Integrated drive circuit-based sinusoidal current self-heating method and optimization for Li-Ion batteries

The AC internal heating is recognized as an effective method to overcome the performance deterioration of lithium-ion battery (LiB) at low temperatures while minimizing damage to battery life. The integrated onboard battery self-heater leverages electric vehicle (EV) drive circuitry and electric machine (EM) to achieve internal heating of the battery, saving cabin space and reducing costs. This paper proposes a new method for the internal heating of lithium-ion batteries using sinusoidal AC. The electromagnetic torque caused by the heating current can be inherently eliminated independently of the rotor position. To verify the effectiveness of this method, an electro-thermal model of the LiB integrated with an optimal heating strategy based on Non-dominated Sorting Genetic Algorithm II is established. Groups of tests are designed to evaluate the model's accuracy at different current amplitudes, frequencies, and battery states of charge (SOC). The effectiveness of the optimal heating strategy, considering the current-through capability of the inverter, is also validated. The calculated temperature, voltage, and energy consumption show high fidelity with the test results. Within the temperature range of −30 °C to 0 °C, the proposed method with the optimal heating strategy achieves an average rate of temperature rise (RTR) up to 4.76 °C/min. The energy consumption rate is only 0.2 %/°C.