3-level PWM vs 2-level PWM - Revision history

Tero K: /* Effects */

2015-04-15T22:13:43Z

‎Effects

Tero K at 11:55, 13 March 2015

2015-03-13T11:55:33Z

Tero K at 11:55, 13 March 2015

2015-03-13T11:55:19Z

Tero K: /* Simulated waveforms */

2014-07-08T23:10:59Z

‎Simulated waveforms

Tero K: /* Simulated waveforms */

2014-07-08T23:08:42Z

‎Simulated waveforms

Tero K at 23:05, 8 July 2014

2014-07-08T23:05:56Z

Tero K at 23:01, 8 July 2014

2014-07-08T23:01:55Z

Tero K: Created page with "Typical motor drive based controls motor coil current by outputting PWM signal which is basically high frequency on/off switching of HV DC bus voltage. Switching volta..."

2014-07-08T23:01:06Z

Created page with "Typical motor drive based controls motor coil current by outputting PWM signal which is basically high frequency on/off switching of HV DC bus voltage. Switching volta..."

New page

Typical motor drive based controls motor coil current by outputting [[PWM]] signal which is basically high frequency on/off switching of [[HV DC bus]] voltage. Switching voltage on and off yields low heat dissipation from drive compared to linear amplifier designs. Typical PWM based drive typically operates around 90% power conversion efficiency while linear amplifiers rarely operate above 50% efficiency.
==PWM switching schemes==
[[File:Drive 3ph motor.png|thumb|Current drive principle of PWM based motor drive|400px]]
In motor control, two most common switching schemes are conventional 2-level a.k.a. antiphase PWM and more modern 3-level PWM.
;2 level PWM
:The outputs of antiphase or 2-level PWM are inversions of each other. The effective output voltage is the average of voltage differential over inductive load such as motor coil. Coil is driven either full positive or full negative voltage of [[HV DC bus]]. Full positive voltage induces maximum current change in positive direction and vice versa. Switching between positive and negative output yields sawtooth like current ripple over coil.
;3 level PWM
:The output of 3-level PWM are in-phase with each other which yields three distinct voltage levels of voltage differential over the load. The third voltage level is ''zero voltage'' which features lower current rate of change in the coil yielding lower total current ripple.
==2-level PWM simulation waveforms==
[[File:Pwm2level m.PNG]]
==3-level PWM simulation waveforms==
[[File:Pwm3level m.PNG]]
[[Category:Glossary]]
[[Category:Technology]]

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 ==Effects==
 While 3 level PWM may require more sophisticated control circuity, it gives benefits of notably reduced ripple current which has benefits such as reduced motor heat dissipation and longer motor bearing life. Current ripple directly relates wearing bearings due to eddy currents in metallic materials.
 [[Category:Glossary]]
 [[Category:Technology]]
 [[Category:Argon features]]
 [[Category:IONI features]]

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 [[Category:Technology]]
 [[Category:Argon features]]
-[[Category:Ioni features]]
+[[Category:IONI features]]

@@ Line 21: / Line 21: @@
 [[Category:Technology]]
 [[Category:Argon features]]
-[[Category:Ion features]]
+[[Category:Ioni features]]

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 :The output of 3-level PWM are in-phase with each other which yields three distinct voltage levels of voltage differential over the load. The third voltage level is ''zero voltage'' which features lower current rate of change in the coil yielding lower total current ripple.
 ==Simulated waveforms==
-These simulations display a case where one coil is being driven with 2 and 3 level PWMs. All simulation parameters are kept same, only difference is the switching scheme.
+These simulations display a case where one coil is being driven with 2 and 3 level PWMs. Coil is being driven with PWM outputs where duty cycles are modulated sinusoidally to create sinusoidal current. All simulation parameters are kept same, only difference is the switching scheme.
 ===2-level PWM===
 [[File:Pwm2level m.PNG]]

@@ Line 8: / Line 8: @@
 :The output of 3-level PWM are in-phase with each other which yields three distinct voltage levels of voltage differential over the load. The third voltage level is ''zero voltage'' which features lower current rate of change in the coil yielding lower total current ripple.
 ==Simulated waveforms==
 ===2-level PWM===
 [[File:Pwm2level m.PNG]]
 ===3-level PWM===
 [[File:Pwm3level m.PNG]]
 ==Effects==
 While 3 level PWM may require more sophisticated control circuity, it gives benefits of notably reduced ripple current which has benefits such as reduced motor heat dissipation and longer motor bearing life. Current ripple directly relates wearing bearings due to eddy currents in metallic materials.

← Older revision		Revision as of 23:01, 8 July 2014
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	[[Category:Glossary]]		[[Category:Glossary]]
	[[Category:Technology]]		[[Category:Technology]]
		+	[[Category:Argon features]]
		+	[[Category:Ion features]]