A synchronous control circuit based on a power frequency reference

Abstract

The utility model relates to electronic circuit technical field provides a synchronous control circuit based on power frequency reference, including main control unit and resistance -capacity voltage -reducing module, voltage conversion module and power frequency detection module, resistance -capacity voltage -reducing module input access alternating current input, and output end is connected with voltage conversion module, power frequency detection module input access alternating current input, and output end is connected with main control unit, and the power end of main control unit is connected with the output end of voltage conversion module, and its signal end is connected with power frequency detection module, design access alternating current input's power frequency detection module, detect the input frequency of alternating current input to the level signal feedback to main control unit to supply main control unit to carry out clock reference timing, and the clock reference of power frequency automatic calibration based on alternating current is simple in structure, low in cost, simultaneously configures the resistance -capacity voltage -reducing module, voltage conversion module of connection in proper order to carry out voltage conversion, and the output steady DC power supply has further reduced the manufacturing cost of circuit.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and in particular to a synchronous control circuit based on a power frequency reference. Background Technology

[0002] As the core of modern electronic systems, the reliable operation of a microcontroller unit (MCU) depends on two fundamental conditions: a stable power supply and an accurate clock signal. Current MCU clock circuits typically provide this clock signal through an internal clock or an external crystal oscillator circuit, as follows: Integrating an internal RC oscillator as a clock source has the advantages of low cost, no need for external components, and saving board space. The disadvantages are poor accuracy and temperature drift characteristics; the typical accuracy of an internal RC oscillator is usually between ±1% and ±5%, and its oscillation frequency will drift significantly with changes in ambient temperature and supply voltage.

[0003] Using an external quartz / ceramic crystal oscillator as a clock source offers the advantage of providing extremely high accuracy and stability up to ±10ppm (parts per million), effectively addressing the shortcomings of internal clock sources. The disadvantages include increased cost and circuit complexity, requiring at least one additional quartz crystal and two matching load capacitors, further increasing costs and hindering miniaturization design.

[0004] In summary, in existing microcontroller unit control circuits, using an internal clock results in a large error, while using an external clock increases manufacturing costs. Cost and accuracy are incompatible, which is detrimental to equipment control and manufacturing. Utility Model Content

[0005] This invention provides a synchronous control circuit based on a power frequency reference, which solves the technical problem that existing MCU control circuits cannot achieve both high precision and low cost.

[0006] To address the above technical problems, this utility model provides a synchronous control circuit based on a power frequency reference, comprising a main controller, a resistor-capacitor step-down module, a voltage conversion module, and a power frequency detection module; the input terminal of the resistor-capacitor step-down module is connected to an AC input, and its output terminal is connected to the voltage conversion module; the input terminal of the power frequency detection module is connected to an AC input, and its output terminal is connected to the main controller; the power supply terminal of the main controller is connected to the output terminal of the voltage conversion module, and its signal terminal is connected to the power frequency detection module; The AC power input is converted into DC power by the resistor-capacitor step-down module, and then DC-DC conversion is performed by the voltage conversion module to output a stable DC power supply to the main controller. The power frequency detection module detects the input frequency of the AC input and feeds it back to the main controller through a level signal for the main controller to perform reference timing.

[0007] This basic design incorporates an AC input power frequency detection module. By detecting the input frequency of the AC input and feeding it back to the main controller via a level signal, the main controller can use this signal for clock reference timing. The clock reference is automatically calibrated based on the AC power frequency, resulting in a simple structure and low cost. Simultaneously, a sequentially connected resistor-capacitor step-down module and a voltage conversion module are configured to perform voltage conversion, outputting a stable DC power supply. This eliminates the application cost of an LDO and further reduces the circuit manufacturing cost.

[0008] In a further embodiment, the power frequency detection module includes a first switch Q1, a diode D1, resistors R1, R2, and R3, and a capacitor C1. The base of the first switching transistor Q1 is connected to the AC input terminal ACN through resistor R1, the first terminal is connected to the AC input terminal ACL, and the second terminal is connected to the signal terminal of the main controller through resistor R2. The positive terminal of diode D1 is connected to the base of the first switching transistor Q1, and the negative terminal is connected to the AC input terminal ACL; one end of resistor R3 is connected to the signal terminal of the main controller, and the other end is grounded; capacitor C is connected in parallel with capacitor C1.

[0009] This solution uses the first switching transistor Q1 as its core. Because the switching speed of this transistor is extremely fast (microseconds or even nanoseconds), far exceeding the cycle of the power frequency signal (20ms), it can precisely complete the state transition at (or near) the zero-crossing point of the AC voltage, generating a square wave with a very steep edge. The main controller (e.g., an MCU) can capture this precise transition edge, thereby achieving high-precision measurement of the power frequency cycle and thus enabling a high-precision clock signal. Furthermore, the low cost of the components further reduces manufacturing costs, and it is compatible with miniaturized designs, has strong anti-interference capabilities, and high security, meeting the clock reference input requirements of most microcontrollers on the market.

[0010] In a further embodiment, the resistor-capacitor step-down module includes resistor R4, resistor R5, capacitor C2, capacitor C3, diode D2, and diode D3; one end of resistor R4 is connected to the AC input terminal ACN, and the other end is connected to the negative terminal of diode D3 through capacitor C2; the negative terminal of diode D2 is connected to the AC input terminal ACL and the voltage conversion module, and the negative terminal is connected between resistor R4 and diode D3; resistor R5 is connected in parallel with capacitor C2, the positive terminal of capacitor C3 is connected to the AC input terminal ACL, and the negative terminal is connected to the positive terminal of diode D3.

[0011] This design incorporates resistors R4 and R5, capacitors C2 and C3, and diodes D2 and D3 to construct a resistor-capacitor step-down module. Based on a full-wave rectifier bridge, it converts AC power to DC power, resulting in high power efficiency. Furthermore, it utilizes common and inexpensive electronic components, significantly reducing equipment costs. The fewer components also reduce PCB board area, further enabling product miniaturization.

[0012] In a further embodiment, the voltage conversion module includes a voltage regulator module and a switching buck module. The input terminal of the voltage regulator module is connected to the output terminal of the resistor-capacitor buck module, and the output terminal is connected to the input terminal of the switching buck module. The output terminal of the switching buck module is connected to the power supply terminal of the main controller. The AC power input to the resistor-capacitor step-down module is converted into DC power. After rectification by the voltage regulator module, it is input to the switching step-down module, where it is stepped down and then output as a stable DC power supply to the main controller.

[0013] In a further embodiment, the voltage regulator module includes a Zener diode ZD1 and a Zener diode ZD2; the positive terminal of Zener diode ZD1 is connected to the control terminal of the switching buck module, and the negative terminal is connected to the output terminal of the resistor-capacitor buck module; the positive terminal of Zener diode ZD2 is connected to the input terminal of the switching buck module, and the negative terminal is connected to the control terminal of the switching buck module.

[0014] This solution inserts a voltage regulator module consisting of Zener diodes ZD1 and ZD2 between the voltage regulator module and the switching buck module, providing a fast and reliable "voltage clamp" for the subsequent circuits. This effectively defends against abnormal events such as overvoltage, voltage spikes, surges, and ESD, significantly improving the stability and reliability of the system.

[0015] In a further embodiment, the control terminal of the switching buck module includes a second switching transistor Q2, a resistor R6, a capacitor C4, and a capacitor C5. The base of the second switching transistor Q2 is connected to the positive terminal of the Zener diode ZD1 as the control terminal, with its first terminal grounded and its second terminal connected to the positive terminal of the Zener diode ZD2 as the input terminal. The two ends of the resistor R6 are connected to the base and the second terminal of the second switching transistor Q2, respectively. The positive terminal of the capacitor C4 is connected to the negative terminal of the Zener diode ZD1, and its other end is grounded. The capacitor C5 is connected in parallel with the capacitor C4.

