Battery heating system and method using motor drive system

Abstract

The present invention discloses a battery heating system utilizing a motor drive system, comprising: an inverter having a plurality of legs, the plurality of legs respectively comprising a pair of switching elements connected in series between two ends of a battery and respectively corresponding to a plurality of phases; a motor having a plurality of coils, one end of each of the plurality of coils respectively connected to a connection end between a pair of switching elements included in the plurality of legs, and the other end of each of the plurality of coils connected to each other; and a controller determining one of the plurality of phases as a reference phase, and alternately controlling the on / off state of the switching element so that the on / off states of the switching element included in the leg corresponding to the reference phase and the switching elements included in the remaining legs become complementary to each other, so as to generate an alternating current injected into the battery.

Description

Technical Field

[0001] The present invention relates to a battery heating system and method using a motor drive system, and more specifically, to a battery heating system and method using a motor drive system including an inverter and a motor arranged in a vehicle to inject alternating current into a battery so that the battery can be repeatedly charged and discharged to increase the temperature of the battery. Background Art

[0002] Generally, an environmentally friendly vehicle driven by electric energy includes a battery for storing electric energy, an inverter for converting the electric energy stored in the battery into AC power having multiple phases, and a motor for generating rotational kinetic energy using the AC power converted in the inverter.

[0003] Recently, batteries for environmentally friendly vehicles are mainly made of lithium-ion batteries. Lithium-ion batteries have excellent energy density at room temperature and excellent performance when considering charge and discharge cycles. However, due to the characteristics of the electrolyte that constitutes the lithium-ion battery, it has the disadvantages of reduced capacity, increased resistance, and reduced efficiency at low temperatures. In particular, when the lithium-ion battery is charged at low temperatures or overcharged, lithium ions are unevenly deposited on the surface of the cathode, thereby shortening its life. Therefore, lithium-ion batteries require a heating device that can quickly raise the temperature from a low temperature state to a high-efficiency high temperature state.

[0004] Traditionally, a method of adding a heater (e.g., a positive temperature coefficient (PTC) heater) to the battery is used to directly heat the battery or to heat and circulate cooling water supplied to the battery. However, this existing battery heating method requires the addition of an additional heater, which results in additional cost and volume increase.

[0005] As another existing battery heating technology, a method of electrically generating heat inside the battery has been studied. This method is a method that utilizes the internal resistance of the battery, and is a method of causing current to flow through the battery and using the loss generated in proportion to the amount of current flowing as heat. This method allows the current to flow through the battery evenly, so it has the advantage of evenly increasing the battery heat. However, since an additional dedicated circuit is required to flow current into the battery, it also leads to additional volume and cost, and an additional management point is generated for the dedicated circuit that generates and circulates current for battery heating, so the maintenance and management of the vehicle becomes complicated.

[0006] The above background technology is only used to enhance the understanding of the background of the present invention and should not be regarded as an admission that it corresponds to the prior art known to ordinary technicians in the field.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: KR 10-2011-0112132A

[0010] Patent Document 2: JP 2016-004649A Summary of the invention

[0011] 1. Technical issues to be resolved

[0012] The technical problem to be solved by the present invention is to provide a battery heating system and method using a motor drive system, which uses a motor drive system including an inverter and a motor arranged in a vehicle to inject alternating current into a battery so that the battery can be repeatedly charged and discharged to increase the temperature of the battery without an additional heating device for increasing the battery temperature.

[0013] (II) Technical solution

[0014] As a method for solving the above-mentioned technical problems, the present invention provides a battery heating system utilizing a motor drive system, comprising: an inverter having a plurality of legs, the plurality of legs respectively including a pair of switching elements connected in series between the two ends of a battery and respectively corresponding to a plurality of phases; a motor having a plurality of coils, one end of each of the plurality of coils respectively connected to a connection end between a pair of switching elements included in the plurality of legs, and the other end of each of the plurality of coils connected to each other; and a controller determining one of the plurality of phases as a reference phase, and alternately controlling the on / off state of the switching element so that the on / off states of the switching element included in the leg corresponding to the reference phase and the switching elements included in the remaining legs become complementary to each other to generate an alternating current injected into the battery.

[0015] In one embodiment of the present invention, the controller can control the on / off states of a pair of switching elements included in the multiple legs to be complementary to each other, and control the on / off states of the switching elements connected to the positive terminal of the battery among the switching elements in the leg corresponding to the reference phase and the switching elements connected to the positive terminal of the battery among the switching elements in the remaining legs to be complementary to each other.

[0016] In one embodiment of the present invention, the controller may determine the reference phase based on the rotor angle.

[0017] In one embodiment of the present invention, the controller may select the reference phase so as to minimize the difference between an angle represented by a motor current generated by alternately controlling the on / off state of the switching element in a dq stationary coordinate plane and the rotor angle.

[0018] As another method for solving the above technical problems, the present invention provides a battery warming system using a motor drive system, comprising: an inverter having an a-phase leg, a b-phase leg and a c-phase leg, each including a pair of switching elements connected in series between two ends of a battery; a motor including an a-phase coil, a b-phase coil and a c-phase coil, one end of the a-phase coil being connected to a connection node between a pair of switching elements included in the a-phase leg, one end of the b-phase coil being connected to a connection node between a pair of switching elements included in the b-phase leg, one end of the c-phase coil being connected to a connection node between a pair of switching elements included in the c-phase leg, and the other end of the a-phase coil, the other end of the b-phase coil and the other end of the c-phase coil being connected to each other; and a controller determining one of the a-phase, b-phase and c-phase as a reference phase, and alternately performing on / off control so that the on / off state of the switching element included in the leg corresponding to the reference phase and the on / off state of the switching element included in the leg corresponding to the remaining phases become complementary to each other to generate an alternating current injected into the battery.

[0019] In one embodiment of the present invention, the controller can control the on / off states of a pair of switching elements included in the multiple legs to be complementary to each other, and can control the states of the switching element connected to the positive terminal of the battery among the switching elements of the leg corresponding to the reference phase and the switching elements connected to the positive terminal of the battery among the switching elements of the remaining legs to be complementary to each other.

[0020] In one embodiment of the present invention, the controller may determine the reference phase based on the rotor angle.

[0021] In one embodiment of the present invention, the controller can determine, as the reference phase, the phase of the leg having the smallest difference between the generated motor current and the rotor angle among the angles represented in the dq stationary coordinate plane by the motor current generated when the a-phase leg is determined as the reference phase and the switching element is controlled, the motor current generated when the b-phase leg is determined as the reference phase and the switching element is controlled, and the motor current generated when the c-phase leg is determined as the reference phase and the switching element is controlled.

[0022] In one embodiment of the present invention, the controller may determine phase a as the reference phase when the rotor angle is 0° to 30°, 150° to 210°, and 330° to 360°, and alternately control the switching element to be turned on / off to generate the AC current.

[0023] In one embodiment of the present invention, the controller may determine the c phase as the reference phase when the rotor angle is 30° to 90° and 210° to 270°, and the switching element may be alternately on / off controlled to generate the AC current.

[0024] In one embodiment of the present invention, the controller may determine the b-phase as the reference phase when the rotor angle is 90° to 150° and 270° to 330°, and alternately perform on / off control on the switching element to generate the AC current.

[0025] As another method for solving the above-mentioned technical problem, the present invention provides a battery heating method using a motor drive system, which, as a battery heating method using the above-mentioned battery heating system, includes the following steps: judging the interval to which the rotor angle belongs; determining the reference phase based on the interval to which the rotor angle belongs; and alternately performing on / off control so that the on / off state of the switching element included in the leg corresponding to the reference phase and the on / off state of the switching element included in the leg corresponding to the remaining phases become complementary to each other to generate an alternating current injected into the battery.

[0026] In one embodiment of the present invention, in the judging step, when the rotor angle is 0° to 30°, 150° to 210°, and 330° to 360°, the determining step may determine the a phase as the reference phase, and the generating step alternately controls the on / off states of the switching elements included in the a phase leg and the b phase leg and the c phase leg to generate the alternating current.

[0027] In one embodiment of the present invention, the generating step can control the states of a pair of switching elements respectively included in the a-phase leg, the b-phase leg and the c-phase leg to be complementary to each other, and control the states of the switching element connected to the positive terminal of the battery among the switching elements included in the a-phase leg and the switching elements connected to the positive terminal of the battery among the switching elements included in the b-phase leg and the c-phase leg to be complementary to each other.

[0028] In one embodiment of the present invention, in the judging step, when the rotor angle is 30° to 90° and 210° to 270°, the determining step may determine the C phase as the reference phase, and the generating step alternately controls the on / off states of the switching elements included in the C phase leg and the switching elements included in the A phase leg and the B phase leg to generate the AC current.

[0029] In one embodiment of the present invention, the generating step can control the states of a pair of switching elements respectively included in the a-phase leg, the b-phase leg and the c-phase leg to be complementary to each other, and control the states of the switching element connected to the positive terminal of the battery among the switching elements included in the c-phase leg and the switching elements connected to the positive terminal of the battery among the switching elements included in the a-phase leg and the b-phase leg to be complementary to each other.

[0030] In one embodiment of the present invention, in the judgment step, when the rotor angle is 90° to 150° and 270° to 330°, the determination step can determine the b phase as the reference phase, and the generation step alternately controls the on / off states of the switching elements included in the b phase leg and the a phase leg and the c phase leg to generate the alternating current.

[0031] In one embodiment of the present invention, the generating step can control the states of a pair of switching elements respectively included in the a-phase leg, the b-phase leg and the c-phase leg to be complementary to each other, and control the states of the switching element connected to the positive terminal of the battery among the switching elements included in the b-phase leg and the switching elements connected to the positive terminal of the battery among the switching elements included in the a-phase leg and the c-phase leg to be complementary to each other.

[0032] (III) Beneficial effects

[0033] According to the battery heating system and method using the motor drive system, without adding additional heating devices such as heaters, the inverter and motor required to drive an environmentally friendly vehicle are used to inject AC current into the battery, thereby effectively heating the battery without adding additional costs.

[0034] In particular, according to the battery heating system and method using the motor drive system, when the inverter and the motor generate AC current, the torque pulsation generated by the motor can be suppressed to the maximum extent, thereby improving the stability of the vehicle.

[0035] The effects that can be obtained by the present invention are not limited to the above-mentioned effects, and a person skilled in the art can clearly understand other effects of the present invention that are not mentioned through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a circuit diagram of a battery warming system using a motor drive system according to an embodiment of the present invention.

[0037] Figure 2 1 is a waveform diagram for explaining a technique for generating a battery current in a motor drive system and method according to an embodiment of the present invention.

[0038] Figure 3 1 is a vector diagram for explaining a technique for minimizing torque ripple in a motor drive system and method according to an embodiment of the present invention.

[0039] Figure 4 is a flow chart of a battery temperature increasing method using a motor drive system according to one embodiment of the present invention.

[0040] Description of Reference Numerals

[0041] 10: Battery 20: Inverter

[0042] 21, 23, 25: Legs 30: Motor

[0043] L1: a-phase coil L2: b-phase coil

[0044] L3: c-phase coil 40: rotor position sensor

[0045] 100: Controller DETAILED DESCRIPTION

[0046] Hereinafter, a battery heating system using a motor driving system according to various embodiments will be described in detail with reference to the accompanying drawings.

[0047] Figure 1 is a circuit diagram of a battery warming system using a motor drive system according to an embodiment of the present invention.

[0048] like Figure 1As shown, a conventional system for driving the motor 30 includes: a battery 10 as an energy storage device for storing power for driving the motor 30; and an inverter 20, which converts the DC power stored in the battery 10 into an AC having multiple phases and supplies it to the motor 30. The inverter 20 has three legs 21, 23, 25 connected in parallel to each other at both ends of the battery 10, each leg 21, 23, 25 has two switching elements (two of S1 to S6) connected in series to each other, and supplies a single-phase driving power to the motor 30 from the connection node of the two switching elements. In order to drive such a motor, pulse width modulation control of the switching elements S1 to S6 in the inverter 20 can be performed to supply the motor 30 with a current corresponding to a current command corresponding to the torque of the motor 30 desired to be obtained by driving the motor 30.

[0049] According to a battery warming system using a motor drive system in one embodiment of the present invention, this conventional motor drive system is used to suppress the torque generated in the motor 30, and at the same time, the states of the switching elements S1 to S6 in the inverter 20 are controlled to inject AC current (pulsating current) into the battery 10.

[0050] Specifically, a battery heating system utilizing a motor drive system according to an embodiment of the present invention may be configured to include: a battery 10; an inverter 20 having a plurality of legs 21, 23, 25, the plurality of legs 21, 23, 25 respectively including a pair of switching elements S1 to S6 connected in series to each other at both ends of the battery 10; a motor 30 having a plurality of coils L1, L2, L3, the plurality of coils L1, L2, L3 being respectively connected to connection ends of the switching elements included in the legs 21, 23, 25 in the inverter 20; and a controller 100, controlling the switching element included in one of the plurality of legs in the inverter 20 and the switching elements included in the remaining two legs into a complementary relationship to each other so as to generate an alternating current injected into the battery 10.

