Field Oriented Control of Multiple Induction Machines

1
Field Oriented Control of Multiple Induction
Machines

• Brian H. Green
• Power Affiliates Program
• May 12, 2006

2
Field Oriented Control

• Uses dynamic Induction Machine equations
• Controls flux and torque by commanding d and
  q-axis currents

3
Multiple Induction Machines

• Parallel induction machines are used in industry
  with applications such as locomotives
• Single-inverter configurations can be more
  compact and less expensive than standard
  multiple-inverter configurations

4
Mechanical Model
5
Variables to Control

• Control of mechanical power is equivalent to
  control of tractive effort at a given speed
• Control of maximum flux magnitude ensures that no
  machine is excessively magnetized

6
Electrical Model

• Inverter output current is twice the average
  machine current

7
Developing Current Commands

• Express machine quantities in terms of average
  and difference quantities
• Solve for average current values

8
Average Rotor Flux Orientation

• Align d-axis with average rotor flux
• Implies

9
q-axis Current Command

• Solve power output equation for average q-axis
  stator current
• Equation reduces to standard q-axis current
  command when difference terms are zero.

10
d-axis Current Command

• Solve rotor flux magnitude equation for ids (uses
  both rotor dynamic equations)
• Equation reduces to standard d-axis current
  command when difference terms are zero

11
Simulation