Abstract: A semiconductor module includes: a first terminal portion and a second terminal portion each connected to outside; and a first current path and a second current path to connect between the first terminal portion and the second terminal portion in parallel. The first current path includes: a first semiconductor device; a first wiring portion and a second wiring portion. The second current path includes: a second semiconductor device; a third wiring portion; and a fourth wiring portion. A power conducting capability of the first semiconductor device is lower than a power conducting capability of the second semiconductor device, and a total of an impedance of the first wiring portion and an impedance of the second wiring portion is lower than a total of an impedance of the third wiring portion and an impedance of the fourth wiring portion.

Abstract: An electromagnetic generation circuit that works with a dedicated load in a closed circuit to generate electromagnetic fields responding to one half of a normal alternating current sine wave on an inductor. The circuit makes it possible to generate electromagnetic fields away from or externally from the dedicated load while maintaining sine wave integrity.

Abstract: A method of providing an input switching request signal to an input side switch includes determining a switching request window indicative of relaxation ringing during a first switching cycle. It is determined that the input side switch is operating in a discontinuous conduction mode (DCM) mode of operation during a second switching cycle. It is determined that the switching request window is open during the second switching cycle. The input switching request signal is enabled in response to determining the switching request window is open.

Abstract: An efficient high voltage power supply suitable for capacitor discharge applications is provided by eliminating the need for complex timing controls and the addition of parts required for capacitor discharge applications. The use of three steps in the inverter section, a charge, discharge and revert steps, generally eliminates the complex timing requirements typically associated with high voltage power supplies while still achieving high efficiency. The addition of a high voltage relay, resistor, and appropriately specified diodes in the rectifier section makes the power supply more applicable for use in capacitor discharge applications than existing commercial off-the-shelf high voltage power supplies.

Abstract: A DC to AC converter is described in which DC power presented as a set of relatively floating DC power sources of differing DC voltage values is converted to a desired AC power waveform by combining the DC voltage values with sequential sets of associated ternary-valued multiplicative weights of +1, ?1, or 0, and summing the weighted voltage values, so as to produce voltage points on the desired waveform at appropriate time instants.

Abstract: A power converter is basically provided with at least three switching circuits, at least one power source, at least one load, and a resonant circuit. Input terminals of the switching circuits are connected to either the at least one power source or the at least one load, and output terminals of the switching circuits are electrically serially connected to the resonant circuit to form a closed circuit.

Abstract: A method and circuit arrangement is described for start-up and shut-down of high power DC to AC inverters which limits inrush current for capacitor charging, reduces input and output relay contact stress and discharges internal capacitors upon shut down. A preferred inrush limiting component has a higher resistance when hot than when cold, such as an incandescent filament lamp.

Abstract: Transformerless bimodal inverters provide grid-tie outputs for back-feeding solar-originated power from a battery to a utility power grid in a grid-tied mode, simultaneously or alternatively with providing a constant-voltage AC output for powering AC appliances or loads directly in a standalone mode. The inverters continue to operate in the standalone mode without interruption should the grid-tied mode cease, e.g., due to anti-islanding during a grid outage or other fault condition not affecting the standalone mode. Conversely, the inverters continue to operate in the grid-tied mode should the standalone mode trip out, e.g., due to a current overload or other condition not affecting the grid-tied mode.

Abstract: A method for use in reducing an inductance of a circuit including a commutation loop defined at least in part by a source conductor and a return conductor between a first component and a second component is described. The method includes disposing a conductive inductance reducer within the commutation loop. The conductive inductance reducer includes an electrically conductive material and an insulator.

Abstract: A static Voltage Ampere Voltage Reactive (VAR) comparator including: a plurality of capacitors being in a Y-connected structure and supplying three-phase alternating current power according to a switching operation; a plurality of bidirectional thyristors connected to the plurality of capacitors in serial to open and close the plurality of capacitors; and a controller, in response to power applied to the static VAR compensator, periodically applying a firing pulse signal to the plurality of bidirectional thyristors reaching to a voltage phase on which a transient current is minimized, wherein, at a point in time when first applying the firing pulse signal to one bidirectional thyristor, the controller applies simultaneously applies the firing pulse signal to the one bidirectional thyristor and other remaining bidirectional thyristors allowing a current to flow on three phases.

