Direct current actuator control system using pulse-width modulation in four bipolar transistors connected in H-manner

A system for the control of direct current actuators in power electronics, based on pulse width modulation, comprising:

• a H-bridge of four switches, each switch incorporating a transistor and a diode connected in reverse parallel between the emitter and the collector thereof;
• a control circuit for said transistors, wherein each transistor is of the bipolar type and wherein the control circuit supplies four signals permitting the time shifting of the switching of these four transistors in such a way that, during a switching of one of them, no pair of transistors is switched on simultaneously, either with respect to the transistors belonging to the lateral branches of the bridge or the transistors belonging to the two opposite sides of the bridge;
• and
• for controlling the transistors of the top of the bridge, two switching power supplies based on an oscillator driving a mains transformer, wherein, at the secondary of said transformer, the signal is rectified and filtered to supply the voltages +Va and -Va and +Vb and -Vb, wherein each of the second signals is overmodulated to drive a control transformer, said overmodulation being obtained through the same oscillator and a modulation logic and wherein for driving the corresponding bridge bipolar transistor, the signal is demodulated with the aid of a rectifier and amplified adapting the level thereof.

A system for the control of direct current actuators in power electronics, based on pulse width modulation, comprising:

• a H-bridge of four switches, each switch incorporating a transistor and a diode connected in reverse parallel between the emitter and the collector thereof, a control circuit for said transistors, wherein each transistor is of the bipolar type and wherein the control circuit supplies four signals permitting the time shifting of the switching of these four transistors in such a way that, during switching of one of them, no pair of transistors is switched on simultaneously, either with respect to the transistors belonging to the lateral branches of the bridge or the transistors belonging to the two opposite sides of the bridge;
• four drivers and a Hall effect current measuring means for closing the current servoloop, a resistor for measuring the current;
• and
• two top drivers, in which the secondary of the switching power supply is constituted on the one hand by a rectification implemented by four Schottky diodes for limiting the voltage drop and on the other by a filtering implemented by two capacitors for obtaining two symmetrical voltages supplying the power stage and wherein said power stage is constituted by the pulse transformer making it possible to recover the modulated signal from the logic modulation module, demodulation being performed by the two Schottky diodes connected in rectifier form with the centre point, the thus rectified signal driving a push-pull-type transistor amplifier, the floating earth of the supply being connected to the emitter of the power amplifier.