Constant torque calibration method for ECM motor

Abstract

Disclosed is a constant torque calibration method for an ECM motor. A new motor is used for replacing a motor to be replaced, and the new motor and the motor to be replaced are both constant torque control ECM motors. The method comprises the following steps: step A, on the basis of a torque value of a motor to be replaced, selecting m torque reference points and forming same into an expected torque value array LUT_X[m], wherein m is greater than or equal to 3; step B, on the basis of an actual torque of a new motor, locating m torque adjustment points in one-to-one correspondence with the toque reference points, and forming same into a new target torque value array LUT_Y[m]; and step C, receiving an original input target torque value T0, calling a linear interpolation module function to obtain a corresponding new target torque value T1, and enabling the new motor to carry out constant torque control at the new target torque value T1. By means of software algorithm processing, the constant torque performance of the new motor is controlled to be substantially consistent with a target reference of the motor to be replaced, test items for secondary motor development of users are reduced, the item development period is shortened, the research and development cost is reduced, and the calibration method is simple and effective.

Description

A constant torque calibration method for ECM motor Technical Field

[0001] The invention relates to a constant torque calibration method for an ECM motor. Background Art

[0002] After years of market application, the constant-torque-controlled ECM motors developed early by mainstream foreign air-conditioning manufacturers (such as Daikin and Carrier) need to be replaced with new motor manufacturers or new motor technologies (copper wire, aluminum wire, etc.). At this time, the performance of the new constant-torque-controlled ECM motor is required to be basically consistent with the performance of the original constant-torque-controlled ECM motor from the first supplier. However, the constant-torque-controlled ECM motors from different motor manufacturers have great differences due to various factors such as motor material properties, driver hardware, software algorithms, and production processes. In particular, for constant-torque application motors (mainstream applications in foreign HVAC equipment, based on current control), the tolerance requirements for each component are very high, and it is very difficult to achieve completely consistent constant-torque curves between the new and old motors.

[0003] Regarding the background technology of constant torque controlled ECM motors, reference may be made to the invention patent number CN201310518422 applied for by the applicant, titled "A method for controlling constant torque of an ECM motor," or the invention patent number CN201510079416 applied for by the applicant, titled "A method for controlling constant torque of an ECM motor," or the invention patent number CN201811334775 applied for by the applicant, titled "Constant torque control method for a permanent magnet synchronous motor based on position sensorless vector control," or the invention patent number CN202210365015 applied for by the applicant, titled "A method for controlling constant torque of an ECM motor applied for a fan system."

[0004] ECM motors use numerous constant-torque control algorithms. Differences in motor material properties, driver hardware, software algorithms, and production processes result in widely varying motor performance. Meeting customer requirements—replacing the original supplier's ECM motor with a new constant-torque-controlled ECM motor while ensuring essentially identical performance—became an urgent technical challenge.

[0005] At present, the common practice is to adopt the form of secondary development, that is, to redevelop a certain constant torque control ECM motor specifically for a certain fan system and simulate its constant torque control performance. This cannot achieve basic overlap with the constant torque performance of the original ECM motor, and the project development time is long, and the R&D cost increases.

[0006] Summary of the Invention

[0007] The present invention provides a constant torque calibration method for an ECM motor, which is used to solve the technical problem in the prior art of replacing an original ECM motor with a new ECM motor with constant torque control to ensure substantially consistent performance.

[0008] The technical solution of the present invention is achieved as follows:

[0009] A constant torque calibration method for an ECM motor is provided, wherein a new motor is used to replace a replaced motor, and both the new motor and the replaced motor are constant torque controlled ECM motors. The method is characterized by comprising the following steps:

[0010] Step A: Based on the torque value of the replaced motor, select m torque reference points and form an expected torque value array LUT_X[m], where m ≥ 3, the torque value of LUT_X[1] is the minimum torque value of the replaced motor, the torque value of LUT_X[max(m)] is the maximum torque value of the replaced motor, and m is an integer;

[0011] Step B: Based on the actual torque of the new motor, find m torque adjustment points. The torque values ​​of the torque adjustment points correspond to the torque values ​​of the torque reference points one by one, and form a new target torque value array LUT_Y[m];

[0012] Step C: Receive the original input target torque value T0, call the linear interpolation module function composed of the expected torque value array LUT_X[m] and the new target torque value array LUT_Y[m] to obtain the corresponding new torque target value T1, and make the new motor perform constant torque control with the new torque target value T1.

[0013] The linear interpolation module function described in step C above adopts a piecewise interpolation method, as follows:

[0014] Step C1, receiving an external input target torque T0, comparing T0 with the torque values ​​of each torque adjustment point, and finding the two torque adjustment points a and a+1 closest to T0, where the torque value of point a is less than T0 and less than the torque value of point a+1, and a is an integer;

[0015] Step C2: Call the linear interpolation module function composed of LUT_Y[a], LUT_Y[a+1], LUT_X[a] and LUT_X[a+1] to obtain the torque set point T1, and adjust the new motor to the torque set point T1.

[0016] The function of the linear interpolation module composed of LUT_Y[a], LUT_Y[a+1], LUT_X[a] and LUT_X[a+1] is T1=LUT_Y[a]+(LUT_Y[a+1]-LUT_Y[a]) / (LUT_X[a+1]-LUT_X[a]).

[0017] The above-mentioned step B includes the following specific steps: adjusting the torque value of each torque adjustment point through an experimental method, so that the torque value of the torque adjustment point and its corresponding torque reference point are the same, and forming a new target torque value array LUT_Y[m].

[0018] The aforementioned adjustment of the torque value at each torque adjustment point is specifically to adjust the torque value by adjusting the current and speed parameters of the point.

[0019] In the above step A, when m is an odd number, the torque value of LUT_X[median(m)] is set to half the rated torque value of the replaced motor, and median(m) refers to the middle value between 1 and m.

[0020] In the above-mentioned step A, among the m torque reference points, the difference in torque values ​​between two adjacent torque reference points is equal.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The constant torque calibration method of the motor comprises the following steps: step A, based on the torque value of the replaced motor, selecting m torque reference points and forming an expected torque value array LUT_X[m], wherein m≥3, the torque value of LUT_X[1] is the minimum torque value of the replaced motor, the torque value of LUT_X[max(m)] is the maximum torque value of the replaced motor, and m is an integer; step B, based on the actual torque of the new motor, finding m torque adjustment points, the torque values ​​of the torque adjustment points correspond one-to-one to the torque values ​​of the torque reference points, and forming a new target torque value array LUT_Y[m]; step C, receiving the original input target torque value T0, calling the linear interpolation module function composed of the expected torque value array LUT_X[m] and the new target torque value array LUT_Y[m] to obtain the corresponding new torque target value T1, so that the new motor performs constant torque control with the new torque target value T1. Through software algorithm processing, the new ECM motor with constant torque control can replace the original ECM motor with constant torque control, ensuring basically the same performance, reducing the number of test items for customers' binary motor development, shortening the project development cycle, and reducing manufacturing costs.

[0023] 2. When multiple loads are applied to the same constant torque controlled ECM motor, the original input target torque value T0 can be directly input for calibration. This way, only a small number of loads with application limit torque values ​​need to be examined, which greatly reduces the number of project development and saves R&D costs.

[0024] 3. Other advantages of the present invention are described in detail in the embodiment section. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a flow chart of a method for calibrating a constant torque of a motor according to an embodiment of the present invention;

[0026] FIG2 is a schematic diagram of the test of the present invention. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only 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 ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0028] As shown in FIG1 , this embodiment provides a method for calibrating a constant torque of an ECM motor. The method replaces a replaced motor with a new motor. Both the new motor and the replaced motor are constant torque controlled ECM motors. The method includes the following steps:

[0029] Step A: Based on the torque value of the replaced motor, select m torque reference points and form an expected torque value array LUT_X[m], where m ≥ 3, the torque value of LUT_X[1] is the minimum torque value of the replaced motor, and the torque value of LUT_X[max(m)] is the maximum torque value of the replaced motor. m is an integer, and max(m) is the maximum value of m.

[0030] Step B: Based on the actual torque of the new motor, find m torque adjustment points. The torque values ​​of the torque adjustment points correspond to the torque values ​​of the torque reference points one by one, and form a new target torque value array LUT_Y[m];

[0031] Step C: Receive the original input target torque value T0, call the linear interpolation module function composed of the expected torque value array LUT_X[m] and the new target torque value array LUT_Y[m] to obtain the corresponding new torque target value T1, and make the new motor perform constant torque control with the new torque target value T1.

[0032] The linear interpolation module function described in step C above adopts a piecewise interpolation method, as follows:

[0033] Step C1, receiving an external input target torque T0, comparing T0 with the torque values ​​of each torque adjustment point, and finding the two torque adjustment points a and a+1 closest to T0, where the torque value of point a is less than T0 and less than the torque value of point a+1;

[0034] Step C2: Call the linear interpolation module function composed of LUT_Y[a], LUT_Y[a+1], LUT_X[a] and LUT_X[a+1] to obtain the torque set point T1, and adjust the new motor to the torque set point T1.

[0035] The function of the linear interpolation module composed of LUT_Y[a], LUT_Y[a+1], LUT_X[a] and LUT_X[a+1] is T1=LUT_Y[a]+(LUT_Y[a+1]-LUT_Y[a]) / (LUT_X[a+1]-LUT_X[a]).

[0036] Step B includes the following specific steps: Adjusting the torque values ​​at each torque adjustment point through testing to ensure that the torque values ​​at each torque adjustment point and its corresponding torque reference point are the same, thereby forming a new target torque value array LUT_Y[m]. The testing method involves connecting a new motor to a dynamometer for testing. Using the expected torque value array LUT_X[m] as the basic data for the dynamometer, the new target torque value array LUT_Y[m] for the new motor is then determined, as shown in Figure 2.

[0037] The aforementioned adjustment of the torque value at each torque adjustment point is specifically to adjust the torque value by adjusting the current and speed parameters of the point.

[0038] In step A above, when m is an odd number, the torque value of LUT_X[median(m)] is set to half the rated torque value of the replaced motor, where median(m) refers to the middle value between 1 and m, and median(m) = (m+1) / 2.

[0039] The principle of this invention is to use a linear interpolation function to transform the complex torque calculation formula. That is, piecewise linear interpolation is used to calibrate the correspondence between the actual target torque of the new motor and the original torque of the replaced motor. The linear interpolation formula: The interpolation function is a linear polynomial (in layman's terms, a linear function) interpolation method, and the interpolation error at the interpolation node is zero. Geometrically speaking, the straight line between the two torque points is used to approximate the original torque function. Through software algorithm processing, the constant torque performance control of the new motor is basically consistent with the target benchmark of the replaced motor.

[0040] The principle of the software solution of the present invention is shown in FIG1 . S1: define the torque range expected by the replaced motor and represent it with an array LUT_X[m] (m>=3), and divide this torque range into 3 or more parts. The more parts, the better the accuracy. The reference torque points between the divided parts must include the minimum torque, maximum torque and half torque of the replaced motor. S2: the new motor (defined as its performance can basically coincide with the replaced motor) is tested at multiple data points to find the actual torque of m points. The value of the actual torque coincides with the torque of the expected torque point to obtain a new array, which is represented by LUT_Y[m], (m>=3); S3: Then the new motor inputs the original input target torque value T0, first determine which interval of LUT_Y[m] T0 belongs to, and then call the linear interpolation module function composed of LUT_X[m] and LUT_Y[m] to obtain the new torque target value T1, so that the new motor is controlled at constant torque with the new torque target value T1, and the expected original input target torque value T0 can be obtained.

[0041] As shown in Figure 1, the following example uses a 4-segment switching mode, where m = 5, to divide the torque value of the replaced motor into 4 intervals:

[0042] 1. General control parameter definition: define 2 arrays

[0043] LUT_X[5]={X1, X2, X3, X4, X5} represents the five expected reference torque points (based on the torque of the original model of the ECM motor that has been mass-produced and replaced by the customer): 1%*Tmax, 30%*Tmax, 50%*Tmax, 70%*Tmax, 100%*Tmax, which must include the maximum torque value and the minimum torque value. Tmax usually refers to the rated torque of the replaced motor.

[0044] LUT_Y[5]={Y1, Y2, Y3, Y4, Y5} represents the new target torque value after the new motor meets the above 5 reference torque points. Slowly adjust LUT_Y[5] through experimental methods to ensure that the actual torque curves of LUT_Y[5] and LUT_X[5] are consistent, the actual torque curves of LUT_Y[4] and LUT_X[4] are consistent, the actual torque curves of LUT_Y[,3] and LUT_X[3] are consistent, the actual torque curves of LUT_Y[,2] and LUT_X[2] are consistent, and the actual torque curves of LUT_Y[1] and LUT_X[1] are consistent. Then record the 5 new target torque values ​​and fill them into LUT_Y[5].

[0045] 2. Piecewise linear interpolation: The original input target torque T0 setting point will be in multiple intervals between Y1 and Y5. Determine which interval the target torque T0 falls into (divided into four intervals, Y1-Y2, Y2-Y3, Y3-Y4, and Y4-Y5. Each interval is roughly divided into equal parts according to the torque range) and select the interval for linear interpolation.

[0046] The interpolation formula for the first interval is Y=Y1+(Y2-Y1) / (X2-X1); T0 belongs to the interval [Y1, Y2]

[0047] The interpolation formula for the second interval is Y=Y2+(Y3-Y2) / (X3-X2); T0 belongs to the interval [Y2, Y3]

[0048] The interpolation formula for the third interval is Y=Y3+(Y4-Y3) / (X4-X3); T0 belongs to the interval [Y3, Y4]

[0049] The interpolation formula for the fourth interval is Y=Y4+(Y5-Y4) / (X5-X4); T0 belongs to the interval [Y4, Y5]

[0050] 3. After linear interpolation, the new target torque value T1 is obtained. The new motor is controlled at constant torque with the new torque target value T1, which is consistent with the original input torque value T0 expected by the replaced motor. The target value obtained by multi-segment interpolation is more accurate than that obtained by single-segment interpolation.

[0051] The constant torque calibration method for the ECM motor described in this embodiment is simple to calibrate and has good effects, which greatly saves the cost and time of secondary development. It better solves the problem that it is difficult to achieve basically consistent performance when a new ECM motor with constant torque control replaces an existing ECM motor with constant torque control on the market.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A constant torque calibration method for an ECM motor, wherein a new motor is used to replace the replaced motor, and both the new motor and the replaced motor are constant torque controlled ECM motors, characterized in that: The following steps are involved: Step A: Based on the torque value of the replaced motor, select m torque reference points and form an expected torque value array LUT_X[m], where m ≥ 3, the torque value of LUT_X[1] is the minimum torque value of the replaced motor, and the torque value of LUT_X[max(m)] is the maximum torque value of the replaced motor. m is an integer, and max(m) is the maximum value of m. Step B: Based on the actual torque of the new motor, find m torque adjustment points. The torque values of the torque adjustment points correspond to the torque values of the torque reference points one by one, and form a new target torque value array LUT_Y[m]; Step C: Receive the original input target torque value T0, call the linear interpolation module function composed of the expected torque value array LUT_X[m] and the new target torque value array LUT_Y[m] to obtain the corresponding new torque target value T1, and make the new motor perform constant torque control with the new torque target value T1.

2. The constant torque calibration method of an ECM motor according to claim 1, characterized in that: The linear interpolation module function described in step C adopts a piecewise interpolation method, which is as follows: Step C1, receiving an external input target torque T0, comparing T0 with the torque values of each torque adjustment point, and finding the two torque adjustment points a and a+1 closest to T0, where the torque value of point a is less than T0 and less than the torque value of point a+1, and a is an integer; Step C2: Call the linear interpolation module function composed of LUT_Y[a], LUT_Y[a+1], LUT_X[a] and LUT_X[a+1] to obtain the torque set point T1, and adjust the new motor to the torque set point T1.

3. The constant torque calibration method for an ECM motor according to claim 2, characterized in that: The linear interpolation module function composed of LUT_Y[a], LUT_Y[a+1], LUT_X[a] and LUT_X[a+1] is T1=LUT_Y[a]+(LUT_Y[a+1]-LUT_Y[a]) / (LUT_X[a+1]-LUT_X[a]).

4. The constant torque calibration method of an ECM motor according to claim 3, characterized in that: The step B includes the following specific steps: adjusting the torque value of each torque adjustment point by an experimental method, so that the torque values of the torque adjustment point and its corresponding torque reference point are the same, and forming a new target torque value array LUT_Y[m].

5. The constant torque calibration method for an ECM motor according to claim 4, characterized in that: The adjusting of the torque value at each torque adjustment point is specifically adjusting the torque value by adjusting the current and speed parameters of the point.

6. The constant torque calibration method for an ECM motor according to any one of claims 1 to 5, characterized in that: In step A, when m is an odd number, the torque value of LUT_X[median(m)] is set to half the rated torque value of the replaced motor, and median(m) refers to the middle value between 1 and m.

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