Transformer Magnetization Bias Control via Current Difference
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Solution Overview
Problem
Existing power conversion systems with transformers face challenges in accurately predicting and correcting magnetization bias due to offset errors in current detection, leading to reduced prediction accuracy and ineffective bias reduction.
Innovation Solution
A control apparatus that includes a current sensor to detect currents during specific switch ON periods, allowing for the prediction of magnetization bias by calculating the difference between these currents, thereby isolating and canceling offset errors, and adjusting the drive mode of the inverter or rectifier circuit to reduce magnetization bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current detection device is used to predict magnetization bias, then magnetization bias prediction capability is provided, but offset errors reduce prediction accuracy
Solution Approach 1:
The patent extracts and removes the offset error component from the current detection signal by calculating the difference between currents measured during opposite switching states. This isolation technique separates the useful magnetization bias information from the harmful offset error, enabling accurate prediction without the contamination of detection device errors
Solution Approach 2:
The system implements feedback by using the predicted magnetization bias amount to dynamically adjust the drive modes of the inverter or rectifier circuits. The control unit continuously monitors the magnetization bias level and modifies switching patterns accordingly, creating a closed-loop control system that actively compensates for magnetization bias in real-time
2Device complexity
If magnetization bias prediction accuracy is lowered, then system complexity is reduced, but magnetization bias correction becomes ineffective
Solution Approach 1:
The patent introduces an intermediary calculation method that uses the difference between primary and secondary current measurements as a mediator to determine magnetization bias. This intermediary approach avoids the need for complex direct excitation current measurement while maintaining prediction accuracy, as the difference calculation naturally eliminates offset errors and provides reliable magnetization bias information
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 enables accurate prediction and reduction of magnetization bias in transformers, improving the accuracy of magnetization bias correction and maintaining the balance of the voltage-time product across the transformer, thus effectively addressing the limitations of existing systems.
Implementation Method 1
a transformer; an inverter circuit that controls a first input switch and a second input switch to be ON and OFF to convert a direct current (DC) into an alternating current (AC), thereby allowing the alternating current to flow through a primary coil of the transformer; a rectifier circuit that converts an AC voltage of a secondary coil of the transformer into a DC voltage
Data Source
AI summary
A control unit capable of accurately calculating a magnetization bias of a transformer is provided, thereby appropriately reducing the magnetization bias. The control unit acquires first and second currents that flow through a transformer during a period where either first or second switches individually turn ON. The control unit predicts an amount of magnetization bias in either positive side or negative side of the excitation current that flows through the transformer. The control unit reduces the magnetization bias of the transformer based on the predicted amount of magnetization bias.