A high-power symmetrical CLC high-frequency resonant inverter

Abstract

The present invention discloses a high-power symmetrical CLC high-frequency resonant inverter power supply, including current-type inverters on the left and right sides and a symmetrical CLC high-frequency resonant cavity, wherein the symmetrical CLC high-frequency resonant cavity includes two groups of coils and two resonant capacitors C, which are symmetrically connected in a "mouth" shape. The high-frequency current sources on both sides of the symmetrical CLC high-frequency resonant cavity have the same power supply frequency and amplitude, and the phase angle differs from each other. The loads of the current-type inverters on both sides of the present invention are capacitive, realizing zero-current switching; this structure realizes the reuse of the resonant capacitor C, reduces the cost and volume of the power supply system, and eliminates the design and manufacturing difficulties of high-power high-frequency transformers. The working principle of the symmetrical CLC high-frequency resonant cavity of the present invention is like two high-frequency current sources acting on the same resonant cavity at the same time, realizing the integration of two CLC high-frequency resonant inverter power supplies, and the output power of the load coil is increased by 1 times. The two groups of high-frequency current sources can operate independently and serve as backup for each other.

Description

Technical Field

[0001] The invention relates to a large-capacity high-frequency resonant inverter, in particular to a high-power symmetrical CLC high-frequency resonant inverter power supply. Background Art

[0002] Large-capacity high-frequency resonant inverter refers to a large inverter with a capacity of several hundred kilowatts to thousands of kilowatts, a frequency of several hundred thousand hertz to several megahertz, and a switching frequency equal to the load resonant frequency. Large-capacity high-frequency resonant inverter power supply has a wide range of application prospects, such as quenching, heat penetration, melting, welding of metal heat treatment, high-frequency welding of steel sections and large-diameter steel pipes in heat sleeves, online annealing of steel bars, large-diameter steel, and stainless steel pipes, full-line automatic control power supply for reversible and continuous cold rolling mills, and solid-state high-frequency welding of precision steel pipes, etc., industrial electric vacuum device degassing heating, semiconductor material refining, plastic heat sealing, baking and purification, and some special applications such as optical fiber crystal pulling and gem refining, etc., which can meet the requirements of most industrial heat treatments and have a great role in promoting the development of the national economy.

[0003] High-frequency induction heating power supply is a typical application of large-capacity high-frequency resonant inverter. Compared with gas combustion heating or electric heating, induction heating has the advantages of energy saving, non-contact, fast speed, high efficiency, simple process, good product quality, improved production environment, and suitable for automated production lines. Therefore, it has been widely used and developed. At present, the research on high-frequency induction heating power supply has received increasing attention, but the domestic research on high-frequency induction heating power supply started late, the technology is relatively backward, and thyristor circuit structure is mostly used. Thyristor power supply requires industrial frequency step-up transformer, low power efficiency, short service life, and needs to be preheated before use. With the development of power electronics technology, the successful development of solid-state high-frequency devices power MOSFET, SIT, IGBT, the application of soft switching technology, and the high-frequency switching circuit developed has the advantages of small switching loss and conduction loss, easy startup, and high efficiency, making the development conditions of large-capacity high-frequency induction heating power supply system mature. It is a very realistic topic to replace thyristors with power semiconductor devices to achieve equipment upgrading.

[0004] like Figure 1 As shown in the figure, it is a typical high-power resonant inverter structure. Resonant inverters generally adopt a full-bridge structure and are divided into voltage-type resonant inverters and current-type resonant inverters. Figure 1 As shown in (a), the DC side of the voltage source resonant inverter topology is a voltage source, the output voltage is a square wave, and the subsequent load is generally a series resonant structure. Figure 1As shown in (b), the DC side of the current-type resonant inverter topology is a current source, the output current is a square wave, and the subsequent load is generally a parallel resonant structure. The current-type resonant inverter has low requirements on the withstand voltage and current level of the power device, does not require short-circuit protection, and the load matching is relatively simple, which reduces the requirements for the power device, makes the circuit operation more stable, and has high practical value. The advantages of the traditional current-type resonant inverter when operating in a small capacitive working state are as follows: when the power device is turned off, the series diode withstands the reverse voltage, so that the device is turned off at zero voltage; at the same time, in this working state, the current of the load coil branch increases, which is conducive to the output of active power. However, its disadvantage is the reverse recovery spike current generated during the reverse recovery process of the diode. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the object of the present invention is to provide a high-power symmetrical CLC high-frequency resonant inverter power supply.

[0006] To achieve the purpose of the present invention, the technical solution adopted by the present invention is:

[0007] A high-power symmetrical CLC high-frequency resonant inverter power supply includes a current-type inverter and a symmetrical CLC high-frequency resonant cavity on the left and right sides, wherein the symmetrical CLC high-frequency resonant cavity includes two groups of coils and two resonant capacitors C, which are symmetrically connected in a "mouth" shape; the two sides of the "mouth" shape are symmetrical resonant capacitors C, and the upper and lower branches of the symmetrical CLC high-frequency resonant cavity are each a group of coils.

[0008] Furthermore, the left side of the symmetrical CLC high-frequency resonant cavity is connected to the high-frequency current source output by the left current-type inverter, and the right side is connected to the high-frequency current source output by the right current-type inverter.

[0009] Furthermore, the high-frequency current sources on both sides of the symmetrical CLC high-frequency resonant cavity have the same power supply frequency and amplitude, and a phase angle difference of л.

[0010] Furthermore, the high-frequency current sources on both sides operate independently and serve as backup for each other.

[0011] Furthermore, the symmetrical CLC high frequency resonant cavity has two fixed resonant frequency points Where L is the equivalent inductance of the coil.

[0012] Furthermore, when 0<ω<ω1, the circuit is capacitive; when ω1<ω<ω2, the circuit is inductive; when ω>ω2, the circuit is capacitive.

[0013] Furthermore, the operating frequencies of the current-source inverters on the left and right sides are set to ω>ω2, and the loads of the current-source inverters on the two sides are capacitive, thereby realizing zero-current switching.

[0014] Furthermore, the symmetrical CLC high-frequency resonant cavity is a combination of two CLC high-frequency resonant inverter power supplies, which is equivalent to two high-frequency current sources acting on the same resonant cavity at the same time, and the output power of the load coil is increased by 1 times.

[0015] The beneficial effect of the present invention is that, compared with the prior art, the present invention designs a symmetrical CLC high-frequency resonant cavity structure, and the loads of the current-type inverters on both sides are capacitive, thereby realizing zero-current switching; this structure realizes the reuse of the resonant capacitor C, reduces the cost and volume of the power supply system, eliminates the design and manufacturing difficulties of a high-power high-frequency transformer, and can greatly reduce the volume and cost of the system.

[0016] The working principle of the symmetrical CLC high-frequency resonant cavity of the present invention is like two high-frequency current sources acting on the same resonant cavity at the same time, realizing the integration of two CLC high-frequency resonant inverter power supplies, and the output power of the load coil is increased by 1 times. The two sets of high-frequency current sources can operate independently and serve as backup for each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a typical high-power resonant inverter structure, a is a voltage-type resonant inverter topology, and b is a current-type resonant inverter topology;

[0018] Figure 2 It is the high-power symmetrical CLC high-frequency resonant inverter power supply structure described in the present invention;

[0019] Figure 3 This is the working principle of a single CLC high frequency resonant inverter;

[0020] Figure 4 It is the simulation result of high-power symmetrical CLC high-frequency resonant inverter power supply. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of this application.

[0022] like Figure 2 As shown, the high-power symmetrical CLC high-frequency resonant inverter power supply of the present invention adopts a left-right symmetrical form, and is composed of a current-type inverter on the left and right sides and a symmetrical CLC high-frequency resonant cavity, so as to achieve high-power high-frequency output. The left side of the symmetrical CLC high-frequency resonant cavity is connected to the output of the left current-type inverter, and the right side is connected to the output of the right current-type inverter.

[0023] The symmetrical CLC high-frequency resonant cavity includes two sets of coils (L, R) and two resonant capacitors C, which are symmetrically connected in a "mouth" shape; the two sides of the "mouth" are symmetrical resonant capacitors C, and the upper and lower branches of the symmetrical CLC high-frequency resonant cavity are a set of coils (L, R). The two high-frequency current sources on both sides of the symmetrical CLC high-frequency resonant cavity have the same power supply frequency and amplitude, but the phase angle differs from each other. The high-frequency current source on one side is equivalent to I m sin(ωt), then the high-frequency current source on the other side is equivalent to I m sin(ωt+π).

[0024] The working principle of the symmetrical CLC high-frequency resonant cavity is like two high-frequency current sources acting on the same resonant cavity at the same time, realizing the integration of two CLC high-frequency resonant inverter power supplies. The output power of the load coil is increased by 1 times, and the two sets of high-frequency current sources can operate independently and serve as backup for each other.

[0025] like Figure 3 As shown, the working principle of a single CLC high-frequency resonant inverter power supply: the input voltage U of the load tank circuit d is a sine wave, the input current I d is a rectangular wave. L, R are the equivalent inductance and resistance of the coil, and two capacitors C.

[0026] The total load impedance is:

[0027]

[0028] When the load resonates, there are two resonance points:

[0029]

[0030] And ω1<ω2. Assuming the operating frequency of the power device in the inverter is ω, the relationship between the impedance and ω is:

[0031]

[0032] It can be seen that when 0<ω<ω1, the circuit is capacitive; when ω1<ω<ω2, the circuit is inductive; when ω>ω2, the circuit becomes capacitive again.

[0033] Therefore, the symmetrical CLC high frequency resonant cavity has two fixed resonant frequency points: The operating frequency of the current-source inverters on the left and right sides is ω>ω2, making the loads of the current-source inverters on both sides capacitive, realizing zero-current switching. This structure realizes the reuse of the resonant capacitor C, reduces the cost and volume of the power supply system, eliminates the transformer, and solves the design and manufacturing problems of high-power high-frequency transformers.

[0034] At the resonance point ω1, it is equivalent to the series resonance of the right branch circuit, the impedance is minimum, the total impedance is minimum, the current output by the inverter is maximum, that is, the current flowing through the power device is also maximum. At this time, C in the right branch circuit does not play any role: it can neither achieve the purpose of load matching nor power regulation. At the resonance point ω2, it enters the comprehensive parallel resonance state, at which time the total impedance is maximum, that is, the current flowing through the power device of the main circuit is minimum, thereby reducing the requirements for power device selection. Therefore, when applying, the circuit is selected to work in the comprehensive parallel resonance state, and the active power output at this time is:

[0035]

[0036]

[0037] When the circuit works in the comprehensive parallel resonance state, when the capacitance value of C increases proportionally, the comprehensive parallel resonance frequency ω2 decreases, Q decreases, and the load active power increases; in this way, the parameters of the capacitor C can be changed to achieve different power outputs.

[0038] like Figure 4 The figure shows the simulation results of a high-power symmetrical CLC high-frequency resonant inverter. A simulation platform was built, the resonant frequency of the CLC resonant cavity was ω2 = 100kHz; the amplitude of the two current sources was 400A, the operating frequency was 103kHz, and the phase difference was 180 degrees.

[0039] The simulation results are as follows: Figure 4 The top row is the waveform of two current sources, with the same frequency and amplitude, and a phase difference of 180 degrees; the middle is the current waveform of the two load coils, with a frequency of 103kHz and a current amplitude of 1400A; the bottom is the voltage waveform of the two resonant capacitors C, with a voltage amplitude of less than 500V; at this time, the equivalent resistance of the two load coils is 0.2 ohms, and the total load power is about 200kW. It can be seen that through the reasonable design of the resonant cavity, the high-power high-frequency transformer can be omitted, and efficient matching of the load coil and high-power power supply can be achieved.

[0040] The beneficial effect of the present invention is that, compared with the prior art, the present invention designs a symmetrical CLC high-frequency resonant cavity structure, and the loads of the current-type inverters on both sides are capacitive, thereby realizing zero-current switching; this structure realizes the reuse of the resonant capacitor C, reduces the cost and volume of the power supply system, eliminates the design and manufacturing difficulties of a high-power high-frequency transformer, and can greatly reduce the volume and cost of the system.

[0041] The working principle of the symmetrical CLC high-frequency resonant cavity of the present invention is like two high-frequency current sources acting on the same resonant cavity at the same time, realizing the integration of two CLC high-frequency resonant inverter power supplies, and the output power of the load coil is increased by 1 times. The two sets of high-frequency current sources can operate independently and serve as backup for each other.

[0042] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation schemes of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, but not to limit the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A high-power symmetrical CLC high-frequency resonant inverter power supply, characterized in that: It includes a current-type inverter on the left and right sides and a symmetrical CLC high-frequency resonant cavity, wherein the symmetrical CLC high-frequency resonant cavity includes two groups of coils and two resonant capacitors C, which are symmetrically connected in a "mouth" shape; the two sides of the "mouth" shape are symmetrical resonant capacitors C, and the upper and lower branches of the symmetrical CLC high-frequency resonant cavity are respectively a group of coils; The symmetrical CLC high frequency resonant cavity has two fixed resonant frequency points Where, L is the equivalent inductance of the coil; The operating frequency of the current-type inverters on the left and right sides is made ω>ω2, and the loads of the current-type inverters on both sides are capacitive, thereby realizing zero-current switching.

2. The high-power symmetrical CLC high-frequency resonant inverter power supply according to claim 1 is characterized in that: The left side of the symmetrical CLC high-frequency resonant cavity is connected to the high-frequency current source output by the left current-type inverter, and the right side is connected to the high-frequency current source output by the right current-type inverter.

3. The high-power symmetrical CLC high-frequency resonant inverter power supply according to claim 2 is characterized in that: The high-frequency current sources on both sides of the symmetrical CLC high-frequency resonant cavity have the same power supply frequency and amplitude, and a phase angle difference of л.

4. The high-power symmetrical CLC high-frequency resonant inverter power supply according to claim 2 is characterized in that: The high-frequency current sources on both sides operate independently and serve as backup for each other.

5. The high-power symmetrical CLC high-frequency resonant inverter power supply according to claim 1 is characterized in that: When 0<ω<ω1, the circuit is capacitive; when ω1<ω<ω2, the circuit is inductive; when ω>ω2, the circuit is capacitive.

6. The high-power symmetrical CLC high-frequency resonant inverter power supply according to claim 1 is characterized in that: The symmetrical CLC high-frequency resonant cavity is a combination of two CLC high-frequency resonant inverter power supplies, which is equivalent to two high-frequency current sources acting on the same resonant cavity at the same time, and the output power of the load coil is increased by 1 times.

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