Motor and protection method and device thereof, storage medium and computer program product

Abstract

The invention discloses a motor protection method and device, a motor, a storage medium and a computer program product, and the method comprises the steps: obtaining the phase current of each phase winding of the motor for each phase winding of three-phase windings of the motor in the operation process of the motor; therefore, the three-phase current of the motor is obtained. Only according to the three-phase current of the motor, in combination with a preset fault retrieval subprogram, determining whether one phase of current in the three-phase current of the motor is lack of phase; and under the condition that it is determined that one of the three-phase currents of the motor is open in phase, a reminding message that one of the three-phase currents of the motor is open in phase is initiated, and the motor is controlled to stop, so that open-phase protection of the motor is achieved. According to the scheme, the open-phase protection is carried out only based on the three-phase current of the motor without depending on the rotor angle of the motor, so that the reliability of the open-phase protection of the motor is improved.

Description

Technical Field

[0001] The present invention belongs to the field of motor technology, and specifically relates to a method, device, motor, storage medium and computer program product for protecting a motor (such as a permanent magnet synchronous motor), and in particular to a method, device, motor, storage medium and computer program product for protecting a motor (such as a permanent magnet synchronous motor) that is independent of the rotor angle of the motor. Background Art

[0002] Electric motors are widely used as power sources in applications such as fans, aerators, and electric vehicles. Permanent magnet synchronous motors, as a type of electric motor, use the magnetic interaction between the magnetic field generated by the coil through which current flows and the magnetic field generated by the permanent magnets to rotate the rotor. With the mature development of home appliance technology and the rapid advancement of power electronics technology, permanent magnet synchronous motors are becoming more and more popular due to their low cost, high efficiency, and low noise. Permanent magnet synchronous motors have a phase loss protection mechanism, but the phase loss protection mechanism of permanent magnet synchronous motors in related solutions requires reading the rotor angle of the motor. When the calculated rotor angle differs from the actual angle, the phase loss protection will fail.

[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 motor protection method, device, motor, storage medium and computer program product to solve the problem that the phase loss protection mechanism of the permanent magnet synchronous motor in the related scheme needs to read the rotor angle of the motor, and when the calculated rotor angle is different from the actual angle, the phase loss protection will become invalid. The effect of improving the reliability of the phase loss protection of the motor is achieved by performing phase loss protection based only on the three-phase current of the motor without relying on the rotor angle of the motor.

[0005] The present invention provides a motor protection method, wherein the motor has a three-phase winding; the motor protection method comprises: during the operation of the motor, for each phase winding of the three-phase winding of the motor, obtaining the phase current of each phase winding of the motor; thereby obtaining the three-phase current of the motor; determining whether one phase of the three-phase current of the motor is phase-deficient only based on the three-phase current of the motor and in combination with a preset fault retrieval subroutine; and, in the case of determining that the one phase of the three-phase current of the motor is phase-deficient, initiating a reminder message that the one phase of the three-phase current of the motor is phase-deficient, and controlling the motor to stop, so as to achieve phase-deficient protection for the motor.

[0006] In some embodiments, only based on the three-phase current of the motor, combined with a preset fault retrieval subroutine, it is determined whether one phase of the three-phase current of the motor is missing, including: determining whether the current current cycle is over; if it is determined that the current current cycle is not over, then within the current cycle, for each phase of the three-phase current of the motor, the absolute value of the accumulated value of each phase current of the full current cycle, the absolute value of the accumulated value of each phase current of the positive half current cycle, and the absolute value of the accumulated value of each phase current of the negative half current cycle are calculated, and then return to re-determine the current current cycle Whether it is ended; thereby, in the current current cycle, the absolute value of the accumulated three-phase current of the full current cycle, the absolute value of the accumulated three-phase current of the positive half current cycle, and the absolute value of the accumulated three-phase current of the negative half current cycle are obtained; if it is determined that the current current cycle is over, the preset fault retrieval subroutine is executed to combine the absolute value of the accumulated three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated three-phase current of the positive half current cycle, and the absolute value of the accumulated three-phase current of the negative half current cycle to determine whether one phase of the three-phase current of the motor is missing.

[0007] In some embodiments, the current cycle includes: a positive half-current cycle and a negative half-current cycle; wherein the positive half-current cycle and the negative half-current cycle constitute a full current cycle; within the current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated current of each phase of the full current cycle, the absolute value of the accumulated current of each phase of the positive half-current cycle, and the absolute value of the accumulated current of each phase of the negative half-current cycle are calculated, including: within the current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated current of each phase obtained at the current moment is calculated. After taking the absolute value of the current, the absolute value of the accumulated current of each phase is added to the full current cycle; determine whether the current moment belongs to the positive half-current cycle of the current current cycle; if it is determined that the current moment belongs to the positive half-current cycle of the current current cycle, then after taking the absolute value of the current of each phase obtained at the current moment, the accumulated current is added to the absolute value of the accumulated current of each phase in the positive half-current cycle; if it is determined that the current moment does not belong to the positive half-current cycle of the current current cycle, then after taking the absolute value of the current of each phase obtained at the current moment, the accumulated current is added to the absolute value of the accumulated current of each phase in the negative half-current cycle.

[0008] In some embodiments, for one phase current of the three-phase current of the motor, the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle are taken, including: the absolute value of the accumulated value of the one-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the one-phase current of the positive half current cycle, and the absolute value of the accumulated value of the one-phase current of the negative half current cycle are taken; executing a preset fault retrieval subroutine to combine the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle to determine whether one phase current of the three-phase current of the motor is missing, including: Execute a preset fault retrieval subroutine to determine whether one of the three-phase currents of the motor satisfies at least one of the following conditions within the current cycle: the absolute value of the accumulated value of the current of the phase in the positive half-current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the negative half-current cycle to a set coefficient, the absolute value of the accumulated value of the current of the phase in the negative half-current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the positive half-current cycle to a set coefficient, and the absolute value of the accumulated value of the current of the phase in the full current cycle is less than the ratio of the sum of the absolute values ​​of the accumulated values ​​of the other two phases in the full current cycle to a set coefficient; wherein the set coefficient is greater than 1; according to the determination result, adjust the preset cumulative fault count value; and according to the adjusted preset cumulative fault count value, determine whether the current of the phase in the three-phase current of the motor is missing.

[0009] In some embodiments, the determination result is: determined not satisfied, or determined satisfied; according to the determination result, adjusting the preset cumulative fault count value; and determining whether the one-phase current in the three-phase current of the motor is missing a phase according to the adjusted preset cumulative fault count value, including: determining whether the determination result is determined not satisfied or determined satisfied; if the determination result is determined not satisfied, then when the preset cumulative fault count value is equal to 0, directly return to re-execute the preset fault retrieval subroutine; when the preset cumulative fault count value is greater than 0, reduce the preset cumulative fault count value by 1, and then return to re-execute the preset fault retrieval subroutine; if the determination result is determined satisfied, then the preset cumulative fault count value is increased by 1; then, according to the adjusted preset cumulative fault count value, determine whether the one-phase current in the three-phase current of the motor is missing a phase.

[0010] In some embodiments, determining whether one phase of the three-phase current of the motor is lacking in phase is based on an adjusted preset cumulative fault count value, including: determining whether the adjusted preset cumulative fault count value is greater than a set number of times; if it is determined that the adjusted preset cumulative fault count value is not greater than the set number of times, returning to re-execute the preset fault retrieval subroutine; if it is determined that the adjusted preset cumulative fault count value is greater than the set number of times, determining that one phase of the three-phase current of the motor is lacking in phase.

[0011] Matching the above method, the present invention provides a motor protection device on the other hand, wherein the motor has a three-phase winding; the motor protection device comprises: an acquisition unit, configured to acquire the phase current of each phase winding of the motor for each phase winding of the three-phase winding of the motor during the operation of the motor; thereby, the three-phase current of the motor is obtained; a control unit, configured to determine whether one phase of the three-phase current of the motor is missing based only on the three-phase current of the motor and in combination with a preset fault retrieval subroutine; and the control unit is also configured to, when it is determined that the one phase of the three-phase current of the motor is missing, initiate a reminder message of the missing phase of the one phase of the three-phase current of the motor and control the motor to stop, so as to achieve phase-missing protection for the motor.

[0012] In some embodiments, the control unit determines whether one phase of the three-phase current of the motor is missing based only on the three-phase current of the motor in combination with a preset fault retrieval subroutine, including: determining whether the current current cycle is over; if it is determined that the current current cycle is not over, then within the current current cycle, for each phase current of the three-phase current of the motor, calculate the absolute value of the accumulated value of each phase current of the full current cycle, the absolute value of the accumulated value of each phase current of the positive half current cycle, and the absolute value of the accumulated value of each phase current of the negative half current cycle, and then return to re-determine the current current cycle. whether the current cycle is over; thereby, in the current current cycle, the absolute value of the accumulated three-phase current of the full current cycle, the absolute value of the accumulated three-phase current of the positive half current cycle, and the absolute value of the accumulated three-phase current of the negative half current cycle are obtained; if it is determined that the current current cycle is over, the preset fault retrieval subroutine is executed to combine the absolute value of the accumulated three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated three-phase current of the positive half current cycle, and the absolute value of the accumulated three-phase current of the negative half current cycle to determine whether one phase of the three-phase current of the motor is missing.

[0013] In some embodiments, the current cycle includes: a positive half-current cycle and a negative half-current cycle; wherein the positive half-current cycle and the negative half-current cycle constitute a full current cycle; the control unit, in the current cycle, for each phase current of the three-phase current of the motor, calculates the absolute value of the accumulated current of each phase of the full current cycle, the absolute value of the accumulated current of each phase of the positive half-current cycle, and the absolute value of the accumulated current of each phase of the negative half-current cycle, including: in the current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated current of each phase of the full current cycle, the absolute value of the accumulated current of each phase of the positive half-current cycle, and the absolute value of the accumulated current of each phase of the negative half-current cycle. After taking the absolute value of each phase current, the absolute value of the accumulated value of each phase current in the full current cycle is accumulated and counted; determine whether the current moment belongs to the positive half-current cycle of the current current cycle; if it is determined that the current moment belongs to the positive half-current cycle of the current current cycle, then after taking the absolute value of each phase current obtained at the current moment, the absolute value of the accumulated value of each phase current is accumulated and counted in the positive half-current cycle; if it is determined that the current moment does not belong to the positive half-current cycle of the current current cycle, then after taking the absolute value of each phase current obtained at the current moment, the absolute value of the accumulated value of each phase current is accumulated and counted in the negative half-current cycle.

