Abstract: A multiple inverter with neutral line inductor and an active power filter system are disclosed. In the disclosure, the multiple inverter comprises at least two inverter units connected in parallel, the midpoint of the direct current bus in each inverter unit is connected to the neutral line N through the respective neutral line inductor. The multiple inverter can suppress the ripple produced by the neutral line current without increasing the direct current bus capacitor.

Abstract: A DC to DC converter system, includes inverter circuitry having a first and a second switch, the inverter circuitry further configured to generate a first and a second gate control signal, the signals configured to open and close the first and second switch, respectively, and generate an AC signal from a DC input signal. The system further includes transformer circuitry configured to transform the AC signal into a sinusoidal AC signal, second stage circuitry configured to rectify the sinusoidal AC signal to a DC output signal, and hybrid control circuitry configured to modulate the first and second gate control signals, wherein the modulation comprises pulse frequency modulation (PFM) and pulse width modulation (PWM).

Abstract: Embodiments of an adapter are disclosed that include a transformer with a primary coil coupled to an H-bridge. The H-bridge is controlled by a control circuit that controls a voltage across the primary coil using the H-bridge, and the control circuit is configured to control the H-bridge so that during each of one or more intervals, a first voltage pulse is applied across the primary coil in a start direction, wherein the start direction alternates between a first direction and a second direction each interval. Then, a direction of subsequent voltage pulses across the primary coil is alternated between the first direction and the second direction a predetermined number of times. After the predetermined number of times, a last voltage pulse is applied across the primary coil; then, voltage across the primary coil is reduced to zero for a predetermined time.

Abstract: A DC/DC converter includes two input terminals for a DC input voltage, two output terminals for a DC output voltage, an inverter converting a DC voltage into an AC voltage, and a rectifier converting an AC voltage from the inverter into a DC voltage between a first one of the input terminals and a first one of the output terminals. At least one galvanically isolating element is arranged between the output of the inverter and the input of the rectifier, and a capacitance is coupled between the output terminals. The inverter converts a partial DC voltage, being smaller than the full DC input voltage, across a capacitance between the second one of the input terminals and the second one of the output terminals.

Abstract: A control method to be implemented in a power converter, the power converter including an inverter module controlled by a control rule that makes it possible to determine a control voltage to be applied to an electrical load on the basis of a reference control voltage. The control method includes determining a correction value to be applied to the reference control voltage, the correction value being determined from a first filtered voltage obtained by filtering a voltage that is representative of the real measured voltage, and a second filtered voltage obtained by filtering a voltage that is representative of the reference control voltage.

Abstract: A method and apparatus for generating AC power. In one embodiment, the apparatus comprises a DC/AC inversion stage capable of generating at least one of a single-phase output power, a two-phase output power, or a three-phase output power; and a conversion control module, coupled to the DC/AC inversion stage, for driving the DC/AC inversion stage to selectively generate the single-phase output power, the two-phase output power, or the three-phase output power based on an input power to the DC/AC inversion stage.

Abstract: A power converter including a resonant circuit is controlled by pulse width modulation (PWM) of a switching circuit to control current in the resonant circuit near the frequency of the resonant circuit (a null-immittance criterion) in order to control current and voltage at the output of the resonant circuit. Further control of voltage can be performed by PWM of a switching circuit at the output of the resonant circuit such that centers of the duty cycles of respective switches for the output of the resonant circuit are substantially synchronized and substantially symmetrical about centers of said duty cycles of respective switches at the input of the resonant circuit. Thus, operation of the converter is substantially simplified by using only PWM, a wide range of input and output voltages can be achieved and the converter circuit can be configured for bi-directional power transfer.

Abstract: In a multiphase electrical power assignment, a processor: receives instructions to connect a bi-directional power device to a multiphase premise power source; determines that the power device is to be coupled to a target phase's phase connection; confirms that the power device is not coupled to any phase connections; and couples the power device to the phase connection, where the power device's power signal is synchronized with the phase connection's power signal. When the power device is in a connected state, the processor: issues a command to place each phase connection switch in an open state; in response to confirming that the phase connection switches are in the open state, issues commands to the power device so that a power signal of the power device will be synchronized with the target phase; and closes the phase connection switch corresponding to the target phase.

