Update : December 25, 2023
Modern Insulated Gate Bipolar Transistors (IGBTs) are commonly utilized as voltage-controlled bipolar devices exhibiting metal-oxide-semiconductor (MOS) )-like input characteristics and bipolar output features. The advent of IGBTs has empowered electronics engineers to leverage the advantages of both Power MOS Field-Effect Transistors (MOSFETs) and small-signal Bipolar Transistors (BJTs) within a singular hardware unit, seamlessly amalgamating the functionalities of power MOSFETs and BJT components. This structural integration combines the straightforward gate-drive characteristics of MOSFETs with the high-current and low-saturation-voltage capabilities of bipolar transistors.
The term "insulated gate" pertains to the high input impedance of the MOSFET's input, utilizing the voltage at its gate terminal rather than an external supply. Simultaneously, the term "bipolar" characterizes the BJT's output region, where current flows through two charge carriers: electrons and holes. This dual-carrier characteristic enables the management of substantial currents and voltages with minimal signal voltage, rendering the IGBT a voltage-controlled device due to its hybrid construction.
IGBTs play a pivotal role in power electronics, particularly in applications such as Pulse Width Modulation (PWM) servo and three-phase drives that demand precise control over a broad range of speeds with minimal background noise. Their utility extends to power circuits requiring frequent switching, exemplified in Uninterruptible Power Supply (UPS) and Switched-Mode Power Supply (SMPS) systems. The incorporation of IGBTs enhances efficiency and reduces noise, positioning them as dynamic performers in inverter circuits for automobiles, trucks, industrial motors, and household appliances like air conditioners and refrigerators.
Moreover, IGBTs find prominent applications in renewable energy systems such as solar and wind power inverters. In these systems, IGBTs efficiently convert DC power into AC power for residential and commercial use, given their capability to handle high voltage and current levels. Their efficacy extends to resonant-mode converter circuits and induction cookers. Commercially available IGBTs are characterized by low switching and conduction losses.
Consider an example of an inductive heating circuit, where zero-voltage switching or zero-current switching is employed to minimize switching losses. IGBTs are preferred in such applications due to their capability to handle high resonance voltage or current. Induction microwave ovens, induction rice cookers, and other induction cooking appliances exemplify the versatility of IGBTs in this context. In UPS systems, IGBTs, available in both medium and large capacities, contribute to both space-saving and high efficiency.
Another notable application is in Voltage Source Converters (VSCs), where the high voltage and current ratings of IGBTs offer control and flexibility not achievable with thyristors. This enables the implementation of multiterminal DC lines, reducing the difficulty of filtering current harmonics on the AC side through the application of PWM and multilayer converter techniques. The relentless advancement of IGBTs facilitates the widespread adoption of HHigh-voltage(HVDC) transmission systems, making DC lines an appealing alternative for shorter grid segments due to their enhanced control over flow routes.
Conductivity modulation results in an extremely small on-state voltage drop and a high on-state current density, allowing for a reduction in chip size and cost.
The MOS gate input provides low driving power capability and a straightforward drive circuit, simplifying regulation in high-current and voltage applications.
IGBTs offer a large safe operating area, surpassing the bipolar transistor in conducting current and exhibiting superior forward and reverse blocking capabilities.
The internal PNPN-layered construction may lead to latch-up, where the gate loses control over the collector current.Turning off the IGBT requires forced commutation of the current, akin to a regular thyristor. Prolonged latch-up states can result in significant power dissipation and potential damage to the IGBT.
The switching speed is slower than a power MOSFET but faster than a BJT. The turnoff time is slow due to collector current tailing caused by minority carrier effects.
IGBTs, characterized by their voltage-controlled bipolar attributes with MOS-like input characteristics and bipolar output features, find extensive application in power electronics circuits, including inverters, UPS, VSCs, and inductive heating circuits. Commercially available IGBTs boast low switching and conduction losses, offering numerous advantages over BJT and MOSFET counterparts. These advantages include a small on-state voltage drop, high on-the-current density, low driving power requirement, simplified regulation, a large safe operating area, and superior forward and reverse blocking capabilities. Additionally, IGBTs exhibit fast-switching speeds and can handle high power levels, positioning them as ideal components for power electronics applications such as high-voltage DC (HVDC) transmission systems.
IGBT gate driver design, how to choose the key components
What is a Gate Driver?
