.PLL.Components.Basic3phasePLL .PLL.Components.Basic3phasePLL
The basic version of the three phase PLL assumes that a Clarke transformation is performed, then feeding the α- and β-component to this block.
Here a Park transformation on the inputs u[1..2] is applied, using the angle θ determined by the control loop.
The d- and the q-component are divided by the estimated amplitude to obtain an amplitude of 1.
Subsequently, the q-component is controlled to become 0, ie. determining the desired angle θ
as well as the frequency resp. angular velocity ω = 2 π f = w.
The output y[1] is a cosine signal in phase with the input u,
the output y[2] is a sine signal 90° phase shifted to y[1].
Result of the Clarke - Park - transformation can be inspected with u0, ud and uq.
Problems: especially a double-frequency ripple on the estimated frequency under distorted conditions, i.e. when the input signals contain not only a positive sequence but also a negative sequence and / or zero component. For symmterical components, see [Fortescue1918].