JP2710792B2 - Digital phase shifter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a power converter, and more particularly to a digital phase shifter suitable for use in phase control of a power converter such as an AC electric vehicle. About the vessel.

[Prior Art] As a prior art related to a phase shifter used for performing phase control of a power converter, for example, a technique of generating a phase shift pulse in accordance with a control delay angle command from a microcomputer or the like is known. . Hereinafter, an example of this type of prior art will be described with reference to the drawings.

FIG. 5 is a block diagram showing an example of the configuration of a conventional phase shifter, and FIG. 6 is a waveform diagram for explaining the operation thereof.
In FIG. 5, 41 to 44 are timers.

The prior art shown in FIG. 5 uses timers 41 to 44 as phase shifters. The timers 41 to 44 operate using the AC voltage 14 as a power source shown in FIG. 6 as a timing signal with the zero-cross signal 15 as a timing signal, and the output thereof is used for controlling the corresponding one stage of the rectifying bridge.

The waveform diagram shown in FIG. 6 explains the operation of one timer, for example, the timer 41. Fifth
In FIG. 6 and FIG. 6, the control delay angle command 45 is issued as a preset value of the timer 41. This control delay angle command 45
The timer 41 is synchronized with the zero-cross signal 15 of the AC voltage 14.
And the timer 41 immediately starts subtracting the given command 45. Then, when the count value reaches “0”, the timer 41 outputs a firing signal 46 to the rectifying bridge. The firing signal 46 is continuously output by the next zero-cross signal 15 until the command 45 is taken into the timer 41. Therefore, the prior art shown in FIG.
By changing the magnitude of the control delay angle command 45 given to the motor, it is possible to adjust the pulse width of the ignition signal 46 for rectifying bridge control. Similarly, the other timers 42 to 44 output the firing signal 46 for controlling the corresponding commutation bridge in response to the control delay angle commands applied to the respective timers.

In addition, as a prior art regarding the phase shifter as described above,
For example, the techniques described in JP-A-57-168315 and JP-A-60-96194 are known.

[Problems to be Solved by the Invention] In the conventional technique, since the count value of the timer changes every moment, it is difficult to change the control delay angle command 45 at an arbitrary timing. It was almost impossible to change the control delay angle command 45 multiple times within a half cycle. For this reason, it is difficult for the above-mentioned conventional technology to perform control response at high speed. For example, when there is a disturbance such as a fluctuation of a power supply voltage, the control delay angle command is immediately changed, and the influence is affected. However, there is a problem that it is difficult to reduce the

Further, the conventional technique has a problem that when controlling a power converter having a plurality of rectifying bridges, the same number of phase shifters as the number of rectifying bridges are required.

An object of the present invention is to solve the above-described problems of the related art, to enable control delay angle commands to be changed at an arbitrary timing, to improve control responsiveness, and to improve the control responsiveness even when the number of commutation bridges is plural. An object of the present invention is to provide a digital phase shifter in which these can be controlled by one phase shifter.

Means for Solving the Problems According to the present invention, the object is to provide a power converter that obtains a direct current through a plurality of rectifier bridges connected in series from an AC power supply to generate an ignition command for the rectifier bridge. In the phaser, a means for outputting a signal corresponding to the electrical angle of the power supply voltage, a means for holding a control delay angle command, a comparing means for comparing the outputs of these means, and an output of the comparing means Distributing means for distributing to one of the rectifying bridges, and means for holding the distributed output up to the next zero-cross position of the AC voltage, and outputting the held output as a firing command for the rectifying bridge. This is achieved by:

[Operation] A value corresponding to the electrical angle of the AC voltage is given to one input of the comparator, and a control delay angle command is given to the other input. Then, these magnitude relationships are compared by a comparator, and the comparison result is output as a firing command. According to such a configuration, it is not necessary to change the control delay angle command according to the AC electrical angle. (In the prior art, when the control command is desired to be changed at a point other than the zero cross point of the AC voltage, It is necessary to change the command value according to the electrical angle.), And it is possible to change the control delay angle command at an arbitrary timing.

Further, the output of the comparator, that is, the firing command is given as a firing command to a certain rectifying bridge by a selection circuit such as a demultiplexer, and an ON or OFF command is given to other rectifying bridges. ,
A single phase shifter can control a plurality of rectifying bridges.

