WO2021232785A1

WO2021232785A1 - Three-bridge arm topology apparatus, control method, and uninterrupted power supply system

Info

Publication number: WO2021232785A1
Application number: PCT/CN2020/138679
Authority: WO
Inventors: 罗峰
Original assignee: 广州视源电子科技股份有限公司; 广州视琨电子科技有限公司
Priority date: 2020-05-22
Filing date: 2020-12-23
Publication date: 2021-11-25
Also published as: CN111478408A

Abstract

A three-bridge arm topology apparatus, a control method, and an uninterrupted power supply system. By multiplexing a voltage conversion circuit, the three-bridge arm topology apparatus can implement a charging function of a battery pack without additionally providing a charger. In addition, whether in a mains power supply mode or a battery power supply mode, both the voltage conversion circuit and a three-bridge arm conversion circuit participate in the work, i.e. all devices of the three-bridge arm topology apparatus participate in the work. When the three-bridge arm topology apparatus is applied to a battery low-voltage large-current uninterrupted power supply system, the device multiplexing rate of the system can be improved, the device design redundancy is avoided, and thus the costs of the battery low-voltage large-current uninterrupted power supply system are reduced.

Description

Three bridge arm topology device, control method, and uninterruptible power supply system

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 202010444170.4 on May 22, 2020. The entire content of this application is incorporated into this application by reference.

Technical field

This application relates to uninterruptible power supply technology, and in particular to a three-leg topology device, a control method, and an uninterruptible power supply system.

Background technique

An online uninterrupted power supply (Uninterrupted Power Supply, UPS for short) system refers to a UPS system in which the AC voltage used by the load passes through the inverter circuit regardless of whether the grid voltage is normal or not. According to power division, online UPS systems are divided into online medium and small power UPS systems and online high power UPS systems. On-line medium and small power UPS systems usually refer to on-line UPS systems with power between 1 kW and 3 kW.

The battery low-voltage high-current UPS system is an online medium and small power UPS system. The battery pack of the UPS system has a small number of batteries. When the battery pack is used to supply power to the load, the battery pack can output low voltage and high current Electrical energy. Due to the small number of battery cells in the battery pack used in the battery low-voltage high-current UPS system, the battery low-voltage high-current UPS system is widely used in the field of online medium and small power UPS. However, the device reuse rate of the existing battery low-voltage and high-current UPS system is low, resulting in high cost of the battery low-voltage and high-current UPS system.

Summary of the invention

The present application provides a three-arm topology device, a control method, and an uninterruptible power supply system, which are used to solve the technical problem of the low device reuse rate of the existing battery low-voltage and high-current UPS system.

In the first aspect, the present application provides a three-leg topology device, the three-leg topology device includes: a battery pack, a voltage conversion circuit, a switch, and a three-leg conversion circuit;

The three bridge arm conversion circuit includes: a first bridge arm, a second bridge arm, a third bridge arm, a first inductor, a second inductor, a DC bus capacitor, and a first capacitor; the first bridge arm includes a first bridge arm connected in series. A switching tube and a second switching tube; the second bridge arm includes a third switching tube and a fourth switching tube connected in series; the third bridge arm includes a fifth switching tube and a sixth switching tube connected in series; the first A bridge arm, the second bridge arm, the third bridge arm and the DC bus capacitor are connected in parallel between the positive output end of the bus and the negative output end of the bus; the midpoint of the first bridge is connected to the The first end of the first inductor is connected, and the second end of the first inductor is connected as the positive voltage input end of the three-leg topology device; the midpoint of the second bridge leg is used as the three-leg topology device The negative voltage input end of the third bridge arm is connected to the first end of the second inductor, and the second end of the second inductor is the output end of the three bridge arm topology device, respectively Connected to the load and the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the negative voltage input terminal;

The battery pack is connected to the first terminal of the voltage conversion circuit, and the anode of the second terminal of the voltage conversion circuit is respectively connected to the positive output terminal of the bus bar and the positive voltage input terminal through the switch. The negative pole of the second terminal of the voltage conversion circuit is connected to the negative output terminal of the bus, the live wire of the mains AC power supply is connected to the positive voltage input via the switch, and the neutral wire of the mains AC power supply is connected to the negative The voltage input terminal is connected; the switch is used for controlling the voltage conversion circuit to charge the battery pack in the mains power supply mode; in the battery power supply mode, controlling the voltage conversion circuit to discharge the battery pack .

In a first possible implementation manner, the switch includes: a first switch, a second switch, and a balance element; the positive pole of the second terminal of the voltage conversion circuit is connected to the fixed terminal of the first switch, and the first switch The first selection terminal of a switch is connected to the first terminal of the balance component, the second terminal of the balance component is connected to the positive output terminal of the bus, and the second selection terminal of the first switch is connected to the The positive voltage input terminal is connected, the first terminal of the second switch is connected to the live wire of the mains AC power source, the second terminal of the second switch is connected to the positive voltage input terminal, and the voltage conversion circuit The negative pole of the second end is connected to the negative output end of the bus; the balance component is used to balance the voltage between the bus and the voltage conversion circuit; in the mains power supply mode, the first switch is fixed Terminal is connected with the first selection terminal of the first switch, and the second switch is closed; in the battery power supply mode, the fixed terminal of the first switch is connected with the second selection terminal of the first switch, The second switch is off.

Optionally, the first switch is any one of the following: a double-throw relay, a bidirectional electronic switch, and a thyristor. Optionally, the second switch is any one of the following: a single-throw relay, a one-way electronic switch, and a thyristor. Optionally, the balance component is any one of the following: a varistor, a thermistor with a negative temperature coefficient, and a third inductor.

Optionally, the balance element is a resistor, and the switch further includes: a third switch; the anode of the second terminal of the voltage conversion circuit is connected to the first terminal of the third switch, and the third switch The second end of the bus is connected to the positive output end of the bus; or the third switch is connected in parallel with the resistor; the voltage between the bus and the voltage conversion circuit in the mains power supply mode When the difference is less than or equal to the preset threshold, the third switch is closed; in the battery power supply mode, the third switch is opened. Optionally, the third switch is any one of the following: a single-throw relay, a one-way electronic switch, and a thyristor.

In a second possible implementation manner, the switch includes: a first switch, a second switch, and a balancing element; the positive pole of the second terminal of the voltage conversion circuit is respectively the first terminal of the first switch, and, The first selection end of the second switch is connected, the second end of the first switch is connected to the first end of the balance component, and the second end of the balance component is connected to the positive output end of the bus , The second selection terminal of the second switch is connected to the live wire of the AC power source, the fixed terminal of the second switch is connected to the positive voltage input terminal, and the negative electrode of the second terminal of the voltage conversion circuit is connected to The negative output end of the bus is connected; the balance component is used to balance the voltage between the bus and the voltage conversion circuit; in the mains power supply mode, the first switch is closed, and the second switch The fixed terminal of the second switch is connected with the second selection terminal of the second switch; in the battery power supply mode, the first switch is turned off, and the fixed terminal of the second switch is connected to the first selection terminal of the second switch.端连接。 Connected.

Optionally, the first switch is any one of the following: a single-throw relay, a one-way electronic switch, and a thyristor. Optionally, the second switch is any one of the following: a double-throw relay, a bidirectional electronic switch, and a thyristor. Optionally, the balance component is any one of the following: a varistor, a thermistor with a negative temperature coefficient, and a third inductor.

In a third possible implementation manner, the switch includes: a first switch, a second switch, a third switch, and a balance element; the positive pole of the second terminal of the voltage conversion circuit is connected to the first switch of the first switch. The terminal is connected to the first terminal of the third switch, the second terminal of the first switch is connected to the positive voltage input terminal, and the first terminal of the second switch is connected to the live wire of the AC power supply , The second terminal of the second switch is connected to the positive voltage input terminal, the second terminal of the third switch is connected to the first terminal of the balance component, and the second terminal of the balance component is connected to The positive output end of the bus is connected, the negative pole of the second end of the voltage conversion circuit is connected to the negative output end of the bus; the balancing component is used to balance the voltage between the bus and the voltage conversion circuit; In the mains power supply mode, the first switch is opened, the second switch and the third switch are closed; in the battery power supply mode, the first switch is closed, and the second switch and the third switch are closed. The third switch is off.

Optionally, the first switch is any one of the following: a single-throw relay, a one-way electronic switch, and a thyristor. Optionally, the second switch is any one of the following: a single-throw relay, a one-way electronic switch, and a thyristor. Optionally, the third switch is any one of the following: a single-throw relay, a one-way electronic switch, and a thyristor. Optionally, the balance component is any one of the following: a varistor, a thermistor with a negative temperature coefficient, and a third inductor.

Optionally, the balance element is a resistor, and the switch further includes: a fourth switch; the anode of the second terminal of the voltage conversion circuit is connected to the first terminal of the fourth switch, and the fourth switch The second end of the bus is connected to the positive output end of the bus; or, the fourth switch is connected in parallel with the resistor; the voltage between the bus and the voltage conversion circuit in the mains power supply mode When the difference is less than or equal to the preset threshold, the fourth switch is closed; in the battery power supply mode, the fourth switch is opened. Optionally, the fourth switch is any one of the following: a single-throw relay, a one-way electronic switch, and a thyristor.

In a fourth possible implementation manner, the voltage conversion circuit includes: a fourth bridge arm, a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, a transformer, a third inductor, a second capacitor, and a third capacitor;

The fourth bridge arm includes a seventh switch tube and an eighth switch tube, and the first end of the seventh switch tube is connected to the first end of the eighth switch tube;

The fifth bridge arm includes a ninth switch tube and a tenth switch tube, and the first end of the ninth switch tube is connected to the first end of the tenth switch tube;

The sixth bridge arm includes an eleventh switch tube and a twelfth switch tube, and the first end of the eleventh switch tube is connected to the first end of the twelfth switch tube;

The seventh bridge arm includes a thirteenth switch tube and a fourteenth switch tube, and the first end of the thirteenth switch tube is connected to the first end of the fourteenth switch tube;

The fourth bridge arm is connected in parallel with the fifth bridge arm, the sixth bridge arm and the seventh bridge arm are connected in parallel with the third capacitor, and the first end of the transformer is connected to the fourth bridge arm in parallel. The midpoint of the bridge arm is connected, the second end of the transformer is connected to the midpoint of the fifth bridge arm, and the third end of the transformer is connected to the fifth bridge through the third inductor and the second capacitor. The midpoint of the bridge arm is connected, and the fourth end of the transformer is connected with the midpoint of the sixth bridge arm;

The second terminal of the seventh switch tube is the anode of the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch tube is the cathode of the first terminal of the voltage conversion circuit. The second terminal of the three-switch tube is the positive pole of the second terminal of the voltage conversion circuit, and the second terminal of the fourteenth switch tube is the negative pole of the second terminal of the voltage conversion circuit.

In the second aspect, the present application also provides an uninterruptible power supply system, the system includes: a commercial AC power supply, a load, and the three-arm topology device according to any one of the first aspect; wherein, the The live wire of the mains AC power supply is connected to the positive voltage input end of the three-arm topology device, the neutral wire of the mains AC power supply is connected to the negative voltage input end of the three-arm topology device, and the three bridge arm The output terminal of the topology device is connected to the load.

In the third aspect, the present application also provides a method for controlling the three-arm topology device, the method is used to control the three-arm topology device provided in the first possible implementation manner of the first aspect, and the method includes: In the mains power supply mode, the fixed terminal of the first switch is controlled to communicate with the first selection terminal of the first switch, and the second switch is closed; in the battery power supply mode, the fixed terminal of the first switch is controlled to be connected to the first switch. The second selection terminal of a switch is connected, and the second switch is disconnected.

Optionally, the method further includes: in the mains power supply mode, when the voltage difference between the bus and the voltage conversion circuit of the three-leg topology device is less than or equal to a preset threshold, controlling the third switch to close ; In the battery power supply mode, the third switch is controlled to be turned off.

In a fourth aspect, this application also provides a method for controlling a three-arm topology device, which is used to control the three-arm topology device provided in the second possible implementation manner of the first aspect, and the method includes: In the mains power supply mode, the first switch is controlled to be closed, and the fixed end of the second switch is connected to the second selection end of the second switch; in the battery power supply mode, the first switch is controlled to open, and the second The fixed end of the switch is in communication with the first selection end of the second switch.

In a fifth aspect, the present application also provides a method for controlling a three-arm topology device. The method is used to control the three-arm topology device provided by the third possible implementation of the first aspect. The method includes: In the mains power supply mode, the first switch is controlled to be opened, and the second switch and the third switch are closed; in the battery power supply mode, the first switch is controlled to be closed, and the second switch and the third switch are opened.

Optionally, the method further includes: in the mains power supply mode, when the voltage difference between the bus bar and the voltage conversion circuit of the three-leg topology device is less than or equal to a preset threshold, controlling the fourth switch to close ; In the battery power supply mode, the fourth switch is controlled to be turned off.

The three-leg topology device, control method, and uninterruptible power supply system provided by the present application realize the charging or discharging of the battery pack by multiplexing the voltage conversion circuit, and the battery pack can be charged without an additional charger. In addition, whether in the mains power supply mode or the battery power supply mode, the voltage conversion circuit and the three-leg change circuit all participate in the work, that is, all the devices of the three-bridge topology device participate in the work. When the three-leg topology device is applied to a battery low-voltage high-current UPS system, the device reuse rate of the system can be improved, device design redundancy can be avoided, and the cost of the battery low-voltage high-current UPS system can be reduced.

Description of the drawings

In order to more clearly describe the technical solutions in the present application or related technologies, the following will briefly introduce the drawings that need to be used in the embodiments or related technical descriptions. Obviously, the drawings in the following description are of the present application. For some embodiments, for those of ordinary skill in the art, other drawings may be obtained based on these drawings without creative labor.

Figure 1 is a schematic structural diagram of a battery low-voltage high-current UPS system provided by related technologies;

Fig. 2 is a schematic diagram 1 of the first three-arm topology device provided by this application;

Figure 3 is a second schematic diagram of the first three-arm topology device provided by this application;

FIG. 4 is a schematic diagram of the second three-arm topology device provided by this application;

Figure 5 is a schematic diagram of a third three-arm topology device provided by this application;

FIG. 6 is a schematic diagram of a fourth three-arm topology device provided by this application;

FIG. 7 is a schematic diagram of a fifth three-arm topology device provided by this application;

FIG. 8 is a schematic diagram of the current in the mains power supply mode of the fourth three-leg topology device provided by this application;

FIG. 9 is a schematic diagram of the current in the mains power supply mode of the fourth three-leg topology device provided by this application;

FIG. 10 is a schematic diagram of the current in the mains power supply mode of the fourth three-leg topology device provided by this application;

FIG. 11 is a schematic diagram of the current in the mains power supply mode of the fourth three-leg topology device provided by this application;

FIG. 12 is a schematic diagram of the current in the battery power supply mode of the fourth three-leg topology device provided by this application;

FIG. 13 is a schematic diagram of the current in the battery power supply mode of the fourth three-leg topology device provided by this application;

FIG. 14 is a schematic diagram of a sixth three-arm topology device provided by this application;

FIG. 15 is a schematic diagram of a seventh three-arm topology device provided by this application;

FIG. 16 is a schematic diagram of an eighth three-arm topology device provided by this application;

FIG. 17 is a schematic diagram of a ninth three-arm topology device provided by this application;

FIG. 18 is a schematic diagram of the tenth three-arm topology device provided by this application;

FIG. 19 is a schematic diagram of the eleventh three-arm topology device provided by this application;

20 is a schematic diagram of a twelfth three-arm topology device provided by this application;

FIG. 21 is a schematic diagram of the thirteenth three-arm topology device provided by this application;

FIG. 22 is a schematic diagram of the fourteenth three-arm topology device provided by this application;

FIG. 23 is a schematic diagram of the fifteenth three-arm topology device provided by this application.

Detailed ways

In order to make the purpose, technical solutions and advantages of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are Apply for some examples, but not all examples. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of this application.

Figure 1 is a structural diagram of a battery low-voltage high-current UPS system provided by related technologies. As shown in Figure 1, at present, common battery low-voltage and high-current UPS systems include: chargers, battery packs, unidirectional direct current (Direct Current-Direct Current, referred to as: DC-DC) converters, AC power supply (Alternating Current, referred to as: AC), Vienna rectifier converter, half-bridge inverter.

In the mains power supply mode (that is, when AC power is supplied), the Vienna rectifier converter converts the mains AC power into direct current, the half-bridge inverter converts the direct current into alternating current and supplies it to the load, and the charger charges the battery pack. In the mains power supply mode, the Vienna rectifier converter, half-bridge inverter and charger participate in the work. In this mode, the DC-DC converter is in an idle state.

In the battery-powered mode (that is, when the battery pack is powered), the DC-DC converter boosts the DC power output by the battery pack, and the half-bridge inverter converts the DC power to AC power and provides it to the load. That is, the DC-DC converter and the half-bridge inverter participate in the work. In battery-powered mode, the Vienna rectifier converter and charger are in an idle state.

That is to say, when the existing battery low-voltage and high-current UPS system is working, some components are in an idle state, which makes the device reuse rate of the existing battery low-voltage and high-current UPS system low, resulting in a relatively high cost of the battery low-voltage and high-current UPS system. high.

