Rectifier circuit and power supply equipment

Abstract

This invention provides a rectifier circuit and power supply device. The rectifier circuit includes: a primary coil; a secondary coil that works in conjunction with the primary coil; a first rectifier diode with its first end connected to the first end of the secondary coil; an output capacitor with its first end connected to the second end of the secondary coil and its second end connected to the second end of the first rectifier diode; a first power supply unit with its first input end connected to the first end of the first rectifier diode, its second input end connected to the first end of the output capacitor, and its output end connected to the control end of the first rectifier diode; and a second power supply unit with its input end connected to the first end of the output capacitor and its output end connected to the control end of the first rectifier diode. This invention improves the rectification effect, thereby increasing power supply efficiency.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power electronic conversion, and in particular, to a rectifier circuit and a power supply device. Background Art

[0002] As the power of power products increases, the loss of secondary side rectifier devices is also increasing. Non-synchronous rectification cannot meet the application requirements, and low on-resistance power MOSFETs are needed to replace diodes to achieve synchronous rectification. When using power MOSFETs for rectification, a certain voltage (above the threshold voltage) needs to be applied to the gate to turn on the MOSFET to complete the rectification.

[0003] In the related art, there is a problem that the rectification effect of the rectification circuit is poor, resulting in low power efficiency.

[0004] With respect to the above-mentioned problems existing in the related technologies, no effective solution has been proposed yet. Summary of the invention

[0005] The embodiments of the present invention provide a rectifier circuit and a power supply device, so as to at least solve the problem in the related art that the rectifier circuit has a poor rectifier effect and thus leads to low power efficiency.

[0006] According to one embodiment of the present invention, there is provided a rectifier circuit, comprising: a primary coil;

[0007] A secondary coil, wherein the secondary coil cooperates with the primary coil; a first rectifier tube, wherein the first end of the first rectifier tube is connected to the first end of the secondary coil; an output capacitor, wherein the first end of the output capacitor is connected to the second end of the secondary coil, and the second end of the output capacitor is connected to the second end of the first rectifier tube; a first power supply unit, wherein the first input end of the first power supply unit is connected to the first end of the first rectifier tube, the second input end of the first power supply unit is connected to the first end of the output capacitor, and the output end of the first power supply unit is connected to the control end of the first rectifier tube; a second power supply unit, wherein the input end of the second power supply unit is connected to the first end of the output capacitor, and the output end of the second power supply unit is connected to the control end of the first rectifier tube; wherein, in the process in which the output voltage of the output capacitor is less than a preset threshold voltage, the first power supply unit collects electric energy in the secondary coil, and drives the first rectifier tube in the case in which the output voltage of the first power supply unit is a first voltage; and in the process in which the output voltage of the output capacitor is greater than or equal to the preset threshold voltage, the second power supply unit drives the first rectifier tube.

[0008] In an exemplary embodiment, the first power supply unit includes: a first capacitor, a second capacitor, a first diode and a second diode, the first end of the first capacitor is connected to the first end of the first rectifier, the second end of the first capacitor is connected to the first end of the first diode and the second end of the second diode, the second end of the first diode is connected to the first end of the second capacitor, the first end of the second diode is connected to the second end of the second capacitor, the first end of the second capacitor is connected to the control end of the first rectifier, and the second end of the second capacitor is connected to the first end of the output capacitor; wherein the first diode only allows current to flow from the second end of the first capacitor to the first end of the second capacitor, and the second diode only allows current to flow from the first end of the output capacitor to the second end of the first capacitor.

[0009] In an exemplary embodiment, the first power supply unit further includes: the first power supply unit further includes: a first resistor, and the first capacitor is connected to the first end of the secondary coil through the first resistor.

[0010] In an exemplary embodiment, the first power supply unit further includes: a third capacitor and a first zener diode, the first end of the third capacitor is connected to the first end of the second capacitor, the second end of the third capacitor is grounded, and the first zener diode is connected in parallel with the third capacitor.

[0011] In an exemplary embodiment, the first power supply unit further includes a fourth capacitor, a first end of the fourth capacitor is connected to the first end of the third capacitor, and a second end of the fourth capacitor is grounded.

[0012] In an exemplary embodiment, the first power supply unit further includes a second resistor, a first end of the first voltage regulator diode is connected to a first end of the third capacitor through the second resistor, and a second end of the first voltage regulator diode is grounded.

[0013] In an exemplary embodiment, the rectifier circuit further includes a switching unit, the output end of the first power supply unit is connected to the switching unit, the output end of the second power supply unit is connected to the switching unit, and the output end of the switching unit is connected to the control end of the first rectifier circuit.

