A short-circuit fault real-time diagnosis method for a current source permanent magnet synchronous motor system based on average current error

Abstract

The application is a kind of short-circuit fault real-time diagnosis method of current source permanent magnet synchronous motor system based on average current error. The application relates to the field of motor control technology. The application determines the average value of the absolute value of the given three-phase current in a cycle. The application determines the average value of the actual three-phase current in a cycle. The application determines the average value of the reference current error in a cycle. According to the determined values, the diagnosis variable is determined. According to the diagnosis variable, the switching tube with short-circuit fault is detected and positioned. The application can diagnose and position the switching tube with short-circuit fault in real time. The application is simple and easy to implement, and does not need to add additional voltage sensors, only the actual phase current needs to be fed back.

Description

Technical Field

[0001] This invention relates to the field of motor control technology and is a real-time short-circuit fault diagnosis method for current source type permanent magnet synchronous motor systems based on average current error. Background Technology

[0002] Current source inverters, with their simple topology, good output waveform, and reliable short-circuit protection, have been widely used in motor drive systems. However, current source inverters can break down due to power electronic faults, aging, and other uncontrollable factors during operation. Semiconductor faults account for 34% of power electronic system failures, clearly highlighting the need to incorporate fault diagnosis algorithms to improve system reliability. Rapid detection and location of faulty switches are prerequisites for the normal operation of fault-tolerant systems. Currently, research on inverter switch fault diagnosis mainly focuses on voltage source inverters, with less research on current source inverter fault diagnosis. With the widespread application of current source inverters, further research on their switch fault diagnosis is needed. Summary of the Invention

[0003] This invention calculates the normalized given current error by detecting the three-phase current of a permanent magnet synchronous motor, and uses it as a detection threshold to quickly diagnose and locate the switching transistor with a short circuit fault. The purpose is to improve the safety and reliability of permanent magnet synchronous motor systems powered by current source inverters.

[0004] This invention provides the following technical solutions:

[0005] A current-source type permanent magnet synchronous motor system based on average current error, the system comprising:

[0006] Voltage source, DC-DC converter, inductor L dc Switch S1, Switch S2, Switch S3, Switch S4, Switch S5, Switch S6, Diode D1, Diode D2, Diode D3, Diode D4, Diode D5, Diode D6, Capacitor C f and permanent magnet synchronous motor (PMSM);

[0007] A DC-DC converter is connected to both sides of the voltage source, and an inductor is connected to one end of the DC-DC converter. L dc One end, inductor L dc The other end is connected to one end of switching transistors S1, S3 and S5. The other end of switching transistor S1 is connected to one end of diode D1, the other end of switching transistor S3 is connected to one end of diode D3, and the other end of switching transistor S5 is connected to one end of diode D5.

[0008] The other end of diode D1 is connected to one end of switch S4, the other end of diode D3 is connected to one end of switch S6, and the other end of diode D5 is connected to one end of switch S2; switch S4, switch S6, and switch S2 are respectively connected to the three phases A, B, and C of the permanent magnet synchronous motor PMSM, and capacitors are connected to the connection points respectively. C f ;

[0009] The other end of switch S4 is connected to one end of diode D4, the other end of switch S6 is connected to one end of diode D6, the other end of switch S2 is connected to one end of diode D2, and the other end of the DC-DC converter is connected to the other ends of diodes D4, D6 and D2.

[0010] A real-time short-circuit fault diagnosis method for a current-source permanent magnet synchronous motor system based on average current error is disclosed. The method comprises the following steps:

[0011] Step 1: Determine the average of the absolute values ​​of the given three-phase currents over one cycle;

[0012] Step 2: Determine the average value of the actual three-phase current over one cycle;

[0013] Step 3: Determine the average value of the reference current error over one cycle;

[0014] Step 4: Determine the diagnostic variables based on the values ​​determined in Steps 1 to 3;

[0015] Step 5: Detect and locate the switching transistor that has a short circuit fault based on diagnostic variables.

[0016] Preferably, step 1 specifically comprises:

[0017] The average of the absolute values ​​of a given three-phase current over one cycle is obtained as follows:

[0018]

[0019] in, , , It is a given three-phase current; I m Indicates the magnitude of the phase current; ω It is the frequency of the motor's current;

[0020] The average absolute value of the current in any given phase within one cycle is calculated using the following formula:

[0021]

[0022] in, n = a, b, c.

[0023] Preferably, the average value of the actual three-phase current over one cycle in step 2 is obtained by the following formula:

[0024]

[0025] Preferably, in step 3, the reference current error The average value over a period is obtained by the following formula:

[0026]

[0027] Preferably, the diagnostic variables are obtained by the following formula:

[0028] The diagnostic variable is the average of the errors of three reference currents. The following is generated:

[0029]

[0030] To be applicable to different power conditions, the average reference current error is normalized using the average absolute value of the motor phase current, ultimately determining the diagnostic variable. d n It is given by the following formula:

[0031]

[0032] Due to the given current As a symmetrical sinusoidal current, its average value over one period is 0. (Diagnostic variable) d n Simplified to:

[0033] .

[0034] Preferably, the method further includes setting two auxiliary variables. D n and A n The auxiliary variables are defined as follows:

[0035]

[0036]

[0037] Preferably, if the two short-circuited switches are located at the upper and lower ends of different phases, then d n A phase with a value of 0 is in a normal state; d nThe phase that is not equal to 0 is the faulty phase;

[0038] like d n If the value is greater than 0, then the lower tube of that phase is short-circuited. A n Let L be the value.

[0039] like d n A value less than 0 indicates a short circuit in the upper tube of that phase. A n For H;

[0040] If both short-circuited switches are located at the upper or lower ends of different phases, A n Two phases with the same value are considered faulty phases; and if the two phases have the same value... A n If both are H, then it's a short circuit in the upper pipe; if both phases are... A n If both are L, then the lower pipe is short-circuited.

[0041] A computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement a real-time short-circuit fault diagnosis method for a current-source permanent magnet synchronous motor system based on average current error.

[0042] A computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement a real-time short-circuit fault diagnosis method for a current-source permanent magnet synchronous motor system based on average current error.

[0043] The present invention has the following beneficial effects:

[0044] This invention presents a real-time short-circuit fault diagnosis algorithm for current-source permanent magnet synchronous motor systems based on average current error. By setting a threshold, it can diagnose and locate the switching transistor experiencing a short-circuit fault in real time. This algorithm is simple and easy to implement, requiring no additional voltage sensors and only feedback of the actual phase current. Attached Figure Description

[0045] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 The diagram shows the topology of the permanent magnet synchronous motor system driven by the current source inverter of the present invention.

[0047] Figure 2 The diagram shown is a fault diagnosis scheme diagram of the present invention;

[0048] Figure 3 The flowchart shown is a short-circuit fault diagnosis algorithm of the present invention. Detailed Implementation

[0049] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The present invention will be described in detail below with reference to specific embodiments. Specific Implementation Example 1:

[0052] according to Figures 1 to 3 As shown, the specific optimized technical solution adopted by the present invention to solve the above-mentioned technical problems is: The present invention relates to a real-time diagnosis method for short-circuit faults in a current source type permanent magnet synchronous motor system based on average current error.

[0053] This invention provides a current-source type permanent magnet synchronous motor system based on average current error, the system comprising:

[0054] Voltage source, DC-DC converter, inductor L dc Switch S1, Switch S2, Switch S3, Switch S4, Switch S5, Switch S6, Diode D1, Diode D2, Diode D3, Diode D4, Diode D5, Diode D6, Capacitor C f and permanent magnet synchronous motor (PMSM);

[0055] A DC-DC converter is connected to both sides of the voltage source, and an inductor is connected to one end of the DC-DC converter. L dc One end, inductor L dc The other end is connected to one end of switching transistors S1, S3 and S5. The other end of switching transistor S1 is connected to one end of diode D1, the other end of switching transistor S3 is connected to one end of diode D3, and the other end of switching transistor S5 is connected to one end of diode D5.

[0056] The other end of diode D1 is connected to one end of switch S4, the other end of diode D3 is connected to one end of switch S6, and the other end of diode D5 is connected to one end of switch S2; switch S4, switch S6, and switch S2 are respectively connected to the three phases A, B, and C of the permanent magnet synchronous motor PMSM, and capacitors are connected to the connection points respectively. C f ;

[0057] The other end of switch S4 is connected to one end of diode D4, the other end of switch S6 is connected to one end of diode D6, the other end of switch S2 is connected to one end of diode D2, and the other end of the DC-DC converter is connected to the other ends of diodes D4, D6 and D2.

