Direct-current bus capacitor discharging method and device, electronic equipment and medium

Abstract

The invention provides a direct-current bus capacitor discharging method and device, electronic equipment and a readable storage medium. The method comprises the following steps: acquiring the pulse width of a pulse width modulation signal of a first switch tube of at least one bridge arm; the second switch tube of the bridge arm is conducted in the discharging process, and the following steps are iteratively executed: the target discharging slope at the current sampling moment is determined according to the target discharging time and the target discharging voltage; determining an actual discharge slope according to the voltage drop value of the DC bus capacitor; updating the pulse width of the switching pulse width modulation signal according to the target discharge slope and the actual discharge slope; and inputting the updated pulse width modulation signal to a first switch tube on the bridge arm so as to discharge the direct current bus capacitor. Through more accurate closed-loop control, the power consumption of the power tube in the discharging process can be basically constant, and the temperature rise of the power tube in the discharging process is effectively reduced, so that the power tube is protected, the service life of the power tube is prolonged, and additional cost does not need to be increased.

Description

Technical Field

[0001] The present invention relates to the field of new energy vehicle control technology, and in particular to a DC bus capacitor discharge method, device, electronic equipment and readable storage medium. Background Art

[0002] As the power level of new energy vehicles continues to increase, the voltage level of the inverter DC bus is also increasing. The higher and higher DC bus voltage is bound to bring potential safety problems. In the fault and shutdown state, the excessively high DC bus voltage poses a great safety hazard. For example, after a vehicle fails, maintenance personnel open the cover for maintenance, and after a vehicle collision, the high-voltage bus may be exposed. Under these conditions, maintenance personnel have the opportunity to touch the DC bus, causing personal safety issues. Therefore, how to quickly and safely complete the discharge of the DC bus capacitor in the shutdown or fault state is becoming one of the technical problems that need to be solved in the design of new energy vehicles.

[0003] In order to solve the above problems, the inverter's own power tube (SIC / IGBT) is usually used to discharge the DC bus capacitor, such as Figure 1 As shown, Figure 1 This is a topological diagram of a specific example of a bridge inverter in the related art. Using the inverter's own power tubes (such as the power tubes Q01, Q02 and / or Q03 of the upper bridge arm) for discharge has the advantages of fast discharge speed, low price cost and wide application occasions, and has been widely used in some inverter products. In the related art, there are mainly two active discharge solutions using bridge arm direct discharge:

[0004] One of them is to use an open-loop control scheme to discharge the DC bus capacitor C. The basic principle of this scheme is: keep the lower tube (the power tube of the lower bridge arm, such as the power tube Q04) / upper tube (the power tube of the upper bridge arm, such as the power tube Q01) always on, and calibrate the drive pulse width of the upper tube (such as the power tube Q01) / lower tube (power tube Q04) based on different temperatures and different bus voltages. At the beginning of discharge, the corresponding preset pulse width is determined according to the correspondence between the pre-calibrated temperature and bus voltage and the drive pulse width, as well as the sampled temperature and sampled bus voltage, to discharge. However, in actual applications, it is found that power tube dispersion (including but not limited to performance differences of power tubes of different buses due to differences in manufacturing processes, materials, etc.) may cause discharge timeout or overheating of the power tube or even damage to the power tube.

[0005] Another is a closed-loop control solution based on discharge current. The basic principle of this solution is: using an additional discharge current sampling circuit, according to the bus voltage feedback value, setting the reference current, and controlling the driving pulse width of the upper bridge arm in real time to achieve discharge. The disadvantage of this solution is that it requires an additional discharge current sampling circuit, which increases the cost and has a greater impact on the thermal safety of the power tube.

[0006] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide a DC bus capacitor discharge method, device, electronic device and readable storage medium. The present invention can achieve basically constant power consumption of the power tube during the discharge process and effectively reduce the temperature rise of the power tube during the discharge process through more precise closed-loop control of the DC bus capacitor discharge pulse width, thereby protecting the power tube and prolonging its life without increasing additional costs.

[0008] In order to achieve the above object, the present invention is implemented by the following technical scheme, a DC bus capacitor discharge method, the DC bus capacitor is connected in parallel with the input end of a bridge inverter, the bridge inverter includes at least one bridge arm, each of the bridge arms includes a first switch tube and a second switch tube; characterized in that the DC bus capacitor discharge method includes:

[0009] Acquire the pulse width of a pulse width modulation signal of a first switch tube of at least one of the bridge arms;

[0010] During the DC bus capacitor discharge process, the second switch tube of the bridge arm is turned on, and the following steps are iteratively performed:

[0011] Determine the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage; the target discharge slope includes the voltage drop rate of the DC bus capacitor;

[0012] Determining an actual discharge slope according to a voltage drop value of the DC bus capacitor;

[0013] updating the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope;

[0014] The updated pulse width modulation signal is input to the first switch tube on the bridge arm to discharge the DC bus capacitor.

[0015] Optionally, determining the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage includes:

[0016] The target discharge slope at the current sampling moment is determined according to the target discharge time, the target discharge voltage, and the discharge duration of the discharge process.

[0017] Optionally, the target discharge voltage includes a pre-calibrated discharge voltage preset value or an initial bus voltage before the DC bus capacitor is discharged.

