CN105305857A - Capacitive switch safe isolation program-controlled power supply circuit - Google Patents

Abstract

The invention discloses a capacitive switch safety isolation program-controlled power supply circuit, which includes a bridge rectifier circuit, a single chip microcomputer, a capacitive program-controlled step-down circuit, a switch circuit, and a bridge rectifier circuit composed of triodes Q1, Q3 and diodes D2 and D3. The base is connected to the single-chip microcomputer, and the capacitive program-controlled step-down circuit includes capacitors C2, C3, C4 and transistors Q4 and Q5 to form a DC step-by-step step-down. The bases of the transistors Q4 and Q5 are connected to the single-chip computer, and the switch circuit includes two sets of program-controlled synchronous switches. The first set of switches connects the output end of the bridge rectifier circuit, the capacitor C2 and the input end of the transistor Q4, the second set of switches connects the capacitor C2 and the output end of the transistor Q4, the capacitor C3 and the input end of the transistor Q5, and two sets of program-controlled synchronous switches not closed at the same time. The invention replaces the bulky power transformer with a capacitive program-controlled step-down circuit, improves the power factor of the commercial power, and saves a lot of electric energy.

Description

Capacitive switch safety isolation program-controlled power supply circuit

technical field

The invention relates to the technical field of power circuits, and more specifically relates to a capacitive switch safety isolation program-controlled power circuit.

Background technique

The traditional power supply circuit is inseparable from the safety isolation transformer, which can prevent the electric shock risk of the subsequent stage circuit while stepping down the voltage. Transformers are inductive components. All walks of life in the society use a large number of inductive reactance electrical appliances, such as: motors, injection molding machines, incubators, electric water heaters, electric heaters, induction cookers, electric kettles and so on. Extensive use of inductive reactance electrical appliances will cause huge waste of energy for the country's mains power supply, because inductive circuits will increase the reactive power of the mains and reduce the power factor. If a capacitive circuit is used to compensate (neutralize) the excess inductance in the inductive circuit, theoretically it can definitely increase the active power of the mains power and reduce the reactive power, thereby improving the power factor of the mains power supply. However, there is no public report in the relevant literature at present.

Contents of the invention

The technical problem to be solved by the present invention is to provide a capacitive switch safety isolation program-controlled power supply circuit in view of the problem of reducing the power factor of the current safety isolation transformer, which cancels the safety isolation transformer and adopts a capacitor for voltage reduction. Safety isolation is carried out to overcome the deficiencies of existing technologies.

The technical solution adopted by the present invention to solve the technical problem is: a capacitive switch safety isolation program-controlled power supply circuit, including a bridge rectifier circuit, a single-chip microcomputer, and a capacitive program-controlled step-down circuit, a switch circuit, and the bridge rectifier circuit is composed of a triode Composed of Q1, Q3 and diodes D2, D3, the bases of transistors Q1, Q3 are connected to the microcontroller, the capacitive program-controlled step-down circuit includes capacitors C2, C3, C4 and transistors Q4, Q5, and the capacitors C2, C3, C4 form a DC step-by-step step-down, the bases of transistors Q4 and Q5 are connected to the single-chip microcomputer, the switch circuit includes two sets of program-controlled synchronous switches, and the first group of program-controlled synchronous switches K1 and K2 are connected to the output terminal of the bridge rectifier circuit, capacitor C2 and the input terminal of the transistor Q4, so that the bridge rectifier circuit and the subsequent stage circuit can be disconnected by the first group of program-controlled synchronous switches, and the second group of program-controlled synchronous switches K3 and K4 are connected to the output terminal of the capacitor C2 and the transistor Q4, capacitor C3 and the transistor At the input end of Q5, two sets of program-controlled synchronous switches are not closed at the same time.

The first output voltage detection circuit is connected to the input end of the first group of program-controlled synchronous switches. The output voltage detection circuit is composed of resistors R7, R8, and R9, and the resistor R8 is connected to the single-chip microcomputer.

It also includes a backup power supply circuit, the backup power supply circuit is composed of a transistor Q2 and a capacitor C1, and the base of the transistor Q2 is connected to the single-chip microcomputer.

The output end of the capacitor C4 is connected to a second output voltage detection circuit, the second output voltage detection circuit is composed of resistors R12, R13, and R14, and the resistor R13 is connected to the single-chip microcomputer at the same time.

It also includes a power supply voltage detection circuit for time synchronization correction, and the power supply voltage detection circuit is composed of a diode D1, resistors R3, R4, and R5.