Considering the above problems, the embodiment of the present application provides a three-leg topology device. When the device is applied to a battery low-voltage and high-current UPS system, whether it is in the mains power supply mode or the battery power supply mode, all components of the device are Participation in the work has improved the device reuse rate of the battery low-voltage and high-current UPS system, thereby reducing the cost of the battery low-voltage and high-current UPS system.

The technical solution of the present application will be described in detail below in conjunction with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

FIG. 2 is a schematic diagram 1 of the first three-arm topology device provided by this application. As shown in FIG. 2, the three-arm topology device may include: a battery pack, a voltage conversion circuit, a switch, and a three-leg conversion circuit.

The three bridge arm conversion circuit may include: a first bridge arm, a second bridge arm, a third bridge arm, a first inductor L1, a second inductor L2, a DC bus capacitor E1, and a first capacitor Co.

The first bridge arm includes a first switching tube Q1 and a second switching tube Q2. The first switching tube Q1 and the second switching tube Q2 are connected in series between BUS+ and BUS-, and BUS+ is the positive output terminal of the bus. -That is, the negative output terminal of the bus. For example, the first terminal of the first switching tube Q1 is connected to BUS+, the second terminal of the first switching tube Q1 is connected to the first terminal of the second switching tube Q2, and the second terminal of the second switching tube Q2 is connected to BUS- connect. Among them, the common end of the first switching tube Q1 and the second switching tube Q2 is called the midpoint of the first bridge arm. In some embodiments, the first bridge arm may also be referred to as a power factor correction (Power Factor Correction, PFC for short) side high frequency bridge arm.

The second bridge arm includes a third switching tube Q3 and a fourth switching tube Q4, and the third switching tube Q3 and the fourth switching tube Q4 are connected in series between BUS+ and BUS-. For example, the first terminal of the third switching tube Q3 is connected to BUS+, the second terminal of the third switching tube Q3 is connected to the first terminal of the fourth switching tube Q4, and the second terminal of the fourth switching tube Q4 is connected to BUS- connect. Among them, the common end of the third switching tube Q3 and the fourth switching tube Q4 is called the midpoint of the second bridge arm. In some embodiments, the second bridge arm may also be referred to as a bridge arm shared by the PFC and an inverter (inverter, INV for short).

The third bridge arm includes a fifth switching tube Q5 and a sixth switching tube Q6, and the fifth switching tube Q5 and the sixth switching tube Q6 are connected in series between BUS+ and BUS-. For example, the first terminal of the fifth switching tube Q5 is connected to BUS+, the second terminal of the fifth switching tube Q5 is connected to the first terminal of the sixth switching tube Q6, and the second terminal of the sixth switching tube Q6 is connected to BUS- connect. Among them, the common end of the fifth switching tube Q5 and the sixth switching tube Q6 is called the midpoint of the third bridge arm. In some embodiments, the third bridge arm may also be referred to as an INV-side high-frequency bridge arm.

The DC bus capacitor E1 is connected between BUS+ and BUS-. That is, the first bridge arm, the second bridge arm, the third bridge arm and the DC bus capacitor E1 are connected in parallel between BUS+ and BUS-.

The first inductor L1 is a high-frequency inductor on the PFC side, and the second inductor L2 is a high-frequency inductor on the INV side. The midpoint of the first bridge arm is connected to the first end of the first inductor L1, and the second end of the first inductor L1 is used as the positive voltage input terminal AC_L of the three bridge arm topology device. The midpoint of the second bridge arm is used as the negative voltage input terminal AC_N of the three bridge arm topology device. The midpoint of the third leg is connected to the first end of the second inductor L2, and the second end of the second inductor L2 is the output end of the three-leg topology device, which is respectively connected to the load and the first end of the first capacitor Co, The second terminal of the first capacitor Co is connected to the negative voltage input terminal AC_N.

The positive pole of the battery pack is connected to the positive pole of the first end of the voltage conversion circuit, and the negative pole of the battery pack is connected to the negative pole of the first end of the voltage conversion circuit. The positive pole of the second end of the voltage conversion circuit is connected to BUS+ and the positive voltage input terminal AC_L through a switch, the negative pole of the second end of the voltage conversion circuit is connected to BUS-, and the live wire of the mains AC power supply AC is connected to the positive voltage input terminal AC_L through the switch. Connected, the neutral line of the mains AC power supply AC is connected to the negative voltage input terminal AC_N.

The aforementioned battery pack may include at least one battery, which may be specifically determined according to the power of the UPS system applied by the three-leg topology device. For example, the UPS system may be an online type with a power between 1 kW and 3 kW. The UPS system, in other words, the UPS can be a battery low-voltage high-current UPS system.

In this embodiment, there are two power supply modes in the three-leg topology device, namely: a mains power supply mode and a battery power supply mode. The mains power supply mode mentioned here can be a mode in which the mains AC power supply AC provides stable mains power; the battery power supply mode can be a mode in which the battery pack of the UPS system supplies power. At this time, the mains AC power supply AC input The electricity is low voltage, or there is no mains input. Through the switch, the three-leg topology device can switch between the above two modes.

In the mains power supply mode, the switch can control the mains AC power supply AC to supply power to the three-leg conversion circuit. At this time, the three-leg conversion circuit works in AC-AC mode. For example, the PFC of the three-leg conversion circuit converts the AC input from the mains AC power supply to DC (that is, rectifies the AC input from the mains AC power supply), and the DC bus capacitor E1 filters the DC power converted by the PFC (also It can be called a voltage stabilization) to obtain a stable direct current. The INV of the three-arm conversion circuit converts the stable direct current into alternating current and then outputs it to the load to supply power to the load.

It should be noted that although the above-mentioned PFC converts AC power into DC power, the DC power still contains a certain pulsating AC component, and this pulsating AC component is called ripple voltage. Therefore, in the mains power supply mode, the DC bus capacitor E1 can filter the DC power obtained by the PFC conversion (also referred to as voltage stabilization) to filter the ripple voltage in the DC power and obtain a smooth and stable DC voltage. At the same time, the DC bus capacitor E1 can store energy.

In the mains power supply mode, the switch can control the voltage conversion circuit to charge the battery pack. For example, the switch can control the voltage conversion circuit to charge the battery pack when the battery pack is in a mains power supply mode. That is, the charging of the battery pack is realized by the multiplexing voltage conversion circuit, and no additional charger is required. At this time, in the mains power supply mode, the voltage conversion circuit and the three-leg change circuit both participate in the work, that is, all the components of the three-leg topology device participate in the work.

Exemplarily, the switch can control the voltage conversion circuit to be connected between BUS+ and BUS-, the voltage conversion circuit works in the BUCK mode (i.e. step-down mode), and the BUS voltage output by the DC bus capacitor E1 (ie the DC bus capacitor E1) The voltage obtained by filtering the DC power obtained by the PFC conversion) is stepped down to obtain the charging voltage of the battery pack, and the charging voltage is used to charge the battery pack. At this time, the battery pack serves as the output source of the voltage conversion circuit.

1, when a charger is used to charge a battery pack in the related art, the charger needs to be provided with a rectifier circuit and a step-down circuit. The rectifier circuit is used to rectify the AC power provided by the commercial AC power supply to obtain DC power. The step-down circuit is used to step-down the DC power to obtain the charging voltage of the battery pack. Since the AC power provided by the mains AC power supply fluctuates in a wide voltage range, the step-down circuit set in the charger needs to achieve a wide range of voltage regulation, resulting in low voltage conversion efficiency of the step-down circuit. Therefore, when using charging When the charger is charging the battery pack, the charging efficiency of the charger is low.

In the embodiment of the present application, the BUS voltage output by the DC bus capacitor E1 is a stable DC voltage obtained by the PFC rectification of the three-leg conversion circuit. Therefore, the BUS voltage output by the DC bus capacitor E1 is used for charging the battery pack. , The voltage conversion circuit can be reused to reduce the BUS voltage output by the DC bus capacitor E1, and there is no need to separately set up a rectifier circuit. In other words, the PFC of the three-leg conversion circuit is multiplexed to obtain the direct current for charging the battery pack.

In addition, because the BUS voltage output by the DC bus capacitor E1 is a stable DC current, the BUS voltage output by the DC bus capacitor E1 can be stepped down without using a voltage conversion circuit with a wide range of voltage regulation, which improves the voltage conversion. The conversion efficiency of the circuit further improves the charging efficiency of the battery pack.

In the battery power supply mode, the switch can control the voltage conversion circuit to discharge the battery pack. Exemplarily, the switch can control the voltage conversion circuit to switch on between the high-frequency inductor (ie, the first inductor L1) and BUS- on the PFC side. At this time, the voltage conversion circuit is connected in series with "the first inductance L1 and the first leg of the three-leg conversion circuit constitute a Boost boost circuit" to achieve a two-stage boost process when discharging the battery pack. Specifically, the voltage conversion circuit works in Boost mode (ie, boost mode), and performs a one-stage boosting process on the output voltage of the battery pack. The first inductor L1 and the first leg of the three-leg conversion circuit form the Boost boost circuit. , The output voltage of the battery pack is subjected to a two-stage boosting process, and the boosted voltage is input to the DC bus capacitor E1 of the three bridge arm conversion circuit to maintain the bus voltage balance.

In a UPS system with low-voltage and high-current batteries, the output voltage of the battery pack is relatively low, while the voltage required by the load is relatively high. Therefore, when the three-leg topology device is applied to a battery low-voltage and high-current UPS system, when a battery pack is used to power the load in a battery low-voltage and high-current UPS system, the three-leg topology device needs to be a lower voltage Raise to a higher voltage, that is, need to perform a step-up process with a larger pressure difference. If the voltage conversion circuit is connected in parallel with "the first inductance L1 and the first leg of the three-leg conversion circuit constitute a Boost boost circuit", only the voltage conversion circuit is used to perform the boost operation (that is, the voltage conversion circuit is used to perform a boost). Stage boost processing), there will be the following problems:

1. The maximum boost ratio of the voltage conversion circuit (for example, the output voltage divided by the input voltage) is limited, which may cause the voltage boosted by the voltage conversion circuit to use the maximum boost ratio, which is still less than the load required by the UPS system with low battery and high current The voltage cannot meet the needs of the UPS system with low voltage and high current battery.

2. The higher the boost ratio, the lower the conversion efficiency of the voltage conversion circuit, and the greater the risk of current stress and heat loss of the voltage conversion circuit. Therefore, the above-mentioned use of the voltage conversion circuit for the first-level boosting process causes the voltage conversion circuit to perform a higher boosting ratio boosting process, resulting in lower conversion efficiency of the voltage conversion circuit, risk of current stress and heat loss of the voltage conversion circuit The risk is higher.

Considering the above-mentioned problems of using the voltage conversion circuit to perform one-stage boost processing, this application connects the voltage conversion circuit in series with "the first inductor L1 and the first leg of the three-leg conversion circuit constitute a boost boost circuit" The two-stage boosting method can make the Boost boost circuit composed of the first inductor L1 and the first leg of the three-leg conversion circuit share part of the voltage boosting operation, so as to obtain a larger boost ratio at the same time, In addition, the voltage conversion circuit itself does not need to perform a step-up process with a large voltage difference. When the voltage difference between the input voltage and the output voltage of the voltage conversion circuit is smaller, that is, the step-up ratio is smaller, the voltage conversion efficiency of the voltage conversion circuit is higher. Therefore, the conversion efficiency of the voltage conversion circuit can be improved through the above-mentioned two-stage boosting method, thereby reducing the risk of current stress and heat loss of the voltage conversion circuit, and improving the reliability of the UPS system with low battery and high current.

In the battery power supply mode, the battery pack is the input source of the voltage conversion circuit, and the output of the voltage conversion circuit is the power supply of the three-leg conversion circuit. At this time, the three-leg conversion circuit works in DC-AC mode. For example, the first leg of the three-leg conversion circuit and the first inductor L1 work in Boost mode, the DC bus capacitor E1 filters the boosted DC power to obtain stable DC power, and the third leg works in inverter mode. The stable direct current is converted into alternating current and then output to the load to supply power to the load. At the same time, the DC bus capacitor E1 can store energy. At this time, in the battery power supply mode, both the voltage conversion circuit and the three-leg change circuit participate in the work, that is, all the components of the three-leg topology device participate in the work.

It can be understood that the voltage conversion circuit involved in the embodiment of the present application may be any circuit with a bidirectional voltage conversion function. For example, a voltage conversion circuit with soft switching, a voltage conversion circuit with hard switching, and so on. The voltage conversion circuit may be a voltage conversion circuit with electrical isolation, or a voltage conversion circuit without electrical isolation. Exemplarily, the voltage conversion circuit may also be referred to as a DC-DC converter.

FIG. 3 is a second schematic diagram of the first three-leg topology device provided by this application. As shown in FIG. The bridge arm, the sixth bridge arm, the seventh bridge arm, the transformer TX11, the third inductor L3, the second capacitor C2, and the third capacitor E2.

The fourth bridge arm includes a seventh switching tube Q7 and an eighth switching tube Q8, and a first end of the seventh switching tube Q7 is connected to a first end of the eighth switching tube Q8. At this time, the common end of the seventh switching tube Q7 and the eighth switching tube Q8 is called the midpoint of the fourth bridge arm.

The fifth bridge arm includes a ninth switching tube Q9 and a tenth switching tube Q10, and a first end of the ninth switching tube Q9 is connected to a first end of the tenth switching tube Q10. At this time, the common end of the ninth switching tube Q9 and the tenth switching tube Q10 is called the midpoint of the fifth bridge arm.

The sixth bridge arm includes an eleventh switching tube Q11 and a twelfth switching tube Q12, and a first end of the eleventh switching tube Q11 is connected to a first end of the twelfth switching tube Q12. At this time, the common end of the eleventh switch transistor Q11 and the twelfth switch transistor Q12 is called the midpoint of the sixth bridge arm.

The seventh bridge arm includes a thirteenth switching tube Q13 and a fourteenth switching tube Q14, and the first end of the thirteenth switching tube Q13 is connected to the first end of the fourteenth switching tube Q14. At this time, the common end of the thirteenth switching tube Q13 and the fourteenth switching tube Q14 is called the midpoint of the seventh bridge arm.

The fourth bridge arm is connected in parallel with the fifth bridge arm. For example, the second terminal of the seventh switching tube Q7 is connected to the second terminal of the ninth switching tube Q9, and the second terminal of the eighth switching tube Q8 is connected to the second terminal of the tenth switching tube Q10. connect.

The sixth bridge arm, the seventh bridge arm, and the third capacitor E2 are connected in parallel. For example, the second end of the eleventh switch transistor Q11 is connected to the second end of the thirteenth switch transistor Q13 and the first end of the third capacitor E2, and the second end of the twelfth switch transistor Q12 The two ends are connected to the second end of the fourteenth switch tube Q14 and the second end of the third capacitor E2. It should be understood that the third capacitor E2 may be a DC capacitor for providing a filtering function, so that the voltage conversion circuit provides stable DC power when charging or discharging the battery pack.

The first end A of the transformer TX11 is connected to the midpoint of the fourth bridge arm, the second end B of the transformer TX11 is connected to the midpoint of the fifth bridge arm, and the third end of the transformer TX11 is connected to the midpoint of the fifth bridge arm. C is connected to the midpoint of the fifth bridge arm through the third inductor L3 and the second capacitor C2, and the fourth terminal D of the transformer TX11 is connected to the midpoint of the sixth bridge arm.

In this voltage conversion circuit, the second terminal of the seventh switch tube Q7 is the positive pole of the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch tube Q8 is the second terminal of the voltage conversion circuit. One end of the negative pole, the second end of the thirteenth switch tube Q13 is the positive pole of the second end of the voltage conversion circuit, and the second end of the fourteenth switch tube Q14 is the second end of the voltage conversion circuit. The negative terminal of the terminal.

When the voltage conversion circuit shown in Figure 3 is used to charge the battery pack, Q11, Q12, Q13, and Q14 are used as switch tubes, and the external diodes (also called parasitic diodes, etc.) of Q7, Q8, Q9, and Q10 are used as rectifiers. Among them, Q11 and Q14 are turned on at the same time, and Q12 and Q13 are turned on at the same time. For example, a fixed frequency and constant duty cycle control method can be used to charge the battery pack. The constant duty cycle mentioned here refers to the use of the same duty cycle for control so that the on-time of Q11 and Q14 are the same as the on-time of Q12 and Q13. The fixed frequency mentioned here refers to the use of fixed frequency for voltage regulation control.

When the voltage conversion circuit shown in Figure 3 is used to discharge the battery pack, Q7, Q8, Q9, and Q10 are used as switch tubes, and the external diodes (also called parasitic diodes, etc.) of Q11, Q12, Q13, and Q14 are used as rectifiers. Among them, Q7 and Q10 are turned on at the same time, and Q8 and Q9 are turned on at the same time. For example, a variable frequency and constant duty cycle control method can be used to discharge the battery pack. The constant duty cycle mentioned here refers to the use of the same duty cycle to control Q7, Q8, Q9, and Q10, so that the conduction duration of Q7 and Q10 is the same as the conduction duration of Q8 and Q9. The frequency conversion mentioned here refers to the use of frequency conversion for voltage regulation and control.

Through the above-mentioned structure of the voltage conversion circuit, the soft switching of the voltage conversion circuit can be realized. Soft-Switching is a kind of switching technology relative to Hard-Switching. The soft switching technology can make the switch tube in the voltage conversion circuit lower the voltage to zero before turning on, and before the switch tube is turned off, the current is first reduced to zero (ie, zero voltage turn on, zero current turn off) to eliminate The overlap of voltage and current in the switching process of the switching tube reduces their rate of change, thereby greatly reducing or even eliminating the switching loss of the voltage conversion circuit, and realizing the high frequency of the voltage conversion circuit.

Because of the poor voltage regulation capability of the voltage conversion circuit with soft switching. That is to say, when the voltage conversion circuit achieves a large voltage difference, the voltage conversion circuit can only achieve zero voltage turn-on, and cannot achieve zero current turn-off, resulting in the voltage conversion circuit unable to achieve zero voltage turn-on and zero current turn-off. Soft switching under full working conditions, that is, the voltage conversion circuit cannot work under the full working conditions of zero voltage turn-on and zero current shut-off, which in turn causes the conversion efficiency of the voltage conversion circuit to be lower than the conversion efficiency under full working conditions, increasing the voltage The risk of current stress and heat loss of the conversion circuit.

Therefore, when the above-mentioned voltage conversion circuit with soft switching is applied to the three-leg topology device provided in the embodiment of the present application, the voltage conversion circuit is combined with the "first inductance L1 and the first bridge of the three-leg conversion circuit". The arms constitute the Boost boost circuit, which is connected in series, which enables the voltage conversion circuit to achieve a soft switching function with a fixed boost ratio (for example, the fixed boost ratio can achieve a smaller voltage difference). The first inductor L1 and the third inductor The Boost boost circuit composed of the first leg of the bridge arm conversion circuit realizes the voltage regulation function, that is, while obtaining a larger boost ratio, the voltage conversion circuit with soft switching does not need to perform a larger voltage difference. Boost processing. In this way, the voltage conversion circuit with soft switching can work under the full working conditions of zero voltage turn-on and zero current turn-off, which improves the conversion efficiency of the voltage conversion circuit with soft switching, thereby reducing the cost of the voltage conversion circuit with soft switching. Current stress risk and heat loss risk improve the reliability of UPS systems with low battery voltage and high current.

It should be understood that FIG. 3 is only a schematic diagram of a voltage conversion circuit with soft switching. In a specific implementation, the solution of the embodiment of the present application may also adopt other voltage conversion circuits with soft switching, which will not be repeated.

In addition, although the above-mentioned FIG. 3 is a schematic diagram of an example of a voltage conversion circuit provided with electrical isolation (for example, the transformer in FIG. 3 realizes the electrical isolation of the voltage conversion circuit), it should be understood that the voltage conversion circuit involved in the embodiment of the present application It can be a voltage conversion circuit with electrical isolation, or a voltage conversion circuit without electrical isolation. For example, the voltage conversion circuit has electrical isolation, the first leg of the three-leg conversion circuit is not electrically isolated, or the voltage conversion circuit is not electrically isolated, and the first leg of the three-leg conversion circuit is electrically isolated, or the voltage conversion The circuit has electrical isolation, the first bridge arm of the three-leg conversion circuit has electrical isolation, or the voltage conversion circuit has no electrical isolation, and the first bridge arm of the three-leg conversion circuit has no electrical isolation.

It should be noted that when the above-mentioned three-leg topology device switches from the mains power supply mode to the battery power supply mode, or when switching from the battery power supply mode to the mains power supply mode, there is a certain time difference due to the mode switching (for example, from There may be a time difference of X seconds from the time the mains is disconnected to the battery pack. Therefore, within this time difference, the three-leg topology device can use the voltage stored in the DC bus capacitor E1 to supply power to the load to provide stable AC power to the load. Avoid load power down.

The three-leg topology device provided by the embodiment of the present application realizes the charging or discharging of the battery pack by multiplexing the voltage conversion circuit, that is, the voltage conversion circuit, and can realize the charging function of the battery pack without adding an additional charger. In addition, whether in the mains power supply mode or the battery power supply mode, the voltage conversion circuit and the three-leg change circuit all participate in the work, that is, all the devices of the three-bridge topology device participate in the work. When the three-leg topology device is applied to a battery low-voltage high-current UPS system, the device reuse rate of the system can be improved, device design redundancy can be avoided, and the cost of the battery low-voltage high-current UPS system can be reduced.

The following is an example of the implementation of the above switch:

Continuing to refer to FIG. 2, in the three-leg topology device, the switch may include, for example, a first switch K1, a second switch K2, and balance components.

Wherein, the positive pole of the second terminal of the voltage conversion circuit is connected to the fixed terminal of the first switch K1, the first selection terminal of the first switch K1 is connected to the first terminal of the balance component, and the second terminal of the balance component is connected to BUS+, The second selection terminal of the first switch K1 is connected to the positive voltage input terminal AC_L, the first terminal of the second switch K2 is connected to the live wire of the mains AC power supply AC, and the second terminal of the second switch K2 is connected to the positive voltage input terminal AC_L , The negative pole of the second end of the voltage conversion circuit is connected to BUS-.

In the mains power supply mode, the fixed end of the first switch K1 is connected to the first selection end of the first switch K1, and the second switch K2 is closed; in the battery power supply mode, the fixed end of the first switch K1 is connected to the first switch K1 The second selection terminal of is connected, and the second switch K2 is disconnected. For example, the first switch K1 may be any selective switch that can be turned on or off according to a control signal, such as a double-throw relay, a bidirectional electronic switch, or a thyristor. The second switch K2 can be any switch that can be turned on or off according to a control signal, for example, a single-throw relay, a one-way electronic switch, a thyristor, and the like.

The above-mentioned balancing components are used to balance the voltage between the BUS of the three-leg conversion circuit and the voltage conversion circuit in the mains power supply mode, thereby avoiding the fixed end of the first switch K1 and the first selection end of the first switch K1 At the moment of connection, a relatively large current is input to the voltage conversion circuit, so that the voltage conversion circuit can be protected against overcurrent.

Continuing to refer to FIG. 2, in the first possible implementation manner, the above-mentioned balancing component may be, for example, a varistor RZ.

Fig. 4 is a schematic diagram of the second three-arm topology device provided by this application. As shown in FIG. 4, in the second possible implementation manner, the above-mentioned balance component may be, for example, a thermistor RT with a negative temperature coefficient.

Fig. 5 is a schematic diagram of a third three-arm topology device provided by this application. As shown in FIG. 5, in a third possible implementation manner, the above-mentioned balancing component may be, for example, a third inductor L3.

Fig. 6 is a schematic diagram of a fourth three-arm topology device provided by this application. As shown in FIG. 6, in a fourth possible implementation manner, the above-mentioned balancing component may be, for example, a resistor R1. In this implementation manner, the above-mentioned switch may further include: a third switch K3.

Continuing to refer to FIG. 6, the anode of the second terminal of the voltage conversion circuit is connected to the first terminal of the third switch K3, and the second terminal of the third switch K3 is connected to BUS+. FIG. 7 is a schematic diagram of a fifth three-arm topology device provided by this application. As shown in Fig. 7, in the fifth possible connection manner, the third switch K3 is connected in parallel with the resistor R1.

Referring to the switch shown in FIG. 6 or FIG. 7, in the mains power supply mode and when the voltage difference between the bus bar and the voltage conversion circuit is less than or equal to the preset threshold, the third switch K3 is closed to enable the voltage conversion circuit Charge the battery pack. In the battery power supply mode, the third switch K3 is turned off.

Exemplarily, the aforementioned third switch K3 may be any switch that can be turned on or off according to a control signal, for example, a single-throw relay, a one-way electronic switch, a thyristor, and the like.

It should be understood that the second switch K2 and the third switch K3 can be the same switch or different switches. For example, the second switch K2 uses a thyristor, and the third switch K3 uses a unidirectional electronic switch.

Taking the structure of the three-leg topology device shown in Figure 6 as an example, the state of each switch, the state of each switch tube, and the current trend of the three-leg topology device in different power supply modes are schematically described below:

Mains power supply mode: control the fixed end of the first switch K1 to connect with the first selection end of the first switch K1, the second switch K2 is closed, and the voltage conversion circuit between the BUS+ of the three-leg topology device and the voltage conversion circuit of the three-leg topology device When the voltage difference between the two is less than or equal to the preset threshold, the third switch K3 is controlled to close. At this time, the voltage conversion circuit works in Buck mode.

FIG. 8 is a schematic diagram of the current in the mains power supply mode of the fourth three-leg topology device provided by this application. As shown in Figure 8, in the first phase of the positive half cycle of the alternating current, the second switching tube Q2 and the fourth switching tube Q4 of the three-leg conversion circuit are controlled to be turned on, and the first switching tube Q1 and the third switching tube Q3 are turned off. Off. At this time, the current flow in the three-leg topology device is as follows:

1. The live wire of the mains AC power supply AC→the first inductor L1→the second switching tube Q2→the fourth switching tube Q4→the neutral wire of the mains AC power supply AC, forming an energy storage circuit of the inductance L1.

