A DC power supply parallel system and current sharing control method

Abstract

The present invention belongs to the technical field of direct current power supplies and parallel connection thereof, and provides a direct current power supply parallel connection system and a current sharing control method, comprising a host and multiple slaves, wherein the host and the slaves are connected in parallel via a current sharing signal line, wherein the current sharing signal line comprises two signal lines, Share+ and Share‑, wherein the grounding ends of the host and the slaves are both connected to the Share‑ signal line, and the host and the slaves each comprise a Master end and a S l ave end, wherein the Master of the host is connected to the S l ave ends of all the slaves via the Share+ signal line to form a parallel connection system.

Description

Technical Field

[0001] The present invention belongs to the technical field of direct current power supplies and parallel connection thereof, and in particular relates to a direct current power supply parallel connection system and a current sharing control method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] In recent years, DC power conversion technology has been changing with each passing day, especially wide bandgap devices have greatly promoted the development of DC power supplies, and DC power supplies are developing towards modularization, high efficiency, high power density and high dynamic response. Modular power supplies can realize the parallel connection of multiple small and medium power supplies to jointly bear high power output. Compared with traditional centralized power supply systems, the number of parallel power supplies can be changed to meet the power requirements of different loads, and it has the advantages of small stress on each module power supply, high power density, high efficiency and fast response. Due to the inconsistency of each unit module, if the module power supply is directly connected in parallel, it will bear an unbalanced load, resulting in some power modules shortening their life due to excessively large output currents, or even failures, so it is necessary to use current balancing technology to balance the output currents of each power module.

[0004] Common current sharing methods include master-slave method, average value method, maximum current method, and output voltage droop method;

[0005] 1. The master-slave current sharing method is to automatically use the current on the host module power supply in the control bus as the single-channel current reference of the entire power supply system, and the other module power supplies use it as a reference to adjust their own output current;

[0006] 2. The average current method is to divide the sum of the output currents of all parallel power supply devices by the number of all parallel power supply devices. The average value is calculated as the single-channel current benchmark of the entire power supply system. All module power supplies use it as a benchmark to adjust their own output currents.

[0007] 3. The maximum current method is to automatically use the current on the module power supply with the largest output current in the control bus as the single-channel current reference of the entire power supply system, and the remaining module power supplies use it as a reference to adjust their own output current.

[0008] 4. Output voltage droop method: As the output current increases, the output voltage is gradually reduced, so that the output current of this module in the parallel system is relatively reduced to achieve current sharing;

[0009] Among the many current balancing solutions, the most commonly used one is the master-slave current balancing solution. The traditional master-slave current balancing method is divided into a master and a slave. The control circuits of the master and the slave are different. Two different types of equipment are required to build a parallel system, which is not conducive to the standardized production of products. When the slave current balancing line is disconnected in a running system, the output voltage and current of the slave are uncontrolled, which affects the operation of the entire system and makes it impossible to automatically exit the system in case of a fault. Summary of the invention

[0010] In order to solve at least one technical problem existing in the above-mentioned background technology, a first aspect of the present disclosure provides a DC power parallel system, which has the effect of only needing two signal lines, having a simple current balancing circuit topology and high reliability.

[0011] In order to achieve the above object, the present invention adopts the following technical solution:

[0012] A DC power parallel system includes a host and multiple slaves, characterized in that the host and the slaves are connected in parallel via a current sharing signal line, the current sharing signal line includes two signal lines, Share+ and Share-, the ground terminals of the host and the slaves are both connected to the Share- signal line, the host and the slaves each include a Master terminal and a Slave terminal, the Master of the host is connected to the Slave terminals of all the slaves via the Share+ signal line to form a parallel system.

[0013] In order to solve the above problems, the second aspect of the present invention provides a DC power supply current sharing control method, in which all parallel module power supplies share an output voltage outer loop, the load adjustment rate is consistent with that of a single module power supply, and the output voltage accuracy is high; no circulating current is formed between the parallel system module power supplies, and the system stability is high.

[0014] In order to achieve the above object, the present invention adopts the following technical solution:

[0015] A DC power supply current sharing control method, comprising:

[0016] The master and slave machines are configured by switching relays;

[0017] The master and slave devices achieve terminal current balance through module power control circuit control.

