Kontrola Chopper ji Bo Motor DC bê Bistînên Berjariya Yekîyan

Kûrter yek cihaz e ku bişdarî vêjî yên direct current (DC) bêtgeha dîrect current (DC) ya guhertin da. Di çavkaniyên kûrter de, wergerên wekî Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs), Insulated-Gate Bipolar Transistors (IGBTs), wergerên nîrvan, Gate-Turn-Off Thyristors (GTOs), û Integrated Gate-Commutated Thyristors (IGCTs) pêşbend in. Ew wergerên ji bo amadekirina kûrterên bikar anîn da ku hewl dikin vegereya jorî yên gate control signal di navbera inputsên nîrvan de û nehat biben malpera commutation circuit, ewamandî û praktîk li ser kêmên kûrter.

Kûrteran jêr freqencên bilind dixebit. Li gorîna operasyonê ya freqencê ya bilind, performansa motori piştguh kir û ripplên vêjî û nîrvan hatine kam kir û conduction ê discontiniuous hatine rast kir. Yek ji zafiyên herî nîşankirî ya kontrolê ya kûrter heke wekî regenerative braking piştguh kir lê tevahî rotaçyonê ya bi qadê re. Ev wateyê derbasdare ye ku divê sisteman drive bi vêjî DC yên fixed-to-low hatine amade kir, ku hewce bike energy recovery ê şeftîn leser operasyonên braking.

Kontrolê Motori

Wêne li vir ilustrasyonê ya motori DC separately-excited yên ku bi chopper transistor kontrol kir. Transistor Tr di demekan de piştguh kir û ji bo demekan Ton li navgîre were girî. Formên wave ê terminal voltage û armature current ya motori taybetand li vir wêney. Wanê transistor a li vir bie, terminal voltage ya motori V e, û operasyonê ya motori wek hev bi vê rêzeyî dixwestin:

Li vir vê demekan, armature current ji ia1 ji bo ia2 girî. Ev fase li vir duty interval name kir, ji ber ku motor bi xebetî bi source yên nîrvan werdigirt. Girdestina direkta energy nîrvan ji source ji bo motor girî, ji bo werdigirtina torque mekanîk û rotaçyon.

Ji ber vê demekan (t = ton), transistor Tr veqet kir. Pêşinde, armature current di navgîra diode Df de freewheel kir. Wanê, terminal voltage ya motori ji zero girî li navgîra ton≤t≤T. Ev navgîra li vir freewheeling interval name kir. Ji bo vê fase, energy ê maghnetik û induktance ê motori di navgîra freewheeling diode de girt. Operasyonê ya motori li vir vê navgîra dibe analiz kir û tefsir kir bi serkirina electrical û magnetic ê componentan.

Armature current ji ia2 ji bo ia1 girî di vê navgîrede. Herdemîna duty interval ton ji chopper period T duty cycle name kir.

Regenerative Braking

Wêne li vir ilustrasyonê ya chopper yên ku bi regenerative braking operasyon amade kir. Transistor Tr di demekan de piştguh kir û ji bo demekan Ton li navgîre were girî. Li vir formên wave ê terminal voltage va û armature current ia bi continuous conduction conditions taybetand. Ji bo zêdekirina inductance value La, inductor external bi serkirina circuit hatine amade kir.

Ji ber vê demekan, armature current ia ji ia1 ji bo ia2 girî. Vê girîkirina current ji ber storage temporary ê energy nîrvan di inductor û magnetic field ê motor de, ji bo stage setting ê energy conversion process ê characteristic of regenerative braking.

Ji ber vê demekan, motor bi regenerative braking mode operate kir, ji bo generator, mechanical energy bi electrical energy convert kir. Yek parça electrical energy ji bo zêdekirina magnetic energy stored within the inductance of the armature circuit contribute kir. Li vir vê demekan, electrical energy remaining dissipated as heat within the armature windings û transistors, ji ber resistance inherent ê wan componentan.

Ji ber vê demekan, armature current di navgîra diode D û power source V de ji ia2 ji bo ia1 girî. Li vir vê proces, electromagnetic energy stored in the circuit û energy generated by the machine fed back to the power source. Navgîra ji 0 ji bo ton energy storage interval name kir, ji ber ku energy accumulates in the system. Wanê, navgîra ji ton ji bo T duty interval name kir, ji ber ku energy transfer û system operation occur.

Motoring and Braking Operation Control

Ji bo motoring operation, transistor Tr1 regulate kir bi power supply to the motor, enabling it to rotate forward. Wanê, ji bo braking operation, transistor Tr2 takes over control. Transition of control from Tr1 to Tr2 seamlessly switches the system's operation from motoring to braking, and reversing this control transfer shifts it back to the motoring state. This precise control mechanism ensures efficient and reliable operation of the electrical drive system under different working conditions.

Dynamic Control

Dynamic braking circuit, along with its corresponding waveform, is depicted in the figure below. In the time interval from 0 to Ton, the armature current ia steadily rises from ia1 to ia2. During this phase, a portion of the electrical energy is stored in the inductance, serving as a reservoir for subsequent operations. Simultaneously, the remaining energy is dissipated as heat within the armature resistance Ra and the transistor TR, a necessary consequence of the electrical resistance present in these components.

During the time interval Ton ≤ t ≤ T the armature current ia drops from ia2 to ia1. In this phase, both the energy generated by the motor and the energy stored in the inductances are dissipated across the braking resistance RB, the armature resistance Ra, and the diode D. The transistor Tr plays a pivotal role in regulating the amount of energy dissipated in RB. By precisely controlling the operation of Tr, one can effectively modulate the power dissipated in RB, thereby influencing the overall braking performance and the effective value of the dissipated energy. This control mechanism allows for fine-tuning of the dynamic braking process, ensuring optimal energy management and system stability.