JPS6111992Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a starting congestion detection device for a synchronous motor that performs self-starting, and in particular, calculates the amount of heat generated in the rotor at the time of starting, and detects starting congestion based on the amount of heat. This makes it suitable for protection during starting congestion.

Conventionally, there has been a starting jam detection device for a synchronous motor that uses a timer and determines that there is a starting jam if the starting is not completed within the time set by the timer. However, the setting time of the above timer is
The time is pre-calculated based on the values of the starting torque generated by the synchronous motor, the reduced voltage starting tap, the resistance torque of the load, etc., and is set with a predetermined margin, so if the load conditions and terminal voltage conditions differ, This has the drawback that the starting times are different and it is difficult to set them. Additionally, since the amount of heat generated in the rotor is greater at the start of startup than at the end of startup, there is a drawback that sufficient protection against startup congestion cannot be provided if the allowable congestion time differs depending on the rotation speed. Ta.

Therefore, this invention was devised to eliminate the drawbacks of the conventional ones as described above.It calculates the amount of heat generated in the rotor at the time of starting, and when the amount of heat exceeds a certain value, outputs a starting congestion detection signal. The present invention provides a starting congestion detection device that can perform highly reliable starting congestion protection.

Hereinafter, one embodiment of the present invention will be explained based on the drawings. In Fig. 1, 1 is a synchronous motor, and the input line of this synchronous motor 1 is connected to a voltage transformer CT and a voltage transformer PT. The armature input P shown in FIG. 2 is detected by the power detector 2 through the CT and PT. When starting the synchronous motor 1, this armature input has a pulsating frequency F=2s
(Here, s is slip, and s is the power supply frequency.) The frequency detector 3 detects the pulsating frequency F, and the average power calculator 4 connected to the power detector 2 calculates the The average power P
₁ is calculated. The pulsating frequency detected by the frequency detector 3 is input to a slip value calculator 5, and a slip value is calculated from the pulsating frequency. On the other hand, the output of the average power calculator 4 is the output of the secondary input calculator 6.
The secondary input calculator 6 calculates the secondary input P ₂ by subtracting the loss of the primary circuit from the average power P ₁ .
is calculated. In this case, the secondary input P ₂ will be proportional to the average power P ₁ as shown in Figure 3, although the loss in the primary circuit will vary depending on the primary current, etc. The value P ₂ can be obtained. Furthermore, the outputs of the slip value calculator 5 and the secondary input calculator 6 are input to a heat amount calculator 7, and the heat amount calculator 7 calculates the amount of heat generated in the rotor. In this case, the amount of heat (secondary loss) P _L generated in the rotor is expressed as P _L = SP ₂ , and by calculating the product of the slip value S and the secondary input P ₂ , the amount of heat generated in the rotor is proportional to the amount of heat generated. You can ask for
By integrating over time, the total loss from the start of the engine to a predetermined rotation point is calculated. The amount of heat calculated by the heat amount calculator 7 is compared with the set value of the discriminator 8. When the amount of heat is greater than the set value, the discriminator 8 operates the output relay 9 and outputs a starting congestion detection signal. be done. The setting value of the discriminator 8 is the amount of heat that the rotor starting winding can tolerate, and can be set arbitrarily. Therefore, according to this embodiment, since the amount of heat generated by the rotor is calculated and starting congestion is detected based on the amount of heat, a highly reliable detection device can be configured, and It is suitable for use in traffic jam protection. Furthermore, according to this embodiment, since the starting congestion detection device is configured based on the detection of armature input, there is no need for detection on the secondary side, and both the brushless excitation method and the brushed static excitation method can be used. Can be applied to synchronous motors.

In addition, in the above example, the secondary input was calculated assuming the primary loss as a constant value, but the secondary input can be calculated by detecting the armature current and terminal voltage and then determining the primary loss. Of course, it is possible to do so.

As described above, according to the present invention, the amount of heat generated in the rotor is calculated, and when the amount of heat exceeds a certain value, the starting congestion detection signal is output, so that the starting congestion detection device has high reliability. can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a starting jam detection device for a synchronous motor according to the present invention, and Fig. 2 shows an armature input P
FIG. ₃ is an explanatory diagram showing the output of each part in FIG. 1. 1: Synchronous motor, 2: Power detector, 3: Frequency detector, 4: Average power calculator, 5: Slip value calculator, 6: Secondary input calculator, 7: Calorific value calculator, 8:
Discriminator, 9: Output relay.

Claims (1)

[Claims for Utility Model Registration] (1) A calculator that calculates the amount of heat generated in the rotor by time-integrating the product of the secondary input of the synchronous motor and the slip value, and the above calculated by this calculator. A starting congestion detection device for a synchronous motor, comprising a discriminator that outputs a starting congestion detection signal when the amount of heat exceeds a certain value. (2) A detector that detects the armature input and its pulsation frequency, and a secondary input calculator that calculates the secondary input by removing the primary circuit loss from the armature input value detected by the detector. , and a slip value calculator for calculating a slip value from the pulsation frequency. The starting congestion detection device for a synchronous motor according to claim 1, which is a registered utility model.