Multi-Stage Contactor Coil Ride-Through for Voltage Dips
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Solution Overview
Problem
Industry processes are vulnerable to shutdowns due to momentary low voltage events, causing motor disconnects and significant production losses, with existing solutions like converting AC coils to DC coils or using constant voltage transformers being costly and invasive.
Innovation Solution
A hybrid multi-stage device using resistor-inductor-capacitor (RLC) circuits with control power transformers (CPT) and under-damped RLC stages to maintain motor operation during voltage dips, without requiring batteries or rectifiers/inverters, by charging the contactor coil and discharging energy to sustain magnetic field strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solutions like converting AC coils to DC coils or using constant voltage transformers are implemented, then motor reliability during voltage dips is improved, but device complexity and cost increase
Solution Approach 1:
The RLC circuit is pre-charged to stored energy levels during normal operation through the control power transformer. When a voltage dip is detected, the pre-charged RLC circuit immediately discharges to maintain contactor coil operation, eliminating the need for complex real-time power conversion systems.
Solution Approach 2:
The RLC circuit acts as an intermediary energy storage device between the power source and the contactor coil. It absorbs excess energy during normal voltage conditions and releases it during voltage dips, mediating the power transfer without requiring complex AC-DC conversion or constant voltage transformation.
2Reliability
If battery-based uninterruptible power supplies are used, then motor reliability during voltage dips is improved, but device complexity and cost increase
Solution Approach 1:
The RLC circuit uses passive electrical components (resistors, inductors, capacitors) that are simpler and less expensive than battery systems. The circuit provides sufficient ride-through capability for the duration of tolerable voltage dips without requiring rechargeable energy storage devices, rectifiers, or inverters.
Solution Approach 2:
The invention replaces the mechanical/chemical battery-based power supply system with an electrical RLC circuit system. This substitution eliminates the need for complex battery management, rectification, and inversion electronics while achieving the same protective function.
3Duration of action of moving object
If multi-stage RLC circuits are implemented, then ride-through duration is extended, but device complexity increases
Solution Approach 1:
The power supply system is divided into multiple independent RLC circuit stages, each capable of providing a portion of the total ride-through duration. The stages can be configured in series or parallel to achieve the desired total duration, allowing modular extension of protection time without requiring a complete system redesign.
Solution Approach 2:
Each RLC circuit stage serves multiple functions: energy storage, voltage regulation, and transient suppression. The same basic RLC topology can be replicated and combined to provide different ride-through durations, making the design universally applicable to various voltage dip scenarios without requiring different circuit architectures.
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 low-voltage ride-through capabilities for motors, preventing costly shutdowns and ensuring seamless operation during tolerable voltage dips, without the need for additional power supplies, and is scalable for customized ride-through times.
Implementation Method 1
connecting the RLC circuit to the contactor coil during a low-voltage event to discharge the RLC circuit and charge the coil
Implementation Method 2
resistor-inductor-capacitor (RLC) circuit stages
Implementation Method 3
charging one or more resistor-inductor-capacitor (RLC) circuit stages using control power transformer (CPT)
Implementation Method 4
a voltage monitor electrically connected to the contactor coil to sense voltage across the contactor coil
Data Source
AI summary
Systems, methods, and apparatuses include an alternating current (AC) contactor comprising a contactor coil, the AC contactor configured to selectively connect a power source to a motor, a controller power transformer (CPT) electrically connected to the contactor coil by a CPT switch, a resistor-inductor-capacitor (RLC) circuit electrically connected to the contactor coil by an RLC circuit switch, a voltage monitor electrically connected to the contactor coil to sense voltage across the contactor coil, and a switch controller to active the RLC circuit switch to selectively connect the RLC circuit to the contactor coil during a low-voltage event determined by the switch controller from voltage across the contactor coil sensed by the voltage monitor. The RLC circuit can discharge stored electrical energy to power the contactor. A second RLC circuit can be included in the apparatus and controllably discharged to extend the low-voltage ride-through.