I have a 100 HP (75 kW) 1500 RPM motor in a sugar mill, operating a TurboRotor. The motor is oversized due to the large torque it needs to apply to start the turbo rotor, there is no solution to this problem because the motor was sold integrated in the machinery.

However, the motor can be equipped with an inverter because the load of sugar is intermittent. When the silo needs sugar a valve opens and feeds the turbo rotor, during which the electric motor consumes 40,5 kW, when the silo is full the valve closes and the motor keeps operating in "No Load" consuming 33,8 kW. It isn't profitable to turn off the motor because it takes too long to start and it would result in damage to it.

Therefore I decided to use an inverter to control the speed for the "Load- no Load" problem. Can you help me with the detailed energy savings part, because I am used to calculating for Pumps but this is a different situation.

At one of my work site there is a inverter which is running a motor coupled to conveyor belt
Power dips of duration 1s is somewhat frequent at site
due to this power fluctuation the frequency inverter earlier tripped, after enabling the auto restart and flying restart option in the parameter, now the inverter is not tripping but during the power dip the motor slows down and once the dip gone ramps up back. since the motor is loaded the dc link capacitor is discharging quickly
I want to avoid this speed variation occurring
so one solution which I sort out is to add additional dc link capacitor to existing so as to hold as much energy to withstand the power dip occurring
I don't know how practical it would be. And if this possible what all are the design/selection criteria, also I would like to know other alternative solution.
The inverter is Micromaster mm430 [siemens make]

This paper makes a comparison between the inverter and hydraulic coupling by introducing the methods and principles of inverter, analyses the situation of fans and pumps in term of energy saving. We think the inverter control program is matured, its energy saving is obviously. Inverter will be widely used in various power plants.

Variable frequency control inverter is a new electric drive and it has rapid development in twentieth century, mainly used in AC motor speed control. Its technology and performance are better than any other kind of speed control mode (such as: Voltage Step-down speed control, pole changing speed control, slip speed control, internal feedback cascade speed control and hydraulic coupling). The inverter speed control has a great acceptance in broad users as its remarkable energy saving, high-precision speed control, wide adjustment range，faultless power electronics protection, as well as easy implementation of the automatic communication function. Inverter also brings great convenience to user in safe operation, reliable installation, maintenance etc, which makes domestic and foreign enterprises adopt best choice of energy-saving method for motor.

Principle
As we know, the relationships of speed (N), flow(Q), pressure(H) and power(P) is as follows：

Q1/ Q2＝n1/n2
H1/ H2＝(n1/n2)2
P1/ P2＝(n1/n2)3

From above, if other operating conditions remain unchanged, through reducing motor speed, energy-saving effect is very remarkable. For example, working condition only demands 50% flow, personnel can adjust speed to half of rated. Power consumption is only 12.5% of rated value, that is, theoretically, energy saving rate can reach to 87.5%.

I have an application that require running an 55Kw high efficiency induction motor at rated torque at any rpm from 5% to 100% of the rated rpm. It will be controlled by a frequency inverter with FOC.

This motor has independent cooling fan running with a separate motor that is capable of removing 5Kw heat from the motor. It will be controlled by an inverter with FOC. The motor is a good 95% efficient with cast copper rotor / not the regular cast aluminum. Can an induction motor give out full torque at 5% of its rated rpm with an inverter?? My concern is it may over heat at low frequency - not due to cooling fan because that is independent, but due to the other reasons.