Protection - Renesas MCI-HV-1 User Manual

MCI-HV-1 User's Manual

4.4 Protection

4.4.1 Inrush current protection
This circuit prevents inrush current at AC power on. Note that the function does not work when DC input is
used.
When the signal "RELAY_IN" is LOW, the relay (U1) is turned off and the bus voltage is charged through the
thermistor (R3).
When "RELAY_IN" is HIGH, the relay (U1) is turned on.
User should control "RELAY_IN" to be LOW at the startup and to be HIGH after charging up the bus voltage.
"RELAY_IN" is input from pin 15 of CN9.
4.4.2 Over temperature detection
If the temperature of the IGBT module (U9) exceeds 90°C or the temperature around the PFC coil
exceeds 76.9°C, the THERMAL_ERROR signal falls to LOW. Therefore, if you want to protect against
overheating, detect the THERMAL_ERROR signal on pin 17 of CN9 with the CPU board and stop the
inverter operation, etc.
4.4.3 Overvoltage detection
When the bus voltage (VBUS) becomes higher than 437V, control signal RES_ON_G rises and
MOSFET Q5 turns on. Once RES_ON_G rises, it only falls when VBUS becomes lower than 426V.
By installing an external regenerative absorption resistor on CN4, it is possible to suppress the VBUS
from rising above 437V.
For example, attach a metal-clad resistor with a resistance value of 100 Ω or more/power rating of 200
W, etc.
Avoid attaching resistors of less than 100Ω. The internal absorption circuit may be damaged.
When decelerating from high speed operation, the regenerative absorption resistor must dissipate heat
sufficiently, and it must be confirmed that the heat generated by the resistor is within the allowable range.
Note that a brake resistor is not included in this product and must be installed by the user if overvoltage
during motor deceleration and so on is to be prevented.
VDC_RES
R12UZ0138EJ0100 Rev.1.00
February 28, 2024
15V
U1
R3
Fig. 4-7 Inrush current protection circuit
5V
5V
30k
1.8k
10k 10k
1.8k
GND
5V
4.7k
510
GND
Fig. 4-8 Over voltage detection
RELAY_IN
GND
GND
U7
INA OUTA RES_ON_G
INB OUTB BLEED
VBUS
CN4
Q5
150
RES_ON_G
10k
PGND
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