Yuan Ze University

Rong-Jong Wai

Rou-Yong Duan

Wen-Hung Wang

Li-Wei Liu

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.

High-performance solar photovoltaic (PV) energy conversion system

The aim of this invention focuses on the development of a high-efficiency bidirectional converter for power sources with great voltage diversity. In traditional bidirectional converters, the circuit topology with transformer form is the common usual. Moreover, the soft-switching techniques including zero-voltage-switching (ZVS) or zero-current-switching (ZCS) are usually used for alleviating the corresponding switching losses. However, there are four and upward power semiconductor switches in these circuit schemes. By this way, it will result in the increase of production cost, and the degeneration of conversion efficiency. The coupled-inductor bidirectional scheme in the proposed converter only adopts three power semiconductor switches to accomplish the objective of bidirectional current control. Under the situation of non-isolation circuit topology, it still possesses the protection of electric safety for operators. Due to the characteristics of high step-up and step-down ratio, the battery module with low voltage could be injected into a high-voltage dc bus for the later utilization, e.g., high-voltage load, front-end of inverter. Since the techniques of voltage clamping, synchronous rectification and soft switching are manipulated in this circuit topology, and the corresponding device specifications are adequately performed, it can achieve the goal of high-efficiency bidirectional power conversion for power sources with great voltage diversity.

High-efficiency high-voltage difference ratio bi-directional converter

The present invention focuses on the development of a high-efficiency single-stage bidirectional converter with multi-input power sources. In the present invention, it takes a three-winding coupled inductor as the main component of energy transmission, and utilizes only two power semiconductor switches to accomplish the multi-input function. According to the designed switching conditions, this circuit could be operated at discharge, charge and standalone states to simplify conventional structure in which multiple converters are used in boosting voltage and then connected in parallel to supply power. Moreover, the coupled inductor as the principal part of this circuit has high-voltage gain property, and the present invention fully utilizes the winding voltage in the high-voltage side to further increase the corresponding voltage gain superior to that in the conventional coupled-inductor strategy. This property is helpful to solve the power conversion problem caused by clean energies with inherent low-voltage characteristics. In addition, all switches and diodes have favorable voltage-clamped effects so that the voltage spikes induced by the leakage-induction energy can be alleviated effectively, and there are no high reverse-recovery currents within diodes because the leakage induction can restrain instantaneous changes in the current. Furthermore, the present invention has a charging route of low-voltage conversion without adding additional components, avoiding the power losses induced by the multistage conversion in the traditional auxiliary power systems, and utilizes the synchronous rectification technique to decrease the conducting losses.

High efficiency single stage bidirectional converter

A current-source sine-wave voltage inverter for converting a direct current (DC) voltage to an alternating (AC) voltage includes a DC source for providing a DC voltage, a current source circuit having a primary side inductance of a transformer, a clamping circuit, an inverting circuit, and a control and driving circuit. The clamping circuit includes a first switch cascaded with a first diode, a second diode cascaded with a second switch, a first capacitor connected between an anode of the first diode and a cathode of the second diode, a secondary side inductance of the transformer cascaded with a third diode, the secondary side inductance of the transformer and the third diode connected to two ends of the DC source, and a cathode of the third diode connected to an anode of the DC source. The present invention also provides a fuel cell system.

Current source wave voltage inverter voltage-clamping and soft-switching techniques, and fuel cell system using the same

A boost converter utilizing bi-directional magnetic energy transfer of coupling inductor provides a high efficiency boost DC-DC converting with above 30 times voltage boost rate, which uses a coupling inductor and low voltage switch to absorb circuit induction voltage of a passive regenerative snubber no matter if switch is turned on or off. Such that, a much higher voltage boost rate than the turn rate of transformer and wider range of switching duty cycle is obtained. A bi-directional magnetic energy path is utilized, that is, when switch is turned on the first winding of coupling inductor stores magnetic excited high current energy, and opposite magnetic flux is induced on the second winding at the same time. When switch is turned off the magnetic excited current continues and increases the voltage on the second winding. The second winding has bi-directional magnetic current induced and fully utilizes capacity of transformer's iron core.

Boost converter utilizing bi-directional magnetic energy transfer of coupling inductor

A hybrid clean-energy power-supply framework integrates a fuel cell, solar cell, and wind energy, applies a max power tracking rule, raises the output power of a solar cell and wind energy to supply a power load and transfer the surplus electrical energy to a water-electrolyzing apparatus for producing hydrogen and oxygen, and provides a fuel for a fuel cell power generating system. Furthermore, the present invention utilizes features of each clean-energy power generating system, depends on the powerful calculation capacity of a central processing unit to monitor and dispatch each power generation and supply system, and thus ensures the reliability of supply power and reduces the power generation cost. Such a framework can selectively grid-connect with the utility power or run as a stand-alone power supply system and has a mechanism for preventing the island effect.

Growing community of inventors

Liouying Township, Tainan County, Taiwan

Rong-Jong Wai