JP2628899B2 - Inverter commutation failure detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a commutation failure detection device for an inverter which is suitable when an armature coil or the like such as a linear motor that generates an electromotive force during rotation is used as a load. It is.

B. SUMMARY OF THE INVENTION In the present invention, in a commutation failure detection circuit for an inverter, the rectified voltage across the commutation capacitor of the inverter keeps zero potential without being affected by the electromotive force of the load when the commutation of the inverter fails. By paying attention to this fact, by detecting the continuation of the zero potential and detecting the commutation failure, the commutation failure can be reliably detected even when the inverter load has an electromotive force.

C. Prior Art Conventionally, there has been an inverter as a device that connects a thyristor in a bridge form, converts an output power of a DC power supply into an AC power, and supplies the AC power to a load such as an armature coil.

FIG. 3 is a configuration diagram of a conventional current source inverter which is one of the linear motor drive circuits. This conventional example is a current type inverter operated by a DC constant current power supply 2 by connecting a plurality of bridge type inverters 1-1, 1-2, 1-3,... is there. Each inverter 1 3 the thyristors between the DC supply side P-N is _{U, 3 V, 3 X,} 3 Y and its four series of each cutting diodes _{U, 4 V, 4 X,} 4 Y set to the bridge-shaped The armature coils 5a and 5b of the linear motor are connected to the AC output sides U and V, respectively. The inverter 1 is controlled by thyristors 3 _U and 3 _Y by a control circuit (not shown).
And the set of thyristors 3 _V and 3 _X are alternately turned on, and commutation is performed by turning off the set of thyristors that are not turned on by the commutation capacitors C ₁ and C ₂ . When commutation failure occurs in one of such inverters, if the commutation is detected and the inverter is short-circuited, the linear motor can be continuously operated by another healthy inverter.

FIG. 4 is a connection diagram of a conventional commutation failure detection device.
The conventional commutation failure detection device 6 is connected between the DC supply side PN of the inverter 1 and monitors the inverter DC voltage, and detects that it becomes zero potential continuation due to commutation failure. Commutation failure was detected by

D. Problems to be Solved by the Invention However, in the commutation failure detection device in the above-described conventional technology, when the target is an inverter to which an electromotive load such as an armature coil of a linear motor is connected, There was a problem that failure could not be detected.

FIGS. 5A and 5B are waveform diagrams showing the operation of the conventional commutation failure detection device. (A) shows the operation when the load of the inverter to be detected is a load that is not an armature coil or the like (that is, a load with no electromotive force) or a bridge type inverter that does not have a cutting diode, and (b) shows the operation. The operation when the load of the inverter has an electromotive force like an armature coil of a linear motor is shown. (A)
In the case of (1), the PN voltage becomes zero. Therefore, it is possible to detect a commutation failure by detecting, for example, that the rectified waveform has a continuation state of zero potential. However, as in the inverter 1 of the linear motor drive circuit shown in FIG. 3, that is, when the load of the inverter has an electromotive force during rotation as in the armature coils 5a and 5b, even if a commutation failure occurs, the electromotive force does not occur. Since the PN voltage does not become zero due to the electric power, FIG.
As shown in (1), no commutation failure can be detected from the rectified waveform. That is, when the commutation failure occurs in the inverter 1 shown in FIG. 3, all the thyristors 3 _U , 3 _V , 3 _X , and 3 _Y are turned on, and the point U is increased by the electromotive force of the armature coils 5 a and 5 b. If the V point has a negative polarity, the cut diodes 4 _V and 4 _X conduct, and if the U point and the V point have opposite polarities, the cut diodes 4 _U and 4 _Y conduct and rectify, This is because a negative voltage is applied between PN.

Further, since the inverter shown in FIG. 3 is a current type inverter, even if a commutation failure occurs, the DC current does not increase, and it is difficult to detect the commutation failure by other means.

The present invention has been made in order to solve the above problems, and can reliably detect commutation failure of an inverter even when the load of the inverter has an electromotive force such as an armature coil of a linear motor. An object of the present invention is to provide a commutation failure detection device.

E. Means for Solving the Problems The configuration of the commutation failure detection device of the present invention for achieving the above-mentioned object comprises a commutation capacitor connected between bridge-type commutation elements constituting an inverter. A rectifier circuit for rectifying a voltage, and a zero-potential detection circuit that detects the continuation of the zero potential of the rectified voltage and outputs a detection of commutation failure.