[0051] For example, in one embodiment of the present invention, the controller 100 complementarily controls a pair of switching elements included in each leg 21, 23, 25 within the inverter 20, and complementarily controls the switching element S1 connected to the positive (+) terminal of the battery 10 among the switching elements S1, S2 included in the first leg 21 of the multiple legs 21, 23, 25 and the switching elements S3, S5 connected to the positive (+) terminal of the battery 10 among the switching elements included in the remaining two legs 23, 25 to change the polarity of the voltage applied to the coils L1 to L3 corresponding to multiple phases included in the motor 30, so that alternating current can be applied to the battery 10.

[0052] When the temperature of the battery 10 is increased by utilizing the heat generated in the internal resistance of the battery 10 , it is necessary to focus on the amount of heat generation and efficiency.

[0053] First, the amount of heat generated is proportional to the amount of current flowing through the battery 10. That is, regardless of the direction, a large amount of heat is generated when a large amount of current flows through the internal resistance of the battery 10. In view of this, by charging by supplying a direct current to the battery 10 or discharging by outputting a direct current from the battery 10, the amount of charge or discharge can be increased to increase the amount of heat generated by the battery 10.

[0054] Secondly, in order to improve efficiency, it is more preferable to perform charging and discharging of the battery 10 alternately rather than performing only one of charging or discharging of the battery 10. When charging and discharging of the battery 10 are performed alternately as described above, although less energy is consumed in the battery 10, the amount of current flowing through the battery 10 can be increased, so that the amount of heat generated can be greatly increased while improving energy efficiency. That is, when an alternating current is injected into the battery 10 instead of a direct current, the current is repeatedly output from the battery 10 and input to the battery 10, so that the heat generation of the battery 10 can be induced with high energy efficiency.

[0055] At this time, if the frequency of the alternating current is high enough, the battery 10 can generate heat while preventing lithium precipitation inside the battery 10 and the resulting battery aging.

[0056] In view of this, in various embodiments of the present invention, the switching elements S1 to S6 within the inverter 20 may be controlled so that an alternating current having a high frequency is injected into the battery.

[0057] In order to inject the AC current into the battery 10, it is necessary to receive and store energy from the battery 10 and to supply the stored energy to the battery 10 again. To achieve the energy storage required here, in various embodiments of the present invention, the coils L1 to L3 corresponding to the plurality of phases provided in the motor 30 may be utilized. That is, the storage and release of energy may be achieved on the coils L1 to L3 of the motor 30, so that the AC current is injected into the battery 10.

[0058] Furthermore, in order to inject high-frequency AC current into the battery 10 by the inverter 20 and the motor 30 to increase the temperature of the battery 10 , in addition to ensuring the battery current as described above, the motor 30 must also suppress the torque generated.

[0059] Figure 2 1 is a waveform diagram for explaining a technique for generating a battery current in a motor drive system and method according to an embodiment of the present invention. Figure 3 1 is a vector diagram for explaining a technique for minimizing torque ripple in a motor drive system and method according to an embodiment of the present invention.

[0060] Reference Figure 2 and Figure 3, the technology of generating the alternating current injected into the battery 10 and the technology of suppressing the torque generated by the motor 30 in the process of generating the alternating current injected into the battery 10 are described in more detail.

[0061] First, refer to Figure 2 According to an embodiment of the present invention, in a battery heating system utilizing a motor drive system, the controller 100 may control the on / off state of the switching element so that the on / off relationship between the switching element included in one of the three legs included in the inverter 20 and the switching elements included in the remaining legs become complementary to each other. Figure 2 In the example shown, in which the connection ends of the switching elements S1 and S2 in the first leg 21 are connected to the a-phase coil L1 of the motor 30, the connection ends of the switching elements S3 and S4 in the second leg 23 are connected to the b-phase coil L2 of the motor 30, and the connection ends of the switching elements S5 and S6 in the third leg 25 are connected to the c-phase coil L3 of the motor 30, the switching elements in the first leg 21 and the switching elements in the second and third legs 23 and 25 are controlled to be complementary to each other.

[0062] exist Figure 2 In the "D1" interval shown, the controller 100 controls the switching elements S1 to S6, so that the a-phase voltage Van provided to the a-phase coil L1 of the motor 30 becomes a high state, and the b-phase voltage Vbn and the c-phase voltage Vcn applied to the b-phase coil L2 and the c-phase coil L3 become a low state. That is, the controller 100 turns on the switching element S1 of the first leg 21 and turns off the switching element S2, turns off the switching element S3 of the second leg 23 and turns on the switching element S4, turns off the switching element S5 of the third leg 25 and turns on the switching element S6.

[0063] Through such control, in interval D1, the a-phase coil L1 of the motor 30 is connected to the positive (+) terminal side of the battery 10, so the current Ias flowing through the a-phase coil L1 of the motor 30 increases, while the currents Ibs and Ics flowing through the b-phase coil L2 and the c-phase coil L3 decrease. Here, the direction in which the currents Ias, Ibs, and Ics of each phase flow from the inverter 20 to the motor 30 is called positive (+), and the opposite direction is called negative (-). Due to the electrical characteristics of the coil (inductor) that stores energy, even if an electrical path is formed by the switching of the switching element, the currents Ias, Ibs, and Ics flowing through each coil will gradually increase or decrease. Therefore, the direction of the current is changed after maintaining the direction of the current flowing in the previous interval for a period of time. Here, one end of the coils L1, L2, L3 corresponding to each phase of the motor 30 is connected to a node where a pair of switching elements included in each leg 21, 23, 25 of the inverter 20 are connected to each other, and the other end can be commonly connected between the coils L1, L2, L3 to form a neutral point.

[0064] When the preset switching frequency is changed from the "D1" interval to the "D2" interval, the controller 100 controls the switching elements S1, S2, S5, and S6 so that the b-phase voltage Vbn and the c-phase voltage Vcn respectively applied to the b-phase coil L2 and the c-phase coil L3 of the motor 30 become high states, and the a-phase voltage Van provided to the a-phase coil L1 becomes low states. That is, the controller 100 turns off the switching element S1 of the first leg 21 and turns on the switching element S2, turns on the switching element S3 of the second leg 23 and turns off the switching element S4, turns on the switching element S5 of the third leg 25 and turns off the switching element S6.

[0065] Here, the switching frequency may be changed according to the operating state of the vehicle to which the system of the present invention is applied or the temperature of the battery. The controller 100 may pre-store a factor as a reference for determining the switching frequency and pre-stored mapping data of the switching frequency corresponding to the factor or a predetermined formula that can calculate the switching frequency from the factor, and when performing control for battery temperature increase, the stored mapping data or formula may be used to find the switching frequency. Of course, in addition to the switching frequency, the switching duty cycle may also be determined by pre-stored mapping data or formulas. Figure 2 Although an example in which the switching duty ratio is approximately 50% is shown, it can be changed appropriately.

[0066] The specific method of determining the switching frequency and the switching duty cycle has no direct relevance to the main technical concept of the present invention, so further detailed description thereof is omitted.

[0067] Through such control, in interval D2, the b-phase coil L2 and the c-phase coil L3 of the motor 30 are connected to the positive (+) terminal side of the battery 10, so the currents Ibs and Ics flowing through the b-phase coil L2 and the c-phase coil L3 of the motor 30 increase, while the current Ias flowing through the a-phase coil L1 decreases. As described above, due to the characteristics of the inductor, even if the on / off state of the switching element is changed in interval D2, the direction of the current flowing in the previous interval D1 will be maintained for a period of time and its magnitude will gradually decrease, and the direction of the current will change after a period of time. At this time, even if the same voltage is applied to the b-phase coil L2 and the c-phase coil L3 of the motor 30, a difference in current will occur due to the difference in impedance between each other, which may cause current pulsation that is not aligned with the a-phase. Here, since the average value of the current of each phase converges to zero, no average torque is generated.

[0068] That is, when the switching interval changes, even if the connection state of the switching element changes, the flow of the current in the previous interval is maintained for a period of time, so that the battery 10 can be in a charging state as a state of receiving current input, and after a period of time, in a discharging state where current is output from the battery 10 until the next switching interval changes. Figure 2 Ibat is shown in FIG. Figure 2 As shown, the battery current Ibat is an AC current that pulsates at 1 / 2 of the switching cycle D1+D2, that is, at twice the switching frequency. In summary, according to a battery heating system using a motor drive system in one embodiment of the present invention, the switching elements in the inverter 20 are controlled so that the voltage applied to the coil corresponding to one phase of the motor 30 and the voltage applied to the coil corresponding to the remaining phases become complementary to each other according to a preset switching frequency, thereby generating an AC current injected into the battery 10.

[0069] In addition, in one embodiment of the present invention, the motor 30 should be prevented from generating torque to the greatest extent possible during the control process of the switching elements S1 to S6 for heating the battery 10. As described above, the method of generating current by determining the phase voltages of the coil corresponding to one phase and the coil corresponding to the remaining two phases of the motor in a manner that complements each other can be as follows. Figure 3 The arrows indicated by the reference numerals “ 51 , 52 , 53 ” also generate electric currents.

[0070] When the a-phase voltage and the remaining b-phase and c-phase voltages are controlled complementarily to each other, a motor current 51 formed between the vertices of the hexagon corresponding to the

[100] and

[011] vectors can be formed, when the b-phase voltage and the remaining a-phase and c-phase voltages are controlled complementarily to each other, a motor current 52 formed between the vertices of the hexagon corresponding to the

[010] and

[101] vectors can be formed, and when the c-phase voltage and the remaining a-phase and b-phase voltages are controlled complementarily to each other, a motor current 53 formed between the vertices of the hexagon corresponding to the

[110] and

[001] vectors can be formed. Here, the arrows indicated by the reference numeral "51" correspond to 0° and 180° with respect to the a-axis, the arrows indicated by the reference numeral "52" correspond to 120° and 300° with respect to the a-axis, and the arrows indicated by the reference numeral "53" correspond to 60° and 240° with respect to the a-axis.

[0071] In addition, the torque generated in the motor according to the motor current can be expressed as the following formula 1 in the case of a permanent magnet synchronous motor having salient polarity.

[0072] Formula 1

[0073]

[0074] In the above formula 1, T e is the motor torque, λ f is the electromotive force of the motor, L d , L q is the d-axis and q-axis inductance of the motor, i d 、i q are the d-axis and q-axis currents of the motor.

[0075] As shown in the above formula 1, it can be seen that the torque generated in the motor is when the q-axis current is 0 (i q =0). That is, when the motor current does not flow to the q-axis of the synchronous coordinate system but only exists in the d-axis, the motor does not generate torque.

[0076] Therefore, when the d-axis, which is an axis connecting the n-pole and the s-pole of the rotor of the motor 30, is as shown in FIG. Figure 3 When the angle of the rotor is consistent with the arrow, Figure 3 When the angles corresponding to the arrows are 0°, 60°, 120°, 180°, 240°, and 300°, the torque of the motor 30 may be 0.

[0077] The rotor position of the motor 30 is randomly determined, so in one embodiment of the present invention, the rotor angle detected by the rotor position sensor 40 provided on the motor 30 and the angle corresponding to the motor current generated by the switching control of the switching element of the inverter 20 are selected. Figure 3 The phase with the smallest difference between the angles (the angles formed by the arrows 51, 52, and 53 with respect to the a-axis) is switched on / off by controlling the switching element so that the voltages of the selected phase and the remaining two phases become complementary to each other, thereby minimizing the generation of torque.

[0078] Of course, a sensorless method known in the art may be used to detect the position of the rotor instead of the rotor position sensor 40. The sensorless algorithm for detecting the rotor position is known in the art in various ways, so additional description is omitted.

[0079] Reference Figure 3 When the rotor angle is 0° to 30°, 150° to 210°, and 330° to 360°, it is preferred to perform control based on the a phase corresponding to the arrow 51. That is, it is preferred to alternately control the on / off state of the switching element at a preset switching frequency so that the a phase voltage and the remaining b phase and c phase voltages become complementary to each other.

[0080] In addition, when the rotor angle is 30° to 90° and 210° to 270°, it is preferable to perform control based on the c-phase corresponding to the arrow 53. That is, it is preferable to alternately control the on / off state of the switching element at a preset switching frequency so that the c-phase voltage and the remaining a-phase and b-phase voltages become complementary to each other.

[0081] In addition, when the rotor angle is 90° to 150° and 270° to 330°, it is preferable to perform control based on the b-phase corresponding to the arrow 52. That is, it is preferable to alternately control the on / off state of the switching element at a preset switching frequency so that the b-phase voltage and the remaining a-phase and c-phase voltages become complementary to each other.

[0082] The present invention also provides a battery heating method achieved by the battery heating system utilizing the motor drive system.

[0083] Figure 4 is a flow chart of a battery temperature increasing method using a motor drive system according to one embodiment of the present invention.

[0084] Reference Figure 4 According to an embodiment of the present invention, a battery temperature increasing method using a motor drive system may be configured to include: step S11, the controller 100 receives an input of a rotor angle of the motor 30 detected by the rotor position sensor 40, and determines the interval to which the rotor angle belongs; and steps S21, S22, and S23, the controller 100 determines a phase as a reference based on the interval to which the rotor angle belongs, and controls the switching element to be turned on / off at a preset switching frequency to inject an AC current into the battery 10. The above steps may be repeated until the temperature T of the battery reaches 0. bat The temperature rises to a preset target temperature (S24).

[0085] In step S11, the controller 100 determines the a-phase voltage as a reference when the rotor angle is in the intervals of 0° to 30°, 150° to 210°, and 330° to 360° (S21). That is, the controller 100 uses the on / off state of the switching element S1 of the first leg 21 of the inverter 20 as a reference, alternately controls the switching element at a preset switching frequency, and makes the on / off state of the switching element S3 of the second leg 23 and the switching element S5 of the third leg 25 complementary to the on / off state of the switching element S1, thereby generating an AC current (S21).

[0086] In step S11, the controller 100 determines the c-phase voltage as a reference when the rotor angle is in the range of 30° to 90° and 210° to 270° (S22). That is, the controller 100 uses the on / off state of the switching element S5 of the third leg 25 of the inverter 20 as a reference, and alternately controls the switching element at a preset switching frequency, so that the on / off state of the switching element S1 of the first leg 21 and the switching element S3 of the second leg 23 and the on / off state of the switching element S5 become complementary to each other, thereby generating an AC current (S22).

[0087] In step S11, the controller 100 determines the b-phase voltage as a reference when the rotor angle is in the range of 90° to 150° and 270° to 330° (S23). That is, the controller 100 uses the on / off state of the switching element S3 of the second leg 23 of the inverter 20 as a reference, and alternately controls the switching element at a preset switching frequency, so that the on / off state of the switching element S1 of the first leg 21 and the switching element S5 of the third leg 25 and the on / off state of the switching element S3 become complementary to each other, thereby generating an AC current (S23).

[0088] If, when the angle of the rotor is a value corresponding to the interval boundary, the reference phase may be any one of the phases corresponding to the two intervals having the boundary. For example, when the rotor angle is 90°, one of the c-phase and the b-phase may be determined as the reference phase. However, in order that the three phases may be uniformly determined as the reference phase, preferably, based on the frequency previously determined as the reference phase, the phase with a lesser frequency determined as the reference phase is determined as the reference phase.

[0089] As described above, according to the battery heating method using the motor drive system of various embodiments of the present invention, an inverter and a motor connected to the battery provided for driving an environmentally friendly vehicle are used to inject AC current into the battery without requiring an additional heating device, thereby achieving effective battery heating without adding additional costs. In particular, when the AC current is generated using the inverter and the motor, the torque pulsation generated in the motor can be suppressed to the maximum extent, thereby improving the stability of the vehicle.

[0090] The specific embodiments of the present invention have been shown and described above. However, it will be apparent to those skilled in the art that various modifications and changes may be made to the present invention within the scope of the claims.

Claims

1. A battery heating system using a motor drive system, comprising: An inverter having a plurality of legs, the plurality of legs respectively including a pair of switching elements connected in series with each other between both ends of a battery and respectively corresponding to a plurality of phases; a motor having a plurality of coils, one end of each of the plurality of coils being respectively connected to a connection end between a pair of switching elements included in the plurality of legs, and the other end of each of the plurality of coils being connected to each other; as well as a controller that determines one of the plurality of phases as a reference phase and alternately controls the on / off states of the switching elements so that the on / off states of the switching elements included in the leg corresponding to the reference phase and the switching elements included in the remaining legs become complementary to each other to generate an alternating current injected into the battery, It is characterized in that The controller determines the reference phase based on the rotor angle, and The controller selects the reference phase so that a difference between an angle represented in a dq stationary coordinate plane by a motor current generated by alternately controlling an on / off state of the switching element and the rotor angle is minimized.

2. The battery heating system using a motor drive system according to claim 1, characterized in that: The controller controls the on / off states of a pair of switch elements included in the plurality of legs to be in a complementary relationship with each other, and The on / off states of the switching elements connected to the positive terminal of the battery among the switching elements in the leg corresponding to the reference phase and the switching elements connected to the positive terminal of the battery among the switching elements in the remaining legs are controlled to complement each other.

3. A battery heating system using a motor drive system, comprising: an inverter having an a-phase leg, a b-phase leg, and a c-phase leg, each including a pair of switching elements connected in series with each other between both ends of a battery; A motor comprising an a-phase coil, a b-phase coil and a c-phase coil, wherein one end of the a-phase coil is connected to a connection node between a pair of switching elements included in the a-phase leg, one end of the b-phase coil is connected to a connection node between a pair of switching elements included in the b-phase leg, one end of the c-phase coil is connected to a connection node between a pair of switching elements included in the c-phase leg, and the other ends of the a-phase coil, the b-phase coil and the c-phase coil are connected to each other; as well as a controller that determines one of the a-phase, b-phase, and c-phase as a reference phase and alternately performs on / off control so that the on / off state of the switching element included in the leg corresponding to the reference phase and the on / off state of the switching element included in the leg corresponding to the remaining phases become complementary to each other to generate an alternating current injected into the battery, It is characterized in that The controller determines the reference phase based on the rotor angle, and The controller determines, among the angles represented in the dq stationary coordinate plane by the motor current generated when the a-phase leg is determined as the reference phase and the switching element is controlled, the motor current generated when the b-phase leg is determined as the reference phase and the switching element is controlled, and the motor current generated when the c-phase leg is determined as the reference phase and the switching element is controlled, the phase of the leg having the smallest difference between the generated motor current and the rotor angle is determined as the reference phase.

