Abstract: A nitride semiconductor structure including a silicon substrate, a nucleation layer, a buffer layer and a nitride semiconductor layer is provided. The nucleation layer is disposed on the silicon substrate. The buffer layer is disposed on the nucleation layer, in which the buffer layer includes n sub-buffer layers where n?2, and each of the sub-buffer layers has island structures. The nitride semiconductor layer is disposed on the buffer layer.

Abstract: A power conversion apparatus includes a high-power-factor converter section converting an AC voltage to a DC voltage, a smoothing capacitor, a DC/DC converter section, and a control circuit. The control circuit controls the high-power-factor converter section such that the power factor of AC is controlled and a DC voltage follows a target value, and performs duty control for semiconductor switching devices such that a DC voltage from the DC/DC converter section to a load follows an instruction value. In accordance with the DC voltage, the control circuit adjusts the DC voltage target value of the high-power-factor converter section such that the duty ratio of the semiconductor switching devices approaches a set value, thereby optimizing the duty ratio of the semiconductor switching devices and reducing power loss.

Abstract: A controller for a three-phase AC motor includes a current sensor and a current estimation section. The current sensor detects current flowing through one phase of the motor. The one phase is defined as a sensor phase. The current estimation section calculates a current phase relative to an axis of the sensor phase based on ?-axis current and ?-axis current in a stationary coordinate system defined by a ?-axis parallel to the sensor phase axis and a ?-phase perpendicular to the sensor phase axis. The current estimation section estimates current flowing through another phase of the motor based on the current phase and the detected current. The current estimation section calculates the ?-axis current based on the detected current. The current estimation section calculates the ?-axis current based on the detected current and a command value for the current flowing through the other phase of the motor.

Abstract: A control device for an induction motor that drives a vehicle includes an electronic control unit. The electronic control unit i) controls torque of the induction motor when an inverter that controls supply of electric current to the induction motor is in a locked state, so as to release the inverter from the locked state, ii) determines whether the inverter is in the locked state, iii) controls a slip frequency of the induction motor when it determines that the inverter is in the locked state, and iv) superimposes a frequency that actual torque does not substantially respond, on the slip frequency, so that an electric frequency lies in a region outside a lock region in which the inverter is in the locked state.

Abstract: A power supply system for data center racks comprises a main power circuit including a power factor correction (PFC) module and a bypass power circuit in parallel to the main power circuit. During normal operation, the main power circuit provides power output because the output voltage of the PFC module in the main power circuit under normal conditions is higher than the output voltage of the bypass power circuit. When the PFC module in the main power circuit fails, the bypass power circuit provides power output in bypass operation. The bypass power circuit provides power by rectifying a three-phase AC current to produce an output suitable for equipment that uses DC power.

Abstract: A high voltage, high power multi-level drive structure includes a plurality of neutral-point-piloted (NPP) converter cells stacked together. At least one clamping diode is connected to one or many NPP converter cells to provide a neutral-point-pilot-clamped (NPPC) converter structure. Flying capacitors connected to the NPPC converter structure yield a neutral-point-clamped-flying-capacitor converter cell structure.

Abstract: Provided is an over-current protection apparatus including a current sensor configured to transform input current into a voltage signal, and output the voltage signal; an over-current sensing unit driven according to the voltage signal output from the current sensor; and an over-current determination unit configured to generate a switching unit driving signal, the logic level of which is determined according to a duration of an output signal of the over-current sensing unit.

Abstract: A synthetic space vector modulation method and device for controlling a voltage source inverter and load is provided. The device and method comprise a variable frequency oscillator (VFO), a center-aligned pulse-train signal generator, a modulo-N counter, and a three-phase time division multiplexer. The VFO outputs a square wave to the modulo-N counter and a triangle wave of the same frequency to the center-aligned pulse-train signal generator, the outputs of the center-aligned pulse-train generator and the modulo-N counter are sent to the three-phase time division multiplexers, and after leaving the multiplexers, and before being sent to the VSI controller's load each positive and each negative output of the multiplexing phase is sent to a turn-on delay. The present innovation makes VSI controller acquisition and repair almost as simple as buying and repairing a transistor radio.

Abstract: An on-load tap changer is provided having a plurality of modules, each of which is operable to change taps in a winding of a transformer. A transmission shaft is connected to the modules and is operable upon rotation to effectuate tap changes in the windings. A servo motor rotates the transmission shaft. The servo motor includes a feedback device operable to generate a feedback signal containing information relating to the position of the motor shaft. A servo drive is connected to the servo motor to receive the feedback signal. The servo drive uses the feedback signal to determine and store a total angular displacement of the motor shaft. The servo drive uses the feedback signal and the total angular displacement of the motor shaft to control the operation of the servo motor.

Abstract: Microinverters useable in association with photovoltaic modules are described. A three phase-microinverter receives direct current output generated by a microsystems-enabled photovoltaic cell and converts such direct current output into three-phase alternating current out. The three-phase microinverter is interleaved with other three-phase-microinverters, wherein such microinverters are integrated in a photovoltaic module with the microsystems-enabled photovoltaic cell.

Abstract: A power converting apparatus according to an embodiment includes a controller that controls a power converter. The controller includes a first signal generator which generates switch drive signals for AC-to-DC conversion, a second signal generator which generates switch drive signals for DC-to-AC conversion, and a drive signal generator which generates, in accordance with the switch drive signals for AC-to-DC conversion and the switch drive signals for DC-to-AC conversion, switch drive signals for controlling the power converter. The first signal generator and the second signal generator operate in synchronization with each other.

Abstract: Methods and systems for transforming electric power between two or more portals. Any or all portals can be DC, single phase AC, or multi-phase AC. Conversion is accomplished by a plurality of bi-directional conducting and blocking semiconductor switches which alternately connect an inductor and parallel capacitor between said portals, such that energy is transferred into the inductor from one or more input portals and/or phases, then the energy is transferred out of the inductor to one or more output portals and/or phases, with said parallel capacitor facilitating “soft” turn-off, and with any excess inductor energy being returned back to the input. Soft turn-on and reverse recovery is also facilitated. Said bi-directional switches allow for two power transfers per inductor/capacitor cycle, thereby maximizing inductor/capacitor utilization as well as providing for optimum converter operation with high input/output voltage ratios. Control means coordinate the switches to accomplish the desired power transfers.

Abstract: A power semiconductor module in which temperature rise of switching elements made of a Si semiconductor can be suppressed low and efficiency of cooling the module can be enhanced. To that end, the power semiconductor module includes switching elements made of the Si semiconductor and diodes made of a wide-bandgap semiconductor, the diodes are arranged in the middle region of the power semiconductor module, and the switching elements are arranged in both sides or in the periphery of the middle region of the power semiconductor module.

Abstract: Methods and systems for power conversion. An energy storage capacitor is contained within an H-bridge subcircuit which allows the capacitor to be connected to the link inductor of a Universal Power Converter with reversible polarity. This provides a “pseudo-phase” drive capability which expands the capabilities of the converter to compensate for zero-crossings in a single-phase power supply.

Abstract: There are provided an electric charging system and an electric vehicle. The electric vehicle has a battery and is provided with power receiving terminals for charging. A converter is provided between the battery and the power receiving terminals, and relays are provided between the converter and the power receiving terminals. An electric charger is provided with a power converter that outputs charging power and power supply terminals connected to the power converter. When the interruption of charging power supply from the power converter fails during charging, the converter is actuated and the stored electric power of the battery is boosted and supplied to the relays.

Abstract: An inverter control section controls the inverter by controlling an armature current in a two-axis orthogonal coordinate system that rotates in synchronization with the rotary electric machine, the armature current being a vector obtained by synthesizing a field current and a drive current extending along respective axes of the orthogonal coordinate system. If it is determined that connection between the DC power source section and the inverter is in a blocked state, the inverter control section executes zero-torque control in which the inverter is controlled such that torque regenerated by the rotary electric machine becomes zero, and executes high-loss control in which the field current is varied so as to increase the armature current while maintaining a torque command provided in the zero-torque control.

Abstract: A power supply device includes a converter, a rectifier circuit, a voltage cycle detection circuit, and a power supply cutoff signal output unit. The converter converts an AC voltage inputted from an external power supply to a DC voltage and outputs the DC voltage. The rectifier circuit rectifies the AC voltage inputted from the external power supply and outputs a rectified waveform voltage. The voltage cycle detection circuit detects a voltage cycle in which the rectified waveform voltage reaches a predetermined threshold value and, when the voltage cycle is detected to be longer than a predetermined cycle, outputs a voltage cycle abnormality signal. The power supply cutoff signal output unit outputs a power supply cutoff signal when the voltage cycle abnormality signal is inputted.

