Current sharing circuit and power supply system

Abstract

The invention discloses a current sharing circuit and a power supply system. The current sharing circuit comprises an output current sampling module, a current mirror and an output feedback module; the output current sampling module is used for collecting the output current of the power supply module; the current mirror is connected with the output end of the output current sampling module and the first input end of the output feedback module. The current mirror is used for mirroring the output current of the output current sampling module according to a set proportion. The second input end of the output feedback module is connected with the output end of the power supply module, the output feedback module is used for amplifying the difference value between the voltage of the first input end and the voltage of the second input end and then feeding back to the voltage feedback end of the power supply module, and the output feedback module is further used for adjusting the output voltage of the power supply module according to the voltage of the first input end; the power module is used for adjusting output voltage according to signals of the voltage feedback end. According to the invention, the precision of the output voltage when the power supply module changes from no load to full load can be improved, and the user experience is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a current sharing circuit and a power supply system. Background Art

[0002] In order to meet the load power and reliability requirements, the power supply system often uses multiple power modules in parallel. During the parallel use, due to the differences between the power modules, the current shared by each power module will be different. In order to ensure the current balance between the multiple power modules in the power supply system, a current balance circuit needs to be set.

[0003] The existing current balancing circuit uses an output impedance method (ie, a droop method) to achieve a current balancing effect. However, as the load changes, the output error of the power supply is large and the accuracy of the output voltage is low. Summary of the invention

[0004] The present invention provides a current balancing circuit and a power supply system to reduce the output error of the power supply and improve the accuracy of the output voltage of the power supply.

[0005] In the first aspect, the present invention provides a current equalization circuit including: an output current sampling module, a current mirror and an output feedback module; the output current sampling module is used to collect the output current of the power supply module; the current mirror is respectively connected to the output end of the output current sampling module and the first input end of the output feedback module, and the current mirror is used to mirror the output current of the output current sampling module according to a set ratio; the second input end of the output feedback module is connected to the output end of the power supply module, the output feedback module is used to amplify the difference between the voltage of the first input end and the voltage of the second input end and then feed it back to the voltage feedback end of the power supply module, and the output feedback module is also used to adjust the output voltage of the power supply module according to the voltage of the first input end; the power supply module is used to adjust the output voltage according to the signal of the voltage feedback end.

[0006] Optionally, the output feedback module includes a voltage divider unit, a resistor unit and a voltage error amplifying unit; the first input end of the voltage error amplifying unit serves as the first input end of the output feedback module, and the output end of the voltage error amplifying unit serves as the output end of the output feedback module; the first end of the voltage divider unit serves as the second input end of the output feedback module, the second end of the voltage divider unit is connected to the second input end of the voltage error amplifying unit, the third end of the voltage divider unit is grounded, and the voltage divider unit is used to feed back the actual output voltage of the power supply module to the second input end of the voltage error amplifying unit; the first end of the resistor unit is connected to the reference voltage, and the second end of the resistor unit is connected to the first input end of the voltage error amplifying unit.

[0007] Optionally, the voltage divider unit includes a first resistor and a second resistor; the first end of the first resistor serves as the first end of the voltage divider unit, the second end of the first resistor is connected to the first end of the second resistor and serves as the second end of the voltage divider unit; the second end of the second resistor serves as the third end of the voltage divider unit.

[0008] Optionally, the resistance unit includes a third resistor, a first end of the third resistor serves as the first end of the resistance unit, and a second end of the third resistor serves as the second end of the resistance unit.

[0009] Optionally, the voltage error amplification unit includes an error amplifier, a fourth resistor, a fifth resistor, a first capacitor and an optocoupler isolator; the non-inverting input terminal of the error amplifier serves as the first input terminal of the voltage error amplification unit, and the inverting input terminal of the error amplifier serves as the second input terminal of the voltage error amplification unit; the first end of the fourth resistor is connected to the inverting input terminal of the error amplifier, the second end of the fourth resistor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the output terminal of the error amplifier; the first end of the fifth resistor is connected to the output terminal of the error amplifier, the first end of the optocoupler isolator is connected to the first power supply voltage, the second end of the optocoupler isolator is connected to the second end of the fifth resistor, the third end of the optocoupler isolator is connected to the second power supply voltage, and the fourth end of the optocoupler isolator serves as the output terminal of the voltage error amplification unit.

[0010] Optionally, the current mirror includes a first transistor, a second transistor, a sixth resistor, a seventh resistor and an eighth resistor; the first end of the sixth resistor is connected to the output end of the output current sampling module, and the second end of the sixth resistor is connected to the collector of the first transistor; the first end of the seventh resistor is connected to the emitter of the first transistor, and the second end of the seventh resistor is grounded; the first end of the eighth resistor is connected to the emitter of the second transistor, and the second end of the eighth resistor is grounded; the base of the second transistor is connected to the base of the first transistor, and the collector of the second transistor is connected to the first input end of the output feedback module.

[0011] Optionally, the output current sampling module includes an output current sampling unit and a current amplifying unit; the output current sampling unit is connected in series with the negative voltage output terminal of the power supply module, and is used to convert the output current of the power supply module into a voltage signal and input it into the current amplifying unit; the first input terminal of the current amplifying unit is connected to the first terminal of the output current sampling unit, and the second input terminal of the current amplifying unit is connected to the second terminal of the output current sampling unit, and the current amplifying unit is used to amplify the voltage signal.

[0012] Optionally, the output current sampling unit includes a sampling resistor, a first end of the sampling resistor serves as a first end of the output current sampling unit, and a second end of the sampling resistor serves as a second end of the output current sampling unit.

[0013] Optionally, the current amplification unit includes an operational amplifier, a ninth resistor, a tenth resistor and an eleventh resistor; the first end of the ninth resistor serves as the first input end of the current amplification unit, and the second end of the ninth resistor is connected to the in-phase input end of the operational amplifier; the first end of the tenth resistor serves as the second input end of the current amplification unit, and the second end of the tenth resistor is connected to the inverting input end of the operational amplifier; the first end of the eleventh resistor is connected to the inverting input end of the operational amplifier, and the second end of the eleventh resistor is connected to the output end of the operational amplifier, and the output end of the operational amplifier serves as the output end of the current amplification unit.

[0014] Optionally, the current amplifying unit further includes a twelfth resistor, a first end of the twelfth resistor is connected to a third power supply voltage, and a second end of the twelfth resistor is connected to a non-inverting input end of the operational amplifier.

[0015] In a second aspect, an embodiment of the present invention further provides a power supply system, comprising at least two current balancing circuits provided by any embodiment of the present invention, and at least two power supply modules connected in parallel, wherein the current balancing circuits are connected to the power supply modules in a one-to-one correspondence.

[0016] The current balancing circuit of the embodiment of the present invention includes an output current sampling module, a current mirror and an output feedback module. The output current of the power module is collected by the output current sampling module, and the output current of the power module is mirrored by the current mirror according to a set ratio to control the voltage of the first input terminal of the output feedback module. Since the setting ratio of the current mirror is adjustable, the current mirror can convert the output current of the output current sampling module into current control of different sizes. For example, the current mirror can convert the output current of the output current sampling module into micro-ampere level current control. The voltage of the first input terminal of the output feedback module can be adjusted by adjusting the size of the current mirror output current. Since the output voltage of the power module is positively correlated with the voltage of the first input terminal of the output feedback module, the output voltage of the power module can be controlled by adjusting the size of the current mirror output current. By controlling the size of the output voltage of the power module, the output error of the power module can be reduced and the accuracy of the output voltage of the power module can be improved. For example, the accuracy of the output voltage of the power module can be improved when the power module changes from no-load to load.

[0017] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 is a structural schematic diagram of a current balancing circuit provided by an embodiment of the present invention;

[0020] Figure 2 It is a waveform diagram of the output voltage and output current of the power module with the current balancing circuit provided by the embodiment of the present invention when the power module changes from no-load to full-load;

[0021] Figure 3 is a structural schematic diagram of another current balancing circuit provided by an embodiment of the present invention;

[0022] Figure 4 is a structural schematic diagram of another current balancing circuit provided by an embodiment of the present invention;

[0023] Figure 5 is a structural schematic diagram of another current balancing circuit provided by an embodiment of the present invention;

[0024] Figure 6 is a structural schematic diagram of another current balancing circuit provided by an embodiment of the present invention;

[0025] Figure 7 is a structural schematic diagram of another current balancing circuit provided by an embodiment of the present invention;

[0026] Figure 8 is a simulation waveform diagram of a voltage Imean provided by an embodiment of the present invention;

[0027] Fig. 9 is a simulation waveform diagram of a voltage V1 provided in an embodiment of the present invention;

[0028] Fig.10 It is a structural schematic diagram of a power supply system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0031] Figure 1 Schematic diagram of a current balancing circuit provided by an embodiment of the present invention. Figure 1 As shown, the current balancing circuit 10 includes: an output current sampling module 11, a current mirror 12 and an output feedback module 13. The output current sampling module 11 is used to collect the output current of the power module 10.

[0032] The current mirror 12 is connected to the output end of the output current sampling module 111 and the first input end of the output feedback module 13 respectively. The current mirror 12 is used to mirror the output current of the output current sampling module 11 according to a set ratio.

[0033] The second input terminal of the output feedback module 13 is connected to the output terminal of the power module 20. The output feedback module 13 is used to amplify the difference between the voltage at the first input terminal and the voltage at the second input terminal and then feed it back to the voltage feedback terminal of the power module 20. The output feedback module 13 is also used to adjust the output voltage of the power module 20 according to the voltage at the first input terminal.

[0034] The power module 20 is used to adjust the output voltage according to the signal of the voltage feedback terminal FB.

