JPH01287717A - Load controller - Google Patents

Abstract

PURPOSE:To perform control with high accuracy and the detection of a fault by outputting an abnormality generation signal without detecting the change of the output value of an A/D converter by a control means when the fault (in which a constant output value is issued in spite of the level of an input/ output voltage) is generated in the A/D converter. CONSTITUTION:The control means 11 inputs the output values from the A/D converters 8 and 9, and outputs a control signal to a transistor 4 that is a load in case of detecting the change of the output value at the time of changing the input voltage of the A/D converters 8 and 9 by an input voltage change means 15 consisting of transistors 13 and 14, and outputs to abnormality generation signal to a transistor 12. However, in case of detecting no change of the output value of the A/D converters 8 and 9 at the time of changing the input voltage of the A/D converters 8 and 9 by a the input voltage change means 15, the control means 11 outputs the abnormality generation signal, and stops the energizing of a heater 2 compulsorily by turning ON the transistor 12. In such a way, it is possible to perform the control with high accuracy and the detection of the fault.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load control device that detects a value using a sensor and controls a load based on the detected value.

2. Description of the Related Art A temperature control device is shown in FIG. 4 as an example of a conventional load control device of this type. 1 is the power supply, 2 is the heater.

3 is driven by transistor 4 and turns heater 2 ON/OFF
It is a relay that 5 is a resistor, 6 is a thermistor for detecting the temperature of the heater 2, and 7 is a volume for setting the heater 2 to a desired temperature. Reference numerals 8 and 9 denote A/D converters, into which the temperature signal voltage from the thermistor 6 and the setting signal voltage from the volume 7 are respectively input. 10 is a control means for driving a transistor 4 which is a load, and an A/I) converter 8
．． 9 signals are input. A/D converters 8, 9 and relay control means 10 constitute an input voltage detection device.

The control means 10 performs so-called three-value control in which it detects that the output values of the A/D converters 8 and 9 are within a certain range and stops the driving means 4 if they are outside the certain range.

Problems to be Solved by the Invention However, the above configuration has the following problems.

(1) The method of detecting the A/D converter output value outside a certain range as shown in the conventional example reduces the dynamic range of the input voltage of the A/D converter, making it susceptible to noise etc. The resolution of the input voltage signal (temperature in the conventional example) before voltage conversion is reduced, and only less accurate control can be performed.

(2) With conventional methods that only enable output values within a certain range, when an A/D converter fails, the output value remains constant regardless of the input voltage. Failures of this type cannot be detected, and as a result, there is a risk of smoke, fire, etc. in some types of loads, such as temperature control devices.

The present invention provides a load control device that solves the problems listed in item L, can perform highly accurate control, and can detect failures.

Describing Means for Solving the Problems In order to solve the problems, the load control device of the present invention has the following features:
An A/D converter, an input voltage changing means for forcibly changing the input voltage to the A/D converter, and an output value change of the A/D converter when the input voltage is changed by the input voltage changing means. and control means for controlling the load according to the output value of the A/D converter when a change is detected, and outputting an abnormality occurrence signal when no change is detected.

Due to the working soil structure, the control means will be able to control A/D in the event of a failure of the A/D converter (a failure in which the output value remains constant regardless of the input voltage).
/D converter output value change is not detected and an abnormality occurrence signal is output.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

FIG. 1 is a block diagram of a temperature control device using an input voltage detection device showing one embodiment of the present invention.

The same signals are given to the same components as in the conventional example, and detailed explanation thereof will be omitted. 11 is a control means that inputs the output values from the A/D converters 8 and 9, and transistors 13 and 14.
The input voltage changing means 15 configured with the input voltage changing means 15 detects the change in the output value when the input voltage of the A/D converters 8 and 9 is changed, and when a change is detected, controls the transistor 4, which is the load, to turn ON or OFF. A signal is output, but an abnormality occurrence signal is not output to the transistor 12. However, the A/D converters 8 and 9 by the input voltage changing means 15
If a change in the output values of the A/D converters 8 and 9 cannot be detected when the input voltage is changed, the control means 11 outputs an abnormality signal and turns on the transistor 12 to stop the heater 2 from being energized. force to stop.

FIG. 2 is a flowchart of the load control device of the same embodiment. First, the A/D conversion value of the A/D converter 8 or 9 is inputted by the upper 1 control means 11.

Next, the input voltage of the A/D converter 8 or 9 is changed by the input voltage changing means, and then the current A/D conversion value P2 is inputted by the control means 11. The control means 11 compares the A/D conversion value 1 and the A/D conversion value P2, and if there is a change, increases the A/D conversion value by 1 to control the load 4, and returns to the start again to repeat this process. Further, if there is no change in the A/D conversion value or the 1/D conversion value P2, the control means 11 outputs an abnormality occurrence signal.

In addition, if there are multiple A/D converters as in this example, and they are configured on one chip, the input voltage corresponding to that A/D converter may be changed to the output value due to an internal failure of the chip. In some cases, an input voltage corresponding to another A/D converter may be converted into an output value without converting it into an output value. For example, as shown in Figure 3,
When the A/D converter 8.9 is composed of one chip, the A/D converter 8 and the A/D converter 9 Failure to convert the input voltage may occur.

Even in such a case, failure detection can be performed by using the configuration of the present invention. Moreover, the control means 11 and A
The same is true for a microcomputer with a built-in A/D converter in which the A/D converters 8 and 9 are constructed on one chip.

Effects of the Invention As described above, the load control device of the present invention provides the following effects.

(1) The output value of the A/D converter is used as effective only within a certain range for load control. Since it is not a so-called three-value control, the entire input range of the A/D converter can be used.
The resolution ability is improved, and highly accurate control can be performed, and it can also be made resistant to noise.

(2) It is possible to detect a failure that shows a constant output value regardless of the input voltage of the A/D converter.

(3) When using multiple A/D converters in one chip, the output value is output based on the input voltage of other A/D converters, not depending on the input voltage corresponding to one A/D converter. It becomes possible to detect failures.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a load control device according to an embodiment of the present invention;
FIG. 2 is a flowchart of the same embodiment, and FIG. 3 is a flowchart of the same embodiment.
FIG. 4 is a block diagram showing an example of a conventional load control device. 8.9... A/D converter, 11... Control means, 15... Input voltage changing means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] An analog-to-digital converter (hereinafter referred to as an A/D converter), an input voltage changing means for forcibly changing the input voltage to the A/D converter, and an input voltage changing means for forcibly changing the input voltage to the A/D converter; A load control device comprising a control means that controls a load according to the output value of the A/D converter when a change in the output value of the A/D converter is detected, and outputs an abnormality occurrence signal when the change in the output value is not detected.