Power conversion system for a vehicle and method of controlling the same

Abstract

The present application relates to a power conversion system for a vehicle and a control method thereof. A power conversion system includes: an AC-DC conversion circuit that converts AC charging power into DC power; a motor including a plurality of coils, one end of each coil being connected to a neutral point; a first switching device that selectively allows or blocks supply of output power from the AC-DC conversion circuit to the neutral point; a converter including a plurality of motor connection terminals connected to the other ends of the coils of the motor, a DC connection terminal including a positive terminal and a negative terminal, and a plurality of switching elements forming an electrical connection between the DC connection terminal and the plurality of motor connection terminals; a battery connected to the DC connection terminal of the converter; and a controller that controls operations of the AC-DC conversion circuit, the first switching device, and the converter depending on whether the battery is being charged.

Description

Technical Field

[0001] This disclosure relates in its entirety to a power conversion system for vehicles and a control method thereof. Background Technology

[0002] The statements in this section are provided only as background information in connection with this disclosure and should not constitute prior art.

[0003] Typically, electric vehicles or plug-in hybrid vehicles can use electricity provided by an external charging device to charge their batteries and generate propulsion by using the electrical energy stored in the charged batteries to actuate the motors.

[0004] Such vehicles are equipped with an on-board charger (OBC) to convert alternating current (AC) from an external power source into direct current (DC) with an appropriate voltage level and to supply DC power to the battery located within the vehicle for charging. Additionally, the vehicle may be equipped with a low-voltage DC-DC converter (LDC) to convert the high voltage output from the battery to power the motor into a low voltage used by the vehicle's electrical components.

[0005] As mentioned above, vehicles are equipped with various power conversion devices used for various purposes. However, we have found that some devices only operate in designated vehicle operating modes and are inoperable in other operating modes. For example, devices that convert AC power supplied from an external power source to DC power (using DC power to charge the battery) and onboard chargers installed in the vehicle are completely inoperable in the vehicle's driving mode.

[0006] Accordingly, we have found that when the power unit used for vehicle operation shares some components with the on-board charger or is integrated into a single structure, the number of components used to build the entire power conversion system can be reduced, thereby reducing the weight and size of the power conversion system.

[0007] The foregoing is intended only to help in understanding the background of this disclosure and is not intended to imply that this disclosure falls within the scope of the relevant technical fields known to those skilled in the art. Summary of the Invention

[0008] This disclosure proposes a power conversion system and its control method, wherein an on-board charger and a low-voltage DC converter that converts the high voltage of a battery into a low voltage are integrated together, thereby enabling a reduction in the number of components and a reduction in the weight and size of the power conversion device.

[0009] In one aspect of this disclosure, a power conversion system for a vehicle may include: an AC-DC conversion circuit that converts AC charging power into DC power; a motor including a plurality of coils each having a first terminal respectively connected to a neutral point; a first switching device that selectively allows or prevents the supply of output power from the AC-DC conversion circuit to the neutral point; a converter including: a plurality of motor connection terminals respectively connected to second terminals of the plurality of coils of the motor, a DC connection terminal including a positive terminal and a negative terminal, and a plurality of switching elements forming an electrical connection between the DC connection terminals and the plurality of motor connection terminals; a battery connected to the DC connection terminal of the converter; and a controller that controls the operation of the AC-DC conversion circuit, the first switching device, and the converter based on whether the battery is being charged.

[0010] According to another embodiment, the AC-DC conversion circuit may include: a first bridging circuit including a plurality of switching elements forming the bridging circuit and configured to receive AC charging power from an external AC charging device; a transformer including: a first coil subjected to an AC voltage generated by a short circuit or open circuit of the switching elements in the first bridging circuit, and a second coil electromagnetically coupled to the first coil and transforming the AC voltage applied to the first coil at a predetermined ratio; and a second bridging circuit including a plurality of switching elements, the second bridging circuit rectifying the output voltage of the second coil or converting an input DC voltage into an AC voltage and applying the converted AC voltage to the second coil.

[0011] According to another embodiment, the first bridging circuit may include: a first input terminal and a second input terminal, with a voltage of AC charging power applied between the first input terminal and the second input terminal; a first switching element and a second switching element, each having a first terminal respectively connected to the first input terminal; a third switching element connected to the second terminal of the first switching element; and a fourth switching element connected between the second terminal of the second switching element and the first terminal of the third switching element, wherein the two ends of the first coil of the transformer may be respectively connected to the connection nodes of the second input terminal and the third and fourth switching elements.

[0012] According to one embodiment, the second bridge circuit may include: a fifth switching element; a sixth switching element having a first terminal connected to a first terminal of the fifth switching element; a seventh switching element having a first terminal connected to a second terminal of the fifth switching element; and an eighth switching element connected between the second terminal of the sixth switching element and the second terminal of the seventh switching element; a second coil of a transformer is connected to the connection node of the fifth and sixth switching elements and the connection node of the seventh and eighth switching elements; and the voltage applied between the connection node of the fifth and seventh switching elements and the connection node of the sixth and eighth switching elements is the output voltage of the AC-DC conversion circuit.