[0035] Specifically, the output current sampling module 11 is connected to the negative voltage output terminal Vout- of the power module 20. The output current sampling module 11 can be any module with a current sampling function. For example, the output current sampling module 11 can be a module including at least a sampling resistor, or a chip including at least a Hall current sensor, so as to sample the output current of the power module 20. In some embodiments, the output current sampling module 11 can also include an operational amplifier to amplify the collected output current of the power module 10.

[0036] The embodiment of the present invention does not specifically limit the specific structure of the current mirror 12. Optionally, the current mirror 12 can be a basic current mirror, a cascode current mirror, a Wilson current mirror, or a mirror ratio current source. The set ratio of the output current IC1 of the current mirror 12 to the input current IR can be adjusted by adjusting the resistance value of the resistor and / or the width-to-length ratio of the transistor in the current mirror 12. In some embodiments, the current mirror 12 converts the output current of the output current sampling module 11 into microampere level current control according to the set ratio.

[0037] The second input terminal of the output feedback module 13 is connected to the positive voltage output terminal Vout+ of the power module 20. The output feedback module 13 may be a module including at least an error amplifier. The output voltage of the power module 20 is positively correlated with the voltage of the first input terminal of the output feedback module 13. In other words, the greater the voltage of the first input terminal of the output feedback module 13, the greater the output voltage of the power module 20, and the smaller the voltage of the first input terminal of the output feedback module 13, the smaller the output voltage of the power module 20. For example, the output voltage of the power module 20 is in a positive proportional relationship with the voltage of the first input terminal of the output feedback module 13.

[0038] by Figure 1 Taking the circuit structure shown in the figure as an example, the specific working principle of the current balancing circuit provided in this embodiment is as follows:

[0039] When multiple power modules 20 are used in parallel, it is often the case that one power module has a high output current and the other has a low output current. At this time, if the output voltage of the power module with a high output current can be reduced, and / or the output voltage of the power module with a low output current can be increased, parallel current sharing of each power module can be achieved.

[0040] Assuming that the output current of the power module 20 increases, that is, the output current of the output current sampling module 11 increases, the output current is mirrored by the current mirror 12 and superimposed on the first input terminal of the output feedback module 13, so that the voltage of the first input terminal of the output feedback module 13 decreases. Since the output voltage of the power module 20 is positively correlated with the voltage of the first input terminal of the output feedback module 13, the output voltage of the power module 20 decreases, so that the output current of the power module 20 decreases.

[0041] Assuming that the output current of the power module 20 decreases, that is, the output current of the output current sampling module 11 decreases, the output current is mirrored by the current mirror 12 and superimposed on the first input terminal of the output feedback module 13, so that the voltage of the first input terminal of the output feedback module 13 increases. Since the output voltage of the power module 20 is positively correlated with the voltage of the first input terminal of the output feedback module 13, the output voltage of the power module 20 increases, so that the output current of the power module 20 increases.

[0042] Therefore, when the first power module and the second power module are used in parallel, it is assumed that the output current of the first power module is large and the output current of the second power module is small. The output current of the first power module reduces the output voltage of the first power module through the current balancing circuit 10, and the output current of the first power module decreases at this time. The output current of the second power module increases the output voltage of the second power module through the current balancing circuit 10, and the output current of the second power module increases at this time, and finally the parallel current balancing of the two power modules is realized. In other words, each power module adjusts its own output current, so that the parallel current balancing of each power module can be realized.

[0043] In addition, the output feedback module 13 compares the current voltage of the first input terminal with the voltage of the second input terminal to obtain a difference signal, and inputs the difference signal to the voltage feedback terminal FB of the power module. The power module 20 adjusts the output voltage according to the difference signal of the voltage feedback terminal FB.

[0044] At the same time, since the setting ratio of the current mirror 12 is adjustable, the current mirror 12 can convert the output current of the output current sampling module 11 (i.e., the input current of the current mirror) into current control of different magnitudes, that is, the magnitude of the output current of the current mirror 12 is adjustable, for example, the current mirror 12 can convert the output current of the output current sampling module 11 into microampere-level current control. By adjusting the magnitude of the output current of the current mirror 12, the voltage of the first input terminal of the output feedback module 13 can be adjusted. Since the output voltage of the power supply module 20 is positively correlated with the voltage of the first input terminal of the output feedback module 13, the magnitude of the output voltage of the power supply module 20 can be controlled by adjusting the magnitude of the output current of the current mirror 12. By controlling the magnitude of the output voltage of the power supply module 20, the output error of the power supply module can be reduced, and the accuracy of the output voltage of the power supply module 20 can be improved.

[0045] Figure 2 1 is a waveform diagram of the output voltage and output current of a power module with a current balancing circuit provided by an embodiment of the present invention when the power module changes from no-load to full-load. Figure 2As shown, when the power module 20 is unloaded, the output current Io of the power module is 0A, and the output voltage Vo of the power module is 24V; when the power module 20 is fully loaded, the output current Io of the power module is 20A, and the output voltage Vo of the power module is 23.57V. The accuracy of the output voltage when the power module changes from no-load to full-load is equal to (24-23.57 / 24)×100%=1.8%, that is, the current balancing circuit of the embodiment of the present invention can control the accuracy of the output voltage when the power module changes from no-load to full-load to within ±2%. In the prior art, the accuracy of the output voltage when the power module changes from no-load to full-load is generally around ±4%. In summary, the embodiment of the present invention reduces the error of the output voltage when the power module changes from no-load to full-load, and reduces the error of the output voltage from ±4% to within ±2%, that is, the accuracy of the output voltage when the power module changes from no-load to full-load is improved.

