An optimal current observer for predictive current controlled buck DC-DC converters.

Area of Science:

• Electrical Engineering
• Power Electronics
• Control Systems

Background:

• Conventional current sensors in digital current mode controlled DC-DC converters face limitations in isolation, cost, power loss, and size.
• Current observers offer a potential hardware-independent alternative but suffer from divergence issues due to parasitic elements and diode characteristics, leading to output voltage errors.

Purpose of the Study:

• To propose an optimal current observer for digital DC-DC converters that enhances current observation accuracy.
• To implement and validate the proposed observer in a buck converter for improved performance and reduced system overhead.

Main Methods:

• Development of an optimal current observer algorithm that compensates for known parasitic resistors and diode forward conduction voltage.
• Integration of the optimal current observer with a predictive current controller for a buck converter.
• Experimental validation of the proposed system's performance, including current observation accuracy and transient response.

Main Results:

• The optimal current observer achieves highly accurate inductor current observation by compensating for parasitic parameters.
• The implemented buck converter demonstrates superior transient response compared to conventional voltage mode controlled converters.
• Significant reductions in cost, power loss, and size are achieved due to the elimination of external current sensing hardware.

Conclusions:

• The proposed optimal current observer effectively addresses the divergence issues in digital DC-DC converters.
• This approach offers a cost-effective, efficient, and compact solution for current sensing in power electronics applications.
• The experimental results confirm the practical viability and performance benefits of the optimal current observer-based control strategy.