VFD for 3-phase induction motor

[NEERAJ GUPTA]

i need to design the VFD for given 3 phase AC induction motor . i m considering below given reference design: 

https://www.st.com/en/evaluation-tools/steval-ihm023v3.html

Kindly! suggest me how to implement the changes in hardware & firmware which shall suit the characteristics of this motor.if this reference design is wrong, then which design i should consider.

NOTE: This motor should be able to work under constant & variable load both. Please! guide how to implement functional safety in firmware & hardware to prevent electrical shock, sparking, injury & permanent damage to this motor. Also This design should be able to drive similar motor upto 1 horsepower. 

3 - phase AC induction Motor Specifications:

• Brand: Siemens

• Type: 3 Phase Induction Motor (EFF2)

• Model Number: 1LA0 073-4YA8

• Standard Compliance: IEC 60034-1, IS: 325, IS: 12615

• Efficiency: 66.0%

• IP Rating: IP55 (dust protected, water jet resistant)

• Duty Type: S1 (Continuous duty)

• Insulation Class: F

• Frame Size: 71

• Weight: 9.0 kg

• Motor No.: SDF/8887 2075604

• Ambient Temperature Rating: 50°C

• Power Supply Frequency: 50 Hz ±5%

• Rated Voltage: 415 V (Y configuration) ±10%

• Power Output: 0.37 kW

• Current: 1.05 A

• Speed: 1380 RPM

• Power Factor: 0.74

• Country of Manufacture: Made in India

• Series: CHAMPION

[GMA]

Hello @NEERAJ GUPTA,

Use the Software example available here.

Refer to STM32 MC SDK AC Induction Motor wiki page.

[NEERAJ GUPTA]

Dear GMA,

                Thanks for your reply. This can be acceptable for firmware part. But what about the hardware design.
If i m correct, then the following changes need to be incorporated given below:

DC Bus Capacitors

• Original Part: Electrolytic capacitors rated 450V (e.g., C15, C16, C17).

• Issue: After rectifying 415V AC → peak voltage ≈ 415V × √2 ≈ 586V, which exceeds 450V rating.

 Required Upgrade: Use 600V or 630V rated capacitors, or film capacitors designed for 600V DC.

Bridge Rectifier (D1 – KBU6K)

• Original Part: 600V bridge rectifier.

• Issue: Same as above — rectified voltage exceeds 600V.
  Required Upgrade: Use KBU8K or GBU8K, rated 800V/8A minimum.

IPM Module – STGIPN3H60DF

• Specs: 600V, 3A IGBT IPM.

• Issue: Max voltage 600V – borderline safe; no headroom. Your motor draws ~1.05A, which is OK current-wise.

  Required Upgrade:

  • i want safe design margins, should upgrade to STGIPN6K60 (600V, 6A).

  • Or better: use STGIPN10K60 (600V, 10A) if available.

  • If 600V is risky, will go with higher voltage-rated discrete IGBT/MOSFETs and custom driver.

Voltage Divider Resistors (VBUS Sensing)

• Original: R49, R50, R51 used to scale DC bus to ADC voltage.

• Issue: Must be recalculated to handle ~580V DC input and not exceed 3.3V ADC input.
  Preventive Action: Recalculate divider ratio and use resistors rated for high voltage (≥250V each, series chain preferred).

Shunt Resistors (Current Sensing)

• Original: Low-ohmic resistors (e.g., R44, R47), likely sized for ~2–3 A motors.

• Our Motor: 1.05 A → May not need change.

        Check:

• Power rating (I²R losses) should handle full current.

• If seeing signal saturation or poor resolution, then adjust.

  
  Heatsink for IPM

  • IPM likely to heat under 1.05 A continuous load

Action: Use metal heatsink or add fan cooling if motor runs at full load.

Bootstrap Capacitors (C23–C25)

• Original: 100nF/630V film caps.

• Your Motor’s VBUS: ~580V

Keep as-is if 630V rating is confirmed on those caps.

Protection Components (Zener, TVS)

• TVS/Zeners across DC bus or gate drive protection should have:

  • >600V standoff voltage

  • Review D4, D10, D22, etc.
    

