Frequency conversion unit and fault determination method and device thereof, storage medium and program product

Abstract

The invention discloses a frequency conversion unit and a fault determination method and device thereof, a storage medium and a computer program product. The method comprises the following steps: applying control signals with different parameters to two adjacent phases of bridge arms in a U-phase bridge arm, a V-phase bridge arm and a W-phase bridge arm; determining winding parameters of each phase of winding in the two adjacent phases of windings according to the direct current bus voltage of the input side of the inverter, the back electromotive force of the motor and the current parameters of the two adjacent phases of windings corresponding to the two adjacent phases of bridge arms; determining winding parameters of each phase of winding in the U-phase winding, the V-phase winding and the W-phase winding; and according to the winding parameters of each phase of winding in the U-phase winding, the V-phase winding and the W-phase winding, determining whether the motor has a fault and determining a fault winding under the condition that the motor has the fault so as to realize fault positioning of the motor. According to the scheme, the voltage of different frequencies is applied to the inverter of the motor, and then the current parameters of the motor are obtained so as to detect and position the motor fault, which is accurate and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of variable frequency units, and specifically relates to a method, device, variable frequency unit, storage medium and computer program product for determining faults of a variable frequency unit, and more particularly to a method, device, variable frequency unit, storage medium and computer program product for detecting abnormal parameters of a variable frequency air-conditioning compressor and a motor based on voltage and current parameters. Background Art

[0002] With the increasing application of variable frequency drives (such as fans and compressor drives of variable frequency units), variable frequency drive failures are also increasing, and after-sales maintenance of products is becoming more and more difficult. Therefore, how after-sales products themselves can accurately locate variable frequency unit failures and quickly solve problems has become an issue that needs to be studied after the equipment is converted to frequency.

[0003] 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

[0004] The object of the present invention is to provide a fault determination method, device, frequency conversion unit, storage medium and computer program product for a frequency conversion unit to solve the problem of how to quickly and accurately locate the motor fault of the frequency conversion unit, so as to achieve the effect of applying voltages of different frequencies to the inverter circuit of the motor, and then obtaining the current parameters of the motor to detect and locate the motor fault accurately and efficiently.

[0005] The present invention provides a method for determining a fault of a frequency conversion unit, wherein the load of the frequency conversion unit has a motor, and the motor has a U-phase winding, a V-phase winding and a W-phase winding; the inverter of the motor comprises: a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube and a sixth switch tube, wherein the first switch tube and the second switch tube are connected in series up and down to form a U-phase bridge arm, the third switch tube and the fourth switch tube are connected in series up and down to form a V-phase bridge arm, and the fifth switch tube and the sixth switch tube are connected in series up and down to form a W-phase bridge arm; the method for determining a fault of the frequency conversion unit comprises: obtaining a DC bus voltage on an input side of the inverter, and obtaining a back electromotive force of the motor; supplying a DC bus voltage to adjacent ones of the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm; Apply control signals with different parameters to the two-phase bridge arms; obtain current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding and the W-phase winding; determine the winding parameters of each phase winding in the adjacent two-phase windings according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the adjacent two-phase windings; thereby determine the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding; determine whether the motor fails according to the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding, and determine the faulty winding of the motor when the motor fails, so as to realize fault detection and positioning of the motor.

[0006] In some embodiments, the control signals with different parameters include: PWM signals with different carrier frequencies and the same duty cycle; the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm include: the adjacent two-phase bridge arms with the U-phase bridge arm as the first phase bridge arm and the V-phase bridge arm as the second phase bridge arm, and / or the adjacent two-phase bridge arms with the V-phase bridge arm as the first phase bridge arm and the W-phase bridge arm as the second phase bridge arm; applying control signals with different parameters to the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm includes: applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm after a set time interval. A PWM signal with a second set carrier frequency and a set duty cycle is used to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the second set carrier frequency is greater than the first set carrier frequency; after a set time interval, a PWM signal with a third set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the third set carrier frequency is greater than the second set carrier frequency; after a set time interval, a PWM signal with a fourth set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the fourth set carrier frequency is greater than the third set carrier frequency.

[0007] In some embodiments, obtaining current parameters of two adjacent phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding, and the W-phase winding includes: after applying control signals with different parameters to the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm, and the W-phase bridge arm, when the corresponding switch tubes in the adjacent two-phase bridge arms are controlled to be turned on, collecting the current flowing through the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding, and the W-phase winding at the middle position of the control signals with different parameters as the U Phase winding, current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms in the V-phase winding and the W-phase winding; wherein, when the first phase bridge arm in the adjacent two-phase bridge arms is the U-phase bridge arm and the second phase bridge arm in the adjacent two-phase bridge arms is the V-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms are the U-phase current and the V-phase current; when the first phase bridge arm in the adjacent two-phase bridge arms is the V-phase bridge arm and the second phase bridge arm in the adjacent two-phase bridge arms is the W-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms are the V-phase current and the W-phase current.

[0008] In some embodiments, the winding parameters of each phase winding in the two adjacent phase windings include: the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings; determining the winding parameters of each phase winding in the two adjacent phase windings according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings, including: determining the difference between the DC bus voltage on the input side of the inverter and the back electromotive force of the motor, recorded as the power supply voltage difference of the motor; according to the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the two adjacent phase windings, calculating the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings as the winding parameters of each phase winding in the two adjacent phase windings; wherein the current parameters of the two adjacent phase windings include: in the upper bridge arm of the first phase bridge arm in the two adjacent phase windings, and the second phase bridge arm in the two adjacent phase windings. The first phase current and the second phase current of the first group are obtained after a PWM signal with a first set carrier frequency and a set duty cycle is applied to the lower bridge arm of the phase bridge arm; the first phase current and the second phase current of the second group are obtained after a PWM signal with a second set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm in the adjacent two-phase winding and the lower bridge arm of the second phase bridge arm in the adjacent two-phase winding; the first phase current and the second phase current of the third group are obtained after a PWM signal with a third set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm in the adjacent two-phase winding and the lower bridge arm of the second phase bridge arm in the adjacent two-phase winding; the first phase current and the second phase current of the fourth group are obtained after a PWM signal with a fourth set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm in the adjacent two-phase winding and the lower bridge arm of the second phase bridge arm in the adjacent two-phase winding.

[0009] In some embodiments, the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the adjacent two-phase windings includes the following formula: Upn-e=a i *R 1i +jwL 1i *a i -b i *R 2i +jwL 2i *b i ; Wherein, Upn-e is the power supply voltage difference of the motor, a i 、b i is the first phase current and the second phase current of the i-th group of the current parameters of the adjacent two-phase windings obtained, R 1i , L 1i is the equivalent resistance and equivalent inductance of the first phase winding in the adjacent two-phase winding, R 2i , L 2iare the equivalent resistance and equivalent inductance of the second phase winding in the adjacent two-phase windings; w=2πf, f is the different carrier frequencies in the control signals with different parameters.

[0010] In some embodiments, the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding include: the equivalent resistance of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, and the equivalent inductance of each phase winding; according to the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, determining whether the motor fails, and determining the faulty winding of the motor when the motor fails, including: for the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, determining whether The resistance error between the equivalent resistance of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding and the preset standard resistance is within the set resistance error range, and the inductance error between the equivalent inductance of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding and the preset standard inductance is within the set inductance error range; if it is determined that the conditions are met, it is determined that the motor has not failed; if it is determined that the conditions are not met, it is determined that the motor has failed, and the fault resistance of the motor is the corresponding phase winding whose resistance error is not within the set resistance error range and / or whose inductance error is not within the set inductance error range.

[0011] Matching the above method, the present invention provides a fault determination device for a frequency conversion unit on the other hand, wherein the load of the frequency conversion unit has a motor, and the motor has a U-phase winding, a V-phase winding and a W-phase winding; the inverter of the motor comprises: a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube and a sixth switch tube, wherein the first switch tube and the second switch tube are connected in series up and down to form a U-phase bridge arm, the third switch tube and the fourth switch tube are connected in series up and down to form a V-phase bridge arm, and the fifth switch tube and the sixth switch tube are connected in series up and down to form a W-phase bridge arm; the fault determination device for the frequency conversion unit comprises: an acquisition unit, configured to acquire a DC bus voltage on the input side of the inverter and acquire a back electromotive force of the motor; a control unit, configured to provide a DC bus voltage to adjacent two phase bridges among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm. The control arm applies a control signal with different parameters; the acquisition unit is further configured to acquire the current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding and the W-phase winding; the control unit is further configured to determine the winding parameters of each phase winding in the adjacent two-phase windings according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the adjacent two-phase windings; thereby determining the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding; the control unit is further configured to determine whether the motor fails according to the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding, and determine the faulty winding of the motor when the motor fails, so as to realize fault detection and positioning of the motor.

[0012] In some embodiments, the control signals with different parameters include: PWM signals with different carrier frequencies and the same duty cycle; the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm include: the adjacent two-phase bridge arms with the U-phase bridge arm as the first phase bridge arm and the V-phase bridge arm as the second phase bridge arm, and / or the adjacent two-phase bridge arms with the V-phase bridge arm as the first phase bridge arm and the W-phase bridge arm as the second phase bridge arm; the control unit applies control signals with different parameters to the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm, including: applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to turn on; after a set time interval, applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm ... A PWM signal with a second set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the second set carrier frequency is greater than the first set carrier frequency; after a set time interval, a PWM signal with a third set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the third set carrier frequency is greater than the second set carrier frequency; after a set time interval, a PWM signal with a fourth set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the fourth set carrier frequency is greater than the third set carrier frequency.

