MC1451 データシートの表示（PDF） - PMD

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MC1451

Advanced Brushless Motor Control Chipset

PMD 

Theory of Operations

Incremental Encoder

Index Home

B

1/a

1/a 1/a

I/O Chip

Internal Block Diagram

A

1/a

PWM mag.

1/phase

Motor Output

DAC address

2

DAC data

16

DAC, PWM signal generator (6 channels)

CP Chip

Commutation

Generator (2)

Index capture

register (2)

Quadrature

decoder

counter (2)

Position

register (2)

Digital Servo

filtering (2)

Trajectory profile

generator (2)

System Registers (2)

Host I/O controller

5

Control

8

Data

1

host interrupt

Host command

1/a

1/a

PosLimit NegLimit

The above figure shows an internal block diagram for the MC1231A

motion processor.

Each servo axis inputs the actual location of the axis using incremental

encoder signals. These encoder signals are digitally filtered for

increased reliability and then passed on to a high speed up/down

counter. This counter is used to maintain a 32-bit actual axis position

register.

The chipset can be operated in two modes. Closed loop mode, which is

the normal operating mode of the chipset, performs trajectory

generation, digital servo loop closure, and sinusoidal commutation. In

this mode the motor output value is controlled by the servo filter. Open

loop mode performs commutation only. It allows the motor output value

to be controlled directly by the host processor.

For either operating mode the desired motor output value is then

combined with the current commutation value from an internal

sinusoidal lookup. The commutation angle is determined using the

motor encoder. Two or more commutated signals are generated for

each axis, with each signal being shifted either 90 or 120 degrees from

one another, depending on the motor type.

The resultant commutated signals are then output to the amplifier either

as PWM or DAC signals.

To perform continuous digital servoing, the trajectory and servo

calculations are performed at every sample time for all enabled axes.

The commutation is performed 4 times for each sample time.

The following table summarizes the operational parameters of the

MC1231A-series chipsets.

17

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