Switching power supply with low power consumption and high efficiency

Abstract

The utility model discloses a switching power supply with low power consumption and high efficiency, which comprises a switching power supply main circuit, and the switching power supply main circuit comprises a mains supply input filter circuit, an input rectification and filter circuit, a switching circuit, a transformer and an output rectification and filter circuit. The switching power supply also comprises a voltage stabilization control circuit, and the voltage stabilization control circuit comprises a feedback protection circuit for sampling an output signal of the output end of the switching power supply main circuit, and a voltage stabilization circuit for processing the sampling signal to generate a control signal and connecting the control signal with the switching circuit. And an isolation device for isolating the input end and the output end of the switching power supply main circuit is arranged between the feedback protection circuit and the voltage stabilizing circuit. According to the utility model, the input and output ends of the switching power supply main circuit are isolated by the transformer in the switching power supply main circuit, and the optocoupler isolation is adopted in the feedback circuit, so that the requirements of users are met.

Description

Technical Field

[0001] The utility model relates to the field of switching power supplies, in particular to a switching power supply with low power consumption and high efficiency. The switching power supply is suitable for use with a class D power amplifier. Background Art

[0002] Class D amplifier refers to Class D audio power amplifier (sometimes also called digital amplifier). An amplifier that drives a speaker by controlling the ON / OFF of a switch unit is called a Class D amplifier. Class D amplifiers were first proposed in 1958 and have gradually become popular in recent years. They have been on the market for many years. Compared with general linear Class AB amplifier circuits, Class D amplifiers have the characteristics of high efficiency and small size.

[0003] At present, the driving signal of the power tube of the Class D amplifier is obtained by comparing the signal source with the sawtooth filter signal, and the working current is supplied by the power supply of the previous amplifier, which is generally a switching power supply. The utility model patent with announcement number CN203562970 U discloses a switching power supply for a 1000W Class D amplifier. The switching power supply for a 1000W class D power amplifier comprises an EMC filter circuit, a rectifier filter circuit, a transformer and an output rectifier filter circuit connected in sequence, a PWM regulation control circuit and a PWM drive circuit are connected between the rectifier filter circuit and the transformer, a power-on delay start circuit, an overvoltage and undervoltage protection circuit whose input signal is connected to an AC alternating current signal, and a DC output protection circuit whose input signal is connected to the class D power amplifier are also electrically connected to the PWM regulation control circuit, and the PWM regulation control circuit comprises a PWM control chip U2 of SG3525 and a peripheral circuit, and the PWM drive circuit comprises a PWM drive chip U1 of model IR2110 and a peripheral switch tube circuit, and the PWM drive chip U1 is respectively connected to pins 11, 12, and 14 of the PWM control chip U2 through pins 12, 13, and 14, and pins 1 and 8 of the PWM drive chip U1 are connected to both ends of the primary winding of the transformer through the peripheral switch tube circuit. Although such a Class D amplifier pre-stage power supply uses an EMS filter circuit to filter out some of the noise that enters the power supply with the AC power supply, it does not isolate the AC power input from the power supply DC output. The front-end switching power supply may affect the subsequent Class D amplifier and cannot meet user requirements. Summary of the invention

[0004] The utility model aims at the deficiency that the current switching power supply cannot meet the requirements of users for class D power amplifiers, and provides a low-power and high-efficiency switching power supply. The switching power supply is provided with isolation devices at the input and output ends of the switching power supply main circuit to prevent the mains end from affecting the power amplifier.

[0005] The technical scheme adopted by the utility model is: a low-power consumption and high-efficiency switching power supply, including a switching power supply main circuit, the switching power supply main circuit includes a mains input filter circuit, an input rectifier and filter circuit, a switch circuit, a transformer, and an output rectifier and filter circuit; after the mains is filtered by the mains input filter circuit and rectified and filtered by the input rectifier and filter circuit to form direct current, the mains is inverted by the switch circuit to form alternating current with a set power and enters the two ends of the primary coil of the transformer, and the alternating current with a set voltage output at the two ends of the secondary coil of the transformer is rectified and filtered by the output rectifier and filter circuit to form a direct current output; and also includes a voltage stabilization control circuit, the voltage stabilization control circuit includes a feedback protection circuit for sampling an output signal at an output end of the switching power supply main circuit and a voltage stabilization circuit for processing the sampled signal to generate a control signal connected to the switching circuit, and an isolation device for isolating the input and output ends of the switching power supply main circuit is arranged between the feedback protection circuit and the voltage stabilization circuit.

[0006] Furthermore, in the above-mentioned low-power and high-efficiency switching power supply: the voltage stabilization control circuit also includes a remote start module for realizing remote start, the remote start module is connected to the switching circuit, and includes an isolation device that is isolated from the input end of the main circuit of the switching power supply.

[0007] Furthermore, the above-mentioned low-power and high-efficiency switching power supply also includes: a second switching circuit, a second transformer, and a second output rectifier and filter circuit. The second switching circuit, the second transformer, and the second output rectifier and filter circuit are arranged at the output end of the input rectifier and filter circuit, and are in parallel with the switching circuit, the transformer, and the output rectifier and filter circuit.

[0008] Furthermore, in the above-mentioned low-power and high-efficiency switching power supply: the voltage stabilization control circuit also includes a second feedback protection circuit for sampling the output signal of the output end of the second output rectifier and filter circuit and a second voltage stabilization circuit for processing the sampled signal to generate a control signal connected to the second switching circuit, and an isolation device is provided between the second feedback protection circuit and the second voltage stabilization circuit.

[0009] Furthermore, in the above-mentioned low-power consumption and high-efficiency switching power supply: the isolation device adopts optocoupler isolation.

[0010] Furthermore, in the above-mentioned low-power and high-efficiency switching power supply: the switching circuit adopts a switch control chip U2 of model NCP1380C, including a switch tube Q7, and the switch tube Q7 is a CMOS tube, whose source and drain are respectively connected to the out-of-phase end of the primary coil of the transformer T3 and the HV-end of the DC power output by the input rectification and filtering circuit, and its gate is connected to the DRV pin of the switch control chip U2; the 2nd pin and the 7th pin of the switch control chip U2 are respectively connected to the feedback protection circuit and the operation start module through optical coupling.

[0011] Furthermore, in the above-mentioned low-power consumption and high-efficiency switching power supply: a driving circuit with a transistor Q9 as a core is also provided between the DRV pin of the switch control chip U2 and the gate of the switch tube Q7.

[0012] Furthermore, in the above-mentioned low-power consumption and high-efficiency switching power supply: an amplification circuit is also provided between the 2nd pin and the 7th pin of the switch control chip U2 and the optical coupler.

[0013] In the utility model, a transformer is used in the switching power supply main circuit to isolate the input and output ends of the switching power supply main circuit, and an optical coupler is used in the feedback circuit to meet the needs of users.

[0014] The present invention is described in more detail below in conjunction with specific embodiments and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a principle block diagram of a low-power and high-efficiency switching power supply according to Embodiment 1 of the utility model;

[0016] Figure 2 This is a mains input filter circuit, an input rectifier and filter circuit of Embodiment 1 of the utility model;

[0017] Figure 3 This is a schematic diagram of the switch circuit of Embodiment 1 of the utility model;

[0018] Figure 4 This is the output rectification and filtering circuit diagram of Embodiment 1 of the utility model;

[0019] Figure 5 This is the feedback comparison circuit of Example 1 of the utility model. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0021] Embodiment 1 of the utility model discloses a new switching power supply for replacing a traditional transformer. The new switching power supply has low power consumption, high efficiency and significant energy-saving effect. The power loss of the switching power supply is low, and its efficiency is usually above 80%, while the linear power supply is generally only about 40%. The switching power supply has a significant energy-saving effect. The switching power supply does not have a bulky power frequency transformer and does not require a large heat sink. Thereby reducing the volume and weight of the power supply. Its volume and weight are usually only about 30% of that of a linear power supply.

[0022] like Figure 1 As shown, the low-power and high-efficiency switching power supply of this embodiment utilizes electronic switching devices (such as transistors, field-effect transistors, thyristors, etc.) to continuously "turn on" and "turn off" the electronic switching devices through a control circuit, so that the electronic switching devices perform pulse modulation on the input voltage, thereby realizing DC / AC, DC / DC voltage conversion, as well as adjustable output voltage and automatic voltage stabilization.

[0023] like Figure 1 As shown: The low-power and high-efficiency switching power supply of this embodiment is mainly composed of four parts: the main circuit, the control circuit, the detection circuit and the auxiliary power supply. The main circuit refers to the main circuit of the switching power supply, which is composed of the mains input filter circuit, the input rectifier and filter circuit, the switch circuit, the transformer, and the output rectifier and filter circuit connected in sequence; the mains is filtered by the mains input filter circuit, and then rectified and filtered by the input rectifier and filter circuit to form direct current, which is then inverted by the switch circuit to form alternating current with a set power and enters the two ends of the primary coil of the transformer. The alternating current with a set voltage output at the two ends of the secondary coil of the transformer is rectified and filtered by the output rectifier and filter circuit to form a direct current output; as shown Figure 1 As shown, the AC input filter circuit, input rectification and filtering circuit, switch circuit, transformer, output rectification and filtering circuit are connected in sequence, with the AC signal and DC output of the AC power at both ends respectively. The transformer is set between the input and output, and actually plays an isolation role.

