Bootstrap capacitor charging method and device of motor, storage medium and system

Abstract

The invention provides a bootstrap capacitor charging method, device, storage medium and system for a motor, and the method comprises the steps: receiving and responding to a motor power-on instruction, and controlling a first bridge arm of each phase of bridge arm circuit according to a preset first pulse width modulation signal, and meanwhile, a second bridge arm of each phase of bridge arm circuit is controlled according to a preset second pulse width modulation signal so as to charge a bootstrap capacitor in each phase of bridge arm circuit, each phase of bridge arm circuit comprises a bootstrap capacitor, and the bridge arm circuits are electrically connected with a U-phase winding, a V-phase winding and a W-phase winding of the motor so as 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 bridge arm circuit is allowed to be conducted in any time period. According to the invention, the problem of abnormal motor driving caused by unstable charging voltage at the initial stage of motor electrification in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the field of motor control and power electronics technology, and in particular to a method for charging a bootstrap capacitor of a motor, an apparatus 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 Art

[0002] During operation, a permanent magnet synchronous motor's control circuitry typically requires a stable DC power supply to support the inverter and other electronic components. The purpose of charging the bootstrap capacitor is to provide the necessary voltage to the IGBT (insulated gate bipolar transistor) drive circuit in the upper-arm circuit, ensuring proper operation. In a three-phase inverter, each arm consists of two IGBTs (insulated gate bipolar transistors): an upper arm connected to the positive bus and a lower arm connected to the negative bus. Because there is no direct voltage source between the emitter of the upper-arm IGBT and the positive bus, a bootstrap circuit is required to power the upper-arm drive circuit. During motor startup, the bootstrap capacitor must be charged to store sufficient energy to ensure the upper-arm IGBT can be properly turned on and off.

[0003] Traditionally, the bootstrap capacitor charging method uses three bridge arms with the same constant duty cycle, with the upper and lower IGBTs charging the bootstrap capacitor with complementary pulse widths. Because the capacitor is empty before charging, charging with a high duty cycle can momentarily lower the drive power supply voltage or cause excessive charging current to trigger the motor's overcurrent protection. Charging with a low duty cycle can result in prolonged charging, affecting the timely start-up of the motor. Summary of the Invention

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

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a method for charging the bootstrap capacitor of a motor is provided, comprising: receiving and responding to an instruction to power 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, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit, wherein each phase bridge arm circuit includes one bootstrap capacitor, and the bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the motor, respectively, to drive the motor, and 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 indicate 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 in any time period.

[0006] Optionally, 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 at the same time, including: according to a first preset function, 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 second 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, 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 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: 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.

[0008] Optionally, after charging the bootstrap capacitor until the voltage of the bootstrap capacitor reaches a preset threshold, the method further includes: monitoring the voltage of the bootstrap capacitor of each phase of the bridge arm circuit in real time, and when the voltage of any bootstrap capacitor is less than the preset threshold, charging the bootstrap capacitor with a voltage less than the preset threshold 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.

[0009] Optionally, 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, 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 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 includes: using a DC power supply to pre-charge each of the bootstrap capacitors so that the voltage of the bootstrap capacitor reaches a preset initial voltage value.

[0011] Optionally, the method further includes: monitoring the temperature of each of the bootstrap capacitors in real time, and suspending charging of each of the bootstrap capacitors when the temperature of any of the bootstrap capacitors is greater than a preset temperature threshold, and resuming charging of each of the bootstrap capacitors 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, a device for charging the bootstrap capacitor of a motor is provided, comprising: a control unit for receiving and responding to an instruction to power 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, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit, wherein each phase bridge arm circuit includes one bootstrap capacitor, and the bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the motor, respectively, to drive the motor, and 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 indicate 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 in any time period.

[0013] According to another aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute any one of the methods described.

[0014] According to another aspect of the present application, a system for charging the bootstrap capacitor of a motor is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include methods for executing any one of the methods described.

[0015] By applying the technical solution of the present application, by receiving and responding to the motor power-on instruction, 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, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit. This solution realizes parallel charging of the bootstrap capacitor in each phase bridge arm circuit by simultaneously controlling the conduction state 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 maintains a steady rise during the charging process, avoiding the subsequent excessive charging current caused by the rapid drop of the capacitor voltage under the charging method of charging each phase bridge arm circuit separately in the prior art, and solving the problem of unstable charging voltage in the initial stage of motor power-on, which leads to abnormal motor drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

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

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

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

[0020] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. 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 invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

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

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

[0025] Figure 1 FIG. 1 is a flow chart of a method for charging the bootstrap capacitor of a motor according to an embodiment of the present application. Figure 1 As shown, the method includes the following steps:

[0026] Step S101: receiving and responding to a motor power-on instruction, 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, so as to charge the bootstrap capacitor in each phase bridge arm circuit.

[0027] In which, each phase of the above-mentioned bridge arm circuit includes the above-mentioned bootstrap capacitor, and the above-mentioned bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the above-mentioned motor respectively to drive the above-mentioned motor. The above-mentioned first pulse width modulation signal and the above-mentioned second pulse width modulation signal are complementary pulse width modulation signals, and the above-mentioned complementary pulse width modulation signals indicate that in any time period, only one of the above-mentioned first bridge arm and the above-mentioned second bridge arm in the above-mentioned bridge arm circuit of each phase is allowed to be turned on.

