CN107785873B - Voltage protection circuit and method of switching power supply and switching power supply - Google Patents
Voltage protection circuit and method of switching power supply and switching power supply Download PDFInfo
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- CN107785873B CN107785873B CN201711276334.1A CN201711276334A CN107785873B CN 107785873 B CN107785873 B CN 107785873B CN 201711276334 A CN201711276334 A CN 201711276334A CN 107785873 B CN107785873 B CN 107785873B
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- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000004804 winding Methods 0.000 claims abstract description 73
- 238000002955 isolation Methods 0.000 claims abstract description 19
- 230000000087 stabilizing effect Effects 0.000 claims description 91
- 239000003990 capacitor Substances 0.000 claims description 18
- 206010063385 Intellectualisation Diseases 0.000 abstract description 3
- 230000005284 excitation Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000002159 abnormal effect Effects 0.000 description 3
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- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 1
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- 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
- H02H7/10—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 converters; for rectifiers
- H02H7/12—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 converters; for rectifiers for static converters or rectifiers
- H02H7/1213—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 converters; for rectifiers for static converters or rectifiers for DC-DC converters
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- 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
- H02M3/33507—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 with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33523—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 with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
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- 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
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a voltage protection circuit and method of a switching power supply and the switching power supply, and relates to the technical field of electric power, wherein the protection circuit comprises: a relay; the normally closed contact of the relay is arranged in a secondary side circuit of the switching power supply, and the exciting coil of the relay is electrically connected with the secondary side circuit; when the primary side winding of the transformer and the secondary side winding of the transformer are in isolation failure and the secondary side voltage on the secondary side circuit is the input voltage of the primary side winding of the transformer, the secondary side voltage is used for providing exciting voltage for the exciting coil, and the normally-closed contact is opened for cutting off the secondary side circuit. According to the voltage protection circuit, the voltage protection method and the switching power supply, when isolation failures such as short circuit and the like occur between the primary side winding and the secondary side winding of the transformer, the relay of the protection circuit cuts off the connection between the secondary side circuit and the rear-end load, so that the protection circuit can play a role in protecting the safety of experimental personnel and the rear-end load; the product intellectualization is improved, and the use feeling of a user is improved.
Description
Technical Field
The present invention relates to the field of power technologies, and in particular, to a voltage protection circuit and method for a switching power supply, and a switching power supply.
Background
The switching power supply is a power supply which uses the modern power electronic technology to control the time ratio of the switching tube to be switched on and off and maintain stable output voltage. There are various types of switching power supplies, such as forward, flyback single-ended switching power supplies, and the like. The primary winding of the transformer in the switching power supply is connected with the bus potential belonging to the strong current range, and the direct current voltage generally output by the secondary winding belongs to the weak current range. The primary side winding is isolated from the secondary side winding through magnetic coupling, and when abnormal situations such as short circuit and the like occur between the primary side winding of the transformer and the secondary side winding of the transformer, the condition that strong electricity is connected into a secondary side circuit of the switching power supply occurs, and the risk of hurting personal safety of experimental personnel exists. For example, when an experimenter is powered on to perform experiments, the experimenter often contacts with components on the secondary side of the switching power supply, and if the primary side winding of the transformer and the secondary side winding of the transformer are in short circuit, a safety accident may be caused by high direct current voltage of the bus. When an abnormal situation such as a short circuit occurs between the primary side winding of the transformer and the secondary side winding of the transformer, there is also a possibility that a load connected to the secondary side winding of the transformer breaks down. For example, the load is a signal isolation chip, when the primary side winding of the transformer and the secondary side winding of the transformer are in short circuit, the high direct current voltage of the bus is connected to the signal isolation chip along with the secondary side circuit, and if the power ground on the other side of the signal isolation chip is a bus reference point, the signal isolation chip may be broken down.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a voltage protection circuit and method for a switching power supply, and a switching power supply, which can cut off a secondary side circuit through a relay to protect the secondary side circuit when an isolation failure such as a short circuit occurs between a primary side winding and a secondary side winding of a transformer.
