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11 PDUS210 Operation
11.1 Overview
The operating principle of the PDUS210 is summarized in Figure 5. The transducer on the right is
connected to the output transformer. The transformer converts the internal +/-24V drive voltage to
the desired output voltage range, for example +/-200V. By default, the output connection to the
transducer is electrically isolated from ground but the negative output can also be internally
grounded using the jumper shown.
During operation, the voltage and current in the transducer is used to estimate the phase ��. The
measured phase is then used to control the frequency of the signal generator by comparing it to the
phase set point ��
. The frequency controller stabilizes the feedback loop and controls the settling
������
time of the closed loop system. The feedback gain is normally determined experimentally by slowly
increasing the gain until the desired performance is reached or the response begins to become
unstable.
The signal generator has a variable amplitude, and the frequency is normally controlled by the phase
control loop. It is connected to the power amplifier, which drives the output transformer and
transducer.
Phase
Frequency
Signal
Power
Setpoint
Controller
Generator
Amplifier
Transformer
Transducer
Ground
Connection
Phase Detector
Figure 5. PDUS210 operation (in constant voltage, resonance tracking mode).
11.2 Resonance Tracking
The resonance tracking system of the PDUS210 is illustrated Figure 5. The phase detector measures
the impedance phase angle between the primary voltage and current. The frequency controller ��
(��)
��
varies the drive frequency to maintain a constant phase set point ��
, which is usually equal to zero.
������
To operate at a series resonance (impedance minima), the phase controller gain must be positive to
create a stable operating point.
PDUS210 V5 Manual
10
Modified 17/12/2022
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