Method for synchronizing triangular wave signal

Abstract

The present invention relates to a method for synchronizing the phase of a triangular wave signal with the phase of a reference triangular wave. According to the present invention, the method for synchronizing the phase comprises the steps of: determining whether the period of a triangular wave signal is the same as the period of a reference triangular wave signal; adjusting the period of the triangular wave signal to be the same as the period of the reference triangular wave signal when the period of the triangular wave signal is not the same as the period of the reference triangular wave signal; determining whether a circulating current is generated after adjusting the period; and adjusting the maximum value of the triangular wave signal when the circulating current is generated.

Description

Synchronization method for triangular wave signals

[0001] The present invention relates to a method for synchronizing a triangular wave signal, and more particularly to a method for synchronizing a triangular wave signal with a reference triangular wave signal.

[0002] With the recent rise in interest and demand for eco-friendly ships, attempts are being made to install high-performance electrical equipment on vessels, driven by the rapid development of such devices.

[0003] Eco-friendly ships require high-capacity power converters. Power converters convert power from medium and high-power electronic distribution buses and grids.

[0004] Power converters may be equipped with Power Electronics Building Blocks (PEBBs) as a major component. These PEBBs are structural and functional elements of the power converter.

[0005] PEBB is a modular and expandable power converter that transforms any input power into a desired voltage, current, and frequency output.

[0006] PEBB can convert high voltage to a relatively lower voltage, convert low voltage to a relatively higher voltage, convert the frequency of electric alternating current to a different frequency, or convert direct current to alternating current and alternating current to direct current.

[0007] The upper controller controlling the PEBB compares a command value in the form of a sine wave with a triangular wave of a specific frequency to generate an on / off signal and transmits it to the PEBB. Accordingly, the PEBB applies the received signal to a switching element and uses it as a PWM signal.

[0008] Since ships and similar vessels require high-capacity power converters, multiple PEBBs are operated in parallel. In the parallel operation of PEBBs, synchronized operation with a reference triangular wave is essential.

[0009] However, even after synchronization is achieved, a problem may occur in the PWM mechanism where the PEBBs lose synchronization due to minute differences in triangular waves. In this case, since the PEBBs operate in parallel, if they fail to synchronize, a circulating current is generated between the parallel-connected PEBBs.

[0010] Conventionally, registered patent No. 10-0994612 discloses a technology for synchronizing the phase of a triangular wave signal, and registered patents No. 10-2169390 and No. 10-2524185 disclose waveform synchronization techniques for reducing or eliminating circulating current.

[0011] The present invention aims to provide a method for synchronizing a triangular wave signal with a reference triangular wave signal output from a higher-level controller.

[0012] The present invention aims to provide a method for synchronizing a triangular wave signal to prevent the generation of circulating current by synchronizing the period of the triangular wave signal to match the period of a reference triangular wave signal.

[0013] The present invention aims to provide a method for synchronizing a triangular wave signal, wherein if a circulating current occurs even after the period of the triangular wave signal is synchronized with the period of a reference triangular wave signal, the maximum value of the triangular wave signal is adjusted to eliminate the circulating current.

[0014] The present invention aims to provide a method for synchronizing a triangular wave signal by aligning the zero point of the triangular wave signal with the zero point of a reference triangular wave signal.

[0015] A method for synchronizing a triangular wave signal according to an embodiment of the present invention comprises: a step of determining whether the period of a triangular wave signal is the same as the period of a reference triangular wave signal; a step of adjusting the period of the triangular wave signal to be the same as the period of the reference triangular wave signal if they are not the same; a step of determining whether a circulating current occurs after adjusting the period; and a step of adjusting the maximum value of the triangular wave signal if the circulating current occurs.

[0016] In the present invention, the step of adjusting the maximum value includes the step of adjusting the maximum value upward or downward in a direction in which the circulating current is reduced.

[0017] In the present invention, the step of adjusting the maximum value adjusts the maximum value upward or downward until the circulating current is eliminated.

[0018] In the present invention, after the step of adjusting the maximum value, the method further includes the step of aligning the zero point of the triangular wave signal with the zero point of the reference triangular wave signal.

[0019] In the present invention, the step of matching the zero point involves adjusting the triangular wave signal so that the zero point of the triangular wave signal becomes equal to the zero point of the reference triangular wave signal.

