The invention relates to a control device of two bipolar transistors connected ins eries between conductors of a direct operating voltage supply and having a center output point to form an inverter arm, each transistor having a base control unit supplied by a direct control voltage source.
To each phase of the inverter there corresponds an arm having two transistors in series subjected to the operating voltage which generally reaches several hundred volts. Each transistor has associated with it a base control capable of supplying a base current of several amps at a low voltage, notably a few volts, to make the transistor conducting and a low negative voltage blocking the transistor. These control voltages are generally speaking derived from the high operating voltages, which gives rise to insulation problems in the case of the inverter arm with two transistors connected in series.