Showing papers on "Buck–boost converter published in 1986"

FET power converter with reduced switching loss

Abstract: A DC to DC power converter having reduced switching loss for operation at high frequencies. As disclosed, a buck, or forward, converter includes a first FET as the switching device in series with an inductor and a second FET as the flywheel device. At the common node to which the two FET's and the inductor are connected, there is sufficient capacitance that the FET's may be turned off without appreciable voltage change across the FET's. The value of the inductor is chosen, with respect to the input and output voltages and frequencies of operation involved, to insure that the inductor current polarity reverses each cycle, raising the node voltage to the level of the input voltage, substantially eliminating turn-on losses of the first FET. Control circuitry is provided for regulation of the power converter to control the peak-to-peak current in the inductor and to insure that at least a selected minimum value of the inductor current is present for each cycle of operation of the converter. An over-voltage protection circuit for the output of the converter is also provided.

Bi-directional buck/boost DC/DC converter

Abstract: A bi-directonal DC/DC converter includes a first power switch coupled to a first input/output of the converter, an energy storage element coupled to the first power switch, a second power switch coupled between the energy storage element and a second input/output of the converter and means for controlling the first and second power switches so that one of the power switches is opened while the other power switch is alternately opened and closed to transfer power from one input/output to the other input/output.

Boost/buck DC/DC converter

Abstract: A bi-directional DC/DC converter includes a first switch coupled to a first input/output of the converter, a first input/output energy storage element coupled to the first input/output of the converter, a second input/output energy storage element coupled to a second input/output of the converter, an intermediate energy storage element coupled between the second input/output and the first switch and a second switch coupled to the intermediate energy storage element and to the first switch. A pulse width modulator operates the first switch between on and off states while the second switch is maintained in an off state to operate the converter as a buck converter, during which time the power is transferrred from the first input/output to the second input/output. A further pulse width modulator operates the second switch between on and off states while the first switch is maintained in the off state to operate the converter as a boost converter, during which time power is transferred from the second input/output to the first input/output.

An AC-to-DC Converter with Improved Input Power Factor and High Power Density

Abstract: A novel single-phase switch-mode rectifier (SMR) structure is proposed and analyzed. The proposed converter structure employs a synchronous front-end rectifier (SFER) stage which provides high-quality input characteristics with small input filtering. Consequently the proposed converter structure exhibits high power density and has low implementation cost.

Automatic transfer switch for a wide range of source voltage

Abstract: An automatic transfer switch is taught which includes as part thereof a voltage sensing device which is interconnected with one of the lines to be monitored and controlled by the automatic transfer switch and neutral. This voltage may vary over a wide range and it is desired to provide a universal transfer switch control for operation over the wide range. The output analog voltage is provided to an analog-to-digital converter which has a maximum number of output bits. In order to keep the resolution of the output digital signal from the analog converter as high as possible, it is necessary to range the input voltage according to a menu of potential ranging values which are stored in the memory of a microprocessor. A programming device is utilized to input the line voltage and the microprocessor determines the maximum value for the ranging constant as a function thereof. The output analog voltage is reduced by this factor then provided to the analog-to-digital converter. The greater the reduction, the lower the sensitivity. However, the microprocessor chooses only that amount of discrete reduction necessary to prevent the expected input line voltage from exceeding the maximum digital output capacity of the A-to-D converter. The output of the A-to-D converter is then supplied to the microprocessor for processing and the amount of reduction is compensated for by multiplying the output signal by the increase of the conversion factor.

Current fed regulated voltage supply

Abstract: The invention is a locally isolated regulated power supply providing a regulated dc power output from an ac current source having a large dynamic range. The power supply comprises an ac-to-dc converter for providing a rectified dc output from an ac current input. The converter includes a current transformer in combination with a rectifier. The current transformer has a saturable magnetic core for receiving primary and secondary windings. The current transfomer produces a reduced secondary output voltage that is a function of the ac system current characterized by the decreased coupling between the core and secondary winding as the core approaches saturation during substantial increases in the ac system current. One or more secondary windings and associated circuitry can be provided. In addition, an electronically controlled switch or shunt having as inputs a predetermined reference voltage and the dc output voltage of the rectifier or a signal equivalent thereto is connected across the converter. The switch provides for the continual shunting of the converter whenever the dc output voltage is equal to or greater than the predetermined reference voltage. A voltage support capacitor is connected across the output of the converter for maintaining the output voltage proportional to the selected reference voltage. An isolation diode is used to isolate the voltage support capacitor from the converter during those periods of time when the converter is being shunted by the electronically controlled switch. This prevents the discharge of the capacitor.

Power circuit with high input power factor and a regulated output

Abstract: A single power converter is capable of drawing low distortion current from an AC line and delivering DC or AC power to a load. The single power converter is used to independently control the input current and the output current. The power converter transformer has an output winding which is controlled by pulse-width modulation (PWM) and a frequency controlled boost winding for controlling input current.

Power failure stop circuit for a converter

Abstract: The voltage in a converter 20 is compared with a reference voltage to detect an input power failure, in response to which a motor driven by the converter is automatically decelerated in accordance with a stored signal pattern/speed reduction curve such that the energy regenerated by the motor is equal to its power consumption. The DC bus voltage of the converter is thus maintained substantially constant during the regenerative braking of the motor, and it is promptly halted without resort to any mechanical braking unit.

Buck-boost parallel resonant converter with inductive energy recovery circuit

Abstract: A DC-AC converter circuit for a power supply contains a parallel resonant circuit topology. Accordingly, stray capacitance associated with the converter forms a part of the resonant circuit and assists in setting the resonant frequency thereof. The energy in the stray capacitance which is normally lost is recovered by the resonant circuitry. A coupled inductor is connected in series with a primary winding of an output transformer of the converter. The coupled inductor includes a resonating inductor winding and an energy recovery winding which are tightly wound out of phase with one another. Energy from the resonant inductor winding is coupled to the recovery winding when the switching elements of the converter are switched on and off. Therefore, energy otherwise dissipated in switching operation is conserved by being returned to its source. Further, the switching elements of the converter are connected in series through diodes to the return line. Consequently the converter is capable of operating either in a buck or boost mode and to switch from one mode of operation to the other.

Regulator circuit for converting alternating input to a constant direct output

Abstract: A high efficiency integrated power converter adapted for direct connection to line voltage and having on chip protection from overcurrent may be implemented utilizing a GTO-SCR as the switch element in a switching power converter such that the converter requires no external transformer or inductor based voltage reducing circuitry. The input voltage may vary over a wide dynamic range without deterioration in circuit performance due to the extremely high anode to cathode breakdown voltage of the switching element and further due to the on chip protection from excess current flow through the switching element.

Apparatus for controlling the parallel operation of an A-C output converter for a commercial power source including a circuit for simulating output current for test purposes

Abstract: An apparatus for controlling the parallel operation of a commercial power source and an A-C output converter in which the A-C output converter of a variable voltage and a variable frequency is connected and operated in parallel with the commercial power source; an impedance element is provided between said commercial power source and an output terminal of at least one phase which represents an internally generated voltage of the A-C output converter, the impedance element being connected in parallel with an output impedance of a main circuit of the A-C output converter, and the voltage and frequency of the A-C output converter being controlled so that a current that flows through said impedance element assumes a predetermined value.

Clocked direct voltage converter

Abstract: A clocked direct voltage converter with potential separation includes a control circuit for controlling the switching times of a switching transistor arranged on the primary side of the voltage converter, in which voltage converter voltage proportional to an output quantity is chopped by a controllable switch. The chopped voltage is transmitted by a transformer to the primary side of the converter, is then rectified, filtered and supplied to the control circuit. In order to obtain the largest possible control range for the converter, a further transformer is provided which transmits oscillation signal of an oscillator of the control circuit to the controllable switch on the secondary side voltage converter. By means of this oscillation signal, the controllable switch is controlled.

The Systematic Errors of a Time-Division Power Converter under Sinusoidal and Nonsinusoidal Conditions

Abstract: Systematic errors of an astable multivibrator based time-division active power converter are analyzed. Results of a computer simulation for sinusoidal and nonsinusoidal input signals are compared with test measurements of a standard converter. The paper shows that a conversion error of the power converter can be estimated from the harmonic content of the input waveforms.

Filter capacitor discharge circuit for a DC-DC converter

Abstract: A power supply circuit includes a battery power source connected by a switch to the input of a DC to DC converter. The output of the DC to DC converter is connected to a filter capacitor and a load. A crow-bar is connected to the input and the output of the DC to DC converter. The crow-bar shorts the output to ground to discharge the capacitor when the voltage at the input drops to a predetermined value.

Floating battery feed circuit using multifilar transformer.

Abstract: A substantial reduction in the common-mode noise generated by a switching-mode power converter is achieved by incorporating a multifilar-wound transformer (410) into the converter in such manner that the inter-winding capacitances cause a cancellation of common-mode, noise components at the converter output.

Low-loss voltage limiting network for isolating transformers or flux converters

Abstract: A circuit arrangement for low-loss limiting of the maximum blocking voltage of the switch element of an isolating transformer or flux converter, having a converter transformer whose primary winding is connected in series with the switch element, and having a discharge capacitor, an additional winding of the converter transformer being provided as a demagnetisation winding which is connected by means of two series-connected diodes to the input terminals of the converter, and the discharge capacitor being arranged between that connection of the switch element which is on the primary winding side and the junction of the two series-connected diodes.

New topologies of fully regulated two-output dc-to-dc converters with small frequency variation range

Abstract: This paper offers a new solution to the design of two-output dc-to-dc converters having one sole power transistor. The combination of a resonant converter and a tapped-inductor converter is the basis of this new approach which represents an improvement on previous studies. The fact that the dc voltage gain of the resonant converter is a function of the switching frequency but not of the load nor of the duty cycle and the fact that the tapped-inductor converter is a function of the duty cycle but not of the frequency nor of the load, enables the two outputs to be regulated with only small switching frequency variations and with only slight interaction between the two outputs. A prototype of this converter has been built and the results are discussed.

DA converter testing system

Abstract: A DA converter testing system for testing DA converters which convert digital information into analog information, particularly suitable for testing the dynamic characteristics of such DA converters. The DA converter testing system has an AD conversion means which receives the analog output signal of a test DA converter, operating at a conversion period greater than the waveform repetition period of the repetitive output waveform of the test DA converter. Accordingly, the fast repetitive output waveform of the test DA converter can be converted into corresponding digital codes at a high accuracy and hence the DA converter testing system is more suitable than the conventional DA converter testing system, for testing the dynamic characteristics of DA converters.

Bed converter

Abstract: The switched regulator circuit having an extended duty cycle range allows the single-ended forward converter to operate at a duty cycle greater than 50% with a minimum of stress on the main switching element. This converter, commonly called the BED Converter, is compared to the conventional single-ended and pushpull converters.

Control method for an extra high voltage d-c transmission connecting two three-phase networks

Abstract: Simultaneous power and voltage control by a d-c-tie between a-c networks is carried out by means of fixed and switchable inductive and capacitive compensation elements including the tap changer of both converter transformers of a d-c-tie for setting the optimum operating point by a transformation ratio of the converter transformer taps matching the primary current ratio, of the converter transformer taps for the maximally permissible stage of the one converter transformer, taking into consideration control, extinction and overlap angles of the d-c-tie.

Dual-slope analog-to-digital converter with voltage to current converter

Abstract: An analog-to-digital converter is provided based on supplying various multiplexed inputs, including analog input signal samples, to a voltage-to-current converter charging and discharging an integrated capacitor. A comparator determines the status of this capacitor to a control counter to provide digital representations.

Demagnetization circuit for forward converter

Abstract: A demagnetization circuit for use with a forward converter includes a drive winding magnetically coupled to the primary winding of the forward converter, a capacitor for absorbing leakage and magnetization energies from the primary winding when the forward converter is switched off, an inductor for absorbing energy from the capacitor, and a switching circuit for selectively connecting the inductor to the input voltage source of the forward converter.

A multiinput type converter for an uninterruptible dc power supply

Abstract: Low-power uninterruptible dc power supplies have been used widely. These are powered by several types of power sources with differing voltages, e.g., commercial ac power sources as well as batteries. A multi-input-type converter is developed to simplify circuit configuration and realize a low-loss power system. This paper presents a method of designing a multiinput transformer as well as the operation principle of a multiinput-type uninterruptible power supply and the circuit technology required for it. The power supply can be realized if the transformer primary winding-turn ratio is designed considering the input voltage variation range and the voltage-drop in the transformer primary circuit. The fact that the switching-duty ratio must be changed drastically and that the switching transistor loss is inclined to increase in a multiinput-type converter causes some problems. It is shown that the application of a collector current proportional drive circuit to the forward-type converter or a base resistor switching circuit to the flyback-type converter is effective in reducing the converter loss and the converter can be simplified by using most of the converter circuits in common.

Voltage/frequency converter with frequency drift compensation loop

Abstract: A voltage/frequency converter is formed of a V/F converter circuit which converts an input potential into a frequency corresponding to the instantaneous value of the input potential, and a difference detection circuit which generates an output corresponding to the difference between the output frequency of the V/F converter circuit and a predetermined reference frequency. The V/F converter circuit is controlled according to the level of the output from the difference detection circuit, thereby reducing the deviation of the output frequency of said V/F converter circuit from the reference frequency.

Controller of pwm power converter

Abstract: PURPOSE: To obtain a relatively large output in a PWM power converter of a relatively small capacity, by a method wherein when control variable of the PWM power converter comes close to limit value relating to modulation factor, a decrease in power factor is allowed. CONSTITUTION: A converter 1 controls DC voltage E d to constant value. An inverter 4 performs control in constant torque, constant power and characteristic range corresponding to speed of an electric car by an inverter controller 20. In order that modulation factor command MI to the converter 1 does not exceed the maximum modulation factor MI m , real axis component being the output of a phase controller 15 is restricted by an output PFL of a power factor limiter 19. Thereby, decrease of power factor is allowed and converter input voltage is controlled to a value to satisfy the maximum modulation factor. COPYRIGHT: (C)1987,JPO&Japio

A Low-Power Constant-Current Converter with HIC Techniques and its Circuit Simplification

Abstract: A low-power constant-current converter that is required to be small and inexpensive, is developed. The most effective means for size and cost reduction is to introduce hybrid IC (HIC) techniques and to mount as large a number of circuit elements as possible on the HIC substrate. Application of a circuit with a simple configuration is important for the HIC techniques. A flyback type converter that has a small number of parts is utilized, and circuit simplification techniques are developed. The driving transformer for isolation between the input and output in the control loop is replaced by a photocoupler, and the power supply for the transformer secondary circuit is improved to miniaturize the converter. A control circuit to compensate for phase-lag in the photocoupler is studied and a simple method is proposed. Both a method for simplifying the circuits and the analysis and design of the phase-compensation circuit for the constant-current converter are described. The converter is miniaturized to 9.2 cm3/W by application of the HIC technique. The size of the converter corresponding to one subscriber can be reduced to 1/5 compared with that of the conventional multi-output converter.