A method for controlling a gas flow of a pump for high flow rates at a low average flow rate by changing the gas pressure inside a cavity in said pump. The method includes decreasing the gas pressure in said cavity during a first predetermined time period, increasing the gas pressure in said cavity during a second predetermined time period, and stopping the active change of gas pressure during at least a third predetermined time period. Additionally, a pump assembly for high flow rates operated at a low average flow rate is disclosed that includes a number of pumps, a pump motor with a number of stator windings adapted to drive said pumps, and a control unit adapted to control said pump motor. In one embodiment the number of pumps is equal to said number of stator windings. The motor can momentarily increase its force on the pumps.