1-phase string inverter solutions
Single-phase string inverters perform power conversion on series-connected photovoltaic panels. Usually, these inverters are rated around a few kilowatts up to 10 kilowatts. In general, most inverter designs are transformerless or non-isolated. String inverters typically rely on two-stage power conversion. First, the DC-DC stage converts variable DC voltage into a fixed DC voltage while simultaneously ensuring maximum power has been extracted from the PV panel via the MPPT (Maximum Power Point Tracking) technique.
DC-AC stage converts DC power into grid-compatible AC power. 2-level or innovative topologies like HERIC, H6 & Multilevel are preferred in this stage. When a 1-phase string inverter is connected to a 600 V PV array, HERIC and H6 topology are preferred due to their higher efficiency, lower system cost, size, and weight. The size and weight of the inverter highly depend on the AC filter size and cooling system, so a higher switching operation is desirable to reduce the size and cost of the system. Therefore, wide bandgap solutions are desired for system design in the DC/AC stage.
Infineon offerings for designs up to 10 kW
In the residential market, inverter design ranges from 1 kW up to 10 kW. It is possible to achieve the best price for performance by using Infineon’s discrete products. This includes our OptiMOS™, CoolMOS™, CoolSiC™ MOSFET, CoolSiC™ Schottky diodes,
CoolGaN, IGBT TRENCHSTOP™5-7. To reduce complexity for designers in multilevel implementations, sometimes module solutions are chosen, for example, in the highly flexible easy 1B/ 2B package. Since every switch needs a driver, and every driver needs to be a controller, we also offer the matching EiceDRIVER™ gate driver as well as XMC™ or PSoCTM microcontrollers for string inverter designs. Finally, each functional block needs a sensor and auxiliary power supply, so we offer CoolSET™ together with 1.7 kV CoolSiC™ and the TLI4971 current sensor. OPTIGA™ products complete the portfolio and ensure data protection and security.
Infineon’s solutions support inverter designs for a long lifetime, with highly efficient power conversion, accurate current measurement, and low output distortion.
Find the right product combination to design your 1-phase string inverter power stage here:
- In the residential market, more safety requirement features and remote control are a clear trend. Monitoring real-time system information from anywhere internet connection is necessary to simplify operation and maintenance services. In addition, the inverter manufacturer has to fulfill the personal and property safety standards by integrating the rapid shut down feature. We see a clear trend toward increasing demand for the power optimizerat the module level.
- Another trend is seen towards inverters with multilevel topologies. Such inverters can utilize lower voltage switches like OptiMOS™ MOSFET. The reduced conduction losses combined with reduced switching losses make it possible to reach higher efficiency compared to traditional inverters. The drawback is the greater level of complexity necessary to realize a multilevel design compared to conventional topologies and the higher number of switches and isolated gate drivers needed. However, at a certain power level
- in the 3 kW to 5 kW range, the benefits of the multilevel design, such as the reduction in size and weight and higher efficiency and power density, justify the added complexity.
- For higher power solutions up to 10 kW hybrid topologies for string inverter, utilizing CoolSiC™ and TRENCHSTOP™ IGBTs simultaneously are in favor. Through them, circuit design can be optimized for switching and conduction losses while keeping an attractive solution cost range.
- Recently, the focus on smart systems in residential and small commercial systems has grown tremendously. The reason for this is rising energy prices and the wish to increase self-consumption of PV to become independent from the public power grid. A good way to efficiently and decentralize systems is using hybrid inverter designs to integrate and operate an energy storage system together with the PV installation.
Innovative 5-level hybrid inverter topology
Achieve ultra-high efficiency peaking at over 99% and providing >98.5% efficiency over a wide load range with minimal power losses distributed among SMD MOSFETs. This enables operation at maximum load without heatsinking or the need for forced air cooling.
To prove the benefits in real life, Infineon designed the EVAL_4kVA_230VAC_5LINV 5-level active neutral point clamped flying capacitor (ANPC-FC) inverter evaluation board. The multilevel inverter is based on 150V OptiMOS™ 5 technology, with low RDS(on) and Qrr.
This hybrid reduces size and weight for solar inverters, string inverters, and general-purpose inverters.
myInfineon: Join now and enjoy the benefits
New whitepaper: Silicon carbide MOSFETs for next-level power density in solar and energy storage
The latest generation silicon carbide semiconductors and CoolSiC™ MOSFETs enable a significant increase in power conversion efficiency in solar power generation systems and associated energy storage. Read more about these applications and how lower loss not only saves energy, but also results in smaller and lighter equipment with lower capital, installation, and maintenance costs.
Application presentation: Exploiting the unlimited potential of Solar energy
This presentation gives you an overview of topologies, technological trends, and requirements of solar applications. Find out more about our offering for each inverter type – from the microinverter to the central and string inverter. Check our recommendations for your application, and you get your customized module in a five-month timeframe.
On-demand webinar: From solar and wind to energy storage
In the webinar, you will gain insight into renewables and the emerging applications of energy storage. Learn more about application trends and requirements, and understand Infineon's solution offerings for these applications.
The benefits of an optimal system solution
Let’s learn more about how solar inverters work, from the ones we have in our houses, to the ones that are applied in major factories. We will also see how Infineon innovates in power semiconductors for solar inverter technology and how that can help with reducing costs and time to market.
Take this course to learn about the multilevel inverter demo board, targeting applications where efficiency and power density are critical.
