Power converter and UPS (Uninterrupted Power Supply) comprising same

Abstract

The invention provides a power converter and a UPS comprising the power converter, the power converter comprising: a first power conversion module comprising a first bridge arm and a second bridge arm, a first end of the first power conversion module being configured to be electrically connectable to a mains supply and / or a rechargeable battery, and a second end being configured to be electrically connectable to a DC bus; the second power conversion module comprises a third bridge arm and a fourth bridge arm, the first end of the second power conversion module is configured to be electrically connected to the mains supply and / or the rechargeable battery, and the second end of the second power conversion module is configured to be electrically connected to the direct current bus; and the switch module is configured to enable the first end of the first power conversion module and the first end of the second power conversion module to be selectively and electrically connected to the mains supply and / or the rechargeable battery, the first power conversion module, the second power conversion module and the switch module are configured to charge the rechargeable battery from the direct current bus through the first bridge arm and the fourth bridge arm.

Description

Technical Field

[0001] The invention belongs to the field of electric power supply, and in particular relates to a power converter and an uninterruptible power supply (UPS) comprising the power converter. Background Art

[0002] UPS is used to instantly switch to a backup power source (such as a rechargeable battery) to provide continuous power to the load when the main power source (such as the city grid) is not in normal power supply state, so as to protect the load from damage caused by power outage of the main power source. UPS usually includes an AC-DC conversion module (rectifier) ​​that converts AC power into DC power, a DC-AC conversion module (inverter) that converts DC power into AC power, a backup power source, and a DC-DC conversion module (charger) that charges the backup power source.

[0003] When the main power fails, the UPS switches the system from main power operation to backup power operation, and when the main power starts working again, it switches from backup power operation to main power operation. Summary of the invention

[0004] Therefore, the object of the present invention is to reduce cost and optimize space, and provide a power converter, comprising:

[0005] A first power conversion module, comprising a first bridge arm and a second bridge arm, wherein a first end of the first power conversion module is configured to be electrically connected to a mains power supply and / or a rechargeable battery, and a second end of the first power conversion module is configured to be electrically connected to a DC bus;

[0006] a second power conversion module, comprising a third bridge arm and a fourth bridge arm, wherein a first end of the second power conversion module is configured to be electrically connected to a mains power supply and / or a rechargeable battery, and a second end of the second power conversion module is configured to be electrically connected to a DC bus; and

[0007] a switch module, which is configured to selectively electrically connect the first end of the first power conversion module and the first end of the second power conversion module to the mains and / or a rechargeable battery,

[0008] The first power conversion module, the second power conversion module and the switch module are configured to charge the rechargeable battery from the DC bus through the first bridge arm and the fourth bridge arm.

[0009] According to the power converter of the present invention, preferably, the first power conversion module, the second power conversion module and the switch module are configured to convert the first phase of the AC power into DC power and provide it to the DC bus through the second bridge arm, and convert the second phase of the AC power into DC power and provide it to the DC bus through the third bridge arm.

[0010] According to the power converter of the present invention, preferably, the switch module includes a first switch component, a second switch component, a third switch component and a fourth switch component corresponding to the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm, respectively, and are respectively configured so that the first ends of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are selectively connected to the mains or a rechargeable battery.

[0011] According to the power converter of the present invention, preferably, the first end of the first power conversion module includes a first sub-terminal and a second sub-terminal, and the first end of the second power conversion module includes a third sub-terminal and a fourth sub-terminal, wherein the first sub-terminal is electrically connected to the first switch component, the second sub-terminal is electrically connected to the second switch component, the third sub-terminal is electrically connected to the third switch component, and the fourth sub-terminal is electrically connected to the fourth switch component.

[0012] According to the power converter of the present invention, preferably, the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm respectively include an inductor, a first switching transistor and a second switching transistor, wherein the first end of the first switching transistor and the second end of the second switching transistor constitute the output end of the bridge arm, the second end of the first switching transistor is electrically connected to the first end of the second switching transistor, the first end of the inductor is electrically connected to the node between the first switching transistor and the second switching transistor, and the second end of the inductor is electrically connected to the corresponding switching component.

[0013] According to the power converter of the present invention, preferably, two capacitors connected in series are respectively arranged between the positive electrode and the negative electrode of the DC bus, and a node between the two capacitors is grounded.

[0014] According to the power converter of the present invention, preferably, it also includes a third power conversion module, including a fifth bridge arm and a sixth bridge arm, and the first end of the third power conversion module is configured to be electrically connected to the mains, and the second end is configured to be electrically connected to the DC bus.

[0015] The power converter according to the present invention preferably includes the following working modes:

[0016] a rectification mode, wherein the switch module is configured such that the first sub-terminal, the second sub-terminal, the third sub-terminal and the fourth sub-terminal are all electrically connected to the mains; and

[0017] The rectifying-charging mode is configured such that the first sub-terminal and the fourth sub-terminal are electrically connected to a rechargeable battery, and the second sub-terminal and the third sub-terminal are electrically connected to the mains.

[0018] The present invention also provides an uninterruptible power supply, comprising:

[0019] A power converter according to the present invention;

[0020] an inverter electrically connected to a DC bus of the power converter;

[0021] a rechargeable battery, a charging terminal of which is electrically connected to the switch module of the power converter; and

[0022] The DC-DC converter is configured to convert the output voltage of the rechargeable battery and provide the converted voltage to the inverter.

[0023] The uninterruptible power supply according to the present invention preferably further comprises a charger electrically connected to the charging terminal of the rechargeable battery.

[0024] Compared with the prior art, the power converter of the present invention can improve the charging capacity of the UPS and reduce the cost and volume of the UPS. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0026] Figure 1 is a schematic block diagram of a power converter according to an embodiment of the present invention;

[0027] Figure 2 A circuit topology of a power converter according to an embodiment of the present invention;

[0028] Figure 3 The current loop of the power converter during inductor charging according to one embodiment of the present invention is shown;

[0029] Figure 4 The current loop of the power converter during inductor discharge according to one embodiment of the present invention is shown;

[0030] Figure 5 and Figure 6 The battery voltage and inductor current curves of the simulation experiment during low current and high current charging are shown respectively;

[0031] Figure 7 is a structural block diagram of a UPS according to an embodiment of the present invention; and

[0032] Figure 8 FIG. 4 is a structural block diagram of a UPS according to another embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail by specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Figure 1 A schematic block diagram of a power converter of an embodiment of the present invention is shown, wherein the power converter includes a first power conversion module 101, a second power conversion module 102 and a switch module 103, wherein the switch module 103 is arranged between the first end of the first power conversion module 101 and the second power conversion module 102 and the mains AC and the rechargeable battery BT, and is configured so that the first end T1 of the first power conversion module 101 and the first end T2 of the second power conversion module 102 are selectively electrically connected to the mains AC and / or the rechargeable battery BT, the second end T3 of the first power conversion module 101 is configured to be electrically connected to the DC bus DC, and the second end T4 of the second power conversion module 102 is configured to be electrically connected to the DC bus DC. It can be understood by those skilled in the art that the DC bus connected to the T3 and T4 ends can be the same DC bus or different DC buses. Specifically, the first power conversion module 101 and the second power conversion module 102 respectively include two power conversion bridge arms. The first power conversion module 101, the second power conversion module 102 and the switch module 103 are configured to implement different working modes, including a rectification mode, a charging mode and a rectification-charging mode. Specifically, when it is not necessary to charge the battery, the switch logic of the switch module 103 and the working logic of the power conversion modules 101 and 102 are controlled so that the first end T1 of the first power conversion module 101 and the first end T2 of the second power conversion module 102 are both powered by the mains, and are respectively provided to the T3 and T4 ends after AC-DC conversion, and then the load is powered. When it is necessary to charge the battery, the switch logic of the switch module 103 and the working logic of the power conversion modules 101 and 102 are controlled so that the rechargeable battery is charged from the DC bus DC through the first bridge arm of the power conversion module 101 and the second bridge arm of the power conversion module 102. Preferably, the DC bus can also be powered by the mains through the second bridge arm of the power conversion module 101 and the first bridge arm of the power conversion module 102.

[0035] See also Figure 2The circuit topology of a power converter according to an embodiment of the present invention is shown, which includes a first phase S and a second phase T, wherein the first phase S and the second phase T respectively include two bridge arms X and Y connected in parallel with each other, and the first bridge arm X of the first phase S includes a first inductor L1s, a first switching transistor Q1s and a second switching transistor Q2s, wherein the first end of the first switching transistor Q1s is electrically connected to the positive DC bus DC+, the second end of the first switching transistor Q1s is electrically connected to the first end of the second switching transistor Q2s, the second end of the second switching transistor Q2s is electrically connected to the negative DC bus DC-, the first end of the first inductor L1s is electrically connected to the node between the first switching transistor Q1s and the second switching transistor Q2s, the second end of the first inductor L1s is electrically connected to the positive electrode of the rechargeable battery BT1 through the first relay R1s, and is also electrically connected to the mains AC through the second relay R2s, a first capacitor Cp and a second capacitor Cn are connected in series between the positive DC bus DC+ and the negative DC bus DC-, and a node DC-mid between the first capacitor Cp and the second capacitor Cn is grounded. Similarly, the second bridge arm Y of the first phase S includes a second inductor L2s, a third switching transistor Q3s and a fourth switching transistor Q4s, wherein a first end of the third switching transistor Q3s is electrically connected to the positive DC bus DC+, a second end of the third switching transistor Q3s is electrically connected to the first end of the fourth switching transistor Q4s, a second end of the fourth switching transistor Q4s is electrically connected to the negative DC bus DC-, a first end of the second inductor L2s is electrically connected to a node between the third switching transistor Q3s and the fourth switching transistor Q4s, a second end of the second inductor L1s is electrically connected to the positive electrode of the rechargeable battery BT1 through the third relay R3s, and is also electrically connected to the AC power AC through the fourth relay R4s.

[0036] The second phase T has the same design as the first phase S. Specifically, the first bridge arm X of the second phase T includes a first inductor L1t, a first switching transistor Q1t, and a second switching transistor Q2t, wherein a first end of the first switching transistor Q1t is electrically connected to the positive DC bus DC+, a second end of the first switching transistor Q1t is electrically connected to a first end of the second switching transistor Q2t, a second end of the second switching transistor Q2t is electrically connected to a negative DC bus DC-, a first end of the first inductor L1t is electrically connected to a node between the first switching transistor Q1t and the second switching transistor Q2t, a second end of the first inductor L1t is electrically connected to the positive electrode of the rechargeable battery BT1 through a first relay R1t, and is also electrically connected to the mains AC through a second relay R2t, a first capacitor Cp and a second capacitor Cn are connected in series between the positive DC bus DC+ and the negative DC bus DC-, and a node DC-mid between the first capacitor Cp and the second capacitor Cn is grounded. Similarly, the second bridge arm Y of the second phase T includes a second inductor L2t, a third switching transistor Q3t and a fourth switching transistor Q4t, wherein a first end of the third switching transistor Q3t is electrically connected to the positive DC bus DC+, a second end of the third switching transistor Q3t is electrically connected to the first end of the fourth switching transistor Q4t, a second end of the fourth switching transistor Q4t is electrically connected to the negative DC bus DC-, a first end of the second inductor L2t is electrically connected to a node between the third switching transistor Q3t and the fourth switching transistor Q4t, a second end of the second inductor L1t is electrically connected to the positive electrode of the rechargeable battery BT1 through the third relay R3t, and is also electrically connected to the mains AC through the fourth relay R4t.

[0037] In this embodiment, relays R1s, R3s, R2t and R4t are turned on, and relays R2s, R4s, R1t and R3t are turned off. By controlling the switching transistors Q1s and Q4t to be turned on, and the switching transistors Q2s and Q3t to be turned off, the current loop is: DC-mid→Cp→DC+→Q1s→L1s→R1s→BT1→R4t→L2t→Q4t→DC-→Cn→DC-mid. Figure 3 The current loop is shown by the arrow. It can be seen that in this case, the DC-DC conversion is realized by the loop formed by the first bridge arm X of the first phase S and the second bridge arm Y of the second phase T, and energy is stored in the inductors L1s and L2t, and the battery BT1 is charged at the same time. At the same time, in this embodiment, the second bridge arm Y of the first phase S and the first bridge arm X of the second phase T are both connected to the AC power and disconnected from the battery BT1. Therefore, these two bridge arms constitute the rectifier bridge arm, and the AC-DC conversion is realized by supplying power from the AC power to the DC bus. The rectification principle of the rectifier bridge arm is the same as the rectification principle of the prior art, which will not be repeated here.

