Power Factor Correction Circuit Using Resistor-Based Current Sensing
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Solution Overview
Problem
Existing power factor correction circuits require costly current sampling devices to control inductive branches, leading to high overall costs.
Innovation Solution
A power factor correction circuit with parallel power regulation branches, inductive branches, a rectifier branch, and a capacitance branch, where branch sampling resistors and a main line sampling resistor are used to indirectly sample currents, reducing the need for expensive current sampling devices by employing a control method that adjusts switching units based on sampled branch and main line currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall circuits are used to collect current of each inductive branch, then current sampling accuracy is improved, but system cost increases
Solution Approach 1:
The patent extracts the current sampling function from expensive Hall circuits and implements it using simple resistors. Instead of using Hall effect sensors for each inductive branch, the invention uses branch sampling resistors connected in series with each branch, which generate voltage signals proportional to branch currents that can be read by the control circuit. This extraction principle replaces complex sensing devices with simple passive components while maintaining the essential measurement function.
Solution Approach 2:
The patent employs inexpensive resistors as sampling elements instead of costly Hall circuits. The branch sampling resistors and main line sampling resistor are simple, cheap passive components that fulfill the current measurement requirement through voltage division, eliminating the need for expensive active sensing devices. This principle trades measurement sophistication for cost-effectiveness while achieving sufficient accuracy for control purposes.
2Reliability
If current sampling of each inductive branch is implemented, then current sharing control is improved, but device complexity increases
Solution Approach 1:
The patent makes the main line sampling resistor serve multiple functions: it samples the total current from all parallel branches and provides a reference for current sharing control. Instead of requiring separate sampling devices for each branch's total current measurement, this single resistor performs the universal sampling function for the entire parallel circuit, reducing component count while maintaining control capability.
Solution Approach 2:
The patent introduces voltage signals as an intermediary medium between the current-carrying branches and the control circuit. The branch sampling resistors and main line sampling resistor convert currents into voltage signals that are easier to process and compare. This intermediary transformation simplifies the control circuit's task of achieving current sharing by working with voltage ratios rather than direct current measurements.
Data Source
AI summary
The present disclosure relates to a power factor correction circuit, a control method, and an electrical appliance. The power factor correction circuit may include: a power regulation branch, including a first switching unit, a second switching unit and a branch sampling resistor connected in series sequentially; an inductive branch, connected between an AC power source and a power regulation branch; a rectifier branch, including a first rectifier unit and a second rectifier unit, the rectifier branch may include a main line sampling resistor; a capacitance branch; a control circuit sampling a branch current flowing through each of the branch sampling resistors and a main line current flowing through the main line sampling resistor respectively, and controlling the switching of each power regulation branch sequentially. With the branch sampling resistor and the main line sampling resistor, the overall cost of the power factor correction circuit may be reduced.