CN218733913U - Voltage conversion circuit - Google Patents
Voltage conversion circuit Download PDFInfo
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- CN218733913U CN218733913U CN202222873476.9U CN202222873476U CN218733913U CN 218733913 U CN218733913 U CN 218733913U CN 202222873476 U CN202222873476 U CN 202222873476U CN 218733913 U CN218733913 U CN 218733913U
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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
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- 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 application discloses voltage conversion circuit, voltage conversion circuit includes switch branch road, pulse acquisition branch road, transformer and controller. The primary winding of the transformer is connected with the input power supply and the switch branch, the secondary winding of the transformer is connected with the pulse acquisition branch and the load, and the pulse acquisition branch is connected with the controller. The switch branch circuit is used for being alternately switched on and switched off at a first switching frequency, and the first switching frequency and the output power of the voltage conversion circuit present a positive correlation relationship. The primary winding is charged when the switching branch is switched on, and the secondary winding is discharged based on the electric energy charged by the primary winding when the switching branch is switched off. The pulse acquisition branch circuit is used for acquiring a voltage pulse when the secondary winding discharges every time, and transmitting the voltage pulse to the controller, so that the controller determines whether the load is open-circuited or short-circuited based on the number of the voltage pulses in the first preset time period. By the method, the loss of power can be reduced while whether the load is open or short-circuited is detected.
Description
Technical Field
The present application relates to the field of electronic circuits, and more particularly, to a voltage conversion circuit.
Background
In many electronic products, it is necessary to detect whether a short circuit or an open circuit abnormality occurs in a load in real time to maintain normal and stable operation of the electronic products. For the low-voltage direct-current load passing through the switching power supply, a common detection mode is that at least one resistor connected in series with the low-voltage direct-current load is added to divide voltage, then the MCU acquires current or voltage on the added resistor, and then the MCU can determine whether the low-voltage direct-current load is short-circuited or open-circuited. For example, if the low voltage dc load is open, the MCU may acquire that the current on the increased resistor will decrease to zero.
However, in the above scheme, the increased resistance causes power loss.
SUMMERY OF THE UTILITY MODEL
The present application is directed to a voltage conversion branch capable of reducing power loss while detecting whether a load is open-circuited or short-circuited.
To achieve the above object, in a first aspect, the present application provides a voltage conversion circuit, including:
the device comprises a switching branch, a pulse acquisition branch, a transformer and a controller;
the first end of a primary winding of the transformer is connected with an input power supply, the second end of the primary winding is connected with the first end of the switching branch circuit, the first end of a secondary winding of the transformer is respectively connected with the first end of a pulse acquisition branch circuit and a load, and the second end of the pulse acquisition branch circuit is connected with the controller;
the switching branch circuit is used for being alternately switched on and off at a first switching frequency, wherein the first switching frequency and the output power of the voltage conversion circuit present a positive correlation relationship;
the primary winding is charged when the switching branch is switched on, and the secondary winding is discharged based on the electric energy charged by the primary winding when the switching branch is switched off;
the pulse acquisition branch circuit is used for acquiring a voltage pulse when the secondary winding discharges every time and transmitting the voltage pulse to the controller, so that the controller determines whether the load is open-circuited or short-circuited based on the number of the voltage pulses in a first preset time length.
In an optional manner, the pulse acquisition branch includes a pulse acquisition unit, a current limiting unit, and a filtering unit;
the first end of the pulse acquisition unit is connected with the first end of the secondary winding, the second end of the pulse acquisition unit is connected with the first end of the current limiting unit, and the second end of the current limiting unit is respectively connected with the first end of the filtering unit and the controller;
the pulse acquisition unit is used for conducting when the secondary winding discharges every time so as to output the voltage pulse;
the current limiting unit is used for limiting the current input to the controller;
the filtering unit is used for filtering high-frequency interference signals in the voltage pulse.
In an alternative mode, the pulse acquisition unit includes a first diode;
and the anode of the first diode is connected with the first end of the secondary winding, and the cathode of the first diode is connected with the first end of the current limiting unit.
