Voltage IGBT Research Articles

Evaluation of voltage source IGBT converters for three-phase induction motor drives

Modern induction machine (IM) drives are subject to a variety of system perturbations, i.e., weak grid conditions and the resulting DC-link voltage fluctuations, that could possibly compromise machine performance characteristics such as speed, torque, and load current. This paper investigates such circumstances, specifically the influence of DC-link variations on the IM drive under different control and modulation strategies and addresses the timely issues of power loss calculation methods in the most common voltage source three-phase PWM converters (VSC) with active front-end unit (AFE). The AFE converts the AC line input into a controlled DC-link voltage, which is then used as input into a three-phase IM drive, based on an IGBT voltage source inverter (VSI). It should be noted that within this work an AFE is used to control the DC link voltage, ultimately mimicking weak grid conditions. The AFE of the IM drive adopts the hysteresis-based modulation technique and the VSI is controlled by space vector PWM-based methods. The IM drive will be evaluated using different control strategies and verified based on the test-bed using a control system rapid prototyping environment such as dSPACE.

A new mathematical tool to investigate the influence of cable characteristics and IGBT fast switching on voltage transients and differential mode currents for PWM drives

The authors propose a new mathematical tool to investigate the influence of cable characteristics upon pulse voltage transients and their associated differential mode (DM) currents in PWM long cable drives. Even if reflected wave transient voltages have received considerable investigation for IGBT voltage source inverters, the modeling and simulation of these voltage transients still require precise modeling. Moreover, another consequence of the IGBT fast rise time, which is the resulting high frequency DM current, has not been previously examined in detail for these systems. This paper presents fully developed mathematical formulas for both pulse voltages and their resulting DM currents at any point along the inverter-to-motor cable. Using the developed formulas, an appropriate tool has been built, using SimPowerSystems (SPS) and Simulink of Matlab software, to predict the high frequency over-voltages and their associated DM currents all along the feeding cable. This tool has then been applied to an industrial 5 kV A PWM drive prototype using a 4-wire shielded long cable. Some simulation results and experimental validations are included.

Compact High Voltage IGBT Switch for Pulsed Power Applications

This paper describes the development of a semiconductor based switch for use in pulsed power technology. Because of the more stable operating conditions, given by the semiconductor devices, this switch could be used to replace the up to now in pulsed power technology common used spark gaps. We defined a technical concept for a semiconductor based switch with a maximum voltage of 20 kV and a current capability in the order of 1 kA. This concept also should enable to generate pulses widths of a few mus. We found an IGBT with a maximum blocking voltage of 1700 V, a signal rise time of 100 ns, and a short circuit current rate of 650 A to be suited to realize our concept for the switch. Because of the defined maximum voltage of 20 kV it was necessary to use a series connection of the IGBTs. To ensure a synchronous switching of the in series connected devices, a trigger unit was built up which was inductively connected to the driver circuits of the single IGBTs. Single devices where tested and separated for the series connection. With the handicap of a given 155 mm circuit board we designed a complete switch, basing on industrial standards, with 15 IGBTs and a finally maximum blocking voltage of 18 kV, and a current capability of 500 A. The design of this circuit also included the development of a protecting circuit (active clamp) to protect the single devices of an over voltage damage during the switching, and also to avoid an inhomogeneous split up of the voltage to the different devices.

A Pulsed Power Supply Based on Power Semiconductor Switches and Transmission Line Transformer

Transmission line transformers (TLT's) as pulse transformers have received increasingly more attention due to their excellent frequency response characteristics over conventional wound transformers. This transformer basically consists of equal lengths of transmission line (normally coaxial cables are used) connected in parallel at the input side of the transformer, and in series at the output side so that the output voltage can be boosted in proportion. Because the reactance of the outer conductor increases with the rise of the frequency of the input voltage, the output voltage of each transmission line can be isolated mutually when the frequency is high enough. Then, the output voltage will be amplified through the voltage superposition. To minimize the substantial loss of voltage gain and obtain a low pulse droop rate, one stage transformer is entwined together as a unit, the number of stages of the transformer can increase easily by piling units one by one. This spiral construction makes the transmission line transformers much more compact. On the other hand, with the development of modern semiconductor technology, high voltage, fast rise time power semiconductor devices have been produced, the collector emitter breakdown voltage of one IGBT is to 1.7 kV and the rise time is 100 ns. This paper describes a kind of compact pulse power supply constructed by combining transmission line transformer and modern power semiconductor devices-IGBTs. High voltage IGBTs (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CES</sub> =1.7 kV) have been used as charge switches, short pulses can be obtained at the input port of the transformer, then the output pulse amplitude is 10 kV through a 10-stage transmission line transformer. Finally, the output voltage pulse waveforms are given in the paper.

