Junction Temperature Calculation for SiC Power Module in Traction Inverter Using Linear Frequency Modulation
Abstract
In this article, we propose a rapid junction temperature (<inline-formula> <tex-math notation="LaTeX">$T_{\mathrm {j}}$ </tex-math></inline-formula>) calculation method for SiC power modules using third harmonic injection pulsewidth modulation (Thi-PWM) control, which is particularly useful for transient <inline-formula> <tex-math notation="LaTeX">$T_{\mathrm {j}}$ </tex-math></inline-formula> evaluation of SiC power modules in electric vehicles (EVs) during speed and torque changing. The phase current and frequency changing process is modeled using a linear frequency modulation (LFM), commonly applied in the radar system. Power loss and <inline-formula> <tex-math notation="LaTeX">$T_{\mathrm {j}}$ </tex-math></inline-formula> of the mission profile are continuously analyzed with phase recursion. This approach enables a more accurate depiction of <inline-formula> <tex-math notation="LaTeX">$T_{\mathrm {j}}$ </tex-math></inline-formula> during changes in operating conditions. Compared with commercial software, the calculation speed of this method is increased by 3821 times, and the data size is decreased by 153 times under the same simulation conditions. Thermal imaging tests were conducted on the black-painted power module, with measurements taken under both motor load and inductive load during steady-state and dynamic operation conditions. The error was less than <inline-formula> <tex-math notation="LaTeX">$3.5~^{\circ }$ </tex-math></inline-formula>C.
