Abstract: A computer system uses a power distribution network arranged to propagate at least one voltage potential to an integrated circuit. A resonance detector is arranged to detect a power supply resonance. A damping circuit is operatively connected to the resonance detector and the power distribution network. The damping circuit resides external to the integrated circuit and dampens the power supply resonance under control of the resonance detector.

Abstract: An active EMI filter for reducing common mode noise current in a circuits, comprising: a transistor stage having two transistors coupled in series, a current sensor for sensing the common mode noise current, the current sensor having an output driving the transistor stage, whereby each of the transistors is driven in response to the common mode noise current, a capacitor coupling the transistor stage and the ground return line, the capacitor providing a cancellation current to cancel the common mode noise current, the current sensor comprising a current transformer having a primary coupled with the circuit having the common mode noise. The current sensor and the transistor stage may be coupled in a feed forward arrangement wherein the transistor stage and the current sensor have an amplitude gain of approximately unity; or in a feedback arrangement wherein the transistor stage and current sensor provide high gain.

Abstract: An active EMI filter for reducing common mode current in a circuit comprising a rectifier coupled to an AC network, the rectifier supplying DC power to a DC bus, the DC bus feeding an inverter stage for providing AC power to a load, the load having a ground return line to a ground connection of the AC network, the active filter comprising: a transistor switching stage coupled across the DC bus, a current sensor coupled to the DC bus for sensing the common mode current flowing in the DC bus and proportional to the common mode current flowing in the ground return line from or to the load, the current sensor having inputs coupled to respective legs of the DC bus and an output driving the transistor switching stage, the transistor switching stage comprising two transistors driven by said output of the current sensor whereby one of said transistors is turned on by said current sensor output depending on the direction of common mode current in said DC bus, a capacitor coupling said transistor switching stage and sa

Abstract: An ac-to-ac power converter includes a source-side inverter that is operated in current mode and a drive side inverter that is operated in commutation mode. The source side inverter performs current regulation during a first portion of each modulating cycle and space vector modulation during a second portion of each modulating cycle.

Abstract: Techniques for reducing noise generated by a circuit include a common mode filter and a differential mode filter. The common mode filter includes an input for sensing a common mode signal between a power source and the circuit, an output, and active circuitry for producing an offset signal on the output. The differential mode filter includes an input, an output, and active circuitry for sensing a differential mode signal and producing variations in resistance between the input and output to offset the differential signal.

Abstract: The present invention provides a switching power supply which has an overcurrent protection characteristic with a small number of components. The switching power supply includes a regulator from a drain and an auxiliary winding VCC, a drain current detection circuit for detecting a current applied to a switching element, an oscillation circuit for outputting a clock signal of a constant frequency, a feedback signal control circuit for detecting a control signal from the secondary side and controlling current applied to the switching element, a clamping circuit for controlling the maximum value of current applied to the switching element, and a clamp voltage variable circuit for changing a clamp voltage of the clamping circuit and an oscillation frequency of the oscillation circuit according to a voltage of VCC.

Abstract: An active EMI filter senses current in a ground line as a voltage across a capacitor coupled to the ground line. The EMI filter senses common mode voltage and determines a difference between the common mode voltage and noise to provide an output to the ground line to reduce the difference.

Abstract: A common mode noise cancellation circuit eliminates common mode noise generated by one or more high-frequency switching devices. A common mode noise waveform generated by the one or ore switching devices is capacitively coupled from the primary winding to the first secondary winding of a transformer. A set of cancellation secondary windings generates a common mode cancellation waveform, and cancels the common mode noise waveform because the common mode cancellation waveform is approximately equal in amplitude and opposite in phase to the common mode noise waveform. A triac control circuit receives an AC input and determines whether the AC input is within a range where multiplying of the DC voltage is implemented. If the triac control circuit determines the AC input is within the range, the triac control circuit transmits a triac firing signal to the triac circuit. The triac circuit charges a capacitor bank to multiply the DC voltage.

