A system for controlling an inductor freewheeling voltage, comprising:
- a first switch;
- a second switch, wherein at least one of the first switch and/or the second switch is a unipolar transistor or IGBT transistor;
- a first diode;
- an inductor;
- and
- a switch control circuit,
- wherein the first switch has an open state in which the first switch connects a first terminal of the inductor with a power bus, the first switch being controlled by a first control signal,
- wherein a first terminal of the first diode is connected to a ground, and a second terminal of the first diode is connected to the first terminal of the inductor,
- wherein the first diode is connected to permit an electric current to pass from the ground to the first terminal of the inductor,
- wherein the second switch has an open state in which the first switch connects a second terminal of the inductor with the ground,
- wherein the switch control circuit comprises a second resistor, a third resistor, a fourth resistor, a third diode, a transistor, and a plurality of Zener diodes,
- wherein the plurality of Zener diodes is connected such that:
- a first terminal of a first Zener diode from the plurality of Zener diodes is connected to the second terminal of the inductor;
- a second terminal of a last Zener diode from the plurality of Zener diodes is connected to a first terminal of the third diode, wherein the plurality of Zener diodes are connected in series, in the same direction and a forward direction of the Zener diodes from the first terminal of the third diode to the second terminal of the inductor;
- a second terminal of the third diode is connected to a first terminal of the second resistor, and to a base terminal of the transistor, wherein a forward direction of the third diode is from the second terminal of the last Zener diode of the plurality of Zener diodes to the first terminal of the second resistor,
- a second terminal of the second resistor is connected to the ground, a collector terminal of the transistor is connected to an auxiliary power supply configured to provide stable DC voltage,
- an emitter terminal of the transistor is connected to the input terminal and to a first terminal of the third resistor, a second terminal of the third resistor is connected to a first terminal of the fourth resistor, and to a gate terminal of the second switch, a second terminal of the fourth resistor is connected to the ground
- is configured to be controlled with a second control signal that is delivered to an input terminal of the switch control circuit, such that in a first state of the second control signal the switch control circuit keeps the second switch open and in a second state of the second control signal the switch control circuit keeps the second switch such that there is a voltage drop across the second switch.