PTC Starter Circuit for Motor Start-Up Power Reduction
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Solution Overview
Problem
Conventional PTC thermistor starters in motor circuits result in wasteful electric power consumption after motor start-up due to high resistance maintaining low current through secondary windings, affecting the lifespan of control PTCs and causing motor noise and fluctuations.
Innovation Solution
A PTC starter design with a control PTC thermistor and a start PTC thermistor connected in series, where the start PTC thermistor's heat increases the control PTC's resistance, reducing current flow through the TRIAC and secondary winding, minimizing power waste and extending the control PTC's lifespan by maintaining thermal communication with reduced volume and distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PTC thermistor is connected in series with the secondary winding to disconnect it after motor start, then the secondary winding is effectively taken out of service, but the PTC thermistor consumes about 3W power continuously due to high resistance and heated state
Solution Approach 1:
The patent extracts the power consumption problem by introducing a parallel PTC thermistor that provides an alternative current path. The control PTC thermistor is taken out from the main series circuit and placed in parallel, allowing current to bypass the power-consuming path while maintaining the disconnection function of the secondary winding.
Solution Approach 2:
The control PTC thermistor acts as an intermediary component that mediates between the main circuit and the secondary winding. It provides thermal coupling to sense the temperature rise of the start PTC thermistor and accordingly adjusts its resistance to control the current flow, thereby eliminating continuous power consumption while maintaining reliable disconnection.
2Reliability
If the control PTC thermistor volume is increased to avoid too short OFF time, then the motor can start reliably, but the device volume increases and the half wave cycle becomes too long causing motor noise and fluctuation
Solution Approach 1:
The patent applies local quality by using a small-volume control PTC thermistor that is thermally coupled to the start PTC thermistor. The local thermal field created by the start PTC thermistor provides the necessary temperature signal to the control PTC, eliminating the need for a large-volume control PTC that would otherwise be required to generate sufficient heat independently. This localized thermal interaction maintains reliable motor start while minimizing device volume and avoiding motor noise.
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
Substantially reduces power consumption and prolongs the life of control PTCs by efficiently managing current flow through the motor windings, minimizing noise and fluctuations, and optimizing the operation space.
Implementation Method 1
the start PTC thermistor's heat increases the control PTC's resistance
Implementation Method 2
a control PTC thermistor and a start PTC thermistor connected in series, where the start PTC thermistor's heat increases the control PTC's resistance
Implementation Method 3
maintaining thermal communication with reduced volume and distance
Data Source
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AI summary
Certain configurations of the present disclosure present a PTC starter. The PTC starter includes a housing, a first conductive terminal (6), a second conductive terminal (7), a control PTC thermistor (3), a start PTC thermistor (4) and a TRIAC (5), wherein the control PTC thermistor (3), the start PTC thermistor (4) and the TRIAC (5) being accommodated in the housing, the start PTC thermistor (4) being connected in series with the TRIAC (5), wherein one electrode of the control PTC thermistor (3) is connected with the gate (G) of the TRIAC (5), the control PTC thermistor (3) is connected in series with the start PTC thermistor (4), the volume of the control PTC thermistor (3) is less than 30mm3, and the distance between the control PTC thermistor (3) and the start PTC thermistor (4) is less than 5mm.