- What is a Zero Crossing Latch Hall effect IC?
- Zero Crossing Latch Detection principle
- Zero Crossing Latch Hall effect IC capabilities
- Applications for a Zero Crossing Latch Hall effect IC
1.What is a Zero Crossing Latch Hall effect IC?
A Zero Crossing Latch (=Zero Crossing Latch) Hall effect IC is a latch type Hall effect IC that uses a world first detection method to change the output signal at the zero-crossing point where polarity changes. Optimized for brushless DC (BLDC) motors, this Hall effect IC is not thrown off by changes in magnetic flux density and therefore provides stable detection.
Zero Crossing Latch Hall effect ICs can easily prevent drops in motor efficiency resulting from temperature variations and manufacturing variations.
2.Zero Crossing Latch Detection principle
A conventional Hall effect IC detects the polarity and intensity of the applied magnetic flux density and switches the output signal. (For details, refer to “What is a Hall effect IC?”)
In contrast a Zero Crossing Latch Hall effect IC detects when the S-pole of the applied magnetic flux density changes to N-pole or vice versa, that is when there is a polarity change and switches the output signal.
3. What Zero Crossing Latch Hall effect IC can
A Zero Crossing Latch Hall effect IC provides BLDC motor control with the following three advantages.*1
①Prevents a reduction in efficiency due to temperature changes
②Prevents a reduction in efficiency due to manufacturing variations
③Simplifies the control software required for smooth high-speed revolution
① Prevents a reduction in efficiency due to temperature changes
The ambient temperature of a Hall effect ICs used as a position sensor in a BLDC motor changes significantly with the environment and load fluctuations. Especially, as motor load increases, the coil generates heat that raises the temperature of the magnet resulting in a change of the magnetic flux density that affects the Hall effect IC.
In a Hall effect IC using the conventional method of detection, the change in the magnetic flux density caused by the temperature rise in the magnet means that the signal misses the optimal timing for output leading to a vicious circle of lowered motor efficiency and further rises in temperature.
Unlike conventional Hall effect ICs, a Zero Crossing Latch Hall effect IC senses when polarity changes and is capable of optimal timing output even if magnet characteristics change as temperature rises. This prevents the successive reduction of efficiency that occurs when a Hall effect IC misses the optimal timing for output.
② Prevents a reduction in efficiency due to manufacturing variations
For a variety of reasons, the distance between the rotor of the BLDC motor and a Hall effect IC is often not uniform.
The machining accuracy of the rotor, the assembly accuracy of the rotation axis, bearings, rotor and other parts, the accuracy of mounting components on the sensor PCB and other factors during manufacture in addition to vibrations during motor rotation may also cause the distance between the magnet and sensor to vary.
For these reasons, mass produced motors that had been expected to provide satisfactory efficiency at the design stage may exhibit individual variations in efficiency leading to variations in efficiency also during operation.
A Zero Crossing Latch Hall effect IC, on the other hand, senses when polarity changes and outputs a signal at the right time regardless of variations in the distance between the magnet and the sensor and prevents reductions in efficiency due to any manufacturing variations.
③ Simplifies the control software required for smooth high-speed revolution
Accurate rotational angle sensing is indispensable to each motor to ensure smooth high-speed rotation.
This requires integrating advance angle and delay angle control into the legacy motor control software, providing a temperature-based timing table, making calibrations to adjust for and absorb manufacturing variations.
However, if the factors that change magnetic flex density are used for detecting motor rotation, the software will need to perform more granular control to check a greater number of conditions.
Since a Zero Crossing Latch Hall effect IC can detect a polarity change regardless of external causes, there is no need to perform calibration to account for changes in magnetic flux density. This means simpler software can be used to provide smooth rotation control without calibration.
The Zero Crossing Latch Hall effect IC is the next generation Hall effect IC that will not only improve motor efficiency but also reduce design man-hours.
*1…The degree of effect varies depending on the motor structure and control method.
4. Applications for a Zero Crossing Latch Hall effect IC
For customers who are considering use of a Hall effect IC for motor control or who are already using a Hall effect IC, the following introduces cases where a Zero Crossing Latch Hall effect IC is the recommended solution.
In the following cases, a Zero Crossing Latch Hall effect IC can easily provide an ideal motor.
- When the motor is small and rotor magnetic flux is weak
- When an optional magnet provided for motor sensor detection is to be removed to simplify configuration
- To substitute an SMD motor sensor for a SIP sensor
In the following cases, a current bipolar Hall effect latch IC can provide sufficiently stable control.
- When magnetic flux acting on the motor sensor is adequately strong, control will not be affected by minor changes in magnetic flux.
- When the motor sensor signal is used only to determine the start position and to confirm rotation and control does not rely on the sensor signal.
If you are lokking for hall effect IC, ABLIC’s Hall effect ICs come highly recomnmended.
Our Hall effect ICs with high-volt and high-speed are suitable to BLDC motor control.
Our “magnetic simulation service” provides you the ideal combination of magnets and Hall effect ICs
ABLIC Inc. offers a “magnetic simulation service” that provides the ideal combination of magnets and our Hall effect ICs for customer systems. Our magnetic simulation service will reduce prototype production, development period and development costs. In addition, it will contribute to optimization of parts to realize high cost performance.
For more information regarding our magnetic simulation service, contact our sales representatives.