[0018] Optionally, determining the actual discharge slope according to the voltage drop value of the DC bus capacitor includes:

[0019] Calculating the voltage difference between the DC bus capacitor at the current sampling moment and the previous sampling moment;

[0020] Calculating the time difference between the current sampling moment and the previous sampling moment;

[0021] The actual discharge slope is calculated according to the voltage difference and the time difference.

[0022] Optionally, updating the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope includes:

[0023] Calculating a difference between an absolute value of the actual discharge slope and an absolute value of the target discharge slope;

[0024] If the difference is greater than a first preset threshold, reducing the pulse width of the switch pulse width modulation signal;

[0025] If the difference is smaller than a second preset threshold, the pulse width of the switch pulse width modulation signal is increased.

[0026] Optionally, updating the pulse width of the switch pulse width modulation signal includes:

[0027] According to the difference, the pulse width of the switch pulse width modulation signal is updated by accumulating / subtracting according to a preset step size or by adopting a PI control method.

[0028] Optionally, determining the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage includes:

[0029] The target discharge slope at the current sampling moment is determined according to the target discharge time, the target discharge voltage, and the current voltage value of the bus capacitor at the current sampling moment.

[0030] In order to achieve the above object, the present invention further provides a discharge control device for a DC bus capacitor, wherein the DC bus capacitor is connected in parallel with an input end of a bridge inverter, wherein the bridge inverter comprises at least one bridge arm, and each bridge arm comprises a first switch tube and a second switch tube. The discharge control device comprises:

[0031] A discharge control unit, configured to obtain a pulse width of a pulse width modulation signal of a first switch tube of at least one of the bridge arms; and to turn on a second switch tube of the bridge arm during the discharge of the DC bus capacitor;

[0032] A target discharge slope acquisition unit is configured to determine a target discharge slope at a current sampling moment according to a target discharge time and a target discharge voltage; the target discharge slope includes a voltage drop rate of the DC bus capacitor;

[0033] An actual discharge slope acquisition unit is configured to determine an actual discharge slope according to a voltage drop value of the DC bus capacitor;

[0034] a pulse width adjustment unit, configured to update the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope;

[0035] The discharge control unit is further used to input the updated pulse width modulation signal to the first switch tube on the bridge arm to discharge the DC bus capacitor.

[0036] In order to achieve the above-mentioned purpose, the present invention also provides an electronic device, which includes a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, any of the above-mentioned DC bus capacitor discharge methods is implemented.

[0037] In order to achieve the above object, the present invention further provides a readable storage medium, characterized in that a computer program is stored in the readable storage medium, and when the computer program is executed by a processor, any of the above-mentioned DC bus capacitor discharge methods is implemented.

[0038] Compared with the prior art, the DC bus capacitor discharge method, device, electronic device and readable storage medium provided by the present invention have the following advantages:

[0039] The DC bus capacitor discharge method provided by the present invention determines the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage during the DC bus capacitor discharge process; and determines the actual discharge slope according to the voltage drop value of the DC bus capacitor; and then updates the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope. Thus, the present invention can realize more accurate closed-loop control of the DC bus capacitor discharge pulse width, which can not only make the entire discharge process in a controllable state, but also ensure that the discharge time meets the requirements, and at the same time realize that the power consumption of the power tube during the discharge process is basically constant, thereby effectively reducing the temperature rise of the power tube during the discharge process, ensuring the thermal safety of the power tube, and better protecting the power tube to increase its life. Furthermore, the voltage drop value of the DC bus capacitor can be obtained by reusing the existing voltage information acquisition method, thereby eliminating the need for an additional discharge current sampling circuit and increasing the additional cost, which can not only significantly reduce the cost, but also effectively reduce the area of ​​the control circuit, thereby improving the overall power density.

[0040] Since the discharge control device, electronic device and readable storage medium for the DC bus capacitor provided by the present invention belong to the same inventive concept as the DC bus capacitor discharge method provided by the present invention, the discharge control device, electronic device and readable storage medium of the DC bus capacitor provided by the present invention at least have all the advantages of the DC bus capacitor discharge method provided by the present invention. For details of the beneficial effects of the discharge control device, electronic device and readable storage medium of the DC bus capacitor provided by the present invention, please refer to the above description of the beneficial effects of the DC bus capacitor discharge method provided by the present invention, and no further details will be given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a topological structure of a specific example of a bridge inverter in the related art;

[0042] Figure 2 This is a schematic diagram of the direct discharge principle of the bridge inverter;

[0043] Figure 3 A schematic diagram of the overall flow of a DC bus capacitor discharge method provided in Embodiment 1 of the present invention;

[0044] Figure 4 A schematic diagram of the principle of a DC bus capacitor discharge method provided in Embodiment 1 of the present invention;

[0045] Figure 5 A schematic diagram of the principle of a DC bus capacitor discharge method provided in Embodiment 2 of the present invention;

[0046] Figure 6A schematic block diagram of a discharge control device for a DC bus capacitor provided in Embodiment 3 of the present invention;

[0047] Figure 7 A schematic diagram of the block structure of an electronic device provided in Embodiment 4 of the present invention;

[0048] The reference numerals are as follows:

[0049] Power tube-Q01, Q02, Q03;

[0050] Bus capacitor-C, bridge inverter-100, bridge arms-110, 120, 130, first switch tubes-Q11, Q21, Q31; second switch tubes-Q12, Q22, Q32;

[0051] Discharge control unit-210, target discharge slope acquisition unit-220, actual discharge slope acquisition unit-230, pulse width adjustment unit-240;

[0052] Processor-310, memory-320, communication interface-330, communication bus-240. DETAILED DESCRIPTION

[0053] The DC bus capacitor discharge method, device, electronic device and readable storage medium proposed in the present invention are further described in detail below in conjunction with the accompanying drawings. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and all use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change of the proportional relationship or adjustment of the size, under the same or similar conditions as the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific environment to be applied and used. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or part with the same function, and its repeated description is omitted. In this specification, similar reference numerals and letters are used to refer to similar items, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures. In addition, if the method described herein includes a series of steps, the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0054] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements. The singular forms "a", "an" and "the" include plural objects, the term "or" is generally used in a sense including "and / or", the term "several" is generally used in a sense including "at least one", and the term "at least two" is generally used in a sense including "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and are not to be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features.

[0055] It should be understood that when an element is referred to as being "connected," "connected to," or "coupled to" another element, it can be directly connected to the other element, or there can be intervening elements. Conversely, when an element is referred to as being "directly connected" or "directly connected to" another element, there are no intervening elements.

[0056] In order to facilitate understanding and explanation of the present invention, before describing in detail the specific implementation methods of the DC bus capacitor discharge method, device, electronic device, and readable storage medium proposed in the present invention, the main research process of the present invention is briefly introduced as follows:

[0057] Specifically, see Figure 2 , Figure 2 Figure 1 is a schematic diagram of the bridge inverter direct discharge principle. Figure 2It can be seen that the basic principle of using the bridge arm direct discharge is: keep one of the power tubes in the upper and lower bridge arms (such as the second switch tube Q32 of the lower bridge of the bridge arm 130) in a normally on state, and give another power tube of the bridge arm (such as the first switch tube Q31 of the upper bridge) a PWM signal with a variable duty cycle, so that the upper and lower power tubes (such as the first switch tube Q31 and the second switch tube Q32) of the bridge arm (such as the bridge arm 130) switch between the direct on and off states, generating a pulsed current. Since the power tube of the upper bridge (such as the first switch tube Q31) is in the linear region during the switching process, a large switching loss will be generated, and the energy on the DC bus capacitor will be dissipated in the form of heat on the power tube (such as the first switch tube Q31 and the second switch tube Q32).

[0058] However, after in-depth research by the inventors, it was found that this discharge method has cost or application problems, which are roughly as follows: the higher the frequency of the PWM signal, the greater the duty cycle, the greater the energy dissipated on the power tube (such as the first switch tube Q31 and the second switch tube Q32) per unit time, and the faster the discharge speed of the high-voltage DC bus capacitor C. However, at the same time, the power tube is a device that is very sensitive to temperature. A large amount of heat accumulation in a short period of time may cause its junction temperature to be too high, eventually causing damage to the power tube. Therefore, when adopting a discharge solution for the DC bus capacitor C through a power tube, at least two requirements need to be taken into account: one is the discharge time, which must meet the system's requirements for the discharge time, and the other is the thermal safety of the power tube, which must ensure that the junction temperature of the power tube is in a safe range during the entire discharge process. Therefore, how to close-loop control the PWM signal pulse width of the upper bridge power tube under different environments and working conditions has become a problem that needs to be solved.

[0059] Based on the above research, the core idea of ​​the present invention is to provide a DC bus capacitor discharge method, device, electronic device and readable storage medium. The present invention can achieve basically constant power consumption of the power tube during the discharge process through more precise closed-loop control of the DC bus capacitor discharge pulse width, and effectively reduce the temperature rise of the power tube during the discharge process, thereby protecting the power tube and prolonging its life without increasing additional costs.

[0060] It should be noted that the DC bus capacitor discharge method and readable storage medium provided by the present invention can be applied to the discharge control device and electronic device for the DC bus capacitor provided by the present invention, and the DC bus capacitor discharge method, device, electronic device and readable storage medium provided by the present invention can be applied to vehicles. It should be understood that the terms "vehicle" or "vehicle" or other similar terms used herein include general motor vehicles, such as passenger vehicles including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles, etc.

[0061] Embodiment 1

[0062] In order to realize the above idea, this embodiment provides a DC bus capacitor discharge method. Figure 2 , Figure 3 , Figure 3 The overall flow chart of the DC bus capacitor discharge method provided in this embodiment is as follows. Figure 2 It can be seen that the DC bus capacitor C is connected in parallel with the input end of a bridge inverter 100, and the bridge inverter 100 includes at least one bridge arm ( Figure 2 ), each of the bridge arms includes a first switch tube and a second switch tube ( Figure 2 The middle bridge arm 110 includes a first switch tube Q11 and a second switch tube Q12, the bridge arm 120 includes a first switch tube Q21 and a second switch tube Q22, and the bridge arm 130 includes a first switch tube Q31 and a second switch tube Q32). For example, see Figure 3 ,from Figure 3 It can be seen that the DC bus capacitor C discharging method provided in this embodiment includes:

[0063] S100: Acquire a pulse width of a pulse width modulation signal of a first switch tube (such as the first switch tube Q31 ) of at least one of the bridge arms (such as the bridge arm 130 );

[0064] S200: During the discharge process of the DC bus capacitor C, the second switch tube (such as the second switch tube Q32) of the bridge arm (such as the bridge arm 130) is turned on, and the following steps are iteratively performed:

[0065] S211: determining a target discharge slope at a current sampling time according to a target discharge time and a target discharge voltage; the target discharge slope includes a voltage drop rate of the DC bus capacitor C;

[0066] S220: determining an actual discharge slope according to a voltage drop value of the DC bus capacitor C;

[0067] S230: updating the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope;

[0068] S240: Input the updated pulse width modulation signal to the first switch tube (such as the first switch tube Q31) on the bridge arm (such as the bridge arm 130) to discharge the DC bus capacitor C.

[0069] Therefore, the present invention provides the DC bus capacitor C discharge method. In the process of executing the DC bus capacitor C discharge, the target discharge slope at the current sampling moment is determined according to the target discharge time and the target discharge voltage; and the actual discharge slope is determined according to the voltage drop value of the DC bus capacitor C; and then the pulse width of the switch pulse width modulation signal is updated according to the target discharge slope and the actual discharge slope. Therefore, the present invention can realize more accurate closed-loop control of the discharge pulse width of the DC bus capacitor C, which can not only make the entire discharge process in a controllable state, so as to ensure that the discharge time meets the requirements, but also realize that the power consumption of the power tube in the discharge process is basically constant, thereby effectively reducing the temperature rise of the power tube in the discharge process, ensuring the thermal safety of the power tube, and better protecting the power tube to increase its life. Furthermore, the voltage drop value of the DC bus capacitor C can be obtained by reusing the existing voltage information acquisition method, thereby eliminating the need for an additional discharge current sampling circuit and increasing the additional cost, which can not only significantly reduce the cost, but also effectively reduce the area of ​​the control circuit, thereby improving the overall power density.

[0070] Preferably, in some embodiments, the pulse width of the pulse width modulation signal of the first switch tube of at least one of the bridge arms is obtained in step S100, and the pulse width of the switch pulse width modulation signal can be a pulse width preset value. At the start of discharge, the pulse width preset value is input to the first switch tube (such as the first switch tube Q31) of the bridge arm (such as the bridge arm 130) to discharge the DC bus capacitor C. Afterwards, the actual discharge slope and the target discharge slope are calculated starting from the second sampling moment, and the pulse width preset value is adjusted.

[0071] It should be noted that the present invention does not limit the specific value of the pulse width preset value. For example, in some embodiments, the pulse width preset value can be a non-zero value obtained based on experience or calibration; in other embodiments, the pulse width preset value can also be 0, and the pulse width preset value is determined based on the current voltage, current temperature, and the preset correspondence between bus voltage-switch tube temperature-drive pulse width. For the specific method of obtaining the pulse width preset value, please refer to the technology related to the discharge of the DC bus capacitor C known to those skilled in the art. Due to space limitations, this article will not elaborate on this.

[0072] It should be noted that, as those skilled in the art will appreciate, the present invention does not impose too many restrictions on the execution order of step S211 and step S220. For example, in some implementations, step S211 may be executed first to determine the target discharge slope at the current sampling moment, and then step S220 may be executed to determine the actual discharge slope; in other implementations, step S220 may be executed first to determine the actual discharge slope, and then step S211 may be executed to determine the target discharge slope at the current sampling moment; or in some other systems that support parallel computing, step S211 may be executed simultaneously to determine the target discharge slope at the current sampling moment and step S220 may be executed to determine the actual discharge slope. In addition, it should be particularly noted that those skilled in the art should be able to understand that, Figure 3 As shown, the above steps S211, S220, S230 and step S240 are iteratively executed until the discharge target of the DC bus capacitor C is completed.

[0073] In addition, the present invention does not impose too many restrictions on the bridge arm for implementing the discharge of the bus capacitor C. For example, in some exemplary embodiments, the bus capacitor C can be discharged only by controlling the first switch tube Q11 (or the second switch tube Q12) of the bridge arm 110. In other exemplary embodiments, the bus capacitor C can be discharged by controlling the first switch tube Q11 (or the second switch tube Q12) of the bridge arm 110 and the first switch tube Q21 (or the second switch tube Q22) of the bridge arm 120. In some other exemplary embodiments, the bus capacitor C can be discharged by controlling the first switch tube Q11 (or the second switch tube Q12) of the bridge arm 110, the first switch tube Q21 (or the second switch tube Q22) of the bridge arm 120, and the first switch tube Q31 (or the second switch tube Q32) of the bridge arm 130.

[0074] Preferably, in some exemplary embodiments, in step S211, determining the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage includes:

[0075] The target discharge slope at the current sampling moment is determined according to the target discharge time, the target discharge voltage, and the discharge duration of the discharge process.

[0076] Therefore, the present invention determines the target discharge slope at the current sampling moment according to the target discharge time, the target discharge voltage and the discharge duration of the discharge process, so as to make the discharge process controllable and ensure that the power consumption of the power tube during the discharge process is basically constant, thereby effectively reducing the temperature rise of the power tube during the discharge process and laying a reliable foundation.

