Abstract: An AC/DC converter includes a rectifier circuit, at least one restraining unit, and a power interruption detection circuit. The rectifier circuit is used for converting an AC (alternating current) to a DC (direct current) power source. The restraining unit is connected to an output terminal of the AC power supply. The restraining unit includes a resistor and a switch connected in parallel. The power interruption detection circuit detects whether an input power cycle is regular. When the input power cycle is interruptive, a signal is generated to change a state of the switch in the restraining unit to make the resistor of the interfere in the circuit to restrain an inrush current in any operational circumstance, such as warm startup or quick startup.

Abstract: There is provided a power supply for AC/DC and DC/DC conversion which receives the DC power supplied from airplanes, vehicles and vessels as well as normal AC power, and converts the power to DC power and supplies it to portable electronic products. The power supply for AC/DC and DC/DC conversion includes an AC input 10, a DC input 20, a switch 30 for selecting AC input power or DC input power, a DC output 40, and a circuit used for AC/DC and DC/DC conversion 100 which converts the power input from the AC input or the DC input to DC power having predetermined values of current and voltage, and a secondary side of a transformer (TL) for AC/DC conversion inside the circuit for conversion serves as an inductor for performing DC/DC conversion.

Abstract: Systems and methods are described for controlling power factor in motor drives having a switching rectifier providing a DC link current to an inverter in which the rectifier gain is increased to provide additional DC link current to correct the drive power factor based on current drawn by capacitors of the AC drive power input, and the inverter gain is decreased by introducing bypass states in the inverter switching control scheme or by reducing the motor flux to accommodate the increased DC link current.

Abstract: A three-phase voltage-fed AC/DC converter includes a conversion circuit which converts power from a DC voltage source to three-phase AC power. The converter further includes a UM conversion circuit which carries out dq conversion of the three-phase output voltage, a superior voltage control circuit which outputs a voltage reference vector based on a superior reference vector and an output voltage vector obtained by the UM conversion circuit, an inferior voltage control circuit which outputs a PWM reference based on the voltage reference vector and the output voltage vector, and a frequency control circuit which synchronizes a value generated based on a q-axis component from the UM conversion circuit with a rotation angle of a conversion matrix in the UM conversion circuit.

Abstract: A method for controlling/regulating a physical variable of a dynamic system to a specific desired value profile with use made of a pulse modulator that generates a sequence of discrete modulation signals that affect the control or regulation of the physical variable. The method involves repeated execution of: determining an exact value or an approximation for the deviation between the momentary desired value and the momentary actual value of the physical variable; determining the respective change in the deviation which would result from the maintenance of the momentary modulation signal or the switching over to the other modulation signals; and generating that modulation signal which results in the best approximation of the momentary desired value.

Abstract: The difference between internal processes of a power converting apparatus may bring about a heat difference in the apparatus. In the cooling process, it is presumed that the temperature change of the inverter or converter module may be made so great that the power converting apparatus may be less reliable. In order to overcome this shortcoming, the temperature of the internal module is measured and a cooling control of a cooling fan or the like is carried out on the measured result. This cooling control of the cooling fan causes the life of a switching element of the inverter or converter to be longer.

Abstract: A converter includes a converter circuit 1 having a plurality of bridge-connected semiconductor switching devices for converting AC power into DC power, a smoothing condenser connected in parallel to the DC side of the converter circuit and a current detector provided in a condenser circuit to control a condenser current flowing through the smoothing condenser to be a set value. The condenser current is controlled to be the set value (e.g. zero) to thereby reduce the capacity of the smoothing condenser and make the converter small.

Abstract: An inverter converts input voltage to AC driving voltage to supply it to a load. Secondary coil of an output transformer are connected to the load. Secondary coil of a main transformer are connected to the primary coil of the output transformer. A driving circuit applies switching voltage alternately repeating the input voltage and ground voltage to the primary coil of the main transformer.

Abstract: A matrix converter may be provided with AC switches that comprise bi-directional sets of semiconductor switches that are gated with a common gating link. A low loss diode-bridge based snubber may facilitate introduction of time delay between sequential operations of the bi-directional set of semiconductor switches. The matrix converter may be operated in a three-phase mode with only one gating signals for each AC switch, in contrast to prior-art matrix converters which may require use multiple gating signals for each AC switch.

Abstract: A power converter is provided with a rectifying circuit, an inverter circuit, and a common mode filter including a common mode choke coil and a capacitor. The switching frequency of a PWM rectifying circuit is set at three times the switching frequency of a PWM inverter. Alternatively, the resonance frequency of the common mode filter is set at twice the carrier frequency of the rectifying circuit or the PWM inverter circuit or more.

Abstract: An outlet (70, 75, 76, 78, 79) for a Local Area Network (LAN), containing an integrated adapter (21, 25) that converts digital data to and from analog video signal. Such an outlet allows using analog video units in a digital data network (80), eliminating the need for a digital video units or external adapter. The outlet may include a hub (31, 41) that allows connecting both an analog video signal via an adapter, as well as retaining the data network connection, which may be accessed by a network jack (73). The invention may also be applied to a telephone line-based data networking system. In such an environment, the data networking circuitry as well as the analog video adapters are integrated into a telephone outlet, providing for regular telephone service, analog video connectivity, and data networking as well. In such a configuration, the outlet would have a standard telephone jack (71), an analog video jack (72) and at least one data networking jack (73).

Abstract: An electrical energy transmission device has phase conductors, which carry alternating current and have transfer impedance, and sheathed conductors, which are inductively coupled to the phase conductors. A first end and a second end of each sheathed conductor form a sheath circuit with a reactance. An electronic assembly for changing the impedance of the sheath circuit is provided. The electrical energy transmission device can be used flexibly given different demands placed on the energy transmission. The electronic assembly is also configured to increase the transfer impedance.

Abstract: An input voltage Vc to a bridge circuit is made variable by making a switching element, which is on a lower side among a plurality of switching elements constituting the bridge circuit, a coil and a capacitor, which constitute a filter, operate as an active filters at the time of charging the battery.

Abstract: A hybrid power supply system including piezoelectric and ferrite transformers for driving a discharge lamp is provided. Specifically, the hybrid power supply system includes a rectifier/filter, a piezoelectric inverter, and a ferrite converter. The rectifier/filter has an input terminal connected to an external AC voltage to convert the external AC voltage to a DC voltage. The piezoelectric inverter is connected to the rectifier/filter to step up and convert the DC voltage to an AC voltage for driving the discharge lamp. The ferrite transformer is connected to the rectifier/filter to step down the DC voltage to a rated DC voltage for driving discharge lamp circuits other than the discharge lamp. The piezoelectric inverter and the ferrite converter are integrated by connecting a primary side of the piezoelectric step-up transformer and a primary side of the ferrite step-down transformer in series or in parallel with an output terminal of switching circuits.

Abstract: A power conversion apparatus for converting power from an alternating source to dc includes an input stage for receiving power from the alternating source, which includes an input filter, a rectifier for rectifying the alternating signal, a capacitor for storing energy from the rectified signal, and an output for outputting power from the rectifying means and the capacitor to the pulsed load. The pulsed load has at least one switched winding which receives power from the output, and wherein the capacitor is configured such that the voltage across the capacitor falls below 15% of the nominal peak rectified voltage of the source during each cycle of the alternating source. A converter of this kind provides benefits in that the current drawn from the ac supply falls within limits imposed by regulations and is simpler and cheaper than known converters of a similar power rating.

Abstract: One system of the present application includes an electric power generation device structured to provide an AC electric power output at a target frequency. This device includes: an electric power generator; a sensing arrangement structured to provide samples corresponding to magnitude of the AC electric power output; and a controller including operational logic responsive to the sensing arrangement to calculate a peak amplitude as a function of a waveform period corresponding to the target frequency and two of the samples separated in time by a target duration of 20 to 30 percent of the waveform period and determine a zero crossing of the output from the peak amplitude and the target frequency. The operating logic is further structured to control operation of the device in accordance with the zero crossing.

Abstract: An outlet for a Local Area Network (LAN), containing an integrated adapter that converts digital data to and from analog video signal. Such an outlet allows using analog video units in a digital data network, eliminating the need for a digital video units or external adapter. The outlet may include a hub that allows connecting both an analog video signal via an adapter, as well as retaining the data network connection, which may be accessed by a network jack. The invention may also be applied to a telephone line-based data networking system. In such an environment, the data networking circuitry as well as the analog video adapters are integrated into a telephone outlet, providing for regular telephone service, analog video connectivity, and data networking as well.

Abstract: A motor driving apparatus drives a motor by means of an AC/AC direct converter such as a matrix converter. The motor driving apparatus is provided with a current detecting section for detecting motor currents, a comparing section for detecting whether motor current detection values have exceeded a restriction level, an induction voltage calculating section for calculating induction voltages of the motor, a switching section, and a PWM pattern generating section. When the comparing section detects that the motor current detection values have exceeded the restriction level, the switching section supplies the induction voltages calculated by the induction voltage calculating section to the converter as output voltage instruction values.

Abstract: A power control interface between an unstable power source such as a wind farm and a power transmission line employs an electrical energy storage, control system, and electronic compensation module which act together like an “electronic shock absorber” for storing excess power during periods of increased power generation and releasing stored energy during periods of decreased power generation due to wind fluctuations. The control system is provided with a “look ahead” capability for predicting power output (wind speed conditions) and maintaining energy storage or release over a “narrow-band” range despite short duration fluctuations. The control system uses data derived from monitoring the wind farm power output and the power transmission line, and employs system-modeling algorithms to predict narrow-band wind speed conditions.

Abstract: A device for transforming an AC voltage to a lower AC voltage includes a generator of a PWM control signal and a first bidirectional switch to couple a load to the AC voltage during a conduction-phase. A second bidirectional switch discharges energy from the load during an off-phase of the first bidirectional switch. A first driving circuit of the first bidirectional switch is input with the PWM control signal and generates a first PWM signal, applied between control and conduction terminals of the first bidirectional switch. A second driving circuit for the second bidirectional switch is input with the PWM control signal and generates a second PWM signal, in phase opposition to the first PWM signal, applied between control and conduction terminals of the second bidirectional switch. An electric decoupling circuit is between the generator and second driving circuit. A transformer is between respective conduction terminals of the bidirectional switches.

Abstract: An energy recycle system for use with an AC current power supply, for example, an electronic ballast, is presented. The energy recycle system includes an energy recycle load connected to an output terminal of the AC current power supply, in which the energy recycle load includes a rectifier for rectifying the output AC current of the AC current power supply into a rectified DC current and a filter connected to the rectifier for removing the high-frequency harmonics from the rectified DC current. Also, the energy recycle system further includes a DC-AC converter connected to the energy recycle load for receiving the DC current outputted from the energy recycle load, which is in turn delivered to the utility grid to achieve energy recycling.

Abstract: A medium or high voltage multi-inverter system is described, in which multiple inverter cells are included in a phase line to increase the voltage level supported by the system, and support higher voltage loads such as AC three-phase motors. In one configuration, five cells are used: two each in two phase lines, and one in a third phase line. In one of the phase lines having two cells, a second cell is series connected in reverse polarity, generates a phase matching the phase of the third line, while the other cell in the phase line generates an output with a different phase. One or more failure switches may be included to allow for short-circuiting of the output poles of one or more of the cells, so that in case of cell failure, the system can continue operation. For example, switches may be employed for the second cells in the two phase lines having two cells, and those cells may be available as spare cells in case of a cell failure.

Abstract: A power supply to provide electrical power to one or more loads. The power supply may include a resonant air core transformer to provide an adjustable and adaptable source of power to electronic devices. The power supply may include isolated primary-side circuitry and secondary-side circuitry. The primary-side circuitry may include control circuitry that, among other things, provides drive waveforms for the primary-side switching circuitry. In embodiments configured to produce AC output, the secondary-side circuitry may also include switching circuitry. The primary-side control circuitry may provide drive waveforms for the secondary-side switching circuitry. The secondary-side circuitry may include measurement circuitry that measures the current and/or voltage of the output and provides those measurements to the control circuitry through isolation circuitry. The control circuitry may adjust the drive waveforms for the primary-side and/or secondary-side switching circuitry as a function of the measured values.

