Switching Power Supply Frequency Control for Ripple Reduction
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Solution Overview
Problem
Switching power supplies face issues with high output ripple voltage and increased switching loss at varying input voltages and frequencies, leading to potential malfunctions and inefficiencies.
Innovation Solution
A switching power supply with a frequency setting unit that adjusts the lower limit of the switching frequency variation range based on input voltage thresholds, combined with a signal generator to vary the switching frequency, reduces output ripple voltage and minimizes switching noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching frequency is lowered to reduce switching loss, then conversion efficiency is improved, but output ripple voltage becomes large
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The frequency setting unit dynamically adjusts the switching frequency based on the input voltage level: using a first (lower) switching frequency when input voltage is below the threshold to minimize switching loss, and a second (higher) switching frequency when input voltage exceeds the threshold to reduce output ripple voltage. This dynamic adaptation resolves the contradiction between switching loss and output ripple voltage.
Solution Approach 2:
The patent changes the parameter of switching frequency based on input voltage conditions. By setting different frequency ranges (first frequency range below threshold, second frequency range above threshold), the system optimizes performance for different operating conditions. This parameter change strategy allows the system to achieve low switching loss at low frequencies while preventing excessive output ripple at high frequencies.
2Reliability
If the switching frequency is raised to reduce output ripple voltage, then output ripple voltage is reduced, but switching loss increases
Solution Approach 1:
The system dynamically selects switching frequency based on real-time input voltage detection. When input voltage exceeds the predetermined threshold, the frequency setting unit raises the switching frequency to reduce output ripple voltage. When input voltage is below the threshold, it lowers the switching frequency to minimize switching loss. This dynamic control resolves the contradiction by applying high frequency only when necessary.
Solution Approach 2:
The patent implements parameter changes by establishing a threshold-based frequency selection mechanism. The frequency setting unit changes the switching frequency parameter according to whether the input voltage is above or below the threshold, enabling the system to optimize between output ripple voltage and switching loss based on operating conditions.
3Object-affected harmful factors
If spectrum spreading is performed with a wide frequency variation range to suppress switching noise, then electromagnetic interference is reduced, but output ripple voltage increases at high input voltages
Solution Approach 1:
The patent applies dynamics by making the frequency variation range adaptive rather than fixed. The frequency setting unit dynamically adjusts the center frequency of the variation range based on input voltage: using a first center frequency (lower) when input voltage is below threshold and a second center frequency (higher) when input voltage exceeds threshold. This dynamic adjustment suppresses switching noise through spectrum spreading while preventing excessive output ripple voltage by raising the frequency baseline at high input voltages.
Solution Approach 2:
The patent changes the parameter of frequency variation range based on input voltage conditions. By setting different center frequencies for the spectrum spreading function according to whether input voltage is above or below the threshold, the system optimizes both electromagnetic interference suppression and output ripple voltage control simultaneously.
Data Source
AI summary
The switching power supply is provided with a voltage converter including a switching element for inputting a voltage from an input terminal, and has a spread spectrum function of varying a switching frequency in the switching element within a predetermined variation range. The switching power supply has a frequency setting unit that sets the variation range of the switching frequency and raises a lower limit value of the set variation range when a value of the voltage input from the input terminal is equal to or more than a predetermined threshold, and a signal generator that generates a control signal for driving the switching element by varying the switching frequency within the variation range set by the frequency setting unit.