Circuit structure for controlling heating power

Abstract

The utility model relates to a circuit structure for controlling heating power, which comprises a microcontroller circuit, the microcontroller circuit is connected with the input end of a digital-analog conversion circuit, the output end of the digital-analog conversion circuit is connected with the input end of a voltage follower circuit, and the output end of the voltage follower circuit is connected with the output end of the digital-analog conversion circuit. The output end of the voltage follower circuit is respectively connected with the switching power supply output end divider resistance circuit and the operational amplifier circuit output end divider resistance circuit through the operational amplifier circuit; the band enabling DC / DC switching power supply circuit is respectively connected with the switching power supply output end divider resistance circuit, the operational amplifier circuit output end divider resistance circuit, the Vout and one end of the heating resistor, and the switching power supply output end divider resistance circuit is respectively connected with the band enabling DC / DC switching power supply circuit, the Vout and one end of the heating resistor. The Vout is connected with one end of the heating resistor, and the other end of the heating resistor is grounded.

Description

Technical Field

[0001] The utility model belongs to the technical field of automatic temperature control, and in particular relates to a circuit structure for controlling heating power. Background Art

[0002] In the field of automatic control, temperature automatic control systems generally use a switch on-off method or a duty cycle adjustment method to start and stop heating. By continuously switching on and off, as well as the length of time on and off, the power supply is increased or decreased, thereby achieving regulation of heating power.

[0003] However, continuous switching will bring some problems such as electromagnetic interference and high transient power. Although the control method is simple, it is relatively rough and not gentle enough, which will have a certain impact on some application scenarios. It has relatively high requirements on the life of the switching devices and the power of the power supply. Utility Model Content

[0004] The utility model aims at the deficiencies of the prior art and provides a circuit structure for controlling heating power.

[0005] The utility model is realized by the following technical solutions:

[0006] A circuit structure for controlling heating power, comprising:

[0007] A microcontroller circuit for outputting different control drive signals;

[0008] A digital-to-analog conversion circuit, used for receiving a control drive signal from a microcontroller circuit and then outputting different voltage signals;

[0009] A DC / DC switching power supply circuit with enable is used to output stable voltage and current, output adjustable voltage according to the sampling signal, and control the opening and closing of the circuit through the enable signal;

[0010] The voltage-dividing resistor circuit at the output end of the switching power supply is used to divide the output voltage;

[0011] The voltage follower circuit transmits the voltage of the digital-to-analog conversion circuit;

[0012] An operational amplifier circuit is used to process an input signal and output a corresponding voltage signal;

[0013] The voltage-dividing resistor circuit at the output end of the operational amplifier circuit is used to divide the output voltage of the operational amplifier circuit;

[0014] Heating resistor, used to output different heating power when loaded with different voltages;

[0015] The microcontroller circuit is connected to the input end of the digital-to-analog conversion circuit, the output end of the digital-to-analog conversion circuit is connected to the input end of the voltage follower circuit, the output end of the voltage follower circuit is respectively connected to the voltage-dividing resistor circuit at the output end of the switching power supply and the voltage-dividing resistor circuit at the output end of the operational amplifier circuit through the operational amplifier circuit, the enabled DC / DC switching power supply circuit is respectively connected to the voltage-dividing resistor circuit at the output end of the switching power supply, the voltage-dividing resistor circuit at the output end of the operational amplifier circuit, Vout and one end of the heating resistor, the voltage-dividing resistor circuit at the output end of the switching power supply is respectively connected to the enabled DC / DC switching power supply circuit, Vout and one end of the heating resistor, the Vout is connected to one end of the heating resistor, and the other end of the heating resistor is grounded.

[0016] Furthermore, the specific structure of the voltage follower circuit is: the output end of the digital-to-analog conversion circuit is connected to one end of resistor R8, the other end of resistor R8 is connected to the "+" end of the operational amplifier U2.1, and the "-" end of the operational amplifier U2.1 and the output end of the operational amplifier U2.1 are both connected to the operational amplifier circuit.

