Switching Power Supply Timing Control for Noise Suppression
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Solution Overview
Problem
Switching power supply devices generate noise that affects the outside environment due to simultaneous switching of switches, which is not effectively suppressed in existing configurations.
Innovation Solution
A configuration where a controller shifts the timing of switching from off to on between pairs of switches, with controlled slew rates for switch control signals, reducing switching losses and noise propagation by managing the switching of first and fourth switches independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two switches in a pair are simultaneously switched from off to on at the same timing, then the switching power supply device operates efficiently, but noise is generated that affects the outside environment
Solution Approach 1:
The patent applies preliminary action by switching one switch (e.g., third switch) before the other switch (e.g., first switch) in the same pair. This sequential switching approach prepares the circuit state in advance, allowing the second switch to turn on when voltage stress is reduced, thereby suppressing noise while maintaining efficient power conversion.
2Device complexity
If switches are switched simultaneously, then the control circuit is simple, but switching losses increase and noise propagates externally
Solution Approach 1:
The control circuit implements preliminary action by generating control signals that switch the third switch before the first switch. This timing arrangement reduces the voltage across switching elements during transitions, minimizing switching losses while adding only minimal complexity to the control logic.
3Speed
If the slew rate of switch control signals is increased, then the switching speed improves, but noise generation increases
Solution Approach 1:
The patent applies local quality by differentiating the slew rates of control signals for different switches. The third switch control signal has a higher slew rate for faster switching, while the first switch control signal has a lower slew rate to suppress noise. This localized optimization of signal characteristics resolves the contradiction between switching speed and noise generation.
Data Source
AI summary
A switching power supply device includes first to fourth switches sequentially connected in series, an inductor, a first capacitor whose first end is connected to a connection node of the first switch and the second switch and whose second end is connected to a connection node of the third switch, the fourth switch, and the inductor, a second capacitor whose first end is connected to a connection node of the second switch and the third switch, and a controller that controls switching on and off of the first to fourth switches. In at least one of a first pair configured with the first switch and the third switch and a second pair configured with the second switch and the fourth switch, the controller shifts a timing of switching from off to on between two switches.