[0046] The current balancing circuit of the embodiment of the present invention includes an output current sampling module, a current mirror and an output feedback module. The output current of the power module is collected by the output current sampling module, and the output current of the power module is mirrored by the current mirror according to a set ratio to control the voltage of the first input terminal of the output feedback module. Since the setting ratio of the current mirror is adjustable, the current mirror can convert the output current of the output current sampling module into current control of different sizes. For example, the current mirror can convert the output current of the output current sampling module into micro-ampere level current control. The voltage of the first input terminal of the output feedback module can be adjusted by adjusting the size of the current mirror output current. Since the output voltage of the power module is positively correlated with the voltage of the first input terminal of the output feedback module, the size of the output voltage of the power module can be controlled by adjusting the size of the current mirror output current. By controlling the size of the output voltage of the power module, the output error of the power module can be reduced and the accuracy of the output voltage of the power module can be improved. For example, the accuracy of the output voltage of the power module is improved when the power module changes from no-load to full-load.

[0047] Figure 3 FIG. 1 is a schematic diagram of another current balancing circuit provided by an embodiment of the present invention. Figure 3 As shown, optionally, the output feedback module 13 includes a voltage dividing unit 131 , a resistance unit 132 and a voltage error amplifying unit 133 .

[0048] The first input terminal of the voltage error amplifying unit 133 serves as the first input terminal of the output feedback module 13 , and the output terminal of the voltage error amplifying unit 133 serves as the output terminal of the output feedback module 13 .

[0049] The first end of the voltage divider unit 131 serves as the second input end of the output feedback module 13, the second end of the voltage divider unit 131 is connected to the second input end of the voltage error amplification unit 133, the third end of the voltage divider unit 131 is grounded, and the voltage divider unit 131 is used to feed back the actual output voltage of the power module 20 to the second input end of the voltage error amplification unit 133.

[0050] A first end of the resistance unit 132 is connected to the reference voltage VREF, and a second end of the resistance unit 132 is connected to a first input end of the voltage error amplifying unit 133 .

[0051] Specifically, the output current IC1 of the current mirror is nIR, and the direction of the output current IC1 of the current mirror is negative, wherein the direction of the current flowing into the current mirror is negative, and the direction of the current flowing out of the current mirror is positive. n represents the set ratio, and IR represents the input current of the current mirror. The voltage V1 of the first input terminal of the voltage error amplifier unit 133 is VREF-IC1×r. Among them, VREF represents the reference voltage, IC1 represents the output current of the current mirror, and r represents the resistance value of the resistance unit 132.

[0052] According to the virtual short circuit theory of the error amplifier, in an ideal case, the voltage V1 of the first input terminal of the voltage error amplifier unit 133 is equal to the voltage V2 of the second input terminal. Since V2=kVo, V1=kVo, that is, Vo=V1 / k, where k represents the voltage division ratio of the resistor between the second terminal and the third terminal of the voltage divider unit 131, and Vo represents the output voltage of the power module.

[0053] by Figure 3 Taking the circuit structure shown in the figure as an example, the specific working principle of the current balancing circuit provided in this embodiment is as follows:

[0054] Assume that the output current of the power module 20 increases, that is, the output current of the output current sampling module 11 increases, that is, the input current IR of the current mirror 12 increases. When the input current IR of the current mirror 12 increases, since the output current IC1 of the current mirror is nIR, the output current IC1 of the current mirror increases. Since the voltage V1 of the first input terminal of the voltage error amplifier unit 133 is VREF-IC1×r, the reference voltage VREF and the resistance value of the resistor unit 132 are both fixed values, when the output current IC1 of the current mirror increases, the voltage V1 of the first input terminal of the voltage error amplifier unit 133 decreases. Since the output voltage Vo of the power module 20 is positively correlated with the voltage V1 of the first input terminal of the voltage error amplifier unit 133, the output voltage of the power module 20 decreases, and the output current of the power module 20 decreases.

[0055] Assume that the output current of the power module 20 decreases, that is, the output current of the output current sampling module 11 decreases, that is, the input current IR of the current mirror 12 decreases. When the input current IR of the current mirror 12 decreases, since the output current IC1 of the current mirror is nIR, the output current IC1 of the current mirror decreases. Since the voltage V1 of the first input terminal of the voltage error amplifier unit 133 is VREF-IC1×r, the reference voltage VREF and the resistance value of the resistor unit 132 are both fixed values, when the output current IC1 of the current mirror decreases, the voltage V1 of the first input terminal of the voltage error amplifier unit 133 increases. Since the output voltage Vo of the power module 20 is positively correlated with the voltage V1 of the first input terminal of the voltage error amplifier unit 133, the output voltage of the power module 20 increases, and the output current of the power module 20 increases.

