| CPC H02P 6/16 (2013.01) [H02K 11/215 (2016.01); A47J 31/36 (2013.01)] | 12 Claims |

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1. A machine (70) for preparing coffee beverages comprising an infusion unit (71) provided with an infusion chamber (73), a direct current motor (50) connected to said infusion unit (71) and with a control circuit (10) for said motor (50), wherein said control circuit (10) comprises:
a power supply circuit (14) which connects said motor (50) to an electric power supply grid (60) configured to supply an alternating supply voltage (Vin);
a detection device (12) for detecting the instant of the zero-crossing of said supply voltage (Vin) of the electricity grid;
a switch device (11) connected between said electric power supply grid (60) and said motor (50), which can be selectively activated to allow or prevent the passage of an electric current between said electric power supply grid (60) and said motor (50);
and a control and command unit (13) configured to selectively activate said switch device (11) to power the motor (50) by means of the positive half-waves (Vin1) of said supply voltage (Vin) to rotate it in one sense, and by means of the negative half-waves (Vin2) to rotate it in the opposite sense, wherein said control and command unit (13) is configured to receive a detection signal (Sz) of said instant of the zero-crossing of said supply voltage (Vin) and supply an activation command signal (ST1, ST2) for said switch device (11) with a delay time (Td1, Td2) with respect to said crossing instant detected, so that said switch device (11) enters into conduction when the value of the current (Im) applied to the motor (50) is near zero.
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