CA1249023A - Apparatus for auxiliary power supply from a generator field - Google Patents
Apparatus for auxiliary power supply from a generator fieldInfo
- Publication number
- CA1249023A CA1249023A CA000469644A CA469644A CA1249023A CA 1249023 A CA1249023 A CA 1249023A CA 000469644 A CA000469644 A CA 000469644A CA 469644 A CA469644 A CA 469644A CA 1249023 A CA1249023 A CA 1249023A
- Authority
- CA
- Canada
- Prior art keywords
- rotor
- winding
- voltage
- power
- power supply
- Prior art date
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
Abstract
APPARATUS FOR AUXILIARY POWER SUPPLY
FROM A GENERATOR FIELD
ABSTRACT OF THE DISCLOSURE
A power supply for mounting on the rotor of a large generator for providing power to auxiliary equipment also mounted on the rotor is described. The generator must have an external field supply which uses phase controlled SCRs as the switching of the SCRs causes a high frequency ac voltage to be superimposed on the dc supplied to the rotor field winding. The power supply has a high frequency transformer with two windings. One of the windings is connected in series with a capacitor across the field winding. The other transformer winding is connected to a bridge rectifier and the rectifier is connected to a filter and a voltage limiter. The supply is preferably used to charge a battery mounted on the rotor to provide electrical power to auxiliary equipment on the rotor, for example telemetry equipment.
FROM A GENERATOR FIELD
ABSTRACT OF THE DISCLOSURE
A power supply for mounting on the rotor of a large generator for providing power to auxiliary equipment also mounted on the rotor is described. The generator must have an external field supply which uses phase controlled SCRs as the switching of the SCRs causes a high frequency ac voltage to be superimposed on the dc supplied to the rotor field winding. The power supply has a high frequency transformer with two windings. One of the windings is connected in series with a capacitor across the field winding. The other transformer winding is connected to a bridge rectifier and the rectifier is connected to a filter and a voltage limiter. The supply is preferably used to charge a battery mounted on the rotor to provide electrical power to auxiliary equipment on the rotor, for example telemetry equipment.
Description
Case 2846 APPARATUS FOR AUXILIARY POWER SUPPLY FROM
A GE~ERATOR FIELD
BACKGROU~D OF THE INVE~TION
This invention relates to apparatus for providing auxiliary power from a generator field, and in particular it relates to apparatus for mounting on the rotor of a generator to provide a source of auxiliary power on the rotor.
It is often desirable to have auxiliary equipment mounted on the rotor of a generator, for example to monitor the temperature of conductors in the field winding or the insulation surrounding the conductors, or to monitor electromagnetic radiation ~ that might occur in the stator windings because of lS corona discharge, or to monitor other paramaters, and to transmit the data representing the monitored parameter from the rotor to an externally located receiver. For example, Canadian Application Serial No. 436,336, filed September 9, 1983 in the name of James S~ Mark and assigned to Canadian General Electric Company Limited describes a telemetry sy~tem using infra red radiation for transmittin~ data between the rotor of a generator and externally located equipment. Auxiliary equipment of this nature requires a supply of electrical power to operate. The amount of power required by such equipment is $
~ . .
~5~Q23 Case 2~46 relatively small, for example with a voltage up to perhaps 24 volts d~ and a current of perhaps up to two amperes and frequently less. This power can be provided to the rotor through slip rings from an external source, or it can be provided by a battery mounted on the rotor.
It is often difficult to provide extra slip rings on a generator for the purpose of providing auxiliary power to the rotor because there is usually little space available on the shaft of the rotor for mounting auxiliary equipment and it is expensive to provide space for this purpose. Additionally, extra slip rings provide another complication to the design. On the other hand, battery power is suitable, but the battery must be replaced or it must be recharged periodically. It is, of course, not feasible to shut down a large generator in order to replace a battery.
It will be apparent that there is, however, a large source of power available on the rotor. There must be direct current (dc) power to supply the generator field windings. As one example only, a typical 100 ~W generator might have a field supply rated at + 3~0 volts dc at perhaps 1000 to 1300 amperes. With all this power available on the rotor it should be possible to supply auxiliary equipment re~uîring perhaps a voltage up to 24 volts at perhaps one or two amperes. However it i5 not a simple matter to derive suitable power with a supply of a conveniently small size to mount on the rotor. It is not efficient to use dropping resistors across the field and then to tap off the required 9, 12 or 24 volts. Too much power would be wasted and there is another problem related to control of the field current.