[0056] In the embodiment of the present invention, by adjusting the size of the set ratio n, the size of the output current IC1 of the current mirror can be adjusted, thereby adjusting the size of the output voltage Vo of the power module 20.

[0057] In addition, the voltage error amplifier 133 compares the current voltage V1 of the first input terminal with the voltage V2 of the second input terminal to obtain a difference signal, and inputs the difference signal to the voltage feedback terminal FB of the power module. The power module 20 adjusts the output voltage according to the difference signal of the voltage feedback terminal FB.

[0058] The embodiment of the present invention does not limit the specific structures of the voltage divider unit 131, the resistor unit 132 and the voltage error amplification unit 133, as long as they have corresponding functions. As a preferred implementation provided by the embodiment of the present invention, Figure 4 is a schematic diagram of the structure of another current balancing circuit provided by an embodiment of the present invention. Figure 4 As shown, optionally, the voltage dividing unit 131 includes a first resistor R1 and a second resistor R2.

[0059] The first end of the first resistor R1 serves as the first end of the voltage divider 131, and the second end of the first resistor R1 is connected to the first end of the second resistor R2 and serves as the second end of the voltage divider 131. The second end of the second resistor R2 serves as the third end of the voltage divider 131.

[0060] Specifically, the voltage V2 at the second input terminal of the voltage error amplifying unit 133 is (r2 / (r1+r2))×Vo, that is, V1=V2=(r2 / (r1+r2))×Vo, so Vo=(1+r1 / r2)V1, wherein r1 represents the resistance value of the first resistor R1, and r2 represents the resistance value of the second resistor R2.

[0061] Optionally, continue to refer to Figure 4The resistance unit 132 includes a third resistor R3, a first end of the third resistor R3 serves as a first end of the resistance unit 132, and a second end of the third resistor R3 serves as a second end of the resistance unit 132. The third resistor R3 converts the output current IC1 of the current mirror 12 into a voltage.

[0062] Optionally, continue to refer to Figure 4 The voltage error amplifying unit 133 includes an error amplifier U1 , a fourth resistor R4 , a fifth resistor R5 , a first capacitor C1 and an optocoupler isolator U2 .

[0063] The non-inverting input terminal of the error amplifier U1 serves as the first input terminal of the voltage error amplifying unit 133 , and the inverting input terminal of the error amplifier U1 serves as the second input terminal of the voltage error amplifying unit 133 .

[0064] The first end of the fourth resistor R4 is connected to the inverting input terminal of the error amplifier U1, the second end of the fourth resistor R4 is connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is connected to the output terminal of the error amplifier U1. The first end of the fifth resistor R5 is connected to the output terminal of the error amplifier U1.

[0065] The first end of the optocoupler isolator U2 is connected to the first power supply voltage VCC1, the second end of the optocoupler isolator U2 is connected to the second end of the fifth resistor R5, the third end of the optocoupler isolator VCC1 is connected to the second power supply voltage VCC2, and the fourth end of the optocoupler isolator serves as the output end of the voltage error amplification unit 133.

[0066] Specifically, the fourth resistor R4 and the first capacitor C1 form a negative feedback circuit for the stability of the output signal of the error amplifier U1. The fifth resistor R5 is a current limiting resistor. The embodiment of the present invention isolates the error amplifier U1 from the power module 20 through the optical coupler isolator U2, which can improve the stability of the difference signal output by the error amplifier U1, thereby improving the anti-interference ability of the over-current balancing circuit 10.

[0067] by Figure 4 Taking the circuit structure shown in the figure as an example, the specific working principle of the current balancing circuit provided in this embodiment is as follows:

[0068] Assume that the output current of the power module 20 increases, that is, the output current of the output current sampling module 11 increases, that is, the input current IR of the current mirror 12 increases. When the input current IR of the current mirror 12 increases, since the output current IC1 of the current mirror is nIR, the output current IC1 of the current mirror increases. Since the voltage V1 of the non-inverting input terminal of the error amplifier U1 is VREF-IC1×r3, the reference voltage VREF and the resistance value r3 of the third resistor R3 are both fixed values, when the output current IC1 of the current mirror increases, the voltage V1 of the non-inverting input terminal of the error amplifier U1 decreases. Since the output voltage Vo of the power module 20 is (1+r1 / r2)V1, when the voltage V1 of the non-inverting input terminal of the error amplifier U1 decreases, the output voltage Vo of the power module 20 decreases, so that the output current Io of the power module 20 decreases.

[0069] Assume that the output current of the power module 20 decreases, that is, the output current of the output current sampling module 11 decreases, that is, the input current IR of the current mirror 12 decreases. When the input current IR of the current mirror 12 decreases, since the output current IC1 of the current mirror is nIR, the output current IC1 of the current mirror decreases. Since the voltage V1 of the non-inverting input terminal of the error amplifier U1 is VREF-IC1×r3, the reference voltage VREF and the resistance value r3 of the third resistor R3 are both fixed values, when the output current IC1 of the current mirror decreases, the voltage V1 of the non-inverting input terminal of the error amplifier U1 increases. Since the output voltage Vo of the power module 20 is (1+r1 / r2)V1, when the voltage V1 of the non-inverting input terminal of the error amplifier U1 increases, the output voltage Vo of the power module 20 increases, so that the output current Io of the power module 20 increases.

[0070] In addition, the error amplifier U1 compares the current voltage V1 at the non-inverting input terminal with the voltage V2 at the inverting input terminal to obtain a difference signal, and inputs the difference signal to the voltage feedback terminal FB of the power module through the optical coupler isolator U2. The power module 20 adjusts the output voltage according to the difference signal at the voltage feedback terminal FB.

[0071] Figure 5 is a schematic diagram of the structure of another current balancing circuit provided by an embodiment of the present invention. Figure 5 As shown, optionally, the current mirror 12 includes a first transistor Q1, a second transistor Q2, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8.

[0072] The first end of the sixth resistor R6 is connected to the output end of the output current sampling module 11, and the second end of the sixth resistor R6 is connected to the collector of the first transistor Q1. The first end of the seventh resistor R7 is connected to the emitter of the first transistor Q1, and the second end of the seventh resistor R7 is grounded. The first end of the eighth resistor R8 is connected to the emitter of the second transistor Q2, and the second end of the eighth resistor R8 is grounded. The base of the second transistor Q2 is connected to the base of the first transistor Q1, and the collector of the second transistor Q2 is connected to the first input end of the output feedback module 13.

[0073] Specifically, the output current IC1 of the current mirror is (r7 / r8)*IR. The proportional relationship between IC1 and IR can be changed by simply changing the values ​​of r7 and r8. In the formula, the input current IR of the current mirror is (Imean-Vbe1) / (r6+r7).

[0074] That is to say

[0075] Wherein r6 is the resistance value of the sixth resistor R6, r7 is the resistance value of the seventh resistor R7, r8 is the resistance value of the eighth resistor R8, Imean is the voltage at the output end of the output current sampling module 12, and Vbe1 is the voltage difference between the base and the emitter of the first transistor Q1.

[0076] Figure 6 is a schematic diagram of the structure of another current balancing circuit provided by an embodiment of the present invention. Figure 6 As shown, optionally, the output current sampling module 11 includes an output current sampling unit 111 and a current amplifying unit 112 .

[0077] The output current sampling unit 111 is connected in series with the negative voltage output terminal Vout− of the power module 20 , and is used to convert the output current of the power module 20 into a voltage signal and input it into the current amplifying unit 112 .

[0078] A first input terminal of the current amplifying unit 112 is connected to a first terminal of the output current sampling unit 111 , and a second input terminal of the current amplifying unit 112 is connected to a second terminal of the output current sampling unit 111 . The current amplifying unit 112 is used to amplify the voltage signal.

[0079] Optionally, continue to refer to Figure 6 The output current sampling unit includes a sampling resistor Rsense, a first end of the sampling resistor Rsense serves as a first end of the output current sampling unit 111 , and a second end of the sampling resistor Rsense serves as a second end of the output current sampling unit 111 .

[0080] Optionally, continue to refer to Figure 6The current amplifying unit includes an operational amplifier U3, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11.

[0081] A first end of the ninth resistor R9 serves as a first input end of the current amplifying unit 112 , and a second end of the ninth resistor is connected to a non-inverting input end of the operational amplifier U3 .

[0082] A first end of the tenth resistor R10 serves as a second input end of the current amplifying unit 112 , and a second end of the tenth resistor R10 is connected to an inverting input end of the operational amplifier U3 .

[0083] A first end of the eleventh resistor R11 is connected to the inverting input end of the operational amplifier U3 , a second end of the eleventh resistor R11 is connected to the output end of the operational amplifier U3 , and the output end of the operational amplifier U3 serves as the output end of the current amplifying unit 112 .

[0084] Specifically, the operational amplifier U3 may include a single-side differential pair folded operational amplifier or a complete folded operational amplifier. The ninth resistor R9 and the tenth resistor R10 are current limiting resistors, and the eleventh resistor R11 is a feedback resistor.

[0085] Optionally, continue to refer to Figure 6 The current amplifying unit further includes a twelfth resistor R12, a first end of the twelfth resistor R12 is connected to the third power supply voltage VCC3, and a second end of the twelfth resistor R12 is connected to the non-inverting input end of the operational amplifier U3.

[0086] Specifically, in order to enable the power module 20 to achieve linear current sharing in the full load range, a bias voltage, i.e., a third power supply voltage VCC3, needs to be added to the output current sampling module 11 to ensure that when the power module is unloaded, the voltage Imean at the output end of the output current sampling module 12 is greater than the forward conduction voltage of the transistor in the current mirror 12. The embodiment of the present invention does not specifically limit the magnitude of the third power supply voltage VCC3. Exemplarily, the magnitude of the third power supply voltage VCC3 can be 0.6V.

