Battery charging apparatus

Abstract

A battery charging device comprises: a bidirectional charger including a first switching circuit connected to an AC terminal, a second switching circuit connected to a battery, and a transformer connected between the first switching circuit and the second switching circuit; and a controller that switches a leg included in the first switching circuit based on a first carrier wave and a first duty command, and switches a leg included in the second switching circuit based on a second carrier wave and a second duty command, wherein the phase of the second carrier wave relative to the phase of the first carrier wave is adjusted by a phase shift angle according to an active power command, and the phase of the second duty command is adjusted according to a reactive power command.

Description

Technology Field

[0001] The present invention relates to a battery charging device that transmits electrical energy bidirectionally between an external power source / external load and a battery. Background Technology

[0002] Recently, driven by the global trend of reducing carbon dioxide emissions, there has been a significant increase in demand for electrified vehicles that generate driving power by driving motors with electrical energy stored in energy storage devices, such as batteries, instead of typical internal combustion engine vehicles that generate driving power through the combustion of fossil fuels.

[0003] The electric vehicle is equipped with an on-board charger (OBC) that charges the battery from the grid power, and in particular, can perform V2G (Vehicle to Grid) and V2L (Vehicle to Load) modes by supplying energy stored in the battery to the grid power and electric load through a bidirectional on-board charger (OBC).

[0004] The matters described above as background technology are intended only to enhance understanding of the background of the present invention and should not be construed as an acknowledgment that they constitute prior art already known to those skilled in the art. The problem to be solved

[0005] Accordingly, the present invention aims to solve the technical problem of controlling the active power component and the reactive power component of apparent power in a bidirectional charger.

[0006] The technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0007] As a means to solve the above technical problem, the battery charging device may include a bidirectional charger comprising a first switching circuit connected to an AC terminal, a second switching circuit connected to a battery, and a transformer connected between the first switching circuit and the second switching circuit; and a controller that switches a leg included in the first switching circuit based on a first carrier wave and a first duty command, and switches a leg included in the second switching circuit based on a second carrier wave and a second duty command, wherein the phase of the second carrier wave relative to the phase of the first carrier wave is adjusted by a phase shift angle according to an active power command, and the phase of the second duty command is adjusted according to a reactive power command.

[0008] In addition, as a means to solve the above technical problem, the battery charging device may include a bidirectional charger comprising a first switching circuit connected to an AC terminal, a second switching circuit connected to a battery, and a transformer connected between the first switching circuit and the second switching circuit; and a controller that switches a leg included in the first switching circuit based on a first carrier wave and a first duty command, and switches a leg included in the second switching circuit based on a second carrier wave and a second duty command, wherein the phase of the second carrier wave relative to the phase of the first carrier wave is adjusted by a phase shift angle according to an effective voltage command, and the phase of the second duty command is adjusted according to an reactive voltage command. Effects of the invention

[0009] According to the present invention, the phase of a carrier wave for pulse width modulation (PWM) control is adjusted in a phase shift control manner according to an active power command, and the phase of a duty command representing a switching duty is adjusted according to a reactive power command, thereby enabling control of the active power component and the reactive power component of the apparent power in a bidirectional charger.

[0010] In addition, according to the present invention, by setting the polarity of the phase shift angle according to the active power command to be the same as the polarity of the instantaneous power for the AC terminal of the bidirectional charger, the instability of the current that occurs when adjusting the phase of the duty command according to the reactive power command can be mitigated.

[0011] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0012] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a drawing illustrating an example of a battery charging device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the process of a control unit according to an embodiment of the present invention controlling the active power component and the reactive power component of a bidirectional charger. FIG. 3 is a block diagram illustrating the configuration of a first controller that controls the execution of a charging mode and a V2G mode according to an embodiment of the present invention. FIGS. 4 and 5 are waveforms of the current and voltage of a bidirectional charger when a first controller according to an embodiment of the present invention controls the active power component and the reactive power component. FIG. 6 is a circuit diagram according to one embodiment of the phase detection unit illustrated in FIG. 3. FIGS. 7 and FIGS. 8 are drawings for explaining the operation of the phase detection unit illustrated in FIGS. 3. FIGS. 9 and FIGS. 10 are waveform diagrams illustrating the operation of reversing the polarity of the phase transition angle when controlling a reactive power component according to an embodiment of the present invention. FIG. 11 is a block diagram illustrating the configuration of a second controller that controls the execution of a V2L mode according to an embodiment of the present invention. FIG. 12 is a waveform of the current and voltage of a bidirectional charger when a second controller according to an embodiment of the present invention controls the active power component and the reactive power component. Specific details for implementing the invention

[0013] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components regardless of drawing symbols are given the same reference number, and redundant descriptions thereof will be omitted.

[0014] In describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art may obscure the essence of the embodiments disclosed in this specification, such detailed description is omitted. Furthermore, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention.

[0015] In the description of the following embodiments, the term "pre-set" means that the numerical value of a parameter is predetermined when the parameter is used in a process or algorithm. Depending on the embodiment, the numerical value of the parameter may be set when the process or algorithm starts or during the period in which the process or algorithm is executed.

[0016] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0017] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0018] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0019] In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0020] A controller may include a communication device that communicates with other controllers or sensors to control the function it is responsible for, a memory that stores an operating system, logic instructions, and input / output information, and one or more processors that perform judgments, calculations, decisions, etc., necessary for controlling the function it is responsible for.

[0021] FIG. 1 is a drawing illustrating an example of a battery charging device according to an embodiment of the present invention. As shown in FIG. 1, the battery charging device may include a battery (10), a bidirectional charger (20), and a control unit (30).

[0022] The bidirectional charger (20) may have AC terminals (A1, A2) connected to a grid power source or an AC load, and DC terminals (D1, D2) connected to both ends of the battery (10). The bidirectional charger (20) may perform a charging mode that converts the AC voltage of the grid power source into a DC voltage to charge the battery (10) when the vehicle is stopped, and a discharging mode that converts the voltage of the battery (10) into an AC voltage and outputs it externally. The discharging mode may include a V2G (Vehicle to Grid) mode that supplies power from the battery (10) to the grid power source when the vehicle is stopped, and a V2L (Vehicle to Load) mode that supplies power from the battery (10) to an AC load when the vehicle is stopped or driving.

[0023] The bidirectional charger (20) includes a first switching circuit (21) connected to AC terminals (A1, A2) and a second switching circuit (22) connected to DC terminals (D1, D2), and may include a transformer (23) connected between the first switching circuit (21) and the second switching circuit (22) to electrically isolate the AC terminals (A1, A2) and the DC terminals (D1, D2). The transformer (23) includes a primary coil (L1), a secondary coil (L2), a magnetizing inductor (Lm), and a leakage inductor (Ls), and can convert current and voltage according to the winding ratio of the primary coil (L1) and the secondary coil (L2).

[0024] The first switching circuit (21) may include a plurality of legs (Q1-Q2, Q3-Q4, Q5-Q6), input inductors (Lg1, Lg2), and a clamp capacitor (Cc). Legs (Q1-Q2) may be connected to an AC terminal (A1) through an input inductor (Lg1) and may be connected to one end of the primary coil (L1) of the transformer (23). Legs (Q3-Q4) may be connected to an AC terminal (A1) through an input inductor (Lg2) and may be connected to the other end of the primary coil (L1) of the transformer (23). Legs (Q5-Q6) may be connected to an AC terminal (A2), and a clamp capacitor (Cc) may be connected between both ends of the plurality of legs (Q1-Q2, Q3-Q4, Q5-Q6). In this embodiment, a leg refers to a configuration in which a plurality of switch elements are connected, and each switch element can be implemented as a transistor.

[0025] The second switching circuit (22) may include legs (Q′1-Q′2) and legs (Q'3-Q'4) for forming a Dual Active Bridge (DAB) structure with legs (Q1-Q2) and legs (Q3-Q4) of the first switching circuit (21). Legs (Q′1-Q′2) and legs (Q'3-Q'4) are connected between DC terminals (D1, D2), and legs (Q′1-Q′2) may be connected to one end of the secondary coil (L2) of the transformer (23), and legs (Q'3-Q'4) may be connected to the other end of the secondary coil (L2) of the transformer (23). An output capacitor (Co) may be connected between DC terminals (D1, D2).

[0026] Since the bidirectional charger (20) according to the present embodiment is implemented with a power factor correction circuit (PFC) without a DC / DC converter, the components and area consumed by the bidirectional charger (20) can be reduced.

[0027] The control unit (30) includes a first controller (100) that controls the execution of a charging mode and a V2G mode, and a second controller (200) that controls the execution of a V2L mode, and can output a first switching signal (S1-S6) for switching a leg included in a first switching circuit (21) and a second switching signal (S'1-S'4) for switching a leg included in a second switching circuit (22). The first switching signal (S1-S6) corresponds to each of the switch elements (Q1-Q6) included in the first switching circuit (21), and the second switching signal (S'1-S'4) corresponds to each of the switch elements (Q'1-Q'4) included in the second switching circuit (22). In this embodiment, the phrase "a leg is switched" means that a plurality of switch elements included in the leg are switched complementarily.

