User Manual SCA-LE-30-03
ElectroCraft
®
E-Mail: [email protected] www.electrocraft.com May 2009
22
Open-loop
A system in which there is no feedback. Motor motion is expected to faithfully follow the
input command. Stepping motor systems are an example of open-loop control.
Pulse Width Modulation (PWM)
1. A PWM controller (amplifier) switches DC supply voltage on and off at fixed frequencies.
The length of the on/off interval or voltage waveform is variable.
2. Pulse width modulation (PWM), describes a switch-mode (as opposed to linear) control
technique used in amplifiers and drivers to control motor voltage and current. PWM offers
greatly improved efficiency compared to linear techniques.
Ramp
The ramp time defines the increasing time to reach the scheduled value. The ramp is active
after the drive is enabled, also after changing the
Set value
.
Regeneration
The action during motor braking, in which the motor acts as a generator and takes kinetic
energy from the load, converts it to electrical energy, and returns it to the amplifier.
Resonance
Oscillatory behaviour caused by mechanical limitations.
Ringing
Is an oscillation of a system following a sudden change in state.
Speed
Describes the linear or rotational velocity of a motor or other object in motion.
Tachometer
A small generator normally used as a rotational speed sensing device. The tachometer
feeds its signal to a control which adjusts its output to the motor accordingly (called "closed
loop feedback" control).