In an alternative mode, the current limiting unit includes a first resistor;
the first end of the first resistor is connected with the second end of the pulse acquisition unit, and the second end of the first resistor is connected with the first end of the filtering unit.
In an alternative mode, the filtering unit includes a first capacitor;
the first end of the first capacitor is connected with the second end of the current limiting unit and the controller respectively, and the second end of the first capacitor is grounded.
In an optional manner, the filter unit further includes a second resistor;
the second resistor is connected in parallel with the first capacitor.
In an optional manner, the pulse acquisition branch further includes an overvoltage protection unit;
the first end of the overvoltage protection unit, the first end of the filtering unit and the controller are connected to a first node, and the second end of the overvoltage protection unit is connected with the first end of the secondary winding;
the overvoltage protection unit is used for limiting the voltage of the first node to be a first preset voltage when the voltage of the first node is larger than the first preset voltage.
In an alternative mode, the overvoltage protection unit includes a second diode;
and the anode of the second diode is connected to the first node, and the cathode of the second diode is connected with the first end of the secondary winding.
In an optional manner, the voltage conversion circuit further includes a feedback branch, where the switch branch includes a switch chip, and the switch chip includes a drain pin, a source pin, and a feedback pin;
the drain electrode pin is connected with the second end of the primary winding, the feedback pin is connected with the second end of the feedback branch, the first end of the feedback branch is connected with the first end of the secondary winding, and the source electrode pin is grounded;
the feedback branch is used for outputting a corresponding feedback signal to the feedback pin based on the voltage pulse, so that the switch branch determines that the voltage pulse is output.
In an alternative mode, the feedback branch comprises an optical coupler, and the optical coupler comprises a light emitter and a light receiver;
the first end of the illuminator is connected with the first end of the secondary winding, the first end of the light receiver is connected with the feedback pin, and the second end of the illuminator and the second end of the light receiver are both grounded.
The beneficial effect of this application is: the application provides a voltage conversion circuit includes switch branch road, pulse acquisition branch road, transformer and controller. The first end of the primary winding of the transformer is connected with the input power supply, the second end of the primary winding of the transformer is connected with the first end of the switching branch circuit, the first end of the secondary winding of the transformer is respectively connected with the first end of the pulse acquisition branch circuit and the load, and the second end of the pulse acquisition branch circuit is connected with the controller. The switching branch circuit is used for being alternately switched on and switched off at a first switching frequency, wherein the first switching frequency and the output power of the voltage conversion circuit are in positive correlation. The primary winding is charged when the switching branch is switched on, and the secondary winding is discharged based on the electric energy charged by the primary winding when the switching branch is switched off. The pulse acquisition branch circuit is used for acquiring a voltage pulse when the secondary winding discharges every time and transmitting the voltage pulse to the controller, so that the controller determines whether the load is open-circuited or short-circuited based on the number of the voltage pulses in the first preset time. When the controller determines that the number of the voltage pulses in the first preset time period is greater than the first preset number, it may be determined that the number of times of turning on and off the switch branch in the first preset time period is greater, that is, the first switching frequency is greater, and the output power of the corresponding voltage conversion circuit is greater, so that it may be determined that the load has a short circuit phenomenon. When the controller determines that the number of the voltage pulses in the first preset time period is smaller than the second preset number, the controller may determine that the number of times of turning on and off of the switch branch circuit in the first preset time period is small, that is, the first switching frequency is small, and the output power of the corresponding voltage conversion circuit is small, so that the open circuit phenomenon of the load may be determined. By the method, whether the load is open or short-circuited is detected. Also, it is not necessary to increase the resistance as in the related art, so that the loss of power can be reduced.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
Fig. 1 is a schematic structural diagram of a voltage conversion circuit according to an embodiment of the present disclosure;
fig. 2 is a schematic circuit structure diagram of a voltage conversion circuit according to an embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a voltage conversion circuit 100 according to an embodiment of the present disclosure. As shown in fig. 1, the voltage conversion circuit includes a switching branch 10, a pulse acquisition branch 20, a transformer 30 and a controller 40.
