A DC power supply output positive and negative line current balancing circuit
By setting up output positive and ground current sampling and amplification circuits and a variable impedance adjustment circuit, the ground current is adjusted to achieve balance, which solves the problem of uneven ground current when non-isolated DC power supplies are connected in parallel, improves system safety and stability, and supports the application of multiple power supplies in parallel.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN JUMICROELECTRONICS TECH CO LTD
- Filing Date
- 2022-11-25
- Publication Date
- 2026-06-30
AI Technical Summary
When multiple non-isolated DC power supplies are used in parallel, the line resistance of the ground wire branches varies greatly, resulting in an uneven distribution of ground current. This may cause some ground wire branches to overheat and burn out due to excessive current.
By setting up an output positive current sampling amplifier circuit, an output ground current sampling amplifier circuit, a variable impedance adjustment circuit, and a positive and negative current signal error comparison amplifier, the magnitude of the output ground current is adjusted in real time to keep it in balance with the output positive current.
It achieves balanced distribution of current in each ground branch, improves system safety and stability, avoids overheating and burnout of ground branches, and supports parallel application of multiple DC power supplies to meet high power output requirements.
Smart Images
Figure CN116260125B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of balanced circuit technology, and more specifically to a DC power supply output positive and negative line current balancing circuit. Background Technology
[0002] With the development of new energy technologies such as hydrogen fuel cells, photovoltaic energy storage, electric vehicle charging, and backup power for communication base stations, the output power of DC power supplies is constantly increasing in many application scenarios. In some applications requiring higher power, a single DC power supply cannot meet the output power requirements, necessitating the parallel connection of multiple DC power supplies. Due to the advantages of non-isolated DC power supplies in low-voltage DC-DC conversion, such as high efficiency, low cost, and simple circuitry, their application is becoming increasingly widespread.
[0003] However, due to the inherent circuit characteristics of non-isolated DC power supplies, their input and output share a common ground. When multiple non-isolated DC power supplies are connected in parallel, their input and output grounds are all connected together. (See [link to relevant documentation]). Figure 3 , Figure 3 This diagram illustrates the impedance composition and current flow of a parallel ground wire branch in a non-isolated DC power supply in the prior art. Since the impedance of each ground wire is affected not only by the internal resistance differences of the DC power supply itself, but also by many factors such as the wire diameter, length, and contact resistance of the external wiring, and these factors are relatively random and difficult to control quantitatively, there is a significant risk of large differences in the line resistance of each ground wire branch. This can easily lead to a large imbalance in the distribution of ground current among the ground wire branches, and in extreme cases, may cause excessive current in some ground wire branches, resulting in overheating and burnout. Summary of the Invention
[0004] To address the problems in existing technologies, this invention provides a DC power supply output positive and negative line current balancing circuit. By setting up a mutually cooperating output positive line current sampling amplification circuit, output ground line current sampling amplification circuit, variable impedance adjustment circuit, and positive and negative current signal error comparison amplifier, the output ground line current can be adjusted in real time to maintain a balanced state with the output positive line current. The solution is simple, low-cost, highly safe, and highly stable. It solves the problems in existing technologies where, when non-isolated DC power supplies are used in parallel, there are large differences in the line resistance of each ground line branch, which can easily cause significant imbalances in the distribution of ground line current among the ground line branches, and even lead to excessive current in some ground line branches, resulting in overheating and burnout.
[0005] This invention provides a DC power supply output positive and negative line current balancing circuit, disposed between the DC power supply and the power output interface. It includes an output positive line current sampling amplification circuit, an output ground line current sampling amplification circuit, a variable impedance adjustment circuit, and a positive and negative current signal error comparison amplifier. The input terminal of the output positive line current sampling amplification circuit is connected to the positive terminal of the DC power supply and the positive terminal of the power output interface. The output terminal of the output positive line current sampling amplification circuit is connected to the input terminal of the positive and negative current signal error comparison amplifier. The input terminal of the output ground line current sampling amplification circuit is connected to the negative terminal of the power output interface and the variable impedance adjustment circuit. The output terminal of the adjustment circuit is connected to the input terminal of the positive and negative current signal error comparator amplifier, the input terminal of the variable impedance adjustment circuit is connected to the output terminal of the positive and negative current signal error comparator amplifier, and the output terminal of the variable impedance adjustment circuit is also connected to the negative terminal of the DC power supply. The positive and negative current signal error comparator amplifier can change the resistance value of the variable impedance adjustment circuit according to the difference between the current of the positive output line of the DC power supply and the current of the DC power supply output ground line, thereby adjusting the current of the DC power supply output ground line to keep it in balance with the current of the DC power supply output positive line.
