GB2242764A - Electric converter - Google Patents
Electric converter Download PDFInfo
- Publication number
- GB2242764A GB2242764A GB9007946A GB9007946A GB2242764A GB 2242764 A GB2242764 A GB 2242764A GB 9007946 A GB9007946 A GB 9007946A GB 9007946 A GB9007946 A GB 9007946A GB 2242764 A GB2242764 A GB 2242764A
- Authority
- GB
- United Kingdom
- Prior art keywords
- winding
- electronic switching
- switching device
- control device
- electrical control
- 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- Withdrawn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
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
- H02J9/065—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads for lighting purposes
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/338—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement
- H02M3/3385—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in a self-oscillating arrangement with automatic control of output voltage or current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Dc-Dc Converters (AREA)
Abstract
An electrical converter comprises a magnetic element 1 such as an E core, a ring core or a rod, the magnetic element having a first winding 2, a second winding 3 and a third winding 4. The first winding is connected by way of an electronic switching device 13, such as a switching transistor or a power mosfet device, to a source of electrical power. The second winding is connected to and electrically clamped to a load 5, for example by way of a diode, and the third winding is connected to a means 7 for controlling the electronic switching device in a predetermined manner in response to an electrical signal generated in the third winding. The duty ratio and/or frequency of the electronic switching device 13 may such that the on time Ton of the electronic switching device is given by the formula: <IMAGE> where: P1 = input power V0 = output voltage L0 = inductance of second winding V1 = input voltage L1 = inductance of first winding. The converter may be used for charging a battery 5. <IMAGE>
Description
ELECTRICAL CONTROL DEVICE
The present invention relates to an electrical control device and more particularly, but not exclusively, is concerned with a battery charger for use with emergency lighting products where rechargeable battery packs are used to provide power for standby lighting in the event of mains power failure.
Battery chargers for use with such products are known and generally comprise a simple 50Hz mains step down transformer with a dissipative series element between the low voltage transformer output and the battery pack. The series element is invariably a high wattage resistor. Such a battery charger is relatively bulky and inefficient with heat being generated in both the transformer and the series resistor. In addition, once the required charge rate is determined to recover the battery pack in a given time, such as 24 hours, it then remains unchanged even when the battery is fully charged. Overcharging can lead to a reduction in battery life and there is a risk of overheating.Until recently the drawbacks of these known battery chargers have not presented a significant problem, but with increasing attention being paid to styling and in reducing overall dimensions there is clearly a need for a compact and efficient battery charger.
It is therefore an object of the present invention to provide an electrical control device such as a battery charger which meets the above requirements.
According to the present invention there is provided an electrical control device which comprises a magnetic element having a first winding, a second winding and a third winding, the first winding being connected by way of an electronic switching device to a source of electrical power, the second winding being connected to and electrically clamped to a load and the third winding being connected to a means for controlling the electronic switching device in a predetermined manner in response to an electrical signal generated in the third winding.
The magnetic element may comprise an E core, a ring core or a rod.
The electronic switching device may comprise a switching transistor or a power mosfet device.
The second winding may be connected to the load by way of a diode.
The duty ratio and/or frequency of the electronic switching device may be such that the on time TGD of the electronic switching device is given by the formula:
where:
P1 = input power VQ = output voltage L0 = inductance of second winding V1=input voltage L., = inductance of first winding.
The duty ratio and/or frequency of the electronic switching device may be such that the off time of the electronic switching device is equal to the maximum magnetic discharge period.
The duty ratio and/or frequency of the electronic switching device may be varied in dependence upon the actual magnetic discharge period represented by the electrical signal in the third winding to the off time of the electronic switching device. The duty ratio and/or frequency may be varied by means of a phase control circuit.
Alternatively or additionally, the duty ratio and/or frequency may be varied by varying the on time of the electronic switching device in dependence upon the voltage generated in the third winding.
For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying figure which is a diagrammatic representation of one embodiment of an electrical control device according to the present invention in the form of a circuit of a battery charger.
The electrical control device shown in the figure comprises a battery charger which comprises a magnetic core 1 which may be of any convenient shape. Suitable shapes for the magnetic core include an E core, a ring core or a rod. The magnetic core may be made of manganese-zinc ferrite, such as Grade F6, with a typical amplitude permeability of 1200 and saturation flux density of 450mTesla. We have obtained satisfactory results with an E core supplied by Neosid
Limited, Hertfordshire, England under Part No. 32-030-26 with an air gap of 0.2mm and wound on a bobbin supplied by
Miles Platts, Leicester, England under Part No. MP0001 with pins type 200.
Wound on the magnetic core 1 is an input winding 2, an output winding 3 and a feedback winding 4. The output winding 3 is connected directly to a battery 5 or other load by way of a diode 6. Diode 6 is a suitably rated fast recovery type diode. The input winding 2 is connected to the input source voltage Viz., while the feedback winding 4 is connected to a detection and control circuit 7 by way of a diode 8, a smoothing capacitor 9, and an attenuator formed by resistors 10 and 11.
The detection and control circuit 7 may be made up of discrete components, but may alternatively be based around a commercially available power supply integrated circuit chip such as the UC3842. The detection and control circuit 7 monitors the energy stored in the input winding 2 via a voltage sensing resistor 12 and controls the operation of an electronic switch 13. The electronic switch 13 may be, for example, a high speed switching transistor or a power mosfet.
In operation of the electrical control device, the input source voltage Vn is intermittently applied across the input winding 2 via the electronic switch 13 at a specified duty ratio of voltage on to voltage off and at a frequency controlled by the detection and control circuit 7. Energy is stored in the input winding 2 during the time the voltage is on and is monitored by the detection and control circuit. During the flyback period when the voltage is off energy is released to both the output winding 3 and the feedback winding 4. The duty ratio, peak current in the input winding 2 and the switching frequency are all determined so as to ensure the majority of the energy is transferred to the battery 5 connected to the output winding 3.
As the cycle continues over a period of time, the voltage across the battery increases and this battery voltage is forced to appear across the output winding 3 during the flyback period. The battery voltage is sensed by the feedback winding 4 and is averaged and scaled by the smoothing capacitor 9 and the attenuating resistors 10,11 and fed back to the detection and control circuit 7. The detection and control circuit 7 is configured to match the duty ratio, switching frequency and input current with the flux collapse time of the clamped output winding 3 as will be explained in more detail hereinafter.
We have found a relationship between electrical and magnetic characteristics that enables almost any magnetic material provided with three basic windings to be configured in a flyback switch mode circuit configuration which, when one winding is connected via a switching device to a source voltage and a second winding is connected via a diode to a load such as a rechargeable battery, the third winding can be used to feed a signal back to the switching device via a detection and control circuit thus providing an effective isolated charge control system with no connections from the isolated battery winding.The technique forces the load or battery characteristics onto the magnetic circuit by means of a clamp winding so that the electrical and magnetic properties of the magnetic circuit can be predicted and calculated to meet the objectives of maximum power transfer and intelligent charge control.
The principle of the circuit exploits the fact that if energy is stored in a winding (output winding 3) of a magnetic circuit and that winding is then connected to a voltage source with negligible internal impedance then the winding is effectively clamped to that voltage and in the absence of any other losses a current will flow into the battery which will reduce to zero in a linear manner and at a rate dictated by the inductance of the circuit and the clamping voltage.
Since the voltage of the battery varies during the charging process, the battery characteristic charge voltage is impressed upon the clamped output winding during the flyback period and also upon any other winding which may form part of the magnetic circuit. While the energy in the magnetic circuit is dissipating, the battery characteristic voltage and the discharge time appear in the feedback winding 4 provided the electronic switch 13 is off, the voltage in the feedback winding being dependent on the number of turns in the windings. It is therefore important to identify the magnetic discharge period and relate it to the off time of the electronic switch.
To attain the first objective of providing maximum energy transfer from the voltage source to the battery or other load with continuous inductor conduction under conditions of maximum battery charge rate, the maximum magnetic discharge period Td must be the same as the off time Toff of the electronic switch. Manufacturers data sheets for the particular battery make and type allow the selection of suitable transformer components in the normal way to meet the required power rating and frequency of operation, and the winding ratios can be selected to meet the general voltage conversion parameters for a conventional flyback convertor. These processes determine the majority of the components, but allow the frequency of the charging pulses to be varied.The on time To of the electronic switch is given by the formula:
where:
Pj = input power VO = output voltage L0 = inductance of output winding iF+ l+as
1 . .
