A Space Vector Based Switching Power Amplifier for Pure Electromagnetic Magnetic Bearing System

Abstract

The invention relates to a space vector-based switching power amplifier for a purely-electromagnetic magnetic bearing system. The space vector-based switching power amplifier is a device for carrying out active control on current in a purely-electromagnetic magnetic bearing coil and mainly comprises a controller, an isolating driver circuit, a four-bridge-arm power main circuit, a current feedback detection circuit, a signal conditioning circuit and a signal filter circuit. According to the digital switching power amplifier, the controller is used for calculating an error between a current sampling value and an expected current value and then carrying out PWM (Pulse-Width Modulation) on the basis of space vector, and then on-off of a power switching tube in the four-bridge-arm power main circuit is controlled by the isolating driver circuit through the modulated PWM signal, and therefore the purpose of controlling the current of the magnetic bearing coil is achieved. The digital switching power amplifier disclosed by the invention is suitable for the purely-electromagnetic magnetic bearing control system and has the advantages of reducing the quantity of the power switching tubes and the amplitude of output ripple current and decreasing the loss of an electromagnetic bearing.

Description

technical field [0001] The invention relates to a switching power amplifier, which is a switching power amplifier based on a space vector pure electromagnetic bearing system, and is used for actively controlling the output current of a pure electromagnetic bearing coil. Background technique [0002] Due to the use of magnetic suspension bearings instead of traditional mechanical bearings, high-speed magnetic levitation motors have the advantages of high speed, no friction, no lubrication, high energy density, small size, etc., and have broad application prospects. As the actuator of the magnetic bearing control system of the high-speed magnetic levitation motor, the power amplifier consumes the most energy. One of the main purposes of power amplifier design is to reduce the energy loss of the power amplifier, improve integration, and increase reliability. [0003] In order to improve the efficiency of the power amplifier, the magnetic bearing control system of the high-speed...

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Problems solved by technology

[0004] In the Chinese patent "ZL200510012131.2" disclosed "a low-ripple switching power amplifier for permanent magnet bias electromagnetic bearings", analog devices are used to realize the function of three-level PWM pulse width modulation, which reduces the ripple loss; however, the power amplifier built with analog devices has a large loss and a large volume. At the same time, if you want to change the PWM modulation method, you must perform hardware adjustments, which is inconvenient to use.

[0005] In the Chinese patent "200610114390.0" disclosed "a switching power amplifier for magnetic bearing system of magnetic levitation flywheel", FPGA+DSP is used as the controller, and the three-state PWM modulation method is adopted, which has strong data processing ability and small current ripple; However, a non-inductive power resistor needs to be connected in series between the sources of the two power switch tubes of the lower bridge and the reference ground, and the current signal is sampled through FPGA control when the loop continues to flow. The control method is complex and programming is difficult.

[0006] Both of the above two patents adopt a full-bridge structure, and four controllable power switch tubes are required to control one coil, and 40 controllable power switch tubes are required to realize pure electromagnetic magnetic bearing control with 10 coils, resulting in both volume and loss. has increased

[0007] In Zeng Xueming, Xu Longxiang, Liu Zhengxun's article "Research on Electromagnetic Bearing Three-level PWM Power Amplifier", a figure 2 The three-level switching power amplifier with a half-bridge structure shown in the figure only needs two controllable power transistors and two uncontrollable diodes to control one coil, which can overcome the large output current ripple of the two-level PWM pulse width modulation method. However, it can only control one coil. To control a pure electromagnetic magnetic bearing system with 10 coils, 20 controllable power switch tubes are required, and the volume and loss increase.

[0008] In the Chinese patent "200710120705.7" disclosed "A Space Vector Based Switching Power Amplifier for Magnetic Bearing System", the image 3 The shown three-arm structure is used as the main circuit, FPGA+DSP is used as the controller, and the two-dimensional space vector modulation method is used to greatly reduce the current ripple loss, and the middle bridge arm is shared by two magnetic bearing coils, reducing the The number of power switch tubes reduces the volume of the power amplifier circuit; using this structure to control a pure electromagnetic magnetic bearing system with 10 coils requires 30 controllable power switch tubes, and the essence of the structure is still a full-bridge structure. For unidirectional flow pure electromagnetic bearings, the volume and power consumption of the power amplifier circuit are still relatively large

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