37results about How to "Reduce waveform distortion rate" patented technology

The invention discloses a VSVPWM (Virtual Space Vector Pulse Width Modulation)-based three-level inverter neutral point potential compensation balance control strategy. A virtual median vector is introduced on the basis of the conventional SVPWM, the current which flows by a neutral point in each sampling period can be zero through recombination of a small vector and the median vector. The invention provides the VSVPWM-based neutral point potential accurate compensation control strategy. According to the method, a voltage adjustment coefficient is introduced according to detected neutral point potential deviation, three-phase output current and direct current side neutral point current direction to set different adjustment coefficients for different small vectors so as to increase the control capacity of corresponding positive or negative small vector to the neutral point current and reduce the fluctuation of the neutral point potential.

The invention discloses a power cable field partial discharge signal noise reduction method. The method comprises the steps that S1 a field power cable partial discharge signal is collected, and digital processing is carried out to form the time domain signal f (t) of the field partial discharge signal; S2 the time domain signal f (t) is converted to a corresponding frequency domain function F (omega) through fast Fourier transform, and mathematical processing is carried out on the frequency domain function F (omega) to acquire a fast Fourier power spectrum described in the description; S3 anAGFCM algorithm is used to classify noisy signal power spectrum data into two categories; S4 narrow band interference peak is positioned; the positioned narrow band interference peak is compressed; inverse fast Fourier transform is carried out on P (omega) after narrow band interference peak filtering to acquire a narrow band noise filtered signal g (t); and S5 wavelet transform analysis is carried out on g (t); mother wavelet is selected; a threshold is determined; white noise is filtered out to acquire a final denoised signal. According to the invention, periodic narrow-band noise can be suppressed; the waveform distortion rate is reduced; and the signal-to-noise ratio of the denoising result is improved.

The invention discloses a coreless brushless direct current motor, which comprises a bearing, a stator, a rotor and a rotor position sensor assembly, wherein the stator coreless winding is a concentric multilayer winding; a winding lead is welded by adopting an adapter plate assembly; the multi-pole annular magnetic pole is P, the HALBACH structure is adopted for overall multi-pole magnetization,and it is guaranteed that the air gap flux density wave of the winding coupling part is in a sine form; the motor end cover, the casing, the stator, the rotor, the bearing and the Hall positioning circle center are coaxially arranged. The product provided by the invention is simple in structure, convenient to assemble, compact in structure, small in size, small in size, light in weight, small in loss, high in efficiency, high in power and torque density, high in counter potential sine, low in waveform distortion rate, low in operation noise and vibration, small in torque ripple and high in reliability. The coreless brushless motor has the advantages of simple structure, high dynamic response speed, stable control operation, high control precision, high reliability and the like.

The invention discloses a pulse-width modulation (PWM) inverted power supply system and a PWM inverted power supply algorithm based on a fuzzy predictive control technology. The input is direct current (DC) voltage, and the input passes through a DC booster circuit, is subjected to ripple wave removal through a filtering circuit and passes through a DC / alternating current (AC) inversion circuit; the output is high-voltage AC, an AC voltage detection feedback circuit, an overcurrent detection feedback circuit, a DC detection feedback circuit, a DC voltage detection feedback circuit and other protection circuits are arranged in the circuit, when overcurrent and overvoltage are detected, a control chip obtains a reasonable dead-zone predictive control scheme through an algorithm according to data which is acquired in real time, the PWM driving pulse waveform is changed, and the working reliability of a switching device is effectively guaranteed; meanwhile, the conversion efficiency of a PWM inverter system is high, and the distortion rate of output waveform is reduced. The invention is applicable to fields of switching power supply inverters, solar inverted power supplies, small wind driven generator inverted power supplies and the like.

The invention relates to a generator, in particular to a high-power harmonic wave excitation generator which solves the problem of higher voltage waveform aberration rate of a triple harmonic wave winding and a primary winding of the existing harmonic wave excitation generator. The high-power harmonic wave excitation generator comprises a stator, a primary winding and a triple harmonic wave winding embedded in a stator groove, wherein the primary winding is a double-layer wave winding; the triple harmonic wave winding is a single-layer concentric type winding with different turns, i.e., in eight grooves under each pole pair of the triple harmonic wave winding, no conductors are arranged in a third groove and a seventh groove; the ratio of the number of turns of the single-layer concentriccoils in the first and fifth grooves to the number of turns of the single-layer concentric coils in the second, fourth, sixth and eighth grooves is 1:0.707 which is rounded; and the primary winding adopts a short-range winding. The waveform aberration rate of the triple harmonic wave winding can be reduced to 15 percent and the waveform aberration rate of the primary winding can be reduced by 4.8percent. The excitation generator is applicable to mining electric drive dumper lorries and also can be used in other fields of railway, generating plant, industrial and mining, and the like.

