One-Pin Power Factor Correction Circuit for Lighting
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Solution Overview
Problem
Existing power factor correction circuits for AC/DC converters in lighting devices require multiple sensor pins, which increase costs and space requirements, and fail to effectively minimize harmonics and interference frequencies.
Innovation Solution
A power factor correction circuit that uses a single sensor PIN to generate switching signals by evaluating a sensor voltage composed of output or input voltage and a differential voltage, allowing the control unit to compensate one voltage component, thereby reducing the number of necessary sensor pins and minimizing harmonic reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensor pins are used to monitor input voltage, discharge current, charging current, and intermediate circuit voltage, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple sensor signals (input voltage, discharge current, charging current, intermediate circuit voltage) into a single sensor pin by using a differential voltage measurement approach. The control unit calculates all necessary voltage and current parameters by evaluating the differential voltage between two points in the circuit, eliminating the need for separate sensor pins for each parameter.
Solution Approach 2:
The single sensor pin serves multiple functions by providing a differential voltage measurement that enables the control unit to derive all necessary control information (input voltage level, discharge current, charging current, intermediate circuit voltage) from this single measurement point, making the sensor pin universal for all monitoring purposes.
2Reliability
If multiple sensor pins are used for comprehensive monitoring, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple sensing functions into a single sensor pin connection, reducing the bill of materials and assembly complexity. The differential voltage measurement approach maintains comprehensive monitoring capability while using fewer physical components, thereby improving ease of manufacture and reducing cost.
Solution Approach 2:
The circuit uses existing circuit nodes (connection point between inductance and diode, and ground) to provide the differential voltage measurement, rather than requiring separate dedicated sensing paths. This self-service approach leverages the existing circuit structure to provide all necessary measurement information through a single pin.
3Device complexity
If simple voltage monitoring is used with a single sensor pin, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces a differential voltage measurement as an intermediary that captures multiple circuit parameters simultaneously. By measuring the voltage difference between two strategically chosen points (connection point between inductance and diode, and ground), the system obtains information about input voltage, discharge current, charging current, and intermediate circuit voltage through a single measurement.
Solution Approach 2:
The patent changes the measurement parameter from individual voltage or current measurements to a differential voltage measurement that encompasses multiple parameters. The control unit processes this differential voltage signal to extract all necessary control information, maintaining measurement precision while simplifying the sensor configuration.
4Manufacturing precision
If conventional multi-pin sensor configuration is used, then control accuracy is improved, but space requirements increase
Solution Approach 1:
The patent merges multiple sensor pin connections into a single pin, reducing the space required on the circuit board for pin connections and associated routing. The differential voltage measurement approach maintains all necessary control accuracy while requiring minimal physical space for the sensing connection.
Data Source
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AI summary
The invention relates to a method and to a circuit for power factor correction in an alternating current/direct current power converter. The circuit has an inductor (L), which is fed by a rectified alternating voltage (vin), furthermore a switch (Sw), by means of which the inductor (L) can be charged and discharged by closing and opening same, and a diode (D), by means of which the discharge current of the inductor (L) can be supplied to the output of the circuit. The switch (Sw) is controlled by a control unit (PFC) having a single PIN sensor (PINsens), which is supplied with a sensor signal (vsens) consisting of two superimposed voltage components (vR2, vWs). The one voltage component (vR2) is withdrawn from a voltage divider, and the other voltage component (vWs) is withdrawn from the secondary winding (Ws) of a transformer, the primary winding (Wp) of which is formed by the inductor. The voltage divider (R1, R2) and the secondary winding (Ws) of the transformer are connected in series. The voltage divider ratio (R1/R2) and the winding ratio (Wp/Wp) of the transformer are equal to each other (k).