DC-DC Converter Damping Control for Electrical Vibration Suppression
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Solution Overview
Problem
Existing power conversion systems in railway vehicles face challenges in stabilizing DC voltage due to voltage fluctuations from overhead wires, leading to electrical vibrations and inadequate control responses, with previous methods either delaying energy transmission or consuming resonance energy inefficiently.
Innovation Solution
A power conversion equipment with a first and second LC filter, a subtractor to detect DC power supply voltage, and a high-pass filter to generate a damping control quantity that suppresses electrical vibrations by adding it to the DC-DC converter's voltage command, improving control response and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If damping control is performed using filter capacitor voltage as control unit, then electrical vibration of LC filter is suppressed, but control response is delayed due to energy transmission delay according to LC filter circuit constants
Solution Approach 1:
The patent applies preliminary action by using filter reactor current as the control unit instead of filter capacitor voltage. The control system calculates the damping control quantity based on the filter reactor current and overhead wire voltage, which allows the control to act before the voltage fluctuation fully develops across the capacitor, thereby reducing control delay while maintaining vibration suppression effectiveness
Solution Approach 2:
The patent implements feedback by continuously monitoring the filter reactor current and overhead wire voltage, calculating the damping control quantity based on these real-time measurements, and applying it to the DC-DC converter. This closed-loop feedback mechanism ensures rapid response to voltage fluctuations while maintaining system stability
2Reliability
If resistor is connected in series with filter reactor to consume resonance energy, then resonance of LC filter is suppressed, but temperature rise and heat radiation of resistor occurs with deterioration of energy efficiency
Solution Approach 1:
The patent uses feedback control to suppress resonance by calculating a damping control quantity based on filter reactor current and overhead wire voltage, then applying this control to the DC-DC converter. This active control method suppresses resonance without dissipating energy through resistors, thereby maintaining energy efficiency while achieving resonance suppression
Solution Approach 2:
The patent replaces the passive mechanical damping approach (using resistors to consume resonance energy) with an active electronic control system. The DC-DC converter's switching control, modulated by the damping control quantity, actively counteracts resonance effects without the energy losses inherent in resistive damping
Data Source
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AI summary
The present invention aims at solving the prior art problem of not being able to suppress electrical vibration effectively due to insufficient control response against input voltage fluctuation in a damping control for suppressing electrical vibration that occurs to an input-side LC filter of a DC-DC converter. The power conversion equipment according to the present invention comprises, as a controller of a DC-DC converter, a subtractor for detecting a first filter capacitor voltage and a DC power supply voltage and subtracting the DC power supply voltage from the filter capacitor voltage, and a high-pass filter for cutting off a DC component from the result of calculation of the subtractor and shifting the phase of an AC component to output a damping control quantity, wherein the damping control quantity is added to a voltage command of the DC-DC converter to suppress the electrical vibration that occurs to an input-side LC filter of the DC-DC converter.