Circuit and method for realizing current sharing through master-slave parallel connection

Abstract

The invention discloses a circuit and a method for realizing current sharing through master-slave parallel connection, and the method is characterized in that a master machine and a plurality of slave machines are connected in parallel, and are respectively connected to a current sharing control bus through an isolation chip, a TTL and differential mutual conversion unit and an information gating switch in sequence, thereby forming a parallel current sharing circuit; comprising a host issuing current reference circuit and a processing circuit after a slave receives a current reference signal from the host. After a plurality of instrument power supplies are connected in parallel, a user sets a master-slave parallel mode on a front panel of the power supplies and selects a master computer, and other computers are slave computers; when a plurality of power supplies work in parallel, the host issues a current reference signal to the current sharing control bus through the current reference generation circuit, and the slave outputs a corresponding current value according to the current reference signal issued by the host. One of a plurality of power supply modules can be randomly selected as a main module, the flexibility is high, the stability is good, and the power supply has the characteristics of simplicity in wiring and control, low transmission loss of control signals, difficulty in interference of the control signals, balanced output control of all the power supply modules and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of high-power power supply products, especially to a kind of circuit and method for realizing current sharing by master-slave parallel connection. BACKGROUND

[0002] With the development and application of modern power electronics technology and high-power switching power supply, high-power power supply products are also more and more widely used in aerospace and national defense, industrial site, automotive electronics, robots, numerical control processing, photovoltaic and other industries. However, with the increase of power level, the size of electrolytic capacitor and inductor, transformer and other devices required in the circuit will inevitably increase, resulting in the size of power supply products becoming larger and larger. In the development of power supply industry for decades, improving power density has become an indisputable trend, and this trend is expected to continue. However, in a limited space, it is impossible to realize more and more power conversion from the improvement of circuit design scheme alone, but also needs to rely on the progress of technology of capacitor, inductor, transformer and other related components. Therefore, in the case of being unable to improve the power of a given power supply, using multiple parallel connection to improve the total output power becomes a feasible solution.

[0003] At present, in the power supply industry, the common parallel current sharing schemes include output impedance method, average current method, peak current method, master-slave control method, etc.; among them, the main parallel connection scheme is mainly used in power supply and test power supply products, which is that the master sends control commands and given current reference values, and the slave accepts the corresponding commands and reference values and then outputs independently. In the traditional master-slave control method, the current reference signal of the master is directly connected to the first slave current control loop through the serial communication bus, and the first slave acts as the master of the second slave to continue to send reference signals to the third level in the same way. Since the reference signals of the previous and subsequent levels are not isolated, the reference signals of all power supplies are "commonly grounded", and when one of the power supplies is disturbed, it will affect the entire parallel system, and the stability and anti-interference performance are poor.

[0004] Prior art, parallel connection of power supply to realize current sharing:

[0005] The master and slave realize the issuance of reference signals and output signals through serial communication, thereby realizing parallel connection; the principle diagram of the scheme is shown in Figure 1

[0006] In this scheme, each power supply module sends voltage, current reference, On / Off signal, etc. to the next level through serial communication; the master can control the working mode of the slave, and can also read the working state and other measurement data of the slave, etc.

[0007] Disadvantages of the prior art, parallel connection of power supply to realize current sharing: ​

[0008] (1) the communication between each power module does not take signal isolation measures, when one of the power modules communication signal is disturbed, the whole parallel system will be affected, poor anti-interference.

[0009] (2) each power module does not take bus gating measures for current sharing control, when multiple power sources working in parallel mode want to work in other ways (single machine, multi-channel, networking), the parallel signal line must be removed to enter other corresponding working mode, poor flexibility.

[0010] Therefore, the present application is proposed. SUMMARY

[0011] The purpose of the present application is to provide a circuit and method for realizing current sharing by master-slave parallel connection, to solve the above technical problems in the prior art.

[0012] The purpose of the present application is achieved by the following technical solutions:

[0013] The circuit for realizing current sharing by master-slave parallel connection of the present application, the master and multiple slaves are connected in parallel, and are connected to the current sharing control bus through isolation chips, TTL and differential interconversion units, information gating switches in turn, to form a parallel current sharing circuit.

[0014] It includes a current reference circuit for the master to issue and a processing circuit for the slave to receive the current reference signal from the master.

[0015] The method for realizing current sharing by master-slave parallel connection of the above-mentioned circuit includes:

[0016] First, after multiple instrument power supplies are connected in parallel, the user sets the master-slave parallel mode in the front panel of the power supply and selects a master and other slaves.

[0017] Then, when multiple power supplies are working in parallel, the master issues a current reference signal to the current sharing control bus through the current reference generation circuit, and the slave outputs the corresponding current value according to the current reference signal issued by the master. During this process, the master works in CV mode and the other slaves work in CC mode.

