Bridge Switching Circuit Narrow Pulse Suppression in PWM Control
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Solution Overview
Problem
Bridge switching circuits in power electronics face challenges in suppressing narrow pulses, which can lead to surge voltage spikes and damage to switching devices, despite the introduction of turn-on-dead-time, as narrow turn-on pulses can still occur, threatening device reliability and increasing electromagnetic interference.
Innovation Solution
A method and device that detect whether the comparison value of a modulated wave is within a preset narrow pulse interval in a bridge switching circuit, adjusting the comparison value to prevent narrow pulses by determining the relevant adjustment interval and modifying the modulated wave accordingly, ensuring that the sum with adjacent cycle values does not fall within the narrow pulse interval, thus avoiding pulse width modulation limitations and maintaining maximum output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If turn-on-dead-time is introduced to prevent upper and lower switch transistors from being turned on at the same time, then device safety is improved, but narrow turn-on pulses may still be produced causing electromagnetic interference
Solution Approach 1:
The patent applies preliminary action by detecting and adjusting the comparison value before the PWM pulse is generated. The control device checks whether the comparison value falls within a narrow pulse interval and adjusts it in advance to prevent narrow pulse generation, thereby eliminating electromagnetic interference before it occurs while maintaining device safety through proper dead-time implementation
2Object-generated harmful factors
If narrow pulse suppression is implemented by adjusting comparison values, then electromagnetic interference is reduced, but modulation degree may be reduced
Solution Approach 1:
The patent uses parameter changes by dynamically adjusting the comparison value parameter based on its detected range. When the comparison value falls within the narrow pulse interval, it is transformed to a boundary value outside this interval. This parameter transformation suppresses narrow pulses and electromagnetic interference while preserving the modulation degree by maintaining the adjusted comparison value for PWM generation
Data Source
AI summary
A method for suppressing a narrow pulse is provided. The method is applied to a bridge switch circuit having at least one bridge arm which has an upper switch transistor and a lower switch transistor, and includes: detecting whether an original comparison value of a modulated wave in a current cycle is in a preset narrow pulse interval of the upper switch transistor, and if so, determining an adjustment interval of the upper switch transistor to which the original comparison value of the modulated wave currently pertains; and adjusting the original comparison value of the modulated wave to an adjusted comparison value of the modulated wave corresponding to the adjustment interval of the upper switch transistor to which the original comparison value of the modulated wave currently pertains according to a corresponding relationship between adjustment intervals of the upper switch transistor and adjusted comparison values of the modulated wave.