Abstract
In position sensorless control based on a high-frequency pulsating voltage injection method, filters are used to complete the extraction of high-frequency response signals for position observation. A finite impulse response (FIR) filter has the advantages of good stability and linear phase. However, the FIR filter designed by using traditional methods has a high order which will cause a large time delay. This paper proposes a low-order FIR filter design method for a high-frequency signal injection method in the permanent magnet linear synchronous motor. Based on the frequency characteristics of the current signal, the requirement that the FIR filter needs to meet were analyzed. According to the amplitude–frequency characteristic of the FIR filter, these requirements were converted into constraint equations. By solving these equations, the coefficient of the FIR filter could be obtained. The simulation and experiment results showed the effectiveness of this low-order FIR filter.
Highlights
Due to the fact of its high efficiency and high-power density, the permanent magnet linear synchronous motor (PMLSM) is used in the drive system of the maglev train
The high-frequency square-wave voltage injection method is based on the saliency of the PMLSM
Equation (1) can be expressed as: In addition, the high-frequency square-wave voltage injection method is used when PMLSM is at low speed, which means speed v is approximately 0
Summary
Due to the fact of its high efficiency and high-power density, the permanent magnet linear synchronous motor (PMLSM) is used in the drive system of the maglev train. All methods are required in order to extract the high-frequency response signal which carries magnetic pole position information from the motor current. This extraction process directly determines the accuracy of the position estimation. When PMLSM is used in the maglev train drive system and the high-frequency square-wave voltage is injected, the current will fluctuate and generate normal force fluctuation. This means that increasing the amplitude of injection voltage will increase the impact on the suspension system. Compared with the filterless estimation system, the amplitude of the injection voltage can be reduced which will increase the voltage utilization [17] and reduce the normal force fluctuation
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