Abstract:
Driver circuit in which a capacitor (4), in a manner controlled by a switch control device (9) which is connected downstream of a current measuring device (8), is charged to a reference voltage (Ur) by means of a charging current (Ic2), and the charged capacitor is discharged in an oscillating manner via an inductor coil (1), wherein the discharging operation is terminated when the current (Ia) through the inductor coil has passed through an entire oscillation period or several oscillation periods, wherein a first controllable switch (5) is connected in series between a first non-reactive resistor (6) and the first capacitor (4) in one of two input paths. Furthermore, a second controllable switch (7) and a fourth controllable switch (14) are connected into two output paths, and a second non-reactive resistor (13) is connected between a second connection (X2) of the inductor coil (1) and a connection for Na reference potential (Um). The current measuring device (8) is connected between the fourth controllable switch (14) and the first capacitor (4).
Abstract:
A fault current limiter may include a current limiting leg to transmit a first current and a control leg in parallel with the current limiting leg, the control leg to transmit a second current. The control leg may include a plurality of solid state switches arranged in electrical series with one another; a plurality of current monitors arranged in electrical series with the plurality of solid state switches; and at least one triggering circuit, wherein the plurality of current monitors are electrically coupled to the at least one triggering circuit, and wherein the at least one triggering circuit is optically coupled to the plurality of solid state switches.
Abstract:
Various embodiments are described herein for methods and systems of regulating incoming voltage supplied from a utility power supply to a load. In one example embodiment, a voltage regulator adapted to be electrically interposed between the utility power supply and the load, each having at least one phase, is provided. The voltage regulator comprises an autotransformer having, for each phase, a series winding and a regulating winding, where the regulating winding has a plurality of taps and the series winding has a load side for connection to the load and a supply side for connection to the utility power supply. The voltage regulator comprises a controller coupled to the autotransformer, where the controller is configured to operate the voltage regulator in a zero voltage reduction mode and an autotransformer mode, and where the controller comprises a zero voltage reduction mode switch connected across a first subset of at least two taps of each regulating winding and a normally closed contactor connected across a second subset of at least two taps of each regulating winding.
Abstract:
A switching device is provided for disconnecting or connecting an electric machine, a converter or a plurality of electrical loads supplied with AC power from a power supply and controlled by a control unit. The switching device includes a current sink and at least one mechanical switch in the switching device are arranged in a circuit. The current sink is arranged, upon receipt of a signal, to close and sink the current, and the at least one mechanical switch is arranged to open and break the current on receipt of a signal to open supplied to the electric machine when the current load is at or close to zero. A method and a computer program for carrying out the method are described.
Abstract:
In at least one embodiment, the controller senses a leading edge, phase cut AC input voltage value to a switching power converter during a cycle of the AC input voltage. The controller senses the voltage value at a time prior to a zero crossing of the AC input voltage and utilizes the voltage value to determine the approximate zero crossing. In at least one embodiment, by determining an approximate zero crossing of the AC input voltage, the controller is unaffected by any disturbances of the dimmer that could otherwise make detecting the zero crossing problematic. The particular way of determining an approximate zero crossing is a matter of design choice. In at least one embodiment, the controller approximates the AC input voltage using a function that estimates a waveform of the AC input voltage and determines the approximate zero crossing of the AC input voltage from the approximation of the AC input voltage.
Abstract:
A control system includes a zero crossing detecting circuit for detecting a zero crossing of an AC signal. The circuit includes a transformer having a primary portion and a secondary portion. The primary portion receives the AC signal. The secondary portion comprises first and second terminals. The first terminal is biased at a first DC voltage level. An output switch is operatively connected to the second terminal and has an on state and an off state. The output switch selectively activates an output signal of the zero crossing detecting circuit according to an activation voltage level sensed by the output switch and corresponding to the zero crossing. While in the off state, the output switch is biased at a second DC voltage level. A voltage difference between the first and second DC voltage levels substantially equals the activation voltage level. A controller monitors the output signal and controls an operation based on the output signal.
Abstract:
A zero-crossing detecting device that detects a zero-crossing point of AC voltage, the device has a full-wave rectifier that rectifies the AC voltage and outputs a full-wave rectified voltage, a charger that is charged at a predetermined charging voltage by application of the full-wave rectified voltage, wherein the charger outputs a charging current when the full-wave rectified voltage falls below the charging voltage, and a signal output part that outputs a zero-crossing detecting signal. The signal output part outputs the zero-crossing detecting signal when the charging current flows to the signal output part.
Abstract:
A circuit for controlling two switches assembled in anti-parallel, comprising in series between two terminals of the anti-parallel assembly, two identical control stages respectively dedicated to each switch and between which is interposed a common impedance setting a phase angle for the turning-on of the switches, each stage comprising: a controllable current source for providing a current to a control electrode of the concerned switch; a capacitor for storing a supply voltage of at least the current source; an element of activation/deactivation of a the current source according to the voltage across the stage capacitor; and an assembly for discharging the capacitor.
Abstract:
A circuit technique substantially reduces the switching losses of a pulse-width-modulated (PWM) converter caused by the turning-on (closing) and turning-off (opening) characteristic of the switch and the reverse-recovery characteristic of the rectifier. The losses are reduced by using a new switch cell which includes a snubber inductor, a clamp diode, a clamp capacitor, a main switch, and an auxiliary switch. The reverse-recovery-related losses are reduced by the snubber inductor connected in series with the main switch and the rectifier to control the rate of change of rectifier current during its turn-off. In addition, the main switch operates with zero-current and zero-voltage switching, while the auxiliary switch operates with zero-voltage switching. A proper operation of the proposed circuit requires overlapping gate drives of the main and the auxiliary switches. The circuit technique can be applied to any member of the PWM converter family.
Abstract:
A method of and apparatus for controlling the opening and/or closing of contacts of an electro-mechanical switching device in an alternating current circuit. Detection is made for the existence of a voltage having a level which is indicative of a back emf in a load circuit immediately following opening of the contacts, and if such a voltage level is detected an incremental adjustment is made in the phase angle at which successive actuations of the contacts are effected. This procedure is repeated under the control of a microprocessor until such time as the voltage which is indicative of back emf reduces to zero, this providing an indication that contact opening is occurring at a time corresponding to zero current crossing in the alternating current waveform.