Overview

Overview

Description

The Drive/Motor Simulation block allows for simulation of a physical motor and drive combination. By attaching an Encoder to the motor shaft, the position of the motor can be obtained.

This block is useful in determining mechanical behavior before a machine is built. Many machine behaviors can be determined by simulating different motors/drive combinations including resonance prediction, motor/drive sizing, servo tuning, and expected servo bandwidth.

For simulation, connect the output of a Torque Demand block to the drive Current command input. This passes the torque command used by MechaWare into a simulated drive/motor.

The Drive/Motor block has two outputs. The first is the motor shaft, refer to the block diagram for making custom mechanical structures. Connect an Encoder to the motor shaft to determine position. The second output is the actual drive current output in Amps.

Drive Parameters

The drive parameters for this block are as follows:

Drive Series Specifies a Kollmorgen Drive series (ie. S200). Drive Model SpecifIies a drive model of the selected Drive Series. Custom Drive Allows a custom drive parameter if a Kollmorgen Drive is not going to be used. Drive V Bus Enter the AC (or DC) voltage to be connected to the drive, this value can limit max velocity. Cont. Current I (A) When using a Kollmorgen Drive, this value is automatically populated. If entering custom drive parameters, enter the Continuous Current Limit (in Amps). Peak Current I (A) When using a Kollmorgen Drive, this value is automatically populated. If entering custom drive parameters, enter the Peak Current Limit (in Amps). Note this will limit the peak torque a simulation can output. Regen R (Ohm) Value of Regen Resistor to be connected to the drive, if a Zero value is entered, it is assumed there is no Regen Resistor used. Motor Inductance When using a Kollmorgen Drive, this value is automatically populated. It provides the user the range of motor inductances the drive supports. This value is not shown when custom drive parameters are entered.

Motor Parameters

The motor parameters for this block are as follows:

Size/Stack/Winding These boxes are used to select a Kollmorgen AKM series motor. To select an AKM 32C, select AKM3 for the Motor Size dropdown, then select 2 for the stack size, and select C for the Winding. This automatically populates the motor parameters with the correct values. Custom Motor Use this checkbox to enter your own custom motor parameters. All values must be entered to ensure an accurate simulation. By selecting a Kollmorgen Motor, all parameters are entered automatically. Max Bus Voltage (VDC) Specifies the maximum DC voltage supplied by the drive that the motor can withstand. If this value is lower than the DC voltage capability, (Based on the Drive Vbus) a warning message is displayed. Motor Ipk (A) Specifies the maximum rated current (in Amps) the Motor can withstand. If the Drive’s Peak Current is higher than this value, a warning message is displayed. Torque Const. Kt (N*m) Specifies the Torque Constant of the motor in Newton*m / amp of current. Peak Torque (N-m) The peak torque the motor can apply to a load. Inductance L-L (H) Specifies the Line to Line inductance of the motor, value is in Henries. Inductance L-L (Ohms) Specifies the Line to Line resistance of the motor, value is in Ohms. Rotor Inertia (Kg*m2) Specifies the Rotor Inertia of the motor, in Kg*m². Viscous Damping (N*m/krpm) Specifies the Viscous Damping (Viscous Friction) of the motor, in N*m/ per thousand rpm. Static Friction Tf (N*m) Specifies the static friction of the motor, in N*m. Back EMF (V/krpm) Specifies the Back EMF in Volts/thousand rpm required to maintain a velocity. This value is used to determine max operating speed during operation. If this value times the current speed is not greater than the Vbus of the drive, the simulation will not allow for a faster velocity. Max Velocity (RPM) The maximum velocity possible by the motor. Motor Pole Pairs The number of Magnetic Pole Pairs in the motor (on the rotor shaft).

Encoder Parameters

The motor parameters for this block are as follows:

Style Specifies a rotary or linear encoder. Encoder Type Specifies which type of encoder is on the motor (ie, AQuadB, Sin/Cos, SFD, EnDat, BiSS, etc). Encoder Pitch Specifies which type of encoder is on the motor (ie, AQuadB, Sin/Cos, SFD, EnDat, BiSS, etc). Resolution The resolution (encoder counts) that is generated by the feedback every Encoder Pitch (described above). If using a Kollmorgen Drive, this value is automatically populated.

Matlab/Simulink

Simulink Interface

In the block diagram for the Drive/Motor block, note the Output Mux called Motor Shaft (Out).

For determining a custom mechanical structure before an encoder, this Mux contains all of the required parameters to configure a spring body mass system, which allows you to design a block that matches your custom mechanical structures in any machine. This block provides virtual tuning of your servo system using your custom parts. Additionally, can assist in identifying resonances, or other mechanical problems before manufacturing. This is beneficial by allowing revisions to your machine before any resources are wasted.

Notes:

This block assumes a value of Ts has been entered into the Matlab workspace. Ts = 1/SampleRate.

When a model containing the Motor/Drive block is downloaded to a controller, the block is discarded and not saved in the controller firmware. This block is a simulation block only.