ProductsThe production site control and standardized assembly line are designed according to European standards. The products are divided into 8 series and 115 models.
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About UsFounded in June 2004, Comps Compressor Co., Ltd. is a high-tech enterprise integrating R&D, manufacturing and marketing, and enjoys a high reputation in the industry.
ApplicationThe service system of Comps company spreads all over the country, we have the strongest technical force and can make the fastest response to the actual needs of users.
What are the manifestations and causes of loss of excitation of permanent magnet motor?
1) Loss of excitation judgment: after the loss of excitation of permanent magnet motor, the most direct and accurate judgment is that the measured motor back emf will decrease a lot (for example, the normal back emf will be normal 350V, and it will drop below 300V after loss of excitation. The size of the back EMF is determined according to the size of loss of excitation). It can also be judged according to the input voltage in the display screen. The input voltage value will decrease after loss of excitation (generally about 20V lower than the standard). Due to the large current after loss of excitation, if the frequency converter is equipped with self-protection, it will reduce the frequency.
2) Reasons for loss of excitation: the first is high temperature. The permanent magnet of the motor is most afraid of high temperature. If there is a high temperature above 150 ℃, there may be loss of excitation. 130 ℃ protection PTC is installed in the permanent magnet motor package of our company, which can avoid loss of excitation at high temperature. Another reason is that if the carrier frequency of the frequency converter is very low, it will also cause poor sine wave waveform, resulting in the negative value of ID current becoming larger, resulting in loss of excitation. At this time, it shows the above loss of excitation, and the motor noise and vibration increase.
3) Treatment method: first, prevent high temperature. When setting the carrier frequency, according to experience, a sine wave needs at least 20 points of control, so the setting of carrier frequency = 20 × Operating frequency. For example, the carrier frequency of the maximum 200Hz unit shall be set at least 20 × 200=4000Hz。 The carrier frequency should not be too high. If it is too high, the frequency converter will have IGBT heating and shutdown. The standards of each manufacturer are different. Generally, the temperature limit of the module is set to 85 ℃. When setting, ask the frequency converter manufacturer for reference.
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