[0077] Exemplarily, the target discharge slope at the current sampling moment is calculated by the following formula (1):

[0078]

[0079] In formula (1), U ′(t) is the target discharge slope at the current sampling moment, u0 is the target voltage (such as the initial bus voltage before discharge), t0 is the target discharge time (i.e., the required time to complete the discharge), and t is the discharge duration of the discharge process (i.e., the time elapsed during the discharge process).

[0080] Preferably, in some exemplary embodiments, the target discharge voltage is a pre-calibrated discharge voltage preset value. Thus, by using the pre-calibrated discharge voltage preset value as the target discharge voltage, the DC bus capacitor C discharge method provided by the present invention is easier to implement. It should be noted that the present invention does not impose too many restrictions on the specific value of the pre-calibrated discharge voltage preset value (i.e., the target discharge voltage). For example, the discharge voltage preset value may be 500V.

[0081] It should be noted that the present invention does not impose too many restrictions on the specific method of obtaining the pre-calibrated discharge voltage preset value. For example, in some embodiments, it can be obtained based on experience; in other embodiments, it can be obtained based on the average value of the highest bus voltage obtained by several vehicles with the same configuration during the vehicle calibration process.

[0082] Preferably, in some other exemplary embodiments, the target discharge voltage is the initial bus voltage before the discharge of the DC bus capacitor C. Thus, by using the initial bus voltage before discharge as the target discharge voltage, the discharge process of the DC bus capacitor C discharge method provided by the present invention can be controlled more accurately.

[0083] Preferably, in some further exemplary embodiments, the target discharge voltage is a difference between a preset initial voltage and a preset termination voltage.

[0084] Therefore, by using the difference between the preset initial voltage and the preset termination voltage as the target discharge voltage, the DC bus capacitor C discharge method provided by the present invention has wider applicability.

[0085] It should be noted that the present invention does not impose too many restrictions on the specific values ​​and acquisition methods of the preset initial voltage and the preset termination voltage. For example, in some exemplary embodiments, the preset initial voltage is the highest voltage of the bus, and the preset termination voltage is 0.

[0086] It should also be understood that the present invention does not impose too many restrictions on the method for obtaining the target discharge time. For example, in some exemplary embodiments, the target discharge time may be a preset value; in other embodiments, the target discharge time may also be dynamically configured according to actual needs.

[0087] Preferably, in some exemplary implementations, determining the actual discharge slope according to the voltage drop value of the DC bus capacitor C in step S220 includes:

[0088] S221: Calculate the voltage difference between the DC bus capacitor C at the current sampling moment and the previous sampling moment;

[0089] S222: Calculate the time difference between the current sampling time and the previous sampling time;

[0090] S223: Calculate the actual discharge slope according to the voltage difference and the time difference.

[0091] Therefore, the DC bus capacitor C discharging method provided by the present invention calculates the actual discharge slope according to the time difference between the current sampling moment and the previous sampling moment and the voltage difference between the DC bus capacitor C at the current sampling moment and the previous sampling moment, thereby laying a reliable foundation for updating the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope, so that the discharge process is in a controllable state, ensuring that the power consumption of the power tube during the discharge process is basically constant, thereby effectively reducing the temperature rise of the power tube during the discharge process, and can effectively improve the service life of the power tube.

[0092] It should be noted that the present invention does not impose too many restrictions on the duration between adjacent sampling moments (i.e., the time difference between the current sampling moment and the previous sampling moment). For example, in some embodiments, fixed periodic sampling can be performed, that is, the duration between any two adjacent sampling moments is the same. In other embodiments, the next sampling moment can also be dynamically determined based on the voltage value of the DC bus capacitor C at the current moment and the remaining discharge time, so as to further improve the control accuracy of the DC bus capacitor C discharge method provided by the present invention.

[0093] Preferably, in some exemplary embodiments, step S230 updates the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope, including:

[0094] S231: Calculate the difference between the absolute value of the actual discharge slope and the absolute value of the target discharge slope;

[0095] S232: If the difference is greater than a first preset threshold, reducing the pulse width of the switch pulse width modulation signal;

[0096] S233: If the difference is smaller than a second preset threshold, increasing the pulse width of the switch pulse width modulation signal.

[0097] Therefore, the active discharge method of the DC bus capacitor C provided by the present invention can reduce the dependence on the bus voltage sampling accuracy by using the energy difference between adjacent moments to perform dynamic control of the active discharge closed loop, and has good universality and good control accuracy.

[0098] It should be noted that the present invention does not impose too many restrictions on the values ​​of the first preset threshold and the second preset threshold, and the values ​​of the first preset threshold and the second preset threshold may be the same or different.

[0099] Preferably, in some exemplary embodiments, updating the pulse width of the switch pulse width modulation signal in step S240 includes: according to the difference, accumulating / subtracting according to a preset step length to update the pulse width of the switch pulse width modulation signal. Thus, the pulse width of the switch pulse width modulation signal is updated by accumulating or subtracting, which is simple in logic and easy to implement.

[0100] It should be understood that the present invention does not impose too many restrictions on the specific strategy of increasing or decreasing the pulse width of the switch pulse width modulation signal. For example, in some exemplary embodiments, no matter how large the deviation between the actual discharge slope and the target discharge slope is, as long as there is a deviation between the actual discharge slope and the target discharge slope, a preset value is increased or decreased based on the current pulse width; in other exemplary embodiments, the increase or decrease value of the pulse width can also be determined according to the deviation between the actual discharge slope and the target discharge slope.

