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Maximum power point controller for thermoelectric generators to support a vehicle power supply
Carstens, Jan Hendrik; Gühmann, Clemens
The growing mobility increases the world-wide fuel consumption. Yet the amount of fossil fuel is limited and the environmental burden is increasing dramatically as well. Many governments have enacted laws to regulate and reduce the fuel consumption as well as the CO2 emissions of combustion engines. An idea to save fuel and to reduce the environmental burden is to use thermoelectric generators (TEGs) to recover the waste heat of the exhaust gas and convert into electric energy in automotive applications. For the linking of TEGs to the vehicle is power supply, a DC-DC converter can be used. To support a wide range of TEGs with different electric parameters, the control of DC-DC converter must be robust. Further, the control should track the maximum power point (MPP) of the TEG for an efficient power recovery. This paper presents a digital cascade controller for a boost-buck converter that charges a vehicle battery and supplies the load. To model and analyze the discontinuous converter, the state-space-averaging (SSA) is used. The tracking of the MPP is realized with a gradient algorithm and an input current control. An adaptive step size algorithm reduces the conversion time of the maximum power point tracking algorithm (MPPT). Experiments verified the controller design and the efficiency of the MPPT.
