Uninterruptible power supply system

Abstract

We provide uninterruptible power supply systems. [Solution] An uninterruptible power supply system comprising a bidirectional AC / DC converter, a resonant converter, an automatic voltage adjustment circuit, and a control unit, wherein when the AC input voltage is outside a predetermined voltage range but within the voltage adjustment range, the automatic voltage adjustment circuit, the resonant converter, and the bidirectional AC / DC converter generate an AC compensation voltage at the power output terminal based on the AC input voltage, and generate an AC output voltage based on the AC input voltage and the AC compensation voltage, so that the AC output voltage is within a predetermined voltage range, and when the AC input voltage is outside the voltage adjustment range, the resonant converter and the bidirectional AC / DC converter generate an AC output voltage at the power output terminal based on the battery discharge voltage, so that the AC output voltage is within a predetermined voltage range.

Description

Technical Field

[0001] The present disclosure relates to an uninterruptible power supply system, and particularly to a high-efficiency uninterruptible power supply system.

Background Art

[0002] Currently, commercially available interactive uninterruptible power supply systems (UPS) mainly employ an automatic voltage regulation (AVR) circuit with a low frequency of approximately 50 to 60 Hz, which is used for voltage regulation of the commercial power supply voltage and charging and discharging of the battery.

[0003] However, the disadvantages of the low-frequency automatic voltage regulation circuit are high cost of the number of elements, large volume, and heavy weight. In addition, the low-frequency automatic voltage regulation circuit has large iron loss during light load and high copper loss during heavy load, resulting in poor efficiency. For example, it is necessary to improve the existing uninterruptible power supply system to solve the above technical problems.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An uninterruptible power supply system for coupling an AC input voltage and a battery comprises: a bidirectional AC-DC converter coupled to a power input terminal to receive an AC input voltage and coupled to a power output terminal to output an AC output voltage; a resonant converter including a magnetic core and a transformer including a first coil, a second coil, and a third coil wound around the magnetic core, coupled to the bidirectional AC-DC converter and also coupled to a battery; an automatic voltage regulation circuit coupled to the third coil of the bidirectional AC-DC converter and the transformer, and also coupled to the power input terminal and the power output terminal; and a control unit coupled to the bidirectional AC-DC converter, the resonant converter, and the automatic voltage regulation circuit, wherein the AC input voltage falls outside a predetermined voltage range and When the voltage is within the voltage adjustment range, the control unit causes the automatic voltage adjustment circuit, resonant converter, and bidirectional AC / DC converter to generate an AC compensation voltage at the power output terminal based on the AC input voltage, and also generates an AC output voltage based on the AC input voltage and the AC compensation voltage, and is set so that the AC output voltage is within a predetermined voltage range. When the AC input voltage falls outside the voltage adjustment range, the control unit causes the resonant converter and bidirectional AC / DC converter to generate an AC output voltage at the power output terminal based on the battery discharge voltage, and is set so that the AC output voltage is within a predetermined voltage range. The voltage adjustment range is an uninterruptible power supply system in which the maximum value is greater than the maximum value of the predetermined voltage range and the minimum value is less than the minimum value of the predetermined voltage range. [Effects of the Invention]

[0005] The uninterruptible power supply system of this disclosure, with the above configuration and operating mode, can improve efficiency and reduce the cost of the number of components. [Brief explanation of the drawing]

[0006] You can gain a better understanding of the contents of this disclosure by referring to and reviewing the detailed descriptions of the embodiments below. [Figure 1] This is a block diagram of one embodiment of the uninterruptible power supply system disclosed herein. [Figure 2A]Figure 1 is a partial circuit block diagram of one embodiment of an uninterruptible power supply system. [Figure 2B] Figure 2A is a circuit diagram of one embodiment. [Figure 3A] Figures 1 and 2 are schematic diagrams of one embodiment in which the uninterruptible power supply system operates in bypass output mode. [Figure 3B] Figures 1 and 2 are schematic diagrams of one embodiment in which an uninterruptible power supply system operates in a step-down output voltage regulation mode. [Figure 3C] Figures 1 and 2 are schematic diagrams of one embodiment in which an uninterruptible power supply system operates in a boosted output voltage regulation mode. [Figure 3D] Figures 1 and 2 are schematic diagrams of one embodiment in which the uninterruptible power supply system operates in battery-powered mode. [Figure 4] This is one embodiment of the various operating modes of the conversion circuit for an uninterruptible power supply system. [Modes for carrying out the invention]

[0007] The following describes examples in detail with reference to the attached drawings. However, the specific examples described are for illustrative purposes only and do not limit the present invention. The descriptions of structural operations do not restrict the order of their execution. Any device having the same effect as a result of a rearranged structure of elements is included within the scope of this disclosure.

[0008] Unless otherwise specified, the terms used throughout this specification and claims have their usual meanings in the art, in the context of this disclosure, and in specific contexts.

[0009] As used in this text, “coupling” or “connection” may refer to two or more elements making direct physical or electrical contact with each other, or indirect physical or electrical contact with each other, or it may refer to two or more elements operating or interacting with each other.

[0010] Please refer to Figure 1, a block diagram of one embodiment of the uninterruptible power supply system 100 according to this disclosure. As shown in Figure 1, the uninterruptible power supply system 100 is used to couple an AC input voltage I / P with a battery 102 and comprises a first relay RY1, a second relay RY2, a bidirectional AC-DC converter 104, a resonant converter 106, and an automatic voltage regulation circuit 108.

[0011] In one embodiment, the AC input voltage I / P is a commercial voltage, and the battery 102 can be a power storage device with charge / discharge capabilities, such as a lead-acid battery, nickel-cadmium battery (Ni-Cd), nickel-metal hydride battery (Ni-MH), or lithium-ion battery (Li-ion). When the AC input voltage I / P is within a predetermined voltage range, the uninterruptible power supply system 100 charges the battery 102 using the AC input voltage I / P as a power source, and simultaneously generates an AC output voltage O / P based on the AC input voltage I / P and supplies it to the load. For example, the AC input voltage I / P is bypassed and supplied directly to the load as the AC output voltage O / P. When the AC input voltage I / P falls outside the predetermined voltage range (for example, the voltage is higher than the predetermined voltage range, or lower but within the voltage adjustment range), the uninterruptible power supply system 100 generates an appropriate AC output voltage O / P based on the AC input voltage I / P using an automatic voltage adjustment circuit 108 and supplies it to the load, so that the AC output voltage O / P is within the predetermined voltage range. If the AC input voltage I / P is abnormal (for example, if it falls outside the adjustable voltage range of the uninterruptible power supply system 100, such as due to a power outage, voltage being too low or too high), the uninterruptible power supply system 100 uses the power stored in the battery 102 to generate an AC output voltage O / P and supply it to the load, so that the AC output voltage O / P is within a predetermined voltage range.

