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DC-DC Converter Drives

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Presentation on theme: "DC-DC Converter Drives"— Presentation transcript:

1 DC-DC Converter Drives
Principle of Power Control Principle of Regenerative Brake Control Principle of Rheostatic Brake Control Combined Regenerative and Rheostatic Brake Control Two and Four Quadrant DC – DC Converter Drives ECE 442 Power Electronics

2 Converter-fed DC Drive for a Separately-Excited Motor
ECE 442 Power Electronics

3 Waveform Summary Highly Inductive Load
Ripple-free Armature Current ECE 442 Power Electronics

4 Principle of Power Control
The average armature voltage is The power supplied to the motor is ECE 442 Power Electronics

5 Principle of Power Control (continued)
The average value of the input current is The equivalent input resistance seen by the source is Control Power Flow by adjusting the duty cycle ECE 442 Power Electronics

6 Principle of Power Control (continued)
To find the maximum peak-to-peak ripple current ECE 442 Power Electronics

7 ECE 442 Power Electronics

8 ECE 442 Power Electronics

9 ECE 442 Power Electronics

10 Application of a DC – DC Converter in Regenerative Braking
ECE 442 Power Electronics

11 Waveform Summary Armature Current Continuous and Ripple-Free
ECE 442 Power Electronics

12 Regenerative Braking Begin with the motor turning by kinetic energy of the vehicle Armature current flows as shown Turn the transistor on Armature current rises Turn the transistor off Diode turns on, current flows into the supply ECE 442 Power Electronics

13 Principle of Regenerative Braking
The average voltage across the transistor is The regenerated power can be found from ECE 442 Power Electronics

14 Principle of Regenerative Braking (continued)
The voltage generated by the motor acting as a generator is The equivalent load resistance of the motor acting as a generator is Control Power by changing k ECE 442 Power Electronics

15 Minimum Braking Speed Maximum Braking Speed ECE 442 Power Electronics

16 For this example, the field and armature need to be in series
ECE 442 Power Electronics

17 ECE 442 Power Electronics

18 ECE 442 Power Electronics

19 Rheostatic Brake Control Dynamic Braking
ECE 442 Power Electronics

20 Waveform Summary ECE 442 Power Electronics

21 Principle of Rheostatic Brake Control
The average current in the braking resistor is The average voltage across the braking resistor is ECE 442 Power Electronics

22 Principle of Rheostatic Brake Control (continued)
The equivalent load resistance of the generator The power dissipated in the resistor Rb is ECE 442 Power Electronics

23 ECE 442 Power Electronics

24 ECE 442 Power Electronics

25 ECE 442 Power Electronics

26 Combined Regenerative and Rheostatic Brake Control
ECE 442 Power Electronics

27 Combined Regenerative and Rheostatic Brake Control (continued)
Used when the supply is partly “receptive” Remove regenerative braking if line voltage is too high Turn thyristor TR on Divert current to RB Apply rheostatic braking TR is “self-commutated” ECE 442 Power Electronics

28 Two-Quadrant DC–DC Converter Drive
ECE 442 Power Electronics

29 Quadrant Operation Summary
Regenerative Braking Control Power Control ECE 442 Power Electronics

30 Power Control Q1 and D2 operate Q1 ON, Vs applied to the motor
Q1 turned OFF, D2 “free-wheels” Armature current decays ECE 442 Power Electronics

31 Regenerative Control Q2 and D1 operate
Q2 turned ON, motor acts as a generator, and the armature current rises Q2 turned OFF, motor returns energy to the supply via D1 “free-wheeling” ECE 442 Power Electronics

32 Four Quadrant DC-DC Converter Drive
ECE 442 Power Electronics

33 Quadrant Operation Summary
Forward Regeneration Forward Power Control Reverse Power Control Reverse Regeneration ECE 442 Power Electronics

34 Forward Power Control Q1 and Q2 turned ON
Supply voltage appears across the motor Armature current rises Q1 and Q2 turned OFF Armature current decays via D3 and D4 ECE 442 Power Electronics

35 Forward Regeneration Q1, Q2, and Q3 turned OFF Turn Q4 ON
Armature current rises and flows through Q4, D2 Q4 turned OFF, motor acts as a generator, returns energy back to the supply via D1, D2 ia reverses ECE 442 Power Electronics

36 Reverse Power Control Q3 and Q4 turned ON
Supply voltage appears in the reverse direction across the motor Armature current rises and flows in the reverse direction Q3 and Q4 turned OFF Armature current decays via D1 and D2 ia ECE 442 Power Electronics

37 Reverse Regeneration Q1, Q3, Q4 turned OFF Q2 turned ON
Armature current rises through Q2 and D4 Q2 turned OFF Armature current falls and returns energy via D3 and D4 i a ECE 442 Power Electronics


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