OM9373SF Просмотр технического описания (PDF) - International Rectifier

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OM9373SF

FULL-FEATURED POWER MODULE FOR DIRECT DRIVE OF 3-PHASE BRUSHLESS DC MOTOR

International Rectifier 

OM9373

Modes of Operation

Figures 2 and 3, shown on the following pages,

provides schematic representations of typical voltage-

mode and current -mode applications for the OM9373

controller/driver.

Figure 2 represents the implemenation of a typical

voltage-mode controller for velocity control. A voltage

or speed command is applied to the noninverting

input of the error amplifier which is configured as

voltage follower. The ouput of the error amplifier is

compared to a pulse width modulated ramp,and

since motor speed is nearly proportional to the

average phase output voltage, the average speed is

controlled via duty cycle control. If a speed feedback

loop is required, the tachometer output can be

connected to the inverting input of the error amplifier

via a loop compensation network.

Figure 2 also shows the implementation of the

cycle-by-cycle current limit/overcurrent protection

feature of the OM9373. The load current is monitored

red via the controller’s internal sense resistor. The

current sense signal is filtered and fed into the current

rent sense amplifier where the absolute value of

ISH-ISL is multiplied by two and biased up by 2.5V

The output of the current sensor amplifier is compared to

a fixed reference, thus providing cycle-by-cycle

current limiting and/or overcurrent protection as

necessary. The typical peak current threshold (ISL-ISH)

is 0.2V; the typical over current threshold (ISH-ISL) is

0.3V.

Fig 2: Implementation of a Voltage -Mode Controller

+15V

3.24k

COMMAND

1k

1.50k

FROM MOTOR HALL SENSORS

H3

H2

H1

10uF +

.1uF

.1uF

10k

.1uF

4700pF

232

232

1

2 Vcc

EA1-

3

4 EA2+

5 EA1+

6 VREF

7 EA2-

8 EA2_OUT

9 EA1_OUT

10 PWM_IN

11 OSCILLATOR

12 I_SENSE

13 ISH

ISL

14

15 QUAD_SEL

16 TACH_OUT

17 BRAKE

18 OV_COAST

19 SOFT_START

20 GROUND

21 H3_HALL_INPUT

22 H2_HALL_INPUT

23 H1_HALL_INPUT

24 SPEED_IN

25 DIRECTION

26 CSH

CSL

43

V_MOTOR

42

PHASE_A_OUT 41

PHASE_A_OUT

40

SOURCE_A 39

SOURCE_A

38

V_MOTOR

37

PHASE_B_OUT 36

PHASE_B_OUT

35

SOURCE_B 34

SOURCE_B

33

V_MOTOR

32

PHASE_C_OUT 31

PHASE_C_OUT

30

N/C 29

SOURCE_C

28

MOTOR_RETURN 27

MOTOR_RETURN

V_MOTOR

C_BUS

+

C_FILT

MOTOR

H1

H2

H3

HALL SENSORS

6

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