SINGLE-PHASE THREE-WIRE POWER CONTROL SYSTEM AND POWER CONTROL METHOD THEREFOR

• US 20150207433A1
• Filed: 01/14/2015
• Published: 07/23/2015
• Est. Priority Date: 01/22/2014
• Status: Active Grant

• Current Assignee: Lite-On Electronics Company Limited (Lite-On Technology Corporation), Lite-On Technology Corporation
• Original Assignee: Lite-On Electronics Company Limited (Lite-On Technology Corporation), Lite-On Technology Corporation
• Inventors: WU, TSAI-FU, CHANG, CHIH-HAO, LIU, YUNG-HSIANG, LO, SHUN-HUNG, WANG, KAI-LI, YANG, JENG-GUNG, LIU, HUAN-CHENG
• Granted Patent: US 9,413,270 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02M 1/40 Means for preventing magnetic saturation
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current

Abstract

The present disclosure provides a single-phase three-wire power control system integrating the electricity of a DC power supply device to an AC power source. The single-phase three-wire power control system comprises a single-phase three-wire inverter, a driving unit, a sampling unit and a processing unit. The single-phase three-wire inverter coupled between the DC power supply device and the AC power source converts a DC voltage of the DC power supply device to an output voltage. The driving unit is coupled to the single-phase three-wire inverter. The sampling unit samples the inductor current of an inductor of the single-phase three-wire inverter. The processing unit which is coupled to the driving unit and the sampling unit controls the single-phase three-wire inverter through the driving unit. The processing unit obtains the duty ratio according to the inductance of the inductor, the total variation of the inductor current, the DC voltage and the output voltage.

Claims

1. A single-phase three-wire power control system integrating the electricity of a DC power supply device to an AC power source through an inductor of a first power line, a second power line and a third power line, comprising:

a single-phase three-wire inverter, coupled between the DC power supply device and the AC power source, converting a DC voltage of the DC power supply device to an output voltage, wherein the single-phase three-wire inverter has a first half-bridge DC-AC power converter and a second half-bridge DC-AC power converter parallel-coupled to each other;

a driving unit, coupled to the single-phase three-wire inverter;

a sampling unit, coupled to the inductor, sampling an inductor current of the inductor; and

a processing unit, coupled to the driving unit and the sampling unit, controlling the single-phase three-wire inverter through the driving unit, obtaining the duty ratio of a next cycle according to the inductance of the inductor, the total variation of the inductor current, the DC voltage and the output voltage;

wherein the processing unit obtains a current variation of exciting the inductor and a current variation of demagnetizing the inductor according to the DC voltage of a present cycle, the output voltage, the inductance of the inductor and the duty ratio of the present cycle, and obtains the total variation of the inductor current in the present cycle according to the current variation of exciting the inductor and the current variation of the demagnetized inductor in the present cycle.

2. The single-phase three-wire power control system according to claim 1, wherein the first half-bridge DC-AC power converter and the second half-bridge DC-AC power converter are both bipolarized switched;

the first-bridge DC-AC power converter is connected to the first power line, the second-bridge DC-AC power converter is connected to the second power line;

the processing unit utilizes feed-forward current control to obtain the total variation of the inductor current according to a reference current and a feedback current of the present cycle, wherein the feedback current is the inductor current multiplied with a scale factor.

3. The single-phase three-wire power control system according to claim 1, wherein the three-wire power control system operates in an grid-connection mode and a rectification mode, wherein when the three-wire power control system operates in the grid-connection mode, the duty ratio of the next cycle is characterized by the equation:

4. The single-phase three-wire power control system according to claim 1 wherein the single-phase three-wire power control system operates in a voltage-control mode, the processing unit obtains the total current variation of a load according to a reference voltage and a feedback voltage, the load is equalized as a resistive load, a inductive load and a capacitive load connected in parallel, the total current variation of the load is the summation of the current variation of the resistive load, the current variation of the inductive load and the current variation of the capacitive load.

5. The single-phase three-wire power control system according to claim 4, wherein the total variation of the load is characterized by the equation:

6. The single-phase three-wire power control system according to claim 4, wherein the processing utilizes iterative learning control to compensate the output voltage, wherein the variation of the duty ratio for the iterative learning is characterized by the equation:

7. A power control method for controlling a single-phase three-wire power control system, the single-phase three-wire power control system having a single-phase three-wire inverter, the single-phase three-wire inverter is coupled between a DC power supply device and a AC power source for converting a DC voltage of the DC power supply device to an output voltage and integrating the electricity of the DC power supply device to the AC power source through an inductor of a first power line, a second power line and a third power line, wherein the single-phase three-wire inverter has a first half-bridge DC-AC power converter and a second half-bridge DC-AC power converter parallel-coupled to each other, the power control method comprising:

obtaining the duty ratio of a next cycle according to the inductance of the inductor, the total variation of the inductor current, the DC voltage and the output voltage;

obtaining a current variation of exciting the inductor and a current variation of demagnetizing the inductor according to the DC voltage, the output voltage, the inductance of the inductor in a present cycle and the duty ratio of the present cycle; and

obtaining the total variation of the inductor current in the present cycle according to the current variation of exciting the inductor and the current variation of demagnetizing the inductor in the present cycle.

8. The power control method according to claim 7, further comprising:

when the single-phase three-wire inverter operates in an grid-connection mode, calculating the duty ratio of the next cycle according to following equation;

9. The power control method according to claim 8, further comprising:

When the single-phase three-wire power control system operates in a voltage-control mode, obtaining the total current variation of a load according to a reference voltage and a feedback voltage, equalizing the load as a resistive load, a inductive load and a capacitive load connected in parallel, wherein the total current variation of the load is the summation of the current variation of the resistive load, the current variation of the inductive load and the current variation of the capacitive load, then calculating the variation of the duty ratio estimated from the load according to the total current variation of the load.

10. The power control method according to claim 9, wherein calculating the total current variation of the load according to the following equation: