Emerson Epsilon Eb Series - User Defined Motors; Overview; Commutation Basics

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User Defined Motors
Overview
This chapter describes how to create user defined motor selections for use with the drive.
Specifically, it includes:
• Commutation Basics
• Motor Wiring
• Motor Feedback Wiring
• Determine Encoder Alignment
• Determine Motor Parameters
• Editing the MOTOR.DDF File
• Configuring the Drive
• Verification and Checkout
Drives can be configured to operate with brushless DC (synchronous permanent magnet)
motors not manufactured by EMERSON Motion Control. This feature is very useful for users
who are retrofitting drives on existing systems or who have special motor requirements.
Commutation Basics
To properly commutate the motor, the drive must know the electrical angle (the angle
between the motor magnetic field and stator coils; R, S and T). At power-up, the drive
determines the starting electrical angle from the U, V and W commutation tracks. After this
is determined, the U, V and W commutation tracks are ignored and the commutation is
entirely based on the A and B incremental channels. The number of U, V and W cycles must
match the number of poles in the motor but they do not have to be aligned with the motor
poles in any particular way.
The U, V and W tracks have a fairly coarse resolution, therefore, on power-up, the
commutation accuracy is limited to ±30 electrical degrees from optimum. When the Z
channel is seen by the drive, the commutation angle is gradually shifted to the optimum
position as defined by the Motor Encoder Marker Angle parameter. This shift is accomplished
in about one second whether the motor is rotating or not.
Tools Required:
• Oscilloscope dual trace 5 Mhz bandwidth minimum.
• AC/DC voltmeter, 20 VDC and 200 VAC minimum.
• Drill motor (reversible) or some means of spinning the motor.
• Coupling method between the drill motor and the test motor.
• 5 VDC power supply to power the motor encoder.
Epsilon Eb and E Series EN Drives Reference
Manual
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