The controller is regarded as the power source, the motor as the load, the motor as the actuator, and the controller needs to serve the motor. From the perspective of parameters, the phase Angle, current, power, voltage and other parameters of the controller need to meet the requirements of the motor. For example, the power of the controller should be greater than or at least equal to the power of the motor. The controller can be brushless or brushless.
Power, current and other parameters should be matched
At present, dc motors are basically used in the market for electric vehicle power, dc motors are divided into brush and brushless two kinds, if the motor is brush, is mechanical commutation, as long as the highest voltage and maximum current output of the controller, greater than or equal to the rated voltage and rated current of the motor is good.
Brushless motor is electronic commutator, voltage and current parameters are also greater than or equal to the rating of the motor, and hall signal configuration should be considered.
The voltage tolerance of the controller is, of course, higher than the highest voltage of the battery. The nominal voltage of the battery is not the highest voltage. This should be noted.
Motor power size, is dependent on the load and speed requirements of the load, these are not easy to calculate, generally need to be based on some experience value to choose, some occasions also consider the national standard limit of electric bicycle is 400W, the highest voltage is 48 volts.
The greater the power of the motor, the better the power of the car, but the faster the battery consumption, so to increase the capacity of the battery can meet the requirements, the corresponding controller specifications have to rise.
The higher the voltage of the motor, the higher the efficiency of the motor, but the voltage is too high, the insulation requirements of wire and controller are more strict, the battery management is also difficult, very easy to appear safety problems, generally two wheel control in 72 volts is relatively safe. As for those four-wheeled electric vehicles, many of them are of the same industrial level, with dc bus of more than 500 volts and motor voltage of 380 volts, they often need to meet the design standard of IP67, otherwise it is too dangerous to use.
Brushless motor needs to consider the phase Angle
Brushless motor is induced by the hall signal rotor magnetic pole position to the reversing, three hall will output the position of high and low two 01 level, such as 100 is one of the stator and rotor time position, and 000 is another, three hall will have 36 kinds of signal state after permutation and combination, SCM according to these signals to output different pulse voltage to control the motor controller.
In 36 sets of signals, the actual value needs to use the correct two sets, one is forward rotation, the other is reverse rotation. Hall installation time, positive and negative, leads to the so-called 60 degrees and 120 degrees of electricity vector difference, this controller selection, need according to the different angles to choose appropriate, today, of course, there are a lot of controller can oneself learn to judge the phase sequence, but when you buy used, also should pay attention to whether appropriate.
In fact, 60 degrees and 120 degrees, control and use, as long as the software and hardware design in place, will not bring any difference, but because of the production habits and maintenance involved, so there may be differences.
In the early stage, the controller was usually 60°, which was mainly placed in the same direction with three halls, so that it was easy to produce and no errors would be caused. Now, many small factories and low-power products still use 60°.
However, the output signal of 60 degrees has two special Angle signals, 111 and 000. If the motor power is relatively large and the conduction speed is required to be fast, the dead zone on the control may occur and cause the drive damage. So in terms of reliability and safety design, 120° seems to be better, so many factories now use 120°.
Consider economy and reliability
The greater the power of the controller, of course, the better, but if the motor power is relatively small, battery capacity is insufficient, you buy the larger the controller, virtually is a waste, resulting in a big horse car, and electric car pay attention to the lighter the better, the controller is too big may not be a good thing, generally higher than the motor power 20% is about the same.
The controller has overvoltage and undervoltage protection functions, which need to consider the highest and lowest value of the battery voltage to configure, otherwise it may cause the battery has not been discharged to protect, or the battery voltage is too high to cause no output.
Reliability is key, of course, and no one likes to be abandoned halfway. Conditional, of course, to water cooling, there is no condition to consider the installation position, to ensure the rationality of heat dissipation, or add some fans to cool down.
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