical energy; the control circuit, as the "brain" of the motor controller, is responsible for receiving signals from sensors or external devices, and generating control commands based on these signals and preset control strategies. These control commands are then sent to the main circuit to achieve precise adjustment of the motor's operating state; the control circuit includes at least one processor and a memory connected to the processor, wherein:
[0140] The memory is used to store computer programs;
[0141] The processor is used to execute the computer program so that the control circuit can implement any of the above-described motor controller active discharge control methods.
[0142] In addition, embodiments of this application also disclose an electric drive system, including: any of the motor controllers described above.
[0143] In addition, embodiments of this application also disclose a vehicle, including any of the electric drive systems described above.
[0144] Furthermore, this application also discloses a computer storage medium carrying one or more computer programs. When the one or more computer programs are executed by the control circuit of the motor controller, the control circuit can implement any of the above-described motor controller active discharge control methods.
[0145] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the embodiments of this application. Therefore, the embodiments of this application are not to be limited to the embodiments shown herein, but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for active discharge control of a motor controller, characterized in that, include: In response to an active discharge command, at least two phase bridge arms of the motor controller simultaneously perform preset actions; The execution of the preset action includes: the power switch of the first half of the bridge arm is fully turned on; the power switch of the second half of the bridge arm is periodically switched between incompletely turned on and off under the control of the PWM signal.
2. The active discharge control method for a motor controller according to claim 1, characterized in that, After at least two phase bridge arms of the motor controller simultaneously perform preset actions, the system further includes: Obtain the actual discharge slope k of the bus capacitor of the motor controller; Determine whether the relays of the battery pack are stuck based on the actual discharge slope k; if so, report a discharge failure fault; if not, return to the step of obtaining the actual discharge slope k of the motor controller's bus capacitor until the discharge is completed.
3. The active discharge control method for a motor controller according to claim 2, characterized in that, The method of determining whether the relay of the battery pack is stuck based on the actual discharge slope k includes: Compare the actual discharge slope k with the preset discharge slope k1; If k > k1, then the relay is determined not to be stuck. If k≤k1, then the relay is determined to be stuck.
4. The active discharge control method for a motor controller according to claim 2 or 3, characterized in that, Before the step of returning the actual discharge slope k of the bus capacitor of the motor controller, the method further includes: The deviation between the actual discharge slope k and the desired discharge slope k2 is input to the closed-loop controller, which adjusts the frequency of the PWM signal according to the deviation.
5. The active discharge control method for a motor controller according to claim 4, characterized in that, After the closed-loop controller adjusts the frequency of the PWM signal according to the deviation, it further includes: The system checks whether the discharge is completed within the first preset time. If not, a discharge failure fault is reported.
6. The active discharge control method for a motor controller according to claim 5, characterized in that, If not, report a discharge failure fault and replace it with: If not, increment the value of the first discharge failure counter by one, and determine whether the value of the first discharge failure counter is greater than the first preset value; If the value of the first discharge failure counter is not greater than the first preset value, return to the step of obtaining the actual discharge slope k of the bus capacitor of the motor controller; If the value of the first discharge failure counter is greater than the first preset value, a discharge failure fault is reported.
7. The active discharge control method for a motor controller according to claim 6, characterized in that, If the above is true, and a discharge failure fault is reported, replace it with: The frequency of the PWM signal is increased to a preset safety upper limit value, and it is detected whether the relay returns to normal within a second preset time. If yes, the step of inputting the deviation between the actual discharge slope k and the expected discharge slope k2 into the closed-loop controller is executed. If no, the value of the second discharge failure counter is incremented by one, and it is determined whether the value of the second discharge failure counter is greater than the second preset value. If the value of the second discharge failure counter is not greater than the second preset value, return to the step of obtaining the actual discharge slope k of the bus capacitor of the motor controller; If the value of the second discharge failure counter is greater than the second preset value, a discharge failure fault is reported.
8. The active discharge control method for a motor controller according to claim 1, characterized in that, The control of at least two phase bridge arms of the motor controller to perform preset actions simultaneously includes: the control of three phase bridge arms of the motor controller to perform preset actions simultaneously. Alternatively, the control of at least two phase bridge arms of the motor controller to simultaneously perform preset actions includes: grouping the A-phase and B-phase bridge arms of the motor controller into one group, the B-phase and C-phase bridge arms into one group, and the A-phase and C-phase bridge arms into one group, and controlling the three groups of bridge arms to take turns performing preset actions.
9. The active discharge control method for a motor controller according to claim 1, characterized in that, After at least two phase bridge arms of the motor controller simultaneously perform preset actions, the method further includes: detecting the actual drive voltage of the power switch controlled by the PWM signal; if the deviation between the actual drive voltage and the expected drive voltage exceeds a preset range, the PWM signal is determined to be distorted.
10. The active discharge control method for a motor controller according to claim 1, characterized in that, The pulse width of the PWM signal is limited, causing the power switch controlled by the PWM signal to be in a partially on state during the high level of the PWM signal.
11. An active discharge control device for a motor controller, characterized in that, include: Bridge arm control unit; The bridge arm control unit is used to control at least two phase bridge arms of the motor controller to simultaneously perform preset actions in response to an active discharge command. The execution of the preset action includes: the power switch of the first half of the bridge arm is fully turned on; the power switch of the second half of the bridge arm is periodically switched between incompletely turned on and off under the control of the PWM signal.
12. A computer program product, characterized in that, It includes computer-readable instructions that, when executed on the control circuit of the motor controller, cause the control circuit to implement the active discharge control method of the motor controller as described in any one of claims 1 to 10.
13. A motor controller, characterized in that, Its control circuitry includes at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is used to execute the computer program so that the control circuit can implement the active discharge control method of the motor controller as described in any one of claims 1 to 10.
14. An electric drive system, characterized in that, include: The motor controller as described in claim 13.
15. A vehicle, characterized in that, include: The electric drive system as described in claim 14.
16. A computer storage medium, characterized in that, The computer storage medium carries one or more computer programs, which, when executed by the control circuit of the motor controller, enable the control circuit to implement the active discharge control method of the motor controller as described in any one of claims 1 to 10.