CN115945762A

CN115945762A - Control method of welding power supply and welding power supply

Info

Publication number: CN115945762A
Application number: CN202310030021.7A
Authority: CN
Inventors: 邱光; 刘南; 张明宇; 徐雄; 王巍
Original assignee: Shenzhen Ruiling Industrial Group Co ltd
Current assignee: Shenzhen Ruiling Industrial Group Co ltd
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2023-04-11

Abstract

The invention discloses a control method of a welding power supply and the welding power supply, wherein the control method comprises the following steps: after an input alternating current power supply is rectified by an input rectifying circuit, filtered by a filter capacitor, inverted by an inverter circuit and rectified by an output rectifying circuit in sequence, adjustable direct current is obtained and then output; receiving a given current signal, and adjusting the inversion power of an inverter circuit according to the given current signal so as to control the magnitude of output direct current; detecting a first current signal acquired by a filter capacitor and adding the first current signal to the given current signal; and adjusting the inversion power of the inverter circuit according to the superposed signal so that the output direct current of the output rectification circuit can be correspondingly changed along with the current change of the first current signal collected by the filter capacitor. The technical scheme of the invention solves the heating problem of the filter capacitor on the premise of ensuring the output power of the welding power supply without increasing the capacity of the filter capacitor.

Description

Control method of welding power supply and welding power supply

Technical Field

The invention relates to the technical field of welding machines, in particular to a control method of a welding power supply and the welding power supply.

Background

The welding power supply is typically a high power switching power supply of several kilowatts to several tens of kilowatts. In practical application of the welding power supply, the welding power supply needs to adopt a high-voltage electrolytic capacitor for filtering after passing through an input rectifying circuit, so as to ensure stable power supply of the inverter.

Therefore, the capacity of the filter capacitor depends on the output power of the welding power supply, generally, the larger the output power is, the larger the capacity of the filter capacitor is needed, otherwise, the high-voltage electrolytic capacitor can generate heat seriously due to the overlarge ripple current of charging and discharging, and the high-voltage electrolytic capacitor can fail quickly.

At present, the main method for solving the heating problem of the filter capacitor is to increase the capacity of the filter capacitor by connecting a plurality of high-voltage electrolytic capacitors in parallel in a main circuit of a welding power supply. However, the solution not only increases the total volume of the capacitor in the main circuit, which is not beneficial to realizing miniaturization of the welding power supply product, but also increases the cost of the welding power supply product.

Disclosure of Invention

The invention mainly aims to provide a control method of a welding power supply, aiming at solving the heating problem of a filter capacitor on the premise of ensuring the output power of the welding power supply and not increasing the capacity of the filter capacitor.

In order to achieve the above object, the present invention provides a control method of a welding power supply, including:

after an input alternating current power supply is rectified by an input rectifying circuit, filtered by a filter capacitor, inverted by an inverter circuit and rectified by an output rectifying circuit in sequence, adjustable direct current is obtained and then output;

receiving a given current signal, and adjusting the inversion power of an inverter circuit according to the given current signal so as to control the magnitude of output direct current;

detecting a first current signal acquired by a filter capacitor and adding the first current signal to the given current signal;

and adjusting the inversion power of the inversion circuit according to the superposed signals so that the output direct current of the output rectification circuit is correspondingly changed along with the current change of the first current signal acquired by the filter capacitor.

Optionally, after the filter capacitor collects the first current signal, the filter capacitor correspondingly charges and discharges following the pulsation of the collected first current signal to output the pulsating first current signal;

the step of detecting the first current signal collected by the filter capacitor and adding the first current signal to the given current signal is specifically as follows: and detecting a pulsating first current signal output by the filter capacitor, and adding the pulsating first current signal to the given current signal so that the given current signal pulsates along with the pulsating first current signal.

Optionally, the step of adjusting the inverter power of the inverter circuit according to the superimposed signal to enable the output dc of the output rectification circuit to follow the current change of the first current signal collected by the filter capacitor to change correspondingly includes:

determining an output duty ratio according to the superposed signals, and outputting pulse width modulation signals corresponding to the duty ratio;

and isolating the pulse width modulation signal and outputting the pulse width modulation signal to an inverter circuit so as to adjust the inverter power of the inverter circuit, so that the output direct current of the output rectifying circuit corresponds to the target current corresponding to the given current signal, and the output direct current of the output rectifying circuit is correspondingly changed along with the current change of the first current signal acquired by the filter capacitor.

Optionally, the control method of the welding power supply further includes:

detecting a second current signal output by the inverter circuit, outputting a corresponding second current detection signal, and determining a current value output by the inverter circuit according to the received second current detection signal;

and comparing the current value output by the inverter circuit with a given current value corresponding to a given voltage signal, and controlling the output current of the inverter circuit to correspond to the target current corresponding to the given voltage signal according to the comparison result.

In addition, to achieve the above object, another aspect of the present application further provides a welding power supply, including:

the input rectification circuit is used for rectifying an input alternating current power supply into a direct current power supply and then outputting the direct current power supply;

the filter capacitor is used for filtering ripple current in the direct current power supply;

the inverter circuit is used for inverting and reducing the direct current output by the input rectifying circuit into alternating square wave current;

the output rectifying circuit is used for rectifying the alternating square wave current output by the inverter circuit into adjustable direct current;

the current detection circuit is used for detecting a first current signal acquired by the filter capacitor and superposing the first current signal to a given current signal;

the control circuit is used for receiving a given current signal and adjusting the inversion power of the inversion circuit according to the given current signal so as to control the magnitude of the output direct current; and the inverter circuit is also used for adjusting the inverter power of the inverter circuit according to the superposed signal so as to enable the output direct current of the output rectifying circuit to follow the current change of the first current signal acquired by the filter capacitor to be correspondingly changed.

Optionally, a power input end of the input rectification circuit is used for accessing an alternating current power supply, and a power output end of the input rectification circuit is connected with a power input end of the inverter circuit through the filter capacitor; the power output end of the inverter circuit is connected with the power input end of the output rectifying circuit; the power output end of the output rectifying circuit is used for outputting adjustable direct current;

the voltage detection input end of the current detection circuit is connected with the signal output end of the filter capacitor, the signal output end of the current detection circuit is connected with the first signal input end of the control circuit, the signal output end of the control circuit is connected with the signal input end of the inverter circuit, and the control end of the control circuit is respectively connected with the controlled end of the current detection circuit and the controlled end of the inverter circuit.

Optionally, the current detection circuit includes:

the current transformer is provided with a first side and a second side, wherein the first side is a voltage detection input end of the current transformer, and the second side is a signal output end of the current transformer;

the current transformer is used for detecting a first current signal acquired by the filter capacitor;

a signal input end of the given current unit is connected with a signal output end of the current transformer, a signal output end of the given current unit is connected with a first signal input end of the control circuit, and a controlled end of the given current unit is connected with a control end of the control circuit;

the given current unit is used for outputting the given current signal to be superposed on the first current signal and sending the superposed signal to the control circuit.

Optionally, the control circuit includes a PWM controller and an isolation driving circuit; wherein the content of the first and second substances,

a first signal input end of the PWM controller is connected with a common end of the given current unit and the current transformer;

the signal output end of the PWM controller is connected with the controlled end of the isolation driving circuit, the input end of the isolation driving circuit is connected with a direct-current power supply, and the output end of the isolation driving circuit is connected with the inverter circuit;

the PWM controller is used for generating a pulse width modulation signal according to the superposed signal;

and the isolation driving circuit is used for isolating the pulse width modulation signal and outputting the isolated pulse width modulation signal to the inverter circuit.

Optionally, the isolation driving circuit includes a first switch, a second switch and an isolation transformer; wherein the content of the first and second substances,

the controlled end of the first switch and the controlled end of the second switch are respectively connected with the control end of the PWM controller, and the signal output end of the first switch and the signal output end of the second switch are respectively connected with the signal input end of the isolation transformer;

the output end of the isolation transformer is connected with the inverter circuit;

the first switch and the second switch are used for converting the pulse width modulation signal into a pulse width modulation driving signal and outputting the pulse width modulation driving signal to the isolation transformer;

and the isolation transformer is used for converting and isolating the pulse width modulation driving signal and outputting the pulse width modulation driving signal to the inverter circuit.

Optionally, the output rectification circuit includes:

the current detection input end of the shunt is connected with the power supply output end of the inverter circuit, and the signal output end of the shunt is connected with the second signal input end of the control circuit;

the current divider is used for detecting a second current signal output by the inverter circuit, generating a corresponding second current detection signal and outputting the second current detection signal to the control circuit.

The technical scheme of the invention provides a control method of a welding power supply and the welding power supply, wherein the control method comprises the following steps: after an input alternating current power supply is rectified by an input rectifying circuit, filtered by a filter capacitor, inverted by an inverter circuit and rectified by an output rectifying circuit in sequence, adjustable direct current is obtained and then output; receiving a given current signal, and adjusting the inversion power of an inverter circuit according to the given current signal so as to control the magnitude of output direct current; detecting a first current signal acquired by a filter capacitor and adding the first current signal to the given current signal; and adjusting the inversion power of the inverter circuit according to the superposed signal so that the output direct current of the output rectification circuit can be correspondingly changed along with the current change of the first current signal collected by the filter capacitor. The technical scheme of the invention solves the heating problem of the filter capacitor on the premise of ensuring the output power of the welding power supply without increasing the capacity of the filter capacitor.

Drawings

In order to more clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the embodiments or technical solutions of the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic flow chart diagram illustrating a method for controlling a welding power supply in accordance with one embodiment of the present invention;

FIG. 2 is a schematic flow chart diagram illustrating another exemplary method of controlling a welding power supply in accordance with the present invention;

FIG. 3 is a schematic flow chart diagram illustrating a method for controlling a welding power supply in accordance with another embodiment of the present invention;

FIG. 4 is a schematic flow chart illustrating a method for controlling a welding power supply according to yet another embodiment of the present invention;

FIG. 5 is a schematic circuit diagram of a welding power supply according to an embodiment of the invention;

FIG. 6 is a functional block diagram of a welding power supply according to an embodiment of the present invention;

FIG. 7 is a functional block diagram of a welding power supply according to another embodiment of the present invention;

FIG. 8 is a functional block diagram of a welding power supply according to another embodiment of the present invention;

FIG. 9 is a functional block diagram of a welding power supply according to another embodiment of the present invention.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				10	Input rectification circuit	20	Filter capacitor
30	Inverter circuit	40	Output rectifying circuit
				41	Flow divider	50	Current detection circuit
51	Current transformer	52	Given current unit
				60	Control circuit	61	PWM controller
62	Isolation driving circuit	621	First switch
				622	Second switch	623	Isolation transformer

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.

It should be noted that, if the present invention relates to directional indications (such as up, down, left, right, front, back, 8230; \8230;), the directional indications are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture, and if the specific posture is changed, the directional indications are correspondingly changed.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, if the meaning of "and/or" and/or "appears throughout, the meaning includes three parallel schemes, for example," A and/or B "includes scheme A, or scheme B, or a scheme satisfying both schemes A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

It will be appreciated that welding power supplies are typically high power switching power supplies of several kilowatts to tens of kilowatts. In practical application of the welding power supply, the welding power supply needs to be filtered by a high-voltage electrolytic capacitor after passing through the input rectifying circuit 10, so as to ensure stable power supply of the inverter.

Therefore, the capacity of the filter capacitor 20 depends on the output power of the welding power supply, and generally, the larger the output power is, the larger the capacity of the filter capacitor 20 is needed, otherwise, the high-voltage electrolytic capacitor may generate heat seriously due to the excessive charging and discharging ripple current, resulting in rapid failure.

At present, the main method for solving the heating problem of the filter capacitor 20 is to increase the capacity of the filter capacitor 20 by connecting a plurality of high-voltage electrolytic capacitors in parallel in the main circuit of the welding power supply. However, the solution not only increases the total volume of the capacitor in the main circuit, which is not beneficial to realizing miniaturization of the welding power supply product, but also increases the cost of the welding power supply product.

Therefore, the invention also provides a control method of the welding power supply, which aims to solve the heating problem of the filter capacitor 20 on the premise of ensuring the output power of the welding power supply and not increasing the capacity of the filter capacitor 20.

Referring to fig. 1 to 4, in an embodiment of the present invention, a control method of a welding power supply includes:

after an alternating current input power supply is rectified by an input rectifying circuit 10, filtered by a filter capacitor 20, inverted by an inverter circuit 30 and rectified by an output rectifying circuit 40 in sequence, adjustable direct current is obtained and then output;

receiving the given current signal, and adjusting the inversion power of the inverter circuit 30 according to the given current signal to control the magnitude of the output direct current;

detecting a first current signal collected by the filter capacitor 20 and adding the first current signal to the given current signal;

the inversion power of the inverter circuit 30 is adjusted according to the superimposed signal, so that the output dc of the output rectifying circuit 40 follows the current variation of the first current signal collected by the filter capacitor 20.

Specifically, in the present embodiment, the welding power supply includes an input rectification circuit 10, a filter capacitor 20, an inverter circuit 30, an output rectification circuit 40, a current detection circuit 50, and a control circuit 60; the power input end of the input rectification circuit 10 is used for accessing an alternating current power supply, the power output end of the input rectification circuit 10 is connected with the power input end of the inverter circuit 30 through the filter capacitor 20, the power output end of the inverter circuit 30 is connected with the power input end of the output rectification circuit 40, and the power output end of the output rectification circuit 40 is used for outputting adjustable direct current. A voltage detection input terminal of the current detection circuit 50 is connected to a signal output terminal of the filter capacitor 20, a signal output terminal of the current detection circuit 50 is connected to a first signal input terminal of the control circuit 60, a signal output terminal of the control circuit 60 is connected to a signal input terminal of the inverter circuit 30, and a control terminal of the control circuit 60 is connected to a controlled terminal of the current detection circuit 50 and a controlled terminal of the inverter circuit 30, respectively.

It should be understood that the input rectification circuit 10 is used for rectifying an ac power supply into a dc power supply and then outputting the dc power supply to the inverter circuit 30; the filter capacitor 20 is used for filtering ripple current in the dc power supply; the inverter circuit 30 is used for inverting and reducing the direct current output by the input rectifying circuit 10 into alternating square wave current; the output rectifying circuit 40 is used for rectifying the received alternating square wave current into adjustable direct current and outputting the adjustable direct current to a load; the current detection circuit 50 is configured to detect a first current signal collected by the filter capacitor 20 and add the first current signal to a given current signal; the control circuit 60 is configured to receive the given current signal, and adjust the inverter power of the inverter circuit 30 according to the given current signal to control the magnitude of the output dc, and further adjust the inverter power of the inverter circuit 30 according to the superimposed signal, so that the output dc of the output rectifying circuit 40 varies correspondingly with the current variation of the first current signal collected by the filter capacitor 20.

Specifically, in the practical application of the welding power supply, the input ac power supply is rectified by the input rectifying circuit 10, filtered by the filter capacitor 20, inverted by the inverter circuit 30, and rectified by the output rectifying circuit 40 in sequence, so as to obtain an adjustable dc, and then output the dc to the load. Meanwhile, the first signal input terminal of the control circuit 60 receives the first current signal output by the current detection circuit 50. The control circuit 60 superimposes the first current signal on the given current signal, and controls the controlled terminal of the inverter circuit 30 through the control terminal according to the superimposed signal to adjust the inverter power of the inverter circuit 30, so that the output current of the inverter circuit 30 corresponds to the target current corresponding to the given current signal.

On the basis, the voltage detection input terminal of the current detection circuit 50 detects the first current signal collected by the filter capacitor 20 in real time, and superimposes the first current signal on the given current signal through the signal output terminal. After the signals are superimposed, the signal output terminal of the current detection circuit 50 sends the superimposed signals to the first signal input terminal of the control circuit 60. The control circuit 60, upon receiving the signal, invokes the stored algorithm to determine the duty cycle to be output and generates the corresponding pulse width modulated signal based on the determined duty cycle. After the pwm signal is driven and isolated, the control circuit 60 further outputs the adjusted pwm signal to the signal input terminal of the inverter circuit 30 through the signal output terminal, and further adjusts the inverter power of the inverter circuit 30, so that the output dc of the output rectifying circuit 40 is varied with the current variation of the first current signal collected by the filter capacitor 20. Therefore, through the synchronous change, a large current is output when the voltage of the alternating current power supply is high, and a small current is output when the voltage of the alternating current power supply is low, so that the ripple current of the filter capacitor 20 is reduced, the working temperature of the filter capacitor is reduced under the condition that the capacity of the filter capacitor 20 is not increased, and the service life of the filter capacitor is prolonged.

The technical scheme of the invention provides a control method of a welding power supply, which comprises the following steps: after an input alternating current power supply is rectified by an input rectifying circuit 10, filtered by a filter capacitor 20, inverted by an inverter circuit 30 and rectified by an output rectifying circuit 40 in sequence, adjustable direct current is obtained and then output; receiving a given current signal, and adjusting the inversion power of the inverter circuit 30 according to the given current signal to control the magnitude of the output direct current; detecting a first current signal collected by the filter capacitor 20 and adding the first current signal to the given current signal; the inversion power of the inverter circuit 30 is adjusted according to the superimposed signal, so that the output dc of the output rectifying circuit 40 correspondingly changes with the current change of the first current signal collected by the filter capacitor 20. The technical scheme of the invention solves the heating problem of the filter capacitor 20 on the premise of ensuring the output power of the welding power supply without increasing the capacity of the filter capacitor 20.

Referring to fig. 2, in an embodiment of the present invention, after the filter capacitor 20 collects the first current signal, the filter capacitor is charged and discharged correspondingly along with the pulsation of the collected first current signal to output a pulsating first current signal;

the step of detecting the first current signal collected by the filter capacitor 20 and adding the first current signal to the given current signal specifically includes: the pulsating first current signal output from the filter capacitor 20 is detected and added to the given current signal so that the given current signal pulsates following the pulsating first current signal.

Specifically, in the present embodiment, after the ac power source is rectified into the dc power source through the input rectification circuit 10, the filter capacitor 20 collects a first current signal in the dc power source, and charges and discharges along with the pulsation of the collected first current signal to output a corresponding pulsating first current signal. Meanwhile, the current detection circuit 50 detects the pulsating first current signal output from the filter capacitor 20 in real time, and superimposes the detected signal on the given current signal so that the given current signal pulsates following the pulsating first current signal.

Referring to fig. 3, in an embodiment of the present invention, the step of adjusting the inverting power of the inverting circuit 30 according to the superimposed signal so that the output dc of the output rectifying circuit 40 follows the current variation of the first current signal collected by the filter capacitor 20 to a corresponding variation includes:

determining an output duty ratio according to the superposed signals, and outputting a pulse width modulation signal corresponding to the duty ratio;

the pulse width modulation signal is isolated and then output to the inverter circuit 30 to adjust the inverter power of the inverter circuit 30, so that the output direct current of the output rectifying circuit 40 corresponds to the target current corresponding to the given current signal, and the output direct current of the output rectifying circuit 40 correspondingly changes along with the current change of the first current signal acquired by the filter capacitor 20.

Specifically, as can be seen from the above embodiment, the superimposed signal is output to the first signal input terminal of the control circuit 60 through the signal output terminal of the current detection circuit 50. After receiving the superimposed signal, the PWM controller 61 in the control circuit 60 invokes a stored algorithm to determine a duty ratio to be output, and generates a corresponding pulse width modulation signal according to the determined duty ratio, and then outputs the signal to the signal input terminal of the isolation driving circuit 62 in the control circuit 60 through the signal output terminal of the PWM controller 61. After the isolation driving circuit 62 drives and isolates the above signals, the pulse width modulation driving signal is output to the signal input end of the inverter circuit 30 through the signal output end thereof, and then the inverter power of the inverter circuit 30 is adjusted, so that when the output direct current of the output rectifying circuit 40 corresponds to the target current corresponding to the given current signal, the output direct current of the output rectifying circuit 40 also changes correspondingly along with the current change of the first current signal acquired by the filter capacitor 20, and thus the ripple current of the filter capacitor 20 is reduced.

Referring to fig. 4, in an embodiment of the present invention, the control method of the welding power supply further includes:

detecting a second current signal output by the inverter circuit 30, outputting a corresponding second current detection signal, and determining a current value output by the inverter circuit 30 according to the received second current detection signal;

the current value output by the inverter circuit 30 is compared with a given current value corresponding to a given voltage signal, and the output current of the inverter circuit 30 is controlled to correspond to the target current corresponding to the given voltage signal according to the comparison result.

It can be understood that, in order to further verify whether the output dc of the output rectifying circuit 40 follows the current change of the first current signal collected by the filter capacitor 20, the output rectifying circuit 40 according to the present invention includes the current divider 41. The current detection input end of the shunt 41 is connected with the power output end of the inverter circuit 30, the signal output end of the shunt 41 is connected with the second signal input end of the control circuit 60, and the controlled end of the shunt 41 is connected with the control end of the control circuit 60.

In this manner, in practical application of the welding power supply, the shunt 41 detects the second current signal output by the inverter circuit 30, and outputs the second current detection signal to the second signal input terminal of the control circuit 60 through the signal output terminal. The control circuit 60 calls the stored algorithm to calculate the current value output by the inverter circuit 30 after receiving the second current detection signal.

Further, the control circuit 60 compares the current value output from the inverter circuit 30 with a predetermined current value corresponding to a predetermined current signal. When the current value output from the inverter circuit 30 is higher or lower than a given current value, the control circuit 60 determines the duty ratio to be output again, and generates a new pulse width modulation signal according to the duty ratio determined twice. After the new pwm signal is driven and isolated, the control circuit 60 further outputs the new pwm signal to the signal input terminal of the inverter circuit 30 through the signal output terminal to adjust the inverter power of the inverter circuit 30 until the output current of the inverter circuit 30 corresponds to the target current corresponding to the given current signal.

The present application further provides a welding power supply, where the control method of the welding power supply is used for the welding power supply, and the specific structure of the control method of the welding power supply refers to the above embodiments.

Referring to fig. 5 and 6, in an embodiment of the invention, the welding power supply comprises:

an input rectifying circuit 10 for rectifying an input ac power supply into a dc power supply and outputting the dc power supply;

the filter capacitor 20 is used for filtering ripple current in the direct current power supply;

the inverter circuit 30 is used for inverting and reducing the direct current output by the input rectifying circuit 10 into alternating square wave current;

an output rectifying circuit 40 for rectifying the ac square wave current output by the inverter circuit 30 into an adjustable dc voltage;

a current detection circuit 50, configured to detect a first current signal collected by the filter capacitor 20, and add the first current signal to a given current signal;

the control circuit 60 is configured to receive a given current signal, and adjust the inverter power of the inverter circuit 30 according to the given current signal to control the magnitude of the output direct current; and is further configured to adjust the inverting power of the inverting circuit 30 according to the superimposed signal, so that the output dc of the output rectifying circuit 40 follows the current variation of the first current signal acquired by the filter capacitor 20.

Specifically, in practical application of the welding power supply, the input ac power supply is rectified by the input rectification circuit 10, filtered by the filter capacitor 20, inverted by the inverter circuit 30, and rectified by the output rectification circuit 40 in sequence to obtain an adjustable dc, and then the dc is output to the load. Meanwhile, the first signal input terminal of the control circuit 60 receives the first current signal output by the current detection circuit 50. The control circuit 60 superimposes the first current signal on the given current signal, and controls the controlled terminal of the inverter circuit 30 through the control terminal according to the superimposed signal to adjust the inverter power of the inverter circuit 30, so that the output current of the inverter circuit 30 corresponds to the target current corresponding to the given current signal.

On the basis, the voltage detection input terminal of the current detection circuit 50 detects the first current signal collected by the filter capacitor 20 in real time, and superimposes the first current signal on the given current signal through the signal output terminal. After the signals are superimposed, the signal output terminal of the current detection circuit 50 sends the superimposed signals to the first signal input terminal of the control circuit 60. The control circuit 60, upon receiving the signal, invokes the stored algorithm to determine the duty cycle to be output and generates a corresponding pulse width modulated signal based on the determined duty cycle. After the pwm signal is driven and isolated, the control circuit 60 further outputs the adjusted pwm signal to the signal input terminal of the inverter circuit 30 through the signal output terminal, and further adjusts the inverter power of the inverter circuit 30, so that the output dc of the output rectifying circuit 40 is varied with the current variation of the first current signal collected by the filter capacitor 20. Therefore, through the synchronous change, a large current is output when the voltage of the alternating current power supply is high, and a small current is output when the voltage of the alternating current power supply is low, so that the ripple current of the filter capacitor 20 is reduced, the working temperature of the filter capacitor 20 is reduced under the condition that the capacity of the filter capacitor 20 is not increased, and the service life of the filter capacitor 20 is prolonged.

Referring to fig. 5 and 6, in an embodiment of the present invention, a power input end of the input rectification circuit 10 is used for accessing an ac power supply, and a power output end of the input rectification circuit 10 is connected to a power input end of the inverter circuit 30 through the filter capacitor 20; the power output end of the inverter circuit 30 is connected with the power input end of the output rectifying circuit 40; the power output end of the output rectifying circuit 40 is used for outputting adjustable direct current;

the voltage detection input end of the current detection circuit 50 is connected with the signal output end of the filter capacitor 20, the signal output end of the current detection circuit 50 is connected with the first signal input end of the control circuit 60, the signal output end of the control circuit 60 is connected with the signal input end of the inverter circuit 30, and the control end of the control circuit 60 is respectively connected with the controlled end of the current detection circuit 50 and the controlled end of the inverter circuit 30.

Specifically, the input rectification circuit 10 includes a rectification bridge DB1, the rectification bridge DB1 having a first end, a second end, a third end, and a fourth end; the first end is connected to the positive terminal of the input ac power supply, the second end is connected to the negative terminal of the input ac power supply, the third end is connected to the positive terminal of the power input terminal of the inverter circuit 30 through the filter capacitor 20, and the fourth end is connected to the negative terminal of the power input terminal of the inverter circuit 30 through the filter capacitor 20. Alternatively, the model of the rectifier bridge DB1 is not particularly limited herein, and may be set as needed.

Further, the inverter circuit 30 includes a first MOS transistor Q1 and a second MOS transistor Q2; the first end of first MOS pipe Q1 is connected with rectifier bridge DB 1's third end, and the second end of first MOS pipe Q1 is connected with second MOS pipe Q2's first end, and second MOS pipe Q2's second end is connected with rectifier bridge DB 1's fourth end. The inverter circuit 30 further includes a second capacitor C2, a third capacitor C3, a second resistor R2, a third resistor R3, and a main inverter T1; a first end of the second capacitor C2 is connected to a third end of the rectifier bridge DB1 and a first end of the first MOS transistor Q1, a third end of the first MOS transistor Q1 is connected to a first end of the second resistor R2, a second end of the second resistor R2 is connected to a first end of a first primary side of the main inverter T1, and a second end of the first primary side of the main inverter T1 is connected to a second end of the second capacitor C2; a first end of the third capacitor C3 is connected to the third end of the rectifier bridge DB1 and the second end of the first primary side of the main inverter T1, the first end of the first primary side of the main inverter T1 is connected to the first end of the second MOS transistor Q2, the third end of the second MOS transistor Q2 is connected to the first end of the third resistor R3, and the second end of the third resistor R3 is connected to the second end of the third capacitor C3. Further, a third terminal of the second secondary side of the main inverter T1 is connected to a positive terminal of the power input terminals of the output rectifier circuit 40, and a fourth terminal of the second secondary side of the main inverter T1 is connected to a negative terminal of the power input terminals of the output rectifier circuit 40.

It should be understood that the output rectifying circuit 40 includes a first diode D1, and the first diode D1 is implemented by a fast recovery rectifying diode. The first end and the second end of the first diode D1 are both connected with the third end of the second secondary side of the main inverter T1, and the third end of the first diode D2 is connected with the power input end of the output load.

Further, the current detection circuit 50 includes a current transformer 51 (T2 shown in fig. 4), a first resistor R1, and a given current unit 52; the current transformer 51 has a first side and a second side, a first end of the first side is connected to the third end of the rectifier bridge DB1, and a second end of the first side is connected to the first end of the first capacitor C1; the third end of the second secondary side is connected with the first end of the first resistor R1 and the signal input end of the given current unit 52 respectively, and the fourth end of the second secondary side is connected with the second end of the first resistor R1; the signal output of the given current cell 52 is connected to a first signal input of a control circuit 60.

It is understood that the control circuit 60 includes a PWM controller 61 and an isolation drive circuit 62; the PWM controller 61 is implemented by a control chip. The control chip comprises a first input pin PA0, a first output pin PWMA and a second output pin PWMB, wherein the first input pin PA0 is connected with the signal output end of the given current unit 52, and the first output pin PWMA and the second output pin PWMB are both connected with the signal input end of the isolation driving circuit 62; the isolation driving circuit 62 includes a first triode Q3, a second triode Q4, a third triode Q5, a fourth triode Q6 and a driving transformer T3; a first end of the first triode Q3 and a first end of the second triode Q4 are both connected with the first output pin PWMA, and a third end of the first triode Q3 and a second end of the second triode Q4 are respectively connected with a first end of a first primary side of the driving transformer T3; a first end of the third triode Q5 and a first end of the fourth triode Q6 are both connected with the second output pin PWMB, and a third end of the third triode Q5 and a second end of the fourth triode Q6 are respectively connected with a second end of the primary side of the driving transformer T3; the driving transformer T3 further has a second secondary side and a third secondary side which are independent of each other with respect to the first primary side, a first end of the second secondary side is connected to a second end of the second resistor R2, a second end of the second secondary side is connected to a first end of the main inverter T1 at the first time, a first end of the third secondary side is connected to a second end of the third resistor R3, and a second end of the third secondary side is connected to a second end of the third capacitor C3 and a first end of the second MOS transistor Q2, respectively.

Referring to fig. 7, in an embodiment of the present invention, the current detection circuit 50 includes:

a current transformer 51, wherein the current transformer 51 has a first side and a second side, the first side is a voltage detection input end of the current transformer 51, and the second side is a signal output end of the current transformer 51;

the current transformer 51 is configured to detect a first current signal collected by the filter capacitor 20;

a given current unit 52, a signal input terminal of the given current unit 52 is connected with a signal output terminal of the current transformer 51, a signal output terminal of the given current unit 52 is connected with a first signal input terminal of the control circuit 60, and a controlled terminal of the given current unit 52 is connected with a control terminal of the control circuit 60;

the given current unit 52 is configured to output the given current signal to be superimposed on the first current signal, and send the superimposed signal to the control circuit 60.

Specifically, in practical application of the welding power supply, the voltage detection input terminal of the current transformer 51 detects the first current signal collected by the filter capacitor 20, and outputs a corresponding pulsating first current signal to the signal input terminal of the given current unit 52 through the signal output terminal, so as to superimpose the given current signal output by the given current unit 52. The superimposed signal is further output to a first signal input terminal of the control circuit 60 through a signal output terminal of the given current unit 52, so that the control circuit 60 determines a duty ratio to be output after receiving the signal to control the inverter power of the inverter circuit 30.

Referring to fig. 7, in an embodiment of the present invention, the control circuit 60 includes a PWM controller 61 and an isolation driving circuit 62; wherein the content of the first and second substances,

a first signal input terminal of the PWM controller 61 is connected to a common terminal of the given current cell 52 and the current transformer 51;

the signal output end of the PWM controller 61 is connected to the controlled end of the isolation driving circuit 62, the input end of the isolation driving circuit 62 is connected to a dc power supply, and the output end of the isolation driving circuit 62 is connected to the inverter circuit 30;

a PWM controller 61 for generating a pulse width modulation signal from the superimposed signal;

and the isolation driving circuit 62 is configured to convert and isolate the pulse width modulation signal and output the pulse width modulation signal to the inverter circuit 30.

Specifically, in practical application of the welding power supply, the current detection circuit 50 superimposes the detected first current signal on the given current signal, and outputs the superimposed signal to the first signal input terminal of the PWM controller 61 in the control circuit 60 through the signal output terminal. The PWM controller 61 calls a stored algorithm according to the received superimposed signal, determines a duty ratio to be output, and outputs a corresponding pulse width modulation signal to the isolation driving circuit 62 through a signal output terminal according to the determined duty ratio. The isolation driving circuit 62 converts the pwm signal into a pwm driving signal, and outputs the pwm driving signal to the inverter circuit 30 through the output terminal after isolation, so as to adjust the inverter power of the inverter circuit 30, so that the output dc of the output rectifying circuit 40 follows the current change of the first current signal collected by the filter capacitor 20.

Referring to fig. 8, in an embodiment of the present invention, the isolation driving circuit 62 includes a first switch 621, a second switch 622, and an isolation transformer 623; wherein the content of the first and second substances,

a controlled end of the first switch 621 and a controlled end of the second switch 622 are respectively connected to a control end of the PWM controller 61, and a signal output end of the first switch 621 and a signal output end of the second switch 622 are respectively connected to a signal input end of the isolation transformer 623;

the output end of the isolation transformer 623 is connected with the inverter circuit 30;

the first switch 621 and the second switch 622 are both configured to convert the pulse width modulation signal into a pulse width modulation driving signal and output the pulse width modulation driving signal to the isolation transformer 623;

the isolation transformer 623 is configured to isolate the pulse width modulation driving signal and output the isolated pulse width modulation driving signal to the inverter circuit 30.

It is understood that the first switch 621 and the PWM controller 61 form a first loop, and the second switch 622 and the PWM controller 61 form a second loop. Specifically, as can be seen from the above embodiment, the PWM controller 61 determines the output duty ratio after receiving the superimposed signal, and outputs the corresponding first pulse width modulation signal or second pulse width modulation signal to the controlled terminals of the first switch 621 and the second switch 622 through the control terminal according to the determined output duty ratio, so as to selectively open the first loop or the second loop. Thus, when the first loop is turned on, the first switch 621 converts the first pwm signal into a first pwm driving signal, and outputs the first pwm driving signal to the signal input terminal of the isolation transformer 623 through the signal output terminal. Similarly, when the second circuit is turned on, the second switch 622 converts the second pwm signal into a second pwm driving signal, and outputs the second pwm driving signal to the signal input terminal of the isolation transformer 623 through the signal output terminal.

Further, the isolation transformer 623 isolates the first pwm driving signal and the second pwm driving signal respectively and outputs the isolated signals to the inverter circuit 30. The inverter circuit 30 continuously adjusts its own inverter power according to the difference of the received signals, so that the output dc of the output rectifier circuit 40 follows the current variation of the first current signal collected by the filter capacitor 20.

Referring to fig. 9, in an embodiment of the present invention, the output rectifying circuit 40 includes:

a current detection input terminal of the current divider 41 is connected to the power output terminal of the inverter circuit 30, and a signal output terminal of the current divider 41 is connected to a second signal input terminal of the control circuit 60;

the current divider 41 is configured to detect a second current signal output by the inverter circuit 30, generate a corresponding second current detection signal, and output the second current detection signal to the control circuit 60.

Specifically, the current detection terminal of the shunt 41 is connected to the power output terminal of the inverter circuit 30, the signal output terminal of the shunt 41 is connected to the second signal input terminal of the control circuit 60, and the controlled terminal of the power detection circuit is connected to the control terminal of the control circuit 60.

In this manner, in practical application of the welding power supply, the current divider 41 detects the second current signal output by the inverter circuit 30, and outputs the second current detection signal to the second signal input terminal of the control circuit 60 through the signal output terminal. The control circuit 60 calls the stored algorithm to calculate the current value output by the inverter circuit 30 after receiving the second current detection signal.

Further, the control circuit 60 compares the current value output from the inverter circuit 30 with a predetermined current value corresponding to a predetermined current signal. When the current value output from the inverter circuit 30 is higher or lower than the given current value, the control circuit 60 determines the duty ratio to be output again, and generates a new pulse width modulation signal according to the duty ratio determined twice. After the new pwm signal is driven and isolated, the control circuit 60 further outputs the new pwm signal to the signal input terminal of the inverter circuit 30 through the signal output terminal to adjust the inverter power of the inverter circuit 30 until the output current of the inverter circuit 30 corresponds to the target current corresponding to the given current signal.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A method of controlling a welding power supply, comprising:

2. The control method of the welding power supply according to claim 1, wherein the filter capacitor collects the first current signal and then charges and discharges in response to a ripple of the collected first current signal to output a ripple first current signal;

the step of detecting the first current signal collected by the filter capacitor and adding the first current signal to the given current signal is specifically as follows: and detecting a pulsating first current signal output by the filter capacitor and adding the pulsating first current signal to the given current signal so that the given current signal is pulsed along with the pulsating first current signal.

3. The method of claim 1, wherein the step of adjusting the inverter power of the inverter circuit according to the superimposed signal to make the output dc of the output rectifier circuit follow the current variation of the first current signal collected by the filter capacitor comprises:

4. The method of controlling a welding power supply of claim 1, further comprising:

5. A welding power supply, comprising:

the input rectifying circuit is used for rectifying an input alternating current power supply into a direct current power supply and then outputting the direct current power supply;

6. The welding power supply of claim 5, wherein the power input of the input rectifying circuit is configured to be connected to an ac power source, and the power output of the input rectifying circuit is connected to the power input of the inverter circuit via the filter capacitor; the power output end of the inverter circuit is connected with the power input end of the output rectifying circuit; the power output end of the output rectifying circuit is used for outputting adjustable direct current;

7. The welding power supply of claim 5, wherein the current detection circuit comprises:

8. The welding power supply of claim 5, wherein the control circuitry comprises a PWM controller and isolated drive circuitry; wherein the content of the first and second substances,

9. The welding power supply of claim 8, wherein the isolation drive circuit comprises a first switch, a second switch, and an isolation transformer; wherein the content of the first and second substances,

10. The welding power supply of claim 5, wherein the output rectification circuit comprises:

the shunt is used for detecting a second current signal output by the inverter circuit, generating a corresponding second current detection signal and outputting the second current detection signal to the control circuit.