Several new features are included in version 4 of the development box. Most notably is the built-in ability to measure the DC supply current to the motor driver.
As the motor is operating in resonance at approximately 40kHz and is driven by a two-phase drive voltage of more than 100Vrms, it is highly desirable to have a simple way of monitoring the motor operation without measuring the drive current itself.
The DC current supplied to the motor driver is closely correlated to the motor performance (resonance, speed & stall momentum) and is convenient to measure during operation as well as for production testing.
The panel above for the control SW shows the new features:
- DC current readout: Continuous monitoring of current
- Results from frequency sweep: Current at the resonance peak
- Track frequency: Compensate for temperature drift
The motor resonance frequency is mostly determined by mechanical constants of the PCB-material and it is necessary to compensate for the change in resonance frequency for the best performance over temperature. For continuous operation the new tracking feature in version 4 is an effective way of setting the optimum frequency to compensate for the self-heating in the motor.