CN215817922U - Parallel current-sharing circuit, switching power supply, frequency converter and servo system - Google Patents
Parallel current-sharing circuit, switching power supply, frequency converter and servo system Download PDFInfo
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- CN215817922U CN215817922U CN202122035649.5U CN202122035649U CN215817922U CN 215817922 U CN215817922 U CN 215817922U CN 202122035649 U CN202122035649 U CN 202122035649U CN 215817922 U CN215817922 U CN 215817922U
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Abstract
The application relates to a parallel current-sharing circuit, a switching power supply, a frequency converter and a servo system, and belongs to the technical field of switching power supplies. The parallel current-sharing circuit is applied to switch power supplies connected in parallel, the input end of the parallel current-sharing circuit is connected with the positive voltage output end of the switch power supplies, and the parallel current-sharing circuit comprises a current-sharing module and at least two voltage-dividing sub-circuits; the number of the switch power supplies is the same as that of the voltage dividing sub-circuits, and the voltage dividing sub-circuits correspond to the switch power supplies one to one; the voltage division subcircuit comprises a voltage division resistor; the resistance values of the voltage dividing resistors are the same; the current equalizing module comprises a plurality of diodes or common cathode diodes. The voltage difference between each path of the switch power supplies connected in parallel is reduced through the current equalizing module, so that the difference of output current between each path is also reduced, the problems of complex scheme and high cost of the parallel current equalizing circuit are solved, and the effect of better parallel current equalizing of the multi-path switch power supplies is realized with simple circuits and low cost.
Description
Technical Field
The application relates to the technical field of switching power supplies, in particular to a parallel current-sharing circuit, a switching power supply, a frequency converter and a servo system.
Background
In industrial equipment, switching power supplies are widely used, wherein the common output voltage levels are 12VDC, 15VDC, 24VDC, 36VDC and 48VDC, and the switching power supplies outputting the specification above 48VDC are less. However, some industrial applications require a DC voltage of 48VDC to 220 VDC. For an output power supply of 48VDC to 220VDC, due to the limitation of factors such as efficiency, voltage stress of a power device and the like, the power of a single power supply is difficult to be large, and a plurality of power supplies are required to be connected in parallel to realize the required output power.
A plurality of power supplies are connected in parallel, the problem of parallel non-current sharing is solved inevitably, a special parallel current sharing control chip is also arranged on the market, and parallel current sharing is realized by detecting current and controlling the output capacity of each power supply, but the scheme is complex and has higher cost. For the occasions without the requirement of the hard index of the power supply efficiency, the purpose of parallel current sharing can be realized by optimizing the circuit scheme.
SUMMERY OF THE UTILITY MODEL
In order to solve the problems of complex scheme and high cost of the parallel current-sharing circuit, the application provides a parallel current-sharing circuit, a switching power supply, a frequency converter and a servo system.
In a first aspect, the present application provides a parallel current-sharing circuit, which is applied to a switching power supply connected in parallel, wherein an input end of the parallel current-sharing circuit is connected to a positive voltage output end of the switching power supply, and the parallel current-sharing circuit includes a current-sharing module and at least two voltage-dividing sub-circuits;
the number of the switch power supplies is the same as that of the voltage dividing sub-circuits, and the voltage dividing sub-circuits correspond to the switch power supplies one to one; the voltage division subcircuit comprises a voltage division resistor; the resistance values of the voltage dividing resistors are the same;
the current equalizing module comprises a plurality of diodes, the number of the diodes is the same as that of the voltage dividing resistors, and the diodes correspond to the voltage dividing resistors one to one; the anode of the diode is used as the input end of the current-sharing module, and the cathodes of the diodes are connected together and used as the output end of the current-sharing module; the first end of the voltage division resistor is connected with the positive voltage output end of the corresponding switching power supply, and the second end of the voltage division resistor is connected with the anode of the corresponding diode;
or the like, or, alternatively,
the current equalizing module comprises common cathode diodes, the number of anodes of the common cathode diodes is the same as that of the divider resistors, and the anodes of the common cathode diodes correspond to the divider resistors one by one; the anode of the common cathode diode is used as the input end of the current-sharing module, and the common cathode of the common cathode diode is used as the output end of the current-sharing module; the first end of the voltage division resistor is connected with the positive voltage output end of the corresponding switching power supply, and the second end of the voltage division resistor is connected with the anode of the corresponding common cathode diode;
further, the above scheme further includes that the current equalizing module includes a plurality of diodes, including: the model of each diode is the same;
furthermore, the above scheme further includes that the current equalizing module further includes a heat sink, and the heat sink is used for dissipating heat of each diode;
further, the above scheme further includes that the current equalizing module is a common cathode diode, the number of the voltage dividing sub-circuits is two, and the voltage dividing sub-circuit includes: a first voltage dividing resistor and a second voltage dividing resistor;
a first end of the first voltage-dividing resistor is connected with a positive voltage output end of a first switching power supply, and a second end of the first voltage-dividing resistor is connected with a first anode of the common-cathode diode;
the first end of the second voltage-dividing resistor is connected with the positive voltage output end of the second switching power supply, and the second end of the second voltage-dividing resistor is connected with the second anode of the common-cathode diode;
the cathode of the common cathode diode is used as the current-sharing output end of the parallel current-sharing circuit;
further, the scheme also comprises that the divider resistor is a precision resistor.
In a second aspect, the present application provides a switching power supply, including any one of the above parallel current sharing circuits.
In a third aspect, the present application provides a frequency converter comprising the switching power supply described above.
In a fourth aspect, the present application provides a servo system comprising the switching power supply described above.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
the utility model provides a parallelly connected circuit that flow equalizes, be applied to parallel connection's switching power supply, parallelly connected circuit that flow equalizes's input linked switch power supply's malleation output, parallelly connected circuit that flow equalizes includes flow equalizing module and two at least bleeder circuits, bleeder circuit's quantity is the same with switching power supply's quantity, bleeder circuit and switching power supply one-to-one, bleeder circuit includes divider resistance, every divider resistance's resistance is the same, the flow equalizes the module and includes a plurality of diodes or common cathode diode, divider resistance's first end linked switch power supply's malleation output, divider resistance's second end is connected the positive pole of diode or a positive pole of common cathode diode, common cathode diode's common cathode or the negative pole of diode are connected to and are in the same place as the output of flow equalizing module.
The characteristic that the voltage drop of the diode is in direct proportion to the current is utilized to reduce the voltage difference between each path of the switch power supply connected in parallel, so that the difference of output currents between each path is also reduced, the problems of complex scheme and high cost of a parallel current sharing circuit are solved, and the effect of better parallel current sharing of the multi-path switch power supply is realized by a simple circuit and low cost.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the utility model and together with the description, serve to explain the principles of the utility model.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a circuit diagram of a parallel current sharing circuit according to an embodiment of the present disclosure;
FIG. 2 is a voltage-current curve diagram of a diode according to an embodiment of the present disclosure;
fig. 3 is a circuit diagram of a parallel current sharing circuit according to an embodiment of the present disclosure.
The reference numbers are as follows:
101-a switching power supply; 102-a voltage divider sub-circuit; 103-a current-sharing module; r1 — first divider resistance; r2-second voltage dividing resistor; 1011-a first switching power supply; 1012-a second switching power supply; d1-common cathode diode.
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.
According to an aspect of the embodiments of the present application, an embodiment of a parallel current-sharing circuit is provided, which is applied to a switching power supply 101 connected in parallel, as shown in fig. 1, an input end of the parallel current-sharing circuit is connected to a positive voltage output end of the switching power supply 101, and the parallel current-sharing circuit includes a current-sharing module 103 and at least two voltage-sharing sub-circuits 102;
the number of the switching power supplies 101 is the same as that of the voltage dividing sub-circuits 102, the voltage dividing sub-circuits 102 correspond to the switching power supplies 101 one by one, the voltage dividing sub-circuits 102 comprise voltage dividing resistors, and the resistance values of the voltage dividing resistors are the same;
the current-sharing module 103 comprises a plurality of diodes, the number of the diodes is the same as that of the voltage-dividing resistors, the diodes correspond to the voltage-dividing resistors one by one, anodes of the diodes are used as input ends of the current-sharing module 103, cathodes of the diodes are connected together and used as output ends of the current-sharing module 103, first ends of the voltage-dividing resistors are connected with positive-voltage output ends of the corresponding switch power supplies 101, and second ends of the voltage-dividing resistors are connected with anodes of the corresponding diodes;
or the like, or, alternatively,
the current sharing module 103 comprises common cathode diodes D1, the number of anodes of the common cathode diodes D1 is the same as the number of voltage dividing resistors, the anodes of the common cathode diodes D1 correspond to the voltage dividing resistors one to one, the anode of the common cathode diode D1 serves as the input end of the current sharing module 103, the common cathode of the common cathode diode D1 serves as the output end of the current sharing module 103, the first end of each voltage dividing resistor is connected with the positive voltage output end of the corresponding switching power supply 101, and the second end of each voltage dividing resistor is connected with the anode of the corresponding common cathode diode D1.
