Application Cases

Experiment Name: Testing of Underwater Ultrasonic Wireless Power Transfer System

Research Direction:
With the rapid advancement of technology, it has become evident that the exploration, development, and utilization of marine resources, as well as marine environmental monitoring, rely heavily on a multitude of underwater electromechanical and sensing devices. To ensure the real-time performance, reliability, and uninterrupted operation of these underwater electromechanical devices, it is essential to provide them with safe and convenient power replenishment. However, traditional power supply methods suffer from high costs, poor flexibility, safety risks, and limitations imposed by charging distance and seawater depth. Consequently, wireless power transfer technology for underwater devices has garnered significant attention. Ultrasonic waves, owing to their advantages such as high directivity, long propagation distance, low acoustic attenuation, and absence of electromagnetic interference in seawater media, make ultrasonic wireless power transfer technology an effective solution for powering underwater devices. This study conducts experiments to investigate the feasibility of ultrasonic wireless power transfer and the key parameters affecting its efficiency.

Experimental Objective:
To explore the effects of load resistance, input voltage, transmission distance, and receiving transducers on the output power and transmission efficiency of an ultrasonic wireless power transfer system using a self-built experimental platform.

Test Equipment:
Signal generator, ATA-4014 high-voltage power amplifier, transmitting/receiving transducers, oscilloscope, etc.

Experimental Procedure:
An AFG30122 signal generator outputs a sinusoidal signal matching the resonant frequency of the transmitting transducer. The electrical signal is amplified by an ATA-4014 high-voltage power amplifier to drive the transmitting transducer, converting the electrical signal into an ultrasonic signal for transmission to the receiving transducer. The receiving transducer reconverts the received ultrasonic signal back into an electrical signal. An oscilloscope is used to measure the voltage output from the receiving transducer and the voltage across the load resistor.

Experimental Results:
Test Conditions: Transmission distance: 30 cm; Load resistance: 38.5 Ω.

As the input voltage increased from 20 V to 70 V, the output power gradually rose from 0.2 W to 2.11 W. However, the transmission efficiency showed a declining trend. When the transducer operates underwater, its equivalent circuit consists of a static capacitance and a dynamic resistance in parallel, resulting in a capacitive system. According to AC circuit theory, a phase difference $\theta$ inevitably exists between the current and voltage applied to the piezoelectric transducer, leading to reactive power. This reactive power reduces the output of active power and the efficiency of the excitation source while increasing electrical energy losses in the circuit. In severe cases, it can cause significant heating of the transducer, further reducing energy conversion efficiency.

Under different input voltages, the output current, phase difference, effective input power, and output voltage across the receiving transducer under no-load conditions are shown in Figure 2. As the input voltage increased, both the input current and the output voltage across the receiving transducer gradually increased. Simultaneously, the phase difference between the input voltage and current also increased, with $\theta$ rising from 20° to 35°. As shown in Figure 2(b), at an input voltage of 60 V, there is a 30° phase difference between the input current and output voltage.

Figure 2: Output Power and Energy Transmission Efficiency of the Underwater UWET System Under Different Input Voltages

Product Recommendation: ATA-4014C High-Voltage Power Amplifier

Figure: ATA-4014C High-Voltage Power Amplifier Specifications

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