Position Estimation of a Matrix-Converter-Fed AC PM Machine From Zero to High Speed Using PWM Excitation

This paper describes a sensorless position estimation method for a permanent-magnet (PM) motor fed from a three-phase matrix converter using only its space-vector pulsewidth-modulation (SVPWM) sequence. The scheme employs measurements of dii/dt of the motor line currents to construct orthogonal ldquoresolverlikerdquo position signals. In principle, the SVPWM waveforms provide sufficient excitation to extract the position signal from the motor current. However, in order to improve the signal-to-noise ratio of the di/dt signals, a small modification to the SVPWM is required. Sensorless control of the PM synchronous motor at zero and high speeds is demonstrated experimentally. The use of alternative input voltage vectors is also investigated to reduce the current ripple.