[0020] In the present invention, after the step of determining whether the period of the triangular wave signal is the same as the period of the reference triangular wave signal or the step of adjusting the period of the triangular wave signal to be the same as the period of the reference triangular wave signal, the method further includes the step of monitoring in real time whether the circulating current is generated using a current sensor.

[0021] According to the method for synchronizing a triangular wave signal according to an embodiment of the present invention, the triangular wave signal of a power converter operating in parallel can be rapidly synchronized with a reference triangular wave signal, and the problem of circulating current occurring between power converters when a plurality of power converters are operated in parallel can be resolved.

[0022] FIG. 1 is an exemplary diagram of a power system installed on an eco-friendly ship according to an embodiment of the present invention.

[0023] FIG. 2 is an exemplary configuration diagram of a power converter according to an embodiment of the present invention.

[0024] FIG. 3 is a configuration diagram showing the connection relationship with the control unit of a PEBB according to an embodiment of the present invention.

[0025] FIG. 4 is a diagram illustrating the process of synchronizing a triangular wave signal with a reference triangular wave signal output from a higher-level controller according to an embodiment of the present invention.

[0026] FIG. 5 is a diagram illustrating the process of synchronizing a triangular wave signal with a reference triangular wave signal output from a higher-level controller according to another embodiment of the present invention.

[0027] Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the embodiments of the present invention, if it is determined that a detailed description of related known components or functions would hinder understanding of the embodiments of the present invention, such detailed description is omitted.

[0028] A power converter according to the present invention receives a reference triangular wave signal from a higher-level controller, and the power converter generates a triangular wave signal synchronized with the received reference triangular wave signal. At this time, the present invention provides a method for synchronizing the triangular wave signal generated by the power converter with the reference triangular wave signal. The power converter is a device that converts voltage, current, frequency, etc. The power converter generates a triangular wave signal synchronized with the reference triangular wave signal received from the higher-level controller and uses it as a switching signal for an internal switching element.

[0029] Throughout this specification, a method for synchronizing a triangular wave signal will be specifically described using a Power Electronics Building Block (PEBB) as an example of a power converter. A PEBB can constitute a power converter used in eco-friendly ships. Of course, it should be clearly stated that the triangular wave synchronization method of the present invention can be applied not only to PEBBs but also to all power converters that use a triangular wave signal as a switching signal.

[0030] FIG. 1 is an exemplary diagram of a mounted power system according to one embodiment of the present invention.

[0031] Referring to FIG. 1, a power system according to an embodiment of the present invention can be installed in an aircraft or an eco-friendly ship (1), etc.

[0032] The power system equipped in the ship (1) may be configured to include a power converter (10), a power generation facility (20), a load (50), and an energy storage device (40).

[0033] The power converter (10) can convert power generated from the power generation facility (20) by a predetermined process and supply it to a load (30) and / or an energy storage device (40).

[0034] The power converter (10) can distribute or control the entire power flow of the power system of the ship (1).

[0035] The power generation facility (20) is a facility that produces electricity and may include, for example, an electric generator, an engine generator, a solar power generation facility, a wind power generation facility, a hydroelectric power generation facility, etc.

[0036] The load (30) may include loads necessary to operate the vessel (1). In this embodiment, the load (30) may include, for example, a motor.

[0037] FIG. 2 is an exemplary configuration diagram of a power converter according to an embodiment of the present invention.

[0038] Referring to FIG. 2, a power converter (10) according to one embodiment of the present invention may include a plurality of PEBBs (100) and an upper controller (200) that controls each PEBB (100).

[0039] The power converter (10) is installed on a ship (1) and can convert and distribute any power into desired power using multiple PEBBs (100).

[0040] PEBB (100) is utilized as part of a power converter (10) and can perform the role of boosting or lowering the voltage according to the command of the upper controller (200), converting AC current to DC current or DC current to AC current, or distributing power to the load (30) by converting the frequency of the electrical signal.

[0041] PEBB (100) is a structural and functional component of the power converter (10) and is configured modularly to be expandable, and can convert any input power into a desired voltage, current, and frequency output according to the command of the upper controller (200).

[0042] In this embodiment, a plurality of PEBBs (100) are operated in parallel with each other. Each PEBB (100) can output the required torque according to the command of the upper controller (200).

[0043] The upper controller (200) can transmit the same reference triangular wave to each PEBB (100).

