Overview: Power Semiconductor Devices

A semiconductor device used as a switch or rectifier in power electronics; a switch-mode power supply is an example. Such a device is also called a power device or, when used in an integrated circuit, a power IC. A power semiconductor device is usually used in "commutation mode" (i.e., it is either on or off), and therefore has a design optimized for such usage; it should usually not be used in linear operation.

History

The first power semiconductor device appeared in 1952 with the introduction of the power diode by R.N. Hall. It was made of Germanium and had a voltage capability of 200 V and a current rating of 35 A.

The thyristor appeared in 1957. It is able to withstand very high reverse breakdown voltage and is also capable of carrying high current. However, one disadvantage of the thyristor in switching circuits is that once it becomes 'latched-on' in the conducting state; it cannot be turned off by external control, as the thyristor turn-off is passive, i.e., the power must be disconnected from the device.

The first bipolar transistor device with substantial power handling capabilities was introduced in the 1960s. This component overcomes some limitations of the thyristor, because it can be turned on or off with an applied signal.

Due to improvements in the MOSFET technology (metal oxide semiconductor technology, initially developed to produce integrated circuits), the power MOSFET became available in the late 1970s. International Rectifier introduced a 25 A, 400 V power MOSFET in 1978.[1] This device allows operation at higher frequencies than a bipolar transistor, but is limited to low voltage applications.

The Insulated-gate bipolar transistor (IGBT) was developed in the 1980s, and became widely available in the 1990s. This component has the power handling capability of the bipolar transistor and the advantages of the isolated gate drive of the power MOSFET.

Common devices

Some common power devices are the power diode, thyristor, power MOSFET, and IGBT. The power diode and power MOSFET operate on similar principles to their low-power counterparts, but are able to carry a larger amount of current and are typically able to support a larger reverse-bias voltage in the off-state.

Structural changes are often made in a power device in order to accommodate the higher current density, higher power dissipation, and/or higher reverse breakdown voltage. The vast majority of the discrete (i.e., non-integrated) power devices are built using a vertical structure, whereas small-signal devices employ a lateral structure. With the vertical structure, the current rating of the device is proportional to its area, and the voltage blocking capability is achieved in the height of the die. With this structure, one of the connections of the device is located on the bottom of the semiconductor die.

Classifications

Fig. 1: The power devices family, showing the principal power switches.

A power device may be classified as one of the following main categories (see figure 1):

• A two-terminal device (e.g., a diode), whose state is completely dependent on the external power circuit to which it is connected.
• A three-terminal device (e.g., a triode), whose state is dependent on not only its external power circuit, but also the signal on its driving terminal (this terminal is known as the gate or base).

Another classification is less obvious, but has a strong influence on device performance:

• A majority carrier device (e.g., a Schottky diode, a MOSFET, etc.); this uses only one type of charge carriers.
• A minority carrier device (e.g., a thyristor, a bipolar transistor, an IGBT, etc.); this uses both majority and minority carriers (i.e., electrons and electron holes).
• A majority carrier device is faster, but the charge injection of minority carrier devices allows for better on-state performance.

Diodes

An ideal diode should have the following characteristics:

• When forward-biased, the voltage across the end terminals of the diode should be zero, whatever the current that flows through it (on-state).
• When reverse-biased, the leakage current should be zero, whatever the voltage (off-state).
• The transition (or commutation) between the on-state and the off-state should be instantaneous.
• In reality, the design of a diode is a trade-off between performance in on-state, off-state, and commutation. Indeed, the same area of the device must sustain the blocking voltage in the off-state and allow current flow in the on-state; as the requirements for the two states are completely opposite, a diode has to be either optimized for one of them, or time must be allowed to switch from one state to the other (i.e., the commutation speed must be reduced).
• These trade-offs are the same for all power devices; for instance, a Schottky diode has excellent switching speed and on-state performance, but a high level of leakage current in the off-state. On the other hand, a PIN diode is commercially available in different commutation speeds (what are called "fast" and "ultrafast" rectifiers), but any increase in speed is necessarily associated with a lower performance in the on-state.

