JP3341196B2 - Three-phase power regulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase power regulator.

[0002]

BACKGROUND OF THE INVENTION As is well known, a power regulator adjusts the amount of power supplied to a load by inserting a switching element on a power supply line and changing the on-time of the switching element. The ignition control of the switching element is performed by generating a triangular wave (sawtooth wave) based on a power supply signal, comparing the triangular wave with a command signal (DC), and using a pulse having a duty ratio according to the command signal. Like that. That is, for example, when the switching element is fired based on the rising edge of the pulse, the firing timing changes according to (the elapsed time from the zero cross of the AC signal), that is, the command value.
Therefore, the period during which the switching element is on varies, and the amount of power supply per unit time varies.

In the case of a three-phase power regulator to which the present invention is applied, the above-described switching elements are inserted into the power supply lines of each phase of UVW, and each switching element is fired at an appropriate timing based on a command value. I am trying to do it. In order to supply power stably, it is ideal that the ignition timings of these three switching elements are shifted by 120 degrees, and that the ON times are equal.

[0004] As the switching element,
Generally, a triac is used for a single-phase power regulator, and a mixed-arm bridge is used for a three-phase power regulator, in which a thyristor and a diode are connected in parallel with their forward directions reversed.

When three-phase power adjustment is attempted using a single-phase power regulator using a triac in order to use common components, three such single-phase power regulators are provided, and U, V , W phase to a neutral point, for example, from a Y-Y connected transformer, apply the extracted signal (power signal) to each single-phase power regulator, and perform the above-described control processing after the generation of the triangular wave. It is conceivable to do so.

However, although the use of a triac simplifies the control, at least two triacs must be turned on at the same time in order to flow a current. On the other hand, the firing pulse is 0 when the power signal crosses zero.
become. Accordingly, since the phases of the respective power signals are shifted by 120 degrees, when the firing angle command value exceeds 120 degrees, two triacs cannot be turned on at the same time, and as a result, the control range of the phase angle becomes 0. ~ 120 degrees. In addition, when the output exceeds 120 degrees, the output suddenly becomes zero, so that the characteristics are poor and control at a low voltage cannot be performed.

As a result, it is difficult to use the single-phase power regulator as it is for the three-phase power regulator, and it is necessary to use a different switching element as in the prior art, and the storage and management are complicated. Etc. Also, for the user side, for example, when a single-phase power regulator is used, if the subsequent change in environment causes the single-phase power regulator to be abolished and the need to switch to a three-phase power regulator arises, Therefore, the conventional single-phase power regulator is wasted. Therefore, development of an adjuster capable of increasing the controllable range to 120 degrees or more while using a triac and easily performing control at a low voltage is under way.

On the other hand, the conventional three-phase power regulator described above
Broadly speaking, there are analog and digital systems. In the former analog method, a Y-Y connection is made to the power supply line.
Two transformers are inserted, via which the voltages U, V, W for the neutral point are obtained. Each power signal (UV
W), a triangular wave generation circuit and a comparator are connected in series, and the same command value is given to each comparator. Then, the output (triangular wave) of the triangular wave generation circuit is given to the comparator, and when the value exceeds the command value, the switching element is turned on (ON).

The triangular wave generating circuit generates a triangular wave by forming a rectangular wave from the three voltage signals (sine waves) via a comparator and passing the signal through a charge / discharge circuit. Therefore, since the triangular wave rises accurately from the zero-cross point of the power signal of each phase, if the inclination of the triangular wave of each phase is equal, the firing timing is shifted by exactly 120 degrees according to the phase delay of each power signal. Will be

The latter digital method is disclosed in
As disclosed in JP-A-106879 and JP-A-61-15565, a single CPU generates three-phase firing signals. After detecting a zero cross in place of a triangular wave generating circuit in an analog system, a predetermined signal is generated. Means for calculating the phase angle by counting the number is provided. Then, when the phase angle corresponding to the command value is reached, each corresponding switching element is fired. And, to detect the zero cross point, a transformer is installed on the power line,
The output voltage of each phase of the transformer is A / D converted, and each process is performed based on the converted digital value.

In the case of the analog system, a transformer for three phases is required, and a triangular wave generating circuit and a comparator are required for each phase, which results in an increase in the number of parts and an increase in size and cost. Furthermore, the characteristics of each element constituting the charge / discharge circuit when forming a triangular wave vary, and the slope of the triangular wave in each phase differs, and the time from zero crossing to firing (firing timing) varies in each phase. It has shifted,
It becomes impossible to fire at intervals of 120 degrees, and stable driving becomes difficult.

On the other hand, in the case of the digital method, it takes more than 100 μsec to read data (8 bi
(t, 20 MHz), for example, when a power supply frequency of 50 Hz is used, only 100 divisions can be performed in a half cycle. As a result, there is a limit to the improvement of the resolution, and the detection of the zero cross and the control of the ignition timing of each phase can only obtain the accuracy within the above range. As described above, both the analog type and the digital type have advantages and disadvantages.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to solve the above-described problem and to control the ignition angle command at 120 ° or more while using a triac as a switching element. And to provide a three-phase power regulator capable of performing stable control at low voltage. Furthermore, while achieving the above-mentioned object, high-resolution, accurate zero-crossing can be detected, the ignition timing of each phase is shifted by 120 degrees, stable driving can be performed, the size is small, the calorific value is small, and the command value and It is another object to provide a three-phase power regulator that has a proportional output and is inexpensive.

[0014]

In order to achieve the above object, a three-phase power regulator according to the present invention controls the firing angle of a triac mounted on a power supply line from a three-phase power supply to a load. The three-phase power regulator performs zero-cross detection based on a power signal flowing through the power line .
A reference wave that rises et, from the firing angle command value given point, means for generating a reference pulse including a pulse width corresponding to the firing angle command value, the firing angle command value of at least 120
A pulse correction means for delaying a fall of the generated reference pulse when the temperature exceeds the degree, and a means for firing the triac based on an output of the pulse correction means . And the pulse correction means
During the zero-crossing of the power signal.
Turn on the ACK and play multiple triacs at the same time
The period was set to be sufficient for turning on.

Further, any two of the three-phase power supply lines
An analog single-phase controller that generates a reference pulse signal serving as a reference for the ignition signal of each phase based on the inter-phase voltage of each phase, and a phase angle of 120 degrees by digital processing with respect to the output of the single-phase controller. Firing signal generating means for generating a firing signal for each phase by delaying, and a driving means for firing a triac mounted on each of the power supply lines based on the firing signal received from the firing signal generating means. And wherein the single-phase controller further comprises pulse correction means for delaying the fall of the generated reference pulse when the firing angle command value is at least 120 degrees or more , wherein the pulse correction means delays Period
The triac is maintained even after the zero crossing of the power signal.
Turn on, and turn on multiple triacs simultaneously
It may be in a period of time sufficient der so that in order to.

Preferably, the ignition signal generating means includes a shift register for storing the L / H state of the reference signal and shifting stored information at a predetermined timing, and a desired output terminal of the shift register. It is preferable to generate an ignition signal based on the output from the control circuit, and to use the output of the shift register as a control signal as to whether or not to perform the delay processing by the pulse correction means.

Further, the pulse correction means includes a CR charge / discharge circuit, and switches a time constant of the CR charge / discharge circuit based on a control signal given when a predetermined phase angle has elapsed from the zero crossing, and It is even better to delay the fall.

The firing angle for determining whether or not to perform the delay processing for delaying the fall of the reference pulse by the pulse correction means is preferably larger than 90 degrees and smaller than 120 degrees. Done . Ie,
This is because, if the operation is performed at less than 90 degrees, when the firing angle command value is small, the rising of the next pulse may overlap and the three triacs may be turned on at the same time, and the operation becomes unstable. If the angle is larger than 120 degrees, two triacs will not be turned on at 120 degrees at the same time if the correction processing is not performed, so that it is useless even if the delay processing is performed. To ensure that the delay (correction) process is performed stably and reliably, it is better to start from an angle as early as possible.

[0019]

When the firing angle command value is equal to or smaller than the predetermined angle, the pulse correction means does not operate (no delay / extension processing is performed). Therefore, a predetermined triac is turned on based on the reference pulse, and the falling ( The arc is automatically extinguished when the instantaneous value of the voltage is zero due to zero crossing. Therefore, the three-phase power regulator operates with a simple control system that only controls the firing time. Then, since a plurality of triacs need to be turned on at the same time, control is performed for a firing angle command value of 0 to 120 degrees as it is.

Further, the firing angle command value is set to a predetermined angle (120
When the temperature becomes equal to or more than the above , the pulse correction means operates and the fall of the reference pulse is extended. Therefore, the triac is maintained in the on state even if the zero cross occurs, and power can be supplied to the load. Therefore, power control can be performed when the firing angle command is 120 degrees or more.

According to the second aspect of the present invention, the single-phase controller generates a reference pulse signal serving as a source of a firing signal based on an arbitrary inter-phase voltage. At this time, since the signal is processed by analog processing, the zero crossing of the inter-phase voltage is accurately detected. After the zero-cross, the reference wave rising based on the inter-phase voltage signal is compared with a command value, and an ON signal is output when the reference wave exceeds the command value. This is the reference pulse.

On the basis of the reference pulse or, if necessary, a signal which has undergone a fall delay process by the pulse correcting means, the firing signal generating means generates a firing signal for the triacs installed in each phase. Generate. In other words, the power signal of a certain phase from the zero crossing of the inter-phase voltage is 3
The power signal is delayed by 0 degrees, and the power signals of the remaining two phases are shifted by ± 120 degrees with respect to the power signal. Therefore, when the reference signal is turned on, the ignition signal is output when the phase is shifted by a predetermined phase angle. Then, the ignition signal of each phase is digitally processed based on the same reference signal and output with a delay of a predetermined phase angle, so that the ignition timing of each phase is accurately shifted by 120 degrees.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a three-phase power regulator according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention. As shown in FIG.
VW), power is supplied to the three-phase load 11 via the triacs 10a to 10c.

Any two of the three phases (U-phase, V-phase in this example)
A single-phase controller 20 is attached to the interphase voltage (extracted by the power supply device 12) of the phase, and a reference signal (reference pulse (correction pulse) serving as a reference for generating an ignition signal for the triacs 10a to 10c therein. Yes / no correction)) and sends it to the next-stage firing signal generator 30.

In the ignition signal generating section 30, the triacs 10a to 10a to
Generate a respective firing signal for 10c. As a result, the phases of the generated ignition signals are shifted by 120 degrees.