[0028] More specifically, the control unit (30) can switch the legs (Q1-Q2) and legs (Q3-Q4) included in the first switching circuit (21) at a high frequency through an interleaving method with a 180° phase difference, and switch the legs (Q5-Q6) included in the first switching circuit (21) in synchronization with the set frequency (low frequency) of the grid power or AC load for synchronous rectification control.

[0029] Additionally, the control unit (30) can control the active power component of the apparent power of the bidirectional charger (20) by switching the legs (Q'1-Q'2, Q'3-Q'4) included in the second switching circuit (22) through a phase shift control method. The phase shift control method according to the present embodiment refers to a method of adjusting the switching phase of the legs (Q'1-Q'2, Q'3-Q'4) included in the second switching circuit (22) relative to the switching phase of the legs (Q1-Q2, Q3-Q4) included in the first switching circuit (21) by a phase shift angle according to the active power command. At this time, the switching frequency of the legs (Q1-Q2, Q3-Q4) included in the first switching circuit (21) and the switching frequency of the legs (Q'1-Q'2, Q'3-Q'4) included in the second switching circuit (22) can be set to be the same.

[0030] Meanwhile, the phase shift control method can control the active power component by adjusting the magnitude and direction of the current for the AC terminals (A1, A2), but it cannot control the reactive power component because it cannot adjust the phase of the current for the AC terminals (A1, A2) relative to the voltage for the AC terminals (A1, A2).

[0031] Accordingly, the present embodiment proposes a battery charging device that controls the active power component through a phase shift control method and controls the reactive power component by adjusting the phase of a duty command representing the switching duty of a leg included in the second switching circuit (22) according to the reactive power command.

[0032] A method of operation in which the control unit (30) controls the active power component and the reactive power component of the bidirectional charger (20) is explained with reference to FIG. 2.

[0033] FIG. 2 is a diagram illustrating the process of a control unit (30) according to an embodiment of the present invention controlling the active power component and the reactive power component of a bidirectional charger (20).

[0034] Referring to the top of FIG. 2, a first duty command (Dp) is shown, which represents the switching duty of a carrier wave for each of the switch elements (Q1, Q4) and switch elements (Q2, Q3) included in the first switching circuit (21) and a leg included in the first switching circuit (21). The value of the first duty command (Dp) can be set to a constant between 0 and 1.

[0035] Referring to the interruption in FIG. 2, the voltage (Vcc) of the clamp capacitor (Cc) included in the first switching circuit (21) and the output voltage (Vpa) of the first switching circuit (21) are shown. The phase of the voltage (Vcc) for the clamp capacitor (Cc) can be synchronized with the voltage of the AC side through synchronous rectification control.

[0036] Referring to the bottom of FIG. 2, a second duty command (Ds) is shown, which indicates the switching duty of the leg included in the second switching circuit (22) and the carrier wave for each of the switch elements (Q'1, Q'4) and switch elements (Q'2, Q'3) included in the second switching circuit (22).

[0037] The control unit (30) can adjust the phase of the carrier wave for switch elements (Q'1, Q'4) and switch elements (Q'2, Q'3) relative to the phase of the carrier wave for switch elements (Q1, Q4) and switch elements (Q2, Q3) by a phase shift angle (ф). Accordingly, the control unit (30) can control the active power component of the bidirectional charger (20) by adjusting the magnitude and direction of the current for the AC terminal. More specifically, when the charging mode is performed, the control unit (30) can set the polarity of the phase shift angle (ф) to positive and set the magnitude of the phase shift angle (ф) to be larger as the value of the active power command increases. Conversely, when the discharging mode is performed, the control unit (30) can set the polarity of the phase shift angle (ф) to negative and set the magnitude of the phase shift angle (ф) to be larger as the value of the active power command decreases.

[0038] Additionally, the control unit (30) can control the phase of the current relative to the voltage relative to the AC terminal by adjusting the phase of the second duty command (Ds) by the voltage-current phase angle (θ) according to the reactive power command. Accordingly, the control unit (30) can control the reactive power component of the bidirectional charger (20). More specifically, the control unit (30) can set the polarity of the voltage-current phase angle (θ) to positive according to the inductive reactive power command and set the polarity of the voltage-current phase angle (θ) to negative according to the capacitive reactive power command.

[0039] Meanwhile, if the phase of the second duty command (Ds) is adjusted by the voltage-current phase angle (θ) according to the reactive power command, the current to the AC terminal may have an unstable waveform as the polarity of the instantaneous power to the AC terminal changes due to the reactive power component.

[0040] In this embodiment, the control unit (30) can mitigate the instability of the current that occurs when adjusting the phase of the second duty command (Ds) based on the reactive power command by setting the polarity of the phase transition angle (ф) according to the active power command to be the same as the polarity of the instantaneous power for the AC terminal of the bidirectional charger (20).

