CN103026784B - Magnetron power source - Google Patents

Abstract

Power supply for magnetron has high-voltage converter (101), microprocessor (103) and resistance (109).High-voltage converter includes integrated circuit oscillator IC1, switching transistor T1, T2, inductance L1, transformator (106) and commutator (107).The D/C voltage increased is supplied to transducer (101) by voltage source (4).Be configured with the operational amplifier (122) of the error amplifier of integrating capacitor C7 and resistance R9 by from microprocessor (103) control signal and resistance (109) compares and by output signal supply to agitator IC1.Agitator IC1 controls switching transistor T1, T2, and the output of switching transistor T1, T2 is connected to inductance L1 and the primary coil of transformator (106).The secondary coil of transformator (106) is connected to half-bridge diode D3, D4, D5, D6 and electric capacity C5, C6 to provide the DC electric current from transformator to magnetron (102).

Description

Magnetron power source

Technical field

The present invention relates to the power supply for magnetron, particularly but not exclusively for the magnetic control powered to lamp Pipe.

Background technology

Known magnetron may change pattern undesirably, say, that magnetron may exist undesirably Stop oscillation at one frequency and at another frequency, start vibration.In these cases, magnetron can Negative impedance can be presented.This may cause the high electric current being harmful to.To such end it is known that constant/controlled voltage power supply pair For magnetron improper, and constant/controlled current flow power supply is generally used for being powered magnetron.

Anode voltage in magnetron is high, and the measurement of anode voltage and anode current is difficult.

In the power supply of former present inventor invention, the voltage of the transducer in supply magnetron power source and stream The measurement of the electric current crossing transducer is used in combination the power to supply magnetron and provides real with pico computer Time control.Pico computer is programmed to calculate:

1. the power consumed,

2. with expectation power difference, and

3. the difference between difference power and measured electric current.

This second difference signal is used for controlling transducer.It should be noted that, these three step performs in software. Undesirably, this power supply still suffers from a certain degree of instability, causes the lamp institute powered by this magnetron The perceptible flicker of the light produced.

Now experiment has shown that the optical flare in the plasma lamp that eyes are powered for magnetron extremely Sensitive.Have appreciated that now that finite speed and the resolution of microprocessor fan-out capability make to be perceived Flicker deteriorate.Additionally, to two inputs in the input of microprocessor, i.e. apply the electricity to transducer Pressure and flow through the electric current of transducer and be prone to that noise occurs, and being multiplied of two noise signals is considered to promote Unstability.

The simple filtering to noise from microprocessor unacceptably reduces the reaction of control circuit Time and promote unstability, the fast reaction needed for the magnetron situation changed to be kept firmly in mind. It is thus desirable to new method.

Summary of the invention

It is an object of the present invention to provide the power supply for magnetron of a kind of improvement.

According to the present invention, it is provided that a kind of power supply for magnetron, including:

DC voltage source；

Transducer, for raising the output voltage of described DC voltage source, described transducer has:

Capacitor and inductor resonance circuit,

Switching circuit, is suitable to drive with the variable frequency more than the resonant frequency of described resonance circuit Described resonance circuit, wherein said variable frequency is inputted by control signal and controls to provide friendship Stream voltage,

Transformator, be connected to described resonance circuit for raise described alternating voltage,

Commutator, the D/C voltage after the ac voltage rectifier after raising to rising is to apply To described magnetron；

For measuring the parts of the electric current flowing through described transducer from described DC voltage source；

Microprocessor, is programmed to produce the control letter of the desired output power representing described magnetron Number；And

Integrated circuit, is configured and adapted to according to the signal from current measuring members in feedback loop mode With relatively control signal being applied to transducer switching circuit of the signal from described microprocessor, with The power of described magnetron is controlled as described expectation power.

Integrated circuit is set and provides quick control ring as the discrete elements separated with microprocessor, this ring Do not limited by the speed of microprocessor.(specification of microprocessor used is due to its speed of reason of Financial cost Degree is the slowest.) thus the power supply of the present invention is the most stable and provides less flicker Illumination.

Simultaneously, it is contemplated that integrated circuit can be digital device, in order to save, dress is preferably simulated Put.In a preferred embodiment, integrated circuit is operational amplifier.

In a preferred embodiment, operational amplifier is configured with the integrator of feedback capacity, its output Voltage is suitable to control voltage to frequency circuit to control transducer.

Preferably, microprocessor is programmed to be filtered the noise of expectation converter current signal.Can Selection of land, filter circuit can be arranged between microprocessor and operational amplifier.

In a preferred embodiment, switching circuit is controlled according to the variable voltage signal exported from operational amplifier The frequency of transducer processed.In the art, the increase of frequency and driven by magnetron power and microwave export Reduce corresponding.

Alternatively, switching circuit is suitable to control the dutycycle of transducer according to operational amplifier output, its The reduction that the reduction of middle dutycycle exports with driven by magnetron voltage and microwave is corresponding.

In a preferred embodiment, transducer is zero voltage switching device；Although transducer can be zero current Switching device.

Generally, switching circuit has the agitator of oneself；It is contemplated, however, that switching circuit can root Timing is carried out according to the clock of microprocessor.

In one embodiment, integrated circuit was suitable to and is configured in measured current signal and phase Hoping and compare between power signal, integrated circuit is connected only to receive these signals, thus with DC The transient change of the voltage of voltage source independently controls converter current according to described expectation power.This reality Execute example to control mean power for constant on voltage source period of waves.

In another embodiment, integrated circuit is suitable to and is configured not only at measured current signal And compare between expectation power signal, it is also contemplated that the transient change of the voltage of DC voltage source, the most defeated Entering the signal of the voltage representing voltage source to described integrated circuit, wherein converter current is controlled as root The power by described transducer is controlled according to described expectation power.The present embodiment is in voltage source period of waves Middle is constant by instantaneous power control.

Generally, switching circuit has the agitator of oneself；It is contemplated, however, that switching circuit can root Timing is carried out according to the clock of microprocessor.

Accompanying drawing explanation

In order to help to understand invention, now by by way of example and be described with reference to the attached figures the present invention's Specific embodiment, wherein:

Fig. 1 is the block diagram of the power supply for magnetron of prior art；

Fig. 2 is the similar block diagram of the power supply according to the present invention；

Fig. 3 is the more detailed circuit diagram of the power supply of Fig. 2；

Fig. 4 is the skeleton diagram of the lamp powered by the magnetron of the power supply with the present invention；

Fig. 5 is the circuit diagram of the second embodiment of the present invention；

Fig. 6 is the details of the potentiometer of the embodiment of Fig. 5；

Fig. 7 is the spectrogram of the magnetron output that the embodiment of Fig. 3 and 5 compares；And

Fig. 8 is the circuit diagram of the third embodiment of the present invention.

Detailed description of the invention

With reference first to Fig. 1, showing the power supply of prior art with graph mode, this power supply has agitator 1, this agitator 1 is connected to power magnetron 2 and controlled by microprocessor 3.The power supply increased 400 volts of voltages are generally supplied to agitator 1 on circuit 5 by voltage, i.e. DC voltage source 4. This by alternating current supply to transformator 6 and commutator 7, from transformator 6 and commutator 7 by 4000DC Volt applies to magnetron on circuit 8.Agitator, transformator and commutator are referred to as " high pressure conversion Device ".The power of supply magnetron is measured with the voltage at resistance 9 two ends in the earth-return circuit of transducer. Assuming that from the case of the voltage constant of voltage source 4, this voltage can represent the electric current in resistance 9 and It is directly proportional to the power of supply magnetron.The voltage of resistance is on the circuit 10 of microprocessor Input.Voltage on circuit 5 is applied to microprocessor by another input on circuit 11.From outside or Desired power control value 12 is arranged microprocessor with manual input-mode by person.

