Patent ID: 6940247

Claim:
A drive control for an electric drive having a high level of control dynamics in the form of a meshed control structure comprising a rotational speed control loop, a current control loop arranged inside said rotational speed control loop, the rotational speed control loop comprising a controller with a proportional component and integral component and a phase saving lowpass filter selected from the group consisting of a PDT 2 element and a Cauer filter for suppressing resonances in the controlled system, said filter tuned to the resonances to be suppressed with regard to frequency range and amplitude reduction, wherein said filter filters a range of frequencies wider than conventional lowpass filters, and with a substantially smaller phase drop; and wherein the PDT 2 element utilizes the following second order differential equation: u k =V F *( e k +a 1 e k-1 +a 0 e k-2 )− u k-1 b 1 −u k-2 b 0 , where u k is the filter output in the computing cycle k, and e k is the filter input in the computing cycle k; further wherein the Cauer filter is selected from the group consisting of a second order and an eighth order, and wherein as to the later utilizes the eighth order differential equation: u k =a 0 u k-1 +a 1 u k-2 + . . . +a 7 u k-7 +b 0 e k +b 1 e k-1 + . . . +b 8 e k-8 , where u k is the filter output in the computing cycle k, and e k is the filter input in the computing cycle k.