CN218940745U

CN218940745U - Electric automobile charger and AC-DC circuit thereof

Info

Publication number: CN218940745U
Application number: CN202222459588.XU
Authority: CN
Inventors: 吴军伟; 齐红柱; 陈斌; 孙艳芳; 张紫阳; 陈洪闯
Original assignee: Zhengzhou Senyuan New Energy Technology Co ltd; Henan Senyuan Electric Co Ltd
Current assignee: Zhengzhou Senyuan New Energy Technology Co ltd; Henan Senyuan Electric Co Ltd
Priority date: 2022-09-16
Filing date: 2022-09-16
Publication date: 2023-04-28
Anticipated expiration: 2032-09-16

Abstract

The utility model belongs to the technical field of power electronics, and particularly relates to an electric vehicle charger and an AC-DC circuit thereof, wherein the AC-DC circuit comprises three groups of rectifying circuits and a direct current booster circuit, and the input end of each group of rectifying circuits is respectively used for being connected with one phase of a three-phase power supply; the output ends of the three groups of rectifying circuits are respectively connected with the corresponding direct current booster circuits and then connected together to form a total output end, and the total output end is used for being connected with the input end of the DC-DC circuit corresponding to the charger so as to provide direct current power for the DC-DC circuit. The DC power supply which is output after each phase of the three-phase power supply is modulated by the rectifying circuit and the boosting circuit is connected together to form a total output end for the subsequent stage DC-DC circuit, and the AC-DC circuit based on the utility model does not need programming, thereby simplifying the design of the circuit and reducing the hardware cost of using a digital control mode.

Description

Electric automobile charger and AC-DC circuit thereof

Technical Field

The utility model belongs to the technical field of power electronics, and particularly relates to an electric vehicle charger and an AC-DC circuit thereof.

Background

The electric energy is frequently used in daily life, and along with the development of electric appliances, high-power electric equipment is increased at present, and the requirement of the high-power electric equipment on the power factor is higher, and the direct input of the commercial power cannot meet the requirement of the high-power equipment on the power factor, so that in order to improve the power factor, a power factor correction circuit is additionally arranged at the input end of a power supply in the prior art.

In the prior art, a 6.6KW-10KW high-power device (such as an electric automobile charger) needs to use a three-phase power supply to supply power to the high-power device, and based on the development of digital technology, a Digital Signal Processor (DSP) can realize more control strategies, so that the research of active power factor correction is concentrated on the aspect of digital control technology, therefore, the power factor correction circuit of the 6.6KW-10KW high-power device adopts a digital control mode, but the digital control mode needs a large amount of algorithm programming, so that the design complexity of the power factor correction circuit is high, namely, the design complexity of an AC-DC circuit for providing a DC power supply for the DC-DC circuit is high by adopting the digital control mode, and the cost of the AC-DC circuit using the digital signal processor is higher.

Disclosure of Invention

The utility model aims to provide an electric vehicle charger and an AC-DC circuit thereof, which are used for solving the problems of high circuit design complexity and high cost of an AC-DC circuit which adopts a digital control mode to provide a DC-DC circuit with a direct current power supply in the prior art.

In order to solve the technical problems, the utility model provides an AC-DC circuit of an electric vehicle charger, which comprises three groups of rectifying circuits and three groups of direct current booster circuits, wherein the input ends of the three groups of rectifying circuits are respectively used for being connected with one phase of a three-phase power supply; the output ends of the three groups of rectifying circuits are respectively connected with the corresponding direct current booster circuits and then connected together to form a total output end, and the total output end is used for being connected with the input end of the DC-DC circuit corresponding to the charger so as to provide a direct current power supply for the DC-DC circuit.

The beneficial effects are as follows: the DC power supply which is output after each phase of the three-phase power supply is modulated by the rectifying circuit and the boosting circuit is connected together to form a total output end for the subsequent stage DC-DC circuit, and the AC-DC circuit based on the utility model does not need programming, thereby simplifying the design of the circuit and reducing the hardware cost of using a digital control mode.

Further, the device also comprises an analog control chip; the direct-current booster circuit is a Boost booster circuit, and the analog control chip is connected with the control end of the Boost booster circuit and used for providing PWM waves for the Boost booster circuit.

The boosting process is an energy transfer process of an inductor, and the inductor absorbs energy during charging and discharges energy during discharging. The Boost circuit is a switching direct current Boost circuit that can change direct current into direct current of another fixed voltage or adjustable voltage, and the Boost circuit can make the output voltage higher than the input voltage.

