H-Bridge Multi-Level Converter Controller for Doubly-Fed Induction Generator
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Solution Overview
Problem
Conventional controllers for doubly-fed induction generators face challenges in controlling high voltage and large-scale systems, including high voltage distortion, limited mounting distance, and inadequate fault ride-through and anti-islanding capabilities, which affect the stability and efficiency of wind, tidal, and wave power generation.
Innovation Solution
A controller using a H-bridge multi-level converter topology with a boost converter, incorporating a control algorithm for fault ride-through, anti-islanding, and grid voltage synchronization, enabling bi-directional power control and reactive power supply, thus addressing the limitations of existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional controller with SCR and capacitor is used for doubly-fed induction generator, then the structure is simple and cost is low, but voltage distortion is high and grid synchronization is inadequate
Solution Approach 1:
The patent changes the fundamental parameters of the controller by transitioning from SCR-based forced coupling to IGBT-based pulse width modulation. This enables precise control of switching timing and duty cycle, achieving both simple structure and reliable grid synchronization through parameter optimization rather than complex hardware architecture.
Solution Approach 2:
The patent replaces the mechanical/electrical forced coupling method (SCR) with an electronic control method (IGBT PWM). This substitution eliminates the need for mechanical synchronization mechanisms while achieving superior grid synchronization through electronic timing control, resolving the contradiction between structural simplicity and synchronization reliability.
2Length of moving object
If the mounting distance between controller and generator is increased, then the installation flexibility is improved, but voltage distortion increases and grid synchronization deteriorates
Solution Approach 1:
The patent introduces an intermediary synchronization mechanism that actively compensates for the effects of mounting distance. The controller uses phase-locked loop technology and adaptive timing adjustment to maintain voltage synchronization regardless of distance, allowing increased installation flexibility without sacrificing synchronization reliability.
3Device complexity
If a simple controller structure is used, then the cost is reduced, but fault ride-through capability and anti-islanding function are insufficient
Solution Approach 1:
The patent implements a universal controller architecture based on IGBT PWM technology that performs multiple functions including fault detection, ride-through capability, anti-islanding protection, and grid synchronization. This multi-functional approach achieves high adaptability without proportionally increasing structural complexity, as the same core technology serves multiple protective and control functions.
4Loss of energy
If conventional low voltage driving is used, then the unit cost of generation is reduced, but the generator voltage cannot meet large-scale system requirements of not less than 600V
Solution Approach 1:
The patent implements dynamic voltage control through IGBT PWM switching, allowing the generator to adapt its output voltage according to system requirements. The controller dynamically adjusts switching frequency and duty cycle to maintain optimal performance across a range of voltages, enabling the system to meet large-scale voltage requirements (≥600V) while maintaining cost efficiency through flexible operational control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively controls high voltage and large-scale doubly-fed induction generators, reducing voltage distortion, enhancing stability, and ensuring reliable grid synchronization, even during short interruptions, while extending the mounting distance and improving energy regeneration efficiency.
Implementation Method 1
doubly-fed induction generator
Implementation Method 2
boost converter
Data Source
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AI summary
Disclosed is a controller of a grid coupled type doubly-fed induction generator having a multi-level converter topology, which can control the doubly-fed induction generator having a high voltage specification and can perform a fault ride-through function, an anti-islanding function and a grid voltage synchronization function required for a dispersed power generation facility. The controller makes a H-bridge multi-level converter generate a three-phase voltage waveform resulted from the structure that single-phase converters each being composed of a 2-leg IGBT are stacked in a serial manner, and controls a rotor current so as to make the rotor coil of the doubly-fed induction generator in charge of a slip power only. The boost converter is composed of a 3-leg IGBT and a boost inductor generating a direct current voltage of its source required for the H-bridge multi-level converter.