This invention relates to a continuous rotating type ac electric motor, particularly three phase, low wave form distortion, high efficiency ac electric motor being composed of a rotor and a stator. The stator comprises: a seat, a stator core and stator winding each of the three phase stator winding occupies one layer of stator core channel. On the cross-section of the stator core, the corresponding end points of three-layer winding are of 120 deg. intervals. This invention breaks-through prior art mode of single layer or double layers of stator winding of three-phase motor, so it can eliminating distortion wave form of three phase electric motor, the distortion rate is less than 2%. The efficiency of electric generation is greater than 95%, while the efficiency of electric motor is greater than 90%.

The invention discloses a high-power non-partial discharge variable-frequency power source used for high-voltage tests and a parallel-operation resonant testing device thereof. The high-power non-partial discharge variable-frequency power source comprises a signal generator, a digital potentiometer, a preceding-stage power amplifier circuit, a bridge-type power amplifier circuit, a rectifier filter circuit, a pre-closing circuit and a fast overcurrent protecting circuit, wherein the signal generator is used for generating a standard sine-wave signal to carry out frequency and voltage regulation through the digital potentiometer and outputting the signal to directly push the preceding-stage power amplifier circuit, the preceding-stage power amplifier circuit is divided into two paths of output, one path of output is used for generating a synchronous power source with same test frequency so as to be fed to a local discharge instrument, and the other path of output is used for pushing thebridge-type power amplifier circuit; the pre-closing circuit is electrically connected to the rectifier filter circuit and the bridge-type power amplifier circuit; the bridge-type power amplifier circuit consists of four high power transistors to form four bridge arms, and each bridge arm mainly consists of more than one thousand transistors in parallel. A step-by-step amplification principle isadopted, original micro power signals are amplified repeatedly to realize high-power output, and the testing requirement is met.

The invention discloses a coreless brushless direct current motor with a locking device. The motor comprises a motor main body and a locking device. An output end is arranged at the front part of themotor main body. A locking device is arranged at the rear part of the motor main body. The motor main body realizes output of torque, rotating speed and power function indexes. The motor main body iscomposed of a front end cover, a stator armature, a casing, a rotor and a rear end cover. The front end cover is arranged at the front end of the casing, the rear end cover is arranged at the rear endof the casing, the rotor is installed in the middle of the casing, and the stator armature is arranged outside the rotor in a matching manner. By optimizing the sizes of parts of the motor, the rotorposition sensor and the locking device and through the multifunctional design of the parts, the size of the motor is fully utilized, the axial and radial sizes of the motor are reduced, and product miniaturization and high power density are achieved.

The invention aims to provide a low-spurious sinusoidal signal generator based on a multi-point compensation scheme. The low-spurious sinusoidal signal generator based on the multi-point compensation scheme comprises a main D / A conversion module and a high-speed D / A conversion module; the main D / A conversion module is a low-speed D / A converter having high effective bit, and is responsible for outputting sinusoidal waveform; the high-speed D / A conversion module generates a harmonic counteraction signal zeta(t), and is used for counteracting the harmonic component in the sinusoidal waveform generated by the main D / A conversion module; after being subjected to subtraction through an addition and subtraction operation circuit, the two signals are output; and thus, sinusoidal voltage output after harmonic counteraction is finally obtained. The low-spurious sinusoidal signal generator overcomes the disadvantage that both the effective bit and the conversion speed cannot be obtained at the same time in the prior art; when the harmonic component in the sinusoidal wave generated by the sinusoidal signal generator is effectively reduced, the A / D conversion speed of the sinusoidal signal generator can be ensured; and thus, sinusoidal wave signals having relatively low waveform deviation rate can be obtained.

The invention discloses an upper and lower bus current cooperative control method for parallel operation of current source rectifiers, and the method comprises the steps: carrying out the sampling andfiltering of the upper and lower bus currents of two rectifiers, and transmitting an error between the output currents of buses of the two rectifiers and a reference current to a proportional-integral controller for adjustment; and obtaining a delay angle required by modulation. Besides, the difference value of the lower bus current is sent to a proportional integral controller to calculate and obtain a bypass pulse width control parameter, and the two are combined to flexibly adjust the output current of the upper and lower buses and realize the purpose of cooperative control of the upper and lower bus currents when the rectifiers are connected in parallel.

The invention discloses a double-random SVPWM modulated SVG double-sequence synchronous control method, which comprises the following steps: 1. Detecting load current, SVG output current, DC side capacitance voltage and grid voltage; 2, compensate that positive sequence component and the negative sequence component respectively by adopting the positive and negative two-sequence control strategy; 3, acquiring a voltage command signal; 4, that drive signal of the bridge circuit is obtained by the double random SVPWM control method, the power switch transistor is controlled, and the reactive power and the negative sequence current component are compensated. So that that structure of the invention is clear, not only can the reactive current component and the negative sequence current componentcaused by load unbalance be compensated accurately, At that same time, the harmonic characteristic of SVG power bridge circuit is consider, and the harmonic peak of output current and line voltage issuppressed by using the double random SVPWM modulation method, which can reduce the harmonic pollution of SVG to the power system when the SVG is in grid-connected operation.

The invention provides a single-phase grid-connected photovoltaic power generation system output power smooth control device and a control method. The device comprises a grid-connected photovoltaic power generation system which consists of a photovoltaic power source, a Boost convertor, a direct current filter capacitor, a storage battery, a first bidirectional direct current convertor, a supercapacitor, a second bidirectional direct current convertor and an inverter, and also comprises a first control device and a second control device which respectively control the charging and discharging of the storage battery and the supercapacitor; the storage battery adopts a double-closed-loop control mode of power external loop and current internal loop; the supercapacitor adopts a double-closed-loop control mode of voltage external loop and current internal loop; the instantaneous power can be rapidly balanced, harmonic waves can be inhibited, the waveform deviation factor of grid-connected current can be reduced, and the grid-connected electric energy quality of a photovoltaic system can be improved.

The invention discloses a surface-mounted permanent magnet voltage transformation frequency converter based on a magnetic field modulation principle and a design method, and the method comprises the following steps: additionally arranging a rotating magnetic field adjusting ring between an inner stator iron core and an outer stator iron core, modulating the rotating magnetomotive force generated by an inner stator winding of p antipodes into a rotating magnetic field of np antipodes through the rotating magnetic field adjusting ring, according to the transformer and the design method thereof, the inner stator winding and the outer stator winding correspond to np antipodes of the outer stator winding, the rotating magnetomotive force generated by the inner stator winding and the modulated three-phase rotating magnetic field rotate at the synchronous rotating speed, and the modulated rotating magnetic field induces n-frequency-doubled symmetrical three-phase alternating-current voltage in the outer stator winding. And the system has the characteristics of high economical efficiency, high operation reliability and excellent performance.

The invention provides a control method of a heat pump system. The control method comprises a PV / T system, a heating system, a power supply system and a control system, wherein the PV / T system comprises a PV collector, a compressor, a condenser, a reservoir, a drying filter, an expansion valve, a heat storage water storage tank, a water escape valve and a pressure protector. According to the novelcontrollable phase-change heat storage material provided by the invention, the heat release process is controllable, small heat loss in storage, controllable in phase change temperature, high in latent heat storage capacity, non-toxic, non-corrosive, and harmless to the environment and stable in chemical and thermal properties.

The invention provides a power generator which comprises a stator and a rotor. The stator comprises a stator iron core and a stator winding. Multiple stator slots which are uniformly distributed and obliquely arranged are formed in the inner ring of the stator iron core. The stator winding comprises a first layer winding, a second layer winding, a third layer winding and a fourth layer winding which are arranged in the stator slots in turn in a penetrating way. The first layer winding and the second layer winding form a first set of three-phase windings. The third layer winding and the fourthlayer winding form a second set of three-phase windings. The slot numbers of the initial stator slots of the first set of three-phase windings and the second set of three-phase windings differ by 30 degrees of electric angle. Two sets of three-phase windings are utilized to form six-phase stator windings, and the power generator can continue to operate under load shedding when one or more phases of the power generator are out of order. Meanwhile, the stator slots are obliquely arranged to weaken the influence of harmonic electromotive force so as to reduce the waveform distortion rate of the no-load output voltage of the permanent magnet synchronous generator.