[0014] In an exemplary embodiment, the second power supply unit includes a first transistor and a second zener diode, the first electrode of the first transistor and the first control electrode of the first transistor are both connected to the first end of the output capacitor, the second electrode of the first transistor is connected to the switching unit, the first end of the second zener diode is connected to the first control electrode, and the second end of the second zener diode is grounded; the first end of the second capacitor is connected to the switching unit, and the switching unit is also connected to the control end of the first rectifier, and the switching unit is used to connect the first end of the second capacitor or the second electrode of the first transistor to the control end.

[0015] In an exemplary embodiment, the second power supply unit further includes a third resistor, and the first control electrode is connected to the first end of the output capacitor through the third resistor.

[0016] In an exemplary embodiment, the rectifier circuit further includes a drive control device, and the switching unit is connected to the control end of the first rectifier tube through the drive control device.

[0017] In an exemplary embodiment, the rectifier circuit further includes a second rectifier tube, and the second rectifier tube is connected to one end of the primary coil.

[0018] According to another embodiment of the present invention, a power supply device is provided, comprising: the rectifier circuit described in any one of the above embodiments and a power supply, wherein the power supply is connected to the primary coil.

[0019] Through the present invention, the rectifier circuit includes a primary coil, a secondary coil, a first rectifier tube, an output capacitor, a first power supply unit and a second power supply unit. The secondary coil cooperates with the primary coil; the first end of the first rectifier tube is connected to the first end of the secondary coil; the first end of the output capacitor is connected to the second end of the secondary coil, and the second end of the output capacitor is connected to the second end of the first rectifier tube; the first input end of the first power supply unit is connected to the first end of the first rectifier tube, the second input end of the first power supply unit is connected to the first end of the output capacitor, and the output end of the first power supply unit is connected to the control end of the first rectifier tube; the second power supply unit, the input end of the second power supply unit is connected to the first end of the output capacitor, and the output end of the second power supply unit is connected to the control end of the first rectifier tube. Since the first power supply unit can collect the electric energy in the secondary coil when the output voltage of the output capacitor is less than the preset threshold voltage, and drive the first rectifier when the output voltage of the first power supply unit is the first voltage; when the output voltage of the output capacitor is greater than or equal to the preset threshold voltage, the first rectifier is driven by the second power supply unit, so that the energy on the secondary winding of the transformer is collected by the first power supply unit, and after the conversion of the hardware circuit, a stable voltage is formed to drive the first rectifier. During the process of circuit startup and overcurrent short circuit, the driving voltage of the first rectifier can be maintained above the start-up voltage, and the first rectifier can be fully turned on to improve the power supply efficiency. Therefore, the problem of poor rectification effect of the rectifier circuit in the related art leading to low power supply efficiency can be solved, so as to improve the rectification effect and thus improve the power supply efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the secondary side synchronous rectification self-driven power supply circuit;

[0021] Figure 2 This is a schematic diagram of the secondary side synchronous rectification external drive power supply circuit;

[0022] Figure 3 is a circuit diagram of a rectifier circuit according to an embodiment of the present invention;

[0023] Figure 4 is a circuit diagram of a first power supply unit according to an embodiment of the present invention;

[0024] Figure 5 is a circuit diagram of a second power supply unit according to an embodiment of the present invention;

[0025] Figure 6 4 is a flowchart of a switching unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and in combination with the embodiments.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0028] As the power of power products increases, the loss of secondary side rectifier devices is also increasing. Non-synchronous rectification cannot meet the application requirements. It is necessary to use power MOSFET with low on-resistance to replace diodes to achieve synchronous rectification. When using power MOSFET for rectification, a certain voltage (above the threshold voltage) needs to be applied to the gate to turn on the MOSFET to complete the rectification. The driving modes of secondary side synchronous rectification can include self-driving and external driving. The schematic diagram of the secondary side synchronous rectification self-driving power supply circuit can be found in the attached Figure 1 ,like Figure 1 As shown, after the circuit works, the voltage Vo on the output capacitor Cout1 gradually increases until it stabilizes. The secondary output voltage Vo is used to forward bias the base of the transistor Q1. Q1 works in the amplification state, and the e-pole voltage = b-pole voltage -0.7V, providing a driving voltage to the SR1 G-pole. At the same time, the Z1 voltage is clamped to prevent the G-pole voltage from being too high. However, during the startup process, the secondary output Vo has not been established normally, resulting in the SR driving voltage being too low to drive the tube. In the case of overcurrent short circuit, the output voltage Vo is very low, resulting in a low SR driving voltage, which is prone to insufficient driving and damage to the power tube.

[0029] The schematic diagram of the secondary-side synchronous rectification external drive power supply circuit can be found in the attached Figure 2 ,like Figure 2 As shown, after the control IC works, two PWM1 and PWM2 with the same phase or opposite direction and a certain dead zone are generated. PWM1 drives the primary main MOS, and PWM2 is converted into PWM2_s through the transformer isolation drive to drive the secondary SR2. The final PWM1 and PWM2_s have opposite timing and a driving voltage waveform with a certain dead zone. However, when using external drive, it is necessary to find a control IC with multiple drive outputs, which is not universal and difficult to replace. In addition, a specially designed isolation drive circuit is required, which is complex and large in size. The primary and secondary side drives have a fixed dead time (depending on the control IC). Energy is not stored and transferred during this period, which affects efficiency.

[0030] In view of the above problems existing in the related art, the following embodiments are proposed.

[0031] In this embodiment, a rectifier circuit is provided. Figure 3 is a circuit diagram of a rectifier circuit according to an embodiment of the present invention, such as Figure 3 As shown, the rectifier circuit includes:

[0032] Primary coil;

[0033] A secondary coil, the secondary coil cooperates with the primary coil;

[0034] A first rectifier tube, wherein a first end of the first rectifier tube is connected to a first end of the secondary coil;

[0035] an output capacitor, wherein a first end of the output capacitor is connected to a second end of the secondary coil, and a second end of the output capacitor is connected to a second end of the first rectifier tube;

[0036] A first power supply unit, wherein a first input end of the first power supply unit is connected to a first end of the first rectifier tube, a second input end of the first power supply unit is connected to a first end of the output capacitor, and an output end of the first power supply unit is connected to a control end of the first rectifier tube;

[0037] A second power supply unit, wherein an input end of the second power supply unit is connected to the first end of the output capacitor, and an output end of the second power supply unit is connected to the control end of the first rectifier tube;

[0038] Wherein, when the output voltage of the output capacitor is less than a preset threshold voltage, the first power supply unit collects electric energy in the secondary coil, and drives the first rectifier tube when the output voltage of the first power supply unit is a first voltage; when the output voltage of the output capacitor is greater than or equal to the preset threshold voltage, the second power supply unit drives the first rectifier tube.

[0039] In the above embodiment, the rectifier circuit can be applied in an isolated power supply. The primary coil can be the primary coil of a transformer, the secondary coil can be the secondary coil of a transformer, the primary coil is coupled with the secondary coil, and the primary coil is connected to the input voltage. The first end De of the secondary coil can be connected to the first end of the first rectifier tube, and the second end Vo of the secondary coil can be connected to the first end of the output capacitor Cout. The second end of the output capacitor Cout can be connected to the second end of the first rectifier tube. The first power supply unit can be a charge pump power supply. The first input end of the first power supply unit is connected to the first end of the first rectifier tube, that is, the first input end of the first power supply unit can be connected to the first end of the secondary coil. When the primary coil is powered on, the voltage on the output capacitor begins to build up, but has not yet reached the preset threshold voltage. The first power supply unit can collect the electric energy on the secondary coil. After a period of power-on, the first power supply unit can quickly stabilize to the VCC voltage to supply power to the first rectifier tube, and the secondary side works in a synchronous rectification state. During the power-off process, the output voltage v0 of the output capacitor decreases. When it is less than a preset threshold voltage, the first power supply unit collects energy in the secondary coil to drive the first rectifier tube.

[0040] In the above embodiment, the second power supply unit may be a Vo power supply circuit. When the output voltage of the output capacitor is greater than a preset threshold voltage, the first rectifier tube of the second power supply unit may be used.

[0041] According to the present invention, the rectifier circuit includes a primary coil, a secondary coil, a first rectifier tube, an output capacitor and a first power supply unit. The secondary coil cooperates with the primary coil; the first end of the first rectifier tube is connected to the first end of the secondary coil; the first end of the output capacitor is connected to the second end of the secondary coil, and the second end of the output capacitor is connected to the second end of the first rectifier tube; the first power supply unit, the first input end of the first power supply unit is connected to the first end of the first rectifier tube, the second input end of the first power supply unit is connected to the first end of the output capacitor, and the output end of the first power supply unit is connected to the control end of the first rectifier tube; the second power supply unit, the input end of the second power supply unit is connected to the first end of the output capacitor, and the output end of the second power supply unit is connected to the control end of the first rectifier tube; wherein, in the process that the output voltage of the output capacitor is less than the preset threshold voltage, the first power supply unit collects the electric energy in the secondary coil, and drives the first rectifier tube when the output voltage of the first power supply unit is the first voltage; in the process that the output voltage of the output capacitor is greater than or equal to the preset threshold voltage, the second power supply unit drives the first rectifier tube. Therefore, the problem of poor rectification effect of the rectification circuit in the related art resulting in low power efficiency can be solved, thereby achieving the effect of improving the rectification effect and further improving the power efficiency.

[0042] In an exemplary embodiment, the first power supply unit includes: a first capacitor, a second capacitor, a first diode and a second diode, the first end of the first capacitor is connected to the first end of the first rectifier, the second end of the first capacitor is connected to the first end of the first diode and the second end of the second diode, the second end of the first diode is connected to the first end of the second capacitor, the first end of the second diode is connected to the second end of the second capacitor, the first end of the second capacitor is connected to the control end of the first rectifier, and the second end of the second capacitor is connected to the first end of the output capacitor; wherein the first diode only allows current to flow from the second end of the first capacitor to the first end of the second capacitor, and the second diode only allows current to flow from the first end of the output capacitor to the second end of the first capacitor. In this embodiment, the circuit diagram of the first power supply unit can be found in the attached Figure 4 ,like Figure 4As shown, the first power supply unit may include a first capacitor C1, a second capacitor C2, a first diode D1 and a second diode D2. The first end of the first capacitor C1 is connected to the first end De of the secondary coil, that is, the first end of the first capacitor C1 is connected to the first end of the first rectifier tube, the second end of the second diode is connected to the second end of the second capacitor, and the second end of the second diode is also connected to the second end Vo of the secondary coil, that is, the second end of the second diode is also connected to the first end of the output capacitor Cout.

[0043] In the above embodiment, the voltage Vo on the secondary rectifier tube SR, i.e., the D pole of the first rectifier tube and the output capacitor Cout (i.e., the voltage across the secondary winding of the transformer) is collected through the charge pump circuit, i.e., the first power supply unit, and after voltage regulation, a stable voltage is output. The specific process of voltage regulation of the first power supply unit is: when De is low and Vo is high, the Vo→D2→C1→R1→De loop charges the C1 capacitor; when De is high and Vo is low, the De→R1→C1→D1→C2 loop charges the C2 capacitor; when power is just turned on or short-circuited due to overcurrent, when Vo is relatively low, C2 can also be directly charged through the De→R1→C1→D1→C2 loop.

[0044] In an exemplary embodiment, the first power supply unit further includes: the first power supply unit further includes: a first resistor, and the first capacitor is connected to the first end of the secondary coil through the first resistor. Figure 4 ,like Figure 4 As shown, the first power supply unit also includes a first resistor R1. The first capacitor can be connected to the first end of the secondary coil through the first electron. Connecting a first resistor R1 between the secondary coil and the first capacitor can effectively prevent the voltage at the end of the secondary coil De from being too large, which may cause the first capacitor to be broken down, thereby playing a role in protecting the circuit.

[0045] In an exemplary embodiment, the first power supply unit further includes: a third capacitor and a first voltage regulator diode, the first end of the third capacitor is connected to the first end of the second capacitor, the second end of the third capacitor is grounded, and the first voltage regulator diode is connected in parallel with the third capacitor. Figure 4 ,like Figure 4 As shown, the first power supply unit also includes a third capacitor C3 and a first voltage regulator diode Z1. When the power is just turned on or short-circuited due to overcurrent, when Vo is relatively low, C2 can be directly charged through the De→R1→C1→D1→C2 loop. Then the electricity on C2 is transferred to C3, and finally passes through the voltage regulator diode Z1 to output a stable voltage Vcc1.

[0046] In an exemplary embodiment, the first power supply unit further includes a fourth capacitor, a first end of the fourth capacitor is connected to the first end of the third capacitor, and a second end of the fourth capacitor is grounded. Figure 4 ,like Figure 4 As shown, the first power supply unit further includes a fourth capacitor C4, a first end of the fourth capacitor can be connected to the first end of the third capacitor, and a second end of the fourth capacitor can be grounded.

[0047] In an exemplary embodiment, the first power supply unit further includes a second resistor, the first end of the first voltage stabilizing diode is connected to the first end of the third capacitor via the second resistor, and the second end of the first voltage stabilizing diode is grounded. Figure 4 ,like Figure 4 As shown, the first power supply unit further includes a second resistor R2, and the first end of the third capacitor C3 can be connected to the first end of the first voltage regulator diode Z1 through the second resistor R2, and R2 can be used to adjust the voltage drop between C3 and Vcc1.

[0048] In an exemplary embodiment, the first power supply unit may further include: a first inductor, a second inductor, a third diode, and a fourth diode, wherein the first end of the first inductor is connected to the first end of the first rectifier, the second end of the first inductor is connected to the first end of the first diode and the second end of the second diode, the second end of the first diode is connected to the first end of the second inductor, the first end of the second diode is connected to the second end of the second inductor, the first end of the second inductor is connected to the control end of the first rectifier, and the second end of the second inductor is connected to the first end of the output capacitor; wherein the first diode only allows current to flow from the second end of the first inductor to the first end of the second inductor, and the second diode only allows current to flow from the first end of the output capacitor to the second end of the first inductor. In this embodiment, the secondary rectifier SR, i.e., the D pole of the first rectifier and the voltage Vo on the output capacitor Cout (i.e., the voltage across the secondary winding of the transformer) are collected through the charge pump circuit, i.e., the first power supply unit, and a stable voltage is output after voltage regulation. The specific process of voltage stabilization of the first power supply unit is: when De is low and Vo is high, the first inductor is charged through the circuit of Vo→D2→L1 (first inductor)→R1→De; when De is high and Vo is low, the second inductor is charged through the circuit of De→R1→L1→D1→L2 (second inductor); when power is just turned on or short-circuited due to overcurrent, when Vo is relatively low, the second inductor can also be directly charged through the circuit of De→R1→L1→D1→L2.

[0049] In the above embodiment, the first power supply unit may further include a third inductor and a second voltage regulator diode, the first end of the third inductor is connected to the first end of the second inductor, the second end of the third inductor is grounded, and the second voltage regulator diode is connected in parallel with the third inductor. When power is just turned on or short-circuited due to overcurrent, when Vo is relatively low, L2 can be directly charged through the De→R1→L1→D1→L2 loop. Then the electricity on L2 is transferred to L3 (the third inductor), and finally passes through the second voltage regulator diode Z2 to output a stable voltage Vcc1.

[0050] In the above embodiment, the first power supply unit further includes a fourth inductor, a first end of the fourth inductor is connected to the first end of the third inductor, and a second end of the fourth inductor is grounded.

[0051] In the above embodiment, the first power supply unit further includes a fourth resistor, the first end of the second voltage stabilizing diode is connected to the first end of the third inductor through the fourth resistor, and the second end of the second voltage stabilizing diode is grounded. The first end of the third inductor can be connected to the first end of the second voltage stabilizing diode Z2 through the fourth resistor, and the fourth resistor can be used to adjust the voltage drop between the third inductor and Vcc1.

[0052] In an exemplary embodiment, the rectifier circuit further includes a switching unit, the output end of the first power supply unit is connected to the switching unit, the output end of the second power supply unit is connected to the switching unit, and the output end of the switching unit is connected to the control end of the first rectifier circuit. In this embodiment, the rectifier circuit may also include a switching unit, the output ends of the first power supply unit and the second power supply unit are both connected to the switching unit, and the output end of the switching unit is connected to the control end of the first rectifier circuit. The switching unit can conduct the first power supply unit and the control end of the first rectifier circuit when the output voltage is less than a preset threshold voltage, and conduct the second power supply unit and the control end of the first rectifier circuit when the output voltage is greater than or equal to the preset threshold voltage.

[0053] In an exemplary embodiment, the second power supply unit includes a first transistor and a second voltage-stabilizing diode, the first electrode of the first transistor and the first control electrode of the first transistor are both connected to the first end of the output capacitor, the second electrode of the first transistor is connected to the switching unit, the first end of the second voltage-stabilizing diode is connected to the first control electrode, and the second end of the second voltage-stabilizing diode is grounded; the first end of the second capacitor is connected to the switching unit, and the switching unit is also connected to the control end of the first rectifier, and the switching unit is used to connect the first end of the second capacitor or the second electrode of the first transistor to the control end. In this embodiment, continue to refer to the attached Figure 3 ,like Figure 3As shown, the rectifier circuit may also include a second power supply unit, namely, a Vo power supply module and a switching unit, namely, a power supply switching unit, and the output end of the second power supply unit and the output end of the first power supply unit are both connected to the switching unit. The circuit diagram of the second power supply unit can be found in the attached Figure 5 ,like Figure 5 As shown, the second power supply unit includes a first transistor Q1 and a second voltage stabilizing diode Z2, the first control electrode of the first transistor Q1, i.e., the base, and the first electrode of Q1, i.e., the collector, are both connected to the second end Vo of the secondary coil, and the emitter of the first transistor Q1 is connected to the switching unit. The second end of the second voltage stabilizing diode is grounded, and the first end of the second voltage stabilizing diode is connected to the base of the first transistor Q1. The switching unit is used to connect the second capacitor of the first power supply unit to the control end of the first rectifier tube, or to connect the collector of the first transistor of the second power supply unit to the control end of the first rectifier tube.

