Bridge Converter Switching Control for Balanced Heat Generation

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Solution Overview

Problem

Existing diode bridge circuits experience imbalanced heat generation due to differences in switching element characteristics, leading to excessive heat in specific elements and limited output.

Innovation Solution

A converter device with a bridge circuit having arm portions with identical switching elements and a control unit that alternates the on-off cycles of these elements based on alternating voltage cycles to balance heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If different power transistors are adopted for the first and second switching elements and for the third and fourth switching elements to separate functions, then switching performance is improved, but heat generation becomes imbalanced and output is limited

Engineering Contradiction:
Improveswitching speedVSAvoidheat generation balance
Core Design Contradiction:
SpeedVSTemperature

Solution Approach 1:

The patent applies local quality by assigning different switching speeds to different arm portions based on their specific functional requirements. The first and second arm portions use high-speed switching elements for rapid response, while the third and fourth arm portions use low-speed switching elements with lower on-resistance for efficient power conduction, optimizing each location's characteristics for its specific role

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by dynamically switching between different arm portions for PAM control based on operational conditions. The control unit selectively activates either the first and second arm portions or the third and fourth arm portions depending on the required switching speed and heat generation considerations, allowing the system to adapt its characteristics in real-time

Inventive Principle:
Principle #15Dynamics

2Speed

If high-speed switching elements are used for the first and second switching elements, then switching performance is improved, but heat generation in these elements increases excessively

Engineering Contradiction:
Improveswitching speedVSAvoidswitching loss
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The patent uses dynamics by dynamically selecting which arm portions perform PAM control based on operational requirements. When high-speed switching is needed, the first and second arm portions are activated; when lower switching speed is acceptable and heat generation is a concern, the third and fourth arm portions are used instead, allowing the system to adapt its switching characteristics

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies periodic action by alternating between different arm portions for PAM control operations. The control unit periodically switches between using the high-speed first and second arm portions and the low-speed third and fourth arm portions, distributing the switching stress and heat generation over time and across different components

Inventive Principle:
Principle #19Periodic 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 suppresses excessive heat generation in specific switching elements, improves efficiency, and reduces the need for larger heat dissipating components.

Implementation Method 1

a bridge circuit that has a first arm portion including a plurality of switching elements and a second arm portion including a plurality of switching elements, and that rectifies alternating power supplied from an alternating power supply

Methodology Applied
Scientific EffectRectification:

Data Source

PatentEP4693874A1Converter device, air-conditioning device provided with converter device, and method for controlling converter device
Publication Date: 2026.02.11 MITSUBISHI HEAVY IND THERMAL SYST
  • EP4693874A1 patent drawingFigure 1
  • EP4693874A1 patent drawingFigure 2
  • EP4693874A1 patent drawingFigure 3

AI summary

The present invention provides a converter device that suppresses excessive heat generation in only a specific switching element. The converter device has a first arm unit (arm1) provided with a plurality of switching elements (Tr1, Tr3), and a second arm unit (arm2) provided with a plurality of switching elements (Tr2, Tr4). Said converter device comprises a bridge circuit (200) that rectifies alternating current power supplied from an alternating current source (4), and a control unit (24) that controls the switching on/off of the plurality of switching elements of the first arm unit and the plurality of switching elements of the second arm unit. At each prescribed cycle of the alternating current voltage supplied from the alternating current source, the control unit switches the switching elements within each arm unit on/off, the arm units having the same electrical characteristics.