Switching Power Supply Circuit Harmonic Control
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Solution Overview
Problem
Conventional switching power supply circuits that combine power factor improvement and frequency hopping functions often deteriorate harmonic characteristics, particularly even order harmonics, when both functions are independently mounted.
Innovation Solution
A switching power supply circuit that includes an output transistor, an oscillator generating a varying switching frequency synchronized with the AC input voltage, a controller for power factor adjustment, and a logic circuit to generate switch control signals, ensuring both power factor improvement and frequency hopping without degrading harmonic characteristics by synchronizing the frequency hopping operation with the AC input voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both power factor improvement function and frequency hopping function are independently mounted in conventional switching power supply circuit, then both functions can be achieved, but even order harmonic characteristics are deteriorated
Solution Approach 1:
The patent combines the power factor improvement function and frequency hopping function into a unified control architecture where the controller integrates both control algorithms. The controller simultaneously generates PWM signals for power factor correction and modulates switching frequency for EMI reduction, eliminating the need for independent mounting of separate control circuits while preventing harmonic deterioration through coordinated control.
Solution Approach 2:
The controller is designed as a multi-functional unit that performs both power factor improvement control and frequency hopping control. By making the controller universal, it can handle multiple functions through integrated control logic, avoiding the harmonic distortion issues that arise from independent control circuits operating without coordination.
2Adaptability or versatility
If both power factor improvement function and frequency hopping function are independently mounted in conventional switching power supply circuit, then both functions can be achieved, but electromagnetic interference suppression is reduced due to harmonic deterioration
Solution Approach 1:
The patent merges the frequency hopping function with power factor improvement control in a unified controller. The controller simultaneously executes frequency modulation for EMI suppression and power factor correction, ensuring that frequency hopping does not create harmful harmonics that would counteract the EMI suppression benefits.
Solution Approach 2:
The integrated controller uses feedback mechanisms to monitor both power factor performance and switching frequency. By continuously adjusting control parameters based on feedback, the system maintains optimal frequency hopping patterns that suppress EMI while preventing harmonic deterioration, thereby enhancing overall EMI suppression effectiveness.
Data Source
AI summary
Provided is a switching power supply circuit including an output transistor arranged to be turned on and off to generate a desired output voltage from a pulsating voltage obtained by rectifying an AC input voltage, an oscillator arranged to generate an ON signal at a switching frequency varying periodically in synchronization with the AC input voltage or the pulsating voltage, a controller arranged to generate an OFF signal so that the output voltage is adjusted to a target value while a power factor becomes close to one, a logic circuit arranged to generate a switch control signal in accordance with the ON signal and the OFF signal, and a driver arranged to turn on and off the output transistor in accordance with the switch control signal.