Protection Systems

key protection features of the motor controller and the configurable behaviours motor controller temperature protection the motor controller monitors temperature at multiple points to improve reliability and avoid depending on a single sensor it measures temperature at bridge temperature taken at the power electronics (mosfets), the primary heat source within a motor controller mcu temperature taken at the processor, located away from the bridge, to track internal heat transfer and provide a backup reading to prevent overheating, the motor controller includes configurable thermal protection you can set how the controller responds when temperature exceeds a defined limit regardless of the selected response the motor controller will stop driving once the absolute temperature limit of 135°c is reached motor controller temperature responses power ramp response the power ramp setting limits maximum output duty cycle based on bridge temperature this helps protect the controller under high thermal load two temperature setpoints define how the ramp works "over temperature limit" the ramp starts here as the bridge temperature rises above this point, the maximum duty begins to reduce " over temperature ramp end temperature" at this point, the maximum duty is reduced to the defined "over temperature duty limit" the output duty cycle decreases smoothly between these two points note the " over temperature ramp end temperature" must be higher than the "over temperature limit" for the ramp to function correctly power step response the power step setting reduces the maximum duty cycle in a single step when the "over temperature limit" is reached the size of this step is set by the "duty ramp limit" parameter by default, the maximum output duty is limited to 50% when the response is active the "ramp down rate" controls the rate at which this reduction occurs after the over temperature limit is exceeded no response output duty will not be limited past the "over temperature limit" the motor controller will shut down if the bridge reaches 125 °c, regardless of configuration clearing motor controller temperature protection response to clear the temperature protection state, there is a 5° hysteresis that is, to clear the protection state and return to normal operation, temperature must be over temperature limit 5° motor temperature you can connect a motor temperature sensor—either ntc or ptc type—to the esc this enables both motor temperature telemetry and automatic protection if the motor overheats for instructions on how to connect and configure the motor temperature sensor, see motor temperature responses limit power output the unit will actively limit maximum duty cycle to prevent the motor temperature from exceeding the set limit the unit will preemptively limit the duty cycle as the motor temperature approaches the limit set by 'motor temperature limit' the response can come into effect within 10 degrees of the set limit temperature) maximum motor duty cycle is limited all the way down to the 'motor over temperature duty limit' power step the unit will step the maximum duty cycle to the configured 'motor over temperature duty limit' when the motor temperature exceeds the limit once the motor temperature is below the limit again, the maximum duty cycle will return to 100% no response the unit will not respond to the motor temperature limit being exceeded voltage the unit includes protection against both bus over voltage and under voltage conditions over voltage protection guards against spikes above the set limit, which could damage internal components under voltage protection prevents operation at low voltages where reliable motor control can’t be guaranteed this helps avoid unexpected motor shutdowns you can set the over and under voltage limits independently if the voltage crosses either limit, the controller responds based on your configured settings voltage protection responses individual responses can be configured for under voltage and over voltage events hard shutdown response the hard shutdown response turns off motor drive and places the unit in an error state when the limit is exceeded to resume operation after the event clears, a zero throttle signal must be present on the input this requirement can be disabled using the "require zero throttle check" setting limit duty cycle output response during an over voltage event, this response limits how quickly the motor can decelerate this helps prevent further voltage spikes in the system during an under voltage event, the drive is restricted from increasing beyond its current duty cycle if the duty cycle drops to zero, the motor will stop and won’t restart until the under voltage condition clears disabled disabling the limit removes the configurable protection the units will still shut down when their absolute voltage limits are reached, which can be found on the datasheet clearing voltage protection response to clear the voltage protection state, there is a 2v hysteresis that is, to clear the protection state and return to normal operation, voltage must be undervoltage limit + 2v (to clear undervoltage) overvoltage limit 2v (to clear overvoltage) current the unit limits current at both the bus input and the phase output when current approaches the configured limit, the controller reduces the output duty cycle to keep the current within safe levels the controller also supports regenerative braking for fast motor deceleration when reducing commanded duty cycle, energy is returned back to the power source this enables quicker braking and improves the system’s transient response to protect the unit, a current limit is applied during regeneration a lower regenenerative current limit will result in slower deceleration, especially with larger loads rpm limit the rpm limit caps the maximum rotational speed of the motor this can be used for system safety, mechanical protection, or performance restrictions the rpm limit is referring to the mechanical rpm which requires the “motor pole pairs” parameter to be correctly set the default value for “motor pole pairs” is 0 if the “motor pole pairs” setting is not changed to matched the motor being used, the motor controller will not accurately report or limit the mechanical rpm