Method, apparatus, storage medium and system for charging a bootstrap capacitor of a motor

Abstract

The application provides a method, device, storage medium and system for charging a bootstrap capacitor of a motor, the method comprising: receiving and responding to an instruction for powering on the motor, controlling a first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously controlling a second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, to charge the bootstrap capacitor in each phase bridge arm circuit, wherein each phase bridge arm circuit comprises a bootstrap capacitor, the bridge arm circuits are electrically connected to U-phase, V-phase and W-phase windings of the motor to drive the motor, the first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals, and the complementary pulse width modulation signals represent that only one of the first bridge arm and the second bridge arm of each phase bridge arm circuit is allowed to be turned on at any time period. The application solves the problem of unstable charging voltage in the initial stage of powering on the motor in the prior art, which leads to abnormal motor driving.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control and power electronics, in particular to a method for charging a bootstrap capacitor of a motor, a device for charging a bootstrap capacitor of a motor, a computer readable storage medium and a system for charging a bootstrap capacitor of a motor. BACKGROUND

[0002] In the operation process of a permanent magnet synchronous motor, a stable DC power supply is usually needed to support the work of the inverter and other electronic components. The bootstrap capacitor charging is significant to provide the necessary voltage for the IGBT or insulated gate bipolar transistor drive circuit of the upper bridge arm, and to ensure its normal work. In a three-phase inverter, each bridge arm is composed of two IGBTs or insulated gate bipolar transistors: an upper bridge arm connected to the positive bus and a lower bridge arm connected to the negative bus. Since there is no direct voltage source between the emitter of the upper bridge arm IGBT and the positive bus, the drive circuit of the upper bridge arm needs to be powered through a bootstrap circuit. When the motor starts, the bootstrap capacitor needs to be charged so that it stores enough energy to ensure that the upper bridge arm IGBT can be turned on and off correctly.

[0003] The traditional bootstrap capacitor charging method is usually that three bridge arms are charged at the same constant duty ratio, and the upper and lower bridge arm IGBTs are charged to the bootstrap capacitor in complementary pulse width. Because the capacitor has no electricity before charging, if a large duty ratio is used for charging, the driving power supply voltage may be instantaneously lowered or the charging current may be too large to trigger the motor overcurrent protection. If a small duty ratio is used for charging, the charging time may be too long, which affects the timeliness of the motor start. SUMMARY

[0004] The main purpose of the present application is to provide a method for charging a bootstrap capacitor of a motor, a device for charging a bootstrap capacitor of a motor, a computer readable storage medium and a system for charging a bootstrap capacitor of a motor, to at least solve the problem of unstable charging voltage in the initial stage of the motor power-on in the prior art, which leads to abnormal motor drive.

[0005] To achieve the above object, according to one aspect of the present application, a method for charging bootstrap capacitors of a motor is provided, comprising: receiving and responding to an instruction of power-on of the motor, controlling a first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously controlling a second bridge arm of the bridge arm circuit of each phase according to a preset second pulse width modulation signal, to achieve charging of a bootstrap capacitor in the bridge arm circuit of each phase, wherein the bridge arm circuit of each phase comprises one bootstrap capacitor, the bridge arm circuit is respectively electrically connected with a U-phase, V-phase and W-phase winding of the motor to drive the motor, the first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals, and the complementary pulse width modulation signals represent that only one of the first bridge arm and the second bridge arm in the bridge arm circuit of each phase is allowed to conduct at any time period.

[0006] Optionally, the controlling of the first bridge arm of each phase bridge arm circuit according to the preset first pulse width modulation signal, and the controlling of the second bridge arm of the bridge arm circuit of each phase according to the preset second pulse width modulation signal, comprises: adjusting a pulse width of the first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width according to a first preset function, and adjusting the pulse width of the second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width according to a second preset function, the first preset initial pulse width is greater than the second preset initial pulse width, the first preset target pulse width is less than the second preset target pulse width, the first preset function is a monotonically decreasing function, and the second preset function is a monotonically increasing function.

[0007] Optionally, after the adjusting of the pulse width of the second pulse width modulation signal from the second preset initial pulse width to the second preset target pulse width, the method further comprises: driving the second bridge arm in the bridge arm circuit of each phase according to the second preset target pulse width to charge the bootstrap capacitor until a voltage of the bootstrap capacitor reaches a preset threshold.

[0008] Optionally, after the charging of the bootstrap capacitor until the voltage of the bootstrap capacitor reaches the preset threshold, the method further comprises: monitoring the voltage of the bootstrap capacitor of each phase bridge arm circuit in real time, and charging the bootstrap capacitor with the voltage less than the preset threshold according to a preset third pulse width modulation signal in the case that the voltage of any bootstrap capacitor is less than the preset threshold, the third pulse width modulation signal being a constant duty cycle modulation signal.

[0009] Optionally, a falling edge of the first pulse width modulation signal and a rising edge of the second pulse width modulation signal have a preset first time interval, the falling edge of the second pulse width modulation signal and the rising edge of the first pulse width modulation signal have a preset second time interval, and the first time interval is equal to the second time interval.

[0010] Optionally, before controlling the first bridge arm of each phase bridge arm circuit according to the preset first pulse width modulation signal and controlling the second bridge arm of each phase bridge arm circuit according to the preset second pulse width modulation signal, the method further comprises: pre-charging each bootstrap capacitor by using a direct current power supply, so that the voltage of each bootstrap capacitor reaches a preset initial voltage value.

[0011] Optionally, the method further comprises: monitoring the temperature of each bootstrap capacitor in real time, and in the case that the temperature of any bootstrap capacitor is greater than a preset temperature threshold, suspending the charging of each bootstrap capacitor until the temperature of the bootstrap capacitor is less than or equal to the preset temperature threshold.

[0012] According to another aspect of the present application, there is provided a device for charging bootstrap capacitors of an electric machine, comprising: a control unit configured to receive and respond to an instruction of power-on of an electric machine, control a first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal and control a second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal to charge a bootstrap capacitor in each phase bridge arm circuit, wherein each phase bridge arm circuit comprises one bootstrap capacitor, and each phase bridge arm circuit is electrically connected to a U-phase, V-phase and W-phase winding of the electric machine to drive the electric machine, the first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals, and the complementary pulse width modulation signals represent that only one of the first bridge arm and the second bridge arm in each phase bridge arm circuit is allowed to be turned on at any time period.

