Synchronous Fluid Machine Rotation Control Without Position Sensors
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Solution Overview
Problem
Existing methods for controlling the direction of rotation of synchronous electric motors in fluid machines, particularly in household appliances, often require the use of position sensors, which increase production costs and can lead to incorrect start directions, resulting in degraded hydraulic performance and increased noise.
Innovation Solution
A method that involves starting a synchronous electric motor and applying phase cutting at a reference power level between the powers required for correct and incorrect directions of rotation, allowing for verification of the actual direction of rotation and ensuring correct starting without the need for position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a position sensor is used to control the direction of rotation, then the direction control reliability is improved, but the production cost increases
Solution Approach 1:
The invention extracts the position sensor from the system by implementing a sensorless control method. The control unit determines the starting position of the synchronous motor through electrical signals and control algorithms rather than physical sensors, thereby eliminating the sensor component while maintaining direction control capability
Solution Approach 2:
The invention replaces the mechanical position sensor with an electrical control system. The control unit uses electrical signals, current detection, and control algorithms to determine rotor position and control starting direction, substituting mechanical sensing with electrical field-based detection
2Ease of manufacture
If no position sensor is used to reduce cost, then the production cost decreases, but the direction control reliability deteriorates
Solution Approach 1:
The invention implements feedback control by having the control unit continuously monitor the motor's electrical parameters (current, voltage, phase) and adjust the starting signals accordingly. This closed-loop approach ensures accurate direction control without requiring physical position sensors
Solution Approach 2:
The synchronous motor system performs self-position-detection through its own electrical characteristics. The control unit exploits the motor's back-EMF, current consumption patterns, and phase relationships to automatically determine rotor position and control starting direction, making the system self-sufficient without external sensors
3Ease of manufacture
If the motor starts in the wrong direction, then the production cost is reduced (no sensor needed), but the hydraulic performance deteriorates and noise increases
Solution Approach 1:
The invention performs preliminary action by determining the correct starting position and direction before the motor actually starts rotating. The control unit calculates the appropriate starting phase and direction based on electrical parameters, ensuring the motor begins rotation in the correct direction from the outset, thereby preventing hydraulic performance degradation and noise issues
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 method effectively reduces the number of incorrect starts, maintains hydraulic performance, and avoids the additional costs associated with position sensors, while also allowing for sensorless operation.
Implementation Method 1
a synchronous electric motor which operates said fluid machine
Implementation Method 2
an oriented impeller, driven by means of a synchronous electric motor
Data Source
AI summary
A method for controlling the direction of rotation of a fluid machine having an oriented-blade impeller, comprising the following steps:starting (100) a synchronous electric motor which operates said fluid machine until the synchronous state is reached;driving (200) said synchronous electric motor at steady state by applying a phase cutting;applying (300) a phase cutting corresponding to a reference power, wherein said reference power is comprised between a first power required to keep the propeller rotating in a right direction and a second power required to keep the propeller rotating in a wrong direction, which is opposed to the right direction.