[0013] In one embodiment, the power conversion system may further include a DC capacitor connected to the output terminal of a second bridging circuit.

[0014] According to another embodiment, the power conversion system may further include: a DC capacitor having two ends connected to connection nodes of the fifth and seventh switching elements and connection nodes of the sixth and eighth switching elements, respectively.

[0015] According to one form, in a charging mode in which the battery is charged using AC charging power, the controller can control the output voltage of the AC-DC conversion circuit applied to the neutral point by short-circuiting the first switching device, and control multiple switching elements such that the circuit, including the multiple switching elements in the coil and converter, operates as a boost converter.

[0016] According to another form, the controller can control the duty cycle of the switching element connected to the negative terminal among the multiple switching elements in the converter to boost the charging voltage applied to the DC connection terminal, thereby applying the boosted voltage to the battery.

[0017] According to another embodiment, the transformer may further include: a third coil, electromagnetically connected to the first or second coil, which outputs the voltage of the first or second coil by transforming the voltage at a predetermined ratio; and a low-voltage converter, controlled by a controller, to convert the voltage output from the third coil into a predetermined voltage lower than the voltage of the battery.

[0018] According to one embodiment, the low-voltage converter may include: a rectifier for rectifying the voltage output from a third coil; a smoother for smoothing the voltage rectified by the rectifier; and a voltage converter for converting the smoothed voltage into a predetermined voltage.

[0019] According to another embodiment, the rectifier may include: a first diode having a cathode connected to a first end of a third coil; and a second diode having a cathode connected to a second end of the third coil. The smoother may include: a capacitor having a first end connected to the midpoint of the third coil; and a smoothing switching element having a first end connected to a second end of the capacitor and a second end commonly connected to the anodes of the first and second diodes. The voltage converter may be a buck converter, comprising: a buck switching element having a first end connected to the second end of the capacitor in the smoother; a third diode having a cathode connected to the second end of the buck switching element and an anode connected to the second end of the smoothing switching element; and an inductor having a end connected to the cathode of the third diode.

[0020] According to one embodiment, the power conversion system may further include: a second switching device connected between the positive terminal of the converter and the output terminal of the AC-DC conversion circuit.

[0021] According to another form, the second switching device may be: an active switch, the short circuit or open circuit of which is determined by a controller; or a diode having an anode connected to the positive terminal of the converter and a cathode connected to the output terminal of the AC-DC conversion circuit.

[0022] According to other forms, in a charging mode in which the battery is charged using AC charging power, the controller may: open the second switching device; apply the output voltage of the AC-DC conversion circuit to the neutral point by short-circuiting the first switching device; control multiple switching elements in the converter to operate as a boost converter through a circuit formed by multiple switching elements and multiple coils; and control the low-voltage converter to convert the voltage output from the third coil through the electrical coupling between the first coil and the third coil into a predetermined voltage lower than the battery voltage.

[0023] According to one form, in a travel mode in which the motor is actuated, the controller can: open a first switching device; apply the battery voltage to a second bridge circuit by short-circuiting a second switching device; convert the battery voltage by controlling the state of the switching elements in the second bridge circuit to apply an AC voltage to a second coil; control a plurality of switching elements in a converter to operate a circuit formed by the plurality of switching elements and the plurality of coils as a boost converter; and control a low-voltage converter to convert the voltage converted and output from the third coil through electrical coupling between the second and third coils into a predetermined voltage lower than the battery voltage.

[0024] According to another form, in the travel mode where the motor is actuated, the controller can open the switching element in the first bridge circuit.

[0025] According to another aspect of this disclosure, a control method for the aforementioned power conversion system for a vehicle is provided. The method may include: determining, via a controller, whether the vehicle is in a charging mode in which the battery is charged using AC charging power or in a driving mode in which the motor is actuated; when it is determined that the vehicle is in charging mode, short-circuiting a first switching device, opening a second switching device, applying the output voltage of the AC-DC circuit to a neutral point, and controlling a plurality of switching elements in a converter such that the circuit formed by the plurality of coils and the plurality of switching elements in the converter operates as a boost converter; controlling a low-voltage converter to convert the voltage output from the third coil through electrical coupling between the first and third coils into a voltage higher than that of the battery. The system applies a predetermined voltage lower than the battery voltage; and when the vehicle is determined to be in driving mode, the first switching device is opened, the second switching device is short-circuited to apply the battery voltage to the second bridge circuit, the battery voltage is converted by controlling the state of the switching elements in the second bridge circuit to apply AC voltage to the second coil, multiple switching elements in the converter are controlled to make the circuit formed by the coil and multiple switching elements operate as a boost converter, and the low-voltage converter is controlled to convert the voltage converted and output from the third coil through the electrical coupling between the second coil and the third coil to a predetermined voltage lower than the battery voltage.

