Abstract: Control systems for a multi-level diode-clamped inverter and corresponding methods include a processor and a digital logic circuit forming a hybrid controller. The processor identifies sector and region locations based on a sampled reference voltage vector V* and angle ?e*. The processor then selects predefined switching sequences and pre-calculated turn-on time values based on the identified sector and region locations. The digital logic circuit generates PWM switching signals for driving power transistors of a multi-level diode-clamped inverter based on the turn-on time values and the selected switching sequences. The control system takes care of the existing capacitor voltage balancing issues of multi-level diode-clamped inverters while supplying both active and reactive power to an IT load. Using the control system, one can generate a symmetrical PWM signal that fully covers the linear under-modulation region.

Abstract: An inverter, a power unit and a power module applied to the inverter are provided. The power unit includes a first package module, a second package module, and a third package module, each including two switch transistors that are complementary to each other. Since the first package module and the second package module are arranged in one half of the inner space of the power unit, and the third package module is arranged in the other half of the inner space of the power unit, the control terminal of each of the three package modules is arranged on a side of the half for arranging the package module that is away from the other half. Thus, the power unit can adopt a small-sized packaging structure without changing a layout of driver boards, thereby reducing the cost of the power unit and the inverter.

Abstract: Method of controlling a multi-level inverter having inputs connected to a gate drive unit controlling the inverter and an output connected to a load, the multi-level inverter capable of generating a PWM voltage signal having three or more modulation levels, the inverter powered by a voltage supply and comprising at least one neutral point (NP), the method comprising operating the multi-level inverter in a standard modulation pattern having three or more modulation levels when one or more parameters representative of neutral point stability each have a value within a first range indicative of a high neutral point stability, and operating the multi-level inverter with a two-level modulation pattern when said one or more parameters representative of neutral point stability each have a value within a second range indicative of a low neutral point stability, the first range separated from the second range by a threshold value.

Abstract: An isolated primary side switched converter (100) has a galvanic isolation stage (105) separating a primary side (101) and a secondary side (103). The secondary side winding (107) is connected to a rectification circuit and has a center tap. A first terminal (T1), a second terminal (T2) and a third terminal (T3) are provided for connecting one or more LED loads (LED1, LED2) to the secondary side (103) of the converter (100). The rectification circuit (109) is configured to set the first terminal (T1) at a positive electrical polarity and to set the second terminal (T2) at a negative polarity. The third terminal (T3) is electrically connected to the center tap. One or two LED loads can be connected between T1 and T3 (low voltage) and T2 and T3 (low voltage), or in one embodiment a single LED load can also be connected between T1 and T2 (high voltage).

Abstract: A power supply apparatus includes a storage battery and supplies a voltage from the battery to an electric load. The power supply apparatus includes first and second energizing paths connected in parallel between the battery and the load, a first switch making the first energizing path conductive and interrupting the first energizing path, and a second switch making the second energizing path conductive and interrupting the second energizing path. The power supply apparatus includes a first drive circuit that operates when a voltage is supplied and drives the first switch, a second drive circuit that operates when a voltage is supplied and drives the second switch into a conductive state in a case where the first switch is driven into a conductive state by the first drive circuit, first and second supply paths respectively supplying a voltage to the first and second drive circuits.

Abstract: This application provides a power rectification method and apparatus, to supply power to a load by using a power supply capacity gap formed by a communications power that is at an existing network site, thereby achieving a capacity increase. The method includes: obtaining a total input current of each of three phase lines; and when it is determined that a total input current of at least one of the three phase lines is greater than a total input current threshold corresponding to the at least one phase line, adjusting a rectifier connected to the at least one phase line to reduce a total input power of the at least one phase line, so that the total input current of the at least one phase line is less than or equal to the total input current threshold corresponding to the at least one phase line.