A first end of a primary winding L1 of the transformer 30 is connected to the input power source VIN, a second end of the primary winding L1 is connected to a first end of the switching branch 10, a first end of a secondary winding L2 of the transformer 30 is connected to a first end of the pulse acquiring branch 20 and the load 200, respectively, and a second end of the pulse acquiring branch 20 is connected to the controller 40.
Specifically, the switching branch 10 is configured to be alternately turned on and off at a first switching frequency, wherein the first switching frequency is in a positive correlation with the output power of the voltage converting circuit 100. The primary winding L1 is charged when the switching branch 10 is turned on, and the secondary winding L2 is discharged based on the electric energy charged by the primary winding L1 when the switching branch 10 is turned off. The pulse acquiring branch 20 is configured to acquire one voltage pulse each time the secondary winding L2 is discharged, and transmit the voltage pulse to the controller 40, so that the controller 40 determines whether the load is open-circuited or short-circuited based on the number of voltage pulses in the first preset time period.
In practical applications, the output power of the voltage converting circuit 100 is the input power of the load 200. When the load 200 is short-circuited, the current of the load 200 is increased instantaneously, which results in an increase in the input power required by the load 200, i.e., an increase in the output power of the voltage conversion circuit 100; when the load 200 is open-circuited, the current of the load 200 is reduced to zero, which results in a reduction in the required input power of the load 200, i.e., a reduction in the output power of the voltage conversion circuit 100. The output power of the voltage converting circuit 100 is in a positive correlation with the first switching frequency of the switching branch 10, that is, the first switching frequency increases with the increase of the output power of the voltage converting circuit 100, and decreases with the decrease of the output power. By combining the above, when the load 200 is short-circuited, the output power of the voltage converting circuit 100 is increased, and the first switching frequency is increased; when the load 200 is open-circuited, the output power of the voltage conversion circuit 100 is reduced, and the first switching frequency is reduced.
Meanwhile, if the switching branch 10 is turned on and off once, the secondary winding L2 is discharged once correspondingly, and the pulse obtaining branch 20 can obtain a voltage pulse. The first switching frequency determines the number of times the switching branch 10 is turned on and off within the first predetermined time period, thereby determining the number of voltage pulses within the first predetermined time period. In summary, the controller 40 can determine the actual condition of the first switching frequency by acquiring the voltage pulses through the pulse acquiring branch 20 to determine the number of voltage pulses within the first preset time period, so as to further determine whether the load 200 is open-circuited or short-circuited.
Specifically, when the controller 40 determines that the number of voltage pulses in the first preset time period is greater than the first preset number, it may be determined that the number of times of turning on and off of the switching branch 10 in the first preset time period is greater, that is, the first switching frequency is greater, and the output power of the corresponding voltage conversion circuit 100 is greater (and greater than the first preset output power), so as to determine that the short circuit phenomenon occurs in the load 200.
When the controller 40 determines that the number of the voltage pulses in the first preset time period is smaller than the second preset number, it may be determined that the number of times of turning on and off the switch branch 10 in the first preset time period is less, that is, the first switching frequency is lower, and the output power of the corresponding voltage conversion circuit 100 is lower (and is smaller than the second preset output power), so that it may be determined that the load 200 is open-circuited. By the above manner, detection of whether the load 200 is open or short is realized. Also, it is not necessary to increase the resistance as in the related art, so that the loss of power can be reduced.
In this embodiment, the first preset duration, the first preset number, the second preset number, the first preset output frequency, and the second preset output frequency may be set according to an actual application, which is not limited in this embodiment.
For example, in some embodiments, when the load 200 is actually detected, if the input power of the load 200 when short circuit occurs is greater than a and the input power of the load 200 when open circuit occurs is less than B, then a may be used as the first preset output power and B may be used as the second preset output power. Meanwhile, the number of voltage pulses in the first preset period when a is taken as the output power of the voltage conversion circuit 100 (i.e., as the first preset number) is acquired, and the number of voltage pulses in the first preset period when B is taken as the output power of the voltage conversion circuit 100 (i.e., as the second preset number) is acquired. Thus, when the controller 40 detects that the number of voltage pulses within the first preset time period is greater than the first preset number, the controller 40 may determine that the input power of the load 200 at this time is greater than a, and then determine that the load 200 is short-circuited; when the controller 40 detects that the number of voltage pulses in the first preset time period is less than the second preset number, the controller 40 may determine that the input power of the load 200 at this time is less than B, and determine that the load 200 is open-circuited.
