A magnetic bearing system and power amplification device and fault detection method thereof

Abstract

The application discloses a power amplification device of a magnetic bearing system, the magnetic bearing system and a fault detection method thereof. The device comprises: first and second H-bridge circuits which are cascaded and redundantly arranged; a selection switch unit which is capable of being switched to connect the bearing coil with any one of the first and second H-bridge circuits; and a magnetic bearing controller which is capable of controlling the magnetic bearing to stop working when it is determined that the bearing coil is faulty, and is capable of controlling the selection switch unit to connect the other H-bridge circuit with the bearing coil to supply power to the bearing coil so as to make the magnetic bearing continue to work when it is determined that a power device in the H-bridge circuit currently connected with the bearing coil is faulty. According to the scheme, whether the bearing coil and the power device are faulty and the fault point is located by detecting the current of the bearing coil and the action of the selection switch unit, and the H-bridge circuit redundantly arranged is switched when the power device is faulty, so that time and labor are saved, and the reliability is good.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of magnetic bearing system, and particularly relates to a power amplification device of a magnetic bearing system, a magnetic bearing system with the power amplification device, and a fault detection method of the magnetic bearing system, and particularly relates to a power amplification circuit of a magnetic bearing system, a magnetic bearing system with the power amplification circuit, and a fault detection method of the magnetic bearing system and the power amplification circuit thereof. BACKGROUND

[0002] A magnetic bearing (magnetic suspension bearing) is a new type of bearing that uses an electromagnet to generate a controllable electromagnetic force to suspend a rotor for non-contact support. A magnetic bearing system (i.e., a magnetic bearing and a magnetic bearing control system) detects the real-time displacement of the rotor through a displacement sensor, processes the output control signal through an MCU, and outputs the required current of the electromagnet through a power amplification circuit to provide electromagnetic force to achieve the suspension of the rotor at the middle position. In actual application, the damage, false triggering of the power device in the power amplification circuit, and the open circuit fault of the bearing coil will cause the magnetic bearing current (i.e., the current of the bearing coil) to be abnormal, thereby causing the rotor to be unable to normally suspend. In related solutions, when a fault occurs in the power amplification circuit, a detection device needs to be used to gradually check and locate the problem point (i.e., the fault point) of the hardware of the power amplification circuit, which requires a large amount of time and manpower.

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

[0004] The present application aims to provide a power amplification device of a magnetic bearing system, a magnetic bearing system, and a fault detection method thereof, to solve the problem that when the magnetic bearing system and the control system thereof fail, manual detection equipment needs to be used to gradually check and locate the fault point, which is time-consuming and labor-intensive, to achieve the effect of detecting whether the magnetic bearing system fails and locating the fault point by selecting the action of the switch unit according to the current of the bearing coil, and switching the redundant power amplification branch when the power device fails to make the magnetic bearing work normally, saving time and labor, and ensuring the reliability of the magnetic bearing system.

[0005] The application provides a power amplifier device of a magnetic bearing system, the magnetic bearing system comprising a magnetic bearing and a magnetic bearing control system; the magnetic bearing comprising a bearing coil; the magnetic bearing control system comprising the power amplifier device and a magnetic bearing controller; the power amplifier device of the magnetic bearing system comprising a first H-bridge circuit, a second H-bridge circuit and a selection switch unit; wherein the first H-bridge circuit and the second H-bridge circuit are cascaded, and the first H-bridge circuit and the second H-bridge circuit are power amplifier branches arranged redundantly with each other; a first end of the bearing coil is connected to the selection switch unit, and a second end of the bearing coil is connected to the first H-bridge circuit and the second H-bridge circuit respectively; the selection switch unit is capable of being switched to connect the bearing coil to any one of the first H-bridge circuit and the second H-bridge circuit; one of the first H-bridge circuit and the second H-bridge circuit currently connected to the bearing coil is recorded as a current H-bridge circuit; the magnetic bearing controller is used to determine whether the magnetic bearing system fails according to a current of the bearing coil in combination with controlling the selection switch unit; the failure of the magnetic bearing system comprises at least one of the following: a failure of the bearing coil and a failure of a power device in the current H-bridge circuit; and if it is determined that the bearing coil fails, the magnetic bearing is controlled to stop working; if it is determined that the power device in the current H-bridge circuit fails, the selection switch unit is controlled to connect the other one of the first H-bridge circuit and the second H-bridge circuit to the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to work.

[0006] In some embodiments, the selection switch unit comprises: a first switch and a second switch; the first H-bridge circuit comprises: a first power device and a second power device; the second H-bridge circuit comprises: a third power device and a fourth power device; wherein the control end of the first switch is used for receiving the first PWM signal sent by the magnetic bearing controller; the first connection end of the first switch is connected with the control end of the first power device; the first connection end of the first power device is connected with a direct current power supply; the second connection end of the first switch is connected with the control end of the third power device; the first connection end of the third power device is connected with the direct current power supply; the control end of the second switch is connected with the first end of the bearing coil; the first connection end of the second switch is connected with the second connection end of the first power device; the second connection end of the second switch is connected with the second connection end of the third power device; the control end of the second power device is used for receiving the second PWM signal sent by the magnetic bearing controller; the first connection end of the second power device is connected with the second end of the bearing coil; the second connection end of the second power device is grounded; the control end of the fourth power device is used for receiving the third PWM signal sent by the magnetic bearing controller; the first connection end of the fourth power device is connected with the second end of the bearing coil; and the second connection end of the fourth power device is grounded.

[0007] In some embodiments, the first H-bridge circuit further comprises: a first diode and a second diode; the second H-bridge circuit further comprises: a third diode and a fourth diode; wherein the cathode of the first diode is connected with a direct current power supply, and the anode of the first diode is connected with the second end of the bearing coil; the cathode of the second diode is connected with the first end of the bearing coil, and the anode of the second diode is grounded; the cathode of the third diode is connected with the first end of the bearing coil, and the anode of the third diode is grounded; the cathode of the fourth diode is connected with a direct current power supply, and the anode of the fourth diode is connected with the second end of the bearing coil.

[0008] In some embodiments, further comprising: a current detection unit; wherein the current detection unit is arranged at the second end of the bearing coil, and is used for detecting the current of the bearing coil and transmitting to the magnetic bearing controller.

[0009] In order to match the above-mentioned device, the present application further provides a magnetic bearing system, comprising: the power amplification device of the magnetic bearing system.

[0010] In another aspect, the present application provides a fault detection method for a magnetic bearing system, which is matched with the magnetic bearing system described above, and comprises: setting the current H-bridge circuit as the first H-bridge circuit, obtaining the current of the bearing coil under the condition that the first H-bridge circuit is connected with the bearing coil; determining whether the magnetic bearing system has a fault according to the current of the bearing coil and in combination with the control of the selection switch unit; the fault of the magnetic bearing system includes at least one of the following: a fault of the bearing coil and a fault of a power device in the first H-bridge circuit; and if it is determined that the bearing coil has a fault, the magnetic bearing is controlled to stop working; if it is determined that the power device in the first H-bridge circuit has a fault, the selection switch unit is controlled to connect the second H-bridge circuit with the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to work.

[0011] In some embodiments, the power device in the first H-bridge circuit includes a first power device and a second power device, the power device in the second H-bridge circuit includes a third power device and a fourth power device; the fault of the power device in the first H-bridge circuit includes at least one of the following: a fault of the first power device and a fault of the second power device; the selection switch unit includes a first switch and a second switch; the determination of whether the magnetic bearing system has a fault according to the current of the bearing coil and in combination with the control of the selection switch unit includes: in a current control period, it is firstly determined whether the current of the bearing coil is greater than a set maximum current; if it is firstly determined that the current of the bearing coil is greater than the set maximum current, the second switch in the selection switch unit is controlled to act to stop sending a first PWM signal to a control end of the first power device in the first H-bridge circuit and to send the first PWM signal to a control end of the third power device in the second H-bridge circuit, and then it is determined again whether the current of the bearing coil is greater than the set maximum current; if it is determined again that the current of the bearing coil is greater than the set maximum current, it is determined that the first power device has a breakdown fault, and a prompt message of the breakdown fault of the first power device is initiated; if it is determined again that the current of the bearing coil is less than or equal to the set maximum current, it is determined that the second power device in the first H-bridge circuit has a breakdown fault, and a prompt message of the breakdown fault of the second power device is initiated.

[0012] In some embodiments, in combination with controlling the selection switch unit, determining whether the magnetic bearing system fails according to the current of the bearing coil further comprises: if the current of the bearing coil is determined to be less than or equal to the set maximum current for the first time, determining whether the current of the bearing coil is equal to 0 for the first time; if the current of the bearing coil is determined not to be equal to 0 for the first time, determining that neither the bearing coil nor the power device in the first H-bridge circuit fails, and still making the first H-bridge circuit supply power to the bearing coil to make the magnetic bearing continue to work; if the current of the bearing coil is determined to be equal to 0 for the first time, outputting a third PWM signal to make the third PWM signal output the same PWM wave as the second PWM signal to control the fourth power device in the second H-bridge circuit to be turned on, and then determining whether the current of the bearing coil is equal to 0 for the second time; if the current of the bearing coil is determined to be equal to 0 for the second time, controlling the first switch and the second switch in the selection switch unit to act simultaneously to make the first H-bridge circuit connected to the bearing coil and switch to make the second H-bridge circuit connected to the bearing coil, and then continue to determine whether the bearing coil and the power device in the first H-bridge circuit fail; and if the current of the bearing coil is determined not to be equal to 0 for the second time, determining that the second power device fails in open circuit, and initiating a prompt message that the second power device fails in open circuit, and then continue to determine whether the bearing coil and the power device in the first H-bridge circuit fail.

[0013] In some embodiments, continuing to determine whether the bearing coil and the power device in the first H-bridge circuit fail comprises: determining whether the current of the bearing coil is equal to 0 for the third time; if the current of the bearing coil is determined not to be equal to 0 for the third time, determining that the bearing coil fails in open circuit; and if the current of the bearing coil is determined to be equal to 0 for the third time, determining that the first power device fails in open circuit, and initiating a prompt message that the first power device fails in open circuit.

[0014] In some embodiments, the power devices in the first H-bridge circuit include a first power device and a second power device, the power devices in the second H-bridge circuit include a third power device and a fourth power device; the failure of the power devices in the first H-bridge circuit includes at least one of the following: failure of the first power device, failure of the second power device; the selection switch unit includes a first switch and a second switch; if it is determined that the power devices in the first H-bridge circuit fail, the selection switch unit is controlled to connect the second H-bridge circuit to the bearing coil to supply power to the bearing coil to enable the magnetic bearing to continue to work, including at least one of the following: if it is determined that the first power device fails or it is determined that the second power device in the first H-bridge circuit fails, the first switch in the selection switch unit is controlled to switch from a state in which the first power device in the first H-bridge circuit is connected to the bearing coil to a state in which the third power device in the second H-bridge circuit is connected to the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil, a third PWM signal is sent, and the third PWM signal output is the same as the second PWM signal to enable the magnetic bearing to continue to work; if it is determined that the first power device fails or it is determined that the second power device fails, in the case where the third PWM signal is sent to make the third PWM signal output the same as the second PWM signal, the first switch and the second switch in the selection switch unit are controlled to act simultaneously to switch from a state in which the first H-bridge circuit is connected to the bearing coil to a state in which the second H-bridge circuit is connected to the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil to enable the magnetic bearing to continue to work.

[0015] Therefore, the scheme of the present application, for the power amplifier circuit of the control system of the magnetic bearing, provides a selection switch unit and two H-bridge circuits, the two H-bridge circuits are connected in cascade, the first end of the bearing coil is connected to the selection switch unit, the second end of the bearing coil is connected to the two H-bridge circuits respectively, and the two H-bridge circuits are switched to be connected to the bearing coil by controlling the selection switch; in the case where the magnetic bearing works, whether the bearing coil and the two H-bridge circuits of the magnetic bearing system fail and the failure point is determined according to the current of the bearing coil, and the two H-bridge circuits are switched to enable the magnetic bearing to work normally when a failure occurs; thus, by providing a redundant power amplifier branch for the power amplifier circuit of the control system of the magnetic bearing, whether the magnetic bearing system fails and the failure point is located according to the current of the bearing coil and the action of the selection switch unit, and the power amplifier branch is switched to enable the magnetic bearing to work normally when a power device fails, the failure point can be detected conveniently and reliably, and the normal work of the magnetic bearing system is ensured to ensure the reliability of the magnetic bearing system.

[0016] Other features and advantages of the present application will be set forth in the following description, and in part will be apparent from the description, or can be learned by practice of the application.

[0017] The technical solutions of the present application will be further described in detail below with the help of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Structure diagram of an embodiment of the power amplification device of the magnetic bearing system of the present application;

[0019] Figure 2 Structure diagram of an embodiment of the power amplification circuit of the magnetic bearing system in the related solutions;

[0020] Figure 3 Structure diagram of an embodiment of the power amplification circuit of the magnetic bearing system of the present application;

[0021] Figure 4 Logic diagram of the fault judgment control of an embodiment of the fault detection method of the magnetic bearing system of the present application;

[0022] Figure 5 Flow diagram of an embodiment of the fault detection method of the magnetic bearing system of the present application;

[0023] Figure 6 Flow diagram of an embodiment of the first process of determining whether the magnetic bearing system has a fault in the method of the present application;

[0024] Figure 7 Flow diagram of an embodiment of the second process of determining whether the magnetic bearing system has a fault in the method of the present application;

[0025] Figure 8 Flow diagram of an embodiment of the process of continuously determining whether the bearing coil and the power devices in the first H-bridge circuit have a fault in the method of the present application.

[0026] In combination with the accompanying drawings, the reference signs in the embodiments of the present application are as follows:

[0027] 1, 2-analog selection switch. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work, fall within the protection scope of the present application.