[0013] According to still another aspect of the present application, there is provided a computer readable storage medium, comprising a stored program, wherein the computer readable storage medium is configured to perform any of the methods described above when the program is executed.

[0014] According to yet another aspect of the present application, there is provided a system for charging bootstrap capacitors of an electric machine, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs comprise instructions for performing any of the methods described above.

[0015] According to the technical scheme, the first bridge arm of each phase bridge arm circuit is controlled according to a preset first pulse width modulation signal, and the second bridge arm of each phase bridge arm circuit is controlled according to a preset second pulse width modulation signal to charge the bootstrap capacitor in each phase bridge arm circuit in response to the instruction of powering on the motor. The technical scheme controls the conduction states of the first bridge arm and the second bridge arm of the three-phase bridge arm circuit at the same time when the motor is powered on, realizes parallel charging of the bootstrap capacitor in each phase bridge arm circuit, keeps the voltage of the bootstrap capacitor stable during the charging process, and avoids the excessive subsequent charging current caused by the rapid decline of the capacitor voltage in the charging mode of charging the capacitor of each phase bridge arm circuit respectively in the prior art, and solves the problem of unstable charging voltage in the initial stage of powering on the motor in the prior art, which leads to abnormal motor driving. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which form a part of the present description, illustrate the present application and together with the written description serve to explain the application. In the drawings:

[0017] Figure 1 A flowchart of a method for charging a bootstrap capacitor of a motor is shown according to an embodiment of the present application;

[0018] Figure 2 A schematic diagram of a pulse width modulation signal is shown according to an embodiment of the present application;

[0019] Figure 3 A structural block diagram of a device for charging a bootstrap capacitor of a motor is shown according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] It should be noted that the embodiments and features in the present application can be combined with each other without conflict. The technical scheme of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] In order to enable those skilled in the art to better understand the present application, the technical scheme of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0022] It should be noted that the terms "first", "second" and the like in the description and in the claims of the present application and the above-mentioned accompanying drawings are intended to distinguish similar objects and are not necessarily used to describe a particular sequential or chronological order. It should be understood that the data thus used can be interchanged, where appropriate, to describe the embodiments of the present application described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or apparatus that includes a list of steps or units is not necessarily limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to such processes, methods, products or apparatus.

[0023] As introduced in the background, the charging voltage is unstable in the initial stage of the motor power-on in the prior art, resulting in abnormal motor driving. To solve the above technical problems, embodiments of the present application provide a method for charging bootstrap capacitor of motor, a device for charging bootstrap capacitor of motor, a computer readable storage medium and a system for charging bootstrap capacitor of motor.

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.

[0025] Figure 1 is a flowchart of the method for charging bootstrap capacitor of motor according to the embodiments of the present application. As shown in Figure 1 , the method comprises the following steps:

[0026] Step S101, in response to the instruction of the motor power-on, a first bridge arm of each phase bridge arm circuit is controlled according to a preset first pulse width modulation signal, and a second bridge arm of each phase bridge arm circuit is controlled according to a preset second pulse width modulation signal at the same time, so as to charge the bootstrap capacitor in each phase bridge arm circuit,

[0027] wherein each phase bridge arm circuit comprises a bootstrap capacitor, the bridge arm circuit is electrically connected with U-phase, V-phase and W-phase windings of the motor respectively to drive the motor, the first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals, and the complementary pulse width modulation signals represent that only one bridge arm of the first bridge arm and the second bridge arm in each phase bridge arm circuit is allowed to be turned on at any time period.

[0028] Specifically, the U-phase, V-phase and W-phase of the motor each have a group of bridge arm circuits comprising a first bridge arm and a second bridge arm, and the first bridge arm and the second bridge arm are each configured with a controllable switching device, and each phase bridge arm circuit comprises a bootstrap capacitor. In the case that the first bridge arm is turned off and the second bridge arm is turned on, the bootstrap capacitor is charged, and in the case that the first bridge arm is turned on and the second bridge arm is turned off, the bootstrap capacitor is isolated from the charging circuit.

[0029] Through the above-mentioned embodiments, by receiving and responding to the instruction of the motor power-on, the first bridge arm of each phase bridge arm circuit is controlled according to the preset first pulse width modulation signal, and the second bridge arm of each phase bridge arm circuit is controlled according to the preset second pulse width modulation signal at the same time, so as to realize the charging of the bootstrap capacitor in each phase bridge arm circuit. The scheme realizes the parallel charging of the bootstrap capacitor in each phase bridge arm circuit by simultaneously controlling the conduction states of the first bridge arm and the second bridge arm of the three-phase bridge arm circuit when the motor is powered on, so that the voltage of the bootstrap capacitor remains stable during the charging process. The problem of excessive subsequent charging current caused by rapid decline of the capacitor voltage in the prior art charging mode of charging the capacitor of each phase bridge arm circuit respectively is avoided, and the problem of unstable charging voltage at the initial stage of motor power-on in the prior art, which leads to abnormal motor driving, is solved.

[0030] In an optional solution, the first bridge arm of each phase bridge arm circuit is controlled according to the preset first pulse width modulation signal, and the second bridge arm of each phase bridge arm circuit is controlled according to the preset second pulse width modulation signal, including: adjusting the pulse width of the first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width according to a first preset function; adjusting the pulse width of the second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width according to a second preset function, the first preset initial pulse width is greater than the second preset initial pulse width, the first preset target pulse width is less than the second preset target pulse width, the first preset function is a monotonically decreasing function, and the second preset function is a monotonically increasing function.

[0031] In the above embodiment, by using the first preset function to gradually control the conduction pulse width of the first bridge arm in a monotonically decreasing manner, and using the second preset function to gradually control the conduction pulse width of the second bridge arm in a monotonically increasing manner, the conduction window of the bootstrap capacitor is gradually lengthened, and the charging opportunity is more intensive, so that the voltage of the bootstrap capacitor rises smoothly, avoiding the voltage fluctuation and incomplete charging caused by time-sharing charging in the prior art. At the same time, the change of the pulse width follows the preset function, effectively suppressing the instantaneous large current impact caused by the sudden increase of the duty cycle, reducing the risk of triggering the overcurrent protection, and protecting the safety of the power device. Further, the conduction duty cycle of the first bridge arm gradually decreases, i.e. the conduction time of the first bridge arm shortens, which means that the total conduction loss of the first bridge arm will decrease, and the total conduction loss includes the loss on the conduction resistance and the switching loss. The conduction duty cycle of the second bridge arm gradually increases, i.e. the conduction time of the second bridge arm becomes longer, which provides more opportunities for the bootstrap capacitor to charge, so that the charging speed is faster and the charging is more complete. Therefore, while the charging speed is fast enough, the bridge arm device will not be subjected to large current conduction for a long time, avoiding excessive conduction loss, so that the overall efficiency of the entire system is higher, both fast charging and reducing heat and power waste, and the conduction time of the two bridge arms is optimally allocated under the premise of ensuring the charging speed, so that the charging and loss are balanced.