[0101] Preferably, in some other exemplary embodiments, in step S240, updating the pulse width of the switch pulse width modulation signal includes: or using a PI control method to update the pulse width of the switch pulse width modulation signal. Thus, using the PI control method to update the pulse width of the switch pulse width modulation signal can utilize the advantages of the PI control method in terms of fast response and elimination of steady-state errors, and is more convenient for accurate control of discharge time and discharge power consumption.

[0102] For a better understanding of the present invention, see Figure 4 , Figure 4 The schematic diagram of the principle of the DC bus capacitor C discharge method provided in this embodiment, combined with Figure 4The basic principle of the active discharge method of the DC bus capacitor C provided in this embodiment is briefly described as follows:

[0103] like Figure 4 As shown, firstly, the target discharge slope at the current sampling moment (the specific calculation method can be found in the above formula (1)) and the actual discharge slope at the current sampling moment are determined, and then, according to the target discharge slope and the actual discharge slope, the pulse width of the switch pulse width modulation signal is updated (step addition / subtraction or PI control), and finally, the updated pulse width modulation signal is used to drive the corresponding power tube to switch between the on / off state to discharge the DC bus capacitor C.

[0104] Embodiment 2

[0105] This embodiment provides another method for discharging a DC bus capacitor C. The basic principle of the method for discharging a DC bus capacitor C provided in this embodiment is similar to that of the method for discharging a DC bus capacitor C provided in the first embodiment. In order to avoid redundant description, only the differences from the first embodiment are described below. For the parts not mentioned in this embodiment, please refer to the relevant description of the first embodiment for adaptive understanding. For example, please refer to Figure 5 , Figure 5 The schematic diagram of the principle of the DC bus capacitor C discharge method provided in this embodiment. Figure 5 and Figure 4 It can be found that the DC bus capacitor C discharging method provided in this embodiment is different from that in the first embodiment in that the target discharge slope at the current sampling moment in step S200 is obtained in a different manner, that is, step S212 of this embodiment corresponds to step S211 in the first embodiment.

[0106] Preferably, in some exemplary embodiments, the step S200 of determining the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage includes:

[0107] S212: Determine a target discharge slope at the current sampling moment according to the target discharge time, the target discharge voltage, and the current voltage value of the bus capacitor C at the current sampling moment.

[0108] Therefore, the present invention determines the target discharge slope at the current sampling moment according to the target discharge time, the target discharge voltage and the current voltage value of the bus capacitor C at the current sampling moment, so as to make the discharge process in a controllable state and ensure that the power consumption of the power tube during the discharge process is basically constant, thereby effectively reducing the temperature rise of the power tube during the discharge process. Lay a reliable foundation.

[0109] Exemplarily, the target discharge slope at the current sampling moment is calculated by the following formula (2):

[0110]

[0111] In formula (2), U' (U) is the target discharge slope at the current sampling moment, u0 is the target voltage (such as the initial bus voltage before discharge), t0 is the target discharge time (that is, the required time to complete the discharge, and U is the current voltage value at the current sampling moment during the discharge process (that is, the instantaneous value of the bus voltage collected at the current moment).

[0112] For a better understanding of the present invention, see Figure 5 , Figure 5 The schematic diagram of the principle of the DC bus capacitor C discharge method provided in this embodiment, combined with Figure 5 The basic principle of the active discharge method of the DC bus capacitor C provided in this embodiment is briefly described as follows:

[0113] like Figure 5 As shown, firstly, the target discharge slope at the current sampling moment (the specific calculation method can be found in the above formula (2)) and the actual discharge slope at the current sampling moment are determined, and then, according to the target discharge slope and the actual discharge slope, the pulse width of the switch pulse width modulation signal is updated (step addition / subtraction or PI control), and finally, the updated pulse width modulation signal is used to drive the corresponding power tube to switch between the on / off state to discharge the DC bus capacitor C.

[0114] Embodiment 3

[0115] This embodiment provides a discharge control device for a DC bus capacitor C. For example, see Figure 2 and Figure 6 ,in, Figure 6 A block diagram of the discharge control device for a DC bus capacitor provided in this embodiment. Figure 2 It can be seen that the DC bus capacitor C is connected in parallel with the input end of a bridge inverter 100, and the bridge inverter 100 includes at least one bridge arm ( Figure 2 ), each of the bridge arms includes a first switch tube and a second switch tube ( Figure 2 The bridge arm 110 includes a first switch tube Q11 and a second switch tube Q12, the bridge arm 120 includes a first switch tube Q21 and a second switch tube Q22, and the bridge arm 130 includes a first switch tube Q31 and a second switch tube Q32). Figure 6It can be seen that the discharge control device includes a discharge control unit 210, a target discharge slope acquisition unit 220, an actual discharge slope acquisition unit 230 and a pulse width adjustment unit 240. Specifically, the discharge control unit 210 is configured to acquire the pulse width of the pulse width modulation signal of the first switch tube (such as the first switch tube Q31) of at least one of the bridge arms (such as the bridge arm 130); and to turn on the second switch tube (such as the second switch tube Q32) of the bridge arm (such as the bridge arm 130). The target discharge slope acquisition unit 220 is configured to determine the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage; the target discharge slope includes the voltage drop rate of the DC bus capacitor C. The actual discharge slope acquisition unit 230 is configured to determine the actual discharge slope according to the voltage drop value of the DC bus capacitor C. The pulse width adjustment unit 240 is configured to update the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope. The discharge control unit 210 is further used to input the updated pulse width modulation signal to the first switch tube (Q11, Q21, Q31) on the bridge arm (110, 120, 130) to discharge the DC bus capacitor C.

