JPH05312845A - Control circuit of electric apparatus - Google Patents

Abstract

PURPOSE:To detect voltage of an electric power source easily at low cost by calculating voltage value from the inclination of voltage waveform of alternating current using a microcomputer having no specific function. CONSTITUTION:The inclination (k) of waveform is defined as k=(e1-e2)/(t1-t2) wherein t1 and t2 stand for the time when the voltage becomes e1 and e2, respectively, more or less 0V of waveform of a sine wave of electric power source voltage V. Since the inclination (k) is proportional to the voltage V, the voltage V can be known by knowing the inclination (k). The voltage e1, e2 to be detected are determined by input setting voltage of a comparator. When voltage V or its divided voltage is sent to the comparator and agrees with the input setting voltage, the output of a circuit is reversed. The voltage e1, e2 are detected by respective circuits, the obtained outputs are sent to a microcomputer as they are, computation is carried out to give the inclination (k), and thus electric power source voltage value V is calculated. Also, the outputs of the detection circuits are sent to the microcomputer as one pulse signal 3 using an EXCLUSIVE-OR element, computation is carried out, and thus the voltage value V is calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of household electric appliances, and more particularly to the control of the shaft output of electric motors, the output of which depends on the power supply voltage, and the heat generation control of electric heating appliances. It is related to the detection of the magnitude of the voltage for securing.

It also relates to the detection of the magnitude of the load current.

[0003]

2. Description of the Related Art In a conventional control circuit incorporating a microcomputer, the voltage of a commercial power supply is divided and reduced to the level of the DC voltage of the control circuit, and this voltage is converted into digital data by using an analog / digital conversion circuit. The magnitude of the voltage is detected by inputting it into a microcomputer or by using a microcomputer incorporating this analog / digital conversion circuit to perform detection and calculation.

Further, in detecting the magnitude of the load current, the maximum value of the output voltage of the current detection transformer is held, and this voltage is input to the microcomputer as digital data using an analog / digital conversion circuit, or , A microcomputer incorporating this analog / digital conversion circuit was used for detection, calculation, and detection of the magnitude of current.

[0005]

SUMMARY OF THE INVENTION Electric motors for rotating washing wings of electric washing machines, electric heaters for clothes dryers, etc. are greatly influenced by the output voltage of the electric power. For example, regarding an electric motor that rotates a washing wing, its shaft output changes in proportion to the square of the voltage value. Therefore, if the washing wing has the same rotational force and laundry, and if the load is the same, the washing water and the laundry are The speed of rotation of the device also changes according to the change of the power supply voltage.

That is, the strength of washing varies depending on the power source voltage. When the voltage is high, the washing is performed with a strong force, and when the power source voltage is lowered, the washing is weak.

Further, since the shaft output of the electric motor for rotating the washing wing changes according to the size of the load, if the shaft output can be known, the size of the load can be known. Since the shaft output of the electric motor is determined by the applied voltage and the flowing current, it can be calculated by detecting the applied voltage and the electric current of the electric motor that rotates the washing wing.

The conventional method of detecting a voltage using an analog / digital conversion circuit described in the preceding section requires a special circuit and a voltage capturing circuit, and the control circuit becomes complicated. And the cost becomes high.

An object of the present invention is to realize the detection of these power supply voltages by a simple and inexpensive circuit by using a microcomputer having no special function.

[0010]

In order to achieve the above object, the voltage taken in by a circuit for taking in a commercial power supply voltage waveform is devised for timing the load control of a motor or the like incorporated in a general control circuit. , Measure the time interval between two points. This makes it possible to detect the slope of the waveform of the power supply voltage, and to know the magnitude of the voltage without adding a special circuit.

[0011]

[Function] Since the voltage waveform of the commercial power supply is a sine wave, e = E sin
It is represented by (ωt), and the voltage gradient near the voltage 0V is related to its peak value E. If the peak value E is large, the voltage gradient is large, and if the peak value E is small, the voltage gradient is small, and The slope depends on the voltage peak value E. Therefore, in a commercial AC power supply having a sinusoidal voltage waveform, the voltage peak value E can be calculated by knowing the voltage gradient near the voltage 0V, and the effective voltage value V can be calculated from the voltage peak value E.

Since the output of the electric motor for rotating the washing wing of the electric washing machine, the electric heater of the clothes dryer, etc. is determined by the effective voltage value V, the control of the operating time of the electric motor for rotating the washing wing in the electric washing machine, By controlling the reversal interval, in the electric heater of the clothes dryer, by controlling the energization time to the electric heater and by controlling the energization interval, these electric devices are kept the same regardless of the fluctuation of the power supply voltage. You can drive with strength.

Since the output of the current detecting transformer depends on the voltage, the magnitude of the load current is detected in the same manner as reading the voltage gradient in the vicinity of the voltage 0V of the voltage waveform of the commercial power source. The output voltage can be calculated by reading the voltage gradient before and after the voltage of 0 V in the voltage waveform of the voltage, and the magnitude of the load current can be calculated if the output voltage is known.

[0014]

EXAMPLES Examples of the present invention will be described below.

In the electric washing machine, the rotation of the washing wing is operated at the number of rotations determined at the equilibrium point between the load amount related to the amount of laundry and the shaft output generated by the electric motor. If the motor determines the shaft output, it will be related to the product of the voltage of the power supply applied to it and the magnitude of the flowing current, and since the magnitude of the current changes in proportion to the voltage of the applied power supply, It can be said that the output changes in proportion to the square of the voltage value. Therefore, if the rotating force of the washing wing and the laundry are the same and the load is the same, the rotation speed of the washing water and the laundry also changes according to the change of the power supply voltage.

An ordinary electric washing machine which employs an induction motor as an electric motor is designed to be washed by repeatedly performing forward rotation and reverse rotation for a predetermined time. When the voltage is high and the shaft output of the electric motor is large, the rotation of the washing wing is high. Conversely, when the voltage is low and the shaft output of the electric motor is small, the rotation of the washing wing is low.

When the voltage is high, the shaft output of the electric motor is large, and the rotation of the washing wing is high, the operating time of the electric motor is shortened and the stop time is lengthened to weaken the washing strength, and the washing at the rated time is performed. Get strength. When the voltage is low, the shaft output of the electric motor is low, and the rotation of the washing wing is low, the operating time of the electric motor is lengthened and the stop time is shortened to increase the washing strength. obtain.

Further, in the method of detecting the amount of laundry by detecting the speed of deceleration of inertial rotation, the change in the magnitude of the power supply voltage causes a difference in the rotational force applied to the laundry and reduces the detection accuracy. However, the accuracy can be greatly improved by detecting the voltage and correcting the detected value by the method of the present invention.

In a control circuit of an electric washing machine which employs a microcomputer, the time when the power supply voltage becomes almost 0V is generally detected and signaled and input to the microcomputer in order to control the load control of the electric motor or the like.

As shown in FIG. 1, assuming that the time when the predetermined voltage e1 around 0 V of the sine wave waveform of the power supply voltage becomes t1 and the time when the other predetermined voltage e2 becomes t2, the waveform of the sine wave of the power supply voltage Can be defined by a value k such that k = (e1-e2) / (t1-t2), and this slope k is the voltage V
The voltage V of the power supply can be known by knowing the slope k.

When the slope k is obtained using the voltage waveform after full-wave rectification shown in FIG. 1 (b), the above equation is modified and defined as k = (e1-pe2) / (t1-t2). be able to. However, when p is set to detect a predetermined voltage e2 for detection by sandwiching e1 and 0V, p =
-1, and p = 1 otherwise.

A circuit for detecting the times t1 and t2 is shown in FIG. The voltages e1 and e2 to be detected are determined by the input set voltage of the comparator. When the power supply voltage or its divided voltage is input to the comparator and matches the input set voltage, the output of the circuit is inverted. A method of detecting the voltages e1 and e2 to be detected by the respective detection circuits, inputting the output signals thereof to the microcomputer as they are, calculating the slope k of the voltage waveform, and calculating the voltage value V of the power supply voltage.
Further, as shown in FIG. 2, the output of the detection circuit is converted into one pulse signal by using an exclusive OR circuit and is input to the microcomputer for calculation processing to calculate the slope k of the voltage waveform and the voltage value V of the power supply voltage. There is a way to do it.

When the slope k is obtained using the voltage waveform after full-wave rectification, the circuit configuration can be further simplified. The reduced voltage waveform of the power supply voltage is as shown in Fig. 1 (b), so the detection voltage e1 = e2 and the reference voltage can be set to one, and the comparator can be set to one. Is input as it is by using only one input port of the microcomputer, arithmetic processing is performed, the slope k of the voltage waveform is calculated, and the voltage value V of the power supply voltage is calculated.

FIG. 3 shows a method of obtaining the magnitude of the current of the commercial AC power source taken into the control circuit from the slope of the waveform of the output voltage of the load current detecting transformer. The output voltage of the current detection transformer changes in response to the magnitude of the load current,
The waveform has the same shape as the waveform of the AC voltage. Therefore, since the magnitude of the output voltage can be detected by the voltage detection method described above, the magnitude of the load current can be known.

Electric heaters such as clothes dryers and dishwashers change their heat output depending on the power supply voltage. Generally, the control of the heat output is turned on and off. In order to keep the heat generated by the electric heater constant regardless of voltage fluctuations, the ON / OFF control is performed so that the ON time is short and the OFF time is long when the voltage is high, and the ON time is long and the OFF time is long when the voltage is low. ON / OFF control is performed so as to shorten. High-accuracy temperature control can be performed by detecting the power supply voltage and performing timed control of on and off.

FIG. 4 shows a conventional detection method. In a conventional control circuit incorporating a microcomputer, the voltage of the commercial power supply is divided and reduced to the level of the DC voltage of the control circuit, and this voltage is used by an analog / digital conversion circuit.
It has been input as digital data into a microcomputer, or detected and calculated using a microcomputer incorporating this analog / digital conversion circuit to detect the magnitude of voltage.

[0027]

According to the present invention, the detection of the power supply voltage does not use an analog / digital conversion circuit or an expensive microcomputer with a built-in analog / digital conversion circuit, and does not have a general special function. Since it is possible to detect the power supply voltage inexpensively and easily by realizing it with a simple and inexpensive circuit using a computer, it becomes possible to perform fine control according to the voltage of the electric device,
There is an effect that it is possible to inexpensively provide an electric device that can widely cope with voltage fluctuations.

[Brief description of drawings]

FIG. 1 is a diagram showing a shape of a voltage waveform and a detection position.

FIG. 2 is a diagram showing one method of a voltage detection circuit.

FIG. 3 is a diagram showing a current detection transformer and a waveform of its output voltage.

FIG. 4 is a diagram showing a circuit method of voltage detection by a conventional method.

Claims (5)

[Claims] 1. In the control of an electric device which is operated by using a commercial AC power supply, the magnitude of the voltage of the commercial AC power supply taken into the control circuit is obtained from the slope of the voltage waveform and used to correct the control value. A control circuit for electric equipment characterized by: 2. The magnitude of the voltage of the commercial AC power supply according to claim 1, wherein the slope of the voltage waveform is calculated by measuring the time from the point equal to a certain predetermined voltage until it becomes equal to another predetermined voltage. A control circuit for an electric device, characterized in that it is used for determining a control value and correcting the control value. 3. In the control of an electric device that operates using a commercial AC power supply, the magnitude of the current of the commercial AC power supply taken into the control circuit via the load current detection transformer is used to detect the load current detection transformer. A control circuit for an electric device, which is used to correct a control value, which is obtained from a slope of a waveform of an output voltage of the device. 4. The magnitude of the load current is obtained by measuring the slope of the voltage waveform by measuring the time from the point equal to a certain predetermined voltage until it becomes equal to another predetermined voltage. A control circuit for electric equipment, which is used for correcting a control value. 5. The method according to claim 1, wherein the slope of the voltage waveform is determined by measuring the time from the point at which the pulsating current of the full-wave rectifier circuit is equal to a certain predetermined voltage until it becomes equal to another predetermined voltage. A control circuit for an electric device, which is calculated by performing the calculation, obtains the magnitude of the voltage of the commercial AC power supply, and uses it for correcting the control value.