[0024] like Figure 1 As shown, the present embodiment also includes a voltage stabilization control circuit, which controls the output stability of the switching power supply. The voltage stabilization control circuit includes a feedback protection circuit for sampling an output signal at an output end of a main circuit of the switching power supply and a voltage stabilization circuit for processing the sampled signal to generate a control signal connected to the switching circuit. An isolation device for isolating the input and output ends of the main circuit of the switching power supply is provided between the feedback protection circuit and the voltage stabilization circuit. Here, the isolation device uses an optical coupler. Like the isolation transformer in the main circuit, the optical coupler can also be used to isolate the input and output ends of the switching power supply.

[0025] like Figure 1As shown, in this embodiment, a second switch power supply output path is also included, including a second switch circuit, a second transformer, and a second output rectifier and filter circuit. The second switch circuit, the second transformer, and the second output rectifier and filter circuit are arranged at the output end of the input rectifier and filter circuit, and are in parallel with the switch circuit, the transformer, and the output rectifier and filter circuit. The voltage stabilization control circuit also includes a second feedback protection circuit for sampling the output signal at the output end of the second output rectifier and filter circuit and a second voltage stabilization circuit for processing the sampled signal to generate a control signal connected to the second switch circuit. An optical coupler is arranged between the second feedback protection circuit and the second voltage stabilization circuit.

[0026] In this embodiment, the mains input filter circuit, input rectifier and filter circuit are as follows: Figure 2 As shown, the L phase and N phase of the mains are connected to the mains input filter circuit to filter out the high frequency part. The mains input filter circuit includes two common film inductors LF1 and LF2, wherein the model of the front common film inductor LF1 can be LF024, the L phase of the mains is connected to the first pin of the common film inductor LF1 after passing through the fuse F1, and the N phase of the mains is directly connected to the second pin of the common film inductor LF1. A filter capacitor CX1 and a filter resistor are connected in parallel between the first and second pins of the common film inductor LF1. The filter resistor is generally about 1M. In this embodiment, the filter resistor is composed of a resistor R7 with a smaller resistance value, Resistors R8 and R8A are connected in series. These three resistors are 390K respectively. Common film inductor LF2 is located after common film inductor LF1. Pins 3 and 4 of common film inductor LF1 are connected to pins 1 and 2 of common film inductor LF2 respectively. A voltage regulator Z1 is used between pins 1 and 2 of common film inductor LF2. Pins 1 and 2 of common film inductor LF2 are also grounded by capacitors C2 and C3 respectively to ground the FM signal on the wire. A filter capacitor C5 and two resistors R1 and R2 are connected in series in parallel between pins 3 and 4 of common film inductor LF2. These two resistors are 1M resistors respectively.

[0027] After the AC power is input into the filter circuit, the 220VAC AC power with high-frequency signals filtered out enters the input rectification and filtering circuit to complete the AC-DC conversion. Here, the format rectifier stack BD1 is used for rectification, and then the filter circuit composed of capacitor C31 and thermal resistor N1 forms a stable DC output from the HV+ and HV- poles. The model of the thermal resistor N1 is 2.5D-11.

[0028] The AC input filter circuit, input rectification and filtering circuit output the DC power from the HV+ and HV- poles to the switch circuit, such as Figure 3As shown, the switch circuit adopts a switch control chip U2 of model NCP1380C, including a switch tube Q7, which is a CMOS tube. Its source and drain are respectively connected to the out-of-phase end of the primary coil of the transformer T3 and the HV- end of the DC output of the input rectification and filtering circuit, and its gate is connected to the DRV pin of the switch control chip U2; the 2nd pin and the 7th pin of the switch control chip U2 are respectively connected to the feedback protection circuit and the operation start module through optical coupling. A driving circuit with the triode Q9 as the core is also arranged between the DRV pin of the switch control chip U2 and the gate of the switch tube Q9. An amplification circuit is also arranged between the 2nd pin and the 7th pin of the switch control chip U2 and the optical coupler.

