Patent ID: 12255563

DETAILED DESCRIPTION

Preferred embodiments according to the present invention will be described in detail with reference to the drawings.

FIG.1is a schematic diagram showing a motor controller10according to one embodiment of the present invention. The motor controller10is used for driving a motor M, where the motor M may be a three-phase motor. The motor M has a first coil L1, a second coil L2, and a third coil L3. The motor controller10comprises a switch circuit100, a control unit110, and a detecting unit120. The switch circuit100includes a first transistor101, a second transistor102, a third transistor103, a fourth transistor104, a fifth transistor105, a sixth transistor106, a first terminal W, a second terminal U, and a third terminal V, where the switch circuit100is coupled to the motor M for driving the motor M. The first terminal W, the second terminal U, and the third terminal V respectively provides a first driving signal WO, a second driving signal UO, and the third driving signal VO for driving the motor M. The first transistor101is coupled to a fourth terminal VCC and the first terminal W while the second transistor102is coupled to the first terminal W and a fifth terminal GND. The third transistor103is coupled to the fourth terminal VCC and the second terminal U while the fourth transistor104is coupled to the second terminal U and the fifth terminal GND. The fifth transistor105is coupled to the fourth terminal VCC and the third terminal V while the sixth transistor106is coupled to the third terminal V and the fifth terminal GND. The system may provide a power voltage to the motor controller10via the fourth terminal VCC, so as to enable the motor controller10to operate normally. Each of the first transistor101, the third transistor103, and the fifth transistor105may be a p-type MOSFET. Each of the second transistor102, the fourth transistor104, and the sixth transistor106may be an n-type MOSFET.

One terminal of the first coil L1is coupled to the first terminal W. One terminal of the second coil L2is coupled to the second terminal U. One terminal of the third coil L3is coupled to the third terminal V. Furthermore, another terminal of the first coil L1is coupled to another terminal of the second coil L2and another terminal of the third coil L3. That is to say, the first coil L1, the second coil L2, and the third coil L3form a Y-shaped configuration. The control unit110generates a first control signal C1, a second control signal C2, a third control signal C3, a fourth control signal C4, a fifth control signal C5, and a sixth control signal C6for respectively controlling the ON/OFF states of the first transistor101, the second transistor102, the third transistor103, the fourth transistor104, the fifth transistor105, and the sixth transistor106. The detecting unit120is coupled to the first terminal W, the second terminal U, and the third terminal V, so as to generate a first detecting signal Vd1and the second detecting signal Vd2to the control unit110. The detecting unit120may be used for detecting the current ILW of the first coil L1and a back electromotive force of a floating phase. The switch circuit100is configured to supply the current ILW of the first coil L1to the first coil L1. Moreover, the motor controller10further comprises a pulse width modulation signal Vp, where the pulse width modulation signal Vp has a duty cycle. The control unit110receives the pulse width modulation signal Vp for adjusting the rotation speed of the motor M.

FIG.2is a timing chart according to one embodiment of the present invention. When the motor M is in a still state, the motor controller10generates a fixed set of voltage waveforms to the first terminal W, the second terminal U, and the third terminal V respectively, so as to enable the first driving signal WO, the second driving signal UO, and the third driving signal VO to be a six-step square wave signal or sinusoidal signal for driving the motor M. At this moment the motor controller10enters an early alignment state and enables the duty cycle of the pulse width modulation signal Vp to vary rapidly, such that the current ILW of the first coil L1may achieve a predetermined value CL within one electric period rapidly. When the current ILW of the first coil L1achieves the predetermined value CL, the detecting unit120enables the first detecting signal Vd1to change from a low level to a high level, so as to inform the control unit110to record the duty cycle. Then the motor controller10enables the duty cycle to decrease in a very slow rate for stabilizing the motor M. Afterwards, the motor controller10enables the motor M to rotate in an accelerated pace. By the recorded duty cycle, the motor controller10enables the current ILW of the first coil L1to be less than or equal to a ratio of the predetermined value CL in a starting procedure, where the ratio may be greater than or equal to 1. When the rotation speed of the motor M achieves a predetermined rotation speed, the motor controller10starts a floating phase for detecting a phase switching time point, where the floating phase is formed in the first coil L1. When a zero crossing point of a back electromotive force is detected by the detecting unit120, the detecting unit120enables the second detecting signal Vd2to change from the low level to the high level, so as to inform the control unit120to carry out a phase switching procedure. Thus, the motor controller10may protect the first coil L1and increase a success rate of starting the motor M under different power voltages. Furthermore, the motor controller10may additionally set a predetermined number of turns to decide whether or not to start the floating phase for detecting the phase switching time point. When the motor M rotates the predetermined number of turns, the motor controller10is allowed to start the floating phase for detecting the phase switching time point.

In order to increase the success rate of starting the motor M, the motor controller10is designed to be capable of completing the starting procedure successfully under different output loads. That is to say, each of an electric period of an early alignment stage, the predetermined value CL, the predetermined rotation speed, and the predetermined number of turns may be a variable value. For example, when the motor M is in a light load state, the electric period of the early alignment stage may be a smaller value. When the motor M is in a heavy load state, the electric period of the early alignment stage may be a larger value, such that the motor M has enough time to stabilize. When the motor is in the light load state, the predetermined number of turns may be a smaller value. When the motor is in the heavy load state, the predetermined number of turns may be a larger value.

One embodiment of the present invention utilizes a current limit technology, so as to enable a coil current to achieve a predetermined value rapidly within one electric period and record a duty cycle simultaneously. By the current limit technology, a motor controller is able to protect a motor coil and increase a success rate of starting a motor under different power voltages. The motor controller may be applied to a single-phase or polyphase configuration.

While the present invention has been described by the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.