Novel solutions for protection of matrix converter to three phase induction machine

Induction motors are traditionally controlled by standard PWM-VS inverters. An alternative is the matrix converter which consists of nine bidirectional switches. This converter has benefits compared to a standard inverter like sinusoidal input current and bidirectional power flow. The main disadvantage is the lack of a bidirectional switch because such a switch may be done by two transistors and two diodes. An important topic is also protection of the matrix converter and this paper proposes two new components´ reduced protection circuits for matrix converters. The number of protection diodes is reduced by 6. Design expressions of the protection circuit are calculated and validated by simulation. The standard protection circuit and the new circuits are demonstrated by simulation to have the same performances. Experimental results on an 8.5 kVA matrix converter show the design expressions are correct. It is concluded that it is possible to reduce the necessary power devices in a matrix converter