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3-phase Induction Motor (ACIM)

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A 3-phase induction motor uses current delivered in three phases in a sequence into the coils of a stator to create a rotating magnetic field. This induces an electric field in a coil or squirrel cage to drive a rotor. The difference in speed between rotor, the synchronous speed and the rotating magnetic field is called the slip. 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.

All tools & software

    • Part number
      Status
      Description
      Type
      Supplier

      STSW-POWERSTUDIO

      Active

      ST PowerStudio dynamic electrothermal simulation software for power devices

      Evaluation Tool Software ST
      STSW-POWERSTUDIO

      Description:

      ST PowerStudio dynamic electrothermal simulation software for power devices
    • Part number
      Status
      Description
      Type
      Supplier

      STSW-STM8020

      Active

      STM8S and STM8A BLDC and ACIM motor control firmware library V1.0 (UM0708)

      STM8 Embedded Software ST
      STSW-STM8020

      Description:

      STM8S and STM8A BLDC and ACIM motor control firmware library V1.0 (UM0708)

All Hardware Evaluation Tools

    • Part Number
      Description
      Core product
      Tool Type
      Supplier
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      EVAL6393FB

      Active

      Low voltage full bridge reference design board featuring L6393 advanced high-voltage gate driver

      L6393 Brushed Motors -
      EVAL6393FB
      Active

      Low voltage full bridge reference design board featuring L6393 advanced high-voltage gate driver

      EVAL6491HB

      Active

      Demonstration board for L6491 gate driver with smart shut down feature

      L6491 Brushed Motors -
      EVAL6491HB
      Active

      Demonstration board for L6491 gate driver with smart shut down feature

      EVAL6494L

      Active

      Demonstration board for L6494L gate driver

      - Brushed Motors ST
      EVAL6494L
      Active

      Demonstration board for L6494L gate driver

      EVAL6498L

      Active

      Evaluation board for the L6498L gate driver

      - Brushed Motors ST
      EVAL6498L
      Active

      Evaluation board for the L6498L gate driver

      EVALSTDRV600HB8

      Active

      Demonstration board kit for L638xE and L639x high-voltage gate drivers

      L6385E , L6395 Brushed Motors ST
      EVALSTDRV600HB8
      Active

      Demonstration board kit for L638xE and L639x high-voltage gate drivers

      STEVAL-ETH001V1

      Active

      Servo drive solution for multi-axial position control with Ethernet real-time

      STDRIVE101 Communication and Connectivity Solution Eval Boards ST
      STEVAL-ETH001V1
      Active

      Servo drive solution for multi-axial position control with Ethernet real-time

      STEVAL-IHM023V3

      Active

      1 kW 3-phase motor control evaluation board featuring L6390 drivers and STGP10H60DF IGBT

      L6390 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IHM023V3
      Active

      1 kW 3-phase motor control evaluation board featuring L6390 drivers and STGP10H60DF IGBT

      STEVAL-IHM028V2

      NRND

      2 kW 3-phase motor control evaluation board featuring the STGIPS20C60 IGBT intelligent power module

      STGIPS20C60 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IHM028V2
      NRND

      2 kW 3-phase motor control evaluation board featuring the STGIPS20C60 IGBT intelligent power module

      STEVAL-IHM034V2

      NRND

      Dual motor control and PFC demonstration board featuring the STM32F103 and STGIPS20C60

      STGIPS20K60 3-Phase Motors (PMSM, BLDC, ACIM) -
      STEVAL-IHM034V2
      NRND

      Dual motor control and PFC demonstration board featuring the STM32F103 and STGIPS20C60

      STEVAL-IHM039V1

      Active

      Dual motor drive control stage based on the STM32F415ZG microcontroller

      - 3-Phase Motors (PMSM, BLDC, ACIM) -
      STEVAL-IHM039V1
      Active

      Dual motor drive control stage based on the STM32F415ZG microcontroller

      STEVAL-IPM05F

      Active

      500 W motor control power board based on STGIF5CH60TS-L SLLIMM™ 2nd series IPM

      STGIF5CH60TS-L 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IPM05F
      Active