[0087] Figure 7 is a schematic diagram of the structure of another current balancing circuit provided by an embodiment of the present invention. Figure 7 As shown, the current balancing circuit 10 includes: an output current sampling module 11 , a current mirror 12 and an output feedback module 13 .

[0088] Optionally, the output feedback module 13 includes a voltage divider unit 131, a resistor unit 132 and a voltage error amplification unit 133. Optionally, the voltage divider unit 131 includes a first resistor R1 and a second resistor R2. The resistor unit 132 includes a third resistor R3. The voltage error amplification unit 133 includes an error amplifier U1, a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and an optocoupler isolator U2.

[0089] Optionally, the current mirror 12 includes a first transistor Q1, a second transistor Q2, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8.

[0090] Optionally, the output current sampling module 11 includes an output current sampling unit 111 and a current amplification unit 112. The output current sampling unit includes a sampling resistor Rsense. The current amplification unit 112 includes an operational amplifier U3, a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11.

[0091] Since Therefore, when r6 = 1K, r7 = 1K, r8 = 50k, Vbe1 = 0.6V, and the power supply module is fully loaded, the voltage Imean at the output terminal of the operational amplifier is 3V, and at this time IC1 = 96UA. That is, the current mirror 12 converts the output current signal of the output current sampling module 11 into a microampere current control.

[0092] At this time, the calculation formula for the voltage V1 at the non-inverting input terminal of the error amplifier U1 is as follows:

[0093]

[0094] It can be seen from the above formula that when Imean < Vbe1, the voltage V1 at the non-inverting input terminal of the error amplifier U1 is clamped to be equal to VREF by the reference voltage, and when Imean > Vbe1, the voltage V1 at the non-inverting input terminal of the error amplifier U1 will decrease as the voltage Imean at the output terminal of the operational amplifier U3 increases.

[0095] Imean = A * Io * rsense + I_offset; where A is the proportionality coefficient, Io is the output current of the power supply module, rsense is the resistance value of the sampling resistor, and I_offset is the current bias.

[0096] When A = 80, rsense = 1.5 milliohms, I_offset = 0.6V, VREF = 2.5V, Vbe1 = 0.6V, r6 = 1K, r7 = 1K, r8 = 50K, r3 = 1K, it can be calculated that V1 = 2.5 - (80 * Io * 0.0015 + 0.6 - 0.6) / (1K + 1K) * 1K / 50K * 1K = 2.5 - 0.0024 * Io.

[0097] When a single power module 20 is working, when Io=20A, V1=2.452V, that is, when the power module is working at full load, the output voltage of the power module Vo=24*2.452 / 2.5=23.5392V. The accuracy of the output voltage when the power module changes from no load to full load is equal to (24-23.5392 / 24)×100%=1.9%, that is, the embodiment of the present invention can control the accuracy of the output voltage when the power module changes from no load to full load within ±2%.

[0098] Figure 8 It is a simulation waveform diagram of a voltage Imean provided by an embodiment of the present invention. Fig. 9 : is a simulation waveform diagram of a voltage V1 provided by an embodiment of the present invention. Figure 8 The ordinate represents the voltage Imean at the output of the operational amplifier U3, in V, and the abscissa represents time, in s. Fig. 9 The ordinate represents the voltage V1 at the output of the error amplifier U1, in V, and the abscissa represents time, in s. Figure 8 and Fig. 9 It can be seen that the voltage Imean at the output end of the operational amplifier U3 increases linearly with the increase of the output current of the power module, and the voltage V1 at the non-inverting input end of the error amplifier U1 decreases linearly with the increase of the output current of the power module. In other words, the power module 20 can achieve linear current sharing in the full load range, thereby improving the current sharing accuracy.

[0099] Based on the same inventive concept, the present invention also provides a power supply system. Fig.10 Schematic diagram of a power supply system provided by an embodiment of the present invention. Fig.10 As shown, the power supply system 1 includes at least two current balancing circuits 10 provided in any of the above embodiments, and also includes at least two parallel power modules 20, and the current balancing circuits 10 are connected one-to-one with the power modules 20. The power supply system has the same functional modules and beneficial effects as the current balancing circuit, and the similarities are not repeated here.

[0100] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A current sharing circuit, characterized in that: include: Output current sampling module, current mirror and output feedback module; The output current sampling module is used to collect the output current of the power module; The current mirror is connected to the output end of the output current sampling module and the first input end of the output feedback module respectively, and the current mirror is used to mirror the output current of the output current sampling module according to a set ratio; The second input terminal of the output feedback module is connected to the output terminal of the power module, and the output feedback module is used to amplify the difference between the voltage of the first input terminal and the voltage of the second input terminal and then feed it back to the voltage feedback terminal of the power module, and the output feedback module is also used to adjust the output voltage of the power module according to the voltage of the first input terminal; The power supply module is used to adjust the output voltage according to the signal at the voltage feedback terminal.

