Method and apparatus for controlling power amplifier, maglev system and storage medium

Abstract

The application discloses a kind of control method, device, magnetic suspension system and storage medium of power amplifier, the method includes: the current of the main circuit of electromagnetic bearing power amplifier detected by bus current detection module is recorded as the bus current of direct-current power supply;The current of the corresponding bearing coil of electromagnetic bearing detected by the coil current detection module at each bearing coil of electromagnetic bearing is recorded as the coil current of each bearing coil of electromagnetic bearing;According to the bus current of direct-current power supply and the coil current of each bearing coil of electromagnetic bearing, the fault diagnosis of electromagnetic bearing power amplifier, n coil current detection modules and bus current detection module is carried out.The scheme, by the fault diagnosis of power amplifier according to bus current and coil current, the fault condition of power amplifier can be determined in time, and it is favorable to improve the reliability of magnetic suspension motor control system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnetic suspension, and particularly relates to a control method and device of a power amplifier, a magnetic suspension system and a storage medium, in particular to a fault diagnosis method applied to a switching power amplifier (such as an electromagnetic bearing power amplifier), a fault diagnosis device applied to a switching power amplifier (such as an electromagnetic bearing power amplifier), a magnetic suspension system (such as a magnetic suspension motor control system) with the fault diagnosis device, and a storage medium storing a control instruction of the fault diagnosis method. BACKGROUND

[0002] In the magnetic suspension motor control system, the controller compares the collected coil current signal with the given current signal, and through the current loop algorithm module, the driving circuit and the power amplifier and the like, the coil obtains the required current for control, so as to control the size of the magnetic suspension bearing electromagnetic force to make the rotor suspended at the given position. When the power amplifier fails, the magnetic suspension bearing electromagnetic force will be out of control and the rotor cannot be stably suspended, and in serious cases, the protection bearing will be damaged, the rotor will be worn and the like, which seriously affects the reliability of the magnetic suspension motor control system.

[0003] The above content is only used to assist in understanding the technical solutions of the application, and does not represent the acknowledgement of the above content as prior art. SUMMARY

[0004] The application aims to provide a control method and device of a power amplifier, a magnetic suspension system and a storage medium, to solve the problem that when the power amplifier in the magnetic suspension motor control system fails, the magnetic suspension bearing electromagnetic force will be out of control and the rotor cannot be stably suspended, and even the protection bearing will be damaged, the rotor will be worn and the like, which seriously affects the reliability of the magnetic suspension motor control system, to achieve the effect that the power amplifier is diagnosed for faults according to the bus current and the coil current, the fault condition of the power amplifier can be determined in time, the reliability of the magnetic suspension motor control system is not affected due to the failure of the power amplifier which is not found in time, and the reliability of the magnetic suspension motor control system is improved.

[0005] The application provides a power amplifier control method, the power amplifier is applied to a magnetic suspension motor control system and serves as an electromagnetic bearing power amplifier; the electromagnetic bearing power amplifier comprises n power amplifier modules, wherein n is a positive integer; the n power amplifier modules are arranged in parallel between the positive and negative poles of a direct current power supply on the input side of the electromagnetic bearing power amplifier; a bus current detection module is arranged between the positive pole of the direct current power supply and the n power amplifier modules; the bus current detection module is configured to detect the current of the main circuit of the electromagnetic bearing power amplifier; a coil current detection module is arranged between each power amplifier module and the corresponding bearing coil of the electromagnetic bearing; the coil current detection module is configured to detect the current of the corresponding bearing coil of the electromagnetic bearing; the power amplifier control method comprises the following steps: obtaining the current of the main circuit of the electromagnetic bearing power amplifier detected by the bus current detection module, which is recorded as the bus current of the direct current power supply; obtaining the current of the corresponding bearing coil of the electromagnetic bearing detected by the coil current detection module at each bearing coil of the electromagnetic bearing, which is recorded as the coil current of each bearing coil of the electromagnetic bearing; and performing fault diagnosis on the electromagnetic bearing power amplifier, the n coil current detection modules and the bus current detection module according to the bus current of the direct current power supply and the coil current of each bearing coil of the electromagnetic bearing.

[0006] In some embodiments, each power amplifier module comprises a power switch module and a freewheeling module; the power switch module comprises a first switch tube module and a second switch tube module; the freewheeling module comprises a first diode module and a second diode module; wherein the positive pole of the direct current power supply is connected to the first connection end of the first switch tube module and the cathode of the first diode module in each power amplifier module through the bus current detection module; the negative pole of the direct current power supply is connected to the anode of the second diode module and the second connection end of the second switch tube module in each power amplifier module; the second connection end of the first switch tube module in each power amplifier module is connected to the cathode of the second diode module; the anode of the first diode module in each power amplifier module is connected to the first connection end of the second switch tube module; the corresponding coil current detection module and the corresponding bearing coil of the electromagnetic bearing are arranged between the second connection end of the first switch tube module and the anode of the first diode module in each power amplifier module; the fault of the electromagnetic bearing power amplifier includes any of the following faults: the fault of any one of the first switch tube module and the second switch tube module, the fault of any one of the bus current detection module and the n coil current detection modules.

[0007] In some embodiments, the fault diagnosis of the electromagnetic bearing power amplifier, the n coil current detection modules, and the bus current detection module is performed according to the bus current of the direct current power supply and the coil current of each bearing coil of the electromagnetic bearing, including: the fault diagnosis of the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module is performed according to the bus current of the direct current power supply and the coil current of the current bearing coil of the electromagnetic bearing; wherein the current power amplifier module is one of the n power amplifier modules to be currently diagnosed; the current bearing coil of the electromagnetic bearing is one of the n bearing coils of the electromagnetic bearing corresponding to the current power amplifier module; wherein the fault diagnosis of the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module is performed according to the bus current of the direct current power supply and the coil current of the current bearing coil of the electromagnetic bearing, including: determining the change value of the coil current detected by the current coil current detection module within a set control period, and determining the current difference value of the bus current and the n coil currents detected by the n coil current detection modules; the fault diagnosis of the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module is performed according to the current coil current detected by the current coil current detection module and the last coil current, the change value of the coil current detected by the current coil current detection module, and the current difference value of the bus current and the n coil currents detected by the n coil current detection modules; wherein the current coil current is the coil current of the current bearing coil detected by the current coil current detection module at the current detection time; the last coil current is the coil current of the current bearing coil detected by the current coil current detection module at the last detection time.

[0008] In some embodiments, wherein the variation of the coil current detected by the current coil current detection module in a set control period is determined, including: determining the charging time variation rate and the discharging time variation rate of the coil current detected by the current coil current detection module; combining the charging state duty cycle and the discharging state duty cycle of the electromagnetic bearing power amplifier, and the set control period, the product of the charging state duty cycle and the charging time variation rate, and the sum of the product of the discharging state duty cycle and the discharging time variation rate, and the value obtained by multiplying the control period, is determined as the variation of the coil current detected by the current coil current detection module; and / or, determining the current difference value of the bus current and the n coil currents detected by the n coil current detection modules, including: determining the sum of the n coil currents detected by the n coil current detection modules; wherein the sum of the n coil currents detected by the n coil current detection modules is the first total current value or the second total current value; the difference between the bus current and the first total current value is determined as the first total current difference value; the difference between the bus current and the second total current value is determined as the second total current difference value; and the first total current difference value or the second total current difference value is taken as the current difference value of the bus current and the n coil currents detected by the n coil current detection modules; wherein the first total current value refers to the sum of the product of the coil current detected by the first coil current detection module and the corresponding power amplifier module switch signal, to the product of the coil current detected by the n coil current detection module and the corresponding power amplifier module switch signal; or, the second total current value refers to the sum of the product of the coil current detected by the first coil current detection module and the corresponding power amplifier module switch signal to the product of the coil current detected by the m-1 coil current detection module and the corresponding power amplifier module switch signal, the sum of the product of the coil current detected by the m+1 coil current detection module and the corresponding power amplifier module switch signal to the product of the coil current detected by the n coil current detection module and the corresponding power amplifier module switch signal, and the sum of the coil current detected by the m coil current detection module, denoted as the second total current value.

[0009] In some embodiments, the fault diagnosis of the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module is performed according to the current coil current detected by the current coil current detection module and the previous coil current, the change value of the coil current detected by the current coil current detection module, and the current difference value between the bus current and the n coil currents detected by the n coil current detection modules, including: determining the absolute value of the difference between the current coil current detected by the current coil current detection module and the previous coil current detected by the current coil current detection module and the change value of the coil current detected by the current coil current detection module, denoted as a first current difference value; determining whether the first current difference value is greater than a set first error threshold; if the first current difference value is greater than the first error threshold, determining that the switch tube module in the current power amplifier module or the current coil current detection module is faulty, and determining the fault type according to the bus current and the second total current difference value; if the first current difference value is less than or equal to the first error threshold, determining that neither the switch tube module in the current power amplifier module nor the current coil current detection module is faulty, and determining whether the bus current detection module is faulty according to the bus current and the first total current difference value.

[0010] In some embodiments, wherein the fault type is determined according to the bus current and the second total current difference value, including: determining the absolute value of the difference between the bus current and the second total current difference value, denoted as a second current difference value; determining whether the second current difference value is less than or equal to a set second error threshold; if the second current difference value is less than or equal to the second error threshold, determining that the switch tube module in the current power amplifier module is faulty; if the second current difference value is greater than the second error threshold, determining that the current coil current detection module is faulty; and / or, determining whether the bus current detection module is faulty according to the bus current and the first total current difference value, including: determining the absolute value of the difference between the bus current and the first total current difference value, denoted as a third current difference value; determining whether the third current difference value is less than or equal to a set second error threshold; if the third current difference value is less than or equal to the second error threshold, determining that neither the switch tube module in the current power amplifier module, the current coil current detection module, nor the bus current detection module is faulty; if the third current difference value is greater than the second error threshold, determining that the bus current detection module is faulty.

[0011] In some embodiments, further comprising: if any one of the n coil current detection modules fails, determining a sum of products of coil currents detected by the remaining coil current detection modules of the n coil current detection modules and corresponding switch signals of the n power amplifier modules, denoted as a third total current value; determining a difference between the bus current and the third total current value as a fault-tolerant current of the any one of the coil current detection modules in a failure condition; and controlling the any one of the coil current detection modules corresponding to the bearing coil to operate according to the fault-tolerant current.

[0012] In some embodiments, further comprising: if any one of the n coil current detection modules fails, determining a sum of products of coil currents detected by the remaining coil current detection modules of the n coil current detection modules and corresponding switch signals of the n power amplifier modules, denoted as a third total current value; determining a difference between the bus current and the third total current value as a fault-tolerant current of the any one of the coil current detection modules in a failure condition; and controlling the any one of the coil current detection modules corresponding to the bearing coil to operate according to the fault-tolerant current.

[0013] In some embodiments, each of the power amplifier modules comprises: a power switch module and a freewheeling module; the power switch module comprises: a first switch tube module and a second switch tube module; the freewheeling module comprises: a first diode module and a second diode module; wherein the positive pole of the direct current power supply is connected to the first connection end of the first switch tube module and the cathode of the first diode module in each of the power amplifier modules through the bus current detection module; the negative pole of the direct current power supply is connected to the anode of the second diode module and the second connection end of the second switch tube module in each of the power amplifier modules; the second connection end of the first switch tube module in each of the power amplifier modules is connected to the cathode of the second diode module; the anode of the first diode module in each of the power amplifier modules is connected to the first connection end of the second switch tube module; the corresponding coil current detection module and the corresponding bearing coil of the electromagnetic bearing are arranged between the second connection end of the first switch tube module and the anode of the first diode module in each of the power amplifier modules; the failure of the electromagnetic bearing power amplifier comprises any of the following failures: the failure of any of the first switch tube module and the second switch tube module, the failure of any of the bus current detection module and the n coil current detection modules.