[0028] Specifically, each of the motor's U, V, and W phases has a bridge arm circuit comprising a first bridge arm and a second bridge arm. Both the first and second bridge arms are equipped with controllable switching devices, and each bridge arm circuit includes a bootstrap capacitor. When the first bridge arm is off and the second bridge arm is on, the bootstrap capacitor charges. When the first bridge arm is on and the second bridge arm is off, the bootstrap capacitor is isolated from the charging circuit.

[0029] Through the above embodiment, by receiving and responding to the motor power-on instruction, 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, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit. This solution realizes parallel charging of the bootstrap capacitor in each phase bridge arm circuit by simultaneously controlling the conduction state 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 maintains a steady rise during the charging process, avoiding the subsequent excessive charging current caused by the rapid drop of the capacitor voltage under the charging method of charging each phase bridge arm circuit separately in the prior art, and solves the problem of unstable charging voltage in the initial stage of motor power-on, which leads to abnormal motor drive.

[0030] In an optional 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 at the same time, including: according to a first preset function, adjusting the pulse width of the above-mentioned first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width; according to a second preset function, adjusting the above-mentioned pulse width of the above-mentioned second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width, the above-mentioned first preset initial pulse width is greater than the above-mentioned second preset initial pulse width, the above-mentioned first preset target pulse width is less than the above-mentioned second preset target pulse width, the above-mentioned first preset function is a monotonically decreasing function, and the above-mentioned second preset function is a monotonically increasing function.

[0031] In the above embodiment, by using a first preset function to perform a monotonically decreasing gradual control on the conduction pulse width of the first bridge arm, and using a second preset function to perform a monotonically increasing gradual control on the conduction pulse width of the second bridge arm, the conduction window of the bootstrap capacitor is gradually lengthened, and the charging opportunities are more intensive, thereby making the voltage of the bootstrap capacitor rise smoothly, avoiding the voltage fluctuations and incomplete charging problems caused by time-sharing charging in the prior art. At the same time, the change in pulse width follows the preset function, effectively suppressing the instantaneous large current impact caused by the sudden increase in duty cycle, reducing the risk of triggering overcurrent protection, and protecting the safety of power devices. Furthermore, the conduction duty cycle of the first bridge arm is gradually reduced, that is, the conduction time of the first bridge arm is shortened, which means that the total conduction loss of the first bridge arm will be reduced. The above-mentioned total conduction loss includes the loss on the on-resistance and the switching loss. The conduction duty cycle of the second bridge arm is gradually increased, that is, the conduction time of the second bridge arm is longer, giving more opportunities to charge the bootstrap capacitor, making the charging speed faster and more sufficient. Therefore, while the charging speed is fast enough, the bridge arm devices will not be subjected to large current conduction for a long time, avoiding excessive conduction losses, thereby making the overall efficiency of the entire system higher, which can not only fully charge quickly but also reduce heat and power waste. Under the premise of ensuring the charging speed, the conduction time ratio of the two bridge arms is adjusted to the optimal ratio to achieve a balance between charging and loss.

[0032] Specifically, the first and second preset initial pulse widths are determined based on the bootstrap capacitor capacity, bus voltage, and the safe operating area of ​​the switching device. The bootstrap voltage rise curve at different duty cycles can be measured through simulation or oscilloscope testing, and the duty cycle that can increase the capacitor voltage to 70% to 85% of the required drive voltage within 1 to 3 pulse-width modulation cycles can be selected as the initial pulse width. For example, if the pulse-width modulation cycle is 20 µs, an initial pulse width of 10 to 12 µs can be selected.

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

[0034] 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 with the second preset target pulse width until the capacitor voltage reaches the preset threshold, thereby forming a stable and predictable charging stage. Through the above method, each phase is charged in parallel under the same strategy, so that the bootstrap capacitor voltage of each phase is raised in unison, the inter-phase voltage deviation is reduced, the symmetry of the three-phase drive is improved, and the success rate and stability of the motor start-up are improved. At the same time, charging with 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, and achieve a dynamic balance between the charging rate and the power device loss. While ensuring the rapid establishment of the bootstrap voltage, it reduces the thermal stress and energy waste of the device, so that the overall operating efficiency of the system reaches the best state.

[0035] In some exemplary embodiments, after charging the bootstrap capacitor until the voltage of the bootstrap capacitor reaches a preset threshold, the method further includes: monitoring the voltage of the bootstrap capacitor of each phase of the bridge arm circuit in real time, and when the voltage of any of the bootstrap capacitors is less than the preset threshold, charging the bootstrap capacitor with a voltage less than the preset threshold 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.

[0036] In the above embodiment, by monitoring the voltage state of the bootstrap capacitor of each phase bridge arm circuit in real time, and immediately performing power replenishment based on the third pulse width modulation signal with a constant duty cycle when the voltage is lower than the preset threshold, a continuous and stable supply of the driving voltage of the first bridge arm is achieved, thereby preventing power device failure or abnormal motor operation due to insufficient driving voltage. The power replenishment strategy of this solution responds quickly and can restore the bootstrap capacitor voltage to a normal range in a very short time, and the constant duty cycle signal helps to reduce charging current shock and electromagnetic interference, and reduce bus and phase 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 extends the service life. Through the above method, the continuity of the three-phase drive output is guaranteed, and the reliability and stability of the equipment under long-term operation are guaranteed.

[0037] Specifically, when the driver chip of the first bridge arm drives the first bridge arm, the gate voltage of the driver chip must be higher than the source voltage by at least a specified minimum voltage value to ensure reliable conduction of the power switch device. This minimum value is between 10V and 12V, depending on the device type and specifications. If the voltage provided by the bootstrap capacitor falls below this value, the driver chip of the first bridge arm may not fully turn on, or may experience slow switching speed, waveform distortion, or even no conduction at all, resulting in motor startup failure or jitter. Therefore, the preset threshold is the minimum bootstrap voltage value that ensures normal operation of the high-side drive.

[0038] In other exemplary embodiments, there is a preset first time interval between the falling edge of the above-mentioned first pulse width modulation signal and the rising edge of the above-mentioned second pulse width modulation signal, and there is a preset second time interval between the above-mentioned falling edge of the above-mentioned second pulse width modulation signal and the above-mentioned rising edge of the above-mentioned first pulse width modulation signal, and the above-mentioned first time interval is equal to the above-mentioned second time interval.

[0039] In the above embodiment, by setting equal time intervals, i.e., dead time, between the falling edge of the first pulse width modulation signal and the rising edge of the second pulse width modulation signal, and between the falling edge of the second pulse width modulation signal and the rising edge of the first pulse width modulation signal, during the switching process of the same phase bridge arm, the symmetrical dead time ensures that the first bridge arm and the second bridge arm will not be turned on at the same time at the switching moment, effectively avoiding bus overcurrent and power device damage caused by direct short circuit, thereby improving the safety of the system. The symmetrical switching delay prevents the bootstrap capacitor from being impacted by high-voltage transients during bridge arm switching, reduces the fluctuation of the capacitor charging voltage, ensures that a stable bootstrap voltage can be obtained, and thus reduces the risk of jitter and failure during motor startup. In addition, the equality of the first time interval and the second time interval avoids transient current offset caused by unbalanced switching timing of the three-phase bridge arm, and reduces bus voltage ripple and phase point voltage disturbance.

[0040] Specifically, the falling edge is the moment when the pulse modulation signal jumps from a high level to a low level, which means that the controlled bridge arm is turned off, and the rising edge is the moment when the pulse modulation signal jumps from a low level to a high level, which means that the controlled bridge arm is turned on. The first time interval is the delay from the falling edge of the first pulse width modulation signal, that is, the first bridge arm is turned off, to the rising edge of the second pulse width modulation signal, that is, the second bridge arm is turned on. The second time interval is the delay from the falling edge of the second pulse width modulation signal, that is, the second bridge arm is turned off, to the rising edge of the first pulse width modulation signal, that is, the first bridge arm is turned on. The equality of the first time interval and the second time interval indicates that during the complementary drive switching process, the dead times in the two directions are symmetrical.

[0041] In some exemplary schemes 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 above method also includes: using a DC power supply to pre-charge each of the above bootstrap capacitors so that the voltage of the above bootstrap capacitor reaches a preset initial voltage value.

[0042] In the above embodiment, before entering normal charging control based on the first and second pulse-width modulation signals, each bootstrap capacitor is precharged via a DC power supply, so that each bootstrap capacitor has a certain initial voltage reserve in advance. This ensures that the high-side drive circuit can immediately obtain a stable drive voltage at the initial power-up stage, avoiding the high-side power device from failing to turn on in time or turning on unstably due to the initial voltage of the bootstrap capacitor being too low. This shortens the bootstrap voltage buildup time during the startup phase, improving the response speed of motor startup. In addition, it also reduces the peak inrush current on the busbar during the initial charging moment, thereby reducing the stress on the power device and driver chip and extending the device's service life.

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

[0044] 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 a preset safety threshold, thereby effectively preventing problems such as performance degradation, dielectric breakdown or failure caused by capacitor overheating. During the suspension of charging, the capacitor can dissipate heat naturally or cool down with the help of a heat dissipation system, avoiding the accelerated loss of capacitor life due to continuous high temperature. When the temperature returns to a safe range, charging is automatically resumed. This not only improves the safety of the drive circuit, but also reduces the increase in leakage current and energy loss caused by high temperature, ensuring the continuity and consistency of motor control.

[0045] The embodiment of the present application provides a specific implementation scenario for charging the motor bootstrap capacitor. In this embodiment, each phase bridge arm circuit consists of a first bridge arm and a second bridge arm, and is equipped with a corresponding bootstrap capacitor. Figure 2As shown, where T is a pulse width modulation cycle, up, vp, and wp are the pulse width control signals for the first bridge arm of the three-phase motor's U phase, V phase, and W phase, respectively, and un, vn, and wn are the pulse width control signals for the second bridge arm of the three-phase motor's U phase, V phase, and W phase, respectively. In the first state, when the pulse width control signal of the first bridge arm is high and the pulse width control signal of the second bridge arm is low, 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, V phase, and W phase are isolated from the circuit and are in an uncharged state. In the second state, when the pulse width control signal of the first bridge arm is low and the pulse width control signal of the second bridge arm is high, 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, V phase, and W phase all begin 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 PWM signal in the second bridge arm gradually increases from small to large, while the pulse width of the PWM signal in the first bridge arm gradually decreases from large to small. The change in pulse width, Δt = t2 - t1, is the increase in the conduction time of the second bridge arm or the decrease in the conduction time of the first bridge arm. This adjustment range is set between 5% and 10% of the total duty cycle based on the bus power supply capacity and the required charging speed. To prevent the upper and lower transistors in the same bridge arm from turning on simultaneously, a dead time is inserted between the shutdown of the first bridge arm and the turn-on of the second bridge arm, and between the shutdown of the second bridge arm and the turn-on of the first bridge arm. This dead time is defined as the intervals Δt1 and Δt2 between the rising and falling edges of the un, vn, and wn pulse widths and the falling and rising edges of the up, vp, and wp pulse widths. This interval is determined by the switching characteristics of the power devices and is typically 1 to 4 μs. When the pulse width of the pulse width modulation signal of the second bridge arm increases to a preset maximum value, the duty cycle will be maintained until the bootstrap capacitor is fully charged. The entire constant pulse width charging phase t3 is usually completed within 100 ms.

[0046] The present application also provides a specific implementation scenario in which the initial pulse width of a pulse-width modulated signal gradually changes to a target pulse width according to a monotonic function. In this embodiment, the motor drive system comprises a three-phase inverter bridge structure, wherein 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 drive circuit. The three phases correspond to the 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 command and begins charging the bootstrap capacitor. During the initial charging phase, the duty cycle of the first pulse-width modulated signal used to control the first bridge arm is set to a high value, such as 60%, to quickly establish a sufficient bootstrap voltage for the high-side driver. As the charging process progresses, the duty cycle is gradually reduced to a target value, such as 20%, according to a preset first monotonic decreasing function to reduce conduction losses and device stress. The function shape and start and end values ​​can be pre-calibrated based on the bootstrap capacitor capacity, bus voltage, and the safe operating area of ​​the power device. The second pulse width modulation signal used to control the second bridge arm has a low duty cycle, such as 20%, in the initial charging stage to avoid excessive charging current shocks at the beginning of charging. The duty cycle is gradually increased to a target value, such as 60%, according to a preset second monotonically increasing function, so that the low-side conduction time gradually increases, the charging opportunities increase, and the distribution is more even. The function curve can also be optimized through simulation or oscilloscope measurement to balance charging speed and device loss. The above-mentioned 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 in any time period. When the signal is alternately turned on, symmetrical first and second dead time are inserted to prevent direct short circuits and reduce the instantaneous high voltage stress on the bootstrap capacitor when the bridge arm switches. Through the above scheme, the gradual extension of the low-side conduction time makes the charging process of the bootstrap capacitor show a slow rising curve, avoiding the obvious fluctuations in 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 drive signal is more reliable. In addition, the duty cycle changes gradually as a function, avoiding the capacitor charging current impact caused by instantaneous large duty cycle, reducing the probability of the driver chip or controller falsely triggering overcurrent protection; at the same time, protecting power devices from instantaneous large current stress, extending device life, and improving circuit safety.

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

[0048] The embodiment of the present application also provides a device for charging the bootstrap capacitor of a motor. It should be noted that the device for charging the bootstrap capacitor of a motor in the embodiment of the present application can be used to execute the method for charging the bootstrap capacitor of a motor provided in the embodiment of the present application. The device is used to implement the above-mentioned embodiments and preferred implementation methods, and those that have been explained will not be repeated here. As used below, the term "module" can implement a combination of software and / or hardware for a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and conceived.

[0049] The following introduces the device for charging the bootstrap capacitor of the motor provided in the embodiment of the present application.

[0050] Figure 3 Schematic diagram of a device for charging the bootstrap capacitor of a motor according to an embodiment of the present application. Figure 3 As shown, the device includes:

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

[0052] In which, each phase of the above-mentioned bridge arm circuit includes the above-mentioned bootstrap capacitor, and the above-mentioned bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the above-mentioned motor respectively to drive the above-mentioned motor. The above-mentioned first pulse width modulation signal and the above-mentioned second pulse width modulation signal are complementary pulse width modulation signals, and the above-mentioned complementary pulse width modulation signals indicate that in any time period, only one of the above-mentioned first bridge arm and the above-mentioned second bridge arm in the above-mentioned bridge arm circuit of each phase is allowed to be turned on.

[0053] Specifically, each of the motor's U, V, and W phases has a bridge arm circuit comprising a first bridge arm and a second bridge arm. Both the first and second bridge arms are equipped with controllable switching devices, and each bridge arm circuit includes a bootstrap capacitor. When the first bridge arm is off and the second bridge arm is on, the bootstrap capacitor charges. When the first bridge arm is on and the second bridge arm is off, the bootstrap capacitor is isolated from the charging circuit.

[0054] Through the above embodiment, the control unit receives and responds to the motor power-on instruction, controls the first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously controls the second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit. This solution realizes parallel charging of the bootstrap capacitor in each phase bridge arm circuit by simultaneously controlling the conduction state 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 maintains a steady rise during the charging process, avoiding the subsequent excessive charging current caused by the rapid drop of the capacitor voltage under the charging method of charging each phase bridge arm circuit separately in the prior art, and solves the problem of unstable charging voltage in the initial stage of motor power-on, which leads to abnormal motor drive in the prior art.

[0055] As an optional solution, the above-mentioned control unit includes: a first adjustment module, used to adjust the pulse width of the above-mentioned 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; a second adjustment module, used to adjust the above-mentioned pulse width of the above-mentioned 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 above-mentioned first preset initial pulse width is greater than the above-mentioned second preset initial pulse width, the above-mentioned first preset target pulse width is less than the above-mentioned second preset target pulse width, the above-mentioned first preset function is a monotonically decreasing function, and the above-mentioned second preset function is a monotonically increasing function.

[0056] In the above embodiment, by using a first preset function to perform a monotonically decreasing gradual control on the conduction pulse width of the first bridge arm, and using a second preset function to perform a monotonically increasing gradual control on the conduction pulse width of the second bridge arm, the conduction window of the bootstrap capacitor is gradually lengthened, and the charging opportunities are more intensive, thereby making the voltage of the bootstrap capacitor rise smoothly, avoiding the voltage fluctuations and incomplete charging problems caused by time-sharing charging in the prior art. At the same time, the change in pulse width follows the preset function, effectively suppressing the instantaneous large current impact caused by the sudden increase in duty cycle, reducing the risk of triggering overcurrent protection, and protecting the safety of power devices. Furthermore, the conduction duty cycle of the first bridge arm is gradually reduced, that is, the conduction time of the first bridge arm is shortened, which means that the total conduction loss of the first bridge arm will be reduced. The above-mentioned total conduction loss includes the loss on the on-resistance and the switching loss. The conduction duty cycle of the second bridge arm is gradually increased, that is, the conduction time of the second bridge arm is longer, giving more opportunities to charge the bootstrap capacitor, making the charging speed faster and more sufficient. Therefore, while the charging speed is fast enough, the bridge arm devices will not be subjected to large current conduction for a long time, avoiding excessive conduction losses, thereby making the overall efficiency of the entire system higher, which can not only fully charge quickly but also reduce heat and power waste. Under the premise of ensuring the charging speed, the conduction time ratio of the two bridge arms is adjusted to the optimal ratio to achieve a balance between charging and loss.

[0057] Specifically, the first and second preset initial pulse widths are determined based on the bootstrap capacitor capacity, bus voltage, and the safe operating area of ​​the switching device. The bootstrap voltage rise curve at different duty cycles can be measured through simulation or oscilloscope testing, and the duty cycle that can increase the capacitor voltage to 70% to 85% of the required drive voltage within 1 to 3 pulse-width modulation cycles can be selected as the initial pulse width. For example, if the pulse-width modulation cycle is 20 µs, an initial pulse width of 10 to 12 µs can be selected.

[0058] In an optional solution, the control unit further includes: a driving module for 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.

[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 with the second preset target pulse width until the capacitor voltage reaches the preset threshold, thereby forming a stable and predictable charging stage. Through the above method, each phase is charged in parallel under the same strategy, so that the bootstrap capacitor voltage of each phase is raised in unison, the inter-phase voltage deviation is reduced, the symmetry of the three-phase drive is improved, and the success rate and stability of the motor start-up are improved. At the same time, charging with 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, and achieve a dynamic balance between the charging rate and the power device loss. While ensuring the rapid establishment of the bootstrap voltage, it reduces the thermal stress and energy waste of the device, so that the overall operating efficiency of the system reaches the best state.

[0060] In some exemplary embodiments, the control unit further includes: a detection module for monitoring the voltage of the bootstrap capacitor of each phase of the bridge arm circuit in real time, and when the voltage of any of the bootstrap capacitors is less than the preset threshold, charging the bootstrap capacitor with a voltage less than the preset threshold 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.

[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 performing power replenishment based on the third pulse width modulation signal with a constant duty cycle when the voltage is lower than the preset threshold, a continuous and stable supply of the driving voltage of the first bridge arm is achieved, thereby preventing power device failure or abnormal motor operation due to insufficient driving voltage. The power replenishment strategy of this solution responds quickly and can restore the bootstrap capacitor voltage to a normal range in a very short time, and the constant duty cycle signal helps to reduce charging current shock and electromagnetic interference, and reduce bus and phase 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 extends the service life. Through the above method, the continuity of the three-phase drive output is guaranteed, and the reliability and stability of the equipment under long-term operation are guaranteed.

[0062] Specifically, when the driver chip of the first bridge arm drives the first bridge arm, the gate voltage of the driver chip must be higher than the source voltage by at least a specified minimum voltage value to ensure reliable conduction of the power switch device. This minimum value is between 10V and 12V, depending on the device type and specifications. If the voltage provided by the bootstrap capacitor falls below this value, the driver chip of the first bridge arm may not fully turn on, or may experience slow switching speed, waveform distortion, or even no conduction at all, resulting in motor startup failure or jitter. Therefore, the preset threshold is the minimum bootstrap voltage value that ensures normal operation of the high-side drive.

[0063] In some other exemplary embodiments, the apparatus further includes: a pre-charging unit configured to pre-charge each of the bootstrap capacitors using a DC power supply so that the voltage of the bootstrap capacitor reaches a preset initial voltage value.

[0064] In the above embodiment, before entering normal charging control based on the first and second pulse-width modulation signals, each bootstrap capacitor is precharged via a DC power supply, so that each bootstrap capacitor has a certain initial voltage reserve in advance. This ensures that the high-side drive circuit can immediately obtain a stable drive voltage at the initial power-up stage, avoiding the high-side power device from failing to turn on in time or turning on unstably due to the initial voltage of the bootstrap capacitor being too low. This shortens the bootstrap voltage buildup time during the startup phase, improving the response speed of motor startup. In addition, it also reduces the peak inrush current on the busbar during the initial charging moment, thereby reducing the stress on the power device and driver chip and extending the device's service life.

[0065] In an optional solution, the above-mentioned device also includes: a monitoring unit, which is used to monitor the temperature of each of the above-mentioned bootstrap capacitors in real time, and suspend the charging of each of the above-mentioned bootstrap capacitors when the temperature of any of the above-mentioned bootstrap capacitors is greater than a preset temperature threshold, and resume the charging of each of the above-mentioned bootstrap capacitors until the temperature of the above-mentioned bootstrap capacitors 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 a preset safety threshold, thereby effectively preventing problems such as performance degradation, dielectric breakdown or failure caused by capacitor overheating. During the suspension of charging, the capacitor can dissipate heat naturally or cool down with the help of a heat dissipation system, avoiding the accelerated loss of capacitor life due to continuous high temperature. When the temperature returns to a safe range, charging is automatically resumed. This not only improves the safety of the drive circuit, but also reduces the increase in leakage current and energy loss caused by high temperature, ensuring the continuity and consistency of motor control.

[0067] The motor bootstrap capacitor charging device includes a processor and memory. The control unit and other components are stored in the memory as program units, and the processor executes the program units stored in the memory to implement the corresponding functions. The modules are all located in the same processor; alternatively, the modules can be located in different processors in any combination.

[0068] The processor includes a core, which retrieves the corresponding program unit from the memory. One or more cores can be provided, and by adjusting the core parameters, at least the problem of unstable charging voltage during the initial stage of motor power-up, which leads to abnormal motor drive, in the prior art, can be solved.

[0069] The memory may 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 RAM, and the memory includes at least one memory chip.

[0070] An embodiment of the present invention provides a computer-readable storage medium, which includes a stored program. When the program is executed, the device containing the computer-readable storage medium is controlled to execute 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 a motor power-on instruction, 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, so as to charge the bootstrap capacitor in each phase bridge arm circuit.

[0073] In which, each phase of the above-mentioned bridge arm circuit includes the above-mentioned bootstrap capacitor, and the above-mentioned bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the above-mentioned motor respectively to drive the above-mentioned motor. The above-mentioned first pulse width modulation signal and the above-mentioned second pulse width modulation signal are complementary pulse width modulation signals, and the above-mentioned complementary pulse width modulation signals indicate that in any time period, only one of the above-mentioned first bridge arm and the above-mentioned second bridge arm in the above-mentioned bridge arm circuit of each phase is allowed to be turned on.

[0074] Specifically, each of the motor's U, V, and W phases has a bridge arm circuit comprising a first bridge arm and a second bridge arm. Both the first and second bridge arms are equipped with controllable switching devices, and each bridge arm circuit includes a bootstrap capacitor. When the first bridge arm is off and the second bridge arm is on, the bootstrap capacitor charges. When the first bridge arm is on and the second bridge arm is off, the bootstrap capacitor is isolated from the charging circuit.

[0075] Through the above embodiment, by receiving and responding to the motor power-on instruction, 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, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit. This solution realizes parallel charging of the bootstrap capacitor in each phase bridge arm circuit by simultaneously controlling the conduction state 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 maintains a steady rise during the charging process, avoiding the subsequent excessive charging current caused by the rapid drop of the capacitor voltage under the charging method of charging each phase bridge arm circuit separately in the prior art, and solves the problem of unstable charging voltage in the initial stage of motor power-on, which leads to abnormal motor drive.

[0076] In one embodiment of the present application, 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, including: according to a first preset function, adjusting the pulse width of the above-mentioned first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width; according to a second preset function, adjusting the above-mentioned pulse width of the above-mentioned second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width, the above-mentioned first preset initial pulse width is greater than the above-mentioned second preset initial pulse width, the above-mentioned first preset target pulse width is less than the above-mentioned second preset target pulse width, the above-mentioned first preset function is a monotonically decreasing function, and the above-mentioned second preset function is a monotonically increasing function.

[0077] In one embodiment of the present application, 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 includes: 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 the voltage of the bootstrap capacitor reaches a preset threshold.

[0078] In one embodiment of the present application, after charging the above-mentioned bootstrap capacitor until the voltage of the above-mentioned bootstrap capacitor reaches a preset threshold value, the above-mentioned method further includes: monitoring the above-mentioned voltage of the above-mentioned bootstrap capacitor of each phase of the above-mentioned bridge arm circuit in real time, and when the above-mentioned voltage of any of the above-mentioned bootstrap capacitors is less than the above-mentioned preset threshold value, charging the above-mentioned bootstrap capacitor whose voltage is less than the above-mentioned preset threshold value according to a preset third pulse width modulation signal, wherein the above-mentioned third pulse width modulation signal is a modulation signal with a constant duty cycle.

[0079] In one embodiment of the present application, there is a preset first time interval between the falling edge of the above-mentioned first pulse width modulation signal and the rising edge of the above-mentioned second pulse width modulation signal, and there is a preset second time interval between the above-mentioned falling edge of the above-mentioned second pulse width modulation signal and the above-mentioned rising edge of the above-mentioned first pulse width modulation signal, and the above-mentioned first time interval is equal to the above-mentioned second time interval.

[0080] In one 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 above method also includes: using a DC power supply to pre-charge each of the above bootstrap capacitors so that the voltage of the above bootstrap capacitor reaches a preset initial voltage value.

[0081] In one embodiment of the present application, the above method also includes: real-time monitoring of the temperature of each of the above bootstrap capacitors, and when the temperature of any of the above bootstrap capacitors is greater than a preset temperature threshold, suspending the charging of each of the above bootstrap capacitors until the temperature of the above bootstrap capacitor is less than or equal to the preset temperature threshold, and then resuming the charging of each of the above bootstrap capacitors.

[0082] An embodiment of the present invention provides a system for charging a bootstrap capacitor of a motor, comprising a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, at least the following steps are implemented:

[0083] Step S101: receiving and responding to a motor power-on instruction, 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, so as to charge the bootstrap capacitor in each phase bridge arm circuit.

[0084] In which, each phase of the above-mentioned bridge arm circuit includes the above-mentioned bootstrap capacitor, and the above-mentioned bridge arm circuit is electrically connected to the U-phase, V-phase, and W-phase windings of the above-mentioned motor respectively to drive the above-mentioned motor. The above-mentioned first pulse width modulation signal and the above-mentioned second pulse width modulation signal are complementary pulse width modulation signals, and the above-mentioned complementary pulse width modulation signals indicate that in any time period, only one of the above-mentioned first bridge arm and the above-mentioned second bridge arm in the above-mentioned bridge arm circuit of each phase is allowed to be turned on.

[0085] Specifically, each of the motor's U, V, and W phases has a bridge arm circuit comprising a first bridge arm and a second bridge arm. Both the first and second bridge arms are equipped with controllable switching devices, and each bridge arm circuit includes a bootstrap capacitor. When the first bridge arm is off and the second bridge arm is on, the bootstrap capacitor charges. When 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 motor power-on instruction, 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, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit. This solution realizes parallel charging of the bootstrap capacitor in each phase bridge arm circuit by simultaneously controlling the conduction state 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 maintains a steady rise during the charging process, avoiding the subsequent excessive charging current caused by the rapid drop of the capacitor voltage under the charging method of charging each phase bridge arm circuit separately in the prior art, and solves the problem of unstable charging voltage in the initial stage of motor power-on, which leads to abnormal motor drive.

[0087] In one embodiment of the present application, 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, including: according to a first preset function, adjusting the pulse width of the above-mentioned first pulse width modulation signal from a first preset initial pulse width to a first preset target pulse width; according to a second preset function, adjusting the above-mentioned pulse width of the above-mentioned second pulse width modulation signal from a second preset initial pulse width to a second preset target pulse width, the above-mentioned first preset initial pulse width is greater than the above-mentioned second preset initial pulse width, the above-mentioned first preset target pulse width is less than the above-mentioned second preset target pulse width, the above-mentioned first preset function is a monotonically decreasing function, and the above-mentioned second preset function is a monotonically increasing function.

[0088] In one embodiment of the present application, 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 includes: 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 the voltage of the bootstrap capacitor reaches a preset threshold.

[0089] In one embodiment of the present application, after charging the above-mentioned bootstrap capacitor until the voltage of the above-mentioned bootstrap capacitor reaches a preset threshold value, the above-mentioned method further includes: monitoring the above-mentioned voltage of the above-mentioned bootstrap capacitor of each phase of the above-mentioned bridge arm circuit in real time, and when the above-mentioned voltage of any of the above-mentioned bootstrap capacitors is less than the above-mentioned preset threshold value, charging the above-mentioned bootstrap capacitor whose voltage is less than the above-mentioned preset threshold value according to a preset third pulse width modulation signal, wherein the above-mentioned third pulse width modulation signal is a modulation signal with a constant duty cycle.

[0090] In one embodiment of the present application, there is a preset first time interval between the falling edge of the above-mentioned first pulse width modulation signal and the rising edge of the above-mentioned second pulse width modulation signal, and there is a preset second time interval between the above-mentioned falling edge of the above-mentioned second pulse width modulation signal and the above-mentioned rising edge of the above-mentioned first pulse width modulation signal, and the above-mentioned first time interval is equal to the above-mentioned second time interval.

[0091] In one 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 above method also includes: using a DC power supply to pre-charge each of the above bootstrap capacitors so that the voltage of the above bootstrap capacitor reaches a preset initial voltage value.

[0092] In one embodiment of the present application, the above method also includes: real-time monitoring of the temperature of each of the above bootstrap capacitors, and when the temperature of any of the above bootstrap capacitors is greater than a preset temperature threshold, suspending the charging of each of the above bootstrap capacitors until the temperature of the above bootstrap capacitor is less than or equal to the preset temperature threshold, and then resuming the charging of each of the above bootstrap capacitors.

[0093] The devices in this article can be servers, PCs, PADs, mobile phones, etc.

[0094] Obviously, those skilled in the art will appreciate that the various modules or steps of the present invention described above can be implemented using a general-purpose computing device, can be centralized on a single computing device, or can be distributed across a network of multiple computing devices. They can be implemented using program code executable by the computing device, and thus, can be stored in a storage device and executed by the computing device. In some cases, the steps shown or described herein can be performed in a different order than that shown, or can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0095] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0097] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0098] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

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

[0100] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

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

[0102] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

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

[0105] 1) The method for charging the bootstrap capacitor of the motor of the present application receives and responds to the motor power-on instruction, controls the first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously controls the second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit. This solution realizes parallel charging of the bootstrap capacitors in each phase bridge arm circuit by simultaneously controlling the conduction state 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 keeps rising steadily during the charging process, avoiding the subsequent excessive charging current caused by the rapid drop of the capacitor voltage under the charging method of charging the capacitor of each phase bridge arm circuit separately in the prior art, and solves the problem of unstable charging voltage in the initial stage of motor power-on, which leads to abnormal motor drive in the prior art.

[0106] 2) The device for charging the bootstrap capacitor of the motor of the present application receives and responds to the motor power-on instruction through the control unit, controls the first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously controls the second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, so as to realize charging of the bootstrap capacitor in each phase bridge arm circuit. This solution realizes parallel charging of the bootstrap capacitors in each phase bridge arm circuit by simultaneously controlling the conduction state 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 keeps rising steadily during the charging process, avoiding the subsequent excessive charging current caused by the rapid drop of the capacitor voltage under the charging method of charging the capacitor of each phase bridge arm circuit separately in the prior art, and solves the problem of unstable charging voltage in the initial stage of motor power-on, which leads to abnormal motor drive in the prior art.

[0107] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Persons skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for charging a bootstrap capacitor of a motor, characterized in that: include: receiving and responding to a motor power-on instruction, 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, so as to charge the bootstrap capacitor in each phase bridge arm circuit, Each phase of the bridge arm circuit includes one bootstrap capacitor, and the bridge arm circuit is electrically connected to the 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 indicate that only one of the first bridge arm and the second bridge arm in each phase of the bridge arm circuit is allowed to be turned on in any time period. According to a first preset function, 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 second preset function, the pulse width of the second pulse width modulation signal is adjusted from a second preset initial pulse width to a 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, the second bridge arm in the bridge arm circuit of each phase is driven 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 the voltage of the bootstrap capacitor reaches a preset threshold, the method further includes: The voltage of the bootstrap capacitor of the bridge arm circuit of each phase is monitored in real time, and when 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, wherein the third pulse width modulation signal is a modulation signal with a constant duty cycle.

4. The method according to claim 1, wherein 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, and the first time interval is equal to the second time interval.

5. The method according to claim 1, wherein Before 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, the method further includes: A DC power supply is used to pre-charge each of the bootstrap capacitors so that the voltage of the bootstrap capacitor reaches a preset initial voltage value.

6. The method according to claim 1, characterized in that The method further comprises: The temperature of each bootstrap capacitor is monitored in real time, and when the temperature of any bootstrap capacitor is greater than a preset temperature threshold, charging of each bootstrap capacitor is suspended until the temperature of the bootstrap capacitor is less than or equal to the preset temperature threshold, then charging of each bootstrap capacitor is resumed.

7. A device for charging a bootstrap capacitor of a motor, characterized in that: include: a control unit, configured to receive and respond to a motor power-on instruction, control the first bridge arm of each phase bridge arm circuit according to a preset first pulse width modulation signal, and simultaneously control the second bridge arm of each phase bridge arm circuit according to a preset second pulse width modulation signal, so as to charge the bootstrap capacitor in each phase bridge arm circuit, Each phase of the bridge arm circuit includes one bootstrap capacitor, and the bridge arm circuit is electrically connected to the 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 indicate that only one of the first bridge arm and the second bridge arm in each phase of the bridge arm circuit is allowed to be turned on in any time period. a first adjustment 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; A 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, wherein 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, the device where the computer-readable storage medium is located is controlled to execute the method according to any one of claims 1 to 6.

9. A system for charging a bootstrap capacitor of a motor, 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, and the one or more programs include instructions for executing the method of any one of claims 1 to 6.

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