Lj = inductance of input winding
Knowing Ton, Toff and Td permits operation of the electronic switch at a duty ratio (Ton/Toff) which provides continuous conduction at maximum charge rate and at a frequency that transfers the correct power required to the battery with the magnetic discharge period equating to the off time of the electronic switch.
To attain the second objective a means is provided to progressively reduce the charging current into the battery or other load as the battery charge capacity is approached. Because the terminal voltage of the battery is impressed upon the feedback winding 4 during the whole of the off time of the electronic switch at the point of initial charge, and the magnetic discharge period becomes shorter than the off time as the terminal voltage of the battery increases, the necessary information is already available in the feedback winding and can be rationalised and presented to the detection and control circuit 7 to adjust the battery charge current in line with the characteristics of the desired battery.
The actual construction of the detection and control circuit 7 is not critical to its function and allows the skilled person a considerable degree of flexibility.
Implementation of the circuit is largely influenced by the scale and power throughput. In one embodiment, the ratio of the magnetic discharge period represented by the electrical signal in the feedback winding to the off time of the electronic switch enables a phase control circuit to change the frequency to maintain continuous inductor conduction with the attendant advantage of low levels of electromagnetic interference and/or to change the duty ratio to give a desired charging rate. Alternatively, a high impedance control circuit can use the incremental battery or load voltage directly to change the input power by adjusting the duty ratio and/or frequency by varying the on time of the electronic switch and allowing discontinuous inductor current conduction.
We have found the electrical control device described with reference to the drawing can be used widely, from micropower circuits to applications requiring many hundreds of watts or more. It provides good electrical isolation while being small in size. A single device can be programmed to control a battery made up of any multiple of cells by simply switching in or out of circuit the relevant feedback scaling components. The device can also be programmed to provide a range of different charge rates from trickle, through normal, to fast or boost. It should be noted though, that with high charging rates, for some batteries a battery temperature monitoring circuit should be incorporated into the detection and control circuit.
A wide range of values and power ratings can be programmed into a single device with no change to the three basic windings. However, additional windings can be incorporated into the magnetic circuit for use by auxiliary circuits which have a loading which is small compared with the clamped winding.
Claims (11)
1. An electrical control device which comprises a magnetic element having a first winding, a second winding and a third winding, the first winding being connected by way of an electronic switching device to a source of electrical power, the second winding being connected to and electrically clamped to a load and the third winding being connected to a means for controlling the electronic switching device in a predetermined manner in response to an electrical signal generated in the third winding.
2. An electrical control device as claimed in claim 1, wherein the second winding is connected to and electrically clamped to the load and to the characteristics thereof.
3. An electrical control device as claimed in claim 1 or 2, wherein the magnetic element comprises an E core, a ring core or a rod.
4. An electrical control device as claimed in claim 1, 2 or 3, wherein the electronic switching device comprises a switching transistor or a power mosfet device.
5. An electrical control device as claimed in any preceding claim, wherein the second winding is connected to the load by way of a diode.
6. An electrical control device as claimed in any preceding claim, wherein the duty ratio and/or frequency of the electronic switching device is such that the on time of the electronic switching device is given by the formula:
where: P = input power
V0 = output voltage
L0 = inductance of second winding
Vj = input voltage
Lj = inductance of first winding.
7. An electrical control device as claimed in any preceding claim, wherein the duty ratio and/or frequency of the electronic switching device is such that the off time of the electronic switching device is equal to the maximum magnetic discharge period.
8. An electrical control device as claimed in any preceding claim, wherein the duty ratio and/or frequency of the electronic switching device is varied in dependence upon the actual magnetic discharge period represented by the electrical signal in the third winding to the off time of the electronic switching device.
9. An electrical control device as claimed in claim 6, 7 or 8, wherein the duty ratio and/or frequency is varied by means of a phase control circuit.
10. An electrical control device as claimed in any one of claims 6 to 9, wherein the duty ratio and/or frequency is varied by varying the on time of the electronic switching device in dependence upon the voltage generated in the third winding.