A high-performance IGBT with new N+ buffer structure

We propose a new IGBT structure with a new N+ buffer, and confirm by experiments and numerical simulations that the new IGBT is superior to the conventional one. The following results were obtained. (1) According to our experiments, the new IGBT was able to decrease the total power loss, and the parallel operation became easier, compared with the conventional IGBT. Moreover, the short-circuit ruggedness of the new IGBT was almost the same as that of the conventional one by optimizing the ratio of the N++ buried layer. (2) We clarified why the characteristics of the new IGBT were improved by numerical simulations. (a) When the new IGBT is on, holes injected from the P+ substrate flow through, remaining out of the N++ buried layer. Also, the holes rapidly turn around in the N++ buried layer when passing by, and the hole concentration becomes even. Because the lifetime of the new IGBT is designed to be long, the hole concentrations of the new IGBT increases in the N− layer. Therefore, the saturation voltage of the new IGBT is lower than that of the conventional IGBT. (b) Since the lifetime of the N− layer of the new IGBT can be extended, the temperature dependence of the lifetime becomes small, and IZTC of the new IGBT is improved. (c) In the turn-on state, the holes are injected through the N+ buffer layer with lower concentration from the P+ substrate, thus the turn-on speed of the new IGBT become quicker and the turn-on loss of the IGBT is reduced. (d) In the turn-off state, as the N− layer is depleted completely, the carriers in the N+ buffer layer mainly influence the tail current. There are few carriers in the N++ buried layer of the new IGBT, so the turn-off loss of the new IGBT is reduced. (e) Since the effect to prevent the holes being injected from the P+ substrate affects the N− layer, the number of carriers of the N− layer of the new IGBT is limited in the saturation current region. Therefore, the saturation current is also controlled, and the short-circuit ruggedness of the new IGBT is not diminished.

A New 1200 V Punch Through-Insulated Gate Bipolar Transistor with Protection Circuit Employing Lateral Insulated Gate Bipolar Transistor and Floating p-Well Voltage Sensing Scheme

A new 1200 V punch through-insulated gate bipolar transistor (PT-IGBT) with a protection circuit employing a lateral IGBT (LIGBT) and a floating p-well voltage sensing scheme is proposed and implemented by fabricating the main IGBT and gate voltage pull-down circuit using the widely used planar IGBT process. The detection of the fault and gate voltage pull-down operations is achieved using the floating p-well sensing scheme. The LIGBT used as a pull-down transistor reduces the area of the protection circuit due to the enhanced current handling capability. The voltage saturation effect of a floating p-well voltage under the high voltage condition provides the 1200 V PT-IGBT with a reliable and rapid protection by preventing the gate oxide failure of the pull-down LIGBT and eliminating the blanking filter.

The high frequency behaviour of high voltage and current IGBT modules

Sharp voltage gradients act as a stimulus for high power IGBT modules, which can exhibit a potentially instable high frequency behaviour. In fact, they can act as a radio frequency amplifier and, in particular operating conditions, the interaction between the device and the control or the external circuit can cause self-sustaining oscillations or the enhancement of the unevenness in current distribution inside a power module thus having a significant impact on the reliability of the power converter. Moreover, this RF amplification worsen the generated EMI (Electro Magnetic Interference). This paper presents an extensive experimental investigation about the high frequency behaviour of IGBT high power modules. The measurements were performed by means of an original experimental set-up that was specifically conceived and constructed. The data are analysed with the help of a theoretical small signal model which is able to describe RF behaviour of high power IGBT modules.

