A method and device for detecting short circuit of a capacitor in a motor bootstrap circuit

Abstract

The present invention provides a method and device for detecting a short circuit of a capacitor in a motor bootstrap circuit. The method for detecting a short circuit of a capacitor in a motor bootstrap circuit includes: sequentially outputting drive signals with a preset duty cycle to each phase of the motor to perform current detection on each phase of the motor, wherein the drive signals of other phases except the currently detected phase are empty; collecting the phase current data of the motor in each detected phase; and determining the detection result of the short circuit of the capacitor in the motor bootstrap circuit based on the magnitude relationship between the phase current data of different detected phases. By outputting drive signals with a preset duty cycle to each phase when the motor is powered on, the phase current data of each phase is obtained, and whether a short circuit fault occurs in the bootstrap circuit capacitor is judged according to the magnitude relationship between the phase currents, so as to realize rapid detection and response to the capacitor short circuit fault in the initial stage of the motor bootstrap circuit capacitor short circuit, avoid the motor from continuing to operate under the high risk of capacitor short circuit, and greatly reduce the occurrence of motor burnout situations.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and particularly to a method and device for detecting a short circuit of a bootstrap circuit capacitor of a motor. Background Art

[0002] With the mature development of technologies in the household appliance field and the rapid progress of power electronics technologies, permanent magnet synchronous motors with advantages such as low cost, high efficiency, and low noise are applied to more and more working scenarios. The emergence of intelligent power modules (IPMs) has further promoted the miniaturization and lightweight development of permanent magnet synchronous motor controllers. However, due to improper selection of the withstand voltage value of the capacitor or the occurrence of surge voltage during load operation, the bootstrap circuit capacitor may be broken down. The traditional detection of a short circuit of the bootstrap circuit capacitor of a permanent magnet synchronous motor controller is essentially achieved by open-phase protection and locked-rotor protection. However, this detection method has serious hysteresis and cannot detect the capacitor short circuit fault at the initial stage of the short circuit of the motor bootstrap circuit capacitor. If a short circuit of the bootstrap circuit capacitor occurs, the motor will operate at high risk and there is a hidden danger of burning out the machine. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that the capacitor short circuit fault cannot be detected at the initial stage of the short circuit of the motor bootstrap circuit capacitor. If a short circuit of the bootstrap circuit capacitor occurs, the motor will operate at high risk and there is a hidden danger of burning out the machine, so as to provide a method and device for detecting a short circuit of a motor bootstrap circuit capacitor.

[0004] According to a first aspect, an embodiment of the present invention provides a method for detecting a short circuit of a motor bootstrap circuit capacitor. A bootstrap circuit composed of a bootstrap capacitor is correspondingly arranged for each phase on the high voltage side of the motor. The method includes:

[0005] Sequentially output drive signals with a preset duty cycle to each phase of the motor to perform current detection on each phase of the motor, wherein the drive signals of other phases except the currently detected phase are empty;

[0006] Collect the phase current data of the motor at each detection phase;

[0007] Based on the magnitude relationship between the phase current data of different detection phases, determine the detection result of the short circuit of the motor bootstrap circuit capacitor.

[0008] Optionally, the collecting the phase current data of the motor at each detection phase includes:

[0009] Collect the current phase current of the motor at the currently detected phase according to a preset number of times;

[0010] Calculate the sum of all the collected current phase currents to obtain the phase current data of the currently detected phase.

[0011] Optionally, determining the detection result of the capacitor short circuit in the motor bootstrap circuit based on the magnitude relationship between the phase current data of different detection phases includes:

[0012] Sort the phase current data of different detection phases to determine the maximum phase current and the minimum phase current;

[0013] Judge whether the difference between the maximum phase current and the minimum phase current meets a preset difference condition;

[0014] When the difference between the maximum phase current and the minimum phase current meets the preset difference condition, determine that the capacitor in the motor bootstrap circuit is short-circuited;

[0015] When the difference between the maximum phase current and the minimum phase current does not meet the preset difference condition, determine that the capacitor in the motor bootstrap circuit is not short-circuited, and control the motor to run normally.

[0016] Optionally, after determining that the capacitor in the motor bootstrap circuit is short-circuited, the method further includes:

[0017] Determine the short-circuit location of the capacitor short circuit in the motor bootstrap circuit based on the detection phase corresponding to the maximum phase current;

[0018] Generate an alarm based on the short-circuit location.

[0019] Optionally, after determining that the capacitor in the motor bootstrap circuit is short-circuited, the method further includes:

[0020] Control the motor to stop.

