Soft-starter AC-AC converter with integrated solid-state circuit breaker and method of operation thereof

An AC-AC power converter comprising:

• an input connectable to a line terminal of an AC source;
• an output connectable to a load terminal of an AC load;
• one or more supply lines connecting the input and output to transmit power from the AC source to the AC load, each supply line corresponding to a phase in the AC load;
• a plurality of solid-state switching blocks each including an arrangement of solid-state switches, with or without accompanying diodes, that form a bi-directional switching block that controls current and withstands voltage in both directions;
• and
• a controller operatively connected to each of the plurality of solid-state switching blocks, the controller programmed to selectively switch the solid-state switches in the plurality of solid-state switching blocks between conducting and non-conducting states to enable full speed operation of the AC load, soft-starting of the AC load at a voltage less than a full speed operation voltage, and selective interruption of current flow through the AC-AC power converter in a solid-state circuit breaker function;
• wherein the plurality of solid-state switching blocks comprises:
• in-line switching blocks connected between the input and the output of the AC-AC power converter, such that each supply line includes only one of the plurality of in-line solid-state switching blocks connected thereto;
• and
• free-wheeling switching blocks connected to the output of the AC-AC converter at one end and together at a common connection at another end, such that each supply line includes only one of the plurality of free-wheeling solid-state switching blocks connected thereto;
• and
• wherein the controller is programmed to selectively interrupt current flow through the AC-AC power converter in the solid-state circuit breaker function by:
• identifying a fault condition in the AC-AC power converter based on one or more of voltage values and current values received thereby;
• and
• switching each solid-state switch in the arrangement of solid-state switches in the in-line switching blocks to the non-conducting state, so as to interrupt current flow through the in-line solid-state switching blocks.

A method of operating an AC-AC power converter, the method comprising:

• receiving an AC power at an input of the AC-AC power converter;
• comparing, via a controller, one or more current and voltage parameters of power provided to the AC-AC power converter or present in the AC-AC power converter and acquired by one or more voltage or current sensors, to one or more respective current and voltage thresholds;
• identifying, via the controller, a fault condition in the AC-AC power converter if the one or more measured or determined current and voltage parameters exceed the one or more respective current and voltage thresholds;
• and
• controlling, via the controller, a solid-state circuit breaker integrated into the AC-AC power converter to interrupt current flow through the AC-AC power converter upon identification of the fault condition, the solid-state circuit breaker comprising a plurality of solid-state switching blocks connected between line terminals and load terminals of the AC-AC power converter, with each of the solid-state switching blocks including:
• a pair of solid-state switches connected with one another in anti-series;
• and
• a pair of diodes each connected in anti-parallel with the pair of solid-state switches, with the pair of diodes further connected in anti-series with one another;
• wherein controlling the solid-state circuit breaker to interrupt current flow comprises switching each of the pair of solid-state switches in each respective solid-state switching block to a non-conducting Off state, so as to interrupt current flow through the AC-AC power converter;
• and
• wherein the plurality of solid-state switching blocks comprises:
• in-line switching blocks connected between the line terminals and the load terminals, such that each supply line includes only one of the plurality of in-line solid-state switching blocks connected thereto;
• and
• free-wheeling switching blocks connected to the load terminals at one end and together at a common connection at another end, such that each supply line includes only one of the plurality of free-wheeling solid-state switching blocks connected thereto.