Nidec Leroy-Somer Powerdrive MD Smart, Руководство по интеграции

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GENERAL INFORMATION
Powerdrive MD Smart Integration Guide
5751 en - 2021.10 / e
GENERAL
INFORMA
TION
1.2.2 - Rectifiers
POWERDRIVE MD Smart rectifiers are elements offered on an IP00 chassis. They generate a DC voltage from the voltage of the
three-phase AC power supply network that supplies them. They are AC/DC converters.
The offer includes 2 types of rectifiers:
- Passive rectifier: used with basic power supplies (three-phase network), operating in 2 quadrants.
- Active rectifier: used with installations requiring the reinjection of current into the network in the case of driving loads or energy
generation (operation in 4 quadrants) or to limit the harmonic rate to a low level (THDI ≤ 3%).
Rectifiers can be used as stand-alone devices to generate a common DC bus for several drives with reduced capacity. This is
called a common DC Bus system. This solution is widely used in multi-axis applications such as cranes and travelling gantries or in
industrial production lines. In fact, this makes it possible to facilitate energy exchanges between the various axes, thus generating
energy savings.
1.2.2.1 - Passive rectifiers
The passive rectifiers of the Powerdrive MD Smart designated MD3REC operate in 2 quadrants, that is, the energy can only flow
from the network power supply to the DC Bus (capacitors). In the case of driving loads or load decelerations that are too fast, the
energy produced cannot be discharged, DC Bus overvoltage phenomena may occur. To avoid any risk of unwanted tripping, this
energy must be dissipated in resistors via a braking module (see chapter §1.2.6 ).
Note
The rectifier bridge is composed of switching electronics (thyristors and diode) responsible for the production of harmonics.
These elements are not linear elements, the current conduction only takes place for a short time, at each sine wave peak to
recharge the DC Bus (capacitors).
These harmonics can cause the overheating of transformers, cables, motors, generators and capacitors connected to the same
power supply. If the network is too polluted, the lights and displays of the electronic devices start to flicker, circuit breakers may trip,
computers malfunction and measuring instruments give erroneous values.
The amplitude of the harmonics is linked to the impedance of the network upstream of the rectifier bridge, and to the structure of the
DC Bus downstream of the rectifier bridge The more inductive the mains supply and the motor are, the more these harmonics are
reduced. They only have an impact on the quality of the network for capacities installed in frequency converters of a few hundred
kVA or in the case where these same capacities are greater than a quarter of the total power installed on a site.
Test
Clause
IEC 18000-5-1
Referenced standard
Electrostatic discharge immunity 5.3.3 IEC61000-4-2
Radio frequency field immunity 5.3.3 IEC61000-4-3
Fast transient burst immunity to power terminals
and control terminals
5.3.3 IEC61000-4-5
Common mode radio frequency immunity to
power terminals and control terminals
5.3.3 IEC61000-4-6
Generic immunity standards for the industrial
environment
5.3.3 IEC61000-6-2
Note
A THD harmonic distortion rate of 30% is equivalent to 5% less RMS current on the line.