Power supply circuit and welding machine

Abstract

A power supply circuit and a welding machine belong to the technical field of power supply. A first conversion circuit converts input alternating current to output a first direct current; an inverter circuit inverts the first direct current according to a first drive signal to output a first alternating current; a second conversion circuit converts the first alternating current to output a second direct current; a first detection circuit detects the second direct current to output a first current sampling signal and a first voltage sampling signal; a second detection circuit samples the input alternating current to output a second voltage sampling signal; a third detection circuit samples the first alternating current to output a second current sampling signal; a control circuit outputs an adjustment voltage according to the first current sampling signal, the first voltage sampling signal and the second voltage sampling signal; and a drive circuit outputs a first drive signal according to the adjustment voltage, the first current sampling signal and the second current sampling signal. Therefore, the maximum output power matching the input alternating current can be adaptively adjusted.

Description

Technical Field

[0001] The present application belongs to the technical field of power supply, and in particular relates to a power supply circuit and a welding machine. Background Art

[0002] The working principle of the welding machine power supply is as follows: the AC power is rectified by the first rectifier circuit, the power factor is corrected, and the capacitor is filtered to store energy to become high-voltage DC power. The high-voltage DC power is converted into a medium-frequency AC square wave through the inverter circuit. After the AC square wave is stepped down by the main transformer, it is rectified and filtered again to convert it into a low-voltage, high-current DC output. At the same time, the current negative feedback is used to regulate and control the output current to ensure that it is stable and consistent with the set current.

[0003] In complex power grid systems, grid voltages can vary from region to region or country to country. When grid voltage exceeds the normal operating voltage range of a welder, overvoltage damage to power components can occur. Undervoltage can lead to insufficient input power, affecting welding performance. Excessive input current can also cause overheating or damage to power components. Therefore, within a wide input voltage range, the welder must be able to adaptively adjust its maximum output power to match the input AC power, ensuring that all power components operate within their rated parameters. This includes power limiting and overload protection, which are crucial for stable and reliable operation. Summary of the Invention

[0004] The purpose of this application is to provide a power supply circuit and a welding machine, aiming to solve the problem that the relevant power supply circuit cannot adaptively adjust the maximum output power to match the input alternating current within a wide input voltage range.

[0005] An embodiment of the present application provides a power supply circuit, including:

[0006] a first conversion circuit configured to receive an input alternating current (AC) and convert the input AC to output a first DC;

[0007] an inverter circuit, electrically connected to the first conversion circuit, and configured to invert the first direct current according to a first drive signal to output a first alternating current;

[0008] a second conversion circuit, electrically connected to the inverter circuit, configured to convert the first alternating current to output a second direct current;

[0009] a first detection circuit, electrically connected to the second conversion circuit, configured to perform current detection on the second direct current to output a first current sampling signal, and perform voltage detection on the second direct current to output a first voltage sampling signal;

[0010] a second detection circuit, electrically connected to the first conversion circuit, configured to perform voltage sampling on the input AC power to output a second voltage sampling signal;

[0011] a third detection circuit, electrically connected to the second conversion circuit and the inverter circuit, configured to perform current sampling on the first alternating current to output a second current sampling signal;

[0012] a control circuit electrically connected to the first detection circuit and the second detection circuit, and configured to output a regulating voltage according to the first current sampling signal, the first voltage sampling signal, and the second voltage sampling signal;

[0013] The drive circuit is electrically connected to the inverter circuit, the control circuit, the first detection circuit and the third detection circuit, and is configured to output the first drive signal according to the adjustment voltage, the first current sampling signal and the second current sampling signal.

[0014] In one embodiment, the control circuit is specifically configured to obtain an output power threshold based on the second voltage sampling signal, and obtain output power based on the first current sampling signal and the first voltage sampling signal, and when the output power is greater than the output power threshold, reduce the regulation voltage and output it.

[0015] In one embodiment, the first driving signal is a pulse width modulation (PWM) signal; and the driving circuit includes:

[0016] an adding circuit, electrically connected to the control circuit and the first detection circuit, and configured to add the voltage of the first current sampling signal and the adjustment voltage to obtain a composite voltage;

[0017] A PWM signal generating circuit is electrically connected to the inverter circuit, the adding circuit, and the third detection circuit, and is configured to take a preset ratio of the second current sampling signal to obtain a first voltage. When the first voltage is greater than the composite voltage, the PWM signal of the current cycle is stopped from being output, and the PWM signal is output in the next cycle.

[0018] In one embodiment, the PWM signal generating circuit is further configured to stop outputting the PWM signal in a current cycle and output the PWM signal in a next cycle when the first voltage is greater than a first preset voltage.

[0019] In one embodiment, the driving signal is a PWM signal; and the power supply circuit further includes:

[0020] a comparison circuit, electrically connected to the third detection circuit and the control circuit, and configured to output an overcurrent signal when the voltage of the second current sampling signal is greater than a second preset voltage;

[0021] The control circuit is further configured to output a shutdown signal according to the overcurrent signal;

[0022] The PWM signal generating circuit is also electrically connected to the control circuit, and is further configured to stop outputting the PWM signal of the current cycle and output the PWM signal in the next cycle when receiving the shutdown signal.

[0023] In one embodiment, the first conversion circuit includes:

[0024] a first rectifier circuit configured to receive the input AC power and convert the input AC power to output a third DC power;

[0025] A power factor correction (PFC) circuit is electrically connected to the first rectifier circuit and the inverter circuit, and is configured to perform power factor correction on the second direct current to output the first direct current.

[0026] In one embodiment, it further includes:

[0027] a fourth detection circuit, electrically connected to the first rectifier circuit and the PFC circuit, and configured to perform current detection on the third direct current to output a third current sampling signal;

[0028] The control circuit is also electrically connected to the PFC circuit, and is further configured to stop outputting the second drive signal when the voltage of the third current sampling signal is greater than a third preset voltage;

[0029] The PFC circuit is further configured to disconnect the output of the first DC power according to the cessation of the second driving signal.

[0030] In one embodiment, it further includes:

[0031] a fifth detection circuit, electrically connected to the first rectifier circuit and the PFC circuit, and configured to perform voltage detection on the third DC power to output a third voltage sampling signal;

[0032] The control circuit is also electrically connected to the PFC circuit, and is further configured to stop outputting the second drive signal when the voltage of the third voltage sampling signal is less than a fourth preset voltage;

[0033] The PFC circuit is further configured to disconnect the output of the first DC power according to the cessation of the second driving signal.

[0034] In one embodiment, the control circuit is further configured to stop outputting the first driving signal when the voltage of the second voltage sampling signal is greater than a fifth preset voltage;

[0035] The inverter circuit is further configured to cut off output of the first AC power in response to the cessation of the first drive signal.

[0036] In one embodiment, the control circuit is further configured to output a control signal when the voltage of the second voltage sampling signal is greater than a sixth preset voltage;

[0037] The power supply circuit further includes:

[0038] The switch circuit is electrically connected to the second detection circuit and the first conversion circuit, and is configured to be connected to the input AC power and disconnected according to the control signal to stop the output of the input AC power.

[0039] In one embodiment, the second conversion circuit includes:

[0040] a voltage conversion circuit, electrically connected to the inverter circuit, and configured to convert the first alternating current to output a second alternating current;

[0041] The second rectifier circuit is electrically connected to the voltage transformation circuit and the first detection circuit, and is configured to rectify the second alternating current to output the second direct current.

[0042] An embodiment of the present invention further provides a welding machine, which includes the above-mentioned power supply circuit.

[0043] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: since the first detection circuit performs current detection and voltage detection on the second direct current to output a first current sampling signal and a first voltage sampling signal; the second detection circuit performs voltage sampling on the input alternating current to output a second voltage sampling signal; the control circuit outputs an adjustment voltage based on the first current sampling signal, the first voltage sampling signal and the second voltage sampling signal; the drive circuit outputs the first drive signal based on the adjustment voltage, the first current sampling signal and the second current sampling signal to drive the inverter circuit; since the adjustment signal is generated based on the voltage sampling signal of the input alternating current, and the first drive signal of the inverter circuit is generated based on the adjustment signal, the maximum output power matching the input alternating current can be adaptively adjusted within a wide input voltage range, thereby being applicable to power grids with a wide voltage range. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical inventions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 A schematic diagram of a power supply circuit according to an embodiment of the present application;

[0046] Figure 2 A schematic structural diagram of a driving circuit in a power supply circuit provided in an embodiment of the present application;

[0047] Figure 3 Another structural schematic diagram of a power supply circuit provided in one embodiment of the present application;

[0048] Figure 4 A schematic structural diagram of a first conversion circuit in a power supply circuit provided in an embodiment of the present application;

[0049] Figure 5 Another structural schematic diagram of a power supply circuit provided in one embodiment of the present application;

