WO2020104068A1 - Dc-dc converter, bi-directional dc-dc converter, and uninterrupted power supply including same - Google Patents

Dc-dc converter, bi-directional dc-dc converter, and uninterrupted power supply including same

Info

Publication number
WO2020104068A1
WO2020104068A1 PCT/EP2019/025413 EP2019025413W WO2020104068A1 WO 2020104068 A1 WO2020104068 A1 WO 2020104068A1 EP 2019025413 W EP2019025413 W EP 2019025413W WO 2020104068 A1 WO2020104068 A1 WO 2020104068A1
Authority
WO
WIPO (PCT)
Prior art keywords
switching tube
inductor
diode
capacitor
converter
Prior art date
Application number
PCT/EP2019/025413
Other languages
French (fr)
Inventor
Hualiang Li
Huafen Ouyang
Dawei Zheng
Peihua YUAN
Xuegang LIU
Original Assignee
Eaton Intelligent Power Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eaton Intelligent Power Limited filed Critical Eaton Intelligent Power Limited
Publication of WO2020104068A1 publication Critical patent/WO2020104068A1/en

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
    • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
    • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
    • H02J9/061—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for DC powered loads
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/1557—Single ended primary inductor converters [SEPIC]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Definitions

  • FIG. 2 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 1 that are connected in parallel.
  • a negative electrode of a rechargeable battery B is connected to negative direct-current buses 121 and 122 of the two uninterrupted power supplies simultaneously.
  • each control device (not shown in FIG. 2) cannot independently control the voltage on a negative direct-current bus of a corresponding uninterrupted power supply.
  • the DC-DC converter 1 shown in FIG. 1 cannot be used in a plurality of uninterrupted power supplies connected in parallel.
  • the first switching tube when the first switching tube is turned on, the first inductor, the first switching tube, and the second inductor form a first current path, and the first capacitor, the first switching tube, the second capacitor, and the third inductor form a second current path; and when the first switching tube is turned off, the first diode, the third inductor, and the second diode form a third current path.
  • the DC-DC converter further comprises a control device for providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off.
  • a third switching tube connected in anti-parallel to the first diode; a second diode connected in anti-parallel to the first switching tube; and a third diode connected in anti-parallel to the second switching tube.
  • the bi-directional DC-DC converter further comprises: a third inductor, connected to the anode of the first diode;
  • FIG. 23 is a circuit diagram of the DC-DC converter shown in FIG. 22 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery.
  • FIG. 26 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 22 that are connected in parallel.
  • a period of the pulse-width modulation signal is T
  • a duty cycle of the pulse-width modulation signal is d
  • an on time and an off time of the insulated gate bipolar transistor T31 in one pulse-width modulation signal period are respectively Ton and Toff.
  • One period of the pulse-width modulation signal is used as an example for description below.
  • a collector of the insulated gate bipolar transistor T42 and an emitter of the insulated gate bipolar transistor T43 are respectively used for connecting to a positive electrode and a negative electrode of a direct-current power supply device (for example, a capacitor or a rechargeable battery), and one terminal of the inductor L41 and one terminal of the inductor L42 respectively serve as a positive output terminal and a negative output terminal of the DC- DC converter 4 and are used for connecting to a positive electrode and a negative electrode of another direct-current power supply device (for example, a capacitor or a rechargeable battery).
  • a direct-current power supply device for example, a capacitor or a rechargeable battery
  • the capacitor C61 has a large capacitance value so that the ripple voltage thereof can be ignored
  • the voltage at two terminals of the capacitor C61 is Uci
  • a value of the voltage between the positive direct-current bus 61 and the negative direct-current bus 62 is Udc
  • a voltage value of the rechargeable battery is Uo
  • the voltage at the direct-current bus 61 and the negative electrode of the rechargeable battery B is U2
  • the voltage at a node formed by connecting the inductor L61 , the capacitor C61 and the cathode of the diode D61 is UBI
  • the voltage at a node formed by connecting the capacitor C61 , the emitter of the insulated gate bipolar transistor T62 and the inductor L63 is UAI
  • inductance values of the inductor L61 and the inductor L63 are respectively Li and l_3
  • the current in the inductor L61 and the inductor L63 are respectively iu and ii_3, a period of the pulse-width

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The present invention provides a DC-DC converter, a bi-directional DC-DC converter and an uninterrupted power supply including the same. The DC-DC converter comprises: a first inductor, a first switching tube, and a second inductor connected in sequence; a first diode, a third inductor, and a second diode connected in sequence; a first capacitor connected between an anode of the second diode and a node formed by connecting one terminal of the first switching tube and the first inductor; and a second capacitor connected between a cathode of the first diode and a node formed by connecting the other terminal of the first switching tube and the second inductor. The DC-DC converter of the present invention can buck or boost charge a rechargeable battery, or make the rechargeable battery buck or boost discharge, and can be used in uninterrupted power supplies connected in parallel.

Description

DC-DC CONVERTER, BI-DIRECTIONAL DC-DC CONVERTER, AND UNINTERRUPTED POWER SUPPLY INCLUDING SAME
TECHNICAL FIELD
[0001 ] The present invention relates to the field of electronic circuits, and in particular, to a DC-DC converter, a bi-directional DC-DC converter, and an uninterrupted power supply including the same.
BACKGROUND
[0002] A DC-DC converter is an electrical device widely used in an uninterrupted power supply. An input terminal of the DC-DC converter is connected to a rechargeable battery, and an output terminal of the DC-DC converter is connected to positive and negative direct-current buses in the uninterrupted power supply. When a mains supply fails, the DC-DC converter boosts the direct current in the rechargeable battery and then outputs it to the positive and negative direct-current buses.
[0003] FIG. 1 is a circuit diagram of a first DC-DC converter in the prior art connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode. As shown in FIG. 1 , a DC-DC converter 1 includes an inductor L11 , a capacitor C11 , and a diode D12 connected in sequence between a positive direct-current bus 11 and a positive electrode of a rechargeable battery B, and an insulated gate bipolar transistor T 11 and an inductor L13. One terminal of the inductor L11 , one terminal of the capacitor C11 , and a collector of the insulated gate bipolar transistor T11 are connected, the other terminal of the capacitor C11 , an anode of the diode D12, and one terminal of the inductor L13 are connected, and a negative electrode of the rechargeable battery B, the other terminal of the inductor L13, and an emitter of the insulated gate bipolar transistor T11 are all connected to a negative direct-current bus 12. [0004] In FIG. 1 , at this time, the DC-DC converter 1 can only be controlled to transmit electric energy in the capacitor between the positive and negative direct-current buses to the rechargeable battery B, and cannot transmit electric energy in the rechargeable battery B to the capacitor between the positive and negative direct-current buses, and thus cannot achieve bi-directional energy transmission. In order to achieve bi-directional energy transmission, costs of circuit modules of the uninterrupted power supply will be increased.
[0005] In practical application of the uninterrupted power supply, in order to increase power density, a plurality of uninterrupted power supply power modules often need to be connected in parallel.
[0006] FIG. 2 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 1 that are connected in parallel. As shown in FIG. 2, a negative electrode of a rechargeable battery B is connected to negative direct-current buses 121 and 122 of the two uninterrupted power supplies simultaneously. As a result, each control device (not shown in FIG. 2) cannot independently control the voltage on a negative direct-current bus of a corresponding uninterrupted power supply. Thus, the DC-DC converter 1 shown in FIG. 1 cannot be used in a plurality of uninterrupted power supplies connected in parallel.
[0007] FIG. 3 is a circuit diagram of the DC-DC converter shown in FIG. 1 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode. As shown in FIG. 3, a cathode of the diode D12 is connected to a positive direct-current bus 11 , the other terminal of the inductor L11 is connected to a positive electrode of the rechargeable battery B, and a negative electrode of the rechargeable battery B, the emitter of the insulated gate bipolar transistor T11 , and one terminal of the inductor L13 are all connected to a negative direct-current bus 12. [0008] In FIG. 3, at this time, the DC-DC converter 1 can only be controlled to transmit electric energy in the rechargeable battery B to the capacitor between the positive and negative direct-current buses, and thus cannot achieve bi directional energy transmission. In order to achieve bi-directional energy transmission, costs of circuit modules of the uninterrupted power supply will be increased.
[0009] FIG. 4 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 3 that are connected in parallel. As shown in FIG. 4, a negative electrode of a rechargeable battery B is also connected to negative direct-current buses of the two uninterrupted power supplies. As a result, each control device (not shown in FIG. 4) also cannot independently control the voltage on a negative direct-current bus of a corresponding uninterrupted power supply. Thus, the DC-DC converter 1 cannot be used in a plurality of uninterrupted power supplies connected in parallel.
[0010] FIG. 5 is a circuit diagram of a second DC-DC converter in the prior art connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode. As shown in FIG. 5, the DC- DC converter 2 includes an insulated gate bipolar transistor T22, a capacitor C21 , and an inductor L21 connected in sequence between a positive direct- current bus 21 and a positive electrode of a rechargeable battery B, and an inductor L23 and a diode D21 . One terminal of the inductor L23, an emitter of the insulated gate bipolar transistor T22, and one terminal of the capacitor C21 are connected, a cathode of the diode D21 , the other terminal of the capacitor C21 , and one terminal of the inductor L21 are connected, and a negative electrode of the rechargeable battery B, an anode of the diode D21 , and the other terminal of the inductor L23 are all connected to a negative direct-current bus 22. [0011 ] In FIG. 5, at this time, the DC-DC converter 2 can only be controlled to transmit electric energy in the capacitor between the positive and negative direct-current buses to the rechargeable battery B, and cannot transmit electric energy in the rechargeable battery B to the capacitor between the positive and negative direct-current buses, and thus cannot achieve bi-directional energy transmission. In order to achieve bi-directional energy transmission, costs of circuit modules of the uninterrupted power supply will be increased.
[0012] FIG. 6 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 5 that are connected in parallel. As shown in FIG. 6, a negative electrode of a rechargeable battery B is connected to negative direct-current buses of the two uninterrupted power supplies simultaneously. As a result, each control device (not shown in FIG. 6) also cannot independently control the voltage on a negative direct-current bus of a corresponding uninterrupted power supply. Thus, the DC-DC converter 2 cannot be used in uninterrupted power supplies connected in parallel.
[0013] FIG. 7 is a circuit diagram of the DC-DC converter shown in FIG. 5 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode. As shown in FIG. 7, the other terminal of the inductor L21 is connected to a positive direct-current bus 21 , a collector of the insulated gate bipolar transistor T22 is connected to a positive electrode of the rechargeable battery B, and a negative electrode of the rechargeable battery B, the other terminal of the inductor L23, and the anode of the diode D21 are connected to a negative direct-current bus 22.
[0014] In FIG. 7, at this time, the DC-DC converter 2 can only be controlled to transmit electric energy in the rechargeable battery B to the capacitor between the positive and negative direct-current buses, and thus cannot achieve bi directional energy transmission. In order to achieve bi-directional energy transmission, costs of circuit modules of the uninterrupted power supply will be increased. [0015] FIG. 8 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 7 that are connected in parallel. As shown in FIG. 7, a negative electrode of a rechargeable battery B is connected to negative direct-current buses of the two uninterrupted power supplies. As a result, each control device (not shown in FIG. 7) also cannot independently control the voltage on a negative direct-current bus of a corresponding uninterrupted power supply. Thus, the DC-DC converter 2 cannot be used in uninterrupted power supplies connected in parallel.
SUMMARY
[0016] In view of the aforementioned technical problems existing in the prior art, the present invention provides a DC-DC converter, comprising:
a first inductor, a first switching tube, and a second inductor connected in sequence;
a first diode, a third inductor, and a second diode connected in sequence; a first capacitor, connected between an anode of the second diode and a node formed by connecting one terminal of the first switching tube and the first inductor; and
a second capacitor, connected between a cathode of the first diode and a node formed by connecting the other terminal of the first switching tube and the second inductor.
[0017] Preferably, when the first switching tube is turned on, the first inductor, the first switching tube, and the second inductor form a first current path, and the first capacitor, the first switching tube, the second capacitor, and the third inductor form a second current path; and when the first switching tube is turned off, the first diode, the third inductor, and the second diode form a third current path. [0018] Preferably, the first switching tube is a first insulated gate bipolar transistor, a collector of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the first inductor and the first capacitor, and an emitter of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the second inductor and the second capacitor, wherein the other terminal of the first inductor and the other terminal of the second inductor are respectively used for connecting to a positive electrode and a negative electrode of a first direct-current power supply device, and a cathode of the second diode and an anode of the first diode are respectively used for connecting to a positive electrode and a negative electrode of a second direct-current power supply device.
[0019] Preferably, the DC-DC converter further comprises:
a diode connected in anti-parallel to the first switching tube;
a second switching tube connected in anti-parallel to the first diode; and a third switching tube connected in anti-parallel to the second diode.
[0020] Preferably, the DC-DC converter further comprises a control device for providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off.
[0021 ] Preferably, the DC-DC converter further comprises a control device for controlling both the second switching tube and the third switching tube to turn off, and providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off; or
controlling the first switching tube to turn off, and providing the same pulse- width modulation signal to the second switching tube and the third switching tube, so that the second switching tube is alternately turned on and off and the third switching tube is alternately turned on and off.
[0022] The present invention further provides a DC-DC converter, comprising: a first switching tube, a first inductor, and a second switching tube connected in sequence;
a second inductor, a first diode, and a third inductor connected in sequence; a first capacitor, connected between a cathode of the first diode and one terminal of the first inductor; and
a second capacitor, connected between an anode of the first diode and the other terminal of the first inductor.
[0023] Preferably, when both the first switching tube and the second switching tube are turned on, the first switching tube, the first inductor, and the second switching tube form a first current path; and when both the first switching tube and the second switching tube are turned off, the second inductor, the first diode, and the third inductor form a second current path, and the first capacitor, the first inductor, the second capacitor, and the first diode form a third current path.
[0024] Preferably, the first switching tube is a first insulated gate bipolar transistor, and an emitter of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the first inductor and the first capacitor; and the second switching tube is a second insulated gate bipolar transistor, and a collector of the second insulated gate bipolar transistor is connected to a node formed by connecting the other terminal of the first inductor and the second capacitor, wherein a collector of the first insulated gate bipolar transistor and an emitter of the second insulated gate bipolar transistor are respectively used for connecting to a positive electrode and a negative electrode of a first direct-current power supply device, and the third inductor and the second inductor are respectively used for connecting to a positive electrode and a negative electrode of a second direct-current power supply device.
[0025] Preferably, the DC-DC converter further comprises:
a third switching tube connected in anti-parallel to the first diode; a second diode connected in anti-parallel to the first switching tube; and a third diode connected in anti-parallel to the second switching tube.
[0026] Preferably, the DC-DC converter further comprises a control device for providing the same pulse-width modulation signal to the first switching tube and the second switching tube, so that the first switching tube is alternately turned on and off and the second switching tube is alternately turned on and off.
[0027] Preferably, the DC-DC converter further comprises a control device for controlling the third switching tube to turn off, and providing the same pulse- width modulation signal to the first switching tube and the second switching tube, so that the first switching tube is alternately turned on and off and the second switching tube is alternately turned on and off; or
controlling both the first switching tube and the second switching tube to turn off, and providing a pulse-width modulation signal to the third switching tube so that the third switching tube is alternately turned on and off.
[0028] The present invention further provides a bi-directional DC-DC converter, comprising:
a first inductor and a first switching tube that are connected;
a first diode connected in anti-parallel to the first switching tube;
a second inductor and a second diode that are connected;
a second switching tube connected in anti-parallel to the second diode; and a first capacitor, wherein one terminal of the first capacitor is connected to a cathode of the first diode, and the other terminal of the first capacitor is connected to a node formed by connecting an anode of the second diode and one terminal of the second inductor, wherein
an anode of the first diode is electrically connected to the other terminal of the second inductor. [0029] Preferably, the first switching tube is a first insulated gate bipolar transistor, a collector of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the first inductor and the first capacitor, and an emitter of the first insulated gate bipolar transistor and the other terminal of the first inductor are respectively used for connecting to a negative electrode and a positive electrode of a first direct-current power supply device; and the second switching tube is a second insulated gate bipolar transistor, an emitter of the second insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the second inductor and the first capacitor, and a collector of the second insulated gate bipolar transistor and the other terminal of the second inductor are respectively used for connecting to a positive electrode and a negative electrode of a second direct-current power supply device.
[0030] Preferably, the bi-directional DC-DC converter further comprises: a third inductor, connected to the anode of the first diode;
a second capacitor, connected between the anode of the first diode and the other terminal of the second inductor;
a third diode, wherein a cathode of the third diode is connected to the other terminal of the second inductor; and
a third switching tube connected in anti-parallel to the third diode, wherein the first inductor and the third inductor are respectively used for connecting to a positive electrode and a negative electrode of a first direct-current power supply device, and a cathode of the second diode and an anode of the third diode are respectively used for connecting to a positive electrode and a negative electrode of a second direct-current power supply device.
[0031 ] Preferably, the bi-directional DC-DC converter further comprises a control device for
controlling the second switching tube to turn off, and providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off; or controlling the first switching tube to turn off, and providing a pulse-width modulation signal to the second switching tube so that the second switching tube is alternately turned on and off.
[0032] Preferably, the bi-directional DC-DC converter further comprises a control device for
controlling both the second switching tube and the third switching tube to turn off, and providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off; or
controlling the first switching tube to turn off, and providing the same pulse- width modulation signal to the second switching tube and the third switching tube, so that the second switching tube is alternately turned on and off and the third switching tube is alternately turned on and off.
[0033] The present invention further provides an uninterrupted power supply, comprising:
the DC-DC converter described above or the bi-directional DC-DC converter described above, wherein the DC-DC converter or the bi-directional DC-DC converter is connected between positive and negative direct-current buses and a rechargeable battery;
a power factor correction circuit, wherein an input terminal of the power factor correction circuit is used for connecting to an alternating-current power supply, and an output terminal of the power factor correction circuit is connected to the positive and negative direct-current buses; and
an inverter, wherein an input terminal of the inverter is connected to the positive and negative direct-current buses, and an output terminal of the inverter is used for providing an alternating current.
[0034] The DC-DC converter of the present invention can buck or boost charge a rechargeable battery, or make the rechargeable battery buck or boost discharge, and can be used in uninterrupted power supplies connected in parallel. The bi-directional DC-DC converter of the present invention can also achieve bi-directional energy transmission.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Embodiments of the present invention are further described below with reference to the accompanying drawings:
FIG. 1 is a circuit diagram of a first DC-DC converter in the prior art connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode.
FIG. 2 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 1 that are connected in parallel.
FIG. 3 is a circuit diagram of the DC-DC converter shown in FIG. 1 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode.
FIG. 4 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 3 that are connected in parallel.
FIG. 5 is a circuit diagram of a second DC-DC converter in the prior art connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode.
FIG. 6 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 5 that are connected in parallel.
FIG. 7 is a circuit diagram of the DC-DC converter shown in FIG. 5 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode.
FIG. 8 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 7 that are connected in parallel.
FIG. 9 is a circuit diagram of a DC-DC converter according to a first embodiment of the present invention.
FIG. 10 and FIG. 11 are circuit diagrams of the DC-DC converter shown in FIG. 9 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode. FIG. 12 and FIG. 13 are circuit diagrams of the DC-DC converter shown in FIG. 9 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode.
FIG. 14 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 10 that are connected in parallel.
FIG. 15 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 12 that are connected in parallel.
FIG. 16 is a circuit diagram of a DC-DC converter according to a second embodiment of the present invention.
FIG. 17 is a circuit diagram of the DC-DC converter shown in FIG. 16 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode.
FIG. 18 and FIG. 19 are circuit diagrams of the DC-DC converter shown in FIG. 16 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode.
FIG. 20 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 17 that are connected in parallel.
FIG. 21 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 18 that are connected in parallel.
FIG. 22 is a circuit diagram of a DC-DC converter according to a third embodiment of the present invention.
FIG. 23 is a circuit diagram of the DC-DC converter shown in FIG. 22 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery.
FIG. 24 is an equivalent circuit diagram of the DC-DC converter shown in FIG. 23 in a charging mode.
FIG. 25 is an equivalent circuit diagram of the DC-DC converter shown in FIG. 23 in a discharging mode.
FIG. 26 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 22 that are connected in parallel.
FIG. 27 is a circuit diagram of a bi-directional DC-DC converter according to a fourth embodiment of the present invention. FIG. 28 is a circuit diagram of the bi-directional DC-DC converter shown in FIG. 27 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery.
FIG. 29 and FIG. 30 are equivalent circuit diagrams of the bi-directional DC- DC converter in a charging mode.
FIG. 31 and FIG. 32 are equivalent circuit diagrams of the bi-directional DC- DC converter in a discharging mode.
FIG. 33 is a circuit diagram of a bi-directional DC-DC converter according to a fifth embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below through specific embodiments with reference to the accompanying drawings.
[0037] FIG. 9 is a circuit diagram of a DC-DC converter according to a first embodiment of the present invention. The DC-DC converter 3 includes an inductor L31 , an insulated gate bipolar transistor T31 , and an inductor L32 connected in sequence, a diode D33, an inductor L33, and a diode D32 connected in sequence, and a capacitor C31 and a capacitor C32. One terminal of the capacitor C31 is connected to a node formed by connecting the inductor L31 and a collector of the insulated gate bipolar transistor T31 , and the other terminal of the capacitor C31 is connected to an anode of the diode D32; and one terminal of the capacitor C32 is connected to a node formed by connecting one terminal of the inductor L32 and an emitter of the insulated gate bipolar transistor T31 , and the other terminal of the capacitor C32 is connected to a cathode of the diode D33.
[0038] One terminal of the inductor L31 and the other terminal of the inductor L32 are respectively used for connecting to a positive electrode and a negative electrode of a direct-current power supply device (for example, a capacitor or a rechargeable battery), and a cathode of the diode D32 and an anode of the diode D33 respectively serve as a positive output terminal and a negative output terminal of the DC-DC converter 3 and are used for connecting to a positive electrode and a negative electrode of another direct-current power supply device (for example, a capacitor or a rechargeable battery).
[0039] With reference to FIG. 1 and FIG. 9, the DC-DC converter 3 differs from the DC-DC converter 1 shown in FIG. 1 in that the DC-DC converter 3 further includes the inductor L32 connected to the emitter of the insulated gate bipolar transistor T31 , the capacitor C32 connected between the emitter of the insulated gate bipolar transistor T31 and the inductor L33, and the diode D33, where the cathode of the diode D33 is connected to a node formed by connecting the capacitor C32 and the inductor L33.
[0040] The operating principles of the DC-DC converter 3 in a charging mode will be described below with reference to FIG. 10 and FIG. 11 .
[0041 ] FIG. 10 and FIG. 11 are circuit diagrams of the DC-DC converter shown in FIG. 9 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode. As shown in FIG. 10 and FIG. 11 , the inductor L31 and the inductor L32 are respectively connected to a positive direct-current bus 31 and a negative direct-current bus 32, and the cathode of the diode D32 and the anode of the diode D33 are respectively connected to a negative electrode and a positive electrode of a rechargeable battery B.
[0042] A pulse-width modulation signal is provided to a gate of the insulated gate bipolar transistor T31 (namely, a control terminal thereof) so that the insulated gate bipolar transistor T31 is alternately turned on and off. [0043] When the insulated gate bipolar transistor T31 is turned on, as shown in FIG. 10, the positive direct-current bus 31 , the inductor L31 , the insulated gate bipolar transistor T31 , the inductor L32, and the negative direct-current bus 32 form a current path, and the current direction thereof is indicated by the dashed single-headed arrow in FIG. 10. At this time, the inductor L31 and the inductor L32 store energy. At the same time, the inductor L33, the capacitor C31 , the insulated gate bipolar transistor T31 and the capacitor C32 form another current path, and the current direction thereof is indicated by the dashed double-headed arrow in FIG. 10. At this time, the capacitor C31 and the capacitor C32 release and store energy in the inductor L33.
[0044] When the insulated gate bipolar transistor T31 is turned off, as shown in FIG. 11 , the positive direct-current bus 31 , the inductor L31 , the capacitor C31 , the diode D32, the rechargeable battery B, the diode D33, the capacitor C32, the inductor L32, and the negative direct-current bus 32 form a current path, and the current direction thereof is indicated by the dashed single headed arrow in FIG. 11 . At this time, the inductor L31 and the inductor L32 release and store energy in the capacitor C31 , the rechargeable battery B and the capacitor C32. At the same time, the diode D33, the inductor L33, the diode D32 and the rechargeable battery B form another current path, and the current direction thereof is indicated by the dashed double-headed arrow in FIG. 11 . At this time, the inductor L33 releases and stores energy in the rechargeable battery B.
[0045] With reference to FIG. 10 and FIG. 11 , electric energy in the capacitor between the positive direct-current bus 31 and the negative direct-current bus 32 is finally stored in the rechargeable battery B, thereby achieving charging of the rechargeable battery B.
[0046] Assume that the capacitor C31 and the capacitor C32 have large capacitance values so that ripple voltages thereof can be ignored, and the voltages at two terminals of the capacitors C31 and C32 are respectively Uci and Uc2, a value of the voltage between the positive and negative direct- current buses is Udc, a voltage value of the rechargeable battery is Uo, the voltage at a node formed by connecting the inductor L31 , the capacitor C31 , and the collector of the insulated gate bipolar transistor T31 is UBI , the voltage at a node formed by connecting the capacitor C31 , the anode of the diode D32, and the inductor L33 is UAI , the voltage at a node formed by connecting the inductor L32, the capacitor C32, and the emitter of the insulated gate bipolar transistor T31 is UB2, and the voltage at a node formed by connecting the capacitor C32, the cathode of the diode D33, and the inductor L33 is UA2. A period of the pulse-width modulation signal is T, a duty cycle of the pulse-width modulation signal is d, and an on time and an off time of the insulated gate bipolar transistor T31 in one pulse-width modulation signal period are respectively Ton and Toff. One period of the pulse-width modulation signal is used as an example for description below.
[0047] When the insulated gate bipolar transistor T31 is turned on, the following equations are satisfied:
Figure imgf000018_0001
Then
Figure imgf000018_0002
[0048] When the insulated gate bipolar transistor T31 is turned off, the following equations are satisfied:
Figure imgf000018_0003
Then
Figure imgf000018_0004
[0049] In one switching period T, the following equations are satisfied:
Figure imgf000019_0001
[0050] The average voltage of the inductor L33 in one switching period is 0, and thus:
Figure imgf000019_0002
[0051] When the duty cycle d is less than 0.5, buck charging of the rechargeable battery B is achieved. When the duty cycle d is greater than 0.5, boost charging of the rechargeable battery B is achieved.
[0052] The operating principles of the DC-DC converter 3 in a discharging mode are described below with reference to FIG. 12 and FIG. 13. [0053] FIG. 12 and FIG. 13 are circuit diagrams of the DC-DC converter shown in FIG. 9 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode. The cathode of the diode D32 in the DC-DC converter 3 is connected to a positive direct-current bus 31 , the anode of the diode D33 is connected to a negative direct-current bus 32, and the inductor L31 and the inductor L32 are respectively connected to a positive electrode and a negative electrode of the rechargeable battery B.
[0054] A pulse-width modulation signal is provided to a gate of the insulated gate bipolar transistor T31 so that the insulated gate bipolar transistor T31 is alternately turned on and off.
[0055] When the insulated gate bipolar transistor T31 is turned on, as shown in FIG. 12, the rechargeable battery B, the inductor L31 , the insulated gate bipolar transistor T31 and the inductor L32 form a current path, and the current direction thereof is indicated by the dashed single-headed arrow in FIG. 12. At this time, electric energy in the rechargeable battery B is stored in the inductor L31 and the inductor L32. At the same time, the inductor L33, the capacitor C31 , the insulated gate bipolar transistor T31 and the capacitor C32 form another current path, and the current direction thereof is indicated by the dashed double-headed arrow in FIG. 12. At this time, the capacitor C31 and the capacitor C32 release and store energy in the inductor L33.
[0056] When the insulated gate bipolar transistor T31 is turned off, as shown in FIG. 13, the rechargeable battery B, the inductor L31 , the capacitor C31 , the diode D32, the positive direct-current bus 31 , the negative direct-current bus 32, the diode D33, the capacitor C32 and the inductor L32 form a current path, the current direction thereof is indicated by the dashed single-headed arrow in FIG. 13. The inductor L31 and the inductor L32 release and store energy in a capacitor between the positive direct-current bus 31 and the negative direct- current bus 32. At the same time, the negative direct-current bus 32, the diode D33, the inductor L33, the diode D32 and the positive direct-current bus 31 form another current path, the current direction thereof is indicated by the dashed double-headed arrow in FIG. 13. The inductor L33 releases and stores energy in the capacitor between the positive direct-current bus 31 and the negative direct-current bus 32.
[0057] With reference to FIG. 12 and FIG. 13, electric energy in the rechargeable battery B is finally stored in the capacitor between the positive direct-current bus 31 and the negative direct-current bus 32, thereby achieving discharging of the rechargeable battery B.
[0058] Assume that a value of the voltage between the positive direct-current bus 31 and the negative direct-current bus 32 is Udc, and a voltage value of the rechargeable battery B is Uo. Based on the same derivation as above, the following is obtained:
Udc/Uo=d/(1 -d).
[0059] When the duty cycle d is less than 0.5, buck discharging of the rechargeable battery B is achieved; when the duty cycle d is greater than 0.5, boost discharging of the rechargeable battery B is achieved.
[0060] FIG. 14 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 10 that are connected in parallel. As shown in FIG. 14, a negative electrode of a rechargeable battery B is connected to a negative direct-current bus 321 of one uninterrupted power supply through a diode, a capacitor and an inductor in sequence, and meanwhile is connected to a negative direct-current bus 322 of the other uninterrupted power supply through a diode, a capacitor and an inductor in sequence. The negative direct-current buses 321 and 322 of the two uninterrupted power supplies are isolated from each other. Each control device (not shown in FIG. 14) can independently charge the rechargeable battery B using electric energy in a capacitor between positive and negative direct- current buses of a corresponding uninterrupted power supply, so as to independently control the voltage on a negative direct-current bus of each uninterrupted power supply.
[0061 ] FIG. 15 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 12 that are connected in parallel. As shown in FIG. 15, a negative direct-current bus 321 ' of one uninterrupted power supply is connected to a negative electrode of a rechargeable battery B through a diode, a capacitor and an inductor in sequence, and a negative direct-current bus 322' of the other uninterrupted power supply is connected to the negative electrode of the rechargeable battery B through a diode, a capacitor and an inductor in sequence. The negative direct-current buses 321 ' and 322' of the two uninterrupted power supplies are isolated from each other. Each control device (not shown in FIG. 15) can make the rechargeable battery B discharge and store electricity in a capacitor between positive and negative direct-current buses of a corresponding uninterrupted power supply, so as to independently control the voltage on a negative direct-current bus of each uninterrupted power supply.
[0062] FIG. 16 is a circuit diagram of a DC-DC converter according to a second embodiment of the present invention. As shown in FIG. 16, the DC-DC converter 4 includes an insulated gate bipolar transistor T42, an inductor L43 and an insulated gate bipolar transistor T43 connected in sequence, an inductor L42, a diode D41 and an inductor L41 connected in sequence, and a capacitor C41 and a capacitor C42. One terminal of the capacitor C41 is connected to an emitter of the insulated gate bipolar transistor T42, the other terminal of the capacitor C41 is connected to a cathode of the diode D41 , one terminal of the capacitor C42 is connected to a collector of the insulated gate bipolar transistor T43, and the other terminal of the capacitor C42 is connected to an anode of the diode D41 . [0063] A collector of the insulated gate bipolar transistor T42 and an emitter of the insulated gate bipolar transistor T43 are respectively used for connecting to a positive electrode and a negative electrode of a direct-current power supply device (for example, a capacitor or a rechargeable battery), and one terminal of the inductor L41 and one terminal of the inductor L42 respectively serve as a positive output terminal and a negative output terminal of the DC- DC converter 4 and are used for connecting to a positive electrode and a negative electrode of another direct-current power supply device (for example, a capacitor or a rechargeable battery).
[0064] With reference to FIG. 5 and FIG. 16, the DC-DC converter 4 differs from the DC-DC converter 2 shown in FIG. 5 in that the DC-DC converter 4 further includes an insulated gate bipolar transistor T43, a capacitor C42 and an inductor L42, where the capacitor C42 is connected between one terminal of the inductor L43 and the anode of the diode D41 , a collector of the insulated gate bipolar transistor T43 is connected to a node formed by connecting one terminal of the inductor L43 and the capacitor C42, and the inductor L42 is connected to the anode of the diode D41 .
[0065] The operating principles of the DC-DC converter 4 in a charging mode and a discharging mode will be described below with reference to FIGs. 17 to 19.
[0066] FIG. 17 is a circuit diagram of the DC-DC converter shown in FIG. 16 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a charging mode. The collector of the insulated gate bipolar transistor T42 is connected to a positive direct-current bus 41 , the emitter of the insulated gate bipolar transistor T43 is connected to a negative direct-current bus 42, and the inductor L41 and the inductor L42 are respectively connected to a positive electrode and a negative electrode of the rechargeable battery B. [0067] FIG. 18 and FIG. 19 are circuit diagrams of the DC-DC converter shown in FIG. 16 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery and in a discharging mode. The collector of the insulated gate bipolar transistor T42 and the emitter of the insulated gate bipolar transistor T43 are respectively connected to a positive electrode and a negative electrode of a rechargeable battery B, and the inductor L41 and the inductor L42 are respectively connected to a positive direct-current bus 41 and a negative direct-current bus 42.
[0068] The operating principles of the DC-DC converter 4 in a charging mode and a discharging mode are the same, and only the operating principles of the DC-DC converter 4 in a discharging mode are described herein with reference to FIG. 18 and FIG. 19. In the discharging mode, the same pulse-width modulation signal is provided to gates of the insulated gate bipolar transistors T42 and T43, so that the insulated gate bipolar transistor T42 is alternately turned on and off and the insulated gate bipolar transistor T43 is alternately turned on and off.
[0069] When the insulated gate bipolar transistors T42 and T43 are both turned on, as shown in FIG. 18, the rechargeable battery B, the insulated gate bipolar transistor T42, the inductor L43, and the insulated gate bipolar transistor T43 form a current path, the current direction thereof is indicated by the dashed single-headed arrow in FIG. 18. Electric energy in the rechargeable battery B is stored in the inductor L43. At the same time, the rechargeable battery B, the insulated gate bipolar transistor T42, the capacitor C41 , the inductor L41 , the positive direct-current bus 41 , the negative direct-current bus 42, the inductor L42, the capacitor C42 and the insulated gate bipolar transistor T43 form another current path, the current direction thereof is indicated by the dashed double-headed arrow in FIG. 18. At this time, the rechargeable battery B, the capacitor C41 and the capacitor C42 release and store energy in the inductor L41 , a capacitor between the positive direct-current bus 41 and the negative direct-current bus 42, and the inductor L42. [0070] When the insulated gate bipolar transistors T42 and T43 are both turned off, as shown in FIG. 19, the inductor L43, the capacitor C42, the diode D41 and the capacitor C41 form a current path, the current direction thereof is indicated by the dashed single-headed arrow in FIG. 19. At this time, the inductor L43 releases and stores energy in the capacitor C41 and the capacitor C42. At the same time, the negative direct-current bus 42, the inductor L42, the diode D41 , the inductor L41 , and the positive direct-current bus 41 form another current path, the current direction thereof is indicated by the dashed double-headed arrow in FIG. 19. At this time, the inductor L41 and the inductor L42 release and store energy in a capacitor between the positive direct-current bus 41 and the negative direct-current bus 42.
[0071 ] With reference to FIG. 18 and FIG. 19, electric energy in the rechargeable battery B is finally stored in the capacitor between the positive direct-current bus 41 and the negative direct-current bus 42.
[0072] Assume that a value of the voltage between the positive direct-current bus 41 and the negative direct-current bus 42 is Udc, a voltage value of the rechargeable battery B is Uo, the voltage at a node formed by connecting the inductor L41 , the capacitor C41 , and the cathode of the diode D41 is U BI , the voltage at a node formed by connecting the inductor L42, the capacitor C42, and the anode of the diode D41 is UB2, the voltage at a node formed by connecting the capacitor C41 , the emitter of the insulated gate bipolar transistor T42, and the inductor L43 is UAI , the voltage at a node formed by connecting the capacitor C42, the collector of the insulated gate bipolar transistor T43, and the inductor L43 is UA2, inductance values of the inductor L41 , the inductor L42, and the inductor L43 are respectively Li , l_2, and l_3, the current in the inductor L43 is ii_3, the current in the inductor L41 , and the inductor L42 is ILI L2, the voltages of the capacitor C41 and the capacitor C42 are respectively Uci and Uc2, a period of the pulse-width modulation signal is T, a duty cycle of the pulse-width modulation signal is d, and an on time and an off time of the insulated gate bipolar transistors T42 and T43 in one pulse- width modulation signal period are respectively Ton and Toff. One period of the pulse-width modulation signal is used as an example for description. [0073] When the insulated gate bipolar transistors T42 and T43 are both turned on, the following equations are satisfied:
Figure imgf000026_0001
[0074] When the insulated gate bipolar transistors T42 and T43 are both turned off, the following equations are satisfied:
Figure imgf000026_0002
Figure imgf000027_0001
[0075] The average voltage of the inductor L43 in one switching period is 0, and thus the following equations are satisfied:
Figure imgf000027_0002
[0076] When the duty cycle d is less than 0.5, buck discharging of the rechargeable battery B is achieved; when the duty cycle d is greater than 0.5, boost discharging of the rechargeable battery B is achieved. [0077] FIG. 20 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 17 that are connected in parallel. As shown in FIG. 20, each control device (not shown in FIG. 20) can independently charge the rechargeable battery B using electric energy in a capacitor between positive and negative direct-current buses of a corresponding uninterrupted power supply, so as to independently control the voltage on a negative direct-current bus of each uninterrupted power supply.
[0078] FIG. 21 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 18 that are connected in parallel. As shown in FIG. 21 , each control device (not shown in FIG. 21 ) can store electric energy in the rechargeable battery B in a capacitor between positive and negative direct-current buses of a corresponding uninterrupted power supply, so as to independently control the voltage on a negative direct-current bus of each uninterrupted power supply.
[0079] FIG. 22 is a circuit diagram of a DC-DC converter according to a third embodiment of the present invention. As shown in FIG. 22, the DC-DC converter 5 differs from the DC-DC converter 3 shown in FIG. 9 in that the DC- DC converter 5 further includes a diode D51 connected in anti-parallel to an insulated gate bipolar transistor T51 , and insulated gate bipolar transistors T52 and T53 respectively connected in anti-parallel to diodes D52 and D53.
[0080] In addition, the DC-DC converter 5 differs from the DC-DC converter 4 shown in FIG. 16 in that the DC-DC converter 5 further includes the insulated gate bipolar transistor T51 connected in anti-parallel to the diode D51 , and the diodes D52 and D53 respectively connected in anti-parallel to the insulated gate bipolar transistors T52 and T53.
[0081 ] The other terminal of the inductor L51 and the other terminal of the inductor L52 are respectively used for connecting to a positive electrode and a negative electrode of a direct-current power supply device (for example, a capacitor or a rechargeable battery), and a cathode of the diode D52 and an anode of the diode D53 respectively serve as a positive output terminal and a negative output terminal of the DC-DC converter 5 and are used for connecting to a positive electrode and a negative electrode of another direct-current power supply device (for example, a capacitor or a rechargeable battery). Or, the cathode of the diode D52 and the anode of the diode D53 are respectively used for connecting to a positive electrode and a negative electrode of a direct- current power supply device (for example, a capacitor or a rechargeable battery), and the other terminal of the inductor L51 and the other terminal of the inductor L52 respectively serve as a positive output terminal and a negative output terminal of the DC-DC converter 5 and are used for connecting to a positive electrode and a negative electrode of another direct-current power supply device (for example, a capacitor or a rechargeable battery).
[0082] FIG. 23 is a circuit diagram of the DC-DC converter shown in FIG. 22 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery. As shown in FIG. 23, one terminal of the inductor L51 and one terminal of the inductor L52 are respectively connected to a positive direct-current bus 51 and a negative direct-current bus 52, the cathode of the diode D52 and a collector of the insulated gate bipolar transistor T52 are connected to a positive electrode of a rechargeable battery B, and the anode of the diode D53 and an emitter of the insulated gate bipolar transistor T53 are connected to a negative electrode of the rechargeable battery B.
[0083] The operating principles of the DC-DC converter 5 in a charging mode and a discharging mode are described respectively below with reference to FIG. 24 and FIG. 25.
[0084] In the charging mode, a control device (not shown in FIG. 23) controls both the insulated gate bipolar transistors T52 and T53 to turn off, and provides a pulse-width modulation signal to a gate of the insulated gate bipolar transistor T51 so that the insulated gate bipolar transistor T51 is alternately turned on and off. FIG. 24 is an equivalent circuit diagram of the DC-DC converter shown in FIG. 23 in a charging mode, which is the same as the circuit shown in FIG. 10 and FIG. 11 . The specific control process is not described herein again, and buck charging or boost charging of the rechargeable battery B can also be achieved.
[0085] In the discharging mode, a control device (not shown in FIG. 23) controls the insulated gate bipolar transistor T51 to turn off, and provides the same pulse-width modulation signal to gates of the insulated gate bipolar transistors T52 and T53, so that the insulated gate bipolar transistor T52 is alternately turned on and off and the insulated gate bipolar transistor T53 is alternately turned on and off. FIG. 25 is an equivalent circuit diagram of the DC-DC converter shown in FIG. 23 in a discharging mode, which is the same as the circuit shown in FIGs. 18 to 19. The specific control process is not described herein again, and boost discharging or buck discharging of the rechargeable battery B can also be achieved.
[0086] With reference to FIG. 24 and FIG. 25, the DC-DC converter 5 in this embodiment is a bi-directional DC-DC converter and does not need to be additionally connected to a charger or a direct-current converter, thereby saving costs. Boost discharging or buck discharging of the rechargeable battery B can be achieved, and buck charging or boost charging of the rechargeable battery B can also be achieved. During charging of the rechargeable battery B, a duty cycle of a pulse-width modulation signal is changed so that a capacitor between positive and negative direct-current buses can be deeply discharged and charge the rechargeable battery B at a capacitor voltage of approximately 0 volt without producing any impact current.
[0087] FIG. 26 is a circuit diagram of two uninterrupted power supplies including the DC-DC converter shown in FIG. 22 that are connected in parallel. Each control device (not shown in FIG. 26) can separately control a DC-DC converter in a corresponding uninterrupted power supply, and the specific control manner thereof is not described herein again.
[0088] FIG. 27 is a circuit diagram of a bi-directional DC-DC converter according to a fourth embodiment of the present invention. As shown in FIG. 27, the bi-directional DC-DC converter 6 includes an inductor L61 and an insulated gate bipolar transistor T61 that are connected, a diode D61 connected in anti-parallel to the insulated gate bipolar transistor T61 , an inductor L63 and a diode D62 that are connected, an insulated gate bipolar transistor T62 connected in anti-parallel to the diode D62, and a capacitor C61 . One terminal of the capacitor C61 is connected to a collector of the insulated gate bipolar transistor T61 (namely, a cathode of the diode D61 ), the other terminal of the capacitor C61 is connected to a node formed by connecting an emitter of the insulated gate bipolar transistor T62 (namely, an anode of the diode D62) and the inductor L63, and an anode of the diode D61 is electrically connected to the other terminal of the inductor L63.
[0089] One terminal of the inductor L61 and the anode of the diode D61 are respectively used for connecting to a positive electrode and a negative electrode of a direct-current power supply device (for example, a capacitor or a rechargeable battery), and a cathode of the diode D62 and the other terminal of the inductor L63 respectively serve as a positive output terminal and a negative output terminal of the bi-directional DC-DC converter 6 and are used for connecting to a positive electrode and a negative electrode of another direct-current power supply device (for example, a capacitor or a rechargeable battery). Or, the cathode of the diode D62 and the other terminal of the inductor L63 are respectively used for connecting to a positive electrode and a negative electrode of a direct-current power supply device (for example, a capacitor or a rechargeable battery), and one terminal of the inductor L61 and the anode of the diode D61 respectively serve as a positive output terminal and a negative output terminal of the bi-directional DC-DC converter 6 and are used for connecting to a positive electrode and a negative electrode of another direct-current power supply device (for example, a capacitor or a rechargeable battery).
[0090] With reference to FIG. 1 and FIG. 27, the bi-directional DC-DC converter 6 differs from the DC-DC converter 1 shown in FIG. 1 in that the bi directional DC-DC converter 6 further includes the diode D61 connected in anti-parallel to the insulated gate bipolar transistor T61 and the insulated gate bipolar transistor T62 connected in anti-parallel to the diode D62.
[0091 ] In addition, with reference to FIG. 5 and FIG. 27, the bi-directional DC- DC converter 6 differs from the DC-DC converter 2 shown in FIG. 5 in that the bi-directional DC-DC converter 6 further includes the diode D62 connected in anti-parallel to the insulated gate bipolar transistor T62 and the insulated gate bipolar transistor T61 connected in anti-parallel to the diode D61 .
[0092] FIG. 28 is a circuit diagram of the bi-directional DC-DC converter shown in FIG. 27 connected between direct-current buses of an uninterrupted power supply and a rechargeable battery. The inductor L61 is connected to a positive direct-current bus 61 , the cathode of the diode D62 and the collector of the insulated gate bipolar transistor T62 are connected to a positive electrode of the rechargeable battery B, and the negative electrode of the rechargeable battery B, the inductor L63, the anode of the diode D61 , and the emitter of the insulated gate bipolar transistor T61 are all connected to a negative direct-current bus 62.
[0093] The operating principles of the bi-directional DC-DC converter 6 in a charging mode and a discharging mode are respectively described below with reference to equivalent circuit diagrams of the bi-directional DC-DC converter 6.
[0094] FIG. 29 and FIG. 30 are equivalent circuit diagrams of the bi-directional DC-DC converter 6 in a charging mode. [0095] In the charging mode, a control device (not shown in FIG. 28) controls the insulated gate bipolar transistor T62 to turn off, and provides a pulse-width modulation signal to a gate of the insulated gate bipolar transistor T61 so that the insulated gate bipolar transistor T61 is alternately turned on and off.
[0096] As shown in FIG. 29, when the insulated gate bipolar transistor T61 is turned on, the positive direct-current bus 61 , the inductor L61 , the insulated gate bipolar transistor T61 , and the negative direct-current bus 62 form a current path, the current direction thereof is indicated by the dashed single headed arrow in FIG. 29. At this time, the inductor L61 stores energy. At the same time, the inductor L63, the capacitor C61 , and the insulated gate bipolar transistor T61 form another current path, the current direction thereof is indicated by the dashed double-headed arrow in FIG. 29. At this time, the capacitor C61 releases and stores energy in the inductor L63.
[0097] As shown in FIG. 30, when the insulated gate bipolar transistor T61 is turned off, the positive direct-current bus 61 , the inductor L61 , the capacitor C61 , the diode D62, the rechargeable battery B and the negative direct-current bus 62 form a current path, the current direction thereof is indicated by the dashed single-headed arrow in FIG. 30. At this time, the inductor L61 releases and stores energy in the capacitor C61 and the rechargeable battery B. At the same time, the inductor L63, the diode D62 and the rechargeable battery B form another current path, the current direction thereof is indicated by the dashed double-headed arrow in FIG. 30. At this time, the inductor L63 releases and stores energy in the rechargeable battery B.
[0098] With reference to FIG. 29 and FIG. 30, electric energy in the capacitor between the positive direct-current bus 61 and the negative direct-current bus 62 is finally stored in the rechargeable battery B, thereby achieving charging of the rechargeable battery B. [0099] Assume that the capacitor C61 has a large capacitance value so that the ripple voltage thereof can be ignored, the voltage at two terminals of the capacitor C61 is Uci, a value of the voltage between the positive direct-current bus 61 and the negative direct-current bus 62 is Udc, a voltage value of the rechargeable battery B is Uo, the voltage at the negative direct-current bus 62, the negative electrode of the rechargeable battery B, and the emitter of the insulated gate bipolar transistor T61 is U2, the voltage at a node formed by connecting the inductor L61 , the capacitor C61 , and the collector of the insulated gate bipolar transistor T61 is UBI , the voltage at a node formed by connecting the capacitor C61 , the anode of the diode D62, and the inductor L63 is UAI , a period of the pulse-width modulation signal is T, a duty cycle of the pulse-width modulation signal is d, and an on time and an off time of the insulated gate bipolar transistor T61 in one pulse-width modulation signal period are respectively Ton and Toff. One period of the pulse-width modulation signal is used as an example for description.
[0100] When the insulated gate bipolar transistor T61 is turned on, the following equations are satisfied:
Figure imgf000034_0001
[0101 ] When the insulated gate bipolar transistor T61 is turned off, the following equations are satisfied:
Figure imgf000034_0002
[0102] In one switching period, the following equations are satisfied:
Figure imgf000035_0001
[0103] The average voltage of the inductor L63 in one switching period is 0, and thus:
Figure imgf000035_0002
[0104] Thus, Uo/Udc=d/(1 -d). When the duty cycle d is less than 0.5, buck charging of the rechargeable battery B is achieved. When the duty cycle d is greater than 0.5, boost charging of the rechargeable battery B is achieved.
[0105] FIG. 31 and FIG. 32 are equivalent circuit diagrams of the bi-directional DC-DC converter 6 in a discharging mode. [0106] In the discharging mode, a control device (not shown in FIG. 28) controls the insulated gate bipolar transistor T61 to turn off, and provides a pulse-width modulation signal to a gate of the insulated gate bipolar transistor T62 so that the insulated gate bipolar transistor T62 is alternately turned on and off.
[0107] As shown in FIG. 31 , when the insulated gate bipolar transistor T62 is turned on, the rechargeable battery B, the insulated gate bipolar transistor T62, and the inductor L63 form a current path, the current direction thereof is indicated by the dashed single-headed arrow in FIG. 31 . At this time, the inductor L63 stores energy. At the same time, the rechargeable battery B, the insulated gate bipolar transistor T62, the capacitor C61 , the inductor L61 , the positive direct-current bus 61 and the negative direct-current bus 62 form another current path, the current direction thereof is indicated by the dashed double-headed arrow in FIG. 31 . At this time, the rechargeable battery B and the capacitor C61 release and store energy in the inductor L61 and a capacitor between the positive direct-current bus 61 and the negative direct-current bus 62.
[0108] As shown in FIG. 32, when the insulated gate bipolar transistor T62 is turned off, the inductor L63, the diode D61 , and the capacitor C61 form a current path, the current direction thereof is indicated by the dashed single headed arrow in FIG. 32. At this time, the inductor L63 releases and stores energy in the capacitor C61 . At the same time, the inductor L61 , the positive direct-current bus 61 , the negative direct-current bus 62, and the diode D61 form another current path, the current direction thereof is indicated by the dashed double-headed arrow in FIG. 32. At this time, the inductor L61 releases and stores energy in a capacitor between the positive direct-current bus 61 and the negative direct-current bus 62.
[0109] With reference to FIG. 31 and FIG. 32, electric energy in the rechargeable battery B is finally stored in the capacitor between the positive direct-current bus 61 and the negative direct-current bus 62, thereby achieving discharging of the rechargeable battery B.
[0110] Assume that the capacitor C61 has a large capacitance value so that the ripple voltage thereof can be ignored, the voltage at two terminals of the capacitor C61 is Uci, a value of the voltage between the positive direct-current bus 61 and the negative direct-current bus 62 is Udc, a voltage value of the rechargeable battery is Uo, the voltage at the direct-current bus 61 and the negative electrode of the rechargeable battery B is U2, the voltage at a node formed by connecting the inductor L61 , the capacitor C61 and the cathode of the diode D61 is UBI , the voltage at a node formed by connecting the capacitor C61 , the emitter of the insulated gate bipolar transistor T62 and the inductor L63 is UAI , inductance values of the inductor L61 and the inductor L63 are respectively Li and l_3, the current in the inductor L61 and the inductor L63 are respectively iu and ii_3, a period of the pulse-width modulation signal is T, a duty cycle of the pulse-width modulation signal is d, and an on time and an off time of the insulated gate bipolar transistor T62 in one pulse-width modulation signal period are respectively Ton and Toff. One period of the pulse-width modulation signal is used as an example for description.
[0111] When the insulated gate bipolar transistor T62 is turned on, the following equations are satisfied:
Figure imgf000037_0001
Figure imgf000038_0001
[0112] When the insulated gate bipolar transistor T62 is turned off, the following equations are satisfied:
Figure imgf000038_0002
[0113] The average voltage of the inductor L63 in one switching period is 0, and thus:
Figure imgf000038_0003
Figure imgf000039_0001
[0114] Thus, Udc/Uo=d/(1 -d). When the duty cycle d is less than 0.5, buck discharging of the rechargeable battery B is achieved. When the duty cycle d is greater than 0.5, boost discharging of the rechargeable battery B is achieved.
[0115] The bi-directional DC-DC converter 6 of the present invention can controllably transmit electric energy in the capacitor between the positive and negative direct-current buses to the rechargeable battery B, and transmit electric energy in the rechargeable battery B to the capacitor between the positive and negative direct-current buses, thereby achieving bi-directional energy transmission.
[0116] FIG. 33 is a circuit diagram of a bi-directional DC-DC converter according to a fifth embodiment of the present invention. As shown in FIG. 33, the bi-directional DC-DC converter 7 differs from the bi-directional DC-DC converter 6 in FIG. 27 in that the bi-directional DC-DC converter 7 further includes an inductor L72, a capacitor C72, and an insulated gate bipolar transistor T73 having an anti-parallel diode D73. The inductor L72 is connected to an anode of a diode D71 and an emitter of an insulated gate bipolar transistor T71 , the capacitor C72 is connected between the anode of the diode D71 and an inductor L73, and a collector of the insulated gate bipolar transistor T73 (namely, a cathode of the diode D73) is collected to a node formed by connecting the capacitor C72 and the inductor L73.
[0117] Since the bi-directional DC-DC converter 7 has completely the same topology structure as that of the DC-DC converter 5, the operating principles thereof are not described herein again. Thus, the bi-directional DC-DC converter 7 can also be used in uninterrupted power supplies connected in parallel.
[0118] In other embodiments of the present invention, a switching tube such as a metal-oxide-semiconductor field effect transistor (MOSFET) is used in place of the insulated gate bipolar transistor in the aforementioned embodiment.
