JPS6156697B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase-controlled thyristor rectifier for extracting a predetermined DC output from an AC power supply depending on the magnitude of an input signal.

As an example of a conventional phase-controlled thyristor rectifier, one configured to control the rotational speed of an electric motor is shown in FIG. The electric motor 1 to be controlled is
It is configured to rotate at a rotation speed corresponding to the magnitude of the inflow current supplied to the field coil 2,
The rotation speed is detected as the magnitude of the DC voltage by a tachometer generator 4 directly connected to the rotation shaft,
The output signal of this tachometer generator 4 is supplied to a regulating device 10 . This adjustment device 10 includes a rotation speed setting device 11 that generates an output signal corresponding to a desired rotation speed.
and a deviation detector 12 that detects the deviation between its output signal and the output signal of the tachometer generator 4. After being operationally amplified in the mixer 16 and mixed in the mixer 16, it is given to the ignition device 19 as a phase control signal. Note that other correction signals may be added to the mixer 16 as necessary, and the adjustment device 10 is constructed of a digital circuit using a microprocessor or the like instead of the analog circuit shown in the figure. Sometimes.

The ignition device 19 has the function of generating a ignition pulse at a phase angle corresponding to the magnitude of the phase control signal applied from the adjustment device 10, and this ignition pulse is supplied to the thyristor amplifier 20. The thyristor amplifier 20 operates to extract a DC current corresponding to the phase angle of the firing pulse from an AC power source (not shown) connected via the power transformer 5, and this DC current flows through the circuit breaker 3. It is supplied to the field coil 2 of the electric motor 1 via the electric motor 1, and the rotational speed of the electric motor 1 is controlled here.

Most of the thyristor amplifiers 20 are of the three-phase bridge type, but for the sake of simplicity, a single-phase bridge type is shown in FIG. In FIG. 2, four thyristors 22A to 22D are connected to a power transformer 5.
constitutes a bridge circuit that double-wave rectifies the AC power supplied from the AC power source through
21D, resistors 23A to 23D, surge voltage absorbing capacitors 24A to 24D, surge voltage dividing resistors 25A to 25D, and surge voltage absorbing celestors 26A to 26D. Also, on the output side of the bridge circuit, a resistor 27 and a capacitor 28 for absorbing surge voltage, and a dummy load 2 are installed.
9 is connected.

In a conventional device having such a configuration, if even one of the elements is damaged, the electric motor 1 must be stopped until the failure is repaired. In order to prevent such a stoppage, it is necessary to duplicate the device, but although it is relatively easy to duplicate the adjustment device 10, it is difficult to duplicate the thyristor amplifier 20. If a failure occurs in this part, the electric motor 1 must be stopped.

This invention was made to eliminate the drawbacks of the conventional ones as described above.In addition to the first thyristor amplifier, a second thyristor amplifier for backup is provided, and if the first thyristor amplifier fails. To provide a phase-controlled thyristor rectifier which can switch to a second thyristor amplifier to continue operation of a load without giving a shock to the load when the load occurs.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, a motor 1, a field coil 2,
The structure and operation of the circuit breaker 3, tachometer generator 4, power transformer 5, ignition device 19, and thyristor amplifier 20 are the same as shown in FIG. 1, so the same parts are designated with the same reference numerals. , a detailed explanation thereof will be omitted.

In the device of FIG. 3, the first thyristor amplifier 2
0, a second thyristor amplifier 30 is provided for backup. This second thyristor amplifier 30 has the same configuration as the first thyristor amplifier 20, and extracts a DC current corresponding to the phase angle of the ignition pulse given from the ignition device 31, and outputs a direct current corresponding to the phase angle of the ignition pulse given from the ignition device 31. It has the function of supplying the magnetic field to the field coil 2.

