WO2015008376A1

WO2015008376A1 - Power controller and power controlling method

Info

Publication number: WO2015008376A1
Application number: PCT/JP2013/069618
Authority: WO
Inventors: 茂文後藤
Original assignee: 理化工業株式会社
Priority date: 2013-07-19
Filing date: 2013-07-19
Publication date: 2015-01-22
Also published as: KR101666768B1; CN105264731A; KR20150139614A; CN105264731B; JP6128217B2; JPWO2015008376A1

Abstract

A power controller is provided with a trigger angle determination unit (19), which determines a preliminarily-set standby trigger angle (φ_e) as a provisional control trigger angle (φˆ_n), and outputs the trigger angle (φˆ_n), when an output current monitoring unit (17) recognizes the abnormality of an output current. The trigger angle determination unit (19) determines a target trigger angle (Φ_n) calculated by an output-target trigger angle convertor (13) as a provisional control trigger angle (φˆ_n), and outputs the trigger angle (φˆ_n), when the output current monitoring unit (17) does not recognize the abnormality of the output current. A trigger-angle increment regulator (20) determines a control trigger angle (φ_n), for which a rapid increase in trigger angle has been prevented, on the basis of the provisional control trigger angle (φˆ_n) output from the trigger angle determination unit (19), and outputs the trigger angle (φ_n) to a thyristor control unit (21).

Description

Power controller and power control method

The present invention relates to a power controller and a power control method for controlling power supplied to a primary side of a transformer (transformer) having a heater connected to a secondary side.

In the power controller that controls the power supplied to the primary side of the transformer whose heater is connected to the secondary side, the timing for turning on (igniting) the thyristor connected to the primary side of the transformer is controlled. A phase control method is often used.
In such a power controller, when a large amount of power is supplied to the primary side of the transformer, the trigger angle (phase angle) indicating the timing at which the thyristor is turned on is increased, but at the start of phase control such as when the power is turned on. When the thyristor is turned on with a large trigger angle, a large inrush current flows through the transformer.

In order to prevent the occurrence of such inrush current, a method (soft start method) of gradually increasing the trigger angle by turning on the thyristor with a small trigger angle may be used at the start of phase control (for example, (See Patent Document 1).
When using the soft start method, the power supply voltage and the voltage on the primary side of the transformer are monitored, and when the voltage changes from zero to a predetermined value, the trigger angle gradually changes from a small trigger angle to the target trigger angle. To turn on the thyristor.

JP-A-6-165366

Since the conventional power controller is configured as described above, if the power supply voltage or the voltage on the primary side of the transformer is monitored and it is detected that the voltage has changed from a zero value to a predetermined value, the power controller is small. By turning on the thyristor at the trigger angle, inrush current can be prevented. However, a device for monitoring the power supply voltage and the voltage on the primary side of the transformer is required, which causes a problem that the device configuration becomes complicated.

The present invention has been made to solve the above-described problems, and can control the occurrence of inrush current without mounting a device for monitoring the power supply voltage or the voltage on the primary side of the transformer. It is an object to obtain a measuring device and a power control method.

The power controller according to the present invention is supplied to the primary side of the transformer from the target signal output from the controller that calculates the target value of the power supplied to the load connected to the secondary side of the transformer. The target trigger angle calculating means for calculating the target trigger angle indicating the timing of firing the switching element for adjusting the power to be switched, and the switching element is fired at the timing indicated by the target trigger angle calculated by the target trigger angle calculating means. The current estimation means for estimating the current flowing through the switching element, the current measurement means for measuring the current actually flowing through the switching element, and the current measured by the current measurement means is estimated by the current estimation means. If the current is smaller than the current by a predetermined value or a predetermined ratio, the abnormality recognition that identifies the abnormality of the current flowing through the switching element If the current abnormality is recognized by the means and the abnormality recognition means, the preset standby trigger angle is determined as the control trigger angle, and the control trigger angle is output and the control If an abnormality in current is not recognized by the abnormality recognition means while the trigger angle is being output, the trigger angle for control is the target trigger angle calculated by the target trigger angle calculation means from the standby trigger angle. The control trigger angle determining means for outputting the trigger angle while gradually increasing the control trigger angle until the control element reaches the trigger angle, and the switching element control means outputs the trigger output from the control trigger angle determining means. The switching element is ignited at the timing indicated by the corner.

In the power controller according to the present invention, when the control trigger angle determining means determines that the abnormality of the current is not recognized by the abnormality recognition means, the switching element with the target trigger angle calculated by the target trigger angle calculation means as the control trigger angle. This is output to the control means.

In the power controller according to the present invention, when the abnormality of the current is recognized by the abnormality recognition unit and the switching element is ignited at the standby trigger angle by the switching element control unit, the inrush current flowing through the transformer is a predetermined value. The trigger angle that is smaller than the allowable current and larger than the minimum current measurable by the current measuring means is set in the control trigger angle determining means as the standby trigger angle. .

