Motor controller

Abstract

A motor controller comprises a switching circuit, a drive circuit, and a pulse width modulation circuit. The switching circuit is coupled to a three-phase motor to drive the motor. The drive circuit generates a plurality of control signals to control the switching circuit. When the three-phase motor is operating in a startup state, the motor controller can divide an electrical cycle into a larger number of floating phase time intervals for phase switching, thereby increasing the success rate of commutation. When the three-phase motor is operating in a stable state, the motor controller can divide the electrical cycle into a smaller number of floating phase time intervals for phase switching, thereby reducing noise and vibration of the three-phase motor.

Description

Technical Field

[0001] The present invention relates to a motor controller, and more particularly to a motor controller applicable to a sensorless three-phase motor. Background Art

[0002] Traditionally, three-phase motors can be driven in two ways. One uses Hall sensors to switch phases and drive the motor. The other is to drive the motor without Hall sensors. Because Hall sensors are susceptible to environmental influences, resulting in reduced sensing accuracy, and adding Hall sensors increases system size and cost, sensorless drive methods have been proposed to address these issues.

[0003] In sensorless drive methods, a motor controller detects the back EMF of a floating phase to switch phases and drive a three-phase motor. However, when the motor controller detects the back EMF during a floating phase, discontinuous phase current is generated during that floating phase, causing noise and vibration in the three-phase motor. Therefore, reducing noise and vibration in three-phase motors is a goal. Summary of the Invention

[0004] In view of the aforementioned problems, an object of the present invention is to provide a motor controller that can reduce the noise and vibration of a three-phase motor.

[0005] According to the present invention, a motor controller is provided. The motor controller is used to drive a three-phase motor, wherein the three-phase motor has a first coil, a second coil, and a third coil. The motor controller has a switching circuit, a driving circuit, and a pulse width modulation circuit. The switching circuit has a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a first terminal, a second terminal, and a third terminal, wherein the switching circuit is coupled to the three-phase motor to drive the three-phase motor. One terminal of the first coil is coupled to the first terminal. One terminal of the second coil is coupled to the second terminal. One terminal of the third coil is coupled to the third terminal. In addition, the other terminal of the first coil is coupled to the other terminal of the second coil and the other terminal of the third coil. In other words, the first coil, the second coil, and the third coil are arranged in a Y-shaped manner. The driving circuit generates a first control signal, a second control signal, a third control signal, a fourth control signal, a fifth control signal, and a sixth control signal for controlling the conduction of the first transistor, the second transistor, the third transistor, the fourth transistor, the fifth transistor, and the sixth transistor, respectively. The pulse width modulation circuit generates a pulse width modulation signal to the driving circuit, wherein the pulse width modulation signal has a duty cycle. The motor controller can control the rotational speed of the three-phase motor by adjusting the duty cycle.

[0006] When the three-phase motor is operating in a startup state, the motor controller can divide an electrical cycle into more floating phase time intervals to switch phases, thereby increasing the success rate of commutation. When the three-phase motor is operating in a stable state, the motor controller can divide the electrical cycle into fewer floating phase time intervals to switch phases, thereby reducing the noise and vibration of the three-phase motor. That is, the motor controller first divides the electrical cycle into N1 floating phase time intervals to switch phases. After the three-phase motor operates for a first time, the motor controller divides the electrical cycle into N2 floating phase time intervals to switch phases, where N1 and N2 are both positive integers and N1>N2. When the electrical cycle is divided into N1 floating phase time intervals, the three-phase motor operates in a startup mode. When the electrical cycle is divided into N2 floating phase time intervals, the three-phase motor operates in a steady-state mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 FIG. 1 is a schematic diagram of a motor controller according to an embodiment of the present invention.

[0008] Figure 2 This is a first timing diagram according to an embodiment of the present invention.

[0009] Figure 3 FIG. 2 is a second timing diagram according to an embodiment of the present invention.

[0010] Figure 4 FIG. 4 is a third timing diagram according to an embodiment of the present invention.

[0011] Figure 5 FIG. 4 is a fourth timing diagram according to an embodiment of the present invention.

[0012] Explanation of reference numerals: 10 - motor controller; VCC - terminal; GND - terminal; 100 - switch circuit; 110 - drive circuit; 120 - pulse width modulation circuit; Vp - pulse width modulation signal; 101 - first transistor; 102 - second transistor; 103 - third transistor; 104 - fourth transistor; 105 - fifth transistor; 106 - sixth transistor; U - first terminal; V - second terminal; W - third terminal; C1 - first control signal; C2 - second control signal; C3 - third control signal signal; C4-fourth control signal; C5-fifth control signal; C6-sixth control signal; L1-first coil; L2-second coil; L3-third coil; M-three-phase motor; UO-first voltage signal; VO-second voltage signal; WO-third voltage signal; T-electrical cycle; T1-first floating phase time interval; T2-second floating phase time interval; T3-third floating phase time interval; T4-fourth floating phase time interval; T5-fifth floating phase time interval; T6-sixth floating phase time interval. DETAILED DESCRIPTION

[0013] The following description will make the purpose, features, and advantages of the present invention more apparent.Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of a motor controller 10 according to an embodiment of the present invention. The motor controller 10 is used to drive a three-phase motor M, wherein the three-phase motor M has a first coil L1, a second coil L2, and a third coil L3. The motor controller 10 includes a switching circuit 100, a driving circuit 110, and a pulse width modulation circuit 120. The switching circuit 100 includes a first transistor 101, a second transistor 102, a third transistor 103, a fourth transistor 104, a fifth transistor 105, a sixth transistor 106, a first terminal U, a second terminal V, and a third terminal W. The switching circuit 100 is coupled to the three-phase motor M to drive the three-phase motor M. The first terminal U has a first voltage signal UO. The second terminal V has a second voltage signal VO. The third terminal W has a third voltage signal WO. The first transistor 101 is coupled to a terminal VCC and the first terminal U, while the second transistor 102 is coupled to the first terminal U and a terminal GND. The third transistor 103 is coupled to the terminal VCC and the second terminal V, while the fourth transistor 104 is coupled to the second terminal V and the terminal GND. The fifth transistor 105 is coupled to the terminal VCC and the third terminal W, while the sixth transistor 106 is coupled to the third terminal W and the terminal GND. The first transistor 101, the third transistor 103, and the third transistor 103 can each be a P-type metal oxide semiconductor transistor. The second transistor 102, the fourth transistor 104, and the sixth transistor 106 can each be an N-type metal oxide semiconductor transistor.

[0015] One end of the first coil L1 is coupled to the first terminal U. One end of the second coil L2 is coupled to the second terminal V. One end of the third coil L3 is coupled to the third terminal W. Furthermore, the other end of the first coil L1 is coupled to the other end of the second coil L2 and the other end of the third coil L3. In other words, the first coil L1, the second coil L2, and the third coil L3 are arranged in a Y-shape. The driving circuit 110 generates 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 C6 to control the conduction states of the first transistor 101, the second transistor 102, the third transistor 103, the fourth transistor 104, the fifth transistor 105, and the sixth transistor 106, respectively. The pulse width modulation circuit 120 generates a pulse width modulation signal Vp to the driving circuit 110, where the pulse width modulation signal Vp has a duty cycle. The motor controller 10 can control the speed of the three-phase motor M by adjusting the duty cycle.

