Vehicle Drive Motor Control System for Uphill Thermal Management
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Solution Overview
Problem
Conventional vehicle drive motor control systems fail to effectively manage overheating in coils when a vehicle is held stationary on an uphill road, leading to prolonged torque limitations that deteriorate drivability and increase the risk of thermal damage.
Innovation Solution
A vehicle drive motor control system that includes voltage conversion means, accelerator actuation detection, control means for calculating drive torque, and motor locking determination, which gradually decreases the maximum drive torque when the motor is in a locked state to encourage the driver to switch from accelerator to brake actuation, thereby redistributing current to cooler coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If current is continuously applied to one phase of the coils to hold the vehicle stopped on an uphill road, then the vehicle can be held stationary without using a brake, but the coil temperature increases causing thermal damage or failure
Solution Approach 1:
The control device switches the phase of current application periodically among the three phases (U, V, W). Instead of continuously applying current to one phase, the system cycles through different phases at predetermined intervals, ensuring that no single coil overheats while maintaining the vehicle's stationary position on the uphill road.
2Reliability
If the current applied to the coil is suddenly limited when temperature exceeds set value, then overheating or failure of the coil is avoided, but the accelerator is disabled resulting in deterioration in drivability
Solution Approach 1:
Rather than suddenly limiting current when temperature exceeds the threshold, the system implements periodic switching of current phases. This gradual, cyclic approach prevents thermal damage to coils while maintaining continuous accelerator functionality and acceptable drivability, as the torque limitation is applied smoothly rather than abruptly.
3Temperature
If drive torque is limited according to the degree of overheating, then coil temperature control is achieved, but the drive torque cannot return to original value quickly resulting in prolonged torque limitation
Solution Approach 1:
The periodic phase switching mechanism allows the system to maintain temperature control while enabling faster recovery of drive torque. By cycling through phases rather than maintaining continuous limitation, the system can more quickly return to normal operating conditions once the thermal issue is resolved, reducing the duration of torque limitation.
4Temperature
If torque decrease limitation is applied with predetermined decrease and increase ratios, then average torque can be maintained at a threshold level, but the complexity of control parameters increases
Solution Approach 1:
The periodic phase switching approach simplifies control by using time-based cycling rather than complex torque ratio calculations. The control device only needs to implement predetermined switching intervals between phases, eliminating the need for multiple predetermined decrease and increase ratio parameters while achieving similar temperature management effects.
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 prevents thermal damage to coils by gradually reducing drive torque, allowing the vehicle to move backward and switch current application to cooler coils, improving drivability and reducing overheating risks while ensuring the vehicle can return to normal operation quickly.
Implementation Method 1
an inverter 7, which converts a direct-current voltage from the high-voltage battery 8 to an alternating-current voltage and supplies the alternating-current voltage to the motor 2
Implementation Method 2
the motor 2 generates drive torque, using the alternating-current voltage
Data Source
AI summary
A vehicle drive motor control system is provided, which, when a vehicle drive motor is in a locked state, may urge a driver to make a switch from actuation of an accelerator to actuation of a brake, thereby preventing thermal damage to coils inside the motor. The vehicle drive motor control system is capable of, when a vehicle drive motor is in a locked state as a result of actuating an accelerator, making the vehicle slowly move backward (or providing other stimulus to the driver) by decreasing a maximum drive torque value. This may effectively cause the driver to make the switch from actuation of the accelerator to actuation of the brake.