[0041] More specifically, when the charging mode is performed, the control unit (30) sets the polarity of the phase shift angle (ф) to positive, but can invert the polarity of the phase shift angle (ф) to negative if the polarity of the instantaneous power for the AC terminal corresponds to negative. Additionally, when the discharge mode (V2L mode, V2G mode) is performed, the control unit (30) sets the polarity of the phase shift angle (ф) to negative, but can invert the polarity of the phase shift angle (ф) to positive if the polarity of the instantaneous power for the AC terminal corresponds to positive.

[0042] Below, we will examine in detail the configuration and operation method of each of the first controller (100) and the second controller (200) included in the control unit (30).

[0043] FIG. 3 is a block diagram illustrating the configuration of a first controller (100) that controls the execution of a charging mode and a V2G mode according to an embodiment of the present invention.

[0044] As illustrated in FIG. 3, the first controller (100) may include a current command generation unit (110), a sensing current conversion unit (120), a phase shift angle setting unit (130), a carrier generation unit (140), a voltage-current phase control unit (150), a phase detection unit (160), a first pulse width modulation control unit (170), and a second pulse width modulation control unit (180).

[0045] The first controller (100) can output a first switching signal (S1-S4) and a second switching signal (S'1-S'4) based on an active power command (Pac_ref), a reactive power command (Qac_ref), a sensing voltage (Vac_sen), and a sensing current (Iac_sen) when in charging mode or V2G mode.

[0046] The active power command (Pac_ref) and the reactive power command (Qac_ref) are applied from an external charging station connected to the grid power when the charging mode or V2G mode is performed, and the sensing voltage (Vac_sen) and the sensing current (Iac_sen) may be applied from a sensor (not shown) that detects the voltage and current of the AC terminals (A1, A2).

[0047] The first switching signal (S1-S4) is generated based on the first carrier wave (Cp) and the first duty command (Dp), and the second switching signal (S'1-S'4) can be generated based on the second carrier wave (Cs) and the second duty command (Ds).

[0048] Below, each component of the first controller (100) is described.

[0049] The current command generation unit (110) can generate an effective current command (Iac_d_ref) based on an effective power command (Pac_ref) and a sensing voltage (Vac_sen), and generate a reactive current command (Iac_q_ref) based on a reactive power command (Qac_ref) and a sensing voltage (Vac_sen).

[0050] The sensing current conversion unit (120) can perform a DQ transformation on the sensing current (Iac_sen) to output a sensing effective current (Iac_d_sen) and a sensing reactive current (Iac_q_sen). The DQ transformation may involve a Clarke transformation and a Park transformation performed sequentially.

[0051] The phase shift angle setting unit (130) may include an effective current control unit (131) and a selection unit (132). The phase shift angle setting unit (130) can control the effective power component of the bidirectional charger (20) by setting the phase shift angle (ф) so that the sensing effective current (Iac_d_sen) follows the effective current command (Iac_d_ref).

[0052] Additionally, the phase shift angle setting unit (130) can reverse the polarity of the phase shift angle (ф) based on the activated detection signal (det) when the polarity of the instantaneous power for the AC terminal becomes different due to the reactive power component (i.e., when the polarity of the instantaneous power corresponds to negative in charging mode or positive in discharging mode). That is, by setting the polarity of the phase shift angle (ф) to be the same as the polarity of the instantaneous power for the AC terminal, the phase shift angle setting unit (130) can mitigate the instability of the current that occurs when adjusting the phase of the second duty command (Ds) based on the reactive power command.

[0053] The active current control unit (131) sets a pre-phase shift angle (ф_raw) so that the sensing active current (Iac_d_sen) follows the active current command (Iac_d_ref), and can output an inverted phase shift angle (-ф_raw) by reversing the polarity of the set pre-phase shift angle (ф_raw). The polarity of the pre-phase shift angle (ф_raw) can be set to positive when the charging mode is performed and to negative when the V2G mode is performed.

[0054] The selection unit (132) can output either a pre-phase shift angle (ф_raw) or an inverted phase shift angle (-ф_raw) as a phase shift angle (ф) depending on whether the detection signal (det) is activated. More specifically, the selection unit (132) can output the pre-phase shift angle (ф_raw) as the phase shift angle (ф) when the detection signal (det) is deactivated, and output the inverted phase shift angle (-ф_raw) as the phase shift angle (ф) when the detection signal (det) is activated.

[0055] The carrier generation unit (140) can generate the first carrier wave (Cp) and the second carrier wave (Cs) at the same frequency and adjust the phase of the second carrier wave (Cs) relative to the phase of the first carrier wave (Cp) by a phase shift angle (ф).