[0018] A further technical solution is that the master and slave machines are configured by switching relays, specifically:

[0019] When configured as a host, the Share+ signal line is connected to the Master end of the module control power circuit through a relay, the Slave end is left floating, and the Share- signal line is connected to GND;

[0020] When configured as a slave, the Share+ signal line is connected to the Slave end of the module control power circuit via a relay, the Master end is left floating, and the Share- signal line is connected to GND.

[0021] According to a further technical solution, the module power control circuit includes a plurality of operational amplifiers, each of which includes a non-inverting input terminal, a reverse input terminal and an output terminal.

[0022] A further technical solution is that the first operational amplifier includes a non-inverting input terminal and a reverse input terminal, the input of the non-inverting input terminal is a voltage obtained by combining the voltage feedback obtained by sampling the input voltage sampling circuit with a given voltage; the reverse input terminal is connected to GND through a tenth resistor, and at the same time, the reverse input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier through a first resistor and a second resistor, and the output terminal of the first operational amplifier is connected to the Slave terminal through the first resistor.

[0023] A further technical solution is that the Slave end is connected to the same-direction input end of the third operational amplifier through a third resistor, the reverse input end of the third operational amplifier is connected to GND through an eighth resistor, and at the same time, the reverse input end of the third operational amplifier is connected to the output end of the third operational amplifier after passing through a fourth resistor and a fifth resistor. The output current of the output end of the third operational amplifier through the fifth resistor is used as a current given, and the current feedback obtained by sampling with the current sampling circuit is sent to the current loop, and after calculation by the current loop, it is sent to the PWM chopping module to output a PWM signal.

[0024] According to a further technical solution, the PWM signal is used to drive the main circuit of the module power supply.

[0025] A further technical solution is that the output end of the third operational amplifier is connected to the same-direction input end of the second operational amplifier through the fifth resistor, the reverse input end of the second operational amplifier is connected to GND through the ninth resistor, and the reverse input end of the second operational amplifier is connected to the output end of the second operational amplifier through the sixth resistor and the seventh resistor, and the output end of the second operational amplifier is connected to the Master end through the seventh resistor.

[0026] A further technical solution is that when the current-sharing line is disconnected or fails, the potential of the slave end is controlled by the slave voltage loop through the first operational amplifier, the first resistor, the second resistor, and the tenth resistor. The slave output voltage and current will not be out of control, thereby achieving automatic exit when a slave current-sharing bus failure occurs.

[0027] According to a further technical solution, all parallel power supplies share an output voltage outer loop.

[0028] The beneficial effects of the present invention are:

[0029] (1) The present disclosure switches the master-slave configuration through relays, and can quickly complete the system configuration without changing the hardware circuit of the entire system; when one of the power modules fails to work, within the full load output range, the main power system will redistribute the output current so that the power supply of the module continues to work normally without being affected.

[0030] (2) In view of the shortcomings of the average current method and the maximum current method, which require the collection of the current of all module power supplies and have complex topology and poor reliability, the current sharing bus disclosed in the present invention only requires two signal lines, and the current sharing circuit topology is simple and has high reliability.

[0031] (3) In order to address the defect that the output voltage droop method cannot take into account both the current balancing effect and the load regulation rate, all parallel module power supplies disclosed in the present invention share an output voltage outer loop, the load regulation rate is consistent with that of a single module power supply, and the output voltage accuracy is high; no circulating current will be formed between the parallel system module power supplies, and the system stability is high.

[0032] (4) When the current-sharing bus disclosed in the present invention is disconnected due to a fault, the slave module automatically exits bus control and switches to slave voltage control, so that the parallel system can increase or decrease the number of module power slaves without shutting down the system, and realize hot swapping of module power supplies.

[0033] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0035] Figure 1 It is a schematic diagram of the overall structure of the DC power supply current sharing control system provided by this embodiment of the present disclosure;

[0036] Figure 2 is a circuit diagram of a module power supply control circuit provided by this embodiment of the present disclosure;

[0037] Figure 3 It is the main circuit diagram of the module power supply provided in this embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0041] In the present invention, the directions or positional relationships indicated by terms such as "upper" and "lower" are based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0042] In the present invention, terms such as "connected" and "connection" should be understood in a broad sense, indicating that the connection can be fixed, integral or detachable; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meaning of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0043] Example 1

[0044] like Figure 1 As shown, this embodiment provides a DC power parallel system, including a host and multiple slaves, the host and the slaves are connected in parallel through a current sharing signal line, the current sharing signal line includes two signal lines Share+ and Share-, the ground ends of the host and the slaves are connected to the Share- signal line, the host and the slaves include a Master end and a Slave end, the Master of the host is connected to the Slave ends of all slaves through the Share+ signal line to form a parallel system.

