Hi,
Windmill MPPT is a complex problem unlike solar or hydro. A Brazilian Master Thesis is suggesting the reading of wild AC coming off the mill to drive a SEPIC buck/boost converter via PWM and to charge batteries that way.
The sampling of V and Amp is done within the sine curve with its high-frequency harmonics to get at the instantaneous DC power component. This is one signal.
The other signal is the RPM figure, which is put into a look-up table to get at the power to be produced. These two signals are subtracted and the error value drives the PWM.
Googling for "first-order low-pass filter" Wikipedia enlightened me how the digital simulation of this filter can be done:
y(i) are the output power samples,
x(i) are the input power samples,
dt or deltat is the time interval between samples,
RC is the time constant of the filter, and
n is the number of samples.
alpha = dt / (RC + dt)
for i = 1 to n
y(i) = y(i - 1) + alpha * (x(i) - y(i - 1))
Or: "The change in filter output is proportional to the difference between the last output and the current input"
Questions:
1. Assuming a mill AC frequency of 100 Hz, how many n samples should be considered?
2. Time constant of RC filter?
3. Sample interval called dt?
Anyone out there who can solve this? Is there a connection to Nyquist's sampling theorem i have come across once?
Thanks.
Windmill MPPT is a complex problem unlike solar or hydro. A Brazilian Master Thesis is suggesting the reading of wild AC coming off the mill to drive a SEPIC buck/boost converter via PWM and to charge batteries that way.
The sampling of V and Amp is done within the sine curve with its high-frequency harmonics to get at the instantaneous DC power component. This is one signal.
The other signal is the RPM figure, which is put into a look-up table to get at the power to be produced. These two signals are subtracted and the error value drives the PWM.
Googling for "first-order low-pass filter" Wikipedia enlightened me how the digital simulation of this filter can be done:
y(i) are the output power samples,
x(i) are the input power samples,
dt or deltat is the time interval between samples,
RC is the time constant of the filter, and
n is the number of samples.
alpha = dt / (RC + dt)
for i = 1 to n
y(i) = y(i - 1) + alpha * (x(i) - y(i - 1))
Or: "The change in filter output is proportional to the difference between the last output and the current input"
Questions:
1. Assuming a mill AC frequency of 100 Hz, how many n samples should be considered?
2. Time constant of RC filter?
3. Sample interval called dt?
Anyone out there who can solve this? Is there a connection to Nyquist's sampling theorem i have come across once?
Thanks.