Programmable Permanent Magnet Actuator for Low-Speed Torque Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electromagnetic motors are inefficient for robotic applications due to their inability to provide high torque at low rotational speeds, leading to excessive power consumption and heat generation, and existing solutions like gearboxes and electropermanent magnets fail to address the root issue of inefficiency and torque adjustability.
Innovation Solution
A Programmable Permanent Magnet (PPM) actuator that uses high transient current pulses to store magnetic fields in hard ferromagnetic material, allowing for adjustable torque control and efficient operation at low speeds, utilizing a Halbach array configuration to focus magnetic fields and minimize leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional electromagnetic motors are used to provide high torque, then torque output is improved, but power consumption increases excessively at low speeds
Solution Approach 1:
The patent applies periodic pulsed magnetic fields to magnetize hard ferromagnetic material in the stator, allowing the motor to maintain torque without continuous power input. The pulsed action creates temporary magnetic fields that align magnetic domains in the hard ferromagnetic material, enabling torque generation only when needed rather than continuous operation.
Solution Approach 2:
The patent changes the magnetic properties of the stator material from soft ferromagnetic to hard ferromagnetic material, which has different hysteresis characteristics. Hard ferromagnetic material retains magnetization longer and requires less continuous energy input to maintain magnetic fields, thereby reducing power consumption while maintaining torque output.
2Force
If conventional electromagnetic motors operate at low rotational speed, then torque is improved, but efficiency deteriorates due to excessive power loss
Solution Approach 1:
By using periodic pulsed fields instead of continuous fields, the system minimizes energy loss during low-speed operation. The pulsed action allows the motor to build up magnetic fields only when torque is required, rather than maintaining continuous fields that would dissipate energy as heat during low-speed operation.
Solution Approach 2:
Changing from soft to hard ferromagnetic material in the stator alters the hysteresis loop characteristics, reducing energy loss during magnetization cycles. Hard ferromagnetic material has higher coercivity and retains magnetization better, reducing the energy required for each magnetization cycle and thereby reducing power loss at low speeds.
3Force
If conventional motors provide high torque at low speed, then torque output is improved, but heat generation increases
Solution Approach 1:
The periodic pulsed field operation allows the motor to generate torque only when needed, with off-periods allowing heat dissipation. This intermittent operation pattern prevents continuous heat accumulation that would occur with conventional motors maintaining continuous fields during low-speed high-torque operation.
Solution Approach 2:
The use of hard ferromagnetic material changes the magnetic hysteresis characteristics, reducing the energy converted to heat during magnetization cycles. The material's higher coercivity means less energy is lost as heat during each magnetization-demagnetization cycle compared to soft ferromagnetic materials.
4Adaptability or versatility
If electropermanent magnets are used for torque control, then torque adjustability is improved, but device complexity increases
Solution Approach 1:
The patent divides the stator into multiple independent magnetizable segments or zones, each controllable by separate pulsed fields. This segmentation allows independent control of different stator regions to achieve variable torque output and directional control, providing torque adjustability similar to electropermanent magnets but using simpler pulsed field application.
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 PPM actuator provides adjustable torque without continuous power input, reducing energy consumption and heat generation, making it suitable for robotic applications requiring low-speed, high-torque movements.
Implementation Method 1
A magnetic field generation device, such as a coil winding or strong magnet, is provided and controlled to generate a magnetic field to modify a magnetization of the stator
Implementation Method 2
The produced magnetic field is variably controlled and has a shape and an intensity that are at least in part determined by the magnetization of the stator in order to move the rotor
Implementation Method 3
utilizing a Halbach array configuration to focus magnetic fields and minimize leakage
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A programmable permanent magnet actuator, a magnetic field generation apparatus and a method of controlling thereof. The actuator has a first body that is a ferromagnetic material, a second body that is a single magnetized ferromagnet and a magnetic field generation device associable to the second body to generate a magnetic field in proximity with the second body. The actuator also has a controller adapted to control the magnetic field generation device to generate a controlled magnetic field. The controlled magnetic field is adapted to modify a magnetization of the second body such as to produce with the second body a required magnetic field to move one of the first or the second body with respect to one another according to a desired position or a desired torque. The desired position or the desired torque is maintained even after the application of the controlled magnetic field. The apparatus has a permanent magnet that has an intrinsic coercivity (Hci) value that is greater than 200kA/m and a remanence (Br) value that is greater than 0.4 Tesla. The apparatus also has a magnetic field generation device associated to the permanent magnet and a controller connected to the magnetic field generation device. The controller is adapted to control the magnetic field generation device to produce a controlled magnetic field to variably modify a magnetization of the permanent magnet in order to produce a desired variable magnetic field and influence the electrically charged or magnetized material when placed in the desired variable magnetic field.