F. Action The present invention focuses on the fact that the rectified voltage at both ends of the commutation capacitor constituting the inverter, when commutation of the inverter fails, continues at zero potential without being affected by the electromotive force of the load, By detecting the continuation of the zero potential, the commutation failure is easily and reliably detected even when the load of the inverter has an electromotive force.

G. Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing the configuration and connection of a commutation failure detection device according to an embodiment of the present invention. In this embodiment, the inverter 1 has the same configuration as the inverter 1 of the conventional example shown in FIG. 3, and the same components are denoted by the same reference numerals and description thereof will be omitted. Reference numeral 7 denotes a commutation failure detection device according to the present embodiment, which is configured as follows. A rectifier circuit 71 is connected to one of the commutation capacitors (for example, C ₁ ) of the inverter 1 using the input side as an input terminal for detecting commutation failure, and the rectified output side is connected via a current limiting circuit 72 such as a resistor. Photo coupler
73 are connected to the input side (light-emitting side). The photocoupler 73 is an element for insulation, and its output side (light receiving side) is insulated from the input side to transmit a signal. 74 is a photocoupler 73
This amplifier circuit is connected to the output side of the amplifier and performs amplification and waveform shaping of the transmitted signal to detect zero potential.It is equipped with a time lag circuit, and inverts the output at pulsed zero potential during commutation. Instead, the output is inverted at the zero potential that continues when commutation fails. The inversion of this output is used as a commutation failure detection output. The time lag circuit can be configured by an integrating circuit, a time constant circuit of a resistor-capacitor, or the like.

The operation of the embodiment configured as described above will be described. FIG. 2 is a waveform chart showing the operation of the present embodiment. As described with reference to FIG. 5 (b), the PN voltage on the DC supply side of the inverter 1 having the armature coils 5a and 5b of the linear motor as a load can be changed even if a commutation failure occurs. , 5b does not become zero potential but a negative voltage is applied. On the other hand, the voltage across the commutation capacitor C ₁ (or C ₂ ) reverses its polarity while being charged with a constant current during normal commutation. Since the potentials at both ends are equal, the potential always becomes zero regardless of the load of the inverter. Therefore, the rectified waveform by the rectifier circuit 71 continues to have zero potential (part A) after commutation failure, and is distinguished from the pulsed zero potential (part B) generated during polarity reversal during normal commutation operation. The commutation failure is detected by detecting, that is, ignoring the part B by the time lag circuit of the amplifier circuit 74 and detecting only the part A.

In this embodiment, the case where the load of the inverter has an electromotive force has been described. However, it is apparent that the commutation failure can be similarly detected when the load of the inverter has no electromotive force.
As described above, the present invention can be variously applied according to the gist and can take various embodiments.

H. Effects of the Invention As is clear from the above description, according to the inverter commutation failure detection device of the present invention, both ends of the commutation capacitor which become zero potential without being affected by the electromotive force of the load when commutation fails. The commutation failure is detected by monitoring the potential of the inverter, so that even if the load of the inverter has an electromotive force such as an armature coil of a linear motor, the commutation failure of the inverter can be easily and reliably detected. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing the configuration and connection of one embodiment of the present invention, FIG. 2 is a waveform diagram showing the operation of the embodiment, FIG. 3 is a configuration diagram of a conventional current source inverter, and FIG. FIGS. 5 (a) and 5 (b) are connection diagrams of the conventional commutation failure detection device, and FIGS. 1. Inverter, 5a, 5b ... Armature coil (load),
7 ... commutation failure detection device, 71 ... rectifier circuit, 73 ... photocoupler, 74 ... amplifier circuit.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yukio Yanagimoto 2277-17 Ohira, Numazu City, Shizuoka Prefecture (56) References JP-A-58-86875 (JP, A) JP-A-55-29271 (JP, A) Kaisho 51-97970 (JP, A)

Claims (1)

(57) [Claims] 1. A rectifier circuit for rectifying a voltage across a commutation capacitor connected between bridge-type commutation elements constituting an inverter, and commutation by detecting continuation of zero potential of the rectified voltage. A commutation failure detection device for an inverter, comprising: a zero potential detection circuit that outputs a failure detection output.