Abstract: A bypass control section (6) maintains a bypass switch (5) in the ON state during the period when a battery voltage (Vi) is higher than the output voltage (Vo) to an external load (L). Upon falling of the output voltage (Vo) at a desired voltage (ET), a converter control section (4) starts switching control at once, and a step-up chopper (3) promptly starts boost operation. The bypass control section (6) maintains the bypass switch (5) in the ON state from the start of the boost operation of the step-up chopper (3) until the match between the battery voltage (Vi) and the output voltage (Vo).

Abstract: The modelling of an electronic load controller (ELC) for a self-excited induction generator (SEIG), used for power balancing at varying consumer load as required for stand alone micro-hydel generators driven by uncontrolled turbines, is presented. The implemented ELC consists of a rectifier-chopper system feeding a resistive dump load whose power consumption is varied through the duty cycle of the chopper. While the dynamic modelling of the SEIG is carried out using d-q variables in a stationary reference frame including magnetic saturation, the ELC is modelled through circuit concepts incorporating a switching function. Both the modelling and control technique of the ELC-SEIG are validated through simulated and experimental results.

Abstract: 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.

Abstract: PROBLEM TO BE SOLVED: To provide a power supply circuit which can limit an excessive input current flowing when it is started, additionally can make output voltage rise up instantaneously to the desired voltage even in the case that step-up action repeats start/stop in accordance with a PMW signal. SOLUTION: A drive means, receiving a control signal with a first/second condition alternately appearing to operate step/up action for stepping up output voltage by changing over a switching element when the concerned control signal is placed in the first condition, on the other hand so as not to operate the concerned step/up action when the concerned control signal is placed in the second condition, and a soft start circuit processing a soft start for loosening a rise up of the output voltage by the rise/up action, are further provided, the soft start circuit is made the power-supply circuit of step/up chopper regulator type which supervises a level of the output voltage and a condition of the control signal additionally processes the soft start only by the prescribed timing in accordance with the concerned supervising result. COPYRIGHT: (C)2007,JPO&INPIT

Abstract: A method of voltage harmonic elimination in a pulse-width modulated AC/AC voltage converter using genetic algorithms (GA) is proposed. The output voltage of the AC chopper with k pulses per half cycle is written in terms of switching angles using Fourier series, and the best switching angles are identified with the dual objectives of harmonic elimination and output voltage regulation. The problem is redrafted as an optimisation task, and a solution is sought through GAs. For performance comparison of GAs, other optimisation methods such as Rosenbrock's rotating coordinates method, the random search method and the Newton-Rasphson method are also applied to the present problem. Comparison shows that the genetic algorithm method is on a par with conventional optimisation methods. In addition, the GA approach has several advantages, such as a reduced computational burden, faster convergence and guaranteed global optima in most cases. The theoretical findings are verified through experimental results.

Abstract: A transformer-less inverter in which the inverter is composed of a DC inverter which initially converters the solar generator DC voltage into a symmetrical voltage relative to earth potential, and a chopper which generates controlled AC voltage pulses for regulating a sine-wave network feed current.

Abstract: The paper presents a single-crystal silicon (SCS)-based, integrated 3-axis accelerometer fabricated using a post-CMOS micromachining process. This new CMOS-MEMS process provides monolithic integration of electronics and SCS microstructures, and electrical isolation of silicon. By employing a unique vertical sensing mechanism, 3-axis acceleration sensing is achieved with a single proof mass. The symmetric structures and fully differential configuration of all the sensing electrodes can greatly reduce the cross coupling among the 3 axes. By sacrificing one interconnect metal layer, the silicon undercut of the sensing comb fingers is minimized, resulting in much higher sensitivity with the same device footprint. A wet Al etching process was also developed to remove the top Al layer without attacking the Al layers exposed from the sidewalls of the multilayer Al/oxide stacks. A two-stage, open-loop, continuous time chopper stabilized amplifier is integrated on the chip.

