On the other hand, when the motor inertia is bigger than the load inertia, the electric motor will require more power than is otherwise necessary for the particular application. This boosts costs because it requires paying more for a engine that’s bigger than necessary, and because the increased power consumption requires higher operating costs. The solution is to use a gearhead to complement the inertia of the electric motor to the inertia of the strain.
Recall that inertia is a way of measuring an object’s level of resistance to improve in its motion and is a function of the object’s mass and shape. The greater an object’s inertia, the more torque is needed to accelerate or decelerate the thing. This implies that when the load inertia is much bigger than the electric motor inertia, sometimes it can cause excessive overshoot or boost settling times. Both circumstances can decrease production range throughput.
Inertia Matching: Today’s servo motors are generating more torque in accordance with frame size. That’s because of dense copper windings, lightweight materials, and high-energy magnets. This creates higher inertial mismatches between servo motors and the loads they are trying to move. Using 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 more responsive servo gearhead system that’s easier to tune. Again, this is accomplished through the gearhead’s ratio, where in fact the reflected inertia of the load to the motor 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. Finding the ideal pairing must take into account many engineering considerations.
So how does a gearhead go about providing the energy required by today’s more demanding applications? Well, that all goes back to the basics of gears and their ability to modify the magnitude or path of an applied drive.
The gears and number of teeth on each gear create a ratio. If a engine can generate 20 in-pounds. of torque, and a 10:1 ratio gearhead is attached to its result, the resulting torque will be near to 200 in-lbs. With the ongoing emphasis on developing smaller footprints for motors and the equipment that they drive, the ability to pair a smaller electric motor with a gearhead to attain the desired torque result is invaluable.
A motor could be rated at 2,000 rpm, however your application may only require 50 rpm. Trying to run the motor at 50 rpm might not be optimal predicated on the following;
If you are working at a very low speed, such as for example 50 rpm, as well as your motor feedback quality isn’t high enough, the update rate of the electronic drive may cause a velocity ripple in the application. For example, 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 control the motor includes a velocity loop of 0.125 milliseconds, it will look for that measurable count at every 0.0375 degree of shaft rotation at 50 rpm (300 deg/sec). When it generally does not discover that count it will speed up the electric motor rotation to find it. At the speed that it finds another measurable count the rpm will become too fast for the application and the drive will slower the engine rpm back off to 50 rpm and the complete process starts yet again. This constant increase and decrease in rpm is exactly what will cause velocity ripple in an application.
A servo motor operating at low rpm operates inefficiently. Eddy currents are loops of electrical current that are induced within the engine during operation. The eddy currents actually produce a drag drive within the engine and will have a larger negative impact on motor functionality at lower rpms.
An off-the-shelf motor’s parameters might not be ideally suited to run at a minimal rpm. When an application runs the aforementioned motor at 50 rpm, essentially it is not using all of its obtainable rpm. As the voltage constant (V/Krpm) of the motor is set for a higher rpm, the torque constant (Nm/amp), which is usually directly linked to it-is usually lower than it requires to be. Because of this 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 occasionally called gear reducers. Utilizing a gearhead with a 40:1 ratio, the engine rpm at the insight of the gearhead will be 2,000 rpm and the rpm at the output of the gearhead will become 50 rpm. Working the electric motor at the bigger rpm will permit you to avoid the issues mentioned in bullets 1 and 2. For bullet 3, it allows the design to use much less torque and current from the electric motor based on the mechanical benefit of the gearhead.