Direct current power plant

Patent metadata

Field	Value
Publication number	US-11339758-B2
Application number	US-202016990140-A
Country	US
Kind code	B2
Filing date	Aug 11, 2020
Priority date	Jun 19, 2015
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

A DC power plant generating DC power from a variety of engines including a Stirling cycle engine. The DC power plant includes a relatively small start-up power source that is discontinued after the engine is running. A method for producing DC power for a load including starting up an engine using power supplied by a relatively small power supply supplemented by a capacitor bank, 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, disabling output of the DC power during a first set of pre-selected conditions, limiting a rate of change of current of the DC power during a second set of pre-selected conditions, reducing conducted and radiated emissions of the DC power, disconnecting the DC power from the load under a third set of pre-selected conditions, and providing the DC power to the load.

First claim

What is claimed is:

1. A system for producing DC power for an electric grid comprising:
a permanent magnet synchronous motor generator (PMSMG);
a capacitor bank starting the PMSMG in motor mode, the PMSMG powering an engine, the PMSMG producing AC power from output of the powered engine;
a motor drive power board operably coupled to the PMSMG, the motor drive power board converting the AC power to DC power, the PMSMG and the motor drive power board controlling the velocity of the engine; and
an arc fault detector operably coupled to a DC output breaker, the ARC fault detector shunt tripping the DC output breaker during an arc fault condition, the DC output breaker providing the DC power to the electric grid when at least one of an overcurrent or ground fault conditions is false.

2. The system as in claim 1 wherein the arc fault detector comprises operable coupling with an EMI filter.

3. The system as in claim 1 further comprising:
a motor controller controlling the PMSMG including:
an analog/digital converter converting analog sensor signals emanating from the PMSMG to digital signals, the analog/digital converter comprising half bridges across a DC bus and an inductor-capacitor-inductor filter producing three phase AC signals at a predetermined voltage and frequency;
at least one voltage sensor and at least one current sensor supporting three-phase demodulation of the three phase AC signals and conversion of the three-phase AC signals to a two-phase orthogonal reference frame; and
a position/velocity estimator receiving speed sensor signals from the PMSMG and compiling a position and velocity estimation of the PMSMG based at least on the speed sensor signals.

4. The system as in claim 1 wherein the engine comprises a Stirling engine.

5. The system as in claim 1 wherein initially powering the engine comprises:
a first AC power supply including the relatively small power supply, the first AC power supply supplying first power, the engine being initially powered by using the first power and the capacitor bank;
a power control board controlling the engine; and
system control electronics started by using a second power from a second AC power supply, the system control electronics controlling the power control board.

6. The system as in claim 5 wherein the system control electronics comprises:
receiving measured voltage and frequency of the electric grid; and
recording the voltage and frequency in a continuously running log file.

7. The system as in claim 6 wherein receiving measured voltage and frequency comprises:
receiving a CANbus message including the measured voltage and frequency.

8. The system as in claim 6 wherein providing the DC power to the electric grid comprises:
measuring the voltage and frequency by a first digital phase locked loop when the voltage and 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.

Assignees

• Deka Products Lp

Inventors

• Schnellinger Andrew A
• Lowell James R
• Finseth Bryan A
• Barber Christopher L
• Sachs Jason M
• Lucas Donald J
• Prescott Shannon
• Kite Jeffrey W
• Fekete Andras K
• Adams Douglas R

Classifications

• F02G1/043 Primary

  the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines · CPC title

• F02G2275/40

  for starting · CPC title

• F24D11/00

  Central heating systems using heat accumulated in storage masses (self-contained storage heating units F24D15/02) · CPC title

• F02N11/0866

  comprising several power sources, e.g. battery and capacitor or two batteries · CPC title

• H02J1/10

  Parallel operation of DC sources · CPC title