CN113691148A - Current direction switching circuit, welding machine driving circuit and welding machine equipment - Google Patents
Current direction switching circuit, welding machine driving circuit and welding machine equipment Download PDFInfo
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- CN113691148A CN113691148A CN202110959170.2A CN202110959170A CN113691148A CN 113691148 A CN113691148 A CN 113691148A CN 202110959170 A CN202110959170 A CN 202110959170A CN 113691148 A CN113691148 A CN 113691148A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/10—Other electric circuits therefor; Protective circuits; Remote controls
- B23K9/1006—Power supply
- B23K9/1043—Power supply characterised by the electric circuit
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
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- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Dc-Dc Converters (AREA)
- Inverter Devices (AREA)
Abstract
The invention provides a current direction switching circuit, a welding machine driving circuit and welding machine equipment, wherein the current direction switching circuit comprises a full-bridge rectifying circuit, a switching circuit and a control circuit, the control circuit controls each switch of the switching circuit to be correspondingly switched on or switched off when the current of an output inductor is smaller than a preset current value, a first-direction current loop formed by a first secondary winding, the first switch and the output end of the current direction switching circuit is switched to a second-direction current loop formed by a second secondary winding, the output end of the current direction switching circuit and a second switch, so that bidirectional voltage is provided for a welding machine body, and the current loop in each direction only passes through one switch, so that the power consumption is reduced.
Description
Technical Field
The invention belongs to the technical field of power supplies, and particularly relates to a current direction switching circuit, a welding machine driving circuit and welding machine equipment.
Background
At present, when a welding machine is used, bidirectional voltage is needed for some welding, namely, the direction of current output is changed, and the load has the resistance characteristic, so that the output voltage is positive and negative bidirectional voltage, and the influence of a metal oxide layer on the welding effect in the welding process is reduced.
The traditional switching circuit adds a secondary inverter circuit consisting of VT 1-VT 4 after a primary inverter rectifier bridge to carry out direction conversion, and realizes the change of the positive and negative output polarities according to different opening combinations of VT 1-VT 4. As shown in fig. 1, VT 1-VT 4 work at low frequency to control the polarity of output; the primary inverted full bridge works at high frequency to control the output voltage and current.
The working voltage of the secondary inverter circuit is low, the selected switching devices are generally MOS tubes, and the working current is generally larger, so that a plurality of MOS tubes are required to be connected in parallel for use.
When the switching circuit works, a current loop passes through two diagonal semiconductor devices, such as VT1 and VT4, or VT2 or VT3, and the number of the semiconductor devices participating in current transmission is larger, so that the power consumption is increased.
Disclosure of Invention
The invention aims to provide a current direction switching circuit, aiming at reducing the power consumption generated by the switching circuit.
A first aspect of an embodiment of the present invention provides a current direction switching circuit, where the current direction switching circuit is correspondingly connected to a transformer and an output inductor, the transformer is connected to a full-bridge inverter circuit, and the current direction switching circuit includes:
the input end of the full-bridge rectifying circuit is correspondingly connected with the first end of the first secondary winding and the second end of the second secondary winding of the transformer, wherein the second end of the first secondary winding, the first end of the second secondary winding and the first end of the output inductor of the transformer are connected in common, and the second end of the output inductor forms the first output end of the current direction switching circuit;
the switch circuit comprises a first switch, a second switch, a third switch and a fourth switch, wherein the first end of the first switch, the first end of the fourth switch and the first power output end of the full-bridge rectification circuit are connected in common, the second end of the first switch and the second end of the second switch are connected in common to form the second output end of the current direction switching circuit, the first end of the second switch, the first end of the fourth switch and the second power output end of the full-bridge rectification circuit are connected in common, the second end of the third switch is connected with the second end of the second secondary winding, and the second end of the fourth switch is connected with the first end of the first secondary winding;
the control circuit is respectively connected with the full-bridge inverter circuit, the switch circuit and the output inductor correspondingly, the control circuit triggers and controls when the current of the output inductor is smaller than a preset current value, each switch in the switch circuit is correspondingly switched on and off to switch the current direction of the output inductor, wherein before switching, the first switch and the second switch are mutually in a switched-on state and a switched-off state, and before switching, the third switch and the fourth switch are in a switched-off state.
