Abstract: A damascene process is utilized to fabricate the segmented magnetic core elements of an integrated circuit inductor structure. The magnetic core is electroplated from a seed layer that is conformal with a permanent dielectric mold that results in sidewall plating defining an easy magnetic axis. The hard axis runs parallel to the longitudinal axis of the core and the inductor coils are orthogonal to the core's longitudinal axis. The magnetic field generated by the inductor coils is, therefore, parallel and self-aligned to the hard magnetic axis. The easy axis can be enhanced by electroplating in an applied magnetic field parallel to the easy axis.

Abstract: A method for manufacturing an inductor using a system-in-package (SIP) includes forming a first penetration electrode in a silicon substrate; depositing an insulating film on a first surface of the silicon substrate, and patterning the insulating film to form an inductor hole and a second penetration hole aligned with the first penetration hole; forming an inductor in the inductor hole and a second penetration electrode in the second penetration hole; and depositing a protective film on the insulating film and performing a back grind process such that the first penetration electrode is exposed from a second surface of the silicon substrate, the second surface being opposed to the first surface.

Abstract: An inverter device includes an inverter circuit, an inverter driving unit, and a clamp diode. The inverter circuit includes an upper arm unit and a lower arm unit connected in series. The upper arm unit and the lower arm unit include switching elements that drive a load. The inverter driving unit includes a high-withstand-voltage IC that drives the switching elements of the upper arm unit and the lower arm unit. The high-withstand-voltage IC has a first terminal for supplying a reference voltage to the lower arm unit and a second terminal for supplying a high-voltage to the upper arm unit. The clamp diode clamps a potential difference between the first terminal and the second terminal.

Abstract: A method of fabricating a coil-embedded inductor provides steps for obtaining uniform density of coil-embedded inductor. The cavity of a first die is filled with dust before being flipped, and then filled with dust a second time. The dust in the cavity is pressed only once for improving the density.

Abstract: A heating current used to inductively heat a metallic or magnetic work-piece is generated by an inverter supplied by a supply voltage. The inverter includes four switching elements arranged in an H-bridge circuit having two parallel longitudinal branches and a transverse branch. The switches are controlled so the heating current flows through the transverse branch. The diagonally opposed switching elements are switched from a conductive to a non-conductive state in a temporally staggered manner.

Abstract: It is disclosed that there is a sustaining pulse generator of a plasma display panel capable of simplifying a circuit configuration thereof. A sustaining pulse generator of a plasma display panel according to an embodiment of the present invention includes a DC converter for converting AC voltage to DC voltage; a switching part for switching the DC voltage to convert into square wave; a transformer for inducing the square wave to an output terminal thereof connected to a panel; and a rectifier for rectifying the square wave induced to the output terminal to apply to the panel.

Abstract: A power control apparatus and power control method that reduce harmonic noise produced when modulating a carrier wave frequency over predetermined cycles. A command value signal is generated for obtaining a desired output voltage, and a carrier wave is output. The frequency of the carrier wave is modulated by a desired frequency over predetermined cycles, and the desired frequency also modulates. The carrier wave is compared to a command value signal and a resulting control signal is provided to a switching unit. Harmonic noise caused by the modulation frequency can be spread, and the peak of the harmonic noise caused by the first modulation frequency can be reduced. Therefore, noise caused by a modulation frequency can be reduced.

Abstract: An apparatus and process are provided for multi-frequency induction heating of a workpiece. Switching devices are used to selectively add, remove or reconfigure capacitive elements in the circuit to change the circuit's resonant frequency, and consequently, the frequency of induction heating or melting power transfer from the power supply to the load.

Abstract: A booster circuit for a pre-drive circuit of a brushless direct current single-phase motor. When a series pair of power FETs of the drive circuit turn on, one boost control switching element of the pre-drive circuit turns on, another series pair of power FETs of the drive circuit turn off, and the other boost control switching element of the pre-drive circuit turns off. The booster circuit provides a continuous stable output voltage to the motor.

Abstract: Non-linear inductor(s) are used to reduce the percent total harmonic distortion of the harmonics in the line currents in the input side rectifier system of an ac drive system. Several constructions for the non-linear inductor(s) are described. The non-linear inductor(s) may be constructed from E and I laminations. The gap depends on the construction of the middle leg of the E laminations and may have a step with a constant spacing or a variable spacing which depends on the stacking of the laminations. Alternatively the non-linear inductor(s) may be constructed from a toriodal core that either has a step gap or a variable type gap.