[0026] In the various forms of power conversion systems and control methods for vehicles according to this disclosure, unlike vehicle power conversion systems in related technical fields, multiple components such as power factor correction circuits or isolation converters located in the on-board charger can be omitted. The second-side bridge circuit of the AC-DC converter can be shared with the first side of the low-voltage converter to reduce the number of components and reduce the size and weight of the system. Accordingly, due to the reduced manufacturing cost and the reduced number of components, the power conversion system in the vehicle can be easily packaged and its mass production can be facilitated.

[0027] The objectives of this disclosure are not limited to those described above, and other objectives not explicitly disclosed herein will be clearly understood by those skilled in the art from the description provided below.

[0028] Further areas of application will become apparent from the description provided herein. It should be understood that the description and specific embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0029] To facilitate understanding of this disclosure, various forms thereof, as given by way of embodiments, will now be described with reference to the accompanying drawings, in which:

[0030] Figure 1 This is a circuit diagram showing the power conversion system used in a vehicle;

[0031] Figure 2 This is a circuit diagram showing a power conversion system for a vehicle; and

[0032] Figure 3 This is a flowchart illustrating a control method for a power conversion system used in a vehicle.

[0033] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way. Detailed Implementation

[0034] The following description is exemplary in nature and is not intended to limit this disclosure, its application, or its use. It should be understood that throughout the drawings, corresponding reference numerals denote similar or corresponding parts and features.

[0035] The following sections will describe in detail various forms of power conversion systems and their control methods with reference to the accompanying drawings.

[0036] Figure 1 This is a circuit diagram illustrating one form of power conversion system for a vehicle according to the present disclosure.

[0037] refer to Figure 1 The power conversion system for a vehicle includes: an AC-DC conversion circuit 100, a motor 500, a first switching device R1, a converter 600, a battery 20, and a controller 700. The AC-DC conversion circuit 100 converts AC charging power AC_In into DC power. The motor 500 includes multiple coils, one end of which is connected to a single point, namely, the neutral point N. The first switching device R1 selectively allows or prevents the supply of output power from the AC-DC conversion circuit to the neutral point N. The converter 600 includes: multiple motor connection terminals 610a, 610b, and 610c, respectively connected to the other end of the coils of the motor 500; DC connection terminals 610p and 610n, including a positive terminal 610p and a negative terminal 610n; and multiple switching elements forming electrical connections between the DC connection terminals 610p and 610n and the multiple motor connection terminals 610a, 610b, and 610c. Battery 20 is connected to DC connection terminals 610p and 610n of converter 600. Controller 700 controls the operation of AC-DC conversion circuit 100, first switching device R1, and converter 600 based on whether battery 20 is being charged.

[0038] Furthermore, the power conversion system for a vehicle according to the form of this disclosure may further include: a DC capacitor C1 for forming a DC voltage on the DC output side of the AC-DC conversion circuit 100; a second switching device D1 for determining the electrical connection state between the positive terminal 610p of the converter 600 and the AC-DC conversion circuit 100; and a low-voltage converter 400.

[0039] The power conversion system for a vehicle is a system that can use an AC-DC conversion circuit 100 to convert an AC charging voltage input from an external power source into a DC voltage and then charge the battery 20 by using a motor actuation system including a motor 500 and a converter 600 as the power conversion circuit, thereby removing the structure including a power factor correction circuit and a DC-DC converter provided in the on-board charger of the relevant technical field.

[0040] Furthermore, the power conversion system is a system in which the second bridge circuit 120 of the AC-DC conversion circuit 100 can replace the first side of a low-voltage converter in the relevant technical field that is separately provided with the first bridge circuit and the second bridge circuit, in order to convert the voltage of the high-voltage battery 20 used to actuate the motor into a low voltage used to drive the electrical components of the vehicle.

[0041] As described above, compared with power conversion systems in related technical fields, in the power conversion system for vehicles according to the form of this disclosure, multiple components can be omitted or shared, thereby reducing the number of components and reducing the size and weight of the system.

[0042] While providing electrical insulation between the battery 20 in the vehicle and the AC charging device 10, the AC-DC conversion circuit 100 uses multiple switching elements and transformers (i.e., the input and output terminals of the AC-DC conversion circuit 100) to convert the AC voltage supplied from the external AC charging device 10 into DC voltage.

