阅读说明：本技术 一种感应加热器电路结构及应用 (Induction heater circuit structure and application ) 是由 张闯 李欣泽 金亮 刘素贞 于 2020-12-25 设计创作，主要内容包括：本发明为一种感应加热器电路结构及应用,包括电阻R-1～R-4、感应线圈、电感L-3、二极管D-1～D-2、电容C-1、MOS管Q-1～Q-2和电源B-1；电源B-1的正极与电感L-3的一端、电阻R-3的一端和电阻R-4的一端连接,电感L-3的另一端与感应线圈的中部连接；MOS管Q-1的栅极与电阻R-3的另一端、电阻R-1的一端、二极管D-1的正极连接,二极管D-1的负极与感应线圈的一端连接；MOS管Q-1的源极与电源B-1的负极连接,MOS管Q-1的漏极与感应线圈的另一端连接；电阻R-1的另一端与电源B-1的负极连接；MOS管Q-2的栅极与电阻R-4的另一端、二极管D-2的正极、电阻R-2的一端连接。能够用于野外工作环境,电源接通后自动激发交流电。(The invention relates to an induction heater circuit structure and application, comprising a resistor R 1 ～R 4 An induction coil and an inductor L 3 Diode D 1 ～D 2 Capacitor C 1 MOS transistor Q 1 ～Q 2 And a power supply B 1 (ii) a Power supply B 1 Positive electrode and inductor L 3 One terminal of (1), resistance R 3 And a resistor R 4 Is connected to an inductor L 3 The other end of the first coil is connected with the middle part of the induction coil; MOS tube Q 1 Gate and resistor R of 3 Another terminal of (1), a resistor R 1 One terminal of (1), diode D 1 Is connected to the anode of diode D 1 The negative electrode of the induction coil is connected with one end of the induction coil; MOS tube Q 1 Source and power supply B 1 Is connected with the negative electrode of the MOS transistor Q 1 Drain electrode and induction coil ofThe other end of the first and second connecting rods is connected; resistance R 1 Another end of (1) and a power supply B 1 The negative electrode of (1) is connected; MOS tube Q 2 Gate and resistor R of 4 Another terminal of (1), diode D 2 Positive electrode and resistance R 2 Is connected at one end. The device can be used in the field working environment, and the alternating current can be automatically excited after the power supply is switched on.)

1. An induction heater circuit structure, characterized in that the circuit structure comprises a resistor R₁～R₄An induction coil and an inductor L₃Diode D₁～D₂Capacitor C₁MOS transistor Q₁～Q₂And a power supply B₁；

The power supply B₁Positive electrode and inductor L₃One terminal of (1), resistance R₃And a resistor R₄Is connected to an inductor L₃The other end of the first coil is connected with the middle part of the induction coil;

MOS tube Q₁Gate and resistor R of₃Another terminal of (1), a resistor R₁One terminal of (1), diode D₁Is connected to the anode of diode D₁The negative electrode of the induction coil is connected with one end of the induction coil; MOS tube Q₁Source and power supply B₁Is connected with the negative electrode of the MOS transistor Q₁The drain electrode of the inductor is connected with the other end of the induction coil; resistance R₁Another end of (1) and a power supply B₁The negative electrode of (1) is connected;

MOS tube Q₂Gate and resistor R of₄Another terminal of (1), diode D₂Positive electrode and resistance R₂Is connected to a resistor R₂Another end of the MOS transistor Q₂Source and power supply B₁Is connected with the negative electrode of the MOS transistor Q₂Drain electrode of (2) and induction coil and diode D₁One end of the negative electrode is connected with the other end of the negative electrode; diode D₂Negative electrode and induction coil and MOS tube Q₁One end connected with the drain electrode of the transistor is connected with the drain electrode of the transistor; capacitor C₁In parallel with the induction coil.

2. The induction heater circuit configuration of claim 1, wherein said capacitance C₁Is a variable capacitor.

3. The tunable induction heater of claim 1, wherein the induction coil is a spiral coil or a helmholtz coil; when the coil is a Helmholtz coil, the metal piece to be tested is placed in the Helmholtz coil.

4. The induction heater circuit configuration of claim 1, wherein the resistance R₁And R₂Are all 10k omega, and the resistance R₃And R₄Is 470k omega.

5. The induction heater circuit configuration of claim 1, wherein power supply B₁The voltage amplitude of the voltage is 10-40V.

6. Use of an induction heater using the circuit configuration of claim 1, wherein the induction heater is capable of inducing current flow in a strain clamp for uniform heating of the strain clamp in a field environment.

Technical Field

The invention belongs to the technical field of induction heating, and particularly relates to a circuit structure of an induction heater and application thereof.

Background

The strain clamp is used as an important component of an overhead line, and is used for fixing a lead, bearing the tension of the lead and bearing the load current of the line. The strain clamp is an electric conductor, and the crimping quality of the strain clamp is the premise of ensuring the safe and reliable operation of the overhead line.

The crimping quality of the strain clamp usually adopts a vernier caliper to measure whether the opposite side distance of the steel tube after being pressed and the opposite side distance of the aluminum tube after being pressed meet the installation requirements, and the quality defect of the crimping is very easy to occur because the quality problem inside the crimping position can not be found through the vernier caliper and the appearance inspection.

Eddy current thermal imaging detection is a novel nondestructive detection technology, based on the infrared radiation principle, the quality of a workpiece is judged by scanning, recording or observing the temperature field change of the surface of the detected workpiece, and the temperature field of the surface of the detected workpiece is mainly caused by different heat transfer rules to a deep layer due to workpiece defects or internal structure discontinuity.

Because overhead line is most in open-air environment, in order to realize the hot formation of image of the vortex of strain clamp and detect, but this application has designed a frequency modulation induction heater, through carrying out induction heating to strain clamp, form the vortex on strain clamp, the heat transmits on strain clamp, observes strain clamp's temperature field through image detection and can learn its crimping quality.

Disclosure of Invention

In view of the deficiencies of the prior art, the present invention provides an induction heater circuit structure and application thereof.

The technical scheme adopted by the invention for solving the technical problems is as follows:

an induction heater circuit structure, characterized in that the circuit structure comprises a resistor R₁～R₄An induction coil and an inductor L₃Diode D₁～D₂Capacitor C₁MOS transistor Q₁～Q₂And a power supply B₁；

The power supply B₁Positive electrode and inductor L₃One terminal of (1), resistance R₃And a resistor R₄Is connected to an inductor L₃The other end of the first coil is connected with the middle part of the induction coil;

MOS tube Q₁Gate and resistor R of₃Another terminal of (1), a resistor R₁One terminal of (1), diode D₁Is connected to the anode of diode D₁The negative electrode of the induction coil is connected with one end of the induction coil; MOS tube Q₁Source and power supply B₁Is connected with the negative electrode of the MOS transistor Q₁The drain electrode of the inductor is connected with the other end of the induction coil; resistance R₁Another end of (1) and a power supply B₁The negative electrode of (1) is connected;

MOS tube Q₂Gate and resistor R of₄Another terminal of (1), diode D₂Positive electrode and resistance R₂Is connected to a resistor R₂Another end of the MOS transistor Q₂Source and power supply B₁Is connected with the negative electrode of the MOS transistor Q₂Drain electrode of (2) and induction coil and diode D₁One end of the negative electrode is connected with the other end of the negative electrode; diode D₂Negative electrode and induction coil and MOS tube Q₁One end connected with the drain electrode of the transistor is connected with the drain electrode of the transistor; capacitor C₁In parallel with the induction coil.

The capacitor C₁Is a variable capacitor.

The induction coil is a spiral coil or a Helmholtz coil; when the coil is a Helmholtz coil, the metal piece to be tested is placed in the Helmholtz coil.

The resistor R₁And R₂Are all 10k omega, and the resistance R₃And R₄Is 470k omega.

The power supply B₁Voltage amplitude of10-40V.

The invention also provides application of the induction heater using the circuit structure, which is characterized in that the induction heater can be used in a field environment to enable the strain clamp to form induction current so as to uniformly heat the strain clamp.

Compared with the prior art, the invention has the beneficial effects that:

1. the circuit of the invention has simple structure and few components, so the whole induction heater has small volume and is convenient to carry and more suitable for field working environment; after the power supply is switched on, the circuit automatically excites the alternating current, no additional control is needed, and the use is more convenient.

2. Experiments prove that the circuit structure can generate stable and controllable sine alternating current on the induction coil, the output is stable, the strain clamp can be uniformly heated, stable eddy current is formed on the strain clamp, and the measurement error is reduced.

3. The strain clamp of different models has different thickness, therefore the skin degree of depth is different, so add variable capacitor in the circuit, can reach the purpose of control skin degree of depth, can satisfy the heating demand of different metalworks of waiting to detect.

4. The induction coil adopts a Helmholtz coil with an open structure, so that the metal piece to be detected can be conveniently taken and placed; the Helmholtz coil is different from the traditional coil in that a pair of identical current-carrying coils are parallel and coaxial with each other, when alternating current passes through the current-carrying coils, when the distance between the two current-carrying coils is equal to the radius of the Helmholtz coil, the total magnetic field of the two current-carrying coils is uniform in a large range near the middle point of the axis of the Helmholtz coil, and uniform alternating current is favorably generated.

Drawings

FIG. 1 is a schematic diagram of the present invention;

fig. 2 is a voltage waveform diagram of points a, b and c in fig. 1.

Detailed Description

The technical solutions of the present invention are described in detail below with reference to specific drawings and embodiments, and are not intended to limit the scope of the present invention.

The invention relates to an induction heater circuit structure (referring to fig. 1-2 for short), comprising a resistor R₁～R₄An induction coil and an inductor L₃Diode D₁～D₂Capacitor C₁MOS transistor Q₁～Q₂And a power supply B₁；

The power supply B₁Positive electrode and inductor L₃One terminal of (1), resistance R₃And a resistor R₄Is connected to an inductor L₃The other end of the first coil is connected with the middle part of the induction coil;

MOS tube Q₁Gate and resistor R of₃Another terminal of (1), a resistor R₁One terminal of (1), diode D₁Is connected to the anode of diode D₁The negative electrode of the induction coil is connected with one end of the induction coil; MOS tube Q₁Source and power supply B₁Is connected with the negative electrode of the MOS transistor Q₁The drain electrode of the inductor is connected with the other end of the induction coil; resistance R₁Another end of (1) and a power supply B₁The negative electrode of (1) is connected;

MOS tube Q₂Gate and resistor R of₄Another terminal of (1), diode D₂Positive electrode and resistance R₂Is connected to a resistor R₂Another end of the MOS transistor Q₂Source and power supply B₁Is connected with the negative electrode of the MOS transistor Q₂Drain electrode of (2) and induction coil and diode D₁One end of the negative electrode is connected with the other end of the negative electrode; diode D₂Negative electrode and induction coil and MOS tube Q₁One end connected with the drain electrode of the transistor is connected with the drain electrode of the transistor; capacitor C₁In parallel with the induction coil.

The resistor R₁And R₂The resistance values of the MOS transistor are all 10k omega, and the MOS transistor can be reliably turned off; for example, due to the resistance R₁So that the MOS transistor Q₁Gate to power supply B₁The voltage drop exists between the cathodes, thereby avoiding the MOS tube Q₁Grid electrode of (2) is directly connected with a power supply B₁The negative electrode of the MOS transistor is connected to ensure that the MOS transistor Q is reached₁The start-up voltage of (c).

Resistance R₃And R₄The resistance values of the MOS transistors are all 470k omega, the gate current of the MOS transistors is limited,the current passing through the MOS tube is prevented from being overlarge, and the MOS tube is prevented from being punctured.

Power supply B₁The voltage amplitude of the voltage is 10-40V.

The capacitor C₁Is a variable capacitor.

The induction coil can be a spiral coil, a Helmholtz coil and the like; the Helmholtz coil is preferably selected, the structure of the Helmholtz coil is in an open state, the metal piece to be detected is conveniently placed into the coil, the shape of the metal piece to be detected does not need to be considered, and the Helmholtz coil is wider in applicability.

The working principle and the working process of the invention are as follows:

for convenience of describing the circuit principle, the induction coil is equivalent to two identical inductors L₁And L₂(ii) a Let points a, b, c, d, e be MOS transistors Q respectively₂Point on drain, inductance L₃Connection point with induction coil and MOS tube Q₁Point on drain, MOS transistor Q₁Point on grid, MOS tube Q₂A point on the gate.

Power supply B₁After switching on, the supply voltages flow through the inductors L respectively₃、L₁MOS transistor Q₁And an inductance L₃、L₂MOS transistor Q₁Make the MOS transistor Q₁And Q₂And conducting, wherein the potential at the point b is greater than the potentials at the points a and c, the potential at the point d is greater than the potential at the point a, and the potential at the point e is greater than the potential at the point c.

Due to the discreteness of element parameters, such as the discreteness of parameters of the MOS tubes, the difference of the routing lengths and the like, the current flowing into the two MOS tubes is different in magnitude; supposing to flow through MOS transistor Q₁Current of greater than MOS transistor Q₂So that a current flows through the inductance L₁Current of (I)_L1Greater than the current flowing inductance L₂Current of (I)_L2，I_L1>I_L2(ii) a Due to the inductance L₁And L₂Belongs to two ends of the same induction coil, and the current I is seen from a point b_L1、I_L2In the opposite direction (I)_L1From point a to point c, I_L2Point c to point a), the current on the induction coil can be equivalent to I_L＝I_L1-I_L2Electric powerStream I_L1Will be in the inductance L₂Generating a mutual inductance current, the direction of the mutual inductance current and I_L2Opposite direction (mutual induction current direction from point a to point c), resulting in current I_L2Is smaller and smaller due to the inductance L₁And L₂And a capacitor C₁Forming a parallel resonance unit through which current flows₁Time-pair capacitor C₁Charging is performed, so that the potential at the point a rises, and the diode D₁Stopping, keeping the d point at high level, and making the d point potential be greater than the c point potential to make MOS tube Q₁Continuously keeping on; since the MOS tube Q₁The internal resistance is small when the MOS transistor is conducted, so that the MOS transistor Q is₁When the voltage between the drain and the source is small and the point c is approximately grounded, the diode D₂On, the potential at the e point is reduced, resulting in the MOS transistor Q₂The voltage between the grid and the source disappears, and the MOS tube Q₂Cutting off; over time, when the inductance L is₂When the mutual inductance current becomes zero, the capacitor C₁Completing charging;

then a capacitor C₁Starting discharge, seen from point b, through the inductor L₂Is greater than the inductance L₁Of the inductor L, thereby the inductance L₁A mutual inductive current is generated, the direction of the mutual inductive current is from a point c to a point a, the potential of the point c is increased, and the diode D₂Cut-off, e-point potential recovery, MOS transistor Q₂Gets a voltage between the grid and the source to be conducted, when the point a is approximately grounded, the diode D₁Conducting to reduce the potential at the point d, so that the MOS transistor Q₁The voltage between the grid and the source disappears and is cut off, and the MOS tube Q₂Continuously keeping on until the mutual inductance current reaches zero, representing the capacitance C₁Finishing the discharge;

and then repeating the above pair of capacitors C₁The induction coil generates continuous alternating current in the charging and discharging process; when the metal piece to be detected is close to the induction coil, eddy current is generated, and the metal piece to be detected can be heated. Inductor L₃As a choke inductor, the non-abrupt change characteristic of the inductive current is utilized to ensure that the MOS transistor is not damaged due to the flowing of huge current at the moment when the mutual inductive current is zero.

Known from skin effectWhen an alternating current passes through the conductor, the alternating current will flow from the surface of the conductor; will skin depthSubstitution into resonant frequencyTo obtainThe relationship between the skin depth and the variable capacitor is known; whereinDelta is the skin depth, mu is the magnetic conductivity of the metal piece to be detected, xi is the electric conductivity of the metal piece to be detected, L is the inductance value of the induction coil, and C is the capacitance of the variable capacitor connected into the circuit;

the inductance of the induction coil is determined by the coil itself and cannot be adjusted, so that the capacitor C is used for controlling the skin depth₁The variable capacitor is a capacitor with the capacitance adjustable within a certain range, and the capacitance is changed by changing the relative effective area between the stages or the distance between the stages, so that the aim of adjusting the frequency of the induced current is fulfilled.

Different metal pieces to be detected have different skin depths, so that the induction heater needs to obtain the surface thickness of the strain clamp and the quality standard of crimping according to different models according to the surface thickness of the metal piece to be detected, for example, the metal piece to be detected is a strain clamp when in use, the skin depth delta of the strain clamp is also known, and then the strain clamp is used according to the skin depthCalculating and adjusting the size of the variable capacitor, and adjusting the size of the capacitance of the access circuit to a required value through a capacitance size adjusting button on the variable capacitor; the larger the skin depth, the larger the capacitance C₁The larger the value of (A) is; the smaller the skin depth, the smaller the capacitance C₁The smaller the value of (a).

FIG. 2 is a graph of voltage waveforms at three points a, b and c during the operation of the circuit structure; as can be seen from the figure, the stable sine wave voltage is provided at the three points a, b and c, so that stable sine alternating current is generated on the induction coil, which shows that the output of the induction heater is more stable.

As can be seen from fig. 2, the waveform at point b is the absolute value of a sine wave; inductance L in steady state₁～L₃The voltage integral at both ends is zero and flows through a capacitor C₁The integral of the current is zero, and the voltage amplitude V of the point b can be calculated_bm(ii) a Let b point voltage V_b＝|V_bmX sin (t) l, t is voltage at point B equal to power supply B₁Voltage V of_ccThe time of (d); byTo obtainInductor L₃Voltage at both ends is V_b-V_ccTo the inductance L₃The voltage at two ends is integrated to obtainIs calculated to obtainDue to the inductance L₁、L₂The same, therefore, the voltage between the points a and c is twice the voltage at point b, i.e. 2V_bmI.e. the capacitance C₁Voltage V across_Lm＝2V_bmThe maximum peak current of the inductance of the induction coil

When inductance L₃When the inductance value of (2) is large, the current flows through the inductor L₃The current of (2) is basically direct current, and an inductor L₃Is used to compensate for the energy lost by the oscillation; due to the voltage amplitude V at point b_bmHas been calculated to beInductor L₃The AC peak current in an oscillation period is equal to the sum of the DC current and the AC peak current; to the inductance L₃The voltage integration is carried out at the two ends to obtain a current-passing inductor L₃Has a peak current value ofThus the inductance L₃Too small an inductance value of (a) may result in an inductance L₃The current peak of (a) is large, resulting in unnecessary loss, and thus the inductance L₃Selection and inductance L₁、L₂Of comparable size.

When the models of the MOS tube and the diode are selected, the breakdown current of the MOS tube and the diode is required to be ensured to be larger than the maximum peak current I of the inductor of the induction coil_m。

Nothing in this specification is said to apply to the prior art.