CN115549475A - Electric automobile and charging device and charging control method thereof - Google Patents

Abstract

The charging control method of the electric automobile is realized by means of a pre-charging sub-circuit which is connected with a high-voltage capacitor in series between a positive electrode and a negative electrode on the high-voltage side of a bidirectional DC/DC conversion circuit in the pre-charging process of the high-voltage capacitor, and the pre-charging sub-circuit is not positioned in a main loop of the charging device, so that the required rated current is small, the size is small, and the reduction of the whole size is facilitated; and the system does not need to perform additional communication interaction with an external control unit, and the control complexity is low. In addition, the pre-charging of the PFC bus capacitor is realized by the electric energy of the power battery by means of the reverse work of the bidirectional DC/DC conversion circuit, so that a buffer resistor and a relay thereof for limiting current charging current in the prior art can be omitted, the number of devices is reduced, the whole volume is reduced, and the power density is improved.

Description

Electric automobile and charging device and charging control method thereof

Technical Field

The application relates to the technical field of power electronics, in particular to an electric automobile, a charging device of the electric automobile and a charging control method of the electric automobile.

Background

An OBC (On-Board Charger) and an OBC & DC/DC (power conversion circuit from a high-voltage power battery to a low-voltage storage battery) two-in-one vehicle-mounted power supply are mainstream devices in the current market of vehicle-mounted charging devices, wherein a bidirectional power transmission function of the OBC gradually becomes a passenger vehicle standard due to V2X (vehicle to electric) requirements.

Referring to fig. 1, a corresponding buffer circuit is generally required to be connected in series in an ac side access loop of an OBC, a buffer resistor Rac of the OBC is used to limit a current charged in a PFC bus capacitor Cbus inside the OBC from the ac side, and when a voltage on the PFC bus capacitor Cbus is charged to a predetermined voltage, a relay K3 in the buffer circuit is controlled to be closed to bypass the buffer resistor Rac, so as to enter a normal charging mode. However, the presence of the snubber resistor Rac and the relay K3 not only increases the circuit cost, but also decreases the reliability thereof, while being detrimental to the size reduction of the OBC.

Moreover, the high-voltage capacitor Chv on the OBC power battery side also needs to be equipped with a corresponding precharge circuit, which specifically includes: relays K4 and K5 and a buffer resistor Rhv; when the relay K4 is closed, the buffer resistor Rhv can be used for limiting the current charged into the high-voltage capacitor Chv by the power battery; when the relay K5 is closed, the snubber resistor Rhv can be bypassed. However, in practical applications, if the pre-charging circuit is disposed on the OBC, the OBC is not easy to be reduced in size; if the pre-charging circuit is placed on a power distribution module of an electric Vehicle, a Vehicle-mounted power supply control unit inside the OBC is difficult to directly control, extra communication interaction needs to be performed through a BMS (battery management System) or a VCU (Vehicle control unit), pre-charging control of the high-voltage capacitor Chv is performed through an OBC external control unit, and complexity is improved.

Therefore, how to reduce the number of devices of the OBC and reduce the control complexity, and increase the power density becomes very important.

Disclosure of Invention

In view of this, the present application provides an electric vehicle, a charging apparatus thereof and a charging control method thereof, so as to reduce the number of components of the OBC, reduce the control complexity, and improve the power density.

In order to achieve the above purpose, the present application provides the following technical solutions:

the application provides a charging control method of an electric vehicle, wherein a charging device of the electric vehicle comprises a bidirectional PFC circuit and a bidirectional DC/DC conversion circuit which are connected in a cascade manner, and a PFC bus capacitor is connected between the positive pole and the negative pole of the connection point of the bidirectional PFC circuit and the bidirectional DC/DC conversion circuit; the secondary side of the bidirectional DC/DC conversion circuit is used as a high-voltage side and is used for connecting a power battery in the electric automobile, and a high-voltage capacitor and a pre-charging sub-circuit are connected in series between the positive electrode and the negative electrode of the bidirectional DC/DC conversion circuit; the charging control method comprises the following steps:

collecting the high-voltage side output voltage of the bidirectional DC/DC conversion circuit;

when the difference between the output voltage of the high-voltage side and the voltage of the power battery is within a preset range, controlling the pre-charging sub-circuit to act to complete pre-charging of the high-voltage capacitor;

controlling the bidirectional DC/DC conversion circuit to work, and controlling the bidirectional DC/DC conversion circuit to stop working after the power of the power battery is used for realizing the pre-charging of the PFC bus capacitor;

and informing power supply equipment connected to the alternating current side of the bidirectional PFC circuit to realize the connection between an alternating current power supply and the charging device, and entering a normal charging mode of the power battery.

Optionally, the pre-charge sub-circuit includes a buffer resistor and a relay connected in parallel;

in the charging control method, controlling the pre-charge sub-circuit to operate includes: and controlling the relay to be closed.

Optionally, the high-voltage side of the bidirectional DC/DC conversion circuit is connected to the power battery through a main contactor;

before collecting the output voltage of the high-voltage side of the bidirectional DC/DC conversion circuit, the charging control method further comprises the following steps:

notifying an external controller of the charging device to close the main contactor.

Optionally, when the voltage on the PFC bus capacitor reaches a preset voltage, it is determined that the pre-charging of the PFC bus capacitor is completed.

Optionally, the preset voltage is greater than a voltage peak of the ac power supply.

Optionally, the ground terminal of the charging device is connected to the vehicle body ground and is connected to the charging control terminal of the power supply device through the controllable switch;

in the charging control method, notifying a power supply device connected to an ac side of the bidirectional PFC circuit to realize connection between an ac power supply and the charging device includes: controlling the controllable switch to close.

Optionally, before acquiring the high-voltage side output voltage of the bidirectional DC/DC conversion circuit, the method further includes:

and receiving a charging request instruction.

Optionally, the charging device further includes: the DC/DC circuit is connected between the high-voltage side of the bidirectional DC/DC conversion circuit and a low-voltage storage battery of the electric automobile;

after receiving the charging request command, the charging control method further includes:

judging whether the DC/DC circuit is in a working state;

and if the DC/DC circuit is in a working state, directly executing the step of controlling the bidirectional DC/DC conversion circuit to work.

Optionally, the charging apparatus further includes: the alternating current of the AC/DC circuit is connected with an auxiliary winding of a transformer in the bidirectional DC/DC conversion circuit, and the direct current side of the AC/DC circuit is connected with a low-voltage storage battery of the electric automobile;

after receiving the charging request command, the charging control method further includes:

judging whether the AC/DC circuit is in a working state;

if the AC/DC circuit is in a working state, judging whether the voltage on the PFC bus capacitor reaches a preset voltage or not;

if the voltage on the PFC bus capacitor reaches the preset voltage, directly informing power supply equipment connected to the AC side of the bidirectional PFC circuit to realize the connection between an AC power supply and the charging device;

and if the voltage on the PFC bus capacitor does not reach the preset voltage, controlling a primary side circuit in the bidirectional DC/DC conversion circuit to work, after the voltage on the PFC bus capacitor is charged to the preset voltage, controlling the bidirectional DC/DC conversion circuit to stop working, and then informing power supply equipment connected to the alternating current side of the bidirectional PFC circuit to realize the connection between the alternating current power supply and the charging device.

The second aspect of the present application provides a charging device for an electric vehicle, comprising: the control unit, the bidirectional PFC circuit, the PFC bus capacitor, the bidirectional DC/DC conversion circuit, the high-voltage capacitor and the pre-charging sub-circuit; wherein, the first and the second end of the pipe are connected with each other,

the alternating current side of the bidirectional PFC circuit is connected with the inner side of an alternating current side interface of the charging device;

the direct current side of the bidirectional PFC circuit is connected with the primary side of the bidirectional DC/DC conversion circuit; the PFC bus capacitor is connected between the positive electrode and the negative electrode of the direct current side of the bidirectional PFC circuit;

the secondary side of the bidirectional DC/DC conversion circuit is used as a high-voltage side and is connected with the inner side of a power battery side interface of the charging device; the high-voltage capacitor and the pre-charging sub-circuit are connected in series between the positive electrode and the negative electrode of the high-voltage side of the bidirectional DC/DC conversion circuit;

the outer side of a power battery side interface of the charging device is connected with a power battery of the electric automobile through a main contactor;

the bidirectional PFC circuit, the bidirectional DC/DC conversion circuit, and the pre-charge sub-circuit are all controlled by the control unit, and the control unit is configured to execute the method for controlling charging of an electric vehicle according to any one of the first aspect.

Optionally, the pre-charge sub-circuit includes: a buffer resistor and a relay;

the buffer resistor is connected with the relay in parallel, and two ends of the buffer resistor after being connected in parallel are respectively used as two ends of the pre-charging sub-circuit;

the relay is controlled by the control unit.

Optionally, the rated current of the relay is smaller than a preset current value.

Optionally, the main contactor is controlled by an external controller of the charging device;

the control unit is in communication connection with the external controller.

Optionally, the bidirectional DC/DC conversion circuit includes: the transformer, the primary circuit and the secondary circuit;

the direct current side of the primary side circuit is used as the primary side of the bidirectional DC/DC conversion circuit;

the alternating current side of the primary side circuit is connected with the primary side winding of the transformer;

a secondary winding of the transformer is connected with the alternating current side of the secondary circuit;

the direct current side of the secondary side circuit is used as the secondary side of the bidirectional DC/DC conversion circuit.

Optionally, the method further includes: a DC/DC circuit for realizing high-voltage to low-voltage conversion;

the first side of the DC/DC circuit is connected with the high-voltage side of the bidirectional DC/DC conversion circuit;

and the second side of the DC/DC circuit is used for connecting a low-voltage storage battery of the electric automobile.

Optionally, the method further includes: an AC/DC circuit;

the first side of the AC/DC circuit is connected with an auxiliary winding of a transformer in the bidirectional DC/DC conversion circuit;

and the second side of the AC/DC circuit is used for connecting a low-voltage storage battery of the electric automobile.

A third aspect of the present application provides an electric vehicle, wherein an onboard power supply of the electric vehicle is a charging device of the electric vehicle according to any one of the second aspects;

and the grounding end of the charging device is connected with the vehicle body ground and is connected with the charging control end of the vehicle control device in the electric vehicle and the charging control end of the external power supply equipment through the controllable switch.

