Motor Control via Real-Time Temperature Monitoring and PWM
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Solution Overview
Problem
Electric motors face challenges with overheating due to peak current draws, which can damage the motor and electronic equipment, and existing solutions do not effectively manage power to prevent overheating while maintaining maximum output.
Innovation Solution
A method that continuously monitors the motor's temperature and power stage in real-time, adjusting power intervals and pulse shapes to maintain operation within the maximum rated temperature, including determining optimal time intervals for power delivery and reducing current draw to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor is rated for maximum peak current to handle highest expected loads, then the motor can deliver maximum output power, but the cables, wires, and electronic equipment must be oversized for the maximum peak current, increasing device complexity and cost
Solution Approach 1:
The patent applies periodic action by implementing pulse-width modulation (PWM) to deliver power to the motor in controlled pulses rather than continuous power. The controller switches power delivery on and off at high frequency, with the duty cycle adjusted to deliver the required average power. This allows the motor to receive maximum power when needed while the cables and electronics only need to handle the switched current, not continuous peak current, thereby reducing their required size and complexity.
2Productivity
If the motor operates at maximum peak current to maintain maximum output, then productivity is maximized, but heat generation increases causing the motor to overheat and potentially stall
Solution Approach 1:
The controller uses periodic pulse delivery with adjustable duty cycles to control the average power and heat generation. By varying the proportion of time power is applied versus time power is removed, the system can maintain productivity while controlling temperature. The periodic nature allows the motor to cool between pulses when needed.
Solution Approach 2:
The patent implements feedback by continuously monitoring motor temperature and using this information to adjust the power delivery duty cycle. When temperature approaches unsafe levels, the controller reduces the duty cycle to allow cooling, and when temperature is acceptable, it increases the duty cycle to maintain productivity. This closed-loop control resolves the contradiction by dynamically balancing output and temperature.
3Productivity
If the motor delivers maximum power continuously, then productivity is maximized, but the motor will overheat and require shutdown, reducing duration of action
Solution Approach 1:
The system uses periodic power delivery with variable duty cycles to extend continuous operation time. Rather than continuous maximum power that would cause overheating and shutdown, the motor receives power in periodic pulses with sufficient cooling intervals, allowing indefinite continuous operation at high productivity levels without thermal shutdown.
Solution Approach 2:
The controller dynamically adjusts the power delivery parameters including duty cycle, pulse width, and frequency based on real-time motor temperature and load conditions. This dynamic adaptation allows the system to maintain maximum productivity when cooling is sufficient while automatically reducing power to extend operational duration when thermal limits are approached, eliminating the need for shutdowns.
4Adaptability or versatility
If the motor is allowed to draw peak current during unexpected high load, then the motor can handle the load, but detrimental peak current can damage electronic equipment and the motor itself
Solution Approach 1:
The controller implements preliminary anti-action by proactively limiting peak current through PWM control before detrimental effects can occur. Rather than allowing unrestricted peak current that could damage equipment, the controller pre-establishes current limits and uses switched power delivery to prevent harmful current spikes while still enabling the motor to handle unexpected loads within safe parameters.
Solution Approach 2:
The system uses feedback from current sensors and temperature monitors to detect approaching dangerous conditions and immediately adjusts power delivery to prevent damage. When load conditions indicate potential for harmful peak current, the controller reduces duty cycle or terminates pulses, maintaining load handling capability while protecting equipment reliability through real-time monitoring and corrective action.
Data Source
AI summary
Embodiments of the invention provide methods of controlling a motor, such as a servo motor. One method can include monitoring a current temperature of the motor and a power stage of the motor substantially continuously and substantially in real-time. This method can include determining optimum settings for a first time interval to remove power and the second time interval to provide power in order to deliver maximum output while remaining below the maximum rated temperature of the motor. One method can include pulsing power to the motor for a second time interval after a first time interval has elapsed and tailoring pulse shapes of the power provided to the motor for the second time interval. One method can include calculating a maximum phase current based on the rotor shaft torque for each real-time speed of the motor that correlates to the maximum allowable current draw from the power supply.