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WO1982001627A1 - High voltage high frequency dc-dc power supply - Google Patents

High voltage high frequency dc-dc power supply Download PDF

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Publication number
WO1982001627A1
WO1982001627A1 PCT/US1981/000443 US8100443W WO8201627A1 WO 1982001627 A1 WO1982001627 A1 WO 1982001627A1 US 8100443 W US8100443 W US 8100443W WO 8201627 A1 WO8201627 A1 WO 8201627A1
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WIPO (PCT)
Prior art keywords
power supply
winding
voltage
supply according
transformer
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
PCT/US1981/000443
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French (fr)
Inventor
Corp Unitron
Andrew Zadereji
George Zaderej
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Individual
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Individual
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Priority to AU72977/81A priority Critical patent/AU7297781A/en
Publication of WO1982001627A1 publication Critical patent/WO1982001627A1/en
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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/40—Means for preventing magnetic saturation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/338—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement

Definitions

  • the present invention relates generally to power supplies, and more particularly to a switching power supply operating at a relatively high frequency for converting a relatively low DC voltage to a high voltage symmetrical AC output.
  • the power supply finds particular utility for use in ignition systems for oil and gas-fired burners, electrostatic precipitator air cleaners, photocopy machines, television sets, fluorescent light ballast, and the like.
  • a relatively low DC voltage produced from an alternating line voltage is applied to a modified blocking oscillator formed by a single high voltage high frequency bipolar transistor biased for operation substantially in the active region and a high frequency ferrite core transformer having a main winding, and return, EMF and secondary windings coupled to the main winding.
  • the transistor is operated in the common emitter mode s ⁇ ch that the main winding is connected between the collector terminal and the low voltage DC source.
  • the return winding is connected in phase with the main winding between ground and the base terminal of the transistor by way of a serially connected blocking capacitor and resistor means.
  • the resistor means are selected to provide a substantially symmetrical alternating waveform at the secondary winding of the transformer.
  • the EMF winding is connected out of phase with the main winding in series with a high voltage fast recovery diode between the DC source and ground for absorbing energy stored in the transformer during negative excursions of the transformer output, in order to prevent permanent magnetization of the transformer core and protect the bipolar transistor from excessive voltage.
  • the transformer is particularly adapted for high frequency operation, with the main and back EMF windings being universally wound in a bifilar or twisted manner to maximize coupling and reduce inter-winding capacitance.
  • the transformer core includes an air gap which may be utilized in conjunction with the resistor means to set the frequency of oscillation of the oscillator portion of the power supply, as well as control the symmetrical shape of the output waveform.
  • the power supply operates in the range of 10-100 KHz
  • the physical size of the power supply may be significantly reduced.
  • the relatively high operating frequency, as well as the high duty cycle of the oscillator portion of the power supply minimize power losses, thereby enabling the supply to operate more efficiently.
  • output voltages in the range of 10 Kv. may be easily achieved. Further features of the invention will become apparent from the detailed description which follows.
  • FIG. 1 is a schematic diagram illustrating a first embodimentof the power supply of the present invention.
  • Fig. 2 is a schematic diagram illustrating a second embodiment of the power supply of the present invention.
  • Fig. 3 is a somewhat diagrammatic cross sectional view, partially cutaway, of the high frequency transformer used in the power supply of the present invention.
  • Fig. 4 is an enlarged fragmentary diagrammatic view of an alternate main and back EMF winding arrangement for use in the transformer illustrated in Fig. 3.
  • Fig. 5 is a fragmentary cross sectional view of the left-hand portion of the transformer of Fig. 3 utilizing the alternate winding arrangement of Fig. 4. DETAILED DESCRIPTION .
  • a first embodiment of the power supply of the present invention is illustrated schematically, generally at 1, in Fig. 1.
  • Line voltage of 120 VAC is applied to input terminals 2 and 3, and halfwave rectified by diode 10.
  • the rectified voltage is applied through surge resistor 12 to filter capacitor 14 to provide a source on line 15 of relatively low DC voltage.
  • the voltage appearing on line 15 will be of the order of 170 volts.
  • the portion of the circuitry illustrated in Fig. 1 connected to supply line 15 forms a modified blocking oscillator utilizing a forward converter.
  • a high voltage, high frequency PNP bipolar transistor 24, such as type number MJE 13004 manufactured by Motorola, Inc., is connected in the common emitter configuration with the emitter terminal grounded.
  • transistor 24 will have a collector-emitter breakdown voltage of several hundred volts, and at least 400 volts for the embodiment illustrated.
  • Transistor 24 is biased for operation substantially in the active region by means of biasing means formed by serially connected resistors 16 and 18 connected between DC supply line 15 and ground.
  • resistor 16 may be 100 K ⁇
  • resistor 18 may be 3K ⁇ to supply the bias current to the base terminal of transistor 24 connected to the junction of the resistors.
  • a high voltage diode 26 may be connected between the base terminal of the transistor and ground to protect the base emitter junction from negative voltage excursions.
  • resistor means 20 An impedance formed by serially connected resistor means 20 and blocking capacitor 22 is connected to the base terminal of transistor 24.
  • Capacitor 22 may be of the order of 0.1 ⁇ f, while resistor means 20 may be approximately 5K ⁇ for the embodiment illustrated in Fig. 1.
  • resistor means 20 will be adjusted to provide a substantially symmetrical alternating waveform at the output of the transformer secondary.
  • Power supply 1 also includes a high frequency transformer 30 including a main winding 32, a return winding 34, a back EMF winding 36, and one or more secondary windings 38.
  • Main winding 32 is connected between the collector terminal of transistor 24 and DC supply line 15.
  • Return winding 34 is coupled in phase with main winding 32 and is connected between ground and the free terminal of resistor means 20.
  • Back EMF winding 36 is coupled out of phase with main winding 32 and is connected serially with a diode 28 between ground and DC supply line 15.
  • diode 28 will be of the high voltage fast recovery type having a small t rr of 200 nanoseconds or less , such as type number GI RGP-10H manufactured by General Instruments Corp .
  • the winding ratio- between main winding 32. return winding 34, and back EMF winding 36 may be 10:1:10, respectively. In any event, the winding ratio between main winding 32 and return winding 34 will be at least 4:1. It will be observed that back EMF winding 36 together with diode 28 limit the voltage to transistor 24 to approximately twice the voltage appearing across capacitor 14. This not only enables the use of a transistor having lower breakdown voltages, but also prevents transformer 30 from going to saturation, with resulting lower losses, resulting in improved circuit efficiency.
  • Transformer 31 also includes four serially connected secondary windings 38 connected in phase with main winding 32.
  • the winding ratio between the secondary windings and the primary windings will be such as to produce the desired output voltage, which in the present case will nominally be in the range of 10Kv.
  • the physical construction of transformer 30 will be discussed in more detail hereinafter.
  • the high voltage appearing at the output of the transformer secondary is half wave rectified by diode 42 and filtered by filter capacitor 44 to produce the required DC high voltage at output terminals 45 and 46.
  • transformer 30 The construction of transformer 30 is illustrated generally in Fig. 3.
  • the transformer includes a core 40 generally of the double-U, CI or UI type, having a pair of spaced arms 40a and 40b for accepting primary windings 32, 34 and 36, and secondary windings 38, respectively.
  • Core 40 may be constructed of a ferrite material permitting high frequency operation in the range of 10-100 KHz.
  • the construction of core 40 should be such as to permit a flux density of 2000 gauss.
  • a Stackpole core number 15-9 of 24B grade has been found to produce satisfactory results.
  • Core 40 may also be provided with one or more air gaps 43 of the order of 0.020-0.040 inches which serve to increase the inductance of the transformer and contribute to better regulation of the power supply.
  • the frequency of oscillation of the oscillator section of the power supply may be varied by adjusting the length of air gap 43.
  • a plurality of air gaps may be utilized at spaced locations in core 40.
  • return winding 34 is wound closest to the core 40 on leg 40a, and will generally be wound in such a way as to cover the entire traverse.
  • Litz wire may be used for the return winding.
  • Secondary windings 38 are provided in several segments to reduce capacitive effects as well as increase the space factor to permit high voltage operation.
  • the segmental windings comprising secondary 38 are wound about leg 40b of core 40 using Litz wire to reduce the skin affect, in a universal wound pattern.
  • the angular displacement between successive layers should be as high as possible, and preferrably in the range of 60°-70° to permit operation at ' higher voltage and frequency levels.
  • each of the wires may be coated with polyurethane or the like to further reduce capacitive affect.s.
  • FIG. 2 A second embodiment of the present invention is illustrated in Fig. 2 where all of elements corresponding to those in the embodiment of Fig. 1 have been similarly designated. It will be observed that in this embodiment, the half-wave rectifier diode 10 of the embodiment of Fig.
  • transformer 30 will be such as to minimize, as far as possible, the capacitive effects . Consequently, the frequency of osc illation and the shape of ' the output waveform, which will be symmetrical and sinusoidal-like in shape, will be determined by the inductance presented by the transformer and the resistance governing the operating characteristics of transformer 24.
  • the inductance may be controlled by the width of air gap 43, which may be adjusted to provide a frequency of oscillation in the range of 50 KHz.
  • the value of resistor means 20 will be adjusted to also control the frequency of oscillation, as well as insure that both transistor 24 and transformer 30 are operated to prevent hard saturation of the transistor and transformer, respectively. This may be accomplished by setting the value of resistor means 20 in accordance with the nominal value of the expected load to be driven by the power supply.
  • the high frequency operation of the power supply of the present invention permits more efficient operation and the use of a power supply package of much smaller size. Furthermore, the efficient operation of the power supply reduces losses, thereby contributing to more efficient and energy conscious operation. In addition, the power supply requires only a single bipolar transistor, thereby greatly reducing the material and fabrication costs. It will be further understood that various changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

Une alimentation continu-continu utilise un oscillateur de blocage pour convertir une basse tension continue en une tension alternative elevee. Un transistor (24) est polarise par un diviseur de tension (16, 18). Un transformateur a haute frequence (30) comprend un enroulement (36EMF) posterieur couple en dephasage par rapport aux enroulements principal (32) et de retour (34). La tension elevee alternative a la sortie des enroulements secondaires segmentes (38) est redressee par une diode (42) ou appliquee a un doubleur de tension. L'enroulement EMF posterieur (36) et une diode (28) du type a retablissement rapide permettent l'utilisation d'un transistor (24) presentant une tension de claquage plus faible et empeche la saturation du transformateur (30). Les enroulements principal (32) et EMF posterieur (36) sont fabriques avec du fil de Litz et sont enroules dans une disposition bifilaire ou tordus. La largeur d'une couche d'air determine la frequence d'oscillation et la forme sinusoidale de la forme d'onde de courant alternatif. Cette alimentation est indiquee dans des systemes d'allumage pour des bruleurs a huile ou a gaz, dans des appareils electrostatiques de precipitation, dans des machines a photocopier ainsi que dans des postes de television et des ballasts de lumiere fluorescente.A DC-DC power supply uses a blocking oscillator to convert a low DC voltage into a high AC voltage. A transistor (24) is biased by a voltage divider (16, 18). A high frequency transformer (30) comprises a rear winding (36EMF) torque out of phase with respect to the main windings (32) and return (34). The high alternating voltage at the output of the segmented secondary windings (38) is rectified by a diode (42) or applied to a voltage doubler. The rear EMF winding (36) and a fast recovery type diode (28) allow the use of a transistor (24) having a lower breakdown voltage and prevents saturation of the transformer (30). The main windings (32) and posterior EMF (36) are made with Litz wire and are wound in a two-wire or twisted arrangement. The width of an air layer determines the frequency of oscillation and the sinusoidal shape of the AC waveform. This power is indicated in ignition systems for oil or gas burners, in electrostatic precipitation devices, in photocopying machines as well as in television sets and fluorescent light ballasts.

Description

HIGH VOLTAGE HIGH FREQUENCY DC-DC POWER SUPPLY SUMMARY OF THE INVENTION This application is a continuation-in-part of Serial No. 8,181 filed January 30, 1979, for "High Frequency Battery Charger".
The present invention relates generally to power supplies, and more particularly to a switching power supply operating at a relatively high frequency for converting a relatively low DC voltage to a high voltage symmetrical AC output. The power supply finds particular utility for use in ignition systems for oil and gas-fired burners, electrostatic precipitator air cleaners, photocopy machines, television sets, fluorescent light ballast, and the like.
In a preferred embodiment, a relatively low DC voltage produced from an alternating line voltage is applied to a modified blocking oscillator formed by a single high voltage high frequency bipolar transistor biased for operation substantially in the active region and a high frequency ferrite core transformer having a main winding, and return, EMF and secondary windings coupled to the main winding. The transistor is operated in the common emitter mode sμch that the main winding is connected between the collector terminal and the low voltage DC source. The return winding is connected in phase with the main winding between ground and the base terminal of the transistor by way of a serially connected blocking capacitor and resistor means. As will be explained in more detail hereinafter, the resistor means are selected to provide a substantially symmetrical alternating waveform at the secondary winding of the transformer. The EMF winding is connected out of phase with the main winding in series with a high voltage fast recovery diode between the DC source and ground for absorbing energy stored in the transformer during negative excursions of the transformer output, in order to prevent permanent magnetization of the transformer core and protect the bipolar transistor from excessive voltage.
The transformer is particularly adapted for high frequency operation, with the main and back EMF windings being universally wound in a bifilar or twisted manner to maximize coupling and reduce inter-winding capacitance. The transformer core includes an air gap which may be utilized in conjunction with the resistor means to set the frequency of oscillation of the oscillator portion of the power supply, as well as control the symmetrical shape of the output waveform. Inasmuch as the power supply operates in the range of 10-100 KHz, the physical size of the power supply may be significantly reduced. Furthe more, the relatively high operating frequency, as well as the high duty cycle of the oscillator portion of the power supply, minimize power losses, thereby enabling the supply to operate more efficiently. By proper choice of the transformer secondary configuration, output voltages in the range of 10 Kv. may be easily achieved. Further features of the invention will become apparent from the detailed description which follows.
BRIEF DESCRIPTION OF THE DRAWING Fig. 1 is a schematic diagram illustrating a first embodimentof the power supply of the present invention. Fig. 2 is a schematic diagram illustrating a second embodiment of the power supply of the present invention. Fig. 3 is a somewhat diagrammatic cross sectional view, partially cutaway, of the high frequency transformer used in the power supply of the present invention.
Fig. 4 is an enlarged fragmentary diagrammatic view of an alternate main and back EMF winding arrangement for use in the transformer illustrated in Fig. 3.
Fig. 5 is a fragmentary cross sectional view of the left-hand portion of the transformer of Fig. 3 utilizing the alternate winding arrangement of Fig. 4. DETAILED DESCRIPTION .
A first embodiment of the power supply of the present invention is illustrated schematically, generally at 1, in Fig. 1. Line voltage of 120 VAC is applied to input terminals 2 and 3, and halfwave rectified by diode 10. The rectified voltage is applied through surge resistor 12 to filter capacitor 14 to provide a source on line 15 of relatively low DC voltage. In the embodiment illustrated the voltage appearing on line 15 will be of the order of 170 volts. The portion of the circuitry illustrated in Fig. 1 connected to supply line 15 forms a modified blocking oscillator utilizing a forward converter. A high voltage, high frequency PNP bipolar transistor 24, such as type number MJE 13004 manufactured by Motorola, Inc., is connected in the common emitter configuration with the emitter terminal grounded. In general, transistor 24 will have a collector-emitter breakdown voltage of several hundred volts, and at least 400 volts for the embodiment illustrated. Transistor 24 is biased for operation substantially in the active region by means of biasing means formed by serially connected resistors 16 and 18 connected between DC supply line 15 and ground. For purposes of an exemplary showing, resistor 16 may be 100 KΩ, and resistor 18 may be 3KΩ to supply the bias current to the base terminal of transistor 24 connected to the junction of the resistors. A high voltage diode 26 may be connected between the base terminal of the transistor and ground to protect the base emitter junction from negative voltage excursions.
An impedance formed by serially connected resistor means 20 and blocking capacitor 22 is connected to the base terminal of transistor 24. Capacitor 22 may be of the order of 0.1 μf, while resistor means 20 may be approximately 5KΩ for the embodiment illustrated in Fig. 1. As will be explained in more detail hereinafter, resistor means 20 will be adjusted to provide a substantially symmetrical alternating waveform at the output of the transformer secondary.