Hereinafter, an embodiment of a digital phase shifter according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a waveform chart for explaining the operation. In FIG. 1, 1 is a counter, 2, 5, 7 are flip-flops, 3 is a comparator, 4 is a demultiplexer, 6 is a logic circuit,
8 is a gate pulse generator, 9 is a pantograph, 10 is a transformer, 11 is a rectifier, 12 is a load, and 14 is an overhead wire.

An embodiment of the digital phase shifter according to the present invention shown in FIG. 1 counts the clock signal 27 and outputs the AC voltage shown in FIG.
The counter 1 outputs data corresponding to the electrical angle of the AC voltage 14 by being reset by the zero cross signal 15, the flip-flop 2 for latching the control delay angle command 28, and the output of the counter 1 is compared with the output of the flip-flop 2. A comparator 3, a demultiplexer 4 for switching the output destination of the comparator 3, a flip-flop 5 for latching the ignition command 29, a logic circuit 6 for performing a logical operation on the outputs of the demultiplexer 4 and the flip-flop 5, and a logic circuit 6
Is held until the zero-cross signal 15 is supplied.

The power converter to be controlled by the digital phase shifter according to one embodiment of the present invention configured as described above is, for example, a main circuit in an AC electric vehicle, and includes a gate pulse generator, a rectifier 11, and a transformer. And 10. The main circuit is an overhead line obtained through the pantograph 9
The AC power from 14 is received by the transformer 10, and the load 12 such as a vehicle drive motor is driven via the rectifier 11. Rectifier 11
A plurality of rectifying bridges are connected in series,
One rectifier bridge is controlled by a gate control signal provided from the gate pulse generator 8, and the other rectifier bridge is controlled to be turned on or off to control its output voltage.

In the waveform diagram shown in FIG. 2, the triangular wave 16 is a clock.
The output of the counter 1 that counts 27 is represented by an analog signal, and corresponds to the electrical angle of the AC voltage 14. The step-like waveform 17 is a control delay angle command output after being temporarily latched by the flip-flop 2 receiving the control delay angle command 28. The comparator 3 compares the output of the counter 1 with the output of the flip-flop 2,
Output of flip-flop 2, ie, control delay angle command
Generates an output when 17 becomes large. This output is a phase shift signal whose pulse width is widened when the control delay angle command 17 becomes large, and becomes an ignition signal for the rectifying bridge, as shown in a waveform 18. This signal is input to the demultiplexer 4.

Attention is now directed to the two outputs 20, 21 of the demultiplexer 4. The demultiplexer 4 outputs the control signal
When the signal 19 is "0", the input signal 18 is transmitted to the output 20, and when the control signal 19 is "1", the phase shift signal 18 is transmitted to the output 21. Control signal 19 is “0”,
It is assumed that the outputs 22, 23 of the flip-flop 5 are "0".
The flip-flop 5 receives the firing command 29 and latches information indicating which rectifying bridge in the rectifier 11 is to be turned on.

Since the control signal 19 is "0" before the time t1, the phase shift signal 18 is transmitted to the output 20 of the demultiplexer 4 and applied to the logic circuit 6. Since the output 22 of the flip-flop 6 applied to the logic circuit 6 is "0", the phase-shifted signal 18 from the output 20 latches the phase-shifted signal 18 as it is until the next zero-cross signal. The signal is supplied to the gate pulse generator 8 via the flip-flop 7 as a firing command signal 24. Gate pulse generation circuit 8
Thus, the rectifier bridge is controlled by applying a gate control signal based on the phase shift signal 18 to the first rectifier bridge at the lowermost stage of the rectifier 11. At this time, the other rectifying bridges are in the off state, and the output voltage of the rectifier 11 has a waveform as shown in a portion of the waveform 26 before the time t1.

At time t1, the control signal 19 of the demultiplexer 4 becomes "1", and the output 22 of the flip-flop 5 becomes "1". As a result, the phase shift signal 18 is output from the demultiplexer.
21, a logic circuit 6 and a flip-flop 7 are supplied to the gate pulse generator 8 as a firing command signal 25. When the output 22 of the flip-flop 5, that is, the firing command for the first rectifying bridge becomes "1", the firing command signal 24 which is the output of the flip-flop 7 is output.
Is a signal of the control delay angle “0”. The gate pulse generator 8 thereby controls the first rectification bridge at the lowermost stage to be in an ON state, and supplies a gate control signal based on the phase shift signal 18 to the next second rectification bridge to rectify the same. Control the bridge. At this time, the other rectifier bridges in the upper stage are in the off state, so that the output voltage of the rectifier 11 is changed to the uncontrolled output voltage of the first rectifier bridge and the controlled second rectifier bridge. Are added to form a waveform 26 after time t1. By continuing such control, the output voltage of the rectifier 11 becomes
It is controlled to gradually rise. Similarly, a rectifier
It is also possible to perform control for lowering the output voltage of 11.

