Capacitor-Start Motor Auxiliary Winding Switching Circuit
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Solution Overview
Problem
Existing methods for energizing the auxiliary winding of capacitor-start single-phase induction motors, such as those using potential and current relays, face challenges with high complexity and cost due to design-dependent electrical parameters, leading to increased stock keeping units and voltage stress on switches.
Innovation Solution
A system comprising an electromechanical switch and an electronic switch connected in series with a start capacitor, where the electronic switch operates in parallel and simultaneously with the electromechanical switch for stabilization, reducing voltage levels and enabling smooth switching, controlled by a unit that manages overlapping operation periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potential relays or current relays are used to energize the auxiliary winding, then the motor can be started, but the electrical parameters become strongly dependent on motor design, increasing device complexity and SKU variety
Solution Approach 1:
The patent applies universality by using a standardized relay device that can control auxiliary winding energization across different motor designs. The relay is designed with universal electrical parameters that do not depend on specific motor characteristics, allowing the same relay type to be used in multiple motor applications, thereby reducing SKU variety and device complexity while maintaining reliable motor starting functionality.
Solution Approach 2:
The patent applies parameter changes by modifying the relay's electrical parameters to be independent of motor design variables. Specifically, the relay is designed with optimized coil resistance, contact ratings, and time characteristics that remain constant across different motor types, transforming the parameter dependency issue into a universal solution that simplifies the overall system.
2Reliability
If potential relays or current relays are used to energize the auxiliary winding, then the motor can be started, but stock keeping units and material handling costs increase
Solution Approach 1:
The patent reduces material handling complexity by implementing a universal relay design that can serve multiple motor models. This standardization allows for simplified inventory management, reduced SKU proliferation, and easier material handling in manufacturing and distribution, while maintaining the reliable motor starting function across different applications.
3Ease of operation
If bidirectional switches are used in the energizing system, then switching control is achieved, but voltage stress on the switches increases
Solution Approach 1:
The patent applies the intermediary principle by introducing a capacitor in parallel with the bidirectional switch. This capacitor acts as a mediator that absorbs voltage spikes and reduces voltage stress on the switch during operation. The capacitor provides a temporary energy storage mechanism that smooths out voltage fluctuations, allowing the switch to operate with reduced stress while maintaining effective switching control.
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 configuration reduces voltage stress on switches and simplifies switching operations, reducing the complexity and cost associated with material handling while ensuring stable motor operation.
Implementation Method 1
a start capacitor (14) and an electromechanical switch (12) connected in series with the auxiliary winding (11)
Implementation Method 2
an electromechanical switch (12) connected in series with the auxiliary winding (11), the electromechanical switch being used to energize the auxiliary winding (11)
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a system and a method for energizing an auxiliary winding of a capacitor-start single-phase induction motor. Said system and method aim at reducing the voltage level in the bidirectional switches present in the topology during the blocking of said switches. The system and method proposed also aim at providing smooth switching of the electromechanical bidirectional switch existing in the topology. These gains in the reduction of the voltage level in the bidirectional switches and the smooth switching of the electromechanical bidirectional switch are achieved by means of a system for energizing an auxiliary winding of an electric motor, the auxiliary winding (11 ) being connectable in series with a voltage network (VAC), the system comprising a start capacitor (14) and an electromechanical switch (12) connected in series with the auxiliary winding (11 ), the system comprising an electronic switch (13) connected in parallel with the series association of the electromechanical switch (12) and the start capacitor (14), the electronic switch (13) and the electromechanical switch (12) being used to turn on the auxiliary winding (11 ), the system being configured so that the electronic switch (13) can be turned on simultaneously with the electromechanical switch (12) and kept on simultaneously with the electromechanical switch (12) for a stabilization time (tb, td). A method for controlling the system of the present invention is also disclosed.