On the other hand, when the electric motor inertia is bigger than the strain inertia, the engine will require more power than is otherwise necessary for this application. This boosts costs because it requires spending more for a engine that’s bigger than necessary, and since the increased power intake requires higher working costs. The solution is to use a precision gearbox gearhead to complement the inertia of the motor to the inertia of the load.
Recall that inertia is a measure of an object’s level of resistance to change in its movement 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 means that when the load inertia is much bigger than the motor inertia, sometimes it can cause excessive overshoot or increase settling times. Both circumstances can decrease production range throughput.
Inertia Matching: Today’s servo motors are producing more torque relative to frame size. That’s because of dense copper windings, light-weight materials, and high-energy magnets. This creates greater inertial mismatches between servo motors and the loads they want to move. Utilizing a gearhead to better match the inertia of the engine to the inertia of the strain 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 motor is decreased by 1/ratio^2.
As servo technology has evolved, with manufacturers producing smaller, yet better motors, gearheads are becoming increasingly essential partners in motion control. Locating the optimum pairing must consider many engineering considerations.
So how does a gearhead go about providing the power required by today’s more demanding applications? Well, that goes back to the basics of gears and their capability to change the magnitude or direction 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 mounted on its result, the resulting torque can be close 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 engine with a gearhead to attain the desired torque result is invaluable.
A motor could be rated at 2,000 rpm, but your application may only require 50 rpm. Trying to perform the motor at 50 rpm might not be optimal predicated on the following;
If you are working at an extremely low acceleration, such as for example 50 rpm, and your motor feedback quality isn’t high enough, the update price of the electronic drive may cause a velocity ripple in the application form. For instance, with a motor feedback 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 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 generally does not observe that count it’ll speed up the motor rotation to find it. At the speed that it finds the next measurable count the rpm will become too fast for the application form and then the drive will slow the motor rpm back off to 50 rpm and the whole process starts all over again. This continuous increase and decrease in rpm is what will cause velocity ripple in an application.
A servo motor working at low rpm operates inefficiently. Eddy currents are loops of electrical current that are induced within the motor during procedure. The eddy currents actually produce a drag push within the engine and will have a larger negative impact on motor efficiency at lower rpms.
An off-the-shelf motor’s parameters might not be ideally suitable for run at a low rpm. When an application runs the aforementioned electric motor at 50 rpm, essentially it is not using most of its obtainable rpm. Because the voltage continuous (V/Krpm) of the electric motor is set for a higher rpm, the torque continuous (Nm/amp), which is certainly directly related to it-is lower than it requires to be. As a result the application requirements more current to operate a vehicle it than if the application had a motor specifically created for 50 rpm.
A gearheads ratio reduces the motor rpm, which is why gearheads are sometimes called gear reducers. Using a gearhead with a 40:1 ratio, the electric motor rpm at the input of the gearhead will end up being 2,000 rpm and the rpm at the output of the gearhead will end up being 50 rpm. Operating the electric motor at the higher rpm will allow you to avoid the issues mentioned in bullets 1 and 2. For bullet 3, it allows the look to use much less torque and current from the motor based on the mechanical advantage of the gearhead.