[0006] In a further improvement, the present invention further includes a positive and negative differential current bypass discharge circuit between the negative terminal of the DC power supply and the negative terminal of the power output interface. The input terminal of the positive and negative differential current bypass discharge circuit is connected to the negative terminal of the power output interface, and the output terminal of the positive and negative differential current bypass discharge circuit is connected to the negative terminal of the DC power supply.
[0007] The present invention is further improved in that the output positive current sampling amplification circuit includes a resistor RS+, an operational amplifier A1, a resistor R1, and a capacitor C1. One end of the resistor RS+ is connected to the positive terminal of the DC power supply and the non-inverting input terminal of the operational amplifier A1. The other end of the resistor RS+ is connected to the positive terminal of the power supply output interface and the inverting input terminal of the operational amplifier A1. The output terminal of the operational amplifier A1 is connected to one end of the resistor R1. The other end of the resistor R1 is connected to one end of the capacitor C1 and the non-inverting input terminal of the positive and negative current signal error comparison amplifier. The other end of the capacitor C1 is grounded.
[0008] The present invention is further improved in that the output ground current sampling amplification circuit includes a resistor RS-, an operational amplifier A2, a resistor R2, and a capacitor C2. One end of the resistor RS- is connected to the negative terminal of the power output interface and the non-inverting input terminal of the operational amplifier A2. The other end of the resistor RS- is connected to the input terminal of the variable impedance adjustment circuit and the inverting input terminal of the operational amplifier A2. The output terminal of the operational amplifier A2 is connected to one end of the resistor R2. The other end of the resistor R2 is connected to one end of the capacitor C2 and the inverting input terminal of the positive and negative current signal error comparison amplifier. The other end of the capacitor C2 is connected to the input terminal of the variable impedance adjustment circuit.
[0009] In a further improvement, the positive and negative current signal error comparison amplifier includes an operational amplifier A3. The non-inverting input terminal of the operational amplifier A3 is connected to the other end of the resistor R1 and one end of the capacitor C1. The inverting input terminal of the operational amplifier A3 is connected to the other end of the resistor R2 and one end of the capacitor C2. The output terminal of the operational amplifier A3 is connected to the input terminal of the variable impedance adjustment circuit.
[0010] The present invention is further improved in that the variable impedance adjustment circuit includes resistors R3, R4, and R5 and a field-effect transistor Q1. The source of the field-effect transistor Q1 is connected to one end of resistor R5, the other end of resistor RS-, and the inverting input terminal of operational amplifier A2. The gate of the field-effect transistor Q1 is connected to the other end of resistor R5 and one end of resistor R4. The drain of the field-effect transistor Q1 is connected to the negative terminal of the DC power supply. The other end of resistor R4 is connected to the output terminal of operational amplifier A3 and one end of resistor R3. The other end of resistor R3 is connected to the other end of capacitor C2.
[0011] In a further improvement, the positive and negative differential current bypass discharge circuit includes a diode D1, the positive terminal of which is connected to the negative terminal of the power output interface, and the negative terminal of which is connected to the negative terminal of the DC power supply.
[0012] In a further improvement to the present invention, the field-effect transistor Q1 is an N-channel field-effect transistor, and the source and drain of the field-effect transistor Q1 can be interchanged.
[0013] In a further improvement to the present invention, both operational amplifier A1 and operational amplifier A2 can be replaced with current amplifiers.
[0014] In a further improvement to the present invention, the diode D1 can be replaced with a field-effect transistor or an insulated-gate bipolar transistor.