In one embodiment, the control circuit is specifically configured to:
when the voltage between the first output end and the second output end of the current direction switching circuit is negative and the current of the output inductor is smaller than a preset current value, controlling the second switch and the third switch to be switched on and controlling the first switch to be switched off;
after the current of the output inductor reverses, controlling the third switch to be switched off; or
When the voltage between the first output end and the second output end of the current direction switching circuit is positive and the current of the output inductor is smaller than a preset current value, controlling the first switch and the fourth switch to be switched on and controlling the second switch to be switched off;
and after the current of the output inductor is reversed, controlling the fourth switch to be switched off.
In one embodiment, the control circuit triggers the current direction switching operation when the current of the output inductor is smaller than a preset current value and the full-bridge inverter circuit operates in a follow current state.
In one embodiment, the full-bridge rectification circuit includes a first diode, a second diode, a third diode, and a fourth diode;
the first end of the first diode, the first end of the third diode and the first end of the first secondary winding are connected in common, the first end of the second diode, the first end of the fourth diode and the second end of the second secondary winding are connected in common, the second end of the first diode, the second end of the second diode and the first end of the first switch are connected in common, and the second end of the third diode, the second end of the fourth diode and the first end of the second switch are connected in common.
In one embodiment, the full-bridge inverter circuit comprises a first electronic switch tube, a second electronic switch tube, a third electronic switch tube and a fourth electronic switch tube;
the first end of the first electronic switch tube and the first end of the third electronic switch tube are connected in common to form the positive power input end of the full-bridge inverter circuit, the first end of the second electronic switch tube and the first end of the fourth electronic switch tube are connected in common to form the negative power input end of the full-bridge inverter circuit, the second end of the first electronic switch tube, the second end of the second electronic switch tube and the first end of the primary winding of the transformer are connected in common, the second end of the third electronic switch tube, the second end of the fourth electronic switch tube and the second end of the primary winding are connected in common, and the control circuit is specifically used for:
when the voltage between the first output end and the second output end of the current direction switching circuit is negative, the current of the output inductor is smaller than a preset current value, and the second electronic switch tube and the third electronic switch tube are in a follow current state, controlling the second switch and the third switch to be switched on and controlling the first switch to be switched off;
after the current of the output inductor reverses, controlling the third switch to be switched off; or
When the voltage between a first output end and a second output end of the current direction switching circuit is positive, the current of the output inductor is smaller than a preset current value, and the first electronic switching tube and the fourth electronic switching tube are in a follow current state, controlling the first switch and the fourth switch to be switched on and controlling the second switch to be switched off;
and after the current of the output inductor is reversed, controlling the fourth switch to be switched off.
In one embodiment, the control circuit includes a controller and a current sampling circuit connected to the output inductor and the controller, respectively.
In one embodiment, the current direction switching circuit further comprises a first filter circuit connected in parallel between the first output terminal and the second output terminal of the current direction switching circuit.
The second aspect of the embodiment of the invention provides a welding machine driving circuit, which comprises a full-bridge inverter circuit, a transformer, an output inductor and the current direction switching circuit, wherein the full-bridge inverter circuit, the transformer and the output inductor are sequentially connected, and the current direction switching circuit is correspondingly connected with the transformer.
In one embodiment, the current direction switching circuit further comprises a second filter circuit connected in parallel between the input ends of the full-bridge inverter circuit.
A third aspect of embodiments of the present invention provides welder apparatus comprising a welder body and a welder drive circuit as described above.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: by adopting the full-bridge rectification circuit, the current direction switching circuit is formed by the switch circuit and the control circuit, when the current of the output inductor is smaller than a preset current value, the control circuit controls the corresponding connection or disconnection of the switches of the switch circuit, the current loop in the first direction formed by the output ends of the first secondary winding, the first switch and the current direction switching circuit is switched to the current loop in the second direction formed by the output ends of the second secondary winding, the current direction switching circuit and the second switch, thereby providing bidirectional voltage for the welding machine body, the current loop in each direction only passes through one switch, and the power consumption is reduced.
Drawings
FIG. 1 is a schematic circuit diagram of a conventional switching circuit;
fig. 2 is a schematic circuit structure diagram of a current direction switching circuit according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention 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 merely illustrative of the invention and are not intended to limit the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
A first aspect of the embodiments of the present invention provides a current direction switching circuit 100.