[0014] In some embodiments, the control unit performs fault diagnosis on the electromagnetic bearing power amplifier, n coil current detection modules, and the bus current detection module based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing. This includes: performing fault diagnosis on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module based on the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing; wherein, the current power amplifier module is one of the n power amplifier modules currently undergoing fault diagnosis; the current bearing coil of the electromagnetic bearing is one of the n bearing coils of the electromagnetic bearing that corresponds to the current power amplifier module; wherein, the control unit performs fault diagnosis on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module based on the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing. Fault diagnosis is performed on the current coil current detection module at the front bearing coil and the bus current detection module, including: determining the change value of the coil current detected by the current coil current detection module within a set control cycle, and determining the current difference between the bus current and the n coil currents detected by the n coil current detection modules; based on the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module; wherein, the current coil current is the coil current of the current bearing coil detected by the current coil current detection module at the current detection time; the previous coil current is the coil current of the current bearing coil detected by the current coil current detection module at the previous detection time.

[0015] In some embodiments, the control unit determines the variation value of the coil current detected by the current detection module in a set control period, including: determining the charging time variation rate and the discharging time variation rate of the coil current detected by the current detection module; combining the charging state duty cycle and the discharging state duty cycle of the electromagnetic bearing power amplifier, and the set control period, and multiplying the product of the charging state duty cycle and the charging time variation rate, and the product of the discharging state duty cycle and the discharging time variation rate, and the value obtained by multiplying the control period, to determine the variation value of the coil current detected by the current detection module; and / or the control unit determines the current difference value of the bus current and the n coil currents detected by the n coil current detection modules, including: determining the sum of the n coil currents detected by the n coil current detection modules; wherein the sum of the n coil currents detected by the n coil current detection modules is the first total current value or the second total current value; determining the difference value of the bus current and the first total current value as the first total current difference value; determining the difference value of the bus current and the second total current value as the second total current difference value; and taking the first total current difference value or the second total current difference value as the current difference value of the bus current and the n coil currents detected by the n coil current detection modules; wherein the first total current value refers to the sum of the product of the coil current detected by the first coil current detection module and the corresponding power amplifier module switch signal, and the product of the coil current detected by the n coil current detection module and the corresponding power amplifier module switch signal; or the second total current value refers to the sum of the product of the coil current detected by the first coil current detection module and the corresponding power amplifier module switch signal, and the product of the coil current detected by the m-1 coil current detection module and the corresponding power amplifier module switch signal, the sum of the product of the coil current detected by the m+1 coil current detection module and the corresponding power amplifier module switch signal, and the product of the coil current detected by the n coil current detection module and the corresponding power amplifier module switch signal, and the sum of the coil current detected by the m coil current detection module, which is referred to as the second total current value.

[0016] In some embodiments, the control unit, according to the current coil current detected by the current coil current detection module, the previous coil current, the variation of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules, performs fault diagnosis on the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module, including: determining the absolute value of the difference between the current coil current detected by the current coil current detection module and the previous coil current detected by the current coil current detection module, and the variation of the coil current detected by the current coil current detection module, denoted as a first current difference; determining whether the first current difference is greater than a first error threshold; if the first current difference is greater than the first error threshold, determining that the switch tube module in the current power amplifier module or the current coil current detection module is faulty, and determining the fault type according to the bus current and the second total current difference; if the first current difference is less than or equal to the first error threshold, determining that the switch tube module in the current power amplifier module and the current coil current detection module are not faulty, and determining whether the bus current detection module is faulty according to the bus current and the first total current difference.

[0017] In some embodiments, wherein the control unit determines the fault type according to the bus current and the second total current difference, including: determining the absolute value of the difference between the bus current and the second total current difference, denoted as a second current difference; determining whether the second current difference is less than or equal to a second error threshold; if the second current difference is less than or equal to the second error threshold, determining that the switch tube module in the current power amplifier module is faulty; if the second current difference is greater than the second error threshold, determining that the current coil current detection module is faulty; and / or, the control unit determines whether the bus current detection module is faulty according to the bus current and the first total current difference, including: determining the absolute value of the difference between the bus current and the first total current difference, denoted as a third current difference; determining whether the third current difference is less than or equal to a second error threshold; if the third current difference is less than or equal to the second error threshold, determining that the switch tube module in the current power amplifier module, the current coil current detection module, and the bus current detection module are not faulty; if the third current difference is greater than the second error threshold, determining that the bus current detection module is faulty.

[0018] In some embodiments, the control unit is further configured to, if any one of the n coil current detection modules is faulty, determine a sum of products of coil currents detected by the remaining coil current detection modules of the n coil current detection modules and corresponding switch signals of the power amplifier modules, denoted as a third total current value; the control unit is further configured to determine a difference between the bus current and the third total current value as a fault-tolerant current of the any one coil current detection module in a fault condition; and the control unit is further configured to control the corresponding bearing coil of the any one coil current detection module to work according to the fault-tolerant current.

[0019] In another aspect, the application provides a magnetic suspension system, which is matched with the above-mentioned device and comprises the control device of the power amplifier.

[0020] In another aspect, the application provides a storage medium, which comprises a stored program, wherein when the program is executed, the device where the storage medium is located performs the control method of the power amplifier.

[0021] Therefore, the scheme of the application can detect the bus current of the power amplifier by arranging a current sensor on the bus of the power amplifier, detect the corresponding coil current by the current sensor at each coil of the power amplifier, and then realize the diagnosis of the fault of the current sensor and the open circuit fault of the power switch according to the relationship between the coil current and the target current and the relationship between the coil current and the bus current, so as to realize the timely determination of the fault condition of the power amplifier, thereby realizing the fault diagnosis of the power amplifier according to the bus current and the coil current, determining the fault condition of the power amplifier in time, avoiding the failure to discover the influence on the reliability of the magnetic suspension motor control system due to the failure of the power amplifier, and improving the reliability of the magnetic suspension motor control system.

[0022] Further, the scheme of the application can realize the fault-tolerant operation under the single current sensor fault by replacing the current detected by the faulty sensor with the fault-tolerant current, and further improve the reliability of the magnetic suspension motor control system.

[0023] Other features and advantages of the application will be described in the following description, and some will become apparent from the description, or will be learned through practice of the application.

[0024] The technical scheme of the application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a flowchart of an embodiment of the control method of the power amplifier of the application;

[0026] Figure 2 Flow chart of one embodiment of the method of the present application for fault diagnosis of the switch tube module, the current coil current detection module and the bus current detection module in the current power amplifier module according to the bus current and the coil current of the current bearing coil;

[0027] Figure 3 Flow chart of one embodiment of the method of the present application for determining the variation of the coil current detected by the current coil current detection module in the set control period;

[0028] Figure 4 Flow chart of one embodiment of the method of the present application for determining the current difference between the bus current and the n coil currents detected by the n coil current detection modules;

[0029] Figure 5 Flow chart of one embodiment of the method of the present application for fault diagnosis of the switch tube module, the current coil current detection module at the current bearing coil and the bus current detection module according to the current coil current and the previous coil current, the variation of the coil current detected by the current coil current detection module and the current difference between the bus current and the n coil currents;

[0030] Figure 6 Flow chart of one embodiment of the method of the present application for determining the fault type according to the bus current and the second total current difference;

[0031] Figure 7 Flow chart of one embodiment of the method of the present application for determining whether the bus current detection module is faulty according to the bus current and the first total current difference;

[0032] Figure 8 Flow chart of one embodiment of the method of the present application for controlling the fault-tolerant operation of the electromagnetic bearing power amplifier in the case of any coil current detection module fault;

[0033] Figure 9 Structural schematic diagram of one embodiment of the control device of the power amplifier of the present application;

[0034] Figure 10 Structural schematic diagram of one embodiment of the power supply part of the magnetic levitation motor control system in the related scheme;

[0035] Figure 11 Structural schematic diagram of one embodiment of the power amplifier in the scheme of the present application;

[0036] Figure 12Fig. 1 is a schematic diagram of a current freewheeling circuit structure when the power switch of the power amplifier in the scheme of the present application has an open circuit fault, wherein (a) is a switch tube Q m4 Fig. 1 is a schematic diagram of a current freewheeling circuit structure when the power switch of the power amplifier in the scheme of the present application has an open circuit fault, wherein (a) is a switch tube Q m1 Fig. 1 is a schematic diagram of a current freewheeling circuit structure when the power switch of the power amplifier in the scheme of the present application has an open circuit fault, wherein (a) is a switch tube Q

[0037] Figure 13 Fig. 1 is a schematic diagram of a current freewheeling circuit structure when the power switch of the power amplifier in the scheme of the present application has an open circuit fault, wherein (a) is a switch tube Q

[0038] Figure 14 Fig. 1 is a schematic diagram of a current freewheeling circuit structure when the power switch of the power amplifier in the scheme of the present application has an open circuit fault, wherein (a) is a switch tube Q

[0039] In combination with the drawings, the reference signs in the embodiments of the present application are as follows:

[0040] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0042] In order to improve the reliability of the magnetic suspension motor control system, when the power amplifier fails, the fault needs to be diagnosed and isolated in the first time to avoid adverse effects on the magnetic suspension motor control system (such as the magnetic suspension bearing electromagnetic force will be out of control and the rotor cannot be stably suspended, and in serious cases, the protective bearing will be damaged, the rotor will be worn, etc.).

[0043] Among them, the failure of the power amplifier includes: open circuit fault of the power switch and current sensor failure. In some schemes, the fault diagnosis of the power amplifier is mostly concentrated on the power switch diagnosis of the inverter, and there are few fault diagnosis and fault tolerance schemes for the magnetic suspension bearing power amplifier. For example: some schemes mention a current sensor fault tolerance method, which needs to increase 2 additional current sensors and analog selection switches to form a current sensor redundancy structure, which greatly increases the hardware cost.

[0044] In order to solve the above problems, the scheme of the present application provides a control method of a power amplifier, specifically a fault diagnosis method applied to a switching power amplifier (such as a magnetic suspension bearing power amplifier).

[0045] According to embodiments of the present invention, a control method for a power amplifier is provided, such as... Figure 1 The diagram shows a flowchart of an embodiment of the method of the present invention. The power amplifier can be applied in a magnetic levitation motor control system, serving as a power amplifier for the electromagnetic bearing in the magnetic levitation motor control system, i.e., as an electromagnetic bearing power amplifier. The electromagnetic bearing power amplifier includes: n power amplifier modules, where n is a positive integer. The n power amplifier modules are arranged in parallel between the positive and negative terminals of the DC power supply on the input side of the electromagnetic bearing power amplifier. The electromagnetic bearing in the magnetic levitation motor control system has n bearing coils. One of the n power amplifier modules corresponds to one of the n bearing coils. Each of the n power amplifier modules can provide a control current to the corresponding bearing coil among the n bearing coils.

[0046] A bus current detection module (e.g., current sensor n+1) is installed between the positive terminal of the DC power supply and the n power amplifier modules. This bus current detection module is configured to detect the current in the main circuit of the electromagnetic bearing power amplifier, denoted as the bus current (e.g., current i). n+1 Between each of the power amplifier modules and the corresponding bearing coil of the electromagnetic bearing, a coil current detection module (such as any one of current sensors 1 to n) is provided. The coil current detection module is configured to detect the current of the corresponding bearing coil of the electromagnetic bearing, denoted as the coil current (e.g., the current i of coil m). m ).

[0047] The control method for the power amplifier includes steps S110 to S120.

[0048] In step S110, the bus current of the DC power supply is obtained, specifically, the current of the main circuit of the electromagnetic bearing power amplifier detected by the bus current detection module is obtained and denoted as the bus current of the DC power supply (e.g., current i). n+1 The coil current of each bearing coil in the electromagnetic bearing of the magnetic levitation motor control system is obtained. Specifically, the current of the corresponding bearing coil of the electromagnetic bearing detected by the coil current detection module at each bearing coil of the electromagnetic bearing is obtained and denoted as the coil current of each bearing coil of the electromagnetic bearing (e.g., the current i of coil m). m ).

[0049] In step S120, fault diagnosis is performed on the electromagnetic bearing power amplifier, the n coil current detection modules, and the bus current detection module based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing.

[0050] Figure 10 This is a schematic diagram of the power supply section of a magnetic levitation motor control system in a related scheme. (See diagram below.) Figure 10 As shown, the power supply section of the magnetic levitation motor control system includes: a DC power supply, a current sensor, a power amplifier, and other circuits. The positive terminal of the DC power supply is connected to the first terminal of the power amplifier, and the positive terminal of the DC power supply is also connected to the first terminal of the other circuits. The negative terminal of the DC power supply is connected to the second terminal of the power amplifier, and the negative terminal of the DC power supply is also connected to the second terminal of the other circuits. The current sensor is located on the connection line between the positive terminal of the DC power supply and the power amplifier.

[0051] exist Figure 10 In the example shown, the DC power supply may power other circuits besides the power amplifier, such as the bearing controller. To avoid interference from the DC power supply to other circuits, the present invention places the current sensor on the bus of the power amplifier.

[0052] The present invention provides a fault diagnosis scheme for switching power amplifiers. By utilizing the characteristics of bus current and coil current, and through the combination of software fault diagnosis and fault-tolerant algorithms, the fault diagnosis of the power amplifier can be realized. Specifically, it can diagnose single power switch open circuit faults and single current sensor faults, that is, it can diagnose current sensor faults and power switch open circuit faults in the power amplifier, which is beneficial to improving the reliability of the magnetic levitation motor control system.

[0053] In some embodiments, each of the power amplifier modules includes a power switching module and a freewheeling module. The power switching module includes a first switching transistor module and a second switching transistor module, the first switching transistor module being, for example, a switching transistor Q. n1 The second switching module, such as switching transistor Q, n4 The freewheeling module includes: a first diode module and a second diode module, wherein the first diode module is such as diode Q. n2 The second diode module, such as diode Q, n3 .

[0054] The positive terminal of the DC power supply, after passing through the bus current detection module, is connected to the first connection terminal (e.g., switch Q) of the first switching transistor module in each of the power amplifier modules. n1 The collector of the first diode module (such as diode Q), and the cathode of the first diode module (such as diode Q). n2 (cathode).

[0055] The negative terminal of the DC power supply is connected to the anode of the second diode module in each of the power amplifier modules (e.g., diode Q). n3The anode of the second switching transistor module and the second connection terminal of the second switching transistor module (such as the switching transistor Q). n4 (Emitter).

[0056] The second connection terminal (e.g., switch Q) of the first switching transistor module in each of the power amplifier modules n1 The emitter of the diode is connected to the cathode of the second diode module (such as diode Q). n3 The cathode). The anode of the first diode module in each of the power amplifier modules (such as diode Q). n2 The anode of the transistor is connected to the first connection terminal of the second switching transistor module (such as the switching transistor Q). n4 (collector).

[0057] The corresponding coil current detection module and the corresponding bearing coil of the electromagnetic bearing are set at the second connection terminal of the first switching transistor module in each power amplifier module (e.g., switching transistor Q). n1 The emitter of the diode and the anode of the first diode module (such as diode Q) n2 Between the anode and the cathode.

[0058] The faults of the electromagnetic bearing power amplifier include any of the following: a fault in either the first switching transistor module or the second switching transistor module, or a fault in either the bus current detection module or any of the n coil current detection modules.

[0059] Figure 11 This is a schematic diagram of the structure of one embodiment of the power amplifier in the present invention. Figure 11 As shown, the power amplifier includes: a DC power supply, n power amplifier modules, and a current sensor n+1. The positive terminal of the DC power supply is connected to the first terminal of the current sensor n+1. The second terminal of the current sensor n+1 is connected to the first terminal of each of the n power amplifier modules. The negative terminal of the DC power supply is connected to the second terminal of each of the n power amplifier modules. The n power amplifier modules include: the first power amplifier module to the nth power amplifier module, and each of the first to nth power amplifier modules has the same structure.

[0060] The first power amplifier module includes: a switching transistor Q. 11 Switching transistor Q 14 diode Q 12 diode Q 13 The current sensor is 1, and the coil is 1. The second terminal of the current sensor n+1 is connected to the switching transistor Q. 11 The collector of the current sensor n+1. The second terminal of the current sensor n+1 is also connected to the diode Q. 12 The cathode. Switch Q. 11 The base of the transistor is used as the control terminal. The switching transistor Q...11 The emitter of the diode is connected to diode Q after passing through current sensor 1 and coil 1. 12 The anode of the diode Q. 12 The anode is also connected to the switching transistor Q. 14 The collector of the switching transistor Q. 11 The emitter is also connected to diode Q. 13 The cathode of the diode Q. 13 The anode is connected to the switching transistor Q. 14 The emitter of the coil. Coil 1 can be equivalent to a series connection of resistor R1 and inductor L1. The current flowing through coil 1 is i1.

[0061] The nth power amplifier module includes: switching transistor Q n1 Switching transistor Q n4 diode Q n2 diode Q n3 A current sensor n and a coil n. The second terminal of the current sensor n+1 is connected to the switching transistor Q. n1 The collector of the current sensor n+1. The second terminal of the current sensor n+1 is also connected to the diode Q. n2 The cathode. Switch Q. n1 The base of the transistor is used as the control terminal. The switching transistor Q... n1 The emitter of the diode is connected to the diode Q after passing through the current sensor n and the coil n. n2 The anode of the diode Q. n2 The anode is also connected to the switching transistor Q. n4 The collector of the switching transistor Q. n1 The emitter is also connected to diode Q. n3 The cathode of the diode Q. n3 The anode is connected to the switching transistor Q. n4 The emitter. The coil n can be equivalent to a resistor R. n With inductor L n The series structure. The current flowing through coil n is i. n .

[0062] exist Figure 11 In the power amplifier shown, the number of magnetic levitation bearing coils is n (e.g., coil 1 to coil n). When a coil current is required (e.g., the current flowing through coil 1 is i1, and the current flowing through coil n is i...), the required current is... n When bidirectional flow occurs, diode Q n2 diode Q n3 Then it is related to the switching transistor Q n1 Switching transistor Q n4 The same controllable switch. When using two-level control, the switching transistor Q... n1 Switching transistor Q n4 Synchronous on or off, diode Q n2Diode Q n3 synchronously. When the switch tube Q n1 , the switch tube Q n4 is turned on, the coil current rises. The diode Q n1 , the diode Q n4 is turned off, the current flows through the diode, and the coil current drops.

[0063] In some solutions, a power amplifier is provided with 1 current sensor on each coil for measuring the current on the coil. For n coils, n current sensors are needed, n being a positive integer, which is costly. The solution of the present application is to additionally increase a current sensor n+1 on the bus (i.e. DC bus) of the power amplifier, and use the measurement value of the newly added current sensor n+1 to diagnose the current sensor failure of the power amplifier and the open circuit failure of the power switch, which is less costly.

[0064] In some embodiments, the fault diagnosis of the electromagnetic bearing power amplifier, n current detection modules of the coils, and the bus current detection module in step S120 according to the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing includes: the fault diagnosis of the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module according to the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing. Wherein, the current power amplifier module is one of the n power amplifier modules to be diagnosed. The current bearing coil of the electromagnetic bearing is one of the n bearing coils of the electromagnetic bearing corresponding to the current power amplifier module. Of course, the current coil current detection module is the coil current detection module at the current bearing coil of the electromagnetic bearing, such as current sensor m.

[0065] Wherein, the specific process of the fault diagnosis of the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module according to the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing, see the following exemplary description.

[0066] The following will be described in combination with Figure 2An embodiment flow diagram of the method of the present application for diagnosing faults of the switch tube module, the current coil current detection module, and the bus current detection module in the current power amplifier module according to the bus current and the current coil current of the current bearing coil is shown, which further illustrates the specific process of diagnosing faults of the switch tube module, the current coil current detection module, and the bus current detection module in the current power amplifier module according to the bus current and the current coil current of the current bearing coil, including steps S210 to S220.

[0067] In step S210, the variation value of the current coil current detected by the current coil current detection module in the set control period is determined, and the current difference value between the bus current and the n current coil currents detected by the n current coil detection modules is determined.

[0068] In some embodiments, the specific process of determining the variation value of the current coil current detected by the current coil current detection module in the set control period in step S210 can refer to the following exemplary description.

[0069] The specific process of determining the variation value of the current coil current detected by the current coil current detection module in the set control period in step S210 is described below in combination with Figure 3 An embodiment flow diagram of the method of the present application for determining the variation value of the current coil current detected by the current coil current detection module in the set control period is shown, which further illustrates the specific process of determining the variation value of the current coil current detected by the current coil current detection module in the set control period in step S210, including steps S310 and S320.

[0070] In step S310, the charging time variation rate and the discharging time variation rate of the current coil current detected by the current coil current detection module are determined.

[0071] In step S320, the product of the charging state duty cycle and the charging time variation rate and the sum of the product of the discharging state duty cycle and the discharging time variation rate are multiplied by the control period to determine the variation value of the current coil current detected by the current coil current detection module.

[0072] The open circuit fault of the power switch and the current sensor fault are common faults of the power amplifier, and both faults will cause the deviation of the current (i.e. the coil current) collected by the current sensor from the target current. The following takes coil m as an example for illustration, where m is a number between 1 and n. When the power amplifier is normally operated, the current I m of coil m is theoretically very close to the target current I m * i.e.:

[0073] |Im -I m * |≈0 (1)。

[0074] Some schemes, the formula (1) is met as the basis for diagnosis of whether the power amplifier failure. In fact, when the rotor suspension system in the magnetic levitation motor control system appears load fluctuation, in adjacent 2 control cycle, target current I m * Will appear larger changes, the power amplifier will appear current response speed is not enough, then only according to formula (1) for judgment will appear misdiagnosis.

[0075] The power amplifier will appear current response speed is not enough, specifically, because the current response speed and DC voltage size, load size related. Formula (2) can be seen when V dc And L, R is determined, the current rate of change is a fixed value, when the control required current rate of change exceeds the fixed value (such as the rotor is disturbed by large force), then the response speed is not enough.

[0076] In order to solve the problem of misdiagnosis only according to formula (1) for judgment, the scheme of the application, using power amplifier mathematical model as diagnostic tool. Charging moment, theoretically the current I m Of coil m with time t rate of change dI m / dt is:

[0077]

[0078] Among them, V dc Is the DC power supply voltage (i.e. DC bus voltage), R m Is the equivalent resistance of coil m resistance value, L m Is the equivalent inductance of coil m inductance value.

[0079] And discharge moment, the current I m Of coil m with time t rate of change dI m / dt is:

[0080]

[0081] Then, in a control cycle T coil m current I m (That is, the average current I m ) change value ΔI m , can be calculated by the following formula:

[0082]

[0083] Wherein, D is the power amplifier charging state duty cycle, 1-D is the power amplifier discharging state duty cycle, and is obtained by current closed-loop control.

[0084] In some embodiments, the specific process of determining the bus current and the current difference of the n coil currents detected by the n coil current detection modules in step S210 is described below.

[0085] The specific process of determining the bus current and the current difference of the n coil currents detected by the n coil current detection modules in step S210 is described below. Figure 4 An embodiment flowchart of determining the bus current and the current difference of the n coil currents detected by the n coil current detection modules in the method of the application is shown in the following figure, which further describes the specific process of determining the bus current and the current difference of the n coil currents detected by the n coil current detection modules in step S210, including steps S310 and S320.

[0086] In step S310, the sum of the n coil currents detected by the n coil current detection modules is determined. Wherein, the sum of the n coil currents detected by the n coil current detection modules is the first total current value or the second total current value.

[0087] In step S320, the difference between the bus current and the first total current value is determined as the first total current difference. The difference between the bus current and the second total current value is determined as the second total current difference. The first total current difference or the second total current difference is taken as the current difference between the bus current and the n coil currents detected by the n coil current detection modules.

[0088] Wherein, the first total current value refers to the sum of the product of the coil current detected by the first coil current detection module and the switch signal of the corresponding power amplifier module, and the product of the coil current detected by the n coil current detection module and the switch signal of the corresponding power amplifier module. Specifically, the process of determining the first total current value can be: determining the product of each coil current in the n coil currents detected by the n coil current detection modules and the switch signal of the corresponding power amplifier module, and determining the sum of the products of the n coil currents and the switch signals of the corresponding power amplifier modules as the difference between the sum of the n coil currents detected by the n coil current detection modules.

