Abstract: An electric welding apparatus which, for controlling at least one welding parameter, such as welding voltage or welding current, comprises a switching mode power supply (SMPS) as control element, the switching mode power supply preferably being regulated on the primary. The actual values of voltage and current are taken from the output of the switching mode power supply and fed to an analog control circuit. The set values of voltage and current are fed to a microprocessor via an entry keyboard, and in the microprocessor they are stored in a memory and passed on in analogous form to the analog control circuit which carries out a comparison of set value and actual value and, in dependence thereon, produces an error signal that is fed to a pulse width modulator of the switching mode power supply. The pulse width modulator is connected to the driver stages of the switching stages of the switching mode power supply, which switching stages are designed as boost regulator of buck regulator, and thus a pulse width modulation of the current pulses of the switching stages is effected in dependence on the difference between actual and nominal value. The converter section of the switching mode power supply preferably is designed as a modified single-ended buck regulator or as a push-pull full bridge, wherein it is operated at a fixed clock frequency of about 25 kHz. The secondary coil of the transformer of the switching mode power supply being either direct in connection with the output connection terminals of the switching mode power supply, or a secondary rectifier is connected between the secondary coil and the output connection terminals, whereby the secondary rectifier can be bridged by switch means.

Abstract: A two-wire electronic dimming ballast arrangement for one or more gas discharge lamps is disclosed which includes an inverter driven by a variable pulse width electric power and a control system for modulating the pulse width of the variable pulse width square wave electric power driving the inverter A unique distortion suppression system is provided for suppressing current abberations and achieving substantially a unity power factor

Abstract: A switching regulator power supply operates at a variable high frequency and pulse width with low power dissipation and a minimum of complexity. The transformer primary windings which are included as part of a self starting circuit start a pulse generator having a variable pulse width and variable frequency. During operation, the input RC network of the pulse generator, in response to the input rectified AC line voltage, conditions the pulse generator to generate output pulses whose widths vary as a function of changes in the input rectified AC voltge. An error circuit coupled to the secondary winding compares the output DC supply voltage to a reference voltage and generates an error signal which is applied through a coupling circuit for further adjusting the frequency of the pulse generator within a desired range to existing load conditions.

Abstract: Disclosed is a fuel injection valve drive circuit for use in an internal combustion engine wherein the excitation current supplied to the fuel injection valve winding is controlled on a feedback basis so as to maintain the specified value during the period of the valve opening command signal. A control signal based on the difference between the signal representing the excitation current and the reference signal is produced, and the excitation current is controlled by the pulse width modulation signal which is produced based on the magnitude of the control signal.

Abstract: A simple multiple pulsewidth modulated (MPWM) ac chopper using power transistors for 3-? power control is discussed. 120° chopping period is used for main transistors so that the circuit can accommodate resistive and lagging or leading power factor loads. Only 1-? sensing is used for 3-? control. An alternate economical power and control schemes for 3-? MPWM ac choppers suitable only for resistive loads is also suggested. The experimental results for 12 choppings per cycle are given.

Abstract: A hybrid circuit for producing a three-phase reference sine wave required with PWM inverters is described in this paper. The principle of the circuit is simple and the implementation of the circuit is easy. The circuit has all the features discussed in the literature. The unit built has, apart from the three-phase sine waves, balanced three-phase square and triangular waves. A high-frequency triangular wave already available in the circuit can be used for the PWM control circuitry. The scheme can easily be extended to generate sine waves of any number of phases.

Abstract: self-synchronization coding technique for synchronous transmission of digital signals, and apparatus used with this technique. In an exemplary embodiment, the coding technique uses relatively positive and relatively negative pulse of fixed predetermined duration. For electrical pulses, the reference point is preferably a baseline zero. LEi at the leading edge of the i th bit cell, the value of the ith cock is encoded as a positive pulse in the case of a logic "1" (eg 82A) or of a pulse negative (eg 82B) in the case of a logic "0" (step 41, 42A, 42B). In addition, if the next bit (that is to say (i + 1) th bit has the same value, a pulse of opposite polarity is injected into the i-th bit cell after the pulse from the leading edge (p .. .ex 82D) Thus, alternate positive and negative pulses and the information content of the encoded signal have no DC component, this facilitates an AC coupling Moreover, the coding technique is independent of the flow. . binary (that is to say of the frequency) and is usable over a wide range of bit transfer rate the receiver may decode the synchronous signal if he knows the pulse width, it has not need to know the transmitter's transmission rate and a bit transmission rate may even change from one bit cell to another. for application to the optical fibers, a baseline of non-zero is used. the zero optical output level replaces the level of electrical negative pulse, the optical half-maximum output level replaces the electrical zero level and the maximum optical output level replaces the electrically positive pulse.

Abstract: The response characteristics of an electronic neuron model proposed by the authors are investigated. Periodic stimulating pulse sequences with a fixed frequency are applied to the analog neuron model and the response pulse sequences are studied. In the degenerate case, the state transition of the neuron model during one period of the stimulating pulse sequence is described by a first order piecewise linear difference equation with a jump. It is shown that the periodic response pulse sequences of the neuron model belong to a special class of pulse sequences generated by a simple algorithm, and that the relation between the pulse width (or amplitude) of the stimulating pulse and the firing rate of the neuron model takes the form of an extended Cantor function.

Abstract: A description is given of a number of new circuit techniques, useful primarily in the control hardware of inverter drives using ``sub-harmonic''- or ``triangulation''-based pulsewidth modulation algorithms. Most aspects of such a system are covered. These include generation of the ``reference'' and ``carrier'' waveforms, carrier merging (including an asynchronous/synchronous carrier transition), output amplitude control, and sequence filtering. While the emphasis is on the triangulation approach, the majority of the text is relevant to the implementation of pulsewidth modulation processes in general. Some experimental data are included.

Abstract: The high voltage field effect transistor has a drive circuit for pulse width modulation, which includes a small transformer coupled to the gate and source with a diode in series at the gate, so that a very short on-drive pulse charges the gate capacitance, and the charge is held by the diode. Another FET has its output connected between the gate and source of the high voltage FET, and its input coupled to another small transformer so that it is turned on for a short time by a very short off-drive pulse to discharge the gate capacitance and thus turn off the high voltage FET. A transformer drive circuit includes two one-shot devices connected to the pulse width modulator as leading and trailing edge detectors respectively, with their outputs connected via FET's to the on-drive and off-drive transformer primaries respectively, to provide pulses of 100-200 nanoseconds.

Abstract: A digital current regulator circuit, especially useful for a DC motor, is described which is fed directly, i.e., without power transformers, from the AC mains, via power transistors (T1-T4) that are controlled by pulse modulation and which can work in four-quadrant operation. An A/D converter (12) generates from samples of the motor current, an actual-value signal in the form of a multi-bit parallel binary code; and a binary comparator (20) compares the actual-value code with a theoretical-value code and generates binary error signals if the actual value is greater or less than the theoretical value. To provide DC-isolation of the power transistors and associated circuitry from the control circuitry that generates the error signals, the parallel bits of the actual-value code are transmitted to the control circuitry through an opto-electronic coupler (14). Other opto-electronic couplers (16, 30) can be provided to transmit other control signals.

Abstract: We report the generation of short light pulses of 23‐ps duration from an unbiased proton implanted double heterostructure cw laser by direct gain modulation. Repetition frequencies up to 10 MHz and a typical peak power of 300 mW are achieved. The time behavior of the light output is largely independent of the rise and fall time of the modulation current, since the first relaxation oscillation of the laser is utilized.

Abstract: A PWM, controlled current, voltage source inverter controls an induction motor in response to signals from a power factor control circuit. The power factor control circuit receives signals related to motor terminal voltages and multiplexes them to a comparator. The inverter and multiplexer are sequenced each time the comparator input reaches a reference level. The frequency of the inverter is thus self generated. The power factor of the system can be controlled to implement a variety of control strategies.

Abstract: Reflective array compressors with metal gratings are attractive devices because they can be fabricated in a single layer photolithographic process. However, known weighting techniques for'achieving the desired time response suffer either fran sensitivity to fabrication tolerances or fran complex reflection behaviour. We use a new amplitude weighting scheme whereby only the positions of metallic strips in the array are shifted. These shifts are caused by an additional phase modulation of the desired waveform with an oscillating function whereby the number of oscillations exceeds the time-bandwidth product. The envelope of the oscillating function depends on the required weighting. This weighting technique is free of additional secondary effects, insensitive to technological linewidth-deviations and accurate to calculate and to design. Fabricated matched filter sets with a time-bandwidth product of 12 and nonlinear frequency modulation (FM) attain -41 dB sidelobes in the compressed pulse.

Abstract: A switching power supply has a power switching transistor furnishing a series of shaped pulses to output means for providing an output voltage, has control means including a voltage controlled oscillator responsive to the output voltage for providing control pulses whose frequency is representative of the output voltage level, and has saturable transformer means coupling the control pulses to the switching transistor for driving the transistor to regulate the output voltage within a selected range. First winding means on the saturable transformer drive the transformer to saturation with each control pulse and other winding means forward bias the switching transistor to conduct while the transformer is being driven to saturation and thereafter reverse bias the transistor to rapidly turn it off as the transformer recovers from saturation. The power supply includes means for varying transistor switching frequency and pulse width for regulating output voltage.