[0054] In the above embodiment, the second power supply unit can use the voltage Vo on the output capacitor Cout to drive the be pole of the transistor Q1, thereby turning on Q1 and outputting Vcc2. When Vo does not reach the clamping value of Z2, Vcc2 changes with Vo; when Vo reaches the clamping value of Z2, Vcc2 is output stably, and the output voltage is equal to the Z2 regulated voltage value minus a be voltage drop of Q1.

[0055] In the above embodiment, when power is turned on, the voltage on the output capacitor begins to build up. Before the threshold voltage Vo_on is reached, the charge pump power supply module, that is, the first power supply unit, works to collect energy on De, and the secondary side first works in an asynchronous rectification state. After a switching cycle of power-on, the charge pump module collects energy on the secondary winding of the transformer, quickly stabilizes the voltage at the Vcc1 voltage, supplies power to the SR drive, and the secondary side works in a synchronous rectification state. As the output Vo voltage rises, it reaches the threshold voltage Vo_on and sets the hysteresis voltage Vo_on_h, and then switches to the Vo power supply module for power supply. As Vo continues to increase, the SR drive voltage amplitude also increases, and is finally clamped near the regulated value Vcc2, and the secondary side still works in a synchronous rectification state. During normal operation, the Vo power supply module is mainly used to power the drive module, and the secondary side works in a synchronous rectification state. The power-off process is similar to the power-on process. The Vo voltage drops. When it reaches the threshold voltage Vo_De and the hysteresis voltage Vo_De_h is set, it switches to the charge pump module to power the secondary SR driver until the energy of the charge pump is insufficient to maintain the voltage of Vcc1. The secondary side returns to the asynchronous rectification state until it shuts down. When an overcurrent or short-circuit fault occurs, the voltage Vo on the output capacitor is clamped at a very low level, lower than the threshold voltage (Vo_on-Vo_on_h) and Vo_De, and directly switches to the charge pump module to power the secondary SR driver. During overcurrent and short-circuit, the main MOS on the primary side will have a conduction time Ton. The charge pump module can obtain energy from the winding, namely De (the voltage on the winding is the input voltage / turn ratio, and the voltage value is higher than the regulated value Vcc1) to provide Vcc1 output.

[0056] In the above embodiment, the switching unit work flow chart can be found in the attached Figure 6 ,like Figure 6 As shown, the process includes:

[0057] Step S600, power on.

[0058] Step S602: the primary side main MOS tube is switched, the charge pump module (corresponding to the above-mentioned first power supply unit) collects energy, and the secondary side diode performs asynchronous rectification.

[0059] Step S604, whether the charge pump module voltage reaches VCC1, if the judgment result is yes, execute step S606, if the judgment result is no, execute step S602.

[0060] Step S606: the charge pump module supplies power to the secondary side SR driver.

[0061] Step S608, determine whether Vo≥Vo_on? Hysteresis Vo_on_h. If the judgment result is yes, execute step S610, if the judgment result is no, execute step S606.

[0062] Step S610: The Vo power supply module supplies power.

[0063] Step S612, startup is completed, Vo is stably established, and works normally, and the Vo power supply module supplies power.

[0064] Step S614, power off.

[0065] Step S616: the Vo power supply module supplies power.

[0066] Step S618, determine if Vo ≤ Vo_on? Hysteresis Vo_on_h. If the determination result is yes, execute step S620, if the determination result is no, execute step S616.

[0067] Step S620: the charge pump module supplies power to the secondary side SR driver.

[0068] Step S622, determine whether the voltage of the charge pump module is maintained at VCC1. If the determination result is yes, execute step S620, and if the determination result is no, execute step S624.

[0069] Step S624: asynchronous rectification of the secondary diode.

[0070] Step S626, power off is completed.

[0071] Step S628, overcurrent, short circuit.

