Understanding the role of Onboard Chargers in Electric Vehicles.

On Board Charger

The way electric vehicles have evolved and created a buzz in the automotive market space is exceptional. The automakers and OEMs are focusing on providing safer, more reliable, technologically advanced, long-range electric vehicles. The battery of an electric vehicle, the Battery Management System, and onboard chargers play a critical role in deciding the range and sustainability of an EV on the road.

The time taken to charge a battery is a very important factor to consider while opting for an electric vehicle (whether a Plug-in hybrid electric vehicle or a battery electric vehicle). Unlike a gasoline-powered vehicle, it takes much longer to replenish the battery of an electric vehicle.

In this blog, we will discuss onboard chargers, their architecture, features, benefits, and more. Before moving ahead with the topic it’s necessary to have an overview of EV charging and understand the technology used in EV charging stations and their subsystems.

Electric Vehicle Supply Equipment (EVSE)

Electric Vehicle Supply Equipment (EVSE) constitutes the equipment of an electric vehicle charging station and its subsystems that enables EV charging. The battery pack of the plug-in electric vehicle is charged through the power grid with properly integrated EVSE. The EVSEs or charging stations can be classified into two types:

AC Charging Station:  AC charging stations can further be classified into two types: Level 1 and Level 2 type chargers, which have residential and commercial applications. AC chargers fetch AC power from the power grid and send it to an electric vehicle via an onboard charger (a part of an electric vehicle). Level 2 chargers are slow chargers and take 8-16 hours to fully charge an electric vehicle. The onboard charger receives AC power from the EVSE, which receives the power directly from the grid. The onboard charger converts AC current into DC and charges the EV battery through the battery management system.

DC Charging Station:  DC Charging stations are also called level 3 EV chargers. These chargers are super-fast and can charge an electric vehicle in 30 minutes. At EV charging stations, the DC charger gets AC power directly from the grid and converts it into DC at the station itself.  DC chargers bypass the onboard chargers and feed DC power directly to the EV battery. The output of the DC charger is approx. 600V and current up to 400 A and are used for charging EV fleets.

On-Board Chargers (OBC)

Every customer segment has its unique requirements from EVSEs. The requirements of the EV charging station are diverse in all cases, whether it is residential charging or commercial charging or fleet charging. The setup is unique every time and it depends on the capacity, type, number of charge points, and features required by the setup. On-board chargers in EVs address a very common problem of EV owners. It allows them to charge their vehicle on the availability of AC power. It does not depend on the EV charging station to charge the vehicle.

On-board charger converts AC power from the grid into AC power to charge the EV battery. The attachments with onboard chargers allow EV owners to charge the EV battery at home or from any other charging station.

The on-board charger in electric vehicles comprises of a unit that contains a variety of signal conditioning solutions, integrated high voltage isolation AC-DC converters, AC rectifiers, dual bridgeless power factor correction (PFC), gate drivers, error amplifiers, and many other power electronic components.

Related Blog: EV Range Anxiety: How to Overcome it?

Some of the key features of on-board chargers are:

  • Efficiency: The latest onboard chargers are compatible with global electric standards and can be easily assembled in an electric vehicle. They are highly efficient as they need very little space in a vehicle and reduce the charge time of the EV battery.
  • Power Handling: The onboard chargers can withstand a wide range of input voltages and their power handling capacity varies from 3 kW to 22 kW.
  • Two-way Charging: Two-way on-board charger or bidirectional on-board charger works two ways in an electric vehicle. On one hand, they transmit DC power from EVSEs to a battery of a vehicle, on the other hand, they can be used to send power back to the grid (V2G). The bidirectional onboard charger can also be utilized as a standby source of power for residential applications, and another electric vehicle.

For an electric vehicle, an onboard charger is one of the most important parts. Though it is much slower than the DC fast chargers, it provides great flexibility to charge an EV battery anywhere anytime using AC power source.  

Nowadays, automotive companies are focusing on designing efficient, compact, and light weighted onboard chargers to support EVs to cover longer distances in one charge.