Regenerative Inverter Control Apparatus for DC-Link Ripple Reduction

Solution Overview

Problem

Existing medium voltage inverter systems experience significant ripple in DC-link power voltage, leading to increased capacitance requirements, which in turn increases system volume and cost, while reducing reliability.

Innovation Solution

A control apparatus for regenerative medium voltage inverters that includes a power compensation voltage generating unit to actively control the switching of converter units, reducing the ripple in DC-link power voltage by compensating for power differences between input and output, thereby minimizing the capacitance of the DC-link capacitor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the capacitance of the DC-link capacitor is increased to reduce ripple in DC-link power voltage, then the ripple is reduced, but the system volume and cost increase

Engineering Contradiction:

Improveripple in DC-link power voltageVSAvoidsystem volume

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The patent replaces the passive mechanical approach of using large capacitance to suppress ripple with an active control system. The power compensation voltage generating unit actively generates compensating voltages to cancel out power imbalances, substituting the need for large physical capacitors with electronic control mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameters of the converter units by generating power compensation voltages that actively adjust the switching behavior. This dynamic parameter adjustment allows the system to maintain stable DC-link voltage without requiring excessive capacitance, thereby reducing system volume while effectively suppressing ripple.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the capacitance of the DC-link capacitor is increased to reduce ripple in DC-link power voltage, then the ripple is reduced, but the cost increases

Engineering Contradiction:

Improveripple in DC-link power voltageVSAvoidsystem cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent replaces the passive mechanical approach of using large capacitance to suppress ripple with an active control system. The power compensation voltage generating unit actively generates compensating voltages to cancel out power imbalances, substituting the need for large physical capacitors with electronic control mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameters of the converter units by generating power compensation voltages that actively adjust the switching behavior. This dynamic parameter adjustment allows the system to maintain stable DC-link voltage without requiring excessive capacitance, thereby reducing system volume while effectively suppressing ripple.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If the capacitance of the DC-link capacitor is increased to reduce ripple in DC-link power voltage, then the ripple is reduced, but the reliability decreases

Engineering Contradiction:

Improveripple in DC-link power voltageVSAvoidsystem reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent replaces the passive mechanical approach of using large capacitance to suppress ripple with an active control system. The power compensation voltage generating unit actively generates compensating voltages to cancel out power imbalances, substituting the need for large physical capacitors with electronic control mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control mechanism where the power compensation voltage generating unit continuously monitors power imbalances and adjusts the converter switching in real-time. This active feedback control effectively suppresses ripple and improves system reliability by preventing voltage instability, replacing the passive reliability approach of over-engineering with large capacitors.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9054600B2Control apparatus for regenerative medium voltage inverter

Publication Date: 2015.06.09 LSIS CO LTD

AI summary

A control apparatus for regenerative medium voltage inverter is disclosed. The control apparatus controls a switching of a PWM converter unit by generating a voltage compensating a power difference between an input and an output of the PWM converter unit.