Controlling a Solenoid with an Arduino

Projects General Guidance
1

Hi,

For my project, I need a solenoid that I will control with an Arduino. The solenoid will be mounted on the gripper of a UR5e arm. It will be energized for approximately 1s or 2s and then stop for 5s to cool down, leading probably to a duty cycle of around 20-10%.

The system will likely run continuously for 24 hours, so it needs to be as safe and robust as possible.

I’ve already prepared an electrical plan for this, but I’m not sure if it’s robust enough. Should I add any additional safety measures?

Solenoid: 12V - 4.2W

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MOSFET: IRLZ44N (Logic-Level N-Channel MOSFET): UDS: 55 V - Id: 47 A - RDS(on): 22 mOhm - Ptot: 110 W

Flyback Diode:: MUR460 600V, 4A

Fuse: SMD 2410 slow-blow 4A - 125V DC - (100A)

Questions:

  • If I energize the solenoid for 1 second and stop for 15 seconds, that results in a duty cycle of 1/16 = 6.25%. Would the solenoid draw more than the 42W (42W/12V=3.5A) specified in the datasheet? If so, would this be a problem?

  • Is the gate resistor placed correctly?

  • I plan to solder everything on a soldering board. Would using a breakout MOSFET module be advisable here, or is it unnecessary since I’m already using a flyback diode, fuse, and pull-down resistor?

  • Is a capacitor necessary here, considering the power supply should provide 12V at 5A, which matches the solenoid’s maximum specifications?

Below is the circuit diagram for reference:
The diode is used as a visual feedback.

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2

R3 will send 26 mA through the LED. 1K might be needed.
D3 should have a 10 k pulldown to GND.
R2 is preferably lower, 180 - 220 Ohm.

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3

No.

The resistance of the solenoid is 34Ω.
When powered from a 12V supply, the current will be 12V / 34Ω = 0.353A

The table is saying that if you are using the solenoid at 10% duty cycle, then the power can be 42W (so that the average power is 4.2W).

The voltage needs be raised up to 38V to achieve that power.
At 38V, current = 38V / 34Ω = 1.118A
That power of 42W is obtained from 38V x 1.118A, and not 12V x 3.5A as you suggested.

At 12V the current will be 353mA.

4

I think the voltage drop across LED D2 will keep the MOSFET from turning ON.

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5

Yes, and the Diode will never light up.

6

so in such case a power supply of 12V and 5A would be more than enough for this solenoid right? and the fuse of 4A is also good choice for safety?

7

I removed the gate Diode and adjusted the resistors

8

If heatingof the solenoid iis a problem, consider using PWM to pull in and hold the load.

100% duty-cycle for 100-200ms to ‘grab and hold’, then dropping back to. lower rate once the ‘work’ is done, simply to sustain the grip.

9

Why would you pick a fuse ten times higher than the nominal current?

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10

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