The output of the ignition signal generating section 30 is applied to an ignition signal output section 40, which receives an ignition signal (trigger pulse) supplied from the ignition signal generating section 30 and outputs the actual triacs 10a to 10c. An ON signal is given to the gate. Then, the firing signal generating section 30 and the firing signal output section 40 constitute "means for firing the triac based on the output of the pulse correcting means" in the present invention.

Next, each part will be described in detail. First, as shown in FIG. 2, a power supply device 12 for extracting an inter-phase voltage includes a transformer 12a connected between two phases of a power supply line, and a full-wave rectifier (diode bridge) 12b connected to a secondary side of the transformer 12a. And a switching regulator 12c connected to two terminals of the full-wave rectifier 12b. As a result, when a sine wave is input to the primary side of the transformer 12a as shown in the figure, the sine wave is reduced to a logic level by the transformer 12a and corresponds to the magnitude synchronized with the input waveform (the timing of zero crossing coincides). A full-wave rectified waveform (see FIG. 3) is output from the other two terminals of the full-wave rectifier 12b.

The single-phase controller 20 includes a zero-cross detection circuit 21 disposed on the input side, a reference wave generation unit 22 which receives an output of the detection circuit 21 and generates a substantially triangular reference waveform, and a reference wave generation unit The comparator 23 includes a comparator 23 that compares an output voltage of the comparator 22 with a command value given from the outside and generates a reference pulse, and a pulse correction circuit 24 that corrects an output (reference pulse) of the comparator 23.

As shown in FIG. 2, the zero-cross detecting circuit 21 includes a zener diode 21a and a comparator 21b.
The full-wave rectified waveform (in FIG. 3) is shifted downward by the Zener diode 21a (see FIG. 3), and the waveform is applied to the inverting input terminal of the comparator 21b. In the comparator 21b, since the non-inverting input terminal is grounded, the output of the comparator 21b becomes H when the shifted voltage becomes negative. Therefore, a rectangular wave (pulse) is output near the zero-crossing of the UV interphase voltage (see FIG. 3).

As shown in FIG. 4, the reference wave generator 22
A switch 22a composed of a transistor is provided on the input side,
A switch 22b is inserted between the inverting input terminal of the comparator 22b and the ground. A non-inverting input terminal of the comparator 22b has a predetermined voltage V1 obtained by dividing the power supply voltage Vcc by voltage dividing means including two series resistors.
Is given as a reference voltage. And comparator 2
The output of 2b is provided to the charging circuit 22c, and the output of the charging circuit 22c is fed back to the inverting input terminal of the comparator 22b via a predetermined feedback loop.

The charging circuit 22c includes two capacitors C
1, C2 and the three resistors R1 to R3 are connected in series and parallel as appropriate, and the two capacitors C1, C
2 is provided with a transistor Tr1 capable of short-circuiting both ends of the capacitor C2 on the ground side.

Therefore, when the zero-cross signal output from the zero-cross detection circuit 21 changes from H to L, the input-side transistor 22a is turned off (the switch is opened),
The voltage of the inverting input terminal of the comparator 22b (initially 0 when switched to L) is compared with the reference voltage V1. Accordingly, the output of the comparator 22b becomes H, so that the transistor Tr1 of the charging circuit 22c is turned on, and the capacitor C2 is short-circuited. Therefore, the charging circuit 22c is configured as shown in FIG.
(A), the power supply voltage Vcc becomes
The capacitor C1 is charged by a time constant determined by RC. As a result, the output voltage of the charging circuit 22c gradually increases.

As the output voltage increases, the voltage at the inverting input terminal of the comparator 22b also increases (t0 in FIG. 6).
To t1). This rising curve is almost proportional to a change in the output voltage of the charging circuit 22c. When a certain time has elapsed from the zero cross, the comparator 22b
(The voltage fed back from the charging circuit 22c) exceeds the reference voltage V1.
Then, the output of the comparator 22b becomes L, so that the transistor Tr1 of the charging circuit 22c is turned off, and both terminals of the capacitor C2 are opened.

As a result, the charging circuit 22c operates as shown in FIG.
Since the equivalent circuit as shown in (B) is obtained and the time constant changes, the rate of change (increase) of the output voltage of the charging circuit 22c also changes (increases). Therefore, as shown in FIG. 6A, the voltage (after t1) of the inverting input terminal of the comparator 22b sharply rises.

Then, when the power supply signal crosses zero, a pulse signal is input to the gate of the transistor constituting the switch 22a, the switch 22a is once turned on, and the inverting input of the comparator 22b also goes to ground, so that it becomes zero. Thereafter, by repeating the above processing,
A reference wave close to a sine wave as shown in FIG. 6A is output every time the power supply signal crosses zero. Then, such a waveform becomes the output of the reference wave generation circuit 22 as it is and is given to the comparator 23.

In the comparator 23, as described above, a comparison is made with the command value (voltage converted from 4 to 20 mA) corresponding to the firing angle command value. Becomes H. Therefore,
The reference wave rises after the power signal of the inter-phase voltage crosses zero and rises to the next zero cross, and becomes a substantially triangular wave shape. Therefore, the higher the command value, the higher the pulse is turned on (H).
The time (elapsed time from the zero crossing) is slow and the pulse is turned off (L) in the next zero crossing, so that the higher the command value is, the shorter the pulse (reference pulse) is output. (See FIG. 6B).

