Abstract: A gate driving circuit includes a control power; a transformer having a primary winding and a secondary winding; a first switching element; a second switching element; a rectifying element; and a capacitance element, wherein the first switching element is connected between the control power and one end of the primary winding, and the second switching element is connected to the other end of the primary winding, wherein one end of the capacitance element is connected to either one of the one end and the other end of the primary winding, and wherein, when one of the first switching element and the second switching element is turned on, the capacitance element is charged by the control power, and when the other of the first switching element and the second switching element is turned on, the capacitance element is discharged.

Abstract: Control systems, methods and power conversion systems are presented for reducing common mode voltages in AC motor loads driven by inverter PWM control using switching sequences with only active vectors where a first vector of each switching sequence differs by one phase switching state from a last vector of a switching sequence of an adjacent sector, along with enhanced deadtime compensation and reflected wave reduction techniques in providing pulse width modulated switching signals to a switching inverter.

Abstract: A two-level or multi-level inverter are supplied with a positive auxiliary voltage (Ug+) and a negative auxiliary voltage (Ug?). A bootstrap technique provides a first positive auxiliary voltage and a first negative auxiliary voltage from the supplied potentials. The bootstrap technique provides at least one additional negative auxiliary voltage to a switch driver of at least one semiconductor switch from the first negative auxiliary voltage. At the start up of an inverter, the inverter can perform a startup sequence to provide auxiliary voltages to the respective auxiliary voltage inputs of the switch drivers by turning the power semiconductors sequentially on and off.

Abstract: A power converter circuit includes output terminals configured to receive an external AC voltage. At least one series circuit has at least two converter units. Each converter unit includes input terminals configured to be coupled to a DC power source. Output terminals provide an AC output current. The at least one series circuit is connected between the output terminals of the power converter circuit. A voltage measurement circuit is connected between the output terminals of the power converter circuit and configured to provide at least one measurement signal that includes information related to phase and frequency of the external AC voltage. At least one of the converter units is configured to receive the at least one measurement signal and is configured to regulate the generation of the AC output current dependent on the at least one measurement signal.

Abstract: Power conversion systems and methods are provided for operating a multi-phase inverter to drive a load while mitigating reflected waves, in which one or more PWM modulating signals are selectively adjusted if at least one of the phase signals or values is transitioning into or out of an over-modulation range outside a pulse width modulation carrier waveform range.

Abstract: A control circuit for a voltage converter including a power switch for providing power to a load in accordance with an embodiment of the present application includes a driver circuit operable to provide a first control signal to the power switch to turn the power switch on and off such that a desired voltage is provided to the load, an output terminal connected to the driver circuit and operable to connect the driver circuit to the power switch; and a controller operable to control the driver circuit. The output terminal operates as an input terminal to receive external data under predetermined conditions, and the controller controls the driver circuit based on the external data.

Abstract: An exemplary non-isolated DC-DC converter for a solar power plant, can be adapted to connect to a full-bridge inverter. The converter includes positive and negative input terminals, and positive and negative output terminals. A plurality of switches, diodes, inductors and capacitors are connected in a circuit configuration to the input and output terminals. A control means is connected to the circuit for controlling the switching of a first, second, and third switch between an open and closed state.

Abstract: A method of connecting a photovoltaic device to an AC power grid through an inverter includes monitoring a DC voltage at an input of an inverter, and activating the inverter when the monitored DC voltage exceeds a first predetermined threshold. The method further includes synchronizing an output voltage of the inverter with a grid voltage, connecting an output of the inverter to the AC power grid upon synchronization if the monitored DC voltage exceeds second predetermined threshold, and deactivating the inverter if a detected power being fed through the inverter falls below a predetermined power threshold while maintaining the connection between the output of the inverter and the AC power grid. Lastly, the method includes disconnecting the output of the deactivated inverter from the grid if the monitored DC voltage falls below a third predetermined threshold. Further, an apparatus that performs such functionality is also provided.

Abstract: A power factor correction (PFC) system includes a comparison module, an adjustment module, a compensation module, and a duty cycle control module. The comparison module measures N currents having different phases, and generates (N?1) comparisons based on the N measured currents, wherein N is an integer greater than one. The adjustment module determines (N?1) time advance adjustments based on the (N?1) comparisons, respectively. The compensation module generates N compensated versions of an input alternating current (AC) line signal based on the input AC line signal, a sinusoidal reference signal, and the (N?1) time advance adjustments, wherein the sinusoidal reference signal is synchronized to the input AC line signal in phase and frequency. The duty cycle control module controls PFC switching based on the N compensated versions of the input AC line signal.

