Compressor Winding Short Circuit for Rapid Rotor Braking

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Solution Overview

Problem

Inverter air conditioners face challenges in achieving closed-loop control at low speeds due to the inability to measure rotor rotation speed, leading to direct compressor shutdown or frequency reduction, which results in piping vibrations and stress during shutdown.

Innovation Solution

A method and device that control the compressor by shorting three-phase windings of the compressor using a drive circuit and controller, generating a brake torque to rapidly stop the rotor, thereby reducing vibrations and stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the compressor is stopped directly by stopping the drive signal, then the shutdown process is simple, but the compressor stops in a manner of oscillation attenuation causing piping vibration and stress

Engineering Contradiction:

Improveshutdown process simplicityVSAvoidpiping vibration and stress

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by introducing a brake torque through short-circuiting the windings before the compressor naturally stops. This brake torque acts in opposition to the rotation direction to preemptively counteract the oscillation attenuation that would otherwise cause harmful vibrations and stress in the piping system.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent converts the harmful oscillation attenuation into a beneficial controlled stopping process. By utilizing the short-circuit braking effect, the natural oscillation that causes vibration is transformed into a controlled deceleration with brake torque, eliminating the harmful vibrations while maintaining the simplicity of direct shutdown.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Stability of the object's composition

If the frequency is reduced to a low frequency to stop the compressor, then the shutdown process is smoother, but the frequency cannot be reduced to zero and the stopping process is prolonged

Engineering Contradiction:

Improveshutdown smoothnessVSAvoidstopping time

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

The patent applies dynamics by transitioning from a static frequency reduction approach to a dynamic braking approach. Instead of gradually reducing frequency to zero, the system dynamically applies brake torque through winding short-circuiting, enabling the compressor to stop quickly while maintaining shutdown smoothness through controlled deceleration.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If no speed measurement is used to control the compressor, then the control system is simpler, but closed-loop control at low speed cannot be achieved

Engineering Contradiction:

Improvecontrol system complexityVSAvoidlow speed control reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the mechanical speed measurement system with an electrical braking control system. Instead of using mechanical sensors and closed-loop control circuits, the system uses electrical short-circuiting of the windings to generate brake torque, achieving reliable low-speed stopping without adding mechanical measurement complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables the compressor to stop and stay still rapidly, reducing piping vibrations and stress, and prolonging the working life of air conditioner pipes.

Implementation Method 1

controlling a drive circuit of the compressor to short three phase windings of the compressor... generating a brake torque generated by shorting the three phase windings

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10411618B2Air conditioner, and method and device for controlling its compressor to stop

Publication Date: 2019.09.10 GD MIDEA AIR CONDITIONING EQUIP CO LTD

AI summary

An air conditioner, a method and a device for controlling a compressor in the same are disclosed in the present disclosure. The method includes: during a shutdown process of the air conditioner, controlling a drive circuit of the compressor to short three phase windings of the compressor if receiving a stop signal for stopping the compressor; and controlling a rotor of the compressor to stop according to a brake torque generated by shorting the three phase windings, to stop the compressor. The method shorts the three phase windings by controlling the drive circuit, thus to generate the brake torque to control the rotor to stop faster. As a result, the method enables the compressor to stop and to stay still rapidly, thereby facilitating to reduce a piping stress in the air conditioner and to prolong a working life of a pipe in the air conditioner.