CA1131308A - Electrical supply system for an internal combustion engine - Google Patents
Electrical supply system for an internal combustion engineInfo
- Publication number
- CA1131308A CA1131308A CA318,021A CA318021A CA1131308A CA 1131308 A CA1131308 A CA 1131308A CA 318021 A CA318021 A CA 318021A CA 1131308 A CA1131308 A CA 1131308A
- Authority
- CA
- Canada
- Prior art keywords
- transistor
- voltage
- output
- battery
- converter
- 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
- H02J7/14—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
- H02J7/1469—Regulation of the charging current or voltage otherwise than by variation of field
- H02J7/1492—Regulation of the charging current or voltage otherwise than by variation of field by means of controlling devices between the generator output and the battery
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/92—Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Charge By Means Of Generators (AREA)
- Control Of Eletrric Generators (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An internal combustion engine includes a flywheel-mounted permanent magnet alternator connected to a converter having gated switches operating in an on-off mode to provide a regulated voltage to a battery and electrical load power.
A voltage sensing unit which is responsive to battery volt-age is connected to a gate current transistor for continu-ously supplying gate current and turning the switches fully on and off for producing a regulated output. The sensing unit includes a minimum pulse width circuit to insure a minimum turn-on signal when power is demanded. Second gates switches function as overvoltage protectors of the crowbar shunt type. An overvoltage detector is connected to the converter output and to a second gate current transistor for supplying gate current and turning on the second gated switch means in response to a major voltage deviation.
Supression circuits reduce RFI and required withstand voltages of the switch means and the first gate current transistor.
An internal combustion engine includes a flywheel-mounted permanent magnet alternator connected to a converter having gated switches operating in an on-off mode to provide a regulated voltage to a battery and electrical load power.
A voltage sensing unit which is responsive to battery volt-age is connected to a gate current transistor for continu-ously supplying gate current and turning the switches fully on and off for producing a regulated output. The sensing unit includes a minimum pulse width circuit to insure a minimum turn-on signal when power is demanded. Second gates switches function as overvoltage protectors of the crowbar shunt type. An overvoltage detector is connected to the converter output and to a second gate current transistor for supplying gate current and turning on the second gated switch means in response to a major voltage deviation.
Supression circuits reduce RFI and required withstand voltages of the switch means and the first gate current transistor.
Description
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ELECTRICAL SUPPLY SYSTEM FO~ ~N INTERNAL COMBUSTION ENGINE
Background_of the Invention The present invention is direc~ed ~o an electric supply syste~ for an internal combustion engine and parti-~ularly an electrical power supply system utilizing apermanent magnet alternator.
In most automotive and marine internal combustion engines, a conventional field controlled alternator is coupled to the engine crankshaft through suitable pulleys, 10 - belts and the like. The alternator ro~ates at a higher speed than the engine to produce a suitable electrical supply and thus requires a belt or similar drive. The belts, of course, require maintenance and replacement.
The conventional alternator uses brushes and the like which create a potential for electrical generated spar~s.
- When employed in marine applications, the internal combustion engine is normally enclosed either within a bilge or an enclosed engine compartmen~ ~ithin which gasoline fumes may accumulate. In such engines, a fine mesh screen is, therefore, placed over the air openings of the alternator to minimize the explosion hazard.
Conventionally, a field regulator is provided for controlling of the field excitation and thereby con-trolling the output of the alternator for charging ofthe battery to a selected level.
The conventional automotive alternators, par-ticularly for marine applications, require some external source of power for field excitation to assure po~er generation as soon as ~he engine is started up.
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A purely self-excited au~omotive-type alternator will gcnerally not self-excite and build up to voltage until thc engine spced increases above a minimum RP~, and in connection with cer~ain types of marine applications, the engine may not at times be operated at such speed, for example, trolling at low speed.
A combined permanent magnet-control winding field al~ernator has also been employed to ~vercome some of the disadvantages of the conventional automotive alternator. In one approach, an output winding and a control winding is provided. The output winding typically feeds a rectifier bridge, and the bridge output is connected to supply power to the battery.
The control winding is essentially a second output winding in which current is allowed to flow in the control winding when it is desired to cu~ back on the - ampere-turns, and hence output, from the output winding.
The typical regulator senses the battery voltage at some appropriate take off point in the ship-board wiring, and allows progressively more current toflow in the control winding as the sensed voltage rises toward the selected regulation level. The drawback to this scheme is the temperature-limited output of the alternator resulting from the ~act that the alternator windings are essentially always delivering the maximum total ampere turns that can be delivered at the particu-lar speed.
Another approach makes use of a single output winding in the alternator feeding into a single-phase thyristor rectifier bridge, where again the bridge output is connected to supply power to the battery.
The control method used in this case is to utilize pulse transformer or transformers feeding triggering pulses from a gated or otherwise controlled oscillator into the thyristor gates and thereby turn on the thyristors in the bridge when power to the battery and load is demanded. Typically, the thyristors in the bridge are of the silicon controlled rectifier type, which are unidirectional type devices. The systems are relatively expensive and the bridge does not continuously conduct because forward conduction cannot begin until the oscillator delivers a positive polarity trigger current pulse into the gate of the appropriate thryristor. This may reduce the output current from 5 to 10 percent of the true maximum.
Summary of the Present Invention In one broad aspect, the invention comprehends an electrical supply system for an internal combustion engine which has a permanent magnet alternator and a battery means. The supply system includes a converter means having an input for connection to the alternator and an output for connection to the battery means. The converter means has gated switch means for turning the converter means fully on and fully off and thereby regulating the output voltage, and a sensing means connected to sense the battery voltage level and to supply turn-on power to the gated switch means. The sensing means includes a timing means responsive to the battery voltage level and is operable to continuously supply turn-on power to the gated switch means for a minimum time period.
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~ ore particularly, the timing means hold the converter conducting for a minimum period to insure conducting during both half cycles of the alternator output. The converter thus includes a full wave rectifier network including a pair of oppositely and alternately conducting arms or branches, each of which includes a high power solid state unidirectional device such as a thyristor of the silicon controlled rectifier type. Thus, thyristor is employed as a generic term to define triggered devices which have a gate input and provide conduction only when an appropriate forward voltage is impressed across main power terminals and a suitable turn-on trigger signal is applied to the gate input and such forward conduction terminates when such forward voltage is removed. The bridge network is turned full on or off in accordance with the battery voltage to provide the desired regulated output.
To prevent generation of excessive bridge network output voltages in the event the battery is disconnected while one of the bridge thyristors is turned on, a crowbar type overvoltage protection net-work is employed. Crowbar switching devices in the form of suitable thyristors are connected from each AC input terminal of the rectifier bridge network to the negative or ground terminal, such that when the crowbar devices are actuated, any positive voltage appearing on either AC input terminal will be clamped to ground. An overvoltage detector sensing circuit ~ -r ., .
connected across the bridge,n~twork output actuates the crowbar devices.
A suppression RC filter circuit is preferably connected across the output of the bridge network and S interposed ahead of the input of both the threshold sensing circuit and the voltage regulating gate current source transistor. A filter circuit is also preferably connected across the alternator output term~nals and the bridge input terminals to smooth the input wave.
The permanent magnet alternator offers many advantages for internal combustion engines and particu-larly for marine applications. The alternator may be flywheel mounted and belts, pulleys, or gears are not required to turn the alternator shaft. There are no slip rings or brushes to possibly develop sparks.
There are no separate or self-excitation problems that require added wiring to the key switch, or a "generator not charging" lamp and holder. The present invention provides a reliable and practical system by which the output of the alternator may be controlled or regulated to maintain the desired voltage output.
Brief Description of the Drawings The drawings furnished herewith illustrate a preferred construction of the presen~ invention in which the above advantages and features are clearly disclosed as well as otllers which will be clear from the following description of such embodiment.
In the drawings:
Fig. 1 is a block diagram of a permanent magnet alternator-driven power syste~ for an internal , 3~B
combustion enginc an~ inclu~e; a volt~gc conver~r ancl a voltage regulating circuit controlling ~he power flow from the permanent magnet alternator to opera~e the electrical equipment and maintain the proper voltage on a bat~ery; and Fig. 2 is a schematic circuit showing a preferred construction of the system shown in Fig. 1.
escription of the Illustrated Embodiment Referring to the drawings and particularly to Fig. 1, an electrical power system is shown for an internal combustion engine. A permanent magnet alternator unit 1 is diagrammatically illustrated coupled to be driven from an internal combustion engine
ELECTRICAL SUPPLY SYSTEM FO~ ~N INTERNAL COMBUSTION ENGINE
Background_of the Invention The present invention is direc~ed ~o an electric supply syste~ for an internal combustion engine and parti-~ularly an electrical power supply system utilizing apermanent magnet alternator.
In most automotive and marine internal combustion engines, a conventional field controlled alternator is coupled to the engine crankshaft through suitable pulleys, 10 - belts and the like. The alternator ro~ates at a higher speed than the engine to produce a suitable electrical supply and thus requires a belt or similar drive. The belts, of course, require maintenance and replacement.
The conventional alternator uses brushes and the like which create a potential for electrical generated spar~s.
- When employed in marine applications, the internal combustion engine is normally enclosed either within a bilge or an enclosed engine compartmen~ ~ithin which gasoline fumes may accumulate. In such engines, a fine mesh screen is, therefore, placed over the air openings of the alternator to minimize the explosion hazard.
Conventionally, a field regulator is provided for controlling of the field excitation and thereby con-trolling the output of the alternator for charging ofthe battery to a selected level.
The conventional automotive alternators, par-ticularly for marine applications, require some external source of power for field excitation to assure po~er generation as soon as ~he engine is started up.
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A purely self-excited au~omotive-type alternator will gcnerally not self-excite and build up to voltage until thc engine spced increases above a minimum RP~, and in connection with cer~ain types of marine applications, the engine may not at times be operated at such speed, for example, trolling at low speed.
A combined permanent magnet-control winding field al~ernator has also been employed to ~vercome some of the disadvantages of the conventional automotive alternator. In one approach, an output winding and a control winding is provided. The output winding typically feeds a rectifier bridge, and the bridge output is connected to supply power to the battery.
The control winding is essentially a second output winding in which current is allowed to flow in the control winding when it is desired to cu~ back on the - ampere-turns, and hence output, from the output winding.
The typical regulator senses the battery voltage at some appropriate take off point in the ship-board wiring, and allows progressively more current toflow in the control winding as the sensed voltage rises toward the selected regulation level. The drawback to this scheme is the temperature-limited output of the alternator resulting from the ~act that the alternator windings are essentially always delivering the maximum total ampere turns that can be delivered at the particu-lar speed.
Another approach makes use of a single output winding in the alternator feeding into a single-phase thyristor rectifier bridge, where again the bridge output is connected to supply power to the battery.
The control method used in this case is to utilize pulse transformer or transformers feeding triggering pulses from a gated or otherwise controlled oscillator into the thyristor gates and thereby turn on the thyristors in the bridge when power to the battery and load is demanded. Typically, the thyristors in the bridge are of the silicon controlled rectifier type, which are unidirectional type devices. The systems are relatively expensive and the bridge does not continuously conduct because forward conduction cannot begin until the oscillator delivers a positive polarity trigger current pulse into the gate of the appropriate thryristor. This may reduce the output current from 5 to 10 percent of the true maximum.
Summary of the Present Invention In one broad aspect, the invention comprehends an electrical supply system for an internal combustion engine which has a permanent magnet alternator and a battery means. The supply system includes a converter means having an input for connection to the alternator and an output for connection to the battery means. The converter means has gated switch means for turning the converter means fully on and fully off and thereby regulating the output voltage, and a sensing means connected to sense the battery voltage level and to supply turn-on power to the gated switch means. The sensing means includes a timing means responsive to the battery voltage level and is operable to continuously supply turn-on power to the gated switch means for a minimum time period.
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~ ore particularly, the timing means hold the converter conducting for a minimum period to insure conducting during both half cycles of the alternator output. The converter thus includes a full wave rectifier network including a pair of oppositely and alternately conducting arms or branches, each of which includes a high power solid state unidirectional device such as a thyristor of the silicon controlled rectifier type. Thus, thyristor is employed as a generic term to define triggered devices which have a gate input and provide conduction only when an appropriate forward voltage is impressed across main power terminals and a suitable turn-on trigger signal is applied to the gate input and such forward conduction terminates when such forward voltage is removed. The bridge network is turned full on or off in accordance with the battery voltage to provide the desired regulated output.
To prevent generation of excessive bridge network output voltages in the event the battery is disconnected while one of the bridge thyristors is turned on, a crowbar type overvoltage protection net-work is employed. Crowbar switching devices in the form of suitable thyristors are connected from each AC input terminal of the rectifier bridge network to the negative or ground terminal, such that when the crowbar devices are actuated, any positive voltage appearing on either AC input terminal will be clamped to ground. An overvoltage detector sensing circuit ~ -r ., .
connected across the bridge,n~twork output actuates the crowbar devices.
A suppression RC filter circuit is preferably connected across the output of the bridge network and S interposed ahead of the input of both the threshold sensing circuit and the voltage regulating gate current source transistor. A filter circuit is also preferably connected across the alternator output term~nals and the bridge input terminals to smooth the input wave.
The permanent magnet alternator offers many advantages for internal combustion engines and particu-larly for marine applications. The alternator may be flywheel mounted and belts, pulleys, or gears are not required to turn the alternator shaft. There are no slip rings or brushes to possibly develop sparks.
There are no separate or self-excitation problems that require added wiring to the key switch, or a "generator not charging" lamp and holder. The present invention provides a reliable and practical system by which the output of the alternator may be controlled or regulated to maintain the desired voltage output.
Brief Description of the Drawings The drawings furnished herewith illustrate a preferred construction of the presen~ invention in which the above advantages and features are clearly disclosed as well as otllers which will be clear from the following description of such embodiment.
In the drawings:
Fig. 1 is a block diagram of a permanent magnet alternator-driven power syste~ for an internal , 3~B
combustion enginc an~ inclu~e; a volt~gc conver~r ancl a voltage regulating circuit controlling ~he power flow from the permanent magnet alternator to opera~e the electrical equipment and maintain the proper voltage on a bat~ery; and Fig. 2 is a schematic circuit showing a preferred construction of the system shown in Fig. 1.
escription of the Illustrated Embodiment Referring to the drawings and particularly to Fig. 1, an electrical power system is shown for an internal combustion engine. A permanent magnet alternator unit 1 is diagrammatically illustrated coupled to be driven from an internal combustion engine
2. The alternator 1 may be built in~o ~he e~gine fly-wheel to form a compact direct drive. The alternatoroutput is connected to a converter 3 which is connected . to ch~rge a battery 4 and also provide power ~o the engine's ignition coil and starter, as sho~n at 5 in Fig. 2, and other shipboard auxiliary equipment 5a.
An ammeter 6 is shown connected in the positive battery lead 7 and indicates the net charging or dis-charging current flowing into or from the battery 4.
The converter 3 includes a gated bridge network 8 which rectifies the alternating current output of alternator unit 1 and provides a direct current output.
A ~oltage sensor 9 is connected to sense the voltage of battery 4 and to actuate a turn-on control 10 of gated bridge network 8 for charging of battery 4 to a selected level. An overvoltage detector 11 is connected to the output of network 8 and actuates a gated ~ 3~ ~
crowbar circuit 12 which limi~s the ou~put of ~he alternator unit 1 in the cvent the battery 4 is disconnected with the bridge turned on.
Referring particularly to ~ig. 2, the permanent magnetic alternator unit 1 is diagram-matically shown including a rotor 13 having a plurality of circumferentially spaced perma~ent magnets which produce the total magnetic field. A
multiple pole stator is wound as multiple-coil wind-ing 13a, having the individual coils connected in seriesto provide a single phase alternating voltage output connected to the inpu~ of the bridge rectifier network 8.
The alternator unit 1 is of sui~able construction and design to produce an alternating output of a sufficient power, current and voltage for sa~isfactory operation of the complete electrical system. The alternator output winding 13a is connected ~o bridge input terminals 16 and 16a.
The bridge rectifier network 8 is a full wave .20 single phase bridge which converts the alternating cur-rent at terminals 16 and 16a to a direct current at output terminals 17 and 17a. The network 8 includes a pair of power diodes 14 and 15 having their anodes connected one to each of the bridge input terminals 16 and 16a and their cathodes interconnected to each other and to the positive output terminal 17. A pair of power thyristors in the form of silicon controlled rectifiers 1~ and 19 have cathodes connected one to each of the input texminals 16 and 16a and anodes connected together and to the nega~ive output terminal 17a. In a typical intcrnal ~7-~ 8 combus~ioll ~n~ine applicati~n, the negativc terrninal17a woul~ ~e connected ~o the engine block as a co!~mon ground. The positive output lead 7 connec~s the output terminal 17 to the auxiliary cquipment and the battery 4, are returned through a ground connection.
A resistor 21 in series with a capacitor 22 is connected across the input terminals 16 and 16a and forms a suppression network which smooths the alternator voltage waveshape.
The RC network significantly lowers the peak transient forward voltage created by the inductive kick of the alternator winding on the controlled rectifier 18 or l9 when formerly conducting diode 14 or 15 abruptly achieves reverse recovery. A small capacitor connected directly across the alternator winding would tend to provide a smoother alternator voltage waveshape. However, such a . circuit would cons~itute a small capacitor discharge sub-system at the instant of bridge turn-on and aggravate the "RFI" (radio frequency interference) generated by the bridge circuit. In a marine propulsion application, the RFI signal would be transmitted over the wiring between the network 8 and the forward panel. For example, the ammeter is normally mounted as a part of the instrument panel at the steering station, while the battery 4 and regulating unit 2 and alternator 1 are mounted immediately at the internal com-bustion engine. With such a system, it, therefore, would be necessary to have a relatively long wire carrying this current from the regulator to the an~eter and back to ~he battery. In such an installation, a so~ewhat larger voltage transient on the two short alternator output wires such as --8~
13()8 associatcd witl- the RC nctwork is much lcss dc~rilnclltal than the RFI currcnt signal which would be genera~e~ on the lon~ wircs by a capacitor dischargc subsys~em.
During one hal~ cycle of the alternator output, the inpu~ terminal 16 is positive relative to terminal 16~;
diode 14 and silicon controlled rectifier or thyristor 18 are forward biased to form the conduction path ~hrough the bridge network. During the opposite half cycle, the terminal 16a is positive relative to terminal 16 and current flows through the opposite diode 15 and opposite thyristor 19. The bridge rectifier network conducts only when a forward biased thyristor 18 or 19 is ~urned on.
The thyristors 18 and 19 are turned on by gate current supplied to a gate by the bridge turn-on contr,ol circuit 10. The bridge network 8 turns itself off when the forward voltage across the conducting thyristor reverses and gate current is no longer provided by the drive circuit 10 to turn on the other thyristor. In ~he illustrated embodi-ment of the present invention, the bridge network 8 is either wholly on or wholly off and thus provides simple on-off control of the output current for charging of the battery 4 to the desired voltage level.
