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MAC DIVISION
Asynchronous vector motors
Reservados todos los derechos por Vascat, S.A.
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?
Reservados todos los derechos por Vascat, S.A.
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
Reservados todos los derechos por Vascat, S.A.
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
Reservados todos los derechos por Vascat, S.A.
MOTOR PERFORMANCES: STANDARD vs VECTORMOTOR PERFORMANCES: STANDARD vs VECTOR
NominalOverload
125Hz
Vector MAC Q .
50
Nm
NominalOverload
40 70
Standard
100 %
160 %
200 %
Reservados todos los derechos por Vascat, S.A.
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)
Reservados todos los derechos por Vascat, S.A.
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
Reservados todos los derechos por Vascat, S.A.
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
Reservados todos los derechos por Vascat, S.A.
SECTORS & APPLICATIONSSECTORS & APPLICATIONS
Reservados todos los derechos por Vascat, S.A.
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