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IGBT is oftenly used in many modern appliances: (VFDs), electric trains, variable speed refrigerators, air-conditioners and even stereo systems with switching amplifiers. Since it is designed to turn on and off rapidly, Amplifiers that use it often synthesize complex waveforms with PWM and low pass filters.
The insulated-gate bipolar transistor or IGBT is a three-terminal power semiconductor device primarily forming an electronic switch and in newer devices is noted for combining high efficiency and fast switching The IGBT is suitable for many applications in power electronics, especially in Pulse Width Modulated (PWM) servo and three-phase drives requiring high dynamic rangecontrol and low noise. It also can be used in Uninterruptible Power Supplies (UPS),Switched-Mode Power Supplies (SMPS), and other power circuits requiring high switchrepetition rates.
The variable frequency drive controller is a solid state power electronics conversion system consisting of three distinct sub-systems: arectifier bridge converter, a direct current (DC) link, and an inverter. Voltage-source inverter (VSI) drives (see 'Generic topologies' sub-section below) are by far the most common type of drives. Most drives are AC-AC drives in that they convert AC line input to AC inverter output. However, in some applications such as common DC bus or solar applications, drives are configured as DC-AC drives. The most basic rectifier converter for the VSI drive is configured as a three-phase, six-pulse, full-wave diode bridge. In a VSI drive, the DC link consists of a capacitor which smooths out the converter's DC output ripple and provides a stiff input to the inverter. This filtered DC voltage is converted to quasi-sinusoidal AC voltage output using the inverter's active switching elements.
Controller advances have exploited dramatic increases in the voltage and current ratings and switching frequency of solid state power devices over the past six decades. Introduced in1983,[8] the insulated-gate bipolar transistor (IGBT) has in the past two decades come to dominate VFDs as an inverter switching device
In variable-torque applications suited for Volts per Hertz (V/Hz) drive control, AC motor characteristics require that the voltage magnitude of the inverter's output to the motor be adjusted to match the required load torque in a linear V/Hz relationship. For example, for460 volt,60 Hz motors this linear V/Hz relationship is460/60 =7.67 V/Hz. While suitable in wide ranging applications, V/Hz control is sub-optimal in high performance applications involving low speed or demanding, dynamic speed regulation, positioning and reversing load requirements. Some V/Hz control drives can also operate in quadratic V/Hz mode or can even be programmed to suit special multi-point V/Hz paths
