Bipolar great power pulse power source
The present invention relates to a kind of pulse power, in more detail, relate to a kind of bipolar great power pulse power source.The pulse power of the present invention is mainly used in coating metal surface generation oxide ceramic layer in differential arc oxidation method, especially be useful in the differential arc oxidation method of aluminium, magnesium, titanium, Zirconium, beryllium, tantalum and their alloy surface generation ceramic layer, also can be used for the occasion that other needs bipolar great power pulse power source.
In recent years, because the ceramic layer that generates in the metal surface with differential arc oxidation method has good physics, chemical characteristic, with differential arc oxidation aluminium, magnesium, titanium, Zirconium, beryllium, tantalum and their alloy surface are carried out the method for ceramic treatment, in industrial departments such as automobile, Aeronautics and Astronautics, machinery, electronics, obtained using widely.In the method, one of key factor that the decision ceramic layer generates quality and speed is the Electric Field Characteristics that is applied to the metal surface, and this Electric Field Characteristics is again to be determined by the performance of the pulse power and working method.In the prior art, during with the anode oxidation method process metal surfaces, used power supply mostly is straight flow greatly or direct current adds the unidirectional pulse formula, and is LVPS.In the document of relevant differential arc oxidation method, the general only simple voltage waveform that is applied to the metal surface of introducing, the power supply that does not all have detailed place of matchmakers to adopt.In PCT/GB97/00664, introduced the AC power of a kind of 700V of being at least through waveform modification.It is a kind of single phase alternating current power supply that directly obtains big pulse current from electrical network of exporting again with after capacitor and the transformer series connection.Though this power supply is simple, but there are some disadvantages, fail to be convened for lack of a quorum as the very big single phase alternating current (A.C.) Pulse Electric that produces serious distortion through waveform modification electrical network is caused serious impact, bring the trouble of severe contamination electrical network, and the electrical network three phase supply is unbalanced, can't be used for industrial production.The capacitor of different numerical value can be revised waveform though connect, and has also changed the numerical value of operating voltage simultaneously.Moreover the operating voltage amplitude can not be regulated continuously, has brought inconvenience to use.
The objective of the invention is to eliminate the weak point of the power supply that is used for differential arc oxidation in the prior art, a kind of three-phase equilibrium is provided, electrical network is not had to impact, do not disturb and pollute substantially, can be used in the industrial bipolar great power differential arc oxidation pulse power.
Another object of the present invention provides a kind of power supply of suitable differential arc oxidation work.It is that positive and negative pulse amplitude and width are continuously adjustable respectively; flat-top; bipolar great power pulse power source; by optimized choice to working pulse amplitude, width and frequency parameter; can guarantee to obtain best ceramic structure layer, good production efficiency and safety, reliably, operating characteristics easily.
The above-mentioned purpose of bipolar great power pulse power source of the present invention can realize by following measure:
Employing is through the three-phase equilibrium power supply of multiple line filter and transformer isolation, form the continuously adjustable high-power DC power supply of positive and negative two-way voltage respectively, again under the control impuls effect, the driving power switch element carries out the copped wave conversion respectively, obtains the continuously adjustable high-power positive and negative pulse of pulse duration.In the differential arc oxidation process, in order to generate the ceramic structure layer of high-quality in the metal surface, the voltage waveform of bipolar great power pulse is selected the square wave of flat-top for use, and the amplitude of pulse and width are adjustable continuously respectively.By optimized choice, under suitable oxide ceramics growth rate, can also save the energy effectively to positive and negative pulse amplitude of power supply and width.The present invention has taked special measure, allows in the three phase network each trigger in turn mutually and obtains output services pulse, makes electrical network three-phase equilibrium power supply, and electrical network is impacted and pollutes little.The main circuit power supply of power supply of the present invention adopts slowly and starts, and can make the oxidation gradually of new workpiece, helps forming high-quality ceramic structure oxide layer and can prevent capacitor and the load heavy current impact that unexpected full power power supply causes.The startup of pulse adopts gradual change to launch slowly, also adopts gradual change to launch slowly behind the pulse reset, thereby guarantees under whole operating states of power supply, electrical network is impacted little little with pollution.The described pulse power also adopts multiple protective, to guarantee the long-term safety steady operation.The described pulse power can also a tractor serves several purposes: can export the bipolar great power pulse, also can export the unipolarity highpowerpulse, can also be used as high-power DC power supply, to satisfy the demand of different user various uses.
The multiple protective measure of paired pulses power supply of the present invention comprises the following aspects: (1) utilizes the current transformer sampling of string at transformer secondary output, limits gross power; (2) utilize the current sensor sampling of string in load, come the range value of power-limiting switching tube pulse current; (3) pressure drop that utilizes power switch pipe comes power-limiting switching tube pulse current to be no more than limiting value as overcurrent sample; (4) utilize temperature switch, realize overtemperature protection copped wave transform power switching tube.
Owing to adopted multiple protective, guaranteed the fail safe of power supply long-term work.
The advantage of bipolar great power pulse power source of the present invention is when being used in the differential arc oxidation process metal surfaces, the ceramic structure layer of high-quality can be provided, electrical network is not had substantially to impact, do not disturb and do not pollute, and three-phase equilibrium can long-time safe and stable operation in industrial production.
To be embodiment as mao power source, the invention will be further described below in conjunction with accompanying drawing.
Fig. 1 is the bipolar great power pulse power source theory diagram;
Fig. 2 is a copped wave conversion schematic diagram;
Fig. 3 is for acting on pulse voltage and the pulse current waveform in the load (for example needing the metal works of plating);
Fig. 4 is the controllable silicon voltage stabilizing dc positive power block diagram of slow start-up control;
Fig. 5 is the controllable silicon voltage stabilizing dc negative supply block diagram of slow start-up control;
Fig. 6 is the theory diagram of pulse control circuit;
Fig. 1 shows the theory diagram of this bipolar great power pulse power source:
380 volts of three-phase alternating currents divide two-way through line filter, deliver to positive supply primary and negative supply primary respectively, transformer secondary output output is delivered to the three-phase controlled rectification bridge through line filter again, rectification is after inductance, capacitor filtering, sampling, trigger voltage stabilizing circuit control through the controllable silicon phase shift, obtain 0-+800 lie prostrate continuously adjustable dc positive power (+V) and 0--300 lie prostrate continuously adjustable dc negative supply (V), then, respectively under the control impuls effect of pulse control circuit output, carry out the copped wave conversion through the power switch inverter of chopping, obtain just needed, negative pulse.
Fig. 2 is a copped wave conversion schematic diagram:
Under the control impuls effect, when the positive switch closure, the dc positive power powering load, when the positive switch disconnected, positive supply finished electric, and the time of positive switch closure is the duration of positive pulse; In like manner, under the control impuls effect, during the negative power switch closure, the dc negative supply powering load, when the negative power switch disconnected, negative supply finished electric, and the time that the negative power switch closes is the duration of negative pulse.
Fig. 3 is through acting on the pulse voltage and the current waveform that flows through load (micro-arc oxidation workpiece) in the load (micro-arc oxidation workpiece) after the copped wave conversion.
Fig. 4 is the controllable silicon voltage stabilizing dc positive power block diagram of slow start-up control;
It is basic identical that it and general controllable silicon phase shift trigger voltage stabilizing circuit, do not exist together is to have increased slow start-up control partial circuit, after starting high pressure or pressing reset button, slow start-up control is partly exported a slowly linear voltage signal that rises, isolate through follower, be applied to three phase-shift control circuit inputs by clamping diode, the control thyristor operating angle is opened gradually, the DC power supply output voltage is started from scratch and is slowly risen, have only when the voltage of sampling after relatively reaching error and amplifying and be lower than slow start-up control voltage, be no longer conducting of clamping diode, when whole system entered closed loop voltage regulator state, slow start-up control part no longer worked.At this moment, power supply enters the voltage stabilizing operating state of setting.
Fig. 5 is the controllable silicon voltage stabilizing dc negative supply block diagram of slow start-up control;
It is basic identical with the controllable silicon voltage stabilizing dc positive power of slow start-up control, just after negative sampling voltage, added the one-level phase inverter, it will bear the sampling voltage paraphase becomes positive voltage, delivers to the second level again and reference voltage compares, and its error goes to carry out the voltage stabilizing adjustment after amplifying.
Fig. 6 produces theory diagram for control impuls:
In order to allow each triggering acquisition output services pulse in turn mutually of three phase network, make electrical network energy balanced feeding, and in order to reduce the impact to electrical network, ideal method is to allow the frequency of output services pulse and electrical network that certain synchronized relation is arranged.The present invention delivers to A, B, C three-phase ac signal three zero cross detection circuits (A phase zero passage detection, B phase zero passage detection, C phase zero passage detection) respectively with three small transformers, obtain the zero-crossing pulse of three group of 100 cycle per second, again they are delivered to the adder circuit addition, thus obtain 300 cycle per seconds with mains frequency the lock-out pulse of certain relation is arranged.Choosing appropriate frequency dividing ratio (be the 2n frequency division, n is a positive integer) just can allow three phase network respectively trigger the pulse of acquisition output services mutually in turn.The T trigger is delivered in pulse behind frequency division, two outputs (Q, Q) at the T trigger obtain complementary level, so just can divide two-way to produce and the corresponding triggering control impuls of the positive and negative pulse of output, the purpose of inserting delay circuit in two-way is can be in after power supply controllable silicon blocking interval or the filter capacitor boost charge for the moment that allows trigger impulse produce, reaching the effect of energy storage type power pulser, thereby avoid electrical network is produced big impact.Add slow broadening start-up control in positive and negative pulse width regulating circuit respectively, it can avoid starting and the work of the restarting big pulse current impact just that resets.
The bipolar great power differential arc oxidation pulse power of the present invention is provided with multiple protective and warning, can guarantee reliablely and stablely to move for a long time.
Its performance index are: 1. VD:
Positive supply is 0 to+800 volt (adjustable continuously);
Negative supply is 0 to-300 volt (adjustable continuously); 2. average anode current:
Positive supply is 150 peaces to the maximum;
Negative supply is 150 peaces to the maximum; 3. voltage pulse output amplitude:
0 to+800 volt of positive pulse voltage amplitude (adjustable continuously);
0 to-300 volt of negative pulse voltage amplitude (adjustable continuously); 4. output maximum surge current: 1000 peaces: 5. pulse duration: 0 millisecond to 3 milliseconds (adjustable continuously); 6. pulse frequency: 150,75,37.5,18.75 cycle per seconds;
Should point out emphatically, below only by the description of schematic diagram to being described property of this pulse power, concerning one of skill in the art, will expect various corrections in spiritual scope of the present invention and additional, only otherwise depart from the given feature of purpose of the present invention, all variations in the scope that the equivalence of the claim of invention forms all should be included in the present invention.Protection scope of the present invention is determined by following claim.