Brushless DC motors are replacing DC brush motors as power drivers for electric bicycles because of their significant advantages of saving raw materials, reliability, and long service life. Unlike brush motors, brushless DC motors require a position sensor to measure the position of the rotor. The motor controller drives the motor to run continuously by receiving a position sensor signal to synchronize the inverter commutation with the rotor. Although the brushless DC motor can also detect the position of the rotor through the induced electromotive force generated by the stator windings, and the position sensor is omitted, when the motor is started, the rotation speed is too small, and the counter electromotive force signal is too small to be detected, for the electric bicycle. Users inconvenience.
The rotor of a DC brushless motor for an electric bicycle is composed of 30 to 40 pieces of neodymium-iron-boron magnetic steel. Since the surface magnetic field strength of NdFeB magnets exceeds 500 mT, the position sensors in brushless DC motors for electric bicycles are particularly suitable for silicon Hall sensors. Silicon Hall sensor manufacturing process can be fully compatible with the integrated circuit chip process, so that the silicon Hall sensor follow-up signal processing circuit, including the preamplifier, Schmitt trigger and open collector output stage can be easily integrated in On the same wafer, a Hall IC chip is formed.
The Hall sensor chip that can be used as a DC brushless motor position sensor is classified into two types: switch type and lock type. For electric bicycle motors, both Hall sensor chips can be used to accurately measure the rotor magnet position. According to our experimental comparison, the performance of the DC brushless motor prepared with these two Hall sensor chips does not include any difference in the output power, efficiency, and torque of the motor and can be compatible with the same motor controller.
However, this does not mean that motor manufacturers can use commercially available Hall sensor chips. We in the industry may often hear that motor manufacturers due to the improper procurement and use of Hall sensor chip, causing manufacturers to cause huge economic losses, and even lead to bankruptcies. Here we analyze several situations in which the manufacturer uses the motor Hall sensor chip incorrectly:
Brushless DC motors are replacing DC brush motors as power drivers for electric bicycles because of their significant advantages of saving raw materials, reliability, and long service life. Unlike brush motors, brushless DC motors require a position sensor to measure the position of the rotor. The motor controller drives the motor to run continuously by receiving a position sensor signal to synchronize the inverter commutation with the rotor. Although the brushless DC motor can also detect the position of the rotor through the induced electromotive force generated by the stator windings, and the position sensor is omitted, when the motor is started, the rotation speed is too small, and the counter electromotive force signal is too small to be detected, for the electric bicycle. Users inconvenience.
The rotor of a DC brushless motor for an electric bicycle is composed of 30 to 40 pieces of neodymium-iron-boron magnetic steel. Since the surface magnetic field strength of NdFeB magnets exceeds 500 mT, the position sensors in brushless DC motors for electric bicycles are particularly suitable for silicon Hall sensors. Silicon Hall sensor manufacturing process can be fully compatible with the integrated circuit chip process, so that the silicon Hall sensor follow-up signal processing circuit, including the preamplifier, Schmitt trigger and open collector output stage can be easily integrated in On the same wafer, a Hall IC chip is formed.
The Hall sensor chip that can be used as a DC brushless motor position sensor is classified into two types: switch type and lock type. For electric bicycle motors, both Hall sensor chips can be used to accurately measure the rotor magnet position. According to our experimental comparison, the performance of the DC brushless motor prepared with these two Hall sensor chips does not include any difference in the output power, efficiency, and torque of the motor and can be compatible with the same motor controller. However, this does not mean that motor manufacturers can use commercially available Hall sensor chips. We in the industry may often hear that motor manufacturers due to the improper procurement and use of Hall sensor chip, causing manufacturers to cause huge economic losses, and even lead to bankruptcies. Here we analyze several situations in which the manufacturer uses the motor Hall sensor chip incorrectly:
First: manufacturers do not consider the high-temperature characteristics of the motor Hall sensor chip, electric bicycle is working in the field, especially in the summer, the ground temperature may exceed 60 degrees Celsius, coupled with the temperature rise generated inside the motor will exceed 60 degrees, The temperature inside the motor will exceed 120 degrees Celsius. This requires that motor Hall sensor chips for electric bicycles can still operate normally at temperatures above 120 degrees Celsius. We call this circuit in high-temperature integrated circuits. The design and processing of high-temperature integrated circuits is very different from conventional circuits, and the cost is much higher than that of normal-temperature integrated circuits. Many kinds of motor Hall sensor chips that are popular in the market are not high-temperature integrated circuits. Therefore, there is a high probability that summer electric bicycles will fail. This can be seen from the particularly good business of repairing the market in the summer.
Second: Different motor models and different motor design structures require the use of different motor Hall sensor chips. The Hall sensor's magnetic field sensitivity or the starting point of the magnetic field must be matched with the motor model and structure. Different rotor types and different motor design structures have different magnetic field distributions and magnetic field fluctuations. If the Hall sensor's magnetic sensitivity is too high or too low, due to irregular fluctuations in the magnetic field distribution of the rotor magnet and magnetic steel gap, it will cause the position sensor to give an erroneous signal, causing logic chaos in the controller, and the occurrence of motor The phenomenon of large noise, severe vibration, or crashes causes the inverter in the controller to be turned on vertically to burn out the controller and the motor. Therefore, Hall sensor chip manufacturers or distributors must provide satisfactory after-sales service for motor users and match the Hall sensor with the motor to be assembled.
Third: The manufacturer did not consider the anti-static ability of the motor Hall sensor chip. Popular motor Hall sensors are commercially available in two manufacturing processes: Bipolar and CMOS. Motor Hall sensors manufactured with CMOS technology have poor anti-static capability. If there is no special anti-static facility on the motor production line, Hall sensors are vulnerable to electrostatic damage. Usually the damage cannot be detected when the motor leaves the factory, because Hall-effect sensors that are damaged by static electricity still work. However, its lifespan has been greatly reduced. Especially in high temperature or humid environment, Hall sensors exposed to static electricity are particularly prone to failure. As a result, the reversal rate of the motor after delivery is greatly increased, and it will cause huge economic losses to motor manufacturers. . Therefore, motor manufacturers do not purchase hall sensor chips manufactured using CMOS technology. The Hall sensor chip produced by the bipolar process has good anti-static capability and can basically meet the requirements of motor manufacturers without static protection facilities. However, the bipolar process is expensive, and Hall sensor manufacturers in foreign countries have already abandoned the bipolar process and adopted the CMOS process (all foreign assembly workshops have anti-static facilities). The motor manufacturers must use the bipolar manufacturing process to purchase the hall sensor chip.
Fourth: The manufacturer does not consider the anti-surge voltage or anti-surge current capability of the motor Hall sensor chip. Brushless motors for electric bicycles usually operate at high power, and large currents flow through the motor stator windings. Although the Hall sensor chip is electrically isolated from the stator windings, when the current in the winding is rapidly commutated, a large kickback voltage, or surge voltage, is generated. If the freewheel diode of the inverter in the controller cannot effectively suppress the surge voltage pulse (this wave voltage is more harmful to the power MOSFET of the inverter), it is possible to pass power from the controller to the Hall sensor. The input or output causes damage to the Hall sensor and reduces the life of the Hall sensor. The power input or output protection circuit in the Hall sensor chip must have sufficient capacity to withstand surge voltage or inrush current, which increases the cost of the chip.
Fifth: Picking the right Hall sensor chip, manufacturers also need to pay attention to the correct welding of the operating staff, the welding temperature can not be too high, the time can not be too long. The location of the Hall sensor chip should be precise. As the power of the motor increases, the number of magnets used in the rotor increases to more than 50, and the number of slots exceeds 36. Especially for motors with an electrical angle of 60 degrees, a slight deviation in the placement of the Hall sensor chip position will result in the detection of the rotor position. An error in the electrical angle can cause commutation logic to confuse, causing controller and motor damage.
The above lists five categories of motor failures and failures that may be caused by improper selection and use of Hall sensor chips. Hall sensor chips are insignificant in the cost of brushless DC motors for electric bicycles, but they play a crucial role. Motor manufacturers should not buy low-priced products on the market for unknown costs. In order to avoid the above-mentioned problems that may occur, motor manufacturers should select Hall sensor chip suppliers who can provide quality after-sales services. Suppliers who can provide quality after-sales services should have strong technical backgrounds, including microelectronics, integrated circuit design technology, brushless DC motor design and manufacturing technology, etc., so as to provide quality services to motor manufacturers and avoid the above mentioned There are five major issues that may arise. Otherwise, motor manufacturers who purchase and use inappropriate Hall sensor chips may create potential reliability problems, making the life of the motor far less than expected. The most terrible thing is that these problems can not be discerned when the motor is shipped. This will bring enormous operational risks to the motor manufacturers. Once a large area of ​​the motor life cannot be guaranteed, the motor manufacturers will be subject to a huge amount of end-user claims, resulting in direct huge Economic losses were even liquidated.
The rotor of a DC brushless motor for an electric bicycle is composed of 30 to 40 pieces of neodymium-iron-boron magnetic steel. Since the surface magnetic field strength of NdFeB magnets exceeds 500 mT, the position sensors in brushless DC motors for electric bicycles are particularly suitable for silicon Hall sensors. Silicon Hall sensor manufacturing process can be fully compatible with the integrated circuit chip process, so that the silicon Hall sensor follow-up signal processing circuit, including the preamplifier, Schmitt trigger and open collector output stage can be easily integrated in On the same wafer, a Hall IC chip is formed.
The Hall sensor chip that can be used as a DC brushless motor position sensor is classified into two types: switch type and lock type. For electric bicycle motors, both Hall sensor chips can be used to accurately measure the rotor magnet position. According to our experimental comparison, the performance of the DC brushless motor prepared with these two Hall sensor chips does not include any difference in the output power, efficiency, and torque of the motor and can be compatible with the same motor controller.
However, this does not mean that motor manufacturers can use commercially available Hall sensor chips. We in the industry may often hear that motor manufacturers due to the improper procurement and use of Hall sensor chip, causing manufacturers to cause huge economic losses, and even lead to bankruptcies. Here we analyze several situations in which the manufacturer uses the motor Hall sensor chip incorrectly:
Brushless DC motors are replacing DC brush motors as power drivers for electric bicycles because of their significant advantages of saving raw materials, reliability, and long service life. Unlike brush motors, brushless DC motors require a position sensor to measure the position of the rotor. The motor controller drives the motor to run continuously by receiving a position sensor signal to synchronize the inverter commutation with the rotor. Although the brushless DC motor can also detect the position of the rotor through the induced electromotive force generated by the stator windings, and the position sensor is omitted, when the motor is started, the rotation speed is too small, and the counter electromotive force signal is too small to be detected, for the electric bicycle. Users inconvenience.
The rotor of a DC brushless motor for an electric bicycle is composed of 30 to 40 pieces of neodymium-iron-boron magnetic steel. Since the surface magnetic field strength of NdFeB magnets exceeds 500 mT, the position sensors in brushless DC motors for electric bicycles are particularly suitable for silicon Hall sensors. Silicon Hall sensor manufacturing process can be fully compatible with the integrated circuit chip process, so that the silicon Hall sensor follow-up signal processing circuit, including the preamplifier, Schmitt trigger and open collector output stage can be easily integrated in On the same wafer, a Hall IC chip is formed.
The Hall sensor chip that can be used as a DC brushless motor position sensor is classified into two types: switch type and lock type. For electric bicycle motors, both Hall sensor chips can be used to accurately measure the rotor magnet position. According to our experimental comparison, the performance of the DC brushless motor prepared with these two Hall sensor chips does not include any difference in the output power, efficiency, and torque of the motor and can be compatible with the same motor controller. However, this does not mean that motor manufacturers can use commercially available Hall sensor chips. We in the industry may often hear that motor manufacturers due to the improper procurement and use of Hall sensor chip, causing manufacturers to cause huge economic losses, and even lead to bankruptcies. Here we analyze several situations in which the manufacturer uses the motor Hall sensor chip incorrectly:
First: manufacturers do not consider the high-temperature characteristics of the motor Hall sensor chip, electric bicycle is working in the field, especially in the summer, the ground temperature may exceed 60 degrees Celsius, coupled with the temperature rise generated inside the motor will exceed 60 degrees, The temperature inside the motor will exceed 120 degrees Celsius. This requires that motor Hall sensor chips for electric bicycles can still operate normally at temperatures above 120 degrees Celsius. We call this circuit in high-temperature integrated circuits. The design and processing of high-temperature integrated circuits is very different from conventional circuits, and the cost is much higher than that of normal-temperature integrated circuits. Many kinds of motor Hall sensor chips that are popular in the market are not high-temperature integrated circuits. Therefore, there is a high probability that summer electric bicycles will fail. This can be seen from the particularly good business of repairing the market in the summer.
Second: Different motor models and different motor design structures require the use of different motor Hall sensor chips. The Hall sensor's magnetic field sensitivity or the starting point of the magnetic field must be matched with the motor model and structure. Different rotor types and different motor design structures have different magnetic field distributions and magnetic field fluctuations. If the Hall sensor's magnetic sensitivity is too high or too low, due to irregular fluctuations in the magnetic field distribution of the rotor magnet and magnetic steel gap, it will cause the position sensor to give an erroneous signal, causing logic chaos in the controller, and the occurrence of motor The phenomenon of large noise, severe vibration, or crashes causes the inverter in the controller to be turned on vertically to burn out the controller and the motor. Therefore, Hall sensor chip manufacturers or distributors must provide satisfactory after-sales service for motor users and match the Hall sensor with the motor to be assembled.
Third: The manufacturer did not consider the anti-static ability of the motor Hall sensor chip. Popular motor Hall sensors are commercially available in two manufacturing processes: Bipolar and CMOS. Motor Hall sensors manufactured with CMOS technology have poor anti-static capability. If there is no special anti-static facility on the motor production line, Hall sensors are vulnerable to electrostatic damage. Usually the damage cannot be detected when the motor leaves the factory, because Hall-effect sensors that are damaged by static electricity still work. However, its lifespan has been greatly reduced. Especially in high temperature or humid environment, Hall sensors exposed to static electricity are particularly prone to failure. As a result, the reversal rate of the motor after delivery is greatly increased, and it will cause huge economic losses to motor manufacturers. . Therefore, motor manufacturers do not purchase hall sensor chips manufactured using CMOS technology. The Hall sensor chip produced by the bipolar process has good anti-static capability and can basically meet the requirements of motor manufacturers without static protection facilities. However, the bipolar process is expensive, and Hall sensor manufacturers in foreign countries have already abandoned the bipolar process and adopted the CMOS process (all foreign assembly workshops have anti-static facilities). The motor manufacturers must use the bipolar manufacturing process to purchase the hall sensor chip.
Fourth: The manufacturer does not consider the anti-surge voltage or anti-surge current capability of the motor Hall sensor chip. Brushless motors for electric bicycles usually operate at high power, and large currents flow through the motor stator windings. Although the Hall sensor chip is electrically isolated from the stator windings, when the current in the winding is rapidly commutated, a large kickback voltage, or surge voltage, is generated. If the freewheel diode of the inverter in the controller cannot effectively suppress the surge voltage pulse (this wave voltage is more harmful to the power MOSFET of the inverter), it is possible to pass power from the controller to the Hall sensor. The input or output causes damage to the Hall sensor and reduces the life of the Hall sensor. The power input or output protection circuit in the Hall sensor chip must have sufficient capacity to withstand surge voltage or inrush current, which increases the cost of the chip.
Fifth: Picking the right Hall sensor chip, manufacturers also need to pay attention to the correct welding of the operating staff, the welding temperature can not be too high, the time can not be too long. The location of the Hall sensor chip should be precise. As the power of the motor increases, the number of magnets used in the rotor increases to more than 50, and the number of slots exceeds 36. Especially for motors with an electrical angle of 60 degrees, a slight deviation in the placement of the Hall sensor chip position will result in the detection of the rotor position. An error in the electrical angle can cause commutation logic to confuse, causing controller and motor damage.
The above lists five categories of motor failures and failures that may be caused by improper selection and use of Hall sensor chips. Hall sensor chips are insignificant in the cost of brushless DC motors for electric bicycles, but they play a crucial role. Motor manufacturers should not buy low-priced products on the market for unknown costs. In order to avoid the above-mentioned problems that may occur, motor manufacturers should select Hall sensor chip suppliers who can provide quality after-sales services. Suppliers who can provide quality after-sales services should have strong technical backgrounds, including microelectronics, integrated circuit design technology, brushless DC motor design and manufacturing technology, etc., so as to provide quality services to motor manufacturers and avoid the above mentioned There are five major issues that may arise. Otherwise, motor manufacturers who purchase and use inappropriate Hall sensor chips may create potential reliability problems, making the life of the motor far less than expected. The most terrible thing is that these problems can not be discerned when the motor is shipped. This will bring enormous operational risks to the motor manufacturers. Once a large area of ​​the motor life cannot be guaranteed, the motor manufacturers will be subject to a huge amount of end-user claims, resulting in direct huge Economic losses were even liquidated.
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