Abstract: PURPOSE:To eliminate irregular rotation and unstability at a low speed by constantly controlling a DC voltage in PWM mode in low speed range of several 10% of speed at several 10% and controlling it in PAM mode over several 10%. CONSTITUTION:A PWM modulator 17 controls PWM according to a command value S3 with the reference output S1 of a speed reference circuit 15 being 0-30%, thereby controlling an inverter transistor 5 ON or OFF by a base drive circuit 16. The output S5 of the modulator 17 becomes constant value between 30 and 100% of the reference output S1, instead a voltage pattern generator 13 outputs as a command value an output S2 proportional to the reference output S1, controls a voltage control circuit 11 in response to the output the difference from the DC voltage detected by a DC voltage sensor 12, thereby controlling the DC output voltage of a thyristor 2 equal to the command value V1.

Abstract: A variation of an old but neglected pulse shaping technique, raised-cosine, is investigated. By overlapping raised-cosine pulses in each of two data streams and then by quadrature combining them, a simple QPSK/MSK type modulation results. This quadrature overlapped raised-cosine (QORC) modulation exhibits a hybrid structure of QPSK and MSK modulations. The power spectral density of QORC is shown to take on the form of the product of the power spectral densities of MSK and QPSK. The obvious consequences are that the power spectral density main lobe retains the width of the spectral density main lobe of QPSK, but the sidelobes drop off much faster (1/f^{6}) . A simple QORC modulator can be implemented similar to an MSK modulator. Several correlation type receivers are investigated and their performances calculated. Computer simulation results are used to compare end-to-end system performance of QORC and staggered QORC (SQORC) with MSK, QPSK, and staggered QPSK (SQPSK) for both linear and nonlinear satellite channels. The performance of QORC and SQORC compares very favorably with QPSK, SQPSK, and MSK. QORC performs particularly well in the presence of a nonlinear channel. The effect of phase equalization of the channel filter was investigated with outstanding performance improvement. The simulation results show that sidelobe regeneration caused by the channel nonlinearity is much less for SQORC than it is for the other modulation formats considered.

Abstract: A transistor is operated in the PWM mode such that a hlaf sine wave of current is delivered first to one-half of a distribution transformer and then the other as determined by steering thyristors operated at the fundamental sinusoidal frequency Power to the transistor is supplied by a dc source such as a solar array and the power is converted such that a sinusoidal current is injected into a utility at near unity power factor

Abstract: We report the generation of picosecond pulses by the direct modulation of a buried heterostructure GaAlAs diode laser. Pulse width of 28 ps is achieved at a repetition frequency of 2.5 GHz. Pulse width dependence on the experimental parameters is described.

Abstract: An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin θ, where θ is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120° at the stator frequency. Switching control commands for electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a "flyback" DC-DC converter circuit for recharging the battery.

Abstract: A method for operating an electrostatic precipitator with a DC voltage and superimposed pulses or superimposed AC voltage in which individual parameters such as amplitudes, pulse repetition frequency, pulse width, etc. are iteratively and continuously varied in such a manner that the sum of the pulse and the DC voltage power approaches a minimum. A computer which calculates, from the dust load and the absorbed electric energies of the filter, control commands for the DC and pulse voltage source is used for this purpose.

Abstract: To control the operation of an actuator motor (48) an input signal is compared with a feedback signal at a summing junction (22) with the resultant error signal used to bias off the output of a sawtooth generator (30) by pulse width modulation in a modulator (28). The pulse width modulated signal and three commutation signals from an optical detector (34) are input to a commutation circuit (32) that decodes the input by means of a programmed read only memory into a six state drive voltage that is applied to optical isolators (36), (40) and (44). Two of the six states from the commutation circuit (32) are input to each optical isolator that provides an output for driving a power stage. The optical isolator (36) drives a power stage (38), the optical isolator (40) drives a power stage (42) and the optical isolator (44) drives a power stage (46). Each of the power stages has an output connected to one motor lead for the delta wound motor (48) that includes velocity limit protectors (76) through (78). Commutation signals to the commutation circuit (32) are provided by the optical detector (34) that responds to the rotation of a commutation disc (102). Rotation of the rotor (54) of the motor (48) is gear coupled to a feedback potentiometer (62) having an output coupled through a compensating lead/lag network (64) to be compared with the input signal.

Abstract: A fully implantable programmable cardiac pacer includes two main pacing channels driven by a crystal oscillator circuit. For each channel, amplitude and pulse width are programmed in paired combinations corresponding to monotonically increasing charge density. Selectively combinable constant current sources are shared by each channel. A low battery indicator system samples battery voltage relative to two threshold levels. In magnet rate, if the main battery voltage is above the first threshold, the fixed pacer output will be 70 beats per minute. If the battery voltage is between the first and second threshold levels, the fixed pacer output will be 62.5 beats per minute. An emergency RC oscillator continuously produces an output at 52.5 beats per minute and one millisecond pulse width. The emergency output is switched directly to the output of channel 2 when either the low battery voltage falls below the second threshold or the crystal oscillator frequency changes when tested by a frequency checking circuit using the output of the RC oscillator as a reference clock. An emergency battery is coupled to the main battery via a diode steering circuit which allows the remaining capacity to be combined with that of the emergency battery.

Abstract: In this paper the extension of the subharmonic method for pulse-width modulation (PWM) systems, in the case in which the ratio between modulating and carrier wave amplitudes can be varied from 0 to ?, is studied in an analytical way. This method allows us to obtain an inverter output waveform variable continuously from a nearly sinusoidal to a square wave and to increase somewhat the amplitude of the fundamental output wave without a significant worsening of the harmonic content, a feature particularly useful for drives with wide speed variations or which need an optimized use of dc power supply.

Abstract: An energy conserving drive circuit is provided for switched mode power converters having a transformer with primary current controlled by a main power switch whose conduction is in turn controlled by a pulse width modulator. Transformer leakage inductance energy is applied to drive the pulse width modulator and the main power switch in a run mode after start-up. The drive circuit includes an improved non-dissipative snubber network which supplies the drive power for the main power switch and which also disables a start-up circuit.

Abstract: Regulation of inverter-machine drive system torque and frequency in accordance with operator commands is achieved by the use of an improved, microcomputer-based, control apparatus. At machine frequencies less than a preselected machine frequency, inverter pulse width modulation signal pulses and half cycle polarity signal pulses are supplied by the control apparatus to the inverter to regulate the duration and conduction sequence, respectively, of inverter switching devices in accordance with pulse width modulation signal data computed by equilateral triangulation and stored half cycle polarity signal data. At frequencies above the preselected machine frequency, when computation of inverter pulse width modulation signal data becomes impractical, inverter pulse width modulation signal pulses are synthesized from stored data. This achieves simplification of control hardware and provides improved machine drive system performance.

Abstract: Method and apparatus for evenly distributing the switching duty among power transistors in a full bridge inverter controlled by current band PWM, by switching first the top half of the bridge and then the lower half of the bridge to shape the output current waveform.

Abstract: Ground control system for use with a spreader of dry bulk material at a predetermined rate and speed. The spreader mounts on a vehicle or like structure. The ground control system has input variables of travel rate of the vehicle and conveyor rate of the conveyor running through the spreader, and an output signal for controlling height of a feedgate movable at an exit port of the spreader. The travel rate input signal includes sensing the speed of the vehicle and accounts for calibration signals dependent on vehicle components such as tire sizes and other constants, and includes variable inputs such as the swath width and the application rate of spreading. The conveyor speed input signal includes the speed of the conveyor, predetermined constants such as conveyor width, gear ratio, etc., and input variables including the density of the material and the weight of the material. The input signals are differentiated for controlling the servo coupled to the feedgate. A feedback signal from the feedgate connects to the conveyor input circuit. The servo control signal to the feedgate can be pulse modulated for optimum control of the opening and closing speed of the feedgate. The pulse rate of the pulse modulation can also be adjustable. The system provides for the saving of energy.

Abstract: A programmable cardiac pacemaker pulse generator utilizing digital circuitry for controlling the provision of cardiac stimulating pulses. The pulse generator is capable of having the rate, the pulse width, the pulse amplitude, the refractory period, the sensitivity and the mode of operation programmed. In addition, the pulse generator can have the output inhibited and can respond to programming signals causing a threshold margin test to be performed, effects of closure of the reed switch overridden, a hysteresis function added and a high rate exceeding the normal upper rate limit programmed. Many of the programmable functions of the pulse generator can either be programmed on a permanent or a temporary basis. The pulse generator further includes means for signaling the acceptance of a programming signal, and means to reset the program acceptance circuit if extraneous signals are detected as programming signals. The program signal acceptance circuit performs several different checks on the detected programming signal including a parity check, an access code check and determining if the proper number of signals were transmitted within a given time. The timing circuit of the pulse generator includes a crystal clock oscillator and counter means for counting the clock pulses therefrom to determine the rate of the pacemaker. The pulse width of each pacemaker pulse is determined by using a voltage controlled oscillator in place of the crystal oscillator to obtain energy compensation due to the battery voltage decreasing with time.

Abstract: The maximum output voltage obtainable from a pulse-width modulated inverter is less than that obtained when the inverter output waveform is a square wave of wanted frequency. Therefore, in order to realise the full potential of the inverter it is necessary to make the transition from a PWM output waveform to a square wave. Due to the practical limitations of the power circuit, it is not possible to reduce the width of unwanted pulses in the PWM waveform gradually to zero, but instead, pulses of a finite width must be dropped abruptly from the waveform. This results in step changes in the output voltage which can produce large current transients in the power circuit and the load. It is shown that the traditional method of pulse dropping is unsatisfactory and a new method is proposed which produces much smaller step changes in output voltage.

Abstract: An intensity control for fluorescent lamps of the type wherein a triac in series with the lamp provides control of the lamp current. Triac gating is controlled by a novel phase-lock circuit. In the phase-lock circuit, voltage squaring means are provided for producing unipolar square waves having a pulse width equal to a corresponding half cycle of the a.c. input power. Ramp waves generated from the square waves are applied to the base of a PNP transistor. Current through the lamp is sampled and produces a proportional voltage signal which is superimposed on a parallel path of the square waves to create a phase reference signal. An intensity control potentiometer supplies a selectable d.c. intensity control signal of polarity opposite the phase reference signal, and the intensity control signal and phase reference signal are algebraically added together. The resultant signals apply to the inverting input of integrating amplifier which reverses the polarity and integrates the resultant signal. The integrated signal is also connected to the base of the PNP transistor. The PNP transistor conducts when the combined voltage of the ramp signals and integrated signals fall below zero potential. When the transistor conducts, a circuit is completed supplying a control signal to the gate of the triac.

Abstract: An amplitude ratio KH of a specific level of a modulating wave and a crest value of a carrier wave is introduced into control of a pulse width modulated inverter, and a desired pulse width modulating signal is calculated by a microcomputer, using the amplitude ratio KH as a control variable

Abstract: Sinusoidal excitation currents are supplied to the three terminals of a "wye" or "delta" connected three phase motor by an improved multiphase motor energizing drive system. For each terminal associated with a different phase, an individual feedback signal representing the current flowing into that respective terminal is sensed and subtracted from its corresponding controllable sine wave reference command to produce a current error signal for each terminal. The error signal for each of these currents is preferably converted to a two-state signal by means of an associated pulse width modulator. The modulator outputs are used to control power semiconductor switches which connect the corresponding motor terminal to either the positive or negative dc voltage. In the preferred system, for one of the terminals, the associated current feedback loop and reference command are omitted, and the associated pulse width modulator is driven by the inverted sum of the error signals from the other two phases. The result is inherently balanced multiphase excitation currents into the motor terminals.

Abstract: PURPOSE:To enable making of a recording picture uniform in concentration, by a method wherein a voltage applied to a heating resistor is detected, and a width of a pulse applied to the heating resistor corresponding to the voltage is caused to change. CONSTITUTION:Pulse voltages 3 and 4, generated from a pulse generator 2, are applied to a voltage control oscillator 7 where the voltages are sampled and held at a rise point of time of their respective pulse voltages and an oscillating frequency is caused to change based on a voltage value. A frequency divider 8 divides the oscillating frequency appropriately to produce a pulse signal having a given pulse width. For example, if only a slight part of a heating substance of a head is energized, a voltage of a 15V output of a constant-voltage power source 9 hardly drops and is applied to the heating resistor, and an oscillator 7 oscillates at 20kHz to produce a pulse of 0.5msec by means of the frequency divider 8. On the contrary, if a group of the heating resistors is totally energized and the output voltage of the power source 9 decreases to 11V, the oscillator 7 oscillates at 10kHz to produce a pulse width of 1.0msec by means of the frequency divider 8.

Abstract: A digital audio disc (DAD) reproducing apparatus comprises pulse width detection and pulse width-to-voltage conversion means for detecting a signal having a predetermined pulse width such as a maximum or minimum pulse width of code modulated digital data signals reproduced by a pickup and converting the detected signal to a voltage proportional to the pulse width, and pulse width error detection means for detecting an error between the converted voltage and a reference voltage corresponding to a reference pulse width. Since the pulse width of the digital data signal changes with a clock rate, the error from the reference voltage represents an error in the clock rate.

