GB2098764A - Control means for a battery charging system - Google Patents
Control means for a battery charging system Download PDFInfo
- Publication number
- GB2098764A GB2098764A GB8213626A GB8213626A GB2098764A GB 2098764 A GB2098764 A GB 2098764A GB 8213626 A GB8213626 A GB 8213626A GB 8213626 A GB8213626 A GB 8213626A GB 2098764 A GB2098764 A GB 2098764A
- Authority
- GB
- United Kingdom
- Prior art keywords
- thermistor
- control means
- dynamo
- voltage
- battery
- 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.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors
-
- 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
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00309—Overheat or overtemperature protection
-
- 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
- H02J7/16—Regulation of the charging current or voltage by variation of field
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Charge By Means Of Generators (AREA)
Abstract
A control means for a battery charging dynamo includes a voltage regulator having a battery-voltage sensitive input stage and an output stage 29 controlling the dynamo output. The input stage includes two parallel voltage sensing circuits (27,28 and 25,26) one of which (25,26) controls the output stage except when the thermistor (27) temperature rises above a predetermined level. The thermistor may be mounted in the dynamo to be directly sensitive to the temperature of a part thereof which can be damaged by overheating. <IMAGE>
Description
SPECIFICATION
Control means for a battery charging system
This invention relates to a control means for a battery charging system which includes a dynamo or a combined dynamo and engine starter motor.
It is an object of the invention to provide such a control means in a convenient form in which damage to the dynamo by overheating can be avoided, whilst still ensuring that battery charging can proceed at as fast a charging rate as is consistent with avoidance of heat damage to the dynamo.
Acontrol means in accordance with the invention comprises a voltage regulator having a batteryvoltage sensitive input stage and a dynamo output controlling output stage controlled by said input stage, said input stage comprising two parallel voltage sensing circuits one of which contains a thermisotr, the other of said voltage sensing circuits operating to determine the dynamo output except when the temperature of said thermistor rises above a predetermined limit.
Preferably the thermistor is a positive temperature coefficient thermistor and is connected in series with a first resistor to form said one voltage sensing circuit.
Said other voltage sensing circuit may consist of a pair of resistors in series, with their common point connected by a zener diode to a semiconductor device forming a part of the input stage of the voltage regulator, the junction of the thermistor and said first resistor being connected by a diode to said semiconductor device.
The thermistor may be mounted in the dynamo to be directly sensitive to the temperature of a part thereof which can be damaged by overheating.
A second thermistor may be connected in series with said first-mentioned thermistor and mounted to detect the temperature of a circuit element, such as a resistor or a diode, which connects the dynamo output to the battery.
In the accompanying drawings,
Figure 1 is a diagram of a battery charging system including an example of a control means in accordance with the invention; and
Figure 2 is a circuit diagram of the control means.
Figure 1 shows a combined dynamo and engine starter motor, although the invention is equally applicable to simple dynamo systems. The armature 10 of the dynamo is connected at one side to earth and at the other side, via a diode 11 to the positive terminal of a battery 12, the negative terminal of which is earthed. A series field winding 13 (used during starting) is connected in series with a starter contact 14 between said other side of the armature 10 and the positive terminal of the battery 12. The shunt field winding 15 (used during dynamo operation) is connected between said other side of the armature 10 and the output of control means 16 in the form of a voltage regulator.
Turning now to Figure 2, the voltage regulator includes an input stage which is shown in detail. This input stage includes an npn transistor 20 having its emitter grounded and its collector connected by a resistor 21 to the battery positive terminal. The base of transistor 20 is connected by a resistor 22 to ground and is also connected to the anode of a zener diode 23 and the cathode of a diode 24. The cathode of zener diode 23 is connected to the junction of two resistors 25, 26 connected in series across the battery. The anode of the diode 24 is connected by a positive temperature coefficient thermistor 27 to ground and by a resistor 28 to the positive terminal of the battery.
The output stage 29 of the voltage regulator is controlled by a transistor 20 so as to connect the winding 15 across the dynamo output when the transistor 20 is off and to disconnect it when transistor 20 is on. A capacitive positive feedback path (not shown) between the output stage and the transistor 20 may be provided in well known manner to ensure that the regulator operates in an oscillatory manner so that the power dissipation in the output stage 29 is minimised.
