Abstarct: Abstract To keep the output voltage of photovoltaic systems constant, DC to DC converters are used, considering the characteristics of the high order DC to DC converter consisting of the second order step-up converter and capacitor switch, it is a good option to do this. The better the control of the converter is, it increases the efficiency of the existing system. The control process is on a seventh order system. In this thesis, the aim is to control the output voltage of the high-order DC-to-DC converter consisting of a second-order step-up converter and a capacitor switch using the linear integral quadratic regulator method.Therefore, after introducing the above converter, the state space model of the system is expressed around the working point, and the control is designed by the linear integral quadratic regulator method for the output voltage, and then the performance result of the above controller is compared with the PID controller and the superiority It shows the control by the quadratic linear integral regulator method.