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A single-phase AC induction motor is a brushless motor designed with a single stator coil. ST offers state-of-art, rugged devices such as TRIACs, thyristors and AC switches, allowing motor speeds to be regulated in various ways, depending on the cost and performance requirements of the final application.

  • Bi-directional drives

    When a motor with a permanent phase-shift capacitor is used, the direction of rotation can be reversed by means of two AC switches connecting the phase-shift capacitor in series with either of the two stator windings.

  • Phase-controlled drives

    ST offers a silent and cost-effective variable speed drive with an innovative topology to control motor speed. A simple phase-control switch is used to vary speed by changing the motor torque.

    • Working principles

      A single-phase motor with a coil winding is the simplest type of AC motor but needs a starting mechanism. This leads to the three main types of single-phase induction motor: shaded-pole, split-phased, and capacitor motors.

      Starting the motor can be achieved by designing the stator with two windings, a main and auxiliary coil. Connecting a capacitor in series with the auxiliary winding means the current flows through both coils are out of phase. It is this phase difference that generates a torque to start the rotation.

      An electrolytic start capacitor is used to achieve the best phase angles between start and main windings and is disconnected from the start circuit when the motor reaches about 75% of full-load speed. It is designed for short-time duty, and using it for longer than necessary can cause problems, so the accurate control is essential.

      Main types

      • Shaded-pole induction motors

        A shaded-pole motor uses a squirrel cage rotor and usually range from 1/20th to 1/6th of a horsepower for small motors. This has additional windings in each corner of the stator, called shade windings. These are not connected but generate a current from the induced field. This inhibits the field, creating a low torque to get the motor moving.

      • Split-phase induction motors

        A split-phase induction motor has two windings, a run winding and a secondary start winding, and usually operate up to 1/3 horsepower to drive blades on a ceiling fan, washing machines tubs, blower motors for oil furnaces, and small pumps.

        The higher power start winding gets the motor moving up to 75 to 80% of its speed, and then a centrifugal switch is used to switch over to the less powerful run coil to save energy.

      Considerations

      single phase motor for industrial pumps

      Single-phase AC motors are extremely common in all walks of life. The vast majority of motors powered by the household or light industrial mains supply are single phase.

      One of the keys is to size the motor correctly for the application. If the motor doesn’t generate enough torque for the design it will always be running at maximum, putting more strain on the components and generating too much heat. Similarly, if the motor is too big it will not operate efficiently and will waste energy.

      However, single-phase power sources can be used to generate a three-phase variable frequency supply to drive a 3-phase induction motor.

      A single-phase induction motor drive can also see torque ripple, which is a regular change in the output torque, and the difference between the maximum and minimum figure is often expressed as a percentage to highlight the controllability of the motor.

      Fault detection in single-phase induction motors usually requires sensors as there is not sufficient information to implement more complex sensorless algorithms.

Block diagram

Part Number
Description
STEVAL-IHM029V2 Universal motor control evaluation board based on the STM8S103F2 MCU and T1235T Triac Quick view

Key Features

  • Input voltage range: 90-265 VAC, 50/60 Hz
  • 12 VDC / 5 VDC auxiliary power supply based on the VIPer16L in buck converter topology
  • Total power consumption below 300 mW in standby mode
  • Maximum output power: 1500 W
  • 20-pin, 8-bit STM8S103F2 MCU as main controller
  • Employs zero-voltage switching (ZVS) to synchronize MCU events with the voltage mains
  • Motor driven by T1235T Triac in phase-angle control
  • 5 power levels and standby mode selectable by potentiometer
  • 5 LEDs to display the power level of the board
  • “RUN” LED to indicate the board is functioning
  • Standard in-circuit programming connector
  • IEC 61000-4-4 pre-compliance test passed (burst up to 8 kV)
  • IEC 61000-4-5 pre-compliance test passed (surge up to 2 kV)
  • RoHS compliant

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FEATURED RESOURCES

Schematics BOM Gerber
STEVAL-IHM041V1 Universal motor driver with speed control based on the STM8 and Triac (US version) Quick view