[0045] In the above parallel system, the current sharing bus only needs two signal lines, the current sharing circuit topology is simple and the reliability is high;

[0046] In a specific implementation, the Master end of the host is connected to the Slave ends of all slaves, and the slave voltage reference Vref is set to 0. At this time, the potential of the Slave end of the slave is controlled by the Master end of the host, so that the slave follows the output current of the host to achieve current sharing.

[0047] Example 2

[0048] This embodiment provides a DC power supply current sharing control method, which is applied to the DC power supply parallel system in the above embodiment 1. The method includes:

[0049] The master and slave machines are configured by switching relays;

[0050] The master and slave devices achieve terminal current balance through module power control circuit control.

[0051] The specific contents of the switching of the configuration master and slave are as follows:

[0052] When configured as a host, Share+ is connected to the Master end of the module control power circuit via a relay, the Slave end is left floating, and Share- is connected to GND;

[0053] When configured as a slave, Share+ is connected to the Slave end of the module control power circuit via a relay, the Master end is left floating, and Share- is connected to GND;

[0054] like Figure 2 As shown, in a specific implementation, the block power control circuit includes a plurality of operational amplifiers, each of which includes a non-inverting input terminal, an inverting input terminal, and an output terminal.

[0055] The voltage sampling circuit samples and obtains the voltage feedback Vfb, which is combined with the given voltage Vref and input into the non-inverting input terminal of the first operational amplifier U1;

[0056] The inverting input terminal of the first operational amplifier U1 is connected to GND through the resistor R10, and the inverting input terminal of the first operational amplifier U1 is connected to the output terminal of the first operational amplifier U1 through the resistor R1 and the resistor R2, and the output terminal of the first operational amplifier U1 is connected to the Slave terminal through the resistor R1;

[0057] The Slave end is connected to the same-direction input end of the third operational amplifier U3 through the resistor R3, and the reverse input end of the third operational amplifier U3 is connected to GND through the resistor R8. At the same time, the reverse input end of the third operational amplifier U3 is connected to the output end of the third operational amplifier U3 of the operational amplifier U3 after passing through the resistors R4 and R5. The output end of the third operational amplifier U3 outputs current as the current given Iref through the resistor R5, and the current feedback Ifb obtained by sampling with the current sampling circuit is sent to the current loop, and after calculation by the current loop, it is sent to the PWM chopping module to output the PWM signal; the output PWM signal is used to drive the main circuit of the module power supply.

[0058] At the same time, the output end of the third operational amplifier U3 is connected to the same-direction input end of the second operational amplifier U2 through the resistor R5, the reverse input end of the second operational amplifier U2 is connected to GND through the resistor R9, and the reverse input end of the second operational amplifier U2 is connected to the output end of the second operational amplifier U2 through the resistor R6 and the resistor R7, and the output end of the second operational amplifier U2 is connected to the Master end through the resistor R7.

[0059] When the current sharing line is disconnected or fails, the potential of the slave end is controlled by the slave voltage loop through the operational amplifier U1, resistor R1, resistor R2, and resistor R10. The slave output voltage and current will not be out of control, and the slave will automatically exit when a current sharing bus failure occurs, thereby protecting the safety of the entire system.

[0060] All parallel module power supplies share the output voltage outer loop, the load regulation rate is consistent with that of a single module power supply, and the output voltage accuracy is high; no circulating current will be formed between the parallel system module power supplies, and the system stability is high.

