GB2090092A - Drive circuit for eletromagnetic load - Google Patents
Drive circuit for eletromagnetic load Download PDFInfo
- Publication number
- GB2090092A GB2090092A GB8132567A GB8132567A GB2090092A GB 2090092 A GB2090092 A GB 2090092A GB 8132567 A GB8132567 A GB 8132567A GB 8132567 A GB8132567 A GB 8132567A GB 2090092 A GB2090092 A GB 2090092A
- Authority
- GB
- United Kingdom
- Prior art keywords
- inductor
- switch means
- drive circuit
- terminal
- supply
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/60—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors
- H03K17/64—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors having inductive loads
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/04—Modifications for accelerating switching
- H03K17/041—Modifications for accelerating switching without feedback from the output circuit to the control circuit
- H03K17/04113—Modifications for accelerating switching without feedback from the output circuit to the control circuit in bipolar transistor switches
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/0036—Means reducing energy consumption
Landscapes
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
A drive circuit for an electromagnetic device 15 includes an inductor 12 which can be connected across a pair of supply lines 10, 11 by way of a first switch means 13. Energy is stored in the core of the inductor which can be released into the device to cause rapid operation thereof by opening the first switch means and closing a second switch means 17. When the energy in the inductor has been dissipated a low level of current is allowed to flow into the device 15 by way of the inductor from the supply lines and this flow of current can be maintained by means of a diode 19 when the first switch means is closed to re-energise the inductor &cirf& <IMAGE>
Description
SPECIFICATION
Drive circuit
This invention relates to a drive circuit for an electromagnetic device in particular an electromagnetic actuator.
In order to improve the response time of an electromagnetic device it is possible to energise the device from a high voltage electric supply. This has the effect of speeding the build-up of electric current in the winding of the device. The provision of the high voltage electric supply presents certain problems particularly if the available supply voltage is low for example, 12-24 volts.
Moreover, the high voltage supply presents a safety hazard if it is of a permanent nature. Less of a safety hazard is present if the high voltage supply is generated only when it is required and the object of the present invention is to provide a drive circuit for an electromagnetic device in a simple and convenient form.
According to the invention a drive circuit for an electromagnetic device comprises first and second supply lines for connection to a low voltage DC supply, an inductor, first switch means operable to connect the inductor across the supply lines thereby to cause current flow through the inductor, and second switch means operable when said first switch means is opened to connect said device in a series circuit including said inductor whereby the energy stored in said inductor is utilized to initiate current flow in said device.
Examples of drive circuits in accordance with the invention will now be described with reference to the accompanying circuit diagrams. - Considering Figure 1, the circuit comprises first and second supply lines 10, 11 for connection respectively to a low voltage DC supply for example, the storage battery of a vehicle. Also provided is an iron cored inductor 12 one terminal of which is connected to the supply line 10 and the other terminal of which can be connected to the supply line 11 by way of a first switch means indicated diagrammatically at 13. The aforesaid other terminal of the inductor is connected to the anode of a diode 14.
The cathode of the diode 14 is connected to one terminal of a capacitor 1 6 the other terminal of which is connected to the supply line 11, and also to one terminal of the electromagnetic device which is to be energised this being indicated at 1 5. The other terminal of the device 1 5 can be connected by way of a second switch means 17 to the supply line 1 0. Moreover, the aforesaid other terminal of the device 17 is connected by way of a transient suppressor 1 8 to the supply line 10.
Furthermore, the anode of the diode 14 is connected to the supply line 10 by way of a diode 1 9 having its anode connected to the supply line 10.
