Active discharge method, device, storage medium and motor electronic control system

Abstract

The application discloses an active discharge method and device, a storage medium and an electric motor control system. When the electric motor control system receives an active discharge instruction, the active discharge method controls a direct-current converter to operate at a preset duty ratio and increases a current ripple to a preset current value; and maintains a switch loss value of the direct-current converter at a target loss value corresponding to the preset current value, so that the voltage of a bus capacitor is actively released. In the application, the direct-current converter is controlled to operate at the preset duty ratio, the switch loss value of the direct-current converter is maintained 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 electric motor control system is quickly released without adding an additional discharge circuit.

Description

Technical Field

[0001] This invention relates to the field of discharge technology, and in particular to an active discharge method, apparatus, storage medium, and motor control system. Background Technology

[0002] As the new energy vehicle market continues to expand, high power density, low cost, and long driving range are the major trends in automotive development. To improve motor efficiency and driving capability, and to fully utilize battery voltage, a DC-DC converter is added between the power battery and the motor drive inverter in the motor control system. When the battery voltage is low, the DC-DC converter can stably control the output voltage, keeping the system in optimal operating condition, and the motor can effectively utilize the bus voltage, always operating at its maximum capacity.

[0003] For safety reasons, when a new energy vehicle is powered off or involved in a collision, the energy stored in the motor and electronic control system needs to be released rapidly, i.e., active discharge. This generally requires reducing the voltage to below the safe voltage within a very short time. Existing discharge methods mainly rely on adding additional components to form a discharge circuit, which increases the cost of the motor and electronic control system to some extent.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this invention is to provide an active discharge method, device, storage medium, and motor control system, aiming to solve the technical problem of increased cost of motor control system during rapid discharge of stored energy in the prior art.

[0006] To achieve the above objectives, the present invention provides an active discharge method, which is applied to a motor control system including a DC-DC converter;

[0007] The active discharge method includes:

[0008] When the motor control system receives an active discharge command, it controls the DC converter to operate at a preset duty cycle and increases the current ripple to a preset current value.

[0009] Maintaining the switching loss value of the DC-DC converter at the target loss value corresponding to the preset current value allows the voltage of the bus capacitor to be actively released.

[0010] Optionally, before the step of controlling the DC-DC converter to operate at a preset duty cycle and increasing the current ripple to a preset current value when the motor control system receives an active discharge command, the method further includes:

[0011] Obtain the operating parameters of the motor control system;

[0012] Based on the operating parameters, a first mapping relationship between the output duty cycle of the DC-DC converter and the switching loss value is determined;

[0013] The preset duty cycle of the DC-DC converter is determined based on the first mapping relationship.

[0014] Optionally, the step of determining the preset duty cycle of the DC-DC converter based on the first mapping relationship includes:

[0015] The output duty cycle of the DC-DC converter corresponding to the maximum switching loss value is determined based on the first mapping relationship.

[0016] The output duty cycle corresponding to the maximum switching loss value is used as the preset duty cycle.

[0017] Optionally, the step of maintaining the switching loss value of the DC-DC converter at a target loss value corresponding to a preset current value, thereby actively releasing the voltage of the bus capacitor, includes:

[0018] Adjust the switching frequency of the switching transistors in the DC-DC converter to the target switching frequency;

[0019] Drive the switching transistors in the DC-DC converter according to the target switching frequency to maintain the switching loss value of the DC-DC converter at the target loss value and actively release the voltage of the bus capacitor.

[0020] Optionally, before the step of adjusting the switching frequency of the switching transistors in the DC-DC converter to the target switching frequency, the method further includes:

[0021] Obtain the second mapping relationship between the switching frequency and the switching loss value;

[0022] The target switching frequency corresponding to the target loss value is determined based on the second mapping relationship between the switching frequency and the switching loss value.

[0023] Optionally, the step of obtaining the second mapping relationship between the switching frequency and the switching loss value includes:

[0024] Obtain a third mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter;

[0025] Obtain a fourth mapping relationship between the switching frequency and the discharge rate of the switching transistor in the DC-DC converter;

[0026] A second mapping relationship between the switching frequency and the switching loss value is determined based on the third mapping relationship and the fourth mapping relationship.

[0027] Optionally, the step of maintaining the switching loss value of the DC-DC converter at a target loss value corresponding to a preset current value, thereby actively releasing the voltage of the bus capacitor, further includes:

[0028] When the motor control system includes a preset discharge circuit, the switching loss value of the DC-DC converter is maintained at the target loss value, and the preset discharge circuit is simultaneously controlled to actively release the voltage of the bus capacitor.

