Switching Device Control with Separate Start-up and Holding Coils
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Solution Overview
Problem
Switching devices for large loads, such as contactors, face challenges in electromagnetic compatibility (EMC) due to the generation of high-frequency electromagnetic interference from pulse width modulated (PWM) voltages used in both start-up and holding processes, and require multiple reference potentials and complex circuitry for voltage supply management.
Innovation Solution
A control device with separate start-up and holding coils, utilizing a direct voltage supply unit and rectifier to provide a common reference potential for the holding coil and control electronics, and a direct voltage converter to generate specified direct voltages, allowing for a direct voltage supply to the holding coil and control electronics, reducing electromagnetic interference and simplifying voltage management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM voltage is used for both start-up and holding processes, then the switching device can be controlled effectively, but high-frequency electromagnetic interference is generated causing poor EMC behavior
Solution Approach 1:
The patent divides the single coil into two separate coils: a start-up coil and a holding coil. The start-up coil receives PWM voltage for effective switching control, while the holding coil receives direct voltage to maintain the switched state without generating high-frequency electromagnetic interference. This segmentation allows each coil to be optimized for its specific function, resolving the contradiction between effective control and EMC behavior.
2Ease of manufacture
If separate reference potentials are used for holding coil and control electronics, then voltage supply management can be achieved, but circuit complexity increases
Solution Approach 1:
The patent merges the reference potentials of the holding coil and control electronics into a common reference potential. This is achieved by connecting the negative terminal of the holding coil to the same reference point as the control electronics ground. By combining the reference potentials, the patent simplifies the circuit architecture while still enabling independent voltage supply management through separate positive terminal connections to the holding coil and control electronics.
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
This solution improves EMC behavior, reduces component complexity, and allows a single holding coil to be used across various voltage variants and device sizes, maintaining consistent EMC performance and reducing the number of required components.
Implementation Method 1
a rectifier (22) configured to generate a rectified output voltage from an alternating voltage for supplying the start-up coil (14)
Implementation Method 2
a direct voltage converter (20), connected to a rectifier output, configured to generate a specified direct voltage for the direct voltage supply unit (18) from an output voltage of the rectifier (22)
Implementation Method 3
a second PWM voltage for the contact module's holding process is generated in the holding circuit, which is supplied to the contact module's coil during the switching device's holding operation
Implementation Method 4
a first PWM voltage for supplying the start-up coil (14) with voltage during the contact module's start-up process
Data Source
AI summary
A control device for a switching device with separate start-up and holding coils includes control electronics to control the current supply to the start-up and holding coils and a direct voltage supply unit for the holding coil and the control electronics with the same reference potential for the holding coil and the control electronics.