Microcontroller homework for week 10 1. PID control scheme: Equation describing the PID control: Differences between ,,bang-bang" control and proportional control: Proportional 0%...100% As error decreases, output decreases, e.g. reduces overshoot ,,Bang-bang" 0% or 100% Only 2 states (that's why also called On/off control). It has feedback. Similar to PWM ouput signal. Integral and Derivative terms in the PID equation: These are time-based terms: theintegral is an integral over some time period, and the derivative is the derivative between two time periods. Derivative to measure how fast the error is changing; rate of change in error gives indication
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Bang-Bang control is similar to the PWM input signal Proportional control: Bang-Bang control and Proportional control So that: ON-Off Control: When error = 0, turn OFF, when error ≠ 0, turn ON (Gain not changed). Proportional Control: Output = G x e. If e great -> G great, e small -> G small (Gain changes upon the value of error, so better). Functions of Integral and Derivative terms in the PID equation: (page 113-114) D for derivative, reduce overshoot and ocillation, error is rising fast, D great, error rising slow, D small, error not changed, D=0. Still offset error. I for integral, eliminate the offset error. Offset error great -> I great, offset error small -> I small, offset erro = 0, I = 0. Question 2 (30 marks) A PID controller is implemented using the below equation: 1 t de(t )
· The rigidity of the high-efficient electrical drives is high · The standard supply grid has the oscillation period of 20 ms · Select the components that belong to the servo drive position sensor · The multi-quadrant operation is typical for car · If the required speed would rise, the mechanical time constant do not change · At the very low speed the torque is less than rated · In the case of low quick action the overtorque is 0 · The overshot of the stable system no overshoot · The usual time response processes are step · In the accurate drives, the accuracy range is small · Select the motors with the slip rings wound-rotor synchronous · Select the natural reference frames L1, L2, L3 · Select the stationary reference frames , · If the stator field frequency is 100, what will be the synchronous frequency of the 2- pole motor? 100 · Select the correct frequency equilibrium 1 = 2 + 12 12 = 1 - 2
7. Which time constant is usually the longest and which one is the shortest ? thermal, mechanical, or electromagnetic? 8. Does the mechanical time constant depend on the steady-state torque? 9. How does the drive speed action depend on the time constants? 10. Does the drive overspeed affects the drive accuracy? 11. How does the drive overcurrent affects the drive speed action? 12. How does the drive overtorque affects the drive speed action? 13. How does the overshoot of the stable system change in the course of the process? 14. What are the oscillation period and the frequency of the standard supply grid? 15. What are the important features of the steady-state mode? 16. What variables the mechanical characteristics describe? 17. What variables the electromechanical characteristics describe? 18. How does the drive effectiveness depend on the overload capacity? 19. How does the drive accuracy depend on the speed range? 20
speed The speed range of the high - efficient electrical drives is high. In the generator mode, the motor brakes. The counter-torque of the hoist is active/reactive/inductive (pakuks active) The friction torque is passive/reactive/inductive (pakuks reactive) In the case of high quick action tauT is short ja taue is short In the case of low quick action the overtorque is 0. The overshot of the stable system - no overshoot. The usual time response processes are step (äkki peaks miskit veel olema?) In the accurate drives, the accuracy range is small. How does the drive accuracy depend on the speed range? the speed rigidity? the overload capacity? The higher, the better. Why is the torque restricted at the very low speed? In the range of the low speeds due to the cooling deterioration, the load derating is recommended up to 15...30 %.
This pulse reduces the potential across the membrane for a brief instant. If the pulse is weak, nothing further will happen; there is no impulse. If the strength of the pulse is slowly increased, the resting potential drops still more, but there's no impulse. This continues until the pulse is strong enough to decrease the potential to a critical point, the threshold. Now a new phenomena occurs. The potential suddenly collapses; in fact, it overshoot the zero mark and for a brief moment the axon interior becomes positive relative to the outside. This brief flare lasts about 1 millisecond and quickly subsides. The potential then returns to the resting state. This entire sequence of electrical evets is called the action potential. The all-or-none law: One point must be stressed. Size of the reaction is unaffected by the intensity of the stimulus, once the stimulus is a t threshold level or above. Increasing the
3 is similar to that for a real system that I worked on once. The heater control circuit could put significant energy into the heater, much more than was needed to heat the object in question. The object being heated had fairly low mass, almost as low as the heater itself, so it heated quickly. In fact, the object being heated changed temperature faster than the thermistor responded to temperature changes. In the actual system, when the heater was turned on, it would overshoot the desired setpoint in just a few seconds, then stay off for 10 or 20 seconds while the temperature came back down. After that, the oscillation around the set- point was fairly large. I picked a particularly bad example to illustrate these concepts. On-off control is not necessarily a bad means of controlling something, if it is matched to the requirements. On-off control works best in a situation where: • The object being controlled does not respond quickly to changes in the
dramatically.Only the resistance of the external circuit limits the maximum value of current. 8)For power diodes, switching process is the most common operation mode. A power diode requires a finite time interval to switch over from the off-state to the on-state or vice versa. Switching properties are analyzed at a given rate of current change. The most essential data of power switching are the forward voltage overshoot(UF(max)) when a diode turns on and the reverse current peak value(IR(max)) when a diode turns off. If Ploss=0, the efficiency is approx. Equial to 25% 50% 75% 100% What are the sources of current? carriers electrons neutrons protons Ticket No 2 Varactor Zener diode Bi-directional diode Schottky LED Photodiode Optocoupler(LED and photo)
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