Renesas RL78/G1F User Manual page 14

RL78/G1F Motor Driver Board GB01
8.2 Current Detection Circuit
The current detection circuit is integrated to measure the U-phase, V-phase, and W-phase current. The
current detection circuit is configured by mounting a shunt resistor for the U-phase, V-phase, and W-phase.
The voltage drop generated when the current passes through the shunt resistor is amplified by the
operational amplifier and then input to the microcontroller. The equation (1) below shows the relationship
between the current Iin running through the shunt resistor and the voltage Vout input to the microcontroller.
Figure 8-2 Schematic Diagram of Current Detection Circuit
Also, a DC link shunt resistor is mounted for 1-shunt current detection, which enables detection of the
overcurrent by using the RL78/G1F internal PGA and current detection comparator.
Figure 8-3 Connection of PGA and Inverter Control Circuit
Figure 8-4 Overcurrent Detection Using Internal PGA and CMP0
R12UT0012EJ0100 Rev.1.00
20.10.2020
Vout[V] = Iin[A] × Rs[Ω] × 5 + 2.5 (1)
20k Ω
2.0k Ω
Rs
Iin
2.0k Ω
20k Ω
Rs : Shunt resistance
Iin : Current flowing through the shunt resistor
Vout : Voltage applied to CPU card connection terminal
DC POWER
INPUT
Idc
5V
+
-
Vout
10k Ω
Inverter
circuit
PGA
PGAGND
-
+
PGAIN
+
-
D/A
Converter
User's Manual
I _OPA
U
I _OPA
V
I _OPA
W
A/D Converter
CMP0
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