Three-Phase Precision AC Power Supply Of Seeker Gyro

A detailed theoretical analysis and research was performed on the 3-phase precisionpower supply of gyro, which is based on the switching-node-preset PWM controlstrategy. Several switching-node-preset PWM modes were compared and analyzed. Aset of switching nodes of Selective Harmonic Elimination (SHE) PWM mode hasbeen worked out , with which the PWM waveform characterizes low THD, high DCvoltage utilization ratio and very low low-order harmonics. The principle of SHEPWM, method of SHE PWM equation solution was given meanwhile. The output ACfilter was analyzed in details. The research focused on the influence of LCparameters on the filter output capacity, and the outcome provides a reasonableprinciple of filter design. In order to promote the performance of the output voltageand the response of the system, a kind of current-regulated with voltage controlledPWM strategy was used, and the feedback control circuit based on UC 1842 wasdesigned primarily. Some other relative circuits were also researched and designedsuch as voltage regulator, the circuit producing SHE PWM signal, the PWM drivingcircuit and the detecting circuit of AC voltage. At last a computer simulation wasmade to the open-loop system, confirming the selection of the switching nodes and themain design. Simulation results were satisfactory.