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Project 2

KK B Sen3 Oct 2023

Project 2

RMXprt Modelling brushless DC Motor

 

Design Procedure in Ansys RMxprt:

 

Step-1: Import the BLDC motor in RMxprt (as given in the Article)

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Step-2: Explore the RMxprt model and give the machine parameters as:

 

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Step-10: Add a solution setup as,

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result

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RMXprt Modelling of 3-Ph Induction Motor

 

 

Motor rating: 1.1 kW Frequency: 50 Hz

Operating voltage: 380V (L-L rms) Nos of poles = 4

Efficiency and Power factor both considered as = 0.8

 

Design Procedure in Ansys RMxprt:

 

Step-1: Import the 3-phase induction motor in RMxprt (as given in the Article)

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Step-2: Explore the RMxprt model and give the machine parameters as:

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Step-3: Double click on the Stator and set:

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Step-4: Double click on Stator slot and set,

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Step-4: Double click on Stator winding and set,

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Step-5: Now, at this moment you should run a theoretical verification as you have all the data available with you.

You can check and determine the following:

<!-- [if !supportLists]-->a.      <!--[endif]-->Number of slots per phase

<!-- [if !supportLists]-->b.     <!--[endif]-->Coil Pitch

<!-- [if !supportLists]-->c.      <!--[endif]-->Pole Pitch

<!-- [if !supportLists]-->d.     <!--[endif]-->Coil Span

<!-- [if !supportLists]-->e.      <!--[endif]-->Angle between consecutive slots

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Displacement in slots between start of Phase A and start of Phase B You should be able to arrive at this diagram (as given by Ansys)

 

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Step-6: Double click on Rotor and set,


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Step-7: Double click on Rotor slot and set,

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Step-8: Double click on Rotor winding and set,

Step-9: Keep the shaft non-magnetic as,

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Step-10: Add a solution setup as,

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Step-11: Set the Setup parameters as,

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Step-12: Do the Validation check,

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Step-13: Right click on the setup and Analyze,

Step-14: Right click on setup and check the Design sheet,

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Step-15: Result Analysis

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From the above analysis in Ansys software, plot the following:

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<!-- [if !supportLists]-->b.     <!--[endif]-->Power factor vs Output power

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<!-- [if !supportLists]-->c.      <!--[endif]-->Torque vs slip

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Find the values of:

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<!-- [if !supportLists]-->b.     <!--[endif]-->Breakdown current per phase


Show the calculations asked in Step-5 and write the answers of:

•         Number of slots per phase

•         Coil Pitch

•         Pole Pitch

•         Coil Span

•         Angle between consecutive slots

•         Displacement in slots between start of Phase A and start of Phase B

 

  1. Number of Slots per Phase (Ns):

Ns = Ss / 3

Here, we divide by 3 because in a three-phase system, each phase is distributed across one-third of the total slots.

  1. Coil Pitch (Yc):

Coil pitch is the distance between the beginnings of two consecutive coils in the same phase. It's usually given as an angle (measured in electrical degrees) and can be calculated as:

Yc = 360° / Ns

  1. Pole Pitch (Yp):

Pole pitch is the distance between the centers of two poles. It can be calculated as:

Yp = 360° / P

  1. Coil Span (Ycs):

Coil span is the angular displacement between the beginnings of two consecutive coils in different phases. It's half of the pole pitch. So,

Ycs = Yp / 2

  1. Angle between Consecutive Slots (Yslot):

This is the angle between the centers of two consecutive slots on the stator. It can be calculated as:

Yslot = 360° / Ss

  1. Displacement in Slots between Start of Phase A and Start of Phase B (ΔSAB):

To find the displacement between the start of Phase A and Phase B, you need to calculate the difference in the slot numbers between the two phases. This depends on the specific motor winding configuration and can vary. If you have the winding diagram or information on how the coils are distributed, you can determine this displacement.


 

Designing the Motors in ANSYS RMxprt:

  1. Motor Specifications:
    • Determine the power rating for both motors.
    • Decide on the stator and rotor material (e.g., iron, copper, etc.) for both motors.
    • Specify other design data such as voltage, current, frequency, and efficiency.
  2. Create New Projects:
    • Open ANSYS RMxprt and create separate projects for the BLDC motor and the induction motor.
  3. Design BLDC Motor:
    • Select the appropriate design type for a BLDC motor.
    • Input the motor specifications, material properties, and operating conditions.
    • Design the stator and rotor, considering factors like the number of poles, winding configuration, air gap, etc.
  4. Design Induction Motor:
    • Select the appropriate design type for an induction motor.
    • Input the motor specifications, material properties, and operating conditions.
    • Design the stator and rotor, considering factors like the number of poles, winding configuration, rotor type, etc.
  5. Simulate the Motors:
    • Run simulations for both motors to obtain performance data such as torque-speed curves, efficiency, and power factor.

Comparing the Results:

  1. Analyze Performance:
    • Compare the obtained results for both motors, including torque-speed curves, efficiency, power factor, and any other relevant parameters.
  2. Prepare a Detailed Report:
    • Create a report that includes the design parameters, materials, simulation results, and a comparison between the BLDC and induction motors.
    • Discuss the advantages and disadvantages of each motor type based on the simulation data.

Speed-Torque Characteristics:

BLDC Motor: BLDC motors typically exhibit linear speed-torque characteristics with precise control over speed and torque. The torque is relatively constant across a wide speed range.

Induction Motor: 3-phase induction motors have a characteristic torque-speed curve with a peak torque at a specific speed. Below this speed, torque decreases, and above it, torque decreases as well.

 

Efficiency:

BLDC Motor: BLDC motors tend to have higher efficiency, especially at partial loads and low speeds, due to precise control over the motor's operation.

Induction Motor: Induction motors have good efficiency, but their efficiency may vary depending on the operating point and load.

Starting Behavior:

BLDC Motor: BLDC motors can start smoothly and operate at very low speeds efficiently. They are well-suited for applications requiring a wide range of speeds.

Induction Motor: Induction motors may require external devices like VFDs for smooth starting and control at low speeds.

Control Precision:

BLDC Motor: BLDC motors offer precise speed and torque control, making them suitable for applications where accuracy is critical.

Induction Motor: Control of induction motors may not be as precise, especially without feedback devices.

Transient Response:

BLDC Motor: BLDC motors have faster transient response due to their low rotor inertia, making them suitable for dynamic applications.

Induction Motor: Induction motors may have a slightly slower transient response due to the higher rotor inertia.

Harmonics and Noise:

BLDC Motor: BLDC motors may produce less harmonic distortion and noise in their operation due to the controlled switching of phases.

Induction Motor: Induction motors may produce more harmonics and noise, especially at low speeds and high loads.

Starting Torque:

BLDC Motor: BLDC motors can provide significant starting torque even at low speeds.

Induction Motor: Induction motors may have limited starting torque at low speeds.

Rotor Slip:

BLDC Motor: BLDC motors do not have rotor slip, as they operate synchronously with the rotating field.

Induction Motor: 3-phase induction motors operate with rotor slip, which affects their speed and torque characteristics.

Steady-State Operation:

BLDC Motor: BLDC motors maintain constant speed under stable conditions, with minimal variation.

Induction Motor: Induction motors may exhibit slight speed variations under varying loads due to slip.

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