Parallel Power Conversion Device Current Balancing
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Solution Overview
Problem
Power conversion devices with multiple switching power supply devices in parallel face current imbalances due to element variations and wiring differences, leading to increased costs and sizes as drive circuits for low voltage side elements are duplicated, hindering efficiency and design optimizations.
Innovation Solution
A power conversion device configuration using transformers to connect low and high voltage side circuits, with controlled switching timings to balance input currents between parallel circuits, reducing the need for independent drive circuits for low voltage side elements and minimizing current imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple switching power supply devices are connected in parallel to reduce copper loss and improve conversion efficiency, then conversion efficiency is improved, but current imbalance occurs between the switching power supplies due to element variation or wiring line length differences
Solution Approach 1:
The control circuit detects the output current of each switching power supply device and feeds back this information to adjust the duty ratio of each device. This closed-loop feedback mechanism dynamically compensates for current imbalance caused by element variations or wiring differences, ensuring stable current distribution across parallel devices without requiring excessive design margins.
Solution Approach 2:
The control circuit independently adjusts the duty ratio parameter for each switching power supply device based on its actual output current. By changing this operational parameter dynamically, the system optimizes current distribution across parallel devices, allowing them to operate at optimal points and reducing overall copper loss while maintaining balance.
2Reliability
If independent control of switching elements in each parallel switching power supply device is implemented to suppress current imbalance, then current imbalance is reduced, but drive circuits increase according to parallel number, increasing cost and size
Solution Approach 1:
The control circuits of multiple switching power supply devices are merged into a single integrated control circuit. This unified controller manages all parallel devices through a centralized architecture, reducing the total number of independent drive circuits while maintaining independent control capability for each device through shared control resources and communication mechanisms.
Solution Approach 2:
The integrated control circuit is designed with multi-functionality to handle control tasks for multiple parallel switching power supply devices simultaneously. It can dynamically allocate its control capacity across different devices based on operational requirements, providing universal control functionality that reduces overall system complexity while maintaining effective current imbalance suppression.
3Reliability
If design value with margin is required for switching power supplies connected in parallel to account for current imbalance, then reliability is improved, but sizes and costs of the switching power supplies increase
Solution Approach 1:
Real-time current detection and feedback control enable the system to dynamically compensate for imbalances, eliminating the need for conservative design margins. The feedback mechanism ensures that each device operates within safe limits by continuously monitoring and adjusting its output, allowing for more compact and cost-effective designs without sacrificing reliability.
Solution Approach 2:
The system transitions from static design margins to dynamic current balancing through real-time control. Instead of designing for worst-case scenarios with fixed margins, the system actively adapts to actual operating conditions, allowing components to be sized more efficiently while maintaining reliability through dynamic adjustment rather than static overdesign.
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 configuration effectively suppresses current imbalances in parallel power supply devices, reducing the overall cost and size of the power conversion device while improving efficiency and reliability by balancing current flows and heat generation.
Implementation Method 1
a first low voltage side circuit (5) and a first high voltage side circuit (7) which are connected via a first transformer (11); and a second low voltage side circuit (6) and a second high voltage side circuit (8) which are connected via a second transformer (12)
Data Source
AI summary
A power conversion device includes: a first low voltage side circuit and a first high voltage side circuit which are connected via a first transformer; and a second low voltage side circuit and a second high voltage side circuit which are connected via a second transformer, wherein switching timings of the first high voltage side circuit and the second high voltage side circuit are controlled such that a current difference of an input current to the first low voltage side circuit and an input current to the second low voltage side circuit during a step-up operation becomes smaller than a predetermined value. A driver circuit to output a drive signal of a switching element may be included in at least one of the first low voltage side circuit and the second low voltage side circuit.