Core Technologies and Infrastructure of Electrical Vehicles: A Comprehensive Overview

New energy vehicles, also called alternative fuel vehicles, use unconventional fuels or new power devices alongside conventional fuels. They integrate advanced power control and drive system technologies, resulting in vehicles with advanced features and new structures. New energy vehicles include five major types: hybrid electric vehicles (HEV), pure electric vehicles (BEV, including solar vehicles), fuel cell electric vehicles (FCEV), range-extended electric vehicles (REEV), and other new energy electric vehicles.

The promotion of new energy vehicles is to cope with the needs of environmental protection and the oil crisis, which require the reduction or abandonment of mainstream models that burn traditional gasoline or diesel-driven internal combustion engines.

2. VCU, MCU, and BMS

The vehicle control unit (VCU), motor controller unit (MCU), and battery management system (BMS) constitute the three most critical core technologies in new energy vehicles. They significantly influence performance, efficiency, reliability, and safety.

2.1 Vehicle Control Unit (VCU)

Vehicle control unit (VCU) is a combination of several electrical components used to control one or some objects to ensure the safe and reliable operation of the controlled equipment. The main functions of the VCU are: automatic control, protection, monitoring and measurement.

The VCU of new energy vehicles mainly consists of sensors, control units, and actuators. The core component is the control unit.

• Signal input device: Using various sensors to collect the signals required by the control system and convert them into electrical signals for transmission to the ECU through lines.

• Electronic control unit (ECU): Provides a reference (base) voltage to each sensor, receives electrical signals input from sensors or other devices, stores, calculates and analyzes the received signals and then issues instructions to the actuating elements.

• Actuating element: A device controlled by the ECU to specifically execute a certain control function.

2.2 Motor Controller Unit (MCU)

Drive motors used in new energy vehicles are different from conventional industrial motors. The drive motor of new energy vehicles usually requires frequent starting/stopping, acceleration/deceleration, high torque at low speed or climbing, low torque at high speed, and a wide speed range. New energy vehicle motors generally use permanent magnet DC motors. According to the energization form of the motor, it can be divided into two categories: brushed motors and brushless motors.

2.3 Battery Management System (BMS)

The items that need to be tested for rechargeable batteries include high-precision current, voltage, internal resistance, temperature, cell voltage difference, SOC, SOH, power insulation withstand voltage, etc.

In addition, the most important aspect is the simulation testing of battery charging and discharging. This involves collecting and analyzing data such as current and voltage during the charging and discharging processes. Based on the overall data, parameters related to the safety performance and lifespan of the battery can be determined, thus confirming whether the battery is qualified. In these tests, the current and voltage waveforms of the power supply need to be monitored in real time in a high-precision power supply test system, and the data requirements in the test generally require high accuracy.

3. Sensor/Shunt

Sensors are widely used in many industries: new energy vehicles, rail transit, photovoltaic energy storage, low-voltage electrical appliances, etc. Common sensor testing items include general inspection, measurement performance, influence quantity, time performance, safety performance, mechanical performance, environmental tolerance, EMC test, etc.

The shunt is a type of current sensor, which is made based on the principle of generating a voltage across the resistor when DC current passes through the resistor.

4. EV Charging Station/EV Charger

Charging stations (Chargers) are devices that replenishes electric energy for electric vehicles and is a type of charging and swapping facility for electric vehicles. According to the classification of the output current provided by the charger, the charger can be divided into two types: AC charger and DC charger.

The testing requirements for chargers usually include type approval evaluation, factory inspection, arrival acceptance, on-site inspection and other scenarios. The test items include metering characteristic testing, communication protocol consistency testing, conductive charging interoperability testing, etc.