EV Drive Control with Staggered Pole and Battery Switching
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Solution Overview
Problem
Electric vehicles without transmissions face discomfort for drivers accustomed to engine vehicles due to inadequate acceleration performance and instability when using existing rotary electric machine controllers that only change the motor's pole number after a predetermined speed is reached, leading to unsatisfactory driving experiences.
Innovation Solution
A vehicle drive system that includes a motor with a cylindrical stator and rotor, and a battery system with modular configurations, where the motor control section and battery control section initiate changes in the number of poles and battery connection modes at different timings to stabilize the system and provide a wide range of output preferences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple methods for changing motor characteristic (voltage control, current control, pole number control) are executed simultaneously, then a wide range of output is achieved, but the vehicle system becomes unstable due to rapid state change
Solution Approach 1:
The control method determines the required output first, then selects and executes only the necessary control method in advance, avoiding simultaneous execution of multiple methods. This preliminary determination prevents rapid state changes while achieving the required output range through selective application of voltage control, current control, or pole number control.
2Device complexity
If the rotary electric machine controller changes the number of poles only when motor rotation speed exceeds a predetermined value, then the controller is simple, but it cannot completely solve the driving feeling discomfort for drivers accustomed to engine vehicles
Solution Approach 1:
The control method dynamically selects among multiple control strategies (voltage control, current control, pole number control) based on real-time operating conditions and required output. This dynamic adaptation allows the system to provide appropriate driving feeling across different speed ranges while maintaining reasonable controller complexity through systematic decision-making.
3Speed
If the motor rotation speed is increased proportionally with vehicle speed, then favorable acceleration performance is achieved, but the driver feels like riding a go-cart which causes discomfort
Solution Approach 1:
The control method changes multiple parameters (voltage, current, pole number) in a coordinated manner based on the required output and operating conditions. By adjusting these parameters differently from simple proportional control, the system achieves favorable acceleration performance while creating a driving feeling more similar to traditional engine vehicles, thereby improving driver comfort.
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 effectively changes the motor's characteristics to mimic the driving experience of engine vehicles, enhancing acceleration and stability by coordinating pole number changes and battery mode shifts, thus improving driver comfort and system stability.
Implementation Method 1
the motor control section changes the number of poles of the stator by changing a direction of a current flowing through the plural primary conductors in the motor
Implementation Method 2
a battery that supplies electric power to the motor
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
[Task] To provide a vehicle drive system capable of changing a characteristic of a motor while suppressing a vehicle system from becoming unstable. [Solution] The vehicle drive system includes: a motor having a stator and a rotor; and a battery. The stator has plural primary conductors, the rotor has plural secondary conductors, and the battery has plural battery modules. A motor ECU and a battery ECU are provided. The motor ECU can change the number of poles of the motor by increasing/reducing the number of primary conductor groups, in each of which a current flows in the same direction and the primary conductors are continuously aligned in a circumferential direction. The battery ECU can change a connection mode of battery module pairs, which are electrically connected to each other, between in series and in parallel. The ECU, the motor ECU, and the battery ECU are configured to initiate changing the number of the poles (S9, S10) and changing the connection mode of the battery module pairs (S13, S14) at different timings from each other (S11) .