Surge control system for a compressor

A system for supplying compressed air to a combustion engine so as to promote power output by the combustion engine, said system comprising:

• a compressor having at least one inlet and at least one outlet, said inlet connected in fluid communication with an ambient air intake and said outlet in fluid communication with an engine intake;
• a recirculation line having a first end connected in fluid communication with the compressor outlet and a second end connected in fluid communication with the compressor inlet;
• an air cooling device connected in fluid communication with the recirculation line and capable of cooling recirculated air upstream of the compressor inlet;
• a recirculation valve disposed in the recirculation line and operable to control rate of flow through the recirculation line, the recirculation valve being controllable via control signals;
• a programmed controller in communication with the recirculation valve and programmed to send control signals to the recirculation valve to open the recirculation valve so as to recirculate compressed air through the recirculation line to the compressor air inlet when the engine is operating below a threshold engine speed, and to maintain the recirculation valve closed so as to prevent recirculation when the engine is operating above said threshold engine speed;
• and
• an air mixing device connected in fluid communication with the recirculation line between the air cooling device and the compressor inlet wherein the air mixing device is capable of mixing the cooled air and the ambient air upstream of the compressor housing inlet so as to reduce occurrence of compressor surge.

A method of actively controlling compressor surge in an engine system wherein air is compressed in a compressor and supplied to an intake of an internal combustion engine, said surge controlling method comprising:

• supplying air to an inlet of the compressor;
• compressing the air in the compressor;
• discharging compressed air from the compressor through a compressor discharge line to the intake of the internal combustion engine;
• providing a recirculation line connecting the compressor discharge line to the compressor inlet;
• providing a controllable recirculation valve in the recirculation line for controlling an amount of flow through the recirculation line;
• opening the valve and recirculating compressed air from the compressor discharge line to the compressor inlet when the engine is operating below a threshold engine speed, and maintaining the valve closed so as to prevent recirculation when the engine is operating above said threshold engine speed;
• cooling the recirculated air;
• and
• feeding the cooled recirculated air back to the compressor inlet.