Motor Drive Voltage Control to Avoid Flux Weakening Losses

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Solution Overview

Problem

Motors designed for 200 V-class power supply regions experience increased losses when used in 400 V-class regions due to the need for flux weakening control, leading to higher motor and power converter losses.

Innovation Solution

The motor drive apparatus eliminates the need for flux weakening control by configuring the motor and power converter to operate efficiently under 400 V-class power supplies, reducing motor current and associated losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If flux weakening control is performed in a 400 V-class power supply region, then the motor can operate at higher voltages, but motor current increases leading to greater losses

Engineering Contradiction:

Improvepower supply voltage utilizationVSAvoidmotor loss and power converter loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent changes the control parameter from flux weakening control to a control method that limits voltage between windings. By controlling the voltage between windings to be below the partial discharge inception voltage, the system operates efficiently without flux weakening, reducing motor current and losses while still utilizing 400 V-class power supply

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the same motor is used in both 200 V-class and 400 V-class power supply regions, then versatility is improved, but losses increase in 400 V-class regions

Engineering Contradiction:

Improvemotor compatibility across voltage regionsVSAvoidmotor loss and power converter loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent enables the motor to be universally used in both 200 V-class and 400 V-class power supply regions by implementing a control method that adapts to different voltage inputs. The controller limits voltage between windings to prevent partial discharge, allowing the same motor design to operate efficiently across different voltage regions without incurring excessive losses

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If voltage between windings is increased to utilize 400 V power supply, then power output is improved, but partial discharge occurs in the motor

Engineering Contradiction:

Improvepower output capabilityVSAvoidpartial discharge in motor

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by proactively limiting the voltage between windings to be below the partial discharge inception voltage. This preventive measure stops partial discharge from occurring in the first place, allowing the system to safely utilize 400 V-class power supply without the harmful effects of partial discharge

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentEP3926817B1Motor drive apparatus and cooling apparatus

Publication Date: 2025.01.22 DAIKIN INDUSTRIES LTD

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AI summary

A power converter (10) and a controller (40) for controlling a voltage supplied to a motor by the power converter are provided. A d-axis inductance of the motor (30) is indicated by Ld. A flux linkage of the motor (30) is indicated by ϕ. A maximum output of the motor (30) in a device where the motor (30) is mounted is indicated by Pmax. The motor (30) is configured so that a value of ϕ × Vx/Ld is greater than Pmax when an effective value voltage Vx = 200 V The controller (40) has a control mode that applies an effective value voltage higher than the effective value voltage Vx to the motor (30).