[0021] Optionally, before sequentially outputting drive signals with a preset duty cycle to each phase of the motor, the method further includes:

[0022] Obtain the operating parameters of the motor;

[0023] Judge whether each of the operating parameters is within its corresponding preset range;

[0024] When each of the operating parameters is within its corresponding preset range, sequentially output drive signals with a preset duty cycle to each phase of the motor.

[0025] Optionally, the method further includes:

[0026] Obtain the operating state of the motor;

[0027] Judge whether the motor is starting for the first time;

[0028] When the motor is started for the first time, drive signals with a preset duty ratio are sequentially output to each phase of the motor to detect the current of each phase of the motor;

[0029] When the motor is not started for the first time, control the motor to run normally.

[0030] According to a second aspect, an embodiment of the present invention provides a device for detecting short circuits in boost circuit capacitors of a motor. A boost circuit composed of boost capacitors is correspondingly provided for each phase on the high-voltage side of the motor. The device includes:

[0031] An output module, configured to sequentially output drive signals with a preset duty ratio to each phase of the motor to detect the current of each phase of the motor, wherein the drive signals of other phases except the currently detected phase are empty;

[0032] An acquisition module, configured to acquire phase current data of the motor in each detected phase;

[0033] A judgment module, configured to determine the detection result of short circuits in the boost circuit capacitors of the motor based on the magnitude relationship between the phase current data of different detected phases.

[0034] According to a third aspect, an embodiment of the present invention provides a device for detecting short circuits in boost circuit capacitors of a motor. A boost circuit composed of boost capacitors is correspondingly provided for each phase on the high-voltage side of the motor. The device for detecting short circuits in the boost circuit capacitors of the motor includes: a motor controller, wherein the motor controller includes:

[0035] A memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to execute the method described in the first aspect or any optional implementation manner of the first aspect.

[0036] According to a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions for causing a computer to execute the method described in the first aspect or any optional implementation manner of the first aspect.

[0037] The technical solution of the present invention has the following advantages:

[0038] The method and device for detecting the short circuit of the bootstrap circuit capacitor of a motor provided by the present invention perform current detection on each phase of the motor by sequentially outputting drive signals with a preset duty cycle to each phase of the motor, wherein the drive signals of other phases except the currently detected phase are empty; collect the phase current data of the motor in each detected phase; and determine the detection result of the short circuit of the bootstrap circuit capacitor of the motor based on the magnitude relationship between the phase current data of different detected phases. By outputting drive signals with a preset duty cycle to each phase when the motor is powered on, the phase current data of each phase is obtained, and whether a short circuit fault occurs in the bootstrap circuit capacitor is judged according to the magnitude relationship between the phase currents, so as to realize the rapid detection and response to the capacitor short circuit fault in the initial stage of the short circuit of the bootstrap circuit capacitor of the motor, avoid the motor from continuing to operate in the high risk of capacitor short circuit, and greatly reduce the occurrence of motor burnout situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 Structural schematic diagram of the device for detecting the short circuit of the bootstrap circuit capacitor of the motor according to the embodiment of the present invention;

[0041] Figure 2 Schematic diagram of the U-phase bootstrap circuit of the method for detecting the short circuit of the bootstrap circuit capacitor of the motor according to the embodiment of the present invention;

[0042] Figure 3 Flowchart of the method for detecting the short circuit of the bootstrap circuit capacitor of the motor according to the embodiment of the present invention;

[0043] Figure 4 Flowchart for detecting the states of the U, V, and W phase bootstrap capacitors of the method for detecting the short circuit of the bootstrap circuit capacitor of the motor according to the embodiment of the present invention;

[0044] Figure 5 Fault retrieval flowchart of the method for detecting the short circuit of the bootstrap circuit capacitor of the motor according to the embodiment of the present invention;

[0045] Figure 6 Overall flowchart of the bootstrap capacitor short circuit protection of the method for detecting the short circuit of the bootstrap circuit capacitor of the motor according to the embodiment of the present invention;

[0046] Figure 7 Structural schematic diagram of the device for detecting the short circuit of the bootstrap circuit capacitor of the motor according to the embodiment of the present invention;

[0047] Figure 8Schematic diagram of the motor controller of a motor bootstrap circuit capacitor short - circuit detection device according to an embodiment of the present invention. Detailed implementation manners

[0048] The technical solutions of the present invention will be described clearly and completely below with reference to the accompanying drawings. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0049] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0051] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] An embodiment of the present invention provides a motor bootstrap circuit capacitor short - circuit detection device. As Figure 1 shown, the motor bootstrap circuit capacitor short - circuit detection device is composed of an intelligent power module 1 and a motor controller 2. A bootstrap circuit composed of bootstrap capacitors is correspondingly arranged for each phase on the high - voltage side of the motor.