[0058] This invention can diagnose and locate short-circuit faulty switching transistors in real time by setting a threshold. The algorithm is simple and easy to implement, requiring no additional voltage sensors, only feedback of the actual phase current. Specific Implementation Example 2:

[0060] The only difference between Embodiment 2 and Embodiment 1 of this application is that:

[0061] This invention provides a real-time short-circuit fault diagnosis method for a current-source permanent magnet synchronous motor system based on average current error. The method is implemented using a current-source permanent magnet synchronous motor system based on average current error, the system comprising:

[0062] Voltage source, DC-DC converter, inductor L dc Switch S1, Switch S2, Switch S3, Switch S4, Switch S5, Switch S6, Diode D1, Diode D2, Diode D3, Diode D4, Diode D5, Diode D6, Capacitor C f and permanent magnet synchronous motor (PMSM);

[0063] A DC-DC converter is connected to both sides of the voltage source, and an inductor is connected to one end of the DC-DC converter. L dc One end, inductor L dc The other end is connected to one end of switching transistors S1, S3 and S5. The other end of switching transistor S1 is connected to one end of diode D1, the other end of switching transistor S3 is connected to one end of diode D3, and the other end of switching transistor S5 is connected to one end of diode D5.

[0064] The other end of diode D1 is connected to one end of switch S4, the other end of diode D3 is connected to one end of switch S6, and the other end of diode D5 is connected to one end of switch S2; switch S4, switch S6, and switch S2 are respectively connected to the three phases A, B, and C of the permanent magnet synchronous motor PMSM, and capacitors are connected to the connection points respectively. C f ;

[0065] The other end of switch S4 is connected to one end of diode D4, the other end of switch S6 is connected to one end of diode D6, the other end of switch S2 is connected to one end of diode D2, and the other end of the DC-DC converter is connected to the other ends of diodes D4, D6, and D2. The method includes the following steps:

[0066] Step 1: Determine the average of the absolute values ​​of the given three-phase currents over one cycle;

[0067] Step 2: Determine the average value of the actual three-phase current over one cycle;

[0068] Step 3: Determine the average value of the reference current error over one cycle;

[0069] Step 4: Determine the diagnostic variables based on the values ​​determined in Steps 1 to 3;

[0070] Step 5: Detect and locate the switching transistor that has a short circuit fault based on diagnostic variables.

[0071] This invention can diagnose and locate short-circuit faulty switching transistors in real time by setting a threshold. The algorithm is simple and easy to implement, requiring no additional voltage sensors, only feedback of the actual phase current. Specific Implementation Example 3:

[0073] The only difference between Embodiment 3 and Embodiment 2 of this application is that:

[0074] Step 1 specifically involves:

[0075] The average of the absolute values ​​of a given three-phase current over one cycle is obtained as follows:

[0076]

[0077] in, , , It is a given three-phase current; I m Indicates the magnitude of the phase current; ω It is the frequency of the motor's current;

[0078] The average absolute value of the current in any given phase within one cycle is calculated using the following formula:

[0079]

[0080] in, n = a, b, c. Specific Implementation Example 4:

[0082] The only difference between Embodiment 4 and Embodiment 3 of this application is that:

[0083] The average value of the actual three-phase current over one cycle in step 2 is obtained by the following formula:

[0084] Specific Implementation Example 5:

[0086] The difference between Embodiment 5 and Embodiment 4 of the present invention lies only in:

[0087] Reference current error in step 3 The average value over a period is obtained by the following formula:

[0088] Specific Implementation Example Six:

[0090] The difference between Embodiment Six and Embodiment Five of the present invention lies only in:

[0091] Diagnostic variables are obtained using the following formula:

[0092] The diagnostic variable is the average of the errors of three reference currents. The following is generated:

[0093]

[0094] To be applicable to different power conditions, the average reference current error is normalized using the average absolute value of the motor phase current, ultimately determining the diagnostic variable. d n It is given by the following formula:

[0095]

[0096] Due to the given current As a symmetrical sinusoidal current, its average value over one period is 0. (Diagnostic variable) d n Simplified to:

[0097] . Specific Implementation Example 7:

[0099] The difference between Embodiment Seven and Embodiment Six of the present invention lies only in:

[0100] The method also includes setting two auxiliary variables. D n and A n The auxiliary variables are defined as follows:

[0101]

[0102] Specific Implementation Example 8:

[0104] The difference between Embodiment 8 and Embodiment 7 of the present invention lies only in:

[0105] If the two short-circuited switches are located at the upper and lower ends of different phases, then d n A phase with a value of 0 is in a normal state; d n The phase that is not equal to 0 is the faulty phase;

[0106] like d n If the value is greater than 0, then the lower tube of that phase is short-circuited. A n Let L be the value.

[0107] like d n A value less than 0 indicates a short circuit in the upper tube of that phase. A n For H;

[0108] If both short-circuited switches are located at the upper or lower ends of different phases, A n Two phases with the same value are considered faulty phases; and if the two phases have the same value... A n If both are H, then it's a short circuit in the upper pipe; if both phases are... A n If both are L, then the lower pipe is short-circuited. Specific Implementation Example Nine:

[0110] The difference between Embodiment Nine and Embodiment Eight of the present invention lies only in:

[0111] The present invention provides a computer-readable storage medium having a computer program stored thereon, which is executed by a processor to implement a real-time short-circuit fault diagnosis method for a current-source permanent magnet synchronous motor system based on average current error. Specific Implementation Example 10:

[0113] The only difference between Embodiment 10 and Embodiment 9 of the present invention is that:

[0114] The present invention provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a real-time short-circuit fault diagnosis method for a current source type permanent magnet synchronous motor system based on average current error. Specific Implementation Example Eleven:

[0116] The only difference between Embodiment Eleven and Embodiment Ten of this invention is that:

[0117] This invention provides a current-source type permanent magnet synchronous motor system based on average current error, the system comprising:

[0118] Voltage source, DC-DC converter, inductor L dc Switch S1, Switch S2, Switch S3, Switch S4, Switch S5, Switch S6, Diode D1, Diode D2, Diode D3, Diode D4, Diode D5, Diode D6, Capacitor C f and permanent magnet synchronous motor (PMSM);

[0119] A DC-DC converter is connected to both sides of the voltage source, and an inductor is connected to one end of the DC-DC converter. L dc One end, inductor L dc The other end is connected to one end of switching transistors S1, S3 and S5. The other end of switching transistor S1 is connected to one end of diode D1, the other end of switching transistor S3 is connected to one end of diode D3, and the other end of switching transistor S5 is connected to one end of diode D5.

[0120] The other end of diode D1 is connected to one end of switch S4, the other end of diode D3 is connected to one end of switch S6, and the other end of diode D5 is connected to one end of switch S2; switch S4, switch S6, and switch S2 are respectively connected to the three phases A, B, and C of the permanent magnet synchronous motor PMSM, and capacitors are connected to the connection points respectively. C f ;

[0121] The other end of switch S4 is connected to one end of diode D4, the other end of switch S6 is connected to one end of diode D6, the other end of switch S2 is connected to one end of diode D2, and the other end of the DC-DC converter is connected to the other ends of diodes D4, D6 and D2.

[0122] Based on the above system, this invention provides a real-time short-circuit fault diagnosis algorithm for a current-source permanent magnet synchronous motor system based on average current error. The method includes the following steps:

[0123] Step 1: Calculate the average of the absolute values ​​of the given three-phase currents over one cycle;

[0124] Step 2: Calculate the average value of the actual three-phase current over one cycle;

[0125] Step 3: Calculate the average value of the reference current error over one cycle;

[0126] Step 4: Combine Step 1, Step 2, and Step 3 to determine the diagnostic variables;

[0127] Step 5: Detect and locate the switching transistor that has a short-circuit fault based on diagnostic variables;

[0128] In step one, the average of the absolute values ​​of the given three-phase currents over one cycle is obtained as follows:

[0129]

[0130] in , , It is a given three-phase current; I m Indicates the magnitude of the current; ω It is the frequency of the motor's current.

[0131] The average absolute value of the phase current of any given phase within one cycle can be calculated using the following formula:

[0132]

[0133] in, n = a, b, c.

[0134] With the given current of phase A For example, in the first half of the cycle, It is positive; in the second half of the cycle, It is negative. Therefore, The absolute values ​​are shown below:

[0135]

[0136] By combining the above formulas, we can obtain the answer. The average of the absolute values ​​over a period of time is shown below:

[0137]

[0138] The given current of phase B and the given current of phase C The average absolute value and same.

[0139] In step two, the average value of the actual three-phase current over one cycle is obtained by the following formula:

[0140]

[0141] In step three, the reference current error The average value over a period is obtained by the following formula:

[0142]

[0143] Furthermore, in step four, the diagnostic variables are obtained using the following formula:

[0144] The diagnostic variable is the average of the errors of three reference currents. The following is generated:

[0145]

[0146] To enable this method to be applied to different power conditions, the average reference current error is normalized using the average absolute value of the motor phase currents. Therefore, the final diagnostic variable... d n It is given by the following formula:

[0147]

[0148] Due to the given current Since it is a symmetrical sinusoidal current, its average value over one period is 0. (Diagnostic variable) d n It can be simplified to:

[0149]

[0150] The main advantages of this invention are: it is a real-time short-circuit fault diagnosis algorithm for current-source permanent magnet synchronous motor systems based on average current error. By setting a threshold, it can diagnose and locate the switching transistors experiencing short-circuit faults in real time. This algorithm is simple and easy to implement, requiring no additional voltage sensors, only feedback of the actual phase current.

[0151] From the above derivation process, it can be concluded that when the current source inverter does not experience a short-circuit fault, the diagnostic variables... d a = d b = d c =0. If switch S1 on phase A is short-circuited. i a >0, therefore diagnostic variable d a <0. Due to a short circuit in S1, ib and i c The waveform mostly appears in the negative half-cycle, with only a small portion appearing in the positive half-cycle. The positive half-cycle portion can be ignored; in this case, the diagnostic variable... d b and d c Greater than 0. The analysis process for other single-transistor short-circuit faults is similar. Therefore, a detection threshold needs to be set for single-transistor short-circuit faults. k f When diagnostic variables d a , d b and d c The absolute value has a value greater than 1. k f Furthermore, if all three values ​​are not equal to 0, it proves that only one switch has a short-circuit fault. The sign of the diagnostic variable for the short-circuited phase is opposite to the sign of the diagnostic variables for the other two phases. Finally, based on the sign of the diagnostic variables, it is determined whether the upper switch or the lower switch is short-circuited. The single-switch short-circuit detection rules are shown in Table 1.

[0152] Table 1 Single Switch Short Circuit Fault Detection Table

[0153]

[0154] The conduction of both the upper and lower transistors in one bridge arm represents an effective zero-vector state for the current-source inverter, at which point the inverter's output current is zero. Therefore, the multi-switch short-circuit fault detection studied in this invention mainly involves the following three scenarios: First, both short-circuited switches are located at the upper or lower ends of different phases; second, the two short-circuited switches are located at the upper and lower ends of different phases, respectively; third, the three short-circuited switches are located in three different bridge arms, and these three switches are not simultaneously located on the upper or lower side. To achieve the detection of the above multi-switch faults, an additional detection threshold needs to be added. k m It should be noted that k m < k f The specific analysis is as follows.

[0155] If multiple switches are short-circuited, three diagnostic variables d a , d b , d c At least one diagnostic variable has an absolute value greater than k mTherefore, this can serve as a characteristic for determining multiple short circuits. If any of the three diagnostic variables equals 0, it indicates that the two short-circuited switches are located at the upper and lower ends of different phases, respectively; if none of the three diagnostic variables equals 0, it indicates that both short-circuited switches are located at the upper or lower ends of different phases. Finally, based on the signs of the three diagnostic variables, the faulty switch can be accurately identified.

[0156] Set two auxiliary variables D n and A n The auxiliary variables are defined as follows:

[0157]

[0158]

[0159] Table 2. Multi-switch short-circuit fault detection table

[0160]

[0161] As can be seen from Table 2, if the two short-circuited switches are located at the upper and lower ends of different phases, then... d n A phase with a value of 0 is in a normal state; d n The phase ≠ 0 is the faulty phase; then if d n A value greater than 0 indicates a short circuit in the lower tube of that phase. A n Let L be the value of L; if d n A value less than 0 indicates a short circuit in the upper tube of that phase. A n For H. If both short-circuited switches are located at the upper or lower ends of different phases, A n Two phases with the same value are considered faulty phases. And if the two phases... A n If both are H, then it's a short circuit in the upper pipe; if both phases are... A n If both are L, then the lower pipe is short-circuited.

[0162] The real-time short-circuit fault diagnosis algorithm for current-source permanent magnet synchronous motor systems based on average current error proposed in this invention is summarized as follows.

[0163] If all three diagnostic variables are equal to 0, it proves that none of the switches are short-circuited and the system is operating normally. If the absolute value of one of the three diagnostic variables is greater than 0, then the system is operating normally. k fIf all three values ​​are not equal to 0, this indicates a short circuit in one of the switching transistors. Next, locate the faulty switch according to Table 1. The absolute value of one of the three diagnostic variables is greater than... k m Less than k f This indicates that multiple switching transistors are short-circuited. Then, according to... A n It can locate all faulty switches. The diagnostic process of this algorithm is as follows: Figure 3 As shown.