[0012] The bidirectional AC-DC converter 104 can perform AC-DC conversion or DC-AC conversion based on the installation (i.e., control) of the control unit 110. The resonant converter 106 can employ a bidirectional LLC full bridge converter or a bidirectional DC-DC converter of other suitable configuration. The automatic voltage regulation circuit 108 can employ a high-frequency switching type automatic voltage regulation (AVR). For example, for a commercial power supply frequency of 50-60Hz, the control unit 110 sets the switching circuit of the automatic voltage regulation circuit 108 to switch at a frequency 10 times or more (e.g., 1KHz or more) to perform voltage regulation.

[0013] The uninterruptible power supply system 100 charges the battery 102 based on the commercial power supply voltage, generates an AC output voltage O / P based on the commercial power supply voltage and supplies power, or generates an AC output voltage O / P based on the discharge of the battery 102 and supplies power.

[0014] The control unit 110 of the uninterruptible power supply system 100 uses high-frequency control signals to control the conduction state of the switching circuits of the bidirectional AC-DC converter 104, the resonant converter 106, and / or the automatic voltage regulation circuit 108, thereby regulating the AC output voltage O / P and charging and discharging the battery 102. The switching circuits can be composed of semiconductor elements (e.g., switches composed of transistors, diodes, and / or other circuit elements), and the AC output voltage O / P is adjusted and compensated via the resonant converter 106, the bidirectional AC-DC converter 104, and the automatic voltage regulation circuit 108. Compared to a low-frequency automatic voltage regulator, the uninterruptible power supply system 100 has fewer relays and lower iron loss at light loads and copper loss at heavy loads of the high-frequency operating transformer TR, thus reducing the cost of the number of elements, the weight and volume of the equipment, and losses in copper and iron loss, and improving efficiency.

[0015] For the technical content regarding the circuit structures and functional operations of the first relay RY1, the second relay RY2, the bidirectional AC / DC converter 104, the resonant converter 106, and the automatic voltage regulation circuit 108 of the uninterruptible power supply system 100, please refer to the following description.

[0016] The power input terminal Pin of the uninterruptible power supply system 100 has a live wire terminal L and a neutral terminal N, and the power output terminal Pout has a live wire terminal L' and a neutral terminal N'. The first relay RY1 is coupled to the power input terminal Pin and the bidirectional AC / DC converter 104 and is used to receive or cut off the AC input voltage I / P. In one embodiment, the first relay RY1 includes a first input relay RY1a and a first neutral relay RY1b. The first input relay RY1a is coupled to the live wire terminal L of the power input terminal Pin, and the first neutral relay RY1b is coupled to the neutral terminal N of the power input terminal Pin and the neutral terminal N' of the power output terminal Pout.

[0017] The second relay RY2 is coupled to the power output terminal Pout and the bidirectional AC / DC converter 104 and is used to output the AC output voltage O / P.

[0018] The bidirectional AC / DC converter 104 is coupled to the power input terminal Pin via the first relay RY1 and is used to receive the AC input voltage I / P, and is also used to be coupled to the power output terminal Pout via the second relay RY2.

[0019] The resonant converter 106 is coupled to the bidirectional AC / DC converter 104 and is used to be coupled to the battery 102.

[0020] The automatic voltage regulation circuit 108 is coupled to the bidirectional AC / DC converter 104 and is used to be coupled to the live wire terminal L of the power input terminal Pin and the live wire terminal L' of the power output terminal Pout. The automatic voltage regulation circuit 108 is coupled to the live wire terminal L of the power input terminal Pin via the first relay RY1 and is coupled to the live wire terminal L' of the power output terminal Pout via the second relay RY2.

[0021] The uninterruptible power supply system 100 further includes a control unit 110. The control unit 110 is coupled to at least one of a first relay RY1, a second relay RY2, a battery 102, a bidirectional AC / DC converter 104, a resonant converter 106, and an automatic voltage regulation circuit 108, and controls the operations of the first relay RY1, the second relay RY2, the battery 102, the bidirectional AC / DC converter 104, the resonant converter 106, and the automatic voltage regulation circuit 108, respectively. By way of example, the control unit 110 can transmit control signals to the first relay RY1 and the second relay RY2 to control the conduction states (e.g., conduction or non-conduction) of the first relay RY1 and the second relay RY2, and can transmit control signals to the bidirectional AC / DC converter 104, the resonant converter 106, and the automatic voltage regulation circuit 108 to control the conduction states (e.g., conduction or non-conduction) of the switches within these elements. In one embodiment, the control unit 110 can control the bidirectional AC / DC converter 104 to perform functions such as an Active Power Filter (APF) or Power Factor Correction (PFC). In one embodiment, the control unit 110 may include circuit elements such as one or more micro control units (MCUs) or a Central Processing Unit (CPU).

[0022] Please refer to FIG. 2A, which is a partial circuit block diagram of the uninterruptible power supply system 100 in FIG. 1. For ease of explanation, only the first relay RY1, the second relay RY2, the battery 102, the bidirectional AC / DC converter 104, the resonant converter 106, and the automatic voltage regulation circuit 108 are shown in FIG. 2A.

[0023] In the embodiment of FIG. 2A, the bidirectional AC / DC converter 104 includes a first resonant circuit 104a and a first conversion circuit 104b. The first conversion circuit 104b is coupled to the first resonant circuit 104a, and the first resonant circuit 104a is coupled to the automatic voltage regulation circuit 108 and the power output terminal Pout.

[0024] In the embodiment shown in Figure 2A, the resonant converter 106 includes a second conversion circuit 106a, a third conversion circuit 106b, a second resonant circuit 106c, a charging switch circuit 106d, a fourth capacitor C4, and a transformer TR. The second conversion circuit 106a is coupled to the first conversion circuit 104b. The fourth capacitor C4 is coupled between the first conversion circuit 104b and the second conversion circuit 106a. The second resonant circuit 106c is coupled to the second conversion circuit 106a, the transformer TR is coupled to the second resonant circuit 106c and the charging switch circuit 106d, and the charging switch circuit 106d is coupled to the transformer TR and the third conversion circuit 106b. The third conversion circuit 106b is coupled to the charging switch circuit 106d and the transformer TR. The battery 102 is coupled to the third conversion circuit 106b. Furthermore, the charging switch circuit 106d may be provided in another suitable location. In another embodiment, the charging switch circuit 106d is provided between the battery 102 and the third conversion circuit 106b, and the control unit 110 sets the charging switch circuit 106d to a conductive state, thereby charging or discharging the battery 102. In yet another embodiment, the charging switch circuit is provided inside the battery 102, and the control unit 110 does not set the charging switch circuit to a conductive state. In yet another embodiment, the charging switch circuit 106d may be omitted.

[0025] In the embodiment shown in Figure 2A, the automatic voltage regulation circuit 108 includes a fourth conversion circuit 108a, a fifth conversion circuit 108b, a third resonant circuit 108c, and a second capacitor C2. The third resonant circuit 108c is coupled to the power input terminal Pin and the first resonant circuit 104a. The fourth conversion circuit 108a is coupled to the third resonant circuit 108c. The second capacitor C2 is coupled to the fourth conversion circuit 108a. The fifth conversion circuit 108b is coupled to the fourth conversion circuit 108a, the second capacitor C2, and the transformer TR.

[0026] In the embodiment shown in Figure 2B, the first resonant circuit 104a includes a third capacitor C3 and a second inductor L2. The first conversion circuit 104b includes a ninth switch Q9, a tenth switch Q10, an eleventh switch Q11, and a twelfth switch Q12. The first terminal of the third capacitor C3 is coupled to the second relay RY2, the second terminal of the first capacitor C1 (third resonant circuit 108c), and the first terminal of the second inductor L2. The first terminal of the ninth switch Q9 is coupled to the second terminal of the second inductor L2 and the first terminal of the tenth switch Q10. The first terminal of the eleventh switch Q11 is coupled to the second terminal of the third capacitor C3 and the first terminal of the twelfth switch Q12, the second terminal of the eleventh switch Q11 is coupled to the second terminal of the ninth switch Q9, and the second terminal of the twelfth switch Q12 is coupled to the second terminal of the tenth switch Q10.

[0027] In one embodiment, the control unit 110 controls the switch control signals (not shown) of the 9th switch Q9, 10th switch Q10, 11th switch Q11, and 12th switch Q12 of the first conversion circuit 104b as high-frequency switching pulse width modulation (PWM) signals, with the frequency of the switch control signals being 10 kHz or higher. In one embodiment, the switches of the first conversion circuit 104b are implemented in the form of transistors, and the control unit 110 supplies the switch control signals to the gate terminals of the 9th switch Q9, 10th switch Q10, 11th switch Q11, and 12th switch Q12 to control the conduction state of these switches. In another embodiment, the control unit 110 may also employ forms such as pulse frequency modulation signals (PFM) or pulse omission modulation signals (PSM) as switch control signals. The control unit 110 controls the first conversion circuit 104b to perform AC-DC conversion or DC-AC conversion.

[0028] In the embodiment shown in Figure 2B, the second conversion circuit 106a includes the 13th switch Q13, the 14th switch Q14, the 15th switch Q15, and the 16th switch Q16. The third conversion circuit 106b includes the 19th switch Q19, the 20th switch Q20, the 21st switch Q21, and the 22nd switch Q22. The second resonant circuit 106c includes the 5th capacitor C5 and the 3rd inductor L3. The charging switch circuit 106d includes the 17th switch Q17 and the 18th switch Q18. The transformer TR includes a magnetic core M, a first coil N1 wound around the magnetic core M, a second coil N2 wound around the magnetic core M, and a third coil N3 wound around the magnetic core M, the third coil N3 being coupled to the automatic voltage adjustment circuit 108, and providing the necessary voltage conversion for the resonant converter 106 and the automatic voltage adjustment circuit 108. In another embodiment, the transformer TR may include one or more magnetic cores and corresponding coils to provide the voltage conversion required for the resonant converter 106 and the automatic voltage regulation circuit 108. In another embodiment, the uninterruptible power supply system 100 may include one or more transformers to provide the voltage conversion required for the resonant converter 106 and the automatic voltage regulation circuit 108.

[0029] The fourth capacitor C4 has its first end connected to the second end of the eleventh switch Q11, the first end of the thirteenth switch Q13, and the first end of the fifteenth switch Q15, and its second end connected to the second end of the twelfth switch Q12, the second end of the fourteenth switch Q14, and the second end of the sixteenth switch Q16. The first end of the fourteenth switch Q14 is connected to the second end of the thirteenth switch Q13, and the first end of the sixteenth switch Q16 is connected to the second end of the fifteenth switch Q15. The third inductor L3 has its first end connected to the second end of the fifteenth switch Q15 and the first end of the sixteenth switch Q16, and its second end is connected to the first end of the first coil N1. The fifth capacitor C5 has its first end connected to the second end of the thirteenth switch Q13 and the first end of the fourteenth switch Q14, and its second end is connected to the second end of the first coil N1. The first end of the 17th switch Q17 is connected to the first end of the 2nd coil N2. The 18th switch Q18 has its first end connected to the second end of the 17th switch Q17, and its second end is connected to the first end of the 19th switch Q19 and the first end of the 20th switch Q20. The second end of the 2nd coil N2 is connected to the first end of the 21st switch Q21 and the first end of the 22nd switch Q22. The second end of the 21st switch Q21 is connected to the second end of the 19th switch Q19 and the first end of the battery 102. The second end of the 22nd switch Q22 is connected to the second end of the 20th switch Q20 and the second end of the battery 102.

[0030] The control unit 110 is used to implement switch control signals (not shown) for the 13th switch Q13, 14th switch Q14, 15th switch Q15, and 16th switch Q16 of the second conversion circuit 106a, and the 19th switch Q19, 20th switch Q20, 21st switch Q21, and 22nd switch Q22 of the third conversion circuit 106b as appropriate signals such as PWM, PFM, and PSM for high-frequency switching at a frequency of 10 kHz or higher. In one embodiment, the switches of the second conversion circuit 106a and the third conversion circuit 106b are implemented in the form of transistors, and the control unit 110 supplies switch control signals to the gate terminals of the 13th switch Q13, the 14th switch Q14, the 15th switch Q15, the 16th switch Q16, the 19th switch Q19, the 20th switch Q20, the 21st switch Q21, and the 22nd switch Q22, thereby controlling the conduction state of these switches and performing AC-DC conversion or DC-AC conversion by setting up the second conversion circuit 106a and the third conversion circuit 106b, respectively.

