Bidirectional Power Conversion Control for Heat Reduction
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Solution Overview
Problem
Existing power conversion systems, such as matrix converters, face challenges in managing frequency differences between the command frequency and the primary side frequency, leading to heat generation issues due to aligned secondary and primary side phases, which affects efficiency and reliability.
Innovation Solution
A power conversion apparatus that selects between two control modes based on the frequency difference: one mode where the secondary side frequency follows the command frequency, and another where the primary-secondary phase difference is maintained within a predetermined range, thereby avoiding phase alignment and reducing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the secondary side frequency is made to follow the command frequency, then the frequency control precision is improved, but when the primary and secondary sides are in phase, heat generation increases due to power loss
Solution Approach 1:
The control device continuously monitors the phase difference between primary and secondary sides and adjusts the secondary side frequency based on feedback. When the phase difference approaches zero, the system reduces the secondary side frequency to avoid in-phase alignment, thereby reducing power loss and heat generation while maintaining frequency control precision through active feedback adjustment
Solution Approach 2:
The system dynamically changes the operating parameters by adjusting the secondary side frequency based on the detected phase difference. When the primary and secondary sides are detected to be in phase, the secondary side frequency is reduced to create a deliberate frequency offset, transforming the system from a fixed frequency-following mode to a variable frequency mode that prevents harmful in-phase conditions
2Loss of energy
If the primary-secondary phase difference is maintained within a target range to avoid heat generation, then the energy loss is reduced, but the frequency control precision deteriorates
Solution Approach 1:
The control device implements dynamic frequency adjustment where the secondary side frequency is continuously adapted based on the real-time phase difference between primary and secondary sides. This dynamic approach allows the system to maintain an optimal phase difference for reducing heat generation while actively compensating to preserve frequency control precision through real-time parameter adjustment
Solution Approach 2:
The system changes the secondary side frequency parameter dynamically to maintain the primary-secondary phase difference within a target range. By adjusting this parameter based on phase difference measurements, the system achieves energy loss reduction while maintaining adequate frequency control precision through adaptive parameter optimization
3Device complexity
If a single control mode is used for all frequency conditions, then the device complexity is reduced, but the adaptability to different operating conditions deteriorates
Solution Approach 1:
The control device segments the control space into multiple frequency difference ranges, each with its own optimal control strategy. By dividing the frequency difference domain into distinct segments, the system can apply different control approaches for different operating conditions, improving adaptability while keeping each segment's control logic relatively simple
Solution Approach 2:
The control device dynamically switches between different control modes based on the detected frequency difference. This dynamic mode switching allows the system to adapt to various operating conditions automatically, achieving high versatility without requiring a permanently complex control structure, as only the necessary control mode is active at any given time
Data Source
AI summary
A power conversion apparatus includes: matrix converter circuitry configured to perform bidirectional power conversion between a primary side and a secondary side; and control circuitry configured to: select a first control mode in response to determining that a command-primary frequency difference between a command frequency and a primary side frequency of the matrix converter circuitry is above a predetermined threshold, wherein the first control mode includes causing a secondary side frequency of the matrix converter circuitry to follow the command frequency; select a second control mode in response to determining that the command-primary frequency difference is below the threshold, wherein the second control mode includes maintaining a primary-secondary phase difference between a secondary side phase and a primary side phase of the matrix converter circuitry within a predetermined target range; and control the matrix converter circuitry in accordance with a selection of the first control mode or the second control mode.