A low-loss three-phase rectifier bridge circuit

Abstract

The present invention discloses a low-loss three-phase rectifier bridge circuit, including a combination logic control circuit, a low-end tube as a diode, and a high-end tube as a PMOS type high-end ideal diode, a PNP type high-end ideal diode, and a PMOS type high-end active diode. A total of three low-loss three-phase rectifier bridge circuits are designed: utilizing the single-phase conductive characteristics of the high-end ideal (active) diode, the rectifier bridge circuit automatically switches, rectifies, and filters the three-phase AC power supply into direct current without the need for external device control. The switching circuit has a low conduction voltage drop, which is lower than the voltage drop loss of a pure diode rectifier bridge; it has an anti-backflow function, which solves the problem of backflow current in a pure MOS tube rectifier bridge; under the same conditions, the PMOS tube has low conduction impedance, low price, rich selection, simple circuit and very low cost advantages.

Description

Technical Field

[0001] The invention relates to the technical field of rectifier bridges, and in particular to a low-loss three-phase rectifier bridge circuit. Background Art

[0002] The ripple coefficient of single-phase half-wave rectification is π / 2≈1.57, and the ripple coefficient of single-phase bridge rectification is 2 / 3≈0.67. According to Fourier analysis, the fundamental frequency of the single-phase bridge rectifier circuit is twice that of the single-phase half-wave rectification. Compared with the half-wave rectification circuit, the pulsating voltage output by the bridge rectifier circuit is much reduced. To some extent, it can be considered that the fundamental frequency of the three-phase bridge rectifier circuit is three times that of the single-phase bridge rectifier. In practical applications, when the output power of the rectifier circuit is large and the pulsating (ripple) voltage is required to be small, a three-phase rectifier circuit is required. The composition principles and methods of the three-phase rectifier circuit are the same as those of the single-phase rectifier circuit.

[0003] In order to maximize the rectification power, a three-phase full-bridge rectifier circuit is generally used. Its circuit topology is widely used in high-power conversion systems such as industrial frequency conversion, diesel generators, and internal combustion locomotives. The more commonly used rectification schemes are as follows.

[0004] Diode solution: The three-phase bridge fully controlled rectifier circuit is a very simple circuit topology, such as Figure 1 As shown in the figure, the rectifier circuit consists of three diodes with a common cathode (V1, V4, V6, equivalent to a high-end diode) and three diodes with a common anode (V2, V3, V5, equivalent to a low-end diode). The main characteristic of the diode is that it has unidirectional conductivity. When the anode voltage is greater than the cathode voltage, it is turned on (the turn-on voltage varies from 0.7V to 2V). For the three diodes with a common cathode, the diode with the largest AC voltage connected to the anode is turned on first; and for the three diodes with a common anode, the diode with the smallest AC voltage connected to the cathode is turned on first. The disadvantage is that there are two diodes in the loop, and the voltage drop loss reduces the efficiency. For example, when the load current is large, a large amount of power is dissipated, which requires heat dissipation design (such as heat sink) or active cooling solution (such as air cooling) in the structure, which indirectly leads to the complexity of the design and the increase of the structure size, as well as the increase of the cost.

[0005] Ideal diode bridge controller solution: Linear Technology has introduced a low-loss three-phase ideal diode bridge rectifier solution. The LT4320 integrates charge pump boost technology, which can control the opening and closing of NMOS tubes, thereby replacing the larger and more expensive PMOS tube switches. The evaluation board DC2465 reference design uses three LT4320 ideal diode bridge controllers and six low-loss NMOS tubes to replace the six diodes of the traditional three-phase rectifier. Compared with the two diode voltage drops inherent in the traditional three-phase diode rectifier bridge, this solution can greatly reduce the voltage drop and power loss. The additional margin brought by this design is beneficial to low-voltage applications, which can save the physical space of the product (and greatly reduce the PCB board area) and loss. The only drawback is that the DC2465 evaluation board is expensive, costing more than $100 each. The price of LT4320 in a well-known domestic electronic device mall is close to 80 yuan per piece (the minimum order quantity is 30 pieces, including tax). The three-phase NMOS tube rectifier bridge uses three LT4320 ideal diode bridge controllers, and the price is close to 240 yuan, which is very expensive and ordinary users can hardly afford it.

[0006] MOS tube solution: The MOS tube rectifier bridge in the two patents "POE three-phase rectifier bridge circuit based on MOS power tube, patent number: CN201820137186.9" and "A three-phase rectifier bridge circuit 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 the loaded filter capacitor is very poor. When the author uses Multisim software to simulate, the voltage waveform of the filter capacitor is the same as that of the filter capacitor. Changing the load resistance or the filter capacitor capacity is of no avail. Specifically, the voltage of the filter capacitor discharges and charges quickly (the rising curve of the filter capacitor voltage waveform means charging, and the falling curve means discharging). The output voltage is not as smooth and stable as the rectifier bridge composed of diodes. After multiple simulations by the author, it is confirmed that there is a backflow (reverse) current in the drain-source channels of the two PMOS tubes. Similarly, there is a backflow current when the two NMOS tubes at the low end are alternately turned on. This is the reason for the very poor filtering effect. Therefore, the circuit needs to be designed differently, such as using a charge pump to boost the gate of the NMOS 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 large voltage drop caused by diodes, it does not have the function of curbing backflow (reverse) current. When the output voltage is higher than the input voltage, due to the absence of rectifier diodes, the drain-source channel impedance of the MOS tube is lower, 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, which is basically the same as the input voltage. The MOS tube rectifier bridge will also lose its meaning.

[0008] The prior art patent (an ultra-low loss ideal diode, patent number: CN201821304820.X) belongs to a high-end ideal diode, including a logic control circuit and a PMOS main tube. The logic control circuit has two independent PMOS auxiliary tubes (auxiliary tubes) or a PMOS pair of tubes (auxiliary tubes) with the same parameters and packaged together, and two resistors to form a comparator circuit to control the conduction and cutoff of the PMOS main tube: when the input voltage (such as AC1) is not less than the output voltage Vout, the PMOS main tube is turned on; otherwise (such as AC1 is greater than the output voltage Vout), the PMOS main tube is cut off to prevent the output current from flowing back to the input end, thereby protecting the input end power supply circuit, which is equivalent to a high-end ideal (power) diode.

[0009] However, the current rectification technology solutions realized by diodes all have certain shortcomings: the voltage drop of the diode rectifier bridge is large, the NMOS tube + PMOS tube rectifier bridge has the problem of backflow current, and the LT4320 (integrated charge pump boost technology) + NMOS tube has excellent performance but is too expensive. Combining the characteristics of the above solutions, it is necessary to develop a three-phase rectifier bridge circuit based on MOS tubes and diodes with low loss, cheaper price and richer selection. Summary of the invention

[0010] The technical problem to be solved by the present invention is to overcome the above technical defects and provide a three-phase rectifier bridge circuit based on MOS tubes and diodes.

[0011] In order to solve the above technical problems, the technical solution provided by the present invention is: a low-loss three-phase rectifier bridge circuit, including a combinational logic control circuit, the combinational logic control circuit includes a three-phase power supply, three groups of high-end diodes, three groups of low-end diodes and a filter capacitor, the high-end diode includes a main circuit and an auxiliary circuit for controlling the conduction and cutoff of the main circuit, the three groups of high-end diodes have the same circuit structure and are respectively connected to the AC1, AC2 and AC3 terminals of the three-phase power supply.

[0012] Preferably, the main conductor of the high-end diode is a PMOS main conductor, and the auxiliary circuit is a comparator, including any one of a voltage comparator, a PMOS pair of transistors or a PNP pair of transistors;

[0013] The output end of the comparator is connected to the gate of the PMOS tube. When the voltage of the input end of the comparator is higher than that of the output end, the PMOS tube of the high-end diode is turned on, otherwise the PMOS tube is turned off.

