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ES9000A/S General MV VFD

3~11 kV 250kW-20MW/315-25000kVA
Sinopak's ES9000 MVVFD is available in either an integrated structure or a split type structure based on capacity, also outdoor containerized structure based on customer's demand.


  • Integrated structure
  • Split structure
  • Containerized MVVFD
  • Power cell cabinet
  • Transformer cabinet
  • Control cabinet

Isolated transformer: this transformer supplies the phase shift supply for power cells and reduces harmonic interference in the grid.

Controller: The voltage vector PWM control signals measurement and control with a complete electric isolation through a fiber optic communication between the controller and power cells.
Power Cell: These cells feature a modular design, are easy to produce, maintain and replace.
I/O Board: The board utilizes an interface of digital and analog signals, making it adaptable to various applications on site.
HMI: LCD displays multiple languages, and is easy to operate, set parameters, display the status, and record any faults.

Manual/Automatic Bypass Cabinet (Optional)
To ensure the continuous production in the event the VFD has a fault or stops, the bypass cabinet allows the motor to be driven by the grid system.

Master/Slave Drive Control System (Optional)
This is used for multi-drive systems, as master/slave mode retains the speed and toque balance between all drives (motors), which are themselves synchronously controlled using fiber-optic communication.

Grid Connected Synchronous Switching System (Optional)
The grid connected synchronous switching system is comprised of the switch cabinets, a reactor cabinet and a sync controller cabinet. The entire switching system is synchronously controlled using a sync controller in order to ensure that when the VFD's output voltage keeps the phase sequence and voltage values the same as the grid system, the motor can be driven in an industrial frequency by switching from the VFD to the grid system.


Topology of System
Take  6kV  as an example

  • Topology of System 6kV
  • Voltage Overlapping Method
  • Power Cell Topology

ES9000 MV VFD has numerous power cells connected in the series. The independent phase shift power is supplied to each power cell through the isolate transformer. Change the amount of power cells in each phase, and you can get a different output voltage without limiting the component's ability to withstand various voltages. For example, the 6kV VFD has 5 cells in each phase, and the rated voltage of each power cell is 690V. This means the phase voltage is 3450V (the line voltage is 6kV).

The power cell uses an AC-DC-AC mode, which is equal to a low voltage source inverter with three phase output and single phase output. All power cells feature the same electrical and mechanical features, making them easy to maintain and replace.

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 on a transformer. The three phase diode full wave rectifier charges the DC link capacitor. The capacitor voltage is then supplied to the single phase H-bridge inverter circuit composed of the IGBT.

Each inverter unit outputs the PWN sine wave. Multiple technologies are used in the units, and each is connected to form a series. In other words, all amplitudes and frequencies of the output voltage of the N units in each phase are identical, but there is a phase difference at certain angles (with a difference of 1/n switch period). Therefore, the phase voltage waveform generated by the n units connected in the series has (2n 1) levels. As a result, the harmonic content in the wave form is significantly reduced, and the waveform is almost similar to a perfect sinusoid wave. The figure below shows the overlap waveform generated by 3 units connected in a series, where the load voltage current waveform have actually been measured.


By using an improved and perfected flux optimization, the latest control with a space vector PWM technology, and a combination of state of the art control theory, the control team was developed by a German R&D team. The control precision of the dynamic rotational speed is lower than ± 2% of the rated speed. The torque step response time is ˂ 10 ms. The output frequency resolution reaches up to 0.01 Hz.

1. High reliability: The ES9000 high-voltage variable frequency drive utilizes the most advanced thermal reliability design technology, repeat design technology, automatic bypass technology, an integrated design technology and other design concepts. It is made of high quality raw materials, and goes through an extensive production process, complete aging testing test, and strict quality inspection processes to ensure that each product has the reliability that customers expect from us. We invested more than 20 million dollars in 2012 to build the first 2500kW back to back test platform in China, which is capable of conducting 44 pre delivery tests, including full load, overload, and voltage fluctuation tests, all to ensure long term stable operation.

2. Advanced Control Performance: The ES9000 high voltage variable frequency drive uses an SPWM space vector control technology as well as flux optimization control technology. Compared to similar products, it is more user friendly, more advanced, and more energy efficient.

3. Comprehensive Functions: This machine has numerous advanced functions, including energy feedback, flying start, current limit, synchronous undisturbed switching, master/slave control, and more. With a high adaptability rate, it can drive multiple load types.

4. Surge absorption capacity for power protection
5. Start with full torque at a low speed
6. Starting motor inversely rotating at a low speed
7. Restart with speed tracking (flying start)
8. Input side features
9. Output features
10. Complete fault handling functions
11. Power adaptive ability for voltage fluctuation on the grid
12. Power loss ride through and power failure recovery
13. Reliable repeat control feature
14. Safe resonance avoidance
15. Automatic flux optimization
16. Large capacity design

Technical Parameters

Medium voltage input Voltage range 3kV, 4.16kV, 6kV, 6.6kV, 10kV, 11kV (-20%~ 15%)
Frequency range 50/60 Hz±10%
Medium voltage output Output voltage 0~Rated voltage
Output frequency and accuracy 0~50/60 Hz, 0.01 Hz
Output waveform Multilevel PWM sin wave, total harmonic distortion (THD) < 4%
Performance Efficiency Inversion efficiency at an rated load > 98.5%, overall efficiency (including the transformer) > 97%
Power factor Power factor (within the range of speed regulation) > 0.95, power factor (at a rated load) > 0.97
Overload capacity 110%: long-term stable operation, 120%: 1 minute, 150%: 2 seconds, and 160%: immediate protection
Allowable outage duration 200 ms (and longer under light load)
Mean time between failures > 100,000 hours
Control Control mode F lux optimization and control with space vector PWM
Acceleration/deceleration time 1 to 3 ,600 seconds
Switching quantity input/output 11-way/10-way
Analog input 4-way (optional: 0 to 5 V, 4 to 20 mA)
Analog output 3-way (optional: 0 to 10 V, 4 to 20 mA )
Communications RS485 interface, ModBus RTU, Profibus DP (optional), Industry Ethernet Protocol (optional)
Control power supply Single-phase 220 V AC, 5kVA
Excitation control ( dedicated for the synchronous motor) Control mode Automatic excitation control, manual excitation control, multi-stage speed excitation control, and external excitation control for the M VVFD
Environment Operating environment Operating in indoor environment without explosive or corrosive gases, conductive dust, or oil fog
Operating ambient temperature 0 ℃ ~ 4 5 ℃
Storage and transportation temperature -40 ℃ ~ 70 ℃
Ambient humidity < 90% (No condensation)
Operating altitude Derating required for an altitude greater than 1000 meters
Others Protection function Overcurrent, overload, short circuit, three phase current unbalance, immediate electric outage, input/output phase loss, overvoltage, undervoltage, body overheat, transformer overheat, shutdown due to external fault, and power unit auto bypass
Cooling mode Forced-air cooling
User interface An 10-inch Human Machine Interface
Protection grade: Indoor IP31, Outdoor IP54


  • Used in blast furnace fan
  • Used in boiler
  • Used in compressor
  • Used in condensation pump
  • Used in kiln ID fan
  • Used in river intake pump

Taking a main sintering exhaust fan in an iron and steel plant as an example:
The ES9000 high voltage variable frequency drive is widely used in domestic, large scale steel and iron plants due to its outstanding reliability. A few customers include the China Railway Engineering Equipment Group (double main exhaust fan variable frequency drive), No. 3 Sintering Plant project from Kunming Iron and Holding (double main exhaust fan variable frequency drive), Fujian Sangang Group (main exhaust variable frequency drive) and more. They have come to us knowing they receive excellent economic and social benefits with the use of our machine.

Taking a belt master/slave drive system in the mining industry as an example:
The belt drive system is complex, in that it needs to achieve the rotation speed balance between the front and rear drive motors, torque balance, current balance, downline belt power feedback and other factors. This is one of the most difficult technologies to master in high voltage variable frequency drives. Ours was used for the first time in 2014 in a 5km belt conveyor driving system for the Yangquan Coal Industry Group. After more than 2 years, they are still using our product.

Synchronous undisturbed switching system: In remote areas, self-built small diesel power generation systems are generally of a very low power capacity. In order to reduce investment put into it, a synchronous undisturbed switching system is required to start the motor. This system can convert the variable frequency mode to power frequency modes in the same phase and frequency. This results in no detrimental impact to the power supply.

ES9000 high voltage variable frequency drives are widely used in boiler auxiliaries, constant pressure water supply in water systems, internal mixers, high temperature fans and other industrial fields.