[0018] Compared with the prior art, the circuit and method for realizing current sharing by master-slave parallel connection provided by the present application can arbitrarily select one of multiple power supplies as a master module, with strong flexibility, good stability, simple connection and control, low control signal transmission loss, control signal not easy to be disturbed, all power module output control balanced, etc. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The principle diagram of the prior art power supply parallel current sharing scheme.

[0020] Figure 2 Fig. 1 is a schematic diagram of a host issuing a current reference in an embodiment of the present application.

[0021] Figure 3 Fig. 2 is a general principle block diagram of an embodiment of the present application.

[0022] Figure 4 Fig. 3 is a schematic diagram of a processing circuit after a slave receives a current reference signal from a host in an embodiment of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application, which do not constitute a limitation of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0024] First, the terms possibly used in the present text are described as follows:

[0025] The terms “include”, “contain”, “have”, “possess” or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, including a technical feature element (such as raw materials, components, ingredients, carriers, dosage forms, materials, sizes, parts, components, mechanisms, devices, steps, processes, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or articles, etc.) should be interpreted as not only including the explicitly listed technical feature element, but also including other technical feature elements not explicitly listed in the art.

[0026] The term “consisting of” means excluding any technical feature element not explicitly listed. If this term is used in a claim, the term will make the claim closed, so that it does not contain technical feature elements other than the explicitly listed technical feature elements, except for conventional impurities related thereto. If the term only appears in a certain clause of the claim, it is only limited to the elements explicitly listed in that clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0027] The contents not described in detail in the embodiments of the present application belong to the prior art known to those skilled in the art. If the specific conditions are not specified in the embodiments of the present application, they are performed according to the conventional conditions in the art or the conditions recommended by the manufacturer. If the reagents or instruments used in the embodiments of the present application are not specified by the manufacturer, they are all conventional products that can be obtained by commercial purchase.

[0028] The circuit for realizing current sharing by master-slave parallel connection of the application comprises a master and a plurality of slaves which are connected to a current sharing control bus in parallel and are connected to the current sharing control bus through isolation chips, TTL and differential conversion units and information gating switches in sequence respectively, thereby forming a parallel current sharing circuit.

[0029] The current reference circuit issued by the master and the processing circuit after the slave receives the current reference signal from the master are included.

[0030] The current reference circuit issued by the master comprises:

[0031] The reference voltage VREF is connected to the inverting input terminal of the operational amplifier U1 through resistor R1 and is connected to the non-inverting input terminal of the operational amplifier U1 through resistor R2 and resistor R3; capacitor C1 is connected across the inverting input terminal and the output terminal of the operational amplifier U1.

[0032] The drain of MOS transistor Q1 is connected to the middle of resistor R2 and resistor R3, the gate is connected to the output pin of the operational amplifier U1 through resistor R4, and the source is connected to the collector of transistor Q2 through resistor R7.

[0033] The base of transistor Q2 is connected to the PWM signal pin of the MCU through resistor R8, the emitter of transistor Q2 is grounded, and resistor R9 is connected between the base and the emitter of transistor Q2.

[0034] Through the above connection, a triangular wave generating circuit is formed.

[0035] The processing circuit after the slave receives the current reference signal from the master comprises:

[0036] The current reference signal from the master enters the S pin of analog switch A1 after passing through the filter circuit composed of resistor R10 and capacitor C3; the GND pin of analog switch A1 is connected to GND, the VCC pin is connected to VCC, the B1 pin is connected to GND (low level), the B2 pin is connected to VREF2 (high level), the A pin is connected to the non-inverting input terminal of operational amplifier U3 through the second-order filter circuit composed of resistor R13, capacitor C4, resistor R14 and capacitor C5; resistor R11 and potentiometer RM1 are connected in series and are connected across the inverting input terminal and the output terminal of operational amplifier U3, one end of resistor R12 is connected to the inverting input terminal of operational amplifier U3, and the other end is grounded, thereby forming a proportional adjustable non-inverting proportional amplification circuit.

[0037] The output pin of operational amplifier U3 is connected to the input of the current loop of the slave.

[0038] The method for realizing current sharing by master-slave parallel connection of the above-mentioned circuit comprises:

[0039] Firstly, after multiple instrument power supplies are connected in parallel, a user sets master and slave parallel modes in front panels of the power supplies and selects a master, and the others are slaves;

[0040] After that, when multiple power supplies are connected in parallel, the master sends a current reference signal to a current control bus through a current reference generating circuit, and the slave outputs a corresponding current value according to the current reference signal sent by the master, in the process, the master works in a CV mode, and the other slaves work in a CC mode.