Compared with prior art, the beneficial effect of the present invention is:

According to the characteristics of capacitor energy storage, the invention adopts a bridge switch structure to realize the purpose of outputting a safe and isolated power supply. The traditional transformer step-down circuit is replaced by a capacitive program-controlled step-down circuit, and the bulky power transformer is eliminated, which not only saves costs, but also improves the power factor of the mains power, saving a lot of power for the country and saving power for the power circuit. hardware space.

The invention easily realizes the purpose of power supply safety isolation through the bridge switch structure and application of software programming technology.

Description of drawings

Fig. 1 is a circuit diagram of a capacitive switch safety isolation program-controlled power supply circuit of the present invention.

Fig. 2 is a schematic diagram of the single-chip microcomputer port structure of the capacitive switch safety isolation program-controlled power supply circuit of the present invention.

FIG. 3 is a structural schematic diagram of Embodiment 1 of the switching circuit of the present invention.

FIG. 4 is a schematic structural diagram of Embodiment 2 of the switching circuit of the present invention.

Fig. 5 is a waveform diagram of the rectification circuit of the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

Referring to Figures 1-5, the capacitive switch safety isolation program-controlled power supply circuit of the present invention includes a bridge rectifier circuit 1, a single-chip microcomputer, a capacitive program-controlled step-down circuit, and a switch circuit 3. The bridge rectifier circuit consists of transistors Q1, Composed of Q3 and diodes D2 and D3, the bases of transistors Q1 and Q3 are connected to the single-chip microcomputer. The capacitive program-controlled step-down circuit includes capacitors C2, C3, C4 and transistors Q4 and Q5, and the capacitors C2, C3 and C4 form a DC step-by-step step-down, the bases of the transistors Q4 and Q5 are connected to the microcontroller, the switch circuit includes two sets of program-controlled synchronous switches, the first group of program-controlled synchronous switches K1 and K2 are connected to the output end of the bridge rectifier circuit, the capacitor C2 and the triode The input terminal of Q4, so that the bridge rectifier circuit and the subsequent stage circuit can be disconnected by the first group of program-controlled synchronous switches, and the second group of program-controlled synchronous switches K3 and K4 connect the output terminal of capacitor C2 and transistor Q4, capacitor C3 and transistor Q5. At the input end, the two sets of program-controlled synchronous switches are not closed at the same time. The traditional bridge rectifier circuit is composed of diodes. The invention breaks the convention and forms a bridge rectifier through triodes and D2 and D3, which is controlled by a single-chip microcomputer program.

The first output voltage detection circuit 2 is connected to the input end of the first group of program-controlled synchronous switches. The output voltage detection circuit is composed of resistors R7, R8, and R9, and the resistor R8 is connected to the single-chip microcomputer. The present invention also includes a backup power supply circuit, the backup power supply circuit is composed of a triode Q2 and a capacitor C1, and the base of the triode Q2 is connected to the single-chip microcomputer. When the voltage output by the bridge rectifier circuit 1 is insufficient, the program control system activates the backup power supply circuit to supplement the deficiency of the bridge rectifier circuit and make the voltage output more stable.

The output end of the capacitor C4 is connected to the second output voltage detection circuit 4, the second output voltage detection circuit is composed of resistors R12, R13, R14, and the resistor R13 is connected to the single chip microcomputer at the same time. The present invention also includes a power supply voltage detection circuit for time synchronization correction, and the power supply voltage detection circuit is composed of a diode D1, resistors R3, R4, and R5.

The invention realizes the safety of the program-controlled switch through a plurality of functional circuits such as a single-chip microcomputer chip control program, a high-voltage transistor program-controlled rectifier circuit, a capacitor step-down program-controlled circuit, a program-controlled bridge switch safety isolation circuit, a low-frequency voltage stabilizing program-controlled circuit, and a PWM pulse width modulation circuit. The role of isolated power. Transistors Q1, Q3 and diodes D2, D3 form a program-controlled rectifier circuit. The working process of the program-controlled rectification is as follows: Q1, Q3, D2 and D3 are the same as the traditional bridge full-wave rectification circuit in principle, the difference is that Q1 and Q3 are controlled by the single-chip microcomputer program. The traditional bridge rectifier circuit is an open rectification composed of four diodes, which is not controlled.

Capacitors C2, C3, C4 and transistors Q4, Q5 form a capacitive DC step-down circuit, a low frequency voltage stabilizing program control circuit and a PWM pulse width modulation circuit. Switches K1-K4 form a bridge switch safety isolation program-controlled circuit. The working process is described as follows: After being rectified by the previous rectification circuit, the circuit charges the capacitor C2 from time to time, and the voltage on C2 can generally be designed to be higher, such as: 100-300VDC. The specific voltage value is determined by calculation according to the size of the load. Capacitors C2, C3 and transistor Q4 are composed of a DC step-down circuit, which steps down through the principle of PWM pulse width modulation. Its pulse width is also controlled by programs B4 and B5.