Abstract: A power supply that performs output PWM control and PSM control. The PWM control is performed when the required output is such that a control signal is set with a larger ON pulse width than a predetermined narrow pulse width allowing for sufficient activation of switching elements in an inverter circuit and an auxiliary switching circuit. The PSM control is performed when the required output is such that the control signal for each switching element is set with a smaller ON pulse width than the predetermined narrow pulse width. The PSM control adjusts the phase of a control pulse signal so that the ON pulse is fixed to the predetermined narrow pulse width.

Abstract: Provided is a power conversion device capable of detecting a short circuit failure and protecting from the same securely. The power conversion device includes: a three-phase bridge type power conversion circuit including a semiconductor switch including a first main terminal, a second main terminal, and a control terminal; a control circuit for controlling an operation of the semiconductor switch; and a voltage detection circuit for monitoring a voltage between DC terminals of the power conversion circuit, in which the control circuit has a protection function of turning off the semiconductor switch if the voltage between the DC terminals of the power conversion circuit, which is detected by the voltage detection circuit, is lower than a predetermined value for a predetermined period of time or longer.

Abstract: An isolated DC to DC converter including zero voltage switching and a current doubler. Current sensors are located between a positive input of the DC to DC converter and a current doubler is used in an output stage of the DC to DC converter in order to enable more accurate current sensing in a main transformer to prevent saturation of the transformer core and provide increased efficiency and power output with lower electromagnetic noise. The input of the DC to DC converter is isolated from the output of the DC to DC converter, and the DC to DC converter may be used in a hybrid or all-electric vehicle to provide an accessory bus from a power source of the vehicle.

Abstract: A power conversion system according to the present invention includes: an inverter circuit unit that converts a direct current power supplied from a direct current source into an alternating current power, the direct current power being supplied to the inverter circuit through a contactor that conducts and interrupts the direct current; a capacitor that smoothes the direct current power; a discharge circuit unit that is connected to the capacitor in parallel, and that includes a discharge resistor for discharging a charge stored in the capacitor and a switching element for the discharge resistor, being connected in series to the discharge resistor; a voltage detection circuit unit that detects voltage between both terminals of the capacitor; a first discharge control circuit that includes a first microcomputer, and that outputs a control signal to control switching of the switching element for discharging; and a second discharge control circuit that outputs an interruption signal to interrupt the switching el

Abstract: A control method and apparatus are provided to convert a DC voltage into alternating voltage. The apparatus includes a first inverter and a second inverter to generate a first alternating voltage and a second alternating voltage, respectively. Also included is an interphase transformer to combine these alternating voltages in parallel to obtain a first resulting alternating voltage. The apparatus also includes a third inverter and a fourth inverter to generate a third and fourth alternating voltage, respectively. These are combined to form a second resulting alternating voltage. The second resulting alternating voltage is displaced in phase approximately 180° in relation to the first resulting alternating voltage.

Abstract: A DC-to-DC converter has a leading full-bridge inverter and a lagging full-bridge inverter for receiving a DC input and producing respective AC output voltages. A full-wave rectifier circuit rectifies the AC output voltages to produce a rectified output voltage, which is filtered by a current doubling output filter circuit to produce a DC output voltage. A master phase-shift controller and a slave phase-shift controller respectively provide first and second control signals to the leading full-bridge inverter and third and fourth control signals to the lagging full-bridge inverter to regulate the DC output voltage by changing a phase of the second and fourth control signals with respect to the first and third control signals below a predetermined DC output voltage, and by changing a phase of the third and fourth control signals with respect to the first and second control signals above the predetermined threshold.