Abstract: PURPOSE:To prevent the variation of the distance measuring accuracy through the feed back control of the amount of light emitted from a light emitting means to always make the amount of light received by a light receiving means constant CONSTITUTION:Pulse modulated light emitted from a light emission element 1 and reflected on a measuring objective 4 is received by a semiconductor position detector 5 at the light receiving point x in the light receiving surface 5a The detector 5 provides position signals in the form of signals currents IA and IB corresponding to the light receiving point The light receiver 5 generates continuous signal voltages VA and VB corresponding to the currents IA and IB, respectively An adder 14 adds the signals VA and VB, then sends the result to a pulse modulation circuit 2 The circuit 2 generates oscillating pulses P0, the frequency of which varies in inverse proportion to the signal VA+VB Thus the element 1 is subjected to pulse modulation and to feedback control so that the amount of light received by the detector 5 is always kept at a fixed level even if the distance X from the measuring objective 4 varies

Abstract: A half wave pulsewidth modulation (PWM) control device based on the principle of the half wave magnetic amplifier has interesting characteristics for controlling a high frequency switching regulator. We call it the magnetic power controller. By using the magnetic power controller of an amorphous core having a highly rectangular dynamic hysteresis loop and using a self-oscillating inverter, a highly reliable 200kHz switching regulator is realized, in which the current surge caused by the reverse recovery of the diode is well suppressed by the surge suppression characteristic of the magnetic power controller. The efficiency of this switching regulator is higher than 80% for an input voltage 110 ± 20V and for an out-put power 98W (5V, 10A and 24V, 2A). Peak to peak voltage of the switching noise observed in the output voltage is as small as 10mV under the above condition. The amorphous core used in this paper is of a Corich system with approximately zero magnetostriction.

Abstract: Conventional UPS equipment employs a tandem charger, battery, and inverter to isolate critical loads from utility disturbances and failures. Since two distinct stages of power conversion -- charger and inverter -- are required, this method is both inefficient and expensive. This paper describes a new circuit topology and operating method that uses a single four-quadrant PWM sine-wave inverter to both regulate the critical load and charge the standby battery. The complete power system consists of an inverter coupled to the utility through an inductor. The critical load is connected directly across the inverter output. This allows the inverter complete control of the load voltage and waveform. When the inverter is operated synchronously with the utility, power flow is regulated by varying the phase angle between the inverter and the utility. The phase angle is automatically adjusted using an 8-bit microprocessor to meet the load and battery charge current requirements. The microprocessor also performs housekeeping and display functions. Since the system requires only one power conversion stage, throughput efficiencies exceeding 90% have been achieved at the 3kW power level. Power densities also have been improved because of its "chargerless" construction. General principles of operation with phasor diagrams including actual system waveforms are presented as well as advantages and disadvantages of this approach with respect to conventional UPS equipment.

Abstract: A high performance variable speed drive system using current source inverter fed induction motor is described. The principle of the drive control is based on the field-orientation method, where the stator current is used as the vector quantity. To improve the system response and to operate smoothly at low speed, a current pulsewidth modulation (PWM) control is provided by means of a feedback loop. This system operates stably and shows a high dynamic performance in a wide range, from zero to rated speed. Dual current source inverter is applied to this drive system which results in a remarkably low copper loss of the motor, even in PWM operation.

Abstract: Characteristics of variable frequency power supplies are compared, including sine wave, six-step square wave, and pulse width modulated (PWM) types The effects of the complex voltage waveforms and variable frequency supplies on motor efficiency, heating, torque, winding stresses, and low speed pulsating torques are described Possibilities for customizing induction motors for use with variable speed drives are considered

Abstract: Disclosed is a method and apparatus for operating an induction motor by an inverter of the pulse-width modulation (PWM) type, wherein the slip frequency is calculated from the speed command and the actual motor speed so as to produce the phase compensation signal, and the frequency command for the inverter is produced by adding the phase compensation signal, the slip frequency signal and the motor speed signal. The primary current command is calculated from the slip frequency, the amplitude ratio of pulse-width modulation is calculated basing on the primary current command and the actual primary current, and the inverter is controlled in accordance with the amplitude ratio so as to control the primary current of the induction motor.

