| 摘要 |
The condition of an electricity producing cell, such as a fuel cell, photovoltaic cell or electrochemical cell, is determined by applying a broadband signal to the cell and measuring the voltage and/or current response of the cell. The broadband signal is a plurality of superimposed waveforms, e.g. sinusoids, at different frequency set points and is optimized to have reduced peak amplitudes. The distribution of frequency set points may be linear at the upper and lower portions of the frequency range and logarithmic in the mid-range. The amplitudes of the sinusoids may also vary across the frequency range. The phase vectors of the waveforms may be arranged to reduce the crest factor of the broadband signal. The broadband signal may span from 0.1 Hz to 10 kHz. An apparatus for monitoring a fuel cell 126 includes a DSP 102 with a memory 110 for storing signal vectors, a current regulator 124 to apply current to the fuel cell and means 128, 130 to measure voltage and current. |
