Motor control method, device and computer readable storage medium

Abstract

The application discloses a motor control method, device and computer readable storage medium. The method comprises the following steps: determining a speed given value, a speed actual value and an integral link output value of a frequency converter for a speed control process of a motor; judging whether the motor is in a zero-speed running state based on the speed given value, the speed actual value and the integral link output value; and clearing the integral link output value when it is judged that the motor is in the zero-speed running state. The application realizes accurate judgment of the zero-speed running state of the motor, determines the essential reason why the motor still rotates when the zero-speed running state is determined, and can avoid undesired rotation of the motor in the zero-speed running state by clearing the integral link output value.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of motor technology, and in particular to a motor control method, device and computer-readable storage medium. Background Technology

[0002] Motor control refers to the control of a motor's starting, acceleration, operation, deceleration, and stopping. Depending on the type of motor and its application, motor control has different requirements and objectives. Through motor control, the goals of rapid motor start-up, rapid response, high efficiency, high torque output, and high overload capacity can be achieved.

[0003] Both AC and DC speed control devices require motors to operate at zero speed at certain times. To achieve this, two common motor control methods are used. In Method 1, the inverter directly issues a stop command (ON / OFF1 = 0). With the arrival of the falling edge of the command, the running motor decelerates to zero along the deceleration ramp. The inverter then cancels the trigger pulse and ceases control of the motor. In Method 2, the inverter's run command remains unchanged (ON / OFF1 = 1), but the speed setpoint is set to zero. The running motor also decelerates to zero along the deceleration ramp. Summary of the Invention

[0004] The present invention provides a motor control method, an apparatus, and a computer-readable storage medium.

[0005] In a first aspect, embodiments of the present invention provide a motor control method, comprising:

[0006] Determine the setpoint speed of the motor, the actual speed, and the output value of the integral component of the inverter for the speed control process of the motor;

[0007] Based on the given speed value, the actual speed value, and the output value of the integral element, determine whether the motor is in a zero-speed running state.

[0008] When the motor is determined to be running at zero speed, the output value of the integral circuit is cleared to zero.

[0009] As can be seen, the embodiments of the present invention can accurately determine whether the motor is in a zero-speed operating state based on the speed setpoint, the actual speed value, and the output value of the integral stage. Moreover, the embodiments of the present invention identify the root cause of the motor still rotating slowly when in a zero-speed operating state, and by clearing the output value of the integral stage, the unwanted motor rotation in the zero-speed operating state can be eliminated.

[0010] In an exemplary embodiment, determining whether the motor is in a zero-speed operating state based on the speed setpoint, the actual speed value, and the output value of the integral element includes:

[0011] When the absolute value of the speed setpoint is less than a preset first threshold, the absolute value of the actual speed is less than a preset second threshold, and the absolute value of the output value of the integral element is less than a preset third threshold, the motor is determined to be in a zero-speed operating state; wherein the first threshold and the second threshold are respectively related to the speed reference value of the motor, the third threshold is related to the torque reference value of the motor, and the first quotient of the first threshold divided by the speed reference value of the motor and the second quotient of the second threshold divided by the speed reference value of the motor are respectively less than or equal to 0.01.

[0012] Therefore, the embodiments of the present invention can accurately determine whether the motor is in a zero-speed running state based on the threshold value judgment method.

[0013] In an exemplary embodiment, the first threshold value is the product of A% and the speed reference value, the second threshold value is the product of B% and the speed reference value, and the third threshold value is the product of C% and the torque reference value, wherein the value of A ranges from [0, 0.04]; the value of B ranges from [0, 0.08]; and the value of C ranges from [1, 8].

[0014] As can be seen, the embodiments of the present invention propose preferred numerical ranges for each threshold value.

[0015] In an exemplary embodiment, clearing the output value of the integral stage includes:

[0016] When the duration of the motor running at zero speed is greater than or equal to a predetermined delay time, the output value of the integral element is cleared to zero.

[0017] As can be seen, the embodiments of the present invention can avoid erroneous state determination by comparing the duration of the zero-speed operation state.

[0018] In an exemplary embodiment, clearing the output value of the integral element includes:

[0019] By setting the inverter control word, an enable command for the non-enabled speed controller is given within a predetermined time period.

[0020] Therefore, the embodiments of the present invention achieve rapid control by setting the inverter control word.

[0021] In an exemplary embodiment, the predetermined time period is longer than one sampling period of the speed control process.

[0022] As can be seen, the predetermined time period in the embodiment of the present invention is longer than the sampling period, which ensures that the process of eliminating the output value of the integral link is performed at least once during the control process, thus ensuring the reliability of the operation of clearing the output value of the integral link to zero.

[0023] In an exemplary embodiment, clearing the output value of the integral element includes:

[0024] Based on the speed setpoint, the actual speed value, and the output value of the integral element, a positive pulse signal with a duration of the predetermined time period is generated;

[0025] The positive pulse signal is inverted into a negative pulse signal;

[0026] The negative pulse signal is provided to the control bit in the inverter control word for enabling or disabling the speed controller enable command.

[0027] Therefore, the embodiments of the present invention can conveniently eliminate the output value of the integral stage through pulse signal processing.

[0028] In a second aspect, embodiments of the present invention provide a motor control device, comprising:

[0029] The determination module is configured to determine the speed setpoint of the motor, the actual speed value, and the output value of the integral element of the inverter for the speed control process of the motor;

[0030] The judgment module is configured to determine whether the motor is in a zero-speed running state based on the speed setpoint, the actual speed value, and the output value of the integral element.

[0031] The elimination module is configured to clear the output value of the integral element to zero when it is determined that the motor is in a zero-speed running state.

[0032] As can be seen, the embodiments of the present invention can accurately determine whether the motor is in a zero-speed operating state based on the speed setpoint, the actual speed value, and the output value of the integral stage. Moreover, the embodiments of the present invention identify the root cause of the motor still rotating slowly when in a zero-speed operating state, and by clearing the output value of the integral stage, the unwanted motor rotation in the zero-speed operating state can be eliminated.