Further, the diode in the Boost circuit is a silicon carbide schottky diode.

The silicon carbide Schottky diode is a unipolar device and adopts a junction barrier Schottky diode structure, so that compared with a traditional silicon fast recovery diode, the silicon carbide Schottky diode has ideal reverse recovery characteristics, almost no reverse recovery current exists when the device is switched from forward conduction to reverse blocking, the reverse recovery time is less than 20ns, and the reverse recovery time of the silicon carbide Schottky diode of 600V10A is within 10 ns. The silicon carbide schottky diode can therefore operate at a higher frequency with higher efficiency at the same frequency.

Further, the protection diode is connected in parallel with the inductor and the two ends of the diode of the Boost circuit.

The protection principle of the protection diode is as follows: the diode, especially the switch tube in the circuit, can be protected, because the diode is the fast recovery diode (because the switch tube is turned off when the inductance current is not zero, need bear bigger stress, require the diode to have extremely low or even zero reverse recovery current), bear surge current's ability weak, reduce reverse recovery current and improve surge voltage bearing capacity and be the mutual restriction, and the protection diode adopts ordinary rectifier diode, bears surge current's ability very strong, namely this protection diode has reduced the surge impact to inductance and diode.

Further, a filter circuit is further arranged between the output end of the rectifying circuit and the direct-current boost circuit.

A filter circuit is arranged between the rectifying circuit and the direct-current boost circuit so as to filter power supply interference under the high-voltage condition.

Further, an anti-reflection diode is further arranged between the direct current booster circuit and the connecting node.

By arranging the anti-reflection diode, current can only flow along the forward direction (the diode conducting direction) of the diode, and the phenomenon of current backflow is avoided.

Further, the direct current booster circuit is two Boost booster circuits which are arranged in parallel.

Each circuit structure is internally provided with two Boost circuits which are arranged in parallel, so that when one Boost circuit fails, the other Boost circuit is used for boosting, and the normal operation of the AC-DC circuit is ensured.

In order to solve the technical problems, the utility model also provides an electric vehicle charger which comprises a three-phase input end of a three-phase power supply, a DC-DC circuit and the AC-DC circuit of the electric vehicle charger, and achieves the same beneficial effects as the circuit.

Drawings

FIG. 1 is a schematic block diagram of a charger AC-DC circuit of the present utility model

FIG. 2 is a phase A schematic of the charger AC-DC circuit of the present utility model;

FIG. 3 is a B-phase schematic of the charger AC-DC circuit of the present utility model;

fig. 4 is a C-phase schematic of the charger AC-DC circuit of the present utility model.

Detailed Description

The present utility model will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present utility model more apparent.

An embodiment of an AC-DC circuit of an electric vehicle charger:

as shown in fig. 1, the AC-DC circuit of the charger in this embodiment is composed of three groups of rectifying circuits and three groups of DC boost circuits, and the input end of each group of rectifying circuits is used for connecting one phase of a three-phase power supply; the output ends of the three groups of rectifying circuits are respectively connected together through corresponding direct current booster circuits to form a total output end, and the total output end is used for being connected with the input end of the DC-DC circuit corresponding to the charger so as to provide direct current power for the DC-DC circuit.

The DC power supply which is output after each phase of the three-phase power supply is modulated by the rectifying circuit and the boosting circuit is connected together to form a total output end for the subsequent stage DC-DC circuit, and the AC-DC circuit based on the utility model does not need programming, thereby simplifying the design of the circuit and reducing the hardware cost of using a digital control mode. The power factor correction device can be directly applied to a power factor correction circuit without programming, and can be controlled correspondingly according to a feedback signal of the boost circuit.

