Single-Phase Induction Motor Start Winding Phase Shift Control
Solution Overview
Problem
Existing single-phase induction motor starting devices, such as PTC, electromechanical relays, and temporizer-type components, face inefficiencies in optimizing start winding conduction time, leading to suboptimal starting performance and energy consumption across varying motor sizes, lacking adaptability and standardization.
Innovation Solution
A method and system that continuously monitor phase shifts between electrical quantities during motor startup, allowing for adaptive de-energization of the start winding at optimal moments by measuring and comparing first and second phase shift levels, enabling efficient startup regardless of motor size or supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If PTC device is used for starting, then the start winding conduction time is extended, but energy consumption increases and starting performance deteriorates for high-power motors
Solution Approach 1:
The patent employs feedback control by continuously monitoring the phase shift between main winding current and start winding current. The starting device adjusts the conduction time of the start winding based on real-time phase shift measurements, ensuring optimal starting performance and energy efficiency across different motor power ratings.
Solution Approach 2:
The starting device dynamically adapts the start winding conduction time based on motor characteristics and operating conditions. By using phase shift monitoring, the system automatically adjusts the starting parameters to match the specific motor requirements, rather than using fixed timing for all motor sizes.
2Ease of operation
If electromechanical relay is used for starting, then starting control is achieved, but component standardization is lost and manufacturing complexity increases
Solution Approach 1:
The starting device is designed as a universal component that can control starting for various motor sizes and types. By using electronic phase shift monitoring instead of motor-specific mechanical relays, a single standardized device performs the starting control function across different applications, eliminating the need for custom dimensioning.
Solution Approach 2:
The patent replaces mechanical electromechanical relays with an electronic starting device that uses phase shift detection and electronic switching. This substitution eliminates mechanical wear, improves reliability, and enables standardized components to replace custom-mechanical solutions.
3Loss of time
If temporizer-type starting components are used, then starting time control is provided, but adaptability to different motor sizes is lost and inventory requirements increase
Solution Approach 1:
The starting device uses continuous phase shift feedback to determine the optimal moment to disconnect the start winding. This feedback mechanism automatically adapts to different motor sizes, loads, and operating conditions, eliminating the need for pre-set timing values for different motor families.
Solution Approach 2:
The system dynamically changes the starting parameters (conduction time, phase shift angle) based on real-time motor performance. By monitoring phase shift variations, the device automatically adjusts the starting process to match the specific characteristics of each motor, providing both time control and adaptability.
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 optimizes startup by ensuring the start winding is de-energized at the right moment, improving performance and reducing energy consumption across different motor sizes without the need for specific components, allowing for standardized and cost-effective implementation.
Implementation Method 1
monitoring a phase shift between electrical quantities of the single-phase induction motor along a first stage of stability; measuring a first level of the phase shift
Implementation Method 2
the main winding is energized by a source of alternating voltage, while the start winding is energized temporarily, thus creating a rotating magnetic field in the stator air gap, a condition that is necessary to accelerate the rotor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A device, system and method for starting a single-phase induction motor comprising the steps of: i) energizing the start winding (50b) and continuously estimating an operating rotation (R1) of the single-phase induction motor throughout its operation; ii) measuring a first phase shift level (D1) between at least two electrical quantities of the motor along a first stability stage (E1); iii) monitoring the variation of the first phase shift level (D1) according to the increase of the operating rotation (R1) of the motor along the first stability stage (E1); iv) detecting an inflection stage (Einf) from the first phase shift level (D1) to a second phase shift level (D2), when the operating rotation (R1) of the motor is close to a regime rotation (R2); v) measuring the second phase shift level (D2) between at least two electrical quantities of the motor along a first stability stage (E2); and vi) de-energizing the start winding (50b) when the operating rotation (R1) reaches the regime rotation (R2).