Abstract: This invention proposes an operating control device and method for a winding type induction machine that ensures that the harmonic components naturally present in the primary voltage of a winding type induction machine, do not correspond to the antiresonance point of the impedance characteristic of the transmission system to which the winding type induction machine is connected. Those corresponding harmonic components are eliminated from the primary winding of the winding type induction machine by applying appropriate voltage command values to a PWM controlled inverter if there is distortion of the primary voltage or if the transmission system is being changed over.

Abstract: An induction system of the invention is adapted to apply coordinate transformation to the excitation current reference vector corresponding to the primary interlinkage magnetic flux vector reference value and the primary current vector so that they exist in the same coordinate system, thereafter to control the secondary current vector so that the primary interlinkage magnetic flux vector is in correspondence with the primary interlinkage magnetic flux vector, thereby allowing the primary side of the wound-rotor induction machine to function apparently as a voltage source.

Abstract: A reactive power compensation apparatus for compensating for voltage fluctuation of an AC power supply system includes a first arithmetic circuit for synthesizing a positive-phase fundamental wave voltage signal from voltages of the AC power supply system, a second arithmetic circuit for synthesizing negative-phase voltage signals from the voltages of the AC power supply system, a third arithmetic circuit, coupled to the first and second arithmetic circuits, for synthesizing current instructions from the positive-phase fundamental wave voltage and the negative-phase voltage signals, and a circuit, coupled to the third arithmetic circuit, for generating a reactive power corresponding to the current instructions.

Abstract: In a reactive power compensation apparatus for compensating reactive power generated by a load connected to an AC power supply system, dual phase current signals obtained by dual phase-converting the load currents and unit dual phase voltage signals synchronized with voltages of an AC main line connected to the load are used, and arithmetic operations thereof are performed to separately detect an in-phase reactive component signal and opposite phase component signals of the load currents. Current commands are generated on the basis of the separately detected signals, thereby controlling the reactive power compensation apparatus on the basis of the current commands.

Abstract: A frequency converter apparatus is provided with a frequency converter coupled to an AC power supply and to a load. The frequency converter converts an AC input with a given input frequency into an AC output with a given output frequency. The frequency converter apparatus is further provided with a frequency reference circuit and a harmonic cancel circuit. The frequency reference circuit supplies a reference signal to the frequency converter so that the output frequency of the AC output follows the reference signal. The harmonic cancel circuit supplies a harmonic cancelling signal to the frequency reference circuit so that the prescribed order of the higher harmonic of the AC output is substantially cancelled according to the frequency, magnitude and phase of the harmonic cancelling signal.

Abstract: In an AC current control system for controlling multi-phase AC currents supplied from a power converter to a load, the currents are detected and coordinate-transformed into orthogonal two-axis current values i.sub.d, i.sub.q in a rotating coordinate rotating at an angular frequency .omega., and then compared with the references. The deviations are used to determine two-axis voltage values e.sub.d *, e.sub.q *, which are coordinate-transformed into multi-phase voltage values determining the output voltages of the power converter. The system is characterized in that the voltage value e.sub.d * is determined not only from .DELTA.i.sub.d but also from the product of .omega. and .DELTA.i.sub.q, while the voltage value e.sub.q * is determined not only from .DELTA.i.sub.q but also from the product of .omega. and .DELTA.i.sub.d. This arrangement makes it possible to provide a voltage component corresponding to the voltage drop across the inductive component of the load which is 90.degree. in advance of the current.

Abstract: A current control apparatus includes an instructor for providing a DC amplitude instruction and an AC phase instruction, and a cycloconverter for supplying an induction motor with AC load currents. These load currents are detected by sensors. The sensed signals from the sensors are applied to a detector. The detector generates a DC phase error signal and a DC amplitude signal according to the load currents and the phase instruction. The amplitude instruction, amplitude signal and phase error signal are applied to a comparator circuit. The comparator circuit generates a first voltage instruction and a second voltage instruction. These first and second voltage instructions are applied to a control circuit. The control circuit supplies the cycloconverter with voltage instructions. The comparator circuit, control circuit, cycloconverter, sensors and detector constitute a closed DC feedback control loop which utilizes a vector control method.

Abstract: In an inverter apparatus including a plurality of parallel branch circuits connected across a D.C. source, each including a pair of serially connected controllable switching elements, and a plurality of semiconductor elements connected in parallel opposition with respective switching elements, a D.C. reactor is connected on the D.C. side or A.C. side of the inverter and a circuit is connected across the D.C. reactor for preventing attenuation of the current flowing through the D.C. reactor during the OFF period of the switching elements. A source of control pulses is provided for rendering ON respective controllable switching elements each for a 120.degree. interval of the output alternating current. The source of control pulse includes means for chopping the current flowing through each controllable switching element at a predetermined modulation frequency for the former or latter 60.degree. of the 120.degree. interval.

Abstract: In a method and apparatus for controlling the speed of an induction motor energized from a source of variable frequency, e.g. a controllable inverter, a control signal which is a function of the primary current of the induction motor is produced, a predetermined slip frequency pattern signal is generated in accordance with the control signal, and the source is controlled in accordance with the slip frequency pattern signal for controlling the operating frequency. By suitably determining the shape of the slip frequency pattern signal it is possible to operate the induction motor with either one of normal induction motor characteristic, DC series motor characteristic, DC shunt motor characteristic, DC weak field motor characteristic and DC compound motor characteristic, and to operate the induction motor for smooth and continuous power regeneration.