Mechatronics

1. MOD 5 INVERTERS
Dr.Sudha.L.K.
Asst.Prof.
EIE, BIT

2. INVERTERS
 Inverters are static power converters that produce an AC output
waveform from a DC power supply.
 adjustable AC speed drives
 Uninterruptible Power Supplies (UPS),
 shunt active power filter, etc.
 For sinusoidal AC outputs, the magnitude, frequency, and phase
should be controllable.
 If a DC input is a voltage source, then the inverter is called a Voltage
Source Inverter (VSI).
 Similarly in case of a Current Source Inverter (CSI), the input to the
circuit is a current source.
 The VSI circuit has a capability of controlling AC output voltage,
whereas the CSI directly controls AC output current.
 Sketch of output voltage waveforms by an ideal VSI, should be
independent of load connected at the output.

3. Types of Inverters
VSI-Voltage Source Inverter
CSI-Current Source Inverter
Single phase inverter (VSI)
Three phase Inverter (VSI)
They are divided into two categories.
1. Half bridge Single Phase Voltage Source Inverter
2. Full bridge Single Phase Voltage Source Inverter

5. HALF BRIDGE VOLTAGE SOURCE INVERTER
This type of inverter is the basic building block of a half
bridge inverter. It contains two switches and each of its
capacitors has a voltage output equal to Vdc/2. In
addition, the switches complement each other, that is,
if one is switched ON the other one goes OFF.
Fig:1

7. Fig: 2 Waveforms of a half bridge rectifier

9. FULL BRIDGE INVERTER
 This inverter circuit converts DC to AC. It achieves
this by closing and opening the switches in the
right sequence. It has four different operating
states which are based on which switches are
closed.

10. Three Phase Inverter
• A three-phase inverter converts a DC input into a three-phase AC output. Its three
arms are normally delayed by an angle of 120° so as to generate a three-phase AC
supply. The inverter switches each has a ratio of 50% and switching occurs after every
T/6 of the time T 60°angleinterval60°angleinterval. The switches S1 and S4, the
switches S2 and S5 and switches S3 and S6 complement each other.
• The figure below shows a circuit for a three phase inverter. It is nothing but three single
phase inverters put across the same DC source. The pole voltages in a three phase
inverter are equal to the pole voltages in single phase

13.  The current source inverter converts the input direct current into an alternating
current. In current source inverter, the input current remains constant but this input
current is adjustable. The current source inverter is also called current fed inverter.
The output voltage of the inverter is independent of the load. The magnitude and
nature of the load current depends on the nature of load impedance.
Current Source Inverter