2. BUS+→the positive pole of the voltage conversion circuit→the positive pole of the battery pack→the negative pole of the battery pack→the negative pole of the voltage conversion circuit→BUS-, which constitutes the energy storage circuit of the battery pack.

Figure 9 is a schematic diagram of the current of the fourth three-leg topology device provided by this application in the mains power supply mode. As shown in Figure 9, in the second phase of the positive half cycle of the alternating current, the first switching transistor Q1 and the The fourth switching tube Q4 is turned on, and the second switching tube Q2 and the third switching tube Q3 are turned off. At this time, the current flow in the three-leg topology device is as follows:

1. The live wire of the mains AC power supply AC→the first inductor L1→the first switching tube Q1→the DC bus capacitor E1→the fourth switching tube Q4→the neutral line of the mains AC power supply AC, forming the inductor L1 and the mains at the same time Energy storage circuit for energy storage of DC bus capacitor E1.

FIG. 10 is a schematic diagram of the current of the fourth three-leg topology device provided by this application in the mains power supply mode. As shown in FIG. The third switching tube Q3 is turned on, and the second switching tube Q2 and the fourth switching tube Q4 are turned off. At this time, the current flow in the three-leg topology device is as follows:

1. The neutral line of the mains AC power supply AC → the third switching tube Q3 → the first switching tube Q1 → the first inductor L1 → the live wire of the mains AC power supply AC, forming an energy storage loop of the inductor L1.

FIG. 11 is a schematic diagram of the current in the mains power supply mode of the fourth three-leg topology device provided by this application. As shown in FIG. 11, in the second phase of the negative half cycle of the alternating current, the second switching transistor Q2 and the The third switching tube Q3 is turned on, and the first switching tube Q1 and the fourth switching tube Q4 are turned off. At this time, the current flow in the three-leg topology device is as follows:

1. The neutral wire of the mains AC power supply AC → the third switching tube Q3 → the DC bus capacitor E1 → the second switching tube Q2 → the first inductance L1 → the live wire of the mains AC power supply AC, forming the inductor L1 and the mains at the same time Energy storage circuit for energy storage of DC bus capacitor E1.

Battery power supply mode: control the fixed end of the first switch K1 to communicate with the second selection end of the first switch K1, and the second switch K2 and the third switch K3 are disconnected. At this time, the voltage conversion circuit works in Boost mode.

FIG. 12 is a schematic diagram of the current in the battery power supply mode of the fourth three-leg topology device provided by this application. As shown in FIG. The switching tube Q1, the third switching tube Q3, and the fourth switching tube Q4 are turned off. At this time, the current flow in the three-leg topology device is as follows:

The positive pole of the battery pack → the positive pole of the voltage conversion circuit → the first inductor L1 → the second switch tube Q2 → the negative pole of the voltage conversion circuit → the negative pole of the battery pack, forming an energy storage loop of the first inductor L1.

FIG. 13 is a schematic diagram of the current in the battery power supply mode of another three-leg topology device provided by this application. As shown in FIG. 13, in the second stage of the battery power supply mode, the first switch Q1 is controlled to be turned on, and the second The switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 are turned off. At this time, the current flow in the three-leg topology device is as follows:

The positive pole of the battery pack → the positive pole of the voltage conversion circuit → the first inductor L1 → the first switch tube Q1 → the DC bus capacitor E1 → the negative pole of the voltage conversion circuit → the negative pole of the battery pack, forming an energy storage circuit of the DC bus capacitor E1.

It should be understood that although the current trends of the three-leg topology devices shown in FIG. 8 to FIG. 12 are all schematically illustrated by taking the fourth three-leg topology device shown in FIG. 6 as an example. However, those skilled in the art can understand that the current trend and the states of each switch and each switch tube are also applicable to the three-leg topology device shown in FIG.

In addition, when the three-leg topology device of any structure of Figures 2 to 5 is used, the state of each switch, the state of each switch tube, and the current trend of the three-leg topology device in different modes are as follows:

Mains power supply mode: control the fixed end of the first switch K1 to communicate with the first selection end of the first switch K1, and the second switch K2 is closed. At this time, the voltage conversion circuit works in Buck mode.

In this mode, the state of each switch tube of the three-leg topology device in the mains power supply mode is the same as the state of each switch tube of the three-leg topology device in the mains power supply mode shown in FIG. 6. The current trend of the three-leg topology device is the same as the current trend of the three-leg topology device in the mains power supply mode shown in FIG.

Battery power supply mode: control the fixed terminal of the first switch K1 to be connected with the second selection terminal of the first switch K1, and the second switch K2 is turned off. At this time, the voltage conversion circuit works in Boost mode.

In this mode, the state of each switch tube of the three-leg topology device in the battery power supply mode is the same as the state of each switch tube of the three-leg topology device shown in FIG. 6 in the battery power supply mode. The current trend of the three-leg topology device is the same as the current trend of the three-leg topology device shown in FIG. 6 in the battery power supply mode. For details, please refer to the corresponding descriptions of FIG. 12 to FIG.

FIG. 14 is a schematic diagram of a sixth three-arm topology device provided by this application. As shown in FIG. 4, in the three-leg topology device, the switch may include, for example, a first switch K1, a second switch K2, and balance components.

The positive pole of the second terminal of the voltage conversion circuit is respectively connected to the first terminal of the first switch K1 and the first selection terminal of the second switch K2, and the second terminal of the first switch K1 is connected to the first terminal of the balance component, The second end of the balance component is connected to BUS+, the second selection end of the second switch K2 is connected to the live wire of the AC power supply, the fixed end of the second switch K2 is connected to the positive voltage input terminal AC_L, and the second terminal of the voltage conversion circuit The negative pole of the terminal is connected to BUS-.

In the mains power supply mode, the first switch K1 is closed, and the fixed end of the second switch K2 is connected to the second selection end of the second switch K2; in the battery power supply mode, the first switch K1 is open, and the second switch K2 The fixed end is connected to the first selection end of the second switch K2. For example, the first switch K1 may be any switch that can be turned on or off according to a control signal, for example, a single-throw relay, a one-way electronic switch, a thyristor, etc. The second switch K2 can be any selection switch that can be turned on or off according to a control signal, such as a double-throw relay, a bidirectional electronic switch, or a thyristor.

The above-mentioned balancing components are used to balance the voltage between the BUS+ of the three-leg conversion circuit and the voltage conversion circuit in the mains power supply mode, thereby avoiding the fixed end of the first switch K1 and the first selection end of the first switch K1 At the moment of connection, a relatively large current is input to the voltage conversion circuit, so that overcurrent protection can be realized for the voltage conversion circuit.

Continuing to refer to FIG. 14, in the sixth possible implementation manner, the above-mentioned balancing component may be, for example, a varistor RZ.

FIG. 15 is a schematic diagram of a seventh three-arm topology device provided by this application. As shown in FIG. 15, in a seventh possible implementation manner, the above-mentioned balance component may be, for example, a thermistor RT with a negative temperature coefficient.

FIG. 16 is a schematic diagram of an eighth three-arm topology device provided by this application. As shown in FIG. 16, in an eighth possible implementation manner, the above-mentioned balancing component may be, for example, a third inductor L3.

When the three-leg topology device of any structure of Figure 14 to Figure 16 is used, the state of each switch, the state of each switch tube, and the current trend of the three-leg topology device in different modes are as follows:

Mains power supply mode: control the first switch K1 to close, and the fixed end of the second switch K2 is connected to the second selection end of the second switch K2. At this time, the voltage conversion circuit works in Buck mode.

Battery power supply mode: the first switch K1 is controlled to be turned off, and the fixed end of the second switch K2 is connected to the first selection end of the second switch K2. At this time, the voltage conversion circuit works in Boost mode.

FIG. 17 is a schematic diagram of a ninth three-arm topology device provided by this application. As shown in FIG. 17, in a ninth possible implementation manner, the above-mentioned balancing component may be, for example, a resistor R1. In this implementation manner, the above-mentioned switch may further include: a third switch K3.

Continuing to refer to FIG. 17, the anode of the second terminal of the voltage conversion circuit is connected to the first terminal of the third switch K3, and the second terminal of the third switch K3 is connected to BUS+. FIG. 18 is a schematic diagram of the tenth three-arm topology device provided by this application. As shown in FIG. 18, in the tenth possible connection manner, the third switch K3 is connected in parallel with the resistor R1.

Referring to the switch shown in FIG. 17 or FIG. 18, in the mains power supply mode and when the voltage difference between the bus and the voltage conversion circuit is less than or equal to the preset threshold, the third switch K3 is closed to make the voltage conversion circuit Charge the battery pack. In the battery power supply mode, the third switch K3 is turned off.

It should be understood that the first switch K1 and the third switch K3 may be the same switch or different switches. For example, the first switch K1 uses a thyristor, and the third switch K3 uses a unidirectional electronic switch.

