TWI735290B - Overvoltage protection circuit - Google Patents

Abstract

An overvoltage protection circuit can be applied to a motor controller. The overvoltage protection circuit comprises a voltage controller, a comparator, and a switching circuit so as to prevent damage to a driving circuit. The driving circuit is configured to supply a driving current to a motor coil.

Description

Overvoltage protection circuit

The present invention relates to an over-voltage protection circuit, in particular to an over-voltage protection circuit that can be applied to a motor controller.

Figure 1 is a schematic diagram of a conventional motor controller 10. The motor controller 10 is used to drive a motor, wherein the motor has a motor coil L. The motor controller 10 has a driving circuit 100 and a controller 110. The driving circuit 100 has a transistor 101, a transistor 102, a transistor 103, and a transistor 104. When the motor is driving forward, it can be set that the transistor 101 and the transistor 104 are conductive and the transistor 102 and the transistor 103 are not conductive. At this time, the current of the motor coil L flows from the terminal Vm to the transistor 101, the first The terminal O1, the second terminal O2, the transistor 104, and finally flow to the terminal GND. When the motor needs to decelerate or turn, it is set that the transistor 102 and the transistor 103 are conductive and the transistor 101 and the transistor 104 are not conductive, so as to reduce the current of the motor coil L or reverse the direction of the current of the motor coil L. At this time, the current of the motor coil L will maintain the original direction due to the inductance effect or inertial motion, that is, the current of the motor coil L flows from the terminal GND to the transistor 102, the first terminal O1, and the second terminal O2 in sequence. , Transistor 103, finally flows to the terminal Vm, causing the voltage of the terminal Vm to rise. If the voltage of the terminal Vm is greater than the withstand voltage of the driving circuit 100 and the controller 110, the driving circuit 100 and the controller 110 may be damaged.

In view of the foregoing problems, the object of the present invention is to provide an overvoltage protection circuit to protect the driving circuit.

According to the present invention, the overvoltage protection circuit is provided. The overvoltage protection circuit has a voltage controller, a comparator, and a switching circuit to avoid damage to the driving circuit. The driving circuit is used to supply a driving current to a motor coil.

10, 20: Motor controller

100, 200: drive circuit

110: Controller

210: The first control unit

220: The first overvoltage protection circuit

230: second control unit

240: second overvoltage protection circuit

Vm, GND: terminal

101,102,103,104,201,202,203,204,224,225: Transistor

L: Motor coil

O1: first endpoint

O2: second endpoint

Io: output current

221: Voltage Controller

CS1: First current source

CS2: second current source

222: Comparator

Vi: input voltage

Vc: control signal

223: switching circuit

V1: The first signal

V2: second signal

Vd: detection signal

Figure 1 is a schematic diagram of a conventional motor controller.

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

Figure 3 is a schematic diagram of a first overvoltage protection circuit according to an embodiment of the present invention.

The following description will make the purpose, features, and advantages of the present invention more obvious. The preferred embodiments according to the present invention will be described in detail with reference to the drawings.

Figure 2 is a schematic diagram of the motor controller 20 of the present invention. The motor controller 20 is used to drive a motor, wherein the motor has a motor coil L. The motor controller 20 has a driving circuit 200, a first control unit 210, a first overvoltage protection circuit 220, a second control unit 230, and a second overvoltage protection circuit 240.

The driving circuit 200 has a transistor 201, a transistor 202, a transistor 203, and a transistor 204 for supplying a driving current to the motor coil L, wherein a supply voltage is used for providing the voltage of the driving circuit 200. The motor coil L has a first end O1 and a second end O2. The transistor 201 is coupled to a first terminal O1 and a terminal Vm. The transistor 202 is coupled to a first terminal O1 and a terminal GND. Transistor 203 Coupled to the second terminal O2 and the terminal Vm. The transistor 204 is coupled to the second terminal O2 and the terminal GND. Transistor 201, transistor 202, transistor 203, and transistor 204 can be a P-type metal oxide semi-transistor or an N-type metal oxide semi-transistor. In Figure 2, the transistor 201 and the transistor 203 take two P-type metal oxide semi-transistors as an example, and the transistor 202 and the transistor 204 take two N-type metal oxide semi-transistors as an example.

The first control unit 210 is used to control the conduction of the transistor 201 and the transistor 202, and the second control unit 230 is used to control the conduction of the transistor 203 and the transistor 204. The first overvoltage protection circuit 220 is coupled to the first terminal O1 to prevent the voltage of the terminal Vm from being excessively high, so as to protect the driving circuit 200. Similarly, the second overvoltage protection circuit 240 is coupled to the second terminal O2 to prevent the voltage of the terminal Vm from being excessively high, so as to protect the driving circuit 200. Specifically, when the second control unit 230 switches the transistor 204 from conducting to non-conducting, if it detects that the voltage of the second terminal O2 is greater than the supply voltage, it will turn on the transistor 204 to enable The current flowing to the terminal Vm is directed to the terminal GND by the transistor 204. When the current no longer flows to the terminal Vm, the driving circuit 200 will not be damaged due to the excessive voltage of the terminal Vm.

0.4伏特且第二參考電壓

0.4伏特。切換 電路223接收第一信號V1、控制信號Vc、以及一偵測信號Vd，用以產生一第二信號V2至電晶體202。 FIG. 3 is a schematic diagram of the first overvoltage protection circuit 220 of the present invention. The first overvoltage protection circuit 220 has a voltage controller 221, a comparator 222, and a switching circuit 223. The voltage controller 221 has a transistor 224, a transistor 225, a first current source CS1, and a second current source CS2, wherein the transistor 224 and the transistor 225 are each a P-type metal oxide semi-transistor. The transistor 224 is coupled to the first terminal O1, the transistor 201, the transistor 202, and the first current source CS1 for generating a first signal V1 to the switching circuit 223. The transistor 225 is coupled to a voltage source, a second current source CS2, and the transistor 224. Among them, the size of the transistor 224 is the same as the size of the transistor 225. The comparator 222 compares the voltage of the first terminal O1 with an input voltage Vi to generate a control signal Vc to the switching circuit 223. According to different detection times, the input voltage Vi can be set to the supply voltage, the supply voltage plus a first reference voltage, or the supply voltage minus a second reference voltage, where the first reference voltage

0.4 volts and second reference voltage

0.4 volts. The switching circuit 223 receives the first signal V1, the control signal Vc, and a detection signal Vd to generate a second signal V2 to the transistor 202.

Specifically, when the output current Io flowing from the motor coil L to the first terminal O1 is greater than 0 and the voltage of the first terminal O1 is greater than the supply voltage, the control signal Vc is at a high potential H, so that the second signal V2 It is coupled to the first signal V1 to control the transistor 202. When the voltage of the first terminal O1 rises, the voltages of the first signal V1 and the second signal V2 will rise, thereby slightly turning on the transistor 202 and operating the transistor 202 in a saturation region to enter an overvoltage protection mechanism . At this time, the output current Io is directed to the terminal GND via the transistor 202, so that the voltage of the first terminal O1 drops, so as to prevent the driving circuit 200 from being damaged. When the voltage of the second signal V2 is less than a third reference voltage or the output current Io is less than a reference current, the detection signal Vd is at a high potential H at this time, so that the second signal V2 is at a low potential L, thereby turning the transistor 202 Do not conduct to exit the overvoltage protection mechanism. In addition, the structure of the second overvoltage protection circuit 240 is similar to the structure of the first overvoltage protection circuit 220, and will not be repeated here.

The overvoltage protection circuit of the present invention can be applied to single-phase or multi-phase motors. In addition, the present invention can be applied to inductive actuators, such as brushless motors, DC motors, voice coil motors, or electromagnetic actuators. Since the overvoltage protection circuit of the present invention does not need to use an operational amplifier and a frequency compensation circuit, the difficulty and complexity of circuit design can be greatly reduced, and the manufacturing cost of the motor controller can be reduced.

Although the present invention has been described with the preferred embodiment as an example, it should be understood that the present invention is not limited to the disclosed embodiment. On the contrary, the present invention is intended to cover various modifications and similar configurations that are obvious to those familiar with the art. Therefore, the scope of the patent application should be based on the broadest interpretation to include all such modifications and similar configurations.

The foregoing descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the present invention.

20: Motor controller

200: drive circuit

210: The first control unit

220: The first overvoltage protection circuit

230: second control unit

240: second overvoltage protection circuit

Vm, GND: terminal

201, 202, 203, 204: Transistor

L: Motor coil

O1: first endpoint

O2: second endpoint

Claims (19)

An overvoltage protection circuit is used to protect a drive circuit. The drive circuit is used to supply a drive current to a motor coil and the motor coil has a first end and a second end. The overvoltage protection circuit includes: A voltage controller coupled to the first terminal, wherein the voltage controller includes a first transistor and a first current source, and the first current source is coupled to the first transistor for generating a first transistor Signal; a comparator for generating a control signal according to the voltage of the first terminal; and a switching circuit for receiving the first signal and the control signal for generating a second signal to the driving circuit, wherein The control signal is used to determine whether to couple the second signal to the first signal. The overvoltage protection circuit described in the first item of the scope of patent application, wherein the comparator is used to compare the voltage of the first terminal with an input voltage. According to the overvoltage protection circuit described in item 2 of the scope of patent application, the driving circuit includes: a second transistor coupled to the first terminal and a third terminal; and a third transistor coupled to To the first terminal and a fourth terminal, one of the supply voltages is used to provide the voltage of the driving circuit. The overvoltage protection circuit described in item 3 of the scope of patent application, wherein the driving circuit further comprises: a fourth transistor coupled to the second terminal and the third terminal; and a fifth transistor, Coupled to the second end and the fourth end. In the overvoltage protection circuit described in item 4 of the scope of patent application, the second transistor and the fourth transistor are respectively a P-type metal oxide semi-transistor. In the overvoltage protection circuit described in item 5 of the scope of patent application, the third transistor and the fifth transistor are respectively an N-type metal oxide semi-transistor. The overvoltage protection circuit described in item 3 of the scope of patent application, wherein the input voltage is the supply voltage. In the overvoltage protection circuit described in item 3 of the scope of patent application, the input voltage is the supply voltage plus a first reference voltage. The overvoltage protection circuit described in item 8 of the scope of patent application, wherein the first reference voltage

0.4 volts. For the overvoltage protection circuit described in item 3 of the scope of patent application, the input voltage is the supply voltage minus a second reference voltage. The overvoltage protection circuit described in item 10 of the scope of patent application, wherein the second reference voltage

0.4 volts. The overvoltage protection circuit described in item 3 of the scope of patent application, wherein the second signal is used to control the third transistor. The overvoltage protection circuit described in item 12 of the scope of patent application, wherein when an overvoltage protection mechanism is entered, the third transistor is turned on. The overvoltage protection circuit described in item 13 of the scope of patent application, wherein the third electrocrystalline system operates in a saturation region. The overvoltage protection circuit described in item 14 of the scope of patent application, wherein when the voltage of the second signal is less than a third reference voltage, the third transistor is made non-conducting to exit the overvoltage protection mechanism. The overvoltage protection circuit described in item 14 of the scope of patent application, wherein when the output current flowing from the motor coil to the first terminal is less than a reference current, the third transistor is made non-conducting to exit the overvoltage protection mechanism. The overvoltage protection circuit described in item 1 of the scope of patent application, wherein the overvoltage protection circuit is applied to a single-phase motor or a multi-phase motor. The overvoltage protection circuit described in claim 18, wherein the voltage controller further includes: a sixth transistor coupled to the first transistor; and a second current source coupled to the sixth transistor Transistor. The overvoltage protection circuit described in claim 18, wherein the first transistor is coupled to the first terminal and the sixth transistor is coupled to a voltage source.

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