A z-source inverter buck-boost control method for electric vehicle motor drive

Abstract

The invention relates to the field of inverters. The invention relates to a step-down and step-down control method for a Z-source inverter of an electric vehicle. By collecting information, the required reference value of the motor line voltage is determined, and it is determined whether the system has added a through signal, and the corresponding modulation coefficient reference value and the through signal are obtained. Duty cycle reference value, and then adjust the modulation coefficient and direct duty cycle step by step until the optimal modulation signal is reached to make the system optimal. The solution is that the power supply voltage of the electric vehicle battery is unstable and the energy conversion of the existing boost solution The efficiency is low, which affects the performance of the motor drive system, or the voltage demand is not adjusted according to the different working conditions of the electric vehicle, and the inverter loss is large. According to the different operating conditions of the vehicle, the demand for the AC output voltage of the drive system is different. The Z-source inverter can step up and down, and provide an optimal control method that meets the voltage requirements of the operating conditions, so that the performance and efficiency of the drive system can be optimally regulated.

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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