Servo Motors

Servo Motors

Servo Motors are used for various applications. A Servo Motor is a rotary or linear actuator that allows for precise control of angular or linear position, velocity and acceleration. It consists of a suitable motor coupled to a sensor for position feedback. All Servo Motors require a Servo Drive.

Servo Motors are relatively small but very powerful and very energy-efficient. When the shaft of the motor is at the desired position, the power supply to the motor is stopped. If not, the motor is turned in the appropriate direction. The desired position is sent via electrical pulses through the signal wire. The motor's speed is proportional to the difference between its actual position and desired position. So if the motor is near the desired position, it will turn slowly, otherwise it will turn fast. This is called proportional control. This means the motor will only run as hard as necessary to accomplish the task at hand, resulting in an extremely efficient setup.

Yaskawa Servo Pack

Types of Servo Motor


There are two types of servo motors - AC and DC. AC Servo can handle higher current surges and tend to be used in industrial machinery. DC Servos are not designed for high current surges and are usually better suited for smaller applications.

DC motors tend to be less less expensive than their AC counterparts. These Servo Motors have been built specifically for continuous rotation, making it an easy way to get your appliance moving. They feature two ball bearings on the output shaft for reduced friction and easy access to the rest-point adjustment potentiometer.

How is a Servo Motor Controlled?


Servos are controlled by sending an electrical pulse of variable width, or pulse width modulation (PWM), through the control wire. There is a minimum pulse, a maximum pulse, and a repetition rate. A servo motor can usually only turn 90° in either direction for a total of 180° movement. The motor's neutral position is defined as the position where the servo has the same amount of potential rotation in the both the clockwise or counter-clockwise direction.

The PWM sent to the motor determines position of the shaft, and based on the duration of the pulse sent via the control wire; the rotor will turn to the desired position. The servo motor expects to see a pulse every 20 milliseconds (ms) and the length of the pulse will determine how far the motor turns. For example, a 1.5ms pulse will make the motor turn to the 90° position. Shorter than 1.5ms moves it in the counter clockwise direction toward the 0° position, and any longer than 1.5ms will turn the servo in a clockwise direction toward the 180° position.

Control Techniques Servo Motors

Control Techniques offers a wide range of reliable Servo Motors designed to meet specific application requirements. When matched to a Control Techniques' brand servo drive product (Unidrive M, Digitax ST, Epsilon EP or MDS servo drive), the resulting drive/motor combination provides an optimized system in terms of ratings, performance, cost and ease of use.

Why Choose A Control Techniques Servo Motor

  • A full range of servo motors up to 1200 lb-in
  • Single-source motion control lowers total system costs
  • High-speed, peer-to-peer communications
  • Integrated programs eliminate need for PLC
  • Complimentary software offers the ultimate programming capability and greatly reduces programming time

Simple Commissioning & Maintenance

Some motors fitted with high-resolution SinCos or absolute encoders are pre-loaded with the motor “electronic nameplate” data during the manufacturing process. This data can be read by most Control Techniques' brand servo drives and used to automatically optimize the drive settings. This feature simplifies commissioning and maintenance, ensures consistent performance and saves time.

FM Servo Motor
FM Servo Motor1
FM Servo Motor2
FM Servo Motor3

A Motor for Every Situation

Unimotor FM Range

FM Servo Motor

Unimotor FM is a high performance, brushless AC Servo motor range matched for use with Control Techniques' brand drives. “FM” stands for “Flexible Motor” and is designed to accommodate a wide range of applications. The motors are available in six frame sizes with various mounting arrangements and motor lengths. IP65 conformance, sealed against water spray and dust when mounted and connected.

Unimotor HD Range


Designed for maximum torque density, the Unimotor HD brushless AC Servo motor series provides an exceptionally compact, low inertia solution for applications that require very high torque during rapid acceleration and deceleration profiles. Unimotor HD are fitted with SinCos and the electronic nameplate system which has the benefits listed above. The Unimotor HD torque profile is closely matched to Digitax ST Servo drives providing up to 300% peak overload for maximum dynamic performance.

