ABSTRACT:
In this paper, two Z-network plus switched-capacitor
based DC-DC boost converters (ZSCBC) are proposed. The integration of the
Z-network with switched-capacitor is responsible for yielding a high voltage
gain and that too at lower duty ratios compared to the conventional quasi
Z-source DC-DC converter (QZSC). Since the proposed converters contains Z or impedance-network,
the operating duty ratio is less than 0.5 like in QZSC and retains its
advantages such as common ground and low voltage stress on Z-network
capacitors. Unlike QZSC, the switch and all the diode voltage stresses in the
proposed converters is low even at high voltage gains. A detailed steadystate analysis
is presented to identify the salient features of the proposed Z- network based
boost converter and thereafter compared with other Z-source based
configurations. Small-signal analysis is established and a single-loop voltage
mode controller is designed. A 48 to 250 V, 130 W prototype is built to demonstrate
the effectiveness of the ZSCBC. The steady-state and closed-loop response
measurements validate the theoretical studies.
KEYWORDS:
1.
Boost
converter
2.
Switched-capacitor
3.
Quasi-Z source
DC-DC Converter
4.
Z-source Inverter
SOFTWARE:
MATLAB/SIMULINK
Two
Z-network plus switched capacitor based DC-DC boost converters (ZSCBC) were
proposed in this paper exhibiting voltage gain higher than QZSC while keeping
the main advantages of QZSC intact such as low Z-network capacitor voltage
stress, common ground and wider duty ratio range. The steady-state analysis of
the ZSCBC and its comparison with other reported Topologies-1 to 7revealed that
(i) the voltage stress of the switch and all the diodes is equal irrespective
of their physical location, (ii) lower switch and diodes stress even at high
voltage gain, and (iii) voltage gain enhancement through addition of a
diode-capacitor network. Unlike the proposed converter, the Topologies-1 to 6
unable to incorporate the voltage gain enhancement feature. Detailed analysis
was established and a single-loop voltage-mode controller was designed to
ensure closed-loop stabilization of ZSCBC. Experimental measurements
demonstrated the effectiveness of PID-type controller in terms of regulation against
sudden changes in the load and source voltage. Furthermore, the controller
designed was equally effective in rejecting low frequency disturbances present
in the source.
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[1]
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[3]
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[4]
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