Method and apparatus for controlling phase command compensation of DAB converter

Abstract

The present invention relates to a method and an apparatus for controlling phase command compensation of a dual active bridge (DAB) converter, and more particularly, to a method and an apparatus for controlling phase command compensation of a DAB converter, in which a phase command of a leg of the DAB converter is corrected so as not to deviate from a range of a minimum value (0) to a maximum value (π) in controlling the phase of the leg of the DAB converter.

Description

Phase command compensation control method and control device of a DAB converter

[0001] The present invention relates to a method for controlling maximum value phase command compensation and a control device for a DAB converter.

[0002] Dual Active Bridge converters have advantages such as electrical isolation, high power density, a wide voltage regulation range, and soft switching, so they are widely used in electric vehicles and energy storage devices.

[0003] Figure 1 illustrates a typical DAB converter.

[0004] Referring to FIG. 1, the DAB converter consists of two full-bridge circuits (20, 50) separated by a transformer T1 (30) and an inductor (L1). All switches (Q1 to Q8) of each leg (21, 22, 51, 52) of the full-bridge circuits (20, 50) are controlled by a phase modulation method in which they operate with a PWM signal having a duty cycle of 50% and phases shifted relative to each other. The greater the phase difference between the primary and secondary full-bridge circuits (20, 50), the greater the amount of power passing through the DAB converter.

[0005] However, during the control process, the phase command of each leg may deviate from the range of minimum value (0) to maximum value (ð). When the phase command deviates from the range of minimum value (0) to maximum value (ð), a larger phase command is required to reach the target power, and as a result, the control of the DAB converter becomes saturated, which may cause an abnormality in the output.

[0006] Therefore, it is necessary to develop a phase command algorithm that controls the phase command so that it does not exceed the range of a minimum value (0) to a maximum value (ð). The present invention proposes a control method that enables the control of a DAB converter to reach a target power without becoming saturated.

[0007] The technical problem that the present invention aims to solve is to provide a control method that allows the control of a DAB converter to reach a target power without the control becoming saturated, by controlling the phase command so that it does not exceed the range of a minimum value to a maximum value.

[0008] The technical problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below.

[0009] The phase command compensation control method of the present invention for solving the above technical problem is a control method of a control device that controls the phase of a leg of a dual active bridge (DAB) converter, and can correct the phase command of the leg so that it does not go outside the range of a minimum value (0) to a maximum value (π).

[0010] In some embodiments of the present invention, when the basic phase command of the DAB converter is Φf, the reference phase command of the first bridge circuit of the DAB converter is Φp = 0.5π - 0.5Φf, and the reference phase command of the second bridge circuit of the DAB converter may be Φs = 0.5π + 0.5Φf.

[0011] In some embodiments of the present invention, if the phase command Φ1 of the leading leg of the primary bridge circuit of the DAB converter is less than 0, an offset value of -Φ1 is added.

[0012] In some embodiments of the present invention, if the phase command Φ3 of the leading leg of the secondary bridge circuit of the DAB converter is less than 0, an offset value of -Φ3 is added.

[0013] In some embodiments of the present invention, if the phase command Φ2 of the lagging leg of the primary bridge circuit of the DAB converter is greater than π, an offset value of π-Φ2 may be added.

[0014] In some embodiments of the present invention, if the phase command Φ4 of the lagging leg of the secondary bridge circuit of the DAB converter is greater than π, an offset value of π-Φ4 may be added.

[0015] The phase command control device of the DAB converter of the present invention for solving the above technical problem includes a basic phase calculation unit, a phase difference calculation unit, a phase calculation unit per leg, and a PWM generation unit per leg, and can correct the phase command of the leg so that it does not exceed the range of a minimum value (0) to a maximum value (π).

[0016] In some embodiments of the present invention, the phase difference calculation unit can calculate that when the basic phase command of the DAB converter is Φf, the reference phase command of the first bridge circuit of the DAB converter is Φp = 0.5π - 0.5Φf, and the reference phase command of the second bridge circuit of the DAB converter is Φs = 0.5π + 0.5Φf.

[0017] In some embodiments of the present invention, the leg-specific phase calculation unit may add an offset value of -Φ1 if the phase command Φ1 of the leading leg of the primary bridge circuit of the DAB converter is less than 0.

[0018] In some embodiments of the present invention, the leg-specific phase calculation unit may add an offset value of -Φ3 if the phase command Φ3 of the leading leg of the secondary bridge circuit of the DAB converter is less than 0.

[0019] In some embodiments of the present invention, the leg-specific phase calculation unit may add an offset value of π-Φ2 if the phase command Φ2 of the lagging leg of the primary bridge circuit of the DAB converter is greater than π.

[0020] In some embodiments of the present invention, the leg-specific phase calculation unit may add an offset value of π-Φ4 if the phase command Φ4 of the lagging leg of the secondary bridge circuit of the DAB converter is greater than π.

[0021] According to the phase command compensation control method of the DAB converter of the present invention, the phase command is controlled so as not to exceed the range of minimum to maximum values, thereby enabling the control of the DAB converter to reach the target power without becoming saturated, which enables stable operation of the DAB converter.

[0022] Therefore, stable charging and discharging of batteries in electric vehicles and energy storage systems (ESS) to which DAB converters are applied becomes possible.

[0023] Figure 1 illustrates a typical DAB converter.

[0024] FIG. 2 illustrates a control device according to one embodiment of the present invention.

[0025] FIG. 3 illustrates a phase command for each leg according to an embodiment of the present invention.

[0026] FIG. 4 is a diagram illustrating the compensation of a phase command according to an embodiment of the present invention.

[0027] FIG. 5 is intended to exemplarily explain the compensation effect of a phase command according to the present invention.

[0028] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0029] "And / or" includes each of the mentioned items and all combinations of one or more.

[0030] The terms used herein are for describing embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprising" and / or "comprising" does not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0031] Furthermore, throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly" or "electrically connected" with other members or elements in between.

[0032] Additionally, throughout the specification, the description that each layer (film), region, pattern, or structure is formed "on" or "under" the substrate, each layer (film), region, pad, or pattern includes both direct formation and formation through another layer. The criteria for "on" or "under" each layer are described based on the drawings.

[0033] Furthermore, expressions such as 'first, second,' etc., are used solely to distinguish multiple compositions and do not limit the order or other characteristics between the compositions.

[0034] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0035] Hereinafter, a phase command compensation control method for a DAB converter according to the present invention will be described with reference to the drawings.

[0036] FIG. 1 illustrates a general DAB converter, and FIG. 2 illustrates a control device according to an embodiment of the present invention.

[0037] Referring to FIGS. 1 and 2, the DAB converter consists of two full-bridge circuits (20, 50) separated by a transformer T1 (30) and an inductor (L1). Control of all switches (Q1 to Q8) of each leg (21, 22, 51, 52) of the full-bridge circuits (20, 50) is achieved by a phase modulation method in which the PWM signal has a duty cycle of 50% and is phase-shifted relative to the other. The greater the phase difference between the primary and secondary full-bridge circuits (20, 50), the greater the amount of power passing through the DAB converter.

[0038] Referring to FIG. 1, the DAB converter includes a voltage source (10), a primary bridge circuit (20), an inductor (L1), a transformer T1 (30), and a secondary bridge circuit (50).

[0039] The first bridge circuit (20) is composed of a first leading leg (21) including switches Q1 and Q2 and a first lagging leg (22) including switches Q3 and Q4, and the second bridge circuit (50) is composed of a second leading leg (51) including switches Q5 and Q6 and a second lagging leg (52) including switches Q7 and Q8.

[0040] Referring to FIG. 2, the control device (90) of the DAB converter according to the present invention is operated by including a basic phase calculation unit (91), a phase difference calculation unit (92), a leg-specific phase calculation unit (93), and a leg-specific PWM generation unit (94).

[0041] The above control device (90) may be configured to include a microcontroller, a memory, and peripheral circuits, and the memory stores a program including an algorithm of the phase command compensation method according to the present invention, and the phase command compensation method according to the present invention may be performed by a microcontroller that executes the program.

[0042] The basic phase calculation unit (91) calculates a basic phase (Φf) command under the conditions of power (P), voltage (V), and current (I) given as control targets, and the phase difference calculation unit (92) can calculate αp (phase command difference between the primary leading leg and the lagging leg) and αs (phase command difference between the secondary leading leg and the lagging leg) using the calculated basic phase (Φf) command, input voltage (Vin), and output voltage (Vo). Here, αp = |Φ1 - Φ2| and αs = |Φ3 - Φ4|.

[0043] The leg-specific phase calculation unit (93) calculates the phase commands (Φ1, Φ2, Φ3, Φ4) ​​of each leg using αp (phase command difference between the primary leading leg and the lagging leg) and αs (phase command difference between the secondary leading leg and the lagging leg) and the basic phase (Φf).

[0044] The leg-specific PWM generator (94) can generate a PWM driving waveform that operates switches (Q1 to Q8) using phase commands (Φ1, Φ2, Φ3, Φ4) ​​of each leg.

