I would like to drive a bank of 20 solenoid valves (i.e. coils) with a PWM signal and I'm looking for any suggestions.
Here's a bunch of details for those interested.
I have some European proportional control solenoid valves that I want to put through their paces. The solenoid valves are air only and will be used at 15 bar. The solenoids run on 12 volts DC and I have 10 each of 2 different types. Type A has a 34.9 mH, 9.6 ohm coil and type B has a 21.2 mH, 6.1 ohm coil. Both of the solenoids draw a maximum average current of 1 amp when being driven with a PWM signal. The manufacturer uses an SPD25N06S2-40 N-channel MOSFET to drive each solenoid individually.
I am going to run these units until they fail and have programmed a complex PWM signal in to an arbitrary waveform generator. The PWM signal is normally on and runs at 200 Hz with a complex algorithm to vary the duty cycle. The maximum output of the arbitrary waveform generator is + and - 5 volts peak to peak. I am using a 12 volt, 60 amp power supply to drive the solenoids. My plan is to run all 10 "type A" solenoids in parallel with a high power driver circuit and run all 10 "type B" solenoids in parallel with a second duplicate circuit.
My initial thought was to make a little amplifier circuit to drive and bunch of FETs in parallel to switch the 12 volts with the PWM signal. I then recalled we had a 60 amp SSR (solid state relay) laying around so I hooked that straight up to the arbitrary waveform generator and it worked, but I don't like the slow response time of the SSR which is 1 millisecond. It's just far too slow for me. I am now thinking of using a 100-amp IGBT module to drive the solenoids.
Now the questions.
Question 1: Being quick and easy is more important than being inexpensive. So how would you suggest I drive the solenoids?
Question 2: The sales person for the solenoid valves told me NOT to use a reverse polarity diode to suppress the back EMF across the coils. He could not tell me why and did not know electronics well enough to convert the Swedish in to English. So I am thinking of using back to back zeners (two 15 volt zeners with the anodes connected together) instead of a reverse polarity diode. What do you think?
Thanks in advance for any help, comments or suggestions you may have.
Here's a bunch of details for those interested.
I have some European proportional control solenoid valves that I want to put through their paces. The solenoid valves are air only and will be used at 15 bar. The solenoids run on 12 volts DC and I have 10 each of 2 different types. Type A has a 34.9 mH, 9.6 ohm coil and type B has a 21.2 mH, 6.1 ohm coil. Both of the solenoids draw a maximum average current of 1 amp when being driven with a PWM signal. The manufacturer uses an SPD25N06S2-40 N-channel MOSFET to drive each solenoid individually.
I am going to run these units until they fail and have programmed a complex PWM signal in to an arbitrary waveform generator. The PWM signal is normally on and runs at 200 Hz with a complex algorithm to vary the duty cycle. The maximum output of the arbitrary waveform generator is + and - 5 volts peak to peak. I am using a 12 volt, 60 amp power supply to drive the solenoids. My plan is to run all 10 "type A" solenoids in parallel with a high power driver circuit and run all 10 "type B" solenoids in parallel with a second duplicate circuit.
My initial thought was to make a little amplifier circuit to drive and bunch of FETs in parallel to switch the 12 volts with the PWM signal. I then recalled we had a 60 amp SSR (solid state relay) laying around so I hooked that straight up to the arbitrary waveform generator and it worked, but I don't like the slow response time of the SSR which is 1 millisecond. It's just far too slow for me. I am now thinking of using a 100-amp IGBT module to drive the solenoids.
Now the questions.
Question 1: Being quick and easy is more important than being inexpensive. So how would you suggest I drive the solenoids?
Question 2: The sales person for the solenoid valves told me NOT to use a reverse polarity diode to suppress the back EMF across the coils. He could not tell me why and did not know electronics well enough to convert the Swedish in to English. So I am thinking of using back to back zeners (two 15 volt zeners with the anodes connected together) instead of a reverse polarity diode. What do you think?
Thanks in advance for any help, comments or suggestions you may have.