Current sharing circuit composed of operational amplifiers

Abstract

The invention relates to the technical field of current sharing control, in particular to a current sharing circuit composed of operational amplifiers. Comprising a group of main DCDC modules and at least one group of secondary DCDC modules which form a multi-stage parallel structure, and each group of secondary DCDC modules is provided with a group of operational amplifiers in a one-to-one correspondence manner; the signal end of each operational amplifier is electrically connected with the Vout and the feedback pin of the corresponding secondary DCDC module and the Vout of the primary DCDC module or the secondary DCDC module. The periphery of the operational amplifier realizes sampling, transmission, feedback, filtering and other operations through resistor connection. According to the scheme, triodes and MOS (Metal Oxide Semiconductor) tubes are abandoned, and the current of each parallel structure is actively detected and adjusted through a closed-loop control circuit instead of depending on the physical characteristics of a power device, so that the current is strictly equal; the power loss between DCDC is dispersed, the temperature rise is reduced, and the overall heat dissipation stability is improved; the circuit is simple, few in components and low in cost.

Description

Technical Field

[0001] This invention relates to the field of current sharing control technology, and more specifically to a current sharing circuit composed of operational amplifiers. Background Technology

[0002] In existing technologies, current sharing circuits are mostly composed of ordinary transistors and MOSFETs.

[0003] Transistors are inefficient, have slow switching speeds, complex circuits, high costs, and are difficult to manage thermally; MOSFETs have poor dynamic current sharing and are extremely sensitive to layout symmetry and parameters. Due to differences in transconductance parameters, uneven current distribution may occur, requiring the addition of components such as current sharing beads and inductors, which increases costs.

[0004] Some current sharing circuit schemes use operational amplifiers, but each unit requires multiple sets of operational amplifiers (e.g., CN113949279A contains 3, CN206226261U contains 5). Current sharing needs to be achieved through multi-stage amplification (differential amplification, loop control, active rectification, etc.), resulting in multiple circuit layers and complex wiring. Alternatively, an operational amplifier is needed in conjunction with a constant voltage reference source, transistors, and Zener diodes to adjust the feedback closed loop involving multiple components to achieve current sharing control (e.g., CN102843838B), which results in high logic complexity. Summary of the Invention

[0005] The technical problem to be solved by this invention is: complex circuit structure, cumbersome adjustment logic, reliance on auxiliary devices, and insufficient balance between versatility and cost.

[0006] To address this, the present invention provides a current sharing circuit composed of operational amplifiers, which no longer relies on the physical characteristics of the power devices themselves. Instead, it actively detects and adjusts the current of each parallel structure through a closed-loop control circuit with a minimalist architecture, ensuring that they are strictly equal. This significantly reduces the number of devices, lowers the circuit size and wiring complexity, and makes it easier to integrate into small power modules.

[0007] The technical solution adopted by this invention to solve its technical problem is: A current sharing circuit using operational amplifiers includes, A primary DC-DC module and at least one secondary DC-DC module, wherein the primary DC-DC module and the secondary DC-DC module together constitute at least two levels of parallel structure; Operational amplifiers configured one-to-one with each of the secondary DC-DC modules; The resistors and capacitors include a sampling resistor for acquiring signals and adjusting sampling sensitivity, a transmission resistor for transmitting signals and adjusting signal strength, and a feedback resistor for constructing a feedback loop and adjusting feedback strength. The capacitors are filter capacitors for filtering out high-frequency interference. The resistors and capacitors are distributed around the operational amplifier. The Vout pins of the primary DC-DC module and the secondary DC-DC module are connected in parallel to the load; the signal terminals of each operational amplifier are electrically connected to the Vout pin, feedback pin, and Vout pin of the corresponding secondary DC-DC module and the primary or secondary DC-DC module of the preceding stage.

[0008] Using the above technical solution, output current balancing of all main and secondary DC-DC modules is achieved through cascaded voltage comparison and feedback adjustment. A cascaded architecture of "main DC-DC module + at least one secondary DC-DC module" (at least two stages in total) is adopted, with no upper limit on the number of cascaded modules, adapting to different power demand scenarios. Through a one-to-one correspondence between operational amplifiers and secondary DC-DC modules, independent and precise adjustment of each stage is ensured, and the functions of resistors and capacitors are clearly defined (sampling, feedback, filtering), avoiding interference from multiple modules operating in parallel.