The charging control method of the electric automobile comprises the steps of firstly collecting the high-voltage side output voltage of a bidirectional DC/DC conversion circuit, and controlling a pre-charging sub-circuit to act when the difference between the high-voltage side output voltage and the voltage of a power battery is within a preset range to complete pre-charging of a high-voltage capacitor; that is, the pre-charging process of the high-voltage capacitor is realized by means of the pre-charging sub-circuit which is connected with the high-voltage capacitor in series between the positive electrode and the negative electrode at the high-voltage side of the bidirectional DC/DC conversion circuit, and the pre-charging sub-circuit is not positioned in the main loop of the charging device, so that the required rated current is small, the volume is small, and the reduction of the whole size is facilitated; moreover, whether the pre-charging sub-circuit acts can be determined only by collecting the output voltage of the high-voltage side, additional communication interaction with an external control unit is not needed, and the control complexity is low. In addition, after the high-voltage capacitor is precharged, the bidirectional DC/DC conversion circuit is controlled to work, the precharging of the PFC bus capacitor is realized by the electric energy of the power battery, then the bidirectional DC/DC conversion circuit is controlled to stop working, power supply equipment connected to the alternating current side of the bidirectional PFC circuit is informed to realize the connection between the alternating current power supply and the charging device, and the normal charging mode of the power battery is entered; that is, the pre-charging of the PFC bus capacitor is realized by the electric energy of the power battery by means of the reverse operation of the bidirectional DC/DC conversion circuit, so that a buffer resistor and a relay thereof for limiting the current charging current in the prior art can be omitted, the number of devices is reduced, the whole volume is reduced, and the power density is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the embodiments or the description of the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a vehicle-mounted charger provided in the prior art;

fig. 2 is a schematic structural diagram of a charging device for an electric vehicle according to an embodiment of the present disclosure;

fig. 3 is a flowchart of a charging control method for an electric vehicle according to an embodiment of the present application;

fig. 4 is a schematic diagram illustrating a connection relationship between a charging device and a power supply device of an electric vehicle according to an embodiment of the present application;

fig. 5 is another flowchart of a charging control method for an electric vehicle according to an embodiment of the present application;

fig. 6 is another flowchart of a charging control method for an electric vehicle according to an embodiment of the present application;

fig. 7 is another schematic structural diagram of a charging device for an electric vehicle according to an embodiment of the present application;

fig. 8 is another flowchart of a charging control method for an electric vehicle according to an embodiment of the present application;

fig. 9 is another schematic structural diagram of a charging device for an electric vehicle according to an embodiment of the present application;

fig. 10 is another flowchart of a charging control method for an electric vehicle according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

The application provides a charging control method of an electric automobile, which aims to reduce the number of OBC devices, reduce the control complexity and improve the power density.

The electric vehicle charges the power battery through the charging device, referring to fig. 2, the charging device adopts a two-stage topology composed of PFC + DC/DC, and specifically includes: the control circuit comprises a control unit 100, a bidirectional PFC circuit 101, a PFC bus capacitor Cbus, a bidirectional DC/DC conversion circuit 102, a high-voltage capacitor Chv and a pre-charging sub-circuit 103; wherein:

the bidirectional PFC circuit 101 and the bidirectional DC/DC conversion circuit 102 are connected in cascade, and a PFC bus capacitor Cbus is connected between the positive pole and the negative pole of the connection point of the bidirectional PFC circuit 101 and the bidirectional DC/DC conversion circuit 102.

The ac side of the bidirectional PFC circuit 101 is connected to the inside of the ac side interface of the charging device; the outside of the AC side interface of the charging device is used for connecting power supply equipment, such as an AC charging pile.

The secondary side of the bidirectional DC/DC conversion circuit 102 is used as a high voltage side for connecting a power battery in an electric vehicle, and the power battery can be connected through a main contactor K5. And the high-voltage capacitor Chv and the pre-charge sub-circuit 103 are connected in series between the positive and negative electrodes of the high-voltage side of the bidirectional DC/DC conversion circuit 102.

Moreover, the pre-charge sub-circuit 103 is controlled by the control unit 100 to pre-charge the high-voltage capacitor Chv; the bidirectional PFC circuit 101 and the bidirectional DC/DC conversion circuit 102 are also controlled by the control unit 100, and further, the power battery may be charged with the electric energy of the ac side interface in a state where the main contactor K5 is closed, or the pre-charging of the PFC bus capacitor Cbus may be realized with the electric energy of the power battery.

As shown in fig. 2, the pre-charge sub-circuit 103 may specifically include: the buffer resistor Rhv and the relay K4 are connected in parallel; the relay K4 and the main contactor K5 are both controlled by the control unit 100, when the main contactor K5 is closed, the electric energy of the power battery can charge the high-voltage capacitor Chv through the buffer resistor Rhv, and when the voltage of the power battery is charged to be close to the voltage of the power battery, the relay K4 can be controlled to be closed, and the buffer resistor Rhv is bypassed.

Referring to fig. 3, the charging control method of the electric vehicle specifically includes:

s101, collecting the high-voltage side output voltage of the bidirectional DC/DC conversion circuit.

When the ac-side interface of the charging device is connected to a power supply device, for example, the charging device is used as a vehicle-mounted power supply of an electric vehicle, and specifically, a charging gun of an ac charging pile is inserted into an ac port of the electric vehicle, at this time, the control unit 100 in fig. 2 detects a high-voltage-side output voltage of the bidirectional DC/DC conversion circuit 102, that is, a total voltage of a high-voltage capacitor Chv and a pre-charging sub-circuit 103 connected in series.

Before the main contactor K5 is closed, the output voltage of the high-voltage side is 0; after the main contactor K5 is closed, the power battery charges the high-voltage capacitor Chv through the main relay K5 and the pre-charging resistor Rhv, when the voltage on the high-voltage capacitor Chv is charged to be stable, the voltage on the high-voltage capacitor Chv is the same as that of the power battery, the voltage on the buffer resistor Rhv is zero, and the output voltage of the high-voltage side is the voltage on the high-voltage capacitor Chv.

And S102, when the difference between the output voltage of the high-voltage side and the voltage of the power battery is in a preset range, controlling the pre-charging sub-circuit to act, and completing the pre-charging of the high-voltage capacitor.

The preset range may be a value range centered at 0, and is not specifically limited herein, and may be determined according to an application environment, and all of the preset ranges are within the scope of the present application.

The control unit 100 can judge whether the main relay K5 is closed only by sampling the output voltage at the high-voltage side, and can control the pre-charge sub-circuit to operate by waiting for a period of time after sampling to ensure that the charging of the high-voltage capacitor Chv is completed. Controlling the pre-charging sub-circuit to act in the step specifically means controlling a relay K4 shown in FIG. 2 to be closed, so that the buffer resistor Rhv is bypassed; through the pre-charging process, no current impact on the high-voltage capacitor Chv can be ensured.

In practical applications, the control unit 100 may detect the output voltage of the high-voltage side in real time, and when the output voltage of the high-voltage side is within a certain range of the voltage of the power battery and the voltage does not change substantially, it is determined that the output voltage of the high-voltage side matches the voltage of the power battery, and the high-voltage capacitor Chv is charged completely, so as to control the relay K4 to be turned on.

S103, controlling the bidirectional DC/DC conversion circuit to work, and controlling the bidirectional DC/DC conversion circuit to stop working after the pre-charging of the PFC bus capacitor is realized by the electric energy of the power battery.

In fig. 2, the control unit 100 controls the bidirectional DC/DC conversion circuit 102 to operate in reverse, and charges the PFC bus capacitor Cbus with the power of the power battery; when the voltage of the PFC bus capacitor Cbus reaches the preset voltage, it may be determined that the pre-charging of the PFC bus capacitor Cbus is completed, and the bidirectional DC/DC conversion circuit 102 is stopped.

In practical application, the preset voltage is greater than the voltage peak value of the alternating current power supply, and specific values of the preset voltage are not limited and are determined according to application environments of the alternating current power supply.

And S104, informing power supply equipment connected to the alternating current side of the bidirectional PFC circuit to realize the connection between the alternating current power supply and the charging device, and entering a normal charging mode of the power battery.

After the pre-charging of both capacitors is completed, the control unit 100 shown in fig. 2 may request the internal relay of the power supply device, such as the ac charging post, to be turned on, so as to connect the ac power source of the ac charging post and the charging device.

In practical application, referring to fig. 4, the ground terminal of the charging device is connected to the vehicle body ground, and may be connected to the charging control terminal of the power supply device through the controllable switch S2; at this time, in step S104, the power supply device connected to the ac side of the bidirectional PFC circuit is notified to implement connection between the ac power supply and the charging apparatus, which may specifically be: controlling the controllable switch S2 to be closed, that is, the control unit 100 in fig. 2 is further configured to output a control signal for the controllable switch S2; at this time, after the power supply control device in the power supply equipment confirms the readiness of the charging device by measuring the voltage of the detection point 1, the relays K1 and K2 in the alternating current transmission branch can be controlled to be switched on, and the connection between the alternating current power supply and the charging device is completed.

It is worth to be noted that, when the charging device is in normal operation, that is, in a normal charging mode, the current of the high-voltage capacitor Chv is smaller than the current transmitted to the power battery, so the relay K4 can select a low-current relay, and the occupied volume of the relay K on the vehicle-mounted power supply is smaller.

The charging control method for the electric vehicle provided by the embodiment is realized by the pre-charging sub-circuit which is connected with the high-voltage capacitor in series between the positive electrode and the negative electrode at the high-voltage side of the bidirectional DC/DC conversion circuit in the pre-charging process of the high-voltage capacitor, and the pre-charging sub-circuit is not positioned in the main loop of the charging device, so that the required rated current is small, the volume is small, and the reduction of the whole size is facilitated; moreover, whether the pre-charging sub-circuit acts or not can be determined only by collecting the output voltage of the high-voltage side, additional communication interaction with an external control unit is not needed, and the control complexity is low. In addition, the pre-charging of the PFC bus capacitor is realized by the electric energy of the power battery by utilizing the power bidirectional transmission characteristic of the charging device and by means of the reverse work of the bidirectional DC/DC conversion circuit, so that the overcurrent damage of a semiconductor device caused by the fact that a power grid transmits larger current to the PFC bus capacitor when an internal relay of the alternating-current charging pile is closed is avoided, the buffer resistor and the relay which limit the current charging current in the prior art can be omitted, the number of devices is reduced, the whole volume is reduced, and the power density is improved.

