Applied Motion BLuDC4-Si - Manual (Page 19)

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BLuDC-Si Hardware manual BLuDC-Si Hardware manual BLuDC-Si Hardware manual BLuDC-Si Hardware manual BLuDC-Si Hardware manual
motor. To get a rough estimate of how much voltage you need, multiply the voltage constant of the
motor (Ke) by the maximum speed required for your application. For example, if you want to
operate the A0100-103-3 at 4000 rpm, you'll need V = Ke * rpm = (4.04V/krpm)(4 krpm) = 16
volts. To produce any real torque at that speed, add 50%, for a total of 24 V.
Always check the "no load" voltage of the power supply before using it with the drive, to be sure
that it does not exceed 52 VDC.
Current
The maximum supply current you could ever need is three times the motor current.
However, you will generally need a lot less than that, depending on the motor type, voltage, speed
and load conditions. That's because the BLU servo uses a switching amplifier, 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. A motor running
from a 48 volt supply can be expected to draw only half the supply current that it would with a 24
volt supply. Furthermore, the servo loop only commands the amplifier to provide as much current
as load conditions require.
We recommend the following selection procedure:
1. If you plan to use only a few drives, get a power supply with at least 3X the rated
continuous 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 regeneration. If you
rapidly decelerate a load from a high speed, much of the kinetic energy of that load is transferred
back to the power supply. This can trip the overvoltage protection of a switching power supply,
causing it to shut down. Unregulated power supplies are better because they generally do not have
overvoltage protection and have large capacitors for storing energy coming back from the drive.
They are also less expensive.