KR102479366B1 - Battery Charger and Control Methods - Google Patents

Abstract

The LLC resonant converter according to the present embodiment includes a plurality of high-side switches and a plurality of low-side switches, and operates in a half-bridge mode when an output voltage output to a battery is in a first voltage range, and the output voltage is in the first voltage range. When the second voltage range is greater than the voltage range, it operates in full bridge mode.

Description

Battery charging device and control method {Battery Charger and Control Methods}

The present invention relates to a battery charging device and control method.

Due to accelerating global warming, depletion of natural resources, increasing fuel prices and economic problems, hybrid electric vehicles, plug-in hybrid electric vehicles (PHEVs), battery electric vehicles and fuel cell vehicles are becoming increasingly popular. Electric propulsion vehicles are gradually increasing.

These vehicles generally require batteries as an energy source. Among them, a plug-in hybrid electric vehicle or battery electric vehicle requires a battery pack with a higher capacity and a larger size than other vehicles because the battery is the main energy source of the vehicle.

These high energy density battery packs are charged from an AC power grid through an AC/DC converter, commonly referred to as a battery charger. In order to have low harmonics and high efficiency for the AC power grid, most of the battery chargers generally consist of an AC/DC converter, a variable capacitor and an isolated DC/DC converter connected configuration. In general, the AC/DC converter uses a 2-level AC/DC converter and the DC/DC converter uses a phase shift full bridge converter. A battery charger with this configuration can achieve high efficiency only at the maximum voltage, resulting in high efficiency over a wide charging voltage range. There is a problem that cannot be operated with .

The present embodiment is intended to provide a battery charging device and control method capable of high-efficiency charging in a battery charging voltage range.

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above technical problem, the LLC resonant converter according to the present embodiment includes a plurality of upper switches and a plurality of lower switches, and operates in half bridge mode when the output voltage output to the battery is in the first voltage range, , When the output voltage is in the second voltage range greater than the first voltage range, the full bridge mode is operated.

The first voltage range includes a duty-controlled 1-1 voltage range and a frequency-controlled 1-2 voltage range, and the second voltage range includes a duty-controlled 2-1 voltage range and a frequency-controlled second voltage range. Can include -2 voltage range.

The 1-1 voltage range may have a smaller value than the 1-2 voltage range, and the 2-1 voltage range may have a smaller value than the 2-2 voltage range.

The first charging voltage range for charging the battery is included in the 1-2 voltage range, and the second charging voltage range greater than the first charging voltage range for charging the battery is included in the 2-2 voltage range. can

The resonant point of the LLC resonant converter may have a value designed to output the lowest voltage in the 1-2 voltage range in the half-bridge mode.

The resonance point of the LLC resonance converter may have a value designed to output the lowest voltage in the 2-2nd voltage range in the full bridge mode.

At least a part of the 1-2nd voltage range may overlap with the 2-1st voltage range.

The frequency control in the first voltage range controls the frequency between the frequency at which the output voltage is maximum in the half-bridge mode and the resonance frequency of the LLC resonant converter, and the frequency control in the second voltage range, The frequency can be controlled between the frequency at which the output voltage is maximum in the full bridge mode and the resonance frequency of the LLC resonant converter.

AC power supplying power; an AC/DC converter connected to the AC power; a capacitor connected to the AC/DC converter and whose voltage is varied by the AC/DC converter; The LLC resonant converter of claim 1 connected to the capacitor; and a battery charged from the LLC resonant converter.

A battery charging control method according to the present embodiment includes checking a voltage output to a battery; and operating in a half-bridge mode when the checked voltage is included in the first voltage range, and operating in full-bridge mode when the checked voltage is included in a second voltage range greater than the first voltage range. can do.

When the checked voltage is included in the 1-1 voltage range included in the first voltage range, it operates as duty control, and when included in the 1-2 voltage range greater than the 1-1 voltage range, as frequency control. It can work.

When the checked voltage is included in the 2-1 voltage range included in the second voltage range, the duty control operates and when included in the 2-2 voltage range greater than the 2-1 voltage range, the frequency control It can work.

According to this embodiment, it is possible to charge the battery in a method capable of increasing the efficiency of the battery charging device in the main charging range of the battery, and thus, it is possible to prevent unnecessary power loss.

In addition, overload due to mode change may be prevented by partially overlapping the half-bridge mode and full-bridge mode control sections of the battery charging device.

In addition, while covering a wide charging range, it is possible to operate with optimum efficiency by changing the mode and control method according to each charging range.

Effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 shows a block diagram of a battery charging device.
2 shows a circuit diagram of a battery charging device.
3 to 8 are diagrams for explaining a battery charging device and a control method according to the present embodiment.

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

However, the technical idea of the present invention is not limited to some of the described embodiments, but may be implemented in a variety of different forms, and if it is within the scope of the technical idea of the present invention, one or more of the components among the embodiments can be selectively implemented. can be used in combination or substitution.

In addition, terms (including technical and scientific terms) used in this embodiment have meanings that can be generally understood by those of ordinary skill in the art to which this embodiment belongs, unless explicitly specifically defined and described. The meaning of commonly used terms, such as terms defined in a dictionary, can be interpreted in consideration of the contextual meaning of related technology.

In addition, terms used in the present embodiment are for describing the embodiments and are not intended to limit the present invention.

In this specification, the singular form may also include the plural form unless otherwise specified in the phrase, and when described as "at least one (or more than one) of A and (and) B and C", A, B, and C are combined. may include one or more of all possible combinations.

In addition, in describing the components of this embodiment, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the term is not limited to the nature, order, or order of the corresponding component.

And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, the component is directly 'connected', 'coupled', or 'connected' to the other component. In addition to the case, it may include cases where the component is 'connected', 'combined', or 'connected' due to another component between the component and the other component.

In addition, when it is described as being formed or disposed on the "upper (above)" or "lower (below)" of each component, "upper (above)" or "lower (below)" means that two components are directly connected to each other. It includes not only the case of being in contact, but also the case where one or more other components are formed or disposed between two components. In addition, when expressed as "upper (above)" or "lower (down)", the meaning of not only an upward direction but also a downward direction may be included based on one component.

Hereinafter, the configuration of the battery charging device will be described with reference to the drawings.

1 is a block diagram of a battery charging device, and FIG. 2 is a circuit diagram of the battery charging device.

In general, the battery charging device 100 is connected to an AC power source 110 that supplies power, an AC / DC converter 120 connected to the AC power source 110, and an AC / DC converter 120 connected to the AC / DC converter ( 120), a capacitor 130 whose voltage is variable, a DC/DC converter 140 connected to the capacitor 130, and a battery 150 charged from the DC/DC converter 140.

AC/DC converter 120 of V _BUS 130 Varying the voltage contributes to optimal operation of the DC/DC converter 140. When the AC power source 110 has a single-phase input, the AC/DC converter 120 may be a Boost PFC (Power-Factor-Corrected) converter, and the DC/DC converter 140 may be a phase shift full bridge converter (PSFB, Phase Shift Full Bridge Converter). When the AC power supply 110 is a three-phase input, the AC/DC converter 120 may be a 3-level PFC converter and the DC/DC converter 140 may be a 3-level PSFB. This is merely illustrative, and it goes without saying that various types of converters may be used.

The PSFB has the advantages of naturally achieving zero-voltage-switching (ZVS), low output current ripple, and simple structure and control. However, the PSFB has the highest efficiency when using the maximum duty, and as the duty decreases, the efficiency decreases due to a circulating current problem. Specifically, the PSFB has a problem in that the ZVS range is narrow for a wide operating range, the circulating current is large, and high voltage stress is generated in the rectifier stage, resulting in low overall efficiency.

In the case of electric vehicles currently being mass-produced, the layer voltage ranges of 300V to 400V and 600V to 850V are most commonly used. Electric vehicle chargers need to operate with high efficiency at all output voltages, and efficiency is especially important in the main charging area.

Through the LLC resonant converter according to the present embodiment, it is possible to operate with high efficiency in an electric vehicle charging voltage range, and in particular, it is possible to increase efficiency in the main charging region.

The DC/DC converter 140 according to the present embodiment operates using an LLC resonant converter, and a description thereof will be made in detail below.

Hereinafter, the configuration and control method of the LLC resonant converter 140 according to the present embodiment will be described with reference to the drawings.

The LLC resonant converter 140 may include a plurality of high-side switches and a plurality of low-side switches. The plurality of upper switches may include a first switch S1 and a fourth switch S4, and the plurality of lower switches may include a second switch S2 and a third switch S3. A plurality of passive elements may be included on a bridge node (between terminals a and b) connecting the plurality of upper switches and the plurality of lower switches. For example, a plurality of passive elements may be included in a node connecting the first and third switches S1 and S3 and the fourth and second switches S4 and S2. Between the terminals a and b, a resonance capacitor (Cr), a resonance inductor (Lr), and a magnetizing inductor (Lm) are connected in series, and a primary winding (Np) connected in parallel to the magnetization inductor (Lm) may be included. This is a general configuration of the LLC resonant converter, and detailed description is omitted.