[0032] Specifically, the first preset initial pulse width and the second preset initial pulse width are determined according to the bootstrap capacitor capacity, the bus voltage and the safe working area of the switching device. The rising curve of the bootstrap voltage under different duty cycles can be tested by simulation or oscilloscope, and the duty cycle that can raise the capacitor voltage to 70% to 85% of the required driving voltage within 1 to 3 pulse width modulation periods is selected as the initial pulse width. For example, if the pulse width modulation period is 20 µs, the initial pulse width can be selected as 10 to 12 µs.

[0033] In another optional solution, after adjusting the pulse width of the second pulse width modulation signal from the second preset initial pulse width to the second preset target pulse width, the method further comprises: driving the second bridge arm in each phase of the bridge arm circuit according to the second preset target pulse width to charge the bootstrap capacitor until the voltage of the bootstrap capacitor reaches a preset threshold.

[0034] In the above embodiment, after the second pulse width modulation signal reaches the second preset target pulse width, each phase self-boosting capacitor is continuously charged at the second preset target pulse width until the capacitor voltage reaches the preset threshold, thereby forming a stable and predictable charging phase. Through the above method, each phase is charged in parallel under the same strategy, so that the self-boosting capacitor voltage of each phase rises uniformly, reduces the voltage deviation between phases, improves the symmetry of three-phase drive, and improves the success rate and stability of motor starting. At the same time, charging with the target duty ratio and stopping in time after reaching the threshold can suppress overcharging and energy waste, reduce the thermal load of the device, achieve a dynamic balance between the charging rate and the power device loss, while ensuring the rapid establishment of the self-boosting voltage, reduce the thermal stress and energy waste of the device, and make the overall operation efficiency of the system reach the best state.

[0035] In some example embodiments, after charging the above self-boosting capacitor until the voltage of the above self-boosting capacitor reaches the preset threshold, the above method further comprises: monitoring the voltage of the above self-boosting capacitor of the above bridge arm circuit of each phase in real time, and in the case that the voltage of any of the above self-boosting capacitors is less than the above preset threshold, charging the above self-boosting capacitor with the voltage less than the above preset threshold according to a preset third pulse width modulation signal, the above third pulse width modulation signal being a constant duty ratio modulation signal.

[0036] In the above embodiment, by monitoring the voltage state of the self-boosting capacitor of each phase bridge arm circuit in real time, and immediately supplementing power based on the third pulse width modulation signal with constant duty ratio when the voltage is lower than the preset threshold, the continuous and stable supply of the first bridge arm drive voltage is realized, preventing power device failure or motor operation abnormality caused by insufficient drive voltage. The power supplement strategy of the present scheme responds quickly and can restore the self-boosting capacitor voltage to the normal range in a very short time, and the constant duty ratio signal helps to reduce the charging current impact and electromagnetic interference, and reduce the bus and phase point voltage ripple. At the same time, it avoids frequent deep discharge of the self-boosting capacitor, reduces the thermal stress of the power device and the driver, and prolongs the service life. Through the above method, the continuity of three-phase drive output is ensured, and the reliability and stability of the equipment under long-time operation are ensured.

[0037] Specifically, when driving the first bridge arm, the gate voltage of the driving chip of the first bridge arm must be higher than the source voltage by at least a specified minimum voltage value to ensure that the power switch device can be reliably turned on, and the above minimum value is between 10V and 12V, depending on the device type and specification. Once the voltage provided by the self-boosting capacitor is lower than this value, the driving chip of the first bridge arm may not be fully turned on or may have slow switching speed, waveform distortion, or even be unable to turn on, resulting in motor starting failure or jitter. Therefore, the preset threshold is the minimum self-boosting voltage value to ensure the normal operation of the high-side drive.

[0038] In some example embodiments, the first time interval is equal to the second time interval.

[0039] In some example embodiments, the first time interval is equal to the second time interval.

[0040] In some example embodiments, the first time interval is equal to the second time interval.

[0041] In some example embodiments, the first time interval is equal to the second time interval.

[0042] In the above embodiments, before entering the normal charging control based on the first and second pulse width modulation signals, the respective bootstrap capacitors are pre-charged by the direct current power supply, so that the respective bootstrap capacitors have a certain initial voltage reserve in advance, thereby ensuring that the high-side drive circuit can immediately obtain a stable drive voltage at the initial power-up stage, avoiding the situation that the high-side power device cannot be turned on in time or is unstable due to the excessively low initial voltage of the bootstrap capacitor. Therefore, the bootstrap voltage establishment time in the starting stage is shortened, the response speed of the motor starting is improved, in addition, the peak value of the impact current on the bus at the initial charging moment is also reduced, thereby reducing the stress of the power device and the drive chip, and prolonging the service life of the device.

[0043] In an optional solution, the temperature of each bootstrap capacitor is monitored in real time, and in the case that the temperature of any bootstrap capacitor is greater than a preset temperature threshold, the charging of each bootstrap capacitor is suspended until the temperature of the bootstrap capacitor is less than or equal to the preset temperature threshold, and then the charging of each bootstrap capacitor is resumed.

[0044] In the above embodiments, by monitoring the temperature of each bootstrap capacitor in real time, the charging process can be suspended in time when the temperature exceeds the preset safety threshold, thereby effectively preventing problems such as performance degradation, dielectric breakdown or failure caused by overheating of the capacitor. During the suspension of charging, the capacitor can be naturally cooled or cooled by a cooling system, avoiding the accelerated wear of the capacitor life caused by continuous high temperature. When the temperature returns to the safety range, the charging is automatically resumed. Not only the safety of the drive circuit is improved, but also the increase of the leakage current and the energy loss caused by high temperature are reduced, thereby ensuring the continuity and consistency of the motor control.