[0016] This solution uses a series connection of transistors to reduce the voltage by adjusting the voltage divider of the switching transistors, resulting in low cost and stable output voltage.

[0017] In a further implementation, a protection module is also included, wherein the input terminal of the protection module is connected to an AC input, and the output terminal is connected to the resistor-capacitor step-down module and the power frequency detection module.

[0018] In a further embodiment, the protection module includes resistors R7 and R8; one end of resistor R7 is connected to the AC input terminal ACL, and the other end is connected between resistors R4 and R5 through resistor R8.

[0019] This solution incorporates series resistors R7 and R8 at the AC input terminal for current limiting and overcurrent protection, thereby improving circuit stability.

[0020] In a further embodiment, the protection module further includes a capacitor C6 and a varistor VR1; one end of the varistor VR1 is connected to the AC input terminal ACL, and the other end is connected to the AC input terminal ACN; the capacitor C6 and the varistor VR1 are connected in parallel.

[0021] This solution uses a parallel capacitor C6 and a varistor VR1 to absorb huge surge currents instantly, clamping the voltage within a safe range and thus protecting subsequent circuits. Attached Figure Description

[0022] Figure 1 This is a system framework diagram of a synchronization control circuit based on a power frequency reference provided in an embodiment of this utility model; Figure 2 This is provided by the embodiment of the present utility model. Figure 1 Partial hardware circuit diagram; Figure 3 This is provided by the embodiment of the present utility model. Figure 1 Partial hardware circuit diagram; The system consists of: main controller 1, resistor-capacitor step-down module 2, voltage conversion module 3, power frequency detection module 4, and protection module 5. Detailed Implementation

[0023] The embodiments of this utility model are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the utility model. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of this utility model, because many changes can be made to this utility model without departing from the spirit and scope of this utility model.

[0024] This utility model provides a synchronization control circuit based on a power frequency reference, such as... Figure 1 , Figure 2 , Figure 3As shown, in this embodiment, it includes a main controller 1, a resistor-capacitor step-down module 2, a voltage conversion module 3, and a power frequency detection module 4; the input terminal of the resistor-capacitor step-down module 2 is connected to the AC input, and its output terminal is connected to the voltage conversion module 3; the input terminal of the power frequency detection module 4 is connected to the AC input, and its output terminal is connected to the main controller 1; the power supply terminal of the main controller 1 is connected to the output terminal of the voltage conversion module 3, and its signal terminal is connected to the power frequency detection module 4. The AC power input is converted into DC power by the resistor-capacitor step-down module 2, and then DC-DC conversion is performed by the voltage conversion module 3 to output a stable DC power supply to the main controller 1. The power frequency detection module 4 detects the input frequency of the AC input and feeds it back to the main controller 1 through a level signal so that the main controller 1 can perform reference timing.

[0025] Among them, the main controller 1 includes, but is not limited to, an MCU.

[0026] In this embodiment, the power frequency detection module 4 includes a first switch Q1, a diode D1, resistors R1, R2, and R3, and a capacitor C1; The base of the first switching transistor Q1 is connected to the AC input terminal ACN through resistor R1, the first terminal is connected to the AC input terminal ACL, and the second terminal is connected to the signal terminal of the main controller 1 through resistor R2. The positive terminal of diode D1 is connected to the base of the first switching transistor Q1, and the negative terminal is connected to the AC input terminal ACL; one end of resistor R3 is connected to the signal terminal of the main controller 1, and the other end is grounded; capacitor C is connected in parallel with capacitor C1.

[0027] In this embodiment, the first switching transistor Q1 is preferably an NPN transistor, with its first terminal being the emitter and its second terminal being the collector. In other embodiments, a PNP transistor may also be selected as required.

