CN115208274A - Motor controller - Google Patents

Abstract

A motor controller has a switch circuit and a driving circuit. The switching circuit is coupled to a three-phase motor to drive the three-phase motor. The driving circuit generates a plurality of control signals to control the switch circuit. The motor controller drives the three-phase motor by using a first pulse width modulation waveform and a second pulse width modulation waveform, wherein the first pulse width modulation waveform and the second pulse width modulation waveform have different frequencies. The motor controller detects a phase transition point by using the second PWM waveform, wherein the frequency of the first PWM waveform is greater than that of the second PWM waveform.

Description

motor controller

technical field

The present invention relates to a motor controller, and more particularly, to a motor controller applicable to a sensorless three-phase motor.

Background technique

Traditionally, three-phase motors are driven in two ways. One is through the Hall sensor to switch the phase and then drive the three-phase motor to run. The other is to drive a three-phase motor without Hall sensors. Since the Hall sensor is easily affected by the external environment, the sensing accuracy is reduced, and the installation of the Hall sensor will increase the volume and cost of the system, so a sensorless driving method is proposed to solve the above problems.

FIG. 1 is a timing chart of a conventional sensorless driving method. The PWM signal Vpw has a duty cycle. Generally, the motor controller controls the motor speed by adjusting the duty cycle. In the sensorless driving method, the motor controller will detect the back EMF of the floating phase by comparing the floating phase pin voltage Vf with the reference voltage Vr to switch phases. The motor controller can use the on-time interval of the PWM signal Vpw to detect the commutation point. Since the floating-phase pin voltage Vf changes with the PWM signal Vpw, the correct commutation point can be detected only by matching the timing of the PWM signal Vpw. As shown in FIG. 1 , the motor controller detects the commutation point before the falling edge of the PWM signal Vpw. This is because after the rising edge of the PWM signal Vpw, the floating-phase pin voltage Vf will be unstable due to switching noise, so the commutation point is detected before the falling edge of the PWM signal Vpw, so The floating phase pin voltage Vf can be in a most stable state. However, when the motor controller uses the on-time interval of the PWM signal Vpw to detect the commutation point, if the on-time interval is too small, the floating-phase pin voltage Vf will not have enough time to stabilize. It will be difficult to detect the back EMF of the floating phase.

SUMMARY OF THE INVENTION

In view of the aforementioned problems, an object of the present invention is to provide a motor controller that can easily detect a back electromotive force of a floating phase.

The motor controller is provided according to the present invention. The motor controller is used for driving 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 switch circuit, a drive circuit and a pulse width modulation circuit. The switch 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 switch circuit is coupled to the three-phase motor to drive the three-phase motor. An end of the first coil is coupled to the first end. One end of the second coil is coupled to the second end. One end of the third coil is coupled to the third end. In addition, the other end of the first coil is coupled to the other end of the second coil and the other end of the third coil. That is to say, the first coil, the second coil and the third coil are arranged in a Y-shape. 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 first transistor, the Conduction of the second transistor, the third transistor, the fourth transistor, the fifth transistor and the sixth transistor. The pulse width modulation circuit receives a first pulse width modulation signal to generate a second pulse width modulation signal to the driving circuit. The motor controller adjusts the rotational speed of the three-phase motor according to the first PWM signal.

The driving circuit can respectively generate a first voltage vector, a second voltage vector, a third voltage vector, a fourth voltage vector, a fifth voltage vector and a sixth voltage vector to the switch circuit for driving Connect two of the first coil, the second coil and the third coil. When the drive circuit generates the first voltage vector to the switch circuit, the drive circuit turns on the first transistor and the fourth transistor, and turns off the second transistor, the third transistor, the fifth transistor and The sixth transistor is used for sequentially turning on the first coil and the second coil. At this time, the floating phase is formed on the third coil. When the driving circuit generates the second voltage vector to the switching circuit, the driving circuit turns on the first transistor and the sixth transistor, and turns off the second transistor, the third transistor, the fourth transistor and The fifth transistor is used for sequentially turning on the first coil and the third coil. At this time, the floating phase is formed on the second coil. When the drive circuit generates the third voltage vector to the switch circuit, the drive circuit turns on the third transistor and the sixth transistor, and turns off the first transistor, the second transistor, the fourth transistor and The fifth transistor is used for sequentially turning on the second coil and the third coil. At this time, the floating phase is formed on the first coil. When the drive circuit generates the fourth voltage vector to the switch circuit, the drive circuit turns on the second transistor and the third transistor, and turns off the first transistor, the fourth transistor, the fifth transistor and The sixth transistor is used for sequentially turning on the second coil and the first coil. At this time, the floating phase is formed on the third coil. When the drive circuit generates the fifth voltage vector to the switch circuit, the drive circuit turns on the second transistor and the fifth transistor, and turns off the first transistor, the third transistor, the fourth transistor and The sixth transistor is used for sequentially turning on the third coil and the first coil. At this time, the floating phase is formed on the second coil. When the driving circuit generates the sixth voltage vector to the switching circuit, the driving circuit turns on the fourth transistor and the fifth transistor, and turns off the first transistor, the second transistor, the third transistor and the The sixth transistor is used for sequentially turning on the third coil and the second coil. At this time, the floating phase is formed on the first coil. Therefore, when the driving circuit switches phases according to the order of the first voltage vector, the second voltage vector, the third voltage vector, the fourth voltage vector, the fifth voltage vector and the sixth voltage vector, the It can drive the three-phase motor to rotate forward for one circle. When the driving circuit switches phases according to the sequence of the sixth voltage vector, the fifth voltage vector, the fourth voltage vector, the third voltage vector, the second voltage vector and the first voltage vector, it will drive the The three-phase motor reverses one revolution.