[0045] FIG. 3 illustrates phase commands for each leg according to an embodiment of the present invention, where (a) represents the case where the fundamental phase (Φf) is greater than 0, and (b) represents the case where the fundamental phase (Φf) is less than 0.

[0046] Referring to FIG. 2 and FIG. 3, the control device (90) of the DAB converter according to the present invention can calculate phase commands (Φ1, Φ2, Φ3, Φ4) ​​for each leg of the DAB converter as follows, using αp (phase command difference between the primary leading leg and the lagging leg), αs (phase command difference between the secondary leading leg and the lagging leg), and the basic phase (Φf), so that control of the input voltage (Vin) and output voltage (Vo) can be achieved in real time.

[0047] The basic phase calculation unit (91) can calculate a basic phase (Φf) command under the conditions of power (P), voltage (V), and current (I) given as a control target, and can calculate a reference phase command (Φp) of the first bridge circuit (20) and a reference phase command (Φs) of the second bridge circuit (50).

[0048] Since the basic phase (Φf) is Φf = Φs - Φp, the reference phase command Φp of the first bridge circuit (20) can be 0.5π - 0.5Φf, and the reference phase command Φs of the second bridge circuit (50) can be 0.5π + 0.5Φf.

[0049] In this way, it is desirable for Φp and Φs to vary according to Φf based on 0.5π.

[0050] This is because, since Φf = Φs-Φp, when Φf > 0, Φp must be smaller than the reference point 0.5π to satisfy Φ4 ≤ π. For example, if Φp is fixed at 0.5π and αs > 0 (input voltage Vin < output voltage Vo), then Φ4 > π.

[0051] In addition, since Φf = Φs - Φp, when Φf > 0, Φs must be greater than the reference point 0.5π to satisfy Φ1 < 0. For example, if Φs = 0.5π is fixed and αp > 0 (input voltage Vin > output voltage Vo), then Φ1 > 0.

[0052] The phase difference calculation unit (92) can calculate αp (phase command difference between the primary leading leg and the lagging leg) and αs (phase command difference between the secondary leading leg and the lagging leg) using the calculated basic phase (Φf) command, the input voltage (Vin), and the output voltage (Vo). Here, αp = |Φ1 - Φ2| and αs = |Φ3 - Φ4|.

[0053] The leg-specific phase calculation unit (93) calculates the phase commands (Φ1, Φ2, Φ3, Φ4) ​​of each leg using αp (phase command difference between the primary leading leg and the lagging leg) and αs (phase command difference between the secondary leading leg and the lagging leg) and the basic phase (Φf).

[0054] Since αp=|Φ1 - Φ2| and αs=|Φ3 - Φ4|, the phase commands (Φ1, Φ2, Φ3, Φ4) ​​of each leg are as follows.

[0055] Φ1 = Φp - 0.5αp

[0056] Φ2 = Φp + 0.5αp

[0057] Φ3 = Φs - 0.5αs

[0058] Φ4 = Φs + 0.5αs

[0059] Since Φp = 0.5π - 0.5Φf and Φs = 0.5π + 0.5Φf, the phase commands (Φ1, Φ2, Φ3, Φ4) ​​for each leg are as follows.

[0060] Φ1 = 0.5π - 0.5Φf - 0.5αp

[0061] Φ2 = Φ1 + αp

[0062] Φ3=Φ1 + Φf + 0.5αp - 0.5αs

[0063] Φ4=Φ1 + Φf + 0.5αp + 0.5αs

[0064] However, if the difference between the input voltage (Vin) and the output voltage (Vo) of the DAB converter is large, the phase command of each leg calculated as above may be outside the range of minimum value (0) to maximum value (π), so the phase calculation unit (93) for each leg can be corrected as follows.

[0065] FIG. 4 is a diagram illustrating the compensation of a phase command according to the present invention.

[0066] Referring to Fig. 4, an offset value can be added to the phase command of each leg of the DAB converter to compensate so that the phase command is within the range of the maximum and minimum values.

[0067] First, if the phase command Φ1 of the leading leg of the first-order bridge circuit is less than 0, an offset value of -Φ1 can be added. This can be expressed as follows.

[0068] Φ1 (= 0.5π - 0.5Φf - 0.5αp) + Φ offset → Φ1, where Φ offset = -Φ1.

[0069] If the phase command Φ3 of the leading leg of the next secondary bridge circuit is less than 0, an offset value of -Φ3 can be added. This can be expressed as follows.

[0070] Φ3 (= Φ1 + Φf + 0.5αp - 0.5αs) + Φ offset → Φ3, where Φ offset = -Φ3.

[0071] If the phase command Φ2 of the lagging leg of the following first-order bridge circuit is greater than π, an offset value of π - Φ2 can be added. This can be expressed as follows.

[0072] Φ2 (= Φ1 + αp) + Φ offset → Φ2, where Φ offset = π - Φ2.

[0073] If the phase command Φ4 of the lagging leg of the following second-order bridge circuit is greater than π, an offset value of π - Φ4 can be added. This can be expressed as follows.

[0074] Φ4 (= Φ1 + Φf + 0.5αp + 0.5αs) + Φ offset → Φ4, where Φ offset = π - Φ4.

[0075] At this time, since Φ1 and Φ3 are not less than 0, and Φ2 and Φ4 are not greater than π, no additional correction value is introduced.

[0076] The effect of the phase command with the offset value added in this way can be verified as follows.

[0077] FIG. 5 is intended to exemplarily explain the compensation effect of a phase command according to the present invention, where (a) shows the state before compensation and (b) shows the state after compensation.

[0078] Referring to Fig. 5, Φ2 is greater than π before compensation, but after compensation, Φ2 becomes equal to π, so the case where it becomes greater than π can be prevented.

[0079] As such, according to the phase command compensation method of the present invention, the phase command is controlled so as not to exceed the range of minimum to maximum values, thereby enabling the control of the DAB converter to reach the target power without becoming saturated.

[0080] Although the present invention has been described above, those skilled in the art will recognize that the invention may be implemented in other forms while maintaining the technical concept and essential features of the invention.

[0081] The scope of the present invention shall be defined by the claims, but all modifications or variations derived from configurations directly derived from the descriptions in the claims, as well as configurations equivalent thereto, shall be interpreted as being included within the scope of the present invention.

Claims

1. A control method for a control device that controls the phase of a leg of a dual active bridge (DAB) converter, A phase command compensation control method for a DAB converter that corrects the phase command of the above leg so that it does not exceed the range of a minimum value (0) to a maximum value (π).

2. In Paragraph 1, A phase command compensation control method for a DAB converter, wherein when the basic phase command of the DAB converter is Φf, the reference phase command of the first bridge circuit of the DAB converter is Φp = 0.5π - 0.5Φf, and the reference phase command of the second bridge circuit of the DAB converter is Φs = 0.5π + 0.5Φf.

3. In Paragraph 1, If the phase command Φ1 of the leading leg of the primary bridge circuit of the above DAB converter is less than 0, an offset value of -Φ1 is added, and A phase command compensation control method for a DAB converter, characterized by adding an offset value of -Φ3 when the phase command Φ3 of the leading leg of the secondary bridge circuit of the DAB converter is less than 0.

4. In Paragraph 1, If the phase command Φ2 of the lagging leg of the primary bridge circuit of the above DAB converter is greater than π, an offset value of π-Φ2 is added, and A phase command compensation control method for a DAB converter, characterized by adding an offset value of π-Φ4 when the phase command Φ4 of the lagging leg of the secondary bridge circuit of the DAB converter is greater than π.

5. A control device for controlling the phase of a leg of a dual active bridge (DAB) converter, A phase command control device for a DAB converter comprising a basic phase calculation unit, a phase difference calculation unit, a phase calculation unit per leg, and a PWM generation unit per leg, and correcting the phase command of the leg so that it does not exceed the range of a minimum value (0) to a maximum value (π).

6. In Paragraph 5, The above basic phase operation unit is, When the basic phase command of the DAB converter is Φf, the reference phase command of the first-order bridge circuit of the DAB converter is Φp = 0.5π - 0.5Φf, and A phase command control device for a DAB converter, wherein the reference phase command of the secondary bridge circuit of the DAB converter is calculated as Φs = 0.5π + 0.5Φf.

7. In Paragraph 5, The above-mentioned leg-specific phase calculation unit is, If the phase command Φ1 of the leading leg of the primary bridge circuit of the above DAB converter is less than 0, an offset value of -Φ1 is added, and A phase command control device for a DAB converter that adds an offset value of -Φ3 when the phase command Φ3 of the leading leg of the secondary bridge circuit of the DAB converter is less than 0.

8. In Paragraph 5, The above-mentioned leg-specific phase calculation unit is, If the phase command Φ2 of the lagging leg of the primary bridge circuit of the above DAB converter is greater than π, an offset value of π-Φ2 is added, and A phase command control device for a DAB converter that adds an offset value of π-Φ4 when the phase command Φ4 of the lagging leg of the secondary bridge circuit of the DAB converter is greater than π.

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