Switching Power Supply Frequency Correction for AC Voltage Adaptability
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Solution Overview
Problem
Switching power-supply devices struggle to operate at optimal switching frequencies across varying input voltages, leading to inefficiencies due to a common, pre-set frequency reduction point, which fails to adapt to different commercial AC power voltage systems.
Innovation Solution
A switching power-supply device with a frequency generation circuit, error amplifier, off timing determination circuit, and switching-current-waveform correction circuit that adjusts switching frequency based on input voltage and load conditions, using a controller IC to optimize switching frequency and duty cycle for improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common pre-set frequency reduction point is used for all input voltages, then the device complexity is reduced and ease of manufacture is improved, but the adaptability to different input voltage systems deteriorates and efficiency cannot be optimized
Solution Approach 1:
The patent implements dynamic adjustment of the frequency reduction point based on detected input voltage levels. The control circuit automatically selects different frequency reduction points corresponding to different input voltage ranges (e.g., 100V system vs 200V system), transforming the static common setting into a dynamic adaptive parameter that optimizes switching frequency for each operating condition.
Solution Approach 2:
The patent changes the parameter of frequency reduction point based on input voltage conditions. By detecting the input voltage level and accordingly adjusting the frequency reduction point parameter, the system adapts to different commercial AC power systems (100V or 200V) and maintains optimal efficiency across varying operating conditions.
2Loss of energy
If switching frequency is reduced in light or middle load, then switching loss is reduced and efficiency is improved, but the adaptability to different input voltages deteriorates when using a fixed frequency reduction point
Solution Approach 1:
The patent dynamically changes the frequency reduction point parameter based on both load conditions and input voltage levels. This allows the system to reduce switching frequency and switching loss in light or middle load while adapting the reduction point to the specific input voltage system, thereby maintaining both energy efficiency and adaptability across different operating conditions.
3Device complexity
If a fixed frequency reduction point is used, then the control system complexity is reduced, but the ability to operate at optimal switching frequency for different input voltages deteriorates
Solution Approach 1:
The patent introduces dynamic control where the frequency reduction point automatically adjusts based on detected input voltage levels. This dynamic adaptation enables the system to operate at optimal switching frequencies for different input voltage systems (100V or 200V) without requiring complex manual configuration, thereby improving operational efficiency while maintaining relatively simple control architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables operation at optimal switching frequencies for both 100V and 200V commercial AC power systems, reducing losses and enhancing efficiency by dynamically adjusting switching frequency and duty cycle according to input voltage and load conditions.
Implementation Method 1
applies a DC voltage obtained by rectifying input voltage of AC power source to a primary winding of a transformer and performs a switching operation of a switching element connected to the primary winding of the transformer to generate a pulse voltage on a secondary winding of the transformer
Implementation Method 2
output an output voltage to a load, the output voltage being rectified and smoothed by a rectification and smoothing circuit of a secondary side having a rectifier diode and a smoothing capacitor
Implementation Method 3
output an output voltage to a load, the output voltage being rectified and smoothed by a rectification and smoothing circuit of a secondary side having a rectifier diode and a smoothing capacitor
Data Source
AI summary
A switching power-supply device applies a DC voltage to a primary winding of a transformer and performs a switching operation of a switching element connected to a primary winding to generate and output an output voltage to a load. The switching power-supply device includes: an error amplifier, which compares the output voltage with a reference voltage and sends an error voltage as a feedback signal to a primary side; a frequency generation circuit, which generates a switching frequency according to the feedback signal; an off timing determination circuit, which determines a timing at which the switching element is turned off, by comparing a signal depending on the feedback signal with a current flowing through the switching element; and a frequency correction circuit, which corrects the switching frequency generated by the frequency generation circuit, according to an on-duty of the switching element.