Abstract: A resonant inverter includes an input terminal, a first switch, a second switch, a transformer, a first resonant circuit, and a second resonant circuit. To the input terminal, an input voltage is applied. The first switch and the second switch are alternately turned on and off. The transformer includes a first winding and a second winding on a primary side. The first resonant circuit includes a first capacitive element and a first coil. The second resonant circuit includes a second capacitive element and a second coil. The first switch, the first winding, and the first resonant circuit constitute a first inverter circuit. The second switch, the second winding, and the second resonant circuit constitute a second inverter circuit. The input terminal is connected between the first winding and the second winding.

Abstract: A resonant power converter is provided. The resonant power converter comprises a balancing circuit for balancing the voltage in a feeding connection. The balancing circuit comprises: a first positive control means in series with an inductor, wherein the first positive control means and the inductor is coupled between the positive DC conductor and the feeding connection, and a second negative control means in series with the inductor, wherein the second negative control means are coupled between the negative DC conductor and the feeding connection. The first positive and second negative control means are adapted to be alternatingly switched on and off for balancing the resonant power converter, such that the voltage in the feeding connection is substantially the mean voltage of the positive DC conductor and the negative DC conductor.

Abstract: A power converter is presented. The power converter includes at least one leg operatively coupled between a first bus and a second bus and includes a first string including a plurality of non-controllable semiconductor switches, a first node, a second node, and a third node, where the first node is coupled to a third bus, one or more second strings, where each of the one or more second strings includes at least one fully controllable semiconductor switch, and where one of the second strings is coupled between the first node and the third bus and another second string is coupled between the second node and the third node, and one or more third strings, where each of the one or more third strings includes at least one energy storage device and is coupled to the first string, the one or more second strings, or a combination thereof.

Abstract: A multilevel power converter circuit driven by two direct current power supplies in series includes a first semiconductor switch series circuit that combines a series circuit of 2n IGBTs connected between positive and negative electrodes with a capacitor, a second semiconductor switch series circuit that combines a series circuit of 2n?2 IGBTs connected between the emitter of a first IGBT of the first semiconductor switch series circuit and the collector of a 2nth IGBT with a capacitor, and a bidirectional switch connected between an intermediate point of the second semiconductor switch series circuit and an intermediate point of the direct current power supply, to reduce a voltage change in the alternating current output when semiconductor switches are switching.

Abstract: This system for converting a direct input voltage into an alternating output voltage comprises two input terminals, two voltage generators connected in series between the input terminals and connected to one another by a middle point, as well as, for each phase of the alternating voltage, an output terminal, two switching branches each connected between the output terminal and a respective input terminal, each switching branch comprising N first switching cells connected in series and N?1 intermediate points, the first switching cells successively being connected to one another by a corresponding intermediate point, N being an integer greater than or equal to 2, and control means for controlling the first switching cells. The system includes, for each phase of the alternating voltage, N?1 pair(s) of capacitors, each pair of capacitors being connected between intermediate points of one of the two switching branches and the other of the two switching branches.

Abstract: An electrical circuit for a power converter is described. The circuit has been provided with several semiconductor switches and capacitors used for operating the power converter. A brake resistance for lowering energy is provided and is connected to the semiconductor switches provided without the need for an additional switch. The operation of the power converter and the current flowing through the brake resistance can be controlled by means of the existing semiconductor switches.

Abstract: An object of the invention is to accurately detect a state of an object to be heated in a cooking vessel and effectively avoid cooking failure. An induction heating section (13) inductively heats a cooking vessel (11). A vibration detecting section (14) detects a vibration of the cooking vessel (11) via a top plate (12). A vibration waveform extracting section (15) extracts a vibration waveform of a frequency component having a frequency equal to a predetermined multiplication product of an induction heating frequency, from a waveform of the vibration detected by the vibration detecting section (14). A determining section (16) determines a state of an object to be heated, based on the vibration waveform extracted by the vibration waveform extracting section (15).

Abstract: In a power inverter, a coolant passage is fixed to a chassis to cool the chassis; the chassis is divided into a first region and a second region by providing the coolant passage in the chassis; a power module is provided in the first region as fixed to the coolant passage; a capacitor module is provided in the second region; and the DC terminal of the capacitor module is directly connected to the DC terminal of the power module.

