Method of operating a motor coupled to a mechanical load

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Solution Overview

Problem

Existing electric drive apparatuses for transport refrigeration systems face challenges in maintaining stable voltage on the DC bus due to fluctuations in the electrical power drawn by the motor as a result of varying mechanical loads.

Innovation Solution

A method of operating a motor coupled to a mechanical load, involving determining a fluctuating speed demand to reduce variations in total power drawn or provided by the motor, and controlling the motor based on a rotary component speed reference value derived from this demand.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the motor operates with varying mechanical load, then the motor can adapt to different operational requirements, but the voltage on the DC bus fluctuates undesirably

Engineering Contradiction:

Improveadaptability to mechanical load variationsVSAvoidvoltage stability on DC bus

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The controller preemptively adjusts the motor speed reference value based on detected load changes before significant power fluctuations occur. By calculating the fluctuating speed demand in advance and adjusting the speed reference, the system prevents rather than merely reacts to voltage instability on the DC bus.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the mechanical load on the motor and uses this feedback to dynamically adjust the speed reference value. The controller detects load variations and modifies the motor operating parameters in real-time to maintain stable DC bus voltage while adapting to changing operational requirements.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If large electrical energy storage devices are used to stabilize DC bus voltage, then voltage stability is improved, but the device complexity and cost increase

Engineering Contradiction:

Improvevoltage stability on DC busVSAvoidcomplexity of electric drive apparatus

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces the need for large physical energy storage devices with a control-based solution. Instead of using substantial capacitors or batteries to stabilize voltage, the system uses intelligent speed control of the motor to inherently reduce power fluctuations, thereby stabilizing the DC bus voltage through control algorithms rather than passive energy storage hardware.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system stabilizes DC bus voltage by dynamically changing the motor speed parameter. By adjusting the speed reference value based on load conditions, the motor's power consumption is modulated to reduce fluctuations on the DC bus, achieving voltage stability through parameter optimization rather than hardware augmentation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250052466A1Method of operating a motor coupled to a mechanical load

Publication Date: 2025.02.13 THERMO KING CORP

AI summary

The present disclosure relates to a method of operating a motor having a rotary component coupled to a mechanical load. The method includes determining a fluctuating speed demand corresponding to a temporally varying component of a speed of the rotary component. The method also includes determining a rotary component speed reference value based on the fluctuating speed demand. Also, the method includes controlling the motor in accordance with the rotary component speed reference value. The fluctuating speed demand is determined so as to reduce variations in a total power drawn or provided by the motor in use.