Motor Drive Current Boost for Maximum Torque at Zero Speed
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Solution Overview
Problem
The redundancy design for switching transistors in electric vehicle motors, aimed at enhancing through-current capability for hill-start scenarios, results in increased costs without full utilization across various application scenarios, leading to a waste of resources.
Innovation Solution
A motor driving method that controls the motor to output a first current greater than the rated peak current but less than or equal to the maximum load current, utilizing the through-current capability of switching transistors only when thermal safety is ensured, thereby improving torque output and abrupt acceleration performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If redundancy design is used to improve through-current capability of switching transistors, then the motor can provide large output torque at zero rotational speed, but the cost of switching transistors increases and the improved capability is not fully utilized in most application scenarios
Solution Approach 1:
The patent applies dynamics by enabling the switching transistor to operate in two distinct modes: normal alternating current mode for most operating conditions, and direct current mode only when maximum torque at zero speed is required. This dynamic switching between operational modes allows the system to achieve high torque capability when needed while avoiding the continuous cost penalty of redundancy design, as the enhanced capability is only activated during specific hill-start scenarios
Solution Approach 2:
The patent changes the operational parameters of the switching transistor by controlling it to output direct current with amplitude equal to the alternating current amplitude only during hill-start conditions. This parameter change allows the transistor to utilize its full current-carrying capability temporarily, effectively using the redundancy design only when the application scenario demands maximum torque output at zero rotational speed
2Force
If switching transistors continuously output direct current to provide large output torque at zero rotational speed, then hill-start capability is improved, but the current load on switching transistors increases significantly which may shorten their life or cause damage
Solution Approach 1:
The patent applies periodic action by controlling the switching transistor to operate in direct current mode only during specific hill-start periods, rather than continuously. The control unit monitors operating conditions and activates the enhanced current output mode only when zero rotational speed with high torque demand is detected, then switches back to normal alternating current mode when the condition is no longer met. This periodic activation reduces cumulative thermal stress and extends transistor life while maintaining hill-start capability when needed
Solution Approach 2:
The patent implements beforehand cushioning by using the redundancy design of the switching transistor to provide additional current-carrying capability only when required for hill-start scenarios. The transistor is designed with built-in redundancy that acts as a cushion or buffer during extreme conditions, allowing it to handle the increased current load temporarily without damage. After the hill-start condition is resolved, the system returns to normal operation, allowing the transistor to cool down and recover, thus preventing cumulative damage
Data Source
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AI summary
Embodiments of this application disclose 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 drive to output a first current to drive the motor to rotate. The first current is greater than a rated peak current of the drive and is less than or equal to a maximum load current of the drive. 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 drive cannot be fully utilized for most customers and application scenarios.