According to an aspect of the present invention, there is provided a voltage protection circuit of a switching power supply, comprising: a relay; the normally closed contact of the relay is arranged in a secondary side circuit of the switching power supply, and the exciting coil of the relay is electrically connected with the secondary side circuit; when the primary side winding of the transformer and the secondary side winding of the transformer are in isolation failure and the secondary side voltage on the secondary side circuit is the input voltage of the primary side winding of the transformer, the secondary side voltage is used for providing exciting voltage for the exciting coil, and the normally closed contact is opened to cut off the secondary side circuit.
Optionally, the method comprises: a voltage stabilizing circuit unit; the exciting coil is electrically connected with the secondary side circuit through the voltage stabilizing circuit unit; the secondary side voltage is an input voltage of the voltage stabilizing circuit unit, and an output voltage of the voltage stabilizing circuit unit is used for providing the exciting voltage for the exciting coil.
Optionally, the method comprises: a current limiting resistor; the voltage stabilizing circuit unit is electrically connected with the secondary side circuit through the current limiting resistor.
Optionally, the voltage stabilizing circuit unit includes: a controllable precision voltage stabilizing source; and the reference voltage output by the controllable precise voltage stabilizing source is used as the reference voltage of the output voltage.
Optionally, the voltage stabilizing circuit unit includes: the first voltage division proportioning resistor and the second voltage division proportioning resistor; the first end of the first voltage dividing ratio resistor is respectively connected with the first end of the exciting coil, the cathode of the controllable precise voltage stabilizing source and the current limiting resistor; the second end of the first voltage dividing ratio resistor is respectively connected with the reference electrode of the controllable precise voltage stabilizing source and the first end of the second voltage dividing ratio resistor; and the second end of the second voltage division proportioning resistor is respectively connected with the anode of the controllable precise voltage stabilizing source and the second end of the exciting coil.
Optionally, the output voltage V o ＝U r *(1+R 2 /R 3 ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein Ur is the reference voltage output by the controllable precise voltage stabilizing source, R 2 R is the resistance value of the first partial pressure proportioning resistor 3 And the resistance value of the second voltage division ratio resistor.
Optionally, a capacitor connected in parallel with the transformer secondary side winding is provided in the secondary side circuit, and the normally closed contact is provided between the capacitor and the transformer secondary side winding.
Optionally, the number of the normally closed contacts of the relay is two, and the two normally closed contacts are respectively arranged on a first circuit and a second circuit in the secondary side circuit, wherein the first circuit and the second circuit are respectively connected with two ends of the secondary side winding of the transformer.
According to another aspect of the present invention, there is provided a switching power supply comprising: the voltage protection circuit of the switching power supply as described above.
According to still another aspect of the present invention, there is provided a voltage protection method of a switching power supply, including: a relay is arranged, a normally closed contact of the relay is arranged in a secondary side circuit of the switching power supply, and an exciting coil of the relay is electrically connected with the secondary side circuit; when the primary side winding of the transformer and the secondary side winding of the transformer are in isolation failure, and the secondary side voltage on the secondary side circuit is the input voltage of the primary side winding of the transformer, the secondary side voltage is used for providing exciting voltage for the exciting coil, and the normally-closed contact is opened to cut off the secondary side circuit.
Optionally, a voltage stabilizing circuit unit is provided, and the exciting coil is electrically connected with the secondary side circuit through the voltage stabilizing circuit unit; the secondary side voltage is an input voltage of the voltage stabilizing circuit unit, and an output voltage of the voltage stabilizing circuit unit is used for providing the exciting voltage for the exciting coil.
Optionally, a current limiting resistor is provided, and the voltage stabilizing circuit unit is electrically connected with the secondary side circuit through the current limiting resistor.
Optionally, the voltage stabilizing circuit unit includes: a controllable precision voltage stabilizing source; and the reference voltage output by the controllable precise voltage stabilizing source is used as the reference voltage of the output voltage.