[0028] This embodiment uses the first switching transistor Q1 as the core. Because the switching speed of the transistor is very fast (microseconds or even nanoseconds), much faster than the period of the power frequency signal (20ms), it can very accurately complete the state transition at the instant (or near) the zero-crossing point of the AC voltage, generating a square wave with a very steep edge. The main controller 1 (e.g., MCU) can capture this precise transition edge, thereby achieving high-precision measurement of the power frequency period and thus enabling a high-precision clock signal. At the same time, the low cost of components further reduces manufacturing costs, and it is suitable for miniaturized settings, has strong anti-interference capabilities, and high security, and can meet the clock reference access requirements of most microcontrollers on the market.

[0029] In this embodiment, the resistor-capacitor step-down module 2 includes resistor R4, resistor R5, capacitor C2, capacitor C3, diode D2, and diode D3; one end of resistor R4 is connected to the AC input terminal ACN, and the other end is connected to the negative terminal of diode D3 through capacitor C2; the negative terminal of diode D2 is connected to the AC input terminal ACL and voltage conversion module 3, and the negative terminal is connected between resistor R4 and diode D3; resistor R5 is connected in parallel with capacitor C2, the positive terminal of capacitor C3 is connected to the AC input terminal ACL, and the negative terminal is connected to the positive terminal of diode D3.

[0030] In this embodiment, resistors R4 and R5, capacitors C2 and C3, diodes D2 and D3 are used to construct a resistor-capacitor step-down module 2. Based on a full-wave rectifier bridge, AC power is converted into DC power, resulting in high power efficiency. Furthermore, the use of common and inexpensive electronic components significantly reduces the cost of the equipment. The small number of components reduces the PCB board area occupied, further realizing product miniaturization.

[0031] In this embodiment, the voltage conversion module 3 includes a voltage regulator module and a switching buck module. The input terminal of the voltage regulator module is connected to the output terminal of the resistor-capacitor buck module 2, and the output terminal is connected to the input terminal of the switching buck module. The output terminal of the switching buck module is connected to the power supply terminal of the main controller 1. After the AC power is input to the resistor-capacitor step-down module 2, it is converted into DC power. After being rectified by the voltage regulator module, it is input to the switch step-down module. After being stepped down, a stable DC power is output to the main controller 1.

[0032] In this embodiment, the voltage regulator module includes a Zener diode ZD1 and a Zener diode ZD2; the positive terminal of Zener diode ZD1 is connected to the control terminal of the switching buck module, and the negative terminal is connected to the output terminal of the RC buck module 2; the positive terminal of Zener diode ZD2 is connected to the input terminal of the switching buck module, and the negative terminal is connected to the control terminal of the switching buck module.

[0033] In this embodiment, a voltage regulator module consisting of Zener diodes ZD1 and ZD2 is inserted between the voltage regulator module and the switching buck module. This provides a fast and reliable "voltage clamp" for the subsequent circuits, effectively preventing abnormal events such as overvoltage, voltage spikes, surges, and ESD, and significantly improving the stability and reliability of the system.

[0034] In this embodiment, the control terminal of the switching buck module includes a second switching transistor Q2, a resistor R6, a capacitor C4, and a capacitor C5. The base of the second switching transistor Q2 is connected to the positive terminal of the Zener diode ZD1 as the control terminal, with its first terminal grounded and its second terminal connected to the positive terminal of the Zener diode ZD2 as the input terminal. The two ends of the resistor R6 are connected to the base and the second terminal of the second switching transistor Q2, respectively. The positive terminal of the capacitor C4 is connected to the negative terminal of the Zener diode ZD1, and its other end is grounded. The capacitor C5 is connected in parallel with the capacitor C4.

[0035] In this embodiment, the second switching transistor Q2 is preferably an NPN transistor, with its first terminal being the emitter and its second terminal being the collector. In other embodiments, a PNP transistor may also be selected as needed.

[0036] This embodiment uses a series connection of transistors to reduce the voltage by adjusting the voltage divider of the switching transistors, which is low-cost and provides a stable output voltage.

