Speed Regulator Supercapacitor THDI Reduction
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Solution Overview
Problem
Existing variable speed drives do not effectively reduce Total Harmonic Distortion Index (THDI) at the input of the rectifier module, which affects the efficiency and compatibility with electrical supply networks.
Innovation Solution
Incorporating a DC/DC converter connected in parallel with the bus capacitor, a first inductor to transform the voltage source into a current source, and a second inductor connected in series with the first inductor, along with a control module to manage the current flow through energy storage means, such as supercapacitors, to control the DC/DC converter and reduce THDI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC/DC converter is connected in parallel with the bus capacitor to store braking energy and supply power during starting, then the device can fulfill energy storage and power supply functions, but the THDI at the input of the rectifier module is not reduced
Solution Approach 1:
A current source is introduced as an intermediary between the voltage source (bus capacitor) and the DC/DC converter. This current source, implemented through a device that transforms the voltage source into a current source, acts as a mediator that filters the current waveform, thereby reducing THDI while maintaining the energy storage and power supply functions of the DC/DC converter system
Solution Approach 2:
The system is segmented into distinct functional modules: the bus capacitor (voltage source), the current source transformation device, and the DC/DC converter. This segmentation allows each component to perform its specific function optimally - the voltage source provides energy storage, the transformation device handles current waveform conditioning, and the converter manages power conversion, thereby reducing overall THDI
2Object-generated harmful factors
If a device is added to transform the voltage source into a current source, then THDI is reduced, but the device complexity increases
Solution Approach 1:
The current source transformation device is designed to serve multiple functions: it transforms the voltage source into a current source, filters current harmonics to reduce THDI, and interfaces with the DC/DC converter system. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving THDI reduction
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 significantly reduces THDI at the input of the variable speed drive, optimizing the dimensioning of electronic switches and enhancing the drive's compatibility with single- or three-phase supply networks, while maintaining energy storage and power supply functions.
Implementation Method 1
a first inductor (L1), making it possible to transform the voltage source constituted by the bus capacitor (Cb) into a current source
Implementation Method 2
a second inductor (L2) connected in series with the first inductor
Implementation Method 3
means for storing the electrical energy recovered during braking of the electrical load, such as one or more supercapacitors
Data Source
Figure 1
AI summary
The regulator (1) has an inductor (L2) mounted on a positive line or negative line of a continuous power supply bus between a direct current/direct current converter (14) and a bus capacitor (Cb). The capacitor is connected between the lines of the bus. The inductor transforms a voltage source formed by the capacitor into a current source. An estimating unit estimates currents (I1, I2) circulating in the lines of the bus. A converter control module (2) controls current (luc) passing through a supercapacitor (UC), based on the estimated currents.