Abstract: A single ended, separately driven, resonant DC-DC converter including a transformer, a capacitor connected in parallel with a primary winding of the transformer, a switching transistor connected between one end of the primary winding of the transformer and one end of a DC power source, and a blocking oscillating circuit for driving the switching transistor. The blocking oscillating circuit is directly driven by the DC power source and contains circuits for properly setting a pulse width and a pulse stop period of output pulses from the blocking oscillating circuit.

Abstract: The presence of components of a frequency lower than that of the wanted component in the output of a pulse-width-modulated inverter (PWM) is highly undesirable when the inverter is supplying an induction motor. The generation of subharmonics can be avoided by making the carrier frequency an integer multiple of the output frequency. However, this restricts the operating range of the inverter. To obtain a wide output frequency range, it is necessary to change the ratio between the carrier frequency and the output frequency when the carrier frequency becomes either too high or too low for satisfactory operation. This technique has become practical as a result of advances in microelectronics. It is shown that, although the ratio of an ideal PWM waveform may be changed without significantly affecting the magnitude of the wanted component in the waveform, ratio changing will always result in a change in the output voltage of the inverter, owing to the practical limitations of the power circuit, unless steps are taken to compensate for these limitations.

Abstract: This paper presents a technique for optimizing the baseband pulse shapes in digital angle modulated signals to minimize the fraction of out-of-band power for a given channel bandwidth. As examples of practical interest, the optimization is carried out for channel bandwidths up to three times the bit rate and for the range of modulation indices usually encountered in digital transmission. Results for MSK-type signals appear as a special case.

Abstract: A magnetic amplifier which has a main winding and at least one secondary reset winding, and a core composed of amorphous magnetic material, the amplifier being arranged to operate at a frequency greater than 20 KH z . The invention also includes a switch mode converter which includes such a magnetic amplifier arranged to regulate the output of the converter by pulse width modulation.

Abstract: Analytical and experimental considerations on the large-signal transient-responses of the buck-type switching regulator are described. The behavior under the large-signal operation is defferent from the case of small signal because of the satulation characteristics of the PWM feedback controller. The effect of this nonlinearity is analyzed by deviding its operation into three modes. As a result, the maximum peak values of the inrush current and output voltage are obtained analytically both for the start-up and for the step change of the load current.

Abstract: An addressable transducer is disclosed for use in monitoring the values of physical conditions in connection with long electric lines, such as telephone cables. Multiple transducers are connected across a single pair of transmission lines which extend from a central station and supply a DC voltage to the transducers. Each transducer has an assigned address in the form of a binary code. An address signal is transmitted on the transmission lines by pulse width modulation of the line voltage. An address detector converts the address to a binary code and the transmitted address is compared with the assigned address. When the assigned address is received, a variable frequency current sink oscillator is turned on and connected across the lines. The oscillator has a frequency determined by a sensor responsive to the physical condition being measured and modulates the line current at that frequency. The frequency of the line current modulation is measured at the central station and represents the value of the physical condition.

Abstract: A dual slope pulse width modulation regulator for separate control of two independently operative power supplies is provided. An oscillator supplies a triangle wave having a period T signal to each of two separate DC comparators each of which also receives an analog error signal related to the difference between a power supply output signal and a predetermined reference level. The outputs of the DC comparators are coupled to a pair of AND gates which are alternately enabled by a digital output signal of the oscillator with the digital output signal having output states corresponding to the duration of first and second rates of change of the triangle wave signal which occur during each period T. The outputs of the AND gates correspond to pulse width modulated drive signals which are utilized to control the excitation of independently operative power supplies having output sensor circuits which sample the output of the power supplies and result in providing the first and second analog error signals. During each period T separate, independently operative pulse width modulation power supply control signals are provided through the alternate use of the first and second rates of change of the triangle wave signal of the oscillator to provide pulse width modulation control signals.

Abstract: In an ultrasonic wave distance detection system, an ultrasonic wave pulse radiated into the selected area is reflected on an object. Said reflected ultrasonic wave pulse is partly received by an ultrasonic wave transducer. The received signal is supplied to a variable gain amplifier, noise components are removed from the amplified signal through a band pass filter, the noise removed signal is detected by an envelope detector, the detected signal is compared with a predetermined level by a comparator, and the output of the comparator is applied to a flip-flop circuit. As the gain of the variable gain amplifier is set to be a lower level only at the beginning of the ultrasonic wave pulse to minimize the amplification of unnecessary signals without reducing the detection efficiency, a signal can be surely obtained which has a pulse width corresponding to the distance between the system and the object and thus the distance can be detected or measured.