Texas Instruments Three Phase BLDC & PMSM Motor Kit with DRV8301 and InstaSPIN-enabled Piccolo TMS320F28069M MCU DRV8301 DRV8301-69M-KIT Datenbogen
Produktcode
DRV8301-69M-KIT
Acceleration (g)
f
RESONANCE
Frequency (Hz)
SLOS825B – DECEMBER 2012 – REVISED JANUARY 2014
APPLICATION INFORMATION
ECCENTRIC ROTATING MASS MOTORS (ERM)
Eccentric Rotating Mass motors, or ERMs, are typically DC-controlled motors of the bar or coin type. ERMs can
be driven in the clockwise direction or counter-clockwise depending on the polarity of voltage across its two
terminals. Bi-directional drive is made possible in a single-supply system by differential outputs that are capable
of sourcing and sinking current. This feature helps eliminate long vibration tails which are undesirable in haptic
feedback systems.
be driven in the clockwise direction or counter-clockwise depending on the polarity of voltage across its two
terminals. Bi-directional drive is made possible in a single-supply system by differential outputs that are capable
of sourcing and sinking current. This feature helps eliminate long vibration tails which are undesirable in haptic
feedback systems.
Figure 14. Motor Spin Direction in ERM Motors
Another common approach to driving DC motors is the concept of overdrive voltage. To overcome the inertia of
the motor's mass, they are often overdriven for a short amount of time before returning to the motor's rated
voltage to sustain the motor's rotation. Overdrive is also used to stop (or brake) a motor quickly. Reference the
motor's datasheet for safe and reliable overdrive voltage and duration.
the motor's mass, they are often overdriven for a short amount of time before returning to the motor's rated
voltage to sustain the motor's rotation. Overdrive is also used to stop (or brake) a motor quickly. Reference the
motor's datasheet for safe and reliable overdrive voltage and duration.
LINEAR RESONANCE ACTUATORS (LRA)
Linear Resonant Actuators, or LRAs, vibrate optimally at their resonant frequency. LRAs have a high-Q
frequency response due to which there is a rapid drop in vibration performance at offsets of 3-5 Hz from the
resonant frequency. Many factors also cause a shift or drift in the resonant frequency of the actuator such as
temperature, aging, the mass of the product to which the LRA is mounted, and in the case of a portable product,
the manner in which it is held. Furthermore, as the actuator is driven to its maximum allowed voltage, many
LRAs will shift several Hz in frequency due to mechanical compression. All of these factors make a real-time
tracking auto-resonant algorithm critical when driving LRA to achieve consistent, optimized performance.
frequency response due to which there is a rapid drop in vibration performance at offsets of 3-5 Hz from the
resonant frequency. Many factors also cause a shift or drift in the resonant frequency of the actuator such as
temperature, aging, the mass of the product to which the LRA is mounted, and in the case of a portable product,
the manner in which it is held. Furthermore, as the actuator is driven to its maximum allowed voltage, many
LRAs will shift several Hz in frequency due to mechanical compression. All of these factors make a real-time
tracking auto-resonant algorithm critical when driving LRA to achieve consistent, optimized performance.
Figure 15. Typical LRA Response
AUTO-RESONANCE ENGINE FOR LRA
The DRV2605 auto resonance engine tracks the resonant frequency of an LRA in real time. If the resonant
frequency shifts in the middle of a waveform for any reason, the engine will track it cycle to cycle. The auto
resonance engine accomplishes this by constantly monitoring the back-EMF of the actuator. Note that the auto
resonance engine is not affected by the auto calibration process, which is only used for level calibration. No
calibration is required for the auto resonance engine.
frequency shifts in the middle of a waveform for any reason, the engine will track it cycle to cycle. The auto
resonance engine accomplishes this by constantly monitoring the back-EMF of the actuator. Note that the auto
resonance engine is not affected by the auto calibration process, which is only used for level calibration. No
calibration is required for the auto resonance engine.
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