CN100508096C - Power Switching Devices for Household Appliances - Google Patents

Abstract

A power supply switch-over device of home appliance is prepared as utilizing switch-over device, controlled device, control device and power supply loop input end to form the first branch; using controlled device and power supply loop input end to form the second branch; controlling controlled device by control device to switch on the second branch and to switching off the first branch by switch-over device when the first branch is switched on by switch-over device then controlling on/off state of controlled device by detecting voltage of switch-over device with control device.

Description

Power Switching Devices for Household Appliances

technical field

The invention relates to a household appliance with an electric control board, in particular to a power switching device for the household appliance with an electric control board.

Background technique

Household appliances existing on the market generally have an electric control board. When the power plug is inserted into a charged socket, the electric control board is charged, and then the working state of the household appliance is controlled by the power switching device of the household appliance. Fig. 1 is a circuit diagram of a power switching device of a household appliance with an electric control board. Including the live wire L of the power plug, the neutral wire N, the power circuit and the power switching device; the power circuit is composed of a transformer T1, a rectifying device composed of rectifying diodes D1, D2, D3, D4, and a voltage stabilizing device W1; the power switching device Including switching device SW1 and single chip MCU. The primary side of the transformer T1 is connected to the live line L and the neutral line N of the power plug respectively, and the secondary side will input the voltage after the rectification device composed of diodes D1, D2, D3 and D4 and the voltage stabilizing device W1 into the single-chip MCU, and then the single-chip MCU scans The key state of the switching device SW1 controls the working state of the household appliance. When the household appliances need to work, press the switching device SW1, and the single-chip MCU scans that the switching device SW1 is on, and the electric control board enters the working state.

In the current control device of household appliances, the state of the switching device SW1 is scanned by the single-chip microcomputer, but because the single-chip microcomputer can only sense whether the switching device is pressed when it is charged and in the working state, there is still a standby function when the household appliance is not working. Consumption, a large amount of power consumption, resulting in a serious waste of energy.

Contents of the invention

The technical problem to be solved by the present invention is to provide a power switching device for household appliances, which can realize zero standby power consumption when the household appliances are not working.

In order to solve the above-mentioned technical problems, the present invention provides a power switching device for household appliances, the household appliances include a power plug and a power circuit connected to the power plug, and a receiver is connected between the live wire of the power plug and the input end of the power circuit. a control device; a switching device is connected between the live wire of the power plug and the controlled device, and the switching device is normally open and can be automatically reset; and between the controlled device and the input end of the power circuit There is a control device connected between them;

The switching device forms a first branch through the controlled device and the control device and the input end of the power circuit; the controlled device and the input end of the power circuit form a second branch;

When the switching device connects the first branch, the control device controls the controlled device to connect the second branch, and the switching device cuts off the first branch; then the The control device controls the on-off of the controlled device by detecting the voltage of the switching device.

Wherein, the controlled device is a relay, and the coil of the relay is connected between the switching device and the control device; the contact of the relay is connected to the live wire of the power plug and the input of the power circuit between the ends.

Wherein, the control device includes: a triode, the base of the triode is connected to the input end of the power circuit, the collector is connected to the coil of the relay, the emitter is connected to the ground, the switching device is connected to the relay The coil, the triode and the input end of the power circuit constitute the first branch circuit.

Wherein, the control device also includes a single-chip microcomputer, the power input end of the single-chip microcomputer is connected to the output end of the power circuit, the signal input end of the single-chip microcomputer is connected to the switching device, and the signal output end of the single-chip microcomputer is connected to the The base of the triode is connected;

After the single-chip microcomputer works, when the signal input terminal of the single-chip microcomputer is low level, the signal output terminal of the single-chip microcomputer is set as high level, to maintain the conducting state of the triode; when the signal input of the single-chip microcomputer When the terminal is high level, set the signal output terminal of the single chip microcomputer to low level to disconnect the triode.

In addition, the single-chip microcomputer can also realize the control process in the following manner: after the single-chip microcomputer works, when the signal input terminal of the single-chip microcomputer is high level, the signal output terminal of the single-chip microcomputer is set to high level to maintain The conduction state of the triode: when the signal input terminal of the single-chip microcomputer is at low level, the signal output terminal of the single-chip microcomputer is set at low level to disconnect the triode.

Wherein, the control device further includes: a pull-down resistor connected to the switching device.

Wherein, the contacts of the relay are normally open contacts, and the relay is a DC relay.

In addition, it also includes a resistor connected between the base of the triode and the power circuit, and a pull-down resistor connected to the base of the triode.

Compared with the prior art, the beneficial effect of the present invention is: the power switching device of the household appliance provided by the present invention, when the household appliance needs to work, the switching device is powered on, and then the control device detects the state of the switching device, which will be controlled The control device is turned on to supply power to the subsequent circuit, so that the household appliance can be started without the need for the household appliance to be charged all the time; Reset, thereby cutting off the path between the power plug and the subsequent stage circuit, so that there is no standby power consumption when the household appliance is not working, thereby realizing zero standby power consumption of the household appliance.

In addition, the control method of the control device in the present invention to the controlled device may be that the controlled device is turned on when the input terminal of the control device is at a high level, and the controlled device is turned on when the input terminal is at a low level. The device is disconnected; similarly, the control device can also be connected when the input terminal is at a low level, and the controlled device can be disconnected when the input terminal is at a high level, so that it is convenient for the user to choose an implementation method according to actual needs.

Further, in the present invention, a pull-down resistor is connected between the switching device and the input terminal of the single-chip microcomputer, so as to ensure accurate detection of the state change of the switching device when the single-chip microcomputer is working.

In addition, the power switching device of the present invention also has a diode to protect the power circuit of the single-chip microcomputer.

Description of drawings

Fig. 1 is the circuit schematic diagram of the power switching device of household appliance in the prior art;

Fig. 2 is the circuit principle diagram of the power switching device of household appliance in the present invention;

Fig. 3 is a schematic circuit diagram of the power switching device in the first embodiment.

Detailed ways

With the development of society, the number of household appliances is increasing day by day. Aiming at the problem that the existing household appliances still have standby power consumption when they are not working, the present invention proposes a power switching device. Electricity is zero. Household appliances usually detect the state of the power switch through a single-chip microcomputer. The core of the power switching device provided by the present invention is that the household appliances can be started without the single-chip microcomputer being charged all the time, and when the household appliances are not working, the power circuit can be cut off, so as to realize the power switch of the household appliances. zero standby loss.

Fig. 2 is a schematic diagram of a power control device provided by the present invention used in a household appliance. The figure includes a power plug 1, a power circuit 2 connected to the power plug, and a load 6 connected to the power circuit 2; A controlled device 3; a control device 4 connected to the input end of the controlled device 3 and the power circuit 2; and a switching device 5 connected to the power plug 1; the switching device 5 passes through the controlled The device 3 and the control device 4 form a first branch with the input end of the power circuit 2; the controlled device 3 and the input end of the power circuit 2 form a second branch;

The working principle of the power control device of the present invention is: the switching device 5 and the controlled device 3 are in a disconnected state when the household appliance is not working, and the circuit between the power plug 1 and the subsequent stage circuit is cut off, so that when the household appliance is not working Realize zero standby power consumption;

When household appliances need to work, the switch device 5 is manually pressed, and the first branch formed by the switch device 5, the controlled device 3, the control device 4 and the input end of the power circuit 2 is connected to the power plug 1 to form a circuit, and the power supply After the voltage is transformed, rectified, and stabilized by the power circuit 2, it supplies power to the loads of household appliances. After the switching device 5 is powered on, the power circuit supplies power to the control device 4, and the control device 4 starts to work. At this time, the control device 4 will send out The control signal closes the controlled device 3, so that the second branch composed of the input end of the power circuit 2 connected to the controlled device 3 and the power plug 1 also form a circuit, so the power supply voltage passes through the branch connected to the controlled device 3 The circuit supplies power to the load; and the switching device 5 switches back to the original state after being powered on, and the control device 4 detects the state of the switching device 5 at this time, and outputs a control signal to ensure the closed state of the controlled device 3 .

When the household appliance is turned off, press the switching device 5 again, and now the control device 4 detects the state of the switching device 5, and switches the connection between the controlled device 3 and the power plug 1. After the switching device 5 is pressed, it automatically switches back to the original state. Therefore, the switching device 5 and the controlled device 3 switch the circuit between the power plug 1 and the subsequent circuit, and the household appliances stop working. Since it does not form a loop, it achieves zero standby loss.

In the present invention, the controlled device is a relay, the coil of the relay is connected to the first branch; the contact of the relay is connected to the second branch.

The control device includes: a triode, the base of the triode is connected to the power circuit, the collector is connected to the coil of the relay, the emitter is connected to the ground, the switching device is connected to the coil of the relay, the triode and The input end of the power circuit constitutes the first branch; the control device also includes a single-chip microcomputer, the signal input end of the single-chip microcomputer is connected to the switching device, and the signal output end of the single-chip microcomputer is connected to the base of the triode ; There are the following two implementations for the process of the single-chip microcomputer controlling the relay work:

The first one is, after the single-chip microcomputer works, when the signal input terminal of the single-chip microcomputer is low level, the signal output terminal of the single-chip microcomputer is set to high level, to maintain the conduction state of the triode; When the signal input end of the single-chip microcomputer is at a high level, the signal output end of the single-chip microcomputer is set at a low level to disconnect the triode.

In addition, after the single-chip microcomputer works, when the signal input terminal of the single-chip microcomputer is at a high level, the signal output terminal of the single-chip microcomputer is set at a high level to maintain the conduction state of the triode; When the signal input terminal of the single-chip microcomputer is at low level, the signal output terminal of the single-chip microcomputer is set at low level to disconnect the triode.

The contact of the switching device of the present invention is a normally open contact, and an elastic switch is selected.

Since the input terminal of the single-chip microcomputer is suspended when the switching device is disconnected, in order to ensure that the input terminal of the single-chip microcomputer can accurately detect the level of the input terminal, the present invention also includes a pull-down resistor connected to the switching device.

The contacts of the relay are normally open contacts, and the relay is a DC relay. In order to provide DC power for the DC relay, the voltage passing through the switching device needs to be rectified by the rectifier diode and DC-blocked by the DC-blocking capacitor.

When household appliances are required to work, since the switching device needs to communicate with the triode and the coil with the power circuit, it is necessary to provide a conduction voltage for the triode. The method provided by the invention is to connect a resistor between the base of the triode and the power circuit, At the same time, a pull-down resistor is connected to the base of the triode, and the pull-down resistor acts as a current limiter to prevent breakdown of the triode.

Taking the washing machine as an example, the implementation process and working principle of the present invention will be described in detail below.

Embodiment 1: In this embodiment, the switching device is an elastic switch, which serves as a power button for starting and shutting down the washing machine, and the controlled device is a DC relay.

Fig. 3 is a schematic diagram of the power switching device of the washing machine. K1 is a relay, T1 is a transformer, L is the live wire of the plug, N is the neutral wire of the plug, SW1 is a power button switch, one end of SW1 is connected to the live wire L of the plug, and the other end is connected to the coil of the relay K1; the transformer T1 and The rectifying device composed of rectifying diodes D1, D2, D3, and D4 and the voltage stabilizing device W1 form a power circuit, which supplies power for the power supply VDD of the single-chip MCU, the relay power supply VCC and the load. In order to enable the signal input terminal INI of the single-chip MCU to detect the state of SW1, connect the spring of the elastic switch SW1 to the signal input terminal INI of the single-chip MCU, so that when SW1 is pressed, the normally open contact is connected, and when SW1 is released The normally open contacts are automatically disconnected. In order to enable the input signal of the signal input terminal INI to accurately detect the state of SW1 under different states of SW1, a resistor R5, a pull-down resistor R4, and a capacitor C3 for filtering are connected between SW1 and the input terminal of the single-chip MCU. In addition, a protection diode D8 and a resistor R6 are also provided between the signal output terminal of the MCU and the power supply terminal VDD. In order to be able to control the relay K1, a triode N1 is set between the signal output terminal OUT1 of the single-chip MCU and the relay K1, the base of the triode N1 is connected to the signal output terminal OUT1, the emitter is connected to the ground, and the collector is connected to the ground. The coil of the relay K1 is connected. In order to provide the conduction voltage for the transistor, a resistor R1 is also connected between the power supply VCC of the relay and the base of the transistor N1, and a resistor R2 that acts as a voltage divider between the base of N1 and the ground. Since the relay K1 in this embodiment is a DC relay, the voltage passing through the SW1 needs to be rectified by the rectifier diode D6 and the DC blocking function of the capacitor E3. In addition, it also includes a Zener diode VD1 connected to the relay power supply for voltage stabilization.

The working principle of the above power control device is as follows.

When the power plugs L and N of the washing machine are connected to the power supply and the power button SW1 is not pressed, because K1 of the electric control board is not closed, L and N do not form a circuit, so there is no standby power consumption. When the washing machine needs to work, press the power button SW1, the normally open contact of SW1 is closed, and the L of the AC power supply passes through SWI, the rectifier diode D6, the coil of the relay K1, the triode N1, and the resistor R3 to the zero line N of the power supply to form a loop. , the driving relay K1 is closed, so that the live line L of the power supply, the primary side of the transformer T1 and the neutral line N form a loop, and the transformer T1 obtains a lower AC voltage after transformation to supply power to the load. At the same time, the voltage stabilizing device W1 supplies power to the input terminal of the single-chip MCU power supply. Therefore, when the single-chip MCU is powered on, the single-chip MCU will send a high-level electrical signal to the transistor N1 through the output terminal OUT1. After the transistor N1 is turned on, the coil of the relay K1 is controlled. In this way, the contact K1 of the relay is closed to supply power to the subsequent circuit. The power button SW1 is an elastic switch, so it automatically resets after being pressed, and is disconnected from the live wire L of the power plug. Due to the function of the resistor R5 and the pull-down resistor R4, The input signal of the input terminal IN1 of the single-chip MCU is low level, the output signal of the control signal output terminal OUT1 remains high level, and the transistor N1 maintains the conduction state, so even if the power button SW1 is reset, the subsequent circuit can still continue to be powered. The entire circuit remains powered.