[0119] The present invention further provides an uninterrupted power supply, which includes the DC-DC converter or bi-directional DC-DC converter in the aforementioned embodiment, a power factor correction circuit (PFC) and an inverter, where the DC-DC converter or the bi-directional DC-DC converter is connected between positive and negative direct-current buses and a rechargeable battery, an input terminal of the PFC is connected to an alternating-current power supply (for example, a mains supply), an output terminal of the PFC is connected to the positive and negative direct-current buses, an input terminal of the inverter is connected to the positive and negative direct-current buses, and an output terminal of the inverter is used for providing an alternating current to a load.
[0120] Although the present invention has been described through preferred embodiments, the present invention is not limited to the embodiments described herein, but includes various changes and variations made without departing from the scope of the present invention.

Claims

Claims
1 . A DC-DC converter, comprising:
a first inductor, a first switching tube, and a second inductor connected in sequence;
a first diode, a third inductor, and a second diode connected in sequence;
a first capacitor, connected between an anode of the second diode and a node formed by connecting one terminal of the first switching tube and the first inductor; and
a second capacitor, connected between a cathode of the first diode and a node formed by connecting the other terminal of the first switching tube and the second inductor.
2. The DC-DC converter according to claim 1 , wherein when the first switching tube is turned on, the first inductor, the first switching tube, and the second inductor form a first current path, and the first capacitor, the first switching tube, the second capacitor, and the third inductor form a second current path; and when the first switching tube is turned off, the first diode, the third inductor, and the second diode form a third current path.
3. The DC-DC converter according to claim 2, wherein the first switching tube is a first insulated gate bipolar transistor, a collector of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the first inductor and the first capacitor, and an emitter of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the second inductor and the second capacitor, wherein the other terminal of the first inductor and the other terminal of the second inductor are respectively used for connecting to a positive electrode and a negative electrode of a first direct-current power supply device, and a cathode of the second diode and an anode of the first diode are respectively used for connecting to a positive electrode and a negative electrode of a second direct- current power supply device.
4. The DC-DC converter according to any one of claims 1 to 3, wherein the DC-DC converter further comprises:
a diode connected in anti-parallel to the first switching tube;
a second switching tube connected in anti-parallel to the first diode; and a third switching tube connected in anti-parallel to the second diode.
5. The DC-DC converter according to any one of claims 1 to 3, further comprising a control device for providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off.
6. The DC-DC converter according to claim 4, further comprising a control device for
controlling both the second switching tube and the third switching tube to turn off, and providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off; or
controlling the first switching tube to turn off, and providing the same pulse-width modulation signal to the second switching tube and the third switching tube, so that the second switching tube is alternately turned on and off and the third switching tube is alternately turned on and off.
7. A DC-DC converter, comprising:
a first switching tube, a first inductor, and a second switching tube connected in sequence;
a second inductor, a first diode, and a third inductor connected in sequence;
a first capacitor, connected between a cathode of the first diode and one terminal of the first inductor; and a second capacitor, connected between an anode of the first diode and the other terminal of the first inductor.
8. The DC-DC converter according to claim 7, wherein when both the first switching tube and the second switching tube are turned on, the first switching tube, the first inductor, and the second switching tube form a first current path; and when both the first switching tube and the second switching tube are turned off, the second inductor, the first diode, and the third inductor form a second current path, and the first capacitor, the first inductor, the second capacitor, and the first diode form a third current path.
9. The DC-DC converter according to claim 8, wherein
the first switching tube is a first insulated gate bipolar transistor, and an emitter of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the first inductor and the first capacitor; and
the second switching tube is a second insulated gate bipolar transistor, and a collector of the second insulated gate bipolar transistor is connected to a node formed by connecting the other terminal of the first inductor and the second capacitor, wherein
a collector of the first insulated gate bipolar transistor and an emitter of the second insulated gate bipolar transistor are respectively used for connecting to a positive electrode and a negative electrode of a first direct- current power supply device, and the third inductor and the second inductor are respectively used for connecting to a positive electrode and a negative electrode of a second direct-current power supply device.
10. The DC-DC converter according to any one of claims 7 to 9, wherein the DC-DC converter further comprises:
a third switching tube connected in anti-parallel to the first diode;
a second diode connected in anti-parallel to the first switching tube; and a third diode connected in anti-parallel to the second switching tube.
11 . The DC-DC converter according to any one of claims 7 to 9, further comprising a control device for providing the same pulse-width modulation signal to the first switching tube and the second switching tube, so that the first switching tube is alternately turned on and off and the second switching tube is alternately turned on and off.
12. The DC-DC converter according to claim 10, further comprising a control device for
controlling the third switching tube to turn off, and providing the same pulse-width modulation signal to the first switching tube and the second switching tube, so that the first switching tube is alternately turned on and off and the second switching tube is alternately turned on and off; or
controlling both the first switching tube and the second switching tube to turn off, and providing a pulse-width modulation signal to the third switching tube so that the third switching tube is alternately turned on and off.
13. A bi-directional DC-DC converter, comprising:
a first inductor and a first switching tube that are connected;
a first diode connected in anti-parallel to the first switching tube;
a second inductor and a second diode that are connected;
a second switching tube connected in anti-parallel to the second diode; and
a first capacitor, wherein one terminal of the first capacitor is connected to a cathode of the first diode, and the other terminal of the first capacitor is connected to a node formed by connecting an anode of the second diode and one terminal of the second inductor, wherein
an anode of the first diode is electrically connected to the other terminal of the second inductor.
14. The bi-directional DC-DC converter according to claim 13, wherein the first switching tube is a first insulated gate bipolar transistor, a collector of the first insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the first inductor and the first capacitor, and an emitter of the first insulated gate bipolar transistor and the other terminal of the first inductor are respectively used for connecting to a negative electrode and a positive electrode of a first direct-current power supply device; and
the second switching tube is a second insulated gate bipolar transistor, an emitter of the second insulated gate bipolar transistor is connected to a node formed by connecting one terminal of the second inductor and the first capacitor, and a collector of the second insulated gate bipolar transistor and the other terminal of the second inductor are respectively used for connecting to a positive electrode and a negative electrode of a second direct-current power supply device.
15. The bi-directional DC-DC converter according to claim 14, wherein the bi-directional DC-DC converter further comprises:
a third inductor, connected to the anode of the first diode;
a second capacitor, connected between the anode of the first diode and the other terminal of the second inductor;
a third diode, wherein a cathode of the third diode is connected to the other terminal of the second inductor, and wherein
a third switching tube connected in anti-parallel to the third diode;
the first inductor and the third inductor are respectively used for connecting to a positive electrode and a negative electrode of a first direct- current power supply device, and a cathode of the second diode and an anode of the third diode are respectively used for connecting to a positive electrode and a negative electrode of a second direct-current power supply device.
16. The bi-directional DC-DC converter according to claim 13 or 14, further comprising a control device for controlling the second switching tube to turn off, and providing a pulse- width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off; or
controlling the first switching tube to turn off, and providing a pulse-width modulation signal to the second switching tube so that the second switching tube is alternately turned on and off.
17. The bi-directional DC-DC converter according to claim 15, further comprising a control device for
controlling both the second switching tube and the third switching tube to turn off, and providing a pulse-width modulation signal to the first switching tube so that the first switching tube is alternately turned on and off; or
controlling the first switching tube to turn off, and providing the same pulse-width modulation signal to the second switching tube and the third switching tube, so that the second switching tube is alternately turned on and off and the third switching tube is alternately turned on and off.
18. An uninterrupted power supply, comprising:
the DC-DC converter according to any one of claims 1 to 12 or the bi directional DC-DC converter according to any one of claims 13 to 17, wherein the DC-DC converter or the bi-directional DC-DC converter is connected between positive and negative direct-current buses and a rechargeable battery;
a power factor correction circuit, wherein an input terminal of the power factor correction circuit is used for connecting to an alternating-current power supply, and an output terminal of the power factor correction circuit is connected to the positive and negative direct-current buses; and
an inverter, wherein an input terminal of the inverter is connected to the positive and negative direct-current buses, and an output terminal of the inverter is used for providing an alternating current.
PCT/EP2019/025413 2018-11-21 2019-11-21 Dc-dc converter, bi-directional dc-dc converter, and uninterrupted power supply including same WO2020104068A1 (en)

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