motor controller

Abstract

A motor controller includes a switching circuit, a control unit, and a pulse width modulation signal having a duty cycle. The motor controller is configured to drive a motor having a coil. The switching circuit is configured to provide a coil current to the coil. The control unit is configured to generate control signals to control the switching circuit. When the motor controller enters a position initialization state, the motor controller causes the coil current to reach a predetermined value within an electrical cycle. When the coil current reaches the predetermined value, the control unit records the duty cycle. The motor controller is configured to improve a success rate of starting the motor.

Description

Technical Field

[0001] This invention relates to a motor controller, and more particularly to a motor controller that can improve the success rate of starting a motor. Background Technology

[0002] Traditionally, motor driving methods can be divided into two types. One type uses Hall sensors to switch phases to drive the motor. The other type drives the motor without a Hall sensor. Because Hall sensors are easily affected by external environmental factors, causing a decrease in sensing accuracy, and because installing Hall sensors increases the size and cost of the system, sensorless driving methods have been proposed to solve these problems.

[0003] In sensorless drive methods, designers adjust motor parameters under a specific power supply voltage. When the power supply voltage changes, if it is too high, it will cause excessive coil current. If the power supply voltage is too low, the motor will not reach the required speed, leading to start-up failure. Therefore, a motor controller is needed that can protect the motor coils and improve the success rate of motor starting under different power supply voltages. Summary of the Invention

[0004] In view of the aforementioned problems, the object of the present invention is to provide a motor controller that can improve the success rate of starting a motor.

[0005] According to the present invention, a motor controller is provided. The motor controller is used to drive a motor, wherein the motor may be a three-phase motor. The motor has a first coil, a second coil, and a third coil. The motor controller includes a switching circuit, a control unit, and a detection unit. 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 motor to drive the motor. 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 motor. The first transistor is coupled to the fourth terminal and the first terminal, and the second transistor is coupled to the first terminal and the fifth terminal. The third transistor is coupled to the fourth terminal and the second terminal, and the fourth transistor is coupled to the second terminal and the fifth terminal. The fifth transistor is coupled to the fourth terminal and the third terminal, and the sixth transistor is coupled to the third terminal and the fifth terminal. The system can provide a power supply voltage to the motor controller via the fourth terminal, enabling the motor controller to operate normally.

[0006] One 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. 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, the first coil, the second coil, and the third coil are arranged in a Y-shape. The control unit 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 to control the conduction of the first transistor, the second transistor, the third transistor, the fourth transistor, the fifth transistor, and the sixth transistor, respectively. The detection unit is coupled to the first end, the second end, and the third end to generate a first detection signal and a second detection signal to the control unit. The detection unit can be used to detect a current in the first coil and a back electromotive force of a floating phase. The switching circuit is used to provide the current in the first coil to the first coil. In addition, the motor controller further includes a pulse width modulation signal, wherein the pulse width modulation signal has a duty cycle. The control unit receives the pulse width modulation signal to adjust a speed of the motor.

[0007] First, when the motor is stationary, the motor controller generates a set of fixed voltage waveforms to the first, second, and third terminals, respectively, so that the first, second, and third drive signals can be either a six-step square wave signal or a sine wave signal to drive the motor. At this time, the motor controller enters an initial positioning state and causes the duty cycle of the pulse width modulation signal to change rapidly, so that the current of the first coil can quickly reach a predetermined value within one electrical cycle. When the current of the first coil reaches the predetermined value, the detection unit causes the first detection signal to change from a low level to a high level to notify the control unit to record the duty cycle. Then, the motor controller causes the duty cycle to gradually decrease at a very slow rate to stabilize the motor. Afterward, the motor controller causes the motor to begin accelerating. Based on the recorded duty cycle, the motor controller can ensure that the current of the first coil in a startup procedure is less than or equal to a multiple of the predetermined value, where the multiple can be greater than or equal to 1. When the motor reaches a predetermined speed, the motor controller activates a floating phase to detect a commutation point, wherein the floating phase is formed in the first coil. When the detection unit detects a zero-crossing point of a back electromotive force, the detection unit causes the second detection signal to change from a low level to a high level to notify the control unit to perform a commutation procedure. Therefore, the motor controller can protect the first coil under different power supply voltages and improve the success rate of starting the motor. Attached Figure Description

[0008] Figure 1This is a schematic diagram of a motor controller according to an embodiment of the present invention.