[0053] Specifically, in practical applications, the intelligent power module 1 can be a high - voltage integrated circuit (HVIC), and the motor controller 2 can be a motor controller state machine. For the specific working principle and working process of the motor controller 2, refer to the relevant descriptions in the method embodiment below, and details will not be repeated here.

[0054] As Figure 2As shown in the figure, taking the U-phase bootstrap circuit of a permanent magnet synchronous motor as an example, the intelligent power module 1 includes the floating power supply terminal (VB) of the U-phase high-side gate drive, the internal chip power supply voltage (Vcc), the low-side control signal input terminal (INL), the IPM module ground terminal (COM), the U-phase high-side control signal input terminal (HO), the U-phase high-side control signal input terminal (LO). VS is connected to the U-phase winding of the motor and is used to drive the motor. Among them, the internal chip power supply voltage can be 15V; the U-phase high-side control signal is used to drive the on-off of the upper-bridge IGBT; the U-phase high-side control signal is used to drive the on-off of the lower-bridge IGBT.

[0055] The V-phase bootstrap circuit and the W-phase bootstrap circuit have the same structure as the U-phase bootstrap circuit. The corresponding VS ports are respectively connected to the V-phase winding of the motor and the W-phase winding of the motor and are used to drive the motor, which will not be elaborated here.

[0056] The working principle of the U-phase bootstrap circuit is as follows: When the intelligent power module 1 starts, the IGBT on the low side of the U phase is turned on, and the CC voltage charges the bootstrap capacitor through the bootstrap diode, so that VB and VS reach 15V to drive a group of IGBTs on the high side of the U phase and then drive the motor to run. The working principles of the V-phase and W-phase bootstrap circuits are similar to that of the U-phase bootstrap circuit, which will not be elaborated here.

[0057] An embodiment of the present invention provides a method for detecting a short circuit of a motor bootstrap circuit capacitor, which is applied to the motor controller 2 of a motor bootstrap circuit capacitor short circuit detection device. As Figure 3 shown, the method for detecting a short circuit of the motor bootstrap circuit capacitor specifically includes the following steps:

[0058] Step S101: Sequentially output drive signals with a preset duty cycle to each phase of the motor to detect the current of each phase of the motor. Among them, the drive signals of other phases except the currently detected phase are empty.

[0059] Specifically, in practical applications, in order to better detect the current of each phase in the embodiment of the present invention, the drive signals with a preset duty cycle are set according to different phases. By inputting a corresponding special duty cycle signal to the currently detected phase, the current of the currently detected phase is detected specifically.

[0060] Specifically, in practical applications, the preset duty cycle signal in the embodiments of the present invention can be a three-phase pulse width modulation (PWM) duty cycle. The value of the preset duty cycle needs to be determined comprehensively according to the motor conditions and the performance of the single-chip microcomputer. If the value is too small, the phase current will be too small, resulting in the single-chip microcomputer being unable to collect the phase current data. If the value is too large, the motor will rotate, affecting the static current sampling. Exemplarily, the preset duty cycle can be 2000, but the actual situation is not limited to this. Changing the value of the preset duty cycle drive signal to ensure accurate judgment of whether a capacitor short circuit fault occurs is also within the protection scope of the motor bootstrap circuit capacitor short circuit detection method provided by the embodiments of the present invention.

[0061] Step S102: Collect the phase current data of the motor at each detection phase.

[0062] Specifically, in practical applications, the embodiments of the present invention implement the switching of the detection phase by controlling the motor controller. When the detection phase is determined, the phase current data of the motor at the current detection phase will be collected. After the collection is completed, the next detection phase will be switched until the phase current data of the three detection phases are completed.

[0063] Step S103: Determine the detection result of the capacitor short circuit in the motor bootstrap circuit based on the magnitude relationship between the phase current data of different detection phases.

[0064] Specifically, in practical applications, by comparing the magnitude relationship between the phase current data of different detection phases, the detection result of the capacitor short circuit in the motor bootstrap circuit can be quickly determined without adding additional equipment to detect whether a capacitor short circuit occurs in the bootstrap circuit. By making full use of the change situation that the phase current of the bootstrap circuit at this phase increases rapidly due to the capacitor short circuit in the bootstrap circuit, the phase position where the capacitor short circuit in the bootstrap circuit occurs can be quickly located, and the fault situation can be grasped in the first time, avoiding the occurrence of the situation where the motor is burned due to the capacitor short circuit in the bootstrap circuit.

[0065] By performing the above steps, the motor bootstrap circuit capacitor short circuit detection method provided by the embodiments of the present invention outputs a drive signal with a preset duty cycle to each phase when the motor is powered on, obtains the phase current data of each phase, and determines whether a short circuit fault occurs in the capacitor of the bootstrap circuit according to the magnitude relationship between the phase currents, realizing the rapid detection and response to the capacitor short circuit fault in the initial stage of the motor bootstrap circuit capacitor short circuit, avoiding the motor from continuing to operate in the high-risk situation of capacitor short circuit, and greatly reducing the occurrence of the situation of motor burnout.

[0066] Specifically, in one embodiment, before performing step S101 of sequentially outputting a drive signal with a preset duty cycle to each phase of the motor, the following steps are further included:

[0067] Step S201: Obtain the operating parameters of the motor.

[0068] Step S202: Determine whether each operating parameter is within its corresponding preset range.

[0069] Step S203: When each operating parameter is within its corresponding preset range, drive signals with a preset duty cycle are sequentially output to each phase of the motor.

[0070] Specifically, in practical applications, to better and effectively detect the short - circuit fault of the bootstrap circuit capacitor of the motor, the embodiments of the present invention will first obtain the operating parameters of the motor, initialize the AD sampling based on the single - chip microcomputer, and calibrate the operating parameters of the motor. When each operating parameter and the relevant parameters of the single - chip microcomputer are within their respective preset ranges, drive signals with a preset duty cycle are output to each phase of the motor. If each operating parameter and the relevant parameters of the single - chip microcomputer are not all within their respective preset ranges, continue to initialize the AD sampling and recalibrate each parameter until the parameter values are within their respective preset ranges.

[0071] By initializing the AD sampling and pre - calibrating the operating parameters before detecting the short - circuit of the bootstrap circuit capacitor of the motor, through initializing and calibrating each parameter, the accuracy of the subsequent short - circuit detection result of the bootstrap circuit capacitor is ensured.

[0072] Specifically, the operating parameters of the motor include the operational amplifier bias voltage value and the bus voltage value. Among them, when the range of the operational amplifier bias voltage value is 1.65V ± 10%, the range of the bus voltage value is greater than 40V. However, the actual situation is not limited to this, and the operating parameters of the motor can be selected according to the motor type, model, and usage requirements.

[0073] Specifically, in one embodiment, after performing the above - mentioned step S203, the following steps are further included:

[0074] Step S301: Obtain the operating state of the motor.

[0075] Step S302: Determine whether the motor is starting for the first time.

[0076] Step S303: When the motor is starting for the first time, drive signals with a preset duty cycle are sequentially output to each phase of the motor to detect the current of each phase of the motor.

[0077] Step S304: When the motor is not starting for the first time, control the motor to run normally.

[0078] Specifically, in practical applications, when all parameters are within the normal range, the motor controller will switch the operating state of the motor to the ready-to-run state. When the motor is in the ready-to-run state, it will determine whether the motor is starting for the first time. When the motor is starting for the first time, the motor controller sequentially outputs drive signals with a preset duty cycle to each phase of the motor to detect the current of each phase of the motor. When the motor is not starting for the first time, the motor controller will switch the operating state of the motor to the running state, thereby controlling the normal operation of the motor and ending the current motor bootstrap circuit capacitor short-circuit detection process.

[0079] According to the judgment result of whether the motor is starting for the first time, targeted detection of the short circuit of the capacitor in the motor bootstrap circuit is carried out. When the motor starts for the first time, due to the initial connection, a very high instantaneous overvoltage (i.e., surge voltage) will be generated. In most cases, the surge voltage will damage the circuit and its components, causing the capacitor in the bootstrap circuit to be broken down, posing a risk of burning the machine. By sequentially outputting drive signals with a preset duty cycle to each phase of the motor by the motor controller to detect the current of each phase of the motor, the fault is detected and eliminated in the initial stage of capacitor short circuit, avoiding the motor working in high risk and greatly improving the production efficiency. When the motor is not starting for the first time, since the capacitor short circuit detection of the motor bootstrap circuit has been carried out before to ensure the normal operation of the motor, there is no need to detect the capacitor short circuit fault of the motor bootstrap circuit again. While ensuring the normal operation of the motor, repeated detection is avoided, and the detection efficiency is greatly improved.

[0080] Specifically, in one embodiment, the above step S102 of collecting the phase current data of the motor at each detection phase specifically includes the following steps:

[0081] Step S401: Collect the current phase current of the motor at the current detection phase according to a preset number of times.

[0082] Step S402: Calculate the sum of all the collected current phase currents to obtain the phase current data of the current detection phase.

[0083] By collecting the current phase current of the motor at the current detection phase according to a preset number of times, the real-time acquisition of the phase current is realized. When a capacitor short circuit fault occurs, the value of the current phase current will increase suddenly in a short time, and it can be quickly determined that a capacitor short circuit fault occurs in the current detection phase, greatly reducing the risk of the motor being burned out due to capacitor short circuit. By calculating the sum of all the collected phase currents to obtain the phase current data of the current detection phase, it lays a foundation for comparing the three-phase currents in the follow-up. By accumulating the phase currents, the phase current difference between each phase is widened, making it easier for the staff to find the phase position where the fault occurs in the first time.

[0084] Specifically, in practical applications, such as Figure 4As shown in the figure, taking the U-phase bootstrap capacitor detection as an example, after entering the bootstrap capacitor detection state, if the current detection phase is the U-phase, a fixed duty cycle is set for the U-phase, and the duty cycles of the other two phases are set to 0. After the duty cycle is set, the U-phase current is collected and accumulated, and the number of accumulations is determined by the TIMECONSTANT value. The TIMECONSTANT value is calculated from the motor inductance parameter and the motor resistance parameter. It should be noted that the set duty cycle is not involved in the phase current calculation and is only used to detect the U-phase current. The same applies to the other two phases.

[0085] Specifically, when collecting the U-phase current, the U-duty cycle value is 2000V; the W-duty cycle value is 0; the W-duty cycle value is 0. At this time, the current sampling window of the U-phase is the largest, which is conducive to the collection of the U-phase current. When collecting the V-phase current and the W-phase current, the duty cycle value corresponding to the detected phase is set to 2000V, and the duty cycle values of the other two phases are 0, which will not be elaborated here.

[0086] Specifically, through the following formula, the value of the preset collection times TIMECONSTANT is calculated:

[0087]

[0088] Among them, R is the motor phase resistance, L is the motor phase inductance, and f is the PWM carrier frequency.

[0089] After the collection is completed, the accumulated data is recorded for subsequent fault retrieval. After the data recording is completed, the three-phase PWM output is set to consume the residual current until the self-bootstrapping capacitor detection of this phase is completed when the three-phase current is almost 0; the self-bootstrapping capacitor detection processes of the other two phases are the same as that of the U-phase, which will not be elaborated here.

[0090] Specifically, the three-phase PWM duty cycle for consuming the residual current can be a fixed duty cycle. Exemplarily, the duty cycle value is 1000V, that is, the U-duty cycle value is 1000V; the W-duty cycle value is 1000V; the W-duty cycle value is 1000V.

[0091] By giving a special PWM duty cycle through the motor controller during power-on to obtain the sampling current to judge whether there is a short-circuit fault in the bootstrap circuit capacitor of the motor controller, it realizes the rapid detection and response to the capacitor short-circuit fault in the initial stage of the motor bootstrap circuit capacitor short circuit, avoids the motor from continuing to operate in the high risk of capacitor short circuit, and greatly reduces the occurrence of motor burnout.

[0092] Specifically, in one embodiment, the above step S103 determines the short-circuit detection result of the motor bootstrap circuit capacitor based on the magnitude relationship between the phase current data of different detection phases, and specifically includes the following steps:

[0093] Step S501: Sort the phase current data of different detection phases to determine the maximum phase current and the minimum phase current.

[0094] Step S502: Determine whether the difference between the maximum phase current and the minimum phase current meets the preset difference condition.

[0095] Step S503: When the difference between the maximum phase current and the minimum phase current meets the preset difference condition, determine that the capacitor of the motor boost circuit is short-circuited.

[0096] Step S504: When the difference between the maximum phase current and the minimum phase current does not meet the preset difference condition, determine that the capacitor of the motor boost circuit is not short-circuited, and control the motor to run normally.

[0097] Specifically, in practical applications, as Figure 5 shown, when sorting the accumulated values of the phase currents obtained during the detection process of the boost capacitors of the U phase, V phase, and W phase, the maximum current accumulated value Sum_Max and the minimum current accumulated value Sum_Min are obtained. Comparing the two, if Sum_Max is much larger than Sum_Min, enter the fault retrieval state. In the fault retrieval state, compare Sum_Max with the accumulated values of the phase currents to obtain the phase with the short-circuited boost capacitor and output the corresponding short-circuit fault signal of the boost capacitor.

[0098] In the embodiment of the present invention, taking the multiple relationship as an example for illustration, determine whether Sum_Max is greater than Sum_Min (4 to 10 times), that is, when Sum_Max is greater than or equal to 4 times of Sum_Min, determine that the capacitor of the motor boost circuit is short-circuited; when Sum_Max is less than 4 times of Sum_Min, determine that the capacitor of the motor boost circuit is not short-circuited.

[0099] Through experiments, it is determined that a 4-fold difference relationship can obtain better detection effects, but the actual situation is not limited to this. The difference between the maximum phase current and the minimum phase current can be a difference relationship or a multiple relationship.

