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Technology File - Safety Technology

Power Control Unit

The brain of the fuel cell vehicle, expertly controlling electricity.

The power control unit converts AC/DC power and appropriately adjusts the electrical voltage. The Mirai power control unit consists of an inverter, a boost converter, and a DC/DC converter. The unit precisely controls the FC stack output and battery charging and discharging under all operating conditions.

The same power control unit is used in hybrid vehicles and plug-in hybrid vehicles.

Power Control Unit


Converting electricity and supplying it from the FC stack and battery to the motor.

Motors cannot be operated by connecting them directly to the battery. The inverter converts DC supplied from the battery to AC to turn the electric motors. Conversely, it converts AC generated by the electric motors during deceleration into DC to recharge the battery. Dual side cooling, which directly cools power elements, improves cooling efficiency and enables inverter downsizing and weight reduction.

Boost converter

Controlling voltage and boosting low voltages.

The boost converter controls charging and discharging electricity by adjusting the voltage of the battery. It steplessly increases the normal roughly 250 V DC supply voltage to a maximum of 650 V DC as required. This means more power can be generated from a small current to bring out high performance from the high output motors, enhancing overall power control unit efficiency.

DC/DC converter

Steps down voltage precisely, enabling electricity to be used for applications other than driving.

The DC/DC converter steps down the supply voltage from the high voltage battery. It steps down the roughly 250 V DC supply voltage from the battery to 12 V DC, to be used by engine auxiliary systems which assist with FC system operation and electronic devices such as headlights.

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Specifications may differ depending on country, region, or model.