[0013] In some embodiments, the acquisition unit acquires the current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding, and the W-phase winding, including: after applying control signals with different parameters to the adjacent two-phase bridge arms in the U-phase bridge arm, the V-phase bridge arm, and the W-phase bridge arm, when the corresponding switch tubes in the adjacent two-phase bridge arms have been controlled to open, at the middle position of the control signals with different parameters, collecting the currents flowing through the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding, and the W-phase winding as Current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding and the W-phase winding; wherein, when the first phase bridge arm among the adjacent two-phase bridge arms is the U-phase bridge arm and the second phase bridge arm among the adjacent two-phase bridge arms is the V-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms are the U-phase current and the V-phase current; when the first phase bridge arm among the adjacent two-phase bridge arms is the V-phase bridge arm and the second phase bridge arm among the adjacent two-phase bridge arms is the W-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms are the V-phase current and the W-phase current.

[0014] In some embodiments, the winding parameters of each phase winding in the two adjacent phase windings include: the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings; the control unit determines the winding parameters of each phase winding in the two adjacent phase windings according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings, including: determining the difference between the DC bus voltage on the input side of the inverter and the back electromotive force of the motor, recorded as the power supply voltage difference of the motor; according to the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the two adjacent phase windings, calculating the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings as the winding parameters of each phase winding in the two adjacent phase windings; wherein the current parameters of the two adjacent phase windings include: in the upper bridge arm of the first phase bridge arm in the two adjacent phase windings, and the upper bridge arm of the two adjacent phase windings The first phase current and the second phase current of the first group are obtained after a PWM signal with a first set carrier frequency and a set duty cycle is applied to the lower bridge arm of the second phase bridge arm in the group; the first phase current and the second phase current of the second group are obtained after a PWM signal with a second set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm in the adjacent two-phase winding and the lower bridge arm of the second phase bridge arm in the adjacent two-phase winding; the first phase current and the second phase current of the third group are obtained after a PWM signal with a third set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm in the adjacent two-phase winding and the lower bridge arm of the second phase bridge arm in the adjacent two-phase winding; the first phase current and the second phase current of the fourth group are obtained after a PWM signal with a fourth set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm in the adjacent two-phase winding and the lower bridge arm of the second phase bridge arm in the adjacent two-phase winding.

[0015] In some embodiments, the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the adjacent two-phase windings includes the following formula: Upn-e=a i *R 1i +jwL 1i *a i -b i *R 2i +jwL 2i *b i ; Wherein, Upn-e is the power supply voltage difference of the motor, a i 、b i is the first phase current and the second phase current of the i-th group of the current parameters of the adjacent two-phase windings obtained, R 1i , L 1i is the equivalent resistance and equivalent inductance of the first phase winding in the adjacent two-phase winding, R 2i , L 2iare the equivalent resistance and equivalent inductance of the second phase winding in the adjacent two-phase windings; w=2πf, f is the different carrier frequencies in the control signals with different parameters.

[0016] In some embodiments, the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding include: the equivalent resistance of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, and the equivalent inductance of each phase winding; the control unit determines whether the motor fails according to the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, and determines the faulty winding of the motor when the motor fails, including: determining whether the motor fails according to the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding. Whether the resistance error between the equivalent resistance of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding and the preset standard resistance is within the set resistance error range, and the inductance error between the equivalent inductance of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding and the preset standard inductance is within the set inductance error range; if it is determined that it is satisfied, it is determined that the motor has not failed; if it is determined that it is not satisfied, it is determined that the motor has failed, and the fault resistance of the motor is the corresponding phase winding whose resistance error is not within the set resistance error range and / or the inductance error is not within the set inductance error range.

[0017] Matching the above-mentioned device, the present invention provides a frequency conversion unit on another aspect, including: the fault determination device of the frequency conversion unit mentioned above.

[0018] In accordance with the above method, the present invention provides a storage medium on the other hand, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the above-mentioned method for determining the fault of the variable frequency unit.

[0019] In accordance with the above method, the present invention further provides a computer program product, including a computer program, which implements the steps of the above-mentioned method for determining faults of variable frequency units when executed by a processor.

[0020] Therefore, the scheme of the present invention, for the motor in the load of the frequency conversion unit (such as the motor in the fan and the compressor), for the three-phase full-bridge inverter circuit in the inverter of the motor, applies PWM signals with different carrier frequencies and the same duty cycle to the switch tube of the upper bridge arm of one phase bridge arm and the switch tube of the lower bridge arm of the other phase bridge arm in the adjacent two-phase bridge arms, collects the current of the adjacent two phase windings in the three-phase winding of the motor, and calculates the equivalent resistance and equivalent inductance of the adjacent two phase windings in the three-phase winding of the motor; similarly, calculates the equivalent resistance and equivalent inductance of the third phase winding in the three-phase winding of the motor; then, based on the equivalent resistance and equivalent inductance of the three-phase winding of the motor, determines whether the motor is abnormal, and when it is determined that the motor is abnormal, which phase winding is abnormal, so as to locate the motor fault; thus, by applying voltages of different frequencies to the inverter circuit of the motor, the current parameters of the motor are obtained to detect and locate the motor fault accurately and efficiently.

[0021] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic flow chart of an embodiment of a method for determining a fault of a frequency conversion unit of the present invention;

[0024] Figure 2 A schematic diagram of a flow chart of an embodiment of applying control signals with different parameters in the method of the present invention;

[0025] Figure 3 A schematic diagram of a flow chart of an embodiment of determining the winding parameters of each phase winding in the two adjacent phase windings in the method of the present invention;

[0026] Figure 4 A flow chart of an embodiment of the method of the present invention for determining whether the motor is faulty and determining a faulty winding of the motor when the motor is faulty;

[0027] Figure 5 A schematic structural diagram of an embodiment of a device for determining a fault of a frequency conversion unit according to the present invention;

[0028] Figure 6 It is a schematic diagram of the structure of the inverter control system of the compressor or fan of the variable frequency air conditioner;

[0029] Figure 7 It is a schematic diagram of the distribution of voltage and current acquisition parameters of the inverter control system;

[0030] Figure 8 This is a structural diagram of the equivalent circuit inside the motor.

[0031] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0032] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0033] 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 creative work are within the scope of protection of the present invention.

[0034] The frequency conversion unit is a system that can control the output torque and speed of the motor. It controls the operation of the motor by adjusting the power supply frequency. Frequency conversion units, such as frequency conversion air conditioners, frequency conversion refrigerators, etc. The problem of how to accurately locate the fault of the frequency conversion unit. The treatment plan in the relevant plan does not judge the status of the motor and compressor (i.e., compressor) on the load side, and the after-sales staff do not have professional equipment. Usually, they can only measure the control board, motor, and compressor through simple equipment such as multimeters, and cannot completely and accurately locate the fault.

[0035] Usually when an air-conditioning unit has a problem, the after-sales staff will divide it into sections and handle it accordingly. The sections are usually roughly divided into controllers, routing, wiring, loads, compressors, fans, systems, and pipelines. When actually handling the fault problem, they follow the principle of replacing the easy ones first and then the difficult ones. They will replace the control board first. If there is no effect, they will replace the corresponding motor and compressor, instead of locating the compressor and fan at one time, which leads to inaccurate positioning, increased workload, and increased time.

[0036] Therefore, the scheme of the present invention proposes a fault determination method for a variable frequency unit, specifically a variable frequency air-conditioning compressor and motor parameter abnormality detection method based on voltage and current parameters. Based on the voltage and current sampling parameters, a method for identifying abnormal compressor and motor parameters is realized by calculating through a variable frequency drive algorithm, thereby more accurately locating the compressor and motor fault types.

[0037] According to an embodiment of the present invention, a method for determining a fault of a frequency conversion unit is provided, such as Figure 1The flow chart of an embodiment of the method of the present invention is shown. The load of the frequency conversion unit has a motor, and the motor has a U-phase winding, a V-phase winding and a W-phase winding; the inverter of the motor includes: a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube and a sixth switch tube, the first switch tube and the second switch tube are connected in series up and down to form a U-phase bridge arm, the third switch tube and the fourth switch tube are connected in series up and down to form a V-phase bridge arm, the fifth switch tube and the sixth switch tube are connected in series up and down to form a W-phase bridge arm, the first switch tube is such as a switch tube K1, the second switch tube is such as a switch tube K2, the third switch tube is such as a switch tube K3, the fourth switch tube is such as a switch tube K4, the fifth switch tube is such as a switch tube K5, and the sixth switch tube is such as a switch tube K6; the midpoint of the U-phase bridge arm is connected to the power supply end of the U-phase winding, the midpoint of the V-phase bridge arm is connected to the power supply end of the V-phase winding, and the midpoint of the W-phase bridge arm is connected to the power supply end of the W-phase winding. Figure 6 The following is a schematic diagram of the structure of the inverter control system of the compressor or fan of the variable frequency air conditioner. Figure 6 As shown, this topology is the main topology of the inverter circuit of the frequency converter, wherein the P terminal and the N terminal are the positive terminal and the negative terminal of the input DC bus voltage, the capacitor C1 is the bus capacitor, the switch tube K1, the switch tube K2, the switch tube K3, the switch tube K4, the switch tube K5, and the switch tube K6 are inverter tubes, and the diode D1, the diode D2, the diode D3, the diode D4, the diode D5, and the diode D6 are freewheeling diodes of the inverter circuit. The capacitor C1 and the inverter circuit are sequentially arranged between the output end of the DC bus voltage and the power supply end of the three-phase winding of the motor.

