Abstract: Control circuitry uses modified average current mode control to regulate average current through an inductor of a power converter. Control circuitry uses modified average current mode control to regulate average current through an inductor of an active power filter. This average current mode control negates modulation of the average inductor current. In this way, output ripple current of the power converter does not have a significant effect on the input current drawn by the power converter.

Abstract: The invention is directed to the provision of a converter apparatus, an inverter apparatus, and a DC link voltage control method, wherein the upper limit value of the DC link voltage that rises due to regenerative energy occurring from a motor is set high, thereby increasing the regenerative energy to be stored in a DC link. The converter apparatus (10) comprises: a voltage detection part (11) for monitoring the DC link voltage occurring across the DC link (30); and a charge stopping part (12) for stopping charging a power storage part (C) when the detected value of the DC link voltage exceeds a predetermined upper limit voltage as the motor (3) is decelerated.

Abstract: A motor drive and a choke therefor are disclosed, wherein the choke comprises a magnetic core with an inner leg and two outer legs, and four coils, which may be connected in DC current paths in the motor drive. First and second differential coils are wound around first and second outer legs, respectively; and first and second common-mode coils are wound around the inner leg of the choke. The first and second differential coils smooth the DC current on a DC bus in the motor drive, and the first and second common-mode coils suppress common-mode voltages in the motor drive. Also disclosed is a method for suppressing common-mode voltages in a motor drive.

Abstract: A pulsating current inverter control circuit aims to convert AC power provided by an external electric source to a pulsating current through a rectification unit. The inverter has a control unit outputting an operation frequency to an actuation unit to divide the pulsating current to a plurality of electric pulse waves to drive a transformer to perform voltage transformation and drive a load. An inspection unit has a preset reference electricity value to compare with the pulsating current and output an activation signal and a deactivation signal to activate or deactivate the actuation unit. The transformer stops performing voltage transformation while the actuation unit is deactivated. Thus the transformer can output power to drive the load. The inspection unit can output a comparison signal to the control unit to alter the conductive interval of the operation frequency so that the inverter can output steady electricity in different AC environments.

Abstract: An inverter controlled generator set including: a power supply unit that uses a generator driven by an engine as a power supply to output a DC voltage; an inverter device that converts the output voltage of the power supply unit into an AC voltage; and a rotational speed control unit that controls a rotational speed of the engine so as to be kept at a target rotational speed suitable for a load applied to the inverter device, wherein the rotational speed control unit is comprised so that a settling time when the rotational speed of the engine is caused to converge to the target rotational speed in a state where the load is above a set value is longer than a settling time when the rotational speed is caused to converge to the target rotational speed in a state where the load is below the set value, in order to minimize an operation sound of the engine when the load is intermittently driven.

Abstract: A pulsating current inverter control circuit aims to convert AC power provided by an external electric source to a pulsating current through a rectification unit. The inverter has a control unit which outputs an operation frequency to an actuation unit to divide the pulsating current to a plurality of electric pulse waves to drive a transformer to perform voltage transformation and drive a load. The invention further includes an inspection unit which has a preset reference electricity value to compare with the pulsating current and output an activation signal and a deactivation signal to activate or deactivate the actuation unit so that the transformer stops performing voltage transformation while the actuation unit is deactivated. Thus the transformer can output power to drive the load as desired.

Abstract: Apparatus are disclosed for controlling the delivery of power to DC components such as computer components, microprocessors or the like. Designs of rectifier circuitry are presented which are appropriate for faster components, lower voltages, and higher currents. Embodiments are especially suited to applications which cause rapid changes in the conductance of the load, even in the sub-microsecond time domain as is common in computer applications and the like and in powering electronics equipment, especially a distributed system and especially a system wherein low voltage at high current is required. Embodiments and sub elements provide energy storage for low voltage, high current electronic loads, an ability to supply current with rapid time variation, providing extremely low inductance connections, permitting components to be located relatively remotely from the powered electronic load.

Abstract: A method of controlling of an induction machine using an inverter is disclosed with output LC filter. The method includes determining an inverter output current vector (iA), determining an inverter output voltage vector (uA), and forming a full-order observer having a system matrix (Â) and gain vector (K). The observer produces an estimated rotor flux linkage vector ({circumflex over (?)}R), an estimated stator current vector (îs), an estimated stator voltage vector (ûs) and an estimated inverter output current vector (îA). An estimation error (iA?îA) of the inverter output current vector is determined, and a speed adaptation law is formed based on the estimation error of the inverter output current vector for determining an estimate for electrical angular speed ({circumflex over (?)}m) of the induction machine. The induction machine is controlled based on the produced estimates and a measured inverter output current.

Abstract: The invention provides an apparatus for bi-directional power conversion between a DC circuit and an AC circuit, which inexpensively and simply suppresses generation losses of elements and reduces heat generation, wherein a voltage obtained by dividing the U-phase voltage Vu is compared with a voltage obtained by dividing the voltage vpn of a DC circuit by a comparator CP1, and the MOSFET UFETh is turned on at the output timing thereof, and a voltage obtained by dividing the V-phase voltage Vv is compared with a voltage obtained by dividing the voltage Vpn of a DC circuit by a comparator CP2, and the MOSFET UFETh is turned off at the output timing thereof.

Abstract: An input-side rectifier (4), a smoothing capacitor (6), an inverter (8), a transformer (10) and an output-side rectifier (12) operate together to convert an AC voltage supplied from an AC power supply to a DC voltage. The DC voltage is coupled through a DC-to-AC converter (16) to a workpiece (18) and a torch (20). An auxiliary voltage supply (28) supplies the workpiece (18) and the torch (20) with a negative voltage for a short time following the transition of the AC voltage supplied to the workpiece (18) and the torch (20) from positive to negative. The negative voltage has a negative peak value larger than the negative peak value of the AC voltage supplied to the workpiece (18) and the torch (20), and rapidly changes from the negative peak value.

Abstract: An uninterruptible power supply apparatus includes a first bidirectional power converter circuit having first and second ports and a second bidirectional power converter circuit having first and second ports. The apparatus further includes a DC link that couples the second port of the first bidirectional power converter circuit to the first port of the second bidirectional power converter circuit. A first load port is coupled to the second port of the second bidirectional power converter circuit and a second load port is coupled to the first port of the first bidirectional power converter circuit. The apparatus further includes a control circuit that is configured to control the first and second bidirectional power converter circuits such that each of the first and second bidirectional power converter circuits can generate and/or condition AC power at each of the first and second load ports.

Abstract: Method of controlling a voltage controlled PWM (Pulse Width Modulated) frequency converter comprising a single phase rectifier bridge (10) connectable to a sinusoidal single phase supply, a DC intermediate circuit (11) and a controlled inverter bridge (12) for generating an AC output voltage with varying amplitude and frequency to a load, said inverter bridge (12) having PWM controlled semiconductor switches (V11–V16) and flywheel diodes (D11–D16) connected in inverse-parallel with the semiconductor switches, wherein the DC intermediate circuit (11) is provided with a DC capacitor unit, and wherein the frequency converter is controlled so that the supply line current (Iin) is essentially sinusoidal and in phase with the supply line voltage (Uin).

Abstract: The invention relates to a cooling arrangement in a frequency converter, the arrangement being configured to convey heat generated at the frequency converter to a space surrounding the frequency converter, comprising a power part (10) of the frequency converter, a control part (20) and cooling means, comprising a cooling motor (31) and a transfer means (32) for producing cooling. In accordance with the invention, a cooling frequency converter is arranged in connection with the frequency converter to control the cooling means. The power part of the cooling frequency converter comprises a rectifier (11) of the frequency converter, an intermediate circuit (12) of the frequency converter as well as a unique power unit (43) of the cooling frequency converter.