[0009] Figure 2 This is a timing diagram of an embodiment of the present invention.

[0010] Explanation of reference numerals in the attached diagram: 10-Motor controller; 100-Switching circuit; 110-Control unit; 120-Detection unit; 101-First transistor; 102-Second transistor; 103-Third transistor; 104-Fourth transistor; 105-Fifth transistor; 106-Sixth transistor; W-First terminal; U-Second terminal; V-Third terminal; VCC-Fourth terminal; GND-Fifth terminal; 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-Motor; ILW-Current of first coil L1; Vp-Pulse width modulation signal; Vd1-First detection signal; Vd2-Second detection signal; WO-First drive signal; UO-Second drive signal; VO-Third drive signal; CL-Preset value. Detailed Implementation

[0011] The objects, features, and advantages of the invention will become more apparent from the following description. Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings.

[0012] Figure 1This 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 motor M, wherein 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 controller 10 has a switching circuit 100, a control unit 110, and a detection unit 120. The switching 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 W, a second terminal U, and a third terminal V, wherein the switching circuit 100 is coupled to the motor M to drive the motor M. The first terminal W, the second terminal U, and the third terminal V respectively provide a first drive signal WO, a second drive signal UO, and a third drive signal VO to drive the motor M. The first transistor 101 is coupled to a fourth terminal VCC and the first terminal W, while the second transistor 102 is coupled to the first terminal W and a fifth terminal GND. The third transistor 103 is coupled to the fourth terminal VCC and the second terminal U, while the fourth transistor 104 is coupled to the second terminal U and the fifth terminal GND. The fifth transistor 105 is coupled to the fourth terminal VCC and the third terminal V, while the sixth transistor 106 is coupled to the third terminal V and the fifth terminal GND. The system can provide a power supply voltage to the motor controller 10 via the fourth terminal VCC, enabling the motor controller 10 to operate normally. The first transistor 101, the third transistor 103, and the fifth transistor 105 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.

[0013] One end of the first coil L1 is coupled to the first end W. One end of the second coil L2 is coupled to the second end U. One end of the third coil L3 is coupled to the third end V. The other end of the first coil L1 is coupled to the other ends of the second coil L2 and 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 control unit 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 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 detection unit 120 is coupled to the first end W, the second end U, and the third end V to generate a first detection signal Vd1 and a second detection signal Vd2 to the control unit 110. The detection unit 120 can be used to detect the current ILW of the first coil L1 and the back electromotive force of a floating phase. The switching circuit 100 is used to provide the current ILW of the first coil L1 to the first coil L1. In addition, the motor controller 10 has a pulse width modulation signal Vp, wherein the pulse width modulation signal Vp has a duty cycle. The control unit 110 receives the pulse width modulation signal Vp to adjust the speed of the motor M.