Optionally, a first voltage dividing proportioning resistor and a second voltage dividing proportioning resistor are arranged; the first end of the first voltage dividing ratio resistor is respectively connected with the first end of the exciting coil, the cathode of the controllable precise voltage stabilizing source and the current limiting resistor; the second end of the first voltage dividing ratio resistor is respectively connected with the reference electrode of the controllable precise voltage stabilizing source and the first end of the second voltage dividing ratio resistor; and the second end of the second voltage division proportioning resistor is respectively connected with the anode of the controllable precise voltage stabilizing source and the second end of the exciting coil.
Optionally, the output voltage V o ＝U r *(1+R 2 /R 3 ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein Ur is the reference voltage output by the controllable precise voltage stabilizing source, R 2 R is the resistance value of the first partial pressure proportioning resistor 3 For the second partial pressureResistance value of the proportioning resistor.
Optionally, a capacitor connected in parallel with the transformer secondary side winding is provided in the secondary side circuit, and the normally closed contact is provided between the capacitor and the transformer secondary side winding.
Optionally, the number of the normally closed contacts of the relay is two, and the two normally closed contacts are respectively arranged on a first circuit and a second circuit in the secondary side circuit, wherein the first circuit and the second circuit are respectively connected with two ends of the secondary side winding of the transformer.
According to the voltage protection circuit and method of the switching power supply and the switching power supply, the normally closed contact of the relay is arranged in the secondary side circuit, and the exciting coil is electrically connected with the secondary side circuit; when the transformer winding is in isolation failure and the secondary side voltage is the input voltage of the primary side winding of the transformer, the secondary side voltage is used for providing exciting voltage for the exciting coil, and the normally closed contact is disconnected to cut off the secondary side circuit; when isolation failures such as short circuit and the like occur between the primary side winding and the secondary side winding of the transformer, the relay of the protection circuit cuts off the connection between the secondary side circuit and the rear end load, so that the protection circuit can play a role in protecting personnel safety and the rear end load; the product intellectualization is improved, and the use feeling of a user is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort to a person skilled in the art.
FIG. 1 is a schematic diagram of one embodiment of a voltage protection circuit for a switching power supply according to the present invention;
FIG. 2 is a schematic diagram of another embodiment of a voltage protection circuit of a switching power supply according to the present invention;
FIG. 3 is a schematic diagram of an access load in one embodiment of a voltage protection circuit for a switching power supply according to the present invention;
fig. 4 is a method schematic diagram of an embodiment of a voltage protection method of a switching power supply according to the present invention.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The technical scheme of the present invention will be described in various aspects with reference to the drawings and the embodiments.
The following "first", "second", etc. are used merely to describe differences and are not otherwise specifically meant.
As shown in fig. 1, the present invention provides a voltage protection circuit of a switching power supply, which may be a single-ended switching power supply or the like. The voltage protection circuit comprises a relay KM. The relay is an electric control device, and when a change in an input amount (excitation amount) reaches a predetermined requirement, a controlled amount is changed in a predetermined step in an electric output circuit. The secondary side circuit is a weak current end of the switching power supply, and a normally closed contact S of the relay KM 1 And normally-closed contact S 2 The secondary side voltage can supply power to the exciting coil of the relay KM. The exciting coil of the relay KM and the normally-closed contact and the secondary side circuit can be arranged in various ways.
Normally closed contact S 1 And normally-closed contact S 2 The exciting coil and the normally-closed contact S are two normally-closed contacts in the relay KM 1 And normally-closed contact S 2 Are all arranged inside the relay KM. Normally closed contact S 1 And normally-closed contact S 2 Is to be used for the general purpose of (a)The breaking is controlled by the exciting coil of the relay KM, if exciting voltage is loaded on the exciting coil, the normally closed contact S 1 And normally-closed contact S 2 And (5) disconnecting.
When the primary winding 12 of the transformer and the secondary winding 13 of the transformer are in isolation failure and the secondary voltage on the secondary circuit is the input voltage of the primary winding 12 of the transformer, the secondary voltage provides exciting voltage for the exciting coil of the relay KM to open the normally closed contact S 1 And normally-closed contact S 2 The secondary side circuit is cut off to cut off the secondary side circuit, thereby achieving the protection effect.
