CN1048595C - Permanent-magnet brush-free DC generator with electronic voltage stabilizer - Google Patents

Abstract

The present invention relates to a permanent-magnet brush-free DC generator with electronic voltage stabilization. A main circuit of an electronic voltage stabilizer adopts a novel simplified PWM voltage increase type rectification or resonant switch voltage increase rectification, and has the operation mode that when the rotary speed of a generator is equal to the maximal rotary speed or is higher than the maximal rotary speed, a converter works in the state of diode rectification. When the rotary speed is lower than the maximum rotary speed, DC output is lifted to a voltage value corresponding to the diode rectification. Consequently, the stabilization of output direct current voltage is maintained. The present invention is suitable for the characteristic that the rotary speed of the generator varies in the course of operation of an airplane, a warship, a tank, a ship, an automobile, etc. The main circuit has the advantages of simplicity, high reliability and low cost.

Description

Permanent-magnet brush-free DC generator with electronic voltage stabilizer

Permanent-magnet brush-free DC generator with electronic voltage stabilizer belongs to DC generator.

Its generators such as present generation aircraft, automobile, steamer, warship, tank are by the engine transmission, and the rotating speed of generator is identical with the rotating speed of engine, or proportional, and changes with operating state.If the employing magneto only will make the output voltage excursion too big with diode rectification, the quota of pipe requires high, the reliability variation, and can not realize the electronic work of generator.If adopt controlled speed miscarriage to give birth to direct current, though output voltage is steady, main circuit and control circuit are all complicated, the cost height.

It is steady that task of the present invention provides a kind of output dc voltage, the reliability height, and circuit is simple, the DC permanent-magnetic brushless generator that cost is low.

Technical scheme of the present invention is made up of permanent magnet generator, synchronizing signal buffer circuit, analog switching circuit, current detection circuit, reference voltage circuit, voltage detecting circuit, voltage regulator circuit, current regulating circuit, logic gating circuit, isolated drive circuit, electronic voltage regulator main circuit and output filter circuit.Wherein current regulating circuit is again by clock generator, and hysteresis comparator, low pass filter, phase discriminator are formed.This characteristic feature of an invention is that the three-phase of permanent-magnet brushless generator output or single-phase alternating current are transformed into the direct current that burning voltage is exported with electronic circuit.For monophase machine, the electronic voltage regulator main circuit is made up of 4 diodes and 2 power transistors (double pole triode or power field effect pipe); For three phase electric machine, the electronic voltage regulator main circuit is made of 6 diodes and 3 power transistors, and diode is connected into single-phase or three-phase commutation bridge, and power transistor is connected to respectively on the diode of rectifier bridge minus side.Its working method is, when generator speed equaled maximum (top) speed, power transistor in parallel was in off state, and electronic voltage regulator is fully operational in the diode rectification state, makes the direct current of bridge rectifier output rated voltage.When the rotating speed of generator was lower than maximum (top) speed, the boost transistor work of 2～3 parallel connections was brought up to load voltage value with VD, thereby had kept the constant of output dc voltage.The characteristics that so just adapted to engine speed change in running such as aircraft, warship, steamer, tank, automobile.For example aircraft, most of the time are to cruise, and its engine speed is 90% of a maximum speed, and when aircraft downslide or ground idle running, its rotating speed is lower, is 50% of maximum speed when minimum.Therefore the maximum speed of generator speed excursion is about 2: 1 with the ratio of minimum speed.And the most of the time be to be operated under 90% the rotating speed of maximum speed, have only its rotating speed of less time to be lower than 90% of maximum speed.Warship, tank, automobile, steamer etc. are also similar.

This novel permanent magnetic brushless DC generator, not only circuit is simple, output voltage is steady, the excursion of VD greatly reduces, the operational environment of power consumption equipment also improves, meanwhile, because the power transistor wheel changes jobs, control circuit is greatly simplified, and the reliability of system is improved.In addition the operating time of power transistor very short, compare with the fast stream of full control, reliability and efficient all are improved.

For clearer, more completely set forth technical scheme of the present invention and operation principle, existing is that embodiment is described further with the three phase electric machine.

Accompanying drawing 1. permanent-magnet brush-free DC generator with electronic voltage stabilizer system block diagrams.

Accompanying drawing 2. electronic voltage regulator main circuit diagrams.

Accompanying drawing 3. synchronization signal detection circuits.

Accompanying drawing 4. current detection circuits.

