Novel electric vehicle driving system

Abstract

The invention discloses a novel electric vehicle driving system. The system comprises a voltage closed-loop PID regulator, a Z-source inverter and a three-phase motor which are connected in sequence, wherein the voltage closed-loop PID regulator is used for increasing the input voltage of the Z-source inverter and controlling the output voltage of the inverter by adding a direct-connection zero vector when the supply voltage of a direct-current voltage source is too low, and the Z-source inverter is used for converting direct current into alternating current required by the three-phase motor. According to the system, a voltage closed loop is additionally arranged in the electric vehicle driving system while a Z-source network is introduced to increase the input voltage of the inverter and control the output voltage of the inverter by adding the direct-connection zero vector when the supply voltage of a storage battery is too low, so that the output performance of a motor driving system is improved. According to the system, the acceleration performance and power performance of an electric vehicle can be effectively improved, the efficiency of the driving system can be improved, and cost is quite low.

Description

technical field [0001] The invention relates to a power electronic converter, in particular to an electric vehicle drive system. Background technique [0002] With the popularity of the concept of energy saving and environmental protection, the research and development of electric vehicles has entered a stage of rapid development. The introduction of my country's new energy policy has provided policy support for the development of electric vehicles in my country. At present, the driving system of electric vehicles generally adopts the driving scheme of direct power supply and inverter, which can no longer meet the needs of the power performance of electric vehicles. When the electric vehicle is starting, accelerating and other working conditions, the voltage of the battery will drop sharply due to the instantaneous large current discharge, the power supply voltage of the inverter will drop accordingly, and the driving torque of the electric vehicle will drop, resulting in s...

AI Technical Summary

Problems solved by technology

At present, the driving system of electric vehicles generally adopts the driving scheme of direct power supply and inverter, which can no longer meet the needs of the power performance of electric vehicles.

When the electric vehicle is starting, accelerating and other working conditions, the voltage of the battery will drop sharply due to the instantaneous large current discharge, the power supply voltage of the inverter will drop accordingly, and the driving torque of the electric vehicle will drop, resulting in slow acceleration and poor power performance. become worse

Traditional inverters have voltage source and current source inverters, but there are many deficiencies in traditional inverters. The main defects of voltage source inverters are as follows: 1) The upper and lower switching tubes of the same bridge arm are added The dead time causes the distortion of the output voltage; 2) The upper and lower switch tubes of the same bridge arm cannot be connected directly, otherwise it will cause a short circuit on the input side and burn the circuit: 3) The output voltage is always lower than the input voltage, which is actually a BUCK circuit , in order to achieve the driving voltage of the driving motor, it is often necessary to add a step-up transformer on the output side, which increases the complexity of the project

The current source inverter has the following defects: 1) The overlapping time of the switching tube commutation leads to the distortion of the output current; 2) The switching mode of the circuit at any time makes the circuit easily damaged; 3) The output AC voltage is higher than the DC side The bus voltage, so this is equivalent to a BOOST circuit, which leads to the inability to adjust the output voltage smoothly

However, the traditional Z-source inverter also has the following disadvantages due to its own results: 1) The capacitor voltage in the Z-source network is greater than or equal to the input voltage, which leads to a large voltage stress. High-voltage capacitors need to be used, and the transformer volume is too large and the cost High; 2) When the converter starts, the inrush current in the network is very large, and at the same time, resonance occurs between the inductor and the capacitor, which may damage the inverter at any time

Images