JP4910569B2 - Output phase loss detection circuit of power conversion controller - Google Patents

Description

The present invention, the three-phase AC motor for the output phase failure detection Demawa path of the power converter control apparatus for a variable speed drive with vector control.

  FIG. 3 is a circuit configuration diagram showing a conventional example of an output phase loss detection circuit in this type of power conversion control device, where 1 is an induction motor as an AC motor, 2 is connected to the output shaft of the induction motor 1, and the motor Reference numerals 3 and 4 denote current detectors (CT) for detecting a current flowing from the power conversion control device 10 to be described later to the induction motor 1.

The power conversion control device 10 is instructed by a three-phase power converter 11 formed by a DC power source such as a rectifying power source, a reverse conversion circuit formed by connecting a reverse-parallel circuit of a transistor and a diode in a three-phase bridge, and the like. A deviation calculator 12 for obtaining a deviation between the speed command value to be obtained and the rotational speed of the induction motor 1 obtained based on the incremental signal from the position detector 2, and an adjustment calculation so that the deviation becomes zero. Is output as a torque current command value of the induction motor 1, and a voltage control of the induction motor 1 is performed by performing a vector control calculation based on the torque current command value, the electric constant of the induction motor 1, an excitation current command value, and the like. A vector controller 14 for deriving a value, and a PWM pulse for generating a drive pulse to the three-phase power converter 11 by controlling the voltage command value by pulse width modulation (PWM). As the output phase loss detection circuit in the power conversion control device 10, the calculator 15, the subtraction calculator 21 that generates the V-phase detection current from the detection currents from the CTs 3 and 4, and the detection currents of these three phases, respectively. Current comparators 22 to 24 that output a logic H level when the absolute value of the current becomes equal to or less than a predetermined threshold value, an OR circuit 25 that receives the output values of the current comparators 22 to 24, and OR An AND circuit 26 that receives an output value of the circuit 25 and a logic level value based on the speed command value, a pulse width measuring circuit 27 that measures a period during which the output value of the AND circuit 26 is at a logic H level, and this measurement. A comparison circuit 28 that determines that at least one of the phase outputs of the power conversion control device 10 has lost phase and outputs an open phase signal when the period exceeds a predetermined comparison set value. It is equipped with a.
JP 2001-251866 A

  In the output phase loss detection circuit in the power conversion control device 10 shown in FIG. 3, the logic level value based on the speed command value as one input value of the AND circuit 26 is a logic H level in the variable speed range of the induction motor 1. However, there are cases where it is difficult to achieve the logic H level particularly when the induction motor 1 is driven at a variable speed near zero speed.

  Further, in order to cope with the fact that the period of the logic H level in the output value of the AND circuit 26 varies depending on the rotation speed of the induction motor 1, that is, the drive frequency and the current value flowing from the power conversion control device 10 to the induction motor 1, The comparison set value in the comparison circuit 28 with respect to the value measured by the measurement circuit 27 is a large value, that is, a long-time value, and particularly when the induction motor 1 is rotating at a high speed, the generation of the phase loss signal is delayed. There were difficulties.

The purpose of the invention is to provide an output phase detection Demawa path of the power converter control apparatus to solve the above problems.

The inventions of this, in the power conversion control apparatus for variable speed drive with vector control of three-phase AC motor,
Three sets of current comparators that output a logic H level when the absolute value of each phase output current of the power conversion control device falls below a predetermined threshold value, and the output values of the current comparators An OR circuit as an input, an AND circuit that receives a logical level value based on an output value of the OR circuit and a voltage command value for vector control of the AC motor, and an output value of the AND circuit is a logic H level A rotation angle measuring device for measuring the rotation angle of the AC motor in the period of at least one of the phase outputs of the power conversion control device when the measured rotation angle exceeds a predetermined angle setting value An output phase loss detection circuit of a power conversion control device is provided, which includes a comparison operation unit that determines that one phase has been lost and outputs a phase loss signal .

  According to the present invention, when the AC motor, in particular, the induction motor is vector-controlled, the voltage command value corresponding to the excitation current is generated even when the induction motor is in the vicinity of zero speed. It is easy to generate a logic H level based on this, and each excitation current is included in each phase output current of the power conversion control device, and the absolute value of each phase output current is calculated as described above. By measuring the rotation angle of the AC motor below the threshold value, the phase loss signal can be more reliably generated, and the detection delay when the phase loss signal is generated can be minimized.

  FIG. 1 is a circuit configuration diagram showing an embodiment of an output phase loss detection circuit in the power conversion control device of the present invention. In this figure, the circuit configuration having the same function as the circuit configuration of the conventional example shown in FIG. The same reference numerals are given and the description thereof is omitted here.

  That is, the output phase loss detection circuit in the power conversion control device 30 includes the subtraction calculator 21, the current comparators 22 to 24, the OR circuit 25, the logic level value based on the output value of the OR circuit 25 and the voltage command value. , An input circuit 31 that is closed when the output value of the AND circuit 31 is at a logic H level, and a position detector via the switch 32 when the output value of the AND circuit 31 is at a logic H level. A rotation angle measuring unit 33 that measures the number of incremental signals from 2 and outputs the measured value as the rotation angle of the induction motor 1, and a power conversion control device when the rotation angle exceeds a predetermined angle set value. A comparison operation unit 34 is provided that determines that at least one of the 30 phase outputs is out of phase and outputs an out-of-phase signal.

  The operation of the output phase loss detection circuit in the power conversion control device 30 shown in FIG. 1 will be described below with reference to the waveform diagram shown in FIG.

  First, the current flowing from the power conversion control device 30 to the induction motor 1 changes as shown in FIG. 2 (a), the solid line indicates the waveform when the induction motor 1 is in a normal driving state, and the broken line indicates that the motor is unloaded. The waveform is shown when rotating in a state, that is, when the excitation current is substantially only.

  Therefore, when the absolute value of each of the three-phase detection currents in the broken line state is equal to or lower than a predetermined threshold value, the threshold values in the current comparators 22 to 24 that output a logic H level are: As shown in FIGS. 2 (b) to 2 (d), the values at which the logic H level period is less than 60 ° in terms of the electrical angle based on the drive frequency of the induction motor 1, for example, the electricity based on the drive frequency of the induction motor 1. The angle is set to a value of about 50 °.

  Therefore, the logical value of the output of the AND circuit 31 changes as shown by the solid line in FIG. 2 (e) when the solid line state of FIG. It changes like the broken line 2 (e).

  As a result, the rotation angle measurement value of the induction motor 1 in the rotation angle measuring instrument 33 is a state in which the output of the AND circuit 31 increases from 0 to a sawtooth waveform during the logic H level as shown in FIG. repeat. At this time, the value corresponding to the number of incremental signals from the position detector 2 via the switch 32 corresponding to, for example, one rotation of the induction motor 1, that is, about 360 ° is set as the angle setting value in the comparison calculator 34. Thus, in the comparison calculator 34, when the rotation angle measurement value of the induction motor 1 in the rotation angle measuring device 33 exceeds the angle setting value, at least one of the respective phase outputs of the power conversion control device 30. It is determined that the phase has been lost, and an open phase signal is output.

  That is, according to the output phase loss detection circuit in the power conversion control device 30, the rotation angle of the induction motor 1 when the absolute value of each phase output current of the power conversion control device is equal to or less than the threshold value is measured. Thus, the phase loss signal can be more reliably generated, and the detection delay when the phase loss signal is generated can be minimized.

  In addition, the power conversion control device 30 displays and reports to the outside that the phase loss signal has been generated, and also shuts off the base for each of the transistors forming the three-phase power converter 11 by the phase loss signal. Like to do.

Configuration diagram of output phase loss detection circuit of power conversion control device showing an embodiment of the present invention Waveform diagram explaining the operation of FIG. Configuration diagram of output phase loss detection circuit of power conversion control device showing a conventional example

DESCRIPTION OF SYMBOLS 1 ... Induction motor, 2 ... Position detector, 3, 4 ... CT, 10 ... Power conversion control apparatus, 11 ... Three-phase power converter, 12 ... Deviation calculator, 13 ... Speed regulator, 14 ... Vector controller, DESCRIPTION OF SYMBOLS 15 ... PWM pulse calculator, 21 ... Subtraction calculator, 22-24 ... Current comparator, 25 ... OR circuit, 26 ... AND circuit, 27 ... Pulse width measuring circuit, 28 ... Comparison circuit, 30 ... Power conversion control apparatus, 31 ... AND circuit, 32 ... switch, 33 ... rotation angle measuring device, 34 ... comparison arithmetic unit.

Claims (1)

In a power conversion control device that drives a variable speed while performing vector control of a three-phase AC motor,
Three sets of current comparators that output a logic H level when the absolute value of each phase output current of the power conversion control device falls below a predetermined threshold;
An OR (logical sum) circuit that receives the output value of each of the current comparators;
An AND (logical product) circuit that receives a logical level value based on an output value of the OR circuit and a voltage command value when the AC motor is vector-controlled;
A rotation angle measuring device for measuring the rotation angle of the AC motor during a period when the output value of the AND circuit is at a logic H level;
A comparison operation for determining that at least one of the phase outputs of the power conversion control device has lost phase and outputting an open phase signal when the measured rotation angle exceeds a predetermined angle setting value. And an output phase loss detection circuit for a power conversion control device.

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