![]() A simplified model of a piezoelectric transducer is shown. Avoid touching any part of the high-voltage components and connections.Ĥ. The red trace indicates a high-voltage connection.Ĭaution: With the high-voltage circuit presented in Figure 3 and the rest of the discussion, use high-voltage engineering techniques such as high-voltage wire plus connector. A series inductor is used to boost piezo transducer voltage. The next three sections offer detailed explanations on how a series-resonance circuit can boost voltage for capacitive devices.ģ. Voltage boosting can be accomplished by adding a series inductor (Fig. A series-resonant technique can boost the driving voltage and become a high-voltage driver and generator. Fortunately, there’s simple solution to enable a lower-voltage piezoelectric amplifier to boost to higher voltages. ![]() It’s increasingly difficult and expensive to obtain high voltage and still achieve a high-frequency and high-current PZT driver amplifier. For example, a piezo amp driver’s maximum output is 80 V p-p, but the required voltage is in the hundreds or even the thousands and still must maintain high frequency. There are usage cases where the piezo actuator and other devices require higher driving voltage than the driver can supply. 2, again) is the most straightforward to work with. At higher frequencies, it often requires even more driving current.Īs long as the PZT driver can output the required voltage, current, and frequency, the direct-drive method (Fig. Using direct drive, a high-current piezoelectric driver amplifier is needed. Let’s use the following example: a piezoelectric actuator with 1-♟ capacitance, operating at 18 kHz, which requires 40 V peak-to-peak and a peak current of 4.5 A (9 A p-p). The current symbol is I, the voltage symbol is V, C is the capacitance, and f is the frequency. The current is directly proportional to voltage, frequency, and capacitance as indicated in Equation 3. Substituting Z = 1/(2πf) into Equation 2 yields Equation 3. The PZT actuator current is formulated by Ohm’s law in Equation 1. Because of low impedance, a fairly high-current piezo driver amplifier is required, especially at ultrasonic frequencies. If the frequency is high, their impedance is low due to their large capacitance. PZT transducers and motors are very capacitive in nature. The TS250 piezoelectric driver amplifier directly drives a high-capacitance transducer.Ī piezo amplifier driver is commonly used for direct driving of high-frequency and high-capacitance transducers such as actuators, buzzers, motors, etc. It’s the recommended method for driving piezo motors and elements if the PZT driver met the voltage and power requirements.Ģ. Most of the time, piezo elements are driven this way. A direct driving method offers direct control over voltage range and waveform shape (sine vs. The most convenient way to drive piezoelectric actuators and other devices is to connect them to the piezo driver (Fig. But first let’s look at the non-resonant driving method, then compared to the resonant method. This article shows how a series-resonant technique can handle the challenge by boosting the output voltage. Certain devices require low voltage in the few tens of volts, while others need hundreds and even thousands of volts.ĭriving PZT devices that require high voltage, oftentimes accompanied by high frequency and high capacitance, can be very challenging. Some only require dc voltages, while others need ac voltage waveforms such as sine and square. These PZT devices operate over a very wide range of voltages, frequency, and waveforms. Example of such devices include piezo motors, actuators, speakers/buzzers, ultrasound devices for imaging and levitation, high-power ultrasonic transducers for cleaning, etc. Today, most piezo devices (sometimes referred to as PZT) use the inverse piezoelectric effect. In turn, we’ve seen the creation of a wide range of practical piezoelectric devices. It’s been more than 100 years since the discovery, and during that time numerous scientific research efforts have led to the invention of many superior piezo materials. An ac sinewave applied to a piezo device causes the material to expand and contract. When voltage potential is applied to certain ceramic materials, they expand and contract physically as shown in Figure 1.ġ. The inverse piezoelectric effect is when the process occurs in reverse. When some solid material is mechanically compressed or stressed, the material accumulates electrical charges on its surface and develops a voltage potential. Jacques and Pierre Curie, French physics, discovered the piezoelectric effect in 1880.
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