When the three-leg topology device of any structure of Figure 17 to Figure 18 is used, the state of each switch, the state of each switch tube, and the current trend of the three-leg topology device in different modes are as follows:

Mains power supply mode: control the first switch K1 to close, the fixed end of the second switch K2 is connected to the second selection end of the second switch K2, and the voltage conversion circuit between the BUS of the three-leg topology device and the three-leg topology device When the voltage difference between the two is less than or equal to the preset threshold, the third switch K3 is controlled to close. At this time, the voltage conversion circuit works in Buck mode.

Battery power supply mode: control the first switch K1 and the third switch K3 to be turned off, and the fixed end of the second switch K2 is connected to the first selection end of the second switch K2. At this time, the voltage conversion circuit works in Boost mode.

FIG. 19 is a schematic diagram of the eleventh three-leg topology device provided by this application. As shown in FIG. 19, in the three-leg topology device, the switch may include, for example, a first switch K1, a second switch K2, a third switch K3, and balance components.

Wherein, the anode of the second terminal of the voltage conversion circuit is connected to the first terminal of the first switch K1 and the first terminal of the third switch K3, the second terminal of the first switch K1 is connected to the positive voltage input terminal AC_L, and the second switch The first end of K2 is connected to the live wire of the mains AC power supply AC, the second end of the second switch K2 is connected to the positive voltage input terminal AC_L, and the second end of the third switch K3 is connected to the first end of the balance component, which is balanced The second end of the component is connected to BUS+, and the negative pole of the second end of the voltage conversion circuit is connected to BUS-.

In the mains power supply mode, the first switch K1 is opened, and the second switch K2 and the third switch K3 are closed; in the battery power supply mode, the first switch K1 is closed, and the second switch K2 and the third switch K3 are opened.

The above-mentioned balancing components are used to balance the voltage between the BUS of the three-leg conversion circuit and the voltage conversion circuit in the mains power supply mode, so as to avoid the moment when the first switch K3 is closed, a large current is input to the voltage conversion circuit, Thereby, overcurrent protection can be realized for the voltage switching circuit.

Continuing to refer to FIG. 19, in the eleventh possible implementation manner, the above-mentioned balancing component may be, for example, a varistor RZ.

FIG. 20 is a schematic diagram of a twelfth three-arm topology device provided by this application. As shown in FIG. 20, in a twelfth possible implementation manner, the above-mentioned balance component may be, for example, a thermistor RT with a negative temperature coefficient.

FIG. 21 is a schematic diagram of the thirteenth three-arm topology device provided by this application. As shown in FIG. 21, in the thirteenth possible implementation manner, the above-mentioned balancing component may be, for example, the third inductor L3.

When the three-leg topology device of any structure of Figure 19 to Figure 21 is used, the state of each switch, the state of each switch tube, and the current trend of the three-leg topology device in different modes are as follows:

Mains power supply mode: control the first switch K1 to open, and the second switch K2 and the third switch K3 to close. At this time, the voltage conversion circuit works in Buck mode.

Battery power supply mode: control the first switch K1 to close, and the second switch K2 and the third switch K3 to open. At this time, the voltage conversion circuit works in Boost mode.

Fig. 22 is a schematic diagram of a fourteenth three-arm topology device provided by this application. As shown in FIG. 22, in the fourteenth possible implementation manner, the above-mentioned balancing component may be, for example, a resistor R1. In this implementation manner, the above-mentioned switch may further include: a fourth switch K4.

Continuing to refer to Fig. 22, the positive pole of the second terminal of the voltage conversion circuit is connected to the first terminal of the fourth switch K4, and the second terminal of the fourth switch is connected to BUS+. FIG. 23 is a schematic diagram of the fifteenth three-arm topology device provided by this application. As shown in Fig. 23, in the fifteenth possible connection mode, the fourth switch K4 is connected in parallel with the resistor R1.

Referring to the switch shown in FIG. 22 or FIG. 23, in the mains power supply mode and when the voltage difference between the bus and the voltage conversion circuit is less than or equal to the preset threshold, the fourth switch K4 is closed to make the voltage conversion circuit Charge the battery pack. In the battery power supply mode, the fourth switch K4 is turned off.

Exemplarily, the aforementioned fourth switch K4 may be any switch that can be turned on or off according to a control signal, for example, a single throw relay, a one-way electronic switch, a thyristor, and the like.

In this embodiment, the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 can be any switch that can be turned on or off according to a control signal, for example, a single-throw relay, a one-way electronic Switches, thyristors, etc. It should be understood that the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 may be the same switch or different switches. For example, the first switch K1 uses a thyristor, the second switch K2, the third switch K3, and the fourth switch K4 use single-throw relays, etc., which is not limited in this embodiment.

When the three-leg topology device of any structure of Figure 22 to Figure 23 is used, the state of each switch, the state of each switch tube, and the current trend of the three-leg topology device in different modes are as follows:

Mains power supply mode: control the first switch K1 to open, the second switch K2 and the third switch K3 to close, and the voltage difference between the BUS of the three-leg topology device and the voltage conversion circuit of the three-leg topology device is less than When it is equal to the preset threshold value, the fourth switch K4 is controlled to be closed. At this time, the voltage conversion circuit works in Buck mode.

Battery power supply mode: control the first switch K1 to close, the second switch K2, the third switch K3 and the fourth switch K4 to open. At this time, the voltage conversion circuit works in Boost mode.

It should be understood that the above-mentioned Figure 2, Figures 4 to 7, and the switch shown in Figures 14 to 23 are only an example. Due to the numerous implementations of the switch, the application to the three bridges will not be listed here. Switch for arm topology device. In specific implementation, the switch can be selected according to actual needs to realize the function of controlling the voltage conversion circuit to charge the battery pack in the mains power supply mode, and the function of controlling the voltage conversion circuit to discharge the battery pack in the battery power supply mode. Go into details.

In addition, although the above three-leg topology circuit is applied to a battery low-voltage high-current UPS system as an example, those skilled in the art will understand that the three-leg topology circuit can also be applied to other UPS systems (such as large-scale UPS). Power UPS system), or other systems (such as inverter systems) that use different power sources (mains or battery packs) to supply power under different conditions, etc., and this will not be repeated here.

Furthermore, in the examples of the three-leg topology devices shown in FIGS. 2, 4 to 7 and FIGS. 14 to 23, the voltage conversion circuit may be any circuit with a bidirectional voltage conversion function. For example, the voltage conversion circuit shown in FIG. 3 is not limited to this.

The present application also provides an uninterruptible power supply system, which includes: a commercial AC power supply AC, a load, and the three-leg topology device shown in the foregoing embodiment (for example, FIG. 2, FIG. 4 to FIG. 7, and, The three-arm topology device shown in any one of Figures 14 to 23). Among them, the live wire of the mains AC power supply is connected to the positive voltage input terminal AC_L of the three-leg topology device, the neutral line of the mains AC power supply is connected to the negative voltage input terminal AC_N of the three-leg topology device, and the output of the three-leg topology device The terminal is connected to the load.

The uninterruptible power supply system provided in this application may be, for example, a battery low-voltage high-current UPS system, or an online medium and small power UPS system.

The implementation principle and technical effect of the UPS system provided in this application are similar to the foregoing three-arm topology device, and will not be repeated here.

It can be understood that the various numbers involved in this application (for example, the first switch tube, the second switch tube, the first switch, the second switch, etc.) are only for the convenience of the description, and are not used to limit the scope of the application. Scope of the embodiment.

Claims

A three-leg topology device, including: a battery pack, a voltage conversion circuit, a switch and a three-leg conversion circuit;

The three bridge arm conversion circuit includes: a first bridge arm, a second bridge arm, a third bridge arm, a first inductor, a second inductor, a DC bus capacitor, and a first capacitor;

The first bridge arm includes a first switch tube and a second switch tube connected in series;

The second bridge arm includes a third switch tube and a fourth switch tube connected in series;

The third bridge arm includes a fifth switch tube and a sixth switch tube connected in series;

The first bridge arm, the second bridge arm, the third bridge arm, and the DC bus capacitor are connected in parallel between the positive output end of the bus and the negative output end of the bus; the midpoint of the first bridge arm Connected to the first end of the first inductor, the second end of the first inductor is used as the positive voltage input end of the three-leg topology device; the midpoint of the second leg is used as the three-leg The negative voltage input end of the topology device; the midpoint of the third bridge arm is connected to the first end of the second inductor, and the second end of the second inductor is the output end of the three bridge arm topology device, Respectively connected to the load and the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the negative voltage input terminal;