[0009] Furthermore, the Vout of the main DC-DC module and the secondary DC-DC module is electrically connected to the first pin of a set of sampling resistors, and the second pin of the set of sampling resistors is electrically connected to the inverting input (negative terminal) of the operational amplifier corresponding to the next secondary DC-DC module.

[0010] By adopting the above technical solution, the sampling resistor can be flexibly adapted to the sampling requirements of different current ranges through resistance value adjustment, accurately acquiring the voltage signal (reflecting the output current) corresponding to the main DCDC module Vout, providing a stable and adjustable reference for voltage comparison of the secondary DCDC module connected to it, and ensuring the accuracy and adaptability of the initial reference signal for cascade adjustment.

[0011] Furthermore, a set of feedback resistors and a set of filter capacitors are connected in parallel between the inverting input (negative terminal) and the output terminal of the operational amplifier.

[0012] By adopting the above technical solution, the feedback resistor can optimize the closed-loop feedback strength of the operational amplifier through resistance value adjustment, ensuring the linearity and stability of the adjustment; the filter capacitor filters out high-frequency interference signals at the output end, avoiding misjudgment of current adjustment caused by signal fluctuations. The two work together to improve the reliability and flexibility of the first-stage adjustment.

[0013] Furthermore, the feedback pin (FB) of the secondary DC-DC module is electrically connected to the first pin of another set of feedback resistors, and the second pin of the set of feedback resistors is electrically connected to the output terminal of the corresponding operational amplifier.

[0014] The set of feedback resistors can precisely control the strength of the adjustment signal transmitted to the FB pin of the secondary DC-DC module by adjusting the resistance value, without intermediate conversion links, thus reducing signal loss.

[0015] Furthermore, the Vout of the secondary DC-DC module is electrically connected to the first pin of a corresponding set of sampling resistors, and the second pin of the sampling resistors is electrically connected to the inverting input (negative terminal) of the next stage operational amplifier.

[0016] This set of sampling resistors can be adjusted to suit the sampling requirements of different power levels of the secondary DC-DC module, accurately acquiring the voltage signal corresponding to Vout of the secondary DC-DC module, providing a stable and adjustable reference for voltage comparison with the next secondary DC-DC module (if any), continuing the cascaded adjustment signal acquisition link, and ensuring the accuracy and adaptability of current deviation identification.

[0017] Furthermore, a set of transmission resistors is connected between the Vout of the secondary DC-DC module and the non-inverting input (positive terminal) of the corresponding set of operational amplifiers.

[0018] The transmission resistor can control the transmission strength of the Vout signal of the secondary DC-DC module by adjusting its resistance value, so that the corresponding operational amplifier can accurately identify the current deviation between the primary and secondary stages or the current deviation between adjacent stages, providing a reliable basis for adjustment and adapting to the extremely simple logic of "no additional signal conversion" and the adjustment needs of different power scenarios.

[0019] Furthermore, a set of filter capacitors is connected in parallel between the power supply terminals and ground of the main DC-DC module and the secondary DC-DC module to filter out high-frequency noise at the power supply terminal and stabilize the operating voltage of the operational amplifier.

[0020] Furthermore, another set of transmission resistors is provided between the secondary DC-DC module and the corresponding operational amplifier, and the transmission resistors are grounded simultaneously.

[0021] This forms a signal transmission and voltage divider loop of "secondary Vout - operational amplifier - ground". It not only achieves stable transmission of the secondary DC-DC module voltage signal, but also adjusts the signal transmission strength and voltage division ratio by adjusting the resistance value. No additional voltage divider components are required, simplifying the link and improving the accuracy of current deviation identification.

[0022] The beneficial effects of this invention are: 1. Meets the requirements for uniform heat dissipation of DC-DC chips, improving the lifespan of components (chips, resistors, capacitors, inductors); 2. Reduced cost, with only capacitors and resistors in the external circuitry; 3. The design is simple and the peripheral circuit is easy to understand. Nowadays, the design of cars is becoming more and more minimalist, which has squeezed the design of lamps and made the space for component placement increasingly larger. This eliminates most of the components and greatly reduces the design difficulty. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 This is a block diagram of the current sharing circuit of the present invention; Figure 2 This is the circuit diagram used in this invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] Reference Figure 1 , Figure 2 A current sharing circuit using operational amplifiers includes a main DC-DC module, a secondary DC-DC module, operational amplifiers, resistors, and capacitors.

