Virtual Impedance Control for Inductive Power Filtering Systems

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Solution Overview

Problem

Conventional inductive power filtering systems face challenges in effectively suppressing harmonic currents and resonance in industrial rectifier systems, particularly in energy-intensive enterprises, due to high costs, complex manufacturing requirements, and limited damping capabilities for harmonic resonance.

Innovation Solution

A virtual impedance comprehensive control method for inductive power filtering systems, incorporating a novel three-winding inductively filtered rectifier transformer with a passive filtering device and voltage source inverter, which adjusts impedance to achieve zero impedance conditions and enhance harmonic damping and quality factor control, thereby improving filtering performance and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the quality factor (Q) of filtering branches is reduced to lower internal resistance, then filtering performance improves, but manufacturing cost increases tenfold and installed space increases

Engineering Contradiction:

Improvefiltering performanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the impedance parameter from a fixed physical value to a dynamically controllable virtual impedance through control algorithms. By adjusting the virtual impedance parameters software-wise rather than hardware-wise, the system achieves optimal filtering performance without requiring expensive low-resistance components, thus resolving the contradiction between filtering performance and manufacturing cost

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the physical mechanical/electrical impedance adjustment (requiring precise component manufacturing and large conductors) with a virtual control system using algorithms and software. This substitution eliminates the need for expensive low-resistance physical components while maintaining filtering effectiveness, directly addressing the cost-performance contradiction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the cross-sectional area of coil wire is increased to reduce internal resistance, then filtering performance improves, but manufacturing cost and installed space increase

Engineering Contradiction:

Improvefiltering performanceVSAvoidinstalled space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The invention transforms the physical impedance parameter into a virtual controllable parameter through control algorithms. Instead of increasing wire cross-sectional area to reduce resistance, the system uses virtual impedance adjustment to achieve the same filtering effect with standard-sized components, thereby reducing installed space while maintaining performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the physical requirement for large cross-sectional area conductors with a virtual control mechanism. The control system simulates the effect of low impedance through algorithms, eliminating the need for bulky low-resistance conductors and significantly reducing the installed space requirement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If passive power filtering device is used to filter specific order harmonics, then investment cost is reduced, but filtering performance is seriously affected when harmonic source changes dynamically

Engineering Contradiction:

Improveinvestment costVSAvoidfiltering performance under dynamic conditions

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The invention introduces dynamic virtual impedance control that can adapt in real-time to changing harmonic conditions. Unlike fixed passive filters, the virtual impedance parameters are continuously adjusted based on system state and harmonic content, enabling the low-cost system to maintain effective filtering performance under dynamic operating conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention implements feedback control mechanisms that monitor system conditions and harmonic content, then adjust the virtual impedance parameters accordingly. This closed-loop control enables the inexpensive filtering system to automatically adapt to changing harmonic sources and maintain optimal performance, resolving the contradiction between cost and adaptability

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10135329B2Virtual impedance comprehensive control method for inductive power filtering system

Publication Date: 2018.11.20 HUNAN UNIV

AI summary

The disclosure discloses a virtual impedance comprehensive control method for an inductive power filtering (IPF) system. According to the disclosure, harmonic damping control at grid side and zero impedance control of filters are organically combined according to a technical problem which is unsolved and process difficulty in equipment manufacturing in an existing filtering method, so that the problem of performance reduction of passive filtering equipment caused by a change in an impedance parameter of a power grid system is solved on one hand, optimization control over a quality factor of the passive filtering equipment may be implemented to reduce dependence on an equipment production process level on the other hand, a quality factor of the single-tuned filters may meet a design requirement, and an overall filtering characteristic is further improved.