KR20220059218A - Battery charger with very side charge voltage range - Google Patents

Abstract

A battery charger with a very wide charging voltage range is disclosed. A DC-DC converter used in the battery charger comprises: a first transformer and a second transformer arranged in parallel with each other; a first sub-converter located on a primary side of the transformers; and a second sub-converter and a third sub-converter located on a secondary side of the transformers. Here, the second sub-converter and the third sub-converter are connected in parallel or series according to a charging voltage level of a battery, so that an output voltage of the DC-DC converter is changed.

Description

BATTERY CHARGER WITH VERY SIDE CHARGE VOLTAGE RANGE

The present invention relates to a battery charger having a very wide charging voltage range.

A conventional battery charger can only charge an electric vehicle having a charging voltage level of 250V to 500V. Accordingly, the battery charger cannot be applied to an electric vehicle having a charging voltage level of 500V to 1000V to be released in the future.

US 2019-0134374 A

The present invention is to provide a battery charger having a very wide charging voltage range.

In order to achieve the above object, a DC-DC converter used in a battery charger for charging a battery according to an embodiment of the present invention includes a first transformer and a second transformer arranged in parallel with each other; a first sub-converter located on the primary side of the transformers; and a second sub-converter and a third sub-converter positioned on the secondary side of the transformers. Here, the second sub-converter and the third sub-converter are connected in parallel or series according to the charging voltage level of the battery, so that the output voltage of the DC-DC converter is changed.

A DC-DC converter used in a battery charger for charging a battery according to another embodiment of the present invention includes a transformer; a primary side circuit located on the primary side of the transformer; and a secondary side circuit located on the secondary side of the transformer. Here, the primary circuit has at least one switch for switching an input voltage, the secondary circuit has a rectifier, and the secondary circuit varies according to the charging voltage level of the battery to output different output voltages, Although the output voltage is different, the switching frequency of the DC-DC converter is the same.

The battery charger according to the present invention can realize a very wide charging voltage range by selectively connecting the sub-converters of the DC-DC converter in series or parallel. In particular, the battery charger may have a high power conversion efficiency while realizing a wide charging voltage range.

1 is a block diagram illustrating a battery charger according to an embodiment of the present invention.
2 is a circuit diagram illustrating a DC-DC converter according to an embodiment of the present invention.
3 is a diagram illustrating a parallel connection structure of converters.
4 is a diagram illustrating a series connection structure of converters.
5 to 8 are diagrams illustrating main operation waveforms when a 250V to 500V battery is charged.
9 to 11 are diagrams illustrating main operation waveforms when charging a 500V to 1000V battery.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "consisting of" or "comprising" should not be construed as necessarily including all of the various components or various steps described in the specification, some of which components or some steps are It should be construed that it may not include, or may further include additional components or steps. In addition, terms such as "...unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software. .

The present invention relates to a battery charger used for charging an electric vehicle, and may have a circuit structure capable of high-efficiency operation while having a very wide battery charging voltage range.

According to one embodiment, the battery charger of this embodiment charges both an electric vehicle having a charging voltage level of 250V to 500V and an electric vehicle having a charging voltage level of 500V to 1000V through switching connecting the rectifiers in series/parallel. can That is, the battery charger may selectively output a charging voltage of 250V to 500V or 500V to 1000V according to the charging voltage level of the battery of the electric vehicle.

In particular, since the switching frequency of the DC-DC charger when charging in the voltage range of 250V to 500V and the switching frequency of the DC-DC charger when charging in the voltage range of 500V to 1000V are the same, the realization of high power conversion efficiency is It is possible.

Since electric vehicles having a charging voltage range of 500V to 1000V are scheduled to be released, a voltage range of 250V to 1000V may be implemented to charge existing electric vehicles and new electric vehicles, but in this case, the power conversion efficiency of the converter may be low. have no choice but to

Accordingly, the battery charger of the present invention operates to selectively implement a voltage range of 250V to 500V or a voltage range of 500V to 1000V, and thus the converter can have high power conversion efficiency. However, for such charging, the battery charger should detect the charging voltage level of the electric vehicle to be charged in advance.

Meanwhile, although the charging voltage range of the electric vehicle has been referred to as 250V to 500V or 500V to 1000V above, the range is not limited thereto.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating a battery charger according to an embodiment of the present invention, and FIG. 2 is a circuit diagram illustrating a DC-DC converter according to an embodiment of the present invention. 3 is a diagram illustrating a parallel connection structure of converters, and FIG. 4 is a diagram illustrating a series connection structure of converters. 5 to 8 are diagrams illustrating main operation waveforms when charging a 250V to 500V battery, and FIGS. 9 to 11 are diagrams illustrating main operation waveforms when charging a 500V to 1000V battery.

Referring to FIG. 1 , the battery charger 100 of this embodiment may be, for example, a fast charger for charging a battery of an electric vehicle, and may include a power factor correction unit 110 , a capacitor and a DC-DC converter 112 . can

The power factor correction unit 110 corrects and outputs the power factor of the power supplied from the system, and as a result, a predetermined DC voltage may be applied to the DC link.

The DC-DC converter 112 may convert a DC voltage applied to the DC link (hereinafter, referred to as “DC link voltage”) into a DC voltage of a different magnitude, and the converted DC voltage is charged to the battery of the electric vehicle. can be

According to an embodiment, the DC-DC converter 112 converts the DC link voltage to a first voltage range (eg 250V to 500V) or a second voltage range higher than the first voltage range (eg 500V). ~ 1000V). Specifically, when the DC-DC converter 112 detects the voltage range of the battery to be charged, the electric vehicle may be charged in the first voltage range or the second voltage range to match the sensed voltage range. .

Referring to the detailed structure of the DC-DC converter 112 with reference to FIG. 2 , the DC-DC converter 112 includes a first sub-converter 200, transformers 210 and 212, a second sub-converter 202, It may include a third sub-converter 204 , a resonance unit 206 , and switching units 230 and 232 .

The first sub-converter 200 is arranged on the primary side of the transformers 210 and 212, and provides the DC link voltage to the input side of the transformers 210 and 212 as a positive voltage and a negative voltage periodically. can

The first sub-converter 200 may include four semiconductor switches Q1, Q2, Q3, and Q4.

The first semiconductor switch Q1 and the third semiconductor switch Q3 may be arranged in parallel with each other while being connected to the DC link. Here, the first semiconductor switch Q1 and the third semiconductor switch Q3 may operate complementarily.

The second semiconductor switch Q2 may be connected in series to the first semiconductor switch Q1 , and the fourth semiconductor switch Q4 may be connected in series to the second semiconductor switch Q2 . As a result, the second semiconductor switch Q2 and the fourth semiconductor switch Q4 may be connected in parallel to each other. Here, the second semiconductor switch Q2 and the fourth semiconductor switch Q4 may operate complementarily.

Also, the first sub-converter 200 may additionally include input capacitors connected in parallel to the DC link. The capacitors may prevent the DC link voltage from being instantaneously supplied to the transformers 210 and 212 to achieve voltage stabilization.

One end of the primary side of the first transformer 210 is connected to the node n1 between the semiconductor switches Q1 and Q2 through an inductor and a capacitor, and the other end is connected to the node n1 between the semiconductor switches Q3 and Q4 through a capacitor. It may be connected to the node n2.

The secondary side of the first transformer 210 may be connected to the second sub-converter 202 .

According to an embodiment, the second sub-converter 202 may have a full-bridge structure formed of four diodes D1 , D2 , D3 and D4 as a rectifier. One end of the secondary side of the first transformer 210 is connected to the node n3 between the diodes D1 and D2 connected in series, and the other end is connected to the node (D3 and D4) between the diodes D3 and D4 connected in series. n4) can be connected.

The second transformer 212 is connected in parallel with the first transformer 210 and may have the same turns ratio as that of the first transformer 210 or may have a different turns ratio.

One end of the primary side of the second transformer 212 is connected to the node n1 between the semiconductor switches Q1 and Q2 through an inductor and a capacitor, and the other end is connected between the semiconductor switches Q3 and Q4 through a capacitor. may be connected to the node n2 of

The secondary side of the second transformer 212 may be connected to the third sub-converter 204 .

According to an embodiment, the third sub-converter 204 may have a full-bridge structure formed of four diodes D5, D6, D7, and D8 as a rectifier. One end of the secondary side of the second transformer 212 is connected to the node n5 between the diodes D5 and D6 connected in series, and the other end is connected to the node (D7 and D8) between the diodes D7 and D8 connected in series. n6) can be connected.

The resonator 206 may be formed of an inductor and a capacitor, and one end of the inductor may be connected to an output of the second sub-conductor 202 and an output of the third sub-conductor 204 . That is, the second sub-conductor 202 and the third sub-conductor 204 may share the resonator 206 .

According to an embodiment, the second sub-conductor 202 and the resonator 206 are electrically connected through the first switching unit 230 , and the third sub-conductor 204 and the resonator 206 are connected to the first They are electrically connected through the switching unit 230 , and the second sub-converter 202 and the third sub-converter 204 may be electrically connected through the second switching unit 232 . As a result, the connection between the second sub-conductor 202 , the third sub-conductor 204 and the resonator 206 may vary according to the switching operation of the switching units 230 and 232 .

Specifically, as shown in FIG. 3 , when the first switching unit 230 is turned on and the second switching unit 232 is turned off, the second sub-conductor 202 and the third sub-conductor 204 are The second sub-conductor 202 and the third sub-conductor 204 may be respectively connected to the resonator 206 while being connected in parallel. As a result, the output of the resonator 206 may output a voltage in the first voltage range, for example, 250V to 500V. Accordingly, it may be possible to charge the electric vehicle driven in the first voltage range, that is, having the first charging voltage level.

The advantage of the structure in which the second sub-conductor 202 and the third sub-conductor 204 are connected in parallel to each other is that when the low-voltage battery is charged with high power, a large charging current is generated between the second sub-conductor 202 and the third sub-conductor 204 ), the circuit can operate stably by dispersing current stress and heat. In this case, the charging current flowing through the second sub-conductor 202 and the third sub-conductor 204 may be the same.

On the other hand, as shown in FIG. 4 , when the first switching unit 230 is turned off and the second switching unit 232 is turned on, the second sub-conductor 202 and the third sub-conductor 204 are turned on. may be connected to each other in series, and the output of the second sub-conductor 202 may be connected to the resonator 206 . As a result, the output of the resonator 206 may output a voltage in the second voltage range, for example, 500V to 1000V. Accordingly, it may be possible to charge the electric vehicle driven in the second voltage range, that is, having the second charging voltage level.

An advantage of the structure in which the second sub-conductor 202 and the third sub-conductor 204 are connected in series is that high-voltage battery charging can be implemented with a low rated voltage diode, thereby reducing conduction loss.

In summary, the battery charger 100 of this embodiment connects the second sub-conductor 202 and the third sub-conductor 204 of the DC-DC converter 112 in series or parallel according to the battery charging voltage level to be charged. That is, a desired charging voltage can be realized by connecting two rectifiers in series or in parallel.

In particular, by forming the second sub-conductor 202 and the third sub-conductor 204 in the same structure, the DC-DC converter 112 can be operated with the same switching voltage regardless of the charging voltage level. That is, the switching frequency of the DC-DC converter 112 may be the same in both regions when charging in the first voltage range or charging in the second voltage range. This makes the power conversion efficiency when charging the first voltage range the same as the power conversion efficiency when charging the second voltage range, and at the same time has high power conversion efficiency (eg, 95% or more) and can charge the battery of the electric vehicle. there is.

In addition, the switching frequency variable width of the DC-DC converter 112 can be significantly reduced, which can reduce the size of the high-power transformer, thereby reducing the volume and weight of the battery charger 100 .

Operating waveform when charging battery 200V, 50A, operating waveform when charging battery 300V, 50A, operating waveform when charging battery 400V, 50A, operating waveform when charging battery 500V, 50A, operating waveform when charging battery 600V, 25A, charging 800V, 25A battery 5 to 11 show the operating waveform when charging the battery 400V and 25A.

From these operating waveforms, it can be confirmed that the battery charger 100 operates at the same switching frequency in both voltage regions regardless of the voltage level of 250-500V and the voltage level of 500-1000V. This means that it can easily make a very wide voltage range of 250-1000V while operating with high power conversion efficiency.

On the other hand, as long as the output voltage of the resonator 206 varies while the second sub-conductor 202 and the third sub-conductor 204 are connected in series or parallel, the circuit structure of the sub-conductors 200, 202, and 204 is It can be variously modified.

In addition, when viewed from another perspective, the DC-DC converter used in the battery charging unit of the present invention may include a transformer, a primary circuit located on the primary side of the transformer, and a secondary circuit located on the secondary side of the transformer. there is.

Here, the primary circuit may include at least one switch for switching an input voltage (eg, a DC link voltage), and the secondary circuit may have a rectifier and a resonance unit connected to the rectifier. In this case, the secondary-side circuit is varied according to the level of the charging voltage of the battery, so that the DC-DC converter may output different output voltages. In particular, even if the output voltage is different, the switching frequency of the DC-DC converter may be the same.

On the other hand, the components of the above-described embodiment can be easily grasped from a process point of view. That is, each component may be identified as each process. In addition, the process of the above-described embodiment can be easily understood from the point of view of the components of the apparatus.

The above-described embodiments of the present invention have been disclosed for purposes of illustration, and various modifications, changes, and additions will be possible within the spirit and scope of the present invention by those skilled in the art having ordinary knowledge of the present invention, and such modifications, changes and additions should be regarded as belonging to the following claims.

100: battery charger 110: power factor correction unit
112: DC-DC converter 200: first sub-conductor
202: second sub-conductor 204: third sub-conductor
210, 212: transformer 230: first switching unit
232: second switching unit

Claims (8)

A DC-DC converter used in a battery charger for charging a battery, the DC-DC converter comprising:
a first transformer and a second transformer arranged in parallel with each other;
a first sub-converter located on the primary side of the transformers; and
a second sub-converter and a third sub-converter positioned on the secondary side of the transformers,
The DC-DC converter of a battery charger, characterized in that the second sub-converter and the third sub-converter are connected in parallel or series according to the charging voltage level of the battery so that the output voltage of the DC-DC converter is changed. According to claim 1, wherein the second sub-converter is connected to the secondary side of the first transformer, the third sub-converter is connected to the secondary side of the second transformer, the second sub-conductor and the third sub-conductor A first switching unit is present between the conductors, and a second switching unit is present in each of the second sub-conductor and the third sub-conductor,
When the first switching unit is turned on and the second switching unit is turned off, the second sub-conductor and the third sub-conductor are connected in parallel so that the DC-DC converter provides an output voltage of a first voltage range to the battery and when the first switching unit is turned off and the second switching unit is turned on, the second sub-conductor and the third sub-conductor are connected in series so that the DC-DC converter operates in a second voltage range equal to or greater than the first voltage range A DC-DC converter of a battery charger, characterized in that it provides an output voltage of the battery to the battery. 3. The method of claim 2, wherein the second sub-converter and the third sub-converter each include a rectifier;
The first voltage range is 250V to 500V, the second voltage range is a DC-DC converter of a battery charger, characterized in that 500V to 1000V. 3. The method of claim 2,
The DC-DC converter of the battery charger further comprising a resonance part shared by the second sub-conductor and the third sub-conductor. 3. The method of claim 2, wherein the first sub-conductor is composed of four semiconductor switches that are switched,
One end of the primary side of the first transformer is connected to a node between two semiconductor switches connected in series and the other end is connected to a node between the other two semiconductor switches connected in series,
One end of the primary side of the second transformer is connected to a node between the two semiconductor switches and the other end is connected to a node between the other two semiconductor switches,
One end of the secondary side of the first transformer is connected to a node between two diodes connected in series of the second sub-conductors, and the other end is connected to a node between the other two diodes connected in series,
One end of the secondary side of the second transformer is connected to a node between two diodes connected in series of the third sub-conductors, and the other end is connected to a node between the other two diodes connected in series DC-DC converter in battery charger. The method of claim 1, wherein when the second sub-conductor and the third sub-conductor are connected in parallel, the DC-DC converter outputs a charging voltage of a first voltage range, and the second sub-conductor and the third sub-conductor When the conductors are connected in series, the DC-DC converter outputs a charging voltage of a second voltage range greater than or equal to the first voltage range,
The second sub-conductor and the third sub-conductor have the same circuit structure, and the switching frequency of the DC-DC converter when outputting the charging voltage of the first voltage range and the charging voltage of the second voltage range A DC-DC converter of a battery charger, characterized in that the switching frequency of the DC-DC converter at the time of output is the same. A DC-DC converter used in a battery charger for charging a battery, the DC-DC converter comprising:
Transformers;
a primary side circuit located on the primary side of the transformer; and
Including a secondary circuit located on the secondary side of the transformer,
the primary side circuit has at least one switch for switching the input voltage, the secondary side circuit has a rectifier;
DC-DC converter of a battery charger, characterized in that the secondary-side circuit is varied according to the level of the charging voltage of the battery to output different output voltages, and the switching frequency of the DC-DC converter is the same even if the output voltages are different . The DC-DC converter of a battery charger according to claim 7, wherein an output voltage of 250V to 500V or an output voltage of 500V to 1000V is output according to the charging voltage level, but an output voltage of 250V to 1000V is not output.

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