The reliable question passes through in the system structural
design, the primary device total and the quality (including tube core
flaw), the computer technology and software, the quality control and
the debugging maintenance entire process. It is the industry
technical level and the enterprise quality synthesis manifests.
The high-pressured frequency changer product dissolved has
gathered the reliability design idea and the zero flaw quality control
method, it should carry out from the overall plan, the design, the
programming, the selection, the manufacture, the test and the use
maintenance each link. The computer and the network technology
development and the application enable the reliable technology not to
have to the traditional content, has developed to a brand-new stage,
has developed a series of based on the software technology new method,
and causes the system realization breakdown from the diagnosis, from
the repair, the long-distance range diagnosis and the maintenance
consultation.
Under from host return route aspect and so on topology, power
primary device, reliable redundancy and debugging maintenance carries
on the discussion.
1 host return route topology
In the high-pressured frequency changer, the main return
route topology has the many kinds of different plans. But in the
practical application, is two kind of plans which at present quite are
many:
(1) uses the unit which IGBT constitutes to connect
the multi- levels PWM voltage frequency changer;
(2) uses IGCT/SGCT to constitute 中?the
clamp three levels electricity 压型 frequency changer.
In this course fourth lecture, once has made the introduction to
these two kind of plans principle and the characteristic, presently
again performs from the reliable angle to explain and the comparison.
In makes before the comparison, first gives a simple explanation
to three levels high pressures frequency changer host return route
practical line. Connects the multi- levels frequency changer
regarding the unit, because before had more articles to discuss, here
no longer duplicates.
Now performs take 12 pulse waves 中?clamps three levels
frequency changers host return route as the example to explain (see
Figure 1). By chart obviously, after six rectification bridges,
meets anti- has the high voltage surge to accommodate the absorbing
circuit. In the direct current generatrix, the string has two
IGCT to take the pre- charge limits flows and the fuse; Two
anti- altogether molds voltages reactor; Two sets by clutch flow
the reactor, the diode and the resistance constitution di/dt killer.
Has 中?the clamping diode in the inversion power
component side joint and presses the resistance and so on. Still
needs in the out-port establishes the L-C filter.
As a result of the IGCT component pressure resistance limit, certain models three levels frequency changers until now
still 无输?the voltage 6,000 volts specifications products, for
the convenience in order to, presently make the reliable comparison
with the output voltage 4,160 volts specifications products.
By table 1 obviously, connects in the multi- levels frequency
changer in the unit, the inversion power component quantity are more,
but the host return route is a low pressure, the major
component may make the redundancy design; Uses has applied many
year IGBT component in the low pressure frequency changer; The gate actuation electric circuit is simple;
Output overtone small, dv/dt small, anti- altogether mold
voltage performance better, is friendly to the electric motor.
Selects high voltage IGBT, the reduced power unit quantity,
enhances the system efficiency, is the next step of improvement
direction. 中?in clamp three levels high pressures
frequency changer rectification and contravariant return route power
component less, the system efficiency is higher; But in
the host return route the high efficiency attachment component are
more, in the return route the high-pressured power part redundancy at
present still did not have the solution; Gate actuation electric
current big, actuates the line to be complex; The output
overtone and dv/dt are bigger, must establish the L-C filter.
This plan comparatively is suitable to making the AFE way, the
coordinate special-purpose electric motor high voltage converter
system, like mill, hoist and so on. Along with the technical
development and the IGCT component pressure resistance enhancement,
the gate actuate the line the simplification, this technology has the
certain prospects for development.
2 powers components performance
In the high-pressured frequency changer, at present uses
the quite many powers component when counts IGBT and IGCT, now
tabulates to their performance makes a contrast (to see Table 2).
IGBT because it shuts off loses slightly, turn-on frequency
high, actuation power low, the gate actuation electric circuit simple
and the protection is easy and so on the characteristic, had the
mature application in the low pressure frequency changer;
Connects in the multi- levels high pressure frequency changer in
the unit also to demonstrate its usability and the efficiency.
Uses pressure resistance higher IGBT, further will enhance the
system the performance. IGCT is one kind of new high efficiency
component, its switch fast, clears the ability strongly, the storage
time is short, the switch loses lowly. In order to reduce the
lead inductance, its core must the AND gate actuation electric circuit
integration installment, the whole replacement. After IGCT
component pressure resistance rank enhancement, it will be constitutes
the high efficiency and really the high efficiency high pressure
frequency changer optimal power component. |