[0029] The system includes one main DC-DC module and at least one secondary DC-DC module, which together form a multi-stage parallel structure. Operational amplifiers are configured one-to-one with each secondary DC-DC module. Resistors and capacitors are configured one-to-one with the corresponding operational amplifiers. The resistors include sampling resistors for acquiring signals and adjusting sampling sensitivity, transmission resistors for transmitting signals and adjusting signal strength, and feedback resistors for constructing feedback loops and adjusting feedback strength. The capacitors are filter capacitors used to filter out high-frequency interference.

[0030] The output terminals (Vout) of the main DC-DC module and the secondary DC-DC module are connected to the load in parallel; the signal terminal of each operational amplifier is electrically connected to the Vout, feedback pin of the corresponding secondary DC-DC module, and the Vout of the preceding main DC-DC module or secondary DC-DC module.

[0031] It should be noted that in this solution, the main DC-DC module and the secondary DC-DC module are powered by the BCM, and the main DC-DC module and the secondary DC-DC module are composed of BUCK circuits; the operational amplifier is designed and configured as a differential amplifier.

[0032] This solution can be implemented using an operational amplifier and matching resistors and capacitors to connect the outputs of two DC-DC converters together to share current. This disperses power loss between the two DC-DC converters, thereby reducing temperature rise and improving overall thermal stability. This eliminates the potential need for external heatsinks, thus reducing system design complexity, size, and overall cost.

[0033] Reference Figure 2 In one embodiment, the phase control strategy for the switching transistor drive signals of the main DC-DC module and the secondary DC-DC module adopts a 180-degree phase-shift circuit structure. The 180-degree phase-shift circuit has the following advantages: a. Switching losses on each path will be reduced. This results in better electromagnetic interference (EMI) and heat dissipation performance.

[0034] b. Phase-shifting circuits can reduce input and output ripple current.

[0035] Reference Figure 2 In one embodiment, a current sharing circuit using operational amplifiers is illustrated, taking the secondary DC-DC module with three groups as an example: It should be noted that, for ease of understanding, the group of secondary DC-DC modules connected to the primary DC-DC module (DCDC1) is called the first-level DC-DC module (DCDC2), the next group of secondary DC-DC modules connected to the first-level DC-DC module is called the second-level DC-DC module (DCDC3), and so on.

[0036] Meanwhile, the operational amplifier corresponding to the first-stage DC-DC module (DCDC1) is called the first operational amplifier (U1), the operational amplifier corresponding to the second-stage DC-DC module is called the second operational amplifier (U2), and so on. The inductor in the main DC-DC module is L1, the inductor in the first-stage DC-DC module is L2, and so on.

[0037] The sampling resistors include R4, R9, and R14; the transmission resistors include R1, R3, R6, R8, R11, and R13; the feedback resistors include R5, R10, and R15; and the filter capacitors include C2, C4, and C6.

[0038] Specifically, the SW pin of the DCDC1 step-down chip is connected to pin 1 of inductor L1, and pin 2 of inductor L1 (which serves as the Vout of the main DCDC module, referred to as Vout1, and so on) is connected to the load. Pin 2 of inductor L1 is also connected to resistor R4, which is then connected to the negative terminal of U1. The negative terminal and the output terminal (pin 4) of U1 are connected in parallel with resistor R5 and filter capacitor C2. The FB2 feedback pin of the DCDC2 step-down chip is connected to resistor R3, which is then connected to the output terminal (pin 4) of U1. The SW pin of the DCDC2 step-down chip is connected to pin 1 of inductor L2, and pin 2 of inductor L2 (Vout2) is connected to the load. Pin 2 of inductor L2 is connected to resistor R9, which is then connected to the negative terminal of U2. The negative terminal and the output terminal (pin 4) of U2 are connected in parallel with resistor R10 and filter capacitor C4. Pin 2 of inductor L2 is also connected to resistor R1, which is then connected to the positive terminal of U1.