Switches

The trade-offs between voltage, current, and frequency ratings also exist for a switch. In fact, any power semiconductor relies on a PIN diode structure in order to sustain voltage; this can be seen in figure 2. The power MOSFET has the advantages of a majority carrier device, so it can achieve a very high operating frequency, but it cannot be used with high voltages; as it is a physical limit, no improvement is expected in the design of silicon MOSFET concerning its maximum voltage ratings. However, its excellent performance in low voltage applications make it the device of choice (actually the only choice, currently) for applications with voltages below 200 V. By placing several devices in parallel, it is possible to increase the current rating of a switch. The MOSFET is particularly suited to this configuration, because its positive thermal coefficient of resistance tends to result in a balance of current between the individual devices.

The IGBT is a recent component, so its performance improves regularly as technology evolves. It has already completely replaced the bipolar transistor in power applications; a power module is available in which several IGBT devices are connected in parallel, making it attractive for power levels up to several megawatts, which pushes further the limit at which thyristors and GTOs become the only option. Basically, an IGBT is a bipolar transistor driven by a power MOSFET; it has the advantages of being a minority carrier device (good performance in the on-state, even for high voltage devices), with the high input impedance of a MOSFET (it can be driven on or off with a very low amount of power).

The major limitation of the IGBT for low voltage applications is the high voltage drop it exhibits in the on-state (2-to-4 V). Compared to the MOSFET, the operating frequency of the IGBT is relatively low (usually not higher than 50 kHz), mainly because of a problem during turn-off known as current-tail: The slow decay of the conduction current during turn-off results from a slow recombination of a large number of carriers that flood the thick 'drift' region of the IGBT during conduction. The net result is that the turn-off switching loss of an IGBT is considerably higher than its turn-on loss. Generally, in datasheets, turn-off energy is mentioned as a measured parameter; that number has to be multiplied with the switching frequency of the intended application in order to estimate the turn-off loss.

At very high power levels, a thyristor-based device (e.g., a SCR, a GTO, a MCT, etc.) is still the only choice. This device can be turned on by a pulse provided by a driving circuit, but cannot be turned off by removing the pulse. A thyristor turns off as soon as no more current flows through it; this happens automatically in an alternating current system on each cycle, or requires a circuit with the means to divert current around the device. Both MCTs and GTOs have been developed to overcome this limitation, and are widely used in power distribution applications.

Diodes
Description

Diode Modules include one or more power diodes and, in some cases, other power semiconductor devices. Diode module packages are electrically isolated, and usually include metal base-plates (sometimes copper) and a DCB Alumina substrate (Al2O3 Insulator). Power Semiconductor Diode Modules have high thermal efficiency, which assures long life and reliable performance. These modules come with voltage ratings typically between 200 – 1,600 volts (available up to 6,500 volts) and current ratings from 10 – 2,500 amps. Many of these Diode Modules are UL Recognized and RoHS-compliant.

Applications

• Bridge Circuits (single-phase and three-phase),
• AC-DC Motor Drives
• Battery Chargers
• Power Supplies
• Large IGBT Front End Circuits
• Lighting Control
• Heat/Temperature Controls (for large commercial ovens, chemical processes, etc.)
• Motor Drives and Industrial Welders

Specific attributes

• Configuration – 3 Phase Bridge Rectifier, Antiparallel Pair (unconnected), Diode Phase Leg, Dual Parallel Diodes, Dual Common Anode, etc. (many more configurations available)
• Voltage Rating (V)
• Current Rating (A)
• Package Type

Manufacturers

We offer diode modules from Germany IXYS, Eupec, Semikron, Japan Sanrex, Mitsubishi, NIEC, and the U.S. IR

FRD – Fast Recovery Diode
Description

High-voltage and high-current diodes contributing to low loss and downsizing
FRD (Fast Recovery Diode) is the advent of a new type of semiconductor devices in recent years, with good switching characteristics, reverse recovery time is short, forward current, small size, easy to install and so on. Ultrafast recovery diode SRD (Superfast Recovery Diode), is based on the fast recovery diode evolved, the reverse recovery time value is close to the Schottky diode indicators. They can be widely used in switching Power supply, pulse width modulator (PWM), uninterruptible power supply (UPS), AC Motor Variable Speed (VVVF), high-frequency heating device for high-frequency, high current diode or rectifier, is very promising electrical, electronic semiconductor devices.

