Device for determining the resistive torque of a rotating item of equipment, system for monitoring the operation of an electric motor and system for regulating the operating parameters of a ce

A device for determining the resistive torque of an item of equipment driven by an asynchronous electric motor operated by a control unit delivering to the motor an alternating voltage for controlling the rotational speed of the motor includes a measuring unit for measuring the rotational speed, a calculator for calculating the motor slip from the said rotational speed and the synchronous speed of the magnetic field generated by the power-supply voltage and a comparator for comparing the calculated value of slip and a set of predetermined slip values each corresponding to a resistive torque value, so that the resistive torque of the item of equipment can be determined.

If you were to search for Device for determining the resistive torque of a rotating item of equipment, system for monitoring the operation of an electric motor and system for regulating the operating parameters of a ce using relaxed search criteria, these patents would come up:

What is claimed is:

1. A system for monitoring the operation of a centrifuge, said system comprising an asynchronous electric motor and a control unit for supplying alternating current voltage tosaid motor so as to control the rotational speed of said motor, said control unit comprising:

a device for determining the resistive torque of a rotor of the centrifuge driven by said motor, said device comprising:

measuring means for measuring the rotational speed of said motor,

calculating means for calculating a characteristic representative of the slip of said motor, based on the rotational speed measured by said measuring means, so as to produce a calculated value of said characteristic, and

value comparing means associated with said calculating means for providing a comparison of said calculated value with a set of predetermined slip values each corresponding to a resistive torque value and for determining the resistive torque valueof the rotor of the centrifuge based on said comparison,

said control unit further comprising: storing means for storing a set of resistive torque values each corresponding to a particular type of rotor and each associated with a maximum allowed rotational speed permitted for the particular type ofrotor; and

means for comparing the resistive torque of the rotor of the centrifuge determined by said value comparing means with the resistive torque values stored in said storing means so as to determine the rotor type of the rotor of the centrifuge andthe associated maximum rotational speed thereof and for detecting an incompatibility between the maximum allowable rotational speed and a command to drive the rotor of the centrifuge at a rotational speed higher than the maximum allowable rotationalspeed for the rotor type of the rotor of the centrifuge.

2. A system for monitoring the operation of a centrifuge comprising an asynchronous electric motor operated by a control unit delivering to said motor an alternating power-supply voltage for controlling the rotational speed of the motor,

said control unit comprising a device for determining the resistance torque of a centrifuge rotor driven in rotation in association with the asynchronous electric motor, and said device comprising:

means for measuring the rotational speed of the motor;

calculating means for calculating a characteristic that represents the motor slip to produce a calculated value of said characteristic;

comparing means, associated with said calculating means, for comparing the calculated value of said characteristic with a stored set of predetermined slip values, each corresponding to a resistive torque value and for thereby determining theresistance torque on the centrifuge rotor,

said control unit further comprising storing means for storing a set of resistive torque values each corresponding to a type of rotor and each associated with a maximum allowable rotational speed permitted for the respective type of rotor and thecentrifuge, and

said comparing means comparing the resistive torque of the centrifuge rotor determined by said device with the resistive torque values stored in the storing means so as to determine the type of rotor and the associated allowable rotational speed,and detecting an incompatibility between the maximum allowable rotational speed and a command to drive the centrifuge rotor at a rotational speed higher than the associated maximum allowable rotational speed.

3. The system according to claim 2, wherein said calculating means comprises means for comparing the synchronous speed of the magnetic field of the motor with the measured rotational speed of the motor.

4. The system according to claim 2, wherein said characteristic is a characteristic that depends on temperature, and

wherein said system further includes means for measuring the air temperature around the rotor and for producing an output in accordance therewith,

said calculating means receiving said output and using said output in calculating said characteristic.

5. The system according to claim 2, wherein the control unit comprises limiting means for limiting the rotational speed of the rotor to a maximum permitted value of the rotational speed of the rotor.

6. A system for controlling operating parameters of a centrifuge comprising an asynchronous electric motor operated by a control unit delivering to the motor a power-supply voltage for controlling the rotational speed of the motor so as tocontrol rotational driving of a centrifuge rotor arranged in a chamber of the centrifuge, and regulating means for regulating operating parameters of the centrifuge,

said control unit comprising a device for determining the resistive torque of the centrifuge rotor driven in rotation in association with the asynchronous electric motor, and said device comprising:

means for measuring the rotational speed of the motor;

calculating means for calculating a characteristic that represents the motor slip to produce a calculated value of said characteristic;

comparing means, associated with said calculating means, for comparing the calculated value of said characteristic with a stored set of predetermined slip values, each corresponding to a resistive torque value, and for thereby determining theresistive torque of the centrifuge rotor,

said control unit further comprising:

storing means for storing a set of resistive torque values each corresponding to a type of rotor and each associated with a set of operation regulating parameters for regulating the operation of the centrifuge corresponding to the type of rotor,and

said comparing means comparing the resistive torque of the centrifuge rotor determined by said device with the set of resistive torque values stored in the storing means so as to determine the type of rotor with which the centrifuge is equippedand delivering to the regulating means the values of the operation regulating parameters corresponding to the centrifuge rotor.