A Bi-Directional Charge-Transfer Circuit for 42V Power System 2002-01-3068

The 14/42V Electrical System Architectures have been the subject of discussions in many technical meetings. Some of the major challenges are: system cost, mixed load handling flexibility, jump start issue, battery service life, and transient voltage under load dump situation. In this paper, a patented, bi-directional, charge-transfer circuit is evaluated against these criteria. Circuit performance is discussed in details. It covers circuit efficiency, battery voltage ripple, and transfer-current ripple, and the effectiveness of balancing the battery voltages under various mixed 12/36V loads. The energy transfer principle between a 14V system and a 42V system is presented to demonstrate the cross jumping and surge-load handling capability. The bi-directional energy transfer capability of the circuit easily keeps the load-dump transient-voltage under the 58V limit with either the 14V or the 28V batteries are disconnected.