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PWM MANAGEMENT FOR 3-PHASE BLDC MOTOR DRIVES USING THE ST7MC

Figure 1. ST7FMC Microcontroller with a three-phase bridge

1 MOTOR CONTROL MACROCELL INTRODUCTION

Figure 2 below gives a detailed view of the motor control macrocell included in the ST7MC mi-

crocontroller. In bold are the parts of the macrocell that are going to be described in this appli-

cation note and that have a role in the PWM management. The purpose of this document is to

ease the understanding of the PWM management with the ST7MC to control a brushless 3-

phase DC motor and to make this explanation easier, the schematic on the figure below can

be taken as a reference of a global view of the mechanism. Besides the drawings of the func-

tionalities, the names of the registers involved and often even the bits are written in this sche-

matic. Anyhow, each time a register is discussed in this document, either a reference or an

exact description will be made for that register.

C

A

B

HV

T4

T1

T0

T3

T2

T5

D0

D2

D4

D3

D5

D1

Low

Side

outputs

High

Side

outputs

ST7FMC

Rotor

position

inputs

M

5V

Feedback

Level

shifter