Comparison of losses between matrix and indirect matrix converters with an improved modulation

Matrix (MC) and indirect matrix (IMC) converters are direct three-phase to three-phase power converters providing variable frequency and amplitude control of their output voltage. These converters are compact solutions which can be used on industrial adjustable speed drive applications for induction motors. This paper deals with the comparison of the matrix and indirect matrix converter silicon losses for classical industrial applications with constant RMS current load (similar to a constant motor torque). The indirect matrix converter control is extracted from the matrix converter modulation so as to ensure identical instantaneous modulation. Furthermore, the chosen modulation strategy reduces the IMC losses by allowing zero-current switching on the IMC rectifier stage. This paper presents a new reduced losses modulation adapted for indirect converter based on a modified matrix converter modulation which reduces switching voltage step level during a pulse width modulation period. The losses simulations shows that the power losses peak value is about 20% smaller for the matrix compared to the indirect converter. Hence, the matrix cooling system can be significantly reduced compared to the indirect one. The modified modulation increases the number of gate drivers required from six to twelve in the indirect converter rectifier side in comparison with the classical DPWM modulation, but allows to obtain a 14% decrease of its average losses compared to the classical modulation.