Dual Active Bridge Converter Control via Switching Mode Map
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Solution Overview
Problem
Conventional dual active bridge power converters face limitations in operating across a broad range of voltage ratios due to high switching and conduction losses, which can exceed the maximum current capability of semiconductor devices, leading to restricted operational ranges and control instabilities.
Innovation Solution
A controller generates a switching mode map that correlates different switching modes with contiguous and non-overlapping sets of system parameter value ranges, allowing for the selection of optimal gate trigger voltage timings to adjust the operation of primary and secondary bridges, thereby maintaining target voltage and power requirements across a wider range of voltage ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phase shift control is used to achieve bi-directional power flow over a broad voltage ratio range, then the operating range is enlarged, but large currents are driven inside converter components leading to higher conduction and switching losses
Solution Approach 1:
The patent divides the operating range into multiple discrete voltage ratio ranges, each associated with a specific switching mode. The controller segments the control strategy by selecting appropriate switching modes based on the current voltage ratio, thereby avoiding the need to operate in high-loss phase shift control modes across the entire range. This segmentation allows the system to maintain efficiency by using optimal control methods for each segment.
Solution Approach 2:
The patent implements dynamic switching mode selection based on real-time voltage ratio conditions. The controller dynamically transitions between different switching modes as the voltage ratio changes, optimizing the control strategy for each operating point. This dynamic adaptation prevents the system from being locked into a single control mode that would be inefficient across all conditions.
2Ease of operation
If phase shift control is used to simplify implementation and allow large operating range, then ease of operation is improved, but the current may exceed the maximum current capability of semiconductor devices
Solution Approach 1:
The patent segments the operating range into multiple voltage ratio ranges, each with predefined switching modes. This segmentation allows the controller to select appropriate modes that keep currents within safe limits for each specific operating condition, rather than using a single phase shift control mode that may exceed device capabilities in certain ranges.
Solution Approach 2:
The controller uses feedback from the measured voltage ratio to dynamically select the appropriate switching mode. This feedback mechanism ensures that the control strategy adapts to current operating conditions, preventing current excursions that would exceed semiconductor device capabilities while maintaining simple operation through automated mode selection.
3Reliability
If special operating modes are proposed to improve operation in special operating points, then reliability is improved, but switching between modes causes discontinuities and control instabilities
Solution Approach 1:
The patent pre-defines multiple switching modes and their transition boundaries before operation. By establishing the switching mode map in advance with clearly defined voltage ratio ranges for each mode, the system avoids abrupt or unpredictable mode transitions during operation. This preliminary preparation ensures smooth and stable transitions between operating modes.
Solution Approach 2:
The controller dynamically selects switching modes based on real-time voltage ratio measurements, with smooth transitions between modes as operating conditions change. The dynamic nature of the control allows the system to adapt continuously to changing conditions while maintaining stability through predefined transition criteria, avoiding the discontinuities associated with fixed mode switching.
Data Source
AI summary
A power converter includes primary and secondary bridges, a transformer, and a controller configured to generate a switching mode map that correlates each of a plurality of switching modes to a respective set of value ranges of system parameters of the power converter. The sets of system parameter value ranges are contiguous and non-overlapping across the switching mode map, each of the plurality of switching modes includes gate trigger voltage timings for commuting at least one of the primary and secondary bridges. The controller is configured to obtain a plurality of measured system parameter values, select from the switching mode map one of the plurality of switching modes that correlates to the set of system parameter values containing the plurality of measured system parameter values, and adjust gate trigger voltage timings of at least one of the primary and secondary bridges, according to the selected switching mode.