Power Factor Correction Circuit Input Voltage Estimation
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Solution Overview
Problem
Conventional power factor correction circuits require additional pins and consume power to sense input voltage, which is inefficient and increases power consumption.
Innovation Solution
A power factor correction circuit that estimates input voltage without additional pins by using a power factor correction controller with an input voltage information generator, which includes a discharge switch, charge switch, capacitor, and error amplifier to control the switching operation of a power switch based on output and inductor voltages, eliminating the need for explicit input voltage sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If input voltage sensing is implemented using additional pins and resistors, then input voltage information can be obtained for control, but power consumption increases and device complexity increases
Solution Approach 1:
The system uses its own internal operating parameters (switching duty cycle, inductor voltage, output voltage) to derive input voltage information without external sensing components. The controller calculates input voltage based on the relationship Vin = Vout/(1-D) where D is the duty cycle, eliminating the need for separate voltage sensing circuits and reducing power consumption.
Solution Approach 2:
The existing control circuit components that manage switching operations are made to perform dual functions: both controlling the power switch and simultaneously providing input voltage estimation. The same controller that regulates output voltage also derives input voltage information from duty cycle measurements, reducing the need for dedicated sensing hardware.
2Loss of information
If input voltage sensing is implemented using additional pins and resistors, then input voltage information can be obtained for control, but device complexity increases
Solution Approach 1:
The input voltage sensing function is extracted from the traditional external sensing approach and integrated into the existing controller through calculation. Instead of adding external sensing pins and resistor dividers, the system extracts input voltage information from internal operating parameters already being measured for control purposes.
Solution Approach 2:
The input voltage estimation function is merged with the existing output voltage control functionality. The controller simultaneously performs output voltage regulation and input voltage estimation using the same hardware resources, combining multiple functions into a unified control process that reduces overall device complexity.
3Measurement precision
If conventional power factor correction circuit is used with additional sensing components, then input voltage can be sensed, but the circuit requires more components and power consumption
Solution Approach 1:
The physical sensing system (resistors, voltage dividers, external pins) is replaced with a computational approach. Instead of measuring input voltage directly through hardware sensing, the system substitutes a mathematical calculation based on duty cycle and output voltage measurements, eliminating the need for additional sensing components while maintaining control accuracy.
Data Source
AI summary
A power factor correction circuit includes an inductor, a power switch, and a power factor correction controller. The power factor correction controller receives information on an inductor voltage to control a switching operation of the power switch. The power factor controller estimates an input voltage according to the duty ratio of the power switch.