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Altera_Forum
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14 years ago

PI controller in VHDL

I'm trying to implement a PI controller in VHDL. where i tried a lot but i failed Please, can any one help me to achieve this task where i'm new in this field.
Altera_Forum's avatar
Altera_Forum
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14 years ago

The PI controller algorithm presented by maha.eg can be found quite often in literature, it's also quoted as velocity algorithm, because the controller output u(k)-u(k1) represents the change rate of manipulated value. It's main advantage is that it allows to stop integration exactly at the limits of the manipulated value u(k).

Besides the shown variant of the algorithms, which refers to trapezoidal integration, there's also a rectangular integral variant. My digital control text book mentions, that the difference between both is neglectable for short sample periods.

u(k)=u(k-1) + err(k)*kp + err(k-1) * (ki*ts - kp)