Novel instantaneous-current-direct-control-based pulse width modulation current tracking control method

Abstract

The invention discloses a novel instantaneous-current-direct-control-based pulse width modulation current tracking control method, which relates to the field of current tracking control methods for grid-connected inverter equipment in the field of power electronics. When output current regulation is performed in each cycle, an instantaneous voltage value of a direct current side and an instantaneous voltage value of a power grid are sampled, the action of effective instantaneous current vectors of an inverter in different on / off states is analyzed to obtain a control formula for instantaneous current shift factors, the action time of each effective instantaneous current shift factor at a corresponding moment is calculated, and control over the action time of different instantaneous current shift factors is realized in the next regulation cycle in a pulse width modulation way by utilizing functions of a pulse width modulation (PWM) peripheral of a digital signal processor (DSP) chip to finish the shift of a current instantaneous current vector to an instantaneous reference current vector of the next moment, thereby fulfilling the aim of controlling the reference current tracking of output current. The method is convenient to use, simple in operation, quick in current tracking response and low in deviation, and compared with the conventional methods, is highly advanced.

Description

technical field [0001] The invention relates to the technical field of current tracking control methods for grid-connected inverter equipment in the field of modern power electronics, in particular to a novel pulse width modulation current tracking control method based on instantaneous current direct control. Background technique [0002] For inverter devices such as APF (active power filter), SVG (static var generator), photovoltaic and wind power generation inverter grid-connected equipment and other types of inverter devices, the output end is directly connected to the inverter through a series reactor. Connected to the grid, the output terminal voltage is supported by the grid voltage. The function of this type of device is mainly realized by accurately and quickly controlling the output current to track the command current. Different types of grid-connected inverters have different command current generation methods, but after the command current is generated, there is ...

AI Technical Summary

Problems solved by technology

Different types of grid-connected inverters have different command current generation methods, but after the command current is generated, there is a problem of how to effectively control the actual output current to track the command current. This link directly affects the entire set of grid-connected inverters to a large extent. The final performance index of the variable device

Traditional current tracking control methods include typical current hysteresis control, voltage space vector control, and some deformation methods. These traditional methods essentially require the main control system to detect the actual output current in real time and pass the command current. Relatively confirm the switching state of the inverter circuit, which puts forward high requirements on the data processing speed of the main control system of the inverter device. Taking the switching frequency of 20KHZ as an example, the current comparison control frequency of the main control system is required to be at least 40KHZ, that is, every It takes 25us to control the output current once, plus the command current calculation and other necessary data processing required by the device, such a fast speed requirement is difficult to meet even if a high-speed DSP chip is used, and too low switching speed will lead to increased output current deviation, The output current waveform becomes worse, the output reactor increases, the equipment cost increases, and the output current response speed decreases. Therefore, the equipment adopting the traditional current tracking control method improves the current response speed, improves the output current waveform quality, reduces the shunt reactor volume, In terms of weight and other considerations, most of them have to add special circuits or chips to meet the requirements for current regulation speed

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