Development of a Multi-Mode and Energy Saving MPPT Chip for Wind-Photovoltaic Energy Conversion Systems(I)

This general project integrated with several engineering scopes including VLSI digital and analog chip implementations and wind-photovoltaic energy conversion system (WPECS) in order to develop a multi-mode and energy saving control chip for the WPECS. Not only the maximum power point tracking (MPPT) for the WPECS can be reached by the proposed chip, but the energy saving strategy for the control circuits is also merged as the one of the major function for the chip to cope with various generating conditions. MPPT is the critical technique to enhance conversion efficiency of the WPECS. Through VLSI chip implementation, performance in MPPT can be greatly improved. To support various weather condition and power conversion system, the MPPT chip must perform multi-mode function. In sub-project I, we apply reconfigurable computing (RC) technique to realize a high performance multi-mode all digital MPPT in a WPECS. First, we analyze the difference between the gain-adaptive and the step-adaptive Perturb-and-Observe algorithm to find the common term and design the RC datapath in MPPT. Then, based on system specification, we can design the RC data flow to select the step-adaptive Perturb-and-Observe algorithm under high-precision requirement and select gain-adaptive Perturb-and-Observe algorithm under fast operation requirement. Under various weather and environment conditions, we can choose the higher power conversion one from WPECS based on the RC system architecture design. By this way, we can maintain the high power conversion efficiency in the whole system. Moreover, we can turn-off some circuit devices, which are not operated, to save power loss. We can also select different arithmetic bit-length to meet precision, speed, and power requirement. In addition, due to that the MPPT implementation essentially involves sensing current and voltage, a voltage to digital converter (VDC) instead of the A/D converter in MPPT system is proposed in sub-project II. The VDC is able to convert the voltage to a pulse and which is then sampled by a high frequency clock generated from the phase-locked loop. The objective of the sub-project III and IV are to integrate a WPECS as an experimental platform for the multi-mode and energy saving control chip. In sub-project III, an interleaving DC/DC converter for a 1.5kW photovoltaic array and a standby power converter which serves as the power source for the control circuit are proposed. The wind energy conversion system design is left in sub-project IV which is in charge of the design of a grid-connected inverter and a pulse-width-modulation (PWM) rectifier with high power factor as well as low harmonic distortion. The percentage distribution of the drawn power between the batteries and the power grid is controlled by the grid-connected inverter based on the principle of the state of charge of the batteries. Furthermore, the PWM control circuits, MPPT controller and protection circuits developed in sub-project III and IV will be realized by a full-custom designed chip one by one during the excursion of the project in order to raise reliability and the additional values for conducting system commercialization

Project ID:PB9712-1946
External Project ID:NSC97-2220-E182-002