[0089] Alternatively, the second total current value refers to: the sum of the product of the coil current detected by the first coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the (m-1)th coil current detection module and the switching signal of the corresponding power amplifier module, the sum of the product of the coil current detected by the (m+1)th coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the nth coil current detection module and the switching signal of the corresponding power amplifier module, and the sum of the coil current detected by the mth coil current detection module. This sum is denoted as the second total current value. m is a positive integer from 1 to n. Specifically, the process of determining the second total current value can be as follows: First, determine the product of the m-1 coil currents detected by the first 1 to m-1 coil current detection modules among the n coil current detection modules and the switching signal of the corresponding power amplifier module. Then, determine the sum of the products of the m-1 coil currents detected by the first 1 to m-1 coil current detection modules and the switching signal of the corresponding power amplifier module as the sum of the m-1 coil currents detected by the m-1 coil current detection modules. Second, determine the product of the nm-1 coil currents detected by the last m+1 to n coil current detection modules among the n coil current detection modules and the switching signal of the corresponding power amplifier module. Then, determine the sum of the products of the nm-1 coil currents detected by the first m+1 to n coil current detection modules and the switching signal of the corresponding power amplifier module as the sum of the nm-1 coil currents detected by the nm-1 coil current detection modules. The sum of the m-1 coil currents detected by the m-1 coil current detection modules, the sum of the nm-1 coil currents detected by the nm-1 coil current detection modules, and the sum of the coil currents detected by the m-th coil current detection module are determined as the sum of the n coil currents detected by the n coil current detection modules.

[0090] Combined with the current I in coil m within a control cycle T m The change value ΔI m Under normal conditions, the current sampling value i of the current sensor m at time k is... m (k) and the current sampling value i of the current sensor m at time k-1. m The following relationship exists between (k-1):

[0091] i m (k)≈i m (k-1)+ΔI m (5). Therefore, when the power switch or current sensor m corresponding to coil m fails, we have:

[0092] |i m (k)-im (k-1)-ΔI m |>ε1 (6)。

[0093] Wherein, ε1 is the first error threshold, caused by control model deviation, software and hardware measurement error and other non-ideal conditions. Diagnose by formula (6) can avoid misdiagnosis caused by insufficient bandwidth when load fluctuates. In the scheme of the application, formula (6) can be used as a mathematical model of the power amplifier, that is, as a diagnostic tool. Wherein, the control model deviation refers to that when the magnetic levitation motor is running, the rotor fluctuates up and down on the suspension center, which will cause certain influence on the coil inductance L, resulting in certain deviation of the control model.

[0094] In the scheme of the application, after determining that any coil in the n coils corresponds to a faulty power switch or current sensor (such as power switch or current sensor m corresponding to coil m), the fault type needs to be identified. In the scheme of the application, a binary switch function S n :

[0095]

[0096] In three-level control, switch tube Q n1 , switch tube Q n4 does not need to be synchronously turned on or turned off, diode Q n2 , diode Q n4 does not need to be synchronously turned on or turned off, compared with two-level control, there is an additional state, that is, the current can flow through switch tube Q n1 diode Q n2 or switch tube Q n4 diode Q n3 for freewheeling. When the power amplifier is running normally, the bus current i n+1 of the power amplifier under two-level control and the coil current i n have the following relationship:

[0097]

[0098]

[0099] Wherein, in formula (8), y is a number between 1 and n, i y is the current of coil y detected by current sensor y, S y is the switching signal of the power switch in the power amplifier.

[0100] In formula (9), x is a number between 1 and n, i x is the current of coil x detected by current sensor x, S x is the switching signal of the power switch in the power amplifier.

[0101] Figure 12 This is a schematic diagram of the current freewheeling circuit in the power amplifier under open-circuit fault of the power switch in the present invention, wherein (a) is the switching transistor Q. m4 A schematic diagram of the current freewheeling circuit under open-circuit fault conditions is shown in (b), where the switching transistor Q is located. m1 A schematic diagram of the freewheeling circuit during an open-circuit fault. Assume the switching transistor Q... m1 or switching transistor Q m4 An open circuit fault prevents the power amplifier from achieving its charging state, such as... Figure 12 As shown, current flows through diode Q. m2 or diode Q m3 The freewheeling current does not affect the discharge state of the power amplifier, and the current i detected by the current sensor m of coil m is... m This is the actual current in coil m, and the bus current i is at this time. n+1 With coil current i m The equation (9) is satisfied. If the fault occurs in current sensor m, the current i detected by current sensor m will be... m If the current deviates from the actual current of the coil, then formula (9) is not valid.

[0102] Step S220: Based on the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module. Here, the current coil current is the coil current of the current bearing coil detected by the current coil current detection module at the current detection time. The previous coil current is the coil current of the current bearing coil detected by the current coil current detection module at the previous detection time. The current detection time and the previous detection time are two adjacent detection times within the set detection time.

[0103] This invention provides a fault diagnosis scheme for power switches and current sensors in a two-level power amplifier. It utilizes the characteristics of bus current and coil current to diagnose current sensor faults and power switch open-circuit faults in the power amplifier. Furthermore, in the case of a single current sensor failure, a fault-tolerant current is used to replace the faulty sensor's detection current, achieving fault-tolerant operation under single current sensor failure and improving the stability of the magnetic levitation motor control system. Thus, by implementing fault diagnosis for the power amplifier's power switch or a single current sensor, it solves the problem of the magnetic levitation bearing system in the magnetic levitation motor control system failing to operate normally when a current sensor in the power amplifier fails, further enhancing the reliability and stability of the magnetic levitation motor control system.

[0104] In some embodiments, the specific process of fault diagnosis in step S220, which involves using the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules, to diagnose the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module, can be found in the following exemplary description.

[0105] The following is combined Figure 5 The illustrated flowchart illustrates an embodiment of the method of the present invention for fault diagnosis of the switching transistor module, the current coil current detection module at the current bearing coil, and the bus current detection module in the current power amplifier module based on the current coil current, the previous coil current, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the currents of n coils. Further, it explains the specific process of fault diagnosis of the switching transistor module, the current coil current detection module at the current bearing coil, and the bus current detection module in the current power amplifier module based on the current coil current, the previous coil current, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the currents of n coils in step S220, including steps S510 to S540.

[0106] Step S510: Determine the absolute value of the difference between the current coil current detected by the current coil current detection module, the previous coil current detected by the current coil current detection module, and the change value of the coil current detected by the current coil current detection module, and record it as the first current difference value.

[0107] Step S520: Determine whether the first current difference is greater than the set first error threshold.

[0108] Figure 13 Figure 1 is a flow chart of a fault diagnosis process of an embodiment of the fault diagnosis device for a switched power amplifier (such as a magnetic bearing power amplifier) in the scheme of the present application. As shown in Figure 1, the fault diagnosis process of the fault diagnosis device for a switched power amplifier (such as a magnetic bearing power amplifier) includes the following steps: Figure 13

[0109] Step 1, the MCU acquires the current signal, duty cycle signal, switching signal, and error threshold value required for diagnosis.

[0110] The current signal required for diagnosis includes: the current sampling value i m (k) of the current sensor m of the coil m at time k, the current sampling value i m (k-1) of the current sensor m of the coil m at time k-1, the change value ΔI m of the current I m of the coil m in a control period T, the current i m detected by the current sensor m, the bus current i n+1 of the power amplifier, and the coil current i n .

[0111] The duty cycle signal required for diagnosis includes: D is the duty cycle of the charging state of the power amplifier, and 1-D is the duty cycle of the discharging state of the power amplifier.

[0112] The switching signal required for diagnosis includes: when the switch tube Q n1 and the switch tube Q n4 are turned on at the same time, the switching signal S n =1. The switching signal required for diagnosis also includes: when the diode Q n2 and the diode Q n3 are turned on at the same time, the switching signal S n =-1.

[0113] The error threshold value required for diagnosis includes: the first error threshold value ε1 and the second error threshold value ε2.

[0114] Step 2, according to the current sampling value i m (k) of the current sensor m of the coil m at time k, the current sampling value i m (k-1) of the current sensor m of the coil m at time k-1, the change value ΔI m of the current I m of the coil m in a control period T, and the first error threshold value ε1, it is determined whether the following formula (6) is satisfied:

[0115] |i m (k)-i m ​(k-1)-ΔI m |>ε1 (6)。

[0116] If yes, step 3 is performed. Otherwise, step 4 is performed.

[0117] In step S530, if the first current difference value is greater than the first error threshold value, it is determined that the switch tube module in the current power amplifier module is faulty or the current coil current detection module is faulty, and the fault type is determined according to the bus current and the second total current difference value.

[0118] In some embodiments, the specific process of determining the fault type according to the bus current and the second total current difference value in step S530 is described in the following example.

[0119] The following Figure 6 The following

[0120] In step S610, the absolute value of the difference between the bus current and the second total current difference value is determined, denoted as a second current difference value.

[0121] In step S620, it is determined whether the second current difference value is less than or equal to a set second error threshold value.

[0122] In step S630, if the second current difference value is less than or equal to the second error threshold value, it is determined that the switch tube module in the current power amplifier module is faulty and the current coil current detection module is not faulty.

[0123] In step S640, if the second current difference value is greater than the second error threshold value, it is determined that the current coil current detection module is faulty and the switch tube module in the current power amplifier module is not faulty.

[0124] As Figure 13 As shown in the fault diagnosis process of the fault diagnosis device applied to the switch power amplifier (such as the magnetic levitation bearing power amplifier), the fault diagnosis process further includes:

[0125] In step 3, according to the current i m , the power amplifier bus current i n+1 , each coil current i n , the switch signal, and the second error threshold value ε2, it is determined whether the following formula (11) is satisfied:

[0126]

[0127] If yes, it is determined that the switch tube Q m1 or the switch tube Q m4 is faulty. Otherwise, it is determined that the current sensor m is faulty.

[0128] In step S540, if the first current difference value is less than or equal to the first error threshold value, it is determined that the switch tube module in the current power amplifier module and the current coil current detection module are both not faulty, and whether the bus current detection module is faulty is determined according to the bus current and the first total current difference value.

[0129] In some embodiments, the specific process of determining whether the bus current detection module is faulty according to the bus current and the first total current difference value in step S540 is described in the following example.

[0130] The following will be described in combination with Figure 7 an embodiment flowchart of determining whether the bus current detection module is faulty according to the bus current and the first total current difference value in the method of the application shown in FIG. 7, which further describes the specific process of determining whether the bus current detection module is faulty according to the bus current and the first total current difference value in step S540, including steps S710 to S740.

[0131] In step S710, the absolute value of the difference value of the bus current and the first total current difference value is determined, denoted as a third current difference value.

[0132] In step S720, it is determined whether the third current difference value is less than or equal to a set second error threshold value.

[0133] In step S730, if the third current difference value is less than or equal to the second error threshold value, it is determined that the switch tube module in the current power amplifier module, the current coil current detection module, and the bus current detection module are all not faulty.

[0134] In step S740, if the third current difference value is greater than the second error threshold value, it is determined that the bus current detection module is faulty.

[0135] As Figure 13 shown in FIG. 8, the fault diagnosis process of the fault diagnosis device applied to the switch power amplifier (such as the magnetic levitation bearing power amplifier) further includes:

[0136] In step 4, whether the following formula (12) is satisfied is determined according to the power amplifier bus current i n+1 , each coil current i n , the switch signal, and the second error threshold value ε2:

[0137]

[0138] If so, then the power amplifier is faulty due to a lack of power switches and a faulty current sensor. Otherwise, the current sensor n+1 is faulty.

[0139] Figure 14 This is a current characteristic table for a power amplifier under different fault conditions. In the scheme of this invention, the current characteristic tables under different fault conditions are obtained as follows: Figure 14 As shown, ε2 is the second error threshold. It can be seen that different fault states have different current characteristics. The solution of this invention can simultaneously diagnose power switch open circuit faults and current sensor faults. The second error threshold ε2 can be selected based on the measurement error.

[0140] In some implementations, the method further includes: controlling the electromagnetic bearing power amplifier to operate in a fault-tolerant manner in the event that any one of the n coil current detection modules fails.

[0141] The following is combined Figure 8 The flowchart shown is a schematic diagram of an embodiment of the method of the present invention for controlling the electromagnetic bearing power amplifier to operate in a fault-tolerant manner in the event of a failure of any coil current detection module. The specific process of controlling the electromagnetic bearing power amplifier to operate in a fault-tolerant manner in the event of a failure of any coil current detection module is further explained, including steps S810 to S830.

[0142] Step S810: After performing fault diagnosis on the electromagnetic bearing power amplifier, the n coil current detection modules, and the bus current detection module based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing, if any of the n coil current detection modules fails, the sum of the products of the coil current detected by the remaining coil current detection modules and the corresponding power amplifier module's switching signal is determined and recorded as the third total current value.

[0143] Step S820: The difference between the bus current and the third total current value is determined as the fault-tolerant current of the current detection module of any coil under fault conditions.

[0144] Step S830: Control the bearing coil corresponding to any coil current detection module to work according to the fault-tolerant current.

[0145] Combination Figure 13 In the example shown, if the fault is finally diagnosed to occur in the current sensor m, then according to formula (9), the fault-tolerant current value i' m The current i detected by the current sensor m is replaced by the current i mThis allows for fault-tolerant operation even under a single sensor failure. Therefore, the fault-tolerant current i' of the current sensor m under fault conditions... m Represented as:

[0146]

[0147] The solution of the present invention can diagnose single power switch open circuit faults and single current sensor faults through formulas (6) and (10), and can achieve fault-tolerant operation under single current sensor faults.

[0148] The present invention proposes a fault diagnosis device for switching power amplifiers (such as electromagnetic bearing power amplifiers), and provides a power amplifier fault diagnosis and fault tolerance scheme. By adding a current sensor to the bus of the power amplifier, the relationship between the coil current and the target current, and between the coil current and the bus current, is used to diagnose and tolerate the power amplifier. This achieves fault tolerance control when a single current sensor is used, and can diagnose open circuit faults in the power switch and current sensor faults. It achieves fault tolerance for a single current sensor, solves the problem that the magnetic levitation motor control system cannot operate when a single current sensor fails, and improves the reliability of the magnetic levitation motor control system.

[0149] In this invention, a current detection method suitable for two-level power amplifiers is used. Leveraging the no-follow-current characteristic of two-level control, only one current sensor needs to be added. Through software fault diagnosis and fault-tolerant algorithms, the characteristics of bus current and coil current can be used to diagnose single power switch open-circuit faults and single current sensor faults. Furthermore, in the event of a single current sensor fault, the fault-tolerant current replaces the faulty sensor's detection current, enabling fault-tolerant operation under single current sensor faults and improving the reliability of the magnetic levitation motor control system. Specifically, this invention only adds an additional current sensor n+1 to the power amplifier bus (i.e., the DC bus). The measurement value of the newly added current sensor n+1 is used to diagnose power amplifier current sensor faults and power switch open-circuit faults, and to achieve fault-tolerant control under single current sensor faults, resulting in lower costs.

[0150] According to the technical scheme of the embodiment, the bus current of the power amplifier is detected through the current sensor arranged on the bus of the power amplifier. The coil current of each coil of the power amplifier is detected through the current sensor arranged at each coil of the power amplifier. Then, the fault diagnosis of the current sensor and the open circuit fault of the power switch in the power amplifier is realized according to the relationship between the coil current and the target current and the relationship between the coil current and the bus current, so that the fault condition of the power amplifier can be determined in time. Therefore, the fault diagnosis of the power amplifier is realized according to the bus current and the coil current, the fault condition of the power amplifier can be determined in time, the reliability of the magnetic levitation motor control system is not affected due to the failure of the power amplifier which is not found in time, and the reliability of the magnetic levitation motor control system is improved.

[0151] According to the embodiment of the present application, a control device of a power amplifier corresponding to the control method of the power amplifier is also provided. Referring to Figure 9 The power amplifier can be applied to a magnetic levitation motor control system as a power amplifier of an electromagnetic bearing in the magnetic levitation motor control system, that is, as an electromagnetic bearing power amplifier. The electromagnetic bearing power amplifier comprises n power amplifier modules, where n is a positive integer. The n power amplifier modules are arranged in parallel between the positive and negative poles of a direct current power supply on the input side of the electromagnetic bearing power amplifier. The electromagnetic bearing in the magnetic levitation motor control system has n bearing coils. One of the n power amplifier modules corresponds to one of the n bearing coils. Each of the n power amplifier modules can provide a control current for the corresponding bearing coil among the n bearing coils.

[0152] A bus current detection module (such as current sensor n+1) is arranged between the positive pole of the direct current power supply and the n power amplifier modules. The bus current detection module is configured to detect the current of the main circuit of the electromagnetic bearing power amplifier, denoted as bus current (such as current i n+1 A coil current detection module (such as any one of current sensor 1 to current sensor n) is arranged between each power amplifier module and the corresponding bearing coil of the electromagnetic bearing. The coil current detection module is configured to detect the current of the corresponding bearing coil of the electromagnetic bearing, denoted as coil current (such as the current i m of coil m).

[0153] The control device of the power amplifier comprises an acquisition unit 102 and a control unit 104.

[0154] The acquisition unit 102 is configured to acquire the bus current of the DC power supply, specifically, to acquire the current of the main circuit of the electromagnetic bearing power amplifier detected by the bus current detection module, denoted as the bus current of the DC power supply (e.g., current i). n+1 The coil current of each bearing coil in the electromagnetic bearing of the magnetic levitation motor control system is obtained. Specifically, the current of the corresponding bearing coil of the electromagnetic bearing detected by the coil current detection module at each bearing coil of the electromagnetic bearing is obtained and denoted as the coil current of each bearing coil of the electromagnetic bearing (e.g., the current i of coil m). m For the specific functions and processing of the acquisition unit 102, please refer to step S110.

[0155] Control unit 104 is configured to perform fault diagnosis on the electromagnetic bearing power amplifier, n coil current detection modules, and the bus current detection module based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing. The specific functions and processing of this control unit 104 are described in step S120.

[0156] Figure 10 This is a schematic diagram of the power supply section of a magnetic levitation motor control system in a related scheme. (See diagram below.) Figure 10 As shown, the power supply section of the magnetic levitation motor control system includes: a DC power supply, a current sensor, a power amplifier, and other circuits. The positive terminal of the DC power supply is connected to the first terminal of the power amplifier, and the positive terminal of the DC power supply is also connected to the first terminal of the other circuits. The negative terminal of the DC power supply is connected to the second terminal of the power amplifier, and the negative terminal of the DC power supply is also connected to the second terminal of the other circuits. The current sensor is located on the connection line between the positive terminal of the DC power supply and the power amplifier.

[0157] exist Figure 10 In the example shown, the DC power supply may power other circuits besides the power amplifier, such as the bearing controller. To avoid interference from the DC power supply to other circuits, the present invention places the current sensor on the bus of the power amplifier.

[0158] The present invention provides a fault diagnosis scheme for switching power amplifiers. By utilizing the characteristics of bus current and coil current, and through the combination of software fault diagnosis and fault-tolerant algorithms, the fault diagnosis of the power amplifier can be realized. Specifically, it can diagnose single power switch open circuit faults and single current sensor faults, that is, it can diagnose current sensor faults and power switch open circuit faults in the power amplifier, which is beneficial to improving the reliability of the magnetic levitation motor control system.

[0159] In some embodiments, each of the power amplifier modules comprises a power switch module and a freewheeling module. The power switch module comprises a first switch tube module and a second switch tube module, the first switch tube module being, for example, switch tube Q n1 , and the second switch tube module being, for example, switch tube Q n4 . The freewheeling module comprises a first diode module and a second diode module, the first diode module being, for example, diode Q n2 , and the second diode module being, for example, diode Q n3 .

[0160] The positive pole of the direct current power supply is connected to the first connection end (for example, the collector of switch tube Q n1 ) of the first switch tube module and the cathode (for example, the cathode of diode Q n2 ) of the first diode module in each of the power amplifier modules via the bus current detection module.

[0161] The negative pole of the direct current power supply is connected to the anode (for example, the anode of diode Q n3 ) of the second diode module and the second connection end (for example, the emitter of switch tube Q n4 ) of the second switch tube module in each of the power amplifier modules.

[0162] The second connection end (for example, the emitter of switch tube Q n1 ) of the first switch tube module is connected to the cathode (for example, the cathode of diode Q n3 ) of the second diode module in each of the power amplifier modules. The anode (for example, the anode of diode Q n2 ) of the first diode module is connected to the first connection end (for example, the collector of switch tube Q n4 ) of the second switch tube module in each of the power amplifier modules.

[0163] The corresponding coil current detection module and the corresponding bearing coil of the electromagnetic bearing are arranged between the second connection end (for example, the emitter of switch tube Q n1 ) of the first switch tube module and the anode (for example, the anode of diode Q n2 ) of the first diode module in each of the power amplifier modules.

[0164] The failure of the electromagnetic bearing power amplifier comprises any of the following failures: the failure of any of the first switch tube module and the second switch tube module, the failure of any of the bus current detection module and the n coil current detection modules.

[0165] Figure 11 Figure 1 is a structural schematic diagram of an embodiment of the power amplifier in the scheme of the present application. As shown in Figure 1, the electromagnetic bearing power amplifier comprises a direct current power supply, a bus current detection module, n power amplifier modules, and n coil current detection modules. Figure 11As shown, the power amplifier includes: a DC power supply, n power amplifier modules, and a current sensor n+1. The positive terminal of the DC power supply is connected to the first terminal of the current sensor n+1. The second terminal of the current sensor n+1 is connected to the first terminal of each of the n power amplifier modules. The negative terminal of the DC power supply is connected to the second terminal of each of the n power amplifier modules. The n power amplifier modules include: the first power amplifier module to the nth power amplifier module, and each of the first to nth power amplifier modules has the same structure.

[0166] The first power amplifier module includes: a switching transistor Q. 11 Switching transistor Q 14 diode Q 12 diode Q 13 The current sensor is 1, and the coil is 1. The second terminal of the current sensor n+1 is connected to the switching transistor Q. 11 The collector of the current sensor n+1. The second terminal of the current sensor n+1 is also connected to the diode Q. 12 The cathode. Switch Q. 11 The base of the transistor is used as the control terminal. The switching transistor Q... 11 The emitter of the diode is connected to diode Q after passing through current sensor 1 and coil 1. 12 The anode of the diode Q. 12 The anode is also connected to the switching transistor Q. 14 The collector of the switching transistor Q. 11 The emitter is also connected to diode Q. 13 The cathode of the diode Q. 13 The anode is connected to the switching transistor Q. 14 The emitter of the coil. Coil 1 can be equivalent to a series connection of resistor R1 and inductor L1. The current flowing through coil 1 is i1.

[0167] The nth power amplifier module includes: switching transistor Q n1 Switching transistor Q n4 diode Q n2 diode Q n3 A current sensor n and a coil n. The second terminal of the current sensor n+1 is connected to the switching transistor Q. n1 The collector of the current sensor n+1. The second terminal of the current sensor n+1 is also connected to the diode Q. n2 The cathode. Switch Q. n1 The base of the transistor is used as the control terminal. The switching transistor Q... n1 The emitter of the diode is connected to the diode Q after passing through the current sensor n and the coil n. n2 The anode of the diode Q. n2 The anode is also connected to the switching transistor Q. n4 The collector of the switching transistor Q. n1The emitter is also connected to diode Q. n3 The cathode of the diode Q. n3 The anode is connected to the switching transistor Q. n4 The emitter. The coil n can be equivalent to a resistor R. n With inductor L n The series structure. The current flowing through coil n is i. n .

[0168] exist Figure 11 In the power amplifier shown, the number of magnetic levitation bearing coils is n (e.g., coil 1 to coil n). When a coil current is required (e.g., the current flowing through coil 1 is i1, and the current flowing through coil n is i...), the required current is... n When bidirectional flow occurs, diode Q n2 diode Q n3 Then it is related to the switching transistor Q n1 Switching transistor Q n4 The same controllable switch. When using two-level control, the switching transistor Q... n1 Switching transistor Q n4 Synchronous on or off, diode Q n2 diode Q n3 Synchronous turn-on or turn-off. When the switching transistor Q... n1 Switching transistor Q n4 When the diode is turned on, the coil current increases. Diode Q n1 diode Q n4 When turned off, current freewheels through the diode, and the coil current decreases.

[0169] In some solutions, the power amplifier uses one current sensor on each coil to measure the current in that coil. For n coils, n current sensors are needed, where n is a positive integer, which is costly. The solution of this invention adds an additional current sensor n+1 to the power amplifier's bus (i.e., the DC bus). The measurement value of the newly added current sensor n+1 is used to diagnose current sensor faults and power switch open-circuit faults in the power amplifier, resulting in lower cost.

