Efficiency is one of the major challenges that solar energy installations must address – not only from a technical, but also from an economic standpoint.
Cost-optimized driver solutions are realized using Power Integrations' highly-integrated SCALE and SCALE-2 gate drivers, which enable a significant reduction in both component count and PCB size over typical solutions based on discrete driver stages. Integration also results in increased reliability as fewer components means less potential causes for malfunction. Therefore, the overall system MTBF (Mean Time Between Failure) is improved using SCALE and SCALE-2 gate drivers.
Fig. 1 Cost/performance improvement through integration
One of the technical challenges related to solar applications concerns over-voltage protection.
During normal operation – when the load is connected at standard temperatures - the DC-link voltage of a solar inverter is relatively low compared to the maximum blocking capability of the power switches. Therefore, there is enough voltage ‘headroom’ to handle any over-voltages that may occur when the power switches are turned off. Reliable protection of these switches using active clamping methods is, therefore, easy to achieve.
However, the open circuit voltage of a solar inverter (more precisely, of the solar panels), in particular at low temperatures, can lead to an increased DC-link voltage close to the maximum blocking capability of the power switches. During this period any standard active clamping circuit could cause an unintended turn-on of the power switches. In the best case, this would result in additional losses and increased EMI - however in a worst-case-scenario the result could be the complete destruction of the solar converter.
To address this situation, Power Integrations has developed a sophisticated active clamping technique, named ‘Dynamic Advanced Active Clamping (DA²C)’, which activates and deactivates the clamping function automatically, allowing solar inverter to operate safely under all application conditions (see figure 2).
Fig. 2 Dynamic Advanced Active Clamping (DA²C)