Multi-mode renewable power converter system

• US 20040207366A1
• Filed: 04/21/2003
• Published: 10/21/2004
• Est. Priority Date: 04/21/2003
• Status: Active Grant

• Current Assignee: Eaton Phoenixtec MMPL Co. Ltd. (Eaton Corporation PLC.)
• Original Assignee: Eaton Phoenixtec MMPL Co. Ltd. (Eaton Corporation PLC.)
• Inventors: Sung, Chang-Che
• Granted Patent: US 6,914,418 B2
• Time in Patent Office: Days
• US Class Current: 320/140
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A multi-mode renewable power converter system is disclosed. The system includes a control unit, a boost converter, an inverter and optional bi-directional charger, wherein the boost converter converts DC output of a solar cell or a renewable source to high DC bus voltage, and the inverter converts this DC bus voltage to an AC output. This power converter can be used to support standalone load or grid-connected system with a dynamic maximum power point tracking (MPPT) circuit. The MPPT circuit detects the current and voltage from the solar cell and indicates to the inverter to provide power to the load connected. When the optional bi-directional charger is installed, the MPPT signal is also fed to this charger to make the power efficiency maximized for the system.

Claims

1. A multi-mode renewable power converter system, comprising a control unit, a boost converter, an inverter, and an optional bi-directional charger, wherein

the control unit having an input, an output and a control terminal is used for tracking and controlling the system;

the boost converter is used for converting low voltage DC power from a renewable power source to high voltage DC;

the inverter being connected to the DC bus and the output of boost converter is used for converting the DC power to AC for standalone load or grid-connected system; and

the optional bi-directional charger is connected to a storage battery through the DC bus.

2. The multi-mode renewable power converter system as claimed in claim 1, wherein the control unit has a built-in MPPT circuit function to allow the DC output from the renewable power source to reach the maximum power point.

3. The multi-mode renewable power converter system as claimed in claim 1, wherein the input to the boost converter is connected to the DC output of a renewable power source.

4. The multi-mode renewable power converter system as claimed in claim 2, wherein the input to the boost converter is connected to the DC output of a renewable power source.

5. The multi-mode renewable power converter system as claimed in claim 3, wherein the renewable power source can be a solar panel.

6. The multi-mode renewable power converter system as claimed in claim 4, wherein the renewable power source can be a solar panel.

7. The multi-mode renewable power converter system as claimed in claim 1, wherein the boost converter includes a controller, at least one switch and one choke connected to the DC bus for controlling the voltage level on the bus.

8. The multi-mode renewable power converter system as claimed in claim 7, wherein the switch can be implemented with a MOSFET device with the gate electrode being connected to the control terminal of a PWM controller.

9. The multi-mode renewable power converter system as claimed in claim 2, wherein the full bridge inverter includes a voltage loop, a current loop, a mode control switch, and a PWM controller, wherein

the voltage loop connected to the output of the full bridge inverter through a voltage output detector is for monitoring the voltage output from the full bridge inverter;

the current loop connected to the output of the full bridge inverter through a current output detector is for monitoring the current output from the full bridge inverter;

the mode control switch being connected in between the voltage loop and the current loop is directly controlled by the control unit; and

the PWM controller is connected to the output of the voltage loop and the current loop, and multiple output terminals thereof are respectively connected to the input of the full bridge inverter.

10. The multi-mode renewable power converter system as claimed in claim 9, wherein the full bridge inverter is formed by two pairs of alternating switches and a filter, wherein the control terminals of the switches are respectively connected to the inputs of the full bridge inverter, and the input of the filter is connected to the output of the full bridge inverter.

11. The multi-mode renewable power converter system as claimed in claim 9, wherein the voltage loop is formed by a subtractor and an ACC reference signal generator, wherein the subtractor is connected to the output of the full bridge inverter and the reference signal generator.

12. The multi-mode renewable power converter system as claimed in claim 9, wherein the current loop is formed by a multiplier, a subtractor and a reference sine wave generator, wherein the input of the multiplier is connected to the output of the MPPT circuit in the control unit, and the output is connected to the input of the subtractor, and after subtraction with the current output signal from the full bridge inverter the difference value is recorded by the PWM controller.

13. The multi-mode renewable power converter system as claimed in claim 9, wherein the bi-directional charger includes a charge control circuit and a discharge control circuit, wherein the operation of the charge and discharge control circuits are directly controlled by the control unit.

14. The multi-mode renewable power converter system as claimed in claim 10, wherein the bi-directional charger includes a charge mode controller and a discharge mode controller, wherein the operation of the mode controllers are directly controlled by the control unit.

15. The multi-mode renewable power converter system as claimed in claim 11, wherein the bi-directional charger includes a charge mode controller and a discharge mode controller, wherein the operation of the mode controllers are directly controlled by the control unit.

16. The multi-mode renewable power converter system as claimed in claim 13, wherein the bi-directional charger further includes a first and a second switch, a choke, and a charge current control circuit, wherein

the switches are each formed by a PWM controller and a transistor, and each switch is connected by a parasitic or external diode in parallel;

the choke is connected in between the first and second switches, and also connected to the DC bus through the second switch; and

the charge current control circuit includes a comparator and voltage control resistor, where the input of the comparator is respectively connected to the control output and voltage reference signal of the control unit, and the output of the storage battery, whilst the voltage output terminal is connected to the voltage control resistor for adjusting the resistance value, which can be further connected to the current output of the MPPT circuit in the control unit to control the voltage input to the second switch.

17. The multi-mode renewable power converter system as claimed in claim 16, wherein the switch can be implemented with a MOSFET device, and the gate electrode of the device is connected to the control terminal of the PWM controller.

18. The multi-mode renewable power converter system as claimed in claim 1, wherein the input terminals of the bi-directional charger are separately connected to the DC bus for receiving the control signal from the control unit.