[0033] In an exemplary embodiment, the judgment module is configured to determine that the motor is in a zero-speed operating state when the absolute value of the speed setpoint is less than a preset first threshold, the absolute value of the actual speed is less than a preset second threshold, and the absolute value of the output value of the integral element is less than a preset third threshold; wherein the first threshold and the second threshold are respectively related to the speed reference value of the motor, the third threshold is related to the torque reference value of the motor, and the first quotient of the first threshold divided by the speed reference value of the motor and the second quotient of the second threshold divided by the speed reference value of the motor are respectively less than or equal to 0.01.

[0034] Therefore, the embodiments of the present invention can accurately determine whether the motor is in a zero-speed running state based on the threshold value judgment method.

[0035] In an exemplary embodiment, the first threshold value is the product of A% and the speed reference value, the second threshold value is the product of B% and the speed reference value, and the third threshold value is the product of C% and the torque reference value, wherein the value of A ranges from [0, 0.04]; the value of B ranges from [0, 0.08]; and the value of C ranges from [1, 8].

[0036] As can be seen, the embodiments of the present invention propose preferred numerical ranges for each threshold value.

[0037] In an exemplary embodiment, the elimination module is configured to clear the output value of the integral element to zero when the duration of the motor being in a zero-speed operating state is greater than or equal to a predetermined delay time.

[0038] As can be seen, the embodiments of the present invention can avoid erroneous state determination by comparing the duration of the zero-speed operation state.

[0039] In an exemplary embodiment, the elimination module is configured to disable the speed controller enable command during the predetermined time period by setting the inverter control word.

[0040] Therefore, the embodiments of the present invention achieve rapid control by setting the inverter control word.

[0041] In an exemplary embodiment, the predetermined time period is longer than one sampling period of the speed control process.

[0042] As can be seen, the predetermined time period in the embodiment of the present invention is longer than the sampling period, which ensures that the process of eliminating the output value of the integral link is performed at least once during the control process, thus ensuring the reliability of the operation of clearing the output value of the integral link to zero.

[0043] In an exemplary embodiment, the elimination module is configured to generate a positive pulse signal with a duration of the predetermined time period based on the speed setpoint, the actual speed value, and the output value of the integral element; to invert the positive pulse signal into a negative pulse signal; and to provide the negative pulse signal to a control bit in the inverter control word for enabling or disabling the speed controller enable command.

[0044] Therefore, the embodiments of the present invention can conveniently eliminate the output value of the integral stage through pulse signal processing.

[0045] In an exemplary embodiment, the elimination module includes:

[0046] The first absolute value unit is configured to output the first absolute value of the first quotient of the speed setpoint divided by the speed reference value of the motor.

[0047] The second absolute value unit is configured to output the second absolute value of the second quotient of the actual speed value divided by the speed reference value;

[0048] The third absolute value unit is configured to output the third absolute value of the third quotient of the output value of the integral element divided by the torque reference value of the motor;

[0049] The first numerical comparator unit is configured to output a first logic value whose absolute value is less than a first threshold value;

[0050] The second numerical comparator unit is configured to output a second logic value whose second absolute value is less than a second threshold value;

[0051] The second numerical comparator unit is configured to output a third logic value whose absolute value is less than a third threshold value;

[0052] AND gate logic circuits perform a logical AND operation on a first logic value, a second logic value, and a third logic value to produce a logical AND operation result;

[0053] A power-on delay timer is used to filter the result of the logical AND operation within a delay time.

[0054] A positive pulse generator is used to generate a positive pulse signal for a predetermined time period based on the filtered result of the logical AND operation.

[0055] A converter for converting the positive pulse signal into the negative pulse signal, wherein the negative pulse signal is provided to the control bit.

[0056] As can be seen, the preferred structure of the elimination module proposed in the embodiments of the present invention can flexibly eliminate the output value of the integral stage.

[0057] Thirdly, embodiments of the present invention provide a motor control device, comprising:

[0058] Memory, configured to store computer-readable code;

[0059] The processor is configured to invoke the computer-readable code to execute the motor control method as described in any of the preceding items.

[0060] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer-readable instructions, which, when executed by a processor, cause the processor to perform the motor control method as described in any of the preceding claims.

[0061] Fifthly, embodiments of the present invention provide a computer program product, characterized in that the computer program product is tangibly stored on a computer-readable storage medium and includes computer-readable instructions, which, when executed, cause a processor to perform the motor control method as described in any of the preceding claims. Attached Figure Description

[0062] Figure 1 This is an exemplary flowchart of the motor control method according to an embodiment of the present invention.

[0063] Figure 2 This is an exemplary logic diagram of motor speed control according to an embodiment of the present invention.

[0064] Figure 3 This is an exemplary schematic diagram of motor speed control according to an embodiment of the present invention.

[0065] Figure 4 This is an exemplary schematic diagram illustrating how to determine whether a motor is in a zero-speed operating state according to an embodiment of the present invention.

[0066] Figure 5 This is an exemplary schematic diagram of the execution speed control output according to an embodiment of the present invention.

[0067] Figure 6 This is a schematic diagram of an exemplary waveform for the speed controller enable command according to an embodiment of the present invention.

[0068] Figure 7 This is a schematic diagram illustrating an exemplary process for execution speed control according to an embodiment of the present invention.

[0069] Figure 8 This is a structural diagram of the motor control device according to an embodiment of the present invention.

[0070] Figure 9 This is another exemplary structural diagram of the motor control device according to an embodiment of the present invention.