[0015] Compared with the prior art, the beneficial effects of the present invention are: it provides a DC power supply output positive and negative line current balancing circuit, which, by setting up a mutually cooperating output positive line current sampling amplifier circuit, output ground line current sampling amplifier circuit, variable impedance adjustment circuit, and positive and negative current signal error comparison amplifier, can adjust the current of the DC power supply output ground line by changing the resistance value of the variable impedance adjustment circuit according to the difference between the current of the DC power supply output positive line and the current of the DC power supply output ground line, so as to keep it in balance with the current of the DC power supply output positive line. The solution is simple, low-cost, safe, and stable. It solves the problem in the prior art that when non-isolated DC power supplies are used in parallel, there are large differences in the line resistance of each ground line branch, which can easily cause a large imbalance in the distribution of ground line current in each ground line branch, and even cause some ground line branches to overheat and burn out due to excessive current. Furthermore, many non-isolated solar photovoltaic modules or hydrogen fuel cell charging modules on the market design their DC power output positive and negative line current balancing circuits by placing the output current sampling resistor on the negative terminal of the power output, i.e., the power supply's ground line. If such power modules are used in parallel, the uncontrollable ground current caused by the random factors affecting the aforementioned power supply ground line resistance will prevent the voltage drop across the current sampling resistor from accurately reflecting the actual output current of the power supply. This will cause the internal control chip of the power supply to receive incorrect current signals, potentially leading to loss of control and abnormal power supply operation. Therefore, such power modules need to address the ground current distribution issue before they can be used in parallel. The DC power output positive and negative line current balancing circuit of this invention can also solve this problem, allowing multiple DC power supplies to be used in parallel to meet high power output requirements. Attached Figure Description
[0016] To more clearly illustrate the solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0017] Figure 1 This is a circuit diagram showing the positive and negative line current balancing circuit of the DC power supply output of the present invention (dashed box portion).
[0018] Figure 2 This is a block diagram of the DC power supply output positive and negative line current balancing circuit of the present invention;
[0019] Figure 3 This is a schematic diagram of the impedance composition and current flow direction of a parallel ground wire branch in a non-isolated DC power supply in the prior art. Detailed Implementation
[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.
[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.
[0023] like Figure 1 and 2 As shown, this invention provides a DC power supply output positive and negative line current balancing circuit, disposed between the DC power supply and the power output interface. It includes an output positive line current sampling amplifier circuit, an output ground line current sampling amplifier circuit, a variable impedance adjustment circuit, and a positive and negative current signal error comparator amplifier. The input terminal of the output positive line current sampling amplifier circuit is connected to the positive terminal of the DC power supply and the positive terminal of the power output interface. The output terminal of the output positive line current sampling amplifier circuit is connected to the input terminal of the positive and negative current signal error comparator amplifier. The input terminal of the output ground line current sampling amplifier circuit is connected to the negative terminal of the power output interface and the output terminal of the variable impedance adjustment circuit. The output terminal of the output ground line current sampling amplifier circuit is connected to the input terminal of the positive and negative current signal error comparator amplifier. The input terminal of the variable impedance adjustment circuit is connected to the output terminal of the positive and negative current signal error comparator amplifier. The output terminal of the variable impedance adjustment circuit is also connected to the negative terminal of the DC power supply. The positive and negative current signal error comparator amplifier can adjust the resistance value of the variable impedance adjustment circuit according to the difference between the current of the DC power supply output positive line and the current of the DC power supply output ground line, thereby adjusting the current of the DC power supply output ground line to maintain balance with the current of the DC power supply output positive line. Please refer to [link to relevant documentation]. Figure 2In this embodiment, the circuit works by connecting a low-resistance current sampling resistor in series with both the positive output line and the ground output line of the DC power supply. The ground output line of the DC power supply can also be called the negative output line of the DC power supply. The current samples from the positive output line and the ground output line of the DC power supply are amplified and sent to an error comparator amplifier for comparison. The output signal of the comparator amplifier drives a variable impedance adjustment circuit to adjust the impedance of the ground output line of the DC power supply, thereby changing the voltage drop of the ground output line of the DC power supply and achieving the purpose of balanced output of the ground output line current following the positive output line current of the DC power supply.
[0024] like Figure 1 As shown, the output positive line current sampling amplifier circuit includes a resistor RS+, an operational amplifier A1, a resistor R1, and a capacitor C1. One end of the resistor RS+ is connected to the positive terminal of the DC power supply and the non-inverting input terminal of the operational amplifier A1. The other end of the resistor RS+ is connected to the positive terminal of the power supply output interface and the inverting input terminal of the operational amplifier A1. The output terminal of the operational amplifier A1 is connected to one end of the resistor R1. The other end of the resistor R1 is connected to one end of the capacitor C1 and the non-inverting input terminal of the positive and negative current signal error comparator amplifier. The other end of the capacitor C1 is grounded. In this embodiment, the output positive line current sampling amplifier circuit is used to collect the current of the positive line output by the DC power supply.
