Farkokin Soft Starter da VFD (Variable Frequency Drive)

Akwai farkon kayan kwaikwayar daɗi (VFDs) da soft starters su ne kalmomin daɗi mai fadada mota, amma aiki da suka shafi semiconductors yana ba da wasu hanyoyin. Idan haka, wadannan suke taimakawa da fadada da kafin mutumta cikin motoci, suna da farko daɗi a tsarin aiki, aiki da keɓa da na ƙasashen aiki.

VFDs suke taimakawa da gudanar da voltage da frequency don kontrola sako motoci daɗi, zai iya iya daidai da aiki a ƙasashen abubuwan da suka shiga. Amma soft starters suna yi amfani da ramping da voltage don hada inrush current a lokacin fadada bayan ya fara, bane ba su iya kontrola sako a baya ba. Wannan farkon daɗi na nuna aikinsu: VFDs suke taimakawa a ƙasashen abubuwan da ke so kuɗi, amma soft starters suke bayar da aiki daɗi da take daidaita a fadada waɗanda suka shiga motoci.

Idan za a duba farkon daɗi daga VFDs zuwa soft starters, ita ce muhimmanci a bayyana mazaunin motor starter.

Motor Starter

Motor starter shine babban wurin da aka haɗa da shi don fadada da kafin mutumta cikin induction motor daidai. A lokacin fadada, induction motor yana jin inrush current daɗi—kusan 8 karamin daɗin da aka rara—saboda hasukan winding resistance. Wannan surge zai iya ƙasa internal windings, kuma ƙare daɗi da motoci ko kuma ƙare burnout.

Motor starters suke haɗe wannan riski ta hanyar ƙara starting current, don haka suke taimakawa da motoci daga mechanical stress (misali, jerks) da electrical damage. Suna taimakawa da safe shutdowns, da kuma suke ƙara built-in protection daɗi low voltage da overcurrent—don haka suke zama abubuwan da ake buƙata don reliable motor operation.

Soft Starter

Soft starter shine specialized motor starter wanda yake ƙara inrush current ta hanyar ƙara voltage da aka bayar da motoci. Yana amfani da semiconductor thyristors don kontrola voltage:

• Thyristor Configuration: Pairs of back-to-back thyristors manage current flow in both directions.

• Three-Phase Systems: Require 6 thyristors to simultaneously reduce voltage across all three phases, ensuring balanced starting.

Thyristor yana da uku terminals: anode, cathode, da gate. Current flow ba zai ƙara har zuwa inda aka ƙara voltage pulse a gate, wanda yake trigger thyristor da kuma ƙara current ta ƙare kan. Amma amount of current or voltage da aka kontrola da thyristor yana daɗi ƙara ta hanyar adjusting the firing angle of the gate signal—wannan mechanism yana ƙara inrush current da aka bayar da motoci a lokacin fadada.

A lokacin fadada motoci, firing angle yana ƙara ta hanyar bayar da low voltage, wanda yake ƙara ta hanyar as motoci yake ƙara. Idan voltage yake ƙara line voltage, motoci yake ƙara daɗin da aka rara. Bypass contactor typically employed to supply line voltage directly during normal operation.

A lokacin kafin mutumta cikin motoci, process yana ƙara ta hanyar ƙara voltage ta ƙare gradually before cutting off the input supply. Saboda soft starter yana ƙara supply voltage only during startup and shutdown, it cannot adjust motor speed during normal operation, limiting its use to constant-speed applications.

Abubuwan da suka fiye da soft starters su ne:

• No Harmonic Generation: Eliminates the need for additional harmonic filters.

• Compact Design: Smaller footprint than VFDs due to fewer components, reducing overall cost.

VFD (Variable Frequency Drive)

A variable frequency drive (VFD) shine semiconductor-based motor starter wanda yake taimakawa da fadada da kafin mutumta cikin motoci, kuma yana ƙara full-speed control during operation. Unlike soft starters, VFDs regulate both supply voltage and frequency. Since the speed of an induction motor is directly tied to supply frequency, VFDs are ideal for applications requiring dynamic speed adjustment.

VFD consists of three core circuits: a rectifier, a DC filter, and an inverter. The process begins with the rectifier converting AC line voltage to DC, which is then smoothed by the DC filter. The inverter circuit subsequently transforms the steady DC voltage back into AC, with its logic control system enabling precise adjustment of both the output voltage and frequency. This allows the motor speed to ramp smoothly from 0 RPM to its rated speed—and even beyond by increasing the frequency—providing comprehensive control over the motor’s torque-speed characteristics.

By varying the supply frequency, a VFD enables dynamic speed adjustment during operation, making it ideal for applications requiring real-time speed modulation. Examples include fans that adjust speed based on temperature and water pumps that respond to incoming water pressure. Since motor torque is directly proportional to both supply current and voltage, the VFD’s ability to regulate both parameters allows for fine-grained torque control.

In contrast to traditional starters like DOL (direct-on-line) and soft starters—which can only run the motor at full speed or stop it—VFDs optimize power consumption by allowing the motor to operate at programmed speeds. However, this versatility comes with trade-offs: VFDs generate line harmonics, necessitating additional filters, and their complex circuitry (comprising rectifiers, filters, and inverters) results in a larger form factor and higher cost—typically three times that of a soft starter.