The frequency changer is in the movement control
system power transformer. The now movement control system
contains the many kinds of disciplines the area of technology, the
always development tendency is: Actuation exchange, power
transformer high frequency, control digitization, intellectualization
and network. Therefore, the frequency changer took the system
the important power transformation part, provides the controllable
high performance live pressure frequency conversion the alternating
current supply to obtain the swift and violent development.
Along with new electric power electronic device and high
performance microprocessor application as well as control technology
development, frequency changer performance price compared to more and
more high, the volume is more and more small, but the factory still in
unceasingly enhanced the reliability to realize the frequency changer
further small 轻量, the high performance and multi-purpose as well
as does not have the environmental damage to make the new effort.
The frequency changer performance fit and unfit quality, one
need to look at its output alternating voltage the overtone to the
electrical machinery the influence; Two must look to the
electrical network overtone pollution and the power input factor;
How three has to look at itself energy loss (namely efficiency).
Here only - is straight take the quantity big surface broad
junction - hands over the frequency changer as an example, elaborates
its development tendency:
The main circuit power on-off element from shuts off, the
modulation, the integration, the intellectualization; The
turn-on frequency unceasingly enhances, the switch loses further
reduces.
Frequency changer main circuit topology aspect. The
frequency changer net side converter often uses 6 pulses converters to
the low pressure low-power installment, but presses the large capacity
installment to the center to use above the multiple 12 pulses the
converter. The load side converter often uses two levels to the
low pressure low-power installment the bridge type inversions, but
presses the large capacity installment to the center to use the multi-
levels inversion. Regarding four quadrants movements rotation,
for realizes the frequency changer regeneration energy and saves the
energy to the electrical network back coupling, the net side converter
should be the reversible converter, simultaneously appeared the power
to be possible the two-way flow double PWM frequency changer,
performed to the net side converter suitably to control may enable the
input current to approach the sine wave, reduced to the electrical
network environmental damage.
The pulse-duration modulation live pressure frequency changer
control method may use the sine wave pulse-duration modulation
control, the elimination assigns the number of times overtone the PWM
control, the electric current follow-up control, the voltage space
vector control (flux linkage follow-up control).
The motor frequency conversion adjustment control method
progress mainly manifests in develops and develops the non- velocity
generator by the scalar control to the high dynamic performance vector
control and the direct torque control the vector control and the
direct torque control system aspect.
The microprocessor progress causes the numerical control into
modern controller the development direction. The movement
control system is the fast system, specially the motor high
performance control needs to save the many kinds of data and the fast
real-time processing massive information. In the last few years,
the overseas each big company in abundance promotes take DSP (digital
signal processor) as the foundation essence, matches periphery
function electric circuit which needs by the electrical machinery
control, integrates is called the DSP monolithic electrical machinery
controller in the sole chip, the price greatly reduces, the volume
reduces, structure compact, the use is convenient, reliable
enhancement. DSP and the ordinary monolithic integrated circuit
compare, the processing numeral operation ability strengthens 10 ~ 15
times, may guarantee the system to have the more superior control
performance. The numerical control causes the hardware to
simplify, the flexible control algorithm enable the control to have
the very big flexibility, may realize the plurality of controls rule,
causes the modern control theory to apply into the reality in the
movement control system, easy carries on the data transmission with
the upper formation system connection, is advantageous for the
breakdown diagnosis, strengthens the protection and the surveillance
function, enable the system intellectualization (for example some
frequency changers to have from adjustment function).
The exchange synchronous motor has become the exchange to be
possible to adjust in the rotation a nova, specially the permanent
magnetism synchronous motor, the electrical machinery obtains not
brushes the structure, the power factor high, efficiency also high,
the rotor rotational speed is strict and supply frequency maintenance
synchronization. The synchronous machine frequency conversion
velocity modulation system has him to control the frequency conversion
and the automatic control frequency conversion two big kinds,
automatic control frequency conversion synchronous machine in
principle and direct current machine extremely similar, has
substituted for the direct current machine mechanical commutator with
the electric power electron converter, when uses hands over - is
straight - hands over the live pressure frequency changer is called
"the direct current non- commutator machine" or called "not brushes
the direct current motor". The traditional automatic control
frequency conversion synch ronizer velocity modulation system has the
rotor position transducer, right now develops the non- rotor position
transducer the system. Synchronous machine he controls the
frequency conversion format also to be possible to use the vector
control, it is simpler than according to the rotor magnetic field
direction detection vector control the asynchronous machine. The Chinese mechanical and electrical enterprise network
supplies the manuscript
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