Electric Machine Blockage Detection via Torque Actuation
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Solution Overview
Problem
Conventional control units in electric vehicles are unable to reliably detect blockages in electric machines, leading to potential damage and unsafe driving situations due to incorrect actuation, as they cannot differentiate between mechanical blockages and external influences.
Innovation Solution
A method involving continuous monitoring of the electric machine's rotational speed, with selective actuation to increase torque and brief interval measurements to distinguish between intact and blocked states, using a control unit that can deactivate averaging provisions to detect brief rotational speed increases, and optionally utilizing a clutch for decoupling to diagnose drive train faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional control units continuously monitor rotational speed and ignore brief fluctuations to maintain stable control, then control stability is improved, but the ability to detect brief blockage events is lost
Solution Approach 1:
The control unit dynamically adjusts its monitoring behavior based on operational context. During normal operation, it averages rotational speed values over a time period to filter fluctuations. Upon detecting a blocked state (when rotational speed drops to zero or near-zero), it temporarily deactivates the averaging provision and switches to immediate response mode, allowing detection of brief blockage events that would otherwise be filtered out.
Solution Approach 2:
The system changes the parameter of rotational speed measurement processing from averaged values to immediate values when a blocked state is detected. This parameter change allows the system to respond to brief blockage events while maintaining stable control during normal operation, effectively resolving the contradiction between stability and detection reliability.
2Power
If the control unit increases power supply to the electric machine to overcome external influences, then driving capability is improved, but false indication of blockage occurs
Solution Approach 1:
The control unit performs a preliminary test by briefly increasing power supply to the electric machine when a blocked state is detected. This preliminary action serves to differentiate between true mechanical blockages and external influences such as obstacles or坡度. If the rotational speed increases in response to the power increase, the system determines it is not truly blocked and can resume normal operation.
Solution Approach 2:
The system uses feedback from the rotational speed response to the increased power supply to determine whether a blockage is real or false. By monitoring whether the rotational speed increases when power is increased, the control unit can distinguish between mechanical blockages (no speed increase) and external influences (speed increase), thereby improving blockage detection accuracy.
3Reliability
If additional technical means are added to detect blockage, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The control unit performs multiple functions using existing components: it controls the electric machine, monitors rotational speed, detects blocked states, and differentiates between true blockages and external influences. By making the control unit multi-functional, the system achieves reliable blockage detection without adding separate dedicated detection devices, thereby avoiding increased complexity.
Solution Approach 2:
The control unit uses its own existing resources (power supply capability, rotational speed monitoring, and control algorithms) to detect and diagnose blockage conditions. The system serves itself by utilizing its control authority over the electric machine to perform diagnostic functions, eliminating the need for additional specialized detection equipment.
Data Source
AI summary
The invention relates to a method and a control unit, which makes it possible to reliably detect in an electric vehicle whether or not an electric machine is in a blocked state. For this purpose, a current rotational speed of the electric machine (1) is monitored using a control unit (7). If a non-rotating state is detected, the electric machine (1) is actuated specifically for increasing a torque. The current rotational speed is further monitored, in particular for an increase of the current rotational speed of the electric machine, at least a short-term one, for tensioning a drive train (3) against a wheel (5) blocked due to external influences, for example. If this is not the case, it is assumed that the electric machine (1) is blocked, and a corresponding blocking signal is generated. If the electric machine (1) is detachably connected to the wheel (5) via a coupling (19), it can be additionally provided that once the non-rotating state is detected, the coupling (19) is disengaged in order to see if the electric machine (1) will react to a request for an increased torque with an increased rotational speed, or if this does not happen due to a blocked electric machine.