A real-time measuring device for electron beam filament heating current

Abstract

The present invention relates to a real-time measurement device for electron beam filament heating current. The output end of a half-bridge inverter circuit is connected to the input end of a filament transformer. The output end of the filament transformer is respectively connected to the input end of a filament rectifier filter circuit and the input end of a power supply. The output end of the filament rectifier filter circuit is connected to a push-pull and isolation transformer sampling circuit. The power supply, oscillation circuit, and push-pull and isolation transformer sampling circuit are connected in sequence. The two primary windings of the isolation transformer in the push-pull and isolation transformer sampling circuit are complementary connected to the filament heating circuit and are used to obtain an AC sampling signal from the secondary winding of the isolation transformer after the collected filament heating current is stepped up and stepped down by the transformer. The AC sampling signal is then converted to DC and formed into a sampling voltage across a sampling resistor. The purpose of this real-time measurement device for electron beam filament heating current is to solve the problem of how to effectively and real-timely obtain an accurate filament heating current value.

Description

Technical Field

[0001] The invention relates to the technical field of electron beam welding equipment, and in particular to a real-time measuring device for electron beam filament heating current. Background Art

[0002] In existing hot cathode electron beam welding equipment, a filament heating power supply provides heating current to the cathode of the electron gun, heating the cathode tungsten filament and causing the electrons on its surface to generate a work function, putting it in a state of electron emission. The filament heating power supply typically uses an inverter circuit in series with a filament transformer for voltage reduction followed by rectification and filtering to achieve low-voltage, high-current output. The filament power supply output is connected to the accelerating power supply, with a voltage differential of -60 kV to ground. The filament inverter circuit is connected to the power grid, with a lower voltage differential to ground. Therefore, the two are isolated by the filament transformer, with an isolation voltage above -60 kV. The magnitude of the filament heating current determines the heating state of the cathode filament, directly affecting the precise controllable adjustment of the beam current and the service life of the cathode tungsten filament. Accurately measuring the filament current facilitates stable electron beam processing, enabling controllable adjustment of the electron beam current while maintaining the tungsten filament within its effective operating range, ensuring long-term filament use.

[0003] Because the high-voltage side of the filament heating power supply is suspended above the electron beam high-voltage acceleration power supply, with a voltage differential of -60kV to ground, conventional sampling methods are not feasible for real-time measurement of the heating current. Instead, we first measure the current at the inverter circuit output and infer the filament heating current value based on the transformer ratio. Secondly, in the absence of an accelerating voltage, we measure the correspondence between the filament setpoint signal and the actual filament current, and use this as the displayed filament current value under actual operating conditions.

[0004] Both of the above measurement methods use indirect methods to reflect the actual filament heating current value, so there is inaccuracy. In the method of reversely inferring the filament heating current through the transformer ratio and the primary current of the transformer, the primary current includes the excitation current of the filament transformer, so there is a certain error in the calculated result. The filament heating current measured and calibrated in the second method is the filament heating current in the non-working state, which is not the same value as the filament heating current in actual operation, so there is also a large error.

[0005] Therefore, the inventors provide a real-time measurement device for electron beam filament heating current. Summary of the Invention

[0006] (1) Technical problems to be solved

[0007] The embodiment of the present invention provides a real-time measurement device for electron beam filament heating current, which solves the technical problem of how to obtain an accurate filament heating current value effectively and in real time.

[0008] (2) Technical solution

[0009] The present invention provides a real-time measurement device for electron beam filament heating current, comprising a half-bridge inverter circuit, a filament transformer, a filament rectification and filtering circuit, a power supply, an oscillation circuit, and a push-pull and isolation transformer sampling circuit;

[0010] The output end of the half-bridge inverter circuit is connected to the input end of the filament transformer and is used to invert the DC voltage into an AC square wave voltage. The output end of the filament transformer is respectively connected to the input end of the filament rectifier filter circuit and the input end of the power supply. The output end of the filament rectifier filter circuit is connected to the push-pull and isolation transformer sampling circuit. The power supply, the oscillation circuit and the push-pull and isolation transformer sampling circuit are connected in sequence.

[0011] The two primary windings of the isolation transformer in the push-pull and isolation transformer sampling circuit are complementary connected to the filament heating circuit and are used to obtain an AC sampling signal on the secondary winding of the isolation transformer after the collected filament heating current is stepped up and stepped down by the transformer, and then formed into a DC sampling signal on the sampling resistor after being rectified by the rectifier circuit.

