Variable frequency drives convert AC input voltage to DC, and then back to pulse-width-modulated AC voltage with variable frequency. These AC voltage pulses are controlled by insulated gate bipolar transistors (IGBTs). IGBTs have a fast switching time (also referred to as “rise time” or “dv/dt”—rate of change of voltage over time), which reduces energy losses […]
FAQs + basics
Warner XS-Series brake applications: Quiet and powerful braking in airline seats and more
XS-Series spring-actuated electrically released brakes from Warner Electric — part of the Altra Industrial Motion Corp. — are specifically designed to meet stringent compactness requirements in weight-sensitive applications. They boost reliable braking performance in a package weighing as little as 27 g. The XS brakes are also statically engaged holding so can stop moving loads in […]
What are gearmotors used for position-control applications?
Gearmotors are often used in position control applications. A prime example would be in packaging or material handling where a load needs to be picked up or placed at a specified location, or applications with more precise requirements such as micro-positioning in high-precision manufacturing or dispensing. Application requirements will dictate the level of accuracy needed […]
Motion-platform maker standardizes on Sensoray I/O for measurement and control
Servos & Simulation Inc. is a manufacturer of motion platforms and control loaders. Recently the systems builder picked a Model 826 analog and digital I/O system on a PCI Express board from Oregon-based Sensoray for the primary measurement and control interface for their full product line. Servos & Simulation provides motion platforms and control loaders […]
What’s to know about analog and digital I/O for PLCs?
Common PLC input/output (I/O) can be analog and/or digital. An analog signal is one whose value continually varies over time. They are best represented as a continuous signal like a sine wave. Each point on the wave has a precisely defined value. For example, analog inputs for PLCs can include signals from pressure transducers and […]
Current state of programmable automation controllers (PACs) for motion
Programmable automation controllers (PACs) excel in commanding complex automation setups that involve PC-based and HMI functions as well as process control (largely because of the way they handle I/O). PACs are also increasingly common in motion applications for machining or handling discrete product thanks to the flexibility and interoperability they offer machine designs. Today’s PACs […]
How are servo system velocity control loops tuned?
Servo systems typically use a combination of three types of control loops: current, velocity, and position. The velocity control loop serves two purposes—it enables the system to respond to changing velocity commands, and it allows the system to resist high-frequency load disturbances. But the velocity loop by itself can’t ensure that the system maintains a […]
What are Instruction Lists (ILs) for PLC programming?
Instruction lists (or ILs) are one of the five PLC programming languages defined by the IEC 61131-3 standard. (The others being ladder logic diagrams, function block diagrams, sequential function charts, and structured text.) ILs are not a graphical programming language. Instead, they most resemble assembly language programming. As the name implies, a program is a […]
What are the differences between slotted and slotless motors?
The original brushless DC (BLDC) motors were designed with slotted stators, and the majority of BLDC motors are still made this way. But this design produces cogging torque, which makes it difficult to achieve smooth motion, especially at slow speeds. To eliminate this effect, a new design was developed, eliminating the slots in the stator (which […]
How to determine actual gearmotor horsepower?
Even though electric motors have been around for a long time, they still are the cause of much perplexity, especially surrounding key parameters such as frame size, torque, and horsepower. And gearmotors can add an extra dimension of confusion. Specifically, when we say gearmotor, we’re talking about the entire unit; the motor and gearing combined. […]