A voltage stabilizing circuit unit 11 may be provided, and the exciting coil of the relay KM is electrically connected to the secondary side circuit through the voltage stabilizing circuit unit 11, the secondary side voltage being an input voltage of the voltage stabilizing circuit unit 11, and an output voltage of the voltage stabilizing circuit unit 11 being used to supply an exciting voltage to the exciting coil.
In one embodiment, as shown in fig. 2, the transformer may be a high frequency transformer. The secondary side circuit includes the transformer secondary winding 13 and other lines. A capacitor 17 connected in parallel with the transformer secondary winding 13 is arranged in the secondary side circuit, and the capacitor 17 is the supporting capacitor of the secondary side circuit. Normally closed contact S 1 And normally-closed contact S 2 Can be arranged between the capacitor 17 and the transformer secondary winding 13, i.e. a relay KM with a double normally closed contact is connected at the front end of the capacitor 17.
Normally closed contact S 1 And normally-closed contact S 2 The first and second lines 15 and 16 are respectively arranged on the first and second lines 15 and 16 in the secondary side circuit, and the first and second lines 15 and 16 are respectively connected with two ends of the secondary side winding 13 of the transformer.
The voltage stabilizing circuit unit can be electrically connected with the secondary side circuit through the current limiting resistor R1, and the voltage stabilizing circuit unit 11 can have various implementation manners. The voltage stabilizing circuit unit 11 includes a controllable precision voltage stabilizing source K, which may also be referred to as a precision voltage stabilizing source. The output reference voltage of the controllable precision voltage stabilizing source K can be used as the reference voltage of the output voltage of the voltage stabilizing circuit unit. There are a variety of controllable precision voltage stabilizing sources, such as TL431 and the like. Excitation coil of relay KMIs the load of the voltage stabilizing circuit unit with controllable precision voltage stabilizing source (such as TL 431) as the core. When the primary winding 12 and the secondary winding 13 of the transformer of the switching power supply are in short circuit, the input voltage of the primary winding 12 of the transformer is the bus voltage, the bus voltage is the input voltage of the voltage stabilizing circuit unit, at the moment, the output voltage Vo can energize the exciting coil of the relay KM, and the normally closed contact S is pulled open 1 And normally-closed contact S 2 The protection effect is achieved.
As shown in fig. 2, the voltage stabilizing circuit unit comprises a first voltage dividing resistor R 2 And a second voltage-dividing proportioning resistor R 3 . First voltage division proportioning resistor R 2 The first end of the exciting coil of the relay KM, the cathode of the controllable precise voltage stabilizing source K and the current limiting resistor R 1 Connection, i.e. first voltage-dividing resistor R 2 A first end of an excitation coil of a relay KM, a cathode of a controllable precise voltage-stabilizing source K and a current-limiting resistor R are connected in parallel with the first end of the excitation coil of the relay KM 1 . First voltage division proportioning resistor R 2 The second end of the resistor is respectively connected with a reference electrode of the controllable precise voltage stabilizing source K and a second voltage dividing ratio resistor R 3 Is connected with the first end of the first voltage dividing ratio resistor R 2 A reference electrode of a controllable precise voltage stabilizing source K and a second voltage dividing proportioning resistor R are connected in parallel with the second end of the voltage dividing proportioning resistor 3 Is provided.
Second voltage-dividing proportioning resistor R 3 The second ends of the two voltage-dividing resistors are respectively connected with the anode of the controllable precise voltage-stabilizing source K and the second end of the excitation coil of the relay KM, namely a second voltage-dividing proportioning resistor R 3 And the second end of the excitation coil of the relay KM is connected with the anode of the controllable precise voltage stabilizing source K in parallel. The reference point output by the voltage stabilizing circuit unit is the negative pole of the large capacitor of the bus of the switching power supply, and is GND in FIG. 2.
S is a power switch tube of the switching power supply, T is an isolation transformer, and the diode 14 is a switching power supply output rectifier diode. Terminal voltage U of primary side input large capacitor of transformer of switching power supply I I.e. the bus voltage, the P-point is the moving point of the primary winding 12 of the transformer. If 220V/50Hz mains supply is input into the switch power supply, after passing through the single-phase bridge type uncontrolled rectifying circuit, the primary side of the transformer inputs the terminal voltage U of the large capacitor I 311V (220 x 1.414).
If the circuit is abnormal, the primary winding 12 and the secondary winding 13 of the transformer are short-circuited, namely the isolation failure, up 1 Is P 1 Voltage of point relative to GND, point P and point P 1 The same point relative to GND potential is the bus voltage U I The high voltage U I May cause hidden trouble to the personal safety of the experimenters. As shown in fig. 3, a signal isolation chip connected to the back end of the secondary side circuit of the switching power supply may be broken down.
The output voltage of the voltage stabilizing circuit unit is Vo, the Vo supplies current to the exciting coil of the relay KM, and the value of the Vo can pass through the first voltage dividing and proportioning resistor R 2 And a second voltage-dividing proportioning resistor R 3 And the resistance value of the relay KM and the controllable precise voltage stabilizing source K are set, and Vo can be set to be the optimal working voltage for enabling the relay KM to act.
V o ＝U r *(1+R 2 /R 3 )(1－1)；
Ur is the reference voltage output by the controllable precision voltage stabilizing source K. Vo at second voltage division ratio resistor R 3 The divided voltage is compared with the precision voltage of the controllable precision voltage stabilizing source K, and according to the voltage error, the current flowing through the controllable precision voltage stabilizing source K can change, and finally the Vo value is regulated, so that the voltage stabilizing effect is achieved. The values of Vo, R1, R2 and R3 are determined according to the electrical appliance grade of the relay KM.
Input voltage Up of voltage stabilizing circuit unit 1 Wave generation, e.g. Up 1 The output voltage Vo is increased along with the increase, and the controllable precise voltage stabilizing source K changes the current after being regulated, so that the current flows through the current limiting resistor R 1 Is increased by the current of R 1 And therefore the output voltage Vo decreases, realizing a regulated output. When Up 1 The principle of regulation is the same when decreasing.
When the voltage in the secondary side circuit of the transformer is the bus high voltage, the bus potential Up can have certain fluctuation, vo output by the voltage stabilizing circuit unit can be basically stabilized at the optimal working voltage capable of enabling the relay to act, and the reliability of KM working is high. When the primary winding 12 of the transformer is isolated from the secondary winding 13 of the transformer, the bus potential Up is the input voltage of the voltage stabilizing circuit unit, and the output voltage Vo of the voltage stabilizing circuit unit can provide exciting voltage for the exciting coil of the relay KM, so that the two normally-closed contacts S1 and S2 of the relay KM are pulled open, and potential safety hazards are eliminated.
In one embodiment, the present invention provides a switching power supply comprising a voltage protection circuit of the switching power supply of any of the embodiments above.
Fig. 4 is a method schematic diagram of an embodiment of a voltage protection method of a switching power supply according to the present invention, as shown in fig. 4:
in step 401, a relay is provided, a normally closed contact of the relay is arranged in a secondary side circuit of the switching power supply, and an exciting coil of the relay is electrically connected with the secondary side circuit.
In step 402, when the primary winding of the transformer fails to be isolated from the secondary winding of the transformer and the secondary voltage on the secondary circuit is the input voltage of the primary winding of the transformer, the secondary voltage is used to provide the exciting voltage to the exciting coil, and the normally-closed contact is opened to cut off the secondary circuit.
A capacitor is provided in the secondary side circuit in parallel with the transformer secondary side winding, and a normally closed contact is provided between the capacitor and the transformer secondary side winding. The number of normally-closed contacts of the relay is two, the two normally-closed contacts are respectively arranged on a first circuit and a second circuit in the secondary side circuit, and the first circuit and the second circuit are respectively connected with two ends of a secondary side winding of the transformer.
In one embodiment, a voltage stabilizing circuit unit is provided, and the exciting coil is electrically connected with the secondary side circuit through the voltage stabilizing circuit unit, wherein the secondary side voltage is an input voltage of the voltage stabilizing circuit unit, and an output voltage of the voltage stabilizing circuit unit is used for providing exciting voltage for the exciting coil. The voltage stabilizing circuit unit is electrically connected with the secondary side circuit through the current limiting resistor. The voltage stabilizing circuit unit comprises a controllable precise voltage stabilizing source and the like, and the output reference voltage of the controllable precise voltage stabilizing source is used as the reference voltage of the output voltage.
Setting a first voltage dividing proportioning resistor and a second voltage dividing proportioning resistorThe first end of the resistor is connected with the first end of the exciting coil, the cathode of the controllable precise voltage stabilizing source and the current limiting resistor respectively. The second end of the first voltage dividing ratio resistor is connected with the reference electrode of the controllable precise voltage stabilizing source and the first end of the second voltage dividing ratio resistor respectively. The second end of the second voltage dividing proportioning resistor is respectively connected with the anode of the controllable precise voltage stabilizing source and the second end of the exciting coil. Output voltage V o ＝U r *(1+R 2 /R 3 ) Wherein, ur is the reference voltage that controllable accurate steady voltage source output.
In the voltage protection circuit and method of the switching power supply and the switching power supply in the above embodiments, the normally closed contact of the relay is arranged in the secondary side circuit, and the exciting coil is electrically connected with the secondary side circuit; when the transformer winding is in isolation failure and the secondary side voltage is the input voltage of the primary side winding of the transformer, the secondary side voltage is used for providing exciting voltage for the exciting coil, and the normally closed contact is disconnected to cut off the secondary side circuit; when isolation failures such as short circuit and the like occur between the primary side winding and the secondary side winding of the transformer, the relay of the protection circuit cuts off the connection between the secondary side circuit and the rear end load, so that the protection circuit can play a role in protecting personnel safety and the rear end load; the product intellectualization is improved, and the use feeling of a user is improved.
The method and system of the present invention may be implemented in a number of ways. For example, the methods and systems of the present invention may be implemented by software, hardware, firmware, or any combination of software, hardware, firmware. The above-described sequence of steps for the method is for illustration only, and the steps of the method of the present invention are not limited to the sequence specifically described above unless specifically stated otherwise. Furthermore, in some embodiments, the present invention may also be embodied as programs recorded in a recording medium, the programs including machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers a recording medium storing a program for executing the method according to the present invention.
The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
Claims (9)
1. A voltage protection circuit for a switching power supply, comprising:
a relay; the normally closed contact of the relay is arranged in a secondary side circuit of the switching power supply, and the exciting coil of the relay is electrically connected with the secondary side circuit; when the primary side winding of the transformer and the secondary side winding of the transformer are in isolation failure and the secondary side voltage on the secondary side circuit is the input voltage of the primary side winding of the transformer, the secondary side voltage is used for providing exciting voltage for the exciting coil, and the normally closed contact is disconnected to cut off the secondary side circuit;
wherein, a capacitor connected in parallel with the secondary side winding of the transformer is arranged in the secondary side circuit, and the normally closed contact is arranged between the capacitor and the secondary side winding of the transformer; the exciting coil is electrically connected with the secondary side circuit through a voltage stabilizing circuit unit, the voltage stabilizing circuit unit is electrically connected with the secondary side circuit through a current limiting resistor, the secondary side voltage is the input voltage of the voltage stabilizing circuit unit, and the output voltage of the voltage stabilizing circuit unit is used for providing the exciting voltage for the exciting coil; the voltage stabilizing circuit unit includes: and the reference voltage output by the controllable precise voltage stabilizing source is used as the reference voltage of the output voltage.
2. The voltage protection circuit of claim 1, wherein,
the voltage stabilizing circuit unit includes: the first voltage division proportioning resistor and the second voltage division proportioning resistor; the first end of the first voltage dividing ratio resistor is respectively connected with the first end of the exciting coil, the cathode of the controllable precise voltage stabilizing source and the current limiting resistor; the second end of the first voltage dividing ratio resistor is respectively connected with the reference electrode of the controllable precise voltage stabilizing source and the first end of the second voltage dividing ratio resistor; and the second end of the second voltage division proportioning resistor is respectively connected with the anode of the controllable precise voltage stabilizing source and the second end of the exciting coil.
3. The voltage protection circuit of claim 2, wherein,
the output voltage V o ＝U r *(1+R 2 /R 3 ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein Ur is the reference voltage output by the controllable precise voltage stabilizing source, R 2 R is the resistance value of the first partial pressure proportioning resistor 3 And the resistance value of the second voltage division ratio resistor.
4. The voltage protection circuit of claim 1, wherein,
the number of normally closed contacts of the relay is two, the two normally closed contacts are respectively arranged on a first circuit and a second circuit in the secondary side circuit, and the first circuit and the second circuit are respectively connected with two ends of a secondary side winding of the transformer.
5. A switching power supply, comprising:
a voltage protection circuit of a switching power supply as claimed in any one of claims 1 to 4.
6. A voltage protection method for a switching power supply, comprising:
a relay is arranged, a normally closed contact of the relay is arranged in a secondary side circuit of the switching power supply, and an exciting coil of the relay is electrically connected with the secondary side circuit; wherein, a capacitor connected in parallel with the secondary side winding of the transformer is arranged in the secondary side circuit, and the normally closed contact is arranged between the capacitor and the secondary side winding of the transformer;
when the primary side winding of the transformer and the secondary side winding of the transformer are in isolation failure and the secondary side voltage on the secondary side circuit is the input voltage of the primary side winding of the transformer, the secondary side voltage is used for providing exciting voltage for the exciting coil, and the normally closed contact is disconnected to cut off the secondary side circuit;
a voltage stabilizing circuit unit is arranged, and the exciting coil is electrically connected with the secondary side circuit through the voltage stabilizing circuit unit; the secondary side voltage is the input voltage of the voltage stabilizing circuit unit, and the output voltage of the voltage stabilizing circuit unit is used for providing the exciting voltage for the exciting coil; the voltage stabilizing circuit unit includes: a controllable precision voltage stabilizing source; the reference voltage output by the controllable precise voltage stabilizing source is used as the reference voltage of the output voltage;
and the voltage stabilizing circuit unit is electrically connected with the secondary side circuit through the current limiting resistor.
7. The method of claim 6, wherein,
setting a first voltage division proportioning resistor and a second voltage division proportioning resistor; the first end of the first voltage dividing ratio resistor is respectively connected with the first end of the exciting coil, the cathode of the controllable precise voltage stabilizing source and the current limiting resistor; the second end of the first voltage dividing ratio resistor is respectively connected with the reference electrode of the controllable precise voltage stabilizing source and the first end of the second voltage dividing ratio resistor; and the second end of the second voltage division proportioning resistor is respectively connected with the anode of the controllable precise voltage stabilizing source and the second end of the exciting coil.
8. The method of claim 7, wherein,
the output voltage V o ＝U r *(1+R 2 /R 3 )；
Wherein Ur is the reference voltage output by the controllable precise voltage stabilizing source, R 2 R is the resistance value of the first partial pressure proportioning resistor 3 And the resistance value of the second voltage division ratio resistor.
9. The method of claim 6, wherein,
the number of normally-closed contacts of the relay is two, the two normally-closed contacts are respectively arranged on a first circuit and a second circuit in the secondary side circuit, and the first circuit and the second circuit are respectively connected with two ends of a secondary side winding of the transformer.
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| JP2014023300A (en) * | 2012-07-19 | 2014-02-03 | Murata Mach Ltd | Overvoltage protection device |
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| JP2017028818A (en) * | 2015-07-21 | 2017-02-02 | Idec株式会社 | Switching power source |
| CN206517042U (en) * | 2017-03-16 | 2017-09-22 | 国网黑龙江省电力有限公司 | The shock controller of power transformer |
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| JPH09205721A (en) * | 1996-01-24 | 1997-08-05 | Fujitsu Ltd | Circuit breaker for emergency power source disconnection |
| CN201298441Y (en) * | 2008-10-27 | 2009-08-26 | 魏明 | Voltage stabilizing transformer |
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