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This paper presents a new dual loop control using novel vector product phase locked loop (VP-PLL) for a high power static var compensator (SVC) with three-level GTO voltage source inverter (VSI). From a simple dq-axis equivalent circuit obtained by circuit DQ-transformation method, steady-state analysis is achieved for maximum controllable phase angle αmax per unit current between AC source and switching function of inverter. In addition, the system parameters L and C are designed and thus transient analysis is made for open-loop transfer function. This paper proposes software VP-PLL for more accurate α control than conventional hardware PLL because αmax becomes very small in high power SVC. Therefore, the overall controller has dual loop structure of inner VP-PLL for synchronizing the phase angle with AC source and outer Q-loop for compensating reactive power of load. Finally, the usability of the proposed control method is verified through the experiment of 100kvar power capacity with both stand alone a...

A soft switching quasi-parallel resonant DC-link (QPRDCL) inverter with improved PWM capability has been recently presented. The circuit has the minimum voltage stress of the devices and provides the flexibility of selecting the on/off instants of the resonant link, resulting in improved PWM capability. In this paper, the operational principles and the detailed analysis of the QPRDCL inverter are presented for the resonant components design and the inverter control. An SVPWM with optimal vector sequence suitable for the QPRDCL inverter is also presented through the comparisons among five different modified space vector PWM (SVPWM) techniques classified by the voltage vector sequences. The performance of the selected optimal SVPWM is verified by the experimental results.

This paper proposes a new control method of a static var compensator (SVC) with a three-level inverter, to control reactive power with fast dynamics while maintaining the DC side capacitor voltage constant. First, using the circuit DQ-tranformation, a general and simple model of SVC with a three-level inverter is obtained, and DC and AC analyses are carried out to characterize the open-loop system. Based on the transfer function matrix of the system, modulation index control for reactive power compensation and phase angle control for DC side voltage regulation are designed. By inserting a feedforward path to the voltage regulation loop the modulation index is successfully decoupled from the capacitor voltage, whereby fast dynamics are achieved. The experimental results confirm the theoretical analyses and control method.

Comparative studies between harmonic elimination and optimal PWM strategies are given for high power three-level inverter feeding an induction motor. An effective PWM map construction method based on the valid region on the frequency modulation index plane is suggested. Thereby, an optimal map including asynchronous space vector PWM, harmonic elimination and optimal PWM method is generated covering all of the low, middle and high modulation index regions. The PWM map was designed for 1 MVA rated general purpose GTO inverter and implemented with a digital signal processor. Experimental results are presented for 10 kVA prototype. >

New current-source type base drive schemes are proposed using high frequency converters with zero voltage switching. Using these drives, the performance of a switching bipolar power transistor is enhanced: the transistor can be lightly saturated in accordance with the load condition because its base current can easily be controlled. The proposed circuits are very small and the efficiencies are higher than for conventional circuits. These base drive schemes are also easily extendable to drive multiple power transistors.

A recently proposed circuit P-Q transformation is used to analyze a three-phase controlled-current PWM rectifier. The DC operating point and AC transfer functions are completely determined. Most features of the power converter are clearly interpreted. They are: (1) the output voltage can be controlled from zero to maximum; (2) the system is equivalently an ideal current source in the steady state; (3) the system can be described as linear circuits; and (4) the input power factor can be arbitrarily controlled within a certain control range. >

A new control scheme named optimum quantum sequence control (OQSC) which always minimizes the output voltage ripple of the quantum series resonant converter (QSRC) for all possible sequences is proposed. This control scheme is so general that it is irrelevant to all circuit conditions such as magnitudes of circuit elements as well as input/output voltage so far as it is operating in the continuous conduction mode (CCM). Furthermore, the dynamic range of QSRC is much extended by the OQSC. This feature is verified by simulations and experiments with good agreements. >

A multilevel PWM voltage source inverter, especially a five-level one, is introduced to obtain a static var compensator (SVC) as a large scale power source. The multilevel inverter has many advantages, such as better utilization of the switching devices, lower switching frequency at each semiconductor switch and reduced harmonics. In this paper, the SVC with five-level inverter is modelled using circuit DQ transformation and completely analysed including DC and AC characteristics. It is also pointed out that the modulation indexes depend on the values of the DC side capacitors to meet the DC side voltage balancing, Finally, through the experimental results from a 5kVA SVC, the validity of the analyses and the feasibility of the var compensation system are shown for high power applications.

A soft switched space vector PWM inverter is developed using new parallel resonant DC-link (PRDCL). This PRDCL can operate on variable DC-link pulse position and width resulting in enhanced PWM capability, which is superior to other resonant DC-links. A new space vector algorithm is presented suitable for this PRDCL inverter. The suggested algorithm is able to eliminate narrow PWM pulses that impede DC-link operation. This PWM control, however, requires complex and precise timing sequences in relation to PRDCL operation, which is nicely solved by adopting a new programmed controller with a buffer and a programmable timer.

For the generalization of quantum resonant converters, new quantum resonant modules, which are a quantum series resonant module (QSRM) and a quantum parallel resonant module (QPRM), are proposed. The QSRM and QPRM are modeled as an equivalent inductor and an equivalent capacitor, respectively. The models of the proposed modules are useful in deriving the practical family of quantum resonant converters corresponding to the conventional PWM converters. The AC/AC quantum resonant converters are useful in high-performance applications. The concept of modules and the validity of the modeling are confirmed by the experiment. >

A soft-switched matrix converter is proposed using the zero voltage switching technique in some resonant pole inverters. A high operating frequency with safe and efficient switching improves the dynamic and spectral performances and simplifies the protection logics and snubber networks. Further, it can be implemented using simple analogue circuits, having similar transfer characteristics to those of the modern pulse width modulated matrix converters, such as maximum voltage transfer ratio and unity input displacement factor. Analyses, design and simulation results are presented to verify the operating principle.

A new zero voltage switching(ZVS) dc/dc converter is proposed, which provides ZVS conditions to secondary rectifying diodes as well as primary main devices. As a result of very low switching loss, the proposed converter can be operated at megahertz frequency range. The operational principle and analysis are described and verified with 150 watts prototype converter in the frequency range around a megahertz.

The authors propose a novel soft switching DC/DC converter with combined zero-voltage and zero-current switching. The power transfer mechanism of the proposed converter is different from that of such resonant-type converters as the resonant converter and quasi-resonant converter. The VAr (volt-ampere reactive) rating of the resonant capacitor of the proposed converter is very small compared with that of the resonant-type converter. The applied voltages to all the devices are limited to the supply voltage. This converter can operate in both constant and variable frequency with simple control. The basic operation of the proposed converter is described. Simulation was performed at 100 kHz and several-kilowatt output power, and experimental results are presented. >

There is a continuous demand for improvements in the quality of switching power devices, such as higher switching frequency, higher withstand voltage capability, larger current-handling capability, and lower conduction losses. However, for single-conduction-mechanism devices (SCRs, GTOs, BJTs, FETs), possessing all these features is probably unrealizable for physical reasons. An attractive solution appears to be double-mechanism devices, in which the features of both a minority carrier device (BJT or SCR) and a majority carrier device (MOSFET) are embedded. Both IGBTs (insulated-gate bipolar transistors) and MCTs (MOS-controlled thyristors) belong to this family of double-mechanism devices and promise to have a major impact on converter circuit signs. The authors deal with the major features of these two devices, pointing out those that are most critical to the design of power converter topologies. In particular, the two devices have been tested both in a chopper and in two resonant link converter topologies, and the experimental results are reported. >

Quantum parallel resonant converters (QPRCs), a dual converter of quantum series resonant converters (QSRCs), and a subset of parallel resonant converters (PRCs) operating on zero-voltage switching conditions are modeled. It is shown that the QPRC can be operated as a Cuk converter with an equivalent capacitor, or as a buck or buck-boost converter with an additional equivalent capacitor. The approach to modeling these converters is verified by analysis and simulation results for the PRC. DC and AC characteristics of the quantum PRCs can be obtained from these models. Therefore, the QPRC can be designed to be similar to the QSRC, i.e. to be controlled with closed-loop feedback and to have advantages such as low device switching stress, reliable high-frequency operation, low electromagnetic interference, etc. >

