A rectifier bridge device based on active diode

Abstract

The present invention discloses a rectifier bridge device based on active diodes, including a combination logic control circuit, wherein the combination logic control circuit includes power supplies AC1, AC2, two groups of high-end drive switches with the same structure and two groups of low-end drive switches with the same structure; the two groups of high-end drive switches are PMOS supervisors V1, V4, and the two groups of low-end drive switches are NMOS supervisors V2, V3; the power supply AC1 is simultaneously connected to the drain of the PMOS supervisor V1 and the drain of the NMOS supervisor V3, the power supply AC2 is simultaneously connected to the drain of the PMOS supervisor V4 and the drain of the NMOS supervisor V2, the sources of the PMOS tubes V1 and V4 are both connected to the output power supply Vout, and the sources of the NMOS supervisors V2 and V3 are both grounded. Three types of rectifier bridge circuit devices are designed based on high-end active diodes and low-end active diodes, high-end active diodes and low-end NMOS tubes, and high-end PMOS tubes and low-end active diodes.

Description

Technical Field

[0001] The present invention relates to the technical field of rectifier bridges, and in particular to a rectifier bridge device based on active diodes. Background Art

[0002] Electronic circuits and devices generally require a stable DC power supply. A rectifier (bridge rectifier) ​​is a device that converts AC power to DC. Generally, AC power supplies require rectification, filtering, and conversion to DC before voltage conversion. The following are some of the most commonly used rectification schemes.

[0003] Ordinary diode solution: Due to its unidirectional conductivity, the diode is a natural Oring circuit. The most basic Oring circuit is to add a diode at the output end. Currently, rectifier bridges are mostly implemented using rectifier diodes and filter (energy storage) capacitors. Half-wave rectifier bridge circuits are often used to convert AC power into DC power. It is very simple to implement, but it wastes half a cycle of AC power. The utilization efficiency is about 50%, and the output voltage ripple is relatively large and the efficiency is low. The full-wave bridge rectifier circuit composed of four rectifier diodes makes full use of the entire cycle of AC power. It is a circuit that rectifies the entire cycle of AC power and makes full use of the positive and negative half cycles of AC power. The conversion efficiency is greatly improved compared to half-wave rectification, and the utilization efficiency is close to 100%. There is a filter capacitor at the output end. After passing through the filter capacitor, the output voltage ripple amplitude is very small, and the output voltage is smooth and stable. The rectifier diode conduction voltage drop V F =0.7V~2V (the greater the on-state current, the greater the voltage drop). The on-state voltage drop increases with the increase of input current. For example, the on-state current of rectifier diode S3MC is 0.1A, 1A, 10A, and 20A, and the corresponding on-state voltage drops are 0.74V, 0.85V, 1.16V, and 1.45V respectively. The conduction loss is 0.074W, 0.85W, 11.6W, and 29W respectively, which means that the greater the current, the greater the loss. The on-state voltage drop on the full-wave rectifier is the sum of the on-state voltage drops of the two series-connected diodes: approximately 2×V F The availability of inexpensive diodes makes half-wave and full-wave rectifiers widely used in some common circuits.

[0004] and Figure 1 Schematic diagram of a rectifier bridge device composed of common diodes: Although the four diodes are of the same model, their functions are different due to their different positions: diodes V1 and V4 are equivalent to high-end (high-side, high-side) diodes, and V2 and V3 are equivalent to low-end (low-side, low-side) diodes.

[0005] Schottky diode solution: Replacing rectifier diodes with Schottky diodes can reduce the forward voltage drop. Taking the Schottky diode SS54 as an example, the voltage drops corresponding to currents of 0.1A, 1A, 10A, and 20A are 0.3V, 0.4V, 0.85V, and 1.4V, respectively, and the losses are 0.03W, 0.4W, 8.5W, and 28W, respectively. As the current increases, the losses of the Schottky diode and the rectifier diode decrease. Replacing rectifier diodes with Schottky diodes can reduce the forward voltage drop and improve conversion efficiency and energy utilization. However, the Schottky diode has a large reverse current, low withstand voltage, and high cost, which limits its application range. The voltage drop of a full-wave rectifier bridge is the sum of two Schottky diodes in series: approximately 2×V F .

