Accurate current sensing is important
to estimate the rotor angle and speed, and also have the best dynamic motor control.
The current sensing parameters must match the hardware by setting the following
related parameters:
- Dead-band time, the rising edge
delay time must be greater than (high-side turn on time) + (low side turn-off
time) of the power module, and the falling edge delay time must be greater than
(high-side turn-off time) + (low-side turn-on time) of the power module as shown
in the following setting for a power module used in the reference design.
//! \brief Defines the PWM deadband falling edge delay count (system clocks)
#define MTR1_PWM_DBFED_CNT (uint16_t)(2.5f * 120.0f) // 2.5us, (>2.0us)
//! \brief Defines the PWM deadband rising edge delay count (system clocks)
#define MTR1_PWM_DBRED_CNT (uint16_t)(2.5f * 120.0f) // 2.50us, (>2.0us)
- Minimum duration of pulse width
PWM, specifies to be greater than (Hardware delay time + Dead band time +
Ringing duration + ADC sampling time).
//! \brief Defines the minimum duration, Clock Cycle
#define USER_M1_DCLINKSS_MIN_DURATION (450U)
- Sample and hold delay time,
specifies the time delay from PWM output to ADC sample time for current sensing.
The delay time is dependent on the hardware and includes the propagation delay
of the gate driver circuit and turn on and turn off delay of the power FET, and
is less than or equal to (Minimum duration – ADC sampling time).
//! \brief Defines the sample delay, Clock Cycle
#define USER_M1_DCLINKSS_SAMPLE_DELAY (430U)