Design and analysis of hybrid electric vehicle energy flow simulation system

For hybrid electric vehicles, in actual operation, in order to achieve rapid switching between the motor and the engine, the system needs to have a short response time; in order to ensure the stability of the vehicle operation, the system needs to have accurate current positioning; at the same time, in order to ensure The reliability and accuracy of the system control also have high requirements on the system sampling accuracy and control speed. The key to studying the energy flow control strategy of hybrid electric vehicles is to study the relationship between the battery and the electric motor and engine.

In practical work, the hybrid electric vehicle has a complicated working environment and various interference factors have a greater influence, which makes it more difficult to study its energy flow state. Is it possible to simulate and simulate the working performance of power batteries in the laboratory? In this way, not only can a lot of manpower and material resources be saved, but also a good reference for the design and assembly of hybrid electric vehicles.

This article introduces the hybrid electric vehicle energy flow simulation system designed for the above requirements. The system can simulate the actual working environment of the hybrid electric vehicle and provides a flexible, simple, and efficient platform for studying the hybrid electric vehicle control strategy.

System Features

The entire system is built with a combined platform. According to the requirements of the simulation work, the corresponding simulation modules are combined according to the size of the working current to form the energy control part of the entire system. Using this structural design can greatly reduce the volume and power consumption of the entire system.

The system integrates CAN2.0B and RS-232C interfaces, can communicate and exchange data with various control instruments in the car, and is compatible with the standard communication interface of the car master control system, which can be easily transplanted to the actual hybrid electric vehicle system in. At the same time, it can directly communicate with the computer, and the computer can control the operation of the system, which is convenient for monitoring and simulation.

system structure

The hybrid electric vehicle energy flow simulation system is mainly composed of a charging system, a discharging system and a control system. System block diagram shown in Figure 1.

Figure 1 Simulation system structure

In the charging system, high-efficiency pulse width modulation (PWM) is used, and the feedback stability control system is used to make the charging process fast and stable.

In the discharge system, an energy-saving energy feedback method is used to return electrical energy to the grid or still return to the charging system to achieve the purpose of energy saving and consumption reduction.

In the control system, high-speed embedded microprocessor is adopted, which has the characteristics of strong anti-interference ability, fast response speed and flexible control mode.

1 Charging system

First, the power grid voltage is rectified, pulse width modulated, and then transformed by an isolation transformer, and then rectified and stabilized to obtain the required working voltage. In order to ensure the fast and stable charging process, the sampling values ​​of voltage and current are introduced into the stability control system to make the charging process fast and stable. The charging system structure is shown in Figure 2.

Figure 2 Charging system structure

2 Discharge system

The battery discharge system uses energy feedback. First, the power of the power battery is converted and sent to the intermediate buffer, and then the power is converted into three-phase AC by means of inversion. This part of energy can be used to return to the grid, or it can be sent to the charging system again to achieve power The repeated use of the system can effectively reduce the impact of current fluctuations on the power grid. The structure of the discharge system is shown in Figure 3.

Figure 3 Discharge system structure

3 Control system

This system uses a control system based on a high-speed embedded microprocessor. The high-speed processor can ensure the fast completion of the charging and discharging tasks of the power battery, and the digital filtering algorithm makes the system have better anti-interference ability. The high-precision A / D and D / A control units make the charging and discharging process dynamic and stable, meeting the control requirements. The conversion status informs the CPU to read the conversion result in an interrupted manner to ensure the rapid response of the system. The monitoring computer can control the operation of the system through the interface function, and can collect real-time parameters for data analysis, processing and monitoring. The control system structure is shown in Figure 4.

Figure 4 Control system structure