Ripple Pacifier for DC-Link Voltage Stabilization
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Solution Overview
Problem
Existing DC power systems face challenges in stabilizing DC-link voltage due to ripple oscillations caused by AC/DC or DC/AC conversions, leading to efficiency degradation, heat issues in EV batteries, and reduced power efficiency in photovoltaic applications, with conventional solutions requiring modifications to existing hardware or compromising on power factor and harmonics distortion.
Innovation Solution
A plug-and-play Ripple Pacifier (RP) device that absorbs ripple power at the DC-link interface, eliminating the need for electrolytic capacitors and allowing for stable operation without modifying existing power-electronic equipment, using a programmable active filter that can be configured as an emulated impedance to mitigate ripple and transient disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a very large capacitor is used to provide energy buffering between AC power source and DC loads, then voltage ripple is reduced, but system cost and size increase significantly
Solution Approach 1:
The invention segments the capacitor function into two parts: a small physical capacitor and a virtual capacitor implemented through control algorithms. The small capacitor provides basic energy buffering while the virtual capacitor, created by modulating power flow from the AC source, provides additional effective capacitance without physical size, thereby reducing overall system size and cost while maintaining voltage stability.
Solution Approach 2:
The invention replaces part of the physical capacitor with a control-based virtual capacitor system. By using power electronic conversion and control algorithms to simulate capacitive behavior, the system achieves the same voltage stabilization effect without requiring a proportionally large physical capacitor, thus reducing system size and cost.
2Stability of the object's composition
If conventional ripple mitigation solutions are implemented, then voltage ripple is reduced, but modifications to existing hardware are required
Solution Approach 1:
The invention makes the power electronic converter serve multiple functions: it performs its primary power conversion function while simultaneously providing ripple mitigation through virtual capacitance. This multi-functionality allows the existing hardware to address both power conversion and voltage stabilization needs without requiring additional dedicated ripple mitigation components or modifications.
Solution Approach 2:
The system uses its own power electronic converter to provide ripple mitigation rather than requiring external dedicated equipment. The converter controls its own switching to create virtual capacitance that stabilizes the DC voltage, making the system self-sufficient for both power conversion and voltage regulation without external modifications.
3Stability of the object's composition
If conventional ripple mitigation solutions are implemented, then voltage ripple is reduced, but power factor and harmonics distortion are compromised
Solution Approach 1:
The invention uses dynamic control of the power electronic converter switching to achieve both ripple mitigation and maintain power quality. By dynamically adjusting switching patterns and using controlled rectification/inversion, the system can create virtual capacitance for voltage stabilization while simultaneously controlling input current waveform to maintain high power factor and low harmonics distortion.
Solution Approach 2:
The invention changes the operating parameters and control mode of the power electronic converter to achieve multiple objectives. By operating the converter in specific modes with optimized switching patterns and control algorithms, the system can provide virtual capacitance for ripple reduction while maintaining optimal power factor and minimizing harmonics distortion through parameter optimization.
Data Source
AI summary
In many power electronics systems, there is an intermediate DC-link stage for facilitating the power processing of different sources to their loads. A device called a plug-and-play ripple pacifier (RP) directly plugged into the DC-link, and actively removes undesired DC-link ripple, thereby eliminating the reliance on electrolytes capacitors for stabilizing the system and remove ripple. Importantly, the use of this device is non-invasive to the operation of its host systems, and requires no modification of existing hardware. It is suitable for the protection of DC utilities/systems and can also be used as a direct replacement of ripple-canceling E-Caps in power converters device.