Pulse Width Modulated (PWM) Power SuppliesBy
- V. Quercioli, Florence, Italy
A restricted source of power supply is analysed in this book - namely the switching mode power supplies (SMPS), which utilise the Pulse Width Modulation (PWM) technique to operate. Even though restricted, such a class of power supply is vital to circuits as most of modern electronic equipment is dependant on this form of technology to feed electronic boards. Its main advantages are greater efficiency, and its minimum physical size and weight.
Interdisciplinary knowledge such as circuit theory, semiconductor devices theory and technology, magnetics theory and technology, linear and nonlinear control theory is involved in the design of an SMPS.
This volume provides designers with an in-depth overview on the latest interdisciplinary methods involved in the design of switching mode power supplies, providing the reader with a tool whereby the learning time can be reduced and information about switching mode power supplies design processes can be easily accessed. The book adopts a systemic approach, subdividing the information into functional blocks whose properties and relationships are evaluated and compared with each other. A comprehensive list of references to the literature is given thus enabling the reader to follow up on more detail.
Studies in Electrical and Electronic Engineering
Published: April 1993
- 1. The Power Supply System. Power supply parameters. Linear vs. switching power supplies. Voltage mode, voltage feedforward, current mode. 2. The Input Stage. The basic ac/dc converter. Bulk capacitor sizing. The computation of ton. The inrush current problem. The bridge diodes sizing. The power factor. The EMI problem. EMI filtering. 3. The Flyback Converter. Output voltage computation. Computation of Dmax. Computation of Lp. Comparison between DM and CM. The transformer. Sizing of the core. Computation of the secondary winding number of turns, Ns. Parasitic interactions between the switching transistor and the transformer. Transient switchings. D-phase power losses in the MOSFET. Resultant waveforms. MOSFET transistor sizing. Output diode. 4. The Forward Converter. Output voltage computation. Computation of Dmax. The transformer. Parasitic interactions between the switching transistor and the transformer. Output and demagnetization diodes. 5. The Push-Pull Converter. Output voltage computation. The "volt-seconds" problem. The transformer. Semiconductor switch. Output diodes. The "half bridge" variant. Computation of the half bridge's capacitances. Cascaded push-pull. 6. The Output Stage. The filter capacitor. The C filter. The LC filter. The coupled inductor. Comparison "Independent inductors vs. coupled inductor". Design conclusions. Postregulators. Magnetic amplifier. Desaturation of the magnetic amplifier. The magnetic amplifier's control-to-output transfer function. The mag amp's delay problem. Mag amp compensation. 7. SMPS Control Theory. Electrical circuits modelling. Calculation of the transfer function. Frequency response. Control targets. Controller design. Conclusions. Compound excitation signals. Switching networks. Control techniques. Voltage mode techniques. Input voltage feedforward control. From voltage mode to current mode: the conductance control. Conductance control loop analysis. Voltage mode loop analysis. Current mode: the peak current control. Slope compensation. Control loop insulation by optocouplers. The right half plane zero. Output impedance computation. References.