Accompanying drawing 5. isolated drive circuits.

Accompanying drawing 6. voltage regulator circuits.

Accompanying drawing 7. hysteresis comparator circuits.

Accompanying drawing 8. clock generator circuits, the logic diagram of phase discriminator and low-pass filter circuit.

Synchronizing signal isolation detection circuit (1) obtains six natural commutation point by the isolation detection to this phase input voltage among the figure, generates the square wave synchronizing signal.Three analog switches (2) of synchronizing signal control are sent into hysteresis comparator (7) to the current feedback signal timesharing of three-phase current detection.Error signal (the U of outer voltage _r---U _f) obtain the given I of electric current through voltage regulator (5) amplification _rSignal, this signal and current feedback signal I _fProduced the PWM ripple through hysteresis comparator (7), phase discriminator (9) carries out the ring width that phase demodulation is controlled hysteresis comparator (7) to the signal of this PWM ripple and clock-signal generator (6) generation.Thereby finished frequency locking control.

Hysteresis comparator (7) is only exported a PWM ripple, is achieved for guaranteeing forced commutation, and each power tube must carry out timesharing and drive.The effect of the logic gating circuit (11) of synchronizing signal control is sent into corresponding power transistor isolated drive circuit (12) to a pwm signal respectively exactly, and the pulsating direct current of PWM rectifier output is through filter (14) output stable DC.

To the so asymmetric electronics pressurizer main circuit of accompanying drawing 2.Phase current has only positive controlled, thereby the three-phase current closed loop can be made a hysteresis comparator altogether.To the main circuit of full bridge structure, must be with the given given waveform of three-phase current that multiply by of electric current of Voltage loop output, with the waveform of three current closed-loops difference control output voltage.Again the structure and the basic principle of each several part circuit in the accompanying drawing 1 is further elaborated below.Can adopt accompanying drawing 2 this boost type circuits simple in structure for 120 ° of wide square-wave motors,, merge L at accompanying drawing 2 (b) ₁, L ₂And remove D ₂, in fact be exactly a parallelly connected step-up type DC/DC converter, figure (a) is depicted as circuit and changes jobs at the wheel that can regard six circuit shown in figure (b) in the one-period simply as.Its operation principle is, when the direct voltage of output during greater than rated output voltage, threshold circuit output low level, the switching signal of power transistor is cut, then power transistor T _A, T _B, T _CAll do not work, its system works is at the diode rectification state; When the direct voltage of output during less than rated output voltage, power transistor is devoted oneself to work, T _AAt 120 ° of the highest internal gating work of motor A phase voltage, T _BWith T _CPipe ends; At 120 ° of the highest internal gating T of motor B phase voltage _BThe plumber does, T _AWith T _CEnd; At 120 ° of the highest internal gating T of motor C phase voltage _CThe plumber does, T _AWith T _BEnd.

T _AWhen the plumber does, corresponding D _AThe pipe conducting is if at this moment negative group diode is D ' _BConducting, then motor A, B two-phase provide power supply to constitute the parallel connection boosting converter, if negative group is D ' _CThe pipe conducting, then motor A, C two-phase provide power supply to constitute the parallel connection boosting converter, with D ' _BSimilar during the pipe conducting.T _BWith T _CWhen the plumber does and T _AIt is similar that the plumber makes situation.

Therefore, this boost type electronic voltage regulator main circuit has following advantage:

1) utilized the motor leakage inductance, the volume weight of system can reduce.

2) structure of main circuit is convenient to realize that starting/generating is difunctional.

3) control to electric machine phase current can realize forcing commutation, reduces commutation overlap and power-factor angle, and realizes the direct FEEDBACK CONTROL of electric current in the power transistor.

Accompanying drawing 3 is synchronization signal detection circuits.With the sine wave is example, obtain 1-6 natural commutation point shown in accompanying drawing 3 (a), and produce 120 ° of square waves, need and detect and conversion two parts circuit, on detected object, also can be divided into voltage directly detection and motor position detection, voltage only is discussed here directly be detected.

Can find out from accompanying drawing 3 (a) and (b) the natural commutation point of three-phase voltage to be the three-phase line voltage zero crossing, input circuit does not have common place with main circuit and control circuit simultaneously, so synchronization signal detection circuit is isolation zero passage detection and logic conversion circuit.

