A Real-time Estimation System of Semiconductor Temperature Using Electro-thermal Simulation

Abstract

This paper presents a real-time electro-thermal simulation system as a novel method of estimating the junction temperature of power semiconductors in real time. The proposed system consists of a real-time computer, a host computer, and an actual motor drive system consisting of a permanent magnet synchronous motor, a three-phase IGBT inverter, a controller, and an FPGA board.
The authors use an FPGA board with a clock of 50 MHz to measure the output voltage of the inverter, because the sampling rate of the real-time computer (18 kHz) is not fast enough to accurately measure the output voltage of the inverter. The measured output voltage is used to reconstruct the PWM signal in the FPGA board which is then transferred to a real-time computer. The instantaneous power losses and the junction temperatures of the power semiconductors are calculated in the real-time computer in which the thermal circuit network is implemented by using the load current and the reconstructed PWM signal. The simulation results were in very good agreement with the experimental results. Junction temperatures of power semiconductors can be estimated under actual operating conditions using the proposed real-time electro-thermal simulation system.