[0016] Figure 2This is a first timing diagram of an embodiment of the present invention. The motor controller 10 divides the electrical cycle T into 6 floating phase time intervals to detect the back electromotive force and then switch the phase. When the three-phase motor M is operating in a startup state, since the operation of the three-phase motor M is not yet stable at this time, the 6 floating phase time intervals can be used to detect the back electromotive force. For example, the motor controller 10 can sequentially detect the switching point in the first floating phase time interval T1, the second floating phase time interval T2, the third floating phase time interval T3, the fourth floating phase time interval T4, the fifth floating phase time interval T5 and the sixth floating phase time interval T6 to drive the three-phase motor M. The motor controller 10 sequentially turns on the third coil L3 and the second coil L2 in the first floating phase time interval T1, so that a floating phase is formed in the first coil L1. At this time, the motor controller 10 can detect the switching point by detecting the first voltage signal UO. During the second floating phase time interval T2, the motor controller 10 sequentially turns on the first coil L1 and the second coil L2, forming a floating phase in the third coil L3. At this time, the motor controller 10 can detect the commutation point by detecting the third voltage signal WO. During the third floating phase time interval T3, the motor controller 10 sequentially turns on the first coil L1 and the third coil L3, forming a floating phase in the second coil L2. At this time, the motor controller 10 can detect the commutation point by detecting the second voltage signal VO. During the fourth floating phase time interval T4, the motor controller 10 sequentially turns on the second coil L2 and the third coil L3, forming a floating phase in the first coil L1. At this time, the motor controller 10 can detect the commutation point by detecting the first voltage signal UO. During the fifth floating phase time interval T5, the motor controller 10 sequentially turns on the second coil L2 and the first coil L1, forming a floating phase in the third coil L3. At this time, the motor controller 10 can detect the commutation point by detecting the third voltage signal WO. During the sixth floating-phase time interval T6, the motor controller 10 sequentially conducts current through the third coil L3 and the first coil L1, forming a floating phase in the second coil L2. At this point, the motor controller 10 detects the commutation point by monitoring the second voltage signal VO. Furthermore, at the boundary of a floating-phase time interval, the motor controller 10 gradually changes the duty cycle of the pulse-width modulation signal Vp to modulate a phase current. This allows for smooth phase current changes, reducing noise and vibration in the three-phase motor M. Figure 3 FIG2 is a second timing diagram of an embodiment of the present invention. The motor controller 10 divides the electrical cycle T into three floating phase time intervals to detect back electromotive force and switch phases. Figure 4 FIG3 is a third timing diagram of an embodiment of the present invention. The motor controller 10 divides the electrical cycle T into two floating phase time intervals to detect back electromotive force and then switch phases. Figure 5 This is a fourth timing diagram of an embodiment of the present invention. The motor controller 10 divides the electrical cycle T into a floating phase time interval to detect back electromotive force and then switch phases.

[0017] Specifically, when the three-phase motor M operates in a starting state, the motor controller 10 can divide the electrical cycle T into more floating phase time intervals to switch phases, thereby increasing the success rate of commutation. When the three-phase motor M operates in a stable state, the motor controller 10 can divide the electrical cycle T into fewer floating phase time intervals to switch phases, thereby reducing the noise and vibration of the three-phase motor M. That is, the motor controller 10 first divides an electrical cycle into N1 floating phase time intervals to switch phases. After the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into N2 floating phase time intervals to switch phases, where N1 and N2 are both positive integers and N1>N2. When the electrical cycle is divided into N1 floating phase time intervals, the three-phase motor M operates in a starting state. When the electrical cycle is divided into N2 floating phase time intervals, the three-phase motor M operates in a stable state. According to the above rules, there can be at least 7 or more embodiments as follows:

[0018] 1. The motor controller 10 first divides the electrical cycle into six floating phase time intervals for phase switching. After the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into one floating phase time interval for phase switching.

[0019] 2. The motor controller 10 first divides the electrical cycle into 6 floating phase time intervals for phase switching. After the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into 2 floating phase time intervals for phase switching.

[0020] 3. The motor controller 10 first divides the electrical cycle into six floating-phase time intervals for phase switching. When the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into two floating-phase time intervals for phase switching. When the three-phase motor M operates for a second time, the motor controller 10 divides the electrical cycle into one floating-phase time interval for phase switching, where the second time interval is greater than the first time interval.

[0021] 4. The motor controller 10 first divides the electrical cycle into 6 floating phase time intervals for phase switching. After the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into 3 floating phase time intervals for phase switching.

[0022] 5. The motor controller 10 first divides the electrical cycle into six floating-phase time intervals for phase switching. When the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into three floating-phase time intervals for phase switching. When the three-phase motor M operates for a second time, the motor controller 10 divides the electrical cycle into one floating-phase time interval for phase switching, where the second time interval is greater than the first time interval.

[0023] 6. The motor controller 10 first divides the electrical cycle into three floating phase time intervals for phase switching. After the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into one floating phase time interval for phase switching.

