High-performance solar photovoltaic ( PV) energy conversion system

• US 20070236187A1
• Filed: 04/07/2006
• Published: 10/11/2007
• Est. Priority Date: 04/07/2006
• Status: Active Grant

• Current Assignee: Yuan Ze University
• Original Assignee: Yuan Ze University
• Inventors: Wang, Wen-Hung, Wai, Rong-Jong
• Granted Patent: US 7,479,774 B2
• Time in Patent Office: Days
• US Class Current: 323/222
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/44 with means for ensuring correct phase sequence
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/346 Passive non-dissipative snubbers
• CPC Class Codes: H02M 3/155 using semiconductor devices only
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y10S 323/904 Touch systems

Abstract

The present invention focuses on the development of a high-performance solar photovoltaic (PV) energy conversion system. The power circuit of the invention is made of a two-stage circuit, connecting a step-up DC-DC converter and a full-bridge inverter in serial. The present invention uses an adaptive perturbation and observation method to increase tracking speed of maximum power position and at the same time reduces energy loss. In addition, the full-bridge inverter'"'"'s output has to have the same phase with the utility power in order to achieve unit power factor and increase the system efficiency. The present invention uses voltage type current control full-bridge inverter to achieve the goal of merging into utility grid. The present invention provides an active Sun tracking system, by utilizing the character of changing in open circuit output voltage with Sun radiation strength to follow the Sun, and decreases the system cost and increases system effectiveness.

Claims

1. A high-performance solar photovoltaic (PV) energy conversion system, comprising:

a solar panel, for absorbing Sun radiation and making photovoltaic conversion to produce electricity;

a high-boost ratio DC/DC conversion circuit, converting low DC electricity to high voltage DC electricity, and outputting to a high voltage bus bar;

a system controller, containing a microprocessor and a drive circuit, responsible for system control;

a full-bridge inverter comprising, four power semiconductors switches, connects to the high voltage bus bar, controlled by the system controller to be used in converting DC voltage to AC voltage;

a clamping inductor, connecting between the full-bridge inverter and utility-grid, used for filtering high frequency components in the output voltage of the inverter, and converting AC voltage output to AC current output; and

a driving device, a low power motor to support and drive the solar panel, and controlled by the system controller to change surface angle of the solar panel.

2. The system as claimed in claim 1, wherein said high-boost ratio DC/DC conversion circuit comprising:

a first winding circuit comprising, a power semiconductor switch, a first winding of a coupling inductor, its polar terminal is defined as connecting to the positive post of the DC input circuit;

a passive regenerative snubber circuit comprising, a clamping diode, a discharging diode and a clamping capacitor;

a second winding circuit comprising a high voltage capacitor and a second winding of the coupling inductor, its polar terminal is defined as connecting to the high voltage capacitor; and

a filter circuit further comprising a filter capacitor and a rectification diode.

3. The system as claimed in claim 1, wherein said microprocessor executes a total sliding mode control strategy, a sun tracking strategy and an adaptive step-perturbation method;

and establishes Sinusoidal Pulse-Width-Modulation output module, outputting Pulse-Width-Modulation signal; and

through the inverter drive circuit to drive the power semiconductor switch of the full-bridge inverter, to control the output current of the inverter.

4. The system as claimed in claim 3, wherein said total sliding mode control strategy comprising:

a system performance plan, planning expected system effectiveness under normal condition;

a curbing controller, eliminating interfering voltage induced by changes in the system parameters, load and unpredictable interference from un-modulized system dynamic state; and

an adaptive observation design, estimating upper boundary of sum of uncertain variables, avoiding control vibration phenomena caused by improper choice of upper boundary of the curbing controller.

5. The system as claimed in claim 3, wherein said Sun tracking strategy executed by the microprocessor is through feedback open circuit voltage of the solar panel to determine rotation direction of the surface of the solar panel and through output signal from the microprocessor to drive the driving device in order to obtain maximum Sun energy.

6. The system as claimed in claim 3, wherein said adaptive step-perturbation method is through feedback output voltage and output current of the solar panel to calculate variation in output power and output voltage to adjust step-perturbation voltage, and through indirect control of output current of the inverter to control output voltage of the solar panel.