US 6,583,682 B1 · Method of reducing conducted EMI in motor drive applications

Abstract

Conductive EMI in motor drive circuits is reduced by interposing inductors in the ground line. The common mode current enters the motor drive circuit through the two supply leads and leaves the system through the ground lead. The ground current typically is very high frequency but very low in rms amperage. Interposing an induction (low current, very high L) in the ground line advantageously reduces EMI. The inventive method reduces.or eliminates the need for filtering capacitors across the rectifier of the motor drive circuit. In addition, the inventive method minimizes the common mode choke to merely a wraparound ferrite core over the input wires. EMI emissions are reduced further by sandwiching ground traces along with power traces and connecting to.the heat sink with the shortest possible route. This reduces the ground loop area, which consequently reduces emissions.

Claims8

Dependent claims

A motor drive circuit having reduced EMI, comprising:

an inverter having a pair of supply leads and being connectable to a motor for driving the motor;
an earth ground for providing a common reference for the motor drive circuit;
a heat sink thermally coupled to the inverter and having a heat sink ground separate from the earth ground;
and
an inductor connected in series between the heat sink ground and the earth ground, whereby high frequency common mode current conducted in the motor drive circuit is reduced.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application

09/553,757Filed 21 Apr 2000 · us provisional application

Priority

22 Apr 1999

Granted

24 Jun 2003

Term ends

Not estimatedThe source records don’t support an estimate.

Classification6 codes

H02M 1/44
Details of apparatus for conversion: circuits or arrangements for compensating for electromagnetic interference in converters or inverters
H02M 1/12
Details of apparatus for conversion: arrangements for reducing harmonics from AC input or output
H02M 5/45
Using devices of a thyratron or thyristor type requiring extinguishing means: using semiconductor devices only
H02M 7/003
Conversion of AC power input into DC power output; Conversion of DC power input into AC power output: constructional details, e.g. physical…

Method of reducing conducted EMI in motor drive applications

Life of this patent

Method of reducing conducted EMI in motor drive applications

Life of this patent

Abstract

Claims8