VOLTAGE ORIENTED CONTROL – SIMULATION
3.2 System block diagram
The voltage oriented control scheme is shown Figure 3.2.
Figure 3.2 : System block diagram
First of all, the line voltage Uabc need to feed the PLL (Phase Locked Loop, see “3.7 Phase Locked Loop (PLL)”) and the voltage angle calculated is used for three phase to dq‐coordinate transformation of line current and voltage. Secondly, the dq‐coordinate values and the DC link voltage value are used in a decoupled controller which will be described in the section “3.4 Current controller” and “3.5 DC‐link voltage controller”. Finally, the reference voltages created by the controller are sent to the PWM block (Pulse Width Modulation) to create the switching patterns Sabc (S = 1 means upper switch ON, lower switch OFF ; S=0 means upper switch OFF, lower switch ON).
Remark : The reference voltage from the controller correspond to the converter voltage Us (see design of the current controller in section “3.4 Current controller”).
The system will be simulated in Matlab/Simulink. According to the previous figure, we will have four main parts in the model : the PLL, a decoupled controller composed by a current and voltage controller, a PWM block, and a rectifier model (with grid impedance R and L included).