Motor controller

Abstract

The present invention discloses a motor controller having a switching circuit and a control unit. The switching circuit is coupled to a motor to drive the motor. The control unit generates a control signal to control the switching circuit. The motor controller determines a non-excitation time. When the motor is in a stalled state, the motor controller sets the non-excitation time to a variable value. The motor controller utilizes the non-excitation time to achieve a stall protection function. The motor controller determines whether the motor is in the stalled state by detecting a rotor speed or a rotor temperature. In addition, the motor controller also has a drive signal, wherein the drive signal has the non-excitation time.

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, motor drive methods can be categorized into two types. One uses Hall effect sensors to switch phases and drive the motor. The other operates without Hall effect sensors. Because Hall effect sensors are susceptible to environmental influences, resulting in reduced sensing accuracy, and the inclusion of Hall effect sensors increases system size and cost, sensorless drive methods have been proposed to address these issues. In this sensorless drive method, the motor controller detects the back EMF of the floating phase to switch phases and drive the motor.

[0003] Figure 1 The following is a timing diagram of a conventional drive signal Vd, wherein the drive signal Vd has an excitation time and a de-excitation time. When an external force causes the motor rotor to become stuck in a certain position, the motor coil will continue to output power, causing the temperature to rise excessively. In this case, the conventional technology uses a fixed excitation time and a fixed de-excitation time to achieve a stall protection function. When the motor operates during the excitation time, the temperature rises. Conversely, when the motor operates during the de-excitation time, the temperature drops. Therefore, the motor controller sets the de-excitation time to be longer than the excitation time to achieve the purpose of reducing the temperature. However, if the motor controller fails to successfully start the motor the first time, it must wait for the de-excitation time before restarting, resulting in a long startup time. Therefore, when the motor is in a stalled state, a new technology is needed to increase the number of restarts within a limited time and improve the startup success rate. 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 increase the number of restarts within a limited time and improve a success rate of restarts.

[0005] According to the present invention, a motor controller is provided. The motor controller is used to drive a motor. The motor controller includes a switching circuit, a control circuit, a stall protection unit, a rotor detection unit, a non-excitation time modulation unit, a counting unit, an input voltage detection unit, and a temperature detection unit. The switching circuit is coupled to the motor to drive the motor. The control unit generates a control signal to the switching circuit to control the switching circuit. The rotor detection unit generates a first detection signal to the stall protection unit to inform the stall protection unit whether the motor is in a stalled state. For example, the rotor detection unit can determine whether the motor is in a stalled state by detecting a rotor speed or a rotor temperature. The stall protection unit is coupled to the control unit to generate a drive signal to the control unit, wherein the drive signal has an excitation time and a non-excitation time. When the motor is in the stalled state, the motor controller can set the excitation time to a fixed value and the non-excitation time to a variable value to achieve a stall protection function. The non-excitation time modulation unit generates a timing signal to the stall protection unit to indicate the non-excitation time. For example, the drive signal may have a first excitation time, a first non-excitation time, a second excitation time, a second non-excitation time, a third excitation time, and a third non-excitation time. The motor controller may make the first excitation time equal to the second excitation time and the second excitation time equal to the third excitation time. The motor controller may make the second non-excitation time greater than the first non-excitation time and the third non-excitation time greater than the second non-excitation time. Through this control mechanism, the motor controller may increase the number of restarts within the limited time and improve the startup success rate. In other words, the motor controller may solve a delayed startup problem and improve the efficiency of a system. In addition, the motor controller may make the second non-excitation time greater than the second excitation time and the third non-excitation time greater than the third excitation time, so as to reduce the temperature and achieve the stall protection function. The present invention may have at least three or more embodiments as follows:

[0006] 1. The motor controller changes the non-excitation time with the number of times. When the motor is in the stalled state, the motor controller can make the non-excitation time of the first time a smaller value and the non-excitation time of the second time a larger value. That is to say, the larger the number of times, the larger the non-excitation time. The counting unit can generate a counting signal to the non-excitation time modulation unit to indicate the number of times. The non-excitation time modulation unit can modulate the non-excitation time according to the counting signal. After the motor controller successfully starts the motor, the counting unit can be reset to recalculate the number of times. For example, the non-excitation time of the first time can be 5 seconds and the non-excitation time of the Nth time can be 10 seconds, where N is a positive integer greater than 1.

[0007] 2. The motor controller causes the non-excitation time to vary with an input voltage, wherein the input voltage may be a power supply voltage. The input voltage detection unit may generate a second detection signal to the non-excitation time modulation unit to indicate the input voltage. The non-excitation time modulation unit may modulate the non-excitation time based on the second detection signal. The larger the input voltage, the longer the non-excitation time. For example, when the input voltage is a first voltage, the non-excitation time may be 5 seconds. When the input voltage is a second voltage, the non-excitation time may be 10 seconds, wherein the second voltage is greater than the first voltage.

