A New Method to Measure the Parasitic Parameter Model of IGBT on Bias Voltage

With the increase in frequency, IGBT can generate serious electromagnetic interference (EMI) when it is turned on and off quickly. The variations in voltage and current produced by switching devices in the transient process are the main sources of high-frequency EMI. The ultrafast switching characteristics of IGBT (i.e., high du/dt or di/dt) will cause serious switching oscillation, EMI noise, and additional power loss. The speed of voltage and current variations in transient process is determined by the interelectrode capacitances of the semiconductor switch. Due to the structural characteristics of IGBT, the interelectrode capacitances will change based on the difference in external voltage. This article introduces an improved method to measure the parasitic inductance and resistance of IGBT. This method perfectly avoids the interference of Z
_ground
which refers to the floating terminal impedance to the ground. The parasitic parameters of IGBT can be obtained by fitting the impedance of IGBT with genetic algorithm. The article also introduces a method to measure the parasitic parameters of IGBT on bias voltage with impedance analyzer and dc source. In the experiment, the capacitance is used to protect the impedance analyzer to avoid the dc current from the dc source. Finally, a double-pulse test circuit is used to verify the parasitic parameter model of IGBT measured in this article. By comparing the current and voltage waveforms when IGBT is turned on and off and the voltage frequency domain waveforms in multiple cycles, it is proved that the parasitic parameter model of IGBT is applicable to the circuit.