[0029] HV+ and HV- are added to the two ends of the primary coil of the transformer respectively, and the switch tube Q7 is set between the out-of-phase end of the primary coil and HV- to control the switch tube to turn on / off and invert into AC. The switch control chip U2 realizes the on / off frequency of the switch tube Q7, which is a PWM signal. The duty cycle of the PWM signal is used to control the output power, and the 2nd and 7th pins of the switch control chip U2 are respectively connected to the external control signal, which is a negative feedback signal and an external remote control signal, respectively. They are all isolated and input into the 2nd and 7th pins of the switch control chip using the optocoupler U4 and the optocoupler U5. In this embodiment, an amplifier circuit with a transistor Q9 as the core is used between the 6th pin of the switch control chip U2, that is, the DRV end and the gate of the switch tube Q7, and two amplifiers with transistors Q10 and Q3 as the core are used between the optocoupler U4 and the optocoupler U5 and the 2nd and 7th pins of the switch control chip.

[0030] like Figure 4 The output rectification and filtering circuit in this embodiment is shown. At both ends of the secondary coil of the transformer, the rectifier diode D16 performs half-wave rectification, and then uses four associated electrolytic capacitors C45-C48 for filtering. The model of these four electrolytic capacitors is 470UF / 63V, and then the output coupling resistors R89, R90, and R112 are connected in parallel between the two ends of the output.

[0031] like Figure 5 The feedback comparison circuit of this embodiment is shown, in which the TL341 three-terminal adjustable parallel regulator U7 is used.

Claims

1. A low-power consumption and high-efficiency switching power supply, comprising a switching power supply main circuit, wherein the switching power supply main circuit comprises a mains input filter circuit, an input rectifier and filter circuit, a switch circuit, a transformer, and an output rectifier and filter circuit; the mains is filtered by the mains input filter circuit and then rectified and filtered by the input rectifier and filter circuit to form direct current, which is then inverted by the switch circuit to form alternating current of set power and enters the two ends of the primary coil of the transformer, and the alternating current of set voltage output at the two ends of the secondary coil of the transformer is rectified and filtered by the output rectifier and filter circuit to form a direct current output; characterized in that: It also includes a voltage stabilization control circuit, which includes a feedback protection circuit for sampling an output signal at an output end of the switching power supply main circuit and a voltage stabilization circuit for processing the sampled signal to generate a control signal connected to the switching circuit. An isolation device for isolating the input and output ends of the switching power supply main circuit is provided between the feedback protection circuit and the voltage stabilization circuit.

2. The low power consumption and high efficiency switching power supply according to claim 1, characterized in that: The voltage stabilizing control circuit also includes a remote start module for realizing remote start, the remote start module is connected to the switch circuit, and includes an isolation device that is isolated from the input end of the switch power supply main circuit.

3. The low power consumption and high efficiency switching power supply according to claim 2, characterized in that: It also includes a second switch circuit, a second transformer, and a second output rectifier and filter circuit. The second switch circuit, the second transformer, and the second output rectifier and filter circuit are arranged at the output end of the input rectifier and filter circuit and are in parallel with the switch circuit, the transformer, and the output rectifier and filter circuit.

4. The low power consumption and high efficiency switching power supply according to claim 3, characterized in that: The voltage stabilization control circuit also includes a second feedback protection circuit for sampling the output signal at the output end of the second output rectifier and filter circuit and a second voltage stabilization circuit for processing the sampled signal to generate a control signal connected to the second switch circuit. An isolation device is provided between the second feedback protection circuit and the second voltage stabilization circuit.

5. The low power consumption and high efficiency switching power supply according to any one of claims 1 to 4, characterized in that: The isolation device adopts optical coupling isolation.

6. The low power consumption and high efficiency switching power supply according to claim 5, characterized in that: The switch circuit adopts a switch control chip U2 of model NCP1380C, including a switch tube Q7. The switch tube Q7 is a CMOS tube, and its source and drain are respectively connected to the out-of-phase end of the primary coil of the transformer T3 and the HV-end of the direct current output by the input rectification and filtering circuit, and its gate is connected to the DRV pin of the switch control chip U2; the 2nd pin and the 7th pin of the switch control chip U2 are respectively connected to the feedback protection circuit and the remote start module through optical coupling.

7. The low power consumption and high efficiency switching power supply according to claim 6, characterized in that: A driving circuit with a transistor Q9 as the core is also provided between the DRV pin of the switch control chip U2 and the gate of the switch tube Q7.

8. The low power consumption and high efficiency switching power supply according to claim 6, characterized in that: An amplifier circuit is also provided between the 2nd and 7th pins of the switch control chip U2 and the optocoupler.

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