Voltage fault detection device and method for three-phase AC power supply, and motor controller

Abstract

The invention discloses a voltage fault detection device of a three-phase alternating current power supply, a motor controller and a voltage fault detection method thereof, and the device comprises a sampling unit which carries out the separation sampling of each phase of current in three-phase current from a rectification front end, and obtains the sampling voltage of each phase; the step-down unit is used for carrying out step-down on the sampling voltage of each phase to obtain the step-down voltage of each phase; the clamping unit is used for clamping the reduced voltage of each phase to obtain clamping voltage of each phase; the filtering unit is used for filtering the clamping voltage of each phase to obtain filtering voltage of each phase; and the control unit determines whether the phase voltage of each phase of the three-phase alternating-current power supply has a fault according to the filtering voltage of each phase so as to protect the three-phase alternating-current power supply and a load thereof. According to the scheme, the three-phase input current of the three-phase alternating-current power supply is separated and sampled from the rectification front end of the input side of the three-phase alternating-current power supply to obtain the sampling voltage, and fault detection is performed after voltage reduction, clamping and filtering, so that the accuracy of fault detection is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-phase AC power supply detection, and specifically relates to a voltage fault detection device of a three-phase AC power supply, a motor controller and a voltage fault detection method thereof, and more particularly to a phase voltage fault detection circuit of a three-phase AC power supply, a motor controller having the phase voltage fault detection circuit, and a phase voltage fault detection method of a three-phase AC power supply of the motor controller. Background Art

[0002] During the operation of a three-phase motor, one of the power lines often has no voltage, low voltage, or a power supply line disconnection. Taking the 380V power supply of the live wires L1, L2, and L3 of the three-phase AC power supply as an example, if the three-phase AC power supply input at the front end of the rectifier is missing one phase, it will become a two-phase operation, which is an abnormal working state. If the load is a three-phase resistor, there will be a situation where there is no current in one phase, and the voltage and current of the other two phases are normal; but if the load is a three-phase motor, it means single-phase operation, at this time the current will increase, exceeding the rated current of the motor, and the winding may be burned. At this time, it is necessary to detect the phase loss position of the three-phase AC power supply and limit the current to clamp the current, and at the same time report the abnormal state to the upper computer.

[0003] The main structure of the motor is generally unable to detect phase failure, so engineering often improves it from the hardware control or software algorithm. The phase voltage detection method used in the relevant scheme is to detect the voltage of the three-phase AC voltage before rectification by voltage division or transformer extraction to obtain the three-phase detection voltage, and then integrate the three-phase detection voltage into one for judgment, specifically within the rated voltage range, but the accuracy of the detection result of whether the phase voltage of the three-phase AC power supply is missing cannot be guaranteed.

[0004] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a voltage fault detection device for a three-phase AC power supply, a motor controller and a voltage fault detection method thereof, so as to solve the problem that the phase voltage detection method of the three-phase AC power supply used in the related scheme is to detect the voltage of the three-phase AC voltage by voltage division or transformer extraction before rectification to obtain the three-phase detection voltage, and then integrate the three-phase detection voltage into one path for judgment within the rated voltage range, but the accuracy of the detection result of whether the phase voltage of the three-phase AC power supply is missing a phase cannot be guaranteed, so as to achieve the effect of separating and sampling the three-phase input of the three-phase AC power supply through the rectifier front end on the input side of the three-phase AC power supply, and performing voltage reduction, clamping and filtering before performing fault detection, which is conducive to improving the accuracy of fault detection.

[0006] The present invention provides a voltage fault detection device for a three-phase AC power supply, wherein a three-phase common-mode inductor and a rectifier bridge are sequentially arranged on the rear side of the three-phase input terminal of the three-phase AC power supply inputted externally; the voltage fault detection device for the three-phase AC power supply comprises: a sampling unit, a voltage reduction unit, a clamping unit, a filtering unit, and a control unit; wherein the sampling unit is used to perform separate sampling of each phase current of the three-phase current inputted by the three-phase AC power supply between the three-phase common-mode inductor and the rectifier bridge to obtain a sampled voltage of each phase; the voltage reduction unit is used to perform voltage reduction on the sampled voltage of each phase to obtain a reduced voltage of each phase voltage; the clamping unit is used to clamp the stepped-down voltage of each phase according to the allowable voltage range of the control unit to obtain the clamping voltage of each phase; the filtering unit is used to filter the clamping voltage of each phase to obtain the filtered voltage of each phase; the control unit is used to determine whether the phase voltage of each phase of the three-phase AC power supply is faulty according to the filtered voltage of each phase; and, in the case of determining that the phase voltage of each phase of the three-phase AC power supply is faulty, initiate a reminder message of the phase voltage fault of each phase of the three-phase AC power supply, so as to protect the three-phase AC power supply and its load by controlling the three-phase AC power supply to stop power supply.

[0007] In some embodiments, the three-phase input end of the three-phase AC power supply includes: a U-phase input end, a V-phase input end, and a W-phase input end; wherein the sampling unit includes: a U-phase sampling module, a V-phase sampling module, and a W-phase sampling module; wherein the U-phase sampling module, the V-phase sampling module, and the W-phase sampling module are respectively used to separately sample the U-phase current, the V-phase current, and the W-phase current in the three-phase current input by the three-phase AC power supply, so as to obtain the U-phase sampling voltage, the V-phase sampling voltage, and the W-phase sampling voltage, respectively; the step-down unit includes: a U-phase step-down module, a V-phase step-down module, and a W-phase step-down module; wherein the U-phase step-down module, the V-phase step-down module, and the W-phase step-down module are respectively used to step down the U-phase sampling voltage, the V-phase sampling voltage, and the W-phase sampling voltage, respectively, so as to separate The clamping unit comprises: a U-phase clamping module, a V-phase clamping module and a W-phase clamping module; wherein the U-phase clamping module, the V-phase clamping module and the W-phase clamping module are respectively used to clamp the U-phase bucked voltage, the V-phase bucked voltage and the W-phase bucked voltage accordingly, so as to obtain the U-phase clamped voltage, the V-phase clamped voltage and the W-phase clamped voltage respectively; the filtering unit comprises: a U-phase filtering module, a V-phase filtering module and a W-phase filtering module; wherein the U-phase filtering module, the V-phase filtering module and the W-phase filtering module are respectively used to filter the U-phase clamped voltage, the V-phase clamped voltage and the W-phase clamped voltage accordingly, so as to obtain the U-phase filtered voltage, the V-phase filtered voltage and the W-phase filtered voltage respectively.

[0008] In some embodiments, the structures of the U-phase sampling module, the V-phase sampling module and the W-phase sampling module are the same; the U-phase sampling module includes: a first voltage-dividing resistor module, and a second voltage-dividing resistor module; wherein the U-phase input end of the three-phase input end is connected to the first connection end of the U-phase inductor in the three-phase common-mode inductor; the second connection end of the U-phase inductor is connected to the first connection end of the U-phase step-down module in the step-down unit after passing through the first voltage-dividing resistor module; the second connection end of the U-phase step-down module is grounded after passing through the second voltage-dividing resistor module.

[0009] In some embodiments, the first voltage-dividing resistor module includes: n sub-resistance modules, where n is a positive integer; in the first voltage-dividing resistor module, when n is greater than or equal to 2, the n sub-resistance modules are connected in series.

[0010] In some implementations, the U-phase sampling module further includes: a first capacitor module; the first capacitor module is connected in parallel to both ends of the second voltage-dividing resistor module.

[0011] In some embodiments, the structures of the U-phase buck module, the V-phase buck module and the W-phase buck module are the same; the U-phase buck module includes: a buck diode module; wherein the anode of the buck diode module serves as the first connection end of the U-phase buck module; the cathode of the buck diode module serves as the second connection end of the U-phase buck module; the second connection end of the U-phase buck module is connected to the clamping end of the U-phase clamping module in the clamping unit; the second connection end of the U-phase buck module is also connected to the first connection end of the U-phase filter module in the filter unit.

[0012] In some embodiments, the structures of the U-phase clamping module, the V-phase clamping module and the W-phase clamping module are the same; the U-phase clamping module includes: a clamping diode module; the clamping diode module includes: a first sub-diode module and a second sub-diode module; wherein the anode of the first sub-diode module is grounded, the cathode of the first sub-diode module is connected to the anode of the second sub-diode module, and the cathode of the second sub-diode module is used to connect to a preset DC power supply; the common end of the first sub-diode module and the second sub-diode module, as the clamping end of the U-phase clamping module, is connected to the second connection end of the U-phase buck module in the buck unit; wherein the preset DC power supply is used to provide a power supply voltage within the allowable voltage range of the control unit.

[0013] In some embodiments, the structures of the U-phase filter module, the V-phase filter module and the W-phase filter module are the same; the U-phase filter module includes: a filter resistor module and a filter capacitor module; wherein the second connection end of the U-phase step-down module in the step-down unit is grounded after passing through the filter resistor module and the filter capacitor module; the common end of the filter resistor module and the filter capacitor module serves as the output end of the U-phase filter module, and is used to output the filtered voltage of the U phase to the sampling end of the control unit.

[0014] Matching the above device, the present invention further provides a motor controller, comprising: the voltage fault detection device of the three-phase AC power supply described above.

[0015] Matching the above-mentioned motor controller, the present invention provides a voltage fault detection method for a motor controller on another aspect, comprising: by means of the sampling unit, separately sampling each phase current of the three-phase current input by the three-phase AC power supply from between the three-phase common-mode inductor and the rectifier bridge to obtain a sampled voltage of each phase; by means of the step-down unit, stepping down the sampled voltage of each phase to obtain a stepped-down voltage of each phase; by means of the clamping unit, clamping the stepped-down voltage of each phase according to the allowable voltage range of the control unit to obtain a clamped voltage of each phase; by means of the filtering unit, filtering the clamped voltage of each phase to obtain a filtered voltage of each phase; determining whether the phase voltage of each phase of the three-phase AC power supply is faulty according to the filtered voltage of each phase; and, in the case of determining that the phase voltage of each phase of the three-phase AC power supply is faulty, initiating a reminder message of the phase voltage fault of each phase of the three-phase AC power supply, so as to protect the three-phase AC power supply and its load by controlling the three-phase AC power supply to stop power supply.

[0016] Therefore, the scheme of the present invention is to set up a phase voltage fault detection circuit of a three-phase AC power supply mainly composed of a resistor voltage division sampling part, a diode voltage reduction part, a clamping diode part and an RC filtering part. When in use: using the resistor voltage division sampling part, between the three-phase common mode inductor and the rectifier bridge after the three-phase current input side of the three-phase AC power supply, each phase of the three-phase AC power supply is sampled separately to obtain the sampled voltage of each phase; using the diode voltage reduction part, the sampled voltage of each phase is reduced to obtain the reduced voltage of each phase; using the clamping diode In the tube part, the stepped-down voltage of each phase is clamped to obtain the clamped voltage of each phase; the clamped voltage of each phase is filtered by the RC filtering part to obtain the filtered voltage of each phase; through the control chip (such as MCU), it is judged whether each phase is faulty based on the filtered voltage of each phase, and the fault detection of the sampled voltage of each phase is realized; thus, the three-phase input of the three-phase AC power supply is separately sampled through the rectifier front end on the input side of the three-phase AC power supply, and the fault detection is performed after the voltage is stepped down, clamped and filtered, which is conducive to improving the accuracy of fault detection.

[0017] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of an embodiment of a voltage fault detection device for a three-phase AC power supply of the present invention;

[0020] Figure 2A structural block diagram of an embodiment of a phase voltage fault detection circuit for a three-phase AC power supply;

[0021] Figure 3 A schematic structural diagram of an embodiment of a phase voltage fault detection circuit for a three-phase AC power supply;

[0022] Figure 4 FIG. 4 is a flow chart of an embodiment of a method for detecting voltage failure of a motor controller of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] Considering that in the relevant scheme, the phase voltage detection method used is to detect the voltage of the three-phase AC voltage by voltage division or transformer extraction before rectification to obtain the three-phase detection voltage, and then integrate the three-phase detection voltage into one path for judgment within the rated voltage range. However, if this detection method takes into account undervoltage (such as the three-phase detection voltage is 0.7*V 额定电压 ) and overvoltage (such as the detection voltage of the three-phase is 1.45*V 额定电压 ), its threshold is difficult to reliably determine. Specifically, when taking into account the over-voltage and under-voltage conditions, the reduction in sampling voltage caused by the fluctuation of the three-phase line voltage may cause the chip to misjudge it as a phase loss abnormality. When the software control logic of phase loss and undervoltage is inconsistent, the control instruction cannot be accurately executed, resulting in the inability to guarantee the accuracy of the detection result of whether the phase voltage of the three-phase AC power supply is missing a phase.

[0025] Therefore, the scheme of the present invention proposes a voltage fault detection device for a three-phase AC power supply, specifically a phase voltage fault detection circuit for a three-phase AC power supply, which collects voltage signals from the live wires L1, L2, and L3 of the three-phase voltage input terminals of the three-phase AC power supply for judgment, and uses a low level to clamp the collected voltage signals to avoid high voltage shock before inputting them into the MCU. This detection method can take into account the full voltage range above and below the rated voltage, has higher reliability, and is conducive to improving the accuracy of the detection result of whether the phase voltage of the three-phase AC power supply is missing a phase.

[0026] In the related scheme, the three-phase detection voltage is integrated into one channel. Since the phase difference between the three-phase voltages is 120 degrees, the voltage of the common point to the ground will be approximately a constant after integration. If a single-phase phase is lost, the voltage of the common point cannot maintain a constant, so the phase loss abnormality can be detected. However, the disadvantages of this detection method are also obvious. For example, if the common point voltage is unbalanced due to a change in the frequency or amplitude of a certain phase, it will also be misjudged as a phase loss; and because the three phases are merged, it is impossible to determine whether multiple phases are lost at the same time and which specific phase has a phase loss. In addition, if the rectified voltage is sampled after rectification, the waveform after rectification is a wavy DC-like signal. When the power grid fluctuates and high and low voltages occur, if the input is detected by comparing fixed values ​​to see if the phase is lost, the over-voltage and under-voltage may be misreported as a phase loss; if the phase voltage amplitude is detected first, and then the threshold of the phase loss is calculated by software to compare the actual voltage value, the requirements for software design are high, and this method is also difficult to detect which specific phase has a phase loss.

