“Moving Ahead” 2009

“Moving Ahead” 2009 Today’s Application Requirements  Precise Control of Speed and Position  Longevity  Low Maintenance Just to name a few...

“Moving Ahead” 2009 Stepper Motors have many Advantages…  Inherently Lower Cost  Do Not Require Tuning  Excellent Low Speed Torque Can often eliminate need for additional gearingCan often eliminate need for additional gearing  Long Life Bearings are the only mechanical wear pointBearings are the only mechanical wear pointBut….

“Moving Ahead” 2009 Stepper Motors have had several Disadvantages…  Stepper Motors Can Lose Synchronization Lose the ability to produce torqueLose the ability to produce torque  They Tend to Run Hot The use of phase current is independent of loadThe use of phase current is independent of load  Cannot operate as a Torque Regulator Excessive Lead or Lag causes lose of synchronizationExcessive Lead or Lag causes lose of synchronization Until Now…

“Moving Ahead” 2009 Introducing

“Moving Ahead” 2009 What is AccuStep ?  AccuStep is a revolutionary control technology that, when applied to stepping motors, prevents the loss of synchronization due to transient overload, extreme acceleration or deceleration, or excessive slew speed.

“Moving Ahead” 2009  In a stepper motor, the Torque is a function of the phase current and the angular displacement between the rotor and stator fields.  Maximum torque is produced when the rotor tooth is one step to the left or right of the stable equilibrium point. How Does AccuStep Work?

“Moving Ahead” 2009  AccuStep regulates the stator field position in relation to the rotor position  By controlling the offset, the maximum available torque is available under all conditions How Does AccuStep Work?

“Moving Ahead” 2009 How Does AccuStep Work?  AccuStep uses the encoder to monitors the location of the rotor relative to the stator field in terms of motor steps.  If the error is less than a Control Bounds, AccuStep does nothing  As the offset approaches a Control Bounds AccuStep will intervene to prevent loss of synchronization.  This is achieved by intelligently managing how steps are issued such that the rotor and stator positions stay within bounds.

“Moving Ahead” 2009 Benefits Over Conventional Stepper Motors  Eliminates stalls and generates smooth movement even if the motor is overdriven in either direction. No need to de-rate the motor.No need to de-rate the motor.

“Moving Ahead” 2009 Benefits Over Conventional Stepper Motors  Better tracking performance Can insert missed steps during move instead of once move is complete.Can insert missed steps during move instead of once move is complete. Makes move times under varying conditions more repeatableMakes move times under varying conditions more repeatable

“Moving Ahead” 2009 Benefits Over Conventional Stepper Motors  Enhances the motor’s capability to handle inertia mismatches and sudden transient changes. Performs well with compliant loadsPerforms well with compliant loads

“Moving Ahead” 2009 Benefits Over Conventional Stepper Motors  Variable Operating Current Adjusts the operating current from 2 % up to 100 % of a defined maximum based on the motor lag / lead from 0 to 1 full step.Adjusts the operating current from 2 % up to 100 % of a defined maximum based on the motor lag / lead from 0 to 1 full step. This is done dynamically during a moveThis is done dynamically during a move The operating current is increased immediately when lag / lead increases but is decreased slower using a filtering algorithmThe operating current is increased immediately when lag / lead increases but is decreased slower using a filtering algorithm Useful to reduce heat when the torque requirement is generally modest.Useful to reduce heat when the torque requirement is generally modest.

“Moving Ahead” 2009 Benefits Over Conventional Stepper Motors  Torque Mode When in torque mode an offset between the rotor and stator of 1 full step will try to be maintained to create a torque on the rotor. If the load applied to the rotor is less then the torque required to maintain a 1 full step offset the rotor will begin to rotate. The speed of rotation will vary dependent on load. Rotational speed will increase until such time a 1 full step phase shift between the rotor and stator is achieved.When in torque mode an offset between the rotor and stator of 1 full step will try to be maintained to create a torque on the rotor. If the load applied to the rotor is less then the torque required to maintain a 1 full step offset the rotor will begin to rotate. The speed of rotation will vary dependent on load. Rotational speed will increase until such time a 1 full step phase shift between the rotor and stator is achieved.

“Moving Ahead” 2009 Benefits Over Conventional Stepper Motors  Torque Mode (cont.) This allows for steppers to operate in areas previously reserved for servo or brush DC motors.This allows for steppers to operate in areas previously reserved for servo or brush DC motors. Eliminates the need for a servo in many applications, and enhances the stepper’s benefits of stiffness, high starting torque, and low speed stability.Eliminates the need for a servo in many applications, and enhances the stepper’s benefits of stiffness, high starting torque, and low speed stability.

“Moving Ahead” 2009 Benefits Over Servo Motors  No tuning required.  High Starting Torque  Handles loads that fluctuate, no matter how quickly they change  Lower cost!

“Moving Ahead” 2009 Let’s Review: Stepper Motors have had several Disadvantages? “Stepper Motors Can Lose Synchronization” prevents the loss of synchronization due to transient overload, extreme acceleration or deceleration, or excessive slew speed

“Moving Ahead” 2009 Let’s Review: Stepper Motors have had several Disadvantages? “Stepper Motors Tend to Run Hot” allows for Variable Operating Current which can provide higher currents only as required by the process, thereby lowering the general operating temperature

“Moving Ahead” 2009 Let’s Review: Stepper Motors have had several Disadvantages? “Steppers Cannot operate as a Torque Regulator” includes Torque Mode Operation. This allows for steppers to operate in areas previously reserved for servo or brush DC motors. includes Torque Mode Operation. This allows for steppers to operate in areas previously reserved for servo or brush DC motors.