Active Filtering System for DC Bus Ripple Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing active filtering systems connected to a DC voltage source upstream are bulky, expensive, and generate high losses due to the need for large capacitors and high-voltage transistors, which are complex and inefficient.
Innovation Solution
An active filtering system connected between two power supply lines of a DC bus, utilizing a capacitor and a switching assembly with processing means to generate a compensation voltage, reducing the equivalent capacitance and minimizing losses by using low-voltage transistors and an inductor to absorb AC components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large chemical capacitors are used to absorb input voltage ripples, then filtering effectiveness is improved, but device volume and cost increase significantly
Solution Approach 1:
The patent replaces the mechanical/chemical capacitor system with an active filtering system using electronic components (transistors, inductors, and smaller capacitors) controlled by processing means. This substitution eliminates the need for large chemical capacitors while maintaining filtering effectiveness through active voltage compensation.
Solution Approach 2:
The invention changes the operating parameters by using low-voltage transistors (operating at a fraction of the DC bus voltage) instead of high-voltage transistors, and combines this with active control to achieve the same filtering effect with much smaller component values, particularly reducing capacitor size.
2Strength
If high-voltage transistors are used in series connection on the DC power supply bus, then voltage withstanding capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent fundamentally changes the voltage parameter by using low-voltage transistors that operate at a fraction of the DC bus voltage. The active filtering architecture allows these low-voltage transistors to effectively handle the high-voltage bus through controlled switching and voltage compensation, eliminating the need for complex high-voltage transistor designs.
Solution Approach 2:
The invention introduces an intermediary active filtering stage with low-voltage transistors and processing means that mediates between the high-voltage DC bus and the filtering function. This intermediary system converts the high-voltage problem into a low-voltage control problem, simplifying the transistor requirements.
3Reliability
If active filtering system is connected directly in series on the DC power supply bus, then filtering function is achieved, but power losses and component cost increase
Solution Approach 1:
The patent changes the current parameter by designing the system so that low-voltage transistors carry only the filtering current rather than the full load current. This parameter change dramatically reduces I²R losses in the active filtering components while maintaining effective voltage ripple compensation.
Solution Approach 2:
The invention segments the current paths by creating a separate active filtering branch that handles only the ripple current, while the main load current flows through the DC bus. This segmentation allows the filtering components to be dimensioned for much lower current, reducing power losses.
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 system achieves a compact, cost-effective design with reduced losses, improved filtering efficiency, and reliable operation by optimizing the equivalent capacitance and transistor design.
Implementation Method 1
a switching assembly controlled by processing means for generating a compensation voltage, opposite to the AC component of the voltage at the terminals of the first capacitor
Implementation Method 2
an inductor connected to the first terminal thereof and to a connection midpoint located between the two transistors
Data Source
AI summary
An active filtering system arranged for being connected between a first power supply line and a second power supply line of a DC bus, the bus being arranged for being connected to a DC voltage source located upstream, the system including a first capacitor arranged for being connected both to the first power supply line of the bus and to the second power supply line of the bus and to the terminals whereof a voltage is applied including an AC component, a switching assembly controlled by a processor for generating a compensation voltage, opposite to the AC component of the voltage at the terminals of the first capacitor, and including a first terminal connected to the first capacitor and a second terminal intended to be connected to the second power supply line.