Apparatus for controlling permanent magnet synchronous motor, and method therefor

Abstract

The present invention relates to an apparatus for controlling a permanent magnet synchronous motor, and a method therefor. In a reactive power control-based motor V / f control system, the apparatus for controlling a permanent magnet synchronous motor, according to the present invention, calculates a voltage proportional to a motor operating frequency command and generates a final voltage command by adding a reactive power control-based voltage variation, wherein the reactive power control-based voltage variation is calculated using a saturation inductance according to an output torque, thereby enabling, as compared to a conventional method in which reactive power is calculated using a fixed inductance, high-efficiency control close to an actual maximum torque per ampere (MTPA) in which saturation characteristics of the motor are taken into consideration even during V / f control.

Description

Permanent Magnet Synchronous Motor Control Device and Method

[0001] The present invention relates to electric motor control technology, and more particularly to technology for controlling permanent magnet synchronous motors with high efficiency.

[0002] Electric motor drive systems account for a significant portion of industrial electricity consumption, approximately 65%. Therefore, improving the efficiency of electric motors can lead to significant energy savings.

[0003] Many countries are implementing policies to expand the supply of high-efficiency electric motors to save energy, and synchronous motors are being considered as replacements for induction motors, which account for the majority of industrial motors.

[0004] First, permanent magnet synchronous motors have advantages over induction motors in terms of output and efficiency because the presence of permanent magnets allows them to generate greater torque within the same volume, resulting in higher power density and enabling the miniaturization and weight reduction of the motor drive system. Second, since there is no rotor circuit, losses caused by the rotor do not occur, leading to higher efficiency compared to induction motors.

[0005] Among the devices using industrial electric motors, fluid devices with secondary load characteristics, such as fans, pumps, and compressors, account for a significant proportion. Although these fluid device systems are designed based on maximum load, they operate at a partial load lower than the maximum load for most of the time, which presents a problem in that efficiency is not optimized.

[0006] In addition, conventional V / f (Voltage / frequency) control methods based on reactive power control calculate the reactive power command using the inductance at the rated operating point calculated from the motor's nameplate information or the inductance obtained from the initial inductance estimation.

[0007] However, while the inductance value used at this time is constant, the actual inductance is a parameter that changes according to the current magnitude due to saturation. Therefore, if the inductance value is fixed as a constant, there is a difference from the actual MTPA (Maximum Torque Per Ampere) operating point, and the error becomes larger for motors with severe saturation, which leads to a problem of lower motor efficiency.

[0008] The inventors of the present invention have been making research efforts to solve the problems of the conventional synchronous motor V / f control method. After much effort to provide a permanent magnet synchronous motor control device and method capable of increasing the efficiency of a permanent magnet synchronous motor by replacing the inductance, which was fixed as a constant in the conventional technology, with an inductance that reflects saturation according to the estimated torque, the inventors have completed the present invention.

[0009] The objective of the present invention is to provide a permanent magnet synchronous motor control device and method capable of increasing motor efficiency by controlling the synchronous motor with an inductance that reflects saturation rather than a fixed constant inductance.

[0010] Meanwhile, other unspecified objects of the present invention will be further considered to the extent that they can be easily inferred from the following detailed description and effects.

[0011] A permanent magnet synchronous motor control device according to the present invention is characterized in that, in a motor V / f control system based on reactive power control, a voltage proportional to a motor operating frequency command is calculated and a voltage fluctuation component based on reactive power control is added to generate a final voltage command, wherein the voltage fluctuation component based on reactive power control is calculated using a saturation inductance according to the output torque.

[0012] The above processor is characterized by estimating the output torque using the output power and operating speed command of the motor drive inverter.

[0013] The processor is characterized by applying a low-pass filter (LPF) to the estimated output torque to calculate a saturation inductance according to the output torque.

[0014] The above processor, according to the following mathematical formula (1), the output torque (T e Saturation inductance according to ) ((L(T e It is characterized by calculating )).

[0015] (1)

[0016] Here, L q is the q-axis inductance according to the q-axis current, and I s is the motor stator current, β is the angle between the stator current and the q-axis current, and P is the number of motor poles.

[0017] The above processor is the q-axis current in the above mathematical formula (1). The above output torque (T e The output torque (T) above is approximated by the following mathematical formula (2) as ) e Saturation inductance (L(T) according to ) e It is characterized by calculating )).

[0018] (2)

[0019] The above processor has a q-axis inductance (L) according to the output torque. q (T e It is characterized by pre-calculating )) and the above tanβ and storing them in a look-up table.

[0020] The above motor is characterized by being a Surface Mounted Permanent Magnet Synchronous Motor (SPSM) or an Interior Permanent Magnet Synchronous Motor (IPSM).

[0021] In addition, the permanent magnet synchronous motor control device according to the present invention includes a V / f control unit that receives a motor operating frequency command and outputs a voltage command; a reactive power control unit that receives a variable including an inductance and outputs a voltage fluctuation; and an summer that sums the voltage command and the voltage fluctuation to output a final voltage command, wherein the reactive power control unit can output the voltage fluctuation based on a saturated inductance according to the output torque.

[0022] A permanent magnet synchronous motor control method according to another embodiment of the present invention comprises: a step of calculating a voltage proportional to a motor operating frequency command; a step of calculating a voltage fluctuation based on reactive power control; and a step of generating a final voltage command by adding the voltage proportional to the motor operating frequency command and the voltage fluctuation based on reactive power control, wherein the voltage fluctuation based on reactive power control is calculated using a saturation inductance according to output torque.

[0023] According to the present invention, by calculating the inductance based on the output torque of a permanent magnet synchronous motor and calculating the reactive power command, it is possible to achieve high-efficiency operation close to actual MTPA operation considering the saturation characteristics of the motor even during V / f control.

[0024] Meanwhile, it should be added that even if an effect is not explicitly mentioned here, the effects described in the following specification and the provisional effects expected by the technical features of the present invention are treated as described in the specification of the present invention.

[0025] FIG. 1 is a schematic structural diagram of a permanent magnet synchronous motor control device according to a preferred embodiment of the present invention.

[0026] FIG. 2 is a more detailed structural diagram of a processor of a permanent magnet synchronous motor control device according to a preferred embodiment of the present invention.

[0027] FIG. 3 shows a schematic configuration of a permanent magnet synchronous motor control device and an entire motor system according to a preferred embodiment of the present invention.

[0028] FIG. 4 is a more detailed structural diagram of the saturation inductance calculation unit of a permanent magnet synchronous motor control device according to a preferred embodiment of the present invention.

[0029] Figure 5 shows the relationship between the phase angle β between the stator current and the q-axis current of the motor.

[0030] FIG. 6 is a schematic flowchart of a permanent magnet synchronous motor control method according to another preferred embodiment of the present invention.

[0031] FIG. 7 is a drawing for illustrating a computing environment including a computing device according to another preferred embodiment of the present invention.

[0032] ※ It should be noted that the attached drawings are provided as examples for reference to help understand the technical concept of the present invention, and the scope of the rights of the present invention is not limited by them.

[0033] Hereinafter, specific embodiments according to embodiments of the present disclosure will be described with reference to the drawings. The following detailed description is provided to facilitate a comprehensive understanding of the methods, apparatuses, and / or systems described herein. However, this is merely illustrative and the present invention is not limited thereto.

[0034] In describing the embodiments of the present disclosure, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the embodiments. Furthermore, terms used below are defined with consideration of their functions in the present invention, and these may vary depending on the intentions or practices of the user or operator. Therefore, such definitions should be based on the content throughout this specification. Terms used in the detailed description are intended merely to describe specific embodiments and should not be limiting. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form. In this description, expressions such as "include" or "comprise" are intended to refer to certain characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof other than those described. Additionally, terms such as "...part," "...unit," "module," and "block" described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0035]

[0036] FIG. 1 is a schematic structural diagram of a permanent magnet synchronous motor control device according to a preferred embodiment of the present invention.

[0037] A permanent magnet synchronous motor control device (10) according to the present invention may include one or more processors (11), memory (12) and sensors (13).

[0038] The permanent magnet synchronous motor control device (10) aims to increase the efficiency of the motor by generating a reactive power command using an inductance that reflects saturation according to the estimated output torque of the motor when controlling the synchronous motor V / f (voltage / frequency).

[0039] In this case, the motor may be a Surface Mounted Permanent Magnet Synchronous Motor (SPSM) or an Interior Permanent Magnet Synchronous Motor (IPSM).

[0040] The permanent magnet synchronous motor control device (10) may be a computing terminal. For example, the permanent magnet synchronous motor control device (10) may be a general-purpose computing system such as a desktop PC, laptop PC, tablet PC, netbook computer, workstation, PDA, smartphone, smart pad, or mobile phone, or a dedicated embedded system implemented based on Embedded Linux, but is not limited thereto.

[0041] The memory (12) may store instructions, data structures, and program code that can be read by the processor (11). In embodiments, at least the operations performed by the processor (11) may be implemented by executing the instructions or code of the program stored in the memory (12).

[0042] The memory (12) may include a flash memory type, a hard disk type, a multimedia card micro type, a card type memory (e.g., SD or XD memory, etc.), a non-volatile memory including at least one of ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), PROM (Programmable Read-Only Memory), magnetic memory, a magnetic disk, and an optical disk, and a volatile memory such as RAM (Random Access Memory) or SRAM (Static Random Access Memory).

[0043] The memory (12) can store one or more instructions or programs that the permanent magnet synchronous motor control device (10) can use to generate a reactive power command using an inductance that reflects saturation.

[0044] The processor (11) controls the overall operations of the permanent magnet synchronous motor control device (10). For example, the processor (11) can control the overall operations of the permanent magnet synchronous motor control device (10) for controlling the synchronous motor by executing one or more instructions stored in memory (12).

[0045] The processor (11) may be composed of at least one of, for example, a Central Processing Unit, a microprocessor, a Graphic Processing Unit, ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), an Application Processor, a Neural Processing Unit, or an AI-dedicated processor designed with a hardware structure specialized for processing AI models, but is not limited thereto.

[0046] The sensor (13) may include a voltage sensor or a current sensor for measuring the voltage and current of the motor, but is not limited thereto.

[0047] FIG. 2 is a more detailed structural diagram of a processor of a permanent magnet synchronous motor control device according to a preferred embodiment of the present invention.

[0048] The processor (11) includes a saturation inductance calculation unit (21), a reactive power control unit (22), a frequency voltage conversion unit (23), an inverter voltage generation unit (24), and a V / f control unit (25).

[0049] The saturation inductance calculation unit (21) calculates a saturation inductance that reflects the output torque of the motor instead of the inductance that was conventionally used as a fixed constant.

[0050] The reactive power control unit (22) calculates the voltage fluctuation using the active power, the motor speed command, and the saturated inductance calculated by the saturated inductance calculation unit (21).

[0051] The frequency voltage conversion unit (23) converts the speed command into a voltage command value based on the V / f (Voltage / frequency) relationship, adds this to the voltage fluctuation component to generate a final output voltage, which is converted by the inverter voltage generation unit (24) and transmitted to the inverter for driving the motor.

[0052] FIG. 3 shows a schematic configuration of a permanent magnet synchronous motor control device and an entire motor system according to a preferred embodiment of the present invention.

[0053] The motor (1) is driven by receiving three-phase power from the inverter (2), and the permanent magnet synchronous motor control device (10) provides an output voltage ( It will control ).

[0054] The output voltage is the output voltage command value ( ) and voltage fluctuations( The sum of the inputs to the summer (26) and the outputs is input to the inverter voltage generation unit (24) and generated through axis conversion.

[0055] The configuration of the frequency voltage conversion unit (23) and the inverter voltage generation unit (24) is a widely known configuration, so a detailed description is omitted here.

[0056] FIG. 4 is a more detailed structural diagram of the saturation inductance calculation unit of a permanent magnet synchronous motor control device according to a preferred embodiment of the present invention.

[0057] The saturation inductance calculation unit (21) may include an effective power calculation unit (41), an output torque calculation unit (42), a low-pass filter (LPF) (43), and a torque-inductance conversion unit (44).

[0058] The active power calculation unit (41) calculates the current command voltage ( ) and current value( Using ) the following formula for active power ( Calculate )

[0059] Equation (1)

[0060] The output torque calculation unit (42) calculates the effective power using the mechanical operating speed command ( The output torque is estimated by dividing by ).

[0061] (2)

[0062] The estimated output torque passes through a low-pass filter (43) and is used as a factor of the torque-inductance converter (44).

[0063] The torque-inductance converter (44) undergoes the following process to obtain a saturated inductance (L(T e )) will be produced.

[0064] First, the synchronous coordinate system dq-axis voltage equation can be expressed as follows when considering the steady state.

[0065] (3)

[0066] (4)

[0067] Here, is the extended back EMF component of the motor and can be defined as follows.

[0068] (5)

[0069] Using this formula, reactive power command It can be summarized as follows.

[0070] (6)

[0071] FIG. 5 shows the stator current (I S It represents the relationship between ) and the dq-axis current.

[0072] Above d-axis current in the equation It can be expressed as follows using the phase angle β between the stator current and the q-axis current.

[0073] (7)

[0074] Using this equation, the components related to back EMF can be rearranged into the following equation.

[0075] (8)

[0076] This formula is the above By substituting into the equation regarding, the reactive power command using saturated inductance can be obtained as follows.

[0077] (9)

[0078] At this time, the saturation inductance L(T) according to the output torque e ) is equal to the following equation.

[0079] Equation (10)

[0080] Here, L q is the q-axis inductance according to the q-axis current, and P represents the number of motor poles.

[0081] For the application of the saturation model, the synchronous coordinate system dq-axis current component is included as an argument, but in the case of scalar control, rotor position information is unknown, so the synchronous coordinate system variable, i.e., the dq-axis current component, cannot be used as an argument.

[0082] Therefore, the above equation can be expressed as follows by using the output torque instead of the q-axis current, which is a synchronous coordinate system variable.

[0083] (11)

[0084] Since the torque component of a synchronous motor is mostly occupied by the magnetic torque component, it is possible to approximate it by replacing the q-axis current with the torque component.

[0085] At this time, It is an inductance that reflects saturation according to output torque, and can be measured in advance and configured into a look-up table.

[0086] In addition, tanβ can be used by pre-calculating the current combination that minimizes the stator current according to the amount of torque and configuring it into a lookup table.

[0087] FIG. 6 is a schematic flowchart of a permanent magnet synchronous motor control method according to another preferred embodiment of the present invention.

[0088] The permanent magnet synchronous motor control method according to the present invention can be performed by a permanent magnet synchronous motor control device comprising one or more processors and memory.

[0089] Operating command voltage according to the motor's operating frequency command ( Calculate ) (S11).

[0090] Here, voltage fluctuations ( To add ), first calculate the saturation inductance (S12).

[0091] As previously discussed, saturation inductance can be calculated by estimating the output torque from the active power and using it as a factor after passing it through a low-pass filter.

[0092] By using saturated inductance, the voltage fluctuation ( ) can be calculated (S13).

[0093] Finally, the driving command voltage ( ) and voltage fluctuations( Adding ) to the final operating voltage command ( ) will be generated (S14).

[0094] By calculating the reactive power command using the inductance value that reflects saturation according to the output torque, there is an advantage of being able to achieve high-efficiency control close to the MTPA (Maximum Torque Per Ampere) operating point.

[0095]

[0096] FIG. 7 is a drawing for illustrating a computing environment including a computing device according to another preferred embodiment of the present invention.

[0097] In the illustrated embodiments, each component may have different functions and capabilities in addition to those described below, and may include additional components in addition to those not described below. The illustrated computing environment (60) may include a computing device (61) to perform the permanent magnet synchronous motor control method illustrated in FIG. 6. In one embodiment, the computing device (61) may be one or more components included in the permanent magnet synchronous motor control device illustrated in FIG. 1.

[0098] The computing device (61) includes at least one processor (62), a computer-readable storage medium (63), and a communication bus (65). The processor (62) may enable the computing device (61) to operate according to the exemplary embodiment described above. For example, the processor (62) may execute one or more programs (64) stored in the computer-readable storage medium (63). The one or more programs (64) may include one or more computer-executable instructions, and the computer-executable instructions may be configured to enable the computing device (61) to perform operations according to the exemplary embodiment when executed by the processor (62).

[0099] The communication bus (65) interconnects various other components of the computing device (61), including the processor (62) and the computer-readable storage medium (63).

[0100] The computing device (61) may also include one or more input / output interfaces (66) and one or more communication interfaces (67) that provide an interface for one or more input / output devices (68). The input / output interfaces (66) and the communication interfaces (67) are connected to a communication bus (65). The input / output devices (68) may be connected to other components of the computing device (61) through the input / output interfaces (66). An exemplary input / output device (68) may include input devices such as a pointing device (such as a mouse or trackpad), a keyboard, a touch input device (such as a touchpad or touchscreen), a voice or sound input device, various types of sensor devices and / or imaging devices, and / or output devices such as a display device, a printer, a speaker and / or a network card. An exemplary input / output device (68) may be included inside the computing device (61) as a component constituting the computing device (61), or it may be connected to the computing device (61) as a separate device distinct from the computing device (61).

[0101]

[0102] According to the permanent magnet synchronous motor control device and method of the present invention as described above, by controlling the motor using an inductance that reflects the saturation of the motor, it is possible to control the motor with high efficiency.

[0103]

[0104] The scope of protection of the present invention is not limited to the description and expression of the embodiments explicitly described above. Furthermore, it is added once again that the scope of protection of the present invention cannot be limited by obvious changes or substitutions in the technical field to which the present invention belongs.

Claims

1. Memory containing one or more instructions; and A processor that executes one or more instructions stored in the memory; comprising, The above processor is, In a reactive power control-based motor V / f control system, Calculate a voltage proportional to the motor operating frequency command and add the voltage fluctuation component based on reactive power control to generate a final voltage command, A permanent magnet synchronous motor control device characterized by the voltage fluctuation component based on the above reactive power control being calculated using a saturation inductance according to the output torque.

2. In Paragraph 1, A permanent magnet synchronous motor control device characterized by the processor estimating the output torque using the output power and operating speed command of the motor drive inverter.

3. In Paragraph 2, A permanent magnet synchronous motor control device characterized by the processor applying a low-pass filter (LPF) to the estimated output torque to calculate a saturation inductance according to the output torque.

4. In Paragraph 1, The above processor, according to the following mathematical formula (1), the output torque (T e Saturation inductance (L(T) according to ) e A permanent magnet synchronous motor control device characterized by calculating )). (1) Here, L q is the q-axis inductance according to the q-axis current, and I s is the motor stator current, and β is the angle formed by the stator current and the q-axis current, and P is the number of poles of the motor.

5. In Paragraph 4, The above processor is the q-axis current in the above mathematical formula (1). The above output torque (T e The output torque (T) above is approximated by the following mathematical formula (2) as ) e Saturation inductance (L(T) according to ) e A permanent magnet synchronous motor control device characterized by calculating )). (2) 6. In Paragraph 5, The above processor has a q-axis inductance (L) according to the output torque. q (T e A permanent magnet synchronous motor control device characterized by pre-calculating )) and the above tanβ and storing them in a look-up table.

7. In Paragraph 1, A permanent magnet synchronous motor control device characterized in that the above-mentioned motor is a surface-mounted permanent magnet synchronous motor (SPSM) or an interior permanent magnet synchronous motor (IPSM).

8. A V / f control unit that receives a motor operating frequency command and outputs a voltage command; A reactive power control unit that receives a variable including inductance as input and outputs a voltage fluctuation component; and A summer that sums the above voltage command and voltage fluctuation to output a final voltage command; is included. The above reactive power control unit is a permanent magnet synchronous motor control device that outputs the voltage fluctuation based on the saturation inductance according to the output torque.

9. A permanent magnet synchronous motor control method in a reactive power control-based motor V / f control system performed by a permanent magnet synchronous motor control device comprising one or more processors and memory: A step of calculating a voltage proportional to the motor operating frequency command; Step of calculating voltage fluctuations based on reactive power control; and A step of generating a final voltage command by adding a voltage proportional to the above motor operating frequency command and a voltage fluctuation component based on the above reactive power control; Includes, A permanent magnet synchronous motor control method characterized in that the voltage fluctuation component based on the above reactive power control is calculated using a saturation inductance according to the output torque.

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