Simulations and Practical Designs, Part II. Christophe book Switch-Mode Power SuppliesSPICE Simulations and Practical Designs. Switch-Mode Power SuppliesSPICE Simulations and Practical Designs _ EE wfhm.info - Download as PDF File .pdf), Text File .txt) or read online. Abstract: SwitchMode Power Supplies: SPICE Simulations and Practical Designs is a comprehensive resource on using SPICE as a power conversion design.
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Abstract: Switch-Mode Power Supplies: SPICE Simulations and Practical Designs is a comprehensive resource on using SPICE as a power conversion design. Switch-Mode Power Supplies SPICE Simulations and Practical Designs. INTUSOFT/IsSpice Simulation Libraries and Design Templates. Christophe Basso −. Switch-Mode Power Supplies SPICE Simulations and Practical Designs. OrCAD/ PSpice Simulation Libraries and Design Templates. Christophe Basso -
This type is widely used in power factor correction PFC applications. The type 3 amplifier introduces an integrator. Figure b plots the frequency response of the Fig. Two coincident pole-zero pairs associated with an integrator. As it does not offer any phase boost. As in any integral type compensation. We obtain the following expression.
The type 3 amplifier circuitry. Copyright McGraw-Hill. Switch-Mode Power Supplies. By adding the proportional term. All rights reserved http: The application field looks the same as for type 2. This is the case for CCM voltage-mode buck or boost-derived types of converters. We have seen that it prevents the output impedance from being too inductive.
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It features an origin pole, given by R 1 and C 1. In dc mode, when http: Rogers Ferreras Benitez. Jeshua Colon. Jafar Sadiq. Jack Daniel Jack.
[Read Book] Switch-Mode Power Supplies Second Edition: SPICE Simulations and Practical Designs
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Radu Chibzui. Oscar Pamos. Mnhug Infrastructurepresentation Phpapp Venkata Apparao S. Hugo Farro. Jeet Singh. Extremely large peak "in-rush" surge current limited only by the impedance of the input supply and any series resistance to the filter capacitors. Empty filter capacitors initially draw large amounts of current as they charge up, with larger capacitors drawing larger amounts of peak current.
Being many times above the normal operating current, this greatly stresses components subject to the surge, complicates fuse selection to avoid nuisance blowing and may cause problems with equipment employing overcurrent protection such as uninterruptible power supplies.
Mitigated by use of a suitable soft-start circuit or series resistor.
Risk of electric shock Supplies with transformers isolate the incoming power supply from the powered device and so allow metalwork of the enclosure to be grounded safely. Transformerless mains-operated supply dangerous. In both linear and switch-mode the mains, and possibly the output voltages, are hazardous and must be well-isolated. Two capacitors are connected in series with the Live and Neutral rails with the Earth connection in between the two capacitors. This forms a capacitive divider that energizes the common rail at half mains voltage.
Its high impedance current source can provide a tingling or a 'bite' to the operator or can be exploited to light an Earth Fault LED. However, this current may cause nuisance tripping on the most sensitive residual-current devices.
It can also provide some very mild tingling sensation but it's safe to the user . Risk of equipment damage Very low, unless a short occurs between the primary and secondary windings or the regulator fails by shorting internally.
Can fail so as to make output voltage very high.
Stress on capacitors may cause them to explode. Can in some cases destroy input stages in amplifiers if floating voltage exceeds transistor base-emitter breakdown voltage, causing the transistor's gain to drop and noise levels to increase. The floating voltage is caused by capacitors bridging the primary and secondary sides of the power supply. Connection to earthed equipment will cause a momentary and potentially destructive spike in current at the connector as the voltage at the secondary side of the capacitor equalizes to earth potential.
This is called rectification. In some power supplies mostly computer ATX power supplies , the rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically.
The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor. The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor. To correct for this, many newer SMPS will use a special PFC circuit to make the input current follow the sinusoidal shape of the AC input voltage, correcting the power factor.
This type of use may be harmful to the rectifier stage, however, as it will only use half of diodes in the rectifier for the full load. This could possibly result in overheating of these components, causing them to fail prematurely. The diodes in this type of power supply will handle the DC current just fine because they are rated to handle double the nominal input current when operated in the V mode, due to the operation of the voltage doubler. This is because the doubler, when in operation, uses only half of the bridge rectifier and runs twice as much current through it.
The inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz. Voltage converter and output rectifier[ edit ] If the output is required to be isolated from the input, as is usually the case in mains power supplies, the inverted AC is used to drive the primary winding of a high-frequency transformer.
This converts the voltage up or down to the required output level on its secondary winding. The output transformer in the block diagram serves this purpose. If a DC output is required, the AC output from the transformer is rectified. For output voltages above ten volts or so, ordinary silicon diodes are commonly used. For lower voltages, Schottky diodes are commonly used as the rectifier elements; they have the advantages of faster recovery times than silicon diodes allowing low-loss operation at higher frequencies and a lower voltage drop when conducting.
For even lower output voltages, MOSFETs may be used as synchronous rectifiers ; compared to Schottky diodes, these have even lower conducting state voltage drops. The rectified output is then smoothed by a filter consisting of inductors and capacitors. For higher switching frequencies, components with lower capacitance and inductance are needed. Simpler, non-isolated power supplies contain an inductor instead of a transformer. This type includes boost converters , buck converters , and the buck—boost converters.
These belong to the simplest class of single input, single output converters which use one inductor and one active switch.
The buck converter reduces the input voltage in direct proportion to the ratio of conductive time to the total switching period, called the duty cycle. A feedback control loop is employed to regulate the output voltage by varying the duty cycle to compensate for variations in input voltage. The output voltage of a boost converter is always greater than the input voltage and the buck—boost output voltage is inverted but can be greater than, equal to, or less than the magnitude of its input voltage.
There are many variations and extensions to this class of converters but these three form the basis of almost all isolated and non-isolated DC to DC converters. Other types of SMPSs use a capacitor — diode voltage multiplier instead of inductors and transformers.
These are mostly used for generating high voltages at low currents Cockcroft-Walton generator. The low voltage variant is called charge pump. Regulation[ edit ] This charger for a small device such as a mobile phone is a simple off-line switching power supply with a European plug. The simple circuit has just two transistors, an opto-coupler and rectifier diodes as active components.
A feedback circuit monitors the output voltage and compares it with a reference voltage, as shown in the block diagram above. Depending on design and safety requirements, the controller may contain an isolation mechanism such as an opto-coupler to isolate it from the DC output. Switching supplies in computers, TVs and VCRs have these opto-couplers to tightly control the output voltage.
Open-loop regulators do not have a feedback circuit. Instead, they rely on feeding a constant voltage to the input of the transformer or inductor, and assume that the output will be correct. Regulated designs compensate for the impedance of the transformer or coil.
Monopolar designs also compensate for the magnetic hysteresis of the core. The feedback circuit needs power to run before it can generate power, so an additional non-switching power-supply for stand-by is added. Transformer design[ edit ] Any switched-mode power supply that gets its power from an AC power line called an "off-line" converter  requires a transformer for galvanic isolation.
Some DC-to-DC converters may also include a transformer, although isolation may not be critical in these cases. SMPS transformers run at high frequency. There are additional design tradeoffs. The terminal voltage of a transformer is proportional to the product of the core area, magnetic flux, and frequency. By using a much higher frequency, the core area and so the mass of the core can be greatly reduced.
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However, core losses increase at higher frequencies. Cores generally use ferrite material which has a low loss at the high frequencies and high flux densities used. Also, more energy is lost during transitions of the switching semiconductor at higher frequencies.
Furthermore, more attention to the physical layout of the circuit board is required as parasitics become more significant, and the amount of electromagnetic interference will be more pronounced. For these frequencies, the skin effect is only significant when the conductors are large, more than 0.
Switching power supplies must pay more attention to the skin effect because it is a source of power loss. The effective resistance of conductors increases, because current concentrates near the surface of the conductor and the inner portion carries less current than at low frequencies.
The skin effect is exacerbated by the harmonics present in the high speed PWM switching waveforms. The appropriate skin depth is not just the depth at the fundamental, but also the skin depths at the harmonics.The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor.
The effective resistance of conductors increases, because current concentrates near the surface of the conductor and the inner portion carries less current than at low frequencies. These belong to the simplest class of single input, single output converters which use one inductor and one active switch. Acoustic noise Faint, usually inaudible mains hum, usually due to vibration of windings in the transformer or magnetostriction.
However, core losses increase at higher frequencies.
There are many variations and extensions to this class of converters but these three form the basis of almost all isolated and non-isolated DC to DC converters.
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