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Use of IGBTs in Medical Ultrasonography Machines

Insulated Gate Bipolar Transistors or IGBTs are widely used in medical ultrasonography machines to support precise and high voltage pulse generation required for diagnostic imaging. Ultrasound technology is essential in many medical fields including cardiology, obstetrics, urology, neonatology, and gastroenterology, where it is used for non invasive diagnosis and treatment.
Ultrasound refers to sound waves with frequencies above the range of human hearing. In medical imaging, ultrasound frequencies typically range from 2 to 18 megahertz. The selection of frequency involves a balance between image resolution and pe*******on depth. Lower frequencies pe*****te deeper into the body but produce lower resolution images, while higher frequencies provide clearer images with reduced depth.
A handheld probe is used during sonography and is placed over the patient’s body to capture real time images. The probe contains a piezoelectric transducer with a phased array system that allows control of the direction and depth of the sound waves. These waves reflect off internal organs at varying intensities depending on tissue composition. The time taken for echoes to return is used to calculate distance and generate detailed diagnostic images.
To produce ultrasound waves, a high voltage pulse is applied to the piezoelectric material inside the transducer. This pulse often exceeds 1000 volts with current levels between 20 and 50 amperes. However, because the pulse duration is extremely short, typically around 0.5 microseconds and at a repetition rate of about 200 hertz, efficient power control is required.
IGBTs are used in this process to manage energy delivery effectively. The system works by slowly charging a capacitor through a diode while the IGBT is off. The IGBT then turns on briefly to discharge the capacitor through the transducer, producing the required high energy pulse. This method ensures precise control, high efficiency, and reliable operation in medical ultrasound systems.

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Benefits of IGBT Switching Speed in Elevators

Insulated Gate Bipolar Transistors or IGBTs play a crucial role in modern elevator systems, especially in Pulse Width Modulation Variable Frequency Drives or PWM VFDs. These systems require very fast switching speeds, which IGBTs can achieve efficiently by turning on and off several thousand times per second.
A typical VFD IGBT can turn on in less than 400 nanoseconds and turn off in about 500 nanoseconds. It operates using three terminals: gate, collector, and emitter. When a positive voltage, usually around 15 volts DC, is applied to the gate, the IGBT turns on and allows current to flow between the collector and emitter. This is similar to closing a switch. When the voltage is removed, the device turns off, often with a small negative voltage applied to ensure stability and prevent accidental activation.
IGBTs are widely used in modern variable frequency drives because they enable precise motor control and improved energy efficiency. One major benefit in elevator applications is the ability to use high switching frequencies that move beyond the audible range, significantly reducing motor noise and improving passenger comfort.
However, the fast switching speed of IGBTs can generate radio frequency interference due to sharp voltage waveforms. This interference may affect AM radio signals and sensitive electronic equipment such as computers, medical devices, and elevator control systems if proper shielding and wiring practices are not followed.
In elevator machine rooms, poor layout or improper grounding can allow electrical noise from VFD systems to interfere with controller performance. Therefore, careful system design is essential to ensure reliable operation.
Despite these challenges, the high switching speed, simple control, and strong overload capability of IGBTs make them a key component in modern elevator drive systems, improving performance, efficiency, and ride quality.

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