Three-Phase PPP Inverter Using Stacked DAHB Soft-Switching Control
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Solution Overview
Problem
Existing partial power processing (PPP) converters face limitations in AC systems, particularly in maintaining efficiency and soft-switching capabilities when interfacing with AC grids, and are often restricted to two-stage inverters.
Innovation Solution
A three-phase PPP inverter framework using stacked dual-active-half-bridge (DAHB) circuits with dynamic switching frequency control maintains soft-switching over the grid cycle, improving efficiency and power density by processing less power internally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional full power processing (FPP) converters are used in AC systems, then complete power conversion is achieved, but efficiency is reduced due to processing all power internally
Solution Approach 1:
The power processing function is segmented into two paths: a processed power path through the DAHB converter and a direct power path bypassing the converter. This segmentation allows only the necessary portion of power to be processed internally, improving efficiency while maintaining complete power delivery to the AC grid.
Solution Approach 2:
Instead of processing all power through the converter, the system applies partial power processing where only a portion of the total power undergoes conversion. The voltage conversion ratio is leveraged to determine the optimal processed power portion, reducing converter losses while ensuring complete power delivery.
2Power
If switching frequency is increased to improve power density, then converter size is reduced, but soft-switching capability is lost leading to increased losses
Solution Approach 1:
The switching frequency is made dynamic rather than fixed, allowing the system to adapt the frequency based on operating conditions. The controller adjusts the switching frequency to maintain soft-switching operation across varying power levels and voltage conversion ratios, minimizing switching losses while maximizing power density.
Solution Approach 2:
The system changes the switching frequency parameter dynamically to maintain optimal operation. By adjusting this key parameter based on real-time conditions, the system preserves soft-switching capability across the full operating range, reducing energy losses while maintaining high power density.
3Loss of energy
If voltage conversion ratio is increased to improve power processing efficiency, then less power needs to be processed, but the operating range becomes more limited
Solution Approach 1:
The voltage conversion ratio is made dynamic, allowing the system to adjust the conversion ratio based on the specific operating conditions and grid requirements. This dynamic adjustment enables the system to optimize processing efficiency for each operating point while maintaining adaptability across a wide voltage conversion range.
Solution Approach 2:
The DAHB converter topology provides multi-functionality by operating effectively across a wide range of voltage conversion ratios. The converter can adapt its operation to serve different voltage levels and power requirements, maintaining efficiency while providing broad adaptability to various AC grid conditions.
4Device complexity
If hard-switching operation is used to simplify control, then control complexity is reduced, but efficiency deteriorates due to higher switching losses
Solution Approach 1:
The control system incorporates feedback mechanisms that monitor operating conditions and adjust switching signals accordingly. This feedback enables the system to maintain soft-switching operation by detecting when switching conditions are optimal and adjusting the timing to preserve zero-voltage or zero-current switching, reducing losses while managing control complexity.
Solution Approach 2:
The control system prepares the switching devices for soft-switching operation by pre-charging or pre-discharging switching nodes before the actual switching event. This preliminary action ensures that switches transition at optimal moments, enabling soft-switching without requiring complex real-time control adjustments during the switching event itself.
Data Source
AI summary
Disclosed are systems, method, devices, and other implementations, including a voltage inverter system that includes multiple modular phase circuits to invert DC voltage into a multiple phase AC output voltage provided to an electrical grid, with each of the modular phase circuits including a reconfigured stacked dual-active-half-bridge (DAHB) circuit folded across a galvanic isolation between a primary side and a secondary side of the DAHB to stack the primary side in series with the secondary side, and one or more controllers to control electrical operation of the multiple modular phase circuits. In some embodiments, the reconfigured stacked DAHB circuits of the multiple modular phase circuits may be configured to perform partial power processing. In some examples, the controllers can be configured to maintain soft-switching operations for switching devices coupled to capacitors of the stacked DAHB circuits, or maintain substantially constant switching frequencies for the stacked DAHB circuits.