The operation of the circuit will now be described assuming that the switch means 1 3, and 17 are open and the supply lines are connected to the storage battery. In this situation the capacitor 18 is charged by way of the inductor 12 and the diode 14. The first stage in the operation of the circuit is the closure of the switch means 13 and this allows current flow to take place in the inductor 12, the current increasing in a substantially linear fashion with time. As a result of the current flow in the winding of the inductor, energy is stored in the core of the inductor and when it is judged that sufficient energy has been stored in the inductor the first switch means 13 is opened and the second switch means 1 7 is closed.The collapse of flux in the core of the inductor 12 induces a high voltage in the associated winding and this voltage is applied to the junction of the capacitor 1 6 and device 1 5 to raise the voltage at the junction. The capacitor acts as a buffer to ensure that the voltage at the junction does not rise to an unacceptable level.
The resulting current flow through the device 1 5 takes place by way of the second switch means 17, the diode 21 and the accumulator. The rate of rise of current in the device 1 5 is high owing to the high voltage, and this leads to fast operation of the device. When substantially all the energy stored in the core of the inductor has been transferred, the current flow through the device 1 9 decreases to a lower value with the current able to flow by way of the winding of the inductor 12, and the diode 14. In practice most of the reduced current flow takes place by way of the diode 1 9.
The device is therefore maintained in an energised state under reduced power which saves energy and also minimises the heating of the winding of the device. The current flowing in the device 1 5 is determined by the internal resistance of the device.
In order to de-energise the device 1 5 the switch means 1 7 is opened and the energy stored in the winding of the device 1 5 is dissipated by way of the transient suppressor 18 and the capacitor 1 6.
The cycle as described can be repeated however, if required the switch means 13 can be closed to -recharge the inductor 12 before the switch 1 7 is opened to de-energise the device 1 5.
Referring now to Figure 2 the components which have a similar function to those of Figure 1 have the same reference numerals. In the circuit of
Figure 2 the second switch means includes a further switch 20 which is connected between the aforesaid other terminal of the device 1 5 and the anode of a diode 21 the cathode of which is connected to the supply line 10.
The circuit of Figure 2 also includes a pair of diodes 22, 23 having their cathodes connected by way of a transient suppressor 24 to the supply line 11. The anode of the diode 22 is connected to the junction of the switch means 13 and the inductor 1 2 whilst the anode of the diode 23 is connected to the junction of the switch means 17 and the device 1 5.
The operation of the circuit will now be described assuming that the switch means 1 3, 1 7 and 20 are open and the supply lines are connected to the storage battery. In this situation the capacitor 1 6 is charged by way of the inductor 12 and the diode 14. The first stage in the operation of the circuit is the closure of the switch means 1 3 to allow current flow to take place in the inductor 12, the current increasing in a substantially linear fashion with time. As a result of the current flow in the winding of the inductor, energy is stored in the core of the inductor and when it is judged that sufficient energy has been stored in the core the first switch means 1 3 is opened and the second switch means 1 7 and 20 are closed.The collapse of flux in the core of the inductor 12 induces a high voltage in the associated winding and this voltage is applied to the junction of the capacitor 1 6 and device 1 5 to raise the voltage at the junction. The capacitor acts as a buffer to ensure that the voltage at the junction does not rise to an unacceptable level.
The resulting current flow through the device 1 5 mostly takes place by way of the further switch 20 and the diode 21 although some current flow does occur through the switch means 1 7 and the accumulator. The rate of rise of current in the device 19 is high owing to the high voltage, and this leads to fast operation of the device. When substantially all the energy stored in the core of the inductor has been transferred, the current flow through the device 1 5 decreases to a lower value with the current fiowing by way of the winding of the inductor 12, the diode 14, and the switch means 17 from the storage battery. The device is therefore maintained in an energised state under reduced power which saves energy and also minimises the heating of the winding of the device.
In order to de-energise the device the switch means 17 and further switch 20 are opened and the energy stored in the winding of the device 15 is dissipated by way of the internal resistance of the device, the diode 23, the transient suppressor 24 and the capacitor 1 6. Moreover, any residual energy in the winding of the inductor is dissipated in the transient suppressor by way of the diode 22 and the storage battery. Thereafter the cycle is repeated as described.
The switch means in each example have of course been shown diagrammatically and solid state switches will be used in a practical circuit, the switches being controlled by a suitable timing circuit. In order to increase the speed of operation the iron core of the inductor may be replaced with a ferrite material.
Claims (9)
1. A drive circuit for an electromagnetic device comprising first and second supply lines for connection to a low voltage DC supply, an inductor, first switch means operable to connect the inductor across the supply lines thereby to cause current flow through the inductor and second switch means operable when said first switch means is opened to connect said device in a series circuit including said inductor whereby the energy stored in said inductor is utilized to initiate current flow in said device.
2. A drive circuit according to Claim 1 in which said first switch means is connected between said inductor and one of said supply lines, and one terminal of said device is connected to the junction of the first switch means and the inductor, the other terminal of said device being connected through said second switch means to said one supply line.
3. A drive circuit according to Claim 2 including a first diode connected between said inductor and said one terminal of the device, and a capacitor connected between said one terminal of the device and said one supply line.
4. A drive circuit according to Claim 3 including a second diode connected between said one terminal of the device and said other supply line acting when the first and second switch means are closed to maintain current flow in the device from the supply lines.
5. A drive circuit according to Claim 4 including a a transient suppressor connected between said other terminal of the device and said other supply line.
6. A drive circuit according to Claim 3 in which said second switch means includes a further switch connected between the other terminal of said device and said other supply-line and a second diode connected in series with said further switch said second diode acting to conduct upon closure of said second switch means and said further switch.
7. A drive circuit according to Claim 6 including a transient suppressor connected to said one supply line and by way of a pair of diodes respectively to the junctions of said first switch means and said inductor and said second switch means and said device.
8. A circuit according to any one of the preceding Claims in which said switch means are solid state switches controlled by a timing circuit.
9. A drive circuit for an electromagnetic device substantially as hereinbefore described with reference to Figure 1 of the accompanying circuit diagrams.
1 0. A drive circuit for an electromagnetic device substantially as hereinbefore described with reference to Figure 2 of the accompanying circuit diagrams.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8132567A GB2090092A (en) | 1980-12-09 | 1981-10-29 | Drive circuit for eletromagnetic load |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8039419 | 1980-12-09 | ||
| GB8132567A GB2090092A (en) | 1980-12-09 | 1981-10-29 | Drive circuit for eletromagnetic load |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2090092A true GB2090092A (en) | 1982-06-30 |
Family
ID=26277782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8132567A Withdrawn GB2090092A (en) | 1980-12-09 | 1981-10-29 | Drive circuit for eletromagnetic load |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2090092A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2182815A (en) * | 1985-11-12 | 1987-05-20 | Iveco Fiat | Inductive load switching circuit |
| DE19617110A1 (en) * | 1996-04-19 | 1997-10-23 | Siemens Ag | Circuit arrangement for operating an electromagnet |
-
1981
- 1981-10-29 GB GB8132567A patent/GB2090092A/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2182815A (en) * | 1985-11-12 | 1987-05-20 | Iveco Fiat | Inductive load switching circuit |
| DE3627077A1 (en) * | 1985-11-12 | 1987-05-21 | Iveco Fiat | ARRANGEMENT FOR THE FAST TRANSFER OF A CURRENT TO AN INDUCTIVE LOAD |
| FR2591045A1 (en) * | 1985-11-12 | 1987-06-05 | Iveco Fiat | DEVICE FOR QUICKLY TRANSFERRING A CURRENT IN AN INDUCTIVE LOAD |
| US4775914A (en) * | 1985-11-12 | 1988-10-04 | Iveco Fiat S.P.A. | Device for rapidly transferring current to an inductive load |
| GB2182815B (en) * | 1985-11-12 | 1989-11-01 | Iveco Fiat | Electric circuit arrangement for rapidly transferring current to an inductive load |
| DE19617110A1 (en) * | 1996-04-19 | 1997-10-23 | Siemens Ag | Circuit arrangement for operating an electromagnet |
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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) |