Digital output circuit and motor controller
By introducing optocouplers and switch tubes into the digital output circuit, combining the design of detection unit and voltage embedding unit, overcurrent protection of the digital output circuit is achieved, and circuit damage caused by overcurrent in the prior art is solved, reducing the problem of overcurrent in the prior art. Cost and simplify circuit design.
Patent Information
- Application Number
- CN202323588748.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-27
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2033-12-27
AI Technical Summary
Existing digital output circuits are prone to excessive current when the current limiting resistance is too small or the external power supply voltage is too high, resulting in circuit damage. Existing overcurrent protection methods such as recovering the heat generation delay of the fuse or requiring additional power wiring, which increases complexity and cost.
Design a digital output circuit including an optocoupler, a switch tube and an overcurrent protection unit, connects the overcurrent protection unit in series at the digital output port through a first resistor, and clamps the current to a preset using a detection unit and a voltage embedding unit. value to prevent overcurrent.
No additional power supply is required, the circuit is simple and low-cost, effectively preventing the digital output circuit from being damaged due to short circuit or overcurrent, improving the reliability and life of the circuit.
Smart Images
Figure CN222234837U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of electronic equipment, and more specifically, to a digital output circuit and a motor controller. Background Art
[0002] In industrial control equipment, the digital output circuit (Digital Output Circle, referred to as DO circuit) is the most widely used circuit. For example, it can be used for frequency converters or motor drivers to transmit high and low level status information and pulse information to the host computer (such as PLC, programmable logic controller). The DO circuit will be connected to the digital input circuit (Digital Input Circle, referred to as DI circuit) of the host computer, such as Figure 1 However, during use, if the current limiting resistor is too small or the external power supply voltage is too high, excessive current will flow between the DO of the digital output circuit and the reference ground, thereby damaging the digital output circuit.
[0003] In the related art, an overcurrent protection component is added to the digital output circuit to avoid the risk of failure of the digital output circuit due to excessive current. Currently, a resettable fuse is usually connected in series with the output terminal DO or the reference ground terminal to achieve overcurrent protection, or an external 24V power supply is connected to the digital output circuit to build an overcurrent protection unit circuit using the power supply.
[0004] However, since the resettable fuse is disconnected due to overcurrent and heat generation, the delay time during the disconnection process can be as short as tens of milliseconds or as long as several seconds. When the overcurrent phenomenon is eliminated, the time for the resettable fuse to return to normal is also very long. This method will inevitably greatly reduce the life of the DO circuit and the resettable fuse, and eventually cause the digital output circuit to fail. The method of building an overcurrent protection unit circuit by connecting an external 24V power supply requires additional external power supply wiring, which increases wiring complexity and cost. Utility Model Content
[0005] The utility model provides a digital output circuit, comprising an optocoupler, a first switch tube and a digital output port, wherein the emitter of the optocoupler output end is connected to the control end of the first switch tube, and the collector serves as the digital output port. The utility model is characterized in that it also comprises a first resistor and an overcurrent protection unit, wherein the first resistor is connected in series at the digital output port, and the overcurrent protection unit comprises a first input end, a second input end and a first output end, wherein the first input end and the second input end are respectively connected to the two ends of the first resistor, and the first output end is connected to the control end of the first switch tube.
[0006] Optionally, a second resistor is further connected between the first resistor and the collector of the optocoupler output end.
[0007] Optionally, the first switch tube is an NPN transistor.
[0008] Optionally, the control end of the first switch tube is connected to its emitter via a third resistor and connected to a reference ground, the emitter of the first switch tube is connected to the second output end of the overcurrent protection unit, and the collector is connected to the digital output port.
[0009] Optionally, the overcurrent protection unit includes a detection unit and a voltage clamping unit, the first input terminal and the second input terminal of the detection unit are respectively connected to the two ends of the first resistor, and the output terminal is connected to the control end of the voltage clamping unit, and the voltage clamping unit clamps the voltage across the first resistor to a preset value according to the control signal output by the detection unit.
[0010] Optionally, the detection unit includes a second switch tube, and the voltage clamping unit includes a third switch tube.
[0011] Optionally, the voltage clamping unit further includes a fourth resistor and a fifth resistor connected in series with the fourth resistor, and the control end of the third switch tube is connected between the fourth resistor and the fifth resistor.
[0012] Optionally, the second switch tube is a PNP transistor, the control end and the emitter of the second switch tube are respectively connected to the two ends of the first resistor, and the collector is connected to the control end of the third switch tube via the fourth resistor.
[0013] Optionally, the third switch tube is an NPN transistor, the control end of the third switch tube is connected to its emitter via the fifth resistor and is connected to a reference ground, and the collector is connected to the control end of the first switch tube.
[0014] The utility model also provides a motor driver, comprising the digital output circuit as described above.
[0015] The digital output circuit and motor controller of the utility model perform overcurrent protection on the output port of the digital output circuit through an overcurrent protection unit, and do not require an additional power supply. The circuit is simple and the cost is low. While not affecting the function of the digital output circuit, the digital output circuit can be effectively prevented from being damaged by short circuit and overcurrent. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 A schematic diagram of a conventional digital output circuit and a digital input circuit;
[0017] Figure 2 A schematic diagram of a digital output circuit provided by an embodiment of the utility model;
[0018] Figure 3A schematic diagram of an overcurrent protection unit provided in an embodiment of the utility model;
[0019] Figure 4 A schematic diagram of a first embodiment of an overcurrent protection unit provided in an embodiment of the utility model;
[0020] Figure 5 Another schematic diagram of a digital output circuit provided by an embodiment of the utility model.
[0021] Description of reference numerals:
[0022] 1-overcurrent protection unit, 11-first input end, 12-second input end, 13-first output end, 14-second output end, 101-detection unit, 102-voltage clamping unit, R1-first resistor, R2-second resistor, R3-third resistor, R4-fourth resistor, R5-fifth resistor, U1-optical coupler, Q1-first switch tube, Q2-second switch tube, Q3-third switch tube, DO-digital output port. DETAILED DESCRIPTION
[0023] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.
[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.
[0025] The utility model provides a digital output circuit to solve the problems in the related art. Figure 2As shown, it is a schematic diagram of the digital output circuit of the utility model, which can be applied to motor controllers, etc., and can transmit high and low level state information and pulse information to the upper computer (such as PLC, i.e., programmable logic controller). The digital output circuit in this embodiment includes: an optocoupler U1, a first switch tube Q1, a digital output port DO, a first resistor R1 and an overcurrent protection unit 1, the emitter of the optocoupler output end is connected to the control end of the first switch tube Q1, the collector is used as the digital output port DO, the first resistor R1 is connected in series at the digital output port DO, and the overcurrent protection unit 1 includes a first input end 11, a second input end 12 and a first output end 13, the first input end and the second input end are respectively connected to the two ends of the first resistor R1, and the first output end 13 is connected to the control end of the first switch tube Q1. A second resistor R2 is also connected between the first resistor R1 and the collector of the optocoupler output end. In one example of this embodiment, the transistor at the output end of the optocoupler U1 is an NPN transistor, and the first switch tube Q1 is an NPN transistor.
[0026] It should be understood that the transistor at the output end of the optocoupler U1 and the first switch tube Q1 of the utility model are not limited to NPN transistors, but can also be other types of switch tubes, such as PNP transistors, which can be flexibly selected according to actual application requirements.
[0027] The control end of the first switch tube Q1 is connected to the emitter of Q1 via the third resistor R3 and connected to the reference ground. The emitter of the first switch tube Q1 is connected to the second output end 14 of the overcurrent protection unit 1, and the collector of the first switch tube Q1 is connected to the digital output port.
[0028] In this embodiment, Figure 3 As shown, it is a schematic diagram of the overcurrent protection unit of this embodiment. The overcurrent protection unit 1 may include a detection unit 101 and a voltage clamping unit 102. The first input terminal and the second input terminal of the detection unit are respectively connected to the two ends of the first resistor R1, and the output terminal is connected to the control terminal of the voltage clamping unit. The voltage clamping unit clamps the voltage across the first resistor to a preset value according to the control signal output by the detection unit. The first input terminal of the detection unit is the first input terminal 11 of the overcurrent protection unit, and the second input terminal of the detection unit is the second input terminal 12 of the overcurrent protection unit. The overcurrent protection unit 1 includes four external ports, namely the first input terminal 11, the second input terminal 12, the first output terminal 13, and the second output terminal 14.
[0029] Specifically, in one example of this embodiment, Figure 4As shown, it is a schematic diagram of a first embodiment of an overcurrent protection unit, the detection unit includes a second switch tube Q2, and the voltage clamping unit includes a third switch tube Q3. Specifically, the voltage clamping unit also includes a fourth resistor R4 and a fifth resistor R5 connected in series with the fourth resistor R4. The control end of the third switch tube Q3 is connected between the fourth resistor R4 and the fifth resistor R5. In an example of this embodiment, the second switch tube Q2 is a PNP transistor, the control end and the emitter of the second switch tube are respectively connected to the two ends of the first resistor R1, and the collector is connected to the control end of the third switch tube Q3 via the fourth resistor R4. The third switch tube Q3 is an NPN transistor, and the control end of the third switch tube is connected to the emitter of Q3 via the fifth resistor R5 and is connected to the reference ground, and the collector is connected to the control end of the first switch tube Q1.
[0030] Combination Figure 5 FIG. 1 is a schematic diagram of a digital output circuit of this embodiment. The principle of overcurrent protection of the digital output circuit of this embodiment is as follows:
[0031] When the input terminal Input of the digital output circuit is at a low level, the output transistor of the optocoupler U1 will not be turned on, so the voltage between the base and the emitter of the first switch tube Q1 is 0V, and the emitter and the collector of the first switch tube Q1 will not be turned on. The digital output port DO of the digital output circuit is at a high level. At this time, there is no current on the first resistor R1, and the voltage difference between its two ends is 0V, that is, the voltage between the base and the emitter of the second switch tube Q2 is 0V, so the emitter and the collector of the second switch tube Q2 will not be turned on, and the overcurrent unit will not operate.
[0032] When the input terminal Input of the digital output circuit is at a high level, the output transistor of the optocoupler U1 is turned on, the voltage between the base and the emitter of the first switch tube Q1 is greater than its PN junction conduction voltage, the emitter and the collector of the first switch tube Q1 are turned on, and the digital output port DO is at a low level; at this time, current flows through the first resistor R1 and generates a voltage difference, but as long as it is less than the PN junction conduction voltage between the emitter and the base of the second switch tube Q2, the emitter and the collector of the second switch tube Q2 will not be turned on, and the overcurrent unit will not operate.
[0033] When the input terminal Input of the digital output circuit is at a high level, and an overcurrent is generated between the digital output port DO and the reference ground, the current will generate a large voltage difference across the first resistor R1. When the voltage difference is greater than the PN junction conduction voltage between the emitter and base of the second switch tube Q2, the emitter and collector of the second switch tube Q2 will be turned on, and the voltage at the digital output port DO will pass through the emitter and collector of the second switch tube Q2, and after being divided by the fourth resistor R4 and the fifth resistor R5, it will be applied to the third switch tube Q3. When the voltage of the base is greater than the PN junction conduction voltage of the base and emitter of the third switch tube Q3, the emitter and collector of the third switch tube Q3 will be turned on, and the base and emitter voltage of the first switch tube Q1 will be pulled to a low level, which is less than the PN junction conduction voltage of the base and emitter of Q1, so that the emitter and collector of the first switch tube Q1 will be cut off, and the overcurrent between the digital output port DO and the reference ground will be cut off. At this time, the voltage difference between the two ends of the first resistor R1 drops to 0V, and the emitter and collector of the second switch tube Q2 are not turned on. Thus, the peak current between the digital output port DO and the reference ground is clamped at a reasonable value, effectively preventing the digital output circuit from being damaged due to short circuit and overcurrent.
[0034] The utility model also provides a motor driver, comprising the digital output circuit as described above.
[0035] The digital output circuit and motor controller of the utility model perform overcurrent protection on the digital output port through an overcurrent protection unit, do not need an additional power supply, have a simple circuit and low cost, and effectively prevent the digital output circuit from being damaged by short circuit and overcurrent without affecting the function of the digital output circuit.
[0036] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made according to the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.
Claims
1. A digital output circuit, comprising an optocoupler, a first switch tube and a digital output port, wherein the emitter of the optocoupler output end is connected to the control end of the first switch tube, and the collector serves as the digital output port, characterized in that: It also includes a first resistor and an overcurrent protection unit, the first resistor is connected in series at the digital output port, the overcurrent protection unit includes a first input end, a second input end and a first output end, the first input end and the second input end are respectively connected to the two ends of the first resistor, and the first output end is connected to the control end of the first switch tube.
2. The digital output circuit according to claim 1, characterized in that: A second resistor is further connected between the first resistor and the collector of the optocoupler output end.
3. The digital output circuit according to claim 1, characterized in that: The first switch tube is an NPN transistor.
4. The digital output circuit according to claim 3, characterized in that: The control end of the first switch tube is connected to its emitter via a third resistor and connected to a reference ground. The emitter of the first switch tube is connected to the second output end of the overcurrent protection unit, and the collector is connected to the digital output port.
5. The digital output circuit according to claim 4, characterized in that: The overcurrent protection unit includes a detection unit and a voltage clamping unit, the first input terminal and the second input terminal of the detection unit are respectively connected to the two ends of the first resistor, and the output terminal is connected to the control terminal of the voltage clamping unit. The voltage clamping unit clamps the voltage across the first resistor to a preset value according to the control signal output by the detection unit.
6. The digital output circuit according to claim 5, characterized in that: The detection unit includes a second switch tube, and the voltage clamping unit includes a third switch tube.
7. The digital output circuit according to claim 6, characterized in that: The voltage clamping unit further includes a fourth resistor and a fifth resistor connected in series with the fourth resistor, and the control end of the third switch tube is connected between the fourth resistor and the fifth resistor.
8. The digital output circuit according to claim 7, characterized in that: The second switch tube is a PNP transistor, the control end and the emitter of the second switch tube are respectively connected to the two ends of the first resistor, and the collector is connected to the control end of the third switch tube via the fourth resistor.
9. The digital output circuit according to claim 8, characterized in that: The third switch tube is an NPN transistor, the control end of the third switch tube is connected to its emitter via the fifth resistor and connected to the reference ground, and the collector is connected to the control end of the first switch tube.
10. A motor controller, characterized in that: The method comprises a digital output circuit as claimed in any one of claims 1 to 9.