Abstract: A power control interface between an unstable power source such as a wind farm and a power transmission line employs an electrical energy storage, control system, and electronic compensation module which act together like an “electronic shock absorber” for storing excess power during periods of increased power generation and releasing stored energy during periods of decreased power generation due to wind fluctuations. The control system is provided with a “look ahead” capability for predicting power output (wind speed conditions) and maintaining energy storage or release over a “narrow-band” range despite short duration fluctuations. The control system uses data derived from monitoring the wind farm power output and the power transmission line, and employs system-modeling algorithms to predict narrow-band wind speed conditions.

Abstract: A switching type power converter circuit includes a step-down converter circuit, a DC/AC converter circuit coupled to the step-down converter circuit, and a rectifier circuit coupled to the DC/AC converter circuit. In one embodiment, the DC/AC converter operates with near 50% duty cycle and with substantially zero-voltage, substantially minimum current switching in a resonant mode. An auxiliary step down converter may be added. An AC/DC converter front end with a full-wave bridge, an RF filter, and a power factor correction circuit may also be added.

Abstract: A dual bridge matrix converter has a line-side converter with controllable switches that receives AC power and provides unidirectional power to high and low DC link lines, and a load-side converter which receives the power from the DC link lines and provides AC power to output lines. A clamp circuit is connected across the DC link lines and includes a series connected diode and a capacitor. Negative DC link current will be conducted through the clamp diode to charge the clamp capacitor to avoid voltage spikes on the DC link lines. A controllable switch may be connected in parallel with the clamp diode and is turned on when the voltage across the clamp capacitor is above a threshold that is greater than the normal peak-to-peak AC input voltage. The switch is turned off when the voltage across the clamp capacitor is lower than the threshold voltage.

Abstract: A power conversion system which uses a plurality of transistors to convert DC power to AC power is made more efficient by the use of liquid refrigerant to cool the transistors. A plurality of passages are formed in a cold plate on which the transistors are mounted, and liquid refrigerant is flashed into the passages to cool the cold plate and the transistors. The liquid refrigerant can by derived from a condenser from an organic rankine cycle or a vapor compression cycle.

Abstract: A power flow controller for controlling the flow of active and reactive power on an AC transmission line between an input and output includes first and second power converters, coupled to each other to exchange active power and coupled to the input and output. A controller is coupled to the power converters and controls the converters to provide a controlled quantity of active power to the output, and draw this controlled quantity of active power from the input of the power flow converter. Electric current is diverted at a node between the input and the output, allowing independent control of currents at the input and output. In a preferred embodiment, the two power converters are interconnected in series. A controllable susceptance is connected in shunt at a node between the converters to divert the current.

Abstract: Method and apparatus are disclosed for providing a constant voltage, high frequency sinusoidal output across a varying load, using either a single or multiple switch topology operating at constant frequency while maintaining high efficiency over the entire load range. This embodiment is especially suited to applications which require the sinusoidal voltage be held very close to a desired value in the presence of rapid changes in the conductance of the load, even in the sub-microsecond time domain as is common in computer applications and the like and in powering electronics equipment, especially a distributed system and especially a system wherein low voltage at high current is required.

Abstract: A motor driving controller that drivingly controls motors for individual axes of an object of control comprises an AC/DC converter circuit for converting AC power into DC power and motor driving DC/AC converter circuits for converting DC power into AC power of optional frequency, for each motor. The controller further comprises an interface through which DC power from the AC/DC converter circuit is delivered to the outside. If motors for peripheral axes are added, motor driving DC/AC conversion devices are added and connected to the interface, whereby DC power is supplied.

Abstract: A power supply apparatus, such as an uninterruptible power supply, includes an AC input configured to be coupled to an AC power source and an AC output. The apparatus also includes an AC/DC converter circuit, e.g., a boost rectifier circuit, with an input coupled to the AC input. The apparatus further includes a DC/AC converter circuit, e.g., an inverter circuit, configured to be coupled between an output of the AC/DC converter circuit and the AC output. A bypass circuit is operative to establish a coupling between the AC input to the AC output in a first (e.g., bypassed) state and to interrupt the coupling in a second (e.g., “on line”) state. The AC/DC converter circuit is operative to control current at the AC input when the bypass circuit is in the first state. For example, the AC/DC converter circuit may be operative to control current at the AC input to correct a power factor at the AC input port when bypassed, such that the AC/DC converter circuit may act as a line conditioner in the bypassed state.

