Bidirectional Power Factor Correction Circuit for V2X Applications
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Solution Overview
Problem
Conventional power factor correction circuits are limited to unidirectional power transfer, preventing the implementation of vehicle-to-everything (V2X) applications by not being able to provide battery power externally.
Innovation Solution
A power factor correction circuit with multiple legs connected in parallel, each containing two switching devices in series and inductors, controlled by a controller that uses pulse width modulation and comparators to manage the on/off states based on AC voltage comparisons with a sawtooth wave, enabling bidirectional power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional power factor correction circuit with a diode is used, then the circuit structure is simple, but the power transfer is limited to unidirectional only
Solution Approach 1:
The patent replaces the conventional diode with an active switching circuit that can operate in reverse direction. By using switching devices (MOSFETs or IGBTs) controlled by gate signals instead of a passive diode, the circuit enables bidirectional power flow while maintaining the boost converter topology. This inversion of the unidirectional diode function to a controllable bidirectional switch resolves the contradiction between simplicity and versatility.
Solution Approach 2:
The patent introduces dynamic control through pulse width modulation (PWM) of the switching devices. The switching elements can dynamically adjust their on/off states based on control signals, enabling the circuit to operate in both forward and reverse directions as needed. This dynamic switching capability transforms the static unidirectional power flow into a flexible bidirectional system, achieving adaptability without excessive complexity.
2Volume of moving object
If the inductor inductance is reduced to half, then the inductor size becomes smaller, but the switching frequency and control complexity increase
Solution Approach 1:
The patent employs periodic switching action with a sawtooth wave comparator to generate PWM control signals. The switching devices are turned on and off at regular intervals based on the comparison between the AC voltage and the sawtooth wave, creating a periodic control pattern. This periodic switching enables the inductor to be built up twice per switching period, allowing for reduced inductance values while maintaining stable operation through the regular timing pattern.
Solution Approach 2:
The patent uses a feedback mechanism where the AC voltage is continuously compared with a sawtooth wave reference signal. The comparator generates PWM control signals based on this comparison, automatically adjusting the switching duty cycle to maintain proper inductor current ripple and power factor correction. This feedback control simplifies the management of reduced inductance by automatically adapting the switching parameters, offsetting the increased control complexity with an intuitive voltage-comparison-based approach.
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 bidirectional power transfer, reducing inductor inductance by half, allowing for a smaller inductor size and enabling the conversion of both AC to DC and DC to AC power, thus supporting V2X applications.
Implementation Method 1
a controller configured to control on/off states of the switching devices in a pulse width modulation manner such that each of the inductors is built up twice or more in one switching period of the switching devices
Implementation Method 2
each including two switching devices connected in series, a plurality of inductors each having one terminal connected to an interconnection node of the two switching devices in a corresponding one of the legs
Data Source
AI summary
Disclosed is a power factor correction circuit including a plurality of legs connected in parallel and each leg including two switching devices connected in series, a plurality of inductors, each inductor having one terminal connected to an interconnection node of the two switching devices in a corresponding one of the plurality of legs, and a controller configured to control on/off states of the switching devices of the plurality of legs in a pulse width modulation manner such that each of the inductors of the plurality of inductors is built up twice or more in one switching period of the switching devices when an alternating current (AC) voltage is input to the other terminal of each inductor of the plurality of inductors.