Ordinary permanent magnet brushless motors are capable of providing variable speed outputs. However, in some applications, a particular motor’s Speed/Torque profile may not be sufficient to cover the desired Speed/Torque range. In these circumstances two options are available; a more powerful motor could be used to cover the entire range but this would be bulkier and heavier. Alternatively, mechanical gears could be provided for the motor. Both these methods add cost, weight and size to the system.

In our patented design the electronic magnetic gearing is achieved by special configuration of the motor windings and an electronic switching printed circuit board. By, altering the way in which the windings are connected, we can alter the magnetic field, inductance and resistance of the motor. This allows us to generate high torque at low speeds and high speeds at low torque levels without the need for a larger motor or mechanical gears. Therefore, a much smaller motor can be used which generates multi-parallel Speed/Torque profile curves and hence acts like a gearbox without any moving parts.

Our design is particularly suitable for aerospace applications, wind power generation and the automotive industry. The flexibility of the stepping between the parallel Speed/Torque curves of these electronically magnetically geared motors will provide manufacturers with an opportunity to utilize an efficient versatile motor in a wide variety of projects.

Summary:

• Motor with electronic magnetic gearing, and with no moving parts except for the rotor.
• Motors which provide multi-parallel Speed/Torque profile curves. This generates high torque at low speeds and high speeds at low torque levels.
• Motors could be utilized in applications where size, weight and current limitations are important.
• The electronically magnetically geared motor draws less peak current than a standard brushless dc motor. Therefore, in electric and hybrid vehicles the life of the battery pack and mileage range is increased.
• Motors act as generators under deceleration and braking conditions.
• Motors could be used as generators in direct drive wind turbines.
• Greater speed control of wind turbines could be achieved using electronic magnetic gearing.
• Motors can be used in aerospace applications to save weight and hence associated fuel costs.

PMBLDCVariable Speed Drive
Motor under Test