Open-circuit voltage adjustment method for power supply, power supply circuit, power supply device and welding machine

Abstract

This application belongs to the field of power supply technology and provides a method for adjusting the open-circuit voltage of a power supply, a power supply circuit, a power supply device, and a welding machine. By driving the first power transistor switching module and the second power transistor switching module to conduct alternately, the transformer module operates in a state of extremely low energy density, thereby achieving the purpose of adjusting the open-circuit voltage of the power supply over a wide range. By using frequency hopping technology to reduce the equivalent driving frequency of the upper and lower switching transistors in the dual-transistor forward topology circuit in the power supply, the energy transfer density of the transformer is further reduced. The voltage regulation module controls the equivalent resistance at the output terminal of the power supply, and the auxiliary step-down module provides auxiliary voltage, thereby achieving the purpose of compound adjustment of the open-circuit voltage of the power supply. Finally, the rectification and freewheeling modules rectify and freewheel the voltage signal output by the transformer module. This solves the problem that the open-circuit voltage of existing welding power supplies is mostly not adjustable, or very rarely adjustable but with a small adjustment range, resulting in poor adaptability to welding processes.

Description

Technical Field

[0001] This application belongs to the field of power supply technology, and particularly relates to a method for adjusting the open-circuit voltage of a power supply, a power supply circuit, a power supply device, and a welding machine. Background Technology

[0002] The output voltage of a welding power supply consists of open-circuit voltage and operating voltage. Open-circuit voltage refers to the output voltage measured when the power supply is powered on and no load is connected to the output terminal, i.e., the voltage when not in operation, typically between 50V and 90V. Operating voltage refers to the voltage during normal welding after the arc is ignited, usually around 15V to 40V. To meet the requirements for arc ignition during welding, the open-circuit voltage of the welding power supply is generally designed to be much higher than the operating voltage. However, a higher open-circuit voltage cannot meet the output voltage requirements of various safety regulations and different welding processes. Therefore, it is necessary to design a method to adjust the open-circuit voltage of the welding power supply.

[0003] To adjust the open-circuit voltage of the welding power supply, the following solutions are available:

[0004] 1. To design a welding power supply with a correspondingly low open-circuit voltage for a specific welding process or a limited number of welding processes, in order to meet the specific welding process and some safety regulations, the general approach is to increase the turns ratio of the main transformer of the welding power supply, and then connect a suitable, fixed load in parallel at the output terminal of the transformer's secondary side, such as... Figure 1 As shown, VA is the welding power source, and RA1 is the load resistor connected in parallel at the output terminal. However, this scheme can only meet some safety requirements. For example, the national standard "Safety Requirements for Arc Welding Equipment" stipulates that the rated open-circuit voltage should not exceed the peak value of DC 103V. It cannot comply with more stringent safety regulations, and there is no voltage reduction device (VRD) measure, which poses certain personal safety hazards. Secondly, the level of open-circuit voltage greatly affects the performance of arc initiation and arc stabilization. The higher the open-circuit voltage, the easier it is to initiate and stabilize the arc. Especially for some special welding processes, there are certain requirements for the open-circuit voltage. However, the open-circuit voltage of the welding power source designed in this scheme cannot be changed once designed. Welding power sources with corresponding open-circuit voltages can only be designed for different welding processes. This lack of flexibility also limits the types of welding processes that a single welding power source can achieve. It is only suitable for single-function, low-cost welding power source applications.

[0005] 2. For example Figure 2As shown, VB1 is the main welding power supply, with an open-circuit voltage typically ranging from 50V to 90V. VB2 is an independent safety voltage source, with a generally accepted safe voltage not exceeding 36V and a continuous contact safe voltage not exceeding 24V. The positive terminal of VB2 is connected to the positive output terminal of VB1 via electronic switch SB1, current-limiting resistor RB1, and forward diode DB1. The negative terminals of VB2 and VB1 are connected as a common reference. When the welding circuit enters an open-circuit state, the welding power supply output current is zero. Upon recognizing the zero current, the system immediately shuts off the output of the main power supply VB1 and simultaneously closes SB1, allowing the voltage of VB2 to flow through RB1... DB1 is applied to the welding power supply output, creating a low open-circuit voltage used to determine whether welding should begin. When welding starts, the output changes from open to short-circuit, pulling the open-circuit voltage down. The welding machine control system recognizes the low voltage and immediately disconnects SB1, simultaneously activating the main welding power supply VB1 to provide the required open-circuit or operating voltage. After the welding arc is interrupted or completed, the welding circuit returns to an open-circuit state, and the process repeats, outputting a lower open-circuit voltage to determine whether welding should begin. This achieves the adjustment of the welding power supply's open-circuit voltage. This solution effectively addresses common safety regulations, but it requires an additional independent safety voltage source VB2, an electronic switch SB1 (MOSFET, BJT, relay contact, etc.), a current-limiting resistor RB1, and a high-voltage diode DB1. This increases hardware costs and circuit complexity, significantly burdening debugging. Furthermore, this solution cannot adjust the open-circuit voltage during welding operation, thus failing to apply the optimal open-circuit arc-starting voltage based on different welding process characteristics to achieve optimal arc-starting voltage configuration. Furthermore, due to the low open-circuit voltage, if the transition from the open-circuit state to the welding working state is not handled properly when starting welding, it will seriously affect the arc initiation performance and bring about a poor welding experience.

[0006] 3. A digital regulator is used to perform closed-loop control of the output voltage under open-circuit conditions, thereby achieving open-circuit voltage adjustment within a certain range. This software adjustment scheme requires a suitable constant-resistance load connected in parallel at the power output, similar to Scheme 1, to lower the open-circuit voltage. This scheme uses pure software control for constant-voltage closed-loop control under open-circuit conditions. This method can only adjust the average open-circuit voltage; the peak voltage cannot be guaranteed to meet safety requirements, and the linear adjustment range is limited, depending on the size of the constant-resistance load connected in parallel at the output. A larger load resistance results in a smaller adjustment range, and a smaller load resistance results in a larger adjustment range. However, smaller load resistances generate greater standby power consumption. Therefore, from an energy efficiency perspective, the load resistance cannot be too small, which leads to a limited linear adjustment range for the average open-circuit voltage, and this range is adjacent to the rated open-circuit voltage. In this case, the peak voltage will also exceed safety requirements. Because the linear adjustment range of the open-circuit voltage is small and relatively large (close to the rated open-circuit voltage), the optimal configuration of the arcing voltage cannot be achieved. Summary of the Invention

[0007] The purpose of this application is to provide a method for adjusting the open-circuit voltage of a power supply, a power supply circuit, a power supply device, and a welding machine, which can solve the problems of small open-circuit voltage adjustment range and poor adaptability to welding processes in existing welding power supplies.

[0008] The first aspect of this application provides a method for adjusting the open-circuit voltage of a power supply. The power supply includes a first power transistor switching module, a transformer module, a second power transistor switching module, and a rectification and freewheeling module. The current input terminal of the first power transistor switching module is connected to the positive terminal of a DC bus, the current output terminal of the first power transistor switching module is connected to the first end of the primary winding of the transformer module, the current input terminal of the second power transistor switching module is connected to the second end of the primary winding of the transformer module, and the current output terminal of the second power transistor switching module is connected to the negative terminal of the DC bus.

[0009] The open-circuit voltage adjustment method includes:

[0010] The first power transistor switching module and the second power transistor switching module are alternately turned on;

[0011] The voltage signal output by the transformer module is rectified and freewheeled by a rectification and freewheeling module; wherein the rectification and freewheeling module is connected to the secondary winding of the transformer module.

[0012] In one embodiment, the open-circuit voltage adjustment method further includes:

[0013] Frequency hopping technology is used to adjust the switching frequencies of the first power transistor switching module and the second power transistor switching module in order to adjust the energy transfer density of the transformer module.

[0014] In one embodiment, the open-circuit voltage adjustment method further includes:

[0015] A voltage regulation module is used to adjust the equivalent resistance at the output terminal of the power supply in order to regulate the open-circuit voltage of the power supply.

[0016] In one embodiment, the open-circuit voltage adjustment method further includes:

[0017] An auxiliary step-down module is used to output an auxiliary voltage based on the input auxiliary power supply control signal.

[0018] A second aspect of this application provides a power supply circuit, the power supply circuit comprising:

[0019] The first power transistor switching module has its current input terminal connected to the positive terminal of the DC bus.

[0020] A transformer module, wherein the first end of the primary winding of the transformer module is connected to the current output terminal of the first power transistor switching module;

[0021] The second power transistor switching module has its current input terminal connected to the second end of the primary winding of the transformer module, and its current output terminal connected to the negative terminal of the DC bus.

[0022] The first gate drive module is used to receive the first raw drive signal and generate the first gate drive signal based on the first raw drive signal.

[0023] The second gate drive module is used to receive the second original drive signal and generate a second gate drive signal according to the second original drive signal; wherein the first gate drive signal and the second gate drive signal drive the first power transistor switch module and the second power transistor switch module to be turned on alternately.

[0024] The rectification and freewheeling module is connected to the secondary winding of the transformer module and is used to rectify and freewheel the voltage signal output by the transformer module.

[0025] In one embodiment, the power supply circuit further includes:

[0026] A voltage regulation module, connected to the rectification and freewheeling modules, is used to regulate the open-circuit voltage output by the rectification and freewheeling modules according to the input voltage control signal.

[0027] In one embodiment, the power supply circuit further includes:

[0028] An auxiliary step-down module, connected to the rectifier and freewheeling modules, is used to output an auxiliary voltage according to the input auxiliary power supply control signal.

[0029] In one embodiment, the first gate drive module includes: a first resistor, a second resistor, a first Zener diode, and a first capacitor;

[0030] The first end of the first resistor is connected to the positive terminal of the first original driving signal source. The second end of the first resistor and the first end of the second resistor are connected to the control terminal of the first power transistor circuit. The second end of the second resistor, the anode of the first Zener diode, and the first end of the first capacitor are connected to the negative terminal of the first original driving signal source. The cathode of the first Zener diode and the second end of the first capacitor are connected to the first end of the primary winding of the transformer module.

[0031] The second gate drive module includes: a third resistor, a fourth resistor, a second capacitor, and a second Zener diode;

[0032] The first end of the third resistor is connected to the positive terminal of the second original drive signal source. The second end of the third resistor and the first end of the fourth resistor are connected to the control terminal of the second power transistor module. The second end of the fourth resistor, the first end of the second capacitor, and the anode of the second Zener diode are connected to the negative terminal of the second original drive signal source. The cathode of the second Zener diode and the second end of the second capacitor are connected to the second end of the primary winding of the transformer module.

[0033] A third aspect of this application also provides a power supply device, the power supply device including the power supply circuit as described in any of the preceding claims.

[0034] A fourth aspect of this application also provides a welding machine, including a power supply circuit as described in any of the preceding embodiments.