[0056] The voltage-current phase control unit (150) may include a reactive current control unit (151), a DQ inverse converter (152), and an absolute value circuit (153). The voltage-current phase control unit (150) can control the reactive power component of the bidirectional charger (20) by adjusting the phase of the second duty command (Ds) so that the sensing reactive current (Iac_q_sen) follows the reactive current command (Iac_q_ref).

[0057] The reactive current control unit (151) can generate a quadrature axis duty command (Dq) so that the sensing reactive current (Iac_q_sen) follows the reactive current command (Iac_q_ref).

[0058] The DQ inverse transformation unit (152) can generate a pre-duty command (Ds_raw) by performing an inverse DQ transformation on the direct axis duty command (Dd) and the lateral axis duty command (Dq). The inverse DQ transformation may involve a Park inverse transformation and a Clarke inverse transformation performed sequentially. The value of the direct axis duty command (Dd) can be set to a constant between 0 and 1. The pre-duty command (Ds_raw) can represent the phase difference between the current of the AC side and the voltage of the AC side, regardless of the charging mode and the discharging mode.

[0059] The absolute value circuit (153) can receive a pre-duty command (Ds_raw) and generate a second duty command (Ds) having the absolute value of the pre-duty command (Ds_raw).

[0060] The phase detection unit (160) can generate a detection signal (det) to control the polarity of the phase transition angle (ф) to be the same as the polarity of the instantaneous power by comparing the polarity of the sensing voltage (Vac_sen) and the pre-duty command (Ds_raw).

[0061] More specifically, the phase detection unit (160) can disable the detection signal (det) when the polarity of the sensing voltage (Vac_sen) and the pre-duty command (Ds_raw) is the same (i.e., when the polarity of the instantaneous power for the AC terminal in charging mode corresponds to positive, or when the polarity of the instantaneous power for the AC terminal in discharging mode corresponds to negative). Accordingly, the selection unit (132) can output the pre-phase shift angle (ф_raw) as the phase shift angle (ф).

[0062] In contrast, the phase detection unit (160) can activate a detection signal (det) when the polarity of the sensing voltage (Vac_sen) and the pre-duty command (Ds_raw) differs due to a reactive power component (i.e., when the polarity of the instantaneous power for the AC terminal in charging mode corresponds to negative, or when the polarity of the instantaneous power for the AC terminal in discharging mode corresponds to positive). Accordingly, the selection unit (132) can output an inverted phase shift angle (-ф_raw) as a phase shift angle (ф).

[0063] The first pulse width modulation control unit (170) can determine the logic level of the first switching signal (S1-S4) based on the result of comparing the first carrier wave (Cp) and the first duty command (Dp).

[0064] The second pulse width modulation control unit (180) can determine the logic level of the second switching signal (S'1-S'4) based on the result of comparing the second carrier wave (Cs) and the second duty command (Ds).

[0065] FIGS. 4 and FIGS. 5 are waveforms of the current and voltage of a bidirectional charger (20) when a first controller (100) according to an embodiment of the present invention controls the active power component and the reactive power component. FIG. 4 corresponds to the case where a charging mode is performed, and FIG. 5 corresponds to the case where a V2G mode is performed.

[0066] Referring to FIG. 4, waveforms for the voltage (Vac) of the AC side, the current (Iac) of the AC side, and the current (Ibatt) of the battery (10) corresponding to each case where the first controller (100) according to the present embodiment controls only the active power component in charging mode (Power Factor = 1), controls the active power component and the inductive reactive power component (Lagging Power Factor = 0.9), and controls the active power component and the capacitive reactive power component (Leading Power Factor = 0.9) are shown.

[0067] Referring to FIG. 5, waveforms for the voltage (Vac), current (Iac), and current (Ibatt) of the AC terminal corresponding to the case where the first controller (100) according to the present embodiment controls only the active power component in V2G mode (Power Factor = -1), the case where it controls the active power component and the inductive reactive power component (Lagging Power Factor = -0.9), and the case where it controls the active power component and the capacitive reactive power component (Leading Power Factor = -0.9), respectively, are shown.

[0068] FIG. 6 is a circuit diagram according to one embodiment of the phase detection unit (160) illustrated in FIG. 3. As illustrated in FIG. 6, the phase detection unit (160) may include a first comparator (161), a second comparator (162), and an XOR gate (163).

[0069] The first comparator (161) and the second comparator (162) can compare the levels of the sensing voltage (Vac_sen) and the pre-duty command (Ds_raw) with the level of the ground voltage (Vss) to output comparison result signals (comp1, comp2). The comparison result signals (comp1, comp2) may have the same logic level if the polarities of the sensing voltage (Vac_sen) and the pre-duty command (Ds_raw) are the same. Conversely, the comparison result signals (comp1, comp2) may have different logic levels if the polarities of the sensing voltage (Vac_sen) and the pre-duty command (Ds_raw) are different.

[0070] When the logic levels of the comparison result signals (comp1, comp2) of the XOR gate (163) are the same, the detection signal (det) can be deactivated to a logic low level, and when the logic levels of the comparison result signals (comp1, comp2) are different, the detection signal (det) can be activated to a logic high level.

[0071] FIGS. 7 and FIGS. 8 are drawings for explaining the operation of the phase detection unit (160) shown in FIG. 3. FIG. 7 corresponds to the case where a charging mode is performed, and FIG. 8 corresponds to the case where a discharging mode is performed.

[0072] Referring to Figures 7 and 8, it can be seen that the pre-duty command (Ds_raw) represents the phase difference between the current (Iac) of the AC side and the voltage (Vac) of the AC side, regardless of the charging mode and the discharging mode.

[0073] Referring to Fig. 7, when the charging mode is performed, the prephase shift angle (ф_raw) corresponds to positive (+). It can be seen that the polarity of the phase shift angle (ф) is set to be the same as the prephase shift angle (ф_raw) when the polarity of the instantaneous power of the AC side corresponds to positive (+), but is set differently from the prephase shift angle (ф_raw) when the polarity of the instantaneous power of the AC side corresponds to negative (-).

[0074] Referring to Fig. 8, when the discharge mode is performed, the prephase shift angle (ф_raw) corresponds to negative (-). It can be seen that the polarity of the phase shift angle (ф) is set to be the same as the prephase shift angle (ф_raw) when the polarity of the instantaneous power of the AC side corresponds to negative (-), but is set differently from the prephase shift angle (ф_raw) when the polarity of the instantaneous power of the AC side corresponds to positive (+).

[0075] FIGS. 9 and FIGS. 10 are waveform diagrams illustrating the operation of reversing the polarity of the phase shift angle (ф) when controlling a reactive power component according to an embodiment of the present invention. FIG. 9 corresponds to the present embodiment in which the operation of reversing the polarity of the phase shift angle (ф) when controlling a reactive power component is performed, and FIG. 10 corresponds to a comparative example in which, unlike the present embodiment, the operation of reversing the polarity of the phase shift angle (ф) when controlling a reactive power component is not performed.

[0076] Referring to FIGS. 9 and 10, waveforms of the voltage (Vac), current (Iac), first duty command (Dp), second duty command (Ds), phase shift angle (ф), and voltage-current phase angle (θ) are shown when controlling the inductive reactive power component in discharge mode.

[0077] Referring to Fig. 9, when the polarity of the voltage (Vac) and current (Iac) of the AC side is the same (i.e., when the polarity of the instantaneous power corresponds to positive), it can be seen that the waveform of the current (Iac) of the AC side is stably generated as the polarity of the phase shift angle (ф) is reversed.

[0078] Referring to FIG. 10, unlike the present embodiment, when the polarity of the voltage (Vac) and current (Iac) of the AC side is the same, it can be seen that the waveform of the current (Iac) of the AC side becomes unstable when the polarity of the phase shift angle (ф) is maintained.

[0079] FIG. 11 is a block diagram illustrating the configuration of a second controller (200) that controls the execution of a V2L mode according to one embodiment of the present invention.

[0080] As illustrated in FIG. 11, the second controller (200) may include a phase-locked loop circuit (210), a phase shift angle setting unit (230), a carrier generation unit (240), a voltage-current phase control unit (250), a phase detection unit (260), a first pulse width modulation control unit (270), and a second pulse width modulation control unit (280).

[0081] The second controller (200) can output a first switching signal (S1-S4) and a second switching signal (S'1-S'4) based on an active voltage command (Vac_d_ref), a reactive voltage d command (Vac_q_ref), a frequency command (fac_ref), and a sensing voltage (Vac_sen) when in V2L mode.

[0082] When V2L mode is performed, the active voltage command (Vac_d_ref), the reactive voltage command (Vac_q_ref), and the frequency command (fac_ref) are applied from a higher controller (not shown) that controls the second controller (200), such as a vehicle controller (VCU) or a charging general controller (VCMS), and the sensing voltage (Vac_sen) may be applied from a sensor (not shown) that detects the voltage of the AC terminals (A1, A2).

[0083] The phase-locked loop circuit (210) can generate a sensing effective voltage (Vac_d_sen) and a sensing reactive voltage (Vac_q_sen) from a sensing voltage (Vac_sen) based on a frequency command (fac_ref).