[0014] Preferably, the auxiliary circuit is a PMOS pair connected to the source and drain ends of the PMOS main tube;

[0015] The source of the PMOS pair is connected to the drain and source of the PMOS main tube respectively, the drain of the PMOS pair is connected to drain resistors R1A and R1B respectively, the gate of the front-end PMOS tube is connected to the drain resistor R1A, and the gate of the PMOS main tube is connected to the drain resistor R1B.

[0016] Preferably, the auxiliary circuit is a PNP pair of transistors connected to the source and drain ends of the PMOS tube;

[0017] The emitters of the PNP pair are connected to the drain and source of the PMOS main tube respectively, the collectors of the PNP pair are connected to the collector resistors R1A and R1B respectively, the base of the front-end PNP tube is connected to the collector resistor R1A, and the gate of the PMOS main tube is connected to the collector resistor R1B.

[0018] Preferably, the auxiliary circuit is a voltage comparator connected to the source terminal and the drain terminal of the PMOS tube;

[0019] The in-phase terminal and the inverting terminal of the voltage comparator are respectively connected to the drain and source of the PMOS tube, and the gate of the PMOS tube is connected to the output terminal of the voltage comparator and connected to the rectifier power supply output terminal Vout through a pull-up resistor.

[0020] Compared with the prior art, the advantages of the present invention are: the diode has the function of preventing backflow and can protect the previous circuit; the use of MOS tubes and ideal diodes has lower conduction voltage drop and loss; the combination logic control circuit has a simple circuit, many applications, many requirements, many models, low price and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the schematic diagram of a three-phase rectifier bridge circuit composed of common diodes;

[0022] Figure 2 The present invention is a schematic diagram of a three-phase rectifier bridge circuit composed of a PMOS type high-end ideal diode and a low-end diode;

[0023] Figure 3 The present invention is a schematic diagram of a three-phase rectifier bridge circuit composed of a PNP type high-end ideal diode and a low-end diode;

[0024] Figure 4The present invention is a schematic diagram of a three-phase rectifier bridge circuit composed of a PMOS type high-end active diode and a low-end diode;

[0025] Figure 5 yes Figure 2 Circuit three-phase rectification simulation test diagram;

[0026] Figure 6 yes Figure 3 Circuit three-phase rectification simulation test diagram;

[0027] Figure 7 yes Figure 4 Circuit three-phase rectification simulation test diagram. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0029] Replacement with high-side ideal diode Figure 1 The diodes V1, V4, and V6 in Figure 2 To distinguish high-end ideal diodes, since the two auxiliary tubes are PMOS tube pairs, they are called PMOS type high-end ideal diodes; if the two auxiliary tubes are PNP tube pairs, they are called PNP type high-end ideal diodes.

[0030] like Figure 2 As shown, three groups of PMOS high-end ideal diodes are used to replace the three diodes (V1, V4, V6) with a common cathode, including low-end diodes V2, V3, V5, PMOS main tubes V1, V4, V6, PMOS auxiliary tubes V1A, V1B, V4A, V4B, V6A, V6B, drain resistors R1A, R1B, R4A, R4B, R6A, R6B, filter (energy storage) capacitor C1, etc., among which: PMOS main tube V1, PMOS auxiliary tubes V1A, V1B and drain resistors R1A, R1B constitute a PMOS high-end ideal diode (equivalent to Figure 1 The diode V1 in the PMOS main tube V4, the PMOS auxiliary tubes V4A, V4B and the drain resistors R4A, R4B constitute a PMOS type high-end ideal diode (equivalent to Figure 1 The diode V4 in the middle); the PMOS main tube V6, the PMOS auxiliary tubes V6A, V6B and the drain resistors R6A, R6B constitute a PMOS type high-end ideal diode (equivalent to Figure 1 diode V6 in the circuit).

[0031] Three groups of PMOS high-end ideal diodes are connected between the three-phase power supply AC1, AC2, AC3 and the load respectively. Figure 2 As shown, the unidirectional conductive characteristics of the PMOS type high-side ideal diode are used to control the conduction and cutoff of the high-side PMOS tubes V1, V4, and V6.