      500 W motor control power board based on STGIF5CH60TS-L SLLIMM™ 2nd series IPM

      STEVAL-IPM07F

      Active

      700 W motor control power board based on STGIF7CH60TS-L SLLIMM™ 2nd series IPM

      STGIF7CH60TS-L 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IPM07F
      Active

      700 W motor control power board based on STGIF7CH60TS-L SLLIMM™ 2nd series IPM

      STEVAL-IPM08B

      Active

      800 W motor control power board based on STGIB8CH60TS-L SLLIMM™ 2nd series IPM

      STGIB8CH60TS-L 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IPM08B
      Active

      800 W motor control power board based on STGIB8CH60TS-L SLLIMM™ 2nd series IPM

      STEVAL-IPM10B

      Active

      1200 W motor control power board based on STGIB10CH60TS-L SLLIMM™ 2nd series IPM

      STGIB10CH60TS-L 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IPM10B
      Active

      1200 W motor control power board based on STGIB10CH60TS-L SLLIMM™ 2nd series IPM

      STEVAL-IPM10F

      Active

      1000 W motor control power board based on STGIF10CH60TS-L SLLIMM™ 2nd series IPM

      STGIF10CH60TS-L 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IPM10F
      Active

      1000 W motor control power board based on STGIF10CH60TS-L SLLIMM™ 2nd series IPM

      STEVAL-IPM15B

      Active

      1500 W motor control power board based on STGIB15CH60TS-L SLLIMM™ 2nd series IPM

      STGIF5CH60TS-L 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IPM15B
      Active

      1500 W motor control power board based on STGIB15CH60TS-L SLLIMM™ 2nd series IPM

      STEVAL-IPMNG8Q

      Active

      600 W motor control power board based on STGIPQ8C60T-HZ SLLIMM™-nano IPM

      STGIPQ8C60T-HZ 3-Phase Motors (PMSM, BLDC, ACIM) ST
      STEVAL-IPMNG8Q
      Active

      600 W motor control power board based on STGIPQ8C60T-HZ SLLIMM™-nano IPM

      STEVAL-ISF003V1

      Active

      Low standby losses power front-end with inrush current-limitation

      TN5050H-12WY PSU and Converter Solution Eval Boards ST
      STEVAL-ISF003V1
      Active

      Low standby losses power front-end with inrush current-limitation

      STEVAL-SCR001V1

      Active

      Inrush current solution with bypass SCR

      TN5015H-6G PSU and Converter Solution Eval Boards -
      STEVAL-SCR001V1
      Active

      Inrush current solution with bypass SCR

      STM32072B-EVAL

      Active

      Evaluation board with STM32F072VB MCU

      STM32F072VB STM32 Eval Boards ST
      STM32072B-EVAL
      Active

      Evaluation board with STM32F072VB MCU

      STM3210E-EVAL

      Active

      Evaluation board with STM32F103Zx MCU

      STM32F103ZE STM32 Eval Boards ST
      STM3210E-EVAL
      Active

      Evaluation board with STM32F103Zx MCU

      STM3220G-EVAL

      Active

      Evaluation board with STM32F207IG MCU

      STM32F207IG STM32 Eval Boards ST
      STM3220G-EVAL
      Active

      Evaluation board with STM32F207IG MCU

      STM32303E-EVAL

      Active

      Evaluation board with STM32F303VE MCU

      STM32F303VE STM32 Eval Boards ST
      STM32303E-EVAL
      Active

      Evaluation board with STM32F303VE MCU

      STM3240G-EVAL

      NRND

      Evaluation board with STM32F407IG MCU

      STM32F407IG STM32 Eval Boards ST
      STM3240G-EVAL
      NRND

      Evaluation board with STM32F407IG MCU

      STM32F769I-EVAL

      Active

      Evaluation board with STM32F769NI MCU

      STM32F769NI STM32 Eval Boards ST
      STM32F769I-EVAL
      Active

      Evaluation board with STM32F769NI MCU

      STM32L476G-EVAL

      Active

      Evaluation board with STM32L476ZG MCU

      STM32L476ZG STM32 Eval Boards ST
      STM32L476G-EVAL
      Active

      Evaluation board with STM32L476ZG MCU

Picture Solution
100W High Voltage Motor Control Solution for 3-phase Inverters
100W High Voltage Motor Control Solution for 3-phase Inverters