KACO Powador Solar Inverter: The transformerless, three-phase inverters Powador 12.0 TL3 to 20.0 TL3.
Photovoltaic systems of up to several hundred kilowatts can be designed extremely flexibly in small, highly efficient units with the transformerless, threephase Powador 12.0 TL3 to 20.0 TL3 inverters. They operate using two separate MPP trackers that can handle both symmetrical and asymmetrical loads to allow for optimum adjustment. In light of the growing residential solar market we determined it worthwhile to see how Kaco optimized their transfomerless Powador inverter.
The inverter has a transformerless topology to reduce the size and weight. Replacing the isolationprovided by the transformer, the inverter made use of Integrated chips to meet regulatory standard, IEC62109 for safety. The KACO Powador Model 14.0 TL3 is a true three-phase solar inverter with sinusoidal 120-degree phase-shift AC output of 12.5 kVA. The 14.0 TL3 is extremely flexible and decentralized, making it ideal for medium-size commercial solar power systems up to 14kW. The inverter has two separate maximum power-point trackers (MPPTs), which allow you to meet all typical requirements of complex designs – such as the full configuration of an east/west-facing roof.
The inverters switch to the grid, anytime output falls below 250 V. While in operation, they still feed in at outputs as low as 200 V – for the highest possible solar yields all year round. The units are fitted with a data logger and web server to monitor the system, a display for showing operating data and a USB port for running updates or reading out log data.
Teardown: Model: Powador 14.0 TL3
Features
- Up to 98.0% efficiency
- 2 MPP trackers, symmetrical or asymmetrical loadingWide MPP range
- Preconfigured country settings
- Compact design
- DC connection via solar connectors
- Multilingual menu, graphical display
- Data logger with web server
- Quick start-up using the display saves time and cuts costs
External and Enclosure
- Size 690 x 420 x 200 mm and weight 40 kg
- Protection Class IP65 with ambient temperature from -25°C to 60°C
- Aluminum casting case
Main Controller Board
- PWM motor control: TI TMS320F28035PNS Piccolo Microcontrollers. High efficiency 60MHz 32-Bit CPU with enhanced control peripherals for ePWM and High-Resolution PWM (HRPWM).
- Digital Signal Processing: TI TMS320F28335ZJZA Delfino Digital Signal Controller. High performance 150MHz 32-bit floating-point CPU for advanced closed-loop control.
- Isolation:
- Broadcom (Avago Technologies) HCPL-2531 (2pcs) 1Mb/s, 5kV dual channel digital optocoupler. UL Recognized – 3750 V rms for 1 minute.
- Communication: NXP TJA1040 1MBaud CAN transceiver compatible with ISO 11898 standard. Differential receiver with high common-mode range for Electromagnetic Immunity (EMI). Transceiver in unpowered state disengages from the bus (zero load).
- Line Drivers: TI 74ACT16244 16-bit buffers to improve the performance and density of 3-state memory address drivers, clock drivers, and bus-oriented receivers and transmitters. 500-mA Typical Latch-Up Immunity at 125°C.
Power Electronics Board
- Booster & Inverter:
- Vincotech V23990-P629-L99-PM 1200V/40A flowBOOST 0 dual NPT IGBT in booster topology with SiC diodes in flow0 module. Kelvin Emitter for improved switching performance.
- Vincotech 10-F006NPA070FP-P969F09 (3pcs for 3-phase inverter), 1200V/75A flowNPC 0 parallel NPT IGBT in 3-level NPC topology diodes in flow0 module. Kelvin Emitter for improved switching performance. Neutral Point Clamped Topology (I-Type) and parallel switch
- Gate Driver: Broadcom (Avago Technologies) ACPL-332J (12pcs for 3-phase inverter. 2pcs for booster stage). 2.5A output current IGBT gate driver optocoupler with integrated (VCE) desaturation detection, fault status feedback and active Miller clamping.
- Current Sensor: LEM CAS 15-NP (3pcs 3-phase inverter. 2pcs for booster stage) 15A one-channel flux gate, closed-loop bidirectional current transducer module. Accuracy of 0.8%. Max operating temp 85° C, with a minimum of -40° C. Sensitivity of 41.67 mV/A.
- Leakage Current Sensor: VAC N4646-X950 300mA AC/DC differential current sensor, for monitoring of the leakage currents against ground of the entire system. Self-monitoring and test functions. Measuring accuracy 1.5%.
- Load Relays: Panasonic ALFG2PF12 (8pcs) 1Form A 22A/33A power relays used for safety cutoff on the grid power network. High-insulation resistance. Min. 9.5mm creepage distance between contact and coil. 8mm Min. clearance between contact and coil.
- DC Bus Bulk Capacitor: EPCOS B43504-S5567-M2 (12pcs). 500V/560µF electrolytic capacitor.
Charge/discharge-proof, polar. Aluminum case, fully insulated with PET. Overload protection by safety vent on the base.Block Diagram
User Interface and Communication Board
- User Interface controller: NXP LPC2468FET208 Single-chip 16-bit/32-bit microcontroller with 512 kB flash, Ethernet, CAN, ISP/IAP, USB 2.0 device/host/OTG interface.
- Memory:
- ISSI (Integrated Silicon Solution Inc) IS42S16800F-7TLI 128Mb SDRAM. Fully synchronous; all signals referenced to a positive clock edge.
- Cypress (Spansion) S34ML01G100TFI000 1Gbit SLC NAND Flash Memory. Min operating temp -40°C and max operating temp 85°C.
- Ethernet Communication: Microchip KSZ8001LI 100Mbps Ethernet controller. 1.8V CMOS design, power consumption 250 mW. Fully compliant to IEEE 802.3u standard.
- Line Drive: TI SN74ABT541B octal buffer & line driver. State-of-the-art EPIC-IIB™ BiCMOS design significantly reduces power dissipation. Typical VOLP (Output Ground Bounce) < 1 V at VCC = 5 V, TA = 25°C. High-impedance state during power up and power down.
Solutions for any Installation
The KACO Powador line comes in an enormous array of configurations, suitable for small-to-large installations both on-grid and off. If the 14.0 TL3 model used in this teardown is not an ideal solution for a particular site, then designers can almost certainly find another model in the Powador line which would pair perfectly for any project.
In conclusion, these inverters provide you with extreme flexibility when designing your PV sys-tem. They operate using two separate MPP trackers that can handle both sym-metric and completely asymmetric loads to allow for optimum adjustment. We hope you find this analysis of value. If you have any comments or questions please email us at [email protected]
Filed Under: Product design