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3相感应电机(ACIM)

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三相感应电机是无刷电机。定子为铜绕组,转子是典型的铝质松鼠笼结构。典型的驱动器配置是一个三相桥(3个半桥),调制之后提供三路正弦波电压给定子。因为通常用于大功率应用,驱动部分可以由功率MOSFET或带有高压栅极驱动电路的IGBT组成,或者由集成了三个半桥和相关栅极驱动级的功率模块组成。磁场定向控制或标量(伏特/赫兹)控制算法是在控制逆变器的微控制器中实现的。 Read more

Our products and solutions

We offer the entire range of power semiconductors and ICs including discrete IGBTs and power MOSFETs as well as power modules and intelligent power modules (IPM), high-voltage gate drivers and powerful STM32 microcontrollers needed to implement high-efficiency variable-frequency drive (VFD) motor control. 

To help reduce and simplify the design cycle, we offer a complete ecosystem of hardware, evaluation boards and reference designs, as well as firmware and software libraries.

 

Working principles of a 3-phase induction motor

In a 3-phase AC induction motor, there are three stator windings, each usually in two halves, with the rotor winding short-circuited by end rings. As the current passes through the coils on opposite sides of the stator, a two-pole electromagnet is established, creating a two-pole motor. Applying a phase to each of the electromagnets in turn creates the rotating magnetic field that is strong enough to start moving the rotor. 

More winding can create more poles in the motor, with more complex control required but more accuracy in positioning the rotor. A four-pole motor is regarded as optimum for the torque and responsiveness needed to for the motor drives of electric cars, for example. But higher pole counts are only possible with more sophisticated control schemes. 

The typical drive has three half-bridges, each delivering a sine-wave voltage to the stator. This uses power MOSFETs or IGBTs with high-voltage gate drivers, or power modules that combine the three half-bridges and related gate drives. These can use scalar algorithms that vary the voltage to determine the frequency of the phases, or volts/hertz. More sophisticated algorithms such as vector control or Field-Oriented Control(FOC) are used to control the frequency of multiple phases in high-end motors are now increasingly popular across the range of three-phase induction motors. 

Polyphase motors generally cover three-phase motors using multiple poles.

Self-starting and soft-start controllers

A soft-start controller is used in three-phase AC induction motors to reduce the load on the self-starting motor and the current surge of the motor during start-up. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power cables and electrical distribution network, extending the lifespan of the system. 

Induction motors can have inrush currents seven to ten times that of the operational current. Starting torques can be 3 times higher to overcome the starting conditions, causing mechanical stress on the components in the motor. So electronic soft starters use a control system to reduce the torque by temporarily reducing the voltage or current input until the induction motor reaches its synchronous speed. 

A digital soft-starter controller continuously monitors the voltage during start-up, adjusting to the load of the motor to provide a smooth acceleration and the speed control. This is often done with connected silicon-controlled rectifiers (thyristors) controlling each phase separately to give the optimum control.

Direct torque control

The torque generated in the rotor of a 3-phase induction motor is proportional to the flux generated by each stator pole, the rotor current and the power factor of the rotor. Direct torque control (DTC) is a technique used in variable frequency drives. It comes from estimating the magnetic flux from the voltage and current of the motor. This is compared to a reference value to control the torque. 

This allows the flux and the torque to be changed quickly by changing the references, making the motor more efficient and reducing power losses as only the exact current is used. This also avoids the rotor overshooting, allowing more accurate control over the motor.

Fault diagnosis

Three-phase induction motors are a key part of almost every industrial process. So there are many methods for fault detection and diagnosis to make sure that the motors keep the production lines running

However, despite the high level of reliability of these motors, most of the methods require a good deal of expertise to apply successfully, looking at the voltage, current, vibration or the thermal profile. Simpler approaches are needed so that any line operators can make reliable decisions. And motor makers want to reduce the number of sensors in the motor as they can fail and cause reliability problems. 

Rotor faults may occur during production as small faults, or may result from production faults or mechanical, environmental, electromagnetic or thermal pressure on the rotor when the motor runs. Even if these faults are small at first, the faults grow over time, and a broken or cracked rotor can cause neighboring components to fail from increased currents and thermal activity. 

Machine learning is increasingly being used to monitor the performance of motors, comparing the patterns of different types of data used in the control systems to predict any potential failure.

Working principles of a 3-phase induction motor

In a 3-phase AC induction motor, there are three stator windings, each usually in two halves, with the rotor winding short-circuited by end rings. As the current passes through the coils on opposite sides of the stator, a two-pole electromagnet is established, creating a two-pole motor. Applying a phase to each of the electromagnets in turn creates the rotating magnetic field that is strong enough to start moving the rotor. 

More winding can create more poles in the motor, with more complex control required but more accuracy in positioning the rotor. A four-pole motor is regarded as optimum for the torque and responsiveness needed to for the motor drives of electric cars, for example. But higher pole counts are only possible with more sophisticated control schemes. 

The typical drive has three half-bridges, each delivering a sine-wave voltage to the stator. This uses invalid link: /en/motor-drivers/gate-drivers.html#productspower MOSFETs or IGBTs with high-voltage gate drivers, or invalid link: /en/power-modules/stpower-sllimm-intelligent-modules.html#productspower modules that combine the three half-bridges and related gate drives. These can use scalar algorithms that vary the voltage to determine the frequency of the phases, or volts/hertz. More sophisticated algorithms such as vector control or invalid link: /en/applications/industrial-motor-control/3-phase-field-oriented-control-foc.htmlField-Oriented Control(FOC) are used to control the frequency of multiple phases in high-end motors are now increasingly popular across the range of three-phase induction motors. 

Polyphase motors generally cover three-phase motors using multiple poles.

Picture Solution
100W High Voltage Motor Control Solution for 3-phase Inverters
SL-MCIMC00302V1
批量生产
100W High Voltage Motor Control Solution for 3-phase Inverters
SL-MCIMC00302V1
批量生产

All tools & software

    • 产品型号
      状态
      描述
      类型
      供应商

      STSW-POWERSTUDIO

      批量生产

      功率器件的ST PowerStudio动态电热模拟软件

      评估工具软件 ST
      STSW-POWERSTUDIO

      描述:

      功率器件的ST PowerStudio动态电热模拟软件
    • 产品型号
      状态
      描述
      类型
      供应商

      STSW-STM8020

      批量生产

      STM8S和STM8A BLDC和ACIM电机控制固件库V1.0(UM0708)

      STM8微控制器软件 ST
      STSW-STM8020

      描述:

      STM8S和STM8A BLDC和ACIM电机控制固件库V1.0(UM0708)