Patent Application
20250202380
This application claims priority to Chinese Patent Application No. CN 202311719990.X, filed Dec. 14, 2023, the content of which is hereby incorporated herein by reference in its entirety.
The present inventive concept belongs to the field of power supplies, and in particular, to a power converter and an uninterruptible power supply (UPS) including the power converter.
A UPS is used to instantaneously switch to providing continuous power to a load from a backup power supply (e.g., a rechargeable battery) when a primary power supply (e.g., a municipal power grid) is not in a normal state, to protect the load from damage due to power interruption of the primary power supply. The UPS typically includes an AC-DC conversion module (rectifier) that converts an alternating current into a direct current, a DC-AC conversion module (inverter) that converts a direct current into an alternating current, a backup power supply, a DC-DC conversion module (charger) that charges the backup power supply, and a DC-DC conversion module (battery converter) that performs direct current conversion on an output voltage of the backup power supply.
When the primary power supply is faulty, the UPS switches a system from operating with the primary power supply to operating with the backup power supply. When the primary power supply resumes operation, the UPS switches the system from operating with the backup power supply to operating with the primary power supply.
With continuous development of new energy sources (e.g., lithium batteries) and with continuous expansion of application scenarios of the new energy sources, more and more UPSs use the new energy sources as backup power supplies. This also put forward higher requirements for backup power supply modes of the UPSs. A conventional UPS generally uses a dedicated circuit module to implement functions such as AC-DC conversion, DC-DC conversion, and direct current bus balancing, so that the entire UPS has a low circuit utilization, a large volume, and high costs.
Therefore, an objective of the present inventive concept is to overcome the foregoing disadvantages of the conventional technology and provide a power converter, including:
According to the power converter of the present inventive concept, preferably, the second power conversion module and the third power conversion module each include an inductor, an upper bridge arm unit, and a lower bridge arm unit, and are configured to perform DC-DC conversion through the upper bridge arm unit of the second power conversion module and the lower bridge arm unit of the third power conversion module.
According to the power converter of the present inventive concept, preferably, the first power conversion module is an I-type three-level circuit, and the second power conversion module and the third power conversion module each is a dual-boost circuit.
According to the power converter of the present inventive concept, preferably, the dual-boost circuit includes first to fourth diodes successively connected in series, first and second transistors connected in series with each other, and an inductor, where a negative electrode of the first diode is electrically connected to the positive electrode of the direct current bus, a node between a positive electrode of the first diode and a negative electrode of the second diode is electrically connected to a first terminal of the first transistor, a node between a positive electrode of the second diode and a negative electrode of the third diode is electrically connected to a first terminal of the inductor, a node between a positive electrode of the third diode and a negative electrode of the fourth diode is electrically connected to a second terminal of the second transistor, a positive electrode of the fourth diode is electrically connected to the negative electrode of the direct current bus, a node between a second terminal of the first transistor and a first terminal of the second transistor is electrically connected to the neutral line, and a second terminal of the inductor is electrically connected to the three-phase power supply or the rechargeable battery through the switch unit.
According to the power converter of the present inventive concept, preferably, the I-type three-level circuit includes first to fourth transistors successively connected in series, first and second diodes connected in series with each other, and an inductor, where a first terminal of the first transistor is electrically connected to the positive electrode of the direct current bus, a node between a second terminal of the first transistor and a first terminal of the second transistor is electrically connected to a negative electrode of the first diode, a node between a second terminal of the second transistor and a first terminal of the third transistor is electrically connected to a first terminal of the inductor, a node between a second terminal of the third transistor and a first terminal of the fourth transistor is electrically connected to a positive electrode of the second diode, a second terminal of the fourth transistor is electrically connected to the negative electrode of the direct current bus, a node between the first diode and the second diode is electrically connected to the neutral line, and a second terminal of the inductor is electrically connected to the three-phase power supply or the neutral line through the switch unit.
According to the power converter of the present inventive concept, preferably, output terminals of the first phase, the second phase, and the third phase of the three-phase power supply each is grounded through a capacitor.
According to the power converter of the present inventive concept, preferably, a fourth power conversion module is further included, capable of being configured to implement DC-DC conversion, where a first terminal of the fourth power conversion module is configured to be electrically connected to the rechargeable battery, and a second terminal of the fourth power conversion module is configured to be electrically connected to the direct current bus.
According to the power converter of the present inventive concept, preferably, the first terminal of the fourth power conversion module is electrically connected to the rechargeable battery through the switch unit.
According to the power converter of the present inventive concept, preferably, the fourth power conversion module is a bidirectional DC-DC circuit.
According to the power converter of the present inventive concept, preferably, the bidirectional DC-DC circuit includes first to third transistors and first and second inductors, where a first terminal of the first transistor is electrically connected to the positive electrode of the direct current bus, a node between a second terminal of the first transistor and a first terminal of the second transistor is electrically connected to a first terminal of the first inductor, a node between a second terminal of the second transistor and a first terminal of the third transistor is electrically connected to a first terminal of the second inductor, a second terminal of the third transistor is electrically connected to the negative electrode of the direct current bus, the first terminal of the first inductor is configured to be electrically connected to the positive electrode of the rechargeable battery, and the first terminal of the second inductor is configured to be electrically connected to the negative electrode of the rechargeable battery.
The present inventive concept further provides an uninterruptible power supply, including:
Compared with the conventional technology, the power converter of the present inventive concept multiplexes rectifier bridge arms as a battery conversion bridge arm and a balance bridge arm, which greatly improves circuit utilization and battery power supply efficiency, reduces the volume of the power converter, and reduces costs.
The following further describes the embodiments of the present inventive concept with reference to the accompanying drawings, where:
To make the objectives, technical solutions, and advantages of the present inventive concept clearer, the following further describes the present inventive concept in detail through the embodiments with reference to the accompanying drawings. It should be understood that the embodiments described herein are only used to explain the present inventive concept, but are not intended to limit the present inventive concept.
Referring to
As shown in
The dual-boost circuit of the second bridge arm L2 includes first to fourth diodes D1b-D4b successively connected in series, first and second transistors T1b and T2b connected in series with each other, and a second inductor Lb, where a negative electrode of the first diode D1b is electrically connected to the positive direct current bus DC+, a positive electrode of the first diode D1b is electrically connected to a first terminal of the first transistor T1b and a negative electrode of the second diode D2b, a positive electrode of the second diode D2b is electrically connected to a first terminal of the second inductor Lb and a negative electrode of the third diode D3b, a positive electrode of the third diode D3b is electrically connected to a second terminal of the second transistor T2b and a negative electrode of the fourth diode D4b, a positive electrode of the fourth diode D4b is electrically connected to the negative direct current bus DC−, a node between a second terminal of the first transistor T1b and a first terminal of the second transistor T2b is grounded, and a second terminal of the second inductor Lb is connected to a second phase S of the three-phase alternating current power supply AC through a relay K2, and is connected to the positive electrode of the battery BAT through a relay K4. Likewise, anti-parallel diodes are respectively built in the first transistor T1b and the second transistor T2b. It is clear from
The dual-boost circuit of the third bridge arm L3 includes first to fourth diodes D1c-D4c successively connected in series, first and second transistors T1c and T2c connected in series with each other, and a third inductor Lc, where a negative electrode of the first diode D1c is electrically connected to the positive direct current bus DC+, a positive electrode of the first diode D1c is electrically connected to a first terminal of the first transistor T1c and a negative electrode of the second diode D2c, a positive electrode of the second diode D2c is electrically connected to a first terminal of the third inductor Lc and a negative electrode of the third diode D3c, a positive electrode of the third diode D3c is electrically connected to a second terminal of the second transistor T2c and a negative electrode of the fourth diode D4c, a positive electrode of the fourth diode D4c is electrically connected to the negative direct current bus DC−, a node between a second terminal of the first transistor T1c and a first terminal of the second transistor T2c is grounded, and a second terminal of the third inductor Lc is connected to a third phase T of the three-phase alternating current power supply AC through a relay K3, and is connected to the negative electrode of the battery BAT through a relay K6. Likewise, anti-parallel diodes are respectively built in the first transistor T1c and the second transistor T2c. Similarly, the diodes D1c and D2c and the transistor T1c constitute an upper bridge arm unit of the third bridge arm L3, and the diodes D3c and D4c and the transistor T2c constitute a lower bridge arm unit of the third bridge arm L3.
The bidirectional DC/DC conversion circuit of the fourth bridge arm L4 includes first to third transistors T1-T3, and first and second inductors Ld and Le, where a first terminal of the first transistor T1 is electrically connected to the positive direct current bus DC+, a node between a second terminal of the first transistor T1 and a first terminal of the second transistor T2 is connected to a first terminal of the first inductor Ld, a node between a second terminal of the second transistor T2 and a first terminal of the third transistor T3 is connected to a first terminal of the second inductor Le, a second terminal of the third transistor T3 is electrically connected to the negative direct current bus DC−, a second terminal of the first inductor Ld is electrically connected to the positive electrode of the battery BAT through a relay K5, a second terminal of the second inductor Le is electrically connected to the negative electrode of the battery BAT through a relay K7, and a filter capacitor C4 is connected in parallel between two electrodes of the battery BAT. Likewise, anti-parallel diodes are respectively built in the first to third transistors T1-T3.
Capacitors C2 and C3 that are connected in series with each other are connected between output terminals of the second phase S and the third phase T of the three-phase alternating current power supply AC, and a node between the two capacitors is grounded.
A first capacitor Cp and a second capacitor Cn are connected in series between the positive direct current bus DC+ and the negative direct current bus DC−, and a node between the first capacitor Cp and the second capacitor Cn is grounded.
In the embodiment of the present inventive concept, the dual-boost circuits of the second bridge arm L2 and the third bridge arm L3 use fewer transistors than the I-type three-level circuit of the first bridge arm L1, thereby reducing the volume and the costs.
The following discusses, with reference to
Mains supply mode (the mains supply operates normally): As shown in
When a mains voltage is in a positive half cycle, particularly, a voltage of each phase of the three-phase alternating current power supply AC is in the positive half cycle:
For the first rectifier bridge arm L1, when T3a is switched on and T1a, T2a, and T4a are switched off, the first inductor La stores energy. A current path is: AC (R)→K1→La→T3a→D2a→neutral line N (grounded), as shown by solid line arrows in
After energy storage is completed, T1a, T2a, T3a, and T4a are switched off, and the inductor La releases energy to the direct current link capacitors Cp and Cn. A current path is: La→D (T2a)→D (T1a)→DC+→Cp→neutral line N (grounded), as shown by dashed line arrows in
For the second rectifier bridge arm L2, when T1b is switched on and T2b is switched off, the second inductor Lb stores energy. A current path is: AC(S)→K2→Lb→D2b→T1b→neutral line N (grounded).
After energy storage is completed, T1b and T2b are switched off, and the inductor Lb releases energy to the direct current link capacitors Cp and Cn. A current path is: Lb→D2b→D1b→DC+→Cp→neutral line N (grounded). This process is also a process of continuation of an inductor current after the transistors are switched off.
Similarly, for the third bridge arm L3, when T1c is switched on and T2c is switched off, the third inductor Lc stores energy. A current path is: AC (T)→K3→Lc→D2c→T1c→neutral line N (grounded).
After energy storage is completed, T1c and T2c are switched off, and the inductor Lc releases energy to the direct current link capacitors Cp and Cn. A current path is: Lc→D2c→D1c→DC+→Cp→neutral line N (grounded). This process is a process of continuation of an inductor current after the transistors are switched off. For clarity, current paths for the second bridge arm L2 and the third bridge arm L3 are not shown in
When the mains voltage is in a negative half cycle, particularly, the voltage of each phase of the three-phase alternating current power supply AC is in the negative half cycle:
For the first rectifier bridge arm L1, when T2a is switched on and T1a, T3a, and T4a are switched off, the first inductor La stores energy. A current path is: neutral line N (grounded)→D1a→T2a→La→K1→AC (R).
After energy storage is completed, when T1a, T2a, T3a, and T4a are switched off, the inductor La releases energy to the direct current link capacitors Cp and Cn. A current path is: neutral line N (grounded)→Cn→DC−→D (T4a)→D (T3a)→La. This process is actually a process of continuation of an inductor current after the transistors are switched off.
For the second rectifier bridge arm L2, when T2b is switched on and T1b is switched off, the second inductor Lb stores energy. A current path is: neutral line N (grounded)→T2b→D3b→Lb→K2→AC(S).
After energy storage is completed, T1b and T2b are switched off, and the inductor Lb releases energy to the direct current link capacitors Cp and Cn. A current path is: neutral line N (grounded)→Cn→DC−→D4b→D3b→Lb. This process is also a process of continuation of an inductor current after the transistors are switched off.
Similarly, for the third bridge arm L3, when T2c is switched on and T1c is switched off, the third inductor Lc stores energy. A current path is: neutral line N (grounded)→T2c→D3c→Lc→K3→AC (T).
After energy storage is completed, T1c and T2c are switched off, and the inductor Lc releases energy to the direct current link capacitors Cp and Cn. A current path is: neutral line N (grounded)→Cn→DC−→D4c→D3c→Lc. This process is also a process of continuation of an inductor current after the transistors are switched off.
In addition, in the mains supply mode, when the battery BAT is underpowered, the relays K5 and K7 are switched on, and the direct current buses DC+ and DC-charge the battery BAT. When the transistors T1 and T3 are switched on and the transistor T2 is switched off, the direct current buses store energy for the inductors Ld and Le, and a current path is: DC+→T1→Ld→K5→BAT→K7→Le→T3→DC−. After energy storage is completed, the transistors T1 and T3 are switched off, the transistor T2 is switched on, the inductors Ld and Le release energy with a current path Ld→K5→BAT→K7→Le→T2, to continue charging the battery BAT. This process is also a process of continuation of an inductor current.
In a battery mode (when the mains supply is faulty), the power converter is disconnected from the mains supply AC and is powered only by the battery BAT. As shown in
When T1b and T2c are switched on and T2b and T1c are switched off, the inductors Lb and Lc store energy, and a current path is:
BAT+→K4→Lb→D2b→T1b→T2c→D3c→Lc→K6→BAT−, as shown by solid line arrows in
When T1b, T2b, T1c, and T2c are all switched off, the inductors Lb and Lc release energy, and a current path is:
BAT+→K4→Lb→D2b→D1b→DC+→Cp→Cn→DC−→D4c→D3c→Lc→K6→BAT−, as shown by dashed line arrows in
In this way, the battery BAT supplies power to the direct current buses. The second bridge arm L2 and the third bridge arm L3 jointly (for example, through the upper bridge arm unit of the second bridge arm L2 and the lower bridge arm unit of the third bridge arm L3) implement DC-DC conversion, thereby improving circuit utilization.
Generally, all loads cannot be completely balanced. Especially, for a three-phase power supply, if only single-phase loads are connected, the system can become very unbalanced. In this case, it is necessary to control balance of the positive and negative direct current buses. In the battery mode, preferably, the I-type three-level circuit of the first bridge arm L1 is used as a balance branch, transistors and alternating conduction thereof of the first bridge arm L1 are controlled, so that the balance of the direct current buses can be implemented. Specifically, if a voltage of the capacitor Cp is higher than that of the capacitor Cn, when the transistors T1a and T2a are switched on and the transistors T3a and T4a are switched off, the inductor La stores energy, and a current path is: DC+→T1a→T2a→La→K8→neutral line (ground wire)→Cp, as shown by solid line arrows in
In addition, considering that switches are needed for multiplexing rectifier bridge arms as a battery conversion bridge arm, this takes time, typically switching time on the order of 10 ms, for example, 20 ms. To ensure continuity of power supply, in the battery mode, the battery further performs DC-DC conversion through the fourth bridge arm L4 to supply power to the direct current buses. Specifically, the relays K5 and K7 are switched on.
When T1 and T3 are switched off and T2 is switched on, the inductors Ld and Le store energy, and a current path is: BAT+→K5→Ld→T2→Le→K7→BAT−.
When T2 is switched off and T1 and T3 are switched on, the capacitor C4 and the inductors Ld and Le release energy, and a current path is: BAT+→K5→Ld→D (T1)→DC+→Cp→Cn→DC−→D (T3)→Le→K7→BAT−.
In this way, the battery BAT supplies power to the direct current buses through the second bridge arm, the third bridge arm, and the fourth bridge arm together, thereby greatly improving battery power supply efficiency, reducing a full load rate of a battery bridge arm, generally requiring only a full load rate design of about 50%, and significantly reducing the costs and volume. Preferably, in this operating mode, the fourth bridge arm is interleaved in parallel with a multiplexed battery bridge arm formed by the second bridge arm and the third bridge arm, thereby reducing ripples. More preferably, another battery bridge arm is further disposed in the power converter in the embodiment of the present inventive concept. As shown by a dashed line below the T phase in
In addition, the power converter in the embodiment of the present inventive concept further resolves a disadvantage that a battery of a dual-boost circuit in the conventional technology needs to have a neutral line. In the dual-boost circuit in the conventional technology, a positive electrode and a negative electrode of the battery are respectively independent of each other during discharging. To balance positive and negative direct current buses in the battery mode, a neutral line needs to be led out at a middle point of a battery pack, a corresponding quantity of batteries connected in series must be an even number, and a quantity of transistors must also be increased. In the embodiment of the present inventive concept, the first bridge arm L1 is multiplexed as a balance bridge arm to balance the positive and negative direct current buses in the battery mode, there is no requirement on the quantity of batteries, and field application is not limited, thereby reducing costs.
Another embodiment of the present inventive concept provides a UPS. Referring to a structural block diagram of the UPS in this embodiment shown in
Another embodiment of the present inventive concept provides another UPS. Referring to a structural block diagram of the UPS in this embodiment shown in
The power converter in the embodiments of the present inventive concept can implement different operating modes by controlling switches. Therefore, the UPS in the embodiments of the present inventive concept can directly convert a battery output by rectifier bridge arms or a battery conversion bridge arm to supply power to the direct current bus at low load, and convert the battery output by both the rectifier bridge arms and the battery conversion bridge arm to supply power to the direct current bus at high load. Therefore, the UPS in the present inventive concept has a wider range of application scenarios.
According to other embodiments of the present inventive concept, a relay may be replaced with a well-known switching element in the art, for example, a mechanical switch, a circuit breaker, or the like. In addition, switch components (K1, K8), (K2, K4), and (K3, K6) may be replaced with single-pole double-throw switches.
According to other embodiments of the present inventive concept, the transistor is an IGBT, a MOSFET, or the like.
According to other embodiments of the present inventive concept, the first to the third switch modules constitute a switch unit.
Although the present inventive concept has been described by using embodiments, the present inventive concept is not limited to the embodiments described herein, and includes various changes and variations without departing from the scope of the present inventive concept.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202311719990.X | Dec 2023 | CN | national |
