摘要:
In the control of a synchronous motor driven by a power converter of voltage source type, the phase of the current flowing into the motor is detected and gate signals are produced on the basis of the phase of the current, so that the output frequency of the power converter is controlled by the gate signals so as to control the motor.
摘要:
A method and an apparatus for controlling the operation of the synchronous motor are disclosed in which the synchronous motor is started with a starting power supply and operated with a steadying power supply. The starting power supply is adapted to alternately repeat acceleration and deceleration of the synchronous motor in the neighborhood of the frequency thereby to bring the synchronous motor into the point where the synchronous motor is in synchronism with the steadying power supply. The starting power supply comprises a current control circuit and a phase angle control circuit, which circuits control the motor current in such a manner as to prevent the voltage drop due to the synchronous reactance of the motor from exceeding the induced voltage of the motor, while at the same time controlling the power factor angle to be in the range from a lead 90.degree. to the angle corresponding to a maximum output point produced by said motor current.
摘要:
Shortcircuit in an arm including a series connection of GTO's and reactors of an inverter is detected by sensing a voltage across the reactor. In one method, the shortcircuit in the arm is detected when voltages are coincidently applied to a P-line arm reactor and an N-line arm reactor for a predetermined time period. In another method, it is detected when an integrated value of a voltage across at least one of the reactors exceeds a predetermined level.
摘要:
A pulse width modulation inverter in which a staircase wave signal is used as the modulating wave. The number M of the stair steps of the staircase wave signal is set at a given integer in a range defined by 2.ltoreq.M.ltoreq.(N-3)/2 where N represents the number of the carrier waves appearing during a half period of the staircase wave and an odd integer not smaller than 7.
摘要:
An induction motor is operated by a power supply of variable voltage and variable frequency. The voltage and frequency of the variable-voltage variable-frequency power supply is changed by a control circuit to accelerate or decelerate the induction motor. For slowly controlling the speed of the induction motor, the ratio of the output voltage to the output frequency of the variable-voltage variable-frequency power supply is maintained substantially constant. The control circuit includes a voltage correcting means which, in response to a command for sudden acceleration or deceleration of the speed of the motor, corrects the output voltage of the power supply in accordance with the acceleration or deceleration rate and the prevailing magnitude of the output frequency of the variable-voltage variable-frequency power supply.
摘要:
A current source inverter circuit having a plurality of branches, each branch consisting of a pair of thyristors adapted to be switched on alternatingly for power supply from a D. C. power source and diodes connected in series to the thyristors. To each connection point between a thyristor and a diode, there is connected one end of one of a plurality of commutating capacitors, while the other ends of the capacitors are connected in common. An auxiliary charging source is provided between the common connection of the commutating capacitors and one of the terminals of the D. C. source for performing an auxiliary charging for each commutating capacitor through a respective thyristor. Between one of the terminals of the D. C. power source and the common connection of the commutating capacitors, a series circuit consisting of a diode and an auxiliary D. C. source is provided constituting a by-pass for the charging voltage of the commutating capacitor when the associated thyristor is in the ON state.
摘要:
A control circuit for a semiconductor element with a control electrode includes a signal transmission circuit, in which two switching elements made conductive when a control signal is supplied from a control signal source to the switching elements through a signal insulating element, are provided so that the control signal is transferred to a turn-on circuit for the semiconductor element only when the switching elements are simultaneously made conductive.
摘要:
A gate circuit for gate turn-off thyristors is disclosed which includes a turn-on circuit formed of a series combination of a turn-on power source and an NPN transistor and a turn-off circuit formed of a series combination of a turn-off power source and a thyristor, and in which a PNP transistor is provided between the anode and gate of the thyristor in such a manner that the base of the NPN transistor and the base of the PNP transistor are connected to each other and a junction of these bases receives a control signal for turning on or off a gate turn-off thyristor.
摘要:
When a power conversion apparatus such as inverter or chopper comprises gate turn-off thyristors (GTO's), current limiting reactors are connected to cathodes of the GTO's and opposite ends of each of the reactors are connected to positive and negative terminals, respectively, of a gate power supply which supplies a turn-on current and a turn-off current to the respective GTO. With this arrangement, an energy stored in each of the reactors at the turn-off of the GTO is absorbed by the gate power supply.
摘要:
A control device for a pulse-width modulated inverter comprises means for generating as a carrier wave a triangular wave synchronizing with an AC output from the inverter, means for generating as a modulating wave a train of rectangular wave pulses which synchronize with the triangular wave and have a width corresponding to a section effective for a modulating operation and a predetermined amplitude, voltage level setting means for setting the amplitude of the train of rectangular wave pulses, and means for modulating the triangular wave with the train of rectangular wave pulses and generating a control pulse for the AC output. The rectangular wave pulses are so set as to have a modulating level of zero in the proximity of a point corresponding to the zero point of the AC output of each phase thereby to remove a frequency divider for adjusting input frequencies of the triangular wave generating means and the modulating wave generating means and to prevent a useless modulating operation leading only to an increase in the number of commutations of the inverter.