According to the power control method of the present invention, the target trigger angle calculating means is configured to convert the transformer from a target signal output from a controller that calculates a target value of power supplied to a load connected to the secondary side of the transformer. A target trigger angle calculation processing step for calculating a target trigger angle indicating the timing of ignition of the switching element that adjusts the power supplied to the primary side, and a target estimated by the current estimation means calculated in the target trigger angle calculation processing step. When a switching element is ignited at the timing indicated by the trigger angle, a current estimation processing step for estimating a current flowing through the switching element and a current measurement unit for measuring a current actually flowing through the switching element The processing step and the abnormality recognition means are configured in advance so that the current measured in the current measurement processing step is greater than the current estimated in the current estimation processing step. When the measured value is smaller than a predetermined value or a predetermined ratio, the abnormality recognition processing step for certifying abnormality of the current flowing through the switching element and the control trigger angle determination means are recognized as abnormal in the current in the abnormality qualification processing step. If the trigger angle for standby is set as the trigger angle for control, the trigger angle for control is output, and the trigger angle for control is output, the abnormality is recognized. If no current abnormality is recognized in the processing step, the control trigger angle is gradually increased until the control trigger angle reaches the target trigger angle calculated by the target trigger angle calculation means from the standby trigger angle. And a control trigger angle determination processing step for outputting the trigger angle.

According to the present invention, it is possible to prevent the occurrence of an inrush current without mounting a device for monitoring the power supply voltage or the voltage on the primary side of the transformer.

It is a block diagram which shows the power controller by Embodiment 1 of this invention. It is a flowchart which shows the processing content in which the electric power controller by Embodiment 1 of this invention detects abnormality of an output current. It is a flowchart which shows the processing content which the electric power controller by Embodiment 1 of this invention determines the trigger angle for control. It is explanatory drawing which shows the process timing of the electric power controller when the abnormality of an output current is not detected. It is explanatory drawing which shows the process timing of a power controller when abnormality of an output current is detected. It is explanatory drawing which shows the process timing when an output current returns from abnormality to normal and a soft start begins. It is a block diagram which shows the power controller by Embodiment 2 of this invention.

Embodiment 1 FIG.
1 is a block diagram showing a power controller according to Embodiment 1 of the present invention.
In FIG. 1, a power controller 3 is connected to an AC power source 1 via a switch 2 (for example, a relay or a breaker), and supplies power from the AC power source 1 when the switch 2 is closed. In response, a thyristor 12 that is a switching element that adjusts the power supplied to the primary side of the transformer 4 by phase control is mounted. A fuse 11 is connected to the primary side of the thyristor 12.
In the first embodiment, an example in which the thyristor 12 is mounted as a switching element is shown. However, the present invention is not limited to this. For example, a triac or the like may be mounted as a switching element.

The transformer 4 is a transformer that receives power from the power controller 3 connected to the primary side and supplies power to the heater 5 connected to the secondary side.
The heater 5 as a load is a heat source for heating the controlled object 6, and a temperature sensor 7 is attached to the controlled object 6.

The temperature sensor 7 is a measuring instrument that measures the temperature of the controlled object 6 and outputs a sensor signal indicating the temperature to the temperature controller 8.
The temperature controller 8 calculates a target signal for output that matches the temperature indicated by the sensor signal output from the temperature sensor 7 with a preset target temperature, and outputs the target signal to the power controller 3. carry out.

The zero point detection unit 18 performs processing for detecting the zero point of the power supply voltage.
The output target value trigger angle conversion unit 13 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted or a one-chip microcomputer, and the thyristor 12 is turned on (point-on) from the target signal output from the temperature controller 8. The process of calculating the target trigger angle Φ _n indicating the timing of arcing is performed at every zero point detection timing.
Specifically, the output target value trigger angle conversion unit 13 includes, for example, a table indicating the correspondence between the power value and the target trigger angle Φ _{n using} the target signal output from the temperature controller 8 as the target value of power. Referring to the table, a process of outputting the target trigger angle Φ _n corresponding to the target signal is performed. The output target value trigger angle converter 13 constitutes a target trigger angle calculation unit.

The output current estimation unit 14 is composed of, for example, a semiconductor integrated circuit mounted with a CPU or a one-chip microcomputer, and the thyristor 12 is turned on at the timing of the control trigger angle output from the trigger angle increment control unit 20. In such a case, a process of calculating an estimated value Ie _nm of the output current that is a current flowing through the thyristor 12 is performed at each output current monitoring timing. The output current monitoring timing is a plurality of times during the half cycle period of the power supply cycle. In the first embodiment, the output current monitoring timing is generated every time when the half cycle period is divided into 20 equal parts. . The output current estimation unit 14 constitutes current estimation means.

The current detector 15 is composed of, for example, a CT (Current Transformer) and the like, detects a current actually flowing through the thyristor 12, and outputs a sensor signal proportional to the current.
The output current measuring unit 16 is composed of, for example, a semiconductor integrated circuit mounted with a CPU or a one-chip microcomputer, and actually flows to the thyristor 12 from the sensor signal output from the current detector 15. A process for measuring the output current _Inm , which is a current, is performed at each output current monitoring timing. The current detector 15 and the output current measuring unit 16 constitute current measuring means.

The output current monitoring unit 17 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted or a one-chip microcomputer. When the output current estimation unit Ie _nm calculated by the output current estimation unit 14 is received, predetermined coefficient estimates _{Ie nm} (e.g., 0.5) by multiplying the abnormality determination current when qualifying the abnormality of current flowing through the thyristor _{_{12 I ^ e nm (I ^}} e nm = Ie nm × predetermined The coefficient is calculated. Also, it compared the output current monitor section 17 and the abnormality determination current I ^ e _nm calculated, the output current I _nm the measured thyristor 12 by the output current measuring unit 16, the output current I _nm of the thyristor 12 is a measure Is smaller than the abnormality determination current I ^ e _nm (I _nm <I ^ e _nm ), the process for identifying the abnormality of the output current of the thyristor 12 is performed at each output current monitoring timing. The output current monitoring unit 17 constitutes an abnormality recognition unit.
Here, the output current monitoring unit 17 calculates an abnormality determination current I ^ e _nm by multiplying the estimated value Ie _nm of the output current calculated by the output current estimation unit 14 by a predetermined coefficient, and outputs the thyristor 12. When the current I _nm is smaller than the abnormality determination current I ^ e _nm (when the output current I _nm of the thyristor 12 as a measured value is smaller than the estimated value Ie _{nm of the} output current by a predetermined ratio or more), the output current of the thyristor 12 an example will be described to certify the abnormality, by adding a predetermined constant to estimate Ie _nm output current calculated by the output current estimation unit 14 abnormality determination current _{I ^ e nm (I ^ e} nm = Ie _nm + predetermined constant) and when the output current I _nm of the thyristor 12 is smaller than the abnormality determination current I ^ e _nm (the measured value of the output current I _nm of the thyristor 12 is the output current). When the current value is smaller than the estimated value Ie _nm by a predetermined value or more), an abnormality in the output current of the thyristor 12 may be recognized.

The trigger angle determination unit 19 is composed of, for example, a semiconductor integrated circuit mounted with a CPU or a one-chip microcomputer. Every time the zero point of the power supply voltage is detected by the zero point detection unit 18, the trigger angle determination unit 19 is used for temporary control. Processing for determining the trigger angle φ ^ _n is performed.
That is, when the output current monitoring unit 17 determines that the output current is normal in the first half cycle, the trigger angle determination unit 19 uses the target trigger angle Φ _n calculated by the output target value trigger angle conversion unit 13 as a temporary provision. While the control trigger angle φ ^ _n is determined, if the output current monitoring unit 17 recognizes an abnormality in the output current in the first half cycle, the preset standby trigger angle φ _e is set for the provisional control. Processing to determine the trigger angle φ ^ _n is performed.
The standby trigger angle φ _e is measured by the output current measuring unit 16 when the inrush current at the start of phase control flowing through the transformer 4 becomes smaller than a predetermined allowable current (for example, the rated current of the transformer 4). The trigger angle is greater than the minimum possible current.

The trigger angle increment control unit 20 is composed of, for example, a semiconductor integrated circuit on which a CPU is mounted, or a one-chip microcomputer, and the provisional control trigger angle φ ^ _n output from the trigger angle determination unit 19 The trigger angle φ _{n−1 of} the first half cycle is compared with a value obtained by adding a predetermined increment Δφ set in advance (φ _n−1 + Δφ), and the trigger angle φ ^ _n is compared with the added value (φ _{n −1} + Δφ), the added value (φ _n−1 + Δφ) is set as the trigger angle φ _n for control, and the added value (φ _n−1 + Δφ) is output to the thyristor control unit 21. When the trigger angle φ ^ _n is not larger than the added value (φ _n-1 + Δφ), the trigger angle φ ^ _n is set as the control trigger angle φ _n and the trigger angle φ ^ _n is set as the thyristor control unit 21. Process to output to zero point detection timing Implementation to each.
The zero point detection unit 18, the trigger angle determination unit 19, and the trigger angle increment control unit 20 constitute a control trigger angle determination means.

Thyristor control unit 21 by supplying a current to the gate of the thyristor 12 at the timing indicated by the trigger angle phi _n output from the trigger angle increment controller 20 is a control circuit for turning on the thyristor 12. The thyristor control unit 21 constitutes switching element control means.

In the example of FIG. 1, the fuse 11, the thyristor 12, the output target value trigger angle conversion unit 13, the output current estimation unit 14, the current detector 15, the output current measurement unit 16, and the output current monitoring unit, which are components of the power controller. 17, the zero point detection unit 18, the trigger angle determination unit 19, the trigger angle increment control unit 20, and the thyristor control unit 21 are assumed to be configured by dedicated hardware. A part may be composed of a computer.
For example, a part of the power controller (for example, output target value trigger angle conversion unit 13, output current estimation unit 14, output current measurement unit 16, output current monitoring unit 17, zero point detection unit 18, trigger angle determination unit 19, trigger When the angle increment control unit 20 and the thyristor control unit 21) are configured by a computer, the output target value trigger angle conversion unit 13, the output current estimation unit 14, the output current measurement unit 16, the output current monitoring unit 17, the zero point detection unit 18, A program describing the processing contents of the trigger angle determination unit 19, the trigger angle increment control unit 20, and the thyristor control unit 21 is stored in the memory of a computer, and the CPU of the computer executes the program stored in the memory. What should I do?