[0071] The accompanying figure is labeled as follows:

[0072]

[0073] Detailed Implementation

[0074] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed merely to enable those skilled in the art to better understand and implement the subject matter described herein, and are not intended to limit the scope, applicability, or examples set forth in the claims. The function and arrangement of the elements discussed may be changed without departing from the scope of the embodiments of the invention. Various processes or components may be omitted, substituted, or added as needed in the various examples. For example, the described methods may be performed in a different order than described, and steps may be added, omitted, or combined. Furthermore, features described in some examples may be combined in other examples.

[0075] As used herein, the term "comprising" and its variations are open terms meaning "including but not limited to". The term "based on" means "at least partially based on". The terms "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other definitions, whether explicit or implicit, may be included below. Unless explicitly indicated by the context, the definition of a term shall remain consistent throughout the specification.

[0076] As mentioned above, two common motor control methods are currently used to achieve zero-speed operation of the motor. One method typically utilizes a frequency converter (VDC) to drive the motor. A VDC is a control device that uses the switching action of power semiconductor devices to convert mains frequency power into electrical energy of another frequency. VDCs mainly employ an AC-DC-AC method (VVVF frequency conversion or vector control frequency conversion), first converting the mains frequency AC power into DC power through a rectifier, and then converting the DC power into AC power with controllable frequency and voltage to supply the motor. A VDC generally includes components such as rectification, an intermediate DC link, inversion, and control. VDCs can use insulated-gate bipolar transistors (IGBTs) to convert DC power into AC power.

[0077] In Method 1: The frequency converter directly issues a stop command (ON / OFF1 = 0). As the falling edge of the command arrives, the running motor will decelerate to zero along the deceleration ramp. Subsequently, the frequency converter cancels the trigger pulse and no longer controls the motor.

[0078] In Method 2: The inverter's operating command remains unchanged (ON / OFF1 = 1), but the speed setpoint is set to zero, and the running motor also decelerates to zero along the deceleration ramp.

[0079] The applicant, after research, found that Method 1 has the following advantages: no current flows through the inverter or thyristor after stopping, allowing sufficient time for the IGBT or thyristor to dissipate heat. The disadvantages of Method 1 include: for asynchronous motors, excitation is required after each re-enabling. Since motor operation can only be controlled after excitation, Method 1 results in insensitive inching operation. Method 2 has the following advantages: asynchronous motors do not require re-excitation upon restarting, improving operational sensitivity. The disadvantages of Method 2 include: when the motor decelerates to zero speed, current still flows through the inverter's IGBT or thyristor because the trigger pulse remains active. Especially at zero speed, commutation between the IGBT or thyristor is very slow, causing a significant increase in the temperature of the IGBT or thyristor.

[0080] Currently, the conventional practice in this field is to use Method 2 to stop the motor to improve maneuverability. Method 2 typically solves the problem of insensitive inching operation. However, the applicant has also discovered unexpected problems when using Method 2. Specifically, after the motor decelerates to zero, it continues to rotate at a low speed (even though the speed setpoint remains zero), leading to various defects, such as the inability to position the load. When the speed setpoint is zero but the motor continues to rotate slowly, those skilled in the art are often confused because they do not know the cause of this phenomenon, and usually have to use Method 1 to stop the motor. However, Method 1 requires repeated motor excitation, resulting in insensitive operation. Operators must repeat the operation to achieve the required load positioning, which consumes a significant amount of operation time and reduces productivity.

[0081] The following section will analyze the cause of this phenomenon (the motor rotates slowly when the speed is given as zero) and find a way to eliminate it.

[0082] For ease of description, we will use an application scenario as an example below.

[0083] The leveling and slitting line is used for the subsequent processing of thin plates produced by the continuous casting and rolling production line. This involves leveling large steel coils and then cutting them into smaller coils for user convenience. The leveling and slitting line mainly consists of an uncoiler, a straightener, a leveler, a slitting shear, and a coiler. Since the main purpose of this invention is not to describe the leveling and slitting line, the functions of each piece of equipment will not be elaborated here; instead, attention will be focused on the coiler. The coiler has a wedge-shaped groove containing a hydraulic clamping device. To wind the steel strip onto the coiling roller, the strip head needs to be clamped into the wedge-shaped groove first. Therefore, the coiling roller needs to be moved by jogging to allow the strip head to quickly enter the wedge-shaped groove.

[0084] 1. Considering that it is a jog operation, the commissioning engineer first used method one (such as using the JOG command) to achieve this function. However, since the motor power is 1200KW and the excitation time is more than 2.5s, the jog command has a large delay, which makes the operation insensitive and unable to stop accurately. The operator has to operate repeatedly, resulting in a lot of wasted time.

[0085] 2. To avoid the problem of insensitive operation, Method Two can be tried, which involves releasing or locking the speed setpoint to achieve jogging operation without canceling the enable command. Method Two solves the problem of insensitive operation, but an unexpected problem arises: in some cases, when the motor decelerates to zero speed, even if the speed setpoint is zero, the motor still rotates at a very low speed. Oscilloscope observation shows that the motor's rotation speed is approximately 1 pulse / s. Although this speed is slow, the linear velocity on the surface of the take-up roller is still significant due to its large diameter. Because the rotation cannot be completely stopped, the steel strip head cannot smoothly enter the wedge groove, thus defeating the purpose of using Method Two.

[0086] Taking a certain model of frequency converter using a proportional-integral (PI) control process as an example, for instance, the speed regulator used in this frequency converter is a PI regulator. When the actual speed drops to zero, the input / output parameters of the speed controller of the frequency converter are observed, and the results are as follows: (1) Speed ​​setpoint r1438 = 0; (2) Actual speed value r1445 = 0; (3) Proportional link speed deviation r0064 = 0; (4) Integral link speed deviation r1454 = 0; (5) Proportional link output value r1481 = 0; (6) Integral link output value r1482 is approximately 2.4-4%. Here, considering the expression habits in industrial settings, the specific values ​​of each input / output parameter are the result of comparison with the reference values ​​of their respective motor types. For example, r1482 is the ratio of the torque value output by the integral link to the reference torque value of the motor. For example, when r1482 equals 3%, the output value of the integral link expressed as torque value is the product of the reference torque value and 3%.

[0087] After studying the input / output parameters, the applicant found that the reasons for the zero speed setpoint and slow motor rotation include at least: (1) the characteristics of the integral algorithm; and (2) the data processing problem of the encoder feedback channel.

[0088] The two reasons will be explained in detail below.

[0089] 1. Characteristics of the integration algorithm

[0090] For horizontal loads, when the speed is zero, the load does not actually require the motor to continue outputting torque. However, observation reveals that the output of the integral term is not zero. This is due to the inherent characteristics of the integral algorithm. For the output of the integral term to become zero, the speed needs to have a reverse overshoot and maintain it for a suitable time, but this is difficult to achieve. Therefore, the integral term will always have a relatively small output value, typically 2.4% to 4% in a winding machine scenario. Although this output value, expressed as a percentage, seems small, when the motor power is high, such as the winding machine motor's torque reference value P2003 reaching 18800 Nm, the actual output torque of this value is between 2.4%*18800 and 4%*18800 Nm, or between 451 Nm and 752 Nm. When this output torque exceeds the system friction torque, the winding roller will rotate.

[0091] 2. Data processing of encoder feedback channel

[0092] The winding machine motor uses an HTL encoder with 1024 pulses / revolution. When the minimum pulse feedback rate is 1 pulse / s, the actual motor speed corresponding to this minimum pulse feedback rate is 1 / 1024*60 = 0.059 rpm. At such a low speed, the calculated result after processing by the encoder feedback channel is zero. Therefore, although the motor is rotating slowly, the actual speed r1445 remains zero, resulting in the integral speed deviation r1454 remaining zero. This means that the integral speed deviation r1454 cannot reduce the torque output r1482 of the speed controller's integral element. From the above analysis, it is clear that the slow rotation of the motor cannot be eliminated by relying on encoder speed feedback.

[0093] Therefore, the key lies in how to promptly eliminate the torque output r1482 of the integral term after the motor reaches zero-speed operation. At this point, two sub-tasks need to be completed: first, determine whether the motor is already at zero-speed operation; second, eliminate the torque output of the integral term.

[0094] Figure 1 This is an exemplary flowchart of the motor control method according to an embodiment of the present invention. Figure 1The method shown is preferably executed by a frequency converter of the drive motor. The speed controller in the frequency converter can be proportional-integral (PI) regulation or proportional-integral-derivative (PID) regulation. Figure 1 The method shown is particularly suitable for motors with large output torque, such as motors in zero-speed operation where the actual output torque of the integral element in the motor speed control process is greater than the system friction torque.

[0095] like Figure 1 As shown, the motor control method 100 includes:

[0096] Step 101: Determine the setpoint speed of the motor, the actual speed, and the output value of the integral component of the frequency converter for the motor speed control process.

[0097] Here, the motor speed setpoint can be obtained from the PLC, which acts as the host computer. The actual speed value can be determined by the frequency converter itself or read from the motor's encoder. The frequency converter, through its own speed controller, can determine the output value of the integral stage.

[0098] Step 102: Based on the speed setpoint, the actual speed value, and the output value of the integral element, determine whether the motor is in a zero-speed running state.

[0099] For example, based on the speed setpoint, actual speed, and integral output, it can be determined whether the motor has transitioned from a non-zero speed operating state to a zero speed operating state. Here, zero speed operating state means that both the speed setpoint and actual speed are zero or approximately zero, the integral output is not zero, the inverter's operating command is enabled, and the motor is still under the inverter's control. As mentioned above, the motor may still rotate slowly undesirably in the zero speed operating state. The reasons for this slow rotation include: the characteristics of the integral algorithm and the data processing of the encoder feedback channel.

[0100] Step 103: When it is determined that the motor is in a zero-speed running state, clear the output value of the integral circuit to zero.

[0101] As can be seen, the embodiments of the present invention determine whether the motor is in a zero-speed operating state based on the speed setpoint, the actual speed value, and the output value of the integral stage, thus achieving accurate determination of the zero-speed operating state. Moreover, the embodiments of the present invention focus on the root cause of the motor still rotating slowly in the zero-speed operating state. By clearing the output value of the integral stage to zero, for example, preferably by clearing it instantaneously, the unwanted motor rotation in the zero-speed operating state can be avoided.

[0102] In an exemplary embodiment, determining whether the motor is in a zero-speed operating state based on the speed setpoint, the actual speed value, and the output value of the integral element includes: determining that the motor is in a zero-speed operating state when the absolute value of the speed setpoint is less than a preset first threshold, the absolute value of the actual speed value is less than a preset second threshold, and the absolute value of the output value of the integral element is less than a preset third threshold; wherein the first threshold and the second threshold are respectively related to the speed reference value of the motor, the third threshold is related to the torque reference value of the motor, and the first quotient of the first threshold divided by the speed reference value of the motor and the second quotient of the second threshold divided by the speed reference value of the motor are respectively less than or equal to 0.01. When the motor is in a zero-speed operating state, the absolute value of the output value of the integral element is usually not zero. After the zeroing operation in step 103, the absolute value of the output value of the integral element can be cleared to zero.

[0103] In an exemplary embodiment, the first threshold value is the product of A% and the speed reference value, the second threshold value is the product of B% and the speed reference value, and the third threshold value is the product of C% and the torque reference value, where the value range of A is [0, 0.04], the value range of B is [0, 0.08], and the value range of C is [1, 8]. Preferably, both A% and B% are greater than the minimum motor speed that the encoder can recognize, expressed as a scalar. For example, the minimum motor speed that the encoder can recognize, expressed as a scalar, is the result of dividing the actual motor speed corresponding to the minimum pulse feedback rate by the rated speed of the motor. For example, assuming the motor uses an HTL encoder with 1024 pulses / revolution, when the minimum pulse rate is 1 pulse / s, the actual motor speed corresponding to this minimum pulse feedback rate is 1 / 1024*60 = 0.059 rpm. If the rated speed (usually a speed reference value) is 1500 rpm, then the minimum motor speed that the encoder can recognize is 0.059 / 1500*100% = 0.004%. Preferably, for the S120 frequency converter, the value of A is 0.02, the value of B is 0.04, and the value of C is 4.3.

[0104] The above illustrative descriptions illustrate typical examples of the first, second, and third threshold values. Those skilled in the art will recognize that these descriptions are merely illustrative and not intended to limit the scope of protection of the embodiments of the present invention. Therefore, the embodiments of the present invention propose preferred numerical ranges for each threshold value.

[0105] In an exemplary embodiment, clearing the output value of the integral circuit includes: when the duration of the motor being in a zero-speed running state is greater than or equal to a predetermined delay time, the output value of the integral circuit is cleared to zero, preferably instantaneously. It is evident that this embodiment of the invention avoids erroneous state determination by comparing the duration of the zero-speed running state.

[0106] In an exemplary embodiment, clearing the output value of the integral element includes: setting the inverter control word to enable a non-enabled speed controller command within a predetermined time period. Therefore, this embodiment of the invention achieves rapid control by setting the inverter control word.

[0107] In the exemplary embodiment, the predetermined time period is longer than one sampling period of the speed control process. Therefore, the predetermined time period in this embodiment of the invention is longer than the sampling period, ensuring that the process of eliminating the output value of the integral element is performed at least once during the control process, thus guaranteeing the reliability of the zeroing process.

[0108] In an exemplary embodiment, eliminating the integral output value within a predetermined time period includes: generating a positive pulse signal with a duration of the predetermined time period based on the speed setpoint, the actual speed value, and the integral output value; inverting the positive pulse signal into a negative pulse signal; and providing the negative pulse signal to the control bit in the inverter control word used to enable or disable the speed controller enable command. Therefore, this embodiment of the invention can conveniently eliminate the integral output value through pulse signal processing.

[0109] Figure 2 This is an exemplary logic diagram illustrating motor speed control using PI control according to an embodiment of the present invention. Figure 2 In this PI controller, the first signal arithmetic unit 201, the proportional arithmetic unit 202, the multiplier 203, the integrator 204, and the second signal arithmetic unit 205 together constitute the PI controller.

[0110] exist Figure 2 In this process, the motor speed setpoint V_1 and the actual motor speed V_2 are respectively input to the first signal arithmetic unit 201. The speed setpoint V_1 is then compared with the summation terminal of the first signal arithmetic unit 201. Figure 2 Connected using the addition symbol "+" in the first signal arithmetic unit 201, the actual speed value V_2 is connected to the subtraction terminal of the first signal arithmetic unit 201. Figure 2(Identified by the subtraction symbol "-" in the first signal arithmetic unit 201). The actual speed value V_2 is used for motor speed control to form a closed loop. The first signal arithmetic unit 201 compares the speed setpoint V_1 and the actual speed value V_2 to determine the speed deviation value V_deta between the speed setpoint V_1 and the actual speed value V_2, where V_deta = V_1 - V_2. Then, the speed deviation value V_deta is input to the proportional arithmetic unit 202 and the multiplier 203. In the proportional arithmetic unit 202, proportional adjustment is performed for the speed deviation value V_deta to obtain the proportional adjustment output value T_1. For example, assuming the proportional gain of the proportional arithmetic unit 202 is Kp, then T_1 = V_deta * Kp. In the multiplier 203, the speed deviation value V_deta is multiplied by the integral adjustment coefficient Ki. Then, the multiplier 203 inputs the product to the integral arithmetic unit 204. Integrator 204 performs integration on the product along the time dimension to obtain the integral adjustment output value T_2 of the speed deviation value V_deta. The proportional adjustment output value T_1 and the integral adjustment output value T_2 are respectively input to the second signal processor 205. The proportional adjustment output value T_1 is connected to one addition terminal of the second signal processor 205, and the integral adjustment output value T_2 is connected to the other addition terminal of the second signal processor 205. In the second signal processor 205, the superposition value T_sum of the proportional adjustment output value T_1 and the integral adjustment output value T_2 is calculated, where T_sum = T_1 + T_2. Figure 2 In this process, the same speed deviation value V_deta is output to the proportional and integral components respectively to participate in the specific calculations of the proportional and integral components. In reality, the speed deviation values ​​output to the proportional and integral components can not be the same, and there can be many other implementation methods. The embodiments of this invention are not limited in this regard.

[0111] exist Figure 2 In this process, the output value of the integral stage is T_2. That is, when transitioning from a non-zero speed operating state to a zero speed operating state, the output value T_2 of the integral stage needs to be eliminated.

[0112] Figure 3 This is an exemplary schematic diagram illustrating motor speed control according to an embodiment of the present invention. Figure 3In this example, the S120 frequency converter is used as an example. In the PI control 300: the speed setpoint is r1438, the actual speed is r1445; the speed deviation of the proportional element is r0064; the speed deviation of the integral element is r1454; the output value of the proportional element is r1481; and the output value of the integral element is r1482. r0063 is filtered by 301 to obtain r1445. The speed deviation of the integral element, r1454, is processed by multiplier 303 and integrator 304, and after upper and lower limit processing by 306, the output value of the integral element, r1482, is obtained. That is, when entering zero-speed operation, the output value r1482 of the integral element needs to be eliminated.

[0113] Figure 4 This is an exemplary schematic diagram illustrating how the present invention determines whether a motor is in a zero-speed operating state. Figure 4 The following example uses the S120 frequency converter. For instance, the following three conditions can be used to determine whether the motor is in a zero-speed running state. Condition (1): The absolute value of the speed setpoint r1438 is less than 0.02%; Condition (2): The absolute value of the actual speed value r1445 is less than 0.04%; Condition (3): The absolute value of the integral link output r1482 is less than 4.3%. When the frequency converter's operation command is enabled and these three conditions are met, it can be determined that the motor has reached a zero-speed running state, and at this time, the integral link output value can be cleared to zero. Preferably, when the motor transitions from a non-zero-speed running state to a zero-speed running state, the integral link output value is cleared to zero. For example, the frequency converter's operation command remains enabled (ON / OFF1 = 1), but the speed setpoint is set from a non-zero value to zero, thus the motor transitions from a non-zero-speed running state to a zero-speed running state. Here, based on the common expression in industrial settings, the specific values ​​of the speed setpoint and the actual speed value are percentage values ​​relative to the speed reference value. The specific value of the torque output in the integral stage is also a percentage value relative to the torque reference value.

[0114] like Figure 4As shown, the speed setpoint r1438, the actual speed value r1445, and the integral stage output r1482 are input to their respective absolute value units 401, 402, and 403 to perform absolute value processing. Then, the absolute values ​​of the speed setpoint r1438, the actual speed value r1445, and the integral stage output r1482 are input to their respective numerical comparator units 404, 405, and 406 to perform numerical comparison processing. Specifically: in numerical comparator unit 404, the absolute value of the speed setpoint r1438 is used as input and compared with 0.02% as the comparison object; in numerical comparator unit 405, the absolute value of the actual speed value r1445 is used as input and compared with 0.04% as the comparison object; and in numerical comparator unit 406, the absolute value of the integral stage output r1482 is used as input and compared with 4.3% as the comparison object. When the comparison result indicates that the input value is less than the compared value, the output terminal of the numerical comparator unit 405, 406, or 407 outputs a high level to the AND gate logic circuit 501. In the AND gate logic circuit 501, a logical AND operation is performed on the output of the numerical comparator unit 405, 406, or 407. When the AND gate logic circuit 501 outputs a high level, it can be determined that the motor is in a zero-speed running state.

[0115] The description of whether the motor is in a zero-speed operating state is given in specific numerical values. Those skilled in the art will recognize that such description is merely exemplary and is not intended to limit the scope of protection of the embodiments of the present invention.

[0116] The speed controller enable command for the S120 frequency converter is located at bit 12 of control word 1. When this command is set to 1, the speed controller outputs normally; when it is set to 0, the speed controller outputs zero. By using this command, when it is determined that the motor has reached zero speed, the command can be temporarily blocked, thereby eliminating the output of the integral part of the speed controller. Furthermore, since this command quickly returns to 1, it will not affect subsequent operations. The logic for implementing the above processing is as follows: Figure 5 As shown. Figure 5 This is an exemplary schematic diagram illustrating the execution speed control output according to an embodiment of the present invention. It includes: a power-on delay timer 502, a pulse generator 503, and a converter 504 (e.g., a NOT gate). Each time the motor reaches a zero-speed operating state, Figure 5 The logic shown will output a 2ms negative pulse. By connecting this negative pulse to bit 12 of control word 1, the integral output torque is eliminated without affecting subsequent operations. Specifically, in Figure 5In this process, the power-on delay timer 502 filters the result of the logical AND operation for a predetermined time (e.g., 500ms). The positive pulse generator 503 generates a positive pulse signal within a predetermined time period (e.g., 2ms, which needs to be greater than one sampling period of the speed control process, preferably less than two sampling periods) based on the filtered logical AND operation result. The converter 504 converts the positive pulse signal into a negative pulse signal, wherein the negative pulse signal is provided to the 12th bit of control word 1.

[0117] Figure 6 This is a schematic diagram of an exemplary waveform for the speed controller enable command according to an embodiment of the present invention.

[0118] Depend on Figure 6 As can be seen, when the motor state (S1) changes to a high level indicating zero-speed operation, the non-enabled speed controller enable command (S2) is initiated, which means the speed controller output is zero, thereby eliminating the output value of the integral element. After processing by the embodiment of the present invention, the take-up roller operates sensitively and is accurately positioned, meeting the operational requirements.

[0119] Figure 7 This is a schematic diagram illustrating an exemplary process for execution speed control according to an embodiment of the present invention. Figure 7 This example uses the S120 frequency converter. In the PI control of the S120 frequency converter: the speed setpoint is r1438, the actual speed is r1445, and the output value of the integral term is r1482. Here, it is assumed that the speed setpoint r1438, the actual speed is r1445, and the output value of the integral term r1482 are no longer percentage values ​​relative to the reference values, but rather the actual values.

[0120] The first absolute value unit 701 is configured to output the first absolute value of the first quotient of the given speed value divided by the motor speed reference value; the second absolute value unit 702 is configured to output the second absolute value of the second quotient of the actual speed value divided by the speed reference value; the third absolute value unit 703 is configured to output the third absolute value of the third quotient of the output value of the integral stage divided by the motor torque reference value; the first numerical comparator unit 704 is configured to output a first logic value where the first absolute value is less than a first threshold value, wherein the first logic value is logic 1 when the first absolute value is less than the first threshold value, and logic 0 otherwise; the second numerical comparator unit 705 is configured to output a second logic value where the second absolute value is less than a second threshold value, wherein the second logic value is logic 1 when the second absolute value is less than the second threshold value, and logic 0 otherwise; the third numerical comparator unit 706 is configured to output a third logic value where the third absolute value is less than a third threshold value, wherein the third logic value is logic 1 when the third absolute value is less than the third threshold value, and logic 0 otherwise. AND gate logic circuit 707 performs a logical AND operation on a first logic value, a second logic value, and a third logic value to produce a logical AND operation result; power-on delay timer 708 is used to filter the logical AND operation result within a delay time; positive pulse generator 709 is used to generate a positive pulse signal within a predetermined time period when the duration of the logical AND operation result is greater than the delay time; converter 710 is used to convert the positive pulse signal into a negative pulse signal, wherein the negative pulse signal is provided to the 12th bit of control word 1.