[0050] Figure 6 Another structural schematic diagram of a power supply circuit provided in one embodiment of the present application;

[0051] Figure 7 Another structural schematic diagram of a power supply circuit provided in one embodiment of the present application;

[0052] Figure 8 A schematic structural diagram of a second conversion circuit in a power supply circuit provided in an embodiment of the present application;

[0053] Figure 9 A partial exemplary circuit schematic diagram of a power supply circuit provided in one embodiment of the present application. DETAILED DESCRIPTION

[0054] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0055] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0056] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0058] Figure 1 The following is a schematic diagram of the structure of the power supply circuit provided in a preferred embodiment of the present application. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0059] The power supply circuit includes a first conversion circuit 11 , an inverter circuit 12 , a second conversion circuit 13 , a first detection circuit 14 , a second detection circuit 15 , a third detection circuit 16 , a control circuit 17 and a drive circuit 18 .

[0060] The first conversion circuit 11 is configured to receive an input AC power and convert the input AC power to output a first DC power;

[0061] The inverter circuit 12 is electrically connected to the first conversion circuit 11 and configured to invert the first direct current according to the first driving signal to output a first alternating current;

[0062] The second conversion circuit 13 is electrically connected to the inverter circuit 12 and configured to convert the first alternating current to output a second direct current;

[0063] a first detection circuit 14, electrically connected to the second conversion circuit 13, configured to perform current detection on the second DC power to output a first current sampling signal, and perform voltage detection on the second DC power to output a first voltage sampling signal;

[0064] The second detection circuit 15 is electrically connected to the first conversion circuit 11 and configured to perform voltage sampling on the input AC power to output a second voltage sampling signal;

[0065] a third detection circuit 16 , electrically connected to the second conversion circuit 13 and the inverter circuit 12 , and configured to perform current sampling on the first alternating current to output a second current sampling signal;

[0066] The control circuit 17 is electrically connected to the first detection circuit 14 and the second detection circuit 15 and is configured to output a regulating voltage according to the first current sampling signal, the first voltage sampling signal and the second voltage sampling signal;

[0067] The driving circuit 18 is electrically connected to the inverter circuit 12 , the control circuit 17 , the first detection circuit 14 and the third detection circuit 16 , and is configured to output a driving signal according to the adjustment voltage, the first current sampling signal and the second current sampling signal.

[0068] In a specific implementation, the control circuit 17 is further configured to stop outputting the first drive signal when the voltage of the second voltage sampling signal is greater than the fifth preset voltage; the inverter circuit 12 is further configured to disconnect the output of the first alternating current according to the stopping of the first drive signal.

[0069] By performing voltage detection and overvoltage protection on the input AC power, the inverter circuit 12 is shut down in time to prevent damage to the power devices in the inverter circuit 12. At this time, the control circuit 17 can also output a display signal to the display panel for overvoltage alarm indication.

[0070] It is worth emphasizing that the control circuit 17 is specifically configured to obtain the output power threshold according to the second voltage sampling signal, and obtain the output power according to the first current sampling signal and the first voltage sampling signal. When the output power is greater than the output power threshold, the regulated voltage is reduced and output. In this case, the first driving signal can be a PWM signal; Figure 2 As shown, the driving circuit 18 includes an adding circuit and a PWM signal generating circuit.

[0071] The adding circuit is electrically connected to the control circuit 17 and the first detection circuit 14, and is configured to add the voltage of the first current sampling signal and the adjustment voltage to obtain a composite voltage; in a specific implementation, the adjustment voltage is a negative voltage and the voltage of the first current sampling signal is a positive voltage.

[0072] The PWM signal generating circuit is electrically connected to the inverter circuit 12, the adding circuit and the third detection circuit 16, and is configured to take a preset ratio of the second current sampling signal to obtain a first voltage. When the first voltage is greater than the composite voltage, the PWM signal of the current cycle is stopped and the PWM signal is output in the next cycle.

[0073] It should be noted that the output power threshold value obtained by the control circuit 17 according to the second voltage sampling signal is specifically:

[0074] Calculate the output power threshold according to the following formula: P 2max =P 1max η=I 1max ·U1·η

[0075] Among them, U1 is the voltage of the input AC power, I 1max is the maximum allowable input current, P 2max is the output power threshold, η is the conversion efficiency, P 1max is the maximum input power.

