Background
The charging conversion system of the new energy automobile is equipment for converting alternating current of a power grid into direct current and storing the direct current into a vehicle-mounted energy storage device, and is an important technology of the new energy automobile. Since the energy storage system may generate harmonic pollution to the power grid and may reduce the power factor of the whole system, the charging conversion system is required to have a harmonic suppression function and a rate factor correction function. In order to adapt to different working states of the battery, the voltage-current characteristics at two ends of the direct current side can be adjusted.
Conventionally, an on-vehicle charging system is formed by connecting a rectifying circuit, a power factor correction circuit, and a dc conversion circuit in sequence. Generally, an uncontrolled rectifier bridge circuit is selected as a rectifier circuit on the alternating current side; a group of power factor correction circuits with controllable switching tubes and inductors are inserted behind a rectifier bridge of rectification and rectification so as to achieve the effects of inhibiting harmonic waves and improving power factors; the DC conversion circuit on the DC side selects an isolation DC/DC circuit to regulate the output current voltage.
However, in practical applications, the following problems generally occur in the conventional vehicle-mounted charging conversion system.
Firstly, a rectifying circuit on an alternating current side is generally set to be an uncontrolled rectifying bridge structure, and 4 or more rectifying diodes are needed; when current flows through the rectifier diode, due to the volt-ampere characteristic of the semiconductor device, voltage drop can be generated at two ends of the diode, so that on-state loss is generated, and the overall operation efficiency of the system is reduced; in addition, the system needs to be directly connected to a power grid and has higher power level, so that the requirement on high current resistance of the rectifier diode is higher, and the diode with high current resistance has huge volume due to the limitation of the packaging process; in order to avoid the influence of the magnetic field generated by the alternating current on the stability of the system, the rectifying circuit needs to be designed separately, so that the volume of the system is further increased, and the design cost is higher.
Secondly, the power factor correction circuit needs to be connected with a power factor correction inductor, the inductor is a part of a main circuit, and the inductance of the inductor needs to meet certain design requirements. In general, the power factor correction inductor needs a large overcurrent area, so that the size of the power factor correction inductor is large; under the condition that the structure of the power factor correction circuit is fixed, the switching frequency of the circuit is usually a fixed value, so the design of the mode for improving the inductive reactance can only be realized by increasing the inductance, but the mode can increase the internal resistance of the inductance while increasing the inductive reactance, and the energy transmission loss is generated. Thus, the space utilization rate of the whole vehicle-mounted charging conversion system is seriously reduced.
In addition, a flyback direct-current converter is generally selected at the direct-current side, the converter is a Buck-Boost circuit, bidirectional flow of energy can be achieved, isolation between the alternating-current side and the direct-current side can be achieved, and the direct-current side direct-current charging circuit is suitable for charging batteries. However, the flyback dc converter has the disadvantages of complex structure, need to access a transformer, and small power level.
Finally, the energy storage element in the charging system is generally a lithium battery, and the energy storage device may have unstable variation under the condition of large current. Because the charging and discharging characteristics can not change suddenly, the control difficulty of the lithium battery is obviously increased when the lithium battery is connected or disconnected into a charging system and provides starting voltage for the motor, and higher requirements are provided for the design of a vehicle-mounted charging system.
Based on the above-mentioned problems of the existing vehicle-mounted charging conversion system, a new integrated vehicle-mounted charging conversion system is urgently needed.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a new energy vehicle integrated vehicle-mounted charging conversion system, including: the power factor correction circuit, the direct current conversion circuit, the alternating current source and the permanent magnet synchronous motor in the new energy automobile driving device; the power factor correction circuit comprises an alternating current end and a direct current end; the alternating current source and the stator three-phase inductance of the permanent magnet synchronous motor are connected with the alternating current end of the power factor correction circuit, and the direct current conversion circuit is connected with the direct current end of the power factor correction circuit; the power factor correction circuit is used for correcting a power factor and suppressing harmonic waves through a stator three-phase inductor of the permanent magnet synchronous motor, rectifying alternating current generated by an alternating current source into direct current and transmitting the direct current to the direct current conversion circuit, and the direct current conversion circuit is used for storing and releasing the direct current from the power correction circuit.
In addition, the preferred structure is that the power factor correction circuit is a controllable rectifier bridge circuit and comprises four bridge arms which are connected in parallel, the middle points of the four bridge arms are respectively named as M1-2, M3-4, M5-6 and M7-8, the middle points of the four bridge arms jointly form an alternating current end, two ends of the four bridge arms which are connected in parallel form a direct current end, one end taking the c pole in the bridge arm as the direct current end is taken as the anode of the power factor correction circuit, and one end taking the e pole in the bridge arm as the direct current end is taken as the cathode of the power factor correction circuit;
the bridge arm middle points M7-8, M1-2 and M3-4 are respectively connected with the phase-a inductor, the phase-b inductor and the phase-c inductor of the permanent magnet synchronous motor stator, and M7-8 between the bridge arm middle points M5-6 is connected with an alternating current source.
In addition, the four bridge arms preferably comprise two IGBT type switching tubes connected in series in the same direction, eight IGBT type switching tubes are provided in total and are respectively named as S1-S8, and a node between the two IGBI type switching tubes connected in series in the same direction is a bridge arm midpoint.
In addition, the power factor correction circuit preferably has a structure in which a freewheeling diode is connected in parallel with both ce terminals of the IGBT type switching tube in an inverse manner.
In addition, the dc conversion circuit preferably includes a battery, an inductor L, a first switching tube S9, a capacitor C, and a second switching tube S10, which are sequentially connected in series to form a loop; and a third switching tube S11 is connected in reverse parallel at two ends of a branch circuit formed by the first switching tube S9 and the capacitor C, the positive electrode of the capacitor C is the positive electrode of the direct current conversion circuit, the negative electrode of the battery is the negative electrode of the direct current conversion circuit, and the positive electrode and the negative electrode of the direct current conversion circuit are respectively connected with the positive electrode and the negative electrode of the power correction circuit.
In addition, the capacitor C is preferably a super capacitor.
In addition, it is preferable that the first switching tube, the second switching tube, and the third switching tube are all IGBT switching tubes, and freewheeling diodes are connected in parallel to the ends of the first switching tube, the second switching tube, and the third switching tube ce in an inverted manner.
Preferably, the power factor correction circuit further includes a control circuit and a drive circuit, the drive circuit drives the power factor correction circuit and the dc conversion circuit, and the control circuit transmits a drive signal to the drive circuit.
In addition, the drive circuit preferably includes a first drive circuit for driving the power factor correction circuit and a second drive circuit for driving the dc conversion circuit.
In addition, the driving signal is preferably a PWM signal, the driving circuit adjusts the PWM signal and transmits the adjusted PWM signal to the power factor correction circuit and the switching tube in the dc converter circuit, and the control circuit controls the switching tube in the power factor correction circuit and the switching tube in the dc converter circuit to be turned on or off according to the PWM signal.
By utilizing the new energy automobile integrated vehicle-mounted charging conversion system provided by the invention, an automobile driving system and the vehicle-mounted charging conversion system can be combined, a power factor correction inductor in the traditional vehicle-mounted charging conversion system is omitted, the space utilization rate is obviously improved, and in addition, the inductor in the permanent magnet synchronous motor is used as a power factor correction staggered inductor, so that the harmonic suppression capability on the alternating current side can be obviously improved.
To the accomplishment of the foregoing and related ends, one or more aspects of the invention comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Further, the present invention is intended to include all such aspects and their equivalents.
Detailed Description
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details.
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a new energy vehicle integrated vehicle-mounted charging conversion system according to the invention, and fig. 2 is a block schematic diagram of the new energy vehicle integrated vehicle-mounted charging conversion system according to the invention.
With reference to fig. 1 and 2, an integrated vehicle-mounted charging conversion system for a new energy vehicle includes: the system comprises a power factor correction circuit 1, a direct current conversion circuit 2, an alternating current source 4 and a permanent magnet synchronous motor 3 in a new energy automobile driving device; the power factor correction circuit 1 comprises an alternating current end and a direct current end; the alternating current source 4 and the stator three-phase inductance of the permanent magnet synchronous motor 3 are connected with the alternating current end of the power factor correction circuit 1, and the direct current conversion circuit 2 is connected with the direct current end of the power factor correction circuit 1; the power factor correction circuit 1 is further configured to rectify alternating current generated by the alternating current source 4 into direct current and transmit the direct current to the direct current conversion circuit 2, and the direct current conversion circuit 2 is configured to store and release the direct current from the power correction circuit.
The new energy automobile integrated vehicle-mounted charging conversion system provided by the invention is designed into a brand-new topological structure, integrates a transmission system and a charging conversion system of an electric automobile, and connects a three-phase inductor in a stator of a permanent magnet synchronous motor 3 in the transmission system of the electric automobile with an alternating current end of a power factor correction circuit 1 to be used as a power factor correction inductor, so that the mode can not only save the work of an additional inductor and related equipment needed by the alternating current end of the power factor correction circuit 1, but also reduce the volume of the power factor correction circuit 1 and obviously improve the space utilization rate of the charging conversion system.
Specifically, the power factor correction circuit 1 is a controllable rectifier bridge circuit, and comprises four bridge arms connected in parallel and named as a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm respectively, the midpoints of the four bridge arms are named as M1-2, M3-4, M5-6 and M7-8 respectively, the midpoints of the four bridge arms jointly form an alternating current end, two ends of the four bridge arms connected in parallel form a direct current end, one end with the c pole in the bridge arm as the direct current end is the anode of the power factor correction circuit 1, and one end with the e pole in the bridge arm as the direct current end is the cathode of the power factor correction circuit 1; the bridge arm middle points M7-8, M1-2 and M3-4 are respectively connected with the phase a inductance La, the phase b inductance Lb and the phase c inductance Lc of the stator of the permanent magnet synchronous motor 3, and M7-8 between the bridge arm middle points M5-6 is connected with the alternating current source 4.
The charging conversion system provided by the invention designs the power factor correction circuit 1 into a controllable rectifier bridge with a totem-pole structure, and inserts the three-phase inductance of the stator of the permanent magnet synchronous motor 3 into the controllable rectifier bridge to form an interleaved structure, so that the charging conversion system has obvious harmonic suppression effect, in addition, as the power factor correction circuit 1 is of the totem-pole structure and also has the rectifying effect, the alternating current in the alternating current source 4 can be rectified into direct current only by inserting the alternating current source 4 into the middle point bridge arms M5-6 between the bridge arms M7-8 in the using process, the power factor correction circuit 1 can be directly connected with the alternating current source 4 in the mode, the rectifying work of the alternating current source 4 by an additional rectifying circuit is saved, and the space of the charging conversion system is further saved.
More specifically, the four bridge arms respectively comprise two IGBT type switching tubes which are connected in series in the same direction, and eight IGBT type switching tubes are total and are respectively named as S1-S8; the first bridge arm comprises S1 and S2, the second bridge arm comprises S3 and S4, the third bridge arm comprises S5 and S6, the fourth bridge arm comprises S7 and S8, and a node between two IGBI-type switching tubes which are connected in series in the same direction is named as a bridge arm midpoint; the IGBT is an insulated gate bipolar transistor, belongs to a high-power fully-controlled switch tube, and selects the IGBT type switch tube because the power of a charging conversion system is higher and the system is better controlled.
In addition, in order to make the current formed after rectification continuous and prevent the IGBT type switching tube from being burnt out in the whole working process of the system, a freewheeling diode is reversely connected in parallel at two ends of the CE of the IGBT type switching tube in the power factor correction circuit 1.
In a preferred embodiment of the present invention, the dc conversion circuit 2 includes a battery, an inductor L, a first switch tube S9, a capacitor C, and a second switch tube S10, which are sequentially connected in series to form a loop; and a third switching tube S11 is connected in anti-parallel at two ends of a branch formed by the first switching tube S9 and a capacitor C, the capacitor C is a polar capacitor, the positive electrode of the capacitor C is the positive electrode of the direct current conversion circuit 2, the battery is a lithium ion battery, the negative electrode of the battery is the negative electrode of the direct current conversion circuit 2, and the positive electrode and the negative electrode of the direct current conversion circuit 2 are respectively connected with the positive electrode and the negative electrode of the power correction circuit.
Compared with the traditional direct current conversion circuit, the direct current conversion circuit 2 with the novel structure can avoid the phenomenon that components are burnt out under the direct connection condition of an alternating current side bridge arm in a short time when the vehicle-mounted charging conversion system works, avoids dead zone compensation in switch tube control, and reduces the switching loss of the switch tube.
Specifically, the first switch tube, the second switch tube and the third switch tube are all IGBT type switch tubes, and freewheeling diodes are connected in parallel at two ends of the first switch tube, the second switch tube and the third switch tube ce.
