I need to PWM control two electromagnet groups where each group has four electromagnets. Emagnets have nominal 24V 0.33A current ratings. Here is the only datasheet I could find. To supply all the magnets I want to use this 24V 4A single power supply. To model these, I drew the schematics in my mind and simulated it as follows:
To model emagnets each drawing 0.33A current, I used 72Ohm and 1u inductor. I also added 1N4148 as a flywheel diode to each magnet.
The idea is two PWM outputs of a micro-controller like Arduino's will control(by two potentiometers as analog inputs of the uC) each two groups's PWM input hence the magnet current. Since the uC does not have 8 separate PWM outputs, each PWM is triggering four gates of the MOSFETs as shown in the diagram above.
In simulation I obtain the following power plot for this MOSFET I plan to use:
I have the following questions as concerns before I start soldering:
1-) Is it fine as in my diagram to connect all the gates at a point and trigger four MOSFETs from a single input?
2-) Are the gate resistors values for R_g1, Rx_1, R_g2, Rx_2 correct/sufficient?
3-) It seems I wouldn't need heat sink by looking at average power dissipation. But I wonder if I should change the PWM frequancy. Currently it is 490Hz. Would it make sense to increase it to 30KHz for instance to prevent ringing sound or another issue?
Using a non-inverting driver TL427:
I reduced MOSFETs(one for each group) and diodes(I used 1N4007)
Here is the power plot for one transistor in between 1.15ms and 1.2ms: