A configurable DC voltage power frequency uninterruptible power supply system

Abstract

This utility model relates to uninterruptible power supplies (UPS), and more particularly to a power frequency UPS system with configurable DC voltage. It includes: an input circuit breaker, whose input terminal is connected to mains power; an input isolation transformer, whose input terminal is connected to the output terminal of the input circuit breaker; a rectifier unit, whose input terminal is connected to the output terminal of the input isolation transformer; a battery pack connected to a DC bus; an inverter, whose input terminal is connected to the DC bus; an output isolation transformer, whose input terminal is connected to the output terminal of the inverter; and a static switching unit, one end of which is connected to the output terminal of the output isolation transformer, and the other end of which is connected to the AC output terminal of the system. The input isolation transformer and the output isolation transformer each have selectable first and second turns ratios. It is adaptable to battery packs composed of different numbers of lead-acid batteries connected in series, and is compatible with multiple DC voltage levels without replacing power devices.

Description

Technical Field

[0001] This utility model relates to uninterruptible power supplies, and more particularly to a power frequency uninterruptible power supply system with configurable DC voltage. Background Technology

[0002] Traditional industrial frequency AC uninterruptible power supplies (UPS) typically use fixed-ratio input and output isolation transformers. Their rectifier units and inverters are only compatible with specific DC bus voltages, generally corresponding to 30 to 34 lead-acid batteries (three-phase system) or 16 to 18 lead-acid batteries (single-phase system) in series. When the user site has non-standard battery cell numbers (such as 20, 24, 32, 36, 40, 42, or 48 cells), existing equipment is difficult to directly accommodate, often requiring customized models or the addition of voltage conversion devices, thus increasing system complexity.

[0003] Furthermore, in application scenarios that require backup power for both AC and DC loads (such as frequency converters and DC switching power supplies), using independent battery packs for each subsystem will occupy more space and increase maintenance costs. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a power frequency uninterruptible power supply system with configurable DC voltage.

[0005] To achieve the above objectives, this utility model adopts the following technical solution: a power frequency uninterruptible power supply system with configurable DC voltage, comprising: The input circuit breaker (QFSR1) has its input terminals used to connect to the mains power supply. The input isolation transformer (TSR1) has its input terminal connected to the output terminal of the input circuit breaker (QFSR1); The rectifier unit has its input terminal connected to the output terminal of the input isolation transformer (TSR1) for converting AC power to DC power, and its output terminal is connected to the DC bus. The battery pack (GB1) is connected to the DC bus via a reverse protection diode (DFF1). The cathode of the reverse protection diode (DFF1) is connected to the output terminal of the rectifier unit, and the anode of the reverse protection diode (DFF1) is connected to the positive terminal of the battery pack (GB1). The inverter (UNB1) has its input connected to the DC bus and is used to invert DC power into AC power. The input terminal of the output isolation transformer (TSC1) is connected to the output terminal of the inverter (UNB1); A static switching unit, one end of which is connected to the output terminal of the output isolation transformer (TSC1), and the other end of which is connected to the AC output terminal of the system, which is used to connect external loads.

[0006] The input isolation transformer (TSR1) and the output isolation transformer (TSC1) have selectable first and second turns ratios, respectively, to adapt to different DC bus voltage levels.

[0007] Specifically, the input isolation transformer (TSR1) is configured to have a selectable first ratio, and the output isolation transformer (TSC1) is configured to have a selectable second ratio; the combination of the first ratio and the second ratio is used to adapt the system to different DC bus voltage levels generated by the battery pack (GB1) consisting of different numbers of batteries connected in series.

[0008] Furthermore, the AC output terminal includes an output switch (QFSC1), the input terminal of which is connected to the static switch unit, and the output terminal of which is connected to the load.

[0009] Furthermore, the rectifier unit includes a rectifier bridge (UZL1) and an electrolytic capacitor (CZL1); the input terminal of the rectifier bridge (UZL1) is connected to the output terminal of the input isolation transformer (TSR1); the output terminal of the rectifier bridge (UZL1), one end of the electrolytic capacitor (CZL1), the cathode of the anti-reverse diode (DFF1), and the input terminal of the inverter (UNB1) are all connected to the DC bus.

