Adaptive PWM Wave Selection for Light-Load Power Loss
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Solution Overview
Problem
Conventional multilevel pulse width modulation (PWM) signals suffer from inefficiencies due to constant amplitude, duty cycle, and switching frequency, leading to increased power consumption and conduction losses under varying load conditions, as they fail to adaptively adjust amplitude and frequency.
Innovation Solution
A PWM method that generates output signals by comparing input signals with triangular or sawtooth waves of varying amplitudes and frequencies, adjusting duty cycles and switching frequencies based on load conditions to minimize power consumption and ripple current, using a common mode non-zero offset to reduce RMS power during light loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the multilevel PWM signal uses constant amplitude in different level ranges, then the signal structure is simple, but the ripple current increases under light load condition, resulting in larger conduction loss
Solution Approach 1:
The patent applies dynamics by making the PWM signal amplitude variable rather than constant. The signal amplitude is dynamically adjusted based on the instantaneous input signal level, transitioning from a fixed structure to an adaptive one that responds to load conditions, thereby reducing ripple current and conduction loss under light load while maintaining simplicity through systematic control
2Ease of operation
If the multilevel PWM signal uses 50% duty cycle during idle condition, then the control is simple, but the idle condition current increases, causing larger power consumption
Solution Approach 1:
The patent applies parameter changes by modifying the duty cycle parameter from a fixed 50% value to a variable parameter that adapts to idle and light load conditions. By changing the duty cycle parameter dynamically, the system reduces idle condition current and power consumption while maintaining control simplicity through automated parameter adjustment based on signal level detection
3Ease of operation
If the multilevel PWM signal uses constant switching frequency, then the frequency control is simple, but the ripple current increases under light load condition, resulting in larger power consumption
Solution Approach 1:
The patent applies dynamics by transforming the switching frequency from a constant parameter to a dynamic parameter that adjusts according to load conditions. The frequency is modulated in response to input signal level, enabling automatic optimization of ripple current and power consumption without complex manual frequency control mechanisms
4Device complexity
If the multilevel PWM signal cannot increase amplitude adaptively under heavy load condition, then the signal structure remains simple, but the on-current is high, resulting in high conduction loss
Solution Approach 1:
The patent applies parameter changes by making the signal amplitude a variable parameter that adapts to heavy load conditions. The amplitude parameter is dynamically increased when needed to reduce on-current and conduction loss, achieving energy optimization while maintaining signal structure simplicity through systematic parameter modulation rather than structural complexity
Data Source
AI summary
A pulse width modulation (PWM) method for converting an input signal into an output PWM signal includes the following steps: generating a first linear periodic wave and a second linear periodic wave which are triangle waves or sawtooth waves, wherein the amplitude of the first linear periodic wave is greater than the amplitude of the second linear periodic wave; determining whether the level of the input signal is lower than a light load threshold; when the level of the input signal is lower than the light load threshold, generating the output PWM signal according to a comparison between the input signal and the second linear periodic wave; and when the level of the input signal is higher than the light load threshold, generating the output PWM signal according to a comparison between the input signal and the first linear periodic wave.