Beverage preparation device with pump and method for controlling the pump

1. A beverage preparation device designed for preparing a beverage upon injection of fluid into an ingredients-containing cartridge, the beverage preparation device comprising:

an electrically operated pump coupled between a fluid inlet and a fluid outlet for pumping the fluid from the fluid inlet to the fluid outlet;

a processing unit for the electrically operated pump configured to control an operation of the electrically operated pump in response to an electrical energy, the electrical energy having a wave form;

the processing unit is configured to determine respective selected half cycles in which the electrically operated pump is energized based on:

a target ratio, wherein the target ratio is a ratio between a target flow rate and a predefined maximum flow rate of the electrically operated pump, and

calculation of an activation ratio, wherein the activation ratio is a ratio between a number of past half cycles for which the electrically operated pump was energized to a number of overall half cycles during a respective beverage preparation process.

2. The beverage preparation device according to claim 1 , wherein the processing unit of the beverage preparation device is configured to constantly compare values of the target ratio and the activation ratio.

3. The beverage preparation device according to claim 1 , wherein the processing unit is configured to individually calculate for each of the respective half cycles of the wave form of the electrical energy whether the electrically operated pump is to be energized throughout the respective half cycle or not.

4. The beverage preparation device according to claim 1 , wherein the electrically operated pump is configured to be energized by the processing unit for the respective half cycle when the activation ratio is lower than the target ratio.

5. The beverage preparation device according to claim 1 , wherein the beverage preparation device is void of a flow meter for detecting an actual flow rate in a fluid circuit of the beverage preparation device.

6. The beverage preparation device according to claim 1 , wherein the processing unit of the beverage preparation device is void of a burst fire control or a phase angle control.

7. The beverage preparation device according to claim 1 , wherein the wave form of the electrical energy is a sinusoidal alternating current.

8. The beverage preparation device according to claim 1 , wherein the beverage preparation device comprises a component configured for identifying the ingredients-containing cartridge inserted in the beverage preparation device and enabling the processing unit to define the target flow rate and/or an amount of the fluid injected into the ingredients-containing cartridge during the beverage preparation process.

9. The beverage preparation device according to claim 1 , wherein the electrically operated pump comprises a spring-loaded linear pumping member.

10. The beverage preparation device according to claim 1 , wherein the predefined maximum flow rate of the electrically operated pump is obtainable when energizing the electrically operated pump in each of the respective half cycles.

11. A method for controlling an electrically operated pump for pumping a fluid from a fluid inlet to a fluid outlet of a beverage preparation device, the method comprising:

generating a control signal for operating the electrically operated pump from an electrical energy having a wave form;

providing the control signal to energize the electrically operated pump only throughout selected half cycles of the wave form of the electrical energy;

wherein the respective selected half cycles in which the electrically operated pump is energized are determined:

based on a target ratio, wherein the target flow rate is a ratio between a target flow rate and a predefined maximum flow rate of the electrically operated pump, and

based on calculation of an activation ratio, wherein the activation ratio is a ratio between a number of past half cycles for which the electrically operated pump was energized to a number of overall half cycles during a respective beverage preparation process.

12. The method according to claim 11 , wherein the method comprises constantly comparing values of the target ratio and the activation ratio and determining whether the electrically operated pump is to be energized throughout the respective half cycle or not.

13. The method according to claim 11 , comprising providing the control signal to energize the electrically operated pump throughout the respective half cycle of the wave form of the electrical energy when the activation ratio is lower than the target ratio.

14. The method according to claim 11 , comprising:

setting the target ratio for the beverage preparation device based on a ratio of a desired target flow rate and the predefined maximum flow rate of the pump,

setting an initial integer value of counting variables A and B to “1”,

comparing for each respective half cycle of the wave form of the electrical energy a ratio of A/B to the target ratio, and:

if the ratio A/B is less than or equal to the target ratio, energizing the electrically operated pump throughout the respective half cycle and increasing the integer value of counting variable A by “+1”; and

if the ratio A/B is greater than the target ratio, not energizing the electrically operated pump throughout the respective half cycle,

increasing the integer value of counting variable B by “+1” after determination of the ratio A/B for each of the respective half cycles.

15. The method according to claim 11 , wherein when at one step (B max ) the beverage preparation device determines that, for the corresponding half cycle (n) of the wave form of the electrical energy, the difference between a ratio of A/B max and the target ratio is less than a predetermined percentage, each of the initial integer values of counting variables A and B are reset to 1.