If

1
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where ?2 ltlt ?1 ? cycloconvertor
If
Input voltage (50 Hz)
Load voltage (10 Hz)
Load current (10 Hz)
B1
B2
Input current distorted (has also sub-harmonics)
2
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Voltage Source Inverter
Current Source Inverter
Inductive load
Capacitive (voltage Source) dc-link
Inductive (Current Source) dc-link
Capacitive load
Voltage Source Converter (rectifierinverter)
Cdc
Vdcunipolar
Current Source Converter (rectifierinverter)
Ldc
Idcunipolar
3
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Ldc/2
3-ph Voltage Supply
3-ph R-L Load
Cdc
3-ph Diode Rectifier
Ldc/2
3-ph PWM Voltage Source Inverter
L-C smoothingbased on energy storage components

• Small dc-link voltage ripple still present (no
  filter is perfect!!)
• The 6 V ripple compared to 550 V mean value
  (1) causes no visible impact on output voltage
  current waveform
• What would be the effect of reducing the filter
  size (cost)?

4
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Reduced dc-link capacitor size ??Vdc 70 V
70 V
No dc-link capacitor ??Vdc 80 V
80 V
No dc-link capacitor ? still able to operate !!
5
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H-bridge output voltage Vdc(2dutycycle - 1)
VdcVout linear dependency Vdc ripple ? Vout
distortion
compensation Vdc ripple ? no visible distortion
in output waveforms
120?
Input currenttypical diode rectifier with
Idconst (current source rectifier)
6
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Bidirectional switches on input side give the
possibility to commutate the dc-link current to
the input line of choice increase conduction
angle from 120 to 180 degrees and shape the
average input current?sinus
It is possible to combine the functionality of
rectifier stage switches and inverter stage
switches
MATRIX CONVERTER
Virtual Single Stage AC/AC converter with no
dc-link storage, sine wave input current sine
wave output voltage capability
Problems many semiconductor devices, Vout 86
Vin, sensitive to input voltage disturbances
7
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8
http//hermes.eee.nott.ac.uk/teaching/h5cpe2/
Load current sign controlled commutation

• Better measure currents than voltages
• Suitable for 3/1 phase modular approach
• Inductive currents give a more stable sign
  signal
• Failure in detecting the correct sign causes
  dead-time commutation (Li2 small if offset)

9
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