26 Aug What is the use of IGBT in induction cooker?
Features of IGBT tube
The Iusulated Gate Bipolar Transistor (IGBT) is a high-voltage, high-speed, high-power device that combines the large current density of a BJT and the advantages of a MOSFET voltage-excited field-controlled device.
There are IGBT tubes made from different materials and processes; they can be considered a composite structure with a MOSFET input followed by a bipolar transistor for amplification.
IGBT tubes have three electrodes, called gate G
(also called control or gate), collector C (also called a drain), and emitter E (also called source).
The IGBT tube overcomes a fatal flaw of the power MOSFET: high on-resistance, severe heat generation, and reduced output efficiency when operating at high voltage and high current.
The IGBT tube is a field-effect transistor with an additional P-layer between the drain and the drain regions.
According to IEC/TC (CO) 1339, the names of its parts follow the corresponding nomenclature of field-effect transistors.
The IGBT tube has both the high-speed switching and voltage driving characteristics of a power MOSFET and the low saturation, voltage characteristics of bipolar transistors,
and the ability to quickly achieve higher currents.
The IGBT is one of the most exciting and fastest-growing devices in power electronics in recent years.
IGBT tube is the composite device, which integrates power MOSFET and GTR in one chip. Power MOSFET is a unipolar voltage drive device, which has fast working speed, high input impedance, good thermal stability and drive.
The circuit is simple and has other characteristics, but its on-resistance is large, and the current capacity is also relatively large and low. The GTR is a bipolar current drive device with high blocking voltage and high load.
Current solid capacity, but slower working speed, sizeable driving current, and more control circuit complex. The shortcomings of these two types of devices limit their development. Currently appearing Many new composite devices, such as MOS bipolar composite transistor, MOS Bipolar composite thyristors, these new power electronic composite devices, are a collection of The advantages of unipolar and bipolar devices.
Power MOSFETs require a high breakdown voltage because achieving a high breakdown voltage requires a source-drain channel with high resistivity, resulting in a high RDS(on) value power MOSFET.
Resulting in a power MOSFET with a high RDS(on) value. Although the latest
generation power MOSFET devices have significantly improved the RDS(on) characteristics, the
Although the latest generation of power MOSFET devices has significantly improved the RDS(on) characteristics, the power conduction loss at high levels is still much higher than that of IGBT tubes.
The structure of the IGBT tube supports higher current densities and simplifies the driver compared to the same standard bipolar device.
The IGBT tube structure supports higher current density and simplifies the driver circuitry.
IGBT tubes are rapidly developing, and this composite device belongs to the transistor class, which can be used as both a switch and an amplifier.
It can be used both as a switch and as an amplifier and has good characteristics that make it
It is suitable for medium frequency power supply.
IGBT tube is a perfect device. It has outstanding conduction characteristics and many characteristics of the power MOSFET, such as easy to drive, easy to drive, wide safe working area, high peak current, rugged, etc. Generally speaking, the switching speed of IGBT tubes is lower than that of power MOSFETs, but IR's.
The switching characteristics of the new series of IGBT tubes are very close to those of power MOSFETs, and the on-state characteristics are not affected by the operating voltage.
The on-state characteristics are not affected by the operating voltage. Since IGBT tubes do not have internal.
IGBT tubes do not have a reverse diode, and the application can be flexible to use external recovery diodes.
This feature is an advantage or disadvantage that should consider. Whether this feature is an advantage or a disadvantage should be determined by the operating frequency, diode price and current capacity.
The price and current capacity of the diode are the parameters to be measured.
Structure of IGBT tube
IGBT tubes are similar in structure to MOSFETs but differ because IGBT is an N+ base plate (drain) of N-channel power MOSFET.
A P+ base plate (collector of the IGBT tube) is added to the N+ base plate (drain) of the N-channel power MOSFET to form a PN junction J1, and The gate and source are utterly similar to MOSFETs.
The structure of the IGBT is shown in Figure 1. It is because the IGBT tube is on the N+ substrate of the N-channel MOSFET.
N-channel MOSFET with a P+ base plate, forming a four-layer
structure, the PNP-NPN type transistors form the IGBT tube. However, the NPN transistors are shorted between the emitter and the aluminum electrode.
The NPN transistor is designed to be inactive. Therefore, the essential operation of IGBT tubes is similar to that of NPN transistors.
The essential operation of the IGBT tube is not related to the NPN transistor, and it can be considered the N-channel.
MOSFET as the input terminal and PNP transistor as the output terminal of Darlington tube.
The working principle of IGBT tube
The N-channel IGBT tube creates a (positive) voltage across the P-layer directly below the gate by adding a threshold voltage UTH between the gate and the emitter.
(positive) voltage above the voltage UTH, the P-layer directly below the gate forms
The inverse layer (channel) begins to inject electrons from the N-layer under the emitter. The
electrons are the minority carriers of the PNP-type transistor and start to flow into the holes from the collector substrate P+ starts to flow into the hole for conductivity modulation (bipolar operation), so it is possible to decrease.
The IGBT tube operates with an equivalent circuit, as shown in Figure 2 (a).
The equivalent circuit for IGBT tube operation is shown in Figure 2(a). The graphical symbols are shown in Figure 2(b). The NPN-type parasitic transistor is formed on the emitter side, and if the NPN-type parasitic transistor works, it becomes a quadruple structure thyristor again. The current continues to flow until the output side stops supplying current, at which point the output signal is no longer available for control through the output signal. This state is generally referred to as a latching state.
For suppressing the operation of NPN-type parasitic transistors, IGBT tubes use the method of minimizing the current amplification factor α of PNP-type transistors as a measure to solve the blocking. As a measure to solve the blocking. Specifically, the current amplification factor α of PNP transistors is designed to be 0.5 or less. The current blocking IL of the IGBT tube is three times the rated current (DC). The blocking current of the IGBT tube is more than three times the rated current (DC).
The main parameters of IGBT tube
The maximum allowable values of current, voltage, power, etc., that an IGBT tube can withstand are generally defined as the maximum ratings. When designing a circuit, correctly understand and identify the maximum ratings is particularly important for the reliable operation and ultimate service life of the IGBT tube.
- The short-circuit current of the IGBT tube can be more than ten times the rated current, and the value of short-circuit current is determined by the gate voltage and transconductance of the IGBT tube. Correct control of the short-circuit current of IGBT tubes is a necessary guarantee for the reliable operation of IGBT tubes.
(2) Shutdown characteristics of inductive load.
When the IGBT tube is shut down, the voltage will rise from several volts to supply voltage instantaneously (during this period, the on-state current remains unchanged), and resulting in considerable voltage stress du/DT, which will seriously threaten the reliability of the IGBT tube in long-term operation. In the circuit design, the du/dt at turn-off can be limited and reduced by adding resistors to the gate drive circuit.
(3) Maximum gate emitter voltage (UGE).
The gate voltage is determined by the thickness and characteristics of the gate oxide layer. The breakdown voltage of the gate to emitter is generally 80 V. The gate voltage is usually limited to 20 V or less To ensure their safety.
(4) gate input capacitance.
IGBT tube input capacitance characteristics directly affect the reliability of the gate drive circuit design. IGBT tube as a general conductive device, the switching characteristics are affected by the general injection and compound and gate drive conditions. In practice, taking into account the miller effect of capacitance, the drive capability of the gate drive circuit should be greater than 2 to 3 times the value specified in the manual.
(5) Safe operating area characteristics.
The device works in the high current and high voltage switching state due to the uneven current distribution when the safe operating limit is exceeded, often causing damage to the device. The current distribution is related to the di/dt so that the safe working area is often divided into the forward safe working area and the reverse safe working area.
Applications
- Induction Cooking Stoves
- Inverterized Microwave Ovens
- Induction Rice Cookers
- Induction Water Heaters
- Other resonant switching topologies
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