Motor assembly and hoist drive

Patent metadata

Field	Value
Publication number	US-2016264382-A1
Application number	US-201415032560-A
Country	US
Kind code	A1
Filing date	Dec 1, 2014
Priority date	Dec 4, 2013
Publication date	Sep 15, 2016
Grant date	—

Abstract

A motor assembly includes a three-phase asynchronous machine equipped with three stator phases, a capacitor assembly to establish self-excited generator operation of the asynchronous machine, a load resistor assembly to establish resistive load for self-excited generator operation of the asynchronous machine, and a load resistor switch which is arranged to connect the load resistor assembly to the stator phases. The load resistor assembly is asymmetrical.

First claim

1 . A motor assembly comprising:
a three-phase asynchronous machine equipped with three stator phases; a capacitor assembly; a capacitor switch for symmetrically connecting the capacitor assembly to all three stator phases to establish self-excited generator operation of the asynchronous machine; a load resistor assembly to establish resistive load for self-excited generator operation of the asynchronous machine; and a load resistor switch arranged to connect the load resistor assembly to the stator phases, wherein the load resistor assembly is asymmetrical.

2 . The motor assembly as claimed in claim 1 , wherein the load resistor assembly comprises one load resistor, only, which is arranged to be connected between two stator phases of the asynchronous machine during self-excited generator operation of the asynchronous machine.

3 . The motor assembly as claimed in claim 2 , wherein the load resistor switch comprises a resistor switch arranged to connect the load resistor between two stator phases of the asynchronous machine, based on commands by an operator.

4 . The motor assembly as claimed in claim 1 , wherein the load resistor assembly comprises exactly two load resistors, the first of which is arranged to be connected between a first pair of stator phases of the asynchronous machine during self-excited generator operation of the asynchronous machine, and the second of which is arranged to be connected between a second pair of stator phases of the asynchronous machine during self-excited generator operation of the asynchronous machine, the second pair of stator phases being different from the first pair of stator phases.

5 . The motor assembly as claimed in claim 1 , wherein the load resistor assembly comprises three load resistors each of which is arranged to be connected between two stator phases of the asynchronous machine during self-excited generator operation of the asynchronous machine, one of the three load resistors having a substantially different resistance from another second resistor of the three load resistors.

6 . The motor assembly as claimed in claim 1 , wherein the load resistor switch comprises at least one voltage-controlled switch, each voltage-controlled switch being operationally connected to a corresponding stator phase so that the voltage-controlled switch closes in response to the presence of a voltage of a predetermined level in the corresponding stator phase.

7 . The motor assembly as claimed in claim 6 , wherein each of the voltage-controlled switches is connected in series with the resistor switch controllable by an operator.

8 . The motor assembly as claimed in claim 1 , wherein the capacitor assembly comprises three excitation capacitors, and the load resistor assembly comprises one load resistor, only, which is connected in parallel with one excitation capacitor, and the load resistor switch and the capacitor switch are integrated.

9 . The motor assembly as claimed in claim 1 , wherein the load resistor switch is an intelligent load resistor switch arranged to connect the load resistor assembly to the stator phases in a voltage-controlled manner in a situation where an emergency lowering of a load has been activated by an operator or automatic operation.

10 . The motor assembly as claimed in claim 9 , wherein the intelligent load resistor switch comprises at least one intelligent resistor switch arranged to transfer to a standby state in response to an operator's command to initiate an emergency load lowering, in which standby state the at least one intelligent resistor switch is monitoring whether a voltage of a predetermined level is present in the stator phases, and closes in response to a detected presence of the voltage of the predetermined level in the stator phases.

11 . The motor assembly as claimed in claim 1 , wherein the capacitor assembly comprises three excitation capacitors in such a manner that in said symmetric connection three excitation capacitors are connected to the stator phases by a delta or star connection.

12 . The motor assembly as claimed in claim 1 , wherein the load resistor switch and the capacitor switch are arranged to be controlled by the same signal.

13 . A hoist drive comprising:
a rope; a hoisting member attached to the rope; and a motor assembly operationally connected to the rope to lift a load by means of the hoisting member, the motor assembly comprising: a three-phase asynchronous machine equipped with three stator phases; a capacitor assembly to establish self-excited generator operation of the asynchronous machine; and a load resistor assembly to establish resistive load for self-excited generator operation of the asynchronous machine, wherein the load resistor assembly is asymmetrical.

Assignees

• Konecranes Global Corp

Inventors

• Repo Anna-Kaisa
• Uusiniitty Toni
• Vepsäläinen Jarmo
• Hietanen Lauri
• Haalahti Marko

Classifications

• B66D5/30

  electrical · CPC title

• B66C13/26 Primary

  by AC motors · CPC title

• B66C13/30

  Circuits for braking, traversing, or slewing motors · CPC title

• B66C13/28 Primary

  utilising regenerative braking for controlling descent of heavy loads and having means for preventing rotation of motor in the hoisting direction when load is released · CPC title

• H02K17/30

  Structural association of asynchronous induction motors with auxiliary electric devices influencing the characteristics of the motor or controlling the motor, e.g. with impedances or switches · CPC title