In power electronics, pulse width modulation is a proven effective technique that is used to control semiconductor devices. Pulse width modulation or PWM is a commonly used control technique that generates analog signals from digital devices such as microcontrollers. The signal thus produced will have a train of pulses, and these pulses will be in the form of square waves. Thus, at any given time, the wave will either be high or low. Let us learn more about pulse width modulation in this article.
What is Pulse Width Modulation?
Pulse width modulation reduces the average power delivered by an electrical signal by converting the signal into discrete parts. In the PWM technique, the signal’s energy is distributed through a series of pulses rather than a continuously varying (analogue) signal.
How is a Pulse Width Modulation Signal generated?
A pulse width modulating signal is generated using a comparator. The modulating signal forms one part of the input to the comparator, while the non-sinusoidal wave or sawtooth wave forms the other part of the input. The comparator compares two signals and generates a PWM signal as its output waveform.
If the sawtooth signal is more than the modulating signal, then the output signal is in a “High” state. The value of the magnitude determines the comparator output which defines the width of the pulse generated at the output.
Important Parameters associated with PWM signal
Duty Cycle of PWM
As we know, a PWM signal stays “ON” for a given time and stays “OFF” for a certain time. The percentage of time for which the signal remains “ON” is known as the duty cycle. If the signal is always “ON,” then the signal must have a 100 % duty cycle. The formula to calculate the duty cycle is given as follows:
The average value of the voltage depends on the duty cycle. As a result, the average value can be varied by controlling the width of the “ON” of a pulse.
Frequency of PWM
The frequency of PWM determines how fast a PWM completes a period. The frequency of a pulse is shown in the figure above.
The frequency of PWM can be calculated as follows:
Frequency = 1/Time Period
Time Period = On Time + OFF time
Output Voltage of PWM signal
The output voltage of the PWM signal will be the percentage of the duty cycle. For example, for a 100% duty cycle, if the operating voltage is 5 V then the output voltage will also be 5 V. If the duty cycle is 50%, then the output voltage will be 2.5 V.
Types of Pulse Width Modulation Technique
There are three conventional types of pulse width modulation technique and they are named as follows:
- Trail Edge Modulation – In this technique, the signal’s lead edge is modulated, and the trailing edge is kept fixed.
- Lead Edge Modulation – In this technique, the signal’s lead edge is fixed, and the trailing edge is modulated.
- Pulse Center Two Edge Modulation – In this technique, the pulse centre is fixed and both edges of the pulse are modulated.
Applications of Pulse Width Modulation
Due to the high efficiency, low power loss, and the PWM technique’s ability to precisely control the power, the technique is used in a variety of power applications. Some of the applications of PWM are as follows:
- The pulse width modulation technique is used in telecommunication for encoding purposes.
- The PWM helps in voltage regulation and therefore is used to control the speed of motors.
- The PWM technique controls the fan inside a CPU of the computer, thereby successfully dissipating the heat.
- PWM is used in Audio/Video Amplifiers.
Advantages and Disadvantages of Pulse Width Modulation
First, let us talk about the advantages of the pulse width modulation technique before discussing its disadvantages:
- PWM technique prevents overheating of LED while maintaining its brightness.
- PWM technique is accurate and has a fast response time.
- PWM technique provides a high input power factor.
- PWM technique helps motors generate maximum torque even when they run at lower speeds.
The above were some of the advantages of the Pulse width modulation technique, now let us look at some of the disadvantages:
- As the PWM frequency is high, switching losses are considerably high.
- It induces Radio Frequency Interference (RFI).
Frequently Asked Questions – FAQs
What is Pulse Width Modulation technique?
Pulse width modulation or PWM is a commonly used control technique that generates analog signals from digital devices such as microcontrollers. In PWM technique, the signal’s energy is distributed through a series of pulses rather than a continuously varying (analog) signal.
Why is Pulse Width Modulation used?
Pulse width modulation is an effective method that is used to control the amount of power delivered to a load without dissipating any wasted power.
What is the difference between the duty cycle and the frequency of a PWM signal?
The frequency of a PWM signal describes how often the signal switches between high and low voltages. Frequency is expressed in the unit of Hertz. The duty cycle is the percentage of time the signal stays at a high voltage. It is expressed as the percentage of the period.
What are the different types of Pulse Width Modulation?
The three conventional types of pulse width modulation are:
- Trail Edge Modulation
- Lead Edge Modulation
- Pulse Centre Two Edge Modulation
What are some applications of Pulse Width Modulation?
Owing to its high efficiency, low power loss and the ability of the PWM technique to precisely control the power, the technique is used in a variety of power applications:
- They are used in telecommunication for encoding purposes.
- They are used in Audio/Video amplifiers.
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Katika umeme nguvu, pulse upana modulation ni kuthibitishwa ufanisi mbinu ambayo ni kutumika kudhibiti vifaa semiconductor. PWM (Pulse Width Modulation) ni mbinu ya kawaida ya kudhibiti ambayo inazalisha ishara za analog kutoka kwa vifaa vya dijiti kama vile microcontrollers. Ishara inayotokezwa kwa njia hiyo itakuwa na mfululizo wa msukumo, na msukumo huo utakuwa katika umbo la mawimbi ya mraba. Kwa hiyo, wakati wowote ule, wimbi hilo litakuwa juu au chini. Hebu kujifunza zaidi kuhusu pulse upana modulation katika makala hii. Utaratibu wa Upana wa Puls ni nini? Pulse upana modulation hupunguza wastani nguvu zinazotolewa na ishara ya umeme kwa kubadilisha ishara katika sehemu tofauti. Katika mbinu PWM, nishati ya ishara ni kusambazwa kwa njia ya mfululizo wa pulses badala ya kuendelea kutofautiana (analogue) ishara. Jinsi gani pulse upana modulation ishara ni yanayotokana? Pulse upana modulating ishara ni yanayotokana kwa kutumia comparator. Modulating ishara fomu sehemu moja ya pembejeo kwa comparator, wakati non-sinusoidal wimbi au sawtooth wimbi fomu sehemu nyingine ya pembejeo. Comparator inalinganisha ishara mbili na inazalisha ishara ya PWM kama wimbi lake la pato. Kama sawtooth ishara ni zaidi ya ishara modulating, basi ishara ya pato ni katika <unk>High<unk> hali. Thamani ya ukubwa huamua comparator pato ambayo hufafanua upana wa msukumo yanayotokana katika pato. PWM ishara: PWM ishara ni ishara ya kazi ambayo inahitajika ili kuendesha PWM kwa muda fulani na kisha inahitajika kwa muda fulani. Asilimia ya muda ambayo ishara inabaki <unk>ON<unk> inajulikana kama mzunguko wa kazi. Kama ishara ni daima <unk>ON,<unk> basi ishara lazima kuwa na mzunguko wa kazi ya 100%. formula ya kuhesabu mzunguko wa kazi ni kupewa kama ifuatavyo: Thamani ya wastani wa voltage inategemea mzunguko wa kazi. Matokeo yake, thamani ya wastani inaweza kutofautiana kwa kudhibiti upana wa <unk>ON<unk> ya msukumo. PWM ni kiwango cha kawaida cha PWM, na inategemea jinsi PWM inavyoweza kukamilisha kipindi cha muda. Mzunguko wa msukumo unaonyeshwa katika mchoro wa juu. PWM ni moja ya mifumo ya umeme ya umeme ya umeme, ambayo inahesabiwa kwa kiwango cha voltage ya PWM, ambayo ni asilimia ya mzunguko wa kazi. Kwa mfano, kwa mzunguko wa kazi wa 100% ikiwa voltage ya uendeshaji ni 5V, basi voltage ya pato pia itakuwa 5V. Ikiwa mzunguko wa kazi ni 50%, basi voltage ya pato itakuwa 2.5V. Aina za Mbinu ya Modulation ya Upana wa Pulse Kuna aina tatu za kawaida za mbinu ya modulation ya upana wa pulse na zinaitwa kama ifuatavyo: - Kuongoza Edge Modulation <unk> Katika mbinu hii, ishara ya kuongoza makali ni fasta, na trailing makali ni modulated. - Pulse Center Two Edge Modulation  Katika mbinu hii, kituo cha msukumo ni fasta na kingo zote mbili za msukumo ni modulated. PWM ni mbinu ya nguvu ya umeme ambayo kwa sababu ya ufanisi wake wa juu, hasara ya nguvu ya chini, na uwezo wa PWM kudhibiti nguvu kwa usahihi, mbinu hiyo hutumiwa katika matumizi mbalimbali ya nguvu. Baadhi ya maombi ya PWM ni kama ifuatavyo: - Pulse upana modulation mbinu ni kutumika katika mawasiliano ya simu kwa madhumuni ya encoding. - PWM husaidia katika voltage udhibiti na kwa hiyo ni kutumika kudhibiti kasi ya motors. PWM ni mfumo wa kuendesha kichocheo ndani ya CPU ya kompyuta, na hivyo kuondoa joto. - PWM ni kutumika katika Audio / Video Amplifiers. PWM (Pulse Width Modulation) - PWM ni mbinu ya kuepuka overheating ya LED na kudumisha mwangaza wake. - Mbinu ya PWM ni sahihi na ina wakati wa majibu ya haraka. - PWM mbinu hutoa juu ya pembejeo nguvu sababu. - PWM mbinu husaidia motors kuzalisha torque upeo hata wakati wao kukimbia katika kasi ya chini. PWM ni mbinu ya kuunganisha nguvu za pulse width, na kwa sababu ya hali ya juu ya frequency, hasara ya kuunganisha ni kubwa. - Inachochea Radio Frequency Interference (RFI). Maswali ya mara kwa mara <unk> Maswali ya mara kwa mara Nini ni mbinu ya Modulation Pulse Width? PWM (Pulse Width Modulation) ni mbinu ya kawaida ya kudhibiti ambayo inazalisha ishara za analog kutoka kwa vifaa vya dijiti kama vile microcontrollers. Katika mbinu PWM, nishati ya ishara ni kusambazwa kwa njia ya mfululizo wa pulses badala ya kuendelea kutofautiana (analog) ishara. Kwa nini Pulse Width Modulation hutumiwa? Pulsed upana modulation ni njia ya ufanisi ambayo ni kutumika kudhibiti kiasi cha nguvu zinazotolewa kwa mzigo bila dissipating nguvu yoyote kupoteza. Ni nini tofauti kati ya mzunguko wa kazi na mzunguko wa ishara ya PWM? Mzunguko wa ishara ya PWM inaelezea jinsi mara nyingi ishara hubadilika kati ya voltage ya juu na ya chini. Mzunguko huonyeshwa katika kitengo cha Hertz. mzunguko wa kazi ni asilimia ya muda ishara inabaki katika voltage ya juu. Ni alionyesha kama asilimia ya kipindi. Ni aina gani tofauti za Pulse Width Modulation? Aina tatu za kawaida za pulse upana modulation ni: - Trail Edge Modulation - Lead Edge Modulation - Pulse Center Two Edge Modulation Ni nini baadhi ya maombi ya Pulse Upana Modulation? Kwa sababu ya ufanisi wake wa juu, hasara ya nguvu ya chini na uwezo wa PWM kudhibiti nguvu, mbinu hiyo hutumiwa katika matumizi mbalimbali ya nguvu: - Wao ni kutumika katika Audio / Video amplifiers. Endelea kusikiliza BYJUS na UPATE UPENDO WAKATI ya KUJIFUNZA!