11. An electrical control device substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9007946A GB2242764A (en) | 1990-04-07 | 1990-04-07 | Electric converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9007946A GB2242764A (en) | 1990-04-07 | 1990-04-07 | Electric converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9007946D0 GB9007946D0 (en) | 1990-06-06 |
| GB2242764A true GB2242764A (en) | 1991-10-09 |
Family
ID=10674101
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9007946A Withdrawn GB2242764A (en) | 1990-04-07 | 1990-04-07 | Electric converter |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2242764A (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2151821A (en) * | 1983-12-23 | 1985-07-24 | Gen Electric Plc | Dc-dc converter |
| GB2151822A (en) * | 1983-12-23 | 1985-07-24 | Gen Electric Plc | Dc-dc converter |
| GB2166270A (en) * | 1984-10-23 | 1986-04-30 | Yokogawa Hokushin Electric | Dc/dc converter |
| US4639656A (en) * | 1984-05-04 | 1987-01-27 | Sanyo Electric Co., Ltd. | Electrical apparatus connected with a battery charger system |
| GB2179182A (en) * | 1985-08-13 | 1987-02-25 | Stc Plc | DC-DC converter |
| GB2198558A (en) * | 1986-12-08 | 1988-06-15 | Farnell Instr | Regulated power supply |
| GB2228152A (en) * | 1989-01-26 | 1990-08-15 | Mitsubishi Electric Corp | Power supply apparatus |
-
1990
- 1990-04-07 GB GB9007946A patent/GB2242764A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2151821A (en) * | 1983-12-23 | 1985-07-24 | Gen Electric Plc | Dc-dc converter |
| GB2151822A (en) * | 1983-12-23 | 1985-07-24 | Gen Electric Plc | Dc-dc converter |
| US4639656A (en) * | 1984-05-04 | 1987-01-27 | Sanyo Electric Co., Ltd. | Electrical apparatus connected with a battery charger system |
| GB2166270A (en) * | 1984-10-23 | 1986-04-30 | Yokogawa Hokushin Electric | Dc/dc converter |
| GB2179182A (en) * | 1985-08-13 | 1987-02-25 | Stc Plc | DC-DC converter |
| GB2198558A (en) * | 1986-12-08 | 1988-06-15 | Farnell Instr | Regulated power supply |
| GB2228152A (en) * | 1989-01-26 | 1990-08-15 | Mitsubishi Electric Corp | Power supply apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9007946D0 (en) | 1990-06-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Kutkut et al. | Design considerations for charge equalization of an electric vehicle battery system | |
| EP0028591B1 (en) | Method of uninterrupted operation of a current supply installation and apparatus for the method | |
| US5619403A (en) | Multi-output power supply apparatus | |
| TW285784B (en) | ||
| US5166595A (en) | Switch mode battery charging system | |
| TWI406470B (en) | Secondary side power receiving circuit of contactless power supply device | |
| US6664762B2 (en) | High voltage battery charger | |
| US4422032A (en) | Battery charging circuit for maintaining a substantially constant average value of charging current despite variations in charging voltage | |
| US6087802A (en) | Lightweight, compact, on-board electric vehicle battery charger | |
| KR20100085869A (en) | Battery charger and method for its operation | |
| US6204630B1 (en) | Lightweight, compact, on-board, electric vehicle battery charger | |
| US6600292B2 (en) | Power controller utilizing power factor correction | |
| WO2002095913A2 (en) | Power systems power circuits and components for power systems | |
| US4584514A (en) | High frequency switching battery charger | |
| US4970451A (en) | Device for utilizing low voltage electric current sources | |
| US5402055A (en) | AC adapter including differential comparator for tracking battery voltage during trickle charge | |
| US5805433A (en) | Small offline power supply | |
| EP0202579A1 (en) | Power feed apparatus for load having reverse blocking characteristics | |
| US4882663A (en) | MOSFET flyback converter | |
| KR940005457B1 (en) | Compact low noise/low power dual mode battery charging circuit | |
| JP2567034Y2 (en) | Battery charger | |
| EP1014397A1 (en) | High leakage inductor for a switched power converter | |
| EP0126936A2 (en) | High frequency switching battery charger | |
| JP3518197B2 (en) | Secondary side power receiving circuit of non-contact power supply equipment | |
| JP3238841B2 (en) | Capacitor battery charging method and charging device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |