Discharging method of electric drive system and electric drive system

Abstract

The invention provides a discharging method of an electric drive system and the electric drive system.The electric drive system comprises a control module and a booster circuit, the booster circuit comprises a booster module, a first capacitor and a second capacitor, the booster module comprises an inductor unit and a switch unit, the input end of the booster module is connected with the first capacitor in parallel, and the output end of the booster module is connected with the second capacitor in parallel; the inductor unit, the switch unit and the first capacitor form a first loop, the inductor unit, the switch unit, the first capacitor and the second capacitor form a second loop, and the method is applied to a control module and comprises the following steps: generating a discharge control signal in response to a preset discharge control signal; and on-off of the switch unit is controlled based on the discharge control signal, so that the first loop and the second loop are alternately conducted. Therefore, by controlling the first loop and the second loop to be switched on alternately, the second capacitor in the booster circuit can be charged and discharged, so that discharge current flowing back and forth is formed in the inductance unit, and then the second capacitor is powered off.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a discharge method for an electric drive system and an electric drive system. Background Art

[0002] After the electric drive system of a new energy vehicle is started, the bus capacitor of the electric drive system will be charged. After the control drive motor stops running, the bus capacitor needs to be powered off.

[0003] In related technologies, when a drive motor is powered off, the controller calculates its duty cycle, which then controls the motor's switch control module to discharge the charge from the bus capacitor to the motor's windings. However, the duty cycle is calculated based on the phase currents collected by the current sensor and the angular velocity collected by the resolver sensor. If either the current sensor or the resolver sensor fails, the accurate duty cycle cannot be calculated, resulting in a failure to discharge the charge from the bus capacitor.

[0004] Application Contents

[0005] In view of the above problems, the present application provides a discharge method and an electric drive system for an electric drive system. By controlling the alternating conduction of the first circuit and the second circuit, the second capacitor in the boost circuit can be charged and discharged, so as to form a discharge current flowing back and forth in the inductor unit, thereby realizing the power-off of the second capacitor.

[0006] In a first aspect, the present application provides a discharge method for an electric drive system, wherein the electric drive system includes a control module and a boost circuit, the boost circuit includes a boost module, a first capacitor and a second capacitor, the boost module includes an inductor unit and a switch unit, the input end of the boost module is connected in parallel with the first capacitor, and the output end is connected in parallel with the second capacitor, the inductor unit, the switch unit and the first capacitor constitute a first loop, and the inductor unit, the switch unit, the first capacitor and the second capacitor constitute a second loop. The method is applied to the control module, and the method includes: generating a discharge control signal in response to a preset discharge control signal; and controlling the on and off of the switch unit based on the discharge control signal to make the first loop and the second loop alternately conductive.

[0007] In some specific embodiments, the switch unit includes an upper bridge switch unit and a lower bridge switch unit; the step of controlling the on and off of the switch unit to make the first circuit and the second circuit alternately conductive includes: controlling the on and off of the upper bridge switch unit and the lower bridge switch unit of the switch unit to form a discharge cycle; controlling the switch unit to repeat the discharge cycle; wherein the discharge cycle includes a first stage and a second stage, in which the first circuit and the second circuit are sequentially conductive in the first stage, and the inductor unit generates a discharge current in a first direction in the first stage, and the first circuit and the second circuit are sequentially conductive in the second stage, and the inductor unit generates a discharge current in a second direction in the second stage.

[0008] In some specific embodiments, the step of controlling the on / off of the upper bridge switch unit and the lower bridge switch unit of the switch unit to form a discharge cycle includes: controlling the upper bridge switch unit and the lower bridge switch unit to be on / off in a first on / off mode to form a first stage, and then controlling the upper bridge switch unit and the lower bridge switch unit to be on / off in a second on / off mode to form a second stage; or, controlling the upper bridge switch unit and the lower bridge switch unit to be on / off in the second on / off mode to form the second stage, and then controlling the upper bridge switch unit and the lower bridge switch unit to be on / off in the first on / off mode to form the first stage.

[0009] In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in a first on-off mode to form a first stage includes: controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in a first sub-on-off mode to charge the inductor unit through the first capacitor; controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in a second sub-on-off mode to charge the second capacitor through the inductor unit; wherein the first sub-on-off mode and the second sub-on-off mode constitute the first on-off mode.

[0010] In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in a first sub-on-off mode to charge the inductor unit through the first capacitor includes: controlling the upper bridge switch unit to be cut off and the lower bridge switch unit to be turned on to charge the inductor unit through the first capacitor; the step of controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in a second sub-on-off mode to charge the second capacitor through the inductor unit includes: controlling both the upper bridge switch unit and the lower bridge switch unit to be cut off, so that the inductor unit generates a discharge current in a first direction.

[0011] In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in the second on-off mode to form the second stage includes: controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in the third sub-on-off mode to charge the first capacitor through the second capacitor; controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in the fourth sub-on-off mode to charge the first capacitor through the inductor unit; wherein the third sub-on-off mode and the fourth sub-on-off mode constitute the second on-off mode.

