Curtis Instruments AC F4-A User Manual

3 — APPLICATION-SPECIFIC FEATURES
Curtis AC F4-A Motor Controller – August 2020 Return to TOC
pg. 26
VOLTAGE LIMITS
e F-series controllers have both hardware and parameter based voltage limits. During regenerative
braking, the system voltage increases as the motor acts like a generator to slow the vehicle. e
overvoltage protection cuts back the regenerative braking (regen) to prevent damage to the traction
battery and other electrical system components due to the increased voltage once it is above the
normal-voltage region. is typically occurs when the traction-battery is near full charge than when it
is near its discharged voltage. Conversely, as the traction-battery nears depletion, strong acceleration
or load demands can lower the battery voltage. To prevent the controller from operating below its full
capabilities, the undervoltage protection will reduce the drive current when the voltage is below the
normal-voltage region. Both of these protection methods help to prevent vehicles and systems from
operating at voltages above and below their design or the application’s thresholds. Understanding the
voltage limit regions will aid in setting the battery and speed controller related parameters.
e following conditions dene the standard F-series operating voltage ranges.
Condition Operating Voltages
Severe over-voltage 150% of maximum nominal rating
1
Over-Voltage 125% of maximum nominal rating
1
Under-voltage 50% of maximum nominal rating
Severe under-voltage 40% of maximum nominal rating
Brownout 33% of maximum nominal rating
e F4-A voltage ranges, based upon model voltage, are in the table below
2
.
Nominal
Battery
Voltage
Brownout
(Volts)
Severe
Under-voltage
(Volts)
Under-voltage
(Volts)
Over-voltage
(Volts)
Severe
Over-voltage
(Volts)
24 8 9.6 12 33 36
36-48 12 14.4 18 63 72
When the supply voltage is within the normal operation zone, the controllers operate with their full
current and features. To narrow the normal operating window, for example to tailor an application
to work with a more restrictive battery, change the User Overvoltage and Undervoltage parameters.
Condition
User/Parameter Defined
(Application Setup/Battery Setup/…Under and Overvoltage parameters)
Over-Voltage Either the Maximum Voltage (F4-A voltage-range table, above), or
User_Overvoltage × Nominal _Voltage, whichever is lower.
Under-voltage Either the Minimum Voltage (F4-A voltage-range table, above) or
User_Undervoltage × Nominal_Voltage, whichever is higher.
1
There are slightly higher over-voltage limits for the 24V, 36V and 48V models than in the table’s definitions. See the model table.
2
See Appendix E for the models and specifications. See the AC F4-A datasheet, available on the Curtis website, for new
model updates.

Curtis Instruments AC F4-A Specifications

General

Brand	Curtis Instruments
Model	AC F4-A
Category	Controller
Language	English