Power Converter Offset Voltage for Switching Device Heat Balancing
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Solution Overview
Problem
Existing power converter technologies fail to accurately distribute heat generation among switching devices in poly-phase systems, especially when the maximum heating phases for the positive and negative electrode sides differ, leading to increased heat generation and calculation complexity.
Innovation Solution
The power converter adjusts the offset voltage to balance the heating evaluation values of the positive and negative electrode side switching devices, minimizing the maximum heating evaluation value and ensuring accurate heat distribution across all phases, even when the maximum heating phases change before and after applying the offset voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heating amount before applying offset voltage is calculated and used to select maximum heating phases, then heat distribution is possible even when maximum heating phases differ, but the maximum heating phase selection becomes inaccurate when maximum heating phases change before and after applying offset voltage
Solution Approach 1:
The patent applies offset voltage to the AC voltage commands before calculating the heating amounts. This preliminary action ensures that the maximum heating phases are identified based on the actual operating conditions after offset voltage application, rather than before. By performing the heating amount calculation after offset voltage is applied, the system accurately identifies which phases will actually experience maximum heating, leading to more reliable heat distribution control.
2Reliability
If heating amounts of all switching devices are calculated to select maximum heating phases, then accurate heat distribution is achieved, but calculation load becomes large
Solution Approach 1:
The patent extracts and uses only the necessary information for heat distribution control - specifically, the AC voltage command values and their phases. Instead of calculating heating amounts for all switching devices comprehensively, the method focuses on identifying the maximum heating phases by analyzing the AC voltage commands directly. This extraction of essential information reduces the calculation burden while maintaining the accuracy needed for effective heat distribution.
3Reliability
If offset voltage is applied to distribute heat generation, then heat distribution is improved, but the maximum heating amount may increase when maximum heating phases are incorrectly selected
Solution Approach 1:
The patent implements a feedback mechanism where the heating amounts are calculated after offset voltage is applied, and this calculated information is used to verify and adjust the identification of maximum heating phases. By continuously monitoring the actual heating conditions after offset voltage application and using this feedback to confirm phase selection, the system ensures that offset voltage is applied correctly without causing unintended increases in maximum heating amounts due to incorrect phase identification.
Data Source
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AI summary
To provide a power converter which can distribute heat generation of the switching devices with good accuracy, even when the maximum heating phase of the positive electrode side and the maximum heating phase of the negative electrode side are different phases, and even when the maximum heating phase of the positive electrode side and the maximum heating phase of the negative electrode side changes before and after combining the offset voltage. The power converter (1) calculates the offset voltage (Voff) that makes the positive electrode side maximum heating evaluation value (Qmaxp) and the negative electrode side maximum heating evaluation value (Qmaxn) coincide with each other, in a state of controlling on/off the switching devices based on the combined AC voltage commands of the offset voltage (Voff).