[0035] This application provides a method for adjusting the open-circuit voltage of a power supply, a power supply circuit, a power supply device, and a welding machine. By alternately driving the first power transistor switching module and the second power transistor switching module to conduct, the transformer module operates in a state of extremely low energy density, thereby achieving the purpose of adjusting the open-circuit voltage of the power supply over a wide range. By using frequency hopping technology to reduce the equivalent driving frequency of the upper and lower switching transistors in the dual-transistor forward topology circuit of the power supply, the energy transfer density of the transformer is further reduced. The voltage regulation module controls the equivalent resistance of the power supply output terminal, and the auxiliary step-down module provides auxiliary voltage, thereby achieving the purpose of compound adjustment of the open-circuit voltage of the power supply. Finally, the rectification and freewheeling modules rectify and freewheel the voltage signal output by the transformer module. This solves the problem that the open-circuit voltage of existing welding power supplies is mostly not adjustable, or very rarely adjustable but with a small adjustment range, resulting in poor adaptability to welding processes. Attached Figure Description

[0036] Figure 1 A schematic diagram of a welding power source provided in this application;

[0037] Figure 2 A schematic diagram of another welding power source provided in this application;

[0038] Figure 3 A schematic diagram of a power supply circuit provided in an embodiment of this application;

[0039] Figure 4 This is a schematic diagram of another power supply circuit provided in an embodiment of this application;

[0040] Figure 5 This is a schematic diagram of another power supply circuit provided in an embodiment of this application;

[0041] Figure 6 This is a schematic diagram of another power supply circuit provided in an embodiment of this application. Detailed Implementation

[0042] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0043] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0044] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They 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, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0045] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0046] This application provides a first aspect of a method for adjusting the open-circuit voltage of a power supply. The power supply includes a first power transistor switching module, a transformer module, a second power transistor switching module, and a rectification and freewheeling module. The current input terminal of the first power transistor switching module is connected to the positive terminal of a DC bus, the current output terminal of the first power transistor switching module is connected to the first end of the primary winding of the transformer module, the current input terminal of the second power transistor switching module is connected to the second end of the primary winding of the transformer module, and the current output terminal of the second power transistor switching module is connected to the negative terminal of the DC bus.

[0047] Specifically, the open-circuit voltage adjustment method in this embodiment includes:

[0048] The first power transistor switching module and the second power transistor switching module are alternately turned on;

[0049] The voltage signal output by the transformer module is rectified and freewheeled by a rectification and freewheeling module; wherein the rectification and freewheeling module is connected to the secondary winding of the transformer module.

[0050] In this embodiment, the first power transistor switching module, the transformer module, and the second power transistor switching module form a two-transistor forward topology circuit. In regulating the open-circuit voltage of the power supply, by driving the upper and lower power transistors in the two-transistor forward topology circuit to conduct alternately, and utilizing the source-drain parasitic capacitance in the power transistors, the transformer module can operate in a state of extremely low energy transfer density. Thus, by controlling the main power switching transistors (the first power transistor switching module and the second power transistor switching module), the open-circuit voltage of the power supply can be adjusted over a wide range to achieve the optimal configuration of the output voltage.

[0051] In one embodiment, driving the first power transistor switching module and the second power transistor switching module to conduct alternately includes:

[0052] When the control terminal of the first power transistor switching module is set to a low-level signal, the control terminal of the second power transistor switching module is set to a high-level signal.

[0053] When the control terminal of the first power transistor switching module is set to a high-level signal, the control terminal of the second power transistor switching module is set to a low-level signal.

[0054] As an embodiment of this application, a first original drive signal source is used to provide a first gate drive signal to the control terminal of the first power transistor switching module, and a second original drive signal source is used to provide a second gate drive signal to the control terminal of the second power transistor switching module. By adjusting the level or duty cycle of the first gate drive signal and the second gate drive signal, the equivalent drive frequency of the first power transistor switching module and the second power transistor switching module can be adjusted. For example, if both the first power transistor switching module and the second power transistor switching module are N-type MOS transistors, in a specific application, if the first gate drive signal is a low-level signal, then the second gate drive signal is a high-level signal, and if the first gate drive signal is a high-level signal, then the second gate drive signal is a low-level signal.

[0055] Furthermore, a first gate drive module can be set between the first original drive signal source and the first power transistor switch module, and a second gate drive module can be set between the second original drive signal source and the second power transistor switch module, so that the first power transistor switch module and the second power transistor switch module can realize the negative voltage preset function during the alternating conduction process, so that the first power transistor switch module and the second power transistor switch module can have reliable negative voltage turn-off.

[0056] In one embodiment, driving the first power transistor switching module and the second power transistor switching module to conduct alternately includes: using frequency hopping technology to adjust the switching frequency of the first power transistor switching module and the second power transistor switching module to adjust the energy transfer density of the transformer module.

[0057] Specifically, in this embodiment, by adjusting the duty cycle of the first gate drive signal and the second gate drive signal using frequency hopping technology, the energy transfer density of the transformer module can be adjusted. For example, by using frequency hopping technology to reduce the equivalent drive frequency of the upper and lower switching transistors in the dual-transistor forward topology circuit of the power supply, the energy transfer density of the transformer can be further reduced. In this way, the open-circuit voltage can be controlled by the main power switching transistor to achieve a lower voltage, making it easier for the welding power supply to meet various safety requirements.

[0058] As an embodiment of this application, the open-circuit voltage adjustment method further includes: using a voltage regulation module to adjust the equivalent resistance of the output terminal of the power supply to regulate the open-circuit voltage of the power supply.

