Auxiliary Converter Circuit for Harmonic Suppression
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Solution Overview
Problem
Existing AC/DC switching converter circuits face challenges in achieving unity power factor, zero total harmonic distortion, and zero electromagnetic interference due to non-linear rectified input currents, especially in high output power applications.
Innovation Solution
An auxiliary converter circuit is introduced, comprising a voltage detector, current sensor, and current compensation circuit that provides positive and negative compensation currents based on voltage changes and input current comparisons to regulate the input current, thereby suppressing harmonic distortion and electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an input capacitor is used in the rectifier circuit, then the circuit operation is simplified, but the input current becomes non-linear causing degraded power factor and increased harmonic distortion
Solution Approach 1:
The patent introduces an auxiliary converter circuit as an intermediary component connected in parallel with the main switching converter. This auxiliary circuit generates compensation current that mediates between the non-linear rectified current and the load current, canceling out harmonic components and enabling the input current to follow the input voltage waveform linearly, thus improving power factor and reducing electromagnetic interference while maintaining circuit simplicity
2Object-generated harmful factors
If the input capacitor is removed and continuous mode switching control is applied, then power factor is improved and harmonic distortion is reduced, but total harmonic distortion and electromagnetic interference remain high in high output power applications
Solution Approach 1:
The patent segments the converter system into two independent parts: a main switching converter that handles the bulk of the high output power conversion, and an auxiliary converter that specifically handles power factor correction and harmonic suppression. This segmentation allows each circuit to be optimized for its specific function, enabling the system to deliver high output power while simultaneously achieving low total harmonic distortion and electromagnetic interference
Data Source
AI summary
An auxiliary converter circuit for regulating an input current to a main switching converter circuit. The auxiliary converter circuit has a voltage detector for determining a change in a voltage across the auxiliary converter circuit, and a current sensor for sensing an input current to the main switching converter circuit. The auxiliary converter circuit also has a current compensation circuit that includes a comparator circuit arranged to compare the sensed input current with a reference current; and a controlled current circuit. The controlled current circuit is arranged to selectively provide a positive compensation current and a negative compensation current to the input current, based on the determined voltage change and the comparison, for suppressing harmonic distortion and electromagnetic interference in the input current.