Alternator rectifier with coil-sensor controlled MOSFETs
View Patent ↗A switching circuit for an electric machine is provided. The switching circuit includes switches for energizing the phase windings of the machine and sensors for driving the state of the switches. The switches are voltage-controlled devices and the sensors are coils.
1. A switching circuit for an electric machine, the electric machine including a rotor and a stator with plurality of phase windings in the stator, the switching circuit comprising:
a plurality of switches each switch connected to at least one of the plurality of phase windings;
a plurality of coils, each coil being located in the stator of the electric machine and in communication with a switch of the plurality of switches to manipulate a state of the switch based on a current flowing through a phase winding of the plurality of phase windings.
2. The coils according to claim 1 , wherein each coil being located proximate to at least one phase winding of the plurality of phase windings and configured to control at least one switch of the plurality of switches.
3. The switching circuit according to claim 1 , wherein each coil is an L-turn coil where L is chosen so that the voltage signal of each coil is between the threshold and the maximum allowable controlling voltage of the switches.
4. The switching circuit according to claim 3 , wherein L is about one to two times of (N*M)/2 where N is the number of turns of the phase windings and M is the number of pairs of rotor poles.
5. The switching circuit according to claim 1 , wherein each coil is wound within the span of about one to two pitches of the phase winding.
6. The switching circuit according to claim 1 , wherein the switch is a MOSFET.
7. The switching circuit according to claim 6 , wherein the switch is an N-channel MOSFET.
8. The switching circuit according to claim 6 , wherein each coil is connected across the gate and the source of the MOSFET.
9. The switching circuit according to claim 6 , wherein each coil is an L-turn coil where L is chosen so that the voltage signal of each coil is between the threshold and the maximum allowable gate to source voltages of the MOSFETs.
10. The switching circuit according to claim 1 , wherein pairs of switches of the plurality of switches are configured in a bridge configuration to energize at least one of the plurality of phase windings.
11. The switching circuit according to claim 1 , wherein the switch is an IGBT.
12. The switching circuit according to claim 11 , wherein the coil is an L turn coil where L is chosen so that the voltage signal of the coil is between a threshold and the maximum allowable gate to emitter voltages of the IGBT.