Altera Multiaxis Motor Control Board - Manual (Page 9)

Functional Description Page 9
Multiaxis Motor Control Board February 2014 Altera Corporation
DC Link Monitor
The Multiaxis Motor Control Board measures the DC Link voltage, V
DCLINK,
by
sensing the voltage across a resistor divider chain representing:
82/199682 * V
DCLINK
For example, a voltage of 41 mV corresponds to a DC link voltage of 100 V. The
sigma-delta modulated reading is available on the HSMC connector
HSMC_ADC_400V_PFC_V_DATA
signal.
After filtering in the FPGA, the Multiaxis Motor Control Board calculates the DC link
voltage, according to the equation:
DC link voltage (V) = ADC value × 0.048
The reference design software uses an equivalent formula based on integer arithmetic.
The Multiaxis Motor Control Board measures the ground return current of the PFC by
sensing the voltage across a 0.01 Ohm resistor in the ground return path. The sigma-
delta modulated reading is available on the HSMC connector
HSMC_ADC_400V_PFC_I_DATA
signal.
After filtering in the FPGA, the Multiaxis Motor Control Board calculates the the DC
link return current, according to the equation:
DC Link return current (mA) = ADC value × 1.95
The reference design software uses an equivalent formula based on integer arithmetic.
IGBT Return Current
The Multiaxis Motor Control Board measures the ground return currents of the IGBT
modules by sensing the voltage across 0.05 Ohm resistors in the ground return paths.
The sigma-delta modulated readings are available on the HSMC connector
DRV_x_HSMC_MOTOR_RTN_DATA_OUT
signals.
After filtering in the FPGA, the Multiaxis Motor Control Board calculates the IGBT
return current according to the equation:
I (mA) = ADC value × 0.195
The drive on chip reference design software uses an equivalent formula based on
integer arithmetic.
Motor Phase Currents
Currents are measured in two of the three phases, U and W, by sensing the voltages
across 0.05 Ohm shunt resistors in series with the motor connections. The Vin+
terminals of the ADCs are connected nearest the motor. The Vin– terminals of the
ADCs are connected nearest the IGBT module.
After filtering in the FPGA, the Multiaxis Motor Control Board calculates motor phase
current according to the equation:
I (mA) = ADC value × 0.195
The reference design software uses an equivalent formula based on integer arithmetic.
The sigma-delta modulated readings are available on the HSMC connector
DRV_x_HSMC_U_DATA_OUT
and DRV_x_HSMC_W_DATA_OUT signals.