Abstract: A variable speed drive is provided having a converter to convert an AC voltage to a DC voltage, a DC link to filter and store energy from the converter, and a plurality of inverters. Each inverter is configured to convert a DC voltage to an AC voltage and is electrically connected in parallel to the DC link. An interleaved pulse width modulation control technique is used to control the operation of the plurality of inverters and possibly the converter to lower the RMS ripple current in the DC link.

Abstract: It is possible to easily and rapidly develop an inverter application while maintaining stable quality. Executable code modules which have been sufficiently tested are installed in an inverter. An application source code is created on a programming device by using function blocks corresponding to the executable code modules and connection lines for connecting the function blocks. The source code is complied to create a connection information table for selecting the executable code modules and specifying their execution order. The connection information table is downloaded to the inverter via communication to execute the application.

Abstract: A noise suppressor capable of preventing degradation in an attenuation characteristic by a parasitic component so as to obtain a favorable attenuation characteristic is provided. The noise suppressor includes a first winding wire disposed on a first current-carrying wire and a series circuit including a capacitor and a second winding wire which are connected to each other in series. The first winding wire and the second winding wire are magnetically coupled to each other. The inductance xL of the whole second winding wire is smaller than the inductance LL of the whole first winding wire (xL<LL). Moreover, it is desirable that the inductance xL of the whole second winding wire is equal to or smaller than the inductance LL1 per turn in the first winding wire (xL?LL1).

Abstract: In the preferred embodiments, an uninterruptible power supply has multiple UPS modules connected in parallel. Each module has an AC-DC-AC converter and a subcontroller for controlling the operation of the AC-DC-AC converter. A single current sensor senses a total aggregate current flowing from all the modules. Each subcontroller can detect an input voltage, output voltage, and DC bus voltage of each module. Also, each module has unique operating characteristics (e.g., efficiency curve and a responsiveness coefficient K). Operating characteristics data are stored in a memory accessible by the subcontroller. Based on the voltage and current measurements, and the operating characteristics of each module, the subcontrollers perform calculations to determine a DC bus voltage target (unique for each module) that results in each module providing the same output current. Accordingly, only one current sensor is needed, and, consequently, the cost of the UPS device can be reduced.

Abstract: A drive system for a vehicle moving along a trackway, particularly a magnetic levitation train, includes a linear motor which has a stator extending along the trackway, and can be connected to a three-phase output voltage of an output transformer. An electrical power supply supplies a three-phase supply voltage which is converted into a three-phase alternating voltage of predeterminable frequency and amplitude by a converter unit. The alternating voltage being connected to the primary winding of an output transformer. To provide for more differentiated power adaptation it is proposed that the secondary winding of the common output transformer be provided with taps which, in transformer mode, can be connected and disconnected by a stepping switch for adjusting and correcting the desired output voltage.

Abstract: An inverter apparatus can lengthen a lift span and improve efficiency. Instead of a conventional electrolytic capacitor, only a noise absorption film capacitor is provided in a DC intermediate circuit between rectifying and inverter circuits. In a voltage command generating unit, when a frequency set by a frequency setting unit is within a predetermined range including the frequency of an AC input power supply, PLL control is performed to make the frequency set by an output voltage command signal equal to the frequency of the AC input power supply voltage, and to substantially synchronize the peak value of an output voltage from the inverter circuit with the peak value of a voltage formed between both ends of the film capacitor. Accordingly, output voltage amplitude is generated when the frequency set by the output voltage command signal equals the frequency of the voltage of the AC input power supply.