[0038] The inverter tube can be a P-channel insulated-gate bipolar transistor (IGBT) or an N-channel IGBT. For example, when the inverter tube is a P-channel IGBT, the diode D1 is a freewheeling diode of the switch tube K1, the cathode of the diode D1 is connected to the collector of the switch tube K1, and the anode of the diode D1 is connected to the emitter of the switch tube K1; the diode D2 is a freewheeling diode of the switch tube K2, the cathode of the diode D2 is connected to the collector of the switch tube K2, and the anode of the diode D2 is connected to the emitter of the switch tube K2; the diode D3 is a freewheeling diode of the switch tube K3, the cathode of the diode D3 is connected to the collector of the switch tube K3, and the anode of the diode D3 is connected to the emitter of the switch tube K2. The diode D4 is a freewheeling diode of the switch tube K4, the cathode of the diode D4 is connected to the collector of the switch tube K4, and the anode of the diode D4 is connected to the emitter of the switch tube K4; the diode D5 is a freewheeling diode of the switch tube K5, the cathode of the diode D5 is connected to the collector of the switch tube K5, and the anode of the diode D5 is connected to the emitter of the switch tube K5; the diode D6 is a freewheeling diode of the switch tube K6, the cathode of the diode D6 is connected to the collector of the switch tube K6, and the anode of the diode D6 is connected to the emitter of the switch tube K6.

[0039] In the inverter circuit, the switch tube K1 as the upper bridge arm and the switch tube K2 as the lower bridge arm are connected in series to form a first-phase bridge arm (such as a U-phase bridge arm), and the midpoint of the first-phase bridge arm is connected to the power supply end of the first-phase winding (such as the U-phase winding) in the three-phase winding of the motor; in the inverter circuit, the switch tube K3 as the upper bridge arm and the switch tube K4 as the lower bridge arm are connected in series to form a second-phase bridge arm (such as a V-phase bridge arm), and the midpoint of the second-phase bridge arm is connected to the power supply end of the second-phase winding (such as the V-phase winding) in the three-phase winding of the motor; in the inverter circuit, the switch tube K5 as the upper bridge arm and the switch tube K6 as the lower bridge arm are connected in series to form a third-phase bridge arm (such as a W-phase bridge arm), and the midpoint of the third-phase bridge arm is connected to the power supply end of the third-phase winding (such as the W-phase winding) in the three-phase winding of the motor. In the scheme of the present invention, Figure 1 As shown, the method for determining faults of the variable frequency unit includes: steps S110 to S150.

[0040] In step S110, the DC bus voltage on the input side of the inverter is obtained, and the back electromotive force of the motor is obtained, wherein the DC bus voltage on the input side of the inverter is such as voltage Upn, and the back electromotive force of the motor is such as voltage e.

[0041] At step S120, control signals with different parameters (such as control signals with different voltage parameters) are applied to two adjacent phases of the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm. Specifically, PWM signals with different set frequencies and the same duty cycle are applied to two adjacent phases of the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm.

[0042] In some embodiments, the control signals with different parameters include: PWM signals with different carrier frequencies and the same duty cycle; the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm include: the adjacent two-phase bridge arms with the U-phase bridge arm as the first phase bridge arm and the V-phase bridge arm as the second phase bridge arm, and / or the adjacent two-phase bridge arms with the V-phase bridge arm as the first phase bridge arm and the W-phase bridge arm as the second phase bridge arm.

[0043] For the specific process of applying control signals with different parameters to two adjacent phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm in step S120, refer to the following exemplary description.

[0044] Combine the following Figure 2 The flowchart of an embodiment of applying control signals with different parameters in the method of the present invention further illustrates the specific process of applying control signals with different parameters in step S120, including: step S210 to step S240.

[0045] Step S210, applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open. Among them, the first set carrier frequency is a given carrier frequency of 2kHz, and the duty cycle is set to 50%. For example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of the PWM signal G1 and the PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 2kHz, and the given duty cycle is 50%.

[0046] Step S220, after setting the time interval, apply a PWM signal with a second set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the second set carrier frequency is greater than the first set carrier frequency. The second set carrier frequency is such as the given carrier frequency of 5kHz, and the duty cycle is set to 50%. For example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of PWM signal G1 and PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 5kHz, and the given duty cycle is 50%.

[0047] Step S230, after setting the time interval, apply a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the third set carrier frequency is greater than the second set carrier frequency. The third set carrier frequency is such as the given carrier frequency of 7kHz, and the duty cycle is set to 50%. For example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of PWM signal G1 and PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 7kHz, and the given duty cycle is 50%.

[0048] Step S240, after setting the time interval, apply a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the fourth set carrier frequency is greater than the third set carrier frequency. wherein the fourth set carrier frequency is such as the given carrier frequency of 9kHz, and the duty cycle is set to 50%. for example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of the PWM signal G1 and the PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 9kHz, and the given duty cycle is 50%.

[0049] Figure 7 The diagram below is a schematic diagram of the distribution of voltage and current acquisition parameters of the inverter control system. Figure 7 As shown, in Figure 6 On the basis of the inverter control system of the compressor or fan of the variable frequency air conditioner shown, driving PWM control signals of PWM signal G1, PWM signal G2, PWM signal G3, PWM signal G4, PWM signal G5, and PWM signal G6 are given according to the variable frequency control principle, thereby realizing the control operation of the subsequent load motor or compressor.

[0050] In the scheme of the present invention, the control of the motor is achieved by controlling the PWM signal G1, PWM signal G2, PWM signal G3, PWM signal G4, PWM signal G5, and PWM signal G6. The subsequent fault detection is also achieved by injecting a current of a certain frequency into the motor through these signal controls. By detecting these currents, the internal parameters of the motor and the press are reversely deduced, and the derived equivalent parameters are compared with the specification sheet, thereby accurately locating the cause of the motor failure. The fault cause can be quickly located, the maintenance efficiency can be improved, the after-sales maintenance cost can be reduced, and the problem of inaccurate positioning of the cause of the after-sales maintenance fault is solved.

[0051] In step S130, current parameters of two adjacent phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding and the W-phase winding are obtained.

[0052] In some embodiments, step S130 obtains current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding, and the W-phase winding, including: after applying control signals of different parameters to the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm, and the W-phase bridge arm, when the corresponding switch tubes in the adjacent two-phase bridge arms have been controlled to open, specifically, when the switch tube of the upper bridge arm of the first phase bridge arm of the adjacent two-phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm of the adjacent two-phase bridge arm are controlled to open, at the middle position of the control signals of different parameters, the current flowing through the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding, and the W-phase winding is collected as the current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding, and the W-phase winding.

[0053] like Figure 7 As shown, in the inverter circuit, a resistor R11 is provided between the first phase bridge arm and the N end of the DC bus voltage, a resistor R12 is provided between the second phase bridge arm and the N end of the DC bus voltage, and a resistor R13 is provided between the third phase bridge arm and the N end of the DC bus voltage; a resistor R4 is provided between the P end of the DC bus voltage and the inverter circuit. In the process of realizing the fault diagnosis of the motor or the compressor, it is first necessary to collect the voltages at both ends of the P end and the N end. The voltage is the DC voltage of the DC frequency conversion, and the value of the voltage feedback is whether the power supply of the front end of the inverter module is normal. For the detection of the bus DC voltage, it is only before the detection of the motor and the compressor that it is necessary to first ensure that the power supply status of the motor controller itself is not a problem. Usually there is a working area for the bus voltage input. For example, the bus voltage is defined as Vp, and the minimum and maximum values ​​that the bus can work are Vmin and Vmax respectively, then Vmin≤Vp≤Vmax.

[0054] The implementation process of current sampling is as follows: different frequency conversion control schemes have different sampling schemes. The scheme of the present invention provides three basic sampling methods as examples. In practical applications, only one of them is needed to achieve control. The first method is to collect the current on resistor R4 to achieve single resistor sampling control; the second method is to collect the current on resistor R11, resistor R12, resistor R13 or the current on two of the resistors to achieve control; the third method is to collect current a, current b and current c flowing into the press or motor or two of the currents to achieve control of the press or motor. There is no essential difference between the three schemes. Each of them can realize the collection of current. In actual use, you can choose which method to use based on cost, reliability and other considerations.

[0055] Wherein, when the first phase bridge arm of the adjacent two-phase bridge arm is the U-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arm are the U-phase current and the V-phase current. For example: the control inverter continuously gives the control signals of the PWM signal G1 and the PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 2kHz, the given duty cycle is 50%, and the current a and the current b flowing through are collected at the middle position of the control signals of the PWM signal G1 and the PWM signal G4.

[0056] In the case where the first phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the W-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arm are the V-phase current and the W-phase current. For example: the control inverter continuously gives the control signals of the PWM signal G3 and the PWM signal G6, turns on the switch tube K3 and the switch tube K6, the given carrier frequency is 2kHz, the given duty cycle is 50%, and the current b and the current c flowing through are collected at the middle position of the control signals of the PWM signal G3 and the PWM signal G6.

[0057] The scheme of the present invention realizes the control of the motor by controlling PWM signal G1, PWM signal G2, PWM signal G3, PWM signal G4, PWM signal G5 and PWM signal G6, and injects a current of a certain frequency into the motor during fault inspection, thereby obtaining the current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding and the W-phase winding, so as to detect these currents and then reversely deduce the internal parameters of the motor and the compressor, and compare the derived equivalent parameters with the specification sheet, thereby realizing rapid and accurate positioning of the cause of the motor fault.

[0058] At step S140, the winding parameters of each phase winding in the two adjacent phase windings are determined according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings, specifically, the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings are determined; thereby, the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding are determined, specifically, the equivalent resistance and equivalent inductance of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding are determined.

[0059] In some embodiments, when the first phase bridge arm of the two adjacent phase bridge arms is the U phase bridge arm and the second phase bridge arm of the two adjacent phase bridge arms is the V phase bridge arm, the current parameters of the two adjacent phase windings include: U phase current and V phase current; when the first phase bridge arm of the two adjacent phase bridge arms is the V phase bridge arm and the second phase bridge arm of the two adjacent phase bridge arms is the W phase bridge arm, the current parameters of the two adjacent phase windings include: V phase current and W phase current; the winding parameters of each phase winding in the two adjacent phase windings include: equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings.

