CN216672864U - Superaudio induction heating load matching system - Google Patents

Abstract

The utility model discloses a superaudio induction heating load matching system, which is characterized in that: the matching transformer T comprises a transformer T1 and a transformer T2, the secondary side of the transformer T1 is connected with the primary winding of the transformer T2 in series through the resonance capacitor C, the induction coil L and the equivalent resistor r are connected to the secondary side of the transformer T2, and the product of the turn ratio K1 of the transformer T1 and the turn ratio K2 of the transformer T2 is equal to the turn ratio of the matching transformer T. The utility model carries out matching through two stages of transformers, can reasonably distribute the turn ratio of the two transformers according to the parameters of the capacitor, reduces the voltage of the transformers and the voltage of the capacitor, and greatly improves the reliability of the system. The sum of the capacities of the two transformers is the same as the capacity of the original transformer, so that the cost difference is not large after the two transformers are changed into the two transformers.

Description

Superaudio induction heating load matching system

Technical Field

The utility model relates to a superaudio induction heating load matching system.

Background

In the series type ultrasonic frequency induction heating system, impedance matching is generally performed using a transformer, and a primary resonance and a secondary resonance are divided according to a mounting position of a resonance capacitor, and the primary resonance is performed when the resonance capacitor is mounted on a primary side of the transformer, and the secondary resonance is performed when the resonance capacitor is mounted on a secondary side of the transformer (as shown in fig. 1).

The primary resonance is that a resonance capacitor C is connected in series with a primary winding loop of a transformer, an induction coil L is connected with the secondary side of the transformer, r is an equivalent resistance, and the resonance frequency is as follows:

f is the resonance frequency (Hertz); l is equivalent inductance (henry); k is the ratio of the number of primary and secondary turns of the transformer; c is the resonance capacitance (farad).

The relationship between the voltages is: u2 ═ U1/K; u1 ═ U × Q;

u is the output voltage of the inverter power supply, and is generally 530V; u1 is the transformer primary voltage; u2 is the transformer secondary voltage; q is a quality factor. The voltage Uc across the resonant capacitor C is equal to U1 in magnitude and 180 ° out of phase. Voltage U across the induction coil L_LSame as U2.

The quality factor Q is related to the operating frequency, inductance, and equivalent resistance, and is typically 5-10 for superaudio systems.

Q＝ω*L/r

If the installation Q is 8, the transformer primary voltage U1-530 x 8-4240V is calculated, i.e. the voltage across the resonant capacitor C is 4240V. The high working voltage has high manufacturing difficulty for the transformer, and the resonance capacitor is easy to break down and damage and unsafe when the transformer is frequently subjected to turn-to-turn breakdown, primary and secondary breakdown, primary and iron core breakdown and the like in actual use.

The secondary resonance is formed by connecting a resonance capacitor C and an induction coil L in series and then connecting the resonance capacitor C and the induction coil L to the secondary side of the transformer. The resonant frequency is:

it can be seen that the resonant frequency of the secondary resonance is independent of the transformer turn ratio K.

The voltage relations are as follows: u2 ═ U1/K; u shape_L＝U2*Q；U_L＝U_C；

The voltage at the two ends of the induction coil L has the same amplitude as the voltage at the two ends of the resonance capacitor C, and the phase difference is 180 degrees, which is Q (quality factor) times of the secondary voltage of the transformer.

Taking a 50KW super-audio heating system as an example, the turn ratio of a transformer is about 10/1, the output voltage of an inverter power supply is calculated according to 530V, the Q value is 8, and U2 is 530/10 is 53; u shape_CThe voltage at 53 × Q is 53 × 8 — 424V, which is lower than the voltage at the primary resonance by a factor of K (transformer turns ratio). It can be seen that the withstand voltage of the primary voltage and the resonance capacitor of the transformer at the secondary resonance is much lower than that of the primary resonance, so that the manufacturing difficulty of the transformer is greatly reduced, and the sectional area of the iron core is greatly reduced due to the reduction of the voltage, so that the volume of the transformer is greatly reduced. The service life of the resonant capacitor is thus increased.

Secondary resonance has many advantages over primary resonance but is not used in some cases, such as when the inductance of the induction coil L is small. In many cases (such as shaft quenching, pipe bending, etc.), the induction coil has only 1 turn, the diameter is several centimeters to ten and several centimeters, the inductance is only dozens of nanohenries to several hundreds of nanohenries, and is less than 1 microhenries (uH), and the capacitance of the resonance capacitor is about 225uF according to the formula calculation according to the resonance frequency of 15KHz and the inductance of 0.5 uH. It can be seen from the specification of the capacitor manufacturer that at such high frequencies, there is no capacitor with such large capacity at all, typically only a few uF, and most 20 uF, for example, RFM0.65-1000-15S, the capacitance is only 6 × 4.18 ═ 25.08uF, and if multiple capacitors are used in parallel, 225/25.08 ≈ 9 are needed, and each capacitor has a size of 336 × 126 × 220mm and a weight of 14Kg, which is theoretically feasible, but is practically infeasible due to the excessively large volume and stray inductance, cost, etc.

In this case, only primary resonance can be used, the resonance capacitor is at the primary side of the transformer, the capacitance ratio is smaller than the square multiple of the turn ratio of the secondary side transformer, the turn ratio of the induction coil is only 1 turn, the equivalent resistance r is also very small, the turn ratio of the transformer is higher, taking 50KW as an example of direct 30mm round shaft quenching, the turn ratio is about 30, and the capacitance of the capacitor is 225/30 during primary resonance²The capacitance of RFM4.0-10-30S-0.24uF can be set to 0.25uF as viewed from the capacitance specification.

Disclosure of Invention

The technical problem to be solved by the utility model is as follows: the problem of too high voltage of a capacitor and a transformer in a series ultrasonic induction heating primary resonance system.

In order to solve the above problems, the technical solution of the present invention is to provide a superaudio induction heating load matching system, which is characterized in that: the matching transformer T comprises a transformer T1 and a transformer T2, the secondary side of the transformer T1 is connected with the primary winding of the transformer T2 in series through the resonance capacitor C, the induction coil L and the equivalent resistor r are connected to the secondary side of the transformer T2, and the product of the turn ratio K1 of the transformer T1 and the turn ratio K2 of the transformer T2 is equal to the turn ratio of the matching transformer T.

Preferably, the secondary voltage U of the transformer T1₂₁＝U₁₁/K1, wherein U₁₁Is the primary voltage of transformer T1, K1 is the turns ratio of transformer T1;

primary voltage U of the transformer T2₁₂＝U_C＝U₂₁Q, wherein U_CIs the voltage across the resonant capacitor C, U₂₁Is the secondary voltage of transformer T1, Q is the quality factor;

secondary voltage U of the transformer T2₂₂＝U_L＝U₁₂/K2, wherein U_LFor sensing the voltage across the coil L, U₁₂K2 is the turns ratio of transformer T2, which is the primary voltage of transformer T2.

Preferably, the resonant frequency of the resonant capacitor C is

Wherein L is the inductance of the induction coil, K2 is the turns ratio of the transformer T2, and C is the resonance capacitance.

Compared with the prior art, the utility model has the beneficial effects that:

the utility model carries out matching through two stages of transformers, can reasonably distribute the turn ratio of the two transformers according to the parameters of the capacitor, reduces the voltage of the transformers and the voltage of the capacitor, and greatly improves the reliability of the system. Because the sum of the capacities of the two transformers is the same as the capacity of the original transformer, the cost difference is not great after the two transformers are changed, and the problems that the capacitance of a series type superaudio induction heating primary resonance system and the voltage of the transformer are too high are solved under the condition that the cost is not increased.

Drawings

FIG. 1 is a schematic diagram of a superaudio induction heating primary resonant system and a secondary resonant system;

fig. 2 is a schematic diagram of a superaudio induction heating load matching system according to the present invention.

Detailed Description

In order to make the utility model more comprehensible, preferred embodiments accompanied with figures are described in detail below.

As shown in fig. 2, the ultrasonic frequency induction heating load matching system of the present invention adopts a two-stage transformer combination mode, and fully combines the advantages of primary resonance and secondary resonance, so that the problem is solved.

Dividing the matching transformer T into 2 transformers, T1 and T2, enabling the turn ratio K1K 2K of the 2 transformers T1 and T2, installing a resonant capacitor C between the two transformers, and enabling the resonant frequency to be:

where L is the inductance of the inductor, K2 is the turns ratio of transformer T2, and C is the resonant capacitance, it can be seen that the resonant frequency F is related only to the turns ratio K2 of transformer T2, and is not related to transformer T1.

The relationship between the voltages is: secondary voltage U of transformer T1₂₁＝U₁₁/K1, wherein U₁₁Is the primary voltage of transformer T1, K1 is the turns ratio of transformer T1;

primary voltage U of transformer T2₁₂＝U_C＝U₂₁Q, wherein U_CIs the voltage across the resonant capacitor C, U₂₁Is the secondary voltage of transformer T1, Q is the quality factor;

secondary voltage U of transformer T2₂₂＝U_L＝U₁₂/K2, wherein U_LFor sensing the voltage across the coil L, U₁₂K2 is the turns ratio of transformer T2, which is the primary voltage of transformer T2.

The inductance value is 0.5uH, the frequency is 15KHz, the Q value is 8, the power is 50Kw, and the turn ratio of the transformer is 30. When K1 is determined to be 6, K2 ═ K/3 ═ 30/6 ═ 5, the capacitance of the resonant capacitor C is calculated according to the formula to be about 9 uF. The voltage across the resonant capacitor C is:

U₂₁＝U₁₁/K1＝530/6≈88V；

U_C＝U₂₁*Q＝88*8＝704V；

the primary current of the transformer T1 is 50Kw/530V ≈ 94A, and the secondary current is 94 × 6 ≈ 564A. The secondary of the transformer T1 is connected in series with the resonant capacitor C and the primary winding of the transformer T2, and the currents are the same. According to the calculation result, a capacitor specification is searched, the rated voltage of the capacitor RFM0.75-500-15S is 750V, the current is 666A, the rated voltage is larger than the calculated current voltage value, the frequency is 15KHz, the capacitance is 4 x 2.36 to approximately equal to 9uF, and all the parameters meet the system requirement and can be used.

The matching is carried out through the two stages of transformers, the turn ratio of the two transformers can be reasonably distributed according to the parameters of the capacitor, the voltage of the transformers and the voltage of the capacitor are reduced, and the reliability of the system is greatly improved. The sum of the capacities of the two transformers is the same as the capacity of the original transformer, so that the cost difference is not large after the two transformers are changed into the two transformers.

Claims (3)

1. A superaudio induction heating load matching system which characterized in that: the matching transformer T comprises a transformer T1 and a transformer T2, the secondary side of the transformer T1 is connected with the primary winding of the transformer T2 in series through the resonance capacitor C, the induction coil L and the equivalent resistor r are connected to the secondary side of the transformer T2, and the product of the turn ratio K1 of the transformer T1 and the turn ratio K2 of the transformer T2 is equal to the turn ratio of the matching transformer T.

2. A superaudio induction heating load matching system as claimed in claim 1, wherein: secondary voltage U of the transformer T1₂₁＝U₁₁/K1, wherein U₁₁Is the primary voltage of transformer T1, K1 is the turns ratio of transformer T1;

primary voltage U of the transformer T2₁₂＝U_C＝U₂₁Q, wherein U_CIs the voltage across the resonant capacitor C, U₂₁Is the secondary voltage of transformer T1, Q is the quality factor;

secondary voltage U of the transformer T2₂₂＝U_L＝U₁₂/K2, wherein U_LFor sensing the voltage across the coil L, U₁₂K2 is the turns ratio of transformer T2, which is the primary voltage of transformer T2.

3. As claimed in claim 1The superaudio induction heating load matching system is characterized in that: the resonant frequency of the resonant capacitor C is

Wherein L is the inductance of the induction coil, K2 is the turns ratio of the transformer T2, and C is the resonance capacitance.

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