Abstract: An uninterruptible power supply (UPS) includes an AC power source, a DC power source coupled to a DC bus, a load, a converter, an inverter and a controller. Responsive to the controller, the inverter receives power from the DC bus to supply the load a regulated voltage; the converter, operated in a hybrid mode, receiving power from the AC power source to supply the DC bus a regulated DC voltage in a double conversion mode or to supply the power to the load in a series-parallel mode, or a combination of the two modes. In the stored energy mode, with an additional bypass switch, both the converter and inverter receive power from the DC power source and jointly supply the load a high quality voltage. These configurations improve the efficiency and enable the UPS readily meet the VFI and the high quality output voltage requirements per IEC62040-3.

Abstract: A wind turbine is provided, the wind turbine comprising, a synchronous generator having a stator and a rotor, an AC-DC-AC link for coupling said synchronous generator to a grid, wherein the DC link is connected to the rotor of said synchronous generator for supplying an excitation voltage to a rotor winding of said rotor. Furthermore, a method of starting a wind turbine with an electrically excited synchronous generator is provided, the method comprising the steps of (a) opening a grid contactor; (b) closing a bypass contactor to bypass a grid-side DC-AC inverter of said wind turbine; (c) charging a DC link of said wind turbine; (d) supplying an excitation voltage to rotor windings of said synchronous generator, wherein said excitation voltage is supplied from the DC link; and (e) opening said bypass connector and closing said grid connector.

Abstract: Inverter-filter non-linearity blanking time and zero current clamping compensation is accomplished by comparing the average output current with the discontinuous current mode threshold values to determine when the average output current is entering a discontinuous current mode and introducing a compensation voltage to the inverter drive voltage in response to the average output current entering a discontinuous current mode to compensate for discontinuous current mode distortion of the inverter output voltage.

Abstract: This invention disclosed is a comprehensive power quality controller for substation in the electric power system and includes a Thyristor Controlled Reactor (TCR), pure tuned passive filter Zf, additional inductor L active power filter (APF), and a coupling transformer. The Thyristor Controlled Reactor (TCR) provides inductive reactive power and controls the active power filter (APF) as the current source, it is connected with the additional inductor La in parallel via the coupling transformer, then connected to the passive filter Zf in serial to consist a hybrid power filter system, which is connected to the power grid via the circuit breaker or thyristor. The comprehensive filter system provides required capacitive reactive power and filters the harmonic produced by the load and TCR system itself. Because the capacity of the active power filter (APF) is very small which is less than 1% of the harmonic source capacity, so it is a solution with low cost but simple and reliable control mode.

Abstract: A DC/AC converter circuit structure for driving a plurality of cold cathode fluorescent lamps is described. A common-mode choke is used between the cold cathode fluorescent lamps. The common-mode choke balances the currents respectively flowing through the cold cathode fluorescent lamps.

Abstract: A rectifier includes a switching circuit and a controller. The switching circuit is coupled between positive and negative buses and a plurality of input voltage sources. The switching circuit includes a plurality of pairs of switching devices. Each pair is associated with one of the input voltage sources. The controller includes first and second control loops operable to generate control signals for operating the pairs of switching devices to generate a potential across the positive and negative buses. The controller is further operable to estimate a line inductance seen by the rectifier based on at least one of the control signals and generate an inductance compensation gain factor for applying to the control loops based on the estimated line inductance.

Abstract: Variable speed drive comprising a main rectifier module (10) including thyristors (K1, K2, K3) to power a main continuous bus (15) from an external power network (5), an inverter module (30) delivering a variable control voltage to an electric motor from the main bus (15), an auxiliary rectifier module (20) connected to the external power network (5), an electronic control unit (50) controlling the thyristors, a powering module (29) supplying the control unit (50) from the auxiliary rectifier module (20) and from the main rectifier module (10). According to the invention, a switching device (40) controlled by the control unit (50) is used to disconnect the powering module (29) and the auxiliary rectifier module (20).