Abstract: A converter section (2) includes three pairs of switching elements (Srp, . . . , Stn), each pair having two switching elements connected in series between two direct current links (L1, L2), and phases of an input three-phase alternating current are connected to nodes between the series-connected switching elements one by one. Each of the switching elements (Srp, . . . , Stn) is made of a transistor having a bipolar structure. The control unit (5) controls the switching elements (Srp, . . . , Stn) such that line voltages between a reference phase, which is one of the phases of the input three-phase alternating current, and each of the other phases are output to the two direct current links (L1, L2) on a time division basis. The control unit (5) applies a predetermined gate voltage to one or more of the switching elements (Srp, . . . , Stn) to which a reverse bias is applied.

Abstract: A control device for a switching circuit of a resonant converter having a direct current at the output, the switching circuit having at least one half bridge of at least first and second transistors connected between an input voltage and a reference voltage. The half bridge is adapted to generate a periodic square wave voltage to drive the resonant circuit of the resonant converter; The control device has a circuit to proportionally generate a first voltage to a switching period, and a circuit adapted to limit the voltage at the ends of a capacitor between a reference voltage and the first voltage, and a further circuit structured to control the switching off of a first or second transistor at the time instant in which the voltage across the capacitor has reached the first voltage.

Abstract: A three-level inverter includes a set of series-connected capacitors connected in parallel to a direct-current power supply; two arms connected in parallel to an output of the direct-current power supply and each having an alternating-current output terminal; and a control section having a neutral voltage controller determining a three-phase voltage correction command based on a neutral voltage and voltage of the direct-current power supply, having a coordinate converter converting the three-phase voltage correction command to a voltage correction command on d-q axis, and suppressing voltage variations at the neutral point by correcting a voltage command on d-q axis based on the d-q voltage correction command. The neutral point is connected to one grounded phase of a three-phase grounded power system. The alternating-current output terminals are connected to respective non-grounded phases of the power system. A power conditioner includes the three-level inverter.

Abstract: Processes, machines, and articles of manufacture that may management power conversion as provided. This may include circuit topology or management that serves to improve power conversion efficiency from a DC waveform to an AC waveform. This circuit topology or management may include considering and managing the voltage across a DC-link capacitive bus and the phase angle output of an AC waveform in order to influence or improve power conversion characteristics or efficiency.

Abstract: A method and apparatus for generating AC power. In one embodiment, the apparatus comprises a DC/AC inversion stage capable of generating at least one of a single-phase output power, a two-phase output power, or a three-phase output power; and a conversion control module, coupled to the DC/AC inversion stage, for driving the DC/AC inversion stage to selectively generate the single-phase output power, the two-phase output power, or the three-phase output power based on an input power to the DC/AC inversion stage.

Abstract: A power supply topology is used in which a transistor is provided on the side of an output node of a rectifying circuit. An inductor is provided on the side of a reference node, a resistor is inserted between the transistor and the inductor, and one end of the resistor is coupled to a ground power supply voltage of a PFC circuit. The PFC circuit includes a square circuit which squares a result of multiplication of an input voltage detection signal and feedback information (output voltage of an error amplifier circuit). The PFC circuit drives on the transistor when a detection voltage developed at the resistor reaches zero, and drives off the transistor when the detection signal reaches an output signal of the square circuit.

Abstract: Aspects of the invention can include capacitors which series-divide the voltage of a DC power source, an inverter circuit formed by bridge-connecting semiconductor switching elements to which diodes are antiparallel-connected, and bidirectional switches connected between a connection point of the capacitors and the AC output terminals of the inverter circuit. When the voltage of the DC power source is lower than a prescribed value, the inverter circuit can be caused to operate as an ordinary three-phase inverter, and when the voltage of the DC power source is higher than a prescribed value the inverter circuit can be caused to operate as a V-connected inverter, and when caused to operate as a V-connected inverter, a halted phase can be switched in sequence according to line voltages or output currents.

