DRV10964 Datasheet, PDF (8/27 Pages) Texas Instruments – Three-Phase Sinusoidal Sensorless BLDC Motor Driver

DRV10964
SLDS227 – MARCH 2016
www.ti.com
Feature Description (continued)
When the PWM commanded duty cycle input is driven to 0% (less than VIL_PWM for at least t_SLEEP time), the
DRV10964 device will enter a low power sleep mode. In sleep mode, most of the circuitry in the device will be
disabled to minimize the system current. The current consumption in this state is specified by I_{VCC_SLEEP}.
The device will remain in sleep mode until either the PWM commanded duty cycle input is driven to a logic high
(higher than V_{IH_PWM}) or the PWM input pin is allowed to float. If the input is allowed to float an internal pullup
resistor will raise the voltage to a logic high level.
Recovering from sleep mode is treated the same as power on condition as illustrated in Figure 14.
As part of the device initialization the motor resistance value and the motor Kt value are measured during the
initial motor spin up as shown in Figure 14.
7.3.2 Speed Input and Control
The DRV10964 provides three-phase 25-kHz PWM outputs which have an average value of sinusoidal
waveforms from phase to phase. When any phase is measured with reference to ground, the waveform observed
will be a PWM encoded sinusoid coupled with third order harmonics as shown in Figure 2. This encoding
scheme simplifies the driver requirements because there will always be one phase output that is equal to zero.
U-V
U
V-W
V
W-U
W
Sinusoidal Voltage from Phase to Phase Sinusoidal Voltage from Phase to GND
With Third Order Harmonics
PWM Output
Average Value
PWM Encoded Phase Output and the Average Value
Figure 2. Sinusoidal Phase Encoding Used in DRV10964
The output amplitude is determined by the supply voltage (VCC) and the commanded PWM duty cycle (PWM) as
described in Equation 1 and illustrated in Figure 3. The maximum amplitude is applied when the commanded
PWM duty cycle is 100%.
Vph_pk = PWMdc × VCC
(1)
100% output
VCC
Vph_pk
VCC*PWMdc
Figure 3. Output Voltage Amplitude Adjustment
The motor speed is controlled indirectly by using the PWM command to control the amplitude of the phase
voltages which are applied to the motor.
8
Submit Documentation Feedback
Product Folder Links: DRV10964
Copyright © 2016, Texas Instruments Incorporated