Abstract: A system and method of creating a pulse train signal of a pulse width modulator whose fundamental frequency is time-varying is disclosed. The electrical system includes a pulse width modulator which provides a pulse train signal. The system also includes a power source connected to the pulse width generator. The system further includes a binary counter having an input and a plurality of outputs, wherein the pulse train signal generated by the pulse width modulator is operatively coupled to the input of the binary counter. A plurality of resistors are operatively coupled to the plurality of outputs of the binary counter and operatively coupled to a node. A timing resistor is operatively coupled between a first voltage potential and the node, while a timing capacitor is operatively coupled between the node and a second voltage potential. The node is operatively coupled to an input of the pulse width modulator.

Abstract: A power control interface between an unstable power source such as a wind farm and a power transmission line employs an electrical energy storage, control system, and electronic compensation module which act together like an “electronic shock absorber” for storing excess power during periods of increased power generation and releasing stored energy during periods of decreased power generation due to wind fluctuations. The control system is provided with a “look ahead” capability for predicting power output (wind speed conditions) and maintaining energy storage or release over a “narrow-band” range despite short duration fluctuations. The control system uses data derived from monitoring the wind farm power output and the power transmission line, and employs system-modeling algorithms to predict narrow-band wind speed conditions.

Abstract: The present invention a method and apparatus for providing a visual messaging device for use with a high-speed network and an electrical supply system for the visual messaging device. The visual messaging device includes a network interface circuit that receives the message data from a network and arranges it in memory unit in usable form (packets) for use by a processor at the high network speed. The electrical supply system utilized with the visual messaging device comprises, in part, a power source, located in a remote location relative to a low voltage, high current device, which provides for the transmission of electrical power to the low voltage, high current device, such as a visual display unit, via relatively thin wiring or cabling passing through an enclosure, such as a plenum air space, without the need of placing the wiring or cabling in a conduit.

Abstract: A power conversion system which uses a plurality of transistors to convert DC power to AC power is made more efficient by the use of liquid refrigerant to cool the transistors. A plurality of passages are formed in a cold plate on which the transistors are mounted, and liquid refrigerant is flashed into the passages to cool the cold plate and the transistors. The liquid refrigerant can by derived from a condenser from an organic rankine cycle or a vapor compression cycle.

Abstract: A method of controlling an inverter power generation apparatus adapted to stop an operation of an inverter by stopping supplying a drive signal to a switch circuit of the inverter when an overload continuation time exceeds a first setting time in the state where a load current detected by a load current detector is equal to or more than a first overload judgment value and equal to or less than a second overload judgment value, to stop the operation of the inverter when the overload continuation time exceeds a second overload judgment value set in accordance with an output voltage of the inverter in the state where the load current exceeds the second overload judgment value and the output voltage of the inverter is higher than a short circuit judgment value and to stop the operation of the inverter immediately when the load current exceeds the second overload judgment value and the output voltage of the inverter is equal to or less than the short circuit judgment value whereby the inverter can be positively pr

Abstract: A switching type power converter circuit includes a step-down converter circuit, a DC/AC converter circuit coupled to the step-down converter circuit, and a rectifier circuit coupled to the DC/AC converter circuit. In one embodiment, the DC/AC converter operates with near 50% duty cycle and with substantially zero-voltage, substantially minimum current switching in a resonant mode. An auxiliary step down converter may be added. An AC/DC converter front end with a full-wave bridge, an RF filter, and a power factor correction circuit may also be added.

