introduction
The ecological deterioration caused by the global energy crisis and all kinds of bad realities are forcing us to work hard to increase revenue and reduce expenditure. Modern household appliances are changing with each passing day, and science and technology workers spare no effort to develop more advanced and energy-saving electrical equipment and power outlets. A variety of sockets with energy-saving functions have appeared on the market to reduce the standby power consumption of various appliances.
In daily life, we found that there are some cases: the power consumption of a single plug is somewhat troublesome; after the equipment such as speakers is used up on the computer, it is often forgotten to turn off; when people leave the room, they forget to turn off the computer TV, like This causes it to consume electricity for a long time, waste energy, and damage the machine. So this paper designed an energy-saving human body sensor switch to solve this energy consumption problem.
According to the actual use function, the power outlets are mainly divided into the following types: ordinary power outlets, protective power outlets, and energy-saving outlets. Protective power outlets can be classified into overload protection, lightning protection and electric shock protection. Energy-saving sockets include computer energy-saving sockets, TV energy-saving sockets and human body energy-saving sockets.
1.1 ordinary power socket
A common power outlet is a device that is connected from a power source to an appliance and that uses an appliance to turn on the power. In the electrical industry, it is also called "similar to household electrical equipment", it only has the power-on function, no other auxiliary functions.
1.2 Protective power socket
Over-protection socket: In order to protect the user's personal safety and property safety, through a current overload protection circuit, when the current on the socket is greater than the rated current, the power will be automatically cut off. After the overload fault is eliminated, it can be used continuously by manual reset. It is more convenient to use without replacing the fuse.
Lightning protection socket: The principle is the same as the overload protection. When the lightning protection is caused by the built-in lightning protection device, the power supply of the socket is automatically cut off and the current is automatically introduced into the earth to protect the safety of the user and the electrical appliance.
1.3 Energy-saving socket
Energy-saving sockets mainly need to solve the problem of standby energy consumption and power-on energy consumption. People have developed a class of energy-saving sockets such as Eurasian protection sources and small housekeeper energy-saving sockets for standby power consumption. It mainly controls the current of the main unit according to the change of the current of the coil, and controls the operation of the slave through the processing of the integrated circuit and the on/off of the relay. For example, the printer, scanner, and audio are automatically turned off while the computer is turned off. The problem of power-on energy consumption is determined by the electrical appliance itself, but it can be actively judged and turned on or off through the energy-saving socket, thereby achieving the purpose of energy saving.
The computer energy-saving socket can automatically cut off the power of external devices such as monitors, printers, and speakers after the computer is turned off. The user can use the timed shutdown software to set the shutdown at any time. The set time is up, the computer host automatically shuts down, and other devices can also automatically power off. The computer energy-saving socket not only solves the problem of wasteful power consumption during standby, but also greatly reduces the working time of the electrical appliance and effectively prolongs the life of the electrical equipment. After the main unit is turned off, other electrical appliances connected to the socket are completely cut off to prevent damage to the appliance during overload, short circuit and lightning strikes.
2.1 Pyroelectric effect
If the surface of some ferroelectric substances is changed, as the temperature rises or falls, a change in charge occurs on the surface of these substances. This phenomenon is called pyroelectric effect. The window of the pyroelectric infrared sensor receives light, and the filter suppresses white light in nature, and only infrared rays of a specific wavelength can be irradiated onto the pyroelectric element through the filter. When the upper and lower surfaces of the pyroelectric element are irradiated differently, electrons are generated to form a current, and the current is passed through the field effect transistor to amplify the output voltage signal. The pyroelectric sensitivity of the pyroelectric infrared sensor is 0.2 to 20 μm, and the infrared wavelength of the human body is about 9 to 10 μm. Therefore, a bandpass filter with a wavelength range of 8 to 11 μm is used to filter out unwanted light waves.
2.2 pyroelectric infrared sensor device
Since the pyroelectric element itself has a limited detection capability and requires an auxiliary circuit, it is inferior in practicability. Therefore, manufacturers generally provide complete sensor devices instead of simple sensor components. The multi-function sensor has a timer inside; the general-purpose type is small in size and low in price, and the sensor is internally provided with a filter circuit to avoid false alarms. Users of these devices can arbitrarily set the sensitivity and timing by adjusting the resistors and capacitors. These sensor units are easy to install on the lighting unit, allowing it to work only at night or for luminaire control. The sensor's sensor detection distance is 5m. As long as the human body temperature is greater than the ambient temperature of 4 ° C.
2.3 sensing signal processing circuit
The sensing signal processing circuit is designed using a BISS0001 chip with an independent high input impedance operational amplifier. BISS0001 is a high performance sensing signal processing integrated circuit. It is equipped with a pyroelectric infrared sensor and a small number of external components to form a passive pyroelectric infrared switch. BISS0001 chip operating voltage is 3 ~ 6 V, 5 V is recommended; when the operating voltage is 5 V, the output drive current corresponds to 10 mA; operating temperature is -20 ° C ~ 70 ° C; storage temperature -40 ° C ~ 125 ° C .
2.4 Power section
The 220 V mains output is 5 V AC voltage through the transformer, rectified by the bridge reactor, and then filtered by the capacitor and then sent to the three-terminal regulator 7805. The 5 V DC voltage output by the 7805 pin is then filtered to obtain a stable voltage. When the switch S is closed, the power supply can supply power to the lower stage circuit.
2.5 Working principle and selection of electromagnetic relay
Electromagnetic relays are generally composed of a core, a coil, an armature, a contact spring, and the like. As long as a certain voltage is applied to both ends of the coil, a certain current flows in the coil, thereby generating an electromagnetic effect, and the armature attracts the iron core against the pulling force of the return spring under the action of the electromagnetic force attraction. When the coil is de-energized, the electromagnetic suction also disappears, and the armature pulls under the reaction force of the spring.
The power supply voltage of the control circuit is 5V, and the controlled circuit is 220V for the household circuit. Considering that a large number of power consumers may be connected to the socket, a relay with a maximum current of at least 10 A must be selected. This relay needs to be installed in a small-sized socket box, and an ultra-small relay product is required. In summary, we have chosen the Taiming brand soldering foot type PCB relay with ultra-small size and stable performance, the model is JQC-3F (T73) DC5V10A.
2.6 socket circuit design
The pyroelectric sensor senses the infrared rays radiated by the human body to determine whether someone is present, and then amplifies and outputs a control signal to control the relay, and then controls the on and off of the electrical appliance through the relay, thereby achieving the purpose of energy saving. Figure 1 is a block diagram of the circuit composition of this design.
I use pyroelectric sensor RE200B, the sensor signal processing circuit is designed with BISS0001 chip with independent high input impedance operational amplifier. The internal bidirectional discriminator can effectively suppress interference. Built-in delay time timer and blocking time timer . The relay uses the commonly used Taiming JQC-3FDC5V10A relay.
After testing, the circuit can detect the human body within 10m under the condition of the sensor and Fresnel, and make the switching action, but pay attention to the perspective of the sensor on the outward side. The circuit can also set the delay time to control the appliance to switch at a certain time after the person or away.
3 SummaryInductive energy-saving socket design can sense the human body within 10 meters radius and control the electrical appliances. It has the characteristics of energy saving, humanization and ease of use, which meets the requirements of the times. This design is worry-free and energy-saving, but its load capacity is not very large, anti-interference ability is not strong enough, further research and design are needed, and friends are welcome to communicate and guide.
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