L13 ic based triggering circuit
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The document discusses a UJT-based triggering circuit design problem with specified parameters and tasks including calculating resistor values and checking their limits. It also covers the TCA 785 phase control IC, which controls thyristors, triacs, and transistors, detailing its features and application scope. Lastly, it assigns a homework question regarding driver and isolation circuits for thyristors, specifically focusing on pulse transformers.
L13 ic based triggering circuit
- 1. EE-321 N Lecture-13 IC Based Triggering Circuit
- 2. Design Problem Based on UJT Trigger Circuit 31-Oct-12 EE-321N, Lec-13 2
- 3. A UJT based triggering circuit has the following specifications: h = 0.65, Ip = 0.8 mA, Vp = 20 V, Iv = 4 mA, Vv = 0.7 V, VD = 0.5 V, RBB = 5 kΩ, VGT = 0.4 V, C = 0.05 µF, f = 2 kHz. Determine (a) The values of R1, R2, R (b) Check whether R is within permissible limits (c) Values of RB1 & RB2 (d) Range of oscillator frequency 31-Oct-12 EE-321N, Lec-13 3
- 4. Solution 31-Oct-12 EE-321N, Lec-13 4 1 1 ln 1 1 1 ln 1 T RC f R f C h h p D p BB D BB V V V V V Vh h (a)
- 5. Solution...contd 31-Oct-12 EE-321N, Lec-13 5 4 2 10 BB R Vh 1 GT 1 1 2 BB BB V R V R R R R
- 6. Solution...contd (b) (c) 31-Oct-12 EE-321N, Lec-13 6 min max BB pBB v v p R R R V VV V R I I 1 1 2 1 B B BB B BB B R R R R R R h
- 7. Solution...contd 31-Oct-12 EE-321N, Lec-13 7 min min max max max min 1 ln 1 1 ln 1 T R C f T R C f h h (d)
- 8. Siemens Phase Control IC TCA 785 • This phase control IC is intended to control thyristors, triacs, and transistors. The trigger pulses can be shifted within a phase angle between 0° and 180°. • Typical applications include converter circuits, AC controllers and three-phase current controllers. 31-Oct-12 EE-321N, Lec-13 8
- 9. Contd... Main Features: • Reliable recognition of zero passage • Large application scope • May be used as zero point switch • Three-phase operation possible (3 ICs) • Output current 250 mA • Large ramp current range • Wide temperature range 31-Oct-12 EE-321N, Lec-13 9
- 10. 31-Oct-12 EE-321N, Lec-13 10 Pin Diagram
- 11. TCA 785 Based Trigger Circuit for SCR & TRIAC 31-Oct-12 EE-321N, Lec-13 11
- 12. 31-Oct-12 12
- 13. Working • DC power synchronized with AC mains is supplied to the IC • Ramp signal is generated internally in the IC and compared with a control signal • Trigger pulse is obtained when both the signals are equal • Pin 15 provides pulses in the +ve half cycle whereas pin 14 provides pulses in –ve half cycle (for TRIAC) 31-Oct-12 EE-321N, Lec-13 13
- 14. 31-Oct-12 EE-321N, Lec-13 14
- 15. Further Resources 1. Moreno et. al., “The Design of a Digital IC for Thyristor Triggering”, Proceedings of Tenth International Conference on VLSI Design, 1997. 2. Siemens TCA 785 datasheet (Available online) 31-Oct-12 EE-321N, Lec-13 15
- 16. Home Assignment Q3. Define Driver & Isolation circuits. Discuss driver & isolation circuits for thyristors. Emphasize on the use of pulse transformers in such circuits. Due Date 10. 11. 12, Saturday Assignments will be submitted in the class at the beginning of the lecture 31-Oct-12 16EE-321N, Lec-12