In addition to the above embodiment, in practical applications, the main contactor K5 shown in fig. 2 connected between the high-voltage side of the bidirectional DC/DC conversion circuit 102 and the power battery may be disposed outside the charging device and controlled by an external controller, such as other control units like BMS/VCU of the electric vehicle.

At this time, before collecting the high-voltage side output voltage of the bidirectional DC/DC conversion circuit in step S101, the charging control method further includes the steps shown in fig. 5:

and S100, informing an external controller of the charging device to close the main contactor.

After the charging gun of the ac charging pile is inserted into the ac port of the electric vehicle, the control unit 100 notifies other control units such as the BMS/VCU through communication after detecting that the charging gun is inserted and completely connected, and the other control units such as the BMS/VCU control the closing of the main relay K5, so that the control unit 100 detects the output voltage at the high voltage side.

When the control unit 100 determines that the difference between the high-voltage side output voltage and the voltage of the power battery is within the preset range, the relay K4 in the pre-charge sub-circuit 103 may be closed, and the pre-charge of the high-voltage capacitor Chv may be implemented without interacting the state information of the main relay K5 and the voltage of the high-voltage side output voltage and the voltage of the power battery with other control units such as BMS/VCU.

Meanwhile, the main contactor K5 is placed outside the charging device, the number of devices inside the charging device can be reduced, and extra communication interaction is not needed.

In addition to the above embodiments, preferably, referring to fig. 6 (which is shown as an example on the basis of fig. 5), before the step S101 of collecting the high-voltage side output voltage of the bidirectional DC/DC conversion circuit, the charging control method further includes:

and S200, receiving a charging request instruction.

Referring to fig. 2, in practical application, after the charging device is connected to the power supply device, specifically, after a charging request instruction of the power supply device is received, a relay K4 on the charging device is controlled by collecting a high-voltage side output voltage of the charging device, so that a high-voltage capacitor Chv is connected to a power battery; then, the bidirectional DC/DC conversion circuit 102 is controlled to run reversely, so that the power battery is stopped after charging the PFC bus capacitor Cbus to a specified threshold value; and sending a ready instruction to the alternating-current charging pile to inform the alternating-current charging pile to control a relay in an alternating-current transmission branch to be closed, so that connection between an alternating-current power supply of the alternating-current charging pile and the charging device is completed.

It is worth to be noted that there is a scheme in the prior art, on the basis of removing the buffer resistor and the relay on the ac side, the low-voltage storage battery of the electric vehicle is controlled to charge the high-voltage capacitor and the PFC bus capacitor, and then the ac power is switched in. Although the scheme can also omit an alternating current side buffer resistor and a relay thereof, the scheme is only suitable for a topological structure integrated with a low-voltage storage battery power conversion circuit, and all the power is taken from a low-voltage side storage battery, and in addition, the control mode can be used only when all circuits in the scheme are not in operation, so that the flexibility is poor.

The charging control method provided by the application does not need to take electricity from the low-voltage storage battery, and can be applied to a topology structure without the low-voltage storage battery power conversion circuit shown in fig. 2, more preferably, the charging control method can also be applied to a topology structure integrated with the low-voltage storage battery power conversion circuit, and can also be applied to a case that part of internal circuits are already working, specifically:

referring to fig. 7, the charging device is based on fig. 2, and further includes: and a DC/DC circuit 104 for converting high voltage into low voltage, wherein the DC/DC circuit 104 is connected between the high voltage side of the bidirectional DC/DC conversion circuit 102 and the low voltage battery of the electric vehicle.

At this time, as shown in fig. 8, the charging control method further includes, after receiving the charging request command in step S200:

s201, judging whether the DC/DC circuit is in a working state.

When an ac-side interface of the charging device is connected to a power supply device, for example, after a charging gun of an ac charging pile is inserted into an ac port of an electric vehicle, if the DC/DC circuit 104 in fig. 7 is in a working state, it indicates that the main relay K5 and the relay K4 are already closed, and the high-voltage capacitor Chv does not need to be precharged again, at this time, step S103 may be directly executed, that is, the bidirectional DC/DC conversion circuit 102 is directly controlled to work, and the PFC bus capacitor Cbus is charged; stopping the bidirectional DC/DC conversion circuit 102 when the voltage of the PFC bus capacitor Cbus reaches a preset voltage, executing a step S104, and requesting the conduction of relays (K1 and K2 shown in figure 4) inside the alternating-current charging pile to realize the connection between the alternating-current power supply of the alternating-current charging pile and the vehicle-mounted power supply; if the DC/DC circuit 104 in fig. 7 is not in an operating state, it needs to be executed from step S100.

In practical applications, another implementation manner of the low-voltage battery power conversion circuit can be seen in fig. 9, in this case, the charging apparatus is based on fig. 2, and further includes: and an AC/DC circuit 105 having an AC side connected to an auxiliary winding of the transformer in the bidirectional DC/DC conversion circuit 102 and a DC side connected to a low-voltage battery of the electric vehicle.

At this time, as shown in fig. 10, after receiving the charging request command at step S200, the charging control method further includes:

s202, judging whether the AC/DC circuit is in a working state.

Referring to fig. 9, since the AC/DC circuit 105 and the bidirectional DC/DC conversion circuit 102 share the secondary side circuit in the bidirectional DC/DC conversion circuit 102, if the AC/DC circuit 105 is in an operating state, it indicates that the secondary side circuit in the bidirectional DC/DC conversion circuit 102 is already in operation and is coupled to the primary side circuit through the transformer thereof, and there is a voltage on the PFC bus capacitor Cbus, and then step S203 needs to be further executed. If the AC/DC circuit 105 is not in operation, the operation is required from step S100.

S203, judging whether the voltage on the PFC bus capacitor reaches a preset voltage.

If the voltage on the PFC bus capacitor reaches the preset voltage, the PFC bus capacitor does not need to be precharged, the step S104 is directly executed, and power supply equipment connected to the AC side of the bidirectional PFC circuit is informed to realize the connection between the AC power supply and the charging device; however, if the voltage on the PFC bus capacitor does not reach the preset voltage, step S104 may be executed after step S204 is further executed.

And S204, controlling a primary side circuit in the bidirectional DC/DC conversion circuit to work, and controlling the bidirectional DC/DC conversion circuit to stop working after the voltage on the PFC bus capacitor is charged to a preset voltage.

The charging control method provided by the embodiment can be applied to various topological structures, can also be applied under the condition that part of circuits work, and is wide in application range.

Another embodiment of the present application further provides a charging device for an electric vehicle, which as shown in fig. 2, includes: the device comprises a control unit 100, a bidirectional PFC circuit 101, a PFC bus capacitor Cbus, a bidirectional DC/DC conversion circuit 102, a high-voltage capacitor Chv and a pre-charging sub-circuit 103; wherein:

the alternating current side of the bidirectional PFC circuit 101 is connected with the inner side of an alternating current side interface of the charging device; the outer side of the AC side interface of the charging device is used for connecting power supply equipment, such as an AC charging pile.

The direct current side of the bidirectional PFC circuit 101 is connected to the primary side of the bidirectional DC/DC conversion circuit 102; and a PFC bus capacitor Cbus is connected between the positive and negative poles on the dc side of the bidirectional PFC circuit 101.

The secondary side of the bidirectional DC/DC converter circuit 102 is connected to the inside of the power battery side interface of the charging device as a high-voltage side; the high-voltage capacitor Chv and the pre-charge sub-circuit 103 are connected in series between the positive electrode and the negative electrode on the high-voltage side of the bidirectional DC/DC conversion circuit 102; the outer side of a power battery side interface of the charging device is connected with a power battery of the electric automobile through a main contactor K5. The main contactor K5 is controlled by an external controller of the charging device, such as other control units in the BMS/VCU of the electric vehicle, and the control unit 100 is communicatively connected to the external controller.

Moreover, the pre-charge sub-circuit 103 is controlled by the control unit 100 to pre-charge the high-voltage capacitor Chv; the bidirectional PFC circuit 101 and the bidirectional DC/DC conversion circuit 102 are controlled by the control unit 100, and are configured to charge the power battery with the electric energy of the ac-side interface in a state where the main contactor K5 is closed, or to pre-charge the PFC bus capacitor Cbus with the electric energy of the power battery.

The control unit 100 is configured to execute the charging control method according to any of the embodiments, and the specific process and principle of the charging control method are described in the embodiments, which are not described in detail herein.

In practical applications, the pre-charge sub-circuit 103 may specifically include the following components shown in fig. 2: a buffer resistor Rhv and a relay K4; the buffer resistor Rhv is connected in parallel with the relay K4, and two ends of the parallel connection are respectively used as two ends of the pre-charge sub-circuit 103; the relay K4 is controlled by the control unit 100.

And the rated current of the relay K4 is smaller than the preset current value, so that the relay can be realized by selecting a low-current relay. The specific value of the preset current value depends on the application environment, and is not limited herein.

Referring to fig. 2, 7 or 9, the bidirectional DC/DC conversion circuit 102 includes: the transformer, the primary circuit and the secondary circuit; the DC side of the primary circuit is used as the primary side of the bidirectional DC/DC conversion circuit 102, the ac side of the primary circuit is connected to the primary winding of the transformer, the secondary winding of the transformer is connected to the ac side of the secondary circuit, and the DC side of the secondary circuit is used as the secondary side of the bidirectional DC/DC conversion circuit 102.

In practical applications, the charging device may further include: a DC/DC circuit 104 to effect high voltage to low voltage conversion; as shown in fig. 7, a first side of the DC/DC circuit 104 is connected to a high-voltage side of the bidirectional DC/DC conversion circuit 102, and a second side of the DC/DC circuit 104 is used for connecting a low-voltage battery of the electric vehicle; alternatively, as shown in fig. 9, the AC side of the AC/DC circuit 105 is connected to the auxiliary winding of the transformer in the bidirectional DC/DC conversion circuit 102, and the DC side of the AC/DC circuit 105 is used for connecting the low-voltage battery of the electric vehicle.

