Nonlinear control for buck switching power supplies using opto-couplers in the stabilization feedback loop

作者：Bizon N^*; Sofron E; Raducu M; Oproescu M

来源：Optoelectronics and Advanced Materials-Rapid Communications, 2010, 4(6): 788-794.

• PWM voltage control
• Switching power supplies
• Nonlinear control
• Opto-coupler
• Chaotification
• Spread power spectrum
• Output voltage ripple

Buck switching power supplies usually use a PWM voltage control to stabilize the output voltage at the reference voltage level. If a classical PWM control technique is used, than high EMI noise peaks appear at the switching frequency and its harmonics. Spreading of the output voltage spectrum can be done, for example, by chaotification of the PWM command signal. This kind of the switching power supplies with low EMI is utilize in electronics equipments from different domains: medical, aeronautics etc. The proposed nonlinear control is based on the opto-coupler nonlinear characteristic included into nonlinear circuit of the feedback loop. The feedback nonlinear circuit assures a symmetrical nonlinear characteristic using two opto-couplers and a differential amplifier. The nonlinear characteristic is designed to minimize output voltage ripple. The nonlinear characteristic is initially modeled by a look-up table for an easy designing by changing of the characteristic parameters using trial and error method. The feasibility and effectiveness of this new and relative simple method is shown by simulation.

• 出版日期2010-6