[0031] In the embodiment shown in Figure 2B, the fourth conversion circuit 108a includes a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4. The fifth conversion circuit 108b includes a fifth switch Q5, a sixth switch Q6, a seventh switch Q7, and an eighth switch Q8. The third resonant circuit 108c includes a first capacitor C1 and a first inductor L1. The first end of the first capacitor C1 is coupled to the first relay RY1, and the second end is coupled to the second relay RY2 and the bidirectional AC-DC converter 104. The first end of the first inductor L1 is coupled to the first relay RY1 and the first end of the first capacitor C1. The first end of the first switch Q1 is coupled to the second end of the first inductor L1 and the first end of the second switch Q2. The first end of the third switch Q3 is coupled to the second end of the first capacitor C1 and the first end of the fourth switch Q4, and the second end is coupled to the second end of the first switch Q1. The second terminal of the fourth switch Q4 is connected to the second terminal of the second switch Q2. The first terminal of the second capacitor C2 is connected to the second terminal of the first switch Q1 and the second terminal of the third switch Q3, and the second terminal of the second switch Q2 and the second terminal of the fourth switch Q4 is connected to the second terminal of the second switch Q2 and the second terminal of the fourth switch Q4. The first terminal of the fifth switch Q5 is connected to the first terminal of the third coil N3 and the first terminal of the sixth switch Q6, and the second terminal of the fifth switch Q5 is connected to the first terminal of the second capacitor C2, and the second terminal of the sixth switch Q6 is connected to the second terminal of the second capacitor C2. The first terminal of the seventh switch Q7 is connected to the second terminal of the third coil N3 and the first terminal of the eighth switch Q8, and the second terminal of the seventh switch Q7 is connected to the second terminal of the fifth switch Q5. The second terminal of the eighth switch Q8 is connected to the second terminal of the sixth switch Q6.

[0032] The control unit 110 is used to control the switch control signals (not shown) of the first switch Q1, second switch Q2, third switch Q3, and fourth switch Q4 of the fourth conversion circuit 108a, and the fifth switch Q5, sixth switch Q6, seventh switch Q7, and eighth switch Q8 of the fifth conversion circuit 108b. This can be done with appropriate signals such as high-frequency switching PWM, PFM, or PSM, and the frequency of the switch control signals is 10 kHz or higher. In one embodiment, the control unit 110 supplies adjustment signals to the gate terminals of the first switch Q1, second switch Q2, third switch Q3, fourth switch Q4, fifth switch Q5, sixth switch Q6, seventh switch Q7, and eighth switch Q8, and controls the conduction state of these switches, thereby setting up the fourth conversion circuit 108a and the fifth conversion circuit 108b, respectively, to perform AC-DC conversion or DC-AC conversion operation. Furthermore, the control unit 110 may also control the second switch Q2 and the fourth switch Q4 of the fourth conversion circuit 108a to conduct and the first switch Q1 and the third switch Q3 to deconduct, thereby bypassing the AC input voltage I / P to the bidirectional AC-DC converter 104 and the power output terminal Pout.

[0033] Figures 3A to 3D are schematic diagrams of the uninterruptible power supply system 100 shown in Figures 1 and 2A to 2B operating in different modes. Figure 3A is a schematic diagram of one embodiment in which the uninterruptible power supply system 100 operates in bypass output mode. Figure 3B is a schematic diagram of one embodiment in which the uninterruptible power supply system 100 operates in step-down output voltage regulation mode. Figure 3C is a schematic diagram of one embodiment in which the uninterruptible power supply system 100 operates in step-up output voltage regulation mode. Figure 3D is a schematic diagram of one embodiment in which the uninterruptible power supply system 100 operates in battery supply mode.

[0034] When the uninterruptible power supply system 100 is in the operating mode shown in Figure 3A, the control unit 110 is configured to receive the AC input voltage I / P by conducting the first relay RY1. The control unit 110 is configured to transmit the AC input voltage I / P to the bidirectional AC-DC converter 104 via the third resonant circuit 108c and the fourth conversion circuit 108a by controlling the second switch Q2 and the fourth switch Q4 of the fourth conversion circuit 108a to conduct and switches Q1 and Q3 to deconduct. The bidirectional AC-DC converter 104 converts the received AC input voltage I / P between AC and DC to generate a first DC voltage DC1, which is stored across the fourth capacitor C4. The resonant converter 106 converts the first DC voltage DC1 into a charging voltage CV1 (for example, the control unit 110 installs a second conversion circuit 106a, a second resonant circuit 106c, a transformer TR, a charging switch circuit 106d, and a third conversion circuit 106b to convert the first DC voltage DC1 into a charging voltage CV1), and uses the charging voltage CV1 to charge the battery 102, which may be a fixed or variable appropriate voltage value. In one embodiment, the control unit 110 may charge the battery 102 in the form of constant current charging or constant voltage charging. However, the control unit 110 installs a second conversion circuit 106a to perform DC-AC conversion based on the first DC voltage DC1 and generates a first AC conversion signal AC1, the transformer TR generates a third AC conversion signal AC3 based on the first AC conversion signal AC1, and the control unit 110 installs an automatic voltage adjustment circuit 108 to perform AC-DC conversion based on the third AC conversion signal AC3 and generates a compensation voltage AV1 across the second capacitor C2.

[0035] In the embodiment shown in Figure 3A, the control unit 110 conducts the first relay RY1 and a portion of the fourth conversion circuit 108a (i.e., the second switch Q2 and the fourth switch Q4 conduct, and the first switch Q1 and the third switch Q3 do not conduct). The AC input voltage I / P is transmitted to the first conversion circuit 104b via the first relay RY1, the third resonant circuit 108c, the fourth conversion circuit 108a, and the first resonant circuit 104a. The control unit 110 then installs the first conversion circuit 104b to perform AC-DC conversion and generates a first DC voltage DC1 at the fourth capacitor C4 of the resonant converter 106 based on the AC input voltage I / P.

[0036] In the embodiment shown in Figure 3A, the control unit 110 sets the first relay RY1 to conduct, sets a portion of the fourth conversion circuit 108a to conduct (i.e., the second switch Q2 and the fourth switch Q4 conduct, and the first switch Q1 and the third switch Q3 do not conduct), and sets the charging switch circuit 106d to conduct (i.e., the 17th switch Q17 and the 18th switch Q18 conduct). The second conversion circuit 106a converts the first DC voltage DC1 into a first AC conversion signal AC1 or another suitable AC signal. In one embodiment, the first AC conversion signal AC1 is a high-frequency signal, for example, the frequency of the first AC conversion signal AC1 is set to 10 kHz or higher. Based on the first AC conversion signal AC1, the transformer TR generates the second and third AC conversion signals AC2 and AC3 in the charging switch circuit 106d and the fifth conversion circuit 108b, respectively. The charging switch circuit 106d receives the second AC conversion signal AC2 and transmits it to the third conversion circuit 106b. When the charging switch circuit 106d is conducting, the third conversion circuit 106b receives the second AC conversion signal AC2, converts it to a charging voltage CV1, and charges the battery 102 with the charging voltage CV1. The fifth conversion circuit 108b converts the third AC conversion signal AC3 to a compensation voltage AV1 and establishes the compensation voltage AV1 on the second capacitor C2.

