Direct current power plant

1. A method for starting an engine comprising:

receiving first power from a first AC power supply;

receiving second power from a second AC power supply;

starting the engine by using the first power and a capacitor bank;

starting system control electronics by using the second power;

controlling, by the system control electronics, a power control board; and

controlling, by the power control board, the engine;

providing output from the engine to a permanent magnet synchronous motor generator (PMSMG) operably coupled to the engine;

producing AC power from the output of the PMSMG generator;

coupling a motor drive power board with the PMSMG generator, the motor drive power board converting the AC power to DC power, the PMSMG and the motor drive power board controlling a velocity of the engine;

coupling an arc fault detector to a DC output breaker;

shunt tripping, by the ARC fault detector, the DC output breaker during an arc fault condition; and

providing, by the DC output breaker, the DC power to an electric grid when at least one of a set of pre-selected conditions is false.

2. The method as in claim 1 further comprising:

disabling output of the DC power during a first set of pre-selected conditions.

3. The method as in claim 2 wherein the first set of the pre-selected conditions comprises overcurrent and ground fault conditions.

4. The method as in claim 1 further comprising:

limiting a rate of change of current of the DC power during a second set of pre-selected conditions.

5. The method as in claim 4 wherein the second set of the pre-selected conditions comprises abnormal conditions.

6. The method as in claim 1 further comprising:

reducing conducted and radiated emissions of the DC power.

7. The method as in claim 1 further comprising:

disconnecting the DC power from a load under a third set of pre-selected conditions.

8. The method as in claim 7 wherein the third set of the pre-selected conditions comprises an abnormal overcurrent condition.

9. The method as in claim 1 further comprising:

shunting excess heat of the DC power produced by the engine into a shunt load.

10. The method as in claim 9 further comprising:

heating water with the heat.

11. The method as in claim 1 further comprising:

providing the DC power to an igniter power board, a pump/fan/blower drive, an engine control I/O PCB, a system control PCB, and a power control PCB.

12. The method as in claim 1 further comprising:

receiving an angle from a sawtooth waveform generator;

representing the angle by a 16-bit value, the angle having a sine and a cosine;

applying an average increment to the angle, as an angle sweeps from 0-360°, every 100μsecs, the average increment having a 32-bit center frequency input and a 16-bit delta frequency input driven by a PI controller, the center frequency input representing a fractional value of the angle, the delta frequency oscillating about zero;

producing a sine/cosine pair for the angle;

creating an inverter output waveform based on the sine/cosine pair;

computing a phase error signal based on the sine of the angle and a voltage of a grid supply, the voltage of a grid supply being equal to the cosine of the voltage of the grid supply;

multiplying the sine by the voltage of the grid supply to produce a signal that contains both AC and DC components, the AC component having an amplitude variation based on amplitudes of the grid supply and the inverter output waveform and having a frequency equal to 2x the frequency of the grid supply when loop is locked, the DC component having an amplitude variation based on a phase error between the grid supply and the inverter output waveform;

low pass filtering the phase error; and

eliminating a part of the AC component not relevant to control by supplying the filtered phase error to the PI controller.

13. The method as in claim 1 further comprising:

providing output from the engine to a generator;

producing alternating current (AC) power by the generator;

converting the AC power to direct current (DC) power; and

providing the DC power to an electric grid.

14. The method as in claim 13 further comprising:

measuring voltage and frequency of the electric grid; and

recording the voltage and the frequency in a continuously running log file.

15. The method as in claim 14 further comprising:

reporting, via CANbus, the voltage and the frequency to a system controller.

16. The method as in claim 13 wherein providing the DC power to the electric grid comprises:

measuring a voltage and a frequency by a first digital phase locked loop when the voltage and the frequency are within a pre-selected range of tolerance;

continuously measuring phase error by a second digital phase locked loop;

referencing the measured voltage to the second digital phase locked loop; and

declaring phase lock when the phase error is less than a pre-selected value and when the measured voltage is within a pre-selected range of voltage.

17. The method as in claim 1 wherein the engine comprises a Stirling engine.

18. A method for starting an engine comprising:

receiving first power from a first AC power supply;

receiving second power from a second AC power supply;

starting the engine by using the first power and a capacitor bank;

starting system control electronics by using the second power;

controlling, by the system control electronics, a power control board;

controlling, by the power control board, the engine;

providing output from the engine to a generator;

producing alternating current (AC) power by the generator;

converting the AC power to direct current (DC) power;

providing the DC power to an electric grid;

measuring a voltage and a frequency by a first digital phase locked loop when the voltage and the frequency are within a pre-selected range of tolerance;

continuously measuring phase error by a second digital phase locked loop;

referencing the measured voltage to the second digital phase locked loop; and

declaring phase lock when the phase error is less than a pre-selected value and when the measured voltage is within a pre-selected range of voltage.

19. The method as in claim 18 further comprising:

measuring voltage and frequency of the electric grid; and

recording the voltage and the frequency in a continuously running log file.

20. The method as in claim 19 further comprising reporting, via CANbus, the voltage and the frequency to a system controller.