4. The battery heating system using a motor drive system according to claim 3, characterized in that: The controller controls the on / off states of a pair of switch elements included in the plurality of legs to be in a complementary relationship with each other, and The states of the switching elements connected to the positive terminal of the battery among the switching elements of the leg corresponding to the reference phase and the states of the switching elements connected to the positive terminal of the battery among the switching elements of the remaining legs are controlled to be complementary to each other.

5. The battery heating system using a motor drive system according to claim 3, characterized in that: The controller determines the a-phase as a reference phase when the rotor angle is 0° to 30°, 150° to 210°, and 330° to 360°, and alternately performs on / off control on the switching element to generate the AC current.

6. The battery heating system using a motor drive system according to claim 3, characterized in that: The controller determines the c-phase as a reference phase when the rotor angle is 30° to 90° and 210° to 270°, and the switching element is alternately on / off-controlled to generate the alternating current.

7. The battery heating system using a motor drive system according to claim 3, characterized in that: The controller determines the b-phase as a reference phase when the rotor angle is 90° to 150° and 270° to 330°, and alternately performs on / off control on the switching element to generate the AC current.

8. A battery heating method using a motor drive system, as a battery heating method using the battery heating system according to claim 3, comprising the following steps: Determining the interval to which the rotor angle belongs; determining the reference phase based on the interval to which the rotor angle belongs; as well as On / off control is performed alternately so that the on / off state of the switching element included in the leg corresponding to the reference phase and the on / off state of the switching element included in the leg corresponding to the remaining phases become complementary to each other to generate an alternating current injected into the battery.

9. The battery temperature increasing method using a motor drive system according to claim 8, characterized in that: In the judging step, when the rotor angle is 0° to 30°, 150° to 210°, and 330° to 360°, The determining step determines the a phase as a reference phase, The generating step alternately controls on / off states of a switching element included in the a-phase leg and switching elements included in the b-phase leg and the c-phase leg to generate the alternating current.

10. The battery temperature increasing method using a motor drive system according to claim 9, characterized in that: The generating step controls the states of a pair of switching elements respectively included in the a-phase leg, the b-phase leg and the c-phase leg to be in a complementary relationship with each other, And the states of the switching elements connected to the positive terminal of the battery among the switching elements included in the a-phase leg and the switching elements connected to the positive terminal of the battery among the switching elements included in the b-phase leg and the c-phase leg are controlled to be complementary to each other.

11. The battery temperature increasing method using a motor drive system according to claim 8, characterized in that: In the judging step, when the rotor angle is between 30° and 90° and between 210° and 270°, The determining step determines the c phase as a reference phase, The generating step alternately controls on / off states of a switching element included in the c-phase leg and switching elements included in the a-phase leg and the b-phase leg to generate the alternating current.

12. The battery temperature increasing method using a motor drive system according to claim 11, characterized in that: The generating step controls the states of a pair of switching elements respectively included in the a-phase leg, the b-phase leg and the c-phase leg to be in a complementary relationship with each other, And the states of the switching elements connected to the positive terminal of the battery among the switching elements included in the c-phase leg and the switching elements connected to the positive terminal of the battery among the switching elements included in the a-phase leg and the b-phase leg are controlled to be complementary to each other.

13. The battery temperature increasing method using a motor drive system according to claim 8, characterized in that: In the judging step, when the rotor angle is between 90° and 150° and between 270° and 330°, The determining step determines the b phase as a reference phase, The generating step alternately controls on / off states of a switching element included in the b-phase leg and switching elements included in the a-phase leg and the c-phase leg to generate the alternating current.

14. The battery temperature increasing method using a motor drive system according to claim 13, characterized in that: The generating step controls the states of a pair of switching elements respectively included in the a-phase leg, the b-phase leg and the c-phase leg to be in a complementary relationship with each other, And the states of the switching elements connected to the positive terminal of the battery among the switching elements included in the b-phase leg and the switching elements connected to the positive terminal of the battery among the switching elements included in the a-phase leg and the c-phase leg are controlled to be complementary to each other.

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