Abstract: A power converter outputting a large current while reducing harmonics flowing into an AC power supply and an AC load. The power converter includes power units, each of which includes an input transformer having at least one primary winding connected with a polyphase AC power supply and at least one secondary winding, a polyphase self-excited rectifier circuit connected with the secondary winding, and a single-phase self-excited inverter circuit connected with the polyphase self-excited rectifier circuit through a DC link circuit to generate a single-phase output. One of single-phase outputs of each power unit is connected with one of single-phase outputs of another power unit so that the outputs of the power units are cascaded in series with one another, with serially connected outputs of the power units connected to a polyphase AC load.

Abstract: A motor drive including an input for alternating current, a rectifier circuit, an inverter, an output which provides the controlled alternating current to drive a motor; and an active EMI filter for eliminating common mode noise in the motor drive which employs a magneto-resistive sensor. In the filter, a pair of lead frame bars which are connectable to the current path of the motor drive and an MR sensor in the form of a Wheatstone bridge are fabricated on a semiconductor die, with the bridge in contact with and straddling the lead frame bars. The bridge elements are so oriented that opposed elements in the bridge are responsive to changes in magnetic flux in a first sense to exhibit an increase in resistance, and adjacent elements in the bridge are responsive to changes in magnetic flux in a second sense opposite to the first sense to exhibit an increase in resistance.

Abstract: An RMS-to-DC converter system is disclosed. The system includes a variable gain amplifier having transfer function ripple that receives an input signal and provides an amplifier output signal, a detector that receives the amplifier output signal and provides a detector output signal, an error amplifier that receives the detector output signal and provides an error amplifier output signal having an AC component, and a feedback circuit coupled to the error amplifier output signal and to the variable gain amplifier for providing a feedback signal to the variable gain amplifier that includes an AC component for reducing transfer function ripple of the RMS-to-DC converter system.

Abstract: The invention is an electrical power conversion apparatus for converting DC voltage to poly-phase AC current where the AC current is supplied directly to the electric utility grid for power transfer into the grid. The power conversion apparatus has two or more separate, pulse modulated, high frequency power converters per phase. The outputs of the power converters are summed at a common connection point substantially on the load side of the main pulse filter inductors. The high frequency pulse train of each separate power converter is skewed or phase delayed with respect to the other converters on the same AC power phase for the purpose of reducing the amount of high frequency ripple current injected into the electric utility grid.

Abstract: A power supply electromagnetic interference (EMI) filter circuit and technique. In one embodiment, a method of filtering EMI in a power supply includes rectifying an AC signal from an AC source, smoothing the rectified AC signal with a bulk storage capacitor to provide a DC output as an input to a power conversion circuit and filtering the EMI generated by the power conversion circuit from reaching the AC source by using the bulk capacitor and one or more inductors in combination with the AC source capacitance as an EMI filter. In one embodiment the method also includes the use of one or more of the inductors as a fusing element.

Abstract: A DC mitigation circuit for mitigating the effects of DC in power systems, and a method for doing the same, are provided. The DC mitigation circuit comprises a control circuit for evaluating the amount of DC or harmonic currents resulting from the DC in a transmission line. Switches provide a current to a winding of a transformer, and are controlled by the control circuit. The current provided to the winding generates a magnetic flux that offsets a flux created by DC or harmonic currents resulting from the DC induced by geomagnetically-caused ground-induced currents in the transmission line.

Abstract: A half-bridge converter having an improved power factor is provided. The half-bridge converter has a bridge diode unit for providing a current path to a power factor improving unit and transmitting energy to a voltage smoothing capacitor; the voltage smoothing capacitor for storing energy provided by the bridge diode unit; and a switching unit having two switches serially connected between both ends of the voltage smoothing capacitor, in which the power factor improving unit for feeding the voltage of the common connection point of the switches forming the switching unit back to the common connection point of the input capacitors so as to change an input current according to the magnitude of the input voltage is further included. According to the half-bridge converter, conducting loss occurring in the switching unit decreases and the power factor of the input terminal is improved.

Abstract: A harmonic wave distortion suppressor includes a main body, at least a connecting pin and a coating. The main body is made of a first material and covered with a second material for absorbing an instantaneous high voltage or sharp wave. The connecting pin is coupled to two lateral sides of the main body respectively so as to form a capacitor. The coating is coated on the main body locally with a clearance being exposed and the clearance provides a function of charging and discharging locally. When the high voltage or sharp wave passes through the harmonic wave distortion suppressor, peak discharging effect of the clearance can not only isolate the high voltage or sharp wave from entering an electronic device but also prevent an iron core in the electronic device from occurring magnetization effect resulting from the high voltage or sharp wave so that quality of signal transmission and receiving can be secured.

Abstract: A computer system uses a power distribution network arranged to propagate at least one voltage potential to an integrated circuit. A resonance detector is arranged to detect a power supply resonance. A damping circuit is operatively connected to the resonance detector and the power distribution network. The damping circuit resides external to the integrated circuit and dampens the power supply resonance under control of the resonance detector.

Abstract: An active EMI filter senses current in a ground line or a power transmission line as a voltage cross a capacitor coupled to the line. The EMI filter senses common mode voltage and determines a difference between the common mode voltage and noise to provide an output to drive the difference to zero. The resulting active closed loop EMI filter produces good EMI dampening with greatly increased performance over a current transformer type EMI filter. A voltage regulator for the error amplifier improves noise reduction while increasing filter efficiency. The active EMI filter operates in a wide linear range that is greater than that of an equivalent current transformer circuit, while providing low cost and reliability.

Abstract: In a DC converter, a transformer has a first winding coupled in series with a first capacitor and a first switch between a first pair of terminals, and a second winding coupled in series with a second capacitor and an inductor between a second pair of terminals. A second switch is coupled in parallel with the series-connected first winding and first capacitor. A third switch or diode is coupled in parallel with the series-connected second winding and second capacitor. The capacitors provide energy transfer in either direction via the transformer. Leakage inductance of the transformer facilitates zero voltage switching conditions, and the transformer core is reset in each cycle by charge balancing between the capacitors. The switches can comprise AC switches. The transformer can be an autotransformer.

Abstract: A motor control apparatus includes a fundamental wave current control system that controls a fundamental wave component of a motor current in an orthogonal coordinate system and a higher harmonic current control system that controls a higher harmonic component contained in the motor current in an orthogonal coordinate system. In the motor control apparatus, it is judged whether an output voltage from the power conversion device is in a saturated state, and a current control gain for the higher harmonic current control system is reduced if it is judged that the output voltage is in the saturated state.

Abstract: A new method in the design for an electronic power supply for suppressing signal interference in equipment of an electronic system due to ground current in a ground loop is provided. In a power supply comprising a transformer, a primary circuit, a secondary circuit, and ground conductors, the method is done by connecting the common signal references of secondary side to the ground conductors through a capacitor and an inductor connected in series. The added capacitor is to reject DC and low frequency noise and interference, and the added inductor is to reject high frequency noise and interference. Most noise and interference signals therefore cannot pass through the formed paths. As a result, the degree of signal interference problem is greatly reduced.

Abstract: A parallel resonant circuit for removing noise and harmonic frequencies from the AC power source is connected directly in parallel to a power source with no intervening electrical components. The parallel resonant circuit is comprised of at least one inductor for drawing an inductive current that is substantially equal to but one hundred and eight degrees out of phase with at least one capacitor that draws a capacitive current. The capacitors and the inductors of the parallel resonant circuit are connected in parallel and may be tuned to the fundamental frequency of the power line.

Abstract: A method and apparatus for suppressing noise caused by the switching of a switching power supply. The method and apparatus use frequency dithering techniques to distribute the switching noise and its spurious products over a wider bandwidth, thereby reducing the average peak power per given range of bandwidth. The frequency dithering techniques are particularly applicable to mobile radio applications, where switching noise from switching power supplies can modulate the transmit carrier and its harmonics, sub-harmonics and intermediate frequency products.

Abstract: The invention relates to a compensation circuit for the phase shift between a first input (3) for a voltage determination and a second input (4) for a current determination in electric meters for direct connection, whereby a DC-tolerant converter (5), for current transformation, is arranged before said second input (4) and a high pass filter (R1, C) is arranged before the first input (3), for a first equalisation of the non-frequency-dependant phase compensation. A further equalisation of the phase compensation occurs by means of a correction device (5) in a measuring chip (2), which is connected in series with the inputs (3, 4) for voltage determination and current determination.

Abstract: A phase converter that converts single phase AC electric power to balanced three phase AC power. Two input terminals are connectable to a single phase AC power source, and connect directly to two output terminals of the converter. The phase converter has a storage capacitor, a charging circuit for controlled charging the storage capacitor and an output circuit for controlled discharge of the storage capacitor to provide single phase AC power to a third output terminal. The charging circuit controls input to the storage capacitor to provide a sinusoidal input current and to step up the voltage to the storage capacitor. The output circuit provides output power to the third output terminal of a predetermined phase and amplitude, relative to the other two output terminals, to result in balanced three phase AC power at the three output terminals.

Abstract: A frequency regulator protection circuit for controlling acceleration of electric vehicle comprises a power unit, a display unit, a protection unit, a control unit, a sensor unit, a data processor unit, a trigger unit, a regulator unit, and an output unit. The control unit receives a rotation speed signal from a motor. The sensor unit detects whether there is a current overload and delivers a corresponding overload signal to the data processor unit that consequently outputs a frequency change signal to the trigger unit which, in turn, delivers a first regulation signal to the regulator unit. The output unit further delivers a second regulation signal to the regulator unit, corresponding to different situations of insufficiency of pedal control, brake control, over-speed control, or motor overload. The regulator unit consequently effectuates an adequate cutoff of power supply.

Abstract: A controller for a pulse width modulated electrical drive or a dual-mode, pulse width modulated/variable voltage inverter drive is coupled to sensors within a filter at the drive output. Upon detecting failure of the filter or filter components (e.g., a capacitor short or blown fuse) through the sensors, the controller either shuts down the drive or automatically switches the drive operating mode to an output mode which does not require filtering. Damage to the electrical system or downhole equipment from transmission of unfiltered or improperly filtered power may thus be averted upon failure of the filter or a filter component.

Abstract: An apparatus and method for controlling voltage applied to an electrostatic precipitator is disclosed. This apparatus includes a pulsating, direct current, voltage mechanism that is operable to receive power from a single phase, alternating current voltage source, and a spiral wound filter capacitor, wherein the pulsating, direct current, voltage mechanism is electrically connected in parallel to the spiral wound filter capacitor and the spiral wound filter capacitor is electrically connected in parallel to the electrostatic precipitator. Optionally, a resistor is present to lower the transient voltage rating of the spiral wound filter capacitor. A switching mechanism may be utilized to apply differing amounts of capacitance and inductance in order to apply a range of voltage waveforms to the electrostatic precipitator to potentially maximize particulate collection efficiency for the electrostatic precipitator.

Abstract: The present invention provides an improved control method and apparatus allowing units arranged at different spaced apart locations to be controlled without the need for a high bandwidth link between the units and the controller. This allows a single controller to control a number of remotely located units.

Abstract: A single-stage converter improving power factor. The single-stage converter includes a power factor improving unit, a bridge diode unit, a voltage smoothing condenser, a transformer circuit unit, and a main switch. The power factor improving unit is connected to a input power source, the bridge diode unit is located next to the power factor improving unit and provides a current path, the voltage smoothing condenser stores electrical energy provided through the bridge diode unit, the transformer circuit unit is located between the bridge diode unit and the voltage smoothing condenser, and the main switch is connected to each of the bridge diode unit, the voltage smoothing condenser, and the transformer circuit unit and controls provision of voltage to the transformer circuit unit. Thus, the single-stage converter can improve the power factor of the input terminal.