[0060] For the specific process of determining the winding parameters of each phase winding in the two adjacent phase windings according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings in step S140, please refer to the following exemplary description.

[0061] Combine the following Figure 3 The flowchart of an embodiment of determining the winding parameters of each phase winding in the two adjacent phase windings in the method of the present invention further illustrates the specific process of determining the winding parameters of each phase winding in the two adjacent phase windings in step S140, including: steps S310 to S320.

[0062] Step S310, determining a difference between a DC bus voltage at the input side of the inverter and a back electromotive force of the motor, and recording the difference as a power supply voltage difference of the motor.

[0063] Step S320, according to the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the two adjacent phase windings, the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings are calculated as the winding parameters of each phase winding in the two adjacent phase windings.

[0064] The current parameters of the adjacent two-phase windings include: a first group of first-phase currents and second-phase currents obtained after applying a PWM signal with a first set carrier frequency and a set duty cycle to an upper bridge arm of a first-phase bridge arm in the adjacent two-phase windings and a lower bridge arm of a second-phase bridge arm in the adjacent two-phase windings; a second group of first-phase currents and second-phase currents obtained after applying a PWM signal with a second set carrier frequency and a set duty cycle to an upper bridge arm of a first-phase bridge arm in the adjacent two-phase windings and a lower bridge arm of a second-phase bridge arm in the adjacent two-phase windings. phase current and second-phase current; the first-phase current and second-phase current of the third group obtained after applying a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings; the first-phase current and second-phase current of the fourth group obtained after applying a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings.

[0065] Specifically, in the case where the first phase bridge arm of the adjacent two-phase bridge arm is the U-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm: after applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and the V-phase current of the first group are obtained; after applying a PWM signal with a second set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and the V-phase current of the second group are obtained; after applying a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and the V-phase current of the second group are obtained. After applying a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and V-phase current of the fourth group are obtained; wherein, the U-phase current and V-phase current of the first group such as current a1 and b1, the U-phase current and V-phase current of the second group such as current a2 and b2, the U-phase current and V-phase current of the third group such as current a3 and b3, and the U-phase current and V-phase current of the fourth group such as current a4 and b4 are respectively the currents detected in the process of measuring the U and V phase motor parameters.

[0066] In the case where the first phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the W-phase bridge arm: after applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the first group of V-phase current and W-phase current are obtained; after applying a PWM signal with a second set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the second group of V-phase current and W-phase current are obtained; after applying a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the third group of V-phase current and W-phase current are obtained; after applying a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the fourth group of V-phase current and W-phase current are obtained.

[0067] The solution of the present invention determines the winding parameters of each phase of the two adjacent phase windings according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings, and compares them with the specification sheet, thereby accurately locating the cause of the motor failure; the cause of the failure can be quickly located, maintenance efficiency can be improved, and after-sales maintenance costs can be reduced.

[0068] In some embodiments, the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the adjacent two-phase windings includes the following formula: Upn-e=a i *R 1i +jwL 1i *a i -b i *R 2i +jwL 2i *b i .

[0069] Wherein, Upn-e is the power supply voltage difference of the motor, a i 、b i is the first phase current and the second phase current of the i-th group of the current parameters of the adjacent two-phase windings obtained, R 1i , L 1i is the equivalent resistance and equivalent inductance of the first phase winding in the adjacent two-phase winding, R 2i , L 2i are the equivalent resistance and equivalent inductance of the second phase winding in the adjacent two-phase windings; w=2πf, f is the different carrier frequencies in the control signals with different parameters.

[0070] Figure 8 This is a structural diagram of the equivalent circuit inside the motor. Figure 8 The equivalent circuit diagram of the compressor or motor is shown in Figure 1. The winding of each phase in the three-phase winding of the motor can be understood as a series circuit of resistance and inductance. The specific values ​​of resistance and inductance of a normal compressor or motor are within a reasonable range. Here, it is assumed that the resistance value in the compressor or motor is R±r (R is the reference value, r is the upper and lower deviation value). Since the characteristics of the three-phase winding inside the motor are basically the same in theory, it is assumed that the resistance values ​​of the other two phases are also R±r. The inductance L1 in the compressor or motor is similar to the resistance characteristics, and the inductance values ​​of the other two phases are also basically the same. Here, it is assumed that the inductance value in the compressor or motor is L±L' (L is the reference value, L' is the upper and lower deviation value). For example: the U-phase winding can be equivalent to a series structure of resistance R1 and inductance L1, the V-phase winding can be equivalent to a series structure of resistance R2 and inductance L2, and the W-phase winding can be equivalent to a series structure of resistance R3 and inductance L3.

[0071] Take the U and V ports as an example to test whether the parameters R1, R2, L1, and L2 in the motor or compressor are normal. The specific test process, i.e. the abnormal detection method of the variable frequency air conditioner compressor and motor parameters based on voltage and current parameters, includes:

[0072] Step 1: First, control the inverter to continuously give the control signals of PWM signal G1 and PWM signal G4, turn on the switch tubes K1 and K4, set the carrier frequency to 2 kHz, set the duty cycle to 50%, and collect the current a and current b flowing through at the middle position of the control signals of PWM signal G1 and PWM signal G4 (i.e., the middle time of the overall time of sending the control signals of PWM signal G1 and PWM signal G4), and then calculate the parameters according to the following formula (1).

[0073] Upn-e=a1*R1+jwL1*a1-b1*R2+jwL2*b1 (1).

[0074] Among them, Upn is the bus voltage at both ends of P and N; e is the motor back electromotive force at this time, and e can be calculated according to the Clark transformation (i.e. Clark transformation) and Park transformation (i.e. Park transformation) in the motor control principle, e=f(a1,b2); a1 and b1 are the currents detected during the measurement of U and V phase motor parameters; R1 and L1 are the resistance and inductance parameters of U phase in the motor and compressor; R2 and L2 are the resistance and inductance parameters of V phase in the motor and compressor.

[0075] Step 2: Repeat the above control signals and collect currents, which are a2 and b2, a3 and b3, a4 and b4 respectively. However, the subsequent carrier frequencies are 5kHz, 7kHz and 9kHz respectively, and the duty cycle given remains unchanged at 50%, thereby further providing formulas (2), (3) and (4).

[0076] Upn-e=a2*R1+jwL1*a2-b2*R2+jwL2*b2 (2);

[0077] Upn-e=a3*R1+jwL1*a3-b3*R2+jwL2*b3 (3);

[0078] Upn-e=a4*R1+jwL1*a4-b4*R2+jwL2*b4 (4).

[0079] Where Upn is the bus voltage at both ends of P and N; e is the motor back electromotive force at this time, which can be calculated based on the Clark transformation (i.e. Clark transformation) and Park transformation (i.e. Park transformation) in the motor control principle, e = f (a1, b2); refer to Figure 8 , R1, L1 are the resistance and inductance parameters of the U phase in the motor and press; R2, L2 are the resistance and inductance parameters of the V phase in the motor and press; R3, L3 are the resistance and inductance parameters of the V phase in the motor and press. Current a1 and b1, current a2 and b2, current a3 and b3, and current a4 and b4 are the currents detected during the measurement of the U and V phase motor parameters. w = 2πf, where f is the carrier frequency each time, which is 2kHz, 5kHz, 7kHz, and 9kHz respectively; j represents the vector angle, specifically 90°.

[0080] Step 3: Calculate R1, R2, L1, and L2 by performing equation calculation on formula (1), formula (2), formula (3), and formula (4).

[0081] Similarly, the same control and measurement are performed on the V and W phases, and the parameters of R3 and L3 are also calculated.

[0082] The solution of the present invention determines the winding parameters of each phase of the two adjacent phase windings according to the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the two adjacent phase windings, and then compares them with the specification sheet, so as to accurately locate the cause of the motor failure; it is possible to quickly locate the cause of the failure, improve maintenance efficiency, and reduce after-sales maintenance costs.

[0083] At step S150, based on the winding parameters of each phase winding among the U-phase winding, the V-phase winding and the W-phase winding, specifically based on the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the equivalent resistance and equivalent inductance of each phase winding among the U-phase winding, the V-phase winding and the W-phase winding, it is determined whether the motor fails, and the faulty winding of the motor is determined when the motor fails, so as to realize fault detection and positioning of the motor.

[0084] The scheme of the present invention provides a variable frequency air-conditioning compressor and motor parameter abnormality detection scheme based on voltage and current parameters, so that the variable frequency drive collects voltage and current parameters, and then realizes variable frequency control of the compressor or motor based on these parameters. Therefore, based on the principle of variable frequency control, the variable frequency drive fault can also be analyzed by reverse deduction with the currently collected voltage and current parameters; in this way, by applying a voltage of a certain frequency to the load control object (electric traction equipment such as a compressor or motor), and then reversely deriving the motor equivalent parameters through the motor equivalent circuit, and comparing the derived equivalent parameters with the specification sheet, the cause of the motor failure can be accurately located; the cause of the fault can be quickly located, the maintenance efficiency can be improved, the after-sales maintenance cost can be reduced, and the problem of inaccurate location of the cause of the after-sales maintenance fault can be solved; for the development of new equipment, previous fault data can be better accumulated, and subsequent development can be more targeted, the development quality can be improved, and the design deficiency of the variable frequency drive during the development of new products can be solved; customer satisfaction can be improved, and the problem of difficulty in verifying after-sales problems can be solved.

[0085] In some embodiments, the winding parameters of each of the U-phase winding, the V-phase winding and the W-phase winding include: the equivalent resistance of each of the U-phase winding, the V-phase winding and the W-phase winding, and the equivalent inductance of each phase winding.

[0086] In step S150, the specific process of determining whether the motor is faulty according to the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding, and determining the faulty winding of the motor when the motor fails, is shown in the following exemplary description.

[0087] Combine the following Figure 4 The method of the present invention is shown as a flowchart of an embodiment of determining whether the motor is faulty and determining the faulty winding of the motor when the motor is faulty, further illustrating the specific process of determining whether the motor is faulty and determining the faulty winding of the motor when the motor is faulty in step S150, including: steps S410 to S430.

[0088] Step S410, for the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding, determine whether the resistance error between the equivalent resistance of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding and a preset standard resistance is within a set resistance error range, and the inductance error between the equivalent inductance of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding and a preset standard inductance is within a set inductance error range.

[0089] Step S420: If the conditions are met, it is determined that the motor is not faulty.

[0090] Step S430: If it is determined that the condition is not satisfied, it is determined that the motor is faulty and the faulty resistance of the motor is a corresponding phase winding whose resistance error is not within a set resistance error range and / or whose inductance error is not within a set inductance error range.

[0091] In the scheme of the present invention, the method for detecting abnormal parameters of the compressor and motor of the variable frequency air conditioner based on voltage and current parameters also includes: comparing the calculated R1, R2, and R3 with the standard value R±r in turn: if it exceeds the range value, it is considered abnormal; if it is within the standard value, the resistance value is considered normal. Similarly, the inductance L1, L2, and L3 are compared with the standard value L±L'. If the resistance value and the inductance value are both within the standard value, the compressor or motor is considered normal. If any value is unexpected from the standard value, the compressor or motor is considered abnormal. By calculating the electrical parameters inside the motor and the compressor, the whole machine checks whether the inductance value inside the motor is abnormal. If it is abnormal, the motor is directly determined to be abnormal without replacing other parts of the unit.

[0092] The solution of the present invention provides a method for identifying abnormal parameters of a press and motor based on voltage and current sampling parameters and by calculating through a variable frequency drive algorithm, so as to more accurately locate the type of press and motor faults. That is to say, the solution of the present invention, based on the control principle of the press and motor, reversely deduce the press and motor parameters according to the collected voltage and current, to realize the identification of the parameters of the press and motor body, so as to determine whether the press and motor are faulty, and accurately locate the type of fault and parameter of the motor internal fault. In the solution of the present invention, a method of actively detecting the parameters of the press and motor is adopted, which solves the problem of inaccurate positioning of the press and fan faults in the previous fault unit faults, can quickly locate the cause of the fault, improve maintenance efficiency, and reduce after-sales maintenance costs. In the solution of the present invention, active detection of the parameters of the press and motor is adopted, which further refines the fault type and solves the problem of inaccurate fault feedback, so that subsequent fault personnel and developers can better obtain accurate fault data, so that in the subsequent development of new products, they can better refer to the previous fault data, solve the basic platform problems in a targeted manner, and develop better products. In the solution of the present invention, accurate positioning of press and motor faults is adopted, which solves the problem that the customer's group cannot be repaired for a long time after the fault, thereby improving customer satisfaction.

[0093] By adopting the technical solution of this embodiment, for the motor in the load of the frequency conversion unit (such as the motor in the fan and the compressor), for the three-phase full-bridge inverter circuit in the inverter of the motor, PWM signals with different carrier frequencies and the same duty cycle are applied to the switch tube of the upper bridge arm of one phase bridge arm and the switch tube of the lower bridge arm of the other phase bridge arm in the adjacent two-phase bridge arms, the current of the adjacent two-phase windings in the three-phase winding of the motor is collected, and the equivalent resistance and equivalent inductance of the adjacent two-phase windings in the three-phase winding of the motor are calculated; similarly, the equivalent resistance and equivalent inductance of the third phase winding in the three-phase winding of the motor are calculated; then, according to the equivalent resistance and equivalent inductance of the three-phase winding of the motor, it is determined whether the motor is abnormal, and when it is determined that the motor is abnormal, which phase of the winding is abnormal, so as to locate the motor fault; thus, by applying voltages of different frequencies to the inverter circuit of the motor, the current parameters of the motor are obtained to detect and locate the motor fault accurately and efficiently.

[0094] According to an embodiment of the present invention, a fault determination device for a variable frequency machine set corresponding to the fault determination method for the variable frequency machine set is also provided. Figure 5 The structure schematic diagram of an embodiment of the device of the present invention is shown. The load of the frequency conversion unit has a motor, and the motor has a U-phase winding, a V-phase winding and a W-phase winding; the inverter of the motor includes: a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube and a sixth switch tube, the first switch tube and the second switch tube are connected in series up and down to form a U-phase bridge arm, the third switch tube and the fourth switch tube are connected in series up and down to form a V-phase bridge arm, the fifth switch tube and the sixth switch tube are connected in series up and down to form a W-phase bridge arm, the first switch tube is such as a switch tube K1, the second switch tube is such as a switch tube K2, the third switch tube is such as a switch tube K3, the fourth switch tube is such as a switch tube K4, the fifth switch tube is such as a switch tube K5, and the sixth switch tube is such as a switch tube K6; the midpoint of the U-phase bridge arm is connected to the power supply end of the U-phase winding, the midpoint of the V-phase bridge arm is connected to the power supply end of the V-phase winding, and the midpoint of the W-phase bridge arm is connected to the power supply end of the W-phase winding. Figure 6 The following is a schematic diagram of the structure of the inverter control system of the compressor or fan of the variable frequency air conditioner. Figure 6 As shown, this topology is the main topology of the inverter circuit of the frequency converter, wherein the P terminal and the N terminal are the positive terminal and the negative terminal of the input DC bus voltage, the capacitor C1 is the bus capacitor, the switch tube K1, the switch tube K2, the switch tube K3, the switch tube K4, the switch tube K5, and the switch tube K6 are inverter tubes, and the diode D1, the diode D2, the diode D3, the diode D4, the diode D5, and the diode D6 are freewheeling diodes of the inverter circuit. The capacitor C1 and the inverter circuit are sequentially arranged between the output end of the DC bus voltage and the power supply end of the three-phase winding of the motor.

[0095] The inverter tube can be a P-channel insulated-gate bipolar transistor (IGBT) or an N-channel IGBT. For example, when the inverter tube is a P-channel IGBT, the diode D1 is a freewheeling diode of the switch tube K1, the cathode of the diode D1 is connected to the collector of the switch tube K1, and the anode of the diode D1 is connected to the emitter of the switch tube K1; the diode D2 is a freewheeling diode of the switch tube K2, the cathode of the diode D2 is connected to the collector of the switch tube K2, and the anode of the diode D2 is connected to the emitter of the switch tube K2; the diode D3 is a freewheeling diode of the switch tube K3, the cathode of the diode D3 is connected to the collector of the switch tube K3, and the anode of the diode D3 is connected to the emitter of the switch tube K2. The diode D4 is a freewheeling diode of the switch tube K4, the cathode of the diode D4 is connected to the collector of the switch tube K4, and the anode of the diode D4 is connected to the emitter of the switch tube K4; the diode D5 is a freewheeling diode of the switch tube K5, the cathode of the diode D5 is connected to the collector of the switch tube K5, and the anode of the diode D5 is connected to the emitter of the switch tube K5; the diode D6 is a freewheeling diode of the switch tube K6, the cathode of the diode D6 is connected to the collector of the switch tube K6, and the anode of the diode D6 is connected to the emitter of the switch tube K6.

[0096] In the inverter circuit, the switch tube K1 as the upper bridge arm and the switch tube K2 as the lower bridge arm are connected in series to form a first-phase bridge arm (such as a U-phase bridge arm), and the midpoint of the first-phase bridge arm is connected to the power supply end of the first-phase winding (such as the U-phase winding) in the three-phase winding of the motor; in the inverter circuit, the switch tube K3 as the upper bridge arm and the switch tube K4 as the lower bridge arm are connected in series to form a second-phase bridge arm (such as a V-phase bridge arm), and the midpoint of the second-phase bridge arm is connected to the power supply end of the second-phase winding (such as the V-phase winding) in the three-phase winding of the motor; in the inverter circuit, the switch tube K5 as the upper bridge arm and the switch tube K6 as the lower bridge arm are connected in series to form a third-phase bridge arm (such as a W-phase bridge arm), and the midpoint of the third-phase bridge arm is connected to the power supply end of the third-phase winding (such as the W-phase winding) in the three-phase winding of the motor. In the scheme of the present invention, Figure 5 As shown, the fault determination device of the variable frequency unit includes: an acquisition unit 102 and a control unit 104.

[0097] The acquisition unit 102 is configured to acquire the DC bus voltage on the input side of the inverter and acquire the back electromotive force of the motor. The DC bus voltage on the input side of the inverter is such as voltage Upn, and the back electromotive force of the motor is such as voltage e. The specific functions and processing of the acquisition unit 102 refer to step S110.

[0098] The control unit 104 is configured to apply control signals with different parameters to the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm, and the W-phase bridge arm, specifically, to apply PWM signals with different set frequencies and the same duty cycle to the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm, and the W-phase bridge arm. The specific functions and processing of the control unit 104 refer to step S120.

[0099] In some embodiments, the control signals with different parameters include: PWM signals with different carrier frequencies and the same duty cycle; the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm include: the adjacent two-phase bridge arms with the U-phase bridge arm as the first phase bridge arm and the V-phase bridge arm as the second phase bridge arm, and / or the adjacent two-phase bridge arms with the V-phase bridge arm as the first phase bridge arm and the W-phase bridge arm as the second phase bridge arm.

[0100] The control unit 104 applies control signals with different parameters to two adjacent bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm, including:

[0101] The control unit 104 is also specifically configured to apply a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open. The specific functions and processing of the control unit 104 can also be found in step S210. Among them, the first set carrier frequency is such as the given carrier frequency 2kHz, and the duty cycle is set to 50%. For example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of the PWM signal G1 and the PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 2kHz, and the given duty cycle is 50%.

