Architecture and control method for dynamically conditioning multiple DC sources to drive an AC load

• US 9,496,713 B1
• Filed: 11/29/2012
• Issued: 11/15/2016
• Est. Priority Date: 11/21/2009
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Krolak, Matthew J., Fifield, John M., Liu, Shengyi
• Primary Examiner(s): Cavallari, Daniel
• Application Number:
  US13/689,320
• Time in Patent Office: 1,447 Days
• US Class Current: 1/1
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02M 7/42 Conversion of dc power input into ac power output without possibility of reversal
• CPC Class Codes: H02M 7/493 the static converters being arranged for operation in parallel
• CPC Class Codes: H02S 40/32 comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
• CPC Class Codes: Y02B 10/70 Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A power electronics and control architecture for powering an AC load from a multi-source power system through a single conversion stage is disclosed. A controllable DC-to-AC inverter accepts a DC output voltage range from a DC power source at a DC input, and outputs an adjustable AC at an AC output. A sensor measures an output power of the DC power source to obtain a measured output power, and a processor sets a power level at the DC input based on the measured output power. The processor sets the power level to control the output power of the DC power source, and synchronizes the adjustable AC to a common AC output of the multi-source power system.

Claims

1. A power electronics and control system for powering an AC load from multiple DC power sources each through a respective single conversion stage, the system comprising:

a plurality of controllable DC-to-AC inverters each comprising a control signal input, a DC input, and an AC output;

a plurality of DC power sources each comprising a DC electrical output operable to provide DC electrical power to the DC input of a respective one of the plurality of controllable DC-to-AC inverters;

a plurality of DC sensors each operable to measure at least one characteristic of the DC electrical power output by a respective one of the plurality of DC power sources;

an AC power bus coupling the AC outputs to each other to provide a combined AC electrical power to the AC load;

an AC sensor operable to measure at least one characteristic of the combined AC electrical power provided by the AC power bus to the AC load; and

a processor configured to generate a respective control signal for the control signal input of each of the controllable DC-to-AC inverters based on the measured at least one characteristic of the respective DC electrical power output by each of the DC power sources and the measured at least one characteristic of the combined AC electrical power.

2. The power electronics and control system according to claim 1, wherein at least one of the DC power sources is a load-following power source configured to change the DC electrical power provided at the DC electrical output to follow a demand from the AC load.

3. The power electronics and control system according to claim 2, wherein the processor is configured to generate the respective control signal for the control signal input based on a load-following response time of the at least one load-following source.

4. The power electronics and control system according to claim 1, wherein the DC power sources comprise at least one of the group consisting of:

a fuel cell stack, a wind turbine, a generator, solar cells, a hybrid system, and an energy storage device.

5. The power electronics and control system according to claim 1, wherein the plurality of DC sensors measure at least one of the group consisting of:

a voltage, a current, a power level, an RMS voltage, an RMS current, and an RMS power level.

6. The power electronics and control system according to claim 1, wherein the at least one characteristic of the respective DC electrical output comprises at least one of the group consisting of:

a voltage, a current, a power level, an RMS voltage, an RMS current, and an RMS power level.

7. The power electronics and control system according to claim 1, wherein the processor is configured to generate the respective control signal for the control signal input of each controllable DC-to-AC inverter to manage the respective DC electrical power output by each of the DC power sources.

8. The power electronics and control system according to claim 7, wherein the processor is configured to manage the DC electrical power output by the DC power sources based on a property of the DC power sources, the property comprising one of the group consisting of:

power cost, percent of maximum load, and startup time.

9. The power electronics and control system according to claim 7, wherein the processor is configured to manage the DC electrical power output by the DC power sources based on a property of the DC power sources, the property comprising one of the group consisting of:

an efficiency and a maximum output power.

10. The system according to claim 1, wherein the processor is configured to synchronize, via the control signals, an AC power respectively output by each controllable DC-to-AC inverter with the combined AC electrical power on the AC power bus.

11. The system according to claim 10, wherein the control signals are configured to cause each controllable AC-to-DC inverter to output the respective AC power at a voltage, a frequency, and a phase that matches a voltage, a frequency, and a phase of the combined AC electrical power on the AC power bus.

12. The power electronics and control system according to claim 1, wherein each control signal is a voltage reference signal that causes the respective DC-to-AC inverter to output an AC power as a current amplified replica of the voltage reference signal, wherein the AC power has the same voltage, phase, and frequency as the voltage reference signal, and wherein the AC power has a current that is greater than a current of the voltage reference signal.

13. The power electronics and control system according to claim 1, wherein the plurality of DC power sources comprises a first type of power source and a second type of power source,

wherein the first type includes at least one of the group consisting of:

a fuel cell stack and an energy storage device, and

wherein the second type includes at least one of the group consisting of;

a wind turbine, a generator, solar cells, and a hybrid system.

14. A power electronics and control system for powering an AC load from a plurality of DC power sources each through a respective single conversion stage, wherein at least one of the plurality of DC power sources is a different type of power source than another of the plurality of DC power sources, the system comprising:

a plurality of DC sensors each configured to measure at least one characteristic of a DC electrical power output by a respective one of the plurality of DC power sources;

a plurality of controllable DC-to-AC inverters each including a control signal input, a DC input, and an AC output, wherein each controllable DC-to-AC inverter is configured to receive the DC electrical power at the DC input and output an AC electrical power at the AC output based on a control signal received at the control signal input;

an AC power bus coupling the AC outputs to each other to provide a combined AC electrical power to the AC load;

an AC sensor operable to measure at least one characteristic of the combined AC electrical power provided by the AC power bus to the AC load; and

a processor configured to generate each control signal to synchronize each AC electrical power at each AC output with the combined AC electrical power on the AC power bus,

wherein the processor generates each control signal based on (i) the at least one characteristic of the respective DC electrical power of each of the DC power sources, (ii) a property of the respective DC power source, and (iii) the at least one characteristic of the combined AC electrical power,

wherein the property of the respective DC power source comprises one of the group consisting of;

a startup time of the DC power source, a maximum output power of the DC power source, and a load-following response time of the DC power source.

15. The power electronics and control system of claim 14, wherein the plurality of DC power sources comprises a first type of power source and a second type of power source,

wherein the first type includes at least one of the group consisting of:

a fuel cell stack and an energy storage device, and

wherein the second type includes at least one of the group consisting of;

a wind turbine, a generator, solar cells, and a hybrid system.