Parallel AC-DC Converter Carrier Synchronization via CAN Bus
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Solution Overview
Problem
Non-isolated AC-DC conversion apparatuses in vehicle charging devices experience circulating currents when connected in parallel, leading to increased losses and decreased efficiency, affecting the stability of the charging system.
Innovation Solution
A power conversion apparatus with an AC-DC conversion circuit and a circulating current controller that synchronizes carriers between parallel-connected units via a CAN bus, suppressing high-frequency circulating currents without additional hardware, thus enhancing efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple non-isolated AC-DC conversion apparatuses are connected in parallel to improve power conversion capability, then the alternating current-direct current power conversion capability is improved, but circulating current is generated between the apparatuses
Solution Approach 1:
The patent implements a feedback mechanism where the first circulating current controller detects circulating current and generates a compensation amount based on the detected value. This compensation amount is fed back to adjust the drive signal, creating a closed-loop control system that actively suppresses circulating current while maintaining the parallel configuration for high power conversion capability
Solution Approach 2:
The patent changes the parameter of the drive signal by superimposing a compensation amount (generated from detected circulating current) onto the original drive signal. This parameter modification allows the system to eliminate circulating current effects while preserving the beneficial parallel connection for enhanced power conversion capability
2Productivity
If multiple non-isolated AC-DC conversion apparatuses are connected in parallel to increase charging rate, then the charging rate is improved, but power conversion efficiency decreases due to circulating current losses
Solution Approach 1:
The circulating current detection and compensation system continuously monitors and adjusts the drive signal based on detected circulating current, creating a feedback loop that minimizes energy losses while maintaining the high charging rate enabled by parallel apparatus configuration
Solution Approach 2:
The patent converts the harmful circulating current into a useful control signal by detecting it and using it to generate a compensation amount that adjusts the drive signal, thereby transforming the energy loss into a mechanism for improving overall system efficiency
3Object-generated harmful factors
If circulating current suppression is implemented through traditional methods, then circulating current is reduced, but additional hardware devices need to be added
Solution Approach 1:
The circulating current controller is integrated into the existing control architecture of the AC-DC conversion apparatus, serving multiple functions: normal power conversion control and circulating current suppression. This multi-functionality eliminates the need for separate dedicated hardware devices while achieving effective circulating current reduction
Solution Approach 2:
The patent merges the circulating current suppression function with the existing control system by integrating the circulating current controller into the apparatus. This consolidation combines multiple control functions into a unified system, reducing hardware complexity while maintaining effective circulating current suppression
Data Source
AI summary
A power conversion apparatus includes an AC-DC conversion circuit, a power controller, and a circulating current controller. The power controller is configured to control the AC-DC conversion circuit to convert a received alternating current into a first direct current and output the first direct current. The circulating current controller is configured to send a synchronization signal to another power conversion apparatus through a controller area network (CAN) bus. The synchronization signal is used to synchronize a carrier of the another power conversion apparatus with a carrier of the power conversion apparatus.