[0102] The control unit 104 is also specifically configured to apply a PWM signal with a second set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm after a set time interval, so as to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the second set carrier frequency is greater than the first set carrier frequency. The specific functions and processing of the control unit 104 can also be found in step S220. The second set carrier frequency is such as the given carrier frequency of 5kHz, and the duty cycle is set to 50%. For example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of PWM signal G1 and PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 5kHz, and the given duty cycle is 50%.

[0103] The control unit 104 is also specifically configured to apply a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm after a set time interval, so as to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the third set carrier frequency is greater than the second set carrier frequency. The specific functions and processing of the control unit 104 can also be found in step S230. The third set carrier frequency is such as the given carrier frequency of 7kHz, and the duty cycle is set to 50%. For example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of PWM signal G1 and PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 7kHz, and the given duty cycle is 50%.

[0104] The control unit 104 is also specifically configured to apply a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm after a set time interval, so as to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the fourth set carrier frequency is greater than the third set carrier frequency. The specific functions and processing of the control unit 104 can also be found in step S240. Among them, the fourth set carrier frequency is such as the given carrier frequency of 9kHz, and the duty cycle is set to 50%. For example: taking the two ports U and V as an example, the control inverter continuously gives the control signals of the PWM signal G1 and the PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 9kHz, and the given duty cycle is 50%.

[0105] Figure 7 The diagram below is a schematic diagram of the distribution of voltage and current acquisition parameters of the inverter control system. Figure 7 As shown, in Figure 6 On the basis of the inverter control system of the compressor or fan of the variable frequency air conditioner shown, driving PWM control signals of PWM signal G1, PWM signal G2, PWM signal G3, PWM signal G4, PWM signal G5, and PWM signal G6 are given according to the variable frequency control principle, thereby realizing the control operation of the subsequent load motor or compressor.

[0106] In the scheme of the present invention, the control of the motor is achieved by controlling the PWM signal G1, PWM signal G2, PWM signal G3, PWM signal G4, PWM signal G5, and PWM signal G6. The subsequent fault detection is also achieved by injecting a current of a certain frequency into the motor through these signal controls. By detecting these currents, the internal parameters of the motor and the press are reversely deduced, and the derived equivalent parameters are compared with the specification sheet, thereby accurately locating the cause of the motor failure. The fault cause can be quickly located, the maintenance efficiency can be improved, the after-sales maintenance cost can be reduced, and the problem of inaccurate positioning of the cause of the after-sales maintenance fault is solved.

[0107] The acquisition unit 102 is further configured to acquire current parameters of two adjacent phase windings corresponding to the adjacent two phase bridge arms in the U phase winding, the V phase winding and the W phase winding. The specific functions and processing of the acquisition unit 102 are also shown in step S130.

[0108] In some implementations, the acquiring unit 102 acquires current parameters of two adjacent phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding, and the W-phase winding, including:

[0109] The acquisition unit 102 is further configured to, after applying control signals of different parameters to the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm, collect the currents flowing through the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding and the W-phase winding at the middle position of the control signals of different parameters, when the corresponding switch tubes in the adjacent two-phase bridge arms have been controlled to open, specifically, when the switch tubes of the upper bridge arm of the first phase bridge arm and the switch tubes of the lower bridge arm of the second phase bridge arm in the adjacent two-phase bridge arms are controlled to open, as the current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding and the W-phase winding.

[0110] like Figure 7As shown, in the inverter circuit, a resistor R11 is provided between the first phase bridge arm and the N end of the DC bus voltage, a resistor R12 is provided between the second phase bridge arm and the N end of the DC bus voltage, and a resistor R13 is provided between the third phase bridge arm and the N end of the DC bus voltage; a resistor R4 is provided between the P end of the DC bus voltage and the inverter circuit. In the process of realizing the fault diagnosis of the motor or the compressor, it is first necessary to collect the voltages at both ends of the P end and the N end. The voltage is the DC voltage of the DC frequency conversion, and the value of the voltage feedback is whether the power supply of the front end of the inverter module is normal. For the detection of the bus DC voltage, it is only before the detection of the motor and the compressor that it is necessary to first ensure that the power supply status of the motor controller itself is not a problem. Usually there is a working area for the bus voltage input. For example, the bus voltage is defined as Vp, and the minimum and maximum values ​​that the bus can work are Vmin and Vmax respectively, then Vmin≤Vp≤Vmax.

[0111] The implementation process of current sampling is as follows: different frequency conversion control schemes have different sampling schemes. The scheme of the present invention provides three basic sampling methods as examples. In practical applications, only one of them is needed to achieve control. The first method is to collect the current on resistor R4 to achieve single resistor sampling control; the second method is to collect the current on resistor R11, resistor R12, resistor R13 or the current on two of the resistors to achieve control; the third method is to collect current a, current b and current c flowing into the press or motor or two of the currents to achieve control of the press or motor. There is no essential difference between the three schemes. Each of them can realize the collection of current. In actual use, you can choose which method to use based on cost, reliability and other considerations.

[0112] Wherein, when the first phase bridge arm of the adjacent two-phase bridge arm is the U-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arm are the U-phase current and the V-phase current. For example: the control inverter continuously gives the control signals of the PWM signal G1 and the PWM signal G4, turns on the switch tube K1 and the switch tube K4, the given carrier frequency is 2kHz, the given duty cycle is 50%, and the current a and the current b flowing through are collected at the middle position of the control signals of the PWM signal G1 and the PWM signal G4.

[0113] In the case where the first phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the W-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arm are the V-phase current and the W-phase current. For example: the control inverter continuously gives the control signals of the PWM signal G3 and the PWM signal G6, turns on the switch tube K3 and the switch tube K6, the given carrier frequency is 2kHz, the given duty cycle is 50%, and the current b and the current c flowing through are collected at the middle position of the control signals of the PWM signal G3 and the PWM signal G6.

[0114] The scheme of the present invention realizes the control of the motor by controlling PWM signal G1, PWM signal G2, PWM signal G3, PWM signal G4, PWM signal G5 and PWM signal G6, and injects a current of a certain frequency into the motor during fault inspection, thereby obtaining the current parameters of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding and the W-phase winding, so as to detect these currents and then reversely deduce the internal parameters of the motor and the compressor, and compare the derived equivalent parameters with the specification sheet, thereby realizing rapid and accurate positioning of the cause of the motor fault.

[0115] The control unit 104 is further configured to determine the winding parameters of each phase winding in the two adjacent phase windings, specifically the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings, according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings; thereby, the winding parameters of each phase winding in the U phase winding, the V phase winding, and the W phase winding are determined, specifically the equivalent resistance and equivalent inductance of each phase winding in the U phase winding, the V phase winding, and the W phase winding are determined. The specific functions and processing of the control unit 104 are also shown in step S140.

[0116] In some embodiments, when the first phase bridge arm of the two adjacent phase bridge arms is the U phase bridge arm and the second phase bridge arm of the two adjacent phase bridge arms is the V phase bridge arm, the current parameters of the two adjacent phase windings include: U phase current and V phase current; when the first phase bridge arm of the two adjacent phase bridge arms is the V phase bridge arm and the second phase bridge arm of the two adjacent phase bridge arms is the W phase bridge arm, the current parameters of the two adjacent phase windings include: V phase current and W phase current; the winding parameters of each phase winding in the two adjacent phase windings include: equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings.

[0117] The control unit 104 determines the winding parameters of each phase winding in the two adjacent phase windings according to the DC bus voltage at the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings, including:

[0118] The control unit 104 is further configured to determine the difference between the DC bus voltage at the input side of the inverter and the back electromotive force of the motor, which is recorded as the power supply voltage difference of the motor. The specific functions and processing of the control unit 104 are also shown in step S310.

[0119] The control unit 104 is further configured to calculate the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings according to the power supply voltage difference of the motor and the corresponding relationship between the current parameters of the two adjacent phase windings as the winding parameters of each phase winding in the two adjacent phase windings. The specific functions and processing of the control unit 104 are also shown in step S320.

[0120] The current parameters of the adjacent two-phase windings include: a first group of first-phase currents and second-phase currents obtained after applying a PWM signal with a first set carrier frequency and a set duty cycle to an upper bridge arm of a first-phase bridge arm in the adjacent two-phase windings and a lower bridge arm of a second-phase bridge arm in the adjacent two-phase windings; a second group of first-phase currents and second-phase currents obtained after applying a PWM signal with a second set carrier frequency and a set duty cycle to an upper bridge arm of a first-phase bridge arm in the adjacent two-phase windings and a lower bridge arm of a second-phase bridge arm in the adjacent two-phase windings. phase current and second-phase current; the first-phase current and second-phase current of the third group obtained after applying a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings; the first-phase current and second-phase current of the fourth group obtained after applying a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings.

[0121] Specifically, in the case where the first phase bridge arm of the adjacent two-phase bridge arm is the U-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm: after applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and the V-phase current of the first group are obtained; after applying a PWM signal with a second set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and the V-phase current of the second group are obtained; after applying a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and the V-phase current of the second group are obtained. After applying a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the U-phase current and V-phase current of the fourth group are obtained; wherein, the U-phase current and V-phase current of the first group such as current a1 and b1, the U-phase current and V-phase current of the second group such as current a2 and b2, the U-phase current and V-phase current of the third group such as current a3 and b3, and the U-phase current and V-phase current of the fourth group such as current a4 and b4 are respectively the currents detected in the process of measuring the U and V phase motor parameters.

[0122] In the case where the first phase bridge arm of the adjacent two-phase bridge arm is the V-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arm is the W-phase bridge arm: after applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the first group of V-phase current and W-phase current are obtained; after applying a PWM signal with a second set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the second group of V-phase current and W-phase current are obtained; after applying a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the third group of V-phase current and W-phase current are obtained; after applying a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm, the fourth group of V-phase current and W-phase current are obtained.