[0025] like Figure 1 As shown, the output ground current sampling amplifier circuit includes a resistor RS-, an operational amplifier A2, a resistor R2, and a capacitor C2. One end of the resistor RS- is connected to the negative terminal of the power output interface and the non-inverting input of the operational amplifier A2. The other end of the resistor RS- is connected to the input of the variable impedance adjustment circuit and the inverting input of the operational amplifier A2. The output of the operational amplifier A2 is connected to one end of the resistor R2. The other end of the resistor R2 is connected to one end of the capacitor C2 and the inverting input of the positive and negative current signal error comparison amplifier. The other end of the capacitor C2 is connected to the input of the variable impedance adjustment circuit. In this embodiment, the output positive ground current sampling amplifier circuit is used to collect the current of the DC power supply output ground wire.
[0026] like Figure 1 As shown, the positive and negative current signal error comparator amplifier includes operational amplifier A3. The non-inverting input of operational amplifier A3 is connected to the other end of resistor R1 and one end of capacitor C1, and the inverting input of operational amplifier A3 is connected to the other end of resistor R2 and one end of capacitor C2. The output of operational amplifier A3 is connected to the input of the variable impedance adjustment circuit. In this embodiment, the positive and negative current signal error comparator amplifier is used to compare the current of the positive line of the DC power supply output and the current of the DC power supply output ground line, and outputs the difference to the variable impedance adjustment circuit.
[0027] like Figure 1As shown, the variable impedance adjustment circuit includes resistors R3, R4, and R5, and a field-effect transistor Q1. The source of the field-effect transistor Q1 is connected to one end of resistor R5, the other end of resistor RS-, and the inverting input of operational amplifier A2. The gate of the field-effect transistor Q1 is connected to the other end of resistor R5 and one end of resistor R4. The drain of the field-effect transistor Q1 is connected to the negative terminal of the DC power supply. The other end of resistor R4 is connected to the output terminal of operational amplifier A3 and one end of resistor R3. The other end of resistor R3 is connected to the other end of capacitor C2. In this embodiment, the variable impedance adjustment circuit is used to adjust the impedance of the DC power supply output ground line, thereby changing the voltage drop of the DC power supply output ground line.
[0028] like Figure 1 As shown, the positive and negative differential current bypass discharge circuit includes diode D1. The positive terminal of diode D1 is connected to the negative terminal of the power output interface, and the negative terminal of diode D1 is connected to the negative terminal of the DC power supply.
[0029] In this embodiment, the positive current Io1+ of the DC power supply is sampled by a low-resistance current sampling resistor RS+. Since this current signal is as low as millivolts to tens of millivolts, it is amplified by operational amplifier A1 and used as a reference voltage. After being filtered by resistor R1 and capacitor C1, it is sent to the non-inverting input of error comparator operational amplifier A3. Correspondingly, the ground current Io1- of the DC power supply is sampled by resistor RS-, amplified by operational amplifier A2, and then sent to the inverting input of operational amplifier A3 via resistor R2 for comparison with the reference voltage output by operational amplifier A1. After the two voltage values are compared by operational amplifier A3, operational amplifier A3 outputs an analog voltage signal that drives a low-on-resistance field-effect transistor Q1 via resistor R4. Here, the field-effect transistor Q1 acts as a variable resistor controlled by the output voltage of operational amplifier A3, thus adjusting the voltage drop across the DC power supply's output ground line. When the positive line current Io1+ of the DC power supply is amplified by operational amplifier A1 to generate a reference voltage, if the ground line current Io1- of the DC power supply is lower than the positive line current Io1+, the voltage generated after amplification by operational amplifier A2 will also be lower than the reference voltage output by operational amplifier A1. Operational amplifier A3 will then output a higher voltage to drive the field-effect transistor Q1, causing Q1 to be in a low-impedance conducting state. This reduces the voltage drop across the ground line branch of the DC power supply, making it easier for current to flow through the ground line branch, and increasing Io1- to achieve a balance state close to or equal to Io1+. The process is reversed, with the same result. The balancing circuits for other parallel DC power supplies are also the same, such as those for Io2+ and Io2-, which follow the same process.
[0030] In practical applications, slight errors in the resistance values of current sampling resistors RS+ and RS-, as well as the amplification factors of operational amplifiers A1 and A2, can cause a slight difference between the positive and negative line current signals and the actual current. Therefore, a diode D1 is added to the DC power supply output ground circuit as a bypass discharge channel for the differential current. Under abnormal conditions, diode D1 can also fully carry the current of the DC power supply output ground branch, serving as a redundant channel for the DC power supply output ground, increasing the stability and safety of the DC power supply output positive and negative line current balancing circuit of this invention. Resistor R3 and capacitor C2 provide feedback compensation for operational amplifier A3 in the circuit. Resistor R5 acts as a pull-down resistor for the gate of field-effect transistor Q1, preventing the gate from being floating in a high-impedance driving state.
