Apparatus and method for measuring current
AssigneeSiemens Aktiengesellschaft
InventorRobert Carter
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Abstract
The present invention discloses apparatus and a method for measuring the motor current in an AC drive system in which the DC link current in a voltage source inverter (20) is separated into a transistor current, and a diode current, and then measured separately with shunts (22, 24). This results in two independent non-isolated current measurements and allows for a more accurate calculation of the magnitude of the motor current. (FIG. 2)
Claims27
An apparatus for determining current flowing between an inverter and a load, said apparatus comprising:
- a first current measuring device;
- a second current measuring device, said first and second current measuring devices being arranged on a DC input side of the inverter, such that said first current measuring device measures a first current flowing at said input side of said inverter and said second current measuring device measures a second current flowing at said input side of said inverter;
- and
- a processor which calculates a magnitude of load current which flows between the inverter and the load, based on said first and second currents measured by said first and second current measuring devices.
A method of determining load current flowing between an inverter and a load, said method comprising:
- measuring a first current flowing at a DC input side of said inverter;
- measuring a second current flowing at said DC input side of said inverter;
- and
- calculating load current flowing between an output side of said inverter and said load, based upon said first and second currents.
Dependencies are inferred from the claim text.