Transistor generator for resonant loads

FIELD: electricity.

SUBSTANCE: transistor generator for resonant loads contains half-bridge inverter based on IGBT transistors controlled as per standard scheme by driver of the half-bridge inverter with internal generator and external time-setting RC-circuit; generator contains output transformer, optron command device and current transformer, which data output is connected to capacitor, through which RC-circuit is connected in parallel to capacitor of external time-setting RC-circuit of the driver; current transformer is equipped with two primary windings, at that the main winding is connected to the first circuit of output transformer secondary winding in-series with resonant load, while auxiliary winding through auxiliary capacitor and RF choke is connected to the second circuit of output transformer secondary winding.

EFFECT: improving operational reliability to alternating high-Q load of piezoceramic radiator type at high values of equivalent process duty.

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The invention relates to the field of transformative technology and can be used in various technological processes with the use of ultrasonic vibrations.

Known transistor generators, made on the basis of half-bridge or bridge inverters [Moin B.C. "Stable transistor inverters. - Meters, Energy, 1986, - 136 C.; RF Patent №2086070 "Ultrasonic transistor generator", MKI 5 NM 7/537, B. I. No. 21, 1997]. They are quite simple in circuit design, but have some significant drawbacks that prevent their widespread use in ultrasonic processes, namely:

a strong dependence of the frequency on the supply voltage;

- difficulties in the implementation of the broadband system-locked loop.

Also known transistor generator [RF Patent №2260899 "Transistor generator for resonant loads", IPC 7 NW 5/12, NM 7/537, B. I. No. 26, 2005], is taken as a prototype. It contains half-bridge transistor inverter with an output transformer IGBT controlled included in the model scheme of the half-bridge driver with integrated master oscillator, made by NOSFET technology with external setting RC-circuit. The use of modern transistors and the latest developments in micro circuitry half-bridge drivers Information material PD-91800 company International Rectifier technical characteristics of the driver half-bridge IR2153Z] possible to ensure high reliability of operation of half-bridge inverter due to the formation of the optimal modes control transistors, and the use of opto-command device enabled to achieve high noise immunity and reliability in the control of the generator. Use for phase-locked loop frequency current transformer and an internal signal of the driver provided a simple and reliable system for effective operation of the oscillator at the resonant load.

The main disadvantage of using this type of generators to work at the resonant load type piezoelectric emitters is significant (sometimes more than an order of magnitude) increase of the load active power elements of the generator in modes that are close to idling. Especially when the powerful generators on high-q piezoelectric emitters in technological processes, designed for heavy loads, which significantly reduces the reliability of the transistor generator

The technical result of the invention is to improve the reliability of the transistor generator for sharply varying high-q load type piezoelectric oscillator at higher values equivalent to the process load.

This technical result is achieved in that the transistor generator for resonant loads, containing half-bridge inverter IGBT t is ansestor, managed included in the model scheme of the half-bridge driver with internal oscillator and external timing RC circuit made by NOSFET technology, with an output transformer, opto-transistor and the current transformer, the information output of which is connected to the condenser via an RC-circuit connected in parallel with the capacitor external timing RC circuit included in the circuit of the secondary winding of the output transformer in series with the resonant load, according to the present invention is further provided with two capacitors, two resistors, a secondary winding of the current transformer, the key of alternating current, a comparator, and a rectifier, and an additional secondary winding of the current transformer is connected to the first capacitor and the input of the rectifier, the output of which is connected to the first input of the comparator, the second input is connected with a source of reference voltage, and the output connected to the control input of the key AC connecting additional secondary winding of the current transformer to the first additional resistor and connected in series through a second capacitor and a second resistor to the capacitor timing chain driver.

Fig.1 shows a schematic diagram of a device.

The scheme consists of a half-bridge tra is sistemnogo inverter 1 with the control driver included in the model scheme, with the output transformer 2 in the diagonal half-bridge. Managing the driver has a built-in oscillator with external timing RC circuit 3-4. In parallel to the capacitor 4 timing RC circuit via an RC-link 5-6 connected capacitor 7 connected to the information winding of the current transformer 8, the primary winding which connects the output of the secondary winding of the output transformer 2 and the first output of the resonant load in the form of a piezoelectric oscillator 11. The other terminal of the secondary winding of the output transformer 2 is connected to the second output of the resonant load 11. Additional secondary information) winding of the current transformer 9 parallel to the first additional capacitor 10 is connected to the input of the rectifier 13 and through the key AC 14 to the first additional resistor 15 and through the serial chain of the second additional resistor 17 and the second additional capacitor 16 to the condenser 4 setting RC - circuit driver. The output of rectifier 13 is connected to the first input of the comparator 18, the second input is connected to the reference voltage, and the output connected to the control input of the key AC 14.

The device operates as follows.

In the initial state power voltage to which Emmy power inverter, but the inverter is not working because the opto-command device 12 is not included. When applying a control signal to opto-command device latest offers, providing the resolution of the normal operation of the driver. Thus, opto-command device controls the operation of the driver.

When operating at the resonant load, which is considered an ultrasonic piezoelectric emitter 11, the current flowing in the secondary winding of the output transformer 2, depending on the quality factor of the load is more or less closer to a sine wave. The main task of the generator is running on a piezoelectric emitter, is to maintain the maximum amplitude of acoustic oscillations of the radiator (which corresponds to the mode of operation, called mechanical resonance) under different conditions of technological process (for various technological applications). With a relatively simple equivalent circuits of the resonant load, approaching in a resonant modes to the simplest resonant circuits, the preferred control system frequency is the phase. In its standard version, this system is quite complicated in execution, the inertia due to the filters used, requires multiple sensors, because the ku must ensure that certain phase relation between the output current and the output voltage, must contain blocks converting the compared signals and blocks the generation of control signals. A known system (prototype), keeping in this sense, all their positive qualities, maintains the electrical resonance of the acoustic system (piezoelectric oscillator), and not mechanical, because as one of the phase signals is used the total current of the speakers representing the sum of the mechanical and electrical branches of the equivalent circuit of the piezoelectric oscillator [Ultrasonic transducers, Ed. Achikochi. - M.: MIR, 1972. - 424 S.].

The proposed system phase frequency control of the generator does not have the mentioned disadvantages. Upon the receipt of the current signal to the main primary winding of the current transformer 8 through a counter included additional primary winding passes a current corresponding to the electric component of the total current due to the inclusion of additional capacitor 10, the capacity of which corresponds to that of the capacitance of the used piezoelectric ceramics. As a result, information winding of the current transformer 8 to the condenser 7 is a selection of the information signal corresponding to the first harmonic of the current of a mechanical branch speakers. This information signal cher the C RC-circuit 5-6 on the capacitor 4 setting RC - a driver circuit which compares the phase and the conversion phase mismatch of information signals corresponding to the first harmonic of the current of a mechanical branch speaker system (resonant load) and output voltage.

Because piezoelectric emitter 11, which is the burden of the proposed generator, characterized by the equivalent circuit of the series resonant circuit [Ultrasonic transducers, Ed. Achikochi. - M.: MIR, 1972. - 424 S.], whose active resistance are placed in series resistance losses and the resistance of the technological burden, it is obvious that in the coherent mode, when working at frequencies close to resonance, the equivalent resistance of the emitter as the output load generator transformer will vary within very wide limits, depending on the value of the process load. That is, in the absence of technological load (idle mode) is equivalent to the resistance of the emitter is small and the quality is great, but with significant processing load (for example, when the operation of the ultrasonic scalpel on the bone or when cleaning in a liquid medium large active surface of the ultrasonic tool) is equivalent to the resistance of islocated who can grow more than an order of magnitude, and the figure of merit accordingly much diminished. This leads to a significant reduction of the current flowing through the piezoelectric emitter, and, accordingly, reduction of the primary process variable - amplitude oscillations of the working end of the ultrasonic transducer. To compensate for this phenomenon is proposed to use an additional high-frequency choke 9. On the one hand, providing an electrical resonance circuit formed by the inductor 9 and the self-capacitance of the piezoelectric transducer generates a voltage at the emitter is close to sinusoidal, and on the other hand, provides the sound system and generator mode, close to the source of current, because the increase of the equivalent load factor of the circuit increases and the voltage at the emitter is increased, to some extent, keeping the current flowing through the emitter current. If there is a clear increase in the influence of the electric component of the total current with the increase of the equivalent load resistance. The obvious necessity of adaptation of the system mode-locked loop to variable over a wide range of the load parameters. The proposed scheme generator and provides this kind of adaptation due to the compensation of the electrical component in the full current of the emitter and suitable the change in the current signal, coming from the current transformer 8 when changing the q-factor of the load.

Thus, the proposed transistor generator for resonant loads is very simple in execution, allows you to use the most modern element base, which in combination provides high reliability. In addition, the use of the proposed system phase-locked loop frequency due to the direct conversion of phase shift in the frequency change allows to minimize the duration of transient processes, on the one hand, and to improve the acoustic efficiency of the transistor of the generator when operating at the resonant load type piezoelectric oscillator at higher values equivalent to the process load.

The proposed scheme has the following advantages over known:

to use the default schema transistor inverter on modern element base and the control driver included in the model scheme, provides circuit simplicity and high reliability of the generator as a whole, and the application of the proposed extremely simple system phase-locked loop allows you to maintain high reliability even when giving him new important functions;

the internal signal generator is a (with capacitor timing RC circuit driver), as one of the compared phase, provides the possibility of direct conversion of the phase shift in the frequency change of the output signal generator;

- finally, the application of the proposed system allows to adapt the generator to the changing conditions of the q-factor of the resonant load.

Transistor generator for resonant loads, containing half-bridge inverter IGBT controlled included in the model scheme of the half-bridge driver with internal oscillator and external timing RC circuit made by NOSFET technology, with an output transformer, opto-transistor and the current transformer, the information output of which is connected to the condenser via an RC-circuit connected in parallel with the capacitor external timing RC circuit included in the circuit of the secondary winding of the output transformer in series with the resonant load, characterized in that it further comprises: two capacitor, two resistors, the secondary winding of the current transformer, the key AC the comparator and the rectifier, and an additional secondary winding of the current transformer is connected to the first capacitor and the input of the rectifier, the output of which is connected to the first input of the comparator, the second input is connected with the reference voltage is Oia, and the output connected to the control input of the key AC connecting additional secondary winding of the current transformer to the first resistor and connected in series through a second capacitor and a second resistor to the capacitor timing chain driver.