[0014] In some embodiments, for one-phase current of the three-phase current of the motor, the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle are taken, including: the absolute value of the accumulated value of one-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of one-phase current of the positive half current cycle, and the absolute value of the accumulated value of one-phase current of the negative half current cycle are taken; the control unit executes a preset fault retrieval subroutine to determine whether one-phase current of the three-phase current of the motor is missing in combination with the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle. , including: executing a preset fault retrieval subroutine to determine whether one of the three-phase current of the motor satisfies at least one of the following conditions within the current cycle: the absolute value of the accumulated value of the current of the phase in the positive half current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the negative half current cycle to a set coefficient, the absolute value of the accumulated value of the current of the phase in the negative half current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the positive half current cycle to a set coefficient, and the absolute value of the accumulated value of the current of the phase in the full current cycle is less than the ratio of the sum of the absolute values ​​of the accumulated values ​​of the other two phases in the full current cycle to a set coefficient; wherein the set coefficient is greater than 1; according to the determination result, adjusting the preset cumulative fault count value; and according to the adjusted preset cumulative fault count value, determining whether the current of the phase in the three-phase current of the motor is missing.

[0015] In some embodiments, the determination result is: determined not satisfied, or determined satisfied; the control unit adjusts the preset cumulative fault count value according to the determination result; and determines whether the one-phase current in the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value, including: determining whether the determination result is determined not satisfied or determined satisfied; if the determination result is determined not satisfied, then when the preset cumulative fault count value is equal to 0, directly return to re-execute the preset fault retrieval subroutine; when the preset cumulative fault count value is greater than 0, reduce the preset cumulative fault count value by 1, and then return to re-execute the preset fault retrieval subroutine; if the determination result is determined satisfied, the preset cumulative fault count value is increased by 1; then, according to the adjusted preset cumulative fault count value, determine whether the one-phase current in the three-phase current of the motor is missing.

[0016] In some embodiments, the control unit determines whether one phase of the three-phase current of the motor is lacking in phase based on the adjusted preset cumulative fault count value, including: determining whether the adjusted preset cumulative fault count value is greater than the set number of times; if it is determined that the adjusted preset cumulative fault count value is not greater than the set number of times, returning to re-execute the preset fault retrieval subroutine; if it is determined that the adjusted preset cumulative fault count value is greater than the set number of times, determining that one phase of the three-phase current of the motor is lacking in phase.

[0017] Matching the above device, the present invention further provides a motor, including: the motor protection device described above.

[0018] In accordance with the above method, the present invention provides a storage medium on another aspect, wherein 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 steps of the motor protection method described above.

[0019] In accordance with the above method, the present invention provides a computer program product on another aspect, including a computer program, which implements the steps of the motor protection method described above when executed by a processor.

[0020] Therefore, the scheme of the present invention obtains the three-phase current of the motor according to the set current cycle when executing the phase loss protection mechanism of the motor (such as a permanent magnet synchronous motor); when a current current cycle has not ended, for each phase current of the three-phase current of the motor, the absolute value of the accumulated value of each phase current of the full current cycle of the motor, the absolute value of the accumulated value of each phase current of the positive half current cycle, and the absolute value of the accumulated value of each phase current of the negative half current cycle are calculated within one current cycle; when a current current cycle ends, a preset fault retrieval subroutine is entered, and for each phase current of the three-phase current of the motor, the accumulated fault count value of each phase current is increased and decreased according to three judgment conditions, and the phase loss protection is triggered when the accumulated fault count value of each phase current reaches a certain number; thereby, the reliability of the phase loss protection of the motor is improved by performing phase loss protection based only on the three-phase current of the motor without relying on the rotor angle of the motor.

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

[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 diagram of a flow chart of an embodiment of a motor protection method of the present invention;

[0024] Figure 2 It is a flow chart of an embodiment of the method of the present invention for determining whether one phase of the three-phase current of the motor is missing only according to the three-phase current of the motor;

[0025] Figure 3 A flow chart of an embodiment of calculating the absolute value of the accumulated current value of each phase in a full current cycle, the absolute value of the accumulated current value of each phase in a positive half current cycle, and the absolute value of the accumulated current value of each phase in a negative half current cycle 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 one phase of the three-phase current of the motor is missing by combining the absolute value of the accumulated value of the three-phase current of the full current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle;

[0027] Figure 5 It is a flow chart of an embodiment of determining whether one phase of the three-phase current of the motor is missing according to the determination result in the method of the present invention;

[0028] Figure 6A flow chart of an embodiment of determining whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value in the method of the present invention;

[0029] Figure 7 It is a structural schematic diagram of an embodiment of a motor protection device of the present invention;

[0030] Figure 8 It is a structural schematic diagram of an embodiment of a permanent magnet synchronous motor phase loss protection system;

[0031] Fig. 9 It is a curve diagram of the electrical angle (Theta) and the phase current I in the phase loss protection detection method in the relevant scheme, wherein Figure ① is a schematic diagram of the phase current waveform of any phase when the permanent magnet synchronous motor is operating normally, and Figure ② is a schematic diagram of the possible phase current waveform when the permanent magnet synchronous motor has a phase loss situation;

[0032] Fig.10 Schematic diagram of the curve of the electrical angle (Theta) and the phase current I in the phase loss protection detection method of the present invention, wherein Figure ① is a schematic diagram of the phase current waveform of any phase when the permanent magnet synchronous motor is operating normally, Figure ② is a schematic diagram of the waveform after taking the absolute value of the current waveform in Figure ①, Figure ③ is a schematic diagram of the absolute value of the possible phase current waveform 1 when the permanent magnet synchronous motor has a phase loss, and Figure ④ is a schematic diagram of the absolute value of the possible phase current waveform 2 when the permanent magnet synchronous motor has a phase loss;

[0033] Fig.11 It is a flow chart of the main program of the phase-loss protection in the phase-loss protection detection method of the present invention;

[0034] Fig.12 It is a flow chart of the U-phase failure fault retrieval subroutine in the phase failure protection detection method of the present invention.

[0035] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0036] [1]-Permanent magnet synchronous motor; [2]-Main control chip; [3]-Power device IPM module; [4]-Current sampling circuit; [5]-Phase loss protection detection module; 102-Acquisition unit; 104-Control unit. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] Considering that in the relevant scheme, the motor controller of the motor (such as a permanent magnet synchronous motor) needs to read the rotor angle of the motor to implement the phase loss protection function, when the calculated rotor angle is different from the actual angle, the phase loss protection will fail. Specifically, the phase loss protection mechanism in the relevant scheme can be: by setting a current threshold, taking the absolute value of the read phase current value and then comparing it with the set current threshold; if the absolute value of the phase current value read at this moment is greater than the current threshold, then record the electrical angle at this moment; after the analysis cycle ends, calculate the electrical angle range of the phase current value in half a current cycle that is greater than the current threshold; then determine whether this part occupies more than 2 / 3 of the entire current half cycle, if the result is otherwise, determine that the motor is phase-lost. The essential reason for the failure of the phase loss protection mechanism in the relevant scheme is that when there is a difference between the calculated rotor angle and the actual angle, the recorded electrical angle has an error with the actual electrical angle at that moment, resulting in the judgment of the electrical angle range not being consistent with the actual situation, resulting in a misjudgment that makes the phase loss protection fail or the protection mistriggered.

[0039] For example: take half a current cycle as an analysis cycle, set a current threshold, take the absolute value of the read phase current value and compare it with the set current threshold; if the absolute value of the phase current value read at this moment is greater than the current threshold, then record the electrical angle at that moment; after the analysis cycle is over, calculate the electrical angle range of the part where the absolute value of the phase current value in half a current cycle is greater than the current threshold; then determine whether this part occupies more than 2 / 3 of the entire current half cycle, if the result is not, determine that the motor is out of phase. However, the disadvantage of this method is that it is necessary to read the rotor angle of the motor to calculate the electrical angle. When there is a difference between the calculated rotor angle and the actual angle, there is a situation of protection failure or false triggering. At the same time, the selection of the current threshold will also affect the reliability of the phase loss protection.

[0040] It can be seen that the implementation of the phase loss protection mechanism in the relevant scheme depends on the rotor angle of the motor. When there is a difference between the calculated rotor angle and the actual angle, it will also affect the implementation of the phase loss protection function. There is a problem that the phase loss protection mechanism of the permanent magnet synchronous motor fails during operation; in addition, the phase loss protection mechanism of the permanent magnet synchronous motor has problems such as failure of phase loss protection during motor operation and false triggering of protection during motor operation due to current sampling interference. In other words, the phase loss protection mechanism of the permanent magnet synchronous motor in the relevant scheme has problems such as failure of phase loss protection during operation and false triggering of protection during motor operation due to current sampling interference; at the same time, the implementation of the phase loss protection mechanism in the relevant scheme depends on the rotor angle of the motor. When there is a difference between the calculated rotor angle and the actual angle, it will also affect the implementation of the phase loss protection function.

[0041] Therefore, the scheme of the present invention proposes a protection method for a motor (such as a permanent magnet synchronous motor), specifically a phase loss protection method for a motor (such as a permanent magnet synchronous motor) that is independent of the rotor angle of the motor. It does not need to read the rotor angle of the motor, and determines whether a phase loss occurs by comparing the accumulated value of the absolute values ​​of the phase currents in the positive and negative half cycles within a current cycle, thereby effectively improving the reliability of the phase loss protection of the motor.

[0042] According to an embodiment of the present invention, a method for protecting a motor is provided, such as Figure 1 The motor has three-phase windings, such as a U-phase winding, a V-phase winding and a W-phase winding; in the solution of the present invention, Figure 1 As shown, the motor protection method includes: steps S110 to S130.

[0043] At step S110, when the phase loss protection mechanism of the motor is enabled, during the operation of the motor, the phase current of each phase winding of the motor is obtained for each phase winding of the three-phase winding of the motor, that is, the phase current of each phase winding of the three-phase winding of the motor is obtained; thereby, the three-phase current of the motor is obtained. When the phase current of each phase winding of the three-phase winding of the motor is obtained, it can be obtained at a set sampling period or in real time.

[0044] In step S120, only based on the three-phase current of the motor, combined with a preset fault search subroutine, it is determined whether one phase of the three-phase current of the motor is missing. And,

[0045] At step S130, when it is determined that one phase of the three-phase current of the motor is missing, a reminder message of the missing phase of the three-phase current of the motor is initiated, and the motor is controlled to stop to achieve phase-missing protection for the motor.

[0046] Figure 8 FIG. 1 is a schematic diagram of the structure of an embodiment of a permanent magnet synchronous motor phase loss protection system. Figure 8As shown, the permanent magnet synchronous motor phase loss protection system includes: a permanent magnet synchronous motor [1], a main control chip [2], a power device IPM module [3], a current sampling circuit [4] and a phase loss protection detection module [5]. The power device IPM module [3] is connected between the pulse width modulation (PWM) signal output end of the main control chip [2] and the three-phase phase line of the permanent magnet synchronous motor [1]. The current sampling circuit [4] and the phase loss protection detection module [5] are connected in sequence between the three-phase winding of the permanent magnet synchronous motor [1] and the input end of the main control chip [2]. Among them, the power device IPM module [3] is an intelligent power module (Intelligent Power Module, IPM).

[0047] The main control chip [2] is used to receive the fault signal from the phase loss protection detection module [5], and control the operation and shutdown of the power device IPM module [3] by opening and closing the output of the six-way PWM signal; the power device IPM module [3] is used to receive the six-way PWM signal output from the main control chip [2], and generate a sinusoidal current to drive the permanent magnet synchronous motor [1] to operate by opening and closing the upper and lower bridge IGBTs; the current sampling circuit [4] is used to collect the current flowing through the three-phase winding of the permanent magnet synchronous motor [1], and input the collected current value to the phase loss protection detection module [5]; the phase loss protection detection module [5] is used to analyze the three-phase current value collected by the current sampling circuit [4], and when any phase of the three phases of the motor is missing, trigger the motor controller to perform phase loss protection, and output a fault signal to the main control chip [2].

[0048] See also Figure 8 In the example shown, the present invention provides a permanent magnet synchronous motor phase loss protection scheme that does not require reading the rotor angle of the motor. The main control chip [2] outputs a three-phase complementary PWM signal to the power device IPM module [3]. The power device IPM module [3] drives the motor to run. When the motor is running, the current on the three-phase line is collected by the sampling circuit to the phase loss protection detection module. When the program determines that any phase is missing, the detection module outputs a fault signal to the main control chip [2].

[0049] Fig. 9 Figure 1 is a schematic diagram of the curve of the electrical angle (Theta) and the phase current I in the phase loss protection detection method in the relevant scheme, wherein Figure 1 is a schematic diagram of the phase current waveform of any phase when the permanent magnet synchronous motor is operating normally, and Figure 2 is a schematic diagram of the possible phase current waveform when the permanent magnet synchronous motor has a phase loss. Fig. 9 As shown, half a current cycle is taken as an analysis cycle. Fig. 9Figure ① is a schematic diagram of the phase current waveform of any phase when the permanent magnet synchronous motor is operating normally. In the entire analysis cycle, it is necessary to first select a current threshold value, which is used to compare with the actual sampled current value, and divide the current waveform of the entire half cycle into two parts, the upper and lower parts. The electrical angle range of the current waveform greater than the threshold is as follows: Fig. 9 As shown in Figure ①, it is: θ2-θ1. When the motor is running normally and there is no phase loss, the θ2-θ1 part will occupy more than 2 / 3 of the entire current half cycle, that is, θ2-θ1>120°.

[0050] Fig. 9 Figure ② is a schematic diagram of the possible phase current waveform when the permanent magnet synchronous motor is missing a phase. The entire waveform is also divided into two parts, the part greater than the current threshold, such as Fig. 9 As shown in Figure ②, it is: θ2-θ1, θ4-θ3, θ6-θ5; θ1, θ2, θ3, θ4, θ5, θ6 are all the rotor angles of the motor, that is, the electrical angles. Among them, θ2-θ1 represents the angle range from θ2 to θ1, θ4-θ3 represents the angle range from θ4 to θ3, and θ6-θ5 represents the angle range from θ6 to θ5. At this time, the sum of the angle ranges corresponding to all parts greater than the current threshold will be less than 120°, indicating that at this time, the effective value of one phase current is less than the normal range. At this time, it is judged that the motor is out of phase. The phase loss protection mechanism in the relevant scheme needs to detect the motor phase current and the rotor angle of the motor at the same time, and the implementation depends on the rotor angle of the motor. When there is a difference between the calculated rotor angle and the actual angle, there is also an error between the electrical angle recorded by the program and the actual electrical angle at that moment, resulting in the judgment of the electrical angle range not being consistent with the actual situation, and the misjudgment makes the phase loss protection invalid or the protection mistriggered.

[0051] Compared with the solution of the present invention, the related solutions all need to detect the motor phase current, and the phase current value read is used for calculation to determine whether the motor has a phase loss. However, the related solutions need to detect the motor phase current and the motor rotor angle at the same time, and determine whether a phase loss occurs by calculating the electrical angle range that exceeds the current threshold. The judgment result is affected by the rotor angle calculated by the program. The solution of the present invention only needs to detect the motor phase current, and can determine whether the motor has a phase loss by calculation, and the protection reliability is higher.

[0052] Fig.10 The diagram is a curve diagram of the electrical angle (Theta) and the phase current I in the phase loss protection detection method of the present invention, wherein Figure 1 is a waveform diagram of the phase current of any phase when the permanent magnet synchronous motor is operating normally, Figure 2 is a waveform diagram after taking the absolute value of the current waveform of Figure 1, Figure 3 is a diagram of the absolute value of the possible phase current waveform 1 when the permanent magnet synchronous motor has a phase loss, and Figure 4 is a diagram of the absolute value of the possible phase current waveform 2 when the permanent magnet synchronous motor has a phase loss. Fig.10 As shown, the entire current cycle is taken as one analysis cycle. Fig.10 Figure ① in the middle is a schematic diagram of the phase current waveform of any phase during normal operation of the permanent magnet synchronous motor. The entire waveform is divided into a positive half-cycle and a negative half-cycle. Fig.10 Figure ② in the middle is a waveform diagram after taking the absolute value of the current waveform in Figure ①. Fig.10 Figure ③ in the middle is a schematic diagram of the absolute value of the possible phase current waveform 1 when the permanent magnet synchronous motor has a phase loss, in which the current in the positive half cycle is much larger than the current in the negative half cycle. At this time, it can be determined that the motor has a phase loss. Fig.10 Figure ④ in the middle is a schematic diagram of the absolute value of the possible phase current waveform 2 when the permanent magnet synchronous motor is out of phase, in which the current in the negative half cycle is much larger than the current in the positive half cycle. At this time, it can also be judged that the motor is out of phase. In the scheme of the present invention, the motor's phase loss protection mechanism only needs to detect the motor phase current, and the judgment process is independent of the current motor's rotor angle, which can avoid problems such as protection failure and misprotection caused by the difference between the calculated rotor angle and the actual angle.

[0053] The scheme of the present invention provides a permanent magnet synchronous motor phase loss protection scheme that does not rely on the rotor angle of the motor. It does not need to read the rotor angle of the motor, but samples the phase current of the motor. The mechanism of judging whether the phase loss situation occurs only based on the phase current of the motor can be applied to the phase loss protection of the motor when it is unloaded and loaded, and effectively improves the reliability of the phase loss protection of the motor. Among them, since it is not necessary to read the rotor angle of the motor, the phase loss protection will not be invalid when there is a difference between the calculated rotor angle and the actual angle, which solves the problem that the permanent magnet synchronous motor controller in the related scheme needs to read the rotor angle of the motor to realize the phase loss protection function, and the phase loss protection will be invalid when there is a difference between the calculated rotor angle and the actual angle. Due to the sampling method for the phase current of the motor, it is compatible with three-phase, two-phase and single-phase current sampling methods at the same time, which solves the problem of the failure of phase loss protection during operation and the false triggering of protection during motor operation caused by the interference of current sampling in the phase loss protection mechanism of the permanent magnet synchronous motor controller in the related scheme.

[0054] In some embodiments, the specific process of determining whether one phase of the three-phase current of the motor is missing is performed in step S120 based only on the three-phase current of the motor in combination with a preset fault retrieval subroutine, as shown in the following exemplary description.

[0055] Combine the following Figure 2 The method of the present invention is shown as a flow chart of an embodiment of determining whether one phase of the three-phase current of the motor is lacking in phase only based on the three-phase current of the motor, further illustrating the specific process of determining whether one phase of the three-phase current of the motor is lacking in phase only based on the three-phase current of the motor in step S120, including: steps S210 to S230.

[0056] Step S210, determining whether the current current cycle is finished.

[0057] Step S220, if it is determined that the current current cycle has not ended, then within the current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated current of each phase in the full current cycle, the absolute value of the accumulated current of each phase in the positive half current cycle, and the absolute value of the accumulated current of each phase in the negative half current cycle are calculated, and then return to re-determine whether the current current cycle is ended; in this way, within the current current cycle, the absolute value of the accumulated current of the three-phase current of the full current cycle, the absolute value of the accumulated current of the three-phase current of the positive half current cycle, and the absolute value of the accumulated current of the three-phase current of the negative half current cycle are obtained.

[0058] Step S230, if it is determined that the current current cycle is over, a preset fault search subroutine is executed to determine whether one of the three-phase currents of the motor is out of phase by combining the absolute value of the accumulated value of the three-phase current of the full current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle. Furthermore, when it is determined that the one of the three-phase currents of the motor is out of phase, a reminder message of the one of the three-phase currents of the motor is out of phase is initiated, and the motor is controlled to stop to achieve phase loss protection for the motor.

[0059] The solution of the present invention does not need to read the rotor angle of the motor, but samples the phase current of the motor, and is compatible with three-phase, two-phase and single-phase current sampling methods; wherein, it is compatible with three-phase, two-phase and single-phase current sampling methods, that is, the phase loss protection detection scheme used in the solution of the present invention only needs to obtain the current sampling value within one cycle of any phase to make a phase loss fault judgment, and does not need to compare the current sampling values ​​between two or three phases. The mechanism of judging whether a phase loss occurs by comparing the accumulated value of the absolute value of the positive and negative half-cycle phase currents within a current cycle can be applied to the phase loss protection of the motor when it is unloaded and loaded, effectively improving the reliability of the phase loss protection of the motor.

[0060] In some embodiments, the current cycle includes: a positive half-current cycle and a negative half-current cycle; wherein the positive half-current cycle and the negative half-current cycle constitute a full current cycle.

[0061] In step S220, within the current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated current of each phase in the full current cycle, the absolute value of the accumulated current of each phase in the positive half current cycle, and the absolute value of the accumulated current of each phase in the negative half current cycle are calculated. Please refer to the following exemplary description for the specific process.

[0062] Combine the following Figure 3 The method of the present invention shown in the flowchart of an embodiment of calculating the absolute value of the accumulated current of each phase in the full current cycle, the absolute value of the accumulated current of each phase in the positive half current cycle, and the absolute value of the accumulated current of each phase in the negative half current cycle, further illustrates the specific process of calculating the absolute value of the accumulated current of each phase in the full current cycle, the absolute value of the accumulated current of each phase in the positive half current cycle, and the absolute value of the accumulated current of each phase in the negative half current cycle in step S220, including: steps S310 to S340.

[0063] Step S310, in the current cycle, for each phase current of the three-phase current of the motor, after taking the absolute value of each phase current obtained at the current moment, the accumulated value of each phase current in the entire current cycle is accumulated and taken as the absolute value, such as the accumulated value of the U-phase current is taken as the absolute value Ia_sumAbs.

[0064] Step S320, determining whether the current moment belongs to a positive half current cycle within the current current cycle.

[0065] Step S330, if it is determined that the current moment belongs to the positive half current cycle within the current current cycle, then after taking the absolute value of each phase current obtained at the current moment, the accumulated value of each phase current in the positive half current cycle is accumulated and taken as the absolute value, such as the accumulated value of the U-phase current in the positive half current cycle is taken as the absolute value Ia_PosAbs, and then return to re-determine whether the current current cycle is over.

[0066] Step S340, if it is determined that the current moment does not belong to the positive half-current cycle of the current cycle, then after taking the absolute value of each phase current obtained at the current moment, the accumulated value of each phase current in the negative half-current cycle is added and taken as the absolute value, such as the accumulated value of the U-phase current in the negative half-current cycle is taken as the absolute value Ia_NegAbs, and then return to re-determine whether the current current cycle is over.

[0067] That is to say, in the current current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated value of each phase current of the full current cycle, the absolute value of the accumulated value of each phase current of the positive half current cycle, and the absolute value of the accumulated value of each phase current of the negative half current cycle are calculated. When the current current cycle ends, for each phase current of the three-phase current of the motor, according to the absolute value of the accumulated value of each phase current of the full current cycle, the absolute value of the accumulated value of each phase current of the positive half current cycle, and the absolute value of the accumulated value of each phase current of the negative half current cycle, a preset fault search subroutine is executed to determine whether one phase current of the three-phase current of the motor is out of phase; further, when it is determined that the one phase current of the three-phase current of the motor is out of phase, a reminder message of the one phase current of the three-phase current of the motor is out of phase is initiated, and the motor is controlled to stop, so as to achieve phase-out protection for the motor.

[0068] Fig.11 FIG. 1 is a flow chart of the main program of the phase loss protection in the phase loss protection detection method of the present invention. Fig.11 As shown, in the phase loss protection mechanism of the motor provided by the solution of the present invention, the process of the phase loss protection main program includes:

[0069] Step 11, first, the motor controller will initialize AD sampling (i.e., the process of converting the sampled analog signal into a digital signal), collect the three-phase current value of the motor in real time through the current sampling circuit [4] and input it into the phase loss protection detection module [5], and then execute step 12. The three-phase current value of the motor collected in real time by the current sampling circuit [4] includes: U phase current Ia, V phase current Ib and W phase current Ic.

[0070] Step 12: The phase loss protection detection module [5] determines whether the current cycle has ended. If so, the fault search subroutine is executed. Fig.12 Otherwise, proceed to step 13.

[0071] Step 13, based on the three-phase current values ​​of the motor collected in real time by the current sampling circuit [4], the phase loss protection detection module [5] takes the absolute value of each phase current and adds it to the accumulated value of each phase current: the absolute value of the U-phase current Ia is added to the accumulated value of the U-phase current Ia_sumAbs, and the same processing is performed on the V-phase current Ib and the W-phase current Ic, and then step 14 is executed.

[0072] Step 14, determine whether the current cycle is a positive half cycle: if so, execute step 15, otherwise execute step 16.

[0073] Step 15, take the absolute value of each phase current and add it to the positive half-cycle current accumulated value: take the absolute value of the U-phase current Ia and add it to the U-phase current accumulated value of the positive half-current cycle to take the absolute value Ia_PosAbs, and perform the same processing on the V-phase current Ib and the W-phase current Ic, and then return to step 12.

[0074] Step 16, take the absolute value of each phase current and add it to the negative half-cycle current accumulated value: take the absolute value of the U-phase current Ia and add it to the U-phase current accumulated value of the negative half-current cycle to take the absolute value Ia_NegAbs, and perform the same processing on the V-phase current Ib and the W-phase current Ic, and then return to step 12.

[0075] against Fig.11 In the example shown, in steps 12 to 16, taking the U phase as an example, after receiving the U phase current Ia collected by the current sampling circuit [4], the phase loss protection detection module [5] calculates the absolute value Ia_sumAbs of the accumulated value of the U phase current, the absolute value Ia_PosAbs of the accumulated value of the U phase current in the positive half current cycle, and the absolute value Ia_NegAbs of the accumulated value of the U phase current in the negative half current cycle. After the current current cycle ends, the phase loss fault search subroutine is entered. Among them, the current cycle refers to the time required for the alternating current to complete a periodic change; within one current cycle, the direction of the alternating current changes twice.

[0076] In the scheme of the present invention, see Fig.11 In the example shown, by taking the phase current data of a current cycle for calculation, it is ensured that the data taken includes all phase current data of the motor's 0° to 360° electrical angle, making the data used for calculation more representative; accumulating the phase current data and then participating in the calculation and judgment can smooth out some instantaneous interference signals and make the calculation results more accurate. At the same time, due to the fact that the instantaneous value of the current may have a large range of variation under different working environments and load conditions, it is difficult to set a fixed protection threshold; and the current accumulation value can better adapt to different application scenarios by adjusting the integration time and protection threshold.

[0077] In some embodiments, for one-phase current of the three-phase current of the motor, the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle are taken, including: the absolute value of the accumulated value of one-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of one-phase current of the positive half current cycle, and the absolute value of the accumulated value of one-phase current of the negative half current cycle.

[0078] The preset fault retrieval subroutine is executed in step S230 to determine whether one phase of the three-phase current of the motor is missing by combining the absolute value of the accumulated value of the three-phase current of the full current cycle within the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle. The specific process is described in the following exemplary description.

[0079] Combine the following Figure 4 The method of the present invention shown is a flow chart of an embodiment of determining whether one phase of the three-phase current of the motor is missing by taking the absolute value of the accumulated three-phase current of the full current cycle, the absolute value of the accumulated three-phase current of the positive half current cycle, and the absolute value of the accumulated three-phase current of the negative half current cycle, further illustrating the specific process of determining whether one phase of the three-phase current of the motor is missing by taking the absolute value of the accumulated three-phase current of the full current cycle, the absolute value of the accumulated three-phase current of the positive half current cycle, and the absolute value of the accumulated three-phase current of the negative half current cycle in step S230, including: steps S410 to S420.

[0080] Step S410, execute a preset fault retrieval subroutine to determine whether one of the three-phase currents of the motor in the current cycle satisfies at least one of the following conditions: the absolute value of the accumulated value of the current of the phase in the positive half-current cycle is smaller than the ratio of the absolute value of the accumulated value of the current of the phase in the negative half-current cycle to the set coefficient, the absolute value of the accumulated value of the current of the phase in the negative half-current cycle is smaller than the ratio of the absolute value of the accumulated value of the current of the phase in the positive half-current cycle to the set coefficient, and the absolute value of the accumulated value of the current of the phase in the full current cycle is smaller than the ratio of the sum of the absolute values ​​of the accumulated values ​​of the other two phases in the full current cycle to the set coefficient; wherein the set coefficient is greater than 1, for example, the set coefficient is 4.

[0081] Step S420, adjusting the preset cumulative fault count value according to the determination result; and determining whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value.

[0082] In the solution of the present invention, when the permanent magnet synchronous motor is in the non-starting state, refer to Figure 8In the example shown, the motor controller initializes each module. After the initialization of each module is completed, the permanent magnet synchronous motor enters the running state, and the motor controller enters the fault detection state. At this time, the motor controller will detect various types of faults in real time through various fault detection modules. Among them, the motor controller detects the possible phase loss of the permanent magnet synchronous motor through the phase loss protection detection module. The basic principle of detection is to determine whether a phase loss occurs by analyzing the three-phase current value. When the positive half-cycle current in a current cycle is much larger than the negative half-cycle current (or the negative half-cycle current is much larger than the positive half-cycle current) or the current of one phase is much smaller than the sum of the other two phase currents, it is determined that a phase loss occurs. It can be applied to both no-load and loaded phase loss protection of the motor. For details, please refer to Fig.10 Example shown.

[0083] The motor controller detects the possible phase loss of the permanent magnet synchronous motor through the phase loss protection detection module. The basic process of the detection is to collect the three-phase current values ​​in real time through the current sampling circuit [4], calculate the absolute value of the accumulated value of each phase current in one cycle, the absolute value of the accumulated value of each phase current in the positive half cycle, and the absolute value of the accumulated value of each phase current in the negative half cycle; then Fig.10 The three judgment conditions in the detection principle shown in the figure determine whether to accumulate the fault accumulation value; when the fault accumulation value accumulates to the set number of 10 times, the phase loss protection is triggered, and the phase loss protection detection module [5] sends a fault signal to the main control chip [2]. For details, please refer to Fig.11 and Fig.12 The example shown. After the main control chip [2] receives the fault signal, the main control chip [2] will turn off the output of the PWM signal to stop the motor until the fault is eliminated. In this way, the mechanism of judging whether a phase loss occurs by comparing the accumulated value of the absolute value of the positive and negative half-cycle phase currents in a current cycle effectively improves the reliability of the phase loss protection of the motor.

[0084] In some embodiments, the determination result is: determining that it is not satisfied, or determining that it is satisfied. In step S420, according to the determination result, the preset cumulative fault count value is adjusted; and according to the adjusted preset cumulative fault count value, the specific process of determining whether the one phase current of the three-phase current of the motor is missing is shown in the following exemplary description.

[0085] Combine the following Figure 5 The method of the present invention is shown as a flow chart of an embodiment of determining whether one phase of the three-phase current of the motor is missing according to the determination result, further illustrating the specific process of determining whether one phase of the three-phase current of the motor is missing according to the determination result in step S420, including: steps S510 to S530.

[0086] Step S510, determining whether the determination result is determined to be not satisfied or determined to be satisfied.

[0087] Step S520, if the determination result is that the condition is not satisfied, then when the preset cumulative fault count value is equal to 0, directly return to re-execute the preset fault search subroutine; when the preset cumulative fault count value is greater than 0, reduce the preset cumulative fault count value by 1, and then return to re-execute the preset fault search subroutine. The initial value of the preset cumulative fault count value is 0.

[0088] Step S530: If the determination result is satisfied, the preset cumulative fault count value is increased by 1; thereafter, based on the adjusted preset cumulative fault count value, it is determined whether one phase of the three-phase current of the motor is missing.

[0089] Fig.12 FIG. 1 is a flow chart of a U-phase failure fault retrieval subroutine in the phase failure protection detection method of the present invention. Fig.12 As shown in FIG. 1 , the process of the phase failure retrieval subroutine taking the U phase as an example includes:

[0090] Step 21, after entering the phase failure fault search subroutine, there are three judgment conditions, and it is determined whether at least one of the three judgment conditions is met: if so, step 22 is executed; otherwise, if the accumulated fault count value FaultACnt is greater than 0, the accumulated fault count value FaultACnt is reduced by 1, and then returns to step 21. Among them, if the accumulated fault count value FaultACnt is less than or equal to 0, it directly returns to step 21.