Abstract: A converter circuit arrangement is disclosed for matching a variable DC voltage to a drive circuit for producing drive signals and having a three-point DC voltage intermediate circuit (2), which three-point DC voltage intermediate circuit (2) is formed by a first capacitor (3) and a second capacitor (4) connected in series with it, with one connection of the first capacitor (3) forming an upper connection (5) of the three-point DC voltage intermediate circuit (2), and the first capacitor (3) forming a center point connection (6) at the junction point with the second capacitor (4) and one connection of the second capacitor (4) forming a lower connection (7) of the three-point DC voltage intermediate circuit (2).

Abstract: A power conversion apparatus, such as an uninterruptible power supply (UPS), includes an input port, an output port, and first and second busses. An output circuit, for example, a half-leg inverter, is coupled to the first and second busses and to the output port and operative to transfer power therebetween. An auxiliary DC voltage generator circuit, for example, a battery converter circuit, is operative to generate DC voltages on the first and second busses. A multifunction rectifier circuit is coupled to the input port and to the first and second busses, the multifunction rectifier circuit operative to generate DC voltages on the first and second busses from an AC power source at the input port when the apparatus is operating in a first mode (e.g., an AC powered operational mode). The multifunction rectifier circuit is operative to control relative magnitudes of the DC voltages generated by the auxiliary DC voltage generator circuit when the apparatus is operating in a second mode (e.g.

Abstract: A drive system for driving large capacity motors includes a motor and a variable frequency drive which accepts input from a three-phase power source. The drive system includes a step-up transformer, preferably of a high-capacity three-phase type, positioned between and electrically connected to the motor and the variable frequency drive to thereby step-up voltage received from the variable frequency drive to be supplied to the motor. The transformer includes a transformer chamber formed in the transformer tank containing a cooling fluid for cooling transformer internal components. A plurality of inductors forming part of a harmonic filter are positioned within the transformer chamber such that they can be protected from the environment and simultaneously cooled with other transformer internal components by the dielectric fluid. The filter includes capacitors that are preferably mounted outside of the tank.

Abstract: Non-linear inductor(s) are used to reduce the percent total harmonic distortion of the harmonics in the line currents in the input side rectifier system of an ac drive system. Several constructions for the non-linear inductor(s) are described. The non-linear inductor(s) may be constructed from E and I laminations. The gap depends on the construction of the middle leg of the E laminations and may have a step with a constant spacing or a variable spacing which depends on the stacking of the laminations. Alternatively the non-linear inductor(s) may be constructed from a toriodal core that either has a step gap or a variable type gap.

Abstract: An H-type motor bridge coil driver circuit is implemented with an electronic switch in each leg segment of an H-shaped circuit, this bridge circuit having its side legs each connected between a power supply and ground, with the inductive load of a motor coil being connectable as the cross leg of the H-shaped circuit. An alternate current path, voltage level stabilizing element may be connected across each leg segment electronic switch. A coil excess energy storage element may be connected to the coil nodes of the circuit, through alternate current path elements and utilized to temporarily store the discharging of the excess coil energy normally available because of the lagging nature of the motor coil current. This temporary storage element then may discharge this energy back to the power supply through a passive circuit element, and reverse polarity protection is included for the power supply.

Abstract: A 3-level inverter includes a plurality of power semiconductor switching elements respectively connected in serial relation, a diode connected in reverse parallel relation with each of the plurality of power semiconductor switching element, and a plurality of snubber circuits for protecting the plurality of power semiconductor switching elements. The number of the snubber circuits is smaller by one as compared with the number of the power semiconductor switching circuits, and one of the snubber circuits is connected with a DC neutral point and AC output terminal. The one of the snubber circuits which is connected with the DC neutral point and the AC output terminal is a circuit including a capacitor connected in serial relation with a resistor.

Abstract: A thermal protection circuit arranged in an integrated circuit for protecting a power delivery is disclosed. The thermal protection circuit for protecting a power delivery circuit includes a first thermal sensing circuit exhibiting a negative temperature coefficient characteristic for sensing a temperature of the power delivery circuit and providing a first voltage, a second thermal sensing circuit exhibiting a positive temperature coefficient characteristic for transforming the temperature of the power delivery circuit to a second voltage, an amplifier electrically connected to the first voltage and the second voltage for providing a control signal, wherein the amplifier is a function of a voltage difference between the first voltage and the second voltage, and a switch electrically connected to an output of the amplifier for limiting a maximum current passing there through in response to the control signal.