Abstract: A method controls switching states of a multi-level converter with multiple modules. Each module has: terminals on a first and second side; controllable switches; and an energy store in series with a first switch in a first connection between the terminals. A second switch is arranged in a connection between the terminals. The control of the switching states is divided into a real-time and offline part. In the real-time part, for each time step: a voltage level is allocated to a voltage requirement; a total switching state is determined in a first switching table for the voltage level; and the total switching state is passed on as a control signal to the switches. In the offline part: a second switching table is calculated, resulting in accordance with a minimization of a cost function.

Abstract: A four-level rectifier may include an output, a first capacitor, a second capacitor, a third capacitor, and three phases. The first, second, and third capacitors may be connected in series. The output may be connected between the first capacitor and the third capacitor. Each of the three phases may include an input, a first diode, a second diode, a first switch, a second switch, and a third switch. The first diode may be connected between the input and the first capacitor. The second diode may be connected between the input and the third capacitor. The first switch may be connected between the input and the second switch and the third switch. The second switch may be connected to the first capacitor and to the second capacitor. The third switch may be connected to the second capacitor and to the third capacitor.

Abstract: For a serial multiplex inverter in which each phase includes cells connected serially, wherein each cell includes switching elements and is configured to output a level of +1 (ON), a level of zero (OFF), and a level of ?1 (ON) as output levels by operation of the switching elements, a control device includes a switching load distribution control section. This control section is configured to: store information about an ON-output duration of each of the cells and information about an OFF-output duration of each of the cells; for a shift pattern from ON to OFF in the cells, put OFF a gate signal for one of the cells whose ON-output duration is the longest of the cells; and for a shift pattern from OFF to ON in the cells, put ON a gate signal for one of the cells whose OFF-output duration is the longest of the cells.

Abstract: A conversion device includes: an inductor connected to the AC power grid; a first-stage converter configured to output a bus voltage based on the AC power grid; a second-stage converter configured to convert the bus voltage into an output voltage to the load; and a filtering network, wherein a first resistance-capacitance circuit is disposed between the first and third terminals of the filtering network, a second resistance-capacitance circuit is disposed between the second and third terminals of the filtering network, the first terminal of the filtering network is connected to the AC power grid, the second terminal of the filtering network is connected to the bus or the second terminal of the second-stage converter, and the third terminal of the filtering network is grounded through a first capacitor.

Abstract: A conversion device includes: an inductor electrically connected to the AC power grid; a first-stage converter configured to output a bus voltage according to the AC power grid, wherein the first-stage converter includes an N-level alternating current-direct current (AC-DC) converter, and the N-level AC-DC converter includes a plurality of switch bridge arms, wherein both an upper bridge arm and a lower bridge arm of each of the plurality of switch bridge arms of the N-level AC-DC converter include a plurality of semiconductor devices connected in series, and a rated withstand voltage Vsemi of each of the semiconductor devices is greater than or equal to (Vbus*?)/((N?1)*Nseries*?); and a second-stage converter configured to convert the bus voltage into an output voltage to supply energy to the load.

Abstract: A system includes a first inverter connected between a dc power source and an input terminal of a first leg of a coupled inductor, a second inverter connected between the dc power source and an input terminal of a second leg of the coupled inductor, a third inverter connected between the dc power source and an input terminal of a third leg of the coupled inductor, and an output filter connected between the coupled inductor and an ac power source, wherein output terminals of the first leg, the second leg and the third leg of the coupled inductor are connected together and further connected to the output filter.

Abstract: Control systems for a multi-level diode-clamped inverter and corresponding methods include a processor and a digital logic circuit forming a hybrid controller. The processor identifies sector and region locations based on a sampled reference voltage vector V* and angle ?e*. The processor then selects predefined switching sequences and pre-calculated turn-on time values based on the identified sector and region locations. The digital logic circuit generates PWM switching signals for driving power transistors of a multi-level diode-clamped inverter based on the turn-on time values and the selected switching sequences. The control system takes care of the existing capacitor voltage balancing issues of multi-level diode-clamped inverters while supplying both active and reactive power to an IT load. Using the control system, one can generate a symmetrical PWM signal that fully covers the linear under-modulation region.

