CN1161596A - Electric power conversion circuit by changing sine ac power to balance amplitude-modulated wave - Google Patents

Abstract

The electric energy transformer is suited for intermediate-frequency smelting, high-frequency heat treatment, electromagnetic stove and supersonic wave cleaning. The apparatus consists of a line filter, a double complete bridge resonant switching circuit conencted to the filter and a balanced modulating exciter which is connected to the circuit. The double complete resonant switching circuit gets an exciting voltage singnal from the exciter and produces a balanced AM wave. Advantages are: low cost, less components, high filtering and transforming efficiency.

Description

A kind of electric energy change-over circuit that sinusoidal ac is converted to Balance Amplitude Modulation Wave

The invention provides a kind of with sinusoidal ac directly be converted to height (in) circuit of Balance Amplitude Modulation Wave frequently.

At present, devices such as intermediate frequency smelting, high frequency heat processing, electromagnetic stove, ultrasonic waves for cleaning, although because of the difference of purposes and power capacity, particular circuit configurations and parameter also are not quite similar, functional-block diagram is on all four.Wherein most important non-linear conversion circuit has two: one, rectification circuit, and its effect is to change alternating current into unidirectional pulsating current; The 2nd, high (in) the band electronic switch, its effect be with the direct current that unidirectional pulsating current produces after filtering cut into height (in) frequently rectangular pulse or convert to height (in) frequency sine-wave (resonant switch circuit).Remaining circuit has filter circuit, and its effect is the AC ripple that absorbs in the pulsating direct current, and it is become approximately The smooth direct current of times supply voltage; Line filter, its effect are to reduce the pollution of the switch clutter of rectification and switching circuit to electrical network; Also have requisite protective circuit, its effect is to prevent that switching tube is because of overvoltage, overcurrent or overheated the damage.The shortcoming of this change-over circuit is: 1. the electric energy conversion times is many, and loss is also big.2. filter circuit increases equipment volume, and weight increases, and cost improves; 3. filter element increases surge current, and weight increases, and cost improves; 3. filter element increases surge current or the raising of resistance electromotive force, thereby causes the overcurrent of rectification and switch element or overvoltage to damage easily.4. the spectral range of the switch clutter of rectification and switch element is very wide, and the line filter weak effect still pollutes electrical network.

The purpose of this invention is to provide and a kind of sinusoidal ac is converted to the electric energy change-over circuit of Balance Amplitude Modulation Wave,, reduce manufacturing cost to improve conversion efficiency.

The present invention is achieved in that the bridge resonant switch circuit of enjoying a double blessing after this circuit has a line filter and is connected on line filter, and the Balance Amplitude Modulation Wave that it produces is added on the transducer; Also have a balance modulator driver, it is connected on the doube bridge resonant switch circuit, and it is sent the driving voltage signal.

This electric energy change-over circuit will exchange and directly be converted to Balance Amplitude Modulation Wave, so it has following advantage: 1. saved current rectifying and wave filtering circuit, thereby not only saved element, and reduced volume, alleviate weight, reduced cost, and reduced loss, improved efficient.2. owing to adopt the bridge resonant switch of enjoying a double blessing to carry out the electric energy conversion, the spectrum component of curtage in the circuit, have only carrier and modulating signal (50Hz sine wave) with frequently and difference frequency, both differ only 100Hz, thereby can eliminate reverse interference to electrical network with a resonance in the filter of carrier frequency.3. because the frequency band of Balance Amplitude Modulation Wave is narrow, the efficient of energy transducer is also higher.

Operation principle below in conjunction with description of drawings physical circuit of the present invention.

Fig. 1 is an electric functional-block diagram of the present invention.Fig. 2 is the circuit diagram of bridge resonant switch of enjoying a double blessing among the present invention.Fig. 3 is the electric functional-block diagram of a kind of circuit of balance modulator driver among the present invention.

As shown in drawings, a kind of electric energy change-over circuit that sinusoidal ac is converted to Balance Amplitude Modulation Wave of the present invention, the bridge resonant switch circuit (2) of enjoying a double blessing after having a line filter (1) and being connected on line filter (1), the Balance Amplitude Modulation Wave that it produces is added on the transducer (4); Also have a balanced amplitude modulation exciter (3), it is connected on the bridge resonant switch circuit (2) of enjoying a double blessing, and it is sent the driving voltage signal.

As shown in Figure 2, in the bridge resonant switch circuit of enjoying a double blessing, the capacitor C that is cascaded, inductance L two ends are connected on the E of eight insulated gate bipolar triode IGBT respectively ₁, E ₃, C ₂, C ₄The utmost point and E ₅, E ₇, C ₆, C ₈Extremely go up the C of eight insulated gate bipolar triodes ₁, C ₃, C ₅, C ₇The utmost point is connected together, E ₂, E ₄, E ₆, E ₈The utmost point is connected together.

Capacitor C, inductance L also can be connected in parallel.

As shown in Figure 3, in the balanced amplitude modulation exciter, connect voltage coupling excitation device (6) behind the balanced amplitude modulation modulator (5), voltage coupling excitation device respectively with the bridge resonant switch circuit of enjoying a double blessing in the G of eight insulated gate bipolar triode IGBT ₁, G ₆The utmost point, G ₂, G ₅The utmost point, G ₄, G ₇The utmost point, G ₃, G ₈Extremely continuous, high (in) frequently oscillator (7) be connected on the balanced amplitude modulation modulator (5).

As shown in Figure 2, inductance L and capacitor C are formed series resonant tank, and resonance frequency is approximately $f=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}$ 。8 insulated gate bipolar triode IGBT form the bridge network of enjoying a double blessing.IGBT wherein ₁, T ₂, T ₅, T ₆Form a bridge circuit, IGBT ₃, T ₄, T ₇, T ₈Form another bridge circuit.Be input as between positive half period IGBT at the 50Hz sinusoidal ac ₁, T ₆During conducting simultaneously, electrical network forms the positive half cycle waveform of minor cycle to the charging of LC loop; IGBT ₂, T ₅During conducting simultaneously, LC discharges by electrical network in the loop, thereby the negative half period waveform of formation minor cycle during this period, and another bridge circuit is not worked.When 50Hz was input as negative half period, first bridge circuit was not worked.IGBTE ₃, T ₈During conducting simultaneously, electrical network forms negative smaller part periodic waveform, IGBT to the charging of LC loop ₁, T ₇During conducting simultaneously, the discharge of LC loop forms positive smaller part periodic waveform.Certainly, because the loss in the LC resonant tank, the peak value that discharges and recharges two little half cycles is different big, but under the not too big situation of damping, in the half period, is example with positive half cycle at 50Hz, and in 30 ℃～150 ℃ scopes, positive and negative little half cycle is symmetry substantially.Only in 0 ℃～30 ℃ and 150 ℃～180 ℃ scopes, positive and negative little half cycle has than obvious errors.Therefore, can be similar to and think, the bridge resonant switch of enjoying a double blessing produces and is added on the energy transducer is to make modulation signal with the 50Hz simple alternating current, makes the Balance Amplitude Modulation Wave of carrier wave with high frequency (or intermediate frequency) oscillator signal.

Because the series resonant circuit impedance is very little, and any moment always have two pipes to work simultaneously, be half of power supply crest voltage so be added in crest voltage on each pipe.And the maximum current of each pipe of flowing through is promptly when crest voltage is imported, the peak current during maximum power output, and also output current is controlled by grid voltage.In the one-period of input power supply, any pipe has half period not work, and the half the time that does the work by snatches in the half period in addition.Therefore, the maximum current when by crest voltage has been selected after the power capacity of pipe, promptly needn't worry the g-load problem of pipe.Thereby also just need not to add overvoltage, overcurrent and overtemperature protection.But this is absolutely necessary in general transducing circuit.Certainly, if be added with protective circuit,, just can improve the power output and the power density of equipment significantly to give full play to the limit utilization potentiality of switching tube.

The transducer (4) that the present invention is alleged is inductance coil L and material-to-be-heated in intermediate frequency smelting, high frequency heat treatment facility and electromagnetic stove, is supersonic generator in ultrasonic cleaning apparatus.

The orderly work of the bridge resonant switch of enjoying a double blessing of the present invention is to control by the driving voltage that the balance modulator driver produces.Carrier wave by high (in) frequently oscillator (7) produce, modulation signal is the sampled signal of 50Hz power supply.The driving voltage that these two kinds of signals produce is connected on the grid of the insulated gate bipolar triode IGBT in the bridge resonant switch circuit of enjoying a double blessing, controls its break-make.

Be connected to detecting element L in the lc circuit in the bridge resonant switch of enjoying a double blessing ₁, and be connected to height (in) frequently in the oscillator, synchronous with the vibration that guarantees two circuit.Detection signal is made the reference signal of protection automatically and power control simultaneously again.

Claims (3)

1. electric energy change-over circuit that sinusoidal ac is converted to Balance Amplitude Modulation Wave, this circuit has a line filter (1), it is characterized in that, described electric energy change-over circuit also has a bridge resonant switch circuit (2) of enjoying a double blessing after being connected on line filter, and the Balance Amplitude Modulation Wave that its produces is added on the transducer (4); A balance modulator driver (3), it is connected on the bridge resonant switch circuit (2) of enjoying a double blessing, and it is sent the driving voltage signal.

2. a kind of electric energy change-over circuit that sinusoidal ac is converted to Balance Amplitude Modulation Wave as claimed in claim 1, on the described bridge resonant switch circuit (2) of enjoying a double blessing, the capacitor C that is cascaded, inductance L two ends are connected on the E of eight insulated gate bipolar triode IGBT respectively ₁, E ₃, C ₂, C ₄The utmost point and E ₅, E ₇, C ₆, C ₈Extremely go up the C of eight insulated gate bipolar triodes ₁, C ₃, C ₅, C ₇The utmost point is connected together, E ₂, E ₄, E ₆, E ₈The utmost point is connected together.

3. as claimed in claim 2ly a kind of sinusoidal ac is converted to the electric energy change-over circuit of Balance Amplitude Modulation Wave, it is characterized in that described capacitor C, inductance L also can be connected in parallel.

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