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The brushless DC motor and control module certification

Date:2013-12-25 8:39:41 Hits:
Series excitation type motor performance and Application
Series excitation type motor is also called the brush type motor, which has characteristics of high torque output, often used in no power tools accurate speed control, such as a portable electric drills, circular saws or desktop wood sawing machines, woodworking angle cutting sawing machine etc.. The use of mechanical commutation in the structure, the power supply to the motor rotor winding. Due to the adoption of contacting mechanical structure of supply power to the motor rotor winding, so the industry often also will change the power supply contactor is called "brush", commonly used brush with graphite or copper foil as material.
Rotor friction term and brush motor, can cause considerable noise, vibration, electromagnetic interference (EMI) and arc, conductive material powder and wear can be filled with the motor, causing some degree of electrical pollution. Therefore, in terms of product safety, reliability, or from the maintenance cost point of view, are the need for in-depth consideration. While the motor speed and torque control is more complex, and generally require the use of external angle encoder or speed generator to detect motor running data. In addition, the rotation of the winding cannot install the temperature protection switch or a temperature fuse, insulating material must therefore rely on each site tests (e.g., line shaft groove, phase converter...) To assess the risk of electric shock and fire will.
The application and principle of the brushless DC motor
Brushless DC motor (BLDC) is the use of electronic commutation circuit of the DC power supply to the motor rotor winding, because there is no brush mechanical, so called brushless DC motor. Because the control performance of Brushless DC motors with high efficiency, accurate, and can be packaged to meet safety requirements and characteristics of the use of electronic, in the global energy, carbon reduction under the demands of the current, widely used in refrigeration and air conditioning field, such as the DC conversion, common brushless DC technique, it can also be used in the hybrid electric vehicle and some high economic value of household electrical appliances such as electric fan and other products.
At present, the most common way of electronic drive, is the use of Holzer effect component or mechanical point of back EMF Detection of motor rotor winding and the motor angle, and then switch to control the MOSFET accurately, in order to achieve the sustainable operation of motor.
In the Holzer assembly as an example, the Holzer effect to satisfy the following relations:
Where VH is the Holzer IH Holzer current, voltage, KH/d for the Holzer assembly of electromagnetic coefficient, K for the Holzer assembly unbalance coefficient of magnetic flux density, B. The relationship can be understood, Holzer voltage and flux density (the strength of the magnetic field is also the motor running) and Holzer current is proportional to, therefore, when different magnetic and Holzer assembly rotor shaft, the flux is smaller. In order to maintain the Holzer fixed voltage, you must increase the Holzer current, so that it can calculate the accurate rotor motor conduction sequence and time.
Characteristics of Brushless DC motor
The Holzer assembly type brushless DC motor due to the use of Holzer components to induction excitation sequence and time, the rotor phase π /2 can make stator conduction, thus can reduce the unnecessary electric energy waste, but also can provide timely rotor electromagnetic force required for rotation, a lifting motor output torque and efficiency the biggest advantage, which is all the brushless DC motor can provide
In the brushless DC motor in hardware, electronic circuit replaces mechanical commutator and brush, no electrical pollution. At the same time, the electrical signal to the electronic circuit are captured, you can compare amplification, signal with other logic circuits, and the motor running efficiency.
More importantly, the original can not be applied to protect the motor and hardware protection device to solve the problem, on the brushless DC motor can use microprocessors and software, electrical signal to determine the electronic circuit are captured, and the motor stall, phase lack, over load, and other related and safety function management and protection.
In contrast, for the brushless DC motor with electronic protection function, due to the acquisition and processing electrical signal using a lot of electronic equipment, so must accept the electromagnetic compatibility evaluation; as for the reliability of software, consideration should be given to the risks associated with, and to the management and protection of the software, also must be assessed.
The control module certification
UL1004 motor safety standard contains the specification for electronic protection type motor, the UL product category number is XDNW. Clear the standard requirements of section 18B, where has the electronic protection controller of motor, such as business or home use, the controller must comply with the UL60730-1A standard; if the electronic protection controller of motor has will only be used in industrial applications, the controller must conform to the UL508 standard. The application range of the UL60730-1 standard for household (also contains similar purposes, such as commercial use) controller of electrical products, this is the safety specification of a and IEC 60730-1A merger, in the appendix H provides the relevant safety standards for electronic controller, and contains software and electromagnetic compatibility.
UL60730-1A controller in accordance with the purposes, divided into running applications and protection uses two categories. As the name implies, refers to the use of the controller operates under normal operating conditions, the device controller activation, operation, such as mechanical type single-phase AC motor activation switch, belonging to the running application controller. Use and protection controller, refers to when the device is in the non normal operating conditions, extraction
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