[0170] In some embodiments, the control unit 104 performs fault diagnosis on the electromagnetic bearing power amplifier, the n coil current detection modules, and the bus current detection module based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing, including:

[0171] The control unit 104 is further configured to perform fault diagnosis on the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module according to the bus current of the direct current power supply and the coil current of the current bearing coil of the electromagnetic bearing. The current power amplifier module is one of the n power amplifier modules to be diagnosed. The current bearing coil of the electromagnetic bearing is one of the n bearing coils of the electromagnetic bearing corresponding to the current power amplifier module. Of course, the current coil current detection module is a coil current detection module such as current sensor m at the current bearing coil of the electromagnetic bearing.

[0172] The control unit 104 performs fault diagnosis on the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module according to the bus current of the direct current power supply and the coil current of the current bearing coil of the electromagnetic bearing, including:

[0173] The control unit 104 is further configured to determine the change value of the coil current detected by the current coil current detection module within a set control period, and determine the current difference value of the bus current and the n coil currents detected by the n coil current detection modules. For specific functions and processes of the control unit 104, see step S210.

[0174] In some embodiments, the control unit 104 determines the change value of the coil current detected by the current coil current detection module within a set control period, including:

[0175] The control unit 104 is further configured to determine the charging time variation rate and the discharging time variation rate of the coil current detected by the current coil current detection module. For specific functions and processes of the control unit 104, see step S310.

[0176] The control unit 104 is further configured to combine the charging state duty cycle and the discharging state duty cycle of the electromagnetic bearing power amplifier, and the set control period, multiply the product of the charging state duty cycle and the charging time variation rate, and the product of the discharging state duty cycle and the discharging time variation rate, and the value obtained by multiplying the control period, to determine the change value of the coil current detected by the current coil current detection module. For specific functions and processes of the control unit 104, see step S320.

[0177] The open circuit fault of the power switch and the current sensor fault are common faults of the power amplifier, and both faults will cause the current (i.e. coil current) collected by the current sensor to deviate from the target current. Taking coil m as an example, m is a number between 1 and n. When the power amplifier is normally operated, the current I m of coil m theoretically changes with time t as follows: m * The difference is small, that is:

[0178] |I m -I m * |≈0 (1).

[0179] In some schemes, whether formula (1) is satisfied is taken as the basis for diagnosing whether the power amplifier has a fault. In fact, when the rotor suspension system in the magnetic levitation motor control system has load fluctuation, the target current I m * will change greatly in the adjacent two control periods, and the power amplifier will have a current response speed that is not enough, so that the diagnosis will be misdiagnosed only according to formula (1).

[0180] In order to solve the problem that the diagnosis will be misdiagnosed only according to formula (1), the scheme of the present application uses the mathematical model of the power amplifier as a diagnostic tool. At the charging moment, the current I m of coil m theoretically changes with time t at a rate dI m / dt as follows:

[0181]

[0182] Wherein, V dc is the DC power supply voltage (i.e. DC bus voltage), R m is the resistance value of the equivalent resistance of coil m, and L m is the inductance value of the equivalent inductance of coil m.

[0183] And at the discharging moment, the current I m of coil m changes with time t at a rate dI m / dt as follows:

[0184]

[0185] Then, the change value ΔI m of the current I m of coil m in a control period T can be calculated by the following formula:

[0186]

[0187] Wherein, D is the power amplifier charging state duty cycle, 1-D is the power amplifier discharging state duty cycle, and the current closed loop control is obtained.

[0188] In some embodiments, the control unit 104 determines the current difference between the bus current and the n coil currents detected by the n coil current detection modules, including:

[0189] The control unit 104 is specifically further configured to determine the sum of the n coil currents detected by the n coil current detection modules. Wherein, the sum of the n coil currents detected by the n coil current detection modules is the first total current value or the second total current value. For specific functions and processes of the control unit 104, see step S410.

[0190] The control unit 104 is specifically further configured to determine the difference between the bus current and the first total current value as the first total current difference. The difference between the bus current and the second total current value is determined as the second total current difference. And the first total current difference or the second total current difference is taken as the current difference between the bus current and the n coil currents detected by the n coil current detection modules. For specific functions and processes of the control unit 104, see step S420.

[0191] Wherein, the first total current value refers to the sum of the product of the coil current detected by the first coil current detection module and the switch signal of the corresponding power amplifier module, and the product of the coil current detected by the n coil current detection module and the switch signal of the corresponding power amplifier module. Specifically, the process of determining the first total current value can be: determining the product of each coil current in the n coil currents detected by the n coil current detection modules and the switch signal of the corresponding power amplifier module, and the sum of the products of the n coil currents and the switch signal of the corresponding power amplifier module is determined as the difference between the sum of the n coil currents detected by the n coil current detection modules.

[0192] Alternatively, the second total current value refers to: the sum of the product of the coil current detected by the first coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the (m-1)th coil current detection module and the switching signal of the corresponding power amplifier module, the sum of the product of the coil current detected by the (m+1)th coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the nth coil current detection module and the switching signal of the corresponding power amplifier module, and the sum of the coil current detected by the mth coil current detection module. This sum is denoted as the second total current value. m is a positive integer from 1 to n. Specifically, the process of determining the second total current value can be as follows: First, determine the product of the m-1 coil currents detected by the first 1 to m-1 coil current detection modules among the n coil current detection modules and the switching signal of the corresponding power amplifier module. Then, determine the sum of the products of the m-1 coil currents detected by the first 1 to m-1 coil current detection modules and the switching signal of the corresponding power amplifier module as the sum of the m-1 coil currents detected by the m-1 coil current detection modules. Second, determine the product of the nm-1 coil currents detected by the last m+1 to n coil current detection modules among the n coil current detection modules and the switching signal of the corresponding power amplifier module. Then, determine the sum of the products of the nm-1 coil currents detected by the first m+1 to n coil current detection modules and the switching signal of the corresponding power amplifier module as the sum of the nm-1 coil currents detected by the nm-1 coil current detection modules. The sum of the m-1 coil currents detected by the m-1 coil current detection modules, the sum of the nm-1 coil currents detected by the nm-1 coil current detection modules, and the sum of the coil currents detected by the m-th coil current detection module are determined as the sum of the n coil currents detected by the n coil current detection modules.

[0193] Combined with the current I in coil m within a control cycle T m The change value ΔI m Under normal conditions, the current sampling value i of the current sensor m at time k is... m (k) and the current sampling value i of the current sensor m at time k-1. m The following relationship exists between (k-1):

[0194] i m (k)≈i m (k-1)+ΔI m (5). Therefore, when the power switch or current sensor m corresponding to coil m fails, we have:

[0195] |i m (k)-im (k-1)-ΔI m |>ε1 (6)。

[0196] wherein, ε1 is the first error threshold, caused by control model deviation, software and hardware measurement error and other non-ideal conditions. Diagnosis is carried out by using formula (6), which can avoid misdiagnosis caused by insufficient bandwidth when the load fluctuates. In the scheme of the present application, formula (6) can be used as a mathematical model of the power amplifier, that is, as a diagnostic tool.

[0197] In the scheme of the present application, after determining that any coil in the n coils has a fault in the corresponding power switch or current sensor (such as the power switch or current sensor m corresponding to the coil m), it is also necessary to identify the fault type. In the scheme of the present application, a binary switch function S n :

[0198]

[0199] When the power amplifier is running normally, the bus current i n+1 of the power amplifier under two-level control and the coil current i n have the following relationship:

[0200]

[0201]

[0202] wherein, in formula (8), y is a number between 1 and n, i y is the current of coil y detected by current sensor y, S y is the switching signal of the power switch in the power amplifier.

[0203] In formula (9), x is a number between 1 and n, i x is the current of coil x detected by current sensor x, S x is the switching signal of the power switch in the power amplifier.

[0204] Figure 12 is a schematic structural diagram of the current freewheeling circuit when the power switch of the power amplifier in the scheme of the present application has an open circuit fault, wherein (a) is the switching tube Q m4 is a schematic structural diagram of the current freewheeling circuit when the power switch has an open circuit fault, (b) is the switching tube Q m1 is a schematic structural diagram of the current freewheeling circuit when the power switch has an open circuit fault. It is assumed that the switching tube Q m1 or the switching tube Q m4 has an open circuit fault, and the charging state of the power amplifier cannot be achieved, as shown in Figure 12 , the current passes through the diode Q m2 or the diode Qm3 The freewheeling current does not affect the discharge state of the power amplifier, and the current i detected by the current sensor m of coil m is... m This is the actual current in coil m, and the bus current i is at this time. n+1 With coil current i m The equation (9) is satisfied. If the fault occurs in current sensor m, the current i detected by current sensor m will be... m If the current deviates from the actual current of the coil, then formula (9) is not valid.

[0205] The control unit 104 is further configured to perform fault diagnosis on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module based on the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules. Here, the current coil current is the coil current of the current bearing coil detected by the current coil current detection module at the current detection time. The previous coil current is the coil current of the current bearing coil detected by the current coil current detection module at the previous detection time. The current detection time and the previous detection time are two adjacent detection times in the set detection time. For the specific functions and processing of this control unit 104, please refer to step S220.

[0206] This invention provides a fault diagnosis scheme for power switches and current sensors in a two-level power amplifier. It utilizes the characteristics of bus current and coil current to diagnose current sensor faults and power switch open-circuit faults in the power amplifier. Furthermore, in the case of a single current sensor failure, a fault-tolerant current is used to replace the faulty sensor's detection current, achieving fault-tolerant operation under single current sensor failure and improving the stability of the magnetic levitation motor control system. Thus, by implementing fault diagnosis for the power amplifier's power switch or a single current sensor, it solves the problem of the magnetic levitation bearing system in the magnetic levitation motor control system failing to operate normally when a current sensor in the power amplifier fails, further enhancing the reliability and stability of the magnetic levitation motor control system.

[0207] In some embodiments, the control unit 104 performs fault diagnosis on the switch tube module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module according to the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference value between the bus current and the n coil currents detected by the n coil current detection modules, including:

[0208] The control unit 104 is specifically further configured to determine the absolute value of the difference between the current coil current detected by the current coil current detection module and the previous coil current detected by the current coil current detection module and the change value of the coil current detected by the current coil current detection module, denoted as a first current difference value. For specific functions and processes of the control unit 104, see step S510.

[0209] The control unit 104 is specifically further configured to determine whether the first current difference value is greater than a set first error threshold. For specific functions and processes of the control unit 104, see step S520.

[0210] Figure 13 For the fault diagnosis flowchart of an embodiment of the fault diagnosis device for a switching power amplifier (such as a magnetic levitation bearing power amplifier) in the scheme of the present application. As shown in Figure 13 The fault diagnosis flowchart of the fault diagnosis device for a switching power amplifier (such as a magnetic levitation bearing power amplifier) includes:

[0211] Step 1, the MCU obtains current signals, duty cycle signals, switch signals, and error thresholds required for diagnosis, etc.

[0212] Among them, the current signals required for diagnosis include: the current sampling value i m (k) of the current sensor m of the coil m at time k, the current sampling value i m (k-1) of the current sensor m of the coil m at time k-1, the change value ΔI m of the current I m on the coil m in a control period T, the current i m detected by the current sensor m, the bus current i n+1 of the power amplifier, and the coil current i n .

[0213] The duty cycle signals required for diagnosis include: D is the duty cycle of the charging state of the power amplifier, and 1-D is the duty cycle of the discharging state of the power amplifier.

[0214] The switch signal required for diagnosis includes: switch tube Q n1 and switch tube Q n4 When turned on at the same time, the switch signal S n =1. The switch signal required for diagnosis also includes: diode Q n2 and diode Q n3 When turned on at the same time, the switch signal S n =-1.

[0215] The error threshold required for diagnosis includes: first error threshold ε1, second error threshold ε2.

[0216] Step 2, according to the current sampling value i m (k) of the current sensor m of the coil m at time k, the current sampling value i m (k-1) of the current sensor m of the coil m at time k-1, the change value ΔI m of the current I m of the coil m in a control period T, and the first error threshold ε1, determine whether it satisfies the following formula (6):

[0217] |i m (k)-i m (k-1)-ΔI m |>ε1 (6).

[0218] If yes, step 3 is executed. Otherwise, step 4 is executed.