Abstract: A controller of a power converter including an inverter that includes plural semiconductor switching elements. The controller suppresses an error between a voltage command and an inverter output voltage and responds to a voltage command at a high speed. The controller includes a voltage command generator that generates a voltage command signal and a switching pattern calculator that calculates and outputs, based on the voltage command signal, a switching pattern of a synchronous PWM system in which an average value of an inverter output voltage matches the voltage command signal.

Abstract: Methods and systems for controlling a reactive power contribution to reactive power flowing in an electricity distribution network, so as to optimize this reactive power flow are described. A reactive power characteristic of electrical power flowing in the electricity distribution network is detected at a power device. The reactive power characteristic relates to a reactive power component of electricity flowing in the network. On the basis of the detected reactive power characteristic a reactive power contribution to the electricity distribution network is controlled so as to adjust a value of the detected reactive power characteristic. This enables individual power consumption and/or provision devices to react autonomously to local variations in the electricity distribution network, and to provide a reactive power contribution, to drive the detected reactive power characteristic towards a desired value.

Abstract: A power conversion apparatus includes a comparison circuit which compares a determination element related to a loss in the power converter with a switching reference value and outputs a determination instruction when a difference has occurred between them, a determination circuit which outputs a two-level operation switching instruction when the determination element is greater than or equal to the switching reference value, and a switching circuit which, when having received a two-level operation switching instruction, turns off the alternating-current switch and turns on the valve devices in the arm sequentially, thereby bringing the power converter into a two-level operation state.

Abstract: A power supply device includes: a magnetic-coupling-type multi-phase converter having first and second chopper circuits that respectively adjust respective currents flowing in first and second reactors magnetically coupled to each other, and performing voltage conversion between a DC power supply and a load; and a control circuit. The control circuit includes a determination unit and a current control unit. The determination unit determines whether the temperature of the power supply is lower than a reference temperature. In the case where the power supply temperature is lower than the reference temperature, the current control unit uses a value determined by adding an offset amount to a detected value of the reactor current to set a duty command value for the first chopper circuit and uses a detected value of the reactor current to set a duty command value for the second chopper circuit.

Abstract: The present invention concerns a projection system for providing a distributed manifestation within an environment. The projection system includes a data generator for generating a plurality of data sets of associated state data and spatial coordinate data. The projection system also includes a projector in communication with the data generator for receiving the data sets. The projector is provided with a signal generating module for generating a plurality of electromagnetic signals, and a projecting module for projecting each of the electromagnetic signals towards a target location within the environment. The projection system also includes a plurality of receiving units distributed within the environment, each receiving unit having a receiver for receiving one of the electromagnetic signals when the receiving unit is positioned in the corresponding target location, each receiving unit being adapted to perform a change of state in response to the state data.

Abstract: A method and apparatus for controlling an inverter includes operating the inverter in a one of a normal run mode or a pulse mode depending on one or more criteria. When operating in the pulse mode, the inverter generates a sinusoidal output pulse waveform including a plurality of pulses having a determined pulse width. The pulse width is less than a half-wave period of a full-cycle sinusoidal waveform and may be determined as function of, for example, the output power of the inverter, a grid voltage, and/or other criteria.

Abstract: A boost converter including two or more inductors coupled to an input DC power source and to switches that can each be modulated with a modulation signal to control the output power of the boost converter. Two or more of the modulation signals have a relative phase other than 360° divided by the number of switches.

Abstract: An H-bridge control circuit comprises an input stage, comparator stage, inverter stage. The operation of the H-bridge can be controlled by a single analog input signal provided by a feedback stage. Shoot-through protection is provided for the H-bridge circuit through the inclusion of a dead gap determined by inputs to the comparator stage. The dead gap can be adjusted, allowing for adjustment of the precision operation of the load. The H-bridge can be used to drive a bi-directional load such as, for example, a Peltier conditioner.

