Mutsumi Kikuchi

Low power and high receiving sensitivity wireless wake-up receiver with 2-stage power-supply control scheme for lithium-ion battery systems

A wireless wake-up receiver for lithium-ion battery systems was developed and evaluated. A 2-stage power-supply control scheme is added to the wake-up receiver for supporting low power, high receiving sensitivity, and short wake-up time simultaneously. When the battery system is in power-down mode, only a voltage detector in the wake-up receiver consumes a current while waiting for a wireless wake-up signal with low current and high receiving sensitivity. When the voltage detector detects the wake-up signal, all circuits in the wake-up receiver operate for detecting the wake-up signal with a short wake-up time. The wake-up receiver consumes only 0.3 μA of the power-down current for -32 dBm of the receiving sensitivity with 11 ms of the wake-up time.

Battery control circuit using non-isolation daisy-chain architecture for a 400V Li-ion battery system of a hybrid electric vehicle

In response to typical issues concerning lithium-ion battery systems for HEVs, a cell-control specialized IC and a scheme for the entire circuit mounting the IC (namely, no isolation and a ldquodaisy-chainrdquo communication architecture) were devised. The circuit was configured with the cell-control specialized ICs with 350 nm, BiDMOS, 50 V/3.3 V analog-digital mixed process. But the circuit can handle the 400 V HEV battery without any isolator between the ICs. As a result of these innovations, significant reductions in size and cost and improvement in reliability was achieved. That is to say, in comparison to a conventional product configured with a microcomputer, optocouplers, and discrete components, the developed IC and architecture achieved an 80% reduction of the board area, 90% reduction of component numbers and a reduced failure rate to 4%.