Visible to Intel only — GUID: qiz1468414644226
Ixiasoft
Visible to Intel only — GUID: qiz1468414644226
Ixiasoft
5.3. Scale Factors for the Drive-on-Chip Design Example in the GUI
Item | Sigma Delta Scaling |
---|---|
Motor Phase Voltages | 545 counts/A |
DC Bus Voltage | 545 counts/V |
Input Voltage | 895 counts/V |
Input Current | 252 counts/A |
Inductor Current | 717 counts/A |
DC Bus Current | 1638 counts/A |
Motor Phase Currents | 1.024 counts/mA |
Item | Sigma Delta Scaling (counts/mA) |
---|---|
Id Direct Current | 1.024 |
Iq Quadrature Current | 1.024 |
SVM Voltage
The design calculates the maximum count of the PWM from the PWM frequency , and passes it to the software from the system.h header file generated with the Nios V/g BSP. The maximum count varies with the PWM clock frequency and sample rate and is (PWM frequency in Hz)/( (Sample rate) *1000). For example, with a PWM clock frequency of 300 MHz and a sample rate of 16 kHz the maximum count is 18,750.
Voltage demand signals for the PWM IP have a full-scale value equal to the maximum count, so setting the voltage demand to the maximum count value achieves 100% duty cycle and 100% of DC link voltage (in this board coming from the simulated power board). Setting the voltage demand to 0 achieves 0% duty cycle and 0% of the DC link voltage. By convention, voltages for display purposes are centred around 0. For example, if the DC link voltage is 48 V voltage demand signals between 0 and maximum count map to 0 to +48 V outputs, but these signals are offset and show in the GUI as -24 V to +24 V.
Using the above example of 300 MHz PWM and 16 kHz sample rate for the Tandem Motion-Power 48 V Board model, in the GUI:
Offset 18,750/2 = 9,375
Scaling 9,375/24 = 391