[0076] The control circuit 17 obtains the output power according to the first current sampling signal and the first voltage sampling signal as follows:

[0077] Calculate the output power according to the following formula: P2=I2·U2

[0078] Wherein, P2 is the output power, U2 is the voltage of the second direct current, and I2 is the current of the second direct current.

[0079] When the output power is greater than the output power threshold, the control circuit 17 reduces and outputs the regulated voltage. The adding circuit adds the voltage of the first current sampling signal and the regulated voltage to obtain a composite voltage. The PWM signal generating circuit takes a preset ratio of the second current sampling signal to obtain the first voltage. When the first voltage is greater than the composite voltage, the PWM signal of the current cycle is stopped from being output, and the PWM signal is output in the next cycle. That is, when P2>P 2max When the regulation voltage decreases, the duty cycle of the PWM signal decreases, causing the output current to drop, making P2 equal to P 2max The second DC current is adjusted according to the input DC voltage, thereby achieving the purpose of limiting the output power. The pulse-by-pulse current limiting method implemented by the software running on the control circuit 17 can ensure that the power is not overloaded and normal operation can be maintained even when the input voltage is low for a long time or the output power is too high.

[0080] In a specific implementation, the PWM signal generating circuit is further configured to stop outputting the PWM signal of the current cycle and output the PWM signal in the next cycle when the first voltage is greater than the first preset voltage.

[0081] By setting an upper limit value (first preset voltage) for the first voltage, output overcurrent is prevented and power devices in the power supply circuit are protected.

[0082] The driving signal is a PWM signal; Figure 3 As shown, the power supply circuit further includes a comparison circuit 19 .

[0083] The comparison circuit 19 is electrically connected to the third detection circuit 16 and the control circuit 17, and is configured to output an overcurrent signal when the voltage of the second current sampling signal is greater than the second preset voltage;

[0084] The control circuit 17 is further configured to output a shutdown signal according to the overcurrent signal;

[0085] The PWM signal generating circuit is also electrically connected to the control circuit 17 and is further configured to stop outputting the PWM signal of the current cycle and output the PWM signal in the next cycle when receiving a shutdown signal.

[0086] By generating an overcurrent signal based on the second current sampling signal and then a shutdown signal based on the overcurrent signal, the PWM signal generation circuit stops outputting the PWM signal in the current cycle and outputs the PWM signal in the next cycle, further preventing output overcurrent and protecting the power devices in the power supply circuit. This pulse-by-pulse current limiting method through hardware circuitry has a fast response speed and can quickly limit sudden current overshoot signals.

[0087] like Figure 4 As shown, the first conversion circuit 11 includes a first rectifier circuit 111 and a PFC circuit 112 .

[0088] The first rectifier circuit 111 is configured to receive an input AC power and convert the input AC power to output a third DC power;

[0089] The PFC circuit 112 is electrically connected to the first rectifier circuit 111 and the inverter circuit 12 , and is configured to perform power factor correction on the second DC power to output the first DC power.

[0090] AC-DC conversion and power factor correction are achieved through the first rectifier circuit 111 and the PFC circuit 112, thereby improving the efficiency of electric energy.

[0091] like Figure 5 As shown, the power supply circuit further includes a fourth detection circuit 20 .

[0092] a fourth detection circuit 20 , electrically connected to the first rectifier circuit 111 and the PFC circuit 112 , and configured to perform current detection on the third direct current to output a third current sampling signal;

[0093] The control circuit 17 is also electrically connected to the PFC circuit 112 and is further configured to stop outputting the second drive signal when the voltage of the third current sampling signal is greater than a third preset voltage;

[0094] The PFC circuit 112 is further configured to cut off the output of the first DC power according to the cessation of the second driving signal.

[0095] The fourth detection circuit 20 and the control circuit 17 implement overcurrent protection for the PFC circuit 112. When the current of the third DC power source exceeds the upper limit of the allowable current, the PFC circuit 112 is turned off to prevent inductor saturation and overcurrent damage to power devices such as IGBTs.

[0096] like Figure 6 As shown, the power supply circuit further includes a fifth detection circuit 21 .

[0097] a fifth detection circuit 21 , electrically connected to the first rectifier circuit 111 and the PFC circuit 112 , and configured to perform voltage detection on the third DC power to output a third voltage sampling signal;

[0098] The control circuit 17 is also electrically connected to the PFC circuit 112 and is further configured to stop outputting the second drive signal when the voltage of the third voltage sampling signal is less than a fourth preset voltage;

[0099] The PFC circuit 112 is further configured to cut off the output of the first DC power according to the cessation of the second driving signal.