Abstract: Switching devices conjointly use snubber circuits without disposing for each switching device and is interposed between a DC neutral point N and a positive terminal plate of a DC power source. A second snubber circuit is interposed between the DC neutral point N and a negative plate terminal of a DC power source. A third snubber circuit is interposed between the DC neutral point N and an AC output terminal O. The snubber circuit suppresses the rise of the voltage when each switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device when this voltage exceeds the power source voltage during the process in which the switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device or when this voltage exceeds the power source voltage during the process.

Abstract: A fault current tolerant power supply circuit having a dc power source and switching devices for inverting dc current from the source into ac load current includes a protective circuit for protecting the switching devices from overvoltage conditions when an inductive load is short-circuited. The protective circuit uses a capacitive component to absorb charge during a short circuit to protect non-conducting switching devices from an overvoltage condition.

Abstract: An uninterruptible power supply is provided that is capable of turning off an AC switch made up of thyristors as quickly as possible by using a power converter. A power is supplied from the utility power supply 3 to the load 9 through the AC switch 1 made up of antiparallelly connected thyristors. Under this condition, in the event that the power failure detection means 12 detects a power outage, if the current detection means 11a detects a current of a positive polarity, the reference sinusoidal voltage generation circuit 11 generates the high synchronous sinusoidal voltage Vref2 which is higher, by the voltage difference command value &Dgr;V, than the synchronous sinusoidal voltage Vref1 in phase with the utility power supply.

Abstract: A power converter suitable for use in an uninterruptible power supply (UPS) includes first and second voltage busses, an input port having a first terminal coupled to one of the first and second voltage busses, a neutral bus and an output terminal. A first switching circuit selectively couples a second terminal of the input port to the first and second voltage busses. A second switching circuit selectively couples the first and second voltage busses to the output terminal. A third switching circuit selectively couples the first and second voltage busses to the neutral bus. Preferably, the first, second and third switching circuits are operative to produce an AC output voltage at the output terminal from a DC input voltage at the input port such that alternating ones of the first and second terminals of the first input port are referenced to the neutral bus for successive first and second half cycles of the AC output voltage.

Abstract: An asymmetrical full bridge DC-to-DC converter comprises an asymmetrical full bridge circuit which includes main switches and auxiliary switches, a capacitor connected in series to the branch circuit of the auxiliary switches, and a transformer having a primary winding and a secondary winding. The primary winding of transformer is connected to the common point of each leg of the full bridge. A rectification circuit is connected at the secondary winding of the transformer to obtain dc voltage output. In operation, an asymmetrical control method is applied for these main switches and auxiliary switches. Main switches and auxiliary switches turn on and turn off compensatively. A linear control characteristic of output voltage to switching duty cycle and an optimal reset of the transformer core is achieved by this invention.

Abstract: A current source inverter (1) comprises a bridge circuit (2) having a plurality of bridge paths (5), in each of which a controllable power semiconductor component (6) is arranged. In the case of such an inverter, a loss in performance on account of inductance-dictated overvoltages during the turn-off of the power semiconductor components (6) is avoided by virtue of the fact that the controllable power semiconductor component (6) is avalanche-proof at least under loading in the forward direction.

Abstract: A comparator compares the voltage of a shunt resistor detected by a current detection terminal with a reference voltage and supplies a current abnormality signal to a fault circuit when the voltage of the shunt resistor is in excess of the reference voltage, so that a stop signal is supplied to a power device driving circuit and an input circuit and the power device driving circuit and another power device driving circuit stop operation of transistors respectively. The fault circuit, outputting the stop signal created by the same through a fault terminal, can also receive a stop signal output from another control circuit and supply the same to the power device driving circuit and the input circuit. Thus, internal wires are simplified in an inverter module having a protective function for a power device for miniaturizing the module.

Abstract: A power supply circuit (100) configured to control operation of a load (135) including a converter (105, 110) configured to convert a DC signal to an AC signal, a drive circuit connected to the converter (105, 110) to control operation of the converter (105, 110), and a shutdown circuit (160) connected to the drive circuit to turn off the converter (105, 110). The shutdown circuit (160) includes a diode (190) and a switch (185).

Abstract: A current source inverter (1) comprises a bridge circuit (2) having a plurality of bridge paths (5), in each of which a controllable power semiconductor component (6) is arranged.