[0041] Firstly, the master MCU generates a PWM signal, and then a triangular wave is generated through a triangular wave generating circuit, the triangular wave is chopped to generate a reference PWM signal sent to the current control bus by comparing the triangular wave with a sampled current signal of the master;

[0042] Then, after the slave connected to the current control bus receives the reference signal from the master, the pulse width of the reference signal is introduced into a same-phase proportional amplification circuit as an input signal through an analog switch, and then the output signal of the same-phase proportional amplification circuit is sent to a current control loop of the slave.

[0043] As can be seen from the above, the circuit and method for realizing current sharing through master-slave parallel connection according to the embodiment of the application, the parallel connection mode described belongs to one of master-slave parallel connection modes, the reference signal is sent to a TTL-to-differential chip in the form of a PWM signal through an isolation chip, and is sent to a receiving circuit of a next slave in the form of a differential signal, so that the accuracy, stability and anti-interference of the reference signal are maximally ensured; when multiple power supplies are connected in parallel, one master module is set artificially, and all other modules output power by taking the reference sent by the master module as a reference; under this parallel connection mode, the master module works in a constant voltage source (CV) mode, and the remaining modules work in a constant current source (CC) mode, one of the multiple power supplies can be arbitrarily selected as the master module, the flexibility is high, the stability is good, and the parallel connection mode has the characteristics of simple connection and control, low control signal transmission loss, control signal not easy to be disturbed, balanced output control of all power supply modules and the like.

[0044] In order to more clearly show the technical solutions provided by the application and the technical effects generated, the following will describe the parallel connection mode provided by the embodiment of the application in detail with specific embodiments.

[0045] The technical problems to be solved by the application are:

[0046] (1) The communication stability of each power supply module when the power supply is connected in parallel is improved.

[0047] (2) By increasing a signal gating module, the power supply module connected to the current sharing bus can flexibly change the working mode without removing the communication line.

[0048] Embodiment 1:

[0049] like Figures 2 to 4 As shown:

[0050] First, after multiple instrument power supplies are connected in parallel, the user sets the master / slave parallel mode on the front panel of the power supply and selects one master (the others are slaves). When multiple power supplies work in parallel, the master first sends a current reference signal to the current sharing control bus through the current reference generation circuit. The slaves output the corresponding current value according to the current reference signal sent by the master (the master works in CV mode, and the other slaves work in CC mode). First, the master MCU generates a PWM signal, and then generates a triangular wave through the triangular wave generation circuit. The triangular wave is compared with the current signal sampled by the master and chopped to generate a reference PWM signal, which is sent to the current sharing control bus. After receiving the reference signal from the master, the slave connected to the current sharing control bus introduces its pulse width as an input signal into the non-inverting proportional amplifier circuit through an analog switch, and then sends the output signal of the non-inverting proportional amplifier circuit to the current control loop of the slave.

[0051] In this scheme, the circuit achieves parallel current sharing through a master-slave parallel connection.

[0052] Figure 2 The host computer sends the current reference; Figure 2 In this diagram, VREF is a reference voltage, connected to the inverting input of op-amp U1 via resistor R1, and connected to the non-inverting input via resistors R2 and R3. Capacitor C1 is connected between the inverting input and output of op-amp U1. The drain of MOSFET Q1 is connected between resistors R2 and R3, the gate is connected to the output pin of op-amp U1 via resistor R4, and the source is connected to the collector of transistor Q2 via resistor R7. The base of transistor Q2 is connected to the PWM signal pin of the MCU via resistor R8, the emitter of transistor Q2 is grounded, and resistor R9 is connected between the base and emitter of transistor Q2. Through the above connections, a triangular wave generator circuit is obtained. At this point, by adjusting the pulse width and frequency of the PWM signal emitted by the MCU, a triangular wave can be obtained at the source of MOSFET Q1 and introduced into the inverting input of op-amp U2. The inverting input of op-amp U2 is connected to the host current sampling signal through resistor R6. By comparing the triangular wave and the current sampling signal level, chopping is performed, and a reference PWM signal can be obtained at the output of op-amp U2. Depending on different current sampling values, PWM signals with different pulse widths can be obtained at the output of op-amp U2. Then, through a filter circuit composed of resistor R5 and capacitor C2, this PWM signal is sent to the current sharing control target line.

[0053] Figure 3 This is a block diagram illustrating the overall principle of this solution. Figure 3 The main unit current reference is connected to the current sharing control bus.