Abstract: The present invention provides for an improved electromagnetic radiation detector having a micromachined electrostatic chopper/shutter device. The MEMS flexible film chopper/shutter device provides reliability, efficiency, noise reduction and temperature fluctuation compensation capabilities to the associated electromagnetic radiation detector. An electromagnetic radiation detector having an electrostatic chopper/shutter device includes a detector material element and flexible film actuator overlying the detector material layer and moveable relative thereto. The flexible film actuator will typically include an electrode element and a biasing element such that the actuator remains in a fully curled, open state absent electrostatic voltage and moves to a fully uncurled, closed state upon the application of electrostatic voltage. Arrays that incorporate a plurality of electromagnetic radiation detectors and/or electrostatic shuttering devices are additionally provided for.

Abstract: A new CMOS chopper-stabilized differential difference amplifier (CHSDDA) that exploits the combination of chopper technique with differential difference amplifier is proposed, with advantages for use in instrumentation circuits requiring floating differential input and single-ended output. When configured as an instrumentation amplifier (IA), it operates as the analog front-end (AFE) for an electroencephalogram (EEG) recording system in integrated biomedical systems. The measurement results have shown that it achieves 1/f noise reduction, CMRR more than 120 dB (0-700 Hz), dc offset less than 16.5 /spl mu/V and current drain of 150 /spl mu/A at a 3 V single supply using a standard 0.6 /spl mu/m CMOS technology.

Abstract: There are provided an azimuth measurement device and its method for realizing an update of an offset calculated from the data acquired by azimuth measurement A geomagnetism output measured by a 3-axis magnetic sensor (10) is amplified by an amplification section (13) and input to an A/D conversion section (14) A chopper section (11) is arranged for switching the terminals for driving an X-axis magnetic sensor (2), a Y-axis magnetic sensor (3), and a Z-axis magnetic sensor (4) and applies drive voltage output from a drive power source section (12) to the X-axis magnetic sensor (2), the Y-axis magnetic sensor (3), and the Z-axis magnetic sensor (4) The output amplified value amplified by the amplification section (13) is converted from an analog signal to a digital signal by the A/D conversion section (14) and then is input to a sensitivity/offset correction calculation section (16) Output data from this sensitivity/offset correction calculation section (16) is input to an azimuth calculation section (20) and the corresponding azimuth information is output A reliability information calculation section (19) outputs reliability information

Abstract: In a chopper circuit, output power is controllable with a direct current power source as a power source, and a smoothing capacitor is connected between output terminals of the chopper circuit. A polarity inversion circuit applies an alternating voltage to a high pressure discharge lamp with a voltage across the smoothing capacitor as a power source. The output power of the chopper circuit and an inversion frequency of the polarity inversion circuit are controlled by a control circuit based upon a terminal voltage of the smoothing capacitor, which is detected by a voltage detecting circuit. In the control circuit, a switch voltage is set for defining a range of voltages detected by the voltage detecting circuit, and the inversion frequency is changed in plural stages according to the magnitude relation between the detected voltage and the switch voltage. The inversion frequency corresponding to electric power applied to the high pressure discharge lamp is set with respect to each range of lamp voltages, to thereby inhibit occurrence of an arc jump.

Abstract: A system and method for single phase AC power conversion for delivery to a load of AC voltage less than or equal to the supply voltage. The system includes a high frequency chopper converter having a series diode-switch assembly and a shunt diode-switch assembly. During intervals when the inductor carries current in phase with the power line, the diode-switch assemblies are configured such that the system operates as a buck converter, and during intervals when the inductor carries current out of phase with the power line, and power flow is reversed, the diode-switch assemblies are configured such that the system operates as a boost converter, boosting the load voltage to the power line voltage. Optionally, feedback is used to adjust the duty cycles of the diode-switch assemblies to shape the input and/or output current and to optimize performance of the load.

Abstract: The traction system of the subway VAL 206 is ensured by DC machines connected in series. A common chopper supplies the armature windings and a double-chopper supplies the field windings. Another power structure is suggested in order to increase performances during losses of adhesion. A specific control strategy is defined in order to obtain different torque on both machines despite their common armature current. An antislip control can thus be developed in applying the desired torque to each bogie at just the right time. This torque tracking strategy is validated on a 1.5 kW experimental set-up.

Abstract: This paper proposes an INTEL 8051 microcontroller based fuzzy controller for closed loop control of dc drive fed by dc/dc converter. The controller designed has two loops with an inner current controller and an outer fuzzy speed controller. Computer simulations evaluate (tested) the designed fuzzy controller. The controller is used to change the duty cycle of the converter and thereby, the voltage fed to the armature of the separately excited motor to regulate the speed. The simulated closed loop performance in respect of load variation and set speed change for both fuzzy controller and PID controller has been reported. The simulated results are compared with experimental results by using a buck converter with the fuzzy controller implemented in 8051-based embedded system. The entire system is found to be more advantageous and cost effective.

