US 6,087,800 A · Integrated soft starter for electric motor

Abstract

A solid state motor starter, commonly referred to as a soft starter, is constructed in a manner to be easily manufacturable while at the same time combining all the required components in a relatively small package. A solid state power switch is clamped between a pair of bus bars in an offset manner to accommodate a discrete switching relay mounted in an inverted manner between the line input and the bus bar in communication with the load outputs. When in a motor run node, current is shunted away from the solid state power switching device and through the switching relay, a substantially linear current path is achieved to reduce power loss and heat buildup. The arrangement allows for a heat sink mounted to one of the bus bars with adequate spacing between the heat sink and the discrete relay for insertion of a cooling fan. Current sensing is achieved with a Hall effect sensor mounted to the bus bar in a small current sensing region that is created by having a pair of slots in the bus bar to direct current. A pair of magnetic pins extend perpendicular from the bus bar to create the magnetic flux for the Hall effect/sensor to sense current flow through the current sensing region. The Hall effect sensor circuit board also contains a thermistor which is mounted with adequate insulation yet in thermal communication with the bus bar.

Claims27

Dependent claims

A solid state motor starter comprising:

a first electrically conducting bus bar adapted to receive an external current carrying conductor from a power source at an input end;
a second electrically conducting bus bar adapted to receive an external current carrying conductor connectable to a motor at an output end of the motor starter;
a pair of solid state power switching devices clamped between the first and second electrically conducting bus bars;
and
a discrete electromagnetic switching relay having an electrical input and an electrical output forming a bypass current path, the electrical input connectable to the external current carrying conductor from the power source through the first electrically conducting bus bar, and the electrical output of the switching relay connectable to the output end of the motor starter, the discrete electromagnetic switching relay mounted such that the bypass current path is in linear relation with the second electrically conducting bus bar, thereby providing a linear current path through the solid state motor starter when the discrete electromagnetic switching relay is switched to relay power from the power source to the motor.

2 more elements

A solid state motor starter having two distinct current paths therein and constructed compactly comprising:

a first current path structure defined by a power supply input connectable to a first bus bar, the first bus bar in electrical connection with a pair of solid state power switches for completing electrical connection with a second bus bar when at least one of the solid state power switches is switched to an ON state to ramp-up power to a motor connectable to the second bus bar during motor start-up and to ramp-down power to the motor during motor shut-down;
and
a second current path structure operable during a motor run mode and defined by the power supply input connectable to an input of an inverted electromagnetic relay through the first bus bar, the inverted electromagnetic relay switchable between a current conducting mode and a current non-conducting mode, when the electromagnetic relay is in a current conducting mode and the solid state motor starter is therefore in the motor run mode, the second current path is further defined by an electrical connection between an output of the electromagnetic relay and the first bus bar connectable to the motor, wherein the second current path is a substantially linear current path to reduce power loss and minimize hear build up during the motor run mode.

Dependencies are inferred from the claim text.

Integrated soft starter for electric motor

Life of this patent

Integrated soft starter for electric motor

Life of this patent

Abstract

Claims27