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SMPS Power Supply Topologies: Comparison and Selection

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SMPS Power Supply Topologies: Comparison and Selection SWITCHING MODE POWER SUPPLY (SMPS) TOPOLOGIES OVERVIEW, COMPARISON AND SELECTION GUIDE Home Tutorial Topologies SMPS diamond Thermal diamond Software PCB diamond Computer PSU UPSSpinTransformers Formulas EE Reference Inverters Generators Solar What is a power supply topology? Switch mode power supply (SMPS) circuits contain networks of energy storage inductors and capacitors as well as power handling transistors and rectifiers. Their particular configuration is referred to as a topology. Although there is a wide variety of converter topologies, only well-nigh a dozen vital ones are used in practical power design. They can be classified into two major families: whippersnapper and flyback depending on the method of operation. In the whippersnapper family energy is transferred from the input to the load during the conduction trundling of a switching transistor. In the flyback family the energy is piled during "on-state" of a switch and delivered to the output during the "off-state". Any practical spin belongs to one of these two configurations or their combination. Examples of the whippersnapper type are forward and underpass converters. Examples of the flyback type are inverting and uplift regulators. A well-constructed off-line PSU normally contains several conversion stages. Usually it is comprised of a rectifier section followed by a PFC uplift and one or increasingly downstream DC-DC converters. Each of them is usually controlled by a separate controller IC, although there are moreover PFC-PWM philharmonic ICs. The table unelevated summarizes and compares electrical features and characteristics of the main single-stage switching regulator circuits. This orchestration is followed by the DC to DC regulator selection guide. Converter topology Diagram DC transfer function (Vout/Vin) Max switch voltage Peak switch current Max rectifier voltage Average rectifier current Switch utilization ratio (SUR) NON-ISOLATING DC-DC CONVERTERSWhippersnapperD (0<D<1) Vin Iout Vin Iout×D Vout/VinUplift1/(1-D) (0<D<1) Vout Iout×Vout /Vin Vout Iout Vin/Vout Flyback (inverting) or buck-boost -D/(1-D) (0<D<1) Vin+|Vout| Iout× (1+|Vout|/Vin) Vin+|Vout| Iout |Vout|/Vin Ćuk -D/(1-D) (0<D<1) Vin+|Vout| Iout× (1+|Vout|/Vin) Vin+|Vout| Iout |Vout|/Vin Sepic D/(1-D) (0<D<1) Vin+Vout Iout Vin+Vout Iout Vout/ (Vin+Vout) ISOLATING DC-DC CONVERTERS DCM Flyback Vin2D2/ (2Lp×F×Iout) (0<D<1) Vin+Vout ×(Np/Ns) D×Vin/Lp×F Vout+ (Vin×Ns/Np) Iout DCM 2-switch flyback √(2Pout× LpF/Vin) (0<D<0.5) Vin D×Vin/Lp×F Vout+ (Vin×Ns/Np) Iout D/4 Forward Ns/Np×D (0<D<0.5) 2×Vin Iout×Ns/Np Vin×Ns/Np D1: Iout×D D2: Iout(1-D) (Vout/2Vin) ×Ns/Np 2-switch forward Ns/Np×D (0<D<0.5) Vin Iout×Ns/Np Vin×Ns/Np D1: Iout×D D2: Iout(1-D) (Vout/2Vin) ×Ns/Np Active clutch forward Ns/Np×D (0<D<1) Vin/(1-D) Iout×Ns/Np Vin×Ns/Np D1: Iout×D D2: Iout(1-D) Vout/Vin× (1-Vout×Np/ Vin×Ns) Half- underpass Ns/Np×D (0<D<0.5) Vin Iout×Ns/Np Vin×Ns/Np 0.5×Iout Vout/2Vin ×Ns/Np Push- pull 2Ns/Np×D (D<0.5) 2×Vin Iout×Ns/Np 2Vin×Ns/Np 0.5×Iout (Vout/4Vin) ×Ns/Np Full underpass 2Ns/Np×D (0<D<0.5) Vin Iout×Ns/Np 2Vin×Ns/Np 0.5×Iout (Vout/2Vin) ×Ns/Np Phase shifted full underpass 2Ns/Np×D (0<D<0.5) Vin Iout×Ns/Np Vin×Ns/Np 0.5×Iout (Vout/2Vin) ×Ns/Np LLC half underpass Ns/2Np (at F=Fres) Vin Iout×Ns/Np Vin×Ns/Np 0.5×Iout (Vout/2Vin) ×Ns/Np Notes: 1. All formulas are given for platonic circuits. Ripple currents, voltage spikes, power losses, voltage drops in MOSFETs and diodes are excluded. 2. Flyback equations are given for discontinuous conduction mode of operation (DCM). 3. For LLC converter the formulas are given for operation at resonance. 4. SUR is total switch utilization ratio specified as SUR=Pout/n×Vmax×Imax, where n- the number of power switches in the circuit, Vmax and Imax- their peak voltage and current. TOPOLOGY SELECTION CONSIDERATIONS. There is no single topology, which is weightier for all applications. The right switching power supply topology for a given using should be selected based on specific requirements for the power supply diamond including cost, size, time factors, and expected production volume. For example, for low-volume designs, the engineering expenses may be increasingly important than BOM cost. In this case, you may want to segregate a straightforward "textbook-based" tideway in which you are most experienced. Well executed trivial diamond is largest than poorly executed "fancy" one. Of course, while a vital diamond may be straightforward, meeting all of the safety and EMC regulatory specifications may still be a very time consuming task. For a high-volume production, you'll want to put uneaten engineering efforts in developing new solutions, minimizing component forfeit and turnout labor. When the functional requirements are pretty much conventional, the power level is usually the main factor that determines the topology selection. As an illustration, the table unelevated shows the configurations I would normally prefer for a downstream DC-DC converter in an offline switching power spin depending on its output power level. This selector guide is given for the power sources with output voltages unelevated 60V running off 120 to 400V DC-link (which are typical levels for rectified AC input line voltage or the output of a PFC boost). Note, all the information here is just a unstipulated guidance, which is based on the author's personal view.Moreoversee the latest inventions in SMPS topologies. 0-100 W, Iout<10 A 0-100 W, Iout>10 A 100-400 W 400-1200 W 1200-3000 W Single-switch flyback - - - - 2-switch flyback - - - - Active clutch flyback - - - - Single-switch forward - - - 2-switch forward - - Active clutch forward - - Half underpass - - LLC Half Brdige - - Full underpass - - - - Phase shifted ZVT full underpass - - - Note: At power levels whilom 3000W I would consider using multiple interleaved converters to spread heat dissipation. All info here is presented for reference only and does not constitute a professional advice- see a well-constructed Disclaimer linked below. 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