[0100] By directly using the magnitude relationship of the phase currents between the three phases, directly judge whether there is a short-circuit fault in the boost circuit capacitor. Without adding additional detection equipment, not only the detection efficiency of the capacitor short-circuit fault is greatly improved, but also the detection cost is reduced.

[0101] Specifically, in one embodiment, after performing the above step S503 to determine that the capacitor of the motor boost circuit is short-circuited, the following steps are further included:

[0102] Step S601: Determine the short-circuit position of the capacitor of the motor boost circuit based on the detection phase corresponding to the maximum phase current.

[0103] Step S602: Alarm based on the short-circuit position.

[0104] Specifically, in one embodiment, after performing the above step S503 to determine that the capacitor of the motor bootstrap circuit is short-circuited, the following steps are further included:

[0105] Step S603: Control the motor to stop.

[0106] Specifically, in practical applications, as Figure 5 shown, when Sum_Max is greater than or equal to 4 times of Sum_Min, it is determined that the capacitor of the motor bootstrap circuit is short-circuited. By comparing Sum_Max with Sum_U, Sum_V, and Sum_W respectively, the detection phase equal to the value of Sum_Max is determined as the short-circuit position of the capacitor of the motor bootstrap circuit. The motor is controlled to stop running and a fault signal is output until the fault is eliminated. While completing the fault retrieval, the technician is prompted to eliminate the short-circuit fault in time.

[0107] Specifically, after starting the detection of the short circuit of the capacitor of the bootstrap circuit, it is necessary to detect whether the capacitors of the bootstrap circuits of the three phases U, V, and W are short-circuited in sequence. If there is an abnormality, the motor is locked in the stop state and is not restarted, without relying on the Hall sensor circuit.

[0108] Figure 6 Illustrates the whole process of the three-phase bootstrap capacitor short-circuit detection and triggering corresponding protection for the occurred bootstrap capacitor short-circuit phenomenon when the motor controller runs for the first time. When the initialization of the motor controller is completed, the AD sampling is turned on, and the parameters required for the normal operation of the motor, such as the bias voltage and the bus voltage, are collected. When all the parameters are within the normal error range, the controller state is switched to the ready-to-run state. After entering the ready-to-run state, if this start is the first start of the motor, the controller state will be switched to detecting the state of the bootstrap capacitor of phase x, where x can be U, V, or W; otherwise, it is switched to the running state; when the controller state enters the state of detecting the three-phase bootstrap capacitors, it is necessary to detect the three-phase bootstrap capacitors in sequence and record the current data; subsequently, the motor controller enters the fault retrieval state and analyzes the previously recorded current data. If there is a short circuit in any phase of the bootstrap capacitor, the controller state is switched to the bootstrap capacitor short-circuit protection state, and the motor stops running and issues a corresponding fault signal. If there is no short circuit in the bootstrap capacitor, the motor controller returns to the running state again.

[0109] By performing the above steps, the method for detecting the short circuit of the bootstrap circuit capacitor provided by the embodiment of the present invention outputs drive signals with a preset duty cycle to each phase when the motor is powered on, obtains the phase current data of each phase, and determines whether a short circuit fault occurs in the bootstrap circuit capacitor according to the magnitude relationship between the phase currents. By using the given special duty cycle and comparing the relationship between the phase currents, it is possible to quickly detect and respond to the capacitor short circuit fault at the initial stage of the short circuit of the motor bootstrap circuit capacitor, avoid the motor from continuing to operate in the high risk of capacitor short circuit, and greatly reduce the occurrence of motor burnout situations.

[0110] Next, a specific application example will be used to elaborate in detail on the method for detecting the short circuit of the bootstrap circuit capacitor provided by the embodiment of the present invention.

[0111] As shown in Figures 1-6 When a permanent magnet synchronous motor starts normally (without a short circuit in the bootstrap capacitor), after the motor controller initializes, it detects the state of the three-phase bootstrap capacitors by detecting the three-phase currents. If no abnormality is detected, the motor controller enters the normal operation state, and the motor starts normally and enters the closed-loop control operation state;

[0112] When a permanent magnet synchronous motor starts abnormally (with a short circuit in any phase of the bootstrap capacitor), after the motor controller initializes, it detects the state of the three-phase bootstrap capacitors by detecting the three-phase currents. If an abnormality is detected, the motor controller enters the fault protection state, the motor stops running, and sends a corresponding fault signal to the host computer until the fault is eliminated.

[0113] The specific control logic is as follows:

[0114] After the motor controller initializes, it collects parameters such as the bias voltage and the bus voltage and ensures that these parameters are within the normal error range. Subsequently, it detects the number of motor starts. If this start is the first start of the motor, the motor controller enters the self-check state of the three-phase bootstrap capacitors, detects the three-phase bootstrap capacitors in sequence, and simultaneously records the three-phase current data during the detection. The process of detecting the three-phase bootstrap capacitors is as follows: First, detect phase U, set the PWM output of phase U to a fixed duty cycle, and set the PWM output duty cycles of the other two phases to zero. Then, collect and accumulate the current of phase U. After the collection is completed, save the accumulated value for retrieval. Finally, set the PWM outputs of all three phases to a fixed duty cycle to consume the residual current until the three-phase currents are almost zero. Then, detect phases V and W in sequence in the same way as phase U.

[0115] After all three-phase bootstrap capacitors are detected, the motor controller starts to perform a fault search. The specific search process is to sort the cumulative current values of each phase recorded during the three-phase bootstrap capacitor detection, and select the maximum value Sum_Max and the minimum value Sum_Min among the cumulative current values of the three phases. If the maximum value Sum_Max is much larger than the minimum value Sum_Min, it is determined that a bootstrap capacitor short circuit occurs in one phase, and the phase with the largest cumulative current value of the three-phase current is the phase where the bootstrap capacitor short circuit occurs. After determining the phase with the bootstrap capacitor short circuit, the motor controller will protect and stop the machine and output the corresponding bootstrap capacitor short circuit fault signal until the fault is eliminated.

[0116] The method for detecting a short circuit of a capacitor in a motor bootstrap circuit provided by an embodiment of the present invention is also applicable to IGBT short circuit detection and motor winding short circuit protection, realizing rapid detection and response to capacitor short circuit faults in the initial stage of a short circuit in the motor bootstrap circuit, avoiding the motor from continuing to operate in a high-risk state of capacitor short circuit, and greatly reducing the occurrence of motor burnout.

[0117] An embodiment of the present invention provides a device for detecting a short circuit of a capacitor in a motor bootstrap circuit. A bootstrap circuit composed of bootstrap capacitors is correspondingly arranged at each phase of the high-voltage side of the motor, as Figure 7 shown. The device for detecting a short circuit of a capacitor in the motor bootstrap circuit includes:

[0118] An output module 101, configured to sequentially output drive signals with a preset duty cycle to each phase of the motor to detect the current of each phase of the motor, where the drive signals of other phases except the currently detected phase are empty. For detailed content, refer to the relevant description of step S101 in the above method embodiment, and details will not be repeated here.

[0119] A collection module 102, configured to collect the phase current data of the motor at each detection phase. For detailed content, refer to the relevant description of step S102 in the above method embodiment, and details will not be repeated here.

[0120] A judgment module 103, configured to determine the detection result of a short circuit of a capacitor in the motor bootstrap circuit based on the magnitude relationship between the phase current data of different detection phases. For detailed content, refer to the relevant description of step S103 in the above method embodiment, and details will not be repeated here.

[0121] For a further description of the above device for detecting a short circuit of a capacitor in a motor bootstrap circuit, refer to the relevant description of the embodiment of the method for detecting a short circuit of a capacitor in a motor bootstrap circuit above, and details will not be repeated here.

[0122] Through the collaborative cooperation of the above-mentioned various components, the motor bootstrap circuit capacitor short-circuit detection device provided by the embodiment of the present invention outputs drive signals with a preset duty cycle to each phase when the motor is powered on, obtains the phase current data of each phase, and determines whether the bootstrap circuit capacitor has a short-circuit fault according to the magnitude relationship between the phase currents, realizing the rapid detection and response to the capacitor short-circuit fault at the initial stage of the motor bootstrap circuit capacitor short-circuit, avoiding the motor from continuing to operate in the high risk of capacitor short-circuit, and greatly reducing the occurrence of motor burnout situations.

[0123] The motor controller 2 of the motor bootstrap circuit capacitor short-circuit detection device provided by the embodiment of the present invention is as Figure 8 shown. The motor controller 2 includes a processor 901 and a memory 902, and the memory 902 and the processor 901 are communicatively connected to each other. Among them, the processor 901 and the memory 902 can be connected by a bus or other means. Figure 8 Here, the case of connection by a bus is taken as an example.

[0124] The processor 901 can be a central processing unit (CPU). The processor 901 can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. chips, or combinations of the above types of chips.

[0125] The memory 902, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the methods in the embodiments of the present invention. The processor 901 executes various functional applications and data processing of the processor 901 by running the non-transitory software programs, instructions, and modules stored in the memory 902, that is, implements the methods in the above method embodiments.

[0126] The memory 902 may include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created by the processor 901 and the like. In addition, the memory 902 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory 902 may optionally include memories remotely provided with respect to the processor 901, and these remote memories can be connected to the processor 901 through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0127] One or more modules are stored in the memory 902 and, when executed by the processor 901, execute the methods in the above method embodiments.