[0044] PEBB (100) can use a triangular wave signal synchronized with a reference triangular wave by using an internal signal generator (not shown) to generate a triangular wave signal and apply it to an internal switching element, thereby using the triangular wave signal as a switching signal.

[0045] The signal generator may be, for example, an oscillator. However, the present invention is not limited thereto, and any device capable of generating a triangular wave signal is applicable.

[0046] The triangular wave signal of PEBB (100) is basically generated in synchronization with the reference triangular wave signal. However, as time passes, a problem arises where it is not synchronized with the reference triangular wave signal due to minute changes in the triangular wave signal.

[0047] As such, if the PEBB triangular wave signal is not synchronized with the reference triangular wave signal, a problem arises where circulating current occurs between adjacent PEBBs when multiple PEBBs are operated in parallel. Therefore, it is important to quickly synchronize the PEBB triangular wave signal with the reference triangular wave signal.

[0048] Accordingly, the present invention provides a method for synchronizing the triangular wave signal of the PEBB (100) with the reference triangular wave signal output from the upper controller (200).

[0049] FIG. 3 is a configuration diagram showing the connection relationship between the control unit constituting the PEBB according to an embodiment of the present invention.

[0050] Referring to FIG. 3, a PEBB (100) according to an embodiment of the present invention may include a signal generation unit (101), a control unit (102), and an output unit (103).

[0051] The signal generation unit (101) receives a reference triangular wave signal output from the upper controller (200) and can generate a triangular wave signal synchronized with the received reference triangular wave signal.

[0052] The control unit (102) can control the overall operation of the PEBB (100).

[0053] The control unit (102) can control the triangular wave signal generated by the signal generation unit (101) to be output through the output unit (103).

[0054] The output unit (103) can output a triangular wave signal to an internal switching element (not shown) under the control of the control unit (102). Accordingly, the switching element can perform a switching operation using the triangular wave signal, thereby performing a conversion of voltage, current, frequency, etc. as described above.

[0055] The control unit (102) can check in real time whether synchronization between the reference triangular wave signal and the triangular wave signal is continuously being maintained.

[0056] The control unit (102) can synchronize the triangular wave signal with the reference triangular wave signal in a predetermined way if the triangular wave signal is not synchronized with the reference triangular wave signal.

[0057] Hereinafter, a method for synchronizing a triangular wave signal with a reference triangular wave signal according to an embodiment of the present invention is described in detail.

[0058] The triangular wave signal synchronization method according to the present invention prevents the generation of circulating current between adjacent PEBBs by synchronizing the triangular wave signals of the PEBBs with a reference triangular wave signal transmitted from an upper controller when a plurality of PEBBs are operated in parallel.

[0059] FIG. 4 is a diagram illustrating the process of synchronizing a triangular wave signal according to an embodiment of the present invention with a reference triangular wave signal output from a higher-level controller.

[0060] In FIG. 4 (a), a reference triangular wave signal (301) having a constant period (P) is shown, and in FIG. 4 (b), a PEBB triangular wave signal (302) slower than the reference triangular wave signal (301) with a constant period (P') is shown.

[0061] In the drawing, to distinguish between the two signals (301, 302), the reference triangular wave signal is indicated as 301 and the PEBB triangular wave signal is indicated as 302 in blue.

[0062] When operating multiple PEBBs (100) in parallel, the upper controller (200) transmits a reference triangular wave signal (301) having a set period (P) to each PEBB (100) for signal synchronization between PEBBs (100).

[0063] Each PEBB (100) synchronizes its PEBB triangular wave signal with this reference triangular wave signal (301) so that circulating current does not occur between multiple PEBBs (100) operating in parallel.

[0064] Referring to Figure 4(b), the process of synchronizing the PEBB triangular wave signal (302) with the reference triangular wave signal (301) is explained.

[0065] In the t11 section, when the PEBB (100) is operated for a long time, the PEBB triangular wave signal (302) may become out of sync with the reference triangular wave signal (301) due to minute changes inside the PEBB (100).

[0066] Specifically, in the t11 interval, an example is illustrated in which the period (P') of the PEBB triangular wave signal (302) becomes longer than the period (P) of the reference triangular wave signal (301). That is, an example is illustrated in which the period (P') of the PEBB triangular wave signal (302) is longer than the period (P) of the reference triangular wave signal (301) by +△P.

[0067] PEBB (100) can monitor the period (P') of its PEBB triangular wave signal (302) at a preset period or in real time to check if it is the same as the period (P) of the reference triangular wave signal (301).

[0068] As in the t11 interval, if the period (P') of the PEBB triangular wave signal (302) is different from the period (P) of the reference triangular wave signal (301), the PEBB (100) adjusts the PEBB triangular wave signal (302) so that the two periods become the same. That is, as in the t12 interval, the period (P') of the PEBB triangular wave signal (302) is synchronized with the period of the reference triangular wave signal (301). This can be called 'first-order synchronization'.

[0069] Specifically, in the first synchronization of the t12 interval, the existing PEBB triangular wave signal (302') indicated by the dotted line is adjusted to the new PEBB triangular wave signal (302) indicated by the solid line (adjusted from 302' to 302), thereby making the period (P') of the PEBB triangular wave signal (302) equal to the period (P) of the reference triangular wave signal (301).

[0070] Afterward, it is checked whether a circulating current is generated in multiple PEBBs (100) operating in parallel. This circulating current can be detected through a current sensor (not shown) provided inside the PEBB (100).

[0071] When a circulating current occurs, the maximum value (Max) of the PEBB triangular wave signal (302) is adjusted in the t13 interval.

[0072] When a circulating current occurs between PEBBs (100), the maximum value (Max) of the PEBB triangular wave signal (302) at t13 is adjusted upward or downward. This can be called 'secondary synchronization'. Adjusting the maximum value upward means raising or increasing the maximum value, and adjusting the maximum value downward means lowering or decreasing the maximum value.

[0073] At this time, in the second synchronization, the upward or downward adjustment of the maximum value (Max) must be adjusted in a direction that reduces the circulating current. For example, if the circulating current is reduced by adjusting the maximum value (Max) upward, it must be adjusted upward, and conversely, if the circulating current is reduced by adjusting it downward, it must be adjusted downward. In addition, the maximum value (Max) may be adjusted upward or downward in a direction that reduces the circulating current, and may be adjusted until no circulating current occurs.

[0074] In the t13 section, an example is shown in which the maximum value is adjusted upward from Max1 to Max2. That is, in the t13 section, the existing PEBB triangular wave signal (302') indicated by the dotted line is adjusted to the new PEBB triangular wave signal (302) indicated by the solid line (adjusted from 302' to 302), thereby eliminating the circulating current.

[0075] In this way, the periods of the two signals (301, 302) are synchronized in the first synchronization, and after the circulating current is eliminated by adjusting the maximum value (Max) of the PEBB triangular wave signal (302) upward or downward in the second synchronization, the zero point of the PEBB triangular wave signal (302) is matched with the zero point of the reference triangular wave signal (301).

[0076] Specifically, in the t14 interval, the zero point of the PEBB triangular wave signal (302) is aligned with the zero point (t0) of the reference triangular wave signal (301). This can be called 'third-order synchronization'. In third-order synchronization, the alignment of the zero points of the two signals is such that the zero point of the PEBB triangular wave signal (302) becomes equal to the reference triangular wave signal (301).

[0077] Here, the above zero point may refer to the point where the signal reaches its lowest point.

[0078] FIG. 5 is a diagram illustrating the process of synchronizing a triangular wave signal with a reference triangular wave signal output from a higher-level controller according to another embodiment of the present invention.

[0079] In FIG. 5(a), a reference triangular wave signal (301) having a constant period (P) is shown, and in FIG. 5(b), a PEBB triangular wave signal (302) faster than the reference triangular wave signal (301) with a constant period (P') is shown.

[0080] Unlike in Fig. 4, in Fig. 5, to distinguish between the two signals (301, 302), the reference triangular wave signal is indicated as 301 and the PEBB triangular wave signal is indicated as 302.

[0081] The PEBB (100) synchronizes its PEBB triangular wave signal (302) with the reference triangular wave signal (301) so that multiple PEBBs (100) operating in parallel do not generate circulating current between each other.

[0082] Referring to Fig. 5(b), the process of synchronizing the PEBB triangular wave signal (302) with the reference triangular wave signal (301) is explained.

[0083] In the t21 section, when the PEBB (100) is operated for a long time, the PEBB triangular wave signal (302) becomes out of sync with the reference triangular wave signal (301) due to minute changes inside the PEBB (100).

[0084] Specifically, in the t21 interval, an example is illustrated in which the period (P') of the PEBB triangular wave signal (302) becomes shorter than the period (P) of the reference triangular wave signal (301). That is, an example is illustrated in which the period (P') of the PEBB triangular wave signal (302) is shorter than the period (P) of the reference triangular wave signal (301) by -△P.

[0085] PEBB (100) can monitor the period (P') of its PEBB triangular wave signal (302) at a preset period or in real time to check if it is the same as the period (P) of the reference triangular wave signal (301).

[0086] As in the t21 interval, if the period (P') of the PEBB triangular wave signal (302) is different from the period (P) of the reference triangular wave signal (301), the PEBB (100) adjusts the PEBB triangular wave signal (302) so that the two periods become the same. That is, as in the t22 interval, the period (P') of the PEBB triangular wave signal (302) is synchronized with the period of the reference triangular wave signal (301). This can be called 'first-order synchronization'.

[0087] Specifically, in the first synchronization of the t22 interval, the existing PEBB triangular wave signal (302') indicated by the dotted line is adjusted to the new PEBB triangular wave signal (302) indicated by the solid line (adjusted from 302' to 302), thereby making the period (P') of the PEBB triangular wave signal (302) equal to the period (P) of the reference triangular wave signal (301).

[0088] Afterward, it is checked whether a circulating current is generated in multiple PEBBs (100) operating in parallel. This circulating current can be detected through a current sensor (not shown) provided inside the PEBB (100).

[0089] When a circulating current occurs, the maximum value (Max) of the PEBB triangular wave signal (302) is adjusted in the t33 interval.

[0090] When a circulating current occurs between PEBBs (100), the maximum value (Max) of the PEBB triangular wave signal (302) at t23 is adjusted upward or downward. This can be called 'secondary synchronization'.

[0091] At this time, as shown in Fig. 4, the upward or downward adjustment of the maximum value (Max) in the second synchronization must be adjusted in a direction that reduces the circulating current. For example, if the circulating current is reduced by adjusting the maximum value (Max) upward, it must be adjusted upward, and conversely, if the circulating current is reduced by adjusting it downward, it must be adjusted downward. In addition, the maximum value (Max) may be adjusted upward or downward in a direction that reduces the circulating current, and may be adjusted until no circulating current occurs.

[0092] In the t23 section, an example is shown in which the maximum value is lowered from Max1 to Max2. That is, in the t23 section, the existing PEBB triangular wave signal (302') indicated by the dotted line is adjusted to the new PEBB triangular wave signal (302) indicated by the solid line (adjusted from 302' to 302), thereby eliminating the circulating current.

[0093] In this way, the periods of the two signals (301, 302) are synchronized in the first synchronization, and after the circulating current is eliminated by adjusting the maximum value (Max) of the PEBB triangular wave signal (302) upward or downward in the second synchronization, the zero point of the PEBB triangular wave signal (302) is matched with the zero point of the reference triangular wave signal (301).

[0094] Specifically, in the t24 interval, the zero point of the PEBB triangular wave signal (302) is aligned with the zero point (t0) of the reference triangular wave signal (301). This can be called 'third-order synchronization'. In third-order synchronization, the alignment of the zero points of the two signals is such that the zero point of the PEBB triangular wave signal (302) becomes equal to the reference triangular wave signal (301).

[0095] Here, the above zero point may refer to the point where the signal reaches its lowest point.

[0096] As shown in FIGS. 4 and 5, in the present invention, when the period (P') of the PEBB triangular wave signal (302) is different from the period (P) of the reference triangular wave signal (301), the PEBB triangular wave signal (302) is adjusted to synchronize the period (P') of the PEBB triangular wave signal (302) with the period (P) of the reference triangular wave signal (301) (1st synchronization), and subsequently, whether a circulating current occurs is checked, and if it occurs, the maximum value (Max1) of the PEBB triangular wave signal (302) is adjusted upward or downward in a direction to reduce and eliminate the circulating current (2nd synchronization), and finally, the zero point of the PEBB triangular wave signal (302) is matched with the zero point of the reference triangular wave signal (301) (3rd synchronization).

[0097] FIG. 6 is a flowchart showing a method for synchronizing a triangular wave signal according to an embodiment of the present invention.

[0098] Referring to FIG. 6, in the method for synchronizing a triangular wave signal according to an embodiment of the present invention, first, PEBB (100) receives a reference triangular wave signal from an upper controller (200) (S101).

