CA1177157A - Television receiver ferroresonant load power supply - Google Patents

Abstract

RCA 75,752, ABSTRACT OF THE DISCLOSURE
To regulate a supply voltage for a television receiver load circuit, such as the ultor voltage for a high voltage circuit, the primary winding of a transformer is coupled to a source of alternating input voltage for developing an alternating polarity voltage across a secondary winding of the transformer. A saturable reactor includes a magnetizable core with a reactor winding wound around the core. The reactor winding and the transformer secondary winding are conductively coupled to develop an alternating polarity voltage across the reactor winding.
The transformer secondary winding is magnetically isolated from the saturable reactor such that the magnetic flux flowing in the reactor core does not link the transformer secondary winding. A capacitor is coupled to the saturable reactor winding for developing a circulating current that aids in magnetically saturating a portion of the reactor core associated with the reactor winding. The voltages across the conductively coupled transformer secondary winding are thereby regulated. The high voltage load circuit is coupled to a third winding of the transformer and is energized by the regulated alternating polarity supply voltage appearing across the third winding.

Description

7~

TELEVISION RECEIVER FERRORESONANT
I,OAD POWER SUPPLY

5This invention relates to ferroresonant television power supplies.
Ferroresonant transformers are known which provide regulated ultor voltages and regulated B+ scanning voltages for television receivers. A television receiver ferroresonant power supply is described in U.S. Patent 4,319,167, issued 9 March 1982 to F. S. Wendt, entitled "HIGH FREQUENCY FERRORESONANT POWER SURPLY FOR A
DEFLECTION AND HIGH VOLTAGE CIRCUIT", which corresponds to British Patent Application No. 2041668A, published September 10, 1980. When operated at a relatively high input frequency, such as at a horizontal deflection freuqency of 15.75 KHz, a ferroresonant transformer is a relatively compact and low weight unit which provides inherent output voltage regulation without the necessity of relatively --20 complex and expensive electronic regulator control circuitry.
To provide high efficiency at 16 KHz, the magnetizeable core of a ferroresonant transformer may be formed from a ferrite such as a commercially available manganese-zinc or nickel-zinc ferrite. Such ferrite materials exhibit a high resistance to current fiow, thereby incurring relatively small eddy current losses, which otherwise would be excessive at the relatively high 16 KHz operating frequency. Hysteresis losses are also relatively low. Even when using a ferrite core, however, I2R losses in one or more of the windings, eddy current losses, and hysteresis losses may produce a substantial rise in the core temperature.
The saturation flux density, Bsat. of amagnetizeable material decreases with increasing core temperature. For manganese-zinc ferrites, the saturation flux density may decrease from about 4.5 kilogauss at 20C to 2.5 kilogauss at 150C. Since the output voltage of a ferroresonant transformer depends on the Bsat value of the core material under the output windings, a rise in core operating temperature results in an undesirable decrease in the output 5~

voltage. If for example, the output voltage is an ultor high voltage, the ultor voltage developed immediately after the television receiver is turned on, while the ferroresonant transformer core is at ambient temperature, is greater than the ultor voltage developed during subsequent steady-state temperature operation after the core has heated to its normal above-ambient operating temperature.
Heat sinking of the core to reduce temperature rise is relatively difficult in a high frequency television receiver ferroresonant transformer. The output windings of the ferroresonant transformer, including the high voltage winding which has a relatively large number of turns, are wound around the saturating core portion of the transformer and tightly coupled magnetically one to another. The multiple output windings and the large number of high voltage winding turns restrict access to the core for heat sinking purposes.
In accordance with a preferred embodiment of the invention, a self-regulated power supply comprises a transformer including first and second windings. The first winding has terminals for coupling to a source of alternating input voltage. The second winding has terminals for coupling to a load.
A saturable reactor includes a magnetizeable core and at least one reactor winding wound on the core. The one reactor winding and the second winding of the transformer are conductively coupled to develop, when energizing, an alternating polarity voltage across the reactor winding.
30 The second winding of the transformer is magnetically isolated from the saturable reactor so that magnetic flux in the reactor core does not link with the second winding.

By magnetically saturating the reactor core, the voltages across the conductively coupled saturable reactor winding and transformer secondary winding are regulated.
A third winding of the transformer, such as the high voltage winding, is responsive to the regulated voltage developed 40 across the transformer secondary winding for developing ~,~t~7 1~

across the third winding a regulated alternating polarity output voltage. A load clrcuit such as the ultor circuit is coupled to the transformer third winding and is energized by the regulated output voltage.
An advantage of the above-recited arrangement is that the saturating core element which provides the voltage regulation is not a part of -the transformer core around which are wound the output secondary windings, which provide the television receiver regulated supply voltages. Thus, the high voltage winding is wound around the transformer core rather than around the saturable reactor core, providing easier access to the saturating core portion for heat sinking purposes.
Furthermore, the transformer core, under which the secondary output windings are wound, may be operated substantially in the unsaturated region of the B-H loop characteristic of the transformer core material. The output voltages across the transformer secondary windings are nonetheless regulated because the windings can be tightly magnetically coupled with the regulated output winding that is conductively coupled to the saturable reactor winding.
In the Drawing:
FIGURE 1 illustrates a ferroresonant television power supply embodying the invention; and FIGURES 2 and 3 illustrate waveforms associated with the operation of the circuit of FIGURE l.
In FIGURE 1, a ferroresonant television power supply 10 comprises a transformer 22 and a ferroresonant saturable reactor load circuit 20. A primary winding 22a of transformer 22 is coupled toa source 11 of unregulated alternating input voltage Vin comprising an inverter 21 and a DC input terminal 23 coupled to a center tap of primary 35 winding 22a. An unregulated DC voltage Va is applied to terminal 23. Inverter 21 is operated at a high frequency of, for example, the 15.75 KHz horizontal deflectionfrequency.
Inverter 21 develops the alternating input voltage Vin as a horizontal rate square-wave voltage across primary winding 22a.
When the voltage Vin is applied to primary winding ,.

l5'7 22a, horizontal rate alternating polarity output voltages are developed across secondary output windings 22b-22d and a high voltage secondary winding 22e. End leads 49 and 50 of output winding 22b are connected, respectively, to diodes 29 and 30, which act as a full wave rectifier; end leads 48 and 51 of output winding 22c are coupled, respectively, to diodes 27 and 28, which act as a full wave rectifier;
and end leads 47 and 52 of output winding 22d are coupled, respectively, to diodes 25 and 26, which act as a full wave rectifier. A common center tap lead 53 is coupled to ground.
The alternating polarity output voltage developed across winding 22b is full-wave rectified by diodes 29 and 30, and filtered by a capacitor 34 to develop a DC supply 15 voltage at a terminal 31, of illustratively +25 volts, to energize such television receiver circuits as the vertical deflection circuit and the audio circuit. The alternating polarity output voltage developed across winding 22d is full-wave rectified by diodes 25 and 26 and filtered by a capacitor 36 to develop a DC supply voltage at a terminal 33, of illustratively -~210 volts, to power such circuits as the picture tube driver.
The alternating polarity output voltage developed across winding 22c is full-wave rec-tified by diodes 27 and 28 and filtered by a capacitor 35 to develop at a -terminal 32 a B+ scan supply voltage for a horizontal deflection winding 41. To generate ho;-izontal scanning or deflection current in horizontal deflection winding 41, a horizontal deflection generator 40 is coupled to terminal 32 through an input choke 39. Horizontal deflection generator 40 is energized by the B+ scan supply voltage and comprises a horizontal oscillator and driver 43, a horizontal output transistor 44, a damper diode 45, a horizontal re-trace capacitor 46 and an S-shaping or trace capacitor 42 coupled in series with horizontal deflection winding 41 across horizontal output transistor 44.
The alternating polarity output voltage developed across high voltage seconr1ary winding 22e is coupled to a high voltage circuit 24 to develop a DC ultor high voltage or accelerating potential at a terminal U for the television ~ ~t~7~
1 ~5- RCA 75752 receiver picture tube, not illustrated. High voltage circuit 24 may comprise a conventional voltage multipli.er circuit of the Cockroft-Walton type, or may comprise a 5 half-wave rectifier arrangement with a plurality of diodes i.ntegrally molcled as a single unit with a plurality of winding sections, not individually illustrated, of high voltage s.econdary wi.nding 22e~
Secondary output windings 22b-22d and high voltage 10 secondary winding 22e are closely or tightly coupled magnetically one to another. To achleve the tigh~ coupling, the windinqs may be wound concentrically around a common portion of -the magnetizable core 122 of transformer 22.
Because of the tight magnetic coupling among the windings, 15 the alternating polari.ty output voltages developed across the seconda:r~,~ outpu-t windings are all of common waveshape, wiLh :little departure beincl introduced by the relatively small leakage inductances existing between the output windings.
To regulate the secondary output winding voltages against variations in the amplitude of the input voltage Vin and against loading changes by the load circuits coupled to terminals 31-33 and beam current loading changes on ultor terminal U, the ferroresonant saturable reactor load circuit 25 20 is coupled across one of the tightly or closely coupled secondary output windings of transformer 22. In FIGURE 1, the saturable reactor circuit 20 i5 illustratively coupled across secondary output winding 22d.
Ferroresonant saturable reactor load circuit 20 30 comprises a reactor coil or winding 37 wound around at least a portion of a saturating, magnetizable core 137 and comprises a resonating capacitor 38 coupled across reactor winding 37. Saturable reactor core 137 may be of a conventional toroidal or two-window rectangular core 35 design.
In a ferroresonant circuit such as the ferro-resonant saturable reactor load circuit 20 of FIGURE 1, the voltage Vout across the saturating coil 37 is regulated.
By coupling ferroresonant saturable reactor circuit 20 40 across the secondary output winding 22d of transformer 22, ~ 7~7 circuit 20 acts as a regulating load circuit coupled to winding 22d to main-tain the voltage across winding 22d at the regulated voltage Vout. With the voltage across 5 secondary winding 22d regulated by the ferroresonant load circuit 20, the output voltages across all the other secondary windings which are tightly coupled with winding 22d are also regulated. Thus, the output voltages across windings 22b and 22c and thehig}l voltaqe ou-tput t~linding 22e are regulated hy the regulating action on the voltage Vout of ferroresonant circuit 20.
Transformer 22 has substantial leakage inductance between primary winding 22a and each of the tightly coupled regulated secondary windings 22b-22e. The loose coupling of the primary winding with the secondary output windings enables the output voltage to be maintained substantially constant by ferroresonant circuit 20 even though the applied voltage across primary winding 22a may change with variations in the alternating input voltage Vin. Leakage inductance between primary winding 22a and each of the secondary windings 22b-22e may be designed into transformer 22 by constructing the magnetizeable core 122 of the transformer as a closed loop core of rectangular shape.
Primary winding 22 may be wound on one leg of core 122 and the secondary windings 22b-22e may be concentrically wound on an opposing leg.
When considering the equivalent electrical circuit of transformer 22, the load circuits coupled to terminals 31-33 and to ultor terminal U are reflected to the primary winding as load impedances in parallel with the reflection of the ferroresonant load circuit 20. Because of the loose magnetic coupling between the primary winding 22a and secondary windings 22b-22e, the reflected ferroresonant load circuit and the other parallel loads see an equivalent impedance in series with the source 11 of alternating input voltage Vin. This equivalent impedance produced by the loose magnetic coupling of transformer 22 absorbs the variations in input voltage while enabling the ferroresonant load circuit and output winding voltage amplitude variations to be substantially reduced in comparison to the voltage s~

amplitude variations of the primary winding.
E'IGURE 2a illustrates the square-wave a~ternating polarity input voltage Vin developed by source 11 across 5 primary winding 22a Gf transformer 22. Illustrated in Figure 2b is the regulated voltage Vout developed across ferroresonant saturable reactor load circuit 20 and secondary output winding 22d of -transformer 22. The re~ulat~d vo]tage Vou-t is an alternating polarity voltage t-he Scllll~ fr(?q~-!n~y ~1!; the input vol.tage Vin with generally flattcned portiolls 1~ alternating in polari.ty and connected 15 by generally sinusoidal portions 15.
Within the flattened portion intervals of the regulated output voltage Vout, such as be-tween times to-t of FIGURE 2b, the saturable reactor magnetizable core portion associated with coil 37 is being operated in the 20 magnetically unsaturated region of the core material B-H
loop characteristic. Saturable reactor coil or winding 37 exhibits a relatively large inductance during the flattened portion or unsaturated intervals. Relatively little current isr flows in the saturable reactor winding 37 as illustrated 25 in the solid-line waveform isr of FI~URE 2b between times to ~ tl .
With saturable reactor winding 37 exhibiting a relatively high impedance during the flattened portions or magnetically unsaturated intervals of the output voltage 30 waveform Vout, the resonating capacitor 38 is discharged very little i.nto the saturable reactor coil, and the capacitor maintains a relatively constant output voltage Vout applied across the coil terminals, as illustrated by the relatively small capacitor current ic, the dashed-line 35 waveform of FIGURE 2b, between times to-tl.
The output voltage Vout when applied by capacitor 38 across reactor winding 37 produces a flux buildup in the core 137 until substantial magnetic saturation of the core occurs near time tl. When core 137 40 magnetically saturates near time tl, the inductance of ..
,, 7~7~S'7 reactor coil 37 decreases substan-tially. The inductance of coil 37 may be,illustratively, 20 to 60 times less than the unsaturated inductance of the coil.
After core 137 becomes magnetically saturated, capacitor 38 and reactor coil 37 undergo a half cycle of resonant current oscillation, as indicated in FIGURE 2b by the current pulse 12 of the coil current isr and as indicated by the current pulse in the capacitor 10 current ic between times tl-t4. The resonant or circulating current in sa-turable reactor coil 37 and in capacitor 38 reaches maximum magnitude at time t3. The output voltage Vout reverses polarity, also at this time.
Near time -t4, resonant current pulse 12 has 15 decreased sufficiently to enable core 137 to come out of saturation, enabling the reactor coil 37 to reexhibit a high impedance. The voltage across capacitor 38, that is, the regulated output voltage Vout, stops its rapid change and assumes the opposite polarity 0 flattened portion values. During the opposite polarity flattened portion interval t4--t5, the core 137 is again operated in the magnetically unsaturated region of its B-H loop characteristic. The flux in core 137 reverses direction during this interval and builds up, 25 substantially, -to its saturation flux magnitude near time t5 when the core again magnetically saturates. The current in the reactor winding 37 then undergoes another half cycle of oscillation between times t5-t6.
Ferroresonant saturable reactor load circuit 20 30 functions as a magnetic voltage regulator to maintain a relatively constant amplitude output voltage Vout under varying input voltage conditions,and under varying loading conditions on the various secondary output windings such as under varying beam current loading of ultor terminal U.
35 With a sufficiently large value for capacitor 38, the ~C component of the flattened portions of the output vol-tage Vout is relatively small. The area under a flattened portion of the voltage waveform Vout equal~ the time integration of the output voltage Vout over the 40 flattened portion interval, or equivalently represents the Lt7~7:~5~7 maximum chanye in flux linkage of reactor coil 37.
The maximum flux linkage of coil 37 is proportional to the satura-tion flux density ssat of -the 5 magnetizable material of reactor core 137. Since the maximum flux linkage of reactor coil 37 is substantially a constant amount independent of input voltage variations, the area under the flattened portion of the output voltage Vout is also a constant independent of input voltage 10 variations~ Thus, the amplitude of the output voltage Vout will be regulated and of substan-tially unchanged value provided that the duration of the flattened portion of output voltage Vout during which the reactor core 137 is unsaturated remains relatively fixed.
The period of the alternating polarity output voltage Vout is that of the input voltage Vin and is of a fixed duration. Also the duration, within -this period, of the magnetically saturated intervals tl-t4 and t5-t6 is fixed by the value of the inductance of coil 37 near or at 20 saturation and by -the value of capacitor 38. The duration of the unsaturated portions of the output voltage Vout is therefore also fixed, thereby enahling the output voltage to assume a relatively constant amplitude.
With the secondary output winding 22d of transfoxmer 22 coupled across the ferroresonant saturable reactor load circuit 20, the voltage across output winding 22d is constrained to assume the regulated output voltage Vout even -though the input voltage Vin may vary in amplitude.
30 All the other secondary output windings 22~, 22c and high voltage winding 22e are similarly constrained to assume regulated voltages. Varying the input voltage and loading of the output windings varies the shift in phase of the alternating output voltage Vout relative to the phase of 35 the alternating input voltage Vin while maintaining the amplitude of the output voltage Vout relatively unchanged.
As illustrated in FIGURES 2a and 2b, at an operating condition of nominal input voltage and of average loading on output windings 22b-22e, e.g., at 40 approximately 1/2 milliampere beam current loading, the ~ '71~7 1 ~10- RCA 75752 output voltage Vout is phase delayed by an amount ~\t relative to the phase of the inpu-t voltage. T'ne phase delay ~t occurs because of the power dissipation in the load 5 circuits coupled to secondary output windings 22b-22e. The phase delay between Vin and Vout enables power to be transferred from source ll to the secondary output winding load during each cycle of the input or output voltage oscillation.
As illustrated in FIGURES 3a and 3b, when the input voltage Vin varies from a high-line input voltage level to a low-line input voltage level, the phase delay of the output voltage Vout increases from a delay of ~t to a delay of ~t2. The increase in phase delay at the lower input voltage level occurs because a greater phase delay is required at the lower input voltage level to transfer the same average power to the secondary winding loads. Although the Phase delay of the output voltage Vout has increased at the lower input voltage level, the amplitude of Vout and the half cycle average voltage ~as not significantly changed, thereby providing the required regulation against input voltage variations.
As illustrated in FIGURES 3c and 3d, when beam current loading of ultor terminal U increases from zero 25 to 1.7 milliamperes, the phase delay of the output voltage Vout increases from a phase delay of Qta to a delay of ~tb~ at, for example, the same, nominal input voltage level. The increase in phase delay occurs because a greater phase delay is required to transfer more average power at the greater secondary winding loading condition. Although -the phase delay of the outpu-t voltage Vout has increased, the amplitude of Vout in FIGURE 3d and the half cycle average voltage has not significantly changed, thereby providing the required regulation against loading variations.
A feature of the invention is to provide regulated output voltages across transformer secondary windings without requiring the core portion of the transformer associated with the secondary windings to magnetically saturate. Thus, the power transformer that is coupled to the AC voltage , 1 -11- ~CA 75752 source, such as transformer 22 of FIGURE 1, does not have the design con~straints imPosed upon it that a ferroresonant transformer has. In contrast to the use of a ferroresonant 5 transformer, the portion of the transformer magnetizable core 122 associated with or under the transformer secondary output windings 22b-22d may be operated in the linear region of the core material B-H
loop characteristic. The core remains substantially 10 unsaturated magnetically during the entire alternating polarity output voltage cycle.
Several advantages accrue by using the inventive arrangement of FIGURE 1 wherein a power transformer provides regulated output voltages across secondary output windings 15 but the core of the transformer, nonetheless, is operated--in the linear region of its B-H loop characteristic,and wherein-~ -the regulation is achieved by a separate ferroresonant saturable reactor circuit coupled as a regulating load across one of the power transformer output windings. For 20 example, in a ferroresonant transformer arrangement, unlike in the arrangement of FIGURE 1, a relatively high circulating or resonant current flows in one of the ferroresonant transformer output windings. To reduce I R
losses in that winding, a relatively thick or large 25 cross-section conductor wire is used. Such a thlc~
conductor wire interferes with tight coupling, so that leakage inductance is higher than desired.

In contrast, no large circulating or resonant current flows in any of the output secondary windings of power transformer 22 of FIGURE 1. As illustrated in 35 FIGURE 2c, for example, the current iw flowing out of output winding 22d to ferroresonan~ load circuit 20 is of relatively small amplitude with a peak magnitude, illustratively,ten or more times smaller than the Peak magnitude of the resonant current pulse 12 flowing in 4~ reactor coil 37. Only enough current iw on average need '7:~LS~7 flow out of transformer 22d to replenish the losses incurred during each cycle of the alternatlng polarity regulated output vol-tage Vout. Losses include hysteresis 5 and eddy current heating of the reactor magnetizable core 137, I R losses in the reaetor coil 37. Losses also include energy losses susta;ned by capacitor 38 during each cycle of the output voltage Vout that occur due to load current Elowing out of terminal 33 and due to load 10 current flowing to the load circuits coupled to terminals 31 and 32 and ultor terminal U as reflected into output winding 22d.
Another advantage of the arrangement of FIGURE 1 is the greater design flexibili-ty provided in selecting 15 the parameters of the ferroresonant load circuit 20 of the power suppl~ sys-tem 10 without requiring redesign of the power transformer portion 22 of -the system. Beeause seeondary output winding 22d of transformer 22 is magnetieally isolated from saturable reaetor eoil 37 and 20 magnetizable eore 137, that is, beeause the magnetic flux flowing in reac-tor core 137 does not link -the -transformer output winding 22d, design changes in the magnetizable core 137 and in the values of the resonant or eireulating eurrent provided by eapacitor 38 do not require any 25 substantial design changes to transformer 22, provided the ehanges in ferroresonantload eireuit 20 do not signifieantly degrade the regulation of output voltage Vout.
The amplitude of the output voltage Vout produeed by ferroresonant load eireuit 20 is related -to the 30 saturation flux density Bsat eharaeteristie of the magnetizable material of reaetor eore 137. To reduee eddy eurrent losses in eore 137 when operating ata relatively high frequency of 16 KHz or more, a eore material with a relatively high resistanee -to eddy eurrent flow is 35 seleeted. Commercially available core materials that may be used for saturable reactor core 137 are, for example, manganese-zine ferrites, niekel-zine ferrites, or lithium ferrites. Manufaeturing proeess toleranee in the produetion of the ferrite core material may result in relatively large 40 toleranees in the value of the material Bsat.

7~7~57 To take into account the ssat tolerance from core unit to core unit, the number of conductor turns of reactor coil 37 wound around core 137 may be varied for 5 each core unit in order to maintain the output voltage Vout unchanged from unit -to unit. Since regulated output voltages for most of the television receiver circui-ts are obtained across output windings from a separate transformer, the tolerances in Bsat of core 137 and the variations in 10 conductor turn number for coil 37 to compensate there-for do not require corresponding changes in the number of turns or other parameters of transformer 22.
The value of Bsat of the magnetizable material of reactor core 137 is a function of the operating temperature 15 of the core, with the value of Bsat decreasing as the operating temperature increases, Core 137 heats up after initial television receiver turn~on because of hys-teresis and eddy current losses sustained during opera-tion,and because of the heating due to I R losses, of -the 20 conductor wire of coil 37 wound around reactor core 137.
Prior to energization of power supply 10, the temperature of saturable reactor core 137 is the ambient temperature.
After energizatlon of the power supply, the core 137 heats to some steady-state temperature value above ambient.
25 During the time interval when the core is heating, the Bsat of the core decreases.
Thus, the output voltage Vout of the ferroresonant regulating load circuit 20 decreases from its initial value at turn-on of the television receiver to a 30 lower steady-state value when the final operating temperature of core 137 is reached.
To minimize the temperature change from start-up -to steady-state temperature operation, the saturable reactor coil 37 and core 137 may be heat sinked in a 35 conventional manner to a cooling plate or to the television receiver metal chassis. Heat sinking of the saturable reactor core 137 of the inventive arrangement of FIGUR~ 1, where only one or a small number of coils are wound around the reactor core 137, is a relatively less difficult 4~ procedure than heat sinking of the saturating core portion ~ .f -l4-- ~('A 7rj7r of a ferroresona~ tranc;forrller ~ihich ~rovides multi~le out~ut voltages across multiple outpu-t windings wound around the saturating core portion of the ferroresonant transformer.
5 Furthermore, it is even more difficult to heat sink a ferroresonant transformer having a high voltage winding because the large number of turns wound around the saturatinc~ core portion of the -transformer blocks access to tlle core ~ortion.
In FIGURE 1, heat sinking of the core 122 of power transformer 22 is not required since the power transformer core material is operated in the linear region of iks B-~l loop characteristic and thus incurs relatively little core loss and little operatiny temperature rise.
15 Furthermore, no circulating or resonant current flows in any of the output windings of transformer 22. I R losses in the transformer output windings and heating of the transformer core 122 therefrom are relatively insignificant.
In an illustrative embodiment of power transformer 20 22, th~ pr:imary windin() inductance, Ll" as measllrocl fronl the center ta~ termina1 to an end terminal, is 2.03 millihc~rics;
the secondary inductance LS of secondarv winding 22d is 10.3 millihenries; and the mutual inductance, ~1, between the above two described windings is 3.35 millihenries. The 25 core material may be a manganese-zinc ferrite,and the transformer core geometry may be of any suitable arrangement that will provide the above inductance values while maintaining the core magnetically unsa-turated.
In an illustrative embodiment of ferroresonant 30 load circuit 20, the value of capacitor 38 may be 0.033 microfarad; the core material saturation flux density, cross-sectional area and number of turns may then be selected so as to produce a Vout waveform similar to that of FIGURE 2b, during the unsaturated intervals 35 to-tl and t4-t5, with the value of unsaturated inductance of coil 37 being relatively large, on the order of one henry. The number of turns, the core geometry, such as mean magne-tic path length and cross-sectional area, and the core ma-terial B-H characteristic are such that when substantial macJnetic ~; 40 saturation occurs, near times tl and tS of Fl(,URE 2~, the 7'73LS~
1 -15- RCA 75,752 inductance of coil 37 decreases substantially to around 500 microhenries ~r even less at peak currents. A suitable core material may be a ferrite such as a lithium-bismuth ferrite which has the added advantage of a rela-tively small change in Bsat with core operating temperature change ~7hen compared to many other ferrites. The core may be constructed as a -toroid or as a double E-core.

.

i 40

Claims (12)

-16- RCA 75,752 WHAT IS CLAIMED IS:

1. A television system with a ferroresonant load regulated high voltage power supply, comprising:
a source of unregulated alternating input voltage;
a transformer having primary, secondary and high voltage windings, said primary winding being coupled to said source for developing alternating polarity voltages across said secondary and high voltage windings that tend to undesirably vary with variations of said unregulated voltage;
a high voltage circuit coupled to said high voltage winding for developing an ultor voltage from the high voltage winding alternating polarity voltage; and a ferroresonant saturable reactor core and a load coil wound on said core and conductively coupled to and magnetically isolated from said transformer secondary winding, said ferroresonant saturable reactor load coil being responsive to and providing regulation of the transformer secondary winding alternating polarity voltage for developing a regulated alternating polarity voltage across said high voltage winding.

2. A television system according to Claim l wherein said high voltage winding is closely coupled magnetically with said transformer secondary winding and including a fourth transformer winding closely coupled magnetically with said transformer secondary winding and a deflection generator energized by the voltage developed across said transformer fourth winding for generating deflection current.

3. A television system with a ferroresonant load regulated deflection generator power supply, comprising:
a deflection generator including a deflection winding;

RCA 75,752

CLAIM 3 CONTINUED
a source of unregulated alternating input voltage;
a deflection generator including a deflection winding;
a transformer having primary and secondary windings, said primary winding being coupled to said source for developing an alternating polarity voltage across said secondary winding that tends to undesirably vary with variations of said unregulated voltage;
means responsive to said secondary winding alternating polarity voltage for developing a B+ scan supply voltage therefrom;
means for applying said B+ scan supply voltage to said deflection generator to develop scanning current in said deflection winding; and a ferroresonant saturable core and load coil wound thereon and conductively coupled to and magnetically isolated from said transformer secondary winding, said ferroresonant load coil being responsive to and providing regulation of the transformer secondary winding alternating polarity voltage for developing a regulated B+
scan supply voltage.

4. A television system according to Claim 3 including a high voltage winding closely coupled magnetically with said transformer secondary winding voltage and a high voltage circuit coupled to said high voltage winding for developing a picture tube ultor voltage.

5. A television system according to Claims 1, 3 or 4 including a capacitance coupled to said load coil in such a manner as to generate a circulating current that magnetically saturates the core portion associated with said coil during each cycle of said load coil alternating voltage to regulate the voltage developed across said secondary winding without generating said circulating current in the secondary winding.

-18- RCA 75,752

6. A television system according to Claim 1, 3 or 4 wherein the transformer core portion associated with said transformer secondary winding remains substantially unsaturated magnetically during the entire cycle of the transformer secondary winding alternating voltage.

7. A television system according to Claim 1, 3 or 4 wherein said transformer primary and secondary windings are loosely coupled magnetically to enable the secondary winding voltage to be substantially unchanged in amplitude with primary winding voltage variations.

8. A television receiver including a ferroresonant regulated power supply, comprising:
a source of alternating input voltage;
a transformer including first and second windings, said first winding being coupled to said source for developing an alternating polarity voltage across said second winding, said alternating polarity voltage having a tendency to undesirably vary with variations of said alternating input voltage;
a saturable reactor including a magnetizable core and a reactor winding wound on said core, said reactor winding and said transformer second winding being conductively coupled to develop an alternating polarity voltage across said reactor winding, said transformer second winding being magnetically isolated from said saturable reactor such that the magnetic flux flowing in said reactor core does not link said transformer second winding;
a capacitance coupled to a winding of said saturable reactor for developing a circulating current that aids in magnetically saturating a portion of said reactor core associated with the reactor winding that is conductively coupled to the transformer second winding for reducing by means of ferroresonant regulation the voltage variations across the conductively coupled saturable reactor winding with variations in input voltage in order -19- RCA 75, 752

CLAIM 8 CONTINUED
to regulate the voltage across said transformer second winding against the above tendency to vary with variations of input voltage;
a high voltage winding of said transformer responsive to the regulated voltage developed across said transformer second winding for stepping up the voltage developed across said second winding;
an ultor terminal;
a high voltage rectifier arrangement coupled to said transformer high voltage winding and to said ultor terminal for developing a regulated DC ultor voltage from the stepped up voltage;
said third winding of said transformer responsive to the regulated voltage developed across said transformer second winding for developing a regulated output voltage across said third winding; and a load circuit coupled to said transformer third winding and energized by said regulated output voltage.

9. A television receiver including a regulated power supply according to Claim 8 wherein said transformer includes a fourth winding responsive to the regulated voltage developed across said transformer second winding for developing a regulated voltage across said fourth winding; and wherein said television receiver includes a deflection winding, means responsive to said transformer fourth winding regulated voltage for developing a B+ scan supply voltage, and a deflection generator responsive to said B+ scan supply voltage for generating scanning current in said deflection winding.

10. A television receiver including a regulated power supply according to Claim 8 or 9 wherein said second winding is wound on a magnetizable core of said transformer, the portion of said transformer magnetizable core associated with said second winding remaining substantially unsaturated magnetically during the entire -20- RCA 75,752

CLAIM 10 CONTINUED
cycle of said transformer second winding alternating polarity voltage.

11. A television receiver including a regulated power supply according to Claim 8 or 9 wherein said transformer is designed with loose magnetic coupling between said first and second windings so as to create an equivalent impedance in series with said source of input voltage for absorbing variations in input voltage while enabling the voltage across said second winding to remain substantially constant with said variations.

12. A color television receiver including a regulated power supply according to Claim 8 wherein said second and high voltage windings of said transformer are concentrically wound on the magnetizable core of the transformer, and wherein said capacitance is directly in-circuit with a winding of said saturable reactor for preventing the flow of circulating current into the second winding of said transformer.