Abstract: A fine vacuum tube element and other electronic elements are integrated and formed on a semiconductor substrate, and the fine vacuum tube element and the other electronic elements transmit signals to and from each other. When integrating the vacuum tube element with the other electronic elements, a quantum effect is realized in a room temperature environment by utilizing ballistic electrons (non-scattering electrons) traveling through the vacuum, and in the integrated circuit, an A/D converter is constructed by an interference system such as a Mach-Zehnder interferometer. Also an integrated circuit of an advanced function-integrated type is provided, comprising an interference system such as a Mach-Zehnder interferometer wherein weighting of the Mach-Zehnder interferometer is constituted for image processing and signal code conversion.

Abstract: A power controller includes power storage means for storing DC power from DC power generation means that. Power conversion means include a DC/DC converter that converts a voltage when receiving a DC input. Charge and discharge means discharge electric power from the power storage means to the power conversion means and charge DC power from the DC power generation means in the power storage means. The charge and discharge means are provided among the DC power generation means, the power storage means and the power conversion means. Detection means detect electric energy of an external power load to which power from at least the power conversion means is supplied. Control means control operation of the charge and discharge means on the basis of the detected electric energy.

Abstract: Method and apparatus are disclosed for providing a constant voltage, high frequency sinusoidal output across a varying load, using either a single or multiple switch topology operating at constant frequency while maintaining high efficiency over the entire load range. This embodiment is especially suited to applications which require the sinusoidal voltage be held very close to a desired value in the presence of rapid changes in the conductance of the load, even in the sub-microsecond time domain as is common in computer applications and the like and in powering electronics equipment, especially a distributed system and especially a system wherein low voltage at high current is required.

Abstract: A power generation apparatus includes a permanent-magnet AC generator, a first converter for converting AC power into DC power, and a second converter for converting the DC power produced by the first converter into AC power. The first converter includes a unit for controlling active power and a unit for controlling reactive power and the second converter includes a unit for controlling a voltage of a DC system and reactive power or AC voltage of a power system.

Abstract: This invention relates to a power supply that integrates a rectifier/filter's circuitry and a converter's circuitry with an inverter to reduce space occupied and increase power efficiency. The power supply includes: a rectifier/filter, a DC-DC converter and a DC-AC inverter. The rectifier/filter, connected to an alternating current (AC) input terminal, converts the input AC into a direct current (DC). The DC-DC converter and the DC-AC inverter are parallel to each other with one end concurrently connected to the rectifier/filter's output and the other end respectively outputting the desired powers. As such, DC-DC converter reduces the converted DC voltage to lower DC voltages to power all circuits except for the lamp and DC-AC inverter converts the converted DC voltage into higher AC voltage output to drive the lamp.

Abstract: The DC/DC converter provides an output current which is periodically variable over time and includes a control network which generates a variable reference signal for the input current which is substantially smoothed and obtained from the difference between the output voltage and a reference voltage.

Abstract: A low side switching driver circuit (50) includes an emitter follower circuit, an input buffer (51), and a power source (52) and capacitors (53, 54) for driving these circuits. The power source (52) is not provided for each one of low side switching elements (5, 6, 7), but the low side switching elements (5, 6, 7) use the power source (52) as a common power source thereamong. A resistor (58) is provided between the node between the negative pole of the capacitor (53) and a first low potential power source line, and a second low potential power source line (G) of the low side switching driver circuit. The capacitor (54) is connected to the input buffer (51). Resistors (59, 60) as current limiting elements are provided between the input buffer (51) and the power source (52).

Abstract: In a solar power generation system having an inverter, if a smoothing capacitor in the inverter degrades, the operation of the inverter is interrupted, and a loss in the amount of power generation occurs inevitably. To prevent this loss, a degradation determination section (211) and output suppressing section (212) are provided in an inverter (2). If the degradation determination section (211) determines a degradation in capacitor (24), the operation of the inverter (2) is continued while suppressing the output current of the inverter (2) by the output suppressing section (212). In addition, a warning section (213) warns the user about the degradation in capacitor (24). With this arrangement, a solar power generation system capable of detecting a degradation in smoothing capacitor in the inverter (2) and appropriately operating the inverter (2) can be provided.

