Everest CORE - Product Manual |
Application Guide
INGENIA | 08/01/2019
31
Signals description
Signal
Description
POW_SUP
Input from power supply
SUP_PROTECTED Protected power supply. To be connected to power pin 1 of P1 in Everest CORE
GND_P
Power supply reference voltage. To be connected to power pin 2 of P1 in Everest CORE
Design Notes
•
In this circuit, the P-channel MOSFET is only polarised properly when the polarity of the supply is correct
thanks to resistors R1 and R2. Diode D1 ensures that the maximum gate voltage of the transistor is not
exceeded.
•
Note that the transistor orientation intentionally allows conduction through the body diode if the supply is
polarised properly.
Bill of materials
Designator Part Number
Manufacturer Package
Value / Description
D1
PDZ12B,115
NXP
SOD-323
Diode Zener 12 V, 400 mW, 2% tolerance
Q1
SUM70101EL-GE3 Vishay
TO-263 /
D
2
PAK
P-channel MOSFET, 100 V, 120 A
R1, R2
RMCF0402FT100K Stackpole
0402
Thick film resistor, 100 k
Ω
, 1 % tolerance, 1/16
W
Shunt Braking Resistor Transistor
During operation the motor normally consumes the energy provided by the drive, but in specific situations this
roles change and the motor behaves as a generator. This would happen during short periods of time when the
motor is commanded to rapidly decelerate or even change its direction of rotation, or during longer periods of time
when the load is driving the motor, like it would happen when a hoist is overloaded. In this cases, although an
inverter typically works as a "step-down", it will behave as a "step-up", and could elevate the voltage of the internal
DC bus even beyond its maximum ratings, causing permanent damage to the drive and leaving the load completely
uncontrolled.
Therefore, this is an over-voltage protection.
To get rid of the problem, 4 strategies are considered. The best one to follow would mostly
depend on the
dynamics of the load
, so there is not a best solution to frame all the possible scenarios.
•
Not doing anything:
re-injection could not be an issue, specially when the nominal voltage of the motor is
way smaller than the one of the drive (i.e. driving a 24 V motor with Everest CORE). If the re-injection is not
too strong, the internal DC bus of the drive will increase, but not enough to reach dangerous levels, so the
drive will simply withstand it.
•
Using the DC bus capacitors:
if a large bulk capacity is installed close to the Everest CORE (not long wires
between them) when the DC bus voltage increases because of a re-injection, the capacitors will store the
energy, and slowly deliver it afterwards to the motor during normal operation. This method is tremendously
ineffective compared to dissipating the excess of energy, but it could do the job in front of short and fast re-
injections that would not happen very often, like when the motor sporadically has to change direction of
rotation .
