PFC-Boost Power Supply Circuit for Higher Density Holdup
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Solution Overview
Problem
Conventional power supply circuits face challenges with large-sized inductors and capacitors that limit power density and conversion efficiency, while maintaining sufficient holdup time and high power conversion efficiency.
Innovation Solution
A power supply circuit design incorporating a power factor correction (PFC) circuit with a first storage capacitor and a boost conversion circuit, utilizing smaller capacitors and transistors to transfer energy efficiently, reducing the size of components and increasing power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If large-sized inductor L_pf and capacitor C_bk are used in the PFC circuit, then the holdup time of electrical energy is sufficient, but the power density of the power supply circuit is limited
Solution Approach 1:
The patent divides the single large capacitor C_bk into multiple smaller capacitors (C1, C2, C3, C4) with individual capacitances of 4.7μF each. This segmentation allows the total capacitance (18.8μF) to be achieved while reducing the physical size and improving power density, as multiple small capacitors occupy less space than one large capacitor of equivalent capacitance.
Solution Approach 2:
The patent implements a nested capacitor configuration where multiple capacitors are arranged in a compact nested structure. The capacitors are positioned within each other's spatial envelope, allowing them to share magnetic shielding space and reduce overall component footprint, thereby increasing power density while maintaining sufficient holdup time.
2Device complexity
If conventional bridge circuit with diodes D1 ̃D4 is used, then the circuit structure is simple, but the voltage drop of diodes limits the conversion efficiency
Solution Approach 1:
The patent replaces the mechanical diode-based bridge circuit with an active switch network consisting of transistors (Q1-Q4) and control circuitry. This substitution eliminates the inherent voltage drop of diodes (typically 0.7V per diode) by using low-on-resistance MOSFETs that can be actively controlled, thereby significantly reducing conduction losses and improving overall conversion efficiency while maintaining circuit functionality.
3Power
If smaller capacitor C_bs is used in the boost conversion circuit, then the power density is increased, but the holdup time may be compromised
Solution Approach 1:
The patent merges the energy storage function of the traditional large capacitor C_bs with the segmented capacitors C1-C4 from the PFC stage. By coordinating the operation of these capacitors and using active control to manage energy transfer, the system achieves sufficient holdup time without requiring a large C_bs capacitor, thereby increasing power density while maintaining energy availability during transient conditions.
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 design achieves reduced hardware cost and increased power density without compromising holdup time, by using smaller capacitors and transistors with higher switching speeds to minimize voltage ripples.
Implementation Method 1
The first storage capacitor has a first end and a second end, wherein the second end is connected to an output end of the PFC circuit, and the first storage capacitor is used to store a first electrical energy related to the intermediate voltage
Implementation Method 2
The second storage capacitor has a first end connected to an first end of the first post-stage diode and a second end connected to a second terminal of the first post-stage transistor, wherein the second storage capacitor is used to store the second electrical energy related to the output voltage
Implementation Method 3
The first post-stage inductor has a first end connected to the first end of the first storage capacitor and a second end connected to a second end of the first post-stage diode
Data Source
AI summary
A power supply circuit includes a power factor correction (PFC) circuit used to perform a power factor correction to generate an intermediate voltage. A first storage capacitor is connected to an output end of PFC circuit and is used to store a first electrical energy related to the intermediate voltage. A boost conversion circuit is connected to the PFC circuit and used to generate an output voltage according to the intermediate voltage. The boost conversion circuit includes a first post-stage inductor, a first post-stage diode, a first post-stage transistor and a first switch. A second storage capacitor is used to store a second electrical energy related to the output voltage. The capacitance value of the second storage capacitor is less than the capacitance value of the first storage capacitor; the first electrical energy is completely or partially transferred as the second electrical energy.