Referring to FIG. 3, in the half-bridge mode operation of the LLC resonant converter 140, a voltage of 1/2 the size of the input voltage Vin is applied between terminals a and b as S1 and S3 alternately switch. That is, in the switching states of S1 turn-on and S3 turn-off, the voltage of +1/2 Vin is applied, and in the turn-off state of S1 and the turn-on state of S3, the voltage of -1/2 Vin is applied. is applied and transmitted to the secondary side rectification output unit, respectively.

Referring to FIG. 5, in the full bridge mode operation of the LLC resonant converter 140, a voltage having the same magnitude as the input voltage Vin is applied between terminals a and b as S1 and S3 and S4 and S2 alternately operate. do. That is, +Vin voltage is applied in the switching state of S1 and S2 turn-on and S3 and S4 turn-off, and -Vin voltage is applied in the switching state of S1 and S2 turn-off and S3 and S4 turn-on. A voltage of is applied and delivered to the secondary rectified output.

<Equation 1>

<Equation 2>

은 공진 주파수를 의미하고,

는 스위치 주파수를 의미한다. Equation 1 is an equation for the input voltage and output voltage in the half-bridge mode of the LLC resonant converter, and Equation 2 is an equation for the input voltage and output voltage in the full-bridge mode. Vin is the input voltage input to the LLC resonant converter, Vo is the output voltage output from the LLC resonant converter, Lr is the inductance of the resonant inductor, Cr is the capacitance of the resonant capacitor,

is the resonant frequency,

is the switch frequency.

)가 고정되고, 스위치 듀티 제어 또는 주파수 제어를 통해 추가적으로 출력 전압의 이득을 조절할 수 있다. 여기서, 듀티 제어는 LLC 공진 컨버터(140)의 스위치 온-오프되는 한 사이클에서 온되는 비율을 제어하는 것을 의미하고, 주파수 제어는 LLC 공진 컨버터(140)의 스위치 온-오프되는 한 사이클의 시간 또는 주기를 제어하는 것을 의미한다. Referring to Equations 1 and 2 above, when the LLC resonant converter 140 operates in full-bridge mode, it may have twice as much voltage gain as when operating in half-bridge mode. In addition, the resonant frequency (

) is fixed, and the gain of the output voltage can be additionally adjusted through switch duty control or frequency control. Here, the duty control refers to controlling the ratio of the LLC resonant converter 140 to be turned on in one cycle in which the LLC resonant converter 140 is switched on and off, and the frequency control refers to the time of one cycle in which the LLC resonant converter 140 is switched on and off, or It means to control the cycle.

Hereinafter, a charging control method of the LLC resonant converter according to an output voltage range output to a battery will be described with reference to FIGS. 7 and 8 .

The output voltage output to the battery 150 by the LLC resonant converter 140 may include a first voltage range (H) and a second voltage range (F). The first voltage range (H) may have a smaller value than the second voltage range (F). The first voltage range H and the second voltage range F may not overlap. The first voltage range H and the second voltage range F may partially overlap. The first voltage range (H) and the second voltage range (F) may be included in the charging voltage at which the electric vehicle is charged, 150V to 1000V. The first voltage range (H) may be 150V to 500V, and the second voltage range (F) may be 500V to 1000V. The first voltage range (H) may be 150V to 600V, and the second voltage range (F) may be 400V to 1000V.

When the output voltage output to the battery 150 is a value within the first voltage range (H), the LLC resonant converter 140 may operate in a half bridge mode. The first voltage range H operating in the half-bridge mode may include a duty-controlled 1-1 voltage range H1 and a frequency-controlled 1-2 voltage range H2. The 1-1st voltage range H1 may have a smaller voltage value than the 1-2nd voltage range H2. The 1-1st voltage range H1 and the 1-2nd voltage range H2 may not overlap. The 1-1 voltage range H1 and the 1-2 voltage range H2 may partially overlap. The 1-1st voltage range H1 may be 150V to 300V, and the 1-2nd voltage range H2 may be 300V to 500V. The 1-1st voltage range H1 may be 150V to 300V, and the 1-2nd voltage range H2 may be 300V to 600V.

When the output voltage output to the battery 150 is in the second voltage range F, the LLC resonant converter 140 may operate in the full bridge mode. The second voltage range F operating in the full bridge mode may include a duty-controlled 2-1 voltage range F1 and a frequency-controlled 2-2 voltage range F2. The 2-1st voltage range (F1) may have a smaller voltage value than the 2-2nd voltage range (F2). The 2-1st voltage range F1 and the 2-2nd voltage range F2 may not overlap. The 2-1st voltage range F1 and the 2-2nd voltage range F2 may partially overlap. The 2-1st voltage range F1 may be 500V to 600V, and the 2-2nd voltage range F2 may be 600V to 1000V. The 2-1st voltage range F1 may be 400V to 600V, and the 2-2nd voltage range F2 may be 600V to 1000V. In the full bridge mode, the duty may be fixed to a maximum of 50% in the 2-2nd voltage range operated by frequency control. In the frequency-controlled voltage range, it can operate with maximum efficiency at maximum duty.

As described above, the battery charging device according to the present embodiment changes the operation mode of the LLC resonant converter 140 according to the output voltage range output to the battery, and through this, it can operate with maximum efficiency in each output voltage range.

Referring to FIG. 8 , at least a portion of the 1-2nd voltage range H2 may overlap the 2-1st voltage range F1. Through this, when the output voltage range output to the battery corresponds to both the 1-2 voltage range H2 and the 2-1 voltage range F1, overload due to mode change can be prevented. For example, as shown in FIG. 7, when the 1-2 voltage range H2 and the 2-1 voltage range F1 do not overlap, if the output voltage range output to the battery is 400V to 550V, the output voltage is 500V. When a mode change occurs, overload may occur accordingly. On the other hand, when the 1-2 voltage range H2 and the 2-1 voltage range F1 overlap as shown in FIG. 8, the mode change may not occur if the output voltage range output to the battery is 400V to 550V. . That is, as shown in FIG. 8 , it is possible to reduce the possibility of mode change by designing the control so that the 1-2 voltage range H2 and the 2-1 voltage range F1 overlap.

The voltage range for charging the battery may include a first charging voltage range (A) and a second charging voltage range (B). The first charging voltage range (A) may have a smaller value than the second charging voltage range (B). For example, the main charging voltage ranges charged in currently mass-produced electric vehicles are 300V to 450V and 600V to 850V, so the first charging voltage range (A) may correspond to 300V to 450V, and the second charging voltage range ( B) may correspond to 600V to 850V. This corresponds to exemplary numerical information and is not particularly limited thereto.

The voltage output to the battery may vary depending on the state of charge of the battery. For example, when the battery is in an uncharged state, it may be charged with the maximum voltage of the charging voltage range, and when the battery is in an overcharged state, it may be charged with the minimum voltage in the charging voltage range.

The first charging voltage range (A) is included in the 1-2 voltage range (H2), and the second charging voltage range (B) greater than the first charging voltage range (A) is the 2-2 voltage range (F2) can be included in In the half bridge mode (H), the lowest voltage of the 1st-2nd voltage range (H2) frequency controlled may be the same as the lowest voltage of the first charging voltage range (A). The lowest voltage of the 2-2nd voltage range (F2) frequency controlled in the full bridge mode (F) may be the same as the lowest voltage of the second charging voltage range (B).

In the duty-controlled 1-1 voltage range H1 and 2-1 voltage range F1, the output voltage may increase as the duty increases. At this time, the switch frequency may be fixed. For example, the switch frequency may be fixed at the resonant frequency. In duty control mode, it can operate with maximum efficiency at maximum duty. Therefore, it is possible to improve efficiency by operating at maximum duty at the maximum voltage of the 1-1st voltage range H1 and the maximum voltage of the 2-1st voltage range F1.

In the frequency-controlled 1-2 voltage range H2 and 2-2 voltage range F2, the output voltage may increase as the frequency decreases. At this time, the switch duty may be fixed at 50%, which is the maximum value.

Specifically, the resonance point of the LLC resonance converter 140 may be designed such that the lowest voltage in the 1-2nd voltage range (H2) is output in the half-bridge mode (H). The resonance point of the LLC resonance converter 140 may be designed so that the lowest voltage in the 2-2 voltage range F2 is output in the full bridge mode F. That is, the inductance value of the resonance inductor (Lr) and the capacitance value of the resonance capacitor (Cr) of the LLC resonance converter 140 are the resonance at which the lowest voltage in the 1-2 voltage range (H2) is output in the half bridge mode (H). It can be designed to have a frequency. The inductance value of the resonance inductor (Lr) and the capacitance value of the resonance capacitor (Cr) of the LLC resonance converter 140 determine the resonance frequency at which the lowest voltage in the 2-2nd voltage range (F2) is output in the full bridge mode (F). can be designed to have The output voltage according to the full-bridge mode (F) operation has a value twice the output voltage according to the half-bridge mode (H) operation. Therefore, the lowest voltage of the 2nd-2nd voltage range (F2) frequency-controlled in the full bridge mode (F) is twice the lowest voltage of the 1-2nd voltage range (H2) frequency-controlled in the half-bridge mode (H). can have a value of

The frequency control in the first voltage range (H) controls the frequency between the frequency at which the output voltage is maximum in the half-bridge mode and the resonance frequency of the LLC resonant converter 140. For example, frequency control in the first voltage range (H) may be controlled between the first frequency and the second frequency. The first frequency may have a greater value than the second frequency. Referring to FIG. 4 , the first frequency may have a value of 90 kHz having a value within the error range, and the second frequency may have a value of 60 kHz having a value within the error range. That is, in the frequency control in the first voltage range H, the output voltage may increase as the frequency decreases.

The frequency control in the second voltage range (F) controls the frequency between the frequency at which the output voltage is maximum in the full bridge mode and the resonance frequency of the LLC resonant converter 140. For example, frequency control in the second voltage range (F) may be controlled between the third frequency and the fourth frequency. The third frequency may have a greater value than the fourth frequency. Referring to FIG. 6 , the third frequency may have a value of 90 kHz with an error range, and the fourth frequency may have a value of 60 kHz with a value within the error range. That is, in the frequency control in the second voltage range F, the output voltage may increase as the frequency decreases. And, the lowest voltage of the 2-2nd voltage range (F2) frequency-controlled in the full bridge mode (F) is twice the lowest voltage in the 1-2nd voltage range (H2) frequency-controlled in the half-bridge mode (H). In the case of having a value of , the first frequency and the third frequency may have the same value. The first frequency and the third frequency may have the same value as the resonant frequency of the LLC resonant converter 140 .

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art can realize that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. you will be able to understand Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

100: battery charging device 110: AC power
120: AC/DC converter 130: variable capacitor
140: DC/DC converter 150: battery

Claims (12)

Including a plurality of upper switches and a plurality of lower switches,
When the output voltage output to the battery is in a first voltage range, it operates in half-bridge mode, and when the output voltage is in a second voltage range greater than the first voltage range, it operates in full-bridge mode,
The first voltage range includes a 1-1 voltage range of duty control and a 1-2 voltage range of frequency control,
The second voltage range includes a duty-controlled 2-1 voltage range and a frequency-controlled 2-2 voltage range,
At least a part of the 1-2 voltage range overlaps the 2-1 voltage range LLC resonant converter. delete According to claim 1,
The 1-1 voltage range has a smaller value than the 1-2 voltage range,
The 2-1 voltage range LLC resonant converter having a value smaller than the 2-2 voltage range. According to claim 1,
The first charging voltage range for charging the battery is included in the 1-2 voltage range,
A second charging voltage range greater than the first charging voltage range for charging the battery is included in the 2-2 voltage range. According to claim 1,
The resonance point of the LLC resonant converter has a value designed so that the lowest voltage in the 1-2 voltage range is output in the half bridge mode. According to claim 1,
The resonant point of the LLC resonant converter has a value designed so that the lowest voltage in the 2-2 voltage range is output in the full bridge mode. delete According to claim 1,
Frequency control in the first voltage range,
Control the frequency between the frequency at which the output voltage is maximum in the half bridge mode and the resonance frequency of the LLC resonant converter;
Frequency control in the second voltage range,
An LLC resonant converter for controlling a frequency between a frequency at which the output voltage is maximum in the full bridge mode and a resonant frequency of the LLC resonant converter. AC power supplying power;
an AC/DC converter connected to the AC power;
a capacitor connected to the AC/DC converter and whose voltage is varied by the AC/DC converter;
The LLC resonant converter of claim 1 connected to the capacitor; and
A battery charging device including a battery charged from the LLC resonant converter. Checking the voltage output to the battery; and
Operating in half bridge mode when the checked voltage is included in the first voltage range, and operating in full bridge mode when the checked voltage is included in a second voltage range greater than the first voltage range, ,
When the checked voltage is included in the 1-1 voltage range included in the first voltage range, it operates as duty control, and when included in the 1-2 voltage range greater than the 1-1 voltage range, as frequency control. operate,
When the checked voltage is included in the 2-1 voltage range included in the second voltage range, the duty control operates and when included in the 2-2 voltage range greater than the 2-1 voltage range, the frequency control operating
At least a part of the 1-2 voltage range overlaps the 2-1 voltage range.
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