Electromagnetic Coil Control via Variable Duty Cycle PWM
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Solution Overview
Problem
Electrical contactors face challenges in maintaining consistent operating times for movable contacts across different supply voltages, such as 110V and 220V, due to differences in voltage regulation, leading to variations in closing dynamics.
Innovation Solution
An electrical contactor with a pulse-width modulated signal for the electromagnetic coil, where the duty cycle of the signal varies over time based on measured voltage, ensuring consistent closing times by adjusting the coil's voltage control in response to changes in supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a low control setpoint voltage coil is used with high voltage supply (240V), then voltage adaptation is achieved, but significant current is consumed
Solution Approach 1:
The patent applies pulse-width modulation (PWM) to periodically switch the coil power supply, creating a series of voltage pulses rather than continuous DC voltage. This periodic action allows the coil to receive adequate energy for actuation while significantly reducing average current consumption compared to continuous voltage application.
Solution Approach 2:
The patent dynamically adjusts the duty cycle parameter of the PWM signal based on the actual supply voltage. By changing the duty cycle ratio (the proportion of time the voltage is applied within each pulse period), the system optimizes coil activation while minimizing current consumption across different supply voltage conditions.
2Device complexity
If voltage regulation is performed with fixed duty cycle, then control is simplified, but operating times vary between 110V and 220V supply voltages
Solution Approach 1:
The patent implements a feedback mechanism where the actual supply voltage is measured and used to dynamically adjust the PWM duty cycle. This closed-loop control ensures that the coil receives appropriate voltage regardless of whether the supply is 110V or 220V, maintaining consistent closing times while adapting to voltage variations.
3Reliability
If the output voltage of the rectifier is higher than the setpoint voltage, then coil control is effective, but average voltage calculation differs between 110V and 220V supply voltages
Solution Approach 1:
The patent transitions from static voltage control to dynamic PWM control, where the duty cycle continuously adapts to supply voltage conditions. This dynamic approach ensures that the average voltage delivered to the coil remains consistent regardless of whether the rectifier output is based on 110V or 220V input, maintaining reliable and stable coil operation.
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 solution ensures constant closing times for movable contacts across varying supply voltages, effectively regulating voltage and correcting for drops, thereby maintaining consistent operation and preventing incomplete contact closure.
Implementation Method 1
an electromagnetic coil capable of controlling the or each mobile contact in the closed position or in the open position
Implementation Method 2
the pulse-width modulated signal has a duty cycle of variable value over time, when controlling the or each movable contact in the closed position
Data Source
Figure 1
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Figure 4
AI summary
This electrical contactor (10) comprises at least one pair of fixed contacts (16) and, for each pair of fixed contacts (16), a movable contact (17) that can be moved between a closed position and an open position, and an electromagnetic coil (14) capable of controlling the or each movable contact (17) into the closed position or into the open position. The contactor (10) comprises an electronic module (13) for controlling the electromagnetic coil (14), the module comprising a switch (26) connected in series to the coil (14) and a device (28) for controlling the switch (26). The switch (26) comprises two conduction electrodes and one control electrode. The control device (28) comprises means (31) for calculating a pulse width modulated signal (S1) and means (32) for applying the calculated signal to the electrode controlling the switch (26). The pulse width modulated signal (S1) has a duty cycle of which the value varies over time when the or each movable contact (17) is controlled into the closed position.