Variable-Frequency PWM Compensation for Stable Power Output
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Solution Overview
Problem
Conventional variable-frequency energy-saving circuits face issues with non-synchronicity and low-frequency/beat-frequency noise, leading to unstable output voltage and integration challenges with other circuits, especially during load variations.
Innovation Solution
A variable-frequency circuit with a compensation mechanism that adjusts the PWM unit's working cycle signal using a load sensing/decision unit, frequency-division unit, and level modulation unit, which generates a reference frequency and level signal to stabilize output voltage during frequency variations, synchronizing with load changes and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If variable-frequency energy-saving circuit is used to reduce switching loss, then energy efficiency is improved, but output voltage stability deteriorates due to voltage fluctuation during frequency variation
Solution Approach 1:
The patent applies preliminary anti-action by detecting voltage fluctuation trends before they become problematic. The circuit monitors voltage changes during frequency variation and preemptively adjusts the frequency variation rate or adds compensation signals to counteract expected voltage deviations, thereby maintaining output voltage stability while preserving the energy-saving benefits of variable-frequency operation
Solution Approach 2:
The patent implements feedback mechanisms that continuously monitor output voltage and adjust frequency variation accordingly. When voltage fluctuation exceeds a threshold, the system reduces the frequency variation rate or introduces compensation signals to bring voltage back to the desired level, creating a closed-loop control system that balances energy efficiency with voltage stability
2Loss of energy
If frequency is adjusted to vary with load for energy saving, then switching loss is reduced, but synchronicity with power-factor regulation circuit and PWM circuit deteriorates, generating beat-frequency noise
Solution Approach 1:
The patent introduces an intermediary frequency adjustment mechanism that acts as a buffer between the load variation and the PWM circuit. This intermediary layer smoothly transitions frequency changes, preventing direct coupling between load variations and the PWM circuit, thereby eliminating beat-frequency noise while maintaining the energy-saving frequency adaptation benefit
Solution Approach 2:
The patent applies dynamics by making the frequency adjustment rate adaptive rather than fixed. The system dynamically adjusts how quickly frequency changes in response to load variations, using slower transition rates during certain operating conditions to maintain synchronicity with other circuits and avoid generating audible or interfering frequencies
3Loss of energy
If frequency variation is implemented for energy saving, then switching loss is reduced, but integration with power-factor regulation circuit and PWM circuit becomes difficult
Solution Approach 1:
The patent merges the frequency adjustment function with existing circuit components rather than adding a separate independent system. The frequency variation mechanism is integrated into the PWM control circuitry and power-factor regulation circuit, allowing all three functions (power-factor correction, PWM control, and frequency adaptation) to share common hardware resources and control logic, thereby reducing overall circuit complexity
Data Source
AI summary
The present invention discloses a variable-frequency circuit with a compensation mechanism, which comprises: a load sensing/decision unit, a frequency-division unit and a level modulation unit. The present invention applies to a power supply having a frequency-division mode. The power supply has a feedback unit generating a feedback signal. The load sensing/decision unit determines the operational mode according to the feedback signal. The frequency-division unit generates a reference frequency signal. The level modulation unit generates a reference level signal. During frequency variation, the level modulation unit generates a compensation current to modulate the reference level signal. Thereby, the PWM unit of the power supply can adjust the working cycle of the power supply according to the reference frequency signal, the reference level signal and the feedback signal.