[0010] Furthermore, the static switching unit includes a first static switch (STS1) and a second static switch (STS2); one end of the first static switch (STS1) is connected to the output terminal of the output isolation transformer (TSC1); the other end of the first static switch (STS1) and one end of the second static switch (STS2) are connected together to the input terminal of the output switch (QFSC1); the output terminal of the output switch (QFSC1) constitutes the AC output terminal of the system for connecting the load; the other end of the second static switch (STS2) is connected to the output terminal of the bypass circuit breaker (QFPL1), and the input terminal of the bypass circuit breaker (QFPL1) is used to connect the mains bypass power supply.

[0011] Furthermore, the power supply system also includes an input filter capacitor (CLV1) and an output filter capacitor (CLV2), wherein the input filter capacitor (CLV1) is connected to the AC line between the output terminal of the input circuit breaker (QFSR1) and the input terminal of the input isolation transformer (TSR1); and the output filter capacitor (CLV2) is connected to the AC line at the output terminal of the output isolation transformer (TSC1).

[0012] The first turns ratio of the input isolation transformer (TSR1) is configured such that when the mains voltage fluctuates to 85% of its rated value, the DC voltage obtained after conversion by the rectifier unit is not lower than the float charge voltage of the battery pack (GB1).

[0013] The second turns ratio of the output isolation transformer (TSC1) is configured to match the maximum AC voltage that the inverter (UNB1) can output when the DC bus voltage drops to the minimum operating voltage, in order to maintain the stability of the final output voltage.

[0014] Furthermore, the battery pack (GB1) also supplies power to DC loads via DC load circuit breakers, the DC loads including at least one of frequency converters and DC switching power supplies.

[0015] Furthermore, the battery pack (GB1) consists of 16, 18, 20, 24, 30, 32, 36, 40, 42 or 48 lead-acid batteries connected in series.

[0016] Compared with the prior art, this utility model has the following advantages.

[0017] This utility model relates to a configurable DC voltage power frequency uninterruptible power supply system. By incorporating input and output isolation transformers with selectable turns ratios, the rectifier unit and inverter can operate normally under different DC bus voltages, thus adapting to battery packs composed of varying numbers of lead-acid batteries connected in series (e.g., 16 to 48 cells). It is compatible with multiple DC voltage levels without requiring replacement of power devices. Furthermore, by connecting the rectifier bridge output, electrolytic capacitors, anti-reverse diode cathodes, and inverter input to the same DC bus, and employing a static switch in conjunction with a bypass circuit breaker to achieve main-bypass switching, the system's compact structure and power supply reliability are ensured. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the following description.

[0019] Figure 1 This is a schematic diagram illustrating an application scenario of a power frequency uninterruptible power supply system with configurable DC voltage.

[0020] Figure 2 This is a schematic diagram of a power frequency uninterruptible power supply system with configurable DC voltage, as shown in the embodiment.

[0021] Figure 3 This is the input-side L-phase conducted interference analysis diagram.

[0022] Figure 4 This is the input-side N-phase conducted interference analysis diagram.

[0023] Figure 5 This is the output side L-phase conducted interference analysis diagram.

[0024] Figure 6 This is the output-side N-phase conducted interference analysis diagram.

[0025] Figure 7 This is a graph showing the product's radiation interference (horizontal polarization) analysis.

[0026] Figure 8 This is a diagram showing the product's radiation interference (vertical polarization) analysis. Detailed Implementation

[0027] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0028] The terminology used in the embodiments of this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The singular forms “a,” “the,” and “the” as used in the embodiments of this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0029] Depending on the context, words such as “if” or “suppose” used here can be interpreted as “when”, “when”, “in response to determination”, or “in response to detection”.

[0030] For ease of understanding, the embodiments of this disclosure will be described in detail first.

[0031] Example 1, such as Figure 1 As shown, an example of an application scenario is as follows: The input terminal of the charging circuit breaker is connected to the mains power, and the other end of the charging circuit breaker is connected to the input terminal of the charging module. The other end of the charging module is connected to the battery pack, the DC inverter load circuit breaker QFHZ1, the DC switching power supply load circuit breaker QFLZ1, and the DC terminal of the power frequency AC uninterruptible power supply UAC1. The DC inverter load circuit breaker QFHZ1 is connected to the inverter. The DC switching power supply load circuit breaker QFLZ1 is connected to the switching power supply UDC1. The input terminal of the power frequency AC uninterruptible power supply switch QFAC1 is connected to the mains power, the output terminal of the power frequency AC uninterruptible power supply switch QFAC1 is connected to the input terminal of the power frequency AC uninterruptible power supply UAC1, and the output terminal of the power frequency AC uninterruptible power supply UAC1 is connected to the AC load.

