Ratio of load inertia to servo motor inertia: (J_load /J_motor)
J_load: Load inertia J_motor: Motor rotor inertia
When selecting the servo drives and motors that the user want to use, the user not only should consider the motor torque and rated speed, but also need to know the ratio of load inertia to servo motor inertia.
Then, the user can select the proper motor that is correctly matched for the servo drive according to the actual requirements of the connected machine (load condition) operation and the quality and quantity requirements for materials processing and manufacturing.
When perform tuning and trial run, setting (J_load /J_motor) correctly is the most important / essential for optimizing the performance of the mechanical system and servo system and make them work efficiently.
2012年5月14日 星期一
慣性比的意義是什麼?
伺服馬達的負載慣量比：(J_load /J_motor)
J_load為負載慣量
J_motor為馬達轉子慣量
在伺服系統選型時，除考慮馬達的扭矩和額定速度等等因素外，我們還需要先計算得知機械系統換算到馬達軸的慣量，再根據機械的實際動作要求及加工件質量要求來具體選擇具有合適慣量大小的馬達；在調試時,正確設定慣量比參數是充分發揮機械及伺服系統最佳效能的前題。
J_load為負載慣量
J_motor為馬達轉子慣量
在伺服系統選型時，除考慮馬達的扭矩和額定速度等等因素外，我們還需要先計算得知機械系統換算到馬達軸的慣量，再根據機械的實際動作要求及加工件質量要求來具體選擇具有合適慣量大小的馬達；在調試時,正確設定慣量比參數是充分發揮機械及伺服系統最佳效能的前題。
2012年5月10日 星期四
High-inertia motor is not always better and the low-inertia motor is not always worse. It depends on application.
1. High-inertia motor is not always better and the low-inertia motor is not always worse. It depends on application.
T= I x α (Torque = Inertia x Angular Acceleration)
P= T x ω (Power Rating = Torque x Angular Acceleration)
P = I x α x ω
Therefore, with the same power, if the inertia is increased, the acceleration must be decreased which means the characteristics of the acceleration and deceleration are worse. Of course, the angular speed will be changed, too. Here, we assume that the operating speed remains the same.
“I “ is a fixed value. After a system (such as flying shear system, the flying shear will not change. But if it is used for conveyer belt, the inertia will change. When the goods on the belt become more, the drag force should be strengthened.) is set, the users can use the formula (T=I*α) to estimate the acceleration and deceleration, and the required torque.
α = (target speed- initial speed)/ (needed time from initial speed to target speed)
If a system needs the torque of 1 N-m, and using either high-inertia or low-inertia motor is able to achieve the performance, the low-inertia motor is a better choice if a quick response and a high speed are desired.
Therefore, it can be easy to explain why low-inertia motor is better by the above formula. Because the rotor inertia of the low-inertia motor is lower and the rotor is lighter also, so when the motor stops, the regenerative power will be less. By the same logic, hitting the wall at the same speed, the power of the fat person is bigger than the thin person’s.
In conclusion, if the application requires quick response and good acceleration and deceleration characteristics, the low-inertia motor is more applicable (if the torque force is enough). If the application needs large torque, such as heavy lifting system, the high-inertia motor would be more suitable.
T= I x α (Torque = Inertia x Angular Acceleration)
P= T x ω (Power Rating = Torque x Angular Acceleration)
P = I x α x ω
Therefore, with the same power, if the inertia is increased, the acceleration must be decreased which means the characteristics of the acceleration and deceleration are worse. Of course, the angular speed will be changed, too. Here, we assume that the operating speed remains the same.
“I “ is a fixed value. After a system (such as flying shear system, the flying shear will not change. But if it is used for conveyer belt, the inertia will change. When the goods on the belt become more, the drag force should be strengthened.) is set, the users can use the formula (T=I*α) to estimate the acceleration and deceleration, and the required torque.
α = (target speed- initial speed)/ (needed time from initial speed to target speed)
If a system needs the torque of 1 N-m, and using either high-inertia or low-inertia motor is able to achieve the performance, the low-inertia motor is a better choice if a quick response and a high speed are desired.
Therefore, it can be easy to explain why low-inertia motor is better by the above formula. Because the rotor inertia of the low-inertia motor is lower and the rotor is lighter also, so when the motor stops, the regenerative power will be less. By the same logic, hitting the wall at the same speed, the power of the fat person is bigger than the thin person’s.
In conclusion, if the application requires quick response and good acceleration and deceleration characteristics, the low-inertia motor is more applicable (if the torque force is enough). If the application needs large torque, such as heavy lifting system, the high-inertia motor would be more suitable.
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意見 (Atom)