[0027] Therefore, in the solution of the present invention, three phases are selected for sampling and detection before rectification, which can not only detect the sudden change of phase voltage more intuitively and simply, but also identify the specific phase-missing end. At the same time, if the software is improved, it can also be compatible with the over-voltage and under-voltage detection functions.

[0028] According to an embodiment of the present invention, a voltage fault detection device for a three-phase AC power supply is provided. Figure 1 The schematic diagram of the structure of an embodiment of the device of the present invention is shown in FIG. On the rear side of the three-phase input terminal of the three-phase AC power source inputted from the outside, three-phase common-mode inductors (such as Figure 3 The three-phase common mode inductor TR101 shown in FIG. 101 ), and a rectifier bridge (such as a rectifier bridge DB101 ); the voltage fault detection device for the three-phase AC power supply includes: a sampling unit (such as Figure 2 and Figure 3 The resistor voltage sampling part shown in the figure), the step-down unit (such as Figure 2 and Figure 3 The diode step-down section shown), the clamping unit (such as Figure 2 and Figure 3 The clamping diode part shown), the filtering unit (such as Figure 2 and Figure 3 RC filtering part shown), and a control unit (such as an MCU).

[0029] The sampling unit is used to perform separate sampling of each phase current of the three-phase current input by the three-phase AC power supply between the three-phase common mode inductor and the rectifier bridge to obtain a sampling voltage of each phase, so as to implement sampling of the phase voltage of each phase of the three-phase AC power supply. Separate sampling means that a separate resistance voltage division sampling module is used for separate sampling of each phase current, that is, three IO ports of the chip are occupied for signal detection.

[0030] The voltage reduction unit is used to reduce the voltage of the sampled voltage of each phase to obtain a reduced voltage of each phase.

[0031] The clamping unit is used to clamp the stepped-down voltage of each phase according to the allowable voltage range of the control unit to obtain the clamping voltage of each phase.

[0032] The filtering unit is used to filter the clamped voltage of each phase to obtain a filtered voltage of each phase, so as to process the sampled voltage of the phase voltage of each phase of the three-phase AC power supply.

[0033] The control unit is used to determine whether the phase voltage of each phase of the three-phase AC power supply is faulty according to the filtered voltage of each phase, so as to realize the fault detection of whether the phase voltage of each phase of the three-phase AC power supply is missing a phase; and, in the case of determining that the phase voltage of each phase of the three-phase AC power supply is faulty, initiate a reminder message of the phase voltage fault of each phase of the three-phase AC power supply, so as to protect the three-phase AC power supply and its load by controlling the three-phase AC power supply to stop supplying power, and realize the fault detection and protection processing of whether the phase voltage of each phase of the three-phase AC power supply is missing a phase. Among them, since the voltage fault detection device of the three-phase AC power supply itself does not have a power-off protection function, when the chip recognizes the phase-missing abnormality, the corresponding software design can report the corresponding fault to the host computer and issue a command to stop running or reduce speed to protect the motor. The operation of stopping the power supply needs to be completed manually by the operator after seeing the fault abnormality displayed by the host computer.

[0034] The solution of the present invention provides a phase voltage fault detection circuit for a three-phase AC power supply, which uses live wires L1, L2, and L3 from the three-phase voltage input end of the three-phase AC power supply to collect voltages for discrimination, and uses a low level to clamp the collected signal to avoid high voltage shock before inputting it into the MCU. The phase voltage fault detection circuit of the three-phase AC power supply can take into account the full voltage range above the rated voltage and below the rated voltage, and has higher reliability. Thus, the problem that the three-phase motor cannot accurately judge the phase loss in the over-voltage or under-voltage situation because the three-phase detection voltage is integrated into one way for discrimination is solved, which is conducive to improving the accuracy of the detection result of whether the phase voltage of the three-phase AC power supply is missing.

[0035] In some embodiments, the three-phase input terminal of the three-phase AC power supply includes: a U-phase input terminal (such as the live wire L1), a V-phase input terminal (such as the live wire L2), and a W-phase input terminal (such as the live wire L3). Figure 3 FIG. 1 is a schematic diagram of a structure of an embodiment of a phase voltage fault detection circuit for a three-phase AC power supply. Figure 3 In the example shown, TR101 is a three-phase common-mode inductor, DB101 is a rectifier bridge; the voltage between the terminal V+ and the terminal V- at the output end of the rectifier bridge is about 540V, the voltage between the terminal V+ and the terminal V- is the normal output voltage, and the corresponding DC circuit is connected; the CLAMPING signal is the maximum allowable voltage signal, and PHASELOSS_L1, L2 and L3 are sampling signals input to the detection chip (such as MCU).

[0036] The sampling unit includes: a U-phase sampling module, a V-phase sampling module and a W-phase sampling module. The U-phase sampling module, the V-phase sampling module and the W-phase sampling module are respectively used to separately sample the U-phase current, the V-phase current and the W-phase current of the three-phase current input by the three-phase AC power supply, so as to obtain the sampling voltage of the U-phase, the sampling voltage of the V-phase and the sampling voltage of the W-phase respectively.

[0037] The step-down unit includes: a U-phase step-down module, a V-phase step-down module and a W-phase step-down module; wherein the U-phase step-down module, the V-phase step-down module and the W-phase step-down module are respectively used to correspondingly step down the sampled voltage of the U-phase, the sampled voltage of the V-phase and the sampled voltage of the W-phase to obtain the step-down voltage of the U-phase, the step-down voltage of the V-phase and the step-down voltage of the W-phase respectively.

[0038] The clamping unit comprises: a U-phase clamping module, a V-phase clamping module and a W-phase clamping module; wherein the U-phase clamping module, the V-phase clamping module and the W-phase clamping module are respectively used to clamp the step-down voltage of the U-phase, the step-down voltage of the V-phase and the step-down voltage of the W-phase accordingly, so as to obtain the clamping voltage of the U-phase, the clamping voltage of the V-phase and the clamping voltage of the W-phase respectively.

[0039] The filtering unit includes: a U-phase filtering module, a V-phase filtering module and a W-phase filtering module; wherein the U-phase filtering module, the V-phase filtering module and the W-phase filtering module are respectively used to filter the clamping voltage of the U-phase, the clamping voltage of the V-phase and the clamping voltage of the W-phase correspondingly to obtain the filtering voltage of the U-phase, the filtering voltage of the V-phase and the filtering voltage of the W-phase respectively.

[0040] Figure 2 FIG. 1 is a structural block diagram of an embodiment of a phase voltage fault detection circuit for a three-phase AC power supply. Figure 2As shown in the figure, the phase voltage fault detection circuit of the three-phase AC power supply includes: a resistor voltage division sampling part, a diode voltage reduction part, a clamping diode voltage range control part, and an RC filtering part. The three-phase input voltage of the three-phase AC power supply is sampled and detected separately. The three-phase input voltage is divided by the resistor voltage division sampling part and then reduced by the diode voltage reduction part. Then the clamping diode voltage range control part controls the voltage. Finally, it is filtered by the RC filtering part and then enters the MCU to judge the voltage state of each sampling circuit and output the phase loss abnormality to the upper computer.

