IGBT H-Bridge power drives 1

[simkay]

hi ,
i m trying to design an IGBT H-Bridge power drive for a dc motor. it concerns the position control of a conveyor belt driven by a conventional dc motor. the function of the controller is to control the position of the belt within a specified displacement. any websites, books or advice on that subject will be very helpful. thanks.

 

[ScottyUK]

Have a look on IR's website for integrated bridge driver circuits. These do most of the awkward stuff like controlling deadtime between switching, level shifting, etc, etc.



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If we learn from our mistakes,
I'm getting a great education!

 

[blacksea]

If you need IGBT for power bridge really? What's motor power?

 

[mc5w]

Emerson makes some H-bridge drives named mini-maestro, midi-maestro, and maxi-maestro. These are for use with servo motors that are specifically designed to tolerate the carrier frequency and so forth.

I would NOT recommend using an ordinary DC motor for this application unless you are usijng a motor-generator drive. The rotor of a standard DC motor is far too coarse. GEC Alstom Parvex makes servo motors that use a printed circuit rotor to achieve 193 commutator bars in an 8-pole stator.

Your zero speed torque will be 80% of full speed torque because unwanted current from the carrier will be at maximum at zero speed - similar to a AC motor that is 80% power factor but with harmonic currents instead of reactive current.

Also DO NOT forget to install a melting alloy or bimetallic overload relay so as not to rely on what is alledgedly built into the drive. That also applies to packedaged AC drives - install a bimetallic after the manufacturer's back is turned.

You should also consider getting rid of your DC motor and go with an off the shelf AC servo drive. However, you should derate ANY manufacturer's claim as to how much torque, speed, and acceleration that it can take. When you hit the maximum of any parameter the gain of the system drops to zero not to mention that running the motor at maximum torque produces maximum heat.

Mike Cole mc5w AT earthlink dot net

 

[baltic]

1. When selecting IGBT, take about 50% voltage margin - e.g., for 400V maximum DC bus voltage use 600V rated IGBT (this is because of voltage spike at turn-off due to parasitic layout inductance).

2. Take about 50% current margin with respect to amplifier continous current (this assumes typical 2X peak current that may be tolerated for 1s).

3. Use unipolar PWM technique to avoid maximum PWM current ripple at zero speed, increased motor and filter capacitor losses.

4. Select (connected in parallel) filter (bypass) capacitors to avoid overheating due to ESR (equivalent serial resistance) losses.

5. If DC bus has no regen capability, you will have to add braking regulator that dissipates motor energy into power resistor during braking (generator mode).