Electric Motor Control System Reducing Thermal Losses
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Solution Overview
Problem
Three-phase electric motor systems face thermal management challenges due to high switching and conduction losses in power electronic switches, limiting power handling capacity and requiring larger motor diameters, which increases peripheral speed and reduces coil turns, leading to heat dissipation issues. Additionally, independent sub-motors with separate communication interfaces increase vehicle weight and cost.
Innovation Solution
A control system for electric motors with multiple sub-motors that uses a single communication interface for independent control, allowing each sub-motor to receive control data even if a communication fault occurs, and employs a dual-control-device configuration with CAN and SPI interfaces for redundant communication, enabling efficient torque distribution and reduced heat dissipation through increased inductance and smaller switching devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power rating of a conventional three phase motor is increased by producing a motor with a larger diameter, then the power handling capacity is improved, but the peripheral speed of the rotor increases and the coil turns must be reduced, leading to heat dissipation problems
Solution Approach 1:
The motor is divided into multiple independent sub-motors, each with its own coil sets that can be controlled independently. This segmentation allows each sub-motor to operate at optimal current levels, reducing overall heat generation while maintaining high power output capability.
Solution Approach 2:
The control system dynamically allocates torque demands across multiple sub-motors based on real-time conditions. By dynamically adjusting the operation of individual sub-motors, the system optimizes thermal management while maintaining high power handling capacity.
2Ease of operation
If each sub-motor has its own communication interface for communicating directly with a remotely mounted vehicle controller, then independent control of each sub-motor is improved, but the number of communication lines increases, resulting in increased weight and cost
Solution Approach 1:
Multiple communication interfaces are merged into a single communication interface that serves all sub-motors. The control unit receives torque demands through one interface and internally distributes them to appropriate sub-motors, eliminating the need for separate communication lines for each sub-motor.
Solution Approach 2:
The single communication interface is designed to handle multiple functions: receiving torque demands, transmitting status information, and coordinating control of multiple sub-motors. This multi-functional interface replaces what would otherwise require multiple dedicated communication channels.
3Device complexity
If a single communication interface is used for controlling multiple sub-motors, then the number of communication lines is reduced, but the reliability of control data transmission may be compromised if a fault occurs
Solution Approach 1:
The control unit is designed with built-in fault detection and redundancy capabilities that prepare for potential communication failures before they occur. If a fault is detected in the single communication interface, the system can switch to alternative control modes or use previously stored command data to maintain operation.
Solution Approach 2:
The control unit acts as an intermediary between the vehicle controller and multiple sub-motors. It receives control data through a single interface, processes the information, and distributes appropriate commands to each sub-motor. This intermediary role allows for error checking, data validation, and fallback mechanisms that enhance reliability.
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 manages thermal losses by allowing independent control of sub-motors with reduced communication lines, enhancing power handling capacity while minimizing weight and cost, and maintaining operational reliability through redundant communication pathways.
Implementation Method 1
each coil set being arranged to generate a magnetic field associated with one of the three phases of an alternating voltage
Implementation Method 2
power electronic switches will typically exhibit switching losses and conduction losses
Data Source
Figure 1
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AI summary
A control system for an electric motor, the control system comprising a first control device arranged to control current in a first coil set of the electric motor and a second control device arranged to control current in a second coil set of the electric motor; wherein the first control device includes a first interface arrangement for receiving data from a first controller for allowing the first control device to determine a required current flow in the first coil set, wherein the first interface arrangement is arranged to communicate data to the second control device for allowing the second control device to determine a required current flow in the second coil set.