[0037] In one embodiment, the control unit 110 controls the bidirectional AC-DC converter 104 and the resonant converter 106 to adjust the charging voltage CV1 of the battery 102 and perform charging operations such as constant voltage charging or constant current charging. In one embodiment, when the energy of the battery 102 is oversaturated or saturated (i.e., when the voltage of the battery 102 is above a voltage threshold), the control unit 110 prevents the 17th switch Q17 and the 18th switch Q18 from conducting, thereby preventing damage to the battery 102 due to excessive energy accumulation (i.e., excessive charging voltage CV1).

[0038] In the uninterruptible power supply system 100, the control unit 110 detects the voltage value of the AC input voltage I / P (for example, determined based on the voltage signal of the AC input voltage I / P detected by a sensor installed at an appropriate location such as the power input terminal Pin in the control unit 110) and determines which mode the uninterruptible power supply system 100 will operate in. If the control unit 110 determines that the voltage value of the AC input voltage I / P is within a predetermined voltage range (for example, 90V to 130V), it is configured to operate the uninterruptible power supply system 100 in bypass output mode and is configured with an automatic voltage adjustment circuit 108 to bypass output the AC input voltage I / P as an AC output voltage O / P via the first relay RY1, the fourth conversion circuit 108a (with the second switch Q2 and the fourth switch Q4 conducting, and the first switch Q1 and the third switch Q3 not conducting), and the second relay RY2.

[0039] When the uninterruptible power supply system 100 is in the operating mode shown in Figures 3B to 3C, the control unit 110 is configured to operate the uninterruptible power supply system 100 in voltage adjustment mode if it determines that the voltage value of the AC input voltage I / P is outside a predetermined voltage range but within the voltage adjustment range (for example, 60V to 90V or 130V to 150V). Depending on whether the voltage value of the AC input voltage I / P is higher or lower than the predetermined voltage range, the control unit 110 controls the automatic voltage adjustment circuit 108 to generate an AC compensation voltage Vcomp based on the AC input voltage I / P, and to generate an AC output voltage O / P based on the AC input voltage I / P and the AC compensation voltage Vcomp (for example, by superimposing the AC input voltage I / P and the AC compensation voltage Vcomp to obtain the AC output voltage O / P), so that the AC output voltage O / P is within the predetermined voltage range. In one embodiment, the maximum value of the voltage adjustment range is greater than the maximum value of the predetermined voltage range, and the minimum value of the voltage adjustment range is smaller than the minimum value of the predetermined voltage range. In another embodiment, only the maximum value of the voltage adjustment range may be set to be greater than the maximum value of a predetermined voltage range (the minimum value is the same), or only the minimum value of the voltage adjustment range may be set to be less than the minimum value of a predetermined voltage range (the maximum value is the same).

[0040] In the embodiment shown in Figure 3B, if the voltage value of the AC input voltage I / P exceeds the upper limit of a predetermined voltage range but is within the voltage adjustment range, the control unit 110 determines that the AC input voltage I / P exceeds the predetermined voltage range and executes the voltage adjustment function to lower the AC input voltage I / P so that the AC output voltage O / P falls within the predetermined voltage range. The control unit 110 sets the first relay RY1 and the second relay RY2 to conduct, transmits the AC input voltage I / P via the first relay RY1 and the third resonant circuit 108c, and then controls the fourth conversion circuit 108a to perform AC-DC conversion and generate an appropriate compensation voltage AV1 in the second capacitor C2. The control unit 110 controls the fifth conversion circuit 108b to perform DC-to-AC conversion, converting the compensation voltage AV1 into the third AC conversion signal AC3. Furthermore, it controls the transformer TR of the resonant converter 106 and the second conversion circuit 106a to perform AC-to-DC conversion, converting the third AC conversion signal AC3 into an appropriate first DC voltage DC1 and storing it in the fourth capacitor C4. The control unit 110 controls the first conversion circuit 104b (i.e., the bidirectional AC-DC converter 104) to perform DC-AC conversion, converting the first DC voltage DC1 into an appropriate AC compensation voltage Vcomp. In this embodiment, the AC compensation voltage Vcomp has a phase difference with the AC input voltage I / P (for example, the peak phase difference between the AC compensation voltage Vcomp and the AC input voltage I / P is 180 degrees), is superimposed on the AC input voltage I / P in the first resonant circuit 104a, and output to the power output terminal Pout and the neutral terminal N'. The AC output voltage O / P (i.e., the AC input voltage I / P superimposed with the AC compensation voltage Vcomp having a phase difference) is maintained within a predetermined voltage range, and the voltage adjustment function is achieved. In one embodiment, the control unit 110 installs a resonant converter 106 and converts the third AC conversion signal AC3 into a charging voltage CV1 to charge the battery 102. In one embodiment, the control unit 110 may be configured to conduct to the second relay RY2 after confirming that the AC output voltage O / P after voltage adjustment is within a predetermined voltage range.The control unit 110 may determine whether the AC input voltage I / P falls within a predetermined voltage range or voltage adjustment range based on the form of the AC input voltage I / P, such as its root mean square, peak value, and / or trough value. For example, if the root mean square of the AC input voltage I / P is 140V, the control unit 110 determines that the 140V AC input voltage I / P is outside the upper limit voltage of the predetermined voltage range (e.g., 130V), and then installs the automatic voltage adjustment circuit 108, the resonant converter 106, and the bidirectional AC-DC converter 104 to generate a corresponding AC compensation voltage Vcomp (e.g., a phase difference of 180 degrees between the AC compensation voltage Vcomp and the AC input voltage I / P), so that the adjusted AC output voltage O / P (e.g., the AC compensation voltage Vcomp superimposed on the AC input voltage I / P) falls within a predetermined voltage range (90V-130V). In another embodiment, the control unit 110 may employ other suitable signal processing methods to generate an AC output voltage O / P based on the AC compensation voltage Vcomp and the AC input voltage I / P, so that the AC output voltage O / P is within a predetermined voltage range.

[0041] In the embodiment shown in Figure 3C, if the voltage value of the AC input voltage I / P falls below the lower limit of a predetermined voltage range but is within the voltage adjustment range, the control unit 110 determines that the AC input voltage I / P is below the predetermined voltage range and executes a voltage adjustment function to boost the AC input voltage I / P so that the AC output voltage O / P falls within the predetermined voltage range. The control unit 110 conducts the first relay RY1 and the second relay RY2, transmits the AC input voltage I / P via the first relay RY1 and the third resonant circuit 108c, then controls the fourth conversion circuit 108a to perform DC-AC conversion, generating an appropriate AC compensation voltage Vcomp based on the compensation voltage AV1 of the second capacitor C2. In this embodiment, the AC compensation voltage Vcomp has a similar phase to the AC input voltage I / P (for example, the peak phase difference between the AC compensation voltage Vcomp and the AC input voltage I / P is 0 degrees), is superimposed on the AC input voltage I / P by the third resonant circuit 108c, and is output to the power output terminal Pout and the neutral terminal N', thereby achieving a voltage adjustment function so that the AC output voltage O / P (for example, the superposition of the AC compensation voltage Vcomp and the AC input voltage I / P) is within a predetermined voltage range. Furthermore, the control unit 110 controls the first conversion circuit 104b (i.e., the bidirectional AC-DC converter 104) to perform AC-DC conversion and generates a first DC voltage DC1 in the fourth capacitor C4 based on the AC output voltage O / P. The control unit 110 controls the second conversion circuit 106a of the resonant converter 106 to perform DC-AC conversion and generates a first AC conversion signal AC1 based on the first DC voltage DC1, and generates a third AC conversion signal AC3 by the transformer TR. The control unit 110 controls the fifth conversion circuit 108b to perform AC-DC conversion and generates a compensation voltage AV1 in the second capacitor C2 based on the third AC conversion signal AC3. In one embodiment, the control unit 110 installs the resonant converter 106 for DC-DC conversion and converts the first DC voltage DC1 into a charging voltage CV1 to charge the battery 102. In one embodiment, the control unit 110 may conduct to the second relay RY2 after confirming that the AC output voltage O / P after voltage adjustment is within a predetermined voltage range.The control unit 110 may determine whether the AC input voltage I / P falls within a predetermined voltage range or voltage adjustment range based on the form of the AC input voltage I / P, such as its RMS value, peak value, and / or trough value. For example, if the RMS value of the AC input voltage I / P is 70V, the control unit 110 may determine that the 70V AC input voltage I / P is below the lower limit voltage of the predetermined voltage range (e.g., 90V), and install the automatic voltage adjustment circuit 108, the resonant converter 106, and the bidirectional AC-DC converter 104 to generate a corresponding AC compensation voltage Vcomp (e.g., a phase difference of 0 degrees between the AC compensation voltage Vcomp and the AC input voltage I / P) so that the adjusted AC output voltage O / P (e.g., the superposition of the AC compensation voltage Vcomp and the AC input voltage I / P) falls within a predetermined voltage range (90V-130V). In another embodiment, the control unit 110 may employ other suitable signal processing methods to generate an AC output voltage O / P based on an AC compensation voltage Vcomp and an AC input voltage I / P, and to ensure that the AC output voltage O / P is within a predetermined voltage range.

[0042] Therefore, when the uninterruptible power supply system 100 is in the voltage adjustment mode of the embodiment shown in Figures 3B to 3C, regardless of whether the AC input voltage I / P exceeds or falls below a predetermined voltage range, the control unit 110 installs the automatic voltage adjustment circuit 108, the resonant converter 106, and the bidirectional AC-DC converter 104 to generate an appropriate AC compensation voltage Vcomp, generates an AC output voltage O / P based on the AC compensation voltage Vcomp and the AC input voltage I / P, and achieves the voltage adjustment function by ensuring that the AC output voltage O / P output by the uninterruptible power supply system 100 falls within the predetermined voltage range.

[0043] The control unit 110 is configured to operate the uninterruptible power supply system 100 in battery-powered mode if it determines that the voltage value of the AC input voltage I / P falls outside the voltage adjustment range (for example, less than 60V or more than 150V). When the uninterruptible power supply system 100 is operating in battery-powered mode, the control unit 110 deactivates the automatic voltage adjustment circuit 108, converts the discharge voltage D1 of the battery 102 into an AC output voltage O / P via the resonant converter 106 and the bidirectional AC-DC converter 104, and outputs the AC output voltage O / P to the power output terminal Pout and the neutral terminal N'.

[0044] As shown in the embodiments in Figures 1, 2A to 2B, and 3D, when the AC input voltage I / P falls outside the voltage adjustment range, the uninterruptible power supply system 100 operates in battery power supply mode, and the control unit 110 sets the second relay RY2 and the charging switch circuit 106d to conduct, sets the first relay RY1 to non-conductive, and sets the automatic voltage adjustment circuit 108 to non-operation. The control unit 110 installs a third conversion circuit 106b to perform DC-AC conversion based on the discharge voltage D1 of the battery 102, converts it to a second AC conversion signal AC2 with the second coil N2, the transformer TR generates a first AC conversion signal AC1 with the first coil N1 based on the second AC conversion signal AC2, the control unit 110 installs a second resonant circuit 106c and a second conversion circuit 106a to perform AC-DC conversion based on the first AC conversion signal AC1, generates a first DC voltage DC1 with the fourth capacitor C4, installs a first conversion circuit 104b to perform DC-AC conversion based on the first DC voltage DC1, generates an AC output voltage O / P and transmits it to the power output terminal Pout and the neutral terminal N', and ensures that the AC output voltage O / P is within a predetermined voltage range.

[0045] The predetermined voltage range and voltage adjustment range of the uninterruptible power supply system 100 may be appropriately adjusted based on various design considerations. In one embodiment, by setting the predetermined voltage range to 0, the uninterruptible power supply system 100 outputs the AC output voltage O / P after voltage adjustment of the AC input voltage I / P, thereby stabilizing the voltage of the AC output voltage O / P and improving the power factor. In this embodiment, the uninterruptible power supply system 100 operates only in voltage adjustment mode and battery power supply mode. Furthermore, the predetermined voltage range of the AC input voltage I / P and the predetermined voltage range of the AC output voltage O / P of the uninterruptible power supply system 100 may be set to be the same or different. In another embodiment, the uninterruptible power supply system 100 may be set to operate only in voltage adjustment mode and bypass output mode, or it may be set to operate only in battery power supply mode and bypass output mode.

