Brushless dc motor is composed of main body of the motor and drive, is a typical mechatronics product. Because of brushless dc motor based on self-control type operation, so don't like frequency control of motor speed synchronous motor overload start under plus startup winding on the rotor, also won't generate oscillation and step out when load mutation. Medium and small capacity of the permanent magnet brushless dc motor (BLDCM), now many high rare earth ndfeb magnetic energy product (Nd-Fe-B）Materials. As a result, the volume of rare earth permanent magnet brushless motor than three-phase asynchronous motor with capacity reduces a frame number. Have a motor controller and the connection of the brushless motor controller difference with brush and brushless difference from the power of the motor to distinguish controller is different, there are only two wire brush motor is negative, it is rotor coil so to install carbon brush. It costs little process is relatively simple but power noise. Brushless motor as the three-phase motor magnetic cylinder as the rotor, without carbon brush and hall sensor installation to identify phase, so electrical phase brushless controller has three lines and five hall sensing electric line connected to the motor. At present to solve the hall sensor is easy to damage the machine can't normal use and develop self-learning controller without the connection of hall sensors. But still for three phase line. Has the advantages of brush motor: brush wear and motor noise is a 'brush' relative with brushless the two main disadvantages, but in spite of the two faults, why the vast majority of domestic product version of the factory is still using a brush motor, don't they realize this problem? Here's why: (1)Brush wear does not constitute a major problem: electric bicycle is a kind of intermittent work, communication tools, a set of battery discharge is usually the longest time (Cycling time)As a general rule, be -Hours, the user first day using electric vehicles about - the average amount of timeHours, and now, it is widely used in electric since the dealership disc rotor motor adopts flat type commutator and extended type brush, working life is in commonly hour it is, therefore, according to every user on an average day ride. Hour, the use of a set of brush time has reached its days. It can be seen that a group of qualified brush service time has been nearly three years, and change the brush set of costs for the yuan, a year on average less than yuan! Electric bicycle use the year and determine necessary make a comprehensive inspection and maintenance of vehicles. (2)The motor make a sound is normal, in fact, buy electric cars is not buy air conditioning, consumers don't have to if it has no noise and make the decision to buy or not. In fact, used a brushless motor electric car users will know, brushless motor at light load or low load (Such as flat without wind)The voice of the motor is very small, but when running to important load condition such as uphill, against the wind, it tends to a far more 'huge' sound than a brush motor, appear even uncomfortable electromagnetic shaking, in fact, some vehicle motor running sound is normal, after all, it is a kind of outdoor use of transport, the provisions of the state of the eligibility criteria for less than the db noise, the vast majority of domestic have brush motor can control the decibel value in db below, is a qualified products.
