Method for operating PEBB with optimal efficiency

Abstract

The present invention relates to a method for controlling a power electronic building block (PEBB) to operate in parallel with optimal efficiency. The control method of the present invention comprises the steps of: generating a plurality of efficiency maps in which efficiencies are configured according to the torque of a motor and the number of PEBBs for each of a plurality of speeds of the motor; measuring the speed and torque of the motor; determining, by a higher-level controller, whether an efficiency corresponding to the measured speed and torque of the motor exists in the efficiency maps; when the efficiency exists in the efficiency maps, extracting the number of PEBBs corresponding to an optimal efficiency for the measured speed and torque from the efficiency maps; and operating the extracted number of PEBBs.

Description

Optimal Efficiency Operation Method for PEBB

[0001] The present invention relates to a method for operating a Power Electronics Building Block (PEBB), and more particularly to a method for controlling the PEBB to operate at optimal efficiency.

[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] In the case of power converters equipped on aircraft or ships, since the maximum allowable capacity of a single PEBB is fixed, multiple PEBBs are operated in parallel to form a large-capacity system.

[0008] However, in specific environments such as aircraft or eco-friendly ships, compact power converters are required to efficiently utilize limited space.

[0009] Typically, multiple higher-level controllers are provided to control multiple PEBBs; however, in environments requiring a compact power converter as described above, multiple PEBBs are operated in parallel by a single higher-level controller.

[0010] However, in this case, since the optimal efficiency point differs for each of the multiple PEBBs, the power converter and the entire system may not operate at optimal efficiency during simple parallel operation.

[0011] The present invention aims to provide a method for optimal efficiency operation of PEBBs, which enables operation of multiple PEBBs at optimal efficiency when operating them in parallel with a single upper controller in a power converter.

[0012] The present invention aims to provide a method for operating PEBBs at optimal efficiency by pre-setting an efficiency map according to the speed and number of a plurality of PEBBs, determining the number of PEBBs corresponding to the optimal efficiency at the motor speed of the PEBBs, and operating the PEBBs.

[0013] According to the present invention, a method for optimal efficiency operation of PEBBs is provided, wherein when multiple PEBBs are operated in parallel by a single upper controller, each PEBB is controlled to output the same torque.

[0014] A method for optimal efficiency operation of a PEBB according to an embodiment of the present invention comprises: a step of generating a plurality of efficiency maps, each having an efficiency set according to the commanded torque of the motor and the number of PEBBs for each of the plurality of motor speeds; a step of checking the motor speed and torque; a step of determining in an upper controller whether an efficiency corresponding to the motor speed and commanded torque exists in the efficiency map; a step of, if it exists in the efficiency map, extracting the number of PEBBs corresponding to the optimal efficiency for the speed and torque from the efficiency map; and a step of operating the PEBB with the extracted number.

[0015] In the present invention, after the step of generating the efficiency map, the method further comprises: a step of extracting the correlation between the torque and the efficiency of the generated efficiency map; and a step of generating a formula for calculating the efficiency (y) with the torque (x) as a variable based on the correlation.

[0016] In the present invention, the step of extracting the number of PEBBs comprises: a step of calculating an efficiency corresponding to the speed and torque for each number of PEBBs using the generated formula if they do not exist in the efficiency map; and a step of extracting the number of PEBBs corresponding to the optimal efficiency among the calculated efficiencies.

[0017] In the present invention, the optimal efficiency is the maximum efficiency among the efficiencies of the efficiency map.

[0018] In the present invention, the step of operating the PEBB comprises: selecting a PEBB corresponding to the extracted number among the plurality of PEBBs from the upper controller; transmitting a torque output command to the selected PEBB; and operating the selected PEBB to output a required torque according to the torque output command.

[0019] In the present invention, the selected PEBB is operated to output equal torque.