The control circuit lO and the ~ervolta~e detect network ll are essentially connected across the output of the bridge network 8. Specifically, an RFI suppressor circuit in the form of a resistor-capacitor pi-section filter is connected to bridge output leads 23 and 24. The control circuit 10 and overvoltage detect network ll are connected across filter output leads 23' and 24. Tlle suppressor circuit includes a series connec~ed resistor 25 11;~1 3~
connccted in le~ld 23. A ca~acitor 26 is connected between thc resistor 25 and gr~und lcad 24. The small capaci~or 27 constitutes one suppressor connected directly across thc bridge output and thc resistor 25 with larger capacitor 26 consti~utes a second suppressor. Resistor 25 prevents ringing in capacitor 26. The capacitors 26 and 27 are of extended foil or similar very low series inductance construction.
Before proceeding with the regulating operation of the circuit, the crow bar circuit 12 is described.
This circuit includes a pair of crowbar thyristors in the form of silicon controlled rectifiers 28 and 29 functioning as triggered switch means which are connected one each in parallel with the bridge network thyristors 18 and 19.
When crowbar thyristors 28 and 29 receive gate current, the appropriate one turns on and effectively shorts to ground that alternator output wire that was carrying the positive potential at that moment. If the bridge network is deliv~ring output current and the circuit breaker should trip, a harness or connector accidentally open, or a battery ~able becomes loose or corrodes open, the output voltage would no longer be limited by the clamping action of the battery. The output voltage of the network 8 would then rise to as high as the alternator 2~ unit can drive the remaining connected loads, at least for the remainder of that half cycle of alternator output.
This transient voltage is roughly equivalent to the power-ful "load-dump" transient associated with the conventional belt-drivcn alternator. Such voltagc would probably severely damage or destroy the auxiliary equipment, even 11 ~1 3()8 though tllc sig~ l would last f(r only the rcm.linder of the then conductillg half cycle, or at most for another one or ~wo half cycles. Thus, af~er ~he half cycle with ~lle ba~tery eEfectively disconnected, the bridge network is automatically turned off completely, because bridge ~urn-on control circuit 10 is dependent on battery voltage for its output.
To prevent damage from such transient fault signal, the crowbar thyristors 28 and 29 should turn on very quickly. This, in turn, requires a powerful gate pulse to the thyristors 28 and 29 so that thPy will rapidly turn on over a large area of the semiconductor chip and accept the current which is at that instant flowing out of alternator on one of the two alternator output leads and pass such current harmlessly to ground.
In the illustr~ted embodiment o this invention, the suppressor connected across the output of the bridge network 8, comprised of suppressor components 25, 26 and 27, has a second function; namely, that of a low-pass pi-section filter. Typical time constant value for resistor 25 and capacitor 26 is approximately 4 microseconds. Con-sequently, while there is effective filtering of very low energy sub-micro~econd voltage spikes, there is essentially no effect on the much slower rising "load-dump" voltage transient.
Therefore, the overvoltage detect circ~it 12 and in particular branch 30 of circuit 12, may be considered to be sensing bridge network output voltage on leads 23 and 24, the latter voltage being merely stripped of any low-energy short-duration voltage spikes.
~ 3~8 This makes thc overvoltage dc~cc~ circuit in-scnsi~ive to ~ny harml.ess low-cnergy voltage transicnts, and prevents ~he crowbar thyris~ors from being tri~gered unnecessarily.
The overvoltage detect branch 30 includes a gate current source transistor 31, connected essentially in series between the positive bridge output lead 23 and the gatcs 32 and 33 of crowbar thyristors 28 and 29. Cur-ren~ limiting resistors 34 and 35 are connected one each in series with each of the ga~es 32 and 33.
A transistor 38 is connected to the resistors 36 and 37 to function as a very-low current ~ener diode.
Thus, the emitter 39 is connected to the junction of the resistors 36 and 37 and the base 40 is connected in series with a resistor 41 to the ground lead 24. The resistor 41 is connected in turn across the base and emitter terminals of a control transistor 42 which has its emitter connected directly to the ground lead 24 and i~s collector connected in series ~ith a pair of resistors 43 and 44 to the posi-tive lead 23'. The base and emitter terminals of the gate . . current source transistor 31 is connected across xesistor 44 to provide turn on bias current to transistor 31 from the ground lead 24 when control transistor 42 turns on.
The collector of transistor 31 is not only connected via resistors 34 and 35 to the ga~es of the crowbar thyristors ~8 and 29 but is also connected by a positive feedback coupling capacitor 46 in series with a resistor 47 to the junction of the voltage divider resistors 36 and 37 to create rapid turn on o~ transistors 42 and 31. If the .30 voltage across leads 23 and 24 ~ises above a selccted -12- .
11 ~1 3~
threshold level, the voltage apl~earing across resistor 37 is sufficient to cause th~ emitter-to-base breakdown voltage o~ tra~sistor 38 to be exceeded and cause trans n~ittcr 38 to supply base current to the control transistor S 42 which is selected to rapidly saturate with the current being limited by the series collector resistor 43. The base drive provided to transistor 31 by transistor 42 is designed to be able to saturate transistor 31 when ' as little as 0.25 volt of positive feedback voltage appears across resistor 47. Thus, the gate current rapidly rises in the controlled rectifiers 28 and 29, with the drive and control transistors 31 and 42 near saturation. The result will be a very rapid and large area turn-on of the crowbar controlled rectifier 28, Or 29, whichever is forward biased by the output of the alternator unit 1. Thus, the voltage limiting circuit 11 provides a means for protecting of the circuit components of the regulator as well as all of the shipboard electrical equipment for abnormal voltages associated with accidental or involuntary disconnection o~ the battery. The crowbar devices in the present inven- -tîon do no~ apply a short circuit across the bridge output, nor do they apply a short circuit across the bridge input, but rather they act as if a positive voltage clipping diode were suddenly connected from each bridge input to ground to provide shunt voltage regulation.
The overvoltage condi~ion and crowbar circuit operation is thus seen to be of momentary duration only.
Therefore, although the alternator may be able to dcliver high values of overvoltage, accompanied by si~nificantly large currents, partlcularly ~hen shorted out by a crowbar, ~ 30 ~
the mom.~rl~ary n.~Lure o~ ~he conlition allo~s thc use of cro~ar thyristors o~ lower current rating than that required for ~he bridge nctwork thyristors and diodcs.
The remaining circuitry of the converter 3 is dedicatcd to sensing battery voltage and controlling the bridge networh 8 in accordance with the actual battery voltage to maintain the proper charge in battery. ~s previously described, the rectifier network 8 is driven wholly on or wholly off by turning bridge control or drive circuit 11 on andoff. The bridge comes on in essentially instantaneous response to circuit 11 turning on. The bridge turns off at its first opportunity, i.e., alternator vol~age reversal, in response to circuit 11 turning off.
The bridge drive circuit 11 includes a gate current source transistor 48, shown as a high voltage PNP LranSistor.
The collector of transistor 48 is connected in series with a current limiting resistor 49 and a pair of steering diodes 50 and 51 to the individual gates 52 and 53 of the bridge controlled rectifiers 18 and 19. A pair of voltage dividing resistors 55 and 56 are connected in series across the voltage spike filtered bridge output lines 23' and 24, with the junction of such resistors connected to the base of the transistor 48. The current flowing through resistor 56 provides sufficient base currcnt for transistor 48 to bias the transistor to conduct at saturation level. The circuit is thus connected to provide continuously available gate curr~nt to the thyristors 18 and 19. The entire gate curren~
is automatically drawn toward that thyristor 18,or 19, which has its cathode connected to the input terminal ~ 3()8 which is il~s~antallcously at th~ more ne~a~ivc polarity o~ t~ t~o.
The ~hyristors 18 and 19 require relatively heavy gate current drive, generally on the order of 40 milliamps maxim~. Howevcr, only one of the thyristors 18 or 19 experiences a forward voltage at any given instant as a result of the connection to the opposite `sides of the alternator winding 13a. Further, the forward biased thyristor 18 or 19 automatically receives essentially all of the gate curren~ provided by the transistor 48. The transistor 48 therefore need only supply 40 milliamps multiplied by any suitable safety factor to compensate for low temperature operating conditions and with battery voltage at a minimum. A~ter the controlled rectifier 18, or 19, turns on the transis-tor 48 may continued to conduct. The current is limited by the total resistance provided by the series connected resistors 25 and 49.
The gate current source transistor 48 is turned off by a turn-off transistor 57 having its collector-to-emitter junction connected directly across the resistor 55 and therefore the emitter-to-base iunc-tion of the transistor 48. With the transistor 57 driven into saturation, the base-to-emitter current drive on the gate surrent source transistor 48 would be zero and the transistor 48 would be shut off.
The transient suppression ne~work formed by the series resistor 25 and the shunt capacitors 26 and 27 functions as previously noted to a~tenuate any positive very short-duration transient voltages. This further ~ ()8 s~bili.~ t~ oltagcs imprcs-;cd across thc gate current source transis~or 48 and Illini~lizcs the recluir~ ~osi~ivc emitter~to-negative collecto~ ~oltage rating of transistor 48. Thus, ~he collector of transistor 48 will see rela-tively higll peak negative voltages, reflected from theinstantaneous ne~ative input terminal 16-16a through the cathode to ~ate junction of thyristors 18 and 19 during normal operation of the alternator. The emitter is connect-ed to the transient-suppressed positive lead,23' which normally sees a positive volt potential. A total collector~to-emitter voltage across transistor 48 on the order of 244 volts appears across transistor 48 even without any positive voltage transients on line 23.
The suppression of positive voltage spikes so that they do not add to the 244 volts already encounterçd is but good design practice for reliable long life operation.
