Smart VFD / Inverter | Products — SGT Systems Limited

Overview

Smart VFD / Inverter is an IoT-connected variable frequency drive that controls the speed and torque of three-phase induction or PM motors while continuously reporting energy, current, voltage, vibration, and fault data to your SCADA, historian, or cloud. Replaces simple DOL starters and dumb VFDs with a device that pays for itself in saved kWh and avoided breakdowns.

Engineered for plants where pumps, fans, conveyors, compressors, and machine spindles run far below their nameplate load most of the day. A typical 22 kW pump on a soft VFD with closed-loop pressure control saves 25–45 % of its electricity bill and extends bearing life by 2–3×.

0.4–630 kW range — 1-phase 230 V, 3-phase 400 V, 690 V, with regen options
Sensorless vector control — full torque from 0 Hz without an encoder
Built-in energy meter — kWh, kVAR, PF, demand peak, ISO 50001-ready
IoT-native — Modbus, Profinet, EtherNet/IP, OPC UA, MQTT to cloud

How It Works

The drive rectifies the incoming AC to DC, then synthesises a three-phase variable-frequency, variable-voltage output through an IGBT bridge under SVPWM control. A sensorless vector algorithm estimates rotor flux and slip to deliver full torque even at standstill. Every cycle, the drive measures phase currents and DC bus voltage, runs fault protection, and streams telemetry north.

Setpoint in — from PLC over Modbus / Profinet / 0-10V or from local keypad
PID + vector calc — rotor flux estimation, current/voltage decoupling, slip compensation
SVPWM modulation — 2–16 kHz carrier into the IGBT bridge, dead-time controlled
Protection layer — overcurrent, overtemp, DC-bus, phase loss, ground fault, stall
Telemetry north — kWh, current, vibration, fault history to historian / cloud

Features

Sensorless vector — full rated torque at 0.5 Hz, no encoder required
Built-in PID — close pressure / flow / temperature loops without a separate PLC
Energy savings report — kWh vs DOL baseline, ROI calculator, CO&sub2; equivalent
Vibration-based diagnostics — integrated MEMS or external accel input, bearing-wear alarm
Multi-protocol fieldbus — Modbus TCP/RTU, Profinet, EtherNet/IP, OPC UA, MQTT
Safe Torque Off (STO) — SIL 3 / PLe certified safety input, no contactor required
Regen / brake chopper — recover braking energy on hoists, centrifuges, cranes
Mobile commissioning — Bluetooth + phone app for setup, trend, fault clear

Use Cases

Pumps & fans — cubic-law energy savings, soft start, water-hammer elimination
Conveyors — speed sync to upstream/downstream, jam-soft-stop
Compressors — replace load/unload with continuous variable-speed for > 30 % savings
HVAC AHUs & chillers — demand-based airflow / chilled-water flow
Machine spindles — precise speed under varying cutting load
Hoists / cranes — regen braking, holding torque, anti-sway

Specifications

Power range: 0.4 / 0.75 / 1.5 / 2.2 / 4 / 5.5 / 7.5 / 11 / 15 / 22 / 30 / 45 / 75 / 132 / 250 / 400 / 630 kW
Input: 1× 200–240 V or 3× 380–480 V / 525–690 V, 50/60 Hz, ±10 %
Output: 0–599 Hz, 200 % overload 3 s / 150 % 60 s, sensorless vector / V/f
Control: Sensorless flux vector, closed-loop vector with encoder, V/f, V/f with slip comp
Fieldbus: Modbus TCP/RTU, Profinet, EtherNet/IP, EtherCAT, CANopen, OPC UA, MQTT
Safety: STO SIL 3 / PLe standard; SS1, SLS, SBC options
Environment: IP20 / IP55 / IP66 cabinet; −10 to +50 °C without derating
Compliance: CE, UL 508C, EAC, IEC 61800-3 EMC, IEC 61800-9 efficiency class IE2