[0091] In step 21, the three determination conditions are: a first determination condition, a second determination condition and a third determination condition.

[0092] Among them, the first judgment condition is: the U phase positive half cycle current is much smaller than the U phase negative half cycle current (Ia_PosAbs <Ia_NegAbs / 4)。

[0093] The second judgment condition is: the negative half-cycle current of phase U is much smaller than the positive half-cycle current of phase U (Ia_NegAbs <Ia_PosAbs / 4)。

[0094] The third judgment condition is: the accumulated value of the U-phase current is much smaller than the accumulated value of the other two-phase currents (Ia_sumAbs<(Ib_sumAbs+Ic_sumAbs) / 4).

[0095] Step 22: add 1 to the accumulated fault count value FaultACnt, and then execute step 23 to implement phase loss detection for the U phase according to the accumulated fault count value FaultACnt.

[0096] In the solution of the present invention, the accumulated fault count value FaultACnt is calculated simultaneously through three judgment conditions, so that the triggering range is wider, and the ability of the program to identify phase loss faults can be improved.

[0097] In some implementations, the specific process of determining whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value in step S530 is described in the following exemplary embodiments.

[0098] Combine the following Figure 6 The method of the present invention is shown as a flow chart of an embodiment of determining whether one phase of the three-phase current of the motor is lacking in phase according to the adjusted preset cumulative fault count value, further illustrating the specific process of determining whether one phase of the three-phase current of the motor is lacking in phase according to the adjusted preset cumulative fault count value in step S530, including: steps S610 to S630.

[0099] Step S610, determining whether the adjusted preset cumulative fault count value is greater than a set number of times, wherein the set number of times is, for example, 10 times.

[0100] Step S620: If it is determined that the adjusted preset cumulative fault count value is not greater than the set number of times, the process returns to re-execute the preset fault search subroutine.

[0101] Step S630, if it is determined that the adjusted preset cumulative fault count value is greater than the set number of times, it is determined that the one phase of the three-phase current of the motor is out of phase; then, a reminder message about the one phase of the three-phase current of the motor being out of phase is initiated, and the motor is controlled to shut down to achieve phase-out protection for the motor.

[0102] like Fig.12 As shown, the process of the phase failure fault retrieval subroutine taking the U phase as an example also includes: step 23, if the accumulated fault count value FaultACnt is greater than 10, the accumulated fault count value FaultACnt is cleared, and a U phase failure fault signal is issued to realize the phase failure detection of the U phase. If the accumulated fault count value FaultACnt is less than or equal to 10, the fault retrieval step is returned, that is, the process returns to step 21.

[0103] In the solution of the present invention, the accumulated fault count value FaultACnt is increased and decreased through three judgment conditions. When the accumulated fault count value FaultACnt reaches a certain number, such as 10, the phase loss fault protection is triggered to send a fault signal to the main control chip [2]. In this way, the accumulated fault count value FaultACnt is calculated simultaneously through three judgment conditions, and the trigger range is wider, which can improve the ability of the program to identify phase loss faults; by triggering the phase loss protection when the accumulated fault count value FaultACnt reaches a certain number, such as 10, it can prevent the protection from being falsely triggered due to motor phase current fluctuations in extreme situations.

[0104] See also Figures 8 to 12 The example shown in the figure shows the specific control logic of the permanent magnet synchronous motor phase loss protection system, including:

[0105] Step 31, after the motor controller is initialized, the bias voltage and other parameters are collected and ensured that these parameters are within the normal error range, wherein the bias voltage should be within the range of 1.65V plus or minus 10% to ensure the accuracy of current sampling. Among them, the bias voltage and other parameters include: bias voltage, IPM module temperature, main control chip and IPM module power supply voltage, SVPWM control parameters, PI parameters of current loop and voltage loop. The bias voltage here is the bias voltage of the op amp input in the current sampling circuit. When the motor is not started, the bias voltage is collected and calculated through AD sampling. The normal bias voltage should be within the range of 1.6V±10%. If it exceeds this range, it enters the bias protection state. Then initialize the phase loss fault protection module [5] and clear the phase loss fault flag.

[0106] Step 32: After the initialization work is completed, the permanent magnet synchronous motor enters the running state, and the motor controller detects the possible phase loss of the permanent magnet synchronous motor through the phase loss protection detection module [5].

[0107] Taking the U phase as an example, the open-phase protection detection module [5] initializes the AD sampling and samples the current of the U phase of the motor in the AD interrupt. After the sampling is completed, it is judged whether the current current cycle has ended. If the current current cycle has not ended, the absolute value of the U-phase current value Ia sampled this time is accumulated to the absolute value of the accumulated value of the U-phase current Ia_sumAbs. After calculating Ia_sumAbs, it is judged whether the current is the positive half cycle. If the current is the positive half current cycle, the absolute value of Ia is accumulated to the absolute value of the accumulated value of the U-phase current Ia_PosAbs in the positive half current cycle; otherwise, the absolute value of Ia is accumulated to the absolute value of the accumulated value of the U-phase current Ia_NegAbs in the negative half current cycle. Then, it is judged again whether the current current cycle has ended. If it has not ended, the accumulation calculation continues. If it has ended, the fault retrieval subroutine is entered. In the fault retrieval subroutine, the judgment conditions are as follows: 1) The current in the positive half cycle of the U phase is much smaller than the current in the negative half cycle of the U phase (Ia_PosAbs < Ia_NegAbs / 4); 2) The current in the negative half cycle of the U phase is much smaller than the current in the positive half cycle of the U phase (Ia_NegAbs < Ia_PosAbs / 4); 3) The accumulated value of the U-phase current value is much smaller than the accumulated values of the currents of the other two phases (Ia_sumAbs < (Ib_sumAbs + Ic_sumAbs) / 4); After starting the fault retrieval, if the judgment conditions are met, the U-phase fault count value is incremented by 1, otherwise the fault count value is decremented by 1. When the cumulative fault count value FaultACnt is greater than 10, the fault count value is cleared, and at the same time, a U-phase open-phase fault signal is sent to the main control chip [2] to stop the motor.

[0108] In the solution of the present invention, the rotor angle does not need to be read; the open-phase judgment conditions are: the ratio of the absolute value of the accumulated current in the upper half cycle to the absolute value of the accumulated current in the lower half cycle of the single-phase current, and the ratio of the absolute value of the accumulated current of one phase to the absolute values of the currents of the other two phases; the current sampling method is: compatible with three-phase, two-phase and single-phase current sampling; and it is applicable to both load and no-load conditions at the same time. Taking the phase current data of one current cycle for calculation ensures that the data used includes all the phase current data of the motor from 0 to 360° electrical angle, making the data used for calculation more representative. After accumulating the obtained phase current data and then participating in the calculation and judgment, some instantaneous interference signals can be smoothed out, making the calculation result more accurate. At the same time, in different working environments and load conditions, the instantaneous value of the current may have a large range of changes, which makes it difficult to set a fixed protection threshold. The accumulated current value can better adapt to different application scenarios by adjusting the integration time and the protection threshold. By calculating the cumulative fault value simultaneously through three judgment conditions, the triggering range is wider, and the ability of the program to identify open-phase faults can be improved. Triggering open-phase protection by accumulating the fault value to a certain number can prevent mis-triggering of protection caused by the fluctuation of the motor phase current in extreme cases.

[0109] The technical solution of this embodiment is adopted, by obtaining the three-phase current of the motor according to the set current cycle when executing the phase loss protection mechanism of the motor (such as a permanent magnet synchronous motor); when a current current cycle has not ended, for each phase current of the three-phase current of the motor, the absolute value of the accumulated value of each phase current of the full current cycle of the motor, the absolute value of the accumulated value of each phase current of the positive half current cycle, and the absolute value of the accumulated value of each phase current of the negative half current cycle are calculated within one current cycle; when a current current cycle ends, a preset fault retrieval subroutine is entered, and for each phase current of the three-phase current of the motor, the accumulated fault count value of each phase current is increased and decreased according to three judgment conditions, and the phase loss protection is triggered when the accumulated fault count value of each phase current reaches a certain number; thereby, the reliability of the phase loss protection of the motor is improved by performing phase loss protection based only on the three-phase current of the motor without relying on the rotor angle of the motor.

[0110] According to an embodiment of the present invention, a motor protection device corresponding to the motor protection method is also provided. Figure 7 The structure diagram of an embodiment of the device of the present invention is shown in FIG. The motor has three-phase windings, such as a U-phase winding, a V-phase winding and a W-phase winding; in the solution of the present invention, Figure 7 As shown, the motor protection device includes: an acquisition unit 102 and a control unit 104 .

[0111] Wherein, the acquisition unit 102 is configured to acquire the phase current of each phase winding of the motor for each phase winding of the three-phase winding of the motor during the operation of the motor when the phase loss protection mechanism of the motor is enabled, that is, to acquire the phase current of each phase winding of the three-phase winding of the motor; thereby, the three-phase current of the motor is obtained. Wherein, when acquiring the phase current of each phase winding of the three-phase winding of the motor, it can be acquired at a set sampling period or in real time. The specific functions and processing of the acquisition unit 102 refer to step S110.

[0112] The control unit 104 is configured to determine whether one of the three-phase currents of the motor is missing based only on the three-phase current of the motor and in combination with a preset fault search subroutine. The specific functions and processing of the control unit 104 refer to step S120. And,

[0113] The control unit 104 is further configured to, when determining that the one phase of the three-phase current of the motor is out of phase, initiate a reminder message of the one phase of the three-phase current of the motor being out of phase, and control the motor to stop, so as to implement phase-out protection for the motor. The specific functions and processing of the control unit 104 are also referred to step S130.

[0114] Figure 8 FIG. 1 is a schematic diagram of the structure of an embodiment of a permanent magnet synchronous motor phase loss protection system. Figure 8 As shown, the permanent magnet synchronous motor phase loss protection system includes: a permanent magnet synchronous motor [1], a main control chip [2], a power device IPM module [3], a current sampling circuit [4] and a phase loss protection detection module [5]. The power device IPM module [3] is connected between the pulse width modulation (PWM) signal output end of the main control chip [2] and the three-phase phase line of the permanent magnet synchronous motor [1]. The current sampling circuit [4] and the phase loss protection detection module [5] are connected in sequence between the three-phase winding of the permanent magnet synchronous motor [1] and the input end of the main control chip [2]. Among them, the power device IPM module [3] is an intelligent power module (Intelligent Power Module, IPM).

