CHAdeMO – quick charging method for EV battery

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30/08/2014 Leave a comment

CHAdeMO is the trade name of a quick charging method for battery electric vehicles delivering up to 62.5 kW of high-voltage direct current via a special electrical connector.

It is proposed as a global industry standard by an association of the same name. CHAdeMO is an abbreviation of “CHArge de MOve”, equivalent to “charge for moving”. The name is a pun for O cha demo ikaga desuka in Japanese, translating to English as “How about some tea?”, referring to the time it would take to charge a car.

CHAdeMO can charge low-range electric cars in less than half an hour.

CHAdeMO Association
CHAdeMO was formed by The Tokyo Electric Power Company, Nissan, Mitsubishi and Fuji Heavy Industries (the manufacturer of Subaru vehicles). Toyota later joined as its fifth executive member.

Three of these companies have developed electric vehicles that use TEPCO’s DC connector for quick charging.

DC fast charging
Most electric vehicles (EVs) have an on-board charger that uses a rectifier circuit to transform alternating current from the electrical grid (mains AC) to direct current (DC) suitable for recharging the EV’s battery pack.

Cost and thermal issues limit how much power the rectifier can handle, so beyond around 240 VAC and 75 A it is better for an external charging station to deliver direct current (DC) directly to the vehicle’s battery pack.

Given these limits, most conventional charging solutions are based on either 240V/30A service in the USA and Japan, 240V/70A service in Canada or the 230V/15A or 3Φ400V/32A service in Europe and Australia. (While AC charging systems have been specified with higher limits – SAE J1772-2009 has an option for 240V/80A and VDE-AR-E 2623-2-2 has 3Φ400V/63A – these charging station types have been rarely deployed in the US and only electric vehicles made by Tesla have a matching rectifier.)

For faster charging, dedicated chargers can be built in permanent locations and provided with high-amperage connections to the grid. In this style of connection, the charger’s DC output has no effective limit, theoretical or practical. Such high voltage and high-current charging is called a DC Fast Charge and is also referred to as level-3 charging (in contrast with less powerful AC charging levels 1 & 2).

TEPCO has developed patented technology and a specification for high-voltage (up to 500 VDC) high-current (125 A) automotive fast charging via a JARI DC fast charge connector. It appears this is the basis for the CHAdeMO protocol.

The connector is specified by the JEVS (Japan Electric Vehicle Standard) G105-1993 from the Japan Automobile Research Institute. In addition to carrying power the connector also makes a data connection using the CAN bus protocol.

This performs functions such as a safety interlock to avoid energizing the connector before it’s safe (similar to SAE J1772), transmitting battery parameters to the charging station including when to stop charging, target voltage, and total battery capacity, and while charging how the station should vary its output current.

Vehicle charging
The Chademo quick charge option was promoted by Nissan-Renault and it has found acceptance with Japanese car manufacturers to allow their electric cars to benefit from the Chademo charger network in Japan – this includes models such as Nissan LEAF and the Mitsubishi i MiEV (including its derivates such as Citroën C-ZERO and Peugeot iOn).

The Zero Motorcycles have an option for a Chademo inlet since 2013. Tesla Motors cars require an optional external adapter to charge from a Chademo station. (Teslas have a proprietary “Supercharger” inlet for offboard charging up to 135 kW.)

After the creation of the IEC 62196-3 offboard charger standard, Nissan accepts the option to have the DC charging stations being equipped with both Chademo and Combo outlets. Read more

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