    Upgrade to:

    • 600–650V TVS (e.g., P6KE600CA)

    • Ensure proper clamping margin
      
      

      Fuse (F1)

      • Original: 6.25A fuse

      • Your Load: 1.05 A continuous
        Use slow-blow fuse, rated ~2A or 3A @ 600VAC, unless inrush is high.
        
        

EMI/Filter Components

• L1, C1, C13, C18, etc. Optional but recommended to upgrade for 415V AC line filtering using proper X2/Y2 caps and CM choke rated for 600VAC.

This is my rough idea regarding the changes required in the electronic components. I have some inputs but i cannot certify if these combinations will work efficiently without any overheating motor due to over-voltage or over-current & how to connect this motor in correct fashion to prevent the electrical hazard like sparking. 
Please! revert me with your suggestions.   

[novaksta]

Dear Mr. GUPTA,

unfortunately previously mentioned board STEVAL-IHM023V3 is NRND and is not available. The software example may be actually found in X-CUBE-MCSDK v6.3.2 (please use this version), unfortunately for this unavailable board. 

I have previously ported this example to more recent board STEVAL-IPM15B (porting to other SLLIMM based STEVAL-IPM boards should be simple), available at github (VF_OL, FOC).

For the hardware design, this is rather question for different support team than mine, nevertheless STEVAL-IPM15B may be considered as hardware reference design for motor control solutions (as approach using SLLIMM inverter).

Best regards,

Stanislav

[NEERAJ GUPTA]

Dear Novaksta, 

Thanks for your suggestions. Here given below changes required to done for compatibility & functional safety of AC induction motor:

Required Changes / Considerations:

1. DC Bus Input Design Needs External Stage
- Add a 3-phase diode bridge rectifier and bulk capacitor bank (e.g., 400–800 µF @ 600 V) before the IPM board

2. DC Bus Capacitor Rating May Be Insufficient
- Use external high-voltage electrolytic capacitors or film capacitors (≥ 600 V rating, total ~100–200 µF minimum)

3. Protection Circuit Missing for Mains Connection
- Add: Input fuse, MOVs, NTC thermistor, EMI filter

4. Control Interface Isolation
- Add digital isolators (e.g., Si8621 or HCPL-series) between microcontroller and IPM board for PWM and EM_STOP signals

5. Cooling Arrangement
- Monitor NTC output. Optionally add fan control or overtemperature shutdown logic.

Again this is my rough idea regarding the changes required in the electronic components. I have some inputs but i cannot certify if these combinations will work efficiently without any overheating motor due to over-voltage or over-current & how to connect this motor in correct fashion to prevent the electrical hazard like sparking.
Please! revert me with your suggestions.

[novaksta]

Dear Mr. GUPTA,

thank you for the update.

Firstly as I have mentioned power design is not directly my expertise (I am microcontroller supporter). If I understood correctly the latest comment is related to the IPM15B board (at least for initial try may be useful, nevertheless for the motor you got the board is probably too powerful (board 1.5KW, whereas motor is 0.37 kW as you are mentioning)), am I right? In such case there are my comments to your points.

1. IPM15B needs for its operation C1 bulk capacitor (not fitted when delivered, however 400–800 µF @ 450 V, the board is up to 400VDC (400V should be enough for motor operation)), as you are considering diode bridge rectifier yes when source is AC. Nevertheless if you have possibility to have 400 VDC power supply for testing I would recommend that. There is also needed heat sinks for the board (not included with the board).

2. Board up to 400VDC and this should be enough for motor operation, I suggest.

3. Fuse is reasonable idea (to be safe not sorry), other protections it depends -- (NTC thermistor it depends where it will be sensing the temperature)

4. Isolation, may be used (in many applications necessary, it depends on final schematic whether), however it would depend where form the mcu will be powered.

5.It depend on the motor, howe fast and how often and about the load (how warm it will get) -- I suggest, firstly the motor should be somehow turning.

With regards,

Stanislav NOVAK
ST mcu support

[NEERAJ GUPTA]

Dear  novaksta ,

Thanks for your reply. i have spent large portion of my career to resolve the compatibility between embedded hardware & firmware. Therefore, your answer found to be almost aligned with my thinking process. i sincerely think that i need to consider consult the end user about finalizing the motor specifications. Reason is ,i think VFD design would become much simpler if end user chooses with dual voltage compatibility (230V delta / 415V star) before design work can be started & this can be accepted as solution.  

With regards,

NEERAJ GUPTA