Abstract: A generating device that includes an AC/DC conversion unit having a rectifier circuit that rectifies an output of a magneto rotor and applies the output to a battery, and an inverter circuit that converts a voltage of the battery into an AC control voltage and applies the AC control voltage to an armature coil of the magneto generator, performs chopper control that controls switch elements of the inverter circuit so as to interrupt an output current of the magneto generator to control the output of the magneto generator when a rotational speed of the magneto generator is lower than a set speed, and performs drive control that applies the AC control voltage from the battery through the inverter circuit to the armature coil when the rotational speed becomes higher than the set speed, and changes a phase angle of the AC control voltage to control the output of the magneto generator.

Abstract: The plasma processing apparatus wherein the means for applying a high frequency voltage, which becomes a voltage waveform in which a positive constant voltage and a negative constant voltage alternate with each other at given cycles, is constituted by a DC power source and a switching circuit (a chopper circuit).

Abstract: A stable power supply apparatus in accordance with the present invention comprises a secondary battery, a bidirectional chopper circuit and a bidirectional converter, wherein the secondary battery, the chopper circuit and the converter are connected in this order in the direction from the secondary battery side to a system bus line side. The converter is formed of a wide-gap semiconductor device, more particularly, a wide-gap bipolar semiconductor device, and the instantaneous large-power operation capability of the wide-gap bipolar semiconductor device and the instantaneous large-power supplying capability of the secondary battery are utilized. For a short time during which the influence of an instantaneous drop is prevented, the converter is operated as a converter having capability exceeding the instantaneous large-power supplying capability of the secondary battery and having power capacity several times or more the rating of the converter.

Abstract: An advanced two-quadrant PWM controlled chopper type DC–DC power converter with lowered peak switch voltage stress, which is effectively used for parallel processing type small-scale UPS applications and utility interactive new energy interface distributed power supplies, is presented. In addition, a coupled inductor-assisted zero-voltage soft-switching PWM step-up chopper controlled type DC–DC power converter is also proposed and discussed. These two DC–DC converter circuit topologies are evaluated and compared on the basis of simulation and experimental results by a 1 kW 50 kHz breadboard setup using MOSFETs. The electromagnetic conductive noise characteristics of both converter circuits are also compared through experimentation.

Abstract: We present in this paper an implantable massively parallel cortical data acquisition system. The proposed embedded mixed-signal (analog/digital) processing units are intended to be integrated on one chip, which will be flipped and connected on the top of a microelectrode array. Each channel is composed of a Chopper stabilized (CHS) low-power front-end to remove the 1/f noise, and a mixed-signal compression module using an analog wavelet transform (WT) processor that covers the entire neural signals bandwidth. The proposed front-end is based on a new rail-to-rail preamplifier topology and its circuit simulation under 0.18 /spl mu/m CMOS process demonstrates a power dissipation less than 25 /spl mu/W per channel. The main application of this medical device is to record action potentials evoked by visual stimuli, but it can be useful for several other cortical recording purposes.

Abstract: In a high-pass (mirrored) integrator structure that employs chopper modulation, the input and output of the mirrored integrator are connected to the input and output ports of the operational amplifier, bypassing the chopper stabilization modulators. The mirrored integrator can be used in sigma-delta analog-to-digital converters.

Abstract: Power Electronics and Advanced Control technologies have made it possible to mitigate the power quality problems and maintain the operation of sensitive loads. Among power system disturbances, voltage dips, swells, and harmonics are some of the severe problems to the critical industrial loads. The static series compensator (SSC) is best suited to protect such loads against those disturbances. This thesis focuses on the control of the SSC in order to improve the transient and the steady-state responses and increase its injection capability. To mitigate voltage dips, the thesis proposes a vector-controlled based algorithm to improve the transient and the steady-state responses of the SSC. The developed algorithm incorporates both current and voltage controllers with an inner current loop and outer voltage loop. Thus, it is referred to as the Double Vector Control (DVC) algorithm. To cope with the unbalanced dips, a fast technique to detect the positive and the negative sequences is employed. Then the two sequences are controlled separately. Also the influence of the switching frequency on the controller performance is studied. A Software Phase Locked Loop with a PI controller is proposed in order to obtain the phase and the frequency information of the grid voltage. The tuning of the PI controller is made according to a developed criterion based on the frequency requirements of the loads. A number of power system events are studied and the behavior of the SSC is tested against each event. These events include short-circuit faults, capacitor-bank energizing, transformer energizing and load switching (linear and non-linear loads). Recommendations regarding the SSC operation for each event are given. The possibility of employing the SSC to mitigate swells/overvoltages is investigated. An overvoltage protection scheme is proposed, based on a combination of a dc resistor with a chopper and the SSC. The design equations of the dc resistor together with the chopper are provided. In order to mitigate the voltage harmonics, a new controller is developed and implemented. In the proposed controller, a moving average filter is implemented in the synchronous reference frame to extract the fundamental component of the measured voltages and currents. Also, an active filtering capability is added by using the resonant filters for the 5th and the 7th harmonics. After the extraction of the fundamental component, it is controlled by the DVC. The operation of the SSC under distorted utility conditions and voltage dips is discussed. The thesis also proposes two control techniques to charge the energy storage capacitor of the SSC. One of the techniques is based on a shunt diode rectifier, which is placed either on the load side or the grid side (both configurations are studied). The other technique exploits the voltage source converter of the SSC in combination with a proper control algorithm to charge the capacitor. A design guide for the energy storage capacitor is given. To minimize the required active power, this thesis discusses and compares four different compensation strategies: 1) Voltage Difference Compensation; 2) In-Phase Compensation; 3) Phase Advance Compensation; 4) Progressive Phase Advance Compensation. The effect of the load power factor on the different strategies is investigated. A control algorithm based on a combination of the four strategies is proposed taking into account the minimization of the active power and keeping the injected voltage within the ratings of the SSC. The validity of the developed controllers is verified by simulations and experiments. The simulation models are developed and implemented in the PSCAD/EMTDC package. A 10-kV SCC prototype is exploited to carry out the experiments with various load types.

Abstract: A chopper circuit (1) can control an output power using a dc power supply (E) as a power supply, with a smoothing capacitor (C1) connected between output ends of the chopper circuit (1). A polarity reversing circuit (2) applies an ac voltage to a high-pressure discharge lamp (La) using the ends voltage of the smoothing capacitor (C1) as a power supply. An output voltage from the chopper circuit (1) and a reversing frequency of the polarity reversing circuit (2) are controlled by a control circuit (4) based on the terminal voltage of the capacitor (C1) detected by a voltage detection circuit (3). The control circuit (4), with a change-over voltage set for limiting the range of a voltage detected by the voltage detection circuit (3), changes a reversing frequency in plurality of stages according to a magnitude relation between a detected voltage and a change-over voltage. A reversing frequency corresponding to a power input to a high-pressure discharge lamp is set for respective ranges of a lamp voltage to thereby prevent an arc jump from occurring.

Abstract: Electrolytic hydrogen offers a promising alternative for long-term energy storage of renewable energy (RE). A stand-alone RE system based on energy storage in the form of hydrogen has been developed at the Hydrogen Research Institute and successfully tested for automatic operation with an in-house designed control system and power conditioning devices. In this system the excess energy with respect to load demand is sent to the electrolyzer to produce hydrogen which, when properly stored, is available to the fuel cell to produce electricity when there is insufficient wind and solar energy with respect to load requirement. The RE system components have substantially different voltage-current characteristics, and they are integrated through the designed and developed power conditioning devices on a DC bus, which allows power to be managed between input power, energy storage and load. The DC-DC buck and boost converters are connected for power conditioning between the DC bus and the electrolyzer, and between the fuel cell and the DC bus, respectively. With respect to the energy level at the DC bus and the control strategy, the controller sends the conditioned signal (duty ratio) to the digitally controlled DC-DC converters for on/off operation, thus controlling the power flow to the electrolyzer and from the fuel cell. The converters' control is based on a chopper multiphase switching technique, which reduces the harmonics levels and ripples with a simple additional filter. The simulated and experimental results of the boost and buck converter operations are compared. Also the effect of duty ratio with respect to the number of cells in the converters has been studied for harmonic reduction. It has been found that the designed and developed DC-DC converters and the control system give effective power flow control with automatic operation of the system under different load conditions and with intermittent inputs from wind turbine generator and photovoltaic array.

