Inductor Current Detection in Critical-Conduction Mode PFC Circuits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Critical-conduction mode Power Factor Correction (PFC) circuits face challenges in timely and accurate detection of inductor current signals necessary for loop control and protection functions.
Innovation Solution
A method and device that detect voltage on a boost inductor of a critical-conduction mode PFC circuit, converting the inductor voltage detection signal into a waveform consistent with the current waveform to serve as an inductor current detection signal, using techniques such as sense resistors or auxiliary windings for voltage detection and integral processing to achieve accurate current representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage detection method is used on boost inductor, then inductor current detection can be realized, but waveform consistency with current signal is not achieved
Solution Approach 1:
The patent applies parameter changes by transforming the detected voltage signal through integral processing to obtain a current waveform. The voltage detection signal is integrated over time and scaled to produce a detection signal whose waveform matches the actual inductor current waveform, thereby resolving the waveform inconsistency issue while maintaining detection accuracy
Solution Approach 2:
The patent introduces an intermediary processing stage between voltage detection and current representation. The integral circuit acts as an intermediary that converts the voltage signal into a current-equivalent signal, serving as a mediator that bridges the gap between voltage measurement and current waveform representation
2Measurement precision
If direct current detection is implemented in critical-conduction mode PFC circuit, then accurate current signal can be obtained, but detection complexity increases
Solution Approach 1:
The patent uses voltage detection as an intermediary approach instead of direct current detection. By measuring the voltage across the boost inductor and transforming it through integral processing, the system obtains accurate current information without the complexity of direct current sensing circuits
Solution Approach 2:
The patent substitutes direct electrical current measurement with a voltage measurement approach followed by mathematical transformation. This replacement simplifies the detection circuit by using voltage sensing (which is inherently simpler) instead of complex current sensing arrangements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the realization of inductor current detection in critical-conduction mode PFC circuits, facilitating effective loop protection and over-current protection by providing a signal that accurately represents the inductor current waveform.
Implementation Method 1
an auxiliary winding is added and enwound on a PFC inductor... through electromagnetic coupling, a positive voltage corresponding to a rising waveform of the current of the boost inductor
Implementation Method 2
converting the inductor voltage detection signal into a voltage signal whose waveform is consistent with a current waveform of the inductor to serve as an inductor current detection signal
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A method and device for detecting inductor current of a PFC circuit are disclosed, which relates to the field of power supply technology. The method includes: detecting a voltage on a boost inductor of a critical-conduction mode PFC circuit, and obtaining an inductor voltage detection signal (S1); converting the inductor voltage detection signal into a voltage signal whose waveform is consistent with a current waveform of the inductor to serve as an inductor current detection signal, to perform loop protection on the PFC circuit or perform over-current protection on the PFC circuit by using the inductor current detection signal (S2). In the above technical scheme, through the method for detecting the inductor voltage of the critical-conduction mode PFC circuit and indirectly obtaining the inductor current, the function of detecting the inductor current of the critical-conduction mode PFC circuit can be realized, and loop control on the system or protection control on the inductor current peak value can be achieved by using the detected inductor current of the PFC circuit.