Low-ripple and low-harmonic power supply charger

Abstract

The utility model discloses a low-ripple and low-harmonic power supply charger. The internal circuit comprises a commercial power input and over-current protection circuit, an EMI filtering electromagnetic anti-interference circuit, a harmonic improvement circuit, a rectification filter circuit, a PWM control IC and MOSFET tube driving circuit, a high-frequency transformer conversion circuit, an output rectification filter circuit, an MCU protection and charging control circuit, a loop control circuit, a load short circuit prevention and reverse insertion circuit and an output low ripple and EMI circuit. According to the lead-acid battery power supply charger of the utility model, the EMI filtering electromagnetic anti-interference circuit, the harmonic improvement circuit, the output rectification filter circuit and the output low ripple and EMI circuit are designed, and the high-frequency transformer is adopted, so that the power supply charger is provided with a multi-stage ripple and harmonic suppression circuit, and therefore, ripple and harmonic generated in the charger can be improved and suppressed; working stability and power supply efficiency of the power supply charger are ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of power chargers, and in particular relates to a low ripple and low harmonic power charger. Background Art

[0002] The power charger is generally composed of a pulse width modulation PWM control IC and a MOSFET, which controls the switching time ratio to maintain a stable output voltage. Due to the reduction in the number of turns of the iron ring and the volume of the iron core, as well as its small size, ripples and harmonics are easily generated, and ripples may cause various hazards to the circuit, and are extremely fatal to the circuit. Once ripples are generated, they are easy to cause harmonics, which harm the circuit itself while reducing the power efficiency. Higher ripples will cause surges and directly damage the circuit. Even if the circuit is not directly destroyed, it will greatly interfere with the logical relationship of the digital circuit and affect the operation. The output ripple of the power charger mainly comes from the residual low-frequency ripple of the output, the high-frequency ripple with the same high frequency as the switch operation, the common-mode ripple noise caused by parasitics, the ultra-high frequency resonance noise of the power device switch, and the ripple noise caused by closed-loop regulation control. Therefore, it is necessary to suppress and improve the ripple and harmonics inside the power charger. Utility Model Content

[0003] The utility model aims to solve the above problems and provide a low ripple and low harmonic power charger, by adding a ripple and harmonic suppression circuit to the internal circuit of the charger, thereby improving and suppressing the ripple and harmonics generated inside the charger and ensuring the working stability and power efficiency of the power charger.

[0004] The utility model is realized by the following technical solutions:

[0005] A low ripple and low harmonic power charger, whose internal circuit includes a mains input and overcurrent protection circuit, an EMI filter electromagnetic anti-interference circuit, a harmonic improvement circuit, a rectifier filter circuit, a PWM control IC and a MOSFET tube drive circuit, a high-frequency transformer conversion circuit, an output rectifier filter circuit, an MCU protection and charging control circuit, a loop control circuit, a load short circuit and reverse insertion protection circuit, and an output low ripple and EMI circuit;

[0006] The mains input and overcurrent protection circuit is connected to the harmonic improvement circuit through the EMI filter electromagnetic anti-interference circuit, the EMI filter electromagnetic anti-interference circuit is provided with a filter inductor NF1, the neutral line of the harmonic improvement circuit is connected in series with a common mode inductor L1, and the neutral line and the live line of the harmonic improvement circuit are connected to the filter inductor NF2; the AC output end of the harmonic improvement circuit is connected to the input end of the rectifier bridge BD1 of the rectifier and filter circuit, and a parallel circuit composed of filter capacitors C1 and C2 is connected between the DC output ends of the rectifier bridge BD1, and the positive pole of the output end of the rectifier bridge BD1 of the rectifier and filter circuit is connected to the high-frequency transformer of the high-frequency transformer conversion circuit. The positive terminal of the primary first winding of T1 and the negative terminal of the primary first winding are connected to the PWM control IC and MOSFET tube drive circuit containing MOS tube Q1, the negative terminal of the primary first winding is connected to the drain of MOS tube Q1, and the source of MOS tube Q1 is connected to PGND through resistor R7; the gate of the MOS tube Q1 is connected to the PWM control IC chip U1 of the PWM control IC and MOSFET tube drive circuit; the two ends of the secondary first winding of the high-frequency transformer T1 are connected to the output rectifier filter circuit, and a diode D10 is connected in series on the positive line of the output rectifier filter circuit, and the two ends of the diode D10 are connected to a number of resistors and capacitor C1 4 is connected in parallel, and a parallel circuit composed of a capacitor C5, a resistor R37, a resistor R38, a resistor R39, and a resistor R40 is connected between the positive and negative lines of the output rectifier and filter circuit; the positive output end of the output rectifier and filter circuit is output to the positive output end of the charger after passing through one inductor coil in the common mode inductor NF3 of the output low ripple and EMI circuit 11; the negative electrode of the output rectifier and filter circuit is connected to GND, and the negative electrode of the output rectifier and filter circuit is connected to the negative line of the anti-load short circuit and reverse plug-in circuit, and the anti-load short circuit and reverse plug-in circuit includes a thyristor Q2 for preventing current backflow, and a triode Q7 for preventing load short circuit; The control electrode of the thyristor Q2 is connected to the control output terminal DRIVER1 of the intelligent control chip U2 of the MCU protection and charging control circuit through a resistor R60, and the model of the chip U2 is simHT45F5Q; the negative line of the load short circuit protection and reverse plug-in protection circuit is output to the negative output terminal of the charger after passing through another inductor coil in the common mode inductor NF3; the intelligent control chip U2 of the MCU protection and charging control circuit is connected to the input terminal of the optocoupler U3 in the loop control circuit, and the output terminal of the optocoupler U3 is connected to the feedback input terminal of the PWM control IC chip U1 of the PWM control IC and MOSFET tube drive circuit.

