Showing papers on "Insulated-gate bipolar transistor published in 1994"

Utilization of an active-clamp circuit to achieve soft switching in flyback converters

Abstract: Flyback derived power convertor topologies are attractive because of their relative simplicity when compared with other topologies used in low power applications. Incorporation of active-clamp circuitry into the flyback topology serves to recycle transformer leakage energy while minimizing switch voltage stress. The addition of the active-clamp circuit also provides a mechanism for achieving zero-voltage-switching (ZVS) of both the primary and auxiliary switches. ZVS also limits the turn-off di/dt of the output rectifier, reducing rectifier switching losses, and switching noise due to diode reverse recovery. This paper analyzes the behavior of the ZVS active-clamp flyback operating with unidirectional magnetizing current and presents design equations based on this analysis. Experimental results are then given for a 500 W prototype circuit illustrating the soft-switching characteristics and improved efficiency of the power converter. Results from the application of the active-clamp circuit as a low-loss turn-off snubber for IGBT switches is also presented.

Zero-voltage and zero-current-switching full bridge PWM converter for high power applications

Abstract: A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulse-width modulated (PWM) converter is proposed. The new converter overcomes the limitations of the zero-voltage-switching (ZVS)-FB-PWM converter, such as high circulating energy, loss of duty cycle, and limited ZVS load range for the lagging-leg switches. By using the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the lagging-leg switches to be operated with zero-current-switching (ZCS). Meanwhile, the leading-leg switches are still operated with ZVS. The new converter is attractive for high-voltage (400-800 V), high-power (2-10 kW) applications where IGBTs are predominantly used as the power switches. The principle of operation, features, and design considerations of the new converter are described and verified on a 2-kW, 100-kHz, IGBT-based experimental circuit.

Power losses in PWM-VSI inverter using NPT or PT IGBT devices

Abstract: This paper investigates the power losses for two different IGBT technologies (nonpunch through and punch through) for use in PWM-VSI inverters in order to choose the right device technology for a given application. A loss model of the inverter is developed based on experimental determination of the power losses. The loss model is used on two different modulation strategies which are a sine wave with a third harmonic added and a 60/spl deg/-PWM modulation where only two inverter legs are active at the same time. The two IGBT technologies are characterized on an advanced measurement system which is described. The total power losses in the inverter are estimated by simulation at different conditions and it is concluded that the nonpunch through (NPT) technology is most useful for higher switching frequencies, while the punch through (PT) technology is especially useful at lower switching frequencies and high load currents. It is also concluded that the 60/spl deg/-PWM modulation has the lowest power losses and the power losses are almost independent of phase angle cos(/spl phi/) for normal motor operation. >

Fast high-power/high-voltage switch using series-connected IGBTs with active gate-controlled voltage-balancing

Abstract: There exists an acute need for fast high-voltage solid-state switches in a broad area of applications. With the proposed method of active gate-controlled voltage balancing, fast high power/high voltage semiconductor switches with working voltages of several kilovolts using series-connected insulated gate bipolar transistors (IGBT) can be realized. Transient and static voltage balancing is tested on an experimental 3.5 kV/300 A switch with three series-connected 3rd-generation IGBTs. >

Novel full bridge zero-voltage-transition PWM DC/DC converter for high power applications

Abstract: A novel full-bridge (FB) zero-voltage-transition (ZVT) PWM DC/DC converter for high power applications is proposed. An auxiliary network which consists of two small switches and one small inductor provides zero-voltage-switching (ZVS) for entire line and load ranges without increasing device voltage and current stresses. Since the ZVS range is independent of the switch capacitance, IGBTs can be used instead of MOSFETs by adding external capacitors to the switches without increasing switching losses, which allows the proposed converter to handle higher power. Operation, analysis, and features are described and verified experimentally. A 1.8 kW ZVT PWM converter prototype is compared with a ZVS PWM converter prototype of the same power rating. >

Power semiconductor devices for variable-frequency drives

Abstract: Advances in power semiconductor technology are the driving force for enhancement of the performance of variable-frequency motor drives. The development of power semiconductor devices with MOS-gate structures has enabled the control of large amounts of energy with very little input power. An equally important advancement has taken place in the development of improved rectifiers with reduced losses for high-frequency operation. In addition, the advent of MOS-gated power switches has led to the creation of smart power technology which makes compact systems with built-in diagnostic and protection functions commercially feasible. Although the power semiconductor chips are all made from silicon today, recent analysis has indicated that devices fabricated from silicon carbide have the potential for completely displacing silicon devices in the long range. >

Space vector modulated, zero-voltage transition three-phase to DC bidirectional converter