[0054] Figure 4 The processing circuit of the slave receiving the current reference signal from the host, Figure 4 The slave introduces the reference signal into the current control loop; the current reference signal from the host enters the S pin of analog switch A1 after passing through the filter circuit composed of resistor R10 and capacitor C3; the GND pin of analog switch A1 is connected to GND, the VCC pin is connected to VCC, the B1 pin is connected to GND (low level), the B2 pin is connected to VREF2 (high level), and the A pin is connected to the non-inverting input terminal of operational amplifier U3 through the second-order filter circuit composed of resistor R13, capacitor C4, resistor R14 and capacitor C5; resistor R11 and potentiometer RM1 are connected in series and are connected across the inverting input terminal and the output terminal of operational amplifier U3, one end of resistor R12 is connected to the inverting input terminal of operational amplifier U3, and the other end is connected to ground, thereby forming a proportional adjustable non-inverting proportional amplification circuit; the output pin of operational amplifier U3 is connected to the slave current loop input, and the effect of the host controlling the output current value of the slave is obtained.

[0055] The beneficial effects brought by the technical scheme of the application

[0056] (1) The host reference signal is given to the current sharing control bus in the form of isolated differential signal, which greatly improves the stability and anti-interference of the entire parallel system;

[0057] (2) The point-to-point communication mode is adopted, which ensures the signal synchronization compared with the traditional point-to-surface communication mode;

[0058] (3) Each power supply module adopts a signal gating mode, which can switch the working mode at any time and improves the use flexibility;

[0059] The circuit realizes the parallel connection of multiple power supplies through the point-to-point communication mode, and adopts multiple protection measures such as signal isolation, signal conversion and signal gating, which improves the stability and flexibility during parallel operation, and the key points of the technology are:

[0060] The reference signal is obtained by triangular wave chopping, and then the parallel connection or networking is realized through the signal isolation, signal conversion and signal gating.

[0061] The above description is merely preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions easily conceived by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of the present application is merely intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes the prior art known to those skilled in the art.

Claims

1. A circuit for current sharing by master-slave parallel connection, characterized in that, The host and the plurality of slaves are connected in parallel and are connected to a current sharing control bus through isolation chips, TTL and differential conversion units and information gating switches in sequence respectively to form a parallel current sharing circuit. The current reference circuit includes a host current reference circuit and a slave processing circuit after receiving the current reference signal from the host.

2. The circuit and method for current sharing by master-slave parallel connection according to claim 1, characterized in that, The host current reference circuit includes: The reference voltage VREF is connected to the inverting input terminal of the operational amplifier U1 through resistor R1 and to the non-inverting input terminal of the operational amplifier U1 through resistors R2 and R3; capacitor C1 is connected across the inverting input terminal and the output terminal of the operational amplifier U1; The drain of the MOS transistor Q1 is connected to the middle of resistors R2 and R3, the gate is connected to the output pin of the operational amplifier U1 through resistor R4, and the source is connected to the collector of the transistor Q2 through resistor R7; The base of the transistor Q2 is connected to the PWM signal pin of the host MCU through resistor R8, the emitter is grounded, and resistor R9 is connected between the base and the emitter of the transistor Q2. Through the above connection, a triangular wave generating circuit is formed.

3. The circuit and method for current sharing by master-slave parallel connection according to claim 2, characterized in that, The slave processing circuit after receiving the current reference signal from the host includes: The current reference signal from the host enters the S pin of the analog switch A1 after passing through the filter circuit composed of resistor R10 and capacitor C3; the GND pin of the analog switch A1 is connected to GND, the VCC pin is connected to VCC, the B1 pin is connected to GND low level, the B2 pin is connected to VREF2 high level, the A pin is connected to the non-inverting input terminal of the operational amplifier U3 through the second-order filter circuit composed of resistor R13, capacitor C4, resistor R14 and capacitor C5; resistor R11 and potentiometer RM1 are connected in series and connected across the inverting input terminal and the output terminal of the operational amplifier U3, resistor R12 is connected to the inverting input terminal of the operational amplifier U3 at one end and grounded at the other end, thereby forming a proportional adjustable non-inverting proportional amplification circuit; The output pin of the operational amplifier U3 is connected to the input of the slave current loop.

4. A method for achieving current sharing by master-slave parallel connection of the circuit according to claim 1, 2 or 3, characterized in that, It includes: Firstly, after a plurality of instrument power supplies are connected in parallel, the user sets the master-slave parallel mode on the front panel of the power supply and selects a host, and the others are slaves; Then, when the plurality of power supplies are working in parallel, the host sends a current reference signal to the current sharing control bus through the current reference generating circuit, and the slave outputs the corresponding current value according to the current reference signal sent by the host. During this process, the host works in CV mode and the other slaves work in CC mode.

5. The method of claim 4, wherein: Firstly, the host MCU generates a PWM signal, and then generates a triangular wave through a triangular wave generating circuit, and the triangular wave is compared with the sampled current signal to generate a reference PWM signal which is sent to the current sharing control bus. Then, the slave machine connected to the current sharing control bus receives the reference signal from the master machine, and through an analog switch, the pulse width of the reference signal is introduced into the in-phase proportional amplification circuit as an input signal, and the output signal of the in-phase proportional amplification circuit is sent to the current control loop of the slave machine.

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