Sinopak 3-11kV ac drives for water pump
Isolated transformer: supplies phase shift supply for power cells
and reduces the harmonic interference to grid.
Power Cell Cabinet
Controller: The voltage vector PWM control, signals measurement and
controlling with complete electric isolation by the optic fiber
communication between controller and power cells.
Power Cell: The modular designs, easy to production, maintenance
and replacement with each other. I/O Board: The interface of
digital and analog signals, adaptable for the various applications
on site. HMI: LCD display in multiple-language, easy to operation,
parameter setting, status display, fault recording, etc.
Manual / Automatic Bypass Cabinet (Optional)
To ensure the continuous production in case that the VFD is fault
or stopped, the bypass cabinet allows the motor to be driven by the
Master-Slave Drive Control System (Optional)
It is used for multi-drive system in master-slave mode to keep the
speed and torque balance between all drives (motors), which are
synchronously controlled by the optic-fiber communication.
Grid-Connected Synchronous Switching System (Optional)
It is composed of the switch cabinets, a reactor cabinet and a
sync-controller cabinet. The whole switching system is controlled
synchronously by a sync-controller to ensure that when the VFD’s
output voltage keep the phase-sequence and voltage value same as
the grid system, the motor can be driven at the industrial
frequency by switching into the grid system from the VFD.
Sinopak HVF has a number of power cells connected in series, the
independent phase-shift power is supplied to each power cell by the
isolated transformer. Changing the power cells number in each phase
you can get different output voltage conveniently without the
limitation for the components’ withstand voltage. For example, the
6kV VFD has 5 cells in each phase, the rated voltage of each power
cell is 690V, the phase voltage is 3460V (the line voltage is 6kV);
Power Cell Topology
The power cell adopts AC-DC-AC mode, it is equal to a low voltage
voltage-source inverter with three-phase input and single phase
output. All power cells are same electrical and mechanical
features, thus very easy to maintenance and replacement.
The internal structure of the power unit is shown in the figure
above. The power input ends of R, S, and T are connected to the
three-phase low voltage output ends of the secondary coil of a
transformer. The three-phase diode full wave rectifier charges the
DC link capacitor. The capacitor voltage is supplied to the
single-phase H-bridge inverter circuit composed by IGBT.
Each inverter unit outputs the PWM sine wave. The multiple
technologies are adopted in units connected in series. That is to
say, all amplitudes and frequencies of the output voltage of n
units on each phase are identical, but there exists a phase
difference of a certain angle (with a difference of 1/n switching
period). Therefore, the phase voltage waveform generated by n units
connected in series has (2n + 1) levels. As a result, the harmonic
content in the waveform is significantly reduced and the waveform
is almost similar to a perfect sine wave. The figure below shows
the overlap waveform generated by 3 units connected in series and
the load voltage and current waveform actually measured.
By adopting the improved and perfected flux optimization and
control with space vector PWM technology of the latest generation
and in combination of state-of-the-art control theory, the control
software is developed by a Germany R & D team on its own. The
control precision of the dynamic rotational speed is lower than ±
2% of the rated speed. The torque step response time < 10 ms.
The output frequency resolution is up to 0.01 Hz.
High reliability design
High reliability and long service life
Reliability and stability shall be taken as the principle when
selecting the models of core components. It is recommended that
IGBT, rectifier bridge, driver module, capacitor, and optical fiber
of internationally famous brands should be adopted. Sufficient
safety surplus should be left when selecting the capacity to
enhance overload capacity of the products and guarantee their
reliability and long service life.
In terms of structure design, we absorb the leading design idea
from the internationally famous brand companies like ABB, Siemens,
and Robicon and adopt the mature and stable structure with multiple
units connected in series. Also, we use a module design and make
the standard unit have the auto bypass function to enhance the
operation reliability of the products and thus significantly reduce
the possibility of failure shutdown
The designed service life is 20 years, designed MTBF is longer than
100 thousand hours, and designed MTTR is shorter than 10 minutes.
Good heat dissipation and ventilation effect can be guaranteed as
internationally famous brand cooling fans with long service life
are installed on the top of the transformer cabinet, the inverter
unit cabinet, and the control cabinet. The MTBF of the air cooling
system is longer than that of the devices.
Infallible power supplied by the control power supply
The power for the system is supplied by a power supply controlled
by double loops with standard configuration. (1-way internal loop
of 220 VAC and 1-way external loop of 220 VAC). The internal
control power supply is taken from an auxiliary secondary line
winding of the input side isolation transformer. The control power
supply will not lose power as long as the high voltage main power
supply is active. When the high voltage main power supply lose
power, the external power supply (220VAC) will maintain a supply.
The optional external control power supply (220 VDC or 110 VDC)
input mode is specially designed for the direct power supply
measuring and controlling system in a high-voltage power
distribution room to obtain a stable control power supply from the
DC system in a convenient way.
An optional UPS is available to obtain a more stable redundant
Optical fiber communication is adopted inside the VFD to realize
the complete optical isolation
and a good anti-interference performance.
Automatic current-limiting operation function
Sinopak HVF MVVFD adopts the space vector and PWM control
technology of the latest generation to realize the automatic torque
limitation function. When the situation of abnormal load such as
short-time high overload or short-time mechanical jamming occurs
abruptly, Sinopak HVF MVVFD can automatically reduce the operating
frequency, limit the output power, torque, and current, and
maintain its operation to avoid over-current trip. After this
phenomenon of abnormal load disappears in a short time, the VFD
will return to normal operating frequency.
Power unit bypass operation
The entire Sinopak HVF series feature hardware bypass operation for
power units. When a power unit is faulty, this faulty power unit
can be automatically switched to the bypass through the automatic
bypass technology and the output three-phase voltage is
automatically balanced for continuous operation of the VFD. At most
3-stage bypass function is offered. After the unit is switched to
the bypass mode, the output can be adaptively regulated according
to bypass stages and the current load to maintain a higher output
▲ A contactor is taken as the hardware bypass component for
excellent anti-interference performance and greater security.
▲ The bypass and the inverter circuit work independently and thus
have higher stability.
Perfect and reliable structure design
Electromagnetic shielding has been performed on the cabinet and the
electromagnetic compatibility (EMC) meets stringent IEC1000-4 and
IEC1800-3 requirements. The integrated design includes the dry-type
transformer (H class insulation) with high reliability. The
temperature of the iron core and windings of a phase-shifting
transformer can be monitored. A threshold switch is designed on the
transformer cabinet to ensure that the system will generate an
alarm if the cabinet door is opened when the transformer is in
operation. The heating equipment preventing condensation due to low
temperature can be adopted to ensure that the transformer can
operates in a cold and humid environment for a long time.
Surge absorption capacity for power protection
The entire Sinopak HVF serial products have the surge absorption
capacity for power protection which enables them to fully absorb
the peak current for successful power-on at once. The surge
absorption capacity for power protection of Sinopak HVF includes
the following two parts:
Anti-surge circuit for a unit
▲ Anti-surge measure for a unit
The input voltage of a power unit, through a fuse, enters a
three-phase bridge rectifier for rectification, and then it is
filtered by an electrolytic capacitor to become a direct current.
To prevent the surge current upon power-on, a contactor and a
resistor should be put in parallel, and then they should be
connected in the middle of a three-phase bridge rectifier and a
filter electrolytic capacitor in series. As a result, the
electrolytic capacitor will be charged through a power resistor
upon power-on. After the charging is finished, the contactor is
▲ Anti-surge measure for a system
The main circuit of a phase-shifting transformer is equipped with
anti-surge resistors upon power-on and a vacuum contactor, which
can effectively reduce the excitation inrush current and the
electrolytic capacitor charging current at the moment of switching
on, for a successful switch-on operation at once.
▲ High voltage surge arrester for surge protection
The input terminal of a high voltage power supply is equipped with
a surge arrester, which can absorb a lightning surge and the surge
formed by the switching overvoltage in the power grid.
Start with full torque at low speed
Benefiting from the leading "dynamic PWM" software, Sinopak HVF
MVVFD can operate stably at an extremely low frequency
(approximately 0.1 Hz) with the widest range of speed regulation.
The starting torque of the VFD is adjustable. When starting a
overloaded device, like a belt conveyor, a roller mill, or a
draught fan suffering from jamming due to a seriously corroded
bearing shell, the VFD can output an extremely large starting
torque at an extremely low operating frequency (approximately 0.1
Hz) to ensure a normal start of a load.
Sinopak HVF MVVFD is a high-performance VFD which is not only
suitable for variable torque loads, but also suitable for constant
Starting a motor inversely rotating at a low speed
Benefiting from its excellent features, Sinopak HVF MVVFD has the
function of "starting a motor inversely rotating at a low speed".
It adopts a technology equivalent to the DC braking (DC brake) when
starting a motor inversely rotating at a low speed. First, it slows
the speed of a motor inversely rotating at a low speed down to
zero, and then make the motor run from zero speed. The function of
"starting a motor rotating inversely at a low speed" allows the
MVVFD to start a motor rotating inversely in a safety mode without
Restart with speed tracking (Flying start)
Sinopak HVF MVVFD adopts the unique "slip current control
algorithm" to automatically search and recognize the motor rotating
speed. It starts the rotary electric motor at current speed rather
than the zero speed for a safe startup at a low current. Therefore,
it reduces the impact on the power grid and weakens the influence
on production when an immediate outage occurs.