[0219] The control unit 104 is specifically further configured to determine that the switch tube module in the current power amplifier module fails or the current coil current detection module fails if the first current difference value is greater than the first error threshold, and determine the fault type according to the bus current and the second total current difference value. For specific functions and processing of the control unit 104, see step S530.

[0220] In some embodiments, the control unit 104 determines the fault type according to the bus current and the second total current difference value, including:

[0221] The control unit 104 is specifically further configured to determine the absolute value of the difference between the bus current and the second total current difference value, denoted as the second current difference value. For specific functions and processing of the control unit 104, see step S610.

[0222] The control unit 104 is specifically further configured to determine whether the second current difference value is less than or equal to a set second error threshold. For specific functions and processing of the control unit 104, see step S620.

[0223] The control unit 104 is further configured to determine that the switching transistor module in the current power amplifier module is faulty and the current coil current detection module is not faulty if the second current difference is less than or equal to the second error threshold. The specific functions and processing of this control unit 104 are described in step S630.

[0224] The control unit 104 is further configured to determine that the current coil current detection module is faulty and the switching transistor module in the current power amplifier module is not faulty if the second current difference is greater than the second error threshold. The specific functions and processing of this control unit 104 are described in step S640.

[0225] like Figure 13 As shown, the fault diagnosis process of the fault diagnosis device applied to switching power amplifiers (such as magnetic bearing power amplifiers) also includes:

[0226] Step 3: Based on the current i detected by the current sensor m m Power amplifier bus current i n+1 With the current i of each coil n The switching signal and the second error threshold ε2 are used to determine whether they satisfy the following formula (11):

[0227]

[0228] If so, then determine the switching transistor Q. m1 or switching transistor Q m4 Fault. Otherwise, determine that the current sensor m is faulty.

[0229] The control unit 104 is further configured to determine that neither the switching transistor module nor the current coil current detection module in the current power amplifier module is faulty if the first current difference is less than or equal to the first error threshold, and to determine whether the bus current detection module is faulty based on the difference between the bus current and the first total current. The specific functions and processing of this control unit 104 are described in step S540.

[0230] In some embodiments, the control unit 104 determines whether the bus current detection module is faulty based on the difference between the bus current and the first total current, including:

[0231] The control unit 104 is further configured to determine the absolute value of the difference between the bus current and the first total current difference, denoted as the third current difference. The specific functions and processing of the control unit 104 are described in step S710.

[0232] The control unit 104 is further configured to determine whether the third current difference is less than or equal to a set second error threshold. The specific functions and processing of the control unit 104 are described in step S720.

[0233] The control unit 104 is further configured to determine that the switching transistor module, the current coil current detection module, and the bus current detection module in the current power amplifier module are all functioning correctly if the third current difference is less than or equal to the second error threshold. The specific functions and processing of this control unit 104 are described in step S730.

[0234] The control unit 104 is further configured to determine that the bus current detection module is faulty if the third current difference is greater than the second error threshold. The specific functions and processing of the control unit 104 are described in step S740.

[0235] like Figure 13 As shown, the fault diagnosis process of the fault diagnosis device applied to switching power amplifiers (such as magnetic bearing power amplifiers) also includes:

[0236] Step 4: Based on the power amplifier bus current i n+1 With the current i of each coil n The switching signal and the second error threshold ε2 are used to determine whether they satisfy the following formula (12):

[0237]

[0238] If so, then the power amplifier is faulty due to a lack of power switches and a faulty current sensor. Otherwise, the current sensor n+1 is faulty.

[0239] Figure 14 This is a current characteristic table for a power amplifier under different fault conditions. In the scheme of this invention, the current characteristic tables under different fault conditions are obtained as follows: Figure 14 As shown, ε2 is the second error threshold. It can be seen that different fault states have different current characteristics. The solution of the present invention can simultaneously diagnose power switch open circuit faults and current sensor faults.

[0240] In some implementations, the method further includes: in the event that any one of the n coil current detection modules fails, controlling the electromagnetic bearing power amplifier to operate in a fault-tolerant manner under the condition that any one coil current detection module fails, as detailed below:

[0241] The control unit 104 is further configured to, after fault diagnosis is performed on the electromagnetic bearing power amplifier, n coil current detection modules and the bus current detection module according to the bus current of the direct-current power supply and the coil current of each bearing coil of the electromagnetic bearing, if any coil current detection module among the n coil current detection modules is faulty, determine the sum of the product of the coil current detected by the remaining coil current detection modules among the n coil current detection modules and the corresponding power amplifier module switch signal, denoted as a third total current value. For specific functions and processing of the control unit 104, see step S810.

[0242] The control unit 104 is further configured to determine the difference between the bus current and the third total current value as the fault-tolerant current of the any coil current detection module in the fault condition. For specific functions and processing of the control unit 104, see step S820.

[0243] The control unit 104 is further configured to control the operation of the bearing coil corresponding to the any coil current detection module according to the fault-tolerant current. For specific functions and processing of the control unit 104, see step S830.

[0244] In combination with Figure 13 In the example shown, if it is finally diagnosed that the fault occurs in the current sensor m, according to formula (9), the fault-tolerant current value i' m instead of the current i m detected by the current sensor m, fault-tolerant operation under single sensor fault can be realized. Then the fault-tolerant current i' m of the current sensor m in the fault state is represented as:

[0245]

[0246] The scheme of the present application can realize the diagnosis of single power switch open circuit fault and single current sensor fault and fault-tolerant operation under single current sensor fault through formula (6) and formula (10).

[0247] The scheme of the present application proposes a fault diagnosis device applied to a switching power amplifier (such as an electromagnetic bearing power amplifier), gives a power amplifier fault diagnosis and fault-tolerant scheme, adds a current sensor on the bus of the power amplifier, uses the relationship between the coil current and the target current and the relationship between the coil current and the bus current to perform power amplifier diagnosis and fault-tolerant, realizes fault-tolerant control under single current sensor, can diagnose power switch open circuit fault and current sensor fault, realizes fault-tolerant of single current sensor, solves the problem that the magnetic levitation motor control system cannot operate when single current sensor fails, and improves the reliability of the magnetic levitation motor control system.

[0248] In the scheme of the application, in particular by the current detection device suitable for the two-level power amplifier, by using the characteristics of the two-level control without the freewheeling state, only one current sensor needs to be added, by cooperating with the software fault diagnosis and fault-tolerant algorithm, the diagnosis of the open circuit fault of the single power switch and the fault of the single current sensor can be realized by using the bus current and the coil current characteristics, and in the case of the fault of the single current sensor, the fault-tolerant operation under the single current sensor fault can be realized by replacing the fault sensor detection current with the fault-tolerant current, and the reliability of the magnetic levitation motor control system is improved. In the scheme of the application, only one current sensor n+1 is additionally added on the bus (i.e. the direct current bus) of the power amplifier, the measurement value of the newly added current sensor n+1 is used to diagnose the current sensor fault of the power amplifier and the open circuit fault of the power switch, and the fault-tolerant control under the single current sensor fault is realized, and the cost is low.

[0249] Since the processing and functions realized by the device of the embodiment are basically corresponding to the embodiments, principles and examples of the foregoing method, the description of the embodiment is not detailed, and the related description in the foregoing embodiments can be referred to, and will not be repeated here.

[0250] By adopting the technical scheme of the application, one current sensor is arranged on the bus of the power amplifier to detect the bus current of the power amplifier, and the current sensor at each coil of the power amplifier is used to detect the corresponding coil current, and then, according to the relationship between the coil current and the target current and the relationship between the coil current and the bus current, the diagnosis of the current sensor fault and the open circuit fault of the power switch in the power amplifier is realized, so that the fault condition of the power amplifier can be determined in time, and the stability of the magnetic levitation motor control system is improved.

[0251] According to the embodiment of the application, a magnetic levitation system corresponding to the control device of the power amplifier is also provided. The magnetic levitation system can include the control device of the power amplifier described above.

[0252] Since the processing and functions realized by the magnetic levitation system of the embodiment are basically corresponding to the embodiments, principles and examples of the foregoing device, the description of the embodiment is not detailed, and the related description in the foregoing embodiments can be referred to, and will not be repeated here.

[0253] By adopting the technical scheme of the application, one current sensor is arranged on the bus of the power amplifier to detect the bus current of the power amplifier, and the current sensor at each coil of the power amplifier is used to detect the corresponding coil current, and then, according to the relationship between the coil current and the target current and the relationship between the coil current and the bus current, the diagnosis of the current sensor fault and the open circuit fault of the power switch in the power amplifier is realized, so that the fault condition of the power amplifier can be determined in time, and the stability of the magnetic levitation motor control system is improved.

[0254] According to the embodiment of the present application, a storage medium corresponding to the control method of the power amplifier is also provided, which comprises a stored program, wherein when the program is running, the device where the storage medium is located performs the control method of the power amplifier as described above.

[0255] Since the processing and functions realized by the storage medium of the present embodiment are basically corresponding to the embodiments, principles and examples of the foregoing method, the description of the present embodiment will not be elaborated on the unexplained parts, which can be referred to the relevant description in the foregoing embodiments.

[0256] By adopting the technical solution of the present application, a current sensor is arranged on the bus of the power amplifier to detect the bus current of the power amplifier, and a current sensor is arranged at each coil of the power amplifier to detect the corresponding coil current, and then, according to the relationship between the coil current and the target current and the relationship between the coil current and the bus current, the diagnosis of the current sensor fault and the open circuit fault of the power switch in the power amplifier is realized, so as to realize the timely determination of the fault condition of the power amplifier, and the cost is low.

[0257] In summary, the person skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.

[0258] The above only describes the embodiments of the present application and is not used to limit the present application, and the present application can have various changes and variations for the person skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A control method for a power amplifier, characterized in that, The power amplifier is used in the magnetic levitation motor control system as an electromagnetic bearing power amplifier; the electromagnetic bearing power amplifier includes: n power amplifier modules, where n is a positive integer; the n power amplifier modules are arranged in parallel between the positive and negative terminals of the DC power supply on the input side of the electromagnetic bearing power amplifier; A bus current detection module is provided between the positive terminal of the DC power supply and the n power amplifier modules; the bus current detection module is configured to detect the current of the main circuit of the electromagnetic bearing power amplifier; a coil current detection module is provided between each power amplifier module and the corresponding bearing coil of the electromagnetic bearing; the coil current detection module is configured to detect the current of the corresponding bearing coil of the electromagnetic bearing. The control method for the power amplifier includes: The current of the main circuit of the electromagnetic bearing power amplifier detected by the bus current detection module is obtained and recorded as the bus current of the DC power supply; the current of the corresponding bearing coil of the electromagnetic bearing detected by the coil current detection module at each bearing coil of the electromagnetic bearing is obtained and recorded as the coil current of each bearing coil of the electromagnetic bearing. Based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing, fault diagnosis is performed on the electromagnetic bearing power amplifier, the n coil current detection modules, and the bus current detection module. This includes: based on the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module. Wherein, the current power amplifier module is the power amplifier module currently undergoing fault diagnosis among the n power amplifier modules; the current bearing coil of the electromagnetic bearing is the bearing coil corresponding to the current power amplifier module among the n bearing coils of the electromagnetic bearing. Specifically, based on the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module, including: Determine the change value of the coil current detected by the current coil current detection module within the set control cycle, and determine the current difference between the bus current and the n coil currents detected by the n coil current detection modules. Based on the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module; wherein, the current coil current is the coil current of the current bearing coil detected by the current coil current detection module at the current detection time; and the previous coil current is the coil current of the current bearing coil detected by the current coil current detection module at the previous detection time.

2. The control method for the power amplifier according to claim 1, characterized in that, Each of the power amplifier modules includes: a power switch module and a freewheeling module; the power switch module includes: a first switching transistor module and a second switching transistor module; the freewheeling module includes: a first diode module and a second diode module; The positive terminal of the DC power supply is connected to the first connection terminal of the first switching transistor module and the cathode of the first diode module in each power amplifier module after passing through the bus current detection module. The negative terminal of the DC power supply is connected to the anode of the second diode module and the second connection terminal of the second switching transistor module in each of the power amplifier modules. In each of the power amplifier modules, the second connection terminal of the first switching transistor module is connected to the cathode of the second diode module; in each of the power amplifier modules, the anode of the first diode module is connected to the first connection terminal of the second switching transistor module. The corresponding coil current detection module and the corresponding bearing coil of the electromagnetic bearing are set between the second connection terminal of the first switching tube module and the anode of the first diode module in each power amplifier module; The faults of the electromagnetic bearing power amplifier include any of the following: a fault in either the first switching transistor module or the second switching transistor module, or a fault in either the bus current detection module or any of the n coil current detection modules.

