What role does magnetic steel thickness play in motor performance?

The magnetic circuit is similar to the electric circuit, and the magnet and the power supply can be compared. Only the thickness is increased, and the magnetic flux corresponding to the residual magnetism remains unchanged, but the internal magnetic resistance increases. When the magnetic resistance of the external magnetic circuit remains unchanged, the magnetic flux of the external magnetic circuit will increase.

About demagnetization: As the corresponding magnetomotive force of the magnet increases, the internal magnetic resistance increases. Under the same demagnetization magnetic potential, the magnetic flux is small and the anti-demagnetization ability is strong.

Weak magnetic properties are similar to demagnetization analysis, and weak magnetic properties are difficult. On the other hand, the d-axis magnetic resistance is large, Ld is small, and weak magnetic properties are difficult.

As the back electromotive force increases, the torque coefficient increases, the copper loss decreases, but it is hard to say about the iron loss.

The cost has increased seriously.

Cogging torque: When the breath magnetic density waveform remains unchanged, the derivative of magnetic energy with respect to angle increases and the cogging torque increases.

Back EMF waveform: Generally speaking, the tooth magnetic flux saturation contains the third harmonic, the back EMF waveform becomes flat, and the torque fluctuation increases.

I found a motor model with an ipm structure and parameterized motor magnetic steel thickness, which is shown as follows:

Relationship between air gap magnetic flux density and magnetic steel thickness

The air gap flux density increases with the thickness of the magnetic steel, but not linearly.

Cogging torque

The cogging torque increases due to the increased air gap flux density.

efficiency

In this example, when the output torque is fixed and the magnetic steel increases, the rate at which the iron loss increases is greater than the rate at which the copper loss decreases.

Maximum output power

The thicker the magnet, the greater the maximum output power capability.

Stator tooth flux density

It is natural that the magnetic density of the teeth increases.

The d-axis inductance decreases as the magnet thickness increases.

Test Data

According to actual test data: as the thickness of the magnetic steel increases, the performance at both low and high speeds increases.

The solution is as follows:

Solution 1: Stator core thickness = rotor core thickness = magnetic steel thickness (stator core and rotor core thickness are the same)

Solution 2: Stator core thickness = rotor core thickness - 5mm = magnetic steel thickness - 5mm (the rotor core thickness is 5mm thicker than the stator core, and other test conditions remain unchanged. The low-speed and high-speed torques of the motor measured are increased (temperature rise and heat generation are not measured).

As a key component of the motor, the magnet affects the performance of the motor. The thickness of the magnet affects the motor's magnetic flux density, magnetic flux and magnetic resistance, thereby affecting the motor's torque, efficiency, output power and other performance parameters:

The influence of magnetic steel thickness on magnetic flux density: The thickness of magnetic steel has a direct influence on magnetic flux density. The greater the magnetic flux density, the greater the torque of the motor. Therefore, under the same power and current conditions, thicker magnetic steel will produce higher torque.

The effect of magnetic steel thickness on magnetic flux: Magnetic flux is the size of magnetic flux generated by the motor, which is affected by the area and thickness of the magnetic steel. As the thickness of the magnetic steel decreases, the magnetic flux will also decrease, so the efficiency of the motor will also decrease.

The influence of magnetic steel thickness on magnetic resistance: The thickness of magnetic steel affects magnetic resistance. The smaller the magnetic resistance, the easier it is for the magnetic flux of the motor to be transmitted through the magnetic field, the greater the torque, and the higher the efficiency. In mechanical design, minimum magnetic resistance is one of the key points of design optimization.

Therefore, for the same brand of magnetic steel, the impact of different thicknesses is real. Different magnetic steel thicknesses will cause significant changes in the performance of the motor, and the impact is extremely drastic.