Development of Charging System for bZ4X

Abstract

<div class="section abstract"><div class="htmlview paragraph">In 2022, Toyota launched new battery electric vehicle (BEV), the Toyota bZ4X. Unlike gasoline-powered vehicles, BEVs require charging. Users want increased range and shorter charging times. bZ4X's charging system increased range and shortened AC/DC charging time compared to the Lexus UX300e launched in 2020. A new unit called Electricity Supply Unit (ESU) was developed that integrated a DCDC converter, on-board charger, DC relays, and a branch box for power distribution function into a single unit. The design moved the branch box out of the battery pack to make room for the battery capacity, and it integrated the power conversion function into a single unit, making it more compact than if each unit were mounted separately. A 7 kW or 11 kW on-board charger is included with the vehicle. The 7 kW on-board charger is inside ESU; the 11 kW charger is external to the ESU. By building separate on-board chargers for easier integration, this allowed the ESU and peripheral components to be standardized. Each ESU unit supports a DC charging system with a maximum DC charging power of approximately 150 kW (maximum 400 A). Measures were taken against heat generated by DC relays due to the increased current, and a maximum 400 A charging with indirect water-cooling was achieved. A new protector was developed to fix the DC inlet wire harness(W/H) which is 70 mm² for 400 A. With these developments, increased range and shortened AC/DC charging time was achieved.</div></div>