[0039] The SW pin of the DC-DC3 step-down chip is connected to pin 1 of inductor L3. Pin 2 (Vout3) of inductor L3 is connected to the load. Pin 2 of inductor L3 is connected to resistor R14, which is then connected to the negative terminal of U3. Resistor R15 and filter capacitor C16 are connected in parallel between the negative terminal and the output terminal (pin 4) of U3. Pin 2 of inductor L3 is also connected to resistor R6, which is then connected to the positive terminal of U2. The FB3 feedback pin of the DC-DC3 step-down chip is connected to resistor R8, which is then connected to the output terminal (pin 4) of U2.

[0040] In this embodiment, the SW pin of the DC-DC4 step-down chip is connected to the 1st pin of inductor L4, the 2nd pin (Vout4) of inductor L4 is connected to the load, the 2nd pin of inductor L4 is connected to resistor R11, and resistor R11 is then connected to the positive terminal of U3. The FB4 feedback pin of the DC-DC4 step-down chip is connected to resistor R13, and R13 is then connected to the output terminal (pin 4) of U3.

[0041] Current sharing among the four buck circuits can be achieved using a simple operational amplifier circuit (including the amplifier and connected resistors and filter capacitors) to compare the inductor currents of the primary (main DC-DC module) and secondary (secondary DC-DC module). The operational amplifier circuit output adjusts the load current of the secondary DC-DC module by controlling the output voltage of the FB pin of the primary or secondary DC-DC module to keep the difference between the primary and secondary output currents zero. When the primary and secondary output voltages are matched, the output of the operational amplifier is equal to the reference voltage (FB) of the buck regulator (no current is generated at the feedback node when the two phases are perfectly matched). Specifically: The function of operational amplifier U1 is: when the current supplied by the primary side is greater than that of the secondary side, the output FB2 of the operational amplifier will decrease, causing the voltage of Vout2 to rise slightly. This will allow Vout2 to supply more current until current balance is achieved. The function of operational amplifier U2 is: when the current of Vout2 is greater than that of Vout3, the output FB3 of the operational amplifier will decrease, causing the voltage of Vout3 to rise slightly. This will allow Vout3 to supply more current until current balance is achieved. The function of operational amplifier U3 is: when the current of Vout3 is greater than that of Vout4, the output FB4 of the operational amplifier will decrease, causing the voltage of Vout4 to rise slightly. This will allow Vout4 to supply more current until current balance is achieved. Ultimately, the currents of the current sharing circuit output Vout1, Vout2, Vout3, and Vout4 are balanced.

[0042] Reference Figure 2 In one set of embodiments, a current sharing circuit composed of operational amplifiers further includes transmission resistors R2, R7, and R12, and filter capacitors C1, C3, and C5, based on the previous embodiment.

[0043] Among them, the first pin of resistor R2 (the transmission resistor used to transmit the reference signal Vout1 and adjust the signal transmission strength by adjusting the resistance value) is electrically connected to Vout2 of DCDC2 through resistor R1, the second pin is electrically connected to the non-inverting input terminal (positive terminal) of U1, and the third pin is grounded, forming a signal transmission and voltage divider loop of "secondary Vout2 - operational amplifier U1 - ground".

[0044] The first pin of resistor R7 (used to transmit the Vout1 reference signal and adjust the signal transmission strength by adjusting the resistance value) is electrically connected to Vout3 of DCDC3 through resistor R6, the second pin is electrically connected to the non-inverting input (positive terminal) of U2, and the third pin is grounded, forming a signal transmission and voltage divider loop of "secondary Vout3 - operational amplifier U2 - ground".

[0045] The first pin of resistor R12 (used to transmit the Vout1 reference signal and adjust the signal transmission strength by adjusting the resistance value) is electrically connected to Vout4 of DCDC4 through resistor R11, the second pin is electrically connected to the non-inverting input (positive terminal) of U3, and the third pin is grounded, forming a signal transmission and voltage divider loop of "secondary Vout4 - operational amplifier U3 - ground".

[0046] One end of filter capacitor C1 is connected to the power supply terminal of U1, and the other end is grounded. One end of filter capacitor C2 is connected to the power supply terminal of U2, and the other end is grounded; one end of filter capacitor C3 is connected to the power supply terminal of U3, and the other end is grounded.

