A Teardown of the Yaskawa Sigma-7 Servo Amplifier

This teardown looks at the inner workings of the Yaskawa Sigma-7, anAC servo drive for industrial applications.

The Yaskawa Sigma-7 is part of a line of industrial servo amplifiers. The Sigma-7 servo drive achieves a frequency response of 3.1 kHz assures high speed response and improved settling time.

The Sigma-7 servo drive series has a power rating rangingfrom 3W to 55kW, can be easily paired with Yaskawa machine controller and various types of servo motors to create a motion automation system. The Sigma-7 servo drive come in single-axis and dual-axis variations, can be used to drive rotary servo motors, gear motors, direct drive servo motors and linear servo motors. With advanced set of servo tuning algorithms for vibration suppression, autotuning and tuning-less commissioning without the need for installer intervention, that result in reduced settling times, reliably precise control and faster setup of a new automation system.

The Sigma-7 servo amplifier series is designed for easy integration with various communication portssuch as Mechatrolink III Ethernet (1000Mbps and up to 62 slaves synchronization), EtherCAT, CompactLogix PLC, PLCopen programming standard, Modbus TCP protocol, and RS422.

The Sigma-7 servo drive is used in a wide variety of applications including industrial robots, semiconductor equipment, and various stage of industrial automation.


General Specifications

  • Model and Ratings: SGD7S-2R1F20A, 200W, 2.1A, 240V, 3-phase output
  • Main Supply: Single Phase 100Vac to 120Vac, 50Hz / 60Hz, 5A
  • Control Power Supply: AC Single Phase 100Vac to 120Vac, 50Hz / 60Hz, 0.38A
  • speed frequency response: 500Hz
  • 24-bit encoder input
  • Additional Features: Option for regenerative resistor module, advanced servo tuning algorithms for vibration suppression, auto-tuning and tuning-less commissioning,

External and Enclosure 

  • Dimensions: 18cm x 16cm x 4cm
  • Weight: 1.4kg
  • Operating ambient temperature: -5° to 55°C, 95% relative humidity
  • Degree of Protection: IP20
  • Installation class: A maximum altitude of 1000m (derating for 1000m to 2000m), without corrosive or flammable gases, exposure to water, oil, or chemicals, dust, salt or iron powder.


Controller Board

  • MCU: Yaskawa ASIC
  • Isolation: Toshiba
    • TLP2368 (2pcs) AC input, 5Mbps high-speed photocoupler.
    • TLP290 (4 pcs) AC input, photo-transistor.
    • TLP291 (2 pcs) DC input, photo-transistor.

Inverter Board

  • AC input line to DC rectifier circuit:

– Shindengen MG020200 with integrated diode rectifiers for AC input line / DC converter and braking IGBT and diode

– AC input line voltage detector with isolation: Toshiba TLP785 (2 pcs) DC input, Viso 5000Vrms,phototx

– Panasonic ZNR E11271 transient / surge absorbers

– Mersen AC400V/DC260V, 20A fuse

  • Relay for inrush current limiter:

– Omron G6C-2114P SPST-NO 10A

– Inrush Resistor: Tamura F5K 5.1ΩJ, 145°Cand 5K 5.1ΩJ cement resistor

  • Flyback converterswitched mode power supply (SMPS):

– Texas Instrument UCC28610flyback controller IC, 12-65W

– T4057DTflyback transformer

– Shindengen G10SC6M schottky barrier diode 60V, 10A

– Isolation: Toshiba TLP785 (2 pcs) DC input, Viso 5000Vrms, phototx

  • Bulk DC Capacitor: Rubycon (2pcs) 200V/1300µF electrolytic capacitor
  • Braking Gate Driver: Broadcom ACPL-P314 0.6A, IGBT gate drive photocoupler
  • Inverter circuit:

– Bus voltage sensing with isolation: Broadcom ACPL-C797, 200mV input, 10MHz clock, optically isolated, delta-sigma modulator

– Mitsubishi PSS10S51F6 intelligent power module 3-phase DC/AC inverter, 600V/10A

-Gate drive with isolation: Broadcom ACPL-P480 (6 pcs)photocoupler

– Phototransistor with isolation for IPM temperature sensing: Toshiba TLP785 DC input, Viso 5000Vrms, phototx

– Output phase current sensing: Broadcom ACPL-796J 200mV input, external clock up to 20MHz, optically isolated, delta-sigma modulator

– 30mΩ shunt resistor (2 pcs)


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