Abstract: An apparatus for reducing the voltage applied to a load in an AC system utilizes an autotransformer and a relay or equivalent switching device between the common winding and the series winding. In each of the AC lines, the common winding and relay are connected between the load and the AC common while the series winding is connected between the input and the output. The relay is normally open to pass substantially full input voltage to the load, but when closed the relay permits current flow in the common winding to reduce voltage to the load. The relay or equivalent switching is therefore not in the direct flow of load current and can be of lower current rating and smaller size and cost as compared to prior art voltage reduction systems.

Abstract: Voltage dividing circuits which are comprised of capacitors or resistors. In the case of a voltage dividing circuit comprised of capacitors (Fig. 5), the capacitors (C 1 , Cz) are connected each at one end to an output terminal (V out ) and at the other end connected alternately to two power sources (V 1 , V 2 ) through changeover switches (S 1 , Sz). The switches (S 1 , 8 2 ) are selectively operated so that the capacitors (C 1 , Cz) divide a voltage into fractions of that voltage. The average of the fractions of voltage is taken out as an output voltage (V out ). The averaging of the fractions of voltage cancels out the characteristic difference among the capacitors (Ci, C 2 ). The fractions of voltage are changed by varying the time during which each capacitor (C 1 , C 2 ) is connected to either power source (V 1 , V 2 ). In the case of a voltage dividing circuit comprised of resistors (Fig. 12), the resistors divide a voltage into fractions. The average of the fractions of voltage is taken out as an output voltage (V out ). The voltage dividing circuit may employ a method used in known voltage dividing circuits which comprise capacitors or resistors. In this case, the circuit can divide a voltage into smaller fractions of voltage than the known voltage dividing circuits. In other words, the circuit can enhance the resolution of the analog output signal.

Abstract: PURPOSE:To enable to suitably control a generating time by altering the set value of the output voltage of a generator in response to the running state of a vehicle and the load state of a generator. CONSTITUTION:A conduction rate detector 6 sets the terminal (a) to ''1'' level when the average conduction rate of a transistor 41 is lower limit value or lower and the terminal (b) to ''1'' level when it is the upper limit value or higher. A rotating speed variation amount detector 7 sets the terminal (e) to ''1'' level when the variation in the rotating speed of an engine is the prescribed positive value or higher and the terminal (d) to ''1'' level when it is the prescribed negative value or higher. A rotating speed detector 8 oututs a ''1'' level output when the rotating speed becomes the value slightly lower than the rotating speed at the normal running time for the prescribed period or longer. A set voltage generator 5 applies the first set voltage at the normal running time, the second set voltage lower than the first set voltage when the load of the generator 2 is smaller at the abrupt acceleration starting time, and the third set voltage higher than the first set voltage when the load of the generator 2 is large at the decelerating time to a voltage controller 4.

Abstract: Four switching elements are configured to reduce the voltage of either an alternating or a direct current electrical power source The present circuit effectively operates like a variable autotransformer when used with ac input power Additionally, when employed with a conventional resistive load, the present invention exhibits a power factor near unity

Abstract: A voltage controller for use with a fluorescent-lighting system, the controller including a three-phase transformer having three auto-transformer windings each for developing two reduced voltages, three contactors for selectively coupling the full voltage and the reduced voltages to the lighting system, the contactors being switched in closed-transition fashion to avoid power interruptions, and another contactor for opening the winding-neutral connections during voltage switching to avoid shorting the transformer.

Abstract: A variable speed drive for an AC motor has features to reduce the speed of the motor if excess temperature is encountered in the variable speed drive system. The system has a rectifier that converts AC supply voltage into DC voltage on the positive and negative rails. Frequency switches switch the DC voltage to power conductors in a sequence and at a rate to determine the selected frequency. The frequency switches are controlled by a DC demand voltage. A temperature sensor provides an electrical response corresponding to the temperature in the system. The temperature response is compared to a reference voltage, and if it exceeds the reference voltage, the comparator provides an output that draws down the demand voltage by a value corresponding to the difference. Lowering the demand voltage lowers the speed of the motor to allow the system to cool under reduced load conditions.

