Control Method of Modular Multilevel Converter for Pure Electric Vehicles

Abstract

The invention relates to a control method for a modular multilevel converter of a pure electric vehicle, which belongs to the technical field of control. The purpose of the present invention is to design a layered controller to control the control method of the pure electric vehicle modular multilevel converter mainly aiming at the control problem of the special modular multilevel converter used for driving the pure electric vehicle. The steps of the invention are: (1) building a mathematical model of a modular multilevel converter; (2) designing a control objective function of a finite set predictive controller; (3) optimizing and solving a multi-step finite set predictive control screening algorithm. The present invention considers the optimal and suboptimal situations at the same time; there are also some studies that consider this situation, but consider all switch combinations in the next time domain, while the present invention only takes the optimal and suboptimal and their left and right levels as backups. option to further reduce the computational burden.

Description

technical field [0001] The invention belongs to the technical field of control. Background technique [0002] Electric vehicles (BEVs) have developed rapidly in recent years, but there are still many key issues to be solved that restrict them from replacing traditional vehicles, such as short battery life and long charging time. Because of this, research on improving battery performance is booming. The battery cells of BEVs usually need to meet the requirements of the converter to drive the motor. However, due to the differences in the chemical characteristics of the battery cells, the voltage imbalance will occur during charging and discharging, which will continuously bring damage to the battery and will Reduced battery life. For high-power electric transmission applications such as electric vehicle traction, the high-voltage power electronic converter can not only improve the speed regulation performance of the system, but also improve the efficiency of power conversion...

AI Technical Summary

Problems solved by technology

[0003] 1. Traditional electric vehicles need a common three-phase two-level inverter with a battery management unit for motor drive and battery control, which requires a lot of hardware

[0004] 2. The existing predictive control of modular multilevel converters is usually only one-step prediction, which does not really reflect the optimal solution characteristics of predictive control

[0005] 3. The number of sub-modules of the modular multi-level converter is large, and the calculation burden is heavy. For example, for a five-level modular multi-level converter, there are 8 sub-modules on each bridge arm, and among the 8 sub-modules There must be 4 to maintain the "input" state to maintain the DC side voltage as a constant value

If it is a 13-level modular multilevel converter, it needs to calculate For 15 levels, 1550000000 cases need to be calculated. It can be seen that the calculation amount is particularly large. If multi-step prediction is performed, the calculation burden will be increased.

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