Abstract:
Systems and methods for operating a variable speed drive to receive an input AC power at a fixed AC input voltage and frequency and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter stage to convert the input AC voltage to a boosted DC voltage, a DC link connected to the converter stage to filter and store the boosted DC voltage from the converter stage; and an inverter stage to convert the boosted DC voltage into AC power with variable voltage and the variable frequency. An integral bypass contactor is connected in parallel with the VSD between the AC power source and the AC output power. The integral bypass contactor is arranged to bypass the VSD when the VSD output frequency and voltage are approximately equal with the AC input voltage and frequency.
Abstract:
A refrigerator and a method of operating the same are disclosed. In the refrigerator and the method of operating the same, a voltage of an electric power input is measured and rectified through the half wave rectification or the full wave rectification in correspondence with the measured voltage, so that the refrigerator can be used without a voltage converting device when a voltage of the input power is changed. Therefore, the change or the modification of the circuit is not needed in order to use the refrigerator in other regions. Since components are compatible and utility of the components is improved, manufacturing costs can be reduced.
Abstract:
A self-excited induction motor variable speed drive using a known self-excitation method in which a capacitor is connected in parallel with the motor. Power is supplied by a supply convertor, a D.C. link and a motor convertor, the latter running at the motor frequency. The motor convertor includes a current bypass switching circuit comprising a capacitor bank connected to the motor terminals and to a neutral point between a pair of thyristors connected across the D.C. link.
Abstract:
The invention relates to a method and a control device (13) for regulating a drive device (1) which comprises an electric motor (5) with a motor shaft (7) and a converter (11) for supplying power to the electric motor (5). To this end, measured values of measured variables, which characterize a power loss of the drive device (1), are detected and a converter output voltage is adjusted depending on the detected measured values in such a way that the power loss decreases.
Abstract:
Die Erfindung betrifft ein Verfahren zum Stabilisieren einer elektrischen Spannung (U1,U2) in einem Zwischenkreis (16), in welchen von Einspeiseeinrichtung (12) eine gleichgerichtete Spannung aus einem elektrischen Versorgungsnetz (14) eingespeist und an welchem ein elektrischer Verbraucher (18,20) betrieben wird. Das Verfahren umfasst die Schritte: Verbinden eines elektrischen Energiespeichers (46, 52) über eine steuerbare Schalteinrichtung (42,48) mit dem Zwischenkreis (16), Ermitteln eines Spannungssignals zu der elektrischen Spannung (U1,U2) des Zwischenkreises (16) durch eine Regelungseinrichtung (44,50), Erzeugen eines Steuersignals (S1,S2) für die Schalteinrichtung (42,48) in Abhängigkeit von dem ermittelten Spannungssignal durch die Regelungseinrichtung (44,50) und hierdurch Steuern eines Energieaustauschs zwischen dem Zwischenkreis (16) und dem Energiespeicher (46,52).
Abstract:
The invention relates to a method for reducing load-rejecting overvoltages when operating a synchronous rectifier (29) for a multiphase alternating current having a number of inputs (60.1 to 60.5) corresponding to the number of alternating current phases (A through E) of the alternating current, and at least two outputs for providing a direct current, wherein one alternating current phase (A through E) is connected to each input (60.1 to 60.5) and each of the inputs (60.1 through 60.5) can be electrically selectively connected to either the first (B+) or the second (B-) output (using active switching elements such as MOSFETs oe IGBTs according to the requirements of control means.
Abstract:
Phase correction unit (25) for outputting a commutation signal for switching a winding that allows a current to flow to brushless DC motor (4) and drive unit (16) for outputting a drive signal indicating supplying timing of electric power supplied to brushless DC motor (4) by inverter (3) based on the commutation signal output from phase correction unit (25) are provided so as to maintain a predetermined relation between a phase of a current flowing to a predetermined winding of brushless DC motor (4) and a phase of a voltage. Since brushless DC motor (4) is driven by a signal for holding the predetermined relation between the phase of the current and the phase of the voltage, the stability of drive under high-speed and high-load conditions is enhanced and a drive range is extended.
Abstract:
The invention presents a control arrangement of an electric motor (2) used with a frequency converter (1 ) as well as a method for controlling an electric motor used with a frequency converter. In the invention the frequency converter is fitted between the power source (3) and the electric motor (2). A rectifier (5, 18) that transmits the braking power of the motor is fitted to the intermediate circuit (8, 9) of the frequency converter. In the method according to the invention the intermediate circuit voltage (21) is regulated with a control (11) of the braking power according to the reference value (12) of intermediate circuit voltage.