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− | [[File:pwm_wiki.png|thumb|PWM signal as | + | [[File:pwm_wiki.png|thumb|PWM signal as reference|400px]] |
− | PWM a.k.a. pulse-width modulation is a voltage waveform usually seen in power electronics such as motor drives and power supplies. It has been also used as [[ | + | PWM a.k.a. pulse-width modulation is a voltage waveform usually seen in power electronics such as motor drives and power supplies. It has been also used as [[Reference signal|referece signal]]. |
The main idea in PWM is to switch voltage either fully ''on'' or ''off'' so rapidly that receiving device "feels" only the average voltage caused by pulsed voltage. | The main idea in PWM is to switch voltage either fully ''on'' or ''off'' so rapidly that receiving device "feels" only the average voltage caused by pulsed voltage. | ||
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* Increased [[Electromagnetic interference|EMI noise]] compared to linear voltage | * Increased [[Electromagnetic interference|EMI noise]] compared to linear voltage | ||
* [[Dead-time distortion]] | * [[Dead-time distortion]] | ||
− | ===As | + | ===As reference signal=== |
− | In some drive models, PWM signal can be used also as [[ | + | In some drive models, PWM signal can be used also as [[reference signal]] to replace analog signal (the +/- 10V control). In this case PWM voltage is typically 3-5V and the duty cycle of signal determines the amplitude. |
− | Compared to analog input in VSD products 0% PWM duty cycle equals -10V, 50% equals 0V and 100% equals +10V. Benefits of using PWM instead of analog | + | Compared to analog input in VSD products 0% PWM duty cycle equals -10V, 50% equals 0V and 100% equals +10V. Benefits of using PWM instead of analog reference: |
* [[Electromagnetic interference|EMI noise]] tolerant | * [[Electromagnetic interference|EMI noise]] tolerant | ||
* Easy to galvanically isolate | * Easy to galvanically isolate | ||
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==Links== | ==Links== | ||
[http://en.wikipedia.org/wiki/Pulse-width_modulation Wikipedia PWM article] | [http://en.wikipedia.org/wiki/Pulse-width_modulation Wikipedia PWM article] | ||
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