An overvoltage and overcurrent protection circuit for an ultrasonic welding generator

Abstract

The utility model relates to an overvoltage and overcurrent protection circuit of ultrasonic welding generator relates to the circuit structure technical field of ultrasonic welding generator, solves the technical insufficient that present ultrasonic welding generator overvoltage, overcurrent protection exists, including current sampling circuit, current comparison circuit, voltage sampling circuit and voltage comparison circuit. Through the current transformer to the high frequency transformer primary side of ultrasonic welding generator carries out current collection, and the current that gathers with the reference current that singlechip gives compares through the comparator, when the current of high frequency transformer primary side exceeds the set value, the comparator gives the signal to singlechip, and singlechip output overcurrent alarm. Meanwhile, through the voltage transformer to the bridge arm power tube of ultrasonic welding generator parallel connection, when the voltage that appears abnormally on the upper and lower bridge arm of power tube, will detect the abnormal signal with the voltage that sets through the comparator compares, after exceeding, the comparator gives the signal to singlechip, and singlechip output overvoltage alarm.

Description

Technical Field

[0001] This utility model relates to the technical field of circuit structure of ultrasonic welding generators, and in particular to the improvement of the safety protection circuit structure of ultrasonic welding generators. Background Technology

[0002] Currently, the overvoltage and overcurrent protection measures of simulated ultrasonic welding generators on the market are not perfect. When abnormalities occur during tuning or operation, the tube is prone to burst, causing serious failures. Utility Model Content

[0003] To address the technical shortcomings of existing ultrasonic welding generator overvoltage and overcurrent protection, an overvoltage and overcurrent protection circuit for ultrasonic welding generators is proposed.

[0004] To address the technical shortcomings of this utility model, the adopted technical solution is as follows: An overvoltage and overcurrent protection circuit for an ultrasonic welding generator, characterized in that the protection circuit includes: The current sampling circuit collects the current from the primary side of the high-frequency transformer of the ultrasonic welding generator through a current transformer, and outputs the sampled current signal after rectification by a rectifier circuit. The current comparison circuit is used to compare the sampled current signal output by the current sampling circuit with the reference current signal output by the microcontroller of the ultrasonic welding generator. When the voltage of the sampled current signal is greater than the voltage of the reference current signal, an overcurrent alarm signal is output to the microcontroller of the ultrasonic welding generator. The voltage sampling circuit connects the bridge arm power transistors of the ultrasonic welding generator in parallel through a voltage transformer, collects the real-time voltage signal of the bridge arm power transistors in real time, and outputs the collected voltage after rectifying and filtering the collected real-time voltage signal. The voltage comparison circuit is used to compare the sampled voltage output by the voltage sampling circuit with the reference voltage output by the microcontroller of the ultrasonic welding generator. When the sampled voltage is greater than the reference voltage, an overvoltage alarm signal is output to the microcontroller of the ultrasonic welding generator.

[0005] The technical features that further define this utility model include: The current sampling circuit includes: a current detection sensor T5, diodes D20, D21, D22, and D23, resistors R43 and R47. The current detection sensor T5 is connected in series with the primary side of the high-frequency transformer TR1 of the ultrasonic welding generator to generate an induced voltage. This induced voltage is rectified by a bridge rectifier circuit composed of diodes D20, D21, D22, and D23. Resistors R43 and R47 are then connected in parallel with the output of the bridge rectifier circuit composed of diodes D20, D21, D22, and D23, ultimately outputting a relatively stable sampled current signal to the current comparison circuit.

[0006] The current comparison circuit includes an operational amplifier U3B; the sampled current signal output from the current sampling circuit is divided by resistors R62 and R65 and filtered by capacitor C37 before being input to the non-inverting input of operational amplifier U3B; the reference current signal output from the microcontroller is filtered by an integrating circuit consisting of resistors R71, capacitors C44, R73, C43, R70, C42, R69, C41, R72, and diode D27 before being input to the inverting input of operational amplifier U3B; the output of operational amplifier U3B is connected to the overcurrent signal input of the microcontroller.

[0007] The voltage sampling circuit includes: an upper bridge arm voltage sampling circuit and a lower bridge arm voltage sampling circuit; The upper bridge arm voltage sampling circuit includes: a current transformer T2, the primary winding of the current transformer T2 is connected in series with a diode D2 and then connected in parallel with the upper bridge arm power transistor, and the secondary winding of the current transformer T2 outputs the sampled voltage through a diode D1. The lower bridge arm voltage sampling circuit includes: a current transformer T3, the primary winding of the current transformer T3 is connected in series with diode D6 and then connected in parallel with the lower bridge arm power transistor, and the secondary winding of the current transformer T3 outputs the sampled voltage through diode D5; the upper bridge arm voltage sampling circuit and the lower bridge arm voltage sampling circuit share the same output terminal to output the sampled voltage.

[0008] The output of the upper bridge arm voltage sampling circuit is connected in parallel with a load resistor R8 and a filter capacitor C1; the secondary windings of the current transformer T2 and the current transformer T3 are respectively connected in parallel with diodes D4 and D9.

[0009] The voltage comparison circuit includes an operational amplifier U3A; the sampled voltage output from the voltage sampling circuit is divided by resistors R66 and R68 and filtered by capacitor C39 before being input to the non-inverting input of operational amplifier U3A; the reference voltage output from the microcontroller is filtered by an integrating circuit consisting of resistors R77, capacitors C48, R81, C47, R76, C46, ​​R75, C45, R80, and diode D28 before being input to the inverting input of operational amplifier U3A; the output of operational amplifier U3B is connected to the overcurrent signal input of the microcontroller.

[0010] The beneficial effects of this invention are as follows: This invention collects the current of the primary winding of the high-frequency transformer in the ultrasonic welding generator using a current transformer. The collected current is compared with a reference current provided by the microcontroller using a comparator. When the current of the primary winding of the high-frequency transformer exceeds a set value, the comparator sends a signal to the microcontroller, which then outputs an overcurrent alarm. Simultaneously, a voltage transformer is connected in parallel to the bridge arm power transistors of the ultrasonic welding generator. When an abnormality occurs in the voltage across the upper and lower bridge arms of the power transistors, the detected abnormal signal is compared with a set voltage using a comparator. If the voltage exceeds the set value, the comparator sends a signal to the microcontroller, which then outputs an overvoltage alarm. This invention combines analog and digital circuits, adding corresponding overvoltage and overcurrent detection circuits at relevant nodes. In the event of a fault, it can promptly protect the circuit from damage and issue an alarm signal. Attached Figure Description

[0011] Figure 1 This is a circuit diagram of the current sampling circuit and voltage sampling circuit of this utility model; Figure 2 This is a circuit diagram of the current comparison circuit of this utility model; Figure 3 This is a circuit diagram of the voltage comparison circuit of this utility model; Figure 4 This is the circuit diagram of the microcontroller section of an ultrasonic welding generator. Detailed Implementation

[0012] The structure of this utility model will be further described below with reference to the accompanying drawings and preferred embodiments.

[0013] Reference Figures 1 to 4 As shown in the figure, the overvoltage and overcurrent protection circuit of the ultrasonic welding generator disclosed in this utility model includes: a current sampling circuit, a current comparison circuit, a voltage sampling circuit, and a voltage comparison circuit.

[0014] The current sampling circuit collects the current from the primary side of the high-frequency transformer of the ultrasonic welding generator through a current transformer, and outputs the sampled current signal after rectification by a rectifier circuit. Its specific circuit structure includes: a current sensor T5, diodes D20, D21, D22, and D23, resistors R43 and R47. The current sensor T5 is connected in series with the primary side of the high-frequency transformer TR1 of the ultrasonic welding generator to generate an induced voltage. This induced voltage is rectified by a bridge rectifier circuit composed of diodes D20, D21, D22, and D23. Resistors R43 and R47 are then connected in parallel with the output of the bridge rectifier circuit composed of diodes D20, D21, D22, and D23, ultimately outputting a relatively stable sampled current signal to the current comparison circuit. When the primary current of the high-frequency transformer TR1 in the ultrasonic welding generator increases, the voltage at pins 1 and 3 of the current detection sensor T5 will increase. After being rectified by the bridge rectifier using diodes D20, D21, D22, and D23, the voltage is sent to... Figure 2 The resistor R62 is in the middle.

[0015] The current comparison circuit compares the sampled current signal output from the current sampling circuit with the reference current signal output from the microcontroller of the ultrasonic welding generator. When the voltage of the sampled current signal is greater than the voltage of the reference current signal, an overcurrent alarm signal is output to the microcontroller of the ultrasonic welding generator. Its specific circuit structure is as follows: The current comparison circuit includes an operational amplifier U3B; the sampled current signal output from the current sampling circuit is divided by resistors R62 and R65 and filtered by capacitor C37 before being input to the non-inverting input of operational amplifier U3B; the reference current signal output from the microcontroller is filtered by an integrating circuit consisting of resistors R71, capacitors C44, R73, C43, R70, C42, R69, C41, R72, and diode D27 before being input to the inverting input of operational amplifier U3B; the output of operational amplifier U3B is connected to the overcurrent signal input of the microcontroller. In other words, the sampled current signal output by the current sampling circuit is divided by resistors R62 and R65 and then sent to pin 5 of operational amplifier U3B. It is then compared with the voltage connected to pin 6 of operational amplifier U3B. When the voltage at pin 5 of operational amplifier U3B is greater than the voltage at pin 6, pin 7 of operational amplifier U3B outputs an overcurrent alarm signal. Figure 4 Pin 21 of the microcontroller U4 in the ultrasonic welding generator is used to provide a basis for the microcontroller to make an abnormal current judgment. Based on this basis, the microcontroller sends the information to the display circuit to prompt the user of an overcurrent fault.

[0016] The voltage sampling circuit connects the bridge arm power transistors of the ultrasonic welding generator in parallel via a voltage transformer to acquire the real-time voltage signal of the bridge arm power transistors. The acquired real-time voltage signal is rectified and filtered before being output as the acquired voltage. The specific circuit structure is as follows: the voltage sampling circuit includes an upper bridge arm voltage sampling circuit and a lower bridge arm voltage sampling circuit.

[0017] The upper bridge arm voltage sampling circuit includes: a current transformer T2, with the primary winding of the current transformer T2 connected in series with diode D2 and then connected in parallel with the upper bridge arm power transistor; the secondary winding of the current transformer T2 outputs the sampled voltage via diode D1; the upper bridge arm power transistor refers to... Figure 1 The six transistors Q1 to Q6 are connected in parallel.

[0018] The lower bridge arm voltage sampling circuit includes: a current transformer T3, with the primary winding of the current transformer T3 connected in series with diode D6 and then in parallel with the lower bridge arm power transistor; the secondary winding of the current transformer T3 outputs the sampled voltage via diode D5; the upper bridge arm voltage sampling circuit and the lower bridge arm voltage sampling circuit share the same output terminal to output the sampled voltage. The lower bridge arm power transistor refers to... Figure 1 The six transistors Q7 to Q12 are connected in parallel.

[0019] To ensure a smooth and stable voltage output from the voltage sampling circuit, a load resistor R8 and a filter capacitor C1 are connected in parallel at the output of the upper bridge arm voltage sampling circuit; diodes D4 and D9 are connected in parallel at the secondary windings of the current transformer T2 and the secondary windings of the current transformer T3, respectively.

[0020] That is to say, in Figure 1 In the circuit, the primary winding of current transformer T2 is connected in series with diode D2, and then in parallel with the upper bridge power transistors Q1 to Q6. According to the principle that the voltages in parallel circuits are equal, when the voltages of the upper bridge power transistors Q1 to Q6 are abnormal, the voltages at pins 7 and 10 of the secondary winding of current transformer T2 will increase. After rectification by diode D1 and filtering by capacitor C1, the voltage is sent to the circuit. Figure 3 The resistor R66 terminal in the middle.

[0021] The voltage comparison circuit compares the voltage sampled by the voltage sampling circuit with the reference voltage output by the microcontroller of the ultrasonic welding generator. When the sampled voltage exceeds the reference voltage, an overvoltage alarm signal is output to the microcontroller of the ultrasonic welding generator. Specifically, the voltage comparison circuit includes an operational amplifier U3A. The sampled voltage output by the voltage sampling circuit is divided by resistors R66 and R68 and filtered by capacitor C39 before being input to the non-inverting input of operational amplifier U3A. The reference voltage output by the microcontroller is filtered by an integrating circuit consisting of resistors R77, capacitors C48, R81, C47, R76, C46, ​​R75, C45, R80, and diode D28 before being input to the inverting input of operational amplifier U3A. The output of operational amplifier U3B is connected to the overcurrent signal input of the microcontroller. That is... Figure 3 Resistors R66 and R68 divide the sampling voltage output from the upper bridge arm voltage sampling circuit and send it to pin 3 of operational amplifier U3A. Operational amplifier U3A compares this voltage with the reference voltage output from the microcontroller (input pin 2). When the voltage at pin 3 of operational amplifier U3A is greater than the voltage at pin 2, pin 1 of operational amplifier U3A outputs an overvoltage alarm signal. Figure 4 Pin 27 of the microcontroller U4 in the ultrasonic welding generator provides the microcontroller with the basis for overvoltage judgment. Based on this basis, microcontroller U4 sends the information to the display circuit to alert the user of an overvoltage fault. The reference voltage input to pin 2 of operational amplifier U3A is provided by pin 39 of microcontroller U4, filtered by an integrating circuit consisting of resistor R77, capacitor C48, resistor R81, capacitor C47, resistor R76, capacitor C46, ​​resistor R75, capacitor C45, resistor R80, and diode D28. Similarly, when an abnormally large voltage occurs at pins 7 and 10 of the secondary winding of current transformer T3, it is rectified by diode D5 and filtered by capacitor C1 before being sent to resistor R66. Operational amplifier U3A compares this voltage with the reference voltage output from the microcontroller at pin 2. When the voltage at pin 3 of operational amplifier U3A is greater than the voltage at pin 2, pin 1 of operational amplifier U3A outputs an overvoltage alarm signal.

[0022] This invention combines analog and digital circuits, adding corresponding overvoltage and overcurrent detection circuits at relevant nodes. In the event of a fault, it can protect the circuit from damage and issue an alarm signal in a timely manner.

Claims

1. An overvoltage and overcurrent protection circuit for an ultrasonic welding generator, characterized in that... The protection circuit includes: The current sampling circuit collects the current from the primary side of the high-frequency transformer of the ultrasonic welding generator through a current transformer, and outputs the sampled current signal after rectification by a rectifier circuit. The current comparison circuit is used to compare the sampled current signal output by the current sampling circuit with the reference current signal output by the microcontroller of the ultrasonic welding generator. When the voltage of the sampled current signal is greater than the voltage of the reference current signal, an overcurrent alarm signal is output to the microcontroller of the ultrasonic welding generator. The voltage sampling circuit connects the bridge arm power transistors of the ultrasonic welding generator in parallel through a voltage transformer, collects the real-time voltage signal of the bridge arm power transistors in real time, and outputs the collected voltage after rectifying and filtering the collected real-time voltage signal. The voltage comparison circuit is used to compare the sampled voltage output by the voltage sampling circuit with the reference voltage output by the microcontroller of the ultrasonic welding generator. When the sampled voltage is greater than the reference voltage, an overvoltage alarm signal is output to the microcontroller of the ultrasonic welding generator.

2. The overvoltage and overcurrent protection circuit for an ultrasonic welding generator according to claim 1, characterized in that: The current sampling circuit includes: a current detection sensor T5, diodes D20, D21, D22, and D23, resistors R43 and R47. The current detection sensor T5 is connected in series with the primary side of the high-frequency transformer TR1 of the ultrasonic welding generator to generate an induced voltage. This induced voltage is rectified by a bridge rectifier circuit composed of diodes D20, D21, D22, and D23. Resistors R43 and R47 are then connected in parallel with the output of the bridge rectifier circuit composed of diodes D20, D21, D22, and D23, ultimately outputting a relatively stable sampled current signal to the current comparison circuit.

3. The overvoltage and overcurrent protection circuit for an ultrasonic welding generator according to claim 1, characterized in that: The current comparison circuit includes an operational amplifier U3B; the sampled current signal output from the current sampling circuit is divided by resistors R62 and R65 and filtered by capacitor C37 before being input to the non-inverting input of operational amplifier U3B; the reference current signal output from the microcontroller is filtered by an integrating circuit consisting of resistors R71, capacitors C44, R73, C43, R70, C42, R69, C41, R72, and diode D27 before being input to the inverting input of operational amplifier U3B; the output of operational amplifier U3B is connected to the overcurrent signal input of the microcontroller.

4. The overvoltage and overcurrent protection circuit for an ultrasonic welding generator according to claim 1, characterized in that: The voltage sampling circuit includes: an upper bridge arm voltage sampling circuit and a lower bridge arm voltage sampling circuit; The upper bridge arm voltage sampling circuit includes: a current transformer T2, the primary winding of the current transformer T2 is connected in series with a diode D2 and then connected in parallel with the upper bridge arm power transistor, and the secondary winding of the current transformer T2 outputs the sampled voltage through a diode D1. The lower bridge arm voltage sampling circuit includes: a current transformer T3, the primary winding of the current transformer T3 is connected in series with diode D6 and then connected in parallel with the lower bridge arm power transistor, and the secondary winding of the current transformer T3 outputs the sampled voltage through diode D5; the upper bridge arm voltage sampling circuit and the lower bridge arm voltage sampling circuit share the same output terminal to output the sampled voltage.

5. The overvoltage and overcurrent protection circuit for an ultrasonic welding generator according to claim 4, characterized in that: The output of the upper bridge arm voltage sampling circuit is connected in parallel with a load resistor R8 and a filter capacitor C1; the secondary windings of the current transformer T2 and the current transformer T3 are respectively connected in parallel with diodes D4 and D9.

6. The overvoltage and overcurrent protection circuit for an ultrasonic welding generator according to claim 1, characterized in that: The voltage comparison circuit includes an operational amplifier U3A; the sampled voltage output from the voltage sampling circuit is divided by resistors R66 and R68 and filtered by capacitor C39 before being input to the non-inverting input of operational amplifier U3A; the reference voltage output from the microcontroller is filtered by an integrating circuit consisting of resistors R77, capacitors C48, R81, C47, R76, C46, ​​R75, C45, R80, and diode D28 before being input to the inverting input of operational amplifier U3A; the output of operational amplifier U3B is connected to the overcurrent signal input of the microcontroller.

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