Referring to fig. 2, fig. 2 schematically shows a structure of the voltage converting circuit 100.
As shown in fig. 2, in an embodiment, the pulse acquiring branch 20 includes a pulse acquiring unit 21, a current limiting unit 22 and a filtering unit 23.
A first end of the pulse acquiring unit 21 is connected to a first end of the secondary winding L1, a second end of the pulse acquiring unit 21 is connected to a first end of the current limiting unit 22, and a second end of the current limiting unit 22 is connected to a first end of the filtering unit 23 and the controller 40, respectively.
Specifically, the pulse acquisition unit 21 is configured to be turned on every time the secondary winding L1 is discharged to output a voltage pulse. The current limiting unit 22 is used to limit the current input to the controller 40 to prevent the controller 40 from being damaged due to excessive input current. The filter unit 23 is used for filtering out a high frequency interference signal in the voltage pulse to prevent the controller 40 from being damaged by the input high frequency voltage.
One structure of the pulse acquisition unit 21 is also shown in fig. 2. As shown in fig. 2, the pulse acquisition unit 21 includes a first diode D1.
An anode of the first diode D1 is connected to a first end of the secondary winding L2, and a cathode of the first diode D1 is connected to a first end of the current limiting unit 22.
In this embodiment, the first diode D1 is forward-conducted each time the secondary winding L2 outputs a voltage pulse, which can be output through the cathode of the first diode D1.
Fig. 2 also shows a structure of the current limiting unit 22. As shown in fig. 2, the current limiting unit 22 includes a first resistor R1.
A first end of the first resistor R1 is connected to the second end of the pulse acquiring unit 21, and a second end of the first resistor R1 is connected to the first end of the filtering unit 23 and the controller 40.
Fig. 2 also shows a structure of the filter unit 23. As shown in fig. 2, the filter unit 23 includes a first capacitor C1.
A first end of the first capacitor C1 is connected to the second end of the current limiting unit 22 and the controller 40, respectively, and a second end of the first capacitor C1 is grounded to GND.
In this embodiment, when a high-frequency interference signal occurs in the voltage pulse, the high-frequency interference signal can turn on the first capacitor C1 instantaneously. Therefore, the high-frequency interference signal can charge the first capacitor C1 without being input to the controller 40, so as to filter the high-frequency interference signal.
In an embodiment, the filtering unit 23 further includes a second resistor R2.
The second resistor R2 is connected in parallel with the first capacitor C1. The second resistor R2 is used for consuming the electric energy of the first capacitor C1 when the first capacitor C1 is discharged.
In one embodiment, the pulse acquisition branch 20 further comprises an overvoltage protection unit 24. A first end of the overvoltage protection unit 24, a first end of the filter unit 23, and the controller 40 are connected to the first node P1, and a second end of the overvoltage protection unit 24 is connected to a first end of the secondary winding L2.
Specifically, the overvoltage protection unit 24 is configured to limit the voltage of the first node P1 to a first preset voltage when the voltage of the first node P1 is greater than the first preset voltage, so as to prevent the controller 40 from being damaged due to an excessive voltage on the first node P1.
Fig. 2 also shows a configuration of the overvoltage protection unit 24. As shown in fig. 2, the overvoltage protection unit 24 includes a second diode D2.
The anode of the second diode D2 is connected to the first node P1, and the cathode of the second diode D2 is connected to the first end of the secondary winding L2.
Specifically, when the voltage of the first node P1 is greater than the sum of the conduction voltage drop of the second diode D2 and the voltage between the first ends of the secondary windings L2 (i.e., the first preset voltage in this embodiment), the second diode D2 is forward-conducted to limit the voltage of the first node P1 to the sum of the conduction voltage drop of the second diode D2 and the voltage between the first ends of the secondary windings L2. Therefore, voltage limitation of the voltage at the first node P1 is achieved, which is beneficial to reducing the risk of damage to the controller 40 due to overvoltage of the input voltage.
In an embodiment, the voltage conversion branch 100 further comprises a feedback branch 50. The switch branch 10 includes a switch chip U1, and the switch chip U1 includes a drain terminal (i.e., the 7 th terminal and the 8 th terminal of the switch chip U1), a source terminal (i.e., the 6 th terminal of the switch chip U1), and a feedback terminal (i.e., the 5 th terminal of the switch chip U1).
The 7 th pin and the 8 th pin of the switch chip U1 are both connected with the second end of the primary winding, the 5 th pin of the switch chip U1 is connected with the second end of the feedback branch 50, the first end of the feedback branch 50 is connected with one end of the secondary winding L2, and the 6 th pin of the switch chip U1 is grounded GND.
In this embodiment, the feedback branch 50 is configured to output a corresponding feedback signal to the feedback pin of the switch chip U1 based on the voltage pulse, so that the switch branch U1 determines that the voltage pulse is output. Specifically, during the normal operation of the switch chip U1, the switch chip U1 may determine whether the voltage pulse is output through the feedback signal input on the feedback pin. When the feedback signal input on the feedback pin is a low-level signal, the switch chip U1 determines that a voltage pulse is output, and the switch chip U1 is switched on to charge the primary winding L1; when the feedback signal input to the feedback pin is a high-level signal, the switch chip U1 determines that no voltage pulse is output, and the switch chip U1 is turned off, so that the secondary winding L2 is discharged.
In one embodiment, feedback branch 50 includes an optocoupler U2. The optical coupler U2 includes a light emitter and a light receiver.
The first end of the light emitter (namely the 1 st pin of the optical coupler U2) is connected with the first end of the secondary winding L2, the first end of the light receiver (namely the 3 rd pin of the optical coupler U2) is connected with the feedback pin, and the second end of the light emitter (namely the 2 nd pin of the optical coupler U2) and the second end of the light receiver (namely the 4 th pin of the optical coupler U2) are both grounded GND.
Specifically, when the first end of the secondary winding L2 outputs a voltage pulse, the light emitter is turned on forward and emits light. The light receiver receives the light signal of the light emitter and is conducted, namely the 3 rd pin and the 4 th pin of the optical coupler U2 are communicated. The feedback pin of the switch chip U1 is grounded GND, that is, the feedback pin of the switch chip U1 receives a low level signal. When the first end of the secondary winding L2 does not output a voltage pulse, the light emitter is turned off in the opposite direction, and the light receiver is also turned off. The 3 rd pin and the 4 th pin of the optocoupler U2 are disconnected, and a feedback signal received by a feedback pin of the switch chip U1 is recovered to be a high-level signal.
In an embodiment, the voltage conversion circuit 100 further includes a rectifier bridge U3, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth regulator D6, and a seventh regulator D7.
The first input end of the rectifier bridge U3 is connected to the first end of the input power VIN, the second input end of the rectifier bridge U3 is connected to the second end of the input power VIN, the first input end of the rectifier bridge U3 is connected to the first end of the second capacitor C2, the first end of the third resistor R3, the first end of the third capacitor C3, the first end of the tenth resistor R10, the first end of the ninth resistor R9, and the first end of the primary winding L1, the third resistor R3 is connected to the fourth resistor R4 and the fifth resistor R5 in series in sequence, the first end of the third resistor R3 is the non-series connection end of the third resistor R3, the non-series connection end of the fifth resistor R5 is connected to the power input pin of the switch chip U1 (i.e., the 1 st pin of the switch chip U1), the sixth resistor R6 is connected to the seventh resistor R7 in parallel, the source pin of the switch chip U1 is connected to the power input pin of the switch chip U1 through the sixth resistor R6 and the seventh resistor R7 connected in parallel, the second end of the circuit is connected to the ground, the second terminal of the eighth resistor R3, the second terminal of the switch chip U3 is connected to the drain terminal of the tenth resistor R8, the second terminal of the diode R3, and the second terminal of the diode L10, the diode L10 are connected to the cathode of the diode L10.
