Power Converter Bridge Control for Balanced Arm Heat Generation

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Solution Overview

Problem

Existing power converting apparatuses experience uneven heat generation between arms due to differing switching frequencies, leading to potential operational failures if heat dissipation measures are not implemented, limiting high output capabilities.

Innovation Solution

The power converting apparatus employs a bridge circuit with switching elements made of wide bandgap semiconductors and a control unit that generates drive pulses to manage switching operations, ensuring that switching elements in the first arm and second arm operate complementarily to reduce heat generation unevenness and prevent capacitor short circuits, thereby maintaining efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If switching elements in the first arm operate at higher switching frequencies to control power supply current, then power supply current control is improved, but heat generation becomes uneven between arms causing operational failures

Engineering Contradiction:
Improvepower supply current controlVSAvoidheat generation uniformity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the switching frequency parameter of the second arm to match the first arm's switching frequency. This parameter adjustment ensures that both arms generate heat at comparable rates, resolving the uneven heat generation problem while maintaining effective power supply current control through the first arm's higher frequency operation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates equipotentiality in terms of switching frequency between the two arms. By making the switching frequencies equal, the system achieves balanced operational conditions where both arms experience similar stress and heat generation, preventing the reliability issues caused by excessive temperature differences

Inventive Principle:
Principle #12Equipotentiality

2Reliability

If heat dissipation measures are implemented to enable continuous operation of the first arm, then operational reliability is improved, but device complexity and cost increase

Engineering Contradiction:
Improvecontinuous operation capabilityVSAvoidheat dissipation system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by having the second arm's switching elements operate at the same frequency as the first arm, automatically balancing heat generation across both arms. This self-regulating approach eliminates the need for external heat dissipation measures while ensuring continuous operation capability, thereby reducing device complexity

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3664271B1Power conversion device, motor drive device, and air conditioner
Publication Date: 2024.02.14 MITSUBISHI ELECTRIC CORP
  • EP3664271B1 patent drawingFigure 1~2
  • EP3664271B1 patent drawingFigure 3~4
  • EP3664271B1 patent drawingFigure 5~6

AI summary

A power converting apparatus includes: a first arm (31) including a switching element (311) and a switching element (312) connected in series; a second arm (32) including a switching element (321) and a switching element (322) connected in series, the second arm (32) being connected in parallel with the first arm (31); a reactor (2) having one end connected to the switching element (311) and the switching element (312) and an opposite end connected to an alternating-current power supply 1; and a smoothing capacitor (4) connected in parallel with the first arm (31) and the second arm (32). The loss characteristic of the switching element (311) and the second switching element (312) that occurs in each switching event is better than the loss characteristic of the switching element (321) and the switching element (322) that occurs in each switching event.