In this embodiment, the charging characteristic (shape of the reference wave) is thus made non-linear and approximate to a sin curve, so that the relationship between the command value and the output voltage is as shown in FIG. 7 (A). Then, it becomes almost linear.

When a conventionally used triangular wave is used as a reference wave, the relationship between the command value and the output is a cos curve, as shown in FIG.
In the case of a simple charging circuit using CR (there is no switching midway as in the above-described embodiment), the relationship between the command value and the output is an S-shaped curve as shown in FIG. In each case, the output voltage becomes non-linear, and the linearity is lower than that in the present embodiment. The linearity is the worst when a triangular wave is used. However, considering the circuit configuration, it is easiest to use a triangular wave, and this embodiment is the most complicated. Therefore, in the present invention, which of the above three is adopted as the reference wave, a desired one can be used in consideration of required accuracy and the like. In this example, the zero-cross detection circuit 21, the reference waveform generation circuit 22, and the comparator 23
Means for generating a reference pulse.

The pulse correction circuit 24 determines that the firing angle command is 12
It is intended to enable firing even at 0 degrees or more (generating multiple triacs that are turned on at the same time).
When the power supply signal crosses zero, the reference pulse falls, but the fall is delayed for a certain time. However, even when the firing angle command is smaller than 90 degrees, if the fall of the pulse is delayed as described above, there is a problem that the rising of the reference pulse based on the next firing signal overlaps. When it is less than the degree, the delay processing is not performed.

FIG. 8 shows a specific configuration. As shown in FIG.
The output of the comparator 23 is connected to the RC charge / discharge circuit 24a via diodes D1 and D2 connected in series in the forward and reverse directions. The contact point between the two diodes D1 and D2 is electrically connected to the power supply voltage Vcc. RC charge / discharge circuit 2
The output of 4a is connected to a comparator 24b. The comparator 24b compares the output with a predetermined reference voltage Vc obtained by dividing the power supply voltage Vcc. When the output is higher than the reference voltage Vc, H (pulse on) is output. L is output.

Further, the above-mentioned contact is connected to the transistor Tr.
2 is connected to the ground through the transistor Tr2.
The output of the zero-crossing detection circuit 21 is connected to the gate of the transistor Tr.
2 is also turned on and the contact is conducted to ground.

Further, the output of the RC charge / discharge circuit 24a is
The transistor Tr3 is connected to the ground via a resistor R3 and a transistor Tr3. The transistor Tr3 is set to be turned on when the phase after the zero crossing is delayed by 90 degrees.

Next, the principle of operation of the pulse correction circuit 24 will be described. As described above, the output of the comparator 23 (input to the pulse correction circuit (RC charging / discharging circuit 24a) 24) has two types of on / off (H / L) based on the magnitude relationship between the command value and the reference wave. The RC charge / discharge circuit 24
The output (contact point) of “a” has two types based on ON / OFF of the transistor Tr3, that is, connected to the ground via the resistor R5 and opened to the ground.

Accordingly, the patterns can be classified into four patterns based on the combination of the above-described conditions.
FIG. 9A to FIG.
(D) is obtained. That is, first, FIG.
Indicates a case where the input (output of the comparator 23) is H and the transistor Tr3 is off. As shown in the figure, since both ends of the diode D1 are both H, the contact becomes H, and the current supplied from the power supply voltage Vcc charges the capacitor C3 with a certain time constant ("Charge 1").

In this state, the input (comparator 23)
Is low, the current from the power supply voltage Vcc flows through the diode D1, so that the contact is also low. The equivalent circuit at that time is as shown in FIG. 7B, and the charge charged in the capacitor C self-discharges in the RC charge / discharge circuit 24a as indicated by the arrow in the figure ("discharge 1"). The above two operations are applied up to 90 degrees after the zero cross.

On the other hand, when the transistor Tr3 is turned on, the contact becomes conductive with the ground via the resistor R3, so that when the input (output of the comparator 23) is H, the state becomes as shown in FIG. When the charge falls to L, the state becomes as shown in FIG. The operation at this time is the same as in the cases of FIGS. 7A and 7B, but the time required for charging and discharging changes because the time constant changes because the resistor R3 is connected in parallel. Then, the above two operations are applied up to 90 degrees or more after the zero cross and up to a predetermined angle (120 + α degrees) described later.

As shown in FIG. 10, when the ignition command angle is less than 90 degrees, the input (output of the comparator 23) is turned on before 90 degrees as shown in FIG. 10 (FIG. 10A). , Charging 1 (charging based on the equivalent circuit of FIG. 9A). Therefore, as shown in FIG. 10C, the output (contact point) of the RC charge / discharge circuit 24a is
When the signal rises with a delay according to a predetermined time constant and becomes equal to or higher than the reference voltage (contact voltage value) of the comparator 24b at the subsequent stage, the output of the comparator 24b, that is, the output of the pulse correction circuit 24 also becomes H. By setting the time constant appropriately as shown in the figure, the signal rises almost without delay with respect to the rise of the input (FIG. 2A). After 90 degrees have passed, charging 2 (FIG. 9)
(Charging based on the equivalent circuit of (C)).
Since the capacitor C is already fully charged, the result remains unchanged.

For the same reason, when the signal falls, it operates according to the discharge 1, and falls almost simultaneously with the fall of the input (reference pulse). Therefore, a pulse signal substantially the same as the output of the comparator 23 (slightly delayed)
Is the pulse correction circuit 24, that is, the single-phase controller 2
0 is output as an output signal.

