Virtual current control loop on the Q1, Q2 channels of Root Part Number 1

AN2791

14/18

Similar results have been observed considering another operative condition, characterized

by a different duty-cycle strategy (see Table 3). Clearly, the duty-cycle applied on the

unregulated channels in both the operative conditions under test is the same measured on

the regulated channel. See columns 2, 3 of the following tables to understand the difference

between the two duty-cycles applied on the unregulated and regulated channels of the

L9352B on the same load conditions.

As second operative condition for our tests (see Figure 9) we can refer to the following data:

●

INLET valve opening/closing frequency of 1 Hz

●

for the first 500 ms, duty-cycle = 0.1 %

●

for the last 500 ms, duty-cycle = [15:10:75] %

The Table 2 and 3 show the results of a comparison between the mean current on the loads

driven by the regulated channels of Root Part Number 1 and the unregulated ones. These

last have been trained on the output duty-cycle of the regulated channels.

Just to highlight the results obtained by this analysis, it is important to summarize the

difference in the coil current of the unregulated channels of Root Part Number 1 before and

Table 2.

Results of the first operative condition under test

Input duty

(hold phase)

Unreg. ch.

output duty

(before the

manual

regulation)

Reg. ch.

output duty

Unreg. ch.

mean current

[mA]

Unreg. ch.

pk-to-pk

current [mA]

Reg. ch.

mean current

[mA]

Reg. ch.

pk-to-pk

current [mA]

0.15

0.83

0.75

520

280

390

360

0.25

0.73

0.65

749

360

660

360

0.35

0.64

0.53

990

400

920

480

0.45

0.55

0.41

1200

480

1200

480

0.55

0.44

0.26

1480

480

1480

480

0.65

0.35

0.1

1700

480

1740

440

0.75

0.23

0.09

1780

520

1760

480

Table 3.

Results of the second operative condition under test

Input duty

(hold phase)

Unreg. ch.

output duty

(before the

manual

regulation)

Reg. ch.

output duty

Unreg. ch.

mean current

[mA]

Unreg. ch.

pk-to-pk

current [mA]

Reg. ch.

mean current

[mA]

Reg. ch.

pk-to-pk

current [mA]

0.15

0.83

0.75

530

320

390

360

0.25

0.73

0.65

780

400

660

360

0.35

0.64

0.53

980

440

920

440

0.45

0.53

0.39

1240

480

1200

480

0.55

0.44

0.25

1460

560

1480

520

0.65

0.34

0.09

1630

440

1740

480

0.75

0.25

0.09

1630

440

1820

480