A UPS parallel circulating current suppression circuit

Abstract

This utility model discloses a UPS parallel circulating current suppression circuit, belonging to the field of power supply technology. The circuit includes: multiple UPS units connected in parallel, a circulating current suppression control unit, and multiple acquisition units. Each UPS module's output terminal is connected to one acquisition unit. Each acquisition unit includes: an isolated current acquisition module for isolating and acquiring the UPS module's output current, an isolated voltage acquisition module for isolating and acquiring the UPS module's output voltage, and an analog-to-digital converter (ADC). The output terminals of the isolated current acquisition module and the isolated voltage acquisition module are both connected to the input terminal of the ADC. The output terminal of the ADC is connected to the input terminal of the circulating current suppression control unit. The control output terminal of the circulating current suppression control unit is connected to the controlled terminal of each UPS unit. This utility model can reduce noise interference, ensure the authenticity of the sampled signal, and improve the reliability of circulating current suppression.

Description

Technical Field

[0001] This utility model belongs to the field of power supply technology, specifically relating to a UPS parallel circulating current suppression circuit. Background Technology

[0002] In a parallel UPS (Uninterruptible Power Supply) system, circulating current suppression is one of the core technologies to ensure stable system operation. Due to slight differences in the output voltage, phase, or impedance of each module, a circulating current path can be formed, leading to uneven power distribution between modules, increased losses, and even equipment damage.

[0003] To suppress circulating current, the output current of each module needs to be collected in real time and the difference needs to be calculated. However, there is a potential difference between the high-power side and the low-voltage control side. Direct sampling can easily introduce common-mode interference and high-voltage risks, which will reduce the reliability of circulating current suppression. Utility Model Content

[0004] The purpose of this invention is to provide a UPS parallel circulating current suppression circuit to solve the problem that direct sampling can easily introduce common-mode interference and high voltage risk due to the potential difference between the high-power side and the low-voltage control side, which would reduce the reliability of circulating current suppression.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a UPS parallel circulating current suppression circuit, the circuit comprising: multiple UPS units connected in parallel, a circulating current suppression control unit, and multiple acquisition units; each UPS module's output terminal is connected to an acquisition unit;

[0006] Each acquisition unit includes: an isolated current acquisition module for isolated acquisition of the output current of the UPS module, an isolated voltage acquisition module for isolated acquisition of the output voltage of the UPS module, and an analog-to-digital conversion module. The output terminals of the isolated current acquisition module and the isolated voltage acquisition module are both connected to the input terminal of the analog-to-digital conversion module. The output terminal of the analog-to-digital conversion module is connected to the input terminal of the circulating current suppression control unit. The control output terminal of the circulating current suppression control unit is connected to the controlled terminal of each UPS unit.

[0007] Preferably, each UPS unit includes a rectifier, a battery, and an inverter. The power output terminal of the rectifier is connected to the power input terminal of the inverter and the power terminal of the battery, respectively. The power terminal of the battery is also connected to the power input terminal of the inverter.

[0008] Preferably, the isolated voltage acquisition module includes: sampling resistor R1, sampling resistor R2, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, capacitor C11, isolator U11, bidirectional diode D11, amplifier U12, and amplifier U13.

[0009] The first end of the sampling resistor R1 is connected to the first end of resistor R11 and the first end of capacitor C11 respectively. The second end of resistor R11 is connected to the first end of the input side of isolator U11. The first end of the sampling resistor R2 is connected to the first end of resistor R12 and the second end of capacitor C11 respectively. The second end of resistor R12 is connected to the second end of the input side of isolator U11.

[0010] The first terminal of the output side of the isolator U11 is connected to the first terminal of the bidirectional diode D11 and the non-inverting input terminal of the amplifier U12, respectively. The second terminal of the output side of the isolator U11 is connected to the second terminal of the bidirectional diode D11, the inverting input terminal of the amplifier U12 and the first terminal of the resistor R13, respectively.

[0011] The output terminal of the amplifier U12 is connected to the second terminal of resistor R13 and the first terminal of resistor R15 respectively. The second terminal of resistor R15 is connected to the non-inverting input terminal of amplifier U13 and the first terminal of resistor R14 respectively. The second terminal of resistor R14 is connected to the power supply.

[0012] The output terminal of the amplifier U13 is connected to the first terminal of the resistor R16, and the second terminal of the resistor R16 is connected to the inverting input terminal of the amplifier U13; the output terminal of the amplifier U13 is used as the output terminal of the isolated voltage acquisition module and connected to the input terminal of the analog-to-digital conversion module.

[0013] Preferably, both the sampling resistor R1 and the sampling resistor R2 comprise multiple resistors connected in series.

[0014] Preferably, the isolated current acquisition module includes: a current sensor U20, resistors R21, R22, R23, R24, R25, and R26, an isolator U21, a bidirectional diode D21, an amplifier U22, and an amplifier U23.

[0015] The output terminal of the current sensor U20 is connected to the first terminal of resistor R21 and the first terminal of resistor R22 respectively. The second terminal of resistor R22 is connected to the first terminal of the input side of isolator U21. The second terminal of resistor R21 is connected to the second terminal of the input side of isolator U21.

[0016] The first terminal of the output side of the isolator U21 is connected to the first terminal of the bidirectional diode D21 and the non-inverting input terminal of the amplifier U22, respectively. The second terminal of the output side of the isolator U21 is connected to the second terminal of the bidirectional diode D21, the inverting input terminal of the amplifier U22, and the first terminal of the resistor R23, respectively.

[0017] The output terminal of the amplifier U22 is connected to the second terminal of resistor R23 and the first terminal of resistor R25 respectively. The second terminal of resistor R25 is connected to the non-inverting input terminal of amplifier U23 and the first terminal of resistor R24 ​​respectively. The second terminal of resistor R24 ​​is connected to the power supply.

[0018] The output terminal of the amplifier U23 is connected to the first terminal of the resistor R26, and the second terminal of the resistor R26 is connected to the inverting input terminal of the amplifier U23; the output terminal of the amplifier U23 is used as the output terminal of the isolated current acquisition module and connected to the input terminal of the analog-to-digital conversion module.

[0019] Preferably, it further includes an AC bus, which is used to connect the load, and the output terminal of each UPS unit is connected to the AC bus.

[0020] Preferably, the circulating current suppression control unit includes: a controller and a PWM modulator. The PWM modulator is connected to the controller, with the I / O port of the controller serving as the input terminal of the circulating current suppression control unit and connected to the output terminal of the analog-to-digital conversion module. The PWM output port of the PWM modulator serves as the control output terminal of the circulating current suppression control unit and is connected to the controlled terminal of each UPS unit.

[0021] Preferably, the number of UPS units is 2 to 4.

[0022] The beneficial effects of this utility model are:

[0023] The acquisition unit of this utility model consists of an isolated current acquisition module and an isolated voltage acquisition module. The isolated current acquisition module is used to isolate and acquire the output current of the UPS module, and the isolated voltage acquisition module is used to isolate and acquire the output voltage of the UPS module. This can reduce noise interference, ensure the authenticity of the sampled signal, and improve the reliability of circulating current suppression. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 This is a block diagram of a UPS parallel circulating current suppression circuit provided in one embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of an isolated voltage acquisition module provided in one embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of an isolated current acquisition module provided in one embodiment of this utility model. Detailed Implementation

[0028] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the present utility model will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is used to help understand this utility model, but does not constitute a limitation on this utility model.

[0029] Example 1

[0030] Figure 1 This is a block diagram of a UPS parallel circulating current suppression circuit provided in one embodiment of this utility model. Figure 1 As shown, this embodiment provides a UPS parallel circulating current suppression circuit, which includes: multiple UPS units connected in parallel, a circulating current suppression control unit, multiple acquisition units, and an AC bus; each UPS module's output terminal is connected to an acquisition unit.

[0031] In this embodiment, the number of data acquisition units corresponds one-to-one with the number of UPS units. The number of UPS units is 2 to 4, preferably 3 UPS units, so there are also 3 corresponding data acquisition units.

[0032] In this embodiment, the AC bus is used to connect the load, and the output terminal of each UPS unit is connected to the AC bus.

[0033] Each acquisition unit includes: an isolated current acquisition module for isolated acquisition of the output current of the UPS module, an isolated voltage acquisition module for isolated acquisition of the output voltage of the UPS module, and an analog-to-digital conversion module. The output terminals of the isolated current acquisition module and the isolated voltage acquisition module are both connected to the input terminal of the analog-to-digital conversion module. The output terminal of the analog-to-digital conversion module is connected to the input terminal of the circulating current suppression control unit. The control output terminal of the circulating current suppression control unit is connected to the controlled terminal of each UPS unit.

[0034] In this embodiment, each UPS unit includes a rectifier, a battery, and an inverter. The power output terminal of the rectifier is connected to the power input terminal of the inverter and the power terminal of the battery, respectively. The power terminal of the battery is also connected to the power input terminal of the inverter. The controlled terminal of the inverter is used as the controlled terminal of the UPS unit and is connected to the control output terminal of the circulating current suppression control unit.

[0035] The rectifier converts the input AC power to DC power, while the inverter converts the input DC power to AC power. The inverter is controlled by a circulating current suppression control unit. Both the rectifier and inverter are conventional devices in this field, and their specific circuit structures are not detailed in this embodiment. When charging the UPS unit, the inverter does not operate; the rectifier is connected to the mains power, converting AC power to DC power and then using the DC power to charge the battery. When the UPS unit is needed as a power source, the inverter is controlled to start operating, converting the DC power output from the battery to AC power. The AC power output from the inverter provides operating power to the load through the AC bus. When multiple UPS units need to provide power to the load simultaneously, the inverters of multiple UPS units are controlled to start operating, providing operating power to the load.

[0036] In this embodiment, the circulating current suppression control unit includes a controller and a PWM modulator. The PWM modulator is connected to the controller, and the I / O port of the controller is used as the input terminal of the circulating current suppression control unit and connected to the output terminal of the analog-to-digital conversion module. The PWM output port of the PWM modulator is used as the control output terminal of the circulating current suppression control unit and connected to the controlled terminal of each UPS unit.

[0037] The controller can be an STM32 series microcontroller or a PLC (programmable logic controller), and the PWM modulator is used to output PWM modulation signals to adjust the amplitude and phase of the inverter's output voltage.

[0038] Therefore, when multiple UPS units simultaneously supply power to the load, circulating current will occur. To suppress circulating current, it is necessary to collect the voltage and current output of each UPS unit. Thus, the isolated current acquisition module transmits the collected current signal to the analog-to-digital converter (ADC). The current signal collected by the isolated current acquisition module is an analog signal, which is converted into a digital signal by the ADC and then sent to the circulating current suppression control unit. Similarly, the isolated voltage acquisition module transmits the collected voltage signal to the ADC. The voltage signal collected by the isolated voltage acquisition module is an analog signal, which is converted into a digital signal by the ADC and then sent to the circulating current suppression control unit. After receiving the voltage and current, the circulating current control unit generates corresponding control commands based on existing control algorithms, such as PID or virtual impedance control, to control the inverters and dynamically adjust the output voltage amplitude and phase of each inverter to force them to remain consistent, thereby reducing circulating current caused by voltage differences.

[0039] In this embodiment, the isolated current acquisition module and the isolated voltage acquisition module acquire the output current and output voltage of the UPS module in an isolated manner. Therefore, the isolated current acquisition module and the isolated voltage acquisition module can reduce noise interference, ensure the authenticity of the sampled signal, and improve the reliability of circulating current suppression.

[0040] Example 2

[0041] Based on Example 1, such as Figure 2 As shown, the isolated voltage acquisition module in this embodiment includes: sampling resistor R1, sampling resistor R2, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, capacitor C11, isolator U11, bidirectional diode D11, amplifier U12, and amplifier U13.

[0042] The first end of the sampling resistor R1 is connected to the first end of resistor R11 and the first end of capacitor C11 respectively. The second end of resistor R11 is connected to the first end of the input side of isolator U11. The first end of the sampling resistor R2 is connected to the first end of resistor R12 and the second end of capacitor C11 respectively. The second end of resistor R12 is connected to the second end of the input side of isolator U11.

[0043] The first terminal of the output side of the isolator U11 is connected to the first terminal of the bidirectional diode D11 and the non-inverting input terminal of the amplifier U12, respectively. The second terminal of the output side of the isolator U11 is connected to the second terminal of the bidirectional diode D11, the inverting input terminal of the amplifier U12 and the first terminal of the resistor R13, respectively.

[0044] The output terminal of the amplifier U12 is connected to the second terminal of resistor R13 and the first terminal of resistor R15, respectively. The second terminal of resistor R15 is connected to the non-inverting input terminal of amplifier U13 and the first terminal of resistor R14, respectively. The second terminal of resistor R14 is connected to a power supply, which is a 3.3V power supply.

[0045] The output terminal of the amplifier U13 is connected to the first terminal of the resistor R16, and the second terminal of the resistor R16 is connected to the inverting input terminal of the amplifier U13; the output terminal of the amplifier U13 is used as the output terminal of the isolated voltage acquisition module and connected to the input terminal of the analog-to-digital conversion module.

[0046] In this embodiment, the second end of the sampling resistor R1 is used as the positive terminal, and the second end of the sampling resistor R2 is used as the negative terminal, which are respectively connected to the output terminals (positive and negative terminals) of the UPS module; the isolator U11 is a current transformer, model CT101, and the amplifiers U12 and U13 are both model NCS2001SN2T1G.

[0047] The acquisition principle of the isolated voltage acquisition module in this embodiment is as follows: the current and voltage signals output by the inverter are linearly converted into low current signals through sampling resistors R1 and R2. The low current signals are then transmitted to the secondary side weak current detection terminal through the current transformer. The output of the current transformer is converted into AC voltage signals through sampling resistor R13 and amplifier U12 on the weak current side. The AC voltage signals are boosted and adjusted by resistors R14, R15, and R16 and amplifier U13 before being sent to the analog-to-digital conversion module.

[0048] In this embodiment, the voltage acquisition module utilizes isolator U11 to electrically isolate the high-voltage end from the low-voltage detection end, ensuring that the low-voltage detection end is not subject to electromagnetic interference from the high-voltage electric field. In this embodiment, capacitor C11, resistors R11 and R12 in the voltage acquisition module form an RC parallel filter, which can smooth the input voltage of isolator U11 and eliminate interference signals. Amplifiers U12 and U13 in the voltage acquisition module of this embodiment can increase the load-carrying capacity of the entire conversion circuit.

[0049] As a further optimization of this embodiment, both sampling resistor R1 and sampling resistor R2 include multiple resistors connected in series. The resistance value of each resistor in sampling resistor R1 is the same. Therefore, by connecting multiple resistors in series, this embodiment can significantly improve the voltage withstand capability of the entire resistor network, thereby ensuring the safety and reliability of the voltage acquisition circuit and meeting the requirements of high-precision detection. Therefore, the isolated voltage acquisition module of this embodiment has the advantages of strong anti-interference capability, strong load-bearing capacity, and high reliability.

[0050] Example 3

[0051] Based on Example 2, such as Figure 3 As shown, the isolated current acquisition module in this embodiment includes: current sensor U20, resistor R21, resistor R22, resistor R23, resistor R24, resistor R25, resistor R26, isolator U21, bidirectional diode D21, amplifier U22, and amplifier U23.

[0052] The output terminal of the current sensor U20 is connected to the first terminal of resistor R21 and the first terminal of resistor R22 respectively. The second terminal of resistor R22 is connected to the first terminal of the input side of isolator U21. The second terminal of resistor R21 is connected to the second terminal of the input side of isolator U21.

[0053] The first terminal of the output side of the isolator U21 is connected to the first terminal of the bidirectional diode D21 and the non-inverting input terminal of the amplifier U22, respectively. The second terminal of the output side of the isolator U21 is connected to the second terminal of the bidirectional diode D21, the inverting input terminal of the amplifier U22, and the first terminal of the resistor R23, respectively.

[0054] The output terminal of the amplifier U22 is connected to the second terminal of resistor R23 and the first terminal of resistor R25 respectively. The second terminal of resistor R25 is connected to the non-inverting input terminal of amplifier U23 and the first terminal of resistor R24 ​​respectively. The second terminal of resistor R24 ​​is connected to a power supply, which is a 3.3V power supply.

[0055] The output terminal of the amplifier U23 is connected to the first terminal of the resistor R26, and the second terminal of the resistor R26 is connected to the inverting input terminal of the amplifier U23; the output terminal of the amplifier U23 is used as the output terminal of the isolated current acquisition module and connected to the input terminal of the analog-to-digital conversion module.

[0056] In this embodiment, the current sensor U20 is model LF2010-S / SPA7. The current sensor U20 outputs a corresponding current signal in a linear proportion to the actual current magnitude. This current signal is shunted by resistors R21 and R22 and input to isolator U21. The isolator U21 in this embodiment is the same model as the isolator U11 in embodiment two, and the amplifiers U22 and U23 in this embodiment are also the same model as the amplifiers U12 and U13 in embodiment two. Therefore, the working principle of the subsequent circuit of isolator U21 is the same as that of the subsequent circuit of isolator U11 in embodiment two. Therefore, the isolated current acquisition module of this embodiment also has advantages such as strong anti-interference capability, strong load-carrying capacity, and high reliability.

[0057] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A UPS parallel circulating current suppression circuit, characterized in that, The circuit includes: multiple UPS units connected in parallel, a circulating current suppression control unit, and multiple acquisition units; each UPS module's output terminal is connected to an acquisition unit. Each acquisition unit includes: an isolated current acquisition module, an isolated voltage acquisition module, and an analog-to-digital converter module. The output terminals of the isolated current acquisition module and the isolated voltage acquisition module are both connected to the input terminal of the analog-to-digital converter module. The output terminal of the analog-to-digital converter module is connected to the input terminal of the circulating current suppression control unit. The control output terminal of the circulating current suppression control unit is connected to the controlled terminal of each UPS unit.

