ETEL IL+/LM Linear Motor Selection and Integration Guide

Typical applications: wafer cutting machines, laser direct imaging (LDI), high-speed surface mount machines, optical inspection scanning tables, bio chip sampling machines, and other lightweight, high-speed, and high-precision scenarios.

2.3 Selection Decision Framework

ETEL's product manual provides a concise "Motor Selection Chart" that arranges the IL+and LM series in two dimensions: "sustained force" and "peak force". When selecting, it is recommended to evaluate according to the following steps:

Thrust requirement: Calculate the maximum acceleration thrust (F=ma) and steady-state uniform thrust (overcoming friction) required for the application. The peak thrust determines the upper limit of motor selection, while the sustained thrust determines the heat dissipation design and thermal management scheme.

Speed and acceleration: Ironless IL+is more suitable for high-speed and high acceleration (>5g), while iron core LM is more suitable for medium and low-speed (<3g) but high thrust scenarios.

Accuracy and smoothness requirements: If nanometer level positioning or extremely low speed ripple (<0.1%) is required, IL+is preferred; If system rigidity and anti-interference ability are more important (such as milling), LM is more suitable.

Voltage and driver compatibility: The LM series typically supports higher bus voltages (such as 300Vdc) and is compatible with DSC2P/DSC2V high-voltage drivers; The IL+series is mostly low voltage (such as 48V or 150V) and requires the use of low voltage drivers such as DSCDP/DSCDL.

Heat dissipation method: High continuous thrust (especially LM) usually requires water cooling or forced air cooling; IL+has stronger natural cooling capacity due to low copper and iron losses.

Interpretation of Key Performance Parameters

Whether it is IL+or LM, ETEL provides detailed performance parameter tables, and engineers need to focus on the following:

3.1 Continuous Force

Defined as the long-term output thrust of a motor at rated temperature rise (usually 100 ℃~120 ℃). This value is greatly affected by heat dissipation conditions - the difference in sustained thrust between natural cooling, air cooling, and water cooling can reach 2-3 times. When selecting, the evaluation must be based on the actual heat dissipation capacity of the application (rather than the ideal value).

3.2 Peak Force

The maximum thrust that a motor can provide in a short period of time is usually limited by the peak current of the driver and the magnetic saturation of the motor. The peak thrust determines the maximum acceleration capability of the system, but the duration is usually only a few seconds, and the I ² t heat accumulation needs to be calculated in conjunction with the duty cycle.

3.3 Force Constant (Kt)

The unit is N/A or N/Arms, representing the thrust generated per ampere of current. The larger Kt, the greater the thrust under the same current, but the back electromotive force constant (Ke) also increases accordingly, limiting the voltage margin at high speeds. When selecting, it is necessary to weigh between "thrust/current" and "thrust/voltage".

3.4 Electrical Time Constant

Determined by inductance (L) and resistance (R) (τ=L/R). The time constant affects the response speed of the current loop - motors with smaller time constants (usually iron core motors with larger inductance and higher τ) require lower current loop bandwidth and are relatively easy to debug; Ironless motors have extremely low inductance and small τ, requiring high current loop bandwidth but faster response.

Integrated debugging with ETEL DSC series servo controllers

IL+/LM linear motors must be used in conjunction with ETEL DSC series (DSC2P, DSC2V, DSCDP, DSCDL, DSCDM) digital position controllers. The two are deeply integrated in design, but hardware selection and software parameter settings still need to be noted:

4.1 Encoder interface matching

IL+/LM motors are typically equipped with high-resolution analog cosine encoders (1Vpp) or EnDat 2.1 absolute encoders. The encoder interface (JC5/JC6) of the DSC controller supports:

Analog encoder (K79=0): K55 (increment per pole cycle) and K77 (interpolation factor) need to be set correctly.

EnDat 2.1 (K79=4): Attention should be paid to cable length limitations (≤ 150m, distributed capacitance 90pF/m) and clock frequency (500kHz).

Selection reminder: If the motor comes standard with an 11 μ App encoder (instead of 1Vpp), it is necessary to confirm whether the hardware version of the DSC controller supports it (some early DSCDPs only support 1Vpp).

4.2 Correspondence between motor parameters and K parameters

After selecting the motor model in the "Drive Setting" tool of ETEL Tools, the following K parameters are automatically loaded:

K54 (pole pairs): The linear motor is fixed at 1.

K55 (increments per magnetic pole cycle): determined by the encoder resolution and K77.

K89 (number of phases and PWM frequency): It needs to be matched with the motor winding connection method (star/delta) and the driver PWM frequency. DSCDL is usually set to 20 (two-phase) or 30 (three-phase), with a PWM frequency of 18kHz.