Abstract: A DC-to-AC power converter is disclosed which provides current regulated three-phase AC outputs and very high conversion efficiencies. The converter sinks power from an external DC current source and steers that current directly into two phases of a three-phase load by using complementary semiconductor switches in disparate half-bridges of a six-pole bridge. The steering switch selection rotates every 60° to direct current into the two phases with the largest voltage differential at any given time. The remaining half-bridge acts as a high-frequency, bi-directional current source to balance the three-phase load currents. This topology and control method significantly reduces power conversion losses. Prior art converters first convert “soft” DC sources to voltage sources and then to AC current sources. The invention eliminates the need for large filter inductors and DC bus capacitors used in prior art converters. The invention is optimized for photovoltaic, utility-grid-interactive applications.

Abstract: An automatic breaker apparatus for the USB power supply, comprising a manual switch module, a relay, a high frequency transformer, a PWM power source master control module, a drive module, a signal filter module, an MCU master control module, a lighting instruction module and at least one USB power output end. When a user presses down the manual switch module, the relay becomes conductive, thus causing the electronic apparatus connected to the USB power source input end to be charged, and determining through the MCU master control module whether the electronic apparatus is using the electric current based on the pulsed filter signal outputted by the signal filter module thereby driving the relay to disconnect and also starting the lighting instruction module to generate light.

Abstract: A power inverter may include a transformer serving as an isolation barrier. The power inverter may include a first controller on one side of the isolation barrier. The first controller may encode the frequency of an input voltage of the transformer with one or more operating conditions of a direct current power supply electrically coupled to the inverter. As second controller on the other side of the isolation barrier may determine a frequency associated with an output voltage of the transformer. The second controller may decode the frequency associated with the output voltage of the transformer to determine the encoded operating conditions.

Abstract: An induction heating apparatus is capable of stop heating without excessively boosting output voltages of a booster circuit and a power factor correction circuit. The induction heating apparatus includes a boosting function unit, an inverter circuit, and a booster circuit controller. The boosting function unit includes a power factor correction circuit and a booster circuit, and boosts an input direct-current power to a direct-current voltage having a peak value larger than the peak value of the input direct-current power by turning on/off a switching element. The inverter circuit includes a heating coil, and inputs the direct-current voltage output by the boosting function unit to generate a high frequency current in the heating coil by turning on or off a different switching element. The booster circuit controller stops a boosting operation of the boosting function unit without a prescribed delay from the stop of an operation of the inverter circuit.

Abstract: A power semiconductor device comprises: high side and low side switching elements; high side and low side drive circuits; a bootstrap capacitor supplying a drive voltage to the high side drive circuit and having a first terminal connected to a connection point between the high side switching element and the low side switching element and a second terminal connected to a power supply terminal of the high side drive circuit; a bootstrap diode having an anode connected to a power supply and a cathode connected to the second terminal and supplying a current from the power supply to the second terminal; a floating power supply; and a bootstrap compensation circuit supplying a current from the floating power supply to the second terminal, when the high side drive circuit turns ON the high side switching element and the low side drive circuit turns OFF the low side switching element.

Abstract: A grid-connected inverter apparatus includes: an inverter 50 for converting a DC output based on power generated from a power generation equipment 100 into an AC; a DC voltage measuring unit 40 for measuring a DC voltage on a DC input side of the inverter 50; a grid interconnection switch 70 having two independent relay switches 71, 72 each corresponding to phases of a grid power system 110 to which the inverter 50 is connected; and a control unit 90 for controlling the two relay switches 71, 72, such that the control unit 90, after opening the two relay switches 71, 72, changes the relay switch 71 such that the opening control is changes to closing control and, based on a change in the DC voltage measured by the DC voltage measuring unit 40 before and after the changing control, determines whether the relay switch 72 is faulty.

Abstract: The noise generated from a power converter is suppressed by increasing the noise frequency to a level not lower than the maximum frequency of the human audible range. To obtain the frequency of an output current harmonic component as a noise source which has exceeded the maximum frequency of the human audible range, it is adequate to determine that the frequency of a driving carrier wave for the individual converter cells in the power converter, in which the phases of the carrier wave for the converter cells are mutually shifted by a given value between the converter cells, meets the following equation.