Abstract: A power converter is presented. The power converter includes at least one leg, the at least one leg includes a first string, where the first string includes a plurality of controllable semiconductor switches, a first connecting node, and a second connecting node, and where the first string is operatively coupled across a first bus and a second bus. Furthermore, the at least one leg includes a second string operatively coupled to the first string via the first connecting node and the second connecting node, where the second string includes a plurality of switching units. A method for power conversion is also presented.

Abstract: A power isolation system and method is disclosed. The system includes a transformer suitable for use in the power isolation system, and a semiconductor device electrically connected to the transformer to provide a reduction of the inrush current associated with powering the transformer, wherein the semiconductor device is activated upon power up based upon the previous shutdown state of the power isolation system to provide a soft start to the transformer, and after activation of the transformer, the semiconductor device is shorted in the system.

Abstract: A control system and method for a multi-phase motor substantially reduces or eliminates jitter resulting from. drive mismatch by replacing a conventional trapezoidal drive profile with a drive profile that causes the voltage applied across active phases of the motor to match the back-EMF across those phases. In an ideal motor, the back-EMF is substantially sinusoidal, and although the drive profile applied to each phase is not truly substantially sinusoidal, the drive voltage across the active phases is substantially sinusoidal. In a non-ideal motor, the back-EMF is not truly sinusoidal and the drive profiles applied to each phase are calculated to cause the drive voltage across the active phases to match the back-EMF across those phases.

Abstract: The present invention relates to a circuit arrangement which comprises at least one 3-level pulse width modulation inverter with a snubber circuit. The snubber circuit is formed by at least one coil (L), two capacitors (Cu, Co) and a series connection comprising four diodes (Dh1-Dh4) poled in the same direction, whereof the two outer diodes (Dh1, Dh4) are in each case directly connected to the input terminals (1, 3) for the positive and the negative pole of the input voltage. The electrical connection between the two inner diodes (Dh2, Dh3) is connected on the one hand via the coil (L) to the input terminal (2) for the center tap of the input voltage and on the other hand to the middle bridge branch of the pulse width modulation inverter. In one embodiment, the two capacitors (Cu, Co) are in each case connected with one terminal to the electrical connection between one of the inner diodes (Dh2, Dh3) and one of the outer diodes (Dh1, Dh4) and with the other terminal directly to the output terminal (4).

Abstract: Systems, methods and computer program products for reducing or removing current spikes generated during a current recirculation period associated with phase switching in a spindle motor are described. In some implementations, the duty cycle of the drive signals applied to the windings of the spindle motor can be adjusted to reduce or eliminate the current surge resulting from current recirculation. In some implementations, the duty cycle of the drive signals during spin-up can be reduced based on a current limit, and the reduced duty cycle can then be used to drive the spindle motor taking into account of current surges in the supply current.

Abstract: A power conversion apparatus includes an inverter for converting DC power to AC power for supply to a load, a converter for converting AC power from an AC power supply to DC power for supply to the inverter, and a DC voltage converter for converting a voltage value of power stored in a storage battery and supplying DC power from the storage battery to the inverter when power supply by the AC power supply is abnormal. The converter includes a first three-level circuit which is a multi-level circuit. Similarly, the DC voltage converter includes a second three-level circuit. A control device controls the first and second multi-level circuits to suppress potential fluctuation at a neutral point between first and second capacitors.

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: A control system and method for a multi-phase motor substantially reduces or eliminates jitter resulting from drive mismatch by replacing a conventional trapezoidal drive profile with a drive profile that causes the voltage applied across active phases of the motor to match the back-EMF across those phases. In an ideal motor, the back-EMF is substantially sinusoidal, and although the drive profile applied to each phase is not truly substantially sinusoidal, the drive voltage across the active phases is substantially sinusoidal. In a non-ideal motor, the back-EMF is not truly sinusoidal and the drive profiles applied to each phase are calculated to cause the drive voltage across the active phases to match the back-EMF across those phases.