[0061] Figure 3 This is the main circuit diagram of the module power supply, such as Figure 3 As shown, the positive electrode of capacitor C1 is connected to the drain terminal of MOS tube S1, the source terminal of MOS tube S1 is connected to the drain terminal of MOS tube S2, the source terminal of MOS tube S2 is connected to the negative electrode of C1, the drain terminal of MOS tube S2 is connected to terminal 1 of inductor L1, terminal 2 of inductor L1 is connected to the positive electrode of capacitor C2, the source terminal of MOS tube S2 is connected to terminal 1 of R1, and terminal 2 of R1 is connected to the negative electrode of C2; wherein R1 is a current sampling resistor.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A DC power parallel system, comprising a host and a plurality of slaves, characterized in that: The host and the slave are connected in parallel via a current sharing signal line, the current sharing signal line includes two signal lines, Share+ and Share-, the ground terminals of the host and the slave are connected to the Share- signal line, the host and the slave each include a Master terminal and a Slave terminal, the Master of the host is connected to the Slave terminals of all the slaves via the Share+ signal line, forming a parallel system; In a parallel system, the current sharing bus only requires two signal wires; The master and slave machines are configured by switching relays, specifically: When configured as a host, the Share+ signal line is connected to the Master end of the module control power circuit through a relay, the Slave end is left floating, and the Share- signal line is connected to GND; When configured as a slave, the Share+ signal line is connected to the Slave end of the module control power circuit through a relay, the Master end is left floating, and the Share- signal line is connected to GND; The first operational amplifier includes a non-inverting input terminal and a reverse input terminal, wherein the input of the non-inverting input terminal is a voltage obtained by combining a voltage feedback obtained by sampling an input voltage sampling circuit with a given voltage; the reverse input terminal is connected to GND through a tenth resistor, and the reverse input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier through a first resistor and a second resistor, and the output terminal of the first operational amplifier is connected to the Slave terminal through the first resistor; When the current sharing line is disconnected or fails, the potential of the slave end is controlled by the slave voltage loop through the first operational amplifier, the first resistor, the second resistor, and the tenth resistor. The slave output voltage and current will not be out of control, and the slave will automatically exit when a current sharing bus failure occurs.

2. A DC power supply current sharing control method, using the DC power supply parallel system according to claim 1, the method comprising: The master and slave machines are configured by switching relays; The master and slave machines realize terminal current balancing through module power supply control circuit control; In a parallel system, the current sharing bus only requires two signal wires; The master and slave machines are configured by switching relays, specifically: When configured as a host, the Share+ signal line is connected to the Master end of the module control power circuit through a relay, the Slave end is left floating, and the Share- signal line is connected to GND; When configured as a slave, the Share+ signal line is connected to the Slave end of the module control power circuit through a relay, the Master end is left floating, and the Share- signal line is connected to GND; The first operational amplifier includes a non-inverting input terminal and a reverse input terminal, wherein the input of the non-inverting input terminal is a voltage obtained by combining a voltage feedback obtained by sampling an input voltage sampling circuit with a given voltage; the reverse input terminal is connected to GND through a tenth resistor, and the reverse input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier through a first resistor and a second resistor, and the output terminal of the first operational amplifier is connected to the Slave terminal through the first resistor; When the current sharing line is disconnected or fails, the potential of the slave end is controlled by the slave voltage loop through the first operational amplifier, the first resistor, the second resistor, and the tenth resistor. The slave output voltage and current will not be out of control, and the slave will automatically exit when a current sharing bus failure occurs.

3. A DC power supply current sharing control method as claimed in claim 2, characterized in that: The module power control circuit includes a plurality of operational amplifiers, each of which includes a non-inverting input terminal, a reverse input terminal and an output terminal.

4. A DC power supply current sharing control method as claimed in claim 2, characterized in that: The slave end is connected to the same-direction input end of the third operational amplifier through the third resistor, the reverse input end of the third operational amplifier is connected to the GND through the eighth resistor, and the reverse input end of the third operational amplifier is connected to the output end of the third operational amplifier through the fourth resistor and the fifth resistor. The output current of the output end of the third operational amplifier through the fifth resistor is used as the current given, and the current sampling circuit samples the current to obtain the current feedback and send it to the current loop, and after the current loop is calculated, it is sent to the PWM chopping module to output the PWM signal.

5. A DC power supply current sharing control method as claimed in claim 4, characterized in that: The PWM signal is used to drive the main circuit of the module power supply.

6. A DC power supply current sharing control method as claimed in claim 4, characterized in that: The output end of the third operational amplifier is connected to the same-direction input end of the second operational amplifier through the fifth resistor, the reverse input end of the second operational amplifier is connected to GND through the ninth resistor, and the reverse input end of the second operational amplifier is connected to the output end of the second operational amplifier through the sixth resistor and the seventh resistor, and the output end of the second operational amplifier is connected to the Master end through the seventh resistor.

7. A DC power supply current sharing control method as claimed in claim 2, characterized in that: All paralleled power supplies share the output voltage outer loop.

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