[0100] The fourth detection circuit 20 and the control circuit 17 are used to implement undervoltage protection of the PFC circuit 112 , thereby preventing damage to power devices caused by insufficient input power.

[0101] In a specific implementation, the control circuit 17 is further configured to output a control signal when the voltage of the second voltage sampling signal is greater than the sixth preset voltage; Figure 7 As shown, the power supply circuit further includes a switch circuit 22 .

[0102] The switch circuit 22 is electrically connected to the second detection circuit 15 and the first conversion circuit 11 , and is configured to receive the input AC power and be disconnected according to a control signal to stop outputting the input AC power.

[0103] When the input AC voltage exceeds the sixth preset voltage, the trigger switch circuit 22 (such as the main power relay) is disconnected to prevent damage to power devices such as electrolytic capacitors and IGBTs due to overvoltage. At the same time, the control circuit 17 can output a display signal to the display panel to indicate an overvoltage alarm.

[0104] like Figure 8 As shown, the second conversion circuit 13 includes a voltage transformation circuit 131 and a second rectifier circuit 132 .

[0105] The voltage conversion circuit 131 is electrically connected to the inverter circuit 12 and configured to convert the first alternating current to output a second alternating current;

[0106] The second rectifier circuit 132 is electrically connected to the transformer circuit 131 and the first detection circuit 14 , and is configured to rectify the second alternating current to output a second direct current.

[0107] The voltage conversion circuit 131 and the second rectifier circuit 132 realize AC conversion and AC-DC conversion, thereby obtaining stable high-current DC power.

[0108] Figure 9A partial exemplary circuit structure of a power supply circuit provided by an embodiment of the present invention is shown. For ease of illustration, only the portion related to the embodiment of the present invention is shown, which is described in detail as follows:

[0109] The control circuit 17 includes a microprocessor U1.

[0110] The first general input and output terminal P1.0 of the microprocessor U1 serves as the first current sampling signal input terminal of the control circuit 17 and is connected to the first detection circuit 14 to receive the first current sampling signal; the second general input and output terminal P1.1 of the microprocessor U1 serves as the first voltage sampling signal input terminal of the control circuit 17 and is connected to the first detection circuit 14 to receive the first voltage sampling signal; the third general input and output terminal P1.2 of the microprocessor U1 serves as the second voltage sampling signal input terminal of the control circuit 17 and is connected to the second detection circuit 15 to receive the second voltage sampling signal; the fourth general input and output terminal P1.3 of the microprocessor U1 serves as the shutdown signal output terminal of the control circuit 17 and is connected to the PWM signal generating circuit to output the shutdown signal; the fifth general input and output terminal P1.4 of the microprocessor U1 serves as the overcurrent signal input terminal of the control circuit 17 and is connected to the comparison circuit 19 to receive the overcurrent signal; the sixth general input and output terminal P1.5 of the microprocessor U1 serves as the adjustment signal output terminal of the control circuit 17 and is connected to the drive circuit 18 (adding circuit) to output the adjustment voltage.

[0111] The control circuit 17 is simple and reliable.

[0112] The adding circuit includes an operational amplifier U2 , a first capacitor C1 , a second capacitor C2 , a first resistor R1 , a second resistor R2 , and a third resistor R3 .

[0113] An inverting input terminal of the operational amplifier U2 is connected to a first end of the first resistor R1, a first end of the second resistor R2, a first end of the third resistor R3, and a first end of the first capacitor C1; a second end of the first resistor R1 serves as an adjustment voltage input terminal of the adding circuit and is connected to the control circuit 17 to receive an adjustment signal; a second end of the second resistor R2 serves as a first current sampling signal input terminal of the adding circuit and is connected to the first detection circuit 14 to receive the first current sampling signal; a second end of the third resistor R3 is connected to a first end of the second capacitor C2; an output terminal of the operational amplifier U2, a second end of the first capacitor C1, and a second end of the second capacitor C2 collectively serve as a composite voltage output terminal of the adding circuit and are connected to the PWM signal generating circuit to output a composite voltage; a non-inverting input terminal of the operational amplifier U2 is connected to a power ground.

[0114] The PWM signal generating circuit includes a PWM controller U3 , a third capacitor C3 , a fourth resistor R4 , a fifth resistor R5 , a sixth resistor R6 , a seventh resistor R7 , and an eighth resistor R8 .

[0115] The current limiting terminal C / S of the PWM controller U3 is connected to the first end of the fifth resistor R5, the first end of the third capacitor C3, and the first end of the sixth resistor R6, and the reference voltage output terminal VREF of the PWM controller U3 is connected to the second end of the fifth resistor R5; the current sensing comparator positive input terminal C / S+ of the PWM controller U3, the first end of the fourth resistor R4, and the first end of the eighth resistor R8 collectively serve as the second current sampling signal input terminal of the PWM signal generating circuit, and are connected to the third detection circuit 16 to receive the second current sampling signal; the first PWM drive signal output terminal OUTA of the PWM controller U3 and the second PWM drive signal output terminal OUTB of the PWM controller U3 collectively serve as the PWM signal output terminal of the PWM signal generating circuit, and are connected to the inverter circuit 12 to output the first drive signal; the error amplifier positive phase of the PWM controller U3 The input terminal E / A+ is connected to the first end of the ninth resistor R9; the second end of the ninth resistor R9 serves as the composite signal input terminal of the PWM signal generating circuit and is connected to the adding circuit to receive the composite signal; the error amplifier inverting input terminal E / A- of the PWM controller U3 is connected to the error amplifier output terminal COMP of the PWM controller U3, the bias voltage input terminal VIN of the PWM controller U3 is connected to the first power supply, the external shutdown signal input terminal SHUTDOWN of the PWM controller U3, the first end of the seventh resistor R7 and the second end of the eighth resistor R8 collectively serve as the shutdown signal input terminal of the PWM signal generating circuit and are connected to the control circuit 17 to receive the shutdown signal; the current sensing comparator inverting input terminal C / S- of the PWM controller U3, the second end of the sixth resistor R6, the second end of the third capacitor C3 and the second end of the seventh resistor R7 are commonly connected to the power ground.

[0116] The following three functions are implemented by the PWM controller U3: 1) The second current sampling signal is proportionally scaled to obtain a first voltage (the voltage at the non-inverting input terminal C / S+ of the current sensing comparator of the PWM controller U3). When the first voltage is greater than the composite voltage, the PWM signal output for the current cycle is stopped, and the PWM signal is output in the next cycle. 2) When the external shutdown signal input terminal SHUTDOWN of the PWM controller U3 is connected to the shutdown voltage, the PWM signal output for the current cycle is stopped, and the PWM signal is output in the next cycle. 3) When the first voltage is greater than the voltage at the current limiting terminal C / S of the PWM controller U3 (the first preset voltage), the PWM signal output for the current cycle is stopped, and the PWM signal is output in the next cycle.

[0117] The comparison circuit 19 includes a comparator U4 , a tenth resistor R10 , an eleventh resistor R11 , and a twelfth resistor R12 .

[0118] The non-inverting input terminal of the comparator U4 is connected to the first end of the eleventh resistor R11, and the inverting input terminal of the comparator U4 is connected to the first end of the tenth resistor R10 and the first end of the twelfth resistor R12; the output terminal of the comparator U4 serves as the overcurrent signal output terminal of the comparison circuit 19 and is connected to the control circuit 17 to output the overcurrent signal; the second end of the eleventh resistor R11 serves as the second current sampling signal input terminal of the comparison circuit 19 and is connected to the third detection circuit 16 to receive the second current sampling signal; the second end of the tenth resistor R10 is connected to the second power supply VBB, and the second end of the twelfth resistor R12 is connected to the power ground.

[0119] The comparison circuit 19 is simple and reliable.

[0120] The following is combined with the working principle Figure 9 As shown for further explanation:

[0121] The first conversion circuit 11 converts the input AC power to output a first DC power; the inverter circuit 12 inverts the first DC power according to the first drive signal to output a first AC power; the second conversion circuit 13 converts the first AC power to output a second DC power; the first detection circuit 14 detects the current of the second DC power and outputs a first current sampling signal to the first universal input / output terminal P1.0 of the microprocessor U1 and the inverting input terminal of the operational amplifier U2, and detects the voltage of the second DC power and outputs a first voltage sampling signal to the second universal input / output terminal P1.1 of the microprocessor U1; the second detection circuit 15 samples the voltage of the input AC power and outputs a second voltage sampling signal to the third universal input / output terminal P1.2 of the microprocessor U1; and the third detection circuit 16 samples the current of the first AC power and outputs a second current sampling signal to the non-inverting input terminal of the comparator U4. The first drive signal may be a PWM signal.

[0122] The microprocessor U1 obtains the output power threshold according to the second voltage sampling signal, obtains the output power according to the first current sampling signal and the first voltage sampling signal, and reduces and outputs the regulated voltage when the output power is greater than the output power threshold.

[0123] The operational amplifier U2 adds the voltage of the first current sampling signal and the regulation voltage to obtain a composite voltage, and outputs the composite voltage from the output terminal of the operational amplifier U2 to the non-inverting input terminal E / A+ of the error amplifier of the PWM controller U3.

[0124] The tenth resistor R10 and the twelfth resistor R12 divide the voltage of the second power supply to output a second preset voltage. When the voltage of the second current sampling signal is greater than the second preset voltage, the comparator U4 outputs an overcurrent signal to the fifth general input and output terminal P1.4 of the microprocessor U1. The microprocessor U1 outputs a shutdown signal to the external shutdown signal input terminal SHUTDOWN of the PWM controller U3 according to the overcurrent signal.

[0125] The fourth resistor R4, the eighth resistor R8, and the seventh resistor R7 take a preset proportion of the second current sampling signal to obtain a first voltage (the voltage of the non-inverting input terminal C / S+ of the current sensing comparator of the PWM controller U3). When the first voltage is greater than the composite voltage, the PWM controller U3 stops outputting the PWM signal of the current cycle from the first PWM drive signal output terminal OUTA of the PWM controller U3 and the second PWM drive signal output terminal OUTB of the PWM controller U3, and outputs the PWM signal from the first PWM drive signal output terminal OUTA of the PWM controller U3 and the second PWM drive signal output terminal OUTB of the PWM controller U3 in the next cycle.

[0126] When the external shutdown signal input terminal SHUTDOWN of the PWM controller U3 is connected to the shutdown voltage, the PWM signal of the current cycle is stopped from being output from the first PWM drive signal output terminal OUTA of the PWM controller U3 and the second PWM drive signal output terminal OUTB of the PWM controller U3, and the PWM signal is output from the first PWM drive signal output terminal OUTA of the PWM controller U3 and the second PWM drive signal output terminal OUTB of the PWM controller U3 in the next cycle.

[0127] When the first voltage is greater than the voltage of the current limiting terminal C / S of the PWM controller U3 (the first preset voltage), the output of the PWM signal of the current cycle from the first PWM drive signal output terminal OUTA of the PWM controller U3 and the second PWM drive signal output terminal OUTB of the PWM controller U3 is stopped, and the PWM signal is output from the first PWM drive signal output terminal OUTA of the PWM controller U3 and the second PWM drive signal output terminal OUTB of the PWM controller U3 in the next cycle.

[0128] An embodiment of the present invention further provides a welding machine, which includes the above-mentioned power supply circuit.

[0129] In an embodiment of the present invention, a first conversion circuit receives input AC power and converts the input AC power to output a first DC power. An inverter circuit inverts the first DC power according to a first drive signal to output a first AC power. A second conversion circuit converts the first AC power to output a second DC power. A first detection circuit detects the current of the second DC power to output a first current sampling signal, and detects the voltage of the second DC power to output a first voltage sampling signal. A second detection circuit samples the voltage of the input AC power to output a second voltage sampling signal. A third detection circuit samples the current of the first AC power to output a second current sampling signal. A control circuit outputs an adjusted voltage based on the first current sampling signal, a first voltage sampling signal, and a second voltage sampling signal. A drive circuit outputs a first drive signal based on the adjusted voltage, the first current sampling signal, and the second current sampling signal. Because the adjusted signal is generated based on the voltage sampling signal of the input AC power, and the first drive signal of the inverter circuit is generated based on the adjusted signal, the maximum output power matching the input AC power can be adaptively adjusted within a wide input voltage range, thereby being applicable to power grids with a wide voltage range.

[0130] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0131] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A power supply circuit, characterized in that: include: a first conversion circuit configured to receive an input alternating current (AC) and convert the input AC to output a first DC; an inverter circuit, electrically connected to the first conversion circuit, and configured to invert the first direct current according to a first drive signal to output a first alternating current; a second conversion circuit, electrically connected to the inverter circuit, configured to convert the first alternating current to output a second direct current; a first detection circuit, electrically connected to the second conversion circuit, configured to perform current detection on the second direct current to output a first current sampling signal, and perform voltage detection on the second direct current to output a first voltage sampling signal; a second detection circuit, electrically connected to the first conversion circuit, configured to perform voltage sampling on the input AC power to output a second voltage sampling signal; a third detection circuit, electrically connected to the first conversion circuit and the inverter circuit, and configured to perform current sampling on the first alternating current to output a second current sampling signal; a control circuit electrically connected to the first detection circuit and the second detection circuit, and configured to output a regulating voltage according to the first current sampling signal, the first voltage sampling signal, and the second voltage sampling signal; a drive circuit electrically connected to the inverter circuit, the control circuit, the first detection circuit, and the third detection circuit, and configured to output the first drive signal based on the regulated voltage, the first current sampling signal, and the second current sampling signal; the control circuit is specifically configured to obtain an output power threshold based on the second voltage sampling signal, obtain output power based on the first current sampling signal and the first voltage sampling signal, and reduce and output the regulated voltage when the output power is greater than the output power threshold; The first driving signal is a PWM signal; the driving circuit includes: an adding circuit, electrically connected to the control circuit and the first detection circuit, and configured to add the voltage of the first current sampling signal and the adjustment voltage to obtain a composite voltage; A PWM signal generating circuit is electrically connected to the inverter circuit, the adding circuit, and the third detection circuit, and is configured to take a preset ratio of the second current sampling signal to obtain a first voltage. When the first voltage is greater than the composite voltage, the PWM signal of the current cycle is stopped from being output, and the PWM signal is output in the next cycle.

2. The power supply circuit according to claim 1, wherein: The PWM signal generating circuit is further configured to stop outputting the PWM signal in a current cycle and output the PWM signal in a next cycle when the first voltage is greater than a first preset voltage.

3. The power supply circuit according to claim 1, wherein: The driving signal is a PWM signal; the power supply circuit further includes: a comparison circuit, electrically connected to the third detection circuit and the control circuit, and configured to output an overcurrent signal when the voltage of the second current sampling signal is greater than a second preset voltage; The control circuit is further configured to output a shutdown signal according to the overcurrent signal; The PWM signal generating circuit is also electrically connected to the control circuit, and is further configured to stop outputting the PWM signal of the current cycle and output the PWM signal in the next cycle when receiving the shutdown signal.

4. The power supply circuit according to claim 1, wherein: The first conversion circuit includes: a first rectifier circuit configured to receive the input AC power and convert the input AC power to output a third DC power; The PFC circuit is electrically connected to the first rectifier circuit and the inverter circuit, and is configured to perform power factor correction on the third DC power to output the first DC power.

5. The power supply circuit according to claim 4, wherein: Also includes: a fourth detection circuit, electrically connected to the first rectifier circuit and the PFC circuit, and configured to perform current detection on the third direct current to output a third current sampling signal; The control circuit is also electrically connected to the PFC circuit, and is further configured to stop outputting the second drive signal when the voltage of the third current sampling signal is greater than a third preset voltage; The PFC circuit is further configured to disconnect the output of the first DC power according to the cessation of the second driving signal.

6. The power supply circuit according to claim 4, wherein: Also includes: a fifth detection circuit, electrically connected to the first rectifier circuit and the PFC circuit, and configured to perform voltage detection on the third DC power to output a third voltage sampling signal; The control circuit is also electrically connected to the PFC circuit, and is further configured to stop outputting the second drive signal when the voltage of the third voltage sampling signal is less than a fourth preset voltage; The PFC circuit is further configured to disconnect the output of the first DC power according to the cessation of the second driving signal.

7. The power supply circuit according to claim 1, wherein: The control circuit is further configured to stop outputting the first driving signal when the voltage of the second voltage sampling signal is greater than a fifth preset voltage; The inverter circuit is further configured to cut off output of the first AC power in response to the cessation of the first drive signal.

8. The power supply circuit according to claim 1, wherein: The control circuit is further configured to output a control signal when the voltage of the second voltage sampling signal is greater than a sixth preset voltage; The power supply circuit further includes: The switch circuit is electrically connected to the second detection circuit and the first conversion circuit, and is configured to be connected to the input AC power and disconnected according to the control signal to stop the output of the input AC power.

9. The power supply circuit according to claim 1, wherein: The second conversion circuit includes: a voltage conversion circuit, electrically connected to the inverter circuit, and configured to convert the first alternating current to output a second alternating current; The second rectifier circuit is electrically connected to the voltage transformation circuit and the first detection circuit, and is configured to rectify the second alternating current to output the second direct current.

10. A welding machine, characterized in that: The welding machine comprises the power supply circuit according to any one of claims 1 to 7.

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