ADMC201

REV. B

–9–

Forward Park Rotation

If the input signals are represented by Vd and Vq, then the

transformation can be described by:

VX

VY

the inputs to the reverse Clarke transformation.

Forward Clarke Transformation (2- to 3-Phase)

The second operation to be applied to the above results, is the

Forward Clarke Transformation where 2-phase (stator) voltage

signals are converted to 3-phase (stator) voltage signals.

For the inverse Clarke transform we require three-phase outputs

of the form below:

PHV1

V cos

α

PHV2

V cos (

α + 120)

PHV3

V cos (

α + 240)

We have two quadrature voltages (V cos

α and V sin α) available.

PHV2

V cos (

1

2 ×

Vcos

α – 3

2 ×

V sin

α

PHV3

V cos (

1

2 ×

V cos

α+ 3

2 ×

V sin

α

PROGRAMMABLE DIGITAL INPUT/OUTPUT PORT

The ADMC201 has a six bit programmable digital I/O port.

Each bit is individually configurable as input or output. All bits

configured as inputs have the ability to operate as interrupt

sources. Each pin is independently capable of generating an in-

terrupt should its input level change.

Configuring the Programmable Digital I/O Port

The PIOCTRL register is used to configure the individual bits

on the programmable digital I/O port as either inputs or outputs

and to enable change of state interrupts. The lower six bits of

PIOCTRL control the direction (either input or output) of the

individual bits. A zero configures the corresponding bit as an

input; conversely a 1 configures the corresponding bit as an out-

put. The upper six bits of PIOCTRL are used to enable the

individual bits for use as change of state interrupt sources. A 0

disables change of state interrupt generation and a 1 enables

change of state interrupt generation. The interrupt enable for a

bit configured as an output is ignored. At power-up or

RESET,

all six bits of the digital port are configured as input and change

of state interrupt generation is disabled.

Using the Programmable Digital I/O Port

The PIODATA register is used to write to and read from the

digital I/O port. Bits 0–5 of the PIODATA register correspond

to PIO 0–5 on the ADMC201. Bits 6–11 of PIODATA are un-

used and always contain 0. Read from PIODATA to determine

the state of PIO 0–5. Write to PIODATA to change the states

of PIO 0–5. Writing to bits configured as input has no effect.

Reading from bits configured as output will return the last value

written.

Reverse Clarke Transformation

The first operation is the Clarke transformation in which the

represent the equivalent currents in a two-phase ac machine and

is the signal format required for the Park rotation. The three-

phase input signals are of the form:

PHIP1

θ

PHIP2

θ + 120)

PHIP3

θ + 240)

θ and

This is calculated from:

IY

3

phase input current information.

In the case where 2- of 3-phase information (PHIP2/3 only) is

provided, then PHIP1 will be derived from the simple fact that

all sum to zero. This value is then placed in the IX register.

Reverse Park Rotation

IX/IY are then processed together with the digital angle

ρ

then the rotation can be described by:

ID

IQ

where ID and IQ are the outputs of the Park rotation.

Cos

ρ and sin ρ are required for the Park rotation, and are calcu-

lated internally.

ID

IQ

Performing a Forward Transformation

In order to perform a forward rotation, write values to the VD

and VQ registers and then initiate the transformation by writing

the rotation angle to the register RHOP. The forward transfor-

mation will only operate correctly when Bit 10 in the SYSCTRL

register is set (i.e., in 3/3 mode).

The forward rotation will be completed in 40 system clock

cycles after the rotation is initiated. If Bit 6 of the system

control register is set, then an interrupt will be generated on

completion. When an interrupt occurs, the user must check Bit

1 of the system status register, SYSSTAT, to determine if the

vector transformation block was the source of the interrupt.

During the vector transformation, the transformation registers

must not be written to or the vector rotation results will be invalid.