[0045] Embodiments of the present application provide a specific implementation scenario of motor bootstrap capacitor charging. In the present embodiment, each phase bridge arm circuit is composed of a first bridge arm and a second bridge arm, and is provided with a corresponding bootstrap capacitor. Figure 2The first state is that when the pulse width control signal of the first bridge arm is high level and the pulse width control signal of the second bridge arm is low level, the first bridge arm is turned on and the second bridge arm is turned off. At this time, the bootstrap capacitors of the U phase, the V phase and the W phase are all isolated from the circuit and are in the uncharged state. The second state is that when the pulse width control signal of the first bridge arm is low level and the pulse width control signal of the second bridge arm is high level, the first bridge arm is turned off and the second bridge arm is turned on. At this time, the bootstrap capacitors of the U phase, the V phase and the W phase all start to charge, and the charging time is determined by the pulse width of the pulse width modulation signal of the second bridge arm. During the charging process, the pulse width of the pulse width modulation signal of the second bridge arm gradually increases from small to large, and the pulse width of the pulse width modulation signal of the first bridge arm gradually decreases from large to small, and the pulse width variation Δt=t2-t1 of the two is the increase of the turn-on time of the second bridge arm or the decrease of the turn-on time of the first bridge arm, which is set according to the bus power capacity and the required charging speed, and the adjustment amplitude is set between 5% to 10% of the total duty cycle. In order to avoid the simultaneous conduction of the upper and lower tubes on the same bridge arm, a dead time is inserted between the turn-off of the first bridge arm to the turn-on of the second bridge arm and between the turn-off of the second bridge arm to the turn-on of the first bridge arm, that is, the rising edge and the falling edge of the pulse width of un, vn and wn are separated from the falling edge and the rising edge of the pulse width of up, vp and wp by Δt1 and Δt2, which is determined by the switching characteristics of the power device and is usually 1-4 μs. When the pulse width of the pulse width modulation signal of the second bridge arm increases to the preset maximum value, the duty cycle is kept until the bootstrap capacitor is full, and the whole constant pulse width charging phase t3 is usually completed within 100 ms.

[0046] The embodiment of the application also provides a specific implementation scenario that an initial pulse width of a pulse width modulation signal gradually changes into a target pulse width according to a monotonic function, in which the motor driving system is a three-phase inverter bridge structure, each phase bridge arm circuit includes an upper bridge arm power device, i.e., a first bridge arm, a lower bridge arm power device, i.e., a second bridge arm, and a bootstrap capacitor associated with the upper bridge arm driving circuit. The three phases correspond to U-phase, V-phase and W-phase windings of the motor respectively. After the system is powered on, the controller receives a motor power-on instruction and starts a bootstrap capacitor charging process: in the initial charging stage, the first pulse width modulation signal for controlling the first bridge arm has a duty cycle set as a high value, such as 60%, so that the high-side drive establishes sufficient bootstrap voltage in a short time; as the charging process proceeds, the duty cycle gradually decreases to a target value, such as 20%, according to a preset first monotonic decreasing function, so as to reduce the conduction loss and device stress; the function shape and start-stop value can be pre-calibrated according to the bootstrap capacitor capacity, bus voltage and safe working area of the power device. In the initial charging stage, the second pulse width modulation signal for controlling the second bridge arm has a duty cycle set as a low value, such as 20%, so as to avoid a too large charging current impact at the beginning of charging; the duty cycle gradually increases to a target value, such as 60%, according to a preset second monotonic increasing function, so as to gradually lengthen the low-side conduction time, increase the charging opportunity and make the charging more uniform; the function curve can also be optimized through simulation or oscilloscope measurement, so as to balance the charging speed and device loss. The above first and second pulse width modulation signals are complementary waveforms, and only one of the first bridge arm or the second bridge arm is allowed to conduct at any time period; when the signals are alternately conducted, symmetric first and second dead time is inserted, so as to prevent shoot-through short circuit and reduce the instantaneous high voltage stress borne by the bootstrap capacitor during bridge arm switching. Through the above scheme, the gradual lengthening of the low-side conduction time makes the charging process of the bootstrap capacitor present a slow-rising curve, avoiding the obvious fluctuation of the bootstrap voltage caused by time-sharing charging; the charging process is more continuous and stable, the voltage fluctuation obtained by the high-side drive is small, and the driving signal is more reliable. In addition, the duty cycle gradually changes according to the function, avoiding the capacitor charging current impact caused by the instantaneous large duty cycle, reducing the probability of false triggering of the overcurrent protection of the driving chip or the controller; at the same time, the power device is protected from the instantaneous large current stress, the device life is prolonged, and the safety of the circuit is improved.

[0047] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that here.

[0048] The embodiment of the present application further provides a device for charging a bootstrap capacitor of a motor. It should be noted that the device for charging a bootstrap capacitor of a motor in the embodiment of the present application can be used to execute the method for charging a bootstrap capacitor of a motor provided by the embodiment of the present application. The device is used to realize the above-mentioned embodiment and preferred embodiment, and the description has been made above. As used below, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the device described in the following embodiment is preferably realized in software, the realization of hardware or a combination of software and hardware is also possible and conceived.

[0049] The device for charging a bootstrap capacitor of a motor provided by the embodiment of the present application is introduced below.

[0050] Figure 3 is a schematic diagram of the device for charging a bootstrap capacitor of a motor according to the embodiment of the present application. As shown in Figure 3 , the device comprises:

[0051] a control unit 10 configured to receive and respond to an instruction of powering on a motor, control a first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously control a second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, so as to charge a bootstrap capacitor in each phase bridge arm circuit,

[0052] wherein each phase bridge arm circuit comprises one bootstrap capacitor, the bridge arm circuit is electrically connected to a U-phase winding, a V-phase winding and a W-phase winding of the motor to drive the motor, the first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals, and the complementary pulse width modulation signals represent that only one bridge arm of the first bridge arm and the second bridge arm in each phase bridge arm circuit is allowed to be turned on at any time period.

[0053] Specifically, the U-phase, the V-phase and the W-phase of the motor each have a group of bridge arm circuits comprising a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm are each configured with a controllable switching device, and each phase bridge arm circuit comprises one bootstrap capacitor. In the case that the first bridge arm is turned off and the second bridge arm is turned on, the bootstrap capacitor is charged, and in the case that the first bridge arm is turned on and the second bridge arm is turned off, the bootstrap capacitor is isolated from a charging circuit.

[0054] According to the above embodiment, the control unit receives and responds to the instruction of the motor power-on, controls the first bridge arm of each phase bridge arm circuit according to the preset first pulse width modulation signal, and controls the second bridge arm of each phase bridge arm circuit according to the preset second pulse width modulation signal at the same time, to realize the charging of the bootstrap capacitor in each phase bridge arm circuit. The scheme controls the conduction states of the first bridge arm and the second bridge arm of the three-phase bridge arm circuit at the same time when the motor is powered on, realizes the parallel charging of the bootstrap capacitor in each phase bridge arm circuit, keeps the voltage of the bootstrap capacitor stable during the charging process, and avoids the excessive charging current caused by the rapid decline of the capacitor voltage in the charging mode of charging the capacitor of each phase bridge arm circuit respectively in the prior art, solves the problem of unstable charging voltage in the initial stage of the motor power-on in the prior art, and causes the motor drive to be abnormal.

[0055] As an optional solution, the control unit comprises: a first adjusting module, configured to adjust the pulse width of the first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width according to a first preset function; and a second adjusting module, configured to adjust the pulse width of the second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width according to a second preset function, the first preset initial pulse width is greater than the second preset initial pulse width, the first preset target pulse width is less than the second preset target pulse width, the first preset function is a monotonically decreasing function, and the second preset function is a monotonically increasing function.

[0056] In the above embodiment, the conduction pulse width of the first bridge arm is gradually controlled by the monotonically decreasing first preset function, and the conduction pulse width of the second bridge arm is gradually controlled by the monotonically increasing second preset function, so that the conduction window of the bootstrap capacitor is gradually lengthened, the charging opportunity is more intensive, the voltage of the bootstrap capacitor is smoothly increased, and the voltage fluctuation and the problem of not being fully charged caused by the time-sharing charging in the prior art are avoided. At the same time, the change of the pulse width follows the preset function, effectively inhibits the instantaneous large current impact caused by the sudden increase of the duty cycle, reduces the risk of triggering the overcurrent protection, and protects the safety of the power device. Further, the first bridge arm conduction duty cycle gradually decreases, that is, the first bridge arm conduction time is shortened, which means that the total conduction loss of the first bridge arm will be reduced, and the total conduction loss includes the loss on the conduction resistance and the switching loss. The second bridge arm conduction duty cycle gradually increases, that is, the conduction time of the second bridge arm is lengthened, which provides more charging opportunities for the bootstrap capacitor, speeds up the charging, and makes the charging more sufficient. Therefore, while the charging speed is fast enough, the bridge arm device will not bear large current conduction for a long time, avoiding high conduction loss, so that the overall efficiency of the whole system is higher, the charging is full and the power waste is reduced, and the conduction time of the two bridge arms is optimally allocated under the premise of ensuring the charging speed, so that the charging and loss are balanced.

[0057] Specifically, the first preset initial pulse width and the second preset initial pulse width are determined according to the bootstrap capacitor capacity, the bus voltage, and the safe operating area of the switching device. The rising curve of the bootstrap voltage under different duty cycles can be tested by simulation or oscilloscope, and the duty cycle that can raise the capacitor voltage to 70% to 85% of the required driving voltage within 1 to 3 pulse width modulation periods is selected as the initial pulse width. For example, if the pulse width modulation period is 20 µs, the initial pulse width can be selected as 10 to 12 µs.

[0058] In an alternative solution, the control unit further comprises a driving module configured to drive the second bridge arm in each phase bridge arm circuit according to the second preset target pulse width to charge the bootstrap capacitor until the voltage of the bootstrap capacitor reaches a preset threshold.

[0059] In the above embodiment, after the second pulse width modulation signal reaches the second preset target pulse width, the bootstrap capacitor of each phase is continuously charged at the second preset target pulse width until the capacitor voltage reaches the preset threshold, thereby forming a stable and predictable charging phase. By the above method, each phase is charged in parallel under the same strategy, so that the bootstrap capacitor voltage of each phase is lifted consistently, the voltage deviation between phases is reduced, the symmetry of three-phase drive is improved, and the success rate and stability of motor starting are improved. At the same time, charging at the target duty cycle and stopping in time after reaching the threshold can suppress overcharging and energy waste, reduce the thermal load of the device, achieve a dynamic balance between the charging rate and the power device loss, ensure the rapid establishment of the bootstrap voltage, reduce the thermal stress of the device and energy waste, and make the overall operation efficiency of the system reach the best state.

[0060] In some exemplary embodiments, the control unit further comprises a detection module configured to monitor the voltage of the bootstrap capacitor of each phase bridge arm circuit in real time, and in the case that the voltage of any bootstrap capacitor is less than the preset threshold, the bootstrap capacitor with the voltage less than the preset threshold is charged according to a preset third pulse width modulation signal, and the third pulse width modulation signal is a constant duty cycle modulation signal.

[0061] In the above embodiment, by monitoring the voltage state of the bootstrap capacitor of each phase bridge arm circuit in real time, and immediately supplementing power based on the third pulse width modulation signal with constant duty cycle when the voltage is lower than the preset threshold, the continuous and stable supply of the first bridge arm driving voltage is realized, and the failure of power devices or abnormal operation of the motor caused by insufficient driving voltage is prevented. The power supplement strategy of the present scheme responds quickly and can restore the bootstrap capacitor voltage to the normal range in a very short time. The constant duty cycle signal helps to reduce the charging current impact and electromagnetic interference, and reduces the bus and phase point voltage ripple. At the same time, it avoids frequent deep discharge of the bootstrap capacitor, reduces the thermal stress of the power device and the driver, and prolongs the service life. Through the above method, the continuity of the three-phase drive output is ensured, and the reliability and stability of the equipment under long-time operation are ensured.

[0062] Specifically, when driving the first bridge arm, the gate voltage of the driving chip of the first bridge arm must be higher than the source voltage by at least a specified minimum voltage value, in order to ensure that the power switch device can be reliably turned on. The above minimum value is between 10V and 12V, depending on the type and specification of the device. Once the voltage provided by the bootstrap capacitor is lower than this value, the driving chip of the first bridge arm may not be fully turned on or the switching speed may be slow, the waveform may be distorted, or even it may not be turned on, resulting in motor start failure or jitter. Therefore, the preset threshold is the minimum bootstrap voltage value to ensure the normal operation of the high-side drive.

[0063] In some other exemplary embodiments, the device further comprises a pre-charging unit for pre-charging each bootstrap capacitor with a direct current power supply to make the voltage of each bootstrap capacitor reach a preset initial voltage value.

[0064] In the above embodiment, before entering the normal charging control based on the first and second pulse width modulation signals, each bootstrap capacitor is pre-charged by a direct current power supply, so that each bootstrap capacitor has a certain initial voltage reserve in advance, thereby ensuring that the high-side drive circuit can immediately obtain stable driving voltage at the initial power-on stage, and avoiding the failure of the high-side power device to be turned on or unstable turn-on due to the too low initial voltage of the bootstrap capacitor. Thus, the bootstrap voltage establishment time in the start-up stage is shortened, the response speed of the motor start is improved, in addition, the peak current impact on the bus at the initial charging instant is reduced, thereby reducing the stress of the power device and the driving chip, and prolonging the service life of the device.

[0065] In an optional solution, the device further comprises a monitoring unit for monitoring the temperature of each bootstrap capacitor in real time, and suspending the charging of each bootstrap capacitor when the temperature of any bootstrap capacitor is greater than a preset temperature threshold, and resuming the charging of each bootstrap capacitor when the temperature of the bootstrap capacitor is less than or equal to the preset temperature threshold.

[0066] In the above embodiment, by monitoring the temperature of each bootstrap capacitor in real time, the charging process can be suspended in time when the temperature exceeds the preset safety threshold, thereby effectively preventing problems such as performance degradation, dielectric breakdown or failure caused by overheating of the capacitor. During the suspension of charging, the capacitor can be naturally cooled or cooled with the help of a cooling system, avoiding the accelerated wear of the capacitor life caused by continuous high temperature. When the temperature returns to the safe range, the charging is automatically resumed. Not only the safety of the drive circuit is improved, but also the increase of leakage current and energy loss caused by high temperature is reduced, ensuring the continuity and consistency of motor control.

[0067] The device for charging the bootstrap capacitor of the motor includes a processor and a memory, and the control unit and the like are stored in the memory as program units. The processor executes the above-mentioned program units stored in the memory to realize the corresponding functions. The above-mentioned modules are located in the same processor; or the above-mentioned modules are located in different processors in any combination.

[0068] The processor includes a core, and the core retrieves the corresponding program unit from the memory. The core can be set to one or more, and the core parameters are adjusted to at least solve the problem of unstable charging voltage of the motor at the initial stage of power-on, which leads to abnormal motor driving.

[0069] The memory can include non-permanent memory in a computer readable medium, random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one memory chip.

[0070] The embodiment of the application provides a computer readable storage medium, and the computer readable storage medium includes a stored program. When the program runs, the device where the computer readable storage medium is located executes the method for charging the bootstrap capacitor of the motor.

[0071] Specifically, the method for charging the bootstrap capacitor of the motor includes:

[0072] Step S101, receiving and responding to the instruction of power-on of the motor, controlling the first bridge arm of each phase bridge arm circuit according to the preset first pulse width modulation signal, and simultaneously controlling the second bridge arm of each phase bridge arm circuit according to the preset second pulse width modulation signal, to realize charging of the bootstrap capacitor in each phase bridge arm circuit,

[0073] The bridge arm circuit of each phase comprises a bootstrap capacitor, the bridge arm circuit of each phase is electrically connected with the U-phase winding, the V-phase winding and the W-phase winding of the motor respectively to drive the motor, the first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals, and the complementary pulse width modulation signals represent that only one of the first bridge arm and the second bridge arm in the bridge arm circuit of each phase is allowed to be turned on at any time period.

[0074] Specifically, the U-phase, the V-phase and the W-phase of the motor each have a group of bridge arm circuits comprising a first bridge arm and a second bridge arm, and the first bridge arm and the second bridge arm are each provided with a controllable switching device, and each phase of the bridge arm circuit comprises a bootstrap capacitor. In the case that the first bridge arm is turned off and the second bridge arm is turned on, the bootstrap capacitor is charged, and in the case that the first bridge arm is turned on and the second bridge arm is turned off, the bootstrap capacitor is isolated from the charging circuit.

[0075] According to the above embodiment, by receiving and responding to the instruction of power-on of the motor, the first bridge arm of each phase of the bridge arm circuit is controlled according to the preset first pulse width modulation signal, and the second bridge arm of each phase of the bridge arm circuit is controlled according to the preset second pulse width modulation signal, to realize charging of the bootstrap capacitor in each phase of the bridge arm circuit. According to the scheme, by simultaneously controlling the turn-on states of the first bridge arm and the second bridge arm of the three-phase bridge arm circuit when the motor is powered on, parallel charging of the bootstrap capacitor in each phase of the bridge arm circuit is realized, so that the voltage of the bootstrap capacitor is kept stable during the charging process, and the problem that the subsequent charging current is too large due to the rapid drop of the capacitor voltage in the charging mode of charging the capacitors in each phase of the bridge arm circuit respectively in the prior art is solved, and the problem that the charging voltage is unstable at the initial stage of power-on of the motor, resulting in abnormal motor driving, is solved.

[0076] In an embodiment of the present application, the first bridge arm of each phase of the bridge arm circuit is controlled according to the preset first pulse width modulation signal, and the second bridge arm of each phase of the bridge arm circuit is controlled according to the preset second pulse width modulation signal, comprising: adjusting the pulse width of the first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width according to a first preset function; adjusting the pulse width of the second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width according to a second preset function, the first preset initial pulse width is greater than the second preset initial pulse width, the first preset target pulse width is less than the second preset target pulse width, the first preset function is a monotonically decreasing function, and the second preset function is a monotonically increasing function.

[0077] In an embodiment of the present application, after the pulse width of the second pulse width modulation signal is adjusted from the second preset initial pulse width to the second preset target pulse width, the method further comprises: driving the second bridge arm in each phase bridge arm circuit according to the second preset target pulse width to charge the bootstrap capacitor until the voltage of the bootstrap capacitor reaches a preset threshold.

[0078] In an embodiment of the present application, after the bootstrap capacitor is charged until the voltage of the bootstrap capacitor reaches a preset threshold, the method further comprises: monitoring the voltage of the bootstrap capacitor of each phase bridge arm circuit in real time, and charging the bootstrap capacitor whose voltage is less than the preset threshold according to a preset third pulse width modulation signal if the voltage of any bootstrap capacitor is less than the preset threshold, the third pulse width modulation signal being a constant duty cycle modulation signal.

[0079] In an embodiment of the present application, the falling edge of the first pulse width modulation signal and the rising edge of the second pulse width modulation signal have a preset first time interval, and the falling edge of the second pulse width modulation signal and the rising edge of the first pulse width modulation signal have a preset second time interval, the first time interval being equal to the second time interval.