Abstract: The disclosure relates to a method for operating an inverter that includes at least one bridge assembly that is actuated in a modulated manner for supplying electrical power to an energy supply network. Initially, the inverter is operated by the unipolar actuation of the at least one bridge assembly and the energy supply network is monitored for the presence of a network fault. If a network fault is detected, the inverter is operated at least at intervals by the bipolar actuation of the at least one bridge assembly. The disclosure further relates to a network fault-tolerant inverter which is equipped for carrying out the method.

Abstract: Embodiments of the invention relate to a power system for converting direct current (“DC”) power on a DC bus into alternating current (“AC”) power with a regulated voltage output and for feeding the AC power to an electrical system which may include a power utility or an electric grid, for example. A power conversion control system is used for controlling the power conversion and for maintaining the DC bus voltage (“DC voltage”) at a certain level.

Abstract: An inverter with soft switching is used for a high step-up ratio and a high conversion efficiency. The inverter includes an isolation voltage-quadrupling DC converter and an AC selecting switch. The isolation voltage-quadrupling DC converter includes an active clamping circuit. By a front-stage converter circuit, a continuous half-sine-wave current is generated. By a rear-stage AC selecting switch, the half-sine-wave current is turned into a sine-wave current. Thus, electricity may be supplied to an AC load or the grid. The circuit is protected by isolating the low-voltage side from the high-voltage side. The conversion efficiency is high. The leakage inductance is low. The switch stress is low. The inverter is durable and reliable. Hence, the inverter is suitable for use in a photovoltaic system to increase the total conversion efficiency.

Abstract: An electric power converter apparatus includes an inverter circuit having a plurality of upper arm elements and a plurality of lower arm elements, a feedback controlling module calculating a voltage command value in order to control an output from the inverter circuit in a feedback control manner and a compensating module compensating the voltage command value with a compensation amount and outputting a compensated voltage command value. Each of the plurality of upper arm elements and the plurality of lower arm elements is operated to switch over based on a control signal that is set according to the compensated voltage command value and a dead time. The compensation amount is set by the compensating module in order to compensate a fluctuation in the output current due to the dead time.

Abstract: A power regeneration apparatus includes a power conversion unit, an AC reactor, a voltage detecting unit, a phase detecting unit, a drive control unit for controlling the power conversion unit based on a phase detection value, and a reactive current component detecting unit. The phase detecting unit detects the phase of the AC power supply. The reactive current component detecting unit detects a reactive current component of a current. The drive control unit includes a phase correction section. The phase correction section corrects the phase detection value based on the reactive current component.

Abstract: An inverter and an active power filter system have been disclosed in the invention, so that the application range of the inverter under the occasions of different capacitor requirement can be widened, the cost can be decreased, and the efficiency can be improved. The technical scheme is: an auxiliary capacitor module can be added on the traditional inverter structure and connected in parallel selectively with the capacitor in the inverter. In a system without connecting an external auxiliary capacitor module, the value of capacitance can be designed to be smaller to satisfy the application under normal occasions. If the device operates under the occasions having large harmonic current or having large neutral line current, the ripple current on the capacitor will be larger so that large capacitance will be required to satisfy the life requirement, therefore, the problem can be solved by a method of installing an auxiliary capacitor module.

Abstract: An AC converter includes: a switching section, which converts the input AC voltage in response to a control signal and which outputs the converted voltage to a phase that has been selected in accordance with the control signal; a filter section, which filters out high frequency components from the converted voltage, thereby converting the converted voltage into the output AC voltage; and a switching control section, which performs a pulse density modulation on a phase-by-phase basis and in response to a reference signal with the frequency f1, which is associated with the output AC voltage of each phase, synchronously with a zero cross of the input AC voltage, thereby generating the control signal according a pulse generation status by the pulse density modulation and the polarity of the input AC voltage and sending out the control signal to the switching section.

