OBC charger

1. What is an OBC charger?

A device that converts alternating current to direct current.

On board charger (OBC) is an electronic device that converts alternating current from the power grid into direct current suitable for vehicle battery packs. It is mainly used for charging high-voltage battery packs of pure electric vehicles (BEVs) or plug-in hybrid electric vehicles (PHEVs). OBC transmits voltage through AC charging stations and AC charging ports to charge electric vehicle batteries.

2. Working principle of OBC Charger

The car charger inputs AC power and outputs DC power directly to charge the power battery. It usually uses high-frequency switching power supply technology to convert 220V AC power into high-voltage DC power. In addition, the car charger also has various protection functions, such as overvoltage, undervoltage, overcurrent, undercurrent and other measures. When the system encounters abnormalities, the power supply will be cut off in a timely manner.

The working principle of OBC mainly includes two core parts: AC to DC (AC/DC) conversion and direct current DC (DC/DC) conversion.

Firstly, the AC power in the grid is filtered out of noise and interference through EMI filtering circuits, and then converted into DC power through AC/DC converters.The converted DC power is then filtered to remove voltage ripple and obtain stable DC power.

Next, adjust the voltage and current by switching the power supply to meet the needs of battery charging.This process may include power factor correction (PFC) circuits to improve power efficiency and reduce energy loss.

3. Technical specifications and standards for OBC Charger

Modern car chargers are usually isolated to ensure electrical safety. The OBC on national standard electric vehicles must comply with the standard specifications of 《QCT 895-2011 Conductive On Board Chargers for Electric Vehicles》. The power range of car chargers is wide, with common powers including 1.2KW, 1.5KW, 3.3KW, 6.6KW, 11KW, 22KW, etc., which can meet different vehicle models and charging needs.

4. Structure of OBC Charger

The internal structure of OBC includes AC input port, power unit, control unit, low-voltage auxiliary unit, and DC output port. The control unit is the core part of OBC, which controls the conversion process of the power unit through switching devices and provides protection functions such as overvoltage, undervoltage, overcurrent, undercurrent and other protection measures.

In addition, OBC also has the function of communicating with the Battery Management System (BMS) to ensure the safety and efficiency of the charging process. BMS monitors the voltage, current, temperature, and connection status of the power battery pack to control and protect the battery. OBC communicates with the vehicle monitoring system through high-speed CAN network, uploads working status and fault information, and accepts control commands to start or stop charging.

5. Application scenarios of OBC Charger

OBC Charger is mainly suitable for scenarios that require slow charging, such as home or public AC charging stations. Unlike DC charging stations, DC charging stations are suitable for scenarios that require fast charging, such as highway service areas. The use of car chargers ensures that electric vehicles can be safely and conveniently charged in environments such as homes and workplaces.

In practical applications, OBC is not only used for charging the power battery of electric vehicles, but can also invert the DC power of the power battery into AC power through the inverter function, achieving the function of supplying power to external loads (V2L) of the vehicle, or used as an emergency power source for households during power outages.