[0080] In an embodiment of the present application, before controlling the first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal and simultaneously controlling the second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, the method further comprises: pre-charging each bootstrap capacitor with a direct current power supply so that the voltage of the bootstrap capacitor reaches a preset initial voltage value.

[0081] In an embodiment of the present application, the method further comprises: monitoring the temperature of each bootstrap capacitor in real time, and suspending the charging of each bootstrap capacitor if the temperature of any bootstrap capacitor is greater than a preset temperature threshold, and resuming the charging of each bootstrap capacitor when the temperature of the bootstrap capacitor is less than or equal to the preset temperature threshold.

[0082] An embodiment of the present application provides a system for charging bootstrap capacitors of a motor, comprising a processor, a memory, and a program stored in the memory and executable on the processor, and the processor implements at least the following steps when executing the program:

[0083] Step S101, in response to an instruction of powering on the motor, controlling the first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal and simultaneously controlling the second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal to charge the bootstrap capacitor in each phase bridge arm circuit,

[0084] Each phase of the bridge arm circuit includes a bootstrap capacitor, the bridge arm circuit is electrically connected with the U-phase, V-phase and W-phase winding of the motor respectively to drive the motor, the first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals, and the complementary pulse width modulation signals represent that only one of the first bridge arm and the second bridge arm in each phase of the bridge arm circuit is allowed to conduct at any time period.

[0085] Specifically, the U-phase, V-phase and W-phase of the motor each have a group of bridge arm circuits including a first bridge arm and a second bridge arm, and the first bridge arm and the second bridge arm are each configured with a controllable switching device, and each phase of the bridge arm circuit includes a bootstrap capacitor. In the case that the first bridge arm is off and the second bridge arm is on, the bootstrap capacitor is charged, and in the case that the first bridge arm is on and the second bridge arm is off, the bootstrap capacitor is isolated from the charging circuit.

[0086] Through the above embodiment, by receiving and responding to the instruction of powering on the motor, the first bridge arm of each phase of the bridge arm circuit is controlled according to the preset first pulse width modulation signal, and the second bridge arm of each phase of the bridge arm circuit is controlled according to the preset second pulse width modulation signal at the same time, to realize charging of the bootstrap capacitor in each phase of the bridge arm circuit. The present scheme realizes parallel charging of the bootstrap capacitor in each phase of the bridge arm circuit by simultaneously controlling the conduction states of the first bridge arm and the second bridge arm of the three-phase bridge arm circuit when the motor is powered on, so that the voltage of the bootstrap capacitor remains stable during the charging process, avoiding the excessive subsequent charging current caused by the rapid decline of the capacitor voltage in the charging mode of charging the capacitor of each phase of the bridge arm circuit respectively in the prior art, and solving the problem of unstable charging voltage in the initial stage of powering on the motor in the prior art, which leads to abnormal motor driving.

[0087] In an embodiment of the present application, controlling the first bridge arm of each phase of the bridge arm circuit according to the preset first pulse width modulation signal and controlling the second bridge arm of each phase of the bridge arm circuit according to the preset second pulse width modulation signal at the same time includes: adjusting the pulse width of the first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width according to a first preset function; adjusting the pulse width of the second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width according to a second preset function, the first preset initial pulse width is greater than the second preset initial pulse width, the first preset target pulse width is less than the second preset target pulse width, the first preset function is a monotonically decreasing function, and the second preset function is a monotonically increasing function.

[0088] In an embodiment of the present application, after the pulse width of the second pulse width modulation signal is adjusted from the second preset initial pulse width to the second preset target pulse width, the method further comprises: driving the second bridge arm in each phase bridge arm circuit according to the second preset target pulse width to charge the bootstrap capacitor until the voltage of the bootstrap capacitor reaches a preset threshold.

[0089] In an embodiment of the present application, after the bootstrap capacitor is charged until the voltage of the bootstrap capacitor reaches a preset threshold, the method further comprises: monitoring the voltage of the bootstrap capacitor of each phase bridge arm circuit in real time, and charging the bootstrap capacitor whose voltage is less than the preset threshold according to a preset third pulse width modulation signal if the voltage of any bootstrap capacitor is less than the preset threshold, the third pulse width modulation signal being a constant duty cycle modulation signal.

[0090] In an embodiment of the present application, the falling edge of the first pulse width modulation signal and the rising edge of the second pulse width modulation signal have a preset first time interval, and the falling edge of the second pulse width modulation signal and the rising edge of the first pulse width modulation signal have a preset second time interval, the first time interval being equal to the second time interval.

[0091] In an embodiment of the present application, before the first bridge arm of each phase bridge arm circuit is controlled according to a preset first pulse width modulation signal and the second bridge arm of each phase bridge arm circuit is controlled according to a preset second pulse width modulation signal, the method further comprises: pre-charging each bootstrap capacitor with a direct current power supply so that the voltage of the bootstrap capacitor reaches a preset initial voltage value.

[0092] In an embodiment of the present application, the method further comprises: monitoring the temperature of each bootstrap capacitor in real time, and suspending the charging of each bootstrap capacitor if the temperature of any bootstrap capacitor is greater than a preset temperature threshold, and resuming the charging of each bootstrap capacitor when the temperature of the bootstrap capacitor is less than or equal to the preset temperature threshold.

[0093] The device herein can be a server, a PC, a PAD, a mobile phone, etc.

[0094] It should be apparent to those skilled in the art that the modules or steps of the application described above can be implemented with a general purpose computer, and can be centralized in a single computer or distributed among a network of computers, and can be implemented with program code executable by a computer, and thus can be stored in a storage device and executed by a computer, and in some cases, the steps shown or described can be executed in a different order than shown or described, or can be implemented as separate integrated circuit modules or as a single integrated circuit module, and thus the application is not limited to any particular combination of hardware and software.

[0095] Those skilled in the art will appreciate that embodiments of the application can be devised for a method, a system, or a computer program product. Accordingly, the application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the application can be in the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk memory, CD-ROMs, optical storage media, etc.) embodying computer readable program code.

[0096] The present application is described herein with reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0097] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0098] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams.Figure 1 one or more processes and / or blocks Figure 1 the function(s) specified in the flow block or blocks.

[0099] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0100] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) about which the processor can read instructions stored thereon for execution; and non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), flash memory, or other solid state memory technology. The memory is an example of computer readable media.

[0101] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer readable media does not include transitory media such as modulated data signals and carrier waves.

[0102] The technical features of the above-described embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the scope of the specification includes all possible combinations.

[0103] It should also be noted that the terms "comprising", "comprises", "including", "includes" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article or apparatus that includes the element.

[0104] From the above description, it can be seen that the above-mentioned embodiments of the application achieve the following technical effects:

[0105] 1) The method for charging the bootstrap capacitor of the motor according to the application receives and responds to the instruction of powering on the motor, controls the first bridge arm of each phase bridge arm circuit according to the preset first pulse width modulation signal, and simultaneously controls the second bridge arm of each phase bridge arm circuit according to the preset second pulse width modulation signal, to realize the charging of the bootstrap capacitor in each phase bridge arm circuit. The present scheme controls the conduction state of the first bridge arm and the second bridge arm of the three-phase bridge arm circuit at the same time when the motor is powered on, realizes the parallel charging of the bootstrap capacitor in each phase bridge arm circuit, keeps the voltage of the bootstrap capacitor stable during the charging process, avoids the excessive subsequent charging current caused by the rapid drop of the capacitor voltage in the charging mode of charging the capacitor of each phase bridge arm circuit respectively in the prior art, and solves the problem of unstable charging voltage at the initial stage of powering on the motor in the prior art, which leads to the abnormal driving of the motor.

[0106] 2) The device for charging the bootstrap capacitor of the motor according to the application receives and responds to the instruction of powering on the motor through the control unit, controls the first bridge arm of each phase bridge arm circuit according to the preset first pulse width modulation signal, and simultaneously controls the second bridge arm of each phase bridge arm circuit according to the preset second pulse width modulation signal, to realize the charging of the bootstrap capacitor in each phase bridge arm circuit. The present scheme controls the conduction state of the first bridge arm and the second bridge arm of the three-phase bridge arm circuit at the same time when the motor is powered on, realizes the parallel charging of the bootstrap capacitor in each phase bridge arm circuit, keeps the voltage of the bootstrap capacitor stable during the charging process, avoids the excessive subsequent charging current caused by the rapid drop of the capacitor voltage in the charging mode of charging the capacitor of each phase bridge arm circuit respectively in the prior art, and solves the problem of unstable charging voltage at the initial stage of powering on the motor in the prior art, which leads to the abnormal driving of the motor.

[0107] The above only describes the preferred embodiments of the application and is not intended to limit the application. Those skilled in the art can make various changes and modifications to the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for charging a motor's bootstrap capacitor, characterized in that, include: Upon receiving and responding to the command to power on the motor, the system controls the first arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously controls the second arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, thereby charging the bootstrap capacitor in each phase bridge arm circuit. Each phase of the bridge arm circuit includes a bootstrap capacitor. The bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the motor to drive the motor. The first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals. The complementary pulse width modulation signal indicates that only one of the first bridge arm and the second bridge arm in each phase of the bridge arm circuit is allowed to conduct at any given time. According to the first preset function, the pulse width of the first pulse width modulation signal is adjusted from the first preset initial pulse width to the first preset target pulse width; According to the second preset function, the pulse width of the second pulse width modulation signal is adjusted from the second preset initial pulse width to the second preset target pulse width. The first preset initial pulse width is greater than the second preset initial pulse width, the first preset target pulse width is less than the second preset target pulse width, the first preset function is a monotonically decreasing function, and the second preset function is a monotonically increasing function.

2. The method according to claim 1, characterized in that, After adjusting the pulse width of the second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width, the method further includes: According to the second preset target pulse width, drive the second bridge arm in each phase of the bridge arm circuit to charge the bootstrap capacitor until the voltage of the bootstrap capacitor reaches a preset threshold.

3. The method according to claim 2, characterized in that, After charging the bootstrap capacitor until its voltage reaches a preset threshold, the method further includes: The voltage of the bootstrap capacitor in each phase of the bridge arm circuit is monitored in real time, and if the voltage of any bootstrap capacitor is less than the preset threshold, the bootstrap capacitor with a voltage less than the preset threshold is charged according to a preset third pulse width modulation signal, wherein the third pulse width modulation signal is a modulation signal with a constant duty cycle.

4. The method according to claim 1, characterized in that, There is a preset first time interval between the falling edge of the first pulse width modulation signal and the rising edge of the second pulse width modulation signal, and there is a preset second time interval between the falling edge of the second pulse width modulation signal and the rising edge of the first pulse width modulation signal, wherein the first time interval is equal to the second time interval.

5. The method according to claim 1, characterized in that, Before controlling the first arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously controlling the second arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, the method further includes: Each of the bootstrap capacitors is pre-charged using a DC power supply so that the voltage of the bootstrap capacitors reaches a preset initial voltage value.

6. The method according to claim 1, characterized in that, The method further includes: The temperature of each bootstrap capacitor is monitored in real time, and if the temperature of any bootstrap capacitor is greater than a preset temperature threshold, charging of each bootstrap capacitor is paused until the temperature of the bootstrap capacitor is less than or equal to the preset temperature threshold, at which point charging of each bootstrap capacitor is resumed.

7. A device for charging a bootstrap capacitor of an electric motor, characterized in that, include: The control unit receives and responds to the command to power on the motor, controls the first arm of each phase arm circuit according to a preset first pulse width modulation signal, and simultaneously controls the second arm of each phase arm circuit according to a preset second pulse width modulation signal, so as to charge the bootstrap capacitor in each phase arm circuit. Each phase of the bridge arm circuit includes a bootstrap capacitor. The bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the motor to drive the motor. The first pulse width modulation signal and the second pulse width modulation signal are complementary pulse width modulation signals. The complementary pulse width modulation signal indicates that only one of the first bridge arm and the second bridge arm in each phase of the bridge arm circuit is allowed to conduct at any given time. The first adjustment module is used to adjust the pulse width of the first pulse width modulation signal from the first preset initial pulse width to the first preset target pulse width according to the first preset function. The second adjustment module is used to adjust the pulse width of the second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width according to a second preset function. The first preset initial pulse width is greater than the second preset initial pulse width, the first preset target pulse width is less than the second preset target pulse width, the first preset function is a monotonically decreasing function, and the second preset function is a monotonically increasing function.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform the method according to any one of claims 1 to 6.

9. A system for self-charging a motor's bootstrap capacitor, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising methods for performing any one of claims 1 to 6.

Images