Method for controlling a fan, a system, and an air conditioner

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Solution Overview

Problem

Variable frequency air conditioners experience abnormal shutdowns due to excessively high or low bus voltage, which is not effectively addressed by existing solutions that either increase costs and reduce reliability or limit air volume performance.

Innovation Solution

A method and system for controlling a fan by determining its initial state through electrical signals and applying matching control signals, involving the use of bridge arm groups and capacitor banks to manage bus voltage and rotation speed through closed-loop controls, preventing abnormal voltage fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If an uncontrollable rectifier is used in the variable frequency driver, then the device complexity is reduced, but the bus voltage becomes unstable and abnormal shutdowns occur

Engineering Contradiction:

Improvedriver complexityVSAvoidfan operation reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the control parameters of the inverter by detecting the electrical signals of the stator and determining the initial state (downwind forward, static start, or upwind reverse). Based on the detected initial state, the controller adjusts the driving signals to different bridge arm groups, thereby stabilizing the bus voltage and preventing abnormal shutdowns while maintaining relatively simple device complexity.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If upwind reverse start is used, then the fan can start against wind direction, but the bus voltage rises excessively causing abnormality

Engineering Contradiction:

Improvefan start adaptabilityVSAvoidbus voltage excessive rise

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of excessive bus voltage rise during upwind reverse start into a beneficial control opportunity. By detecting the initial state through stator electrical signals and identifying upwind reverse conditions, the controller applies specific control signals to manage the energy feedback, preventing voltage excessive rise while maintaining the adaptability to start against wind direction.

Inventive Principle:

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

3Reliability

If downwind forward start or static start is used, then the fan operates normally, but the bus voltage decreases excessively under low-voltage input conditions

Engineering Contradiction:

Improvefan operation reliabilityVSAvoidbus voltage excessive decrease

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism by continuously detecting the electrical signals of the stator and monitoring the bus voltage levels. When downwind forward start or static start is detected, the controller adjusts the driving signals based on the detected initial state and real-time voltage conditions, preventing excessive voltage decrease and maintaining stable operation under varying input voltage conditions.

Inventive Principle:

Principle #23Feedback

4Device complexity

If the fan initial state is not accurately determined, then the control system is simpler, but the control precision and fault reduction are insufficient

Engineering Contradiction:

Improvecontrol system complexityVSAvoidfan initial state detection precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces complex mechanical state detection methods with electrical signal detection. By measuring the electrical signals of the stator and analyzing their characteristics, the system accurately determines the fan's initial state (downwind forward, static start, or upwind reverse) without adding significant mechanical complexity, thereby achieving high measurement precision with minimal increase in system 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

This approach reduces abnormal faults in bus voltage and enhances overall air conditioner performance by accurately controlling fan states and maintaining stable operation across varying conditions.

Implementation Method 1

an inverter of the fan... applying a preset driving signal to a second bridge arm group in the inverter

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11374511B2Method for controlling a fan, a system, and an air conditioner

Publication Date: 2022.06.28 GREE ELECTRIC APPLIANCES WUHAN

AI summary

Embodiments of the present disclosure provide a method for controlling a fan, a system, and an air conditioner. The method includes: turning off a first bridge arm group in an inverter of the fan; applying a preset driving signal to a second bridge arm group in the inverter; detecting an electrical signal of a stator of the fan after the preset driving signal is applied; determining an initial state of the fan according to the electrical signal of the stator of the fan, wherein the initial state of the fan includes a downwind forward state, a static start state, or an unwind reverse state; and providing the fan with a control signal matching the initial state of the fan according to the initial state of the fan.