Abstract: An apparatus for reducing electromagnetic interference due to common mode current in power converters is disclosed. Common mode current flowing through high parasitic capacitance on the load side typically contributes significantly to the electromagnetic interference. In order to reduce the electromagnetic interference the common mode current is reduced by reducing the voltage driving a current through the high parasitic capacitance. A counter-acting voltage source produces a voltage out of phase with the voltage driving the common mode current. Such a counter-acting voltage is obtained with the aid of a winding coupled to the magnetic component in the power converter or by one or more active components. The counter-acting winding is wound with the secondary and primary windings to share the same magnetic core.

Abstract: A low-ripple power supply includes a storage capacitor coupled across load terminals, and an inductor connected to a source of voltage including a varying or pulsatory component and a direct component, for causing a flow of current to said capacitor through the inductor. The varying component of the inductor current flowing in the capacitor results in ripple across the load. A winding is coupled to the inductor for generating a surrogate of the varying inductor current. The surrogate current is added to the inductor current to cancel or reduce the magnitude of the varying current component. This cancellation effectively reduces the varying current component flowing in the storage capacitor, which in turn reduces the ripple appearing across the load terminals.

Abstract: The invention relates to an RFI filter used for avoidance of mains retro-action in the form of radio noise. RFI filters are connected to frequency converters in order to reduce radio noise transmitted via conductors. These filters comprise large noise-decoupling capacitors which are connected to earth, and during start up of the frequency converter the capacitors cause leakage currents to earth. This gives rise to problems in those circumstances, where a circuit breaker is connected to a frequency converter and an RFI filter, because the leakage current is higher than the trigger current for the circuit breaker. The solution to this problem is to place a resistor in series with the noise-decoupling capacitor and parallel with the resistor to place a switch, which can be opened or closed with a control signal from a controller. The invention also concerns a method for activation of an RFI filter.

Abstract: A low-ripple power supply includes a storage capacitor coupled across load terminals, and an inductor connected to a source of voltage including a varying or pulsatory component and a direct component, for causing a flow of current to said capacitor through the inductor. The varying component of the inductor current flowing in the capacitor results in ripple across the load. A winding is coupled to the inductor for generating a surrogate of the varying inductor current. The surrogate current is added to the inductor current to cancel or reduce the magnitude of the varying current component. This cancellation effectively reduces the varying current component flowing in the storage capacitor, which in turn reduces the ripple appearing across the load terminals.

Abstract: An active EMI filter senses current in a ground line or a power transmission line as a voltage cross a capacitor coupled to the line. The EMI filter senses common mode voltage and determines a difference between the common mode voltage and noise to provide an output to drive the difference to zero. The resulting active closed loop EMI filter produces good EMI dampening with greatly increased performance over a current transformer type EMI filter. A voltage regulator for the error amplifier improves noise reduction while increasing filter efficiency. The active EMI filter operates in a wide linear range that is greater than that of an equivalent current transformer circuit, while providing low cost and reliability.

Abstract: An power supply apparatus for the input harmonic current suppression, input power factor compensation, and an output voltage regulation and a method thereof is provided. The power supply apparatus electrically connected to a AC power has a first power converter electrically connected in parallel with the AC power for providing a first compensating voltage and controlling the first compensating voltage to reduce harmonic components of an input current so as to cause the input current as a substantial sinusoidal wave and in phase with the input voltage, and a second power converter electrically connected in series with an output end of the power supply apparatus for providing a second compensating voltage in order to maintain the output voltage at a desired level and waveform. The related methods are also discussed.