NT Motor Range


The NT motor is a compact, high performance brushless AC servo motor designed to maximize torque and minimize size. The NT motor uses powerful Neodymium magnets and is manufactured with a segmented core to maximize stator efficiency – cable lengths up to 20 ft are available. Now available with multiple feedback options and white epoxy food-grade finish, the NT motor is an economical, high-performance motor made to maximize torque and minimize size.

XV Motor Range


The XV Motor is a high performance, low-inertia and high-torque brushless AC servo motor in a compact economical package – ideal for high-volume applications. UL recognized, CE approved and RoHS compliant, XV Motors offer low-cost solutions with the features of a premium-priced servo offering. Intended for higher throughputs and smaller machines, XV Motors are available in 4 frame sizes: 40, 60, 80 and 130 mm with speeds ranging from 2000 to 5000 rpm. Applications with continuous torque requirements up to 101 lb-in (11.4 Nm) are the perfect match for XV Motors.

# Unimotor FM Unimotor HD NT Motor Series XV Motor Series
Drive Voltage 230V / 460V 230V / 460V 230V 230V
Continuous Stall Torque Up to 1204 lb-in Up to 752 lb-in Up to 56 lb-in Up to 101 lb-in
Flange IEC (NEMA Option) IEC IEC, NEMA Metric
Frame 75, 95, 115, 142, 190, 250 mm 55, 67, 89, 115, 142, 190 mm 2 3in 40, 60, 80, 130 mm
Inertia Medium (High Inertia Option Available) Low Low Low, Medium
Peak Torque Up to 3611 lb-in Up to 2257 lb-in Up to 144 lb-in Up to 301 lb-in
Base Speeds Up to 6000 rpm Up to 6000 rpm Up to 5000 rpm Up to 5000 rpm

Yaskawa Servo Motors

Sigma-5 & Sigma-7 rotary Yaskawa Servo motors feature a wide range of outputs from 3W - 55kW. Both low and medium inertia models are available with 20-bit absolute encoders standard on all models. Our new tuning-less function means it works as soon as you hook it up! The Sigma-5 & Sigma-7 Servo Motors offer more performance than ever before, the series advanced autotuning function lets you set up for it rapidly. Compliance with key international standards, a diverse motor line-up, compact size and high speed and simple maintenance; a perfect solution for your Servo Motor requirements!

Existing functions to minimize vibration have been enhanced, and new ones added, improving tracking and further improving settling time. Vibration and noise during driving have also been cut, along with vibration at machine edges when stopping.

Rotary Servo Motors (Small Capacity)

servo motor rotary

Moment of inertia ratio for the Yaskawa servo motors have been doubled in the same motor, reducing the moment of inertia ratio and boosting gain for faster settling. Instantaneous peak torque has been boosted from 300% to 350%, contributing to shorter cycle times. Improved motor constants have reduced both losses and heating.

Rotary Servo Motors (Medium Capacity)

servo motor rotary2

Smaller package and about 20% lighter, but with the same moment of inertia ratio as the conventional model. A small encoder connector is applied. New coupling delivers typical 5G vibration resistance.

Linear Servo Motors

servo motor linear

Yaskawa linear motors are directly coupled to the load, this then accomplishes a very high postioning accuracy and simultaneousness, with smooth motion up to 5m/s. All Yaskawa linear motors are plug and play compatiblewith Sigma-7 and Sigma-5 Servopacks for the best in class performance.

Why Buy from ACDC Drives?

We are happy to answer any questions you have regarding these Yaksawa Servo Motors, so if you do have any questions, just ask! We all know that in the modern workplace often things are needed as fast as possible. That is where we can help. We can also get engineers out to site, to carry out surveys, or to install and commission Yaskawa servo motors on existing or new applications. Call our sales team today by phone on 01905 887 667.

Yaskawa Drives

Need Assistance Working Out Which Servo Motor You Require?

If you need specialist components or just a hand to work out which servo motor would suit what you need then give us a call on 01905 887 667. Our staff are available during office hours and will be happy to help you with any questions.