Abstract: The design and evaluation of a MEMS-based chopper for optical measurements is reported. The overall dimensions of the chopper, including the microactuators and micromechanical suspension, are 1200/spl times/1200 /spl mu/m making it very compact. The comb-actuator driven chopper, designed for use in conjunction with fibre optics, has been fabricated in silicon-on-insulator material which has been back-etched to create an optical path through the thickness of the substrate. General electro-mechanical design considerations, including factors to minimise the side instability of the comb drive, are described. Finite element modelling (FEM) of the chopper is backed up by simple theoretical results, and the results from the theoretical work verify the findings from the FEM. Optical modelling of the chopper is also reported. Experimentally, the device was driven from 0-34 V DC to measure its static characteristics. For dynamic characterisation, the device was operated from 0-28 V AC and its fundamental resonant frequency was measured to be 3 kHz. Experimental evaluation of the device characteristics are shown to closely match the theoretical predictions.

Abstract: The invention relates to a serial voltage chopper comprising a pair of input terminal connectors (A, B) connected to an input direct voltage, a pair (P_O) of serial connected switches (SB, SH) which are connected to the input terminal connector (B) by the switch (SB), each switch being provided with a control input in order to simultaneously bring: the first switch into a conducting state by receiving a control signal on the input thereof, and the other into an non-connecting state by receiving a second signal complementary to the first signal on the control input thereof and a pair of output terminal connectors for supplying a charge. Said voltage chopper also comprises (K) additional pairs of series switches between the input terminal connector (A) and the switch (SH) of the pair (P_O), two switches of the same pair are in series connected through an energy recovery (Lr_i) coil, (K) input groups of Ni capacities of the same value each in series and (K) output groups (Gout-I of Mi) capacities of the same value in series each. The switches of said additional pairs are simultaneously controlled by additional control signals.

Abstract: PROBLEM TO BE SOLVED: To cope with high power while operating a power factor improving converter in a current discontinuous mode. SOLUTION: A choke coil L and a forward diode D are connected in series, and a choke coil L and a diode D are connected between a low-pass filter 103 that smoothes a rectified AC power supply 101 and an output smoothing capacitor 112. A plurality of unit chopper circuits composed of switching transistors connected between the point and the ground are connected in parallel, and each switching transistor is selectively set at the same frequency so that the terminal voltage of the output smoothing capacitor is constant, and The multi-phase drive is configured with drive signals having different phases so that the drive timings do not overlap. [Selection] Figure 1

Abstract: PROBLEM TO BE SOLVED: To construct a rational system in capacity, voltage and power supply efficiency in a power supply system for linking a private power generation system in which a storage battery facility is coupled to a plurality of types of private power generation facilities, to a commercial power supply. SOLUTION: A bus of a private power generation system is set to a DC line, the storage battery facility and the private power generation facility are coupled to the bus, a main facility having a generation power capacity is coupled directly to the DC line, and the other facility obtains voltage matching via a step-up or step-down chopper. When the storage battery or a private power generator which is larger than a power capacity requested by the system is used, in the storage battery facility or the private power generation facility, the number of cells of the storage battery or the number of serial connecting private power generators is reduced to be matched to the power capacity requested by the system, and a voltage difference with the DC voltage of the private power generation system is matched by the step-up/step-down chopper. The chopper is an opening/closing means for disconnecting the storage battery facility or the private power generation facility from the private power generation bus. COPYRIGHT: (C)2004,JPO

Abstract: In this paper, the problem of unbalance between the input voltages of a multilevel converter is analysed. To reduce the problem, particularly in braking operations, a feed-forward control method is proposed in the paper. The braking chopper is displaced between the LC chopper output filter and the load. It is switched on when the DC-link voltage becomes higher than a prefixed limit value, its frequency carrier is chosen by analysing the analytical model of the system, in order to reduce the voltage unbalance of the 3-level chopper input capacitors. The proposed control method is tested by simulation. Experimental tests have been started and the results will be presented to show the performance of the feed forward control method.