Important factors for servo control system replacement
In many cases, we need to use a servo product replacement solution, such as replacing a existing motor with a new servo motor. Reasons may include: product scrap, cost savings, delivery time, or technical upgrade. A large number of important factors may need to be considered when it comes to the specific context of each application.
1. Healthy motivation
Regardless of the reason you need to replace a servo product, you must understand and always keep in mind the top priority: reduce risk. A good replacement program can minimize the possibility of encountering during the upgrade process
potential problem. If the potential risks in the replacement process are not carefully managed, the probability of system failure increases. Therefore, cost should not be the decisive factor in the replacement program!A good replacement solution not only minimizes risk, but also reduces system costs, rather than lowering costs but accepting higher potential risks.
2. shaft stability
Inertia matching is very important, but it is often overlooked. The servo used for replacement should have the same rotor inertia as the original servo, or be as similar as possible. The goal is to keep the system after installing the new servo
stability. Of course, the assumption here is that the original system has reached the required stability. If you want to replace a lower resolution system (such as a tachometer, reversing encoder, or old fashioned resolver type system), usually a high resolution sinusoidal encoder feedback device with a resolution of not less than 220 lines per revolution (CPR). Flexibility can be added with matching rotor inertia.In general, when using a high-resolution device to improve the resolution of the feedback device, the inertia of the replacement servo must be at least one-third of the original motor. Of course, it is better to achieve half.This method has been successfully used in many application areas.
3. speed and torque
Speed and torque matching are equally important. The performance of the replacement motor should meet or exceed the performance of the original motor. Analyze both catalog parameter values (ie continuous torque, rated speed) to ensure that there is no defects are very important.
The torque value must also be compared over the speed range of each motor. Comparing graphics is a very helpful practice by comparing motor speed/torque curves and manually in spreadsheets draws the desired value. For example, plot the continuous torque at 1000 PRM,Motor A = X Nm and motor B = Y Nm, and the same operation is performed over the entire speed range.
4. motor size
Although the size is not particularly important for the performance of the motor, during the replacement process, if the new servo motor is installed in the same size as the original motor, it will help to achieve the flow. Should be analyzed outline drawings of the two motors to ensure consistency. Even replacing a motor that uses an industry standard base (such as NEMA or ICE) is a good way. The relevant standards generally stipulate the same guide the size of the adapter and bolt ring, but the shaft size is often not fixed. For example, although you are replacing a NEMA 34 motor, the product definitions of each manufacturer may vary greatly!
Is the motor the only part that has been replaced in the machine? In general, replacing the servo means replacing the drive, cable, and in some cases even replacing the controller. under these circumstances,motor winding differences can be a secondary consideration if following the manufacturer's recommendations.
However, if the replaced motor will be used with the original drive, it should be carefully checked. For example, for winding data (including motor constants: Kt and Ke), feedback device type and resolution and cable pin layouts, etc. must be carefully checked and matched. In addition, different servo motor manufacturers typically use different units and conversion methods for these key parameters. This may be difficult to clearly distinguish the definition and unit of the motor during the comparison process. This article provides some useful supplementary information in this regard, and introduces some common considerations in the servo replacement process.