When the first thyristor amplifier 20 is operating normally, the circuit breaker 3 is closed and the circuit breaker 6 is open. In such a state, in order to obtain bumpless operation that does not generate a shock even when the circuit breaker 3 opens and the circuit breaker 6 closes, it is necessary to It is necessary that the output of the thyristor amplifier 30 always follows. One of the features of this invention is that the second thyristor amplifier 20
Instead of following the thyristor amplifier 30, each AC input terminal of the thyristor amplifiers 20 and 30 is supplied with the same voltage by the power transformer 5 (for example, from two secondary coils provided in the power transformer 5). By providing a backup system that precisely follows the phase of the ignition pulse (applying the same voltage to both thyristor amplifiers 20 and 30), the second thyristor amplifier 30
The DC output of the first thyristor amplifier 20 is made to follow the DC output of the first thyristor amplifier 20. If we track the DC output as a reference, if we detect the DC output with a minute current, the load impedance will become infinite (when the circuit breaker 6 is open), the thyristor amplifier 3
The DC output at 0 becomes larger than the actual voltage, and if the circuit breaker 3 is opened and the circuit breaker 6 is closed while following this voltage, this difference in DC output will occur as a shock.

In order to make the DC output of the second thyristor amplifier 30 follow the DC output of the first thyristor amplifier 20 based on the phase of the firing pulse as described above, in the apparatus shown in FIG. A difference detection device 32 is provided. This device 32 compares the phase of the ignition pulse supplied to the thyristor amplifier 20 with the phase of the ignition pulse supplied to the thyristor amplifier 30, and if the former is ahead, this phase difference is determined. If the former is delayed, a negative output proportional to this phase difference is generated, and if both are in phase, the output is zero. I do.
The output of this ignition phase angle difference detection device 32 is directed to an ignition pulse phase difference indicator 37.

On the other hand, a manual setting device 34 is provided for setting the phase of the ignition pulse generated by the ignition device 31. Therefore, when the setting value of this manual setting device 34 is manually changed, the phase of the ignition pulse that the ignition device 31 supplies to the second thyristor amplifier 30 changes, and as a result, the phase of the ignition pulse that the ignition device 31 supplies to the second thyristor amplifier 30 changes. DC output changes. At the same time, ignition device 3
The change in the phase of the ignition pulse generated by ignition device 19 changes the phase difference between the phase of the ignition pulse generated by ignition device 19, and therefore the indicator 37 indicates this phase difference. Change the value. By adjusting the manual setter 34 so that the indicated value of the indicator 37 becomes zero, the phase difference between the firing pulses supplied to the first and second thyristor amplifiers 20 and 30 can be determined. This means that the difference in DC output between the two can be reduced to zero,
Even if the circuit breakers 3 and 6 are opened or closed in this state, no shock is given to the electric motor 1, which is the load.

Further, FIG. 4 shows a firing pulse supplied to the second thyristor amplifier 30 with respect to a firing pulse supplied to the first thyristor amplifier 20 using the output of the firing phase angle difference detection device 32. This shows a case in which the phase of is automatically tracked. That is, in FIG. 4, the output of the firing phase angle difference detection device 32 is converted into a pulse signal by the PFM servo amplifier 33, and then a contact is sent to the motor 35 for automatically changing the setting value of the manual setting device 34. 36. As a result, the setting value of the manual setting device 34 is automatically changed so that the output of the ignition phase angle difference detection device 32 is always zero, and The DC output of the second thyristor amplifier 30 follows.

Of course, if the thyristor amplifiers 20 and 30 are configured as three-phase bridges, the firing pulse phases of the same arms of the same phase are compared. If the firing pulse phase is accurately followed as described above, even if the main control system fails at any point, the circuit breaker 3 will immediately open and the circuit breaker 6 will close (at this time, the contact 36 will not open). The operation of the electric motor 1 can be continued simply by switching to . In this case, the rotation speed of the electric motor 1 is adjusted by manually adjusting the manual setting device 34.

In addition, after the failure of the main control system is repaired, 2
The output level of the firing phase angle difference detection device 32 corresponding to the phase difference between the firing pulses supplied to the two thyristor amplifiers 20 and 30 is read by the indicator 37,
Rotation speed setting device 11 so that the indicated value becomes zero
After adjusting, the circuit breakers 3 and 6 and the contacts 36 are switched. As a result, operation by the main control system is resumed.

FIG. 5 shows an example of a specific circuit configuration of the ignition phase angle difference detection device 32. In FIG. 4, the input to transformer 40 is the same light current supply voltage as that applied to thyristor amplifiers 20,30. Of course, the power supply voltage of the phase corresponding to the phase in which the firing pulse of the thyristor amplifier 20 is detected is introduced, and the 0° (point where the voltage changes from negative to positive) of the phase is detected. Also, the ignition pulse transformer 41
and 42 are each provided with a tertiary winding, and the pulses appearing in the tertiary windings are compared in phase with each other. Reference numerals 44 to 46 are silicon diodes, 47 to 49 are resistors, zener diodes 50 to 52 are used to remove harmful overvoltage to the next stage circuit, and capacitor 5 is used to remove harmful overvoltage.
3 to 55 are inserted to absorb surge voltage.

First, when the input becomes positive, 2 of the transformer 40
The input of the NAND gate 56 connected to the next winding becomes "H", its output becomes "L", and the direct connection R-S
A flip-flop (hereinafter referred to as "FF1") 61 is set, and its output becomes "H". Next, when a pulse appears at the input of the transformer 41, the input of the NAND gate 57 becomes "H", so the output of the NAND gate 58 becomes "H", and this output is directly connected to the R
-S flip-flop (hereinafter referred to as "FF2") 62. Also, when a pulse appears at the input of the transformer 42, the input of the NAND gate 59 becomes "H".
At this time, the output of the NAND gate 60 becomes "H", and this output is input to the direct-coupled R-S flip-flop (hereinafter referred to as "FF3") 63. In addition to the output of the NAND gate 58, the input of FF262 includes FF16.
1, the outputs of FF362 and reset signal generator 73 are given, and the input of FF363 is supplied with FF16.
1, the outputs of FF 262 and reset signal generator 73 are given. This reset signal generator 7
No. 3 generates an "L" level reset pulse at fixed time intervals (for example, every 0.1 to 0.2 seconds).

As shown on the left side of Figure 6, after the input voltage becomes positive, if a pulse appears on the input and in this order, at the time the pulse first appears on the input, FF161 is in the set state and FF363 is in the reset state. Therefore, all inputs of FF262 become "H", and this FF262 is set and its output becomes "L". The output of this "L" is
Since it is added as a lock signal to the input of FF363, even if a pulse appears at the input next time, FF3
63 is never set and its output remains at "H". When the output of FF262 becomes "L", the output of NAND gate 66 becomes "H"
Then, the output of the NAND gate 67 becomes "L", and the mercury contact relay 81 operates. At the same time, the pulse generation circuit 74 generates an "L" pulse, and upon receiving this "L" pulse, an R-S flip-flop (hereinafter referred to as
FF4'')64 is set and its output becomes ``H''. Note that the FF 464 is reset when a pulse appears at the input and when a reset pulse is applied from the reset pulse generator 73. Then, while the output of the FF464 is "H", the NAND gate 70 is opened, and a signal obtained by dividing a pulse with an accurate frequency (for example, 1.5 MHz) generated by the crystal oscillator 76 by the binary counter 77 is sent to the NAND gate 70.
and is applied to one input of the NAND gate 72. Next, when a pulse appears on the input,
Since FF464 is reset and its output becomes "L", the output of NAND gate 70 remains "H".

On the other hand, as shown on the right side of Figure 6, if the input pulse appears more than the input pulse,
FF363 is set before FF262, and its output locks FF262 in the reset state. The "L" output of FF363 is sent to the mercury contact relay 82 via NAND gates 68 and 69.
At the same time, the pulsing circuit 75 generates a pulse, thereby setting the R-S flip-flop (hereinafter referred to as "FF5") 65. FF5
65 is set, its output becomes "H", and this "H" output opens the NAND gate 71, and the constant frequency pulse from the binary counter 77 passes through the NAND gate 71 to the NAND gate 72. This state will continue until FF565 is reset by a pulse appearing at the input.

In other words, after the input becomes positive, if a pulse first appears on the input, the NAND gate 7 remains active for the time until the next pulse appears on the input.
A pulse with a constant frequency appears at the output of 0, and since the output of the NAND gate 71 is "H" at this time, this pulse causes the NAND gate 72 to generate a pulse with the same frequency. Further, if a pulse appears at the input after a pulse appears at the input, a pulse at a constant frequency appears at the output of the NAND gate 72 during this period. In the former case, the relay 81 operates, and in the latter case, the relay 82 operates. Note that if a pulse appears at the input and at the same time, no pulse is generated from the NAND gate 72, and the relays 81 and 82 do not operate.