[0017] Furthermore, the specific structure of the operational amplifier circuit is as follows: the output end of the voltage follower circuit is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the "+" end of the operational amplifier U2.2, the "-" end of the operational amplifier U2.2 is respectively connected to one end of the resistor R3 and the resistor R6, the other end of the resistor R3 is connected to the voltage-dividing resistor circuit at the output end of the switching power supply, and the output end of the operational amplifier U2.2 and the other end of the resistor R6 are both connected to the voltage-dividing resistor circuit at the output end of the operational amplifier circuit.

[0018] Furthermore, the specific structure of the voltage-dividing resistor circuit at the output end of the operational amplifier circuit is: the operational amplifier circuit is connected to one end of the resistor R1, the other end of the resistor R1 is respectively connected to the enabled DC / DC switching power supply circuit and one end of the resistor R2, and the other end of the resistor R2 is grounded.

[0019] Furthermore, the specific structure of the voltage-dividing resistor circuit at the output end of the switching power supply is: one end of the resistor R3 is respectively connected to one end of the resistor R5 and the resistor R7, the other end of the resistor R5 is grounded, and the other end of the resistor R7 is respectively connected to the enabled DC / DC switching power supply circuit, Vout and one end of the heating resistor.

[0020] Furthermore, the specific structure of the enabled DC / DC switching power supply circuit is as follows: the voltage-dividing resistor circuit at the output end of the operational amplifier circuit is connected to the VSENSE pin of the switching power supply controller U1, the enable pin ENA of the switching power supply controller U1 is connected to the enable signal Enable, the VIN pin of the switching power supply controller U1 is connected to the input voltage Vin, the GDN pin of the switching power supply controller U1 is grounded, the PH pin of the switching power supply controller U1 is respectively connected to one end of the inductor L1 and the negative electrode of the Schottky diode D1, the positive electrode of the Schottky diode D1 is connected to one end of the capacitor C1 and is grounded, the other end of the inductor L1 is respectively connected to the other end of the capacitor C1, the voltage-dividing resistor circuit at the output end of the switching power supply, one end of the heating resistor and Vout, and the model of the switching power supply controller U1 is TPS5450.

[0021] Compared with the prior art, the utility model has the following beneficial effects:

[0022] The utility model provides a circuit structure for controlling heating power, comprising: a DC / DC switching power supply circuit with enable, a voltage follower circuit, an operational amplifier circuit, a digital-to-analog conversion circuit, a microcontroller circuit, two voltage-dividing resistor circuits, and a heating resistor; the implementation method is to control the digital-to-analog conversion circuit to output a changing voltage signal through the microcontroller circuit, and the voltage signal output by the digital-to-analog conversion circuit is output to the "+" end of the operational amplifier circuit through the voltage follower circuit; the output of the switching power supply is divided by the voltage-dividing resistor circuit, and the voltage after the voltage division is connected to the "-" end of the operational amplifier circuit; the output of the amplifier circuit is divided by the voltage-dividing resistor circuit, and the voltage after the voltage division is connected to the sampling end of the switching power supply; the output size of the digital-to-analog conversion circuit is controlled by the microcontroller circuit, so as to adjust the size of the sampling signal of the switching power supply, and then adjust the size of the output voltage of the switching power supply. Under the condition of constant resistance, the purpose of adjusting the power of the heating resistor is achieved by adjusting the output voltage, so as to realize the adjustment of the heating power by the microcontroller circuit, and the opening and closing of the adjustment of the power of the heating resistor is realized through the enabling function of the switching power supply. The solution of the utility model avoids the demand for large transient power, is relatively mild in terms of power supply, can reduce the frequency of use of switching devices, increase the service life of the circuit, reduce the interference of electromagnetic compatibility, improve the reliability and stability of the circuit, has the characteristics of low cost and simple control, has a good improvement effect on some applications, and can be widely used. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the implementation of the utility model or the technical solution in the prior art, the following is a brief introduction to the drawings required for the implementation or the prior art description. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0024] Figure 1 The figure is a schematic diagram of the circuit structure of an embodiment of the utility model. DETAILED DESCRIPTION

[0025] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] like Figure 1 As shown, the utility model discloses a circuit structure for controlling heating power, specifically:

[0027] The microcontroller circuit U4 is connected to the input end of the digital-to-analog conversion circuit U3, the output end of the digital-to-analog conversion circuit U3 is connected to one end of a resistor R8, the other end of the resistor R8 is connected to the "+" end of the operational amplifier U2.1, the "-" end of the operational amplifier U2.1 and the output end of the operational amplifier U2.1 are both connected to one end of a resistor R4, the other end of the resistor R4 is connected to the "+" end of the operational amplifier U2.2, the "-" end of the operational amplifier U2.2 is connected to one end of a resistor R3 and a resistor R6, the other end of the resistor R3 is respectively connected to the other end of a resistor R5 and a resistor R7, the other end of the resistor R6 and the output end of the operational amplifier U2.2 are both connected to one end of a resistor R1, and the other end of the resistor R1 is connected One end of the resistor R2 is connected to the VSENSE pin of the switching power supply controller U1, the other end of the resistor R2 is grounded, the VIN pin of the switching power supply controller U1 is connected to the input voltage Vin, the ENA pin of the switching power supply controller U1 is connected to the enable signal Enable, the GND pin of the switching power supply controller U1 is grounded, the PH pin of the switching power supply controller U1 is connected to one end of the inductor L1 and the cathode of the Schottky diode D1, the anode of the Schottky diode D1 is connected to one end of the capacitor C1 and grounded, the other end of the capacitor C1 is connected to one end of the inductor L1, one end of the resistor R7, one end of the heating resistor and the output voltage Vout, the other end of the resistor R5 is grounded, and the other end of the heating resistor is grounded.

[0028] In this embodiment, the microcontroller circuit U4 adopts the model STM32F103VE, the digital analog conversion circuit U3 adopts the model DAC8830, and the switching power supply controller U1 adopts the model TPS5450.

[0029] The DC / DC switching power supply circuit composed of the switching power supply controller U1, inductor L1, Schottky diode D1 and capacitor C1 can adjust the output voltage through the sampling signal, and can control the opening and closing of the circuit through the enable signal, wherein the inductor L1, Schottky diode D1 and capacitor C1 form a power loop, and the DC / DC switching power supply circuit is used to provide a stable voltage output to the heating resistor, and realize the start and close of the switching power supply circuit under the action of the enable pin ENA and the enable signal Enable; the microcontroller circuit U4 drives the digital-to-analog conversion circuit U3 through the serial bus, and the digital-to-analog conversion circuit U3 receives the serial bus signal from the microcontroller circuit U4, and outputs different voltage signals, which are followed by the voltage through the operational amplifier U2.1. The circuit is transmitted to the "+" end of the operational amplifier U2.2, and the switching power supply output voltage divider resistor circuit composed of resistors R7 and R5 divides the output voltage of the switching power supply and transmits it to the "-" end of the operational amplifier U2.2; the operational amplifier U2.2, resistors R4, R3, and R6 form an operational amplifier circuit, which can process the input signal and output the required signal. After processing the input signals "+" and "-", the output voltage passes through the operational amplifier circuit output voltage divider resistor circuit composed of resistors R1 and R2, and is transmitted to the switching power supply controller U1. The switching power supply controller U1 adjusts the output according to the VESENSE signal to adjust the heating power of the heating resistor. The impedance of the heating resistor is fixed, and different heating powers can be output according to the applied voltage.

[0030] The output voltage of the digital-to-analog conversion circuit U3 is set to Vdac. After the voltage following by the operational amplifier U2.1, it is still Vdac. Therefore, the voltage at the “+” end of the operational amplifier U2.1 is Vdac.

[0031] The VSENSE signal of the switching power supply controller U1 is fixed and set to Vref.

[0032] After the voltage Vout passes through resistors R7 and R5, the voltage is

[0033] The output voltage of operational amplifier U2.2 is

[0034] The operational amplifier circuit composed of operational amplifier U2.2, resistor R3 and resistor R6 is a feedback circuit, and the transfer function is:

[0035]

[0036] Convert to:

[0037]

[0038] It can be seen from the above formula that when Vdac changes, Vout will be adjusted accordingly according to the formula, so as to achieve the purpose of adjusting the supply voltage of the heating resistor when controlling the digital-to-analog conversion circuit U3, and further achieve the purpose of adjusting the heating power.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

[0040] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A circuit structure for controlling heating power, characterized in that: include: A microcontroller circuit for outputting different control drive signals; A digital-to-analog conversion circuit, used for receiving a control drive signal from a microcontroller circuit and then outputting different voltage signals; A DC / DC switching power supply circuit with enable is used to output stable voltage and current, output adjustable voltage according to the sampling signal, and control the opening and closing of the circuit through the enable signal; The voltage-dividing resistor circuit at the output end of the switching power supply is used to divide the output voltage; The voltage follower circuit transmits the voltage of the digital-to-analog conversion circuit; An operational amplifier circuit is used to process an input signal and output a corresponding voltage signal; The voltage-dividing resistor circuit at the output end of the operational amplifier circuit is used to divide the output voltage of the operational amplifier circuit; Heating resistor, used to output different heating power when loaded with different voltages; The microcontroller circuit is connected to the input end of the digital-to-analog conversion circuit, the output end of the digital-to-analog conversion circuit is connected to the input end of the voltage follower circuit, the output end of the voltage follower circuit is respectively connected to the voltage-dividing resistor circuit at the output end of the switching power supply and the voltage-dividing resistor circuit at the output end of the operational amplifier circuit through the operational amplifier circuit, the enabled DC / DC switching power supply circuit is respectively connected to the voltage-dividing resistor circuit at the output end of the switching power supply, the voltage-dividing resistor circuit at the output end of the operational amplifier circuit, Vout and one end of the heating resistor, the voltage-dividing resistor circuit at the output end of the switching power supply is respectively connected to the enabled DC / DC switching power supply circuit, Vout and one end of the heating resistor, the Vout is connected to one end of the heating resistor, and the other end of the heating resistor is grounded.

2. A circuit structure for controlling heating power according to claim 1, characterized in that: The specific structure of the voltage follower circuit is: the output end of the digital-to-analog conversion circuit is connected to one end of the resistor R8, the other end of the resistor R8 is connected to the "+" end of the operational amplifier U2.1, and the "-" end of the operational amplifier U2.1 and the output end of the operational amplifier U2.1 are both connected to the operational amplifier circuit.

3. A circuit structure for controlling heating power according to claim 1, characterized in that: The specific structure of the operational amplifier circuit is as follows: the output end of the voltage follower circuit is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the "+" end of the operational amplifier U2.2, the "-" end of the operational amplifier U2.2 is respectively connected to one end of the resistor R3 and the resistor R6, the other end of the resistor R3 is connected to the voltage-dividing resistor circuit at the output end of the switching power supply, and the output end of the operational amplifier U2.2 and the other end of the resistor R6 are both connected to the voltage-dividing resistor circuit at the output end of the operational amplifier circuit.

4. A circuit structure for controlling heating power according to claim 3, characterized in that: The specific structure of the voltage-dividing resistor circuit at the output end of the operational amplifier circuit is as follows: the operational amplifier circuit is connected to one end of the resistor R1, the other end of the resistor R1 is respectively connected to the enabled DC / DC switching power supply circuit and one end of the resistor R2, and the other end of the resistor R2 is grounded.

5. A circuit structure for controlling heating power according to claim 3, characterized in that: The specific structure of the voltage divider resistor circuit at the output end of the switching power supply is: one end of the resistor R3 is respectively connected to one end of the resistor R5 and the resistor R7, the other end of the resistor R5 is grounded, and the other end of the resistor R7 is respectively connected to the enabled DC / DC switching power supply circuit, Vout and one end of the heating resistor.

6. A circuit structure for controlling heating power according to claim 1, characterized in that: The specific structure of the enabled DC / DC switching power supply circuit is as follows: the voltage-dividing resistor circuit at the output end of the operational amplifier circuit is connected to the VSENSE pin of the switching power supply controller U1, the enable pin ENA of the switching power supply controller U1 is connected to the enable signal Enable, the VIN pin of the switching power supply controller U1 is connected to the input voltage Vin, the GDN pin of the switching power supply controller U1 is grounded, the PH pin of the switching power supply controller U1 is respectively connected to one end of the inductor L1 and the negative electrode of the Schottky diode D1, the positive electrode of the Schottky diode D1 is connected to one end of the capacitor C1 and is grounded, the other end of the inductor L1 is respectively connected to the other end of the capacitor C1, the voltage-dividing resistor circuit at the output end of the switching power supply, one end of the heating resistor and Vout, and the model of the switching power supply controller U1 is TPS5450.

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