When the washing machine is stopped, press the power button SW1 again, and the normally open contact of the power button SW1 will be closed, so that the signal input terminal IN1 of the single-chip microcomputer will change from low level to high level, and at this time, the output terminal OUT1 of the single-chip microcomputer is controlled to output Low level, the transistor N1 is disconnected, thereby disconnecting the relay K1. Since the power button SW1 has been released at this time, the live wire L of the AC circuit, the transformer T1, and the neutral wire N cannot form a circuit. The control coil loses power, since we use the normally open contact of the relay K1, the purpose of shutting off the power supply is realized.

In addition, another realization scheme of the present invention can connect the power input terminal of the single-chip microcomputer to a negative voltage. At this time, the control process for the single-chip microcomputer is, when the single-chip microcomputer is powered on, it sends a high level to the triode immediately, and it is connected; When household appliances are required to work, since the voltage of the single-chip microcomputer is higher than the pull-down resistor, the input terminal of the single-chip microcomputer inputs a high level, and the control signal output terminal of the single-chip microcomputer outputs a high level at this time to keep the triode in a conducting state; when it is necessary to turn off the household appliance, The signal input level of the single-chip microcomputer is low level, at this time, the control signal output terminal outputs a low level to disconnect the triode so as to cut off the power circuit. Since the working process is the same as that of the first embodiment, only the control signal of the signal input terminal to the signal output terminal changes, so no more details are given here.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (8)

1. A power switching device for a household appliance, said household appliance comprising a power plug and a power circuit connected to the power plug, characterized in that: A controlled device is connected between the live wire of the power plug and the input end of the power circuit; A switching device is connected between the live wire of the power plug and the controlled device, and the switching device is normally open and can be reset automatically; and A control device is connected between the controlled device and the input end of the power circuit; The switching device forms a first branch through the controlled device and the control device and the input end of the power circuit; the controlled device and the input end of the power circuit form a second branch; When the switching device connects the first branch, the control device controls the controlled device to connect the second branch, and the switching device cuts off the first branch; then the The control device controls the on-off of the controlled device by detecting the voltage of the switching device. 2. The power switching device according to claim 1, characterized in that: the controlled device is a relay, and the coil of the relay is connected between the switching device and the control device; the contacts of the relay It is connected between the fire wire of the power plug and the input end of the power circuit. 3. The power switching device according to claim 2, wherein the control device comprises: a triode, the base of the triode is connected to the input end of the power circuit, and the collector is connected to the coil of the relay , the emitter is connected to the ground, and the switching device, the coil of the relay, the triode and the input end of the power circuit form the first branch circuit. 4. The power switching device according to claim 3, characterized in that: the control device includes a single-chip microcomputer, the power input end of the single-chip microcomputer is connected to the output end of the power circuit, and the signal input end of the single-chip microcomputer is connected to the The switching device is connected, and the signal output terminal of the single-chip microcomputer is connected with the base of the triode; After the single-chip microcomputer works, when the signal input terminal of the single-chip microcomputer is low level, the signal output terminal of the single-chip microcomputer is set as high level, to maintain the conducting state of the triode; when the signal input of the single-chip microcomputer When the terminal is high level, set the signal output terminal of the single chip microcomputer to low level to disconnect the triode. 5. The power switching device according to claim 3, wherein the control device includes a single-chip microcomputer, the signal input end of the single-chip microcomputer is connected to the switching device, and the signal output end of the single-chip microcomputer is connected to the triode base connection; After the single-chip microcomputer works, when the signal input end of the single-chip microcomputer is high level, the signal output end of the single-chip microcomputer is set as high level, to maintain the conducting state of the triode; when the signal input end of the single-chip microcomputer is low When the level is low, set the signal output terminal of the single-chip microcomputer to low level to disconnect the triode. 6. The power switching device according to claim 4 or 5, wherein the control device further comprises: a pull-down resistor connected to the switching device. 7. The power switching device according to claim 4 or 5, characterized in that the contacts of the relay are normally open contacts, and the relay is a DC relay. 8. The power switching device according to claim 4 or 5, further comprising a resistor connected between the base of the triode and the power circuit, and a pull-down resistor connected to the base of the triode .

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