Motor Driver Overcurrent Control for Peak Torque Without Overheating
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Solution Overview
Problem
The redundancy design used to enhance the through-current capability of switching transistors in motor drivers for electric vehicles, while effective in specific scenarios like hill starts, results in increased costs that are not fully utilized in most application scenarios, leading to wastage due to low application probability.
Innovation Solution
A motor driving method that controls the driver to output a first current greater than the rated peak current but less than or equal to the maximum load current, utilizing the improved through-current capability only when necessary, and ensuring thermal safety by determining the heat capacity margin of the motor driving system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If redundancy design is used to improve through-current capability of switching transistors, then the motor can provide maximum torque in blocking status, but the cost of the switching transistor increases
Solution Approach 1:
The patent applies dynamics by enabling the switching transistor to operate in two distinct modes: normal alternating current mode for standard operation, and direct current mode for blocking status. The controller dynamically switches between these modes based on operational requirements, allowing the transistor to deliver maximum current only when needed for hill-start capability, thereby justifying the increased cost through enhanced performance in critical scenarios
2Power
If redundancy design is used to improve through-current capability, then maximum torque can be achieved in blocking status, but the application probability is low leading to cost waste
Solution Approach 1:
The patent implements partial action by providing enhanced through-current capability that exceeds normal operational requirements. The redundancy design allows the switching transistor to handle currents significantly higher than typical operation demands, but this enhanced capability is only activated partially during specific blocking status scenarios such as hill-starts, where maximum torque is critically needed
3Power
If first current greater than rated peak current is output to enhance torque output, then abrupt acceleration performance is improved, but thermal safety risk increases
Solution Approach 1:
The patent employs feedback control by continuously monitoring the heat capacity margin of the motor driving system. The controller adjusts the current output based on real-time thermal conditions, allowing the system to deliver enhanced current (first current) only when thermal headroom is sufficient. This feedback mechanism ensures that torque enhancement does not compromise thermal safety, as the controller can reduce or stop enhanced current delivery when temperature limits are approached
Data Source
AI summary
The disclosure discloses a motor driving method, an apparatus, and a system, and relate to the chip field. The solution may include: When a motor control apparatus determines that a motor needs to rotate at a maximum torque, the motor control apparatus controls a driver to output a first current to drive the motor to rotate. The first current is greater than a rated peak current of the driver and is less than or equal to a maximum load current of the driver. This method can resolve a problem that a waste of costs is caused because a through-current capability improved by a redundancy design of a switching transistor of a motor driver cannot be fully utilized for most customers and application scenarios.