[0115] The main control chip [2] is used to receive the fault signal from the phase loss protection detection module [5], and control the operation and shutdown of the power device IPM module [3] by opening and closing the output of the six-way PWM signal; the power device IPM module [3] is used to receive the six-way PWM signal output from the main control chip [2], and generate a sinusoidal current to drive the permanent magnet synchronous motor [1] to operate by opening and closing the upper and lower bridge IGBTs; the current sampling circuit [4] is used to collect the current flowing through the three-phase winding of the permanent magnet synchronous motor [1], and input the collected current value to the phase loss protection detection module [5]; the phase loss protection detection module [5] is used to analyze the three-phase current value collected by the current sampling circuit [4], and when any phase of the three phases of the motor is missing, trigger the motor controller to perform phase loss protection, and output a fault signal to the main control chip [2].

[0116] See also Figure 8 In the example shown, the present invention provides a permanent magnet synchronous motor phase loss protection scheme that does not require reading the rotor angle of the motor. The main control chip [2] outputs a three-phase complementary PWM signal to the power device IPM module [3]. The power device IPM module [3] drives the motor to run. When the motor is running, the current on the three-phase line is collected by the sampling circuit to the phase loss protection detection module. When the program determines that any phase is missing, the detection module outputs a fault signal to the main control chip [2].

[0117] Fig. 9 Figure 1 is a schematic diagram of the curve of the electrical angle (Theta) and the phase current I in the phase loss protection detection method in the relevant scheme, wherein Figure 1 is a schematic diagram of the phase current waveform of any phase when the permanent magnet synchronous motor is operating normally, and Figure 2 is a schematic diagram of the possible phase current waveform when the permanent magnet synchronous motor has a phase loss. Fig. 9 As shown, half a current cycle is taken as an analysis cycle. Fig. 9 Figure ① is a schematic diagram of the phase current waveform of any phase when the permanent magnet synchronous motor is operating normally. In the entire analysis cycle, it is necessary to first select a current threshold value, which is used to compare with the actual sampled current value, and divide the current waveform of the entire half cycle into two parts, the upper and lower parts. The electrical angle range of the current waveform greater than the threshold is as follows: Fig. 9 As shown in Figure ①, it is: θ2-θ1. When the motor is running normally and there is no phase loss, the θ2-θ1 part will occupy more than 2 / 3 of the entire current half cycle, that is, θ2-θ1>120°.

[0118] Fig. 9 Figure ② is a schematic diagram of the possible phase current waveform when the permanent magnet synchronous motor is missing a phase. The entire waveform is also divided into two parts, the part greater than the current threshold, such as Fig. 9 As shown in Figure ②, it is: θ2-θ1, θ4-θ3, θ6-θ5; θ1, θ2, θ3, θ4, θ5, θ6 are all the rotor angles of the motor, that is, the electrical angles. At this time, the sum of the angle ranges corresponding to all parts greater than the current threshold will be less than 120°, indicating that the effective value of one phase current is less than the normal range at this time. At this time, it is judged that the motor is missing a phase. The phase loss protection mechanism in the relevant scheme needs to detect the motor phase current and the rotor angle of the motor at the same time, and the implementation depends on the rotor angle of the motor. When there is a difference between the calculated rotor angle and the actual angle, there is also an error between the electrical angle recorded by the program and the actual electrical angle at that moment, resulting in the judgment of the electrical angle range not being consistent with the actual situation, and a misjudgment causing the phase loss protection to fail or the protection to be mistriggered.

[0119] Compared with the solution of the present invention, the related solutions all need to detect the motor phase current, and the phase current value read is used for calculation to determine whether the motor has a phase loss. However, the related solutions need to detect the motor phase current and the motor rotor angle at the same time, and determine whether a phase loss occurs by calculating the electrical angle range that exceeds the current threshold. The judgment result is affected by the rotor angle calculated by the program. The solution of the present invention only needs to detect the motor phase current, and can determine whether the motor has a phase loss by calculation, and the protection reliability is higher.

[0120] Fig.10 The diagram is a curve diagram of the electrical angle (Theta) and the phase current I in the phase loss protection detection method of the present invention, wherein Figure 1 is a waveform diagram of the phase current of any phase when the permanent magnet synchronous motor is operating normally, Figure 2 is a waveform diagram after taking the absolute value of the current waveform of Figure 1, Figure 3 is a diagram of the absolute value of the possible phase current waveform 1 when the permanent magnet synchronous motor has a phase loss, and Figure 4 is a diagram of the absolute value of the possible phase current waveform 2 when the permanent magnet synchronous motor has a phase loss. Fig.10 As shown, the entire current cycle is taken as one analysis cycle. Fig.10Figure ① in the middle is a schematic diagram of the phase current waveform of any phase during normal operation of the permanent magnet synchronous motor. The entire waveform is divided into a positive half-cycle and a negative half-cycle. Fig.10 Figure ② in the middle is a waveform diagram after taking the absolute value of the current waveform in Figure ①. Fig.10 Figure ③ in the middle is a schematic diagram of the absolute value of the possible phase current waveform 1 when the permanent magnet synchronous motor has a phase loss, in which the current in the positive half cycle is much larger than the current in the negative half cycle. At this time, it can be determined that the motor has a phase loss. Fig.10 Figure ④ in the middle is a schematic diagram of the absolute value of the possible phase current waveform 2 when the permanent magnet synchronous motor is out of phase, in which the current in the negative half cycle is much larger than the current in the positive half cycle. At this time, it can also be judged that the motor is out of phase. In the scheme of the present invention, the motor's phase loss protection mechanism only needs to detect the motor phase current, and the judgment process is independent of the current motor's rotor angle, which can avoid problems such as protection failure and misprotection caused by the difference between the calculated rotor angle and the actual angle.

[0121] The scheme of the present invention provides a permanent magnet synchronous motor phase loss protection scheme that does not rely on the rotor angle of the motor. It does not need to read the rotor angle of the motor, but samples the phase current of the motor. The mechanism of judging whether the phase loss situation occurs only based on the phase current of the motor can be applied to the phase loss protection of the motor when it is unloaded and loaded, and effectively improves the reliability of the phase loss protection of the motor. Among them, since it is not necessary to read the rotor angle of the motor, the phase loss protection will not be invalid when there is a difference between the calculated rotor angle and the actual angle, which solves the problem that the permanent magnet synchronous motor controller in the related scheme needs to read the rotor angle of the motor to realize the phase loss protection function, and the phase loss protection will be invalid when there is a difference between the calculated rotor angle and the actual angle. Due to the sampling method for the phase current of the motor, it is compatible with three-phase, two-phase and single-phase current sampling methods at the same time, which solves the problem of the failure of phase loss protection during operation and the false triggering of protection during motor operation caused by the interference of current sampling in the phase loss protection mechanism of the permanent magnet synchronous motor controller in the related scheme.

[0122] In some implementations, the control unit 104 determines whether one phase of the three-phase current of the motor is missing based only on the three-phase current of the motor in combination with a preset fault search subroutine, including:

[0123] The control unit 104 is further configured to determine whether the current current cycle is over. The specific functions and processing of the control unit 104 are also shown in step S210.

[0124] The control unit 104 is also specifically configured to calculate the absolute value of the accumulated current value of each phase of the three-phase current of the motor in the current cycle if it is determined that the current cycle has not ended, and then return to re-determine whether the current cycle has ended; in this way, the absolute value of the accumulated current value of the three-phase current of the full current cycle, the absolute value of the accumulated current value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated current value of the three-phase current of the negative half current cycle are obtained in the current cycle. The specific functions and processing of the control unit 104 are also shown in step S220.

[0125] The control unit 104 is also specifically configured to execute a preset fault search subroutine if it is determined that the current current cycle ends, so as to determine whether one phase of the three-phase current of the motor is missing by combining the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle. Furthermore, in the case of determining that the one phase of the three-phase current of the motor is missing, a reminder message of the one phase of the three-phase current of the motor is missing, and the motor is controlled to stop, so as to implement the phase-missing protection of the motor. The specific functions and processing of the control unit 104 are also shown in step S230.

[0126] The solution of the present invention does not need to read the rotor angle of the motor, but samples the phase current of the motor, and is compatible with three-phase, two-phase and single-phase current sampling methods at the same time; by comparing the accumulated values ​​of the absolute values ​​of the positive and negative half-cycle phase currents within a current cycle to determine whether a phase loss situation occurs, it can be applied to both no-load and loaded phase loss protection of the motor, effectively improving the reliability of the phase loss protection of the motor.

[0127] In some embodiments, the current current cycle includes: a positive half current cycle and a negative half current cycle; wherein the positive half current cycle and the negative half current cycle constitute a full current cycle. The control unit 104 calculates the absolute value of the accumulated current of each phase in the three-phase current of the motor in the current cycle, the absolute value of the accumulated current of each phase in the positive half current cycle, and the absolute value of the accumulated current of each phase in the negative half current cycle, including:

[0128] The control unit 104 is further configured to, in the current current cycle, take the absolute value of each phase current obtained at the current moment for each phase current of the three-phase current of the motor, and then add the absolute value of the accumulated value of each phase current in the full current cycle, such as the accumulated value of the U-phase current taking the absolute value Ia_sumAbs. The specific functions and processing of the control unit 104 are also referred to step S310.

[0129] The control unit 104 is further configured to determine whether the current moment belongs to a positive half current cycle in the current current cycle. The specific functions and processing of the control unit 104 are also shown in step S320.

[0130] The control unit 104 is further configured to, if it is determined that the current moment belongs to the positive half current cycle within the current cycle, take the absolute value of each phase current acquired at the current moment, and then add the absolute value of the accumulated value of each phase current in the positive half current cycle, such as the absolute value Ia_PosAbs of the accumulated value of the U phase current in the positive half current cycle, and then return to re-determine whether the current current cycle is over. The specific functions and processing of the control unit 104 are also shown in step S330.

[0131] The control unit 104 is further configured to take the absolute value of each phase current acquired at the current moment, and then take the absolute value of the accumulated value of each phase current in the negative half current cycle after determining that the current moment does not belong to the positive half current cycle of the current cycle, such as taking the absolute value Ia_NegAbs of the accumulated value of the U phase current in the negative half current cycle, and then return to re-determine whether the current current cycle is over. The specific functions and processing of the control unit 104 are also shown in step S340.

[0132] That is to say, the control unit 104 is also configured to calculate the absolute value of the accumulated value of each phase current in the full current cycle, the absolute value of the accumulated value of each phase current in the positive half current cycle, and the absolute value of the accumulated value of each phase current in the negative half current cycle for each phase current of the three-phase current of the motor in the current cycle. When the current current cycle ends, for each phase current in the three-phase current of the motor, according to the absolute value of the accumulated value of each phase current in the full current cycle, the absolute value of the accumulated value of each phase current in the positive half current cycle, and the absolute value of the accumulated value of each phase current in the negative half current cycle, a preset fault search subroutine is executed to determine whether one phase current in the three-phase current of the motor is out of phase; further, when it is determined that the one phase current in the three-phase current of the motor is out of phase, a reminder message of the one phase current in the three-phase current of the motor is out of phase is initiated, and the motor is controlled to stop, so as to achieve phase-out protection for the motor.

[0133] Fig.11FIG. 1 is a flow chart of the main program of the phase loss protection in the phase loss protection detection method of the present invention. Fig.11 As shown, in the phase loss protection mechanism of the motor provided by the solution of the present invention, the process of the phase loss protection main program includes:

[0134] Step 11, first, the motor controller will initialize AD sampling (i.e., the process of converting the sampled analog signal into a digital signal), collect the three-phase current value of the motor in real time through the current sampling circuit [4] and input it into the phase loss protection detection module [5], and then execute step 12. The three-phase current value of the motor collected in real time by the current sampling circuit [4] includes: U phase current Ia, V phase current Ib and W phase current Ic.

[0135] Step 12: The phase loss protection detection module [5] determines whether the current cycle has ended. If so, the fault search subroutine is executed. Fig.12 Otherwise, proceed to step 13.

[0136] Step 13, based on the three-phase current values ​​of the motor collected in real time by the current sampling circuit [4], the phase loss protection detection module [5] takes the absolute value of each phase current and adds it to the accumulated value of each phase current: the absolute value of the U-phase current Ia is added to the accumulated value of the U-phase current Ia_sumAbs, and the same processing is performed on the V-phase current Ib and the W-phase current Ic, and then step 14 is executed.

[0137] Step 14, determine whether the current cycle is a positive half cycle: if so, execute step 15, otherwise execute step 16.

[0138] Step 15, take the absolute value of each phase current and add it to the positive half-cycle current accumulated value: take the absolute value of the U-phase current Ia and add it to the U-phase current accumulated value of the positive half-current cycle to take the absolute value Ia_PosAbs, and perform the same processing on the V-phase current Ib and the W-phase current Ic, and then return to step 12.

[0139] Step 16, take the absolute value of each phase current and add it to the negative half-cycle current accumulated value: take the absolute value of the U-phase current Ia and add it to the U-phase current accumulated value of the negative half-current cycle to take the absolute value Ia_NegAbs, and perform the same processing on the V-phase current Ib and the W-phase current Ic, and then return to step 12.

[0140] against Fig.11In the example shown, in steps 12 to 16, taking the U phase as an example, after receiving the U phase current Ia collected by the current sampling circuit [4], the phase loss protection detection module [5] calculates the absolute value Ia_sumAbs of the accumulated value of the U phase current, the absolute value Ia_PosAbs of the accumulated value of the U phase current in the positive half current cycle, and the absolute value Ia_NegAbs of the accumulated value of the U phase current in the negative half current cycle. After the current current cycle ends, the phase loss fault search subroutine is entered. Among them, the current cycle refers to the time required for the alternating current to complete a periodic change; within one current cycle, the direction of the alternating current changes twice.

[0141] In the scheme of the present invention, see Fig.11 In the example shown, by taking the phase current data of a current cycle for calculation, it is ensured that the data taken includes all phase current data of the motor's 0° to 360° electrical angle, making the data used for calculation more representative; accumulating the phase current data and then participating in the calculation and judgment can smooth out some instantaneous interference signals and make the calculation results more accurate. At the same time, due to the fact that the instantaneous value of the current may have a large range of variation under different working environments and load conditions, it is difficult to set a fixed protection threshold; and the current accumulation value can better adapt to different application scenarios by adjusting the integration time and protection threshold.

[0142] In some embodiments, for one-phase current of the three-phase current of the motor, the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle are taken, including: the absolute value of the accumulated value of one-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of one-phase current of the positive half current cycle, and the absolute value of the accumulated value of one-phase current of the negative half current cycle.

[0143] The control unit 104 executes a preset fault search subroutine to determine whether one phase of the three-phase current of the motor is missing by combining the absolute value of the accumulated value of the three-phase current of the full current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle in the current cycle, including:

[0144] The control unit 104 is also specifically configured to execute a preset fault search subroutine to determine whether at least one of the following is satisfied for one phase current of the three-phase current of the motor in the current cycle: the absolute value of the accumulated value of the current of the phase in the positive half current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the negative half current cycle to the set coefficient, the absolute value of the accumulated value of the current of the phase in the negative half current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the positive half current cycle to the set coefficient, and the absolute value of the accumulated value of the current of the phase in the full current cycle is less than the ratio of the sum of the absolute values ​​of the accumulated values ​​of the other two phase currents in the full current cycle to the set coefficient; wherein the set coefficient is greater than 1, for example, the set coefficient is 4. The specific functions and processing of the control unit 104 are also referred to step S410.

[0145] The control unit 104 is further configured to adjust the preset cumulative fault count value according to the determination result; and determine whether the one phase current of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value. The specific functions and processing of the control unit 104 are also shown in step S420.

[0146] In the solution of the present invention, when the permanent magnet synchronous motor is in the non-starting state, refer to Figure 8 In the example shown, the motor controller initializes each module. After the initialization of each module is completed, the permanent magnet synchronous motor enters the running state, and the motor controller enters the fault detection state. At this time, the motor controller will detect various types of faults in real time through various fault detection modules. Among them, the motor controller detects the possible phase loss of the permanent magnet synchronous motor through the phase loss protection detection module. The basic principle of detection is to determine whether a phase loss occurs by analyzing the three-phase current value. When the positive half-cycle current in a current cycle is much larger than the negative half-cycle current (or the negative half-cycle current is much larger than the positive half-cycle current) or the current of one phase is much smaller than the sum of the other two phase currents, it is determined that a phase loss occurs. It can be applied to both no-load and loaded phase loss protection of the motor. For details, please refer to Fig.10 Example shown.

[0147] The motor controller detects the possible phase loss of the permanent magnet synchronous motor through the phase loss protection detection module. The basic process of the detection is to collect the three-phase current values ​​in real time through the current sampling circuit [4], calculate the absolute value of the accumulated value of each phase current in one cycle, the absolute value of the accumulated value of each phase current in the positive half cycle, and the absolute value of the accumulated value of each phase current in the negative half cycle; then Fig.10 The three judgment conditions in the detection principle shown in the figure determine whether to accumulate the fault accumulation value; when the fault accumulation value accumulates to the set number of 10 times, the phase loss protection is triggered, and the phase loss protection detection module [5] sends a fault signal to the main control chip [2]. For details, please refer to Fig.11 and Fig.12The example shown. After the main control chip [2] receives the fault signal, the main control chip [2] will turn off the output of the PWM signal to stop the motor until the fault is eliminated. In this way, the mechanism of judging whether a phase loss occurs by comparing the accumulated value of the absolute value of the positive and negative half-cycle phase currents in a current cycle effectively improves the reliability of the phase loss protection of the motor.

[0148] In some embodiments, the determination result is: determining that the condition is not satisfied, or determining that the condition is satisfied. The control unit 104 adjusts the preset cumulative fault count value according to the determination result; and determines whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value, including:

[0149] The control unit 104 is further configured to determine whether the determination result is determined to be not satisfied or determined to be satisfied. The specific functions and processing of the control unit 104 are also shown in step S510.

[0150] The control unit 104 is further configured to, if the determination result is that the condition is not satisfied, directly return to re-execute the preset fault search subroutine when the preset cumulative fault count value is equal to 0; and reduce the preset cumulative fault count value by 1 when the preset cumulative fault count value is greater than 0, and then return to re-execute the preset fault search subroutine. The initial value of the preset cumulative fault count value is 0. The specific functions and processing of the control unit 104 are also shown in step S520.

[0151] The control unit 104 is further configured to increase the preset cumulative fault count value by 1 if the determination result is satisfied; and then determine whether the one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value. The specific functions and processing of the control unit 104 are also shown in step S530.

[0152] Fig.12 FIG. 1 is a flow chart of a U-phase failure fault retrieval subroutine in the phase failure protection detection method of the present invention. Fig.12 As shown in FIG. 1 , the process of the phase failure retrieval subroutine taking the U phase as an example includes:

[0153] Step 21, after entering the phase failure fault retrieval subroutine, there are three judgment conditions, and it is determined whether at least one of the three judgment conditions is met: if so, execute step 22; otherwise, if the accumulated fault count value FaultACnt is greater than 0, the accumulated fault count value FaultACnt is reduced by 1, and then return to step 21.

[0154] In step 21, the three determination conditions are: a first determination condition, a second determination condition and a third determination condition.

[0155] Among them, the first judgment condition is: the U phase positive half cycle current is much smaller than the U phase negative half cycle current (Ia_PosAbs <Ia_NegAbs / 4)。

[0156] The second judgment condition is: the negative half-cycle current of phase U is much smaller than the positive half-cycle current of phase U (Ia_NegAbs <Ia_PosAbs / 4)。

[0157] The third judgment condition is: the accumulated value of the U-phase current is much smaller than the accumulated value of the other two-phase currents (Ia_sumAbs<(Ib_sumAbs+Ic_sumAbs) / 4).

[0158] Step 22: add 1 to the accumulated fault count value FaultACnt, and then execute step 23 to implement phase loss detection for the U phase according to the accumulated fault count value FaultACnt.

[0159] In the solution of the present invention, the accumulated fault count value FaultACnt is calculated simultaneously through three judgment conditions, so that the triggering range is wider, and the ability of the program to identify phase loss faults can be improved.

[0160] In some implementations, the control unit 104 determines whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value, including:

[0161] The control unit 104 is further configured to determine whether the adjusted preset cumulative fault count value is greater than a set number of times, wherein the set number of times is, for example, 10 times. The specific functions and processing of the control unit 104 are also referred to step S610.

[0162] The control unit 104 is further configured to return to re-execute the preset fault search subroutine if it is determined that the adjusted preset cumulative fault count value is not greater than the set number of times. The specific functions and processing of the control unit 104 are also shown in step S620.

[0163] The control unit 104 is further configured to determine that one of the three-phase currents of the motor is out of phase if it is determined that the adjusted preset cumulative fault count value is greater than the set number of times; further, initiate a reminder message of the one of the three-phase currents of the motor being out of phase, and control the motor to stop, so as to implement phase-out protection for the motor. The specific functions and processing of the control unit 104 are also shown in step S630.

[0164] like Fig.12As shown, the process of the phase loss fault retrieval subroutine taking the U phase as an example also includes: Step 23, if the accumulated fault count value FaultACnt is greater than 10, the accumulated fault count value FaultACnt is cleared, and a U phase loss fault signal is issued to realize the phase loss detection of the U phase.

[0165] In the solution of the present invention, the accumulated fault count value FaultACnt is increased and decreased through three judgment conditions. When the accumulated fault count value FaultACnt reaches a certain number, such as 10, the phase loss fault protection is triggered to send a fault signal to the main control chip [2]. In this way, the accumulated fault count value FaultACnt is calculated simultaneously through three judgment conditions, and the trigger range is wider, which can improve the ability of the program to identify phase loss faults; by triggering the phase loss protection when the accumulated fault count value FaultACnt reaches a certain number, such as 10, it can prevent the protection from being falsely triggered due to motor phase current fluctuations in extreme situations.

[0166] See also Figures 8 to 12 The example shown in the figure shows the specific control logic of the permanent magnet synchronous motor phase loss protection system, including:

[0167] Step 31: After the motor controller is initialized, the bias voltage and other parameters are collected and ensured to be within the normal error range. The bias voltage should be within the range of 1.65V plus or minus 10% to ensure the accuracy of current sampling. Then, the phase failure protection module [5] is initialized and the phase failure flag is cleared.

[0168] Step 32: After the initialization work is completed, the permanent magnet synchronous motor enters the running state, and the motor controller detects the possible phase loss of the permanent magnet synchronous motor through the phase loss protection detection module [5].

[0169] Taking the U phase as an example, the open-phase protection detection module [5] initializes the AD sampling and collects the current of the U phase of the motor in the AD interrupt. After the collection is completed, it is judged whether the current current cycle has ended. If the current current cycle has not ended, the absolute value of the U-phase current value Ia collected this time is accumulated to the absolute value of the accumulated value of the U-phase current Ia_sumAbs. After calculating Ia_sumAbs, it is judged whether it is the positive half cycle currently. If it is the positive half current cycle currently, the absolute value of Ia is accumulated to the absolute value of the accumulated value of the U-phase current Ia_PosAbs in the positive half current cycle; otherwise, the absolute value of Ia is accumulated to the absolute value of the accumulated value of the U-phase current Ia_NegAbs in the negative half current cycle. Then it is judged again whether the current current cycle has ended. If it has not ended yet, continue the accumulation calculation. If it has ended, enter the fault retrieval subroutine. In the fault retrieval subroutine, the judgment conditions are as follows: 1) The current in the positive half cycle of the U phase is much smaller than the current in the negative half cycle of the U phase (Ia_PosAbs < Ia_NegAbs / 4); 2) The current in the negative half cycle of the U phase is much smaller than the current in the positive half cycle of the U phase (Ia_NegAbs < Ia_PosAbs / 4); 3) The accumulated value of the U-phase current value is much smaller than the accumulated values of the currents of the other two phases (Ia_sumAbs < (Ib_sumAbs + Ic_sumAbs) / 4); After starting the fault retrieval, if the judgment conditions are met, the U-phase fault count value is incremented by 1, otherwise the fault count value is decremented by 1. When the cumulative fault count value FaultACnt is greater than 10, the fault count value is cleared, and at the same time, a U-phase open-phase fault signal is sent to the main control chip [2] to stop the motor.

[0170] In the solution of the present invention, the rotor angle does not need to be read; the open-phase judgment conditions are: the ratio of the accumulated absolute values of the currents in the upper half cycle and the lower half cycle of the single-phase current, and the ratio of the accumulated absolute value of one-phase current to the other two phases; the current sampling method is: compatible with three-phase, two-phase and single-phase current sampling; and it is applicable to both load and no-load conditions at the same time. Taking the phase current data of one current cycle for calculation ensures that the data used includes all the phase current data of the motor from 0 to 360° electrical angle, making the data used for calculation more representative. After accumulating the obtained phase current data and then participating in the calculation and judgment, some instantaneous interference signals can be smoothed out, making the calculation result more accurate. At the same time, under different working environments and load conditions, the instantaneous value of the current may have a large change range, which makes it difficult to set a fixed protection threshold. The accumulated current value can better adapt to different application scenarios by adjusting the integration time and the protection threshold. By calculating the cumulative fault value simultaneously through three judgment conditions, the triggering range is wider, and the ability of the program to identify open-phase faults can be improved. Triggering the open-phase protection by accumulating the fault value to a certain number can prevent mis-triggering of the protection caused by the phase current fluctuation of the motor in extreme cases.

[0171] 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.

[0172] According to an embodiment of the present invention, a motor corresponding to a protection device for the motor is also provided. The motor may include: the protection device for the motor described above.

[0173] Since the processing and functions implemented by the motor 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 will not be repeated here.

[0174] According to an embodiment of the present invention, a computer program product corresponding to a motor is also provided, comprising a computer program, and when the computer program is executed by a processor, the steps of the motor protection method described above are implemented.

[0175] Since the processing and functions implemented by the product of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned motor, 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.

[0176] According to an embodiment of the present invention, a storage medium corresponding to the motor protection method is also provided, wherein 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 steps of the motor protection method described above.

[0177] 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.

[0178] 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.

[0179] 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 protecting a motor, characterized in that: The motor has a three-phase winding; The motor protection method comprises: During the operation of the motor, for each phase winding of the three-phase winding of the motor, the phase current of each phase winding of the motor is obtained; thereby, the three-phase current of the motor is obtained; Determine whether one phase of the three-phase current of the motor is missing based only on the three-phase current of the motor in combination with a preset fault retrieval subroutine; and When it is determined that one phase of the three-phase current of the motor is out of phase, a reminder message of the one phase of the three-phase current of the motor is out of phase is initiated, and the motor is controlled to stop to achieve phase-out protection for the motor.

2. The motor protection method according to claim 1, characterized in that: Determining whether one phase of the three-phase current of the motor is missing is performed based only on the three-phase current of the motor in combination with a preset fault retrieval subroutine, including: Determine whether the current cycle is over; If it is determined that the current current cycle has not ended, then within the current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated current of each phase in the full current cycle, the absolute value of the accumulated current of each phase in the positive half current cycle, and the absolute value of the accumulated current of each phase in the negative half current cycle are calculated, and then return to re-determine whether the current current cycle has ended; in this way, within the current current cycle, the absolute value of the accumulated current of the three-phase current of the full current cycle, the absolute value of the accumulated current of the three-phase current of the positive half current cycle, and the absolute value of the accumulated current of the three-phase current of the negative half current cycle are obtained; If it is determined that the current current cycle has ended, a preset fault retrieval subroutine is executed to determine whether one phase of the three-phase current of the motor is missing by combining the absolute value of the accumulated three-phase current of the full current cycle within the current current cycle, the absolute value of the accumulated three-phase current of the positive half current cycle, and the absolute value of the accumulated three-phase current of the negative half current cycle.

3. The motor protection method according to claim 2, characterized in that: The current cycle includes a positive half current cycle and a negative half current cycle; wherein the positive half current cycle and the negative half current cycle constitute a full current cycle; In the current cycle, for each phase current of the three-phase current of the motor, the absolute value of the accumulated current of each phase in the full current cycle, the absolute value of the accumulated current of each phase in the positive half current cycle, and the absolute value of the accumulated current of each phase in the negative half current cycle are calculated, including: In the current cycle, for each phase current of the three-phase current of the motor, the absolute value of each phase current obtained at the current moment is taken, and the absolute value of the accumulated value of each phase current in the entire current cycle is accumulated; Determine whether the current moment belongs to the positive half current cycle within the current current cycle; If it is determined that the current moment belongs to the positive half current cycle within the current cycle, then after taking the absolute value of each phase current obtained at the current moment, the accumulated value of each phase current in the positive half current cycle is added and taken as the absolute value; If it is determined that the current moment does not belong to the positive half current cycle of the current cycle, the absolute value of each phase current obtained at the current moment is taken, and the absolute value of the accumulated value of each phase current in the negative half current cycle is accumulated.

4. The motor protection method according to claim 2 or 3, characterized in that: For one phase current of the three-phase current of the motor, the absolute value of the accumulated value of the three-phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle are taken, including: the absolute value of the accumulated value of one phase current of the full current cycle in the current current cycle, the absolute value of the accumulated value of one phase current of the positive half current cycle, and the absolute value of the accumulated value of one phase current of the negative half current cycle are taken; Executing a preset fault retrieval subroutine to determine whether one phase of the three-phase current of the motor is missing by combining the absolute value of the accumulated value of the three-phase current of the full current cycle, the absolute value of the accumulated value of the three-phase current of the positive half current cycle, and the absolute value of the accumulated value of the three-phase current of the negative half current cycle in the current cycle, including: Execute a preset fault search subroutine to determine whether one of the three-phase currents of the motor satisfies at least one of the following conditions within the current cycle: the absolute value of the accumulated value of the current of the phase in the positive half current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the negative half current cycle to a set coefficient, the absolute value of the accumulated value of the current of the phase in the negative half current cycle is less than the ratio of the absolute value of the accumulated value of the current of the phase in the positive half current cycle to the set coefficient, and the absolute value of the accumulated value of the current of the phase in the full current cycle is less than the ratio of the sum of the absolute values ​​of the accumulated values ​​of the other two phases in the full current cycle to the set coefficient; wherein the set coefficient is greater than 1; According to the determination result, the preset cumulative fault count value is adjusted; and according to the adjusted preset cumulative fault count value, it is determined whether one phase of the three-phase current of the motor is missing.

5. The motor protection method according to claim 4, characterized in that: The determination result is: determining that the condition is not satisfied, or determining that the condition is satisfied; According to the determination result, adjusting the preset cumulative fault count value; And determining whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value, including: Determining whether the determination result is a determination not to satisfy or a determination to satisfy; If the determination result is that the condition is not satisfied, then when the preset cumulative fault count value is equal to 0, the program returns directly to re-execute the preset fault search subroutine; when the preset cumulative fault count value is greater than 0, the preset cumulative fault count value is reduced by 1, and then the program returns to re-execute the preset fault search subroutine; If the determination result is that the condition is satisfied, the preset cumulative fault count value is increased by 1; thereafter, it is determined whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value.

6. The motor protection method according to claim 5, characterized in that: Determining whether one phase of the three-phase current of the motor is missing according to the adjusted preset cumulative fault count value includes: Determine whether the adjusted preset cumulative fault count value is greater than the set number of times; If it is determined that the adjusted preset cumulative fault count value is not greater than the set number of times, then return to re-execute the preset fault retrieval subroutine; If it is determined that the adjusted preset cumulative fault count value is greater than the set number of times, it is determined that one phase of the three-phase current of the motor is out of phase.

7. A motor protection device, characterized in that: The motor has a three-phase winding; The motor protection device comprises: An acquisition unit is configured to acquire a phase current of each phase winding of the motor for each phase winding of the three-phase winding of the motor during the operation of the motor, thereby obtaining the three-phase current of the motor; A control unit is configured to determine whether one phase of the three-phase current of the motor is missing based only on the three-phase current of the motor in combination with a preset fault retrieval subroutine; and The control unit is also configured to, when determining that one phase of the three-phase current of the motor is missing, initiate a reminder message that the one phase of the three-phase current of the motor is missing, and control the motor to shut down to achieve phase-missing protection for the motor.

8. A motor, characterized in that: include: The motor protection device 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 motor protection method 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 motor protection method according to any one of claims 1 to 6 are implemented.

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