Showing papers on "Buck converter published in 1985"

State-plane analysis of parallel resonant converter

Abstract: A method for analyzing the complex operation of a parallel resonant converter is developed, utilizing graphical state-plane techniques. The comprehensive mode analysis uncovers, for the first time, the presence of other complex modes besides the continuous conduction mode and the the discontinuous conduction mode and determines their theoretical boundaries. Based on the insight gained from the analysis, a novel, high-frequency resonant buck converter is proposed. The voltage conversion ratio of the new converter is almost independent of load.

DC-AC converting arrangement for photovoltaic system

Abstract: An improved DC-AC converting arrangement for a photovoltaic system, which makes it possible to supply power at high efficiency by providing a driving control system arranged to stop operation of a DC-AC converter when a load power of the DC-AC converter falls below a predetermined reference value, and to restart the operation of the DC-AC converter when the load power exceeds the predetermined reference value.

DC-AC inverter with overload driving capability

Abstract: A DC-AC inverter includes a bridge converter for converting an input DC into an output AC signal which uses field-effect transistors in the bridge circuit. The characteristics of the field-effect transistors enable the bridge converter to temporarily supply power in significant overload conditions. A DC-DC converter may also be included between the DC power source and the bridge converter to provide voltage boosting, when required. Field-effect transistors are also included in the DC-DC converter for power switching. The duration and amount of overload current output by the bridge converter is monitored and when an overcurrent condition beyond a predetermined amount or duration is detected, the bridge converter is disabled. The bridge converter is reenabled at a predetermined time thereafter. A plurality of field effect transistors may be connected in parallel at each location wherein a solid state power switching device is used in the inverter to thereby multiply the power handling capacity of the inverter as a whole.

Study of a resonant converter using power transistors in a 25KW x-rays tube power supply

Abstract: This paper describes a converter whose purpose is to feed an χ-rays tube (25 KW, 140 KV) from the industrial main power supply (380 V, 50 Hz). The authors justify the structure of this generator that is constituted by an inverter using power transistors and a transformer-voltage multiplier set which are connected by a series resonant circuit. The control logic of the transistors gives them the dual properties of these of thyristors. An accurate analytical study of this system allows to predetermine the characteristics of this converter now in its industrialization phase.

Power converter apparatus and control method thereof

Abstract: A power converter apparatus has at least two converters CONV1 and CONV2. The DC side of each of the converters CONV1 and CONV2 is connected to a filtering capacitor Cd which serves as a DC power source for a load device LOAD. The AC side of the converter CONV1 is connected to the secondary winding of a first transformer TR1. The AC side of the converter CONV2 is connected to the secondary winding of a second transformer TR2. The primary winding of transformer TR1 is connected in series to the primary winding of transformer TR2. The series circuit of the primary windings of transformers TR1 and TR2 is coupled to an AC power supply SUP via a single AC reactor Ls. A control method of the invention is adapted to the power converter apparatus in which plural PWM converters are used. The phase of a modulating wave (carrier) of one PWM converter differs by a predetermined degree from that of another PWM converter.

A DC to 3-Phase Series-Resonant Converter with Low Harmonic Distortion

Abstract: A type of dc to 3-phase series-resonant converter (s.r.converter) or potentially submegawatt industrial applications is presented. The converter provides variable-frequency sine-wave currents, with low harmonic distortion at the output terminals, and with the frequency ranging from -200 through dc to +200 Hz. The converter can transfer power in both forward and reverse power-flow directions to almost any type of load circuit. The methods of control are formulated such that they can be implemented easily with high-speed logical circuits. Test results for a 1-kW demonstration converter are supplied.