Abstract: A motor driving controller that drivingly controls motors for individual axes of an object of control comprises an AC/DC converter circuit for converting AC power into DC power and motor driving DC/AC converter circuits for converting DC power into AC power of optional frequency, for each motor. The controller further comprises an interface through which DC power from the AC/DC converter circuit is delivered to the outside. If motors for peripheral axes are added, motor driving DC/AC conversion devices are added and connected to the interface, whereby DC power is supplied.

Abstract: When islanding operation is to be detected in a power conversion apparatus for converting a DC power into an AC power and outputting the AC power to a system power supply, a plurality of variation generation means for executing, in accordance with different schemes, detection of islanding operation in which power supply from the system power supply is stopped are arranged, and at least one variation generation means is selected by selection means from the plurality of variation generation means and operated.

Abstract: The amplifier comprises instantaneously interruptible power source (I2PS) for producing a precise AC output voltage. A continuous mode I2PS can be built using only 7 power components, including two inductors and an output capacitor. The I2PS can instantaneously interrupt the correction and become idle. The inductors each attain a corrective current and provide a return voltage. Two switches are separately coupled in series with the inductors for selectively applying the respective corrective currents between the power supply and the output capacitor. Two diodes limit the return voltages. A converter converts the supply voltage or an internal voltage into an internal supply current. A fine amplifier can employ two low power transistors to rapidly deliver a fine current to the output capacitor. This dramatically reduces output noise and improves accuracy. The converter and the fine amplifier can be combined or used separately. The I2PS having unity gain is most accurate and requires a simple preamplifier.

Abstract: The present invention is directed to an active converter system for a permanent magnetic turbogenerator. A system in accordance with an embodiment of the present invention includes a DC voltage link and a first active converter including a connection for inputting or outputting a three-phase AC voltage to or from, respectively, an AC voltage source, another connection for inputting or outputting a DC voltage from or to said DC voltage link, and at least six selectively switchable first IGBTs, wherein selective switching of the first IGBTs results in a boosted DC voltage. The system further includes a second active converter including a connection for inputting or outputting a three-phase AC voltage to or from, respectively, a permanent magnetic generator, another connection for inputting or outputting a DC voltage to or from said DC voltage link, and at least six selectively switchable second IGBTs, wherein the second active converter is capable of boosting said DC voltage.

Abstract: A power generation apparatus includes a permanent-magnet AC generator, a first converter for converting AC power into DC power, and a second converter for converting the DC power produced by the first converter into AC power. The first converter includes a unit for controlling active power and a unit for controlling reactive power and the second converter includes a unit for controlling a voltage of a DC system and reactive power or AC voltage of a power system.

Abstract: A cooking device having a cooking chamber, a motor unit for driving a fan for purposes of circulating cooking chamber atmospheres in the cooking chamber, a control and regulator unit cooperating with the motor unit and a voltage phase and frequency converter which has power supply connections for the input of a.c. voltage signals L1 and at least one connection to the control and regulator unit and an output connection for transmitting three-phase voltage signals U, V and W with adjustable amplitude, frequency and phase to the motor unit.

Abstract: A charging circuit includes a fast transient input path to improve the transient response of the charging circuit and to avoid related problems such as inadvertent tripping of a power source. A charging circuit system and laptop computer including a charging circuit consistent with the invention is also provided. A method of allocating power from a power source configured to charge a battery includes sensing at least one predetermined supply parameter from a power source, providing a first control signal after a first time interval based on the sensing, providing a second control signal after a second time interval based on the sensing, wherein the second time interval is less than the first time interval, and regulating power to the battery based on at least one of the first and second control signals.

Abstract: Circuits and methods for protecting thyristors in a bridge configuration are provided. A circuit comprises a line reactor in series with the input of the bridge and the input of the diametric cell, two leg reactors each in series with a respective leg and an output of the diametric cell. Two snubber circuits in parallel with the two thyristors that comprise the diametric cell may also be used to protect the thyristors.

