Variable coil configuration system, apparatus and method
One or more variable configuration controller (VCC) systems may produce various combinations of series or parallel couplings of coils, winding or inductive elements of an electric machine such as a generator and/or electric motor. The VCC systems include a plurality of bridge rectifiers, and a first number of switches operated to selectively couple respective pairs of coils in series from parallel on an AC side of the bridge rectifiers. The bridge rectifiers provide for automatic electrical isolation of coils on occurrence of open circuit, low voltage or short circuit conditions. A second number of switches with different performance characteristics (e.g., speed, loss) than the first number of switches may be coupled in parallel with respective ones of the first number of switches. Power factor correction may be used.
1. A variable coil configuration system, comprising:
a plurality of bridge rectifiers, the bridge rectifiers each having a pair of AC nodes on an AC side of the respective bridge rectifier and a pair of DC nodes on a DC side of the respective bridge rectifier, wherein the pair of AC nodes for each bridge rectifier in the plurality of bridge rectifiers is electrically connectable to a coil of an electric machine;
a first number of switches, each of the switches of the first number of switches on the AC side of a respective one of the bridge rectifiers, wherein each switch in the first number of switches is electrically connectable between two coils in the electric machine such that, in operation, for each of the switches electrically connected between two coils in the electric machine, the bridge rectifiers couple the two coils electrically in parallel with one another when the switch is open and the two coils are not subject to an open circuit condition, a low voltage condition or a short circuit condition, and the switch selectively electrically couples the two coils in series with one another when the switch is closed; and
a second number of switches, each of the switches of the second number of switches electrically connected in parallel with respective ones of the first number of switches, wherein the switches of the first number of switches are faster acting than the switches of the second number of switches and the switches of the second number of switches have a lower associated electrical loss than an electrical loss associated with the switches of the first number of switches.
2. The variable coil configuration system of claim 1 wherein the bridge rectifiers automatically electrically isolate a respective one of the coils of the electric machine from a parallel combination with at least one other one of the coils of the electric machine when the respective one of the coils experiences either a short circuit condition, a low voltage condition or an open-circuit condition.
3. The variable coil configuration system of claim 2 wherein the bridge rectifiers automatically electrically couple the respective one of the coils of the electric machine in series with at least one other one of the coils of the electric machine when the respective one of the coils experiences either the short circuit condition, the low voltage condition or the open-circuit condition.
4. The variable coil configuration system of claim 1 wherein the first number of switches are semiconductor based switches.
5. The variable coil configuration system of claim 4 wherein the first number of switches are TRIACS.
6. The variable coil configuration system of claim 5 , further comprising:
a controller configured to switch the TRIACS at a respective zero crossings of a respective current.
7. The variable coil configuration system of claim 1 wherein the second number of switches are mechanical switches.
8. The variable coil configuration system of claim 1 wherein the first number of switches are mechanical switches.
9. The variable coil configuration system of claim 1 wherein all of the bridge rectifiers of the plurality of bridge rectifiers are coupled to a common heat sink.
10. The variable coil configuration system of claim 1 , further comprising:
a power factor correction circuit applying a power factor correction at a DC output of the variable coil configuration system.
11. The variable coil configuration system of claim 1 wherein a number of active switches are selectively operable to reverse a current flow from a DC bus to the coils to operate the electric machine as a motor.
12. The variable coil configuration system of claim 1 , further comprising:
an additional bridge rectifier coupled to an end of a string formed by the bridge rectifiers of the first number of bridge rectifiers to couple the variable coil configuration electrically in parallel with a second variable coil configuration system;
at least one additional switch operable to selectively couple the variable coil configuration electrically in series with the second variable coil configuration system; and
a coupler configured to detachably electrically couple the second variable coil configuration system to the variable coil configuration system.
13. A method of operating a variable coil configuration system that comprises a plurality of bridge rectifiers, the bridge rectifiers each having a pair of AC nodes on an AC side of the respective bridge rectifier and a pair of DC nodes on a DC side of the respective bridge rectifier and a first number of switches, each of the switches of the first number of switches a semiconductor based switch on the AC side of a respective one of the bridge rectifiers,
wherein each of the switches in the first number of switches is electrically connectable to at least two coils of an electric machine, the variable coil configuration system further comprising a second number of switches, each of the switches of the second number of switches electrically connected in parallel with a respective one of the switches of the first number of switches, wherein the switches of the first number of switches are faster acting than the switches of the second number of switches and the switches of the second number of switches have a lower associated electrical loss than an electrical loss associated with the switches of the first number of switches, the method comprising:
electrically coupling at least two coils of the electric machine in parallel with one another via a respective one of the bridge rectifiers when the switch connected to the at least two coils of the electric machine is open and wherein the two coils are not subject to an open circuit condition, a low voltage condition or a short circuit condition,
electrically coupling the at least two coils of the electric machine in series with one another when the switch connected to the at least two coils of the electric machine is closed; and
for the coils of the electric machine that are electrically coupled in series with one another by the respective switch of the first number of switches, further coupling the coils of the electric machine electrically in series with one another by a respective one of the switches of the second number of switches concurrently with or immediately following the coupling electrically in series of the coils by the respective switch of the first number of switches.
14. The method of claim 13 wherein selectively coupling at least two coils of the electric machine electrically in parallel with one another via a respective one of the bridge rectifiers includes selectively coupling a first two coils electrically in parallel with one another at a first time and wherein selectively coupling at least one pair of coils of the electric machine electrically in series with one another via a respective one of the first number of switches includes selectively coupling the first two coils electrically in series with one another at a second time, different from the first time.
15. The method of claim 13 wherein selectively coupling at least two coils of the electric machine electrically in parallel with one another via a respective one of the bridge rectifiers includes selectively coupling a first two coils electrically in parallel with one another at a first time and wherein selectively coupling at least one pair of coils of the electric machine electrically in series with one another via a respective one of the first number of switches includes selectively coupling a second two coils, different from the first two coils, electrically in series with one another during the first time.
16. The method of claim 13 , further comprising:
switching a state of the switches of the first number of switches by a controller at a respective zero crossings of a respective current.
17. The method of claim 13 , further comprising:
automatically electrically isolating a respective one of the coils of the electric machine from a parallel combination with at least one other one of the coils of the electric machine by a respective one of the bridge rectifiers when the respective one of the coils experiences either a short circuit condition, a low voltage condition or an open-circuit condition.
18. The method of claim 17 , further comprising:
automatically electrically coupling the respective one of the coils of the electric machine in series with at least one other one of the coils of the electric machine when the respective one of the coils experiences either the short circuit condition, the low voltage condition or the open-circuit condition.
19. The method of claim 13 , further comprising:
correcting a power factor of a current at a DC output of the variable coil configuration system.
20. The method of claim 13 , further comprising:
selectively reversing a current flow from a DC bus to the coils to operate the electric machine as a motor.
21. The method of claim 13 , further comprising:
detachably electrically coupling a second variable coil configuration system to the variable coil configuration system.
22. The method of claim 13 wherein selectively coupling at least two coils of the electric machine electrically in series with one another via a respective one of the first number of switches includes selectively coupling at least two coils of the electric machine electrically in series with one another via a triac, an insulated gate bipolar transistor, a field effect transistor or a solid state relay.