Shunt Active Filter Controlled by Fuzzy Logic

Harmonics contamination is a serious and a harmful problem in electric power systems. Active power filtering constitutes one of the most effective proposed solutions. A shunt active power filter that achieves low current total harmonic distortion THD, reactive power compensation, and power factor correction is presented. The topology is based on IGBT's voltage inverter, intended to damp harmonics produced by a diode rectifier. The main paper's contribution is the use of the notch filter method, consisting solely of two serial band-pass filters, for reference currents calculation, and the application of fuzzy logic for better active filter current control accuracy. The gating signals were generated through the carrier-based PWM strategy. Simulation works of the studied model, using SIMULINK under MATLAB software, revealed satisfying results in transient and steady states.

Dual three-phase induction motor drive with digital current control in the stationary reference frame

Vector control of a dual three-phase induction machine, with two sets of three-phase stator windings spatially shifted by 30 electrical degrees, is elaborated in the paper. The stator windings are fed from a current-controlled PWM six-phase IGBT voltage source inverter (VSI). The main problem in realisation of such a drive is an adequate current control algorithm, which has to cope with the inherent asymmetries of the drive. Furthermore, the digital implementation has to ensure zero steady state current error for the whole frequency range of the drive. After reviewing the existing solutions, the paper proposes a current control scheme that is based on four digital current controllers in the stationary reference frame. A design procedure for the current controllers is presented and current controllers are implemented in a laboratory test rig, in conjunction with a previously developed PWM scheme that provides operation with low values of low-order output voltage harmonics. Experimental tests are conducted and the results are given for a direct rotor field oriented control (DRFOC) of a 10 kW dual three-phase induction motor drive prototype. The results confirm the validity of the control scheme.

Power Loss-Oriented Evaluation of High Voltage IGBTs and Multilevel Converters in Transformerless Traction Applications

The low-frequency line transformer in todays ac rail vehicles suffers from poor efficiency and a substantial weight. Future traction drives may operate directly from the mains without this transformer. A feasible concept for a transformerless drive system consists of series connected medium voltage converters applying modern high-voltage insulated gate bipolar transistors (HV-IGBTs). In a first design step, the switching characteristics and losses of 6.5-kV IGBTs are compared to 3.3-kV and 4.5-kV IGBTs which are already commercially used in traction applications. Based on the considered HV-IGBTs, the properties of multilevel converters are analyzed and their applicability to the transformerless system is evaluated. The paper focusses on a loss analysis of the converters. Reliability aspects and harmonic spectra are briefly discussed. Taking these design aspects into account, the three-level neutral point clamped converter turns out to be a reasonable solution to realize line and motor converter modules in a transformerless traction system.

Premium Quality Power Park Based on Multi-Terminal HVDC

Subtransmission and distribution systems in large cities are often served by underground cable systems. Because of the compactness and the reduced cost of dc cable transmission lines, a Multi-Terminal HVDC system based on IGBT Voltage Source Converters (VSCs) can be an attractive alternative to an ac cable system. This paper draws attention to the added value which comes from the capability of Multi-Terminal HVDC (VSC-M-HVDC) system to ensure uninterrupted quality power to sensitive loads. The value of Premium Quality Power Park obtainable from a VSC-M-HVDC system should enhance its attractiveness.

Investigation of the power dissipation during IGBT turn-off using a new physics-based IGBT compact model

New compact models of the IGBTs (both non-punch through IGBT (NPTIGBT) and punch-through IGBT (PTIGBT)) are presented in this paper. The models are implemented in the SABER circuit simulator and used for a study of IGBT anode current and voltage characteristics during a device turn-off (clamped inductive load circuit with gate controlled turn-off), since these parts of the transient characteristics essentially predict the power dissipation ( V× I) inside the device. It is shown that PTIGBTs are faster than NPTIGBTs, this becoming more apparent at higher clamp voltages.

Active-gate-control for Snubberless IGBTs connected in Series

High voltage IGBT converters require an IGBT series connection. To reduce converter loss and simplify converter configuration, snubber circuits should be omitted. In this paper we introduce our snubberless IGBT series connection technique with active-gate-control.In the active-gate-control IGBT, gate-voltage is set to increase with collector-voltage. Due to increased gate-voltage, IGBT impedance drops and the collector-voltage is limited. The collector-voltages of IGBTs connected in series can be balanced by uniting the collector-voltages of each single IGBTs independently. In the active-gate-control, the gate is charged before the collector-voltage reaches the clamping voltage. So fast control can be performed and surge voltages at the recovery state can be clamped. In the control the clamping voltage increases with tum-off current and it is saturated for further larger currents. By increasing the clamping voltage with tum-off current, the increase of tum-off loss caused by collector voltage clamping is limited. Saturating the clapping voltage for further higher currents prevents overvoltage failure.

