Reconfigurable EV Drive Motor Control for Torque Hole Avoidance
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Solution Overview
Problem
Existing drive systems for hybrid or electric vehicles face limitations in power delivery continuity and experience torque/power holes during acceleration due to abrupt transitions between motor configurations, compromising safety and driving comfort.
Innovation Solution
A drive system comprising a reconfigurable synchronous electric machine with an inverter and control unit that selectively switches between electrical configurations, optimizing power delivery by controlling flux weakening and adjusting the number of conductors in series to minimize torque holes and ensure continuous power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stator windings are reconfigured when knee speed is reached, then safety is improved by avoiding uncontrolled generator operation, but delivery fluidity deteriorates due to significant torque/power holes during acceleration
Solution Approach 1:
The control unit performs preliminary flux weakening action before the knee speed is reached, preparing the magnetic flux for the upcoming configuration change. This preliminary preparation ensures that when the stator windings are reconfigured at knee speed, the transition occurs smoothly without torque holes, thus maintaining both safety and delivery fluidity
Solution Approach 2:
The system changes the magnetic flux parameter dynamically by controlling the inverter to weaken flux before configuration switching. This parameter change allows the electric machine to adapt to the new stator winding configuration smoothly, avoiding abrupt torque variations while maintaining safe operation boundaries
2Ease of manufacture
If the electric machine operates in a fixed configuration, then manufacturing simplicity is maintained, but adaptability deteriorates due to limited efficiency range
Solution Approach 1:
The system introduces dynamic reconfigurability to the stator windings through switching devices controlled by the control unit. This allows the electric machine to adapt its configuration dynamically based on operating conditions, extending the efficiency range while maintaining a relatively simple manufacturing process using standard electrical switching components
Solution Approach 2:
The electric machine is designed with multi-functional capability through reconfigurable stator windings that can operate in different configurations. This allows a single machine design to serve multiple operating conditions and efficiency ranges, effectively making it universal across various driving scenarios without requiring multiple specialized machines
3Loss of time
If abrupt configuration switching is performed, then response time is improved by quickly adapting to operating conditions, but power delivery continuity deteriorates due to torque holes
Solution Approach 1:
The control unit executes preliminary flux weakening before the configuration switch, preparing the magnetic field in advance. This preliminary action reduces the impact of the upcoming configuration change, enabling fast switching without creating torque holes, thus maintaining both quick response time and continuous power delivery
Solution Approach 2:
The control unit acts as an intermediary that coordinates the timing and manner of configuration switching. It manages the transition process by controlling the inverter's flux weakening action, ensuring that the switching occurs at the optimal moment (when knee speed is reached) with proper preparation, thereby maintaining power delivery continuity while achieving fast adaptation
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
The system achieves high-performance, safe, and continuous power delivery by smoothly transitioning between motor configurations, mimicking automatic transmission without torque holes, thereby enhancing driving comfort and safety.
Implementation Method 1
an electric machine, preferably of the synchronous type (magnets or reluctance), and equipped with a rotor rotating around its own rotation axis and a stator containing a plurality of phases
Implementation Method 2
a switching device selectively switchable between a first configuration, in which the stator phases are in a first electrical configuration, and a second configuration, in which the stator phases are in a second electrical configuration
Implementation Method 3
the control unit is configured to: drive the adjusting device so as to control the electric machine in flux weakening mode when the rotation speed of said rotor is higher than said first knee speed
Data Source
AI summary
A drive system for a hybrid or electric vehicle includes an electrical energy source; an electric machine, a switching device linked to the electric machine and selectively switchable between a first configuration, and a second configuration, an adjusting device linked to the electric machine and configured to vary its operating parameters, and a control unit. The first electrical configuration includes a first number of conductors in series by phase supplying a first driving torque with a first knee speed and a first no-load operation speed. The second electrical configuration includes a second number of conductors in series by phase supplying a second driving torque, lower than the first driving torque, and a second knee speed higher than the first knee speed. A ratio between the first no-load operation speed and the second knee speed is between 0.7 and 1.3.