[0072] Step S630: the charge pump module supplies power to the secondary side driver.

[0073] In an exemplary embodiment, the second power supply unit further includes a third resistor, and the first control electrode is connected to the first end of the output capacitor via the third resistor. Figure 5 ,like Figure 5 As shown, the second power supply unit further includes a third resistor R3, and the base of the first transistor can be connected to the first end of the output capacitor through the third resistor R3.

[0074] In an exemplary embodiment, the rectifier circuit further includes a drive control device, and the switching unit is connected to the control end of the first rectifier tube through the drive control device. Figure 3 ,like Figure 3 As shown, the rectifier circuit may further include a drive control device, and the drive control device may be connected to a power supply switching unit, and the power supply switching unit provides a stable voltage for the drive control device to drive the first rectifier tube to rectify.

[0075] In an exemplary embodiment, the rectifier circuit further includes a second rectifier tube, and the second rectifier tube is connected to one end of the primary coil. Figure 3 ,like Figure 3 As shown, the rectifier circuit may further include a second rectifier tube, and the second rectifier tube may rectify the primary coil under the drive of the control IC.

[0076] In an exemplary embodiment, the first power supply unit may further include a battery, the output end of the battery is connected to the switching unit, the output end of the second power supply unit is connected to the switching unit, the switching unit is connected to the control end of the first rectifier, and when it is detected that the output voltage of the output capacitor is less than the preset threshold voltage, the switching unit connects the battery to the control end of the first rectifier, and the first rectifier is driven by the battery. When the output voltage of the output capacitor is greater than or equal to the preset threshold voltage, the switching unit connects the second power supply unit to the control end of the first rectifier, and the first rectifier is driven by the second power supply unit. Set the hysteresis voltage Vo_on_h and Vo_De_h. When Vo rises, before reaching Vo_on, the secondary SR driver is powered by a battery. After reaching Vo_on, the secondary SR driver is powered by a Vo power supply module. When Vo drops, before reaching Von_De, the secondary SR driver is powered by a Vo power supply module. After reaching Von_De, the secondary SR driver is powered by a battery. If the output is overcurrent or short-circuited, Vo will be quickly pulled down, below the threshold voltage (Vo_on-Vo_on_h) and Vo_De, and the secondary SR driver is directly powered by a battery. Thus, dual power supply is achieved to ensure that the driving voltage of the secondary SR tube is sufficient.

[0077] In the aforementioned embodiment, in the secondary synchronous rectification application (flyback, forward, LLC and other topologies are applicable), dual power supply can be realized to supply power to the secondary SR driver, ensuring that the driving voltage amplitude is always maintained to meet the SR tube full conduction during startup, steady-state operation, overcurrent short circuit fault, etc. The energy on the secondary winding of the transformer is collected through the charge pump principle, and after conversion by the hardware circuit, a stable voltage is formed to supply power to the secondary SR tube driver. With Vo_on and Von_De as thresholds and hysteresis voltages Vo_on_h and Vo_De_h set, when Vo rises, before reaching Vo_on, the charge pump module is used to power the secondary SR driver, and after reaching Vo_on, the Vo power supply module is used to power the secondary SR driver; when Vo drops, before reaching Von_De, the Vo power supply module is used to power the secondary SR driver, and after reaching Von_De, the charge pump module is used to power the secondary SR driver; if the output has an overcurrent and short circuit, Vo will be quickly pulled down, below the threshold voltage (Vo_on-Vo_on_h) and Vo_De, and the charge pump module is directly used to power the secondary SR driver. In this way, dual power supply is achieved to ensure that the driving voltage of the secondary SR tube is sufficient. By switching between dual power supplies, the problem of low driving voltage of the secondary SR tube during overcurrent, short circuit, and startup is solved, thereby preventing damage to the power tube. The application scenarios are more open, and no specific primary side control IC is required. It is suitable for flyback, forward, LLC and other topologies, and is also suitable for digital control power supplies based on software control algorithms. The primary and secondary side drivers do not require a fixed dead time, and can directly open the secondary winding output through the primary side shutdown detection (the relevant detection can be described in subsequent inventions) to improve power efficiency.

[0078] In the aforementioned embodiments, a relatively simple, economical, and small circuit + power supply switching logic is used to realize the secondary side SR drive power supply, ensuring that its drive voltage is maintained above the SR turn-on voltage during startup and overcurrent short-circuit, fully turning on the SR and improving the power supply efficiency.

[0079] An embodiment of the present invention further provides a power supply device, comprising the rectifier circuit and a power supply as described in any one of the above embodiments, wherein the power supply is connected to the primary coil.

