JPS5855755B2 - How to control cycloconverter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power conversion device configured by connecting at least two unit self-excited syrisk converters in antiparallel to each other, or a self-excited syrisk converter and a separately excited syrisk converter as a unit. The present invention relates to a method of controlling a cycloconverter configured by combining a plurality of converters.

Figure 1 is a configuration diagram showing an example of a cycloconverter constructed by combining unit converters, and Figures 2a and b are detailed diagrams showing the specific configuration of each converter in Figure 1. be.

In FIG. 1A, A1 and A2 are separately excited Sirisk converters, respectively, and as shown in FIG. 2A, three
Phase alternating current power supply vR2 vs, vT (consisting of six cyrisks U1 to z1 connected in a three-phase bridge, and B
1. B2 is a self-excited Sirisk converter, respectively, and B2 is a 3-phase bridge connected 6, as shown in FIG.
thyristors U2 to z2 and a forced commutation circuit.

The forced commutation circuit includes upper thyristors U2 to W2 (common capacitor cU, commutating reactor LU, auxiliary charging thyristor UQ, and reverse arc-extinguishing thyristor UP, and a commutating capacitor common to lower thyristors X2 to Z2). cD, a commutating reactor LD, a replenishing heavy-duty thyristor LQ, an inverted arc-extinguishing thyristor LP, and a commutating capacitor charging diode bridge DU-DZ.

Note that R1 and R2 are resistors.

As is well known, when these unit converters are connected as shown in FIG.
2, while self-excited converter B1. By performing advanced phase control on B2, it is possible to provide a so-called reactive power compensation type power converter in which the reactive power that the power converter takes in from the power supply system can be substantially reduced to zero.

Each unit converter constituting such a power converter has an A1. B,
and A2. operating on each negative half-wave. For example, if the polarity of the output current target value is determined, the current switching command circuit Pl will change the converter to which one belongs. This is done by selecting a group.

On the other hand, the output voltage or output current of a power converter can be controlled by how the firing phase or gate pulse is applied to the power supply voltage of each sirisk, but in order to obtain a good sine wave output current (this is , it is necessary for the converter to output a full output voltage at the switching point or the polarity change point of the output current in each cycle.

In other words, if the output voltage phase of the self-excited converter becomes negative polarity when the polarity of the output current changes, the converter will not operate even if the gate pulse is applied until this becomes a positive voltage phase. No output voltage can be generated, and therefore the time during this period is wasted.

Therefore, this invention was made in view of the above,
It is an object of the present invention to promptly obtain the maximum output voltage that the converter can output at that time immediately after changing the polarity of the output current in a power converter.

The above object is achieved by the present invention (according to which at least two self-excited thyristor converters each including a plurality of thyristors and a forced commutation circuit are connected in antiparallel to each other to supply a load current of variable polarity to a load). A cycloconverter comprising: a current switching command circuit that selectively operates one of the converters in accordance with a desired polarity of the load current; and a switching command I from the current switching command circuit. a gate pulse supply circuit that supplies gate pulses of a certain time width to the gates of each cyrisk constituting one of the selected converters at a predetermined timing, and an additional pulse of a predetermined time width in response to the switching command. This is achieved by providing a pulse generation circuit that generates a pulse, and when the switching command is generated, superimposing the additional pulse on the gate pulse output of the gate pulse supply circuit and supplying the gate pulse to the entire signal risk.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic configuration diagram showing an embodiment of the present invention.

In the same figure, the gate pulse is determined by comparing the phase control signal SP created by comparing the current value of the output current with the target value and the synchronization signal 5Y (u=z) created from the power supply voltage. A comparator 1 that determines the generation timing, a flip-flop 2 that operates for a time corresponding to 120 degrees (electrical angle) in response to the output of the comparator 1 and outputs a pulse signal, and a flip-flop 2 that receives the switching signal SS and outputs a pulse signal. For example, a gate pulse generation circuit is shown that includes a monostable multi 4 and an OR circuit 3 that performs an OR operation between the output of a flip-flop 2 and the output of the pulse generation circuit 4. There is.

Therefore, at the time when the switching signal SS is applied, it is assumed that each of the predetermined thyristors U2 to W2 and X2 to Z2, which are determined by the phase control signal SP and the synchronization signal SY, is driven once. However, in this invention, the additional pulse output from the pulse generating circuit 4 is supplied to each gate of all thyristors U2 to Z2 through the OR circuit 3, so that it is determined at the above-mentioned point in time. Not only the pair of Cyrisks but also all other Cyrisks become conductive.

Since this includes a sirisk that can output the maximum output voltage at that time, the resulting σ conversion device can output the maximum output voltage at that time.

As described above, according to the present invention, wasted time during switching operation of the converter can be eliminated with a simple circuit configuration.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an example of a cycloconverter configured by combining a self-excited converter and a separately-excited converter, and Fig. 2 shows a specific configuration of the self-excited converter and separately-excited converter. The detailed diagram, FIG. 3, is a schematic configuration diagram showing an embodiment of the present invention. Code explanation, A1. A2...Separately excited converter, B1.
B2...Self-excited converter, 1...Comparator,
2...Flip-flop, 3...OR circuit, 4...monostable multi.

Claims (1)

[Claims] 1 a plurality of Cyrisk converters, a current switching command circuit that issues a switching command to select one of the converters in response to a desired polarity of a load current supplied from the converters to a load, and a current switching command circuit that selects one of the converters; It consists of a gate pulse supply circuit that supplies a gate pulse at a predetermined timing to each of the cyrisks constituting one converter selected based on a command, and the circuit ignites each thyrisk of the converter by means of the gate pulses. In this method, a pulse generation circuit is provided which generates an additional pulse of a predetermined duration in response to the switching command and supplies it to the gates of all the cycloconverters. . A control method for a cycloverter, characterized in that the gate pulse output of the gate pulse supply circuit (the additional pulse is superimposed on the gate pulse output) to generate each gate pulse of the total cyrisk.