Author Topic: PVG32 Valve Plus 1 PWM  (Read 5684 times)

davszym

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PVG32 Valve Plus 1 PWM
« on: September 18, 2015, 12:31:00 AM »
I have an application where the client is using a third party controller to send a PWM signal to the PVG32 valve. They are having issues that occur when the voltage fluctuates on the machine. Specifically the PWM signals change erratically anytime something else on the machine causes the +DC to drop in voltage. It appears as if the current of the PWM signal is changing slightly based on the control voltage change.

I believe a Plus1 controller would remedy this issue because of the way the PWM signal is generated by the Plus 1. If I remember correctly, the PWM signal is monitored and adjusted for such changes in supply voltage that would affect the PWM signal and the PVG32 valve. Could someone confirm my theory that is the +12VDC to the Plus 1 fluctuates, but stays above 9VDC, the PWM control of the PVG32 valve will NOT be affected?

Thanks!

Offline Marbek_Elektronik

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Re: PVG32 Valve Plus 1 PWM
« Reply #1 on: September 18, 2015, 08:38:30 AM »
At first:
PVG32 actuators, like, PVEA, PVES, (not the old PVEM) can be drived on the signal pin with PWM (>1kHz) or with a constant DC-Voltage.
The relation between Signal voltage and power voltage will control the speed:
50% is 0
25% is -100%
75% ist +100%

For example: power voltage is 12V: average voltage on signal pin of 6V is no action, 3V is negative maximum speed, 9V is positiv maximum speed. Please look to the datasheet of the valves.
If you give 6V to signal, nothing happens. But if you change power voltage from 12V to 10V, you will change the ratio: 6V/10V =60% and the valve will work.

An easy way to control pvg valve is to use pwm and use the power supply. If power supply is not constant, the ratio of pwm and so the average voltage at signal pin  can't change the ratio. So this is OK.

I have build an application to drive PVEM with dc voltage at signal pin.
I have used an DA-IC and I take the supply voltage as referenz to this IC.
If power voltage changes, the dc voltage at signal pin changes in the same way.

If someone needs hardware to drive the old PVEM valves, he should ask me to help.

The normal way is to use danfoss controller with danfoss valves.
If this is not possible, please ask me for adapters or drivers for your controller and danfoss valve.
« Last Edit: September 18, 2015, 08:40:18 AM by Marbek_Elektronik »
Marbek Elektronik, Dipl.-Ing. Bernd Konrad
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davszym

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Re: PVG32 Valve Plus 1 PWM
« Reply #2 on: September 18, 2015, 03:26:12 PM »
I was just informed that this specific installation uses the PVHC option and not the PVE as I originally thought. Given that, and reading the PVHC literature I am lead to believe that the PVHC inherently is susceptible to these type of issue. So, even with the Plus 1, there may be an issue.