About the Two-phase Motor and Three-phase Motor of the BLDC Water Pump


The BLDC water pump uses the principle of a permanent magnet brushless DC motor, and an impeller is added to its rotor. The housing structure is designed as a cavity for the centrifugal movement of the liquid. Because there is no carbon brush friction, no sparks will be generated. High efficiency and low power consumption, and with longer lifetime and lower noise than brush motors.

The three-phase motor in the BLDC water pump is soft-started with no impact, and the starting power consumption is low. The pump body is made of high temperature resistant material, thus it can be used in high temperature applications. And it has protection functions such as blocked protection, polarity protection, overload protection, and over-current protection. In this section, we will explain the difference between the three-phase motor and the two-phase motor on a BLDC water pump.

1.What is a two-phase motor and a three-phase motor?
1.1 Two-phase motor: 2 phases, 4 poles, two pairs of magnetic poles interact with the magnetic field of the energized stator assembly to generate rotational torque, which drives the rotor to rotate, and the interior is composed of 4 coils.

1.2 Three-phase motor: 3 phases and 4 poles, two pairs of magnetic poles interact with the magnetic field of the energized stator assembly to generate rotational torque, which drives the rotor to rotate, and the interior is composed of 6 coils.

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2. Advantages and Disadvantages of Two-phase Motors and Three-phase Motors

The three-phase motor has one more set of coils than the two-phase motor, and the commutation angle of the two pairs of poles is 60°, which is smaller than that of the two-phase motor, which is 90°, so:

2.1 Compared with two-phase motors, three-phase motors have the advantages of higher efficiency, larger starting torque, and smaller size. The only disadvantage is that three-phase power is required;

2.2 The commutation of the three-phase motor is stable, without stuttering and shaking. Compared with the noise of a two-phase motor with the same power, the noise of a three-phase motor is lower;

2.3 The three-phase motor does not need any starting device, it can start by itself, and the start is stable; while to start a two-phase motor, it is necessary to design an offset angle on the stator core. In comparison, the starting stability of the three-phase motor will be better;

2.4 Three-phase motors have good heat dissipation performance and require less power than two-phase motors to achieve the same flow rate, water head and performance. For example, products with the same flow rate and water head:

If using a two-phase motor, the commutation is not smooth enough, easy to get stuck, and the lifespan is shorter than that of a three-phase motor;

With a three-phase motor, the power is relatively smaller, the heat generation is lower, the performance of the water pump is more stable, and the service life is relatively longer.

The water pump using a three-phase motor can achieve a higher water head with lower heat generation and stable overall performance. For example, TOPSFLO TL-C06 miniature BLDC water pump has 10-20W lower power than the two-phase motor water pump with the same parameters, and has lower heat generation and longer lifetime.

3. What products are two-phase motors and three-phase motors suitable for?

Generally, two-phase motors will be used for pumps with small power and small flow rate & water head, such as TOPSFLO TL-A02, TL-B03, TL-B10, TL-TS5, etc., which are mainly used in all-in-one purifiers, hot drink machines, and water boilers , coffee machines, solar water heaters and other applications.

It is recommended to use three-phase dc motors for pumps with large power and high flow rate, especially with high water head, such as TOPSFLO TL-C01, TL-C02, TL-C04, TL-TA60, TL-TD5, etc., which are mainly used for water heating mattresses, smart toilets, automotive circulation systems, medical beauty equipment, water heaters and other applications.

Here above is the knowledge about the three-phase motor and two-phase motor of a BLDC water pump. Hope it’s of significant value to you. If you have any questions about the water pumps, don't hesitate to leave us a message. Look forward to communicating with you!