Abstract: The present disclosure relates to a micromechanical displacement logic, signal propagation system that makes use of first and second bistable elements, and first and second mounting structures arranged adjacent opposing surfaces of the first bistable element. A plurality of pivotal lever arms are used to support the first bistable element in either one of two positions of equilibrium. A support structure and a compressible flexure element disposed between the support structure and the first mounting structure apply a preload force to the first mounting structure, which imparts the preload force to the first bistable element. The first bistable element is moveable from one of the two stable equilibrium positions to the other in response to an initial signal applied thereto.

Abstract: A method for improving the modulation index using an intelligent battery pack, in which method a battery pack includes a plurality of freely interconnectable energy modules. An energy module has at least one energy cell and at least two switches, and in which method series or parallel interconnection of a respective energy module with at least one adjacent energy module of the battery pack is implemented by a controller. A terminal voltage of the battery pack, which terminal voltage results from the respective interconnection, is adjusted in accordance with a respectively prespecified load demand on at least one N-phase electrical machine. The terminal voltage is connected as an input voltage to at least one multi-stage inverter, and an N-phase alternating current for supplying a respective N-phase electrical machine is formed by the at least one multi-stage inverter on the basis of a level of the input voltage.

Abstract: An apparatus utilizing additive interleaved switchmode (PWM) power conversion stages, having minimal or no output filter, to achieve high bandwidth or even ideally instantaneous power conversion. The additive process may involve voltage stacking of isolated PWM converters, which are interleaved in time, or may involve a single input power supply and inductively combining output currents of PWM power converters interleaved in time, with either additive circuit having minimal or no output filtering. This circuit may overcome limitations for the frequency of feedback control loops once thought to be physical limitations, such as, fundamental switching frequency, output filter delay and the Nyquist criteria.

Abstract: A system comprises a plurality of inverter units having inputs connected to a power source and a coupled inductor comprising a plurality of windings and coupled between the plurality of inverter units and an output filter, wherein each winding of the plurality of windings has a first terminal connected to an output of a corresponding inverter unit and second terminals of the plurality of windings are connected together.

Abstract: A method and device for operating a brushless electric motor, having windings controlled by an inverter using six switches. The inverter includes three outputs that are associated with the windings of the electric motor. A respective power semiconductor switch is arranged between the outputs of the inverter and the windings, and wherein a detection unit detects defective switches, a measuring unit measures the voltage at the outputs of the inverter, and a motor angle position sensor determines the motor angle position arc. The invention further relates to a device for operating a brushless electric motor. The inverter is switched off after a defective switch has been detected, such that no additional power is introduced in the windings of the electric motor. The motor angle position sensor consecutively opens the power semiconductor switches in a predetermined motor angle position.

Abstract: A system and method for jetting a viscous material includes an electronic controller and a jetting dispenser operatively coupled with the electronic controller. The jetting dispenser includes an outlet orifice and a piezoelectric actuator operatively coupled with a movable shaft. The jetting dispenser is under control of the electronic controller for causing said piezoelectric actuator to move the shaft and jet an amount of the viscous material from the outlet orifice. The electronic controller sends a waveform to the piezoelectric actuator to optimize control of the jetting operation.

Abstract: A plurality of anchor points at which a curve to be estimated passes sequentially through are set. Four anchor points which are successional are selected from the plurality of anchor points. First and second control points are set based on the selected anchor points. Quadratic Bezier curves connecting between the selected anchor points are calculated based on the selected anchor points and the first or second control point. Coordinate values of the curve to be estimated are estimated based on the quadratic Bezier curves.

Abstract: A system comprises a first T-type inverter connected to a dc power source, a second T-type inverter connected to the dc power source, wherein the second T-type inverter is configured to operate with a first phase shift from the first T-type inverter, a third T-type inverter connected to the dc power source, wherein the third T-type inverter is configured to operate with a second phase shift from the second T-type inverter, a coupled inductor having a first input, a second input and a third input connected to the first T-type inverter, the second T-type inverter and the third T-type inverter respectively and an output filter coupled to the output of the coupled inductor.

Abstract: The invention relates to an electric drive system with an n-phase electric machine, n>1, having at least two multiphase winding strands; a first inverter, the output connections of which are connected to the phase connections of a first of the multiphase winding strands of the electric machine; a second inverter, which is connected in parallel to the first inverter and the output connections of which are connected to the phase connections of a second of the multiphase winding strands of the electric machine; and a DC voltage source, which has a plurality of battery modules connected in series and a first output connection of which is connected to a first input connection of the first inverter and second output connection of which is connected to a first input connection of the second inverter.

Abstract: A radiation-hardened reference circuit includes a precision voltage reference circuit for generating a current-controlling voltage at first and second terminals, a driver circuit for receiving the current-controlling voltage at first and second terminals and for generating an output reference voltage, and a differential sampling circuit having first and second input terminals coupled to the first and second terminals of the voltage reference circuit, and first and second output terminals coupled to the first and second terminals of the driver circuit.

Abstract: A method and apparatus for a three port converter with independent dual input comprising: a first DC port for coupling a first half-bridge circuit of the three-port converter to a first external DC line, a second DC port for coupling a second half-bridge circuit of the three-port converter to a second external DC line, wherein the second half-bridge circuit is decoupled from the first half-bridge circuit, and an AC port for coupling to an external AC line, wherein (i) the first half-bridge circuit and the second half-bridge circuit are operated as a full H-bridge during a full-bridge operating mode, and (ii) the first half-bridge circuit or the second half-bridge circuit is operated as a half H-bridge during a half-bridge operating mode.

Abstract: A power conversion system comprising a plurality of modules each having an input and an output and being connected in series. Each module is connected to at least one DC power source that supplies power to the module. Voltage control circuitry provided within each of the modules to vary the voltage supplied between the input and the output between a maximum module voltage and a minimum module voltage. A control unit in communication with the voltage control circuitry of each of the modules varies the voltage supplied across the input and output of each of the modules such that the total voltage across the series connected modules forms an AC signal or a rectified version of an AC signal.

Abstract: Multilevel inverters, power cells and bypass methods are presented in which a power cell switching circuit is selectively disconnected from the power cell output, and a bypass which is closed to connect first and second cell output terminals to selectively bypass a power stage of a multilevel inverter, with an optional AC input switch to selectively disconnect the AC input from the power cell switching circuit during bypass.

Abstract: The scalable cascaded Z-source inverter is able to interface flexibly different distributed renewable energy sources or storages in wide voltage change range, such as wind power, solar power, battery, fuel cell, Ultra-capacitor and so on. The invention facilitates the AC 1 MHz frequency output; therefore high power density can be reached. Z-source network is integrated in each inverter module to wide system operation range, improve high system efficiency, and enhance high system reliability. The invention is applied for PV system to verify the performance.

Abstract: An example, overvoltage protection device includes a switch and a surge protection device that is selectively activated by actuating the switch. The switch is actuated in response to a voltage. An example method of absorbing an overvoltage includes sensing a voltage, and selectively activating a surge protection device in response to the sensed voltage.

Abstract: The invention concerns a voltage source converter (26) comprising a group of phase legs, at least three connection terminals (AC1, AC2, AC3, DC+, DC?) for connecting the phase legs to power transmission elements, a first group of cells (C1p1, C2p1, C1n1, C2n1, C1p2, C2p2, C1n2, C2n2, C1p3, C2p3, C1n3, C2n3) in each phase leg and a second group of cells (C3p1, C3n1, C3p2, C3n2 C3p3, C3n3). The cells (C1p1, C2p1, C1n1, C2n1, C1p2, C2p2, C1n2, C2n2, C1p3, C2p3, C1n3, C2n3) in the first group are only capable of providing unipolar voltage contributions to the converter and connected for only being capable of such unipolar voltage contributions, while the cells (C3p1, C3n1, C3p2, C3n2 C3p3, C3n3) in the second group are connected to the corresponding cells of the first group and arranged to have bipolar voltage contribution capability.

Abstract: Automatic voltage regulation is shown involving full wave rectifying a power signal and generating a reference corresponding to an operating voltage level, line sampling the power signal and comparing it to the reference to generate a line sync signal synchronized to the power signal. Producing 90° out of phase signals synchronized to the line sync signal with a PLL locked onto the line sync signal that outputs a phase error signal. Generating a quadrature signal from the phase signals. Sampling the peaks of the rectified power signal using the quadrature signal to produce a control signal. Subtracting the error signal and damping signal from the reference to produce a duty cycle modulation signal. The duty cycle modulation signal controls a duty cycle of a field voltage control signal that oscillates at a predetermined frequency. The field voltage control signal is low-pass filtered to produce the damping signal.

Abstract: A control section generates a quasi-sine wave with a plurality of gradation voltages including power supply voltages from DC power supplies with different voltages and one or more potential differences between two of the power supply voltages. Specifically, the control section generates the quasi-sine wave by, in a time range where a sine wave voltage is at two gradation voltages, generating a PWM signal with one gradation voltage set at a low level and the other gradation voltage set at a high level. The timing for switching the PWM signal is determined using an intersection between a sine wave and a triangular wave in the time range where the sine wave voltage is at two gradation voltages, where the triangular wave is generated with one gradation voltage set at a low level and the other gradation voltage set at a high level.

Abstract: Disclosed are various embodiments for a power stage that can drive various types of loads. The power stage includes a first capacitor and a second capacitor that are coupled to the load. The power stage also includes switches that are operable in a first power stage state and a second power stage state. When the switches are in the first power stage state, the first capacitor discharges to the load, and the second capacitor charges. When the switches are in the second power stage state, the second capacitor discharges to the load, and the first capacitor charges.

Abstract: A method is disclosed for controlling single-phase DC/AC converters, along with a converter arrangement having at least two single-phase DC/AC converters. A controller is provided which can control the at least two single-phase DC/AC converters, and an isolation transformer, wherein outputs of the at least two single-phase DC/AC converters are cascade-connected with each other and an input of the isolation transformer. The controller is configured to control the at least two single-phase DC/AC converters to deliver power from their inputs to their outputs by turns.

Abstract: An apparatus for harvesting solar power includes a photovoltaic array for generating a DC voltage; a discharge circuit for causing the DC voltage to decay from a first value to a second value; and an inverter circuit for transforming an output voltage from the discharge circuit into an AC voltage.

Abstract: A method for setting a desired output voltage of a power supply branch of a controllable energy store, for controlling and supplying electrical energy to an n-phase electric motor, where n?1. The controllable energy store has n parallel power supply branches, which each have at least two serially connected energy storage modules including at least one electrical energy storage cell having an assigned, controllable coupling unit; are connected to a reference bus on one side; and are connected to phases, respectively, of the electric motor on the other side. At least one coupling unit is controlled by pulses so that the arithmetic mean of the output voltage of a power supply branch corresponds to the desired output voltage. The energy storage cells respectively assigned to the coupling unit are switched into the respective power supply branch for a pulse duration, and are bypassed during a pause time.

Abstract: A method of controlling a motor is provided. The method may determine one of a switching period, a fundamental cycle, and a current target per phase leg of the motor having at least one high voltage transition point; determine a dwell period to be enforced at the transition point between an engagement of a first switch of the phase leg and an engagement of a second switch of the phase leg where each of the first switch and the second switch may be selectively engageable between a first state and a second state; engage the first switch from the first state to the second state at the transition point; and engage the second switch from the first state to the second state after the transition point and upon expiration of the dwell period.

Abstract: The present invention provides an electric circuit wherein a multi-phase bridge is connected in series with a plurality of single-phase bridges. The multi-phase bridge is composed of a plurality of 3-level diode clamped legs, while the single-phase bridges each is composed of two 3-level diode clamped legs. The present invention also provides control strategy for synthesizing multi-level voltage waveforms from output voltages of the multi-phase bridge and the plurality of single-phase bridges.

Abstract: Disclosed is an inverter having improved power conversion efficiency. The inverter (200) converts direct current power supplied from a plurality of direct current power supplies (V1, V2) having different voltages into alternating current power. The inverter (200) is provided with a control unit (20). The control unit (20) generates modified sine waves using a power supply voltage (E1) of the power supplied from the first direct current power supply (V1), a power supply voltage (E2) of the power supplied from the second direct current power supply (V2), and a potential difference (E1?E2) between the two power supply voltages. The control unit (20) generates the modified sine waves by controlling H bridge circuits provided for the direct current power supplies (V1, V2), respectively.

Abstract: The invention relates to converters for converting a DC input voltage a DC or an AC output voltage. The converters have a parasitic inductance. The converters comprise at least one switching element connected to an input terminal for providing a first voltage at an output terminal. In order to allow temporarily storing, in a capacitor, energy induced by the parasitic inductance when switching OFF the switching element, a first series circuit of a diode and a capacitor is provided in the converter, wherein the diode is coupled to the one input terminal. An active circuit coupled in parallel with the diode enables controlling the release of temporarily stored energy from the capacitor of the first series circuit.

Abstract: The present disclosure relates to a load-segmentation-based 3-level inverter and method for controlling same. Three-level inverter includes: multiple capacitors charged with voltages divided from a DC input voltage; top switch having one end connected with positive terminal of one of multiple capacitors; bottom switch having one end connected with negative terminal of one of multiple capacitors; multiple legs each including a first switch connected to the other end of top switch and a second switch connected to the other end of bottom switch with the first and second switches connected; multiple diodes connected in series forwardly from the other end of bottom switch to the other end of top switch and having interconnect points connected to a contact between the multiple capacitors; and multiple loads having connected terminals at a contact between the first and second switches of each of the legs and a contact between the multiple diodes.

Abstract: The invention relates to a DC to AC converter circuit. In particular, the invention relates to a half-bridge inverter for converting a DC to an AC voltage. The half-bridge inverter for converting a DC input voltage to provide an AC output voltage at an output terminal, comprising a first switching circuit connected to at least one input terminal and to the output terminal and configured to provide a high or a low voltage level at the output terminal; a second switching circuit connected to the output terminal and configured to provide a connection to an intermediate voltage level, the intermediate voltage level being between the high and the low voltage level; and wherein the second switching circuit is further connected to the at least one input terminal allowing the second switching circuit to provide the high or the low voltage level at the output terminal.

Abstract: A distributed power supply system in which no simultaneous disconnection from the system occurs when a system voltage momentarily drops is provided. It includes an inverter circuit that converts a direct current power generated by a direct current power supply and that supplies the alternating current power to an alternating current power supply power system, and an inverter control circuit for carrying out PWM control of the inverter circuit, wherein the inverter control circuit includes a three-phase voltage command signal generation unit, that is configured of a three-phase fundamental wave signal generation unit that generates three-phase fundamental wave signals from two phase components of voltage detected by a voltage detector, and a third harmonic signal generation unit that adds together third harmonic components of respective phases, having a predetermined amplitude, generated based on the three-phase fundamental wave signals.

Abstract: An exemplary medium voltage system includes a multilevel converter connected to a grid connection. The multilevel converter is configured for converting a first multiphase current provided at the grid connection into a second current. The system includes a common mode filter, which, for each phase of the first current, includes a phase filter connected to the respective phase. Each phase filter is connected to a common filter star point which is connected to ground, includes an inductance and a capacitance connected in series, and includes a resistance connected in series with the capacitance such that the inductance and the resistor are connected in parallel. The common mode filter includes an impedance between the common filter star point and the ground.