[0029] Figure 2 This is a schematic diagram of one embodiment of the power amplifier circuit of the magnetic bearing system in a related scheme. (See diagram below.) Figure 2 The power amplifier circuit of the magnetic bearing system shown, i.e., the power amplifier circuit of the magnetic levitation bearing control system, includes: a switching transistor. Switch S2, diode ,diode In the switching transistor and switching transistor When all transistors are MOSFETs, the DC power supply V cc With switching transistor The drains are connected, and the switching transistor is... source and diode The cathode is connected, diode The anode is grounded; DC power supply V cc Also with diodes The cathode is connected, diode anode and switching transistor The drains are connected, and the switching transistor is switched. The source is grounded. In a magnetic bearing system, the first connection terminal of the bearing coil of the magnetic bearing is connected to the diode. The cathode is connected, and the second connection terminal of the bearing coil is connected to the diode. The anode is connected.

[0030] In the relevant scheme, the power amplifier circuit of the magnetic levitation bearing control system is Figure 2 The H-bridge three-level power amplifier circuit shown has a switching transistor. and switching transistor When both are turned on, the bearing coil is in a charging state, and the current in the bearing coil increases; the switching transistor Turn off, switching transistor When switched on, the bearing coil is in freewheeling mode, and the switching transistor... and diodes Forming a freewheeling circuit; switching transistor and switching transistor When simultaneously turned off, the bearing coil discharges and feeds back the bus voltage, and the bearing coil is in a discharging state. These three states constitute a three-level power amplifier circuit. When any of the switching transistors or the bearing coil fails, the magnetic bearing will not operate normally. Troubleshooting requires disassembling the magnetic bearing controller and checking each component one by one.

[0031] When the magnetic bearing and its control system need to be stopped due to faults, each element needs to be disassembled and checked by detection equipment to locate the fault point, which consumes a lot of manpower and time. The scheme of the present application provides a power amplification circuit of a magnetic bearing system and a fault detection scheme of the magnetic bearing system and the power amplification circuit thereof, which can automatically detect faults of the magnetic bearing system and the power amplification circuit thereof and report the fault point to the upper computer, and can ensure the normal operation of the magnetic suspension bearing when the power device fails, thereby saving time and labor to detect the fault point and ensuring the normal operation of the magnetic bearing system and the reliability of the magnetic bearing system.

[0032] According to an embodiment of the present application, a power amplification device of a magnetic bearing system is provided. Referring to Figure 1 The magnetic bearing system has a magnetic bearing and a magnetic bearing control system; the magnetic bearing has a bearing coil; the magnetic bearing control system has a power amplification device and a magnetic bearing controller, and the magnetic bearing controller has a master control chip (such as MCU); the power amplification device of the magnetic bearing system, i.e. the power amplification device of the magnetic bearing control system, comprises a first H-bridge circuit, a second H-bridge circuit and a selection switch unit.

[0033] The first H-bridge circuit and the second H-bridge circuit are cascaded, and the first H-bridge circuit and the second H-bridge circuit are redundantly arranged as power amplification branches. The first end of the bearing coil is connected to the selection switch unit, and the second end of the bearing coil is connected to the first H-bridge circuit and the second H-bridge circuit respectively. The selection switch unit can be switched to connect the bearing coil to any one of the first H-bridge circuit and the second H-bridge circuit under the control of the magnetic bearing controller, so as to connect any one of the first H-bridge circuit and the second H-bridge circuit to the bearing coil to supply power to the bearing coil; one of the first H-bridge circuit and the second H-bridge circuit currently connected to the bearing coil is referred to as a current H-bridge circuit.

[0034] The magnetic bearing controller is configured to determine whether the magnetic bearing system has a fault according to the current of the bearing coil and control the selection switch unit; the fault of the magnetic bearing system includes at least one of the following: a fault of the bearing coil and a fault of a power device in the current H-bridge circuit.

[0035] The magnetic bearing controller is further configured to control the magnetic bearing to stop working if it is determined that the bearing coil has a fault, specifically to control the magnetic bearing to stop floating due to shaft failure.

[0036] The magnetic bearing controller is further configured to, if it is determined that a power device in the current H-bridge circuit fails, control the selection switch unit to connect another H-bridge circuit in the first H-bridge circuit and the second H-bridge circuit to the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to work. Specifically, the magnetic bearing controller determines whether the magnetic bearing system fails according to the current of the bearing coil when the current H-bridge circuit supplies power to the bearing coil, in particular, when one of the first H-bridge circuit and the second H-bridge circuit currently connected to the bearing coil supplies power to the bearing coil to make the magnetic bearing work. If the power device in the one of the first H-bridge circuit and the second H-bridge circuit currently connected to the bearing coil fails, the selection switch unit is used to connect the other H-bridge circuit in the first H-bridge circuit and the second H-bridge circuit to the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to work. That is, if the power device in the one of the first H-bridge circuit and the second H-bridge circuit currently connected to the bearing coil fails, the selection switch unit is used to connect the other H-bridge circuit in the first H-bridge circuit and the second H-bridge circuit to the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to work.

[0037] The power amplification circuit of the magnetic bearing system and the fault detection scheme of the magnetic bearing system and the power amplification circuit thereof provided in the scheme of the present application can automatically detect the fault of the magnetic bearing system and the power amplification circuit thereof according to the current of the bearing coil and report the fault point to the upper computer by using the current sensor to detect the current of the bearing coil. The fault is detected at the same time as the switching to the normally working circuit. The fault point can be avoided when the power device fails, and the stable work can be continued. The fault point can be detected time-savingly and labor-savingly, and the normal work of the magnetic bearing system can be ensured to ensure the reliability of the magnetic bearing system.

[0038] In some embodiments, the selection switch unit includes a first switch and a second switch, the first switch is analog selection switch 1, and the second switch is analog selection switch 2. The first H-bridge circuit includes a first power device and a second power device, the first power device is switch tube S1, and the second power device is switch tube S2. The second H-bridge circuit includes a third power device and a fourth power device, the third power device is switch tube S3, and the fourth power device is switch tube S4.

[0039] The control terminal of the first switch is used to receive the first PWM signal from the magnetic bearing controller; the first connection terminal of the first switch is connected to the control terminal of the first power device (e.g., connected to the gate of the switching transistor S1); the first connection terminal of the first power device is connected to a DC power supply (e.g., the drain of the switching transistor S1 is connected to a DC power supply V). cc The second connection terminal of the first switch is connected to the control terminal of the third power device (e.g., connected to the gate of the switching transistor S3); the first connection terminal of the third power device is connected to a DC power supply (e.g., the drain of the switching transistor S3 is connected to a DC power supply V). cc The control terminal of the second switch is connected to the first terminal of the bearing coil; the first connection terminal of the second switch is connected to the second connection terminal of the first power device (e.g., connected to the source of the switching transistor S1); the second connection terminal of the second switch is connected to the second connection terminal of the third power device (e.g., connected to the source of the switching transistor S3).

[0040] The control terminal of the second power device (such as the gate of the switching transistor S2) is used to receive the second PWM signal emitted by the magnetic bearing controller; the first connection terminal of the second power device (such as the drain of the switching transistor S2) is connected to the second terminal of the bearing coil; the second connection terminal of the second power device (such as the source of the switching transistor S2) is grounded. The control terminal of the fourth power device (such as the gate of the switching transistor S4) is used to receive the third PWM signal emitted by the magnetic bearing controller; the first connection terminal of the fourth power device (such as the drain of the switching transistor S4) is connected to the second terminal of the bearing coil; the second connection terminal of the fourth power device (such as the source of the switching transistor S4) is grounded.

[0041] Figure 3 This is a schematic diagram of the power amplifier circuit of the magnetic bearing system of the present invention. Figure 3 The power amplifier circuit of the magnetic bearing system proposed in the present invention consists of two cascaded H-bridge circuits, two analog selection switches (such as analog selection switch 1 and analog selection switch 2), and a current sensor for the user to measure the current of the bearing coil. The two H-bridge circuits are powered by the same power supply, such as a DC power supply V. cc Power supply; three PWM waves (i.e., the first PWM signal, the second PWM signal, and the third PWM signal) control the switching transistors respectively. Switching transistor Switching transistor Switching transistor The two analog selector switches are controlled by control signals from the MCU of the magnetic bearing controller.

[0042] The scheme of the application automatically checks the fault point through the opening and closing of the analog selection switch and reports the fault point on the upper computer, detects the fault point while switching to the circuit that can work normally, so that the magnetic suspension bearing can work normally during the period of waiting for the technical personnel to solve the fault, saves time and labor, and ensures reliable operation of the magnetic suspension bearing.

[0043] In some embodiments, the first H-bridge circuit further comprises a first diode and a second diode, and the second H-bridge circuit further comprises a third diode and a fourth diode.

[0044] The cathode of the first diode is connected to a DC power supply, and the anode of the first diode is connected to the second end of the bearing coil; the anode of the second diode is connected to the first end of the bearing coil, and the cathode of the second diode is grounded. The anode of the third diode is connected to the first end of the bearing coil, and the cathode of the third diode is grounded; the cathode of the fourth diode is connected to a DC power supply, and the anode of the fourth diode is connected to the second end of the bearing coil.

[0045] In the power amplification circuit of the magnetic bearing system as Figure 3 shown, specifically includes: switch tube , switch tube , switch tube , switch tube , diode , diode , diode , diode , analog selection switch 1 and analog selection switch 2, and a current sensor arranged at the second end of the bearing coil. Switch tube , switch tube , diode , diode constitute an H-bridge circuit, switch tube , switch tube , diode , diode constitute another H-bridge circuit. Wherein, in the case that switch tube , switch tube , switch tube , switch tube are MOS tubes, the DC power supply V cc is connected to the drain of switch tube , the source of switch tube is connected to the first connection end of analog selection switch 1, and the source of switch tube The gate of analog selector switch 2 is connected to the first connection terminal of analog selector switch 2, and the second connection terminal of analog selector switch 2 is connected to the switching transistor. The gate of analog selector switch 1 is connected to the control terminal of analog selector switch 2, which is connected to the input terminal of the first PWM signal. The second connection terminal of analog selector switch 1 is connected to the switching transistor. The source terminal is connected to the diode, and the control terminal of analog selector switch 1 is connected to the first connection terminal of the bearing coil; the second connection terminal of the bearing coil is connected to the diode via a current sensor. The anode is connected. DC power supply V cc Also with diodes The cathode is connected, diode anode and switching transistor The drains are connected, and the switching transistor is switched. The source is grounded to GND, and the switching transistor is connected to the ground. The gate of the diode is connected to the input terminal of the second PWM signal. The cathode of the diode is connected to the first connection terminal of the bearing coil. The anode is grounded (GND). DC power supply V cc Also with switching transistors The drain is connected. DC power supply V cc Also with diodes The cathode is connected, diode anode and diode The anode is connected. Diode The cathode is connected to the first end of the bearing coil, and the diode... The anode is grounded to GND. Switching transistor. The gate of the switching transistor is connected to the input terminal of the third PWM signal. Drain and diode The anode is connected, and the switching transistor is connected. The source terminal is grounded to GND.

[0046] The present invention detects the current of the bearing coil and determines the fault point based on the current of the bearing coil and the action of the selection switch unit. This allows the magnetic levitation bearing control system to automatically report the fault point and change the circuit connection to operate normally when a power device fault is detected. For example, a redundant design structure is adopted for the power amplifier circuit. When one of the power amplifier circuits is detected to be damaged, the other circuit can be replaced, saving troubleshooting time and manpower and improving production efficiency.

[0047] In some embodiments, the power amplification device of the magnetic bearing system according to the scheme of the present application further comprises a current detection unit (such as a current sensor); wherein the current detection unit is arranged at the second end of the bearing coil, used to detect the current of the bearing coil and transmit to the magnetic bearing controller, in particular to the MCU in the magnetic bearing controller.

[0048] The power amplification circuit of the magnetic bearing system according to the scheme of the present application can ensure the normal operation of the magnetic levitation bearing when the power device fails by detecting the current of the bearing coil, judging the fault point according to the current of the bearing coil and combining the action of the selection switch unit, in particular, the fault point can be automatically checked and reported on the upper computer by opening and closing the analog selection switch, the normal working circuit can be switched to while detecting the fault point, so that the magnetic levitation bearing can work normally during waiting for the technical personnel to solve the fault, and the production efficiency is improved.

[0049] According to the technical scheme of the present application, by arranging the selection switch unit and the two H-bridge circuits in the power amplification circuit of the control system of the magnetic bearing, the two H-bridge circuits are cascaded, the first end of the bearing coil is connected with the selection switch unit, the second end of the bearing coil is connected with the two H-bridge circuits respectively, the two H-bridge circuits are switched to be connected with the bearing coil by controlling the selection switch; in the case of the working magnetic bearing, whether the bearing coil and the two H-bridge circuits of the magnetic bearing system appear faults and the fault points are determined according to the current of the bearing coil, and the two H-bridge circuits are switched to make the magnetic bearing work normally when the faults appear; thereby, by arranging the power amplification branches redundantly in the power amplification circuit of the control system of the magnetic bearing, whether the magnetic bearing system appears faults and the fault points are located according to the current of the bearing coil and combining the action of the selection switch unit, and the power amplification branches are switched to make the magnetic bearing work normally when the power device appears faults, not only the fault points can be detected time-savingly and labor-savingly, but also the normal work of the magnetic bearing system can be ensured to ensure the reliability of the magnetic bearing system.

[0050] According to the embodiments of the present application, a magnetic bearing system corresponding to the power amplification device of the magnetic bearing system is also provided. The magnetic bearing system can comprise the power amplification device of the magnetic bearing system described above.

[0051] Since the processing and functions realized by the magnetic bearing system of the present embodiment are basically corresponding to the embodiments, principles and examples of the device, the descriptions of the present embodiment which are not described in detail can be referred to the related descriptions in the foregoing embodiments, which will not be described here.

[0052] According to the embodiments of the present application, a magnetic bearing system corresponding to the power amplification device of the magnetic bearing system is also provided. The magnetic bearing system can comprise the power amplification device of the magnetic bearing system described above. Figure 5A flowchart of an embodiment of the method of the present application is shown. The fault detection method of the magnetic bearing system can include steps S110 to S140.

[0053] At step S110, assuming that the current H-bridge circuit is the first H-bridge circuit, the current of the bearing coil (e.g., the current I of the bearing coil) is obtained when the first H-bridge circuit is connected to the bearing coil. When the first H-bridge circuit is connected to the bearing coil, the control terminal of the second switch is connected to the first connection terminal of the second switch so that the first PWM signal output by the magnetic bearing controller can be input to the control terminal of the first power device, and the control terminal of the first switch is connected to the first connection terminal of the second switch so that the second connection terminal of the first power device is connected to the first end of the bearing coil. When the first H-bridge circuit is connected to the bearing coil, the magnetic bearing controller outputs the first PWM signal and the second PWM signal to enable the first H-bridge circuit to supply power to the bearing coil and enable the magnetic bearing to operate.

[0054] At step S120, based on the current of the bearing coil, the magnetic bearing system is determined to be faulty by controlling the selected switch unit. The fault of the magnetic bearing system includes at least one of the following: a fault of the bearing coil and a fault of the power device in the first H-bridge circuit.

[0055] At step S130, if it is determined that the bearing coil is faulty, the magnetic bearing is controlled to stop operating, specifically, the shaft of the magnetic bearing is controlled to stop floating.

[0056] At step S140, if it is determined that the power device in the first H-bridge circuit is faulty, the selected switch unit is controlled to connect the second H-bridge circuit to the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to operate. When the second H-bridge circuit is connected to the bearing coil, the control terminal of the second switch is connected to the second connection terminal of the second switch so that the first PWM signal output by the magnetic bearing controller can be input to the control terminal of the third power device, and the control terminal of the first switch is connected to the second connection terminal of the second switch so that the second connection terminal of the third power device is connected to the first end of the bearing coil. When the second H-bridge circuit is connected to the bearing coil, the magnetic bearing controller outputs the first PWM signal and the third PWM signal to enable the second H-bridge circuit to supply power to the bearing coil and enable the magnetic bearing to continue operating.

[0057] The scheme of the application, by setting the first H-bridge circuit, the second H-bridge circuit, and the selection switch unit, the current of the bearing coil is detected by the current sensor, the fault of the magnetic bearing system and the power amplifier circuit thereof can be automatically detected according to the current of the bearing coil and the fault point is reported by the upper computer, the normal working circuit is switched to at the same time of detecting the fault, the fault point can be avoided when the power device fails, and the stable work is continued, not only the fault point can be detected with time and labor saving, but also the normal work of the magnetic bearing system is ensured to ensure the reliability of the magnetic bearing system.

[0058] In some embodiments, the power device in the first H-bridge circuit includes a first power device and a second power device, the power device in the second H-bridge circuit includes a third power device and a fourth power device; the fault of the power device in the first H-bridge circuit includes at least one of the following: the fault of the first power device, the fault of the second power device; the selection switch unit includes a first switch and a second switch. In step S120, whether the magnetic bearing system fails is determined according to the current of the bearing coil and by controlling the selection switch unit, including: a first process of determining whether the magnetic bearing system fails.

[0059] The following will be described in detail with reference to the accompanying drawings. Figure 6 The first process of determining whether the magnetic bearing system fails in the method of the application is further illustrated by an embodiment flowchart of the first process of determining whether the magnetic bearing system fails in step S140, including: steps S210 to S240.

[0060] In step S210, whether the current of the bearing coil is greater than the set maximum current is determined for the first time in the current control period; wherein the set maximum current is, for example, the maximum value Imax of the current of the bearing coil.

[0061] In step S220, if it is determined for the first time in the current control period that the current of the bearing coil is greater than the set maximum current, the second switch in the selection switch unit is controlled to act, so as to stop sending the first PWM signal to the control end of the first power device in the first H-bridge circuit, and send the first PWM signal to the control end of the third power device in the second H-bridge circuit, and then the current of the bearing coil is determined again whether it is greater than the set maximum current.

[0062] If the first power device such as switch S1 is broken at this time, the short-circuit state is equivalent to a wire, and the first PWM signal cannot control the turn-on and turn-off of the first power device such as switch S1, so the second switch in the selection switch unit needs to be controlled to stop sending the first PWM signal to the control end of the first power device in the first H-bridge circuit and send the first PWM signal to the control end of the third power device in the second H-bridge circuit, and then the current of the bearing coil is determined again.

[0063] In step S230, if it is determined again in the current control period that the current of the bearing coil is greater than the set maximum current, it is determined that the first power device is broken, a prompt message that the first power device is broken is initiated, and then in the case that the second switch in the selection switch unit has been actuated, the first switch in the selection switch unit is controlled to switch from the state that the first power device in the first H-bridge circuit is connected with the bearing coil to the state that the third power device in the second H-bridge circuit is connected with the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil through the third power device and the fourth power device in the second H-bridge circuit, a third PWM signal is sent, the third PWM signal outputs the same PWM wave as the second PWM signal, and the magnetic bearing continues to work.

[0064] If the first power device such as switch S1 is broken, the first switch such as analog selection switch 1 in the selection switch unit can be switched in the case that the second switch such as analog selection switch 2 in the selection switch unit has been switched, so that the current path becomes VCC-switch S3-switch S4, and the magnetic bearing can normally operate.

[0065] In step S240, if it is determined again in the current control period that the current of the bearing coil is less than or equal to the set maximum current, it is determined that the second power device in the first H-bridge circuit is broken, a prompt message that the second power device is broken is initiated, and then the first switch in the selection switch unit is controlled to switch from the state that the first power device in the first H-bridge circuit is connected with the bearing coil to the state that the third power device in the second H-bridge circuit is connected with the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil, a third PWM signal is sent, the third PWM signal outputs the same PWM wave as the second PWM signal, and the magnetic bearing continues to work.

[0066] The scheme further proposes a fault detection scheme for a magnetic bearing system and a power amplification circuit thereof, which comprises fault judgment control logic and a switching circuit.Figure 4 The logic diagram for fault judgment control of an embodiment of the fault detection method of the power amplification circuit of the magnetic bearing system of the present application. As shown in the figure, the fault detection method of the power amplification circuit of the magnetic bearing system comprises: Figure 4

[0067] Step 1, first set the maximum value of the current of the bearing coil Imax, collect the current signal of the bearing coil through the current sensor, record it as the current I of the bearing coil, and then execute Step 2.

[0068] Step 2, judge whether the current I of the bearing coil is greater than Imax: if yes, execute Step 2, otherwise execute Step 4.

[0069] Step 2, when the current I of the bearing coil is greater than Imax, the analog selection switch 2 is actuated, the first PWM signal of the switching tube is converted to control the switching tube , and then continue to judge whether the current I of the bearing coil is greater than Imax: if yes, report the breakdown of the switching tube and execute Step 3, otherwise report the breakdown of the switching tube and execute Step 3.

[0070] In Step 2, by default, the control end of the analog selection switch 2 is connected to the first connection end of the analog selection switch 2, and the first PWM signal controls the switching tube ; the magnetic bearing normally works under the control of the first PWM signal and the second PWM signal. In the case of actuation of the analog selection switch 2, the control end of the analog selection switch 2 is connected to the second connection end of the analog selection switch 2, and the first PWM signal controls the switching tube .

[0071] Step 3, actuate the analog selection switch 1 to connect the second end of the bearing coil to the source of the switching tube , and control the third PWM signal to work, so that the magnetic bearing normally works, i.e. the shaft is normally suspended.

[0072] In Step 3, by default, the first connection end of the analog selection switch 1 is connected to the source of the switching tube , and the control end of the analog selection switch 1 is connected to the first connection end of the analog selection switch 1, i.e. the first end of the bearing coil connected to the control end of the analog selection switch 1 is connected to the source of the switching tube , and the magnetic bearing works under the switching tube , the switching tube , the diode , and the diode ​The magnetic bearing is normally operated under the control of the first PWM signal and the second PWM signal. In the case of the action of the analog selection switch 1, the second connection end of the analog selection switch 1 is connected with the source of the switch tube , the control end of the analog selection switch 1 is connected with the second connection end of the analog selection switch 1, that is, the first end of the bearing coil connected with the control end of the analog selection switch 1 is connected with the source of the switch tube , the switch tube , the diode , the diode constitutes another H-bridge circuit, and the magnetic bearing is normally operated under the control of the first PWM signal and the third PWM signal.

[0073] According to the current of the bearing coil, the selection switch unit is controlled to determine whether the magnetic bearing system fails, the fault point is automatically checked by the opening and closing of the analog selection switch, and the fault point is reported on the upper computer, the fault point is detected, and the circuit that can normally work is switched to, so that the magnetic levitation bearing can normally work during the period of waiting for the technical personnel to solve the fault, and the production efficiency is improved.

[0074] In some embodiments, the step S120 of determining whether the magnetic bearing system fails according to the current of the bearing coil and in combination with the control of the selection switch unit further includes a second process of determining whether the magnetic bearing system fails.

[0075] The second process of determining whether the magnetic bearing system fails in the method of the application will be further described below with reference to the embodiment flowchart of the second process of determining whether the magnetic bearing system fails in the method of the application shown in Figure 7 .

[0076] In step S310, after it is determined for the first time in the current control period that the current of the bearing coil is greater than the set maximum current, if it is determined for the first time that the current of the bearing coil is less than or equal to the set maximum current, it is determined for the first time in the current control period whether the current of the bearing coil is equal to 0.

[0077] In step S320, if it is determined for the first time that the current of the bearing coil is not equal to 0 in the current control period, it is determined that neither the bearing coil nor the power device in the first H-bridge circuit fails, the first H-bridge circuit is still used to supply power to the bearing coil, and the magnetic bearing continues to work.

[0078] Step S330, if the first determination of the current of the bearing coil is equal to 0 in the current control cycle, a third PWM signal is sent in the current control cycle, the third PWM signal outputs the same PWM wave as the second PWM signal to control the fourth power device in the second H-bridge circuit to be turned on, and then the second determination of whether the current of the bearing coil is equal to 0 is performed.

[0079] The third PWM signal, such as PWM3, controls the fourth power device, such as the switch tube S4, to be turned on, at which time the path changes from the initial VCC-switch tube S1-bearings coil-switch tube S2 to two paths VCC-switch tube S1-bearings coil-switch tube S2 (switch tube S4), specifically: VCC-switch tube S1-bearings coil-switch tube S2, VCC-switch tube S1-bearings coil-switch tube S4. Turning on the switch tube S4 increases a path and better determines subsequent failures.

[0080] Step S340, if the second determination of the current of the bearing coil is equal to 0 in the current control cycle, the first switch and the second switch in the selection switch unit are controlled to act at the same time to connect the first H-bridge circuit to the bearing coil and switch to connect the second H-bridge circuit to the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil, and then the determination of whether the power device in the first H-bridge circuit and the bearing coil fails is continued.

[0081] If the current of the bearing coil is still 0 in the case of the two paths VCC-switch tube S1-bearings coil-switch tube S2 (switch tube S4), the first switch, such as analog selection switch 1, and the second switch, such as analog selection switch 2, in the selection switch unit are controlled to act at the same time, which can change the path to VCC-switch tube S3-bearings coil-switch tube S4. If there is no current in the bearing coil in any path, it can be determined that the bearing coil fails.

[0082] Step S350, if the second determination of the current of the bearing coil is not equal to 0 in the current control cycle, it is determined that the second power device has an open circuit failure, a prompt message that the second power device has an open circuit failure is initiated, and then the first switch and the second switch in the selection switch unit are controlled to act at the same time to connect the first H-bridge circuit to the bearing coil and switch to connect the second H-bridge circuit to the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil, and then the determination of whether the power device in the first H-bridge circuit and the bearing coil fails is continued.

[0083] Specifically, as shown in Figure 4 the fault detection method of the power amplification circuit of the magnetic bearing system further comprises:

[0084] Step 4, when the current I of the bearing coil is less than or equal to Imax, it is determined whether the current I of the bearing coil is equal to 0; if yes, step 5 is executed, otherwise the magnetic bearing is controlled to work normally.

[0085] Step 5, the third PWM signal is controlled to output the same PWM wave as the second PWM signal to control the on-off of the switch tube , and then it is determined again whether the current I of the bearing coil is equal to 0; if yes, step 6 is executed, otherwise an open circuit fault of the switch tube is reported.

[0086] Step 6, the analog selection switch 1 and the analog selection switch 2 are controlled to act simultaneously, and then it is determined again whether the current I of the bearing coil is equal to 0.

[0087] The scheme of the application can ensure the normal operation of the magnetic suspension bearing when the power device fails by detecting the current of the bearing coil, determining the fault point according to the current of the bearing coil and the action of the selection switch unit, specifically, the fault point can be automatically checked by the opening and closing of the analog selection switch and reported on the upper computer, the normal working circuit can be switched to when the fault point is detected, so that the magnetic suspension bearing can work normally during the period of waiting for the technical personnel to solve the fault, and the production efficiency is improved.

[0088] In some embodiments, the specific process of determining whether the power device in the bearing coil and the first H-bridge circuit fails in the current control cycle in step S350 is described in the following example.

[0089] The following embodiment flowchart of the method of the application shown in Figure 8 further illustrates the wavelet packet analysis process of the online monitoring of step S350, including steps S410 to S430.

[0090] Step S410, the current of the bearing coil is determined for the third time in the current control cycle.

[0091] Step S420, if the current of the bearing coil is determined for the third time not to be equal to 0, it is determined that the bearing coil has an open circuit fault, and then the shaft of the magnetic bearing is controlled to stop floating.

[0092] Step S430, in the current control period, if the third time the current of the bearing coil is determined to be equal to 0, it is determined that the first power device has an open circuit fault, a prompt message that the first power device has an open circuit fault is initiated, and then in the case that the third PWM signal has been outputted to make the third PWM signal output the same PWM wave as the second PWM signal, and the second H-bridge circuit has been switched to be connected with the bearing coil to make the second H-bridge circuit supply power to the bearing coil, the magnetic bearing continues to work.

[0093] Specifically, as shown in Figure 4 the fault detection method of the power amplification circuit of the magnetic bearing system further comprises: in step 6, the bearing coil current I = 0 is re-judged again: if yes, the bearing coil open circuit fault is reported, and the shaft fault is controlled to stop floating, otherwise the switch tube open circuit fault is reported, and the shaft is normally suspended, that is, the magnetic bearing is normally controlled under the first PWM signal and the third PWM signal. , the switch tube , the diode , the diode constitute another H-bridge circuit, and the magnetic bearing normally works under the control of the first PWM signal and the third PWM signal.