In this embodiment, a voltage dividing resistor and a diode are connected to the switching power supplies 101 connected in parallel, when the output voltages of the switching power supplies 101 are different, each switching power supply 101 outputs a voltage because each switching power supply 101 is connected to the voltage dividing resistor, and the voltage drop of the diode is proportional to the current passing through the diode, as shown in fig. 2, the abscissa represents the voltage drop of the diode, and the ordinate represents the current passing through the diode, so that the output voltage difference between the switching power supplies 101 can be reduced, and the purpose of current-sharing output can be achieved.
In one embodiment, when multiple diodes are used in the current sharing module 103, the same type of diodes are used. Although the voltage drop of the diodes is proportional to the current in different types of diodes, the voltage drop corresponding to the same current between the diodes may have slight differences, which affects the current sharing effect. The diodes with the same type are used, the same current among the diodes corresponds to the same voltage drop, and the stable current equalizing effect can be realized.
In one embodiment, the current share module 103 further comprises a heat sink for dissipating heat from each diode. Since the current through the diode is not the same as the diode drop curve at different temperatures, as shown in FIG. 2, TJRepresenting the temperature of the diode, the abscissa representing the voltage drop of the diode, the ordinateShowing the current through the diode, the three curves in the figure each show when TJCurves of current through the diode versus diode voltage drop at 25 deg.C, 100 deg.C and 175 deg.C. In order to eliminate the influence caused by temperature factors, a plurality of diodes share one same radiator, the heat dissipation effect is the same, and the diodes work at the same temperature. Under the same working temperature, corresponding voltage drops of different diodes are the same when the diodes pass the same current, so that the parallel current sharing circuit realizes a stable current sharing effect.
In one embodiment, when there are two parallel switching power supplies 101, there are two voltage dividing sub-circuits 102, as shown in fig. 3, the voltage dividing resistors corresponding to the two voltage dividing sub-circuits 102 include a first voltage dividing resistor R1 and a second voltage dividing resistor R2, and the current sharing module 103 includes a common cathode diode D1, and the connection relationship is as follows:
a first end of the first voltage-dividing resistor R1 is connected to the positive voltage output end of the first switching power supply 1011, and a second end of the first voltage-dividing resistor R1 is connected to the first anode of the common cathode diode D1; a first end of the second voltage-dividing resistor R2 is connected to the positive voltage output end of the second switching power supply 1012, and a second end of the second voltage-dividing resistor R2 is connected to the second anode of the common-cathode diode D1; the cathode of the common cathode diode D1 serves as the current-sharing output terminal VO of the parallel current-sharing circuit.
The common terminal COM of the first switching power supply 1011 and the second switching power supply 1012 are connected together, and an external load is connected between the VO and COM terminals.
The working principle is as follows:
for example, at an operating temperature of 100 ℃ of the common cathode diode D1, a current of 0.1A corresponds to a diode drop of 0.55V, a current of 1A corresponds to a diode drop of 0.65V, and a V/I variation curve can be fitted by the following approximate formula:
v-0.111 × I +0.5389, where I is the current flowing through the diode in amperes and V is the diode forward voltage drop in volts.
The circuit equation is as follows:
v1 ═ I1 ═ R1+0.111 ═ I1+0.5389+ VO, V2 ═ I2 ═ R2+0.111 ═ I2+0.5389+ VO, wherein the first voltage dividing resistor R1 and the second voltage dividing resistor R2 select 1 ohm, that is, R1 ═ R2 ═ 1 ohm, and VO is the output voltage of the parallel current sharing circuit.
V1-V2＝(R1+0.111)*(I1-I2)。
Assuming two 220VDC power supplies, total output power is 220V 1.6A 352W, output current: i1+ I2 ═ 1.6A.
If the calibration V1-V2 values deviate at 0.2V, it can be concluded that I1 is 0.89A and I2 is 0.71A.
