Spread Spectrum PWM Converter With Random Pulse Omission
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Solution Overview
Problem
Conventional switching converters experience noise interference, electromagnetic interference (EMI), and electromagnetic radiation (EMR) due to periodic major frequencies in the frequency spectrum of the output power during light load operation states.
Innovation Solution
A spread spectrum switching converter that randomly adjusts the error amplification signal, omission reference signal, or delay time of the omission control signal to broaden the frequency spectrum of the modulation signal and output power, thereby suppressing unwanted periodic major frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pulse omission control is used in light load operation state, then power utilization efficiency is improved, but noise interference and electromagnetic interference are increased due to periodic major frequencies
Solution Approach 1:
The patent applies dynamics by making the omission control signal dynamic rather than periodic. A random number generator creates variable omission patterns where the number of omitted pulses varies randomly, transforming the static periodic omission into a dynamic aperiodic omission that maintains efficiency while eliminating EMI
Solution Approach 2:
The patent changes the parameter of omission pattern from periodic to random. By using a random number generator to determine the number of omitted pulses in each cycle, the fundamental frequency and its harmonics are eliminated, converting the harmful periodic EMI into broadband random noise that does not interfere with load operation
2Productivity
If periodic pulse omission is applied to improve power efficiency, then power utilization is enhanced, but obvious periodic major frequencies cause electromagnetic radiation
Solution Approach 1:
The invention transforms the static periodic omission pattern into a dynamic random omission pattern. The random number generator continuously varies the omission characteristics, preventing the formation of consistent electromagnetic radiation patterns while maintaining the power efficiency benefits of pulse omission
Solution Approach 2:
The patent converts the harmful periodic EMI into beneficial random noise. By randomizing the omission pattern, the concentrated electromagnetic energy at specific frequencies is dispersed into broadband random noise, which is less harmful and does not cause resonance or interference issues
Data Source
AI summary
A spread spectrum switching converter converts an input power to an output power. The spread spectrum switching converter includes a pulse width modulation (PWM) circuit and a pulse omission control circuit. The PWM circuit generate an initial PWM signal according to a feedback signal related to the output power. The initial PWM signal controls at least one switch to switch an inductor to generate the output power. The pulse omission control circuit generates a pulse omission control signal to mask a portion of pulses of the initial PWM signal, to thereby generate an adjusted PWM signal. The pulse omission control circuit randomly adjusts the pulse width of the pulse omission control signal according to a random control signal, such that the adjusted PWM signal has a spread spectrum characteristic.