DC Soft Start

[c11]

Hello,

I am looking to implement a "soft start" solution on a DC starting motor and I am running out of ideas. The motor itself is capable of drawing a maximum 2000A @ 70VDC (very short period of time mind you), and therefore I am limited to the components that I can use. I originally thought an IGBT with PWM might work but cannot find much information on controlling the power in a smooth manner (to essentially limit the in rush current).

Any ideas?

Thanks!

 

[Skogsgurra]

Starting resistors were and are used. Anything against them?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

If you limit the current very much the starter won't turn the engine. The characteristics of a series wound DC starting motor are very much different that the characteristics of the three phase induction motors where soft starts are most often employed.
In addition, a soft start applied to a load such as a starting motor sees may fail. Soft starts are not noted for high starting torque when applied to induction motors.

Bill
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"Why not the best?"
Jimmy Carter

 

[iop995]

By added resistors (various diameter cables connection) seem to be simplest solution. With 0.035ohm motor resitance, can control start-up current by cables connections. If motor is serie excitation will be naturaly adapted to start-up with very high loads. For paralel excitation must do same tests and choose added resistors accordingly (limit maxim current at minim possible and have minim start-up torque to move load).

 

[ScottyUK]

What type of motor? A motor with a shunt field is well suited to using resistors in the armature to limit the current while maintaining the field at full strength. A series motor is much less amenable to use of series resistors because the field is weakened.