CN103944411A

CN103944411A - Generator frequency converter

Info

Publication number: CN103944411A
Application number: CN201410142389.3A
Authority: CN
Inventors: 龚治俊
Original assignee: CHONGQING YUXIN PINGRUI ELECTRONIC Co Ltd
Current assignee: CHONGQING YUXIN PINGRUI ELECTRONIC Co Ltd
Priority date: 2014-04-10
Filing date: 2014-04-10
Publication date: 2014-07-23

Abstract

The invention discloses a generator frequency converter which comprises an LC low pass filter. The generator frequency converter is characterized in that the input end of the LC low pass filter is connected with a low-frequency full-bridge reversing circuit, the input end of the low-frequency full-bridge reversing circuit is respectively connected with a PWM chopping modulation circuit and a diode, and the PWM chopping modulation circuit is a switch transistor. The generator frequency converter is low in cost, circuit losses are reduced, the heating phenomenon is reduced, and circuit reliability is increased.

Description

Electric generator frequency-converter

Technical field

the present invention relates to the frequency converter that a kind of generator is used.

Background technology

General frequency conversion digital electricity generating, this generator is an explosive motor, a magneto, frequency converter and generator casing and other auxiliary elements composition. this digital electricity generating is the substitute products of traditional excitation generator, there is power supply quality high, the advantages such as volume is little lightweight, and efficiency is high, and noise is low.Wherein the price of frequency converter is higher, has directly caused the price of whole generator higher.In Fig. 1, show the AC-DC-AC topology of prior art Plays, in existing standard circuit, there is capacitor C 2 ' filtering, the voltage at C2 ' two ends is direct voltage completely, simultaneously the insulation coral bipolar transistor S1 ' in available circuit to the coral bipolar transistor S4 ' that insulate be not the effect of polarity switch, modulate but play PWM.That is to say, the coral bipolar transistor S1 ' that insulate in available circuit is operated under the on off state of upper frequency to the coral bipolar transistor S4 ' that insulate, and its loss is very high.

Summary of the invention

The object of this invention is to provide the electric generator frequency-converter that a kind of cost is low, the life-span is long.

To achieve these goals, by the following technical solutions: a kind of electric generator frequency-converter, comprise LC low pass filter, it is characterized in that: the input of described LC low pass filter is connected with low frequency full bridge commutating circuit, the input of low frequency full bridge commutating circuit is connected with respectively PWM chopping modulation circuit and diode, and wherein PWM chopping modulation circuit is switching transistor.

Low frequency full bridge commutating circuit is two branch road compositions in parallel, is in series with two switching transistors on every branch road.

Described switching transistor is insulation coral bipolar transistor, mos field effect transistor, high-power insulation coral bipolar transistor or integrated gate commutated thyristor, or other has the element of on-off action.

Tool of the present invention has the following advantages:

(1) reduce circuit loss, reduce heating.The present invention has replaced three silicon controlled rectifiers in three-phase bridge rectification circuit with the switch element Q1 ~ Q3 of 3 higher operational frequency, its conduction loss and original quite, in fact the switching loss increasing is equivalent to a small half of to the master switch loss of S4 ' of S1 ' in former background circuit, and S1 to S4 in the present invention is operated in low-frequency polarity switching state, its switching loss almost can be ignored, so conduction loss in fact of the present invention is suitable with background technology, and more than switching loss subtracts and be a half even.

(2) reduced design cost.Insulation coral bipolar transistor S1 ~ S4 in the present invention only needs low frequency switch element, low frequency switch element is than HF switch element considerably cheaper, and the switching loss during due to its work is very little, only there is heating in the situation of conduction loss to want much less, so can use the element of lower rated current can meet instructions for use.The technical parameter of coral bipolar transistor Q1 ~ Q3 of insulating in the present invention require with prior art in insulation coral bipolar transistor S1 ' ~ S4 ' of using suitable, but average current only for prior art use S1 ~ S4 average current 1/3rd, adding the coral bipolar transistor S1 ~ S4 that insulate in the present invention only needs low frequency switch and rated current to reduce, so resulting cost is reduced.

(3) in the present invention, also cancel electrochemical capacitor C2 ', both reduced costs, reduced loss, reliability and the life-span of also having improved product.Electrochemical capacitor life is short, and under the electric current of upper frequency, obviously, loss is larger in heating.In the prior art, the cost of electrochemical capacitor C2 ' is very high, and particularly in powerful digital electricity generating frequency converter, this electric capacity is not only expensive but also reduced the reliability of product.

Brief description of the drawings

Fig. 1 is the circuit theory diagrams of prior art;

Fig. 2 is the physical circuit figure of prior art;

Fig. 3 is the circuit theory diagrams of the embodiment of the present invention 1;

Fig. 4 is the physical circuit figure of the embodiment of the present invention 1;

Fig. 5 is the oscillogram that in Fig. 4, A is ordered;

Fig. 6 is the oscillogram that in Fig. 4, B1 is ordered;

Fig. 7 is the oscillogram that in Fig. 4, B2 is ordered;

Fig. 8 is the oscillogram of Fig. 4 output;

Fig. 9 is the control signal figure of coral bipolar transistor Q1, insulation coral bipolar transistor Q2, insulation coral bipolar transistor Q3, insulation coral bipolar transistor S1, insulation coral bipolar transistor S2, insulation coral bipolar transistor S3 and insulation coral bipolar transistor S4 of insulating in Fig. 4;

Figure 10 is the electrical schematic diagram of the concrete application of the present invention;

Figure 11 is the electrical schematic diagram of embodiment 3;

Figure 12 is the physical circuit figure of embodiment 3.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention will be further described.

As shown in Figure 3 and Figure 4, a kind of electric generator frequency-converter, comprise LC low pass filter, the input of described LC low pass filter is connected with low frequency full bridge commutating circuit, the input of low frequency full bridge commutating circuit is connected with respectively PWM chopping modulation circuit and diode, and wherein PWM chopping modulation circuit is insulation coral bipolar transistor.Low frequency full bridge commutating circuit is two branch road compositions in parallel, is in series with two insulation coral bipolar transistors on every branch road.

Introduce the operation principle of following this circuit below:

The three-phase output of A, motor is connected respectively to the negative electrode of diode D1 to diode D3, diode D1 connects respectively the collector electrode of insulation coral bipolar transistor Q1 to Q3 to the negative electrode of diode D3, the emitter of insulation coral bipolar transistor Q1 to Q3 is connected to low frequency full bridge commutating circuit, and in low frequency full bridge commutating circuit, the oscillogram at A place as shown in Figure 5.

B, do after polarity is switched and obtain B1 and B2 to the coral bipolar transistor S4 that insulate through insulation coral bipolar transistor S1 again, see shown in Fig. 6 and Fig. 7;

C, after crossing LC filtering, obtain Uout, see Fig. 8, Uout waveform is exactly output voltage waveforms of the present invention.

The control signal of insulation coral bipolar transistor Q1 is Vq1, the control signal of insulation coral bipolar transistor Q2 is Vq2, the control signal of insulation coral bipolar transistor Q3 is Vq3, and the control signal of insulation coral bipolar transistor S1 to S4 is respectively corresponding Vs1 to Vs4.Wherein Vq1 ~ Vq3 is PWM modulation signal, and frequency more than 10K, has reduced doubly a lot conventionally in Figure 10 in order to show.Vs1 ~ Vs4 is positive-negative polarity switching signal, and frequency is generally 50HZ or 60HZ, consistent with output frequency.

Vs1 ~ Vs4 signal is changeless, all inserted Dead Time and avoided switch element to occur leading directly to, and Vq1 ~ Vq3 signal regulates according to output voltage and electric current at edge, and Vq1 ~ Vq3 signal can use identical control signal.And insulation coral bipolar transistor S1 ~ S4 of the prior art usually needs to use the 4 road pwm control signals of controlling with dead band.Than the present invention, in upper frequency switching signal, insert Dead Time much bigger to the performance impact of product, because the ratio of Dead Time and maximum pulse is larger, reach tens of/mono-.And the present invention is because Dead Time is inserted in low frequency polarity switching signal, the ratio of Dead Time and switching signal pulse duration can reach tens thousand of/mono-, affects very little.

Insulation coral bipolar transistor S1 ' in available circuit to the coral bipolar transistor S4 ' that insulate be not the effect of polarity switch, but play PWM modulation, that is to say, in available circuit, S1 ' is operated in to S4 ' under the on off state of upper frequency, the S1 ~ S4 in the present invention of its loss ratio be only operated in low frequency polarity switch under much higher.

As shown in figure 10, petrol engine or Diesel engine drive permanent magnet generator to rotate, and the output three-phase high-voltage power supply of permanent magnet generator and low-tension supply are connected to the input of frequency converter.Its high voltage source is that hundreds of volts and hundreds of hertz are indefinite, and low-tension supply is tens of volts and hundreds of hertz.High voltage source obtains the sinusoidal envelope voltage of full-wave rectification after PWM chopping modulation circuit, and it is with PWM modulation product, and only has positive polarity.After low frequency full bridge commutating circuit, obtain existing positive polarity and also having the sinusoidal envelope voltage of negative polarity, obtaining low-frequency power output finally by LC low pass filter.Whole circuit is coordinated and is controlled by MCU control unit (MicroControllerUnit), it is responsible for generating suitable pwm signal according to the voltage and current size of output sampling, remove to drive PWM chopping modulation device by IGBT isolated drive circuit, export suitable commutation signal simultaneously and remove to control low frequency full bridge commutating circuit through IGBT drive circuit, make output obtain sinusoidal wave positive-negative polarity.

Simultaneously low-tension supply voltage stabilizing circuit provides the low-voltage supply needing for MCU control unit and other circuit, in the product that need to adjust engine speed, also have tacho-pulse shaping circuit to provide tacho-pulse for MCU control unit, and in MCU, generate step motor control pulse, go to drive throttle stepping motor to rotate by stepper motor driving circuit, and then change the rotating speed of engine.

Embodiment 2: as different from Example 1, insulation coral bipolar transistor is used MOSFET(mos field effect transistor instead) replace.

Embodiment 3: the schematic diagram of the frequency converter that the output as shown in Figure 11 and Figure 12 is dual output and physical circuit figure, its essence is the series connection of univoltage output, its control section is just the same.

Claims

1. an electric generator frequency-converter, comprise LC low pass filter, it is characterized in that: the input of described LC low pass filter is connected with low frequency full bridge commutating circuit, the input of low frequency full bridge commutating circuit is connected with respectively PWM chopping modulation circuit and diode, and wherein PWM chopping modulation circuit is switching transistor.

2. electric generator frequency-converter as claimed in claim 1, is characterized in that: low frequency full bridge commutating circuit is two branch road compositions in parallel, is in series with two switching transistors on every branch road.

3. electric generator frequency-converter as claimed in claim 1 or 2, is characterized in that: described switching transistor is insulation coral bipolar transistor, mos field effect transistor, high-power insulation coral bipolar transistor or integrated gate commutated thyristor.