An electronic ballast for fluorescent lamp lighting using a novel resonant inverter is proposed. The electronic ballast has high efficiency, light weight, and small size because the resonant inverter operates at high frequencies with low switching losses. The inverter output power can be continuously controlled by regulating the LC resonant tank energy of the resonant inverter. The lighting system using this resonant inverter has the prominent features of high efficacy, low flicker, low noise, wide dimming range, and soft starting. The basic operating principle of the proposed inverter and the dimming control scheme are described, and experimental results are presented. >

A model based on practical switches with finite turn-on, turn-off, delay, storage, and reverse recovery times is proposed. The effects of switching on the state equation, system stability, DC gain and efficiency are shown for the boost, buck, and buck-boost converters. The effect of current-based switching-time variation on system stability effect, and the effect of average duty cycle variation on system stability is considered. DC gains of the boost and buck-boost converters are shown to be greatly degraded by switching loss. It is also shown that no additional resistance is generated by switching, in contradiction to previous work. It is found that the buck converter is superior to the others from the viewpoints of systems stability and DC gain, and the efficiencies of all the converters are maximized when the DC gain is close the unity. Previous results are improved and unified using state-space modeling. Analysis results are very simple in spite of the complex switching waveforms. This modeling approach is believed to be very useful for the high-frequency or high-power applications where switching effects become dominant. >

A soft switching power converter topology for high frequency (HF) AC/DC/AC power conversion which synthesizes the sinusoidal output voltages and results in a considerable reduction of acoustic noise is proposed. The converter achieves soft switching without increasing the voltage or current ratings of devices and has the capability of HF and four quadrant operation. HF operation by soft switching provides several advantages such as high power density, low electromagnetic interference and high dynamic performance. The voltage stresses and the current stresses in this converter are limited to the supply voltage and the link current by the operation of a current free-wheeling circuit, and thus the VA ratings of devices are reduced to those of the hard-switched inverters. Simulation results are presented to verify the operational principle. >

A high-performance induction motor (IM) drive which is different from field-oriented control (FOC) is presented. In this drive, the rotor flux and the stator current are simultaneously controlled. The drive has the characteristics of good dynamics and fast transient response. Implementation of this drive is very simple compared with the FOC. Although the drive is robust against the rotor resistance variation, a rotor resistance compensation method for controlling the output torque accurately is presented. Simulation results show that the drive scheme can be used for applications requiring good dynamic performance. >

A zero voltage switching (ZVS) PWM power converter family is obtained by using a new ZVS PWM module (ZPM) with a saturable inductor which prevents the diode junction capacitors and the commutation inductor from resonating. The new converters show almost all the characteristics of the conventional PWM converters. A boost ZVS PWM converter is applied to a power factor correction circuit. It operates on a continuous conduction mode. Experimental results for output power of 1 kW are presented. >

The circuit D-Q transformation is used to analyze a three-phase, current-source, pulse-width modulated (PWM) rectifier. The DC operating point and AC transfer functions are completely determined. Most features of the converter are clearly interpreted. The output voltage can be controlled from zero to maximum. The system is equivalently an ideal current source in the steady state and can be described in terms of linear circuits. The input power factor can be arbitrarily controlled with a certain control range. >

A multilevel pulse-width-modulation (PWM) voltage-source inverter is connected to a static volt-ampere-reactive (VAr) compensator (SVC) as a large-scale power source. The SVC can be directly connected to AC mains of 6600 V, allowing full utilization of semiconductor devices like gate turn-off thyristors (GTOs). The voltage balancing condition of the DC slide capacitors is identified based on the fundamental circuit modeling of the inverter, and a five-level PWM is used to meet the condition. Owing to the multilevel approach, a low distortion in the input currents results and filter size thus is minimized. To confirm the validity of the fundamental circuit modeling of the SVC system with a five-level inverter, the system was simulated using commercial simulation packages. >

Five different topologies for AC choppers are studied. Among them are the soft switching power converters ZCS (zero current switching) QSRC with three switches, half-bridge ZCS QSRC, ZVS (zero voltage switching) step down converter with two switches, and ZVS step-down converter with small current ripple. They are applicable to AC choppers requiring four-quadrant operation. The two-step driving-down converter has the lowest current ripple and acceptable switching loss and is the most suitable for implementing a small, lighter, and more economical high-power system (>1 kVA). >

