| Abstract |
lf the integral diodes are used as free-wheeling diodes of a MOSFET half-bridge inverter, the reverse recovery current can be high during the transistor integral diode turn-off. It generates important switching losses and can be induced a transistor failure. In this paper, we show how to take advantage of the negative channel conduction in MOSFET to prevent the integral diode conduction and suppress the reverse recovery current. The current is transferred directly from a transistor channel to the opposite one, avoiding the limitation imposed by the diode conduction. This method requires a very fine adjustment of the delay time between the gate drive signals applied to the two transistors to obtain an optimal switching. So, we propose a method to measure the current during the switching which allows the design of a regulation acting on the transistor gate drive signals, so that we can have a switching with a minimal overcurrent transient. The current measurement, when it is integrated into the converter, must be economical, with a large bandwidth. Experimental results showing the reverse recovery current variations and the behaviour of the measurement device integrated into the converter are presented. |
