The set input S of the latch 20 is driven by a first voltage sensor 22 having its input coupled to the rectifier 16 output V I for sensing a first voltage level lower than the DC output voltage V O of the circuit, in this case a voltage of zero volts. The reset input R of the latch circuit 20 is coupled to the output of a second voltage sensor 24 which has its input coupled to the output terminal V O in order to sense the DC output voltage of the converter circuit, in this case, by way of example only, 15 volts.
A filter capacitor 26 is coupled to the output terminal V O in order to smooth the DC output voltage, and, in operation, a load 28 will be coupled to the output terminal V O to receive the DC output voltage generated by the converter circuit.
In this embodiment, the rectifier circuit 16 is a full-wave bridge rectifier circuit composed of diodes 30, 32, 34 and 36, although any other suitable form of rectifier circuit, such as a half-wave bridge circuit, may be employed. The switch 18 is shown here as a JFET 38, although other types of switches, such as a depletion-mode MOS transistor may alternatively be used.
The first voltage sensor 22 is realized by a high-voltage sensing diode 40, a diode 42 and a resistor 44, while the second voltage sensor 24 is composed of a zener diode 46, a resistor 48 and a current mirror composed of bipolar transistors 50 and The invention is not limited to the particular sensor configurations shown, and other suitable voltage sensors may be used instead.
In the circuit of FIG. Operation of the high-voltage AC to low-voltage DC converter circuit 10 will be explained with reference to the waveforms shown in FIG.
In FIG. Each time the waveform V I returns to approximately zero volts, the first voltage sensor, here a zero volt sensor, will detect this level and provide a set input S to the latch 20, causing its output V Q go high, as shown by waveform V Q at times t 1 , t 3 and t 5 in FIG. Subsequently, when rectifier output V I rises to the desired DC output voltage of the circuit, here 15 volts for illustration, the second voltage sensor 15 volt sensor 24 will reset latch 20, causing the voltage V Q to go low, as shown in FIG.
Since switch 18 is controlled by the voltage V Q , it will be apparent that this switch will be turned on at times t 1 , t 3 and t 5 , and turned off at times t 2 , t 4 and t 6 When switch 18 is on, between times t 1 and t 2 , t 3 and t 4 , and t 5 and t 6 , nodes V I and V O will be connected, and capacitor 26 will be charged to the voltage at node V I , as shown in FIG.
When the voltage V O on capacitor 26 reaches the desired DC output voltage, here 15 volts, sensor 24 will be activated, thus resetting latch 20 and opening switch This in turn will disconnect output terminal V O from V I , and the voltage V O will slowly decay from its maximum value with a time constant determined by capacitor 26 and load 28, until sensor 22 is reactivated by the next cycle, whereupon the latch 20 is again set and switch 18 is turned on, and the cycle is repeated.
Converter circuits in accordance with the present invention offer a number of important advantages. Unlike prior-art circuits which employ bulky transformers and several high-voltage components, the present invention employs no transformer and a minimum of high-voltage components, resulting in an economical, compact and more easily integrated device.
Furthermore, since nearly all of the control circuitry is powered from the DC output voltage V O , stable, highly-efficient control circuit operation is obtained.
Additionally, since the switch 18 is rendered conductive at the onset of each pulsating voltage cycle, at or near zero volts, and then turns off when the desired low DC output voltage is reached, conduction takes place only when the input voltage is low, unlike prior-art circuits in which the time at which the switch begins to conduct can vary greatly and conduction can take place when the input voltage is high, thus permitting the present circuit to operate in a stable, consistent and highly-efficient manner.
While the invention has been particularly shown and described with reference to several preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit or scope of the invention. Thus, for example, various different types of rectifier circuits or switches may be employed, and different voltage sensor and latch circuits can be substituted to satisfy particular design requirements.
All rights reserved. Login Sign up. Search Expert Search Quick Search. High-voltage AC to low-voltage DC converter. United States Patent A high-voltage AC to low-voltage DC converter includes a rectifier circuit for providing a pulsating high-voltage DC signal from the high-voltage AC input and a switch having its main current path coupled between the rectifier circuit output and an output terminal of the converter. A filter capacitor is coupled to the output terminal to filter the low-voltage DC output, and first and second voltage sensors are coupled to the rectifier output and the low-voltage DC output terminal of the converter circuit, respectively.
The first voltage sensor is set to sense a low typically zero voltage, and the second voltage sensor is set to sense the desired low-voltage DC output level.
The outputs of the first and second voltage sensors are coupled to the set and reset inputs, respectively, of a latch circuit, with the output of the latch circuit being coupled to a control terminal of the switch in order to turn on the switch upon receiving a set input from the first voltage sensor and then turn off the switch on receiving a reset input from the second voltage sensor.
This converter configuration provides a compact and highly-efficient circuit. The Figure 12 voltage converter is intended for use with 1. DC negative-voltage generator or voltage doubler using 1. The Figure 13 circuit is similar, but is meant for use with supplies in the 3.
DC negative-voltage generator or voltage doubler using 3. Finally, the Figure 14 circuit is meant for use with supplies in the range 6. DC negative-voltage generator or voltage doubler using 6. The presence of this diode reduces the available output voltage by Vdf, the forward volt drop of the diode; to keep this volt drop to minimum values, D1 should be a germanium or Schottky type.
A useful feature of the ICL is that numbers of these ICs up to a maximum of 10 can be cascaded to give voltage conversion factors greater than unity. Thus, if three stages are cascaded, they give a final negative output voltage of -3Vcc, etc. Figure 15 shows the connections for cascading two of these stages; any additional stages should be connected in the same way as the right-hand IC of this diagram. Cascading ICs for increased negative output voltage. It has already been pointed out that a single ICL IC can be used as a highly efficient voltage doubler that can, for example, generate a centre-tapped 10V output when powered from a single-ended 5V input.
Figure 16 shows how two of these ICs can be cascaded to generate a centre-tapped 12V output when the circuit is powered from a single-ended 3V source e. Cascaded ICs giving a centre-tapped 12V output from a 3V supply. Here, IC1 is used as a basic voltage doubler, powered from a 3V source connected between pins 3 and 8, and its 6V output from between pins 5 and 8 is used to power IC2 via pins 3 and 8, and IC2 thus generates an output between pins 5 and 8 of 12V when very lightly loaded.
This 12V output has a source impedance of about R, and falls by about 0. Another way of reducing the oscillator frequency is to use pin 7 to over-drive the oscillator via an external clock, as shown in Figure The clock signal must be fed to pin 7 via a 1K0 series resistor R1 , and should switch fully between the two supply rail values; in the diagram, a CMOS gate is wired as an inverting buffer stage, to ensure such switching.
So far, this article has described three of the four most widely used types of DC voltage conversion circuit. Diode-steered charge pump type of voltage doubler. The circuit action is very simple, as follows:. The Diodes , rectify the secondary AC into a pulsating DC, which is then filtered by inductor and capacitor The output inductor and capacitor filters the pulsating DC into an average value equal to the duty of the waveform times its amplitude.
The switches, , , , , , are typically semi-conductor devices that have a reverse diode across them to clamp any reverse voltage that may be generated by transformer during the time the SWITCH DRIVE changes state. The combination of the switches , , , , , capacitor , , and primary of transformer may be combined in any way shown in FIG. As used herein, the term high voltage DC refers generally to voltages greater than the intended high range tolerance voltage of a single semi-conductor switch used in the intended application.
For medium power applications, an exemplary lower limit of a range of high voltages might be V DC. The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto.
A high voltage DC to low voltage converter comprising a plurality of switches adapted to connect in series to a high voltage DC source, the switches operated in pairs as half bridges, each half bridge coupled through a plurality of capacitors to a primary of a transformer having an isolated secondary, which is rectified and filtered into low voltage power.
