Design and Implementation of a Distributed Thermal Control System for Power Electronics Components in Hybrid and Electric Vehicles 2019-01-0501
Hybrid electric vehicles and all-electric vehicles use power electronic (PE) devices to convert between high voltage DC power of the battery and other formats of power. These PE components require operation within a certain temperature range, otherwise, overheating can potentially cause component as well as vehicle performance degradation. Due to this degradation concern, a thermal management system is required for PE components. This paper focuses on the design and development of a PE components’ thermal control system. The proposed control system is a distributed thermal control system in which all the PE components are placed in series within one cooling loop. The advantage of the proposed control system is its reduced system complexity, energy efficiency and flexibility to add future PE components. In addition, electronic control units (ECUs) are utilized so that complex control algorithms can be implemented. From a theoretical perspective, the proposed control system is proven to have sufficient thermal capacity under extreme hot ambient environments. The proposed control system is implemented and tested in various conditions. Test results show that the maximum coolant temperature reached is 73.71°C which further verifies that the proposed thermal control system has sufficient thermal capacity. In testing, it has been found that residual heat accumulated around PE components after the propulsion system becomes inactive and the heat generated during off power mode charging can cause a coolant after-boil issue. Therefore, adaptive after-run cooling control and off-power mode cooling are designed correspondingly to cover those conditions when the vehicle propulsion system is inactive.