Parallel Bidirectional Converter Current Sharing on a Single Bus
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Solution Overview
Problem
Bidirectional DC-DC converter systems connected in parallel require two current-sharing signals due to bidirectional operation, necessitating two current-sharing buses and increased complexity and cost, especially in isolated converters.
Innovation Solution
A single common current-sharing signal is used across bidirectional DC-DC converters connected in parallel, with first and second bidirectional current-sense circuits at input/output and output/input nodes respectively, utilizing resistors or Hall-effect sensors, and a controller to calculate PWM, PFM, or phase shift modulation signals for current sharing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two current-sharing signals are used for bidirectional converters, then current sharing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the two separate current-sharing signals (one for each power direction) into a single shared current-sharing signal. The controller selectively applies this single signal to control both the first and second bidirectional converters regardless of power flow direction, thereby reducing the number of current-sharing buses from two to one while maintaining accurate current sharing through intelligent selective control.
2Measurement precision
If two current-sharing buses are used, then current sharing control is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines two separate current-sharing buses into a single current-sharing bus that carries one shared current-sharing signal. This reduction in hardware components directly lowers manufacturing costs while the controller's selective control logic ensures that current sharing accuracy is maintained for both power flow directions.
3Reliability
If isolation is provided between current sharing buses, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for isolation circuitry between current-sharing buses by using a single shared current-sharing signal. Since there is only one bus, the complexity of providing isolation between multiple buses is removed, while reliability is maintained through the controller's ability to selectively control power flow direction and adjust converter operation accordingly.
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 simplifies the system, reduces manufacturing costs, and maintains effective current sharing among converters, ensuring redundancy and continuous operation even if one converter fails, while eliminating the need for separate current-sharing buses.
Implementation Method 1
Each of the first bidirectional converter and the second bidirectional converter may include a first current-sense circuit connected to the first node and a second current-sense circuit connected to the second node. At least one of the first and second current-sense circuits may include a resistor or a Hall-effect sensor.
Data Source
AI summary
A converter system includes a first bidirectional converter electrically connected between a first node and a second node and a second bidirectional converter electrically connected between the first node and the second node in parallel with the first bidirectional converter. Current is shared between the first bidirectional converter and the second bidirectional converter based on a single current-sharing signal.