1. Problem description:
In the AC motor variable voltage variable frequency speed regulation system, the three-phase voltage inverter can be equivalently represented by the six switching elements shown in Figure 2.6. The phase voltage and line voltage of the motor depend on its corresponding inverter bridge arm. The state of the upper and lower six power switches, in the figure, is the DC bus voltage, and A, B, and C are the state quantities of the switches. It is stipulated that when each switch state quantity is 1, the upper bridge arm is turned on, when the switch state quantity is 0, the lower bridge arm is turned on, and the upper and lower bridge arms of each phase cannot be turned on at the same time. Then the different combinations of 6 switches can constitute 8 different working states of the inverter [36].
Figure 2.6 Voltage source three-phase inverter
The realization of the SVPWM control strategy is mainly divided into the following three steps, the judgment of the voltage space vector sector, the determination of the adjacent vector action time and the determination of the comparison time.
2. Part of the program:
function [sys,x0,str,ts] = func_XYZ_cal(t,x,u,flag)
switch flag,
case 0,
[sys,x0,str,ts]=mdlInitializeSizes;
case 1,
sys=[];
case 2,
sys=[];
case 3,
sys=mdlOutputs(t,x,u);
case 4,
sys=[];
case 9,
sys=[];
otherwise
error(['Unhandled flag = ',num2str(flag)]);
end
function [sys,x0,str,ts]=mdlInitializeSizes
sizes = simsizes;
sizes.NumContStates = 0;
sizes.NumDiscStates = 2;
sizes.NumOutputs = 2;
sizes.NumInputs = 3;
sizes.DirFeedthrough = 1;
sizes.NumSampleTimes = 1; % at least one sample time is needed
sys = simsizes(sizes);
x0 = [0 0];
str = [];
ts = [0 0];
%u(1)=Ud;u(2)=Uq;u(3)=cita;
function sys=mdlOutputs(t,x,u)
x (1) = cos (u (3)) * u (1) -sin (u (3)) * u (2);
x (2) = sin (u (3)) * u (1) + cos (u (3)) * u (2);
sys (1) = x (1); % Uafa
sys (2) = x (2); % Ubta
3. Simulation conclusion:
