On the other hand, when the engine inertia is larger than the load inertia, the motor will require more power than is otherwise necessary for this application. This improves costs because it requires having to pay more for a motor that’s bigger than necessary, and because the increased power usage requires higher operating costs. The solution is to use a gearhead to match the inertia of the engine to the inertia of the load.
Recall that inertia is a way of measuring an servo gearhead object’s resistance to improve in its movement 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 means that when the load inertia is much bigger than the motor inertia, sometimes it could cause excessive overshoot or boost settling times. Both conditions can decrease production range throughput.
Inertia Matching: Today’s servo motors are generating more torque relative to frame size. That’s because of dense copper windings, lightweight materials, and high-energy magnets. This creates greater inertial mismatches between servo motors and the loads they are trying to move. Using a gearhead to raised match the inertia of the motor to the inertia of the load allows for using a smaller electric motor and results in a far more responsive system that’s easier to tune. Again, that 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 generating smaller, yet more powerful motors, gearheads have become increasingly essential partners in motion control. Locating the optimum pairing must take into account many engineering considerations.
So how really does a gearhead go about providing the energy required by today’s more demanding applications? Well, that all goes back again to the basics of gears and their ability to change the magnitude or direction of an applied push.
The gears and number of teeth on each gear create a ratio. If a electric motor can generate 20 in-lbs. of torque, and a 10:1 ratio gearhead is mounted on its result, the resulting torque can be close to 200 in-lbs. With the ongoing emphasis on developing smaller sized footprints for motors and the gear that they drive, the capability to pair a smaller motor with a gearhead to achieve the desired torque result is invaluable.
A motor could be rated at 2,000 rpm, but your application may just require 50 rpm. Trying to perform the motor at 50 rpm might not be optimal based on the following;
If you are operating at an extremely low rate, such as for example 50 rpm, and your motor feedback resolution is not high enough, the update price of the electronic drive may cause a velocity ripple in the application. For instance, with a motor opinions resolution of just one 1,000 counts/rev you have a measurable count at every 0.357 amount of shaft rotation. If the electronic drive you are using to regulate the motor has a velocity loop of 0.125 milliseconds, it will search for that measurable count at every 0.0375 degree of shaft rotation at 50 rpm (300 deg/sec). When it does not discover that count it’ll speed up the motor rotation to think it is. At the velocity that it finds the next measurable count the rpm will become too fast for the application and the drive will slower the motor rpm back off to 50 rpm and then the whole process starts yet again. This constant increase and reduction in rpm is what will trigger velocity ripple within an application.
A servo motor running at low rpm operates inefficiently. Eddy currents are loops of electric current that are induced within the motor during procedure. The eddy currents in fact produce a drag force within the engine and will have a larger negative impact on motor functionality at lower rpms.
An off-the-shelf motor’s parameters may not be ideally suited to run at a low rpm. When a credit card applicatoin runs the aforementioned electric motor at 50 rpm, essentially it isn’t using most of its available rpm. Because the voltage constant (V/Krpm) of the engine is set for an increased rpm, the torque continuous (Nm/amp), which is certainly directly linked to it-is usually lower than it needs to be. Consequently the application needs more current to drive it than if the application had a motor particularly made for 50 rpm.
A gearheads ratio reduces the electric motor rpm, which explains why gearheads are sometimes called gear reducers. Using a gearhead with a 40:1 ratio, the engine rpm at the input of the gearhead will end up being 2,000 rpm and the rpm at the result of the gearhead will be 50 rpm. Working the electric motor at the higher rpm will permit you to prevent the problems mentioned in bullets 1 and 2. For bullet 3, it allows the design to use much less torque and current from the motor based on the mechanical benefit of the gearhead.