[0041] In the scheme of the present invention, the three-phase input of the three-phase AC power supply is sampled separately, and the sampling is not rectified, which makes the phase loss judgment under overvoltage and undervoltage conditions more accurate. In the scheme of the present invention, the voltage divider resistor of the resistor voltage divider sampling part is used in conjunction with the step-down diode of the diode step-down part and the clamping diode of the clamping diode part to ensure safety, simple devices and accurate sampling. In addition, in the scheme of the present invention, no optical coupler device is used for transmission, the high-frequency response is better, and there is a better linear relationship between the sampled input and output, which is conducive to improving the sampling accuracy.

[0042] In some embodiments, the U-phase sampling module, the V-phase sampling module and the W-phase sampling module have the same structure; the U-phase sampling module includes: a first voltage-dividing resistor module (such as Figure 3 The resistors R1, R2, R3 and R4 shown in FIG. 1 , and the second voltage-dividing resistor module (such as Figure 3 Resistor R15 shown).

[0043] Among them, the U-phase input end (such as the live wire L1) among the three-phase input ends is connected to the first connection end of the U-phase inductor among the three-phase common-mode inductor; the second connection end of the U-phase inductor is connected to the first connection end of the U-phase step-down module in the step-down unit after passing through the first voltage-dividing resistor module; the second connection end of the U-phase step-down module is grounded after passing through the second voltage-dividing resistor module; the second connection end of the U-phase step-down module is also respectively connected to the U-phase clamping module in the clamping unit and the U-phase filtering module in the filtering unit.

[0044] In the scheme of the present invention, the sampling method selects the method of using the resistor voltage sampling part to perform resistor voltage division and the diode voltage reduction part to perform diode voltage reduction. First of all, the devices used in this method are simple and will not be greatly affected. When the environmental factors change over a large range, the voltage output can be relatively stable; secondly, a large resistor is used in series in the resistor voltage division sampling part, and finally the clamping diode part is used to control the sampling signal to the voltage that the control chip pin can accept; after passing through the voltage reduction diode part, due to the characteristics of the diode itself, there will be a voltage reduction effect of about 0.75V, and some reverse noise can be filtered out. Considering the high voltage compatibility, the output voltage after passing through the diode in the diode voltage reduction part is generally set according to 1 / 2 of the maximum acceptable voltage, and the voltage reduction ratio of the voltage-dividing resistor is set after adding the voltage drop of the diode in the diode voltage reduction part (such as the voltage reduction ratio of resistors R1, R2, R3 and R4, and resistor R15). Among them, the purpose of setting the voltage-dividing ratio of the voltage-dividing resistor is to convert the high voltage signal sampled from the three-phase input into a voltage that the chip pin can accept. The specific output voltage should be calculated based on the voltage that the chip pin can withstand, plus the ratio of the voltage after the diode is stepped down to the phase voltage, so the step-down ratio needs to be set; and considering the fluctuation of the power grid, sufficient margin needs to be left. Therefore, when selecting the voltage divider resistor, it is necessary to use a resistor with a larger resistance value and a larger package to prevent large current from damaging the resistor and the chip.

[0045] In some embodiments, the first voltage-dividing resistor module includes: n sub-resistance modules, where n is a positive integer; in the first voltage-dividing resistor module, when n is greater than or equal to 2, the n sub-resistance modules are connected in series.

[0046] In the scheme of the present invention, a large resistor is used in series for voltage division in the resistor voltage division sampling part. On the one hand, the sampled voltage is a high voltage of 380V, and the voltage allowed by the pins of the detection chip is mostly only a few volts. The input current also needs to be controlled between tens of milliamperes and hundreds of milliamperes. In addition, the forward internal resistance of the series diode is very small, and excessive current will cause the diode to be broken down. Therefore, it is necessary to select a large resistor or a resistor with a large package for voltage division, or in the case of Figure 3 In the example shown, multiple larger package resistors are selected to be connected in series to step down the voltage step by step, and finally the clamping diode part is used to control the sampling signal to a voltage that the control chip pin can accept; after passing through the step-down diode part, due to the characteristics of the diode itself, there will be a voltage reduction effect of about 0.75V, and some reverse noise can be filtered out.

[0047] In some implementations, the U-phase sampling module further includes: a first capacitor module (such as Figure 3 The capacitor C3 shown); the first capacitor module is connected in parallel to both ends of the second voltage-dividing resistor module.

[0048] In the scheme of the present invention, the three-phase input voltage of the three-phase AC power supply is sampled and detected separately, and the voltage is divided by a resistor voltage-dividing sampling part (such as simple devices such as resistors and capacitors) and then stepped down by a diode voltage-stepping part, and then the voltage is controlled by a clamping diode voltage range control part, and finally filtered by an RC filtering part before entering the MCU, judging the voltage state of each sampling circuit and outputting the phase-loss abnormality to the upper computer. This detection method can not only more accurately judge the phase-loss state in the over-voltage and under-voltage state, but also use the sampling circuit to detect and judge the overvoltage and undervoltage of the input voltage at the same time by changing the software part, and greatly reduce the possibility of the sampling signal impact damaging the chip.

[0049] When a phase is missing, taking the U phase as an example, the voltage is divided and sampled by resistors R1, R2, R3, and R4, and then reduced by a diode, and a voltage value within the rated voltage range of the control chip pin is output through resistor R15; considering the voltage fluctuation of the power grid, a clamping diode and an RC filter circuit are added before the sampling signal is connected to the control chip to ensure that the control chip will not be damaged due to excessive voltage, and at the same time ensure the stability of the sampling signal. Among them, the pull-down resistor (such as resistor R15) is set after the diode (such as diode DB1). The advantages of this setting are: first, the forward movement of the diode reduces the current flowing through the pull-down resistor, the power consumption of the pull-down resistor is low, and the heat loss is reduced. Secondly, if the diode is placed after the pull-down resistor, the effect of the diode will be affected by the resistor; if the resistance value of the pull-down resistor is selected to be small, the voltage after the diode may be unstable, and due to the load effect, the pull-down resistor will share part of the voltage; after the diode is moved forward, in addition to eliminating the load, the pull-down resistor can also help stabilize the voltage. In addition, the diode cannot be too far forward, because the resistor before the diode plays a role in current limiting.

[0050] Since the sampling circuit detects the three phases separately instead of rectifying the three phases into a quasi-DC signal for detection, it is possible to identify the missing U phase separately. Another advantage of three-phase separate detection is that if the effective value of the modulated quasi-DC waveform is high due to grid voltage fluctuations, such as overvoltage, if the U phase is missing at this time, the voltage at the corresponding position of the U phase after modulation is reduced, but it may still be within the "normal" range of detection, resulting in an inability to accurately determine whether the phase is missing; similarly, if it is undervoltage, the effective value of the normal waveform after modulation is low, which may lead to a misjudgment of the missing phase. Therefore, in the scheme of the present invention, three-phase sampling is selected, taking into account the sampling of missing phases under and overvoltage, so that the control chip can make the most accurate judgment; in addition, by changing the software, the sampling circuit can simultaneously realize the function of judging the missing phase and over- and under-voltage, which has certain expansibility. For example: Generally, for over- and under-voltage sampling, most of the sampling will be selected at the bus voltage, because it has been rectified and filtered, it is a more stable DC signal, and the software is also easier to distinguish. The circuit provided by the solution of the present invention can also judge overvoltage and undervoltage, because the circuit itself samples the power supply value of the three phases in the process of sampling the phase loss, and before comparing the three-phase voltage values, in order to avoid sudden power failure, it will first judge the voltage of each phase before judging the phase loss, and only when each phase voltage is higher than a certain set value will the phase loss identification be performed to prevent false triggering. Among them, the process of judging that the phase voltage is higher than a certain set value can use the software logic for judging overvoltage and undervoltage.

