Generator power system and method

• US 5,563,802 A
• Filed: 01/31/1996
• Issued: 10/08/1996
• Est. Priority Date: 01/26/1994
• Status: Expired due to Term

• Current Assignee: Cummins PowerGen IP, Inc. (Cummins Incorporated)
• Original Assignee: ONAN Corporation (Cummins Incorporated)
• Inventors: Plahn, Paul H., Miller, Mike C., Koenig, David J.
• Primary Examiner(s): Cosimano, Edward R.
• Application Number:
  US08/594,779
• Time in Patent Office: 251 Days
• Field of Search: 290/1 R, 307/64, 307/65, 307/66, 307/67, 307/75, 364/492, 364/494
• US Class Current: 700/297
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02J 9/08 requiring starting of a prime-mover

Abstract

An integrated power system includes an engine/generator power supply integrated with storage batteries to provide household-like AC power. For a small load demand, the storage batteries are used to provide electricity. For a large load demand, the engine/generator starts to supply electricity. The engine/generator also recharges the storage batteries if the load demand is smaller than the engine/generator maximum load capacity. For a larger load demand, both the engine/generator and the storage batteries supply electricity in parallel. The engine speed is variable for various loads. The bigger the load, the higher the engine speed is required to produce the necessary power and keep a constant high DC voltage.

Claims

1. An integrated power apparatus, comprising:

engine/generator means for providing a first direct current voltage output to a direct current voltage bus;

inverter means for inverting direct current voltage of the direct current voltage bus to alternating current;

battery means for providing a second direct current voltage output for the direct current voltage bus;

charging means for charging the battery means;

boost means for boosting the second direct current voltage output of the battery means to provide the direct current voltage bus with boosted second direct current voltage output; and

control means for integrating the battery means and the engine/generator means according to a predetermined control logic, wherein the engine/generator means is off and the battery means is the exclusive source of power during a first electrical load condition, the engine/generator is the exclusive source of power during a second electrical load condition, the engine/generator means is the exclusive source of power and simultaneously charges the battery means during a third electrical load condition, the engine/generator means and the battery means both provide power during a fourth electrical load condition.

2. An apparatus in accordance with claim 1, wherein the control means includes a microprocessor means, the apparatus further includes sensing means for sensing AC voltage output of the inverter means and sending an electrical signal to the microprocessor means, the microprocessor means sending an electrical signal to the inverter means to maintain the required AC voltage.

3. An apparatus in accordance with to claim 1 including means for allowing the boosted voltage of the battery means to be supplied to the direct current bus when the boosted direct current voltage of the battery means is higher than the direct current voltage on the direct current voltage bus, and isolating the output of the battery means from the direct current bus when the boosted voltage of the battery means is lower than the voltage of the generator/set means.

4. An apparatus in accordance with claim 1, wherein the battery means is a set of 12-volt batteries.

5. An apparatus in accordance with claim 1, wherein the inverter means includes means for outputting a synthesized sine wave.

6. An apparatus in accordance with claim 1, wherein the battery charging means output is regulated to 50 amps with the output being maintained at a constant current until the voltage of the battery means reaches roughly a temperature compensated 14.2 volts DC, voltage output is then reduced to roughly a temperature compensated 13.6 volts.

7. An apparatus in accordance with claim 1, wherein the control means includes a microprocessor means, the apparatus further includes sensing means for sensing the direct current voltage at an input of the inverter means and transmitting an electrical signal representative of the sensed voltage to the microprocessor means for processing of the signal, the microprocessor means sending an electrical signal to the engine/generator for controlling engine/generator speed as required to maintain constant voltage.

8. An apparatus in accordance with claim 7, wherein the speed of the engine/generator means is increased in stair step fashion to maintain constant voltage in response to increasing electrical load.

9. An apparatus in accordance with claim 1, wherein the control means includes a microprocessor means, the apparatus further includes sensing means for sensing a charging current at an input of the battery means and sending an electrical signal to the microprocessor means, the microprocessor means sending an electrical signal to the charging means to control the charging of the battery means.

10. An apparatus in accordance with claim 9, wherein the control means causes controls the charging of the battery means in response to the charging current sensed by the sensing means.

11. An apparatus in accordance with claim 1, wherein the control means includes a microprocessor means, the apparatus further includes battery voltage sensing means for sensing the voltage of the battery means and sending an electrical signal to the microprocessor means.

12. An apparatus in accordance with claim 11, wherein the control means causes the battery charging means to charge the battery means upon the battery voltage sensing means sensing a predetermined low battery voltage.

13. An apparatus in accordance with claim 11, wherein the control starts the engine/generator means upon the battery voltage sensing means sensing a predetermined low battery voltage.

14. An apparatus in accordance with claim 1, wherein the control means includes a microprocessor means, the apparatus further includes sensing means for sensing current at the output of the inverter means and sending an electrical signal to the microprocessor means.

15. An apparatus in accordance with claim 14, wherein the control means activates the boost means upon the current sensor detecting a transient condition caused by the addition of an electrical load so as to overcome undershoots.

16. An apparatus in accordance with claim 14, wherein the control means activates the charging means upon the current sensor detecting a transient condition caused by the deletion of an electrical load so as to overcome overshoots.

17. An apparatus in accordance with claim 14, wherein the control means operates the engine/generator means at a fixed speed upon the current sensor detecting a predetermined electrical load.

18. A method of providing household-like AC power to electrical loads, comprising the steps of:

providing a first direct current voltage output to a direct current high voltage bus using variable speed engine/generator means, engine speed of the engine/generator means being varied to maintain constant voltage on the high voltage bus;

inverting the direct current voltage of the direct current voltage bus to alternating current using inverter means;

providing a second direct current voltage output to the direct current high voltage bus using at least one DC battery, including the step of boosting the second direct current voltage output from the DC battery;

charging the battery means using charging means, power for the charging means being provided by the engine/generator means; and

integrating the battery means and the engine/generator means using control means according to a predetermined control logic, wherein the engine/generator means is off and the battery means is the exclusive source of power during a first electrical load condition, the engine/generator is the exclusive source of power during a second electrical load condition, the engine/generator means is the exclusive source of power and simultaneously charges the battery means during a third electrical load condition, the engine/generator means and the battery means both provide power during a fourth electrical load condition.

19. A method in accordance with claim 18, including the step of sensing current at an output of the inverter means and initiating boosting of the battery voltage upon detection of electrical load being added thereby eliminating undershoots and initiating charging of the DC battery upon detection of electrical load being deleted thereby deleting overshoots.

20. An integrated power apparatus, comprising:

engine/generator means for providing a first direct current voltage output to a direct current voltage bus;

inverter means for inverting direct current voltage of the direct current voltage bus to alternating current;

battery means for providing a second direct current voltage output for the direct current voltage bus;

charging means for charging the battery means;

boost means for boosting the second direct current voltage output of the battery means to provide the direct current voltage bus with boosted second direct current voltage output;

control means for integrating the battery means and the engine/generator means according to a predetermined control logic, wherein the engine/generator means is off and the battery means is the exclusive source of power during a first electrical load condition, the engine/generator is the exclusive source of power during a second electrical load condition, the engine/generator means is the exclusive source of power and simultaneously charges the battery means during a third electrical load condition, the engine/generator means and the battery means both provide power during a fourth electrical load condition;

sensing means for sensing the direct current voltage at an input of the inverter means and transmitting an electrical signal representative of the sensed voltage to microprocessor means for processing of the signal, the microprocessor means sending an electrical signal to the engine/generator for controlling engine/generator speed as required to maintain constant voltage;

sensing means for sensing AC voltage output of the inverter means and sending an electrical signal to the microprocessor means, the microprocessor means sending an electrical signal to the inverter means to maintain the required AC voltage;

battery voltage sensing means for sensing the voltage of the battery means and sending an electrical signal to the microprocessor means;

sensing means for sensing a charging current at an input of the battery means and sending an electrical signal to the microprocessor means, the microprocessor means sending an electrical signal to the charging means to control the charging of the battery means;

sensing means for sensing current at the output of the inverter means and sending an electrical signal to the microprocessor means;

the control means activating the boost means upon the current sensor detecting a transient condition caused by the addition of an electrical load so as to overcome undershoots; and

the control means activating the charging means upon the current sensor detecting a transient condition caused by the deletion of an electrical load so as to overcome overshoots.