As shown in fig. 2, the current direction switching circuit 100 is correspondingly connected to a transformer T1 and an output inductor L1, a transformer T1 is connected to a full-bridge inverter circuit 200, the full-bridge inverter circuit 200 includes four electronic switching tubes for inverting an input dc power into a high-voltage ac power, a transformer T1 includes a primary winding, a first secondary winding and a second secondary winding, and a transformer T1 is configured to step down the high-voltage ac power into a low-voltage ac power, wherein a second end of the first secondary winding, a first end of the second secondary winding, and a first end of an output inductor L1 of the transformer T1 are connected in common, a second end of the output inductor L1 forms a first output end of the current direction switching circuit 100, and the current direction switching circuit 100 and the output inductor L1 are configured to connect to a welding machine body to implement bidirectional current output.
To implement current direction switching, the current direction switching circuit 100 includes:
the input end of the full-bridge rectifying circuit 10 is correspondingly connected with the first end of the first secondary winding and the second end of the second secondary winding of the transformer T1;
a switch circuit 20, the switch circuit 20 including a first switch S1, a second switch S2, a third switch S3 and a fourth switch S4, a first end of the first switch S1 and a first end of the fourth switch S4 being commonly connected to the first power output terminal of the full-bridge rectifier circuit 10, a second end of the first switch S1 and a second end of the second switch S2 being commonly connected to form a second output terminal of the current direction switching circuit 100, a first end of the second switch S2 and a first end of the fourth switch S4 being commonly connected to the second power output terminal of the full-bridge rectifier circuit 10, a second end of the third switch S3 being connected to a second end of the second secondary winding, and a second end of the fourth switch S4 being connected to the first end of the first secondary winding;
and the control circuit is correspondingly connected with the full-bridge inverter circuit 200, the switch circuit 20 and the output inductor L1 respectively, and triggers and controls the corresponding on and off of each switch in the switch circuit 20 when the current of the output inductor L1 is smaller than a preset current value so as to switch the current direction of the output inductor L1, wherein the first switch S1 and the second switch S2 are in an on state and an off state before switching, and the third switch S3 and the fourth switch S4 are in an off state before switching.
In this embodiment, the first switch S1 and the second switch S2 are connected in common and cooperate with the output inductor L1 to form a power output end of the current direction switching circuit 100, wherein the first switch S1 and the second switch S2 are used to realize the current direction of the output inductor L1, so as to change the polarity of the working voltage of the welder body, in a normal working state, the first switch S1 and the second switch S2 are in an on-off state, that is, when the first switch is turned on, the second switch S2 is turned off, the third switch S3 and the fourth switch S4 are used to assist in current commutation, and in a normal working state, the third switch S3 and the fourth switch S4 are kept in an off state.
When the first switch S1 is turned on, the first secondary winding, the upper arm of the full-bridge rectifier circuit 10, the first switch S1, the power output terminal of the current direction switching circuit 100, and the output inductor L1 form a current loop in the first direction, a voltage difference between the first power output terminal and the second power output terminal of the current direction switching circuit 100 is negative, when the second switch S2 is turned on, the second secondary winding, the output inductor L1, the power output terminal of the current direction switching circuit 100, and the second switch S2 form a current loop in the second direction, and a voltage difference between the first power output terminal and the second power output terminal of the current direction switching circuit 100 is positive.
The polarity change depends on the switching state switching of the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4, and is triggered when the current of the output inductor L1, namely the output current of the current direction switching circuit 100, is smaller than a preset current value, so that the current direction switching is completed in one period, the control circuit monitors the current of the output inductor L1 in real time, and controls the corresponding on and off of each switch under a set condition, so that the current loop in the first direction is switched to the current loop in the second direction, and bidirectional voltage is provided for the welding machine body.
The current loop in each direction only passes through one first switch S1 or one second switch S2, so that the power consumption is reduced, meanwhile, different switch structures can be adopted for the switches according to the magnitude of the working current, for example, a plurality of MOS (metal oxide semiconductor) tubes are connected in parallel, and the specific structure is not limited.