A soft-switched space vector pulse-width-modulated (PWM) inverter is developed using a novel parallel resonant DC link (PRDCL). This PRDCL can operate on variable DC link pulse position and width, resulting in enhanced PWM capability, which is superior to that of other resonant DC links. A space vector algorithm suitable for this PRDCL inverter is presented. The algorithm eliminates narrow PWM pulses which impede DC link operation. This PWM control, however, requires complex and precise timing sequences in relation to PRDCL operation, which is accomplished by adopting a new programmed controller with a buffer and a programmable timer. >

A three-level GTO inverter topology is presented. This new power circuit includes many advantages compared with the conventional three-level GTO inverter. The main advantages are snubberless and good device utilization by using a dual quasi-resonant DC-link which guarantees the complete zero voltage switching of the inverter GTOs. This three-level GTO inverter can be operated with lower switching loss at higher switching frequency with complete zero voltage inverter switching. >

A new type of dual output zero voltage switched (ZVS) DC/DC power converter is proposed. One output is dependent on the effective duty ratio and the other is largely dependent on the switching frequency. Two completely regulated outputs are obtained with only one bridge circuit by combining the different configurations of secondary output. Using ZVS technique, switching loss can be reduced to quite low at several hundred kHz. >

An offline zero-voltage-switching (ZVS) PWM AC-DC power converter for single-stage preregulation in distributed power systems is proposed. The converter provides both input power factor correction and direct conversion from a 110-220-V AC line to a 48-V DC bus with a single power stage. Compared to the conventional two-stage approach (a boost rectifier followed by an offline DC-DC step-down converter), the proposed approach reduces the loss of one power stage. A new simple auxiliary circuit provides the zero-voltage-switching (ZVS) condition to all semiconductor devices without imposing additional voltage and current stresses and loss of PWM capability. The operational principle, analysis, control of the proposed power converter, and simulation results for a 1-kW prototype are presented. >

This paper presents a new dual loop control using novel vector product phase locked loop (VP-PLL) for a high power static VAr compensator (SVC) with three-level GTO voltage source inverter (VSl). Through circuit DQ-transformation method, a simple DQ-axis equivalent circuit is obtained. From this, DC analysis is carried out to obtain maximum controllable phase angle /spl alpha//sub max/ per unit current between the three phase source and the switching function of the inverter, and AC open-loop transfer function is given. Because /spl alpha//sub max/ becomes small in high power SVC, this paper proposes VP-PLL for more accurate a control. As a result, the overall control loop has dual loop structure, which consists of inner VP-PLL for synchronizing the phase angle with source and outer Q-loop for compensating reactive power of load. Finally, the validity of the proposed control method is verified through the experimental results.

Rotor time constant is essential for high performance motor control in the induction motor. A simple and exact measurement method of rotor resistance and rotor time constant of induction motor is proposed. A DC current is injected to the magnetizing inductance, and then the magnetizing current is discharged to the rotor, so that the voltage is taken at the stator. Then the measured stator voltage has information of rotor time constant as a function of magnetizing current. In this paper, rotor time constant obtained from conventional method and the proposed method are compared. The accuracy of the measurement is tested with a vector controller by a linear relation between the input torque command and output torque at steady state. >

In this paper, a new type of PWM series resonant converter is proposed. One pole of the proposed converter is switching at zero-current and the other is switching at zero-voltage. By introducing an auxiliary inductor, zero-voltage switching is possible even at no load. The proposed converter is suitable for a high-voltage DC/DC converter because the voltage stresses of switching devices are minimized. >

A small size and high efficiency base drive scheme using a high frequency partial resonant converter with zero voltage switching (ZVS) is proposed. By using this base drive, the performance of switching power transistors is enhanced to some extent because the transistor can be lightly saturated in accordance with the load condition owing to easy control capability of transistor base current. >

A modified output control scheme for the series resonant converter (SRC) is proposed. In this scheme, quantized output voltage is obtained by quantum duty control and one last unit voltage is continuously adjusted by phase angle control during a half resonant cycle period. The proposed control method suggests a way to eliminate the stepped discontinuity problem in the output voltage of quantum control without degrading the performance. Based on the steady-state analysis, an optimum quantum sequence with greatly reduced output voltage ripple is given. >

The modified DC-link (MDCL) converter generating sinusoidal output voltage solved the drawbacks of soft switching converters, such as high voltage stresses of devices and/or many device counts. However, it also has problems such as the high peak device current and a wide variation of switching cycle interval. An improved soft-switching AC/DC/AC converter based on a high-frequency link is proposed to solve these problems. By introducing a current freewheeling circuit, it separates the main power flow from the resonating circuit during the commutation interval. As a result, the peak current is limited to around the link current and the switching cycle interval is controllable. Furthermore, the VA ratings of the devices are considerably reduced. Therefore, this converter combines the desired features of the MDCL converter with its improvements. >

A novel zero voltage switching (ZVS) voltage source inverter is presented to overcome the main problems of the resonant DC link type inverter with discrete pulse modulation, such as the subharmonic problem and high voltage stress (1.3 approximately 1.8 p.u.). The proposed ZVS inverter adopts a parallel resonant DC link and has pulsewidth modulation capability with minimum device voltage stress (1.0 p.u.). In addition, the design and control of the proposed inverter are fairly simple. The operational principle, a detailed analysis, and design procedures are described. A 7.5 kVA prototype inverter was implemented and tested with 20 kHz switching frequency. Experimental results verifying the principle of operation are shown. >

For generalization of the soft-switching-based quantum resonant converters including AC/AC conversion applications, a new concept of quantum resonant switches which include quantum series resonant switches (QSRS) and quantum parallel resonant switches (QPRS) is proposed. The quantum resonant switches are modeled as an equivalent inductor for QSRS and equivalent capacitor for QPRS. The basic conventional PWM (pulse-width-modulated) DC/DC and AC/AC converters can be changed to the corresponding quantum resonant converters with the same global characteristics by replacing the link inductor or capacitor with the proposed QSRS or QPRS. Thus, the conventional modeling and design methods can also be applied to quantum resonant converters. In this procedure, a number of useful quantum resonant AC/AC converter which can improve the characteristics of the high-frequency DC-link AC/AC converters are proposed. Experimental verifications of the modeling of the quantum resonant switches and the topologies and basic operations of the proposed quantum resonant DC/DC and AC/AC converters are presented. >

This paper presents a new active power filter connected in series with a bank of capacitors having no tuned filters and no resonance problem related with harmonic loads. A capacitor of appropriate small size is determined considering much small power capacity of the converter compared with load power. Through frequency analysis of the system, a dual loop controller is designed for eliminating harmonics of load current and reducing the fundamental voltage component of the converter. Finally, the performance of the presented scheme is confirmed using simulation with 10 kVA 6-pulse load and experimental results with 1 kVA 6-pulse load.

This paper proposes a new control method of static VAr compensator (SVC) with a three-level inverter to control reactive power with fast dynamics while maintaining DC side capacitor voltage constant. Firstly, using the circuit DQ-transformation, a general and simple model of SVC with a three-level inverter is obtained, and DC and AC analyses are carried out to characterize the open-loop system. Based on the transfer function matrix of the system, modulation index control for reactive power compensation and phase angle control for DC side voltage regulation are designed. By inserting feedforward path to the voltage regulation loop the modulation index is successfully decoupled from the capacitor voltage whereby fast dynamics are achieved. The experimental results confirm the theoretical analyses and control method. >

A novel CMOS Variable Gain Amplifier (VGA) with high frequency and high dynamic range is proposed. It has a controllable gain range from -45 dB to +45 dB by external control voltage as well as enhanced operating frequency up to 200 MHz. It is fabricated in 0.35 /spl mu/m CMOS technology with the core area of 580 /spl mu/m/spl times/660 /spl mu/m. It consumes only 10.8 mA at 3.3 V supply voltage.

A new CMOS Double-Upconverter (DUC) with half-LO for a DTV (Digital TV) tuner is proposed. It converts a wide-band input video RF signal spanning from 48 MHz to 810 MHz to an IF of 932 MHz with half local oscillator frequencies from 490 MHz to 871 MHz. The proposed architecture reduces the local oscillator frequency to half, which enables the integration on a single chip and reduces the overall power consumption. It also makes the image component low with its architectural property devised on the basis of the Weaver architecture. It is implemented with 0.8 /spl mu/m CMOS technology modified for RF applications.

Describes the design of 2 GHz LC-oscillator for IMT-2000 frequency band application. The LC-oscillator has a simple automatic swing control circuit for providing constant output power to mixer and prescaler. Total circuit consists of oscillator core, buffer, bandgap reference and drive amp. The oscillator core consumes 1.3 mA. A frequency tuning range is about 360 MHz. The output power of the LC-oscillator varies within 1.1 dBm. This chip is implemented in 60 GHz SiGe BiCMOS process by ST Microelectronics. Total power consumption is 31.5 mW at a 2.7 V single power supply.

The production of $\phi$ mesons in the reaction $e^{+}p \rightarrow e^{+} \phi p$ ($\phi \rightarrow K^{+}K^{-}$) at a median $Q^{2}$ of $10^{-4} \ \rm{GeV^2}$ has been studied with the ZEUS detector at HERA. The differential $\phi$ photoproduction cross section $d\sigma/dt$ has an exponential shape and has been determined in the kinematic range $0.1, Comment: 23 pages, including 6 post script figures

The static and dynamic characteristics of a practicable step-up nine-switch matrix convertor under the control strategy proposed by Venturini are analysed fully by the recently presented circuit DQ transformation technique and signal flow graphs. The step-up nine-switch matrix convertor consists of nonideal voltage and current sources, such as occur in practical inductance and capacitance filters. Several static and dynamic features of the convertor, such as steady-state input/output voltage gain, input power factor and transient response, are predicted analytically and verified by computer simulations. The signal flow graph is adopted to solve the complex fourth-order equivalent convertor and thus the nine-switch matrix convertor is analysed fully in explicit form.

The production of φ mesons in the reaction e+p → e+φp (φ → K+K−), for 7 Q 2 GeV 2 and virtual photon-proton centre of mass energies (W) in the range 42–134 GeV, has been studied with the ZEUS detector at HERA. When compared to lower energy data at similar Q 2, the results show that the γ ∗ p → φp cross section rises strongly with W. This behaviour is similar to that previously found for the γ ∗ p → ϱ 0 p cross section. This strong dependence cannot be explained by production through soft pomeron exchange. It is, however, consistent with perturbative QCD expectations, where it reflects the rise of the gluon momentum density in the proton at small x. The ratio of σ(φ) σ(ϱ 0 ) , which has previously been determined by ZEUS to be 0.065 ± 0.013 (stat.) in photoproduction at a mean W of 70 GeV, is measured to be 0.18 ± 0.05 (stat.) ± 0.03 (syst.) at a mean Q 2 of 12.3 GeV2 and mean W of ≈ 100 GeV and is thus approaching at large Q 2 the value of 2 9 predicted from the quark charges of the vector mesons and a flavour independent production mechanism.

Jet photoproduction, where the two highest transverse energy ($\ETJ$) jets have $\ETJ$ above 6 GeV and a jet-jet invariant mass above 23~GeV, has been studied with the ZEUS detector at the HERA $ep$ collider. Resolved and direct photoproduction samples have been separated. The cross section as a function of the angle between the jet-jet axis and the beam direction in the dijet rest frame has been measured for the two samples. The measured angular distributions differ markedly from each other. They agree with the predictions of QCD calculations, where the different angular distributions reflect the different spins of the quark and gluon exchanged in the hard subprocess., 20 pages including 4 figures

Detailed analysis and optimum design of the commutating circuit of the recently proposed DC-side commutated current-source inverter are given. Analysis was performed for each topology mode during a step transition interval under certain assumptions and using various normalised quantities. Using the analysis results, optimum design of the commutating circuit was studied with an aim to maximising the turn-off time with a minimum commutating energy. Experimental results showed reasonably good agreement with the theoretical results.