Flexible High Voltage Architecture for Commercial Hybrid Vehicles

Architecting and integrating commercial hybrid electric vehicles (HEV) is a long and labor intensive process which is unique every time. The challenge intensifies when one attempts to create an HEV capable of engine-off operation. In this case, electrical power needs to be supplied to devices which are normally powered by the engine accessory belt. These devices are referred to as e-accessories. To address the issue of time to market and reduce vehicle integration burden, a plug-and-play architecture for connecting e-accessories has been developed. The Flexible High Voltage DC System is analogous to a USB hub on a PC and serves to provide power, control and communication to e-accessories such as electrified power steering, electrified brakes and electrified HVAC. The system performs several key functions: 1) it delivers power to devices according to their demand; 2) if demand exceeds supply, it limits power according to priority (safety critical = highest priority) and 3) it is capable of isolating device failures without affecting remaining devices. The system also provides pre-charge and contactor diagnostic capabilities. This approach has been demonstrated on a number of experimental vehicles and has been put in limited production. The paper will cover design development approach starting with Voice of the Customer, stakeholder needs analysis, prototype development, approach to interface standardization and will conclude with prototype testing and results.