However, when the engine inertia is larger than the load inertia, the motor will require more power than is otherwise essential for this application. This increases costs since it requires spending more for a electric motor that’s bigger than necessary, and since the increased power intake requires higher operating costs. The solution is to use a gearhead to complement the inertia of the electric 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 shape. The higher an object’s inertia, the more torque is needed to accelerate or decelerate the object. This implies that when the load inertia is much larger than the motor inertia, sometimes it can cause excessive overshoot or increase settling times. Both conditions can decrease production series throughput.
Inertia Matching: Today’s servo motors are producing more torque relative to 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 want to move. Utilizing a gearhead to raised match the inertia of the motor to the inertia of the load allows for using a smaller electric motor and outcomes in a far more responsive system that is simpler to tune. Again, that is attained through the gearhead’s ratio, where in fact the reflected inertia of the strain to the electric motor is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers generating smaller, yet more powerful motors, gearheads have become increasingly essential companions in motion control. Locating the optimal pairing must consider many engineering considerations.
So how will a gearhead start providing the energy 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 force.
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 output, the resulting torque will certainly be close to 200 in-pounds. With the ongoing focus on developing smaller sized footprints for motors and the gear that they drive, the capability to pair a smaller motor with a gearhead to attain the desired torque servo gearhead result is invaluable.
A motor may be rated at 2,000 rpm, but 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 running at an extremely low acceleration, such as 50 rpm, and 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 possess a measurable count at every 0.357 amount of shaft rotation. If the digital drive you are employing to regulate the motor has a velocity loop of 0.125 milliseconds, it’ll search 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’ll speed up the motor rotation to think it is. At the velocity that it finds the next measurable count the rpm will end up being too fast for the application form and then the drive will gradual the electric motor rpm back off to 50 rpm and then the complete process starts yet again. This continuous increase and reduction in rpm is what will cause velocity ripple within an application.
A servo motor running at low rpm operates inefficiently. Eddy currents are loops of electrical current that are induced within the motor during operation. The eddy currents in fact produce a drag force within the electric motor and will have a larger negative effect on motor performance at lower rpms.
An off-the-shelf motor’s parameters might not be ideally suited to run at a low rpm. When an application runs the aforementioned engine at 50 rpm, essentially it is not using most of its offered rpm. As the voltage constant (V/Krpm) of the engine is set for an increased rpm, the torque continuous (Nm/amp), which can be directly related to it-is definitely lower than it needs to be. As a result the application requirements more current to operate a vehicle it than if the application form had a motor specifically designed for 50 rpm.
A gearheads ratio reduces the motor rpm, which is 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 result of the gearhead will end up being 50 rpm. Working the motor at the higher rpm will permit you to avoid the concerns mentioned in bullets 1 and 2. For bullet 3, it enables the design to use less torque and current from the electric motor based on the mechanical advantage of the gearhead.