[0123] The solution of the present invention determines the winding parameters of each phase of the two adjacent phase windings according to the DC bus voltage on the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings, and compares them with the specification sheet, thereby accurately locating the cause of the motor failure; the cause of the failure can be quickly located, maintenance efficiency can be improved, and after-sales maintenance costs can be reduced.

[0124] In some implementations, the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the adjacent two-phase windings includes the following formula:

[0125] Upn-e=a i *R 1i +jwL 1i *a i -b i *R 2i +jwL 2i *b i ;

[0126] Wherein, Upn-e is the power supply voltage difference of the motor, a i 、b i is the first phase current and the second phase current of the i-th group of the current parameters of the adjacent two-phase windings obtained, R 1i , L 1i is the equivalent resistance and equivalent inductance of the first phase winding in the adjacent two-phase winding, R 2i , L 2i are the equivalent resistance and equivalent inductance of the second phase winding in the adjacent two-phase windings; w=2πf, f is the different carrier frequencies in the control signals with different parameters.

[0127] Figure 8 This is a structural diagram of the equivalent circuit inside the motor. Figure 8 The equivalent circuit diagram of the compressor or motor is shown in Figure 1. The winding of each phase in the three-phase winding of the motor can be understood as a series circuit of resistance and inductance. The specific values ​​of resistance and inductance of a normal compressor or motor are within a reasonable range. Here, it is assumed that the resistance value in the compressor or motor is R±r (R is the reference value, r is the upper and lower deviation value). Since the characteristics of the three-phase winding inside the motor are basically the same in theory, it is assumed that the resistance values ​​of the other two phases are also R±r. The inductance L1 in the compressor or motor is similar to the resistance characteristics, and the inductance values ​​of the other two phases are also basically the same. Here, it is assumed that the inductance value in the compressor or motor is L±L' (L is the reference value, L' is the upper and lower deviation value). For example: the U-phase winding can be equivalent to a series structure of resistance R1 and inductance L1, the V-phase winding can be equivalent to a series structure of resistance R2 and inductance L2, and the W-phase winding can be equivalent to a series structure of resistance R3 and inductance L3.

[0128] Take the U and V ports as an example to test whether the parameters R1, R2, L1, and L2 in the motor or compressor are normal. The specific test process, i.e. the abnormal detection method of the variable frequency air conditioner compressor and motor parameters based on voltage and current parameters, includes:

[0129] Step 1: First, control the inverter to continuously give the control signals of PWM signal G1 and PWM signal G4, turn on the switch tubes K1 and K4, set the carrier frequency to 2 kHz, and set the duty cycle to 50%. At the same time, collect the current a and current b flowing through at the middle position of the control signals of PWM signal G1 and PWM signal G4, and then calculate the parameters according to the following formula (1).

[0130] Upn-e=a1*R1+jwL1*a1-b1*R2+jwL2*b1 (1).

[0131] Among them, Upn is the bus voltage at both ends of P and N; e is the motor back electromotive force at this time, and e can be calculated according to the Clark transformation (i.e. Clark transformation) and Park transformation (i.e. Park transformation) in the motor control principle, e=f(a1,b2); a1 and b1 are the currents detected during the measurement of U and V phase motor parameters; R1 and L1 are the resistance and inductance parameters of U phase in the motor and compressor; R2 and L2 are the resistance and inductance parameters of V phase in the motor and compressor.

[0132] Step 2: Repeat the above control signals and collect currents, which are a2 and b2, a3 and b3, a4 and b4 respectively. However, the subsequent carrier frequencies are 5kHz, 7kHz and 9kHz respectively, and the duty cycle given remains unchanged at 50%, thereby further providing formulas (2), (3) and (4).

[0133] Upn-e=a2*R1+jwL1*a2-b2*R2+jwL2*b2 (2);

[0134] Upn-e=a3*R1+jwL1*a3-b3*R2+jwL2*b3 (3);

[0135] Upn-e=a4*R1+jwL1*a4-b4*R2+jwL2*b4 (4).

[0136] Where Upn is the bus voltage at both ends of P and N; e is the motor back electromotive force at this time, which can be calculated based on the Clark transformation (i.e. Clark transformation) and Park transformation (i.e. Park transformation) in the motor control principle, e = f (a1, b2); refer to Figure 8, R1, L1 are the resistance and inductance parameters of the U phase in the motor and press; R2, L2 are the resistance and inductance parameters of the V phase in the motor and press; R3, L3 are the resistance and inductance parameters of the V phase in the motor and press. Current a1 and b1, current a2 and b2, current a3 and b3, and current a4 and b4 are the currents detected during the measurement of the U and V phase motor parameters. w = 2πf, where f is the carrier frequency each time, which is 2kHz, 5kHz, 7kHz, and 9kHz respectively.

[0137] Step 3: Calculate R1, R2, L1, and L2 by performing equation calculation on formula (1), formula (2), formula (3), and formula (4).

[0138] Similarly, the same control and measurement are performed on the V and W phases, and the parameters of R3 and L3 are also calculated.

[0139] The solution of the present invention determines the winding parameters of each phase of the two adjacent phase windings according to the corresponding relationship between the power supply voltage difference of the motor and the current parameters of the two adjacent phase windings, and then compares them with the specification sheet, so as to accurately locate the cause of the motor failure; it is possible to quickly locate the cause of the failure, improve maintenance efficiency, and reduce after-sales maintenance costs.

[0140] The control unit 104 is further configured to determine whether the motor is faulty according to the winding parameters of each of the U-phase winding, the V-phase winding and the W-phase winding, specifically according to the DC bus voltage at the input side of the inverter, the back electromotive force of the motor, and the equivalent resistance and equivalent inductance of each of the U-phase winding, the V-phase winding and the W-phase winding, and to determine the faulty winding of the motor when the motor is faulty, so as to detect and locate the fault of the motor. The specific functions and processing of the control unit 104 are also shown in step S150.

[0141] The scheme of the present invention provides a variable frequency air-conditioning compressor and motor parameter abnormality detection scheme based on voltage and current parameters, so that the variable frequency drive collects voltage and current parameters, and then realizes variable frequency control of the compressor or motor based on these parameters. Therefore, based on the principle of variable frequency control, the variable frequency drive fault can also be analyzed by reverse deduction with the currently collected voltage and current parameters; in this way, by applying a voltage of a certain frequency to the load control object (electric traction equipment such as a compressor or motor), and then reversely deriving the motor equivalent parameters through the motor equivalent circuit, and comparing the derived equivalent parameters with the specification sheet, the cause of the motor failure can be accurately located; the cause of the fault can be quickly located, the maintenance efficiency can be improved, the after-sales maintenance cost can be reduced, and the problem of inaccurate location of the cause of the after-sales maintenance fault can be solved; for the development of new equipment, previous fault data can be better accumulated, and subsequent development can be more targeted, the development quality can be improved, and the design deficiency of the variable frequency drive during the development of new products can be solved; customer satisfaction can be improved, and the problem of difficulty in verifying after-sales problems can be solved.

[0142] In some embodiments, the winding parameters of each of the U-phase winding, the V-phase winding and the W-phase winding include: the equivalent resistance of each of the U-phase winding, the V-phase winding and the W-phase winding, and the equivalent inductance of each phase winding.

[0143] The control unit 104 determines whether the motor fails according to the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, and determines the faulty winding of the motor when the motor fails, including:

[0144] The control unit 104 is further specifically configured to determine, for the winding parameters of each phase winding among the U-phase winding, the V-phase winding and the W-phase winding, whether a resistance error between an equivalent resistance of each phase winding among the U-phase winding, the V-phase winding and the W-phase winding and a preset standard resistance is within a set resistance error range, and an inductance error between an equivalent inductance of each phase winding among the U-phase winding, the V-phase winding and the W-phase winding and a preset standard inductance is within a set inductance error range.

[0145] The control unit 104 is further specifically configured to determine that the motor has no fault if the condition is satisfied.

[0146] The control unit 104 is further specifically configured to determine that the motor is faulty and the faulty resistance of the motor is a corresponding phase winding whose resistance error is not within a set resistance error range and / or whose inductance error is not within a set inductance error range if the condition is not satisfied.

[0147] In the scheme of the present invention, the method for detecting abnormal parameters of the compressor and motor of the variable frequency air conditioner based on voltage and current parameters also includes: comparing the calculated R1, R2, and R3 with the standard value R±r in turn: if it exceeds the range value, it is considered abnormal; if it is within the standard value, the resistance value is considered normal. Similarly, the inductance L1, L2, and L3 are compared with the standard value L±L'. If the resistance value and the inductance value are both within the standard value, the compressor or motor is considered normal. If any value is unexpected from the standard value, the compressor or motor is considered abnormal. By calculating the electrical parameters inside the motor and the compressor, the whole machine checks whether the inductance value inside the motor is abnormal. If it is abnormal, the motor is directly determined to be abnormal without replacing other parts of the unit.

[0148] The solution of the present invention provides a method for identifying abnormal parameters of a press and motor based on voltage and current sampling parameters and by calculating through a variable frequency drive algorithm, so as to more accurately locate the type of press and motor faults. That is to say, the solution of the present invention, based on the control principle of the press and motor, reversely deduce the press and motor parameters according to the collected voltage and current, to realize the identification of the parameters of the press and motor body, so as to determine whether the press and motor are faulty, and accurately locate the type of fault and parameter of the motor internal fault. In the solution of the present invention, a method of actively detecting the parameters of the press and motor is adopted, which solves the problem of inaccurate positioning of the press and fan faults in the previous fault unit faults, can quickly locate the cause of the fault, improve maintenance efficiency, and reduce after-sales maintenance costs. In the solution of the present invention, active detection of the parameters of the press and motor is adopted, which further refines the fault type and solves the problem of inaccurate fault feedback, so that subsequent fault personnel and developers can better obtain accurate fault data, so that in the subsequent development of new products, they can better refer to the previous fault data, solve the basic platform problems in a targeted manner, and develop better products. In the solution of the present invention, accurate positioning of press and motor faults is adopted, which solves the problem that the customer's group cannot be repaired for a long time after the fault, thereby improving customer satisfaction.