Realize electrical isolation, mainly contain photoelectricity and isolate and two kinds of forms of electromagnetic isolation, present embodiment is only discussed the electromagnetic isolation form that adopts transformer, and the secondary of its transformer carries out line voltage zero-cross with integrated comparator and detects, transformer does not need delivering power, thereby can do as far as possible for a short time.The U of transformer secondary control _Ab, U _BcCan directly obtain U _AbThe acquisition of line voltage will be with a subtracter shown in accompanying drawing 3 (c).

Natural commutation point detects and obtains three risings, trailing edge, is respectively 1-4, and 2-5 and 3-6 square wave are shown in Fig. 3 (d).They can be become three synchronizing signals of 120 ° of broad pulses by the circuit shown in the accompanying drawing 3 (e).

Accompanying drawing 4 is parallelly connected step-up type direct current (DC-DC) converters, contains current detection circuit.The DC-DC booster converter main circuit that figure (a) detects for belt current, figure (b) are the electric current I on triode T and the diode D _SAnd I _DWaveform.

The basic functional principle of parallelly connected step-up type DC converter is:

When the T pipe is opened, the DC power supply voltage U _SBe added on the energy storage inductor L,, have if omit the conduction voltage drop of triode $U_S=L\frac{{\mathrm{di}}_L}{\mathrm{dt}}$ So inductive current I _LRise, by the electric current I of triode _SIdentical with inductive current as Fig. 4 (b).Triode T turn-offs, and electric current reduces to zero, and it is constant that energy storage inductor L will keep electric current, and the induced potential on the inductance is reverse, as this electromotive force and U _SSum is greater than the voltage on the output capacitance C, diode D conducting afterflow, and the energy storage on the inductance flows to output capacitance and load by D, thereby makes output voltage U ₀For $U_0=U_S+L\frac{{\mathrm{di}}_L}{\mathrm{dt}}$ As seen U ₀Greater than U _S, reach the purpose of boosting.The inductive current linearity reduces during the diode continuousing flow, and when the T pipe was opened once more, inductive current rose again, and load current is provided by the electrochemical capacitor C of energy storage during T opens.The continuous switch of T pipe remains unchanged output voltage, and the height of output voltage is relevant with the conduction ratio η of triode, and fundamental relation is: $U_0=\frac{U_S}{1-\mathrm{\η}}$ $\mathrm{\η}=\frac{T_{\mathrm{ON}}}{T_{\mathrm{OFF}}+T_{\mathrm{ON}}}$ T in the formula _ONAnd T _OFFBe opening and deadline of triode.

Operation principle according to above-mentioned parallelly connected step-up type DC-DC converter constitutes DC permanent-magnetic brushless generator.Difference is to carry out logical process according to the different rotor position of magneto alternator on the principle, allows corresponding D C-DC booster converter wheel change jobs, thereby stablizes output dc voltage.

In accompanying drawing 2 (b), during the transistor T conducting, the two-phase induction motor winding is utilized the inductance in the motor windings to make energy-storage travelling wave tube by instantaneous short-circuit accordingly, and the armature winding electric current increases, and energy storage simultaneously also increases, and when the T pipe ended, inductive current passed through D ₁, D ₂Afterflow, and be output capacitance C and electric.The transistorized conduction ratio η of power controlling is stabilized in rated value with VD.The present invention has solved the output voltage of permanent magnet generator effectively and has regulated problem.

Accompanying drawing 4 is as current detection circuit.To carry out isolation detection to the electric current on the three-phase energy storage inductor, and with the modulation work that this current feedback signal comes control circuit, current detection circuit proposed following requirement:

1) electrical isolation is promptly isolated main circuit and control circuit;

2) has wider frequency, at 0～2f _MaxInterior current detecting multiplication factor will remain unchanged f substantially _MaxBe maximum modulating frequency;

3) testing circuit will have wide as far as possible linear work district, avoids saturation distortion, obtains high as far as possible current detecting sensitivity;

4) higher antijamming capability;

5) on the basis that reaches above-mentioned each requirement, make every effort to circuit structure simply, reliably.

For reaching above-mentioned requirements, can adopt photoelectricity to isolate current detection circuit and electromagnetic isolation current detection circuit.Be that example is illustrated only below with the electromagnetic isolation current detection circuit of accompanying drawing 4.Being applicable to that the current transformer of work under the exchange status is used for the boost pressure controller of direct current character, is the working mechanism that has utilized adjuster.Shown in figure (b).

i _L＝I _S 0＜t＜T _ON

i _L＝I _D 0＜t＜T _OFF

This circuit is used two current transformer CT respectively ₁, CT ₂Detect electric current I _S, I _D, and then through scheming the instrument transformer secondary circuit of (a), I _S, I _DSignal is at R ₀Go up and synthesize, thereby reappeared i _LWaveform, its operation principle is as follows:

t ₁＞t＞t ₂The time, there is I _SElectric current, CT ₁The electromotive force of being responded to makes D ₁Conducting, R ₀On the detection output signal reflected I _SSize.At t ₂Triode turn-offs constantly, I _SBe forced to zero, CT ₁Secondary induction reverse potential makes D ₁Manage reverse instantaneous afterflow, thereby discharge CT ₁Interior energy, the iron core magnetic state recovers, and is I next time _SDetection is got ready.At t ₂Constantly, because I _DThe transition of electric current makes D ₂Conducting, R ₀On reflected electric current I again _DThereby, reappeared i _L

Can find out R from the analysis of above operation principle ₀Be to detect resistance, current signal is converted into voltage signal.C ₀Be output filter capacitor, the change of current spike when detecting in order to inhibition is guaranteeing U ₀Under the less situation of spike, τ ₀=R ₀C ₀Should select lessly, to guarantee to detect rapidity and C ₀The high band that causes incorporated into detect distortion.D ₁, D ₂Effect be to allow instrument transformer CT respectively ₁, CT ₂Forward current pass through, and make the reverse recovery dissipative cell of instrument transformer, therefore should select the fast diode of high back-pressure for use, make oppositely recover fast when detecting, to detect distortion little.The core material of instrument transformer also should be selected the annular core of high permeability for use, and requires that its magnetic hysteresis loop is narrow, the linearity good, and working band is wide.

The electromagnetic isolation testing circuit is compared with the photoelectricity isolation detection circuit, has that line construction is simple, reliable, buffer action is good, low cost and other advantages.

Accompanying drawing 5 is an isolated drive circuit.The basic demand that high-performance drives will be carried out electrical isolation exactly.Shown in the accompanying drawing 5 is an employing impulse control method isolated drive.This circuit has utilized a little and simple pulse transformer CT to transmit and has opened, cut-off signals, and driving stage is by a flip and flop generator memory switch order, and the bistable output signal is amplified and driven main circuit power transistor T through driving output stage again _A, T _BOr T _CWork.

Input produces the pulse signal of two 0.5～2 μ s, makes that the isolating transformer volume is little, and irrelevant with modulating frequency.T ₁, T ₂Constitute flip and flop generator, T ₂Pipe is because D ₁, D ₂The anti-saturation effect be operated in the quasi saturation state.T ₁Guan Weiyi undersaturated current source.Therefore this circuit can overturn soon, has satisfied the very fast rising of drive signal needs, the requirement of trailing edge.D in the circuit ₇～D ₉Effect be the high level stability that guarantees bistable circuit, prevent T ₁Base current is paid the limit bypass from transformer, improves the antijamming capability of circuit.

Because pulse transformer does not need transmitted power, available TTL or MOS gate circuit Direct Transform drive signal output to the transformer two ends, for improving the reliability of input stage, the differential circuit pulse transformer of also available band triode.

In the accompanying drawing, the circuit of its dotted portion has constituted self adaptation, and self-shield drives.R ₁, R ₂Dividing potential drop A point current potential when being provided with conducting, during operate as normal, power transistor (T _A, T _BOr T _C) C point current potential be lower than A point current potential, R ₆On electric current through D ₃Flow to power tube, during owing to load short circuits or drive current deficiency, power transistor (T _A, T _BOr T _C) U _CesRise, work as U _C=U _AThe time, D ₄Conducting, A point current potential raises, and power transistor (T has been turn-offed in the bistable circuit upset in time _A, T _BOr T _C), thereby prevented the transient state overcurrent and the overheated breaking-up of power transistor effectively.

In fact, even under the situation of operate as normal, the saturation voltage drop U of power transistor _CesAlso will be with I _CThe growth of electric current and increasing, thereby can pass through U _AI is carried out in the setting of voltage _COvercurrent protection greatly improves system reliability.

In sum, pulse controlled electromagnetic isolation drives following advantage:

1) providing protection fast and effectively to overload and short circuit, is a kind of quite safe drive circuit.

2) pulse is narrow, and volume of transformer is little, only transmits switching signal, and transmission delay is little.

3) shaping after bistable circuit has been realized isolating has comparatively ideal driveability.

4) circuit structure is simple, and cost is low.

Accompanying drawing 6, voltage regulator circuit---be pi regulator.

Actual pi regulator should have K _P, τ ₁Adjustable form, the design of circuit structure should be satisfied the condition of amplifier works fine, guarantees K _P, τ ₁Adjustable flexibly.A kind of basic pi regulator embodiment circuit diagram has been shown in the accompanying drawing 6.Its transfer function is: $G\left(S\right)=\frac{U_0\left(S\right)}{U_i\left(S\right)}=-[R_F+\frac{1}{C_{F}S}]/R_f=\frac{R_F}{R_f}\·\frac{1+R_F{C}_{F}S}{R_F{C}_{F}S}$ As seen:

Like this, change R _fRegulate K _P, change C _FScalable τ ₁

In current closed-loop, play PWM modulation work, the critical component of decision modulating frequency is a hysteresis comparator, and the actual characteristic of comparator plays decisive influence to the work of system, and shown in the accompanying drawing 7 (a) is the circuit diagram of permanent ring width hysteresis comparator.Its capacitor C value is about 100PF, and its effect is the positive feedback that strengthens the comparator transfer process, improves the switching rate of amplifier, and has according to the amplifier condition of work: R=R _t∥ R _f

If with the positive feedback resistor R in the accompanying drawing 7 (a) _fReplace with a controlled feedback resistance, can realize the hysteresis comparator that ring width is controlled.Accompanying drawing 7 (b) is that the employing spaning waveguide operational amplifier is the hysteresis comparator of feedback network.

In the brushless DC generator control circuit, the constant frequency circuit is by clock generator, and phase discriminator and low pass filter are formed.Constitute the frequency closed-loop control with hysteresis comparator, form phase-locked loop.

Clock generator can be by time-base circuit CD555, and gate circuit or amplifier constitute simple clock generator.Not high according to frequency stability in this system, the demanding characteristics of phase demodulation rising edge select for use simple CMOS gate circuit to constitute clock generator, shown in accompanying drawing 8 (a).

Utilize the phase comparator in the CMOS phase-locked loop CD4046 that phase demodulation is carried out in comparator output and clock forward position, finally reach frequency stabilization and phase-locked purpose, the logic diagram of phase discriminator is shown in accompanying drawing 8 (b).

Phase demodulation is exported the slow ring width of controlling hysteresis comparator by a low pass filter and driving stage, realizes the frequency stabilization modulation.Its circuit diagram is shown in accompanying drawing 8 (c).For common phase-locked loop, not tight because the control end of voltage controlled oscillator (VCO) do not consume energy to the requirement of low pass filter, time constant filter τ=R ' C (R '=R ₁+ R ₂) design should trade off and should avoid loop to enter self-excitation, guaranteeing again has fast response speed rationally to the variation of incoming frequency.Usually best work is resistance R ₂Resistance be R ₁10～30%, get R ₁=470k Ω, R ₂=47k Ω, C=0.1 μ F, its frequency lock-in range is the operation interval of whole voltage controlled oscillator.

The present invention can be applied in the power supply in fields such as aircraft, warship, tank, steamer, automobile.

Claims (1)

1. a permanent-magnet brush-free DC generator with electronic voltage stabilizer is by permanent magnet generator, by the synchronizing signal isolation control circuit, analog switching circuit, current detection circuit, reference voltage circuit, voltage detecting circuit, voltage regulator circuit, current regulating circuit, logic gating circuit, the control device that isolated drive circuit is formed and the output filter circuit of main circuit, it is characterized in that, its electronic voltage regulator main circuit of monophase machine is connected into single-phase rectification bridge output by 4 diodes, 2 power transistors are parallel to respectively on two diodes of single-phase rectification bridge minus side, its electronic voltage regulator main circuit of three phase electric machine is connected into three-phase commutation bridge output by 6 diodes, 3 power transistors are parallel to respectively on three diodes of three-phase commutation bridge minus side, make when generator speed equals maximum (top) speed by means of described control device, power transistor in parallel is in off state, electronic voltage regulator is fully operational in the rectification state of diode, make bridge rectifier be output as the direct current of rated voltage, when the rotating speed of generator is lower than maximum (top) speed, boost power transistor work in parallel is brought up to load voltage value with VD.

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