[0046] The execution order of the above operating modes of the uninterruptible power supply system 100 is not restricted, and the control unit 110 is configured to operate the uninterruptible power supply system 100 in the appropriate operating mode based on the voltage state of the AC input voltage I / P. Furthermore, an appropriate startup procedure may be adopted when operating the uninterruptible power supply system 100. In one embodiment of the startup procedure, the battery 102 already has a certain amount of power, and the control unit 110 sets the first relay RY1 and the second relay RY2 to non-conductive, operates the resonant converter 106 and the automatic voltage adjustment circuit 108 to generate a compensation voltage AV1 with the second capacitor C2 for the discharge voltage D1 of the battery 102, and generates a first DC voltage DC1 with the fourth capacitor C4. Subsequently, the control unit 110 sets the first relay RY1 and the second relay RY2 to conduct, and operates the uninterruptible power supply system 100 in bypass output mode, voltage adjustment mode, or battery supply mode based on the state of the AC input voltage I / P.

[0047] In the above embodiment, each resonant circuit may be implemented with an appropriate architecture and circuit elements such as LC, LLC, LCL, or RLC. Each conversion circuit may be implemented in the form of an H-bridge circuit, a bridge circuit, or a conversion circuit composed of a switch and appropriate circuit elements, and the control unit 110 may be set up to cause each conversion circuit to perform voltage conversion operations such as AC to DC, DC to DC, or DC to AC using an appropriate control signal such as PWM, PFM, or PSM.

[0048] Accordingly, as can be seen from the embodiments of the present disclosure above, the resonant converter 106 and the automatic voltage regulation circuit 108 of the uninterruptible power supply system 100 of the present disclosure are shared and coupled via a transformer TR (composed of a magnetic core M, a first coil N1, a second coil N2, and a third coil N3), and the resonant converter 106 and the automatic voltage regulation circuit 108 adjust and compensate for the AC input voltage I / P, so according to the present disclosure, the cost of the number of elements can be reduced and the lifecycle of the battery 102 can be extended.

[0049] Furthermore, conventional low-frequency AVRs use metal case materials with a silicon steel magnetic core, resulting in high copper and iron losses. However, the high-frequency automatic voltage regulation circuit 108 of this disclosure uses a material with an iron magnetic core, resulting in low copper and iron losses. Therefore, according to this disclosure, losses due to copper and iron losses, as well as transportation costs, can be reduced.

[0050] Furthermore, conventional low-frequency AVRs use many relays to adjust the commercial voltage, resulting in a large volume and weight. However, the high-frequency automatic voltage regulation circuit 108 of this disclosure uses fewer relays and transistor switches to adjust the commercial voltage, resulting in a smaller volume and weight, and thus the weight and volume of the equipment can be reduced according to this disclosure.

[0051] Furthermore, the high-frequency automatic voltage regulation circuit 108 of this disclosure operates at 10 kHz or higher and simultaneously charges and discharges the battery using a bidirectional LLC all-bridge converter (i.e., a resonant converter 106), thereby reducing the volume and number of elements of the transformer and improving the overall efficiency of the system.

[0052] Furthermore, the bidirectional AC-DC converter 104 of the uninterruptible power supply system 100 can employ a totem pole power factor correction (Totem pole PFC) circuit configuration, and the resonant converter 106 of the uninterruptible power supply system 100 can employ a bidirectional LLC all-bridge converter, giving the uninterruptible power supply system 100 an active filtering or power factor correction function. Thus, the uninterruptible power supply system 100 can eliminate or reduce harmonic current pollution of power electronic equipment, maintain the stability of the sinusoidal output voltage, and improve system efficiency and stability.

[0053] The operating modes of each conversion circuit of the uninterruptible power supply system 100 in different modes can be summarized simply as shown in Figure 4. Figure 4 shows one embodiment of each operating mode of the conversion circuit of the uninterruptible power supply system. As shown in Figure 4, the uninterruptible power supply system 100 can operate in bypass output mode, step-down output voltage adjustment mode, step-up output voltage adjustment mode, and battery supply mode. When the uninterruptible power supply system 100 is in bypass output mode, the first relay RY1 and the second switch Q2 and fourth switch Q4 of the fourth conversion circuit 108a conduct, and the AC input voltage I / P is bypassed and transmitted to the first conversion circuit 104b, where the AC input voltage I / P is converted to a charging voltage CV1 and the battery 102 is charged. When the uninterruptible power supply system 100 is in step-down output voltage adjustment mode, the operation of the first conversion circuit 104b, the second conversion circuit 106a, the fourth conversion circuit 108a, and the fifth conversion circuit 108b generates an AC compensation voltage Vcomp with a large phase difference, and further adjusts the AC output voltage O / P to within a predetermined voltage range. When the uninterruptible power supply system 100 is in step-up output voltage adjustment mode, the AC output voltage O / P is boosted to within a predetermined voltage range by the AC input voltage I / P and the AC compensation voltage Vcomp with a small phase difference. When the uninterruptible power supply system 100 is in battery supply mode, the fourth conversion circuit 108a and the fifth conversion circuit 108b do not operate, and the battery 102 is discharged and converted to the AC output voltage O / P.

[0054] While the present disclosure is disclosed by the embodiments described above, these embodiments are not intended to limit the present disclosure. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. For example, the scope of protection of the present disclosure shall be defined by the subsequent claims. [Explanation of symbols]

[0055] 100: Uninterruptible Power Supply System 102:Battery 104: Bidirectional AC-DC converter 104a: 1st resonant circuit 104b: First conversion circuit 106: Resonant Converter 106a: Second conversion circuit 106b: Third conversion circuit 106c: 2nd resonant circuit 106d: Charging switch circuit 108: Automatic voltage regulation circuit 108a: Fourth conversion circuit 108b: Fifth conversion circuit 108c: Third resonant circuit 110: Control Unit I / P: AC Input Voltage O / P: AC output voltage Pin: Power input terminal Pout: Power output terminal L,L': Line terminal N,N': Neutral terminal RY1: 1st Relay RY1a: First input relay RY1b: First Neutral Relay RY2: 2nd Relay C1: First capacitor C2: Second capacitor C3: Third capacitor C4: 4th capacitor C5: Fifth capacitor L1: First inductor L2: Second inductor L3: Third inductor Q1: First switch Q2: Second switch Q3: Third switch Q4: Fourth switch Q5: Fifth switch Q6: Switch 6 Q7: The 7th switch Q8: Switch 8 Q9: Switch 9 Q10: Switch 10 Q11: Switch 11 Q12: Switch 12 Q13: Switch 13 Q14: Switch 14 Q15: Switch 15 Q16: Switch 16 Q17: Switch 17 Q18: Switch 18 Q19: Switch 19 Q20: Switch 20 Q21: Switch 21 Q22: Switch 22 M: Magnetic core N1: First coil N2: Second coil N3: Third coil DC1: First DC voltage TR: Transformers AC1: First AC conversion signal AC2: Second AC conversion signal AC3: Third AC conversion signal CV1: Charging voltage AV1: Compensation Voltage D1: Discharge voltage Vcomp: AC Compensated Voltage

