IR21771S International Rectifier, IR21771S Datasheet - Page 13

• Manufacturer Part Number: IR21771S
• Description: 600V Phase Current Sensing IC for AC Motor Control in a 16-Lead SOIC package
• Manufacturer: International Rectifier

Specifications of IR21771S

• Family Hvic: General Purpose HVICs
• Channels: 1
• Topology: Current Sense
• Application: General Purpose / Motor Control
• Voffset: 600
• Over Current Protection: Yes
• Package: 16 Lead
• Part Status: Active & Preferred

For this particular PWM scheme another suitable
solution is driving the IR2x771 with a half frequency
SYNC signal (f
In this case the cut frequency of the input filter is
1.6 Input filter gain setting
G0 and G1 pins are used to change the time
constant of the integrators of the high side input
filter.
To avoid internal saturation of the input filter, G0
and G1 must be connected according to SYNC
frequency as shown in Table 1. A too small time
constant may saturate the internal integrator, while
a large time constant may reduce accuracy.
13
SYNC
=f
PWM
/2).
Figure 15: Even harmonic cancellation principle
reduced by half allowing zeroes to be put at f
multiples (i.e. even and odd harmonics cancellation,
no more computational effort needed by the
controller).
G0 and G1 do not affect the overall current sensor
gain.
Third
Third
Third
Third
harmonic
harmonic
harmonic
harmonic
harmonic
harmonic
harmonic
harmonic
SYNC 1
SYNC 1
SYNC 2
SYNC 2
Phase voltage
Phase voltage
Phase current
Phase current
Current Mean
Current Mean
Fundamental
Fundamental
Fundamental
Fundamental
Switching level
Switching level
IR22771S/IR21771S(PbF)
Triangular
Triangular
Error
Error
*
Table 1: G0, G1 gain settings
f
> 16 kHz *
16 / 10 kHz
10 / 6 kHz
< 6 kHz
PWM
40 kHz
instant
instant
instant
instant
Sampling
Sampling
Sampling
Sampling
harmonic only)
Stage 1 input:
Input signal
components
(1
Stage 1
st
output
and 2
nd
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G0
V
V
V
V
B
S
B
S
G1
V
V
V
V
B
B
S
S
PWM