Research And Design Of Frequency-programmable AC Signal Source Of PEM Impedance Monitoring

The fuel cell has already drawed worldwide attention as a clean and green power device of hydrogen. The impedance of the fuel cell greatly indicates the performance of the fuel cell as a significant parameter which is important to test.The inverter AC signal source is supposed to be one of the most critical part of the measuring system of fuel cell's impedance. A study on the inverter AC signal source is finished in this paper in which the programmability of the wide range of frequency and amplitude is centure issue.The main content of this paper is described as the following.The paper decides the scheme of each hardware module according to the signal source's overall program which is particularly determined by the quality index of the inverter AC signal source and the application environment. The hardware contains four modules which are the DC/DC transform method,the main inverter circuit of DC/AC,the power MOS of the inverter and the driver of it.The main effort is put on the design of the key points including the choice of the power MOS in the DC/DC module,the RCD snubber circuit and the inverter driver.The mathematical model is built with state space method. The type of the load covers the pure resistance and any load else in the model which is built with continuous domain space method.The single loop of voltage and the double loop of voltage and current is designed based on the inverter model of discrete state space.The inductor-current and the capacity-current feedback are two normal choices about the inner current loop.The paper chooses the capacity-current feedback to ues by overall comparing the performance of error tracking and interference immunity of the two feedback.The output waveform turns out to be nice indicating the feasible of the design of the signal source for on-line measuring of the impendance of fuel cell.The quality target has achieved and it's easy to get the testing result of the impendance of fuel cell cooperating with the mother board.