Rotary Electric Machine Torque Cut-Off Control
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Solution Overview
Problem
Existing rotating electrical machines experience torque surges and overvoltages on the on-board network when switching elements open during mode transitions, particularly during engine start-up and shutdown, leading to inefficiencies and potential damage.
Innovation Solution
A method for controlling the rotating electrical machine involves setting a setpoint torque to zero and a predetermined torque gradient, which is adjusted based on the machine's rotational speed, to manage the transition from motor mode to idle, thereby reducing current draw and preventing torque surges and overvoltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching elements of the inverter are opened to stop the motor mode, then the motor mode is effectively stopped, but torque surges and overvoltages occur on the on-board network
Solution Approach 1:
The control module applies a predetermined negative torque gradient before the switching elements are fully opened to preemptively reduce the current in the stator. This preliminary action prevents the sudden current reversal that causes torque surges and overvoltages, while still achieving effective motor mode stopping.
Solution Approach 2:
The control module changes the torque parameter from a positive setpoint to a predetermined negative gradient during the transition phase. This parameter change allows continuous control of the electric machine to manage current decay, preventing harmful torque surges and overvoltages when switching elements open.
2Productivity
If the switching elements open suddenly to stop motor mode, then the mode transition is achieved, but current in the stator is sent back to the on-board network causing overvoltage
Solution Approach 1:
The control module preemptively applies a negative torque gradient to reduce stator current before the switching elements fully open. This preliminary current reduction prevents the harmful current reversal and overvoltage on the on-board network, while maintaining efficient mode transition.
Solution Approach 2:
The control module acts as an intermediary between the motor mode activation request and the switching element operation. It introduces a controlled current reduction phase using a predetermined torque gradient, mediating the transition to prevent sudden current reversal and overvoltage on the electrical network.
3Reliability
If a predetermined torque gradient is applied to reduce current before switching elements open, then torque surges and overvoltages are avoided, but the control complexity increases
Solution Approach 1:
The control module uses a predetermined torque gradient parameter that is stored and automatically applied when motor mode stop is requested. This parameter-based approach provides a simple yet effective control strategy to prevent torque surges and overvoltages without requiring complex control algorithms or additional hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively minimizes torque surges and overvoltages on the on-board network, ensuring smooth transitions and reducing energy consumption during mode changes, thus enhancing the operational reliability and efficiency of the electrical machine.
Implementation Method 1
a rotating electrical machine (10) for a motor vehicle, comprising a stator (18) and a rotor (19), the rotating electrical machine comprising a control module (14) capable of generating a stator command and a rotor command from a torque and a torque gradient to be applied to the rotating electrical machine
Data Source
Figure 1~2
Figure 3
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AI summary
The invention relates to a method for controlling a rotary electric machine (10) for a vehicle comprising a stator (18) and a rotor (19), the machine comprising a control module (14) able to generate a stator command (Comm_stat) from a torque and a torque gradient to be applied to the electric machine (10), characterized in that: - following a demand to activate a drive mode of the electric machine (10),the method comprises a step of applying a setpoint torque (T_cons_ecu) and a setpoint torque gradient (G_cons_ecu) transmitted by a motor control computer, and - following a demand to stop the motor mode previously activated and independently of the torque (T_cons_ecu) and of the torque gradient (G_cons_ecu) required by the computer (15), said method comprises a step of applying to the electric machine (10) a zero setpoint torque (T_cons_mel) and a predetermined torque gradient (G_cons_mel).