1990-08-01

A Maximum Power Point Tracker Optimized for Solar Powered Cars 901529

The following is an efficiency study of a key component in a solar powered car: the maximum power point tracker (MPPT). An MPPT is necessary where to maximize the power delivered from solar cells to batteries. A design optimization for the tracker is crucial for its use in solar powered cars since these vehicles have a very limited amount of input power. Unfortunately, the power stage of a maximum power tracker, consisting of inductors, capacitors, diodes, and MOSFETs, may waste a small yet significant percentage of the total power out of the solar cells. Most trackers today are about 95% efficient. The objective here is to raise the efficiency to 98%.Once the input and output current and voltages have been selected, each component of the tracker can be optimized for maximum efficiency. After examining the conduction, switching, and gate losses of the MOSFET and diode, the optimum design can be found. The key to making the tracker most efficient is to look at the entire package of parts and optimize several variables at once: frequency, number of devices in parallel (a method of reducing resistive losses), and heat sinking. Using this information, other circuit configurations can be analyzed and external variables can be manipulated to obtain the maximum efficiency. Additional crucial parameters such as weight, cost and space taken up by the tracker must be considered in the design. In the end, based on the key equations which are derived, a super efficient maximum power point tracker can be designed and built to the specifications of the user.

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