More specifically, the capacitor C is a super capacitor, which is also called an electrochemical capacitor, and is an electrochemical element developed from the seventh and eighties of the last century and storing energy through a polarized electrolyte, and unlike a traditional chemical power source, the capacitor C is a power source with special performance between a traditional capacitor and a battery, and mainly stores electric energy by electric double layers and redox pseudocapacitance charges. But no chemical reaction occurs in the process of energy storage, and the energy storage process is reversible, and the super capacitor can be repeatedly charged and discharged for tens of thousands of times. According to the invention, the super capacitor is arranged on the direct current side as an additional energy storage device, so that the rapid transfer of the energy of the whole system can be realized, and the charge-discharge transient performance of the whole circuit is obviously improved.
In addition, in an embodiment of the present invention, in order to facilitate control of the new energy vehicle integrated vehicle-mounted charging conversion system, the charging conversion system further includes a control circuit 6 and a driving circuit 5, the driving circuit 5 is configured to drive the power factor correction circuit 1 and the dc conversion circuit 2, and the control circuit 6 is configured to send a driving signal to the driving circuit 5.
Specifically, the driving circuit 5 includes a first driving circuit 5 and a second driving circuit 5, the first driving circuit 5 is used for driving the power factor correction circuit 1, and the second driving circuit 5 is used for driving the dc conversion circuit 2.
More specifically, the driving signal is a PWM signal, the driving circuit 5 is configured to adjust the PWM signal and transmit the adjusted PWM signal to the power factor correction circuit 1 and the switching tubes in the dc conversion circuit 2, the control circuit 6 controls the on/off of the switching tubes in the power factor correction circuit 1 and the dc conversion circuit 2 through the PWM signal, and the adjustment of the driving circuit 5 mainly includes isolating the PWM signal from the ac terminal and amplifying the signal.
For a better understanding of the present invention, the following detailed description is provided to illustrate the working principles of the present invention.
1) In the charging mode, the power factor correction 1 circuit can be used as a rectifying circuit, and the switching tubes S1-S6 work, wherein the switching tubes S1-S4 are alternately conducted according to the control duty ratio of the power factor correction circuit 1, S1 and S2 are complementarily conducted, S3 and S4 are complementarily conducted, S1 and S3 are conducted at 180 degrees alternately, and S2 and S4 are conducted at 180 degrees alternately; in addition, the switching tubes S5 and S6 are alternately turned on according to the operating phase of the ac source.
2) In a charging mode, the three-phase inductance of the stator of the permanent magnet synchronous motor 3 is connected into the power factor correction circuit 1 to serve as a power factor correction inductance, alternating current flows into two staggered inductances Lb and Lc through the inductance La, and the inductances Lb and Lc serve as the staggered power factor correction inductances to play a role in reducing harmonic content.
3) In the charging mode, the switching tubes S9-S11 of the dc converter circuit 2 are operated, wherein the switching tubes S11 and S9-S10 are complementarily turned on. In this mode, the dc conversion circuit 2 is a Buck circuit. When any bridge arm switching tube of the alternating-current side power factor correction circuit 1 is switched to be in a working state, the switching tube S11 is controlled by the through duty ratio M, and the working states of S9-S10 are opposite to the working state of S11; when the switch tube in the AC side is in the normal conducting state, the switch tube S11 is controlled by the conducting duty ratio D, and the working state of S9-S10 is opposite to the working state of S11. The alternating current source 4 charges the super capacitor and the battery, and the super capacitor charges the battery.
4) In the discharging mode, the power factor correction circuit 1 can be used as an inverter circuit, and the switching tubes S1-S6 work, wherein the switching tubes S1-S4 alternately invert according to the phase of the power grid, wherein S1 and S2 are complementarily conducted, S3 and S4 are complementarily conducted, S1 and S3 are simultaneously conducted, and S2 and S4 are simultaneously conducted; the switching tubes S5 and S6 are alternately turned on according to the operating phase of the ac source 4.
5) In the discharging mode, the three-phase inductance of the stator of the permanent magnet synchronous motor 3 is connected to the power factor correction circuit 1 and serves as a rectifying and filtering inductance. Alternating current respectively and alternately forms an L-shaped filter with Lb and Lc through the inductor La to play a role in filtering harmonic waves.
6) In the discharging mode, the switching tubes S9-S11 of the dc converter circuit 2 are operated, wherein the switching tubes S11 and S9-S10 are complementarily turned on. In this mode, the dc conversion circuit 2 is a Boost circuit. When any bridge arm switching tube of the alternating-current side power factor correction circuit 1 is switched to be in a working state, the switching tube S11 is controlled by the through duty ratio M, and the working states of S9-S10 are opposite to the working state of S11; when the AC side switch tube is in a normal conducting state, the switch tube S11 is controlled by the conducting duty ratio D, and the working state of S9-S10 is opposite to the working state of S9; the battery discharges to the super capacitor and the ac source 6, and the super capacitor discharges to the ac source 6.
7) In the motor driving mode, the power factor correction circuit 1 operates the switching tubes S1-S4 and S7-S8, wherein the switching tubes S1 and S2, S3 and S4, and S7 and S8 respectively form a control bridge, and flux linkage control is performed on the inductors La, Lb and Lc according to a vector control method, so as to realize driving of the permanent magnet synchronous motor 3.
8) In the motor driving mode, the switching tubes S9-S11 of the dc converter circuit 2 are operated, wherein the switching tubes S11 and S9-S10 are complementarily turned on. In this mode, the dc conversion circuit 2 is a Boost circuit. When the switching tube of any bridge arm is switched to work state, the switching tube S11 is controlled by the through duty ratio M, and the work state of S9-S10 is opposite to the work state of S9; when the alternating current side is in a normal conducting state, the switching tube S11 is controlled by the conducting duty ratio D, and the working state of S9-S10 is opposite to the working state of S11; when the control bridge enters the zero vector state, S11 is turned off, and the working states S9-S10 are opposite to the working state S11. The battery and the super capacitor supply power for the motor, and the battery discharges to the super capacitor.
The Buck circuit is a voltage-reducing direct current conversion circuit, and the output voltage is lower than the input voltage; the Boost circuit is a Boost direct current conversion circuit, and the output voltage is higher than the input voltage; the two similar periodic signals are staggered and work with a certain phase difference at a uniform moment; the interleaving circuit is a circuit which utilizes two currents to be interleaved and connected in parallel to reduce harmonic waves; the straight-through is the condition that two devices of a group of bridge arms are simultaneously conducted, and for a general circuit, the straight-through state is a short-circuit state and needs to be avoided; the dead zone is a method for avoiding straight-through, and all devices of a bridge arm are turned off before the bridge arm is switched to a working state. This approach can adversely affect the system and generally requires compensation in control; the through duty ratio refers to the duty ratio of a control signal under the through condition; the on duty cycle refers to the duty cycle of the control signal under the non-direct condition.
Therefore, the integrated vehicle-mounted charging conversion system for the new energy automobile has the following advantages:
1. the vehicle-mounted charging system is combined with the permanent magnet synchronous motor in the automobile driving system, and the inductor in the stator of the permanent magnet synchronous motor is used as a power factor correction inductor, so that the size of the whole vehicle-mounted charging conversion system can be obviously reduced;
2. the power factor correction circuit is designed into a totem-pole controllable rectifier bridge structure, so that the work of adding a rectifier circuit on the alternating current side can be omitted, and the size of a vehicle-mounted charging conversion system is further reduced;
3. the alternating current side uses the inductor of the permanent magnet synchronous motor to form an interleaved power factor correction circuit, and compared with the traditional external inductor, the harmonic suppression capability can be obviously improved;
4. by designing a novel direct current conversion circuit, the use of a coupling element of a flyback circuit is omitted, and a super capacitor is additionally arranged to serve as an energy storage device, so that the energy amount can flow rapidly, and the transient performance of the circuit is improved;
5. the power factor correction circuit can be used as a permanent magnet synchronous motor driving circuit, and provides high starting voltage for the permanent magnet synchronous motor and controls the permanent magnet synchronous motor;
6. the direct current conversion circuit with the novel structure can avoid the phenomenon that components are burnt out when an alternating current side bridge arm is in a direct connection condition in a short time, avoids dead zone compensation on the control of the switch tube, and reduces the switching loss of the switch tube.
The new energy vehicle-integrated on-vehicle charging conversion system according to the present invention is described above by way of example with reference to fig. 1 and 2. However, it should be understood by those skilled in the art that various modifications may be made to the new energy vehicle integrated vehicle charging conversion system provided by the invention without departing from the scope of the invention. Therefore, the scope of the present invention should be determined by the contents of the appended claims.