PFC Switching Control for Lower Peak Inductor Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power supply apparatuses with CRM-based PFC circuits face limitations in efficiency due to high peak inductor currents, which can lead to increased inductor size and conduction losses, making it difficult to comply with harmonic standards like IEC 61000-3-2.
Innovation Solution
A power supply apparatus with a PFC circuit that includes a control circuit to alternately turn on/off switching elements, using a sensing resistor and error amplifier to manage inductor current, reducing peak current and inductor size through controlled switching and synchronous rectification, thereby minimizing conduction and switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If CRM-based PFC circuit is used, then power factor correction is achieved, but peak inductor current increases causing increased inductor size and conduction losses
Solution Approach 1:
The patent applies dynamics by transitioning from static CRM-based switching to dynamic controlled switching of the second switching element. The control circuit dynamically adjusts the switching timing based on inductor current feedback, enabling the circuit to operate optimally across varying load conditions and minimize peak currents without requiring larger inductors.
Solution Approach 2:
The patent implements feedback by using the sensing resistor to detect inductor current and feeding this information back to the control circuit. The control circuit uses this feedback to regulate the switching of the second switching element, maintaining optimal current levels and preventing excessive peak currents that would require larger inductors and increase conduction losses.
2Loss of energy
If inductor size is reduced to minimize conduction losses, then efficiency improves, but peak inductor current increases causing harmonic compliance issues
Solution Approach 1:
The feedback mechanism monitors inductor current and provides real-time control adjustment to the second switching element, enabling the system to maintain low peak currents that satisfy harmonic standards while keeping inductor size small and conduction losses minimal.
Solution Approach 2:
The patent changes the operational parameters by introducing controlled switching of the second switching element with adjustable timing. This parameter adjustment allows the circuit to optimize the balance between peak current suppression (for harmonic compliance) and conduction loss minimization (for efficiency), independent of inductor size.
3Productivity
If controlled switching of second switching element is implemented, then peak current is reduced and efficiency maximized, but device complexity increases
Solution Approach 1:
The control circuit is designed with multi-functionality, serving both to regulate the second switching element for peak current reduction and to maintain power factor correction. This universal approach consolidates control functions rather than adding separate circuits, minimizing the increase in device complexity while achieving improved efficiency.
Solution Approach 2:
The sensing resistor provides self-service by automatically generating the feedback signal needed for control without requiring additional sensing circuits. The existing current path through the sensing resistor is utilized to provide the necessary control information, reducing the complexity overhead of the control mechanism.
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
The solution reduces inductor size and maximizes efficiency while meeting harmonic standards, improving power factor correction and reducing losses in the power supply apparatus.
Implementation Method 1
a sensing resistor and error amplifier to manage inductor current
Implementation Method 2
error amplifier to manage inductor current
Implementation Method 3
a first switching element configured to be turned on and turned off, according to a first control signal
Data Source
AI summary
The present disclosure provides power supply apparatuses and controlling methods thereof. In some embodiments, a power supply apparatus includes a power factor correction (PFC) circuit, and a control circuit configured to control the PFC circuit. The PFC circuit includes a power inputter configured to receive alternating current voltage to be rectified, an inductor having an end coupled to an end of the power inputter, a first switching element configured to be turned on and off according to a first control signal, a second switching element configured to be turned on and off according to a second control signal, and an outputter configured to output a direct current voltage through an output capacitor. The control circuit is further configured to respectively apply the first and second control signals to the first and second switching elements such that the first and the second switching elements are alternately turned on.