FIG. 2 is a flowchart showing the contents of processing in which the power controller according to Embodiment 1 of the present invention detects an abnormality in the output current, and is processed at every output current monitoring timing.
FIG. 3 is a flowchart showing the processing contents for determining the control trigger angle by the power controller according to the first embodiment of the present invention, which is processed at each zero point detection timing.
4, 5 and 6 are explanatory diagrams showing the processing timing of the power controller. In particular, FIG. 4 shows the processing timing when the output current monitoring unit 17 does not detect an abnormality in the output current, and FIG. The processing timing when an output current abnormality is detected by the output current monitoring unit 17 is shown. FIG. 6 shows the processing timing when the output current returns from normal to normal and soft start begins.

Next, the operation will be described.
The temperature sensor 7 measures the temperature of the controlled object 6 and outputs a sensor signal indicating the temperature to the temperature controller 8.
When the temperature controller 8 receives the sensor signal from the temperature sensor 7, the temperature controller 8 calculates a target signal such that the temperature indicated by the sensor signal matches a preset target temperature, and uses the target signal as the power controller 3. Output to.
For example, if the temperature controller 8 has a built-in PID controller (Proportional Integral Derivative Controller), the PID controller of the temperature controller 8 is preset with the temperature indicated by the sensor signal output from the temperature sensor 7. A deviation from the target temperature is input, PID calculation is performed on the deviation, and the calculation result is output to the power controller 3 as a target signal.

When receiving the target signal from the temperature controller 8, the output target value trigger angle conversion unit 13 calculates the target trigger angle Φ _n indicating the timing at which the thyristor 12 is turned on in the nth phase control cycle from the target signal. The target trigger angle Φ _n is output to the trigger angle determination unit 19.
For example, when the output target value trigger angle conversion unit 13 has a built-in table indicating the correspondence relationship between the target signal (target value of power) and the target trigger angle Φ _n in advance, output from the temperature controller 8 from the table. The target trigger angle Φ _n corresponding to the received target signal is read, and the target trigger angle Φ _n is output to the trigger angle determination unit 19.

In the first embodiment, when the power supply half cycle of the AC power supply 1 is a phase control cycle and the power supply frequency is 50 Hz, the power supply half cycle is 10 milliseconds, so the phase control period is 10 milliseconds.
For this reason, the output target value trigger angle conversion unit 13 calculates the target trigger angle Φ _n every 10 milliseconds. The subscript n of Φ is a variable indicating what phase control cycle it is.
4 and 5 show an example in which 51% is calculated as the target trigger angle Φ _n of the _nth phase control cycle. The 51% represents a period during which the thyristor 12 is turned on in one phase control cycle.
In the first embodiment, the control trigger angle φ _n (= target trigger angle Φ _n ) has a form in which the thyristor is turned on, and therefore, from the trigger timing to the end of the phase control cycle. The value of the angle up to the zero point. Therefore, when the control trigger angle φ _n is 51%, for example, the angle from the zero point at the start of the phase control cycle to the trigger timing is 49%.
4, 5, and 6, the angle of the first zero point position is set to 0%. Therefore, when the control trigger angle φ _n is 51%, the horizontal scale is 49% of the scale of the horizontal axis. The position is the trigger timing.

In the first embodiment, the abnormality detection process of FIG. 2 is performed every 0.5 milliseconds.
Since the phase control cycle is 10 milliseconds, the abnormality detection process of FIG. 2 is performed 19 times in total in one phase control cycle. 4 and 5, the abnormality detection process is performed at the timing of the phase angle marked with ↑ or ↓.
Hereinafter, “m” is used as a variable indicating what number abnormality detection process is in the n-th phase control cycle. m = 1, 2, 3,...
For example, when the phase angle at the zero point position at the beginning of the nth phase control cycle is 0 degree and the phase angle at the zero point position at the beginning of the n + 1th phase control cycle is 180 degrees, the phase angle of m = 1 Is 9 degrees, m = 2 has a phase angle of 18 degrees,..., M = 10 has a phase angle of 90 degrees, and m = 19 has a phase angle of 171 degrees.
When the target trigger angle Φ _n (= 51%) is expressed not in percentage but in the same manner as the above phase angle, the target trigger angle Φ _n is 88.2 degrees (= (100−51) × 180/100). )become.