[0006] MOS tube solution: The MOS tube rectifier bridge in the two patents "POE rectifier bridge device based on MOS power tube, patent number: CN201820137186.9" and "A rectifier bridge device and rectifier device based on field effect tube, patent number: CN202222604210.4" is composed of two PMOS tubes and two NMOS tubes, which are mutually controlled (without additional MOS tube devices). The conduction voltage drop of the MOS tube is very small, and the voltage waveform (unfiltered) passing through the rectifier bridge is very good-looking, which is basically the same as its input voltage waveform, and is similar to an ordinary rectifier bridge. However, the filtering effect of loading the filter capacitor is very poor. When the author used Multisim software to simulate, the effect of using the filter capacitor was the same as that of not using the filter capacitor. Increasing the resistance of the load resistor or the capacity of the filter capacitor did not help. Specifically, the voltage of the filter capacitor was discharged and charged quickly (the rising waveform of the filter capacitor voltage means charging, and the falling waveform means discharging). The output voltage was not as smooth and stable as the rectifier bridge composed of diodes. After multiple simulations by the author, it was confirmed that there was a backflow (reverse) current in the drain-source channels of the two PMOS tubes. This is because the PMOS tube is still in the on state outside the conduction angle and a backflow current occurs (theoretically it should be in the off state); similarly, there is a backflow current when the two NMOS tubes at the low end are alternately turned on. This is why the filtering effect is very poor. Therefore, the circuit needs to be changed in design, such as using a charge pump to boost the gate of the PMOS tube to control it.

[0007] The MOS tube solution only uses 2 NMOS tubes + 2 PMOS tubes to replace 4 rectifier diodes. Although it solves the disadvantage of the large voltage drop caused by the diode, it does not have the function of curbing the backflow (reverse) current. When the output voltage is higher than the input voltage, due to the absence of the rectifier diode, the drain-source channel impedance of the MOS tube is lower, and a large amount of current will flow back from the output to the input, and only a small amount of current will flow to the load. The discharge speed of the filter capacitor is significantly accelerated, and the output voltage also drops rapidly. The size is basically the same as the input voltage, and the MOS tube rectifier bridge will also lose its meaning.

[0008] Active diode solution: The bias circuits of the high-side and low-side diode circuits described above act as comparators, acting as MOS transistor switches. Incorporating the concept of active diodes (also known as active diodes, see Torsten Lehmann and Yashodhan Moghe, “On-Chip Active Power Rectifiers for Biomedical Applications,” Proc. ISCAS, Vol. 1, pp. 732-735, 2005), the active diodes are constructed using a MOS transistor controlled by a comparator. The high-side active diode is constructed by replacing the bias circuit in the high-side ideal diode with a comparator, while the low-side active diode is constructed by replacing the bias circuit in the low-side ideal diode with a comparator.

[0009] A high-side active diode is constructed by replacing the bias circuit in a high-side ideal diode with a comparator, and a low-side active diode is constructed by replacing the bias circuit in a low-side ideal diode with a comparator. The operating principle of an active diode is as follows: when the input voltage is higher than the output voltage, the MOS transistor in the active diode turns on, resulting in a normal output voltage. When the output voltage exceeds the input voltage, the MOS transistor turns off, preventing current from flowing from the output to the input. Active diodes have unidirectional conduction characteristics, similar to ideal diodes. Current flows in a single direction through the active diode, resulting in a very low voltage drop.

[0010] The aforementioned rectification technologies all have certain drawbacks: pure diode rectifier bridges suffer from high voltage drops, and pure MOS tube rectifier bridges can suffer from backflow current. By leveraging the unidirectional conductivity of high-end active diodes and low-end active diodes, and leveraging their strengths to offset their weaknesses, it is necessary to develop a low-loss rectifier bridge device based on high-end active diodes, low-end active diodes, and MOS tubes. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a rectifier bridge device based on three types of devices: a high-end active diode and a low-end active diode, a high-end active diode and a low-end NMOS tube, and a high-end PMOS tube and a low-end active diode.

[0012] To solve the above technical problems, the present invention provides a technical solution: a rectifier bridge device based on active diodes, wherein the combination logic control circuit includes power supplies AC1 and AC2, two groups of high-side drive switches with the same structure, and two groups of low-side drive switches with the same structure;

[0013] The two sets of high-side drive switches are PMOS supervisors V1 and V4, and the two sets of low-side drive switches are NMOS supervisors V2 and V3;

[0014] The power supply AC1 is connected to the drain of the PMOS transistor V1 and the drain of the NMOS transistor V3 at the same time, the power supply AC2 is connected to the drain of the PMOS transistor V4 and the drain of the NMOS transistor V2 at the same time, the sources of the PMOS transistors V1 and V4 are connected to the output power supply Vout, and the sources of the NMOS transistors V2 and V3 are both grounded.

[0015] Preferably, the logic control circuit is provided with four groups of comparators, which are external comparators for controlling two groups of high-side drive switches and two groups of low-side drive switches.

[0016] Preferably, the external comparator is provided with four groups including comparators U1A, U2A, U1B, and U2B. The comparators U1A and U2A are respectively used to control the conduction and cutoff of the PMOS tubes V1 and V4, and the comparators U1B and U2B are respectively used to control the conduction and cutoff of the NMOS tubes V2 and V3.

[0017] The advantages of the present invention over the prior art are: The present invention provides three schemes: a high-end active diode and a low-end active diode, a high-end active diode and a low-end NMOS transistor, and a high-end PMOS transistor and a low-end active diode. The rectifier bridge device has the function of preventing backflow and can protect the previous stage circuit. The PMOS transistor and NMOS transistor have low on-resistance, low conduction loss, and are widely applicable. The combinational logic control circuit has a simple circuit and strong practicality.

[0018] For high-power power supply control, PMOS and NMOS tubes can be selected with an on-resistance of several milliohms between the drain and source. The voltage drop through the PMOS and NMOS tubes is very small and can be approximated as an ideal diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the schematic diagram of a rectifier bridge device composed of common diodes;

[0020] Figure 2 yes Figure 1 The current and conduction angle of the diode in the capacitor filter circuit;

[0021] Figure 3 This is a schematic diagram of a rectifier bridge device composed of a high-end active diode and a low-end active diode according to the present invention;

[0022] Figure 4 This is a schematic diagram of a rectifier bridge device based on a high-end active diode and a low-end NMOS tube of the present invention;

[0023] Figure 5 This is a schematic diagram of a rectifier bridge device based on a high-end PMOS tube and a low-end active diode of the present invention;

[0024] Figure 6 yes Figure 3 Circuit AC power supply simulation test diagram;

[0025] Figure 7 yes Figure 3 Circuit DC power supply simulation test diagram;

[0026] Figure 8 yes Figure 4 Circuit AC power supply simulation test diagram;

[0027] Figure 9 yes Figure 4 Circuit DC power supply simulation test diagram;

[0028] Figure 10 yes Figure 5 Circuit AC power supply simulation test diagram;

[0029] Figure 11 yes Figure 5 Circuit DC power supply simulation test diagram. DETAILED DESCRIPTION

[0030] The present invention will be described in further detail below with reference to the accompanying drawings.

[0031] Figure 1 The schematic diagram of a rectifier bridge device composed of common diodes: diodes V1 and V4 are equivalent to high-end diodes, and V2 and V3 are equivalent to low-end diodes.

[0032] Current mains electricity uses a 50Hz sine wave (AC power) with a period of T = 0.02s. One cycle is 360° in space, or 2π radians. The AC power changes once every 2π seconds, and this 2π is an electrical angle. This electrical angle is a temporal concept and is fundamentally different from an angle in space.

[0033] Before adding filter capacitors, Figure 1 The conduction angle θ of the diode in the rectifier circuit is π. After adding the filter capacitor, the pair of rectifier diodes will only be fully conductive when the capacitor is charged. Therefore, the conduction angle θ of each diode is less than π. The larger the product of the load RL and the filter capacitor C1, the better the filtering effect and the smaller the conduction angle θ. Generally speaking, RL×C1=(3~5)××T. Since the average output current increases after filtering, and the conduction angle of the diode decreases, a large inrush current will flow through the rectifier diode in a short period of time to charge the capacitor, which is very detrimental to the life of the diode. Therefore, a rectifier diode with a large conduction current capacity must be selected. Usually, its maximum rectifier average current I F Greater than 2 to 3 times the load current.

[0034] After adding filter capacitor C1, the diode rectifier circuit goes through 4 processes (6 states) in one cycle, such as Figure 2 As shown:

[0035] ①Process 1, conduction charging: When AC1 is in the positive half cycle and AC1-V F >Vout, capacitor C1 charges (duration is conduction angle θ), charging current is I D , a pair of rectifier diodes V1 and V2 are turned on, and another pair of rectifier diodes V4 and V3 are turned off, such as Figure 2 State A is shown.

[0036] ②Process 2, cut-off discharge: When AC1 is in the positive half cycle and AC1-V F ≤Vout, V2 tube is turned on, V1 tube, V4 tube, V3 tube are turned off, such as Figure 2 State B shows that the discharge current is i o ; Then AC2 is in the positive half cycle, when AC2-V F ≤Vout, V3 tube is turned on, V1 tube, V2 tube, V4 tube are turned off, such as Figure 2 State C; State B and State C are both cut-off states, capacitor C1 is discharged (total duration is π-θ), and the discharge current is i o .

[0037] ③Process 3, conduction charging: When AC2 is in the positive half cycle and AC2-V F > Vout, capacitor C1 charges (duration is conduction angle θ), a pair of rectifier diodes V4 and V3 are turned on, and another pair of rectifier diodes V1 and V2 are turned off. Figure 2 State D is shown.

[0038] ④Process 4, cut-off discharge: When AC2 is in the positive half cycle and AC2-V F ≤Vout, V3 tube is turned on, V1 tube, V2 tube, V4 tube are turned off, such as Figure 2 State E shows; then AC1 is in the positive half cycle, when AC1-V F ≤Vout, V2 tube is turned on, V1 tube, V4 tube, V3 tube are turned off, such as Figure 2 As shown in state F; both states E and F are cut-off states, and capacitor C1 is discharged (the total duration is π-θ).

[0039] ⑤ Cycle in sequence, the 4 processes (6 states) are specifically shown in Table 1, where the 4 diodes in state C and state E are in the same conduction state, and the 4 diodes in state B and state F are in the same conduction state.

[0040] Table 1 4 processes (6 states)

[0041] diode State A State B Status C Status D State E Status F V1 tube conduction Deadline Deadline Deadline Deadline Deadline V2 tube conduction conduction Deadline Deadline Deadline conduction V3 tube Deadline Deadline conduction conduction conduction Deadline V4 tube Deadline Deadline Deadline conduction Deadline Deadline

[0042] Figure 2 The upper middle part is the input AC power supply AC1, AC2, and the output voltage Vout waveform; the lower part is the rectifier diode conduction current i D Waveform, output current i o And conduction angle θ, cut-off region (π-θ).

[0043] According to the unidirectional conductive characteristics of the high-end active diode and the low-end active diode, two high-end active diodes are used to replace the diodes V1 and V4, and two low-end active diodes are used to replace the diodes V2 and V3, and a rectifier bridge device composed of high-end active diodes and low-end active diodes is obtained. Figure 3 shown.

[0044] For MOS transistor-based rectifier bridge circuits, the MOS transistors in the MOS transistor rectifier circuit can be controlled by an external control voltage, so that they only conduct when the AC power supply voltage rises to a certain control value. This means that under the condition that the original power supply remains unchanged, using different AC sine wave conduction angles can produce a varying DC power supply voltage. This controlled sine wave conduction angle is called the conduction angle.

[0045] Implementation Method 1

[0046] A rectifier bridge device based on a high-side active diode and a low-side active diode is shown in FIG. Figure 3 shown.

[0047] Figure 3 The PMOS tubes V1 and V4 and their peripheral circuits: the inverting end of the comparator U1A is connected to the drains of the PMOS tubes V1 and V3 and the power supply AC1 respectively, the inverting end of the comparator U2A is connected to the drains of the PMOS tubes V4 and V2 and the power supply AC2 respectively, the non-inverting ends of the comparators U1A and U2A are simultaneously connected to the sources of the PMOS tubes V1 and V4 and the output power supply Vout, the output ends of the comparators U1A and U2A are connected to the gates (control ends) of the PMOS tubes V1 and V4 respectively, the output ends of the comparators U1A, U2A, U1B, and U2B are OD circuit outputs (open drain outputs) and all require pull-up resistors, and the working power supplies of the comparators U1A and U2A are connected to Vout. NMOS tubes V2, V3 and their peripheral circuits: The non-inverting terminals of comparators U1B and U2B are connected to the sources of NMOS tubes V2 and V3 and GND at the same time, the inverting terminals of comparators U1B and U2B are connected to the drains of NMOS tubes V2 and V3 respectively, and the output terminals of comparators U1B and U2B are connected to the gates (control terminals) of NMOS tubes V2 and V3 respectively.

[0048] Depend on Figure 1 From the analysis of the diode rectifier circuit, we can see that Figure 3 The rectifier bridge device shown in the figure also goes through four processes (six states) in one cycle, as follows:

[0049] ① Process 1, conduction charging: When the AC power supply AC1 is in the positive half cycle and AC1>Vout, the comparator U1A outputs a low level, the gate of the PMOS tube V1 is low and the source is high (Vout=AC1-V F ), AC1-V F >-V TP (V F is the forward voltage drop of the PMOS diode, V TP is the turn-on threshold voltage of PMOS tubes V1 and V4), the drain-source channel of V1 tube is turned on; AC2 < GND, comparator U1B outputs a high level, the gate of NMOS tube V2 is high and the source is low, the drain-source channel of V2 tube is turned on; comparator U2A outputs a high level, comparator U2B outputs a low level, PMOS tube V4 and NMOS tube V3 are both cut off, corresponding Figure 2 State A. The charging path of capacitor C1 is transformer secondary positive terminal AC1 → PMOS transistor V1 → Vout → load RL → GND → NMOS transistor V2 → transformer secondary negative terminal AC2, and the total duration is conduction angle θ.

[0050] ②Process 2, cut-off discharge: When AC1 is in the positive half cycle and AC1-V F ≤Vout, comparator U1A outputs high level, V1 tube is cut off, V2 tube is turned on, V4 tube and V3 tube are cut off, corresponding Figure 2 In state B, the discharge path of capacitor C1 is Vout→load RL→GND→NMOS tube V2→transformer secondary negative terminal AC2; after a period of time, AC2 is in the positive half cycle, when AC2-V F When ≤Vout, comparator U2B outputs high level, V3 tube is turned on, comparator U1B outputs low level, V2 tube is turned off, V1 tube and V4 tube are turned off. Figure 2 In state C, the discharge path of capacitor C1 is Vout→load RL→GND→NMOS tube V3→transformer secondary negative terminal AC1; state B and state C are both cut-off states, and the total duration is π-θ.

