Indirect Matrix Converter Active Filter Harmonic Reduction
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Solution Overview
Problem
Conventional isolated AC/DC electric power converters have reduced system efficiency due to their three-stage configuration, which also results in low power density and shortened service life due to the need for bulky DC capacitors.
Innovation Solution
A two-stage isolated AC/DC electric power conversion apparatus using an indirect matrix converter and an active filter, eliminating the need for bulky DC capacitors and improving efficiency by reducing harmonic components, thereby increasing power density and extending service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a three-stage configuration is used in isolated AC/DC electric power converters, then the conversion process can be completed with traditional rectification and isolation, but the system efficiency is reduced due to multiple conversion stages
Solution Approach 1:
The patent combines the rectification stage and isolation stage into a single integrated AC/DC converter stage. The indirect matrix converter performs both functions simultaneously, eliminating the need for separate rectification and isolation stages. This merging of functions reduces the total number of conversion stages from three to two, thereby reducing cumulative energy losses and improving overall system efficiency.
Solution Approach 2:
The patent extracts and eliminates the bulky DC storage capacitor from the system by using an active filter circuit instead. The active filter performs the energy storage and smoothing function that traditionally required large capacitors, allowing the removal of the large DC capacitor while maintaining stable output. This extraction of the capacitor function enables higher power density without sacrificing efficiency.
2Quantity of substance
If bulky DC capacitors are used for energy storage in isolated AC/DC converters, then the energy storage requirement is met, but the power density is reduced and service life is shortened
Solution Approach 1:
The patent replaces the traditional passive energy storage mechanism (bulky DC capacitors) with an active energy management system using the indirect matrix converter and active filter. The matrix converter's switching mechanism actively manages energy transfer and storage, eliminating the need for large passive capacitor banks. This substitution of active electronic control for passive energy storage components dramatically reduces volume while maintaining adequate energy storage capacity.
Solution Approach 2:
The patent changes the operating parameters of the converter system by using high-frequency switching in the indirect matrix converter. This high-frequency operation allows for significantly reduced energy storage component sizes while maintaining the same energy storage capacity. The active filter operates at optimized frequencies that enable compact design, transforming the physical dimensions of energy storage requirements without sacrificing functional capacity.
3Reliability
If a three-stage converter configuration is used, then the conversion process is traditional and proven, but the service life is reduced due to the presence of large DC capacitors
Solution Approach 1:
The patent replaces the expensive, large, and limited-life DC storage capacitors with a more reliable active filter circuit using smaller, more durable components. The active filter uses switching devices and smaller energy storage elements that have longer operational lifetimes and higher reliability. By eliminating the large DC capacitor—the component with the shortest service life—the overall system reliability and service life are significantly extended.
4Power
If traditional rectification with large DC capacitors is used, then the AC to DC conversion is achieved, but harmonic components in the output signal increase
Solution Approach 1:
The patent implements an active filter circuit with feedback control that actively monitors and compensates for harmonic components in the output signal. The feedback mechanism detects harmonic distortion and adjusts the switching control of the indirect matrix converter to minimize harmonics. This closed-loop control ensures that the conversion capability is maintained while actively reducing harmful harmonic components in the output, improving power quality without sacrificing conversion performance.
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 two-stage approach enhances conversion efficiency, increases power density, and extends the service life of the converter by eliminating the need for bulky DC capacitors and effectively reducing harmonic components in the output signal.
Implementation Method 1
a transformer having a primary winding and an electrically isolated and magnetically coupled secondary winding
Implementation Method 2
an active filter coupled to the output node and configured to reduce the second harmonic AC component
Data Source
AI summary
A single-phase AC/DC electric power conversion apparatus includes an indirect matrix converter having an input interface to receive a first alternating current (AC) signal and an output interface to produce a second AC signal, where the first AC signal has a grid frequency. A transformer has a primary winding and an electrically isolated and magnetically coupled secondary winding. A coupling inductor is connected in series between the output interface of the indirect matrix converter and the primary winding. An H-bridge switching arrangement is connected to the secondary winding and produces an output signal having a DC component and at least one AC component. The at least one AC component has a second order harmonic of the grid frequency. An active filter reduces the second order harmonic AC component. A modular conversion apparatus for three-phase power replicates the single-phase apparatus as a module for each phase and omits the active filter.