[0164] This invention can diagnose and locate short-circuit faulty switching transistors in real time by setting a threshold. The algorithm is simple and easy to implement, requiring no additional voltage sensors, only feedback of the actual phase current.

[0165] The above description is merely a preferred embodiment of a real-time short-circuit fault diagnosis method for a current-source permanent magnet synchronous motor system based on average current error. The scope of protection for this method is not limited to the above embodiments; all technical solutions falling within this framework are within the scope of protection of this invention. It should be noted that for those skilled in the art, any improvements and variations made without departing from the principles of this invention should also be considered within the scope of protection of this invention.

Claims

1. A real-time short-circuit fault diagnosis method for a current-source permanent magnet synchronous motor system based on average current error, the method being implemented based on a current-source permanent magnet synchronous motor system based on average current error, the system comprising: Voltage source, DC-DC converter, inductor L dc Switch S1, Switch S2, Switch S3, Switch S4, Switch S5, Switch S6, Diode D1, Diode D2, Diode D3, Diode D4, Diode D5, Diode D6, Capacitor C f and permanent magnet synchronous motor (PMSM); A DC-DC converter is connected to both sides of the voltage source, and an inductor is connected to one end of the DC-DC converter. L dc One end, inductor L dc The other end is connected to one end of switching transistors S1, S3 and S5. The other end of switching transistor S1 is connected to one end of diode D1, the other end of switching transistor S3 is connected to one end of diode D3, and the other end of switching transistor S5 is connected to one end of diode D5. The other end of diode D1 is connected to one end of switch S4, the other end of diode D3 is connected to one end of switch S6, and the other end of diode D5 is connected to one end of switch S2; switch S4, switch S6, and switch S2 are respectively connected to the three phases A, B, and C of the permanent magnet synchronous motor PMSM, and capacitor C is connected to each connection point. f ; The other end of switch S4 is connected to one end of diode D4, the other end of switch S6 is connected to one end of diode D6, the other end of switch S2 is connected to one end of diode D2, and the other end of the DC-DC converter is connected to the other ends of diodes D4, D6, and D2. The method is characterized by the following steps: Step 1: Determine the average of the absolute values ​​of the given three-phase currents over one cycle; Step 2: Determine the average value of the actual three-phase current over one cycle; Step 3: Determine the average value of the reference current error over one cycle; Step 4: Determine the diagnostic variables based on the values ​​determined in Steps 1 to 3; Step 5: Detect and locate the switching transistor that has a short circuit fault based on diagnostic variables.

2. The method according to claim 1, characterized in that: Step 1 specifically involves: The average of the absolute values ​​of a given three-phase current over one cycle is obtained as follows: in, , , It is a given three-phase current; I m Indicates the magnitude of the phase current; ω It is the frequency of the motor's current; The average absolute value of the current in any given phase within one cycle is calculated using the following formula: in, n = a, b, c.

3. The method according to claim 2, characterized in that: The average value of the actual three-phase current over one cycle in step 2 is obtained by the following formula: 。 4. The method according to claim 3, characterized in that: Reference current error in step 3 The average value over a period is obtained by the following formula: 。 5. The method according to claim 4, characterized in that: Diagnostic variables are obtained using the following formula: The diagnostic variable is the average of the errors of three reference currents. The following is generated: To be applicable to different power conditions, the average reference current error is normalized using the average absolute value of the motor phase current, ultimately determining the diagnostic variable. d n It is given by the following formula: Due to the given current As a symmetrical sinusoidal current, its average value over one period is 0. (Diagnostic variable) d n Simplified to: 。 6. The method according to claim 5, characterized in that: The method also includes setting two auxiliary variables. D n and A n The auxiliary variables are defined as follows: 。 7. The method according to claim 6, characterized in that: If the two short-circuited switches are located at the upper and lower ends of different phases, then d n A phase with a value of 0 is in a normal state; d n The phase that is not equal to 0 is the faulty phase; like d n If the value is greater than 0, then the lower tube of that phase is short-circuited. A n Let L be the value. like d n A value less than 0 indicates a short circuit in the upper tube of that phase. A n For H; If both short-circuited switches are located at the upper or lower ends of different phases, A n Two phases with the same value are considered faulty phases; and if the two phases have the same value... A n If both are H, then it's a short circuit in the upper pipe; if both phases are... A n If both are L, then the lower pipe is short-circuited.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the method as claimed in any one of claims 1-7.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the method of any one of claims 1-7.

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