[0024] 7. The motor controller 10 first divides the electrical cycle into two floating phase time intervals to switch phases. After the three-phase motor M operates for a first time, the motor controller 10 divides the electrical cycle into one floating phase time interval to switch phases.

[0025] While the present invention has been described with reference to preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and similar arrangements that are obvious to those skilled in the art. Therefore, the scope of protection should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

[0026] The above descriptions are merely preferred embodiments of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the present invention.

Claims

1. A motor controller for driving a three-phase motor having a first coil, a second coil, and a third coil, wherein: The motor controller includes: a switching circuit coupled to the three-phase motor, wherein the switching circuit includes a first terminal, a second terminal, and a third terminal; a driving circuit for generating a plurality of control signals to control the switch circuit; as well as A pulse width modulation circuit is used to generate a pulse width modulation signal to the drive circuit, wherein the pulse width modulation signal has a duty cycle. The motor controller first divides an electrical cycle into N1 floating phase time intervals to switch phases. After the three-phase motor operates for a first time, the motor controller divides the electrical cycle into N2 floating phase time intervals to switch phases. Both N1 and N2 are positive integers and N1>N2. The motor controller gradually changes the duty cycle of the pulse width modulation signal at the intersection of a floating phase time interval to modulate a phase current, so that the phase current changes smoothly and reduces noise and vibration of the three-phase motor.

2. The motor controller according to claim 1, wherein: One end of the first coil is coupled to the first end, one end of the second coil is coupled to the second end, and one end of the third coil is coupled to the third end.

3. The motor controller according to claim 1, wherein: The switching circuit further comprises: a first transistor coupled to a fourth terminal and the first terminal; a second transistor coupled to a fifth terminal and the first terminal; a third transistor coupled to the fourth terminal and the second terminal; a fourth transistor coupled to the fifth terminal and the second terminal; a fifth transistor coupled to the fourth terminal and the third terminal; as well as A sixth transistor is coupled to the fifth terminal and the third terminal.

4. The motor controller according to claim 1, wherein: When the electrical cycle is divided into N1 floating phase time intervals, the three-phase motor operates in a starting state. When the electrical cycle is divided into N2 floating phase time intervals, the three-phase motor operates in a stable state.

5. The motor controller according to claim 1, wherein: The motor controller first divides the electrical cycle into 6 floating phase time intervals to switch phases. After the three-phase motor operates for the first time, the motor controller divides the electrical cycle into 1 floating phase time interval to switch phases.

6. The motor controller according to claim 1, wherein: The motor controller first divides the electrical cycle into 6 floating phase time intervals to switch phases. After the three-phase motor operates in the first time, the motor controller divides the electrical cycle into 2 floating phase time intervals to switch phases.

7. The motor controller according to claim 1, wherein: The motor controller first divides the electrical cycle into 6 floating phase time intervals to switch phases. When the three-phase motor operates for the first time, the motor controller divides the electrical cycle into 2 floating phase time intervals to switch phases. When the three-phase motor operates for a second time, the motor controller divides the electrical cycle into 1 floating phase time interval to switch phases. The second time is greater than the first time.

8. The motor controller according to claim 1, wherein: The motor controller first divides the electrical cycle into 6 floating phase time intervals to switch phases. After the three-phase motor operates in the first time, the motor controller divides the electrical cycle into 3 floating phase time intervals to switch phases.

9. The motor controller according to claim 1, wherein: The motor controller first divides the electrical cycle into 6 floating phase time intervals to switch phases. When the three-phase motor operates for the first time, the motor controller divides the electrical cycle into 3 floating phase time intervals to switch phases. When the three-phase motor operates for a second time, the motor controller divides the electrical cycle into 1 floating phase time interval to switch phases. The second time is greater than the first time.

10. The motor controller according to claim 1, wherein: The motor controller first divides the electrical cycle into three floating phase time intervals to switch phases. After the three-phase motor operates for the first time, the motor controller divides the electrical cycle into one floating phase time interval to switch phases.

11. The motor controller according to claim 1, wherein: The motor controller first divides the electrical cycle into two floating phase time intervals to switch phases. After the three-phase motor operates in the first time, the motor controller divides the electrical cycle into one floating phase time interval to switch phases.

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