Contactor Control Circuit Using Dual Controllers for Safe Coil Break
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Solution Overview
Problem
Existing contactor safety stop functions face challenges with direct power supply control being limited to smaller currents and digital input control relying on software, which can fail, compromising safety and requiring frequent authentication.
Innovation Solution
A control circuit with a pulse converter and dual controllers, where a first controller generates a breaking control signal and a second hardware controller provides redundant breaking control, ensuring safe braking even if the first controller fails, and avoiding software authentication issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital input control with software monitoring is used, then the control manner can be adapted for contactors with all current levels and the cost is lower, but when the software fails, the safe stop of the contactor cannot be achieved and higher safety guarantee cannot be provided
Solution Approach 1:
The control circuit is segmented into two independent controllers: a first controller that monitors digital input control signals and generates first breaking control signals, and a second controller that independently monitors the same control signals and generates second breaking control signals. This segmentation ensures that software failure in one controller does not compromise the overall safety system.
Solution Approach 2:
The second controller serves as a preemptive safety mechanism that is ready to activate before actual failure occurs. By having a redundant breaking control path established in advance, the system cushions against potential software failures in the primary controller, ensuring safety is maintained even if one controller fails.
2Ease of operation
If direct control of the power supply is used, then the control manner is simple and direct, but it is only directly adapted for the contactor with a smaller current in the coil and an additional relay needs to be used for larger currents which increases the use cost
Solution Approach 1:
The control circuit is designed with universal adaptability to handle different current levels through its dual-controller architecture. The first and second controllers can independently manage breaking control signals for various current specifications without requiring additional relays or complex external circuitry, making the same control circuit universally applicable across different contactor current ratings.
3Extent of automation
If software embedded in microcontroller is used for digital input control, then the control can be implemented, but the software needs to be authenticated which makes update or maintenance troublesome
Solution Approach 1:
The control functionality is segmented between two controllers with different implementation approaches. The first controller uses embedded software for automated control, while the second controller provides breaking control through a different mechanism. This segmentation allows the software in the first controller to be updated and maintained independently without affecting the overall system safety, as the second controller provides independent verification and control capability.
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
The dual-controller system ensures higher safety guarantees by providing redundant breaking control and preventing software failure-induced contactor malfunction, enhancing safety and reducing maintenance burdens.
Implementation Method 1
when the coil of the contactor is energized, the current in the coil will generate the magnetic field
Implementation Method 2
the current in the coil will generate the magnetic field which causes a static iron core to generate an electromagnetic attraction force which attracts the iron core
Data Source
AI summary
Embodiments of the present disclosure relate to a control circuit for a contactor and a control method thereof. The control circuit comprises: a pulse converter configured to convert a turn-on control signal into a continuous pulse signal; a first controller configured to generate a first breaking control signal at a first time in response to detection of the disappearance of the continuous pulse signal received from the pulse converter; a second controller configured to generate a second breaking control signal at a second time in response to detection of the disappearance of the continuous pulse signal received from the pulse converter, wherein the first time is earlier than the second time; and a coil driver configured to turn off a current of the excitation coil according to the received first breaking control signal, and if the current is not turned off according to the first breaking control signal, to further turn off the current of the excitation coil according to the second breaking control signal, thereby realizing the breaking of the main contact.