[0059] In this embodiment, by setting a voltage regulation module at the power output terminal, for example, by inserting an electronic switch in series with a constant resistance load connected in parallel at the output terminal of an existing welding power supply, the immutable "dead load" can be transformed into a variable "live load" through flexible control of the electronic switch. This achieves the function of a constant resistance load and, in the power supply's negative voltage preset operating mode, can drive the electronic switch with a PWM signal to control the equivalent resistance connected to the power output terminal, thereby lowering the open-circuit voltage and achieving the target adjustment of the open-circuit voltage. In one embodiment, this voltage regulation module can be an OVA circuit module.

[0060] As an embodiment of this application, the open-circuit voltage adjustment method further includes: using an auxiliary step-down module to output an auxiliary voltage according to the input auxiliary power supply control signal.

[0061] In this embodiment, an auxiliary step-down module is provided at the power output terminal. This auxiliary step-down module outputs an auxiliary voltage according to the input auxiliary power control signal. Furthermore, it can also sense changes in the output load. In addition, it can work in combination with the power supply's negative voltage preset mode to achieve the purpose of compound adjustment of the power supply's open-circuit voltage. In one embodiment, the auxiliary step-down module can be a VES circuit module.

[0062] As one embodiment of this application, see Figure 3As shown, the power supply circuit in this embodiment includes a first power transistor switching module 10, a transformer module 20, a second power transistor switching module 30, a first gate drive module 40, a second gate drive module 50, and a rectification and freewheeling module 60. Specifically, the current input terminal of the first power transistor switching module 10 is connected to the positive terminal VBUS+ of the DC bus; the first end of the primary winding of the transformer module 20 is connected to the current output terminal of the first power transistor switching module 10; the current input terminal of the second power transistor switching module 30 is connected to the second end of the primary winding of the transformer module 20, and the current output terminal of the second power transistor switching module 30 is connected to the negative terminal VBUS- of the DC bus; the first gate drive module 40 is used to receive the first original drive signal and generate the first gate drive signal according to the first original drive signal; the second gate drive module 50 is used to receive the second original drive signal and generate the second gate drive signal according to the second original drive signal; wherein, the first gate drive signal and the second gate drive signal can drive the first power transistor switching module 10 and the second power transistor switching module 30 to conduct alternately, respectively; the rectification and freewheeling module 60 is connected to the secondary winding of the transformer module 20 and is used to rectify and freewheel the voltage signal output by the transformer module 20.

[0063] In this embodiment, the first power transistor switching module 10, the transformer module 20, the second power transistor switching module 30, the first gate drive module 40, and the second gate drive module 50 constitute the inverter section of the dual-transistor forward topology circuit, which is used to convert the DC power supplied by the DC bus into AC power. In conjunction with the gate drive circuit with the function of generating negative voltage, i.e., the first gate drive module 40 and the second gate drive module 50, the first power transistor switching module 10 and the second power transistor switching module 30 can realize the negative voltage preset function during the alternating conduction process, so that the first power transistor switching module 10 and the second power transistor switching module 30 can achieve reliable negative voltage turn-off. Specifically, both the first power transistor switching module 10 and the second power transistor switching module 30 contain parasitic capacitance (e.g., drain-source parasitic capacitance). By driving the first power transistor switching module 10 and the second power transistor switching module 30 to conduct alternately, the transformer module 20 operates in a state of extremely low energy transfer density, and the maximum peak voltage of its secondary winding drops to about half of that during normal operation. This allows the open-circuit voltage of the welding power supply to be adjusted over a wide range by directly adjusting the switching frequency of the first power transistor switching module 10 and the second power transistor switching module 30. Furthermore, the optimal open-circuit arc-starting voltage can be easily applied according to the characteristics of different welding processes to achieve the optimal configuration of the arc-starting voltage.

[0064] As an embodiment of this application, frequency hopping technology can also be used to reduce the equivalent driving frequency of the upper and lower switching transistors in the dual-transistor forward topology circuit formed by the first power transistor switching module 10 and the second power transistor switching module 30, further reducing the average energy transfer density of the transformer module 20. This allows the open-circuit voltage to be controlled by the main power switching transistors (i.e., the first power transistor switching module 10 and the second power transistor switching module 30) to reach a lower voltage, making it easier for the welding power supply to meet various safety regulations. Specifically, the open-circuit voltage of the power supply circuit is adjusted by regulating the duty cycle of the first and second original driving signals.

[0065] In one embodiment, see Figure 4 As shown, the power supply circuit also includes a voltage regulation module 70, which is connected to the rectification and freewheeling module 60 and is used to regulate the open-circuit voltage output by the rectification and freewheeling module 60 according to the input voltage control signal.

[0066] In this embodiment, the open-circuit voltage output by the rectifier and freewheeling module 60 is adjusted by setting a voltage regulation module 70 and an input voltage control signal at the output of the power supply circuit. For example, the voltage regulation module 70 connected in parallel at the output of the power supply circuit can be composed of a resistive load and an electronic switch connected in series. By controlling the switching state of the electronic switch, the resistance of the power supply output is changed from an unadjustable "dead load" to an adjustable "live load." This not only achieves the function of a constant resistive load but also allows the welding power supply to control the switching frequency of the power switching transistor in the negative voltage preset working mode, thereby controlling the equivalent resistance connected to the output of the power supply circuit and lowering the open-circuit voltage, thus adjusting the open-circuit voltage. In one embodiment, the voltage control signal can be a PWM drive signal.

[0067] In one embodiment, see Figure 5 As shown, the power supply circuit also includes an auxiliary step-down module 80, which is used to output an auxiliary voltage according to the input auxiliary power control signal.

[0068] In this embodiment, the auxiliary step-down module 80 can input an auxiliary power control signal according to user needs, and then output an auxiliary voltage. This auxiliary voltage can be a safe voltage, for example, an auxiliary voltage of 36V.

[0069] In practical applications, the level of open-circuit voltage greatly affects the performance of arc initiation and arc stabilization. The higher the open-circuit voltage, the easier it is to initiate and stabilize the arc. Especially for some special welding processes, there are certain requirements for the open-circuit voltage. By using the auxiliary step-down module 80 to output auxiliary voltage, it is possible to switch between the open-circuit state and the welding working state. This not only ensures good arc initiation performance, but also effectively solves common problems that fail to meet safety regulations.

[0070] In a preferred embodiment of this application, the auxiliary step-down module 80 can also sense changes in the output load and output a corresponding open-circuit voltage based on these changes. Furthermore, it can be combined and worked in conjunction with the negative voltage preset mode of the power supply circuit to achieve a composite adjustment of the welding power supply's open-circuit voltage.

[0071] In one embodiment, see Figure 6 As shown, the first gate drive module 40 includes: a first resistor R1, a second resistor R2, a first Zener diode Z1, and a first capacitor C1; the first end of the first resistor R1 is connected to the positive terminal of the first original drive signal source, the second end of the first resistor R1 and the first end of the second resistor R2 are connected to the control terminal of the first power transistor module 10, the second end of the second resistor R2, the anode of the first Zener diode Z1 and the first end of the first capacitor C1 are connected to the negative terminal of the first original drive signal source, and the cathode of the first Zener diode Z1 and the second end of the first capacitor C1 are connected to the first end of the primary winding of the transformer module 20.

[0072] In this embodiment, the first gate drive module 40 is used to receive the first original drive signal Vgs1. The first original drive signal Vgs1 is adjusted by the negative voltage generating circuit composed of the gate resistor (i.e., the first resistor R1), the pull-down resistor (i.e., the second resistor R2), the first Zener diode Z1 and the first capacitor C1 to generate the first gate drive signal, so as to control the conduction and turn-off of the first power transistor switching module 10.

[0073] As one embodiment of this application, see Figure 6 As shown, the second gate drive module 50 includes: a third resistor R3, a fourth resistor R4, a second capacitor C2, and a second Zener diode Z2; the first end of the third resistor R3 is connected to the positive terminal of the second original drive signal source, the second end of the third resistor R3 and the first end of the fourth resistor R4 are connected to the control terminal of the second power transistor module 30, the second end of the fourth resistor R4, the first end of the second capacitor C2 and the anode of the second Zener diode Z2 are connected to the negative terminal of the second original drive signal source, and the cathode of the second Zener diode Z2 and the second end of the second capacitor C2 are connected to the second end of the primary winding of the transformer module 20.

[0074] In this embodiment, the second gate drive module 50 is used to receive the second original drive signal Vgs2. The second original drive signal Vgs2 is adjusted by the negative voltage generating circuit composed of the gate resistor (i.e., the third resistor R3), the pull-down resistor (i.e., the fourth resistor R4), the second Zener diode Z2, and the second capacitor C2 to generate the second gate drive signal, so as to control the conduction and turn-off of the second power transistor switching module 30.

[0075] As one embodiment of this application, see Figure 6 As shown, the first power transistor switching module 10 includes a first power transistor M1. The drain of the first power transistor M1 serves as the current input terminal of the first power transistor module 10 and is connected to the positive terminal VBUS+ of the DC bus. The source of the first power transistor M1 serves as the current output terminal of the first power transistor module 10 and is connected to the first end of the primary winding of the transformer module 20. The gate of the first power transistor M1 serves as the control terminal of the first power transistor module 10 and is connected to the first gate drive module 40.

[0076] As one embodiment of this application, see Figure 4 As shown, the second power transistor switching module 30 includes a second power transistor M2. The drain of the second power transistor M2 serves as the current input terminal of the second power transistor switching module 30 and is connected to the second end of the primary winding of the transformer module 20. The source of the second power transistor M2 serves as the current output terminal of the second power transistor module 30 and is connected to the negative terminal VBUS- of the DC bus. The gate of the second power transistor M2 serves as the control terminal of the second power transistor module 30 and is connected to the second gate drive module 50.

[0077] As an embodiment of this application, both the first power transistor M1 and the second power transistor M2 are N-type MOS transistors.

[0078] As one embodiment of this application, see Figure 6 As shown, the transformer module 20 includes a transformer T1, the primary winding of the transformer T1 serves as the primary winding of the transformer module 20, and the secondary winding of the transformer T1 serves as the secondary winding of the transformer module 20.

[0079] In this embodiment, the drain of the first power transistor M1 is connected to the positive terminal VBUS+ of the DC bus, the source of the first power transistor M1 is connected to the first end of the primary winding of the transformer T1, the drain of the second power transistor M2 is connected to the second end of the primary winding of the transformer T1, and the source of the second power transistor M2 is connected to the negative terminal VBUS- of the DC bus.

[0080] Ideally, current will flow through the primary winding of transformer T1 and drive transformer T1 to work only when the first power transistor M1 and the second power transistor M2 are turned on simultaneously. However, since there is a parasitic capacitance Cds between the drain and source terminals of the first power transistor M1 and the second power transistor M2, when either the first power transistor M1 or the second power transistor M2 is turned on alone, a circuit will be formed to charge the parasitic capacitance Cds through the primary winding of transformer T1. The circuit will not disappear until the parasitic capacitance Cds is fully charged. This process will also transfer energy to the secondary winding of transformer T1. For example, assume the on-resistance of the first power transistor M1 is Rds1, and its drain-source parasitic capacitance is Cds1; the on-resistance of the second power transistor M2 is Rds2, and its drain-source parasitic capacitance is Cds2; the first power transistor M1 and the second power transistor M2 operate in an alternating on-off manner. When the first power transistor M1 is on, the second power transistor M2 is off. This forms a charging circuit from the positive terminal VBUS+ of the DC bus, through Rds1, the primary winding of transformer T1, Cds2, to the negative terminal VBUS- of the DC bus. This circuit is close to zero. Cds1 is charged by the voltage, while Cds1 is rapidly discharged to near zero voltage by Rds1. When the second power transistor M2 is turned on, the first power transistor M1 is turned off. At this time, a charging circuit is formed from the positive terminal VBUS+ of the DC bus through Cds1, the primary winding of transformer T1, Rds2 to the negative terminal VBUS- of the DC bus. This charges Cds1, which was discharged to near zero voltage during the first power transistor M1's conduction. At the same time, Cds2 is rapidly discharged to near zero voltage by Rds2, preparing for the formation of a charging circuit when the first power transistor M1 is turned on. Since the charging process is completed instantaneously, and the charging current decreases as the voltage of Cds1 or Cds2 gradually increases, the energy transferred to the secondary winding of transformer T1 is much smaller than that under normal operating conditions when both upper and lower power transistors are conducting simultaneously. At the same time, the operating voltage of the primary winding of transformer T1 is also about 50% lower than under normal operating conditions. Therefore, the peak value of the secondary rectified output voltage is also about 50% lower than under normal operating conditions. Then, by adjusting the duty cycle of the gate drive signals of the first power transistor M1 and the second power transistor M2, the energy and voltage transferred to the secondary side of the transformer can be controlled.

[0081] Furthermore, the power supply circuit in the embodiment can also utilize frequency hopping technology to reduce the driving frequency of the gate drive signal, which can further reduce the energy density transmitted to the secondary side of the transformer, making the open-circuit voltage of the power supply easier to control and reducing power consumption, thereby achieving adjustment of the output open-circuit voltage.

[0082] As an embodiment of this application, in conjunction with a gate drive circuit that generates a negative voltage, the first power transistor M1 and the second power transistor M2 can achieve a negative voltage preset function during alternating conduction, enabling reliable negative voltage turn-off for both power transistors M1 and M2. For example, taking the drive circuit of the first power transistor M1 as an example, when the first original drive signal Vgs1 is high, it charges the gate-source capacitance Cgs1 of the first power transistor M1 through the first resistor R1. When the capacitance is charged to a level higher than the on-state voltage Vgsth of the first power transistor M1, the first power transistor M1 turns on. Simultaneously, the first capacitor C1 is also charged until it reaches the regulated voltage of the Zener diode connected in parallel. At this point, the source terminal of the first power transistor M1 is positive, and the Vgs1 terminal is negative. When Vgs1 goes low, Vgs1+ and Vgs1- are at the same potential, and the gate of the first power transistor M1 is at the same potential as Vgs1+. Since the voltage of the first capacitor C1 remains unchanged for a short time, the gate voltage of the first power transistor M1 is negative relative to the source of the first power transistor M1, and its amplitude is equal to the voltage across the first capacitor C1. The first power transistor M1 is turned off due to negative voltage. Therefore, the above-mentioned working mode in which the first power transistor M1 and the second power transistor M2 are alternately turned on is called the negative voltage preset mode in which the gate of the power transistor is set to negative voltage.

[0083] In one embodiment, see Figure 6 As shown, the rectification and freewheeling module 60 includes: a first diode D1, a second diode D2, and a first inductor L1; the anode of the first diode D1 is connected to the first end of the secondary winding of the transformer module 20, the cathode of the first diode D1 and the cathode of the second diode D2 are connected to the first end of the first inductor L1, the second end of the first inductor L1 serves as the positive output terminal of the power supply circuit, and the anode of the second diode D2 is connected to the second end of the secondary winding of the transformer module 20.

[0084] In this embodiment, the secondary winding of transformer T1, the rectifier diode (i.e., the first diode D1), the freewheeling diode (i.e., the second diode D2), and the output inductor (i.e., the first inductor L1) constitute the rectification and freewheeling sections of the two-transistor forward topology circuit. During the operation of transformer T1, the first diode D1 is forward-biased and the second diode D2 is reverse-biased and cut off, and the first inductor L1 is charged and stores energy. During the intermittent operation of transformer T1, the first diode D1 is reverse-biased and cut off, the second diode D2 is forward-biased and freewheels, and the first inductor L1 releases energy.

[0085] In one embodiment, see Figure 6As shown, the auxiliary step-down module 80 includes: a third diode D3, a fifth resistor R5, a first switching unit S1, and an auxiliary voltage source V1; the cathode of the third diode D3 is connected to the positive output terminal of the rectifier and freewheeling module 60, the anode of the third diode D3 is connected to the first terminal of the fifth resistor R5, the second terminal of the fifth resistor R5 is connected to the first terminal of the first switching unit S1, the second terminal of the first switching unit S1 is connected to the positive terminal of the auxiliary voltage source V1, and the negative terminal of the auxiliary voltage source V1 is connected to the negative output terminal of the rectifier and freewheeling module 60.

[0086] In this embodiment, the auxiliary step-down module 80 uses an independent safety voltage source (i.e., auxiliary voltage source V1) to output an open-circuit voltage (i.e., auxiliary voltage) that meets safety requirements. For example, the auxiliary step-down module 80 can be activated when an open-circuit voltage lower than DC 36V is required. The adjustment of the open-circuit voltage of the power supply circuit by the auxiliary step-down module 80 can be performed when the main power output circuit is turned off (e.g., the first power transistor M1 and the second power transistor M2 are turned off). That is, the auxiliary step-down module 80 can work independently based on the auxiliary voltage source V1 and the first switching unit S1, or it can work in conjunction with the negative voltage preset mode of the power supply circuit to achieve the purpose of compound adjustment of the open-circuit voltage of the welding power supply.

[0087] As one embodiment of the application, the first switching unit S1 can be a MOSFET, a bipolar junction transistor (BJT), a relay contact, etc.

[0088] In one embodiment, see Figure 6 As shown, the voltage regulation module 70 includes: a sixth resistor R6 and a second switching unit S2; the first end of the sixth resistor R6 is connected to the positive output terminal of the rectification and freewheeling module 60, the second end of the sixth resistor R6 is connected to the first end of the second switching unit S2, and the second end of the second switching unit S2 is connected to the negative output terminal of the rectification and freewheeling module 60.

[0089] In this embodiment, the voltage regulation module 70 can operate in two modes. One mode is to control the second switching unit S2 to be normally open, so that the sixth resistor R6 is used as a fixed load at the power output terminal. Then, in the negative voltage preset mode, the duty cycle of the gate drive signals of the first power transistor M1 and the second power transistor M2 is adjusted in a closed loop to achieve the purpose of regulating the open circuit voltage. The other mode is to preset a frequency number and a suitable duty cycle for the gate drive signals of the first power transistor M1 and the second power transistor M2 according to the target open circuit voltage. Then, the voltage control signal drives the second switching unit S2 to control the equivalent resistance connected to the power output terminal, thereby lowering the open circuit voltage and realizing the adjustment of the open circuit voltage.

[0090] As one embodiment of the application, the gate drive signals of the first power transistor M1 and the second power transistor M2 are pulse width modulation signals (PWM signals). The gate of the first power transistor M1 is connected to the first gate drive signal, and the gate of the second power transistor M2 is connected to the second gate drive signal. In the negative voltage preset mode, the open-circuit voltage of the power supply circuit can be automatically adjusted by adjusting the duty cycle of the first gate drive signal and the second gate drive signal through closed-loop adjustment.

[0091] Furthermore, as a preferred embodiment of this application, the voltage control signal used to control the switching state of the second switching unit S2 is a pulse width modulation signal. By adjusting the duty cycle of the voltage control signal, the switching frequency of the second switching unit S2 can be adjusted, thereby adjusting the equivalent resistance connected to the power supply output terminal, and thus realizing the adjustment of the open circuit voltage.

[0092] In one embodiment, see Figure 6 As shown, the second switching unit S2 includes an electronic switch. The first end of the electronic switch is connected to the second end of the sixth resistor R6. The second end of the electronic switch is connected to the negative output terminal of the rectifier and freewheeling module 60. The control terminal of the electronic switch is connected to a voltage control signal, which is used to control the switching state of the electronic switch.

[0093] As one embodiment of this application, the electronic switch can be a MOSFET, a bipolar junction transistor (BJT), a relay contact, etc.

[0094] This application also provides a power supply device, which includes a power supply circuit as described in any of the preceding claims.

[0095] This application also provides a welding machine, including a power supply circuit as described in any of the above embodiments.

[0096] In practice, the welding machine is an inverter welding machine, which can be loaded and used for welding.

[0097] This application's embodiments employ an innovative main power drive circuit and operating mode, novel VES (auxiliary step-down module 80) and OVA (voltage regulation module 70) modules, unique frequency hopping control technology, and open-circuit voltage software control strategies tailored to different welding process requirements. These multiple methods enable a wide range of adjustments to the welding power supply's open-circuit voltage, thereby solving the problems of existing welding power supplies failing to meet various safety regulations and different welding process requirements due to their inability to adjust or limited adjustment range. This achieves the effect of avoiding common safety compliance issues and realizing optimal configuration of arc initiation and arc stabilization voltages for different welding processes.

[0098] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0099] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0100] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0101] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0102] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method of adjusting an open circuit voltage of a power source, characterized by, The power supply includes a first power transistor switching module, a transformer module, a second power transistor switching module, and a rectification and freewheeling module. The current input terminal of the first power transistor switching module is connected to the positive terminal of the DC bus, the current output terminal of the first power transistor switching module is connected to the first end of the primary winding of the transformer module, the current input terminal of the second power transistor switching module is connected to the second end of the primary winding of the transformer module, and the current output terminal of the second power transistor switching module is connected to the negative terminal of the DC bus. The open-circuit voltage adjustment method includes: The first power transistor switching module and the second power transistor switching module are alternately turned on; Frequency hopping technology is used to adjust the switching frequencies of the first power transistor switching module and the second power transistor switching module to regulate the energy transfer density of the transformer module. Both the first and second power transistor switching modules include parasitic capacitances. When the first power transistor switching module is turned on, the first power transistor switching module... two When the first power transistor switching module is turned off, the second power transistor switching module is turned on when the first power transistor switching module is turned off in the next cycle. In the next cycle after that, the second power transistor switching module is turned off when the first power transistor switching module is turned on. This alternating on and off state is achieved so that the switching transistor and its parasitic capacitance can form a charging and discharging path. By alternating on and off, the parasitic capacitance charging and discharging circuit is activated, enabling the transformer to transfer a small amount of energy during non-working cycles. The voltage signal output from the transformer module is rectified and freewheeled through a rectification and freewheeling module; The rectifier and freewheeling module is connected to the secondary winding of the transformer module. The first original drive signal source is used to provide a first gate drive signal to the control terminal of the first power transistor switching module, and the second original drive signal source is used to provide a second gate drive signal to the control terminal of the second power transistor switching module. The equivalent drive frequency of the first power transistor switching module and the second power transistor switching module is adjusted by adjusting the level or duty cycle of the first gate drive signal and the second gate drive signal. A first gate drive module is provided between the first original drive signal source and the first power transistor switch module, and a second gate drive module is provided between the second original drive signal source and the second power transistor switch module, so that the first power transistor switch module and the second power transistor switch module can realize the negative voltage preset function during the alternating conduction process. In the negative voltage preset working mode, the equivalent resistance of the output terminal is controlled by controlling the switching frequency of the first power transistor switch module and the second power transistor switch module, thereby adjusting its open circuit voltage.

2. The open-circuit voltage adjustment method as described in claim 1, characterized in that, The open-circuit voltage adjustment method further includes: A voltage regulation module is used to adjust the equivalent resistance at the output terminal of the power supply in order to regulate the open-circuit voltage of the power supply.

3. The open-circuit voltage adjustment method as described in claim 1, characterized in that, The open-circuit voltage adjustment method further includes: An auxiliary step-down module is used to output an auxiliary voltage based on the input auxiliary power supply control signal.

4. A power supply circuit, characterized in that, The power supply circuit includes: The first power transistor switching module has its current input terminal connected to the positive terminal of the DC bus. A transformer module, wherein the first end of the primary winding of the transformer module is connected to the current output terminal of the first power transistor switching module; The second power transistor switching module has its current input terminal connected to the second end of the primary winding of the transformer module, and its current output terminal connected to the negative terminal of the DC bus. The first gate drive module is used to receive the first raw drive signal and generate the first gate drive signal based on the first raw drive signal. The second gate drive module receives a second original drive signal and generates a second gate drive signal based on the second original drive signal. The first and second gate drive signals drive the first and second power transistor switching modules to alternately conduct. By adjusting the levels or duty cycles of the first and second gate drive signals, the equivalent drive frequencies of the first and second power transistor switching modules are adjusted. The first and second gate drive modules enable the first and second power transistor switching modules to implement a negative voltage preset function during the alternating conduction process. In the negative voltage preset mode, the equivalent resistance at the output terminal is controlled by controlling the switching frequency of the first and second power transistor switching modules, thereby adjusting their open-circuit voltage. Both the first and second power transistor switching modules include parasitic capacitances. When the first power transistor switching module is on, the second gate drive signal... two When the first power transistor switching module is turned off, the second power transistor switching module is turned on when the first power transistor switching module is turned off in the next cycle. In the next cycle after that, the second power transistor switching module is turned off when the first power transistor switching module is turned on. This alternating on and off state is achieved so that the switching transistor and its parasitic capacitance can form a charging and discharging path. By alternating on and off, the parasitic capacitance charging and discharging circuit is activated, enabling the transformer to transfer a small amount of energy during non-working cycles. The rectification and freewheeling module is connected to the secondary winding of the transformer module and is used to rectify and freewheel the voltage signal output by the transformer module.

5. The power supply circuit as described in claim 4, characterized in that, The power supply circuit also includes: A voltage regulation module, connected to the rectification and freewheeling modules, is used to regulate the open-circuit voltage output by the rectification and freewheeling modules according to the input voltage control signal.

6. The power supply circuit as described in claim 4, characterized in that, The power supply circuit also includes: An auxiliary step-down module, connected to the rectifier and freewheeling modules, is used to output an auxiliary voltage according to the input auxiliary power supply control signal.

7. The power supply circuit as described in claim 4, characterized in that, The first gate drive module includes: a first resistor, a second resistor, a first Zener diode, and a first capacitor; The first end of the first resistor is connected to the positive terminal of the first original drive signal source. The second end of the first resistor and the first end of the second resistor are connected together to the control terminal of the first power transistor switching module. The second end of the second resistor, the anode of the first Zener diode, and the first end of the first capacitor are connected together to the negative terminal of the first original drive signal source. The cathode of the first Zener diode and the second end of the first capacitor are connected together to the first end of the primary winding of the transformer module. The second gate drive module includes: a third resistor, a fourth resistor, a second capacitor, and a second Zener diode; The first end of the third resistor is connected to the positive terminal of the second original drive signal source. The second end of the third resistor and the first end of the fourth resistor are connected to the control terminal of the second power transistor switching module. The second end of the fourth resistor, the first end of the second capacitor, and the anode of the second Zener diode are connected to the negative terminal of the second original drive signal source. The cathode of the second Zener diode and the second end of the second capacitor are connected to the second end of the primary winding of the transformer module.

8. A power supply device, characterized in that, The power supply device is used to perform the open-circuit voltage adjustment method as described in any one of claims 1-3, or includes the power supply circuit as described in any one of claims 4-7.

9. An electric welding machine, characterized in that, The welding machine is used to perform the open-circuit voltage adjustment method as described in any one of claims 1-3, or includes the power supply circuit as described in any one of claims 4-7.

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