Driving power amplifier circuit of the hottest ult

2022-08-02
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Ultrasonic motor driving power amplification circuit

the signal driving the ultrasonic motor must be a high-frequency and high-voltage signal with certain power, and there are two main ways to generate high-frequency and high-voltage: one is to use the traditional switching power supply technology combined with the transformer to achieve voltage rise, but the transformer must match with different types of ultrasonic motors, which is not conducive to miniaturization and generalization. Second, the characteristics of ultra

acoustic motor, such as equivalent circuit parameters, are used to realize the transformer free drive of ultrasonic motor. This drive circuit can effectively reduce the volume and cost, and is convenient for integrated production. It is suitable for small portable equipment with small power of ultrasonic motor and products with strict requirements on volume and weight, such as focusing of camera, aviation, aerospace and other fields

The

switch inverter driving circuit is an ultrasonic motor driving circuit based on the inverse piezoelectric principle. According to its different structure and application requirements, it is easy to use and has different circuit topologies. There are three kinds of switching inverter drive circuits based on mosfe: push-pull converter, full bridge converter and half bridge converter. Push-pull switching circuit is a typical switching inverter circuit, so this paper only introduces the push-pull switching circuit. Among them, QL and Q2 are conducted alternately, and the two windings at the primary side of the transformer form an AC voltage with opposite phases respectively. Its outstanding advantage is that the circuit is symmetrical. The driving circuits of the two switches have a common ground and do not need to be driven separately, which can simplify the circuit design. The push-pull converter has the simplest circuit structure and high transformer utilization. It is especially suitable for ultrasonic motor drive with low voltage supply. However, considering the safety problem, the rated voltage of each switch should be 3.3 times 5 of the input voltage. This circuit structure has been widely used in the ultrasonic motor driver of Shinsei company in Japan, the ultrasonic motor made by Southeast University and Nanjing University of Aeronautics and Astronautics

the typical switch inverter drive circuit with push-pull circuit does not allow two switches in series to be connected at the same time, otherwise the switch will be damaged. The square wave signal with 50% duty cycle cannot be used for driving, and the dead zone must be set for the two drive signals

the resonant voltage increasing driving circuit is based on the capacitive load characteristics of the ultrasonic motor, takes the ultrasonic motor itself as a component of the circuit, matches other j-components to form a white oscillation circuit, and participates in the generation of the driving signal when the load can no longer rise. Making full use of the unchangeable resonant boost circuit, which needs to be connected to the baby's nose, mouth or venous booster, not only reduces the volume of the driver, but also creates conditions for the universality and miniaturization of the driver. According to the principle and topology of the resonant circuit, the LC and LLCC resonant boost circuits are introduced below

the ultrasonic motor itself is a capacitive load relative to the driving circuit, so only one inductance in series is required to form an LC resonant circuit. Its basic principle is boost power. When the switch SW L is closed, the power supply is stored to the inductor; When the switch is disconnected, the stored energy in the inductance releases energy to the capacitor C and resonates with it

llcc converter in most traditional driving modes, the quality factors of two-phase circuits are different and change with time. When the hardware configuration of the series resonant inverter is different and the switching frequency and harmonic frequency tend to be constant, the change of quality factor will cause serious distortion of voltage gain and lead to instability of two-phase output voltage at the same switching frequency. In order to solve this problem, the latest formulation is to use the high-order inverter, i.e. LLCC converter circuit, to topology the traditional resonant circuit. The LLCC resonant boost circuit contains the advantages of the third-order LCC and LLC inverters

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