# Hydraulic Generators

Discussion in 'General Electronics Discussion' started by HydraulicGen, Sep 14, 2017.

1. ### HydraulicGen

2
0
Sep 14, 2017
I am trying to come up with a solution to control a hydraulic proportional valve using either the output frequency of an ac generator or a pulse signal, basically I need the proportional valve to provide a constant flow to a hydraulic motor such that the driven speed of the hydraulic motor remains constant. So far all I have managed is to adapt the machine to provide a 600 pulse per second signal, what I need to do is to convert this to a dc voltage or current which signals the proportional valve to open and close responding to fluctuations in flow. Anyone out there know how to do this or can come up with a solution. At the moment I use a mechanical flow control valve, problem with this is that if you set the flow rate when the oil is cold the viscosity is x but when the oil is hot it is y so the driven speed of the ac alternator changes significantly.

4,299
1,158
Jun 25, 2010
3. ### Alec_t

3,050
830
Jul 7, 2015
Sounds as though you need to provide a signal proportional to motor speed, for use in a control loop to vary the valve position. Is the 600Hz signal a PWM one, with pulse width related to motor speed?

4. ### HydraulicGen

2
0
Sep 14, 2017
This signal is produced by a 12 tooth rotating plate fixed to the alternator / hydraulic motor drive shaft, the AC alternator is 50hz, 3000rpm, therefore generating a pulse signal of 600 pulses per second, I effectively need to maintain this irrespective of external factors, so therefore need to send a control signal to the proportional valve to adjust the valve accordingly. So yes the signal is directly proportionate to motor speed, motor runs slow pulse signal decreases and vica versa.

5. ### kellys_eye

4,299
1,158
Jun 25, 2010
As per my first post, the LM2907 performs all the necessary functions to deliver a proportional control voltage that you require. The scaling of the voltage can be achived partly by correct components associated with the LM2907 but also via simple level shifting using op-amps if necessary.

The resultant control voltage can also be used to control a range of other signal sources according to the needs of the hydraulic modulation vlave.

6. ### Alec_t

3,050
830
Jul 7, 2015
This would seem to be one approach :-
If you use the pulse signal to trigger a fixed-width pulse monostable you'd get a FM signal with a speed-proportional duty cycle. The partly-smoothed inverse of that could drive the valve directly. Pulsing of the valve is advantageous (as a well-known anti-stiction technique). Adjustment of the monostable pulse width would enable the desired speed to be set.