[0012] Furthermore, the half-bridge inverter circuit obtains the first AC voltage and the second AC voltage as input signals of the filament transformer by alternately switching the transistor M1 and the transistor M2; and adjusts the on-time of the transistor M1 and the transistor M2 to adjust the duty ratio of the output first AC voltage and the second AC voltage.

[0013] Furthermore, the filament transformer is used to step down the first AC voltage and the second AC voltage to obtain the first output signal and the second output signal.

[0014] Furthermore, the filament rectification and filtering circuit is used to receive the first output signal and the second output signal, and rectify them into DC through a full-bridge rectifier circuit, and then filter them into DC voltage by a filter circuit composed of LC to achieve heating of the filament.

[0015] Furthermore, the power supply is used to receive the first output signal and the second output signal, convert them into a DC voltage after passing through a full-bridge rectifier circuit, and then directly filter them through a filter capacitor to obtain a power supply voltage equivalent to the amplitude of the secondary output voltage of the filament transformer.

[0016] Furthermore, the oscillation circuit includes NE555, a resistor and a capacitor. When the power supply provides an operating voltage therefor, pin 3 of the NE555 will output a driving square wave to drive the push-pull and isolation transformer sampling circuit.

[0017] Furthermore, the push-pull and isolation transformer sampling circuit includes a push-pull circuit, a full-bridge rectifier circuit, a sampling resistor and an isolation transformer. The push-pull circuit is located on the primary winding side of the isolation transformer, the secondary winding of the isolation transformer is connected to the full-bridge rectifier circuit, and the sampling resistor is connected in parallel with the full-bridge rectifier circuit and is used to form a sampling signal.

[0018] Furthermore, the push-pull circuit includes a transistor Q1 and a transistor Q2, and the transistor Q1 and the transistor Q2 are configured to switch alternately under the action of a driving square wave.

[0019] Furthermore, when the driving signal is at a high level, the transistor Q1 is turned on and the transistor Q2 is turned off; when the driving signal is at a low level, the transistor Q1 is turned off and the transistor Q2 is turned on.

[0020] Furthermore, the oscillation circuit is used to output a square wave voltage with a duty cycle of 50%.

[0021] (3) Beneficial effects

[0022] In summary, the present invention connects a sampling transformer in series with the filament heating circuit, alternately switches the transformer's primary winding on and off via a switching tube, and connects the secondary winding to a sampling resistor, thereby converting the current in the filament heating circuit into a voltage signal and collecting it. This method enables real-time measurement of the filament current value during the electron beam processing state, unaffected by the equipment's operating state, and accurately measures the filament heating current value. The sampling transformer not only measures the filament heating current but also provides insulation isolation between the sampling signal and the filament heating current. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 This is a structural diagram of a device for real-time measurement of electron beam filament heating current provided by an embodiment of the present invention;

[0025] Figure 2 This is a structural schematic diagram of a half-bridge inverter circuit in a device for real-time measurement of electron beam filament heating current provided by an embodiment of the present invention;

[0026] Figure 3 This is a schematic structural diagram of a filament transformer in a real-time measurement device for electron beam filament heating current provided by an embodiment of the present invention;

[0027] Figure 4 This is a structural diagram of a filament rectification and filtering circuit in a real-time measurement device for electron beam filament heating current provided by an embodiment of the present invention;

[0028] Figure 5 This is a schematic structural diagram of a power supply in a device for real-time measurement of electron beam filament heating current provided by an embodiment of the present invention;

[0029] Figure 6 This is a schematic structural diagram of an oscillating circuit in a real-time measurement device for electron beam filament heating current provided by an embodiment of the present invention;

[0030] Figure 7 The present invention provides a schematic structural diagram of a push-pull and isolation transformer sampling circuit in a real-time measurement device for electron beam filament heating current.

[0031] In the picture:

[0032] 100-regulated DC power supply; 101-half-bridge inverter circuit; 102-filament transformer; 103-filament rectifier filter circuit; 201-power supply; 202-oscillation circuit; 203-push-pull and isolation transformer sampling circuit. DETAILED DESCRIPTION

[0033] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are intended to illustrate the principles of the present invention and are not intended to limit the scope of the present invention. That is, the present invention is not limited to the described embodiments and covers any modifications, replacements, and improvements to the parts, components, and connection methods without departing from the spirit of the present invention.

[0034] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0036] It should also be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "disposed" and "installed" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0037] Figure 1 1 is a schematic structural diagram of a device for real-time measurement of electron beam filament heating current provided by an embodiment of the present invention. The device may include a half-bridge inverter circuit 101, a filament transformer 102, a filament rectification and filtering circuit 103, a power supply 201, an oscillation circuit 202, and a push-pull and isolation transformer sampling circuit 203.

[0038] The output end of the half-bridge inverter circuit 101 is connected to the input end of the filament transformer 102 and is used to invert the DC voltage into an AC square wave voltage. The output end of the filament transformer 102 is respectively connected to the input end of the filament rectifier filter circuit 103 and the input end of the power supply 201. The output end of the filament rectifier filter circuit 103 is connected to the push-pull and isolation transformer sampling circuit 203. The power supply 201, the oscillation circuit 202 and the push-pull and isolation transformer sampling circuit 203 are connected in sequence; wherein,

[0039] The two primary windings of the isolation transformer in the push-pull and isolation transformer sampling circuit 203 are complementary connected to the filament heating circuit and are used to obtain an AC sampling signal on the secondary winding of the isolation transformer after the collected filament heating current is stepped up and stepped down by the transformer, and then formed into a DC sampling voltage on the sampling resistor after being rectified by the rectifier circuit.

[0040] In the above embodiment, the regulated DC power supply 100 is inverted into an AC square wave voltage with an adjustable duty cycle by the half-bridge inverter circuit 101, and after being stepped down by the filament transformer 102, it supplies power to the filament rectifier filter circuit 103 and the power supply 201 respectively; after passing through the filament rectifier filter circuit 103, an adjustable filament DC voltage is obtained to achieve filament heating; after passing through the power supply 201, a power supply voltage equivalent to the amplitude of the secondary output voltage of the filament transformer is obtained to achieve power supply to the oscillation circuit 202; the oscillation circuit 202 outputs a square wave voltage to drive the transistors in the push-pull and isolation transformer sampling circuit 203 to achieve alternating switching; the two primary windings of the isolation transformer in the push-pull and isolation transformer sampling circuit 203 are complementary connected to the filament heating circuit to achieve the collection of the filament heating current; after the current is stepped up and down by the transformer, an AC sampling signal is obtained on the secondary winding, and after being rectified into DC by the rectifier circuit, a sampling voltage is formed on the sampling resistor. The actual filament heating current value is inferred based on the transformer ratio and the sampling resistance value, realizing real-time measurement and monitoring of the filament heating current when the electron beam equipment is in working state.

[0041] As an optional implementation, the half-bridge inverter circuit 101 obtains the first AC voltage and the second AC voltage by alternately switching transistors M1 and M2 as input signals of the filament transformer; and adjusts the on-time of transistors M1 and M2 to adjust the duty cycle of the output first AC voltage and the second AC voltage.

[0042] Specifically, if Figure 2 As shown, half-bridge inverter circuit 101 inverts the input voltage of regulated DC power supply 100 into an AC square wave. By alternating switching M1 and M2, AC voltages AC1 and AC2 are generated, serving as input signals for the filament transformer. By adjusting the on-time of M1 and M2, the duty cycle of the output AC voltages AC1 and AC2 can be adjusted. Since the specific structure of half-bridge inverter circuit 101 is conventional, it will not be described in detail here.

[0043] As an optional implementation, the filament transformer 102 is configured to step down the first AC voltage and the second AC voltage to obtain the first output signal and the second output signal.

[0044] Specifically, if Figure 3 As shown, the filament transformer 102 steps down the input signals AC1 and AC2 to obtain output signals AC11 and AC21. Since the specific structure of the filament transformer 102 is conventional, it will not be described in detail here.

[0045] As an optional embodiment, the filament rectification and filtering circuit 103 is used to receive the first output signal and the second output signal, and rectify them into DC through a full-bridge rectifier circuit, and then filter them into DC voltage by a filter circuit composed of LC to achieve heating of the filament.

[0046] Specifically, if Figure 4 As shown, filament rectification and filtering circuit 103 receives the output voltages AC11 and AC21 from filament transformer 102 and rectifies them into DC via a full-bridge rectifier circuit. This DC voltage is then filtered into a DC voltage by a filter circuit composed of LC components to heat the filaments. The specific structure of filament rectification and filtering circuit 103 is conventional and will not be described in detail here.

[0047] As an optional embodiment, the power supply 201 is used to receive the first output signal and the second output signal, convert them into a DC voltage after passing through a full-bridge rectifier circuit, and then directly filter them through a filter capacitor to obtain a power supply voltage equivalent to the amplitude of the secondary output voltage of the filament transformer 102.

[0048] Specifically, if Figure 5As shown, power supply 201 receives the output voltages AC11 and AC21 from filament transformer 102, converts them into a DC voltage through a full-bridge rectifier circuit, and then directly filters them through a filter capacitor to obtain a supply voltage equivalent to the amplitude of the secondary output voltage of filament transformer 102. This value is not affected by changes in the duty cycle, and therefore the voltage is relatively stable. The specific structure of power supply 201 is conventional and will not be described in detail here.

[0049] As an optional implementation, the oscillation circuit 202 includes NE555, a resistor and a capacitor. When the power supply 201 provides an operating voltage thereto, pin 3 of the NE555 will output a driving square wave to drive the push-pull and isolation transformer sampling circuit 203 .

[0050] Specifically, if Figure 6 As shown, oscillator circuit 202 is composed of NE555 (8-pin time-base integrated circuit) and resistors and capacitors. When power supply 201 provides operating voltage, pin 3 of NE555 will output a driving square wave with a duty cycle of approximately 50%, which is used to drive push-pull and isolation transformer sampling circuit 203. Since the specific structure of oscillator circuit 202 is conventional, it will not be described in detail here.

[0051] As an optional implementation, the push-pull and isolation transformer sampling circuit 203 includes a push-pull circuit, a full-bridge rectifier circuit, a sampling resistor and an isolation transformer. The push-pull circuit is located on the primary winding side of the isolation transformer, the secondary winding of the isolation transformer is connected to the full-bridge rectifier circuit, and the sampling resistor is connected in parallel with the full-bridge rectifier circuit and is used to form a sampling signal.

[0052] Specifically, if Figure 7 As shown, the push-pull and isolation transformer sampling circuit 203 alternately switches transistor Q1 and transistor Q2 under the action of the driving square wave. When the driving signal is at a high level, Q1 is turned on and Q2 is turned off. At this time, winding T2A is connected to the filament heating circuit to sample the current; when the driving signal is at a low level, Q2 is turned on and Q1 is turned off. At this time, winding T2B is connected to the filament heating circuit to sample the heating current; after the sampling signal is coupled to the secondary winding T2C, it is rectified into DC by the full-bridge rectifier circuit and forms a sampling signal on the sampling resistor R4.

[0053] As an optional embodiment, oscillator circuit 202 is configured to output a square wave voltage with a 50% duty cycle. The duty cycle refers to the proportion of a signal's high level to its period; a 50% duty cycle means the high level and low level each occupy half the time. When pin 3 outputs a high level, Q1 turns on and Q2 turns off. When the output is a low level, Q1 turns off and Q2 turns on. This ensures that the conduction durations of Q1 and Q2 are consistent, ensuring that the primary winding of the isolated sampling transformer receives the AC input voltage for the same amount of time. Otherwise, the transformer will become magnetized and inoperable.

[0054] In summary, the process of the real-time measurement device for electron beam filament heating current is as follows: the regulated DC power supply 100 is converted into an AC square wave voltage with a fixed amplitude and an adjustable duty cycle under the action of the half-bridge inverter circuit 101. After the voltage is stepped down by the filament transformer 102, the voltage is supplied to the filament rectification and filtering circuit 103 and the power supply 201 respectively; after the action of the filament rectification and filtering circuit 103, an adjustable DC voltage is obtained to achieve heating of the filament; after the action of the power supply 201, the output voltage of the secondary side of the filament transformer 102 is The oscillator circuit 202 receives its supply voltage, which starts operating and outputs a pulse drive signal, driving the push-pull and isolation transformer sampling circuit 203. Transistors Q1 and Q2 of the push-pull and isolation transformer sampling circuit 203 alternately switch on and off, allowing the isolation transformer primary windings T2A and T2B to alternately connect to the filament heating circuit. The heating current is sampled and converted to DC by the secondary winding T2C, which is then rectified by a full-bridge rectifier circuit. Ultimately, a real-time sampling signal of the filament heating current is obtained on the sampling resistor R4. By measuring the voltage across the sampling resistor R4 and using the transformation ratio of the sampling transformer, the sampled signal value can be converted into the filament heating current value.

[0055] It should be noted that the various embodiments in this specification are described in a progressive manner. References to the same or similar parts between the various embodiments are sufficient. Each embodiment focuses on the differences from the other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and technologies are omitted here.

[0056] The above are merely embodiments of the present application and are not intended to limit the present application. Various modifications and variations are possible for those skilled in the art without departing from the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A real-time measurement device for electron beam filament heating current, characterized in that: It comprises a half-bridge inverter circuit (101), a filament transformer (102), a filament rectification and filtering circuit (103), a power supply (201), an oscillation circuit (202), and a push-pull and isolation transformer sampling circuit (203); The output end of the half-bridge inverter circuit (101) is connected to the input end of the filament transformer (102) and is used to invert a DC voltage into an AC square wave voltage. The output end of the filament transformer (102) is respectively connected to the input end of the filament rectification and filtering circuit (103) and the input end of the power supply (201). The output end of the filament rectification and filtering circuit (103) is connected to the push-pull and isolation transformer sampling circuit (203). The power supply (201), the oscillation circuit (202) and the push-pull and isolation transformer sampling circuit (203) are connected in sequence. The two primary windings of the isolation transformer in the push-pull and isolation transformer sampling circuit (203) are complementary connected to the filament heating circuit and are used to obtain an AC sampling signal on the secondary winding of the isolation transformer after the collected filament heating current is stepped up and stepped down by the transformer, and then formed into a DC sampling signal on the sampling resistor after being rectified by the rectifier circuit.

2. The device for real-time measurement of electron beam filament heating current according to claim 1, characterized in that: The half-bridge inverter circuit (101) obtains a first AC voltage and a second AC voltage as input signals of a filament transformer by alternately switching transistors M1 and M2; and adjusts the on-time of the transistors M1 and M2 to adjust the duty ratio of the output first AC voltage and the second AC voltage.

3. The device for real-time measurement of electron beam filament heating current according to claim 2, characterized in that: The filament transformer (102) is used for reducing the first AC voltage and the second AC voltage to obtain a first output signal and a second output signal.

4. The device for real-time measurement of electron beam filament heating current according to claim 3, characterized in that: The filament rectification and filtering circuit (103) is used to receive the first output signal and the second output signal, and rectify them into direct current through a full-bridge rectification circuit, and then filter them into a direct current voltage through a filtering circuit composed of LC to achieve heating of the filament.

5. The device for real-time measurement of electron beam filament heating current according to claim 3, characterized in that: The power supply (201) is used to receive the first output signal and the second output signal, convert them into a DC voltage after passing through a full-bridge rectifier circuit, and then directly filter them through a filter capacitor to obtain a power supply voltage equivalent to the secondary output voltage amplitude of the filament transformer (102).

6. The device for real-time measurement of electron beam filament heating current according to claim 1, characterized in that: The oscillation circuit (202) includes NE555, a resistor and a capacitor. When the power supply (201) provides an operating voltage for the oscillation circuit, pin 3 of the NE555 will output a driving square wave to drive the push-pull and isolation transformer sampling circuit (203).

7. The device for real-time measurement of electron beam filament heating current according to claim 1, characterized in that: The push-pull and isolation transformer sampling circuit (203) comprises a push-pull circuit, a full-bridge rectifier circuit, a sampling resistor and an isolation transformer, wherein the push-pull circuit is located on the primary winding side of the isolation transformer, the secondary winding of the isolation transformer is connected to the full-bridge rectifier circuit, and the sampling resistor is connected in parallel with the full-bridge rectifier circuit and is used to form a sampling signal.

8. The device for real-time measurement of electron beam filament heating current according to claim 7, characterized in that: The push-pull circuit includes a transistor Q1 and a transistor Q2, and the transistor Q1 and the transistor Q2 are used to switch alternately under the action of a driving square wave.

9. The device for real-time measurement of electron beam filament heating current according to claim 8, characterized in that: When the driving signal is at a high level, the transistor Q1 is turned on and the transistor Q2 is turned off; when the driving signal is at a low level, the transistor Q1 is turned off and the transistor Q2 is turned on.

10. The device for real-time measurement of electron beam filament heating current according to any one of claims 1 to 9, characterized in that: The oscillation circuit (202) is used to output a square wave voltage with a duty cycle of 50%.

Images