Features

• Low VF
• Ultrafast recovery time
• High reliability and low leakage current
• Abundant product lineup with various packages

Applications

• Home electrical appliance
• OA equipment
• Motor equipment
• Industrial equipment

Manufacturers

We offer FRD from Germany IXYS, Eupec, Semikron, Japan Sanrex, Mitsubishi, Motorola, Hitachi, Fuji, Renesas and the U.S. IR

GTR- Giant Transistor
Description

GTR Module is of high quality and it finds wide applications in many industries like engineering, electronic and IT sectors. GTR Module is highly known for their reliability and high performance. It is easy to maintain and can be availed at the cost effective prices. In electronics field, GTR has the features of fast switching speed, simple driving circuit and low device cost. Therefore, it can replace the transistor in medium and small power AC speed regulation, inversion and chopping wave. Because of its simple design and convenient maintenance, it is favored in the electronics industry.

Structure

The structure and working principle of GTR are very similar to small power transistors. It consists of three layers semiconductor, two PN junctions. And the same as the little power, it has NPN and PNP two types, the GTR usually uses NPN structure.

Features

Output voltage
It can use PWM mode, the output voltage is strong pulse sequence with its amplitude equals to the DC voltage.

Carrier frequency
The allowed carrier frequency is low, most of the upper limit of the carrier frequency inverter is about 1.2 ~ 1.5 kHz.

Current waveform
Because the carrier frequency is low, so the current ultraharmonic component is bigger. These ultraharmonic current will form eddy in the silicon steel, and electric magnetic force is produced, thus to produce noise.

Output torque

Because of the high ultraharmonics current composition, in 50 Hz, the output torque will be decreased compared with industrial frequency operation.

Manufacturers

The GTR we offered mainly from Japan Fuji, Mitsubishi, Toshiba, Sanken, Sanrex and Germany Eupec, IXYS etc.

IGBT – Insulated Gate Bipolar Transistor
Description

IGBT modules consist of many devices in parallel and can have very high current handling capabilities in the order of hundreds of amperes with blocking voltages of 6000 V, equating to hundreds of kilowatts. Rather than using a device physics-based model, SPICE simulates IGBTs using Macromodels, a method that combines an ensemble of components such as FETs and BJTs in a Darlington configuration. An alternative physics-based model is the Hefner model, introduced by Allen Hefner of the NIST. It is a fairly complex model that has shown very good results. Hefner's model is described in a 1988 paper and was later extended to a thermo-electrical model and a version using SABER.

Components

IGBT module is mainly composed by IGBT chip, diode chip, DBC, aluminum wire, Silicone gel, and electrode.

Application

IGBT module is the advanced third generation power module, with working frequency from 1-20 KHZ. It is mainly applied in the main circuit inverter of the transducer and all inverter circuits, namely the DC/AC conversion, such as electric vehicles and servo controller, UPS, switch power supply, chopping power supply, trolley buses, etc.

Features

IGBT module has the features of large input impedance, less drive power and simple control circuit, small switch loss, fast break speed, high working frequency, and large capacity. Indeed, it is a composite power component, integrating the advantages of bipolar type power transistors and power MOSFET. The development trend of IGBT module is high voltage, large current, high speed, low pressure drop, high reliability and low cost, especially the development of the high voltage inverter application. It aims to simplify the main circuit and debugging, reduce using devices and the manufacturing cost, and improve reliability.

Manufacturers

The IGBT MODULE we offered mainly from Germany Semikron, IXYS, Infineon, Japan Mitsubishi, Fuji, Sanken, Hitachi, Toshiba , and Switzerland ABB.

IPM /PMI - Intelligent Power Module
Description

Power module is the power supply can be directly mounted on PCB, which can provide power supply for Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Microprocessors , memory, Field Programmable Gate Array (FPGA ) and other digital or analog load power.

Application

In general, these modules are called point of load (POL) power supply system or the point of use power supply system (PUPS). As power modules have many advantages, so it is widely used in switching equipment, access equipment, mobile communications, microwave communication and optical transmission, routers and other communications and automotive electronics, aerospace and so on.

Manufacturers

We offer power modules from Germany Semikron, and Japan Ericson etc.