[0029] Furthermore, to achieve the above objectives, the present invention also provides an active discharge device, the active discharge device comprising:

[0030] The control module is used to control 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 an active discharge command.

[0031] The discharge module is used to maintain the switching loss value of the DC-DC converter at a target loss value corresponding to a preset current value, thereby actively releasing the voltage of the bus capacitor.

[0032] In addition, to achieve the above objectives, the present invention also provides a storage medium storing an active discharge program, which, when executed by a processor, implements the steps of the active discharge method.

[0033] Furthermore, to achieve the above objectives, the present invention also provides a motor control system, which includes: a DC-DC converter, an inverter, a motor, and an electronic control unit; the electronic control unit is connected to the control terminal of the switching transistor in the DC-DC converter, the DC-DC converter is connected to the power supply of the motor control system, the energy storage element, and the inverter, and the inverter is connected to the motor; the electronic control unit executes the steps of the active discharge method when it is running.

[0034] This invention provides an active discharge method, apparatus, storage medium, and motor control system. When the motor control system receives an active discharge command, the active discharge method controls a DC-DC converter to operate at a preset duty cycle and increases the current ripple to a preset current value; it maintains the switching loss value of the DC-DC converter at a target loss value corresponding to the preset current value, thereby actively releasing the voltage of the bus capacitor. In this invention, by controlling the DC-DC converter to operate at a preset duty cycle and maintaining the switching loss value of the DC-DC converter at the target loss value corresponding to the preset current value to actively release the voltage of the bus capacitor, the energy stored in the motor control system can be quickly released without adding an additional discharge circuit. Attached Figure Description

[0035] Figure 1This is a schematic diagram of the structure of the motor control system in the hardware operating environment involved in the embodiments of the present invention;

[0036] Figure 2 This is a flowchart illustrating the first embodiment of the active discharge method of the present invention;

[0037] Figure 3 This is a flowchart illustrating the second embodiment of the active discharge method of the present invention;

[0038] Figure 4 This is a schematic diagram of the first process of the third embodiment of the active discharge method of the present invention;

[0039] Figure 5 This is a schematic diagram of the second process of the third embodiment of the active discharge method of the present invention;

[0040] Figure 6 This is a flowchart illustrating the fourth embodiment of the active discharge method of the present invention;

[0041] Figure 7 This is a structural block diagram of the first embodiment of the active discharge device of the present invention.

[0042] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0043] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0044] Reference Figure 1 , Figure 1 This is a schematic diagram of the motor and electronic control system structure of the hardware operating environment involved in the embodiments of the present invention.

[0045] like Figure 1 As shown, the motor control system may include: a DC-DC converter, an inverter, a motor (MG), an energy storage element, and an electronic control unit (ECU). The ECU is connected to the control terminal of the switching transistor within the DC-DC converter. The DC-DC converter is connected to the power supply of the motor control system, the energy storage element, and the inverter. The inverter is connected to the motor. The electronic control element... Figure 1 It is not shown in the text.

[0046] Those skilled in the art will understand that Figure 1 The structure shown does not constitute a limitation on the motor control system and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0047] exist Figure 1 When the central control unit is running, it executes the steps that enable the active discharge method.

[0048] Based on the above hardware structure, an embodiment of the active discharge method of the present invention is proposed.

[0049] Reference Figure 2 , Figure 2 This is a flowchart illustrating the first embodiment of the active discharge method of the present invention, which presents the first embodiment of the active discharge method of the present invention.

[0050] In the first embodiment, the active discharge method includes the following steps:

[0051] Step S10: When the motor control system receives the active discharge command, it controls the DC converter to operate at a preset duty cycle and increases the current ripple to a preset current value.

[0052] It should be understood that the execution entity in this embodiment can be an electronic control unit (ECU) that controls the DC-DC converter within the motor control system. This ECU can be a device composed of control elements such as chips, microcontrollers, and ARM processors. Furthermore, the ECU can also be a hardware device such as a computer or laptop computer.

[0053] It should be understood that during normal operation, electric vehicles require the motor control system to supply power to the vehicle's motor so that it can function properly and provide sufficient power to the vehicle. When the vehicle is powered off or a collision occurs, the connection between the motor and the vehicle's battery needs to be disconnected. At this time, there will be some stored energy in the energy storage components within the motor control system, which needs to be released as quickly as possible to avoid potential safety hazards.

