◆ TECHNICAL GUIDE · BLDC MOTOR TYPES

Difference between 2-phase
and 3-phase

We've written a Brushless DC Pump Definitive Guide to cover this topic. Please visit it and get a comprehensive view of brushless DC pumps.

Both 2-phase and 3-phase brushless DC pumps use low voltage DC power sources instead of 110V or 220V AC power. 3-phase brushless DC pump allows a significant increase in the pump's rated power to improve the performance. And it can work in a higher temperature environment.

Three-phase brushless DC technology is an excellent upgrade of two-phase brushless DC technology.

2-phase brushless DC motor

Side-by-side comparison of motor stators: three-phase stator (left, 6 slots) and two-phase stator (right, 4 slots) on a light blue background
Left: three-phase stator  |  Right: two-phase stator

The two-phase motor has a 4-slots stator and two pairs of magnetic fields. It must put a hall sensor inside of the pump body to check the rotor position. So we need to put the circuit inside of the pump.

When the pump was working, the motor's current will cause a high temperature (sometimes even more than 100 Celsius). In general, the electronic component's temperature resistance is 85 Celsius.

So we usually produce a two-phase pump's current of 2 amperes or less and need to guarantee the environmental temperature is less than 60~70 Celsius. Otherwise, the pump's reliability cannot be ensured.

3-phase brushless DC motor

The three-phase brushless DC motor has a 6-slots stator and three pairs of magnetic fields. The pump use MCU control, and intelligent commutation position detection without additional sensors.

So we do not need to put any electronic component inside of the pump body. We put all the circuits outside of the pump body, using the Aluminum case potting with epoxy.

Therefore, the high temperatures generated by the motor work will not influence the circuit. Meanwhile, we replaced all the pump's materials with high-temperature-resistant materials; then the pump can be used in hot water even more than 100 Celsius.

Video preview: 3 Phase DC motor control — circuit diagram and motor illustration showing sensorless commutation
3 Phase DC Motor Control -- Circuit & Operation Explained

Advantages of 3-phase brushless DC pump

A three-phase brushless DC pump has many advantages over a two-phase brushless DC pump.

When we use a three-phase brushless DC motor driven instead of a two-phase, we can make the pump power much higher, which means a much larger flow rate and higher head.

Due to the use of MCU, we can add many program functions to the pump, such as Reverse protection, stuck protection, over-current protection, manual speed control, gifted program, and so on.

Notes

Some things need to attend, three-phase DC is entirely different from three-phase AC. Three-phase DC has the same power supply as the two-phase DC, and it has two power cables, one positive and one negative. However, the three-phase AC has three power cables.

How to distinguish our two-phase and three-phase pumps?

And view our Model Code Instruction here.

Side-by-side comparison of 2-phase vs 3-phase brushless DC pump internal layout: 2-phase has Hall sensor PCB inside the pump body with 4-slot stator; 3-phase uses sensorless driver PCB outside the pump body with 6-slot stator
◆ Internal vs External Circuit Layout

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