On the other hand, when the firing command angle is 90 degrees or more,
The time chart is as shown in FIG. That is,
The input (the output of the comparator 23) is 9
When 0 degree elapses, the equivalent circuit of FIG. 9C or 9D is obtained. Therefore, when the input is turned on thereafter, the circuit operates according to the charge 2 and rises almost simultaneously. On the other hand, when the input is turned off, the charge stored in the capacitor C is gradually discharged in accordance with the discharge 2, so that the voltage value of the output (contact point) of the RC charge / discharge circuit 24a also gradually decreases, and the input (reference pulse) ) Falls below the reference voltage (contact point) after a lapse of a fixed time, and the output of the comparator 24b is turned off. Therefore, as shown in the figure, the pulse width is extended by a certain time as compared with the reference pulse, and the pulse width from the zero crossing to
Even after the lapse of 0 degrees, the output of the single-phase controller 20 remains on for a certain period of time.

When the firing angle command value is used as a parameter, the value of R with respect to the input signal (output of the comparator 23) is
The output of the C charge / discharge circuit 24a (broken line) and the final output of the pulse correction circuit 24 (solid line) are as shown in FIGS. 12A and 12B. Maintain the ON state.

By the way, if this pulse extension process is repeatedly performed, the RC charge / discharge circuit
Since 4a is not discharged instantaneously, the voltage between the terminals of the capacitor C keeps H for a certain time. The contact between the diodes D1 and D2 also remains at H, and although it is originally discharge 2, the state becomes charge 2 and eventually there is a possibility that it will be always on.

Therefore, in this embodiment, in order to reliably drop the contact to L at the time of a zero cross (when 180 degrees have elapsed from the previous zero cross), the detection signal of the zero cross detection circuit 21 is received as described above, and the contact is connected to the contact. The turned-on transistor Tr2 is turned on. Thus, during the extension (delay) processing, the state becomes the discharge 2 and the apparatus operates normally.

As shown in FIG. 1, the firing signal generating section 30 includes a shift register 31 serving as a storage element, a clock generating circuit 32 for generating a clock signal for operating the shift register 31, and a predetermined signal of the shift register 31. In accordance with the on / off state of the output terminal of the first terminal is suppressed from turning on only one triac (when turned on, a predetermined 2
Output logic circuit 33 for generating and outputting a predetermined trigger signal so that one or all of the triacs are turned on)
And a waveform shaping circuit 34 that receives the output of the output logic circuit 33 and generates an ignition signal.

The shift register 31 is of a 16-bit (8 bits × 2) type, and each time a clock signal is input from the clock generation circuit 32 one pulse at a time, a reference signal (for the reference pulse) supplied from the single-phase controller 20 is applied. , And the state (H / L) of the pulse signal with the pulse width extension corrected or the signal without the correction is sequentially captured, and the previously captured information is shifted one by one. Here, when the reference signal is on, it becomes H.

The shift timing of the shift register 31, that is, the clock frequency is adjusted so that the timing at which the phase changes by 10 degrees and the shift timing are synchronized. Specifically, when the frequency is 50 Hz, (1/50) × (10/360) = 0.55, and the clock may be generated every 0.55 msec. Although not shown, the clock generation circuit 32 that generates the clock has a basic configuration including a crystal oscillator and a counter, and divides the oscillation frequency of the crystal by the counter so as to output a pulse having a desired frequency. Has become.

The outputs of the third, ninth, and fifteenth bits of the shift register 31 are respectively expressed by U
The control rectangular wave signals u, w, and v for the phase, W phase, and V phase were used.

Therefore, each output u,
w and v indicate that the control rectangular wave signal u turns on with a delay of 30 degrees after the single-phase reference signal is turned on, the control rectangular wave signal w turns on with a delay of 90 degrees, and a control rectangular wave signal with a delay of 150 degrees. The rectangular wave signal v turns on. The ON period is the same as the pulse width of the single-phase reference signal. As a result, a rectangular wave obtained by shifting the single-phase reference signal by 30, 90 and 120 degrees is obtained from each output terminal.

This is done for the following reason.
First, as shown in FIG. 13, u is set to 30 degrees because the UV phase entering the power supply circuit is advanced by 30 degrees with respect to the U phase. In other words, the time when the reference wave generated based on the UV phase exceeds the command value by 30 degrees corresponds to the time when the U-phase power signal actually exceeds the command value. Further, since the V phase is shifted by 120 degrees with respect to the U phase, “30 + 12”
A time of 150 degrees behind "0" corresponds to a time when the V-phase power signal actually exceeds the command value. Since the W phase is further shifted by 120 degrees, based on the above formula for calculating the V phase, 27
The shift point is 0 degrees (30 + 240). In this case, a shift register having at least 27 bits or more is required, and the memory capacity is increased. Therefore, in the present embodiment, 90 degrees (= 270-1), which is the inverted phase of 270 degrees.
The control is performed by using (80) to reduce the memory.

As an example of the operation of the shift register 31, as shown in FIG. 14 (A), the state of a certain timing (initial value for convenience) is determined by the output terminals 1 to 10 of the shift register 31. It is assumed that the bits up to the bit are H, and these 10 bits are when the reference signal is on (pulse width). Then, each time a clock is input, the data is shifted by one bit. Then, each output terminal (control rectangular wave signals u, w,
The state of v) is as shown in FIG.

As described above, the shift register 31
Connects the output terminals of 30, 90 and 150 degrees to the output logic circuit 33, so that the terminal pins of 90 degrees are originally in use. Therefore, in this embodiment, the 90-degree output terminal of the shift register 31 is connected to the pulse correction circuit 2 described above.
4 is connected to the base of the transistor Tr3, and the shift register is used as a control signal source for indicating 90 degrees. Accordingly, the number of parts can be reduced, and the transistor Tr3 can be accurately turned on / off at 90 degrees, thereby improving the accuracy. In addition,
In the present invention, a control signal generation source such as a timer for notifying 90 degrees may be mounted separately from the shift register.

The output logic circuit 33 outputs the state (H) of each control rectangular wave signal output from the shift register 31.
/ L) based on the actual triacs 10a to 10c
A gate signal is generated which is a timing for generating a firing signal for turning on the switch. That is, as shown in FIG.
In order to supply power to the Y-connected three-phase load 11, it is necessary to turn on at least two or more elements. By the way, when looking at FIG. 14, at the time of the clock (1, 2), u, w
Is H, the corresponding triacs 10a, 10c
Is turned on, a current flows between UW as shown in FIG. However, at the time of the clock (3, 4), only w is H
Therefore, even if only the corresponding triac 10c is turned on, no current flows (the operation is correct in this state). However, if the other triac 10a or 10b is ignited and turned on due to noise or the like, a current may flow.
, Power is supplied more than necessary, and phase control cannot be performed correctly. Therefore, in the output logic circuit 33, the triac is turned on only when two or more control rectangular wave signals are at H level, so that stable driving is ensured.

More specifically, this is implemented by a logic circuit as shown in FIG. Thus, for example, if the control rectangular wave signals u, v, w are as shown in FIG. 17, each of the gates U,
V and W are all L, and the gates whose corresponding control rectangular wave signals are H are H otherwise. And
The time when each of the gates U, V, W switches from L to H is the firing timing for the corresponding triac 10a to 10c.

The waveform shaping circuit 34 is a circuit in which a trigger pulse having a short pulse width is output when each of the gates changes from L to H, and the L state is maintained thereafter. Timing (gate is L to H
Only when the switch is made, the ignition signal is ensured to be generated.

More specifically, as shown in FIG. 18, a differentiating circuit 34a and a Schmitt trigger circuit 34b are provided, and an inverted signal of the gate signal is supplied to the differentiating circuit 34a. Detects the time when the signal changes from H to H, and generates a trigger pulse. By providing the differentiating circuit 34a in this way, a trigger pulse is output only when there is a sudden change such as changing from L to H. So that the firing signal is not output. Then, the Schmitt trigger circuit 34b outputs the trigger pulse as a single rectangular wave having a short pulse width. This rectangular wave becomes a firing signal (see FIG. 19).

As described above, in this example, since at least two gates are turned on, the command value (phase angle) is in the range of 0 to 120 + α degrees (α is a pulse correction circuit). 24 (corresponding to the delay time in FIG. 24). That is, if it exceeds 120 + α degrees, u, v, w
This is because there is no place where a plurality of gate signals (trigger pulses) are simultaneously turned on. And ideally 150
Control to a degree is possible.

The drive circuit 40 receives the ignition signal and drives the triacs 10a to 10c. As shown in FIG. 20, the drive circuit 40 includes a transistor serving as a switch 41 on the input side, and connects the power supply voltage Vcc to the ground. The switch 41 and the phototriac coupler 42 connected in series are arranged. The triacs 10a to 10c to be controlled are connected to the light receiving side of the phototriac coupler 42. Thus, when the ignition signal is received, the switch 4
Since the transistor constituting 1 is turned on, the switch is closed and a current flows through the phototriac coupler 42 to emit light. Upon receiving the light emission, the light receiving side is also turned on, the power supply and the load are conducted through the phototriac coupler 42, and the power is supplied, whereby the triac 10a is fired.

In the drawing, reference numeral 43 denotes a snubber circuit composed of an RC series circuit, and reference numeral 44 denotes a varistor. Since the configuration of the drive circuit 40 can be the same as that of the conventional drive circuit, detailed description will be omitted. Further, the drive circuit 40 having the above configuration is connected to each of the triacs 10a to 10c and fires at a predetermined timing (shifted by 120 degrees).

Then, as described above, the drive circuit 40
Turns on the predetermined triacs 10a to 10c in accordance with the ignition signal output from the waveform shaping circuit 34, and the ignition signal is generated when the ignition angle command value exceeds 90 degrees by the pulse correction circuit 24. Indicates that the interval in which a plurality of triacs can be turned on is 0 to 120 + α degrees (when correction is not performed,
0 degree), so that the controllable section is extended and controllable even at a low voltage.

Further, in this embodiment, since the zero-cross of the power signal is detected by the analog system using the zero-cross detecting circuit 21, it is possible to detect the zero-cross accurately without any error based on the sampling time, which is a disadvantage of the digital system. Further, based on one inter-phase voltage (between UV in this example), a digital circuit such as the shift register 31 generates a firing timing for a triac inserted into each power supply line, so that each triac 10a to 10c Can be accurately shifted by 120 degrees.

Next, using the above-described embodiment, the firing timing (firing angle command value) is 0 degree (delay phase from Xerox (the same applies hereinafter)), 30 degrees, 60 degrees, 90 degrees, 120 degrees,
The waveform of each phase U, V, W at 130 degrees and 140 degrees,
The relationship between the UV inter-phase voltage and the output voltage RS is shown in FIGS. The trigger pulse shown in the lower part of each figure is the output (the control rectangular wave signal u, v, w) from the shift register 31 described above.

As is clear from FIG. 21, when the firing angle command value is 0 degrees, all the gate signals are always ON, so that the U, V and W phases are always supplied to the three-phase load. (The corresponding triac is fired at the same time as the zero crossing of each power signal), so that it is synchronized with the UV interphase voltage,
A beautiful sine wave is output. Then, as the firing command values increase, the time from zero crossing to firing becomes longer, and there is no power supply to the load during that time. Therefore, the output voltage RS becomes the sine Wave (U
V), the waveform becomes distorted, and the power supply amount also decreases (FIGS. 22 to 24).

When the firing angle command value reaches 120 degrees, it exceeds 90 degrees, so that the delay processing by the pulse correction circuit 24 operates. Therefore, as shown in FIG.
Even when it reaches 0 degrees, the period during which the trigger is on without being turned off is extended by about 20 degrees. Accordingly, two triggers are turned on during the extended period, so that two triacs are turned on, and the output voltage RS is generated for a short period. In this case, when the firing angle command value is 130 degrees, the on-time is further shortened, but power can be supplied slightly according to the same operation principle (see FIG. 26).

When the firing angle command value becomes 140 degrees, a plurality of triggers are not turned on at the same time, and each gate is always turned off, so that the output voltage RS becomes zero. The relationship between the firing angle command value and the output voltage decreases almost linearly as shown in FIG.
It becomes zero at 0 degrees. It should be noted that although control up to 150 degrees is theoretically possible, the two triacs must be turned on at the same time, that is, in order that the sections in which the triggers for each phase are on overlap, some margin may be required. And stable control was performed up to about 140 degrees as described above.

In the above-described embodiment, an example is shown in which the present invention is applied to a three-phase power regulator having a new configuration in which the analog system and the digital system are combined, but the present invention is not limited to this. It can also be applied to other three-phase power regulators (those using a triac as a switching element).

FIG. 29 shows an example. That is, the figure is an example applied to an analog type. In the case of an analog type, as shown in FIG.
From the V and W phases, a signal for a neutral point is extracted from, for example, a Y-Y connected transformer 50, and the extracted signal (power signal) is supplied to three single-phase power regulators 51 each using a single-phase triac. give. The same firing angle command value is set in each of the three single-phase power regulators 51.
At a predetermined firing angle, the built-in triac 51a is fired,
Power is supplied to the load by a predetermined angle.

Then, each single-phase power regulator 51 generates a triangular wave (sawtooth wave) using the zero-cross detection circuit 51b and the reference wave generation circuit 51c based on the power supply signal, as shown in FIG. The comparator 51d compares the triangular wave with the command signal (DC), and generates a pulse having a duty ratio according to the command signal. Such a configuration is the same as a conventional ordinary single-phase power regulator. In the present invention, the output of the comparator 51d is connected to the pulse correction circuit 5d.
1e, the signal is supplied to the triac 51a via the gate pulse amplifier 51f.

The pulse correction circuit 51e extends and delays the fall of the reference pulse when the firing angle command value is larger than 90 degrees. The specific circuit configuration is as follows.
For example, as shown in FIG. As is clear from the drawing, the pulse correction circuit 51e has basically the same configuration as the pulse correction circuit 24 in the above-described embodiment. Then, the transistor Tr3 for controlling and determining whether or not to extend the pulse is turned on / off by the output of the delay element 51g. As the delay element 51g, for example, a timer can be used, and the pulse correction circuit is driven by a 90-degree output command to start delay. Note that the specific operation principle of this circuit is the same as that of the above-described embodiment, and a detailed description thereof will be omitted. The gate pulse amplifier 51f corresponds to the drive circuit 40 in the above-described embodiment.

With this configuration, the triac 51a whose operation is controlled by each single-phase power regulator 51 is
Since the on state can be maintained even when the angle exceeds 180 degrees, the state in which a plurality of triacs are simultaneously turned on becomes zero.
１２０120 + α degrees, and the controllable angle range is widened by α degrees corresponding to the delay amount.

[0079]

As described above, in the three-phase power regulator according to the present invention, the fall of the reference pulse can be extended by the pulse correction means. There can be turned on a plurality of the triac at the same time 120 degrees or more. As described above, since the firing angle control of 120 degrees or more is enabled, stable control at a low voltage can be performed. Since a three-phase power regulator can be configured using a triac generally used as a single-phase power regulator, the devices can be shared and the cost can be reduced.

Further, in the case of the configuration according to claim 2, the zero cross can be detected accurately with high resolution, the ignition timing of each phase is shifted by 120 degrees, stable driving can be performed, and the size and heat generation amount are small. Can be reduced.

That is, since a reference signal is generated based on an arbitrary two-phase voltage, only one transformer is required.
The calorific value can be suppressed. Since the single-phase control that outputs the reference signal from the detection of the zero cross to the shaping of the reference wave and the comparison with the command value is configured by an analog circuit, the zero cross can be detected accurately.