A large power generator normally has a ~2~v ~3 Case 2846 current regulated field supply to control the generator output in accordance with a varying load.
The rate at which ~he generator output responds to load changes mus-t be fa~t and it ls therefore quite common to use an electronically regulated field supply. Such field supplies are normally phase controlled rectifiers which can quickly change the time at which conduction starts in a thyristor rectifier or silicon controlled rectifier (SCR). The delay time, or angle of retard, after the vol~age starts to go positive will vary the current conducted by the rectifier and hence the average output voltaye.
Another complication is that forcing voltages may be used to obtain rapid changes in field current. The field current of a large generator may be one or two thousand amperes and it will be fed in-to the field winding which may have an inductance of several henries. It is difficult to make rapid changes of field current under these conditions and i-t is common practice to "force" current changes up or down by voltage changes which go rapidly up and down in excess of normal changesO Forcing may be up to eight or ten times normal which means for a 300 volt dc supply the actual voltage could be up to 200Q volts dc or even 300Q volts dc. Thus the field supply must be able to pxovide a voltage of either polarity at any given time. It is common practice to use a phase controlled converter having two quadrant operation. A
description of such a phase controlled converter may be found, for example, in the text book "Thyristor Phase~Controlled Converters and Cycloconverters" by B.R. Pelly, Wiley-Interscience, 1971, Chapter 3.
It is therefore not practical to place dropping resistors across the field to try to obtain a supply of 24 volts for auxiliary equipment on the , :~
Case ~846 rotor. It is, in fact, difficult to obtain a unipolar supply of ~24 volts dc by any means from a field supply which may be of either polarity with a value of perhaps 3000 volts peak to peak negative to positive.
In a field current power supply using phase controlled SCRs, each time the SCRs are turned on or start to conduct at a time later than the time the voltage is available to cause conduction, there is a rapid change which generates high frequency components which appear to extend into the 50 Khz range. These high frequency components or disturbances in the unfiltered field supply are undesirable ox at least unnecessary insofar as the operation of the generator i5 concerned, by they can be used by the apparatus of the invention to provide a source of auxiliary power.
SUMMARY OF THE INVENTION
The present invention makes use of high frequency ac components present in the field supply to the rotor field windings. These high frequency ~O components are present when there i5 a current regulated field supply and the regulation is electronic regulation. The apparatus of this invention would not function if all the high frequency components were eliminated from the field supply, for example by extensive high frequency filtering.
However, it is an unnecessary expense to provide high frequency filtering for a generator field supply when such filtering has no practical value.
The apparatus of this invention has a high frequency transformer (sometimes ref~rred to as a pulse transformer) with two windings. The first winding is connected in series with a high voltage capacitance across the field supply on the rotor of a generator. The second winding is connected to a rectifier. The rectifier output is preferably filtered and has a current limiting device and a Case 2846 voltage control device. The limited and controlled output may be used to keep a battery fully charged to power auxiliary equipment.
It i5 another object of the invention to provide a source o~ auxiliary power on the rotor of a generator, where the source utili7es high ~requency ac components in the electrical supply to the generator field winding where the ac components are largely created by the switching in an electronically regulated field supply~
Accordingly there is provided a power supply for the rotor of a generator having a field winding on the rotor and a source of power for the field winding having high frequency ac components comprising a high frequency transformer having a first and a second winding, a capacitor for connection in series with said first winding across said field supply of saicl rotor, a rectifier connected to said second winding and rectifying ac voltages from said second winding, and ~ilter means connected to said rectifier to filter the rectified voltages from said rectifier and provide a source of power for auxiliary equipment on said rotor.
It is therefore an object of the invention to provide an improved auxiliary power supply for mounting on the rotor of a generator.
BRIEF DESCRIPTION OE' THE DRAWINGS
Figure 1 is a simplified schematic drawing showing the invention, and Figures 2 and 3 are graphs of voltaye plotted against time showing an example of a partial cycle of voltage in the converter providing the field supply and the input of the supply of the invention.
Case 2~46 DESCRIPTION OF TH~ PREF~:RRED EM~3ODIM:~NT
Referxlny to ~igure 1 there is shown a schematic drawing having conductors 10 and 11 on the rotor of a generator which conduct current to the rotor field windings (not shown). Across conductors 10 and 11 a capacitor 12 and a winding 14 of transformer 15 are connected in series. The capacitor 12 must have a high voltage rating sufficient to withstand the forcing voltages which may be applied to conductors 10 and 11 to force a desired field current through the field winding, and consequently it may in practice be several capacitors in series.
Transformer 15 is a high frequency transformer preferably capable of handling frequencies which extend to at least several kilohertz. ~le winding 16 of transformer 15 is connected to a bridge rectifier 17. The individual rectifiers used in the bridge rectifier 17 are high speed rectifiers, for example type A115 (G~neral Electric Company). The output of bridge rectifier 17 is on conductors 18 and 20 and capacitors 21 and 22 are connected across this output. Capacitor 21 is to pass high frequency transients and may be of the order of 0.33 ufd.
Capacitor 22 is a filter capacitor and may be of the order of 5500 ufd at 75 volts dc. A zener diode 23 and a capacitor 24 are connected across conductors 18 and 20. The zener diode 23 is selected to break down at a voltage which is very generally about twice the desired ou~put voltage of the power supply. More specifically, the zener diode 23 is selected to have a breakdown voltage which will protect the three terminal regulators used in the following circuitry and described subsequently. If the desired power supply voltage is 24 volts dc, the zener diode might have a breakdown voltage of the order of 51 volts. A
resistor 25 connects the junction of zener diode 23
A GE~ERATOR FIELD
BACKGROU~D OF THE INVE~TION
This invention relates to apparatus for providing auxiliary power from a generator field, and in particular it relates to apparatus for mounting on the rotor of a generator to provide a source of auxiliary power on the rotor.
It is often desirable to have auxiliary equipment mounted on the rotor of a generator, for example to monitor the temperature of conductors in the field winding or the insulation surrounding the conductors, or to monitor electromagnetic radiation ~ that might occur in the stator windings because of lS corona discharge, or to monitor other paramaters, and to transmit the data representing the monitored parameter from the rotor to an externally located receiver. For example, Canadian Application Serial No. 436,336, filed September 9, 1983 in the name of James S~ Mark and assigned to Canadian General Electric Company Limited describes a telemetry sy~tem using infra red radiation for transmittin~ data between the rotor of a generator and externally located equipment. Auxiliary equipment of this nature requires a supply of electrical power to operate. The amount of power required by such equipment is $
~ . .
~5~Q23 Case 2~46 relatively small, for example with a voltage up to perhaps 24 volts d~ and a current of perhaps up to two amperes and frequently less. This power can be provided to the rotor through slip rings from an external source, or it can be provided by a battery mounted on the rotor.
It is often difficult to provide extra slip rings on a generator for the purpose of providing auxiliary power to the rotor because there is usually little space available on the shaft of the rotor for mounting auxiliary equipment and it is expensive to provide space for this purpose. Additionally, extra slip rings provide another complication to the design. On the other hand, battery power is suitable, but the battery must be replaced or it must be recharged periodically. It is, of course, not feasible to shut down a large generator in order to replace a battery.
It will be apparent that there is, however, a large source of power available on the rotor. There must be direct current (dc) power to supply the generator field windings. As one example only, a typical 100 ~W generator might have a field supply rated at + 3~0 volts dc at perhaps 1000 to 1300 amperes. With all this power available on the rotor it should be possible to supply auxiliary equipment re~uîring perhaps a voltage up to 24 volts at perhaps one or two amperes. However it i5 not a simple matter to derive suitable power with a supply of a conveniently small size to mount on the rotor. It is not efficient to use dropping resistors across the field and then to tap off the required 9, 12 or 24 volts. Too much power would be wasted and there is another problem related to control of the field current.
A large power generator normally has a ~2~v ~3 Case 2846 current regulated field supply to control the generator output in accordance with a varying load.
The rate at which ~he generator output responds to load changes mus-t be fa~t and it ls therefore quite common to use an electronically regulated field supply. Such field supplies are normally phase controlled rectifiers which can quickly change the time at which conduction starts in a thyristor rectifier or silicon controlled rectifier (SCR). The delay time, or angle of retard, after the vol~age starts to go positive will vary the current conducted by the rectifier and hence the average output voltaye.
Another complication is that forcing voltages may be used to obtain rapid changes in field current. The field current of a large generator may be one or two thousand amperes and it will be fed in-to the field winding which may have an inductance of several henries. It is difficult to make rapid changes of field current under these conditions and i-t is common practice to "force" current changes up or down by voltage changes which go rapidly up and down in excess of normal changesO Forcing may be up to eight or ten times normal which means for a 300 volt dc supply the actual voltage could be up to 200Q volts dc or even 300Q volts dc. Thus the field supply must be able to pxovide a voltage of either polarity at any given time. It is common practice to use a phase controlled converter having two quadrant operation. A
description of such a phase controlled converter may be found, for example, in the text book "Thyristor Phase~Controlled Converters and Cycloconverters" by B.R. Pelly, Wiley-Interscience, 1971, Chapter 3.
It is therefore not practical to place dropping resistors across the field to try to obtain a supply of 24 volts for auxiliary equipment on the , :~
Case ~846 rotor. It is, in fact, difficult to obtain a unipolar supply of ~24 volts dc by any means from a field supply which may be of either polarity with a value of perhaps 3000 volts peak to peak negative to positive.
In a field current power supply using phase controlled SCRs, each time the SCRs are turned on or start to conduct at a time later than the time the voltage is available to cause conduction, there is a rapid change which generates high frequency components which appear to extend into the 50 Khz range. These high frequency components or disturbances in the unfiltered field supply are undesirable ox at least unnecessary insofar as the operation of the generator i5 concerned, by they can be used by the apparatus of the invention to provide a source of auxiliary power.
SUMMARY OF THE INVENTION
The present invention makes use of high frequency ac components present in the field supply to the rotor field windings. These high frequency ~O components are present when there i5 a current regulated field supply and the regulation is electronic regulation. The apparatus of this invention would not function if all the high frequency components were eliminated from the field supply, for example by extensive high frequency filtering.
However, it is an unnecessary expense to provide high frequency filtering for a generator field supply when such filtering has no practical value.
The apparatus of this invention has a high frequency transformer (sometimes ref~rred to as a pulse transformer) with two windings. The first winding is connected in series with a high voltage capacitance across the field supply on the rotor of a generator. The second winding is connected to a rectifier. The rectifier output is preferably filtered and has a current limiting device and a Case 2846 voltage control device. The limited and controlled output may be used to keep a battery fully charged to power auxiliary equipment.
It i5 another object of the invention to provide a source o~ auxiliary power on the rotor of a generator, where the source utili7es high ~requency ac components in the electrical supply to the generator field winding where the ac components are largely created by the switching in an electronically regulated field supply~
Accordingly there is provided a power supply for the rotor of a generator having a field winding on the rotor and a source of power for the field winding having high frequency ac components comprising a high frequency transformer having a first and a second winding, a capacitor for connection in series with said first winding across said field supply of saicl rotor, a rectifier connected to said second winding and rectifying ac voltages from said second winding, and ~ilter means connected to said rectifier to filter the rectified voltages from said rectifier and provide a source of power for auxiliary equipment on said rotor.
It is therefore an object of the invention to provide an improved auxiliary power supply for mounting on the rotor of a generator.
BRIEF DESCRIPTION OE' THE DRAWINGS
Figure 1 is a simplified schematic drawing showing the invention, and Figures 2 and 3 are graphs of voltaye plotted against time showing an example of a partial cycle of voltage in the converter providing the field supply and the input of the supply of the invention.
Case 2~46 DESCRIPTION OF TH~ PREF~:RRED EM~3ODIM:~NT
Referxlny to ~igure 1 there is shown a schematic drawing having conductors 10 and 11 on the rotor of a generator which conduct current to the rotor field windings (not shown). Across conductors 10 and 11 a capacitor 12 and a winding 14 of transformer 15 are connected in series. The capacitor 12 must have a high voltage rating sufficient to withstand the forcing voltages which may be applied to conductors 10 and 11 to force a desired field current through the field winding, and consequently it may in practice be several capacitors in series.
