David Kerzel via EV wrote:
Most of these can run off DC either from DC input terminals or Just run the
DC in the AC inputs but derate as if it was a single phase input drive.
Input voltage should be nominal RMS AC voltage to peak AC voltage.
The drive is a volts/hertz or vector type, and they rely on a 3 phase motor
load for feedback. If they can make single phase power it would be pure
luck.
David Kerzel
Modular EV Powe LLC
-----Original Message-----
From: EV <[email protected]> On Behalf Of John Lussmyer via EV
Sent: Wednesday, June 19, 2019 11:59 AM
To: Electric Vehicle Discussion List <[email protected]>
Cc: John Lussmyer <[email protected]>
Subject: [EVDL] Possibly use as a Pack->AC inverter?
This is nominally a 3 phase VFD. Powered by single-phase AC.
Seems like it must be converting to DC first anyway, so may allow DC input.
It also can drive a single-phase AC motor.
Anyone know if this is a likely possibility?
It's possible. It depends on the circuit topology it uses, what the
programmers expected for a load, and what *you* will connect to it as a
load.
There are two basic topologies:
1. The input stage is a simple rectifier. It rectifies the incoming AC
into DC to produce an unregulated voltage of about 230vac x 1.4 =
320vdc. This powers a DC/AC inverter for the load. This type may not
work on DC, unless you have close to 320vdc as your input voltage.
2. The input stage is a PFC boost converter. It boosts the rectifier
input voltage from whatever it is to a regulated 350 vdc regardless of
the input voltage. This type can often work with a wide range of DC
input voltages as well as AC.
What the programmers expected for a load:
Motors are a complex inductive load. Most VFDs assume an induction motor
as their load. They use motor inductance as part of their circuit (just
as DC motor controllers use a series DC motor's field as part of their
circuit). So it may not work well with a non-motor load.
Older/cheaper VFDs have a way to command a speed, and blindly produce an
AC voltage and frequency proportional to the desired speed. This works
for simple constant-load applications.
Many modern/more expensive VFDs try to "tune" themselves to the motor's
characteristics. This can provide better torque/speed control, and
improve efficiency over a wider range of loads. But this type may not be
"happy" with loads that it isn't programmed to detect.
Bottom line: You'll just have to try it. It Chinese... You feel lucky,
Yank? :-)
--
In software development, there are two kinds of error: Conceptual
errors, implementation errors, and off-by-one errors. (anonymous)
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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