Charging control system in solar generating device

Abstract: PURPOSE: To obtain a charging control system high in working efficiency by removing a DC/DC converter when the ratio between the input voltage and the output voltage of the DC/DC converter is kept between the conversion efficiency of the DC/DC converter and the reciprocal of said conversion efficiency. CONSTITUTION: When an accumulator 3 has a level less than a full charge mode, the DC voltage generated by a solar battery 1 is raised or dropped via a DC/DC converter 5 after a switch 12 is closed. Then a charging current and a load current are supplied to the accumulator 3 and the load 4 respectively in response to the output voltage of the converter 5. While the rise and drop are nor required for the output voltage of the battery 1 by the function of the converter 5 when the ratio between the output voltage V 0 and the input voltage V i of the converter 5 is kept between the conversion efficiency FC of the converter 5 and its reciprocal 1/FC. Thus an input/output voltage comparison control circuit 9 opens the switch 12 and separates the converter 5 from the load 4. COPYRIGHT: (C)1987,JPO&Japio

Current-source power converting apparatus with self-extinction devices

Abstract: A current-source power converting apparatus having a three phase AC-DC converter composed of self-extinction devices for converting an AC power furnished from an three phase AC power source into a DC power and a DC-AC inverter connected with the AC-DC converter through a DC reactor for re-converting the DC power into a three phase AC power to supply the re-converted power for a load. When the failure of the AC power source is detect according to one embodiment, the AC power source is detached from the AC-DC converter and a battery is connected between arbitrary two phases at the input end of the AC-DC converter. After that, the DC power of the battery is supplied for the DC-AC inverter intermittently by switching the corresponding self-extinction devices of the AC-DC converter and controlled by varying the duty ratio of the switching operation.

Control circuit for power converter apparatus

Abstract: Disclosed is a control circuit for a power converter apparatus using self-extinction devices as switching devices, in which turn on and turn off operations of the self-extinction devices are controlled by gate pulses which have been subject to pulse width modulation with a pulse train having a pulse width which is sinusoidally varied, and, at the same time, the self-extinction devices in same phase are made conductive in a predetermined period corresponding to an output voltage reference value to make an output of the power converter apparatus be in a shorted state in the sense of DC current to thereby control the output of the power converter apparatus

Switched power supply comprising a free-running flow converter and electrically separated control loop

Abstract: A switched power supply has a rectifier arrangement for generating a DC voltage from an input AC voltage. A converter arangement in the power supply has a switching transistor and a transformer. The converter arrangement is designed as a free-running flow converter, whereby the switching transistor is switched on in the current-free condition. A control stage with an electrically separated control loop is provided at the secondary side, whereby the control stage acquires the deviation of an output DC voltage from a prescribed value and sets the pulse duty factor for the switching transistor via the control loop.

Current fed boost converter

Abstract: A power supply comprising a high impedance source and a regulator configured as a boost type converter is disclosed. The duty cycle of a shunt switch in the regulator is controlled so as to be increased or decreased in order to respectively decrease or increase the regulator output voltage.

Monitoring switch mode converter performance utilizing duty cycle

Abstract: A method and circuitry are disclosed for monitoring the performance of a switching system such as a switch mode converter by monitoring the duty cycle of the system. With respect to a switch mode converter, its duty cycle is a parameter which determines whether or not the converter is in jeopardy of loosing its ability to regulate an output voltage. As long as the duty cycle of the converter is below a given threshold, which may approach 100 percent, the converter has the ability to continue regulating the output voltage. The method and circuitry disclosed herein monitor a signal of the converter having a duty cycle related to the duty cycle of the converter and provide a signal indicating when the duty cycle of the converter is equal to or greater than a predetermined threshold duty cycle.

Switch-mode power supply having a free-running forward converter

Abstract: A switch-mode power supply has a rectifier for producing a small d.c. voltage from an input a.c. voltage, and a converter which comprises a switching transistor and a transformer. The converter arrangement is a free-running conductive converter and the switching transistor is switched on in the currentless state.

Apparatus for generating a multi-frequency signal

Abstract: An appartus for generating a multi-frequency signal includes a D/A converter, two converter circuits connected to the D/A converter for determining a respective connecting instant, two controlled waveform counters each being connected to a respective one of the converter circuits, a D/A cycle control connected to the converter circuits for monitoring the converter circuits, a sample-and-hold circuit having divider capacitors and being connected to the D/A converter, and holding capacitors connected to the sample-and-hold circuit.

