Optimized control of a water pump in an automatic beverage preparation machine

Automatic beverage preparation machine, comprising:

• a brewing assembly comprising a brewing chamber to contain a dose of a powder product;
• a hydraulic circuit to supply a brewing liquid to the brewing chamber to prepare a beverage from the powder product in the brewing chamber and comprising a pump and a flow meter to measure an amount of brewing liquid supplied to the brewing chamber;
• and
• an electronic control unit configured to communicate with the flow meter to receive an output thereof and with the pump to control operation thereof;
• wherein the electronic control unit is further configured to control the pump to carry out a beverage preparation cycle comprising a pre-brewing phase during which the brewing liquid is supplied to the brewing chamber to pre-brew the powder product contained therein, followed by a dwell time during which no brewing liquid is supplied to the brewing chamber, and a subsequent brewing phase during which the brewing liquid is supplied to the brewing chamber to brew the powder product contained therein and at the end of which the prepared beverage is delivered;
• wherein the electronic control unit is further configured to:
• store functional data required to control operation of the pump during a beverage preparation cycle;
• and
• control the pump based on the stored functional data during one or both of the pre-brewing and brewing phases by implementing one or both of the following controls:
• pre-brewing phase:
• open-loop controlling the pump to cause it to operate at a stored partialised pre-brewing electrical power, so as to result in a time development of the flow rate of the brewing liquid supplied to the brewing chamber being initially substantially constant at an initial pre-brewing flow rate during filling of the brewing chamber and subsequently decreasing from the initial pre-brewing water flow rate to a final pre-brewing flow rate to cause the brewing chamber to become completely filled;
• brewing phase:
• closed-loop controlling the pump based on the flow rate of the brewing liquid measured by the flow meter so as to cause a stored target brewing flow rate to be reached and then maintained from an initial brewing flow rate.