Abstract: A piloting circuit comprises a circuit branch which is intended to be connected to a DC voltage supply source in such a way as to receive a voltage of predetermined polarity, and in which the drain-source path of a (first) MOSFET transistor intended to receive an on-off piloting signal on its gate is connected in series with the load, a current recirculation diode connected in parallel to the load, and protection devices operable to prevent damage to the MOSFET transistor and/or the diode in the event of polarity reversal of the supply voltage. The protection function is achieved of an electronic switch disposed in series with the recirculation diode and piloted in such a way as to prevent the passage of current in this diode if a supply voltage of reversed polarity with respect to the predetermined polarity is applied to the said circuit branch.

Abstract: The invention relates to a series resonant converter (1) comprising a control circuit (8) for controlling the output voltage of the converter. To improve the behavior of the converter, it is proposed that the control circuit (8) is provided for processing a first actual value (Uout), which depends on the respective converter output voltage (uout(t)) and for processing a second actual value (UC), which depends on the respective current (ires(t)) flowing through the series resonant circuit elements (C, L, R) of the converter (1), and that the control circuit (8) is provided for delivering a correcting variable (u) determining the scanning ratio of a pulse-width modulated voltage (upwm(t)) delivered to the series resonant circuit of the converter.

Abstract: A power conversion apparatus comprising a switching power module (1) for conducting power conversion in a switching manner, a plurality of smoothing capacitors (6A) for smoothing a direct-current power supply output to be applied to the switching power module (1), and a switching power module connecting wiring board (19) for establishing connection of the smoothing capacitor (6A) to the switching power module (1). A ceramic capacitor is used as the smoothing capacitors (6A). The smoothing capacitors (6A), a smoothing capacitor case (23) accommodating the ceramic capacitors and the switching power module connection wiring board (19) are integrated structurally with each other to construct a smoothing capacitor assembly (24). This smoothing capacitor assembly (24) is connected to the switching power module (1).

Abstract: A power converter includes first and second voltage busses and a neutral bus. A first switching circuit, e.g., a rectifier circuit, is operative to selectively couple an input node thereof to the first and second voltage busses. A balancer circuit is operative to selectively couple the neutral bus to the first and second voltage busses such that relative magnitudes of respective first and second voltages on the first and second voltage busses are controlled responsive to respective first and second rates at which the balancer circuit couples the first and second voltage busses to the neutral bus. A second switching circuit, e.g., an inverter circuit, is operative to selectively couple the first and second voltage busses to a load connected at an output node thereof.

Abstract: A laser power supply apparatus supplies AC power to a gas contained in a laser device by way of a pair of dielectric layers, without having to use a transformer to form a high-frequency discharge in a gas to excite the gas, to cause the laser device to radiate. The laser power supply apparatus includes an inverter having arms, each arm including high-speed semiconductor switches connected in series, for directly converting a DC high voltage from a DC power supply to a series of AC output pulses having a much higher AC voltage than the DC high voltage and supplied to the laser device by simultaneously turning on and off those high-speed semiconductor switches in each of the arms, and for furnishing the series of AC output pulses to the laser device at a pair of output terminals.

Abstract: To prevent malfunction or breakdown due to a surge voltage in a power converter for converting DC into AC or the like so as to supply electric power to a load, not only a control signal is transmitted via a level shift circuit which is provided correspondingly to each of switching semiconductor elements forming a main circuit and shifts a level of a reference potential at its output side so as to follow variations of a reference potential of the switching semiconductor element to the switching semiconductor element, but a DC control power source for supplying electric power to the level shift circuit and a negative pole of the switching semiconductor element are connected to each other through at least one of an inductor and a resistance.

Abstract: A method and system for predicting malfunctions in a power inverter having one or more legs connected between first and second voltage buses is provided. Each leg has respective first and second controllable switches coupled in series to one another. The method allows for applying predetermined respective voltages at the first and second buses. The method further allows for selectively actuating the first and second switches between respective conductive or non-conductive states.

Abstract: A stand-by uninterruptible power supply which provides for extended backup time and/or an increase in power rating for stand-by power supply applications. The uninterruptible power supply also has a waveshape circuit for rating the power capacity of the supply. The waveshape circuit provides a more effective way of rating the capacity of the power supply so that different supplies may be easily compared with little confusion.