[0047] The power loss is evenly distributed to avoid overload of a single module, eliminating the need for an external heat sink and reducing system cost, size and integration complexity; the resistors have clear functions and integrated adjustment, the filter capacitors are dedicated to stabilizing the power supply of the operational amplifier, and the three-point connection of R2, R6 and R12 simplifies the signal link and improves transmission stability. No additional adjustment or filtering components are required, which balances flexibility, economy and reliability and adapts to the needs of different power and current ranges.

[0048] Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the invention, which can be implemented in various forms. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as the basis of the claims and as a representative basis for teaching those skilled in the art to employ the invention differently with any suitable detailed structure contemplated. In particular, features presented and described in the individual dependent claims may be applied in combination, and any advantageous combinations of these claims are disclosed herein.

[0049] Furthermore, it is anticipated that structural elements can be generated by applying three-dimensional (3D) printing technology. Therefore, any reference to structural elements is intended to cover any computer-executable instructions that instruct a computer to generate such a structural element using 3D printing technology or similar computer-controlled manufacturing techniques. Additionally, any such reference to structural elements is also intended to cover computer-readable media carrying such computer-executable instructions.

[0050] Furthermore, the terminology and phrases used herein are not intended to be limiting, but rather to provide an understandable description of the invention. As used herein, the term "a" or "an" is defined as one or more. As used herein, the term "multiple" is defined as two or more. As used herein, the term "another" is defined as at least a second or more. As used herein, the terms "comprising" and / or "having" are defined as including (i.e., open-ended language). As used herein, the term "link" is defined as a connection, although not necessarily a direct connection.

[0051] The invention described herein can obviously be modified in many ways. These changes should not be considered as a departure from the spirit and scope of the invention, and all such modifications, which will be obvious to those skilled in the art, are intended to be included within the scope of the appended claims.

[0052] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. A current-sharing circuit using operational amplifiers, characterized in that, include The system comprises a primary DC-DC module and a secondary DC-DC module, wherein the primary DC-DC module and at least one set of secondary DC-DC modules form a multi-level parallel structure, and the Vout of the primary DC-DC module and the secondary DC-DC module are connected to the load in parallel. An operational amplifier is configured to correspond one-to-one with each of the secondary DC-DC modules; the signal terminal of each operational amplifier is electrically connected to the Vout, feedback pin of the corresponding secondary DC-DC module, and the Vout of the preceding primary DC-DC module or secondary DC-DC module. Resistors and capacitors are configured corresponding to each group of operational amplifiers. The resistors include sampling resistors, transmission resistors, and feedback resistors, and the capacitors are filter capacitors.

2. The current sharing circuit using operational amplifiers according to claim 1, characterized in that, A set of sampling resistors is connected in series between Vout of the main DC-DC module and the negative terminal of the corresponding operational amplifier. A set of sampling resistors is also connected in series between Vout of the secondary DC-DC module and the negative terminal of the operational amplifier corresponding to the next-level secondary DC-DC module.

3. The current sharing circuit using operational amplifiers according to claim 2, characterized in that, A set of feedback resistors and a set of capacitors are connected in parallel between the negative terminal and the output terminal of the operational amplifier.

4. The current sharing circuit using operational amplifiers according to claim 3, characterized in that, The Vout of the secondary DC-DC module is also connected in series with a set of transmission resistors to the positive terminal of the corresponding operational amplifier.

5. The current sharing circuit using operational amplifiers according to claim 1, characterized in that, The Vout output voltage of the main DC-DC module and the secondary DC-DC module is the voltage after inductance processing.

6. The current sharing circuit using operational amplifiers according to claim 4, characterized in that, The positive terminal of the operational amplifier is also connected to another set of transmission resistors, which are grounded.

7. The current sharing circuit using operational amplifiers according to claim 6, characterized in that, The power supply terminal of the operational amplifier is connected to another set of capacitors, which are grounded.

8. The current sharing circuit using operational amplifiers according to claim 5, characterized in that, Both the main DC-DC module and the secondary DC-DC module are composed of BUCK circuits.

9. The current sharing circuit using operational amplifiers according to claim 8, characterized in that, The main DC-DC module and the secondary DC-DC module are powered by the BCM.

10. The current sharing circuit using operational amplifiers according to claim 1, characterized in that, The operational amplifier is a differential amplifier.

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