Key Features

  • Input voltage 120 V/60 Hz
  • Motor current: 7 A RMS
  • Phase control for universal motor drive
  • Open loop or closed loop speed regulation
  • Voltage and current sensing, for sensorless operation (optional)
  • Debug outputs
  • AC tach, Hall sensor or opto-sensor for speed feedback
  • RoHS compliant

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FEATURED RESOURCES

Schematics BOM Gerber
STEVAL-IHT001V2 Cold thermostat kit based on AC switches and the STM8S Quick view

Key Features

  • Low-cost solution for spark-free thermostats:
    • No need for a sealed version
    • Low-cost STM8S microcontroller for thermostat control
    • Low-cost capacitive power supply
  • High efficiency:
    • Refrigerator consumption reduction by adjusting and reducing the hysteresis threshold of the temperature
    • Improved efficiency by turning on the defrost resistor only when it's useful and not at each OFF cycle of the compressor (as done in some mechanical thermostats)
  • High system immunity:
    • Overvoltage protected ACS switches: ACST610-8FP for compressor control, ACS110-7SN for defrost resistor and ACS102-6TA for light bulb and fan
    • Class A criteria for IEC 61000-4-4 up to above 3 kV levels
  • Flexibility:
    • Development: program setting with PC interface to change firmware variables
    • Industrialization: end-of-production MCU programming thanks to FLASH, for soft upgrade and efficient MCU stock management
  • RoHS compliant

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FEATURED RESOURCES

Schematics BOM Gerber
STEVAL-GLA001V1 Triac and AC switch insulated control evaluation board Quick view

Key Features

  • Insulated control of three different AC switches used to drive AC loads up to 1 kW (230 Vrms) for residential appliances
  • Interface with STM32 Nucleo-64 development board
  • Three control modes available thanks to STM32 Nucleo-64 firmware (continuous or pulse gate current, timer option and phase control)
  • Easy to configure through user-friendly interface
  • Compatible with any external microcontroller
  • Input voltage range: 90 VAC to 265 VAC 50 / 60 Hz
  • Operating temperature: 0 °C to 60 °C
  • 5 V and 3.3 V insulated power supply
  • Low standby power losses (< 300 mW)
  • Criteria A @ 2 kV IEC 61000-4-4
  • Criteria B @ 4 kV IEC 61000-4-4
  • RoHS compliant

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IMAGE

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FEATURED RESOURCES

Schematics BOM Gerber
Part Number
STEVAL-IHM029V2

Universal motor control evaluation board based on the STM8S103F2 MCU and T1235T Triac

Key Features

  • Input voltage range: 90-265 VAC, 50/60 Hz
  • 12 VDC / 5 VDC auxiliary power supply based on the VIPer16L in buck converter topology
  • Total power consumption below 300 mW in standby mode
  • Maximum output power: 1500 W
  • 20-pin, 8-bit STM8S103F2 MCU as main controller
  • Employs zero-voltage switching (ZVS) to synchronize MCU events with the voltage mains
  • Motor driven by T1235T Triac in phase-angle control
  • 5 power levels and standby mode selectable by potentiometer
  • 5 LEDs to display the power level of the board
  • “RUN” LED to indicate the board is functioning
  • Standard in-circuit programming connector
  • IEC 61000-4-4 pre-compliance test passed (burst up to 8 kV)
  • IEC 61000-4-5 pre-compliance test passed (surge up to 2 kV)
  • RoHS compliant

Show More

IMAGE

Image
Image

FEATURED RESOURCES

Schematics BOM Gerber
STEVAL-IHM041V1

Universal motor driver with speed control based on the STM8 and Triac (US version)

Key Features

  • Input voltage 120 V/60 Hz
  • Motor current: 7 A RMS
  • Phase control for universal motor drive
  • Open loop or closed loop speed regulation
  • Voltage and current sensing, for sensorless operation (optional)
  • Debug outputs
  • AC tach, Hall sensor or opto-sensor for speed feedback
  • RoHS compliant

