1、Servomotors / Servo Drivers Servo Motor Selection Flow Chart Explanation References Determine the size, mass, coefficient of friction, and external forces of all the moving part of the Servo Motor the rotation of which affects. - Determine the operating pattern (relationship between time and speed)
2、of each part that must be controlled. Convert the operating pattern of each controlled element into the motor shaft operating pattern. Operation Pattern Formula The elements of the machine can be separated so that inertia can be calculated for each part that moves as the Servo Motor rotates. Calcula
3、te the inertia applied to each element to calculate the total load inertia of the motor shaft conversion value. Inertia Formulas Calculation of Friction Torque Calculates the frictional force for each element, where necessary, and converts it to friction torque for a motor shaft. Calculation of Exte
4、rnal Torque Calculates the external force for each element, where necessary, and converts it to external torque of a motor shaft. Calculates the total load torque for the motor shaft conversion value. Load Torque Formulas Select a motor temporarily based upon the motor shaft converted load inertia,
5、friction torque, external torque and r.p.m of a motor. - Calculate the Acceleration/Deceleration Torque from the Load Inertia or Operating Pattern. Acceleration/Deceleration Torque Formulas Calculate the necessary torque for each part of the Operating Pattern from the Friction Torque, External Torqu
6、e and Acceleration/Deceleration Torque. Confirm that the maximum value for the Torque for each operating part (Maximum Momentary Torque) is less than the Maximum Momentary Torque of the motor. Calculate the Effective Torque from the Torque for each Operating part, and confirm that it is less than th
7、e Rated Torque for the motor. Calculation of Maximum Momentary Torque, Effective Torque Calculate Regenerative Energy from the Torque of all the moving parts. Please see the user manual of each productfor the details on calculation of the regenerative energy. Check if the the number of encoder pulse
8、s meets Accuracy of Positioning the system specified resolution. Check if the calculation meets the specifications of the temporarily selected motor. If not, change the temporarily selected motor and re-calculate it. The following table Specialized Check Items Check Items Load Inertia Load Inertia M
9、otor Rotor Inertia x Applicable Inertia Ratio Effective Torque Effective Torque Motor Rated Torque Please allow a margin of about 20%. * Maximum Momentary Torque Maximum Momentary Torque Motor Maximum Momentary Torque Please allow a margin of about 20%. * For the motor Maximum Momentary Torque, use
10、the value that is combined with a driver and the one of the motor itself. Maximum Rotation Speed Maximum Rotation Speed Rated Rotation Speed of a motor Try to get as close to the motors rated rotations as possible. It will increase the operating efficiency of a motor. For the formula, please see “St
11、raight-line Speed and Motor Rotation Speed“. Regenerative Energy Regenerative Energy Regenerative Energy Absorption of a motor When the Regenerative Energy is large, connect a Regenerative Energy Absorption Resistance to increase the Absorption capacity of the driver. Encoder Resolution Ensure that
12、the Encoder Resolution meets the system specifications. Characteristics of a Positioner Check if the Pulse Frequency does not exceed the Maximum Response Frequency or Maximum Command Frequency of a Positioner. Operating Conditions Ensure that values of the ambient operating temperature/humidity, ope
13、rating atmosphere, shock and vibrations meet the product specifications. *When handling vertical loads and a load affected by the external torque, allow for about 30% of capacity. Effective Torque: A value of the average torque (RMS) that is produced during operation of a motor. A motor with a large
14、r value than the effective torque must be chosen. The unit is (N m). Regenerative Energy: The power produced by a motor when it operates as a generator. The regenerative energy is produced by the external forces, such as gravity, during Servomotor deceleration. Measures must be included in the desig
15、n to keep the regenerative energy within the energy absorption capacity. The unit is (J). Formulas for Operating Patterns Inertia Formulas Load Torque Formulas Acceleration/Deceleration Torque Formula Calculation of Maximum Momentary Torque, Effective Torque Positioning Accuracy Straight Line Speed
16、and Motor Rotation Speed Sample Calculations (1) Machinery Selection (2) Determining Operating Pattern (3) Calculation of Motor Shaft Conversion Load Inertia (4) Load Torque Calculation (5) Calculation of Rotation Speed (6) Motor Temporary Selection *Note that this value changes according to the Series. (7) Calculation of Acceleration/Deceleration Torque (8) Calculation of Maximum Momentary Torque, Effective Torque (9) Result of Examination Note:This example omits calculations for the regenerative energy, operating conditions, or positioner characteristics.
