Power Factor Correction Circuit with Voltage Adjustment for Wide Input Range
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Solution Overview
Problem
Conventional power factor correction circuits experience reduced accuracy and deteriorated power factor when handling a wide range of AC input voltages, due to variations in current sensing and loop gain, leading to distorted output currents and reduced responsiveness.
Innovation Solution
A power factor correction circuit with a voltage adjustment circuit that detects input voltage and adjusts sensing voltages accordingly, maintaining proper loop gain and current sensing accuracy across different AC input voltages by using a voltage adjustment circuit to control switching elements in the boost chopper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed current sensing circuit is used without voltage adjustment, then the circuit structure is simple, but the current sensing accuracy deteriorates when input voltage varies widely
Solution Approach 1:
The patent applies dynamics by making the current sensing circuit adjustable based on input voltage conditions. The voltage adjustment circuit dynamically changes the sensing voltage according to the detected input voltage level, allowing the system to adapt to wide voltage ranges (85V-264V AC) while maintaining accurate current sensing across all operating conditions.
Solution Approach 2:
The patent changes the sensing voltage parameter based on input voltage detection. When high input voltage is detected, the voltage adjustment circuit reduces the sensing voltage to prevent saturation and maintain accuracy. This parameter adjustment resolves the contradiction between simple fixed circuit design and accurate sensing across varying voltage conditions.
2Measurement precision
If the voltage adjustment circuit is added to maintain sensing accuracy, then the current sensing accuracy improves, but the device complexity increases
Solution Approach 1:
The patent introduces a voltage adjustment circuit as an intermediary between the input voltage detection and the current sensing circuit. This mediator component detects the input voltage level and appropriately adjusts the sensing voltage before it reaches the sensing circuit, thereby improving accuracy without requiring complete redesign of the sensing architecture.
Solution Approach 2:
The voltage adjustment circuit serves multiple functions: it detects input voltage levels, determines appropriate sensing voltage adjustments, and controls the switching elements to implement the adjustment. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall device complexity.
3Measurement precision
If the sensing voltage is increased for high input voltage operation, then the current sensing accuracy improves, but the loop gain becomes excessive causing distorted output currents
Solution Approach 1:
The patent applies preliminary anti-action by detecting high input voltage conditions in advance and preemptively reducing the sensing voltage before it can cause excessive loop gain. The voltage adjustment circuit proactively compensates for the potential harmful effect of high input voltage on the sensing circuit, preventing output current distortion before it occurs.
Solution Approach 2:
The patent uses feedback by having the voltage adjustment circuit continuously monitor the input voltage level and adjust the sensing voltage accordingly. This closed-loop control ensures that the sensing voltage remains at an appropriate level regardless of input voltage variations, preventing both accuracy loss and excessive loop gain conditions that would distort output currents.
4Stability of the object's composition
If the sensing voltage is reduced for low input voltage operation, then the loop gain is reduced improving stability, but the current sensing accuracy deteriorates
Solution Approach 1:
The patent applies dynamics by making the sensing voltage adjustable based on detected input voltage levels. For low input voltage operation, the voltage adjustment circuit increases the sensing voltage to maintain adequate loop gain and stability while preserving current sensing accuracy. This dynamic adjustment resolves the contradiction between stability and accuracy in low voltage conditions.
Data Source
AI summary
To provide a power factor correction circuit capable of maintaining loop gain properly while maintaining current sensing accuracy even when different AC input voltages are input and a switching power source device using the power factor correction circuit. A power factor correction circuit includes: a power factor correction control circuit including an input voltage detection terminal to which voltage corresponding to input voltage to a boost chopper is input, a current sensing terminal to which voltage corresponding to inductor current in the boost chopper is input, an output voltage detection terminal to which voltage corresponding to output voltage from the boost chopper is input, and an output terminal outputting a drive signal for a switching element; and a voltage adjustment circuit configured to detect the input voltage and adjust voltage at the current sensing terminal and voltage at the input voltage detection terminal according to the detected input voltage.