Showing papers on "Bridge circuit published in 2018"

A Gate Driver of SiC MOSFET for Suppressing the Negative Voltage Spikes in a Bridge Circuit

Abstract: SiC mosfet has low on-state resistance and can work on high switching frequency, high voltage, and some other tough conditions with less temperature drift, which could provide the significant improvement of power density in power converters. However, for the bridge circuit in an actual converter, high dv/dt during fast switching transient of one mosfet will amplify the negative influence of parasitic components and produce the significant negative voltage spikes on the complementary mosfet , which will threaten its safe operation. This paper proposes a new gate driver circuit for SiC mosfet to attenuate the negative voltage spikes in a bridge circuit. The proposed gate driver adopts a simple voltage dividing circuit to generate a negative gate-source voltage as traditional and a passive triggered transistor with a series-connected capacitor to suppress the negative voltage spikes, which could satisfy the stringent requirements of fast switching SiC mosfet s under the high dc voltage condition with low cost and less complexity. An analysis is presented in this paper based on the simulation and experimental results with the performance comparison evaluated.

Piezoelectric self-sensing actuator for active vibration control of motorized spindle based on adaptive signal separation

Abstract: The motorized spindle is the core component of CNC machine tools, and the vibration of it reduces the machining precision and service life of the machine tools. Owing to the fast response, large output force, and displacement of the piezoelectric stack, it is often used as the actuator in the active vibration control of the spindle. A piezoelectric self-sensing actuator (SSA) can reduce the cost of the active vibration control system and simplify the structure by eliminating the use of a sensor, because a SSA can have both actuating and sensing functions at the same time. The signal separation method of a SSA based on a bridge circuit is widely applied because of its simple principle and easy implementation. However, it is difficult to maintain dynamic balance of the circuit. Prior research has used adaptive algorithm to balance of the bridge circuit on the flexible beam dynamically, but those algorithms need no correlation between sensing and control voltage, which limit the applications of SSA in the vibration control of the rotor-bearing system. Here, the electromechanical coupling model of the piezoelectric stack is established, followed by establishment of the dynamic model of the spindle system. Next, a new adaptive signal separation method based on the bridge circuit is proposed, which can separate relative small sensing voltage from related mixed voltage adaptively. The experimental results show that when the self-sensing signal obtained from the proposed method is used as a displacement signal, the vibration of the motorized spindle can be suppressed effectively through a linear quadratic Gaussian (LQG) algorithm.

Novel Transformer-Less DAB Converters for the Regulated First-Stage of a Two-Stage 48 V VRM

Abstract: This paper proposes a new family of high power density Transformer-less Dual Active Bridge DC/DC converters. Each converter consists of a switched-capacitor voltage divider (SCVD) derived Switched-Capacitor Bridge circuit on the one side, a standard Half-Bridge or a Full-Bridge circuit on the other side, and a small AC link power transfer inductor connected strategically between them. The voltage matching between the two bridge circuits is achieved by changing the SCVD ratio of the Switched-Capacitor Bridge circuit. These converters have several other advantages like reduced switch voltage and current stresses, inherent soft switching for some of the switches, and efficient voltage regulation. The topological evolution of two among the proposed family of converters from their corresponding isolated versions is explained. Thereafter, the circuit operation, analysis, and experimental performance verification for one of these converters are presented. The experimental results establish the suitability of the converter as the regulated first-stage of a two-stage 48 V input VRM.

A Novel Three Phase Multilevel Inverter with Single Dc Link For Induction Motor Drive Applications

Abstract: All industrial drives need a controlled output and it can be achieved by controlling the input supply. In this regard, the inverter circuit plays an important role in the applications of industrial drives. The industrial drives are operated at high rated power and the conventional inverters cannot be applicable for high power demands because of the large dV/dt (rate of change of voltage) and more switching losses. Therefore, multilevel inverters are introduced for high power-medium voltage applications. For all AC drives the MLIs are reliable in operation. This MLI topology also reduces the harmonics and bearings stress of a motor with low dV/dt. In most applications multilevel inverters are used because we can get more number of voltage levels. To increase the number of voltage levels, circuit needs to have more switches. But, we have to optimize the switch count and switching operations. The power level of the inverter is limited due to high currents and stress. In this paper, we proposed a new circuit topology which enables the switches to be active at different voltage levels, causes reduction of the switching losses and also increases the efficiency of the inverter. In this we have presented two configurations for an eleven level MLI for three phase induction motor drive application. In this an individual DC source is connected for each bridge circuit of each phase in one configuration and only one common DC link is used for three phases in another configuration. With this the size, cost and complexity could be decreased. In both the configurations the controlled output of the inverter is connected to the induction motor drive. The circuits are modeled using Matlab/simulink software and corresponding output waveforms are analyzed for both configurations.

Characterization the influences of diodes to piezoelectric energy harvester

Abstract: This study discloses the diode’s influences on the piezoelectric energy harvesting performance. The piezoelectric-based energy harvesting system plays an important role in scavenging environment vibration energy into electrical energy, which can be utilized by low-power electronic devices. With respect to the interface circuit, a full-wave bridge circuit is usually needed to rectify the alternating current (AC) signal into a direct current (DC) signal. The full-wave bridge is composed of four diodes, whose characteristics may influence the harvested power significantly. Therefore, in this paper, the diodes’ properties and influences on the energy harvesting performance are analyzed and presented via simulation and experimental studies. It is found the harvested energy has close relationship with the diode characteristics. For the high source impedance case, diode with low reverse leakage current is favorable. For the low source impedance case, diode with low forward voltage drop is favorable. The ...

Totem pole PFC circuit, pulse width control method, air conditioner and storage medium

Abstract: The invention discloses a totem-pole PFC circuit, and the circuit comprises a bridge circuit, an electric reactor, a bus capacitor and a control module, wherein the control module is used for controlling the on/off state of each switching unit and the pulse width of each switching unit during connection according to the input voltage and current of an input end of the bridge circuit when the inputcurrent of the input end of the bridge circuit is less than or equal to a preset current threshold value. The invention also discloses a pulse width control method, an air conditioner and a storage medium. The circuit achieves the selection of a proper pulse width for each switching unit according to the input voltage and current while reducing the number of switching times of each switching unit, can reduce the number of switching times under the conditions that the current harmonic requirement of the totem-pole PFC circuit is met and the power factor of the totem-pole PFC circuit is improved, so as to reduce the number of flowing times of a short-circuit current, thereby reducing the switching loss while reducing the unnecessary power in the circuit, and reducing the efficiency of the totem-pole PFC circuit.

Circuits, systems and methods for corrosion detection

Abstract: Circuits, systems and methods are provided that may be implemented using a corrosion sensor that employs a differential bridge circuit layout to detect corrosion events occurring to corrosion-sensitive components such as exposed electronic circuits. In one possible implementation, a detection circuit may be coupled to a corrosion coupon that includes the differential bridge circuit layout, and that is exposed to corrosive conditions such as ambient atmospheric conditions that contain contaminants (e.g., pollutants), humidity, particulates, etc.; as well as varying temperatures.

Clamping circuit and Y-source inverter improved in step-up ratio and capable of suppressing direct-current bus voltage spike

Abstract: The invention provides a clamping circuit and a Y-source inverter improved in step-up ratio and capable of suppressing the direct-current bus voltage spike, and relates to the technical field of inverters. The invention aims to solve the problem that an existing Z-source inverter is used for solving the problems that an existing z-source inverter is limited in power level and low in circuit utilization efficiency. The cathode of a diode D2 is simultaneously connected with one end of a capacitor C3 and one end of an inductor L0. The two ends of a capacitor C4 are respectively connected with theanode of the diode D2 and the other end of the inductor L0. The anode of the diode D2 and the other end of the capacitor C3 are used as the voltage input end of the clamping circuit. The other end ofthe inductor L0 and the other end of the capacitor C3 are used as the voltage output end of the clamping circuit. The voltage output end of the Y-source network circuit is connected with the voltageinput end of the clamping circuit. The voltage output end of the clamping circuit is connected with the voltage input end of an inverter bridge circuit. The inverter bridge circuit is used for supplying power to a load or a power grid.

Bidirectional energy storage converter

Abstract: The invention discloses a bidirectional energy storage converter, and relates to the technical field of power transmission and transformation. The bidirectional energy storage converter comprises a plurality of DC boost-buck units, a three-phase inversion bridge circuit, a controller, an adaptor, an AC filtering circuit, an isolation transformer and an AC EMI filter, wherein the AC EMI filter is connected with an AC bus, the AC bus is connected with a power grid by an AC circuit breaker, a high-voltage end of the isolation transformer is connected with the AC EMI filter, a low-voltage end of the isolation transformer is connected with an AC output end of the three-phase bridge inverter and an AC input end of the adaptor, a DC input end of the three-phase bridge inverter is connected with the DC boost-buck units, and a sampling signal input end of the controller is connected with a DC input end/AC output end of the three-phase bridge inverter and a DC output end/AC input end of the adaptor. By the bidirectional energy storage converter, bidirectional energy flowing of the AC system and the DC system can be achieved, multi-path DC inputs of multiple paths of different types of DC power supplies also can be achieved, peak clipping and valley filling of a power grid load can be achieved, and the bidirectional energy storage converter also has the functions of emergency power supply, reactive power compensation, electric energy quality control and the like.

Effect of channel geometry on ionic current signal of a bridge circuit based microfluidic channel

Abstract: Bridge circuit based ionic current sensing in a microfluidic channel has attracted attention as a highly sensitive analytical method for bio-related molecules and particles. However, channel geometry which greatly influences the detected ionic current has not been investigated. Here, we investigate experimentally and theoretically the effect of differences in the microfluidic channel geometry on shapes and amplitude of signals in ionic current sensing. Our results clarify the geometrical effect of the channel in the bridge circuit based ionic current sensing method.

Bidirectional DC who mixes humorous mode of vibration circuit and two active bridge circuit

Abstract: The utility model discloses a bidirectional DC who mixes humorous mode of vibration circuit and two active bridge circuit. Adopt two kinds of modules, be defined as I module of type and type II modules, through a port series connection with these modules, and parallelly connected power grade and the higher bidirectional DC of electric pressure of constituteing of another port. The use number of two kinds of modules is not limit, nevertheless every kind at least 1. Wherein, I module of type comprises a DAB circuit, II modules of type comprise the circuit based on LC resonance technology. The utility model discloses a bidirectional DC can be through to freely the controlling of DAB circuit in I module of all types, realizes whole bidirectional DC's frequency control, improves its operating efficiency or control performance.

Power conversion device and air conditioner comprising the same

Abstract: The invention provides a power conversion device and an air conditioner comprising the same, and power conversion can be efficiently performed. The control portion (15) of the power conversion device(1) executes synchronous rectification control, in switch elements (Q1, Q4) included by a current path of a smoothing capacitor (C1), the switch element (Q1) connected with the positive pole of the smoothing capacitor (C1) is in on state in at least a part of period when current flowing in a bridge circuit (10), and the switch elements (Q2, Q3) which are not be included by the current path maintain in off state.

Design of Linear Capillary Measuring Transducers for Low Gas Flow Rates

Abstract: The performed analysis of known capillary flowmeters for low gas flows reveals the prospect of constructing the primary measuring transducers of flowmeters with a linear output signal. Owing to the stability of dimensions of the pass-through channels in glass capillaries channels such flowmeters can demonstrate high metrological characteristics. In this regard, we have investigated the capillary as a sensing element in the primary transducers of flowmeters for low gas flows.Different circuits of capillary primary transducers for the measuring instruments of low gas flow rate have been examined. Our study makes it possible to select the optimal circuit of a primary measuring transducer based on the measurement range, as well as the number and size of the pass-through channels in capillaries. For example, the flow meter based on a package of capillaries demonstrates a wider measurement range compared to other schemes.We have derived analytical dependences that enable the design of single- capillary, package, and bridge transducers. Comparative characteristics of the specified primary measuring transducers are provided. We have constructed algorithms for calculating dimensions of channels in the capillaries of transducers with a linear output signal.The influence of temperature and barometric pressure on a deviation in the static characteristic of the transducer has been estimated. It was established that the bridge circuit, unlike others, ensures partial compensation for the influence of external factors.We have designed and investigated a capillary oxygen flowmeter, constructed using the bridge measurement circuit with a linear conversion function, intended for an automated system of the manufacturing process of workpieces for fiber light guides. The upper limit of measurement by the flowmeter is at the level of 54 l/h, its basic relative error is 0.8 %

Electronic smoking set's device that generates heat

Abstract: The utility model relates to an electronic smoking set's device that generates heat, this electronic smoking set's device that generates heat's microcontroller electricity in proper order meet back microcontroller after connecting lift breaking the bridge circuit, the unit resistance of generating heat sampling circuit, the unit that generates heat, the unit resistance of generating heat detectionmodule, generate heat unit sampling circuit and resistance detection module connects, lift breaking the bridge circuit with it is connected with feedback circuit to generate heat between the unit, feedback circuit meets back microcontroller, when electronic smoking set in the use, also corresponding changing of resistance during the temperature variation of the unit that generates heat, the unitresistance of generating heat detection module detects the resistance of the unit that generates heat and converts corresponding temperature electric signal to and passes to microcontroller, microcontroller sends feedback circuit 0 according to this temperature electric signal and to set the temperature value after relatively and gives lift breaking the bridge circuit for the output voltage of lift breaking the bridge circuit changes, thereby generates heat the generate heat stability of unit temperature of adjustment that also changes of the power of unit.