Abstract: A multiple dc sources bi-directional energy converter includes a plurality of direct current (DC) power sources; one alternating current (AC) power source; at least one stacked alternating current (AC) phase, each stacked alternating current (AC) phase having at least two or more full bridge converters, each respectively coupled to one of the direct current power sources, each full bridge converter having an inductor electrically coupled thereto; and a local controller coupled to each full bridge converter controlling the firing sequence of the switching devices in said full bridge converter to generate an approximately nearly sinusoidal voltage waveform when operated as a voltage source inverter in one direction or generate an approximately nearly constant direct current (DC) output when operated as a full-wave active rectifier in the opposite direction.

Abstract: A motor current detecting device includes a first wire, an instantaneous current detecting unit, an average electric current detecting unit, and a calculation unit. The first wire is configured and arranged to carry flow of a motor current that has been passed through a motor and a drive current that has been passed through a motor drive unit to drive the motor. The instantaneous current detecting unit is configured and arranged to detect an instantaneous value for a sum of the motor current and the drive current flowing on the first wire. The average electric current detecting unit is configured and arranged to detect an average value of the sum of the motor current and the drive current flowing on the first wire. The calculation unit is configured to calculate the motor current on the basis of the instantaneous value and the average value.

Abstract: A shaft-driven generator system has a generator connected to a converter. An inverter supplies an AC voltage on a network side. The converter and the inverter are linked via a DC link circuit. The inverter has at least two phase modules, which each have an upper and a lower valve branch, which each have a plurality of two-pole sub-systems connected electrically in series. Each sub-system has a unipolar storage capacitor, to which a series circuit of two gate-controlled turn-off semiconductor switches is connected electrically in parallel. Each semiconductor switch has a diode connected antiparallel therewith. Thus, a shaft-driven generator system is obtained that has a DC-link converter as a static frequency converter for complying with the required network feedback and for managing transient operating states.

Abstract: A motor control circuit calculates, based on a sensed current of a sensor phase sensed by a current sensor, an estimated current of the other phase and calculates a d-axis and a q-axis estimated currents based on the sensed current of the sensor phase and the estimated current of the other phase. The motor control circuit further calculates a d-axis and a q-axis command voltages based on the estimated currents thereby to control power supply to the AC motor. When the sensed current of the sensor phase is 0 [A], the command voltages are fixed and the estimated current is interpolated. Thus, variations of the command voltages caused by an error in the estimated current are reduced and a rapid change in the estimated current is reduced.

Abstract: A control system includes first and second fundamental control units for generating first and second fundamental commands, and a compensation control unit. The compensation control unit includes first and second calculation elements and a comparator for comparing first and second modulation indexes. When the first modulation index is less than the second modulation index, the first calculation element generates a first source-side compensation command. When the first source-side compensation command is not sufficient to balance the neutral point voltage, the first calculation element further generates a first line-side compensating command. When the first modulation index is greater than the second modulation index, the second calculation element generates a second line-side compensation command. When the second line-side compensation command is not sufficient to balance the neutral point voltage, the second calculation element further generates a second source-side compensating command.

Abstract: An inverter for converting an input direct current (DC) waveform from a DC source to an output alternating current (AC) waveform for delivery to an AC grid includes an input converter, an output converter, an input controller, and an output controller. The input controller is configured to control the operation of the input converter, and the output controller is configured to control the operation of the output controller. The input and output controllers are electrically isolated from each other and may be incapable of direct communications between each other. In some embodiments, the input and output controllers may communicate with each other via the input and output converters.

Abstract: Capacitors are connected in series between a first DC link section and a second DC link section when the capacitors are charged by a regenerative current derived from an inverter section. During discharge, as first, second switching circuits turn on, the capacitors are discharged with those capacitors connected in parallel between a first DC link section and a second DC link section.

Abstract: A voltage balancing unit for a symmetric monopole high voltage direct current (HVDC) transmission line interconnecting two voltage source converters (VSCs), the transmission line including first arresters having a first switching impulse protective level (SIPL) is provided. The voltage balancing unit includes a pair of second arresters having a second SIPL which is less than the first SIPL, and a switching device being arranged for temporarily connecting, in the event of a voltage unbalance on the transmission line, the first arresters between either pole and ground. A voltage unbalance on the transmission line may be removed by temporarily connecting second arresters, with a significantly lower SIPL than the first arresters, for limiting the pole voltage to a level close to the normal voltage. Further, a method of voltage balancing is provided. Voltage unbalances may arise as a consequence of lightning induced earth faults.

Abstract: A load control circuit includes one or more current regulators, in particular in an electronic motor vehicle control unit, wherein one or more preferably inductive load(s) is/are connected to a circuit located outside the control unit or inside the control unit, and wherein the load current flowing through the load(s) is or can be reduced by way of one or more step-down converters to a voltage potential below the supply voltage. A step-down converter includes a clocked DC/DC converter having at least one clocked switch and an energy storage medium, in particular a capacitor, for conversion, wherein the clock control of the switch or switches is modified according to the charge state of the energy storage medium and wherein the charge state is determined according to the voltage present at the energy storage medium.

Abstract: Parallel converter current imbalance control apparatus and methods in which individual converter AC currents are measured for each phase, and the AC voltage control modulation indices associated with the converters having the highest and lowest AC currents for a given phase are adjusted to counteract current imbalance between the converters.

Abstract: Provided is a power conversion system that includes a first transformer adapted to be connected to an AC network, the first transformer including a first primary winding and two first secondary windings, and two power converters, each being connected to a first respective secondary winding. The system further includes a second transformer and a secondary electrical device, the second transformer including a second primary winding and two second secondary windings, each second secondary winding being connected to a respective first secondary winding, and the secondary device being connected to the second primary winding.

Abstract: Methods and systems for managing link voltages in a power converter, where single phase, three phase or universal systems can be used. Common mode management refers to shifting of voltages in a particular direction to perform transition between input and output ports, in addition to maintaining soft switching property. Voltages in power converters can be freely increasing and decreasing, and thus damage to the circuit can be caused if these voltages change are not controlled.

Abstract: A power conversion circuit includes: an AC-DC circuit, a direct current-alternating current DC-AC circuit, and a first filter capacitor. The DC-AC circuit includes: a third bridge arm, a fourth bridge arm, a first inductor, a second inductor, a first switch transistor, and a second switch transistor, a second end of the first inductor is connected to a first end of the first switch transistor, a second end of the first switch transistor is connected to the direct current bus, a first end of the second inductor is connected to a connection point of two switch transistors included by the fourth bridge arm, a second end of the second inductor is connected to a first end of the second switch transistor, and a second end of the second switch transistor is connected to the direct current bus.

Abstract: A pre-charging circuit of inverter is disclosed, the pre-charging circuit of inverter including a relay arranged between an output node of the rectifier and an input node of the DC-link capacitor, and a pre-charging resistor arranged between an output node of the rectifier and an input node of the inverter unit, whereby a degree of freedom for PCB design can be obtained.

Abstract: In a thyristor control device which converts a first AC voltage to a DC voltage and converts the DC voltage to a second AC voltage to be supplied to a synchronous motor, a DC voltage detector is configured to detect the DC voltage, and is provided with an AC voltage detector configured to detect the second AC voltage and an arithmetic circuit configured to determine the DC voltage on the basis of the second AC voltage detected by the AC voltage detector. As a result, there is no need to separately provide a DV voltage detector, which makes it possible to make the device compact in size and cheap in price.

Abstract: A power converter includes an active front end (AFE) that is coupled by a dc link stage to a plurality of H-bridge inverters. One or more multi-phase electro-magnetic energy conversion devices, such as transformers or electric machines, with open windings that are connected to only the AFE or only the H-bridge inverters or to both the AFE and H-bridge inverters, provide a regenerative or partial regenerative power converter.

Abstract: According to one embodiment, there is provided a power-fluctuation reducing apparatus in a power generation system to control a converter connected to the power generation system and connected to secondary batteries. The power-fluctuation reducing apparatus includes adjusting direct current voltages output from the secondary batteries, respectively, detecting the directing current voltages output from the secondary batteries, respectively, controlling to adjust the direct current voltages output from the secondary batteries to make the direct current voltages uniform, based on the detected direct current voltages, and controlling the converter to reduce power fluctuations in the power generation system.

Abstract: A system for controlling photovoltaic electricity production equipment having photovoltaic modules each equipped with a DC/DC microconverter connected to a DC bus, a DC bus manager, and an inverter for converting the direct current from the photovoltaic panels into alternative current intended for an electrical distribution network. Power is injected into the DC bus when the voltage of the DC bus is less than a minimum voltage until the minimum voltage is reached. Each of the microconverters injects a maximum power from the photovoltaic modules into the DC bus when the voltage of the DC bus is between a first voltage and a second voltage. The injecting of power from the photovoltaic modules into the DC bus is stopped when the voltage of the DC bus is less than a low threshold voltage or greater than a high threshold voltage.

Abstract: A system, method, and apparatus for providing three level inverter modulation is disclosed. In one embodiment, control signals can be provided to control a three level inverter in a power converter based on at least one feedback signal.

Abstract: In the ground fault detecting circuit, one terminals of first to third resistance elements are connected to first to third AC lines, respectively, the other terminals of the first to third resistance elements are commonly connected to one terminal of a fourth resistance element, and the other terminal of the fourth resistance element is connected to a line of a ground voltage. On the basis of a voltage across the terminals of the fourth resistance element, the ground fault detecting circuit detects whether a ground fault has occurred or not. Since a current does not flow through the fourth resistance element in the normal state and flows through the fourth resistance element after the occurrence of a ground fault, it is possible to detect the occurrence of the ground fault at a high accuracy.

Abstract: A power conversion device according to the aspects of the present technique is presented. The device includes a first converter and a second converter operatively coupled to the first converter. Moreover, the device includes a phase leg operatively coupled between the first converter, the second converter, where the phase leg includes a first unidirectional switch, a second unidirectional switch operatively coupled to the first unidirectional switch, and a first bidirectional switch, where a first end of the first bidirectional switch is operatively coupled to at least one of the first unidirectional switch and the second unidirectional switch.

Abstract: A method for controlling voltage of a DC bus in a converter circuit is provided. The method includes monitoring a duty cycle of a switch that connects a resistive circuit across the DC bus, the switch being closed when the DC bus voltage reaches an upper voltage value and opened when the DC bus voltage reaches a lower voltage value and altering the lower voltage value based upon the duty cycle of the switch.

Abstract: Power conversion equipment which can detect a short circuit failure of series connected smoothing capacitors is provided. The equipment includes a capacitor failure detecting circuit having switch units, exciting resistors, contact resistors, and diodes. A switch unit is provided with an exciting circuit and a contact circuit, and when a predetermined current flows through the exciting circuit, the contact circuit is closed. The exciting circuit and an exciting resistor are alternately connected in series, and the contact circuit and a contact resistor are alternately connected in series. These serially-connected circuits are connected in parallel with each capacitor. When excitation of a switch circuit having a lowest potential is turned OFF, it is judged that one or more of the series connected capacitors has failed via a short circuit.

Abstract: A method is disclosed for operating a converter circuit, in which controllable power semiconductor switches of the rectifier unit of a converter circuit are controlled by a rectifier switch signal and the controllable power semiconductor switches of the inverter unit of the converter circuit are controlled by an inverter switch signal. In order to reduce losses in the no-load state of the converter circuit, the rectifier switch signal is blocked in order to disconnect the controllable power semiconductor switches of the rectifier unit if defined conditions of the converter circuit are fulfilled.

Abstract: The present application relates to a cascaded H-Bridge medium voltage drive, a power cell, and a bypass module thereof, wherein the bypass module is configured for bypassing a major circuit module of the power cell, while the major circuit module comprises a fuse, a rectifier, a bus capacitor and an H-Bridge inverter, two points led from the H-Bridge inverter being configured as a first output end and a second output end; a bypass circuit comprises a first bridge arm and a second bridge arm; a point led from the first bridge arm is configured as a first input end of the bypass circuit, a point led from the second bridge arm is configured as a second input end of the bypass circuit, and the first input end is electrically connected with the first output end, the second input end is electrically connected with the second output end.

Abstract: A high efficiency, multi-mode, regenerative AC-DC-AC inverter power system contains an inverter bridge, a bi-phase matrix (BP-Mtx) containing reverse current oriented, series-connected sets of controllable switches, wherein inputs to a first and second set of controllable switches are coupled to the inputs of the first inverter bridge, and outputs of the first and second set of controllable switches are coupled to inputs to a third set of controllable switches. A chargeable DC power supply is coupled to an output of the third set of controllable switches. The load-side DC-bus is coupled to outputs of the first inverter bridge and a second inverter bridge. The switches of the first inverter bridge, second inverter bridge, and BP-Mtx are modulated to charge the DC power supply from either excess voltage from line inputs or the DC-bus, and to provide compensating energy from the DC power supply for load or line input perturbations.

Abstract: The present invention provides a high-power medium-voltage drive power cell, which comprises: a rectifier module for rectifying the three-phase AC input voltage to get a DC voltage; an IGBT (Insulated Gate Bipolar Transistor) inverter bridge connected to capacitors for converting the DC voltage into an AC voltage of which the frequency, the amplitude and the phase are adjustable; a bypass module connected to the IGBT inverter bridge for providing the bypass function when the IGBT inverter bridge works in an abnormal state; and a heat pipe heat sink having a base plate on both sides of which power elements of the high-power medium-voltage drive power cell are disposed.

Abstract: A DC-to-AC power converter is disclosed. The power converter has a DC input to receive DC power from a photovoltaic device, an AC output configured for direct connection to an AC mains power supply line, six semiconductor switches, one isolated high-frequency power transformer, two high-frequency inductors, a small resonant capacitor, and a large non-electrolytic (e.g. film) capacitor energy storage component. One of the semiconductor switches located on the primary side of the transformer operates to regulate the voltage across the non-electrolytic capacitor energy storage component. A second semiconductor switch located on the primary side of the transformer provides a resonant reset for the energy stored in the transformer and allows the first semiconductor switch to operate with nearly zero-voltage-switching.

Abstract: A power converting apparatus for electric motor vehicle propulsion is provided that is suitable for a use in which power regeneration from an inverter unit to a power storing unit or power supply from the power storing unit to the inverter unit is frequently used. The apparatus includes a converter unit that receives input of a power supply voltage from the outside, converts the power supply voltage into a direct current of a predetermined value, and outputs the direct current, the inverter unit that is connected to an output side of the converter unit and drives an electric motor, and the power storing unit that is connected to the output side of the converter unit. A converter control unit included in the converter unit generates a current command for the converter unit and controls charging and discharge currents to and from the power storing unit based on this current command.

Abstract: Bypassing methods and apparatus are presented along with power cells and sub cells for multilevel inverters in which DC current flow into a DC link capacitance is interrupted and a bypass switch is closed across a power cell or sub cell output to selectively bypass a power stage of a multilevel inverter.

Abstract: The present invention provides an excitation control circuit and the electrically excited wind power system having the same. The excitation control circuit includes a plurality of full-power converters, each of which has a generator-side converter and a grid-side converter; a DC excitation module including a plurality of DC-DC converters; and a control module, controlling or switching any DC-DC converter working normally, and controlling excitation switch turning ON or turning OFF.

Abstract: A converter circuit with short-circuit protection can include a plurality of phase legs having a series connection of normally-on switches, between voltage rails of a DC voltage link, a DC link capacitor, and AC voltage connection points between the normally-on switches. A phase-to-phase short-circuit protection circuit includes a parallel connection of a resistive component and a controllable switch. The phase-to-phase short-circuit protection circuit including a first terminal connected to an AC voltage connection point and a second terminal forms an input or an output of the converter circuit; and a controllable switch is connected in series with the DC link capacitor. Upon lack of control of the normally-on switches the controllable switch of the at least one phase-to-phase short-circuit protection circuit and the controllable switch of the phase leg short-circuit protection circuit are adapted to be controlled to a non-conductive state.

Abstract: Power converter modules and parallel conversion systems are presented in which the modules are provided in a rollable enclosure having AC and DC electrical connections, and an interior including a switching circuit with switching devices individually connected between a corresponding AC node and a corresponding DC node for operation as either a rectifier or an inverter and an internal filter circuit with inductors individually connected between a corresponding AC node of the switching circuit and a corresponding AC electrical connection, with a built-in blower or fan to cool the filter circuit during operation.