Control of three phase inverter for AC motor drive with small DC-link capacitor fed by single phase AC source

摘要

If a small DC-link capacitor is used in the DC-link fed by single phase AC source, the DC-link voltage fluctuates severely with twice of the source frequency. To handle this fluctuation, the concept of ‘average voltage constraint’ is proposed in this study. On the basis of the concept, a flux weakening scheme generating d-axis current reference (idsr*) for Interior Permanent Magnet Synchronous Machine (IPMSM) is devised. And, q-axis current reference (iqsr*) is modified for the unity power factor operation to AC source. The proposed scheme has been applied to inverter driven 1 kW compressor of an air-conditioner. From the experimental results, it has been verified that the compressor operates well at required operating condition regardless of the severe fluctuation of DC-link voltage due to the reduced DC-link capacitor. Also the frequency spectrum of the AC source current reveals that the harmonics of the source current meet IEC 61000-3-2 Class A and that the overall power factor is above 97% without any additional circuit such as an input filter and the power factor correction circuit.