Abstract: A universal power supply for use in a plasma arc system is disclosed. The power supply can include a plurality of power modules for providing a DC output from an AC input. Each of the power modules can include a rectifier, a converter, an inverter, an isolation transformer and an output rectifier. The power modules can include a power module controller configured to control at least one of the rectifier, the converter, or the inverter such that a DC output can be obtained from a wide variety of AC inputs. The power modules can be connected in parallel to provide a wide range of DC output currents for the power supply. The universal power supply can include a master controller coupled to each of the individual power module controllers to regulate the DC output current of the power supply by controlling the individual power module controllers.

Abstract: In general, in one aspect, the invention relates to a method for delivering a controlled voltage. The method involves, during a first electric pulse delivered to a primary transformer, holding a first switching section open to isolate the controlled voltage, where the first electric pulse creates a first magnetic flux in a core of the primary transformer, and where the first magnetic flux generates a direct current (DC) magnetizing current. The method further involves receiving the controlled voltage from a voltage source using the DC magnetizing current at a first switching section, and upon termination of the first electric pulse, closing the first switching section to deliver the controlled voltage to the primary transformer.

Abstract: A DC motor is provided. The DC motor prevents rush or overload of current in the DC motor during and/or after power input irregularities to the DC motor. A control circuit of the DC motor is configured to control current provided to the DC motor. When power irregularities in the power input to the DC motor are detected by the control circuit, the control circuit stops generating PWM (Pulse Width Modulated) signals and stops the current provided to the DC motor. After the stoppage of PWM signals, the control circuit can perform a soft-start of the PWM signals when the power irregularities are no longer detected. The soft starting of the PWM signals generates gradual increase in current to the DC motor, thus, preventing sudden rush of current that cause malfunction of the DC motor.

Abstract: The present invention relates to a motor controller of an air conditioner, including a converter for converting a commercial AC power into a DC power, an inverter including a plurality of switching elements, the inverter receiving the DC power, converting the DC power into an AC power through a switching operation and driving a three-phase motor, a gate driver for controlling the switching operation of the switching elements, and a plurality of voltage drop units connected between the converter and the gate driver, the voltage drop units dropping the DC power and supplying driving voltages for an operation of the switching elements. Accordingly, circuit elements within a controller can be protected.

Abstract: A power supply control device for lamp includes a control unit, the control unit receives a forward voltage signal and a reverse voltage signal simultaneously from a zero-crossover sampling circuit and determines if a connected load is an LED lamp, then the control unit turns on a tri-electrode AC switch (TRIAC) after an operating voltage for the LED voltage is reached, thereby outputting the AC power to an outlet for illuminating the LED lamp; since the TRIAC can be turned on with the forward voltage or the reverse voltage, the LED lamp is powered with a stable power supply to prevent the LED lamp from blinking.

Abstract: A drive system for a multi-phase electric machine with a permanent magnet rotor, the drive system may comprise conduction paths for each phase. Detectors on each of the conduction paths may determine electrical condition of the conduction path. At least one selectable interconnection path may be present between all of the conduction paths and at least one selectable interconnection path may be operable to connect all of the conduction paths together responsively to at least one of the detectors determining that the electrical condition of its respective electrical path is representative of a predetermined electrical fault condition so that heating of the rotor during continued rotation of the rotor is prevented.

Abstract: Optimal operating techniques are disclosed for using coreless printed-circuit-board (PCB) transformers under (1) minimum input power conditions and (2) maximum energy efficiency conditions. The coreless PCB transformers should be operated at or near the ‘maximum impedance frequency’ (MIF) in order to reduce input power requirement. For maximum energy efficiency, the transformers should be at or near the “maximum efficiency frequency” (MEF) which is below the MIF. The operating principle has been confirmed by measurement and simulation. The proposed operating techniques can be applied to coreless PCB transformers in many circuits that have to meet stringent height requirements, for example to isolate the gates of power MOSFET and IGBT devices from the input power supply.

Abstract: A photovoltaic system may include a DC to AC inverter including a minimum operating power setting and a microprocessor for calculating a maximum available power output for a photovoltaic array.

Abstract: In general, in one aspect, the invention relates to a method for delivering a controlled voltage. The method involves, during a first electric pulse delivered to a primary transformer, holding a first switching section open to isolate the controlled voltage, where the first electric pulse creates a first magnetic flux in a core of the primary transformer, and where the first magnetic flux generates a direct current (DC) magnetizing current. The method further involves receiving the controlled voltage from a voltage source using the DC magnetizing current at a first switching section, and upon termination of the first electric pulse, closing the first switching section to deliver the controlled voltage to the primary transformer.

Abstract: The present invention discloses a power converter with low standby power consumption, used to convert an AC input power to an output DC power, comprising: an EMI filter, coupled to the AC input power to filter the EMI; a TRIAC, coupled to the EMI filter to access the AC input power; and a TRIAC driver, used for driving the gate of the TRIAC switch according to an on-off control signal from a loading device, to control the conduction of the TRIAC switch.

Abstract: A method and a circuit for controlling a thyristor (V1) into conducting state, the thyristor (V1) being in a rectifier, which rectifier supplies DC voltage to a DC voltage circuit. The circuit comprising a trigger capacitor (C2) adapted to be charged from the voltage difference across the thyristor (V1) when the anode-to-cathode voltage of the thyristor is positive, a zener diode (V5) adapted to be triggered with the voltage of the trigger capacitor (C2), when the voltage of the trigger capacitor (C2) exceeds the breakdown voltage of the zener diode (V5), and an auxiliary thyristor (V3) adapted to be triggered with the current from the trigger capacitor (C2) flowing via the zener diode (V5), wherein the cathode of the auxiliary thyristor (V3) is connected to the gate of the thyristor (V1) for triggering the thyristor (V1) with the current from the trigger capacitor (C2) flowing via the auxiliary thyristor (V3) for using the thyristor (V1) in a diode mode.

Abstract: In a method for measuring motor speed and position by detecting the back-EMF generated during pole-pair interactions, fluctuations of a three-phase motor power supply that may affect back-EMF detection are reduced. One phase of the power supply is tristated for a certain interval preceding and during back-EMF detection. For a shorter interval during back-EMF detection, the voltage drop across the motor is reduced from the full power supply voltage. This preferably is accomplished either by pulling a first of the other two power supply phases low, while pulling a second of the other two power supply phases up to a regulated voltage below the power supply voltage, or by pulling the second of the other two phases up to the power supply voltage and pulling the first of the other two phases down to a regulated voltage above ground.

Abstract: A pulse power source comprises a first circuit, a second circuit, a transformer for coupling the first circuit and the second circuit, and a switching controller. The second circuit comprises a third semiconductor switch connected in series with a secondary winding of the transformer. The third semiconductor switch is connected in such a direction that a voltage generated in the second circuit is reverse-biased during a period in which the second semiconductor switch is turned on. A gate amplifier for forming a control signal from the switching controller into a pulse and outputting the pulse as a pulse signal is connected between a gate terminal and a cathode terminal of the third semiconductor switch.

Abstract: A power semiconductor device having a low loss and a high reliability and a power conversion device using the power semiconductor device are provided. In the power semiconductor device, a plurality of MOS type trench gates are positioned to be spaced by at-least two types of intervals therebetween, a low-resistance floating n+ layer is positioned on a main surface of a semiconductor substrate adjacent to a floating p layer positioned between the adjacent MOS type trench gates having the broad interval to achieve consistency between a low output value and a high breakdown resistance.

Abstract: A method for triggering a high voltage solid state switch comprised of a set of thyristors connected in series. Initiating switch turn-on requires command triggering of only the lowest voltage thyristor, thereby eliminating the need for expensive high voltage pulse transformers or optically isolated triggers. Triggering of one thyristor causes a redistribution of voltage across the switch, generating a current flowing through the snubber circuit across each untriggered thyristor. This current is coupled to the gate of each thyristor causing all of them to turn on simultaneously. This results in an inexpensive method for triggering a high voltage solid state switch.

Abstract: The invention discloses a method, together with circuits for performing these actions, of driving a capacitance with a quasi-square wave of variable duty cycle and frequency in such a manner that the energy stored in the capacitor is not lost. The energy is actually recycled to be stored back in the capacitor again but with an effective opposite polarity voltage. The circuits to achieve this operation comprise of the capacitor to be driven, coupled to an inductor which is driven by either two switches and two diodes, or by two bilateral switches and timing circuitry.

Abstract: The invention in the simplest form is a power conditioning and inverting system for improved and efficient power generation. In particular, the present invention is a modulated dc link scheme that dramatically reduces the switching frequency ripple across the PWM output filter inductor and provides cost, size, and weight reductions, as well as efficiency enhancements. In a preferred embodiment of the present invention, the DC-DC converter control takes a feedback signal proportional to the inverter output voltage. This feedback is “summed” into the primary DC-DC volts command thereby causing the dc bus/link voltage to vary at a multiple of the output fundamental frequency causing the DC link to become a signal at a fundamental frequency voltage with a dc offset. The tooth modulator DC supply tracks the AC output voltage, reducing the difference between the applied DC volts and the AC output volts, thereby reducing inductor core losses.

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: Thyristor-controlled series capacitor equipment (CEQ), intended for connection between an ac network (NET) and a converter (CONV), connected thereto, for conversion between alternating current ((IT) and high-voltage direct current (Id), with a controllable semiconductor valve (TYSW), has control equipment with control means (32) which, in dependence on a synchronization signal (&PHgr;SYNC), form firing pulses (TP1,TP2) for control of the semiconductor valve. The converter has a control device (CTR1) which forms a control-angle order (&agr;-ORD) for phase-angle control of the converter, related to the phase position for a voltage (U12) at a chosen connection point (J2).

Abstract: An ARCP converter having a series circuit formed of at least four main switches per converter phase, which are connected electrically in parallel between DC voltage rails is described. A capacitance is connected in parallel with each individual main switch. Two intermediate-circuit capacitances are disposed between the DC voltage rails. A voltage neutral point of the capacitances is available for tapping. Junction points of adjacent main switches which do not form the output are connected to one another via variable-potential intermediate-circuit capacitances for forming commutation cells in a balanced manner with regard to the DC voltage rails. Each intermediate-circuit capacitance is formed of two capacitance elements, whose junction points are available as voltage neutral points, with the output of the converter phase connected to a resonant inductance, whose further connection is connected to all the voltage neutral points via a controllable bi-directional auxiliary switch.

Abstract: Reflux diode 5u.about.5w and 5x.about.5z are in anti-parallel connected to MOSFET 4u.about.4w and 4x.about.4z. When MOSFET 4u.about.4w and 4x.about.4z are turned OFF, an electric current flows in a forward direction to reflux diode 5u.about.5w and 5x.about.5z. In the case of this construction, when for example reflux diode 5u disconnects, a small inverse voltage is applied from inverse voltage applied circuit 7 to reflux diode 5u. For this reason, as the inverse recovery of reflux diode 5u is produced by low voltage direct current power source 8 of inverse voltage applied circuit 7, loss occurring at reflux diode 5u is reduced.

Abstract: A converter circuit arrangement is specified having a rectifier, an intermediate circuit and an invertor connected thereto. In order to protect the circuit against failures and overvoltage, a protection circuit which comprises, in particular, varistors is connected between the two partial rectifiers of the rectifier.

Abstract: A resonant DC link converter which is specifically adapted for driving a switched reluctance motor (SRM) using low power (VA) rated switches, includes an input circuit providing a DC supply voltage, a resonating inductance (connected to the switched input circuit) for generating a resonating DC link current, and an output converter circuit synthesizing a multi-phase AC output signal to power a respective phase winding of the SRM. A controller switches the switch devices of the input circuit and output converter circuits in a predetermined sequence.

Abstract: A high power inverter pole for a voltage sourced inverter suitable for providing compensation in electric power transmission and distribution systems, has a positive switching valve and a negative switching valve connected between closely spaced dc-source terminal, respectively, and a common ac terminal to form a current loop with minimum loop area thereby reducing stray loop inductance and limiting the overshoot voltage on serially connected electronic switches which make up the valves. In a preferred embodiment, the valves are mounted on opposite sides of the web of an insulative I-beam. The electronic switches are incorporated in modular switching units connected in series by C-channel connecting conductors having flanges bolted to the I-beam flanges. The modular units include broad, flat conductors bolted through end flanges to the C-channel connecting conductors. The electronic switches and anti-parallel diodes of the modular units are clamped between these broad, flat conductors.