Abstract: A DC to DC switching regulator includes a first pulse width modulator (PWM) (26) and two switching transistors (48) and (50) that are coupled to a transformer (18) to generate an output signal that has pulse widths variable in response to the PWM (26). The output of the transformer (18) is rectified to provide a regulated DC output. A second PWM (78) is provided to convert the amplitude of the regulated DC output to a stream of pulses that are input to an isolation transformer (112) by a push-pull arrangement of transistors (118) and (120). The pulse width of the pulses input to the isolation transformer (112) is variable as a function of the level of the regulated DC and the amplitude thereof is a constant referenced to the internal reference of the PWM (78). The output of the isolation transformer (112) is rectified and filtered to provide an error signal that varies in response to the pulse width of the output pulses from the PWM (78). The constant amplitude, variable width pulses output by the PWM (78) provides a signal that does not vary in response to noise on the regulated DC output and the error signal derived therefrom is input to the PWM (26) to vary the pulse width thereof to maintain regulation on the regulated DC output.

Abstract: A video display terminal (VDT) is provided with a controller having six digital logic lines capable of defining sixty-four different colors. An eight color color display monitor (CDM) having three red, green and blue (RGB) video input lines is connected to a pulse width modulation converter capable of converting the sixty-four digital input conditions on the six low level voltage logic lines to sixty-four different color control conditions on the three video input lines.

Abstract: A light dimmer control system for controlling the current supplied from a DC power source to high power illuminating lamps. The current fed to the lamp is controlled by manually setting the width of the pulsed output of a pulse width modulator by means of a potentiometer or the like appropriately connected to the pulse width modulator. The output of the pulse width modulator drives an output driver circuit which is connected in series with the current path to the lamp. The lamp power is provided from a DC source which is controlled by the output driver circuit in series with the lamp. The power for the semiconductor components of the DC controller, which includes the pulse width modulator, is provided from the same DC source and stepped down by a DC-DC converter. A logical control circuit is employed which enables the energization of the system only when both the polarity of the DC input supply is correct and the low voltage DC is on, thereby minimizing the possibility of damaging system components.

Abstract: PURPOSE:To obtain a picture image which provides visually natural feeling by forming a threshold pattern on the basis of a fine picture element at a prescribed position other than both pattern end parts, when obtaining a binary- coded picture image signal of a shade picture by using the threshold pattern. CONSTITUTION:When a shade image is to be converted into a binary signal, a data output signal SQ from a hexadecimal counter CHE is inputted to a matrix memory MXM, and an obtained threshold signal STH with a specified column address is inputted to a comparator COM, where it is compared with a data signal SD to perform binary-coding operation. A threshold pattern stored in the matrix memory MXM has an increase in pulse width almost from the center to the left and right circumferences by turns. Consequently, it has no Y-directional linearity along the edge of picture elements, and unnaturalness due to variation of line width is improved.

Abstract: To realise the full output potential of a PWM inverter, it is necessary to make the transition from a PWM output waveform to a square-wave output. This is usually achieved by dropping pulses from the PWM waveform, which results in step changes in the output voltage. It is shown that, generally, pulse dropping is unavoidable except with one particular type of inverter circuit. A waveform generation strategy is proposed for this type of inverter which allows the transition from PWM to square-wave output to be made without voltage-waveform discontinuities of any kind.

Abstract: PURPOSE:To prevent the hunting of a motor by feeding back a value corresponding to variation of the low frequency in the output current of an inverter to a voltage frequency converter determining the output frequency of the inverter. CONSTITUTION:An output of a pulse width modulation voltage type inverter 14 is applied to an induction motor 6 by way of a current transformer 5. A command frequency reference from a frequency setting device 7 and an output voltage of the inverter 14 are applied to a voltage controlling circuit 10 to form a voltage control signal, which is applied to a pulse width modulation controlling circuit 11. A load current detection signal from the current transformer 5 is inputted into an arithmetic circuit 13 with the command frequency reference through a phase inverter 12. The arithmetic circuit 13 react to variation in a low frequency of said detection signal but not to that of a high frequency. The output of the circuit is converted into or frequency control signal with a voltage frequency converter circuit and applied to the pulse width controlling circuit 11.

Abstract: PURPOSE:To stabilize a secondary coil output voltage by correcting a voltage corresponding to the voltage of a secondary coil generated in a tertiary coil through a voltage corresponding to the peak value of a current flowing through a primary coil and by performing switching control on the basis of the corrected voltage corresponding to the voltage across the secondary coil. CONSTITUTION:AC power supply 1 output is full wave-rectified by a full-wave rectifier circuit 3. This current is switched by FET 8 to flow to the primary coil L1 of a transformer 4. Also, the current flows to a secondary coil L2 and voltage corresponding to charge electrifying a capacitor C2 is applied to a load 9. In a correction circuit 6, a voltage corresponding to the voltage (voltage across the secondary coil L2) applied to the load 9 generated in a tertiary coil L3 is corrected by a voltage corresponding to the peak value of the current flowing through the primary coil L1 supplied from a detection circuit 5. In PWM control circuit 7, drive pulse is applied to the gate of the FET8 on the basis of the corrected voltage corresponding to the voltage in the secondary coil L2.