[0080] For specific examples in this embodiment, reference may be made to the examples described in the above embodiments and exemplary implementation modes, and this embodiment will not be described in detail herein.

[0081] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rectifier circuit, characterized in that: include: Primary coil; A secondary coil, the secondary coil cooperates with the primary coil; A first rectifier tube, wherein a first end of the first rectifier tube is connected to a first end of the secondary coil; an output capacitor, wherein a first end of the output capacitor is connected to a second end of the secondary coil, and a second end of the output capacitor is connected to a second end of the first rectifier tube; A first power supply unit, wherein a first input end of the first power supply unit is connected to a first end of the first rectifier tube, a second input end of the first power supply unit is connected to a first end of the output capacitor, and an output end of the first power supply unit is connected to a control end of the first rectifier tube; A second power supply unit, wherein an input end of the second power supply unit is connected to the first end of the output capacitor, and an output end of the second power supply unit is connected to the control end of the first rectifier tube; Wherein, when the output voltage of the output capacitor is less than a preset threshold voltage, the first power supply unit collects the electric energy in the secondary coil, and drives the first rectifier tube when the output voltage of the first power supply unit is a first voltage; when the output voltage of the output capacitor is greater than or equal to the preset threshold voltage, the second power supply unit drives the first rectifier tube; The first power supply unit includes: a first capacitor, a second capacitor, a first diode and a second diode, wherein the first end of the first capacitor is connected to the first end of the first rectifier tube, the second end of the first capacitor is connected to the first end of the first diode and the second end of the second diode, the second end of the first diode is connected to the first end of the second capacitor, the first end of the second diode is connected to the second end of the second capacitor, the first end of the second capacitor is connected to the control end of the first rectifier tube, and the second end of the second capacitor is connected to the first end of the output capacitor; The first diode only allows current to flow from the second end of the first capacitor to the first end of the second capacitor, and the second diode only allows current to flow from the first end of the output capacitor to the second end of the first capacitor.

2. The rectifier circuit according to claim 1, characterized in that: The first power supply unit further includes: a first resistor, and the first capacitor is connected to the first end of the secondary coil through the first resistor.

3. The rectifier circuit according to claim 1, characterized in that: The first power supply unit further includes: a third capacitor and a first zener diode, the first end of the third capacitor is connected to the first end of the second capacitor, the second end of the third capacitor is grounded, and the first zener diode is connected in parallel with the third capacitor.

4. The rectifier circuit according to claim 3, characterized in that: The first power supply unit further includes a fourth capacitor, a first end of the fourth capacitor is connected to the first end of the third capacitor, and a second end of the fourth capacitor is grounded.

5. The rectifier circuit according to claim 3, characterized in that: The first power supply unit further includes a second resistor, a first end of the first voltage regulator diode is connected to a first end of the third capacitor via the second resistor, and a second end of the first voltage regulator diode is grounded.

6. The rectifier circuit according to any one of claims 1 to 5, characterized in that: The rectifier circuit further includes: a switching unit, the output end of the first power supply unit is connected to the switching unit, the output end of the second power supply unit is connected to the switching unit, and the output end of the switching unit is connected to the control end of the first rectifier circuit.

7. The rectifier circuit according to claim 6, characterized in that: The second power supply unit includes: a first transistor and a second voltage regulator diode, wherein the first electrode of the first transistor and the first control electrode of the first transistor are both connected to the first end of the output capacitor, the second electrode of the first transistor is connected to the switching unit, the first end of the second voltage regulator diode is connected to the first control electrode, and the second end of the second voltage regulator diode is grounded; The first end of the second capacitor is connected to the switching unit, and the switching unit is also connected to the control end of the first rectifier tube. The switching unit is used to connect the first end of the second capacitor or the second electrode of the first transistor to the control end.

8. The rectifier circuit according to claim 7, characterized in that: The second power supply unit further includes a third resistor, and the first control electrode is connected to the first end of the output capacitor via the third resistor.

9. The rectifier circuit according to claim 6, characterized in that: The rectifier circuit also includes a drive control device, and the switching unit is connected to the control end of the first rectifier tube through the drive control device.

10. The rectifier circuit according to any one of claims 1 to 5, characterized in that: The rectifier circuit also includes a second rectifier tube. The second rectifier tube is connected to one end of the primary coil.

11. A power supply device, characterized in that: include: The rectifier circuit and power supply according to any one of claims 1 to 10, wherein the power supply is connected to the primary coil.

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