Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
  • H01F38/42—Flyback transformers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/02—Bases, casings, or covers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F5/00—Coils
  • H01F5/02—Coils wound on non-magnetic supports, e.g. formers
  • H01F2005/022—Coils wound on non-magnetic supports, e.g. formers wound on formers with several winding chambers separated by flanges, e.g. for high voltage applications

Definitions

• the invention is based on a high-voltage transformer according to the preamble of claim 1.
• a transformer is known from DE-OS 35 14 308.
• Such transformers generate a high voltage for television receivers in the order of 25 kV.
• the object of the invention is to reduce the power loss occurring at the transformer in such a high-voltage transformer. This object is achieved by the invention specified in claim 1. Advantageous developments of the invention are specified in the subclaims.
• the invention is initially based on an analysis of the total loss types occurring in such a transformer.
• a first type of loss consists in the ferrite losses due to magnetization of the core in accordance with the area formed by the hysteresis curve. Such losses can only be reduced by ferrite material of increased quality.
• a second type of loss consists of copper losses due to the ohmic resistance of the wire and the skin effect.
• a third type of loss consists in the losses in the high-voltage rectifier diodes, namely through the forward voltage and the forward current, the reverse voltage and the reverse current and the switch losses when switching from the blocked to the conductive state and vice versa.
• a fourth type of loss consists in the dielectric losses due to displacement es currents in the dielectric generally formed by a potting resin.
• the invention is based on the following consideration.
• the dielectric losses occur in particular in the area between the primary winding and the secondary winding or high-voltage winding, because the greatest voltage differences exist here. If it is thus possible to make this area largely electrically field-free, the dielectric losses can be considerably reduced. In the invention, this is achieved only by a particularly advantageous division of the pulse voltages on the primary winding and on the secondary winding, in such a way that in the area mentioned on the primary winding and on the secondary winding, the pulses have approximately the same amplitude and polarity.
• the difference in the impulse voltages on the two windings practically disappears, so that in the desired manner an electrically field-free space is achieved and losses due to dielectric displacement currents are avoided as far as possible.
• a major advantage is that the field-free space is not achieved by additional means, but only by a clever arrangement of the parts that are required anyway.
• the harmonic content of the generated voltages is also reduced by reducing the dielectric displacement currents in the dielectric surrounding the windings. This leads to fewer natural resonances that are otherwise triggered by displacement currents. This reduction in the harmonics causes an improvement in the internal resistance and also a reduction in the acoustic noises occurring at the transformer. Overall, the material surrounding the windings, preferably a cast resin, is also less stressed.
• FIG. 1 shows the structural design of a high-voltage transformer according to the invention and
• FIG. 2 shows an equivalent circuit diagram for the transformer according to FIG. 1.
• the bobbin 7 is supported on the core 1, which carries the primary winding 3.
• the primary winding 3 consists of six layers.
• the winding end from the lower layer is connected to terminal b with the operating voltage + UB.
• the end of the winding from the upper layer is connected to terminal d and to switching transistor 13, which is controlled at terminal c with a line-frequency switching voltage Z.
• the pulse voltage at terminal b is zero.
• the pulse voltage at terminal d has the full value of the return voltage of +1200 volts. The pulse voltage thus increases continuously from the value zero at terminal b to the maximum value at terminal d from winding to winding.
• the pulse voltage decreases by about 16% over the axial length of the upper layer of winding 3 and the pulse voltage at the right end of the upper layer is +1000 volts.
• the pulse voltage is therefore largely constant in the upper position of the winding 3 over the axial length of the coil former 7 and has an average value of 1100 volts.
• the chamber coil former 2 Arranged above the coil former 7 with the primary winding 3 is the chamber coil former 2, which has a total of 16 chambers Ka to Kp formed by walls 8, which are filled with partial windings 4a to 4p of the secondary winding or high-voltage winding 4.
• the winding end from the upper layer of the first partial winding 4a is connected to earth.
• the winding end at the bottom of a chamber K is connected to the anode ner high-voltage rectifier diode 6, the cathode of which is connected in each case to the winding end from the upper end of the next partial winding 4.
• the end of the winding from the bottom of the last partial winding 4p in the bracket Kp forms the high-voltage terminal a.
• the winding process for the entire secondary winding 4 begins at the bottom of the chamber Kp. Since there is a diode 6 between each two chambers, a total of 15 diodes 6 are provided for a total of 16 chambers K. A high voltage UH of 32 kV develops at terminal a. With these assumed values, there is a pulse of +1100 volts at the bottom of a chamber K, which is the same size in all chambers. At the upper end of winding 4 there is a pulse of -1300 volts.
• the high-voltage winding 4 also generates pulses with the constant amplitude of +1200 volts in the area assigned to the winding 3, that is to say in the area of the lower ends of the chambers.
• the pulses on the winding 3 and on the winding 4 are also the same. There is therefore practically no voltage difference between the pulses on the winding 3 and the pulses on the winding 4, so that the electrically field-free space indicated by the dash-dotted line F results.
• the upper end of the first winding 4a is grounded and therefore does not carry any pulse voltage, while on the other hand the lower end of the last winding 4p, which is grounded via the capacitance of the picture tube, likewise does not carry any pulse voltage.
• the tension ratios of these two windings are therefore different from that of the other windings 4b to 4o.
• the primary winding 3 is preferably wound from Lit ⁇ ze in order to keep the losses due to the skin effect low.
• FIG. 2 shows the equivalent circuit diagram belonging to FIG. 1.
• the capacitor 14, which is essentially formed by the anode coating of the picture tube 15, is connected to the terminal a carrying the high voltage UH. 1 corresponds to the first diode between the bottom of the chamber Ka and the winding end at the upper end of the chamber Kb.
• the last diode 6p corresponds to the diode between the lower end of the winding of the chamber Ko and the upper winding end of the last chamber Kp.
• the primary winding 3 it is also possible to divide the primary winding 3 into a plurality of partial windings which are axially adjacent to one another on the core 1 and are connected in parallel between the terminals b and d.
• the amplitude at the upper layer of the primary winding 3 is different over the axial length. This can be taken into account in that the chambers Ka to Kp are filled accordingly differently, so that the pulses of the partial windings 4a to 4p each have different amplitudes at the bottom of the chamber.
• the filling factor of the chambers K with the partial windings 4 would then decrease from the left to the right end of the coil formers 7.2 as the amplitude of the pulses at the upper position of the winding 3 also decreases, ie in FIG. 1 from +1200 volts to +1000 volts.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Coils Or Transformers For Communication (AREA)
• Details Of Television Scanning (AREA)
• Television Receiver Circuits (AREA)
• Dc-Dc Converters (AREA)
• Coils Of Transformers For General Uses (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6419986

Family Applications (1)

Country Status (16)

Cited By (4)

Families Citing this family (3)

Citations (3)

Family Cites Families (4)

• 1990
  • 1990-12-10 DE DE4039373A patent/DE4039373A1/de not_active Withdrawn
• 1991
  • 1991-12-03 ES ES91920765T patent/ES2097823T3/es not_active Expired - Lifetime
  • 1991-12-03 EP EP91920765A patent/EP0561839B1/de not_active Expired - Lifetime
  • 1991-12-03 KR KR1019930701737A patent/KR100194191B1/ko not_active IP Right Cessation
  • 1991-12-03 WO PCT/EP1991/002285 patent/WO1992010906A1/de active IP Right Grant
  • 1991-12-03 HU HU9301604A patent/HUT64660A/hu unknown
  • 1991-12-03 SG SG1996005830A patent/SG46549A1/en unknown
  • 1991-12-03 JP JP51869891A patent/JP3280965B2/ja not_active Expired - Fee Related
  • 1991-12-03 CA CA002098100A patent/CA2098100A1/en not_active Abandoned
  • 1991-12-03 DE DE59108593T patent/DE59108593D1/de not_active Expired - Fee Related
  • 1991-12-09 MX MX9102455A patent/MX9102455A/es not_active IP Right Cessation
  • 1991-12-09 MY MYPI91002277A patent/MY107209A/en unknown
  • 1991-12-09 TR TR91/1196A patent/TR25836A/xx unknown
  • 1991-12-10 PT PT99742A patent/PT99742B/pt not_active IP Right Cessation
  • 1991-12-10 ZA ZA919724A patent/ZA919724B/xx unknown
• 1993
  • 1993-06-09 FI FI932627A patent/FI932627A/fi not_active Application Discontinuation
• 1997
  • 1997-12-08 HK HK97102361A patent/HK1000744A1/xx not_active IP Right Cessation

Patent Citations (3)

Also Published As

Similar Documents

Legal Events