Abstract: 1. Controlling device for a directly-heated direct-current arc furnace for melting metal, comprising an electrode adjusting device for adjusting the distance between electrode and melt, a static convertor for supplying the electrode with direct current, a current controller the input of which is supplied with the difference between a predeterminable nominal direct-current value and a measured actual direct-current value and the output signal of which is used as a control voltage signal for the static convertor, and comprising a voltage controller the input of which is supplied with the difference between a predeterminable nominal direct-voltage value and a measured actual direct-voltage value and which emits an output signal to the electrode adjusting device, characterized in that the output signal of the current controller is summed with the actual direct-voltage value (Udist ) as pilot control value.

Abstract: An automatic voltage control system controls the voltage delivered to the primary winding (12) of a step-up transformer (10) and hence the power delivered to a dehydrator (40) so as to prevent the step-up transformer (10) from exceeding rated power when a current limit occurs. The automatic voltage control system controls the voltage applied to the primary winding (12) so as to maximize the voltage applied to the grid elements (38) of the dehydrator (40). Upon encountering a current limiting condition, the automatic voltage control system reduces to zero the voltage applied to the primary winding (12) and hence the power applied to grid elements (38) of the dehydrator (40) to dissipate the cause of the current limiting condition. The voltage is reapplied to primary winding 12 at a voltage level below where the current limit occurred. The voltage is then increased to maximize the voltage applied to the grid elements (38) of the dehydrator (40). Upon encountering a voltage limit, the voltage is maintained at a constant level until either an arc or current limit are encountered whereupon the control cycle is repeated.

Abstract: PURPOSE:To improve voltage control accuracy by providing a dead time compensation circuit for correcting the PWM control signal and a DC voltage compensation circuit for correcting a voltage reference in PWN control according to the fluctuation of DC power supply CONSTITUTION:In an inverter for controlling an AC motor 3 through a DC power source 1 and an inverter bridge 2, output VR from a ramp function circuit 5 is divided by an output v18 from a voltage detector 18 and the division result v19 is provided to a voltage reference generator 7 thus producing a reference voltage Vu The reference voltage Vu is then compared with a triangular wave v14 through a comparator 13a thus producing a PWM signal v13a The signal v13a is provided to a dead time compensation circuit 17a in order to compensate for the fluctuation of pulse width caused by the dead time of an inverter bridge, and the output v17a from the compensation circuit 17a is provided to a drive circuit 15 when the influence of the fluctuation of DC power supply and the distortion caused by the dead time are removed in such a manner, a highly accurate controller a can be obtained

Abstract: The DC secondary output voltage of a high voltage switched-type power supply is regulated by automatically increasing or decreasing the amplitude of the primary circuit retrace pulse to compensate for variations in loading imposed on the secondary or output circuit. The automatic regulation is accomplished by the use of a passive saturable reactor coupled in a series with the primary winding of the step-up transformer. The saturable reactor has a saturation characteristic with a relatively low saturation level. Within the saturation limits, the saturable reactor provides a reservoir of energy which can be used to buck the peak voltage pulse applied across the primary, thus controlling the output voltage. The apparatus provides good regulation with minimum number of additional components.

Abstract: The fault protection device is based on a protection circuit in which the presence of the mains voltage is the precondition for the expected protection effect in the event of a fault (transmission of a contact voltage). The disadvantage of the known protection devices (e.g. fault protection devices with amplifiers), that they do not switch off in the case of faults involving an interruption of the centre lead, and the hazardous contact voltage thus remains, is overcome according to the invention in that the lines (2 and 3) leading to the load unit are automatically connected only when the full mains voltage is applied. This through-switching can be effected e.g. by means of two triacs (5 and 6). When the mains voltage is applied and the line has no interruption, only the ignition voltage required for through-switching is then present on a voltage divider (7, 8 and 9).

Abstract: In a television receiver having a picture tube that requires an ultor accelerating potential and an intermediate direct voltage, such as a focus voltage, a high voltage generator is provided that develops the two voltages. A source of alternating voltage is coupled to a primary winding of a transformer for developing an alternating polarity voltage across each of two high voltage secondary windings. A first voltage doubler is coupled to the first high voltage winding for rectifying the alternating polarity voltage developed across the winding during both polarity intervals thereof to produce a first direct voltage. The first direct voltage is applied to an intermediate voltage terminal to generate the picture tube intermediate direct voltage between that terminal and a reference terminal. A second voltage doubler is coupled to the second high voltage winding for rectifying the alternating polarity voltage developed across the winding during both polarity intervals thereof to produce a second direct voltage. The first and second direct voltages are combined and applied to an ultor terminal to generate the picture tube ultor accelerating potential between this terminal and the reference terminal.

Abstract: PURPOSE:To always hold a proper line voltage, by controlling the line voltage of a feeding circuit having different degrees of fast and slow motions of voltage fluctuation by means of a common line voltage controller. CONSTITUTION:The line current has a sudden and quick increase due to a sudden fluctuation of load caused at a feeding circuit 1B, and the output side voltage of a line voltage controller lowers. In such case, a voltage detecting circuit 5 produces a detection signal to start a delaying circuit 6. At the same time, a current relay detect an increase of the line current and immediately transmits a signal to a switching circuit 8. Thus the circuit 8 works to supply the 2nd control signal e2 obtained at an output terminal 7b of a voltage relay 7 to a line voltage controller 2. Accordingly the controller 2 performs a control immediately in case when the circuit 1B has a sudden fluctuation of load to cope with a sudden fluctuation of voltage.

Abstract: PURPOSE:To improve a responsiveness of controlling an output voltage by discriminating the level of a commercial AC power source voltage, storing it, and correcting the output voltage at its starting time of an inverter device at next operating time. CONSTITUTION:When an external frequency command signal applied by a frequency setter 6 is applied to a soft starting circuit 7, an output frequency control signal of its output gradually increases. When it coincides with the external frequency command signal, a comparator 14 for comparing the input signal with the output signal of the circuit 7 stores a bus voltage signal from a DC bus voltage detector 15. The stored voltage is transmitted instantaneously as a power voltage information signal to an output voltage controller 11 by the comparator 14 when the setter 6 generates an external frequency command signal, and the output voltage of an inverter device is corrected by rapidly correcting the output signal of the controller 11.

Abstract: PURPOSE:To enable to shorten the wasteful switching time irrespective of load characteristics by increasing the gain of a current controller when a converter is switched in a speed controlling circuit having both positive and negative direction converters. CONSTITUTION:A current controlling loop having a sequential current controller 9 and a voltage controlling loop having a voltage controller 13 are provided within the speed controlling loop of the speed controlling circuit of a DC motor 2 having a positive side converter 3 and a negative side converter 4 connected in antiparallel to one another, and the gate pulse generator 17 of the converter and a normal and reverse switching logic circuit 18 are controlled by the output of the controller 13. A zero current detector 25 is provided in the current controlling loop, the zero time point of a main circuit current is detected when the positive and negative converters are switched, while the gain of the current controller 9 is increased in accordance with the detection signal, and the wasteful switching time can be shortened.

Abstract: The control circuit changes over (during starting in a frequency range from zero to a given variable limit) from voltage control supported by current control to purely current control, the voltage controller being disconnected. The current amplitude occurring during starting is set between a maximum and zero. The rate at which the frequency changes during starting is also controlled. Whenever the frequency limit is reached a check is made to see whether the machine's speed is following the given frequency or whether the machine has become asynchronous in which case the frequency is reset to zero and the machine restarted.

Abstract: PURPOSE:To prevent a controller from being subjected to malfunction by preventing the drop of voltage applied to the controller of an internal-combustion engine at the starting of said engine. CONSTITUTION:A control circuit power supply switch 11 is provided between a battery 3 and a regulator 5 for voltage drop, and the voltage dropped by this regulator 5 is applied to the microcomputer 12 of a controller 10 via a reverse- current preventing diode 6 and a backup condenser 7. Further, a non-lock type starting switch 8 is provided on the later stage of the controller power supply switch 11, and connected to the microcomputer 12. The backup condenser 7 having large capacity is charged to a controller driving voltage value through the reverse-current preventing diode 6 until an on-signal is issued from the microcomputer 12 via a relay circuit 13 to a cell motor 2 after turning the control power supply switch 11 on, so that it is possible to obtain a larger voltage value than that capable of driving the controller.