Thus by proper design, gate current source transistor 48 provides a means for producing instantly available and essentially constant gate drive power to the controlled rectifiers 18 and 19 which in turn will rapidly turn on and maintain full available alternator output to the circuit. As ~reviously noted, with the constantly available gate current drive, a rectified output essentially identical to that of a full diode bridge network has been obtained with the illustrated embodiment of this invention.
The turnoff or by-pass transistor 57 is con-trolled to wholly turn off the bridge ~a~e current drive when the battery voltage is at a desired maximum level.
A voltage senslng lead 58 is connected dirPctly to the .
~ 3~)8 posi~ivc ba~cly lcad a~ thc star~ solcnoid conncct:ion 59 and is com~cc~cd to actua~e a control transistor G0 in the base input circuit to transistor 57.
More particularly, a base input resistor 61 5 is connected in series with the output of control transistor 60 to the ground lead 24. A transistor 62, similar to transistor 38, is connected as a ~ener diode and connects the base of the transistor 60 to the sensing voltage lead 58 in series with a pair of resistors 63 and 63a. The illustrated element 62 is an NPN transistor ha~ing the base-emitter junction connected with reverse polarity between the base of the control transistQr 60 and the voltage signal lead 58.
A timing circuit 64, shown as a "one-shot" circuit, controls the application of the voltage level impressed on the ~.ener transistor 62. A timing reset and hold-off circuit 65 is connected to a voltage divider 66 connected between the voltage sensing lead 58 and the ground lead 24 to hold the timing means 64 in a reset state whenever battery voltage is low and thereby hold the control transistor of.
The "one-shot" circuit 64 includes a resistor . 67 in series with a timing capacitor 68 connected be-tween the emitter lead of the ~ener transistor 62 and ground lead 24. A controlled rectifier.or thyristor 69 is connected directly in parallel with the series connected resistor 67 and capacitor 68 and is operable to rapidly discharge and reset the ti~ing branch or . circuit. The gate of the thyristor 69 is connected in series with a resistor 71 to sensing lead 58. The gate .
~ 3()~
is also connectcd by a ~roundil,~ transi~or 72 ~o thc ~rou~ld lead 2~. Witl~ thc trall i5 to~ 72 cut off, ~ate currcn~ is supplied to the controlled rcctificr 69 which conducts and discharges the capacitor and thercby essentially ground the emi~tcr of the ~ener transistor 62.
The low-ohmic valued resistor 67 serves ~erely to limit the peak discharge current flowing in capacitor 68 and controlled rectifier 69 to a level consisten~ wi~h re-~iability and long life of said components. The emi~ter of transistor 62 is thus grounded and coupling transistor 60 is turned off and deprives the by-pass transistor 57 of base current. The gate current source transis~or 48 therefore is rapidly driven into saturation and supplies gate current to the controlled rectifiers 18 and lg and establishes the rectified output~ However, ~hen the gate of the timer thyristor 69 is grounded the thyristor 69 .turns off because resistor 63 is limitin~ the anode current of thyristor 69 to a level well below the re-quired grounded gate holding current. The voltage appear-ing.across ~ener transistor 62 slowly rises as capacitor 68 charges up through high ohmic valued resistor 63. ~-ener transistor 62 does not conduct however, until the capacitor voltage rises to the emitter-base breakdown value for transistor 62 ancl the turn-off action is thus delayed.
The voltage across ~ener transistor 62 is thus kept below the breakdown level for a minimum time period by the action of capacitor 68 as it recharges. The capaci-tor and resistor values are designed to hold the ~ener transistor 62 and control transistor 60 off for a selected pericd, typically 12 milliseconds, to insure an adeguate ~ 308 minimum period of ~-lll wave op,ration of the bridgc network 8 at ~he l~igher cngine speeds in particular.
The control branch 66 for tlle timing circuit includes a pair of series connected voltage sensin~
resistors 73 and 74 connectdd across the ~attery 4.
A transistor 75, connected to act as a very-low-current ~ener diode like transistor 62 and transistor 38, is connected in series with a resistor 76 between the junction of the sensing resistors 73 and 74 and the ground lead 24. A filter capacitor 77 is connected in parallel wi~h the ~ener transistor 75 and the resistor 76.
The trimmable resistor 74 determines the battery voltage necessary to cause the 2ener transistor 75 to conduct and thereby provide current to the resistor 76. The resistor 74 is a permanently fixed resistor, machine trimmed to the value necessary to calibrate the voltage sensing circuit such tha~ the desired voltage regulating level of the regulator 2 is established.
The resistor 76 is connected across the base and emitter of the grounding transistor 72. Thus, when the battery voltage rises sufficiently, ~ener transistor 75 conducts and passes current through resistor 76, thereby establishing a voltage across the base-emitter junction of grounding transistor 72.
When the battery voltage reises to or above a full charge level, the voltage across resistor 76 will attain a value suf~icient to cause current to flow through the base-emitter junction of grounding transistor 72, thereby turning it on.
When transistor 72 turns on, the gate of )8 cout-rollecl rcc~iLi~r 69 ~econlc~; ~sscntially ~roulldc~ to thc catho~c, and con~rollcd rc(~ti~ier G9 turns off ~nd initia~es the start o~ tle tllning period.
At the end of the timing period the by-pass transistor 57 is driv~n or. and turns off the ~ate current transistor 48, thereby cutting off ~he gate current drive to thyristors 18 and 19.
Upon the first alternator output ~oltage re-versal, bridge network 8 thereupon shuts off.
The reasons for the use of ~ener transistor 75 are to achieve a more sensitive, but also more stable, circuit from the standpoint of voltage regulation.
~ener transistor 75 allows calibrating resistor 74 to become somewhat higher in ohmic value than resistor 73~ thus over half of the positive poten~ial of the battery will appear at the ~unction of resistors 73 and .74.
When the battery voltage changes by a small amount~ the circuit thereor attempts to transmit a voltage change of more than half of that amount to the base of transistor 72, Of course, if transistor 72 is already drawing base current and is turned on~ the base-emitter junction drop will act as a clipper of approximately 0.6 volts and will not allow the base vol~age to increase ~ery much. A relatively large poten~ial voltage change on the base of transistor 72 will thereEore be converted instead into a relatively large change of base current into transistor 72. This accounts for the high sensitivity of the circuit.
Were ~ener transistor 75 to be replaced ~y a conducting wire, it would be n~cessary to greatly reduce the olltnic v~lue o~ resistor ,74 to a valu~ of ~ypically less than l/20th of the ohmic value of resistor 73.
The voltage at the junction of resis~ors 73 and 74 relative to ground line 24 would typically be 0.6 volts when the battery voltage is 14.3 volts.
Therefore, a change of the battery voltage by the same smal~ amount as before would tend to be trans-mitted to the base of transistor 72, but reduced by a factor greater than 20. Thus, this arrangement would be much less sensitive than the preferred arrangement.
Also, if the xener transistor 75 were to be replaced by a conducting wire and resistor 74 recalibrated downward as required, the temperature stabili~y of the regulated voltage setting would be very poor. The base-to-emitter voltage drop on a silicon transistor such as transistor 72 would typically be 0.6 volts at 25 C but would drop about .OOZ vol~s per each 1C rise.
Thus, for every 3C temperature change on transistor 72, the battery voltage regulating level would change by about one percent.
In the preferred arrangement, the presence of ~ener transistor 75 adds its voltage drop to the base-to-emitter voltage drop of transistor 72~ The temperature stability of the total voltage drop from the emitter of transistor 75 to the e~itter of transistor 72 is excellent, thus the battery voltage regulating level will remain essentially constant regardless of the temperature of the regulator unit.
After the brid~e net~ork 8 shuts off, the electrical system load is then supplied from the battery 4.
il~l308 Wh~n ~hc bat~cry VO~t.l~C drops by a small amount, the currc~nt flowing into the base of groundin~ transistor 72 ceascs, w~lich causcs tlle grounding action of transistor 72 ~o tcrminate. This allows ~atc current to flow into the gate of controlled rectifier 69 from the voltage sensing lead 58, and controlled rectifier 69 switches on rapidly and grounds the emit~er of ~ener transistor 62. This shuts off control transis~or 60.
The by-pass transis~or 57 is deprived of base current, turns off and releases the gate current source transistor 48. Base current is instantly available to drive transistor 48 into saturation and supply gate current via the steering diodes 50 and 51 to ~o~h the gates 52 and 53 of the power controlled rectifiers or thyristors 18 and 19. One of the thyristors 18 and 19 has its cathode connected to the instantaneous negative side of the alternator winding 13 and is forward biased.
The other such thyristor is reverse biased. Thus, only the forward biased thyristor receives gate current and in fact receives the full output of the gate current source transistor 48. This rapidly drives such thyristor 18 or 19 into full conduction, and make full output current of the rectifying network instantly available to charge the battery 4 and otherwise provide operatio~
- 25 essentially corresponding to that of a full wave diode bridge network. Charging will continue, of course, until the battery voltage is brought up to thc regulated level at which time the network ~ is again shut down as described previously. The time delay introduced by the "one-sllot"
circuit in the turn-off of the drive control circuit insures , ~22-~ 30~
that WllCIlCV~- outl)ut ilal; ~eell initiate~ b~ thc vol~ae rc~ulator uni~, ~he current souL-ce transistor ~8 is maintaincd o~l for a millim~ll'period su~ficiently long to create a forced full-wave opcratiun of the bride network at the high engine speeds. This maintains a balanced loacing conduction such that the bridge components operate within their rating. The even heating within the power module also minimizes the thermal stresses in the assembly and protects soldered connections.
The action of the regulator circuit is affected by the internal resistance of the battery and the resistance of the battery cables included within the voltage sensing loop, in such a way as to create a tapered charging characteristic.
When confronted by a very low battery, the regulator generally goes to con~inuous maximum output, because the low battery voltage plus the chargin~ IR
drop in the battery and its cabling, which is also being sensed, of course, is not sufficient to shut off the regulator.
As the battery comes up close to full charge, the above is not longer true. The capacitor 77 in conjunction with resistors 73, 74 and 76 and the apparent dynamic base terminal input resistance of transistor 72 acts to provide a slight filtering action on the sensed and divided battery voltage across resistor 74.
~ ith the battery in the nearly full charged condition, the bridge network is switched on and maxi~um available charging current begins to flow into the battery.
.
il;~l;3()~
The cabling IR droI) and the b~Lcry's OW~ ltcrnal I~
drop raiscs ~l~c sense~ volt~ge above tlle regulation level al~ost irmnediatcly. Tllc regulaLor tries to shut off, bu~ cannot because of the minimum time on characteristic.
Capacitor 77 builds up a slight overvoltage while w~ting for the charging to stop.
After the c~arging stops, ~he now-discharging battery drops its terminal voltage slightly., Capacitor 77 requires a sllort time to readjust back down to the appropriate new level. For part of this readjustment the règulator remains off, but then before the re-adjustment of the voltage on capacitor 77 is completed, the voltage sensing network 9 senses that more output is required, and the bridge network 8 is once a~ain switched on.
The result is a rapid succession of short . periods or bursts of maximum regulator output. As the regulator brings the battery closer and closer to full charge, the frequency of the bursts drops lower and lower, and shows up on the ammeter 7 as a lower and lower charging current. Thus, the tapered charging effect is created.
The operatlonal benefit derived from the presence of timing network 64 stems from the unexpected behavior of the permanent magnet alternator output, under half-wave rectification conditions at the higher engine speeds.
It has been found that under some conditions of high engine speed and electrical loading with t}e timing period of network 64 reduced to zero, the regulator func~
tions to allow output only on e~rery othes holf-cycle.
An ammeter 6 is shown connected in the positive battery lead 7 and indicates the net charging or dis-charging current flowing into or from the battery 4.
The converter 3 includes a gated bridge network 8 which rectifies the alternating current output of alternator unit 1 and provides a direct current output.
A ~oltage sensor 9 is connected to sense the voltage of battery 4 and to actuate a turn-on control 10 of gated bridge network 8 for charging of battery 4 to a selected level. An overvoltage detector 11 is connected to the output of network 8 and actuates a gated ~ 3~ ~
crowbar circuit 12 which limi~s the ou~put of ~he alternator unit 1 in the cvent the battery 4 is disconnected with the bridge turned on.
Referring particularly to ~ig. 2, the permanent magnetic alternator unit 1 is diagram-matically shown including a rotor 13 having a plurality of circumferentially spaced perma~ent magnets which produce the total magnetic field. A
multiple pole stator is wound as multiple-coil wind-ing 13a, having the individual coils connected in seriesto provide a single phase alternating voltage output connected to the inpu~ of the bridge rectifier network 8.
The alternator unit 1 is of sui~able construction and design to produce an alternating output of a sufficient power, current and voltage for sa~isfactory operation of the complete electrical system. The alternator output winding 13a is connected ~o bridge input terminals 16 and 16a.
The bridge rectifier network 8 is a full wave .20 single phase bridge which converts the alternating cur-rent at terminals 16 and 16a to a direct current at output terminals 17 and 17a. The network 8 includes a pair of power diodes 14 and 15 having their anodes connected one to each of the bridge input terminals 16 and 16a and their cathodes interconnected to each other and to the positive output terminal 17. A pair of power thyristors in the form of silicon controlled rectifiers 1~ and 19 have cathodes connected one to each of the input texminals 16 and 16a and anodes connected together and to the nega~ive output terminal 17a. In a typical intcrnal ~7-~ 8 combus~ioll ~n~ine applicati~n, the negativc terrninal17a woul~ ~e connected ~o the engine block as a co!~mon ground. The positive output lead 7 connec~s the output terminal 17 to the auxiliary cquipment and the battery 4, are returned through a ground connection.
A resistor 21 in series with a capacitor 22 is connected across the input terminals 16 and 16a and forms a suppression network which smooths the alternator voltage waveshape.
The RC network significantly lowers the peak transient forward voltage created by the inductive kick of the alternator winding on the controlled rectifier 18 or l9 when formerly conducting diode 14 or 15 abruptly achieves reverse recovery. A small capacitor connected directly across the alternator winding would tend to provide a smoother alternator voltage waveshape. However, such a . circuit would cons~itute a small capacitor discharge sub-system at the instant of bridge turn-on and aggravate the "RFI" (radio frequency interference) generated by the bridge circuit. In a marine propulsion application, the RFI signal would be transmitted over the wiring between the network 8 and the forward panel. For example, the ammeter is normally mounted as a part of the instrument panel at the steering station, while the battery 4 and regulating unit 2 and alternator 1 are mounted immediately at the internal com-bustion engine. With such a system, it, therefore, would be necessary to have a relatively long wire carrying this current from the regulator to the an~eter and back to ~he battery. In such an installation, a so~ewhat larger voltage transient on the two short alternator output wires such as --8~
13()8 associatcd witl- the RC nctwork is much lcss dc~rilnclltal than the RFI currcnt signal which would be genera~e~ on the lon~ wircs by a capacitor dischargc subsys~em.
During one hal~ cycle of the alternator output, the inpu~ terminal 16 is positive relative to terminal 16~;
diode 14 and silicon controlled rectifier or thyristor 18 are forward biased to form the conduction path ~hrough the bridge network. During the opposite half cycle, the terminal 16a is positive relative to terminal 16 and current flows through the opposite diode 15 and opposite thyristor 19. The bridge rectifier network conducts only when a forward biased thyristor 18 or 19 is ~urned on.
The thyristors 18 and 19 are turned on by gate current supplied to a gate by the bridge turn-on contr,ol circuit 10. The bridge network 8 turns itself off when the forward voltage across the conducting thyristor reverses and gate current is no longer provided by the drive circuit 10 to turn on the other thyristor. In ~he illustrated embodi-ment of the present invention, the bridge network 8 is either wholly on or wholly off and thus provides simple on-off control of the output current for charging of the battery 4 to the desired voltage level.
The control circuit lO and the ~ervolta~e detect network ll are essentially connected across the output of the bridge network 8. Specifically, an RFI suppressor circuit in the form of a resistor-capacitor pi-section filter is connected to bridge output leads 23 and 24. The control circuit 10 and overvoltage detect network ll are connected across filter output leads 23' and 24. Tlle suppressor circuit includes a series connec~ed resistor 25 11;~1 3~
connccted in le~ld 23. A ca~acitor 26 is connected between thc resistor 25 and gr~und lcad 24. The small capaci~or 27 constitutes one suppressor connected directly across thc bridge output and thc resistor 25 with larger capacitor 26 consti~utes a second suppressor. Resistor 25 prevents ringing in capacitor 26. The capacitors 26 and 27 are of extended foil or similar very low series inductance construction.
Before proceeding with the regulating operation of the circuit, the crow bar circuit 12 is described.
This circuit includes a pair of crowbar thyristors in the form of silicon controlled rectifiers 28 and 29 functioning as triggered switch means which are connected one each in parallel with the bridge network thyristors 18 and 19.
When crowbar thyristors 28 and 29 receive gate current, the appropriate one turns on and effectively shorts to ground that alternator output wire that was carrying the positive potential at that moment. If the bridge network is deliv~ring output current and the circuit breaker should trip, a harness or connector accidentally open, or a battery ~able becomes loose or corrodes open, the output voltage would no longer be limited by the clamping action of the battery. The output voltage of the network 8 would then rise to as high as the alternator 2~ unit can drive the remaining connected loads, at least for the remainder of that half cycle of alternator output.
This transient voltage is roughly equivalent to the power-ful "load-dump" transient associated with the conventional belt-drivcn alternator. Such voltagc would probably severely damage or destroy the auxiliary equipment, even 11 ~1 3()8 though tllc sig~ l would last f(r only the rcm.linder of the then conductillg half cycle, or at most for another one or ~wo half cycles. Thus, af~er ~he half cycle with ~lle ba~tery eEfectively disconnected, the bridge network is automatically turned off completely, because bridge ~urn-on control circuit 10 is dependent on battery voltage for its output.
To prevent damage from such transient fault signal, the crowbar thyristors 28 and 29 should turn on very quickly. This, in turn, requires a powerful gate pulse to the thyristors 28 and 29 so that thPy will rapidly turn on over a large area of the semiconductor chip and accept the current which is at that instant flowing out of alternator on one of the two alternator output leads and pass such current harmlessly to ground.
In the illustr~ted embodiment o this invention, the suppressor connected across the output of the bridge network 8, comprised of suppressor components 25, 26 and 27, has a second function; namely, that of a low-pass pi-section filter. Typical time constant value for resistor 25 and capacitor 26 is approximately 4 microseconds. Con-sequently, while there is effective filtering of very low energy sub-micro~econd voltage spikes, there is essentially no effect on the much slower rising "load-dump" voltage transient.
Therefore, the overvoltage detect circ~it 12 and in particular branch 30 of circuit 12, may be considered to be sensing bridge network output voltage on leads 23 and 24, the latter voltage being merely stripped of any low-energy short-duration voltage spikes.
~ 3~8 This makes thc overvoltage dc~cc~ circuit in-scnsi~ive to ~ny harml.ess low-cnergy voltage transicnts, and prevents ~he crowbar thyris~ors from being tri~gered unnecessarily.
The overvoltage detect branch 30 includes a gate current source transistor 31, connected essentially in series between the positive bridge output lead 23 and the gatcs 32 and 33 of crowbar thyristors 28 and 29. Cur-ren~ limiting resistors 34 and 35 are connected one each in series with each of the ga~es 32 and 33.
A transistor 38 is connected to the resistors 36 and 37 to function as a very-low current ~ener diode.
Thus, the emitter 39 is connected to the junction of the resistors 36 and 37 and the base 40 is connected in series with a resistor 41 to the ground lead 24. The resistor 41 is connected in turn across the base and emitter terminals of a control transistor 42 which has its emitter connected directly to the ground lead 24 and i~s collector connected in series ~ith a pair of resistors 43 and 44 to the posi-tive lead 23'. The base and emitter terminals of the gate . . current source transistor 31 is connected across xesistor 44 to provide turn on bias current to transistor 31 from the ground lead 24 when control transistor 42 turns on.
The collector of transistor 31 is not only connected via resistors 34 and 35 to the ga~es of the crowbar thyristors ~8 and 29 but is also connected by a positive feedback coupling capacitor 46 in series with a resistor 47 to the junction of the voltage divider resistors 36 and 37 to create rapid turn on o~ transistors 42 and 31. If the .30 voltage across leads 23 and 24 ~ises above a selccted -12- .
11 ~1 3~
threshold level, the voltage apl~earing across resistor 37 is sufficient to cause th~ emitter-to-base breakdown voltage o~ tra~sistor 38 to be exceeded and cause trans n~ittcr 38 to supply base current to the control transistor S 42 which is selected to rapidly saturate with the current being limited by the series collector resistor 43. The base drive provided to transistor 31 by transistor 42 is designed to be able to saturate transistor 31 when ' as little as 0.25 volt of positive feedback voltage appears across resistor 47. Thus, the gate current rapidly rises in the controlled rectifiers 28 and 29, with the drive and control transistors 31 and 42 near saturation. The result will be a very rapid and large area turn-on of the crowbar controlled rectifier 28, Or 29, whichever is forward biased by the output of the alternator unit 1. Thus, the voltage limiting circuit 11 provides a means for protecting of the circuit components of the regulator as well as all of the shipboard electrical equipment for abnormal voltages associated with accidental or involuntary disconnection o~ the battery. The crowbar devices in the present inven- -tîon do no~ apply a short circuit across the bridge output, nor do they apply a short circuit across the bridge input, but rather they act as if a positive voltage clipping diode were suddenly connected from each bridge input to ground to provide shunt voltage regulation.
The overvoltage condi~ion and crowbar circuit operation is thus seen to be of momentary duration only.
Therefore, although the alternator may be able to dcliver high values of overvoltage, accompanied by si~nificantly large currents, partlcularly ~hen shorted out by a crowbar, ~ 30 ~
the mom.~rl~ary n.~Lure o~ ~he conlition allo~s thc use of cro~ar thyristors o~ lower current rating than that required for ~he bridge nctwork thyristors and diodcs.
The remaining circuitry of the converter 3 is dedicatcd to sensing battery voltage and controlling the bridge networh 8 in accordance with the actual battery voltage to maintain the proper charge in battery. ~s previously described, the rectifier network 8 is driven wholly on or wholly off by turning bridge control or drive circuit 11 on andoff. The bridge comes on in essentially instantaneous response to circuit 11 turning on. The bridge turns off at its first opportunity, i.e., alternator vol~age reversal, in response to circuit 11 turning off.
The bridge drive circuit 11 includes a gate current source transistor 48, shown as a high voltage PNP LranSistor.
The collector of transistor 48 is connected in series with a current limiting resistor 49 and a pair of steering diodes 50 and 51 to the individual gates 52 and 53 of the bridge controlled rectifiers 18 and 19. A pair of voltage dividing resistors 55 and 56 are connected in series across the voltage spike filtered bridge output lines 23' and 24, with the junction of such resistors connected to the base of the transistor 48. The current flowing through resistor 56 provides sufficient base currcnt for transistor 48 to bias the transistor to conduct at saturation level. The circuit is thus connected to provide continuously available gate curr~nt to the thyristors 18 and 19. The entire gate curren~
is automatically drawn toward that thyristor 18,or 19, which has its cathode connected to the input terminal ~ 3()8 which is il~s~antallcously at th~ more ne~a~ivc polarity o~ t~ t~o.
The ~hyristors 18 and 19 require relatively heavy gate current drive, generally on the order of 40 milliamps maxim~. Howevcr, only one of the thyristors 18 or 19 experiences a forward voltage at any given instant as a result of the connection to the opposite `sides of the alternator winding 13a. Further, the forward biased thyristor 18 or 19 automatically receives essentially all of the gate curren~ provided by the transistor 48. The transistor 48 therefore need only supply 40 milliamps multiplied by any suitable safety factor to compensate for low temperature operating conditions and with battery voltage at a minimum. A~ter the controlled rectifier 18, or 19, turns on the transis-tor 48 may continued to conduct. The current is limited by the total resistance provided by the series connected resistors 25 and 49.
The gate current source transistor 48 is turned off by a turn-off transistor 57 having its collector-to-emitter junction connected directly across the resistor 55 and therefore the emitter-to-base iunc-tion of the transistor 48. With the transistor 57 driven into saturation, the base-to-emitter current drive on the gate surrent source transistor 48 would be zero and the transistor 48 would be shut off.
The transient suppression ne~work formed by the series resistor 25 and the shunt capacitors 26 and 27 functions as previously noted to a~tenuate any positive very short-duration transient voltages. This further ~ ()8 s~bili.~ t~ oltagcs imprcs-;cd across thc gate current source transis~or 48 and Illini~lizcs the recluir~ ~osi~ivc emitter~to-negative collecto~ ~oltage rating of transistor 48. Thus, ~he collector of transistor 48 will see rela-tively higll peak negative voltages, reflected from theinstantaneous ne~ative input terminal 16-16a through the cathode to ~ate junction of thyristors 18 and 19 during normal operation of the alternator. The emitter is connect-ed to the transient-suppressed positive lead,23' which normally sees a positive volt potential. A total collector~to-emitter voltage across transistor 48 on the order of 244 volts appears across transistor 48 even without any positive voltage transients on line 23.
The suppression of positive voltage spikes so that they do not add to the 244 volts already encounterçd is but good design practice for reliable long life operation.
Thus by proper design, gate current source transistor 48 provides a means for producing instantly available and essentially constant gate drive power to the controlled rectifiers 18 and 19 which in turn will rapidly turn on and maintain full available alternator output to the circuit. As ~reviously noted, with the constantly available gate current drive, a rectified output essentially identical to that of a full diode bridge network has been obtained with the illustrated embodiment of this invention.
The turnoff or by-pass transistor 57 is con-trolled to wholly turn off the bridge ~a~e current drive when the battery voltage is at a desired maximum level.
A voltage senslng lead 58 is connected dirPctly to the .
~ 3~)8 posi~ivc ba~cly lcad a~ thc star~ solcnoid conncct:ion 59 and is com~cc~cd to actua~e a control transistor G0 in the base input circuit to transistor 57.
More particularly, a base input resistor 61 5 is connected in series with the output of control transistor 60 to the ground lead 24. A transistor 62, similar to transistor 38, is connected as a ~ener diode and connects the base of the transistor 60 to the sensing voltage lead 58 in series with a pair of resistors 63 and 63a. The illustrated element 62 is an NPN transistor ha~ing the base-emitter junction connected with reverse polarity between the base of the control transistQr 60 and the voltage signal lead 58.
A timing circuit 64, shown as a "one-shot" circuit, controls the application of the voltage level impressed on the ~.ener transistor 62. A timing reset and hold-off circuit 65 is connected to a voltage divider 66 connected between the voltage sensing lead 58 and the ground lead 24 to hold the timing means 64 in a reset state whenever battery voltage is low and thereby hold the control transistor of.
The "one-shot" circuit 64 includes a resistor . 67 in series with a timing capacitor 68 connected be-tween the emitter lead of the ~ener transistor 62 and ground lead 24. A controlled rectifier.or thyristor 69 is connected directly in parallel with the series connected resistor 67 and capacitor 68 and is operable to rapidly discharge and reset the ti~ing branch or . circuit. The gate of the thyristor 69 is connected in series with a resistor 71 to sensing lead 58. The gate .
~ 3()~
is also connectcd by a ~roundil,~ transi~or 72 ~o thc ~rou~ld lead 2~. Witl~ thc trall i5 to~ 72 cut off, ~ate currcn~ is supplied to the controlled rcctificr 69 which conducts and discharges the capacitor and thercby essentially ground the emi~tcr of the ~ener transistor 62.
The low-ohmic valued resistor 67 serves ~erely to limit the peak discharge current flowing in capacitor 68 and controlled rectifier 69 to a level consisten~ wi~h re-~iability and long life of said components. The emi~ter of transistor 62 is thus grounded and coupling transistor 60 is turned off and deprives the by-pass transistor 57 of base current. The gate current source transis~or 48 therefore is rapidly driven into saturation and supplies gate current to the controlled rectifiers 18 and lg and establishes the rectified output~ However, ~hen the gate of the timer thyristor 69 is grounded the thyristor 69 .turns off because resistor 63 is limitin~ the anode current of thyristor 69 to a level well below the re-quired grounded gate holding current. The voltage appear-ing.across ~ener transistor 62 slowly rises as capacitor 68 charges up through high ohmic valued resistor 63. ~-ener transistor 62 does not conduct however, until the capacitor voltage rises to the emitter-base breakdown value for transistor 62 ancl the turn-off action is thus delayed.
The voltage across ~ener transistor 62 is thus kept below the breakdown level for a minimum time period by the action of capacitor 68 as it recharges. The capaci-tor and resistor values are designed to hold the ~ener transistor 62 and control transistor 60 off for a selected pericd, typically 12 milliseconds, to insure an adeguate ~ 308 minimum period of ~-lll wave op,ration of the bridgc network 8 at ~he l~igher cngine speeds in particular.
The control branch 66 for tlle timing circuit includes a pair of series connected voltage sensin~
resistors 73 and 74 connectdd across the ~attery 4.
A transistor 75, connected to act as a very-low-current ~ener diode like transistor 62 and transistor 38, is connected in series with a resistor 76 between the junction of the sensing resistors 73 and 74 and the ground lead 24. A filter capacitor 77 is connected in parallel wi~h the ~ener transistor 75 and the resistor 76.
The trimmable resistor 74 determines the battery voltage necessary to cause the 2ener transistor 75 to conduct and thereby provide current to the resistor 76. The resistor 74 is a permanently fixed resistor, machine trimmed to the value necessary to calibrate the voltage sensing circuit such tha~ the desired voltage regulating level of the regulator 2 is established.
The resistor 76 is connected across the base and emitter of the grounding transistor 72. Thus, when the battery voltage rises sufficiently, ~ener transistor 75 conducts and passes current through resistor 76, thereby establishing a voltage across the base-emitter junction of grounding transistor 72.
When the battery voltage reises to or above a full charge level, the voltage across resistor 76 will attain a value suf~icient to cause current to flow through the base-emitter junction of grounding transistor 72, thereby turning it on.
When transistor 72 turns on, the gate of )8 cout-rollecl rcc~iLi~r 69 ~econlc~; ~sscntially ~roulldc~ to thc catho~c, and con~rollcd rc(~ti~ier G9 turns off ~nd initia~es the start o~ tle tllning period.
At the end of the timing period the by-pass transistor 57 is driv~n or. and turns off the ~ate current transistor 48, thereby cutting off ~he gate current drive to thyristors 18 and 19.
Upon the first alternator output ~oltage re-versal, bridge network 8 thereupon shuts off.
The reasons for the use of ~ener transistor 75 are to achieve a more sensitive, but also more stable, circuit from the standpoint of voltage regulation.
~ener transistor 75 allows calibrating resistor 74 to become somewhat higher in ohmic value than resistor 73~ thus over half of the positive poten~ial of the battery will appear at the ~unction of resistors 73 and .74.
When the battery voltage changes by a small amount~ the circuit thereor attempts to transmit a voltage change of more than half of that amount to the base of transistor 72, Of course, if transistor 72 is already drawing base current and is turned on~ the base-emitter junction drop will act as a clipper of approximately 0.6 volts and will not allow the base vol~age to increase ~ery much. A relatively large poten~ial voltage change on the base of transistor 72 will thereEore be converted instead into a relatively large change of base current into transistor 72. This accounts for the high sensitivity of the circuit.
Were ~ener transistor 75 to be replaced ~y a conducting wire, it would be n~cessary to greatly reduce the olltnic v~lue o~ resistor ,74 to a valu~ of ~ypically less than l/20th of the ohmic value of resistor 73.
The voltage at the junction of resis~ors 73 and 74 relative to ground line 24 would typically be 0.6 volts when the battery voltage is 14.3 volts.
Therefore, a change of the battery voltage by the same smal~ amount as before would tend to be trans-mitted to the base of transistor 72, but reduced by a factor greater than 20. Thus, this arrangement would be much less sensitive than the preferred arrangement.
Also, if the xener transistor 75 were to be replaced by a conducting wire and resistor 74 recalibrated downward as required, the temperature stabili~y of the regulated voltage setting would be very poor. The base-to-emitter voltage drop on a silicon transistor such as transistor 72 would typically be 0.6 volts at 25 C but would drop about .OOZ vol~s per each 1C rise.
Thus, for every 3C temperature change on transistor 72, the battery voltage regulating level would change by about one percent.
In the preferred arrangement, the presence of ~ener transistor 75 adds its voltage drop to the base-to-emitter voltage drop of transistor 72~ The temperature stability of the total voltage drop from the emitter of transistor 75 to the e~itter of transistor 72 is excellent, thus the battery voltage regulating level will remain essentially constant regardless of the temperature of the regulator unit.
After the brid~e net~ork 8 shuts off, the electrical system load is then supplied from the battery 4.
il~l308 Wh~n ~hc bat~cry VO~t.l~C drops by a small amount, the currc~nt flowing into the base of groundin~ transistor 72 ceascs, w~lich causcs tlle grounding action of transistor 72 ~o tcrminate. This allows ~atc current to flow into the gate of controlled rectifier 69 from the voltage sensing lead 58, and controlled rectifier 69 switches on rapidly and grounds the emit~er of ~ener transistor 62. This shuts off control transis~or 60.
The by-pass transis~or 57 is deprived of base current, turns off and releases the gate current source transistor 48. Base current is instantly available to drive transistor 48 into saturation and supply gate current via the steering diodes 50 and 51 to ~o~h the gates 52 and 53 of the power controlled rectifiers or thyristors 18 and 19. One of the thyristors 18 and 19 has its cathode connected to the instantaneous negative side of the alternator winding 13 and is forward biased.
The other such thyristor is reverse biased. Thus, only the forward biased thyristor receives gate current and in fact receives the full output of the gate current source transistor 48. This rapidly drives such thyristor 18 or 19 into full conduction, and make full output current of the rectifying network instantly available to charge the battery 4 and otherwise provide operatio~
- 25 essentially corresponding to that of a full wave diode bridge network. Charging will continue, of course, until the battery voltage is brought up to thc regulated level at which time the network ~ is again shut down as described previously. The time delay introduced by the "one-sllot"
circuit in the turn-off of the drive control circuit insures , ~22-~ 30~
that WllCIlCV~- outl)ut ilal; ~eell initiate~ b~ thc vol~ae rc~ulator uni~, ~he current souL-ce transistor ~8 is maintaincd o~l for a millim~ll'period su~ficiently long to create a forced full-wave opcratiun of the bride network at the high engine speeds. This maintains a balanced loacing conduction such that the bridge components operate within their rating. The even heating within the power module also minimizes the thermal stresses in the assembly and protects soldered connections.
The action of the regulator circuit is affected by the internal resistance of the battery and the resistance of the battery cables included within the voltage sensing loop, in such a way as to create a tapered charging characteristic.
When confronted by a very low battery, the regulator generally goes to con~inuous maximum output, because the low battery voltage plus the chargin~ IR
drop in the battery and its cabling, which is also being sensed, of course, is not sufficient to shut off the regulator.
As the battery comes up close to full charge, the above is not longer true. The capacitor 77 in conjunction with resistors 73, 74 and 76 and the apparent dynamic base terminal input resistance of transistor 72 acts to provide a slight filtering action on the sensed and divided battery voltage across resistor 74.
~ ith the battery in the nearly full charged condition, the bridge network is switched on and maxi~um available charging current begins to flow into the battery.
.
il;~l;3()~
The cabling IR droI) and the b~Lcry's OW~ ltcrnal I~
drop raiscs ~l~c sense~ volt~ge above tlle regulation level al~ost irmnediatcly. Tllc regulaLor tries to shut off, bu~ cannot because of the minimum time on characteristic.
Capacitor 77 builds up a slight overvoltage while w~ting for the charging to stop.
After the c~arging stops, ~he now-discharging battery drops its terminal voltage slightly., Capacitor 77 requires a sllort time to readjust back down to the appropriate new level. For part of this readjustment the règulator remains off, but then before the re-adjustment of the voltage on capacitor 77 is completed, the voltage sensing network 9 senses that more output is required, and the bridge network 8 is once a~ain switched on.
The result is a rapid succession of short . periods or bursts of maximum regulator output. As the regulator brings the battery closer and closer to full charge, the frequency of the bursts drops lower and lower, and shows up on the ammeter 7 as a lower and lower charging current. Thus, the tapered charging effect is created.
The operatlonal benefit derived from the presence of timing network 64 stems from the unexpected behavior of the permanent magnet alternator output, under half-wave rectification conditions at the higher engine speeds.
It has been found that under some conditions of high engine speed and electrical loading with t}e timing period of network 64 reduced to zero, the regulator func~
tions to allow output only on e~rery othes holf-cycle.
3(~8 ~ Urtller, iL has been discovered that under such condiLions the DC ou~pu~ curr~t from the regulator is o~ e~sentially thc s~m~ magllitude as ~hat which woulcl be obtained ~ h full-wave output; i.e., output on every half cycle.
This penomenon results from magnetic flux relationships in the permanent magnet altern~tor at high speeds under the condition of half-wave vs. full-wave bridge network conduction.
When the bridge ne~work is constructed with semiconductor chip components having current ra~ings adequate for the maximum possible alternator output under high speed full-wave rectification conditions, as dictated by sound engineering practice and economics, the same semiconductor components would nevertheless be dangerously undersized for half-wave operation from the alternator in question.
Bridge networks having sufficiently large semi-conductor chip components to safely handle the 40 to 50 ampere output of the alternator in its present en~odiment are only recently availableJ and must be operated full~wave.
Even if more powerful bridge modules were avail-able, such that half-wave operation could be safely accommodated, the added cost for the increased capability of the brid~e network would be significantly greater than the preferred alternative, which is to prevent half-wave operation by the inclusion of timing network 64.
At the lower engine speeds, where the timin~
period of network 64 is not sufficient to prevent occa-sional half-wave operation, the alternator output capabili~y ~ 3~ 8 is sufficicntly lo~ so that none of the scmiconductor chips in ~llc brid~e networlc c~n be loaded bcyond their safe currerlt ra~invs.
The converter-regulator unit also permits charging of a multiplicity of ba~teries from the alternator. For example, many marine cruiscr installa-tions include one battery for operating the auxiliary equipment including lights, radio, television and the like.