[0012] In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in the third sub-on-off mode to charge the first capacitor through the second capacitor includes: controlling the upper bridge switch unit to be turned on and the lower bridge switch unit to be turned off to charge the first capacitor through the second capacitor; the step of controlling the upper bridge switch unit and the lower bridge switch unit to be turned on and off in the fourth sub-on-off mode to charge the first capacitor through the inductor unit includes: controlling both the upper bridge switch unit and the lower bridge switch unit to be turned off, so that the inductor unit generates a discharge current in the second direction.

[0013] In some specific embodiments, the step of generating a discharge control signal in response to a preset discharge control signal includes: determining a target frequency of the discharge control signal based on a target pressure relief duration and a target NVH standard of the electric drive system in response to the preset discharge control signal; obtaining a discharge amplitude step according to a discharge voltage setting parameter, and obtaining a target duty cycle of the discharge control signal through voltage loop PI adjustment and current loop PI adjustment based on the discharge amplitude step; and generating the discharge control signal based on the target frequency and the target duty cycle.

[0014] In some specific embodiments, after the step of generating a discharge control signal based on the target frequency and the target duty cycle, the following steps are included: detecting the current temperature of the first capacitor, the second capacitor, and the inductor unit, and reducing the discharge amplitude step when the current temperature is higher than a preset temperature; detecting the current voltage of the second capacitor, and reducing the discharge amplitude step when the current voltage of the second capacitor is less than a preset voltage; and executing the step of obtaining the target duty cycle of the discharge control signal through voltage loop PI regulation and current loop PI regulation based on the discharge amplitude step.

[0015] A second aspect of the present application provides an electric drive system, comprising: a boost circuit, comprising a boost module, a first capacitor and a second capacitor, the boost module comprising an inductor unit and a switch unit, the input end of the boost module being connected in parallel with the first capacitor, the output end being connected in parallel with the second capacitor, the inductor unit, the switch unit and the first capacitor constituting a first loop, and the inductor unit, the switch unit, the first capacitor and the second capacitor constituting a second loop; a control module, connected to the switch unit, the control module being configured to generate a discharge control signal in response to a preset discharge control signal; and controlling the on and off of the switch unit based on the discharge control signal so that the first loop and the second loop are alternately turned on.

[0016] The present application has at least the following beneficial technical effects: based on the discharge method and electric drive system of the electric drive system provided by the present application, the electric drive system includes a control module and a boost circuit, the boost circuit includes a boost module, a first capacitor and a second capacitor, the boost module includes an inductor unit and a switch unit, the input end of the boost module is connected in parallel with the first capacitor, the output end is connected in parallel with the second capacitor, the inductor unit, the switch unit and the first capacitor constitute a first loop, the inductor unit, the switch unit, the first capacitor and the second capacitor constitute a second loop, the method is applied to the control module, the method includes: in response to a preset discharge control signal, generating a discharge control signal; based on the discharge control signal, controlling the on and off of the switch unit so that the first loop and the second loop are alternately turned on. Therefore, by controlling the first loop and the second loop to be alternately turned on, the second capacitor in the boost circuit can be charged and discharged, so as to form a discharge current flowing back and forth in the inductor unit, thereby realizing the power-off of the second capacitor.

[0017] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the embodiments of the present application, they can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are only used to illustrate the embodiments and are not to be considered as limiting the present application. In addition, the same reference symbols are used to represent the same components throughout the drawings. In the drawings:

[0019] Figure 1 is a structural diagram of an embodiment of the electric drive system provided by the present application;

[0020] Figure 2 is a structural schematic diagram of another embodiment of the electric drive system provided by the present application;

[0021] Figure 3 This is a flow chart of an embodiment of a discharge method for an electric drive system provided by the present application;

[0022] Figure 4 is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application;

[0023] Figure 5 This is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application;

[0024] Figure 6 This is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application;

[0025] Figure 7This is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application;

[0026] Figure 8 This is a schematic diagram of the circuit structure of an embodiment of the electric drive system provided by the present application;

[0027] Figure 9 This is a circuit on-off diagram of an embodiment of the electric drive system provided by the present application;

[0028] Figure 10 This is another circuit on-off diagram of an embodiment of the electric drive system provided by the present application;

[0029] Figure 11 This is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application;

[0030] Figure 12 This is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application;

[0031] Figure 13 This is another circuit on-off diagram of an embodiment of the electric drive system provided by the present application;

[0032] Figure 14 This is another circuit on-off diagram of an embodiment of the electric drive system provided by the present application;

[0033] Figure 15 This is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application;

[0034] Figure 16 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0035] Explanation of the accompanying symbols: electric drive system 100, control module 110, switch module 120, boost module 130, inductor unit 131, first inductor L1, second inductor L2, third inductor L3, switch unit 132, upper bridge switch unit 1321, first switch tube Q1, second switch tube Q2, third switch tube Q3, lower bridge switch unit 1322, fourth switch tube Q4, fifth switch tube Q5, sixth switch tube Q6, first capacitor C1, second capacitor C2, power battery module 140. DETAILED DESCRIPTION

[0036] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0037] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0038] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0039] In this application, "plurality" refers to two or more. "And / or" describes the relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0040] In a first aspect, the present application provides a discharging method for an electric drive system, which is applied to an electric drive system 100 . Figure 1 is a structural diagram of an embodiment of the electric drive system 100 provided in this application. Figure 2 2 is a schematic structural diagram of another embodiment of the electric drive system 100 provided in this application.

[0041] Combine Figure 1 The electric drive system 100 includes a control module 110 and a boost circuit. This method is specifically applied to the control module 110 to control the boost circuit through the control module 110. The purpose is to form a discharge current flowing back and forth in the inductor unit 131 of the boost circuit, thereby achieving power-off of the second capacitor C2. Specifically, the boost circuit includes a boost module 130, a first capacitor C1, and a second capacitor C2. The first input terminal and the second input terminal of the boost module 130 are connected in parallel with the first capacitor C1, and the first output terminal and the second output terminal of the boost module 130 are connected in parallel with the second capacitor C2.

[0042] Combine Figure 2The boost module 130 includes an inductor unit 131 and a switch unit 132. The inductor unit 131, the switch unit 132, and the first capacitor C1 form a first loop, and the inductor unit 131, the switch unit 132, the first capacitor C1, and the second capacitor C2 form a second loop. The switch unit 132 may include one or more switches. The control module 110 can control the conduction between the first loop and the second loop by controlling the on and off of the relevant switches in the switch unit 132.

[0043] Further integration Figure 2 In some specific embodiments, the switch unit 132 includes an upper bridge switch unit 1321 and a lower bridge switch unit 1322. In this case, the upper bridge switch unit 1321 is connected to the inductor unit 131 and the second capacitor C2, respectively, and the lower bridge switch unit 1322 is connected to the inductor unit 131, the first capacitor C1, and the second capacitor C2, respectively. The upper bridge switch unit 1321 and the lower bridge switch unit 1322 are also connected to the control module 110, respectively, and are then controlled by the control module 110. In this case, the inductor unit 131, the lower bridge switch unit 1322, and the first capacitor C1 form a first loop, and the inductor unit 131, the upper bridge switch unit 1321, the first capacitor C1, and the second capacitor C2 form a second loop.

[0044] Further integration Figure 1 as well as Figure 2 The electric drive system 100 also includes a power battery module 140 and a switch module 120. The power battery module 140 is provided with a battery pack as a functional device of the power battery. The power battery module 140 is connected to the boost module 130 and the first capacitor C1 through the switch module 120. When the switch module 120 is closed, the power battery module 140 provides a first driving voltage to the boost module 130. The boost module 130 boosts the first driving voltage and outputs a boosted second driving voltage to the drive motor to enable the drive motor to work. Among them, the first driving voltage will also charge the first capacitor C1. The first capacitor C1 is used to filter and stabilize the output first driving voltage when the boost module 130 boosts the voltage. The second capacitor C2 is the busbar capacitor described in the above-mentioned related art. The second capacitor C2 is used to filter and boost the second driving voltage output by the boost module 130 when the boost module 130 boosts the voltage.

[0045] After the drive motor stops operating, the second capacitor C2 needs to be discharged to reduce the voltage of the second capacitor C2 to below a safe voltage. At this time, the switch module 120 is required to disconnect the power battery module 140 and the boost module 130 according to a preset discharge control signal to prevent the first drive voltage output by the power battery module 140 from being applied to the boost module 130 and affecting the power-off of the second capacitor C2. This also prevents the power battery module 140 from charging the first capacitor C1 and increasing the charge of the first capacitor C1.

[0046] Among them, the preset discharge control signal can be a signal generated by a stop motor command issued by the user, or it can be a signal generated when the current sensor or resolver sensor fails when the user issues a stop command and uses the drive motor armature to discharge, resulting in the inability to discharge through the motor armature.

[0047] Figure 3 This is a flow chart of an embodiment of the discharge method of the electric drive system provided by the present application. Figure 3 , the method comprises the following steps:

[0048] S101: generating a discharge control signal in response to a preset discharge control signal.

[0049] In light of the above, after the vehicle generates a preset discharge control signal, the control module of the electric drive system receives the preset discharge control signal. In response to the preset discharge control signal, the control module generates a discharge control signal that controls the on / off switching of the boost module's switch unit, thereby discharging the second capacitor.

[0050] S102: Based on the discharge control signal, controlling the on and off of the switch unit to make the first circuit and the second circuit alternately conductive.

[0051] After the control module generates the discharge control signal, the control module controls the on / off of the switch unit based on the discharge control signal, thereby causing the first circuit and the second circuit to be alternately turned on to discharge the second capacitor. If the process of alternatingly turning on the first circuit and the second circuit is used as the discharge process of the second capacitor, the control module will continue to generate the discharge control signal during the discharge process.

[0052] It should be understood that the first circuit and the second circuit are alternately turned on, that is, the first circuit and the second circuit are alternately turned on during the discharge process. For example, during the entire discharge process, the alternating conduction can be achieved in the order of the first circuit being turned on (the second circuit being turned off), the second circuit being turned on (the first circuit being turned off), the first circuit being turned on (the second circuit being turned off), and the second circuit being turned on (the first circuit being turned off); or the alternating conduction can be achieved in the order of the first circuit being turned on (the second circuit being turned off), the second circuit being turned on (the first circuit being turned off), the first circuit being turned on (the second circuit being turned off), the second circuit being turned on (the first circuit being turned off), and the first circuit being turned on (the second circuit being turned off), without specific limitation herein.

[0053] Furthermore, the purpose of alternating the first and second loops is to generate a bleeder current flowing back and forth in the inductor unit, thereby causing the inductor unit to generate heat due to the bleeder current, thereby discharging the second capacitor. It should be understood that when the bleeder current is generated in the inductor unit, the impedance of the inductor unit increases, causing the bleeder current to be discharged as heat, thereby discharging the second capacitor.

[0054] Figure 4 FIG. 1 is a flow chart of another embodiment of the discharge method of the electric drive system provided by the present application. Figure 4 , controlling the on and off of the switch unit so that the first circuit and the second circuit are alternately turned on, includes:

[0055] S201: controlling the on and off of the upper bridge switch unit and the lower bridge switch unit of the switch unit to form a discharge cycle.

[0056] In this embodiment, the on-off control of the switch unit, specifically the on-off control of the upper bridge switch unit and the lower bridge switch unit of the switch unit, is to form a discharge cycle.

[0057] The discharge cycle includes a first phase and a second phase. During the first phase, the first and second circuits are sequentially connected. During the second phase, the first and second circuits are similarly connected. It should be understood that during the first phase, the first and second circuits may be connected sequentially, either with the first circuit connected first and the second circuit connected second, or with the second circuit connected first and the first circuit connected second. This embodiment does not impose any specific limitations. The same applies to the conduction method during the second phase.

[0058] The inductor unit generates a discharge current in a first direction during the first phase and a discharge current in a second direction during the second phase, wherein the first direction and the second direction are opposite to each other. Therefore, a current can flow back and forth in the inductor unit during the discharge cycle.

[0059] S202: Control the switch unit to repeat the discharge cycle.

[0060] Repeatedly controlling the switch unit can repeat the above-mentioned discharge cycle. Because a current can flow back and forth in each discharge cycle, a continuous back and forth discharge current can be formed in the inductor unit when the discharge cycle is repeated.

[0061] Figure 5 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0062] Combine Figure 5 In some specific embodiments, the step of controlling the on / off of the upper bridge switch unit and the lower bridge switch unit of the switch unit to form a discharge cycle, i.e., the above-mentioned step S201, includes:

[0063] S301: controlling the upper bridge switch unit and the lower bridge switch unit to switch in a first switching mode to form a first stage, and then controlling the upper bridge switch unit and the lower bridge switch unit to switch in a second switching mode to form a second stage.

[0064] It should be understood that the order of steps in this embodiment does not limit the order of execution of the steps. The two steps are parallel steps, and one of them can be selected for execution according to actual circumstances.

[0065] The first on-off mode and the second on-off mode are both control modes for controlling the upper and lower bridge switch units, and are pre-set based on actual needs. When the upper and lower bridge switch units are controlled in the first on-off mode, the corresponding stage is the first stage; when the upper and lower bridge switch units are controlled in the second on-off mode, the corresponding stage is the second stage.

[0066] At this time, in a discharge cycle, the inductor unit first generates a current in a first direction and then generates a current in a second direction.

[0067] S302: Control the upper bridge switch unit and the lower bridge switch unit to switch in the second switching mode to form a second stage, and then control the upper bridge switch unit and the lower bridge switch unit to switch in the first switching mode to form a first stage.

[0068] Different from the above steps, in the corresponding discharge cycle, the second stage is located before the first stage, that is, the current in the second direction is generated first and then the current in the first direction is generated.

[0069] Figure 6 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0070] Combine Figure 6 In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to switch on and off in the first switching mode to form the first stage includes:

[0071] S401: Control the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a first sub-on and off mode, so as to charge the inductor unit through the first capacitor.

[0072] This embodiment specifically describes the first on-off mode, that is, the first on-off mode includes a first sub-on-off mode and a second sub-on-off mode. At this time, the stage corresponding to the first sub-on-off mode and the stage corresponding to the second sub-on-off mode together constitute the first stage.

[0073] It should be understood that the first sub-on-off mode defined in this embodiment is used to charge the inductor unit through the first capacitor. At this time, the first capacitor is discharged and the inductor unit is charged.

[0074] S402: Control the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a second sub-on and off mode, so as to charge the second capacitor through the inductor unit.

[0075] It should be understood that the second sub-on-off mode defined in this embodiment is used to charge the second capacitor through the inductor unit. At this time, the inductor unit is discharged and the second capacitor is charged.

[0076] Through the above two steps, the discharge of the first capacitor and the charging of the second capacitor are finally achieved. In combination with the above content, the first on-off mode corresponds to the first stage, and during the first stage, the first circuit and the second circuit are sequentially turned on. In this case, the above first sub-on-off mode can correspond to one of the first circuit and the second circuit being turned on, and the second sub-on-off mode can correspond to the other of the first circuit and the second circuit being turned on, without specific limitation here.

[0077] Figure 7 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0078] Combine Figure 7 In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in the first sub-on / off mode to charge the inductor unit through the first capacitor includes:

[0079] S501: Control the upper bridge switch unit to be turned off and the lower bridge switch unit to be turned on, so as to charge the inductor unit through the first capacitor.

[0080] Figure 8 1 is a schematic diagram of the circuit structure of an embodiment of the electric drive system 100 provided in this application.

[0081] In some specific embodiments, the boost module is an N-phase staggered parallel Boost boost module, and the number of phases of the N-phase staggered parallel Boost boost module can be selected according to actual needs. Figure 8 , showing that the N-phase staggered parallel Boost module is a three-phase staggered parallel Boost module. Among them, the inductor unit 131 includes: a first inductor L1, a second inductor L2 and a third inductor L3; the upper bridge switch unit 132 includes: a first switch tube Q1, a second switch tube Q2 and a third switch tube Q3; the lower bridge switch unit 133 includes: a fourth switch tube Q4, a fifth switch tube Q5 and a sixth switch tube Q6; the first end of the first inductor L1 is respectively connected to the first end of the first capacitor C1, the first end of the second inductor L2 and the first end of the third inductor L3, the second end of the first inductor L1 is respectively connected to the third end of the first switch tube Q1 and the first end of the fourth switch tube Q4; the second end of the second inductor L2 is respectively connected to the third end of the second switch tube Q2 and the fifth switch tube Q5 The first end of the third inductor L3 is connected to the third end of the third switch tube Q3 and the first end of the sixth switch tube Q6 respectively; the first end of the first switch tube Q1 is connected to the first end of the second switch tube Q2, the first end of the third switch tube Q3, and the first end of the second capacitor C2 respectively; the third end of the fourth switch tube Q4 is connected to the second end of the first capacitor C1, the third end of the fifth switch tube Q5, the third end of the sixth switch tube Q6, and the second end of the second capacitor C2 respectively; the second ends of the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5, and the sixth switch tube Q6 are respectively connected to the control module 110.

[0082] It should be understood that each switch includes an IGBT (Insulated Gate Bipolar Transistor) and a freewheeling diode. Controlling the switch is essentially controlling the IGBT. If boost module 130 is a single-phase interleaved parallel boost module, then boost module 130 only includes one inductor, one switch connected to the inductor in the upper-bridge switch unit 1321, and a corresponding switch in the lower-bridge switch unit 1322. For example, a corresponding structure includes: a first inductor L1, a first switch Q1, and a fourth switch Q4.

[0083] Continue to combine Figure 8The power battery module 140 may include a power battery BT1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth capacitor C4, and a fifth capacitor C5. The switch module 120 may include a first switch K1. The positive electrode of the power battery BT1 is connected to the first end of the first resistor R1, the second end of the first resistor R1 is respectively connected to the first end of the second resistor R2 and the first end of the fourth capacitor C4, the second end of the second resistor R2 is connected to the first end of the third resistor R3, the second end of the fourth capacitor C4, and the first end of the fifth capacitor C5, the second end of the third resistor R3 is respectively connected to the second end of the fifth capacitor C5 and the first end of the first switch K1, and the second end of the first switch K1 is respectively connected to the first end of the first inductor L1, the first end of the second inductor L2, and the second end of the third inductor L3.

[0084] Figure 9 1 is a circuit on-off diagram of an embodiment of the electric drive system 100 provided in the present application.

[0085] Combine Figure 9 In this step, the upper bridge switch unit 1321 is controlled to be turned off and the lower bridge switch unit 1322 is controlled to be turned on, so as to charge the inductor unit through the first capacitor.

[0086] Specifically, when the upper bridge switch unit 1321 and the lower bridge switch unit 1322 are turned on, the first switch tube Q1, the second switch tube Q2, and the third switch tube Q3 are turned off, and the fourth switch tube Q4, the fifth switch tube Q5, and the sixth switch tube Q6 are turned on. At this time, the inductor unit 131 generates a current in a first direction, that is, generates a discharge current in a first direction. For the specific direction of the discharge current, please refer to Figure 9 As shown by the arrow in . At this time, the first capacitor C1 charges the inductor unit 131, and the current flows back to the inductor unit 131 through the low-bridge switch unit 1322 and the first capacitor C1. During this process, the discharge current flows through the inductor unit 131, causing the impedance of the inductor unit 131 to change. The first inductor L1, the second inductor L2, and the third inductor L3 convert the discharge current into heat for dissipation, thereby reducing the voltage of the first capacitor C1, thereby also achieving the discharge of the voltage of the first capacitor C1.

[0087] The step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in the second sub-on and off mode to charge the second capacitor through the inductor unit includes:

[0088] S502: Control the upper bridge switch unit and the lower bridge switch unit to be turned off, so that the inductor unit generates a discharge current in a first direction.

[0089] Figure 10 This is another circuit on-off diagram of an embodiment of the electric drive system 100 provided in this application.

[0090] Combine Figure 10 , both the upper bridge switch unit 1321 and the lower bridge switch unit 1322 are turned off, that is, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5, and the sixth switch tube Q6 are all turned off. At this time, the discharge current can flow out in the first direction through the inductor unit 131, pass through the diodes of the first switch tube Q1, the second switch tube Q2, and the third switch tube Q3, and then flow back to the inductor unit 131 through the second capacitor C2 and the first capacitor C1. For the specific current flow direction, please refer to Figure 10 It should be understood that by controlling the upper bridge switch unit 1321 and the lower bridge switch unit 1322 to be turned off, the lower bridge switch unit 1322 can be prevented from being continuously turned on and generating heat, thereby causing damage to the lower bridge switch unit 1322.

[0091] In summary, the discharge current can be generated through the above two steps, and the direction of the generated discharge current is the first direction.