Wireless power transmitter and method for wirelessly transmitting power

Abstract: A wireless power transmitter includes: a converter including switching elements forming a bridge circuit, wherein the converter is configured to output an alternating current (AC) voltage including a frequency determined according to an operating frequency of at least one switching element among the switching elements; a resonator including an inductor and a capacitor, and configured to receive the AC voltage to wirelessly transmit power; and a controller configured to output control signals controlling the switching elements so that the converter performs a first mode operation in which an operating duty cycle is fixed and the operating frequency is varied, and an operation of the converter is switched from the first mode operation to a second mode operation in which the operating frequency is fixed and the operating duty cycle is varied, in response to the operating frequency reaching a first reference frequency

Wide load range boost type power factor correction converter

Abstract: The invention discloses a wide load range boost type power factor correction converter, comprising a main circuit (1) and a control circuit (2). The main circuit (1) comprises an AC source (3), a rectifier bridge circuit (4), a Boost circuit (5), and a load (6). The control circuit (2) comprises a duty ratio compensation module (7), a prediction current control module (8), and a PWM module (9). The invention is characterized in that the output of the AC source (3) is connected to the input of the rectifier bridge circuit (4), turning into steamed bread wave, which is used as the input end of the Boost circuit (5); the load (6) is connected to two ends of the output capacitor (Co) of the Boost circuit (5) in parallel; the control circuit parts (7, 8, 9) are control signals in the internal DSP; the output of the duty ratio compensation module (7) and the prediction current control module (8) is used as the input of the PWM module (10). The invention is advantageous in that the problem ofcurrent oscillation caused by parasitic parameter when a PFC converter is lightly loaded can be resolved; current oscillation can be inhibited through improving a control algorithm; being different from a conventional buffer circuit, the wide load range boost type power factor correction converter will not bring extra loss, and thereby the efficiency of the converter can be effectively improved.

Analysis of SiC MOSFET Switching Performance and Driving Circuit

Abstract: The switching characteristic of silicon carbide (SiC) MOSFET and silicon (Si) MOSFET are compared and analyzed in this paper. SiC MOSFET has advantage of low losses by capturing the switching trajectories. A driving resistance analysis model in switching process is proposed. Driving circuits of SiC MOSFET for different power converters are analyzed. In addition, the crosstalk of bridge circuit is discussed. The method of suppressing the crosstalk spikes in the bridge circuit is given and is simulated by LTspice. The result of simulation proves the suppression function to the spikes of driving circuits and the feature of each circuit is summarized. Finally, a better design of layout for driving circuits is given, compared with the traditional design, the switching loss in the circuit can be reduced. The theoretical basis is provided for driving circuit of SiC MOSFET in practical application.

Inverter circuit with current detection circuitry

Abstract: An inverter circuit with a current detection circuitry includes a main bridge circuit connected between the pair of DC input nodes, the main bridge circuit converting the received DC voltage to a primary AC current so as to output the primary AC current through an output terminal to be connected to a load; a supplementary bridge circuit connected in parallel to the main bridge circuit between the pair of DC input nodes, the supplementary bridge circuit having a circuit configuration identical to that of the main bridge circuit with smaller circuit parameters in at least some of constituent circuit elements so as to generate a detection-use AC current that is a prescribed fraction of said AC current outputted by the main bridge circuit. The detection-use AC current is detected by a current detector so as to calculate the amount of the primary AC current.

Improved wide load range boost type power factor correction converter

Abstract: The invention discloses an improved wide load range boost type power factor correction converter, comprising a main circuit (1) and a control circuit (2). The main circuit (1) comprises an AC source (3), a rectifier bridge circuit (4), a Boost circuit (5), and a load (6). The control circuit (2) comprises a sampling correction module (7), a voltage loop module (8), a current loop module (9), and aPWM module (10). The invention is characterized in that the output of the AC source (3) is connected to the input of the rectifier bridge circuit (4), turning into steamed bread wave, which is used as the input end of the Boost circuit (5); the load (6) is connected to two ends of the output capacitor (Co) of the Boost circuit (5) in parallel; the control circuit parts (7, 8, 9, 10) are control signals in the internal DSP; the output of the sampling correction module (7) and the voltage ring module (8) is used as the input of the current ring module (9), and the output of the current ring module (9) is used as the input of the PWM module (10). The invention is advantageous in that when a converter works in a CCM mode, the correction method brought forward will not affect the duty ratio; as for the PFC converter with wide-load range, the same program is adopted for correction, and the calculation time of the program can be reduced.

Magnetic pulse inducted transfer-type DC circuit breaker

Abstract: The present invention discloses a magnetic pulse inducted transfer-type DC circuit breaker. The DC circuit breaker comprises a main current circuit and a transfer current circuit, the main current circuit comprising a combination of a fast mechanical switch or a mechanical switch with a power electronic device; the transfer current circuit comprises an arrester and a mutual inductor. The voltage generated through a mutual inductor may directly transfer current to the arrestor, thereby eliminating a process of transfer of the current to the capacitor or a power electronic device; it has a high current limiting or breaking speed, with a stability far superior to traditional technologies. The isolation between the capacitance charging unit and the DC system significantly reduces the voltage level and size of the charging unit, and enhances action reliability. The power semiconductor devices or trigger gaps are used at the primary side of the mutual inductor of the transfer current circuit form a bridge circuit, thereby realizing bidirectional current transfer; the bridge circuit is voltage-withstanding and low-cost.

Motor control circuit

Abstract: The utility model provides a motor control circuit includes: the voltage conversion circuit that the input links to each other with the power input end, the continuous microprocessor of output with voltage conversion circuit, the motor -drive circuit that control end and microprocessor's output links to each other, motor -drive circuit's input and power input end link to each other, and the outputlinks to each other with the motor, disposes the full -bridge circuit in the motor -drive circuit, counter the drag electromotive force steering circuit of setting between motor -drive circuit and voltage conversion circuit input for the anti - input that drags the electromotive force to voltage conversion circuit of guide motor -drive circuit output, sampling circuit for the anti - electromotiveforce that drags to the motor produces is sampled, sends sampled signal to microprocessor, microprocessor is used for: when sampling circuit output's sampled signal was greater than the setting value, output was used for controlling motor braking's control signal Thereby prevented that the anti - electromotive force that drags from giving the damage that the circuit device caused

Wind tunnel balance temperature drift correction method

Abstract: The invention discloses a wind tunnel balance temperature drift correction method. Temperature characteristics of various strain gauges arranged on a balance element are measured by means of a groundtemperature test chamber, and function relations that resistance values of the various strain gauges change along with the temperatures are obtained; then corresponding strain gauge resistance valuesare calculated according to the strain gauge temperatures in the test process, and output of a bridge circuit is calculated by means of a Wheatstone bridge calculation formula and represents as a function of the balance bridge circuit feature temperature at the moment; and finally the formula is corrected according to a balance initial read number in an actual wind tunnel test and three data obtained in the same force and pose state, and a final curve that the balance bridge circuit initial read number changes along with the feature temperature in the test is obtained. By means of the method,wind tunnel balance temperature drift caused by the temperature gradient can be corrected, and particularly, the bridge circuit of which the temperature effect is nonlinear also can be well corrected;the method is not only suitable for an intermittent wind tunnel, but also can be applied to a continuous wind tunnel and can achieve a good correction effect both on the intermittent wind tunnel andon the continuous wind tunnel; and the applicable temperature range of the method is wider.

Electric power conversion system and air conditioner

Abstract: PROBLEM TO BE SOLVED: To provide an electric power conversion system capable of preventing destruction of an element even at a low cost.SOLUTION: The electric power conversion system includes: a first drive circuit (IC1) which drives first and second switching elements (Q1, Q2), detects the presence/absence of an overcurrent in an electric current running through a bridge circuit and has an output terminal (a Fault terminal) outputting a predetermined voltage signal (0 V) when an overcurrent current is detected; a second drive circuit (IC2) which drives third and fourth switching elements (Q3, Q4); and a transmission elements (D5, D6) which is connected between the output terminal (Fault terminal) of the first drive circuit (IC1) and input terminals (LIN, HIN) of the second drive circuit (IC2) and transmits a voltage signal (0 V) to the input terminals (LIN, HIN).SELECTED DRAWING: Figure 2

DC/DC converter structure for high-gain fuel cell vehicle and control method

Abstract: The invention provides a DC/DC converter structure for a high-gain fuel cell vehicle and a control method and belongs to the field of power system design and application for new energy vehicles. The DC/DC converter structure comprises an upper bridge circuit and a lower bridge circuit which are symmetrically arranged in structure and are connected in parallel, wherein the upper bridge circuit comprises a first inductor, a second switch tube, a second inductor, a second conducting diode and a first capacitor connected in series; a positive electrode terminal of a fuel cell is connected with a first switch tube through the first inductor and then connected to a negative electrode terminal of the fuel cell; the positive electrode terminal of the fuel cell is connected to a midpoint of the second switch tube and the second inductor through a first conducting diode; and the midpoint of the second inductor and the second conducting diode is connected with the negative electrode terminal of the fuel cell through a third switch tube. According to the DC/DC converter structure, the disadvantage of a low boost ratio of a traditional boost topology is avoided, the disturbance of input voltageto output voltage during wide range variation is offset and the overhigh cost is avoided.

Electric bridge balancing circuit

Abstract: The utility model provides an electric bridge balancing circuit relates to bridge balance technical field. Electric bridge balancing circuit mainly includes wheatstone bridge circuit, differential amplification circuit, sampling circuit and singlechip. Wheatstone bridge circuit comprises with digital potentiometer resistance, differential amplification circuit is used for linear amplification analog signal, sampling circuit is used for trunning into analog signal to data signal, the singlechip is used for the resistance according to signal change automatic control digital potentiometer, keepsthe bridge balance. The utility model discloses a real -time detection wheatstone bridge circuit output signal's change adopts single chip microcomputer control digital potentiometer's resistance to change messenger bridge circuit keep balance.

PM2.5 Particle Detection in a Microfluidic Device by Using Ionic Current Sensing.

Abstract: We have demonstrated a PM2.5 analysis method that adds information on the number concentration and size by using microfluidic-based ionic current sensing with a bridge circuit. The bridge circuit allows for suppression of the background current and the detection of small PM2.5 particles, even if a relatively large micropore is used. This is the first demonstration of the detection of PM2.5 particles via ionic current sensing; our method enables analyses of both the number concentration and size.

Intelligent power module

Abstract: The invention provides an intelligent power module. The intelligent power module comprises a three-phase bridge driving unit, a PFC (power factor correction) simulation unit, a PFC driving unit, a functional protection unit, a three-phase bridge circuit, a rectifier bridge unit, a step-down voltage regulation unit, a logic-driving signal processor, a PFC switch unit and an alternating voltage detection unit. By integrating the three-phase bridge driving unit, the PFC simulation unit and the PFC driving unit, the intelligent power module is endowed with a PFC function, high power factor of theintelligent power module is realized, and burden of a power grid when the intelligent power module drives three-phase load is reduced.

Square wave motor control system and square wave motor adopting the same

Abstract: The invention belongs to the technical field of the power electronics and the motor driving control, and especially relates to a square wave motor control system and a square wave motor adopting the same. The square wave motor control system comprises a driving device and a controller; the driving device comprises a DC power supply and an inversion device; a DC side of the inversion device is respectively connected with positive and negative electrodes of the DC power supply, and the AC side is connected with the motor; the inversion device comprises a full-bridge inversion circuit, and a lower half bridge arm of each bridge circuit is connected with a sampling resistor for detecting corresponding bridge arm current in series; the controller controls an inverter by using a driving signal modulated by an upper bridge arm power tube and reached by a lower bridge arm power tube through the adoption of a pairwise switch-on mode in one modulation section; and the controller comprises a current sampling circuit connected with the sampling resistor. An aim of simplifying the structure of the square wave motor control system is realized, the controller is simple in structure and small in volume, and the cost is reduced.

Radiation Sensors Based on Field-Effect and Unijunction Transistors

Abstract: The possibility of increasing the sensitivity of radiation sensors based on the field effect transistors is experimentally studied. A bridge circuit connecting two transistors with positive sign of the radiation sensitivity and two transistors with negative sign of the radiation sensitivity makes it possible to increase the dependence of the output voltage in the bridge diagonal on the absorbed radiation dose by an order of magnitude. The frequency sensor-converter of radiation designed on a unijunction transistor according to the circuit of the relaxation oscillator has the minimum number of individually attached components. The replacement of the resistor setting the current in the emitter circuit with a field-effect transistor sensitive to radiation increases the sensor sensitivity 5–10 times.