Structures of Redundancies and Reconfiguration Principles of Voltage Source

Historically, operational safety techniques in electrical power conversion systems were initially proposed for three-phase electrical machines vulnerable to the loss of an external phase (disconnection or cutting of a supply cable between the voltage inverter and the three-phase machine) or to an internal inverter fault (open-circuit or short-circuit type fault, control fault...) [D3179] . A conventional three-phase voltage inverter topology incorporating auxiliary isolation switches can tolerate an internal fault, but the performance of the electric machine in standby mode, in this case single-phase, is not satisfactory for all the applications envisaged: significant reduction in power, strong torque ripples, uncertain machine start-up depending on the position of the rotor at standstill. As a result, in order to maintain power system continuity in terms of torque and power performance, families of fault-tolerant voltage inverter structures have been proposed, and are listed below:

• voltage inverter structures without redundancy ;

• voltage inverter structures with active redundancy of power components ;

• voltage inverter structures with passive redundancy of power components ;

• voltage inverter structure with redundancy in the power system ;

• voltage inverter structure with redundancy through mutualization of power components.

The first family uses no additional power components beyond those used in normal operation (drivers, switchgear, power switches) [D3176] . In this case, only degrees of freedom at the input DC bus voltage source (e.g. a midpoint or split sources) or at the load (e.g. a common or neutral point, separate terminal windings) are permitted. On the other hand, voltage inverter structures with redundancy, which will be explained in greater detail in section 2, include a surplus of so-called "passive" or "active" switching cells from the normal operating mode onwards, adding additional degrees of freedom to those naturally present in the source and load, which can be used to improve...