Spindle motor and drives - For High frequence motors

Spindle motor and drive

Hello,

Welcome to the AC Drive Page for Spindle Motors!

Dear members, as you know, high-speed motors require high-frequency power supply. In the market, especially in local machines, motor varieties ranging from 200-300 Hz are commonly used.

For such motors, "Standard VFD" have been successfully performing and operating without any problems in various machines in the industry for many years.

So, What is the Difference in Our Spindle Drives?

Particularly in metalworking machines (CNC), spindle motor systems perform two separate tasks:

1- Taking standard chips by operating at high speeds

2- Positioning on a specific point on the material surface with servo motor precision to perform an operation, using the same motor

At this point, there is no need to use the models below for spindle motors used in standard vertical machining or woodworking CNC systems, or saws.

High-frequency motors are not only preferred in CNC machines but also in many machine systems serving the industrial automation sector.

What Should I Pay Attention To?

When selecting a speed control device for an existing motor and load, it is not the correct method to consider only the motor's kW value. In reality, it is necessary to examine the characteristics of the load that the motor will drive and the overload period. Therefore, the loadability performance of the driver is an essential criterion.

What Does Constant Torque Load Mean?

It is the type of load where the motor load curve remains constant according to the circuit up to the field weakening point, meaning the power changes proportionally with speed. If we look at the load curve according to the circuit, the load torque and motor current remain constant, but the motor power and line current at the driver input change linearly according to the circuit.

Why Does the Load Curve Remain Constant?

Our motor is lifting a mass with a known weight. Let's always remember the following formula: Fv = Tw, Fwd/2 = Tw, T = Fd/2. Since the force F (mg) is constant and the radius of our pulley does not change, T remains constant. P = Tw = T2πn/60. Here, as n changes, P changes. When we raise our motor above its nominal speed, the torque decreases, but the motor current, line current, and motor power remain constant.

As a result, in these types of applications, since the motor current generally remains constant, we can select the speed control device from %130 loadability.

What are These Types of Loads?

In systems such as high-speed rotating conveyors, screw compressors, lifting-lowering systems (excluding cranes), and extruders, we encounter these types of loads. However, extruders require high torque at startup; professional application devices are needed to provide this.

Applications where the motor load curve changes quadratically according to the speed and, therefore, the power changes proportionally to the cube of the speed. Motor current and line current exhibit the same characteristics as the load curve.

Loads with this type of characteristic are very high-speed compressors, pumps, fans, and mixers. In these applications, we can also select the speed control device from %130 loadability.

Please Note: The currents here are given for an ambient temperature of 40°C and a triggering frequency of 4 kHz. Many manufacturers' catalogs provide similar technical specifications. However, another essential point to pay attention to is the level to which the device's continuous output current decreases when the ambient temperature increases.

This is precisely where the quality difference of our spindle motor drives is needed. A %1 current reduction is anticipated for each degree up to 60°C.