Motor controller

Abstract

A motor controller has a switch circuit, a drive circuit, a pulse width modulation circuit and a Hall sensor. The switch circuit is coupled to a three-phase motor to drive the three-phase motor. The drive circuit generates a plurality of control signals to control the switch circuit. The pulse width modulation circuit generates a pulse width modulation signal to the drive circuit. The pulse width modulation signal has a duty cycle. The Hall sensor is coupled to the pulse width modulation circuit to generate a Hall signal. When the duty cycle is less than a positioning duty cycle, the motor controller generates a positioning waveform according to an initial value of the Hall signal. The positioning waveform may be a portion of an M-shaped wave.

Description

Technical Field

[0001] The present invention relates to a motor controller, and more particularly to a motor controller capable of starting a three-phase motor via a Hall sensor. Background Art

[0002] Traditionally, there are two ways to drive a three-phase motor. One is to drive the three-phase motor by switching phases through a Hall sensor. The other is to drive the three-phase motor without a Hall sensor. The early method was to use three Hall sensors to drive the three-phase motor. In recent years, in order to reduce system costs and solve the matching problem of three Hall sensors, the driving method with only one Hall sensor has gradually become popular. However, since a single Hall sensor cannot clearly know the fan position, a starting method is required to enable the three-phase motor to operate smoothly.

[0003] U.S. Patent No. 9,793,839 discloses a motor control circuit, which uses a Hall sensor to sense the magnetic pole position of a three-phase motor, and executes a phase switching mechanism through a start controller and an operation controller to drive the three-phase motor from a start state to a normal operation state. In the start state, the start controller controls a switching time and controls a storage to sequentially transmit the digital model required for phase switching to the operation controller. The operation controller performs phase switching of the full-bridge circuit according to the received digital model to operate the three-phase motor. In the normal operation state, the start controller stops transmitting the digital model of phase switching to the operation controller. The operation controller sequentially captures 6 sets of digital models every switching time, and executes phase switching of the full-bridge circuit accordingly to operate the three-phase motor. However, this start method is too ideal and difficult to match with the three-phase motor, thus increasing the difficulty of starting the three-phase motor and reducing the success rate of starting the three-phase motor. Summary of the invention

[0004] In view of the above problems, an object of the present invention is to provide a motor controller that can start a three-phase motor through a Hall sensor, and the motor controller can improve the success rate of starting the three-phase motor.

[0005] According to the present invention, a motor controller is provided. The motor controller is used to drive the 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, a pulse width modulation circuit and a Hall sensor. The switching circuit is coupled to the three-phase motor to drive the three-phase motor. The switching circuit has a first terminal, a second terminal and a third terminal, wherein the first terminal, the second terminal and the third terminal respectively provide a first driving signal, a second driving signal and a third driving signal to drive the three-phase motor. The driving circuit generates a plurality of control signals to control the switching circuit. The pulse width modulation circuit generates a pulse width modulation signal to the driving circuit. The pulse width modulation signal has a duty cycle. The Hall sensor is coupled to the pulse width modulation circuit to detect a magnetic pole position of the three-phase motor and generate a Hall signal to the pulse width modulation circuit to switch the phase.

[0006] According to an embodiment of the present invention, the starting method of the three-phase motor can be divided into the following four stages:

[0007] 1. In order to start the three-phase motor smoothly, the duty cycle will gradually increase from 0. When the duty cycle is less than a positioning duty cycle, the motor controller will generate a positioning waveform according to the initial value of the Hall signal, wherein a first time point is the time point when the duty cycle is equal to the positioning duty cycle. The positioning waveform can be a part of an M-shaped wave.

[0008] 2. When the duty cycle is greater than the positioning duty cycle, the motor controller generates a series of pre-set waveforms at a first forced commutation time to the first drive signal, the second drive signal and the third drive signal, thereby driving the three-phase motor to obtain a first commutation point, wherein the first commutation point is the time point at which the Hall signal first changes its level and the first commutation point is greater than the first time point. The pre-set waveform may be a part of the M-shaped wave.

[0009] 3. When the first commutation point appears, the motor controller generates a plurality of waveforms corresponding to the first commutation point to the first drive signal, the second drive signal and the third drive signal respectively. Then, the motor controller generates a series of pre-set waveforms to the first drive signal, the second drive signal and the third drive signal respectively at a second forced commutation time, thereby driving the three-phase motor to obtain a second commutation point, wherein the second commutation point is the time point when the Hall signal changes level for the second time and the second commutation point is greater than the first commutation point. The pre-set waveform may be a part of the M-shaped wave. The motor controller operates in a startup mode before the second commutation point.

[0010] 4. When the second switching point appears, the motor controller generates multiple waveforms corresponding to the second switching point to the first drive signal, the second drive signal and the third drive signal respectively. The motor controller operates in a normal drive mode after the second switching point. The motor controller can obtain an initial switching time and a third switching point based on the first switching point and the second switching point, wherein the third switching point is the time point when the Hall signal changes level for the third time and the third switching point is greater than the second switching point. The motor controller can greatly improve the success rate of starting the three-phase motor through this four-stage starting method. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. 4 is a schematic diagram of a motor controller according to an embodiment of the present invention.

[0012] Figure 2 FIG. 1 is a first timing diagram of an embodiment of the present invention.

[0013] Figure 3 FIG. 4 is a second timing diagram of an embodiment of the present invention.

[0014] Explanation of the accompanying drawings: 10-motor controller; VCC-endpoint; GND-endpoint; 100-switching circuit; 110-driving circuit; 120-pulse width modulation circuit; 130-Hall sensor; Vp pulse width modulation signal; Vh Hall signal; 101-first transistor; 102-second transistor; 103-third transistor; 104-fourth transistor; 105-fifth transistor; 106-sixth transistor; U-first end point; V-second end point; W-third end point; C1-first control signal; C2-second control signal; C3-third control 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; Su-first drive signal; Sv second drive signal; Sw third drive signal; T1-first time point; Tp1-first switching point; Tp2-second switching point; Tp3-third switching point. DETAILED DESCRIPTION

[0015] The following description will make the purpose, features, and advantages of the present invention more apparent. The preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0016] Figure 1Schematic 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 has a switch circuit 100, a drive circuit 110, a pulse width modulation circuit 120 and a Hall sensor 130. The switch circuit 100 has 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, wherein the switch circuit 100 is coupled to the three-phase motor M to drive the three-phase motor M. The first terminal U, the second terminal V and the third terminal W respectively provide a first drive signal Su, a second drive signal Sv and a third drive signal Sw to drive the three-phase motor M. The first transistor 101 is coupled to a terminal VCC and the first terminal U, and 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, and 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, and 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 be a P-type metal oxide semiconductor transistor respectively. The second transistor 102, the fourth transistor 104 and the sixth transistor 106 can be an N-type metal oxide semiconductor transistor respectively.

[0017] One end of the first coil L1 is coupled to the first end U. One end of the second coil L2 is coupled to the second end V. One end of the third coil L3 is coupled to the third end W. In addition, 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. That is, the first coil L1, the second coil L2 and the third coil L3 are arranged in a Y-shaped manner. 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, which are used to control the switching states of the first transistor 101, the second transistor 102, the third transistor 103 and 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, wherein the pulse width modulation signal Vp is used to adjust the speed of the three-phase motor M. The pulse width modulation signal Vp has a duty cycle. The Hall sensor 130 is coupled to the PWM circuit 120 to detect a magnetic pole position of the three-phase motor M and generate a Hall signal Vh to the PWM circuit 120 to switch the phase. Since the method of driving the three-phase motor is known to those skilled in the art, it will not be described in detail here.

[0018] According to an embodiment of the present invention, the starting method of the three-phase motor M can be divided into the following four stages:

[0019] 1. In order to smoothly start the three-phase motor M, the duty cycle of the PWM signal Vp will gradually increase from 0. When the duty cycle is less than a positioning duty cycle, the motor controller 10 will generate different positioning waveforms according to the initial value of the Hall signal Vh. Figure 2 1 is a first timing diagram of an embodiment of the present invention. The first timing diagram shows the waveforms of the first drive signal Su, the second drive signal Sv and the third drive signal Sw generated by the motor controller 10 when the initial value of the Hall signal Vh is a low level, wherein the first time point T1 is the time point when the duty cycle is equal to the positioning duty cycle. Figure 3 1 is a second timing diagram of an embodiment of the present invention. The second timing diagram shows the waveforms of the first driving signal Su, the second driving signal Sv and the third driving signal Sw generated by the motor controller 10 when the initial value of the Hall signal Vh is a high level. Figure 2 and Figure 3 As shown, the positioning waveform can be part of an M-shaped wave.