Abstract: A device for converting electrical energy at a high operating frequency, supplied by an electrical network having a capacitor placed between a line and an earth of the device, the capacitance of the capacitor being such that the high-frequency noise is filtered and an inductor placed parallel to the capacitor and having a low resonant frequency corresponding substantially to the frequency of the electrical supply network. The device provide filtering in order to prevent the transmission of high frequency interference from the device to the electrical network while preventing, as far as possible, leakage currents through the filter. The device is useful in the electrical network for an X-ray apparatus.

Abstract: The present invention relates generally to the reduction of odd harmonics of phase angle controlled loads. One embodiment relates to an apparatus for reducing odd harmonic currents introduced into an alternating current (AC) supply by a load having a zero crossing detector and a processor coupled to the zero crossing detector. The zero crossing detector is coupled to the AC current supply for measuring voltage zero crossings of the AC current supply. The processor receives a user control signal for controlling the load, such as, for example, a speed control, determines phase angles required at the voltage zero crossings of the AC current supply to implement the user control signal, and selectively modulating the phase angles when they are in a predetermined range of undesired phase angles in order to selectively reduce odd harmonics within the AC current supply.

Abstract: A power supply is filtered while the amount of in-rush current required by the capacitive charging of the filter is limited. A resistor may be placed in parallel with a relay where the parallel combination is in series with the filtering capacitor. The relay is open upon applying power to the filter and remains open while the capacitor at least partially charges to cause charging current to pass through the resistor and thereby limit in-rush current. The relay is closed thereafter to provide a short circuit around the resistor and thereby unrestrict filtering by the capacitor. Alternatively, a common mode choke is disposed between a capacitor across input nodes and a capacitor across output nodes, whereby the size of the capacitors may be reduced to limit the in-rush current due to the common mode choke. The power supply filter may be included as part of a power distribution panel.

Abstract: For use with an electronic circuit having first and second reference nodes, a voltage reference translation system and a method of converting signals between the first and second reference nodes are provided. In one embodiment, the voltage reference translation system includes first and second inductors coupled to a common magnetic core and interposed between the first and second reference nodes. Additionally, the voltage reference translation system includes a conversion path coupled through a portion of the common magnetic core configured to substantially convert a signal associated with the first reference node into a signal associated with the second reference node.

Abstract: An apparatus and method to suppress a low speed ripple current to a motor include a power supply unit to supply single-phase alternating current (AC) power. A rectifying and smoothing unit rectifies and smoothes the single-phase AC power and outputs a direct current (DC) voltage indicative thereof. An inverter receives and converts the DC voltage to a motor driving current to drive the motor. A controller compares an envelope detected from a ripple current in the motor driving current and a DC component extracted from the ripple current and generates a compared result therefrom, and controls an output voltage from the inverter according to the compared result.

Abstract: An active EMI filter for reducing common mode current in a circuit comprising a rectifier coupled to an AC network, the rectifier supplying DC power to a DC bus, the DC bus feeding an inverter stage for providing AC power to a load, the load having a ground return line to a ground connection of the AC network, the active filter comprising: a transistor switching stage coupled across the DC bus, a current sensor coupled to the DC bus for sensing the common mode current flowing in the DC bus and proportional to the common mode current flowing in the ground return line from or to the load, the current sensor having inputs coupled to respective legs of the DC bus and an output driving the transistor switching stage, the transistor switching stage comprising two transistors driven by said output of the current sensor whereby one of said transistors is turned on by said current sensor output depending on the direction of common mode current in said DC bus, a capacitor coupling said transistor switching stage and sa

Abstract: A power supply is filtered while the amount of in-rush current required by the capacitive charging of the filter is limited. A resistor may be placed in parallel with a relay where the parallel combination is in series with the filtering capacitor. The relay is open upon applying power to the filter and remains open while the capacitor at least partially charges to cause charging current to pass through the resistor and thereby limit in-rush current. The relay is closed thereafter to provide a short circuit around the resistor and thereby unrestrict filtering by the capacitor. Alternatively, a common mode choke is disposed between a capacitor across input nodes and a capacitor across output nodes, whereby the size of the capacitors may be reduced to limit the in-rush current due to the common mode choke. The power supply filter may be included as part of a power distribution panel.

