Multi-channel 3-phase fast response signal conditioner for high-sampling HV/HC measurments

Machine tool core subsystems - processing units (spindle, axes) consume variable amount of power, which greatly depends on the processing parameters (feed rate, spindle speed, depth of cut etc.) and its power demand has fast changing transients which cannot be precisely captured with a standard industrial power meter. Moreover, as far as drive unit of a machine (control of all the drives and axes) is nowadays a single module, independent measurement of a few spindles simultaneously can only be done directly at the motor leads. Currents feeding motor winding are driven by pulse with modulated (PWM) voltages, typically switching frequency of 4-8kHz. To accurately measure these type of signals, a high bandwidth, three-phase, isolated signal conditioning board has been developed to interface high power loads with acquisition instrumentati. Designed board has operational bandwidth of 120kHz, with gain and cut-off frequency programmable by an I2C interface. For multi-channel acquisition (several three-phase subsystems), five boards were enclosed in a portable enclosure, with power supply and microcontroller system for gain and filter setup (via external ethernet port).