2. The UPS parallel circulating current suppression circuit according to claim 1, characterized in that, Each UPS unit includes a rectifier, a battery, and an inverter. The power output terminal of the rectifier is connected to the power input terminal of the inverter and the power terminal of the battery, respectively. The power terminal of the battery is also connected to the power input terminal of the inverter.

3. The UPS parallel circulating current suppression circuit according to claim 1, characterized in that, The isolated voltage acquisition module includes: sampling resistor R1, sampling resistor R2, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15, resistor R16, capacitor C11, isolator U11, bidirectional diode D11, amplifier U12, and amplifier U13. The first end of the sampling resistor R1 is connected to the first end of resistor R11 and the first end of capacitor C11 respectively. The second end of resistor R11 is connected to the first end of the input side of isolator U11. The first end of the sampling resistor R2 is connected to the first end of resistor R12 and the second end of capacitor C11 respectively. The second end of resistor R12 is connected to the second end of the input side of isolator U11. The first terminal of the output side of the isolator U11 is connected to the first terminal of the bidirectional diode D11 and the non-inverting input terminal of the amplifier U12, respectively. The second terminal of the output side of the isolator U11 is connected to the second terminal of the bidirectional diode D11, the inverting input terminal of the amplifier U12 and the first terminal of the resistor R13, respectively. The output terminal of the amplifier U12 is connected to the second terminal of resistor R13 and the first terminal of resistor R15 respectively. The second terminal of resistor R15 is connected to the non-inverting input terminal of amplifier U13 and the first terminal of resistor R14 respectively. The second terminal of resistor R14 is connected to the power supply. The output terminal of the amplifier U13 is connected to the first terminal of the resistor R16, and the second terminal of the resistor R16 is connected to the inverting input terminal of the amplifier U13; the output terminal of the amplifier U13 is used as the output terminal of the isolated voltage acquisition module and connected to the input terminal of the analog-to-digital conversion module.

4. The UPS parallel circulating current suppression circuit according to claim 3, characterized in that, Both the sampling resistor R1 and the sampling resistor R2 contain multiple resistors connected in series.

5. The UPS parallel circulating current suppression circuit according to claim 1, characterized in that, The isolated current acquisition module includes: a current sensor U20, resistors R21, R22, R23, R24, R25, and R26, an isolator U21, a bidirectional diode D21, an amplifier U22, and an amplifier U23. The output terminal of the current sensor U20 is connected to the first terminal of resistor R21 and the first terminal of resistor R22 respectively. The second terminal of resistor R22 is connected to the first terminal of the input side of isolator U21. The second terminal of resistor R21 is connected to the second terminal of the input side of isolator U21. The first terminal of the output side of the isolator U21 is connected to the first terminal of the bidirectional diode D21 and the non-inverting input terminal of the amplifier U22, respectively. The second terminal of the output side of the isolator U21 is connected to the second terminal of the bidirectional diode D21, the inverting input terminal of the amplifier U22, and the first terminal of the resistor R23, respectively. The output terminal of the amplifier U22 is connected to the second terminal of resistor R23 and the first terminal of resistor R25 respectively. The second terminal of resistor R25 is connected to the non-inverting input terminal of amplifier U23 and the first terminal of resistor R24 ​​respectively. The second terminal of resistor R24 ​​is connected to the power supply. The output terminal of the amplifier U23 is connected to the first terminal of the resistor R26, and the second terminal of the resistor R26 is connected to the inverting input terminal of the amplifier U23; the output terminal of the amplifier U23 is used as the output terminal of the isolated current acquisition module and connected to the input terminal of the analog-to-digital conversion module.

6. The UPS parallel circulating current suppression circuit according to claim 1, characterized in that, Also includes: An AC bus is used to connect the load, and the output of each UPS unit is connected to the AC bus.

7. The UPS parallel circulating current suppression circuit according to claim 1, characterized in that, The circulating current suppression control unit includes a controller and a PWM modulator. The PWM modulator is connected to the controller. The I / O port of the controller is used as the input terminal of the circulating current suppression control unit and connected to the output terminal of the analog-to-digital conversion module. The PWM output port of the PWM modulator is used as the control output terminal of the circulating current suppression control unit and connected to the controlled terminal of each UPS unit.

8. The UPS parallel circulating current suppression circuit according to claim 1, characterized in that, The number of UPS units is 2 to 4.

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