Simple questions about DC motors

bigbat

Simple questions about DC motors [Copy link]

When the output power of the DC motor is close to ideal, the higher the voltage, the faster the speed when the load (rated load) is constant, until the motor is magnetically saturated and the motor burns out when the voltage is increased. Conversely, when the load is constant, the lower the voltage, the slower the speed, until it is so low that the motor cannot drag the load (rated load). If the load is too large, will it also burn out?

maychang

There are many types of DC motors, which are differentiated by the way they generate magnetic fields. They include permanent magnet motors, series-excited motors, parallel-excited motors, and series-parallel-excited motors. Some even classify brushless motors as DC motors.

For shunt-excited motors, the higher the voltage applied to the motor, the faster the motor may not necessarily run.

maychang

On the other hand, when the load is constant, the lower the voltage, the slower the speed, until it is so low that the motor cannot drag the load (rated load). If the load is too large, will it burn out?

This is not necessarily the case. The motor burns out because the current is too large. When the voltage across the motor is so low that it cannot pull the load (mechanical load), the current is often very small and it may not burn out.

qwqwqw2088

When the rated voltage is exceeded, the magnetic flux of the motor core will be saturated, and the motor may burn out if the voltage continues to be high.

If the load is too large, the motor may or may not rotate. There will be overload protection, and it will burn out if it is used for a long time.

bigbat

maychang posted on 2022-3-7 10:54 There are many types of DC motors, which are distinguished by the way the magnetic field is generated. There are permanent magnet motors, series-excited motors, parallel-excited motors, and series-parallel-excited motors. There are even brushless motors...

Is this the phenomenon I'm talking about for permanent magnets?

maychang

bigbat posted on 2022-3-7 11:57 Is this the phenomenon I am talking about for permanent magnets?

For permanent magnet motors, when the mechanical load remains unchanged, the higher the applied voltage, the faster the speed, and the lower the applied voltage, the slower the speed.

However, when the voltage is too low to drag the mechanical load, it may not burn out because the current is not large at this time.

maychang

bigbat posted on 2022-3-7 11:57 Is this the phenomenon I am talking about for permanent magnets?

If a permanent magnet motor stalls due to excessive mechanical load at rated voltage, it will almost certainly burn out unless there is a protective circuit.

se7ens

I have a small handheld fan with a DC permanent magnet motor inside.

3 wind speed levels

Motor terminal voltage 5V in gear 1

Motor terminal voltage 7V in gear 2

Motor terminal voltage 9V in gear 3

wangerxian

What experiment is this for???