DC-AC series-resonant converter system with high internal frequency generating multiphase AC-waveforms for multikilowatt power levels

Abstract: A new method of power pulse modulation with internal frequencies of tens of kHz which is also suitable for multikilowatt power levels is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow. The power circuitry of the converter is provided with one single high-frequency resonant link in the direct energy path. Natural current commutation of the thyristors is obtained by the use of a series-resonant circuit for power transfer and control. Consequently, switching losses can be reduced to a minimum without compromising the reliability of the solid-state components. The high pulse frequency allows the principle of modulation and demodulation to be applied for fast system response and output waveforms with reversible power flow with low distortion. Test results of a converter system generating three phases, sinusoidal waveforms independent of the load characteristics, demonstrate the significant aspects of this class of power conversion. The material presented indicates the possibilities for fast-acting polyphase dc-to-ac and ac-to-ac converter systems.

Power supply with free oscillating forward converter and electrically insolated control loop

Abstract: The invention relates to a switching power supply having a rectifier arrangement (BG) for generating a DC voltage (UG) from an alternating input voltage (UE), and having a switching transistor (T1) and a transformer (U) having converter arrangement. According to the invention provides that the converter arrangement is designed as a freely oscillating forward converter, wherein the switching transistor (T1) is turned on in the currentless state, and in that a secondary-side regulating stage is provided with an electrically isolated control loop, wherein the control step, the deviation of a DC output voltage (UA) of a predetermined detected value, and adjusts via the control loop, the duty ratio for the switching transistor (11).

Switched power pack with free-wheeling flow converter and switched controller at a secondary side

Abstract: A switched power supply has a rectifier arrangement for generating a DC voltage from an input AC voltage. A converter arrangement thereof has a switching transistor and a transformer. The converter arrangement is designed as a free-running flow converter wherein the switching transistor is switched on in a current-free condition. A secondary side of the converter arrangement comprises a secondary switch controller which is synchronized by the transformer and which regulates an output DC voltage.

A power converter for a motor control system

Abstract: An AC motor drive includes a power converter (10 to 53) which supplies current to a DC bus (3) from three-phase power lines (4, 5, 6). An inverter (2) drives the motor (1) from power delivered to the DC bus (3) and it regenerates power to the DC bus (3) when the motor (1) is decelerated. The power converter (10 to 53) in turn regenerates the power to the power lines (4, 5, 6) by controlling line current such that it is substantially in-phase with the applied line voltages. Current overload protection (60 to 64) is provided for the transistor switches (16 to 21) employed in the power converter bridge circuit.

High-speed feedback circuit with ungrounded load

Abstract: A high-speed feedback circuit for use with, particularly, a buck or buck derived regulator (power processor). The circuit employs a voltage developed by the regulator after the switch and before the filter. From this voltage, a current is developed which is combined with (subtracted from) a reference current. The combined current is integrated in a capacitor to develop a voltage used to drive the switch. The load is not referenced to ground.

State-Plane Analysis of Quasi-Resonant Converters

Abstract: A comprehensive analysis of the high-frequency quasi-resonant buck converter is presented using the graphical state-plane technique. The analysis has revealed, for the first time, the presence of several unfamiliar modes of operation. The voltage conversion ratio and boundary switching frequency for each mode are derived. The existence of various operating modes are verified experimentally.

Digital-to-analogue converter arrangement

Abstract: A digital-to-analogue converter arrangement employs a digital-to-analog converter circuit (10) of a type producing an output voltage V(n') such that: ##EQU1## where k is a constant, E is a voltage applied to a reference voltage input, n' is a binary number applied to a binary signal input and M' is the maximum value n' can attain. The converter arrangement includes a negative feedback network (20) coupled between the output (13) of the digital-to-analogue converter circuit and the reference voltage input (14).

The effects of compensation on load transient response in switched mode power converters

Abstract: Using computer simulation, three loop stability compensation techniques are applied to a buck switched mode power converter to determine their effects on load transient response . A buck converter computer model is developed and the load transient responses of three compensation techniques are simulated. The results are tabulated and evaluated to establish quideiines to aid in the design of switched mode power converters that operate under load transient conditions. Also included are a discussion of the need for compen­ sation and a description of the two industry used compensation techniques dominant pole compensation and two real zero cancellation compensation; and a third, new compensation technique two complex zero cancellation compensation. The design equations for this new compensation technique are given in the appendix and an HP41-C calculator program is listed to aid in the selection of component values for the circuit.