QuickSilver Controls has released the X-series 34 Frame SilverMax Integrated Servo Motor Family. This extends the company's hybrid servo product line.

QCI-X34 series operate from 12.5 v to 72 v (processor section 12 v to 48 v). Mechanical power out levels up to 850 W. X34CK-1 and -2, and X34CT-1 have been added as a lower cost option for the mid power range.The X34HC-x family covers the upper power and torque range. These hybrid servos use advanced techniques to obtain a high efficiency of up to 80 percent over up to a 4:1 speed range (greater than 70 percent over a 10:1 speed range)This is including both the motor and the driver. This is the result of a combination of a very high torque constant motor with a very low winding resistance, and the application of field-weakening techniques. The high torque constant allows this motor to produce full continuous power by 500 rpm for the 48 v drive level, and to continue this same power level through 2,000 rpm. 

These hybrid servo motors are designed with an interior permanent magnet rotor (also called buried magnet), allowing for field weakening. This lets us extend the high efficiency operation over a wide range by effectively turning down the torque constant to enable higher speed operation at a given voltage. Keeping the motor back-EMF near the input voltage over a wide range of speeds.In contrast, conventional servo motors use low permeability face mounted magnets in in their rotors which make it much more difficult to use field weakening techniques, thus their region of high efficiency operation is limited to very near their optimal speed where back-EMF nears the input voltage. Operate conventional servos at 20 percent of their optimal speed, and they will have 20 percent of their optimal efficiency at best. Operate conventional servo motors them at peak torque and their heating rapidly increases – to the point that they can only sustain for typically a few seconds – and their efficiency plummets. (Both motors compared at 48 VDC; peak torque for conventional motor equaled the continuous torque rating of the X34HC-1 system.)

This means if you are using most conventional servo motors to direct drive a belt or lead screw applications, then it is likely the motor will not be near their power rating, and the efficiency will be poor. Peak torque for conventional servos will typically be available for only a brief 1 to 5 seconds before the windings are nearing maximum temperature. This is not surprising as conventional servo motors get their peak torque by overdriving the motor by a factor of 3x to 10x the sustainable current – which causes 9x to 100x the resistive heating as compared to their continuous current rating. The hybrid servo, alternatively, produces high torques in direct dive operations while running at their nominal continuous currents.