MAC DIVISION

Asynchronous vector motors

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INVERTER DRIVE: WHICH MOTOR TO USE WITH?INVERTER DRIVE: WHICH MOTOR TO USE WITH?

Are you planning to run a marathon in high-heeled shoes?

Then, why are you using an standard asynchronous motor in your variable speed application?

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STANDARD MOTOR vs VECTOR MOTORSTANDARD MOTOR vs VECTOR MOTOR

Design priorities:

PARAMETER STANDARD MOTOR VECTOR MOTOR

Operation Directly from the mains Inverter duty

V/ F ratio Fixed (400V/ 50Hz in Europe)Variable, depending on the applicationThe inverter allows different V/ F ratios

Power factorParameter to be maximised

It reduces the reactive power consumptionIt's not a priority

The inverter corrects the reactive power consumption

Starting peak current Parameter to be minimised

It will determine the protectionsThere's no starting peak values due Inverter duty

Starting torque To be maximised Nominal Torque from 0 rpm's

InertiaNot important

It's not designed to be used in variable speed To be minimised in order to have the best dynamic

performances

Peak Torque -To be maximised

To match the Inverter current limits

Cooling system Self cooling systemActive Fan cooled

The best performances from 0 rpm's

Constant Power RangeNot important

It's not designed to be used in variable speed To be maximised

Wide working zone in field weakening mode

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CONSTRUCTIVE DETAILSCONSTRUCTIVE DETAILS

Active Fan cooling system

Second shaft for encoder fitting

Integrated encoder connector

Reinforced materials and vacuum impregnation

Low inertia Rotor

Integrated PTC for thermal winding protection

Low losses laminated square frame

Parking brake option

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MOTOR PERFORMANCES: STANDARD vs VECTORMOTOR PERFORMANCES: STANDARD vs VECTOR

NominalOverload

125Hz

Vector MAC Q .

50

Nm

NominalOverload

40 70

Standard

100 %

160 %

200 %

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TYPICAL PROBLEMS USING STANDARD MOTORS FOR INVERTER DUTYTYPICAL PROBLEMS USING STANDARD MOTORS FOR INVERTER DUTY

Motor warming at low speed operation Standard: Insufficient motor cooling working at low speeds due a self cooling design.

Vector: Perfect motor cooling at any speeds thanks to its active fan cooling system.

Low Torque performances working beyond the nominal speed Standard: Not designed to work beyond the nominal speed: very limited constant power work.

Vector: Wide constant power working area. Very useful in winding applications

Poor acceleration response: Problems in dynamic applications Standard: High rotor inertia values. Very poor dynamic performances.

Vector: Very good dynamic performances thanks to the optimisation of the rotor design (Ø/length ratio)

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High maintenance costs: Limited expected life time Standard: Fast degradation of winding and isolating materials due the high frequency voltage transitions.

Vector: Long life time thanks to the reinforced materials and vacuum impregnation.

Additional motor modifying costs Standard: Require additional motor manipulation: not prepared to fit a feedback device for close loop

operation (encoders, resolvers...), neither active fan cooling system for low speed operation.

Vector: Integrated active fan cooling system. Prepared to fit any feedback device.

Higher Current consumption and inverter size Standard: It’s not possible to match the motor and application speed performances. There’s only two available

winding codes: Start and delta connection.

Vector: Each motor can be manufactured with an specific winding code in order to exactly adjust de motor current consumption to the inverter current limits.

TYPICAL PROBLEMS USING STANDARD MOTORS FOR INVERTER DUTYTYPICAL PROBLEMS USING STANDARD MOTORS FOR INVERTER DUTY

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PRICE: STANDARD MOTOR VS VECTOR MOTORPRICE: STANDARD MOTOR VS VECTOR MOTOR Although the vector motors are more expensive than standard

asynchronous motors, this price increment is widely compensated by their technical advantages.

In order to perform a right economical comparison between this two motor types, it will be necessary to take into account the total cost of each COMPLETE solution:

Additional modifying costs: Feedback and active fan installation.

Motor oversizing: Due the poor performances of the standard motors working with inverter duty.

Repair costs: Material degradation due to inverter duty work.

Inverter price: Vector motors can improve the inverter sizing through the right choice of the winding code

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SECTORS & APPLICATIONSSECTORS & APPLICATIONS

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CONCLUSIONSCONCLUSIONS Standard asynchronous motors are suitable for fixed speed applications and mains supply, vector motors are suitable for inverter duty and variable speed applications.

Main advantages of asynchronous vector motors:

No warming problems with low speed operation. Wide constant power working range. High dynamic response: low inertia. High overload capacity. Longer expected life time: repair & maintenance cost savings. No need of motor modifications: Integrated encoder and active fan. Reduction of inverter size: customised windings Dimension savings: high power density