A Global Monitoring Method for Junction Temperature of Power Devices in Motor Drivers Based on On-state Resistance

As a critical indicator of power devices' thermal performance and reliability, accurate junction temperature monitoring is vital for enhancing system safety and thermal management efficiency. Traditional estimation methods, relying on thermocouple measurements or indirect model calculations, suffer from response lag or complex deployment. This paper proposes an improved global junction temperature monitoring method based on on-state resistance. By online extracting the variation characteristics of MOSFET on-state resistance and establishing a thermal coupling model with historical data, the method enables junction temperature estimation for global devices. Compared to traditional approaches, it features higher real-time performance and integrability, adapting to thermal characteristic changes under diverse working states. Experimental verification on a motor driver platform shows the method controls estimation error within ±2°C without additional sensors, demonstrating promising application prospects through its global monitoring capability and thermal coupling model.