Electric vehicle charging system with high power quality

Abstract

The invention discloses an electric vehicle charging system with high power quality. A direct-current charger of the electric vehicle charging system is an electric vehicle charger on the basis of a voltage type PWM (pulse width modulation) rectifier, and a control system of the PWM rectifier is of a double-closed-loop control structure with a traditional outer PI (proportion integration) regulating voltage loop and an inner dead-beat control current loop. Harmonic current which is injected into a power grid by the electric vehicle charging system is reduced, and the power quality of the power grid is improved. Besides, an inverter link is added to the electric vehicle charging system, so that the electric vehicle charging system can be connected with a battery pack to charge the battery pack or can be connected with an air conditioning load for electric discharge according to load change conditions (namely a peak period, a valley period and the like) of the power grid, energy can flow in positive and negative directions, the electric vehicle charging system can run in a rectification state to receive the energy from a power-grid side, can also run in an inversion state to transmit the energy to the load, and runs in an approximate unity power factor state, and the utilization efficiency of power resources is improved.

Description

technical field [0001] The invention belongs to the field of power distribution systems, in particular to a charging system for electric vehicles with high power quality. Background technique [0002] By the end of 2011, China Southern Power Grid had built 15 charging and swapping stations and 2,953 charging piles in Guangzhou, Shenzhen, Zhuhai, Zhongshan, Nanning, Liuzhou, Guilin, Kunming, Haikou, and Zhaoqing, with a total of about 49,000 charging and swapping times. , The charging and swapping capacity is about 2.44 million kwh. At present, the Guangzhou Racecourse and Science City Electric Vehicle Exchange Station Experience Center projects are under construction as scheduled, which will play a good role in demonstration, guidance and service for the promotion and use of electric vehicles; and the State Grid Corporation has built a total of 111 electric vehicle replacement stations Power stations, 8,930 chargers, and 7,245 AC charging piles, covering 26 provinces and ci...

AI Technical Summary

Problems solved by technology

[0003] However, the currently operating electric vehicle DC charger is composed of power electronic conversion circuits, etc., resulting in harmonic generation and low power factor, which affects the power quality of the grid

Therefore, it is necessary to invest in reactive power compensation devices and filter devices for use together, thereby increasing the floor space and increasing additional capital investment

In addition, the fully charged electric vehicle battery pack is discharged through the discharge resistance load, which cannot effectively use electric energy

Images