Relation Between Maximum Voltage Spec and Power Amplifier (Drive) Voltage Spec Hardware: Motion Control>>Power Drives
Problem: I own a motor that has specifications for a maximum allowable voltage that is considerably less than the rating for all of the corresponding National Instruments drives. Does this mean I need another amplifier? Solution: No. The voltage spec for motors means that if you apply more than that amount of voltage in a continuous manner (with a battery for example) to the motor for an extended amount of time, you will probably damage it. This damage, however, is related to the continuous current flowing through the motor coils, as the motor will try to sink as much current as possible if the current that it receives is not controlled. National Instruments drives, do not continuously output a voltage to the motor, but rather a current. This is achieved by constantly sending a Pulse Width Modulated (PWM) signal of 0-24 volts (for the MID 7602/4) or 0-48 volts (for the MID 7652/4). By varying the duty cycle of this PWM output, it changes the Root Mean Squared (RMS) value of the voltage, and yields the amount of current desired. Motors generally specify the amount of continuous and peak current that they can handle. National Instruments drives can set the limit for the current that they generate by means of their front panel dip switches. As long as the current spec of the motor is not lower than what National Instruments drives generate, the motor should be fine regardless of the voltage rating. Related Links: National Instruments Motion Control Support Homepage Attachments:
Report Date: 03/16/2004 Last Updated: 04/30/2004 Document ID: 37FC7745 |
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