[0092] Figure 11 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0093] Combine Figure 11 In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to switch on and off in the second switching mode to form the second stage includes:

[0094] S601: Control the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a third sub-on and off mode, so as to charge the first capacitor through the second capacitor.

[0095] It should be understood that the third and fourth sub-on / off modes together constitute the second on / off mode, in which a discharge current in the second direction is generated. In this case, the phase corresponding to the third and fourth sub-on / off modes together constitute the second phase.

[0096] It should be understood that the third sub-on-off mode defined in this embodiment is used to charge the first capacitor through the second capacitor. At this time, the second capacitor is discharged and the first capacitor is charged.

[0097] S602: Control the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a fourth sub-on and off mode, so as to charge the first capacitor through the inductor unit.

[0098] It should be understood that the fourth sub-on-off mode defined in this embodiment is used to charge the first capacitor through the inductor unit.

[0099] Figure 12 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0100] Combine Figure 12 In some specific embodiments, the step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a third sub-on / off mode to charge the first capacitor through the second capacitor includes:

[0101] S701: Control the upper bridge switch unit to be turned on and the lower bridge switch unit to be turned off, so as to charge the first capacitor through the second capacitor.

[0102] Figure 13 This is another circuit on-off diagram of an embodiment of the electric drive system provided in this application.

[0103] Combine Figure 13 , controlling the high-bridge switch unit 1321 to conduct, specifically controlling the first switch Q1, the second switch Q2, and the third switch Q3 to conduct, and turning off the low-bridge switch unit 1322, specifically controlling the fourth switch Q4, the fifth switch Q5, and the sixth switch Q6 to turn off. At this time, the second capacitor C2 discharges, and the discharge current flows through the inductor unit 131 in the second direction, charging the inductor unit 131 and the first capacitor C1.

[0104] At this time, the discharge current flows through the first inductor L1, the second inductor L2 and the third inductor L3 respectively. The specific flow direction of the discharge current is as follows: Figure 4 As shown by the arrows in FIG, the first inductor L1, the second inductor L2, and the third inductor L3 convert the discharge current into heat for discharge. It should be noted that the first switching transistor Q1, the second switching transistor Q2, and the third switching transistor Q3 have internal resistance, which also generates a certain amount of heat, which can discharge the voltage of the second capacitor C2.

[0105] The step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a fourth sub-on and off mode to charge the first capacitor through the inductor unit includes:

[0106] S702: Control the upper bridge switch unit and the lower bridge switch unit to be turned off, so that the inductor unit generates a discharge current in a second direction.

[0107] Figure 14 This is another circuit on-off diagram of an embodiment of the electric drive system 100 provided in this application.

[0108] Combine Figure 14When both the upper bridge switch unit 1321 and the lower bridge switch unit 1322 are turned off, that is, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, the fourth switch tube Q4, the fifth switch tube Q5, and the sixth switch tube Q6 are all turned off. At this time, the inductor unit 131 generates a discharge current in the second direction. The discharge current can flow through the inductor unit 131 to the first capacitor C1, and then flow back to the inductor unit 131 through the diodes of the fourth switch tube Q4, the fifth switch tube Q5, and the sixth switch tube Q6. The inductor unit 131 charges the first capacitor C1. It should be understood that by turning off the upper bridge switch unit 1321 and the lower bridge switch unit 1322, and using the diode of the lower bridge switch unit 133 to pass the discharge current, the upper bridge switch unit 132 can be prevented from being continuously turned on and overheating, which could damage the upper bridge switch unit 132.

[0109] Figure 15 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0110] Combine Figure 15 In some specific embodiments, in response to a preset discharge control signal, the step of generating a discharge control signal, i.e., the above-mentioned step S101, includes:

[0111] S801: In response to a preset discharge control signal, a target frequency of the discharge control signal is determined according to a target pressure relief duration and a target NVH standard of the electric drive system.

[0112] The target pressure relief time is the target time for the voltage of the second capacitor to drop to within the safe voltage. The target pressure relief time can be preset according to actual needs. In order to quickly power off the second capacitor, the target pressure relief time can be set to be shorter.

[0113] It should be understood that based on the above control method, the electric drive system will generate a certain amount of noise during the de-energization process of the second capacitor, which will affect the vehicle's NVH (Noise, Vibration, Harshness) performance. Therefore, it is necessary to set a target NVH standard for the electric drive system. When the electric drive system meets the target NVH standard, the vehicle's NVH performance will be improved.

[0114] Among them, under the target pressure relief time, there will be a corresponding frequency range of the discharge control signal. For example, in order to meet the target pressure relief time, the minimum frequency of the frequency range should be greater than a certain frequency. Under the target NVH standard, there will also be a corresponding frequency range of the discharge control signal. For example, in order to meet the target NVH standard, the highest frequency of the frequency range should be less than a certain frequency. Therefore, through these two factors, a frequency range can be determined, and a frequency can be selected from the frequency range as the target frequency. For example, in some application scenarios, a frequency of 20k can be selected as the target frequency.

[0115] In some application scenarios, before this step is implemented, the voltage of the first capacitor, the voltage of the second capacitor, the current in the inductor unit and the temperature of the switch tube are also detected to calculate whether a fault has occurred. If no fault has occurred, this step is executed.