A first end of the secondary winding L2 is connected to an anode of a fourth diode D4, a cathode of the fourth diode D4 is respectively connected to a cathode of a fifth diode, a first end of a fourth capacitor C4, a first end of a twelfth resistor R12, a first end of a fifth capacitor C5, a first end of a sixth capacitor C6, a first end of a seventh capacitor C7, a first end of a thirteenth resistor R13, and a first end of a fourteenth resistor R14, a second end of the fourth capacitor C4 is connected to a first end of an eleventh resistor R11, a second end of the eleventh resistor R11 is respectively connected to an anode of the fifth diode D5 and an anode of the first diode D1, a second end of the thirteenth resistor R13 is respectively connected to a first end of a fifteenth resistor R15 and a 1 st pin of the optocoupler U2, a second end of the fifteenth resistor R15 is respectively connected to a first end of a sixteenth resistor R16 and a cathode of the sixth voltage regulator D6, a second end of the sixteenth resistor R16 is connected to a first end of the eighth resistor C8, a second end of the eighth resistor C8 is connected to a second end of the fourteenth resistor R14, a control end of the sixth voltage regulator tube D6 and a first end of the seventeenth resistor R17, a pin 3 of the optocoupler U2 is connected to a first end of the ninth capacitor C9, a cathode of the seventh voltage regulator tube D7 and a feedback pin of the switch chip U1, respectively, a second end of the second capacitor C2, a second end of the twelfth resistor R12, a second end of the fifth capacitor C5, a second end of the sixth capacitor C6, a second end of the seventh capacitor C7, a cathode of the sixth voltage regulator tube D6, a second end of the seventeenth resistor R17, a second end of the ninth capacitor C9 and an anode of the seventh voltage regulator tube D7 are all grounded GND.
In this embodiment, the input power VIN is rectified into dc power through the rectifier bridge U3. When the switch chip U1 is conducted, the primary winding L1 is charged by the direct current to store energy; when the switch chip U1 is turned off, the secondary winding L2 releases energy. Therefore, the first end of the secondary winding L2 generates a voltage, and the voltage is output to the load 200 through the fourth diode D4. Meanwhile, the voltage generated at the first end of the secondary winding L2 is also input to the feedback branch 50, so that the feedback branch 50 outputs a corresponding feedback signal to the feedback pin of the switch chip U1, and thus the switch chip U1 can correspondingly adjust the on-off duration according to the received feedback signal, so as to automatically adjust the voltage output at the first end of the secondary winding L2, and further provide a stable voltage for the load 200. In addition, the controller 40 obtains the voltage (i.e. the voltage pulse in the embodiment of the present application) output by the first end of the secondary winding L2 each time the discharge occurs through the pulse obtaining branch 20, and the controller 40 can determine the first switching frequency of the switching chip U1, then determine the output power of the voltage converting circuit 100, and finally determine whether the load 200 is open-circuited or short-circuited. Because the detection of whether the load is open or short-circuited is realized without adopting an additional resistor in the related art, the power loss can be reduced, and abnormal conditions (such as abnormal circuit operation caused by high temperature of the whole circuit comprising the additional resistor) possibly caused by the heating of the added additional resistor can be prevented.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; within the context of the present application, where technical features in the above embodiments or in different embodiments can also be combined, the steps can be implemented in any order and there are many other variations of the different aspects of the present application as described above, which are not provided in detail for the sake of brevity; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.
