JP3478812B2 - Load voltage control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for controlling a load to be controlled by voltage driving, and more particularly to a load voltage control method suitable for precisely controlling a voltage applied to the load.

[0002]

2. Description of the Related Art For example, in controlling a fan motor for controlling an intake amount of a combustion control device, a proportional valve for controlling a fuel flow rate, a fan motor for ventilating a bathroom and other rooms, etc. In particular, recently, it has been required to control the applied voltage to the controlled load with high accuracy. As a specific example, looking at the air volume control in the combustion equipment, considering the voltage applied to the fan motor and the rotation speed at that time, the voltage-rotation speed control function when the air quantity reaches a predetermined air quantity A system for controlling the amount to be constant (for example, JP-A-2000-346434 and JP-A-57-118916).
No.)

[0003]

In this conventional method, the voltage actually applied to the fan motor is detected, but for this reason, the deviation of the voltage due to the circuit error of the voltage detection unit mounted in the control device is avoided. Therefore, it is necessary to adjust the voltage detection unit, and it is indispensable to adjust the detection voltage by using a potentiometer or the like. Of course, it is necessary for the drive unit to also be able to output a highly accurate voltage output. For that purpose, linearity, that is, accuracy that is the same between low voltage output and high voltage output, is important. In many cases, this cannot be satisfied with such a circuit, and if this is the case, the circuit part here may need to be adjusted with a volume or the like. In most cases, however, increasing the linearity without compromising the complexity of the circuit is often impossible due to cost constraints.

As described above, in the conventional air volume control device, although the predetermined air flow rate can be maintained, the manufacturing cost is reduced because the drive unit is complicated or the adjustment process is required at the manufacturing stage. Increase. Not only the air volume control device but also any type of load voltage control device is exposed to the demand for simplification and cost reduction of each device used, and generally faces similar problems.

The present invention has been made in view of the above points, and even if there is an output voltage error due to a circuit error of a control circuit with respect to the above-mentioned fan motor and various voltage control type loads to be controlled. As a result, for the load,
It is intended to provide a method capable of applying a voltage with high accuracy.

[0006]

In order to achieve the above object, the present invention provides a specified value from a control circuit for voltage-controlling a load to be controlled of a voltage control type in a stage before shipment of a control device, for example, a manufacturing stage. The applied voltage that is actually applied to the load when the control data is output is measured externally by the load voltage control device, and is measured by a highly accurate external voltage measuring device that is temporarily connected to the control circuit. The measured measured applied voltage value is transmitted to the control circuit and stored in the non-volatile storage means connected to the control circuit. Compare the design applied voltage value that should theoretically be applied to the load when the control data of the above specified value is output from the control circuit, and the actual measured applied voltage value stored in the nonvolatile storage means. However, under actual operation of the load voltage control device, the value of the control data output from the control circuit is corrected in consideration of the difference.

Basically, the main idea of the present invention is as described above, but as described in the claims of the present application, as the configuration further specified in the present invention, the measurement is performed by the external voltage measuring device as described above. At this time, the control circuit outputs a plurality of control data of different values to make a plurality of measurement points, and the design applied voltage value and the actual measured applied voltage value at each measurement point are stored in the non-volatile storage means, and the load is stored. Under actual operation of the voltage control device, in consideration of the difference between the measured applied voltage value at the measurement point having a value close to the control data output from the control circuit at that time and the design applied voltage value as the comparison target, the control circuit It is proposed to correct the control data output by.

This idea is changed a little, and in order to improve the accuracy even in the middle between the measurement points, in the actual operation of the load voltage control device, based on the difference between the respective adjacent measurement points, the adjacent measurement points are measured. The expected change in the voltage change between points is calculated, and the control data output by the control circuit is corrected in consideration of the difference appropriate for the control data output from the control circuit. Can be configured.

The number of control data or measurement points having different values output from the control circuit at the time of measurement using the external voltage measuring device is preferably three or more, and is the minimum. Shall be near the minimum value of the actual voltage width of the applied voltage applied to the load, the maximum shall be the maximum voltage value that can be output from the control circuit or a value in the vicinity thereof, and the other shall be an appropriate value in between. Is good. of course,
Since various information at each measurement point is stored in the non-volatile storage means, by using a rewritable non-volatile storage means, depending on the product or subsequent design specification changes, various information about those measurement points, That is, the control data at the measurement point, the design applied voltage to be theoretically output, the actually measured measured applied voltage, the difference, etc. can be arbitrarily changed even afterward. This means that, after all, the modification of the measurement point itself is optional as needed.

Further, in the above configuration, instead of storing the design applied voltage value and the measured applied voltage value in the non-volatile storage means, the difference may be calculated in advance and the difference may be stored. In addition to storing the correction coefficient obtained on the basis of the control data, if the control data is generally an N-bit digital value, the control data is 1 / N of 2
Since it has a resolution of, the actual voltage change width per unit resolution (1 bit) is calculated according to the difference, and the ratio value (weight) to be multiplied by the digital value which is the control data at that time is a correction coefficient. It may be stored as. In either case, as a result, the control data is corrected in view of the above difference. If necessary, the difference per bit may be calculated and stored in the non-volatile storage means for use.

In addition to the above configuration, preferably, when the measured applied voltage is sent to the control circuit, it is compared with the maximum value of the voltage error that should be allowed with respect to the design applied voltage value, and if it deviates from it. It is convenient to configure the alarm device to issue an alarm as a circuit failure of the control circuit. Of course, at this time, it is not necessary to store the measured applied voltage value or to calculate and store the difference or ratio value. Of course, comparing the maximum value of the voltage error with the difference is the same as determining whether the measured applied voltage value exceeds the allowable upper limit value or falls below the allowable lower limit value. The allowable voltage error maximum value or the upper limit value and the lower limit value allowed for the measured applied voltage may be stored in advance in the non-volatile storage means.

When the control circuit generally includes a microcomputer, the number of bits of control data may not be so large due to the cost. In order to deal with this and improve the control accuracy resolution in the first place, the following method is also effective. That is, the control data corresponding to the design applied voltage value to be output at that time is output with one cycle of outputting the corresponding output digital value as one output cycle and m consecutive times as one control cycle. And Then, the output digital value in the output cycle of 0 to m-1 of the m output cycles is selectively increased by +1.
If it is configured so that it can be stepped, the effective resolution is m
Can be doubled.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows an example of a voltage control device for a controlled load configured by applying the present invention. In the illustrated case, a controlled load 21 forces a combustion unit (not shown) to supply an air amount corresponding to the combustion amount. It is a fan motor 21 for rotating a fan that supplies air. However, as described in advance, the present invention can be applied to any control target load 21 as long as it is a voltage control type.

In this case, it is assumed that the control circuit 18 for controlling the voltage applied to the fan motor 21, which is a load, also controls the entire combustion equipment. However, in the following, the parts related to the present invention will be described. I will explain only. This control circuit 18
Determines the voltage to be applied to the fan motor 21 so that the optimum fan motor rotation speed is obtained according to the combustion amount at each time, and outputs the control data for outputting the voltage to the constant voltage drive circuit 15. send. The control data may be a general N-bit binary numerical value, or may be an electric signal in which a digital value is replaced with a pulse width, such as one according to PWM (pulse width modulation), or a digital value. It may be a frequency modulation signal or the like in which is replaced with the frequency. Also,
Before being sent to the constant voltage drive circuit 15, it may be sent as an analog value corresponding to the digital value output from the control circuit 18 by a D / A converter (not shown). Constant voltage drive circuit
According to the existing technology, 15 has a circuit configuration corresponding to these.

In the constant voltage drive circuit 15, the control circuit 18 has a load 21.
The switching transistor 12 is turned on and off at a cycle (pulse width) determined at each time so that the output voltage to the load 21 intended to be applied to the fan motor driving DC power supply 11 is generated. When the transistor 13 is on, it flows into the capacitor in the smoothing circuit 14, and when it is off, it flows out.
When viewed on an average on the time axis, the applied voltage applied to the fan motor 21 is also a considerably stable voltage. As is the case with each of the following circuits, the control circuit 18 can generally be substantially realized by a microcomputer (hereinafter simply referred to as a microcomputer), and is inserted between the microcomputer 18 and an external circuit as needed. The interface used is not shown. Those skilled in the art can use any necessary interface.

On the other hand, the voltage actually applied to the fan motor 21 from time to time is detected by the voltage detection circuit 16 and fed back to the constant voltage drive circuit 15, and the fan motor is also driven.
The actual rotation speed of 21 is the rotation speed detection circuit (rotation speed sensor) 17
Is detected by and returned to the microcomputer 18. In this way, feedback control is performed to obtain the number of rotations of the fan motor 21 required at each time, and the voltage applied to the fan motor 21 is feedback controlled.

However, as described above, the voltage detection circuit 16 incorporated in the control device is often inevitably a simple circuit due to cost constraints, and the detection accuracy is often too high. Therefore, even if the feedback control system itself can function with high accuracy, the voltage applied to the fan motor 21 cannot be controlled with high accuracy because the accuracy of the input value is not high in the first place.

Therefore, in the present invention, the following method is adopted. First, an external voltage measuring device 23 is prepared at a stage before shipment of the control device, for example, at a manufacturing stage. Since this is not built into the control device, a high precision one can be used. There are already many commercially available high-accuracy voltage measuring instruments 23 having a detection voltage output section or interface suitable for sending data to the microcomputer 18. Any means may be used for communication from the measuring device 23 to the microcomputer and is not limited.

If this measuring device 23 is connected, a control circuit
The control data of the specified value is output from 18, the applied voltage actually applied to the load 21 at this time is measured by the measuring instrument 23, and the measured applied voltage value is transmitted to the control circuit 18 for control. It is stored in the non-volatile storage means 22 connected to the circuit 18. For example, the prescribed value output from the control circuit at this time is set to a value that causes the control apparatus to output the designed maximum voltage value Vmax (Dsgn), as shown in FIG.

In such a case, since there is a loss in general, the measured applied voltage value Vmax (Real) measured by the voltage measuring device 23 which is actually applied to the fan motor 21 and is preferably as accurate as possible is slightly It is often low. This value Vmax (Real) is stored in the non-volatile storage means 22, but the error ER between the two is also higher than the lower voltage range, generally the maximum error ERmax. On the other hand, the voltage range actually applied to the fan motor under actual operation does not use the entire voltage range that can be output from the device, and the minimum value Vu-min of the actual use voltage range Vrange is not zero but the maximum value. Vu-max is also lower than the maximum value Vmax (Dsgn) designed to be output from the control device. Speaking of concrete values, for example, the control device uses the maximum value Vmax (Dsg
Even if n) is designed to be 35V, the applied voltage applied to the fan motor 21 is from the minimum Vu-min = 8V to the maximum Vu-max = 35V.

However, under actual operation of the control device according to the present invention, the difference which is the maximum error between the measured applied voltage value Vmax (Real) and the design specification value Vmax (Dsgn) stored in advance in the non-volatile storage means 22. Based on the above, the control circuit 18 corrects the value of the control data output from time to time. For example, in the measurement mode using the external voltage measuring device 23, the control device actually outputs the fan motor 21 according to the control data that should output the maximum output voltage Vmax (Dsgn) = 35V issued from the control circuit.
If the voltage value applied to is 34V, the error is 1V.
The ratio is 34/35 = 0.97 (rough value). Therefore, when, for example, 20 V should be output to the fan motor 21 under actual operation, the control circuit 18 can generate control data for outputting 20.4 V, which is 1.02 times 20 V, using the reciprocal of the ratio as a correction coefficient. Correct it. Of course, the measured applied voltage Vmax (Real) may be higher, but the correction method in that case is the same as the method.

Actually, however, the maximum output voltage Vmax (Dsg
The error in the voltage range below the maximum error ERmax in n) does not always show a direct change. In other words, if there is an error of 1V at the maximum output voltage of 35V, half of that is 1
The error may not be exactly 0.5V at 7.5V. The linearity of the difference or ratio or the correction factor may not always be guaranteed. On the other hand, the lower the voltage value applied to the fan motor 21, the higher the accuracy required in many cases.

In view of this, the present invention further proposes that the control circuit 18 output a plurality of control data having mutually different values to make a plurality of measurement points when measuring with the external voltage measuring device 23. There is. That is,
The design applied voltage value and the actual measured applied voltage value at each measurement point are stored in the non-volatile storage means 22, and under actual operation of the device, the measurement point having a value close to the control data output from the control circuit 18 at that time. The control data output from the control circuit is corrected based on the difference between the measured applied voltage value in (1) and the design applied voltage value that is the comparison target. For example, in FIG. 2, the control data generated by the control circuit when outputting the maximum output voltage, which is the first measurement point, is the output digital value Bn-ma.
If x, the same measurement is performed at arbitrary measurement points Bn-a and Bn-b in the voltage value range below that, and the respective design applied voltage values and measured applied voltage values are stored in the non-volatile storage means 22. I will let you. If the value close to the control data output from the control circuit 18 at each moment is the output digital value Bn-a, the difference between the design applied voltage value taken for the value Bn-a and the actually measured measured applied voltage value. If the value is close to Bn-b, the error will be minimized if the correction is based on the difference between the design applied voltage value taken for this and the actually measured measured applied voltage value. The voltage can be suppressed to the limit, and highly accurate voltage control becomes possible.

This can be further developed to the work of extracting the change in the difference, aiming at higher accuracy. That is, the design applied voltage value and the actual measured applied voltage value at each of the measurement points Bn-a, Bn-b, and Bn-max are stored in the non-volatile storage means, and are adjacent to each other when the load voltage control device is in operation. Measurement points Bn-a, Bn-b: Based on the difference between the differences in Bn-b, Bn-max, between the adjacent measurement points Bn-a to Bn-
b: The change of the expected difference in the voltage change of Bn-b to Bn-max is obtained, and the control data output by the control circuit is taken into consideration in view of the difference suitable for the control data with respect to the control data output at that time by the control circuit. Correct the data. For example, when the maximum output voltage is output at the measurement point Bn-max, it is assumed that the measured applied voltage is only 0.9 times the expected output voltage as a result of the measurement. If the ratio of this difference is always constant, the control circuit 18 may output corrected control data such that the output voltage is the reciprocal multiple of any voltage value. However, for example, it can be considered that the measurement point Bn-max is 0.9 times as described above, but the measurement point Bn-a is only 0.8 times. In such a case, the change amount of the difference between the adjacent measurement points Bn-b to Bn-max is extracted, and based on this, for any voltage,
It is good to get the optimal difference. For example, using simple linear interpolation, the difference in output voltage between Bn-b and Bn-max is 10V, and the difference (difference in change rate) is from 0.8 times as described above.
If the difference is 0.9 times 0.1, the difference (ratio value) should be calculated to increase 0.01 times for each 1V increase. Although a more complicated one may be used as the interpolated ratio value measurement curve, linear interpolation is generally sufficient.

Here, the number of control data (the number of measurement points) of different values output from the control circuit 18 at the time of measurement using the external voltage measuring device 23 is as shown in FIG.
It is desirable to set at least three or more, and the minimum measurement point (Bn-a) is near the minimum value Vu-min of the actual use voltage range Vrange of the applied voltage applied to the load 21, and the maximum measurement point (Bn-a). -max) is a maximum voltage value Vmax (Dsgn) that can be output from the control circuit 18 or a value in the vicinity thereof as described above, and other values are preferably intermediate values. In particular, from the viewpoint of performing highly accurate correction in a small range of the applied voltage to the fan motor 21 that requires fine accuracy, at a place close to the minimum value Vu-min of the actual applied voltage width Vrange of the load applied voltage. The pre-measurement of and the above correction based on it is valid. Of course, these measurement points or various information obtained there, that is, the design applied voltage to be theoretically output at the measurement point, the actually measured measured applied voltage, the difference, etc. are rewritten in the nonvolatile storage means 22. By using what is possible,
Since it can be changed arbitrarily, subsequent product changes at a later date,
It is possible to immediately respond to changes in design specifications.

As is apparent from the above description, instead of storing the applied voltage value measured by the measuring device 23 in the non-volatile storage means 22, a difference from the design applied voltage value is calculated in advance, and this difference is calculated. Of course, it may be stored or a correction coefficient obtained based on the difference may be stored. As a general rule, the correction method that takes into consideration the difference is adopted.

Further, when the control data is an N-bit digital value Bn, as is usual when a microcomputer is used for the control circuit 18, instead of storing the measured applied voltage value in the non-volatile storage means, The actual voltage change width per control data unit resolution is calculated, and the ratio value that should be multiplied by the digital value that is the control data at that time under actual operation of the load voltage control device is stored as a correction coefficient, and based on this, You may make a correction. In other words, consider the case where the control data is given 8-bit resolution on the microcomputer side, that is, 255 steps of resolution. In this case, if the maximum output voltage Vmax (Dsgn) that can be output is 25.5V for simplicity of explanation, the voltage change width is 0.1V per step. In such a case, for example, if the measured applied voltage Vmax (Real) actually measured in the measurement mode is 22.5V,
Actually, the voltage is only 0.9 times higher than expected. Therefore, the reciprocal of the error ratio, which is 1.11 times, is used as the correction coefficient to perform the correction under actual operation. For example, when the control data should output a digital value corresponding to 100 steps, the output corresponding to 111 steps is actually output. Digital value
Output Bn. Of course, as described above, if the error information is picked up in advance at some measurement points, the correction is performed in consideration of the error information (difference) at the place close to the digital value that should be actually output at that time. To do

However, when the above-mentioned error in the measurement mode is too large, it may be better to suspect an initial failure of the control circuit 18 beyond the problem of correction. Therefore, when the applied voltage measured by the external voltage measuring device 23 is sent to the control circuit 18, it is compared with the maximum voltage error that should be allowed for the design applied voltage value, and if it deviates from it, Alternatively, when the measured applied voltage value exceeds the allowable upper limit value or falls below the allowable lower limit value, it is convenient to configure the alarm device 19 to issue an alarm as a circuit failure of the control circuit 18. The alert may be visible, audible, or both.
Of course, at this time, it is not necessary to store the measured applied voltage value or to calculate and store the difference or ratio value. Comparing the maximum value of the voltage error with the difference is the same as determining whether the measured applied voltage value exceeds the allowable upper limit value or falls below the allowable lower limit value, and therefore the determination may be made accordingly. Then, the allowable voltage error maximum value or the upper limit value and the lower limit value allowed for the measured applied voltage may be stored in the non-volatile storage means 22 in advance.

The principle of the present invention has been described above.
In addition to this, it is possible to present a device for substantially improving the resolution itself of the control data. As mentioned above,
Even when the control data is defined by the digital value Bn, the number of bits is not so large and is often limited to about 8 bits due to the cost constraint. The resolution is 2 8 = 256-1 = 255 steps. However, when aiming for high-accuracy voltage control, there are many cases where this is completely insufficient.

In such a case, the method shown in FIG. 3 is effective. When the control data is an N-bit digital value as described above, the control data corresponding to the design applied voltage value that the control circuit 18 should output at that time is a cycle in which the corresponding output digital value Bn is output once. Is output as one output cycle ts, and the continuous m times are output as one control cycle tc. In the case of the figure, 4 output cycles are 1 control cycle
FIG. 3 shows a case where tc is shown, and as an example, a waveform subjected to pulse width modulation (PWM) is shown, and a pulse Pwa having a pulse width corresponding to the output digital value Bn = x is shown in FIG.
In the case of (A), it is output in all of the output cycles ts. Therefore, the average value of the output digital value in this one control cycle tc is Bn = x, and the average pulse width is
It is the pulse width of Pwa itself. Here, Bn = x means a digital value corresponding to the number of steps x.

In contrast to the case where all the pulses have the same pulse width Pwa, in FIG. 3 (B), the output digital value Bn is Bn = x only once in the four output periods ts. Different,
Bn = x + 1. A pulse having a pulse width corresponding to this is indicated by reference symbol Pwb. In such a case, when viewed in one control cycle tc, the average value is Bn = x + 0.25, whereas Bn = x in the case of FIG. 3 (A). The pulse width is also equal to widened by a quarter. Similarly, when the output digital value is incremented by 1 in the two output cycles ts as shown in FIG. 3 (C), the average output digital value becomes Bn = x + 0.5, and as shown in FIG. 3 (D). When three times are set, the average output digital value is Bn = x
It becomes +0.75. That is, generally speaking, by configuring so that the output digital value in the output cycle of 0 times to m−1 times in the output cycle ts of m times can be selectively stepped by +1, The resolution can be improved m times. Of course, m is, in principle, any positive integer of 2 or more.

In the actual circuit, when the modulated pulse waveform is output by the PWM function as the hardware function of the microcomputer 18, the PWM output is connected to the port having the interrupt function of the microcomputer to operate the microcomputer. By synchronizing the PWM operating in a cycle different from that of the software with the software, the output value can be made variable for each cycle of the PWM output for the above purpose.

[0033]

According to the present invention, highly accurate voltage control is possible even if an inexpensive and simple circuit configuration is adopted in the control device for controlling the voltage controlled load. Also, according to a particular aspect of the present invention, the resolution of the output data in the control circuit can be substantially improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a voltage control device applied to a fan motor to which the present invention is applied.

FIG. 2 is an explanatory diagram illustrating a method of correcting an output voltage from a control circuit in the present invention.

FIG. 3 is an explanatory diagram of a method of substantially improving the control resolution of the control circuit.

[Explanation of symbols]

11 DC power supply 15 Constant voltage drive circuit 16 Voltage detection circuit 17 Speed detection circuit 18 Control circuit (microcomputer) 21 Fan motor (Voltage control type load) 22 Non-volatile storage means 23 External voltage measuring device

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Claims (8)

(57) [Claims] 1. A load voltage control method for controlling a voltage applied to a voltage control type load, wherein a plurality of different values are provided from a control circuit for voltage controlling the load before the load voltage control device is shipped. Control data is output to make a plurality of measurement points, and the applied voltage actually applied to the load at each of the measurement points is provided outside the load voltage control device, and is temporarily stored in the control circuit. A non-volatile memory connected to the control circuit by transmitting the design applied voltage value at each measurement point and the measured actual measured applied voltage value measured by an external voltage measuring device connected to the control circuit. While being stored in the means, when the load voltage control device is in actual operation, an upper value at the measurement point of a value close to the control data output from the control circuit at each time. Load voltage control method comprising; measurement applied voltage and in view of the difference between the design applied voltage value becomes the comparison target, to correct the control data output of the control circuit. 2. A load voltage control method for controlling a voltage applied to a voltage control type load, wherein a plurality of different values are provided from a control circuit for voltage controlling the load before the load voltage control device is shipped. Control data is output to make a plurality of measurement points, and the applied voltage actually applied to the load at each of the measurement points is provided outside the load voltage control device, and is temporarily stored in the control circuit. A non-volatile memory connected to the control circuit by transmitting the design applied voltage value at each measurement point and the measured actual measured applied voltage value measured by an external voltage measuring device connected to the control circuit. While stored in the means; under actual operation of the load voltage control device, the measured applied voltage value at each measurement point and the design applied as a comparison target. Based on the difference between the adjacent measurement points of the difference with the pressure value, the change in the expected difference in the voltage change between the adjacent measurement points is obtained, and the control data at that time output by the control circuit is calculated. On the other hand, in consideration of the difference suitable for the control data, the control data output from the control circuit is corrected. 3. The load voltage control method according to claim 1, wherein the number of control data or the number of measurement points of different values output from the control circuit when the external voltage measuring device is used is The load voltage control method is characterized by being three or more; 4. The load voltage control method according to claim 1, 2, or 3, wherein the design applied voltage value and the measured applied voltage value are stored in the non-volatile storage means instead of the difference in advance. And storing this difference; a load voltage control method comprising: 5. The voltage control method according to claim 4, wherein instead of storing the difference in the nonvolatile storage means, a correction coefficient obtained based on the difference is stored. And a load voltage control method. 6. The load voltage control method according to claim 1, wherein the measured applied voltage value is stored in the non-volatile storage means when the control data is an N-bit digital value. Instead, the actual voltage change width per unit resolution of the control data is calculated, and the ratio value to be multiplied by the digital value which is the control data at that time under actual operation of the load voltage control device is stored as the correction coefficient. A load voltage control method characterized by: 7. The load voltage control method according to claim 1, 2, or 3, wherein a voltage error to be allowed with respect to the design applied voltage value when the measured applied voltage is sent to the control circuit. If the measured applied voltage value is compared with the maximum value and deviates from the maximum value, or the measured applied voltage value exceeds the allowable upper limit value or falls below the allowable lower limit value, an alarm device is generated as a circuit failure of the control circuit. A warning is issued from the load voltage control method. 8. The method according to claim 1, 2, 3, 4, 5, 6 or 7.
The load voltage control method according to claim 1, wherein the control data is an N-bit digital value, and the control data corresponding to the design applied voltage value to be output by the control circuit at that time has the corresponding output digital value once. The output cycle is one output cycle, and the continuous m times are output as one control cycle, and the output digital in the output cycle from zero times to m-1 times of the m output cycles. By configuring so that the value can be selectively increased by +1 step,
Improving a substantial resolution by m times.