[0038] When the inductors L1s and L2t store enough energy, the switch transistors Q1s and Q4T are turned off and the switch transistors Q2s and Q3t are turned on. At this time, the current loop is: DC-mid→Cn→DC-→Q2s→L1s→R1s→BT1→R4t→L2t→Q3t→DC+→Cp→DC-mid. Figure 4 The current loop is shown by the arrow. It can be seen that in this case, the DC-DC conversion is realized by the loop formed by the first bridge arm X of the first phase S and the second bridge arm Y of the second phase T, and the inductance L1s of the first bridge arm X of the first phase S and the inductance L2t of the second bridge arm Y of the second phase T release energy, thereby charging the battery BT1. At the same time, the second bridge arm Y of the first phase S and the first bridge arm X of the second phase T form a conventional rectifier bridge arm to realize AC-DC conversion.

[0039] In this embodiment, when the battery BT1 needs to be charged, a part of the bridge arm of the power converter realizes the rectification function, and another part of the bridge arm realizes the reverse charging function.

[0040] When the battery BT1 is fully charged, the relays R1s and R4t can be controlled to be disconnected, and the relays R2s and R3t can be controlled to be turned on, so that the entire power converter can achieve two-phase dual-bridge arm rectification, thereby improving the rectification capacity of the entire power converter.

[0041] In order to demonstrate the effect of the present invention, the inventor simulated the power converter of the above embodiment. Figure 5 and Figure 6 The battery voltage and inductor circuit curves of the simulation experiment, the battery voltage and inductor current when charging with a small current are as follows Figure 5 As shown in Figure 2, the battery voltage and inductor current during high current charging are as follows: Figure 6 As shown, it can be seen that the power converter of the embodiment of the present invention can achieve a stable voltage across the battery, that is, achieve continuous and effective charging of the battery.

[0042] According to another embodiment of the present invention, the power converter further includes a third phase R, and the circuit topology of the third phase R is the same as the circuit topology of the first phase S and the second phase T in the aforementioned embodiment, including two bridge arms X and Y connected in parallel to each other, and the specific details are not repeated. Those skilled in the art can understand that in this embodiment, when the battery does not need to be charged, the first phase S, the second phase T and the third phase R all work in the rectification mode to convert the mains power into direct current; when the battery needs to be charged, one bridge arm is selected from any two phases of the first phase S, the second phase T and the third phase R to be electrically connected to the battery so as to charge the battery, and specifically the current flow direction is the same as in the aforementioned embodiment, and the remaining bridge arms are used for rectification.

[0043] Another embodiment of the present invention provides a UPS, see Figure 7The structural block diagram of the UPS of this embodiment shown includes a power converter 701, an inverter 702, a DC-DC conversion module 703 and a battery module 704. Compared with the traditional UPS, the power converter 701 of the UPS of this embodiment can charge the battery module 704 while realizing rectification, omitting the dedicated battery charging module, reducing the size of the UPS and saving costs.

[0044] Another embodiment of the present invention provides another UPS, see Figure 8 The structural block diagram of the UPS of this embodiment shown includes a power converter 701, an inverter 702, a DC-DC conversion module 703, a battery module 704 and a charging module 705. Compared with the traditional UPS, the UPS of this embodiment can use the charging module 705 and the power converter 701 to charge the battery module 704 at the same time, thereby improving the charging capacity, and is particularly suitable for scenarios with relatively high charging power requirements and relatively light loads.

[0045] Since the power converter of an embodiment of the present invention can realize different working modes by controlling the relay, the UPS according to the embodiment of the present invention can adopt the full rectification mode of the power converter when high charging power is not required to improve the load working capacity; and adopt the rectification + charging mode of the power converter when high charging power is required to improve the charging capacity. Therefore, the application scenarios of the UPS of the present invention are more extensive.

[0046] According to other embodiments of the present invention, the relay may be replaced by a known switch element, including a mechanical switch, a circuit breaker, etc. In addition, each set of switches, such as (R1s, R2s), (R3s, Relay4s), (R1t, R2t) and (R3t, R4t), does not necessarily include two separate switches, and may be replaced by a single-pole double-throw switch.

[0047] According to other embodiments of the present invention, the switch transistor is an IGBT, a MOSFET or the like.

[0048] According to other embodiments of the present invention, the structure of each bridge arm is not limited to the half-bridge form of the aforementioned embodiment, and may be a rectifier bridge form known in the art.

[0049] Although the present invention has been described through preferred embodiments, the present invention is not limited to the embodiments described herein but includes various changes and modifications that may be made without departing from the scope of the present invention.

Claims

1. A power converter, comprising: A first power conversion module, comprising a first bridge arm and a second bridge arm, wherein a first end of the first power conversion module is configured to be electrically connected to a mains power supply and / or a rechargeable battery, and a second end of the first power conversion module is configured to be electrically connected to a DC bus; A second power conversion module, comprising a third bridge arm and a fourth bridge arm, wherein a first end of the second power conversion module is configured to be electrically connected to a mains power supply and / or a rechargeable battery, and a second end of the second power conversion module is configured to be electrically connected to a DC bus; and a switch module, which is configured to selectively electrically connect the first end of the first power conversion module and the first end of the second power conversion module to the mains and / or a rechargeable battery, The first power conversion module, the second power conversion module and the switch module are configured to charge the rechargeable battery from the DC bus through the first bridge arm and the fourth bridge arm.

2. The power converter according to claim 1, wherein: The first power conversion module, the second power conversion module and the switch module are configured to convert the first phase of the AC power into DC power through the second bridge arm and provide it to the DC bus, and to convert the second phase of the AC power into DC power through the third bridge arm and provide it to the DC bus.

3. The power converter according to claim 2, wherein: The switch module includes a first switch component, a second switch component, a third switch component and a fourth switch component corresponding to the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm respectively, and is respectively configured so that the first ends of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are selectively connected to the mains or a rechargeable battery.

4. The power converter according to claim 3, wherein: The first end of the first power conversion module includes a first sub-terminal and a second sub-terminal, and the first end of the second power conversion module includes a third sub-terminal and a fourth sub-terminal, wherein the first sub-terminal is electrically connected to the first switch component, the second sub-terminal is electrically connected to the second switch component, the third sub-terminal is electrically connected to the third switch component, and the fourth sub-terminal is electrically connected to the fourth switch component.

5. The power converter according to claim 3, wherein: The first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm respectively include an inductor, a first switching transistor and a second switching transistor, wherein the first end of the first switching transistor and the second end of the second switching transistor constitute the output end of the bridge arm, the second end of the first switching transistor is electrically connected to the first end of the second switching transistor, the first end of the inductor is electrically connected to a node between the first switching transistor and the second switching transistor, and the second end of the inductor is electrically connected to a corresponding switch component.

6. The power converter according to claim 1, wherein: Two capacitors connected in series are respectively arranged between the positive electrode and the negative electrode of the DC bus, and a node between the two capacitors is grounded.

7. The power converter according to any one of claims 4-6 further includes a third power conversion module, including a fifth bridge arm and a sixth bridge arm, wherein the first end of the third power conversion module is configured to be electrically connected to the AC power supply, and the second end is configured to be electrically connected to a DC bus.

8. The power converter according to claim 4-6, comprising the following working modes: Rectification mode, where The switch module is configured so that the first sub-terminal, the second sub-terminal, the third sub-terminal and the fourth sub-terminal are all electrically connected to the mains; and The rectifying-charging mode is configured such that the first sub-terminal and the fourth sub-terminal are electrically connected to a rechargeable battery, and the second sub-terminal and the third sub-terminal are electrically connected to the mains.

9. An uninterruptible power supply comprising: A power converter according to any one of claims 1 to 8; an inverter electrically connected to a DC bus of the power converter; A rechargeable battery, a charging terminal of which is electrically connected to the switch module of the power converter; and The DC-DC converter is configured to convert the output voltage of the rechargeable battery and provide the converted voltage to the inverter.

10. The uninterruptible power supply of claim 9, further comprising a charger electrically connected to a charging terminal of the rechargeable battery.

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