2. The current balancing circuit according to claim 1, characterized in that: The output feedback module includes a voltage dividing unit, a resistance unit and a voltage error amplifying unit; The first input end of the voltage error amplifying unit serves as the first input end of the output feedback module, and the output end of the voltage error amplifying unit serves as the output end of the output feedback module; The first end of the voltage divider unit serves as the second input end of the output feedback module, the second end of the voltage divider unit is connected to the second input end of the voltage error amplifying unit, the third end of the voltage divider unit is grounded, and the voltage divider unit is used to feed back the actual output voltage of the power module to the second input end of the voltage error amplifying unit; The first end of the resistance unit is connected to a reference voltage, and the second end of the resistance unit is connected to the first input end of the voltage error amplifying unit.

3. The current balancing circuit according to claim 2, characterized in that: The voltage dividing unit includes a first resistor and a second resistor; The first end of the first resistor serves as the first end of the voltage dividing unit, and the second end of the first resistor is connected to the first end of the second resistor and serves as the second end of the voltage dividing unit; The second end of the second resistor serves as the third end of the voltage dividing unit.

4. The current balancing circuit according to claim 2, characterized in that: The resistance unit includes a third resistor, a first end of the third resistor serves as a first end of the resistance unit, and a second end of the third resistor serves as a second end of the resistance unit.

5. The current balancing circuit according to claim 2, characterized in that: The voltage error amplification unit includes an error amplifier, a fourth resistor, a fifth resistor, a first capacitor and an optocoupler isolator; The non-inverting input terminal of the error amplifier serves as the first input terminal of the voltage error amplifying unit, and the inverting input terminal of the error amplifier serves as the second input terminal of the voltage error amplifying unit; A first end of the fourth resistor is connected to the inverting input end of the error amplifier, a second end of the fourth resistor is connected to the first end of the first capacitor, and a second end of the first capacitor is connected to the output end of the error amplifier; The first end of the fifth resistor is connected to the output end of the error amplifier, the first end of the optocoupler isolator is connected to the first power supply voltage, the second end of the optocoupler isolator is connected to the second end of the fifth resistor, the third end of the optocoupler isolator is connected to the second power supply voltage, and the fourth end of the optocoupler isolator serves as the output end of the voltage error amplification unit.

6. The current balancing circuit according to claim 1, characterized in that: The current mirror comprises a first transistor, a second transistor, a sixth resistor, a seventh resistor and an eighth resistor; A first end of the sixth resistor is connected to the output end of the output current sampling module, and a second end of the sixth resistor is connected to the collector of the first transistor; A first end of the seventh resistor is connected to the emitter of the first transistor, and a second end of the seventh resistor is grounded; A first end of the eighth resistor is connected to the emitter of the second transistor, and a second end of the eighth resistor is grounded; The base of the second transistor is connected to the base of the first transistor, and the collector of the second transistor is connected to the first input terminal of the output feedback module.

7. The current balancing circuit according to claim 1, characterized in that: The output current sampling module includes an output current sampling unit and a current amplification unit; The output current sampling unit is connected in series with the negative voltage output terminal of the power module, and is used to convert the output current of the power module into a voltage signal and input it into the current amplification unit; The first input end of the current amplifying unit is connected to the first end of the output current sampling unit, the second input end of the current amplifying unit is connected to the second end of the output current sampling unit, and the current amplifying unit is used to amplify the voltage signal.

8. The current balancing circuit according to claim 7, characterized in that: The output current sampling unit includes a sampling resistor, a first end of the sampling resistor serves as a first end of the output current sampling unit, and a second end of the sampling resistor serves as a second end of the output current sampling unit.

9. The current balancing circuit according to claim 7, characterized in that: The current amplifying unit includes an operational amplifier, a ninth resistor, a tenth resistor and an eleventh resistor; The first end of the ninth resistor serves as the first input end of the current amplifying unit, and the second end of the ninth resistor is connected to the non-inverting input end of the operational amplifier; The first end of the tenth resistor serves as the second input end of the current amplifying unit, and the second end of the tenth resistor is connected to the inverting input end of the operational amplifier; The first end of the eleventh resistor is connected to the inverting input end of the operational amplifier, the second end of the eleventh resistor is connected to the output end of the operational amplifier, and the output end of the operational amplifier serves as the output end of the current amplifying unit.

10. The current balancing circuit according to claim 9, characterized in that: The current amplifying unit further includes a twelfth resistor, a first end of the twelfth resistor is connected to a third power supply voltage, and a second end of the twelfth resistor is connected to a non-inverting input end of the operational amplifier.

11. A power supply system, characterized in that: It comprises at least two current balancing circuits as described in any one of claims 1 to 10, and also comprises at least two power supply modules connected in parallel, and the current balancing circuits are connected to the power supply modules in a one-to-one correspondence.

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