[0043] AC-DC conversion circuit 100 includes a first bridging circuit 110, a transformer 200, and a second bridging circuit 120. The first bridging circuit 110 includes multiple switching elements forming the bridging circuit, applying AC charging power from an external AC charging device 10 to the first bridging circuit 110. The transformer 200 includes: a first coil 210, which is subjected to an AC voltage generated by a short circuit or open circuit through the switching elements in the first bridging circuit 110; and a second coil N2, electromagnetically coupled to the first coil 210, converting the AC voltage applied to the first coil 210 at a predetermined ratio. The second bridging circuit 120 includes multiple switching elements to rectify the output voltage of the second coil N2 or convert the input DC voltage into AC voltage, and applies the converted AC voltage to the second coil N2.

[0044] More specifically, the first bridging circuit 110 may include: a first input terminal 111 and a second input terminal 112, with an AC charging voltage applied between the first input terminal 111 and the second input terminal 112; a first switching element Q1 and a second switching element Q2, with one terminal of each switching element connected to the first input terminal 111; a third switching element Q3 connected to the other terminal of the first switching element Q1; and a fourth switching element Q4 connected between the other terminal of the second switching element Q2 and the other terminal of the third switching element Q3. The two ends of the first coil 210 of the transformer 200 may be connected to the connection nodes of the second input terminal 112 and the third switching element Q3 and the fourth switching element Q4, respectively.

[0045] The second bridging circuit 120 may include: a fifth switching element Q5; a sixth switching element Q6 having a terminal connected to one terminal of the fifth switching element Q5; a seventh switching element Q7 having a terminal connected to the other terminal of the fifth switching element Q5; and an eighth switching element Q8 connected between the other terminal of the sixth switching element Q6 and the other terminal of the seventh switching element Q7. The two ends of the second coil 220 of the transformer 200 may be connected to the connection nodes of the fifth switching element Q5 and the sixth switching element Q6 and the seventh switching element Q7 and the eighth switching element Q8, respectively. Furthermore, the voltage applied between the connection node 121 of the fifth switching element Q5 and the seventh switching element Q7 and the connection node 122 of the sixth switching element Q6 and the eighth switching element Q8 may be the output voltage of the AC-DC conversion circuit. Therefore, the two ends of the DC capacitor C1 used to form the DC voltage may be connected to the connection node 121 of the fifth switching element Q5 and the seventh switching element Q7 and the connection node 122 of the sixth switching element Q6 and the eighth switching element Q8, respectively.

[0046] In the vehicle driving mode as described below, the connection node 121 of the fifth switching element Q5 and the seventh switching element Q7 and the connection node 122 of the sixth switching element Q6 and the eighth switching element Q8 can be an input terminal that receives input voltage from the battery 20.

[0047] Motor 500 is an electrically driven rotating machine that generates torque in response to drive power supplied to it from battery 20 via converter 600. Typically, motor 500 can operate by receiving multiple corresponding AC power supplies from converter 600. In a vehicle driving mode where torque is generated by actuating motor 500, converter 600 supplies different phases of AC power to the phases of motor 500 respectively by performing pulse width modulation (PWM) on switching elements Q9 to Q14 therein. Typically, as... Figure 1As shown, the motor 500 can be represented as a structure comprising multiple coils, each corresponding to a plurality of others. One end of each corresponding coil is electrically connected to each other to provide a Y-phase open structure. Here, the point where the corresponding coils in the motor 500 are connected to each other is called the neutral point N.

[0048] According to one form of this disclosure, in a charging mode where the battery 20 is supplied with charging power received from an external power source after conversion, the DC output voltage of the AC-DC conversion circuit 100 can be applied to the neutral point N of the motor 500. In a traveling mode where the motor 500 is actuated, since the neutral point N of the motor 500 must be disconnected from other power conversion components, a first switching device R1 can be provided that can selectively allow or prevent the supply of output power from the AC-DC conversion circuit to the neutral point N.

[0049] The controller 700 can control the state (short circuit or open circuit) of the first switching device R1. The first switching device R1 can be implemented as various switching components such as relays or semiconductor switches, and its state can be controlled by external control signals.

[0050] The converter 600 has DC connection terminals including a positive terminal 610p and a negative terminal 610n respectively connected to the two terminals of the battery 20, and three legs connected between the parallel DC connection terminals. Two switching elements (i.e., two switching elements Q9 to Q14) are connected in series to the respective legs. The connection nodes of the switching elements connected in series to the legs are multiple motor connection terminals 610a, 610b, and 610c respectively connected to the phases of the motor 500.

[0051] Typically, while the vehicle is in motion, the converter 600 can convert the DC power stored in the battery 20 into multiple phases of AC current and supply multiple phases of AC current to the phases of the motor 500 respectively.

[0052] As described above, the connection nodes of switching elements Q9 and Q10, Q11 and Q12, and Q13 and Q14 included in the motor legs can be connected to the corresponding coils of the motor 500 via motor connection terminals 610a, 610b, and 610c. Regarding this circuit connection structure, the two switching elements included in each leg of the converter 600 and a single coil in the motor 500 (with one end of the single coil connected to the connection node of the two switching elements) can form a boost DC-DC converter topology.