Claims (10)
1. A voltage conversion circuit, comprising:
the device comprises a switching branch, a pulse acquisition branch, a transformer and a controller;
the first end of a primary winding of the transformer is connected with an input power supply, the second end of the primary winding is connected with the first end of the switching branch circuit, the first end of a secondary winding of the transformer is respectively connected with the first end of a pulse acquisition branch circuit and a load, and the second end of the pulse acquisition branch circuit is connected with the controller;
the switching branch circuit is used for being alternately switched on and switched off at a first switching frequency, wherein the first switching frequency and the output power of the voltage conversion circuit are in a positive correlation relationship;
the primary winding is charged when the switching branch is switched on, and the secondary winding is discharged based on the electric energy charged by the primary winding when the switching branch is switched off;
the pulse acquisition branch circuit is used for acquiring a voltage pulse when the secondary winding discharges every time and transmitting the voltage pulse to the controller, so that the controller determines whether the load is open-circuited or short-circuited based on the number of the voltage pulses in a first preset time length.
2. The voltage conversion circuit of claim 1, wherein the pulse acquisition branch comprises a pulse acquisition unit, a current limiting unit, and a filtering unit;
the first end of the pulse acquisition unit is connected with the first end of the secondary winding, the second end of the pulse acquisition unit is connected with the first end of the current limiting unit, and the second end of the current limiting unit is respectively connected with the first end of the filtering unit and the controller;
the pulse acquisition unit is used for conducting when the secondary winding discharges every time so as to output the voltage pulse;
the current limiting unit is used for limiting the current input to the controller;
the filtering unit is used for filtering high-frequency interference signals in the voltage pulse.
3. The voltage conversion circuit of claim 2, wherein the pulse acquisition unit comprises a first diode;
and the anode of the first diode is connected with the first end of the secondary winding, and the cathode of the first diode is connected with the first end of the current limiting unit.
4. The voltage conversion circuit of claim 2, wherein the current limiting unit comprises a first resistor;
the first end of the first resistor is connected with the second end of the pulse acquisition unit, and the second end of the first resistor is connected with the first end of the filtering unit.
5. The voltage conversion circuit of claim 2, wherein the filtering unit comprises a first capacitor;
the first end of the first capacitor is connected with the second end of the current limiting unit and the controller respectively, and the second end of the first capacitor is grounded.
6. The voltage conversion circuit of claim 5, wherein the filtering unit further comprises a second resistor;
the second resistor is connected in parallel with the first capacitor.
7. The voltage conversion circuit of claim 3, wherein the pulse acquisition branch further comprises an overvoltage protection unit;
the first end of the overvoltage protection unit, the first end of the filtering unit and the controller are connected to a first node, and the second end of the overvoltage protection unit is connected with the first end of the secondary winding;
the overvoltage protection unit is used for limiting the voltage of the first node to be a first preset voltage when the voltage of the first node is larger than the first preset voltage.
8. The voltage conversion circuit of claim 7, wherein the overvoltage protection unit comprises a second diode;
and the anode of the second diode is connected to the first node, and the cathode of the second diode is connected with the first end of the secondary winding.
9. The voltage conversion circuit of claim 1, further comprising a feedback branch, the switch branch comprising a switch chip, the switch chip comprising a drain pin, a source pin, and a feedback pin;
the drain electrode pin is connected with the second end of the primary winding, the feedback pin is connected with the second end of the feedback branch circuit, the first end of the feedback branch circuit is connected with the first end of the secondary winding, and the source electrode pin is grounded;
the feedback branch is used for outputting a corresponding feedback signal to the feedback pin based on the voltage pulse, so that the switch branch determines that the voltage pulse is output.
10. The voltage conversion circuit of claim 9, wherein the feedback branch comprises an optocoupler, the optocoupler comprising a light emitter and a light receiver;
the first end of the light emitter is connected with the first end of the secondary winding, the first end of the light receiver is connected with the feedback pin, and the second end of the light emitter and the second end of the light receiver are both grounded.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222873476.9U CN218733913U (en) | 2022-10-27 | 2022-10-27 | Voltage conversion circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222873476.9U CN218733913U (en) | 2022-10-27 | 2022-10-27 | Voltage conversion circuit |
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| CN218733913U true CN218733913U (en) | 2023-03-24 |
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| CN202222873476.9U Active CN218733913U (en) | 2022-10-27 | 2022-10-27 | Voltage conversion circuit |
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