Development of a pulse power converter with a DSP instantaneous current control

A large-capacity inverter using high-power gate turn-off (GTO) thyristors that can be used instead of a cycloconverter in AC drives is presented. With the techniques of multiple configuration and GTO series connection, the inverter capacity is increased effectively. High conversion efficiency is obtained by using low-loss snubber circuits for GTOs. It is confirmed that the low-loss snubber circuits using energy recovery units (ERUs) have good performance in pulse-width modulated (PWM) operation. High-energy recovery efficiency is obtained, especially in leading operation (turn-on operation when freewheeling diodes conduct). These snubber circuits have superior ability for clamping overvoltage at GTO turn-off. A 2750 kVA inverter with low-loss snubber circuits using high-power GTOs has been fabricated and evaluated. >

This paper traces the development of three-phase induction motor controls using the Semikron advanced integration (SKAI) power electronics system. The SKAI was developed for hybrid and electric vehicles and integrates all the components of a three-phase inverter. As such, it promises to deliver significant cost savings. The SKAI utilizes a digital signal processor (DSP) controller. However, Semikron does not supply the necessary software for the DSP controller. The DSP used in the controller is manufactured by Texas Instruments. Texas Instruments provides an array of DSP programming utilities. This paper discusses aspects of programming and testing the DSP controller

With the application of an energy rebound circuit for the pulsewidth modulation (PWM)-controlled rectifier, an improved current source gate turn-off thyristor (GTO) inverter system capable of producing sinusoidal inputs and outputs is presented. The energy rebound circuit in the inverter is used to turn off the thyristors in the rectifier for applying PWM control techniques and also to clamp the spike voltage produced in the inverter circuit. The principles and circuit operations of this system are described in detail, and requirements for PWM control of the rectifier are investigated. The conditions for satisfying the requirements of the energy rebound circuit are analyzed by experimental and theoretical methods. The PWM-controlled current source GTO inverter system is used to drive an eight-pole 400 Hz 5.5 kW induction motor. Analytical and experimental results, as well as the characteristics of the motor drives, are given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

New devices that are challenging the silicon-controlled rectifier are considered. Among them are the high-power bipolar-junction transistor (HPBT), the power MOS field-effect transistor (MOSFET), the gate turnoff (GTO) thyristor, and the insulated-gate bipolar transistor (IGBT), sometimes called a conductivity-modulated field-effect transistor (COMFET). Also important are the static-induction or short-channel junction-effect transistor, and its cousin, the static-induction thyristor. Applications for these devices are outlined, and their characteristics are briefly sketched. The use of MOSFETs in automobiles and IGBTs for motor drives is examined in more detail. Packaging issues are discussed.

A system for measuring the subthyristor parameters of GTO (gate-turn-off) thyristors is presented. With the aid of a personal computer the gate breakdown voltage and leakage current, the turn-on and turn-off times, and the forward voltage drop of each subthyristor can be automatically measured, stored, and statistically evaluated. The cumulative frequency and distribution of the gate breakdown voltages on an ordinary pellet are discussed. A further example shows the distributions of gate breakdown voltage and turn-off times on a pellet with a doping inhomogeneity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Gate turn off thyristor (GTO) gating circuits, especially off-gating circuits, are the most important for reliable operation of GTO equipment. This paper describes a new gating circuit for high power GTO of 600A class. The off-gating circuit can provide a negative pulse of 200A with its rate of rise of 30A/us. Its power dissipation decreases to 20 percent of a previous type. The on-gating and negative bias circuits are also described.

The waveforms and power factor of an ordinary line-commutated thyristor inverter can be improved by adding one bypass GTO (gate-turn-off) thyristor and a small AC filter unit. Possible transitions between the switching states of the inverter are investigated on the basis of instantaneous voltage and current vectors. The extended freedom from adding the GTO is clearly shown. Restrictions for the pulse width-modulation (PWM) pattern are also shown, and an example pattern is deduced. A criterion for the design of the AC filter parameters is given. The validity of the method is confirmed by simulation and experimental results. >

The authors present the description, steady-state modeling, and filter design of a double-inverter PWM (pulse-width-modulated) solid-state synchronous condenser (SSSC) for reactive power compensation. The proposed scheme integrates the advantages of PWM selective harmonic elimination modulation (SHEM) and harmonic cancellation by transformer connection (HCTC) to minimize the filtering requirements. The key feature of the proposed double-inverter SSSC system is the low-switching frequency of the PWM pattern, which allows the utilization of high-power GTO (gate turn-off) thyristors (f/sub sw,max/=420 Hz). A series of PWM switching patterns in the low-switching frequency range that is most suitable for high-power GTO thyristors is presented. The performances of the SSSC for these PWM patterns are compared. Other figures of merit for the system, such as filter design and system derating, are discussed. The steady-state waveforms of the compensator current for single- and double-inverter SSSC systems are compared.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In conventional buck-boost converters, the output voltage is inverted. Hardware circuitry or microcontrollers are used to trigger a switch in the converter. In the proposed study, a non inverting buck-boost converter is implemented for PV system. The Pulse width modulation (PWM) signals for two MOSFETS in the converter are generated by DSP TMS 320 2808. Depending on the solar panel input, buck-boost converter charges the battery. The DC loads are driven from the battery. The load voltage and load current are sensed and compared with the reference voltage. Hardware circuitry or microcontroller is less accurate and using these systems the solar energy cannot be efficiently converted into electrical energy. In industry and commercial applications Digital Signal Processor (DSP) is used for automation. The same DSP can be used to generate PWM signals so as to get maximum electrical energy from solar energy. The DSP is more accurate and this works in real-time scenarios. The efficient utilization of resources such as DSP is achieved in the proposed study as the same DSP is used for generating PWM signal. In the proposed study, PWM signals are generated from DSP depending on load voltage and load current. The proposed work is better as compared to existing systems in terms of line and load regulation, efficiency, accuracy and speed as validated by experimental results.

In this paper, a pulse width modulation (PWM) control approach to speed trackong control is developed for the three-phase induction motor in electric vehicles.The PWM technique is amployed to design controllers.By incorporating the three-phase bridge recifier into the motor based on the PWM technique ,the PWM control approach is developed.The proposed control method is able to overcome the disadvatage of the motor in the traditional design procedure.In addition,it is proved that the tracking error converges to a small neighborhood of the all origin and all the closed-loop signals are bounded.The results of the MATLAB simulation illustrate the effectiveness of the proposed approach.

Programmable smart fast gas chromatograph and open probe controller

In this paper, a Digital Signal Processing (DSP) control system which is used in the multiple degree-of-freedom (DOF) giant magnetostrictive smart structure (GMSS) is proposed. The control system includes two parts - DSP Card and analog circuit through which DSP Card can get the detection signal and output control signal to giant magnetostrictive actuator (GMA). A adaptive least mean-square (LMS) control algorithm is embedded in DSP Cardpsilas Flash Memory for controlling GMSS to weaken the micro-vibration outside. Work flow and control approach of the GMSS with the DSP control system are introduced. The experiment results indicate that the DSP control system in this paper has better control precision and real-time property, and the damping effect is up to 20-30 dB.

The electrothermal behavior of a 1200V-30A gate turn-off (GTO) thyristor operating in its electrical circuit has been studied using two-dimensional (2D) simulation tools. The program realized for this purpose uses a combination of Silvaco tools and takes into account the thermal environment of the GTO. It was validated by direct experimental measurements. The studied GTO is a silicon device with a symmetrical doping profile (N+PN−P+). It operates in a dc-dc converter at a 400 Hz commutation frequency, its conduction time is in the range of 0.05–0.25 ms. The thermal environment of the device is reproduced by including its thermal parameters and those of its package in the calculation, the simulation accounts, then, for all the thermal generation and conduction in the device. The simulation program was validated by comparing the electrical parameters (anode and gate currents, anode–cathode voltage, and dissipated power) of the GTO, obtained in the same operating conditions, by both simulation and direct measurements. The transient behavior of the GTO during its turn-off at a nanosecond scale was then obtained. We first obtained the 2D time-dependent distribution of most of the internal electrical parameters (carriers, current density, …); then we obtained the 2-D time-dependent distribution of temperature inside the GTO.

The authors review the fundamental mechanism by which rotating electrical machines develop torque and draw conclusions as to which configuration offers inherent advantages in this regard. Development of a DC machine with a continuous armature winding where gate turn-off (GTO) thyristors replace the traditional copper-segment-carbon-brush commutator is described. Operation of a separately excited machine with 12 armature tapping points and 18 GTO thyristors is demonstrated, and waveforms are presented to illustrate the switching duties involved. >

4H-SiC gate turn-off (GTO) thyristor offers extraordinary advantages over its counterparts in handling ultra-high voltage electric power conversion applications because of its relatively low forward voltage drop at high conduction current density. Besides, though the SiC thyristors never suffer from long carrier liftime induced large switching loss like Si thyristors, the peak temperature rise rather than dynamic avalanche breakdown is blamed for the safe operation area (SOA) failure, making further reduction of power loss in SiC GTOs even more important. In this paper, a 20 kV SiC GTO with direct carrier extraction access to its drift region (DA-GTO) is investigated to explore the benefit this structure could bring for SiC thyristors, namely achieving smaller switching loss and/or potential larger SOA with slight sacrifice in forward voltage drop at high current. The structure is formed by interleaved P+ ion implantation into part of the thin N-injector layer based on conventional 20 kV SiC GTO. The SiC DA-GTO operates in BJT mode at low current, and in GTO mode with low forward voltage drop at high current. During turn-off process, it offers a direct current path to quickly sweep out the excess carriers in the P-drift region, thus speeds up the turn-off process and decreases the turn-off loss. Simulation results show that its turn-off loss reduces by 37.4%, contributing to 12.6% reduction in total power loss, compared with SiC GTO. Therefore, SiC DA-GTO is a very promising choice for next-generation power conversion systems.