The constant frequency pulse appearing at the output of the NAND gate 72 is, for example, a 3-digit BCD counter 78.
and is counted here. The obtained three-digit digital signal is then sent to the next D/A converter 7.
9, it is converted into an analog signal. This D/A converter 79 has a function of converting the input count number of 0 to 999 into a DC voltage signal of, for example, 0 to -10V, and this voltage signal is transmitted when the contact 82a of the relay 82 is ON. Sometimes, the contact 81a of the relay 81 is turned ON as a negative voltage signal as it is.
In this case, it is inverted by the polarity conversion circuit 80 and taken out as a positive voltage signal, which is used as a signal indicating the phase difference of the ignition pulse. This operation starts after the input becomes positive, and then a reset pulse generated by the reset signal generator 73 resets FF161 and FF2.
62, FF363, FF464, FF565 and BCD
This is continued until the counter 78 is reset, and after this reset, a standby state is entered until the input becomes positive again. The input and output waveforms and timings of each part are clearly shown in the timing chart of FIG.

As described above, according to the present invention, in order to make the DC output of one thyristor amplifier follow the DC output of the other thyristor amplifier, the ignition pulse phase is followed using a constant frequency pulse obtained from a crystal oscillator. , it is possible to perform highly accurate tracking that was not possible with conventional equipment, and it is possible to configure a backup system that does not generate shocks when switching between the main control system and the backup system, allowing highly reliable phase control without interruption of operation. A controlled thyristor rectifier is obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a conventional thyristor rectifier, FIG. 2 is a circuit diagram of a general thyristor amplifier, and FIG. 3 is a block diagram showing the configuration of a thyristor rectifier according to an embodiment of the present invention. FIG. 4 is a block diagram showing another embodiment of the present invention;
FIG. 5 is a circuit diagram showing a specific configuration of the ignition phase angle difference detection device provided in the devices shown in FIGS. 3 and 4, and FIG. 6 is a time chart of signals of each part in FIG. 5. . 1... Electric motor, 2... Field coil, 3... Circuit breaker, 4... Tachometer generator, 5... Power transformer,
6... Circuit breaker, 10... Adjustment device, 19... Ignition device, 20... First thyristor amplifier, 30...
... second thyristor amplifier, 31 ... ignition device,
32...Ignition phase angle difference detection device, 33...PFM
Servo amplifier, 34...Manual setting device, 35...Motor, 36...Contact, 37...Indicator, 73...
Reset signal generator, 74, 75... Pulse circuit, 78... BCD counter, 79... D/A converter.

Claims (1)

[Claims] 1. A first thyristor amplifier that extracts a DC output from an AC power supply according to the phase of a first ignition pulse;
a second thyristor amplifier that extracts DC output from the AC power supply according to the phase of the second ignition pulse;
A setting device that sets the phase of the second ignition pulse detects the phase angle difference between the first and second ignition pulses with reference to the phase of the AC power source, and detects the phase angle difference between the first and second ignition pulses, A positive DC voltage proportional to the difference when the first firing pulse is ahead of the second firing pulse, and a positive DC voltage proportional to the difference when the first firing pulse is behind the second firing pulse. The phase angle difference detection device includes a phase angle difference detection device that generates a negative DC voltage, and an indicator that indicates the output voltage of the phase angle difference detection device, and the phase angle difference detection device is configured such that the phase angle difference detection device detects a phase angle of 0° of the phase of the AC power supply voltage. a first flip-flop that is set when the first firing pulse appears first after detection; a second flip-flop that is set when the second firing pulse first appears; and a gate circuit for passing pulses of constant frequency obtained from the crystal oscillator from the time either one of the second flip-flops is set until the appearance of the second or first firing pulse; A D/D/D/D/D converter that generates a positive DC voltage when the first flip-flop is set, and a negative DC voltage when the second flip-flop is set, according to the count number of the counter. A
A phase controlled thyristor rectifier comprising a converter. 2. Claim 1, further comprising a motor that changes the setting value of the setting device according to the polarity and magnitude of the output voltage of the phase angle difference detection device.
Phase-controlled thyristor rectifier according to section 1.