Online Monitoring Method of P-I-N Diode Temperature Based on Maximum Recovery Current

The P-i-N diode is as important as insulated gate bipolar translators in power electronic devices, and its junction temperature is a significant indicator when evaluating the reliability of power electronics. Thus, an online junction temperature monitoring method with the maximum recovery current for P-i-N diodes is proposed in this article. First, the relationship among maximum recovery current, on-state current, and junction temperature of the diode has been deduced in theory. The linear correlation among the maximum recovery current, temperature, and on-state current has been illustrated. Second, a sampling circuit based on a current transformer has been designed. And then, the mathematical model of junction temperature online monitoring based on the maximum recovery current and sampling circuit has been obtained. Finally, the experimental platform based on the DSP TMS320F28335 has been developed. The experimental results verify the correctness of the relationship among maximum recovery current, on-state current and junction temperature of the diode, and high accuracy of the proposed online monitoring method in practice application, where the maximum temperature error and error percentage are 4.7 °C and 4.49%, respectively. In addition, the proposed method has advantages of simplicity, small size, low cost, convenient installation, and high linearity.