Control device

Abstract

There is realized a control device capable of speeding up an output response without causing deterioration in the resolution of a time-proportional output. The control device controls a control object at a ratio of ON-time to OFF-time for a time-proportional output. The control device comprises a PID computation unit for executing PID computation of deviation between a set value and a measured value from the control object, an integrator for sequentially adding up control output values each representing the result of the PID computation executed by the PID computation unit, an ON/OFF determination unit for determining whether the time-proportional output is turned ON or OFF on the basis of an integrated value of the integrator, and a time-proportional output unit for turning the time-proportional output ON/OFF on the basis of a determination value of the ON/OFF determination unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing one embodiment of a control device according to the invention;

FIG. 2 is a flow chart showing an operation procedure for time-proportional output according to the invention;

FIG. 3 is a diagram for describing an output state of the time-proportional output according to the invention;

FIG. 4 is a view showing another embodiment of a control device according to the invention;

FIG. 5 is a block diagram showing the configuration of a conventional control device; and

FIG. 6 is a diagram for describing an operation of a conventional time-proportional driver.

Claims

1. A control device for controlling a control object at a ratio of ON-time to OFF-time for a time-proportional output, said control device comprising a PID computation unit for executing PID computation of deviation between a set value and a measured value from the control object, an integrator for sequentially adding up control output values each representing the result of the PID computation executed by the PID computation unit, an ON/OFF determination unit for determining whether the time-proportional output is turned ON or OFF on the basis of an integrated value of the integrator, and a time-proportional output unit for turning the time-proportional output ON/OFF on the basis of a determination value of the ON/OFF determination unit.

2. The control device according to claim 1, wherein the integrator integrates the control output value renewed for every control cycle by adding the latest control output value thereto for every resolution cycle.

3. The control device according to claim 2, wherein the resolution cycle corresponds to one half of a commercial power supply cycle delivered to the control object.

4. The control device according to claim 1, wherein the ON/OFF determination unit determines the reciprocal of the resolution of the time-proportional output as a maximum value of a control output.

5. The control device according to claim 4, wherein the ON/OFF determination unit determines that the time-proportional output is ON if the integrated value exceeds the maximum value of the control output value.

6. The control device according to claim 4, wherein the ON/OFF determination unit subtracts the maximum value from the integrated value upon the integrated value exceeding the maximum value, thereby sending back the difference to the integrator.

7. The control device according to claim 2, wherein the time-proportional output unit turns the time-proportional output ON for one period of the resolution cycle if the ON/OFF determination unit makes an ON-determination.