Three-dimensional spatial vector based switch power amplifier of magnetic bearing system

Abstract

The invention discloses a three-dimensional spatial vector based switch power amplifier of a magnetic bearing system. The three-dimensional spatial vector based switch power amplifier is a device for actively controlling current in a magnetic bearing coil, and mainly comprises a controller, an isolating driving circuit, a four-leg power main circuit, a current feedback detecting circuit, a signal conditioning circuit and a signal filtering circuit. According to a digital switch power amplifier, after the error of a current sampling value and a current desired value is calculated by using a controller and the real-time dead zone amendment is carried out, the PWM (pulse-width modulation) modulation based on a three-dimensional spatial vector is carried out; and furthermore, the on-off of power switch tubes in the four-leg power main circuit is controlled by using a PWM signal (obtained from the modulation) through the isolating driving circuit, so that the purpose of controlling the current of the magnetic bearing coil is achieved. According to the invention, the digital switch power amplifier which is applicable to the magnetic bearing control system is realized; the number of the power switch tubes and the amplitude of output ripple current are reduced; and the loss of an electromagnetic bearing is reduced.

Description

technical field [0001] The invention relates to a switching power amplifier, which is a switching power amplifier of a magnetic bearing system based on a three-dimensional space vector, and is used for actively controlling the output current of a magnetic 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 ...

AI Technical Summary

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 4 power switch tubes are required to control one coil, and 20 power amplifier tubes are needed to realize the magnetic bearing control of 5 coils, resulting in increased volume and loss

[0007] In the Chinese patent "200710120705.7" disclosed "A Space Vector Based Switching Power Amplifier for Magnetic Bearing System", the figure 2 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; however, the number of switch tubes is still large, and the volume of the power amplifier circuit is still large. If the number of switch tubes and the volume of the power amplifier circuit are to be further reduced, this method will be limited , and this method can only realize vector adjustment in two-dimensional space, and at the same time, it uses sampling resistors for current sampling. When the power supply voltage is high, the isolation effect is weak, the safety is not high, and the anti-interference performance is not strong.

[0008] At the same time, the above patents do not consider the influence of the PWM dead zone on the magnetic bearing voltage. When the dead zone time is large and the modulation frequency is relatively high, the accumulation of voltage difference caused by the dead zone cannot be ignored.

Images