一种高精度灯丝电源电路

Abstract

本实用新型涉及一种高精度灯丝电源电路，包括：ACDC模块、半桥电路、BUCK电路和采样电路；ACDC模块将输入的标准交流电压转换为低纹波的直流电压；半桥电路将直流电压转换为高频交流电压后输入BUCK电路；BUCK电路将高频交流电压降低后输出至外部的负载灯丝；采样电路包括：电阻R1、电阻R2和放大器；电阻R1和电阻R2串联后两端分别与BUCK电路的输出端连接；放大器与电阻R2并联测量电阻R2两端的分压，得到BUCK电路的输出电压；通过设置采样电路能准确获取灯丝电流实际值，进而能根据该电流实际值对灯丝电源进行精准控制。

Claims

1. A high-precision filament power supply circuit, characterized in that, The filament power supply circuit includes: an AC / DC module, a half-bridge circuit, a BUCK circuit, and a sampling circuit; The ACDC module converts the input standard AC voltage into a low-ripple DC voltage; The half-bridge circuit converts the DC voltage into a high-frequency AC voltage, which is then input into the BUCK circuit. The BUCK circuit reduces the high-frequency AC voltage and outputs it to the external load filament. The sampling circuit includes: resistor R1, resistor R2, and amplifier; The resistors R1 and R2 are connected in series, and their two ends are respectively connected to the output terminal of the BUCK circuit. The amplifier is connected in parallel with the resistor R2 to measure the voltage drop across the resistor R2, thereby obtaining the output voltage of the BUCK circuit.

2. The filament power supply circuit of claim 1, wherein The half-bridge circuit includes: a half-bridge series resonant circuit; The half-bridge series resonant circuit includes: resistor R5, resistor R6, capacitor C1, capacitor C2, NMOS transistor M1, NMOS transistor M2, and resonant inductor Lr1; The two ends of the series connection of resistors R5 and R6 are respectively connected to the two ends of the output terminal of the ACDC module. The two ends of the series connection between capacitor C1 and capacitor C2 are respectively connected to the two ends of the output terminal of the ACDC module; The two ends of the connection between the drain (D) of NMOS transistor M1 and the source (S) of NMOS transistor M2 are respectively connected to the two ends of the output terminal of the ACDC module. One end of the resonant inductor Lr1 is connected to the connection point of resistors R5 and R6 and the connection point of capacitors C1 and C2, and the other end serves as an output terminal of the half-bridge series resonant circuit. The connection point of NMOS transistors M1 and M2 serves as the other output terminal of the half-bridge series resonant circuit.

3. The filament power supply circuit of claim 2, wherein, The half-bridge circuit includes: transformer Tr1; The low-voltage side of the transformer Tr1 is connected to the output terminal of the half-bridge series resonant circuit.

4. The filament power supply circuit of claim 3, wherein The half-bridge circuit includes: a high-frequency rectifier circuit; the input terminal of the high-frequency rectifier circuit is connected to the high-voltage side of the transformer Tr1, and the output terminal is connected to the BUCK circuit. The high-frequency rectifier circuit includes: a full-bridge circuit composed of diodes D1, D2, D3, and D4, and a capacitor C3 connected in parallel with the full-bridge circuit.

5. The filament power supply circuit of claim 1, wherein, The BUCK circuit includes: NMOS transistor M3, NMOS transistor M4, inductor L1 and capacitor C2; The drain (D) of the NMOS transistor M3 is connected to one end of the output of the half-bridge circuit, and the source (S) is connected to one end of the inductor L1 and the source (S) of the NMOS transistor M4; the other end of the inductor L1 is connected to one end of the capacitor C2, and the other end of the capacitor is connected to the drain (D) of the NMOS transistor M4. The two ends of the capacitor C2 are connected to the external load filament as the output of the BUCK circuit.

6. The filament power supply circuit of claim 5, wherein, The filament power supply circuit further includes a control circuit connected to the gate of the NMOS transistors M3 and M4; the control circuit sends a voltage signal to adjust the duty cycle of the NMOS transistors M3 and M4, thereby adjusting the output voltage of the BUCK circuit.

7. The filament power supply circuit of claim 6, wherein, The control circuit includes: an optical fiber, a comparator, and a PI regulator; One input of the comparator receives an externally transmitted analog signal Iref through the optical fiber, and the other input of the comparator is connected to the output of the sampling circuit. The comparator sends the comparison result of the analog signal Iref with the output voltage of the BUCK circuit measured by the sampling circuit to the PI regulator, and the PI regulator outputs a control signal to the NMOS transistor M3 and the NMOS transistor M4.

8. The filament power supply circuit of claim 1, wherein, The amplifier is an instrumentation amplifier; a resistor R3 is connected between the positive and negative input terminals of the instrumentation amplifier, and a resistor R4 is connected to the output terminal.

9. The filament power supply circuit of claim 8, wherein, The resistors R1, R2, R3, and R4 are resistors with a temperature drift rating of 15 ppm / ℃.

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