[0053] When energy flow is directed from the neutral point N of the motor 500 to the DC connection terminals 610p and 610n of the converter 600, the circuit structure including the switching elements of the converter 600 and the coils of the motor 500 can form a boost DC-DC converter to control the duty cycle of the switching elements Q10, Q12, and Q14 connected to the bottom phase of the negative terminal 610n. Since the three-phase converter 600 has a total of three legs, a structure is provided in which the boost DC-DC converter is connected in parallel between the DC connection terminals 610p and 610n of the converter 600 and the neutral point N of the motor 500.

[0054] In the charging mode in which the battery 20 is charged, before supplying voltage to the battery 20, the controller 700 can boost the voltage output from the AC-DC conversion circuit 100 by controlling the duty cycle of the switching elements Q10, Q12 and Q14 connected to the bottom phase of the negative terminal 610n in the circuit structure including the switching elements of the converter 600 and the coil of the motor 500.

[0055] The transformer 200 may further include a third coil 230, which is electromagnetically coupled to either the first coil 210 or the second coil 220. The third coil 230 may be included in the low-voltage converter 400. That is, the third coil 230 can output the voltage of the first coil 210 by inducing a voltage at the turns ratio between the first coil 210 and the third coil 230 through electromagnetic coupling with the first coil 210, or it can output the voltage of the second coil 220 by inducing a voltage at the turns ratio between the second coil 220 and the third coil 230 through electromagnetic coupling with both the second coil 220 and the third coil 230.

[0056] The low-voltage converter 400 can output a voltage induced by the third coil 230 by converting the voltage to a suitable order of magnitude. The output voltage of the low-voltage converter 400 can have an order of magnitude corresponding to the electrical power of the vehicle's electrical components. The output terminals of the low-voltage converter 400 can be connected to the electrical components or to an auxiliary battery 30 with a voltage corresponding to the order of magnitude of the electrical power of the vehicle's electrical components. The output voltage of the low-voltage converter 400 can be used to charge the auxiliary battery 30.

[0057] The low-voltage converter 400 may include a rectifier, a smoother, and a voltage converter.

[0058] The rectifier may include: a first diode D2 having a cathode connected to one end of the third coil 230; and a second diode D3 having a cathode connected to the other end of the third coil 230.

[0059] The smoother may include: a capacitor C2 having one end connected to the midpoint of the third coil 230; and a smoothing switching element Q15 having one end connected to the other end of the capacitor C2 and the other end connected to the anode of the first diode D2 and the second diode D3.

[0060] The voltage converter can be implemented as a buck converter, comprising: a buck switching element Q16 having one end connected to the other end of a capacitor C2 of a smoother; a third diode D4 having a cathode connected to the other end of the buck switching element Q16 and an anode connected to the other end of a smoothing switching element Q15; and an inductor Lo having one end connected to the cathode of the third diode D4.

[0061] According to one embodiment of this disclosure, in the vehicle's driving mode, the second bridge circuit 120 in the AC-DC conversion circuit 100 can convert the DC voltage of the battery 20 into an AC voltage, which is then applied to the second coil 220 of the transformer 200. Furthermore, the voltage can be output to the third coil 230 via electromagnetic induction between the second coil 220 and the third coil 230. Therefore, the low-voltage converter 400 can charge the auxiliary battery 30 or provide power to electrical components. In addition, in the charging mode, before applying an output voltage to the battery 20, the output voltage of the second bridge circuit 120 must be boosted by a boost converter including the coils of the motor 500 and the converter 600, rather than directly applying the output voltage to the battery 20.

[0062] Therefore, it is desirable that there is a second switching device D1 between the battery 20 and the second bridge circuit 120, which can determine the electrical connection status between the battery 20 and the second bridge circuit 120.

[0063] exist Figure 1 In the illustrated form, the switching device D1 disposed between the battery 20 and the second bridge circuit 120 can be implemented as a diode D1 having an anode connected to the battery 20 and a cathode connected to the second bridge circuit 120. More specifically, the anode of the diode D1 can be connected to the positive terminal 610p of the DC connection terminal of the converter 600, while the cathode of the diode D1 can be connected to the output terminal of the second bridge circuit 12, i.e., the connection node 121 of the fifth switching element Q5 and the seventh switching element Q7.

[0064] Figure 2 This is a circuit diagram illustrating another form of power conversion system according to this disclosure.

[0065] exist Figure 2In the illustrated configuration, an active switch R2 can be used as a switching device between the battery 20 and the second bridge circuit 120. The two ends of the active switch R2 are connected to the positive terminal of the battery 20 and the second bridge circuit 120, allowing the controller 700 to control the open or short circuit state of the active switch R2. The active switch R2 can be implemented as a device known in the art, such as a relay or a semiconductor switch, and its short or open circuit state can be controlled by an external control signal.

