IGBT Bipolar Transistors are widely used in power electronics. They are reliable and inexpensive components that are controlled by energizing an isolated element from the circuit. IGBT is a transistor whose principle of operation is extremely simple. It is used in inverters, electric drive control systems and switching power supplies.
Content
- History of appearance
- Main characteristics
- Advantages and disadvantages
- Device and principle of operation
- Scope of use
- Serviceability check
- Powerful modules
History of appearance
The first field-effect transistors were developed in 1973, and after 6 years, controlled bipolar models appeared, in which an insulated gate was used. With the improvement of technology, the indicators of the efficiency and quality of work of such elements have significantly improved, and with the development of power electronics and automatic control systems, they have become widespread, found today in almost every electrical appliance.
Today electronic components of the second generation are used, which are capable of switching electric currents in the range of up to several hundred Amperes. The operating voltage of IGBT transistors ranges from hundreds to thousands of volts. Improving technologies for the manufacture of electrical engineering make it possible to produce high-quality transistors that ensure the stable operation of electrical appliances and power supplies.
Main characteristics
The principle of operation of transistors and their characteristics will directly depend on the type of device and its design. The main parameters of semiconductors include the following:
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Maximum allowable current. - Indicator of the control voltage.
- Internal resistance.
- Connection and disconnection delay period.
- Parasitic inductance.
- Input and output capacitance.
- Saturation voltage at emitter and collector.
- Emitter cutoff current.
- Collector and emitter breakdown voltage.
Powerful IGBT transistors, which are used in inverter power supplies, are widely used today. Such devices simultaneously combine power, high accuracy and a minimum of parasitic inductance. Speed controllers use IGBTs with a frequency of tens of thousands of kHz, which allows you to ensure the highest possible accuracy of the devices.
Advantages and disadvantages
Today on sale you can pick up various models of semiconductors, which will differ in their operating frequency, capacity and a number of other characteristics. The popularity of IGBT transistors is due to their excellent parameters., characteristics and numerous advantages:
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Possibility of operation with high power and increased voltage. - Work at high temperatures.
- Minimum open-circuit current losses.
- Short circuit resistance.
- Increased density.
- Almost complete absence of losses.
- Simple parallel circuit.
The disadvantages of IGBTs include their high cost, which leads to a slight increase in the cost of manufacturing electrical appliances and powerful power supplies. When planning a connection diagram with transistors of this type, it is necessary to take into account the existing limitations in terms of the maximum permissible current. To solve problems like this, you can use the following design solutions:
- Using a roundabout switching path.
- Choice of gate resistance.
- Correct selection of protection current indicators.
Wiring diagrams of devices should be developed exclusively by professionals, which will ensure the correct operation of equipment, the absence of short circuits and other problems with electrical appliances. If you have a high-quality connection diagram, it will not be difficult to implement it by making your own power unit, power supply and various devices.
Device and principle of operation
The internal structure of the IGBT transistor consists of two cascade electronic switches that control the final output. In each case, depending on the power and other indicators, the design of the device may vary, including additional shutters and other elements that improve power and allowable voltage indicators, ensuring the ability to operate at temperatures above 100 degrees.
IGBT type semiconductors have a standardized combined structure and the following designations:
- K - collector.
- E - emitter.
- З - shutter.
The principle of operation of the transistor is extremely simple. As soon as a positive potential voltage is applied to it, an n-channel opens in the gate and source of the field-effect transistor, resulting in the movement of charged electrons. This excites the action of the bipolar transistor, after which an electric current begins to flow from the emitter directly to the collector.
The main purpose of IGBT transistors is their approximation to the safe value of fault currents. These currents can limit the gate voltage in a variety of ways.
By binding to the set voltage indicator. The gate driver must have constant parameters, which is achieved by adding a Schottky diode to the device circuit. This ensures that the inductance in the power supply and the gate is reduced.
Voltage indicators are limited due to the presence of a zener diode in the emitter and gate circuit. The excellent efficiency of such IGBT transistors is achieved by installing additional diodes at the terminals of the module. The components used must have a high temperature independence and a small spread.
The circuit can include a negative feedback emitter. This is possible when the gate driver is connected to the module terminals.
The correct choice of the type of transistor will ensure the stability of the operation of power supplies and other electrical appliances. Only in this case, it is possible to guarantee the completely safe operation of electrical installations in case of short circuits and in emergency modes of operation of equipment.
Scope of use
Today IGBT transistors are used in networks with a voltage indicator up to 6.5 kW, while ensuring the safe and reliable operation of electrical equipment. It is possible to use an inverter, variable frequency drives, welding machines and pulse current regulators.
Heavy-duty IGBT varieties are used in powerful control drives for trolley buses and electric locomotives. Their use makes it possible to increase the efficiency, ensuring the maximum possible smoothness of the operation of the equipment, promptly controlling the output of electric motors to their full power. Power transistors are used in high voltage circuits. They are used in circuits for household air conditioners, dishwashers, power supplies in telecommunications equipment, and in automotive ignition.
Serviceability check
Revision and testing of IGBT semiconductors is carried out in the presence of faults in electrical devices. Such a check is carried out using a multitester, ringing the collectors and electrodes with an emitter in two directions. This will allow you to establish the operability of the transistor and eliminate the absence of a short circuit. When testing, it is necessary to negatively charge the gate input using COM type multimeter probes.
To check the correct operation of the transistor at the input and output of the gate, the capacitance is charged with a positive pole. Such charging is performed by briefly touching the shutter with the probe, after which the potential difference between the collector and emitter is checked. These potentials should not have a discrepancy of more than 1.5 Volts. If a powerful IGBT is being tested, and the tester is not enough for a positive charge, a supply voltage of up to 15 volts is applied to the gate.
Powerful modules
Power transistors are manufactured not only by individual semiconductors, but also by already assembled ready-to-use modules. Such devices are part of powerful frequency converters in the control of electric motors. In each case, the scheme and principle of operation of the module will differ depending on its type and purpose. Most often, such devices use a bridge made on the basis of two power transistors.
Stable operation of the IGBT is ensured at a frequency of 150 kHz. With an increase in the operating frequency, losses may increase, which negatively affects the stability of electrical appliances. Power transistors show all their advantages and capabilities when used with voltages over 400 volts. Therefore, such semiconductors are most often used in industrial equipment and high voltage electrical appliances.