Specifically, in one embodiment, the control circuit is specifically configured to:
when the voltage between the first output terminal and the second output terminal of the current direction switching circuit 100 is negative and the current of the output inductor L1 is smaller than the preset current value, controlling the second switch S2 and the third switch S3 to be turned on and controlling the first switch S1 to be turned off;
after the current of the output inductor L1 reverses, the third switch S3 is controlled to turn off; or
When the voltage between the first output end and the second output end of the current direction switching circuit 100 is positive and the current of the output inductor L1 is smaller than the preset current value, controlling the first switch S1 and the fourth switch S4 to be turned on and controlling the second switch S2 to be turned off;
after the current of the output inductor L1 is reversed, the fourth switch S4 is controlled to be turned off.
Assuming that the first switch S1 is turned on and the second switch S2 is turned off before the current direction is switched, the upper bridge arm of the full-bridge rectification circuit 10 is in a working state, the voltage difference between the first power output end and the second power output end of the current direction switching circuit 100 is negative, when the current of the output inductor L1 is detected to be smaller than the preset current value, the control circuit triggers the current switching operation, and meanwhile, in order to avoid that the secondary current affects the working states of the switches of the full-bridge inverter circuit 200 and reduce power consumption during the switching process, the switching operation occurs in the freewheeling state of the full-bridge inverter circuit 200, that is, when the electronic switching tubes of the full-bridge inverter circuit 200 are in the off state.
When the switching starts, the second switch S2 and the third switch S3 are turned on, because the current of the primary winding is zero, the first secondary winding and the second secondary winding equally divide the inductive current, and after the third switch S3 and the fourth switch S4 are turned on, the current of the second secondary winding is distributed by the upper bridge arm and the third switch S3 connected to the full-bridge rectifier circuit 10 according to the line impedance, and meanwhile, when the second switch S2 and the third switch S3 are turned on, the inductive current keeps the original path, and the turn-on voltage is approximately zero, so that the turn-on loss of the second switch S2 and the third switch S3 is low.
After the second switch S2 and the third switch S3 are turned on, the first switch S1 is controlled to be turned off, the current flowing through the first secondary winding loses a path, the inductive current all flows through the second secondary winding, the third switch S3 and the second switch S2, the current direction is reversed, the control circuit controls the third switch S3 to be turned off after detecting that the current is reversed, the lower arm connected with the second secondary winding is put into operation, and the current loop in the first direction is switched to the current loop in the second direction to be completed.
Or before the current direction is switched, the second switch S2 is turned on, the first switch S1 is turned off, the lower bridge arm of the full-bridge rectification circuit 10 is in an operating state, the voltage difference between the first power output end and the second power output end of the current direction switching circuit 100 is positive, when the current of the output inductor L1 is detected to be smaller than a preset current value, the control circuit triggers the current switching operation, meanwhile, in order to avoid that the secondary current affects the operating states of the switches of the full-bridge inverter circuit 200 and reduce power consumption during the switching process, the switching operation occurs in the follow current state of the full-bridge inverter circuit 200, that is, when the electronic switching tubes of the full-bridge inverter circuit 200 are in the off state.
When the switching starts, the first switch S1 and the fourth switch S4 are turned on, because the current of the primary winding is zero, the first secondary winding and the second secondary winding equally divide the inductive current, after the first switch S1 and the fourth switch S4 are turned on, the current of the first secondary winding is distributed by the lower bridge arm and the fourth switch S4 connected with the full-bridge rectifier circuit 10 according to the line impedance, and meanwhile, when the first switch S1 and the fourth switch S4 are turned on, the inductive current keeps the original path, and the turn-on voltage is approximately zero, so that the turn-on loss of the first switch S1 and the fourth switch S4 is low.
After the first switch S1 and the fourth switch S4 are switched on, the second switch S2 is controlled to be switched off, the current flowing through the second secondary winding loses a path, the inductive current all flows through the first secondary winding, the fourth switch S4 and the first switch S1, the current direction is reversed, the control circuit controls the fourth switch S4 to be switched off after detecting that the current is reversed, the upper bridge arm connected with the first secondary winding is put into operation, and the current loop in the second direction is switched to the current loop in the first direction to be completed.
The first switch and the second switch for current conversion are used for participating in work when the output current is small and quit work in a switching period, the effective value of the flowing current is small, and the devices of small current can be selected, so that the purposes of saving cost and power consumption are achieved.
The current direction switching circuit 100 feeds the current of the output inductor L1 back to the input end, so that a power resistor for consuming capacitor voltage is omitted, and the efficiency is higher.
Wherein the full-bridge rectifier circuit 10 may include a rectifier bridge or a rectifier circuit composed of diodes, as shown in fig. 2, in one embodiment, the full-bridge rectifier circuit 10 includes a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4;
a first end of the first diode D1, a first end of the third diode D3 and a first end of the first secondary winding are commonly connected, a first end of the second diode D2, a first end of the fourth diode D4 and a second end of the second secondary winding are commonly connected, a second end of the first diode D1, a second end of the second diode D2 and a first end of the first switch S1 are commonly connected, and a second end of the third diode D3, a second end of the fourth diode D4 and a first end of the second switch S2 are commonly connected.
Further, in one embodiment, the full-bridge inverter circuit 200 includes a first electronic switch Q1, a second electronic switch Q2, a third electronic switch Q3, and a fourth electronic switch Q4;
the first end of the first electronic switch tube Q1 and the first end of the third electronic switch tube Q3 are connected in common to form a positive power input end of the full-bridge inverter circuit 200, the first end of the second electronic switch tube Q2 and the first end of the fourth electronic switch tube Q4 are connected in common to form a negative power input end of the full-bridge inverter circuit 200, the second end of the first electronic switch tube Q1, the second end of the second electronic switch tube Q2 and the first end of the primary winding of the transformer T1 are connected in common, the second end of the third electronic switch tube Q3, the second end of the fourth electronic switch tube Q4 and the second end of the primary winding are connected in common, and the control circuit is specifically configured to:
when the voltage between the first output end and the second output end of the current direction switching circuit 100 is negative, the current of the output inductor L1 is smaller than a preset current value, and the second electronic switch Q2 and the third electronic switch Q3 are in a freewheeling state, the second switch S2 and the third switch S3 are controlled to be turned on, and the first switch S1 is controlled to be turned off;
after the current of the output inductor L1 reverses, the third switch S3 is controlled to turn off; or
When the voltage between the first output end and the second output end of the current direction switching circuit 100 is positive, the current of the output inductor L1 is smaller than a preset current value, and the first electronic switch Q1 and the fourth electronic switch Q4 are in a freewheeling state, controlling the first switch S1 and the fourth switch S4 to be turned on and controlling the second switch S2 to be turned off;
after the current of the output inductor L1 is reversed, the fourth switch S4 is controlled to be turned off.
In this embodiment, it is assumed that before the current direction is switched, the first switch S1 is turned on, the second switch S2 is turned off, the first diode D1 and the second diode D2 of the full-bridge rectifier circuit 10 are in an operating state, the voltage difference between the first power output terminal and the second power output terminal of the current direction switching circuit 100 is negative, when the current of the output inductor L1 is detected to be smaller than the preset current value, the control circuit triggers the current switching operation, and meanwhile, in order to avoid the secondary current from affecting the operating states of the switches of the full-bridge inverter circuit 200 during the switching process and reduce the power consumption, the switching operation occurs in the freewheeling states of the second electronic switch Q2 and the third electronic switch S3 of the full-bridge inverter circuit 200, that is, the second electronic switch Q2 and the third electronic switch Q3 are turned off until the first electronic switch Q1 and the fourth electronic switch Q4 are turned on, the first electronic switch Q1, the second switch S2, the second switch D, The second electronic switch Q2, the third electronic switch Q3 and the fourth electronic switch Q4 are all in an off state.
When the switching starts, the second switch S2 and the third switch S3 are turned on, because the current of the primary winding is zero, the first secondary winding and the second secondary winding equally divide the inductive current, and after the third switch S3 and the fourth switch S4 are turned on, the current of the second secondary winding is distributed by the second diode D2 and the third switch S3 connected to the full-bridge rectifier circuit 10 according to the line impedance, and meanwhile, when the second switch S2 and the third switch S3 are turned on, the inductive current keeps the original path, and the turn-on voltage is approximately zero, so the turn-on loss of the second switch S2 and the third switch S3 is low.
After the second switch S2 and the third switch S3 are turned on, the first switch S1 is controlled to be turned off, the current flowing through the first secondary winding loses a path, the inductor current all flows through the second secondary winding, the third switch S3 and the second switch S2, the current flowing through the second secondary winding is induced to the primary winding to generate a current, the current flows back to the input through the body diodes of the first electronic switch Q1 and the fourth electronic switch Q4, the output inductor L1 is excited by the input voltage of the full-bridge inverter circuit 200 in the direction opposite to the current flow, the inductor current is gradually reduced, because the output inductor L1 is large, the inductor current cannot be suddenly reduced to zero, when the current flow of the second electronic switch Q2 and the third electronic switch Q3 is finished, and the first electronic switch Q1 and the fourth electronic switch Q4 are turned on, the currents of the first electronic switch Q1 and the fourth electronic switch Q4 are still input to the body diodes, the first electronic switch tube Q1 and the fourth electronic switch tube Q4 can realize zero-voltage turn-on.
After the first electronic switch tube Q1 and the fourth electronic switch tube Q4 are turned on, the excitation direction of the output inductor L1 is unchanged, the current of the output inductor L1 continues to decrease, when the current decreases to a value that the arc cannot be maintained, the arc is extinguished, the current of the output inductor L1 is in an open-circuit state, the output inductor L1 generates high voltage to re-ignite the arc, and the inductor current starts to increase reversely.
When the current is switched, the current flows through the third switch S3 completely, when the current is reversed, the fourth bridge arm connected with the second secondary winding is put into operation, the control circuit detects that the current is reversed, the control circuit controls the third switch S3 to be turned off, and the current loop in the first direction is switched to the current loop in the second direction to be completed.
Similarly, before the current direction is switched, the second switch S2 is turned on, the first switch S1 is turned off, the third diode D3 and the fourth diode D4 of the full-bridge rectification circuit 10 are in an operating state, the voltage difference between the first power output end and the second power output end of the current direction switching circuit 100 is positive, when the current of the output inductor L1 is detected to be smaller than a preset current value, the control circuit triggers the current switching operation, meanwhile, in order to avoid that the secondary current affects the operating states of the switches of the full-bridge inverter circuit 200 during the switching process, and reduce the power consumption, the switching operation occurs in the freewheeling state of the full-bridge inverter circuit 200, that is, when the electronic switching tubes operating in the full-bridge inverter circuit 200 are in an off state.
When the switching is started, the first switch S1 and the fourth switch S4 are turned on, because the current of the primary winding is zero, the first secondary winding and the second secondary winding equally divide the inductive current, after the first switch S1 and the fourth switch S4 are turned on, the current of the first secondary winding is distributed by the third diode D3 and the fourth switch S4 connected to the full-bridge rectifier circuit 10 according to the line impedance, and meanwhile, when the first switch S1 and the fourth switch S4 are turned on, the inductive current keeps the original path, and the turn-on voltage is approximately zero, so the turn-on loss of the first switch S1 and the fourth switch S4 is low.
After the first switch S1 and the fourth switch S4 are turned on, the second switch S2 is controlled to be turned off, the current flowing through the second secondary winding loses a path, and the inductor current all flows through the first secondary winding, the fourth switch S4 and the first switch S1.
The current flows through the first secondary winding, is induced to the primary winding to generate a current, and flows back to the input through the body diodes of the second electronic switch tube Q2 and the third electronic switch tube Q3, the output inductor L1 is excited by the input voltage of the full-bridge inverter circuit 200 in the opposite direction of the current flow, and the inductor current gradually decreases because the output inductor L1 is large, the inductor current does not suddenly drop to zero, and when the follow current of the first electronic switch tube Q1 and the fourth electronic switch tube Q4 is finished, and the second electronic switch tube Q2 and the third electronic switch tube Q3 are turned on, the current still flows into the body diodes of the second electronic switch tube Q2 and the third electronic switch tube Q3, and therefore, the zero-voltage turn-on can be realized by the second electronic switch tube Q2 and the third electronic switch tube Q3.
After the second electronic switching tube Q2 and the third electronic switching tube Q3 are turned on, the excitation direction of the output inductor L1 is unchanged, the current of the output inductor L1 continues to decrease, when the current decreases to a level where the arc cannot be maintained, the arc is extinguished, the current of the output inductor L1 is in an open-circuit state, the output inductor L1 generates high voltage to re-ignite the arc, and the inductor current starts to increase reversely.
When the current is switched, the current completely flows through the fourth switch S4, when the current is reversed, the first diode D1 connected with the first secondary winding is put into operation, the control circuit controls the fourth switch S4 to be switched off after detecting that the current is reversed, and the current loop in the second direction is switched to the current loop in the first direction to be completed.
The control circuit can adopt a controller and a corresponding sampling circuit, in one embodiment, the control circuit comprises a controller and a current sampling circuit, the current sampling circuit is respectively connected with the output inductor L1 and the controller, the current sampling circuit can adopt a current divider or a current Hall sensor and is connected with the first end or the second end corresponding to the output inductor L1 so as to detect the magnitude and the direction of the current of the output inductor L1, and the control circuit correspondingly controls the on-off of the first switch S1 to the fourth switch S4 according to a sampling signal fed back by the current sampling circuit, so that the current direction switching is realized, and further, bidirectional voltage is provided for the welding machine body.
As shown in fig. 2, in order to improve the output efficiency and reduce noise, in one embodiment, the current direction switching circuit 100 further includes a first filter circuit connected in parallel between the first output terminal and the second output terminal of the current direction switching circuit 100, wherein the first filter circuit includes a capacitor C1.
The current direction switching circuit 100 has few high-power devices, and can use a radiator with smaller volume, thereby reducing the volume and the cost of the whole welding machine.
The present invention further provides a welder driving circuit, which includes a full-bridge inverter circuit 200, a transformer T1, an output inductor L1, and a current direction switching circuit 100, where the specific structure of the current direction switching circuit 100 refers to the above embodiments, and the welder driving circuit adopts all technical solutions of all the above embodiments, so that the welder driving circuit at least has all the beneficial effects brought by the technical solutions of the above embodiments, and details are not repeated here. The full-bridge inverter circuit 200, the transformer T1 and the output inductor L1 are connected in sequence, and the current direction switching circuit 100 is correspondingly connected to the transformer T1.
In this embodiment, the current direction switching circuit 100 is correspondingly connected to the transformer T1 and the output inductor L1, the transformer T1 is connected to the full-bridge inverter circuit 200, the full-bridge inverter circuit 200 includes four electronic switching tubes for inverting and converting an input dc power into a high-voltage ac power, the transformer T1 includes a primary winding, a first secondary winding and a second secondary winding, the transformer T1 is configured to step-down convert the high-voltage ac power into a low-voltage ac power, wherein a second end of the first secondary winding, a first end of the second secondary winding, and a first end of the output inductor L1 of the transformer T1 are connected in common, a second end of the output inductor L1 forms a first output end of the current direction switching circuit 100, and the current direction switching circuit 100 and the output inductor L1 are configured to connect to a welding machine body to implement bidirectional current output.
Further, in order to reduce the input noise, in one embodiment, the current direction switching circuit 100 further includes a second filter circuit (not shown) connected in parallel between the input terminals of the full-bridge inverter circuit 200.
The present invention further provides a welder device, which includes a welder body and a welder driving circuit, and the specific structure of the welder driving circuit refers to the above embodiments.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. The utility model provides a current direction switching circuit, current direction switching circuit corresponds with transformer and output inductance and is connected, the transformer is connected with full-bridge inverter circuit, its characterized in that, current direction switching circuit includes:
the input end of the full-bridge rectifying circuit is correspondingly connected with the first end of the first secondary winding and the second end of the second secondary winding of the transformer, wherein the second end of the first secondary winding, the first end of the second secondary winding and the first end of the output inductor of the transformer are connected in common, and the second end of the output inductor forms the first output end of the current direction switching circuit;
the switch circuit comprises a first switch, a second switch, a third switch and a fourth switch, wherein the first end of the first switch, the first end of the fourth switch and the first power output end of the full-bridge rectification circuit are connected in common, the second end of the first switch and the second end of the second switch are connected in common to form the second output end of the current direction switching circuit, the first end of the second switch, the first end of the fourth switch and the second power output end of the full-bridge rectification circuit are connected in common, the second end of the third switch is connected with the second end of the second secondary winding, and the second end of the fourth switch is connected with the first end of the first secondary winding;
the control circuit is respectively connected with the full-bridge inverter circuit, the switch circuit and the output inductor correspondingly, the control circuit triggers and controls when the current of the output inductor is smaller than a preset current value, each switch in the switch circuit is correspondingly switched on and off to switch the current direction of the output inductor, wherein before switching, the first switch and the second switch are mutually in a switched-on state and a switched-off state, and before switching, the third switch and the fourth switch are in a switched-off state.
2. The current direction switching circuit of claim 1, wherein the control circuit is specifically configured to:
when the voltage between the first output end and the second output end of the current direction switching circuit is negative and the current of the output inductor is smaller than a preset current value, controlling the second switch and the third switch to be switched on and controlling the first switch to be switched off;
after the current of the output inductor reverses, controlling the third switch to be switched off; or
When the voltage between the first output end and the second output end of the current direction switching circuit is positive and the current of the output inductor is smaller than a preset current value, controlling the first switch and the fourth switch to be switched on and controlling the second switch to be switched off;
and after the current of the output inductor is reversed, controlling the fourth switch to be switched off.
3. The current direction switching circuit according to claim 2, wherein the control circuit triggers the current direction switching operation when the current of the output inductor is smaller than a preset current value and the full-bridge inverter circuit operates in a freewheeling state.
4. The current direction switching circuit according to claim 3, wherein the full-bridge rectification circuit includes a first diode, a second diode, a third diode, and a fourth diode;
the first end of the first diode, the first end of the third diode and the first end of the first secondary winding are connected in common, the first end of the second diode, the first end of the fourth diode and the second end of the second secondary winding are connected in common, the second end of the first diode, the second end of the second diode and the first end of the first switch are connected in common, and the second end of the third diode, the second end of the fourth diode and the first end of the second switch are connected in common.
5. The current direction switching circuit according to claim 4, wherein the full-bridge inverter circuit comprises a first electronic switch tube, a second electronic switch tube, a third electronic switch tube and a fourth electronic switch tube;
the first end of the first electronic switch tube and the first end of the third electronic switch tube are connected in common to form the positive power input end of the full-bridge inverter circuit, the first end of the second electronic switch tube and the first end of the fourth electronic switch tube are connected in common to form the negative power input end of the full-bridge inverter circuit, the second end of the first electronic switch tube, the second end of the second electronic switch tube and the first end of the primary winding of the transformer are connected in common, the second end of the third electronic switch tube, the second end of the fourth electronic switch tube and the second end of the primary winding are connected in common, and the control circuit is characterized in that:
when the voltage between the first output end and the second output end of the current direction switching circuit is negative, the current of the output inductor is smaller than a preset current value, and the second electronic switch tube and the third electronic switch tube are in a follow current state, controlling the second switch and the third switch to be switched on and controlling the first switch to be switched off;
after the current of the output inductor reverses, controlling the third switch to be switched off; or
When the voltage between a first output end and a second output end of the current direction switching circuit is positive, the current of the output inductor is smaller than a preset current value, and the first electronic switching tube and the fourth electronic switching tube are in a follow current state, controlling the first switch and the fourth switch to be switched on and controlling the second switch to be switched off;
and after the current of the output inductor is reversed, controlling the fourth switch to be switched off.
6. The current direction switching circuit according to any one of claims 1 to 5, wherein the control circuit comprises a controller and a current sampling circuit, and the current sampling circuit is connected with the output inductor and the controller respectively.
7. The current direction switching circuit of claim 6, further comprising a first filter circuit connected in parallel between the first output terminal and the second output terminal of the current direction switching circuit.
8. A welding machine driving circuit is characterized by comprising a full-bridge inverter circuit, a transformer, an output inductor and the current direction switching circuit as claimed in any one of claims 1 to 7, wherein the full-bridge inverter circuit, the transformer and the output inductor are sequentially connected, and the current direction switching circuit is correspondingly connected with the transformer.
9. The welder drive circuit of claim 8, wherein the current direction switching circuit further comprises a second filter circuit connected in parallel between the input terminals of the full bridge inverter circuit.
10. A welder apparatus, characterized by comprising a welder body and a welder drive circuit as in claim 9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110959170.2A CN113691148A (en) | 2021-08-20 | 2021-08-20 | Current direction switching circuit, welding machine driving circuit and welding machine equipment |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110959170.2A CN113691148A (en) | 2021-08-20 | 2021-08-20 | Current direction switching circuit, welding machine driving circuit and welding machine equipment |
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| CN113691148A true CN113691148A (en) | 2021-11-23 |
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| CN114221556A (en) * | 2021-12-14 | 2022-03-22 | 哈尔滨工业大学 | AC-DC hybrid multi-port electric energy router and control method thereof |
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