A new petition has been filed with the Office of Defects Investigation (ODI) requesting a reevaluation of the denial to investigate sudden unintended acceleration (SUA) in Tesla vehicles. The petition suggests that a faulty inverter design could be causing negative spikes in the low-voltage system, which can be misinterpreted as a full acceleration command.
The person behind the new petition, Ronald A. Belt from Plymouth, Minnesota, suggests this design flaw could explain the reports of Tesla vehicles accelerating without the driver touching the accelerator pedal.
According to Belt intermittent high electrical current demands on the vehicles’ 12VDC systems may have caused the incidents examined in the previous investigation by the NHTSA. The inverter, which uses a voltage reference derived from the 12-volt system to calibrate the accelerator pedal position, may produce incorrect calibration voltages that lead to sudden unintended acceleration. Belt says this explains why the vehicle logs show the accelerator pedal was pressed down even when drivers claimed not to have touched it.
The lengthy petition, first reported by autoevolution, identifies the cause of the negative spikes in the low-voltage system as the high current motor used by the steering assist system. When the motor requires over 100 amps to turn the wheels while the vehicle is stationary, the 12-volt system experiences a voltage drop to near zero volts. If a recalibration occurs during this interval, an incorrect calibration voltage close to zero volts can be produced, leading to a spike equivalent to pressing the accelerator pedal down.
According to Belt he was able to verify his theory by intentionally inputting the wrong calibration voltage into the inverter, causing sudden unintended acceleration without the driver pressing the accelerator pedal. Two solutions are proposed to address the issue: adding a second 12-volt supply line for powering the accelerator pedal position sensors and analog-to-digital converters, or modifying the calibration routine software to test the calibration voltage before use.
You can read the full petition below.breaking-nhtsa-petition-shows-tesla-s-sudden-unintended-acceleration-is-real-and-curable-217525