[0020] A method for optimal efficiency operation of a PEBB according to another embodiment of the present invention comprises: generating an efficiency calculation map including a correlation formula for efficiency corresponding to a plurality of motor speeds, commanded torques, and the number of PEBBs; checking the motor speeds and torques in an upper controller; determining in the upper controller whether a correlation formula for efficiency corresponding to the motor speeds and commanded torques exists in the efficiency calculation map; if it exists in the efficiency map, extracting the number of PEBBs corresponding to the correlation formula representing optimal efficiency for the speeds and torques from the efficiency calculation map; and operating the PEBBs with the extracted number.

[0021] In the present invention, the step of generating the efficiency calculation map comprises: a step of calculating the efficiency according to the commanded torque and the number of PEBBs by operating the motor a plurality of times for each of the motor speeds and commanded torques, while counting the number of PEBBs for each of the motor speeds and commanded torques; a step of generating an efficiency map for the number of PEBBs for each of the motor speeds and commanded torques based on the calculated efficiency; a step of calculating a correlation formula for the efficiency corresponding to the plurality of motor speeds, commanded torques, and the number of PEBBs using the efficiency map; and a step of generating the efficiency calculation map by mapping or assigning to the efficiency calculation map corresponding to the plurality of motor speeds, commanded torques, and the number of PEBBs using the correlation formula.

[0022] In the present invention, the step of calculating the correlation formula comprises: a step of extracting the correlation between the torque and the efficiency of the generated efficiency map; and a step of generating a correlation formula representing the efficiency (y) with the torque (x) as a variable based on the correlation.

[0023] In the present invention, the step of operating the PEBB comprises: selecting a PEBB corresponding to the extracted number among the plurality of PEBBs from the upper controller; transmitting a torque output command to the selected PEBB; and operating the selected PEBB to output a required torque according to the torque output command.

[0024] In the present invention, the selected PEBB is operated to output equal torque.

[0025] The optimal efficiency operation method of PEBB according to an embodiment of the present invention has one or more of the following effects.

[0026] According to the present invention, multiple PEBBs are operated in parallel with a single upper controller, allowing for efficient utilization of limited space.

[0027] According to the present invention, a plurality of PEBBs can be operated with optimal efficiency using a single upper controller.

[0028] According to the present invention, when operating a plurality of PEBBs in parallel, the number of PEBBs to be operated can be determined to operate at optimal efficiency.

[0029] According to the present invention, when operating a plurality of PEBBs in parallel, each PEBB can be controlled to output the same torque.

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

[0031] FIG. 2 is an exemplary configuration diagram of a power converter according to an embodiment of the present invention.

[0032] FIG. 3 is an example diagram in which a plurality of PEBBs output torque in response to the command torque of a higher-level controller according to an embodiment of the present invention.

[0033] FIG. 4 is an example of an efficiency map of a PEBB according to one embodiment of the present invention.

[0034] FIG. 5 is an example diagram of a correlation equation showing the correlation between torque and efficiency according to the speed of the motor and the number of PEBBs according to one embodiment of the present invention.

[0035] FIG. 6 is a flowchart for explaining a method for operating a PEBB at optimal efficiency according to an embodiment of the present invention.

[0036] FIG. 7 is an example of an efficiency map of a PEBB according to another embodiment of the present invention.

[0037] FIG. 8 is an example of an efficiency calculation map showing the correlation formula between torque and efficiency according to the speed of the motor and the number of PEBBs according to another embodiment of the present invention.

[0038] FIG. 9 is a flowchart for explaining a method for operating a PEBB at optimal efficiency according to another embodiment of the present invention.

[0039] FIG. 10 is a flowchart for explaining the optimal efficiency operation method of a PEBB according to an embodiment of the present invention.

[0040] 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.

[0041] FIG. 1 is an exemplary diagram of a power system according to an embodiment of the present invention.

[0042] 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.

[0043] This power system may be configured to include a power converter (10), a power generation facility (20), a load (50), and an energy storage device (40).

[0044] 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).

[0045] The power converter (10) can distribute or control the entire power flow of the power system of the ship (1).

[0046] 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.

[0047] The load (30) may include loads necessary to operate the vessel (1). In this embodiment, the load (30) may include, for example, a motor.

[0048] FIG. 2 is an exemplary configuration diagram of a power converter according to an embodiment of the present invention.

[0049] Referring to FIG. 2, a power converter (10) according to one embodiment of the present invention may include a plurality of power electronics building blocks (PEBB: Power Electronics Building Block) (100) and a higher-level controller (200) that controls the plurality of PEBBs (100).

[0050] The power converter (10) is installed in an aircraft or an eco-friendly ship (1) and can convert and distribute any power into desired power using multiple PEBBs (100).

[0051] 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.

[0052] 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).

[0053] In this embodiment, a plurality of PEBBs (100) operate in parallel with each other. Each PEBB (100) can output a required torque according to the command of the upper controller (200).

[0054] The upper controller (200) can operate and control multiple PEBBs (100).

[0055] In this embodiment, one upper controller (200) controls N (N≥2, integer) PEBBs (100) to operate in parallel.

[0056] The upper controller (200) can transmit a command for torque output to each PEBB (100).

[0057] Accordingly, each PEBB (100) can be operated to output the required torque according to the command torque transmitted to it.

[0058] The upper controller (200) may include a processor that executes a program and / or software that calculates a correlation formula based on the correlation between the commanded torque and efficiency to be described later and the correlation formula, and generates an efficiency map and an efficiency calculation map using the correlation formula.

[0059] FIG. 3 is an example diagram showing a plurality of PEBBs outputting torque in response to the commanded torque of a higher-level controller according to an embodiment of the present invention.

[0060] Figure 3 illustrates an example in which three PEBBs (100) are operated in parallel.

[0061] One upper controller (200) can check the total torque to be output from multiple PEBBs (100) and output a commanded torque to each PEBB (100).

[0062] Multiple PEBBs (100) can each output the required torque according to the received command torque.

[0063] For example, there are three ways to operate N PEBBs (100) in parallel to produce a total torque output of X MNm.

[0064] That is, one of the following methods can be used: (i) operating all N PEBBs (100) in parallel to output X / N MNm of torque each, (ii) operating n PEBBs (100) out of N to output X / (Nn) MNm of torque each, or (iii) operating only 1 PEBB (100) out of N to output X MNm of torque.

[0065] Here, it is important that when multiple PEBBs (100) are operated in parallel, each PEBB (100) must output a torque of the same magnitude. To this end, the upper controller (200) can divide the total torque to be output from the power converter by the number of PEBBs (100) and send a command to each PEBB (100) to output a torque of equal magnitude.

[0066] Figures 3 (a) and (b) illustrate, for example, a method for outputting a total torque of 1 MNm from an upper controller (200) when three PEBBs (100) are operated in parallel.

[0067] FIG. 3(a) shows a method of operating all three PEBBs (100) in parallel to output a torque of 0.33 MNm each, FIG. 3(b) shows a method of operating two of the three PEBBs (100) in parallel to output a torque of 0.5 MNm each, and FIG. 3(c) shows a method of operating only one of the three PEBBs (100) to output a torque of 1 MNm.

[0068] In this way, the upper controller (200) calculates the torque to be output from each PEBB (100) equally based on the total torque to be output and the number of PEBBs (100) to be operated, and then transmits a command torque to each PEBB (100) to output each torque. Accordingly, each PEBB (100) outputs equal torque according to the command torque received from the upper controller (200).

[0069] In this case, since multiple PEBBs (100) have different optimal efficiency points for operation, there may be cases where the power converter (10) and the system are not operated at optimal efficiency during simple parallel operation. Therefore, it is important to determine the number of PEBBs (100) that can be operated at optimal efficiency for the total torque output.

[0070] In the present invention, in one embodiment, the number of PEBBs (100) that can be operated at optimal efficiency is determined by using an efficiency map of PEBBs (100) set in a higher controller (200), or in another embodiment, by using an efficiency calculation map of PEBBs (100) set in a higher controller (200).

[0071] FIG. 4 is an example of an efficiency map of a PEBB according to one embodiment of the present invention.

[0072] Referring to FIG. 4, the efficiency map of the PEBB according to the present invention is used to determine the number of PEBBs that can be operated at optimal efficiency according to the load, i.e., the speed (RPM) and commanded torque of the motor when operating a plurality of PEBBs (100) in parallel.

[0073] In this embodiment, when operating multiple PEBBs (100) in parallel, the efficiency map of the PEBB can be pre-set by measuring the efficiency of each while sequentially changing the motor speed and torque and the number of PEBBs to be operated at optimal efficiency.

[0074] For example, FIG. 4 shows an efficiency map created by pre-measuring the efficiency while sequentially increasing the commanded torque and the number of PEBBs when, for example, the motor speed is 10 RPM.

[0075] In this embodiment, the efficiency map can be created by calculating the efficiency in advance based on the motor speed and commanded torque and the number of PEBBs through experiments or simulations.

[0076] In the drawing, an efficiency map is illustrated exemplarily only for a motor speed of 10 RPM, but efficiency maps can be created for other speeds in the same way.

[0077] The more motor speeds there are, the better the efficiency map is. That is, it is better to create 5 efficiency maps in units of 5, such as 5, 10, 15, 20, 25, 30 RPM, rather than 3 efficiency maps in units of 10, such as 10, 20, 30 RPM, and it is even better to create 30 efficiency maps in units of 1, such as 1~30 RPM.

[0078] Meanwhile, as shown in Fig. 4, a correlation formula can be generated to calculate efficiency (y) with torque as a variable (x) for multiple motor speeds and the number of PEBBs in an efficiency map in which multiple efficiencies are calculated through experiments or simulations.

[0079] In other words, by utilizing the correlation between multiple torque (x) and efficiency (y), the correlation coefficient between two variables (x,y) can be calculated, and by using this correlation coefficient, a correlation formula corresponding to the correlation between the two variables (x,y) can be generated.

[0080] In FIG. 4, correlation equations 11 to 13 between torque and efficiency are calculated, respectively, when 1 to 3 PEBBs are each operated at 10 RPM. These correlation equations are illustrated in FIG. 5.

[0081] FIG. 5 is an example of a correlation equation between torque and efficiency according to motor speed and the number of PEBBs according to one embodiment of the present invention.

[0082] Referring to Fig. 5, the formula for efficiency (y) according to torque (x) generated through experiment or simulation based on motor speed and the number of PEBBs to be operated in the efficiency map of Fig. 4 is y=k4x 4 + k3x 3 + k2x 2 It is represented as + k1x + k0. Here, k0~k4 are correlation coefficients for x obtained through the correlation between torque (x) and efficiency (y) in the efficiency map of Fig. 4.

[0083] These formulas can be used to determine the torque and the number of PEBBs in operation that are not calculated in the efficiency map of FIG. 4. For example, FIG. 4 shows the efficiency when 1 to 3 PEBBs are operated when the torque is 0.64 for a motor speed of 10 RPM, and then shows the efficiency when 1 to 3 PEBBs are operated when the torque is 1.27. However, there is no efficiency map between torques of 0.64 and 1.27. In this case, it can be calculated using the above formulas. That is, when the motor speed is 10 RPM, the efficiency (y) for each number of PEBBs in operation for a torque (x) of 0.9 can be calculated using the first formula of FIG. 5.

[0084] The correlation between the commanded torque and efficiency, the correlation formula based on the correlation, and the efficiency map can be calculated in the upper controller (200) using the correlation formula.

[0085] To this end, the upper controller (200) includes a processor that executes a program and / or software capable of calculating and generating correlations, correlation formulas and efficiency maps.

[0086] FIG. 6 is an example of an efficiency calculation map showing the correlation formula between torque and efficiency according to motor speed and the number of PEBBs according to another embodiment of the present invention.

[0087] Referring to FIG. 6, the efficiency calculation map according to the present invention can be generated using the correlation formula created in FIG. 5. That is, the correlation formula 11-13 calculated in the example of FIG. 5 can be mapped to a position corresponding to the efficiency calculation map of FIG. 6.

[0088] Specifically, the efficiency calculation map can be assigned correlation formulas according to motor speed, commanded torque, and the number of PEBBs to be operated. At this time, the correlation formulas generated in FIG. 5 can be mapped and assigned to the efficiency calculation map of FIG. 6, respectively.

[0089] For example, correlation equation 11 of FIG. 5 is mapped and assigned to a position corresponding to 10 RPM, 1.54 torque, and 1 PEBB in the efficiency calculation map of FIG. 6, and likewise, correlation equations 12 and 13 of FIG. 5 can also be mapped and assigned to positions corresponding to the efficiency calculation map of FIG. 6.

[0090] Although Figure 6 shows only examples with a motor speed of 10 RMP, a torque of 1.54, and 1 to 3 PEBBs, it is obvious that more efficiency calculation maps can be produced by applying the same method to different motor speeds, different torques, and different numbers of PEBBs, as in the example in Figure 4.

[0091] In this way, by mapping and assigning the correlation equations generated in Fig. 5 to the efficiency calculation map of Fig. 6, an efficiency calculation map is completed in which correlation equations corresponding to all motor speeds, commanded torques, and PEBB operation counts are assigned.

[0092] Since the correlation formulas generated in the efficiency calculation map are derived from multiple experiments or simulations tailored to the corresponding motor speed, commanded torque, and number of PEBB operations, the more experiments or simulations are performed, the more accurate the correlation formula will be.

[0093] Since torque appears discretely in the efficiency calculation map above, torque not displayed in the efficiency calculation map can be calculated using a known interpolation method.

[0094] The correlation between the commanded torque and efficiency, the correlation formula based on the correlation, and the efficiency calculation map using the correlation formula can be calculated in the upper controller (200).

[0095] To this end, the upper controller (200) includes a processor that executes a program and / or software capable of calculating and generating correlations, correlation formulas and efficiency calculation maps.

[0096] FIG. 7 is a flowchart illustrating a method for operating a PEBB at optimal efficiency according to an embodiment of the present invention.

[0097] Referring to FIG. 7, in the optimal efficiency operation method of a PEBB according to one embodiment of the present invention, a plurality of efficiency maps are first generated in advance, each having a motor torque and an efficiency according to the number of PEBBs for various speeds of the motor (S101).

[0098] The above efficiency map can be generated as shown in FIGS. 4 and FIGS. 5. This efficiency map is stored in memory (not shown) inside the upper controller (200).

[0099] And, using the correlation between torque and efficiency of the generated efficiency map, a correlation formula can be generated to calculate efficiency (y) with torque (x) as a variable (S102).

[0100] Afterwards, the actual speed of the motor is measured for optimal efficiency operation of the PEBB (S103), and the command torque for the motor transmitted from the upper controller (200) is checked (S104).

[0101] The upper controller (200) determines whether there is an efficiency corresponding to the measured motor speed and commanded torque in the efficiency map (S105).

[0102] If present in the efficiency map, the number of PEBBs corresponding to the optimal efficiency at the above speed and commanded torque is extracted from the efficiency map (S106).

[0103] However, if it does not exist in the efficiency map, the efficiency corresponding to the measured speed and torque for each number of PEBBs is calculated using the correlation formula above (S107), and the number of PEBBs corresponding to the optimal efficiency among the calculated efficiencies is extracted (S108).

[0104] Then, the PEBB is operated with the extracted number (S109). This allows the PEBB to be operated at optimal efficiency.

[0105] Here, while it is desirable for the optimal efficiency to be the maximum efficiency, this is not necessarily the case. It is necessary to decide whether to determine the optimal efficiency as the maximum efficiency by considering the overall situation of the power converter and the entire system.

[0106] In addition, the step of operating the PEBB in step S109 involves selecting a PEBB corresponding to the number of extracted PEBBs from among a plurality of PEBBs from the upper controller (200), and transmitting a torque output command to the selected PEBB, and then operating the PEBB to output the required torque according to the received torque output command. Furthermore, the selected PEBB can be operated to output equal torque.

[0107] FIG. 8 is an example of an efficiency map of a PEBB according to another embodiment of the present invention.

[0108] Referring to FIG. 8, an efficiency map of a PEBB according to another embodiment of the present invention can be generated by measuring the efficiency multiple times while sequentially changing the number of PEBBs to be operated according to motor speed and command torque when operating the PEBB.

[0109] For example, in FIG. 8, when the motor speed is 10 RPM and the commanded torque is 1.54, the efficiency is measured each time the PEBB is operated multiple times with one PEBB, and then the efficiency is measured each time the PEBB is operated multiple times with two and three PEBBs, respectively, to generate an efficiency map.

[0110] That is, when the motor speed is 10 RPM and the commanded torque is 1.54, the PEBB is operated multiple times with 1 to 3 units respectively, and the efficiency of each is calculated to generate an efficiency map.

[0111] In FIG. 8, for example, when the command torque is 1.54, the efficiency of each PEBB is calculated when it is operated multiple times with one PEBB at 10 RPM, and correlation equation 21 is calculated for this. In the same way, the efficiency of each PEBB is calculated when it is operated multiple times with two PEBBs to calculate correlation equation 22, and the efficiency of each PEBB is calculated when it is operated multiple times with three PEBBs to calculate correlation equation 23.

[0112] This correlation formula allows for the pre-calculation of efficiency based on motor speed, commanded torque, and the number of operating PEBBs through experiments or simulations.

[0113] In FIG. 8, an efficiency map is illustrated exemplarily only for a motor speed of 10 RPM and a torque of 1.54, but of course, efficiency maps can be created for other speeds and other torques (e.g., the torque in FIG. 4) in the same way. It is also better to have as many of these efficiency maps as possible.

[0114] The above correlation formula can be generated by calculating the efficiency (y) with torque as a variable (x) according to the number of PEBBs for each speed in an efficiency map where multiple efficiencies are calculated through iterative experiments or simulations.

[0115] Efficiency maps can be created not only for the torque of 1.54 but also for multiple other torques. The efficiency maps created in this way can be used to create an efficiency calculation map as shown in FIG. 9.

[0116] FIG. 9 is an example of an efficiency calculation map showing the correlation formula between torque and efficiency according to motor speed and the number of PEBBs according to another embodiment of the present invention.

[0117] Referring to FIG. 9, the efficiency calculation map according to the present invention can be generated using the efficiency map created in FIG. 8. That is, the correlation equations 21-23 calculated in the example of FIG. 8 can be mapped to positions corresponding to the efficiency calculation map of FIG. 9.

[0118] Specifically, the efficiency calculation map can be assigned correlation formulas according to motor speed, commanded torque, and the number of PEBBs to be operated. At this time, the correlation formulas generated in FIG. 8 can be mapped and assigned to the efficiency calculation map of FIG. 9, respectively.

[0119] For example, correlation equation 21 of FIG. 8 is mapped and assigned to a position corresponding to 10 RPM, 1.54 torque, and 1 PEBB in the efficiency calculation map of FIG. 9, and likewise, correlation equations 22 and 23 of FIG. 8 can also be mapped and assigned to positions corresponding to the efficiency calculation map of FIG. 9.

[0120] Although Figure 9 shows only examples with a motor speed of 10 RMP, a torque of 1.54, and 1 to 3 PEBBs, it is obvious that more efficiency calculation maps can be produced by applying the same method to different motor speeds, different torques, and different numbers of PEBBs, as in the example in Figure 4.

[0121] In this way, the correlation equations generated in Fig. 8 are mapped or assigned to the efficiency calculation map in Fig. 9, thereby completing an efficiency calculation map in which correlation equations corresponding to all motor speeds, commanded torques, and PEBB operation counts are assigned.

[0122] Since the correlation formulas generated in the efficiency calculation map are derived from multiple experiments or simulations tailored to the corresponding motor speed, commanded torque, and number of PEBB operations, the more experiments or simulations are performed, the more accurate the correlation formula will be.

[0123] Since torque appears discretely in the efficiency calculation map above, torque not displayed in the efficiency calculation map can be calculated using a known interpolation method.

[0124] The correlation equations of FIGS. 4 and 5 and the correlation equations of FIGS. 8 and 9 can be compared with each other. For example, correlation equation 11 of FIGS. 4 and 5 is calculated based on the efficiency for multiple torques when there is one PEBB at a motor speed of 10 RPM, and correlation equation 21 of FIGS. 8 and 9 is calculated based on the efficiency for multiple torques when there is one PEBB at a motor speed of 10 RPM.

[0125] The correlation between the commanded torque and efficiency, the correlation formula based on the correlation, and the efficiency calculation map using the correlation formula can be calculated in the upper controller (200).

[0126] To this end, the upper controller (200) includes a processor that executes a program and / or software capable of calculating and generating correlations, correlation formulas and efficiency calculation maps.

[0127] FIG. 10 is a flowchart illustrating an optimal efficiency operation method of a PEBB according to an embodiment of the present invention.

[0128] Referring to FIG. 10, in the optimal efficiency operation method of a PEBB according to an embodiment of the present invention, first, an efficiency calculation map is generated that includes a correlation formula of efficiency according to the motor's commanded torque and the number of PEBBs for various speeds of the motor (S201). This efficiency calculation map is stored in a memory (not shown) inside an upper controller (200).

[0129] Afterwards, the actual speed of the motor is measured (S202) and the commanded torque of the motor is checked (S203) for optimal efficiency operation of the PEBB.

[0130] The upper controller (200) checks the correlation formula of the efficiency corresponding to the motor speed and commanded torque in the efficiency calculation map (S204).

[0131] The upper controller (200) extracts the number of PEBBs representing the correlation formula of optimal efficiency for the motor speed and commanded torque (S205).

[0132] This involves extracting the number of PEBBs assigned a correlation formula that represents the optimal efficiency corresponding to the speed and commanded torque, among the multiple correlation formulas assigned to the efficiency calculation map.

[0133] Then, the PEBB is operated with the extracted number (S206). This allows the PEBB to be operated at optimal efficiency.

[0134] The step of operating the PEBB in step S206 involves selecting a PEBB corresponding to the number of extracted PEBBs from among a plurality of PEBBs from the upper controller (200), and transmitting a torque output command to the selected PEBB, and then operating the PEBB to output the required torque according to the received torque output command. Additionally, the selected PEBB can be operated to output equal torque.

[0135] In the above S201 step, the efficiency calculation map can be generated as follows. That is, for each motor speed, the number of PEBBs is calculated for each of the multiple commanded torques of the motor, and each is operated multiple times to calculate the efficiency according to the commanded torque and the number of PEBBs. Based on the calculated efficiency, an efficiency map for the number of PEBBs for each motor speed and multiple commanded torques is generated.

[0136] Then, using the generated efficiency map, a correlation formula for efficiency corresponding to multiple motor speeds, commanded torques, and PEBB counts is calculated, and an efficiency calculation map is generated by mapping or assigning the said correlation formula to an efficiency calculation map corresponding to multiple motor speeds, commanded torques, and PEBB counts.

[0137] At this time, in order to calculate the above correlation formula, the correlation between torque and efficiency in the efficiency map is extracted, and based on this correlation, a correlation formula representing efficiency (y) with torque (x) as a variable is generated.

[0138] As explained above, in the method for optimal efficiency operation of a PEBB according to an embodiment of the present invention, when operating multiple PEBBs in parallel with a single upper controller, the efficiency corresponding to the load, i.e., the motor speed and torque, is pre-set for each number of PEBBs through experiment or simulation for the PEBBs to be operated. Then, to achieve optimal efficiency operation of the PEBBs, the number of PEBBs capable of operating at optimal efficiency corresponding to the motor speed and torque is determined, and the PEBBs are operated with that number.

[0139] 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 generating a plurality of efficiency maps, each having an efficiency set according to the commanded torque of the motor and the number of PEBBs for each of the plurality of motor speeds; Step of checking the motor speed and torque above; A step of determining whether an efficiency corresponding to the motor speed and commanded torque exists in the efficiency map in the upper controller; If present in the efficiency map, a step of extracting the number of PEBBs corresponding to the optimal efficiency for the speed and torque from the efficiency map; and A method for optimal efficiency operation of a PEBB, comprising the step of operating the PEBB with the number of extracted items.

2. In Claim 1, After the step of generating the above efficiency map, A step of extracting the correlation between the torque and efficiency of the efficiency map generated above; and A method for optimal efficiency operation of a PEBB, further comprising the step of generating a correlation formula to calculate efficiency (y) with the torque (x) as a variable based on the above correlation.

3. In Claim 2, The step of extracting the number of PEBBs above is, If not present in the efficiency map above, a step of calculating the efficiency corresponding to the speed and torque for each number of PEBBs using the generated correlation formula; and A method for optimal efficiency operation of PEBBs, comprising the step of extracting the number of PEBBs corresponding to the optimal efficiency among the above calculated efficiencies.

4. In Claim 1, The above optimal efficiency is the maximum efficiency among the efficiencies of the above efficiency map, which is the optimal efficiency operation method of the PEBB.

5. In Claim 1, The step of operating the above PEBB is, A step of selecting a PEBB corresponding to the extracted number among the plurality of PEBBs in the above-mentioned upper controller; A step of transmitting a torque output command to the selected PEBB; and A method for optimal efficiency operation of a PEBB, comprising the step of operating the selected PEBB to output a required torque according to the torque output command.

6. In Claim 5, The above-described selected PEBB is an optimal efficiency operation method for PEBBs that operates to output equal torque.

7. A step of generating an efficiency calculation map including a correlation formula for efficiency corresponding to a plurality of motor speeds, commanded torques, and the number of PEBBs; A step of checking the motor speed and torque in the upper controller; A step of determining whether a correlation formula for efficiency corresponding to the motor speed and commanded torque exists in the efficiency calculation map in the upper controller; If present in the efficiency map, a step of extracting the number of PEBBs corresponding to the correlation formula representing the optimal efficiency for the speed and torque in the efficiency calculation map; and A method for optimal efficiency operation of a PEBB, comprising the step of operating the PEBB with the number of extracted items.

8. In Claim 7, The step of generating the above efficiency calculation map is, A step of calculating efficiency according to the commanded torque and the number of PEBBs by operating each of the multiple speeds of the motor and the multiple commanded torques of the motor multiple times while counting the number of PEBBs; A step of generating an efficiency map for the number of PEBBs for each of the plurality of commanded torques for each motor speed based on the above-calculated efficiency; A step of calculating a correlation formula for efficiency corresponding to the plurality of motor speeds, commanded torque, and number of PEBBs using the efficiency map above; A method for optimal efficiency operation of a PEBB, comprising the step of generating an efficiency calculation map by mapping or assigning to an efficiency calculation map corresponding to a plurality of motor speeds, commanded torques, and the number of PEBBs using the above correlation formula.

9. In Claim 8, The step of calculating the above correlation formula is, A step of extracting the correlation between the torque and efficiency of the efficiency map generated above; and A method for optimal efficiency operation of a PEBB, comprising the step of generating a correlation formula representing efficiency (y) with the torque (x) as a variable based on the above correlation.

10. In Claim 7, The step of operating the above PEBB is, A step of selecting a PEBB corresponding to the extracted number among the plurality of PEBBs in the above-mentioned upper controller; A step of transmitting a torque output command to the selected PEBB; and A method for optimal efficiency operation of a PEBB, comprising the step of operating the selected PEBB to output a required torque according to the torque output command.

11. In Claim 10, The above-described selected PEBB is an optimal efficiency operation method for PEBBs that operates to output equal torque.

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