Abstract: Operation and implementation of the novel, space vector modulated, zero-voltage transition, three phase voltage source inverter/boost rectifier is presented. The converter is intended for high performance, medium power applications requiring bidirectional power flow. The proposed modified space-vector modulation allows all switches to be operated with soft-switching and constant frequency. The modulation algorithm also eliminates any low frequency distortion caused by the zero-voltage transitions and can be applied to any soft switching PWM three-phase converters. A simple, digital signal processor based implementation of the modulator and current regulators, operating with 30 /spl mu/s sampling time, is described. Measured efficiency of the 30 kHz, IGBT prototype is around 95%, and distortion of the three-phase currents is extremely small. >

A comparative study of switching losses of IGBTs under hard-switching, zero-voltage-switching and zero-current-switching

Abstract: A high power IGBT tester, based on the typical clamped inductive load circuit and incorporating zero-voltage-transition and zero-current-transition soft-switching schemes, has been developed. Both turn-on losses, including the losses associated with reverse recovery of the clamp (free-wheeling) diode, and turn-off losses are measured and compared for slow and fast IGBT devices. Benefits of zero-voltage-switching (ZVS) and zero-current-switching (ZCS) operation of IGBTs are demonstrated. The ZVS operation can reduce the total switching losses by more than half, while the ZCS reduces them by about 25% when compared with hard-switching. The ZCS turn-off also relieves the voltage stress of the IGBTs. >

A modular concept for the circuit simulation of bipolar power semiconductors

Abstract: Physical network simulation models of bipolar power devices strongly depend on an accurate description of the low-doped drift zone, because the behavior of the diffusion charge in this region governs the static and dynamic device characteristics. In this paper a one-dimensional modeling module for the drift zone is presented, which accounts for all important effects under high injection conditions: nonquasistatic ambipolar diffusion, temperature- and injection-level dependent scattering and recombination effects as well as impact ionization. When combined with well known expressions describing the rest of the respective structure, very accurate and CPU-time efficient network models can be implemented, that are suited for all applications including resonant modes (ZVS, ZCS, ZVT). The module is incorporated in a commercially available network simulator and used so far for modeling the IGBT, the high power diode and the GTO. >

Gate drive methods for IGBTs in bridge configurations

Abstract: The insulated gate bipolar transistor (IGBT) combines the advantages of both MOS and bipolar transistor technologies into a near-ideal power semiconductor switch. Of the various application areas, the use of IGBTs in the half or full-bridge power convertor configuration is very common. Such applications have typical requirements like isolated drivers, high dv/dt stress withstand, protection against shoot-through fault, etc. This paper presents various types of gate drive circuits suitable for such situations and their relative performance under actual circuit conditions. This includes pulse-transformer circuits (where a secondary power supply is not required) for PWM control, as well as opto-isolator circuits where the secondary power supply may be derived from the inverter DC bus. Protection schemes for the IGBT that can be incorporated into the drive circuit are also discussed. >

Comparative evaluation of circuit topologies for 1-phase and 3-phase boost rectifiers operated with a low current distortion

Abstract: This paper provides a survey of circuit topologies that can be used in current-controlled PWM boost rectifiers using MOSFET or IGBT type semiconductors. The topologies described are intended for controlling a nonisolated regulated DC-rail voltage whilst achieving unity fundamental power factor low current distortion operation from 60 Hz 1-phase and 3-phase AC supplies. Topologies are described for inverter legs to obtain various performance features such as low conduction losses, high efficiency, low switch count, low semiconductor voltage stresses, 3-level or 2-level PWM voltage waveform and, finally, bi-directional power conversion. Circuit topologies are described for rectifiers that use a single or a split DC-rail and for rectifiers using either AC or DC side inductors. >

A new adaptive driving technique for high current gate controlled devices

Abstract: MOSFETs and IGBTs devices are increasingly used in electronic circuits due to both the easy driving and the capability to handle high currents and voltages at high switching frequencies. This paper deals with a new driver circuit that allows optimisation of the switching speed, reduction of the energy losses during the switching time, and limiting of the electromagnetic interference (EMI). Firstly an analysis of voltage and current switching waveforms of gate insulated devices is performed. Hence, it is shown how to control voltage and current slopes independently by using a suitable adaptive driving technique based on a PLL approach. Such a technique has been adapted in order to correctly generate the gate signals regardless of the operating conditions. Finally, practical tests of the proposed driving circuit obtained using a single switch converter and IGBT devices are reported. >

A new IGBT with a monolithic over-current protection circuit

Abstract: A new IGBT structure with a monolithic overcurrent sensing and protection circuit has been developed. The feature of this device is a novel integration of a sensing and protection circuit which consists of a sensing IGBT, lateral n-MOSFET, polycrystalline silicon diode and resistor with an IGBT structure. The conventional IGBT fabrication process is available to this device with only one more photomask. Comparison of not only a short circuit safe operating area but both a trade-off characteristics between an on-state voltage drop and a turn-off loss and reverse biased safe operating area with a conventional IGBT has been investigated. Since exhibiting a large short circuit safe operating area without deterioration of any other device characteristics, this device can be applied to not only a soft switching application like voltage resonant circuit but a hard switching application like snubberless inductive load circuit.

Power transistor device having ultra deep increased concentration

Abstract: A cellular insulated gate bipolar transistor ("IGBT") device employs increased concentration in the active region between spaced bases to a depth greater than the depth of the base regions. The implant dose which is the source of the increased concentration is about 3.5×1012 atoms per centimeter squared and is driven for about 10 hours at 1175° C. Lifetime is reduced by an increased radiation dose to reduce switching loss without reducing breakdown voltage or increasing forward voltage drop above previous levels. The increased concentration region permits a reduction in the spacing between bases and provides a region of low localized bipolar gain, increasing the device latch current. The avalanche energy which the device can successfully absorb while turning off an inductive load is significantly increased. The very deep increased conduction region is formed before the body and source regions in a novel process for making the new junction pattern.

Switching voltage transient protection schemes for high current IGBT modules

Abstract: The emergence of high current and faster switching IGBT modules has made it imperative for the designers to look at ways of protecting these devices against detrimental switching voltage transients that are a common side effect of these efficient transistors. This paper discusses protection criteria for both normal switching operation and short circuit operation and covers, in detail, some of the protection schemes designed to address these problems. >

Ultimate limits of an IGBT (MCT) for high voltage applications in conjunction with a diode

Abstract: IGBTs and MCTs are power devices, which in addition to the well established thyristors and GTOs, also have a utility in high voltage applications. The static characteristics, such as blocking voltage and forward voltage drop, do not demonstrate basic physical limitations. The resulting power dissipation must be handled in such a way that certain temperature limits are not exceeded. Physically imposed limits may however become restrictive during switching, if at high current densities the time dependent dynamic blocking capability of the device can not meet the requirements imposed by the load. The interaction between the switch and freewheeling diode in hard switching modes, such as those found in chopper and converter designs, is important but not considered in publications. It is shown that in such a situation the diode may prove to be the weakest element. A safe operating area can often only be defined if the switching characteristics of the switch sufficiently reduce the requirements placed on the diode. This is relatively simple to achieve in the case of an IGBT although with a higher power dissipation in the transistor. The switching characteristics of a MCT are not readily modified and as a result a reduction in stress on the diode is only possible by means of a snubber circuit.

Power transistor module wiring structure

Abstract: In packaged bridge circuit modules with power switching transistors such as IGBT's, internal wiring inductance can cause switching voltage spikes and imbalance between switching transistors. Upon inclusion of suitably arranged and configured inductance elements, internal wiring inductance can produce a counter-electromotive force during switching. To this end, an internal connecting terminal may branch from an output terminal, a bridge-shaped internal connecting terminal may be connected between an emitter circuit pattern of one power transistor and a collector circuit pattern of another power transistor, or signal terminals as auxiliary emitter terminals of two power transistors may be connected to an inductance providing region in a current path of an emitter circuit pattern.

Method and apparatus for short circuit protection of power transistor device

Abstract: A circuit and method for detecting and protecting against an overcurrent condition in a power transistor switching device, and particularly an IGBT. The power transistor switching device has main terminals and a control terminal, the main terminal having a normal saturation voltage therebetween during normal conduction of the power transistor device. The circuit includes a driver providing control signals to the control terminal of the power transistor device for switching the power transistor device on and off, a sensing circuit coupled to the power transistor device for sensing the saturation voltage of the power transistor device, and a switching circuit coupled to the control terminal of the power transistor device and responsive to the sensing circuit for removing the control signals from the control terminal in the event the saturation voltage reaches an abnormal level indicating an overcurrent condition in the power transistor device.

A theoretical and practical consideration of optimised input filter design for a low loss matrix converter

Abstract: The paper reports the construction and testing of a matrix converter in which novel switching methods are employed to minimise the losses in the switching devices. A mixture of hard and soft commutation is used during each cycle of the output waveform. This permits losses to be reduced to a minimum while waveform quality is enhanced. IGBTs are used as the switching devices and a microcontroller generates the switching waveforms and provides control. The problems associated with input current filtering to comply with existing and possible future European EMC regulations are investigated. The paper compares disturbance voltage results from mathematical theory, computer simulation, and practical measurements from a power level converter under microprocessor control. Possible designs for an input filter to meet the European standards are considered. The relationship between the converter switching frequency and the cost of the input filter is explored.

