Motor output power estimation method, motor output power control method and motor output power estimation device

Abstract

The invention relates to the technical field of motor control, and discloses a motor output power estimation method, control method and device, and the estimation method comprises the steps: obtaining a motor q-axis current, a damping coefficient, a rotating speed, a mechanical angular frequency, a permanent magnet flux linkage parameter and the number of pole pairs under a rotating coordinate system; estimating a motor output torque based on the motor q-axis current, the damping coefficient, the mechanical angular frequency, the permanent magnet flux linkage parameter and the number of pole pairs under the rotating coordinate system; and calculating motor output power according to the motor output torque and the rotating speed. According to the method, the output power of the motor can be accurately estimated only according to the output torque and the rotating speed of the motor without increasing extra hardware cost. The current output power is estimated by directly calculating the motor output torque, various losses of hardware and a motor body do not need to be considered, the accuracy of calculating the output power is improved, and the power estimation calculation process is simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a motor output power estimation method, a control method and a device. Background Art

[0002] In wind turbine applications, it is usually necessary to obtain the output power data of the motor to implement power protection and other functions during the operation of the motor. In mainstream applications, the motor output power data is generally obtained through intelligent power modules or by adding voltage and current sensors.

[0003] For the current mainstream technology, by obtaining voltage and current signals, the motor output power data is indirectly estimated through the principle P = 3*UI*cosθ or P = (Ud*Id+uq*Iq). However, there are still problems or defects, such as the need to increase hardware costs and controller volume, and the calculation is the motor input power rather than the output power, and the circuit loss and motor body loss are difficult to calculate directly, resulting in inaccurate estimation of the motor output power. Summary of the invention

[0004] In view of this, the present invention provides a motor output power estimation method, a control method and a device to solve the problem of how to improve the accuracy of motor output power estimation.

[0005] In the first aspect, the present invention provides a method for estimating the output power of a motor, comprising: obtaining the q-axis current, damping coefficient, speed and mechanical angular frequency, permanent magnet flux parameters, and pole pair number of the motor in a rotating coordinate system; estimating the output torque of the motor based on the q-axis current, damping coefficient and mechanical angular frequency, permanent magnet flux parameters, and pole pair number of the motor in the rotating coordinate system; and calculating the output power of the motor based on the output torque and speed of the motor.

[0006] The present invention does not increase the cost of additional hardware, and can estimate the motor output power more accurately based on the motor output torque and speed. That is, the motor output torque is directly calculated to estimate the current output power, and there is no need to consider the various losses of the hardware and the motor body, thereby improving the accuracy of calculating the output power and simplifying the power estimation calculation process.

[0007] In an optional implementation, the process of obtaining the damping coefficient includes: obtaining the damping coefficient by means of a dynamometer; or, obtaining the damping coefficient based on a torque-speed curve.

[0008] In an optional embodiment, the process of obtaining the damping coefficient based on the torque-speed curve includes: obtaining multiple motor torque-speed curves under different torques; selecting two reference points on each motor torque-speed curve; for each curve, based on the motor mechanical motion equation, using the load torque and motor mechanical angular frequency of the first reference point, and the load torque and motor mechanical angular frequency of the second reference point, obtaining the damping coefficient of each curve; adding the damping coefficients of each curve and taking the average value to obtain the damping coefficient of the motor.

[0009] In an optional implementation, the damping coefficient calculation formula for each curve is as follows:

[0010]

[0011] Wherein, B is the damping coefficient; TL1 and TL2 are the motor load torques at the first reference point and the second reference point, i.e., the motor output torque; ω m1 ,ω m2 are the motor mechanical angular frequencies of the first reference point and the second reference point respectively.

[0012] In an optional implementation, the motor output torque calculation formula is as follows:

[0013]

[0014] Among them, T L is the load torque, i.e. the motor output torque; n p is the number of motor pole pairs; f is the permanent magnet flux parameter of the motor; i q is the motor q-axis current; B is the motor damping coefficient; ω m is the motor mechanical angular frequency.

[0015] In a second aspect, the present invention provides a motor control method, comprising: estimating the motor output power based on the motor output power estimation method of the first aspect and any optional implementation manner thereof; obtaining a q-axis current reference value based on the motor output power using a power loop; obtaining a modulation wave based on the q-axis current reference value using a current loop and a voltage loop; and obtaining a drive signal of a converter in the motor using a space vector modulation method based on the modulation wave.

[0016] In a third aspect, the present invention provides a device for estimating motor output power, including: a parameter acquisition module for acquiring the motor q-axis current, damping coefficient, speed and mechanical angular frequency, permanent magnet flux parameters, and pole pair number in a rotating coordinate system; a first calculation module for estimating the motor output torque based on the motor q-axis current, damping coefficient and mechanical angular frequency, permanent magnet flux parameters, and pole pair number in the rotating coordinate system; and a second calculation module for calculating the motor output power based on the motor output torque and speed.

[0017] In a fourth aspect, the present invention provides a motor control device, comprising: a power estimation module, used to estimate the motor output power based on the motor output power estimation method of the first aspect and any optional implementation manner thereof; a power loop module, used to obtain a q-axis current reference value based on the motor output power using a power loop; a dual closed-loop module, used to obtain a modulation wave based on the q-axis current reference value using a current loop and a voltage loop; and a modulation module, used to obtain a drive signal of a converter in the motor based on the modulation wave using a space vector modulation method.

[0018] In a fifth aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, computer instructions being stored in the memory, and the processor executing the motor output power estimation method of the first aspect or any corresponding embodiment thereof and the motor control method of the second aspect by executing the computer instructions.

[0019] In a sixth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the motor output power estimation method of the first aspect or any corresponding embodiment thereof, and the motor control method of the second aspect.

[0020] In a seventh aspect, the present invention provides a computer program product, comprising computer instructions for causing a computer to execute the motor output power estimation method of the first aspect or any corresponding embodiment thereof, and the motor control method of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a schematic flow chart of a method for estimating motor output power according to an embodiment of the present invention;

[0023] Figure 2 is a control block diagram of a motor control method according to an embodiment of the present invention;

[0024] Figure 3 is a flow chart of calculating a damping coefficient according to an embodiment of the present invention;

[0025] Figure 4 is a flow chart of a motor control method according to an embodiment of the present invention;

[0026] Figure 5 is a comparison diagram of output power of a motor control method of a related art and an embodiment of the present invention;

[0027] Figure 6 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0029] According to an embodiment of the present invention, an embodiment of a method for estimating motor output power is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0030] In this embodiment, a method for estimating motor output power is provided. Figure 1 As shown, including:

[0031] Step S11: obtaining the motor q-axis current, damping coefficient, rotation speed and mechanical angular frequency, permanent magnet flux parameters, and pole pair number in the rotating coordinate system.

[0032] Step S12: Estimate the motor output torque based on the motor q-axis current, damping coefficient and mechanical angular frequency, permanent magnet flux parameters and pole pair number in the rotating coordinate system.

[0033] Specifically, the electromagnetic torque expression of the permanent magnet synchronous motor is known:

[0034]

[0035] Where, T e is the electromagnetic torque output by the motor; n p is the number of motor pole pairs; i d 、i q are the motor dq axis current respectively; L d , L q is the motor dq axis inductance; f is the permanent magnet flux parameter of the motor.

[0036] In the application of motors, the motors are generally salient-pole permanent magnet synchronous motors, but the salient pole ratio is very small and can be approximated as L d ≈L q , so the above formula can be simplified to:

[0037]

[0038] For the q-axis current i q , by driving the lower bridge sampling resistor to obtain the motor I A ,I B ,I C The three-phase current is obtained through Clark and Park transformation, as shown in the following example: Figure 2 shown.

[0039] The mechanical motion equation of permanent magnet synchronous motor is:

[0040]

[0041] Where J is the motor's moment of inertia; t is time; ω m is the mechanical angular frequency of the motor; T e is the electromagnetic torque output by the motor; T L is the load torque; B is the damping coefficient.

[0042] The electromagnetic torque expression shown in formula (2) can be obtained

[0043]

[0044] refer to Figure 2 , due to i q The acquisition is realized in the space vector modulation module. The modulation frequency is generally several KHz to tens of KHz, so i q The change in time t is much greater than the angular velocity ω m As time t changes, dω m / dt≈0.

[0045] Based on this, we simplify formula (4) and get

[0046]

[0047] Therefore, based on formula (5), the motor output torque is estimated using the q-axis current iq, damping coefficient B, mechanical angular frequency, pole pair number, and permanent magnet flux parameters.

[0048] Step S13: Calculate the motor output power according to the motor output torque and rotation speed.

[0049] The relationship between the motor output power and torque is known to be:

[0050]

[0051] Where P is the motor output power; n is the motor speed; where ω m =2π·n / 60.

[0052] Combining equation (5) and equation (6), the formula for calculating the motor output power is:

[0053]

[0054] Therefore, this embodiment does not increase the cost of additional hardware, and can estimate the motor output power more accurately based on the motor output torque and speed. That is, the motor output torque is directly calculated to estimate the current output power, without considering the various losses of the hardware and the motor body, thereby improving the accuracy of calculating the output power and simplifying the power estimation calculation process.

[0055] In some optional implementations, the process of obtaining the damping coefficient includes:

[0056] (1) In a laboratory environment, the damping coefficient is obtained using a dynamometer; (2) Alternatively, the damping coefficient is obtained based on the torque-speed curve.

[0057] For the second method, the process of obtaining the damping coefficient is based on the torque-speed curve, as shown in Figure 3 As shown, including:

[0058] Step S21: obtaining a plurality of motor torque-speed curves under different torques.

[0059] Specifically, in order to improve the accuracy of the damping coefficient, the dynamometer may be limited to different torques to obtain N motor torque-speed curves, and the damping coefficient corresponding to each curve may be calculated using steps S22 to S23.

[0060] Step S22: Select two reference points on each motor torque-speed curve.

[0061] Step S23: For each curve, based on the motor mechanical motion equation, using the load torque and the motor mechanical angular frequency of the first reference point, and the load torque and the motor mechanical angular frequency of the second reference point, obtain the damping coefficient of each curve.

[0062] Specifically, two reference points are selected on the curve, each of which has two parameters, namely, T L1 ,ω m1 、T L2 ,ω m2 , Substituting these four parameters into equation (3), we get equations (8) and (9).

[0063]

[0064] Subtracting equation (9) from equation (8) yields:

[0065]

[0066] In the speed curve, The damping coefficient is therefore:

[0067]

[0068] Step S24: Add the damping coefficients of each curve and calculate the average value to obtain the damping coefficient of the motor.

[0069] Specifically, after repeating step S22 and step S23 to calculate the damping coefficient of each curve, the damping coefficient of the motor is calculated as follows:

[0070]

[0071] In this embodiment, a motor control method is provided. Figure 4 As shown, including:

[0072] Step S31: Estimate the motor output power based on the motor output power estimation method of the above embodiment and any optional implementation manner thereof.

[0073] Step S32: Based on the motor output power, a q-axis current reference value is obtained using a power loop.

[0074] Step S33: Based on the q-axis current reference value, a modulated wave is obtained by using a current loop and a voltage loop.

[0075] Step S34: Based on the modulation wave, a space vector modulation method is used to obtain a drive signal for the converter in the motor.

[0076] Specifically, refer to Figure 2 The three-phase current of the motor is converted into the two-phase current in the stationary coordinate system through Clark transformation; the two-phase current in the stationary coordinate system is converted into the two-phase current in the rotating coordinate system through Park transformation. d 、i q , using i q , B, ω m , calculate the motor output power, calculate the motor speed based on the motor output power, perform PI control on the difference between the motor speed reference value and the motor speed, and obtain the q-axis current reference value. In the current loop, perform PI control on the q-axis current reference value and the d-axis current reference value to obtain the dq-axis voltage reference value, perform inverse Park transformation on the voltage reference value, and obtain the modulation wave.

[0077] This embodiment verifies the above method. When the motor output power is limited to 4000W, the output power-torque waveforms of the motor control method in the related art and the motor control method in this embodiment are as follows: Figure 5 As shown, Figure 5 In the motor control method of the related art, the motor output power has exceeded 4700W and reached the motor constant torque range, far exceeding the power limit point of 4000W. In the motor output power method of this embodiment, from Figure 5 It can be seen that the motor output power enters the constant power range at about 3900W, and as the output torque increases to the constant torque state, the output power limit point of this embodiment is more accurate.

[0078] In this embodiment, a motor output power estimation device and a motor control device are also provided, which are used to implement the above-mentioned embodiments and preferred implementation modes, and will not be repeated hereafter. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0079] In this embodiment, a motor output power estimation device is provided, comprising:

[0080] The parameter acquisition module is used to obtain the motor q-axis current, damping coefficient, speed and mechanical angular frequency, permanent magnet flux parameters, and pole pair number in the rotating coordinate system;

[0081] The first calculation module is used to estimate the motor output torque based on the motor q-axis current, damping coefficient and mechanical angular frequency, permanent magnet flux parameters and pole pair number in the rotating coordinate system;

[0082] The second calculation module is used to calculate the motor output power according to the motor output torque and rotation speed.

[0083] In this embodiment, a motor control device is provided, comprising:

[0084] A power estimation module, used for estimating the motor output power based on the motor output power estimation method of the above embodiment and any optional implementation manner thereof;

[0085] A power ring module is used to obtain a q-axis current reference value based on the motor output power using the power ring;

[0086] A dual closed-loop module is used to obtain a modulation wave based on a q-axis current reference value using a current loop and a voltage loop;

[0087] The modulation module is used to obtain a driving signal for a converter in the motor based on a modulation wave and using a space vector modulation method.

[0088] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0089] The motor output power estimation device and the motor control device in this embodiment are presented in the form of functional units, where the units refer to ASIC (Application Specific Integrated Circuit) circuits, processors and memories that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0090] An embodiment of the present invention further provides a computer device having the above-mentioned motor output power estimation device and motor control device.

[0091] See also Figure 6 , Figure 6 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Figure 6 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 6 A processor 10 is taken as an example.

[0092] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0093] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0094] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0095] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0096] The computer device further comprises a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0097] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0098] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0099] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for estimating motor output power, characterized in that: include: Obtain the motor q-axis current, damping coefficient, speed and mechanical angular frequency, permanent magnet flux parameters, and pole pair number in the rotating coordinate system; Estimate the motor output torque based on the motor q-axis current, damping coefficient and mechanical angular frequency, permanent magnet flux parameters and pole pair number in the rotating coordinate system; The motor output power is calculated according to the motor output torque and rotation speed.

2. The motor output power estimation method according to claim 1, characterized in that: The process of obtaining the damping coefficient includes: The damping coefficient can be obtained by using a dynamometer or based on the torque-speed curve.

3. The motor output power estimation method according to claim 2, characterized in that: The process of obtaining the damping coefficient based on the torque-speed curve includes: Under different torques, multiple motor torque-speed curves are obtained; Select two reference points on each motor torque-speed curve; For each curve, based on the mechanical motion equation of the motor, using the load torque and the motor mechanical angular frequency at the first reference point, and the load torque and the motor mechanical angular frequency at the second reference point, each damping coefficient is obtained; The damping coefficient of each curve is added and averaged to obtain the damping coefficient of the motor.

4. The motor output power estimation method according to claim 3, characterized in that: The damping coefficient of each curve is calculated as follows: Wherein, B is the damping coefficient; TL1 and TL2 are the motor load torques at the first reference point and the second reference point, i.e., the motor output torque; ω m1 ,ω m2 are the motor mechanical angular frequencies of the first reference point and the second reference point respectively.

5. The motor output power estimation method according to claim 1, characterized in that: The formula for calculating the motor output torque is as follows: Among them, T L is the load torque, i.e. the motor output torque; n p is the number of motor pole pairs; f is the permanent magnet flux parameter of the motor; i q is the motor q-axis current; B is the motor damping coefficient; ω m is the motor mechanical angular frequency.

6. A motor control method, characterized in that: include: Estimating the motor output power based on the motor output power estimation method according to any one of claims 1 to 5; Based on the motor output power, a q-axis current reference value is obtained using a power loop; Based on the q-axis current reference value, a modulated wave is obtained by using a current loop and a voltage loop; Based on the modulation wave, a driving signal of a converter in the motor is obtained by using a space vector modulation method.

7. A motor output power estimation device, characterized in that: include: The parameter acquisition module is used to obtain the motor q-axis current, damping coefficient, speed and mechanical angular frequency, permanent magnet flux parameters, and pole pair number in the rotating coordinate system; A first calculation module is used to estimate the motor output torque based on the motor q-axis current, damping coefficient and mechanical angular frequency, permanent magnet flux parameters and pole pair number in the rotating coordinate system; The second calculation module is used to calculate the motor output power according to the motor output torque and rotation speed.

8. A motor control device, characterized in that: include: A power estimation module, used for estimating the motor output power based on the motor output power estimation method according to any one of claims 1 to 5; A power ring module, used for obtaining a q-axis current reference value based on the motor output power by using the power ring; A dual closed-loop module, used to obtain a modulation wave based on the q-axis current reference value by using a current loop and a voltage loop; The modulation module is used to obtain a driving signal of a converter in the motor based on the modulation wave by using a space vector modulation method.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the motor output power estimation method described in any one of claims 1 to 5 and the motor control method described in claim 6 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the motor output power estimation method described in any one of claims 1 to 5 and the motor control method described in claim 6.

11. A computer program product, characterized in that It comprises computer instructions, wherein the computer instructions are used to enable a computer to execute the motor output power estimation method according to any one of claims 1 to 5 and the motor control method according to claim 6.

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