Improvement of Input Current Waveforms for a Matrix Converter Using a Novel Hybrid Commutation Method

This paper proposes a novel hybrid commutation method and a compensation method for the output voltage error and input current error of a matrix converter in order to improve the input current. The proposed commutation method combines input voltage commutation and load current commutation. There are two conventional commutation methods; one that depends on the polarity of the input line voltage and is called voltage commutation, and one that depends on the polarity of the output current and is called current commutation. However, a problem with voltage commutation is that commutation failure occurs at around an input line voltage of zero. It is difficult to detect the voltage polarity due to dependence on the offset and delay of the sensor. Similarly, current commutation failure occurs at around a load current of zero. The cause of these detection errors are detection delay and the offset of the sensor. However, the proposed commutation method can decrease the commutation failure without the need for a high accuracy sensor, because the current commutation is compensated by the voltage commutation. In addition, a new commutation error compensation method is proposed for the proposed commutation. The output voltage and input current error are compensated at the same time, because the duty ratio of each switch is directly compensated. The proposed method is validated based on the experimental results with a 750 W induction motor and a R-L load. The total harmonic distortion (THD) of the input current and the output current with the proposed hybrid commutation are 3.9% and 2.1%, respectively, and are obtained for an induction motor load with vector control.