Abstract: PURPOSE: To set the DC side voltage of a PWM converter to the diode rectified voltage or lower of an AC power source voltage by controlling the phase of an AC input current so as to become in delay phase to the AC power source voltage CONSTITUTION: When a converter 1 performs a forward conversion, the AC input current I leads in phase at an angle ϕ to the AC power source voltage E Since the voltage deviation signal ΔV is however negative polarity, the current command signal IP becomes reverse phase to a phase shift sinusoidal wave signal SE In case of the reverse conversion, the AC input current I becomes delayed phase by (π-ϕ) to the AC current voltage As a result, the magnitude of the AC input voltage V can be reduced from the diode rectified voltage of the AC power source voltage E even in case of any of the forward conversion and reverse conversion of the PWM converter 1 Accordingly, the DC output voltage of the converter 1 may be set to the voltage required for the load COPYRIGHT: (C)1983,JPO&Japio

Abstract: PURPOSE:To safely and rapidly stop a motor at its stalling time by stopping a variable frequency power source when the output of a reference circuit which produces a control output based on the deviation between a reference signal and a detection signal continues longer than the prescribed period of time at the set value. CONSTITUTION:A converter 2 which converts AC to DC and an inverter 5 which converts the DC to the prescribed frequency are controlled with a voltage reference signal VREF form an oblique signal generator 8 connected to a speed setting unit 7, a voltage detection signal VS from a voltage sensor 10 and a current detection signal from a current sensor 14 as references. A voltage controller 9 outputs a deviation between the VREF and FS, and it becomes VREF>VS when the motor 6 is stalled. Accordingly, the output of an amplifier 19 is raised. The output of the amplifier 19 is compared with a limiting value from a setting unit 25, and when it exceeds the limiting value, a transistor 31 is conducted ON, and a time relay 32 starts operating, and after the prescribed period of time, the contact of the relay 32 is operated to interrupt the power source 1 or to stop the converter.

Abstract: PURPOSE:To stably operate a current type inverter even under low speed operating condition by rectifying the output voltage of an inverter circuit by an amplifier having an absolute value converting function and producing an output of a voltage detector through a gate which is opened or closed in synchronization with a commutation control signal. CONSTITUTION:The output voltage of an inverter 15 is detected by a voltage detector 27, compared by a comparator 25 with a reference signal of an input limiter 26, and supplied to a voltage controller 20. The output of the controller 20 is compared by a comparator 21 with the output of a current detector 17, and a power reactor rectifier 13 is phase-controlled. The detector 27 has rectifiers 61-63 having absolute value converting function, and can effectively detect the output voltage even when the operating speed is low. The outputs VF of the rectifiers 61-63 are driven by the rectifying frequency 6f, and a pass signal TF corresponding to the commutation superposition time can be obtained from the output of one short multivibrator 65 driven by the frequency 6f, and outputted through a gate 66 by a signal TF. In this manner, the output signal VF1, from which commutation surge voltage is removed, can be obtained.

Abstract: A warning feature for a high voltage controller or the like. A lamp is mounted on the controller cabinet, and connected to an interlock circuit so as to be illuminated whenever line voltage is being supplied to a contactor assembly, regardless of the open or closed status of the contactor itself.

Abstract: PURPOSE:To dissolve unbalance of output voltages of a polyphase inverter to an unbalance load by a method wherein output currents are detected at every phase, and the IR compensations are performed respectively. CONSTITUTION:The output voltages of the inverter 1 are detected by a transformer 2 and a voltage detecting circuit 3, and the voltages between respective phases are averaged. A DC voltage proportional to this averaged value is check as a feed back signal VF to form the difference 6 between the reference voltage VR and is inputted as a control signal to a computing element 13. The computing element 13 adds this voltage control signal and a voltage compensating signal of each phase at every phase, and the result is inputted to a control circuit 9 through an A/D converter 8. A clock signal generating part 10 puts out a clock signal to close an analog switch 12U of U phase at timing to decide an igniting signal of U phase to send a feed back signal being added with an IR compensating signal proportional to a current flowing in U phase to the A/D converter 8. Accordingly, IR compensation for each phase can be performed, and unbalance of the output voltages to the unbalance load can be dissolved.

Abstract: A servosystem for controlling the voltage in X-ray generators includes a system for controlling the voltage of the primary of a high voltage transformer for feeding the X-ray tubes. A servosystem controls the position and adjustment of acceleration, uniform movement and braking, and supplies a direct current motor, of the permanent magnet type and of standard manufacture, which moves the brushes of a three-phase or mono-phase toroidal autotransformer, the operation of which fixes the primary voltage of the high voltage transformer which, in turn, supplies a voltage to an X-ray tube.

Abstract: PURPOSE:To improve the readhesive characteristics of an induction motor type electric motor vehicle by composing to divergently vibrate the slipping speed of the vehicle when the vehicle slips. CONSTITUTION:A frequency controller 34 receives a frequency command fM obtained adding or subtracting a slip frequency fs and or from a vehicle speed signal fG detected by a tachometer generator 32 connected to a driven wheel 31, and a voltage controller 38 receives a deviation between a voltage command VR proportional to the frequency command fM and the output voltage VM of an inverter. When wheels 28 slip, the frequency of the motor 24 decreases to reduce a current, thereby decreasing the voltage drops of impedance elements 12-14. Since the output voltage of the inverter 11, however, does not almost alter, the voltage applied to the motor 14 is raised. In this manner, the apparent time constant of the generated torque of the motor is increased with respect to the abrupt decrease of the slip frequency, thereby divergently vibrate the slipping speed of the wheels 28.

Abstract: PURPOSE:To simplify constitution of a voltage controller by applying a signal with a required magnitude to a deviation signal of a negative feedback type electrometer detecting electrostatic latent image potential in a white ground part of a manuscript and by using an output of the electrometer as development bias voltage. CONSTITUTION:Deviation electrostatic latent image potential taking, as reference, potential by an electric field fluctuation device C corresponding to a manuscript white ground part of a photosensitive drum 1 is detected with an electric field voltage converter A of a probe P of a negative feedback type potentiometer further in response to this deviation electric potential, high voltage of a high voltage power source HT is applied to voltage detected by a synchronous detector C of a main body part MB by a high voltage controlling circuit E, allowing the potentiometer NFEM to be controlled with negative feedback. Accordingly when an output of the potentiometer NFEM is applied as developing bath voltage to a development electrode 2a of a developing device 2, development bias voltage control stable over a long period is performed with simple constitution that uses the electrometer and a high voltage source for a development bias together. Further also when a signal with required polarity or a phase is applied to the deviation signal, the same can be done.

Abstract: The precipitator system includes a voltage controller which produces from an alternating power source a variable output. This variable output drives a high voltage converter which applies a high voltage to a precipitator. This variable output is controlled by a control signal from a command subsystem. Preferably, the command subsystem is operative to repress the drive to the high voltage converter in response to its loading exceeding a predetermined limit during a corresponding limit interval. After this limit interval, the command subsystem is operative to rapidly restore productive drive to the high voltage converter, preferably by the next half cycle of the power source that has a polarity opposite to that existing at the beginning of the limit interval. In this fashion stabilized operation is quickly achieved. Also included, preferably, is a conductive element that is coupled to the high voltage converter.

Abstract: PURPOSE:To prevent a DC circuit including a main motor from becoming an overcurrent state by reducing the output of a field power source when an electric motor vehicle passes an AC-AC section during a regenerating operation. CONSTITUTION:A main circuit voltage controller 9 and a field voltage controller 23 input a command signal from a master controller 8 and respectively control a thyristor power source 5 and a field thyristor power source 21. When a vehicle element 11 detects a signal from a ground element 12 installed before an AC-AC section SE while an electric motor vehicle carries out a regenerating operation, the controller 9 controls the phase shift to the degree not fail the commutation of the thyristor of the power source 5, and the controller 23 cuts the output of the power source 21, thereby setting the field current to zero. When a vehicle element 11 detects a signal from a ground element 26 installed at the rear of the section SE, the regenerating operations again carried out.

Abstract: PURPOSE:To prevent overload due to the variety of loads, by calculating average output power corresponding to conduction time for every period of power supply for comparison thereof with allowable average power to decrease the output voltage of a generator CONSTITUTION:The voltage, current and power of an AC generator 1 supplying pulse power to the load 16, nuclear fusion equipment, etc are detected by detectors 11, 12, 13 to input into the monitor controlling device 17 for the control of the field winding 6 of the generator 1 via a voltage controller 10 and thyristor rectifier 7 by the output thereof Besides, the monitor controlling device 17 is constituted of a process input-output unit 171, arithmetic control unit 172 and in put-output 173 to calculate average output power for every period of power supply with the generation of output by comparing with allowable average power Therefore, the varieties of loads and operating patterns produce no over load in the generator 1 to effectively apply the capacity thereof