Method for controlling boost-buck of motor driving Z-source inverter of electric automobile

Abstract

The invention relates to the field of inverters, and relates to a method for controlling the boost-buck of a Z-source inverter of an electric automobile. The method comprises the steps of determining a required motor line voltage reference value by acquiring information, judging whether a straight-through signal is added to the system or not, and obtaining a corresponding modulation coefficient reference value and a corresponding straight-through duty ratio reference value, then adjusting the modulation coefficient and the straight-through duty ratio in a stepping way until the optimal modulation signal is reached to lead the system to reach the optimum, thereby solving the problems that the power supply voltage of a storage battery of the electric automobile is unstable, the energy conversion efficiency of the existing boosting solution is low, and the performance of a motor driving system is influenced or the problem of large inverter loss because the voltage requirement is not regulated and controlled according to different operating conditions of the electric automobile. The voltage can be boosted and reduced by using a quasi-Z-source inverter according to different requirements of the vehicle for the AC output voltage of the driving system under different operating conditions, and an optimal control method meeting the voltage requirements of the operating conditions is provided, so that the performance and efficiency of the driving system are optimally regulated and controlled.

Description

technical field [0001] The invention relates to the technical field of inverters, in particular to a buck-boost control method for a Z-source inverter used for driving an electric vehicle motor. Background technique [0002] The speed range of electric vehicle driving motor is very wide, which requires the power supply voltage of the motor to vary in a wide range. Moreover, when the electric vehicle is in frequent starting, accelerating and overtaking conditions, the battery will be discharged with a large current instantaneously, causing the battery output terminal voltage (drive system input voltage) to fluctuate sharply, and the battery terminal voltage will also decrease with the remaining battery power. Therefore, the fluctuation and gradual drop of the battery supply voltage bring great challenges to the motor drive system and will deteriorate the operating performance of electric vehicles. In order to solve these problems, there are currently two main solutions. One ...

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Problems solved by technology

However, the two-level structure of Solution 1 makes the energy conversion efficiency low. At the same time, in order to prevent the upper and lower bridge arms of the inverter bridge from being "through" and damage the power module, a dead time is usually added, which will cause distortion of the output current and affect the driving of electric vehicles. Performance; in Scheme 2, electric vehicles have different requirements for DC bus voltage under different working conditions, and the control relationship between different operating conditions of the vehicle and the output voltage of the Z-source converter is not given, nor is it given how to realize buck-boost The optimal control method will make the current ripple amplitude increase, the device voltage and current stress will be large, and the inverter loss will be large

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