[0121] Figure 8 This is a structural diagram of the motor control device according to an embodiment of the present invention.

[0122] The motor control device 800 includes:

[0123] The determination module 801 is configured to determine the speed setpoint of the motor, the actual speed value, and the output value of the integral element of the frequency converter for the speed control process of the motor;

[0124] The judgment module 802 is configured to determine whether the motor is in a zero-speed running state based on the speed setpoint, the actual speed value, and the output value of the integral element.

[0125] Elimination module 803 is configured to clear the output value of the integral circuit when it is determined that the motor is in a zero-speed running state.

[0126] In an exemplary embodiment, the determination module 802 is configured to determine that the motor is in a zero-speed operating state when the absolute value of the speed setpoint is less than a preset first threshold, the absolute value of the actual speed is less than a preset second threshold, and the absolute value of the output value of the integral element is less than a preset third threshold; wherein the first threshold and the second threshold are respectively related to the speed reference value of the motor, the third threshold is related to the torque reference value of the motor, and the first quotient of the first threshold divided by the speed reference value of the motor and the second quotient of the second threshold divided by the speed reference value of the motor are respectively less than or equal to 0.01.

[0127] In an exemplary embodiment, the first threshold value is the product of A% and the speed reference value, the second threshold value is the product of B% and the speed reference value, and the third threshold value is the product of C% and the torque reference value, wherein the value range of A is [0, 0.04]; the value range of B is [0, 0.08]; and the value range of C is [1, 8].

[0128] In an exemplary embodiment, the elimination module 803 is configured to clear the output value of the integral circuit when the duration of the motor being in a zero-speed running state is greater than or equal to a predetermined delay time.

[0129] In an exemplary implementation, the elimination module 803 is configured to disable the speed controller enable command for a predetermined time period by setting the inverter control word.

[0130] In an exemplary embodiment, the predetermined time period is longer than one sampling period of the speed control process. In an exemplary embodiment, the elimination module 803 is configured to generate a positive pulse signal with a duration of the predetermined time period based on the speed setpoint, the actual speed value, and the output value of the integral element; to invert the positive pulse signal into a negative pulse signal; and to provide the negative pulse signal to the control bit in the inverter control word for enabling or disabling the speed controller enable command.

[0131] In an exemplary embodiment, the elimination module 803 includes: a first absolute value taking unit configured to output the first absolute value of a first quotient of a given speed value divided by a speed reference value of the motor; a second absolute value taking unit configured to output the second absolute value of a second quotient of an actual speed value divided by a speed reference value; a third absolute value taking unit configured to output the third absolute value of a third quotient of a third quotient of an integral element output value divided by a torque reference value of the motor; a first numerical comparator unit configured to output a first logic value where the first absolute value is less than a first threshold value; and a second numerical comparator unit configured to output a second absolute value where the second absolute value is less than a second threshold value. The system includes: a second logic value of the threshold; a second numerical comparator unit configured to output a third logic value whose absolute value is less than the third threshold; an AND gate logic circuit that performs a logical AND operation on the first, second, and third logic values ​​to produce a logical AND operation result; a power-on delay timer for filtering the logical AND operation result within a delay time; a positive pulse generator for generating a positive pulse signal for a predetermined time period based on the filtered logical AND operation result; and a converter for converting the positive pulse signal into the negative pulse signal, wherein the negative pulse signal is provided to the control bit.

[0132] Figure 9 This is another exemplary structural diagram of the motor control device according to an embodiment of the present invention. For example... Figure 9 As shown, the motor control device 900 includes a memory 901 and a processor 902. The processor 902 is used to call the computer program stored in the memory 901 to execute the motor control method in this embodiment of the invention.

[0133] This invention also proposes a computer program product. The computer program product is tangibly stored on a computer-readable storage medium and includes computer-readable instructions, which, when executed, cause at least one processor to perform the motor control method described above. Specifically, a system or apparatus equipped with a storage medium storing computer-readable code that implements the functions of any of the embodiments described above can be provided, and the computer (or CPU or MPU) of the system or apparatus can read and execute the computer-readable code stored in the storage medium. Furthermore, the operating system or the like operating on the computer can perform some or all of the actual operations through instructions based on the computer-readable code. The computer-readable code read from the storage medium can also be written to a memory provided in an expansion board inserted into the computer or to a memory provided in an expansion unit connected to the computer. Subsequently, the instructions based on the computer-readable code cause a CPU or the like installed on the expansion board or expansion unit to perform some or all of the actual operations, thereby implementing the functions of any of the embodiments described above. In this embodiment, embodiments of computer-readable media include, but are not limited to, floppy disks, CD-ROMs, magnetic disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), memory chips, ROMs, RAMs, ASICs, configured processors, all-optical media, all magnetic tapes or other magnetic media, or any other media from which a computer processor can read instructions. Furthermore, various other forms of computer-readable media can send or carry instructions to a computer, including routers, private or public networks, or other wired and wireless transmission devices or channels, such as downloading computer-readable instructions from a server computer or the cloud via a communication network. Instructions may include code in any computer programming language, including C, C++, C++, Visual Basic, Java, and JavaScript.

[0134] It should be noted that not all steps and modules in the above processes and system structure diagrams are mandatory; some steps or modules can be omitted as needed. The execution order of each step is not fixed and can be adjusted as required. The system structure described in the above embodiments can be a physical structure or a logical structure. That is, some modules may be implemented by the same physical entity, or some modules may be implemented by multiple physical entities, or they may be jointly implemented by certain components in multiple independent devices.

[0135] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A motor control method (100), characterized in that, include: Determine the setpoint speed of the motor, the actual speed, and the output value of the integral element of the inverter for the speed control process of the motor (101). Based on the given speed value, the actual speed value, and the output value of the integral element, determine whether the motor is in a zero-speed running state (102). When it is determined that the motor is in a zero-speed operating state, the output value of the integral element is cleared to zero (103); wherein, The step of determining whether the motor is in a zero-speed operating state based on the given speed value, the actual speed value, and the output value of the integral element (102) includes: When the absolute value of the speed setpoint is less than a preset first threshold, the absolute value of the actual speed is less than a preset second threshold, and the absolute value of the output value of the integral element is less than a preset third threshold, the motor is determined to be in a zero-speed operating state; wherein the first threshold and the second threshold are respectively related to the speed reference value of the motor, the third threshold is related to the torque reference value of the motor, and the first quotient of the first threshold divided by the speed reference value of the motor and the second quotient of the second threshold divided by the speed reference value of the motor are respectively less than or equal to 0.

01.

2. The motor control method (100) according to claim 1, characterized in that, The first threshold value is the product of A% and the speed reference value, the second threshold value is the product of B% and the speed reference value, and the third threshold value is the product of C% and the torque reference value, wherein the value range of A is [0, 0.04]; the value range of B is [0, 0.08]; and the value range of C is [1, 8].

3. The motor control method (100) according to claim 1 or 2, characterized in that, The step of clearing the output value of the integral stage (103) includes: When the duration of the motor running at zero speed is greater than or equal to a predetermined delay time, the output value of the integral element is cleared to zero.

4. The motor control method according to claim 1 or 2, characterized in that, The step of clearing the output value of the integral stage (103) includes: By setting the inverter control word, an enable command for the non-enabled speed controller is given within a predetermined time period.

5. The motor control method (100) according to claim 4, characterized in that, The predetermined time period is longer than one sampling period of the speed control process.

6. The motor control method (100) according to claim 4, characterized in that, The step of clearing the output value of the integral stage (103) includes: Based on the speed setpoint, the actual speed value, and the output value of the integral element, a positive pulse signal with a duration of the predetermined time period is generated; The positive pulse signal is inverted into a negative pulse signal; The negative pulse signal is provided to the control bit in the inverter control word for enabling or disabling the speed controller enable command.

7. A motor control device (800), characterized in that, include: The determining module (801) is configured to determine the speed setpoint of the motor, the actual speed value, and the integral output value of the inverter for the speed control process of the motor; The judgment module (802) is configured to determine whether the motor is in a zero-speed running state based on the given speed value, the actual speed value and the output value of the integral link; The elimination module (803) is configured to clear the output value of the integral element to zero when it is determined that the motor is in a zero-speed operating state; wherein, The judgment module (802) is configured to determine that the motor is in a zero-speed running state when the absolute value of the speed setpoint is less than a preset first threshold value, the absolute value of the actual speed value is less than a preset second threshold value, and the absolute value of the output value of the integral element is less than a preset third threshold value; wherein the first threshold value and the second threshold value are respectively related to the speed reference value of the motor, the third threshold value is related to the torque reference value of the motor, and the first quotient of the first threshold value divided by the speed reference value of the motor and the second quotient of the second threshold value divided by the speed reference value of the motor are respectively less than or equal to 0.

01.

8. The motor control device (800) according to claim 7, characterized in that, The first threshold value is the product of A% and the speed reference value, the second threshold value is the product of B% and the speed reference value, and the third threshold value is the product of C% and the torque reference value, wherein the value range of A is [0, 0.04]; the value range of B is [0, 0.08]; and the value range of C is [1, 8].

9. The motor control device (800) according to claim 7 or 8, characterized in that, The elimination module (803) is configured to clear the output value of the integral link to zero when the duration of the motor being in a zero-speed running state is greater than or equal to a predetermined delay time.

10. The motor control device (800) according to claim 7 or 8, characterized in that, The elimination module (803) is configured to disable the speed controller enable command within a predetermined time period by setting the inverter control word.

11. The motor control device (800) according to claim 10, characterized in that, The predetermined time period is longer than one sampling period of the speed control process.

12. The motor control device (800) according to claim 11, characterized in that, The elimination module (803) is configured to generate a positive pulse signal with a duration of the predetermined time period based on the speed setpoint, the actual speed value, and the output value of the integral element; to invert the positive pulse signal into a negative pulse signal; and to provide the negative pulse signal to the control bit in the inverter control word for enabling or disabling the speed controller enable command.

13. The motor control device (800) according to claim 12, characterized in that, The elimination module (803) includes: The first absolute value unit is configured to output the first absolute value of the first quotient of the speed setpoint divided by the speed reference value of the motor. The second absolute value unit is configured to output the second absolute value of the second quotient of the actual speed value divided by the speed reference value; The third absolute value unit is configured to output the third absolute value of the third quotient of the output value of the integral element divided by the torque reference value of the motor; The first numerical comparator unit is configured to output a first logic value whose absolute value is less than a first threshold value; The second numerical comparator unit is configured to output a second logic value whose second absolute value is less than a second threshold value; The second numerical comparator unit is configured to output a third logic value whose absolute value is less than a third threshold value; AND gate logic circuits perform a logical AND operation on a first logic value, a second logic value, and a third logic value to produce a logical AND operation result; A power-on delay timer is used to filter the result of the logical AND operation within a delay time. A positive pulse generator is used to generate a positive pulse signal for a predetermined time period based on the filtered result of the logical AND operation. A converter for converting the positive pulse signal into the negative pulse signal, wherein the negative pulse signal is provided to the control bit.

14. A motor control device (900), characterized in that, include: The memory (901) is configured to store computer-readable code; The processor (902) is configured to invoke the computer-readable code to execute the motor control method (100) as described in any one of claims 1 to 6.

15. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-readable instructions, which, when executed by a processor, cause the processor to perform the motor control method (100) as described in any one of claims 1 to 6.

16. A computer program product, characterized in that, The computer program product is tangibly stored on a computer-readable storage medium and includes computer-readable instructions that, when executed, cause the processor to perform the motor control method (100) as described in any one of claims 1 to 6.

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