Devkit for high-performance solar power systems

Solar micro inverters are an emerging segment of the solar power industry. Rather than linking all solar panels in an installation together to a central inverter, solar micro inverter systems place smaller, or "micro," inverters at the output of each individual solar panel. This configuration lends itself to many benefits, including elimination of partial shading conditions, increased system efficiency, improved reliability and greater modularity.

While a solar micro inverter yields many benefits, it also poses complex challenges to designers. Designers must grapple with non-linear characteristics of the solar panel power output, devise technical maximum power point tracking (MPPT) algorithms to maximise the energy delivery, and understand complex power stage design and control. Likewise, they must identify a suitable controller with the performance and flexibility to implement these complex functions that is also straightforward to work with.

The C2000 Solar Micro Inverter Development Kit, based on TI's F28035 MCU, introduces designers to a fully suitable MCU and methodically addresses the application challenges by breaking down the development process into manageable pieces. Users can evaluate the design initially through a simple graphical interface without the need to dive into code development. When ready to explore in further depth, detailed theory-based documentation guides users step by step through the software and hardware implementation by incrementally building from open loop to closed loop operation of the solar micro inverter.

The kit implements control of an active clamp flyback DC/DC converter with secondary voltage multiplier, MPPT and a grid-tied DC/AC inverter, comprising the power conversion stages of the solar micro inverter. It supports panel voltages of 28-45V at input as well as universal power output at up to 280W for 220V AC and up to 140W for 110V AC, making it suitable for the diverse requirements of worldwide solar markets. 93% peak efficiency and less than four percent total harmonic distortion (THD) provide more power output per solar panel, reducing detrimental heat dissipation and increasing system longevity.

The C2000 Piccolo F28035 MCU serves as a high-performance controller for the complete micro inverter system, executing high-frequency control loops for the DC/DC and DC/AC power stages. The single MCU system implementation offers design simplicity and reduced system cost. The MCU operates the inverter at a high PWM frequency of 100KHz to reduce harmonic distortion and lower passive component costs. Integrated features of the C2000 Piccolo F28035 MCU enable efficient control of each power stage: 4.6MSPS 12-bit analog-to-digital converter, low latency C28x real-time processing core and feature-packed, 150ps high-resolution PWM modules.

Complete software source code, hardware design files and detailed documentation allow designers to see and understand exactly how the design was implemented, creating the foundation to begin their own unique solar power implementations. Solar and digital power software libraries provide code-optimised building blocks to implement a variety of power topologies and algorithms such as MPPT and Software Phase Locked Loops (PLL), suited for designing customised solar inverter solutions.

The UCC27531 and UCC27211 high-performance gate drivers used in the kit allow for high efficiency with low propagation delay of 17ns, negative voltage handling for noisy environments and high supply voltage (UCC27531) for switching IGBTs.

The C2000 Solar Micro Inverter Development Kit (TMDSSOLARUINVKIT) is available today for $850 (USD). TI also offers complementary solar development platforms for centralised or string solar inverter topologies: The C2000 High-Voltage MPPT Kit (TMDSHVMPPTKIT) for $550 (USD) and the C2000 High-Voltage Single-Phase Inverter Kit (TMDSHV1PHINVKIT) for $450 (USD). All solar development kits can be purchased now through the TI eStore and come complete with a full suite of software libraries, examples and full reference hardware packages. Designers can begin browsing the software and design resources of these kits for free in the C2000 controlSUITE.