Motor Driver Circuit Regenerative Heat Management
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Solution Overview
Problem
Existing motor driver circuits for vacuum pumps face challenges in managing heat generated by regenerative resistance, requiring either high-capacity regenerative resistances or cooling systems like heat sinks and large FANs, which increase cost and size, while reducing current to restrain heat prolongs brake time.
Innovation Solution
The motor driver circuit adjusts the driving current based on motor speed to optimize energy consumption by the regenerative resistance, allowing for a short brake time within a safe temperature range without additional cooling components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high-capacity regenerative resistance is used to achieve short brake time, then brake time is reduced, but cost and device size increase
Solution Approach 1:
The patent applies dynamics by making the regenerative resistance value variable rather than fixed. The resistance value is dynamically adjusted based on motor speed: at high speeds, lower resistance values are used to maximize energy recovery and reduce brake time, while at low speeds, higher resistance values are used to limit heat generation. This dynamic adaptation allows the system to achieve short brake times without requiring excessively high-capacity resistance components throughout the entire operating range.
Solution Approach 2:
The patent changes the parameter of regenerative resistance value based on operating conditions (motor speed). By switching between different resistance values according to speed thresholds, the system optimizes both brake performance and thermal management. This parameter change approach allows using smaller, lower-cost resistance components while maintaining effective braking across different operating conditions.
2Temperature
If current to regenerative resistance is reduced to restrain heat, then temperature is controlled, but brake time is prolonged
Solution Approach 1:
The system dynamically adjusts resistance values based on real-time motor speed feedback. During high-speed braking, lower resistance values allow higher current flow and faster energy dissipation, achieving short brake times. During low-speed braking, higher resistance values automatically limit current and reduce heat generation, controlling temperature. This dynamic adjustment eliminates the need to choose between heat control and brake time performance.
Solution Approach 2:
The patent implements periodic switching between different resistance values based on speed thresholds. As the motor decelerates through different speed ranges, the system periodically changes the resistance configuration, optimizing performance for each speed band. This periodic action ensures that heat is restrained only when necessary (at low speeds) while maintaining fast braking capability at high speeds.
3Temperature
If cooling systems like heat sinks and large FANs are added to manage heat, then temperature is controlled, but device volume and cost increase
Solution Approach 1:
The patent extracts the heat management function from passive thermal management components (heat sinks, large FANs) and implements it through active electrical control of the regenerative resistance. By using variable resistance values to control power dissipation, the system eliminates or reduces the need for bulky passive cooling components, achieving temperature control without increasing device volume.
Solution Approach 2:
The patent replaces the mechanical cooling system (FANs and heat sinks) with an electrical control system that manages heat through variable resistance switching. Instead of using mechanical means to remove heat, the system uses electrical parameter changes to control heat generation at its source, substituting a simpler electrical control mechanism for complex mechanical thermal management.
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
This approach enables a compact, low-cost motor driver circuit that effectively manages heat and achieves appropriate brake times without high-capacity resistances or large cooling systems, maintaining the regenerative resistance within a specific temperature range.
Implementation Method 1
a regenerative resistance 207, and a drive transistor 206 for driving the motor 121. The motor driver circuit 200 controls an amount of energy to be consumed by the regenerative resistance 207 depending on a rotation number of the motor 121.
Implementation Method 2
heat generated by a regenerative resistance within a specific temperature range
Data Source
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AI summary
Provided are a compact and low-cost motor driver circuit capable of achieving an appropriate brake time and restraining heat generated by a regenerative resistance within a specific temperature range without employing a regenerative resistance having a greater capacity, a heat sink, or a FAN generating a larger volume of air, and a vacuum pump having the motor driver circuit. Regenerative current is controlled so that a speed characteristic gradually approaches inclination "a" from inclination "b" depending on the motor speed in the initial stage of regeneration. In addition, a limit is set not to pass further current when the regenerative current reaches a maximum brake current value Iset_brake_max. As stated above, when the motor is braked, control is performed so that the initial brake current value at the maximum rated speed is set low and the brake current is increased as the rotational speed decelerates.