System and method for ultrasonic transducer control

A system for controlling an ultrasonic transducer, the system comprising:

• a control processor;
• a waveform generator that produces an oscillating signal, wherein the frequency of the oscillating signal is adjustable under control of the control processor;
• power circuitry that receives the oscillating signal and drives the ultrasonic transducer to vibrate at the frequency of the oscillating signal, wherein the power circuitry further comprises a power amplifier that receives the oscillating signal and produces an amplified oscillating signal, and a high frequency transformer that includes a primary winding and a secondary winding, wherein the primary winding receives the amplified oscillating signal and the secondary winding is coupled to the ultrasonic transducer, the output of the secondary winding driving the ultrasonic transducer;
• a current sensing circuit that senses the current passing through the ultrasonic transducer;
• a voltage sensing circuit that senses the voltage on the ultrasonic transducer;
• and
• a phase detection circuit that receives signals from the current sensing circuit and the voltage sensing circuit and produces an indication of the relative phase of the voltage and the current and provides the indication to the control processor;
• wherein the control processor is configured to repeatedly read the indication of the relative phase of the voltage and the current and adjust the frequency of the oscillating signal so as to control the indication of relative phase of the voltage and the current to a value that has been preselected to correspond to resonance of an electromechanical system that includes the ultrasonic transducer;
• and wherein the control processor adjusts the frequency of the oscillating signal according to a proportional-integral control law.