How to choose the EV (electric vehicle) driving motors
The performance
of the drive motor directly determines the performance of the drive system. In
electric vehicles, the selection principles of electric motors are as follers.
(1) High
performance, low weight, and small size;
(2) Higher
efficiency in a wider speed range;
(3) The
electromagnetic radiation is as small as possible;
(4) Low cost.
In addition, the
selection of the motor must also consider the characteristics of its control
system, which can realize two-way control and recover braking regenerative
energy. From the perspective of development trends, traditional DC motors will
lose their competitiveness, and the application of switched reluctance motors
and permanent magnet hybrid motors in electric vehicles has development
potential.
The DC motor
drive system has the advantages of low cost, easy smooth speed regulation,
simple controller, mature technology, etc., and is widely used in electric
vehicles. The disadvantages of DC motors are lower efficiency than asynchronous
motors, large size and mass, inconvenient maintenance of brushes and
commutators, and commutation limits the speed of the motor (the maximum speed
is between 6000r/min and 8000r/min). It is only a three-phase AC motor. Half of
the maximum speed, or even lower.
Compared with DC
motors, asynchronous motors have the characteristics of high efficiency, simple
structure, sturdy, maintenance-free, small size, and light weight, so they have
broad application prospects. However, its control system is more complicated,
the vector control technology requires high frequency conversion speed
regulation, and the cost of using high-power semiconductor devices and
microprocessors is relatively expensive. However, due to its light weight, high
efficiency, and more effective realization of regenerative braking, it is The
operating cost is lower than that of the DC motor drive system.
Switched
reluctance motor is a new type of motor. Its structure is simpler than that of
any kind of motor. Its efficiency can reach 85% to 93%. Its speed can reach
15000r/min. Its torque-speed characteristics are better. Within the range, the
torque and speed can be flexibly controlled, and it has the characteristics of
high starting torque and low starting power, but the torque ripple is large
during operation, the noise is also large, and the volume is larger than the
asynchronous motor of the same power.
As the power
system of the three major parts of electric vehicles, the importance of
electric motors is self-evident. With the development of motor research and
development technology, motors that are more suitable for electric vehicles will
appear in the future. Let's share it again at that time.