A method for online automatic identification of servo motor

Abstract

The invention discloses a method for online automatic identification of a servo motor, which belongs to the technical field of servo motor calibration systems. It solves the problems of complicated steps, complicated operations and high costs for enterprises in servo motor identification and parameter calibration. The key points of the technical solution are to program the automatic identification method into a servo motor device, adopt one-key identification, and complete the identification and parameter calibration within a few minutes after calling the program. The method is fast, accurate and effective, and the identification effect is equivalent to that of professional technicians. It can significantly improve the efficiency of servo motor product inspection and calibration and after-sales service, and control the operating costs of the enterprise.

Description

Technical Field

[0001] The invention relates to the field of servo motor systems, and in particular to a method for online automatic identification of a servo motor. Background Art

[0002] Servo motor: It is an electric drive component that is controlled by a servo driver to achieve precise control of the position, speed, and torque of the associated machinery. Servo motors are mainly permanent magnet synchronous motors (PMSM), and are equipped with position encoders of different types and resolutions as needed.

[0003] Position encoder: a sensor that tracks the angle or position of the motor rotor. It is divided into photoelectric, magnetoelectric, resolver, and sine and cosine according to the sensing technology. It is divided into incremental, absolute, and analog according to the signal type. It is divided into multi-line, line-saving, and bus types according to the wiring method. The bus type is further divided into NRZ, Endat, Biss, SSI and other types according to the bus data protocol.

[0004] Servo motors have a wide range of application scenarios. Different application requirements, different motor design solutions and manufacturing processes, and different types of position encoders have led to a wide variety of servo motors. At present, the first calibration of new models of servo motors and servo drives is completed in the factory laboratory. The main reason is that the servo motor current loop is the bottom loop, which is the basis for the excellent performance of the outer speed loop and position loop, so it is very important to set the current loop parameters reasonably. The current loop control parameters are directly related to the internal model of the servo motor. The current loop PI parameters need to be set according to the electrical parameters of the servo motor (stator inductance, stator resistance, back electromotive force, pole pair number, rated current, peak current, etc.). In addition, the type and accuracy of the position encoder, the electrical angle zero position deviation, the rotor moment of inertia, etc. are related factors for the parameter transfer between the current loop and the speed loop, and they also need to be tested and calibrated in the factory. The above process needs to be repeated in the laboratory environment, with the help of professional test instruments and simulation debugging systems, and the motor drive professional engineers will try to adjust repeatedly. The whole adaptation process is time-consuming and laborious. At the application site, the servo drive can only use calibrated servo motors. If it is replaced with an uncalibrated servo motor on site, it will not be able to operate normally and reliably. Even if it can barely rotate, the control effect will be greatly reduced. The close coupling relationship between the servo drive and the servo motor increases the difficulty of servo drive manufacturing and inventory management, and after-sales maintenance is also greatly affected. For example, when the customer's original servo motor is damaged and stops, even if there is a ready-made similar servo motor, it cannot be replaced in time if it has not been calibrated, which reduces customer satisfaction. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and, at least to a certain extent, solve the technical problems in the related art. The calibration of the current loop control parameters of new types of servo motors is completed by professional technicians with the help of special instruments and equipment in a factory laboratory environment, and cannot be replaced and used immediately at the application site, which greatly limits the flexible configuration and after-sales maintenance of the servo drive system. We propose a current loop online identification method for a servo motor, which can well solve the problems of on-site adaptation and after-sales maintenance of these servo motors.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a method for online automatic identification of a servo motor, wherein an online automatic identification device is built into a servo driver, wherein the online automatic identification device starts to run after receiving a start command, and comprises the following steps:

[0007] Step 1: Obtain the motor category or optional manufacturing parameters input by the external user, select the corresponding encoder identification model according to the motor category and manufacturing parameters, and identify and calibrate the servo motor encoder;

[0008] Step 2: Identify the phase sequence and pole pair number of the servo motor;

[0009] Step 3: Intelligently adjust the current loop PI parameters;

[0010] Step 4: Calibrate the servo motor's moment of inertia and speed loop gain.

[0011] Preferably, step 1 includes dividing the position encoder into photoelectric, magnetoelectric, resolver, and sine and cosine according to the sensing technology, into incremental, absolute, and analog according to the signal type, and into multi-line, line-saving, and bus types according to the wiring method. The bus type is further divided into NRZ, Endat, Biss, and SSI types according to the bus data protocol, classifying the recognition models of the above types of encoders to form corresponding encoder recognition models, determining the specific encoder type according to the input information, and calling the corresponding encoder recognition model.

[0012] Preferably, step 2 includes open-loop control of the electric field scalar Vd, Vq values, electrical angle and step value, the electric field scalar Vd=K, Vq=0, the electrical angle is set to zero and stays for 2s, and the current encoder value is recorded; the electric field scalar Vd, Vq values ​​remain unchanged, the electrical angle increases by 60° step size and stays for 2s, and the current encoder value is recorded until 2 full circles are completed;

[0013] Evaluate and check whether the encoder resolution, pole pair number, electrical angle zero point offset, and power phase sequence are correct. If not, turn off PWM, display the alarm number, save the alarm record, and end. If correct, turn off PWM and record the encoder accuracy, pole pair number, power phase sequence, and electrical angle zero point offset information.

[0014] Preferably, step 3 includes testing the motor inductance and resistance according to the basic parameters of the motor, the major parameters of the motor, and the manufacturing parameters of the motor, and then setting the starting value, maximum value, Iq_ref test standard value, starting point of Kp and Ki, and adjustment step parameters of Kp and Ki of the current loop PI parameter identification respectively to ensure that the optimal PI parameters are within this range, and the identification measurement reasonably sets Iq_ref according to the rated current, gives a step input Iq_ref, observes the response curve of Iq_fbd, continuously adjusts the current loop Kp and Ki, and statistically analyzes the optimal Kp parameters and Ki parameters.

[0015] Preferably, step 3 includes starting this Iq response attempt, recording this Iq response curve, determining whether the Iq_fdb overshoot reaches the upper limit, if so, statistically analyzing the optimal Kp parameter, if not, determining whether Kp reaches the upper limit, if so, statistically analyzing the optimal Kp parameter, if otherwise, increasing the Kp parameter step and entering the Iq response attempt again until the Iq_fdb overshoot or Kp reaches the upper limit and statistically analyzing the optimal Kp parameter.

[0016] Preferably, step 3 includes starting this Iq response attempt, recording this Iq response curve, judging whether the Iq_fdb overshoot reaches the upper limit, if so, statistically analyzing the optimal Ki parameter, if not, judging whether Ki reaches the upper limit, if so, statistically analyzing the optimal Ki parameter, if not, increasing the Ki parameter step size and entering the Iq response attempt again, until the Iq_fdb overshoot or Ki reaches the upper limit and statistically analyzing the optimal Ki parameter.

[0017] Preferably, the calibration of the moment of inertia and the speed loop gain in step 4 includes: during calibration, reverse calculation is performed based on the time width of the motor rotor speed from zero to a preset speed in response to the Iq_fdb step, and the reference speed loop unit gain Knp0, Kni0 is obtained from this time constant, so as to calibrate the moment of inertia and the speed loop gain.

[0018] Compared with the background technology, the technical effects of the present invention are mainly reflected in the following aspects: The core invention of the present invention is to use an automatic identification test calibration method by deeply analyzing the principle model of each component inside the servo motor, simplifying the relatively complex motor calibration process that can only be operated by professional technicians into a one-key automatic identification calibration. We have programmed this method into the servo drive as an advanced function for users to call. The entire identification process does not require manual intervention and the identification time is 1 to 3 minutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the first part of the flow chart of the method in the embodiment;

[0020] Figure 2It is the second part of the flow chart of the method in the embodiment;

[0021] Figure 3 It is the third part of the flow chart of the method in the embodiment. DETAILED DESCRIPTION

[0022] The specific implementation modes of the present invention are further described below in conjunction with the accompanying drawings to make the technical solutions of the present invention easier to understand and grasp.

[0023] Example:

[0024] refer to Figure 1 , Figure 2 and Figure 3 As shown, a method for online automatic identification of a servo motor is provided, wherein an online automatic identification device is built into a servo driver, and the method is characterized in that the online automatic identification device starts to operate after receiving a start command, and comprises the following steps:

[0025] Step 1: Obtain the motor category or selectively input manufacturing parameters input by external users, select the corresponding encoder recognition model according to the motor category and manufacturing parameters, and identify and calibrate the servo motor encoder; classify the position encoder into photoelectric, magnetoelectric, resolver, sine and cosine according to the sensing technology, and into incremental, absolute, and analog according to the signal type; and into multi-line, line-saving, and bus types according to the wiring method. The bus type is further divided into NRZ, Endat, Biss, and SSI types according to the bus data protocol. The recognition models of the above types of encoders are classified to form corresponding encoder recognition models, and the specific encoder type is determined according to the input information and the corresponding encoder recognition model is called.

[0026] The servo motor encoder is a sensor that tracks the angle or position of the motor rotor. It is the core component of the servo motor. The resolution and installation angle deviation of the encoder are closely related to the performance of the motor. Therefore, the first step in the online identification of the servo motor is to identify and calibrate the motor position encoder.

[0027] Step 2: Identify the phase sequence and pole pair number of the servo motor. Open-loop control of the electric field scalar Vd, Vq value, electrical angle and step value, electric field scalar Vd = K, Vq = 0, K is a constant. The electrical angle is set to zero and stays for 2 seconds, and the current encoder value is recorded; the electric field scalar Vd, Vq values ​​remain unchanged, the electrical angle increases by 60° step size and stays for 2 seconds, and the current encoder value is recorded until 2 full circles are completed;

[0028] Evaluate and check whether the encoder resolution, pole pair number, electrical angle zero point offset, and power phase sequence are correct. If not, turn off PWM (pulse width modulation), display the alarm number, save the alarm record, and end. If correct, turn off PWM and record the encoder accuracy, pole pair number, power phase sequence, and electrical angle zero point offset information.

[0029] The power line phase sequence and pole pair number of servo motors from different manufacturers may be inconsistent. Even the power line and pole pair number of servo motors of different models from the same manufacturer may not be exactly the same. This difference cannot be distinguished by the naked eye. Therefore, through step 2, we complete the identification of the phase sequence and pole pair number of the servo motor. We analyze that by setting the scalar Vd and Vq of the motor in an open loop, rotating it in the predetermined electrical angle direction, and observing the rotation direction of the motor position encoder feedback to determine the positive and negative phase sequence of the power line. The principle of determining the number of motor pole pairs is the same. The servo motor rotation angle or number of turns is set in an open loop, and the actual movement angle or number of turns of the motor is observed to determine. The identification of the phase sequence and pole pair number must be performed after the encoder is identified.

[0030] Step 3: Intelligently adjust the current loop PI parameters. The performance of the servo motor is directly related to the current loop PI parameters. It is very important to set the current loop parameters reasonably. The winding inductance L, resistance R, back electromotive force, overload ratio, and pole pair number of different motors are difficult to be consistent. Even if the same design scheme uses different materials, such as iron core, enameled wire, magnetic steel sheet, etc., it will be reflected in the motor inductance L, resistance R and back electromotive force E. The benchmark of the PI parameters comes from these key parameters. We studied the transfer function relationship between them, tested the motor inductance and resistance according to the basic parameters of the motor, the major parameters of the motor, and the manufacturing parameters of the motor, and then set the starting value, maximum value, Iq_ref (test standard value), starting point of Kp and Ki, and adjustment step parameters of Kp and Ki for the current loop PI parameter identification respectively to ensure that the optimal PI parameters are within this range. The identification measurement reasonably sets Iq_ref according to the rated current, gives the step input Iq_ref, observes the response curve of Iq_fbd, continuously adjusts the current loop Kp and Ki, and statistically analyzes the optimal Kp and Ki parameters.

[0031] Start this Iq response attempt, record this Iq response curve, determine whether the Iq_fdb overshoot reaches the upper limit, if so, statistically analyze the optimal Kp parameter, if not, determine whether Kp reaches the upper limit, if so, statistically analyze the optimal Kp parameter, if not, increase the Kp parameter step and enter the Iq response attempt again until the Iq_fdb overshoot or Kp reaches the upper limit and statistically analyze the optimal Kp parameter.

[0032] Start this Iq response attempt, record this Iq response curve, determine whether the Iq_fdb overshoot reaches the upper limit, if so, statistically analyze the optimal Ki parameter, if not, determine whether Ki reaches the upper limit, if so, statistically analyze the optimal Ki parameter, if not, increase the Ki parameter step size and enter the Iq response attempt again until the Iq_fdb overshoot or Ki reaches the upper limit and then statistically analyze the optimal Ki parameter.

[0033] Step 4: Calibrate the servo motor's moment of inertia and speed loop gain. The calibration of the moment of inertia and speed loop gain includes: during calibration, the time width of the motor rotor speed from zero to the preset speed is calculated backwards according to the Iq_fdb step response, and the reference current loop unit gain Knp0 and Kni0 are obtained from this time constant to calibrate the moment of inertia and speed loop gain.

[0034] The moment of inertia of the optical axis of the servo motor is related to the unit gain of the speed loop Knp0 and Kni0. The servo motor is often connected to other mechanical transmission mechanisms in the application field. These mechanical structures can be converted into several or dozens of times the moment of inertia ratio. The Knp and Kni gains of the speed loop must be adjusted accordingly for different moment of inertia ratios. They can be simply equivalent to Knp = Jr * Knp0, Kni = Jr * Kni0, Jr is the moment of inertia ratio converted from all the machinery connected to the servo motor, and Knp0 and Kni0 are the unit gain of the speed loop. This unit gain is the basic parameter of the actual speed loop and gain, and there cannot be too much deviation, otherwise the speed loop parameter adaptation cannot achieve a perfect control effect.

[0035] This method does not matter which manufacturer the servo motor comes from or which type of position sensor is configured. It only requires the correct wiring between the drive controller and the servo motor and provides basic electrical parameters. In a few minutes, all electrical parameters of the servo motor, including the number of pole pairs, encoder resolution, mechanical zero point electrical angle offset value, current loop PI parameters, speed loop PI unit gain, etc., can be automatically identified.

[0036] Before the user starts the current loop online identification function, he must first make sure that the drive is in the disabled state, and then check whether the wiring of the servo motor to be identified (power line, position encoder line) is correct. After confirmation, the user can select the motor category or enter the basic motor electrical parameters through the drive panel menu to activate the online identification function. Once the function is started, it will be in automatic operation. No intervention is required during the entire process until the identification process is completed. After the identification is successfully completed, the parameters are automatically saved and take effect. The adaptation effect is comparable to that of professionals, and the detection efficiency is significantly better than the traditional calibration method. The user can confirm the identification effect by observing the current loop response curve through the host computer software.

[0037] This functional method can replace professionals in the factory to realize automatic calibration of newly added servo motors, and can also be used for calibration and correction when replacing unregistered servo motors at customer sites. It has strong operability.

[0038] At present, every time a new motor supplier is added or the raw materials are replaced, in order to achieve the best performance, the servo motor current loop calibration work must be repeated. As mentioned above, the current servo motor current loop calibration is completed by professional and technical personnel in a laboratory environment with the help of special detection instruments and simulation equipment. Enterprises have to pay a lot of manpower and time costs. In today's world where product technology iteration cycles are getting faster and faster, the traditional motor parameter calibration method needs to be upgraded and improved. On the other hand, due to the strong coupling relationship between the servo drive and the servo motor, if the servo drive or servo motor fails at the customer's application site, the original model product must be replaced. Once the original model is out of stock or discontinued, it must be replaced as a whole set to continue working. The after-sales maintenance cost is very high, resulting in a great waste of resources. The present invention aims to propose a new servo motor online automatic identification method, which has the characteristics of fast, accurate and effective, and the identification effect is equivalent to that of professional and technical personnel. It can significantly improve the efficiency of servo motor product detection calibration and after-sales service, and control the operating costs of the enterprise.

[0039] Of course, the above are only typical examples of the present invention. In addition, the present invention may also have many other specific implementations. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention.

Claims

1. A method for online automatic identification of a servo motor, wherein an online automatic identification device is built into a servo driver, wherein: The online automatic identification device starts to operate after receiving the start command, including the following steps: Step 1: Obtain the motor category or optional manufacturing parameters input by the external user, select the corresponding encoder recognition model according to the motor category and manufacturing parameters, and identify and calibrate the servo motor encoder; classify the position encoder into photoelectric, magnetoelectric, resolver, sine and cosine according to the sensing technology, incremental, absolute, and analog according to the signal type, multi-line, line-saving, and bus according to the wiring method, and the bus type is divided into NRZ, Endat, Biss, and SSI types according to the bus data protocol. Classify the recognition models of the above types of encoders to form corresponding encoder recognition models, determine the specific encoder type according to the input information, and call the corresponding encoder recognition model; Step 2: Identify the phase sequence and pole pair number of the servo motor; open-loop control of the electric field scalar Vd, Vq value, electrical angle and step value, the electric field scalar Vd = K, Vq = 0, K is used as a constant, the electrical angle is set to zero and stays for 2 seconds, and the current encoder value is recorded; the electric field scalar Vd, Vq values ​​remain unchanged, the electrical angle increases by 60° step size and stays for 2 seconds, and the current encoder value is recorded until 2 full circles are completed; Evaluate and check whether the encoder resolution, pole pair number, electrical angle zero point offset, and power phase sequence are correct. If not, turn off PWM, display the alarm number, save the alarm record, and end. If correct, turn off PWM and record the encoder accuracy, pole pair number, power phase sequence, and electrical angle zero point offset information. Step 3: Intelligently adjust the current loop PI parameters; including testing the motor inductance and resistance according to the basic motor parameters, motor category parameters, and motor manufacturing parameters, and then setting the starting value, maximum value, Iq_ref test standard value, Kp and Ki starting point, and Kp and Ki adjustment step parameters of the current loop PI parameter identification respectively, to ensure that the optimal PI parameters are within the interval between the starting value and the maximum value, and to identify and measure the reasonable setting of Iq_ref according to the rated current, give the step input Iq_ref, observe the response curve of Iq_fbd, continuously adjust the current loop Kp and Ki, and statistically analyze the optimal Kp and Ki parameters; Step 4: Calibrate the servo motor's moment of inertia and speed loop gain.

2. The method for online automatic identification of a servo motor according to claim 1, characterized in that: Step 3 includes starting this Iq response attempt, recording this Iq response curve, judging whether the Iq_fdb overshoot reaches the upper limit, if so, statistically analyzing the optimal Kp parameter, if not, judging whether Kp reaches the upper limit, if so, statistically analyzing the optimal Kp parameter, if not, increasing the Kp parameter step and entering the Iq response attempt again, until the Iq_fdb overshoot or Kp reaches the upper limit and statistically analyzing the optimal Kp parameter.

3. The method for online automatic identification of a servo motor according to claim 1, characterized in that: Step 3 includes starting this Iq response attempt, recording this Iq response curve, judging whether the Iq_fdb overshoot reaches the upper limit, if so, statistically analyzing the optimal Ki parameter, if not, judging whether Ki reaches the upper limit, if so, statistically analyzing the optimal Ki parameter, if not, increasing the Ki parameter step and entering the Iq response attempt again, until the Iq_fdb overshoot or Ki reaches the upper limit and statistically analyzing the optimal Ki parameter.

4. The method for online automatic identification of a servo motor according to claim 1, characterized in that: The calibration of the moment of inertia and speed loop gain in step 4 includes: during calibration, the time width of the motor rotor speed from zero to the preset speed is calculated backwards according to the Iq_fdb step response, and the reference speed loop unit gain Knp0 and Kni0 are obtained from this time constant, so as to calibrate the moment of inertia and speed loop gain.

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