The high voltage DC to low voltage converter as in claim 1 , wherein the plurality of switches are paired, each pair of switches forming a half bridge and coupled through a capacitor to separate primaries of an isolation transformer with one or more secondaries rectified and filtered into a low voltage DC supply.
The high voltage DC to low voltage converter as in claim 1 , wherein the plurality of switches are paired, coupled through a capacitor to one side of a primary of an isolation transformer, and the other side of the primary coupled to another half bridge switch pair which is operated in opposite phase to the half bridge on the opposite side of the primary, thus forming a full bridge, of which there are one or more each with separate primaries of an isolation transformer with one or more isolated secondaries rectified and filtered into a low voltage supply.
The high voltage DC to low voltage converter as in claim 1 , where the plurality of switches are paired, each pair of switches forms a half bridge and is coupled through a capacitor to a common primary of a transformer which has one or more isolated secondaries rectified by diodes forming a rectified pulsing DC supply which is then filtered by an inductor and capacitor in to a low voltage DC supply which is substantially equal to the average of the pulsating DC input, and a control circuit that provides a feedback signal to a PWM MODULE that generates a pulse width modulated signal in relation to the feedback provided to a SWITCH DRIVER that turns the switches on and off with a time period governed by the PWM signal, and control electronics adapted to be powered by a START MODULE powered temporarily at starting by a start-up capacitor and after starting by an isolated secondary of the transformer.
The high voltage DC to low voltage converter as in claim 4 , wherein each half bridge is coupled through a capacitor to separate primaries of an isolation transformer. The high voltage DC to low voltage converter as in claim 4 , where each half bridge is coupled through a capacitor to one side of a primary of an isolation transformer and the other side of the primary is coupled through a capacitor to another half bridge switch pair operated in opposite phase to the half bridge on the opposite side of the primary, all forming a full bridge, with one or more full bridges in series, operated with each coupled and appropriately phased to a common primary of an isolation transformer.
The high voltage DC to low voltage converter as in claim 1 , which operates from a common high voltage distribution bus and is enabled on demand to convert available high voltage DC to low voltage power to operate a low voltage device. The high voltage DC to low voltage converter as in claim 1 , adapted to operate a solid state RF amplifier to replace a high voltage vacuum RF amplifying device. The high voltage DC to low voltage converter as in claim 1 , adapted to operate an electric motor.
The high voltage DC to low voltage converter as in claim 14 , wherein the electric motor is adapted to operate in a vehicle. The high voltage DC to low voltage converter as in claim 1 , adapted to convert the output of a high voltage battery to low voltage electricity upon demand. The high voltage DC to low voltage converter as in claim 1 , where the high voltage DC to low voltage converter is adapted to operate, on demand, a solid state laser module or subcomponents of a large solid state laser array.
The high voltage DC to low voltage converter as in claim 1 , adapted to operate a solid state RF amplifier as a replacement for a high voltage vacuum tube-type RF amplifying device.
The high voltage DC to low voltage converter as in claim 1 , adapted to operate an electric motor in a vehicle. The high voltage DC to low voltage converter as in claim 1 , adapted to convert the output of a high voltage battery to a low voltage power upon demand. USA1 en. Compact driver, notably for a light emitting diode, having an integrated dual output.
Power control system for periodically and selectively energizing or shorting primary windings of transformers for controlling the output voltage across a common secondary winding.
Full wave series resonant type DC to DC power converter with integrated magnetics. USB2 en. Compact driver, in particular, for light emitting diodes, having integrated dual output. USB1 en. Alexander topology resonance energy conversion and inversion circuit utilizing a series capacitance multi-voltage resonance section.
USA en. CNB en. Two-way step down-boost power converter, electric starter-generator system and method. AUB2 en. JPB2 en. CNC en. Method for generating output DC voltage and plasma processing DC voltage power supply. EPA1 en. EPB1 en.
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