[0007] Furthermore, an overcurrent protection fuse F1 is provided in the mains input and overcurrent protection circuit.

[0008] Furthermore, the model of the high-frequency transformer T1 is PQ3225.

[0009] Furthermore, the PWM control IC chip U1 of the PWM control IC and MOSFET tube drive circuit is RM6500S.

[0010] Furthermore, the model of the optocoupler U3 in the loop control circuit is EL817.

[0011] Furthermore, the chip U2 of the MCU protection and charging control circuit is also connected to a power device or an ambient temperature over-temperature protection and detection circuit, and the over-temperature protection and detection circuit includes thermistors RT2 and RT3, and the detection signal ends derived from the thermistors RT2 and RT3 are respectively connected to the detection input pins of the chip U2.

[0012] Furthermore, the loop control circuit is also connected to an LED charging indicator LED1, and the LED1 is a dual-way indicator light, which is respectively connected to the output control pins of the chip U2.

[0013] The beneficial effects of the utility model are as follows: the low ripple and low harmonic power charger of the utility model is designed with an EMI filtering electromagnetic anti-interference circuit, a harmonic improvement circuit, an output rectifier filtering circuit and an output low ripple and EMI circuit, and adopts a high-frequency transformer, so that the power charger has a multi-stage ripple and harmonic suppression circuit, thereby improving and suppressing the ripple and harmonics generated inside the charger, and ensuring the working stability and power efficiency of the power charger. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a principle block diagram of the utility model.

[0015] Figure 2 This is a circuit schematic diagram of the utility model.

[0016] In the figure, 1. AC input and overcurrent protection circuit, 2. EMI filtering electromagnetic anti-interference circuit, 3. Harmonic improvement circuit, 4. Rectification and filtering circuit, 5. PWM control IC and MOSFET tube drive circuit, 6. High-frequency transformer conversion circuit, 7. Output rectification and filtering circuit, 8. MCU protection and charging control circuit, 9. Loop control circuit, 10. Anti-load short circuit and reverse insertion circuit, 11. Output low ripple and EMI circuit. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with specific examples and accompanying drawings.

[0018] like Figure 1 , Figure 2As shown, a low ripple and low harmonic power charger, whose internal circuit includes a mains input and overcurrent protection circuit 1, an EMI filtering electromagnetic anti-interference circuit 2, a harmonic improvement circuit 3, a rectifier filter circuit 4, a PWM control IC and MOSFET tube drive circuit 5, a high-frequency transformer conversion circuit 6, an output rectifier filter circuit 7, an MCU protection and charging control circuit 8, a loop control circuit 9, an anti-load short circuit and reverse insertion circuit 10 and an output low ripple and EMI circuit 11.

[0019] The mains input and overcurrent protection circuit 1 is provided with an overcurrent protection fuse F1.