[0054] Reference Figure 1 It should be noted that a DC-DC converter can consist of an inductor and a certain number of switching transistors. Figure 1The DC-DC converter is generated by combining an inductor and two switching transistors. It is a power electronic device that converts DC power into controllable DC power, either voltage or current, required by a load. It breaks a constant DC voltage into a series of pulse voltages by rapidly switching the internal switching transistors on and off. The pulse width of this pulse series is changed by controlling the duty cycle, thereby regulating the average output voltage. The regulated average voltage is then filtered to obtain controllable DC power, either current or voltage, to the controlled load. The output duty cycle is the effective duty cycle output by the control unit for controlling the DC-DC converter. Within the effective duty cycle range, the DC-DC converter operates normally according to the signal output by the control unit; within the ineffective duty cycle range, the DC-DC converter remains off. The preset duty cycle refers to the pre-set duty cycle used to control the internal switching transistors of the DC-DC converter to conduct or cut off normally within one pulse cycle. The preset duty cycle can be within a threshold range of the output duty cycle, or it can be a specific value. For example, when the preset duty cycle is 50%, when the electronic control unit outputs a control signal, the DC converter is in normal working condition throughout the entire cycle of the output cycle of the control signal. However, during the DC change period, the first and second switching transistors are both in the conducting state for half a cycle, and the first and second switching transistors do not conduct at the same time.

[0055] In practical implementation, when the vehicle is powered off or a collision occurs, the electronic control unit (ECU) can output a control signal with a constant duty cycle to the DC-DC converter, thereby adjusting the output duty cycle of the DC-DC converter. When implemented in this way, the duty cycle of this control signal should be the same as the preset duty cycle. Alternatively, the ECU can output a control signal with a higher duty cycle, and then use other methods to control the on / off state of the switching transistors within the DC-DC converter to adjust the output duty cycle of the DC-DC converter to the preset duty cycle.

[0056] It should be understood that, referring to Figure 1 When both the contactor and the motor are disconnected, only a certain amount of energy is released through the energy storage elements, namely the two capacitors, through the inductor inside the DC-DC converter. At this time, the average current value through the inductor inside the DC-DC converter within the motor control system is close to 0. Switching losses include turn-on losses and turn-off losses. In fact, they refer to the losses generated when the first switch Q1 and the second switch Q2 switch states are switching at the positive and negative peak currents. The larger the peak current, the higher the loss. The conduction loss is also positively correlated with the magnitude of the instantaneous current; the larger the instantaneous current, the higher the loss.

[0057] It should be noted that current ripple refers to the current value fluctuating around the average current value. Due to the complementary on / off state changes of the two switching transistors, a certain current ripple is generated across the inductor. This current ripple is mainly formed by capacitor discharge, and its specific value fluctuates around the zero current value. (Refer to...) Figure 1 One charge-discharge cycle of a capacitor includes four processes: The first process is when the first switch Q1 is closed and the second switch Q2 is open, and the current flows from left to right through the body diode inside the first switch Q1. At this time, the first capacitor C1 discharges and the second capacitor C2 charges, and the instantaneous current value decreases from the peak value to 0. The second process is when the first switch Q1 is closed and the second switch Q2 is open, and the current flows from right to left through the first switch Q1. The first capacitor C1 charges and the second capacitor C2 discharges, and the instantaneous current value increases from 0 to the peak value. The third process is when the first switch Q1 is open and the second switch Q2 is closed, and the current flows from right to left through the body diode of the second switch Q2. The first capacitor C1 charges and the second capacitor C2 does not charge or discharge, and the instantaneous current value decreases from the peak value to 0. The fourth process is when the first switch Q1 is open and the second switch Q2 is closed, and the current flows from left to right through the second switch Q2. The first capacitor C1 discharges and the second capacitor C2 does not charge or discharge, and the instantaneous current value increases from 0 to the peak value.

[0058] In practical implementation, the electronic control device can continuously control the on and off states of the switching transistors in the DC-DC converter at a certain period to control the discharge of the energy storage element. Thus, the on and off states of the switching transistors in the DC-DC converter within the motor control system can generate current ripple within the motor control system.

[0059] Step S20: Maintain the switching loss value of the DC converter at the target loss value corresponding to the preset current value, thereby actively releasing the voltage of the bus capacitor.

[0060] It should be understood that, since the power supply to the motor control system and the motor are simultaneously disconnected, the current through the DC-DC converter is close to zero. The energy stored in the energy storage element will not generate excessive current, thus preventing excessive heat and potential safety incidents. Therefore, in this embodiment, the energy stored in the energy storage element can be actively released directly by utilizing the heat generated by the turn-on loss, turn-off loss, and continuous conduction loss of the switching transistor in the DC-DC converter during its on / off and continuous conduction states.

[0061] The first embodiment provides an active discharge method. When the vehicle is powered off or a collision occurs, this method adjusts the output duty cycle of the DC-DC converter to a preset duty cycle; controls the DC-DC converter to operate at the preset duty cycle, causing the stored electrical energy in the motor control system to form a current ripple; and actively releases the current ripple through the DC-DC converter. In this embodiment, by controlling the DC-DC converter to operate at a preset duty cycle and maintaining the switching loss value of the DC-DC converter at a target loss value corresponding to the preset current value, the voltage of the bus capacitor is actively released, achieving rapid release of energy stored in the motor control system without adding an additional discharge circuit.

[0062] Reference Figure 3 , Figure 3 This is a flowchart illustrating the second embodiment of the active discharge method of the present invention, based on the above. Figure 2 The first embodiment shown presents a second embodiment of the active discharge method of the present invention.

[0063] In the second embodiment, before step S10, the method further includes:

[0064] Step S101: Obtain the operating parameters of the motor control system.

[0065] It should be understood that when releasing parameters within the motor control system, the discharge rate can be increased by increasing the current value of the current ripple. The larger the current value of the current ripple, the faster the energy is released by the energy storage elements within the motor control system.

[0066] It should be noted that operating parameters refer to the parameters of each component within the motor control system under normal power supply or discharge conditions. Motor control parameters may include: bus voltage, switching frequency of the switching transistors, inductance reactance, inverter efficiency, etc. The specific operating parameters required are closely related to the components within the motor control system; different components require different operating parameters. Figure 1 For example, in Figure 1 In this context, operating parameters can include the bus voltage under normal operating conditions of the motor control system, the power supply voltage provided by the battery, the inductive reactance of the inductor, and the switching frequency of the switching transistor.

[0067] In practical implementation, the electronic control unit (ECU) can collect parameters such as voltage and current through sensors connected to the motor's electronic control system. It can also collect the voltage across the inductor and the current flowing through it, and calculate the inductive reactance based on the collected voltage and current values. Since the switching state of the switching transistor is directly related to the control signal output by the ECU, the switching frequency of the switching transistor can be directly determined based on the control signal output by the ECU.

[0068] Step S102: Determine the first mapping relationship between the output duty cycle and the switching loss value of the DC converter based on the operating parameters.

[0069] It should be understood that there is a certain mapping relationship between the output duty cycle of a DC-DC converter and the current value of the switching loss. Different output duty cycles of the DC-DC converter result in different current values ​​of the current ripple generated in the motor control system, thus leading to different switching loss values. The mapping relationship between the output duty cycle of the DC-DC converter and the current ripple generated in the motor control system can be determined based on the specific operating state of the motor control system. Figure 1 Taking the operating state of the motor control system as an example, the specific current value of the current ripple is ΔI = (U dc -U bat )*D / (L*f)=U dc *D*(1-D) / (L*f), where U dc U is the voltage of the bus in the motor control system. bat The power supply voltage provided by the battery for the motor control system, D is the output duty cycle of the DC-DC converter, f is the switching frequency, and L is the inductance value. Figure 1 The above formula represents the mapping relationship between the output duty cycle of the DC-DC converter and the current ripple generated in the motor control system. Then, based on the relationship between the current ripple and the switching loss value, the first mapping relationship between the output duty cycle and the switching loss value can be determined.

[0070] Step S103: Determine the preset duty cycle of the DC-DC converter according to the first mapping relationship.

[0071] 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 control system, the preset duty cycle of the DC converter can be directly determined based on the first mapping relationship and the required current ripple. At this time, the preset duty cycle corresponds to the required switching loss value.

[0072] Step S103 specifically also includes:

[0073] Step S1031: Determine the output duty cycle of the DC-DC converter corresponding to the maximum switching loss value based on the first mapping relationship.

[0074] It should be noted that the larger the current value of the current ripple, the greater the corresponding switching loss, the faster the discharge rate of the energy storage element, and the higher the efficiency. Therefore, when releasing the energy stored in the energy storage element of the motor control system, the switching loss can be adjusted by regulating the current ripple generated in the motor control system through adjusting the output duty cycle of the DC-DC converter.

[0075] It should be understood that, to ensure the discharge efficiency of the motor control system, the maximum value of the current ripple within the system can be determined based on this mapping relationship. According to the formula above, the maximum value of the current ripple is related to the bus voltage, the DC-DC converter's output duty cycle, the switching frequency within the DC-DC converter, and the inductive reactance. In a stable operating system, the maximum value is a fixed value for the bus voltage, the DC-DC converter's switching frequency, and the inductive reactance, while the DC-DC converter's output duty cycle can be directly controlled by the control unit. According to the formula corresponding to the mapping relationship, the DC-DC converter's output duty cycle and the current ripple exhibit a quadratic transformation relationship. When adjusting the current ripple, the DC-DC converter's output duty cycle can be directly determined based on the desired current ripple; this output duty cycle is then the output duty cycle corresponding to the maximum switching loss value.

[0076] Step S1032: Use the output duty cycle corresponding to the maximum switching loss value as the preset duty cycle.

[0077] It should be understood that when it is necessary to release the energy stored in the motor control system at the fastest rate, the corresponding preset duty cycle can be obtained directly according to the first mapping relationship. Then, the control unit adjusts the output duty cycle of the DC converter to the preset duty cycle and realizes the energy release process in the first embodiment, which will not be described in detail here.

[0078] The second embodiment provides an active discharge method. This method acquires the operating parameters of the motor control system and determines the relationship between the output duty cycle and switching loss of the DC-DC converter based on these parameters. The output duty cycle of the DC-DC converter is then adjusted to a preset duty cycle. The DC-DC converter is controlled to operate at the preset duty cycle, causing the stored energy in the motor control system to form a current ripple. The current ripple is actively released through the DC-DC converter. In this invention, the preset duty cycle is determined through a first mapping relationship, and the DC-DC converter is controlled to operate at the preset duty cycle. By actively releasing the current ripple through the DC-DC converter, the energy stored in the motor control system can be rapidly released without adding an additional discharge circuit.

[0079] Reference Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the first process of the third embodiment of the active discharge method of the present invention, based on the above. Figure 2 The first embodiment shown and Figure 3 The second embodiment shown presents a third embodiment of the active discharge method of the present invention.

[0080] In the third embodiment, step S20 may include:

[0081] Step S21: Adjust the switching frequency of the switching transistor in the DC-DC converter to the target switching frequency.

[0082] It should be understood that the operating time of the switching transistors within a DC-DC converter is closely related to the energy released; the longer the switching transistors are on within a cycle, the more energy is released in that cycle. Therefore, during the energy release process of the motor control system, the discharge rate of the motor control system can be increased by adjusting the switching frequency of the switching transistors within a complete discharge cycle.

[0083] In practical implementation, the electronic control unit (ECU) can adjust the switching frequency of the switching transistors within the DC-DC converter by controlling the frequency of the control signals output to them, thereby ensuring that the switching frequency is at the target frequency. Of course, other methods can also be used for adjustment, which are not specifically limited here.

[0084] Step S22: Drive the switching transistors in the DC-DC converter to maintain the switching loss value of the DC-DC converter at the target loss value and actively release the voltage of the bus capacitor according to the target switching frequency.

[0085] It should be understood that by increasing the switching frequency of the switching transistors in the DC-DC converter, the energy release rate stored in the motor control system can be further increased. Therefore, actively releasing the current ripple at the target switching frequency after adjustment can improve the energy release rate.

[0086] Reference Figure 5 In the third embodiment, step S21 may include the following:

[0087] Step S201: Obtain the second mapping relationship between the switching frequency and the switching loss value;

[0088] It should be understood that, according to the first mapping relationship, the switching frequency can increase the number of times the switching transistor is turned on within a fixed time, thereby increasing switching losses and improving the energy release rate within the motor control system. However, this will cause changes in the current value of the current ripple, resulting in a decrease in the energy release rate within the motor control system. Therefore, when adjusting the switching frequency of the switching transistor, a suitable target value should be selected between the switching frequency and the current value of the current ripple to ensure that the energy stored within the motor control system is released at the fastest possible rate.

[0089] It should be noted that the target switching frequency refers to the switching frequency at which the energy stored in the motor control system can be released at the fastest rate. In the specific acquisition process, the target switching frequency can be determined through extensive calculations by analyzing the influence of switching frequency on energy release, the influence of switching frequency on current ripple, and the influence between current ripple and energy release. Furthermore, considering the possibility of errors and computational randomness, the target switching frequency can be determined using a model trained on a large number of samples.

[0090] Step S202: Determine the target switching frequency corresponding to the target loss value based on the second mapping relationship between the switching frequency and the switching loss value;

[0091] It should be understood that, according to the formula relationship in the first embodiment above, there is a certain mapping relationship between the switching frequency and the current ripple. In this embodiment, the mapping relationship between the switching frequency and the current ripple is taken as the second mapping relationship.

[0092] It should be noted that, given a determined target switching frequency, the target current ripple corresponding to the target switching frequency can be determined based on the second mapping relationship between the switching frequency and the current ripple. Then, the current ripple is adjusted to the target current ripple by regulating the output duty cycle of the DC-DC converter. The target current ripple is the adjusted current ripple.

[0093] In practice, the target current ripple can be determined first, and then the target switching frequency can be determined based on the target current ripple and the second mapping relationship between the switching frequency and the current ripple. Finally, the switching frequency of the switching transistor can be adjusted according to the control signal output by the electronic control unit. Of course, the current ripple also needs to be adjusted to the target current ripple.

[0094] The switching transistors within the DC-DC converter are driven to actively release the voltage of the bus capacitor according to the target switching frequency.

[0095] It should be understood that when the target current ripple and the target switching frequency are both determined, the electronic control unit can directly control the switching transistors in the DC-DC converter to operate according to the output duty cycle corresponding to the target current ripple and the target switching frequency based on the output control signal, so as to safely release the energy stored in the motor electronic control system at the fastest speed.

[0096] The step S21 may be preceded by:

[0097] Step S2011: Obtain the third mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter;

[0098] It should be noted that there is a certain mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter. The larger the current ripple, the larger the current through the switching transistor, and the larger the switching loss value. In this case, the discharge rate of the switching transistor is faster. In this embodiment, the mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter is referred to as the third mapping relationship. The third mapping relationship is related to the specific operating parameters of the switching transistor. This third mapping relationship can also be expressed as the mapping relationship between current ripple and discharge rate.

[0099] In practical implementation, the electronic control unit can obtain a third mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter by testing the current flowing through the switching transistor in the electrode electronic control system and the corresponding discharge rate of the switching transistor. Of course, in this embodiment, the same switching transistor can also be used to perform external testing, and the test results can be input to the controllable device to obtain the third mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter.

[0100] Step S2012: Obtain the fourth mapping relationship between the switching frequency and the discharge rate of the switching transistor in the DC-DC converter;

[0101] It should be noted that the switching frequency directly affects the discharge time of the switching transistor. Within a fixed time period, the higher the switching frequency of the transistor, the more energy it releases within that time period, and the greater the corresponding discharge rate. In this embodiment, the mapping relationship between the switching frequency of the transistor and the discharge rate of the transistor within the DC-DC converter is used as the fourth mapping relationship.

[0102] Step S2013: Determine the target switching frequency of the switching transistors in the DC-DC converter based on the third mapping relationship and the fourth mapping relationship.

[0103] It should be understood that, given the third mapping relationship between ripple current and discharge rate of the switching transistor, and similarly the fourth mapping relationship between switching frequency and discharge rate of the switching transistor, the switching frequency and current ripple can be continuously adjusted based on the third and fourth mapping relationships until the target switching frequency or target current ripple corresponding to the maximum discharge rate is obtained.

[0104] In the third embodiment, the corresponding current ripple is obtained by adjusting the output duty cycle of the DC-DC converter, and then the switching frequency of the switching transistor is adjusted. The energy stored in the motor control system is released through the switching transistor in the DC-DC converter by the adjusted current ripple and the target switching frequency, so as to release the energy stored in the motor control system at the fastest rate without adding an additional discharge circuit.

[0105] Reference Figure 6 , Figure 6 This is a schematic diagram of the first process of the fourth embodiment of the active discharge method of the present invention, based on the above. Figure 2 The first embodiment shown presents a fourth embodiment of the active discharge method of the present invention.

[0106] In this embodiment, step S20 includes:

[0107] Step S20': When the motor control system includes a preset discharge circuit, the switching loss value of the DC converter is maintained at the target loss value, and the preset discharge circuit is simultaneously controlled to actively release the voltage of the bus capacitor.

[0108] It should be understood that the energy released by the active discharge method in the first embodiment may result in a slow energy release rate. If the motor control system also includes a preset discharge circuit, the current ripple can be released simultaneously by the switching transistor in the DC converter and the preset discharge circuit, thus avoiding the safety risk of slow energy release when a vehicle collision occurs.

[0109] It should be noted that the preset discharge circuit can be a preset discharge circuit within the motor control system. Compared to the first embodiment without a preset discharge circuit, setting a preset discharge circuit will increase the discharge cost to some extent. However, by releasing the energy stored in the motor control system simultaneously through the preset discharge circuit and the switching transistors in the DC-DC converter, the energy can be released completely at the fastest rate.

[0110] In practical implementation, the electronic control unit can also detect the release process of energy stored in the motor control system to determine whether a preset discharge circuit exists, without using the switching transistors in the DC-DC converter for discharge, and in the event of vehicle power failure or collision. When the motor control system includes a preset discharge circuit, on the one hand, the preset discharge circuit and the switching transistors in the DC-DC converter are controlled to maintain the switching loss value of the DC-DC converter at the target loss value to actively release the energy stored in the motor control system; on the other hand, the energy stored in the motor control system is released through the preset discharge circuit.

[0111] In this embodiment, when a preset discharge circuit exists within the motor control system, the energy stored in the motor control system is released simultaneously through the switching transistor in the DC converter and the preset discharge circuit, thereby further improving the energy release rate within the motor control system.

[0112] Furthermore, this embodiment of the invention also proposes a storage medium storing an active discharge program, which, when executed by a processor, implements the steps of the active discharge method described above.

[0113] In addition, refer to Figure 7 This invention also proposes an active discharge device. In this embodiment, the active discharge device includes:

[0114] Control module 10 is used to control the DC converter to operate with a preset duty cycle and increase the current ripple to a preset current value when the motor control system receives an active discharge command.

[0115] The discharge module 20 is used to maintain the switching loss value of the DC converter at the target loss value corresponding to the preset current value, thereby actively releasing the voltage of the bus capacitor.

[0116] In the first embodiment, an active discharge device is provided. When the motor control system receives an active discharge command, the control module 10 controls the DC-DC converter to operate at a preset duty cycle and increases the current ripple to a preset current value. The discharge module 20 maintains the switching loss value of the DC-DC converter at a target loss value corresponding to the preset current value, thereby actively releasing the voltage of the bus capacitor. In this embodiment, by controlling the DC-DC converter to operate at a preset duty cycle and maintaining the switching loss value of the DC-DC converter at the target loss value corresponding to the preset current value to actively release the voltage of the bus capacitor, the energy stored in the motor control system can be quickly released without adding an additional discharge circuit.

[0117] In one embodiment, the control module 10 is further configured to acquire the operating parameters of the motor control system; determine a first mapping relationship between the output duty cycle of the DC converter and the switching loss value based on the operating parameters; and determine a preset duty cycle of the DC converter based on the first mapping relationship.

[0118] In one embodiment, the control module 10 is further configured to determine the output duty cycle of the DC-DC converter corresponding to the maximum switching loss value according to the first mapping relationship; and use the output duty cycle corresponding to the maximum switching loss value as a preset duty cycle.

[0119] In one embodiment, the discharge module 20 is further configured to adjust the switching frequency of the switching transistor in the DC-DC converter to a target switching frequency; and drive the switching transistor in the DC-DC converter to maintain the switching loss value of the DC-DC converter at the target loss value to actively release the voltage of the bus capacitor according to the target switching frequency.

[0120] In one embodiment, the discharge module 20 is further configured to obtain a second mapping relationship between the switching frequency and the switching loss value; and determine the target switching frequency corresponding to the target loss value based on the second mapping relationship between the switching frequency and the switching loss value.

[0121] In one embodiment, the control module 20 is further configured to obtain a third mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter; obtain a fourth mapping relationship between the switching frequency and the discharge rate of the switching transistor in the DC-DC converter; and determine the target switching frequency of the switching transistor in the DC-DC converter based on the third mapping relationship and the fourth mapping relationship.

[0122] In one embodiment, the control module 20 is further configured to maintain the switching loss value of the DC-DC converter at the target loss value when the motor control system includes a preset discharge circuit, and simultaneously control the preset discharge circuit to actively release the voltage of the bus capacitor.

[0123] Other embodiments or specific implementations of the active discharge device described in this invention can be found in the above-described method embodiments, and will not be repeated here.

[0124] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0125] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the unit claims listing several motor and electronic control systems, several of these motor and electronic control systems may be specifically embodied by the same hardware item. The use of the terms first, second, and third, etc., does not indicate any order and can be interpreted as names.

[0126] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as a read-only memory image (ROM) / random access memory (RAM), magnetic disk, optical disk), and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0127] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. An active discharge method, characterized in that, The active discharge method is applied to a motor control system including a DC-DC converter; The active discharge method includes: Obtain the operating parameters of the motor control system; Based on the operating parameters, a first mapping relationship between the output duty cycle of the DC-DC converter and the switching loss value is determined; The output duty cycle of the DC-DC converter corresponding to the maximum switching loss value is determined based on the first mapping relationship. The output duty cycle corresponding to the maximum switching loss value is used as the preset duty cycle; When the motor control system receives an active discharge command, it controls the DC converter to operate at a preset duty cycle and increases the current ripple to a preset current value. By adjusting the switching frequency of the switching transistors in the DC-DC converter, the switching loss value of the DC-DC converter is maintained at the target loss value corresponding to the preset current value, thereby enabling the voltage of the bus capacitor to be actively released.

2. The active discharge method as described in claim 1, characterized in that, The step of actively releasing the voltage of the bus capacitor by adjusting the switching frequency of the switching transistors in the DC-DC converter to maintain the switching loss value of the DC-DC converter at a target loss value corresponding to a preset current value includes: Adjust the switching frequency of the switching transistors in the DC-DC converter to the target switching frequency; Drive the switching transistors in the DC-DC converter according to the target switching frequency to maintain the switching loss value of the DC-DC converter at the target loss value and actively release the voltage of the bus capacitor.

3. The active discharge method as described in claim 2, characterized in that, Before the step of adjusting the switching frequency of the switching transistors in the DC-DC converter to the target switching frequency, the method further includes: Obtain the second mapping relationship between the switching frequency and the switching loss value; The target switching frequency corresponding to the target loss value is determined based on the second mapping relationship between the switching frequency and the switching loss value.

4. The active discharge method as described in claim 2, characterized in that, The step of adjusting the switching frequency of the switching transistors in the DC-DC converter to the target switching frequency includes, prior to: Obtain a third mapping relationship between the switching loss value and the discharge rate of the switching transistor in the DC-DC converter; Obtain a fourth mapping relationship between the switching frequency and the discharge rate of the switching transistor in the DC-DC converter; The target switching frequency of the switching transistors in the DC-DC converter is determined based on the third and fourth mapping relationships.

5. The active discharge method as described in claim 1, characterized in that, The step of maintaining the switching loss value of the DC converter at the target loss value corresponding to the preset current value, thereby actively releasing the voltage of the bus capacitor, further includes: When the motor control system includes a preset discharge circuit, the switching loss value of the DC-DC converter is maintained at the target loss value, and the preset discharge circuit is simultaneously controlled to actively release the voltage of the bus capacitor.

6. An active discharge device, characterized in that, The active discharge device includes: The control module is used to acquire the operating parameters of the motor control system; The control module is also used to determine a first mapping relationship between the output duty cycle of the DC converter and the switching loss value based on the operating parameters; The control module is also used to determine the output duty cycle of the DC-DC converter corresponding to the maximum switching loss value according to the first mapping relationship; The control module is also used to use the output duty cycle corresponding to the maximum switching loss value as a preset duty cycle; The control module is also used to control the DC converter to operate with a preset duty cycle and increase the current ripple to a preset current value when the motor control system receives an active discharge command. The discharge module is used to actively release the voltage of the bus capacitor by adjusting the switching frequency of the switching transistors in the DC-DC converter to maintain the switching loss value of the DC-DC converter at a target loss value corresponding to a preset current value.

7. A storage medium, characterized in that, The storage medium stores an active discharge program, which, when executed by a processor, implements the steps of the active discharge method as described in any one of claims 1 to 5.

8. A motor control system, characterized in that, The motor control system includes: a DC-DC converter, an inverter, a motor, an energy storage element, and an electronic control unit; the electronic control unit is connected to the control terminal of the switching transistor in the DC-DC converter, the DC-DC converter is connected to the power supply of the motor control system, the energy storage element, and the inverter, and the inverter is connected to the motor; when the electronic control unit operates, it performs the steps of the active discharge method as described in any one of claims 1 to 5.

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