[0008] 3. The motor controller causes the de-excitation time to vary with temperature. The temperature detection unit can generate a third detection signal to the de-excitation time modulation unit to indicate the temperature. The de-excitation time modulation unit can modulate the de-excitation time based on the third detection signal. As the temperature increases, the de-excitation time increases. For example, when the temperature is 25°C, the de-excitation time can be 5 seconds. When the temperature is 80°C, the de-excitation time can be 10 seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a timing diagram of the existing driving signal.

[0010] Figure 2 FIG. 1 is a schematic diagram of a motor controller according to an embodiment of the present invention.

[0011] Figure 3 FIG. 4 is a timing diagram of a driving signal according to an embodiment of the present invention.

[0012] Figure 4 FIG. 4 is a diagram showing the relationship between the non-excitation time and the number of times according to the first embodiment of the present invention.

[0013] Figure 5 FIG. 4 is a diagram showing the relationship between the non-excitation time and the input voltage according to the second embodiment of the present invention.

[0014] Figure 6 FIG. 4 is a diagram showing the relationship between the non-excitation time and the temperature according to the third embodiment of the present invention.

[0015] Explanation of the accompanying symbols: 10-motor controller; M-motor; 100-switching circuit; 110-control unit; 120-stall protection unit; 130-rotor detection unit; 140-non-excitation time modulation unit; 150-counting unit; 160-input voltage detection unit; 170-temperature detection unit; Vc-control signal; Vd-drive signal; Vt-timing signal; Vde1-first detection signal; Vde2-second detection signal; Vde3-third detection signal; Vco-counting signal; N-number; V1-first voltage; V2-second voltage. DETAILED DESCRIPTION

[0016] 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.

[0017] Figure 2 The figure shows a schematic diagram of a motor controller 10 according to an embodiment of the present invention, wherein the motor controller 10 is used to drive a motor M. The motor controller 10 includes a switching circuit 100, a control circuit 110, a stall protection unit 120, a rotor detection unit 130, a non-excitation time modulation unit 140, a counting unit 150, an input voltage detection unit 160, and a temperature detection unit 170. The switching circuit 100 is coupled to the motor M to drive the motor M. The motor M has a rotor and can be a three-phase motor. If the motor M is a three-phase motor, the switching circuit 100 can include three half-bridge circuits to drive the motor M. The control unit 110 generates a control signal Vc to the switching circuit 100 for controlling the switching circuit 100. The rotor detection unit 130 generates a first detection signal Vde1 to the stall protection unit 120 to inform the stall protection unit 120 whether the motor M is in a stalled state. For example, the rotor detection unit 130 can determine whether the motor M is in a stalled state by detecting the rotor speed or the rotor temperature. The stall protection unit 120 is coupled to the control unit 110 to generate a drive signal Vd to the control unit 110, wherein the drive signal Vd has an excitation time and a de-excitation time. When the motor M is in a stalled state, the motor controller 10 can set the excitation time to a fixed value and the de-excitation time to a variable value to achieve a stall protection function. The de-excitation time modulation unit 140 generates a timing signal Vt to the stall protection unit 120 to represent the de-excitation time. Figure 3 This is a timing diagram of the drive signal Vd according to an embodiment of the present invention. For example, the drive signal Vd may have a first excitation time, a first non-excitation time, a second excitation time, a second non-excitation time, a third excitation time, and a third non-excitation time. The motor controller 10 may make the first excitation time equal to the second excitation time and the second excitation time equal to the third excitation time. The motor controller 10 may make the second non-excitation time greater than the first non-excitation time and the third non-excitation time greater than the second non-excitation time. Through this control mechanism, the motor controller 10 may increase the number of restarts within a limited time and improve a startup success rate. In other words, the motor controller 10 can solve a delayed startup problem and improve the efficiency of the system. In addition, the motor controller 10 may make the second non-excitation time greater than the second excitation time and the third non-excitation time greater than the third excitation time, so as to reduce the temperature and achieve the function of stall protection. The present invention may have at least three or more embodiments as follows:

[0018] 1. The motor controller 10 varies the de-excitation time based on the number of times. When the motor M is in a stalled state, the motor controller 10 may set the de-excitation time for the first time to a shorter value and the second time to a longer value. In other words, the de-excitation time increases with the number of times. The counting unit 150 may generate a count signal Vco to the de-excitation time modulation unit 140 to indicate the number of times. The de-excitation time modulation unit 140 may adjust the de-excitation time based on the count signal Vco. When the motor controller 10 successfully starts the motor M, the counting unit 150 may be reset to recalculate the number of times. Figure 4 The figure shows the relationship between the non-excitation time and the number of times in the first embodiment of the present invention. For example, the first non-excitation time can be 5 seconds and the Nth non-excitation time can be 10 seconds, where N is a positive integer greater than 1. Figure 4 As shown, the non-excitation time can be proportional to the number of restarts. By gradually increasing the non-excitation time, the motor controller 10 can increase the number of restarts within a limited time and achieve a stall protection function.

[0019] Second, the motor controller 10 varies the de-excitation time with an input voltage, which can be a power supply voltage. The input voltage detection unit 160 generates a second detection signal Vde2 to the de-excitation time modulation unit 140, indicating the input voltage. The de-excitation time modulation unit 140 modulates the de-excitation time based on the second detection signal Vde2. The de-excitation time increases with increasing input voltage. Figure 5 The figure is a relationship diagram between the non-excitation time and the input voltage of the second embodiment of the present invention. For example, when the input voltage is a first voltage V1, the non-excitation time can be 5 seconds. When the input voltage is a second voltage V2, the non-excitation time can be 10 seconds, wherein the second voltage V2 is greater than the first voltage V1. Figure 5 As shown, the non-excitation time is proportional to the input voltage. Therefore, when the input voltage is low, the motor controller 10 can increase the number of restarts within a limited time and achieve a stall protection function.

[0020] 3. The motor controller 10 varies the de-excitation time with temperature. The temperature detection unit 170 generates a third detection signal Vde3 to the de-excitation time modulation unit 140 to indicate the temperature. The de-excitation time modulation unit 140 modulates the de-excitation time based on the third detection signal Vde3. As the temperature increases, the de-excitation time increases. Figure 6 The figure is a relationship diagram between the non-excitation time and temperature of the third embodiment of the present invention. For example, when the temperature is 25°C, the non-excitation time can be 5 seconds. When the temperature is 80°C, the non-excitation time can be 10 seconds. Figure 6As shown, the non-excitation time is directly proportional to the temperature. Therefore, when the temperature is very low, the motor controller 10 can increase the number of restarts within a limited time and achieve a stall protection function.

[0021] Specifically, designers can implement three embodiments, two of the three embodiments, or one of the three embodiments based on actual needs. According to one embodiment of the present invention, a motor controller 10 can be applied to a sensorless motor. The motor controller 10 determines an excitation time and a de-excitation time. When the motor M is in a stalled state, the motor controller 10 can set the de-excitation time to a variable value. The motor controller 10 utilizes the de-excitation time to provide stall protection.

[0022] 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 apparent to those skilled in the art. Therefore, the scope of the present invention should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

[0023] The above descriptions are merely preferred embodiments of the present invention. All equivalent changes and modifications made within the scope of the present invention should fall within the scope of the present invention.

Claims

1. A motor controller, characterized in that: Include: a switching circuit coupled to a motor for driving the motor; a control unit for generating a control signal to control the switch circuit, wherein the motor controller determines a non-excitation time, and when the motor is in a stalled state, the motor controller sets the non-excitation time to a variable value; a stall protection unit coupled to the control unit and configured to generate a driving signal to the control unit, wherein the driving signal has the non-excitation time; a rotor detection unit, the rotor detection unit generating a first detection signal to the stall protection unit; a non-excitation time modulation unit, the non-excitation time modulation unit generating a timing signal to the stall protection unit; and A counting unit generates a counting signal to the non-excitation time modulation unit.

2. The motor controller according to claim 1, wherein: The motor controller utilizes the non-excitation time to achieve a stall protection function.

3. The motor controller according to claim 1, wherein: The motor controller determines whether the motor is in the stalled state by detecting a rotor speed.

4. The motor controller according to claim 1, wherein: The motor controller determines whether the motor is in the stalled state by detecting a rotor temperature.

5. The motor controller according to claim 1, wherein: When the motor controller successfully starts the motor, the counting unit is reset.

6. The motor controller according to claim 1, wherein: The motor controller further has an input voltage detection unit. The input voltage detection unit generates a second detection signal to the non-excitation time modulation unit.

7. The motor controller according to claim 1, wherein: The motor controller further has a temperature detection unit. The temperature detection unit generates a third detection signal to the non-excitation time modulation unit.

8. The motor controller according to claim 1, wherein: The motor controller also has an excitation time. When the motor is in the stalled state, the motor controller sets the excitation time to a fixed value.

9. The motor controller according to claim 1, wherein: The motor controller changes the non-excitation time with a certain number of times.

10. The motor controller according to claim 9, wherein: The greater the number, the longer the non-excitation time.

11. The motor controller according to claim 1, wherein: The motor controller changes the non-excitation time according to an input voltage.

12. The motor controller according to claim 11, wherein: The input voltage is a power supply voltage.

13. The motor controller according to claim 11, wherein: When the input voltage is larger, the non-excitation time is longer.

14. The motor controller according to claim 1, wherein: The motor controller changes the non-excitation time with a temperature.

15. The motor controller according to claim 14, wherein: The higher the temperature, the longer the non-excitation time.

16. The motor controller according to claim 1, wherein: The motor is a three-phase motor.

17. The motor controller according to claim 1, wherein: The motor controller is applied to a sensorless motor.

18. The motor controller according to claim 1, wherein: The motor controller increases a restart count within a limited time.

19. The motor controller according to claim 1, wherein: The motor controller is used to improve a startup success rate.

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