In the first embodiment, the phase angle at the zero point position at the beginning of the nth phase control cycle is defined as 0 degree, and the phase angle at the zero point position at the beginning of the n + 1th phase control cycle is defined as 180 degrees. Then, the following explanation will be given.
However, this definition of the phase angle is merely an example, and the phase angle at the zero point position at the beginning of the nth phase control cycle is 180 degrees, and the phase at the zero point position at the beginning of the (n + 1) th phase control cycle. If the angle is defined as 0 degree, the phase angle of m = 1 is 171 degrees, the phase angle of m = 2 is 162 degrees,..., M = 10 is 90 degrees,. = 19, the phase angle is 9 degrees.

The output current estimation unit 14 estimates a current Ie _nm that is an instantaneous current flowing through the thyristor 12 at the timing of monitoring the mth output current in the nth phase control cycle.
Under the condition that the heater 5 is not disconnected and the transformer 4 is in a steady state, the waveform of the current (instantaneous current) that flows through the thyristor 12 is a sine wave. Therefore, the current Ie _nm that flows through the thyristor 12 is It is estimated as shown in equation (1).
Ie _nm = I _peak · sin (φ _nm ) (1)
In Equation (1), φ _nm is the phase angle (trigger angle) at the timing of monitoring the m-th output current, I _peak is the peak value of the output current when the current continues to flow for half a cycle, This is a known value calculated from the power supply voltage and the resistance value of the load.
The peak value I _peak of the output current is a square root of 2 times the effective value Irms, where Irms is the effective value of the output current when the target trigger angle is 100%.

Note that the vertical axis (current axis) of the graphs of FIGS. 4, 5, and 6 is normalized by the peak value I _peak of the output current.

The current detector 15 detects the output current (instantaneous current) of the thyristor 12 and outputs a sensor signal proportional to the output current to the output current measuring unit 16.
The output current measurement unit 16 actually flows to the thyristor 12 from the sensor signal output from the current detector 15 at the timing when the timing of the m-th abnormality detection process is reached in the n-th phase control cycle. The output current I _nm (instantaneous current), which is the current that is being calculated, is calculated (measured).

Output current monitoring unit 17, in the n-th phase control cycle, at the timing of the m-th abnormality detection process, the phase angle phi _nm at the timing, which is output from the output target value trigger angle conversion section 13 target The trigger angle Φ _n is compared, and if the phase angle φ _nm is larger than the target trigger angle Φ _n (step ST1 in FIG. 2), an abnormality detection process described later is performed.
Since the angle of the target trigger angle Φ _n (= 51%) is 88.2 degrees, the phase angle φ _nm is larger than the target trigger angle Φ _n when m = 10, 11, 12,. growing.

That is, if the phase angle φ _nm at the m-th output current monitoring timing is larger than the target trigger angle Φ _n (φ _nm > Φ _n ), the output current monitoring unit 17 causes the output current measuring unit 16 to perform the timing. The measured output current I _nm of the thyristor 12 is acquired (step ST2), the estimated value Ie _{nm of the} current flowing through the thyristor 12 estimated by the output current estimation unit 14 at that timing is acquired, and the estimated current An abnormality determination current K × Ie _nm is calculated by multiplying Ie _nm by a certain appropriate coefficient K (step ST3).
This coefficient K is a value in the range of “0 <K <1”. If the output current I _nm measured by the output current monitoring unit 17 is equal to or less than the abnormality determination current K × Ie _nm , the power supply voltage or This is a coefficient for calculating an appropriate abnormality determination current K × Ie _nm that can be determined that there is an abnormality in the load. In the first embodiment, K = 0.5 will be described.
In particular, at the output current monitoring timing of m = 10, since the phase angle is 90 degrees and is close to the target trigger angle Φ _n (88.2 degrees), the thyristor 12 generally acquired by the output current monitoring unit 17 is used. the output current I _nm can be regarded as the measurement value at the timing indicated by the target trigger angle [Phi _n.
In the first embodiment, in step ST3, the abnormality determination current 0.5 × Ie _nm calculated by the output current monitoring unit 17 is obtained when the thyristor 12 is turned on at the timing indicated by the target trigger angle Φ _n. The estimated value of the current flowing through the thyristor 12 is assumed to be 0.5 times.

Next, the output current monitoring unit 17 compares the abnormality determination current 0.5 × Ie _nm calculated in step ST3 with the output current I _nm of the thyristor 12 measured by the output current measurement unit 16 (step ST4). When the output current I _nm of the thyristor 12 is smaller than the abnormality determination current 0.5 × Ie _nm (I _nm <0.5 × Ie _nm ), the abnormality of the output current of the thyristor 12 is recognized and the output current abnormality flag is turned on. (Flag = 1) is set (step ST5).
For example, when the heater 5 connected to the secondary side of the transformer 4 is disconnected, the secondary load of the transformer 4 decreases, the output current I _nm of the thyristor 12 becomes almost 0 A, and the abnormality determination current 0.5 × Ie smaller than _nm .
Even if the switch 2 is opened or the fuse 11 is disconnected, the output current I _nm of the thyristor 12 becomes smaller than the abnormality determination current 0.5 × Ie _nm .

