I have started testing a new motor. However, the RPM does not rise again.

[JasonLEE]

Hi, @RupakC 

I have started testing a new motor.
However, the RPM does not rise again.

Although the rated current was raised and the gatekill allowable range was widened, the RPM did not rise and the IPM exploded.

A new parameter value is needed again this time.

If you look at the specifications below, these are the test measurements for the new motor.

27.45mH

2.3ohm

36.0=KE

I attached the parameter file that I set.
I think we need a new value from Q60 to 63.
Please check and reply.

[RupakC]

Hello @JasonLEE 

I have a few points that you may want to consider/reply to:

1. Are you using the same older power board as mentioned in https://community.infineon.com/t5/Motor-Control-ICs/High-RPM-rise-and-Hall-sensor-problems/td-p/3905... ?

2. I understand that now you are using a new motor which is bigger. Hence, the motor current rating should be higher. Can you clarify what is the rated current for the motor? I see that the entered value is still 10A in Q2. Please elaborate. 

3. The flux estimator time constant is supposed to be 4 to 5 times L/R. Based on your entered values, the L/R ratio is 0.0119. Thus, a range of 48-60msec may be selected for Q60.

4. For Q61, Q62 and Q63, you need to test the motor and based on your observations of the motor performance, you need to tune these parameters. 

5. In addition to the MCE Wizard related settings, I remember last time the smaller motor was drawing enough current such that there was a need to improve the thermal design of the power board. In case of a bigger motor drawing more current, this issue may lead to board failure and thus, needs to be adequately addressed. 

Best Regards

[JasonLEE]

Hi, @RupakC 

Thank you for your reply

1. Yes, the power board is using the same power board as before. 
The type of motor is the same.
But the size of the motor is bigger.
The shaft and stator and rotor sizes of the motor have been improved and the load is greater.

2. I understand that the maximum "GK" value that IPM can withstand is 30A. Therefore, the rated current appears to be the maximum that 10A can set.
If too high a rated current is used, a higher "GK" value is required. This will cause overcurrent and damage to the hardware.
Therefore, I set the maximum allowable rated current to 10A.

3. In this case, could you provide the exact value as before?

4. I will measure the waveform the same as before and attach it as an video. Can you calculate the exact value?

5. In this case, I installed a large heat sink to release heat.

* In the case of 3~4, it is the most difficult for me to calculate this part. I would like you to provide the exact calculation value as you provided before. (In this case, it means Q60~63) *

[RupakC]

Hello @JasonLEE 

There are some issues that need to be addressed here. We should first know the exact cause for the IPMs exploding. Below I have shared my thoughts:

1. In your last thread, you had mentioned you are having two boards- EVAL M1 818A and EVAL M1 828A. Can you please confirm which board you are using here? Please note that the Eval M1 818A has a maximum current rating of 6A for ac current. Rated current for IPM IM818-Mcc is 10A. Also, please see the below waveform for the IM818-MCC waveforms of case temperature vs Output current. Please note that if output current values rise to around 6.2A, the case temperature rises to 100 degrees Celsius (depending on the chosen switching frequency). If you cannot increase the motor current limit beyond 10A, then it depends on the load whether the motor will be able to drive the load at 2000rpm or not. Using EVAL M1 818, motor current cannot exceed 6-7A and the IPM will explode.  

   

2. If you are using the EVAL M1828A, then the IPM used is IM828-Xcc and the case temperature to Output current waveform is as under:

    

   Here also, depending on what is the switching frequency you use, you may see that the output current is limited at higher case temperatures.  Even for this case, whether the motor can run the load at rated speed or not depends on the load, since you have limited the motor input current at 10A.

3. How have you implemented the heat sink? Please go through the document https://www.infineon.com/dgdl/Infineon-AN2019-16_CIPOS_MAXI_IM818_series-ApplicationNotes-v01_21-EN.... to design your heat sink. You may also consider using a fan for cooling.
4. For calculating the values for Q61, Q62 and Q63, please send me the motor current and voltages  along with the motor reference speed and actual speed waveforms such that I can try to suggest some values.

Best Regards

[JasonLEE]

Hello, @RupakC 

Thanks as always for your kind replies.
I'm learning so much from you.
You are a very good teacher.

1. This project uses a custom board designed by myself.
This design is identical to the EVAL board.
My custom board uses two IPMs.
IM818LCC and IM828XCC.
The current increased size motor uses the IM828XCC.

2. I raised the motor's rated current until the PCB blew up, but the RPM doesn't go up.
I don't know the cause.
I think the switching frequency should be changed.

3. The heat sink is very well designed. I will attach a photo. Please check the photo.

4. I will make an image of the requested part of the waveform and attach it as before.

5. This new motor should also be able to reach 2000 RPM. Please provide a solution as before.

6. I have an additional question.
I believe the new motor requires a motor rated current of 15A to 20A.
However, this requires a higher "GK" tolerance, and setting it too high can cause hardware failure.
What is the maximum allowable range for "GK"? I think I'll need about 40 to 50A.
What should I do in this case?