[0149] Since the processing and functions implemented by the device of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, 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.

[0150] According to an embodiment of the present invention, a frequency conversion unit corresponding to the fault determination device of the frequency conversion unit is also provided. The frequency conversion unit may include: the fault determination device of the frequency conversion unit described above.

[0151] Since the processing and functions implemented by the frequency conversion unit of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned device, 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.

[0152] According to an embodiment of the present invention, a computer program product corresponding to a variable frequency machine set is also provided, comprising a computer program, which implements the steps of the variable frequency machine set fault determination method described above when executed by a processor.

[0153] Since the processing and functions implemented by the product of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned frequency conversion unit, 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.

[0154] According to an embodiment of the present invention, a storage medium corresponding to the fault determination method of the variable frequency unit is also provided, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the fault determination method of the variable frequency unit described above.

[0155] Since the processing and functions implemented by the storage medium of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, 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.

[0156] 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.

[0157] 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 method for determining a fault of a frequency conversion unit, characterized in that: The load of the frequency conversion unit has a motor, and the motor has a U-phase winding, a V-phase winding, and a W-phase winding; the inverter of the motor includes: a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, and a sixth switch tube, the first switch tube and the second switch tube are connected in series up and down to form a U-phase bridge arm, the third switch tube and the fourth switch tube are connected in series up and down to form a V-phase bridge arm, and the fifth switch tube and the sixth switch tube are connected in series up and down to form a W-phase bridge arm; the fault determination method of the frequency conversion unit includes: Obtaining a DC bus voltage at an input side of the inverter and obtaining a back electromotive force of the motor; Applying control signals with different parameters to two adjacent bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm; Acquire current parameters of two adjacent phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding and the W-phase winding; Determine the winding parameters of each phase winding in the two adjacent phase windings according to the DC bus voltage at the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings; thereby determine the winding parameters of each phase winding in the U phase winding, the V phase winding, and the W phase winding; According to the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, it is determined whether the motor is faulty, and when the motor is faulty, the faulty winding of the motor is determined, so as to realize fault detection and positioning of the motor.

2. The method for determining a fault of a frequency conversion unit according to claim 1, characterized in that: The control signals with different parameters include: PWM signals with different carrier frequencies and the same duty cycle; the adjacent two-phase bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm include: the adjacent two-phase bridge arms with the U-phase bridge arm as the first phase bridge arm and the V-phase bridge arm as the second phase bridge arm, and / or the adjacent two-phase bridge arms with the V-phase bridge arm as the first phase bridge arm and the W-phase bridge arm as the second phase bridge arm; Applying control signals with different parameters to two adjacent bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm comprises: Applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to turn on; After a set time interval, a PWM signal with a second set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to turn on; wherein the second set carrier frequency is greater than the first set carrier frequency; After a set time interval, a PWM signal with a third set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to turn on; wherein the third set carrier frequency is greater than the second set carrier frequency; After a set time interval, a PWM signal with a fourth set carrier frequency and a set duty cycle is applied to the upper bridge arm of the first phase bridge arm and the lower bridge arm of the second phase bridge arm to control the switch tube of the upper bridge arm of the first phase bridge arm and the switch tube of the lower bridge arm of the second phase bridge arm to open; wherein the fourth set carrier frequency is greater than the third set carrier frequency.

3. The method for determining a fault of a frequency conversion unit according to claim 1 or 2, characterized in that: Obtaining current parameters of two adjacent phase windings corresponding to the adjacent two-phase bridge arms in the U-phase winding, the V-phase winding, and the W-phase winding, including: After applying control signals of different parameters to two adjacent bridge arms among the U-phase bridge arm, the V-phase bridge arm, and the W-phase bridge arm, when the corresponding switch tubes in the adjacent two bridge arms have been controlled to be turned on, at the middle position of the control signals of different parameters, collecting the currents flowing through the adjacent two windings corresponding to the adjacent two bridge arms among the U-phase winding, the V-phase winding, and the W-phase winding as the current parameters of the adjacent two windings corresponding to the adjacent two bridge arms among the U-phase winding, the V-phase winding, and the W-phase winding; in, When the first phase bridge arm of the adjacent two-phase bridge arms is the U-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arms is the V-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms are the U-phase current and the V-phase current; When the first phase bridge arm of the adjacent two-phase bridge arms is the V-phase bridge arm and the second phase bridge arm of the adjacent two-phase bridge arms is the W-phase bridge arm, the currents of the adjacent two-phase windings corresponding to the adjacent two-phase bridge arms are the V-phase current and the W-phase current.

4. The method for determining a fault of a frequency conversion unit according to any one of claims 1 to 3, characterized in that: The winding parameters of each phase winding in the two adjacent phase windings include: the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings; Determining winding parameters of each phase winding in the two adjacent phase windings according to the DC bus voltage at the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings, including: Determine the difference between the DC bus voltage at the input side of the inverter and the back electromotive force of the motor, and record it as the power supply voltage difference of the motor; According to the power supply voltage difference of the motor and the corresponding relationship between the current parameters of the two adjacent phase windings, the equivalent resistance and equivalent inductance of each phase winding in the two adjacent phase windings are calculated as the winding parameters of each phase winding in the two adjacent phase windings; The current parameters of the adjacent two-phase windings include: The first phase current and the second phase current of the first group are obtained after applying a PWM signal with a first set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings; the first phase current and the second phase current of the second group are obtained after applying a PWM signal with a second set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings; the first phase current and the second phase current of the third group are obtained after applying a PWM signal with a third set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings; the first phase current and the second phase current of the fourth group are obtained after applying a PWM signal with a fourth set carrier frequency and a set duty cycle to the upper bridge arm of the first phase bridge arm in the two adjacent phase windings and the lower bridge arm of the second phase bridge arm in the two adjacent phase windings.

5. The method for determining the fault of a frequency conversion unit according to claim 4, characterized in that: The corresponding relationship between the power supply voltage difference of the motor and the current parameters of the adjacent two-phase windings includes the following formula: Upn-e=a i *R 1i +jwL 1i *a i -b i *R 2i +jwL 2i *b i ; Wherein, Upn-e is the power supply voltage difference of the motor, a i 、b i is the first phase current and the second phase current of the i-th group of the current parameters of the adjacent two-phase windings obtained, R 1i , L 1i is the equivalent resistance and equivalent inductance of the first phase winding in the adjacent two-phase winding, R 2i , L 2i are the equivalent resistance and equivalent inductance of the second phase winding in the adjacent two-phase windings; w=2πf, f is the different carrier frequencies in the control signals with different parameters.

6. The method for determining a fault of a frequency conversion unit according to any one of claims 1 to 5, characterized in that: The winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding include: the equivalent resistance of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, and the equivalent inductance of each phase winding; Determining whether the motor fails according to winding parameters of each phase winding of the U-phase winding, the V-phase winding, and the W-phase winding, and determining a faulty winding of the motor when the motor fails, includes: For the winding parameters of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding, determine whether a resistance error between an equivalent resistance of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding and a preset standard resistance is within a set resistance error range, and an inductance error between an equivalent inductance of each phase winding of the U-phase winding, the V-phase winding and the W-phase winding and a preset standard inductance is within a set inductance error range; If it is determined that the condition is satisfied, it is determined that the motor has no fault; If it is determined that it is not satisfied, it is determined that the motor is faulty and the faulty resistance of the motor is a corresponding phase winding whose resistance error is not within a set resistance error range and / or whose inductance error is not within a set inductance error range.

7. A fault determination device for a frequency conversion unit, characterized in that: The load of the frequency conversion unit has a motor, and the motor has a U-phase winding, a V-phase winding and a W-phase winding; the inverter of the motor includes: a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube and a sixth switch tube, the first switch tube and the second switch tube are connected in series up and down to form a U-phase bridge arm, the third switch tube and the fourth switch tube are connected in series up and down to form a V-phase bridge arm, and the fifth switch tube and the sixth switch tube are connected in series up and down to form a W-phase bridge arm; the fault determination device of the frequency conversion unit includes: an acquisition unit, configured to acquire a DC bus voltage at an input side of the inverter and acquire a back electromotive force of the motor; A control unit is configured to apply control signals with different parameters to two adjacent bridge arms among the U-phase bridge arm, the V-phase bridge arm and the W-phase bridge arm; The acquisition unit is further configured to acquire current parameters of two adjacent phase windings corresponding to the adjacent two-phase bridge arms among the U-phase winding, the V-phase winding and the W-phase winding; The control unit is further configured to determine the winding parameters of each phase winding in the two adjacent phase windings according to the DC bus voltage at the input side of the inverter, the back electromotive force of the motor, and the current parameters of the two adjacent phase windings; thereby determining the winding parameters of each phase winding in the U phase winding, the V phase winding, and the W phase winding; The control unit is also configured to determine whether the motor is faulty based on the winding parameters of each phase winding in the U-phase winding, the V-phase winding and the W-phase winding, and to determine the faulty winding of the motor when the motor is faulty, so as to realize fault detection and positioning of the motor.

8. A frequency conversion unit, characterized in that: include: The fault determination device of the frequency conversion unit as claimed in claim 7.

9. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the method for determining a fault of a frequency conversion unit according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for determining a fault of a frequency conversion unit according to any one of claims 1 to 6 are implemented.

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