Converter Bridge Forced Commutation Reduces Current Ripple
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Solution Overview
Problem
Electrochemical processes like electrolysis and electrodialysis face inefficiencies due to high resistive power losses and current ripples in direct current supply, which degrade equipment and limit operational ranges.
Innovation Solution
A system with a converter bridge and serial inductors that uses bi-directional controllable switches for forced commutation, reducing current ripples and controlling power factor in the direct current supply to electrochemical reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If thyristor bridge rectifiers are used for AC to DC conversion, then high efficiency and high current-handling capability are achieved, but current ripple is generated which causes resistive power losses and equipment degradation
Solution Approach 1:
The patent introduces an intermediary DC-DC converter stage between the thyristor bridge rectifier and the electrochemical reactor. This converter acts as a mediator that decouples the rectifier's current ripple from the reactor, allowing the rectifier to operate at high power while the converter smooths the current before it reaches the reactor, thereby reducing resistive power losses.
Solution Approach 2:
The power conversion system is segmented into two independent stages: a thyristor bridge rectifier for high-power AC-DC conversion and a DC-DC converter for current smoothing and regulation. This segmentation allows each stage to be optimized for its specific function, maintaining high current-handling capability while minimizing current ripple and associated energy losses.
2Device complexity
If current ripple is present in DC supply, then the system can operate with simple rectification, but equipment degradation accelerates and safe operating range is limited
Solution Approach 1:
A DC-DC converter is introduced as an intermediary device between the simple thyristor rectifier and the electrochemical reactor. This mediator smooths the current ripple while allowing the rectifier to remain simple, and protects the reactor from ripple-induced degradation, thereby extending equipment life without significantly increasing system complexity.
Solution Approach 2:
The DC-DC converter performs preliminary action by smoothing the current before it reaches the electrochemical reactor. This pre-conditioning of the current prevents equipment degradation and expands the safe operating range, allowing the system to maintain reliability while using simple rectification hardware.
3Loss of energy
If current ripple is reduced to minimize resistive losses, then energy efficiency improves, but system complexity increases
Solution Approach 1:
The power conversion system is divided into two functional segments: a simple thyristor bridge rectifier for bulk power conversion and a controlled DC-DC converter for current smoothing. This segmentation concentrates the complexity in a dedicated current-regulation stage while keeping the main power conversion stage simple and efficient, minimizing overall energy losses.
Solution Approach 2:
The DC-DC converter serves as an intermediary that handles the complex current-smoothing function, allowing the main rectifier to remain simple. This mediator absorbs the system complexity required for low resistive losses, enabling energy-efficient operation without requiring the entire system to be overly complex.
4Reliability
If thyristor rectifiers with natural commutation are used, then high reliability is achieved, but current ripple with specific frequency components is generated
Solution Approach 1:
A controlled DC-DC converter is introduced as an intermediary between the reliable thyristor rectifier and the electrochemical reactor. This mediator filters out the harmful current ripple components generated by the rectifier's natural commutation, allowing the rectifier to maintain its high reliability while preventing ripple from reaching and affecting the reactor.
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
This approach minimizes resistive power losses and enhances the quality of direct current, broadening the safe and energy-efficient operating range of electrochemical processes.
Implementation Method 1
A system with a converter bridge and serial inductors that uses bi-directional controllable switches for forced commutation, reducing current ripples and controlling power factor in the direct current supply to electrochemical reactors.
Implementation Method 2
A system with a converter bridge and serial inductors that uses bi-directional controllable switches for forced commutation, reducing current ripples and controlling power factor in the direct current supply to electrochemical reactors.
Implementation Method 3
An electrochemical process where electric power is supplied to process fluid can be for example an electrolysis process or an electrodialysis process.
Data Source
AI summary
A system for an electrochemical process includes an electrochemical reactor, a converter bridge for supplying direct current to electrodes of the electrochemical reactor, and serial inductors connected to alternating voltage terminals of the converter bridge. The converter bridge includes bi-directional controllable switches between the alternating voltage terminals and direct voltage terminals of the converter bridge. Forced commutation of the bi-directional controllable switches enables reduction of current ripple in the direct current supplied to the electrochemical reactor. The forced commutation enables also to control a power factor of an alternating voltage supply of the system.