[0037] In this embodiment, a protection module 5 is also included. The input terminal of the protection module 5 is connected to the AC input, and the output terminal is connected to the resistor-capacitor step-down module 2 and the power frequency detection module 4.

[0038] In this embodiment, the protection module 5 includes resistor R7 and resistor R8; one end of resistor R7 is connected to the AC input terminal ACL, and the other end is connected between resistor R4 and resistor R5 through resistor R8.

[0039] In this embodiment, series resistors R7 and R8 are set at the AC input terminal to perform current limiting and overcurrent protection, thereby improving circuit stability.

[0040] In this embodiment, the protection module 5 further includes a capacitor C6 and a varistor VR1; one end of the varistor VR1 is connected to the AC input terminal ACL, and the other end is connected to the AC input terminal ACN; the capacitor C6 and the varistor VR1 are connected in parallel.

[0041] In this embodiment, a capacitor C6 and a varistor VR1 are connected in parallel to absorb a huge surge current instantly, clamping the voltage within a safe range and thus protecting the subsequent circuits.

[0042] Taking the main controller 1 as an MCU as an example, the working principle of this embodiment is as follows: (1) Power output The AC input power is converted into DC power by the resistor-capacitor step-down module 2, and then output as approximately 12V DC power through the voltage regulator module.

[0043] Since the emitter voltage of the second switching transistor Q2 follows the base voltage, and the base voltage is clamped at 5.6V, the emitter voltage of the second switching transistor Q2 relative to the reference potential GND is 6.3V, because the emitter voltage of the second switching transistor Q2 is approximately 0.7V. Since the voltage across Zener diodes ZD2 and ZD3 is 11.2V (approximately 12V), the collector-emitter voltage of the second switching transistor Q2 is the previously known 6.3V (5.6 + 0.7).

[0044] We can determine that the voltage across C12 is 11.2 - 6.3 = 4.9V, meaning the output voltage of VCC is approximately 4.9V. This means the 12V is stepped down to 5V as the power supply VCC output to power the main controller 1 or other devices. Figure 2 The resistor R9 represents the output dummy load.

[0045] (2) Clock reference adjustment The alternating positive and negative half-cycles of the AC power supply are as follows: during the positive half-cycle, the first switching transistor Q1 is turned on and outputs a high level; during the negative half-cycle, the first switching transistor Q1 is turned off and outputs a low level. The MCU's (microcontroller) I / O port PB0 (signal terminal) generates a square wave with high and low transitions at a frequency of 50Hz, which is the power frequency. In this way, the MCU can use this fixed frequency as a clock reference to control the start and stop times of relays, motors, etc.

[0046] like Figure 3 The MCU controls the start and stop of motor MG1 through a switching control circuit composed of transistors.

[0047] This utility model embodiment designs a power frequency detection module 4 that connects to the AC input. By detecting the input frequency of the AC input, the module feeds back the level signal to the main controller 1 for clock reference timing. The clock reference is automatically calibrated based on the AC power frequency, which is simple in structure and low in cost. At the same time, a resistor-capacitor step-down module 2 and a voltage conversion module 3 are configured in sequence to perform voltage conversion and output a stable DC power supply, eliminating the application cost of LDO and further reducing the manufacturing cost of the circuit.

[0048] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A synchronous control circuit based on a power frequency reference, characterized in that: It includes a main controller, a resistor-capacitor step-down module, a voltage conversion module, and a power frequency detection module; the input terminal of the resistor-capacitor step-down module is connected to an AC input, and its output terminal is connected to the voltage conversion module; the input terminal of the power frequency detection module is connected to an AC input, and its output terminal is connected to the main controller; the power supply terminal of the main controller is connected to the output terminal of the voltage conversion module, and its signal terminal is connected to the power frequency detection module. The AC power input is converted into DC power by the resistor-capacitor step-down module, and then DC-DC conversion is performed by the voltage conversion module to output a stable DC power supply to the main controller. The power frequency detection module detects the input frequency of the AC input and feeds it back to the main controller through a level signal for the main controller to perform reference timing.