The anode of the battery pack is connected to the anode of the first end of the voltage conversion circuit, the cathode of the battery pack is connected to the cathode of the first end of the voltage conversion circuit, and the anode of the second end of the voltage conversion circuit is connected. The switch is connected to the positive output terminal of the bus and the positive voltage input terminal respectively, the negative pole of the second terminal of the voltage conversion circuit is connected to the negative output terminal of the bus, and the live wire of the mains AC power supply passes through the The switch is connected to the positive voltage input terminal, and the neutral line of the mains AC power supply is connected to the negative voltage input terminal;

The switch is used to control the voltage conversion circuit to charge the battery pack in the mains power supply mode; and to control the voltage conversion circuit to discharge the battery pack in the battery power supply mode.
The device according to claim 1, wherein the switch comprises: a first switch, a second switch and balance components;

The positive pole of the second terminal of the voltage conversion circuit is connected to the fixed terminal of the first switch, the first selection terminal of the first switch is connected to the first terminal of the balance component, and the first terminal of the balance component is connected. The two ends are connected to the positive output end of the bus, the second selection end of the first switch is connected to the positive voltage input end, and the first end of the second switch is connected to the live wire of the mains AC power supply, The second terminal of the second switch is connected to the positive voltage input terminal, and the negative electrode of the second terminal of the voltage conversion circuit is connected to the negative output terminal of the bus;

The balance component is used to balance the voltage between the bus and the voltage conversion circuit;

In the mains power supply mode, the fixed terminal of the first switch is connected to the first selection terminal of the first switch, and the second switch is closed; in the battery power supply mode, the first switch The fixed end of is connected with the second selection end of the first switch, and the second switch is turned off.
3. The device according to claim 2, wherein the balance element is a resistor, and the switch further comprises: a third switch;

The positive pole of the second terminal of the voltage conversion circuit is connected to the first terminal of the third switch, and the second terminal of the third switch is connected to the positive output terminal of the bus; or, the third switch is connected to the The resistors are connected in parallel;

In the mains power supply mode, and when the voltage difference between the bus bar and the voltage conversion circuit is less than or equal to a preset threshold, the third switch is closed; in the battery power supply mode, the The third switch is off.
The device according to claim 1, wherein the switch comprises: a first switch, a second switch and balance components;

The positive pole of the second terminal of the voltage conversion circuit is respectively connected to the first terminal of the first switch and the first selection terminal of the second switch, and the second terminal of the first switch is connected to the balance element. The first end of the device is connected, the second end of the balance component is connected to the positive output end of the bus, the second selection end of the second switch is connected to the live wire of the AC power supply, and the second The fixed terminal of the switch is connected to the positive voltage input terminal, and the negative electrode of the second terminal of the voltage conversion circuit is connected to the negative output terminal of the bus;

The balance component is used to balance the voltage between the bus and the voltage conversion circuit;

In the mains power supply mode, the first switch is closed, and the fixed end of the second switch is connected to the second selection end of the second switch; in the battery power supply mode, the first switch When disconnected, the fixed end of the second switch is connected to the first selection end of the second switch.
The device according to claim 4, wherein the balance element is a resistor, and the switch further comprises: a third switch;

The positive pole of the second terminal of the voltage conversion circuit is connected to the first terminal of the third switch, and the second terminal of the third switch is connected to the positive output terminal of the bus; or, the third switch is connected to the The resistors are connected in parallel;

In the mains power supply mode, and when the voltage difference between the bus bar and the voltage conversion circuit is less than or equal to a preset threshold, the third switch is closed; in the battery power supply mode, the The third switch is off.
The device according to claim 1, wherein the switch comprises: a first switch, a second switch, a third switch, and a balance element;

The positive pole of the second terminal of the voltage conversion circuit is respectively connected to the first terminal of the first switch and the first terminal of the third switch, and the second terminal of the first switch is connected to the positive voltage input terminal , The first end of the second switch is connected to the live wire of the AC power supply, the second end of the second switch is connected to the positive voltage input end, and the second end of the third switch is connected to the The first end of the balance element is connected, the second end of the balance element is connected to the positive output end of the bus, and the negative pole of the second end of the voltage conversion circuit is connected to the negative output end of the bus;

The balance component is used to balance the voltage between the bus and the voltage conversion circuit;

In the mains power supply mode, the first switch is open, the second switch and the third switch are closed; in the battery power supply mode, the first switch is closed, and the second switch And the third switch is disconnected.
7. The device according to claim 6, wherein the balance element is a resistor, and the switch further comprises: a fourth switch;

The positive pole of the second terminal of the voltage conversion circuit is connected to the first terminal of the fourth switch, and the second terminal of the fourth switch is connected to the positive output terminal of the bus; or, the fourth switch is connected to the The resistors are connected in parallel;

In the mains power supply mode, and when the voltage difference between the bus bar and the voltage conversion circuit is less than or equal to a preset threshold, the fourth switch is closed; in the battery power supply mode, the The fourth switch is off.
The device according to any one of claims 2, 4, 6, wherein the balance component is any one of the following: a varistor, a thermistor with a negative temperature coefficient, and a third inductor.
The device according to any one of claims 1-7, wherein the voltage conversion circuit comprises: a fourth bridge arm, a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, a transformer, a third inductor, and a Two capacitors, third capacitors;

The fourth bridge arm includes a seventh switch tube and an eighth switch tube, and the first end of the seventh switch tube is connected to the first end of the eighth switch tube;

The fifth bridge arm includes a ninth switch tube and a tenth switch tube, and the first end of the ninth switch tube is connected to the first end of the tenth switch tube;

The sixth bridge arm includes an eleventh switch tube and a twelfth switch tube, and the first end of the eleventh switch tube is connected to the first end of the twelfth switch tube;

The seventh bridge arm includes a thirteenth switch tube and a fourteenth switch tube, and the first end of the thirteenth switch tube is connected to the first end of the fourteenth switch tube;

The fourth bridge arm is connected in parallel with the fifth bridge arm, the sixth bridge arm, the seventh bridge arm, and the third capacitor are connected in parallel, and the first end of the transformer is connected to the fourth bridge arm in parallel. The midpoint of the bridge arm is connected, the second end of the transformer is connected to the midpoint of the fifth bridge arm, and the third end of the transformer is connected to the fifth bridge through the third inductor and the second capacitor. The midpoint of the bridge arm is connected, and the fourth end of the transformer is connected with the midpoint of the sixth bridge arm;

The second terminal of the seventh switch tube is the anode of the first terminal of the voltage conversion circuit, and the second terminal of the eighth switch tube is the cathode of the first terminal of the voltage conversion circuit. The second terminal of the three-switch tube is the positive pole of the second terminal of the voltage conversion circuit, and the second terminal of the fourteenth switch tube is the negative pole of the second terminal of the voltage conversion circuit.
An uninterruptible power supply system, comprising: a commercial AC power supply, a load, and the three-arm topology device according to any one of claims 1 to 9;

Wherein, the live wire of the mains AC power supply is connected to the positive voltage input end of the three-arm topology device, and the neutral wire of the mains AC power supply is connected to the negative voltage input end of the three-arm topology device, so The output terminal of the three-arm topology device is connected to the load.
A method for controlling a three-arm topology device, wherein the method is used to control the three-arm topology device according to claim 2, and the method comprises:

In the mains power supply mode, the fixed terminal of the first switch is controlled to communicate with the first selection terminal of the first switch, and the second switch is closed; in the battery power mode, the fixed terminal of the first switch is controlled to be connected to the The second selection terminal of the first switch is connected, and the second switch is disconnected.
The method according to claim 11, further comprising:

In the mains power supply mode, when the voltage difference between the bus bar and the voltage conversion circuit of the three-leg topology device is less than or equal to the preset threshold, the third switch is controlled to close; in the battery power supply mode, the third switch is controlled to be closed; The third switch is off.
A method for controlling a three-arm topology device, wherein the method is used to control the three-arm topology device according to claim 4, and the method comprises:

In the mains power supply mode, the first switch is controlled to be closed, and the fixed end of the second switch is connected to the second selection end of the second switch; in the battery power supply mode, the first switch is controlled to open, and the first switch is controlled to be open. The fixed end of the second switch is connected with the first selection end of the second switch.
The method according to claim 13, further comprising:

In the mains power supply mode, when the voltage difference between the bus bar and the voltage conversion circuit of the three-leg topology device is less than or equal to the preset threshold, the third switch is controlled to close; in the battery power supply mode, the third switch is controlled to be closed; The third switch is off.
A control method of a three-arm topology device, the method is used to control the three-arm topology device as claimed in claim 6, the method further comprising:

In the mains power supply mode, the first switch is controlled to open, and the second switch and the third switch are closed; in the battery power supply mode, the first switch is controlled to be closed, and the second switch and the third switch are opened .
The method according to claim 15, further comprising:

In the mains power supply mode, when the voltage difference between the bus bar and the voltage conversion circuit of the three-leg topology device is less than or equal to the preset threshold, the fourth switch is controlled to close; in the battery power supply mode, the fourth switch is controlled to be closed; The fourth switch is off.