Open-Switch Fault-Tolerant Operation of a Two-Stage Buck/Buck–Boost Converter With Redundant Synchronous Switch for PV Systems

Abstract

In PV systems, DC-DC converters have been identified a s o ne o f t he m ost c ritical a nd c hallenging subsystem in terms of failure rate. Thus, this paper proposes fault tolerant operation of a two-stage Buck/Buck-Boost converter under open-circuit switch failure. Remedial actions are efficient in any failure of one of the two switches of the converter. Here, a new unified approach is considered, for the overall fault tolerant operation of the two stages of the converter. The fault tolerant circuit we propose lies on performing redundancy by implementing the equivalent synchronous switch for the two main switches of the two stages, in offline m ode. T he f ault t olerant c ircuit results from the basic two-stage Buck/Buck-Boost converter and its equivalent circuit with a synchronous switch, merged together to form the new DC-DC fault tolerant circuit.Therefore, post-fault operation at full power can also be performed. By using a switch fault management unit with reduced complexity, inserted between the control block and the switches, we have designed an unified, e fficient and optimized fault tolerant control, suitable in both healthy and post-fault operations. Some selected experimental tests, which all confirm t he g ood p erformances o f t he proposed fault tolerant approach, are presented and discussed.

Common Switch Fault Diagnosis for Two-Stage DC-DC Converters Used in Energy Harvesting Applications

“…The contribution of this paper focuses on the first step-the fault detection. Nevertheless, to validate the proposed UFD, it is applied to a fault-tolerant two-stage DC-DC converter, here, the buck/buck-boost two-stage converter studied by Siouane et al [28]. Furthermore, the fault operation was also verified, based on the proposed UFD.…”

“…In these papers, observation of the inductor current shape according to the switching pattern is the base of all the proposed FD methods. Moreover, only a few papers have proposed remedial actions and fault-tolerant circuits for two-stage DC-DC converters [28]. In [28], a fault-tolerant cascaded buck/buck-boost converter with energy storage was recently examined under synchronous control, but fault detection was not discussed.…”

“…Then, a shared redundant switch (SW R in Figure 3) associated with the two diodes D 3 and D 4 replaced these two switches SW 1 and SW 2 . After this remedial action, the post-fault operation was done by applying a new synchronous control system to the redundant switch SW R (the red one) [28]. focuses on the first step-the fault detection.…”

“…For the studied converter, the post-fault reconfiguration strategy is the same, regardless of the fault localization. In post-fault operation and under synchronous control, the duty cycle d and the frequency f will be sent to the PWM block to generate the switching pattern u applied to the redundant switch SW R (see Figure 3) in order to drive the overall system [18,28]. Therefore, to guarantee service continuity of the system, we just need to detect the fault occurrence and thus, the UFD method is more suitable.…”

A Zeta‐based switched‐capacitor DC‐DC converter topology

“…These days, among the most well‐known power electronics–based circuits are DC‐DC converters, on which both researchers and industries have been interested for numerous applications . Until now, many kinds of DC‐DC converters have been introduced such as buck‐boost, boost, and buck converters . Introduction of converters such as SEPIC, Zeta, and Cuk made power applications possible owing to their capability of generating higher output voltages by employing lower input voltages .…”