[0020] The mains input and overcurrent protection circuit 1 is connected to the harmonic improvement circuit 3 through the EMI filtering electromagnetic anti-interference circuit 2. The EMI filtering electromagnetic anti-interference circuit 2 is provided with a filter inductor NF1. The neutral line of the harmonic improvement circuit 3 is connected in series with a common mode inductor L1, and the model of L1 is EE25. The neutral line and the live line of the harmonic improvement circuit 3 are then connected to the filter inductor NF2, and the model of the filter inductor NF2 is T1212; the AC output end of the harmonic improvement circuit 3 is then connected to the input end of the rectifier bridge BD1 of the rectifier and filter circuit 4, and a parallel circuit composed of filter capacitors C1 and C2 is connected between the DC output ends of the rectifier bridge BD1. The DC output ends of the rectifier and filter circuit 4 The positive pole of the output end of the rectifier bridge BD1 is connected to the positive pole of the primary first winding of the high-frequency transformer T1 of the high-frequency transformer conversion circuit 6. The model of the high-frequency transformer T1 is PQ3225. The negative pole of the primary first winding is connected to the PWM control IC and MOSFET tube drive circuit 5 containing the MOS tube Q1. The negative pole of the primary first winding is connected to the drain of the MOS tube Q1. The source of the MOS tube Q1 is connected to PGND through a resistor R7. The gate of the MOS tube Q1 is connected to the PWM control IC chip U1 of the PWM control IC and the MOSFET tube drive circuit 5. The model of the chip U1 is RM6500S. The secondary first winding of the high-frequency transformer T1 is connected to the PWM control IC and the MOSFET tube drive circuit 5. Both ends of the winding are connected to the output rectifier and filter circuit 7, a diode D10 is connected in series on the positive line of the output rectifier and filter circuit 7, both ends of the diode D10 are connected in parallel with a resistor matrix composed of resistors R29, R30, R31, R32, R33, R34, R35, and R36 and a series circuit composed of a capacitor C14, and a parallel circuit composed of a capacitor C5, a resistor R37, a resistor R38, a resistor R39, and a resistor R40 is connected between the positive and negative lines of the output rectifier and filter circuit 7; the positive output end of the output rectifier and filter circuit 7 is output to the positive output end of the charger after passing through an inductor coil in the common mode inductor NF3 of the output low ripple and EMI circuit 11. ; The negative electrode of the output rectifier filter circuit 7 is connected to GND, and the negative electrode of the output rectifier filter circuit 7 is connected to the negative electrode line of the anti-load short circuit and reverse plug-in circuit 10, and the anti-load short circuit and reverse plug-in circuit 10 includes a thyristor Q2 for preventing current backflow, and a triode Q7 for preventing load short circuit; The control electrode of the thyristor Q2 is connected to the control output terminal DRIVER1 of the intelligent control chip U2 of the MCU protection and charging control circuit 8 through a resistor R60, and the model of the chip U2 is simHT45F5Q; The negative electrode line of the anti-load short circuit and reverse plug-in circuit 10 is output to the negative output terminal of the charger after passing through another inductor coil in the common mode inductor NF3;The intelligent control chip U2 of the MCU protection and charging control circuit 8 is connected to the input end of the optocoupler U3 in the loop control circuit 9, and the output end of the optocoupler U3 is connected to the feedback input end of the PWM control IC chip U1 of the PWM control IC and MOSFET tube drive circuit 5. The model of the optocoupler U3 is EL817.

[0021] The chip U2 of the MCU protection and charging control circuit 8 is also connected to a power device or ambient temperature over-temperature protection and detection circuit. The over-temperature protection and detection circuit includes thermistors RT2 and RT3. The detection signal ends derived from thermistors RT2 and RT3 are respectively connected to the detection input pins of the chip U2: PA7 input pin and OPAOUT input pin.

[0022] The loop control circuit 9 is also connected to the LED charging indicator LED1. The LED1 is a dual-path indicator light, which is respectively connected to the output control pins of the chip U2: one LED1-A is connected to the PA6 pin of the chip U2, and the other LED1-B is connected to the PA5 pin of the chip U2.

[0023] A series of Y capacitors, YC1 and YC2, are connected between the PGND and the GND.

[0024] The above embodiments are only preferred implementation modes of the present invention and are only used to explain the present invention rather than to limit the present invention. Any changes, substitutions, combinations, simplifications, modifications, etc. made by those skilled in the art without departing from the spirit and principles of the present invention shall be considered as equivalent replacement modes and shall be included in the protection scope of the present invention.