[0084] The phase shift angle setting unit (230) may include an effective voltage control unit (231) and a selection unit (232). The operation method of the phase shift angle setting unit (230) is implemented in the same way as the operation method of the phase shift angle setting unit (130) shown in FIG. 3, and the effective voltage command (Vac_d_ref) corresponds to the effective current command (Iac_d_ref) of FIG. 3, and the sensing effective voltage (Vac_d_sen) corresponds to the sensing effective current (Iac_d_sen) of FIG. 3.

[0085] The voltage-current phase control unit (250) may include a reactive voltage control unit (251), a DQ inverse converter (252), and an absolute value circuit (253). The operation method of the voltage-current phase control unit (250) is implemented in the same way as the operation method of the voltage-current phase control unit (150) shown in FIG. 3, and the reactive voltage command (Vac_q_ref) corresponds to the reactive current command (Iac_q_ref) of FIG. 3, and the sensing reactive voltage (Vac_q_sen) corresponds to the sensing reactive current (Iac_q_sen) of FIG. 3.

[0086] Each of the carrier generation unit (240), voltage-current phase control unit (250), phase detection unit (260), first pulse width modulation control unit (270), and second pulse width modulation control unit (280) can be implemented in the same way as the carrier generation unit (140), voltage-current phase control unit (150), phase detection unit (160), first pulse width modulation control unit (170), and second pulse width modulation control unit (180) shown in FIG. 3.

[0087] FIG. 12 is a waveform of the current and voltage of a bidirectional charger (20) when a second controller (200) according to one embodiment of the present invention controls the active power component and the reactive power component in V2L mode.

[0088] Referring to FIG. 12, waveforms for the voltage (Vac), current (Iac), and current (Ibatt) of the AC terminal corresponding to each case where the second controller (200) according to the present embodiment controls only the active power component in V2L mode (Power Factor = -1), controls the active power component and the inductive reactive power component (inductive load) (Lagging Power Factor = -0.9), and controls the active power component and the capacitive reactive power component (capacitive load) (Leading Power Factor = -0.9) are shown.

[0089] Meanwhile, the present invention described above can be implemented as computer-readable code on a medium on which a program is recorded. A computer-readable medium includes all types of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable media include HDD (Hard Disk Drive), SSD (Solid State Disk), SSD (Silicon Disk Drive), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. Accordingly, the above detailed description should not be interpreted restrictively in all respects and should be considered exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included within the scope of the present invention. Explanation of the symbols

[0090] 10: Battery 20: Bidirectional charger 21: First switching circuit 22: Second switching circuit 23: Transformer 30: Control unit 100: 1st Controller 200: 2nd Controller

Claims

Claim 1 A battery charging device comprising: a bidirectional charger including a first switching circuit connected to an AC terminal, a second switching circuit connected to a battery, and a transformer connected between the first switching circuit and the second switching circuit; and a controller that switches a leg included in the first switching circuit based on a first carrier wave and a first duty command, and switches a leg included in the second switching circuit based on a second carrier wave and a second duty command, wherein the phase of the second carrier wave relative to the phase of the first carrier wave is adjusted by a phase shift angle according to an active power command, and the phase of the second duty command is adjusted according to a reactive power command. Claim 2 A battery charging device according to claim 1, wherein the active power command and the reactive power command are applied from an external device connected to the grid power source when a charging mode or a V2G (Vehicle to Grid) mode is performed. Claim 3 A battery charging device according to claim 1, wherein the controller sets the polarity of the phase transition angle to be the same as the polarity of the instantaneous power for the AC terminal. Claim 4 A battery charging device according to claim 3, wherein the controller sets the polarity of the phase shift angle to positive when a charging mode is performed, and reverses the polarity of the phase shift angle when the polarity of the instantaneous power corresponds to negative, and sets the polarity of the phase shift angle to negative when a discharging mode is performed, and reverses the polarity of the phase shift angle when the polarity of the instantaneous power corresponds to positive. Claim 5 A battery charging device according to claim 1, wherein the controller sets the magnitude of the phase transition angle larger as the value of the effective power command increases when a charging mode is performed, and sets the magnitude of the phase transition angle larger as the value of the effective power command decreases when a discharging mode is performed. Claim 6 A battery charging device according to claim 1, wherein the controller controls the magnitude and direction of the current for the AC terminal by adjusting the phase shift angle according to the effective power command. Claim 7 A battery charging device according to claim 1, wherein the controller controls the phase of the current relative to the phase of the voltage relative to the phase of the AC terminal by adjusting the phase of the second duty command by the voltage-current phase angle according to the reactive power command. Claim 8 A battery charging device according to claim 1, wherein the first duty command represents the switching duty of a leg included in the first switching circuit, and the second duty command represents the switching duty of a leg included in the second switching circuit, wherein the value of the first duty command is set as a constant. Claim 9 A battery charging device according to claim 1, wherein the controller comprises: a current command generating unit that generates an effective current command based on the effective power command and the sensing voltage of the AC unit, and generates a reactive current command based on the reactive power command and the sensing voltage; a phase shift angle setting unit that sets the phase shift angle so that the sensing effective current of the AC unit follows the effective current command; and a voltage-current phase control unit that adjusts the phase of the second duty command so that the sensing reactive current of the AC unit follows the reactive current command. Claim 10 A battery charging device according to claim 9, wherein the phase shift angle setting unit includes: an effective current control unit that sets a pre-phase shift angle so that the sensing effective current follows the effective current command and outputs an inverted phase shift angle by reversing the polarity of the set pre-phase shift angle; and a selection unit that outputs the pre-phase shift angle as the phase shift angle when the sensing signal is deactivated and outputs the inverted phase shift angle as the phase shift angle when the sensing signal is activated. Claim 11 A battery charging device according to claim 10, wherein the detection signal is activated when the polarity of the instantaneous power for the AC terminal corresponds to negative in charging mode or when the polarity of the instantaneous power corresponds to positive in discharging mode. Claim 12 In claim 10, the voltage-current phase control unit comprises: a reactive current control unit that generates a horizontal duty command such that the sensing reactive current of the AC section follows the reactive current command; a DQ inverse transform unit that generates a pre-duty command by performing a DQ inverse transform on the direct duty command and the horizontal duty command; and an absolute value circuit that receives the pre-duty command and generates the second duty command having the absolute value of the pre-duty command, wherein the controller further comprises a phase sensing unit that generates the sensing signal by comparing the polarity of the sensing voltage and the pre-duty command. Claim 13 A battery charging device according to claim 12, wherein the phase sensing unit deactivates the sensing signal when the polarity of the sensing voltage and the pre-duty command are the same, and activates the sensing signal when the polarity of the sensing voltage and the pre-duty command are different. Claim 14 A battery charging device according to claim 1, wherein the controller comprises: a carrier generation unit that generates the first carrier wave and the second carrier wave at the same frequency and adjusts the phase of the second carrier wave relative to the phase of the first carrier wave by the phase shift angle; a first pulse width modulation control unit that determines the logic level of a first switching signal for switching a leg included in the first switching circuit based on the result of comparing the first carrier wave and the first duty command; and a second pulse width modulation control unit that determines the logic level of a second switching signal for switching a leg included in the second switching circuit based on the result of comparing the second carrier wave and the second duty command. Claim 15 A battery charging device according to claim 1, wherein the first switching circuit comprises: a clamp capacitor; a first leg connected between both ends of the clamp capacitor and connected to one end of the primary coil of the transformer; a second leg connected between both ends of the clamp capacitor and connected to the other end of the primary coil of the transformer; and a third leg connected between both ends of the clamp capacitor. Claim 16 A battery charging device according to claim 1, wherein the second switching circuit comprises: a fourth leg connected between both ends of the battery and connected to one end of the secondary coil of the transformer; and a fifth leg connected between both ends of the battery and connected to the other end of the secondary coil of the transformer. Claim 17 A battery charging device comprising: a bidirectional charger including a first switching circuit connected to an AC terminal, a second switching circuit connected to a battery, and a transformer connected between the first switching circuit and the second switching circuit; and a controller that switches a leg included in the first switching circuit based on a first carrier wave and a first duty command, and switches a leg included in the second switching circuit based on a second carrier wave and a second duty command, wherein the phase of the second carrier wave relative to the phase of the first carrier wave is adjusted by a phase shift angle according to an effective voltage command, and the phase of the second duty command is adjusted according to an reactive voltage command. Claim 18 In claim 17, the battery charging device wherein the effective voltage command and the reactive voltage command are applied from a higher-level controller controlling the controller when the V2L (Vehicle to Load) mode is performed. Claim 19 In claim 17, the battery charging device, wherein the controller sets the polarity of the phase shift angle to be the same as the polarity of the instantaneous power for the AC terminal. Claim 20 A battery charging device according to claim 17, wherein the controller comprises: a phase-locked loop circuit that generates a sensing effective voltage and a sensing reactive voltage from a sensing voltage of the AC section based on a frequency command; a phase shift angle setting unit that sets the phase shift angle so that the sensing effective voltage of the AC section follows the effective voltage command; and a voltage-current phase control unit that adjusts the phase of the second duty command so that the sensing reactive voltage of the AC section follows the reactive voltage command.

Images