Research on Thermal Control of High Voltage Electronic Control System in Dual Hybrid Vehicles 2024-01-2400

The hybrid system's thermal strategy is centered around controlling the cooling of the motor, inverter, DCDC and evaporator. In this electric drive circuit system, the water temperature sensor is positioned at the radiator outlet rather than within it. Consequently, when determining the required air volume for radiator cooling and water demand for sub-components of the electric drive circuit, an estimation of the inlet water temperature becomes necessary. This estimation relies on a heat transfer formula that converts heat released by circuit sub-components into their contribution to temperature rise within the circuit plus the outlet temperature from the previous round through the radiator to determine inlet water temperature. The inverter's heat transfer power depends on voltage and current levels. Adjusting motor torque leads to rapid changes in current flow while maintaining a low speed for optimal flow rate through the electric drive pump. As a result, there should be a significant increase in cooling liquid temperature passing through the inverter. To ensure accurate signal tracking without any signal noise or interference (signal burrs), it is important to compare estimated temperatures with actual temperatures during this process. In our existing system design, we calculate separate flow demands for motor flow, DCDC flow, OBC flow, and radiator flow. Once these individual flows reach their maximum limits after considering hardware limitations and compensations calculated by HVG inverter, DCDC converter and OBC request level; they are combined together as requested flows using wave filtering techniques. Finally, the desired pump speed is determined based on both requested flow rate and electric drive water temperature by referencing lookup tables. The compressor speed request incorporates feedforward control along with PID control algorithms. Its value depends on both battery cooling requirements and evaporator cooling needs.