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Can a motor Driver to be used as generator controller too?

Massimiliano Curzi
Prodigy 30 points

Hi,

I am designing a vertical axis wind turbine electrical drivetrain, using a PMSM (permanent magnet synchronous machine) and since it is not self starting, I was planning to control the machine as a motor, once I decided to start it, then when it reach the desired speed I would like to release the control as motor and start controlling the speed and torque while absorbing power and charge a battery.

The configuration will be the following

PMSM <-> Driver <-> Battery

                          ^

                          |

              anemometer 

.

Desired behavior

Stage one: PMSM not running

Stage two: wind blows, anemometer detect good wind, and send signal to the driver, to start spinning the machine

Stage three: once the machine spins at the desired speed, the driver goes into a "speed control mode", so that for each wind speed we have a specific rotational speed to maintain, and draw energy from the wind to charge the battery

The question is if the TI motor driver  can also be used as generator controller.

Thanks for the attention,

Max

  • 0
    TI__Guru** 114905 points

    Hi Massimiliano,

    This is an interesting question. The devices are designed to drive motors, not absorb power to charge a battery.

    Let me check around and get back to you. It may take a few days.

    What type of motor are you planning to use?

  • 0
    TI__Expert 8885 points

    Max,

     Any 3-phase H-bridge is inherently capable to handle bi-directional power conversion i.e. it can be used in motoring mode and in generating mode wherein motor mechanical energy is converted to electric to charge the DC-side battery. Therefore by default, all the TI’s 3-phase driver can be used in both of above modes as long as voltage, current and power ratings involved during the conversion remains within MOSFET and Diodes ratings.

    The only thing to observe is that none of TI’s 3 phase H bridge drivers are  not equipped with dynamic barking resistor across DC-BUS so you can observe high voltage across DC-bus during generating mode. You should take-care proper precaution at system level to prevent DC bus over-voltage to avoid any failure related to this.

    Best Regards

    Milan

  • 0 in reply to Rick Duncan
    Prodigy 30 points

    Rick Duncan said:

    Hi Massimiliano,

    This is an interesting question. The devices are designed to drive motors, not absorb power to charge a battery.

    Let me check around and get back to you. It may take a few days.

    What type of motor are you planning to use?

    Hi Duncan,

    Thanks for the quick reply

    the machine is yet to be chosen, but as general specification it will be a Permanent Magnet Synchronous Machine with a rated power around 100W and with a speed of about 400rpm @50W. 

    best,

    Max

  • 0 in reply to Milan Rajne
    Prodigy 30 points

    Milan Rajne said:

    The only thing to observe is that none of TI’s 3 phase H bridge drivers are  not equipped with dynamic barking resistor across DC-BUS so you can observe high voltage across DC-bus during generating mode. You should take-care proper precaution at system level to prevent DC bus over-voltage to avoid any failure related to this.

    Hi Milan,

    Thanks for the quick reply, I'll discuss the possibility with my colleagues. If any other suggestion do not come up in some time, I will consider the question "motor controller as generator controller" solved, remaining to find the right precautions to prevent DC-bus overvoltage.

    Best,

    Max

  • 0 in reply to Massimiliano Curzi
    TI__Guru** 119380 points

    As Milan said.

    Our InstaSPIN-FOC solution is all ready to go with what is called "four quandrant operation".

    IF the flux of your machine is such that the Bemf voltages will be higher than your bus is capable of taking you should

    1. change your motor

    2. or add a break resistor to sink current

    2. or add control logic to handle this scenario. there are diffferent methods depending on system needs.