Wind Power Converter PWM Frequency Control Near Synchronous Speed
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Solution Overview
Problem
Existing wind power converters face challenges in reducing switching frequency without altering control parameters or system configuration, leading to high losses and reliability issues when operating near synchronous speed.
Innovation Solution
The method involves adjusting the amplitude of modulation voltage in consecutive switching cycles to generate PWM pulse signals with reduced frequencies, specifically by comparing the modulation voltage with a carrier wave to produce PWM pulse signals at 1/k of the original frequency, thereby reducing the switching frequency of wind power converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching frequency of the wind power converter is reduced to lower losses, then energy efficiency improves, but system reliability deteriorates due to complicated switching processes and configuration changes
Solution Approach 1:
The patent changes the parameter of modulation voltage amplitude dynamically based on rotor speed regions. When rotor speed is close to synchronous speed, the modulation voltage amplitude is reduced to 0.5 or less, which reduces the switching frequency and converter losses. This parameter change approach allows the system to adapt to different operating conditions without complicated configuration changes, thereby improving energy efficiency while maintaining reliability.
2Loss of energy
If control parameters are switched online to reduce switching frequency, then energy losses decrease, but device complexity increases due to modified peripheral configuration
Solution Approach 1:
The patent implements dynamic adjustment of modulation voltage amplitude based on real-time rotor speed detection. The control device continuously monitors rotor speed and dynamically changes the modulation voltage amplitude according to predetermined speed regions, enabling the system to adapt to varying operating conditions without requiring complex peripheral configuration modifications or manual parameter switching.
3Productivity
If the rotor operates near synchronous speed to increase generating capacity at low wind speed, then power generation efficiency improves, but converter losses increase due to high switching frequency
Solution Approach 1:
The patent implements periodic action by adjusting the modulation voltage amplitude in different rotor speed regions. When the rotor operates near synchronous speed (low wind speed condition), the modulation voltage amplitude is periodically reduced to 0.5 or less, which reduces the switching frequency and converter losses. This periodic adjustment strategy enables the system to maintain high generating capacity while minimizing energy losses during specific operating conditions.
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 effectively reduces the switching frequency of wind power converters without changing the control chip configuration, enhancing system reliability and reducing energy losses, while maintaining operational efficiency near synchronous speed.
Implementation Method 1
generating a pulse width modulation (PWM) pulse signal according to the adjusted modulation voltage
Data Source
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AI summary
The present disclosure provides a method of controlling a switching frequency of a wind power converter, a control device (213, 613) using the method, a wind power generation system (200, 600) using the method. The method includes: obtaining (S102) a three-phase modulation voltage of a generator-side converter (211); adjusting (S104) amplitude of the modulation voltage in k consecutive switching cycles; generating (S106) a PWM pulse signal according to the adjusted modulation voltage; and generating (S108) a control signal of the generator-side converter (211) according to the PWM pulse signal. A frequency of the generated PWM pulse signal is 1/k of a frequency of a first PWM pulse signal, k is an integer equal to or greater than 2, and the frequency of the first PWM pulse signal represents a frequency of a PWM pulse signal generated when the modulation voltage is not adjusted.