Technical Library January 6, 2012

Recent Trends in Quick Chargers for EVs


1. Introduction

Under its company philosophy of contributing to a bright future society by creating valuable products while protecting the environment, Nichicon is working to help solve the serious environmental problem of global warming through the Nichicon Energy Control System Technology (NECST) Project. Inaugurated on March 15, 2010 and under the direct control of President and COO Sachihiko Araki, the NECST project is aimed at achieving a stable supply of energy while still protecting the environment.

Since the Great East Japan Earthquake of March 2011 and the subsequent accidents at the Fukushima Dai-Ichi nuclear reactor, society is more aware than ever of the pressing need to achieve a stable supply of energy while still protecting the environment. This is spurring Nichicon to pick up the pace of developing EV-related equipment and the quick chargers that are the infrastructure for these vehicles. The mass-produced EVs currently available in Japan all use an in-vehicle charger made by Nichicon, and we have utilized our experience and technologies to come out with a lineup of revolutionary ultra-compact quick chargers. Let’s look at EV quick chargers and the technology behind them: in other words, the charging infrastructure for electronic vehicles.


2. Workings and Standards of Quick Chargers

Quick chargers are high-capacity power sources (delivering double-digit kilowatt amounts) that convert alternating current (AC) into direct current (DC) as part of the charging infrastructure. Because these chargers have a high output of 500 volts, a special connector is required when charging cars so that large amounts of current can be safely sent to an EV’s lithium-ion battery. A battery management system (BMS) constantly monitors the state of the in-vehicle lithium-ion battery to ensure safety and reliability; it is the communication between this BMS and the quick charger that allows charging to be carried out safely as shown in. (Figure 1).

A common communication protocol between the BMS and quick charger was developed by Japan’s CHAdeMO (CHArge de MOve) Association, whose members include entities such as automobile manufacturers, electric utilities, and charger manufacturers. CHAdeMO is the de facto standard for rapid charging of currently mass-produced EVs and EVs that Japanese automobile manufacturers are set to release.

The CHAdeMO Association aims to make this an international standard and is lobbying international standardization groups to this end. There are already a number of power supply manufacturers in North America and Europe that are selling quick chargers based on specifications developed by the CHAdeMO Association. And of the quick chargers already installed around the world, an increasing number are made by American, European, and Japanese manufacturers that are CHAdeMO Association members.

Figure 1: How a quick charger works (CHAdeMO standard)

Figure 1: How a quick charger works (CHAdeMO standard)

Source: Compiled by Nichicon based on information from the CHAdeMO Association website.


3. Nichicon Ultra-Compact Quick Charger

All of the OBCs (on board chargers) for EVs currently sold in Japan are from Nichicon. Since these OBCs have much in common with quick chargers, such as the use of battery communication know-how, we were able to make use of these common technologies in developing the world's smallest and lightest 20-kW and 30-kW quick chargers for EVs, which we released in August, 2011. We further expanded our lineup with the December 2011 release of a 50-kW-capacity model that adopts the external dimensions and user friendliness of the previously released products as shown in Figure 2. The most remarkable point of this newly developed power supply is that it occupies approximately 50% less space and weighs about 60% less than the current model, thus saving the customer cost and effort in installing the system. Nichicon was able to come out with this modularized charger offering high reliability and high efficiency by making use of the technologies and components developed through the company’s OBCs.

These are some of the features of Nichicon’s quick chargers.
• A thin, compact design (thin and light) enabling installation in a greater range of locations.
• Highly reliable and efficient thanks to Nichicon’s technological expertise in OBCs.
• Modularized construction means easier maintenance.
• User friendly with large LCD screen and interactive operation.
• All models from 20kW to 50kW have the same external dimensions and design and share common modularization of the internal components.
• Covered by subsidies offered by the Next Generation Vehicle Promotion Centre.

Figure 2 Ultra-compact quickcharger
Figure 2: Ultra-compact quick charger

4. Using a Charger

Using a charger for EVs is incredibly easy, and safe as well. Just insert the DC connector into the car’s inlet and press the button on the charger to start charging. As shown in figure 3, it is similar to filling up a car with gasoline. Most chargers use a mechanism that locks the DC connector and inlet together, so the user only needs to make sure this locking mechanism is engaged before starting charging.

Figure 3 Insertion of the DC connector into the vehicle
Figure 3: Insertion of the DC connector into the vehicle

When the vehicle is completely charged, a signal from the EV stops the charging. The user then follows the on-screen instructions on the charger to remove the DC connector and complete the charging process. If the user does not have enough time to wait for a full charge, the charging process can be stopped at anytime.


5. Conclusion

Although EVs have been called the car of the future, they still cannot compete with gasoline-powered vehicles due to limitations such as prohibitive cost and short driving distances. In recent years however, exhaust-gas-free EVs are coming closer to reality for the average consumer thanks to developments like compact yet high-capacity batteries, small, light OBCs made possible by advances in power electronics, and the ability to charge EVs in the average home. Furthermore, CHAdeMO-compliant quick chargers—the infrastructure that will allow EVs to recharge on the road and travel long distances—are enjoying increasingly widespread use around the world. Using the technologies built up through our OBCs, we have developed ultra-compact quick chargers that occupy approximately 50% less space and weigh about 60% less than our current model and thus reduce installation cost. These ultra-quick chargers are expected to contribute to the spread of EVs and the supporting infrastructure, and subsequently bring us closer to a world in which people can enjoy fewer carbon emissions.


Nichicon Corporation
From the Dempa Shimbun, January 6, 2012

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