PWM rectifier with reactive power generator function and its control method

Abstract

The invention discloses a PWM rectifier with a reactive power generator function and a control method thereof. The PWM rectifier includes a PWM rectifier main circuit, a PWM rectifier controller, an input current sensor, an input filter, a DC side filter capacitor, an output voltage sensor, a grid voltage sensor, a grid current sensor, and an output voltage sensor. The control method includes: PWM rectifier active and reactive power detection, DC voltage control, rectifier active current and reactive current decoupling control, reactive power compensation control, and active power control. Through the control method of the present invention, the PWM rectifier can control the reactive power of the public access point of the power grid where it is located when the load is low and the DC voltage meets the requirements; when there is no load, it can be used as a static var generator ( SVG); when its load is a battery or other energy storage device, it can also feed energy to the grid side, thereby comprehensively improving the utilization rate of the PWM rectifier and improving the comprehensive economic benefits of the PWM rectifier.

Description

technical field [0001] Embodiments of the present invention relate to the field of rectifiers, in particular, to a PWM rectifier with a reactive power generator function and a control method thereof. Background technique [0002] With the continuous development of the new energy vehicle industry and the advancement of electric drive vehicle technology, electric vehicle chargers are constantly being promoted and applied. But the current charger has many problems. [0003] First, electric vehicles need a large number of charging piles for charging. However, traditional diode rectifiers not only cannot control the voltage and current at each charging stage, but also generate a large number of harmonics and reactive power. [0004] Second, in order to better control the charging process, the current common practice is to introduce a PWM rectifier, which uses a fully-controlled device. The charging process needs to control the charging voltage, current or power, but the capacit...

AI Technical Summary

Problems solved by technology

The charging process needs to control the charging voltage, current or power, but the capacity utilization rate of the PWM rectifier is not high, and most of the remaining capacity is idle

When not charging, the PWM rectifier is idle, which wastes a lot of converter capacity

[0005] Third, there are a large number of electrical equipment that generate reactive power and harmonics in the grid power supply system, and these reactive power and harmonics will degrade the power quality of the power supply system

However, since the PWM rectifier does not work at full power all the time, especially in applications such as inverters or DC chargers, the load changes relatively large

Taking the charging rectifier as an example, at the beginning of charging, the charging current or charging power is very large, requiring a large rectifier capacity, but as the charging process continues, the power and current on the DC side of the PWM rectifier will gradually decrease, which means The capacity of the grid-connected rectifier has not been well utilized, and the PWM rectifier is in a low-load state; when the battery is fully charged or the load power is small, the PWM rectifier is in a no-load state; when the battery or load is cut off, the PWM rectifier is completely idle state, although it is connected to the power grid, it does not play any role; what’s more, when the grid lacks active power, the ordinary PWM rectifier connected to the battery or other devices that can generate electric energy on the DC side cannot return the active power into the grid

[0007] Therefore, in the control and application methods of the PWM rectifier aimed at power control, the surplus capacity of the PWM rectifier cannot be well utilized, so how to make good use of the idle surplus capacity of the PWM rectifier to improve the power environment will have very practical significance and social benefits

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