Magnetic suspension power drive and fault detection system

Abstract

The invention discloses a magnetic suspension power drive and fault detection system which comprises a displacement detection module, a microcontroller, an optocoupler gate drive module, an IPM module, a fault protection module, a current detection module, a power module, a bearing coil of magnetic suspension to be controlled and a rotor. The input end of the displacement detection module collects the detected rotor position in real time, and the output end is connected with the microcontroller; the microcontroller is provided with a PWM signal output end which is connected with the input end of the optocoupler gate driving module; the output end of the optocoupler gate driving module is connected with the input end of the IPM module; the input end of the fault protection module is connected with a fault output pin of the IPM module, and the output end of the fault protection module is connected with an enabling pin of the microcontroller; the IPM module outputs control current to generate electromagnetic force in a bearing coil so as to drive a rotor; and the current detection module is connected in series in a circuit in which the output terminal of the IPM module is connected with the bearing coil. The failure rate of magnetic suspension control is reduced, and the efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of magnetic levitation control technology, and in particular to a magnetic levitation power drive and fault detection system. Background Technology

[0002] Magnetic levitation technology is a technique that uses magnetic force to overcome gravity and levitate an object. A magnetic levitation system consists of four parts: a rotor, sensors, a controller, and actuators. Assuming the rotor is at a reference position and experiences a downward disturbance, it will deviate from its reference position. The sensor detects this displacement, and the microprocessor in the controller converts this displacement into a control signal. A power amplifier then converts this control signal into a control current. This control current generates magnetic force in the actuator magnets, thereby driving the rotor back to its original equilibrium position. Therefore, regardless of whether the rotor experiences a downward or upward disturbance, it can always maintain a stable equilibrium state.

[0003] Magnetic levitation technology is widely used in applications such as high-speed centrifuges (e.g., natural gas compressors, air separation equipment) and high-speed motors. Its core technologies include power drive technology, fault diagnosis and fault-tolerant control, and displacement sensor design. However, it currently suffers from the following technical shortcomings:

[0004] Low power drive efficiency: Traditional linear power amplifiers have an efficiency of less than 40% and generate significant heat.

[0005] Electromagnetic interference sensitive: The dv / dt and di / dt of the switching power supply cause serious interference to the control circuit;

[0006] Inadequate fault protection: slow response of overcurrent and overvoltage protection, lack of fault prediction mechanism;

[0007] Insufficient accuracy: Insufficient accuracy in displacement detection leads to errors and affects performance. Summary of the Invention

[0008] Purpose of the invention: The purpose of this invention is to provide a magnetic levitation power drive and fault detection system, which improves the above-mentioned technical defects, increases power drive efficiency, and improves fault detection.

[0009] Technical solution: A magnetic levitation power drive and fault detection system, including a displacement detection module, a microcontroller, an optocoupler gate drive module, an IPM module, a fault protection module, a current detection module, a power supply module, and a bearing coil and rotor to be controlled for magnetic levitation;

[0010] The input of the displacement detection module acquires the detected rotor position in real time, and the output is connected to a microcontroller.

[0011] The microcontroller has a PWM signal output terminal, which is connected to the input terminal of the optocoupler gate drive module; the output terminal of the optocoupler gate drive module is connected to the input terminal of the IPM module.

[0012] The input terminal of the fault protection module is connected to the fault output pin of the IPM module, and the output terminal is connected to the enable pin of the microcontroller.

[0013] The IPM module outputs a control current that generates an electromagnetic force in the bearing coil, thereby driving the rotor.

[0014] The current detection module is connected in series in the circuit where the output terminal of the IPM module is connected to the bearing coil;

[0015] The power module provides the required voltage level to all modules.

[0016] Furthermore, the rotor position includes five degrees of freedom: two each in the radial (x and y) directions and one in the axial direction. The direction and magnitude of the rotor displacement are detected.

[0017] Furthermore, the displacement detection module includes a displacement sensor, a differential signal amplifier circuit, an analog multiplier, a low-pass filter, a bias circuit, and a single-ended to differential circuit. After conditioning, amplifying, filtering, and biasing the rotor position signal, it is output to the ADC interface of the microcontroller.

[0018] Preferably, the displacement sensor is an eddy current sensor.