The current sharing effect is achieved by the simple circuit without adding a current detection and control IC, wherein the current sharing degree is (0.89-0.8)/0.8 is 11%, and the current sharing effect is achieved from the data of the current sharing degree of 11%.
It should be noted that, the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2 are only illustrated as 1 ohm, and may have other resistance values.
In one embodiment, the voltage divider resistor is a precision resistor. The precision resistors are used, so that errors among the voltage dividing resistors in different voltage dividing sub-circuits 102 are reduced, and the voltage dividing and current equalizing effects are better.
In another embodiment provided by the present application, a switching power supply is further provided, which includes any one of the parallel current sharing circuits in the above embodiments. The switch power supply using the parallel current-sharing circuit can keep the current-sharing output of each switch power supply connected in parallel while the output power of the power supply is large, and can simply and conveniently realize the purpose of parallel current sharing in occasions without the requirement of hard indexes of power supply efficiency.
In another embodiment provided by the present application, there is also provided a frequency converter including the switching power supply in the above embodiment.
In another embodiment provided by the present application, there is also provided a servo system including the switching power supply in the above embodiment.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A parallel current-sharing circuit is applied to switch power supplies connected in parallel, the input end of the parallel current-sharing circuit is connected with the positive voltage output end of the switch power supplies, and the parallel current-sharing circuit comprises a current-sharing module and at least two voltage-dividing sub-circuits;
the number of the switch power supplies is the same as that of the voltage dividing sub-circuits, and the voltage dividing sub-circuits correspond to the switch power supplies one to one; the voltage division subcircuit comprises a voltage division resistor; the resistance values of the voltage dividing resistors are the same;
the current equalizing module comprises a plurality of diodes, the number of the diodes is the same as that of the voltage dividing resistors, and the diodes correspond to the voltage dividing resistors one to one; the anode of the diode is used as the input end of the current-sharing module, and the cathodes of the diodes are connected together and used as the output end of the current-sharing module; the first end of the voltage division resistor is connected with the positive voltage output end of the corresponding switching power supply, and the second end of the voltage division resistor is connected with the anode of the corresponding diode;
or the like, or, alternatively,
the current equalizing module comprises common cathode diodes, the number of anodes of the common cathode diodes is the same as that of the divider resistors, and the anodes of the common cathode diodes correspond to the divider resistors one by one; the anode of the common cathode diode is used as the input end of the current-sharing module, and the common cathode of the common cathode diode is used as the output end of the current-sharing module; the first end of the divider resistor is connected with the positive voltage output end of the corresponding switching power supply, and the second end of the divider resistor is connected with the anode of the corresponding common cathode diode.
2. The parallel current sharing circuit of claim 1, wherein the current sharing modules comprise a plurality of diodes, and each of the diodes is of the same type.
3. The parallel current sharing circuit of claim 2, wherein the current sharing module further comprises a heat sink for dissipating heat from each of the diodes.
4. The parallel current sharing circuit of claim 1, wherein the current sharing modules are common cathode diodes, the number of the voltage divider sub-circuits is two, and the voltage divider sub-circuits comprise: a first voltage dividing resistor and a second voltage dividing resistor;
a first end of the first voltage-dividing resistor is connected with a positive voltage output end of a first switching power supply, and a second end of the first voltage-dividing resistor is connected with a first anode of the common-cathode diode;
the first end of the second voltage-dividing resistor is connected with the positive voltage output end of the second switching power supply, and the second end of the second voltage-dividing resistor is connected with the second anode of the common-cathode diode;
and the cathode of the common cathode diode is used as the current-sharing output end of the parallel current-sharing circuit.
5. The parallel current sharing circuit according to any one of claims 1 to 4, wherein the voltage dividing resistor is a precision resistor.
6. A switching power supply, characterized in that it comprises a parallel current sharing circuit according to any one of claims 1 to 5.
7. A frequency converter comprising the switching power supply of claim 6.
8. A servo system comprising the switching power supply of claim 6.
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| CN202122035649.5U CN215817922U (en) | 2021-08-26 | 2021-08-26 | Parallel current-sharing circuit, switching power supply, frequency converter and servo system |
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| CN202122035649.5U CN215817922U (en) | 2021-08-26 | 2021-08-26 | Parallel current-sharing circuit, switching power supply, frequency converter and servo system |
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