[0128] For specific details of the above-mentioned motor controller 2, reference can be made to the corresponding relevant descriptions and effects in the above method embodiments for understanding, and details will not be repeated here.

[0129] Those skilled in the art can understand that to implement all or part of the processes in the above method embodiments, it can be completed by instructing relevant hardware through a computer program. The implemented program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above method embodiments. Among them, the storage medium can be a magnetic disk, an optical disc, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above types of memories.

[0130] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for detecting capacitor short circuit in a motor bootstrap circuit, characterized in that, A bootstrap circuit composed of bootstrap capacitors is correspondingly arranged for each phase on the high-voltage side of the motor. The method includes: Sequentially output drive signals with a preset duty cycle to each phase of the motor to perform current detection on each phase of the motor. Among them, the drive signals of other phases except the current detection phase are empty; Collect the phase current data of the motor in each detection phase; Based on the magnitude relationship between the phase current data of different detection phases, determine the detection result of the short circuit of the capacitor in the motor bootstrap circuit; The determining the detection result of the short circuit of the capacitor in the motor bootstrap circuit based on the magnitude relationship between the phase current data of different detection phases includes: Sort the phase current data of different detection phases to determine the maximum phase current and the minimum phase current; Judge whether the difference between the maximum phase current and the minimum phase current meets a preset difference condition; When the difference between the maximum phase current and the minimum phase current meets the preset difference condition, determine that the capacitor in the motor bootstrap circuit is short-circuited.

2. The method according to claim 1, wherein The collecting the phase current data of the motor in each detection phase includes: Collect the current phase current of the motor in the current detection phase according to a preset number of times; Calculate the sum of all the collected current phase currents to obtain the phase current data of the current detection phase.

3. The method according to claim 1, wherein The determining the detection result of the short circuit of the capacitor in the motor bootstrap circuit based on the magnitude relationship between the phase current data of different detection phases further includes: When the difference between the maximum phase current and the minimum phase current does not meet the preset difference condition, determine that the capacitor in the motor bootstrap circuit is not short-circuited, and control the motor to operate normally.

4. The method according to claim 3, wherein After determining that the capacitor in the motor bootstrap circuit is short-circuited, the method further includes: Based on the detection phase corresponding to the maximum phase current, determine the short-circuit position of the short circuit of the capacitor in the motor bootstrap circuit; Alarm based on the short-circuit position.

5. The method according to claim 3, characterized in that After determining that the capacitor in the motor bootstrap circuit is short-circuited, the method further includes: Control the motor to stop.

6. The method according to claim 1, characterized in that, Before sequentially outputting drive signals with a preset duty cycle to each phase of the motor, the method further includes: Obtain the operating parameters of the motor; Judge whether each of the operating parameters is within its corresponding preset range; When each of the operating parameters is within its corresponding preset range, sequentially output drive signals with a preset duty cycle to each phase of the motor.

7. The method according to claim 1, wherein The method further includes: Obtain the operating state of the motor; Judge whether the motor is starting for the first time; When the motor is starting for the first time, sequentially output drive signals with a preset duty cycle to each phase of the motor to perform current detection on each phase of the motor; When the motor is not starting for the first time, control the motor to operate normally.

8. A capacitor short-circuit detection device for a motor bootstrap circuit, characterized in that, A bootstrap circuit composed of bootstrap capacitors is correspondingly arranged for each phase on the high-voltage side of the motor. The device for detecting the short circuit of the capacitor in the motor bootstrap circuit includes: An output module, configured to sequentially output drive signals with a preset duty cycle to each phase of the motor to perform current detection on each phase of the motor. Among them, the drive signals of other phases except the current detection phase are empty; A sampling module, configured to sample the phase current data of the motor at each detection phase; A determination module, configured to determine the short-circuit detection result of the bootstrap circuit capacitor of the motor based on the magnitude relationship between the phase current data of different detection phases; the determining the short-circuit detection result of the bootstrap circuit capacitor of the motor based on the magnitude relationship between the phase current data of different detection phases includes: sorting the phase current data of different detection phases to determine the maximum phase current and the minimum phase current; determining whether the difference between the maximum phase current and the minimum phase current meets a preset difference condition; when the difference between the maximum phase current and the minimum phase current meets the preset difference condition, determining that the bootstrap circuit capacitor of the motor is short-circuited.

9. A capacitor short - circuit detection device for a motor bootstrap circuit, characterized in that, A bootstrap circuit composed of bootstrap capacitors is provided corresponding to each phase on the high-voltage side of the motor, and the motor bootstrap circuit capacitor short-circuit detection device includes: a motor controller, wherein the motor controller includes: A memory and a processor, the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to execute the method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a computer to execute the method according to any one of claims 1-7.

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