3. The control method for the power amplifier according to claim 1, characterized in that, in, Determining the change in coil current detected by the current coil current detection module within a set control period includes: Determine the rate of change of charging time and the rate of change of discharging time of the coil current detected by the current coil current detection module; Combining the charging state duty cycle and discharging state duty cycle of the electromagnetic bearing power amplifier, and the set control cycle, the sum of the product of the charging state duty cycle and the charging time change rate, and the product of the discharging state duty cycle and the discharging time change rate, and then multiplying it by the control cycle, is determined as the change value of the coil current detected by the current coil current detection module. And / or, Determining the current difference between the bus current and the n coil currents detected by the n coil current detection modules includes: The sum of the n coil currents detected by the n coil current detection modules is determined; wherein, the sum of the n coil currents detected by the n coil current detection modules is a first total current value or a second total current value. The difference between the bus current and the first total current value is determined as the first total current difference; the difference between the bus current and the second total current value is determined as the second total current difference; and the first total current difference or the second total current difference is used as the current difference between the bus current and the n coil currents detected by the n coil current detection modules. in, The first total current value refers to the sum of the products of the coil current detected by the first coil current detection module and the switching signal of the corresponding power amplifier module, up to the sum of the products of the coil current detected by the nth coil current detection module and the switching signal of the corresponding power amplifier module. Alternatively, the second total current value refers to: the sum of the product of the coil current detected by the first coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the (m-1)th coil current detection module and the switching signal of the corresponding power amplifier module, the sum of the product of the coil current detected by the (m+1)th coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the nth coil current detection module and the switching signal of the corresponding power amplifier module, and the sum of the coil current detected by the mth coil current detection module, which is denoted as the second total current value.

4. The control method for the power amplifier according to claim 3, characterized in that, Based on the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module, including: The absolute value of the difference between the current coil current detected by the current coil current detection module, the previous coil current detected by the current coil current detection module, and the change value of the coil current detected by the current coil current detection module is denoted as the first current difference. Determine whether the first current difference is greater than a set first error threshold; If the first current difference is greater than the first error threshold, then it is determined that the switching transistor module in the current power amplifier module is faulty or the current coil current detection module is faulty, and the fault type is determined according to the difference between the bus current and the second total current. If the first current difference is less than or equal to the first error threshold, it is determined that the switching transistor module and the current coil current detection module in the current power amplifier module are not faulty, and the bus current detection module is determined to be faulty based on the difference between the bus current and the first total current.

5. The control method for a power amplifier according to claim 3, characterized in that, in, The fault type is determined based on the difference between the bus current and the second total current, including: Determine the absolute value of the difference between the bus current and the second total current difference, and denot it as the second current difference. Determine whether the second current difference is less than or equal to the set second error threshold; If the second current difference is less than or equal to the second error threshold, then the switching transistor module in the current power amplifier module is determined to be faulty. If the second current difference is greater than the second error threshold, then the current coil current detection module is determined to be faulty; And / or, Determining whether the bus current detection module is faulty based on the difference between the bus current and the first total current includes: The absolute value of the difference between the bus current and the first total current difference is determined and denoted as the third current difference. Determine whether the third current difference is less than or equal to the set second error threshold; If the third current difference is less than or equal to the second error threshold, then it is determined that the switching transistor module, the current coil current detection module, and the bus current detection module in the current power amplifier module are all functioning correctly. If the third current difference is greater than the second error threshold, then the bus current detection module is determined to be faulty.

6. The control method for a power amplifier according to any one of claims 1 to 5, characterized in that, Also includes: If any one of the n coil current detection modules fails, the sum of the products of the coil current detected by the remaining coil current detection modules and the corresponding power amplifier module's switching signal is determined and recorded as the third total current value. The difference between the bus current and the third total current value is determined as the fault-tolerant current of any coil current detection module under fault conditions. The bearing coil corresponding to any coil current detection module is controlled to operate according to the fault-tolerant current.

7. A control device for a power amplifier that uses the power amplifier control method as described in claim 1 to achieve power amplifier control, characterized in that, The power amplifier is used in the magnetic levitation motor control system as an electromagnetic bearing power amplifier; the electromagnetic bearing power amplifier includes: n power amplifier modules, where n is a positive integer; the n power amplifier modules are arranged in parallel between the positive and negative terminals of the DC power supply on the input side of the electromagnetic bearing power amplifier; A bus current detection module is provided between the positive terminal of the DC power supply and the n power amplifier modules; the bus current detection module is configured to detect the current of the main circuit of the electromagnetic bearing power amplifier; a coil current detection module is provided between each power amplifier module and the corresponding bearing coil of the electromagnetic bearing; the coil current detection module is configured to detect the current of the corresponding bearing coil of the electromagnetic bearing. The control device for the power amplifier includes: The acquisition unit is configured to acquire the current of the main circuit of the electromagnetic bearing power amplifier detected by the bus current detection module, and record it as the bus current of the DC power supply; and acquire the current of the corresponding bearing coil of the electromagnetic bearing detected by the coil current detection module at each bearing coil of the electromagnetic bearing, and record it as the coil current of each bearing coil of the electromagnetic bearing. The control unit is configured to perform fault diagnosis on the electromagnetic bearing power amplifier, n coil current detection modules, and the bus current detection module based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing.

8. The control device for the power amplifier according to claim 7, characterized in that, Each of the power amplifier modules includes: a power switch module and a freewheeling module; the power switch module includes: a first switching transistor module and a second switching transistor module; the freewheeling module includes: a first diode module and a second diode module; The positive terminal of the DC power supply is connected to the first connection terminal of the first switching transistor module and the cathode of the first diode module in each power amplifier module after passing through the bus current detection module. The negative terminal of the DC power supply is connected to the anode of the second diode module and the second connection terminal of the second switching transistor module in each of the power amplifier modules. In each of the power amplifier modules, the second connection terminal of the first switching transistor module is connected to the cathode of the second diode module; in each of the power amplifier modules, the anode of the first diode module is connected to the first connection terminal of the second switching transistor module. The corresponding coil current detection module and the corresponding bearing coil of the electromagnetic bearing are set between the second connection terminal of the first switching tube module and the anode of the first diode module in each power amplifier module; The faults of the electromagnetic bearing power amplifier include any of the following: a fault in either the first switching transistor module or the second switching transistor module, or a fault in either the bus current detection module or any of the n coil current detection modules.

9. The control device for the power amplifier according to claim 8, characterized in that, The control unit performs fault diagnosis on the electromagnetic bearing power amplifier, the n coil current detection modules, and the bus current detection module based on the bus current of the DC power supply and the coil current of each bearing coil of the electromagnetic bearing, including: Based on the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module; wherein, the current power amplifier module is one of the n power amplifier modules currently undergoing fault diagnosis; the current bearing coil of the electromagnetic bearing is the bearing coil corresponding to the current power amplifier module among the n bearing coils of the electromagnetic bearing. in, The control unit performs fault diagnosis on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module based on the bus current of the DC power supply and the coil current of the current bearing coil of the electromagnetic bearing. This includes: Determine the change value of the coil current detected by the current coil current detection module within the set control cycle, and determine the current difference between the bus current and the n coil currents detected by the n coil current detection modules. Based on the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules, fault diagnosis is performed on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module; wherein, the current coil current is the coil current of the current bearing coil detected by the current coil current detection module at the current detection time; and the previous coil current is the coil current of the current bearing coil detected by the current coil current detection module at the previous detection time.

10. The control device for the power amplifier according to claim 9, characterized in that, in, The control unit determines the change in coil current detected by the current coil current detection module within a set control period, including: Determine the rate of change of charging time and the rate of change of discharging time of the coil current detected by the current coil current detection module; Combining the charging state duty cycle and discharging state duty cycle of the electromagnetic bearing power amplifier, and the set control cycle, the sum of the product of the charging state duty cycle and the charging time change rate, and the product of the discharging state duty cycle and the discharging time change rate, and then multiplying it by the control cycle, is determined as the change value of the coil current detected by the current coil current detection module. And / or, The control unit determines the current difference between the bus current and the n coil currents detected by the n coil current detection modules, including: The sum of the n coil currents detected by the n coil current detection modules is determined; wherein, the sum of the n coil currents detected by the n coil current detection modules is a first total current value or a second total current value. The difference between the bus current and the first total current value is determined as the first total current difference; the difference between the bus current and the second total current value is determined as the second total current difference; and the first total current difference or the second total current difference is used as the current difference between the bus current and the n coil currents detected by the n coil current detection modules. in, The first total current value refers to the sum of the products of the coil current detected by the first coil current detection module and the switching signal of the corresponding power amplifier module, up to the sum of the products of the coil current detected by the nth coil current detection module and the switching signal of the corresponding power amplifier module. Alternatively, the second total current value refers to: the sum of the product of the coil current detected by the first coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the (m-1)th coil current detection module and the switching signal of the corresponding power amplifier module, the sum of the product of the coil current detected by the (m+1)th coil current detection module and the switching signal of the corresponding power amplifier module up to the sum of the product of the coil current detected by the nth coil current detection module and the switching signal of the corresponding power amplifier module, and the sum of the coil current detected by the mth coil current detection module, which is denoted as the second total current value.

11. The control device for the power amplifier according to claim 10, characterized in that, The control unit performs fault diagnosis on the switching transistor module in the current power amplifier module of the electromagnetic bearing power amplifier, the current coil current detection module at the current bearing coil of the electromagnetic bearing, and the bus current detection module, based on the current coil current and the previous coil current detected by the current coil current detection module, the change value of the coil current detected by the current coil current detection module, and the current difference between the bus current and the n coil currents detected by the n coil current detection modules. This includes: The absolute value of the difference between the current coil current detected by the current coil current detection module, the previous coil current detected by the current coil current detection module, and the change value of the coil current detected by the current coil current detection module is denoted as the first current difference. Determine whether the first current difference is greater than a set first error threshold; If the first current difference is greater than the first error threshold, then it is determined that the switching transistor module in the current power amplifier module is faulty or the current coil current detection module is faulty, and the fault type is determined according to the difference between the bus current and the second total current. If the first current difference is less than or equal to the first error threshold, it is determined that the switching transistor module and the current coil current detection module in the current power amplifier module are not faulty, and the bus current detection module is determined to be faulty based on the difference between the bus current and the first total current.

12. The control device for the power amplifier according to claim 11, characterized in that, in, The control unit determines the fault type based on the difference between the bus current and the second total current, including: Determine the absolute value of the difference between the bus current and the second total current difference, and denot it as the second current difference. Determine whether the second current difference is less than or equal to the set second error threshold; If the second current difference is less than or equal to the second error threshold, then the switching transistor module in the current power amplifier module is determined to be faulty. If the second current difference is greater than the second error threshold, then the current coil current detection module is determined to be faulty; And / or, The control unit determines whether the bus current detection module is faulty based on the difference between the bus current and the first total current, including: The absolute value of the difference between the bus current and the first total current difference is determined and denoted as the third current difference. Determine whether the third current difference is less than or equal to the set second error threshold; If the third current difference is less than or equal to the second error threshold, then it is determined that the switching transistor module, the current coil current detection module, and the bus current detection module in the current power amplifier module are all functioning correctly. If the third current difference is greater than the second error threshold, then the bus current detection module is determined to be faulty.

13. The control device for the power amplifier according to any one of claims 7 to 12, characterized in that, Also includes: The control unit is further configured to, if any one of the n coil current detection modules fails, determine the sum of the products of the coil current detected by the remaining coil current detection modules and the switching signal of the corresponding power amplifier module, and record it as the third total current value. The control unit is further configured to determine the difference between the bus current and the third total current value as the fault-tolerant current of the any coil current detection module in the event of a fault. The control unit is also configured to control the bearing coil corresponding to any coil current detection module to operate according to the fault-tolerant current.

14. A magnetic levitation system, characterized in that, include: The control device for the power amplifier as described in any one of claims 7 to 13.

15. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, the device containing the storage medium is controlled to perform the control method of the power amplifier as described in any one of claims 1 to 6.

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