[0031] like Figure 1 As shown, the field-effect transistor Q1 is an N-channel field-effect transistor, and the source and drain of the field-effect transistor Q1 can be interchanged. In this embodiment, the N-channel field-effect transistor Q1 is used as a controllable impedance device. Since the conduction of the field-effect transistor is bidirectional, the source and drain of the field-effect transistor Q1 in this circuit can be used interchangeably, and the purpose of balancing the positive and negative line currents of the DC power supply output of this invention can still be achieved.
[0032] like Figure 1 As shown, operational amplifiers A1 and A2 can both be replaced with current amplifiers. In this embodiment, operational amplifiers A1 and A2 are used to amplify the current in the positive and ground lines of the DC power supply output. Replacing them with current amplifiers can also achieve the purpose of balancing the positive and negative currents of the DC power supply output in this invention. The signal filtering and compensation circuits of the amplification and comparison circuits can use either series and parallel connections of resistors and capacitors, or individual series or parallel connections of resistors and capacitors, as long as the function of the signal filtering and compensation circuits can be achieved.
[0033] like Figure 1 As shown, diode D1 can be replaced with a field-effect transistor or an insulated-gate bipolar transistor. In this embodiment, diode D1 serves as a bypass discharge for the positive and negative differential current and a redundant circuit for the DC power supply output ground line. Replacing the device used with a field-effect transistor or an insulated-gate bipolar transistor can also achieve the purpose of balancing the positive and negative line currents of the DC power supply output of this invention.
[0034] As can be seen from the above, the present invention provides a DC power supply output positive and negative line current balancing circuit. By setting up a mutually cooperating output positive line current sampling amplifier circuit, output ground line current sampling amplifier circuit, variable impedance adjustment circuit, and positive and negative current signal error comparison amplifier, the positive and negative current signal error comparison amplifier can change the resistance value of the variable impedance adjustment circuit according to the difference between the current of the DC power supply output positive line and the current of the DC power supply output ground line, thereby adjusting the current of the DC power supply output ground line and keeping it in balance with the current of the DC power supply output positive line. The solution is simple, low-cost, highly safe, and highly stable. It solves the problem in the prior art that when non-isolated DC power supplies are used in parallel, there are large differences in the line resistance of each ground line branch, which easily causes a large imbalance in the distribution of ground line current in each ground line branch, and even leads to excessive current in some ground line branches, causing them to overheat and burn out. Furthermore, many non-isolated solar photovoltaic modules or hydrogen fuel cell charging modules on the market design their DC power output positive and negative line current balancing circuits by placing the output current sampling resistor on the negative terminal of the power output, i.e., the power supply's ground line. If such power modules are used in parallel, the uncontrollable ground current caused by the random factors affecting the aforementioned power supply ground line resistance will prevent the voltage drop across the current sampling resistor from accurately reflecting the actual output current of the power supply. This will cause the internal control chip of the power supply to receive incorrect current signals, potentially leading to loss of control and abnormal power supply operation. Therefore, such power modules need to address the ground current distribution issue before they can be used in parallel. The DC power output positive and negative line current balancing circuit of this invention can also solve this problem, allowing multiple DC power supplies to be used in parallel to meet high power output requirements.
[0035] The specific embodiments described above are preferred embodiments of the present invention and are not intended to limit the specific scope of the present invention. The scope of the present invention includes, but is not limited to, these specific embodiments. All equivalent changes made in accordance with the present invention are within the protection scope of the present invention.
Claims
1. A DC power supply output positive and negative line current balancing circuit, disposed between the DC power supply and the power supply output interface, characterized in that: The system includes an output positive line current sampling amplifier circuit, an output ground line current sampling amplifier circuit, a variable impedance adjustment circuit, and a positive and negative current signal error comparator amplifier. The input terminal of the output positive line current sampling amplifier circuit is connected to the positive terminal of the DC power supply and the positive terminal of the power supply output interface. The output terminal of the output positive line current sampling amplifier circuit is connected to the input terminal of the positive and negative current signal error comparator amplifier. The input terminal of the output ground line current sampling amplifier circuit is connected to the negative terminal of the power supply output interface and the output terminal of the variable impedance adjustment circuit. The output terminal of the output ground line current sampling amplifier circuit is connected to the input terminal of the positive and negative current signal error comparator amplifier. The input terminal of the variable impedance adjustment circuit is connected to the output terminal of the positive and negative current signal error comparator amplifier. The output terminal of the variable impedance adjustment circuit is also connected to the negative terminal of the DC power supply. The positive and negative current signal error comparator amplifier can adjust the resistance value of the variable impedance adjustment circuit according to the difference between the current of the DC power supply output positive line and the current of the DC power supply output ground line, thereby adjusting the current of the DC power supply output ground line to maintain balance with the current of the DC power supply output positive line.