[0051] In some embodiments, the U-phase buck module, the V-phase buck module and the W-phase buck module have the same structure; the U-phase buck module includes: a buck diode module (such as Figure 3 Diode DB1 shown).

[0052] The anode of the buck diode module serves as the first connection end of the U-phase buck module; the cathode of the buck diode module serves as the second connection end of the U-phase buck module. The second connection end of the U-phase buck module is connected to the clamping end of the U-phase clamping module in the clamping unit; the second connection end of the U-phase buck module is also connected to the first connection end of the U-phase filter module in the filter unit; the second connection end of the U-phase filter module is connected to the sampling end of the control unit.

[0053] In the scheme of the present invention, during the operation of the three-phase motor, voltage division sampling is performed after the three-phase current passes through the three-phase common-mode inductor TR101, and the diode of the diode step-down part is used to step down the voltage. Compared with related schemes, the scheme of the present invention has simple configuration, simple devices, high reliability, and stable sampling, which can avoid the chip's misjudgment of phase loss caused by sampling voltage fluctuations caused by environmental factors to a greater extent.

[0054] In some embodiments, the U-phase clamp module, the V-phase clamp module and the W-phase clamp module have the same structure; the U-phase clamp module includes: a clamp diode module (such as Figure 3 The clamping diode DB4 shown in the figure); the clamping diode module includes: a first sub-diode module and a second sub-diode module.

[0055] Among them, the anode of the first sub-diode module is grounded, the cathode of the first sub-diode module is connected to the anode of the second sub-diode module, and the cathode of the second sub-diode module is used to connect to a preset DC power supply; the common end of the first sub-diode module and the second sub-diode module serves as the clamping end of the U-phase clamping module and is connected to the second connection end of the U-phase buck module in the buck unit; wherein the preset DC power supply is used to provide a power supply voltage within the allowable voltage range of the control unit.

[0056] In the scheme of the present invention, the signal needs to be processed before the signal input enters the control chip. First, the voltage divider resistor connected to the ground (such as the resistor R15 of the U phase) will act as a pull-down resistor. When there is no input to the power supply part, the level of the pin is pulled to the ground, which can prevent interference during power failure from damaging the control chip. Next, a clamping diode is used. The cathode of the clamping diode is clamped with the maximum level allowed by the control chip, and the anode of the clamping diode is grounded. When the input voltage is between 0 and the maximum allowable voltage of the control chip, it can be input normally. When the voltage fluctuates, if it is greater than the maximum allowable voltage, the diode between the input signal and the maximum allowable voltage is turned on, and the level is pulled down to the maximum allowable voltage; if a reverse voltage occurs, the diode between the input signal and the ground is turned on, and the input voltage is pulled up to 0. This design ensures the fluctuation range of the input voltage and prevents the possibility of damage to the control chip by the peak voltage shock.

[0057] In some embodiments, the U-phase filter module, the V-phase filter module and the W-phase filter module have the same structure; the U-phase filter module includes: a filter resistor module (such as Figure 3 The resistor R16 shown), and the filter capacitor module (such as Figure 3 The capacitor C6 shown in the figure). The second connection end of the U-phase buck module in the buck unit is grounded after passing through the filter resistor module and the filter capacitor module; the common end of the filter resistor module and the filter capacitor module serves as the output end of the U-phase filter module, and is used to output the U-phase filtered voltage to the sampling end of the control unit.

[0058] In the solution of the present invention, an RC circuit is finally used to access the control chip. This design provides the final filtering for the control chip input, thereby ensuring the stability of the input signal.

[0059] Specifically, Figure 3 As shown, the resistor voltage-dividing sampling part includes: resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7, resistor R8, resistor R9, resistor R10, resistor R11, and resistor R12; the resistor voltage-dividing sampling part also includes: resistor R13, resistor R14, resistor R15, capacitor C1, capacitor C2, and capacitor C3. The diode step-down part includes: diode DB1, diode DB2, and diode DB3. The RC filtering part includes: resistor R16, resistor R17, resistor R18, capacitor C4, capacitor C5, and capacitor C6. The clamping diode part includes: diode group DB4, diode group DB5, and diode group DB6. In each diode group of diode group DB4, diode group DB5, and diode group DB6, each diode includes a first diode and a second diode, the anode of the first diode is grounded, the cathode of the first diode is connected to the anode of the second diode, and the cathode of the second diode is connected to the CLAMPING terminal; the common end of the first diode and the second diode is the clamping end of the GIA diode group. The live wires L1, L2 and L3 at the three-phase voltage input end are output to the terminals V+ and V- after passing through the three-phase common-mode inductor TR101 and the rectifier bridge DB101.

[0060] Among them, the live wire L1 of the three-phase current input terminal is connected to the anode of the diode DB1 after passing through the first phase common mode inductor in the three-phase common mode inductor TR101, the resistor R1, the resistor R2, the resistor R3 and the resistor R4 connected in series. The cathode of the diode DB1 is connected to the clamping end of the diode group BD4. The cathode of the diode DB1 is also connected to the ground after passing through the parallel resistor R15 and the capacitor C3. The cathode of the diode DB1 is also connected to the ground after passing through the resistor R16 and the capacitor C6, and the common end of the resistor R16 and the capacitor C6 is connected to the terminal PHASELOSS_L1.

[0061] The live wire L2 of the three-phase current input terminal is connected to the anode of the diode DB2 after passing through the second phase common mode inductor in the three-phase common mode inductor TR101, the resistor R5, the resistor R6, the resistor R7 and the resistor R8 connected in series. The cathode of the diode DB2 is connected to the clamping end of the diode group BD5. The cathode of the diode DB2 is also connected to the ground after passing through the parallel resistor R14 and the capacitor C2. The cathode of the diode DB2 is also connected to the ground after passing through the resistor R17 and the capacitor C5, and the common end of the resistor R17 and the capacitor C5 is connected to the terminal PHASELOSS_L2.

[0062] The live wire L3 of the three-phase current input terminal is connected to the anode of the diode DB3 after passing through the third phase common mode inductor in the three-phase common mode inductor TR101, the resistor R9, the resistor R10, the resistor R11 and the resistor R12 connected in series. The cathode of the diode DB3 is connected to the clamping end of the diode group BD6. The cathode of the diode DB3 is also connected to the ground after passing through the parallel resistor R13 and the capacitor C1. The cathode of the diode DB3 is also connected to the ground after passing through the resistor R18 and the capacitor C4, and the common end of the resistor R18 and the capacitor C4 is connected to the terminal PHASELOSS_L3.

[0063] exist Figure 3 In the example shown, the three-phase input voltage of the three-phase AC power supply is selected to be sampled after passing through the three-phase common-mode inductor TR101 in the motor controller and before the rectifier bridge DB101 rectifies. After passing through the three-phase common-mode inductor TR101, the common-mode signal can be blocked, which can improve the reliability and stability of the signal; after being rectified by the rectifier bridge DB101, the three-phase 380V is rectified into a DC voltage of about 540V. Although sampling at this time can reduce the occupation of the period and chip detection pins, when the voltage fluctuates, under high and low voltage conditions, the voltage fluctuation range after the three-phase integration is large, and it is impossible to accurately distinguish whether the source of the sampled voltage fluctuation is the fluctuation of the three-phase voltage or the single-phase phase loss, so it is difficult to accurately determine the phase loss information. Therefore, after the three-phase common-mode inductor TR101 is input into the live wire L1, live wire L2 and live wire L3 of the three-phase AC power supply, the three phases are sampled at the same time before the rectifier bridge DB101, and each phase is detected separately to ensure that the judgment of the phase loss will not be affected by the voltage fluctuation.