Transformer 15 is a high frequency transformer preferably capable of handling frequencies which extend to at least several kilohertz. ~le winding 16 of transformer 15 is connected to a bridge rectifier 17. The individual rectifiers used in the bridge rectifier 17 are high speed rectifiers, for example type A115 (G~neral Electric Company). The output of bridge rectifier 17 is on conductors 18 and 20 and capacitors 21 and 22 are connected across this output. Capacitor 21 is to pass high frequency transients and may be of the order of 0.33 ufd.
Capacitor 22 is a filter capacitor and may be of the order of 5500 ufd at 75 volts dc. A zener diode 23 and a capacitor 24 are connected across conductors 18 and 20. The zener diode 23 is selected to break down at a voltage which is very generally about twice the desired ou~put voltage of the power supply. More specifically, the zener diode 23 is selected to have a breakdown voltage which will protect the three terminal regulators used in the following circuitry and described subsequently. If the desired power supply voltage is 24 volts dc, the zener diode might have a breakdown voltage of the order of 51 volts. A
resistor 25 connects the junction of zener diode 23
2~3 Case ~846 ~7--and capacitor 24 to the base of $he transistor 26. A
resistor 27 connects the collector to conductor 18 and the emitter of transistor 26 is connected to conductor 20. When zener diode 23 breaks down the transistor 26 is switched on causing current to flow through resistor 27 and transistor 26 to drop the voltage across conductors 18 and 20.
Conductor 18 is connected to a three terminal integrated circuit connected as a current limiter 28. The output terminal is connected through resistor 30 to another three terminal integrated circuit connected as a voltage limiter 31. The control connection for current limiter 28 is connected by conductor 32 to the input of voltage regulator 31.
A resistor network comprisiny resistors 33, 34 and 35 provides a desired control voltage on conductor 3~ for the control input of voltage regulator 310 The output from voltage regulator 31 is on conductor 37 which is connected through diode 38 to output terminal 40. A
by-pass capacitor 41 is connected between conductor 37 and conductor 20. The power supply of Figure 1 is adapted for mounting on the rotor of a generator.
While the power supply will directly power suitably rated auxiliary equipment when the generator is running and there is full voltage supplied by a phase controlled converter, it is convenient to use the supply to keep a battery in a charged condition. The battery is indicated in broken lines as 42. The battery and the supply of ~igure 1 provide power for auxiliary equipment such as measuring and tele~etry equipment. The diode 38 is to protect the apparatus i~ the battery 42 should inadvertently be connected with the incorrect polarity.
Referring for the moment to Figure 2, t~lere is shown a graph of a partial cycle of ac voltage as might appear in a field supply providing ,. , Case 284 electronically regulated power for the field winding oE a generator. The voltage increases to a point 50 at which time an SCR (not shown) in the field supply is fired, i.e., begins to conduct. A description of the operation of a phase controlled converter, which is a suitable source for field power for a generator, may be found in the aforementioned textbook "Thyristor Phase-Controlled Conveters and Cycloconverters". When conduction occurs the voltage drops very rapidly as shown. It may, of course, go negative but is shown for convenience at a zero reference. The voltage then tends to oscillate at a high frequency as at 51. ~his high frequency oscillation or high frequency ac is a component of the field voltage across conductors 10 and 11. The high frequency ac component is coupled through transformer 15 (Figure 1) and it appears across winding 16 (Figure 1) as the ac component 52 shown in Figure 3.
It will be recalled that the field voltage may take quite abrupt changes as required to force a desired field current through the field windings, and it may go negative. This does not matter insofar as the apparatus of the present invention is concerned because the apparatus uses only the high frequency ac component on the field supply.
~ eferring again to Figure 1, it is believed the operation of the power supply apparatus of the invention is clear, however it will be discussed briefly to ensure a complete understanding of the invention. There is a fluctuating voltage across conductors 10 and 11 which carry current to the field winding. ~ high frequency ac volta~e component is also present due to the rapid switchin-3 which occurs in the phase controlled conver~er supplying power for the field winding. ~apacitor 12 blocks the flow of direct current, but the ac component is able to flow 7~ ~
Case 2~46 _g_ through capacitor 12 and winding 14. This produces a voltage Oll winding 16 which may be similar to the waveform of Figure 3. This is rectified by rectifier 17 and filtered. Any voltage fluctuations on conductor 18 which exceed the level set by zener diode 23 will trigger transistor 26 to conduct and thereby reduce the voltage. The supply includes a current limiter and a voltage regulator. The output terminals will therefore have a voltage regulated output whose current is limited.
One example of a typical supply used the following co~ponents:
capacitor 22 - 5500 ~fd at 75 volts resistor 27 - 10 ohm, 20 watt transistor 26 - 2N6249 resistor 25 - 100 ohm diode 23 - lN5368 current limiter 28 - LM317HV
voltage regulator 31 - LM317HV
resistor 30 - one ohm, two watt resistor 33 - 240 ohm resisitor 34 - 5430 (adjust) resistor 35 - 5.1 K (adjust) diode 38 - lN5624 capacitor 41 - 1.0 ~fd It will, of course, be apparent that the values given above are by way of example and that other values would be used to obtain different characteristics. It is, of course, possible to use different circuitry for limiting and controlling the operation of the auxiliary power supply according to the invention.
resistor 27 connects the collector to conductor 18 and the emitter of transistor 26 is connected to conductor 20. When zener diode 23 breaks down the transistor 26 is switched on causing current to flow through resistor 27 and transistor 26 to drop the voltage across conductors 18 and 20.
Conductor 18 is connected to a three terminal integrated circuit connected as a current limiter 28. The output terminal is connected through resistor 30 to another three terminal integrated circuit connected as a voltage limiter 31. The control connection for current limiter 28 is connected by conductor 32 to the input of voltage regulator 31.
A resistor network comprisiny resistors 33, 34 and 35 provides a desired control voltage on conductor 3~ for the control input of voltage regulator 310 The output from voltage regulator 31 is on conductor 37 which is connected through diode 38 to output terminal 40. A
by-pass capacitor 41 is connected between conductor 37 and conductor 20. The power supply of Figure 1 is adapted for mounting on the rotor of a generator.
While the power supply will directly power suitably rated auxiliary equipment when the generator is running and there is full voltage supplied by a phase controlled converter, it is convenient to use the supply to keep a battery in a charged condition. The battery is indicated in broken lines as 42. The battery and the supply of ~igure 1 provide power for auxiliary equipment such as measuring and tele~etry equipment. The diode 38 is to protect the apparatus i~ the battery 42 should inadvertently be connected with the incorrect polarity.
Referring for the moment to Figure 2, t~lere is shown a graph of a partial cycle of ac voltage as might appear in a field supply providing ,. , Case 284 electronically regulated power for the field winding oE a generator. The voltage increases to a point 50 at which time an SCR (not shown) in the field supply is fired, i.e., begins to conduct. A description of the operation of a phase controlled converter, which is a suitable source for field power for a generator, may be found in the aforementioned textbook "Thyristor Phase-Controlled Conveters and Cycloconverters". When conduction occurs the voltage drops very rapidly as shown. It may, of course, go negative but is shown for convenience at a zero reference. The voltage then tends to oscillate at a high frequency as at 51. ~his high frequency oscillation or high frequency ac is a component of the field voltage across conductors 10 and 11. The high frequency ac component is coupled through transformer 15 (Figure 1) and it appears across winding 16 (Figure 1) as the ac component 52 shown in Figure 3.
It will be recalled that the field voltage may take quite abrupt changes as required to force a desired field current through the field windings, and it may go negative. This does not matter insofar as the apparatus of the present invention is concerned because the apparatus uses only the high frequency ac component on the field supply.
~ eferring again to Figure 1, it is believed the operation of the power supply apparatus of the invention is clear, however it will be discussed briefly to ensure a complete understanding of the invention. There is a fluctuating voltage across conductors 10 and 11 which carry current to the field winding. ~ high frequency ac volta~e component is also present due to the rapid switchin-3 which occurs in the phase controlled conver~er supplying power for the field winding. ~apacitor 12 blocks the flow of direct current, but the ac component is able to flow 7~ ~
Case 2~46 _g_ through capacitor 12 and winding 14. This produces a voltage Oll winding 16 which may be similar to the waveform of Figure 3. This is rectified by rectifier 17 and filtered. Any voltage fluctuations on conductor 18 which exceed the level set by zener diode 23 will trigger transistor 26 to conduct and thereby reduce the voltage. The supply includes a current limiter and a voltage regulator. The output terminals will therefore have a voltage regulated output whose current is limited.