Claims

1. In an uninterruptible power supply system for coupling AC input voltage and a battery, A bidirectional AC-DC converter that is coupled to a power input terminal to receive the AC input voltage and is coupled to a power output terminal to output an AC output voltage, A resonant converter comprising a magnetic core and a transformer including a first coil, a second coil, and a third coil wound around the magnetic core, coupled to the bidirectional AC / DC converter and also coupled to the battery, An automatic voltage regulation circuit is coupled to the third coil of the bidirectional AC / DC converter and the transformer, and is also coupled to the power input terminal and the power output terminal, A control unit coupled to the aforementioned bidirectional AC / DC converter, the aforementioned resonant converter, and the aforementioned automatic voltage regulation circuit, Equipped with, If the AC input voltage falls outside a predetermined voltage range but is within the voltage adjustment range, the control unit causes the automatic voltage adjustment circuit, the resonant converter, and the bidirectional AC-DC converter to generate an AC compensation voltage based on the AC input voltage, and also causes the AC output voltage to be generated at the power output terminal by superimposing the AC compensation voltage on the AC input voltage, thereby setting the AC output voltage to fall within the predetermined voltage range. If the AC input voltage falls outside the voltage adjustment range, the control unit causes the resonant converter and the bidirectional AC / DC converter to generate the AC output voltage at the power output terminal based on the discharge voltage of the battery, and is installed so that the AC output voltage is within the predetermined voltage range. The voltage adjustment range is an uninterruptible power supply system in which the maximum value is greater than the maximum value of the predetermined voltage range and the minimum value is less than the minimum value of the predetermined voltage range.

2. The uninterruptible power supply system according to claim 1, wherein when the AC input voltage is within the voltage adjustment range, the bidirectional AC-DC converter generates a first DC voltage based on the AC input voltage, and the resonant converter converts the first DC voltage into a charging voltage to charge the battery.

3. The uninterruptible power supply system according to claim 2, wherein the resonant converter generates a first AC conversion signal in the first coil based on the first DC voltage, the transformer generates a third AC conversion signal in the third coil based on the first AC conversion signal, and the automatic voltage adjustment circuit generates a compensation voltage based on the third AC conversion signal.

4. The bidirectional AC-DC converter further includes a first conversion circuit for generating the first DC voltage based on the AC input voltage, and the resonant converter is A second conversion circuit coupled to the first conversion circuit and the first coil of the transformer, which generates a first AC conversion signal in the first coil based on the first DC voltage, A third conversion circuit is coupled to the second coil of the transformer and also to the battery, It further includes, The uninterruptible power supply system according to claim 2, wherein the transformer generates a second AC conversion signal in the second coil based on the first AC conversion signal, and the third conversion circuit generates the charging voltage based on the second AC conversion signal.

5. The aforementioned automatic voltage regulation circuit is A fourth conversion circuit coupled to the power input terminal, The fourth conversion circuit and the fifth conversion circuit coupled to the third coil of the transformer, It further includes, The uninterruptible power supply system according to claim 1, wherein, when the AC input voltage is greater than the upper limit voltage of the predetermined voltage range and within the voltage adjustment range, the control unit is configured to have the fourth conversion circuit perform AC-DC conversion to generate a compensation voltage based on the AC input voltage, the fifth conversion circuit perform DC-AC conversion to generate a third AC conversion signal based on the compensation voltage, the resonant converter perform AC-DC conversion to generate a first DC voltage based on the third AC conversion signal, the bidirectional AC-DC converter perform DC-AC conversion to generate the AC compensation voltage based on the first DC voltage, and the AC compensation voltage is superimposed on the AC input voltage to generate the AC output voltage at the power output terminal, thereby ensuring that the AC output voltage is within the predetermined voltage range.

6. The uninterruptible power supply system according to claim 5, wherein the control unit is installed to cause the resonant converter to convert the third AC conversion signal into a charging voltage and charge the battery.

7. The aforementioned automatic voltage regulation circuit is A fourth conversion circuit coupled to the power input terminal, The fourth conversion circuit and the fifth conversion circuit coupled to the third coil of the transformer, It further includes, The uninterruptible power supply system according to claim 1, wherein, when the AC input voltage is smaller than the lower limit voltage of the predetermined voltage range and within the voltage adjustment range, the control unit is configured to have the fourth conversion circuit perform DC-AC conversion to generate the AC compensation voltage based on the compensation voltage, and to have the AC output voltage generated at the power output terminal by superimposing the AC compensation voltage on the AC input voltage, thereby ensuring that the AC output voltage is within the predetermined voltage range, the bidirectional AC-DC converter is configured to perform AC-DC conversion to generate a first DC voltage based on the AC output voltage, the resonant converter is configured to perform DC-AC conversion to generate a third AC conversion signal based on the first DC voltage, and the fifth conversion circuit is configured to perform AC-DC conversion to generate the compensation voltage based on the third AC conversion signal.

8. The uninterruptible power supply system according to claim 7, wherein the control unit is installed to cause the resonant converter to convert the first DC voltage into a charging voltage and charge the battery.

9. The uninterruptible power supply system according to claim 1, wherein, when the AC input voltage is within the predetermined voltage range, the control unit is configured such that the automatic voltage adjustment circuit bypasses and outputs the AC input voltage as the AC output voltage.

10. The aforementioned bidirectional AC-DC converter further includes a first conversion circuit, and the aforementioned resonant converter is The first conversion circuit and the second conversion circuit coupled to the first coil of the transformer, A third conversion circuit is coupled to the second coil of the transformer and also to the battery, It further includes, The uninterruptible power supply system according to claim 1, wherein, when the control unit determines that the AC input voltage has fallen outside the voltage adjustment range, the control unit is configured to cause the third conversion circuit to perform DC-AC conversion and generate a second AC conversion signal in the second coil based on the discharge voltage of the battery, the transformer generates a first AC conversion signal in the first coil based on the second AC conversion signal, the control unit is configured to cause the second conversion circuit to perform AC-DC conversion and generate a first DC voltage based on the first AC conversion signal, and the control unit is configured to cause the first conversion circuit to perform DC-AC conversion and generate the AC output voltage based on the first DC voltage.

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