[0064] In the scheme of the present invention, voltage detection is performed by sampling phase voltage using a voltage divider circuit; a reference voltage and a clamping diode are used to control the voltage range input to the control chip to avoid chip damage; and a resistor voltage divider is used to sample the phase voltage for comparison. Compared with the scheme of the related scheme, the components are simpler, and the input phase loss information can be accurately judged in a larger voltage range. By changing the software, more functions such as voltage detection can be compatible, which solves the problem that the three-phase motor cannot accurately judge the phase loss in over-voltage and under-voltage conditions due to the three-phase detection voltage being integrated into one path for judgment, and the problem that the sampling signal impact damages the chip. By sampling the three-phase input of the three-phase AC power supply separately, the judgment of phase loss in over-voltage and under-voltage conditions is more accurate, which is suitable for more occasions. By changing the software part, more functions besides phase loss detection can be realized.

[0065] The technical solution of the present invention is adopted, by setting a phase voltage fault detection circuit of a three-phase AC power supply mainly composed of a resistor voltage-dividing sampling part, a diode voltage-reducing part, a clamping diode part and an RC filtering part. When in use: using the resistor voltage-dividing sampling part, sampling is performed separately for each phase of the three-phase AC power supply between the three-phase common-mode inductor and the rectifier bridge after the three-phase current input side of the three-phase AC power supply to obtain the sampled voltage of each phase; using the diode voltage-reducing part, the sampling voltage of each phase is reduced to obtain the reduced voltage of each phase; using the clamping diode The pole tube part clamps the stepped-down voltage of each phase to obtain the clamped voltage of each phase; the RC filtering part filters the clamped voltage of each phase to obtain the filtered voltage of each phase; through the control chip (such as MCU), it is judged whether each phase is faulty based on the filtered voltage of each phase, and the fault detection of the sampled voltage of each phase is realized; thus, the three-phase input of the three-phase AC power supply is separately sampled through the rectifier front end on the input side of the three-phase AC power supply, and the fault detection is performed after the voltage is stepped down, clamped and filtered, which is conducive to improving the accuracy of fault detection.

[0066] According to an embodiment of the present invention, a motor controller corresponding to the voltage fault detection device of the three-phase AC power supply is also provided. The motor controller may include: the voltage fault detection device of the three-phase AC power supply described above.

[0067] Since the processing and functions implemented by the motor controller of this embodiment basically correspond to the embodiments, principles and examples of the device, for the details not described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0068] According to an embodiment of the present invention, a voltage fault detection method of a motor controller corresponding to the motor controller is also provided, such as Figure 4 The flowchart of an embodiment of the method of the present invention is shown in FIG. The voltage fault detection method of the motor controller may include: steps S110 to S150.

[0069] At step S110, the sampling unit is used to separately sample each phase current of the three-phase current input by the three-phase AC power supply between the three-phase common-mode inductor and the rectifier bridge to obtain a sampling voltage of each phase, so as to implement sampling of the phase voltage of each phase of the three-phase AC power supply.

[0070] The sampling unit includes: a U-phase sampling module, a V-phase sampling module and a W-phase sampling module. The U-phase sampling module, the V-phase sampling module and the W-phase sampling module are respectively used to separately sample the U-phase current, the V-phase current and the W-phase current of the three-phase current input by the three-phase AC power supply, so as to obtain the sampling voltage of the U-phase, the sampling voltage of the V-phase and the sampling voltage of the W-phase respectively.

[0071] In some embodiments, the U-phase sampling module, the V-phase sampling module and the W-phase sampling module have the same structure; the U-phase sampling module includes: a first voltage-dividing resistor module (such as Figure 3 The resistors R1, R2, R3 and R4 shown in FIG. 1 , and the second voltage-dividing resistor module (such as Figure 3 Resistor R15 shown).

[0072] Among them, the U-phase input end (such as the live wire L1) among the three-phase input ends is connected to the first connection end of the U-phase inductor among the three-phase common-mode inductor; the second connection end of the U-phase inductor is connected to the first connection end of the U-phase step-down module in the step-down unit after passing through the first voltage-dividing resistor module; the second connection end of the U-phase step-down module is grounded after passing through the second voltage-dividing resistor module; the second connection end of the U-phase step-down module is also respectively connected to the U-phase clamping module in the clamping unit and the U-phase filtering module in the filtering unit.

[0073] In the scheme of the present invention, the sampling method selects the method of using the resistor voltage sampling part for resistor voltage division and the diode voltage reduction part for diode voltage reduction combination. First of all, the devices used in this method are simple and will not be greatly affected. When the environmental factors change over a large range, the voltage output can be relatively stable; secondly, a large resistor is used in series for voltage division in the resistor voltage division sampling part, and finally the clamping diode part is used to control the sampling signal to the voltage that the control chip pin can accept; after passing through the voltage reduction diode part, due to the characteristics of the diode itself, there will be a voltage reduction effect of about 0.75V, and part of the reverse noise can be filtered out. Considering the compatibility with high voltage, the output voltage after passing through the diode in the diode voltage reduction part is generally set according to 1 / 2 of the maximum acceptable voltage, and the voltage reduction ratio of the voltage-dividing resistor is set after adding the voltage drop of the diode in the diode voltage reduction part (such as the voltage reduction ratio of resistor R1, resistor R2, resistor R3 and resistor R4, and resistor R15).

[0074] In some embodiments, the first voltage-dividing resistor module includes: n sub-resistance modules, where n is a positive integer; in the first voltage-dividing resistor module, when n is greater than or equal to 2, the n sub-resistance modules are connected in series.

[0075] In the scheme of the present invention, a large resistor is used in series for voltage division in the resistor voltage division sampling part. On the one hand, the sampled voltage is a high voltage of 380V, and the voltage allowed by the pins of the detection chip is mostly only a few volts. The input current also needs to be controlled between tens of milliamperes and hundreds of milliamperes. In addition, the forward internal resistance of the series diode is very small, and excessive current will cause the diode to be broken down. Therefore, it is necessary to select a large resistor or a resistor with a large package for voltage division, or in the case of Figure 3 In the example shown, multiple larger package resistors are selected to be connected in series to step down the voltage step by step, and finally the clamping diode part is used to control the sampling signal to a voltage that the control chip pin can accept; after passing through the step-down diode part, due to the characteristics of the diode itself, there will be a voltage reduction effect of about 0.75V, and some reverse noise can be filtered out.

[0076] In some implementations, the U-phase sampling module further includes: a first capacitor module (such as Figure 3 The capacitor C3 shown); the first capacitor module is connected in parallel to both ends of the second voltage-dividing resistor module.

[0077] In the scheme of the present invention, the three-phase input voltage of the three-phase AC power supply is sampled and detected separately, and the voltage is divided by a resistor voltage-dividing sampling part (such as simple devices such as resistors and capacitors) and then stepped down by a diode voltage-stepping part, and then the voltage is controlled by a clamping diode voltage range control part, and finally filtered by an RC filtering part before entering the MCU, judging the voltage state of each sampling circuit and outputting the phase-loss abnormality to the upper computer. This detection method can not only more accurately judge the phase-loss state in the over-voltage and under-voltage state, but also use the sampling circuit to detect and judge the overvoltage and undervoltage of the input voltage at the same time by changing the software part, and greatly reduce the possibility of the sampling signal impact damaging the chip.

[0078] In step S120, the voltage reduction unit reduces the voltage of the sampled voltage of each phase to obtain a reduced voltage of each phase.

[0079] Among them, the buck unit includes: a U-phase buck module, a V-phase buck module and a W-phase buck module; wherein the U-phase buck module, the V-phase buck module and the W-phase buck module are respectively used to correspondingly buck the sampled voltage of the U phase, the sampled voltage of the V phase and the sampled voltage of the W phase to obtain the bucked voltage of the U phase, the bucked voltage of the V phase and the bucked voltage of the W phase respectively.

[0080] In some embodiments, the U-phase buck module, the V-phase buck module and the W-phase buck module have the same structure; the U-phase buck module includes: a buck diode module (such as Figure 3 Diode DB1 shown).

[0081] The anode of the buck diode module serves as the first connection end of the U-phase buck module; the cathode of the buck diode module serves as the second connection end of the U-phase buck module. The second connection end of the U-phase buck module is connected to the clamping end of the U-phase clamping module in the clamping unit; the second connection end of the U-phase buck module is also connected to the first connection end of the U-phase filter module in the filter unit; the second connection end of the U-phase filter module is connected to the sampling end of the control unit.

[0082] In the scheme of the present invention, during the operation of the three-phase motor, voltage division sampling is performed after the three-phase current passes through the three-phase common-mode inductor TR101, and the diode of the diode step-down part is used to step down the voltage. Compared with related schemes, the scheme of the present invention has simple configuration, simple devices, high reliability, and stable sampling, which can avoid the chip's misjudgment of phase loss caused by sampling voltage fluctuations caused by environmental factors to a greater extent.

[0083] In step S130, the clamping unit clamps the stepped-down voltage of each phase according to the allowable voltage range of the control unit to obtain the clamping voltage of each phase.

[0084] Wherein, the clamping unit comprises: a U-phase clamping module, a V-phase clamping module and a W-phase clamping module; wherein, the U-phase clamping module, the V-phase clamping module and the W-phase clamping module are respectively used to clamp the step-down voltage of the U-phase, the step-down voltage of the V-phase and the step-down voltage of the W-phase accordingly, so as to obtain the clamping voltage of the U-phase, the clamping voltage of the V-phase and the clamping voltage of the W-phase respectively.

[0085] In some embodiments, the U-phase clamp module, the V-phase clamp module and the W-phase clamp module have the same structure; the U-phase clamp module includes: a clamp diode module (such as Figure 3 The clamping diode DB4 shown in the figure); the clamping diode module includes: a first sub-diode module and a second sub-diode module.

[0086] Among them, the anode of the first sub-diode module is grounded, the cathode of the first sub-diode module is connected to the anode of the second sub-diode module, and the cathode of the second sub-diode module is used to connect to a preset DC power supply; the common end of the first sub-diode module and the second sub-diode module serves as the clamping end of the U-phase clamping module and is connected to the second connection end of the U-phase buck module in the buck unit; wherein the preset DC power supply is used to provide a power supply voltage within the allowable voltage range of the control unit.

[0087] In the scheme of the present invention, the signal needs to be processed before the signal input enters the control chip. First, the voltage divider resistor connected to the ground (such as the resistor R15 of the U phase) will act as a pull-down resistor. When there is no input to the power supply part, the level of the pin is pulled to the ground, which can prevent interference during power failure from damaging the control chip. Next, a clamping diode is used. The cathode of the clamping diode is clamped with the maximum level allowed by the control chip, and the anode of the clamping diode is grounded. When the input voltage is between 0 and the maximum allowable voltage of the control chip, it can be input normally. When the voltage fluctuates, if it is greater than the maximum allowable voltage, the diode between the input signal and the maximum allowable voltage is turned on, and the level is pulled down to the maximum allowable voltage; if a reverse voltage occurs, the diode between the input signal and the ground is turned on, and the input voltage is pulled up to 0. This design ensures the fluctuation range of the input voltage and prevents the possibility of damage to the control chip by the peak voltage shock.

[0088] At step S140, the clamped voltage of each phase is filtered by the filtering unit to obtain a filtered voltage of each phase, so as to process the sampled voltage of the phase voltage of each phase of the three-phase AC power supply.

[0089] Wherein, the filtering unit includes: a U-phase filtering module, a V-phase filtering module and a W-phase filtering module; wherein the U-phase filtering module, the V-phase filtering module and the W-phase filtering module are respectively used to filter the clamping voltage of the U-phase, the clamping voltage of the V-phase and the clamping voltage of the W-phase accordingly to obtain the filtering voltage of the U-phase, the filtering voltage of the V-phase and the filtering voltage of the W-phase respectively.

[0090] In some embodiments, the U-phase filter module, the V-phase filter module and the W-phase filter module have the same structure; the U-phase filter module includes: a filter resistor module (such as Figure 3 The resistor R16 shown), and the filter capacitor module (such as Figure 3 The capacitor C6 shown in the figure). The second connection end of the U-phase buck module in the buck unit is grounded after passing through the filter resistor module and the filter capacitor module; the common end of the filter resistor module and the filter capacitor module serves as the output end of the U-phase filter module, and is used to output the U-phase filtered voltage to the sampling end of the control unit.

[0091] In the solution of the present invention, an RC circuit is finally used to access the control chip. This design provides the final filtering for the control chip input, thereby ensuring the stability of the input signal.

[0092] At step S150, it is determined whether the phase voltage of each phase of the three-phase AC power supply is faulty based on the filtered voltage of each phase, so as to realize the fault detection of whether the phase voltage of each phase of the three-phase AC power supply is missing a phase; and, in the case of determining that the phase voltage of each phase of the three-phase AC power supply is faulty, a reminder message of the phase voltage fault of each phase of the three-phase AC power supply is initiated, so as to protect the three-phase AC power supply and its load by controlling the three-phase AC power supply to stop power supply, thereby realizing the fault detection and protection processing of whether the phase voltage of each phase of the three-phase AC power supply is missing a phase.

[0093] The solution of the present invention adopts the live wires L1, L2, and L3 from the three-phase voltage input end of the three-phase AC power supply to collect voltages for discrimination, and uses a low level to clamp the collected signal to avoid high voltage shock before inputting it into the MCU. The phase voltage fault detection circuit of the three-phase AC power supply can take into account the full voltage range of higher than the rated voltage and lower than the rated voltage, and has higher reliability. Thus, the problem that the three-phase motor cannot accurately judge the phase loss in the over-voltage or under-voltage situation because the three-phase detection voltage is integrated into one way for discrimination is solved, which is conducive to improving the accuracy of the detection result of whether the phase voltage of the three-phase AC power supply is missing.

