Electronic Start-Winding Switching for Quiet Motor Control
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Solution Overview
Problem
Mechanical centrifugal switches used in electric motors for controlling start windings are prone to noise and manufacturing quality issues, limiting their effectiveness in applications like clothes dryers.
Innovation Solution
Implementing an electric motor system with electronically controlled switches, including a control unit, user interface, voltage sensor, current sensor, and heating component switches, to manage the operation of run and start windings, and heating components, eliminating the need for mechanical centrifugal switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mechanical centrifugal switch is used to control the start winding, then the device structure is simple and inexpensive, but noise is generated when the switch opens and closes and manufacturing quality issues occur
Solution Approach 1:
The patent replaces the mechanical centrifugal switch with an electronically controlled switch that uses electronic components (transistor, capacitor, resistor) instead of mechanical moving parts. This substitution eliminates the noise generated by mechanical contact opening and closing while maintaining the functionality of controlling the start winding energization and de-energization sequences.
2Ease of manufacture
If a mechanical centrifugal switch is used to control the start winding, then the device structure is simple and inexpensive, but manufacturing quality issues occur
Solution Approach 1:
The patent replaces the mechanical centrifugal switch with an electronically controlled switch that uses electronic components (transistor, capacitor, resistor) instead of mechanical moving parts. This substitution eliminates the noise generated by mechanical contact opening and closing while maintaining the functionality of controlling the start winding energization and de-energization sequences.
3Reliability
If an electronically controlled switch is used to control the start winding, then noise and manufacturing quality issues are reduced, but device complexity increases
Solution Approach 1:
The patent introduces a timing capacitor as an intermediary element that automatically controls the switching sequence. The capacitor charges when the start winding is energized and discharges to trigger the de-energization after a predetermined time delay. This intermediary mechanism eliminates the need for complex electronic control circuits while achieving reliable automated switching control.
Data Source
AI summary
A system in which the operation of an electric motor is controlled by electronically controlled switches. The system includes the motor having a run winding and a start winding, a heating component, and a motor control subsystem. A control unit closes a first switch to energize the run winding, closes a second switch to energize the start winding, determines based on an amplitude and a lag time of a current flowing through the motor whether the motor has started and is running normally, and if so, opens the second switch to de-energize the start winding and closes a third switch to activate the heating component. The control unit determines whether the motor has started and is running normally by comparing the real time amplitude and lag time of the current to a plurality of stored amplitudes and lag times associated with different operating conditions.