Pump speed controlling method and apparatus, a computer program and a computer readable medium having stored thereon the computer program applied thereby and a pump

A method for controlling a speed of a Variable Speed Drive, (VSD) vacuum pump employed in a cyclic application, comprising:

• controlling the pump to operate in repeated cycles, each cycle comprising a pump down phase and a holding phase, wherein each cycle starts at a time point when a rise in an inlet pressure of the pump reaches a preset threshold and the time between two consecutive cycle starts is a cycle time;
• determining, during a present cycle, a start of a next cycle, wherein the present cycle directly precedes the next cycle;
• estimating pre-speeding time of the next cycle based on an estimation of the pre-speeding time determined for the present cycle and an observation of the pre-speeding time of the present cycle, each pre-speeding time referring to a length of time since a respective start of a respective cycle until a time point in the holding phase of the respective cycle when the pump is controlled to speed up;
• and
• controlling the pump to speed up to a maximum speed during the holding phase of the next cycle at the end of the estimate of the pre-speeding time of the next cycle before the start of a cycle after the next cycle such that at the start of the cycle after the next cycle full pump capacity is available.