[0066] The controller 700 can appropriately control the aforementioned components according to the vehicle's state (i.e., whether the vehicle is in driving mode or charging mode) to convert AC charging power supplied from an external power source into DC power to charge the battery 20, or to appropriately convert the order of magnitude of the voltage of the battery 20 applied to the auxiliary battery 30 or electrical components.

[0067] exist Figure 1 and Figure 2 In the figure, reference numeral "C3" is the output capacitor used to form the DC voltage output to the auxiliary battery 30.

[0068] The specific operation and function of the power conversion system for a vehicle having the above configuration, according to the present disclosure, can be more clearly understood from the following description of the control method for the power conversion system for a vehicle.

[0069] Figure 3 This is a flowchart illustrating a control method for a power conversion system according to another form of this disclosure.

[0070] refer to Figure 3 The control method for the vehicle's power conversion system can begin from step S11, where the controller 700 determines the vehicle's operating mode.

[0071] In step S11, the controller 700 can determine whether the vehicle is in a driving mode propelled by the actuation of the motor 500 or in a charging mode in which the battery 20 is charged using charging power provided by the external charging device 10, by referring to input signals regarding the vehicle driving mode provided by the advanced controller, the connection of the external charging device 10, and various input signals in response to the driver's operation.

[0072] In step S11, when it is determined that the vehicle is in charging mode, the controller 700 can perform a control operation to convert the AC charging power provided by the external charging device 10 into DC power and provide DC power to the battery 20.

[0073] In step S21, the controller 700 short-circuits the switching device R1 and controls the states of switching elements Q1 to Q4 in the first bridge circuit 110 to apply AC voltage to the first coil 210 of the transformer 200. Accordingly, AC voltage is induced in the second coil 220 via the electromagnetic coupling between the first coil 210 and the second coil 220, according to the turns ratio between the first coil 210 and the second coil 220. The controller 700 can rectify the output AC voltage induced by the second coil 220 by controlling switching elements Q5 to Q8 in the second bridge circuit 120. The capacitor C1 connected to the output terminal of the second bridge circuit 120 smooths the voltage output from the second bridge circuit 120, thereby forming a DC voltage.

[0074] Furthermore, in step S21, the controller 700 can control the switching elements Q9 to Q14 in the converter 600 to boost the voltage applied to the neutral point of the motor 500 via the switching element R1 and output the boosted voltage to the battery 20. Here, since its cathode is connected to the output terminal of the second bridge circuit 120, Figure 1 The diode D1 shown can prevent the output voltage of the AC-DC conversion circuit 100 from being directly applied to the battery 20. Furthermore, in an embodiment where an active switch R2 is provided between the AC-DC conversion circuit 100 and the battery 20, the controller 700 can prevent the output voltage of the AC-DC conversion circuit 100 from being directly applied to the battery 20 by opening the active switch R2.

[0075] In the charging mode, in step S22, because the voltage of the auxiliary battery 30 is lower than a predetermined reference value or the charging state of the auxiliary battery 30 is lower than a predetermined reference value, when the controller 700 determines that charging is required, in step S23, the controller 700 can operate the low-voltage converter 400 to apply voltage to the auxiliary battery 30.

[0076] In step S23, the electromagnetic induction between the first coil 210 and the third coil 230 of the transformer 200 allows an AC voltage to be applied to the third coil 230 at the turns ratio between the first coil 210 and the third coil 230. Furthermore, the AC voltage applied to the capacitor C2 and smoothed by the capacitor C2, and induced in the third coil 230, is rectified through the connection structure of the two diodes D2 and D3. Here, the controller 700 can control the smoothing switching element Q15 to be short-circuited. Additionally, the controller 700 can control the duty cycle of the buck switching element Q16 to generate a voltage (on an order of magnitude suitable for charging the auxiliary battery 30) at the output terminal of the low-voltage converter 400.

[0077] In step S11, when it is determined that the vehicle is in driving mode, the controller 700 opens the switching device R1 and opens all switching elements Q1 to Q4 in the first bridge circuit 110. Afterwards, the controller 700 cannot perform any additional control operations. That is, in driving mode, in step S31, the controller 700 cannot operate the first bridge circuit 110.

[0078] In step S31, the controller 700 can apply the voltage of the battery 20 to the auxiliary battery 30 by converting the order of magnitude of the voltage of the battery 20. Figure 1 In the illustrated embodiment, the voltage of the battery 20 can be supplied to the second bridge circuit 120 via diode D1. Figure 2 In the illustrated embodiment, the controller 700 can short-circuit the active switch R2 to apply the voltage of the battery 20 to the second bridge circuit 120.

[0079] Furthermore, in step S31, the controller 700 can apply an AC voltage to the second coil 220 by controlling the open or short circuit of switching elements Q5 to Q8 in the second bridge circuit 120. Correspondingly, the electromagnetic induction between the second coil 220 and the third coil 230 of the transformer 200 can induce an AC voltage in the third coil 230 at the turns ratio between the second coil 220 and the third coil 230. The AC voltage induced in the third coil 230, smoothed by the capacitor C2 and applied to the capacitor C2, can be rectified through the connection structure of the two diodes D2 and D3. Here, the controller 700 can control the smoothing switching element Q15 to be short-circuited. Furthermore, the controller 700 can generate a voltage (of an order of magnitude suitable for charging the auxiliary battery 30) at the output terminal of the low-voltage converter 400 by controlling the duty cycle of the buck switching element Q16.

[0080] As described above, according to various forms of this disclosure, in the vehicle's charging mode, the battery 20 can be charged by directing power flow in the order of the first bridging circuit 110, the second bridging circuit 120, the motor 500, and the converter 600. To charge the auxiliary battery 30, power flow can be directed from the first bridging circuit 110 to the low-voltage converter 400 as needed. Furthermore, in the vehicle's driving mode, the first bridging circuit 110 can be deactivated, and power flow can be directed in the order of the battery 20, the second bridging circuit 120, and the low-voltage converter 400 to charge the auxiliary battery 30 or apply electrical voltage to the vehicle's electrical components.

[0081] As described above, unlike vehicle power conversion systems in related technical fields, the various forms of vehicle power conversion systems and control methods according to this disclosure can eliminate multiple components, such as power factor correction circuits or isolation converters, that are typically located in the on-board charger. The second bridge circuit of the AC-DC converter can be shared with the first side of the low-voltage converter, reducing the number of components and the size and weight of the system. Consequently, due to reduced manufacturing costs and fewer components, the power conversion system in the vehicle can be easily packaged and mass-produced.

[0082] Although the specific form of this disclosure has been described for illustrative purposes, those skilled in the art will recognize that various modifications, additions, and substitutions are possible without departing from the scope and substance of this disclosure.

Claims

1. A power conversion system for a vehicle, the power conversion system comprising: An AC-DC conversion circuit is configured to convert AC charging power into DC power. An electric motor includes multiple coils, each having a first end connected to a neutral point; The first switching device is configured to selectively allow or prevent the supply of output power from the AC-DC conversion circuit to the neutral point; The converter includes: Multiple motor connection terminals are respectively connected to the second ends of the multiple coils of the motor; DC connection terminals, including positive and negative terminals; and Multiple switching elements form an electrical connection between the DC connection terminal and the multiple motor connection terminals; The battery is connected to the DC connection terminal of the converter; and The controller is configured to control the operation of the AC-DC conversion circuit, the first switching device, and the converter based on whether the battery is being charged. The AC-DC conversion circuit includes: The first bridging circuit includes a plurality of switching elements forming the bridging circuit and is configured to receive AC charging power from an external AC charging device; Transformers, including: The first coil is subjected to an AC voltage generated by a short circuit or open circuit of a switching element in the first bridge circuit; and A second coil, electromagnetically coupled to the first coil, transforms the AC voltage applied to the first coil at a predetermined ratio; and The second bridge circuit includes multiple switching elements, and the second bridge circuit is configured as follows: The output voltage of the second coil is rectified or the input DC voltage is converted into AC voltage; and The converted AC voltage is applied to the second coil. The first bridging circuit includes: The first input terminal and the second input terminal are used to apply the voltage of the AC charging power between the first input terminal and the second input terminal; The first switching element and the second switching element each have a first terminal that is respectively connected to the first input terminal; A third switching element is connected to the second terminal of the first switching element; and A fourth switching element is connected between the second terminal of the second switching element and the first terminal of the third switching element; The two ends of the first coil of the transformer are respectively connected to the connection nodes of the second input terminal and the third and fourth switching elements.

2. The power conversion system according to claim 1, wherein, The second bridging circuit includes: a fifth switching element; a sixth switching element having a first terminal connected to a first terminal of the fifth switching element; a seventh switching element having a first terminal connected to a second terminal of the fifth switching element; and an eighth switching element connected between the second terminal of the sixth switching element and the second terminal of the seventh switching element. The second coil of the transformer is connected to the connection node of the fifth and sixth switching elements and the connection node of the seventh and eighth switching elements; and The voltage applied between the connection nodes of the fifth and seventh switching elements and the connection nodes of the sixth and eighth switching elements is the output voltage of the AC-DC conversion circuit.

3. The power conversion system according to claim 2, further comprising: A DC capacitor has two ends connected to the connection nodes of the fifth and seventh switching elements and the connection nodes of the sixth and eighth switching elements, respectively.

4. The power conversion system according to claim 1, further comprising: A DC capacitor is connected to the output terminal of the second bridge circuit.

5. The power conversion system according to claim 1, wherein, In a charging mode where the battery is charged using the AC charging power... The controller is configured to: The output voltage of the AC-DC conversion circuit applied to the neutral point is controlled by short-circuiting the first switching device; and The plurality of switching elements are controlled such that the circuit comprising the plurality of coils and the plurality of switching elements in the converter operates as a boost converter.

6. The power conversion system according to claim 5, wherein, The controller is configured to: Control the duty cycle of the switching element connected to the negative terminal among the plurality of switching elements in the converter; The charging voltage applied to the DC connection terminal is boosted so that the boosted voltage is applied to the battery.

7. The power conversion system according to claim 1, wherein, The transformer further includes: A third coil, electromagnetically connected to either the first or second coil, outputs the voltage of the first or second coil by transforming the voltage at a predetermined ratio; and A low-voltage converter, controlled by the controller, converts the voltage output from the third coil into a predetermined voltage that is lower than the voltage of the battery.

8. The power conversion system according to claim 7, wherein, The low-voltage converter includes: A rectifier is configured to rectify the voltage output from the third coil; A smoother is configured to smooth the voltage rectified by the rectifier; and A voltage converter is configured to convert a smooth voltage into the predetermined voltage.

9. The power conversion system according to claim 8, wherein, The rectifier includes a first diode having a cathode connected to a first end of the third coil and a second diode having a cathode connected to a second end of the third coil; The smoother includes: A capacitor having a first end connected to the midpoint of the third coil; and The smooth switching element has: The first terminal is connected to the second terminal of the capacitor; and The second end is connected to the anodes of both the first diode and the second diode; and The voltage converter includes: A buck converter, comprising a buck switching element having a first terminal connected to the second terminal of the capacitor of the smoother; A third diode has a cathode connected to the second terminal of the buck switching element and an anode connected to the second terminal of the smooth switching element; and An inductor having one end connected to the cathode of the third diode.

10. The power conversion system according to claim 7, further comprising: The second switching device is connected between the positive terminal of the converter and the output terminal of the AC-DC conversion circuit.

11. The power conversion system according to claim 10, wherein, The second switching device includes: an active switch, the controller determining whether the active switch is short-circuited or open-circuited; or a diode having an anode connected to the positive terminal of the converter and a cathode connected to the output terminal of the AC-DC conversion circuit.

12. The power conversion system according to claim 10, wherein, In the charging mode in which the battery is charged using the AC charging power, the controller is configured as follows: Open the circuit of the second switching device; By short-circuiting the first switching device, the output voltage of the AC-DC conversion circuit is applied to the neutral point; Control the plurality of switching elements in the converter so that it operates as a boost converter through a circuit formed by the plurality of switching elements and the plurality of coils; and The low-voltage converter is controlled to convert the voltage output from the third coil through the electrical coupling between the first coil and the third coil into a predetermined voltage that is lower than the voltage of the battery.

13. The power conversion system according to claim 10, wherein, In the travel mode in which the motor is actuated, the controller is configured to: Open the circuit of the first switching device; The voltage of the battery is applied to the second bridge circuit by short-circuiting the second switching device; The voltage of the battery is switched by controlling the state of the switching element in the second bridge circuit so that AC voltage is applied to the second coil; Control the plurality of switching elements in the converter such that the circuit formed by the plurality of switching elements and the plurality of coils operates as a boost converter; and The low-voltage converter is controlled to convert the voltage transformed and output from the third coil through the electrical coupling between the second coil and the third coil into a predetermined voltage that is lower than the voltage of the battery.

14. The power conversion system according to claim 13, wherein, The controller is configured to open the switching element in the first bridge circuit during the travel mode in which the motor is actuated.

15. A control method for a power conversion system for a vehicle according to any one of claims 1 to 14, the method comprising: The controller determines whether the vehicle is in a charging mode where the battery is charged using AC charging power or in a driving mode where the motor is actuated. When the vehicle is in the charging mode, the first switching device is short-circuited and the second switching device is open-circuited, thereby applying the output voltage of the AC-DC circuit to the neutral point and controlling multiple switching elements in the converter so that the circuit formed by the multiple coils and the multiple switching elements in the converter operates as a boost converter. Control a low-voltage converter to convert the voltage output from the third coil through electrical coupling between the first and third coils into a predetermined voltage lower than the voltage of the battery; and When the vehicle is in the driving mode, the first switching device is opened, and the second switching device is short-circuited to apply the battery voltage to the second bridge circuit. The battery voltage is converted by controlling the state of the switching elements in the second bridge circuit to apply AC voltage to the second coil. The plurality of switching elements in the converter are controlled so that the circuit formed by the plurality of switching elements and the plurality of coils operates as a boost converter, and the low-voltage converter is controlled to convert the voltage converted and output from the third coil through the electrical coupling between the second coil and the third coil into a predetermined voltage lower than the battery voltage.

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