IIT Goa is one of the premier institutes of India established with missionto impart knowledge and provide unique learning experience to prepare students to be responsible leaders, managers, entrepreneurs, and professionals who will play a leading role in the sustainable development of Goa and the nation as a whole.
Ecosense supplied a customised DAB converter to Indian Institute of Technology, Goa.
What is DAB converter?
A bidirectional DC-DC converter called a dual active bridge (DAB) has identical full bridges on the primary and secondary sides, a high frequency transformer, an energy transfer inductor, and DC-link capacitors. The term "energy transfer inductance" in the model refers to both the transformer's leakage inductance and any required external energy transfer inductance.
Both full-bridges' two legs are driven by complementary square-wave pulses. By employing phase shift modulation to phase-shift the pulses of one bridge with respect to the other, power flow in the dual active bridge can be controlled. In order for the leading bridge to supply power to the lagging bridge, the control directs power between the two DC buses. The energy transfer inductance's stored energy is directed by the voltage differential produced across it by the square waves that are delivered to the bridges.
In ideal cases with dual active bridge converters, zero voltage switching (ZVS) can be realized when the voltage transfer ratio (M) across the transformer is equal to 1:
M = Vout / (n*Vin)
where, n is the transformer turn ratio, Vout is the output voltage and Vin is the input voltage.
In non-ideal cases, ZVS depends on the resonant relationship between the output capacitance across each device and the equivalent inductance of the circuit during different switching intervals. During switching events, the current through one of the complimentary devices is interrupted, but due to the energy transfer inductance, current is supplied through the output capacitor and forced through the anti-parallel diode of the device.
Each switch is on for 50% of its respective switching period. The switch pairs in the two bridges all have the same switching period but are operated such that between each bridge a phase shift is introduced that varies based on the modulation derived from feedback measurements. An output voltage error signal is generated based on a set point value and this is fed through a digital PI regulator to generate the phase shift ratio for the PWM modulator.
Ecosense supplied a customised DAB converter to IIT Goa
The way forward
After initial tests are done the faculty and students at IIT Goa will use the converter for their research.
Demonstration of Converter
Engineers of Ecosense demonstrated the capabilities of the equipment(s) using LabVIEW and FPGS Controller.