Field weakening Control for Induction motors.pptx

Contains field weaking control in Induction motor

1. 22EERM0 ELECTRIC VEHICLES VECTOR CONTROL OF INDUCTION MOTOR BY, KANISHKA M 22E 038

2. INTRODUCTION Vector control/ Independent/ Decoupled method of induction motors is a significant advancement in motor control technology, allowing for independent control of torque and flux , which enables induction motors to perform similarly to DC motors. Vector control or FOC, enhances induction motor performance by separately controlling torque and flux. Additionally, vector control utilizes Clarke and Park transformations to achieve DC motor-like precision in speed and torque control. This method enhances the dynamic response of the motor, achieving better control over speed, torque, and position. Overall, vector-controlled induction motors are robust, reliable, and maintenance-free alternatives to DC drives. Applications: EVs, Robotics, Industrial drives

3. PRINCIPLE OF VECTOR CONTROL Vector control of induction motors works by decoupling the motor’s magnetic flux and torque, allowing each to be controlled independently. The principle is based on the creation of a rotating reference frame aligned with the rotor flux. Thus, motor control is transformed into a linear problem corresponding to a separately excited DC motor. By controlling both the magnitude and phase of each phase current and voltage , which helps overcome the limitations of traditional control methods. Two types: Direct and Indirect FOC

4. INDIRECT FOC

5. COMPONENTS OF VECTOR CONTROLLED IM Induction Motor: The primary component that converts electrical energy into mechanical energy. Current Controller: controls current and gives desired voltage to IM Shaft Encoder: An essential component used to measure the rotor’s position and speed. Power Inverter: This component converts DC power into AC power for the motor. 2/3 Phase transformation: converts ids, iqs to 3-ph reference currents

6. METHODOLGY Rotor speed feedback: Rotor speed measured by shaft encoder. To calculate slip speed and electrical angle. Calculate rotor flux angle: From Rotor speed, slip speed, Rotor parameters(R, L). Crucial for Rotating reference frame. Transform Currents: Clarke Transformation: 3-ph currents stator to 2 axis ( α-β ) stationary frame. 𝑖𝛼 =𝑖𝑎 𝑖𝛽 =1/sqrt(3)(𝑖𝑏−𝑖𝑐) Park Transformation: Rotates α-β frame into d-q frame aligned with rotor flux Control d-q currents: Using PI controllers D axis- rotor flux current Q axis- Torque control current

7. Inverse transformations: Inverse park– d-q to α-β Space vector modulation: α-β to 3-ph PWM signals. Inverter drives the motor from the PWM signals generated. The motor produces desired torque and speed. ADVANTAGES Stable and reliable Easy to implement Ideal for high performance applications.

8. DIRECT FOC

9. METHODOLOGY Measure the motor quantities (phase voltages and currents) Transform them to the 2-phase system (α,β) using a Clarke transformation Calculate the rotor flux space vector magnitude and position angle Transform stator currents to the d-q coordinate system using a Park transformation The stator current torque and flux producing components are separately controlled The output stator voltage space vector is calculated using the decoupling block The stator voltage space vector is transformed by an inverse Park transformation back from the d-q coordinate system to the 2-phase system fixed with the stator Using the space vector modulation, the output 3-phase voltage is generated

10. ADVANTAGES: No sensor required More accurate Faster dynamic response Needs flux observer to it makes the operation complex. Flux estimated from stator signals.

11. REFERENCES https://www.electricity-magnetism.org/vector-controlled-induction-motor/ Vector-Controlled Induction Motor https://www.eeeguide.com/vector-control-of-induction-motor/ Vector Control of Induction Motor https://www.brainkart.com/article/Vector-Control-of-AC-Induction-Machines_12662/ Vector Control of AC Induction Machines