Motor Controllers - FAQs

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Can I use an industrial motor with the Curtis AC controller?
No, the industrial motors are wound for high voltage operation. The AC induction motor controllers designed for material handling applications are wound for low voltage, typically in the 15 – 50 V rms range. We work closely with motor suppliers and can help you to locate a suitable motor.
Do I need an inverter and a controller?
No, the Curtis AC controller converts the DC battery power into low voltage 3 phase AC power while simultaneously controlling motor torque speed and direction. As an added bonus you also dispense with costly direction contactors and additional power wiring.
What type of encoder do I need?
You need a 2 channel quadrature encoder which provides motor speed and direction feedback for the controller. This ensures the best efficiency from the control system which in turn gives cooler running and longer battery life. Many of the AC induction motors now incorporate and integral bearing encoder.
Is the AC system very powerful when starting?
Yes, the Curtis vector controlled algorithms provide high torque start up conditions with both 4 and 6 pole 3 phase induction motors. In many applications the performance exceeds conventional DC systems.
What is VCL used for?
VCL is the unique Curtis Vehicle Control language. The 1234, 1236, 1238 controllers and the 1310 Vehicle System Controller have a PLC type facility that allows you, the customer, to download your own specific code into the controller. By using this you can rid yourself of the relay interface logic of times past. You can also drive your entire truck through the VCL and CANbus system.
What is the maximum speed for the motor?
The Curtis AC controllers can output a sine wave from 0 – 300Hz and drive 2, 4 or 6 pole motors. This equates to a theoretical maximum speed of 12000 rpm for 2 poles, 6000 rpm for 4 poles and 3000 rpm for 6 poles.
What are the benefits of using AC?
With the Curtis AC + VCL controllers you have an ageless system because as your market requirements change then so can your VCL. Never again do you have to throw out the entire control system just to add a new feature. On the motor side, the AC solution can provide sealed motors with no brushes to maintain. AC also provides closed loop control which means no over-speeding and burst armatures. Adding to this fewer contactors means that both reliability and performance is increased for your product.