However, when the motor inertia is larger than the load inertia, the engine will require more power than is otherwise necessary for the particular application. This increases costs since it requires precision gearbox paying more for a motor that’s larger than necessary, and because the increased power usage requires higher operating costs. The solution is by using a gearhead to match 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 change in its motion and is a function of the object’s mass and shape. The higher an object’s inertia, the more torque is required to accelerate or decelerate the thing. This means that when the strain inertia is much bigger than the electric motor inertia, sometimes it could cause extreme overshoot or enhance settling times. Both conditions can decrease production collection throughput.
Inertia Matching: Today’s servo motors are generating more torque relative to frame size. That’s due to 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 electric motor to the inertia of the strain allows for using 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 the reflected inertia of the load to the engine is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers creating smaller, yet more powerful motors, gearheads have become increasingly essential partners in motion control. Finding the ideal pairing must take into account many engineering considerations.
So how will a gearhead go about providing the power required by today’s more demanding applications? Well, that goes back again to the basics of gears and their ability to alter the magnitude or path of an applied power.
The gears and number of teeth on each gear create a ratio. If a motor can generate 20 in-lbs. of torque, and a 10:1 ratio gearhead is attached to its output, the resulting torque will be near to 200 in-lbs. With the ongoing emphasis on developing smaller sized footprints for motors and the equipment that they drive, the ability to pair a smaller engine with a gearhead to achieve the desired torque output is invaluable.
A motor may be rated at 2,000 rpm, however your application may only require 50 rpm. Attempting to perform the motor at 50 rpm may not be optimal based on the following;
If you are operating at a very low speed, such as 50 rpm, as well as your motor feedback resolution is not high enough, the update rate of the electronic drive may cause a velocity ripple in the application form. For example, with a motor opinions resolution of 1 1,000 counts/rev you possess a measurable count at every 0.357 degree of shaft rotation. If the digital drive you are using to regulate the motor has 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 does not find that count it’ll speed up the electric motor rotation to think it is. At the swiftness that it finds the next measurable count the rpm will become too fast for the application and the drive will gradual the electric motor rpm back down to 50 rpm and then the complete process starts yet again. This continuous increase and reduction in rpm is what will cause velocity ripple in an application.
A servo motor operating at low rpm operates inefficiently. Eddy currents are loops of electric current that are induced within the engine during procedure. The eddy currents in fact produce a drag pressure within the motor and will have a greater negative effect on motor overall performance at lower rpms.
An off-the-shelf motor’s parameters may not be ideally suited to run at a minimal rpm. When a credit card applicatoin runs the aforementioned engine at 50 rpm, essentially it isn’t using all of its available rpm. As the voltage continuous (V/Krpm) of the engine is set for an increased rpm, the torque continuous (Nm/amp), which is definitely directly linked to it-is certainly lower than it requires to be. Consequently the application needs more current to drive it than if the application form had a motor specifically designed for 50 rpm.
A gearheads ratio reduces the engine rpm, which is why gearheads are occasionally called gear reducers. Using a gearhead with a 40:1 ratio, the engine rpm at the insight of the gearhead will become 2,000 rpm and the rpm at the result of the gearhead will become 50 rpm. Working the electric motor at the higher rpm will enable you to avoid the concerns mentioned in bullets 1 and 2. For bullet 3, it allows the design to use less torque and current from the electric motor based on the mechanical advantage of the gearhead.