high voltage vfd Core operating principle

The input stage employs a dry-type rectifier transformer with precisely phase-shifted angles to achieve 36-pulse multi-rectification, effectively eliminating grid-side harmonics below the 35th order.
Power cells, fed by secondary transformer windings, consist of four H-bridge cells per phase connected in series. These cells synthesize a high-quality sinusoidal output voltage through phase-shifted carrier PWM modulation, significantly suppressing motor-side harmonics.
A fully digital control system enables precise sensorless vector control and operational management, complemented by a high-efficiency water-cooling system that ensures stable thermal dissipation under high-power conditions.

Primary System Diagram

product-1525-977

Product Features

The RNHV 3000 integrates high voltage VFD high reliability, efficiency, and intelligent control:

Ultra-low harmonics on both the grid and motor sides are achieved without external filters, thanks to a cascaded multilevel topology and phase-shifted rectification.
Critical components include metallized film capacitors with real-time NTC temperature monitoring and neutral-point shift automatic bypass technology, enabling seamless derated operation during cell faults and ensuring an MTBF exceeding 51,221 hours.
Advanced algorithms support flying-start, low-voltage ride-through (LVRT), and synchronous grid connection in harsh industrial environments.
High-efficiency water cooling guarantees continuous full-load operation, while the modular design and Chinese HMI diagnostics significantly streamline maintenance.
The system is certified for a 25-year design life, seismic resistance (Level 7), and wide-temperature operation (-5°C to +40°C), meeting the stringent stability and lifecycle management requirements of petrochemical, power, and advanced manufacturing sectors.

high voltage vfd

Product Technical Specifications

Name	Item	Specification
Input	Power Supply	3-phase 6kV/10kV, Frequency: 50/60Hz
Input	Input voltage range	Voltage：-10%～+10%;Frequency;±2%
Output	Rated Voltage	3-phase 6kV/10kV,Frequency：50/60Hz
	Frequency modulation range	0～50/60Hz
	Setting resolution	0.01 Hz
	Overcurrent capability	120% of rated output current,1m/Every10m; 150% of rated output current for instantaneous protection
Control	Control method	V/F control with PG vector control and without PG vector control.
	Synchronous switching	The frequency converter follows the voltage phase and frequency of the power grid, achieving a state of grid connection and smooth switching from frequency converter to power frequency without impact.
	Torque compensation	Automatic torque boost during startup to reach above 150%.
	Slip compensation	Compensates for speed drop under load to enhance mechanical robustness.
	Upper and lower frequency limits	Upper and lower frequency limits can be set.
	Skip frequency	Skip frequency can be set in 3 groups.
	Speed tracking during restart	The inverter can automatically search for the motor speed and smoothly restart operation when the motor is coasting due to power loss.
	Acceleration and deceleration time	Acceleration and deceleration time can be independently set from 0.1 to 3600 seconds.
Control	Acceleration and deceleration profile types	Linear or S-curve profiles can be selected to meet various application requirements.
	Operating modes	Local operation, on-site operation, remote operation.
	Stopping methods	Option to choose between coasting stop or deceleration stop.
	PID closed-loop control	Can be applied to various closed-loop control systems such as flow, pressure, temperature, and more.
	Neutral drift	By bypassing a power unit and using neutral drift technology, the three-phase output stays balanced. This guarantees maximum output power even after bypassing a unit. In case of a single-unit failure, the system can operate in bypass mode without impacting regular production operations.
	Automatic unit bypass	When a unit malfunctions, the inverter can automatically bypass the faulty unit and continue operating using neutral drift technology without the need for manual intervention. If more than two units are bypassed, users simply need to operate at a reduced capacity as necessary.
	Power failure restart	In the event of an abnormal power outage, the inverter can automatically restart and restore to its pre-power loss state once the grid is restored within the set time, without the need for manual intervention.
	Frequency setting	Analog input signal setting: Configurable via a 4-20mA current signal. Multiple frequency segment selection settings.
	Fieldbus	Modbus,Tcp/ip,PROFIBUS-DP
	Operating state output signal	Relay output: selectable to indicate operating states such as running, stopped, fault, etc. Analog output: selectable to indicate operating parameters such as frequency, current, voltage,speed, etc.
Environment	Place of use	Indoor use, altitude below 1,000 meters, no corrosive or flammable gases; no dust, oil mist, or water droplets; avoid direct sunlight; no strong magnetic field interference. For altitudes above 1,000 meters, derating is required.
	Storage temperature	-5℃～+40℃
	Operating humidity	5～95%RH(non-condensing)
	Vibration	≤0.5g
	Storage temperature	-40℃～+70℃
	Ingress protection rating	IP30

Application Areas

The RNHV high-power, water-cooled high-voltage VFD is designed for precision speed regulation and energy optimization of large-scale motor-driven equipment in industrial sectors, including:

Petroleum and chemical processing
Power generation
Metallurgy
Mining

It controls critical assets such as high-voltage pumps, compressors, and fans by adjusting motor speed to precisely regulate fluid flow, pressure, or temperature. This replaces traditional throttling methods (valves or dampers), substantially reducing energy consumption while meeting high reliability, automation, and intelligent operation requirements for applications such as production lines, power plant auxiliary systems, and compressor stations.

	Power plant Wind turbines, compressors, pumped hydro storage plants, draft fans, condensate pumps, circulating water pumps, boiler feedwater pumps, etc.
	Oil, Petrochemicals, Natural gas Pipeline transfer pumps, injection pumps, feedwater pumps, submersible oil pumps, circulating water pumps, brine pumps, compressors, booster fans, oil transfer pumps, electric submersible pumps, etc.
	Coal, Mining Scale removal pumps, slurry pumps, slag slurry pumps, clear water pumps, feed pumps, axial flow fans, agitation pumps, kiln transmissions, dust removal fans, drainage pumps, media pumps, counter-rotating fans, etc.
	Cement building materials Kiln induced draft fans, kiln forced draft fans, kiln tail fans, kiln head fans, medium-temperature fans, coal mill fans, dust removal fans, circulating fans, raw material grinding fans, cement grinding fans, separator fans, pressure conveying fans, etc.
	Steel and metallurgy Blast furnace blowers, induced draft fans, compression fans, air supply fans, feedwater pumps, water supply pumps, descaling pumps, dust removal fans, converters, blast furnaces, etc.
	Municipal water supply Aeration blowers (for heating, water supply, sewage, etc.), induced draft fans, air supply fans, booster pumps, hot water circulation pumps, sewage pumps, clean water pumps, lift pumps, water supply pumps, reclaimed water pumps, etc.
	Light industry, Chemical industry Coal gas blowers, booster pumps, compressors, axial flow pumps, soft water pumps, water supply pumps, etc.