On-Grid Inverter

On-Grid Inverter topology is based on 1 Full Bridge 2 High Frequency IGBT Inverter Modules (3 full-bridge 6 high frequency IGBT modules for 3 Phase output) using PWM (pulse width modulation) and control logic based on DSP. Monitoring of electrical values and parameter adjustments can be done through Graphical Display and Mimic diagram of the PMI On-Grid Inverter system. EMC filters decrease the radio frequency emissions on the AC network and photovoltaic modules while Full Bridge High Frequency IGBT Inverter Modules convert direct current to alternating current. Isolation of DC input and AC output is ensured by galvanic Isolation Transformer at the output of the inverter. No load losses of the transformer is avoided by separating the inverter from AC output by contactor while inverter is in “OFF” position. All operations are controlled through Control PCBs and Graphical Display monitors the whole system.

With an estimated 30 years life time, photovoltaic panels or generators are main source of producing direct cur­rent which is transformed to alternat­ing current via inverters that form the heart of the system as their robust de­sign should ensure the continuity of the supplied energy by also leveling up the output voltage to the electric­ity network voltage of the grid, staying synchronized with the mains frequen­cy. The inverter must as well optimize the energy production with respect to the solar radiation by tracking the Maximum Power Point (MPP). Maxi­mum Power Point Tracking, frequently referred to as MPPT, is a system that operates the Photovoltaic (PV) mod­ules in a way that allows the modules to produce all the power they are ca­pable of.

The sizing of photovoltaic panel pow­er is generally more than the maxi­mum power supplied by the inverter in order to offset the loss of power of the PV modules due to high operat­ing temperature, dirt, cables and age­ing. To obtain the desired power it is possible to connect more inverters in parallel to the Grid. Utilizing more inverters means placing more MPPTs with the result of being able to run each unit separately, optimizing the configuration and consequently the performance of the entire plant. Fur­thermore in the event of inverter mal­function, only the part involved in the malfunction is affected and not the entire production as in the case of the single inverter.

  • Optimum power distribution independent of each phase voltage
  • 6 pulse IGBT module topology
  • Low filter loss thanks to 20 kHz switching frequency
  • High conversion efficiency
  • High accuracy MPPT technology
  • High yield at low irradiance levels
  • Automatic reactive current and power factor control
  • Sinusoidal inverter output with < 3 % total harmonic current distortion (ITHD)
  • Display advanced parameter graphical display
  • Short Circuit, Over Current, Over Voltage Protections at Output
  • Thermic Over Current Fuse with Indicator, DC Over Voltage and EMI-RFI Filter at Input
  • More than 200.000 hrs MTBF with More than 20 years life time
  • Industrial grade front access cabins, easy maintenance
  • Customized output isolation transformer design to suit different voltage levels and frequency
  • Advanced communications via Modbus TCPIP or Modbus RTU with local or remote configuration and monitoring
  • Power ratings from 10 kW up to 200 kW with N+1 configuration
  • Full nominal power up to 45 °C Smart fan controlling system to optimize the efficiency
TopologySix Module IGBT High Frequency Switching Inverter With Output Isolation Transformer
Control DS PIC Controlled
1Phase Power Options6 / 10 / 20 / 30 /40 kW
3Phase Power Options10 / 20 / 30 / 40 / 60 / 80 / 100 kW
Overall Efficiency>90% (1 Phase) / >93% (3 Phase)
Over Load Capacity10 min for 110%
Isolation Voltage2.500 VAC (Input-Output, Input-Chassis, Output-Chassis)
Grid DC ConnectionSequence Rail Terminal (+/- DC)
Input DC Voltage, MPPT300-350 VDC (1 Phase) ; 500-600 VDC (3 Phase)
Min-Max Input DC Voltage250-450 (1 Phase); 300-700 (3 Phase)
Input ProtectionThermic Over Current Fuse With Indicator, Over Voltage and EMI-RFI Filter
Instant Voltage and Pulse ProtectionIEEE 587 (4500 A, 110 Joules)
Output Voltage220/230 VAC (1 Phase) ; 380/400 VAC (3 Phase, Each phase output power independently controlled)
Output Voltage Tolerance±10%
Output Frequency50 – 60 Hz (On request)
Output Frequency Tolerance±2% Synchronized on Mains
Output WaveformFully Sinusoidal, THD <3%
Output ProtectionShort Circuit, Over Current, Over Voltage and Over Temperature
Output TransformerGalvanically Isolated
Grid Number 1 Phase12 Grid In Series, MPPT Grid Voltage 26-28 VDC, 10 Grid In Series, MPPT Grid Voltage 33-36VDC
Grid Number 3 Phase20 Grid In Series, MPPT Grid Voltage 26-28 VDC, 16 Grid In Series, MPPT Grid Voltage 33-36VDC
Indicator and ButtonsGraphic LCD Panel, Menu Select and Menu Set Buttons
Warning MessagesInput Fuse/Operating Mode/Inverter Synchronization/DC Input High- Low/Inverter Over Load/Internal Over Temperetaure /Inverter Over Temperature/IGBT SCR Fuse Fail/Inverter Output High-Low
Viewing Measured ValuesOutput Voltage/Output Frerquency/Inverter Load Level/DC Bus Voltage/Internal Temperature /Event History
Adjusting ParametersDate/Time /Alarm Sound Level/Communication Slave Number/Led Test
Sound AlarmOn Warning Messages 2 Short ‘beep’ per 2 seconds
CommunicationRS 485 – Modbus – TCP/IP communication are available to monitor and remote parameter setting (Optional)
Protection devices and environmental conditions
Access to CabinFront Access
Level of protectionIP 21 as Standard; IP42 with Front Access as Option
Permitted temperature range<95%
Maximum height above sea level1000 m ASL

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