[0032] Figure 2 Current path: In the positive half cycle of alternating current AC1, when voltage AC1>AC2>AC3, AC1>VF-VTP (VF is the conduction voltage drop of the PMOS tube body diode, and VTP is the conduction threshold voltage of the PMOS tube), the drain-source channel of the PMOS tube V1 is turned on, and the diode V5 is turned on first. The current conduction path is AC1 positive terminal→PMOS tube V1→Vout→load RL→diode V5→AC3 negative terminal; when voltage AC1>AC3>AC2, diode V3 is turned on, and the current conduction path is AC1 positive terminal→PMOS tube V1→Vout→load RL→diode V3→AC2 negative terminal.

[0033] As a high-end ideal diode (load switch), the PMOS type high-end ideal diode has a small voltage drop after rectification and filtering, and a very smooth and stable voltage waveform.

[0034] Technical solution 2: A three-phase rectifier bridge circuit composed of a PNP type high-end ideal diode and a low-end diode.

[0035] PNP tubes and PMOS tubes are interchangeable, but the bias circuits are slightly different. As long as the bias circuit design is reasonable, they can work. Based on the above replacement ideas, on the basis of technical solution one, PNP auxiliary tubes can be used to replace PMOS auxiliary tubes to obtain a high-end ideal diode (PNP type high-end ideal diode) based on PMOS main tube + PNP pair tubes and a rectifier bridge device composed of diodes to achieve technical solution two.

[0036] Use PNP type high side ideal diode to replace Figure 1 The diodes V1, V4, and V6 in the figure are three groups of PNP high-end ideal diodes connected between the three-phase power supply AC1, AC2, and AC3 and the load, respectively. Figure 3 As shown, the unidirectional conductive characteristic of the PNP type high-side ideal diode is used to control the conduction and cutoff of the high-side PMOS tubes V1, V4, and V6.

[0037] Theoretical analysis refers to Technical Solution 1.

[0038] Technical solution three: A three-phase rectifier bridge circuit composed of a PMOS type high-end active diode and a low-end diode.

[0039] Active diode: Use a comparator to replace the bias circuit in the PMOS type high-end ideal diode to form a "PMOS type high-end active diode". Working principle of active diode: When the input voltage is higher than the output voltage, the PMOS tube of the active diode is turned on, and the output voltage output is normal. When the output voltage is greater than the input voltage, the PMOS tube is turned off to prevent the directional current from flowing from the output to the input. The active diode has a unidirectional conductive characteristic, which is similar to an ideal diode.

[0040] Based on the three-phase rectifier bridge circuit composed of PMOS type high-end active diodes and low-end diodes, three sets of PMOS type high-end active diodes are used to replace Figure 1 The diodes V1, V4, and V6 in the figure are three groups of PMOS high-side active diodes connected between the three-phase power supply AC1, AC2, and AC3 and the load, respectively. Figure 4 As shown, the unidirectional conductive characteristics of the PMOS type high-side active diode are used to control the conduction and cutoff of the high-side PMOS tubes V1, V4, and V6.

[0041] Theoretical analysis refers to Technical Solution 1.

[0042] Among the above three solutions: when the low-end tube is a diode, the high-end tube can be a PMOS-type high-end ideal diode, a PNP-type high-end ideal diode, or a PMOS-type high-end active diode. If the high-end tube is a single PMOS tube, there will be backflow current, so it will not be adopted. When the high-end tube is a diode, and the low-end tube is an NMOS tube, an NMOS-type low-end ideal diode, an NPN-type low-end ideal diode, or an NMOS-type low-end active diode, since the three-phase rectifier bridge control circuit is relatively complex, it is difficult to achieve mutual control using a simple high-end ideal diode, and there will be backflow current, so it will not be adopted; different combinations of high-end tubes (same type, same component model) and low-end tubes (same type, same component model) are shown in Table 1 below, and the circuit is detailed in Table 1. Figure 2 to Figure 4 .

[0043] Table 1 Rectifier bridge combination consisting of high-end tubes and low-end tubes

[0044]

[0045] Implementation Method 1

[0046] Figure 1 The schematic diagram of a three-phase rectifier bridge circuit composed of common diodes: diodes V1, V4, and V6 are equivalent to high-end diodes, and V2, V3, and V5 are equivalent to low-end diodes.

