We know BLDC motor has two connections, delta connection and star contection. What's the difference between them?

First of all, one of the differences between the star connection and the delta connection is that the connection is different. Star connection refers to the three winding ends of the three-phase power supply are connected together to become A common point, from the first end A B C leads to three lines, the first phase of the power supply end, we also called Y connection; The delta connection method refers to connecting the end and end of the three-phase winding, and the three end points are the power supply end. We need to know that whether it is the star connection and the triangle connection, there must be a three-phase AC power supply with a three-phase phase difference of 120 degrees, and 220V power supply can not be used. Why is that? Because the three-phase fireline voltage of three-phase AC power is 220V, but the phase difference between them is 120 degrees, and the voltage difference between the three phases is 380V, which can not be replaced by three firelines in the same phase.

                        Star  connetion                                                              Delta connection

Second, the difference between the star connection and the Delta connection is that the load is different. In the star connection, the line voltage is 3 times the square root of the phase voltage, and the line current is equal to the phase current. When the three-phase load is balanced, there is no current flowing through the neutral line even if it is connected. When the three-phase load is unbalanced, the neutral line should be connected, otherwise the partial pressure of each phase load will be unequal. Because there is no neutral point in the triangular connection, the head and tail of the three-phase winding of the motor are connected respectively, and there is only one voltage level, that is, the phase voltage is equal to the line voltage; The line current is equal to the phase current three times the square root.

Another difference between the star connection and the delta connection is that the voltage is not the same. Delta connection, each winding of the three-phase motor to withstand the line voltage 380V, and star connection, the motor each phase voltage 220V. In addition, the current of the star connection is different from that of the delta connection. When the motor is connected to the Y-type operation, the starting torque is only half of the delta connection, but the current is only about one-third of the delta starting. Delta starting current is 4-7 times the rated current, but the torque is large.

The star connection helps to reduce the voltage of the winding, reduce the insulation level, and reduce the starting current, but the disadvantage is that the power of the motor is reduced. The delta connection helps to improve the motor power, the disadvantage is that the starting current is large, the winding is under large voltage, and the insulation level is increased.