Control of a High Voltage DC Modulator for an Industrial Magnetron

Industrial magnetrons require high voltage DC supply (anode power supply) for its operation. Magnetrons are expensive and sensitive to variations in terminal voltage. Generally a soft start procedure is adopted to save the magnetrons that requires a specific pulse shape and transient behaviour of the power supply. This paper implements PI control for a previously designed power supply to make it reliable for a 10 kW magnetron. The requirements and issues are discussed in detail with respect to unregulated resonant DC power supply and it is argued that PI control is an attractive choice for its simplicity. Simulations are performed in PSIM and MATLAB-SIMULINK using real values of the circuit components and the controller is applied to the circuit instead of a mathematical model. Hence the work presented in this paper provides a strong foundation for the realization of the practical system. The controller is evaluated rigorously for line and load regulation and other transient characteristics. The proposed PI control is found very promising for the intended application and the resonant DC power supply design presented previously.