Direct-current fan power supply circuit for inverter welding machine cooling

Abstract

The application relates to a direct-current fan power supply circuit for cooling an inverter welding machine, which comprises a welding machine input circuit and a control circuit; a voltage input end of the welding machine input circuit is connected with a voltage output end of a welding machine transformer, a voltage output end is connected with a first voltage input end of the control circuit, and the first voltage input end is used for transmitting an alternating voltage to the control circuit based on the welding machine transformer; a voltage output end of the control circuit is connected with a voltage input end of a direct-current fan, and the voltage output end is used for outputting a direct-current working voltage to the voltage input end of the direct-current fan after modulating the alternating voltage into the direct-current working voltage. The welding machine input circuit is used for obtaining the alternating voltage from the welding machine transformer as the original voltage provided to the direct-current fan, and a switching power supply is not used to provide the original voltage to the direct-current fan, so that the failure rate of the power supply circuit is reduced. The application has the effects of reducing the amount of dust accumulation in the inverter welding machine, improving the power supply reliability of the fan, prolonging the service life of the fan and prolonging the service life of the inverter welding machine.

Description

Technical Field

[0001] This invention relates to the field of inverter welding machine cooling, and in particular to a DC fan power supply circuit for inverter welding machine cooling. Background Technology

[0002] During the use of inverter welding machines, the machines themselves generate a lot of heat, requiring external cooling equipment. This is especially true for high-power inverter welding machines, which have high requirements for heat dissipation of power devices and necessitate the use of high-power cooling equipment.

[0003] Existing cooling equipment typically uses DC fans. During operation, a switching power supply is required to convert AC voltage to DC voltage to provide the necessary operating conditions for the DC fan. However, switching power supplies have a relatively high failure rate, especially high-power ones, making it difficult to guarantee the reliability of the power supply to the DC fan. Summary of the Invention

[0004] To help improve the power supply reliability of DC fans, this invention provides a DC fan power supply circuit for cooling inverter welding machines.

[0005] The DC fan power supply circuit for cooling an inverter welding machine provided in this application adopts the following technical solution: A DC fan power supply circuit for cooling an inverter welding machine includes a welding machine input circuit and a control circuit; The voltage input terminal of the welding machine input circuit is connected to the voltage output terminal of the welding machine transformer, and the voltage output terminal is connected to the first voltage input terminal of the control circuit, for transmitting AC voltage to the first voltage input terminal of the control circuit based on the welding machine transformer; The voltage output terminal of the control circuit is connected to the voltage input terminal of the DC fan. It is used to modulate the AC voltage into the DC operating voltage required by the DC fan and then output the DC operating voltage to the voltage input terminal of the DC fan.

[0006] By adopting the above technical solution, the primary windings of existing inverter welding machine transformers are all connected to the inverter main circuit, reducing the number of power semiconductor devices contained in the inverter welding machine transformer itself. Compared to switching power supplies, which contain a larger number of power semiconductor devices such as diodes and transistors, the higher the power of the switching power supply, the more power semiconductor devices are required, and the higher the failure rate. This application obtains AC voltage from the welding machine transformer through the welding machine input circuit and transmits the AC voltage to the control circuit. After modulating the AC voltage, the control circuit outputs it to the voltage input terminal of the DC fan for operation. Since the failure rate of the welding machine transformer is relatively lower than that of the switching power supply, the power supply stability of the fan is improved, thereby helping to improve the power supply reliability of the fan.

[0007] Optionally, the power supply circuit may further include a power supply circuit for supplying power to the welding machine control board; The first voltage output terminal of the power supply circuit is connected to the voltage input terminal of the welding machine control board, and the second voltage output terminal is connected to the second voltage input terminal of the control circuit, for transmitting DC voltage to the second voltage input terminal of the control circuit; The control circuit is used to receive the DC voltage transmitted from the power supply circuit to the second voltage input terminal when there is no AC voltage at the first voltage input terminal, and modulate the DC voltage to the DC operating voltage required by the DC fan.

[0008] By adopting the above technical solution, when the inverter welding machine is in overheat protection mode, it stops working, the welding machine transformer cannot generate AC voltage, and the welding machine input circuit cannot transmit AC power to the first voltage input terminal of the control circuit. At this time, the control circuit receives the DC voltage transmitted from the power supply circuit and modulates it into the DC operating voltage required by the DC fan to power the DC fan. On the one hand, this facilitates continuous power supply to the DC fan, ensuring the reliability of the fan's power supply; on the other hand, the switching power supply is only used when the inverter welding machine is in overheat protection mode, which reduces the time the switching power supply powers the DC fan, effectively reducing the workload of the switching power supply and making it less prone to damage; it also extends the service life of the switching power supply and further improves the reliability of the fan's power supply.

[0009] Furthermore, since the power supply circuit is used to provide operating voltage to the welding machine control board, its maximum output power is limited. However, the power supply circuit only provides the initial current to the DC fan when the inverter welding machine is in overheat protection mode. That is, even if the power supply circuit cannot provide the power required by the DC fan, it can still drive the DC fan to rotate and dissipate heat for the inverter welding machine. After the inverter welding machine is out of overheat protection mode, the welding machine input circuit resumes AC power supply, providing the required power to the DC fan. This allows for the use of a low-power power supply circuit to drive a high-power DC fan. Low-power power supply circuits have a low failure rate and low cost, which helps improve the reliability of the fan's power supply.

[0010] Optionally, the control circuit is connected to a temperature detection circuit; The temperature detection circuit is used to detect the temperature of the welding machine, and its resistance decreases when the temperature of the welding machine increases. The control circuit is used to increase the DC operating voltage when the resistance of the temperature detection circuit decreases, and to decrease the DC operating voltage when the resistance of the temperature detection circuit increases.

[0011] By adopting the above technical solution, the control circuit is connected to the temperature detection circuit. When the resistance of the temperature detection circuit changes, the control circuit changes the output DC operating voltage. On the one hand, this achieves stepless adjustment of the DC fan speed based on the temperature of the inverter welding machine; that is, when the inverter welding machine temperature is high, the DC fan voltage increases, and the DC fan speed increases; when the inverter welding machine temperature is low, the DC fan voltage decreases, and the DC fan speed decreases. This facilitates meeting the heat dissipation requirements of the inverter welding machine and extends the service life of the DC fan. On the other hand, since the DC fan speed does not maintain a continuous high-speed operation as the inverter welding machine's temperature changes, it helps to alleviate the problem of dust accumulation inside the inverter welding machine, thus facilitating heat dissipation.

[0012] Optionally, the control circuit includes a rectifier filter sub-circuit, an automatic control sub-circuit, a voltage regulator chip, and a buck sub-circuit; The voltage input terminal of the rectifier filter sub-circuit is connected to the first voltage input terminal of the control circuit, and the voltage output terminal is connected to the voltage input pin of the voltage regulator chip. The voltage input terminal of the automatic control sub-circuit is connected to the second voltage input terminal of the control circuit, and the voltage output terminal is connected to the voltage input pin of the voltage regulator chip. The voltage output pin of the voltage regulator chip is connected to the voltage input terminal of the buck sub-circuit, and the voltage output terminal of the buck sub-circuit is connected to the voltage output terminal of the control circuit.

[0013] By adopting the above technical solution, the rectifier and filter sub-circuit is connected to the first voltage input terminal of the control circuit, facilitating the rectification and filtering of the AC voltage transmitted from the welding machine input circuit, converting the AC voltage into DC voltage, and providing the required voltage for the DC fan. The voltage input terminal of the automatic control sub-circuit is connected to the second voltage input terminal of the control circuit, facilitating the orderly input of AC and DC voltages; that is, when there is no AC voltage input at the first voltage input terminal of the control circuit, the second voltage input terminal of the control circuit is connected to the voltage input pin of the voltage regulator chip, facilitating the reception of DC voltage transmitted from the power supply circuit, and providing the required voltage for the DC fan. The voltage regulator chip and the step-down sub-circuit modulate the voltage input to the voltage input pin of the voltage regulator chip to the DC operating voltage required by the DC fan, thus meeting the operating requirements of the DC fan.

[0014] Optionally, the welding machine input circuit includes a coil wound on the secondary side of the welding machine transformer core and the same-named terminal and opposite-named terminal of the coil; The rectifier-filter sub-circuit includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first capacitor C1, and a second capacitor C2. The anode of the first diode D1 is connected to its corresponding terminal, and its cathode is connected to the voltage output terminal of the rectifier-filter sub-circuit. The anode of the second diode D2 is connected to its opposite terminal, and its cathode is connected to the voltage output terminal of the rectifier-filter sub-circuit. The cathode of the third diode D3 is connected to its corresponding terminal, and its anode is grounded. The cathode of the fourth diode D4 is connected to its opposite terminal, and its anode is grounded. The positive terminal of the first capacitor C1 is connected to the voltage output terminal of the rectifier-filter sub-circuit, and its negative terminal is grounded. The positive terminal of the second capacitor C2 is connected to the voltage output terminal of the rectifier-filter sub-circuit, and its negative terminal is grounded. The automatic control sub-circuit includes a second resistor R2, a third resistor R3, and a fifth diode D5; one end of the second resistor R2 is connected to the voltage input terminal of the automatic control sub-circuit, and the other end is connected to the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the voltage output terminal of the automatic control sub-circuit; the third resistor R3 is connected in parallel with the second resistor R2. The step-down sub-circuit includes a sixth diode D6 and an inductor L; the anode of the sixth diode D6 is grounded, and the cathode is connected to the voltage output terminal of the step-down chip; one end of the inductor L is connected in parallel with the cathode of the sixth diode D6 to the voltage output terminal of the step-down chip, and the other end is connected to the voltage output terminal of the step-down sub-circuit.

[0015] By adopting the above technical solution, the welding machine input circuit is configured with a coil independently wound on the secondary side of the welding machine transformer core. This facilitates the modulation of the AC voltage transmitted to the rectifier and filter sub-circuit to better match the operating voltage required by the DC fan. The rectifier section of the rectifier and filter sub-circuit uses four diodes to form a bridge rectifier circuit, which improves current utilization. The filter section uses two capacitors to enhance the filtering effect. The automatic control sub-circuit uses a single diode to achieve automatic switching between AC and DC voltage input voltage regulator chips. The circuit structure is simple, reducing the number of power components required.

[0016] Optionally, the control circuit further includes a feedback sub-circuit, the voltage input terminal of which is connected to the voltage output terminal of the buck sub-circuit, and the voltage output terminal is connected to the voltage feedback pin of the voltage regulator chip. The feedback sub-circuit is connected to the temperature detection circuit; The voltage regulating chip is used to adjust the duty cycle and change the output voltage based on the feedback voltage value input from the voltage feedback pin.

[0017] By adopting the above technical solution, the voltage input terminal of the feedback sub-circuit is connected to the voltage output terminal of the step-down sub-circuit, thus obtaining the voltage output of the control circuit. Based on the voltage output of the control circuit and the responsiveness of the temperature detection circuit to the inverter welding machine's temperature, the voltage output of the control circuit, i.e., the DC operating voltage, is adjusted. This allows for different DC operating voltages to be output according to the inverter welding machine's temperature, thereby changing the operating power of the DC fan. This not only meets the heat dissipation requirements of the inverter welding machine but also extends the service life of the DC fan. It also prevents the DC fan from continuously operating at high power.

[0018] Optionally, the feedback sub-circuit includes a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6; One end of the fourth resistor R4 is connected to the voltage input terminal of the feedback sub-circuit, and the other end is connected to the fifth resistor R5; the end of the fifth resistor R5 furthest from the fourth resistor R4 is grounded; the voltage input terminal of the temperature detection circuit is connected to the connection node of the fourth resistor R4 and the fifth resistor R5, and the voltage output terminal is connected to one end of the sixth resistor R6; the other end of the sixth resistor R6 is grounded. The temperature detection circuit includes a thermistor R0, one end of which is connected to the voltage input terminal of the temperature detection circuit, and the other end of which is connected to the voltage output terminal of the temperature detection circuit.

[0019] By adopting the above technical solution, the temperature detection circuit uses a thermistor, which is positioned near ground. When the temperature of the inverter welding machine changes, the resistance of the thermistor changes, automatically and in real-time transmitting the corresponding voltage to the voltage feedback pin of the voltage regulator chip based on the temperature change of the inverter welding machine. This allows the voltage regulator chip to adjust the DC operating voltage transmitted to the DC fan in real time, facilitating the adjustment of the DC fan speed.

[0020] Optionally, the feedback sub-circuit further includes a seventh resistor R7 and a seventh diode D7; One end of the seventh resistor R7 is connected to the connection node of the fourth resistor R4 and the fifth resistor R5, and the other end is connected to the anode of the seventh diode D7; the cathode of the seventh diode D7 is connected to the end of the fourth resistor R4 away from the fifth resistor R5.

[0021] By adopting the above technical solution, the seventh resistor and the seventh diode facilitate limiting the maximum output voltage of the voltage regulator chip. Specifically, when the DC operating voltage output by the voltage regulator chip exceeds a preset value, the seventh diode D7 breaks down and conducts in reverse. At this time, the seventh resistor is added to the feedback sub-circuit, changing the voltage received by the voltage feedback pin of the voltage regulator chip, thereby reducing the output DC operating voltage of the voltage regulator chip and ensuring that the DC fan is not easily damaged.

[0022] Optionally, the control circuit further includes a power-on indicator sub-circuit and a re-filtering sub-circuit; The voltage input terminal of the power-on indicator sub-circuit is connected to the voltage input pin of the voltage regulator chip, and the voltage output terminal is grounded. It is used to output power-on indicator information when there is a voltage input at the voltage input pin of the voltage regulator chip. The re-filtering sub-circuit is connected to the buck sub-circuit and is used to re-filter the output voltage of the buck sub-circuit.

[0023] By adopting the above technical solution, the power-on indicator subcircuit allows relevant personnel to easily determine whether there is voltage input at the voltage input pin of the voltage regulator chip, thus enabling timely maintenance of the power supply circuit when there is no voltage input at the voltage input pin of the voltage regulator chip. This facilitates the restoration of DC fan operation on one hand, and facilitates heat dissipation for the inverter welding machine on the other, contributing to improved power supply reliability for the DC fan. The re-filtering subcircuit further filters the voltage output from the buck subcircuit, reducing the AC component in the DC operating voltage, thereby improving the power supply reliability of the fan and extending its service life.

[0024] Optionally, the power-on indicator sub-circuit includes a first resistor R1 and a light-emitting diode D0; One end of the first resistor R1 is connected to the voltage input pin of the voltage regulator chip, and the other end is connected to the anode of the light-emitting diode D0, while the cathode of the light-emitting diode D0 is grounded; The re-filtering sub-circuit includes several capacitors, which are connected in parallel between the output voltage of the step-down sub-circuit and the ground terminal.

[0025] By adopting the above technical solution, the light-emitting diode D0 can easily provide a prompt to the staff. Several capacitors facilitate further filtering of the DC operating voltage, improving its stability.

[0026] In summary, firstly, by utilizing the welding machine's input circuit to obtain AC voltage from the welding machine transformer as the initial voltage supplied to the DC fan, a switching power supply was not used. This approach offers advantages such as a low failure rate for the welding machine transformer and the availability of AC voltage from the welding machine's input circuit to meet the operational requirements of high-power DC fans. This contributes to improving the power supply reliability of the fan.

[0027] Secondly, the power supply circuit that powers the welding machine control board provides a backup DC voltage to the control circuit, ensuring that the control circuit still has voltage input when the inverter welding machine is in overheat protection mode, thus ensuring that the DC fan is in operation and dissipating heat from the inverter welding machine.

[0028] Furthermore, the temperature detection circuit is connected to the control circuit, and together with the control circuit, the speed of the DC fan is adjusted. This allows the DC fan speed to be slowed down when the inverter welding machine temperature drops and sped up when the inverter welding machine temperature rises. This meets the heat dissipation requirements of the welding machine and helps to extend the lifespan of the inverter welding machine, the DC fan, and the power supply circuit. Attached Figure Description

[0029] Figure 1 This is an overall block diagram of a DC fan power supply circuit for cooling an inverter welding machine, according to an embodiment of this application.

[0030] Figure 2 This is a circuit diagram of a control circuit for a DC fan power supply circuit used for cooling an inverter welding machine, according to an embodiment of this application.

[0031] Explanation of reference numerals in the attached figures: 1. Welding machine input circuit; 2. Control circuit; 21. Rectifier and filter sub-circuit; 22. Power-on indicator sub-circuit; 23. Automatic control sub-circuit; 24. Voltage regulator chip; 25. Step-down sub-circuit; 26. Feedback sub-circuit; 27. Re-filter sub-circuit; 3. Power supply circuit; 4. Temperature detection circuit; 10. Welding machine transformer; 20. DC fan; 30. Welding machine control board. Detailed Implementation

[0032] This application discloses a DC fan power supply circuit for cooling an inverter welding machine. (Refer to...) Figure 1 It includes a welding machine input circuit 1, a control circuit 2, a power supply circuit 3, and a temperature detection circuit 4. The welding machine input circuit 1 and the power supply circuit 3 are both used to provide input voltage to the control circuit 2; the temperature detection circuit 4 is used to detect the temperature of the inverter welding machine; based on the temperature of the inverter welding machine detected by the temperature detection circuit 4 and the input voltage, the control circuit 2 outputs the DC operating voltage required by the DC fan 20 to ensure the operation of the DC fan 20 and to dissipate heat for the inverter welding machine.

[0033] The voltage input terminal of the welding machine input circuit 1 is connected to the voltage output terminal of the welding machine transformer 10, and the voltage output terminal is connected to the first voltage input terminal CN1 of the control circuit 2, for transmitting AC voltage from the welding machine transformer 10 to the first voltage input terminal CN1 of the control circuit 2. The voltage output terminal of the control circuit 2 is connected to the voltage input terminal of the DC fan 20, for modulating the AC voltage to the DC operating voltage required by the DC fan 20, and then outputting the DC operating voltage to the voltage input terminal of the DC fan 20.

[0034] Specifically, in one embodiment, the welding machine input circuit 1 includes a coil wound on the secondary side of the welding machine transformer 10 core, and the same-named and opposite-named terminals of the coil. It should be noted that the welding machine transformer 10 in this embodiment refers to the high-frequency transformer integrated into the inverter welding machine. This high-frequency transformer can be wound with a ferrite core or a microcrystalline core, and has three windings, N1 to N3. N1 is the primary winding, connected to the inverter main circuit; N2 and N3 are two secondary windings, which provide voltage to the welding circuit of the inverter welding machine through a rectifier circuit composed of two diodes. The inverter main circuit is also a built-in structure of the inverter welding machine and can be a full-bridge circuit, a half-bridge circuit, or a single-ended circuit. The coil of the welding machine input circuit 1 is wound on the same side of the transformer core as N2 and N3. The number of turns of the coil is affected by the primary voltage of the welding machine transformer 10, the number of turns of the primary coil, and the rated voltage of the DC fan 20.

[0035] For example, in this embodiment, N1 has 24 turns, and N2 and N3 each have 3 turns; the inverter welding machine is connected to a 380V AC mains voltage, and the voltage across N1 is approximately 537V. For ease of explanation, we will consider the voltage across N1 to be 540V; there are two DC fans 20, both 24V, 1.3A. Therefore, the number of turns in the coil is set to 2 turns, with a turns ratio of 12:1 to N1, and the output voltage of the welding machine input circuit 1 is 45V. That is, the output voltage of the welding machine input circuit 1, after modulation by the control circuit 2, is sufficient to meet the requirements of the DC fan 20.

[0036] Reference Figure 1 The power supply circuit 3 is used to supply power to the welding control board 30 of the inverter welding machine. Specifically, the first voltage output terminal of the power supply circuit 3 is connected to the voltage input terminal of the welding control board 30; the second voltage output terminal is connected to the second voltage input terminal CN2 of the control circuit 2, and is used to transmit DC voltage to the second voltage input terminal CN2 of the control circuit 2.

[0037] It should be noted that power supply circuit 3 is a switching power supply, and power supply circuit 3 is a low-power switching power supply used to provide operating voltage to the welding machine control board 30 of the inverter welding machine. In this embodiment, low-power switching power supply refers to a switching power supply with a power of less than 30 watts or 50 watts; high-power switching power supply refers to a switching power supply with a power of greater than or equal to 30 watts, or it can be a switching power supply with a power of greater than or equal to 50 watts; low-power DC fan refers to a DC fan with a power of less than 60 watts, commonly 20-watt and 30-watt DC fans; high-power DC fan refers to a DC fan with a power of greater than or equal to 60 watts. Specifically, power supply circuit 3 transmits 17V DC voltage to the second voltage input terminal of control circuit 2. It is easy to understand that after the 17V DC voltage transmitted from the second voltage output terminal of power supply circuit 3 is modulated by control circuit 2, the DC voltage will be further reduced. When the DC fan 20 is a high-power DC fan, the DC voltage transmitted to the DC fan 20 is difficult to guarantee that the DC fan 20 can operate at its maximum output power, resulting in a decrease in the speed of the DC fan 20.

[0038] However, in order to ensure the heat dissipation requirements of the inverter welding machine, the control circuit 2 is used to receive the DC voltage transmitted from the power supply circuit 3 to the second voltage input terminal CN2 when there is no AC voltage at the first voltage input terminal CN1, and modulate the DC voltage to the DC operating voltage required by the DC fan 20; when there is AC voltage at the first voltage input terminal CN1, the second voltage input terminal CN2 is disconnected and the DC voltage transmitted from the power supply circuit 3 to the second voltage input terminal CN2 is no longer received; this is to ensure that the DC fan 20 can work at its maximum output power and improve the heat dissipation capacity of the DC fan 20.

[0039] It's easy to understand that the AC voltage transmitted by the welding machine input circuit 1 is used first to provide the required DC operating voltage for the DC fan 20, allowing it to operate at high power. When the inverter welding machine is in overheat protection mode, it stops working, and there is no AC voltage on the primary side and no AC voltage output on the secondary side of the welding machine transformer 10. At this time, the DC voltage transmitted by the power supply circuit 3 is used. Although this makes it easier for the DC fan 20 to operate at low power, the DC fan 20 still has a heat dissipation function, which helps to reduce the temperature of the inverter welding machine, allowing it to escape the overheat protection state and restart operation.

[0040] Reference Figure 1 The temperature detection circuit 4 is connected to the peripheral interface CN3 of the control circuit 2 and is used to detect the welding machine temperature. When the welding machine temperature rises, the resistance decreases; when the welding machine temperature falls, the resistance increases. Here, "resistance" refers to the total resistance of the temperature detection circuit 4. The control circuit 2 increases the DC operating voltage when the resistance of the temperature detection circuit 4 decreases and decreases the DC operating voltage when the resistance of the temperature detection circuit 4 increases.

[0041] Specifically, refer to Figure 2 The control circuit 2 includes a rectifier-filter sub-circuit 21, a power-on indicator sub-circuit 22, an automatic control sub-circuit 23, a voltage regulator chip 24, a buck sub-circuit 25, a feedback sub-circuit 26, and a re-filter sub-circuit 27. The voltage input terminal of the rectifier-filter sub-circuit 21 is connected to the first voltage input terminal CN1 of the control circuit 2, and its voltage output terminal is connected to the voltage input pin VIN of the voltage regulator chip 24. The voltage input terminal of the automatic control sub-circuit 23 is connected to the second voltage input terminal CN2 of the control circuit 2, and its voltage output terminal is connected to the voltage input pin VIN of the voltage regulator chip 24. The voltage input terminal of the power-on indicator sub-circuit 22 is connected to the voltage input pin VIN of the voltage regulator chip 24, and its voltage output terminal is grounded. It outputs a power-on indicator message when there is voltage input at the voltage input pin VIN of the voltage regulator chip 24. The voltage output pin OUT of the voltage regulator chip 24 is connected to the voltage input terminal of the buck sub-circuit 25, and the voltage output terminal of the buck sub-circuit 25 is connected to the voltage output terminal of the control circuit 2.

[0042] It should be noted that, in combination Figure 1 In this embodiment, the control circuit 2 is provided with two voltage output interfaces, namely a first output interface CN4 and a second output interface CN5. The voltage output terminal of the control circuit 2 is connected to both voltage output interfaces. The first output interface CN4 is used to connect to the voltage input terminal of one DC fan 20, and the second output interface CN5 is used to connect to the voltage input terminal of another DC fan 20.

[0043] Reference Figure 2 The voltage input terminal of the feedback sub-circuit 26 is connected to the voltage output terminal of the buck sub-circuit 25, and the voltage output terminal is connected to the voltage feedback pin FB of the voltage regulator chip 24. It should be noted that the feedback sub-circuit 26 is connected to the temperature detection circuit 4 through the peripheral interface CN3 of the control circuit 2. The voltage regulator chip 24 is used to adjust the duty cycle based on the feedback voltage value input at the voltage feedback pin FB, thereby changing the output voltage. The re-filtering sub-circuit 27 is connected to the buck sub-circuit 25 and is used to re-filter the output voltage of the buck sub-circuit 25.

[0044] Reference Figure 1 and Figure 2The rectifier-filter sub-circuit 21 may include a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first capacitor C1, and a second capacitor C2. The anode of the first diode D1 is connected to the same-name terminal of the welding machine input circuit 1, and its cathode is connected to the voltage output terminal of the rectifier-filter sub-circuit 21. The anode of the second diode D2 is connected to the opposite-name terminal of the welding machine input circuit 1, and its cathode is connected to the voltage output terminal of the rectifier-filter sub-circuit 21. The cathode of the third diode D3 is connected to the same-name terminal of the welding machine input circuit 1, and its anode is grounded. The cathode of the fourth diode D4 is connected to the opposite-name terminal of the welding machine input circuit 1, and its anode is grounded. The first diode D1, second diode D2, third diode D3, and fourth diode D4 form a bridge rectifier circuit, facilitating the conversion of AC voltage to DC voltage. Alternatively, the rectifier section of the rectifier-filter sub-circuit 21 can also be a full-wave rectifier circuit, i.e., a rectifier circuit using only two diodes.

[0045] The positive terminal of the first capacitor C1 is connected to the voltage output terminal of the rectifier-filter sub-circuit 21, and the negative terminal is grounded; the positive terminal of the second capacitor C2 is connected to the voltage output terminal of the rectifier-filter sub-circuit 21, and the negative terminal is grounded. That is, the first capacitor C1 and the second capacitor C2 are connected in parallel, and in this embodiment, both the first capacitor C1 and the second capacitor C2 are polarized capacitors, which helps to improve the filtering effect.

[0046] Reference Figure 1 The power-on indicator sub-circuit 22 includes a first resistor R1 and a light-emitting diode D0. One end of the first resistor R1 is connected to the voltage input pin VIN of the voltage regulator chip 24, and the other end is connected to the anode of the light-emitting diode D0; the cathode of the light-emitting diode D0 is grounded. When there is a voltage input to the voltage input pin VIN of the voltage regulator chip 24, the power-on indicator sub-circuit 22 will also have a voltage input, causing the light-emitting diode D0 to light up, making it easy for operators to know the power-on status of the control circuit 2. It is easy to understand that the light emitted by the light-emitting diode D0 is the power-on indication information output by the power-on indicator sub-circuit 22.

[0047] The automatic control sub-circuit 23 includes a second resistor R2, a third resistor R3, and a fifth diode D5. One end of the second resistor R2 is connected to the voltage input terminal of the automatic control sub-circuit 23, and the other end is connected to the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the voltage output terminal of the automatic control sub-circuit 23; the third resistor R3 is connected in parallel with the second resistor R2 to protect the circuit.

[0048] The step-down sub-circuit 25 includes a sixth diode D6 and an inductor L. The anode of the sixth diode D6 is grounded, and its cathode is connected to the voltage output terminal OUT of the step-down chip. One end of the inductor L is connected in parallel with the cathode of the sixth diode D6 to the voltage output terminal OUT of the step-down chip, and the other end is connected to the voltage output terminal of the step-down sub-circuit 25. The re-filter sub-circuit 27 includes several capacitors, which are connected in parallel between the output voltage of the step-down sub-circuit 25 and the ground terminal. Specifically, there are seven capacitors: the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5, the sixth capacitor C6, the seventh capacitor C7, the eighth capacitor C8, and the ninth capacitor C9. Except for the third capacitor C3, which is a non-polar capacitor, the other six capacitors are polarized capacitors. The third capacitor C3 facilitates decoupling of high-frequency voltages, and the polarized capacitors facilitate increasing energy storage capacity.

[0049] Reference Figure 2 The feedback sub-circuit 26 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and a seventh diode D7. One end of the fourth resistor R4 is connected to the voltage input terminal of the feedback sub-circuit 26, and the other end is connected to the fifth resistor R5. The end of the fifth resistor R5 furthest from the fourth resistor R4 is grounded. The voltage input terminal of the temperature detection circuit 4 is connected to the junction of the fourth resistor R4 and the fifth resistor R5, and its voltage output terminal is connected to one end of the sixth resistor R6; the other end of the sixth resistor R6 is grounded.

[0050] Combination Figure 1 In this embodiment, the temperature detection circuit 4 includes a thermistor R0. One end of the thermistor R0 is connected to the voltage input terminal of the temperature detection circuit 4, and the other end is connected to the voltage output terminal of the temperature detection circuit 4. The thermistor R0 can be installed near the power components of the inverter welding machine, such as on the heat sink of the power device IGBT or FRD, to facilitate the sensing of the temperature of the inverter welding machine.

[0051] The seventh resistor R7 and the seventh diode D7 are connected in series to limit the maximum output voltage of the voltage regulator chip 24. Specifically, one end of the seventh resistor R7 is connected to the connection point of the fourth resistor R4 and the fifth resistor R5, and the other end is connected to the anode of the seventh diode D7; the cathode of the seventh diode D7 is connected to the end of the fourth resistor R4 away from the fifth resistor R5.

[0052] The implementation principle of a DC fan power supply circuit for cooling an inverter welding machine according to an embodiment of this application is as follows: When the inverter welding machine is not in overheat protection mode, the welding machine input circuit 1 transmits AC voltage to the control circuit 2, and the rectifier filter sub-circuit 21 converts the AC voltage into DC voltage. The converted DC voltage causes the LED D0 in the power-on indicator sub-circuit 22 to light up, making it easy for the operator to know that there is an input voltage in the control circuit 2. The voltage regulator chip 24 receives the converted DC voltage and regulates the converted DC voltage by changing the duty cycle of the PWM signal, and then outputs the converted DC voltage to the buck sub-circuit 25. After passing through the buck sub-circuit 25, the DC voltage is obtained by the feedback sub-circuit 26, which transmits the output voltage to the voltage feedback pin FB of the voltage regulator chip 24. When the voltage received by the voltage feedback pin FB increases, the voltage regulator chip 24 decreases the duty cycle of the PWM signal, thereby decreasing the output voltage; when the voltage received by the voltage feedback pin decreases, it increases the duty cycle of the PWM signal, thereby increasing the output voltage.

[0053] In addition, due to the influence of the thermistor R0, the resistance value of the thermistor R0 decreases when the temperature of the inverter welding machine rises, which causes the output voltage of the feedback sub-circuit 26 to decrease. This causes the voltage regulator chip 24 to increase the output voltage, which facilitates the increase of the voltage supplied to the DC fan 20, increases the output power of the DC fan 20, increases the speed, and enhances heat dissipation.

[0054] When the inverter welding machine is in overheat protection mode, it stops working, and there is no AC voltage in the inverter welding machine transformer 10, so there is no AC voltage input to the first voltage input terminal CN1 of the control circuit 2. At this time, the fifth diode D5 is forward-biased, and the DC voltage output by the power supply circuit 3 is transmitted to the voltage input pin VIN of the voltage regulator chip 24. After being regulated by the voltage regulator chip 24, the DC voltage is transmitted to the DC fan 20 for use by the DC fan 20.

[0055] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A DC fan power supply circuit for cooling an inverter welding machine, characterized in that: It includes a welding machine input circuit (1) and a control circuit (2); The voltage input terminal of the welding machine input circuit (1) is connected to the voltage output terminal of the welding machine transformer (10), and the voltage output terminal is connected to the first voltage input terminal of the control circuit (2) for transmitting AC voltage to the first voltage input terminal of the control circuit (2) based on the welding machine transformer (10). The voltage output terminal of the control circuit (2) is connected to the voltage input terminal of the DC fan (20) to modulate the AC voltage to the DC working voltage required by the DC fan (20) and then output the DC working voltage to the voltage input terminal of the DC fan (20). The power supply circuit also includes a power supply circuit (3) for supplying power to the welding machine control board; The first voltage output terminal of the power supply circuit (3) is connected to the voltage input terminal of the welding machine control board, and the second voltage output terminal is connected to the second voltage input terminal of the control circuit (2) for transmitting DC voltage to the second voltage input terminal of the control circuit (2). The control circuit (2) is used to receive the DC voltage transmitted from the power supply circuit (3) to the second voltage input terminal when there is no AC voltage at the first voltage input terminal, and modulate the DC voltage to the DC operating voltage required by the DC fan (20); The control circuit (2) is connected to a temperature detection circuit (4); The temperature detection circuit (4) is used to detect the temperature of the welding machine, and its resistance decreases when the temperature of the welding machine increases. The control circuit (2) is used to increase the DC operating voltage when the resistance of the temperature detection circuit (4) decreases, and to decrease the DC operating voltage when the resistance of the temperature detection circuit (4) increases. The control circuit (2) includes a rectifier filter sub-circuit (21), an automatic control sub-circuit (23), a voltage regulator chip (24), and a step-down sub-circuit (25); The voltage input terminal of the rectifier filter sub-circuit (21) is connected to the first voltage input terminal of the control circuit (2), and the voltage output terminal is connected to the voltage input pin of the voltage regulator chip (24). The voltage input terminal of the automatic control sub-circuit (23) is connected to the second voltage input terminal of the control circuit (2), and the voltage output terminal is connected to the voltage input pin of the voltage regulating chip (24). The voltage output pin of the voltage regulating chip (24) is connected to the voltage input terminal of the step-down sub-circuit (25), and the voltage output terminal of the step-down sub-circuit (25) is connected to the voltage output terminal of the control circuit (2).

2. The DC fan power supply circuit for cooling an inverter welding machine according to claim 1, characterized in that: The welding machine input circuit (1) includes a coil wound on the secondary side of the magnetic core of the welding machine transformer (10) and the same-named terminal and the opposite-named terminal of the coil; The rectifier-filter sub-circuit (21) includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first capacitor C1, and a second capacitor C2. The anode of the first diode D1 is connected to the same-name terminal, and the cathode is connected to the voltage output terminal of the rectifier-filter sub-circuit (21). The anode of the second diode D2 is connected to the opposite-name terminal, and the cathode is connected to the voltage output terminal of the rectifier-filter sub-circuit (21). The cathode of the third diode D3 is connected to the same-name terminal, and the anode is grounded. The cathode of the fourth diode D4 is connected to the opposite-name terminal, and the anode is grounded. The positive terminal of the first capacitor C1 is connected to the voltage output terminal of the rectifier-filter sub-circuit (21), and the negative terminal is grounded. The positive terminal of the second capacitor C2 is connected to the voltage output terminal of the rectifier-filter sub-circuit (21), and the negative terminal is grounded. The automatic control sub-circuit (23) includes a second resistor R2, a third resistor R3, and a fifth diode D5; one end of the second resistor R2 is connected to the voltage input terminal of the automatic control sub-circuit (23), and the other end is connected to the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the voltage output terminal of the automatic control sub-circuit (23); the third resistor R3 is connected in parallel with the second resistor R2; The step-down sub-circuit (25) includes a sixth diode D6 and an inductor L; the anode of the sixth diode D6 is grounded, and the cathode is connected to the voltage output terminal of the voltage regulator chip (24); one end of the inductor L is connected in parallel with the cathode of the sixth diode D6 to the voltage output terminal of the voltage regulator chip (24), and the other end is connected to the voltage output terminal of the step-down sub-circuit (25).

3. A DC fan power supply circuit for cooling an inverter welding machine according to claim 1 or 2, characterized in that: The control circuit (2) further includes a feedback sub-circuit (26), the voltage input terminal of the feedback sub-circuit (26) is connected to the voltage output terminal of the step-down sub-circuit (25), and the voltage output terminal is connected to the voltage feedback pin of the voltage regulator chip (24). The feedback sub-circuit (26) is connected to the temperature detection circuit (4); The voltage regulating chip (24) is used to adjust the duty cycle based on the feedback voltage value input from the voltage feedback pin, thereby changing the output voltage.

4. The DC fan power supply circuit for cooling an inverter welding machine according to claim 3, characterized in that: The feedback sub-circuit (26) includes a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6; One end of the fourth resistor R4 is connected to the voltage input terminal of the feedback sub-circuit (26), and the other end is connected to the fifth resistor R5; the end of the fifth resistor R5 away from the fourth resistor R4 is grounded; the voltage input terminal of the temperature detection circuit (4) is connected to the connection node of the fourth resistor R4 and the fifth resistor R5, and the voltage output terminal is connected to one end of the sixth resistor R6; the other end of the sixth resistor R6 is grounded. The temperature detection circuit (4) includes a thermistor R0, one end of which is connected to the voltage input terminal of the temperature detection circuit (4), and the other end is connected to the voltage output terminal of the temperature detection circuit (4).

5. A DC fan power supply circuit for cooling an inverter welding machine according to claim 4, characterized in that: The feedback sub-circuit (26) also includes a seventh resistor R7 and a seventh diode D7; One end of the seventh resistor R7 is connected to the connection node of the fourth resistor R4 and the fifth resistor R5, and the other end is connected to the anode of the seventh diode D7; the cathode of the seventh diode D7 is connected to the end of the fourth resistor R4 away from the fifth resistor R5.

6. A DC fan power supply circuit for cooling an inverter welding machine according to claim 1 or 2, characterized in that: The control circuit (2) further includes a power-on indicator sub-circuit (22) and a re-filtering sub-circuit (27); The voltage input terminal of the power-on indicator sub-circuit (22) is connected to the voltage input pin of the voltage regulator chip (24), and the voltage output terminal is grounded. It is used to output power-on indicator information when there is voltage input at the voltage input pin of the voltage regulator chip (24). The re-filtering sub-circuit (27) is connected to the step-down sub-circuit (25) and is used to re-filter the output voltage of the step-down sub-circuit (25).

7. A DC fan power supply circuit for cooling an inverter welding machine according to claim 6, characterized in that: The power-on indicator sub-circuit (22) includes a first resistor R1 and a light-emitting diode D0; One end of the first resistor R1 is connected to the voltage input pin of the voltage regulating chip (24), and the other end is connected to the anode of the light-emitting diode D0, while the cathode of the light-emitting diode D0 is grounded; The refilter sub-circuit (27) includes a plurality of capacitors, which are connected in parallel between the output voltage of the step-down sub-circuit (25) and the ground terminal.

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