Motor Explanation/motor Rotation

Motor explanation/motor rotation

1.Principle

 

Resolver is a position sensor commonly used in motor control, the role of resolver is to accurately measure the position, speed and rotation direction of the motor rotor, transmit these signals to the electronic control, and control the motor by the control algorithm of the software.

 

It can control the frequency and sequence of three-phase alternating current, so that the speed and steering (forward and reverse) of the drive motor can be changed. When the permanent magnet synchronous motor is working, the rotating magnetic field generated by the stator coil rotates synchronously with the rotor, and the rotating magnetic field pole and the rotor pole will maintain a certain angle, and the rotational change is the rotation that monitors the position and speed of the rotor.

 

The principle of rotating: by entering a high-frequency sinusoidal signal to the rotor coil, that is, we often call the excitation signal (the power supply of the resolver), then we can receive the high-frequency induction signal fed back by the induced rotor in the coil, and the corresponding sine and cosine information can be obtained after processing, and the absolute position of the stator can be obtained after software analysis.

 

2.Calibration

 

There are many popular sayings in the calibration of rotary transformation in daily work, such as zero angle calibration, motor angle calibration and so on. Although the statements are different, the content and function are the same, that is, to know the angular deviation between the zero position of the rotation and the zero position of the motor.

 

3. Common failures

If there is a problem with the rotation, then there is bound to be a problem in terms of rotational speed.

1. Under the static condition of the vehicle (the actual motor speed is zero), the instrument falsely alarms that the motor has a speed;

2. Under high voltage normal conditions, the gear pedal motor has no output speed;

3. Cause three-phase hardware overcurrent fault;

4. Cause IGBT failure;

5. Cause motor speed jitter:

6. Cause motor stall;

7. Vibration, abnormal noise；

A new fault caused by the wrong sequence of the rotating harness: a motor passed the detection of the software and hardware version of the controller, and the NVH working condition appeared to click and abnormal noise, the characteristic curve was abnormal, the speed was negative, and finally the design error of the resolver harness was found.

Pass the electrical detection amount

There are generally 6 rotary lines connected to the motor end from the motor controller end, namely: ref± (excitation signal), sin± (sinusoidal signal) and cos± (cosine signal), each group of signals is a chord signal) and cos± (cosine signal), each group of signals has its own corresponding negative value, you can determine whether it is a rotulation fault by measuring the three sets of rotational resistance values at the motor control plug-in end or the motor end。

2) Characteristic curve

Motor speed is a companion signal of motor torque, just like a gear, you want the gear to turn, then an external force is required.

The normal motor speed changes smoothly and linearly.

Smooth and rounded, silky smooth

Abnormality: The motor speed curve displayed under a rotator fault looks like a burr. During the driving process of the vehicle, because of the jitter of the motor speed, it will cause the driving shaking of the whole vehicle。

 

Rotary harness, one end is connected to the low-voltage plug-in of the motor controller, and the other end is connected to the low-voltage plug-in of the motor, we have the following diagnostic means:

 

1) Unplug the low-voltage plug-in at the motor controller end and the resolve-variable low-voltage plug-in at the motor end, and use a multimeter to measure the on-off of excitation (ref±), sine (sin±) and cosine (cos±);

 

2) If the measurement of the negative value of the rotation is normal, but can not judge whether the wiring harness and plug-in virtual connection problem, you can install the low-voltage plug-in at both ends, grab the wiring harness and shake it vigorously, if the speed of the instrument fluctuates abnormally, it is still necessary to carefully check the wiring harness and low-voltage plug-in;

 

3) If the measured resolver resistance value is normal (from the low-voltage plug-in end of the motor controller and the motor end), and it is confirmed that the wiring harness and plug-in are normal, the motor controller needs to be replaced.