[0020] 2. When the duty cycle is greater than the positioning duty cycle, the motor controller 10 generates a series of pre-set waveforms at a first forced commutation time to the first drive signal Su, the second drive signal Sv and the third drive signal Sw, thereby driving the three-phase motor M to obtain a first commutation point Tp1, wherein the first commutation point Tp1 is the time point when the Hall signal Vh changes its level for the first time and Tp1>T1. Figure 2 and Figure 3 As shown, the predetermined waveform may be a portion of an M-shaped wave.

[0021] 3. When the first switching point Tp1 appears, the motor controller 10 generates a plurality of waveforms corresponding to the first switching point Tp1 to the first drive signal Su, the second drive signal Sv and the third drive signal Sw. Then, the motor controller 10 generates a series of pre-set waveforms to the first drive signal Su, the second drive signal Sv and the third drive signal Sw at a second forced switching time, thereby driving the three-phase motor M to obtain a second switching point Tp2, wherein the second switching point Tp2 is the time point when the Hall signal Vh changes its level for the second time and Tp2>Tp1. Figure 2 and Figure 3 As shown, the preset waveform may be a portion of an M-shaped wave. The motor controller 10 operates in a start-up mode before the second switching point Tp2.

[0022] 4. When the second switching point Tp2 appears, the motor controller 10 generates multiple waveforms corresponding to the second switching point Tp2 to the first drive signal Su, the second drive signal Sv and the third drive signal Sw. The motor controller 10 operates in a normal drive mode after the second switching point Tp2. The motor controller 10 can obtain an initial switching time and a third switching point Tp3 according to the first switching point Tp1 and the second switching point Tp2, wherein the third switching point Tp3 is the time point when the Hall signal Vh changes its level for the third time and Tp3>Tp2. The motor controller 10 can greatly improve the success rate of starting the three-phase motor M through this four-stage starting method.

[0023] Although the present invention has been described by way of example with preferred embodiments, it should be understood that the present invention is not limited to the disclosed embodiments. On the contrary, the present invention is intended to cover various modifications and similar configurations that are obvious to those skilled in the art. Therefore, the scope of protection should be interpreted in the broadest sense to include all such modifications and similar configurations.

[0024] The above description is only a preferred embodiment 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, characterized in that: The three-phase motor has a first coil, a second coil and a third coil. The motor controller includes: a switch circuit coupled to the three-phase motor, wherein the switch circuit comprises a first terminal, a second terminal and a third terminal, the first terminal, the second terminal and the third terminal respectively provide a first drive signal, a second drive signal and a third drive signal to drive the three-phase motor; a driving circuit for generating a plurality of control signals to control the switch circuit; a pulse width modulation circuit for generating a pulse width modulation signal to the driving circuit, wherein the pulse width modulation signal has a duty cycle; and A Hall sensor is used to generate a Hall signal to the pulse width modulation circuit, wherein when the working cycle is less than a positioning working cycle, the motor controller generates a positioning waveform according to an initial value of the Hall signal, and when the working cycle is greater than the positioning working cycle, the motor controller generates a series of pre-set waveforms to the first drive signal, the second drive signal and the third drive signal at a first forced switching time, thereby driving the three-phase motor to obtain a first switching point.

2. The motor controller according to claim 1, characterized in that: The positioning waveform is a portion of an M-shaped wave.

3. The motor controller according to claim 1, characterized in that: 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.

4. The motor controller according to claim 1, characterized in that: The switch 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.

5. The motor controller according to claim 1, characterized in that: The preset waveform is a portion of an M-shaped wave.

6. The motor controller according to claim 1, characterized in that: When the first switching point appears, the motor controller generates a plurality of waveforms corresponding to the first switching point to the first driving signal, the second driving signal and the third driving signal respectively.

7. The motor controller according to claim 6, characterized in that: The motor controller generates a series of preset waveforms to the first drive signal, the second drive signal and the third drive signal at a second forced commutation time, thereby driving the three-phase motor to obtain a second commutation point, which is greater than the first commutation point.

8. The motor controller according to claim 7, characterized in that: The motor controller operates in a start-up mode before the second switching point.

9. The motor controller according to claim 8, characterized in that: When the second switching point appears, the motor controller generates a plurality of waveforms corresponding to the second switching point to the first driving signal, the second driving signal and the third driving signal respectively.

10. The motor controller according to claim 9, characterized in that: The motor controller operates in a normal driving mode after the second switching point.

11. The motor controller according to claim 10, characterized in that: The motor controller obtains an initial switching time and a third switching point according to the first switching point and the second switching point. The third switching point is greater than the second switching point.

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