PWM Carrier Frequency Adjustment via Control Deviation Integration
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Solution Overview
Problem
Existing power convertors face challenges in enhancing control responsiveness and accurately adjusting carrier frequency due to noise and detection errors, particularly in PWM control systems.
Innovation Solution
A power convertor system that includes a PWM controller and a frequency changer, utilizing an outputter, integrator, and frequency determiner to dynamically adjust the carrier frequency based on control deviations, integrating control values to determine optimal carrier frequencies and adjust for errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If carrier frequency is adjusted dynamically to enhance control responsiveness, then control responsiveness is improved, but measurement precision deteriorates due to noise and detection errors
Solution Approach 1:
The system performs preliminary actions by integrating the control deviation over time before making carrier frequency adjustments. The integrator accumulates error signals over multiple PWM cycles, allowing the system to build up a reliable frequency adjustment command before actually changing the carrier frequency, thus preventing premature or erroneous adjustments
Solution Approach 2:
The system implements feedback by continuously monitoring the control deviation and using it to adjust the carrier frequency through the integrator and frequency determiner. The frequency determiner compares the integrated value against threshold values and adjusts the carrier frequency accordingly, creating a closed-loop feedback mechanism that improves measurement precision while maintaining responsiveness
2Speed
If carrier frequency is changed frequently to improve control responsiveness, then control responsiveness is improved, but reliability deteriorates due to noise influence
Solution Approach 1:
The integrator performs preliminary accumulation of control deviation signals before triggering any carrier frequency change. This preliminary action ensures that frequency adjustments are based on sustained error conditions rather than transient noise spikes, thereby improving reliability while maintaining the ability to respond to genuine control deviations
Solution Approach 2:
The system provides beforehand cushioning by using the integrator to smooth out noise and transient errors before they can trigger inappropriate carrier frequency changes. The integration process acts as a cushion that absorbs the impact of noise, preventing unreliable frequency adjustments while still allowing responsive changes when genuine control deviations occur
Data Source
AI summary
A power convertor includes a power conversion unit, a PWM controller, and a frequency changer. The power conversion unit includes a plurality of switching elements. The PWM controller is configured to perform PWM control of the plurality of switching elements. The frequency changer is configured to change a carrier frequency in the PWM control. The frequency changer includes an outputter, an integrator, and a frequency determiner. The outputter is configured to output a control value in accordance with a control deviation with respect to a control target. The integrator is configured to integrate the control value output from the outputter. The frequency determiner is configured to determine the carrier frequency based on an integral value obtained by the integrator.