Electronically controlled switch for an electric motor
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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, affecting the operation of heavy load-driven devices like clothes dryers.
Innovation Solution
An electric motor system controlled by electronically controlled switches, including a control unit, user interface, voltage sensor, current sensor, and heating component switches, which manage the operation of run and start windings and heating components, replacing conventional mechanical centrifugal switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical centrifugal switches are used to control start winding de-energizing, then the device structure is simple and manufacturing cost is low, but noise is generated during switching and manufacturing quality issues occur
Solution Approach 1:
The patent replaces the mechanical centrifugal switch with an electronic control system comprising electronic switches (MOSFETs or IGBTs), microcontroller, and sensing circuits. This substitution eliminates mechanical contact noise while achieving reliable control of start winding de-energizing based on motor speed feedback from Hall effect sensors or back-EMF detection.
2Ease of manufacture
If mechanical centrifugal switches are used to control start winding de-energizing, then the device structure is simple and manufacturing cost is low, but manufacturing quality issues occur
Solution Approach 1:
The patent replaces mechanical centrifugal switches with an electronic control system comprising electronic switches (MOSFETs or IGBTs), microcontroller, and sensing circuits. This substitution eliminates mechanical contact noise while achieving reliable control of start winding de-energizing based on motor speed feedback from Hall effect sensors or back-EMF detection.
3Object-generated harmful factors
If electronically controlled switches are used to replace mechanical centrifugal switches, then noise is eliminated and manufacturing quality improves, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical centrifugal switch with an electronic control system comprising electronic switches (MOSFETs or IGBTs), microcontroller, and sensing circuits. This substitution eliminates mechanical contact noise while achieving reliable control of start winding de-energizing based on motor speed feedback from Hall effect sensors or back-EMF detection.
4Manufacturing precision
If electronically controlled switches are used to replace mechanical centrifugal switches, then manufacturing quality issues are reduced, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical centrifugal switch with an electronic control system comprising electronic switches (MOSFETs or IGBTs), microcontroller, and sensing circuits. This substitution eliminates mechanical contact noise while achieving reliable control of start winding de-energizing based on motor speed feedback from Hall effect sensors or back-EMF detection.
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 solution eliminates noise and manufacturing quality issues associated with mechanical switches, ensuring reliable and efficient control of electric motor operations, including start-up and normal running conditions, while activating heating components appropriately.
Implementation Method 1
a voltage sensor in electrical communication with the control unit and operable to sense a voltage being applied to the electric motor and to provide a first input signal to the control unit regarding the sensed voltage
Implementation Method 2
a current sensor in electrical communication with the control unit and electrically connected in series with the electric motor and operable to sense the electric current flowing through the electric motor and to provide a second input signal to the control unit regarding the sensed current
Implementation Method 3
an electric motor having a run winding and a start winding... a first electronically controlled switch electrically connected in series between the control unit and the run winding of the electric motor and operable to control flow of electric current to the run winding
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.