2. The DC power supply output positive and negative line current balancing circuit according to claim 1, characterized in that: A positive-negative differential current bypass discharge circuit is also provided between the negative terminal of the DC power supply and the negative terminal of the power output interface. The input terminal of the positive-negative differential current bypass discharge circuit is connected to the negative terminal of the power output interface, and the output terminal of the positive-negative differential current bypass discharge circuit is connected to the negative terminal of the DC power supply.
3. The DC power supply output positive and negative line current balancing circuit according to claim 2, characterized in that: The output positive current sampling amplification circuit includes a resistor RS+, an operational amplifier A1, a resistor R1, and a capacitor C1. One end of the resistor RS+ is connected to the positive terminal of the DC power supply and the non-inverting input terminal of the operational amplifier A1. The other end of the resistor RS+ is connected to the positive terminal of the power supply output interface and the inverting input terminal of the operational amplifier A1. The output terminal of the operational amplifier A1 is connected to one end of the resistor R1. The other end of the resistor R1 is connected to one end of the capacitor C1 and the non-inverting input terminal of the positive and negative current signal error comparison amplifier. The other end of the capacitor C1 is grounded.
4. The DC power supply output positive and negative line current balancing circuit according to claim 3, characterized in that: The output ground current sampling amplification circuit includes a resistor RS-, an operational amplifier A2, a resistor R2, and a capacitor C2. One end of the resistor RS- is connected to the negative terminal of the power output interface and the non-inverting input terminal of the operational amplifier A2. The other end of the resistor RS- is connected to the input terminal of the variable impedance adjustment circuit and the inverting input terminal of the operational amplifier A2. The output terminal of the operational amplifier A2 is connected to one end of the resistor R2. The other end of the resistor R2 is connected to one end of the capacitor C2 and the inverting input terminal of the positive and negative current signal error comparison amplifier. The other end of the capacitor C2 is connected to the input terminal of the variable impedance adjustment circuit.
5. The DC power supply output positive and negative line current balancing circuit according to claim 4, characterized in that: The positive and negative current signal error comparison amplifier includes an operational amplifier A3. The non-inverting input terminal of the operational amplifier A3 is connected to the other end of the resistor R1 and one end of the capacitor C1. The inverting input terminal of the operational amplifier A3 is connected to the other end of the resistor R2 and one end of the capacitor C2. The output terminal of the operational amplifier A3 is connected to the input terminal of the variable impedance adjustment circuit.
6. The DC power supply output positive and negative line current balancing circuit according to claim 5, characterized in that: The variable impedance adjustment circuit includes resistors R3, R4, and R5, and a field-effect transistor Q1. The source of the field-effect transistor Q1 is connected to one end of resistor R5, the other end of resistor RS-, and the inverting input of operational amplifier A2. The gate of the field-effect transistor Q1 is connected to the other end of resistor R5 and one end of resistor R4. The drain of the field-effect transistor Q1 is connected to the negative terminal of the DC power supply. The other end of resistor R4 is connected to the output of operational amplifier A3 and one end of resistor R3. The other end of resistor R3 is connected to the other end of capacitor C2.
7. The DC power supply output positive and negative line current balancing circuit according to claim 6, characterized in that: The positive and negative differential current bypass discharge circuit includes a diode D1, the positive terminal of which is connected to the negative terminal of the power output interface, and the negative terminal of which is connected to the negative terminal of the DC power supply.
8. The DC power supply output positive and negative line current balancing circuit according to claim 7, characterized in that: The field-effect transistor Q1 is an N-channel field-effect transistor, and the source and drain of the field-effect transistor Q1 can be interchanged.
9. The DC power supply output positive and negative line current balancing circuit according to claim 7, characterized in that: Both operational amplifier A1 and operational amplifier A2 can be replaced with current amplifiers.
10. The DC power supply output positive and negative line current balancing circuit according to claim 7, characterized in that: The diode D1 can be replaced with a field-effect transistor or an insulated-gate bipolar transistor.