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Switching from Mode 2 to 3 shifts the flux direction another 60º, again pulling the rotor. 3) moves the resultant flux direction by 60º, pulling the rotor along accordingly. For example, switching from Mode 1 to 2 (see Fig. With 120-degree conducting control, there are only six resultant flux directions for driving the motor. We use the name “120-degree conducting control” to the 6-mode control method described here.įigure 3: The changing resultant flux continually pulls the rotor magnet, causing the rotor to turn. The speed of rotation can be controlled by controlling the rate at which the phases change. As you can see, switching sequentially through modes 1 through 6 will cause the rotor to turn clockwise through one rotation. In other words, energizing of U, V, and W must be continually switched so that the resultant flux keeps moving, producing a rotating field that continually pulls on the rotor magnet.įigure 3 shows the relationship between energized phases and flux. Rotation is maintained by continually switching the flux so that the permanent magnet is constantly chasing the rotating magnetic field induced by the coils. The wide arrow shows the resultant flux-the sum of the flux produced by U and W. The two arrows show flux generated by coils U and W, respectively.įigure 2(d): BLDC Motor Principle of Rotation. The arrow shows flux generated by coil U.įigure 2(c): BLDC Motor Principle of Rotation.Ĭurrent flows through U and W. This large flux will cause the inner rotor to turn until the S and N poles of the rotor permanent magnet are aligned on this arrow (with the N pole closest to the arrow tip).įigure 2(b): BLDC Motor Principle of Rotation.Ĭurrent flows through U and then W.

The wide arrow in Figure 2(d) is the resultant flux-the result of the combined magnetic fields from U and W. Figure 2(c) shows what happens when current moves through coils U and W (phase “UW”), with the arrows again showing the flux generated at each coil. In actuality, all three coils are interconnected, through a single lead wire from each-and it is not possible to generate phase U in isolation. If current moves through U only, magnetic flux is generated as shown by the arrow in Fig. Since there are three coils, there are three paths through which we can pass current we can call these phase U (current into coil U), phase V (into coil V), and phase W. Remember that the passing of a current through a coil generates a magnetic field. Product Change Notifications (PCN) Searchįor our example, we show a 3-coil motor.Renesas Ready Partner Network (Software).Multi-Channel Power Management ICs (PMICs).Jitter Attenuators with Frequency Translation.R-Car Automotive System-On-Chips (SoCs).RX 32-bit Performance / Efficiency MCUs.