On the other hand, when the engine inertia is larger than the strain inertia, the motor will require more power than is otherwise essential for this application. This increases costs since it requires having to pay more for a electric 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 electric motor to the inertia of the load.
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 needed to accelerate or decelerate the thing. This means that when the strain inertia is much bigger than the motor inertia, sometimes it can cause excessive overshoot or enhance settling times. Both circumstances can decrease production series 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 want to move. Using a gearhead to raised match the inertia of the engine to the inertia of the strain 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 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 companions in motion control. Locating the optimal pairing must consider many engineering considerations.
So how really does a gearhead start 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 force.
The gears and number of teeth on each gear servo gearhead create a ratio. If a motor can generate 20 in-pounds. of torque, and a 10:1 ratio gearhead is attached to its output, the resulting torque will certainly be close to 200 in-lbs. With the ongoing emphasis on developing smaller sized footprints for motors and the equipment that they drive, the capability to pair a smaller engine with a gearhead to achieve the desired torque output is invaluable.
A motor could 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 working at an extremely low rate, such as for example 50 rpm, as well as your motor feedback resolution isn’t high enough, the update rate of the electronic drive could cause a velocity ripple in the application. For example, with a motor feedback resolution of 1 1,000 counts/rev you have a measurable count at every 0.357 amount of shaft rotation. If the electronic drive you are employing to control the motor includes 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 does not discover that count it’ll speed up the electric motor rotation to think it is. At the rate that it finds the next measurable count the rpm will end up being too fast for the application form and the drive will slower the motor rpm back down to 50 rpm and the complete process starts all over 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 electric current that are induced within the engine during operation. The eddy currents in fact produce a drag push within the engine and will have a greater negative effect on motor overall performance at lower rpms.
An off-the-shelf motor’s parameters might not be ideally suitable for run at a minimal rpm. When an application runs the aforementioned electric motor at 50 rpm, essentially it isn’t using all of its offered rpm. As the voltage continuous (V/Krpm) of the engine is set for a higher rpm, the torque constant (Nm/amp), which is certainly directly linked to it-is usually lower than it requires to be. As a result the application requirements more current to drive it than if the application form had a motor particularly created for 50 rpm.
A gearheads ratio reduces the engine rpm, which is why gearheads are occasionally called gear reducers. Utilizing a gearhead with a 40:1 ratio, the motor rpm at the insight of the gearhead will be 2,000 rpm and the rpm at the output of the gearhead will be 50 rpm. Operating the engine at the bigger rpm will allow you to avoid the concerns mentioned in bullets 1 and 2. For bullet 3, it enables the design to use much less torque and current from the motor predicated on the mechanical benefit of the gearhead.