[0094] Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned motor controller, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0095] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0096] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A voltage fault detection device for a three-phase AC power supply, characterized in that: A three-phase common-mode inductor and a rectifier bridge are sequentially arranged on the rear side of the three-phase input terminal of the three-phase AC power supply inputted from the outside; the voltage fault detection device of the three-phase AC power supply comprises: a sampling unit, a step-down unit, a clamping unit, a filtering unit, and a control unit; wherein, The sampling unit is used to separately sample each phase current of the three-phase current input by the three-phase AC power supply between the three-phase common mode inductor and the rectifier bridge to obtain a sampling voltage of each phase; The step-down unit is used to step down the sampled voltage of each phase to obtain a stepped-down voltage of each phase; The clamping unit is used to clamp the stepped-down voltage of each phase according to the allowable voltage range of the control unit to obtain the clamping voltage of each phase; The filtering unit is used to filter the clamping voltage of each phase to obtain a filtered voltage of each phase; The control unit is used to determine whether the phase voltage of each phase of the three-phase AC power supply is faulty based on the filtered voltage of each phase; and, when it is determined that the phase voltage of each phase of the three-phase AC power supply is faulty, initiate a reminder message of the phase voltage fault of each phase of the three-phase AC power supply, so as to protect the three-phase AC power supply and its load by controlling the three-phase AC power supply to stop power supply.

2. The voltage fault detection device for a three-phase AC power supply according to claim 1, characterized in that: The three-phase input terminal of the three-phase AC power supply includes: a U-phase input terminal, a V-phase input terminal, and a W-phase input terminal; in, The sampling unit comprises: a U-phase sampling module, a V-phase sampling module and a W-phase sampling module; wherein the U-phase sampling module, the V-phase sampling module and the W-phase sampling module are respectively used to separately sample the U-phase current, the V-phase current and the W-phase current of the three-phase current input by the three-phase AC power supply, so as to obtain the sampling voltage of the U-phase, the sampling voltage of the V-phase and the sampling voltage of the W-phase respectively; The step-down unit comprises: a U-phase step-down module, a V-phase step-down module and a W-phase step-down module; wherein the U-phase step-down module, the V-phase step-down module and the W-phase step-down module are respectively used to step down the sampled voltage of the U-phase, the sampled voltage of the V-phase and the sampled voltage of the W-phase, so as to obtain the step-down voltage of the U-phase, the step-down voltage of the V-phase and the step-down voltage of the W-phase respectively; The clamping unit comprises: a U-phase clamping module, a V-phase clamping module and a W-phase clamping module; wherein the U-phase clamping module, the V-phase clamping module and the W-phase clamping module are respectively used to clamp the step-down voltage of the U-phase, the step-down voltage of the V-phase and the step-down voltage of the W-phase accordingly, so as to obtain the clamping voltage of the U-phase, the clamping voltage of the V-phase and the clamping voltage of the W-phase respectively; The filtering unit includes: a U-phase filtering module, a V-phase filtering module and a W-phase filtering module; wherein the U-phase filtering module, the V-phase filtering module and the W-phase filtering module are respectively used to filter the clamping voltage of the U-phase, the clamping voltage of the V-phase and the clamping voltage of the W-phase correspondingly to obtain the filtering voltage of the U-phase, the filtering voltage of the V-phase and the filtering voltage of the W-phase respectively.

3. The voltage fault detection device for a three-phase AC power supply according to claim 2, characterized in that: The structures of the U-phase sampling module, the V-phase sampling module and the W-phase sampling module are the same; The U-phase sampling module includes: a first voltage-dividing resistor module and a second voltage-dividing resistor module; wherein, The U-phase input terminal among the three-phase input terminals is connected to the first connection terminal of the U-phase inductor among the three-phase common-mode inductor; the second connection terminal of the U-phase inductor is connected to the first connection terminal of the U-phase step-down module in the step-down unit after passing through the first voltage-dividing resistor module; the second connection terminal of the U-phase step-down module is grounded after passing through the second voltage-dividing resistor module.

4. The voltage fault detection device for a three-phase AC power supply according to claim 3, characterized in that: The first voltage-dividing resistor module comprises: n sub-resistance modules, where n is a positive integer; in the first voltage-dividing resistor module, when n is greater than or equal to 2, the n sub-resistance modules are arranged in series.

5. The voltage fault detection device for a three-phase AC power supply according to claim 3, characterized in that: The U-phase sampling module further includes: a first capacitor module; the first capacitor module is connected in parallel to both ends of the second voltage-dividing resistor module.

6. The voltage fault detection device for a three-phase AC power supply according to any one of claims 1 to 5, characterized in that: The U-phase buck module, the V-phase buck module and the W-phase buck module have the same structure; the U-phase buck module includes: a buck diode module; wherein, The anode of the buck diode module serves as the first connection end of the U-phase buck module; the cathode of the buck diode module serves as the second connection end of the U-phase buck module; The second connection end of the U-phase buck module is connected to the clamping end of the U-phase clamping module in the clamping unit; the second connection end of the U-phase buck module is also connected to the first connection end of the U-phase filter module in the filter unit.

7. The voltage fault detection device for a three-phase AC power supply according to any one of claims 1 to 6, characterized in that: The U-phase clamping module, the V-phase clamping module and the W-phase clamping module have the same structure; The U-phase clamping module comprises: a clamping diode module; the clamping diode module comprises: a first sub-diode module and a second sub-diode module; wherein, The anode of the first sub-diode module is grounded, the cathode of the first sub-diode module is connected to the anode of the second sub-diode module, and the cathode of the second sub-diode module is used to connect to a preset DC power supply; the common end of the first sub-diode module and the second sub-diode module serves as the clamping end of the U-phase clamping module and is connected to the second connection end of the U-phase buck module in the buck unit; wherein the preset DC power supply is used to provide a power supply voltage within the allowable voltage range of the control unit.

8. The voltage fault detection device for a three-phase AC power supply according to any one of claims 1 to 7, characterized in that: The structures of the U-phase filter module, the V-phase filter module and the W-phase filter module are the same; The U-phase filter module includes: a filter resistor module and a filter capacitor module; wherein, The second connection end of the U-phase step-down module in the step-down unit is grounded after passing through the filter resistor module and the filter capacitor module; the common end of the filter resistor module and the filter capacitor module serves as the output end of the U-phase filter module, and is used to output the U-phase filtered voltage to the sampling end of the control unit.

9. A motor controller, characterized in that: include: A voltage fault detection device for a three-phase AC power supply according to any one of claims 1 to 8.

10. A method for detecting voltage fault of a motor controller as claimed in claim 9, characterized in that: include: By means of the sampling unit, each phase current of the three-phase current input by the three-phase AC power supply is sampled separately between the three-phase common-mode inductor and the rectifier bridge to obtain a sampled voltage of each phase; The step-down unit is used to step down the sampled voltage of each phase to obtain a step-down voltage of each phase; By means of the clamping unit, the step-down voltage of each phase is clamped according to the allowable voltage range of the control unit to obtain a clamping voltage of each phase; The clamping voltage of each phase is filtered by the filtering unit to obtain a filtered voltage of each phase; Determine whether the phase voltage of each phase of the three-phase AC power supply is faulty based on the filtered voltage of each phase; and, when it is determined that the phase voltage of each phase of the three-phase AC power supply is faulty, initiate a reminder message of the phase voltage fault of each phase of the three-phase AC power supply, so as to protect the three-phase AC power supply and its load by controlling the three-phase AC power supply to stop power supply.

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