[0051] ③Process 3, conduction charging: When the AC power supply AC2 is in the positive half cycle, AC2>Vout, the comparator U2A outputs a low level, the gate of the PMOS tube V4 is low and the source is high, that is, AC2-V F >-V TP , the drain-source channel of V4 tube is turned on; AC1<GND, comparator U2B outputs high level, the gate of NMOS tube V3 is high level, the source is low level, the drain-source channel of V3 tube is turned on; comparator U1A outputs high level, comparator U1B outputs low level, PMOS tube V1 and NMOS tube V2 are both cut off, corresponding Figure 2In the middle state D, the charging path of capacitor C1 is from the transformer secondary positive terminal AC2 → PMOS transistor V4 → Vout → load RL → GND → NMOS transistor V3 → transformer secondary negative terminal AC1.

[0052] ④ Process 4, cut-off discharge: When AC2 is in the positive half cycle, AC2≤Vout, comparator U2A outputs high level, V4 tube is cut off, V3 tube is turned on, V1 tube and V2 tube are cut off, corresponding to Figure 2 In the middle state E, the discharge path of capacitor C1 is Vout→load RL→GND→NMOS tube V3→transformer secondary negative terminal AC1; after a period of time, AC1 is in the positive half cycle. When AC1≤Vout, comparator U1A outputs a high level, V1 tube is cut off, V2 tube is turned on, V4 tube and V3 tube are cut off, corresponding to Figure 2 In state F, the discharge path of capacitor C1 is Vout→load RL→GND→NMOS tube V3→transformer secondary negative terminal AC2; state E and state F are both cut-off states, with a total duration of π-θ.

[0053] Implementation Method 2

[0054] The rectifier bridge device composed of high-end active diode and low-end NMOS tube is as follows: Figure 4 shown. Figure 4 The rectifier bridge device shown: When the AC power supply AC1 is in the positive half cycle or AC2 is in the positive half cycle, the current conduction path is the same as Figure 3 The working current conduction path of the circuit shown is consistent, and the analysis process refers to the first embodiment.

[0055] Implementation Method 3

[0056] The rectifier bridge device composed of high-end PMOS tube and low-end active diode is as follows: Figure 5 shown. Figure 5 The rectifier bridge device shown: When the AC power supply AC1 is in the positive half cycle or AC2 is in the positive half cycle, the current conduction path is the same as Figure 3 The working current conduction path of the circuit shown is consistent, and the analysis process refers to the first embodiment.

[0057] Implementation Method 1 Simulation

[0058] according to Figure 3 、 Figure 4 、 Figure 5 The schematic diagram was simulated using National Instruments' Multisim (version V14.0) software. The PMOS tube used was ON Semiconductor's NVTFS5124PLTAG, with a minimum on-threshold voltage of V TP(MIN) =-1.5V, maximum V TP(MAX)=-2.5V, typical value V not given TP , the on-state current can reach -6A, the on-state resistance R DS(ON) =0.26Ω(V GS =-10V), R DS(ON) =0.38Ω(V GS =-4.5V). The NMOS tube is made by NXP, model BSP030, with a minimum on-threshold voltage of V TN(MIN) =1V, maximum value V TN(MAX) =2.8V, typical value V is not given TN , the conduction current reaches 10A, the conduction resistance R DS(ON) =30mΩ(V GS =10V), R DS(ON) =50mΩ(V GS =4.5V). The comparator U1 (U2) is LM293P (with dual operational amplifiers), with an open-drain output (OD) and four 10kΩ pull-up resistors. The specific simulation test is as follows.

[0059] Figure 3 The transformer circuit shown has a 10:1 turns ratio between the primary and secondary windings, a 100Ω load impedance, and a 1000μF filter capacitor. Using a four-channel oscilloscope, Channel A (Channel_A) represents a 220V AC power source, Channel B (Channel_B) represents the transformer's secondary terminal AC1, Channel C (Channel_C) represents the transformer's secondary terminal AC2, and Channel D (Channel_D) represents the rectified voltage output, Vout. Figure 3 AC power simulation test such as Figure 6 Shown: From Figure 6 It can be seen that when the maximum voltage of the 220V AC power supply in the positive half cycle is 310.654V, AC1 = 31.026V, the rectified voltage output Vout = 30.437V, and the voltage difference is 31.026V-30.437V = 0.589V; when the maximum voltage of the 220V AC power supply in the negative half cycle is -309.898V, AC2 = 30.953V, the rectified voltage output Vout = 30.464V, and the conduction voltage drop is 30.953V-30.464V = 0.489V, which is less than the conduction voltage drop V of the diode. F .