My motor can withstand up to 20A.
But I don't know if the hardware can stand it.
How many maximum current can the board of the EVAL-IM828XCC withstand?

7. I tried to measure a waveform, but an error persisted and the waveform could not be measured. Is it because the rated current of the motor is high? Or is it because the IC chip or IPM is broken? Please reply. thank you.

Please check the attached video.

 

  

 

[RupakC]

Hello @JasonLEE 

I have the following points on the issues mentioned in your last post. 

1. Please check page 20 of the following link:
   https://www.infineon.com/dgdl/Infineon-IM828-XCC-DataSheet-v02_01-EN.pdf?fileId=5546d4627448fb2b0174...
   The IM828-XCC has a current limit of 14A but the temperature variations change with change of switching frequency. 
2. Can you let me know what was the value of motor current when the PCB blew up? From the second video in the attachment, I can see that the motor current rises to more than 10A and then it stops. This is normal. The motor load is too high and more than 10A current will be needed to drive it at higher speeds. The Motor current set in the MCE Wizard is 10A and the iMotion will not allow higher currents.
3. Okay. I assume the heat sink compound/paste was properly used and there is proper heat dissipation through the heat sink.
4. Okay.
5. Whether the motor can drive the load at 2000RPM with 10A current input will depend on the load. If the load is higher, the current limit needs to be increased but the IPM may fail in that case. Hence a newer board may need to be designed with an IPM that can withstand more current.
6. Did the “GK fault” trigger while using the bigger motor? Please try to increase this limit  if you start getting the gate kill fault.
7. The IPM used in the hardware cannot withstand 20A current. Hence a newer design is needed. The EVAL-M1-828-A has a recommended current limit of 15/19A and it is not recommended to use it for applications requiring more than the rated current. I believe you have used the EVAL-M1-828-A board as reference while creating your custom board.
8. We would recommend you reduce the sampling rate in the MCE designer. Alternatively, you can probe the actual hardware and record the voltage and current waveforms in DSO.

Best Regards

[JasonLEE]

Hi @RupakC 

1. The IPM no longer had an explosion due to overheating. After sufficient installation of the heat sink and heat paste, the symptoms of overheating disappeared.

2. The maximum current was 20A when the PCB burst.
Is the maximum motor rated current for this IPM is 15A?
I'm currently testing it with 13A.

3. Motor rated current was set to 13A and the motor was tested. Maximum RPM reached 1300 to 1350.
However, the windings of the motor overheated and the motor became extremely overheated.

4. I would like to design an IPM that can withstand more current as you suggested.
However, I understand that IM828XCC is the best specification. No higher specifications were found. Could you recommend a higher specification IPM and reference design?

5. The "GK" tolerance has been raised to a maximum of 50A.

6. Could you tell me how to reduce the sampling rate in MCE designer?
How much is the right value?

* Here's my conclusion. *

- The product of another company has the same motor as my company's product. They rise to 1750 RPM.
The motor is similar in load, winding and size to ours.
I don't know why.

- I wonder if changing the IPM and increasing the rated current can solve this problem.

- I wonder if it is best to reduce the load or if we can solve this problem by changing the IPM.

Best Regards

Jason L

[RupakC · Accepted solution]

Hello @Jason 

Please go through the datasheet for the IPM at the following link
https://www.infineon.com/dgdl/Infineon-IM828-XCC-DataSheet-v02_01-EN.pdf?fileId=5546d4627448fb2b0174...

The current rating depends on your switching frequency and the maximum allowable case temperature that the board designer has set. 

2. It is mentioned that the motor rated current is 15-20A . Please let me know the exact value mentioned in the motor datasheet. Also, if the motor rated current is 15A, its windings will surely overheat if 20A is allowed to flow into the motor.

It is mentioned that you are testing the motor with 13A. What is the value of motor rated current that you have entered in MCE Wizard during this testing?

3. If the motor speed rose to 1350RPM while taking 13A as input current, then it means the load is too much for the motor and it will need more current to drive the load at higher speeds. Now, since the motor windings overheat, it seems that the motor current limit is already reached. Now, you have two options:

A. Reduce the load.
B. Select a bigger motor with higher rated current while keeping the load same. 

For the second option, you need to re-design the board with an alternate IPM that can handle more current. 

Please check the following link to calculate the power dissipation for the IPM: 
https://plex.infineon.com/plexim/ipmmotor.html?_ga=2.43014572.801051108.1676264713-2108589164.166599...

What is the dc bus voltage in your board? 

4. We currently do not have any SiC IPM with higher current capacity than the IM818-XCC. However, Infineon has a wide range of semiconductor and SiC products that may be used. You may use our discrete MOSFETs with higher current ratings. Please visit our product selection webpage for more information: 

https://www.infineon.com/cms/en/product/promopages/pm-selection-guide/

5. The GK tolerance is for overcurrent protection. There is no need to set it to such high values.

6. The sampling rate can be changes from the window as shown below:

We cannot comment on the other product as we do not know if it uses Infineon controller. 

Best Regards