Three-phase detection module

1. An apparatus comprising:

a first optocoupler that selectively allows a first current to flow from a first one of a first pair of N power supply lines to a second one of the first pair, wherein the N power supply lines each provide a phase signal, and wherein N is an integer greater than two;

a control module that controls the first optocoupler and that determines an occurrence of a phase failure of the phase signals based on a first signal, which is based on the first current; and

an output optocoupler that generates the first signal based on a total current including the first current.

2. The apparatus of claim 1 further comprising second and third optocouplers that selectively allow current to flow between second and third pairs of the N power supply lines, respectively, and wherein the control module controls the second and third optocouplers.

3. The apparatus of claim 2 wherein a plurality of optocouplers includes the first, second, and third optocouplers, wherein the control module deactivates others of the optocouplers when activating one of the optocouplers, and wherein each of the plurality of optocouplers allows current to flow while activated.

4. The apparatus of claim 2 wherein the first signal is based on the first current when the first optocoupler is activated, the first signal is based on a second current flowing from a first one of a second pair of the N power supply lines to a second one of the second pair when the second optocoupler is activated, and the first signal is based on a third current flowing from a first one of a third pair of the N power supply lines to a second one of the third pair when the third optocoupler is activated.

5. The apparatus of claim 1 wherein the phase failure comprises at least one of a phase loss, a phase order reversal, and a phase magnitude imbalance.

6. The apparatus of claim 1 wherein the total current includes second and third currents from second and third optocouplers.

7. An apparatus comprising:

a first optocoupler that selectively allows a first current to flow from a first one of N power supply lines to a second one of the N power supply lines, wherein the N power supply lines each provide a phase signal, and wherein N is an integer greater than two;

a device that allows current to flow from the second one of the N power supply lines to the first one of the N power supply lines and that prevents current from flowing from the first one of the N power supply lines to the second one of the N power supply lines;

a control module that controls the first optocoupler and that analyzes a first signal, which is based on the first current, to determine a phase failure of the phase signals; and

an output optocoupler that generates the first signal based on a total current including the first current.

8. The apparatus of claim 7 further comprising:

a second optocoupler that selectively allows a second current to flow from the second one of the N power supply lines to a third one of the N power supply lines; and

a third optocoupler that selectively allows a third current to flow from the third one of the N power supply lines to the first one of the N power supply lines.

9. The apparatus of claim 8 , wherein the output optocoupler receives a sum of the first, second, and third currents and generates the total current, and wherein the first, second, and third currents are zero when the first, second, and third optocouplers, respectively, are deactivated.

10. The apparatus of claim 9 further comprising N Zener diodes that each allow current flow from the output optocoupler to a node of a respective one of the first, second, and third optocouplers.

11. The apparatus of claim 10 wherein the N Zener diodes each allow current flow from the node of the respective one of the first, second, and third optocouplers to the output optocoupler when a voltage applied to the Zener diode is above a predetermined threshold.

12. The apparatus of claim 8 further comprising N diodes that each allow current flow from a node of a respective one of the first, second, and third optocouplers to a corresponding one of the N power supply lines, wherein the device comprises one of the N diodes.

13. The apparatus of claim 8 further comprising N resistances, each connected between one of the first, second, and third optocouplers and a respective one of the N power supply lines.

14. The apparatus of claim 7 further comprising N varistors, each connected between a respective two of the N power supply lines.

15. An apparatus comprising:

N resistances, wherein N is an integer greater than two;

N switching devices that each have first and second ends and that each selectively electrically connect the first end to the second end, wherein the first ends are coupled to respective ones of N power lines via the N resistances and wherein the second ends are connected to a common node, wherein each of the N power lines carries a power signal having a different one of N phases;

an output device that is connected between the common node and a second node and that generates an output signal based on a current flowing between the common node and the second node;

N unidirectional devices that each allow current to flow from a node at the first end of a respective one of the N switching devices to a corresponding one of the N power lines and that each inhibit current flow toward the first ends; and

a control module that analyzes the output signal to determine a failure of the power signals and that selectively generates N control signals that respectively control the N switching devices.

16. The apparatus of claim 15 further comprising N Zener diodes that each allow current to flow from the second node to the node at the first end of a respective one of the N switching devices and that each selectively inhibit current flow toward the second node.

17. The apparatus of claim 15 wherein each of the N unidirectional devices comprises a diode.

18. The apparatus of claim 15 wherein each of the N switching devices comprises an optocoupler.

19. The apparatus of claim 15 wherein the output device comprises an optocoupler.

20. The apparatus of claim 15 further comprising N varistors that are each connected between two of the N power lines.