In the above-described embodiment of the present invention, as described above, the gate control is performed on one of the rectifying bridges in the rectifier 11 by the control delay angle command 28 and the firing command 29, and the other rectifying bridge is turned on or off. Can be controlled off,
A rectifier composed of a plurality of rectifier bridges connected in series can be controlled by one phase shifter, and the control delay command can be changed at any time without being restricted by the electrical angle of the AC voltage. And control with high responsiveness can be performed.

FIG. 3 is a block diagram showing the configuration of another embodiment of the present invention, and FIG. 4 is a waveform diagram for explaining the operation. In FIG. 3, reference numeral 13 denotes a ROM, and other symbols are the same as those in FIG.

Another embodiment of the present invention shown in FIG. 3 is that the output of the counter 1 is given as an address signal of the ROM 13 and the output 27 of the ROM 13 is given to the comparator 3 as a signal corresponding to the electrical angle of the AC voltage 14. 1 is different from the embodiment shown in FIG.
It is configured similarly.

Generally, in the phase control of the AC voltage, the ratio of the DC output voltage of the rectifier to the AC voltage is (1 + cos α) / 2, where α is the control delay angle. Therefore, in the embodiment of the present invention shown in FIG. 3, the data in the ROM 13 is stored in the waveform 27 shown in FIG.
As shown in (1), it is set so that a waveform of (1 + cosα) / 2 is output. In the embodiment shown in FIG. 3, the control delay angle command 28 and the output voltage of the rectifier 11 can thereby be in a proportional relationship, and the nonlinearity can be canceled out, thereby improving the control performance. be able to.

Although the above-described embodiment of the present invention has been described as being used for controlling a rectifier in a main circuit of an electric vehicle, the present invention can be used in other technical fields such as changing a DC voltage applied to a load. .

[Effects of the Invention] As described above, according to the present invention, since the control delay angle command can be changed at an arbitrary timing, for example, control can be performed at high speed even with disturbances such as power supply voltage fluctuations. The delay angle command can be adjusted, the control performance can be improved such as the effect of disturbance can be reduced, and even when a plurality of rectifying bridges are provided,
Can be handled by one phase shifter according to the present invention,
In particular, it is possible to reduce the size of the control device for controlling the multi-stage rectifier.

Further, according to the present invention, by using the ROM, it is possible to generate a signal such that the control delay angle command and the rectifier output voltage are in a proportional relationship, so that the nonlinearity between the command and the output voltage can be canceled. This makes it possible to further improve control performance.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention, FIG. 2 is a waveform diagram illustrating the operation thereof, FIG. 3 is a block diagram showing the configuration of another embodiment of the present invention, and FIG. FIG. 5 is a waveform diagram for explaining the operation, FIG. 5 is a block diagram showing an example of the configuration of the prior art, and FIG. 6 is a waveform diagram for explaining the operation. 1 ... Counter, 2,5,7 ... Flip-flop, 3 ...
Comparator, 4 Demultiplexer, 6 Logic circuit, 8 Gate pulse generator, 9 Pantograph,
10 …… Transformer, 11 …… Rectifier, 12 …… Load, 13 …… RO
M, 14 ... overhead wire.

Claims (2)

(57) [Claims] 1. A phase shifter for generating an ignition command for said rectifier bridge in a power converter for obtaining a direct current through a plurality of rectifier bridges connected in series from an AC power supply,
Means for outputting a signal corresponding to the electrical angle of the power supply voltage, means for holding a control delay angle command, comparing means for comparing the outputs of these means, and the output of the comparing means to one of the plurality of rectifying bridges. And distributing means for distributing the rectifier bridge, and means for retaining the distributed output to the next zero-cross position of the AC voltage, and outputting the retained output as a firing command for the rectifying bridge. Digital phase shifter. 2. The apparatus according to claim 1, further comprising means for performing a logical operation on an output of said distribution means and a firing command for another rectifier bridge not controlled by the output of said distribution means. Digital phase shifter.