Bidirectional DC/DC Converter Phase and Frequency Control
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Solution Overview
Problem
Bidirectional DC/DC converters, such as DAB converters, face inefficiencies in power transmission when the voltage difference between the primary and secondary sides is significant, leading to excessive power transmission and potential losses due to intermittent operation below a threshold value.
Innovation Solution
A power conversion device with a control method that adjusts the phase difference, frequency, and pause period of switching operations in the primary and secondary circuits to optimize power transmission, using a control device that selects appropriate command values and adjusts switching parameters to prevent excessive power transmission and maintain efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If intermittent operation is performed when power transmission is below threshold, then power losses are reduced, but transmission efficiency deteriorates due to excessive power transmission
Solution Approach 1:
The patent applies dynamics by making the switching frequency adjustable rather than fixed. The control device dynamically changes the switching frequency based on the detected power transmission amount, increasing frequency when power is low and decreasing it when power is high, thereby optimizing both efficiency and loss reduction under varying conditions
Solution Approach 2:
The patent changes the parameter of switching frequency to resolve the contradiction. By varying the switching frequency as a control parameter in response to power transmission levels, the system achieves optimal balance between reducing power losses and maintaining transmission efficiency across different operating conditions
2Measurement precision
If switching frequency is increased to improve power transmission control, then transmission precision is improved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts switching frequency based on real-time power transmission detection, using higher frequencies only when necessary for precise control at low power levels, and reducing frequency at higher power levels to minimize energy consumption while maintaining adequate control precision
3Productivity
If phase difference and pause period are adjusted to regulate power transmission, then power transmission efficiency is improved, but device complexity increases
Solution Approach 1:
The control device performs multiple functions using a single integrated controller: detecting power transmission amount, calculating appropriate switching parameters, generating control signals, and adjusting phase difference and pause period. This multi-functionality improves power transmission efficiency while avoiding the need for separate dedicated devices for each function
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
The solution effectively regulates power transmission by adjusting phase difference, frequency, and pause periods, ensuring efficient energy transfer and reducing losses, even when the voltage difference is substantial, thereby improving the overall efficiency of bidirectional power conversion.
Implementation Method 1
bridge circuits on a primary-side and a secondary-side are connected via a transformer
Data Source
AI summary
A power conversion device includes a transformer, and a first bridge circuit connected to a primary-side of the transformer and capable of switching a polarity of a connection between a pair of DC bus bars on the primary-side and the transformer. A second bridge circuit is connected to a secondary-side of the transformer and capable of switching a polarity of a connection between a pair of DC bus bars on the secondary-side and the transformer. A control device is provided which is capable of performing control of switching the first bridge circuit and the second bridge circuit with a phase difference. The control device has a frequency adjustment unit for adjusting a frequency of switching of the first bridge circuit and the second bridge circuit, according to an output from the first bridge circuit or the second bridge circuit and a target value.