One example of a typical supply used the following co~ponents:
capacitor 22 - 5500 ~fd at 75 volts resistor 27 - 10 ohm, 20 watt transistor 26 - 2N6249 resistor 25 - 100 ohm diode 23 - lN5368 current limiter 28 - LM317HV
voltage regulator 31 - LM317HV
resistor 30 - one ohm, two watt resistor 33 - 240 ohm resisitor 34 - 5430 (adjust) resistor 35 - 5.1 K (adjust) diode 38 - lN5624 capacitor 41 - 1.0 ~fd It will, of course, be apparent that the values given above are by way of example and that other values would be used to obtain different characteristics. It is, of course, possible to use different circuitry for limiting and controlling the operation of the auxiliary power supply according to the invention.
Claims (4)
1. A power supply for the rotor of a generator having a field winding on the rotor and a source of power for the field winding having high frequency ac components comprising a high frequency transformer having a first and a second winding, a capacitor for connection in series with said first winding across said field supply of said rotor, a rectifier connected to said second winding and rectifying ac voltages from said second winding, and filter means connected to said rectifier to filter the rectified voltages from said rectifier and provide a source of power for auxiliary equipment on said rotor.
2. A power supply for mounting on the rotor of a large generator to provide power for auxiliary equipment mounted on said rotor, said rotor having a field winding, and a source of power for said field winding having high frequency ac voltage components on the dc voltage from said source of power, said power supply comprising a high frequency transformer having a first and a second winding, a blocking capacitor for connection in series with said first winding across said field winding on said rotor, a full wave rectifier connected to said second winding for rectifying ac voltages from said second winding, filter means connected to said rectifier, and a voltage limiter across the filtered output to limit the voltage at the output which is a source of power for auxiliary equipment.
3. A power supply for mounting on the rotor of a large generator to provide auxiliary power to electrical equipment mounted on the rotor of said generator, said rotor having a field winding, a source of power for said field winding including phase controlled SCRs and capable of providing forcing voltages for causing rapid changes in full current whereby said source of power has high frequency ac voltage components on the dc voltage provided, said power supply comprising a high frequency transformer having a first and a second winding, a blocking capacitor for connection in series with said first winding across said field winding on said rotor, a full wave rectifier, having high speed diode rectifiers, connected to said second winding for rectifying ac voltages from said second winding and providing a rectified output, a filter connected across the rectified output from said full wave rectifier, zener diode means connected to said filter to limit the voltage provided by said rectifier to a level which will not damage the power supply, a current limiter connected to said zener diode means to limit the current from said zener diode means to a predetermined level, and a voltage limiter connected to said current limiter to limit the voltage available at the output of said power supply to a level suitable for said electrical equipment mounted on said rotor.
4. A power supply as defined in claim 3 in
4. A power supply as defined in claim 3 in
Claim 4 continued:
which said voltage limiter is a three terminal voltage regulator.
which said voltage limiter is a three terminal voltage regulator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000469644A CA1249023A (en) | 1984-12-07 | 1984-12-07 | Apparatus for auxiliary power supply from a generator field |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000469644A CA1249023A (en) | 1984-12-07 | 1984-12-07 | Apparatus for auxiliary power supply from a generator field |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1249023A true CA1249023A (en) | 1989-01-17 |
Family
ID=4129331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000469644A Expired CA1249023A (en) | 1984-12-07 | 1984-12-07 | Apparatus for auxiliary power supply from a generator field |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1249023A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996034397A1 (en) * | 1995-04-25 | 1996-10-31 | Raychem Corporation | Apparatus comprising inductive and/or power transfer and/or voltage multiplication components |
-
1984
- 1984-12-07 CA CA000469644A patent/CA1249023A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996034397A1 (en) * | 1995-04-25 | 1996-10-31 | Raychem Corporation | Apparatus comprising inductive and/or power transfer and/or voltage multiplication components |
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