However, when the motor inertia is bigger than the load inertia, the engine will require more power than is otherwise necessary for this application. This increases costs because it requires spending more for a motor that’s bigger than necessary, and because the increased power usage requires higher working costs. The solution is to use a servo gearhead gearhead to complement the inertia of the motor to the inertia of the load.
Recall that inertia is a measure of an object’s resistance to improve in its motion and is a function of the object’s mass and form. The greater an object’s inertia, the more torque is needed to accelerate or decelerate the thing. This implies that when the strain inertia is much larger than the electric motor inertia, sometimes it could cause excessive overshoot or boost settling times. Both conditions can decrease production line throughput.
Inertia Matching: Today’s servo motors are producing more torque relative to frame size. That’s due to dense copper windings, light-weight materials, and high-energy magnets. This creates greater inertial mismatches between servo motors and the loads they are trying to move. Utilizing a gearhead to better match the inertia of the engine to the inertia of the load allows for utilizing a smaller electric motor and results in a far more responsive system that is easier to tune. Again, this is achieved through the gearhead’s ratio, where in fact the reflected inertia of the load to the engine is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers producing smaller, yet better motors, gearheads have become increasingly essential partners in motion control. Locating the optimal pairing must take into account many engineering considerations.
So how will a gearhead go about providing the energy required by today’s more demanding applications? Well, that all goes back to the fundamentals of gears and their ability to alter the magnitude or direction of an applied pressure.
The gears and number of teeth on each gear create a ratio. If a engine can generate 20 in-lbs. of torque, and a 10:1 ratio gearhead is mounted on its output, the resulting torque will be near to 200 in-pounds. With the ongoing emphasis on developing smaller footprints for motors and the gear that they drive, the capability to pair a smaller electric motor with a gearhead to achieve the desired torque output is invaluable.
A motor may be rated at 2,000 rpm, but your application may only require 50 rpm. Attempting to run the motor at 50 rpm may not be optimal predicated on the following;
If you are running at a very low rate, such as 50 rpm, and your motor feedback resolution isn’t high enough, the update rate of the electronic drive could cause a velocity ripple in the application form. For instance, with a motor feedback resolution of 1 1,000 counts/rev you have a measurable count at every 0.357 degree of shaft rotation. If the electronic drive you are employing to control the motor has a velocity loop of 0.125 milliseconds, it will look for that measurable count at every 0.0375 amount of shaft rotation at 50 rpm (300 deg/sec). When it generally does not find that count it will speed up the electric motor rotation to find it. At the quickness that it finds the next measurable count the rpm will become too fast for the application and then the drive will slow the engine rpm back down to 50 rpm and the complete process starts yet again. This continuous increase and reduction in rpm is exactly what will cause velocity ripple in an application.
A servo motor working at low rpm operates inefficiently. Eddy currents are loops of electric current that are induced within the electric motor during operation. The eddy currents actually produce a drag power within the electric motor and will have a larger negative effect on motor performance at lower rpms.
An off-the-shelf motor’s parameters may not be ideally suitable for run at a minimal rpm. When a credit card applicatoin runs the aforementioned engine at 50 rpm, essentially it is not using most of its available rpm. Because the voltage constant (V/Krpm) of the electric motor is set for a higher rpm, the torque constant (Nm/amp), which is definitely directly related to it-is definitely lower than it needs to be. Because of this the application needs more current to drive it than if the application form had a motor particularly created for 50 rpm.
A gearheads ratio reduces the electric motor rpm, which explains why gearheads are sometimes called gear reducers. Utilizing a gearhead with a 40:1 ratio, the electric motor rpm at the insight of the gearhead will become 2,000 rpm and the rpm at the output of the gearhead will be 50 rpm. Working the motor at the higher rpm will enable you to avoid the worries mentioned in bullets 1 and 2. For bullet 3, it allows the design to use much less torque and current from the engine predicated on the mechanical advantage of the gearhead.