The firing signal for actually firing the triac is formed by performing digital processing on one reference signal generated by the analog method and shifting the reference signal by a predetermined angle. The arc timing is exactly 1
It shifts by 20 degrees.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a three-phase power regulator according to the present invention.

FIG. 2 is a diagram showing an internal configuration of a power supply device and a zero-cross detector.

FIG. 3 is a diagram illustrating an operation principle of the zero detection circuit.

FIG. 4 is a diagram illustrating a circuit configuration of a reference wave generation unit.

FIG. 5 is a diagram illustrating an operation principle of a charging circuit in a reference wave generation unit.

FIG. 6 is a diagram illustrating output characteristics of a reference wave generation unit.

FIG. 7 is a diagram illustrating an operation of a modification of the reference wave generation unit.

FIG. 8 is a diagram illustrating a circuit configuration of a pulse correction circuit.

FIG. 9 is a diagram illustrating an operation principle of an RC charge / discharge circuit in the pulse correction circuit.

FIG. 10 is a time chart illustrating an operation of the pulse correction circuit.

FIG. 11 is a time chart illustrating an operation of the pulse correction circuit.

FIG. 12 is a waveform diagram illustrating the operation of the pulse correction circuit.

FIG. 13 is a diagram illustrating a correlation between phase differences of power supply signals.

FIG. 14 is a timing chart illustrating the operation principle of a shift register.

FIG. 15 is a diagram illustrating a state of power supply to a three-phase load.

FIG. 16 is a diagram showing an internal configuration of an output logic circuit.

FIG. 17 is a timing chart showing an example of the operation of the output logic circuit.

FIG. 18 is a diagram showing an internal configuration of a waveform shaping circuit.

FIG. 19 is a timing chart illustrating the operation of the waveform shaping circuit.

FIG. 20 is a diagram showing an internal configuration of a drive circuit.

FIG. 21 is a diagram showing the state of each waveform when the firing angle command is 0 degrees.

FIG. 22 is a diagram showing a state of each waveform when a firing angle command is 30 degrees.

FIG. 23 is a diagram showing a state of each waveform when the firing angle command is 60 degrees.

FIG. 24 is a diagram showing the state of each waveform when the firing angle command is 90 degrees.

FIG. 25 is a diagram showing a state of each waveform when a firing angle command is 120 degrees.

FIG. 26 is a diagram showing a state of each waveform when a firing angle command is 130 degrees.

FIG. 27 is a diagram showing the state of each waveform when the firing angle command is 140 degrees.

FIG. 28 is a diagram illustrating a relationship between an output voltage and each firing command according to the present embodiment.

FIG. 29 is a diagram showing another embodiment of the three-phase power regulator according to the present invention.

FIG. 30 is a circuit diagram showing an internal configuration of the pulse correction circuit.

[Explanation of symbols]

 10a to 10c Triac 11 Three-phase load 20 Single-phase controller 21 Zero-cross detection circuit 22 Reference wave shaping circuit 23 Comparator 24 Pulse correction circuit 30 Firing signal generation circuit 31 Shift register (storage element) 40 Drive circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-194546 (JP, A) JP-A-59-106879 (JP, A) JP-A-61-15565 (JP, A) 14546 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02M 1/08 321

Claims (4)

(57) [Claims] 1. A three-phase power regulator for controlling a firing angle of a triac mounted on a power line from a three-phase power supply to a load, wherein the three-phase power conditioner is detected based on a power signal flowing through the power line.
Reference wave rising from zero cross and given firing angle finger
Means for generating a reference pulse having a pulse width corresponding to the firing angle command value from the command value, and delaying the fall of the generated reference pulse when the firing angle command value is at least 120 degrees or more. A pulse correction unit for causing the triac to ignite based on an output of the pulse correction unit.
Keep the triac on even after signal zero crossing.
To turn on multiple triacs at the same time
A three-phase power conditioner characterized by a sufficient period . 2. An analog single-phase controller for generating a reference pulse serving as a reference for an ignition signal of each phase based on an inter-phase voltage of any two phases of a three-phase power line, and the single-phase controller. A firing signal generating means for generating a firing signal for each phase by delaying a phase angle by 120 degrees by digital processing with respect to the output of the power supply, and each of the power supplies based on the firing signal received from the firing signal generating means. Drive means for igniting a triac mounted on the line, and wherein the single-phase controller has a small ignition angle command value.
When more than 120 degrees even without further comprises a pulse correction means for delaying the falling edge of the generated reference pulse, a period for delaying by said pulse correction means, the power supply
Keep the triac on even after signal zero crossing.
To turn on multiple triacs at the same time
A three-phase power conditioner characterized by a sufficient period . 3. The ignition signal generating means includes a shift register which stores an L / H state of an output signal from the pulse correction means and shifts stored information at a predetermined timing. A fire signal is generated based on an output from a desired output terminal, and an output of the shift register is used as a control signal as to whether or not to perform delay processing by the pulse correction means. Item 3. The three-phase power regulator according to Item 2. 4. The pulse correction means includes a CR charge / discharge circuit capable of switching a time constant, and the time constant of the CR charge / discharge circuit is determined based on a control signal given when a predetermined phase angle has elapsed from a zero cross. The three-phase power regulator according to any one of claims 1 to 3, wherein the three-phase power regulator is switched to delay the fall of the reference pulse.