[0116] Therefore, the discharge control device for the DC bus capacitor C provided by the present invention can realize more accurate closed-loop control of the discharge pulse width of the DC bus capacitor C, which can not only make the entire discharge process in a controllable state, thereby ensuring that the discharge time meets the requirements, but also realize that the power consumption of the power tube during the discharge process is basically constant, thereby effectively reducing the temperature rise of the power tube during the discharge process, ensuring the thermal safety of the power tube, and better protecting the power tube to increase its life. Further, the voltage drop value of the DC bus capacitor C can be obtained by reusing the existing voltage information acquisition method, thereby eliminating the need for an additional discharge current sampling circuit and increasing additional costs, which can not only significantly reduce costs, but also effectively reduce the area of ​​the control circuit, thereby improving the overall power density.

[0117] Since the discharge control device for the DC bus capacitor C provided in this embodiment has the same basic principle as the discharge method for the DC bus capacitor C provided in the present invention, in order to avoid redundancy, the discharge control device for the DC bus capacitor C provided in the present invention will not be described in detail here. For more detailed contents of the discharge control device for the DC bus capacitor C provided in the present invention, please refer to the above description of the discharge method for the DC bus capacitor C provided in the present invention for adaptive understanding.

[0118] Embodiment 4

[0119] This embodiment provides an electronic device. For example, see Figure 7 , Figure 7Schematic diagram of the block structure of the electronic device provided in this embodiment. Figure 7 As shown, the electronic device provided in this embodiment includes a processor 310 and a memory 320, and a computer program is stored in the memory 320. When the computer program is executed by the processor 310, the DC bus capacitor discharge method provided in any of the above embodiments is implemented. Since the electronic device provided in this embodiment and the DC bus capacitor discharge method provided in the present invention belong to the same inventive concept, the electronic device provided in this embodiment at least has all the advantages of the DC bus capacitor discharge method provided in the present invention. For details, please refer to the above description of the beneficial effects of the DC bus capacitor discharge method, which will not be repeated here.

[0120] For example, Figure 7 As shown, the electronic device may further include a communication interface 330 and a communication bus 340, wherein the processor 310, the communication interface 330, and the memory 320 communicate with each other via the communication bus 340. The communication bus 340 includes but is not limited to a CAN bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus. The communication interface 330 is used for the above-mentioned electronic device (such as a vehicle controller) and other controllers (such as a motor controller, an autonomous driving domain controller, a battery management system, etc., Figure 7 The communication bus 340 connects the above electronic devices (such as vehicle controller) with other controllers (such as battery management system, etc. Figure 7 The various scattered nodes (not shown) are connected into a closed-loop system, so that each controller of the vehicle can communicate and transmit data in multiple working states (parking state, charging state, starting state, running state, vehicle forward and reverse state, regenerative braking state, mechanical braking state, general fault state, major fault state), thereby realizing the control function of the vehicle.

[0121] The processor 310 referred to in the present invention may be a microcontroller unit (MCU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor 310 is the control center of the electronic device (such as a vehicle controller), and uses various interfaces and lines to connect various parts of the entire electronic device (such as a vehicle controller).

[0122] The memory 320 can be used to store the computer program, and the processor 310 implements various functions of the electronic device (such as the vehicle controller) by running or executing the computer program stored in the memory 320 and calling the data stored in the memory 320.

[0123] The memory 320 may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0124] Embodiment 5

[0125] This embodiment provides a readable storage medium, in which a computer program is stored, and when the computer program is executed by a processor, the DC bus capacitor discharge method described above can be implemented. Since the readable storage medium provided by the present invention and the DC bus capacitor discharge method provided by the present invention belong to the same inventive concept, the readable storage medium provided by the present invention at least has all the advantages of the DC bus capacitor discharge method provided by the present invention. For details of the beneficial effects of the readable storage medium provided by the present invention, please refer to the above description of the beneficial effects of the DC bus capacitor discharge method provided by the present invention, which will not be repeated here.

[0126] The readable storage medium of the embodiment of the present invention can adopt any combination of one or more computer-readable media. The readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared or semiconductor, or any combination of the above. More specific examples (non-exhaustive examples) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer hard disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this article, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, a device or a device or used in combination with it.