The thermistor 27 is mounted in the dynamo casing so as to be sensitive to the temperature of the brush assembly of the dynamo (being the part most likely to suffer heat damage). In normal operation, when no overheating is occurring, the voltage at the anode of diode 24 is relatively low, because of the low resistance of the thermistor 27 and no current can flow through the diode 24. In this condition operation of the voltage regulator is controlled by the resistors 25, 26 and the zener diode 23.Thus whenever the battery voltage rises high enough for the zener diode 23 to pass sufficient current through resistor 22 to turn the transistor 20 on charging will be interrupted, thereby regulating the battery voltage to a substantially fixed level (although temperature variations of the Vbe of transistor 20 and the and the breakdown voltage of zener diode 23 may cause some fluctuation of this voltage with ambient temperature).
In overheating conditions, which can occur, for example, when the dynamo is started up after a period of battery discharge when the open circuit battery voltage is very low, the voltage at the anode of diode 24 rises high enough for current to flow through diode 24 even when the battery voltage is too low for zener diode 23 to conduct. In these conditions the charging current is limited by regulating the battery to a lower voltage. The positive temperature coefficient thermistor used has a temperture characteristic such that its resistance changes abruptly over a small temperature range, thereby providing a good temperature limiting effect, without interfering with normal voltage regulator operation.
If desired a second thermistor (not shown) sensitive to the temperature of the diode 11 may be connected in series with the thermistor 27. Alternatively, where a reverse current cut-out is used instead of a semiconductor diode, a resistor may be connected in series with the cut-out and the second thermistor would then be in thermal contact with this resistor. In either case the second thermistor would detect the temperature rise caused by excessive current in the diode or resistor and reduce the battery voltage accordingly. Such temperature rise may occur more rapidly than the temperature rise in the brush housing.
Claims (6)
1. A control means for a battery charging system which includes a dynamo or a combined dynamo and engine starter motor, said control means comprising a voltage regulator having a battery-voltage sensitive input stage and a dynamo output controlling output stage controlled by said input stage, said input stage comprising two parallel voltage sensing circuits one of which contains a thermistor, the other of said voltage sensing circuits operating to determine the dynamo output except when the temperature of said thermistor rises above a predetermined limit.
2. A control means as claimed in Claim 1, in which said thermistor is a positive temperature coefficient thermistor and is connected in series with a first resistor to form said one voltage sensing circuit.
3. A control means as claimed in Claim 2, in which said other voltage sensing circuit comprises a pair of resistors in series, with their common point connected by a zener diode to a semiconductor device forming a part of the input stage of the voltage regulator, the junction of the thermistor and said first resistor being connected by a diode to said semiconductor device.
4. A control means as claimed in any preceding claim, in which the thermistor may be mounted in the dynamo to be directly sensitive to the tempera tureofa part thereof which can be damaged by overheating.
5. A control means as claimed in any preceding claim, in which there is a second thermistor connected in series with said first-mentioned thermistor and mounted to detect the temperature of a circuit element, such as a resistor or a diode, which connects the dynamo output to the battery.
6. A control means for a battery charging system substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8213626A GB2098764A (en) | 1982-05-11 | 1982-05-11 | Control means for a battery charging system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8213626A GB2098764A (en) | 1982-05-11 | 1982-05-11 | Control means for a battery charging system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2098764A true GB2098764A (en) | 1982-11-24 |
Family
ID=10530286
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8213626A Withdrawn GB2098764A (en) | 1982-05-11 | 1982-05-11 | Control means for a battery charging system |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2098764A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3309447A1 (en) * | 1982-03-16 | 1983-09-22 | Mitsubishi Denki K.K., Tokyo | CONTROL DEVICE FOR CONTROLLING THE OUTPUT SIGNAL OF A GENERATOR |
| DE3423891A1 (en) * | 1983-06-28 | 1985-01-03 | Mitsubishi Denki K.K., Tokio/Tokyo | CHARGING GENERATOR SYSTEM WITH A PROTECTIVE CIRCUIT |
-
1982
- 1982-05-11 GB GB8213626A patent/GB2098764A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3309447A1 (en) * | 1982-03-16 | 1983-09-22 | Mitsubishi Denki K.K., Tokyo | CONTROL DEVICE FOR CONTROLLING THE OUTPUT SIGNAL OF A GENERATOR |
| DE3309447C2 (en) * | 1982-03-16 | 1988-07-14 | Mitsubishi Denki K.K., Tokio/Tokyo, Jp | |
| DE3423891A1 (en) * | 1983-06-28 | 1985-01-03 | Mitsubishi Denki K.K., Tokio/Tokyo | CHARGING GENERATOR SYSTEM WITH A PROTECTIVE CIRCUIT |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |