DC/DC Converter System for AC Voltage Generation with Soft Switching
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Solution Overview
Problem
Current inverter technologies face challenges in achieving a compromise between efficiency, harmonic generation, electromagnetic compatibility, and costs, particularly in generating AC voltage with fixed reference potentials and varying output voltages without galvanic isolation.
Innovation Solution
A DC/DC converter system that acts as both a step-up and step-down converter, generating AC voltage between output terminals with a fixed reference potential, allowing for positive and negative output voltages and reducing switching losses through soft switching of power switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional inverter topologies (full-bridge, HERIC, H5, NPC1) are used with hard switching of power semiconductors, then good efficiency can be achieved at certain operating points, but efficiency deteriorates across the entire operating range
Solution Approach 1:
The patent implements dynamic switching frequency adjustment where the switching frequency of power semiconductors is varied based on operating conditions. The controller adapts the switching frequency to optimize efficiency across different operating points, transitioning from fixed frequency hard switching to dynamic frequency control that reduces switching losses while maintaining performance across the full operating range.
Solution Approach 2:
The invention changes the switching frequency parameter dynamically based on operating conditions. By adjusting the switching frequency as a variable parameter rather than keeping it fixed, the system can optimize the trade-off between switching losses and conduction losses at different operating points, thereby improving overall efficiency across the entire operating range.
2Power
If low-side switches operate at fundamental frequency and high-side switches operate at higher switching frequency, then AC voltage generation is achieved, but harmonic generation increases
Solution Approach 1:
The patent incorporates feedback control mechanisms where the controller monitors the output voltage and current, and adjusts the switching patterns of power semiconductors to minimize harmonic content. The feedback loop detects harmonic distortions and modifies the switching frequency and duty cycle accordingly, reducing harmonic generation while maintaining effective AC voltage generation.
Solution Approach 2:
The invention employs periodic switching patterns with varying frequencies for different switch groups. By using periodic action with optimized frequency ratios and duty cycles, the system generates the required AC voltage while the periodic nature allows for controlled harmonic cancellation through proper timing and sequencing of switch operations.
3Power
If NPC1 topology with inner switches at fundamental frequency and outer switches at higher frequency is used, then voltage generation is achieved, but device complexity increases
Solution Approach 1:
The patent segments the switching circuit into distinct functional groups (inner switches and outer switches) with different switching frequency assignments. This segmentation allows each group to operate at optimized frequencies for their specific functions, achieving voltage generation while managing complexity through modular organization of the switching elements and their control.
4Adaptability or versatility
If step-up and step-down functions are implemented in DC/DC converters without galvanic isolation, then voltage flexibility is improved, but electromagnetic compatibility challenges arise
Solution Approach 1:
The patent introduces an intermediary control system that manages the DC/DC conversion process without galvanic isolation. The controller acts as an intermediary that coordinates the switching of power semiconductors to achieve both step-up and step-down voltage conversion while implementing electromagnetic interference mitigation strategies through controlled switching patterns and frequency management.
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 enhances efficiency, reduces harmonic generation, and improves electromagnetic compatibility while maintaining a constant output ground, thus addressing the limitations of existing inverter technologies.
Implementation Method 1
DC/DC converter with step-up and step-down functions
Data Source
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AI summary
The invention relates to a device for generating an AC voltage, consisting of a DC-DC voltage converter and a coupling of an input voltage supply to a first output voltage connection. The device for generating an AC voltage is designed to generate an AC voltage out of a DC voltage. A circuit arrangement for generating an output AC voltage, consisting of a DC-DC voltage converter and an energy sink which is coupled between an output voltage node and an input voltage supply. The circuit arrangement for generating an output AC voltage is designed to supply the energy sink with an AC voltage. A method realizes the mode for generating an output AC voltage. An exemplary embodiment relates to an inverter for generating an AC voltage. A further exemplary embodiment of the invention relates to an energy accumulator device for providing an AC voltage using a DC energy accumulator. Three further exemplary embodiments relate to three-phase inverters. Further exemplary embodiments relate to single-phase rectifier circuits and three-phase rectifier circuits.