Abstract: Aspects of the invention can provide a control method of a power converter that is capable of preventing increase of electromagnetic noise that are caused by simultaneous change of the states of power semiconductor switching elements of the power converter. State changes of ON/OFF pulses that are input to power semiconductor switching elements are detected, and, when the timings of the state changes of any two of the ON/OFF pulses match each other, the state change of either one of the ON/OFF pulses, of which state changes match each other, is delayed.

Abstract: A comparator compares a voltage of a node into which electric current flows from a system of a first voltage and a reference voltage for maintaining the node at a second voltage. A step-up-type DC-DC converter receives the voltage of the node which is input to the comparator, increases the voltage to a voltage higher than the first voltage, and applies the voltage to the system of the first voltage. According to the comparison of the comparator, when the voltage of the node is higher than the reference voltage, the step-up-type DC-DC converter activates a step-up function, and when the voltage of the node is equal to or less than the reference voltage, the step-up-type DC-DC converter deactivates the step-up function.

Abstract: A bipolar pulsed power supply is provided in which, while effectively restricting the rise in current at the time of arcing which directly leads to the generation of splashes and particles, the occurrence of overvoltage at the time of polarity reversal is prevented. The power supply has a bridge circuit constituted by switching elements SW1 through SW4 connected to positive and negative DC outputs from a DC power supply source. The operation of the switching elements is controlled to output in a bipolar pulsed mode at a predetermined frequency to a pair of electrodes which come into contact with a plasma. There is provided an output-characteristics-switching circuit which switches the output such that, when outputting to the electrodes, the output to the electrodes has initially constant-voltage characteristics and subsequent output to the electrodes has constant-current characteristics.

Abstract: Systems and methods are provided for delivering energy from an input interface to an output interface. An electrical system includes an input interface, an output interface, an energy conversion module coupled between the input interface and the output interface, and a control module. The control module determines a duty cycle control value for operating the energy conversion module to produce a desired voltage at the output interface. The control module determines an input power error at the input interface and adjusts the duty cycle control value in a manner that is influenced by the input power error, resulting in a compensated duty cycle control value. The control module operates switching elements of the energy conversion module to deliver energy to the output interface with a duty cycle that is influenced by the compensated duty cycle control value.

Abstract: A power converter enhances conversion efficiency from DC power to AC power. A first chopper circuit chops DC voltage from a photovoltaic panel at a system frequency producing a first square-wave whose voltage level changes positively. A second chopper circuit chops the first square-wave at a frequency double the system frequency producing a second square-wave whose voltage level changes negatively and adds the first square-wave and the second square-wave to produce a third square-wave that changes positively and negatively in a sine-wave manner. A third chopper circuit charges and discharges by chopping the third square-wave at a third frequency fixed by timing according to a difference between the third square-wave and a sine-wave voltage. PWM control is performed on the charge and discharge outputs such that the difference is corrected, producing a sine-wave voltage that continuously changes positively and negatively. A spike noise of an output voltage is suppressed.

Abstract: A non-contact electric power transmission circuit according to an embodiment of the invention includes an electric power transmission circuit and an electric power receiving circuit. The electric power transmission circuit includes a full bridge circuit and a resonant type full bridge circuit. A direct-current power supply is used as an input of the full bridge circuit, the full bridge circuit includes two sets of switching elements, two switching elements being connected in series in each set of the switching elements, a drive circuit alternately feeds a pulse signal to gates of the switching elements to perform switching of the direct-current input in the full bridge circuit, and a serial resonant circuit of a resonant capacitor and an electric power transmission coil is connected to an output of the full bridge circuit in the resonant type full bridge circuit. The electric power receiving circuit includes an electric power receiving coil and a rectifying and smoothing circuit.

Abstract: An isolated switched mode power supply (SMPS) is disclosed. The SMPS comprises a switching controller to generate start-up and operational switching control signals. The SMPS further includes a transformer, having a primary winding, and a full-bridge drive circuit to drive the primary winding. The full-bridge drive circuit comprises a first switching element, a boot-strap dnving circuit, and a second switching element. The switching controller is further used to start up isolated SMPS by determining a duty cycle for operational control signals and generating the start-up switching control signals.

Abstract: A power conversion device includes an inverter circuit converting DC power into AC power and including switching devices constituting upper and lower arms, a control circuit controlling the switching devices, a drive circuit driving the switching devices by a signal from the control circuit, and an insulated power supply circuit supplying power to the drive circuit. The control circuit controls a power supply voltage to be outputted from the power supply circuit to the drive circuit. The drive circuit drives the switching devices and based on a carrier frequency and the power supply voltage. The power supply circuit includes a feedback output circuit through which the voltage outputted to the drive circuit is outputted to a power supply control IC. The feedback output circuit includes a dummy load circuit which controls the voltage to be outputted to the power supply control IC based on a change of the carrier frequency.

Abstract: A microinverter is provided for converting DC energy from a PV panel into a grid-compatible AC signal. A first plurality of switching elements is coupled between a DC energy source and a primary winding of a transformer. A second plurality of switching elements is coupled to a secondary winding of the transformer. Current sensors sense real time converter parameters including a DC input, an AC output, and a primary current. A digital controller determines an operating mode for the converter based on a DC input signal, with the controller further including a switch signal generator circuit configured to adjust switching states. The switch state adjustments are based on the operating mode, real time converter parameters which include the DC input signal, an AC signal for output to a grid, a primary current, and a desired shape for the AC output signal waveform.

Abstract: Methods, systems, and devices are described for both power and control signal transmission through a single coupled inductor. A current driver generates a cyclical current signal on a primary winding of a coupled inductor, to induce a voltage signal at the secondary winding corresponding to the cyclical current signal. A rectifier module is coupled with the secondary winding and configured to rectify the signal induced at the secondary winding. A control timing signal module is coupled with the primary winding and configured to induce voltage pulses on the secondary winding, the induced voltage pulses having an insubstantial impact on the output of the rectifier module. A switching module coupled with the secondary winding is configured to receive the voltage pulses and control a switching signal for a power switch coupled with the output of the rectifier and provide power to a load coupled with the output of the rectifier.

Abstract: A method and a control device control a switching device for providing a resonant circuit with a switching voltage for generating a resonant current in order to provide a required output power at an output of a resonant power converter.

Abstract: This patent document discloses power electronic transformers having a high-frequency link. An example apparatus include a transformer having a primary winding and a secondary winding, the transformer is configured to receive a primary power signal having a first frequency, a primary converter configured to selectively oscillate polarity of the primary windings with respect to the secondary windings at a second frequency, the second frequency substantially substantially higher than the first frequency, a secondary converter coupled to the secondary winding, the secondary converter configured to provide a load power signal using a high frequency power signal generated using the secondary winding. The secondary converter can be configured to reduce current flow in the primary winding when the polarity of the primary winding is switched, the reduced current follow is configured to reduce disturbances resulting from leakage inductance of the transformer.

Abstract: A power converter includes a bus capacitor connected between a positive line and a negative line of a power supply bus and multiple switching legs connected between the positive line and the negative line of the power supply bus. Each switching leg includes two field-effect type transistors connected in series. The power converter also includes a first switch connected to the positive line of the power supply bus, upstream of the bus capacitor, a second switch connected to the positive line of the power supply bus, downstream of the bus capacitor, and a controller that controls the first switch and the second switch.

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: Disclosed herein is a torque control method for a high-speed Switched Reluctance Motor (SRM), which controls a torque in the high-speed operation of a 2-phase SRM. In the torque control method for a high-speed SRM, a positive torque (T*mA) of an active phase (A phase) of the two phases of the SRM is compensated for based on a negative torque attributable to an inactive phase (B phase) of two phases during a compensation control enable interval (ENA) ranging from a time point at which the active phase (A phase) is turned on to a time point at which tail current of the inactive phase (B phase) remains. Accordingly, the present invention can remarkably reduce a torque ripple occurring in high-speed operation mode in consideration of the influence of a negative torque attributable to tail current.

Abstract: The configurations of an H-bridge circuit and a controlling method thereof are provided in the present invention. The proposed circuit includes an H-bridge having a first and a second bridge arms, each of which has a middle point, and a bidirectional switch connected to the two middle points, a bootstrap circuit providing a bootstrap voltage, a driving circuit receiving the bootstrap voltage and driving the bidirectional switch, and an energy compensation circuit coupled to the H-bridge, the bootstrap circuit and the driving circuit, and providing a compensation energy to the bootstrap circuit.

Abstract: To provide an electrical junction box that can maintain a stable assembly condition between a box main body and a cover member, even if locking mechanisms are not provided on a whole periphery of the electrical junction box. An electrical junction box includes a box main body and a cover member. One of the box main body and the cover member is provided on at least a single of side portions of the one peripheral wall with a locking mechanism. An elastic rib that protrudes from an inner peripheral surface of the one peripheral wall at one of the side portions is pressed onto a fitting projection piece. A side portion is provided with a support wall that is opposed to and spaced apart from the inner peripheral surface. The fitting projection piece is held in a space between the inner peripheral surface and the support wall.

Abstract: A power conversion device includes a first inverter circuit and a second inverter circuit, a capacitor, and a microcomputer. The microcomputer switches a control operation, according to the steering state of a steering wheel, between a first state where a first duty center value is shifted to be lower than an output center value and a second duty center value is shifted to be higher than the output center value, and a second state where the first duty center value is shifted to be higher than the output center value and the second duty center value is shifted to be lower than the output center value. This can reduce a difference in heat loss between FETs while reducing the ripple current of the capacitor.

Abstract: A power conversion system as an aspect of the present invention includes: a power converter using a plurality of legs to convert inputted electric power and output powers in a plurality of phases, each leg including upper and lower arms; and a controller 30 controlling the upper and lower arms of each leg to control pulse current flowing through the leg. The controller 30 calculates a duty ratio instruction of each leg in one control period for each phase and, concerning first and second legs among the plurality of legs provided for a certain one of the phases, changes the phase of the calculated duty ratio instruction so that a time period when positive pulse current flows through the first leg and a time period when negative pulse flows through the second leg overlap each other in the one control period.

Abstract: The power conversion control apparatus is for controlling a power conversion circuit in which a plurality of pairs each including a high-side switching element and a low-side switching element connected in series to each other are connected in parallel to a capacitor, and an external battery is connected to the capacitor through a relay. To discharge the capacitor, the power conversion control apparatus turns on both the high-side and low-side switching elements of at least one of the pairs to make a short circuit between both electrodes of the capacitor on condition that the relay is open.

Abstract: Photovoltaic power converter systems and methods are described. In one example, a method for use in operating a solar power converter includes sampling a DC link voltage of a DC link during a first cycle of an alternating output voltage of a second stage at one instance when the alternating output voltage is crossing zero volts in a first direction. A voltage difference a voltage difference between the DC link voltage sampled during the first cycle and a DC link voltage sampled during a previous cycle when the alternating output voltage was crossing zero volts in the first direction is determined. A DC link power is estimated based at least in part on the determined voltage difference. The AC power output by the second stage in a second cycle is controlled based at least in part on the estimated DC link power.

Abstract: A microinverter is disclosed for use in a solar power installation. The microinverter incorporates a voltage-to-current control loop that initially converts output current produced by a photovoltaic panel into a pulse width modulated output synchronized and phase-locked to the utility grid voltage. The duty cycle of that modulated output is specified by output power internally requested from the microinverter. This modulated output is converted into a full-wave rectified unipolar waveform that is converted, through a Commutator, into a bipolar AC output that is also phase-locked and synchronized to the grid voltage. The commutator uses an H-bridge composed of four FETs, with each of two diagonally-oriented pairs of these FETs being advantageously switched on substantially at zero-crossing points in the grid voltage.

Abstract: The present invention discloses a controllable rectification comprising an inverter (10), a control panel (20) and a drive panel (30). The inverter (10) may comprise three switch element groups connected in parallel. Each switch element group may comprise at least two switch elements connected in parallel. Each switch element may comprise an upper bridge-arm switch and a lower bridge-arm. The control panel (20) may generate a PWM waveform. The drive panel (30) may generate a drive voltage according to the PWM waveform to drive the upper bridge-arm switch and the lower bridge-arm switch of each switch element to conduct or break respectively, and to make the upper bridge-arms of the same switch element group to conduct or break simultaneously, and to make the lower bridge-arms of the same switch element group to conduct or break simultaneously. The present invention further discloses an electric motor comprising the same.

Abstract: The present invention includes: a plurality of switching elements connected in series and connected between two ends of a DC power supply; a first control circuit to alternately turn on and off the switching elements in response to a constant oscillation frequency signal; a series circuit including a primary winding of a transformer and a capacitor connected together in series, and being connected to a connecting point between the switching elements, and to an end of the DC power supply; a rectifying/smoothing circuit to rectify and smooth a voltage in a secondary winding of the transformer thereby to output a DC voltage; a control switching element connected to two ends of the primary or secondary winding of the transformer; and a second control circuit to control the DC voltage at a predetermined voltage by turning on and off the control switching element.