[0014] Figure 2This is a timing diagram of an embodiment of the present invention. First, when the motor M is in a stationary state, the motor controller 10 generates a set of fixed voltage waveforms to the first terminal W, the second terminal U, and the third terminal V, respectively, so that the first drive signal WO, the second drive signal UO, and the third drive signal VO can be a six-step square wave signal or a sine wave signal to drive the motor M. At this time, the motor controller 10 enters a positioning initial state and causes the working cycle of the pulse width modulation signal Vp to change rapidly, so that the current ILW of the first coil L1 can quickly reach a predetermined value CL within one electrical cycle. When the current ILW of the first coil L1 reaches the predetermined value CL, the detection unit 120 causes the first detection signal Vd1 to change from a low level to a high level to notify the control unit 110 to record the working cycle. Then, the motor controller 10 causes the working cycle to gradually decrease at a very slow rate to stabilize the motor M. After that, the motor controller 10 causes the motor M to start accelerating. By recording the operating cycle, the motor controller 10 ensures that the current ILW of the first coil L1 is less than or equal to a predetermined value CL during a startup procedure, where the multiple can be greater than or equal to 1. When the speed of the motor M reaches a predetermined speed, the motor controller 10 activates a floating phase to detect a commutation point, wherein the floating phase is formed in the first coil L1. When the detection unit 120 detects a zero-crossing point of a back electromotive force, the detection unit 120 changes the second detection signal Vd2 from a low level to a high level to notify the control unit 110 to perform a commutation procedure. Therefore, the motor controller 10 can protect the first coil L1 under different power supply voltages and improve the success rate of starting the motor M. In addition, the motor controller 10 can additionally set a predetermined number of rotations to determine whether to activate the floating phase to detect the commutation point. The motor controller 10 will only allow the floating phase to be activated to detect the commutation point after the motor M has rotated to the predetermined number of rotations.

[0015] To improve the success rate of starting the motor M, the motor controller 10 is designed to successfully complete the starting procedure under different output loads. That is, the electrical cycle, predetermined value CL, predetermined speed, and predetermined number of rotations in the initial positioning phase can all be variable values. For example, when the motor M is under light load, the electrical cycle in the initial positioning phase can be a smaller value. When the motor M is under heavy load, the electrical cycle in the initial positioning phase can be a larger value, allowing sufficient time for the motor M to stabilize. When the motor M is under light load, the predetermined number of rotations can be a smaller value. When the motor M is under heavy load, the predetermined number of rotations can be a larger value.

[0016] One embodiment of the present invention utilizes a current-limiting technique to enable a coil current to quickly reach a predetermined value within one electrical cycle and simultaneously record one operating cycle. This current-limiting technique allows a motor controller to protect a motor coil under different power supply voltages and improves the success rate of starting the motor. The motor controller can be applied to a single-phase motor or a multi-phase motor.

[0017] While the invention has been described by way of example through preferred embodiments, it should be understood that the invention is not limited to the embodiments disclosed herein. Rather, the invention is intended to cover various modifications and similar configurations that will be apparent to those skilled in the art. Therefore, its scope should be interpreted in the broadest sense to include all such modifications and similar configurations.

[0018] 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 be included in the scope of the present invention.

Claims

1. A motor controller, characterized in that, The motor controller is used to drive a motor having a coil, and the motor controller includes: A switching circuit is used to provide current to a coil. A control unit for generating multiple control signals to control the switching circuit; and A pulse width modulation (PWM) signal, wherein the PWM signal has a working cycle, when the motor is in a stationary state, the motor controller generates a set of fixed voltage waveforms to a first terminal, a second terminal, and a third terminal respectively, so that a first drive signal, a second drive signal, and a third drive signal are a six-step square wave signal or a sine wave signal to drive the motor. At this time, the motor controller enters a positioning initial state and causes the working cycle of the PWM signal to change rapidly, so that the coil current reaches a predetermined value within one electrical cycle. When the coil current reaches the predetermined value, the control unit records the working cycle.

2. The motor controller as described in claim 1, characterized in that, This motor controller is used to improve the success rate of starting the motor.

3. The motor controller as described in claim 1, characterized in that, When the motor reaches a predetermined speed, the motor controller activates a floating phase to detect a commutation point.

4. The motor controller as described in claim 1, characterized in that, Once the motor has rotated a predetermined number of revolutions, the motor controller will allow a floating phase to be activated to detect a commutation point.

5. The motor controller as described in claim 1, characterized in that, The motor controller makes an electrical cycle of a certain period of time during the initial positioning phase a variable value.

6. The motor controller as described in claim 1, characterized in that, The motor controller further includes a detection unit for generating a first detection signal and a second detection signal to the control unit.

7. The motor controller as described in claim 1, characterized in that, This motor controller is designed for use with a single-phase motor or a multi-phase motor.

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