81 inverter overview an inverter is a power converter

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Unformatted text preview: 1 Inverter Overview An inverter is a power converter that converts DC power to AC power. In stand-alone power systems, inverters are commonly used to convert DC from the storage battery to grid quality AC. This allows the use of domestic appliances such as televisions, stereos, power tools etc in off grid areas. Inverters are also used to produce grid compatible AC (stable voltage and frequency) from the rectified variable frequency and voltage of variable speed AC generators. Figure 8-1 Examples of grid connect inverters from Xantrex Technology, a leading manufacturer of power converters Figure 8-1 Examples of grid connect inverters from Xantrex Technology, a leading manufacturer of power converters ......................................................................................................................................................2 Figure 8-2 Schematic for a current source inverter for a permanent magnet synchronous motor ......................3 Figure 8-3 Schematic for a voltage source inverter for a permanent magnet synchronous motor ......................3 Figure 8-4 Generation of a pulse width modulated (PWM) waveform...............................................................4 Figure 8-5 Schematic of circuitry showing silicon-controlled rectifiers (SCR’s) using for soft-starting (one phase shown only).........................................................................................................................................5 Figure 8-6 Schematic of an inverter system used in variable speed, grid connected, turbine.............................6 Figure 8-7 Schematic of the Static Kraemer slip recovery system......................................................................7 Figure 8-8 Schematic of the double fed asynchronous generator (DFAG) .........................................................8 Figure 8-9 The 25kVA power converter used in conjunction with a 20kW synchronous generator wind turbine at MUERI..........................................................................................................................................9 Figure 8-10 Block diagram of series regulation controller................................................................................12 8-1 8-2 Early inverters, called rotary inverters, used a DC motor coupled to an AC generator to convert DC to AC. Even though this method is very reliable these devices were inherently inefficient and expensive, hence are now seldom used. Modern electronic inverters use a control circuit to rapidly switch semiconductor devices such as bipolar transistors (BTs) or field-effect transistors (FETs) to synthesise an AC waveform. Electronic inverters may be divided into two main classes: voltage source inverters or current source inverters. Current source (or current fed) inverters are those where the DC current is held constant and the voltage is varied to satisfy the load. To achieve this the inverter current is supplied through a large inductor on the DC link. Fig...
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This note was uploaded on 06/09/2011 for the course PV 5053 taught by Professor Aasd during the Three '11 term at University of New South Wales.

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