JPH01185194A - Step-out detector for synchronous motor - Google Patents

Abstract

PURPOSE:To make an equipment driven by a synchronous motor failsafe, by using the decrease in level of voltage command signal to detect step-out, and by stopping the synchronous motor straightaway. CONSTITUTION:When a synchronous motor 2 is stepped out, then the induced voltage of the synchronous motor 2 is lowered. A voltage command value Vf is lowered along with the lowering of the induced voltage. Accordingly, a relation between input signal Ns and the Vf in a comparator 11 is shown as Ns>Vf, and from the comparator 11, output is generated as step-out detecting signal. This output is stored in a memory circuit 12, and signal is sent to a gate controlling section 8, and output from the gate controlling section 8 is stopped, and the synchronous motor 2 is stopped. Besides, the step-out detecting signal is transmitted to an external section, and a device can be interlocked with an external equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a tax adjustment detection device for a synchronous motor.

B6 Summary of the Invention The present invention provides a control device for operating a synchronous motor using an inverter device, which introduces and compares a rotational speed command signal and an output value of a current control section, that is, a voltage command value, and calculates the result of the comparison. By providing an out-of-step detection circuit that detects the presence or absence of out-of-step based on the synchronized motor, it is possible to quickly detect the adjustment and fail-safe the mechanism driven by the synchronous motor.

C1 Prior Art FIG. 2 shows an open loop control device for controlling a synchronous motor 2 by an inverter device 1. In FIG. 2, the rotation speed command signal Ns generated by the rotation speed command device 3 passes through a voltage control oscillator (VCO) 4 and a sine wave generator 5, becomes a current command value, and is applied to an adder 6. Ru. The adder 6 compares the detected current value of the synchronous motor 2, and the deviation is introduced into the current controller 7.

The output of the current control section 7 becomes a voltage command value Vf and is supplied to the inverter device 1 via the gate control section 8, and the synchronous motor 2 is controlled through the inverter device 1.

D0 Problems to be Solved by the Invention The device shown in Figure 2 is used as a servo device for positioning, etc., but this servo device has a speed variable frequency that is large, and the control system is based on the rotor of a synchronous motor. Since it is an open-loop control in which the position is not detected by a position detector, there is a problem that the synchronous motor may step out.

When a tax adjustment occurs, the synchronous motor must be stopped immediately because control becomes impossible and there is a risk of damage to the drive equipment.

The present invention has been made in view of this point, and its purpose is to easily detect synchronization. It is our intention to provide this type of device.

Means for Solving Problem E1 The present invention has a synchronous motor and an inverter device, obtains a deviation between a current command value based on a rotation speed command signal and a detected current value of the synchronous motor, and uses this deviation value for current control. In a device that controls an inverter device through a section and a gate control section,
The present invention is characterized in that a step-out detection circuit is provided which inputs and compares the rotational speed command signal and the output value of the current control section, and detects the presence or absence of tax adjustment based on the comparison result value.

When step-out occurs in the F9 action synchronous motor, the induced voltage of the synchronous motor decreases, and the voltage command value, which is the output of the current control section, also decreases in proportion to the induced voltage. Therefore, there is a difference between the rotational speed command signal and the rotation speed command signal, and the step-out detection circuit can detect step-out.

G. Embodiment FIG. 1 shows an embodiment of the present invention, and the same reference numerals as in FIG. 2 indicate the same parts. That is, the present invention provides a step-out detection circuit for detecting tax adjustment by inputting and comparing the rotation speed command signal Ns, which is the output of the rotation speed command device 3, and the voltage command Vf, which is the output of the current control section 7. ! 0 is set. This step-out detection circuit IO has a comparator 11 for inputting and comparing signals Ns and Vf, and a memory circuit 12 for storing the output of the comparator 2 and outputting a storage signal. The output of the step-out detection circuit 10 is supplied to the gate control section 8 and is used as another external signal.

The operation of the present invention configured as above will be explained.

The three-phase AC power is converted to DC by a rectifier in the inverter device 1, and then converted to AC again by the inverter and supplied to the synchronous motor 2.

- In the force control device, when the command signal Ns from the rotation speed command device 3 is input to the voltage controlled oscillator 4, this oscillator 4
generates a pulse signal with a frequency corresponding to the signal Ns and applies it to the sine wave generator 5. The sine wave generator 5 outputs a sine wave signal whose frequency is proportional to the frequency of the pulse signal as a current command value, and compares it with the motor current detected in the adder 6 to increase the current in a direction in which the error signal disappears. It is controlled via a control section 7 and a gate control section 8. Further, the signals Ns and Vf are applied to the comparator 11, and the comparison condition in the comparator 11 is set to pJ s <
Vf, and is set so that no output is generated under this condition.

Now, if the synchronous motor 2 loses synchronization for some reason, the induced voltage of the synchronous motor decreases.

When the induced voltage decreases in this way, the voltage command value Vf, which has hitherto been a value commensurate with the induced voltage, decreases as the induced voltage decreases. Therefore, the relationship between the input signal Ns and Vf in the comparator 11 is Ns > Vf, and the comparator 11 generates an output as a tax adjustment detection signal. This output is stored in the memory circuit 12 and also issues a signal to the gate control section 8 to stop the output from the gate control section 8 and stop the synchronous motor 2. Furthermore, this tax adjustment detection signal is also sent to the outside, making it possible to establish an interlock with external equipment.

In the embodiment shown in FIG. 1, the command Ns from the rotation speed command device 3 is displayed as a pattern signal, but when the output Ns of the command device 3 is given as a pulse train, the voltage controlled oscillator 4 This is no longer necessary, and a frequency-voltage converter may be inserted between the rotational speed command device 3 and the tax adjustment detection circuit 10 instead.

H. Effects of the Invention As described above, the present invention utilizes the phenomenon in which the voltage command signal Vf decreases when the synchronous motor steps out, and detects the step-out by comparing this signal Vf and the rotational speed command signal Ns. Because the circuit is simple, the synchronous motor can be stopped immediately by the tax control detection signal, and it is possible to interlock with external equipment, making it possible to control the synchronous motor. It is possible to provide fail-safe equipment for equipment driven by

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional synchronous motor control device. 1... Inverter device, 2... Synchronous motor, 3...
- Rotation speed command unit, 5... Sine wave generator, 7... Current control section, 8... Gate control section,! 0...Out-of-step detection circuit.

Claims (1)

[Claims] (1) It has a synchronous motor and an inverter device, obtains the deviation between the current command value based on the rotation speed command signal and the detected current value of the synchronous motor, and transmits this deviation value to the inverter device via the current control section and the gate control section. A step-out detection circuit is provided which inputs and compares the rotational speed command signal and the output value of the current control section, and detects the presence or absence of step-out based on the comparison result value. Synchronous motor step-out detection device.