Coil Actuator PWM Control Eliminates Electrolytic Capacitors
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Solution Overview
Problem
Current single coil actuators for low and medium voltage applications face reliability issues due to the use of electrolytic capacitors, which are prone to electrical stresses and in-rush currents, leading to potential failure and reduced operating life.
Innovation Solution
A coil actuator design featuring a power and control unit with a PWM controller that adjusts input current reference values based on input voltage thresholds, eliminating the need for electrolytic capacitors by managing excitation current levels through multiple reference values and duty-cycle control, thereby enhancing reliability and extending operational life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electrolytic capacitors are used to store electric energy in the driving electronics, then the actuator can handle variable input voltages, but the reliability decreases due to electrical stresses and in-rush currents
Solution Approach 1:
The patent removes electrolytic capacitors from the driving electronics circuit. The energy storage function previously performed by capacitors is replaced by direct control of the power switch based on PWM signals, eliminating the source of reliability problems while maintaining the ability to handle variable input voltages
Solution Approach 2:
The patent changes the control parameter from passive capacitor-based energy storage to active PWM duty-cycle control. By adjusting the duty cycle of the power switch, the system can adapt to variable input voltages without requiring capacitors, thus improving reliability while maintaining adaptability
2Device complexity
If a single coil winding is used instead of dual windings, then the device complexity is reduced, but the control precision for launch and hold operations may be compromised
Solution Approach 1:
The patent uses dynamic PWM control to adjust the duty cycle of the power switch, enabling the single coil to provide different average currents for launch and hold operations. This dynamic control compensates for the lack of separate windings, maintaining operational precision while simplifying the coil structure
Solution Approach 2:
The patent changes the control approach from separate windings with distinct connections to a single winding with variable duty-cycle control. By modifying the duty cycle parameter, the system achieves different current levels (launch current and hold current) with a simpler single-coil structure
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 provides a reliable and long-lasting coil actuator with a simplified design, capable of handling variable input voltages without electrolytic capacitors, ensuring higher reliability and extended operational life while maintaining performance and being cost-effective for industrial manufacturing.
Implementation Method 1
a coil electromagnet (2) provided with a single coil winding (21)... a power and control unit (3)... operatively coupled with said coil electromagnet (2) to control an average value of an excitation current (IE) flowing along said coil electromagnet (2)
Implementation Method 2
coil electromagnet (2) provided with a single coil winding (21)... a movable anchor (22)... to move said movable anchor (22) from a rest position to an actuated position upon the application of an actuation force
Data Source
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AI summary
A coil actuator (1) for low and medium voltage applications comprising a coil electromagnet (2) provided with a single coil winding (21) and a movable anchor (22) and a power and control unit (3) comprising: - a power circuit (4) operatively coupled with said coil electromagnet (2), said power circuit comprising input terminals (T1, T2), at which said power circuit receives an input voltage (VIN); - a PWM controller (6) operatively coupled with said power circuit (4), said PWM controller being adapted to control an input current (IIN) flowing through said power circuit (4) to obtain and maintain an average operating level (IL, IH) selected an excitation current feeding said coil electromagnet. Said PWM controller (6) is adapted to set a plurality of reference values (I1, I2, I3) for said input current (IIN) to control said input current (IIN), each reference value (I1, I2, I3) for said input current (IIN) being selected among said plurality of reference values depending on the behavior of said input voltage (VIN).