Contactor Coil Control Circuit With Redundant Breaking Logic
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Solution Overview
Problem
Existing contactor control systems face challenges in ensuring safe stop functions, particularly when software failures occur, leading to potential safety hazards and increased maintenance complexities.
Innovation Solution
A control circuit for a contactor that includes a pulse converter, a first controller, a second controller, and a coil driver, where the second controller provides a redundant breaking control signal to ensure safe braking even if the first controller fails, thereby enhancing safety guarantees.
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 is hard to achieve and higher safety guarantee cannot be provided
Solution Approach 1:
The control system is segmented into two independent controllers: a first controller that monitors digital input control signals and generates breaking control signals, and a second controller that directly detects the control signal to generate 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 pre-prepared backup mechanism that activates when the first controller fails. By having this redundant control path established in advance, the system cushions against software failures and ensures safe stop functionality is maintained.
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 large current contactors which increases the use cost
Solution Approach 1:
The control circuit is designed with multi-functional capability to handle both small and large current contactors universally. The first and second controllers can adapt to different current levels by configuring their output capabilities, eliminating the need for additional relays and maintaining simplicity across different applications.
3Extent of automation
If software embedded in microcontroller is used for digital input control, then the control is achieved through software, but the software needs to be authenticated which makes update or maintenance troublesome
Solution Approach 1:
The control system is divided into first controller (software-based) and second controller (hardware-based) functions. The second controller implements breaking control through hardware circuitry that directly detects control signals, eliminating the need for software authentication and simplifying maintenance while preserving automated control capabilities.
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 redundant breaking control mechanism ensures that the contactor can safely stop even in the event of software failure, providing a higher safety guarantee and reducing maintenance complexities.
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
Figure 1~2
Figure 3(a)~3(d)
Figure 4
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.