Abstract: Method and apparatus are disclosed for providing a constant voltage, high frequency sinusoidal output across a varying load, using either a single or multiple switch topology operating at constant frequency while maintaining high efficiency over the entire load range. This embodiment is especially suited to applications which require the sinusoidal voltage be held very close to a desired value in the presence of rapid changes in the conductance of the load, even in the sub-microsecond time domain as is common in computer applications and the like and in powering electronics equipment, especially a distributed system and especially a system wherein low voltage at high current is required.

Abstract: A discharge lamp driving device capable of detecting a lamp life end reliably in a high or low temperature environment for circuit protection, yet preventing the occurrence of the cataphoresis phenomenon. Impedance elements Z1 and Z1 are inserted respectively between one filament ends of individual discharge lamps La1 and La2 and a node (the ground) having no high frequency amplitude in order to detect a difference between AC components of individual lamp voltages VLa1 and VLa2 in closed loops of the discharge lamps La1 and La2 and the impedance elements Z1 and Z1 in order to judge whether or not the depletion of the emitter occurs. Thus, it is possible to reliably judge the presence of abnormality even when the amplitudes of the lamp voltages VLa1 and VLa2 varies in a range of low to high temperature.

Abstract: The present invention provides a simple circuit for a DC power supply. The power supply circuit of the present invention includes a transformer in combination with a switching power supply circuit. The transformer includes a primary winding to which a wide range of AC input voltages is applied and a secondary winding for supplying the resultant AC voltage range as an input voltage to the switching power supply circuit. The switching power supply circuit further includes an input terminal having the input voltage applied thereto by the secondary winding and further having an output terminal from which a DC power supply output is generated. The transformer can be selected from a group of transformers consisting of step-down, step-up and repeater transformers. The switching power supply circuit may be selected from any convention switching power supply circuit including step-up, step, down and inverter converters, and combinations thereof, or even linear configurations.

Abstract: A method of controlling a parallel operation of two inverter power generation apparatuses wherein an unbalance of outputs from the two inverter power generation apparatuses is cancelled by judging that the outputs of the two inverter power generation apparatuses have the collapse of the balance between them when a DC power supply voltage obtained from a DC power supply section exceeds a judgment value set at a value equal to or more than a non-load output voltage of the DC power supply section and allowing an overload operation of the inverter power generation apparatus of higher output voltage among the two inverter power generation apparatuses so as to lower the output voltage of the corresponding inverter power generation apparatus.

Abstract: The present invention provides a visual messaging device for use with a high-speed network and an electrical supply system for the visual messaging device. The visual messaging device includes a network interface circuit that receives the message data from a network and arranges it in memory unit in usable form (packets) for use by a processor at the high network speed. The electrical supply system utilized with the visual messaging device comprises, in part, a power source, located in a remote location relative to a low voltage, high current device, which provides for the transmission of electrical power to the low voltage, high current device, such as a visual display unit, via relatively thin wiring or cabling passing through an enclosure, such as a plenum air space, without the need of placing the wiring or cabling in a conduit.

Abstract: To minimize the energy required for operation of a rail vehicle, in a drive system that has an intermediate circuit converter 1 and a three-phase motor 7 fed by it, the intermediate circuit voltage in the intermediate circuit 12 and/or the magnetic flux in the drive motor 7 are optimized to correspond to the actual operating requirements, including, if necessary, the energy expenditure for the auxiliaries 9 that are provided to cool the components.

Abstract: The present invention provides a control algorithm which instantaneously detects magnetic pole positions in the inside of a motor including polarities of the motor. A controller 1 applies a minute voltage change vhd to a voltage command on a dc axis which constitutes an estimation magnetic pole axis of the motor 3, detects electric currents Idc, Iqc of a motor 3 and discriminates the polarities of the magnetic pole axes by making use of the difference between a cycle in which ripple components of the electric currents Idc, Iqc become positive and a cycle in which the ripple components become negative or the difference between positive-side and negative-side current change rates. Further, the minute voltage change vhd with respect to the above-mentioned voltage command is generated on both of the dc axis and the qc axis rectangular thereto, and the magnetic pole positions of the motor are directly estimated based on the current ripple components on the respective axes.