Walsh Function Based Position Sensorless Control for Interior Permanent Magnet Motor Drives using Ripple-Current of High-Frequency Triangular-Wave-Carried PWM Inverter

Abstract

This paper proposes the Walsh function based position sensorless drive method of a PM motor by using high-frequency 20[kHz] triangular-wave-carrier PWM inverter ripple-current. The proposed method uses the Walsh harmonic of PWM inverter ripple-current to estimate the motor rotor position. By using the high frequency switching ripple-current, the period of the rotor position estimation has been decreased and improves the step response of PM motor. The Walsh function makes it possible to use a definite-integrator as the Walsh harmonic detector that can separate the small ripple-current signal from the motor drive-current signal. The Walsh harmonic detector circuit consists of less parts than that of the Fourier harmonic detector circuit. The validity of the proposed method was clarified by several experimental results.