Zero speed position estimation of a matrix converter fed AC PM machine using PWM excitation

This paper describes a sensorless position estimation method of a permanent magnet motor fed from a three-phase matrix converter using only its space vector PWM (SVPWM) sequence. The scheme employs measurements of the di/dt of the motor line currents to construct orthogonal ldquoresolver likerdquo 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 permanent magnet synchronous motor at low and zero speed is demonstrated experimentally. The small input voltage to the matrix converter is also investigated to reduce the current ripple.