The working process of the four switches K1-K4 is: when K1 and K2 are turned on, K3 and K4 must be turned off, at this time, the rectifier circuit charges the capacitor C2; when K1 and K2 are turned off, K3 and K4 can be turned on or off Closed, generally in a closed state. At this time, the rectifier circuit stops charging C2, starts transistors Q4 and Q5, and controls the opening and closing of transistors Q4 and Q5 through ports B4 and B5 through the program, and charges capacitors C3 and C4 respectively by means of PWM pulse width modulation. Since K1 and K2 are closed at this time, the front AC power circuit is completely isolated, so the rear DC power circuit is safely isolated. Switches K1 and K2, K3 and K4 are two groups of switches with different functions, and the two groups of switches cannot be closed at the same time at any time. K1-K4 switches can choose optocoupler, photoelectric switch or relay according to the needs of the application. If you choose a relay, you must consider the coordination between the life of the relay and the operating frequency. See Figure 3-4, the four switches K1-K4 are also controlled by the single-chip microcomputer program, and are controlled by VK1-VK4 respectively. The four switches can use relay type control switches (see Figure 3) or optocoupler switches (see Figure 4).

It can be seen from Figure 5 that the two triodes Q1 and Q3 are controlled on and off by ports B1 and B3 through the program according to the design load requirements. Among them, the triode Q2 and the capacitor C1 form a backup power supply circuit, which is also controlled by the program through the port B2. Resistors R7, R8, and R9 form an output voltage detection circuit, which is also controlled by the program through port RC2. When the output power of the rectifier circuit is not enough, and it happens to be at the zero crossing point of the power supply or when the power supply voltage U1 is less than UO, the backup is started through the program. power circuit. This avoids excessive fluctuations in the output voltage. Diode D1, and resistors R3, R4, R5 form a power supply voltage detection circuit, which plays the role of time synchronization correction and prevents the single chip microcomputer from losing control due to time asynchrony.

The above disclosure is only a specific embodiment of the present invention, and does not constitute a limitation to the protection scope of the present invention. For those of ordinary skill in the technical field of the present invention, without departing from the overall concept of the present invention, according to the technical solution of the present invention All changes and substitutions that do not require creative labor should fall within the protection scope of the present invention.

Claims (5)

1. capacitance-type switch Secure isolation programmable power supply circuit, comprise bridge rectifier, single-chip microcomputer, it is characterized in that: also comprise condenser type program controlled hypertension circuit, switching circuit, described bridge rectifier is by triode Q1, Q3 and diode D2, D3 forms, triode Q1, the base stage of Q3 connects single-chip microcomputer, described condenser type program controlled hypertension circuit comprises electric capacity C2, C3, C4 and triode Q4, Q5, by electric capacity C2, C3, C4 forms direct current step pressure reducing, triode Q4, the base stage of Q5 connects described single-chip microcomputer, described switching circuit comprises two groups of program control synchro switches, first group of program control synchro switch K1, K2 connects the output of described bridge rectifier, the input of electric capacity C2 and triode Q4, thus bridge rectifier and late-class circuit can be disconnected by first group of program control synchro switch, second group of program control synchro switch K3, K4 connects the output of electric capacity C2 and triode Q4, the input of electric capacity C3 and triode Q5, two groups of program control synchro switches are closed time different.

2. capacitance-type switch Secure isolation programmable power supply circuit according to claim 1, it is characterized in that: connect the first output voltage detecting circuit at the input of described first group of program control synchro switch, described output voltage detecting circuit is made up of resistance R7, R8, R9, and resistance R8 connects described single-chip microcomputer.

3. capacitance-type switch Secure isolation programmable power supply circuit according to claim 2, it is characterized in that: also comprise stand-by power supply circuit, described stand-by power supply circuit is made up of triode Q2, electric capacity C1, and the base stage of triode Q2 connects described single-chip microcomputer.

4. capacitance-type switch Secure isolation programmable power supply circuit according to claim 1, it is characterized in that: connect the second output voltage detecting circuit at the output of electric capacity C4, described second output voltage detecting circuit is made up of resistance R12, R13, R14, and resistance R13 connects described single-chip microcomputer simultaneously.

5. capacitance-type switch Secure isolation programmable power supply circuit according to claim 1, it is characterized in that: also comprise the voltage detection circuit for time synchronism calibration, described voltage detection circuit is made up of diode D1, resistance R3, R4, R5.