Abstract: Provided is a drive device for an alternating current motor which performs vector control on sensorless driving of the alternating current motor in an extremely low speed region without applying a harmonic voltage intentionally while maintaining an ideal PWM waveform. A current and a current change rate of the alternating current motor are detected, and a magnetic flux position inside of the alternating current motor is estimated and calculated in consideration of an output voltage of an inverter which causes this current change. The current change rate is generated on the basis of a pulse waveform of the inverter, and hence the magnetic flux position inside of the alternating current motor can be estimated and calculated without applying a harmonic wave intentionally.

Abstract: A multiple inverter and an active power filter system are disclosed in the invention, said multiple inverter can decrease the volume and harmonics, increase the efficiency and decrease the cost, and can be applied to various occasions. The technical scheme is: the filter assembly in the multiple inverter is installed at the output inductor of the multiple inverter for filtering the harmonics.

Abstract: An apparatus includes an inverter including a high-side switch coupled to a low-side switch, the inverter generating a time-varying drive current from a plurality of drive control signals, a positive rail voltage, and a negative rail voltage wherein controlling the switches to generate the time-varying drive current produces a potential transitory overshoot condition for one of the switches of the inverter; a drive control, coupled to the inverter, to generate the drive control signals and to set a level of each of the rail voltages responsive to a plurality of controller signals; and a controller monitoring one or more parameters indicative of the potential transitory voltage overshoot condition, the controller dynamically adjusting, responsive to the monitored parameters, the controller signals to reduce a risk of occurrence of the potential transitory voltage overshoot condition.

Abstract: In a high frequency antenna switch module, an I/O interface generates various control signals for controlling a switch module on the basis of a system data signal and a system clock, a decoder generates a switch control signal SWCNT for controlling a switch in response to a control signal CNT in the control signals, a timing detector for switch-ports switching generates a switch-port switching detection signal t_sw in response to the switch control signal, a frequency control signal generator generates frequency control signals ICONT and CCONT in response to the signal t_sw, and a negative voltage generation circuit generates a negative voltage output signal NVG_OUT while switching the frequency of the clock signal generated in the negative voltage generation circuit to different frequencies in response to signals ICONT and CCONT. The switch switches the paths among the plural switch ports in response to the signals SWCNT and NVG_OUT.

Abstract: A correction-term adder 1 compares a maximum value max(V*) with an absolute value of a minimum value min(V*). The correction-term adder 1 selects a signal 1?max(V*) when the maximum value max(V*) is larger than the absolute value of the minimum value min(V*), on the other hand, selects a signal ?1?min(V*) when the absolute value of the minimum value min(V*) is larger than the maximum value max(V*). Thereby, a signal of correction amount ? is calculated. Moreover, the correction-term adder 1 produces a triangular-wave-shaped signal k(max(V*)+min(V*)) by multiplying a gain k by an addition signal max(V*)+min(V*) of the maximum value max(V*) and the minimum value min(V*). This triangular-wave-shaped signal k(max(V*)+min(V*)) is synchronized with the correction amount ?.

Abstract: Provided is a variable frequency drive and a rotation speed searching apparatus for an induction motor incorporated therein. The rotation speed searching apparatus is featured by scanning the rotor frequency of the induction motor and determining either the error between a detected DC-bus voltage and a set DC-bus voltage or the error between a detected output current and a set output current, so that the rotation speed of the induction motor can be searched out.

Abstract: Disclosed is a bi-directional battery power inverter (1) comprising a DC-DC converter circuit element (3) to which the battery (2) can be connected in order to generate an AC output voltage from a battery (2) voltage in a discharging mode while charging the battery (2) in a charging mode. The inverter (1) further comprises an HF transformer which forms a resonant circuit along with a resonant capacitor (6). In order to increase the efficiency of said battery power inverter, the transformer is provided with two windings (11, 12) with a center tap (20) on the primary side, said center tap (20) being connected to a power electronic center-tap connection with semiconductor switches (21, 31) while a winding (13) to which the resonant capacitor (6) is serially connected provided on the secondary side.