[0094] The scheme of the present application can automatically check the fault point by simulating the opening and closing of the selection switch, and report the fault point on the upper computer. The fault point can be detected while switching to the normally working circuit, so that the magnetic suspension bearing can normally work during the period waiting for the technical personnel to solve the fault, and the production efficiency is improved.

[0095] In some embodiments, the power devices in the first H-bridge circuit include a first power device and a second power device, the power devices in the second H-bridge circuit include a third power device and a fourth power device; the fault of the power devices in the first H-bridge circuit includes at least one of the following: a fault of the first power device, a fault of the second power device; the selection switch unit includes a first switch and a second switch. In step S140, if it is determined that the power devices in the first H-bridge circuit have a fault, the selection switch unit is controlled to connect the second H-bridge circuit with the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to work, including at least one of the following, that is, at least one of any one of the following control situations: a first control situation and a second control situation.

[0096] The first control situation is: if it is determined that the first power device has breakdown failure, or it is determined that the second power device in the first H-bridge circuit has breakdown failure, the first switch in the selection switch unit is controlled to switch from the state that the first power device in the first H-bridge circuit is connected with the bearing coil to the state that the third power device in the second H-bridge circuit is connected with the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil, a third PWM signal is sent, and the third PWM signal output is the same PWM wave as the second PWM signal, so that the magnetic bearing continues to work.

[0097] Specifically, as shown in the figure, Figure 4 The fault detection method of the power amplification circuit of the magnetic bearing system further includes: in steps 2 and 3, when the current I of the bearing coil is greater than Imax, the simulation selection switch 2 is actuated, the first PWM signal of the switch tube is converted to the control of the switch tube At this time, if the current I of the bearing coil continues to be greater than Imax, it is judged that the switch tube has breakdown; if the current I of the bearing coil decreases and is less than Imax, it is judged that the switch tube has breakdown; regardless of which fault, the simulation selection switch 1 is actuated, the third PWM signal output is the same PWM wave as the second PWM signal, and the three-level working state is completed by the switch tube , the switch tube and the diode , the diode , and the magnetic levitation bearing works normally.

[0098] The simulation selection switch 2 is actuated to determine the fault condition of the switch tube S1: if the simulation selection switch 2 is actuated and the switch tube S1 can still be turned on, that is, I>Imax, it is proved that the switch tube S1 has short-circuit breakdown. The simulation selection switch 1 is actuated to disconnect the path of the switch tube S1. In addition, the PWM wave output by the PWM signal 1 is the same as the PWM signal 2 or 3, because the upper and lower tubes cannot be directly connected, otherwise they will be short-circuited, and there must be a dead zone. Under the theoretical condition, the PWM wave output by the PWM signal 1 is the complementary wave of the waveforms output by the PWM signal 2 or 3.

[0099] The second control case: if it is determined that the first power device has an open circuit fault, or it is determined that the second power device has an open circuit fault, the first switch and the second switch in the selection switch unit are controlled to act simultaneously in the case that a third PWM signal is sent to make the third PWM signal output the same PWM wave as the second PWM signal, so as to connect the first H bridge circuit with the bearing coil, switch to the second H bridge circuit connected with the bearing coil, and make the second H bridge circuit supply power to the bearing coil, so as to make the magnetic bearing continue to work.

[0100] Specifically, as shown in the figure, Figure 4 the fault detection method of the power amplification circuit of the magnetic bearing system further comprises: in steps 4 to 6, if the current I of the bearing coil is less than Imax, it is judged whether the current I of the bearing coil is 0, if the current I of the bearing coil is not 0, the magnetic levitation bearing is in a normal working state without fault; if the current I of the bearing coil is 0, the third PWM signal is output to make the third PWM signal output the same PWM wave as the second PWM signal, and the on-off of the switching tube is controlled, if the current I of the bearing coil is not 0 at this time, it is judged that the switching tube has an open circuit fault; if the current I of the bearing coil is still 0 at this time, the analog selection switch 1 and the analog selection switch 2 act simultaneously, and then it is judged whether the current I of the bearing coil is 0, if the current I of the bearing coil is not 0, it is judged that the switching tube has an open circuit fault, and the three-level working state is completed by the switching tube , the switching tube and the diode , the diode , and the magnetic bearing normally operates, if the current I of the switching tube is 0, it is judged that the coil has an open circuit fault, and the magnetic levitation bearing is protected to stop floating. In this case, the third PWM signal is first output to make the third PWM signal output the same PWM wave as the second PWM signal, and then the analog selection switch 1 and the analog selection switch 2 act simultaneously, so as to switch the redundant circuit and judge whether the fault is an open circuit of the bearing coil. By opening each switch in turn, the fault device can be effectively located.

[0101] The scheme of the application can make the magnetic levitation bearing control system automatically report the fault point by detecting the current of the bearing coil and judging the fault point according to the current of the bearing coil and the action of the selection switch unit, and can change the circuit connection for normal operation when detecting the power device fault, such as adopting a redundant design structure for the power amplification circuit, so that when one way of the power amplification circuit is detected to be damaged, the other way can be replaced, the troubleshooting time and manpower are saved, and the production efficiency is improved.

[0102] Since the processing and functions realized by the method of the embodiment are basically corresponding to the foregoing embodiments, principles and examples of the magnetic bearing system, the description of the embodiment which is not elaborated can be referred to the related description in the foregoing embodiments, which will not be described here.

[0103] 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.

[0104] The above only describes the embodiments of the present application and is not used to limit the present application. The present application can have various modifications and changes for the person skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A power amplifier device for a magnetic bearing system, characterized by The magnetic bearing system has a magnetic bearing and a magnetic bearing control system; the magnetic bearing has a bearing coil; the magnetic bearing control system has a power amplifier device and a magnetic bearing controller; the power amplifier device of the magnetic bearing system comprises: a first H-bridge circuit, a second H-bridge circuit and a selection switch unit; wherein, The first H-bridge circuit and the second H-bridge circuit are cascaded, and the first H-bridge circuit and the second H-bridge circuit are redundantly arranged as power amplifier branches; The first end of the bearing coil is connected with the selection switch unit, and the second end of the bearing coil is connected with the first H-bridge circuit and the second H-bridge circuit respectively; The selection switch unit is capable of switchingly connecting the bearing coil with any one of the first H-bridge circuit and the second H-bridge circuit; one of the first H-bridge circuit and the second H-bridge circuit currently connected with the bearing coil is recorded as a current H-bridge circuit; The magnetic bearing controller is used for determining whether the magnetic bearing system has a fault according to the current of the bearing coil and in combination with controlling the selection switch unit; the fault of the magnetic bearing system comprises at least one of the following: a fault of the bearing coil and a fault of a power device in the current H-bridge circuit; and If it is determined that the bearing coil has a fault, the magnetic bearing is controlled to stop working; If it is determined that the power device in the current H-bridge circuit has a fault, the selection switch unit is controlled to connect the other H-bridge circuit of the first H-bridge circuit and the second H-bridge circuit with the bearing coil to supply power for the bearing coil, so that the magnetic bearing continues to work; The selection switch unit comprises: a first switch and a second switch; the first H-bridge circuit comprises: a first power device; the second H-bridge circuit comprises: a third power device; The control end of the first switch is used for receiving a first PWM signal sent by the magnetic bearing controller; the first connection end of the first switch is connected with the control end of the first power device; the first connection end of the first power device is connected with a direct current power supply; the second connection end of the first switch is connected with the control end of the third power device; the first connection end of the third power device is connected with the direct current power supply; The control end of the second switch is connected with the first end of the bearing coil; the first connection end of the second switch is connected with the second connection end of the first power device; and the second connection end of the second switch is connected with the second connection end of the third power device.