Fail-safe capability of a high voltage IGBT inverter source

The aim of this paper is to explain the intrinsic fail-safe capability of a high-voltage IGBT inverter source. The inverter is an imbricated cells structure which provides redundancy. The major failures can be either a wrong gate voltage (malfunctioning of the driver board, auxiliary power supply failure, d v /d t disturbance) or an intrinsic IGBT failure (over-voltage/avalanche stress, temperature overshoot). The IGBT failures are studied and show that no opening of the bondings can appear and consequently no risk of explosion. Owing to the imbricated cells structure, an IGBT failure can be withstand a few switching periods, with nevertheless non-optimized output waveforms. The design and the lab-test of a sensor able to perform monitoring and failure diagnosis are also presented. This real-time diagnosis allows either a safety stop or a remedial control strategy based on the reconfiguration of the control signals. The real-time reconfiguration allows to decrease internal stresses and to optimize the shape of the output voltage. In this case, a fail-safe operating may be gained for high power applications.

A Novel Parallel-Connected Multiple Induction Motors Vector Control Method for the Rolling Stock Traction System

In the field of the rolling stock traction system, one inverter often drives multiple induction motors connected in parallel, because of its compactness, lightness and economical advantages. A high performance three level invereter system using high voltage and large current IGBTs that can drive multiple induction motors has been widely adopted. On the other hand, in order to provide passengers of comfortable ride feeling and to keep the train schedule even in rainy days, an accurate and responsive motor torque control is demanded. Considering this situation, we have already developed a stator-flux-oriented vector control method for the rolling stock traction system in which one inverter feeds multiple induction motors. Here, we have newly developed a novel vector control method which can improve the stability of the traction system and the motor torque response. We have also evaluated the proposed control method through stability analysis, simulations and experiments. This paper presents the principle of this control method and the mechanical and electrical models of the rolling stock traction system, as well as stability analysis, simulation and experimental results.

Study Of Oscillation In High Voltage Diode At Recovery Operation

At present, switching devices such as GCT (Gate Commutated Turn-off) thyristor and HVIGBT (High Voltage IGBT) are remarkably progressing and able to switch fast at high DC operation voltage above 2.5kV. However, a freewheeling diode which should realize the recovery performance similar to the turn-on performance of switching devices is not developed. In the high voltage diode, a main problem of the recovery performance is to prevent the voltage-oscillation. The voltage-oscillation brings miss-operation of driving circuit or voltage destruction of oneself. As the diode during the recovery operation can be regarded as a combination of one capacitance and two resistances, the oscillation mechanism was studied by replacing the diode to LCR circuit. As this results, it was clear that the diode during the recovery operation made surely the oscillation. On the basis of this analysis, the diode structure to mitigate oscillation was proposed.

An IGBT turn-on snubber circuit with passive energy recovery

An inductive turn-on snubber with passive energy recovery for IGBTs used in single ended applications and asymmetrical half bridges is presented. Snubber inductive stored energy at switch turn-off is passively recovered into the load. In so doing, limited capacitive turn-off snubbering is inherently achieved, which reduces IGBT voltage during its tail current period. Turn-on snubber energy associated with freewheel diode reverse recovery at switch turn-on, is intrinsically recovered into the load. The times for snubber set and reset are fixed, being independent of the load current magnitude. Functionality of the snubber is supported by mathematical analysis, transient analysis simulations and practical results, based on a 450V, 33A, 10kHz, IGBT switching circuit. For GTO thyristors the snubber can be modified to give capacitive turn-off snubber action from zero volts.

Extrapolation of cosmic ray induced failures from test to field conditions for IGBT modules

Recently it was found that biased high voltage IGBTs are more vulnerable to cosmic ray failures devices like GTOs or thyristors. In order to obtain a reliable extrapolation from test to operating field conditions acceleration factors other than voltage are needed. For this purpose we exposed IGBTs and module diodes to an accelerator neutron beam and to the enhanced cosmic ray flux at 3580 m altitutde above sea level. We conclude that neutrons are the most critical particles in cosmic ways with regard to potential device failures.

A high-performance IGBT with new N+ buffer structure

We propose a new IGBT structure with a new N+ buffer, and confirm by experiments and numerical simulations that the new IGBT is superior to the conventional one. The following results were obtained. (1) According to our experiments, the new IGBT was able to decrease the total power loss, and the parallel operation became easier, compared with the conventional IGBT. Moreover, the short-circuit ruggedness of the new IGBT was almost the same as that of the conventional one by optimizing the ratio of the N++ buried layer. (2) We clarified why the characteristics of the new IGBT were improved by numerical simulations. (a) When the new IGBT is on, holes injected from the P+ substrate flow through, remaining out of the N++ buried layer. Also, the holes rapidly turn around in the N++ buried layer when passing by, and the hole concentration becomes even. Because the lifetime of the new IGBT is designed to be long, the hole concentrations of the new IGBT increases in the N− layer. Therefore, the saturation voltage of the new IGBT is lower than that of the conventional IGBT. (b) Since the lifetime of the N− layer of the new IGBT can be extended, the temperature dependence of the lifetime becomes small, and IZTC of the new IGBT is improved. (c) In the turn-on state, the holes are injected through the N+ buffer layer with lower concentration from the P+ substrate, thus the turn-on speed of the new IGBT become quicker and the turn-on loss of the IGBT is reduced. (d) In the turn-off state, as the N− layer is depleted completely, the carriers in the N+ buffer layer mainly influence the tail current. There are few carriers in the N++ buried layer of the new IGBT, so the turn-off loss of the new IGBT is reduced. (e) Since the effect to prevent the holes being injected from the P+ substrate affects the N− layer, the number of carriers of the N− layer of the new IGBT is limited in the saturation current region. Therefore, the saturation current is also controlled, and the short-circuit ruggedness of the new IGBT is not diminished. © 1998 Scripta Technica, Electr Eng Jpn, 124(4): 37-46, 1998

N&lt;sup&gt;++&lt;/sup&gt;埋め込みバッファ領域を有する新型IGBT

We propose a new IGBT structure with a new N+ buffer, and confirm by experiments and numerical simulations that the new IGBT is superior to the conventional one. The following results were obtained. (1) According to our experiments, the new IGBT was able to decrease the total power loss, and the parallel operation became easier, compared with the conventional IGBT. Moreover, the short-circuit ruggedness of the new IGBT was almost the same as that of the conventional one by optimizing the ratio of the N++ buried layer. (2) We clarified why the characteristics of the new IGBT were improved by numerical simulations. (a) When the new IGBT is on, holes injected from the P+ substrate flow through, remaining out of the N++ buried layer. Also, the holes rapidly turn around in the N++ buried layer when passing by, and the hole concentration becomes even. Because the lifetime of the new IGBT is designed to be long, the hole concentrations of the new IGBT increases in the N− layer. Therefore, the saturation voltage of the new IGBT is lower than that of the conventional IGBT. (b) Since the lifetime of the N− layer of the new IGBT can be extended, the temperature dependence of the lifetime becomes small, and IZTC of the new IGBT is improved. (c) In the turn-on state, the holes are injected through the N+ buffer layer with lower concentration from the P+ substrate, thus the turn-on speed of the new IGBT become quicker and the turn-on loss of the IGBT is reduced. (d) In the turn-off state, as the N− layer is depleted completely, the carriers in the N+ buffer layer mainly influence the tail current. There are few carriers in the N++ buried layer of the new IGBT, so the turn-off loss of the new IGBT is reduced. (e) Since the effect to prevent the holes being injected from the P+ substrate affects the N− layer, the number of carriers of the N− layer of the new IGBT is limited in the saturation current region. Therefore, the saturation current is also controlled, and the short-circuit ruggedness of the new IGBT is not diminished. © 1998 Scripta Technica, Electr Eng Jpn, 124(4): 37-46, 1998