[0032] This embodiment is a comprehensive AC / DC power supply system, commonly used as a backup power system for inverter-driven loads, also known as a low-voltage ride-through device. It also includes DC / DC power output to power instruments, possibly at DC 24V or other voltages. The inverter's power supply is the primary output, with a capacity ranging from tens to hundreds of kilowatts. In actual operation, the inverter's power supply is provided by a battery, and the control power supply (start signal) must be an uninterruptible power supply (UPS) to ensure the system is unaffected by mains power anomalies. Therefore, a power frequency UPS (Uninterruptible Power Supply) UAC1 is needed. Power frequency UPSs generally have a relatively small capacity, perhaps 6-10 kVA. However, a separate battery system cannot be configured solely for this small-capacity UPS. Therefore, configuring a battery system requires consideration of battery switches, battery power cables, battery monitoring equipment, etc., resulting in higher overall costs and more complex system design. The power frequency UPS UAC1 is designed to adapt to the inverter's DC bus voltage level; the entire power supply system has extremely high compatibility.

[0033] Example 2, as follows Figure 2 As shown, the configurable DC voltage power frequency uninterruptible power supply system includes: input circuit breaker QFSR1, input filter capacitor CLV1, input isolation transformer TSR1, rectifier bridge UZL1, electrolytic capacitor CZL1, anti-reverse diode DFF1, battery pack GB1, inverter UNB1, output isolation transformer TSC1, output filter capacitor CLV2, first static switch STS1, second static switch STS2, bypass circuit breaker QFPL1, and output switch QFSC1.

[0034] The input terminal of the input circuit breaker QFSR1 is connected to the mains power supply, connecting two live wires with a line voltage of AC 380V. The output terminal of the input circuit breaker QFSR1 is connected to one end of the input filter capacitor CLV1 and the input terminal of the input isolation transformer TSR1. The output terminal of the input isolation transformer TSR1 is connected to the input terminal of the rectifier bridge UZL1, with an output voltage of 460V. The output terminal of the rectifier bridge UZL1 is connected to one end of the electrolytic capacitor CZL1, the negative terminal of the reverse protection diode DFF1, and the input terminal of the inverter UNB1, with an output voltage of approximately 650V. The reverse protection diode DFF1 is connected to one end of the battery pack GB1. The battery pack voltage is for separate charging of other charging modules, with a float charge voltage of 540V. The inverter UNB1... 1. The output terminal is connected to the input terminal of the output isolation transformer TSC1; the output voltage of inverter UNB1 is a PWM waveform with an effective value of 230V; the output terminal of the output isolation transformer TSC1 is connected to one end of the output filter capacitor CLV2 and one end of the first static switch STS1; the output voltage of the output isolation transformer TSC1 is 220V; the other end of the first static switch STS1 is connected to the input terminal of the output switch QFSC1 and one end of the second static switch STS2; the other end of the second static switch STS2 is connected to the output terminal of the bypass circuit breaker QFPL1, and the input terminal of the bypass circuit breaker QFPL1 is connected to the mains power; the connection voltage is 220V, single phase; the first static switch STS1 and the second static switch STS2 together form the static bypass switching function.

[0035] As a preferred option, the turns ratio of the output isolation transformer is selected by configuring the relevant parameters of the power frequency uninterruptible power supply according to the DC bus voltage level of the original system, thereby achieving a rapid system configuration scheme. In this example, the DC bus consists of 40 12V batteries, each with a float charge voltage of 40 * 13.5 = 540V. Therefore, the effective output voltage at the lowest possible battery operating voltage must be considered. Generally, 10.5V per battery is considered the lowest possible operating voltage, but this can be adjusted for some special systems. Thus, the lowest possible operating DC bus voltage is: 40 * 10.5V = 420V; the corresponding output AC voltage is: 420 * 0.8 / ≈238V; where 0.8 is the modulation ratio of the PWM modulation wave, which is usually between 0.7 and 0.9 and will never be 1; because the output voltage drop and other factors need to be considered, it is rounded down in the final engineering application, that is, 230V; the output isolation transformer is selected as a single-phase isolation transformer with 230V input and 220V output, based on the input voltage and the voltage required at the end.

