Method and device for dynamically adjusting an operational voltage for an electric motor

摘要

Device and method for dynamically adjusting an operating voltage for an electric motor (9), which voltage is provided by a voltage source (1) formed in a modular manner, wherein modules (2-i) of the voltage source (1) formed in a modular manner are switched in dependence upon a rotational speed (n) of the electric motor (9) such that the overall degree of efficiency of the electric drive train is improved in a low rotational speed range of the electric motor (9), wherein the modules (2-i) of the voltage source (1) are switched by means of a switching network (3) which is composed of controllable power switches (5) and can be actuated by control signals which are generated by a switching controller (4) in dependence upon the rotational speed (n) of the electric motor (9).

主权项

1. A device for dynamically adjusting an operating voltage for an electric motor, the device comprising:
a voltage source formed in a modular manner and configured to provide the operating voltage; wherein modules of said voltage source formed in the modular manner are switched in dependence upon a rotational speed of said electric motor; wherein the modules of said voltage source are switched by means of a switching network which is composed of controllable power switches and can be actuated by control signals which are generated by a switching controller in dependence upon the rotational speed of said electric motor; wherein at least one rotational speed threshold is set between rotational speed ranges, at which the modules of said voltage source formed in the modular manner are switched in dependence upon the rotational speed of said electric motor; wherein the at least one rotational speed threshold is used as a switching threshold for changing from (1) an at least partial parallel connection of said modules of said voltage source to an at least partial series connection of said modules of said voltage source, or (2) the at least partial series connection of said modules of said voltage source to the at least partial parallel connection of said modules of said voltage source; and wherein said at least one rotational speed threshold is set such that the overall degree of efficiency of an electric drive train, which comprises said electric motor and a converter, is identical in the case of the at least partial parallel connection of said modules of said voltage source and the at least partial series connection of said modules of said voltage source, and is further set such that this at least one rotational speed threshold is below the maximum rotational speed of said electric motor possible with the corresponding at least partial parallel connection of said modules of said voltage source.