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rhia
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I am getting confused between duty cycle and frequency of a pwm.
Isn't duty cycle related to frequency?
Can someone explain?
Thanks & regards
Isn't duty cycle related to frequency?
Can someone explain?
Thanks & regards
faust9 said:Duty cycle has very lttle to do with frequency. Here, do this: On a piece of graph paper draw a square wave 6 blocks high and 8 blocks wide for a complete cycle. Split the cycle so the 'on part covers the first four blocks and the off cycle covers the last four blocks of the cycle. The 8 block total width is the frequency, and the duty cycle is 50% (the on off periods are equal).
Now directly below you first graph draw another 8 block cycle but this time draw it so the 'on' time only covers two blocks and the off time covers the remaining 6 blocks. See, the frequency did not change but the duty cycle did. The new duty cycle is 25%.
Can you give real world examples where cycle is not symmetric?Frequency is the a measure of (actually, 1 over the measure of) the time required for a signal to complete 1 full cycle. The cycle does not have to be symetric though.
The duty cycle is a measure of a signals divergence from symmetry. 50%--signal is symmetric. less than 50% and the on time is less than the off time. Greater than 50% and the on time is greater than the off time. But, as illustrated above the frequency of the signal is unchanged by the duty cycle.
Hope this helped.
Good luck.
rhia said:How can there be frequency in off state? off state = no signal =>no freq.
Can you give real world examples where cycle is not symmetric?
Thanks a lot for helping.
Rhia
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rhia said:How can there be frequency in off state? off state = no signal =>no freq.
Can you give real world examples where cycle is not symmetric?
Thanks a lot for helping.
Rhia
The "off" state certainly can be a negative voltage. There's no a priori restriction on what "off" means.cyeokpeng said:The OFF state doesn't mean the -ve state though. It may mean 0 volts or it may mean other voltages, depending on how you define it.
This is nonsense. This is like saying "the usual voltage on wires is 5V." Pulse-width-modulation has nothing to do with actual voltages; it's simply a means of encoding information by changing back and forth between two states, regardless of what voltages (or currents, or whatever) actually define those states.Usually, the OFF state for PWM signal is close to 0V, and the ON state is voltage HIGH.
susi2603 said:I have a doubt and maybe someone in here can help me. I'm controling an electric motor and the PWM signal that I used at first had a frecuency of 50Hz but I'm not going to be able to generate that same signal, so I'm going to generate a PWM signal with 100 Hz. So my question is, how those that affect the information I alredy had about the duty cicle and the angle of the motor.
Duty cycle in PWM (Pulse Width Modulation) is the ratio of the ON time to the total time of a signal. It is expressed as a percentage and determines the amount of power delivered to a load.
Frequency in PWM refers to the number of times the signal switches between ON and OFF per second. The duty cycle and frequency are inversely related - a higher frequency results in a shorter ON time and a lower duty cycle, while a lower frequency results in a longer ON time and a higher duty cycle.
Duty cycle can be calculated by dividing the ON time by the total time of the signal and multiplying by 100 to get a percentage. Frequency can be calculated by taking the inverse of the period, which is the total time of the signal.
PWM is commonly used in electronics to control the amount of power delivered to a load. It allows for precise and efficient control of the average power by varying the duty cycle and frequency of the signal.
Yes, there are limitations to duty cycle and frequency in PWM. Duty cycle is typically limited to a range of 0-100%, while frequency is limited by the capabilities of the hardware and the desired application. It is important to choose appropriate values for duty cycle and frequency to avoid damaging the load or the circuit.