Abstract: Disclosed are a power supplying apparatus and a LCD having the same that reduces manufacturing cost of a large-scale LCD module and enhances powpower efficiency by integrating an external dc power supply used in a large-scale LCD panel into a LCD panel. A first voltage converter converts an external ac voltage into a first dc voltage, and changes a voltage level of the first de voltage into a second dc voltage having a highr voltage level than that of the first de voltage. A second voltage converter converts the second dc voltage into an ac voltage, raises a voltage level of the converted ac voltage, and provides the raised ac voltage to a load. A current detector detects a current flowing through the load, and provides a current detection signal as a feedback signal to the first voltage converter so that the first voltage provide a constant direct current output voltage.

Abstract: An power supply circuit (2) includes a bridge rectifier circuit (22); a control circuit (23) having a switch circuit (231) and a pulse width modulation circuit (232); a high frequency transformer (24); at least one commutating and filter circuit (25); and a positive feedback circuit (29). An alternating current voltage input from an external source is converted into a high frequency direct current voltage via the bridge rectifier circuit, and the high frequency DC voltage is outputted from the power supply circuit via the switch circuit, the high frequency transformer, and the at least one commutating and filter circuit. The positive feedback circuit receives the high frequency DC voltage outputted by the bridge rectifier circuit and transmits the high frequency DC voltage to the pulse width modulation circuit, and the pulse width modulation circuit controls a conduction time of the switch circuit according to the received high frequency DC voltage.

Abstract: An active type harmonic suppression apparatus, connected in parallel to a power feeder, supplies a compensation current for injecting into the power feeder such that a utility current of a power source is approached to a sinusoidal wave. The control circuit retrieves a load current, a utility current, an output current of the power converter, a power source voltage and a voltage of the dc power capacitor for calculating and sending a reference signal of compensation voltage to a pulse-width-modulation circuit which generates switching signals for the power converter. Furthermore, the harmonic suppression apparatus can provide a fixed or variable reactive power.

Abstract: A method of protecting a frequency converter against overvoltage by controlling an AC motor during braking or during light load and a frequency converter, wherein the frequency converter is a voltage-controlled PWM frequency converter operating in single quadrant (1Q) and comprising at least one uncontrolled rectifier bridge (10) to be connected to a AC supply line (UL1, UL2, UL3), a direct-voltage intermediate circuit and at least one controlled inverter bridge (11) for feeding an AC motor (12) with an alternating voltage (Uu, Uv, Uw) of varying magnitude and frequency, in which method: the angle (??) between the output voltage vector (Us) and current vector (Is), i.e. the power factor, is measured, the angle (??) between the output voltage vector (Us) and current vector (Is), i.e. the power factor, is controlled on the basis of the measurement, and the angle (??) between the output voltage vector (Us) and current vector (Is), i.e.

Abstract: A power supply for point-of-sale (POS) devices. The power supply comprises a transformer with first through fourth windings. An AC input is connected through a backfeed relay to the first winding. An AC output is also connected to the first winding. A battery and an inverter are connected to the second winding. A charger is connected to the third winding. A rectifier, DC/DC regulator and a DC output are connected to the fourth winding. When AC power is received at the AC input, the AC output and the transformer receive the AC power through the backfeed relay. The DC output receives DC power through the DC/DC regulator and the rectifier, which receives AC power through the transformer. When AC power is not received at the AC input, the battery and the inverter provide AC power to the transformer, and the AC output and the rectifier receive AC power from the transformer. The DC output receives DC power through the DC/DC regulator and the rectifier.

Abstract: A ring balancer comprising a plurality of balancing transformers facilitates current sharing in a multi-lamp backlight system. The balancing transformers have respective primary windings separately coupled in series with designated lamps and have respective secondary windings coupled together in a closed loop. The secondary windings conduct a common current and the respective primary windings conduct proportional currents to balance currents among the lamps. The ring balancer facilitates automatic lamp striking and the lamps can be advantageously driven by a common voltage source.