Microprocessor is programmed to follow the steps below:

1., in the case of supposition is high efficiency, the voltage on circuit 5 is multiplied to the electric current in resistance 9 The power of calculating magnetron to be supplied；

2. the power to be consumed calculated is compared with expectation power, thus calculate and disappeared The electric current (expectation electric current) of consumption；

3. compare expectation electric current and measured electric current, if this electric current is high, then apply the electricity being gradually increased The power supply of pressure to drive transducer with higher frequency, or, if this electric current is low, then apply gradually to drop The power supply of low voltage.It should be noted that if transducer is with higher frequency work, then at magnetron two Voltage obtained by end reduces.

As already mentioned, this circuit is proved in use flicker free for the magnetron as light source For operation the most unstable.

Turning now to Fig. 2, the power supply of the present invention includes the following similar assembly connected in the same manner:

Agitator/high-voltage converter 101；

Magnetron 102；

Transformator 106；

Commutator 107；

Resistance 109.

Also include microprocessor 103, but microprocessor 103 operates in the way of very different.Micro-place Reason device 103 only will expect the power control value 112 mains DC voltage divided by the increase on circuit 105, And on circuit 121 provide represent flow through transducer 101 expectation electric current required current signal come with Expect power operation magnetron.Signal on circuit 121 is supplied one of operational amplifier 122/EA1 Input.Another input of operational amplifier 122/EA1 is from resistance 109 to operational amplifier The circuit 110 of 122/EA1, represents the actual current flowing through transducer.Operational amplifier is connected into work For cumulative error signal amplifier.

Turning now to Fig. 3, it is shown that whole circuit diagrams of the power supply of Fig. 2.Central authorities are high-voltage converters Quasi-resonance agitator 101, it has MOSFET field effect switching transistor T1, T2.Utilize integrated Circuit oscillator IC1 switching mosfet field effect in the following manner switching transistor T1, T2.Transformation The inductance L1 of device 106 and primary coil are connected to the common point of transistor T1, T2.Electric capacity C3, C4 completes series resonant circuit.Inductance and electric capacity determine resonant frequency, transducer this resonant frequency it Upper work, resonant frequency is typically at about 70kHz, thus, about the magnetron circuit in downstream, its Seem mainly inductive circuit.This includes four half-bridges diode D3, D4, D5, D6 and smooths Electric capacity C5, C6, they are connected to the secondary coil of transformator and provide DC electric current to magnetron 102.The coil ratio of transformator is 10:1, thus, applies the voltage of 4000 volts of ranks to magnetron, The mains DC voltage of the increase on circuit 105 is usually 400 volts.

The feature of converter circuit be when transistor T1, T2 sequentially connected and after be sequentially disconnected Time, in inductance L1, the energy of storage makes the voltage inversion at its two ends.This reduced before TR2 connects Voltage at common point C and improved common point voltage before TR1 connects.Thus switching occurs The voltage at transistor two ends to be connected is zero volt or close at zero volt, i.e. at ZVS In (Zero-Voltage-Switching, zero voltage switching) pattern.This facilitate reliability and long-life.

With high switching frequency (that is, exceeding resonance), the electricity at common point between electric capacity C3, C4 The half of the voltage that pressure is substantially constant on circuit 105, thus, when transistors switch, substantially Slope current for triangular waveform flows through inductance L1.Electric current passes through transformator, eventually arrives at magnetic afterwards Keyholed back plate.

Operating frequency is reduced to increase closer to resonance the voltage swing of D, the electricity in route deflection 105 The half of pressure, and increase the voltage at magnetron, the electric current of magnetron and microwave output thereof.

At the resistance 109/R1 of generally 100m Ω, measure the electric current flowing through transducer, indicate this electric current Voltage be generally 470 Ω via feedback resistance R5() be transferred to an input of operational amplifier 122 End 123.Microprocessor 103 receives the voltage from circuit 105 via potentiometer R3, R4.Via It is manually entered end 112 and required power setting is set.Microprocessor is programmed to power demand divided by line Road voltage and the resistance R10 via 6k Ω will indicate the converter current that required magnetron needs Voltage applies another input 125 to operational amplifier.Operational amplifier has integrating capacitor C7, long-pending Electric capacity C7 is divided to be generally 470nF and connect with the resistance R9 of 1M Ω.The ratio of resistance R9, R10 is true Determine the gain of operational amplifier.This is again set at the most feasibly suppressing supply voltage to flash.Amplify The integral voltage of instruction power demand is sent to the frequency control circuit 126 for agitator IC1 by device, It is voltage to frequency circuit (IRS2153 or the ST Thomson of typically Texas Instruments L6569).Including 18k Ω resistance R2, be all electric capacity C1, C2 and the diode of 470pF The circuit of D1, D2 is used for controlling the frequency of transducer.When the output of operational amplifier is zero, electric capacity C1 with C2 is in parallel, and obtains low-limit frequency.This is corresponding with maximum magnetic flux keyholed back plate power.On the other hand, When output is maximum, diode is not turned on and frequency is individually by C2 control.Peak frequency and most is provided Small-power (ranks of maximum 1/10th).At medium voltage, C1 has an intermediate effect, and because of This controls frequency and power.

Operate thus, it is possible to control magnetron with the expectation power of input to microprocessor.Microprocessor Easily by the flicker effects of the change in voltage caused on circuit 105.But, to R10 signal can including Portion by software filtering or in outside by unshowned RC filter filtering.If magnetron power consumption offsets, Because magnetron changes and power consumption skew along with its magnet heating and its resistance, operational amplifier is to resistance The change fast reaction of the electric current measured at R1 and adjust the frequency of transducer, therefore with circuit 125 On signal independently from microprocessor correction magnetron power consumption.

If it is to say, there is flicker on voltage source circuit, then the power of magnetron is only in flicker week It is constant when being averaged on the phase.Due to the cost of big smoothing capacity, this tends to doubling at voltage source Supply frequency flicker on circuit.

It should be noted that, above-mentioned power supply is particularly suitable for controlling such as the LER described in WO 2009/063205 Magnetron is for electric light.It make lamp light output the most as required from for bias light low-level to Total power illuminates entirely.

Fig. 4 shows and is represented by the simplification of the lamp of driven by magnetron.It has transparent crucible 201, should Crucible 201 has faraday cup 202.Hollow 203 in crucible has can the implant 204 of excitation material. Magnetron 205 is configured to be projected to its microwave waveguide/transition 206, and microwave is from waveguide/conversion On coaxially connected 207, outgoing is to antenna 208, by microwave release to crucible for conduit 206.Utilize this The power supply of magnetron is made by the power supply 209 of invention can excitation material luminescence.The power supply of the present invention is for keeping away It is favourable for exempting from this optical flare.

Turning now to Fig. 5, it is shown that according to the high-voltage converter of the improvement of the present invention.It not only allows for The change of converter current and the change of magnetron current thus caused, it is also contemplated that voltage source defeated Go out the mains frequency ripple mains frequency ripple of twice (or more accurately) of end.This fluctuation will not be led Cause the perceptible flicker of the light from LER, but the bandwidth of the output of magnetron really can be caused to expand Exhibition.

The deformation of Fig. 5 is the resistance R6 including two 1M Ω resistant series forms, and it is from voltage source line Being connected to opamp input terminal 123, feedback resistance R5 is connected to opamp input terminal 123. Resistance R6-R5 forms potentiometer.Potentiometer make the voltage at resistance R5 two ends substantially with current measurement The voltage at resistance two ends is identical, typically, in the case of opamp input terminal is 200mV, This voltage is all the rank of 100mV.Virtual voltage is along with the actual current in transducer and voltage source line On virtual voltage and change.It will be appreciated that the 200mV caused owing to the voltage in voltage source line increases Opamp input terminal increase by the operation amplifier with the 200mV caused due to the increase of electric current The increase of device input is suitable.The integral output voltage both making operational amplifier improves, and result is Reduce controlled current flow.

Will by the actual increase of the opamp input terminal caused by the increase of 5% in voltage source voltage Being 5%, because compared with voltage source voltage, the voltage at current measurement resistance two ends is little.With electric current 5% Increase equal, the voltage at current measurement resistance two ends will be 5%.It is defeated that it will be added to operational amplifier Enter the voltage at end.Thus, in voltage or electric current 5% or the increase of other little percent, electricity Flow and will reduce identical percent.

Thus, which results in 5% or the reduction of other little percent applying the power to magnetron. Thus, this power invariability being configured to keep moment.In this respect, use " moment " meaning be The cycle of the voltage pulsation of moment keeps power invariability.

This operation can be mathematically by description below:

The power of magnetron is voltage source voltage U and the product of converter current I, i.e. P=U × I.

In view of the unit of voltage and current, u and I:

P=(C₁×u)×(C₂×i)

P=K×(u×i)

In the case of u and i has unit value, this formula can be write as again

P=K×(u+i)/2。

This relational expression keeps near for the little change (such as u ± δ u, i ± δ i) of voltage and current As correctness.

Above equation can be rewritten as P=K₃+K₄×δV+K₅×δv。

Thus, the power of magnetron can be represented as constant plus another constant be multiplied by virtual voltage source with Arbitrary deviation of its rated value is added another constant and is multiplied by arbitrary deviation of electric current and rated current.Electricity Stream deviation itself can be represented as the voltage at current measurement resistance two ends.

Utilize suitable constant, and only consider to input the change to operational amplifier, it can be seen that point Depressor is by voltage source voltage and the sum of two changes of converter current, and input is to operational amplifier.Only have Premise be approximation

P=U×I≈K×(u+i)/2

Described approximation is just met during the voltage approximately equal at the only voltage at R5 two ends and R1 two ends.Pin Values below is met described approximation:

U=400 volt

Rl=0.1Ω

R5=470Ω

R6=2ΜΩ

These resistance are connected in figure 6 and are illustrated, further it is shown that associated voltage.

It should be noted that, because R6 than R1 big 7 orders of magnitude, and R5 than R1 big 4 orders of magnitude, So the arbitrarily change producing the U of the foreseeable change of the voltage of opamp input terminal is impossible Causing the foreseeable change of the voltage at R1 two ends, the voltage at R1 two ends is only by the electric current control flowing through R1 System.Therefore, the voltage at R1 two ends is added to the voltage at R5 two ends, and by they and input extremely Operational amplifier.

It will be appreciated that this mode of operation is not exclusively linear, but it really provides and is significantly improved. With reference to Fig. 7, it is shown that the saddle figure of the bandwidth of the frequency of the generation of magnetron.The generation frequency of magnetron Depend on the electric current flowing through it, magnetron be characterised by its control its two ends voltage on have with together Receive characteristic as diode-like.Thus, if more power is for magnetron, then its electric current increases, And operation frequency reduces.In the case of the voltage of voltage source has the fluctuation that supply voltage is relevant, Magnetron frequency changes and bandwidth presents the shape of slight saddle.As a comparison, by Fig. 5's The power of embodiment controls, and bandwidth is wanted much narrower and has Gauss distribution.Therefore this causing bluetooth to lead to Less interference aspect of communication network etc. is favourable.

Turning to Fig. 8, the input at operational amplifier illustrates multiplier circuit 301.Although digital device Be it is contemplated that, but this circuit is analog, and has and apply the R6-R7 to one input The midpoint of the common point of potentiometer and applying to the electricity from current measurement resistance R1 of its another input Pressure signal.The two voltage and current indication signal is multiplied and produces the letter representing magnetron power by multiplier Number, and it is applied to the input of operational amplifier.The present embodiment embodiment than Fig. 5 is more accurate, But more expensive, this is because multiplier circuit is rarely employed and costliness.It is considered that the enforcement of Fig. 5 Example is preferable, because it is the most accurate and the most less expensive.

Claims (18)

1. for a power supply for magnetron, including:

DC voltage source；

Transducer, for raising the output voltage of described DC voltage source, described transducer has:

Capacitor and inductor resonance circuit,

Switching circuit, is suitable to drive with the variable frequency more than the resonant frequency of described resonance circuit Described resonance circuit, wherein said variable frequency is inputted by control signal and controls to provide friendship Stream voltage,

Transformator, be connected to described resonance circuit for raise described alternating voltage,

Commutator, the D/C voltage after the ac voltage rectifier after raising to rising is to apply To described magnetron；

For measuring the parts of the electric current flowing through described transducer from described DC voltage source；

Microprocessor, is programmed to produce the control letter of the desired output power representing described magnetron Number；And

Integrated circuit, is configured and adapted to according to the signal from current measuring members with feedback loop form With relatively control signal being applied to transducer switching circuit of the signal from described microprocessor, with The power of described magnetron is controlled as described desired output power.

Power supply the most according to claim 1, wherein, described integrated circuit is analog.

Power supply the most according to claim 2, wherein, described integrated circuit is as error signal The operational amplifier that amplifier connects, described error signal is to represent the survey of the electric current flowing through described transducer The signal of value and represent described magnetron desired output power signal between difference.

4., according to the power supply described in claim 1,2 or 3, wherein, described integrated circuit is configured to Having the integrator of feedback capacity, the output voltage of wherein said integrated circuit is suitable to control voltage to frequency Circuit is to control described transducer.

Power supply the most according to claim 1 and 2, wherein, described integrated circuit is suitable to and is joined Being set to compare between measured current signal and expectation power signal, described integrated circuit is connected Connect only to receive these signals, wherein with the transient change independently basis of the voltage of described DC voltage source Described expectation power controls to flow through the electric current of described transducer.

Power supply the most according to claim 5, wherein, described current measuring members is and described turn The resistance of parallel operation series connection, one end ground connection of described resistance and the other end are connected to the defeated of described integrated circuit Enter end.

Power supply the most according to claim 6, wherein, the described other end of described resistance is via instead Feed resistance is connected to the input of described integrated circuit.

8. requiring the power supply described in 1 or 2 according to claims, wherein, described integrated circuit is fitted In and be configured not only to compare between measured current signal and described expectation power signal, Further contemplate the transient change of the voltage of described DC voltage source, represent that the signal of the voltage of voltage source is the most defeated Entering to described integrated circuit, the electric current wherein flowing through described transducer is controlled as according to described expectation power Control the power by described transducer.

Power supply the most according to claim 4, wherein:

Described current measuring members is and the resistance of described installed in series, a termination of described resistance Ground, and

The input of described integrated circuit is arranged potentiometer, and described potentiometer is included in described D/C voltage Two divider resistances between output rail and the ungrounded end of described current measurement resistance in source, two of which The points of common connection of divider resistance is connected to the input of described integrated circuit.

Power supply the most according to claim 9, wherein:

Described current measuring members is and the resistance of described installed in series, a termination of described resistance Ground, and

It is also provided with:

Potentiometer, is included in two points between output rail and the no-voltage rail of described DC voltage source Piezoresistance, and

Multiplier circuit, the voltage at described current measurement resistance is applied to a multiplier input End, and the voltage at the points of common connection of described divider resistance be applied to multiplier another Input, and multiplier output be applied to described integrated circuit with microprocessor export Compare.

11. according to the power supply described in claim 1 or 10, and wherein, described microprocessor is programmed to Expect that the noise of current signal is filtered to flowing through described transducer.

12. power supplys according to claim 3, wherein, including being arranged on described microprocessor and institute State the filter circuit between operational amplifier.

13. power supplys according to claim 3, wherein, described switching circuit is suitable to according to from described The variable voltage signal of operational amplifier output controls the frequency of described transducer, the increase of its medium frequency Corresponding with the reduction that driven by magnetron power and microwave export.

14. power supplys according to claim 1 and 2, wherein, described switching circuit is suitable to according to institute State IC input and out control the dutycycle of described transducer, the reduction of wherein said dutycycle and magnetic control The reduction that pipe driving voltage exports with microwave is corresponding.

15. power supplys according to claim 1 and 2, wherein, described switching circuit is suitable to according to institute The clock stating microprocessor carrys out timing.

16. power supplys according to claim 1 and 2, wherein, described switching circuit has oneself Agitator.

17. power supplys according to claim 1 and 2, wherein, described transducer is zero voltage switching Device.

18. power supplys according to claim 1 and 2, wherein, described transducer is zero current switching Device.