As shown in fig. 2, 3 and 4, three live wires of the three-phase power supply are respectively connected with one end of the input end of each rectifying circuit, and the other end of each input end is used for being connected with a zero line; the output end of each boost circuit (namely, the direct current boost circuit) is collected and then used as the total output end of the whole AC-DC circuit (the (1) end in the figure 2 is connected with the (1) end in the figure 3, the (2) end in the figure 2 is connected with the (2) end in the figure 4), and the total output end is connected with the input end of the post-stage DC-DC circuit of the AC-DC of the charger to provide a direct current power supply after power factor correction for the DC-DC converter; the rectifying circuit is used for converting input alternating current into direct current and is used by the Boost circuit (the Boost circuit in the embodiment is a Boost circuit); the boosting process is an energy transfer process of an inductor, the inductor absorbs energy when charging and discharges energy when discharging, the Boost boosting circuit is a switch direct current boosting circuit, the switch direct current boosting circuit can convert direct current into direct current with another fixed voltage or adjustable voltage, the Boost boosting circuit can make output voltage higher than input voltage, in the embodiment, the diode in the Boost boosting circuit is a silicon carbide schottky diode (such as D3 and D7 in fig. 2 are both silicon carbide schottky diodes), the silicon carbide schottky diode is a unipolar device, and a junction barrier schottky diode structure is adopted, so compared with a traditional silicon fast recovery diode, the silicon carbide schottky diode has ideal reverse recovery characteristic, when the device is switched from forward conduction to reverse blocking, the reverse recovery time is less than 20ns, and the reverse recovery time of the silicon carbide schottky diode of even 600V10A is within 10 ns. The silicon carbide schottky diode can therefore operate at a higher frequency with higher efficiency at the same frequency.

In the embodiment, each circuit structure is provided with two Boost circuits which are arranged in parallel, so that when one Boost circuit fails, the other Boost circuit is used for boosting, and the normal operation of the AC-DC circuit is ensured; for example, the Boost circuits with input ends being a-N ends (as shown in fig. 2), one Boost circuit is formed by an inductor L1, a diode D3, a switching tube Q1 and a switching tube Q4, another Boost circuit is formed by the inductor L3, the diode D7, the switching tube Q7 and the switching tube Q8, on-off of each Boost circuit (i.e. on-off of two switching tubes in each Boost circuit) in this embodiment is controlled by an analog chip UCC28070 (UCC 28070 is a power factor correction device, the dc Boost circuit can be directly applied without programming, and corresponding control can be given according to feedback signals of the dc Boost circuit), for example, the gate of the switching tube Q1 (i.e. the 1 end of Q1) is used for being connected with the GDA pin of UCC28070, the gate of the switching tube Q4 (i.e. the 1 end of Q4) is used for being connected with the GDB of UCC28070, the CSA pin of UCC28070 is connected with the CSB pin Q1 and the inverting pin of the switching tube Q4, and the current of the switching tube Q1 is connected with the inverting end of the switching tube Q4 is the inverting end of the switching tube Q2, and the current of the switching tube Q2 is controlled by the feedback signal of the switching tube Q2 is further controlled by the feedback signal of the switching tube Q2.

The power factor correction of the three-phase power supply is realized by setting the rectifying circuit and the Boost circuit and controlling the analog chip UCC28070 to realize the Boost process of each phase of the three-phase power supply and further taking the input ends of the three circuit structures in parallel as the total output. Compared with the method of realizing power factor correction by digital chip control in the prior art, the circuit designed by the embodiment does not need a large amount of programming, simplifies the design of the circuit, and reduces the hardware cost of using a digital control mode based on the mode of analog chip control in the embodiment. Each circuit structure in the embodiment is composed of two Boost circuits, so that the normal operation of the AC-DC circuit is further ensured.

In this embodiment, a high-frequency bypass filter capacitor is further disposed between the rectifying circuit and the Boost circuit to filter out power supply interference under a high-voltage condition, and an anti-reverse diode is also disposed behind the Boost circuit to avoid a current reverse flow phenomenon, and a protection diode is further connected in parallel to the Boost circuit (D1 in fig. 2, D2 in fig. 3, and D9 in fig. 4 are all protection diodes). The protection principle of the protection diode is as follows: the shunt diode D1 is protected in parallel, so that the diode D3, especially a switching tube in a circuit, can be protected, because D3 is a fast recovery diode (because the switching tube is turned off when the inductance current is not zero, and needs to bear larger stress, the diode is required to have extremely low or even zero reverse recovery current), the capability of bearing surge current is weak, the capability of reducing reverse recovery current and improving surge voltage bearing capacity is mutually limited, and D1 adopts a common rectifier diode, and the capability of bearing surge current is strong. The protection diode D1 reduces surging impact on the inductor L1 and the diode D3, but actually has an important function of protecting the switching tube: at the moment of starting up, the voltage of the filter capacitor is not established, because the large capacitor is charged, the current passing through the inductor L1 is relatively large, if the moment when the power switch is turned on is the maximum value of the sine wave, the inductor L1 is likely to be subjected to magnetic saturation in the process of charging the capacitor, and at the moment, under the condition of magnetic saturation, the current flowing through the switching tube loses limitation, and the switching tube is burnt out. In order to prevent the switch tube from being burnt out under the condition, the protection diode D1 is added (the D1 can select a rectifier diode which can bear a common high current with a large surge current), another branch is provided for charging the high capacitor at the moment of starting, the switch tube is prevented from being damaged by overcurrent, the function of protecting the switch tube is further achieved, and meanwhile, the protection diode D1 also shunts the current on the diode D3, and the diode is protected. In addition, the addition of D1 accelerates the charging process of the large capacitor, the voltage on the large capacitor is built in time, the voltage feedback loop of the Boost circuit can work in time, the conduction time of the switching tube during starting is reduced, the Boost circuit is further enabled to realize the boosting process as soon as possible, and the power factor correction efficiency is improved. In some power supplies, the capacitance capacity behind the Boost circuit is not large, and a protection diode is not connected, but if a filter capacitor with large capacity is used behind the Boost circuit, the diode cannot be reduced, which has important significance for the safety of the circuit, namely, the surge current of the large filter capacitor is limited because the inductor L1 is connected in series with the filter capacitor with large capacity behind the Boost circuit, and the current on the inductor L cannot be suddenly changed.

Electric automobile charger embodiment:

the charger in the embodiment comprises a three-phase input end of a three-phase power supply, an AC-DC circuit and a DC-DC circuit, wherein the AC-DC circuit comprises three groups of rectifying circuits and three groups of boosting circuits, and the input end of each group of rectifying circuits is used for being connected with one phase of the three-phase power supply; the output ends of the three groups of rectifying circuits are respectively boosted by the corresponding boosting circuits and then are collected into a total output end, and the total output end is connected with the input end of the corresponding DC-DC circuit so as to provide a direct current power supply after power factor correction for the DC-DC circuit; the control end of the boost circuit is connected with the analog control chip in a control mode, and the boost circuit is connected with the control end of the boost circuit in a control mode. The analog control chip adopts the UCC28070, and the AC-DC circuit of the electric vehicle charger is controlled by the UCC28070 to realize three-phase power factor correction, and the specific AC-DC circuit of the electric vehicle charger is sufficiently clear as described in the embodiment of the AC-DC circuit of the electric vehicle charger, and is not repeated here.

The above description is only a preferred embodiment of the present utility model, and the patent protection scope of the present utility model is defined by the claims, and all equivalent structural changes made by the specification and the drawings of the present utility model should be included in the protection scope of the present utility model.

Claims

1. The AC-DC circuit of the electric vehicle charger is characterized by comprising three groups of rectifying circuits and three groups of direct current booster circuits, wherein the input ends of the three groups of rectifying circuits are respectively used for being connected with one phase of a three-phase power supply; the output ends of the three groups of rectifying circuits are respectively connected with corresponding direct current booster circuits and then connected together to form a total output end; the total output end is used for being connected with the input end of the DC-DC circuit corresponding to the charger so as to provide direct current power supply for the DC-DC circuit.

2. The electric vehicle charger AC-DC circuit of claim 1, further comprising an analog control chip; the direct-current booster circuit is a Boost booster circuit, and the analog control chip is connected with the control end of the Boost booster circuit and used for providing PWM waves for the Boost booster circuit.

3. The electric vehicle charger AC-DC circuit of claim 2, wherein the diode in the Boost circuit is a silicon carbide schottky diode.

4. The electric vehicle charger AC-DC circuit of claim 2, further comprising a protection diode connected in parallel across the inductor and the diode of the Boost circuit.

5. The electric vehicle charger AC-DC circuit of claim 1, wherein a filter circuit is further provided between the output of the rectifying circuit and the DC boost circuit.

6. The electric vehicle charger AC-DC circuit of claim 1, wherein an anti-reflection diode is further provided between the direct current boost circuit and the connection node.

7. The electric vehicle charger AC-DC circuit of claim 1, wherein the direct current Boost circuit is two Boost circuits arranged in parallel.

8. An electric vehicle charger, characterized by comprising a three-phase input of a three-phase power supply, a DC-DC circuit and an electric vehicle charger AC-DC circuit according to any one of claims 1 to 7.