Main Switching Devices Research Articles

T Source Inverter Based Shunt Active Filter with LCL Passive Filter for the 415V 50 Hz Distribution systems

The inverter topology is being used as an active filter to reduce the harmonics in the power system. The traditional voltage source or current source inverters are having the disadvantages of limited output voltage range hence it may not be able to supply enough compensating currents during heavy switching surges, Vulnerable to EMI noise and the devices gets damaged in either open or short circuit conditions and the main switching device of VSI and CSI are not interchangeable. The active filters are the type of DC-AC system with wide range of voltage regulation and integration of energy storages is often required. This cannot be achieved with conventional inverters and hence the impedance source inverters have been suggested. The T source inverters are basically impedance source inverters which can be used as an active filter in the power system. The MATLAB simulation is done and the results are discussed in this paper for both the types. The proposed dampening system is fully characterized by LCL based passive filters and T source inverter based shunt active filter. The disturbances in the supply voltage and load current due to the non linear loads are observed in the simulation. The same is studied after connecting the designed hybrid shunt active filter in the distribution system. The simulation results obtained from the proposed method proves that it gives comparatively better THD value.

Design of Switched Reluctance Motor Speed Control System Base on DSP

Switched Reluctance Motor has become one of hot topics of the international transmission for its simple structure,wide speed range and low cost, etc. In this thesis, based on TI's 32-bit DSP (TMS320F240) and following the principles of structure matching, high efficiency, easy to control, switched reluctance motor speed control system is designed using a minimum program of the main switching device. The parts of design include power converter, controller and software components.

Distributed Impedance Network (Z-Network) DC–DC Converter

This paper presents a novel dc-dc converter incorporating a distributed impedance-source network (Z-source network, or Z-network) to achieve the buck (step-down) and boost (step-up) function of a transformer-isolated dc-dc converter. In this paper, the distributed impedance source network composed of an array of inductors and capacitors is coupled between power source and main switching devices. The great and unique feature about the distributed impedance source network dc-dc converter is that unlike the traditional V-source or I-source converters, it can be open- and short-circuited without damaging switching devices. Therefore, the desired buck and boost function can be achieved. Moreover, converter reliability can be greatly improved. A dc-dc converter using this proposed concept is built and tested. Its performances are verified with experimental results.

Experimental Verification of Current-Source Inverter With ZVS Commutation Circuit

This paper presents a current-source inverter suitable for high-voltage/high-power motor drives. This inverter uses thyristors as main switching devices and utilizes a zero-voltage-switching (ZVS) commutation circuit. It has the advantages of good motor power factor and self-startability. We have evaluated a test model of the proposed inverter and a motor and verified that the inverter operates at a motor power factor of one and that it can be started even when the motor speed is zero. Moreover, a six-phase synchronous motor was driven by two of these inverters; it was confirmed that they decreased the motor torque ripple and the harmonic component of the voltage source. In addition, we evaluated the operation of the ZVS commutation circuit by simulation and experiment and thus verified that turnoff loss depends mainly on the inductance of the ZVS commutation circuit and not on gate resistance. Moreover, when the switching device turns off the current, its voltage is almost zero. That is, even if the inductance is large, the peak voltage of the switching device is low and switching loss is small. Therefore, the ZVS commutation circuit can be easily composed because it does not need to be of low inductance. These results show that a large-capacity drive system can be easily achieved with the proposed inverter.

Digital Controlled High Power Mid-Frequency Pulsed Power Supply

In this article a novel scheme of high power mid-frequency pulse power supply is proposed. The supply is made up of two major stages. First stage is dual interleaved buck chopper stage in order to make the DC bus and output pulse voltage controllable. Second stage is a inverter converting the DC voltage into a series of square AC voltage pulse. IGBT module(300A-1200V) is used as the main switch device for the proposed supply is a high power application. As we know large capacity power IGBT module can hardly work as high as 40Khz[1], so to solve this problem, interleaved control scheme is incorporated. Basic ideas are to share the total switching losses. To combine several converters working under certain sequence is the key point. Final output pulse frequency is 20-40Khz,voltage level is 0-800V, and pulse width is 0-90% changeable. The whole system is concise effective. Experimental results verified the feasibility of abovementioned power supply.

A 120-W Boost Converter Operation Using a High-Voltage GaN-HEMT

A boost converter with a 940-V/4.4 A GaN-HEMT as the main switching device was demonstrated to show the possibility of using high-voltage GaN-HEMTs in power electronic applications. The demonstrated circuit achieved an output power of 122 W and a power efficiency of 94.2% under a drain peak voltage as high as 350 V and a switching frequency of 1 MHz. The dual field-plate structure realized high-voltage switching operation with high power efficiency as dynamic on-resistance was suppressed by an increase of the current collapse phenomena.

Demonstration of 13.56-MHz class-E amplifier using a high-Voltage GaN power-HEMT

A 13.56-MHz class-E amplifier with a high-voltage GaN HEMT as the main switching device is demonstrated to show the possibility of using GaN HEMTs in high-frequency switching power applications such as RF power-supply applications. The 380-V/1.9-A GaN power HEMT was designed and fabricated for high-voltage power-electronics applications. The demonstrated circuit achieved the output power of 13.4 W and the power efficiency of 91% under a drain-peak voltage as high as 330 V. This result shows that high-voltage GaN devices are suitable for high-frequency switching applications under high dc input voltages of over 100 V.

A Generalized Undeland Snubber for Flying Capacitor Multilevel Inverter and Converter

This paper proposes a snubber circuit for a flying capacitor multilevel inverter and converter. It also explains the concept of constructing a snubber circuit for a multilevel inverter and converter. The proposed snubber circuit makes use of an Undeland snubber as a basic snubber unit, and thus can be regarded as a generalized Undeland snubber for a flying capacitor multilevel inverter and converter. It has such an advantage of Undeland snubber used in the two-level inverter. Compared with a conventional RLD/RCD snubber for multilevel inverter and converter, the proposed snubber keeps such good features as fewer number of components, reduction of voltage stress of main switching devices due to low overvoltage, and improved efficiency of system due to low snubber loss. In this paper, the proposed snubber is applied to a three-level flying capacitor inverter, and its features are in detail demonstrated by computer simulation and experimental result.

High Breakdown Voltage Undoped AlGaN–GaN Power HEMT on Sapphire Substrate and Its Demonstration for DC–DC Converter Application

Undoped AlGaN-GaN power high electron mobility transistors (HEMTs) on sapphire substrate with 470-V breakdown voltage were fabricated and demonstrated as a main switching device for a high-voltage dc-dc converter. The fabricated power HEMT realized a high breakdown voltage with a field plate structure and a low on-state resistance of 3.9 m/spl Omega//spl middot/cm/sup 2/, which is 10 /spl times/ lower than that of conventional Si MOSFETs. The dc-dc converter operation of a down chopper circuit was demonstrated using the fabricated device at the input voltage of 300 V. These results show the promising possibilities of the AlGaN-GaN power HEMTs on sapphire substrate for future switching power devices.

Snubber circuit for diode-clamped four-level inverter and converter

The snubber circuit makes use of Undeland and McMurray snubbers in the basic snubber unit, and can be regarded as a generalised combined Undeland and Mcmurray snubber. The proposed snubber features fewer components, improved efficiency due to low snubber loss, overvoltage clamping across main switching devices, and no imbalance problem of the blocking voltage. The proposed concept of constructing a snubber circuit for a four-level inverter and converter can apply to any level of converter and inverter.

Design of LIGBT protection circuit for smart power integration

Development of a monolithic power integrated circuit by making the lateral insulated gate bipolar transistor (IGBT) the main switching device is a current topic. The overcurrent protection scheme is usually necessary to be built as part of the function in such a power integrated circuit. The protection circuit requires distinguishing various fault conditions and reacting differently based on the device safe operating area (SOA) limitation. At the same time, the protection circuit should also be relatively concise and suitable for integration. In this paper, a concise circuit suitable for integration and with gate drive capability is proposed to provide the complete function of overcurrent SOA protection for the LIGBT. The operational principle was described in detail and the circuit performance was verified with experimental results from both the discrete circuit and the fabricated LIGBT integrated circuit.

A ZVT quasi-resonant PWM converter for unity power factor application

In this paper, a new quasi-resonant PWM converter topology is proposed. This converter achieves zero-voltage transition (ZVT) conditions for both the main and auxiliary switching devices, and the blocking voltage of them has been clamped at a relatively low level during off period. The operating modes of the converter are analysed and described here. The proposed converter can be used for high frequency DC/DC conversion with a unity power factor. A laboratory prototype was built and experimental results were obtained for verification purposes.

Sine Wave PWM Inverter using Zero Current Switching at Turn-On.

In a PWM inverter, the PWM signal with the dead-time is usually used to protect the short-phenomenon of a pair of main switching devices in the inverter. The dead-time causes the waveform distortion in the output voltage and interrupts the high carrier frequency drive of the inverter. In order to solve these problems, a novel PWM inverter is proposed in this paper. The proposed PWM inverter is realized by performing zero current switching at the turn-on of the main switching devices and generates the output voltage without a waveform distortion, although the inverter is driven by the PWM signal with the dead-time. The zero current switching is achieved by connecting in series an inductor and a capacitor between the output terminals of a conventional inverter.

Steady-state performance of the DC motor supplied from single-phase rectifier with step-up converter-a unity power factor converter

It is shown that the voltage step-up converters supplying DC motors can be operated at a unity power factor when supplied from single-phase rectifiers. If the duty ratio of the main switching device in the step-up converter is continuously adjusted, it is possible to maintain the line current almost sinusoidal and in phase with the input voltage. This remarkable property can be obtained from a certain minimum critical current up to values in excess of the rated armature current. >

A New Neutral-Point-Clamped PWM Inverter

A new neutral-point-clamped pulsewidth modulation (PWM) inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed. This inverter output contains less harmonic content as compared with that of a conventional type. Two inverters are compared analytically and experimentally. In addition, a new PWM technique suitable for an ac drive system is applied to this inverter. The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.

Inverter Drive for Doubly Salient Reluctance Motor: Its Fundamental Behaviour, Linear Analysis and Cost Implications

A variable-speed drive using a doubly salient variable reluctance motor, because of its ability to operate efficiently from unidirectional winding currents, enables the number of main switching devices in the inverter to be halved, yielding a very economical brushless drive. The drive is analysed using a linear model for the motor, yielding phase-current waveforms which enable an economical design for the thyristor inverter and provide guidance for a motor design which will optimise the performance/cost ratio of the drive as a whole. A control strategy for firing and turning off the inverter thyristors at appropriate rotor angles for a traction application also emerges from the analysis. Experimental waveforms exhibit shapes similar to those predicted, and the results of this analysis have been of great value in designing such a drive for a battery vehicle.