The invention discloses a built-in permanent magnet variable frequency transformer based on a magnetic field modulation principle and a design method. The method comprises the following steps: additionally arranging a rotary magnetic field adjusting ring between an inner stator iron core and an outer stator iron core, arranging a built-in permanent magnet in the rotary magnetic field adjusting ring, and arranging a salient pole magnetic field adjusting block on the outer wall of the rotary magnetic field adjusting ring; modulating the rotating magnetomotive force generated by the inner stator windings of p pole pair into a rotating magnetic field of np pole pair by using the rotary magnetic field adjusting ring, enabling the rotating magnetic field to correspond to the np pole pair of an outer stator winding, and enabling the rotating magnetomotive force generated by the inner stator winding and the modulated three-phase rotating magnetic field to rotate at a synchronous rotating speed; and making the modulated rotating magnetic field to induce n-frequency-doubled symmetrical three-phase alternating-current voltage in the outer stator winding. According to the invention, by means of the built-in permanent magnet variable frequency transformer and the design method, electric energy frequency conversion can be achieved, and the built-in permanent magnet variable frequency transformer has the advantages of being high in economical efficiency, high in operation reliability and excellent in performance.

A permanent-magnet synchronous motor provided with a rotor structure having cage-type windings and a permanent magnet disposed on the inner peripheral side of the cage-type winding bar, wherein the permanent magnet is magnetized to provide a ratio theta / alpha of 0.54 through 0.67 between the peripheral-direction pitch angle theta of the permanent magnet's magnetic flux distribution and a magneticpole pitch angle alpha so as to ensure a required induced electromotive force with no increase in iron loss and to reduce a waveform distortion rate. Accordingly, a high-efficiency permanent-magnet synchronous motor can be provided due to an induced electromotive force having little distortion and a shape of nearly a sinusoidal wave.

The invention discloses a novel broadband high-voltage cascaded linear amplifier device. N linear amplifier modules are cascaded, and an independent direct-current power supply module is arranged in each linear amplifier module to supply power to the linear amplifier module, so that an input voltage signal can be amplified by N times, and high voltage can be output. Meanwhile, the linear optical coupling circuit is adopted to carry out signal transmission on the linear amplifier circuit, alternating current signals can be isolated, the insulation and anti-interference effects are achieved, cross-over distortion is greatly reduced, the waveform distortion rate is reduced, and meanwhile good linearity can be achieved through the linear amplifier circuit.

The invention relates to the field of mechanical and electrical technology, in particular to a single-phase voltage-regulating winding of a rare earth generator. The single-phase voltage-regulating winding of the rare earth generator adopts sine windings, the sine winding at one electrode is connected with a concentric winding with equal turns of each slot in series, and each electrode is respectively provided with a tap. The single-phase voltage-regulating winding is characterized in that a voltage-regulating winding is connected with the sine winding of each electrode at the maximum pitch in series, and each voltage-regulating winding is respectively provided with the tap, wherein, the number of coil turns of the voltage-regulating winding at one electrode is twice of that of the voltage-regulating winding at the other electrode. The single-phase voltage-regulating winding of the rare earth generator can improve the waveform, and the waveform distortion rate is less than 5 percent.

The invention discloses a novel axial coreless motor rotor structure and a heat dissipation method thereof. The structure comprises a plurality of permanent magnets annularly distributed on back iron along the radial direction, an air gap is arranged between two adjacent permanent magnets, a U-shaped iron pole is inserted in the air gap between every two adjacent permanent magnets, and air slots formed by the U-shaped parts of all the U-shaped iron poles face the back iron. The U-shaped iron poles are filled between every two adjacent permanent magnets in the rotor disc of the motor to improve the air gap flux density waveform of the axial coreless motor, so that the distortion rate of the air gap flux density waveform of the motor is reduced, the waveform of counter electromotive force of the motor is also improved, and the distortion rate is reduced. Meanwhile, the composite phase-change material is filled in the air slots added with the U-shaped iron poles, so heat generated by the motor rotor can be absorbed, the temperature of the motor rotor is reduced, and the demagnetization risk of the permanent magnets is reduced.

The invention discloses a radial magnetic pole damping cage structure of a generator rotor, which comprises two damping rings arranged at the two ends of a rotor respectively and a plurality of damping guide bars penetrating through a rotor core and electrically connected with the two damping rings, and the rotor comprises the rotor core, a rotor magnetic pole and a plurality of damping holes formed in the rotor magnetic pole. The damping holes are straight groove damping holes with the central axes parallel to the axis of the rotor iron core, the damping holes in the rotor magnetic poles are asymmetrically arranged at intervals, the distribution circle radiuses of all the damping holes are equal, the damping holes in the adjacent rotor magnetic poles are symmetrically arranged, and the same rotor magnetic pole has at least two sizes of damping hole pitches. According to the radial magnetic pole damping cage structure of the generator rotor, the amplitude of current harmonic waves in the damping winding can be effectively suppressed, the voltage waveform distortion rate is reduced, high-quality electric energy is obtained, and electromagnetic noise generated by the harmonic waves is weakened.

The invention relates to the field of electrical equipment and electrical engineering, in particular to a double-integral sliding mode controller based on carrier waves. The controller comprises: a comparison module, which is used for comparing the output voltage of a class-D amplifier with a time-varying reference signal to obtain an error signal; a PI control module, which is used for performing PI control on the error signal to obtain PI control output; a modulation signal generation module, which is used for generating a modulation signal, wherein the modulation signal is obtained by subtracting a transformed capacitance current signal on the basis of PI control output; and a pulse width modulation module, which is used for comparing the modulation signal with the triangular carrier generating a grid signal to obtain a driving signal of the class-D amplifier. According to the invention, the gain of an additional pole in a loop is added in a double-integral term, so that the waveform distortion rate of the class-D amplifier is reduced, and the dynamic response of a system is effectively improved.

The invention discloses a high-efficiency and wide-range programmable inverter power supply device and a control method thereof. Among them, the device includes a main circuit unit, the input end of which is connected to the mains, and the mains is converted into a DC signal by a filter, a rectifier and an inverter in turn to supply power to the load; the rectifier and the inverter are respectively connected to the programmable control unit; The programmable control unit is configured to preset the effective value of the voltage, and make a difference between it and the effective value of the voltage sampling feedback to obtain the voltage error; adjust the voltage error through PI to generate a PI adjusted voltage amplitude signal; adjust the PI voltage The amplitude signal is multiplied by the sine wave signal generated by the phase-locked output voltage of the filter to obtain a sine modulation voltage signal; the sine modulation voltage signal is subtracted from the received voltage instantaneous feedback signal, and then adjusted by PI and pre-set Multiply the proportional coefficients to obtain the SPWM voltage pulse width signal; the SPWM voltage pulse width signal is used to drive the switching tube in the rectifier, and finally generate a voltage waveform with a preset amplitude and frequency.

The invention provides a control method for improving the commutation accuracy of brushless DC motors. The difference in the number of interrupts between two conduction sections is taken as a feedbackvalue of the input end of a PI controller, and PI control is carried out to make the difference in the number of interrupts follow a reference value. The compensation angle obtained through PI control on the difference in the number of interrupts changes according to the actual commutation state. Whether the current motor commutation is ahead or lags behind is determined according to the symmetryof the slopes on the two sides of the trapezoidal terminal voltage wave, and then, the phase compensation is adjusted, so as to improve the accuracy of commutation. On the basis of the original sensorless brushless DC motor control system, the cycles maintained on each of the two sides of the trapezoid wave of each phase of counter electromotive force are counted, and phase compensation is carried out according to the difference in the number of count points between the two sides. The control method does not need an additional hardware circuit, is simple, and can improve the accuracy of commutation, reduce the waveform distortion rate of the voltage and current of the motor and reduce the torque ripple.

The invention discloses a stator and rotor structure of a surface-mounted permanent magnet motor, which comprises a stator, a rotor, stator water holes, permanent magnets and permanent magnet auxiliary grooves. In order to output high torque and stably operate the motor, the structure adopts an inner rotor and outer stator mechanism, the inner rotor adopts a magnetic pole surface-mounted type, and the magnetic pole adopts two non-uniform permanent magnets, the inner side arc and the outer side arc are located on the same circle with the proportion of 6:5, auxiliary grooves are formed in magnetic poles, excitation windings are placed in inner stator winding grooves, and two round holes are formed in stator teeth to be connected with water pipes to facilitate heat dissipation of the motor. According to the invention, the asymmetric structure of the magnetic poles is used to reduce eddy current loss and optimize the air-gap flux density waveform, reduce magnetic leakage and enhance the sinusoidal property of the air-gap magnetic field; the permanent magnets are used for forming auxiliary slots to reduce cogging torque pulsation; and the purposes of reducing the waveform irregularity and controlling the temperature rise are achieved by using the water holes formed in the stator, so that the motor can operate more safely and stably.

A ring dispersal winding of a turbonator is connected into a double layer lap winding by a coil. One to three end coil sides of each pole-phase group and the corresponding coil side of the adjacent phase group mutually exchange the connection of coil ends, and consequently the electric phase angle is locally replaced. The coil is a ring coil and formed by continuously winding a whole line without a welding point in the middle. The winding can satisfy the actual requirement of an electric network on preventing harmonic wave pollution during the synchronization of a generator and meanwhile dramatically shortens the period of goods delivery, saves the equipment production cost and is very high in reliability.

The present invention is one RE permanent magnetic generator with permanent magnet rotor and consists of stator and rotor. The stator includes iron core, single-layer winding and seat; and the rotor has even number of tile-shaped magnet poles of RE permanent magnetic material distributed homogeneously. The stator winding has several subsidiary windings, each of which is connected serially to the main winding of each pole. The generator of the present invention has the advantages of both single-layer winding and double-layer winding and has output voltage waveform deformation rate lower than 2 % and voltage regulating rate lower than 3 %.

An automatic calibration device for an AC voltage divider, including an industrial computer system connected in sequence, a broadband high-stable power supply, an intermediate frequency step-up transformer, a standard broadband voltage divider, and the standard broadband voltage divider is used for parallel connection with the AC voltage divider to be tested . The industrial computer system is used to send control signals to control the frequency and amplitude of the output voltage of the broadband high-stable power supply according to the preset voltage detection point, to sample the voltage of the standard broadband voltage divider, and to adjust the standard broadband voltage divider by feedback automatic control The error between the voltage at the high-voltage end and the target set voltage, when the voltage at the high-voltage end of the standard broadband voltage divider reaches the preset voltage detection point, the boost will automatically stop; the intermediate frequency step-up transformer is used to boost the output voltage of the broadband high-stable power supply Then output to the standard broadband voltage divider and the AC voltage divider to be tested. The invention has stable output voltage, small waveform distortion rate, and small frequency deviation, which can avoid reading changes of resistive-capacitive voltage dividers caused by voltage quality problems. The entire detection and calibration process is fully automatic, and manual or mechanical voltage regulation can be avoided. Process operation error.

The invention discloses a current synergistic control method for the upper and lower busbar currents of current source rectifiers in parallel operation. The upper and lower busbar currents of two rectifiers are sampled and filtered, and then the error between the output current and the reference current of the upper busbars of the two rectifiers is sent to the The proportional integral controller is used for adjustment to obtain the delay angle required for modulation. In addition, the difference of the lower bus current is sent to the proportional integral controller to calculate the bypass pulse width control parameter. The combination of the two can flexibly adjust the output current of the upper and lower bus, and realize the coordinated control of the upper and lower bus currents when the rectifiers are connected in parallel. Purpose.

The invention discloses a waveform control system, comprising a Miller integrating circuit, a Schmidt circuit, a Schmidt trigger and a power supply VCC, wherein the output end of the Miller integrating circuit is connected with the Schmidt circuit, the output end of the Schmidt circuit is separately connected with the input end of the Schmidt trigger and the input end of a filter circuit, the output end of the Schmidt trigger is connected with the input end of the Miller integrating circuit, the power supply VCC separately supplies power to the Miller integrating circuit and the Schmidt trigger, and the output end of the filter circuit is connected with the output end Vo of the system. According to the waveform control system disclosed by the invention, a direct current power supply VCC is directly converted to a square wave signal, the amplitude value and frequency of the square wave signal at the output end can be changed by changing the size of the power supply VCC and the charge and discharge frequency of a capacitor C1, the secondary amplification is not required, high stability can be achieved, and the obtained waveform is low in distortion rate.