The trigger angle determination unit 19 executes a control trigger angle φ _n determination process every time the zero point detection unit 18 detects the zero point of the power supply voltage.
It will be specifically described below determination processing of the trigger angle phi _n for control.

When the zero point detection unit 18 detects the zero point of the power supply voltage (at the beginning of the nth phase control cycle), the trigger angle determination unit 19 detects the nth phase control cycle calculated by the output target value trigger angle conversion unit 13. The target trigger angle Φ _n is acquired (step ST11 in FIG. 3).
Next, the trigger angle determination unit 19 refers to the output current abnormality flag and confirms whether or not the output current monitoring unit 17 recognizes the output current abnormality (step ST12).
That is, if the output current abnormality flag is on (flag = 1), the trigger angle determination unit 19 determines that the abnormality of the output current is recognized, and if the output current abnormality flag is off (flag = 0). In this case, it is determined that the output current abnormality is not certified.

When the trigger angle determining unit 19 determines that the abnormality of the output current is not certified, the trigger angle determining unit 19 determines the target trigger angle Φ _n acquired from the output target value trigger angle converting unit 13 as the temporary control trigger angle φ ^ _n. The trigger angle φ ^ _n is output to the trigger angle increment control unit 20 (step ST13).
When the trigger angle determination unit 19 determines that the abnormality of the output current has been certified, the trigger angle determination unit 19 uses a preset small standby trigger angle φ _e as a temporary control trigger to prevent the occurrence of an inrush current. The angle φ ^ _n is determined, and the trigger angle φ ^ _n is output to the trigger angle increment control unit 20 (step ST14).
The standby trigger angle φ _e is a trigger angle at which the inrush current flowing through the transformer 4 is smaller than a predetermined allowable current and larger than the minimum current that can be measured by the output current measuring unit 16. (in the angle notation, 19.8 degrees) 11% as a standby trigger angle phi _e is set.

When the trigger angle increment control unit 20 receives the provisional control trigger angle φ ^ _n from the trigger angle determination unit 19, the preset upper limit value Δφ (upper limit value for increasing the trigger angle every half cycle) is set. Is compared with the trigger angle φ _n−1 for control in the first half cycle (φ _n−1 + Δφ) and the provisional control trigger angle φ ^ _n received from the trigger angle determination unit 19, It is confirmed whether or not the added value (φ _n−1 + Δφ) is larger than the provisional control trigger angle φ ^ _n received from the trigger angle determination unit 19 (step ST15).
If the added value (φ _n−1 + Δφ) is larger than the provisional control trigger angle φ ^ _n received from the trigger angle determination unit 19, the trigger angle increment control unit 20 has already completed the soft start. Therefore, to determine the trigger angle phi _n for controlling the trigger angle phi ^ _n for control of the provisional, but outputs the trigger angle phi _n thyristor control unit 21 (step ST16), the added value (phi _{n If −1} + Δφ) is smaller than the provisional control trigger angle φ ^ _n received from the trigger angle determination unit 19, the soft start has not yet been completed, so the added value (φ _n−1 + Δφ) is used as it is. It outputs to the thyristor control part 21 (step ST17).
φ _n = φ _n-1 + Δφ
Trigger angle increment control section 20 outputs a trigger angle phi _n for controlling the thyristor control unit 21 sets the output current abnormality flag to OFF (flag = 0) (step ST18).

When receiving the control trigger angle φ _n from the trigger angle increment control unit 20, the thyristor control unit 21 turns on the thyristor 12 by causing a current to flow through the gate of the thyristor 12 at the timing indicated by the trigger angle φ _n . .
In FIG. 5, in the left half cycle, although the thyristor 12 is turned on at the control trigger angle φ _n (= 51%), the output current I _nm of the thyristor 12 is the abnormality determination current 0.5 × Ie. _In this example, the output current of the thyristor 12 is recognized as abnormal because it is smaller than _nm . The trigger angle φ _n for control in the next half cycle (the right half cycle in FIG. 5) is the standby trigger angle φ _e (= 11%), and the thyristor 12 at the timing of the trigger angle φ _n (= 11%). Is turned on.
In the angle notation, the thyristor 12 is turned on at a timing of 160.2 degrees (= 180-19.8 degrees), and the thyristor 12 is turned off at a timing of 180 degrees.
In FIG. 6, when the thyristor 12 is turned on with the control trigger angle φ _{n−1 set} as the standby trigger angle φ _e (= 11%) in the previous half cycle on the left side, the output current I _n of the thyristor 12 is turned on. _{Since −1m} is larger than the abnormality determination current 0.5 × _Ien _{−1m, an} example in which the output current of the thyristor 12 is not recognized as abnormal is shown. The control trigger angle φ _n of the current half cycle (the right half cycle in FIG. 5) is the upper limit value Δφ for each half cycle with respect to the control trigger angle φ _n−1 (= 11%) of the first half cycle. (= 5%) and when a where a trigger angle phi _n for controlling the trigger angle obtained by adding ₍₌ 16%), and turns on the thyristor 12 at the timing of the trigger angle phi _{n (=} 16%).