[0099] PEBB (100) generates a PEBB triangular wave signal synchronized with the received reference triangular wave signal (S102).

[0100] PEBB (100) can verify this through real-time monitoring of the PEBB triangular wave signal. Subsequently, if the synchronization between the two signals is disrupted due to the long-term operation of PEBB (100), PEBB (100) determines whether the period (P') of the PEBB triangular wave signal is the same as the period (P) of the reference triangular wave signal (S103).

[0101] If the periods of the two signals are not the same, the PEBB (100) matches the period (P') of the PEBB signal with the period (P) of the reference triangular wave signal through primary synchronization (S104). To do this, the PEBB triangular wave signal is partially adjusted as in '302'→302 of FIGS. 4 and 5.

[0102] Afterwards, a current sensor (not shown) provided inside the PEBB (100) is used to determine whether a circulating current has occurred between the PEBBs (100) (S105).

[0103] If it is determined that a circulating current has occurred, the maximum value (Max) of the PEBB triangular wave signal can be adjusted upward or downward through secondary synchronization to eliminate the circulating current (S106). At this time, the adjustment of the maximum value can proceed in the direction of reducing the circulating current (upward or downward) and can continue until the circulating current is finally eliminated.

[0104] In this way, when the circulating current is removed, the zero point of the PEBB triangular wave signal is aligned with the zero point of the reference triangular wave signal through third-order synchronization (S107). Here, if the zero point of the PEBB triangular wave signal is already aligned with the zero point of the reference triangular wave signal before step S107, step S107 may be omitted.

[0105] If the periods of the two signals are the same in step S103, step S105 may be performed immediately, and if no circulating current occurs in step S105, step S107 may be performed immediately.

[0106] The synchronization method of the triangular wave signal of FIG. 6 can be applied to each of the multiple PEBBs (100) operating in parallel. Each PEBB (100) generates a PEBB triangular wave signal synchronized with a reference triangular wave signal received from the upper controller (200). If the synchronization of the two signals is subsequently disrupted due to the long-term operation of the PEBB (100), synchronization can be performed in the manner of FIG. 4 to FIG. 6, thereby preventing the generation of circulating current between the PEBBs (100).

[0107] Meanwhile, as previously explained, although the present invention describes a phase synchronization method for a triangular wave signal of a PEBB as one embodiment, it should be clearly stated that it can be applied in the same way not only to PEBBs but also to other power converters that use a triangular wave signal as a switching signal for a switching element. That is, in the case where a triangular wave signal is used as a switching signal for a switching element in a power converter, if a controller transmits a reference triangular wave signal to the power converter and the power converter generates a triangular wave signal of the switching signal based on the reference triangular wave signal, the phase synchronization method of the present invention can be applied.

[0108] Although embodiments of the present invention have been described above with reference to the attached drawings, the present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical concept or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. A step of determining whether the period of a triangular wave signal is the same as the period of a reference triangular wave signal; If not identical, a step of adjusting the period of the above triangular wave signal to be identical to the period of the above reference triangular wave signal; A step of determining whether a circulating current occurs after adjusting the above cycle; and A method for synchronizing a triangular wave signal, comprising the step of adjusting the maximum value of the triangular wave signal when the above circulating current occurs.

2. In Claim 1, A method for synchronizing a triangular wave signal, wherein the step of adjusting the maximum value includes the step of adjusting the maximum value upward or downward in a direction in which the circulating current is reduced.

3. In Claim 2, The step of adjusting the maximum value is a method of synchronizing a triangular wave signal by adjusting the maximum value upward or downward until the circulating current is removed.

4. In Claim 1, A method for synchronizing a triangular wave signal, further comprising, after the step of adjusting the maximum value, a step of matching the zero point of the triangular wave signal with the zero point of the reference triangular wave signal.

5. In Claim 4, The step of matching the zero point is a method for synchronizing a triangular wave signal by adjusting the triangular wave signal so that the zero point of the triangular wave signal becomes equal to the zero point of the reference triangular wave signal.

6. In Claim 1, A method for synchronizing a triangular wave signal, comprising, after the step of determining whether the period of the triangular wave signal is the same as the period of a reference triangular wave signal or the step of adjusting the period of the triangular wave signal to be the same as the period of the reference triangular wave signal, further including the step of monitoring in real time whether the circulating current is generated using a current sensor.

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