Abstract: A noise canceling circuit that eliminates noise from an AC current of an AC power supply is provided with a changeover device that brings the noise canceling circuit into and out of conduction with a secondary side of a transformer in accordance with an on-off state of a switch. The noise canceling circuit includes a filter portion. The changeover device may be a relay or triac.

Abstract: A noise filter 10 of the present invention includes an inductor 71 and a resistor 11 connected in parallel with each other. A power supply frequency current bypasses the resistor 11 but passes through the inductor 71. A high frequency noise current including a resonance frequency current, on the other hand, bypasses the inductor 71 but is dissipated at the resistor 11. Therefore, the noise filter 10 does not accumulate noise power and so does not suffer from a problem due to power releasing. The resonance frequency current caused by combination of inductance of the inductance and earth capacitance in the noise filter 10 is also dissipated at the resistor 11, thus giving rise to no problem of its own.

Abstract: Conductive EMI in motor drive circuits is reduced by interposing inductors in the ground line. The common mode current enters the motor drive circuit through the two supply leads and leaves the system through the ground lead. The ground current typically is very high frequency but very low in rms amperage. Interposing an induction (low current, very high L) in the ground line advantageously reduces EMI. The inventive method reduces.or eliminates the need for filtering capacitors across the rectifier of the motor drive circuit. In addition, the inventive method minimizes the common mode choke to merely a wraparound ferrite core over the input wires. EMI emissions are reduced further by sandwiching ground traces along with power traces and connecting to.the heat sink with the shortest possible route. This reduces the ground loop area, which consequently reduces emissions.

Abstract: The voltage applied to a power converter is detected by a voltage detector, a function generator produces a voltage proportional to this detected voltage, and a high-pass filter detects an AC component superimposed on the voltage. An adder adds a bias voltage to this AC component, and an adder adds the output from the adder and the output from the function generator. The output from the adder is compared with a triangular wave produced from a rectangular wave generator, and a switching element is controlled to make switching operation according to the compared result. When a DC current is decreased by the AC component, a resistance current Ib is increased so that the AC components superimposed on the current and resistance current can be cancelled out.

Abstract: A space-efficient power supply powers a system and is housed in a small area of the system. The components of the power supply are designed to reduce heat generation and be aerodynamically efficient. Reduced heat generation reduces the need for air space around the power supply for cooling air, thus allowing the power supply to be housed in a small space. And because the components are aerodynamically efficient, space requirements are further reduced. In one embodiment the power supply is used in a system to power secondary power supplies. The secondary power supplies provide isolated power to components of a system, such as a communications system in an equipment box. In another embodiment, the power supply is used in an equipment box to power communications equipment distributed in the equipment box.

Abstract: A harmonic mitigating apparatus connected between a three phase power source and a load provides a multiple-winding reactor for reducing harmonics directed from the load to the source, the apparatus including, for each system phase, first and second line windings in series between the source and load and oriented so as to have the same polarity such that the winding fluxes add thereby increasing total reactance to harmonics directed from the load to the supply, the apparatus also including at least one trap circuit including a series inductance and capacitor for each phase and linked between the first and second line windings and a neutral point (or another phase), the trap circuit characterized by a reactance that is lower than the reactance of the first line winding such that harmonics flow into the trap circuit, for each phase, at least two of the first and second line windings and the trap winding arranged on the same core.

Abstract: A DC matrix converter having six forward current conducting power switches and six reverse current conducting power switches has the on time duration of each power switch within a pulse width modulation period controlled by relationships between d and q components of a modulation index determined by the ratio of a voltage command to the instantaneous voltage of the AC mains expressed in stationary dq coordinates, the selection of which is made based on inequalities between the DC main voltage components expressed in stationary dq coordinates. Switch selection is also performed in response in relationships of the AC main voltage components expressed in stationary dq coordinates. Zero vectors are selected to minimize the common mode voltage.