[0127] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0128] Computer program code for performing the operation of the present invention may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0129] Compared with the prior art, the present invention provides a DC bus capacitor discharge method, device, electronic device and readable storage medium, which have the following advantages: the DC bus capacitor discharge method provided by the present invention, in the process of executing the DC bus capacitor discharge, determines the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage; and determines the actual discharge slope according to the voltage drop value of the DC bus capacitor; and then updates the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope. As a result, the present invention can realize more accurate closed-loop control of the DC bus capacitor discharge pulse width, which can not only make the entire discharge process in a controllable state, so as to ensure that the discharge time meets the requirements, but also realize that the power consumption of the power tube in the discharge process is basically constant, thereby effectively reducing the temperature rise of the power tube in the discharge process, ensuring the thermal safety of the power tube, and better protecting the power tube to increase its life. Furthermore, the voltage drop value of the DC bus capacitor can be obtained by reusing the existing voltage information acquisition method, thereby eliminating the need for an additional discharge current sampling circuit and increasing the additional cost, which can not only significantly reduce the cost, but also effectively reduce the area of ​​the control circuit, thereby improving the overall power density.

[0130] It should be noted that the devices and methods disclosed in the embodiments of this article can also be implemented in other ways. The device implementation described above is only schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of this article. In this regard, each box in the flowchart or block diagram can represent a part of a module, program or code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented by a dedicated hardware-based system for performing a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0131] In addition, the functional modules in the various embodiments of this document may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0132] The above description is only a description of a preferred embodiment of a DC bus capacitor discharge method, device, electronic device and readable storage medium provided by the present invention, and is not any limitation on the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure content belong to the protection scope of the present invention. Obviously, technicians in this field can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. In this way, if these modifications and variations fall within the scope of the present invention and its equivalent technology, the present invention is also intended to include these changes and variations.

Claims

1. A method for discharging a DC bus capacitor, wherein the DC bus capacitor is connected in parallel to an input end of a bridge inverter, wherein the bridge inverter comprises at least one bridge arm, and each bridge arm comprises a first switch tube and a second switch tube; characterized in that: The DC bus capacitor discharge method comprises: Acquire a pulse width of a pulse width modulation signal of a first switch tube of at least one of the bridge arms; During the DC bus capacitor discharge process, the second switch tube of the bridge arm is turned on, and the following steps are iteratively performed: Determine the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage; the target discharge slope includes the voltage drop rate of the DC bus capacitor; Determining an actual discharge slope according to a voltage drop value of the DC bus capacitor; updating the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope; The updated pulse width modulation signal is input to the first switch tube on the bridge arm to discharge the DC bus capacitor.

2. The DC bus capacitor discharge method according to claim 1, characterized in that: Determining the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage includes: The target discharge slope at the current sampling moment is determined according to the target discharge time, the target discharge voltage, and the discharge duration of the discharge process.

3. The DC bus capacitor discharge method according to claim 2, characterized in that: The target discharge voltage includes a pre-calibrated discharge voltage preset value or an initial bus voltage before the DC bus capacitor is discharged.

4. The DC bus capacitor discharge method according to claim 2, characterized in that: Determining the actual discharge slope according to the voltage drop value of the DC bus capacitor includes: Calculating the voltage difference between the DC bus capacitor at the current sampling moment and the previous sampling moment; Calculating the time difference between the current sampling moment and the previous sampling moment; The actual discharge slope is calculated according to the voltage difference and the time difference.

5. The DC bus capacitor discharge method according to claim 1, characterized in that: The updating of the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope comprises: Calculating a difference between the absolute value of the actual discharge slope and the absolute value of the target discharge slope; If the difference is greater than a first preset threshold, reducing the pulse width of the switch pulse width modulation signal; If the difference is smaller than a second preset threshold, the pulse width of the switch pulse width modulation signal is increased.

6. The DC bus capacitor discharge method according to claim 5, characterized in that: The updating of the pulse width of the switch pulse width modulation signal comprises: According to the difference, the pulse width of the switch pulse width modulation signal is updated by accumulating / subtracting according to a preset step size or by adopting a PI control method.

7. The DC bus capacitor discharge method according to claim 2, characterized in that: Determining the target discharge slope at the current sampling moment according to the target discharge time and the target discharge voltage includes: The target discharge slope at the current sampling moment is determined according to the target discharge time, the target discharge voltage, and the current voltage value of the bus capacitor at the current sampling moment.

8. A discharge control device for a DC bus capacitor, wherein the DC bus capacitor is connected in parallel to an input end of a bridge inverter, wherein the bridge inverter comprises at least one bridge arm, and each bridge arm comprises a first switch tube and a second switch tube; characterized in that: The discharge control device comprises: A discharge control unit, configured to obtain a pulse width of a pulse width modulation signal of a first switch tube of at least one of the bridge arms; and to turn on a second switch tube of the bridge arm during the discharge of the DC bus capacitor; A target discharge slope acquisition unit is configured to determine a target discharge slope at a current sampling moment according to a target discharge time and a target discharge voltage; the target discharge slope includes a voltage drop rate of the DC bus capacitor; An actual discharge slope acquisition unit is configured to determine an actual discharge slope according to a voltage drop value of the DC bus capacitor; a pulse width adjustment unit, configured to update the pulse width of the switch pulse width modulation signal according to the target discharge slope and the actual discharge slope; The discharge control unit is further used to input the updated pulse width modulation signal to the first switch tube on the bridge arm to discharge the DC bus capacitor.

9. An electronic device, characterized in that: The method comprises a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the DC bus capacitor discharge method according to any one of claims 1 to 7 is implemented.

10. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and when the computer program is executed by a processor, the DC bus capacitor discharge method according to any one of claims 1 to 7 is implemented.

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