[0019] Preferably, the current detection module uses a current sensor, which is connected in series in the circuit where the output terminal of the IPM module is connected to the bearing coil.

[0020] Furthermore, the power supply module includes a rectifier bridge module and a flyback power supply module. The input terminal of the rectifier bridge module receives AC power, and the output terminal is connected to the flyback power supply module. The flyback power supply module outputs multiple DC voltages.

[0021] Beneficial effects: The magnetic levitation power drive and fault detection system of the present invention is protected by a series of overcurrent, overvoltage, and overtemperature protection designs, with an average fault-free time of more than 80,000 hours, thus enhancing reliability; the displacement control accuracy reaches the micron level, thus improving precision; the overall circuit is simplified, and the cost is reduced by 30% compared to the traditional method. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0023] Figure 2 This is the circuit schematic of the power module;

[0024] Figure 3 Here is a flowchart of the displacement detection module;

[0025] Figure 4 This is the circuit schematic of the displacement detection module;

[0026] Figure 5 The circuit schematic for displacement detection excitation signal;

[0027] Figure 6 A power drive flow diagram consisting of an optocoupler gate drive module and an IPM module;

[0028] Figure 7 The circuit schematic is for a power drive consisting of an optocoupler gate drive module and an IPM module. Detailed Implementation

[0029] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0030] A magnetic levitation power drive and fault detection system, as shown in the attached figure. Figure 1 As shown, it includes a displacement detection module, a microcontroller, an optocoupler gate drive module, an IPM module, a fault protection module, a current detection module, a power supply module, and a bearing coil and rotor to be controlled for magnetic levitation.

[0031] The input of the displacement detection module acquires the detected rotor position in real time, and the output is connected to a microcontroller.

[0032] The microcontroller has a PWM signal output terminal, which is connected to the input terminal of the optocoupler gate drive module; the output terminal of the optocoupler gate drive module is connected to the input terminal of the IPM module.

[0033] The input terminal of the fault protection module is connected to the fault output pin of the IPM module, and the output terminal is connected to the enable pin of the microcontroller.

[0034] The IPM module outputs a control current that generates an electromagnetic force in the bearing coil, thereby driving the rotor.

[0035] The current detection module uses a current sensor, which is connected in series in the circuit where the output terminal of the IPM module is connected to the bearing coil;

[0036] The power module provides the required voltage level to all modules.

[0037] The power module provides the required voltage levels for all modules, including the displacement detection module, microcontroller, optocoupler gate drive module, and IPM module. (See attached diagram.) Figure 2As shown, the power supply module includes a rectifier bridge module and a flyback power supply module. The input terminal of the rectifier bridge module receives AC power, and the output terminal is connected to the flyback power supply module. The flyback power supply module outputs multiple DC voltages. The flyback power supply module uses an isolated flyback transformer, combined with a power management chip and linear optocouplers to adjust the duty cycle of the switching devices, achieving a stable output voltage to provide the required voltage signals for each module. For example, it provides the required voltages such as 5V / ±15V / 24V to other modules, which are then converted into 3.3V / 1.2V power supplies by a linear regulator to apply to the microprocessor chip.

[0038] The displacement detection module is used to detect the rotor position. It determines the rotor position through demodulation and sampling of the circuit to prevent position deviation and control rotor levitation. The rotor position includes five degrees of freedom: two each in the radial (x and y) directions and one in the axial direction. It detects changes in rotor position, including the direction and magnitude of displacement.

[0039] Combined with appendix Figure 3 , 4 As shown, the displacement detection module includes a displacement sensor, a differential signal amplifier circuit, an analog multiplier, a low-pass filter, a bias circuit, and a single-ended to differential converter circuit. The rotor position signal acquired by the displacement sensor is conditioned, amplified, filtered, and biased before being output to the microcontroller's ADC interface. The displacement sensor uses an eddy current sensor, which has the advantages of being non-contact, highly accurate, and having a high bandwidth. (See attached diagram) Figure 5 The diagram shows the circuit schematic for displacement detection excitation signal. The displacement sensor outputs a pair of signals in a specific direction, which are then amplified differentially by an instrument and input to an analog multiplier. The analog multiplier performs calculations with the excitation signal to output a DC signal with a low-frequency bias. This DC signal is then passed through an active low-pass filter, biased, and input to a single-ended to differential converter chip before being output to an ADC for sampling. Upper and lower limits are set for the movement position in each direction, serving as displacement protection detection signals transmitted to the inverter input interface to protect the bearings in a timely manner.

[0040] The optocoupler gate drive module and the IPM module constitute the power drive, used to levitate the rotor, and together with current detection fault alarm, achieve stable levitation. (See attached...) Figure 6 , 7 As shown, the optocoupler is used to drive the subsequent integrated IPM module, which is a key component that converts weak control signals into a powerful current capable of driving the electromagnet.

[0041] The microprocessor chip DSP converts the output digital quantity into a precise analog voltage or PWM wave through the optocoupler gate drive module. After passing through a buffer, the output capability is increased to the optocoupler input. The analog voltage signal corresponding to the optocoupler output is input to the IPM module as the input of the power device IPM module. The power device itself forms a current closed loop, which detects the real-time current of the electromagnet coil through a series sampling resistor or Hall sensor. Finally, the integrated circuit inside the module processes and outputs the corresponding load current. At the same time, the series sampling resistor at the load is input to the precision current detection enhanced isolation modulator to detect changes in current magnitude in real time and the fault signals of overcurrent or short circuit in the module's own output, and then generates a self-locking protection to shut down the PWM wave.

[0042] The magnetic levitation power drive and fault detection system of this application simplifies the design of peripheral drive circuits and output filtering compared to switching power amplifiers by using an IPM module. The addition of a precision current detection isolated modulator improves sampling accuracy, and the use of single-ended to differential displacement sampling enhances resolution and accuracy, achieving micron-level displacement precision. Self-locking protection and upper / lower displacement limit protection are added, significantly improving isolation and anti-interference capabilities against output faults. Power circuit efficiency is increased from the traditional 80% to over 90%, improving energy efficiency. A series of overcurrent, overvoltage, and overtemperature protection designs ensure a mean time between failures (MTBF) of over 80,000 hours, enhancing reliability. Displacement control accuracy reaches the micron level, improving precision. The overall circuit is simplified, reducing costs by 30% compared to traditional methods.

Claims

1. A magnetic levitation power drive and fault detection system, characterized in that: It includes a displacement detection module, a microcontroller, an optocoupler gate drive module, an IPM module, a fault protection module, a current detection module, a power supply module, and the bearing coil and rotor to be controlled for magnetic levitation; The input of the displacement detection module acquires the detected rotor position in real time, and the output is connected to a microcontroller. The microcontroller has a PWM signal output terminal, which is connected to the input terminal of the optocoupler gate drive module; the output terminal of the optocoupler gate drive module is connected to the input terminal of the IPM module. The input terminal of the fault protection module is connected to the fault output pin of the IPM module, and the output terminal is connected to the enable pin of the microcontroller. The IPM module outputs a control current that generates an electromagnetic force in the bearing coil, thereby driving the rotor. The current detection module is connected in series in the circuit where the output terminal of the IPM module is connected to the bearing coil; The power module provides the required voltage level to all modules.

2. The magnetic levitation power drive and fault detection system according to claim 1, characterized in that: The rotor position has five degrees of freedom: two each in the radial x and y directions, and one in the axial direction.

3. The magnetic levitation power drive and fault detection system according to claim 1, characterized in that: The displacement detection module includes a displacement sensor, a differential signal amplifier circuit, an analog multiplier, a low-pass filter, a bias circuit, and a single-ended to differential circuit. After conditioning, amplifying, filtering, and biasing the rotor position signal, it is output to the ADC interface of the microcontroller.

4. The magnetic levitation power drive and fault detection system according to claim 3, characterized in that: The displacement sensor uses an eddy current sensor.

5. The magnetic levitation power drive and fault detection system according to claim 1, characterized in that: The current detection module uses a current sensor, which is connected in series in the circuit where the output terminal of the IPM module is connected to the bearing coil.

6. The magnetic levitation power drive and fault detection system according to claim 1, characterized in that: The power supply module includes a rectifier bridge module and a flyback power supply module. The input terminal of the rectifier bridge module receives AC power, and the output terminal is connected to the flyback power supply module. The flyback power supply module outputs multiple DC voltages.

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