MP6546

– 22V, 3A PEAK, 3-PHASE BLDC DRIVER WITH 1MHZ I2C INTERFACE

MP6546 Rev. 1.0

MonolithicPower.com

12

3/20/2023

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Internal Angle Processing

Theta Bias, Direction and Pole Pairs

The MP6546 supports a biased angle setting to

align the

sensor angle’s zero position with phase

A’s

axis.

This

bias

can

be

set

via

THETA_BIAS[11:0] in register 02h.

The angle direction can be corrected by the

THETA_DIR bit in register 00h if the desired

rotation direction is opposite of the sensor angle.

The MP6546 supports up to 15 pairs of motor

poles, which can be set via POLE_PAIR[3:0] in

register 02h.

Theta Filter

The MP6546 supports two type of angle low-

pass filters. The first filter is used for internal

space vector PWM (SVPWM) control. Select the

bandwidth frequency via FLT_N_SVM[2:0] in

register 00h. The second filter is provided for the

system

’s angle output. In this scenario, select

the bandwidth frequency via FLT_N[1:0] in

register 00h, and obtain the angle value by

reading ANGLE[14:0].

INL Correction

The MP6546 supports an INL correction function

to compensate for the angle error caused by the

nonlinear factors. The INL error in one cycle is

divided to 32 segments, which are configured by

registers

INL_00[5:0]~INL_1F[5:0]

(registers

13h~1Eh). Each segment can cover an INL error

of up to 22.4° (see Figure 6).

INL_00[5:0]

INL_01[5:0]

INL_02[5:0]

…

Reference

0°

360°

Sensor

Error

Angle

Figure 6: Sensor INL Calibration

INLxx[5:0] can be estimated with Equation (2):













+







=

0

θ

,

2

0.35

θ

0

θ

,

0.35

θ

0]

:

INL_xx[5

INL

6

INL

INL

INL

(2)

Where θINL is INL error (in °), and INL_xx[5:0] is

the correction value represented by a signed

number of 6 bits.

For example, i

f θINL is -5°, then set INL_xx[5:0] to

0x32.

The INL compensation for the current position

can be obtained via INL_COMP[7:0] in register

0Dh.

Drive Mode

The MP6546 supports two inverter drive modes:

vector control mode and duty control mode.

Select the control mode via the DRV_MOD bit in

register 00h.

Vector Control Mode

In vector control mode, UD[9:0] (in register 08h)

and UQ[9:0] (in register 09h) must be set, and

the angle that is used for IPARK coordinate

transformation can come from either the external

sensor or ANGLE_T[11:0] in register 07h. Use

the ALN_MOD bit in register 0Ah to select the

angle source.

UD[9:0] and UQ[9:0] can be calculated with

Equation (3) and Equation (4), respectively:















+



=

0

ud

,

2

V

ud

3

512

0

ud

,

V

ud

3

512

0]

:

UD[9

10

IN

IN

(3)















+



=

0

uq

,

2

V

uq

3

512

0

uq

,

V

uq

3

512

0]

:

UQ[9

10

IN

IN

(4)

Where UD is d-axis voltage, UQ is q-axis

voltage, and VIN is the bus input voltage.

Duty Control Mode

Set DRV_MOD in register 00h to 1 for duty

control mode. In this mode, the duty of the

inverter’s three-phase output is determined via

registers 07h, 08h, and 09h, respectively.

As PWMx[8:0] (where x = A, B, or C) changes

from 0x100 to 0x1FF, the voltage duty changes

from 100% to 0%. Reset the ninth bit of

PWMx[8:0] (PWMx[8]) to shut down the output of