The trigger angle determination process for control is repeatedly executed, and when the zero point detection unit 18 detects the zero point of the next power supply voltage (the beginning of the nth phase control cycle), the trigger angle determination unit 19 outputs the output target value trigger. The target trigger angle Φ _{n in the nth} phase control cycle calculated by the angle conversion unit 13 is acquired (step ST11).
Next, the trigger angle determination unit 19 refers to the output current abnormality flag and confirms whether or not the output current monitoring unit 17 recognizes the output current abnormality (step ST12).
That is, if the output current abnormality flag is on (flag = 1), the trigger angle determination unit 19 determines that the abnormality of the output current is recognized, and if the output current abnormality flag is off (flag = 0). In this case, it is determined that the output current abnormality is not certified.
However, at this stage, since the output current abnormality flag is set to OFF (flag = 0) by the trigger angle increment control unit 20 in the (n−1) th phase control cycle, the abnormality in the output current is not recognized. Judge.

Trigger angle increment controller 20, even if the abnormality of the output current is not certified, the suddenly increasing the trigger angle phi _n for control outputted previously, because the inrush current is generated, for example, about 5% A small trigger angle Δφ (about 18 degrees in angle notation) is added to the control trigger angle φ _n−1 previously output, and the addition result is determined as the control trigger angle φ _n (step ST17). .
Trigger angle increment control section 20 outputs a trigger angle phi _n for controlling the thyristor control unit 21 sets the output current abnormality flag to OFF (flag = 0) (step ST18).

When receiving the control trigger angle φ _n from the trigger angle increment control unit 20, the thyristor control unit 21 turns on the thyristor 12 by causing a current to flow through the gate of the thyristor 12 at the timing indicated by the trigger angle φ _n . .
For example, standby trigger angle phi _e is 11%, if the 5% trigger angle Δφ of the increase is because the trigger angle phi _n for control is 16%, the trigger angle phi _{n (=} 16%) At this timing, the thyristor 12 is turned on.
In the angle notation, the thyristor 12 is turned on at a timing of 151.2 degrees (= 180-19.8-9 degrees), and the thyristor 12 is turned off at a timing of 180 degrees.

As can be seen from the above description, according to the first embodiment, before the output cycle, output current if the abnormality in the output current has been certified by the monitoring unit 17, controls the standby trigger angle phi _e, which is set in advance determine the trigger angle phi _n of use, and outputs the trigger angle phi _n, before the output cycle, when the output current is not recognized as abnormal, calculated by the target output value trigger angle conversion section 13 The target trigger angle Φ _n is determined to be the temporary control trigger angle φ ^ _n and the trigger angle φ ^ _n is output. On the other hand, in the previous output cycle, the output current monitoring unit 17 recognizes an abnormality in the output current. and if determines a standby trigger angle phi _e that is set in advance in the trigger angle phi ^ _n for controlling the interim, the trigger angle determination unit 19 outputs the trigger angle phi ^ _n provided, the trigger angle increment Control unit 20 triggers Trigger angle phi ^ _n for control of the provisional output from the determination unit 19, a value obtained by adding the upper limit value Δφ increase trigger angle relative to the trigger angle phi _n-1 for control of the first half cycle (φ _n-1 If it is larger than + Δφ), the added value (φ _n−1 + Δφ) is output as a control trigger angle φ _n to the thyristor control unit 21, and the provisional control trigger angle φ ^ _n is added to the added value (φ _n-1 + Δφ), the provisional control trigger angle φ ^ _n is output to the thyristor control unit 21 as the control trigger angle φ _n , so that the primary voltage of the power supply voltage or transformer There is an effect that it is possible to prevent the occurrence of an inrush current without mounting a device for monitoring the side voltage.

In other words, according to the first embodiment, the power supply state is monitored by accrediting the disconnection of the heater 5 as a load (acknowledging an abnormality in the output current), so the power supply voltage and the voltage on the primary side of the transformer It is possible to prevent an inrush current from being generated in the transformer 4 without mounting a device for monitoring the above.
Even if the control object is the transformer 4, it is possible to prevent an inrush current from being generated in the transformer 4 when the AC power supply 1 is turned on or when an instantaneous power failure occurs. Further, even when the AC power supply 1 is continuously turned on and power is supplied only to the transformer 4, it is possible to prevent an inrush current from being generated in the transformer 4.

Further, according to the first embodiment, even when the heater 5 connected to the secondary side of the transformer 4 is disconnected and the output current of the thyristor 12 is decreased, the decrease in the output current is detected. Then, since the control trigger angle φ _{n is set} to a small standby angle (standby trigger angle φ _e ), there is a possibility that the heater 5 connected to the secondary side of the transformer 4 may be disconnected. It is also possible to prevent the generation of a certain large excitation current.
In general, in order to reduce the inrush current when the phase of the primary winding of the transformer 4 is controlled, the magnetic flux density at the rated voltage of the transformer 4 is designed to be low. In form 1, since the inrush current to the transformer 4 can be suppressed to a small value in any situation, it becomes possible to use the transformer 4 having a higher magnetic flux density than the conventional one. Miniaturization can be achieved.
Moreover, after cutting the wiring between the AC power supply 1 and the power controller 3 with the switch 2, the effect of suppressing the inrush current when reconnected with the switch 2 can be expected.

