Patent ID: 12257925

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same or similar elements are designated by the same reference numerals regardless of the numerals in the drawings and redundant description thereof will be omitted. The suffixes “module” and “unit” of elements herein are used for convenience of description and thus can be used interchangeably and do not have any distinguishable meanings or functions. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the embodiments of the present invention. In addition, the embodiments of the present invention will be more clearly understood from the accompanying drawings and should not be limited by the accompanying drawings, and it is to be appreciated that all changes, equivalents, and substitutes that do not depart from the spirit and technical scope of the present invention are encompassed in the present invention.

It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

In the case where an element is “connected” or “linked” to another element, it should be understood that the element may be directly connected or linked to the other element, or another element may be present therebetween. Conversely, in the case where an element is “directly connected” or “directly linked” to another element, it should be understood that no other element is present therebetween.

Unless clearly used otherwise, singular expressions include a plural meaning.

In this specification, the term “comprising,” “including,” or the like, is intended to express the existence of the characteristic, the numeral, the step, the operation, the element, the part, or the combination thereof, and does not exclude another characteristic, numeral, step, operation, element, part, or any combination thereof, or any addition thereto.

Some embodiments of the present invention provide a converter capable of managing a state of charge of each auxiliary battery and effectively controlling charging current. Embodiments may also provide a converter capable of enabling batteries to be effectively used.

FIG.1shows a vehicle100to which a power conversion system according to an exemplary embodiment of the present invention is applied.

Referring toFIG.1, the vehicle100includes a main battery no and an auxiliary battery130. The vehicle100uses energy stored in the main battery no as a power source for driving a motor. When the stored energy of the main battery no is discharged, the vehicle100receives power from the auxiliary battery130, thereby recharging the main battery no.

FIG.2shows a power conversion system according to an exemplary embodiment of the present invention.

Referring toFIG.2, the power conversion system according to this embodiment includes an AC power source210, an on-board charger (OBC)220, a main battery230, an auxiliary battery240, and a power converter250.

AC power from the AC power source210is applied to the on-board charger220in order to recharge the main battery230. In this case, the AC power source210may be a power source installed in external charging equipment.

The on-board charger220converts an AC voltage from the AC power source210into a DC voltage capable of recharging the main battery230, and then supplies the DC voltage to the main battery230. The on-board charger220includes a power factor compensation circuit221, a link capacitor C21, an LLC circuit225, a transformer T21, and a rectifier circuit229. In this case, the power factor compensation circuit221, the link capacitor C21, the LLC circuit225, the transformer T21, and the rectifier circuit229may be implemented in various topologies in the present technical field.

The main battery230is recharged with power and supplies the charged power to a motor (not shown), thereby supplying rotation force to a wheel of a vehicle. In this case, the main battery230may be recharged by DC charging power supplied from the on-board charger220or the auxiliary battery240. The main battery230may be a low-voltage output type battery and, may be, for example, a 48V standard battery. In this case, although the main battery230is of a 48V standard, the main battery230may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof.

The auxiliary battery240is constituted by a plurality of auxiliary batteries241,242, and243, and assists a function of an energy source for recharging the main battery230or driving the motor of the main battery230. In this case, the auxiliary battery240may be a low-voltage output type battery and, may be, for example, a 48V standard battery. Although the auxiliary battery240is of a 48V standard, the auxiliary battery240may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof, similarly to the main battery230.

In this case, the auxiliary battery240may be provided in the form of a swappable battery.

The power converter250converts a voltage of the auxiliary battery240into a voltage having a level suitable for charging the main battery230. In this case, since both the auxiliary battery240and the main battery230have DC voltages, the power converter250functions as a DC-DC converter. In this case, the power converter250includes a plurality of power converters255,260, and265equal in number to the plurality of auxiliary batteries241,242, and243such that the power converters255,260, and265are connected to the auxiliary batteries241,242, and243, respectively. A concrete structure of the power converter250will be described in detail with reference to an auxiliary battery power conversion device ofFIGS.3and4which will be described later.

FIG.3shows an auxiliary battery power conversion device according to an exemplary embodiment of the present invention.

Referring toFIG.3, the power conversion device according to this embodiment includes a main battery230, an auxiliary battery240, and a power converter250. In this case, the auxiliary battery power conversion device ofFIG.3may constitute a part of the power conversion system ofFIG.2.

The main battery230is recharged with power, and supplies the charged power to a motor (not shown), thereby supplying rotation force to a wheel of a vehicle. In this case, the main battery230may be recharged by DC charging power supplied from the auxiliary battery240. The main battery230may be a low-voltage output type battery and, may be, for example, a 48V standard battery. In this case, although the main battery230is of a 48V standard, the main battery230may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof.

The auxiliary battery240assists a function of an energy source for recharging the main battery230or driving the motor of the main battery230.

The auxiliary battery240may include a plurality of auxiliary batteries241,242, and243. Although the auxiliary battery240is shown as being configured through inclusion of first to third auxiliary batteries241,242, and243in the embodiment ofFIG.3, this is only illustrative, and the auxiliary battery240may include various numbers of auxiliary batteries.

In this case, the auxiliary battery240may be a low-voltage output type battery and, may be, for example, a 48V standard battery. Although the auxiliary battery240is of a 48V standard, the auxiliary battery240may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof, similarly to the main battery230.

In this case, the auxiliary battery240may be provided in the form of a swappable battery.

The power converter250converts a voltage of the auxiliary battery240into a voltage having a level suitable for charging the main battery230. In this case, the power converter250may be configured to be equal in number to the plurality of auxiliary batteries241,242, and243. Although the power converter250is shown as being configured through inclusion of first to third power converters255,260, and265in the embodiment ofFIG.3, this is only illustrative, and the power converter250may include various numbers of power converters.

Referring toFIG.3, the first to third power converters255,260, and265may include respective bypass circuits256,261, and266and respective buck converters257,262, and267. Each of the first to third auxiliary batteries241,242, and243is connected to a corresponding one of the first to third bypass circuits256,261, and266and a corresponding one of the first to third buck converters257,262, and267.

In this case, each of the first to third auxiliary batteries241,242, and243is connected to the corresponding one of the first to third bypass circuits256,261, and266and the corresponding one of the first to third buck converters257,262, and267, and a power supply path thereof connected to the main battery230is switched by the corresponding one of the first to third bypass circuits256,261, and266and the corresponding one of the first to third buck converters257,262, and267.

When voltages of the auxiliary batteries241,242, and243respectively connected to the buck converters257,262, and267are higher than the voltage of the main battery230, the buck converters257,262, and267drop the voltages of the auxiliary batteries241,242, and243, respectively, and supply the dropped voltages to the main battery230. In this case, the voltages supplied to the main battery230through the buck converters257,262, and267may be used to recharge the main battery230.

Meanwhile, a circuit of each of the bypass circuits256,261, and266operates when the voltage of a corresponding one of the auxiliary batteries241,242, and243connected thereto is equal to the voltage of the main battery230, thereby electrically connecting the corresponding one of the auxiliary batteries241,242, and243to the main battery230. In this case, powers supplied from the auxiliary batteries241,242, and243via the bypass circuits256,261, and266may assist a function of an energy source for driving the motor of the main battery230.

Meanwhile, the power converters255,260, and265may operate in an individual manner in accordance with voltages charged in the auxiliary batteries241,242, and243, respectively. Accordingly, each of the power converters255,260, and265may independently operate irrespective of operation of the remaining ones of the power converters255,260, and265.

Although the auxiliary battery power conversion device is shown as including three auxiliary batteries241,242, and243and three power converters255,260, and265in this embodiment, this is only illustrative, and the auxiliary battery power conversion device may include various numbers of auxiliary batteries and power converters.

FIG.4shows an example of a circuit of the auxiliary battery power conversion device according to the embodiment ofFIG.3.

Referring toFIG.4, the bypass circuits256,261, and266include respective diodes D31, D33, and D35and respective switches SW31, SW33, and SW35.

In addition, the buck converters257,262, and267include buck switches SW32, SW34, and SW36, respectively.

In this case, each of the buck switches SW32, SW34, and SW36operates to be rapidly switched on/off when the voltage of a corresponding one of the auxiliary batteries241,242, and243connected thereto is higher than the voltage of the main battery230. On the other hand, each of the buck switches SW32, SW34, and SW36does not operate when the voltage of the corresponding one of the auxiliary batteries241,242, and243is not higher than the voltage of the main battery230. Accordingly, when each of the auxiliary batteries241,242, and243has a higher voltage than the voltage of the main battery230, the voltage thereof is converted into a voltage for recharging the main battery230through a corresponding one of the buck converters257,262, and267respectively connected to the auxiliary batteries241,242, and243, thereby recharging the main battery230.

Meanwhile, each of the buck converters257,262, and267may be configured through further inclusion of two capacitors, one inductor, and one diode.

For example, the first buck converter257may be configured through inclusion of first and second capacitors C31and C32, a first inductor L31, a second diode D32, and the first buck switch SW32.

In addition, the second buck converter262may be configured through inclusion of third and fourth capacitors C33and C34, a second inductor L32, a fourth diode D34, and the second buck switch SW34.

In addition, the third buck converter267may be configured through inclusion of fifth and sixth capacitors C35and C36, a third inductor L33, a sixth diode D36, and the third buck switch SW36.

In accordance with this embodiment, it may be possible to minimize the capacity of the relatively expensive buck converter while maximizing the capacity of the relatively inexpensive bypass circuit and, thereby achieving a reduction in cost. For example, the system may be configured by using a converter having a capacity of 1 kW as the buck converter while using a bypass circuit having a capacity of 6 kW as the bypass circuit.

FIG.5shows a power conversion system according to another exemplary embodiment of the present invention.

Referring toFIG.5, the power conversion system according to this embodiment includes an AC power source510, an on-board charger520, a main battery530, an auxiliary battery540, and a power converter550.

AC power from the AC power source510is applied to the on-board charger520in order to recharge the main battery530. In this case, the AC power source510may be a power source installed in external charging equipment.

The on-board charger520converts an AC voltage from the AC power source510into a DC voltage capable of recharging the main battery530, and then supplies the DC voltage to the main battery530. The on-board charger520includes a power factor compensation circuit521, a link capacitor C51, an LLC circuit525, a transformer T51, and a rectifier circuit529. In this case, the power factor compensation circuit521, the link capacitor C51, the LLC circuit525, the transformer T51, and the rectifier circuit529may be implemented in various topologies in the present technical field.

The main battery530is recharged with power, and supplies the charged power to a motor (not shown), thereby supplying rotation force to a wheel of a vehicle. In this case, the main battery530may be recharged by DC charging power supplied from the on-board charger520or the auxiliary battery540. The main battery530may be a low-voltage output type battery and, may be, for example, a 48V standard battery. In this case, although the main battery530is of a 48V standard, the main battery530may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof.

The auxiliary battery540is constituted by a plurality of auxiliary batteries541,542, and543, and assists a function of an energy source for recharging the main battery530or driving the motor of the main battery530. In this case, the auxiliary battery540may be a low-voltage output type battery and, may be, for example, a 48V standard battery. Although the auxiliary battery540is of a 48V standard, the auxiliary battery540may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof, similarly to the main battery530.

In this case, the auxiliary battery540may be provided in the form of a swappable battery.

The power converter550converts a voltage of the auxiliary battery540into a voltage having a level suitable for charging the main battery530. In this case, since both the auxiliary battery540and the main battery530have DC voltages, the power converter550functions as a DC-DC converter. A concrete structure of the power converter550will be described in detail with reference to an auxiliary battery power conversion device ofFIGS.6and7which will be described later.

FIG.6shows an auxiliary battery power conversion device according to another exemplary embodiment of the present invention.

Referring toFIG.6, the power conversion device according to this embodiment includes a main battery530, an auxiliary battery540, and a power converter550. In this case, the auxiliary battery power conversion device ofFIG.6may constitute a part of the power conversion system ofFIG.5.

The main battery530is recharged with power, and supplies the charged power to a motor (not shown), thereby supplying rotation force to a wheel of a vehicle. In this case, the main battery530may be recharged by DC charging power supplied from the auxiliary battery540. The main battery530may be a low-voltage output type battery and, may be, for example, a 48V standard battery. In this case, although the main battery530is of a 48V standard, the main battery530may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof.

The auxiliary battery540assists a function of an energy source for recharging the main battery530or driving the motor of the main battery530.

The auxiliary battery540may include a plurality of auxiliary batteries541,542, and543.

In this case, the auxiliary battery540may be a low-voltage output type battery and, may be, for example, a 48V standard battery. Although the auxiliary battery540is of a 48V standard, the auxiliary battery540may have an output in various ranges of 30 to 60V in accordance with a state of charge (SOC) thereof, similarly to the main battery530.

In this case, the auxiliary battery540may be provided in the form of a swappable battery.

The power converter550converts a voltage of the auxiliary battery540into a voltage having a level suitable for charging the main battery530. In this case, the power converter550may include one buck converter570, a plurality of bypass circuits555,560, and565, and a plurality of relay switches S51, S52, and S53.

In this case, the plurality of bypass circuits555,560, and565and the plurality of relay switches S51, S52, and S53may be configured to be equal in number to the plurality of auxiliary batteries541,542, and543.

Referring toFIG.6, each of the first to third auxiliary batteries541,542, and543is connected to the corresponding one of the bypass circuits555.560, and565and a corresponding one of the relay switches S51, S52, and S53. Each of the relay switches S51, S52, and S53connects or disconnects the corresponding auxiliary battery and the corresponding buck converter to or from each other in accordance with ON/OFF control thereof.

In addition, power supply paths of the auxiliary batteries541,542, and543connected to the main battery530are switched by the buck converter570and respective bypass circuits555,560, and565connected to the auxiliary batteries541,542, and543.

In this case, when voltages of the auxiliary batteries541,542, and543respectively connected to the relay switches S51, S52, and S53are higher than the voltage of the main battery530, the buck converter570drops the voltages of the auxiliary batteries541,542, and543, and supplies the dropped voltages to the main battery530. In this case, the voltages supplied to the main battery530through the buck converter570may be used to recharge the main battery530.

Meanwhile, a circuit of each of the bypass circuits555,560, and565operates when the voltage of a corresponding one of the auxiliary batteries541,542, and543connected thereto is equal to the voltage of the main battery530, thereby electrically connecting the corresponding one of the auxiliary batteries541,542, and543to the main battery230. In this case, powers supplied from the auxiliary batteries541,542, and543via the bypass circuits555,560, and565may assist a function of an energy source for driving the motor of the main battery530.

In this case, the relay switches S51, S52, and S53may be set such that only one thereof is switched on at one time.

In addition, the relay switches S51, S52, and S53may be set to be sequentially switched on in accordance with a predetermined priority order or a predetermined condition.

For example, the first to third relay switches S51, S52, and S53may be sequentially switched on in an order of the first, second, and third relay switches S51, S52, and S53respectively connected to the first, second, and third auxiliary batteries541,542, and543. When the voltage of one of the first to third auxiliary batteries541,542, and543becomes equal to the voltage of the main battery530, the relay switch connected to the auxiliary battery, the voltage of which becomes equal to the voltage of the main battery530, may be switched off, and the relay switch next to the former relay switch may then be switched on.

In detail, when voltages of all of the first to third auxiliary batteries541,542, and543are higher than the voltage of the main battery530, the first relay switch S51is switched on until the voltage of the first auxiliary battery541becomes equal to the voltage of the main battery530and, as such, the main battery530is recharged with the voltage from the first auxiliary battery541. When the voltage of the first auxiliary battery541becomes equal to the voltage of the main battery530, the first relay switch S51is switched off and, as such, current may flow between the first auxiliary battery541and the main battery530via the first bypass circuit555. In this case, the first auxiliary battery541may assist a function of an energy source for driving the motor of the main battery530.

In this case, when the voltage of the second auxiliary battery542is higher than the voltage of the main battery530, the second relay switch S52is switched on until the voltage of the second auxiliary battery542becomes equal to the voltage of the main battery530and, as such, the main battery530is recharged with the voltage from the second auxiliary battery542. When the voltage of the second auxiliary battery542becomes equal to the voltage of the main battery530, the second relay switch S52is switched off and, as such, current may flow between the second auxiliary battery542and the main battery530via the second bypass circuit560. In this case, the second auxiliary battery542may assist a function of an energy source for driving the motor of the main battery530.

In this case, when the voltage of the third auxiliary battery543is higher than the voltage of the main battery530, the third relay switch S53is switched on until the voltage of the third auxiliary battery543becomes equal to the voltage of the main battery530and, as such, the main battery530is recharged with the voltage from the third auxiliary battery543. When the voltage of the third auxiliary battery543becomes equal to the voltage of the main battery530, the third relay switch S53is switched off and, as such, current may flow between the third auxiliary battery543and the main battery530via the third bypass circuit565. In this case, the third auxiliary battery543may assist a function of an energy source for driving the motor of the main battery530.

Meanwhile, although not shown, the auxiliary battery power conversion device according to this embodiment may further include a relay controller and, as such, may control ON/OFF of the relay switches S51, S52, and S53in accordance with a predetermined condition or a predetermined priority order.

FIG.7shows an example of a circuit of the auxiliary battery power conversion device according to the embodiment ofFIG.6.

Referring toFIG.7, the first to third bypass circuits555,560, and565include respective diodes D51, D52, and D53and respective bypass switches SW5i, SW52, and SW53.

In addition, the buck converter570includes two capacitors C52and C54, one inductor L52, one diode D54, and one buck switch SW54.

In this case, the buck switch SW54operates to be rapidly switched on/off when voltages of the auxiliary batteries541,542, and543electrically connected thereto are higher than the voltage of the main battery530. On the other hand, the buck switch SW54does not operate when the voltages of the auxiliary batteries541,542, and543are not higher than the voltage of the main battery230. Accordingly, when each of the auxiliary batteries541,542, and543has a higher voltage than the voltage of the main battery530, and the relay switches S51, S52, and S53connected between respective auxiliary batteries541,542, and543and the buck converter570are switched on, the voltage of each of the auxiliary batteries541,542, and543is converted into a voltage for recharging the main battery530through the buck converter570, thereby recharging the main battery530.

Although the auxiliary battery540is shown as including three auxiliary batteries, that is, the first to third auxiliary batteries541,542, and543, this is only illustrative, and the auxiliary battery540may include various numbers of auxiliary batteries.

In accordance with this embodiment, the auxiliary batteries are sequentially discharged and, as such, only the discharged auxiliary batteries may first be replaced. Accordingly, it may be possible to not only efficiently manage the capacity of the auxiliary battery, but also to reduce the cost incurred to configure the system through a reduction in circuit parts.

In accordance with the exemplary embodiments of the present invention described heretofore, it may be possible to not only stably manage a state of charge of the auxiliary battery, but also to effectively control charging current, and, as such, an increase in the range of the electric vehicle and an enhancement in power performance of the electric vehicle may be achieved.

In addition, the user may directly replace a discharged auxiliary battery with a new one in a place where a battery is replaceable.

Furthermore, it may be possible to achieve a reduction in cost by minimizing the capacity of the buck converter while designing the bypass circuit to have a high capacity.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.