2. The power amplifier device of a magnetic bearing system according to claim 1, wherein, The first H-bridge circuit further comprises: a second power device; the second H-bridge circuit further comprises: a fourth power device; wherein, The control end of the second power device is used for receiving a second PWM signal sent by the magnetic bearing controller; the first connection end of the second power device is connected with the second end of the bearing coil; and the second connection end of the second power device is grounded. A control end of the fourth power device is configured to receive a third PWM signal sent by the magnetic bearing controller; a first connection end of the fourth power device is connected to the second end of the bearing coil; and a second connection end of the fourth power device is grounded.

3. The power amplifier device of the magnetic bearing system according to claim 2, wherein, The first H-bridge circuit further comprises a first diode and a second diode, and the second H-bridge circuit further comprises a third diode and a fourth diode. The cathode of the first diode is connected to a DC power supply, and the anode of the first diode is connected to the second end of the bearing coil; the cathode of the second diode is connected to the first end of the bearing coil, and the anode of the second diode is grounded; The cathode of the third diode is connected to the first end of the bearing coil, and the anode of the third diode is grounded; the cathode of the fourth diode is connected to a DC power supply, and the anode of the fourth diode is connected to the second end of the bearing coil.

4. The power amplifier arrangement of any one of claims 1 to 3, characterized in that Further comprising: A current detection unit; wherein The current detection unit is arranged at the second end of the bearing coil, configured to detect the current of the bearing coil and transmit to the magnetic bearing controller.

5. A magnetic bearing system characterized by, Comprise: The power amplification device of the magnetic bearing system according to any one of claims 1 to 4.

6. A method of fault detection for a magnetic bearing system as claimed in claim 5, characterized in that, Comprise: The current H-bridge circuit is the first H-bridge circuit, and the current of the bearing coil is obtained when the first H-bridge circuit is connected to the bearing coil; According to the current of the bearing coil, the selection switch unit is controlled to determine whether the magnetic bearing system fails; the failure of the magnetic bearing system includes at least one of the following: the failure of the bearing coil, the failure of the power device in the first H-bridge circuit; and If it is determined that the bearing coil fails, the magnetic bearing is controlled to stop working; If it is determined that the power device in the first H-bridge circuit fails, the selection switch unit is controlled to connect the second H-bridge circuit to the bearing coil to supply power to the bearing coil, so that the magnetic bearing continues to work. According to the current of the bearing coil, the selection switch unit is controlled to determine whether the magnetic bearing system fails, comprising:

7. The magnetic bearing system fault detection method of claim 6, wherein In the current control cycle, it is firstly determined whether the current of the bearing coil is greater than the set maximum current; If it is firstly determined that the current of the bearing coil is greater than the set maximum current, the second switch in the selection switch unit is controlled to stop sending the first PWM signal to the control end of the first power device in the first H-bridge circuit and to send the first PWM signal to the control end of the third power device in the second H-bridge circuit, and then it is determined again whether the current of the bearing coil is greater than the set maximum current; If it is determined again that the current of the bearing coil is greater than the set maximum current, it is determined that the first power device fails, and a prompt message of the breakdown failure of the first power device is initiated; If it is determined again that the current of the bearing coil is less than or equal to the set maximum current, it is determined that the second power device in the first H-bridge circuit fails, and a prompt message of the breakdown failure of the second power device is initiated. ​ 8. The magnetic bearing system fault detection method of claim 7, wherein, The method further comprises: If the current of the bearing coil is determined to be less than or equal to the set maximum current for the first time, it is determined whether the current of the bearing coil is equal to 0 for the first time; If the current of the bearing coil is determined not to be equal to 0 for the first time, it is determined that neither the bearing coil nor the power device in the first H-bridge circuit has a fault, and the first H-bridge circuit is still controlled to supply power to the bearing coil, so that the magnetic bearing continues to work; If the current of the bearing coil is determined to be equal to 0 for the first time, a third PWM signal is sent, and the third PWM signal outputs a PWM wave identical to the second PWM signal to control the fourth power device in the second H-bridge circuit to be turned on, and then it is determined whether the current of the bearing coil is equal to 0 for the second time; If the current of the bearing coil is determined to be equal to 0 for the second time, the first switch and the second switch in the selection switch unit are controlled to act simultaneously, so that the first H-bridge circuit is connected to the bearing coil, the second H-bridge circuit is switched to be connected to the bearing coil, the second H-bridge circuit is controlled to supply power to the bearing coil, and then it is determined whether the bearing coil and the power device in the first H-bridge circuit have a fault; If the current of the bearing coil is determined not to be equal to 0 for the second time, it is determined that the second power device has an open-circuit fault, a prompt message that the second power device has an open-circuit fault is initiated, and then it is determined whether the bearing coil and the power device in the first H-bridge circuit have a fault.

9. The magnetic bearing system fault detection method of claim 8, wherein, The method further comprises: The current of the bearing coil is determined for the third time whether the current of the bearing coil is equal to 0; If the current of the bearing coil is determined not to be equal to 0 for the third time, it is determined that the bearing coil has an open-circuit fault; If the current of the bearing coil is determined to be equal to 0 for the third time, it is determined that the first power device has an open-circuit fault, and a prompt message that the first power device has an open-circuit fault is initiated.

10. The magnetic bearing system fault detection method according to any one of claims 6 to 9, characterized by, If it is determined that the power device in the first H-bridge circuit has a fault, the selection switch unit is controlled, the second H-bridge circuit is connected to the bearing coil, power is supplied to the bearing coil, and the magnetic bearing continues to work, which comprises at least one of the following: In the case that the first H-bridge circuit further comprises a second power device, if it is determined that the first power device has breakdown failure, or it is determined that the second power device in the first H-bridge circuit has breakdown failure, the first switch in the selection switch unit is controlled to switch from the state that the first power device in the first H-bridge circuit is connected with the bearing coil to the state that the third power device in the second H-bridge circuit is connected with the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil, a third PWM signal is sent, and the third PWM signal output is the same PWM wave as the second PWM signal, so that the magnetic bearing continues to work; In the case that the first H-bridge circuit further comprises a second power device, if it is determined that the first power device has open circuit failure, or it is determined that the second power device has open circuit failure, in the case that the third PWM signal is sent to make the third PWM signal output the same PWM wave as the second PWM signal, the first switch and the second switch in the selection switch unit are controlled to simultaneously act, so as to switch from the state that the first H-bridge circuit is connected with the bearing coil to the state that the second H-bridge circuit is connected with the bearing coil, so that the second H-bridge circuit supplies power to the bearing coil, so as to make the magnetic bearing continue to work.

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