Embodiment 2. FIG.
In the first embodiment, an example in which the heater 5 is connected to the secondary side of the transformer 4 is shown. As shown in FIG. 7, for example, the heater 5 is connected via a switch 30 such as a relay or a breaker. 5 may be connected to the secondary side of the transformer 4.
In this case, when the switch 30 is open, the power controller 3 detects a decrease in the output current of the thyristor 12 as in the first embodiment, and sets the control trigger angle φ _n to the standby state. In order to reduce the trigger angle (standby trigger angle φ _e ), it is possible to prevent the generation of a large excitation current that may be caused by the opening / closing operation of the switch 30 connected to the secondary side of the transformer 4.
The processing content itself of the power controller 3 is the same as that in the first embodiment.

1 AC power supply, 2 switch, 3 power controller, 4 transformer (transformer), 5 heater, 6 controlled object, 7 temperature sensor, 8 temperature controller, 11 fuse, 12 thyristor (switching element), 13 output target Value trigger angle conversion unit (target trigger angle calculation means), 14 output current estimation unit (current estimation means), 15 current detector (current measurement means), 16 output current measurement unit (current measurement means), 17 output current monitoring unit (Abnormality recognition means), 18 zero point detection part (control trigger angle determination means), 19 trigger angle determination part (control trigger angle determination means), 20 trigger angle increment control part (control trigger angle determination means), 21 thyristor Control unit (switching element control means), 30 switch.

Claims

Points of the switching element for adjusting the power supplied to the primary side of the transformer from the target signal output from the controller for calculating the target value of the power supplied to the load connected to the secondary side of the transformer Target trigger angle calculating means for calculating a target trigger angle indicating the timing of the arc;
Current estimating means for estimating a current flowing through the switching element when the switching element is ignited at a timing indicated by the target trigger angle calculated by the target trigger angle calculating means;
Current measuring means for measuring a current actually flowing through the switching element;
An abnormality that qualifies an abnormality of the current flowing through the switching element when the current measured by the current measuring unit is smaller than a current estimated by the current estimating unit by a predetermined value or a predetermined ratio. Authorization means,
When a current abnormality is recognized by the abnormality recognition means, a preset standby trigger angle is determined as a control trigger angle, the control trigger angle is output, and the control trigger If a current abnormality is no longer recognized by the abnormality recognition means in the state of outputting a corner, the control trigger angle is calculated from the standby trigger angle by the target trigger angle calculation means calculated by the target trigger angle calculation means. Until reaching the control trigger angle determining means for outputting the trigger angle while gradually increasing the control trigger angle,
A switching element control means for igniting the switching element at a timing indicated by the trigger angle output from the control trigger angle determination means.
The control trigger angle determination means outputs the target trigger angle calculated by the target trigger angle calculation means to the switching element control means as a control trigger angle when no abnormality of current is recognized by the abnormality recognition means. The power controller according to claim 1.
In the control trigger angle determining means, when the abnormality is recognized by the abnormality recognition means and the switching element is ignited at the standby trigger angle by the switching element control means, The trigger angle at which a flowing inrush current becomes smaller than a predetermined allowable current and becomes larger than a minimum current measurable by the current measuring means is set as the standby trigger angle. Item 1. The power controller according to Item 1.
The power supplied to the primary side of the transformer from the target signal output from the controller for calculating the target value of the power supplied to the load connected to the secondary side of the transformer by the target trigger angle calculating means A target trigger angle calculation processing step for calculating a target trigger angle indicating the timing of ignition of the switching element for adjusting
A current estimation processing step for estimating a current flowing through the switching element when the switching element is ignited at a timing indicated by the target trigger angle calculated in the target trigger angle calculation processing step;
A current measuring step in which a current measuring means measures a current actually flowing through the switching element;
The abnormality recognition means flows to the switching element when the current measured in the current measurement processing step is smaller than a current estimated in the current estimation processing step by a predetermined value or a predetermined ratio. Anomaly certification processing step to authorize current anomalies;
When the control trigger angle determining means determines that the current abnormality is recognized in the abnormality recognition processing step, the control trigger angle is determined as a control trigger angle, and the control trigger angle is set as the control trigger angle. And outputting the control trigger angle, and if the current abnormality is not recognized in the abnormality recognition processing step, the control trigger angle is changed from the standby trigger angle to the target trigger. A control trigger angle determination processing step for outputting the trigger angle while gradually increasing the control trigger angle until the target trigger angle calculated by the angle calculation means is reached;
And a switching element control processing step in which the switching element control means ignites the switching element at a timing indicated by the trigger angle output in the control trigger angle determination processing step.