1. Controlled-Rectifier Fed Drive
Armature Field

2. Chopper-Fed Drive
Armature Field
ECE 442 Power Electronics

3. Equivalent Circuit of a Separately-Excited DC Motor
ECE 442 Power Electronics

4. ECE 442 Power Electronics

5. ECE 442 Power Electronics

6. Solve for the motor speed
ECE 442 Power Electronics

7. Control of the motor speed
Control armature voltage, Va
Voltage control
Control the field current, If
Current control
Control the armature current, Ia
ECE 442 Power Electronics

8. Magnetization Characteristic
ECE 442 Power Electronics

9. Characteristics of Separately-Excited Motors
Use armature voltage control
Use field-current control
Rated speed
ECE 442 Power Electronics

10. Equivalent circuit of a DC Series Motor
ECE 442 Power Electronics

11. ECE 442 Power Electronics

12. Controlling the Motor Speed
Control the armature voltage, Va
Control the armature current, Ia
ECE 442 Power Electronics

13. Characteristics of DC Series motors
ECE 442 Power Electronics

14. Operating Modes
In variable-speed applications, a dc motor may be operating in one or more of the following “Modes”
Motoring
Regenerative braking
Dynamic braking
Plugging
ECE 442 Power Electronics

15. Motoring Mode “Back emf”, Eg is < supply voltage Va
Both Ia and If are positive
Developed torque meets load demand
ECE 442 Power Electronics

16. Regenerative Braking Mode
Motor acts as a Generator
Eg becomes > supply Voltage Va
Ia becomes negative
Kinetic energy of the motor is returned to the supply
ECE 442 Power Electronics

17. Dynamic Braking Replace the supply voltage with a resistor
Power dissipated in the resistor rather than given back to the source
ECE 442 Power Electronics

18. Plugging Reverse the armature terminals while running
Va and Eg act in the same direction
Ia is reversed, producing “braking” torque
ECE 442 Power Electronics

19. Four-Quadrant Operation
ECE 442 Power Electronics

20. Single-Phase DC Drive
Change Va by changing firing angle  Inductor Lm is a “smoothing” Inductor to prevent discontinuous current
ECE 442 Power Electronics

21. Armature Reversal
ECE 442 Power Electronics

22. Field Reversal
ECE 442 Power Electronics

23. Single-Phase Half-Wave Converter Drive
ECE 442 Power Electronics

24. Quadrant of Operation
ECE 442 Power Electronics

25. Waveform Summary
ECE 442 Power Electronics

26. Single-Phase Semiconverter Drives
ECE 442 Power Electronics

27. Quadrant(s) of Operation
Semiconverter – one quadrant converter
One polarity of output voltage and current
ECE 442 Power Electronics

28. Waveform Summary
ECE 442 Power Electronics

29. Single-Phase Full-Converter Drives
ECE 442 Power Electronics

30. Quadrant(s) of Operation
Full converter – two quadrant converter
Output voltage polarity can be positive or negative
Output current has one polarity
ECE 442 Power Electronics

31. Waveform Summary
ECE 442 Power Electronics

32. Single-Phase Dual-Converter Drives
Dual converter can operate in all four quadrants
Output voltage and current can be positive or negative
ECE 442 Power Electronics