I am trying to filter out my PWM frequency to produce a variable DC supply to my load.
R is a halogen bulb, at rated power and voltage R is 3.84 ohms.
Pwm freq = 25Khz
I stuck in a coil and fly-back diode and after fiddling with the inductor value just a few times i seem to have happened upon a suitable solution.
Though in my experience, things don't just happen - hence my post here for validation.
With R = 3.84 and L = 2 mH the cut-off frequency is around 300hz and i can vary the duty in my simulation to get a varied average dc output.
THe above image shows the load current with the lowest permissible PWM duty and the largest ripple current.
The following image shows the duty around its max with the ripple noticeably reduced.
So i am just looking to clarify that a simple coil in series with my load used with a fly-back diode is all i need to feed variable DC to my bulb from a PWMed DC supply.
I have looked briefly online for a part that meets my required specifications (assuming they are correct) and seem to have found some viable options, though all the coils seem rather large.
Any guidance is appreciated.
I am trying to create a small halogen dimmer essentially, and attempting to reduce the noise emissions by filtering and shielding.
Thanks AAC!
R is a halogen bulb, at rated power and voltage R is 3.84 ohms.
Pwm freq = 25Khz
I stuck in a coil and fly-back diode and after fiddling with the inductor value just a few times i seem to have happened upon a suitable solution.
Though in my experience, things don't just happen - hence my post here for validation.
With R = 3.84 and L = 2 mH the cut-off frequency is around 300hz and i can vary the duty in my simulation to get a varied average dc output.
THe above image shows the load current with the lowest permissible PWM duty and the largest ripple current.
The following image shows the duty around its max with the ripple noticeably reduced.
So i am just looking to clarify that a simple coil in series with my load used with a fly-back diode is all i need to feed variable DC to my bulb from a PWMed DC supply.
I have looked briefly online for a part that meets my required specifications (assuming they are correct) and seem to have found some viable options, though all the coils seem rather large.
Any guidance is appreciated.
I am trying to create a small halogen dimmer essentially, and attempting to reduce the noise emissions by filtering and shielding.
Thanks AAC!