[0116] S802: Obtaining a discharge amplitude step according to the discharge voltage setting parameter, and obtaining a target duty cycle of the discharge control signal through voltage loop PI regulation and current loop PI regulation based on the discharge amplitude step.

[0117] It should be understood that during the power-off process of the second capacitor achieved through the above-mentioned control method, the voltage after the second capacitor discharges to the first capacitor, and the voltage after the first capacitor discharges to the second capacitor, is the discharge voltage, and the discharge voltage setting parameters can be set according to the preset strategy.

[0118] After obtaining the discharge voltage setting parameters, the discharge amplitude step size can be determined based on the system's maximum discharge capacity limit. The discharge amplitude step size is the voltage discharge amplitude step size, which represents the amount of voltage discharge per unit time. The larger the discharge amplitude step size, the faster the voltage discharge.

[0119] After determining the discharge amplitude step size, the target duty cycle of the discharge control signal can be directly determined through voltage and current loop PI regulation. These two loops work together through PI regulators, balancing dynamic response and steady-state accuracy. This is the core control strategy for stable operation of power electronics systems. The voltage loop calculates the required current reference value (i.e., the current required to maintain voltage stability) based on the output voltage deviation. The current loop receives this reference value and rapidly adjusts the actual current to track the reference value. Precise current control ultimately achieves voltage stability.

[0120] S803: Generate a discharge control signal based on the target frequency and the target duty cycle.

[0121] After obtaining the target frequency and target duty cycle of the discharge control signal, the discharge control signal can be directly generated. In this case, the discharge control signal is a PWM signal.

[0122] Figure 16 This is a flow chart of another embodiment of the discharge method of the electric drive system provided in this application.

[0123] Combine Figure 16 In some specific embodiments, after the step of generating the discharge control signal based on the target frequency and the target duty cycle, that is, after the above step S803, the following steps are included:

[0124] S901: Detecting current temperatures of the first capacitor, the second capacitor, and the inductor unit, and reducing the discharge amplitude step when the current temperature is higher than a preset temperature.

[0125] It should be understood that during the discharge process, the temperature of the first capacitor, the second capacitor, and the inductor unit should not be too high, otherwise it will cause damage to the first capacitor, the second capacitor, and the inductor unit. The preset temperature can be set according to actual needs, wherein the first capacitor, the second capacitor, and the inductor unit can each correspond to a preset temperature. When the current temperature of any of the first capacitor, the second capacitor, and the inductor unit is higher than the corresponding preset temperature, it indicates that the degree of discharge needs to be reduced. In this case, the degree of discharge is reduced by reducing the discharge amplitude step size.

[0126] S902: Detect the current voltage of the second capacitor, and reduce the discharge amplitude step when the current voltage of the second capacitor is less than a preset voltage.

[0127] It should be understood that step S901 and step S902 are parallel steps, describing two ways of reducing the step size of the discharge amplitude.

[0128] In this step, the voltage of the second capacitor is detected during the power-off process. The preset voltage can be set according to actual needs. The preset voltage is lower than the initial voltage of the second capacitor at the beginning of the power-off process, but higher than the safety voltage of the second capacitor, and the difference between the initial voltage and the current voltage is greater than a certain voltage value. When the current voltage of the second capacitor is lower than the preset voltage, it means that the voltage of the second capacitor has dropped to a certain extent. At this time, in order to ensure that related components are not damaged during the power-off process, the degree of discharge is reduced by reducing the discharge amplitude step.

[0129] S903: Executing a step of obtaining a target duty cycle of a discharge control signal through voltage loop PI regulation and current loop PI regulation based on the discharge amplitude step.

[0130] It should be understood that after reducing the discharge amplitude step, it is necessary to obtain the target duty cycle of the discharge control signal through voltage loop PI regulation and current loop PI regulation, and then determine the discharge control signal based on the new target duty cycle.

[0131] A second aspect of the present application provides an electric drive system, comprising: a boost circuit, comprising a boost module, a first capacitor and a second capacitor, the boost module comprising an inductor unit and a switch unit, the input end of the boost module being connected in parallel with the first capacitor, the output end being connected in parallel with the second capacitor, the inductor unit, the switch unit and the first capacitor constituting a first loop, and the inductor unit, the switch unit, the first capacitor and the second capacitor constituting a second loop; a control module, connected to the switch unit, the control module being configured to generate a discharge control signal in response to a preset discharge control signal; and controlling the on and off of the switch unit based on the discharge control signal so that the first loop and the second loop are alternately turned on.

[0132] Among them, for the above modules and related control methods, please refer to the relevant content of the above embodiments, and no further details will be given here.

[0133] The above content is only a preferred exemplary embodiment of the present application and is not intended to limit the implementation scheme of the present application. Ordinary technicians in this field can easily make corresponding changes or modifications based on the main ideas and spirit of the present application. Therefore, the scope of protection of the present application shall be based on the scope of protection required by the claims.

Claims

1. A discharge method for an electric drive system, characterized in that: The electric drive system includes a control module and a boost circuit, the boost circuit includes a boost module, a first capacitor, and a second capacitor, the boost module includes an inductor unit and a switch unit, the input end of the boost module is connected in parallel with the first capacitor, and the output end is connected in parallel with the second capacitor, the inductor unit, the switch unit, and the first capacitor constitute a first loop, and the inductor unit, the switch unit, the first capacitor, and the second capacitor constitute a second loop. The method is applied to the control module, and the method includes: generating a discharge control signal in response to a preset discharge control signal; Based on the discharge control signal, the switching unit is controlled to be turned on and off, so that the first loop and the second loop are alternately turned on.