[0036] As a preferred option, the input isolation transformer turns ratio is selected as follows: the DC bus is formed by 40 12V batteries connected in series, and the float charge voltage needs to be considered as 40 * 13.5V = 540V; the corresponding rectifier bridge input voltage for 540V is: 540 / =382V; This voltage is lower than the mains voltage when it drops to 0.85 times the rated value. 0.85 is the DC input voltage range specified by the national standard. Therefore, the normal mains input voltage should reach 382 / 0.85≈449V. According to engineering experience, this voltage value needs to be rounded up. Therefore, the final value is 460V AC. So the input voltage of the isolation transformer is 380V dual live wire; the output voltage is 460V.

[0037] Conducted interference on the input side L phase: like Figure 3 As shown in Table 1, within the entire data acquisition range, the maximum value was 54.46 dBuV acquired in the 0.1635MHz band, far less than the national standard requirement of 79 dBuV; the maximum average value was 30.54 dBuV acquired in the 17.43MHz band, which is also far less than the national standard requirement of 60 dBuV. See Table 1 below for details: Conducted interference on the input side N-phase: such as Figure 4 According to Table 2, the maximum value collected across the entire data acquisition range was 51.68 dBuV at a frequency of 0.1635 MHz, which is far less than the national standard requirement of 79 dBuV. The maximum average value was 30.55 dBuV at a frequency of 0.24 MHz, which is also far less than the national standard requirement of 60 dBuV. See Table 2 below for details. Conducted interference on the input side L phase: such as Figure 5 According to Table 3, the maximum value collected across the entire data acquisition range was 40.73 dBuV in the 0.1815MHz band, which is far less than the national standard requirement of 64.42 dBuV. The maximum average value was 36.90 dBuV in the 0.1860MHz band, which is also far less than the national standard requirement of 54.21 dBuV. See Table 3 below for details. Conducted interference on the output side N-phase: such as Figure 6 According to Table 4, the maximum value collected across the entire data acquisition range was 40.30 dBuV in the 0.1860MHz band, which is far less than the national standard requirement of 64.21 dBuV. The maximum average value was 34.72 dBuV in the 0.1815MHz band, which is also far less than the national standard requirement of 54.42 dBuV. See Table 4 below for details. Product radiated interference (horizontally polarized antenna): such as Figure 7 As shown in Table 5, the maximum value collected across the entire data acquisition range was 23.41 dBuV / m at a frequency of 967.2625 MHz, which is far less than the national standard requirement of 57.00 dBuV / m. See Table 5 below for details. Product radiated interference (vertically polarized antenna): such as Figure 8 As shown in Table 6, the maximum value collected across the entire data acquisition range was 22.45 dBuV / m at a frequency of 131.8500 MHz, which is far less than the national standard requirement of 50.00 dBuV / m. See Table 6 below for details. Principle explanation of the configurable DC voltage power frequency uninterruptible power supply system: Modular transformer: It adopts a mature and reliable fixed-ratio input isolation transformer and output isolation transformer.

[0038] During the product design phase, based on the customer's required DC bus voltage (i.e., the number of batteries, such as 20, 28, 32, 36, 40, etc.), precise calculations are performed to match and install an input isolation transformer with the appropriate turns ratio. The transformer's turns ratio ensures that the rectifier can convert the grid AC voltage to the specific DC bus voltage required by the customer, allowing battery packs to be connected even when the mains power is below the lower limit of abnormal values.

[0039] Output synchronization matching: Synchronously, an output isolation transformer with the appropriate turns ratio is matched and installed. The turns ratio of this transformer ensures that the inverter can always output a stable, standard, high-quality AC voltage (such as 220V / 380V) under varying DC bus voltage.

[0040] Inverter Configuration: The control system firmware has multiple preset DC voltage operating modes. During factory shipment or field initialization, the current operating voltage level of the system can be set via the software menu. Based on this setting, the control system adjusts the control parameters of the rectifier and inverter (such as modulation ratio, voltage regulation point, etc.) to ensure the entire system operates at its optimal state, matching the transformer turns ratio.

