A Split-Source Self-Heater for Automotive Batteries Based on Traction Drive Reconfiguration

At cold climates, internally preheating batteries are essential and promising to alleviate the performance degradation of electric vehicles because of its rapid heating speed and uniform temperature distribution. To implement onboard internal battery heating, the integrated self-heater is developed to utilize traction motor drive reconfiguration, thereby eliminating extra expensive high-power converters and bulky passive components. However, previous integrated self-heaters introduce excessive voltage stress on dc-link capacitors, arousing a serious concern on the system reliability and safety. In this article, a split-source self-heater (SSSH) is proposed to reconfigure the battery pack as two series-connected sources, where the heating energy can be alternately exchanged via traction motor windings with reduced capacitor voltage stress. The theoretical model and operation principle of the proposed SSSH are deduced for practical controller design and suppression of annoying noises and vibrations. Based on the model, a supertwisting controller is developed to adjust the heating current and cell voltage regardless of nonlinear uncertainties during self-heating. The downscaled experiments verify that the proposed SSSH can preheat automotive batteries with 4.27 oC/min heating speed and 0.24% state of charge/oC energy consumption rate. The induced torque ripple is reduced by 90%, and the capacitor voltage never exceeds the nominal value during self-heating.