DRV10983_15 Datasheet, PDF (12/57 Pages) Texas Instruments – DRV10983 12- to 24-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10983
SLVSCP6B – JULY 2014 – REVISED FEBRUARY 2015
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Feature Description (continued)
9.3.2.4 Lock
When the motor is blocked or stopped by an external force, the lock protection is triggered, and the device stops
driving the motor immediately. After the lock release time t_{LOCK_OFF}, the DRV10983 resumes driving the motor
again. If the lock condition is still present, it enters the next lock protection cycle until the lock condition is
removed. With this lock protection, the motor and device does not get overheated or damaged due to the motor
being locked (see Lock Detect and Fault Handling).
During lock condition, the MtrLck Status bit (address 0x10, bit 4) is set. To further diagnose, check the register
FaultCode.
9.3.3 Motor Speed Control
The DRV10983 offers four methods for indirectly controlling the speed of the motor by adjusting the output
voltage amplitude. This can be accomplished by varying the supply voltage (VCC) or by controlling the Speed
Command. The Speed Command can be controlled in one of three ways. The user can set the Speed Command
by adjusting either the PWM input (PWM) or the analog input (Analog) or by writing the Speed Command directly
through the I²C serial port (I²C). The Speed Command is used to determine the PWM duty cycle output
(PWM_DCO) (see Figure 5).
The Speed Command may not always be equal to the PWM_DCO because DRV10983 has implemented the
AVS function (see AVS Function), the acceleration current limit function (see Acceleration Current Limit), and the
closed loop accelerate function (see Closed Loop Accelerate) to optimize the control performance. These
functions can limit the PWM_DCO, which affects the output amplitude.
PWM in
Analog
I²C
PWM duty
ADC
Speed
Command
AVS,
Acceleration Current Limit
Closed Loop Accelerate
PWM_
DCO
Motor
Output
Amplitude
X
VCC
Figure 5. Multiplexing the Speed Command to the Output Amplitude Applied to the Motor
The output voltage amplitude applied to the motor is accomplished through sine wave modulation so that the
phase-to-phase voltage is sinusoidal.
When any phase is measured with respect to ground, the waveform is sinusoidally coupled with third-order
harmonics. This encoding technique permits one phase to be held at ground while the other two phases are
pulse-width modulated. Figure 6 and Figure 7 show the sinusoidal encoding technique used in the DRV10983.
PWM Output
Average Value
Figure 6. PWM Output and the Average Value
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