UM0324 datasheet(43/105 Pages) STMICROELECTRONICS

tên linh kiện	UM0324

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UM0324

Library functions

43/105

Figure 22.

Three shunt topology current sampling and GP A/D conversions

integration (REP_RATE=1)

4.2.5

Tuning delay parameters and sampling stator currents in three shunt

resistor topology

Figure 23 shows one of the three inverter legs with the related shunt resistor:

Figure 23.

Inverter leg and shunt resistor position

To indirectly measure the phase current I, it is possible to read the voltage V providing that

the current flows through the shunt resistor R.

It is possible to demonstrate that, whatever the direction of current I, it always flows through

the resistor R if transistor T2 is switched on and T1 is switched off. This implies that in order

to properly reconstruct the current flowing through one of the inverter legs, it is necessary to

properly synchronize the conversion start with the generated PWM signals. This also means

that current reading cannot be performed on a phase where the duty cycle applied to the low

side transistor is either null or very short.

UM0324 bảng dữ liệu(PDF) 43 Page - STMicroelectronics