[0060] If a 30V DC power supply is used and connected to the positive terminal AC1 and the negative terminal AC2, that is, AC1 is connected to the positive pole of the 30V power supply and AC2 is connected to the negative pole of the power supply, the DC power supply simulation test is as follows: Figure 7 As shown, the voltage is measured using an oscilloscope. Figure 7It can be seen that AC1=29.995V, the rectified voltage output Vout=29.918V, the PMOS tube V1 conduction voltage drop is 29.995V-29.919V=0.076V, and the corresponding conduction impedance is approximately R DS =257mΩ, which is consistent with the specification. The NMOS tube V2 has a forward voltage drop of 4.981mV. When AC2 is connected to the positive pole of the 30V power supply and AC1 is connected to the negative pole of the power supply, the forward voltage drop is still 29.995V-29.918V=0.076V. The forward voltage drop is very small, much lower than the forward voltage drop of the diode V F The power supply's positive output current is 303.575 mA, and the current flowing through the load is 299.19 mA. The bias circuit's current loss is approximately 303.575 mA - 299.19 mA = 4.385 mA, and the circuit's bias loss is 30 V × 4.385 mA = 131.55 mW.

[0061] Implementation Method 2 Simulation

[0062] Figure 4 AC power simulation test such as Figure 8 Shown: From Figure 8 It can be seen that when the maximum voltage of the 220V AC power supply in the positive half cycle is 310.432V, AC1 = 31.008V, the rectified voltage output Vout = 30.516V, and the voltage difference is 31.008V-30.516V = 0.492V; when the maximum voltage of the 220V AC power supply in the negative half cycle is -310.717V, AC2 = 31.038V, the rectified voltage output Vout = 30.201V, and the conduction voltage drop is 31.038V-30.201V = 0.837V, which is slightly larger than the conduction voltage drop V of the diode. F .

[0063] If a 30V DC power supply is used and connected to the positive terminal AC1 and the negative terminal AC2, that is, AC1 is connected to the positive pole of the 30V power supply and AC2 is connected to the negative pole of the power supply, the DC power supply simulation test is as follows: Figure 9 As shown, the voltage is measured using an oscilloscope. Figure 9 It can be seen that AC1=29.995V, the rectified voltage output Vout=29.919V, the PMOS tube V1 conduction voltage drop is 29.995V-29.919V=0.076V, and the corresponding conduction impedance is approximately R DS =254mΩ, which is consistent with the specification. The NMOS tube V2 has a forward voltage drop of 4.976mV. When AC2 is connected to the positive pole of the 30V power supply and AC1 is connected to the negative pole of the power supply, the forward voltage drop is still 29.995V-29.919V=0.076V. The forward voltage drop is very small, much lower than the forward voltage drop of the diode V FThe positive output current of the power supply is 302.831mA, and the current flowing through the load is 299.192mA. The bias circuit current loss is approximately 302.831mA - 299.178mA = 3.639mA, and the bias loss of the circuit is 30V × 3.639mA = 109.17mW.

[0064] Implementation Method 3 Simulation

[0065] Figure 5 AC power simulation test such as Figure 10 Shown: From Figure 10 It can be seen that when the maximum voltage of the 220V AC power supply in the positive half cycle is 310.048V, AC1 = 30.972V, the rectified voltage output Vout = 30.474V, and the voltage difference is 30.972V-30.474V = 0.498V; when the maximum voltage of the 220V AC power supply in the negative half cycle is -310.540V, AC2 = 31.021V, the rectified voltage output Vout = 30.511V, and the conduction voltage drop is 31.021V-30.511V = 0.510V, which is less than the conduction voltage drop V of the diode. F .

[0066] If a 30V DC power supply is used and connected to the positive terminal AC1 and the negative terminal AC2, that is, AC1 is connected to the positive pole of the 30V power supply and AC2 is connected to the negative pole of the power supply, the DC power supply simulation test is as follows: Figure 11 As shown, the voltage is measured using an oscilloscope. Figure 11 It can be seen that AC1=29.995V, the rectified voltage output Vout=29.920V, the PMOS tube V1 conduction voltage drop is 29.995V-29.920V=0.075V, and the corresponding conduction impedance is approximately R DS =250mΩ, consistent with the specification, the NMOS tube V2 conduction voltage drop is 4.927mV; when AC2 is connected to the positive pole of the 30V power supply and AC1 is connected to the negative pole of the power supply, the conduction voltage drop is still 29.995V-29.920V=0.075V, which is very small and much lower than the conduction voltage drop of the diode V F The power supply's positive output current is 300.591 mA, and the current flowing through the load is 299.198 mA. The bias circuit's current loss is approximately 300.591 mA - 299.198 mA = 1.393 mA, and the circuit's bias loss is 30 V × 1.393 mA = 41.790 mW.

[0067] Simulation comparison of the three implementations: Under the same power supply and load conditions, the conduction voltage drops of the two are not much different, but implementation method three has lower loss, followed by implementation method two. The rectifier bridge circuit formed by implementation method three is preferred.

[0068] The beneficial effects of the present invention are: Compared with the traditional pure diode rectifier bridge, the voltage drop is larger (2×V F ), pure MOS tube rectifier bridge has the problem of backflow current, weighing the pros and cons of diodes and MOS tubes, combining the unidirectional conductivity of diodes and the low on-resistance R of MOS tubes DS Characteristics, leveraging strengths to offset weaknesses and achieve complementary advantages: The three solutions mentioned above utilize three types of rectifier bridge devices: a high-end active diode and a low-end active diode, a high-end active diode and a low-end NMOS transistor, and a high-end PMOS transistor and a low-end active diode. These devices have a backflow prevention function, protecting the preceding circuit. PMOS and NMOS transistors have low on-resistance, low conduction losses, and are widely used. Combinatorial logic control circuits are simple and highly practical. For high-power power supply control, PMOS and NMOS transistors can be selected with an on-resistance of several milliohms between the drain and source and a high current flow rate. The voltage drop across the PMOS and NMOS transistors is very small, and they can be approximated as an ideal diode. MOS transistors have low on-resistance, are inexpensive, have a wide selection, and offer a simple circuit and low cost.

[0069] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A rectifier bridge device based on an active diode, characterized in that: The combinational logic control circuit includes power supplies AC1, AC2, two groups of high-end drive switches with the same structure, and two groups of low-end drive switches with the same structure; The two sets of high-side drive switches are PMOS supervisors V1 and V4, and the two sets of low-side drive switches are NMOS supervisors V2 and V3; The power supply AC1 is connected to the drain of the PMOS tube V1 and the drain of the NMOS tube V3 at the same time, the power supply AC2 is connected to the drain of the PMOS tube V4 and the drain of the NMOS tube V2 at the same time, the sources of the PMOS tubes V1 and V4 are connected to the output power supply Vout, and the sources of the NMOS tubes V2 and V3 are both grounded.

2. The active diode-based rectifier bridge device according to claim 1, characterized in that: The logic control circuit is provided with four groups of comparators, which are used to control the external comparators of two groups of high-end drive switches and two groups of low-end drive switches.

3. The active diode-based rectifier bridge device according to claim 2, characterized in that: The external comparator is provided with four groups including comparators U1A, U2A, U1B, and U2B. The comparators U1A and U2A are respectively used to control the on and off of the PMOS tubes V1 and V4, and the comparators U1B and U2B are respectively used to control the on and off of the NMOS tubes V2 and V3.

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