fullup1
New member
- Joined
- Jun 5, 2003
- Location
- Blacksburg, VA
This is for a mechatronics project at school.
To ignore the specifics, the important question I have pertains to the wastegate pressure signal. I'm using a normally closed 3-way solenoid air valve to block the signal going to the wastegate, and I'm trying to send a PWM signal to the solenoid based on the desired boost specified by a potentiometer.
I have a Motorola MPX4250A pressure transducer for any closed-loop operation I want to perform, but so far I'm having problems just determining the PWM necessary for particular levels of boost.
As a for instance, I expect something like this:
100% duty cycle --> always open --> stock boost ~7.5psi
75% duty cycle --> 9 psi
50% duty cycle --> 12 psi
25% duty cycle --> 15 psi
0% duty cycle --> BOOM
Originally I tried to use the "error" between the desired boost pressure and the actual boost pressure to speed up the response of the turbocharger, but to no avail. I've considered using differential control by taking the error from two separate readings and based a PWM correction upon that, but I haven't even gotten the base PWM to work correctly.
Does anyone have any clever control ideas for how to determine what PWM signal should be sent to the solenoid? I have the necessary elements for closed-loop negative feedback, I just can't figure out how to force the output of the control loop to match the input (since I have no reference for how the dynamic response of the turbocharger can be modeled).
Any help would be appreciated.
To ignore the specifics, the important question I have pertains to the wastegate pressure signal. I'm using a normally closed 3-way solenoid air valve to block the signal going to the wastegate, and I'm trying to send a PWM signal to the solenoid based on the desired boost specified by a potentiometer.
I have a Motorola MPX4250A pressure transducer for any closed-loop operation I want to perform, but so far I'm having problems just determining the PWM necessary for particular levels of boost.
As a for instance, I expect something like this:
100% duty cycle --> always open --> stock boost ~7.5psi
75% duty cycle --> 9 psi
50% duty cycle --> 12 psi
25% duty cycle --> 15 psi
0% duty cycle --> BOOM
Originally I tried to use the "error" between the desired boost pressure and the actual boost pressure to speed up the response of the turbocharger, but to no avail. I've considered using differential control by taking the error from two separate readings and based a PWM correction upon that, but I haven't even gotten the base PWM to work correctly.
Does anyone have any clever control ideas for how to determine what PWM signal should be sent to the solenoid? I have the necessary elements for closed-loop negative feedback, I just can't figure out how to force the output of the control loop to match the input (since I have no reference for how the dynamic response of the turbocharger can be modeled).
Any help would be appreciated.