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SPWM Generation
- Thread starter skandesh
- Start date
jbartos
Electrical
- Jan 15, 2000
- 6,440
Suggestion: Visit
etc. for more info
Please, notice that
The frequency modulation ratio mf=fs/f1
where
fs is switching frequency or carrier frequency
f1 is desired fundamental frequency of the inverter voltage output or modulating frequency
etc. for more info
Please, notice that
The frequency modulation ratio mf=fs/f1
where
fs is switching frequency or carrier frequency
f1 is desired fundamental frequency of the inverter voltage output or modulating frequency
Digital servo amplifiers manufacturers claim that "Space-vector modulation delivers higher motor speed and lower motor power dissipation than conventional sine-PWM modulation"
and this is absolutely true.
It is about dynamic range of motor fundamental voltage non-distorted by saturation.
For conventional analog 3-phase sinusoidal PWM suggested by Siemens engineers in 1964 (triangular wave scanning of 3 sinusoidal voltage commands) and 3-phase Y-connected motor maximum non-distorted phase-to-phase (line) voltage is about 15% less than DC bus voltage. This is also the case of 3-phase linear (not PWM) servo amplifier.
There seems to be no physical reason preventing maximum non-distorted fundamental line voltage from reaching DC bus one and this is realized by space-vector modulation.
It is claimed that there is no necessity in digital current loop to gain those 15% of DC bus voltage back and that this could be done by simple analog means that will also work for linear amplifier
and this is absolutely true.
It is about dynamic range of motor fundamental voltage non-distorted by saturation.
For conventional analog 3-phase sinusoidal PWM suggested by Siemens engineers in 1964 (triangular wave scanning of 3 sinusoidal voltage commands) and 3-phase Y-connected motor maximum non-distorted phase-to-phase (line) voltage is about 15% less than DC bus voltage. This is also the case of 3-phase linear (not PWM) servo amplifier.
There seems to be no physical reason preventing maximum non-distorted fundamental line voltage from reaching DC bus one and this is realized by space-vector modulation.
It is claimed that there is no necessity in digital current loop to gain those 15% of DC bus voltage back and that this could be done by simple analog means that will also work for linear amplifier
Another digital servo amplifiers manufacturer about additional 15% of voltage / speed from SPWM :
BTW, it is about pure sinusoidal modulation - for extra speed overmodulation strategy also counts.
BTW, it is about pure sinusoidal modulation - for extra speed overmodulation strategy also counts.
For another useful pointer see Forum discussion at
jbartos
Electrical
- Jan 15, 2000
- 6,440
Suggestion: I recommend grasping the principles of modulation techniques, e.g. visit
etc. for more info
etc. for more info
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