Hello everyone, I'm a newcomer to this forum seeking guidance on troubleshooting my PowerFlex755 EENET frequency inverter. My goal is to perform a point-to-point positioning task, but I'm encountering a problem where the inverter consistently runs at 5Hz when I issue the start command, regardless of the reference input. Even when setting the reference speed to 10.0Hz, the output frequency exceeds 12.X (refer to the images attached). I suspect a minimum frequency setting might be causing this issue, but I haven't been able to locate the parameter responsible. Furthermore, could someone share their experience with positioning tasks utilizing a PowerFlex755 and Point-to-Point positioning? I believe addressing the aforementioned issue is essential for success in this task. Any programming examples or resources on Point-to-Point positioning would be greatly appreciated. Thank you in advance for your assistance!
When it comes to precise positioning, consider programming it as an axis with an encoder in the system. By utilizing motor parameters, the drive will adjust the output frequency to reach 10hz, providing accurate feedback and control.
I believe programming an axis may not be necessary if using PtP positioning. I have a SSI Encoder installed in the system, which provides accurate readings that change when a magnet is moved along the encoder bar. However, I am puzzled why the motor continues to run at 5Hz even after stopping the drive.
It appears that the drive is maintaining the motor at zero speed instead of stopping it. Instructing the drive to "stop" the motor does not necessarily mean it stops controlling the motor. With an encoder, the VFD relies on the encoder input to indicate zero speed. The output observed is the minimal amount of torque needed to keep the motor at zero speed. Based on the tag names used, it seems you may be involved in a lifting application where the drive's torque output is necessary to counteract gravity's pull on the load.
In a discussion, Lynx777 pointed out that it seems like the drive is keeping the motor at a standstill. Issuing a "stop" command to the drive may not necessarily stop it from controlling the motor. With an encoder in place, the VFD relies on the encoder input to confirm zero speed. The observed torque is likely needed to maintain the motor at this standstill. Additionally, based on the tag names used, it seems there may be a lifting application involved, where the drive's torque output supports the load against gravity. In my situation, I am testing with a small 0.3kW motor and do not have a load present. Could this behavior be due to my PtP mode parameters? I attempted a PtP task and noticed the motor running even without a reference command. It appears the issue lies in the PAR784 PTP command, which remains constant and matches the actual position of the SSI encoder.
Although I haven't personally utilized PTP mode with a PF755, I have experience using them in servo mode, also known as positioning mode or axis mode, and have observed similar behavior even with no load. Based on this, I believe that operating in PTP mode would yield comparable results. In my opinion, what you are witnessing is typical behavior of the drive as it maintains control of the motor to keep it in a specific position.
Hello and welcome to the forum! I've had a similar issue with the PowerFlex755 EENET in the past. It sounds like you're battling with an auto-tuning issue that's skewing your speed reference. I'd suggest trying to go through an auto-tuning process first, to help establish accurate motor parameters (it's done via configuration drive in the studio 5000). If that doesn't work, double-check the parameters settings A541 (Min Frequency), A542 (Max Frequency), and A560 (Start Boost). These sometimes cause the inverter to run at abnormal frequencies. Regarding Point-to-Point positioning, the PF755 handles it quite well with an encoder; I'd recommend looking at Rockwell's literature (Publication 750-PM001C-EN-P) for specific programming examples. It provides an excellent deep-dive into the topic!
Hey there, welcome to the forum! In dealing with your PowerFlex 755 issue, it's possible that your minimum frequency parameter (P108) is set above your desired speed causing it to run at a faster rate. However, there could be other contributing factors too, like if your acceleration/deceleration rates (P111 & P112) are set too high. As for Point-to-Point positioning, the PowerFlex 755 manual has a detailed section on that subject. In terms of practical application, I’ve found that ensuring the precise tuning of your motor control can greatly impact the success of these tasks. Experimenting with different PID settings can assist you in achieving optimum performance. Good luck and don't hesitate to post any more queries as you get into it!
Welcome to the forum! It sounds like you're dealing with a challenging issue. The issue you're describing could potentially be an issue with your scaling parameters; these can interfere with the final output frequency. If you're using analog inputs, Parameter 29 (Speed Reference 1 Select) should be checked and Parameter 664 (Input Reference Scale Max) may also be relevant. For positioning tasks, I've found Rockwell's PowerFlex 750-Series Programming Manual incredibly useful, particularly the section related to Point-to-Point Positioning (P3). It provides some in-depth examples you might find helpful. For troubleshooting, Parameter 01 [Output Frequency] could help diagnose what's happening in real-time. If you suspect a minimum frequency setting, Parameter 45 [Min Output Freq] and Parameter 47 [Start At Freq] might be useful to check. This is just a starting point, and it might not completely fix the problem, but hopefully this information will help you get closer to a solution!
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Answer: The issue might be related to a minimum frequency setting in the parameters. Check the inverter's settings to adjust the minimum frequency parameter.
Answer: To address this issue, review the inverter's settings and ensure that the parameters are correctly configured to match the desired reference speed.
Answer: Other users may share their experiences with positioning tasks utilizing PowerFlex755 and provide insights or tips on how to troubleshoot common issues like the one mentioned.
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