When you are driving it, it has a lot of energy. Take an electric motor connected to a big fly-wheel. But if an external force speeds up the rotor faster than the electrical frequency, then the motor will naturally transition into regen as it converts mechanical energy into electrical energy. If the rotor is spinning slower than the electrical frequency, then the motor is operating in the usual fashion, as a motor. There is a lot of other stuff that could be written about this topic, but these are the basics. Because of the way they are designed, VFD's usually cannot put energy back into the grid. The VFD may even have an over-voltage failure when this happens, unless it has some way to dump the extra energy (for example into a load resistor). This will cause mechanical energy in the turntable to be converted into electrical energy. Because the electrical frequency is lower than the actual rotor frequency, the motor will be in regen. If the motor is turning a giant heavy turntable, for example, and the VFD needs to slow it down quickly, then the VFD will apply a frequency lower than the actual rotation of the motor. The VFD can control the frequency of the voltage applied to the motor, which means it can control the motor speed. Now lets consider a motor running from a variable frequency drive (VFD). You will be supplying power to the electrical grid instead of using the power from the grid. Now you have an induction generator rather than an induction motor. You could do this, for example, by connecting another motor (maybe a gas motor) to your electric motor, then over-drive the electric motor with the gas motor. In our example, this means you need to make the rotor spin faster than 3600 RPM. The way you put an induction motor into regeneration is to simply increase the mechanical speed of rotation higher than synchronous speed. So, basically, as you apply a load to an induction motor, it slows down a bit, and the torque increases, until the motor and load balance each other out (or maybe if the load is too much, the motor will stall). The larger the slip, the more torque the motor will produce, to a point. This speed difference, called "slip" gives rise to a current in the rotor which then generates torque. In this case, 3600 RPM would be called the "synchronous speed." Meaning that if the rotor actually was spinning at 3600 RPM, then the rotor and rotating field are in-sync.īut in normal motoring operation, the rotor spins a bit slower than 3600 RPM. If you consider a two-pole motor running on a 60 Hz system, the rotating field moves at 60 Hz * 60 sec/min = 3600 RPM. ![]() In an induction motor, the supplied voltage creates a rotating magnetic field around the rotor. ![]() If I decelerate a motor does that mean I have to mechanically stall its shaft and it will cause regeneration? What can be an example to deceleration in this context? How does such braking happen so that it causes regeneration? But the info says this regeneration will take place if a high inertia load is decelerated. I can understand first examples where a crane or an elevator is lowering a load it acts as a generator. In the rotating mass flows back through the motor to the drive. If a high inertia load is decelerated in this case, the energy stored Regeneration, as it is called, will also take place Occur if the load is giving up energy, such as when a crane orĮlevator is lowering a load, or maybe when a conveyor is transporting Is, from the load, through the motor, back to the drive. However, occasionally the energy flow will be in reverse, that Most of the time, in most applications, a variable frequency driveĬontrols the motor by supplying it with energy which then powers the Here is an info about regeneration due to braking:
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