[0047] According to the single-phase conduction characteristics of the PMOS type high-end ideal diode, three groups of PMOS type high-end ideal diodes are used to replace the three diodes (V1, V4, V6) with a common cathode to obtain a three-phase rectifier bridge circuit based on the PMOS type high-end ideal diode and the low-end diode, as shown in Figure 2 shown.

[0048] Figure 2Circuit: including low-end diodes V2, V3, V5, PMOS tubes V1, V4, V6, PMOS auxiliary tubes V1A, V1B, V4A, V4B, V6A, V6B, drain resistors R1A, R1B, R4A, R4B, R6A, R6B, filter (energy storage) capacitor C1, etc., among which: PMOS tube V1, PMOS auxiliary tubes V1A, V1B and drain resistors R1A, R1B constitute a PMOS type high-end ideal diode (equivalent to Figure 1 The diode V1 in the PMOS tube V4, the PMOS auxiliary tubes V4A, V4B and the drain resistors R4A, R4B constitute a PMOS type high-end ideal diode (equivalent to Figure 1 The diode V4 in the PMOS tube V6, the PMOS auxiliary tubes V6A, V6B and the drain resistors R6A, R6B constitute a PMOS type high-end ideal diode (equivalent to Figure 1 diode V6 in the circuit).

[0049] Three groups of PMOS type high-end ideal diodes are respectively connected between the three-phase power supply AC1, AC2, AC3 and the load, and the unidirectional conductive characteristics of the PMOS type high-end ideal diodes are used to control the conduction and cutoff of the high-end PMOS tubes V1, V4, and V6.

[0050] Figure 2 Current path: In the positive half cycle of alternating current AC1, when voltage AC1>AC2>AC3, AC1>VF-VTP, the drain-source channel of PMOS tube V1 is turned on, diode V5 is turned on first, and the current conduction path is AC1 positive terminal→PMOS tube V1→Vout→load RL→diode V5→AC3 negative terminal; when voltage AC1>AC3>AC2, diode V3 is turned on, and the current conduction path is AC1 positive terminal→PMOS tube V1→Vout→load RL→diode V3→AC2 negative terminal.

[0051] The PMOS type high-end ideal diode is used as a high-end load switch. After rectification and filtering, the voltage drop is small, and the voltage waveform is very smooth and stable. In addition, the PNP auxiliary tube can be used to replace the PMOS auxiliary tube to obtain another high-end ideal diode, which will not be described in detail.

[0052] Implementation Method 2

[0053] According to the first embodiment, the PNP tube and the PMOS tube can be interchanged, but the bias circuit is slightly different. As long as the bias circuit is designed reasonably, they can work. Based on the above replacement ideas, on the basis of technical solution one, the PNP auxiliary tube can be used to replace the PMOS auxiliary tube to obtain a high-end ideal diode based on the PMOS main tube + PNP pair tube (called a PNP type high-end ideal diode) and a rectifier bridge device composed of a diode.

[0054] Use PNP type high side ideal diode to replace Figure 1 The diodes V1, V4, and V6 in Figure 3 As shown, three groups of PMOS type high-end ideal diodes are respectively connected between the three-phase power supply AC1, AC2, AC3 and the load, and the unidirectional conductive characteristics of the PMOS type high-end ideal diodes are used to control the conduction and cutoff of the high-end PMOS tubes V1, V4, and V6.

[0055] Implementation Method 3

[0056] Consistent with the first implementation mode: a three-phase rectifier bridge circuit composed of a PMOS type high-side active diode and a low-side diode.

[0057] Active diode: Use a comparator to replace the bias circuit in the PMOS type high-end ideal diode to form a "PMOS type high-end active diode". Working principle of active diode: When the input voltage is higher than the output voltage, the PMOS tube of the active diode is turned on, and the output voltage output is normal. When the output voltage is greater than the input voltage, the PMOS tube is turned off to prevent the directional current from flowing from the output to the input. The active diode has a unidirectional conductive characteristic, which is similar to an ideal diode.