[0041] Electromagnetic Compatibility (EMC): This equipment demonstrates excellent EMC performance. In conducted tests, the quasi-peak and average interference values ​​across the entire frequency band are significantly lower than the CISPR 13 CLASS A standard limits, with a margin of over 30dB. Interference propagating through power lines is effectively controlled and will not affect the power grid or surrounding equipment. On the radiated side, dual-dimensional tests covering the 30MHz-1GHz core frequency band with horizontal and vertical polarization show measured radiated field strengths of only 13.79-23.41dBμV / m, substantially lower than the standard limits, demonstrating outstanding spatial electromagnetic radiation suppression. The overall EMC design is mature and reliable, with both conducted and radiated interference control at an excellent level, meeting the stringent EMC requirements of industrial-grade equipment.

[0042] This invention realizes the standardized and modular adaptation of the DC side voltage of the power frequency AC uninterruptible power supply, breaking the limitation of a single voltage.

[0043] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "preferred embodiment," "detailed description," or "preferred embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Therefore, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of this utility model.

Claims

1. A power frequency uninterruptible power supply system with configurable DC voltage, characterized in that, include: An input circuit breaker, the input of which is used to connect to the mains power supply; An input isolation transformer has its input terminal connected to the output terminal of the input circuit breaker; a rectifier unit has its input terminal connected to the output terminal of the input isolation transformer, used to convert AC power to DC power, and its output terminal is connected to the DC bus; a battery pack is connected to the DC bus via a reverse protection diode, the cathode of which is connected to the output terminal of the rectifier unit, and the anode of which is connected to the positive terminal of the battery pack; and an inverter has its input terminal connected to the DC bus, used to invert DC power to AC power. An output isolation transformer has its input terminal connected to the output terminal of the inverter; a static switching unit has one end connected to the output terminal of the output isolation transformer and the other end connected to the AC output terminal of the system, which is used to connect external loads; the input isolation transformer and the output isolation transformer each have a selectable first transformation ratio and a second transformation ratio to adapt to different DC bus voltage levels.

2. The configurable DC voltage power frequency uninterruptible power supply system according to claim 1, characterized in that, The AC output terminal includes an output switch, the input terminal of which is connected to the static switch unit, and the output terminal of which is connected to the load.

3. The power frequency uninterruptible power supply system with configurable DC voltage according to claim 1, characterized in that, The rectifier unit includes a rectifier bridge and an electrolytic capacitor; the input terminal of the rectifier bridge is connected to the output terminal of the input isolation transformer; the output terminal of the rectifier bridge, one end of the electrolytic capacitor, the cathode of the anti-reverse diode, and the input terminal of the inverter are all connected to the DC bus.

4. The power frequency uninterruptible power supply system with configurable DC voltage according to claim 1, characterized in that, The static switch unit includes a first static switch and a second static switch; one end of the first static switch is connected to the output terminal of the output isolation transformer; the other end of the first static switch and one end of the second static switch are connected together to the input terminal of the output switch; the output terminal of the output switch constitutes the AC output terminal of the system, used to connect the load; the other end of the second static switch is connected to the output terminal of the bypass circuit breaker, and the input terminal of the bypass circuit breaker is used to connect the mains bypass power supply.

5. A power frequency uninterruptible power supply system with configurable DC voltage according to claim 1, characterized in that, The power supply system also includes an input filter capacitor and an output filter capacitor, wherein the input filter capacitor is connected to the AC line between the output terminal of the input circuit breaker and the input terminal of the input isolation transformer; and the output filter capacitor is connected to the AC line at the output terminal of the output isolation transformer.

6. A power frequency uninterruptible power supply system with configurable DC voltage according to claim 1, characterized in that, The battery pack also supplies power to DC loads via DC load circuit breakers, the DC loads including at least one of frequency converters and DC switching power supplies.

7. A power frequency uninterruptible power supply system with configurable DC voltage according to any one of claims 1-6, characterized in that, The battery pack consists of 16, 18, 20, 24, 30, 32, 36, 40, 42 or 48 lead-acid batteries connected in series.

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