2. The discharge method according to claim 1, wherein: The switch unit includes an upper bridge switch unit and a lower bridge switch unit; The step of controlling the on and off of the switch unit so that the first loop and the second loop are alternately turned on includes: Controlling the on and off of the upper bridge switch unit and the lower bridge switch unit of the switch unit to form a discharge cycle; controlling the switch unit to repeat the discharge cycle; The discharge cycle includes a first stage and a second stage. During the first stage, the first loop and the second loop are sequentially turned on, and the inductor unit generates a discharge current in a first direction. During the second stage, the first loop and the second loop are sequentially turned on, and the inductor unit generates a discharge current in a second direction.

3. The discharge method according to claim 2, characterized in that: The step of controlling the on and off of the upper bridge switch unit and the lower bridge switch unit of the switch unit to form a discharge cycle includes: Controlling the upper bridge switch unit and the lower bridge switch unit to switch in a first on-off mode to form the first stage, and then controlling the upper bridge switch unit and the lower bridge switch unit to switch in a second on-off mode to form the second stage; or, The upper bridge switch unit and the lower bridge switch unit are controlled to be switched in the second switching mode to form the second stage, and then the upper bridge switch unit and the lower bridge switch unit are controlled to be switched in the first switching mode to form the first stage.

4. The discharge method according to claim 3, characterized in that: The step of controlling the upper bridge switch unit and the lower bridge switch unit to switch on and off in the first switching mode to form the first stage includes: Controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a first sub-on and off mode, so as to charge the inductor unit through the first capacitor; Controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a second sub-on and off mode, so as to charge the second capacitor through the inductor unit; The first sub-on-off mode and the second sub-on-off mode constitute the first on-off mode.

5. The discharge method according to claim 4, characterized in that: The step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a first sub-on and off mode so as to charge the inductor unit through the first capacitor includes: Controlling the upper bridge switch unit to be turned off and the lower bridge switch unit to be turned on, so as to charge the inductor unit through the first capacitor; The step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a second sub-on and off mode so as to charge the second capacitor through the inductor unit includes: The upper bridge switch unit and the lower bridge switch unit are both controlled to be turned off, so that the inductor unit generates a discharge current in the first direction.

6. The discharge method according to claim 3, characterized in that: The step of controlling the upper bridge switch unit and the lower bridge switch unit to switch on and off in the second switching mode to form the second stage includes: controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a third sub-on-off mode, so as to charge the first capacitor through the second capacitor; Controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a fourth sub-on and off mode, so as to charge the first capacitor through the inductor unit; The third sub-on-off mode and the fourth sub-on-off mode constitute the second on-off mode.

7. The discharge method according to claim 6, characterized in that: The step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a third sub-on and off mode so as to charge the first capacitor through the second capacitor includes: controlling the upper bridge switch unit to be turned on and the lower bridge switch unit to be turned off, so as to charge the first capacitor through the second capacitor; The step of controlling the upper bridge switch unit and the lower bridge switch unit to be switched on and off in a fourth sub-on and off mode to charge the first capacitor through the inductor unit includes: The upper bridge switch unit and the lower bridge switch unit are both controlled to be turned off, so that the inductor unit generates the discharge current in the second direction.

8. The discharge method according to claim 1, wherein: In response to a preset discharge control signal, the step of generating a discharge control signal comprises: In response to a preset discharge control signal, a target frequency of the discharge control signal is determined according to a target pressure relief duration and a target NVH standard of the electric drive system; Obtaining a discharge amplitude step length according to a discharge voltage setting parameter, and obtaining a target duty cycle of the discharge control signal through voltage loop PI regulation and current loop PI regulation based on the discharge amplitude step length; The discharge control signal is generated based on the target frequency and the target duty cycle.

9. The discharge method according to claim 8, characterized in that: After the step of generating the discharge control signal based on the target frequency and the target duty cycle, the method further comprises: detecting current temperatures of the first capacitor, the second capacitor, and the inductor unit, and reducing the discharge amplitude step when the current temperatures are higher than a preset temperature; detecting a current voltage of the second capacitor, and reducing the discharge amplitude step when the current voltage of the second capacitor is lower than a preset voltage; The step of obtaining a target duty cycle of the discharge control signal through voltage loop PI regulation and current loop PI regulation based on the discharge amplitude step is performed.

10. An electric drive system, characterized in that: include: A boost circuit, comprising a boost module, a first capacitor, and a second capacitor, the boost module comprising an inductor unit and a switch unit, the first capacitor being connected in parallel to the input end of the boost module and the second capacitor being connected in parallel to the output end thereof, the inductor unit, the switch unit, and the first capacitor forming a first loop, and the inductor unit, the switch unit, the first capacitor, and the second capacitor forming a second loop; A control module is connected to the switch unit, and is used to generate a discharge control signal in response to a preset discharge control signal; based on the discharge control signal, the control module controls the on and off of the switch unit to make the first circuit and the second circuit alternately conductive.

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