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ELECTRIC DRIVES CONVERTERS IN ELECTRIC DRIVE SYSTEMS MODULE 2 Dr. Nik Rumzi Nik Idris Dept. of Energy Conversion, UTM 2013.

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Presentation on theme: "ELECTRIC DRIVES CONVERTERS IN ELECTRIC DRIVE SYSTEMS MODULE 2 Dr. Nik Rumzi Nik Idris Dept. of Energy Conversion, UTM 2013."— Presentation transcript:

1 ELECTRIC DRIVES CONVERTERS IN ELECTRIC DRIVE SYSTEMS MODULE 2 Dr. Nik Rumzi Nik Idris Dept. of Energy Conversion, UTM 2013

2 CONVERTERS - Module 2 AC-DC controlled rectifier approximate model SIMULINK examples open-loop closed-loop Switch Mode DC-DC converter 2-Q and 4-Q converters Small signal modeling unipolar bipolar SIMULINK example Current-controlled for SM converters Bridge converter hysteresis fixed frequency 3-phase VSI hysteresis fixed frequency SVM-based

3 Switch mode DC-DC converter Two-quadrant converter T1 conducts  v a = V dc Q1Q2 VaVa IaIa T1 T2 D1 +Va-+Va- D2 iaia + V dc 

4 Switch mode DC-DC converter Two-quadrant converter Q1Q2 VaVa IaIa T1 T2 D1 +Va-+Va- D2 iaia + V dc  D2 conducts  v a = 0 VaVa EbEb T1 conducts  v a = V dc Quadrant 1 The average voltage is made larger than the back emf

5 Switch mode DC-DC converter Two-quadrant converter Q1Q2 VaVa IaIa T1 T2 D1 +Va-+Va- D2 iaia + V dc  D1 conducts  v a = V dc

6 Switch mode DC-DC converter Two-quadrant converter Q1Q2 VaVa IaIa T1 T2 D1 +Va-+Va- D2 iaia + V dc  T2 conducts  v a = 0 VaVa EbEb D1 conducts  v a = V dc Quadrant 2 The average voltage is made smallerr than the back emf, thus forcing the current to flow in the reverse direction

7 vcvc +Va−+Va− v tri V dc q Switching signals obtained by comparing control signal with triangular wave Switch mode DC-DC converter Two-quadrant converter V a (s)v c (s) DC motor We want to establish a relation between v c and V a ? AVERAGE voltage

8 V dc 0 T tri t on 0 1 V c > V tri V c < V tri vcvc Switch mode DC-DC converter Two-quadrant converter

9 -V tri V tri -V tri vcvc d vcvc 0.5 Switch mode DC-DC converter Two-quadrant converter For v c = -V tri  d = 0

10 0.5 V tri vcvc d vcvc -V tri Switch mode DC-DC converter Two-quadrant converter V tri For v c = -V tri  d = 0 For v c = 0  d = 0.5 For v c = V tri  d = 1

11 0.5 vcvc d -V tri Switch mode DC-DC converter Two-quadrant converter V tri vcvc For v c = -V tri  d = 0 For v c = 0  d = 0.5 For v c = V tri  d = 1

12 Thus relation between v c and V a is obtained as: Introducing perturbation in v c and V a and separating DC and AC components: DC: AC: Switch mode DC-DC converter Two-quadrant converter

13 Taking Laplace Transform on the AC, the transfer function is obtained as: v a (s)v c (s) DC motor Switch mode DC-DC converter Two-quadrant converter

14 Switch mode DC-DC converter Four-quadrant converter leg A leg B + V a  Q1 Q4 Q3 Q2 D1 D3 D2 D4 + V dc  v a = V dc when Q1 and Q2 are ON Positive current

15 Switch mode DC-DC converter Four-quadrant converter leg A leg B + V a  Q1 Q4 Q3 Q2 D1 D3 D2 D4 + V dc  v a = -V dc when D3 and D4 are ON v a = V dc when Q1 and Q2 are ON v a = 0 when current freewheels through Q and D Positive current

16 Switch mode DC-DC converter Four-quadrant converter v a = -V dc when D3 and D4 are ON v a = V dc when Q1 and Q2 are ON v a = 0 when current freewheels through Q and D Positive current v a = V dc when D1 and D2 are ON Negative current leg A leg B + V a  Q1 Q4 Q3 Q2 D1 D3 D2 D4 + V dc 

17 Switch mode DC-DC converter Four-quadrant converter v a = -V dc when D3 and D4 are ON v a = V dc when Q1 and Q2 are ON v a = 0 when current freewheels through Q and D Positive current v a = -V dc when Q3 and Q4 are ON v a = V dc when D1 and D2 are ON v a = 0 when current freewheels through Q and D Negative current leg A leg B + V a  Q1 Q4 Q3 Q2 D1 D3 D2 D4 + V dc 

18 Switch mode DC-DC converter Four-quadrant converter Bipolar switching scheme 2v tri vcvc vcvc v tri + V dc − q -V dc q V dc + V AB  v AB V dc -V dc vBvB V dc 0 vAvA 0

19 Switch mode DC-DC converter Four-quadrant converter Bipolar switching scheme v a (s)v c (s) DC motor

20 Switch mode DC-DC converter Four-quadrant converter Unipolar switching scheme + V dc − vcvc v tri qaqa V dc -v c v tri qbqb Leg a Leg b The same average value we’ve seen for bipolar ! V tri vcvc -v c vAvA vBvB v AB

21 Switch mode DC-DC converter Four-quadrant converter Unipolar switching scheme v a (s)v c (s) DC motor

22 Switch mode DC-DC converter SIMULINK EXAMPLES MATLAB v6.5, SIMULINK v5 2-quadrant converter Open-loop control Closed-loop control (current control)

23 Switch mode DC-DC converter SIMULATION EXAMPLES + V dc  IdId vcvc v tri q 2-quadrant converter rl_2q_average.mdl

24 Switch mode DC-DC converter SIMULATION EXAMPLES 2-quadrant converter Average model

25 Switch mode DC-DC converter SIMULATION EXAMPLES 4-quadrant converter + V dc − vcvc v tri qaqa V dc -v c v tri qbqb Leg a Leg b

26 Switch mode DC-DC converter SIMULATION EXAMPLES 4-quadrant converter Average model unipolar_4q_with_id.mdl

27 Switch mode DC-DC converter SIMULATION EXAMPLES Closed-loop current control H-bridge converter PI i ref + +   Small signal model v c (s) V a (s) I a (s) I ref (s)

28 Switch mode DC-DC converter SIMULATION EXAMPLES Closed-loop current control closed_loop_unipolar_4q_with_id.mdl

29 f tri = Hz 4-quadrant Unipolar 3-phase, 50Hz 2-quadrant DC-DC Switch mode Controlled rectifier Switch mode DC-DC converter SIMULATION EXAMPLES Closed-loop current control For both DC-DC and Contr. Rectifier: Current controlled, I ref = 5 A Load: 250m, 20  Disturbance in DC source: ±70V, at 5Hz

30 f tri = Hz 4-quadrant Unipolar 3-phase, 50Hz 2-quadrant DC-DC Switch mode Controlled rectifier Switch mode DC-DC converter SIMULATION EXAMPLES Closed-loop current control For both DC-DC and Contr. Rectifier: Current controlled, I ref = 5 ± 3 A, freq 5Hz Load: 250m, 20 


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