Abstract: A power converter including a hardware efficient control loop architecture. Error detection circuitry may generate an error signal based on the difference between a power converter output voltage and a reference voltage. An oversampling ADC may digitize the error signal. The transfer function associated with the ADC may include quantization levels spaced at non-uniform intervals away from a center code. A digital filter may calculate the average of the digitized error signal. A nonlinear requantizer may reduce the number of codes corresponding to the output of the digital filter. A proportional integral derivative (PID) unit may multiply the output of the nonlinear requantizer by PID coefficients to generate a PID duty cycle command, and a gain compensation unit may dynamically adjust the PID coefficients to maintain a constant control loop gain. A noise-shaped truncation unit including a multi-level error-feedback delta sigma modulator may reduce the resolution of the PID duty cycle command.

Abstract: A circuit for protecting against controller failure wherein the controller provides control signals for controlling a DC to AC inverter fed by a DC bus and driving a permanent magnet motor, the circuit comprising a first circuit for monitoring the DC bus voltage and, in the event the DC bus voltage exceeds a first threshold due to a counter EMF generated by the motor, for producing a signal to the controller to provide a switch state to the inverter whereby the counter EMF is dissipated substantially in a motor circuit resistance of the permanent magnet motor as a result of a short circuit condition provided by the switch state of the inverter, thereby preventing the DC bus voltage of the inverter from exceeding the first threshold and causing the permanent magnet motor speed to be reduced.

Abstract: A method of and system for regulating voltage supplied by a local power supply to a remote load includes sensing a low frequency portion of the output voltage at the remote load, locally sensing a high frequency portion of the output voltage produced by the local power supply, and in response, controlling the output of the supply.

Abstract: A DC/AC converter circuit structure for driving a plurality of cold cathode fluorescent lamps is described. A common-mode choke is used between the cold cathode fluorescent lamps. The common-mode choke balances the currents respectively flowing through the cold cathode fluorescent lamps.

Abstract: A variable speed drive is provided having a converter to convert an AC voltage to a DC voltage, a DC link to filter and store energy from the converter, and a plurality of inverters, wherein each inverter is configured to convert a DC voltage to an AC voltage to power a corresponding load connected to the inverter The converter is electrically connected to an AC power source, the DC link is electrically connected to the converter, and the plurality of inverters are electrically connected in parallel to the DC link. Each inverter of the plurality of inverters is configured to operate substantially independently of other inverters of the plurality of inverters.

Abstract: In dynamic voltage sag correctors and other power conversion equipment having a DC bus that is subject to over-voltage conditions due to power being fed back by a regenerative load, a bus discharge switching device and a discharge resistor are connected in series across the DC bus lines. The discharge switching devices are switched on to discharge the energy storage device connected to the bus, or to separately discharge the two capacitors of a split capacitor DC bus, to eliminate the over-voltage conditions. The discharge switching devices may be switched on and off periodically with a selected duty cycle to discharge energy from the energy storage capacitor or other energy storage device through the discharge resistor at a rate which does not exceed the power rating of the discharge resistor. The discharge switching device may be switched with a fixed duty cycle or with a variable duty cycle that is based on the dynamic power dissipation characteristics of the discharge resistor.

Abstract: There is provided an adjustable integral component in a feedback loop of a closed loop control system. The closed loop control system controls an output signal of an electric generator. The adjustable integral component provides an integral signal. The integral signal is proportional to the output signal in a first operational mode. The integral signal is proportional to a time integral of an output signal in a second operational mode. According to another aspect of the invention there is provided a non-linear component in a feedback loop of a closed loop control system. The closed loop control system controls an output signal of an electric generator. The electric generator having non-linear characteristics. The feedback loop has an error signal, of which the output signal is responsive to. The non-linear component receives a load signal and provides a non-linear signal related to the non-linear characteristics of the electric generator. The error signal is responsive to the non-linear signal.

Abstract: A digitally controlled hybrid power module is controlled by a programmable controller. The hybrid power module includes a digitally controlled switching supply with an output coupled to an input of a digitally controlled linear voltage regulator. Independent control of switching supply and the linear regulator is provided by the programmable controller, which may be a field programmable gate array (FPGA), microcontroller, or digital signal processor (DSP). The programmable controller may independently control one or more power modules. Each power module may also include enable switching and an associated current clamp for capacitive loads. An output voltage transient suppressor may also be used to control transients, such as those produced under fast switching conditions.