[0058] Based on the three-phase rectifier bridge circuit composed of PMOS type high-end active diode and low-end diode, the PMOS type high-end active diode is used to replace Figure 1 The diodes V1, V4, and V6 in Figure 4 As shown, three groups of PMOS type high-side active diodes are respectively connected between the three-phase power supply AC1, AC2, AC3 and the load, and the unidirectional conductive characteristics of the PMOS type high-side active diodes are used to control the conduction and cutoff of the high-side PMOS tubes V1, V4, and V6.

[0059] The current paths of the second and third embodiments refer to the first embodiment.

[0060] according to Figure 2 , Figure 3 , Figure 4The circuit three-phase rectifier bridge schematic diagram is simulated and tested using the simulation software Multisim (version V14.0) of National Instruments. The PMOS tube is selected from ON Semiconductor, model NVTFS5124PLTAG, the minimum threshold voltage VTP (MIN) = -1.5V, the maximum value VTP (MAX) = -2.5V, and the typical value VTP is not given. The on-current can reach -6A, and the on-resistance RDS (ON) = 0.26Ω (VGS = -10V), RDS (ON) = 0.38Ω (VGS = -4.5V). The diode is selected from Motorola, model MBR340M, with an on-current of 3A (corresponding on-voltage drop of 0.6V) and a withstand voltage of 40V. The specific simulation test is as follows.

[0061] Bridge Rectifier Circuit Simulation

[0062] Figure 1 The three-phase rectifier bridge diodes in the simulation are from Generic, model 1N4007. The three-phase AC output is 22Vrms, and the phase difference is 120°. The transformer can be omitted during simulation. The load impedance is 100Ω and the filter capacitor is 1000μF. Using a four-channel oscilloscope, Channel A (Channel_A) is 22Vrms AC1, Channel B (Channel_B) is 22Vrms AC2, Channel C (Channel_C) is 22Vrms AC3, and Channel D (Channel_D) is the rectified voltage Vout. When the 22Vrms three-phase alternating current has the maximum voltage in the positive half cycle, the corresponding conduction voltage drops of the three-phase rectifier diodes V1, V4, and V6 are 30.630V-30.474V=0.156V, 31.052V-29.977V=1.075V, and 30.827V-29.557V=1.27V respectively.

[0063] Implementation Method 1 Simulation

[0064] The simulation test of the three-phase rectifier bridge circuit composed of PMOS type high-end ideal diode and low-end diode is as follows: Figure 5 As shown in the figure, the resistance of the six bias resistors (R1A, R1B, R4A, R4B, R6A, R6B) are all 1MΩ. Figure 5It can be seen that when the 22Vrms three-phase AC power is the maximum voltage in the positive half cycle, the corresponding conduction voltage drops of the PMOS high-end ideal diodes V1, V4, and V6 are 31.025V-30.503V=0.522V, 31.054V-30.317V=0.737V, and 31.002V-30.202V=0.800V (not shown in the figure), respectively. The corresponding conduction voltage drops are not much different from the conduction voltage drop VF of the diode.

[0065] Implementation Method 2 Simulation

[0066] The simulation test of the three-phase rectifier bridge composed of PNP type high-end ideal diode and low-end diode is as follows: Figure 6 As shown in the figure, the resistance of the six bias resistors (R1A, R1B, R4A, R4B, R6A, R6B) are all 1MΩ. Figure 6 It can be seen that when the 22Vrms three-phase AC power is the maximum voltage of the positive half-cycle, the corresponding conduction voltage drops of the PNP high-end ideal diodes V1, V4, and V6 are 30.520V-30.384V=0.136V, 30.921V-30.307V=0.614V, and 31.061V-30.503V=0.558V (not shown in the figure), and the corresponding average conduction voltage drop is less than the conduction voltage drop VF of the diode.

[0067] Implementation Method 3 Simulation

[0068] The simulation test of the three-phase rectifier bridge composed of PMOS type high-end active diode and low-end diode is as follows: Figure 7 As shown, the resistance of the three pull-up resistors (R1, R4, R6) is 10kΩ. Figure 7 It can be seen that when the 22Vrms three-phase AC power is the maximum voltage in the positive half cycle, the corresponding conduction voltage drops of the PMOS high-side active diodes V1, V4, and V6 are 30.828V-30.234V=0.594V, 30.676V-30.090V=0.586V, and 31.057V-30.509V=0.548V (not shown in the figure), respectively. The corresponding conduction voltage drops are less than the conduction voltage drop VF of the diode.

[0069] Simulation comparison of three implementation methods: Under the same power supply and load conditions, the three are not much different, which is better than the three-phase rectifier bridge composed of pure diodes. In terms of static power consumption, the three-phase rectifier bridge circuit composed of PMOS type high-end ideal diodes and low-end diodes is preferred.

[0070] The beneficial effects of the present invention are as follows: compared with the larger voltage drop (2×VF) of the traditional pure diode rectifier bridge and the backflow current problem of the pure MOS tube rectifier bridge, a compromise design is made for the diode and the MOS tube, and the unidirectional conductivity of the diode and the low on-resistance RDS characteristic of the MOS tube are combined to complement each other's advantages: the voltage drop of the circuit is about VF+RDS×ID (when the current ID is small, the second item can be omitted), which is smaller than the voltage drop (2×VF) of the pure diode rectifier bridge; the circuit has a backflow prevention function, which can solve the backflow current problem of the pure MOS tube rectifier bridge; the MOS tube has the advantages of low on-resistance, low price, rich selection, simple circuit and very low cost.

[0071] The present invention and its embodiments are described above, and such 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 ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A low-loss three-phase rectifier bridge circuit, including a combinational logic control circuit, characterized in that: The combinational logic control circuit includes a three-phase power supply, three groups of high-end diodes, three groups of low-end diodes and a filter capacitor. The high-end diode includes a main circuit and an auxiliary circuit for controlling the conduction and cutoff of the main circuit. The three groups of high-end diodes have the same circuit structure and are respectively connected to the AC1, AC2 and AC3 terminals of the three-phase power supply.

2. A low-loss three-phase rectifier bridge circuit according to claim 1, characterized in that: The main conductor of the high-end diode is a PMOS main conductor, and the auxiliary circuit is a comparator, including any one of a voltage comparator, a PMOS pair of transistors or a PNP pair of transistors; The output end of the comparator is connected to the gate of the PMOS tube. When the voltage of the input end of the comparator is higher than that of the output end, the PMOS tube of the high-end diode is turned on, otherwise the PMOS tube is turned off.

3. A low-loss three-phase rectifier bridge circuit according to claim 2, characterized in that: The auxiliary circuit is a PMOS pair connected to the source and drain ends of the PMOS main tube; The source of the PMOS pair is connected to the drain and source of the PMOS main tube respectively, the drain of the PMOS pair is connected to drain resistors R1A and R1B respectively, the gate of the front-end PMOS tube is connected to the drain resistor R1A, and the gate of the PMOS main tube is connected to the drain resistor R1B.

4. A low-loss three-phase rectifier bridge circuit according to claim 2, characterized in that: The auxiliary circuit is a PNP pair of transistors connected to the source and drain ends of the PMOS main tube; The emitters of the PNP pair are connected to the drain and source of the PMOS main tube respectively, the collectors of the PNP pair are connected to the collector resistors R1A and R1B respectively, the base of the front-end PNP tube is connected to the collector resistor R1A, and the gate of the PMOS main tube is connected to the collector resistor R1B.

5. A low-loss three-phase rectifier bridge circuit according to claim 2, characterized in that: The auxiliary circuit is a voltage comparator connected to the source and drain terminals of the PMOS tube; The in-phase terminal and the inverting terminal of the voltage comparator are respectively connected to the drain and source of the PMOS tube, and the gate of the PMOS tube is connected to the output terminal of the voltage comparator and connected to the rectifier power supply output terminal Vout through a pull-up resistor.

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