In order to reduce the current ripple of the three-phase motor, the motor controller can use a high frequency pulse width modulation waveform to drive the three-phase motor. When the motor controller activates a floating phase to detect a commutation point, the motor controller can switch to a low frequency PWM waveform to drive the three-phase motor, and use the low frequency PWM waveform to drive the three-phase motor. An on-time interval is used to detect a back electromotive force of the floating phase. That is to say, when the motor controller uses the on-time interval to detect the commutation point, the on-time interval can be prevented from being too small, thus making the detection easier. According to an embodiment of the present invention, the motor controller uses a first PWM waveform and a second PWM waveform to drive the three-phase motor, wherein the first PWM waveform and the second PWM waveform are used to drive the three-phase motor. PWM waveforms have different frequencies. The motor controller uses the second PWM waveform to detect a commutation point in a detection time interval, wherein the frequency of the first PWM waveform is greater than the frequency of the second PWM waveform. The motor controller uses the first PWM waveform to drive the three-phase motor in a time interval outside the detection time interval. The designer can design a PWM signal to have the first PWM waveform and the second PWM waveform, wherein the PWM signal can be coupled to the driving circuit to adjust the three-phase motor speed. In addition, the motor controller can determine whether to switch phases by detecting a back electromotive force of a floating phase. The motor controller can detect the back EMF of the floating phase by using an on-time interval of the second PWM waveform.

Description of drawings

FIG. 1 is a timing chart of a conventional sensorless driving method.

FIG. 2 is a schematic diagram of a motor controller according to an embodiment of the present invention.

FIG. 3 is a timing diagram of an embodiment of the present invention.

Description of reference numerals: 10-motor controller; VCC-terminal; GND-terminal; 100-switch circuit; 110-drive circuit; 120-pulse width modulation circuit; CMD-first pulse width modulation signal; Vp-th 2 PWM signal; 101-first transistor; 102-second transistor; 103-third transistor; 104-fourth transistor; 105-fifth transistor; 106-sixth transistor; U-first terminal; V-second endpoint; W-third endpoint; C1-first control signal; C2-second control signal; C3-third control signal; C4-fourth control signal; C5-fifth control signal; C6-th Six control signals; L1-first coil; L2-second coil; L3-third coil; M-three-phase motor; Vpw-pulse width modulation signal; Vr-reference voltage; Vf-floating phase pin voltage; Su-first driving signal; Sv-second driving signal; Sw-third driving signal; Td-detection time interval.

Detailed ways

The objects, features, and advantages of the present invention will become more apparent from the following description. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic diagram of the motor controller 10 according to an embodiment of the present invention. The motor controller 10 is used for driving 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 and a pulse width modulation circuit 120 . 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 transistor The 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 provide a first driving signal Su, a second driving signal Sv and a third driving signal Sw to drive the three-phase motor M, respectively. The first transistor 101 is coupled to a terminal VCC and a first terminal U and the second transistor 102 is coupled to a 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 fifth transistor 105 can be respectively a P-type MOSFET. The second transistor 102 , the fourth transistor 104 and the sixth transistor 106 can each be an N-type MOSFET.

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-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 for controlling the The conduction state 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 . The PWM circuit 120 receives a first PWM signal CMD to generate a second PWM signal Vp to the driving circuit 110 . The motor controller 10 adjusts the rotational speed of the three-phase motor M according to the first pulse width modulation signal CMD.

The driving circuit 110 can respectively generate a first voltage vector, a second voltage vector, a third voltage vector, a fourth voltage vector, a fifth voltage vector and a sixth voltage vector to the switching circuit 100 for driving the switching circuit 100. Two of the first coil L1, the second coil L2 and the third coil L3 are connected. When the driving circuit 110 generates the first voltage vector to the switching circuit 100, the driving circuit 110 turns on the first transistor 101 and the fourth transistor 104, and turns off the second transistor 102, the third transistor 103, the fifth transistor 105 and the third transistor 104. Six transistors 106 are used to turn on the first coil L1 and the second coil L2 in sequence. At this time, the floating phase is formed in the third coil L3. When the driving circuit 110 generates the second voltage vector to the switching circuit 100, the driving circuit 110 turns on the first transistor 101 and the sixth transistor 106, and turns off the second transistor 102, the third transistor 103, the fourth transistor 104 and the third transistor 106. Five transistors 105 are used to turn on the first coil L1 and the third coil L3 in sequence. At this time, the floating phase is formed on the second coil L2. When the driving circuit 110 generates the third voltage vector to the switching circuit 100, the driving circuit 110 turns on the third transistor 103 and the sixth transistor 106, and turns off the first transistor 101, the second transistor 102, the fourth transistor 104 and the third transistor 106. Five transistors 105 are used to turn on the second coil L2 and the third coil L3 in sequence. At this time, the floating phase is formed on the first coil L1. When the driving circuit 110 generates the fourth voltage vector to the switching circuit 100, the driving circuit 110 turns on the second transistor 102 and the third transistor 103, and turns off the first transistor 101, the fourth transistor 104, the fifth transistor 105 and the third transistor 103. Six transistors 106 are used to turn on the second coil L2 and the first coil L1 in sequence. At this time, the floating phase is formed in the third coil L3. When the driving circuit 110 generates the fifth voltage vector to the switch circuit 100, the driving circuit 110 turns on the second transistor 102 and the fifth transistor 105, and turns off the first transistor 101, the third transistor 103, the fourth transistor 104 and the first transistor 101. Six transistors 106 are used to turn on the third coil L3 and the first coil L1 in sequence. At this time, the floating phase is formed on the second coil L2. When the driving circuit 110 generates the sixth voltage vector to the switching circuit 100, the driving circuit 110 turns on the fourth transistor 104 and the fifth transistor 105, and turns off the first transistor 101, the second transistor 102, the third transistor 103 and the third transistor 105. Six transistors 106 are used to turn on the third coil L3 and the second coil L2 in sequence. At this time, the floating phase is formed on the first coil L1. Therefore, when the driving circuit 110 switches the phases according to the sequence of the first voltage vector, the second voltage vector, the third voltage vector, the fourth voltage vector, the fifth voltage vector and the sixth voltage vector, the three-phase motor M can be driven. Make a full circle. When the driving circuit 110 switches the phases according to the sequence of the sixth voltage vector, the fifth voltage vector, the fourth voltage vector, the third voltage vector, the second voltage vector and the first voltage vector, it can drive the three-phase motor M to reverse. a circle.

FIG. 3 is a timing diagram of an embodiment of the present invention. The waveforms of the first driving signal Su, the second driving signal Sv and the third driving signal Sw are all similar to an M-shaped waveform, but the phase angles differ by 120 degrees. The second driving signal Sv lags the first driving signal Su by a phase angle of 120 degrees. The third driving signal Sw lags behind the second driving signal Sv by a phase angle of 120 degrees. For example, when the first driving signal Su and the second driving signal Sv are subtracted, a waveform similar to a sine wave can be obtained. Therefore, the current waveforms flowing through the first coil L1 and the second coil L2 are also similar to the sine wave.

In order to reduce the current ripple of the three-phase motor M, the motor controller 10 can use a high frequency pulse width modulation waveform to drive the three-phase motor M. When the motor controller 10 activates a floating phase to detect a commutation point, the motor controller 10 can switch to a low-frequency PWM waveform to drive the three-phase motor M, and utilize one of the low-frequency PWM waveforms. The on-time interval is used to detect a back EMF of the floating phase. That is to say, when the motor controller 10 uses the on-time interval to detect the commutation point, the on-time interval can be prevented from being too small, thus making the detection easier. As shown in FIG. 3 , when the motor controller 10 detects the back EMF in a detection time interval Td, it can prevent the on-time interval from being too small, thereby improving the detection success rate. According to an embodiment of the present invention, the motor controller 10 uses a first PWM waveform and a second PWM waveform to drive the three-phase motor M, wherein the first PWM waveform and the second PWM waveform are used to drive the three-phase motor M. Modulated waveforms have different frequencies. The motor controller 10 uses the second PWM waveform to detect the commutation point in the detection time interval Td, wherein the frequency of the first PWM waveform is greater than the frequency of the second PWM waveform. The motor controller 10 uses the first PWM waveform to drive the three-phase motor M in a time interval other than the detection time interval Td. The designer can design a PWM signal to have a first PWM waveform and a second PWM waveform, wherein the PWM signal can be coupled to the driving circuit 110 to adjust the rotational speed of the three-phase motor M. In addition, the motor controller 10 can determine whether to switch the phase by detecting the back EMF of the floating phase. The motor controller 10 can use an on-time interval of the second PWM waveform to detect the back EMF of the floating phase.

Specifically, the second PWM signal Vp may be a multi-frequency signal. When the motor controller 10 operates in a non-floating phase mode, the second PWM signal Vp can have a first frequency and a first PWM waveform to reduce the current ripple of the three-phase motor M. When the motor controller 10 operates in a floating-phase mode, the second PWM signal Vp can have a second frequency and a second PWM waveform to improve the success rate of detecting the commutation point, wherein the first The frequency is greater than the second frequency. The motor controller 10 can determine whether to switch the phase by detecting the back EMF of the floating phase. When the motor controller 10 uses the on-time interval of the second PWM signal Vp to detect the commutation point, it can prevent the on-time interval from being too small, thus making the detection easier.

While the present invention has been described by way of illustration of the preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. To the contrary, the present invention is intended to cover various modifications and similar arrangements apparent to those skilled in the art. Accordingly, the scope of the patent application should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (17)

1. A motor controller for driving a three-phase motor, the motor controller comprising:

a switching circuit coupled to the three-phase motor to drive the three-phase motor; and

a driving circuit for generating a plurality of control signals to control the switching circuit, wherein the motor controller drives the three-phase motor by using a first pulse width modulation waveform and a second pulse width modulation waveform, and the first pulse width modulation waveform and the second pulse width modulation waveform have different frequencies.

2. The motor controller as claimed in claim 1, further comprising a pulse width modulation signal having the first pulse width modulation waveform and the second pulse width modulation waveform, the pulse width modulation signal being coupled to the driving circuit to adjust a rotation speed of the three-phase motor.

3. The motor controller as claimed in claim 1, wherein the motor controller detects a back emf of a floating phase using the second pwm waveform.

4. The motor controller as claimed in claim 1, wherein the motor controller detects a phase change point using the second pwm waveform at a detection time interval.

5. The motor controller as claimed in claim 4, wherein a frequency of the first PWM waveform is greater than a frequency of the second PWM waveform.

6. The motor controller as claimed in claim 4, wherein the motor controller drives the three-phase motor with the first PWM waveform at a time interval outside the detection time interval.

7. The motor controller of claim 1, 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 providing a first driving signal, a second driving signal and a third driving signal respectively for driving the three-phase motor.

8. The motor controller of claim 7, wherein the switching circuit further comprises:

a first transistor coupled to a fourth node and the first node;

a second transistor coupled to a fifth node and the first node;

a third transistor coupled to the fourth node and the second node;

a fourth transistor coupled to the fifth terminal and the second terminal;

a fifth transistor coupled to the fourth node and the third node; and

a sixth transistor coupled to the fifth node and the third node.

9. The motor controller of claim 7 wherein a waveform of the first driving signal is similar to an M-type waveform, a waveform of the second driving signal is similar to the M-type waveform, and a waveform of the third driving signal is similar to the M-type waveform.

10. A motor controller for driving a three-phase motor, the motor controller comprising:

a switching circuit coupled to the three-phase motor to drive the three-phase motor;

a driving circuit for generating a plurality of control signals to control the switch circuit; and

the pulse width modulation circuit is used for receiving a first pulse width modulation signal to generate a second pulse width modulation signal to the driving circuit, wherein the second pulse width modulation signal is a multi-frequency signal.

11. The motor controller of claim 10, wherein the motor controller determines whether to switch phases by detecting a back emf of a floating phase.

12. The motor controller as claimed in claim 10, wherein the motor controller detects a phase transition point by using an on-time period of the second pwm signal.

13. The motor controller as claimed in claim 10, wherein the second pwm signal has a first frequency and a first pwm waveform when the motor controller operates in a non-floating phase mode, and a second frequency and a second pwm waveform when the motor controller operates in a floating phase mode.

14. The motor controller of claim 13 wherein the first frequency is greater than the second frequency.

15. The motor controller of claim 10 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 providing a first driving signal, a second driving signal and a third driving signal respectively for driving the three-phase motor.

16. The motor controller of claim 15, wherein the switching circuit further comprises:

a first transistor coupled to a fourth node and the first node;

a second transistor coupled to a fifth node and the first node;

a third transistor coupled to the fourth node and the second node;

a fourth transistor coupled to the fifth node and the second node;

a fifth transistor coupled to the fourth node and the third node; and

a sixth transistor coupled to the fifth node and the third node.

17. The motor controller of claim 15 wherein a waveform of the first driving signal is similar to an M-type waveform, a waveform of the second driving signal is similar to the M-type waveform, and a waveform of the third driving signal is similar to the M-type waveform.

Images