Single-Coil Contactor Circuit for Fast Polarity-Reversing Actuation
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Solution Overview
Problem
Existing contactors are limited in transitioning between states due to the need for two separate coils with opposite magnetic polarity, which restricts speed and requires additional space and higher coil current ratings without volumetric expansion.
Innovation Solution
A contactor design with a coil polarity reversing circuit that uses a single coil with switches to reverse polarity each actuation, allowing faster state transitions by utilizing the same coil for both power-up and trip inputs, and incorporating transient voltage suppression to manage back electromotive forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If two separate coils with opposite magnetic polarity are employed to initiate state transitions, then the contactor can transition between tripped and operational states, but the transition speed is limited and additional volumetric space is required
Solution Approach 1:
The patent merges the function of two separate coils into a single coil by implementing a polarity reversing circuit. The single coil is wound to provide magnetic polarity in one direction, and switches reverse the polarity of current flow through the coil depending on whether the contactor is in the tripped or operational state. This combining approach eliminates the need for two separate coils, reducing volumetric space while enabling faster state transitions.
Solution Approach 2:
The patent applies dynamics by making the coil polarity reversible through switching mechanisms. Instead of having fixed polarity coils, the system dynamically reverses the polarity of the single coil based on the current state of the contactor. This dynamic polarity reversal allows the same coil to provide force in both directions (closing and opening), increasing transition speed without requiring additional space for second coils.
2Speed
If coil size is increased to achieve faster state transitions, then transition speed improves, but volumetric space requirements increase
Solution Approach 1:
The patent combines the functionality of two coils into one, allowing the single coil to be optimized for size and speed. By reversing polarity rather than adding another coil, the system achieves fast transitions without proportionally increasing volume.
Solution Approach 2:
The patent changes the electrical parameter of current direction (polarity) rather than changing the physical size of the coil. By controlling the direction of current flow through the single coil, the system achieves bidirectional actuation with a coil of fixed, optimized dimensions.
3Speed
If higher coil current rating is required for faster transitions, then state transition speed improves, but additional volumetric space is needed
Solution Approach 1:
The patent merges high-current capability into a single coil design with polarity reversal. The single coil is designed to handle higher current ratings, and the polarity switching mechanism allows this single high-current coil to replace what would traditionally require two separate coils, thus achieving high-speed transitions without proportional volume increase.
4Speed
If a single coil is used with polarity reversal, then volumetric space is reduced and transition speed increases, but voltage transients and back electromotive forces are generated
Solution Approach 1:
The patent converts the harmful back electromotive force generated by the single coil into a beneficial holding mechanism. The back EMF generated when the coil is de-energized is directed through a diode to energize a holding coil, which maintains the contactor in its current state. This converts what would be wasted energy into a useful function, eliminating the need for continuous power consumption while maintaining state.
Solution Approach 2:
The patent introduces a diode as an intermediary component to manage the harmful voltage transient. The diode directs the back EMF current flow to the holding coil, acting as a mediator that converts the potentially harmful voltage spike into a controlled current that performs the useful function of holding the contactor state.
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
Enables 50% faster state transitions without increasing coil size, utilizing higher current ratings within the same space, and effectively managing voltage transients to prevent damage to electronics and switches.
Implementation Method 1
A coil has first and second ends. The moveable actuator extends through the coil as a core. The coil is capable of moving the actuator when either a power-up input signal is received by the first input circuit or a trip input signal is received by the second input circuit.
Implementation Method 2
First and second switches are coupled to respective first and second ends of the coil for reversing the polarity of the coil each occurrence of the actuator being actuated.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A contactor includes a plurality of switches mechanically coupled to an actuator. The actuator is moveable between operational and tripped positions. Switches that are closed in the operational position are open in the tripped position, and vice versa. The actuator extends through a coil as a core. The coil moves the actuator when an input signal is applied to the coil. A first input circuit receives a power-up input signal to transition the contactor from a tripped position to an operational position. A second input circuit receives a trip signal to transition the contactor from the operational position to the tripped position. First and second switches, coupled to respective first and second ends of the coil, reverse the polarity of the coil each occurrence of the actuator being actuated in preparation for the coil to be energized and magnetically polarized in an opposite direction during a next subsequent actuation.