Multi-Thread Power Converter Dynamic Switching Patterns
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Solution Overview
Problem
Wind turbine power converters face efficiency losses due to thermal limitations of semiconductor switches and adverse impacts from filtering harmonic content, which reduces the quality of power output.
Innovation Solution
A multi-thread power converter system with increased common mode inductance and dynamic switching patterns between half-interleaved and fully-interleaved patterns, along with adjustable switching frequencies, is employed to reduce common mode current and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If semiconductor switches are operated at high frequencies to improve power output quality, then switching speed is improved, but thermal limitations prevent the switches from operating at high frequencies
Solution Approach 1:
The patent implements dynamic switching patterns where the converter threads switch between different operating states (active, bypass, disabled) based on real-time conditions. This dynamic operation allows the system to optimize switching frequency and duty cycle, enabling high-frequency operation when thermal conditions permit while reducing frequency when thermal limits are approached, thus resolving the contradiction between switching speed and thermal constraints
Solution Approach 2:
The patent employs periodic switching patterns where converter threads are activated in alternating phases rather than continuously. By implementing periodic activation with configurable duty cycles and using bypass switches to alternate current paths, the system can operate at high frequencies during active phases while allowing thermal dissipation during inactive phases, thereby achieving high switching frequencies without exceeding thermal limitations
2Reliability
If filters and chokes are coupled to filter harmonic content from electricity, then power output quality is improved, but efficiency of the power converter is adversely impacted
Solution Approach 1:
The patent extracts the harmonic filtering function from traditional passive filters and chokes by implementing active filtering through the multi-thread converter architecture. Each converter thread with its PWM-controlled switches actively synthesizes and injects counter-harmonic currents, eliminating the need for bulky passive filtering components that cause energy losses, thus improving efficiency while maintaining power output quality
Solution Approach 2:
The patent replaces mechanical/passive filtering components (filters and chokes) with an electronic control system using PWM-switched converter threads. This substitution uses electronic switching and control algorithms to achieve harmonic cancellation, replacing the passive electromagnetic filtering mechanism with an active electronic control mechanism that has lower energy losses while maintaining or improving power quality
3Power
If converter threads are operated in parallel to increase power output, then power capacity is improved, but common mode current increases causing efficiency losses
Solution Approach 1:
The patent implements local quality control by independently managing each converter thread's switching pattern and duty cycle. By allowing each thread to operate with optimized local parameters (different phase shifts, duty cycles, and activation patterns), the system achieves balanced current distribution that minimizes common mode currents while maintaining total power output, thus resolving the contradiction between power capacity and efficiency
Solution Approach 2:
The patent employs dynamic control of converter threads where the number of active threads, their switching frequencies, and phase relationships are continuously adjusted based on load conditions. This dynamic optimization ensures that threads operate in a coordinated manner that cancels common mode currents while delivering required power, preventing efficiency losses even as power capacity scales with additional parallel threads
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 significantly reduces power converter losses by minimizing common mode current and maintaining efficiency even at higher switching frequencies, thereby improving the overall efficiency of the wind turbine power conversion process.
Implementation Method 1
a filter including a common mode inductor configured to reduce a common mode current in the power converter system
Implementation Method 2
Some known power converters include semiconductor switches capable of handling high currents and voltages. Typically, rapid switching of the semiconductor switches is beneficial to the quality of the power output of the converter.
Data Source
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AI summary
A power generation system (200) for providing an output power to a load is provided. The power generation system (200) includes a generator (120) configured to generate an alternating current (AC) input power, a power converter system (202) coupled to the generator, the power converter system including a plurality of converter threads (224,226,228,230) configured to convert the AC input power to an output power and to provide the output power to the load, and a converter control system (204) coupled to the power converter system, the converter control system configured to provide the power converter system with one of a first switching pattern and a second switching pattern based at least partially on a monitored operating characteristic of the generator.