基于sg3525設(shè)計(jì)單相正弦波spwm逆變電源外文翻譯-文庫(kù)吧資料
2024-09-01 14:21本頁(yè)面
【正文】 e voltage. Most small aircraft use 28 V DC, but larger aircraft like Boeing747 often use up to 90 kVA 3phase at 200 V AC 400 Hz, though they often have a DC bus as well. Even fighter planes like F16 use 400 Hz power. The MD81 airplane has an 115/200 V 400 Hz AC and 28 V DC power system generated by three 40 kVA AC generators. Helicopters also use the 28 V DC system. Some submarines like the Soviet Alfa class submarine utilized two synchronous generators providing a variable threephase current, 2 x 1500 kW, 400 V, 400 Hz. The space shuttle uses three fuel cells generating 30 36 V DC. Some is converted into 400 Hz AC power and 28 V DC power. The International Space Station uses 120 V DC power. Larger trucks uses 24 V DC.See also: Avionics, Airplane ground supportIn the case of TV sets, for example, one can test the excellent regulation of the power supply by using a variac. For example, in some models made by Philips, the power supply starts when the voltage reaches around 90 volts. From there, one can change the voltage with the variac, and go as low as 40 volts and as high as 260 (known such case that voltage was 360), and the image will show absolutely no alterations.TerminologyThe term switchmode was widely used until Motorola trademarked SWITCHMODE(TM), for products aimed at the switchingmode power supply market, and started to enforce their trademark. 外文翻譯開(kāi)關(guān)模式電源開(kāi)關(guān)模式電源（也開(kāi)關(guān)式電源，開(kāi)關(guān)電源，或只是交換機(jī)）是一種電子電源供應(yīng)器（電源），包含了開(kāi)關(guān)穩(wěn)壓器。 pared 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, ponents with lower capacitance and inductance are needed. Simpler, nonisolated power supplies contain an inductor instead of a transformer. This type includes boost converters, buck converters, and the so called buckboost converters. These belong to the simplest class of single input, single output converters which utilize 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. For example an ideal buck converter with a 10 V input operating at a 50% duty cycle will produce an average output voltage of 5 V. A feedback control loop is employed to regulate the output voltage by varying the duty cycle to pensate for variations in input voltage. The output voltage of a boost converter is always greater than the input voltage and the buckboost 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 nonisolated DC to DC converters. By adding a second inductor the ?uk and SEPIC converters can be implemented, or, by adding additional active switches, various bridge converters can be realised. Other types of SMPSs use a capacitordiode voltage multiplier instead of inductors and transformers. These are mostly used for generating high voltages at low currents (CockcroftWalton generator). The low voltage variant is called charge pump.RegulationA feedback circuit monitors the output voltage and pares it with a reference voltage, which is set manually or electronically to the desired output. If there is an error in the output voltage, the feedback circuit pensates by adjusting the timing with which the MOSFETs are switched on and off. This part of the power supply is called the switching regulator. The Chopper controller shown in the block diagram serves this purpose. Depending on design/safety requirements, the controller may or may not contain an isolation mechanism (such as optocouplers) to isolate it from the DC output. Switching supplies in puters, TVs and VCRs have these optocouplers to tightly co
畢業(yè)設(shè)計(jì)相關(guān)推薦
鄂ICP備17016276號(hào)-1