2. The synchronous control circuit based on a power frequency reference as described in claim 1, characterized in that: The power frequency detection module includes a first switch Q1, a diode D1, resistors R1, R2, and R3, and a capacitor C1. The base of the first switching transistor Q1 is connected to the AC input terminal ACN through resistor R1, the first terminal is connected to the AC input terminal ACL, and the second terminal is connected to the signal terminal of the main controller through resistor R2. The positive terminal of diode D1 is connected to the base of the first switching transistor Q1, and the negative terminal is connected to the AC input terminal ACL; one end of resistor R3 is connected to the signal terminal of the main controller, and the other end is grounded; capacitor C is connected in parallel with capacitor C1.

3. The synchronous control circuit based on a power frequency reference as described in claim 2, characterized in that: The resistor-capacitor step-down module includes resistor R4, resistor R5, capacitor C2, capacitor C3, diode D2, and diode D3. One end of resistor R4 is connected to the AC input terminal ACN, and the other end is connected to the negative terminal of diode D3 through capacitor C2. The negative terminal of diode D2 is connected to the AC input terminal ACL and the voltage conversion module, and the negative terminal is connected between resistor R4 and diode D3. Resistor R5 is connected in parallel with capacitor C2. The positive terminal of capacitor C3 is connected to the AC input terminal ACL, and the negative terminal is connected to the positive terminal of diode D3.

4. The synchronous control circuit based on a power frequency reference as described in claim 3, characterized in that: The voltage conversion module includes a voltage regulator module and a switching buck module. The input terminal of the voltage regulator module is connected to the output terminal of the resistor-capacitor buck module, and the output terminal is connected to the input terminal of the switching buck module. The output terminal of the switching buck module is connected to the power supply terminal of the main controller. The AC power input to the resistor-capacitor step-down module is converted into DC power. After rectification by the voltage regulator module, it is input to the switching step-down module, where it is stepped down and then output as a stable DC power supply to the main controller.

5. The synchronous control circuit based on a power frequency reference as described in claim 4, characterized in that: The voltage regulator module includes a Zener diode ZD1 and a Zener diode ZD2; the positive terminal of Zener diode ZD1 is connected to the control terminal of the switching buck module, and the negative terminal is connected to the output terminal of the resistor-capacitor buck module; the positive terminal of Zener diode ZD2 is connected to the input terminal of the switching buck module, and the negative terminal is connected to the control terminal of the switching buck module.

6. The synchronous control circuit based on a power frequency reference as described in claim 5, characterized in that: The control terminal connection of the switching buck module includes a second switching transistor Q2, a resistor R6, a capacitor C4, and a capacitor C5. The base of the second switching transistor Q2 is connected to the positive terminal of the Zener diode ZD1 as the control terminal, the first terminal is grounded, and the second terminal is connected to the positive terminal of the Zener diode ZD2 as the input terminal. The two ends of the resistor R6 are connected to the base and the second terminal of the second switching transistor Q2, respectively. The positive terminal of the capacitor C4 is connected to the negative terminal of the Zener diode ZD1, and the other end is grounded. The capacitor C5 is connected in parallel with the capacitor C4.

7. The synchronous control circuit based on a power frequency reference as described in claim 3, characterized in that: It also includes a protection module, whose input terminal is connected to an AC input and whose output terminal is connected to the resistor-capacitor step-down module and the power frequency detection module.

8. The synchronous control circuit based on a power frequency reference as described in claim 7, characterized in that: The protection module includes resistors R7 and R8; one end of resistor R7 is connected to the AC input terminal ACL, and the other end is connected between resistors R4 and R5 through resistor R8.

9. A synchronization control circuit based on a power frequency reference as described in claim 8, characterized in that: The protection module also includes a capacitor C6 and a varistor VR1; one end of the varistor VR1 is connected to the AC input terminal ACL, and the other end is connected to the AC input terminal ACN; the capacitor C6 and the varistor VR1 are connected in parallel.

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