PFC Converter Ripple Compensation Circuit for EV Battery Charging
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Solution Overview
Problem
Conventional electric vehicle battery charging devices require high-capacitance electrolytic capacitors for power factor correction, which have short lifespans at high temperatures and are not suitable for applications needing long lifespan, and film capacitors offer lower power density, making them unsuitable for high-capacitance and high-power density requirements.
Innovation Solution
A device with a ripple compensation part that includes a first and second switching element, a compensation inductor, and a compensation capacitor, connected in a specific configuration to reduce ripple voltage in the output voltage of a PFC converter, allowing for effective ripple voltage compensation without using high-capacitance electrolyte capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-capacitance electrolyte capacitors are used for filtering fluctuating power in PFC converter, then power density and capacitance requirements are met, but lifespan decreases rapidly at high temperatures
Solution Approach 1:
The invention divides the single capacitor filtering function into two separate components: a first capacitor (C1) for basic filtering and a second capacitor (C2) for supplementary filtering. This segmentation allows each capacitor to operate within optimal parameters, with the film capacitor (C2) providing extended lifespan while the electrolyte capacitor (C1) maintains high power density capability.
Solution Approach 2:
The invention creates a composite capacitor system combining two different capacitor technologies (electrolyte and film) with complementary characteristics. The electrolyte capacitor provides high power density while the film capacitor provides high reliability and temperature stability, achieving a composite solution that surpasses either component alone.
2Reliability
If film capacitors are used instead of electrolyte capacitors, then lifespan is extended, but power density decreases significantly
Solution Approach 1:
The filtering function is segmented between two capacitor types, allowing the film capacitor to contribute its lifespan advantage while the electrolyte capacitor contributes its power density advantage, resolving the trade-off between these two properties.
Solution Approach 2:
The invention merges two capacitor technologies with different strengths into a parallel configuration, combining the lifespan advantage of film capacitors with the power density advantage of electrolyte capacitors to achieve both properties simultaneously.
3Adaptability or versatility
If dual composition structure with PFC converter and high-voltage link capacitor is used, then wide output range is achieved, but device complexity increases
Solution Approach 1:
The dual composition structure is segmented into functionally distinct modules: PFC converter for power factor correction, first capacitor for basic filtering, second capacitor for ripple compensation, and DC/DC converter for voltage regulation. This modular segmentation makes the complex system more manageable and maintainable.
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 effectively reduces ripple voltage in the output voltage of the PFC converter, achieving the same performance as high-capacitance electrolyte capacitors with lower-capacity film capacitors, thereby extending the lifespan and improving power density in electric vehicle charging devices.
Implementation Method 1
a compensation inductor having one end connected with the other end of the first switching element and with one end of the second switching element
Implementation Method 2
a compensation capacitor having one end connected with the other end of the inductor and having the other end connected with a ground
Implementation Method 3
a first switching element having one end connected with an output terminal that is not connected with a ground from among two output terminals forming an output end of the PFC converter; a second switching element having one end connected with the other end of the first switching element and having the other end connected with a ground
Data Source
AI summary
A device for compensating ripples in the output voltage of a PFC converter and a battery charging device for an electric vehicle are disclosed. The disclosed device for compensating the ripples included in the output voltage of a PFC converter includes: a first switching element having one end connected with an output terminal that is not connected with a ground from among two output terminals forming an output end of the PFC converter; a second switching element having one end connected with the other end of the first switching element and having the other end connected with a ground; a compensation inductor having one end connected with the other end of the first switching element and with one end of the second switching element; and a compensation capacitor having one end connected with the other end of the compensation inductor and having the other end connected with a ground.