# Design of brushless DC motors

We have developed a software for design of brushless DC motors with fractional number of slots per pole and phase, and with a stator winding consisting of a set of concentric coils.

Calculation of brushless DC motors is based on input data comprising: input DC voltage, nominal motor torque, nominal speed in rpm, number of phases.

The developed software enables:

Calculation steps incorporated into our design tools

1. automatic determination of optimal geometry of the motor, namely: outer stator diameter, inner stator diameter, air gap value, the active length of the motor, the geometry of stator slots, stator yoke thickness, a geometry of permanent magnets, rotor yoke thickness, shaft diameter;
2. automatic selection of permanent magnets and magnetization type of permanent magnets;
3. automatic selection of a number of turns of the stator winding, geometry of the wire and a filling factor for the stator slot;
4. automatic analysis of the magnetic circuit of the motor;
5. automatic calculation of a torque factor and a back EMF factor of the motor;
6. automatic calculation of losses and efficiency of the motor;
7. automatic calculation of dependences of motor torque, stator current and motor efficiency on the motor speed;
8. automatic calculation of dependences of motor speed, stator current and motor efficiency on the motor torque;
9. automatic thermal calculation of the motor based on a detailed equivalent thermal scheme of the motor and a graph theory

Performance characteristics

Below you will find typical performance characteristics for one of our designs:

This data corresponds to experiments.

Capabilities of our design software

Our design software enables designing of brushless DC motors either with concentric windings, or with a partial number of slots per phase per pole or with distributed windings.

We are capable of designing a single brushless DC motor as well as a series of brushless DC motors.

We can perform a full finite element analysis of a brushless DC motor.

We can perform calculation of operation modes of a brushless DC motor for different types of control including vector control.

We can perform a full thermomechanical analysis of components of a motor, such as a shaft, a housing, bearing shields and a stator winding including forces acting on the winding during operation.

We can develop a full structure of a brushless DC motor with an outline drawing or a general drawing. We can provide drawings of main components of a brushless DC motor corresponding to specific requirements of a customer.

We can design brushless DC motors for any of the following implementations: IP54, IP55 or IP23.

Based on our patent US 8253295 “Schemes of interchangeable windings of electrical machines” we can design a brushless DC motor with a sinusoidal distribution of MMF in the air-gap and a double-layer or a triple-layer stator winding not having intersections in the end-winding region. Such windings are easier for manufacturing and more suitable for pulling into the slots. This leads to better reliability of the windings and a higher filling factor for the stator slots. Brushless DC motors with a sinusoidal distribution of MMF in the air-gap have lower core losses and, consequently, a higher efficiency and produce less noise.