Abstract: A method and apparatus are provided for operating a converter circuit, which includes at least two phase modules each having first and second subconverter systems, which include power semiconductor switches. The switches of the first and second subconverter systems are driven by first and second drive signals, respectively. To enable dimensioning a capacitive energy store of the converter circuit to be independent of a desired current at an output connection of the converter circuit, for each phase module, the first and second drive signals are respectively formed from a voltage signal across inductances and a switching function for the switches of the first and second subconverter systems, respectively. The switching functions are formed by a voltage signal corresponding to the voltage at the output connection and a selectable reference signal. The voltage signals are selected to be in phase with the voltage at the output connections of the phase modules.

Abstract: The present invention provides an apparatus for controlling a multiphase multilevel voltage source inverter. The apparatus includes a signal-generating unit and a converter. The signal-generating unit responds to an input signal to produce a switching strategy control signal and a duration timing control signal corresponding to the switching strategy control signal. The converting unit responds to the switching strategy control signal and the duration timing control signal to produce a switching signal. The voltage source inverter responds to the switching signal to generate a multiphase-and-multilevel AC voltage output.

Abstract: A power detection regulation device including a power detection signal generator, a power state detector and a regulated output unit is disclosed. The power detection signal generator receives the input power from an external power supply and generates a power detection signal. The power state detector generates a power state signal based on the power state derived from the power detection signal. The regulated output unit receives the power state signal and generates a driving signal to an external electrical device in accordance with the feedback signal from the external electrical device. The power state signal is provided for the external electrical element to perform relevant processes, and the regulated output device can output the predetermined driving signal on receiving the power state signal indicating some abnormal situation in the input power so as to maintain the normal operation performed by the actuating element in the external electrical device.

Abstract: In a method for optimizing a space vector pulse width modulation, a voltage is connected to a load, by combining discrete switching states of a plurality of switches to control the load, the load being switched to zero potential by two of the switching states. In the case the maximum degree of control is increased, during a pulse width modulation period, at least one of the switching states, that switches to zero potential, is omitted.

Abstract: A Voltage Source Converter of M2LC-type has a series connection of switching cells (7), in which each switching cell has on one hand at least two semiconductor assemblies connected in series and having each a semiconductor device of turn-off type and a free-wheeling diode connected in parallel therewith and on the other at least one energy storing capacitor (20). The series connection of switching cells has one first end (61) connected to a direct voltage pole (5) on high voltage potential and an opposite end (62) connected to a phase output (10) of the converter. An arrangement (70) is configured to connect the phase output (10) to another said pole (6) on neutral voltage potential on a direct voltage side of the converter and to deliver voltage pulses to said phase output being both positive and negative with respect to said neutral potential.

Abstract: A distributed power supply system in which no simultaneous disconnection from the system occurs when a system voltage momentarily drops is provided. It includes an inverter circuit that converts a direct current power generated by a direct current power supply and that supplies the alternating current power to an alternating current power supply power system, and an inverter control circuit for carrying out PWM control of the inverter circuit, wherein the inverter control circuit includes a three-phase voltage command signal generation unit, that is configured of a three-phase fundamental wave signal generation unit that generates three-phase fundamental wave signals from two phase components of voltage detected by a voltage detector, and a third harmonic signal generation unit that adds together third harmonic components of respective phases, having a predetermined amplitude, generated based on the three-phase fundamental wave signals.

Abstract: An apparatus and method for driving a motor of an air conditioner are disclosed. A method for driving a motor of an air conditioner includes driving the motor in response to a predetermined speed command, sequentially detecting first and second mechanical angles in response to the speed command or a reference speed being spaced apart from the speed command by a predetermined range, calculating a maximum speed mechanical angle corresponding to a maximum speed ripple of the motor on the basis of the detected first and second mechanical angles, and compensating for load torque of the motor on the basis of the calculated the maximum speed mechanical angle. As a result, the speed ripple is decreased during the constant speed operation.