Claims

1. A low ripple and low harmonic power charger, characterized by: Its internal circuit includes AC input and overcurrent protection circuit, EMI filter electromagnetic anti-interference circuit, harmonic improvement circuit, rectifier filter circuit, PWM control IC and MOSFET tube drive circuit, high-frequency transformer conversion circuit, output rectifier filter circuit, MCU protection and charging control circuit, loop control circuit, load short circuit and reverse plug-in protection circuit and output low ripple and EMI circuit; The mains input and overcurrent protection circuit is connected to the harmonic improvement circuit through the EMI filter electromagnetic anti-interference circuit, the EMI filter electromagnetic anti-interference circuit is provided with a filter inductor NF1, the neutral line of the harmonic improvement circuit is connected in series with a common mode inductor L1, and the neutral line and the live line of the harmonic improvement circuit are connected to the filter inductor NF2; the AC output end of the harmonic improvement circuit is connected to the input end of the rectifier bridge BD1 of the rectifier filter circuit, and the DC output ends of the rectifier bridge BD1 are connected to a parallel circuit composed of filter capacitors C1 and C2. The positive electrode of the output end of the rectifier bridge BD1 of the rectifier filter circuit is connected to the positive end of the primary first winding of the high-frequency transformer T1 of the high-frequency transformer conversion circuit, and the negative end of the primary first winding is connected to the PWM control IC and MOSFET tube drive circuit containing the MOS tube Q1, the negative end of the primary first winding is connected to the drain of the MOS tube Q1, and the source of the MOS tube Q1 is connected to PGND through the resistor R7; the gate of the MOS tube Q1 is connected to the PWM control IC chip U1 of the PWM control IC and MOSFET tube drive circuit; Both ends of the secondary first winding of the high-frequency transformer T1 are connected to the output rectifier and filter circuit, a diode D10 is connected in series on the positive line of the output rectifier and filter circuit, both ends of the diode D10 are connected in parallel with a series circuit consisting of a plurality of resistors and a capacitor C14, and a parallel circuit consisting of a capacitor C5, a resistor R37, a resistor R38, a resistor R39, and a resistor R40 is connected between the positive and negative lines of the output rectifier and filter circuit; the positive output end of the output rectifier and filter circuit is output to the positive output end of the charger after passing through one inductor coil in the common mode inductor NF3 of the output low ripple and EMI circuit 11; the negative pole of the output rectifier and filter circuit is connected to GND, and the negative pole of the output rectifier and filter circuit is connected to the negative line of the load short circuit and reverse plug-in protection circuit, and the negative The load short circuit and reverse plug-in circuit includes a thyristor Q2 for preventing current backflow and a transistor Q7 for preventing load short circuit; the control electrode of the thyristor Q2 is connected to the control output terminal DRIVER1 of the intelligent control chip U2 of the MCU protection and charging control circuit through a resistor R60, and the model of the chip U2 is simHT45F5Q; the negative line of the load short circuit and reverse plug-in protection circuit is output to the negative output terminal of the charger after passing through another inductor coil in the common mode inductor NF3; the intelligent control chip U2 of the MCU protection and charging control circuit is connected to the input terminal of the optocoupler U3 in the loop control circuit, and the output terminal of the optocoupler U3 is connected to the feedback input terminal of the PWM control IC chip U1 of the PWM control IC and MOSFET tube drive circuit.

2. The low ripple and low harmonic power charger according to claim 1, characterized in that: The mains input and overcurrent protection circuit is provided with an overcurrent protection fuse F1.

3. The low ripple and low harmonic power charger according to claim 1, characterized in that: The model of the high frequency transformer T1 is PQ3225.

4. The low ripple and low harmonic power charger according to claim 1, characterized in that: The PWM control IC chip U1 of the PWM control IC and MOSFET tube drive circuit is RM6500S.

5. The low ripple and low harmonic power charger according to claim 1, characterized in that: The model of the optocoupler U3 in the loop control circuit is EL817.

6. The low ripple and low harmonic power charger according to claim 1, characterized in that: The chip U2 of the MCU protection and charging control circuit is also connected to a power device or an ambient temperature over-temperature protection and detection circuit. The over-temperature protection and detection circuit includes thermistors RT2 and RT3. The detection signal ends derived from the thermistors RT2 and RT3 are respectively connected to the detection input pins of the chip U2.

7. The low ripple and low harmonic power charger according to claim 1, characterized in that: The loop control circuit is also connected to an LED charging indicator LED1, and the LED1 is a dual-way indicator light, which is respectively connected to the output control pins of the chip U2.

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