Motor Control Device for Compressor Driver Circuit Temperature Management

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Solution Overview

Problem

In electric compressors, the delay in temperature detection by temperature sensors leads to delayed changes in motor rotational speed or acceleration, resulting in inadequate heat suppression in the driver circuit unit, which can cause the temperature to exceed allowable limits or be suppressed more than necessary, reducing the output of the compression mechanism.

Innovation Solution

A motor-driven compressor with a temperature detection unit and a motor control device that stores a predetermined drive pattern based on the heat generation and cooling characteristics of the driver circuit unit, allowing for initial limit drive control to maintain the temperature within safe limits without repetitive temperature acquisition, transitioning to normal drive control once the temperature is stabilized.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If temperature detection is performed through insulating material, then the switching device is protected electrically, but the temperature detection is delayed

Engineering Contradiction:

Improveelectrical insulation protectionVSAvoidtemperature detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces a thermal conduction member as an intermediary between the switching device and temperature sensor. This mediator has high thermal conductivity to rapidly transmit temperature changes while maintaining electrical insulation, thus resolving the contradiction between protection and detection accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The temperature sensor is pre-positioned in close proximity to the switching device through the insulating member, preparing the detection system to immediately capture temperature changes once the thermal barrier is overcome by the thermal conduction member.

Inventive Principle:

Principle #10Preliminary action

2Temperature

If the motor rotational speed is reduced based on delayed temperature detection, then the driver circuit unit temperature is suppressed, but the compression mechanism output is reduced

Engineering Contradiction:

Improvedriver circuit unit temperatureVSAvoidcompression mechanism output

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The system performs preliminary temperature assessment at motor startup and proactively adjusts the drive pattern before excessive heat buildup occurs. By detecting temperature trends early and preemptively modifying motor operation, the system prevents overheating without unnecessarily reducing output.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The motor drive pattern is made dynamic and adaptable based on real-time temperature conditions. The control device adjusts rotational speed, acceleration rate, and other drive parameters dynamically according to the detected temperature, optimizing the balance between cooling and productivity.

Inventive Principle:

Principle #15Dynamics

3Temperature

If repetitive temperature detection and motor speed adjustment is performed, then the driver circuit unit temperature is controlled, but the control complexity increases

Engineering Contradiction:

Improvedriver circuit unit temperature controlVSAvoidcontrol system complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The system performs temperature assessment and drive pattern selection at motor startup as a preliminary action. This initial configuration establishes an appropriate drive pattern that anticipates temperature issues, reducing the need for continuous complex adjustments during operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system monitors temperature and adjusts key motor parameters such as rotational speed and acceleration rate. By focusing on these critical parameters rather than complex multi-variable control, the system achieves effective temperature management with manageable complexity.

Inventive Principle:

Principle #35Parameter changes

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 solution ensures the driver circuit unit is maintained at or below the allowable upper temperature limit, preventing unnecessary output reduction of the compression mechanism by limiting power supply to the motor based on initial temperature conditions, thus optimizing performance and efficiency.

Implementation Method 1

a driver circuit unit disposed at a position to be cooled by refrigerant drawn by the compression mechanism

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS10273958B2Compressor driven by a motor based on a temperature of a drive circuit

Publication Date: 2019.04.30 DENSO CORP

AI summary

A motor-driven compressor includes: a compression mechanism; an electric motor that drives the compression mechanism; a driver circuit unit disposed at a position to be cooled by refrigerant drawn by the compression mechanism; a temperature detection unit that detects a temperature of the driver circuit unit; and a motor control device disposed in the driver circuit unit to control the motor. The motor control device stores a predetermined drive pattern corresponding to a temperature characteristic of the driver circuit unit after starting the motor. When the temperature detected by the temperature detection unit at a time of starting the motor is higher than or equal to a predetermined temperature, the motor control device performs a limit drive control according to the predetermined drive pattern regardless of a drive state command to the motor.