Reverse buck-boost integrated charger

Abstract

The present invention relates to a reverse buck-boost type integrated charger, and more particularly, to a reverse buck-boost type integrated charger applied to a vehicle in which a replaceable battery is applied. An object of the reverse buck-boost type integrated charger according to the present invention is to provide a reverse buck-boost type integrated charger which is relatively economical, can be implemented in a small volume, and has a simple structure in an electric vehicle in which a replaceable charging system is applied.

Description

TECHNICAL FIELD

[0001] The present application relates to a reverse buck-boost type integrated charger, and more particularly to a reverse buck-boost type integrated charger applied to a vehicle using a replaceable battery. BACKGROUND

[0002] Although the adoption of electric vehicles is accelerated and expanded for eco-friendly reasons, the charging infrastructure of electric vehicles does not keep up with the growth of electric vehicles. In particular, due to the characteristics of electric vehicles, electric vehicles require a relatively long charging time, and the expansion of the charging infrastructure is a more important element.

[0003] Meanwhile, in India and China, a replaceable battery system is being developed and expanded. The replaceable battery system refers to a system in which a battery installed inside an electric vehicle is replaceable and usable, and is used in two- and three-wheeled electric vehicles using a low-voltage battery such as 48 volts (V), rather than in electric vehicles using a relatively high-voltage battery.

[0004] The replaceable battery system can be used in both existing electric vehicle charging stations and existing battery replacement stations, and can increase the travel distance of an electric vehicle in a short time by replacing a replaceable battery.

[0005] However, implementing a replaceable battery system inside an electric vehicle requires additional circuits including a plurality of direct current to direct current (DC-DC) converters and a plurality of relay switches for linking between a replaceable battery and a charger installed in an existing electric vehicle, resulting in reduced economic efficiency, increased volume, and a relatively complex structure and driving algorithm.

[0006] [Related Art Documents]

[0007] [Patent Documents]

[0008] Korean Patent Laid-Open Gazette No. 10-2022-0161025 ("Apparatus for operation of buck-boost converter", published on December 6, 2022) SUMMARY

[0009] [Technical Problem]

[0010] An object of the present application is to provide a reverse buck-boost type integrated charger in an electric vehicle using a replaceable battery charging system, which can provide improved economic efficiency, be implemented with a reduced volume, and have a simplified structure.

[0011] [Technical Solution]

[0012] In one general aspect, there is provided a reverse buck-boost type integrated charger, including: a power conversion unit that receives alternating current from a power grid, converts the alternating current into direct current, and outputs the direct current; a rectification unit connected to output terminals of the power conversion unit and rectifying the output of the power conversion unit; a main battery connected to the rectification unit and receiving the direct current power; an inductor disposed between the rectification unit and the main battery; a replaceable battery having two terminals connected to opposite ends of the inductor, thereby enabling charging of the main battery; a bypass unit disposed between the inductor and the replaceable battery and determining electrical connection between the main battery and the replaceable battery; a converter switch disposed between the inductor and the replaceable battery; and a control unit that controls the power conversion unit, the bypass unit, and the converter switch to charge the main battery from the power grid or charge the main battery by using the replaceable battery.

[0013] The replaceable battery can include at least one replaceable battery, when the replaceable battery includes two or more replaceable batteries, the replaceable batteries are connected in parallel to each other, and the bypass unit can include relays, the number of the relays corresponding to the number of the replaceable batteries, and determining electrical connection between each of the replaceable batteries and the main battery.

[0014] The bypass unit can include relays disposed at both terminals of a single replaceable battery.

[0015] The bypass unit can include: a first relay having one terminal connected to one terminal of the inductor, and having the other terminal connected to one terminal of the replaceable battery; a second relay having one terminal connected between the first relay and one terminal of the replaceable battery, and having the other terminal connected to one terminal of the main battery; a third relay having one terminal connected to the other terminal of the replaceable battery, and having the other terminal connected to one terminal of the main battery; and a fourth relay having one terminal connected to the other terminal of the replaceable battery, and having the other terminal connected to the other terminal of the main battery; and the converter switch can be disposed between one terminal of the first relay and one terminal of the inductor.

[0016] The bypass unit can include a first relay having one terminal connected to one terminal of the inductor and having the other terminal connected to one terminal of the replaceable battery, a second relay having one terminal connected between the other terminal of the first relay and one terminal of the replaceable battery and having the other terminal connected to one terminal of the main battery, a third relay having one terminal connected to the other terminal of the inductor and having the other terminal connected to the other terminal of the replaceable battery, and a fourth relay having one terminal connected to the other terminal of the replaceable battery and having the other terminal connected to the other terminal of the main battery, and the converter switch can be disposed between one terminal of the third relay and the other terminal of the inductor.

[0017] The control unit can perform pulse width modulation (PWM) control on the switches included in the power conversion unit while controlling the converter switch to be turned off, thereby charging the main battery with the alternating current input from the power grid.

[0018] The control unit can perform pulse width modulation (PWM) control on the switches included in the power conversion unit while controlling the converter switch to be turned off, thereby charging the main battery with the alternating current input from the power grid.

[0019] The control unit can control the first relay and the third relay to be turned off and control the second relay and the fourth relay to be turned on, thereby connecting the replaceable battery in parallel to the main battery.

[0020] The charger can further include a sensing unit that senses a voltage from the power grid, wherein when the voltage from the power grid is sensed by the sensing unit during charging of the main battery with the replaceable battery, the control unit stops charging of the main battery with the replaceable battery and controls the power conversion unit, the bypass unit, and the converter switch to charge the main battery from the power grid.

[0021] [Advantageous Effects]

[0022] According to the reverse buck-boost type integrated charger in various embodiments of the present application, the reverse buck-boost type integrated charger can share a part of components included in the on-board charger and the buck-boost converter installed in the existing vehicle, thereby providing relatively improved economic efficiency, reduced size, and simplified algorithm.

[0023] In addition, according to the reverse buck-boost type integrated charger in various embodiments of the present application, the buck-boost converter can be implemented in the OBC, and the replaceable battery can be used together even when the output voltage of the replaceable battery is lower than the output voltage of the main battery. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 andFigure 2 A replaceable battery system installed in an existing vehicle is shown;

[0025] Figure 3 A replaceable battery system installed in an existing vehicle and collectively using a step-down converter is shown;

[0026] Figure 4 is a circuit diagram of a reverse step-down-boost type integrated charger according to a first embodiment of the present application;

[0027] Figure 5 shows an equivalent circuit when the reverse step-down-boost type integrated charger according to the first embodiment of the present application is operated in an alternating current (AC) charging mode;

[0028] Figure 6 shows an equivalent circuit when the reverse step-down-boost type integrated charger according to the first embodiment of the present application is operated in a replaceable battery charging mode;

[0029] Figure 7 is a circuit diagram of a reverse step-down-boost type integrated charger according to a second embodiment of the present application;

[0030] Figure 8 is a circuit diagram of another example of the reverse step-down-boost type integrated charger according to the second embodiment of the present application;

[0031] Figure 9 is a circuit diagram of a reverse step-down-boost type integrated charger according to a third embodiment of the present application;

[0032] Figure 10a and Figure 10b shows a secondary side of the reverse step-down-boost type integrated charger according to the third embodiment of the present application;

[0033] Figure 11 is a circuit diagram of a reverse step-down-boost type integrated charger according to a fourth embodiment of the present application; and

[0034] Figure 12 shows a flowchart when the reverse step-down-boost type integrated charger according to the present application is operated in an AC charging mode or a replaceable battery charging mode. DETAILED DESCRIPTION

[0035] The above-mentioned objects, features and advantages will become more apparent by the following embodiments taken in conjunction with the accompanying drawings. The following description of specific structures and functions is provided only as an example to describe embodiments based on the concept of the present application. Thus, embodiments of the present application can be implemented in various forms and the present application should not be construed as being limited to the embodiments described in the specification or claims. Embodiments of the present application can be variously modified and can have several forms, and thus specific embodiments are illustrated in the drawings and described in detail in the specification or claims. However, the present application is not limited to the specific embodiments and includes all modifications, equivalents, and substitutions included in the spirit and scope of the present application. Terms such as "first" or "second" can be used to describe various components, and the components are not limited by the terms. The terms are used only to distinguish one component from another component. For example, a "first" component can be referred to as a "second" component, and a "second" component can also be referred to as a "first" component without departing from the scope of the present application. It should be understood that when one component is referred to as being connected or coupled to another component, the one component can be directly connected or coupled to the other component, or can be connected or coupled to the other component with another component interposed therebetween. On the other hand, when one component is referred to as being directly connected or directly coupled to another component, the one component can be connected or coupled to the other component without another component interposed therebetween. Other expressions describing the relationship between components, such as "between" and "directly between", or "adjacent" and "directly adjacent", should be interpreted in the same manner. The terms used in the specification are used only to describe specific embodiments, and are not intended to limit the present application. Unless the context clearly indicates otherwise, a singular term can include its plural. It should be understood that the terms "include", "have", and the like used in the specification specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof stated in the specification and do not exclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Unless otherwise defined, all terms used herein (including technical or scientific terms) have the same meaning as understood by those skilled in the art to which the present application pertains. Terms commonly used and defined in a dictionary should be interpreted according to their meanings in the context of related art, and should not be interpreted as ideal or overly formal meanings unless otherwise clearly defined in the specification. Hereinafter, the present application will be described in detail by describing embodiments thereof with reference to the accompanying drawings. In the respective drawings, the same reference numerals denote the same elements.

[0036] Prior art will be described in more detail before describing the reverse buck-boost type integrated charger according to the present application.

[0037] Figure 1 and Figure 2 A replaceable battery system installed in an existing vehicle is shown.

[0038] As Figure 1 and Figure 2 shown, the replaceable battery system installed in the existing vehicle can include first to third step-down converters 11 to 13 corresponding to first to third replaceable batteries SB1 to SB3, respectively, and first to third bypass units 400 provided for the respective step-down converters. The replaceable battery system having such a structure can include the step-down converter and the bypass unit provided for each replaceable battery, which can cause an increase in volume of the battery system itself and a decrease in economic efficiency. In addition, the first to third replaceable batteries SB1 to SB3 are prevented from being simultaneously connected to the main battery 300, which indicates that the first to third replaceable batteries SB1 to SB3 are prevented from being simultaneously discharged. Generally, the replaceable battery can be replaced after being completely discharged, which indicates that the main battery 300 is also completely discharged, thus making the replacement of a specific replaceable battery difficult.

[0039] Figure 3 A replaceable battery system installed in an existing vehicle and commonly using a step-down converter is shown.

[0040] In Figure 3 the replaceable battery system shown, a single step-down converter 14 can be commonly used between the first to third replaceable batteries SB1 to SB3. However, as Figure 3 shown, only a single step-down converter 14 can be commonly used, and the number of bypass units is not reduced. Figure 3 The replaceable battery system shown has a structural difficulty in using the first to third replaceable batteries SB1 to SB3 by simultaneously connecting the first to third replaceable batteries SB1 to SB3 to the main battery 300, and when output voltages (charge capacities) of the first to third replaceable batteries SB1 to SB3 are different from each other, the open circuit voltage can be different, thus causing a cyclic charging phenomenon in which a small-capacity replaceable battery is charged by a large-capacity replaceable battery, thus causing an increase in internal loss of the battery and a decrease in battery life.

[0041] [First Embodiment]

[0042] Figure 4 is a circuit diagram of a reverse step-down-boost type integrated charger according to the first embodiment of the present application.

[0043] As Figure 4As shown, the reverse step-down-step-up type integrated charger according to the first embodiment of the present application can include a power conversion unit 100, a rectification unit 200, a main battery 300, an inductor L, first to third replaceable batteries SB1 to SB3, a bypass unit 400, a converter switch S5, and a control unit (not shown).

[0044] The power conversion unit 100 can receive alternating current from the power grid 10 to convert the alternating current into direct current, and output the direct current. As shown, Figure 4 As shown, the power conversion unit 100 can include a power factor correction unit 110, a link capacitor C, a switching unit 120, and a transformer 130.

[0045] The power factor correction unit 110 can improve a power factor of the alternating current received from the power grid 10 and output the improved power factor.

[0046] The link capacitor C can be connected to output terminals of the power factor correction unit 110 and store power. The switching unit 120 can include input terminals connected to the output terminals of the power factor correction unit 110, and include first to fourth switches S1 to S4 formed in a full-bridge form. In more detail, the first and second switches S1 and S2 can be connected to one switching branch, and the third and fourth switches S3 and S4 can be included in one switching branch. One output terminal of the power factor correction unit 110 can be connected to a node between the first and second switches S1 and S2, and the other output terminal of the power factor correction unit 110 can be connected to a node between the third and fourth switches S3 and S4. However, the present application does not limit the switching unit 120 to include the first to fourth switches S1 to S4 in the full-bridge form, and the switching unit 120 can further include a switch in a half-bridge form or various structures and additional electronic components.

[0047] The transformer 130 can be connected to output terminals of the switching unit 120, and transform direct current input to a primary side thereof and output the transformed direct current to a secondary side.

[0048] The rectifying unit 200 can be connected to the secondary side of the transformer 130 and include first to fourth diodes D1 to D4 formed in a full-bridge form. In more detail, the first and second diodes D1 and D2 can be connected in series to form one leg, and the third and fourth diodes D3 and D4 can be connected in series to form one leg. One output terminal of the secondary side of the transformer 130 can be connected to a node between the first and second diodes D1 and D2, and the other output terminal of the secondary side can be connected to a node between the third and fourth diodes D3 and D4. The rectifying unit 200 can be used to rectify power output through the transformer 130. The present application does not limit the form of the first to fourth diodes D1 to D4 included in the rectifying unit 200 to be formed in a full-bridge form, and a rectifying unit 200 including diodes in a half-bridge form or including other electronic components can also be implemented.

[0049] The main battery 300 can be connected in parallel to the rectifying unit 200. Referring to Figure 4 , the upper side of the main battery 300 indicates its positive terminal, and the lower side of the main battery 300 indicates its negative terminal. This configuration can be applied not only to the main battery 300 but also to each of the first to third replaceable batteries SB1 to SB3 to be described below, and the upper side of the battery indicates its positive terminal, and the lower side of the battery indicates its negative terminal. The diodes included in the rectifying unit 200 can be disposed to allow current to flow only from the lower side to the upper side.

[0050] The inductor L can be disposed between the lower terminal of the rectifying unit 200 and the negative terminal of the main battery 300.

[0051] The first to third replaceable batteries SB1 to SB3 can have two terminals connected to opposite ends of the inductor L. The first to third replaceable batteries SB1 to SB3 can be connected to each other to charge the main battery 300 when needed, and can be replaceable when discharged. Referring to Figure 4 , the upper side of each of the first to third replaceable batteries SB1 to SB3 indicates a positive terminal, and the lower side thereof indicates a negative terminal.

[0052] The bypass unit 400 can include first to third relays R1 to R3. Each of the first to third relays R1 to R3 can have one terminal connected to one terminal of the inductor L, and can have the other terminal connected to the positive terminal of each of the first to third replaceable batteries SB1 to SB3. The bypass unit 400 can electrically connect or disconnect the replaceable battery to the main battery 300 to charge the main battery 300 by using the replaceable battery.

[0053] A converter switch S5 can be provided between the other terminal of the inductor L and the negative terminal of each of the first to third replaceable batteries SB1 to SB3. In Figure 4 In this embodiment, the rectification unit 200 and the inductor L can form a part of an on-board charger (OBC) mounted in a vehicle, and also simultaneously operate as a step-down-step-up converter. That is, in this embodiment, the on-board charger and the step-down-step-up converter can share the rectification unit 200 and the inductor L. The converter switch S5 can be included in the step-down-step-up converter, and not shared with the on-board charger.

[0054] The control unit can control the power conversion unit 100, the bypass unit 400, and the converter switch S5 as described above to charge the main battery 300 by receiving alternating-current power from the power grid 10, or to charge the main battery 300 by using the first to third replaceable batteries SB1 to SB3. For this control, the control unit can be connected to each component in a wired or wireless manner to receive control signals and status signals, and can be implemented as an electronic component for generating and applying control signals or a device including the same.

[0055] Among the operation modes of the control unit, the mode in which the main battery 300 is charged using alternating current is referred to as an AC charging mode, and the mode in which the main battery 300 is charged using a replaceable battery is referred to as a replaceable battery charging mode.

[0056] Figure 5 An equivalent circuit is shown when the reverse step-down-step-up type integrated charger according to the present embodiment is operated in the AC charging mode.

[0057] Referring to Figure 5 The above-described AC charging mode is described. As Figure 5 As shown, when the reverse step-down-step-up type integrated charger according to the present embodiment is operated in the AC charging mode, the control unit can control the converter switch S5 to be turned off, perform pulse width modulation (PWM) control on the first to fourth switches S1 to S4 included in the switching unit 120, and charge the main battery 300 using the power conversion unit 100. By comparing Figure 4 With Figure 5 When the reverse step-down-step-up type integrated charger according to the present embodiment is operated in the AC charging mode, the first to third relays R1 to R3 included in the bypass unit 400 can be turned off to disconnect the electrical connection between the replaceable batteries and the main battery 300.

[0058] Figure 6 An equivalent circuit is shown when the reverse step-down-step-up type integrated charger according to the present embodiment is operated in the replaceable battery charging mode.

[0059] When the step-down-step-up integrated charger according to the present embodiment is operated in the replaceable battery charging mode, the control unit can control the first switch S1 to the fourth switch S4 included in the switching unit 120 to be turned off, and can perform PWM control on the converter switch S5. Figure 6 The illustrated operation embodiment describes an operation embodiment of charging the main battery 300 using the first replaceable battery SB1 among the first replaceable battery SB1 to the third replaceable battery SB3. To this end, the first relay R1 can be controlled to be turned on, and the second relay R2 and the third relay R3 can be controlled to be turned off. The description that the control unit performs PWM control on the converter switch S5 indicates that the period in which the converter switch S5 is turned on and the period in which the converter switch S5 is turned off are repeated. Figure 6 (a) of FIG. 1 shows the current flow when the converter switch S5 is turned on, and Figure 6 (b) of FIG. 1 shows the current flow when the converter switch S5 is turned off.

[0060] As shown in Figure 6 (a) of FIG. 1, when the converter switch S5 is controlled to be turned on, the electric power stored in the first replaceable battery SB1 can be stored in the inductor L. Subsequently, as shown in Figure 6 (b) of FIG. 1, when the converter switch S5 is controlled to be turned off, the current stored in the inductor L can flow to the main battery 300, thereby charging the main battery 300. The states shown in Figure 6 (a) of FIG. 1 and Figure 6 (b) of FIG. 1 can be repeated, thereby charging the main battery 300.

[0061] As described above, the reverse step-down-step-up integrated charger according to the present application can share the rectification unit 200 and the inductor L installed between the step-down-step-up converter and the on-board charger installed in the vehicle, thereby achieving improved economic efficiency, reduced size, and simplified algorithm complexity. In addition, the reverse step-down-step-up integrated charger according to the present application can be more simply implemented as a replaceable battery system because only the converter switch S5, the first replaceable battery SB1 to the third replaceable battery SB3, and the bypass unit 400 need to be installed on the secondary side of the existing on-board charger. Although not shown in Figure 4 or Figure 6 , an embodiment in which the inductor L, the first replaceable battery SB1 to the third replaceable battery SB3, and the converter switch S5 are installed on the upper side of the rectification unit 200 instead of the lower side thereof can also be implemented.

[0062] [Second Embodiment]

[0063] Figure 7is a circuit diagram of a reverse buck-boost type integrated charger according to a second embodiment of the present application.

[0064] As Figure 7 indicated, the reverse buck-boost type integrated charger according to the second embodiment of the present application differs from the reverse buck-boost type integrated charger according to the first embodiment of the present application described above in that the bypass unit 400 includes relays respectively provided at the positive and negative terminals of the single replaceable battery. When only the relays respectively provided at the positive and negative terminals of the first replaceable battery SB1 among the first to third replaceable batteries SB1 to SB3 are described, the relays respectively provided at the positive and negative terminals of the first replaceable battery SB1 can be referred to as a first-first relay R11 and a first-second relay R12; the relays respectively provided at the positive and negative terminals of the second replaceable battery SB2 can be referred to as a second-first relay R21 and a second-second relay R22; and the relays respectively provided at the positive and negative terminals of the third replaceable battery SB3 can be referred to as a third-first relay R31 and a third-second relay R32. In the charger according to the present embodiment having the above-described configuration, when at least one of the first to third replaceable batteries SB1 to SB3 is replaced, the corresponding nth-first relay and the corresponding nth-second relay (n is any one of 1 to 3) can be turned off, thereby enabling the first to third replaceable batteries SB1 to SB3 to be replaced more safely.

[0065] Figure 8 is a circuit diagram of another example of a reverse buck-boost type integrated charger according to the second embodiment of the present application.

[0066] In Figure 8 the reverse buck-boost type integrated charger, the arrangement directions of the first to third replaceable batteries SB1 to SB3 are opposite to those in the reverse buck-boost type integrated charger Figure 7 . That is, the first to third replaceable batteries SB1 to SB3 can be connected to the positive terminal of the main battery 300. The first-first relay R11 and the first-second relay R12 included in the bypass unit 400 can be provided at the two terminals of the first replaceable battery SB1, respectively; the second-first relay R21 and the second-second relay R22 can be provided at the two terminals of the second replaceable battery SB2, respectively; and the third-first relay R31 and the third-second relay R32 can be provided at the two terminals of the third replaceable battery SB3, respectively. Figure 8 The embodiment shown in FIG. 18 can also allow the first to third replaceable batteries SB1 to SB3 to be more safely separated from the main battery 300, similarly to the embodiment shown in FIG. 17.Figure 7 The embodiment shown in FIG. 1 is an example of the reverse step-down- step-up type integrated charger according to the first embodiment of the present application. However, referring to FIG. 2, the first-second relay R12, the second-second relay R22, and the third-second relay R32 provided on the lower side are not essential for the operation of the reverse step-down-step-up type integrated charger according to the present embodiment, and can be components added for safety. Figure 8

[0067] [Third Embodiment and Fourth Embodiment]

[0068] Figure 9 is a circuit diagram of a reverse step-down-step-up type integrated charger according to a third embodiment of the present application.

[0069] As shown in FIG. 1, the reverse step-down-step-up type integrated charger according to the third embodiment of the present application differs from the reverse step-down-step-up type integrated charger according to the first embodiment of the present application described above in that the bypass unit 400 includes a larger number of relays. Figure 9

[0070] In more detail, in this embodiment, the inductor L can be provided between the lower side of the rectifier 200 and the positive terminal of the main battery 300. The bypass unit 400 can include four relays for a single replaceable battery. In the case where only the first replaceable battery SB1 is described, the bypass unit 400 can include a first relay R1 to a fourth relay R4 for the first replaceable battery SB1.

[0071] The first relay R1 can have one terminal connected to the inductor L and one terminal connected to the negative terminal of the main battery 300, and can have the other terminal connected to the positive terminal of the first replaceable battery SB1.

[0072] The second relay R2 can have one terminal connected between the other terminal of the first relay R1 and the positive terminal of the first replaceable battery SB1, and can have the other terminal connected to the positive terminal of the main battery 300.

[0073] The third relay R3 can have one terminal connected to the negative terminal of the first replaceable battery SB1, and can have the other terminal connected to the other terminal of the inductor L. However, as shown in FIG. 1, the converter switch S5 can also be provided between the other terminal of the third relay R3 and the other terminal of the inductor L. Figure 9

[0074] The fourth relay R4 can have one terminal connected to the negative terminal of the first replaceable battery SB1, and can have the other terminal connected to the negative terminal of the main battery 300.

[0075] The first relay R1 to the fourth relay R4 described above can be controlled by the control unit.​​​

[0076] Figure 10a and Figure 10b The secondary side of the reverse buck-boost type integrated charger according to the third embodiment of the present application is shown, and only the first replaceable battery SB1 among the first to third replaceable batteries SB1 to SB3 is shown. In Figure 10a and Figure 10b between, Figure 10a The bypass mode, that is, the case where the first replaceable battery SB1 is connected in parallel to the main battery 300 is shown, and Figure 10b The replaceable battery charging mode in which the first replaceable battery SB1 described above is used to charge the main battery 300 is shown.

[0077] As Figure 10a shown, when the control unit intends to use the main battery 300 and the first replaceable battery SB1 together by connecting these batteries in parallel, the control unit can control the first relay R1 and the third relay R3 to be off, and control the second relay R2 and the fourth relay R4 to be on. In this case, the positive terminal of the first replaceable battery SB1 and the positive terminal of the main battery 300 can be connected to each other, and the negative terminal of the first replaceable battery SB1 and the negative terminal of the main battery 300 can be connected to each other. That is, the first replaceable battery SB1 and the main battery 300 can be connected in parallel to each other.

[0078] On the other hand, as Figure 10b shown, when the control unit intends to use the charger according to the present embodiment in the replaceable battery charging mode, the control unit can control the first relay R1 and the third relay R3 to be on, and can control the second relay R2 and the fourth relay R4 to be off. In this case, the control unit can perform PWM control on the converter switch S5.

[0079] Figure 11 is a circuit diagram of a reverse buck-boost type integrated charger according to a fourth embodiment of the present application.

[0080] As Figure 11 shown, the reverse buck-boost type integrated charger according to the fourth embodiment of the present application is similar to the charger according to the third embodiment of the present application described above in that the bypass unit 400 also includes four relays for a single replaceable battery. However, the charger according to the present embodiment is different from the charger according to the third embodiment in that the inductor L, the converter switch S5, and the first to third replaceable batteries SB1 to SB3 are coupled to the upper side of the rectifier 200. In this case, the positions of the first to fourth relays R1 to R4 included in the bypass unit 400 can be partially different.

[0081] In more detail, in this embodiment, the inductor L can be provided between the upper side of the rectifier 200 and the positive terminal of the main battery 300. The bypass unit 400 can include four relays for a single replaceable battery.

[0082] In this embodiment, the first relay Rl can have one terminal connected to one terminal of the inductor L, and can have the other terminal connected to the positive terminal of the first replaceable battery SB 1. However, the converter switch S5 can be provided between one terminal of the first relay Rl and one terminal of the inductor L. That is, referring to Figure 11 , the upper terminal of the converter switch S5 can be connected to one terminal of the first relay Rl, and the lower terminal of the converter switch S5 can be connected to one terminal of the inductor L.

[0083] The second relay R2 can have one terminal connected between the first relay Rl and the positive terminal of the first replaceable battery SB 1, and can have the other terminal connected to the positive terminal of the main battery 300 and the other terminal of the inductor L.

[0084] The third relay R3 can have one terminal connected to the negative terminal of the first replaceable battery SB 1, and can have the other terminal connected to the positive terminal of the main battery 300.

[0085] The fourth relay R4 can have one terminal connected to the negative terminal of the first replaceable battery SB 1, and can have the other terminal connected to the negative terminal of the main battery 300.

[0086] The above-described first to fourth relays Rl to R4 can be controlled by the control unit.

[0087] As described above with reference to FIG. 10, when the charger according to the present embodiment is operated in the bypass mode, that is, when the control unit intends to connect the first replaceable battery SB 1 in parallel to the main battery 300 and use these batteries, the control unit can control the first relay Rl and the third relay R3 to be off, and can control the second relay R2 and the fourth relay R4 to be on. On the other hand, when the charger according to the present embodiment is operated in the replaceable battery charging mode, the control unit can control the first relay Rl and the third relay R3 to be on, and can control the second relay R2 and the fourth relay R4 to be off.

[0088] Figure 12 A flowchart is shown when the reverse buck-boost type integrated charger according to the present application is operated in the AC charging mode or the replaceable battery charging mode.

[0089] As described above with reference to FIG. 10, when the charger according to the present embodiment is operated in the bypass mode, that is, when the control unit intends to connect the first replaceable battery SB 1 in parallel to the main battery 300 and use these batteries, the control unit can control the first relay Rl and the third relay R3 to be off, and can control the second relay R2 and the fourth relay R4 to be on. On the other hand, when the charger according to the present embodiment is operated in the replaceable battery charging mode, the control unit can control the first relay Rl and the third relay R3 to be on, and can control the second relay R2 and the fourth relay R4 to be off. Figure 12As shown, when the reverse buck-boost type integrated charger according to the present application is initially executed, the control unit can initialize the device and control all switches and relays to be off. Subsequently, the control unit can determine whether AC power is input from the power grid and determine whether to operate in an AC charging mode. The present application can include a separate sensing unit for sensing AC power input into the power grid, and the sensing unit can be implemented as a voltage sensor. When AC power is input from the power grid, the control unit charges the main battery 300 by controlling only the first to fourth switches S1 to S4.

[0090] When AC power is not input from the power grid, the control unit can operate the charger according to the present embodiment in a replaceable battery charging mode. Subsequently, the control unit can check whether each of the first to third replaceable batteries SB1 to SB3 is in a dischargeable state. The items that the control unit checks whether each of the first to third replaceable batteries SB1 to SB3 is in a dischargeable state can include a state of charge (SOC) level, an output voltage, and a temperature of each replaceable battery. When any one of the replaceable batteries is determined to be dischargeable among all the replaceable batteries, the control unit can turn on a relay corresponding to the replaceable battery, perform PWM control on the converter switch S5, and perform a boost operation. When the discharge of the corresponding replaceable battery is completed, the control unit can control the converter switch S5 to be off, and can control the relay corresponding to the replaceable battery to be off. Subsequently, the control unit can also perform the same operation on another replaceable battery.

[0091] Although embodiments of the present application are illustrated and described above, the embodiments of the present application are not intended to limit the spirit of the present application, but to describe the spirit of the present application. Therefore, the spirit of the present application includes not only each disclosed embodiment, but also combinations of the disclosed embodiments. Furthermore, the scope of the present application is not limited to the embodiments. In addition, those skilled in the art to which the present application pertains can make various changes and modifications to the present application without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are to be construed as equivalent and falling within the scope of the present application.

[0092] [Description of reference numerals]

[0093] 10: power grid

[0094] 11 to 13: first to third step-down converters

[0095] 14: step-down converter

[0096] 100: power conversion unit

[0097] 110: power factor correction unit

[0098] 120: switching unit

[0099] 130: transformer

[0100] 200: rectifying unit

[0101] 300: main battery

[0102] 400: bypass unit

[0103] C: link capacitor

[0104] D1 to D4: first to fourth diodes

[0105] L: inductor

[0106] R1 to R4: first to fourth relays

[0107] R11: first-first relay

[0108] R12: first-second relay

[0109] R21: second-first relay

[0110] R22: second-second relay

[0111] R31: third-first relay

[0112] R32: third-second relay

[0113] S1 to S4: first to fourth switches

[0114] S5: converter switch

[0115] SB1 to SB3: first to third replaceable batteries

Claims

1. A reverse buck-boost type integrated charger, comprising: a power conversion unit that receives alternating current from a power grid, converts the alternating current into direct current, and outputs the direct current; a rectification unit that is connected to output terminals of the power conversion unit and rectifies the output of the power conversion unit; a main battery that is connected to the rectification unit and receives direct current power; an inductor that is provided between the rectification unit and the main battery; a replaceable battery that has two terminals connected to opposite ends of the inductor, thereby enabling charging of the main battery so that the main battery can be charged; a bypass unit that is provided between the inductor and the replaceable battery and determines electrical connection between the main battery and the replaceable battery; a converter switch that is provided between the inductor and the replaceable battery; and a control unit that controls the power conversion unit, the bypass unit, and the converter switch to charge the main battery from the power grid or charge the main battery by using the replaceable battery. The replaceable battery includes at least one replaceable battery, 2. The charger of claim 1, wherein, when the replaceable battery includes two or more replaceable batteries, the replaceable batteries are connected in parallel to each other, and the bypass unit includes relays whose number corresponds to the number of the replaceable batteries and determines electrical connection between each replaceable battery and the main battery. The bypass unit includes relays provided at both terminals of a single replaceable battery.

3. The charger of claim 1, wherein, The bypass unit includes:

4. The charger of claim 1, wherein, a first relay whose one terminal is connected to one terminal of the inductor and whose other terminal is connected to one terminal of the replaceable battery, a second relay whose one terminal is connected between the first relay and one terminal of the replaceable battery and whose other terminal is connected to one terminal of the main battery, a third relay whose one terminal has the other terminal of the replaceable battery connected thereto and whose other terminal is connected to one terminal of the main battery, and a fourth relay whose one terminal is connected to the other terminal of the replaceable battery and whose other terminal is connected to the other terminal of the main battery, and the converter switch is provided between one terminal of the first relay and one terminal of the inductor. The bypass unit includes:

5. The charger of claim 1, wherein, a first relay whose one terminal is connected to one terminal of the inductor and whose other terminal is connected to one terminal of the replaceable battery, a second relay whose one terminal is connected between the other terminal of the first relay and one terminal of the replaceable battery and whose other terminal is connected to one terminal of the main battery, a third relay whose one terminal is connected to the other terminal of the inductor and whose other terminal is connected to the other terminal of the replaceable battery, and a fourth relay whose one terminal is connected to the other terminal of the replaceable battery and whose other terminal is connected to the other terminal of the main battery, and the converter switch is provided between one terminal of the third relay and the other terminal of the inductor. ​ 6. The charger of claim 1, wherein, The control unit performs pulse width modulation (PWM) control on the switches included in the power conversion unit while controlling the converter switches to be turned off, thereby charging the main battery with alternating current input from the power grid.

7. The charger of claim 1, wherein, The control unit performs pulse width modulation (PWM) control on the switches included in the power conversion unit while controlling the converter switches to be turned off, thereby charging the main battery with alternating current input from the power grid.

8. The charger of any one of claims 4 and 5, wherein, The control unit controls the first and third relays to be turned off and the second and fourth relays to be turned on, thereby connecting the replaceable battery in parallel to the main battery.

9. The charger according to claim 1, further comprising: a sensing unit that senses a voltage from the power grid; wherein when a voltage from the power grid is sensed by the sensing unit during charging of the main battery by the replaceable battery, the control unit stops charging of the main battery by the replaceable battery and controls the power conversion unit, the bypass unit, and the converter switches to charge the main battery from the power grid.

Images