Switching Device Noise Diffusion via Variable Pulse Timing
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Solution Overview
Problem
Switching devices used in onboard power electronics systems generate noise that overlaps with radio frequencies, causing uncomfortable audio outputs and are difficult to suppress due to variations in component parts and narrow frequency bands, leading to ineffective noise reduction.
Innovation Solution
A switching device with a memory storing a basic pattern for generating drive pulses with varying leading and trailing time intervals, ensuring that switching frequencies and harmonics are diffused across a wide range of frequencies, avoiding overlap with audible bands and reducing noise energy levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a spectrum diffusion scheme is employed to diffuse energies of harmonic components, then the energy level of average noise is reduced, but switching frequencies and harmonics may still overlap with broadcast station frequencies causing audible noise
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The control device changes the switching frequency within a predetermined range based on detected broadcast station frequencies, allowing the system to adapt dynamically to avoid overlapping with audible frequency bands while maintaining noise diffusion benefits
Solution Approach 2:
The patent changes the switching frequency parameter within a predetermined range to avoid overlap with broadcast station frequencies. By adjusting this parameter dynamically based on detected frequencies, the system prevents audible noise while maintaining the noise diffusion effect
2Object-generated harmful factors
If a noise filter is provided on the switching device to reduce noise output, then noise suppression is achieved, but the filter becomes complex in structure and large in size
Solution Approach 1:
The patent extracts the noise filtering function from a separate physical filter component and implements it through software-based frequency detection and switching frequency adjustment. The control device detects broadcast frequencies and adjusts switching parameters to avoid overlap, eliminating the need for complex hardware filters
Solution Approach 2:
The patent replaces the mechanical/electrical noise filter system with a control-based system using frequency detection and switching frequency adjustment. This substitution eliminates complex hardware filtering while achieving noise suppression through intelligent frequency management
3Object-affected harmful factors
If the switching frequency is set to a specified frequency different from the selected broadcast station, then noise overlap with broadcast frequency is avoided, but component variations cause switching frequency to vary making consistent avoidance difficult
Solution Approach 1:
The patent implements feedback by continuously detecting broadcast station frequencies and using this information to adjust the switching frequency. The control device monitors the frequency environment and dynamically adjusts switching parameters to maintain avoidance of overlapping, compensating for component variations through active feedback control
Solution Approach 2:
The patent makes the switching frequency dynamic rather than fixed, allowing it to adjust within a predetermined range based on detected broadcast frequencies. This dynamic adjustment ensures consistent frequency avoidance despite component variations
4Object-affected harmful factors
If the switching frequency is set within a narrow frequency band range, then frequency relationship with broadcast stations can be controlled, but the narrow bandwidth makes it difficult to maintain the given relationship due to component variations
Solution Approach 1:
The patent applies dynamics by allowing the switching frequency to vary within a predetermined range rather than being fixed at a single value. This dynamic range accommodates component variations while maintaining frequency avoidance through active detection and adjustment
Solution Approach 2:
The patent changes the switching frequency parameter within a predetermined range based on detected broadcast frequencies. By allowing parameter variation and active adjustment, the system maintains frequency avoidance control despite manufacturing tolerances
Data Source
AI summary
A switching device and a method of operating a switching power element are disclosed for generating a train of drive pulses (D1 to D32) in a basic pattern for a repetition cycle time (T to TF) having leading time intervals (Th1 to Th3, Th1′ to Th3′), associated with leading edges (a1 to a32) of the drive pulses, and trailing time intervals (Tl1 to Tl3, Tl1′ to Tl3′), associated with trailing edges (b1 to b32) of the drive pulses, which are different from each other, whereby switching frequencies and associated harmonics, resulting from the leading edges and the trailing edges of the drive pulses, are diffused. A diffusion frequency, representing an inverse number of the repetition cycle time for the basic pattern is set to be higher than an audible frequency.