Electronic equipment, particularly computers have been miniaturized power supply required volume along with miniaturization, and therefore began to replace the power switch to light the frequency characteristics of the linear transformer power supply, and power efficiency has been significantly improved. Reduce the power dissipation capability volume means worse, thus requiring smaller power consumption, that is, under the premise of constant output power, efficiency must be improved.
High efficiency power conversion: Subject to pursue switching power supply design
Similar volume of supply of power dissipation base really the same, therefore, want to get more output power, it is necessary to improve the efficiency and high power efficiency can effectively reduce the stress of power semiconductor devices, help to improve its reliability.
Switching power loss is important: loss of passive components and active components loss
Switching losses have been wondering the switching power supply designers, because power semiconductor devices in the switching process, while the presence of the device current, voltage, and therefore inevitably switching losses, if the switching power supply switch and output rectifier diodes to achieve zero-voltage switching or zero current switching, its efficiency can be significantly improved.
Switching losses caused by the switching process will total roughly 5% to 10% of the input power to significantly reduce or eliminate this loss can improve the efficiency of 5% to 10% of the switching power supply. The most effective way is to soft-switching technology or zero voltage switching or zero-current switching technology.
Among the many soft-switching scheme, there is a practical comparison of full-bridge power converter, usually taken phase zero voltage switching control method, this control method requires an additional demand on the primary side inductance in order to ensure continued flow switch in zero-voltage turn-on state, because the larger the effective value of current flowing through the inductor will add heat (although smaller than the RC snubber circuit), and therefore does not take the low-voltage power.
Passive lossless snubbed circuit characteristics are not damaged Orders PWM control methods, design / debug simple. Nevertheless, passive lossless snubbed circuit and quasi-resonant / zero voltage switching methods of work, there are some disadvantages, such as can only achieve soft switching off and flyback converters quite suitable for a large range of load changes. Soft active clamp switch is to improve the single-tube forward / flyback converter efficiency and effective method, the initial patent restrictions now lapsed, can be widely applied.
Power semiconductor devices Increase
Increase the power semiconductor devices in particular raise a series of initiators PowerMOSFET improve power conversion: PowerMOSFET the fast switching speed, so that the Etekcity 2 Pack Wireless Socket Outlet Switches frequency of the switching power supply was increased from 20kHz to 100kHz bipolar transistor more effectively reduces passive energy storage components (inductors, capacitors) volume. Low pressure low PowerMOSFET reality synchronous rectification device from the ON voltage of the Schottky diode is about 0.5V, 0.1V synchronous rectifier to reduce or even lower, so that the efficiency of the low pressure rectifier, at least a 10% improvement. High pressure drop PowerMOSFET improves the conduction and switching characteristics, improve the efficiency of the primary switching power supply. Reduction in power consumption of the power semiconductor device and the radiator is the volume of the machine is reduced.
Efficiency at the same time: the power supply has been reduced electromagnetic interference
In a variety of switching power loss, the loss of electromagnetic interference generated by the high power efficiency to the degree of certainty will not be ignored. On the one hand electromagnetic interference itself consumes energy, especially the power efficiency often need soft-switching technology or zero voltage switching or zero-current switching technology (whether inherent specifically set or circuit), the application of these techniques to slow the process of switching voltage, current, the rate of change or remove the switching process, electromagnetic interference becomes very small, like a general rule does not require switching power supply circuit must specifically set electromagnetic interference suppression circuit (this circuit is present losses).
Switching power supply into: high efficiency power conversion period
Careful analysis of high-efficiency power conversion seems to be very simple, even some circuit topologies have introduced over 20 years ago (such as two-stage conversion topology, as early ApplicationNote of AN19 UNITRODE82/83 years have introduced in the data sheet, TEK2235 oscilloscopes have taken this power conversion topology), but subject to the prior level of technology, in particular restrictions awareness (that is always lower than the conversion efficiency of two-stage single-stage, two-stage transformation may be achieved and in fact the fact inherent to the zero voltage switch, in particular a single-stage conversion of the required additional circuitry and control methods) and the admission has not been applied. Performance and increase in awareness of the device has made the two-stage transformation as an important method of high efficiency power conversion.