Excellent input side features
For 6 kV devices: 30/36 impulse input.
For 10 kV devices: 48/54 impulse input.
The grid-side harmonic is low. No need to install the noise filter.
The input harmonic content can meet the requirements of IEEE
519-1992 and GB/T14549-2002.
The power factor exceeds 0.97 at rated load in the range of normal
The blue curve and yellow curve in the diagram refers to the input
current curve and the input voltage curve respectively. Both
waveforms are close to the sine wave, with negligible harmonic
Excellent output features
The Sinopak HVF MVVFD can output excellent multi-level PWM sine
waves. A 6 kV MVVFD can output an 11- or 13-level phase voltage,
and a 21- or 25-level line voltage; a 10 kV MVVFD can output a 17-
or 19-level phase voltage, and 33- or 37-level line voltage. It has
a small dt/dv value, and the output voltage and current waves are
near perfect sine waves. It has no special requirements to the
driven motor and can drive motors made in China.
Common power cables can be adopted as input and output cables. The
output cable stretches as long as 1,500 m (inform Cumark in advance
if you need a longer cable). The Sinopak HVF MVVFD can operate
stably with small output voltage and current harmonics, small motor
torque ripple, and low noises.
Complete fault handling functions
With its complete fault diagnosis, location, and handling
functions, the Sinopak HVF MVVFD categorizes and handles faults
based on severities, outputs the fault and content in real time,
and record the fault in the log.
The Sinopak HVF MVVFD also has a series of complete protection
functions for MVVFD overheat, input overvoltage, input
undervoltage, output overcurrent, motor overload, output grounding,
output short-circuiting, equipment overload, power unit fault,
cooling fan fault, and interlocking of doors to the high voltage
switchgear. Some fault can intertrip the high voltage switchgear on
the input side.
Powerful adaptative feature to the voltage fluctuation of power grid
Sinopak HVF MVVFD can operate at full load when the power grid
voltage ranges from -20% to 15%
Sinopak HVF MVVFD can continue to operate at a derated load with
decrease of the power grid voltage by 35%
Power loss ride-through and power failure recovery features
Sinopak HVF MVVFD can maintain a normal operation within 10 cycles
after immediate power outage. A longer power outage duration is
allowed when Sinopak HVF MVVFD operates under light load.
When VFD loses power for a period longer than 10 cycles, it will
automatically operate at a derated load. The VFD will shut down
when the power outage duration exceeds 10 seconds.
When the power is transmitted again by the power grid, it is
recommended that the Sinopak HVF MVVFD should be re-started after
the automatic speed tracking is set based on the requirements.
Reliable redundancy control feature
The core control part of Sinopak HVF MVVFD is designed by two
control systems adopting PLC and touchscreen based on the DSP
control board, which is a dual redundancy control mode. The PLC
system is taken as the external interface, realizing a transition
from the external control port to the internal DSP control board.
The external port is completely isolated from the internal control
board. This not only significantly enhances the reliability and
anti-interference ability of the system to avoid interference on
the control part of the VFD from an external system, but also is
conducive to the upgrade and maintenance of the system and addition
of the monitoring function. The design is more reliable when
compared with the design of adopting only a single chip control
board adopted by most similar manufactures in China.
Safe resonance avoidance
Sinopak HVF MVVFD allows users to configure three sets of resonance
frequency hopping points to effectively avoid mechanical resonance
of the electromechanical system and thus to ensure the safe and
reliable operation of the drive system.
Automatic flux optimization
Sinopak HVF MVVFD adopts the exclusive flux optimization technology
which enables real-time monitoring and flux optimization on the
entire speed regulation system including the motors, and thus
increases the system efficiency by 1% to 10% and save more energy
than a similar VFD does.
The automatic flux optimization also facilitates reduced operating
current of the motor and improved stability of the device. Current
motors are made based on the power frequency design patterns. When
some motors are running at a variable frequency, the best magnetic
intensity rather than rated magnetic intensity may occur at a
particular frequency (especially within the medium or low frequency
range), which may cause large operating current and unstable
operation if the traditional vector control strategy is adopted. In
this case, Sinopak HVF MVVFD will enable automatic flux
optimization in combination of the space vector PWM control
algorithm to adjust the motor flux to the specification value of
the motor, reduce the operating current of the motor and improve
the stability of the system.
Large capacity design
The designed power of 10 kV is 20,000 kW, 6 kV 12,000 kW
respectively. Tens of synchronous/asynchronous motors with high
power above 5,000 kW have enjoyed success in many applications.