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MCF8315C-Q1: Can't Reach Maximum Speed

Shehab Abdelmagid
Prodigy 100 points
Part Number: MCF8315C-Q1
Other Parts Discussed in Thread: MCF8315D, MCF8315C

Tool/software:

Hello,

I have Interior PMSM motor which i can't reach its maximum speed (720Hz) unless i increase the Supply voltage from 13.5V to 15V when controlling it with MCF3815C-Q1.

With the normal voltage (13.5) i have CURRENT_SATURATION_LOOP Fault, and when i looked it says due to lower VVM.

I enabled overmodulation and made the Kp and Ki params 0 but this could not help. 

Please note that i can control the speed fine as long as it is not the maximum speed lets say until 89% of max speed.

However i have  another controller and could drive to the motor to the maximum speed just fine at the same voltage.

So my questions are:

1-On what bases Vvvm is said to be lower?

2-Can the HW FOC control this type of motor efficiently [Interior PMSM] and if yes what i should do to achieve my speed and torque needs?

Thank You.

Shehab Abdelmagid,

  • 0
    TI__Mastermind 22972 points

    Hi Shehab,

    Can you verify R, L of the motor and what is used with the EEPROM configuration.

    You can first test in current loop by disabling speed loop, test if speed can be achieved, but I feel modulation is already maximum.

    Do you have current consumption information with other device when it is able to drive to max speed?

    That can be flux weakened mode.

    You can evaluate MCF8315D which has Lead/lag angle configuration and also if we need enable flux weakening.

    Thanks and Best Regards

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 100 points

    Hi ,

    R and L are consistent.

    i had already tried to switch to the current loop but i did not achieve the maximum speed.

    Which current you refer to the Bus Current or which one exactly?

    Do i need to have the Flux Weakening Or Lead/Lag angle configuration to reach the maximum speed @No Load for IPMSM? otherwise i will not be able to achieve them using the MCF8315C? 

    Thanks for your response and best regards.

    Shehab Abdelmagid

  • 0 in reply to Shehab Abdelmagid
    TI__Mastermind 22972 points

    Hi Shehab, 

    I am referring to the phase current, you have already tried it.

    Under no load we dont need to try flux weakening but it will provide ide if speed is increasing. 

    You can try lead angle, can you confirm what is the speed difference observed?

    Without lead angle what is the speed difference and with lean angle is there any improvement.

    Thanks and Best Regards

    Venkatadri S