Show More

IMAGE

Image
Image

FEATURED RESOURCES

Schematics BOM Gerber
STEVAL-IHT001V2

Cold thermostat kit based on AC switches and the STM8S

Key Features

  • Low-cost solution for spark-free thermostats:
    • No need for a sealed version
    • Low-cost STM8S microcontroller for thermostat control
    • Low-cost capacitive power supply
  • High efficiency:
    • Refrigerator consumption reduction by adjusting and reducing the hysteresis threshold of the temperature
    • Improved efficiency by turning on the defrost resistor only when it's useful and not at each OFF cycle of the compressor (as done in some mechanical thermostats)
  • High system immunity:
    • Overvoltage protected ACS switches: ACST610-8FP for compressor control, ACS110-7SN for defrost resistor and ACS102-6TA for light bulb and fan
    • Class A criteria for IEC 61000-4-4 up to above 3 kV levels
  • Flexibility:
    • Development: program setting with PC interface to change firmware variables
    • Industrialization: end-of-production MCU programming thanks to FLASH, for soft upgrade and efficient MCU stock management
  • RoHS compliant

Show More

IMAGE

Image
Image

FEATURED RESOURCES

Schematics BOM Gerber
STEVAL-GLA001V1

Triac and AC switch insulated control evaluation board

Key Features

  • Insulated control of three different AC switches used to drive AC loads up to 1 kW (230 Vrms) for residential appliances
  • Interface with STM32 Nucleo-64 development board
  • Three control modes available thanks to STM32 Nucleo-64 firmware (continuous or pulse gate current, timer option and phase control)
  • Easy to configure through user-friendly interface
  • Compatible with any external microcontroller
  • Input voltage range: 90 VAC to 265 VAC 50 / 60 Hz
  • Operating temperature: 0 °C to 60 °C
  • 5 V and 3.3 V insulated power supply
  • Low standby power losses (< 300 mW)
  • Criteria A @ 2 kV IEC 61000-4-4
  • Criteria B @ 4 kV IEC 61000-4-4
  • RoHS compliant

Show More

IMAGE

Image
Image

FEATURED RESOURCES

Schematics BOM Gerber
00 Files selected for download

Technical Documentation

    • Description Version Size Action
      AN4607
      Basics on the thyristor (SCR) structure and its application
      2.0
      317.41 KB
      PDF
      AN4363
      How to select the Triac, ACS, or ACST that fits your application
      2.1
      361.44 KB
      PDF
      AN3168
      Non-insulated SCR / Triac control circuits
      1.2
      315.8 KB
      PDF
      AN303
      Thyristors and TRIACs: latching current
      3.4
      164.96 KB
      PDF
      AN4607

      Basics on the thyristor (SCR) structure and its application

      AN4363

      How to select the Triac, ACS, or ACST that fits your application

      AN3168

      Non-insulated SCR / Triac control circuits

      AN303

      Thyristors and TRIACs: latching current

Publications and Collaterals

    • Description Version Size Action
      T-series Triacs: immunity and commutation driven for AC appliances 3.0
      676.39 KB
      PDF

      T-series Triacs: immunity and commutation driven for AC appliances

    • Description Version Size Action
      Thyristors, Triacs, AC switches and A.S.D™ selection guide 2.0
      1.51 MB
      PDF

      Thyristors, Triacs, AC switches and A.S.D™ selection guide

Microcontrollers & Microprocessors

Part number Description
STM8S105S4 Mainstream Access line 8-bit MCU with 16 Kbytes Flash, 16 MHz CPU, integrated EEPROM
Part number
Mainstream Access line 8-bit MCU with 16 Kbytes Flash, 16 MHz CPU, integrated EEPROM

Thyristors (SCR) and AC Switches

Part number Description
ACST1035-8FP Overvoltage protected 10 A 800 V AC switch
ACST1235-8FP Overvoltage protected AC switch
ACST1635-8FP Overvoltage protected AC switch
T1235H 12 A - 600 V - 150 °C H-series Triacs
T1635H 16 A - 600 V - 150 °C H-series Triacs
T3035H 30 A - 600 V - 150 °C H-series Triacs
T835H 8 A - 600 V - 150°C H-series Triacs
Part number
Overvoltage protected 10 A 800 V AC switch
Overvoltage protected AC switch
Overvoltage protected AC switch
12 A - 600 V - 150 °C H-series Triacs
16 A - 600 V - 150 °C H-series Triacs
30 A - 600 V - 150 °C H-series Triacs
8 A - 600 V - 150°C H-series Triacs