JPH05268721A - Missing phase detection circuit of ac servo device - Google Patents

Abstract

PURPOSE:To recognize an abnormal state of a motor to output a missing phase detection signal (an abnormal generating signal) when an electric current supplied to a trapezoid wave driving synchronous AC servo-motor is not in a state of a three phase trapezoid wave and to trip a servo device before the abnormal rotating operation of the motor, for example, based on the missing phase detection signal. CONSTITUTION:Current detection signals iu, iv and iw for actual three phase sequence component of an AC servo-motor obtained from a three phase current detection circuit 8 are added in an operation circuit 10, and when summing absolute value through an absolute value circuit 11 of a missing phase detection signal generation circuit 100 is in excess of specific threshold value in a missing phase signal output circuit 12, a missing phase detection signal as abnormal supply of a three phase current to the AC servo-motor is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open phase detection circuit for an AC servo device using a synchronous AC motor driven by a three-phase trapezoidal wave.

[0002]

2. Description of the Related Art FIG. 3 shows a current control circuit of a conventional trapezoidal wave drive synchronous AC servo device.

In FIG. 3, the three-phase current command circuit 1 has a three-phase trapezoidal current command signal i for a desired torque value so that the trapezoidal wave drive synchronous AC servomotor 9 generates a desired torque. Generate ^* _u , i ^* _v , i ^* _w .

The subtraction circuit 2 outputs the current command signal and the three-phase current detection signals i _u and i output from the three-phase current detection circuit 8.
_v, enter the i _w, subtracted for each phase ^{_{(i * u -i u, i}} *
^{_{v -i v, i * w -i}} w) is carried out for deviation signal ε _iu of the current of each phase, ε _iv, to output a ε _iw.

The three-phase current control circuit 3 inputs the deviation signals ε _iu , ε _iv , ε _iw of the currents of the respective phases, performs PI calculation for each phase, and outputs a voltage command signal v ^* _{u for} three phases. , V ^* _v , v ^* _w
Is output.

[0006] PWM control circuit 4, the three phases of the voltage command ^{_{v * u, v * v,}} v * w type a and PWM voltage signal for three phases corresponding to the command value v _{u, v} v, Output v _w .

The DC power source 5 is a DC power source for the PWM inverter, and the PWM inverter 6 is the PWM voltage signal v.
_u , v _v , v _w are input to supply a three-phase AC voltage to the trapezoidal wave drive synchronous AC servo motor 9.

Reference numeral 7 denotes a current sensor for detecting currents for three phases. A three-phase current detection circuit 8 inputs the output of the current sensor and outputs an actual current detection signal for three phases. Input to the subtraction circuit 2.

[0009]

However, the current control circuit of such a trapezoidal wave drive synchronous AC servo device is premised on that a trapezoidal wave current flows in the trapezoidal wave drive synchronous AC servo motor. If the phenomenon in which the current for one phase does not flow for some reason, or the trapezoidal wave current does not flow in each phase, the trapezoidal wave drive synchronous AC servo motor produces a torque corresponding to the regular torque command. There was a problem that a state such as rotating or stopping without generating occurred.

Therefore, the object of the present invention is to detect an abnormal condition for the electric motor when the current flowing through the trapezoidal wave drive synchronous AC servomotor is not a three-phase trapezoidal wave, and detect a phase loss detection signal ( It outputs an error occurrence signal) and tries to trip the servo device.

[0011]

That is, an open phase detection circuit of an AC servo device according to the present invention detects a current of each phase of a trapezoidal wave drive synchronous AC servo motor to be controlled,
A three-phase current detection circuit that outputs a three-phase current detection signal, and by inputting the three-phase current detection signals and adding the respective signals, the added value of the currents for the three phases is obtained, and the open-phase detection is performed based on that value. And a phase loss detection signal generating circuit for outputting a signal.

[0012]

That is, the added value of the three-phase current detection signal is "0" in the normal state, and when the added value shows an abnormal value, it is detected that an abnormality such as a missing phase has occurred in the three-phase current. ..

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the construction of an open phase detection circuit of a trapezoidal wave drive synchronous AC servo device. In FIG. 1, reference numeral 8 is a current sensor similar to the three-phase current detection circuit 8 in FIG. The output of 7 is input and the actual current detection signals _iu , _iv , and _iw for three phases are output. Arithmetic circuit 10
The actual current detection signal i _u of the three phases, i _v, i _w
By inputting and adding each, the added value of the current for three phases is output.

The phase loss detection signal generation circuit 100 comprises an absolute value circuit 11 and a phase loss signal output circuit 12. The absolute value circuit 11 inputs the added value, takes its absolute value and outputs an absolute value signal. To do.

The open-phase signal output circuit 12 inputs the absolute value signal, and when the value exceeds the threshold value δ, outputs the open-phase detection signal as the open-phase condition has occurred. Then, this signal causes the power supply to be supplied to the electric motor (AC servomotor) 9 to trip because it is determined that the phase-shifted state (abnormal state) has occurred in the trapezoidal wave drive synchronous AC servomotor. The theory underlying the present invention will now be described.

In an AC servo apparatus using a synchronous AC servomotor 9 driven by a three-phase trapezoidal wave, the current flowing through the motor 9 is premised on a trapezoidal wave for each phase, and if this collapses, the desired torque is not generated. Problems such as occur. However, assuming that the three-phase trapezoidal wave current is flowing normally now, as shown in FIG. 2, the added value Σi of the current of each phase is Σ
i = _iu + _iv + _iw = 0.

Therefore, the present invention utilizes this property to add the current detection signals i _u , _iv , and i _w for the actual three phases, and when the absolute value of the added value does not exceed a certain threshold value δ. Is considered to be operating normally, and if the threshold value δ is exceeded, it is determined that an open phase condition has occurred, an abnormality occurrence signal is output, and the servo device is tripped.

That is, in the trapezoidal wave drive synchronous AC servo device, if a current for one phase of the AC servomotor 9 does not flow, or a trapezoidal current does not flow in each phase, a phenomenon occurs. If there is, the three-phase current detection signals i added in the arithmetic circuit 10
_u, the sum of i _v, i _w is an abnormal value, given the open phase signal output circuit 12 through the absolute value circuit 11 for phase loss detection signal generation circuit 100, the absolute value of the addition exceeds a predetermined threshold value δ Then, the open phase detection signal is output.

That is, assuming that a phase loss state (abnormal state) has occurred in the trapezoidal wave drive synchronous AC servo motor upon receiving the output of this phase loss detection signal, for example, the power supply to the electric motor (AC servo motor) 9 is supplied. By causing the motor 9 to trip, the servo device can be tripped assuming that an abnormal state has occurred before the problem that the motor 9 rotates or stops without generating the torque corresponding to the regular torque command.

Therefore, according to the open-phase detection circuit of the trapezoidal wave drive synchronous AC servo device having the above-mentioned configuration, the current detection signals i _{u for} the actual three phases of the AC servomotor obtained from the three-phase current detection circuit 8 are obtained. When i _v and i _w are added in the arithmetic circuit 10 and the added absolute value passed through the absolute value circuit 11 of the open phase detection signal generation circuit 100 exceeds the predetermined threshold δ in the open phase signal output circuit 12, Since the configuration is such that the open phase detection signal is output as an abnormal supply of the three-phase current to the AC servo motor, for example, by stopping the power supply to the AC servo motor upon receiving the open phase detection signal, the motor rotates abnormally. It can be prevented from operating.

[0022]

As described above, according to the present invention, a three-phase current detection circuit that detects the current of each phase of a trapezoidal wave drive synchronous AC servomotor to be controlled and outputs a three-phase current detection signal is provided. A phase loss detection signal generation circuit for inputting the three-phase current detection signals and adding the respective signals to obtain an added value of currents for three phases and outputting a phase loss detection signal based on the added value. Since it is configured, when the current flowing through the trapezoidal wave drive synchronous AC servomotor is not a three-phase trapezoidal wave, the motor can recognize that it is in an abnormal state and output the open phase detection signal (abnormality occurrence signal). Based on this open phase detection signal, the servo device can be tripped before the abnormal motor rotation operation.

[Brief description of drawings]

FIG. 1 is a trapezoidal wave drive synchronous AC according to an embodiment of the present invention.
The block diagram which shows the structure of the open phase detection circuit of a servo apparatus.

FIG. 2 is a diagram showing an addition state when a three-phase current is normal in the arithmetic circuit of the open phase detection circuit.

FIG. 3 is a block diagram showing the configuration of a current control circuit of a conventional trapezoidal wave drive synchronous AC servo device.

[Explanation of symbols]

1 ... Three-phase current command circuit, 2 ... Subtraction circuit, 3 ... Three-phase current control circuit, 4 ... PWM control circuit, 5 ... DC power supply, 6 ... PW
M inverter, 7 ... Current sensor, 8 ... Three-phase current detection circuit, 9 ... Trapezoidal wave drive synchronous AC servo motor, 10 ... Arithmetic circuit, 11 ... Absolute value circuit, 12 ... Open phase signal output circuit,
100 ... Open phase detection signal generation circuit.

Claims (1)

[Claims] 1. A three-phase current detection circuit for detecting a current of each phase (u phase, v phase, w phase) of a trapezoidal wave drive synchronous AC servomotor and outputting a three-phase current detection signal, and the three-phase current detection circuit. An arithmetic circuit for inputting a current detection signal and adding the respective signals to output an added value of currents for three phases, and an input value for the added value of currents for the three phases, and a phase loss based on the added value A phase loss detection circuit for an AC servo device, comprising: a phase loss detection signal generation circuit that outputs a detection signal.