AC electric drives of АТК series
for wound rotor asynchronous motors
Complete AC electric drives on the basis of “asynchronous-thyristor cascade” system ATК are a new stage in the development of the structure of wound-rotor slip recovery system (asynchronous-valve cascade) (АВК) that is widely used in controlled-velocity electric drives with wound rotor asynchronous motors.
Regulating qualities of АТК electric drive can be compared to those of a DC electric drive. The range of rotational speed adjustment is no worse than 20:1 without a velocity transducer and no worse than 40:1 with a velocity (rotational frequency) transducer at a motor shaft.
Energy saving in processing installations on the basis of АТК electric drives can reach 15-30% compared to application of rotor stations.
By functional and cost characteristics АТК electric drives have no alternatives in modernization of functioning processing facilities that is carried out without replacement of customer's wound rotor asynchronous motors.
The equipment of complete electric drive АТК540/1140/1250-211УХЛ4 for a mine hoist МПБ 5-2,5-2,5 of double-skip hoisting with two motors АКН2-19-33-20УХЛ4
Structure and operation
on the example of a double-motor electric drive АТК540/1140/1250-211УХЛ4 of a mine hoist МПБ 5-2,5-2,5.
The simplified diagram of the electric drive is given below with the following indications:
ВВ1… ВВ3 – high-voltage switches;
Reverser 1, reverser 2 – high-voltage contactor reversers;
М1, М2 – wound rotor asynchronous motors;
ШКВ – high-voltage switching cabinet;
ШКН1, ШКН2 – low-voltage switching cabinet;
ШРП – cabinets of rotor converters;
ШСП – cabinet of network converter (inverter);
МПСУ – microprocessor control system;
Lдр1… Lдр4 – set of smoothing reactors;
TV – step-up transformer;
ТГ (ДВИ) – tacho-generator or pulse rotation transducer (ДВИ or analog)
Advantages of АТК series electric drives
- АТК drive provides bidirectionality of energy current in the circuit “supply network – motor – rotor circuit (cascade circuit) – circuit of energy recovery to supply network” unlike traditional АВК, and that allows performing motor braking without application of additional dynamic braking devices;
- The series of АТК electric drives provides control over asynchronous phase motors with rotor voltages from 400 V up to 1 500 V at rotor currents from 200 A up to 1 600 A. It is possible to extend the existing series and deliver multi-motor АТК electric drives (for conveyors, for example) on a special order.
- The power part of АТК is implemented on standard single-operation thyristors and has a relatively simple cascade circuit with high overload capacity.
- The structure of thyristor cabinets of АТК electric drives is to a great extent unified with the structure of DC electric drives of ЭКТЦ (EKTC) type, and that allows reducing operational expenses and raising the maintenance quality of products on facilities with different processing equipment.
Cabinet ШРП2х630/1400 (two thyristor bridges 630 А, 1 400 V) with МПСУ system
- A set of reactor-transformer and additional power equipment is produced to order taking into account the requirements for operational voltage of insulation of a particular product depending on motors parameters.
A set of switching equipment provides flexible coupling of the product with Customer's equipment with simultaneous raise of facilities exploitation reliability due to the transfer of present rotor stations of phase motors control to the reserve.
High-voltage switching cabinet ШКВ10/400 (10 kV, 400 А)
Low-voltage switching cabinet ШКН1,14/630-03
(1 140 V, 630 А– vacuum contactors)
Cabinet of disconnecting switches ШР (1 200 V, 1 000 А – equipment for powerful electric drives, it supplements a setof switching equipment of ШКН cabinets)
- МПСУ implements dual-circuit system of regulation of motor rotation frequency with a slave current (torque) controller. Thereby an independent control over a motor velocity and torque is provideddue to the regulation of the rotor current (network converter current).
- The microprocessor control system (МПСУ) of АТК electric drives is implemented in the form of unified program-functional units, the most part of which is applied in МПСУ of DC electric drives. МПСУ includes a system of data visualization and archiving.
- Standard interfaces provide connection of МПСУ with automatic process control systems (an automatic control system of the upper level).