Abstract: The controller of power supplying apparatus, upon outputting of a timing signal from a timer, brings a switching element, which is in the conductive state, into the non-conductive state and, in the meantime, brings a switching element, which is in the non-conductive state, into an intermittently conductive state until a NAND circuit stops outputting a short-circuit preventing signal and, thereafter, holds the switching element in the conductive state.

Abstract: An inverter having a large-capacity self-arc-extinguishing semiconductor element. Recovery capacitors recover energy stored in groups of elements for suppressing the rate of change in current, and are provided within a two-level or three-level inverter bridge. The thus-recovered energy is fed back to a d.c. voltage circuit by an energy regenerative circuit. The energy regenerative circuit controls the charging voltage of the recovery capacitors in proportion to the magnitude of a load current. In a case where the inverter includes inverter bridges connected to a single d.c. voltage circuit, the inverter bridges are divided into groups. A different energy regenerative circuit is connected to the inverter bridge on a per-group basis, and each of the energy regenerative circuits feeds power back to the d.c. voltage circuit.

Abstract: A power converter includes first and second voltage busses and a neutral bus. A first switching circuit, e.g., a rectifier circuit, is operative to selectively couple an input node thereof to the first and second voltage busses. A balancer circuit is operative to selectively couple the neutral bus to the first and second voltage busses such that relative magnitudes of respective first and second voltages on the first and second voltage busses are controlled responsive to respective first and second rates at which the balancer circuit couples the first and second voltage busses to the neutral bus. A second switching circuit, e.g., an inverter circuit, is operative to selectively couple the first and second voltage busses to a load connected at an output node thereof.

Abstract: An uninterruptible power supply (UPS) includes an AC source port configured to connect to an AC power source, a DC source port configured to connect to a DC power source and a load port configured to connect to a load. A rectifier circuit is operative to selectively couple the AC source port to first and second voltage busses through a first inductance. An inverter circuit is operative to selectively couple the load port to the first and second voltage busses through a second inductance. A bidirectional DC source coupling circuit is operative to couple the DC source port to the first and second voltage busses to provide bidirectional power transfer therebetween, preferably such that a voltage at the DC source port is maintained in a substantially fixed proportion to first and second DC voltages at respective ones of the first and second voltage busses.

Abstract: A power converter which can provide a power supply grounded on a positive electrode bus of a DC power supply without adding an additional power supply such as a switching regulator and reduce a circuit size and cost is described. When a switching device T1 of an upper arm is ON, the potential at point U is nearly equal to the potential at point P, and the current ic1 flows from the positive electrode of a first drive power supply 21 into a capacitor C1 via a diode D7 to charge the capacitor C1. A power supply Vc formed by the capacitor C1 can be used as a power supply grounded on a positive electrode bus P of the DC power supply.

Abstract: A method and apparatus for protecting a high-performance power converter. The high-performance power converter comprises a mains power converter, which converts an alternating voltage from a mains power supply into a direct voltage and supplies the direct voltage to an intermediate direct voltage circuit. The intermediate direct voltage circuit is equipped with an intermediate circuit capacitor, and includes a second power converter which converts the direct voltage from the intermediate direct voltage circuit into an alternating voltage, whereby each of the mains power converter and the second power converter is set up as a bridge circuit and each contains a number of IGBTs (Insulated Gate Bipolar Transistors) arranged in pairs in bridge arms.

Abstract: A high frequency switching is performed while FETs 21 and 24, and FETs 22 and 23 are alternately switched on according to FET switching signals L and R. For example, a high frequency drive signal F is provided for transistors 31 and 32 through an OR gate 30 while FETs 22 and 23 are in an ON state, thereby alternately turning on and off the transistors 31 and 32 and driving the FET 22 at a high frequency. Similarly, a high frequency drive signal F is provided for two transistors through an OR gate while FETs 21 and 24 are in an ON state, thereby alternately turning on and off the two transistors and driving the FET 24 at a high frequency.

Abstract: For use in a power converter including first and second controllable switches coupled in series across an input, the switches are also coupled to a power transformer, a cross-conduction limiting circuit for, and method of, limiting cross-conduction currents between the first and second controllable switches. In one embodiment, the cross-conduction limiting circuit includes an inductive element, coupled between the first and second controllable switches, that limits a flow of cross-conduction currents between the first and second controllable switches when the first and second controllable switches are simultaneously conducting.

