Applied Motion 3540MO - Manual (Page 3)

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Choosing a Power Supply
Voltage
Chopper drives work by switching the voltage to the motor terminals on and off
while monitoring current to achieve a precise level of phase current. To do this
efficiently and silently, you’ll want to have a power supply with a voltage rating at
least five times that of the motor. Depending on how fast you want to run the motor,
you may need even more voltage. More is better, the only upper limit being the
maximum voltage rating of the drive itself: 42 volts (including ripple).
If you choose an unregulated power supply, do not exceed 30 volts DC. This is
because unregulated supplies are rated at full load current. At lesser loads, like
when the motor is not moving, the actual voltage can be up to 1.4 times the voltage
listed on the power supply label.
Current
The maximum supply current you will need is the sum of the two phase currents.
However, you will generally need a lot less than that, depending on the motor type,
voltage, speed and load conditions. That's because the 3540 MO uses switching
amplifiers, converting a high voltage and low current into lower voltage and higher
current. The more the power supply voltage exceeds the motor voltage, the less
current you’ll need from the power supply.
We recommend the following selection procedure:
1. If you plan to use only a few drives, get a power supply with at least twice the
rated phase current of the motor.
2. If you are designing for mass production and must minimize cost, get one
power supply with more than twice the rated current of the motor. Install the motor
in the application and monitor the current coming out of the power supply and into
the drive at various motor loads. This will tell you how much current you really
need so you can design in a lower cost power supply.
If you plan to use a regulated power supply you may encounter a problem with
current foldback. When you first power up your drive, the full current of both motor
phases will be drawn for a few milliseconds while the stator field is being
established. After that the amplifiers start chopping and much less current is drawn
from the power supply. If your power supply thinks this initial surge is a short
circuit it may “foldback” to a lower voltage. With many foldback schemes the
voltage returns to normal only after the first motor step and is fine thereafter. In that
sense, unregulated power supplies are better. They are also less expensive.
The PS430 from Applied Motion Products is a good supply to use with
the 3540 MO.
Table Of Contents
Introduction 4
Features 4
Block Diagram 4
Getting Started 5
Modes of Operation 6
Joystick Mode 6,7
Oscillator Mode 8,9,10
Speed Control from a 0 to 5 Volt Analog Signal 9,10
Tach Output 11
Connecting Digital Inputs and Limit Switches 11,12
Connecting the Motor 12,13
Microstepping 14
Setting Phase Current 14
Current Setting Table 15
Idle Current Reduction 16
Connecting the Power Supply 16
Mounting the Drive 17
Recommended Motors 17
Choosing a Power Supply 18
Technical Specifications 19
Mechanical Outline back cover