JPH02294236A - Microcomputer electric water heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a microcomputer electric water heater.

[Prior Art] As shown in FIG. 5, a conventional microcomputer electric water heater 51 includes a tank 52 for storing and keeping water warm, a heater 53 for heating water in a tank 5z, and a heater 53 for heating water in a tank 5z. A temperature sensor 54 that detects the temperature, a heating temperature selection switch 55 that selects the heating temperature, and a 100V AC power supply 56
The power supply circuit 57 converts AC power into DC power, a reset circuit 58, a microcomputer 59, and a heater output circuit 60.

The AC power from the 200v AC power supply 61 is supplied to the timer 62.
For example, electricity is supplied at the night rate during the hours of PMII: 00 to 7:00 AM. The AC power from this AC power source 61 is supplied to the heater 5 via an earth leakage breaker 63, a relay switch 65 of a relay 64, and an overtemperature preventer 66.
3. The relay switch 65 is turned on and off by commands from the microcomputer 59 to the heater output circuit 60 that excites the relay coil 67 of the relay 64.
Be cut off. When the relay switch 65 becomes conductive, the heater 53 is energized by AC power from the AC power source 61, and the water in the tank 52 is heated. The temperature of the water in the tank 52 is detected by the temperature sensor 54 and notified to the microcomputer 59. The boiling temperature of the water in the tank 52 is set by the user operating the temperature selection switch 55. This setting content is the microcomputer 59
be taken in. The microcomputer 59 looks at the temperature detected by the temperature sensor 54 and the boiling target temperature set by the boiling temperature selection switch 55, and controls the relay switch 65 to turn on and off to control the heating of the heater 53. Let's do it.

With such a configuration, water in the tank can be boiled at low nighttime electricity rates.

[Problem to be solved by the invention] The 200cm power supply for energizing the heater is inexpensive to use, but it is difficult to use it within a predetermined time period (PMII: OO~
AMP:00), power supply is stopped. Therefore, the conventional microcomputer electric water heater requires an IOOV for supplying power to the microcomputer in addition to the 200V power supply, making the wiring complicated.

Moreover, since two wiring works were required, one from the 200V AC power supply and the other from the IOOV AC power supply, the construction cost increased.

Furthermore, it is necessary to use an expensive 100V AC power supply.

The purpose of the present invention is to solve the above-mentioned technical problems, and to provide a microcomputer electric water heater that does not use a TOOV power supply, simplifies wiring, reduces construction costs, and has improved reliability. do.

[Means for Solving the Problem] The microcomputer electric water heater according to claim (1) includes a heater that heats water in a tank and is energized by AC power such as a 200V AC power supply that is supplied for a predetermined time. , a temperature sensor that detects the temperature of water in the tank, a boiling temperature selection switch that selects the boiling temperature, and a boiling target temperature that is set by the temperature detected by the temperature sensor and the boiling temperature selection switch. and a microcomputer that controls the heating of the heater,
a power supply circuit that converts the 200cm AC power supplied from the AC power supply to a predetermined DC voltage; and a backup power supply circuit that charges the microcomputer during the predetermined time and supplies power to the microcomputer outside the predetermined time. This includes:

The microcomputer electric water heater according to claim (2) further uses an electric double layer capacitor for the backup power source.

The microcomputer electric water heater according to claim (3) further uses a microcomputer having a standby function that reduces power consumption while retaining stored contents during times other than the predetermined time.

The microcomputer electric water heater according to claim (4) further detects whether or not 200V AC power is being supplied from the AC power supply, and when the power supply is stopped, the microcomputer enters a standby mode and the power is supplied. This includes a power failure detection circuit for canceling the microcomputer from standby mode when the microcomputer starts.

In the microcomputer electric water heater according to claim (5), when the supply of 200V AC power from the AC power source is stopped, the microcomputer determines whether it is a normal power supply stop or a power outage; After the supply of 200V AC power from the AC power source is started, the peak shift is skipped and power energization of the heater is started.

The microcomputer electric water heater according to claim (6) further includes a reset switch for clearing the memory contents of the microcomputer, and a reset switch for clearing the memory contents of the microcomputer when 200V AC power is supplied from the AC power supply. a reset stop circuit that allows the memory contents to be cleared according to the operation, and prevents the memory contents from being cleared regardless of whether the reset switch is operated when the supply of 200V AC power from the AC power source is stopped; This includes:

The microcomputer electric water heater according to claim (7) monitors the output voltage of the backup power supply circuit, and when the output voltage falls below a predetermined voltage at which it is no longer possible to retain the memory contents of the microcomputer, the microcomputer electric water heater disconnects the power from the AC power supply. The microcomputer includes a voltage monitoring circuit that clears the memory contents of the microcomputer when the 200V AC power supply starts.

[Function] In the microcomputer electric water heater according to claim (1), the power supply circuit includes:
The 200V AC power supplied from the AC power source is converted to a predetermined DC voltage.

The backup power supply charges during the specified time and
Power is supplied to the microcomputer at times outside the predetermined time.

Shitaka allows you to configure a microcomputer electric water heater without using a 100V power supply. Furthermore, since a 100V power supply is not used, wiring can be simplified and construction costs can be reduced.

In the microcomputer electric water heater according to claim (2), an electric double layer capacitor is further used as a backup power source.

Therefore, maintenance can be eliminated.

In the microcomputer electric water heater according to the third aspect of the present invention, a microcomputer is further used that has a standby function that reduces power consumption while retaining stored contents during times other than the predetermined time.

Therefore, the output voltage of the backup power supply can be maintained high for a long time. Furthermore, the charging capacity (2) of the backup power source can be reduced.

In the microcomputer electric water heater according to claim (4), the power failure detection circuit further detects whether or not 200V AC power is being supplied from the AC power supply, and when the power supply is stopped, the microcomputer is placed in standby mode. When power supply starts, the microcomputer is released from standby mode.

Therefore, the output voltage of the backup power supply can be maintained high for a long time. Furthermore, the charging capacity of the backup power source can be reduced.

In the microcomputer electric water heater of claim (5), the microcomputer further determines whether the normal power supply is stopped or a power outage occurs when the supply of 200V AC power from the AC power source is stopped. In some cases, after the supply of 200V AC power from the AC power supply is started, the peak shift is skipped and power energization of the heater is started.

Therefore, it is possible to eliminate the inconvenience that the power supply time ends before the boiling temperature reaches the set temperature.

In the microcomputer electric water heater according to claim (6), the reset switch is further provided for clearing the memory contents of the microcomputer.

The reset stop circuit allows the memory contents to be cleared according to the operation of the reset switch when 200V AC power is supplied from the AC power supply, and when the 200V AC power is supplied from the AC power supply,
When the supply of 00V AC power is stopped, clearing of the memory contents is prevented regardless of the operation of the reset switch.

Therefore, the microcomputer does not start up when power is not supplied from the AC power source, and runaway of the microcomputer can be prevented.

In the microcomputer electric water heater according to claim (7), the power supply voltage monitoring circuit monitors the output voltage of the backup power supply circuit, and when the output voltage falls below a predetermined voltage at which it is no longer possible to retain the memory contents of the microcomputer, the power supply voltage monitoring circuit monitors the output voltage of the backup power supply circuit. , when the supply of 200V AC power from the AC power source is started, the memory contents of the microcomputer are cleared.

Therefore, the microcomputer will not start up due to incorrect storage contents, and the microcomputer will be prevented from running out of control.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention.

The microcomputer electric water heater 1 has a tank 2 that stores and keeps water warm.
, a heater 3 that heats the water in the tank 2, a temperature sensor 4 that detects the temperature of the water in the tank 2, a boiling temperature selection switch 5 that selects the boiling temperature, a power supply circuit 6, and a backup power supply. 7, a power supply voltage monitoring IC 8 as a power supply voltage monitoring circuit, a reset circuit 9, a reset stop circuit 1o, a power failure detection circuit 11, a microcomputer 12, and a heater output circuit 13.

The AC power from the 200V AC power supply 14 is supplied to the timer l5.
For example, power is supplied at the night rate during the time period from PMII: 00 to 7:00 AM. AC power from this AC power supply 14 is supplied to the heater 3 via the earth leakage breaker 16, the relay switch 18 of the relay 17, and the overtemperature rise preventer l9. The relay switch l8 is turned on and off by commands from the microcomputer l2 to the heater output circuit l3 that excites the relay coil 20 of the relay l7. When the relay switch l8 is turned on, the heater 3 is energized by the AC power from the AC power source 14, and the water in the tank 2 is heated. The temperature of the water in the tank 2 is detected by the temperature sensor 4 and is notified to the microcomputer 12. The boiling temperature of the water in the tank 2 is set by the user operating the temperature selection switch 5. This setting content is imported into the microcomputer 12.

The microcomputer 12 consists of one chip, and includes a CPU ROM SRAM and the like inside. The microcomputer 12 also has a drain power supply voltage terminal V DIl+% to which a DC voltage is applied, a source power supply voltage terminal V H which is grounded, and a reset terminal RE to which a reset signal is manually input.
SET, power failure detection port and start terminal START
Equipped with etc. The ROM calculates how many hours it will take from the boiling time to reach the target temperature by looking at the temperature detected by the temperature sensor 4 and the boiling target temperature from the boiling temperature selection switch 5, and then starting the heater. A predetermined program such as a program for determining the time to start energizing the power of No. 3 and making the relay switch l8 conductive at that time is stored. R.A.
M contains the time to start energizing the heater 3 and a special character written in the specific number value, such as rsEK.
IsUIJ, the cumulative power supply time of the AC power source 14, a flag, a checksum written to the final address, etc. are stored.

The power supply circuit 6 includes a power transformer 21 that steps down 200V to 9V, a bridge diode 22 and a capacitor 23 that rectifies and smoothes the stepped down AC power, a capacitor 24 that removes high frequency noise, and a constant voltage that stabilizes the voltage. It includes an IC 25 and a diode 26. Constant voltage IC
The voltage output from 25 is, for example, 5V. Since AC power is supplied from the AC power supply 14 during the time period of PMII: 00 to 7:00 AM, the constant voltage IC 25 supplies P
A constant voltage of 5 cm is output during the time period from MII:00 to AM7:00.

The backup power supply circuit 7 includes a diode 27 and a resistor 2.
8 and an electric double layer capacitor 29.

From constant voltage IC25, PMII: 00 to AM 7:00
Since a constant voltage of 5V is output during this time period, the electric double layer capacitor 29 is charged with DC power from the constant voltage IC 25 of the power supply circuit 6 via the diode 27 and the resistor 28 during this time period. Diode 27 prevents backflow. Note that the electric double layer capacitor 29 has a large capacity, for example, several F. The output of the backup power supply 7 is supplied with DC power from the constant voltage IC 25 of the power supply circuit 6 via the diode 27 or the resistor 2.
Direct current power from the electric double layer capacitor 29 appears via 8. After high frequency noise is removed by the capacitor 30, this DC power is transferred to the microcomputer l2.
1. Rain power supply voltage terminal VDD and power supply voltage monitoring I
It is applied to the sense input SEXSE of C8.

The power supply voltage monitoring IC 8 outputs a low level signal from its output terminal when the voltage applied to the sense input SENSE becomes less than a predetermined voltage. Further, if the voltage is higher than a predetermined voltage, a high level signal is output. This predetermined voltage is
This is a voltage that guarantees the storage contents of the RAM and CPU register in the standby mode of the microcomputer 12, and is 2V in this embodiment. The output from the output terminal of the power supply voltage monitoring IC 8 is applied to the reset terminal RESET of the microcomputer 12 after noise is removed by a resistor 31 and a capacitor 32 .

The reset circuit 9 includes a reset switch 33 and a low resistance 34.
Equipped with. This reset switch 33 and resistor 34
is connected in series between the output of the constant voltage IC 25 of the power supply circuit 6 and the ground. The output of constant voltage IC25 is PM11
:00 to 7:00 AM, the voltage is 5V. Gatte, PMI l:00-AM7:
When the operator suppresses the reset switch 33 during the 00(7) time period, the reset switch 33 becomes conductive and the common connection point C between the reset switch 33 and the resistor 34
OM becomes high level. When the reset switch 33 is cut off, the common connection point COM becomes low level. During times other than PMII:00-7:00 AM, the output of the constant voltage IC 25 is rOJV, so even if the reset switch is pressed, the common connection point COM is at a low level.

On the other hand, the output of the power supply voltage monitoring IC8 is PMII:00~
AM7. In the time zone of 00, it is at a high level.

Also, PMII: 00-AM? - In time zones other than 00, the output of the power supply voltage monitoring IC 8 is at a high level or a low level depending on the discharge state of the electric double layer capacitor 29.

When the reset switch 33 is pressed and released, the PMI
During the time period from I:00 to 7:00 AM, the transistor 37 is turned on and off, and the reset terminal RESET of the microcomputer 12 changes from a high level to a low level, and then from a low level to a high level.

In a time zone other than PMII: 00 to AMT: 00, even if the reset switch 33 is suppressed or released when the output of the power supply voltage monitoring IC 8 is at a high level, the output of the constant voltage IC 25 is at a low level. Transistor 37 never becomes conductive. Therefore, the reset terminal RESET of the microcomputer l2 is kept at high level by the output of the power supply voltage monitoring IC8.

In a time zone other than PMII: 00 to AM7: 00, when the output of the voltage monitoring IC 8 is at a low level, even if the reset switch 33 is suppressed or released, the output of the constant voltage IC 25 is at a low level. , transistor 37 never becomes conductive. Therefore, the reset terminal RESET of the microcomputer l2 is kept at a low level by the output of the power supply voltage monitoring IC8.

The reset stop circuit 10 includes a resistor 35. 36 and a transistor 37. Resistor 35 is connected between the common connection point of reset switch 33 and resistor 34 and the base of transistor 37. The emitter of transistor 37 is grounded. The collector of the transistor 37 is connected to the output of the constant voltage IC8. Resistor 36 is connected between the output of backup power supply 7 and the output of power supply voltage monitoring IC 8 .

The power failure detection circuit 11 includes resistors 38, 39. 40, diode 4l, photocoupler 42, and capacitor 43
Equipped with. Resistor 38 and diode 41 are connected in parallel to the secondary winding of power transformer 21 of power supply circuit 6 . A light emitting diode 44 of the photocoupler 42 is connected in parallel to the diode 41 in a reverse direction. Photo coupler 42
The collector of the phototransistor 45 is connected to the output of the power supply circuit 6. The emitter of phototransistor 45 is grounded via resistor 39.

A series circuit including a resistor 40 and a capacitor 43 is connected in parallel to the resistor 39. A common connection point of the resistor 40 and the capacitor 43 is connected to a power failure detection port and a start terminal START of the microcomputer 12.

PMII.OO to AM7: During the Go time period, AC power is supplied from the AC power supply 14, so the secondary winding of the power transformer 21 outputs a 9V AC signal. The diode 41 is conductive during a half period of this AC signal, and the light emitting diode 4 is conductive during the other half period.
4 conducts and emits light. Due to the light emission from the light emitting diode 44, a photocurrent flows through the phototransistor 45.

Therefore, one pulse signal with a duty ratio of 50% is output from the emitter of the phototransistor 45 in one cycle of the AC signal.

After noise is removed from this pulse signal by a resistor 40 and a capacitor 43, the microcomputer 12
is applied to the power failure detection port and start terminal START.

Since AC power is not supplied from AC power supply l4 during times other than PMII: 00 to AMP: 00,
The light emitting diode 44 does not emit light. Also, constant voltage IC
The output of 25 is "0" ■. Therefore, no pulse signal is output from the emitter of the phototransistor 45.

Drain power supply voltage terminal VD of microcomputer 12
D is connected to the common connection point of diode 27 and resistor 28. Therefore, PMII:00~AMP:00
During the time period, the DC power from the constant voltage IC 25 of the power supply circuit 6 is supplied to the drain power supply voltage terminal (2) of the microcomputer 12 via the diode 27. . given to. In addition, in times other than PMII: 00 to 7:00 AM, the electric double layer capacitor 29 via the resistor 28
DC power is applied to the drain power supply voltage terminal VDI of the microcomputer 12.

Microcomputer l2 has a reset terminal RESET
The contents of the RAM and CPtJ registers are initialized in response to the rise of the signal input from low level to high level.

The microcomputer 12 has a standby function that reduces power consumption. The power consumption of the microcomputer l2 at this time is, for example, 0.1% of the normal power consumption.
become. A predetermined time, e.g. 50ms, is applied to the power failure detection port.
If there is no ec time pulse signal, the power outage processing program will start, and after predetermined processing, will stop executing the CPU program, enter standby mode, and save RAM and CPU.
Holds the contents of the PU register.

The standby mode is canceled by setting the start terminal START to a high level, and the mode returns to the normal mode.

Also, by changing the reset terminal RESET from low level to high level, the standby mode is canceled and the normal mode returns. When returning to the normal mode, the CPU resumes execution from the program at the point of stop after predetermined processing.

Note that in the standby mode, if the voltage supplied to the drain power supply voltage terminal vDD is 2.0 V or more, the contents stored in the RAM and the registers of CPtJ are guaranteed. If it becomes less than 2.0V, the stored contents are not guaranteed. Additionally, when returning from standby mode to normal mode, if the voltage supplied to the drain power supply voltage terminal V0 is 4.5V or higher, the CPU is guaranteed to resume program execution without running out of control. be done.

If ■I)D is less than 4.5V when returning to normal mode, there is a risk that the CPU will run out of control.

In the normal mode, the microcomputer 12 counts the number of pulses of the pulse signal input to the power failure detection port and integrates the energization time of the 200V AC power supply.

This integration result is stored in an integration timer provided in the RAM.

When the power supply from the AC power supply 14 is stopped, the microcomputer 12 determines whether the power supply from the AC power supply 14 is a normal power supply stop or a power supply stop due to a power outage.

This determination is made as shown in FIG.

In step m1, AC 200V is converted into a pulse signal. This is done by the power failure detection circuit 1l. Next, in step m2, a fixed time of 50 msec
Determine whether there is a falling edge of the signal within this range. If the signal falls within a certain period of 50 msec, the process proceeds to step m3, and it is determined that 200V current is being applied. If the signal does not fall within a certain period of time of 50 msee, the process proceeds to step m4, and it is determined that there is no 200V energization.

That is, a stop in the power supply of the AC power source l4 is detected. Next, the process proceeds to step 5, where it is determined whether the cumulative energization time is longer than a predetermined time. If the accumulated time is equal to or longer than the predetermined time, it is determined that there is no power outage and that normal energization has been stopped, and the process proceeds to step m6, where after normal processing, the standby mode is entered. The normal processing includes a process of resetting the integrated value, a process of setting a flag indicating that there is a beak lift, a process of cutting off the relay switch l8, and the like. If the cumulative time is less than the predetermined time, it is determined that a power outage has occurred, and the process proceeds to step m7, where after processing the power outage, the standby mode is entered. For power outage processing,
There are processes such as setting a flag indicating that there is no peak shift, and cutting off the relay switch 18.

Here, the peak shift is a method adopted to prevent power usage from being concentrated at PMII:00 and to save power, and is as follows. PM11:
If the heater 3 is energized from the start of power supply to the DO, there is a risk that the power demand will exceed the supply capacity. Also, PMII・
When heater 3 is energized from the start of power supply at 00, AM
In many cases, the target boiling temperature is reached by the end of power supply at 7:00. In such a case, it is necessary to maintain the boiling temperature by controlling the heater 3 ON/OFF even after reaching the boiling temperature κ1, which results in wasted power consumption.

Therefore, we started supplying 200V power to the heater 3 (PM
ll:00) and not immediately at the same time, but at the end of power supply (
The power to the heater 3 is energized at different times so as to reach the boiling temperature exactly at AM7:'00). In this way, the consumption of 200V power can be reduced to P
No need to concentrate on MII:00 and no waste in power consumption. This is called peak shift.

However, in the past, it was not determined whether the AC power supply 14 was stopped supplying power or there was a power outage.
Even if there is a power outage after the AC power source 14 starts energizing, as shown in FIG.
It was mistakenly determined that the power supply started at II:00, and a peak shift occurred again.

Therefore, there arises an inconvenience that the energization time ends before the nl+ raising temperature reaches the set temperature.

However, in the present invention, if there is a power outage after the AC power source l4 starts energizing, a process is performed to set a flag indicating that there is no peak shift. Therefore, after the power is restored, as shown in FIG. 4, the heater 3 is energized without peak shift. Therefore, it is possible to eliminate the inconvenience that the energization time ends before the boiling temperature reaches the set temperature due to the peak shift being applied again.

Further, a special character, for example, rSEKIsUIJ, is written in a specific number value of the RAM of the microcomputer 12, and a checksum is written in the final address of the RAM. At the end of normal operation, this character and checksum are checked. Therefore, garbled data etc. are prevented and reliability is improved.

In the microcomputer electric water heater 1 configured in this way,
When AC power is being supplied from the AC power supply l4, that is, during the time period from PMII: 00 to 7:00 AM, and when there is no power outage, a constant voltage of 5■ is output from the power supply circuit 6. Ru. Microcomputer l2 is therefore powered through diode 27.

In addition, the electric double layer capacitor 29 of the backup power supply 7
is to charge. Further, the power supply voltage monitoring IC 8 outputs a high level signal to the reset terminal RESET of the microcomputer 12. Further, the power failure detection circuit l1 outputs a pulse signal to the power failure detection port and start terminal START of the microcomputer l2. As a result, the microcomputer 12 can control the relay switch 18 to turn on and off, thereby boiling the water in the tank 2 to the target temperature.

When AC power is not being supplied from the AC power supply 14, that is, PMII: 00-AM? - When the time is other than 00, or when a power outage occurs, the electric double layer capacitor 29 outputs the charged electric charge. Therefore, microcomputer l2 is powered through resistor 28. As a result, 100
No 100V AC power supply is required, and 100V wiring can be eliminated. Furthermore, the diode 27 prevents backflow. Therefore, the charges charged in the electric double layer capacitor 29 will not flow backward and be wasted. Also,
In the present invention, an electric double layer capacitor 29 is used.

Therefore, unlike NiCd batteries, there is no need to limit the number of charging/discharging cycles or worry about the lifespan, and there is no need for maintenance. Moreover, since it uses a large capacity,
Sufficient electric charge can be charged, and the electric double layer capacitor 29 is charged with electric charge to provide power backup. Furthermore, the power of microcomputer l2 is backed up, it enters standby mode, and the RAM
and stores the contents of the CPU's registers. Therefore, it is possible to perform processing with or without peak shift.

On the other hand, since the output of the power supply circuit 6 is rOJ, the power failure detection circuit 11 does not output a pulse signal to the power failure detection port and the start terminal START of the microcomputer 12. Therefore, the microcomputer l2 is in standby mode and consumes less power. This makes it possible to reduce the consumption of the electric charge stored in the electric double layer capacitor 29.

Further, even if the reset switch 33 is pressed, the output of the power supply circuit 6 is rOJ, so the reset stop circuit 10
The transistor 37 is not conductive, and the reset switch RESET of the microcomputer 12 never changes from low level to high level. Therefore, the microcomputer 12 does not start up, and the microcomputer 12 can be prevented from running out of control.

Furthermore, the power supply voltage monitoring IC 8 detects that the output of the backup power supply 7 has decreased and 2. If it becomes OV, the low level signal is sent to the reset terminal RESE of the microcomputer 12.
When power supply starts from the AC power source 14, a high level signal is output. Therefore, the microcomputer 12 will not start up due to the incorrect memory contents of the RAMSCPU register.
2 can be prevented from running out of control.

If AC power is no longer supplied from AC power supply l4,
That is, when the time of AM7:DO arrives, or
In the event of a power outage, it is determined whether the normal power supply ends or a power outage occurs, and in the case of a power outage, a peak shift is not applied when power supply starts. Therefore, it is possible to eliminate the inconvenience that the energization time ends before the boiling temperature reaches the set temperature.

[Effect of the invention] In the microcomputer electric water heater of claim (1), the power supply circuit includes:
The 200V AC power supplied from the AC power source is converted to a predetermined DC voltage.

The backup power supply charges during the specified time and
Power is supplied to the microcomputer at times outside the predetermined time.

Therefore, a microcomputer electric water heater can be constructed without using a 100■ power supply. Furthermore, since no lOOV power supply is used, wiring can be simplified and construction costs can be reduced.

In the microcomputer electric water heater according to claim (2), an electric double layer capacitor is further used as a backup power source.

Therefore, maintenance can be eliminated.

In the microcomputer electric water heater according to the third aspect of the present invention, a microcomputer is further used that has a standby function that reduces power consumption while retaining stored contents during times other than the predetermined time.

Therefore, the output voltage of the backup power supply can be maintained high for a long time. Furthermore, the charging capacity of the backup power source can be reduced.

In the microcomputer electric water heater according to claim (4), the power failure detection circuit further detects whether or not 200V AC power is being supplied from the AC power supply, and when the power supply is stopped, the microcomputer is placed in standby mode. When the microcomputer is turned on and power supply starts, the microcomputer is released from standby mode.

Therefore, the output voltage of the backup power supply can be maintained high for a long time. Furthermore, the charging capacity of the battery pack power source can be reduced.

In the microcomputer electric water heater of claim (5), the microcomputer further determines whether the supply of 200μ AC power from the AC power supply is stopped, whether it is a normal power supply stop or a power outage. In the case of a power outage, after the supply of 200V AC power from the AC power supply is started, the peak shift is skipped and power energization of the heater is started.

Therefore, it is possible to eliminate the inconvenience that the power supply time ends before the boiling temperature reaches the set temperature.

In the microcomputer electric water heater according to claim (6), the reset switch is further provided for clearing the contents stored in the microcomputer.

The reset stop circuit allows the memory contents to be cleared according to the operation of the reset switch when 200V AC power is supplied from the AC power supply, and when the 200V AC power is supplied from the AC power supply,
When the supply of 00V AC power is stopped, clearing of the memory contents is prevented regardless of the operation of the reset switch.

Therefore, the microcomputer does not start up even when power is not supplied from the AC power supply, and runaway of the microcomputer can be prevented.

In the microcomputer electric water heater according to claim (7), the power supply voltage monitoring circuit monitors the output voltage of the backup power supply circuit, and when the output voltage falls below a predetermined voltage at which it is no longer possible to retain the memory contents of the microcomputer, the power supply voltage monitoring circuit monitors the output voltage of the backup power supply circuit. , when the supply of 200V AC power from the AC power source is started, the memory contents of the microcomputer are cleared.

Therefore, the microcomputer will not start up due to incorrect storage contents, and the microcomputer will be prevented from running out of control.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of an embodiment of the present invention, Figure 2 is a 200v
A flowchart for explaining whether or not the power supply is being supplied and determining whether the power supply is stopped or a power outage. FIG.
FIG. 4 is a diagram for explaining the operation of the present invention in which no peak shift occurs after power is restored, and FIG. 5 is a circuit diagram of a conventional microcomputer electric water heater. 1... Microcomputer electric water heater 2... Tank 3... Heater 4... Temperature sensor 5...? Jli raising temperature selection switch 6...power supply circuit 7...backup power supply 8...power supply voltage monitoring IC 9...reset circuit lO...reset stop circuit 11...power failure detection circuit 12... Microcomputer 13...Heater output circuit 14...AC power supply 29...Electric double layer capacitor Patent applicant Sekisui Chemical Co., Ltd. Representative Kaoru Hirota Diagram diagram

Claims (7)

[Claims] (1) A heater that is powered by AC power from a 200V AC power supply that is supplied for a predetermined period of time to heat the water in the tank, a temperature sensor that detects the temperature of the water in the tank, and a temperature sensor that detects the temperature of the water in the tank. In a microcomputer electric water heater comprising a boiling temperature selection switch to select, and a microcomputer controlling the heating of the heater by checking the temperature detected by a temperature sensor and the boiling target temperature set by the boiling temperature selection switch. , a power supply circuit that converts the 200V AC power supplied from the AC power supply to a predetermined DC voltage; and a backup power supply circuit that charges the microcomputer during the predetermined time and supplies power to the microcomputer outside the predetermined time. A microcomputer electric water heater comprising: (2) The microcomputer electric water heater according to claim (1), wherein an electric double layer capacitor is used for the backup power source. (3) Claim (1) characterized in that a microcomputer is used that has a standby function that reduces power consumption while retaining memory contents during times other than the predetermined time.
) or (2) microcomputer electric water heater. (4) Detects the presence or absence of 200V AC power supply from the AC power supply, puts the microcomputer into standby mode when the power supply stops, and puts the microcomputer into standby mode when the power supply starts. The microcomputer electric water heater according to claim 3, further comprising a power failure detection circuit for canceling the standby mode. (5) When the supply of 200V AC power from the AC power supply is stopped, the microcomputer determines whether it is a normal power supply stop or a power outage, and if it is a power outage, the supply of 200V AC power from the AC power supply is stopped. 4. The microcomputer electric water heater according to claim 1, wherein the microcomputer electric water heater starts energizing the heater by skipping the peak shift after the peak shift is started. (6) A reset switch for clearing the memory contents of the microcomputer; and, if 200V AC power is supplied from the AC power supply, allowing the memory contents to be cleared according to the operation of the reset switch. 2. A reset stop circuit that prevents the memory contents from being cleared regardless of whether the reset switch is operated when the supply of 200V AC power from the AC power supply is stopped. 1), (
2), (3), (4) or (5) microcomputer electric water heater. (7) monitoring the output voltage of the backup power supply circuit;
When the output voltage falls below a predetermined voltage that makes it impossible to retain the memory contents of the microcomputer, when the supply of 200V AC power from the AC power source is started,
Claims (1), (2), and (2) further comprising a voltage monitoring circuit for clearing the memory contents of the microcomputer.
3), (4), (5) or (6) microcomputer electric water heater.