VOLTAGE ORIENTED CONTROL – SIMULATION
DC link voltage controller
DC link model and linearization
DC LINK MODEL The DC link voltage is modeled as a pure capacitor. This capacitor is an energy storage where
the stored electrical energy in Joule is 1
The time derivative of this stored energy should be equal to the sum of instantaneous grid power and load power  .
As we can see, the previous equation is not linear with respect to Vdc.
Figure 3.15 : Energy transfer
The design of the voltage controller is facilitated thanks a feedback linearization. The feedback linearization transforms the nonlinear dc voltage dynamics to a equivalent linear system, on which traditional linear controller design can be applied.
We now choose a new state variable
Then, equation (3.21) becomes
which is linear with respect to
. The physical interpretation is that the energy is chosen to
represent the dc link voltage dynamics instead of the voltage itself. Other type of linearization can
be found  .
3.5.2 Design of voltage controller
Â System transfer function Following  and the Internal Model Control method, we can write
is the d current, and the grid voltage
. The coefficient comes from the amplitude
invariant transformation (see section “2.2.2 Mathematical model” about power calculation).