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Author Topic: Question on 90V DC motors  (Read 742 times)

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Offline XaviPachecoTopic starter

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Question on 90V DC motors
« on: July 21, 2018, 05:11:03 pm »
Back then, 90V dc motors were controlled by SCRs. Nowadays, some of them are PWM-controlled. Basically my question is:
120VAC rectified and filtered are about 170VDC. For a 90VDC motor, this is too much. The idea on this is controlling the duty cycle under 50%?
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Offline james_s

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Re: Question on 90V DC motors
« Reply #1 on: July 21, 2018, 05:14:10 pm »
Aren't they typically powered by half wave rectified AC using a single diode? I remember seeing that arrangement in electric weed trimmers.
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Offline XaviPachecoTopic starter

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Re: Question on 90V DC motors
« Reply #2 on: July 21, 2018, 05:28:19 pm »
In treadmills, they're powered by full wave rectifiers,  and the output is filtered with a bulk capacitor. 
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Offline Seekonk

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Re: Question on 90V DC motors
« Reply #3 on: July 21, 2018, 06:51:32 pm »
Just because it is full wave doesn't require using the full waveform.  120 partial pulses gives better control than just 60.
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