Inverter Switching Control for Zero-Voltage Loss Reduction

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Solution Overview

Problem

Inverters experience significant switching losses due to the operation of electronic switches under voltage conditions, which contribute substantially to power dissipation and inefficiency.

Innovation Solution

The method involves controlling the switching of an inverter by disconnecting the power supply and connecting the terminals of the electronic switches and recirculation diodes to nullify the voltage on the transformer secondary, allowing switches to operate at zero voltage, and using a capacitor to charge and discharge energy efficiently, thereby minimizing switching losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electronic switches are operated under voltage conditions to control the inverter, then the switching control is simple and direct, but switching losses increase significantly due to power dissipation

Engineering Contradiction:
Improveswitching control simplicityVSAvoidswitching losses
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by disconnecting the power supply source from the transformer primary and reciprocally connecting the terminals through electronic switches and recirculation diodes before switching the chopper switches. This creates a zero-voltage condition at the transformer secondary, allowing the chopper switches to operate without voltage stress, thereby eliminating switching losses while maintaining simple control operation

Inventive Principle:
Principle #10Preliminary action

2Speed

If switches are switched under voltage conditions, then the switching response is fast, but power dissipation increases considerably

Engineering Contradiction:
Improveswitching response speedVSAvoidpower dissipation
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The method performs preliminary disconnection of the power supply and reciprocal connection of transformer terminals through switches and diodes before the chopper switching operation. This preparatory action establishes a zero-voltage state at the transformer secondary, enabling fast switching without voltage-induced power dissipation

Inventive Principle:
Principle #10Preliminary action

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

This approach significantly reduces switching losses by ensuring that all switches operate at zero voltage, enhancing circuit efficiency and reducing power dissipation compared to traditional hard switching methods.

Implementation Method 1

a bridge is adapted to chop a voltage from a direct voltage source for feeding a chopped voltage to a primary of a transformer... the voltage present on the secondary of said transformer is null

Methodology Applied
Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

a capacitor having a first terminal is connected to a first line from the rectifier and a second terminal is connected to a second line from the rectifier through a diode which allows the capacitor to be charged with the current from load M

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP2936669B1Method for driving inverters, and inverter adapted to reduce switching losses
Publication Date: 2017.06.07 HITACHI RAIL ITAL
  • EP2936669B1 patent drawingFigure 1
  • EP2936669B1 patent drawingFigure 2~3
  • EP2936669B1 patent drawingFigure 4~5

AI summary

A method for controlling the switching of an inverter (1), a bridge (2) of which is adapted to chop a voltage from a direct voltage source (4) for feeding a chopped voltage to a primary (L1) of a transformer (5); the inverter. (1) comprises a diode rectifier circuit (6) receiving the input voltage from the secondary (L2) of the transformer (5) in order to achieve a voltage fed to a chopper (7) which feeds a load (M). The method comprises : a step in which the switches of the bridge (2) are driven so that the power source (4) is disconnected from the primary (L1), the terminals of which are connected to each other by at least two of the electronic switches and recirculation diodes of the bridge itself, so that the voltage present on the secondary (L2) of said transformer is null; a step in which the switching of at least one electronic switch of a chopper branch is achieved when the voltage on the secondary is substantially null in order to minimize switching losses due to the opening/closing of the electronic -switch of the chopper.