Symmetrical Converter Modulation for Common-Mode Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-isolated converters in electric vehicle charging systems face challenges with common-mode leakage currents, which can lead to safety issues and non-compliance with regulatory standards.
Innovation Solution
A modulation technique is introduced that eliminates common-mode leakage current in symmetrical non-isolated converters by controlling pairs of switches to operate in tandem, reducing circuit complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isolation transformers are used to eliminate common-mode leakage current, then safety is improved, but device complexity, weight, and cost increase
Solution Approach 1:
The patent extracts the isolation function from the physical transformer and implements it through control algorithms. The common-mode leakage current elimination is achieved by detecting the leakage current and generating compensating control signals that cancel it out, rather than using a transformer to physically isolate the circuits.
Solution Approach 2:
The patent replaces the mechanical/electrical isolation mechanism (transformer) with an electronic control mechanism. The control system uses sensors to detect common-mode currents and actuators (power electronic switches) to generate compensating currents that eliminate the leakage, substituting physical isolation with active electronic control.
2Reliability
If isolation transformers are used to eliminate common-mode leakage current, then safety is improved, but weight increases
Solution Approach 1:
The patent extracts the isolation function from the physical transformer and implements it through control algorithms. The common-mode leakage current elimination is achieved by detecting the leakage current and generating compensating control signals that cancel it out, rather than using a transformer to physically isolate the circuits.
Solution Approach 2:
The patent replaces the mechanical/electrical isolation mechanism (transformer) with an electronic control mechanism. The control system uses sensors to detect common-mode currents and actuators (power electronic switches) to generate compensating currents that eliminate the leakage, substituting physical isolation with active electronic control.
3Reliability
If isolation transformers are used to eliminate common-mode leakage current, then safety is improved, but cost increases
Solution Approach 1:
The patent extracts the isolation function from the physical transformer and implements it through control algorithms. The common-mode leakage current elimination is achieved by detecting the leakage current and generating compensating control signals that cancel it out, rather than using a transformer to physically isolate the circuits.
Solution Approach 2:
The patent replaces the mechanical/electrical isolation mechanism (transformer) with an electronic control mechanism. The control system uses sensors to detect common-mode currents and actuators (power electronic switches) to generate compensating currents that eliminate the leakage, substituting physical isolation with active electronic control.
4Device complexity
If non-isolated converters are used to reduce circuit complexity, then device complexity is reduced, but common-mode leakage current increases
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the common-mode leakage current and adjusts the control signals to the power electronic switches to minimize the leakage current. The detected leakage current is fed back to the controller, which generates compensating signals to cancel the harmful current.
Solution Approach 2:
The patent introduces a control system as an intermediary between the power electronic switches and the load. This intermediary detects the common-mode leakage current and generates compensating control signals that act as a mediator to eliminate the harmful current while maintaining the non-isolated converter architecture.
Data Source
AI summary
An approach for controlling operation of an electrically symmetrical electric power circuit is described herein to reduce common mode leakage currents. The approach can include, for example, a controller circuit configured to control a plurality of switches of the electrically symmetrical electric power circuit, such that one or more electrically symmetrical pairs of switches of the plurality of switches are operated at a same operational state when the power circuit is coupled to an electrical grid to reduce the common mode leakage current. A variant is also described that is adapted for current ripple and overall THD distortion reduction, which can be useful for vehicle to grid power transfer situations.