The charging device can be a vehicle-mounted power supply of an electric vehicle, in the embodiment, a high-voltage side partial pre-charging circuit (namely the pre-charging sub-circuit 103) is placed on the vehicle-mounted power supply in series, pre-charging of a high-voltage capacitor Chv is realized through self-sampling of the vehicle-mounted power supply, additional communication interaction is not needed, the volume of the vehicle-mounted power supply is reduced, then a bidirectional DC/DC conversion circuit 102 is used for charging a PFC bus capacitor Cbus to a preset voltage, a controllable switch S2 shown in a figure 4 is closed, alternating current access of an alternating current charging pile is controlled, a traditional vehicle-mounted power supply alternating current side pre-charging relay and a traditional pre-charging resistor are removed, instant current impact caused by alternating current access is avoided, the circuit structure is further simplified, the circuit cost is reduced, and meanwhile, the power density and the reliability of the circuit are improved; moreover, the present invention is applicable to a separate vehicle-mounted charger, or to a vehicle-mounted power supply in a different form, such as a vehicle-mounted charger integrated with a low-voltage battery power conversion circuit (e.g., the DC/DC circuit 104 shown in fig. 7 or the AC/DC circuit 105 shown in fig. 9). In addition, the charging device can also be a device independent of the electric automobile, and still has the advantages of small volume, few devices, low cost, low control complexity and the like.

Another embodiment of the present application further provides an electric vehicle, wherein a charging device of the electric vehicle according to any one of the above embodiments is provided in a vehicle-mounted power supply of the electric vehicle; the structure and principle of the charging device can be seen in the above embodiments, and are not described herein again.

As shown in fig. 4, the ground terminal of the charger mounted on the electric vehicle in the charging apparatus is connected to the vehicle body ground, and the charging control terminal of the vehicle control apparatus in the electric vehicle and the charging control terminal of the external power supply device are connected through the controllable switch S2.

In fig. 4, the power supply device may be an ac charging pile, a power supply control device and a leakage current protector are disposed inside the power supply device, a +12V voltage exists at a charging control end of the power supply control device, one end of a controllable switch S1 is connected to a charging control line CP, and the other end of the controllable switch S1 is connected to the charging control end or a PWM output pin of the power supply control device.

The power supply interface in fig. 4 may be a charging gun of the ac charging pile, and after the charging gun is inserted into the vehicle interface, corresponding connection between a charging wire (including L and N), a grounding wire PE, a charging connection wire CC and a charging control wire CP between the ac charging pile and the electric vehicle may be achieved. The mouth that charges of vehicle power supply is inserted, and vehicle power supply detects the rifle that charges and inserts and connect the back completely, can carry out the precharge to its inside high voltage capacitance and PFC bus capacitance, and when vehicle power supply confirmed the charged state ready, control wherein controllable switch S2 is closed, and when the voltage of alternating-current charging stake measurement check point 1 confirmed no problem, control relay K1 switched on with K2, accomplishes being connected between alternating-current charging stake alternating current and the vehicle power supply.

The same and similar parts among the various embodiments in the present specification are referred to each other, and each embodiment focuses on differences from other embodiments. In particular, the system or system embodiments, which are substantially similar to the method embodiments, are described in a relatively simple manner, and reference may be made to some descriptions of the method embodiments for relevant points. The above-described system and system embodiments are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (17)

1. The charging control method of the electric automobile is characterized in that a charging device of the electric automobile comprises a bidirectional PFC circuit and a bidirectional DC/DC conversion circuit which are connected in cascade, and a PFC bus capacitor is connected between the positive pole and the negative pole of the connection point of the two; the secondary side of the bidirectional DC/DC conversion circuit is used as a high-voltage side and is used for connecting a power battery in the electric automobile, and a high-voltage capacitor and a pre-charging sub-circuit are connected in series between the positive electrode and the negative electrode of the bidirectional DC/DC conversion circuit; the charging control method comprises the following steps:

collecting the high-voltage side output voltage of the bidirectional DC/DC conversion circuit;

when the difference between the output voltage of the high-voltage side and the voltage of the power battery is within a preset range, controlling the pre-charging sub-circuit to act to complete pre-charging of the high-voltage capacitor;

controlling the bidirectional DC/DC conversion circuit to work, and controlling the bidirectional DC/DC conversion circuit to stop working after the pre-charging of the PFC bus capacitor is realized by the electric energy of the power battery;

and informing power supply equipment connected to the alternating current side of the bidirectional PFC circuit to realize the connection between an alternating current power supply and the charging device, and entering a normal charging mode of the power battery.

2. The charge control method of an electric vehicle according to claim 1, wherein the pre-charge sub-circuit includes a snubber resistor and a relay connected in parallel;

in the charge control method, controlling the operation of the pre-charge sub-circuit includes: and controlling the relay to be closed.

3. The charging control method of an electric vehicle according to claim 1, wherein a high voltage side of the bidirectional DC/DC conversion circuit is connected to the power battery through a main contactor;

before the step of collecting the output voltage of the high-voltage side of the bidirectional DC/DC conversion circuit, the charging control method further comprises the following steps:

notifying an external controller of the charging device to close the main contactor.

4. The charging control method of an electric vehicle according to claim 1, wherein it is determined that the pre-charging of the PFC bus capacitor is completed when the voltage on the PFC bus capacitor reaches a preset voltage.

5. The charge control method of an electric vehicle according to claim 4, wherein the preset voltage is greater than a peak voltage value of the AC power source.

6. The method according to claim 1, wherein a ground terminal of the charging device is connected to a vehicle body ground and is connected to a charging control terminal of the power supply device through a controllable switch;

in the charging control method, notifying the power supply equipment connected to the alternating current side of the bidirectional PFC circuit to realize the connection between the alternating current power supply and the charging device includes: controlling the controllable switch to close.

7. The charging control method for the electric vehicle according to any one of claims 1 to 6, further comprising, before the step of collecting the high-side output voltage of the bidirectional DC/DC conversion circuit:

and receiving a charging request instruction.

8. The method of claim 7, wherein the charging device further comprises: the DC/DC circuit is used for realizing high-voltage to low-voltage conversion and is connected between the high-voltage side of the bidirectional DC/DC conversion circuit and a low-voltage storage battery of the electric automobile;

after receiving the charging request instruction, the charging control method further includes:

judging whether the DC/DC circuit is in a working state;

and if the DC/DC circuit is in a working state, directly executing the step of controlling the bidirectional DC/DC conversion circuit to work.

9. The method of claim 7, wherein the charging device further comprises: the alternating current side of the AC/DC circuit is connected with an auxiliary winding of a transformer in the bidirectional DC/DC conversion circuit, and the direct current side of the AC/DC circuit is connected with a low-voltage storage battery of the electric automobile;

after receiving the charging request instruction, the charging control method further includes:

judging whether the AC/DC circuit is in a working state;

if the AC/DC circuit is in a working state, judging whether the voltage on the PFC bus capacitor reaches a preset voltage or not;

if the voltage on the PFC bus capacitor reaches the preset voltage, directly informing power supply equipment connected to the AC side of the bidirectional PFC circuit to realize the connection between an AC power supply and the charging device;

and if the voltage on the PFC bus capacitor does not reach the preset voltage, controlling a primary side circuit in the bidirectional DC/DC conversion circuit to work, after the voltage on the PFC bus capacitor is charged to the preset voltage, controlling the bidirectional DC/DC conversion circuit to stop working, and then informing power supply equipment connected to the alternating current side of the bidirectional PFC circuit to realize the connection between the alternating current power supply and the charging device.

10. A charging device for an electric vehicle, comprising: the control unit, the bidirectional PFC circuit, the PFC bus capacitor, the bidirectional DC/DC conversion circuit, the high-voltage capacitor and the pre-charging sub-circuit; wherein the content of the first and second substances,

the alternating current side of the bidirectional PFC circuit is connected with the inner side of an alternating current side interface of the charging device;

the direct current side of the bidirectional PFC circuit is connected with the primary side of the bidirectional DC/DC conversion circuit; the PFC bus capacitor is connected between the positive electrode and the negative electrode of the direct current side of the bidirectional PFC circuit;

the secondary side of the bidirectional DC/DC conversion circuit is used as a high-voltage side and is connected with the inner side of a power battery side interface of the charging device; the high-voltage capacitor and the pre-charging sub-circuit are connected in series between the positive electrode and the negative electrode of the high-voltage side of the bidirectional DC/DC conversion circuit;

the outer side of a power battery side interface of the charging device is connected with a power battery of the electric automobile through a main contactor;

the bidirectional PFC circuit, the bidirectional DC/DC conversion circuit and the pre-charging sub-circuit are all controlled by the control unit, and the control unit is used for executing the charging control method of the electric automobile according to any one of claims 1 to 9.

11. The charging device of an electric vehicle according to claim 10, wherein the pre-charge sub-circuit comprises: a buffer resistor and a relay;

the buffer resistor is connected with the relay in parallel, and two ends of the buffer resistor after being connected in parallel are respectively used as two ends of the pre-charging sub-circuit;

the relay is controlled by the control unit.

12. The charging device for an electric vehicle according to claim 11, wherein a rated current of the relay is smaller than a preset current value.

13. The charging device of claim 10, wherein the main contactor is controlled by an external controller of the charging device;

the control unit is in communication connection with the external controller.

14. The charging device for an electric vehicle according to claim 10, wherein the bidirectional DC/DC conversion circuit comprises: the transformer, the primary circuit and the secondary circuit;

the direct current side of the primary side circuit is used as the primary side of the bidirectional DC/DC conversion circuit;

the alternating current side of the primary side circuit is connected with the primary side winding of the transformer;

the secondary winding of the transformer is connected with the alternating current side of the secondary circuit;

the direct current side of the secondary side circuit is used as the secondary side of the bidirectional DC/DC conversion circuit.

15. The charging device for the electric vehicle according to any one of claims 10 to 14, further comprising: a DC/DC circuit for realizing high-voltage to low-voltage conversion;

the first side of the DC/DC circuit is connected with the high-voltage side of the bidirectional DC/DC conversion circuit;

and the second side of the DC/DC circuit is used for connecting a low-voltage storage battery of the electric automobile.

16. The charging device for the electric vehicle according to any one of claims 10 to 14, further comprising: an AC/DC circuit;

the alternating current side of the AC/DC circuit is connected with an auxiliary winding of a transformer in the bidirectional DC/DC conversion circuit;

and the direct current side of the AC/DC circuit is used for connecting a low-voltage storage battery of the electric automobile.

17. An electric vehicle characterized in that its on-board power supply is the charging device of the electric vehicle according to any one of claims 10 to 16;

and the grounding end of the charging device is connected with the vehicle body ground and is connected with the charging control end of the vehicle control device in the electric vehicle and the charging control end of the external power supply equipment through the controllable switch.

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