Brushless DC motor as saving raw materials, good reliability, long life and other significant advantages, are replacing DC brush motors for use as electric powered bicycle. With different brush motors, brushless DC motors require position sensors to measure the rotor position. By accepting the position sensor motor controller signal to make the conversion phase power inverter
to drive the motor rotor synchronous continuous operation. Although the brushless DC motor can also be generated by the stator windings to detect the rotor electromotive force offensive position, and eliminating the need for the position sensor, but the motor starts, the speed is too small, offensive-electromotive force detection signal is too small, the electric bicycle users great inconvenience.
Electric bicycle brushless DC motor rotor is 30-40 NdFeB magnets composition. Since NdFeB magnet surface magnetic field strength of more than 500 mT, electric bicycle brushless DC motor in the position sensor is especially suitable for silicon Hall sensor. Hall sensor silicon manufacturing process may be compatible with the integrated circuit chip process, so that the subsequent silicon Hall sensor signal processing circuit, including the pre-amplifier, Schmitt trigger and open collector output stage can be easily integrated in the same silicon is formed on the Hall IC chip.
Can be used as a brushless DC motor position sensor Hall sensor chip is divided into two kinds of switching and locking. The electric bicycle motor, the two Hall sensor chip can be used to accurately measure the position of the rotor magnet. According to the experimental comparison, the two Hall sensor chip preparation brushless DC motor performance, including motor output power, efficiency and torque, etc. there is no difference, and can be compatible with the same motor controller.
However, this does not mean that you can not use the motor manufacturers market motor Hall sensor chip. Insiders may often hear the motor manufacturers because the procurement and use of improper Hall sensor chip, resulting in huge economic losses caused by manufacturers, and even lead to bankruptcy. To analyze the following manufacturers use motor Hall sensor chip incorrect situations:
1: manufacturers do not consider the motor Hall sensor chip temperature characteristics, the electric bike is working in the field, especially in the summer, the surface temperature may exceed 60 ° C plus temperatures generated inside the motor will be more than 60 degrees, internal motor temperature will exceed 120 degrees Celsius. This is required for electric bicycle motor Hall sensor chip at temperatures over 120 degrees Celsius can still work, we call this chip in the circuit is a high-temperature integrated circuits. Temperature IC design and manufacturing with the conventional circuit is very different, the cost is much higher than the ordinary integrated circuits. The popularity of many kinds of motor Hall sensor integrated circuit chip is not high, so the summer bike large probability of failure, which is, from the aftermarket business in the summer can be seen particularly well.
Second: the different motor types and different motor design structure, we need a different motor Hall sensor chip, mainly the magnetic field sensitivity of the Hall sensor or a magnetic field, said the opening starting with the motor type and structure of the match. Different motor models and different rotor motor design structures with different magnetic field distribution and the magnetic field distribution fluctuations. If the Hall sensor magnetic sensitivity is too high or too low, since the rotor magnet and the magnet gap magnetic field distribution of the irregular fluctuations will lead position sensor gives the wrong signal, causing the controller has logical confusion, ranging appeared motor noise, vibration, or crashes and so powerful, heavy lead to the controller power inverter with charger
conduction occurs vertically and burned controllers and motors. Therefore, the Hall sensor chip manufacturer or distributor to the motor users with good service, so Hall sensor to be fitted with a motor to match.
Third: The manufacturers do not consider the motor Hall sensor chip antistatic ability. The popularity of the motor Hall sensor chip manufacturing process consists of two processing production: Bipolar and CMOS process technology. Using CMOS technology motor Hall sensor chip antistatic ability is poor, if the motor production line no special anti-static facilities, Hall sensors are susceptible to electrostatic damage, this damage is usually shipped in the motor can not be detected, because it was by electrostatic damage Hall sensor is still able to work. However, its life has been greatly reduced, especially in hot or humid environment by electrostatic damage Hall sensors are particularly vulnerable to failure, resulting in motor factory after the anti-revisionist rate greatly increased, will give the motor manufacturers to bring huge economic losses . Therefore, the motor manufacturers do not use CMOS technology procurement Hall sensor chip. With bipolar technology, the motor Hall sensor chip antistatic ability is better able to meet the basic static-protective equipment motor manufacturer's requirements. However, bipolar process expensive abroad Hall sensor manufacturers have given up on bipolar process and the use of CMOS technology (foreign machine assembly plant has anti-static facilities). Motor manufacturers in the procurement of a Hall sensor chip must determine the chip processing technology is the use of bipolar manufacturing process.
Fourth: The manufacturers do not consider the motor Hall sensor chip surge voltage or surge current capability. Electric bicycle brushless motors are usually used in high power work, the motor stator windings flows through a large current. Although the hall sensor chip and the stator windings are electrically completely separated, but when the current in the winding commutation rapid, large kickback voltage is generated or so-called surge voltage. If the controller inverter wheeling diodes can not effectively suppress the surge voltage pulse (this wave with a voltage of the inverter power FET harm even more), it is possible to pass through the controller Hall sensor supply the input or output side, resulting in damage Hall sensor, reducing the life of the Hall sensor. Hall sensor chip in the power input or output of the protection circuit should have sufficient capacity to resist the surge voltage or surge current, which will increase the cost of the chip.
- 2013/08/28(水) 09:03:34|