ETC is no stranger to car owners. As an advanced road and bridge toll collection method, it is favoured by drivers for its efficient traffic efficiency.

In 2019, my country implemented a number of measures to promote ETC, and the notice required all provinces to achieve an installation rate of more than 80% by the end of 2019.

So what are the components of ETC? Where is the mystery of its ability to achieve fast access?

What is ETC?

Fully automatic toll collection system (ETC, Electronic Toll Collection) is one of the service functions of the intelligent transportation system.

The system performs wireless communication and information between the on-board device installed on the vehicle and the microwave antenna installed on the ETC lane of the toll station exchange.

Using computer networking technology to carry out background settlement processing, so as to achieve the purpose of quickly passing through the road and bridge toll station without stopping.

 The working principle of the ETC system

ETC is mainly composed of an automatic vehicle identification system, central management system and other auxiliary facilities.

Commonly placed on the front windshield of the vehicle is the on-board unit (OBU is the abbreviation of On Board Unit) in the vehicle automatic identification system, which stores the identity information of the vehicle and is the “pass” that each vehicle can pass through the toll booth.

In addition, the automatic vehicle identification system also includes hardware devices such as roadside units (RSU is the abbreviation of Road Side Unit) set outside the toll gate and loop sensors buried under the lane.

RSU is mainly deployed on the gantry of toll station intersections or expressway intersections, and performs card reading and charging for vehicle OBUs.

The information database management system is the “brain” of the ETC system. A large number of registered vehicle and user information are stored in the information database, which matches the vehicle and user information in the onboard unit so that the identity of the incoming vehicle can be accurately determined.

Other ancillary facilities include lane railings, toll displays, intruder alarms and traffic lights.

In the ETC system, the dedicated short-range communication standard protocol (DSRC) is used for half-duplex communication between the OBU and the RSU.

When the loop sensor senses the vehicle, the OBU and the RSU use the microwave for two-way communication and data exchange;

The central management system obtains vehicle information and issues execution instructions, such as deduction of fees, automatic control of railings or other obstacles, and instructions from traffic display devices The vehicle is moving.

Application of power module in ETC equipment

Due to the limitations of the operating environment of the ETC system, the application of power modules often encounters the following difficulties:

1. Since ETC equipment mainly works in harsh outdoor conditions, the temperature during the day is high, and the operating temperature of the equipment must meet the requirements of 85 °C;

The front-end main power supply (AC/DC) is currently debated in a large range to ensure that it can meet the requirements of high-temperature conditions.

2. The outdoor power grid fluctuates greatly. For the front-end power supply, the input voltage will rise or fall for a short time. It must meet the 300VAC surge input for 5s without damaging the design;

3. Higher requirements for EMS indicators such as lightning strike and surge;

4. The outdoor maintenance cost is high, and the reliability of the power supply is high.