AC/DC converter using a non-latch type switching device

Abstract: An AC/DC converter includes a rectifying circuit, a main switching device constituted by an N-channel IGBT or an N-channel FET, a control circuit, a booster circuit, and a series power supply circuit. The rectifying circuit rectifies a half wave of an input AC voltage. One end of the current path of the main switching device is supplied with a half-wave rectifying output from the rectifying circuit. The control circuit turns on the main switching device when a voltage between the gate and the other end of the main switching device exceeds a first level, and turns off the main switching device when the voltage exceeds a second level which is higher than the first level. The booster circuit boosts the voltage between the gate and the other end of the main switching device to a level which is higher than the second level when the voltage exceeds the first level. The series power supply circuit has an input terminal to which the other end of the current path of the main switching device is connected, and outputs a DC voltage.

A three-level traction inverter with IGBTs for EMU

Abstract: In order to reduce acoustic noise, size and weight of a traction inverter for electric multiple units (EMUs) connected to a DC 1500 V catenary line, the authors developed a three-level inverter using 2000 V class insulated gate bipolar transistors (IGBTs) and a novel PWM control method. This inverter consists of water cooled power units with a newly developed delta snubber circuit, which results in much lower loss compared to a conventional snubber circuit. The novel PWM control method, or multiple mode PWM control method, consists of three fundamental PWM modes and two transition modes. It is adopted not only to cover continuously the whole operational output voltage range, but also to reduce acoustic noise by making good use of the high switching frequency of the IGBTs of over 1.5 kHz. This PWM control method has five modes: the dipolar, partial dipolar, unipolar, over modulation, and one pulse modes. Transitions of each PWM mode are carried out smoothly just by controlling the modulation index and the bias. The authors also compare experimental waveforms and of the developed and the conventional two-level PWM using the developed inverter rated at 1600 k VA. The motor currents are less distorted than the conventional PWM because of both the multiple mode PWM at switching frequencies over 1.5 kHz and the three-level configuration. In particular, the motor currents are almost sinusoidal in the range between the dipolar and unipolar modes. The authors also verify that the acoustic noise from the induction motor is successfully reduced by approximately 15 dBA. >

IGBT with increased ruggedness

Abstract: An auxiliary MOSFET is integrated into a lateral IGBT structure with the source and drain of the auxiliary MOSFET in parallel with the emitter-base circuit of the IGBT. A driver, integrated with the IGBT chip, turns off the base emitter voltage to the IGBT before turning off the auxiliary MOSFET during turn off. The auxiliary MOSFET is turned off again at the beginning of the conduction period to ensure full conductivity modulation of the DMOS drain and maximum gain of the PNP transistor. Short circuit protection and overtemperature protection circuits are also integrated into the chip.

Packaging and performance of an IGBT-based hybrid electric vehicle

Abstract: A highly integrated hybrid electric vehicle of the series architecture has been built and tested. The vehicle essentially matches the performance of the stock car on which it is based-including full interior space, range, and dynamic performance. It approaches Federal ULEV targets with the engine in operation, and provides sufficient zero-emission (electric only) range for typical commuting. This is achieved by means of an integrated battery package, an air-cooled traction package, and industrial IGBT drives. The arrangement and package designs are discussed, with an emphasis on the electrical architecture and the power electronic drive trains. Operating results are reported.

Analysis and optimization of regenerative linear snubbers applied to switches with voltage and current tails

Abstract: Among the trends notable in modern power electronic converters, the following two are of particular importance: the interest in and growing application of soft switching techniques and the widespread use of the newer device types, such as the IGBT. In this paper, a new approach to the optimization of total losses for these device types is proposed. To describe the tail-forming characteristics of devices such as the IGBT, GTO, and MCT better, the changing device parameters are modeled by two linear segments of different gradients. The switching losses of devices that exhibit tail characteristics are analyzed using this modeling approach. The snubber size is optimized for minimum total losses with respect to the recovery efficiency of the snubber circuit. The validity of the proposed description is confirmed by independent experimental results. >

Bidirectional AC switching device with MOS-gated turn-on and turn-off control

Abstract: A bidirectional semiconductor switching device includes a semiconductor substrate having first and second device terminals on opposite faces thereof, a thyristor in the substrate for providing regenerative conduction in a first direction, between the first device terminal and the second device terminal, and an insulated-gate bipolar junction transistor (IGBT) in the substrate for providing nonregenerative conduction in a second opposite direction, between the second device terminal and the first device terminal. In particular, the switching device includes first and second adjacent trenches therein at a face and respective first and second insulated-gate field effect transistors (IGFETs) in the trenches for providing gate-controlled turn-on and turn-off of the thyristor and the IGBT, by being electrically connected in series therewith.

Audible noise and losses in variable speed induction motor drives with IGBT inverters-influence of the squirrel cage design and the switching frequency

Abstract: This paper describes a large number of experiments comparing audible noise, losses and efficiency of different induction motors supplied by an IGBT inverter. The influence of the switching frequency on the motor behaviour is analysed. As a comparison the motor is also supplied directly from the mains. Furthermore two different motors are compared to study the influence of the rotor cage design on the motor behaviour. It is shown that the choice of the switching frequency has a large influence on the audible noise produced by induction motors. By taking higher switching frequencies, the time harmonics move to a nonaudible region. At some higher switching frequencies subharmonics appear, having a bad influence on the audible noise. At higher fundamental frequencies the audible noise of the fan dominates. The switching frequencies can cause pure tones that are very disturbing to the human ear. The influence of the switching frequency on the efficiency is rather small. Minimal overall losses appear around 3 and 4 kHz. The voltage-frequency ratio should be taken constant from the point of view of the efficiency. >

A novel scheme for protection of power semiconductor devices against short circuit faults

Abstract: Power semiconductor devices find wide application in modern power electronic converters. Protection of these devices against overload/short circuit conditions is of paramount importance. Present day protection topologies employing different circuits have invariably one main drawback in that the fault current reaches the set value before action is initiated to trip the system. This poses a severe stress on the device. Hence an adequate safety margin has to be necessarily provided to prevent excessive device stresses and care has to be taken to see that the device is operated well within its safe operating areas. The present paper proposes a method wherein the slope or rate of rise of the fault current is detected and once the slope exceeds the set reference, action is initiated to trip the system much before the fault current reaches dangerous levels. The method provides a fast means of detection of overload and short circuit currents and can be conveniently adopted for the protection of devices in power transistor/IGBT based inverters against short circuited load conditions or shoot through faults. The possible reduction of stresses in the power devices are also highlighted. >

Rogowski transducers for high bandwidth high current measurement

Abstract: The 300A Rogowski current waveform transducer was tested using a simple IGBT switch with an inductive load. A 5m Omega co-axial shunt was connected in series with the IGBT for comparison. The initial current at turn-on is due to snubber discharge; thereafter the inductor current ramps up until the IGBT is turned off. The current waveforms closely correspond even with a turn-off slope in excess of 500A/ mu s. Tests with a 1500A Rogowski transducer have reproduced current transients in excess of 2000A/ mu s. For use for the measurement of high frequency power, or power associated with semiconductor switching transients, a small time delay of 90ns should be introduced into the voltage measurement signal before multiplying this by current to obtain the instantaneous power. It is concluded that the Rogowski coil with appropriate integrator design can provide current waveform measurement to a very high bandwidth in excess of 1MHz, and forms a very attractive easy-to-use measuring instrument.

Semiconductor device and its manufacture

Abstract: PURPOSE:To prevent malfunction and breakdown of semiconductor constituting a control part, and reduce the consumption current of a semiconductor integrated circuit for switching control, by making the discharge current due to the feedback capacitance or the like of a switching element bypass the semiconductor integrated circuit for switching control, in a semiconductor device having a power MOSFET constituting an inverter or the like and a switching element like an IGBT. CONSTITUTION:A current bypass route is formed by arranging a Schottky barrier diode 27, from the output terminal 13 of a power MOSFET 11 toward a control terminal 12 in which a control signal is inputted. The Schottky barrier diode 27 has a small voltage drop in the forward direction and can bypass a discharge current by a voltage lower than or equal to the backward saturation voltage of a transistor 23 in a control part 20, so that malfunction and breakdown of the transistor 23 can be prevented, and a consumption current can be reduced by decreasing the penetration current.

Switch mode power supply with BJT/MOSFET cascode circuit

Abstract: Switched-mode power supplies in which a series arrangement of a bipolar transistor and a MOS field effect transistor is used are known and referred to as cascode circuits. In these circuits the bipolar transistor is switched (with the MOS field effect transistor) via the emitter instead of with the base. Since the collector current of the bipolar transistor may vary over a large range, the base should be proportionally driven to prevent the bipolar transistor from getting either above or below its normal operating range. By making use of an extra winding on a transformer arranged in series with the cascode circuit, a non-dissipative proportional drive of the base of the bipolar transistor is obtained. The extra winding is coupled to the base via an inductance.