Abstract: A power converter having two main switches connecting an outlet either to a positive rail or to a negative rail, two free-wheel diodes enabling the current through the load to be maintained, two snubber capacitors, and an auxiliary circuit. The auxiliary circuit includes an auxiliary inductor in series with two auxiliary switches coupled between the outlet and a midpoint of a capacitive voltage divider that provides a midpoint voltage. A detector detects current oscillation between the auxiliary inductor and the snubber capacitors, and then switches off the oscillation current and allows the intended main switch to conduct in response to the interruption.

Abstract: A fault tolerant power supply circuit for a series resonant load having an inductive impedance. The power supply circuit includes alternately conducting first and second sets of switches for supplying current to the load in alternating directions. One terminal of the load is connected to a point intermediate the switches. A protective coil is connected in series with the load and the point intermediate said switches. In one embodiment of the invention, a di/dt reactor is connected in series between the switches. In that embodiment, one end of the protective coil is connected to the load and the other end of the protective coil is connected to the di/dt reactor at a point intermediate the switches.

Abstract: This method completely eliminates the detrimental effect of eddy currents on the rise time of the magnetic field, so that it reaches its constant value already when the current assumes its maximum. The field is generated by a current flowing in a coil which forms part of a magnetic system contained in an electromagnetic flow sensor, which comprises a core and/or a pole piece. The current changes periodically its polarity thereby causing the eddy currents. The current flows in a H network of transistors (13, 14, 14, 16) or a T network of switching transistors (25, 26). A resistor (10, 10'; 22, 22') is series connected to the H or T network. In each current half-cycle, an initial voltage during a rise time of the current--as a first subcycle--which is higher than a final voltage during a second subcycle is fed to the coil.

Abstract: A forward converter, having a single switching device, is coupled through an isolation transformer to a crowbar circuit and an output capacitor for controlling the isolated output voltage turn-off. The crowbar circuit, including a trigger device and a resistor, is coupled between the transformer and the output capacitor. The conduction times of the converter switching device are controlled to regulate the energy stored in the transformer and to generate a reverse voltage having a predetermined amplitude. During the output voltage-on mode, the amplitude of the reverse voltage swing is controlled to be sufficiently low such that the converter operates as a conventional forward converter. For output voltage turn-off, the conduction time of the switching device is controlled to obtain a voltage swing of sufficient magnitude to trigger the crowbar circuit, and thus rapidly discharge the output capacitor.

Abstract: A method for processing PWM waves for a voltage inverter or a voltage-controlled rectifier, including at least one pair of switches, said inverter or rectifier being controlled by a modulator and a discriminator. According to the method, two set waves corrected according to the current direction in the load or the source are applied to the discriminator. The corrected set wave for the output current has a high level to which a delay is added during transition from the high level to the low level, and the corrected set wave for the input current has a low level to which a delay is added during transition from the low level to the high level. The high level is defined by the fact that the switch connected to the most positive load is closed while the switch connected to the most negative load is open, and the low level is defined by the reverse.

Abstract: A converter circuit arrangement is specified. An extremely compact structure is achieved by virtue of the fact that the current rise limiting inductor concentrically surrounds the second stack containing diode and resistor. In particular, the inductor can be designed as a wire helix surrounding the stack. A very compact structure of the converter is produced, furthermore, by virtue of the fact that the first and second stacks, that is to say the stack of the switches and the stack of the snubber, belong to a common clamping lattice.

Abstract: A three-level NPC converter includes at least one phase leg including four series coupled electrical switches having a first pair junction between the first two switches and a second pair junction between the second two switches. First and second inner switch snubber capacitors are coupled in series at a neutral junction. First and second inner switch snubber diodes are respectively coupled to the first and second pair junctions and respectively coupled at first and second inner diode-capacitor junctions to the first and second inner switch snubber capacitors. First and second inner switch snubber resistors are respectively coupled between the first and second inner diode-capacitor junctions and respective portions of a DC bus. In one embodiment, the NPC converter further includes first and second outer switch snubber diodes coupled between respective first and second inner diode-capacitor junctions and respective portions of the DC bus.

Abstract: A multilevel cascade voltage source inverter having separate DC sources is described herein. This inverter is applicable to high voltage, high power applications such as flexible AC transmission systems (FACTS) including static VAR generation (SVG), power line conditioning, series compensation, phase shifting and voltage balancing and fuel cell and photovoltaic utility interface systems. The M-level inverter consists of at least one phase wherein each phase has a plurality of full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with only one switching per cycle as the number of levels, M, is increased. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.