A dynamic slip vector control method for eccentric large inertia load of an asynchronous motor

Abstract

The application discloses a dynamic slip vector control method for eccentric large-inertia load of an asynchronous motor, and comprises the following steps: an operation vector equation of the asynchronous motor is as follows: a voltage steady-state equation: S1, Usd=Rs*isd-omega1*(Ls*Lr-Lm2) / Lr*isq; S2, Usq=Rs*isq+omega1*(Ls*Lr-Lm2) / Lr*isd+omega1*Lm / Lr*psi r, wherein, Usd and Usq are d-axis and q-axis voltages of a stator, isd and isq are d-axis and q-axis target currents of the stator, Rs and Ls are a stator resistance and inductance, omega1 is a synchronous frequency of the stator, psi r is a total rotor flux, Lr is a rotor inductance, and Lm is mutual inductance; and the application patent of the variable-slip vector control method for the eccentric large-inertia load of the asynchronous motor can effectively solve the problem of the coordination relationship among the gravity eccentric load acceleration / deceleration starting, constant-speed energy saving and constant-speed speed stability through the dynamic slip compensation control.

Description

Technical Field

[0001] This invention relates to the field of control technology for controlling asynchronous motors to drive gravity-driven eccentric loads, and in particular to a dynamic slip vector control method for asynchronous motors driving eccentric loads with large inertia. Background Technology

[0002] In the field of motor drive control, many loads driven by asynchronous motors are eccentric loads whose center of gravity is not located at the center of the circle. When controlling such loads with motor drives, acceleration and deceleration during start-up, constant speed energy saving, and constant speed control stability have long been major challenges in application.

[0003] Depend on Figure 1 and Figure 2 It can be seen that they all run in a clockwise direction. When the load reaches... Figure 1 At this point, the point of gravity is on the right. The weight of the load will cause the disk to fall rapidly and automatically. If the motor driver does not intervene, the disk's speed will increase rapidly, meaning gravitational energy (potential energy) is converted into kinetic energy. When the load reaches... Figure 2 When the point of gravity is on the left, the weight of the load will cause the disk to automatically and rapidly fall counterclockwise. At this point, the motor driver needs to drive the motor to overcome gravity and the load, putting it in electric mode so that the disk can accelerate clockwise. Therefore, when the motor controller controls the asynchronous motor under eccentric load, in... Figure 1 In this stage, to control the speed of the disc and prevent it from falling too quickly, the motor driver needs to convert gravitational energy (potential energy) into electrical energy. The motor is in a generating state, storing the generated energy in the bus capacitor of the motor driver. At this time, the DC voltage of the bus capacitor will increase. When the DC bus voltage rises to the energy consumption braking point, it will trigger the energy consumption resistor to conduct. The gravitational energy (potential energy) will be converted into heat energy through the heating of the resistor. If this continues for a long time, the temperature of the energy consumption resistor will be very high, and a lot of energy will be consumed. To address this, we propose a dynamic slip vector control method for asynchronous motors with eccentric large inertia loads. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a dynamic slip vector control method for asynchronous motors with eccentric large inertia loads. This invention patent for a variable slip vector control method for asynchronous motors with eccentric large inertia loads can effectively solve the coordination problem of acceleration and deceleration start-up, constant speed energy saving, and constant speed stability of gravity eccentric loads through dynamic slip compensation control.

[0005] To solve the above technical problems, the present invention provides the following technical solution: a dynamic slip vector control method for an asynchronous motor with an eccentric large inertia load, comprising: when the motor driver controls the load in the asynchronous motor, the motor operation is divided into acceleration and deceleration state, electric constant speed state and generator constant speed state;

[0006] The following are methods for coordinating unbalanced gravitational eccentric loads during motor operation:

[0007] The vector equations for the operation of the asynchronous motor are as follows:

[0008] Voltage steady-state equation:

[0009] S1, Usd=Rs·isd-ω1·(Ls·Lr-Lm2) / Lr·isq

[0010] S2, Usq=Rs·isq+ω1·(Ls·Lr-Lm2) / Lr·isd+ω1·Lm / Lr·ψr

[0011] Where: Usd and Usq are the stator d-axis and q-axis voltages, isd and isq are the stator d-axis and q-axis target currents, Rs and Ls are the stator resistance and inductance, ω1 is the stator synchronous frequency, ψr is the rotor total flux linkage, Lr is the rotor inductance, and Lm is the mutual inductance.

[0012] Based on the operating state of the asynchronous motor, the following equation can be obtained:

[0013] S3, ωs=Lm·isq / Tr / ψr

[0014] Where: ωs is the theoretical slip frequency, Tr=Lr / Rr is the rotor electromagnetic time constant, and Rr is the rotor resistance;

[0015] Because there is a certain error between the obtained rotor resistance value and the actual resistance value of the motor, a slip compensation gain coefficient K is added to the slip frequency that actually takes effect in order to eliminate this error. The actual slip frequencies used are as follows:

[0016] S4, ωsj=ωs·K

[0017] Where K is 1.00 at the factory, and its value ranges from 0.00 to 3.00. When it is 1.00, no correction is made.

[0018] The actual stator synchronization frequency of the asynchronous motor controlled by the motor driver is as follows:

[0019] S5, ω1=ωsj+ωm

[0020] Where: ωm is the actual identified or measured rotor frequency of the motor, that is, controlling ωsj can control the speed difference between the stator frequency and the rotor frequency, and the synchronous frequency ω1 is generated by the motor driver to control the slip frequency ωsj.

[0021] Torque equation of asynchronous motor:

[0022] S6, T = np·Lm·isq·ψr / Lr

[0023] Based on equations S4 and S6 and the rotor electromagnetic time constant Tr, the torque equation of the asynchronous machine can be derived:

[0024] S7, T=(np·ψr2 / Rr)·ωsj

[0025] Where: np is the number of pole pairs of the motor.

[0026] As a preferred technical solution of the present invention, it can be seen from the S7 equation that, within the stable region of the motor's inherent speed-torque characteristic curve, the actual output torque value of the asynchronous motor can be controlled by controlling the magnitude of the slip frequency ωsj. The value of ωs is determined by ωsj = ωs·K, based on the current torque current setting and motor parameters. When the value of K changes, the value of K is controlled to control the magnitude of the actual output torque T of the asynchronous motor. When ωsj is 0, the motor driver controls the asynchronous motor not to output torque. Within the stable region of the motor's inherent speed-torque characteristic curve, the larger ωsj is, the larger the torque output by the asynchronous motor.

[0027] Compared with the prior art, the beneficial effects that this invention can achieve are:

[0028] For eccentric gravity loads where the center of gravity is not located at the center of the circle, we utilize different control values ​​of K under various conditions to achieve a coordinated relationship between the start-up, energy saving, and speed stability of the unbalanced eccentric gravity load. Figure 1 During this phase, to prevent the disk from falling too quickly, the motor driver needs to convert gravitational energy (potential energy) into electrical energy. The motor is in a generator state, storing the generated electricity in the bus capacitor of the motor driver. At this time, the DC voltage of the bus capacitor increases. In generator state, this provides a change in the DC bus voltage. This invention correlates the change in DC bus voltage with the K value, using the change in DC bus voltage to control the P regulator, thereby controlling the change in the K value. This achieves a balance between energy saving and speed stability during steady-speed motor operation. When the slip frequency is not adjusted, i.e., K is at the factory default value (typically 1.00), the speed is stable, but the power generation is high, energy consumption is high, and energy saving is not achieved. When the slip frequency control is completely zero, the speed fluctuation is large and the system speed vibration is large. This invention correlates the change in DC bus voltage with the K value, uses the change in DC bus voltage value to control the P regulator, and then controls the change in K value, so that the motor can achieve energy saving when running at a steady speed. However, when the DC bus voltage rises to a certain value, the speed can be quickly stabilized, that is, coordinated control is achieved between energy saving and speed stability. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a gravity-driven eccentric load of the present invention.

[0030] Figure 2 This is a schematic diagram of the active state of a gravity eccentric load driven by a motor according to the present invention.

[0031] Figure 3 This is the overall block diagram of the dynamic slip frequency ωsj control added to this invention. Detailed Implementation

[0032] To make the technical means, creative features, and achieved objectives and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0033] Example:

[0034] like Figure 1-3 As shown, a dynamic slip vector control method for an asynchronous motor with an eccentric, large inertia load includes:

[0035] When the motor driver controls the load in an asynchronous motor, the motor operation is divided into acceleration and deceleration state, constant speed motoring state, and constant speed generatoring state.

[0036] The following are methods for coordinating unbalanced gravitational eccentric loads during motor operation:

[0037] The vector equations for the operation of the asynchronous motor are as follows:

[0038] Voltage steady-state equation:

[0039] S1, Usd=Rs·isd-ω1·(Ls·Lr-Lm2) / Lr·isq

[0040] S2, Usq=Rs·isq+ω1·(Ls·Lr-Lm2) / Lr·isd+ω1·Lm / Lr·ψr

[0041] Where: Usd and Usq are the stator d-axis and q-axis voltages, isd and isq are the stator d-axis and q-axis target currents, Rs and Ls are the stator resistance and inductance, ω1 is the stator synchronous frequency, ψr is the rotor total flux linkage, Lr is the rotor inductance, and Lm is the mutual inductance.

[0042] Based on the operating state of the asynchronous motor, the following equation can be obtained:

[0043] S3, ωs=Lm·isq / Tr / ψr

[0044] Where: ωs is the theoretical slip frequency, Tr=Lr / Rr is the rotor electromagnetic time constant, and Rr is the rotor resistance;

[0045] Because there is a certain error between the obtained rotor resistance value and the actual resistance value of the motor, a slip compensation gain coefficient K is added to the slip frequency that actually takes effect in order to eliminate this error. The actual slip frequencies used are as follows:

[0046] S4, ωsj=ωs·K

[0047] Where K is 1.00 at the factory, and its value ranges from 0.00 to 3.00. When it is 1.00, no correction is made.

[0048] The actual stator synchronization frequency of the asynchronous motor controlled by the motor driver is as follows:

[0049] S5, ω1=ωsj+ωm

[0050] Where: ωm is the actual identified or measured rotor frequency of the motor, that is, controlling ωsj can control the speed difference between the stator frequency and the rotor frequency, and the synchronous frequency ω1 is generated by the motor driver to control the slip frequency ωsj.

[0051] Torque equation of asynchronous motor:

[0052] S6, T = np·Lm·isq·ψr / Lr

[0053] Based on equations S4 and S6 and the rotor electromagnetic time constant Tr, the torque equation of the asynchronous machine can be derived:

[0054] S7, T=(np·ψr2 / Rr)·ωsj

[0055] Where: np is the number of pole pairs of the motor.

[0056] According to the S7 equation, within the stable region of the motor's inherent speed-torque characteristic curve, the actual output torque of the asynchronous motor can be controlled by adjusting the slip frequency ωsj. The value of ωs is determined by ωs = ωs·K, based on the current torque current setting and motor parameters. When the value of K changes, the actual output torque T of the asynchronous motor is controlled. When ωsj is 0, the motor driver controls the asynchronous motor to not output torque. Within the stable region of the motor's inherent speed-torque characteristic curve, the larger ωsj is, the greater the output torque of the asynchronous motor.

[0057] For eccentric gravity loads where the center of gravity is not located at the center of the circle, we utilize different control values ​​of K under various conditions to achieve a coordinated relationship between the start-up, energy saving, and speed stability of the unbalanced eccentric gravity load. Figure 1 During this phase, to prevent the disk from falling too quickly, the motor driver needs to convert gravitational energy (potential energy) into electrical energy. The motor is in a generator state, storing the generated electricity in the bus capacitor of the motor driver. At this time, the DC voltage of the bus capacitor increases. In generator state, this provides a change in the DC bus voltage. This invention correlates the change in DC bus voltage with the K value, using the change in DC bus voltage to control the P regulator, thereby controlling the change in the K value. This achieves a balance between energy saving and speed stability during steady-speed motor operation. When the slip frequency is not adjusted, i.e., K is at the factory default value (typically 1.00), the speed is stable, but the power generation is high, energy consumption is high, and energy saving is not achieved. When the slip frequency control is completely zero, the speed fluctuation is large and the system speed vibration is large. This invention correlates the change in DC bus voltage with the K value, uses the change in DC bus voltage value to control the P regulator, and then controls the change in K value, so that the motor can achieve energy saving when running at a steady speed. However, when the DC bus voltage rises to a certain value, the speed can be quickly stabilized, that is, coordinated control is achieved between energy saving and speed stability.

[0058] Based on the state of the asynchronous motor, the motor operation can be divided into acceleration / deceleration state, constant speed motoring state, and constant speed generatoring state.

[0059] In the asynchronous motor's acceleration / deceleration and constant speed states, the K value remains unchanged and is the factory default value, typically 1.00, meaning the K value is not adjusted.

[0060] Under constant power generation speed, the change in DC voltage at the bus is controlled in a closed-loop manner by a P regulator, and the output is the K value. The specific steps are as follows:

[0061] Set a target value UdcRef1 for the DC bus voltage of the adjustment K value. This target value UdcRef1 is generally 10V lower than the energy consumption braking action point UdcRef2, but 50V higher than the normal standby DC bus voltage UdcRat, i.e., UdcRef1 = UdcRat + 50.

[0062] K = k p (U dc -UdcRef1), k p The P regulator adjusts the proportional gain;

[0063] The K value ranges from 0 to the factory default value, with the factory default value typically being 1.00. When the current DC bus voltage is less than UdcRef1, the K value is the factory default value. When the current DC bus voltage is equal to UdcRef1, the current K value is 0. When the current DC bus voltage is greater than or equal to UdcRef2, the current K value is the factory default value. At this time, the energy consumption braking action is activated, using the energy consumption resistor to heat up and consume energy on the bus to maintain a stable bus voltage.

[0064] Natural slip frequency ωs=Lm·isq / Tr / ψr

[0065] Actual slip frequency ωsj=ωs·K

[0066] The synchronous frequency of an actual asynchronous motor is ω1 = ωsj + ωm, where ωm is the rotor frequency of the motor that is actually identified or measured.

[0067] The motor driver outputs the control voltage for the asynchronous motor through voltage steady-state equations S1 and S2;

[0068] The motor driver outputs a synchronous frequency, controls the actual slip frequency, and then controls the actual output torque of the motor through the asynchronous motor torque equation 7, which in turn controls the speed of the asynchronous motor.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. A dynamic slip vector control method for an asynchronous motor with an eccentric, large inertia load, characterized in that, include: When the motor driver controls the load in an asynchronous motor, the motor operation is divided into acceleration and deceleration state, constant speed motoring state, and constant speed generatoring state. The following are methods for coordinating unbalanced gravitational eccentric loads during motor operation: The vector equations for the operation of the asynchronous motor are as follows: Voltage steady-state equation: S1, Usd=Rs·isd-ω1·(Ls·Lr-Lm2) / Lr·isq S2, Usq=Rs·isq+ω1·(Ls·Lr-Lm2) / Lr·isd+ω1·Lm / Lr·ψr Where: Usd and Usq are the stator d-axis and q-axis voltages, isd and isq are the stator d-axis and q-axis target currents, Rs and Ls are the stator resistance and inductance, ω1 is the stator synchronous frequency, ψr is the rotor total flux linkage, Lr is the rotor inductance, and Lm is the mutual inductance. Based on the operating state of the asynchronous motor, the following equation can be obtained: S3, ωs=Lm·isq / Tr / ψr Where: ωs is the theoretical slip frequency, Tr=Lr / Rr is the rotor electromagnetic time constant, and Rr is the rotor resistance; Because there is a certain error between the obtained rotor resistance value and the actual resistance value of the motor, a slip compensation gain coefficient K is added to the slip frequency that actually takes effect in order to eliminate this error. The actual slip frequencies used are as follows: S4, ωsj=ωs·K Where K is 1.00 at the factory, and its value ranges from 0.00 to 3.

00. When it is 1.00, no correction is made. The actual stator synchronization frequency of the asynchronous motor controlled by the motor driver is as follows: S5, ω1=ωsj+ωm Where: ωm is the actual identified or measured rotor frequency of the motor, that is, controlling ωsj can control the speed difference between the stator frequency and the rotor frequency, and the synchronous frequency ω1 is generated by the motor driver to control the slip frequency ωsj. Torque equation of asynchronous motor: S6, T = np·Lm·isq·ψr / Lr Based on equations S4 and S6 and the rotor electromagnetic time constant Tr, the torque equation of the asynchronous machine can be derived: S7, T=(np·ψr2 / Rr)·ωsj Where: np is the number of pole pairs of the motor.

2. The dynamic slip vector control method for an asynchronous motor with an eccentric large inertia load according to claim 1, characterized in that: According to the S7 equation, within the stable region of the motor's inherent speed-torque characteristic curve, the actual output torque of the asynchronous motor can be controlled by adjusting the slip frequency ωsj. The value of ωs is determined by ωs = ωs·K, based on the current torque current setting and motor parameters. When the value of K changes, the actual output torque T of the asynchronous motor is controlled. When ωsj is 0, the motor driver controls the asynchronous motor to not output torque. Within the stable region of the motor's inherent speed-torque characteristic curve, the larger ωsj is, the greater the output torque of the asynchronous motor.

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