MOSFET - Power Mosfet Modules

• Applications
• Chopper
• Forklifts
• Off-Road Electric Vehicles
• Power Supplies
• UPS
• Low voltage high power application

Structure

• Circuit Configurations:
• Chopper (By Paralleling Legs)
• Dual (By Paralleling Legs)
• 6-Pac

Features

• Low VDS and Low VSD. Advanced 0.35mm MOSFET Chip Applied
• Snubber less. Guarantee of avalanche capability at Turn-off & Recovery
• Thermal sensor included
• Unit Size reduction & Easy for assembly. 6in1 compact package (FWDi chips are not necessary) Signal (gate and emitter) and thermal sensor connector

Manufacturers

We offer MOSFET modules from Germany IXYS, Siemens, Semikron, and Japan Mitsubishi, Fuji

SCR- Silicon Controlled Rectifier

Description

Silicon controlled module is usually called power semiconductor module. In 1970, Semikron first introduced module principle into power electronic technology field. It is the high-power semiconductor devices which adopt module packaging and it has three PN junctions, four layers.

Advantages

Small volume, light weight, compact structure, high reliability, and simple outside wiring, good interchangeability, convenient in maintenance and installation;

Well structure repeatability, mechanical design of the device can be simplified; price is lower than discrete device.

Because of these advantages, it is favored by the major power semiconductor manufacturers, and therefore got rapid development.

Classification

According to X chip, SCR module can be divided into controlled module and rectifier module. According to specific purposes, it can be divided into MTC \ MTX, MDC, common SCR, MFC, rapid SCR, MKC \ MZC, non-insulated SCR, MTG \ MDG, MDS and single phase (three-phase) rectifier bridge (MDQ), MTS and the Schottky module.

Features

• AC Load Control
• Floating point control
• 2-stage control
• Zero cross technology
• LED status display
• Snap-track mounted

Manufacturers

We offer SCR modules from Germany IXYS, Semikron, Eupec, the U.S. IR, Japan Sanrex, Mitsubishi

Thyristor Description

In its most basic form, a thyristor is a solid-state power semiconductor device with four alternating layers of P-type and N-type semiconductor material. A thyristor acts as a bistable switch, conducting (i.e. turning-on) when its gate receives a current pulse. A thyristor continues to conduct as long as it is forward-biased (until the voltage across the device is reversed). Thyristors are synonymous with silicon controlled rectifiers (SCRs).

Thyristor Modules include one or more thyristors and, in some cases, other power semiconductor devices, such as diodes. Thyristor module packages are electrically isolated, and usually include metal base-plates (sometimes copper) and a DCB Alumina substrate (Al2O3 Insulator). Thyristors can cycle an amazing amount of power, with voltage ratings typically between 300 – 2,400 volts and current ratings from 25 – 3,080 amps. Most Thyristor Modules are UL Recognized.

Applications

• Bridge Circuits
• AC Motor Drives
• DC Braking
• Battery Chargers
• Power Supplies
• Large IGBT Front End Circuits
• Lighting Control
• Heat/Temperature Controls (for large commercial ovens, chemical processes, etc.), and Welders

Specific attributes

• Configuration - Single, Dual, AC Switch, Anti-Parallel Pair, Pair Common Anode, Phase Leg (Series Pair), Dual Anti-Parallel Pair, Triple Anti-Parallel Pair, 3-phase Bridge Rectifier +Series Thyristor, and many more configurations available
• Voltage Rating (V)
• Current Rating (A)
• Package Type

Manufacturers

We offer thyristor modules from Germany IXYS, Semikron, Japan Mitsubishi and Taiwan MTK

Transistor Modules

The transistor module is an integrated device combined by multi-power transistors and its affiliated circuits. It is used in the main circuit of power electronics device. All kinds of electronic devices often need multi-interconnected power transistors, diodes and drive circuit to work together. Although these devices lines are various, the main circuit type is relatively fixed, thus it is possible to pack main circuit components and part of or the whole parts in a module according to the different types.

By adopting the transistor module, the power electronic circuit simplified components packaging, circuit connection and cooling system, reduced the impedance and coupling of the distribution parameters, thus minimized the device size, improved the performance and reliability as well as reduced the cost. The modularization of power transistors is one of the main directions for the electric power electronics device and line development. When the module is in use, the damage of some components of the device often causes the whole device failure.