A second battery is reserved for engine starting and running.
The present invention provides a voltage regula~ing system which can be easily modified to obtain a dual battery charging system in which both batteries can be charged while maintaining them separated from a load standpoint.
In this aspect of the in~ention> a diode splitter circuit is added to the system, and is connected between the positive output side of the bridge network and the several batteries with the voltage sensing network connected across one battery.
- The rectifying elements of the bridge network may produce a significant amount of heat in the semi-conductor junctions under the condition of high output current particularly, and are desirable cooled in some manner.
The cooling problem is compounded by the fact that certain of the rectifying elements are also the power flow control~ing elements, and as such must be operated at a lower maximum junction temperature than that required for rectification only.
For example, practical high current diodes should generally have a maximum operating junction temperature of 175C. However, controlled rectifiers, such as used in the bridge network for control of power flow, allow a maximum operating junction temperature of only 125C. This is to insure that when external gate current is cut off and the controlled rectifier subse-quently recovers its blocking capability, that temperature-dependent internal leakage currents do not reach a value sufficient to cause the controlled rectifier to turn itself on when forward voltage is reapplied across the anode and cathode of the device. The temperature-dependent leakage currents are held to acceptable levels by cooling the junction to 125C or less. The inventor has found that for reliable and proper operation a forced cooling of the entire bridge network 8 is desirable. In marine applications, a suitable seawater cooling passageway tube 80 is preferably provided, as diagrammatically shown in Fig. 1, for seawater cooling of the heat sensitive units.
A further feature of the illustrated circuit is that the entire regulating and control circuit has been constructed to draw a minimum current. For example, in a practical application, when the engine is shut off the entire circuit drew a mere 7 milliamps (ma) of standby current, which would not have any noticeable effect on the battery stored energy under any normal usage. The circuit does not, therefore, require any disconnect switch means and direct reliable connections may be made.
11;~13-)8 V~rious nloclcs of ca~ ryin~ out tlle invc~ ion ~rc cont~mpl;l~(l as bcin~ within the scopc of thc followitl~, cl~ims, particularly pointillg out ~nd distinctly cl~irning the sul); ect IllatLcr WlliC~I iS rcgardecl as thc invenLion.
This penomenon results from magnetic flux relationships in the permanent magnet altern~tor at high speeds under the condition of half-wave vs. full-wave bridge network conduction.
When the bridge ne~work is constructed with semiconductor chip components having current ra~ings adequate for the maximum possible alternator output under high speed full-wave rectification conditions, as dictated by sound engineering practice and economics, the same semiconductor components would nevertheless be dangerously undersized for half-wave operation from the alternator in question.
Bridge networks having sufficiently large semi-conductor chip components to safely handle the 40 to 50 ampere output of the alternator in its present en~odiment are only recently availableJ and must be operated full~wave.
Even if more powerful bridge modules were avail-able, such that half-wave operation could be safely accommodated, the added cost for the increased capability of the brid~e network would be significantly greater than the preferred alternative, which is to prevent half-wave operation by the inclusion of timing network 64.
At the lower engine speeds, where the timin~
period of network 64 is not sufficient to prevent occa-sional half-wave operation, the alternator output capabili~y ~ 3~ 8 is sufficicntly lo~ so that none of the scmiconductor chips in ~llc brid~e networlc c~n be loaded bcyond their safe currerlt ra~invs.
The converter-regulator unit also permits charging of a multiplicity of ba~teries from the alternator. For example, many marine cruiscr installa-tions include one battery for operating the auxiliary equipment including lights, radio, television and the like.
A second battery is reserved for engine starting and running.
The present invention provides a voltage regula~ing system which can be easily modified to obtain a dual battery charging system in which both batteries can be charged while maintaining them separated from a load standpoint.
In this aspect of the in~ention> a diode splitter circuit is added to the system, and is connected between the positive output side of the bridge network and the several batteries with the voltage sensing network connected across one battery.
- The rectifying elements of the bridge network may produce a significant amount of heat in the semi-conductor junctions under the condition of high output current particularly, and are desirable cooled in some manner.
The cooling problem is compounded by the fact that certain of the rectifying elements are also the power flow control~ing elements, and as such must be operated at a lower maximum junction temperature than that required for rectification only.
For example, practical high current diodes should generally have a maximum operating junction temperature of 175C. However, controlled rectifiers, such as used in the bridge network for control of power flow, allow a maximum operating junction temperature of only 125C. This is to insure that when external gate current is cut off and the controlled rectifier subse-quently recovers its blocking capability, that temperature-dependent internal leakage currents do not reach a value sufficient to cause the controlled rectifier to turn itself on when forward voltage is reapplied across the anode and cathode of the device. The temperature-dependent leakage currents are held to acceptable levels by cooling the junction to 125C or less. The inventor has found that for reliable and proper operation a forced cooling of the entire bridge network 8 is desirable. In marine applications, a suitable seawater cooling passageway tube 80 is preferably provided, as diagrammatically shown in Fig. 1, for seawater cooling of the heat sensitive units.
A further feature of the illustrated circuit is that the entire regulating and control circuit has been constructed to draw a minimum current. For example, in a practical application, when the engine is shut off the entire circuit drew a mere 7 milliamps (ma) of standby current, which would not have any noticeable effect on the battery stored energy under any normal usage. The circuit does not, therefore, require any disconnect switch means and direct reliable connections may be made.
11;~13-)8 V~rious nloclcs of ca~ ryin~ out tlle invc~ ion ~rc cont~mpl;l~(l as bcin~ within the scopc of thc followitl~, cl~ims, particularly pointillg out ~nd distinctly cl~irning the sul); ect IllatLcr WlliC~I iS rcgardecl as thc invenLion.
Claims (12)
1. An electrical supply system for an internal combustion engine having a permanent magnet alternator and a battery means, comprising a converter means having an input for connection to the alternator and an output for connection to the battery means, said converter means having gated switch means for turning the converter means fully on and fully off and thereby regulating the output voltage, and a sensing means connected to sense the battery voltage level and to supply turn-on power to said gated switch means; said sensing means including a timing means responsive to said battery voltage level and operable to continuously supply turn-on power to said gated switch means for a minimum time period.
2. The electrical supply system of Claim 1 having a gate power source including a transistor means connected to said gated switch means for supplying gate current, and said sensing means connected to turn and hold said transistor means on with said battery voltage level below a selected level.
3. The electrical supply system of Claim 2 wherein said transistor is a single high power PNP tran-sistor, diode means connecting the transistor to the gates of the gated switch means.
4. The electrical supply system of Claim 1 including a transient suppression circuit connected to the output of the converter means.
5. The system of Claim 1 including crowbar gated switch means connected in parallel with said power gated switch means, an overvoltage detect means connected to said converter means and having an output connected to turn on said crowbar switch means and being responsive to a voltage substantially above the level of said voltage sensing means.
6. The system of Claim 5 including a crowbar transistor means connected to said converter means, means connecting said crowbar transistor to the gate means of said crowbar gated switch means and operable to rapidly drive said crowbar transistor means into saturation for rapid turn on of said crowbar switch means.
7. The system of Claim 6 including transient sup-pression circuit means connected across the output of the converter means.
8. The electrical supply system of Claim 1 having lead means connected to the converter means and to battery connecting terminal means, said voltage sensing means having an input means connected to the battery con-necting terminal means to maintain full converter output to a selected battery voltage level for all lengths of said lead means.
9. The electrical supply system of Claim 1 wherein said converter means is a full wave bridge rectifier means having alternately conductive branches each of which includes a diode means and at least one of said gated switch means, said gated switch means being thyristors, said gate current source means is connected to supply gate current to said thyristors, and a filter means connected across the input of rectifier means and operable to insure turn off of the diode means when the positive polarity of the alternator decreases to zero.
10. The electrical supply system of Claim 9 having a gate current source means connected to the converter and including a gate current transistor means having an output means connected in series with the out-put of the rectifier means, means connecting said tran-sistor output to the gates of said gated switch means and providing gate current directed only to the gated switch means forward biased by the alternator, input means connected to said rectifier means and said tran-sistor means to bias said transistor on, said sensing means including a turn-off switch means connected to hold said gate current transistor means off, said timing means connected to turn said turn-off means on and off, and a voltage sensitive circuit connected to the battery terminal connection means and to the timing means to actuate the timing means in accordance with a selected battery voltage level.
11. The electrical supply system of Claim 10 including a transient suppression circuit connected in parallel with the rectifier means and said input means.
12. The apparatus of Claim 10 wherein said voltage sensitive circuit includes a calibrating and input filter means connected in parallel with an excess voltage detection circuit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US86126177A | 1977-12-16 | 1977-12-16 | |
| US861,261 | 1977-12-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1131308A true CA1131308A (en) | 1982-09-07 |
Family
ID=25335310
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA318,021A Expired CA1131308A (en) | 1977-12-16 | 1978-12-15 | Electrical supply system for an internal combustion engine |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS54109146A (en) |
| BE (1) | BE872798A (en) |
| CA (1) | CA1131308A (en) |
| NL (1) | NL7812170A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES8304374A1 (en) * | 1982-04-06 | 1983-02-16 | Motoplat | Voltage regulator |
-
1978
- 1978-12-14 NL NL7812170A patent/NL7812170A/en not_active Application Discontinuation
- 1978-12-15 BE BE192347A patent/BE872798A/en not_active IP Right Cessation
- 1978-12-15 CA CA318,021A patent/CA1131308A/en not_active Expired
- 1978-12-16 JP JP15568278A patent/JPS54109146A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| NL7812170A (en) | 1979-06-19 |
| JPS54109146A (en) | 1979-08-27 |
| BE872798A (en) | 1979-03-30 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |