UM0324 datasheet(41/105 Pages) STMICROELECTRONICS

41 / 105 page

UM0324

Library functions

41/105

Sector III, VI:

Where T is the PWM period.

Now, considering that the PWM pattern is center aligned and that the phase voltages must

be centered at 50% of duty cycle, it follows that the values to be loaded into the PWM output

compare registers are given respectively by:

Sector I, IV:

Sector II, V:

Sector III, VI:

4.2.4

Current sampling in three shunt topology and general purpose A/D

conversions

The three currents I1, I2, and I3 flowing through a three-phase system follow the

mathematical relation:

I1+I2+I3=0

For this reason, to reconstruct the currents flowing through a generic three-phase load, it is

sufficient to sample only two out of the three currents while the third one can be computed

by using the above relation.

The flexibility of the STR750 A/D converter trigger, makes it possible to synchronize the two

A/D conversions needed for reconstructing the current flowing through the three-phase AC

induction motor at any given time along the PWM period. To do this, the control algorithm

must have a full control of the A/D converter peripheral.

−

TimePhA

−

TimePhA

TimePhB

TimePhC

−

TimePhA

−

TimePhA

TimePhB

TimePhA

TimePhC

−

TimePhA

−

TimePhC

hTimePhB

TimePhA

TimePhC

−

UM0324 датащи(PDF) 41 Page - STMicroelectronics

UM0324 датащи(HTML) 41 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL