motor unit

Abstract

A motor unit and a motor controller are disclosed. The motor unit has a power supply, a diode, a capacitor, and a motor controller. The motor controller has a switching circuit and a control unit. The switching circuit has a first upper switch, a first lower switch, a second upper switch, and a second lower switch. The control unit is configured to turn on the first upper switch and the second lower switch and not to turn on the first lower switch and the second upper switch. The control unit is configured to not to turn on the first upper switch and the second lower switch when an input voltage is less than a first reference voltage. The motor controller can be used to avoid an overvoltage problem.

Description

TECHNICAL FIELD

[0001] The present invention relates to a motor unit, and in particular, to a motor unit capable of avoiding overvoltage problem. BACKGROUND

[0002] Figure 1 Fig. 1 is a schematic diagram of a prior art motor unit 10. The motor unit 10 has a power supply 130, a diode D, a capacitor C and a motor controller 100. The motor controller 100 is used to drive a motor having a motor coil L. The motor coil L has a first end point Ol and a second end point 02. The motor controller 100 has a switching circuit 110 and a control unit 120. The switching circuit 110 has a transistor 101, a transistor 102, a transistor 103 and a transistor 104 for supplying a coil current IL to the motor coil L. The control unit 120 generates a first control signal Cl, a second control signal C2, a third control signal C3 and a fourth control signal C4 for controlling the conduction of the transistors 101, 102, 103 and 104 respectively.

[0003] The power supply 130 provides an input voltage VIN to the motor controller 100 via the diode D. When the power supply 130 stops supplying power and the input voltage VIN is less than a certain voltage, the motor controller 100 will turn off the switching circuit 110. At this time, the motor coil L still has a residual current which will charge the capacitor C via a body diode of an upper transistor to cause an overvoltage problem. SUMMARY

[0004] In view of the foregoing, the present invention aims to provide a motor unit capable of avoiding overvoltage problem.

[0005] A motor unit is provided according to the present application. The motor unit has a power supply, a diode, a capacitor and a motor controller. The diode is coupled to the power supply, wherein the power supply provides an input voltage to the motor controller via the diode. The capacitor is coupled to the diode. The motor controller is used to drive a motor, wherein the motor has a motor coil. The motor controller has a switching circuit and a control unit. The switching circuit is used to supply a coil current to the motor coil, wherein the switching circuit has a first upper switch, a first lower switch, a second upper switch and a second lower switch. The control unit generates control signals to control the switching circuit, wherein the control unit is used to turn on the first upper switch and the second lower switch and turn off the first lower switch and the second upper switch. When the input voltage is less than a first reference voltage, the control unit is used to turn off the first upper switch, the first lower switch, the second upper switch and the second lower switch. At this time, current flows sequentially to the first lower switch, the motor coil and the second upper switch, so that residual current charges the capacitor and the input voltage starts to increase. The first reference voltage can be a low voltage lock voltage. When the input voltage is greater than the first reference voltage again, the control unit is used to turn on the first upper switch and the second lower switch and turn off the first lower switch and the second upper switch. Therefore, the motor controller can have enough time to discharge the residual current. The motor controller makes the input voltage oscillate around the first reference voltage.

[0006] When the input voltage is less than a second reference voltage, the control unit is used to turn off the first upper switch, the first lower switch, the second upper switch and the second lower switch. The second reference voltage can be a power-on reset voltage and the first reference voltage is greater than the second reference voltage. The motor controller can be disposed on an integrated circuit chip. When the input voltage is less than the second reference voltage, the integrated circuit chip can be reset. In addition, when the input voltage is less than the second reference voltage, the motor controller can reset a memory unit. According to an embodiment of the present application, when the input voltage is less than the second reference voltage, the motor controller does not make the motor have a braking jerk. The motor unit and the motor controller can be applied to a single-phase motor or a multi-phase motor. The motor controller can be used to avoid an overvoltage problem. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 A schematic diagram of an existing motor unit.

[0008] Figure 2 A schematic diagram of a motor unit according to an embodiment of the present application.

[0009] Figure 3 A timing diagram according to an embodiment of the present application.

[0010] Explanation of reference numerals in the attached diagram: 10-Motor unit; 100-Motor controller; 110-Switching circuit; 130-Power supply; 101, 102, 103, 104-Transistors; 120-Control unit; 20-Motor unit; 200-Motor controller; 210-Switching circuit; 201-First transistor; 202-Second transistor; 203-Third transistor; 204-Fourth transistor; L-Motor coil; IL-Coil current; 220-Control unit; O1-First terminal; O2-Second terminal; C1-First control signal; C2-Second control signal; C3-Third control signal; C4-Fourth control signal; VIN-Input voltage; C-Capacitor; D-Diode; 250-Power supply; VP-Power supply voltage; 230-First comparator; 240-Second comparator; Vr1-First reference voltage; Vr2-Second reference voltage; D1-First drive signal; D2-Second drive signal; IN-Input terminal; GND-Third terminal. 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 2 This is a schematic diagram of a motor unit 20 according to an embodiment of the present invention. The motor unit 20 includes a power supply 250, a diode D, a capacitor C, and a motor controller 200. The motor controller 200 drives a motor, wherein the motor has a motor coil L. The motor coil L has a first terminal O1 and a second terminal O2. The motor controller 200 includes a switching circuit 210, a control unit 220, a first comparator 230, and a second comparator 240. The switching circuit 210 includes a first transistor 201, a second transistor 202, a third transistor 203, and a fourth transistor 204 for supplying a coil current IL to the motor coil L. The first transistor 201 is coupled to an input terminal IN and the first terminal O1, while the second transistor 202 is coupled to the first terminal O1 and a third terminal GND. The third transistor 203 is coupled to the input terminal IN and the second terminal O2, while the fourth transistor 204 is coupled to the second terminal O2 and the third terminal GND. The first transistor 201, the second transistor 202, the third transistor 203, and the fourth transistor 204 can be either a P-type metal-oxide-semiconductor (MOSFET) or an N-type MOSFET. For example... Figure 2As shown, the first transistor 201 and the third transistor 203 are exemplified as two P-type MOS transistors. The second transistor 202 and the fourth transistor 204 are exemplified as two N-type MOS transistors. In addition, the switching circuit 210 is a H-bridge circuit. The first transistor 201 can be a first upper side switch. The second transistor 202 can be a first lower side switch. The third transistor 203 can be a second upper side switch. The fourth transistor 204 can be a second lower side switch.

[0013] The control unit 220 generates a first control signal C1, a second control signal C2, a third control signal C3 and a fourth control signal C4 for controlling the conduction of the first transistor 201, the second transistor 202, the third transistor 203 and the fourth transistor 204, respectively. The power supply 250 is coupled to one end of the diode D and generates a power voltage VP to the diode D. The other end of the diode D is coupled to one end of the capacitor C and the input terminal IN. The diode D can be used to prevent the reverse current generated by the motor controller 200 from flowing back to the power supply 250. The other end of the capacitor C is coupled to the third terminal GND. The power supply 250 provides an input voltage VIN to the motor controller 200 via the diode D, so that the motor controller 200 can operate normally. The first comparator 230 compares the input voltage VIN with a first reference voltage Vr1 to generate a first drive signal D1 to the control unit 220. The second comparator 240 compares the input voltage VIN with a second reference voltage Vr2 to generate a second drive signal D2 to the control unit 220, wherein the first reference voltage Vr1 is greater than the second reference voltage Vr2.

[0014] Figure 3FIG. 4 is a timing diagram of an embodiment of the present application. The control unit 220 controls the first control signal C1, the second control signal C2, the third control signal C3, and the fourth control signal C4 to turn on the first transistor 201 and the fourth transistor 204 and to turn off the second transistor 202 and the third transistor 203. At this time, the current flows from the input terminal IN to the first transistor 201, the motor coil L, and the fourth transistor 204 in sequence to deliver energy to the motor. When the power supply 250 stops supplying power, the power supply voltage VP immediately decreases to 0 and causes the input voltage VIN to start decreasing. When the input voltage VIN is less than the first reference voltage Vr1, the first comparator 230 causes the first drive signal D1 to be at a low level. The control unit 220 controls the first control signal C1, the second control signal C2, the third control signal C3, and the fourth control signal C4 to turn off the first transistor 201, the second transistor 202, the third transistor 203, and the fourth transistor 204. At this time, the current flows to the second transistor 202, the motor coil L, and the third transistor 203 in sequence to cause the residual current to charge the capacitor C and to cause the input voltage VIN to start increasing. When the input voltage VIN is greater than the first reference voltage Vr1 again, the first comparator 230 causes the first drive signal D1 to be at a high level. The control unit 220 controls the first control signal C1, the second control signal C2, the third control signal C3, and the fourth control signal C4 to turn on the first transistor 201 and the fourth transistor 204 and to turn off the second transistor 202 and the third transistor 203. Thus, according to an embodiment of the present application, the motor controller 200 can have sufficient time to discharge the residual current. As shown in FIG. 4, the motor controller 200 causes the input voltage VIN to oscillate around the first reference voltage Vr1. For example, the first reference voltage Vr1 can be an undervoltage lockout voltage, and the motor controller 200 can be disposed on an integrated circuit chip. Figure 3

[0015] ​When the input voltage VIN is less than the second reference voltage Vr2, the second comparator 240 causes the second driving signal D2 to be at the low level, where the second reference voltage Vr2 can be a power on reset voltage. The control unit 220 controls the first control signal C1, the second control signal C2, the third control signal C3, and the fourth control signal C4 to turn off the first transistor 201, the second transistor 202, the third transistor 203, and the fourth transistor 204. At this time, the residual current of the motor coil L has been discharged, so the integrated circuit chip can be reset, and there is no overvoltage problem. That is, the motor controller 200 can reset a memory unit. According to an embodiment of the present application, when the input voltage VIN is less than the second reference voltage Vr2, the motor controller 200 does not cause the motor to have a jerky feeling of braking. The motor unit 20 and the motor controller 200 can be applied to a single-phase motor or a multi-phase motor. The motor controller 200 can be used to avoid an overvoltage problem.

[0016] While the application has been described by way of example with reference to preferred embodiments, it is to be understood that the application is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the application. The application based on this application is to be limited only by the scope of the appended claims.

[0017] The above descriptions are only the preferred embodiments of the present application, and all equivalent changes and modifications made according to the patent application scope of the present application should be included in the scope of the present application.

Claims

1. A motor unit characterized by comprising: Comprising: a power supply; a motor controller comprising a switching circuit and a control unit, wherein the switching circuit has a first upper switch, a first lower switch, a second upper switch and a second lower switch; a diode coupled to the power supply, wherein the power supply provides an input voltage to the motor controller via the diode; and a capacitor coupled to the diode, wherein the control unit is configured to turn on the first upper switch and the second lower switch and not to turn on the first lower switch and the second upper switch, and when the input voltage is less than a first reference voltage, the control unit is configured to not to turn on the first upper switch and the second lower switch, and when the input voltage is less than a second reference voltage, the control unit is configured to not to turn on the first upper switch, the first lower switch, the second upper switch and the second lower switch.

2. The motor unit of claim 1, wherein, When the input voltage is less than the first reference voltage, the control unit is further configured to not to turn on the first lower switch and the second upper switch.

3. The motor unit of claim 1, wherein, The first reference voltage is a low voltage lockout voltage.

4. The motor unit of claim 1, wherein, When the input voltage is greater than the first reference voltage again, the control unit is configured to turn on the first upper switch and the second lower switch and not to turn on the first lower switch and the second upper switch.

5. The motor unit of claim 1, wherein, The motor controller causes the input voltage to oscillate around the first reference voltage.

6. The motor unit of claim 1, wherein, The second reference voltage is a power-on reset voltage.

7. The motor unit of claim 1, wherein, The first reference voltage is greater than the second reference voltage.

8. The motor unit of claim 1, wherein, When the input voltage is less than the second reference voltage, the motor controller resets a memory unit.

9. The motor unit of claim 1, wherein, The motor controller is disposed on an integrated circuit chip, and resets the integrated circuit chip when the input voltage is less than the second reference voltage.

10. The motor unit of claim 1, wherein, The motor unit is applied to a single-phase motor or a multi-phase motor.

11. The motor unit of claim 1, wherein, The motor controller is configured to avoid an overvoltage problem.

12. A motor controller for driving a motor having a motor coil, characterized in that, The motor controller comprises: a switching circuit configured to supply a coil current to a motor coil, wherein the switching circuit has a first upper switch, a first lower switch, a second upper switch and a second lower switch; and a control unit configured to generate a plurality of control signals to control the switching circuit, wherein the control unit is configured to turn on the first upper switch and the second lower switch and not to turn on the first lower switch and the second upper switch, and when an input voltage is less than a first reference voltage, the control unit is configured to not to turn on the first upper switch and the second lower switch, and when the input voltage is less than a second reference voltage, the control unit is configured to not to turn on the first upper switch, the first lower switch, the second upper switch and the second lower switch.

13. The motor controller of claim 12, wherein, When the input voltage is less than the first reference voltage, the control unit is further configured to not to turn on the first lower switch and the second upper switch.

14. The motor controller of claim 12, wherein, The first reference voltage is a low voltage lockout voltage.

15. The motor controller of claim 12, wherein, When the input voltage is greater than the first reference voltage again, the control unit is configured to turn on the first upper switch and the second lower switch and not to turn on the first lower switch and the second upper switch.

16. The motor controller of claim 12, wherein, The motor controller causes the input voltage to oscillate around the first reference voltage.

17. The motor controller of claim 12, wherein, The second reference voltage is a power-on reset voltage.

18. The motor controller of claim 12, wherein, The first reference voltage is greater than the second reference voltage.

19. The motor controller of claim 12, wherein, The motor controller resets a memory unit when the input voltage is less than the second reference voltage.

20. The motor controller of claim 12, wherein, The motor controller is disposed on an integrated circuit chip, and resets the integrated circuit chip when the input voltage is less than the second reference voltage.

21. The motor controller of claim 12, wherein, The motor controller is applied to a single-phase motor or a multi-phase motor.

22. The motor controller of claim 12, wherein, The motor controller is used to avoid an overvoltage problem.

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