Power supply 1 also includes a high frequency transformer 30 including a main winding 32, a return winding 34, a back EMF winding 36, and one or more secondary windings 38. Main winding 32 is connected between the collector terminal of transistor 24 and DC supply line 15. Return winding 34 is coupled in phase with main winding 32 and is connected between ground and the free terminal of resistor means 20. Back EMF winding 36 is coupled out of phase with main winding 32 and is connected serially with a diode 28 between ground and DC supply line 15. In general, diode 28 will be of the high voltage fast recovery type having a small trr of 200 nanoseconds or less , such as type number GI RGP-10H manufactured by General Instruments Corp . For purposes of an exemplary showing, the winding ratio- between main winding 32. return winding 34, and back EMF winding 36 may be 10:1:10, respectively. In any event, the winding ratio between main winding 32 and return winding 34 will be at least 4:1. It will be observed that back EMF winding 36 together with diode 28 limit the voltage to transistor 24 to approximately twice the voltage appearing across capacitor 14. This not only enables the use of a transistor having lower breakdown voltages, but also prevents transformer 30 from going to saturation, with resulting lower losses, resulting in improved circuit efficiency.
Transformer 31 also includes four serially connected secondary windings 38 connected in phase with main winding 32. The winding ratio between the secondary windings and the primary windings will be such as to produce the desired output voltage, which in the present case will nominally be in the range of 10Kv. The physical construction of transformer 30 will be discussed in more detail hereinafter. The high voltage appearing at the output of the transformer secondary is half wave rectified by diode 42 and filtered by filter capacitor 44 to produce the required DC high voltage at output terminals 45 and 46.
The construction of transformer 30 is illustrated generally in Fig. 3. The transformer includes a core 40 generally of the double-U, CI or UI type, having a pair of spaced arms 40a and 40b for accepting primary windings 32, 34 and 36, and secondary windings 38, respectively. Core 40 may be constructed of a ferrite material permitting high frequency operation in the range of 10-100 KHz. In addition, the construction of core 40 should be such as to permit a flux density of 2000 gauss. For this purpose, a Stackpole core number 15-9 of 24B grade has been found to produce satisfactory results. Core 40 may also be provided with one or more air gaps 43 of the order of 0.020-0.040 inches which serve to increase the inductance of the transformer and contribute to better regulation of the power supply. In addition, the frequency of oscillation of the oscillator section of the power supply, as well as the symmetrical characteristics of the output voltage, may be varied by adjusting the length of air gap 43. If desired, a plurality of air gaps may be utilized at spaced locations in core 40. As best shown in Fig. 3, return winding 34 is wound closest to the core 40 on leg 40a, and will generally be wound in such a way as to cover the entire traverse. In order to reduce the skin effect at high frequencies, Litz wire may be used for the return winding. In a preferred embodiment, main winding 32 and back
EMF winding 36 are precision wound in a bifilar arrangement to reduce intercoupling capacitance and maximize the coupling coefficient. Furthermore, it is preferred that one or both of windings 32 and 36 be fabricated from Litz wire to further reduce capacitive effects. An alternate winding arrangement is illustrated in Fig. 4 where back EMF winding 36 is tightly twisted with main winding 32 at the rate of approximately two twists per inch to achieve the same affect. The composite winding is then wound over return winding 34 on leg 40a of core 40 as illustrated in Fig. 5.
Secondary windings 38 are provided in several segments to reduce capacitive effects as well as increase the space factor to permit high voltage operation. The segmental windings comprising secondary 38 are wound about leg 40b of core 40 using Litz wire to reduce the skin affect, in a universal wound pattern. In general, the angular displacement between successive layers should be as high as possible, and preferrably in the range of 60°-70° to permit operation at 'higher voltage and frequency levels. In addition, to reduce inter-winding
__ - ----¬
SUBSTITUTE SHEET L Q_- .FI coupling between the windings of a particular segment, each of the wires may be coated with polyurethane or the like to further reduce capacitive affect.s. Flanges 39 spaced from the core legs connecting arms 40a and 40b as well as from the adjacent segments, serve to eliminate corona effects at the higher voltage levels. It will be understood that the winding ratio between secondary windings 38 and the primary windings will be such as to create the desired high voltage output from the power supply. A second embodiment of the present invention is illustrated in Fig. 2 where all of elements corresponding to those in the embodiment of Fig. 1 have been similarly designated. It will be observed that in this embodiment, the half-wave rectifier diode 10 of the embodiment of Fig. 1 has been replaced by a full wave bridge voltage doubler 52 for producing a DC voltage on lines 15. Consequently, the voltages applied to the primary of transformer 30 are higher than in the embodiment described hereinabove. In addition, to further increase the output voltage, the secondary winding ,of transformer 30 is connected to. a cascade voltage multiplier 50 for providing the high voltage output at terminals 45 and 46 of power supply 1. In all other respects, the operation of the circuit is similar to that described, hereinabove. In operation, the frequency of oscillation of power supply 1, as well as the shape of the output waveform will be determined to a large extent by the effective resistance, capacitance and inductance viewed in the primary or oscillator portion of the circuit. As noted above, the construction of transformer 30 will be such as to minimize, as far as possible, the capacitive effects . Consequently, the frequency of osc illation and the shape of' the output waveform, which will be symmetrical and sinusoidal-like in shape, will be determined by the inductance presented by the transformer and the resistance governing the operating characteristics of transformer 24. In general, the inductance may be controlled by the width of air gap 43, which may be adjusted to provide a frequency of oscillation in the range of 50 KHz. In addition, the value of resistor means 20 will be adjusted to also control the frequency of oscillation, as well as insure that both transistor 24 and transformer 30 are operated to prevent hard saturation of the transistor and transformer, respectively. This may be accomplished by setting the value of resistor means 20 in accordance with the nominal value of the expected load to be driven by the power supply.
It has been found that the high frequency operation of the power supply of the present invention permits more efficient operation and the use of a power supply package of much smaller size. Furthermore, the efficient operation of the power supply reduces losses, thereby contributing to more efficient and energy conscious operation. In addition, the power supply requires only a single bipolar transistor, thereby greatly reducing the material and fabrication costs. It will be further understood that various changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are as follows:
1. A single ciansistor high voltage power supply for converting a source of rela tively low DC voltage to a high voltage high frequency alternating voltage comprising: a bipolar transistor having emitter, base and collector terminals, said emitter terminal being connected to ground; means for biasing said base terminal of the transistor for operation substantially in the active region; a transformer having a main winding, and return, back EMF and secondary windings coupled to said main winding; a blocking capacitor connected to the base terminal of the transistor; resistor means connected between said capacitor and said return winding, said return winding being wound in phase with said main winding, said resistor means being selected to provide a substantially symmetrical alternating waveform at the secondary winding of the transformer; and a diode serially connected with said back EMF winding between the DC source and ground for absorbing energy stored in said transformer to prevent permanent magnetization of the transformer core and protect the transformer from excessive voltage excursions
2. The power supply according to claim 1 including input means for producing said relatively low DC voltage from an alternating voltage line input.
3. The power supply according to claim 2 wherein said input means includes a voltage doubler.
4. The power supply according to claim 1 wherein said transistor has a collector-emitter breakdown voltage of at least 400 volts.
5. The power supply according to claim 1 wherein said biasing means comprises a pair of resistors connected between said low DC voltage and ground, the base terminal of the transistor being connected to the junction of the resistors.
6. The power supply according to claim 1 wherein the winding ratio between said main and return winding is at least 4:1.
7. The power supply according to claim 6 wherein the winding ratio between said main and return winding is. about 10:1.
8. The power supply according to claim 1 wherein the winding ratio between said main and back-EMF windings is about 1:1.
9. The power supply according to claim 1 wherein the operating frequency of said power supply is in the range of about 10-100 KHz.
10. The power supply according to claim 9 wherein the operating frequency of said power supply is at least about 30 KHz.
11. The power supply according to claim 1 wherein the winding ratio of said second any winding is such as to produce an unloaded output voltage of about 10 Kv.
12. The power supply according to claim 1 wherein said diode is of a High voltage fast recovery type having a reverse recovery time of no less than 200 ns.
13. The power supply according to claim 1 wherein the anode of the diode is connected to ground and the back EMF winding is connected out of phase with said main winding between the cathode of the diode and the DC voltage input.
14. The power supply according to claim 1 wherein said transistor and said transformer are operated out of saturation.
15. The power supply according to claim 1 wherein one at least of said main and back EMF windings is fabricated from Litz wire.
16. The power supply according to claim 1 wherein said main and back EMF windings are wound in bifilar relationship.
17. The power supply according to claim 1 wherein said main and back EMF windings are twisted together.
18. The power supply according to claim 17 wherein said main and back EMF windings are twisted together at the rate of about two twists per inch.
19. The power supply according to claim 1 wherein said main and back EMF windings are universal wound.
20. The power supply according to claim 19 wherein the angular displacement between successive layers of said universally wound windings is at least 60°.
21. The power supply according to .claim 1 wherein said transformer includes a core, said return winding being wound first on the core.
22. The power supply according to claim 21 wherein said core is fabricated from a ferrite material for high frequency operation.
23. The power supply according to claim 21 wherein said core includes at least one air gap for adjusting the frequency of oscillation of the power supply.
24. The power supply according to claim 1 including a voltage doubler connected to said secondary winding.
25. A single transistor high voltage power supply for converting a source of relatively low DC voltage to a high voltage high frequency alternating voltage comprising: input means for producing said relatively low
DC voltage from an alternating voltage line input; a high voltage bipolar transistor having emitter, base and collector terminals, said emitter terminal being connected to ground; means for biasing said base terminal of the transistor such that the transistor operates substantially out of saturation, said biasing means comprising a pair of resistors connected between said low DC voltage and ground, the base terminal of the transistor being connected to the junction of the resistors; a transformer having a main winding, and return, back EMF and secondary windings coupled to said main winding, said main and return windings having a winding ratio of at least 4:1, said secondary winding having a winding ratio such as to produce an unloaded output voltage of several Kv., said transformer being operated substantially out of saturation, at least one of said main and back EMF windings being fabricated of Litz wire and being wound so as to reduce inter-winding capacitance effects, said transformer including a ferrite core having an air gap for adjusting the frequency of oscillation of the power supply, said return winding being wound closest to said core; a blocking capacitor connected to the base terminal of the transistor; resistor means connected between said capacitor and said return winding, said return winding being wound in phase with said main winding, said resistor means being selected to provide a substantially symmetrical sinusoidal- like alternating waveform at the secondary winding of the transformer and an operating frequency in the range of about 10-100 KHz; and a high voltage fast recovery diode serially connected with said back EMF winding between the DC source and ground for absorbing energy stored in said transformer to prevent permanent magnetization of the transformer core and protect the transistor from excessive voltage excursions, the anode of the diode being connected to ground, the back EMF winding being connected out of phase with said main winding between the cathodeof the diode and the low DC voltage.
26. The power supply according to claim 25 wherein said power supply is operated at a frequency of at least about 30 KHz.
27. The power supply according to claim 26 wherein said main and back EMF windings are twisted together.
28. The power supply according to claim 27 wherein said input means includes a voltage doubler, and including a voltage doubler connected to the secondary of the transformer.
PCT/US1981/000443 1980-10-30 1981-04-06 High voltage high frequency dc-dc power supply Ceased WO1982001627A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU72977/81A AU7297781A (en) 1980-10-30 1981-04-06 High voltage high frequency dc-dc power supply

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US20236680A 1980-10-30 1980-10-30
US202366801030 1980-10-30

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4607319A (en) * 1982-03-25 1986-08-19 Telefonaktiebolaget Lm Ericsson Flyback DC/DC converter with low ripple in the output capacitor
US4651264A (en) * 1984-09-05 1987-03-17 Trion, Inc. Power supply with arcing control and automatic overload protection
US4654771A (en) * 1984-08-07 1987-03-31 Siemens Aktiengesellschaft Switched power supply comprising a free-running flow converter and electrically separated control loop
US4660133A (en) * 1984-08-07 1987-04-21 Siemens Aktiengesellschaft Switched power pack with free-wheeling flow converter and switched controller at a secondary side
US4745535A (en) * 1986-03-14 1988-05-17 Mitsubishi Denki Kabushiki Kaisha Ringing choke type DC/DC converter
FR2685145A1 (en) * 1991-12-13 1993-06-18 Sextant Avionique Overvoltage clipping device for a resonance-type power supply converter
EP0824041A3 (en) * 1996-08-14 1999-03-31 Wein Products, Inc. Portable personal corona discharge device for destruction of airborne microbes and chemical toxins
EP0932248A1 (en) * 1998-01-22 1999-07-28 Rosemary Ann Ainslie Method of harnessing a back-emf, and apparatus used in performing the method.
WO1999038247A1 (en) * 1998-01-22 1999-07-29 Ashby, Kevin, Peter Harnessing a back emf
US10692646B2 (en) * 2017-07-19 2020-06-23 Toyota Motor Engineering & Manufacturing North America, Inc. Single litz wire transformers

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US1882128A (en) * 1927-06-01 1932-10-11 Edward W Fearing Radiofrequency amplification system
US2791739A (en) * 1954-05-20 1957-05-07 Philips Corp Circuit arrangement for converting a lower d. c. voltage into a higher d. c. voltage
US2920259A (en) * 1956-01-27 1960-01-05 Philips Corp Direct current converter
US3064177A (en) * 1955-06-29 1962-11-13 Universal Transistor Products Transistorized power supply
FR1364696A (en) * 1963-05-13 1964-06-26 Radiotechnique DC voltage converter
US3247422A (en) * 1961-06-01 1966-04-19 Gen Electric Transistor inverter ballasting circuit
US3377582A (en) * 1964-08-21 1968-04-09 Elastic Stop Nut Corp Magnetic toroidal core having successive windings with the pair of lead ends of eachwinding spaced from the pair of lead ends of each other winding
DE2749847A1 (en) * 1977-11-08 1979-05-10 Licentia Gmbh Switched power supply for TV receiver - has transformer feedback winding with coupling to secondary windings chosen so that voltage on one is constant with load changes on other
US4183080A (en) * 1978-06-21 1980-01-08 Theodore Liebman DC to DC converter
EP0018186A1 (en) * 1979-04-12 1980-10-29 Gould Advance Limited Improved inverter circuit

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US1882128A (en) * 1927-06-01 1932-10-11 Edward W Fearing Radiofrequency amplification system
US2791739A (en) * 1954-05-20 1957-05-07 Philips Corp Circuit arrangement for converting a lower d. c. voltage into a higher d. c. voltage
US3064177A (en) * 1955-06-29 1962-11-13 Universal Transistor Products Transistorized power supply
US2920259A (en) * 1956-01-27 1960-01-05 Philips Corp Direct current converter
US3247422A (en) * 1961-06-01 1966-04-19 Gen Electric Transistor inverter ballasting circuit
FR1364696A (en) * 1963-05-13 1964-06-26 Radiotechnique DC voltage converter
US3377582A (en) * 1964-08-21 1968-04-09 Elastic Stop Nut Corp Magnetic toroidal core having successive windings with the pair of lead ends of eachwinding spaced from the pair of lead ends of each other winding
DE2749847A1 (en) * 1977-11-08 1979-05-10 Licentia Gmbh Switched power supply for TV receiver - has transformer feedback winding with coupling to secondary windings chosen so that voltage on one is constant with load changes on other
US4183080A (en) * 1978-06-21 1980-01-08 Theodore Liebman DC to DC converter
EP0018186A1 (en) * 1979-04-12 1980-10-29 Gould Advance Limited Improved inverter circuit

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4607319A (en) * 1982-03-25 1986-08-19 Telefonaktiebolaget Lm Ericsson Flyback DC/DC converter with low ripple in the output capacitor
US4654771A (en) * 1984-08-07 1987-03-31 Siemens Aktiengesellschaft Switched power supply comprising a free-running flow converter and electrically separated control loop
US4660133A (en) * 1984-08-07 1987-04-21 Siemens Aktiengesellschaft Switched power pack with free-wheeling flow converter and switched controller at a secondary side
US4651264A (en) * 1984-09-05 1987-03-17 Trion, Inc. Power supply with arcing control and automatic overload protection
US4745535A (en) * 1986-03-14 1988-05-17 Mitsubishi Denki Kabushiki Kaisha Ringing choke type DC/DC converter
GB2188498B (en) * 1986-03-14 1990-07-25 Mitsubishi Electric Corp Blocking oscillator type converter
FR2685145A1 (en) * 1991-12-13 1993-06-18 Sextant Avionique Overvoltage clipping device for a resonance-type power supply converter
EP0824041A3 (en) * 1996-08-14 1999-03-31 Wein Products, Inc. Portable personal corona discharge device for destruction of airborne microbes and chemical toxins
US6042637A (en) * 1996-08-14 2000-03-28 Weinberg; Stanley Corona discharge device for destruction of airborne microbes and chemical toxins
EP0932248A1 (en) * 1998-01-22 1999-07-28 Rosemary Ann Ainslie Method of harnessing a back-emf, and apparatus used in performing the method.
WO1999038247A1 (en) * 1998-01-22 1999-07-29 Ashby, Kevin, Peter Harnessing a back emf
US10692646B2 (en) * 2017-07-19 2020-06-23 Toyota Motor Engineering & Manufacturing North America, Inc. Single litz wire transformers

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