Switch Controller with Zero-Cross Sine Reference for Power Factor Correction
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Solution Overview
Problem
Conventional converters face challenges in improving power factor and total harmonic distortion (THD) due to phase differences between input power voltage and current, leading to power loss and increased production costs from separate power factor correction circuits.
Innovation Solution
A switch controller that generates a reference signal with a frequency and phase similar to the input voltage, using a zero voltage detector, reference clock generator, and digital sine curve generator to synchronize the power switch operation, eliminating the need for a separate power factor correction circuit and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate power factor correction controller circuit is used, then the power factor is corrected, but the production cost increases and integration becomes difficult
Solution Approach 1:
The patent combines the power factor correction control function with the existing switch controller that manages the power switch. By integrating the zero cross detection signal processing and reference signal generation into the same controller, the system eliminates the need for a separate power factor correction controller circuit, thereby reducing production cost and improving integrability while maintaining reliable power factor correction
2Difficulty of detecting and measuring
If a resistor is used to sense the full-wave rectified input power voltage, then the voltage can be detected, but power consumption occurs and high voltage-endurance is required
Solution Approach 1:
The patent replaces the traditional resistive voltage sensing method with a capacitive sensing approach using a first capacitor connected to the full-wave rectified input power voltage. This substitution eliminates the continuous power consumption associated with resistive sensing while removing the high voltage-endurance requirements, as the capacitor can be discharged through a discharge element when not in use
3Power
If the input power voltage is high, then the converter can operate at higher voltages, but it is difficult to integrate high voltage-endurable components
Solution Approach 1:
The patent extracts the high voltage sensing function from the main controller by using a separate capacitive sensing circuit that operates independently at the high voltage level. The capacitor senses the high voltage input and provides isolated sensing signals to the controller, allowing the main controller to operate at lower voltages and improving integrability while still enabling high voltage operation
Data Source
AI summary
Disclosed are a switch controller, a switch control method, and a converter based thereon. The switch controller generates an input sensing voltage corresponding to the input voltage of the converter, and compares the input sensing voltage with a predetermined first reference value. The switch controller generates a zero cross detection signal with a first level or a second level depending upon the comparison result, and generates a reference clock signal varying in frequency in accordance with one cycle of the zero cross detection signal. The switch controller generates digital signals by using the reference clock signal and the zero cross detection signal. The digital signals synchronize with the zero cross detection signal, and increase in accordance with the reference clock signal during a half of one cycle of the zero cross detection signal, while decreasing in accordance with the reference clock signal during the other half cycle of the zero cross detection signal. The switch controller generates a reference signal with a voltage level corresponding to the digital signal.