41results about How to "Suppress parasitic oscillation" patented technology

The invention relates to a control method which can be applied to an active-clamp flyback miniature photovoltaic grid-connected inverter device. The active-clamp flyback miniature photovoltaic grid-connected inverter device comprises a flyback converter and a power frequency polarity conversion circuit. In the device, a current reference is used for controlling a flyback primary-side current peak value so that the device can output a half-wave sinusoidal current, and the output voltage is clamped by a grid voltage. When the instantaneous power is lower, a constant frequency current discontinuous mode in combined with a variable frequency current critical continuous mode is adopted in the flyback control method. When the flyback converter works in a variable frequency current critical discontinuous mode, an auxiliary switching tube can be conducted for a period of time when the secondary-side current of the flyback converter reaches zero, the conduction time can be accurately controlled by a digital chip, thus realizing the leakage inductance energy feedback and the soft switch of a master switching tube under the condition of wide-range output voltages and different instantaneous powers and greatly improving the efficiency under the condition of full loads.

A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges using a substantially high index bonding elastomer or epoxy to a predetermined electromagnetic absorbing arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

The invention relates to the field of DC/DC conversion, and aims at providing a rectifier circuit for realizing the voltage clamp of a rectifier tube by using a double-power transformer. The rectifier circuit comprises two power transformers, four rectifier diodes, and two auxiliary capacitors, wherein two secondary windings of the power transformer have a center-tapped rectifying structure respectively. The rectifier circuit of the invention simplifies the winding structure of each transformer, and enhances the use ratio of a magnetic core window. On different occasions, primary windings of the two power transformers can adopt a serial or parallel connection structure flexibly. The rectifier circuit of the invention can effectively restrain the parasitic oscillation of voltages on the rectifier tube by aid of nondestructive capacitance energy-storage components without any active auxiliary devices; the production of the center-tapped secondary windings of the power transformer is relatively simple, and the connection between the transformers and the external electric components is reduced, which is helpful for improving power density. Therefore, the rectifier circuit is suitable for topological structures of various converters.

The invention relates to a method of suppressing the titanium gem laser amplifier parasiteic oscillation and equipment, the equipment characteristicis is that including a hull shape support which is used for installing the titanium gem crystal, on the lateral wall of the hull shape support has drop liquid hole and air hole for filling the liquid matching matter. The characteristic of the invention is that the liquid mathing matter is easy to collocate, and even contact with the side face of titanium jewel, without gas bubble, have no special request of the titanium gem crystal side face, most of all easy to replace, can not cause the damage to the crystal plane, the invention also has low cost, simple operate merit.

A film bulk acoustic wave resonator comprises a bottom electrode layer, a piezoelectric layer and a top electrode layer which are arranged on the upper portion of a substrate where an acoustic wave reflection structure is located, and the portion, corresponding to the boundary of the acoustic wave reflection structure, of the piezoelectric layer is subjected to depolarization treatment to form a depolarization part. The invention further discloses a manufacturing process of the film bulk acoustic resonator. The manufacturing process comprises the following steps: manufacturing the bottom electrode layer on the substrate on which the acoustic reflection structure is formed or to be formed so as to cover the acoustic reflection structure; manufacturing a piezoelectric layer on the bottom electrode layer; carrying out depolarization processing on the part, corresponding to the boundary of the sound wave reflection structure, of the piezoelectric layer to form a depolarization part; and manufacturing a top electrode layer on the piezoelectric layer. According to the film bulk acoustic resonator and the manufacturing process thereof, transverse waves can be prevented from taking away energy from a resonance region at the upper part of the cavity of the resonator, so that the mechanical vibration strength of the resonance region is ensured, parasitic oscillation is inhibited, and theQ value of the resonator is improved.

Disclosed is a time-domain doublet pulse pumping method for restraining parasitic oscillation of a Ti sapphire multipass amplifier. The properties of time-domain doublet pumping pulse are utilized, time delay of seed light is adjusted and single-pass time interval of the multipass amplifier is adjusted to amplify 800-nanometer seed light to enable crosswise transmission gain of a Ti sapphire crystal to be kept in a low level in the process of amplifying, the parasitic oscillation of the Ti sapphire is effectively restrained, and amplifying efficiency of the seed light is improved. The time-domain doublet pulse pumping method for restraining the parasitic oscillation of the Ti sapphire multipass amplifier has the advantages of being convenient to adjust, simple, high-efficient and strong in practicality.

The invention discloses a manufacturing process of an acoustic resonator and the acoustic resonator. The acoustic resonator comprises a substrate, an acoustic mirror and a resonance film layer composed of a bottom electrode layer, a piezoelectric layer and a top electrode layer. An area where the resonance film layer and the acoustic mirror are overlapped in the thickness direction of the substrate is a projection area, an amorphous state part is arranged in the resonance film layer, one side of the amorphous state part is located in the projection area or coincides with the boundary of the projection area, and the other side of the amorphous state part is located outside the projection area. In a preferred embodiment, the acoustic mirror includes a cavity or Bragg reflection layer. The amorphous state part can greatly suppress parasitic oscillation of the resonator due to outward connection of the top electrode layer. The electrode layer can be directly wired in the area where the amorphous state part is located, parasitic and resonant interference generated by the bottom electrode layer, the top electrode layer and the piezoelectric layer outside the effective resonant area is avoided, and the process cost and wiring design difficulty are reduced.

The invention discloses a zero-voltage transmission half bridgeless Boost PFC converter. According to the invention, only by adding a rapid recovery diode D7 can an RCD clamp network be replaced; parasitic oscillation during cutting off of quasi zero current of an auxiliary switch tube is inhibited; the topology of the converter is simplified; and when the auxiliary switch tube is turned off, exciting current will be introduced into a parasitic capacitor, and is fully used by a circuit, so the overall efficiency of the converter is improved. In addition, through the provided converter, natural turning on and turning off of a zero voltage switch and a boost diode of a main switch tube are achieved; natural switching on and off of each connected diode in the circuit is also achieved; technical problems of complex topology, quite high cost and quite low overall efficiency of a converter in the prior art are solved; and the provided converter can be well popularized in actual application.

The invention discloses a xenon lamp-pumped liquid cooling laminated repetition frequency sheet amplifier. The xenon lamp-pumped liquid cooling laminated repetition frequency sheet amplifier comprisesa lamp box assembly, a sheet frame assembly, a sheet cavity assembly and an end mirror assembly, and is characterized in that the included angle theta of the sheet frame assembly and the light transmission direction is 45 degrees for installation; the sheet frame assembly is installed inside the sheet cavity assembly from top to bottom; the lower bottom surface of the sheet frame is overlapped with the upper surface of the lower base plate of the sheet cavity; the lamp box assembly is installed on the left and right sides of the sheet cavity assembly in virtue of screw dislocation; and the end mirror assembly is centrally dislocated along the light transmission direction and is installed on the front and rear sides of the sheet cavity assembly in virtue of screws. The spontaneous radiation of the amplifier is reduced effectively by using end mirror inclination swing, xenon lamp liquid cooling, gain medium laminated liquid guide uniform cooling and sheet box air-cool clean control, theparasitic oscillation is inhibited, the energy storage efficiency and heat management are improved, and the repetition frequency sheet amplifier has the characteristics of high efficiency, high repletion frequency, low cost, high energy, high gain uniformity and stable operation.

A plurality of semiconductor elements connected in parallel with one another include a plurality of first semiconductor elements and a plurality of second semiconductor elements. A drive circuit to provide a gate signal to each of the plurality of semiconductor elements EL includes a main circuit and a plurality of inserted circuits including a first inserted circuit and a second inserted circuit. The first inserted circuit is inserted between the main circuit and the plurality of first semiconductor dements. The second inserted circuit is inserted between the main circuit and the plurality of second semiconductor elements. Each of the first inserted circuit and the second inserted circuit includes a first diode having a forward direction toward the main circuit and a second diode connected in anti-parallel with the first diode.

The invention discloses a high frequency oscillator inhibiting parasitic oscillations; the high frequency oscillator comprises a DC power supply circuit, an oscillation generation circuit and a parasitic oscillation inhibition circuit; the DC power supply circuit comprises a DC voltage source V1, a high frequency choke coil L2, a first filter capacitor C11, a second filter capacitor C22, a first bias resistor R1, a second bias resistor R2 and a first bias capacitor C0; the oscillation generation circuit comprises a first transistor Q1, a first resonant capacitor C1, a second resonant capacitor C2, a third resonant capacitor C3, a fourth adjustable resonant capacitor C4, a first feedback resistor R3 and a first resonance inductor L1; the parasitic oscillation inhibition circuit comprises a first coupling capacitor C5, a second transistor Q2, a first current-limiting resistor R4, a first frequency selection capacitor C6, a second frequency selection capacitor C7, and a first frequency selection inductor L3; the high frequency oscillator can stably form high frequency sine waves, and can effectively inhibit parasitic oscillations.

The invention discloses a composite wall surface sealed tube cavity used for a side surface pumped alkali metal vapor laser. The composite wall surface sealed tube cavity is characterized by comprising an alkali metal vapor sealed tube cavity side wall and end windows positioned at the two ends of the alkali metal vapor sealed tube cavity side wall; a roughening region, which is used for performing roughening processing, is arranged on the inner wall surface of the alkali metal vapor sealed tube cavity side wall; the outer wall surface of the alkali metal vapor sealed tube cavity side wall is coated with high-reflective films with corresponding pumping wavelengths to form a high-reflective film region; the high-reflective films are corresponding to the roughening region; and a non-film-coated region between adjacent high-reflective films is used as an incident region of semiconductor pumped beams. By adoption of the composite wall surface sealed tube cavity, parasitic oscillation in the vapor cavity can be effectively suppressed, pumped energy loss and corresponding thermal load related therewith can be effectively reduced, and output power of a DPAL system can be improved.

A power module including a half bridge circuit having first and second switching elements respectively included in an upper arm and a lower arm thereof, and upper and lower arm drive circuits which respectively drive the first and second switching elements. The power module includes a first ground terminal on a ground side of the second switching element, a second ground terminal connected, via a first ground wiring, to the first ground terminal, a third ground terminal connected, via a second ground wiring including a dumping resistor, to the first ground terminal, a current detection circuit detecting a current flowing through the second switching element, and a control ground switching circuit which performs switching according to a value of the current detected by the current detection circuit, so as to connect a ground terminal of the lower arm drive circuit to the second or third ground terminal.

An oscillator includes a resonator configured to resonate an electromagnetic wave in a resonant axis direction and a capacitance unit electrically connected in parallel to the resonator. The resonator includes a negative resistor, a first conductive layer, and a second conductive layer, where the negative resistor has a gain to the electromagnetic wave and is disposed between and in contact with the first conductive layer and the second conductive layer. At a resonant frequency f_LC generated by an inductance Ls which the wiring configured to electrically connect the capacitance unit to the resonator and the capacitance unit constitute, and an inner capacitance Cwg of the resonator, a conductance including the inductance Ls, a resistance component Rs of the wiring and the capacitance unit, and a capacitance C of the capacitance unit is equal to or higher than an absolute value Gwg of negative conductance of the negative resistor.

The invention relates to the field of DC/DC conversion, and aims at providing a low-EMI asymmetrical centre tap rectification circuit. The primary side of the low-EMI asymmetrical centre tap rectification circuit is a half-bridge LLC topology, the back stage is a centre tap rectification circuit; the windings at the primary and secondary sides of a power transformer adopt a staggered wound winding structure; the same-name end of the transformer winding is defined as a positive end and the other end is defined as a negative end; the negative pole of a first rectification diode and a negative end of a second secondary-side winding are connected with the positive end of an output filtering capacitor; the positive pole of a second rectification diode and the negative end of a first secondary-side winding is connected with the negative end of the output filtering capacitor; the positive pole of the first rectification diode is connected with the positive end of the first secondary-side winding; and the negative pole of the second rectification diode is connected with the positive end of the second secondary-side winding. The low-EMI asymmetrical centre tap rectification circuit reduces common-mode current and interference caused by the common-mode current, removes or relieves a current extraction effect from the common-mode current between the primary and secondary sides of the transformer to the current of an excitation inductor, reduces dead time of a bridge wall switch tube and improves the conversion efficiency of a converter.