Abstract: A method and circuit for controlling a resonant DC/DC converter which adjusts an output voltage by changing a turn-on frequency of input switch devices of a resonant circuit of the converter. The method extends the range of the output voltage of the resonant circuit by adjusting the duty ratio of the switch devices based on the feedback signal of the load circuit. The method and circuit uses two modes to control resonance of the DC/DC converter-frequency modulation and frequency modulation plus pulse width modulation. Frequency modulation is used when the operating frequency of the power supply is low. Frequency modulation plus pulse width modulation is used when the operating frequency of the power supply is too high.

Abstract: This inverter circuit includes first and second switching elements and an output transformer which is provided with a first primary winding connected in series between said first and second switching elements, and also with a secondary winding for obtaining an output voltage. The inverter circuit is further provided with a first voltage supply, a second voltage supply, and a control unit. The first voltage supply applies voltage to said first switching element via said first primary winding. And the second voltage supply applies voltage to said second switching element via said second primary winding. The control unit turns said first switching element and said second switching element alternatingly ON and OFF. This inverter circuit also includes first and second regeneration snubber circuits for regenerating the charge charged into snubber capacitors.

Abstract: A pulse width modulated current control method and system architecture may achieve the high performance of an advanced current control for full-bridge stages, in terms of accuracy, error, speed, and frequency response, but with a reduced complexity in terms of used analog circuits, being comparable with that of an elementary peak current control. The only analog blocks used may be a current sense transducer, i.e. a series resistor or a sense-FET, and a comparator for the current sensing while the rest of the control circuitry is digital.

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 control system controls a multiphase rotating machine by a 120° energization process and a PWM process. In the 120° energization process, respective ones of switching elements of a high side arm and switching elements of a low side arm of a power conversion circuit are turned on. In the PWM process, the switching elements of the power conversion circuit turn on/off so that two phases that are connected to the switching elements that are in the on-state are alternately rendered conductive to the high potential side input terminal and the low potential side input terminal of the power conversion circuit.

Abstract: We describe a modular adjustable power factor renewable energy inverter system. The system comprises a plurality of inverter modules having a switched capacitor across its ac power output, a power measurement system coupled to a communication interface, and a power factor controller to control switching of the capacitor. A system controller receives power data from each inverter module, sums the net level of ac power from each inverter, determines a number of said capacitors to switch based on the sum, and sends control data to an appropriate number of the inverter modules to switch the determined number of capacitors into/out of said parallel connection across their respective ac power outputs.

Abstract: The PWM signal generator of the present invention generates a first pulse waveform in which a first on-time ?T1 calculated by a first on-time calculator (401) is used as an on-duration, and a second pulse waveform in which a second on-time ?T2, calculated by a second on-time calculator (402) when a preset delay time has elapsed from the start of the calculation of the first on-time ?T1, is used as an on-duration. Also, a PWM signal generator (413) generates a PWM signal on the basis of a composite pulse in which the generated first pulse waveform and second pulse waveform are combined, and the first on-time calculator (401) calculates the first on-time ?T1 at the end of the composite pulse waveform.

Abstract: A converter has a network-side and a load-side power converter that are connected together on the DC side in an electrically conductive manner. An upper and a lower valve branch of each phase module, respectively, of the load-side power converter has at least one two-poled subsystem. At least one multiphase network-controlled power converter is provided as the network-side power converter. In this way, a converter is obtained, in particular an intermediate voltage circuit converter for intermediate voltages, which combines a simple and cost-effective feed circuit on the network side with a modular multilevel converter on the load side.

Abstract: Techniques are generally described for a converter including a PLL and a pulse deleting circuit. The pulse deleting circuit is configured to delete a pulse from one of the inputs to the PLL when a filtered output in the PLL falls below a first reference level and an unlocked state of the PLL is detected in response to a phase lag of one of the first and second pulse inputs with respect to the other. The pulse deleting circuit may also be configured to delete one pulse of the other of the first and second pulse inputs when the filtered output exceeds a second reference level and the unlocked state of the PLL is detected in response to a phase lead of the one of the first and second pulse inputs with respect to the other.

Abstract: A phase-controlled power supply is disclosed. The power supply includes a power conditioner with an input configured to connect to an external source of electrical power, the power conditioner being configured to provide conditioned power on its output. The power supply also includes a transformer having a primary winding and a secondary winding, and a switching module coupled between the output of the power conditioner and to the primary winding of the transformer. The switching module has two modes of operation and a control signal input configured to accept a first control signal. The switching module includes a switching element configured to connect the power conditioner output to the primary winding of the transformer. The switching module operates in the first mode when the first control signal is in a first state, switching the first switching element at a first frequency and first duty cycle.

Abstract: A power converter includes at least two power conversion sections operating in parallel. The power converter receives a variable input power and generates an AC output voltage. When the power source is generating enough power to supply a DC voltage to the power converter greater than or equal to the peak magnitude of the desired AC voltage output, each power conversion section operates in parallel, converting the DC voltage to the desired AC voltage output. When the power generated by the variable power source results in a DC voltage having a magnitude less than the peak magnitude of the desired AC voltage output, the power conversion sections operate in series. One power conversion section operates as a boost converter to boost the DC voltage level to a suitable level for the second power conversion section, which generates the desired AC output voltage.

Abstract: An apparatus and method for controlling a DC-to-AC inverter is disclosed. The DC-to-AC inverter may be configured to convert DC power received from an alternative energy source to AC power for supplying an AC grid or load. The inverter may determine whether the power presently supplied by the alternative energy source is less than a predetermined amount of power and, if so, disable an output converter of the inverter. Additionally, the inverter may predict the voltage of a DC bus of the inverter at a future point in time and, if the predicted DC bus voltage is greater than a predetermined maximum DC bus voltage, enable the output converter to transfer energy from the DC bus to the AC grid to reduce the DC bus voltage.

Abstract: A torque limit section that applies limit to a torque instruction value of an electric motor such that a switching elements temperature is restricted to no more than an element upper limiting temperature includes a torque restriction section that finds a torque restriction value for restricting the torque of the electric motor in accordance with the said switching elements temperature; a torque restriction mitigation section that finds a torque restriction mitigation value for mitigating the torque limit value in accordance with the integrated value of the deviation of the element upper limiting temperature and the switching elements temperature; a first subtractor that finds a torque restriction value by subtracting the torque restriction mitigation value from the torque limit value; and a second subtractor that finds a limited torque instruction value obtained by subtracting the torque limit value from the torque instruction value and outputs this to the gate generating section.

Abstract: A method and apparatus for converting DC electricity to AC electricity, the AC electricity having a sine wave shape. DC electricity is supplied to a pulse width modulator. A pulse width modulated signal is formed from the DC electricity, the pulse width modulated signal comprising a plurality of pulses, each pulse having a duration representing an amplitude of the sine wave during an interval of the sine wave represented by the pulse, the pulse width modulated signal comprising a plurality of pulses (or a pulse train) during one sine wave period. The sine wave is generated from the pulse width modulated signal, values of the sine wave during successive sine wave intervals responsive to the duration of the pulse that represents the sine wave interval.

Abstract: The present invention relates to a control device and a control method of a high voltage inverter capable of automatically and accurately setting up neutral point information at a master controller and a plurality of cell controllers of the high voltage inverter, wherein a master controller determines information of neutral point set up to itself and performs a communication with the cell controllers each disposed at each of a plurality of U phase unit cells, a plurality of V phase unit cells and a plurality of W phase unit cells to determine the neutral point information preset on the cell controllers and to detect a cell controller set up with neutral point information different from that of the master controller, and to correct the neutral point information of the detected relevant cell controller using the neutral point information set up in the master controller, thereby operating the high voltage inverter.

Abstract: In a power converter, a voltage command signal shifting part shifts a first duty command signal such that a first duty center value related to a voltage applied to a first set of windings is shifted downwards than an output center value of a possible duty range. The voltage command signal shifting part also shifts a second duty command signal such that a second duty center value related to a voltage applied to a second set of windings is shifted upwards than the output center value. First and second shift amounts of the first and second duty center values from the output center value are varied depending on amplitude. Accordingly, ripple current of a capacitor can be decreased, and a difference in heat loss between switching elements can be minimized.

Abstract: A method for operating a single-phase, mid-frequency welding transformer formed with a transformer core having a primary coil and a secondary coil connected into a secondary circuit has several steps. The several steps include regulating a magnetic flux density (B) in the transformer core between an upper flux density threshold value (Bm) and a lower flux density threshold value (?Bm), by applying, in alteration, a first voltage (UDC) and a second voltage (?UDC) to the primary coil of the transformer, and regulating a load current (ibr) in the secondary circuit between an upper load current threshold value (ibr-zg) and a lower load current threshold value (ibr-sp), by applying, in alternation, a third voltage (0V)to the primary coil of the transformer.