Power control system of a hybrid vehicle

Abstract

Power control system (12) of a hybrid vehicle (10), wherein the system comprises: a battery (28), a converter (46) that converts a DC voltage from the battery (28) into a DC voltage with a different level by switching switching elements and then outputs the converted voltage, a converter (44) that converts an output of the converter (46) into an electric motor drive current, an electric motor (24) which is driven by the electric motor drive current from the inverter (44), a control device (32) which, when there is a warm-up request for the battery (28), causes the first to fourth carrier frequencies (F1, F2, F3, F4), which are carrier frequencies in the switching control of the switching elements, to be lower than a normal carrier frequency (FA), which is a carrier frequency in the case where there is no warm-up request for the battery (28), and a machine (20), wherein the hybrid vehicle (10) drives using the electric motor (24) and / or the machine (20) as a power source, The first carrier frequency (F1) is a carrier frequency when there is a warm-up request when the machine (20) is in operation, and when there is an acceleration request. The second carrier frequency (F2) is a carrier frequency when there is a warm-up request when the machine (20) is in operation, and when there is no acceleration request. The third carrier frequency (F3) is a carrier frequency when there is a warm-up request, the machine (20) is not in operation, and when there is an acceleration request, and The fourth carrier frequency (F4) is a carrier frequency when there is a warm-up request, the machine (20) is not in operation, and when there is no acceleration request. where the first carrier frequency (F1) is smaller than the second carrier frequency (F2), the second carrier frequency (F2) is smaller than the third carrier frequency (F3), and the third carrier frequency (F3) is smaller than the fourth carrier frequency (F4).

Description

Technical field

[0001] The present invention relates to a power control system for a hybrid vehicle. More precisely, it relates to the control of a carrier frequency in a switching control system of a converter. State of the art

[0002] A hybrid vehicle is known that is equipped with an electric motor and an internal combustion engine and that operates using the electric motor and / or the internal combustion engine (machine) as a propulsion source. The hybrid vehicle can step up the DC voltage from a battery, which is a secondary battery, using a converter and then apply the voltage to an inverter, which converts the voltage into AC electrical power and then supplies the electrical power to the electric motor.

[0003] According to patent literature 1, when there is a battery warm-up requirement, a carrier frequency used for switching control of the converter is reduced compared to the case when there is no battery warm-up requirement in order to increase a ripple current, which is a current pulsation flowing through a coil of the converter, so that the warm-up of the battery connected to the coil is accelerated. Citation list

[0004] Patent literature: JP 2010 - 259 217 A Summary of the invention: Technical problem

[0005] In the configuration described in patent literature 1, the carrier frequency for the converter's switching control decreases during battery warm-up. This can increase noise, including electromagnetic interference, in the circuit comprising the battery and converter due to the increased ripple current amplitude. As a result, this can be unpleasant for vehicle passengers. In particular, when driving an electric vehicle (EV) with the engine stopped and using the electric motor as the propulsion source, the engine noise is not present in the noise audible to passengers. Therefore, any noise caused by the ripple current is more easily heard, making it even more unpleasant for passengers.

[0006] One object of the present invention is to provide a power control system for a hybrid vehicle that can accelerate the temperature rise of a battery when a battery warm-up is required and that can avoid increasing discomfort to passengers. Means to solve the problem

[0007] This problem is solved by a power control system of a hybrid vehicle as specified in claim 1. Advantages of the invention

[0008] A power control system of a hybrid vehicle according to the present invention can accelerate the temperature rise of a battery when there is a battery warm-up requirement and can avoid an increase in passenger discomfort. Brief description of the drawings Fig. Figure 1 shows a representation illustrating the general configuration of a hybrid vehicle equipped with a power control system according to an embodiment of the present invention. Fig. Figure 2 shows a flowchart illustrating a switching control method of a converter according to the embodiment of the present invention. Fig. Figure 3 shows a flowchart illustrating a setting procedure for carrier frequency adjustment according to Fig. 2 illustrates, and Fig. Figure 4 shows a graph illustrating an example of changes over time in battery temperature, converter carrier frequency, machine operating instructions, machine speed and, with respect to these, whether there is an acceleration requirement when the temperature of a battery is increased, according to the embodiment of the present invention. Detailed description of the exemplary implementations

[0009] An embodiment according to the present invention is described below with reference to the drawings. Although a motor-generator with the function of an electric motor and the function of an electric power generator is described below as an electric motor, the electric motor need not have the function of the electric power generator. Although in the case described below a boost converter (boost converter) with boost / dim functions is used as a converter, a converter that simply has the boost function can be used. Components similar to those according to Fig. Items 1 and 1 are described below with reference to the same reference numerals.

[0010] Fig. Figure 1 shows the general configuration of a hybrid vehicle 10 equipped with a power control system 12 according to the exemplary embodiment. The hybrid vehicle comprises the power control system 12, a deceleration device (reduction device, reduction gear) 14, and drive wheels (e.g., front wheels) 18 connected to a drive shaft 16. The power control system 12 further comprises an internal combustion engine (engine) 20, a first motor-generator 22, a second motor-generator 24, a power-sharing mechanism 25, a power control unit (PCU) 26, a battery 28, and an electronic control unit (ECU) 32, which is a control device. The hybrid vehicle 10 operates using the engine 20 and / or the second motor-generator 24 as a power source.In the following, the first motor generator 22 will be referred to as the first MG22, and the second motor generator 24 will be referred to as the second MG24.

[0011] Based on a control signal Si1 from the ECU 32, the fuel supply or the like is controlled, thus controlling the drive of the machine. A machine speed sensor 34 for detecting the rotational speed Ne of a crankshaft is attached to the machine 20. In this description, "rotational speed" means one revolution per unit of time, for example, per minute.

[0012] The first MG22 is electrically connected to the battery 28 and is a three-phase synchronous electric power generator with an electric power generation function, producing electrical power when substantially driven by the machine 20. The first MG22 also has a motor function for starting the machine 20. When the first MG22 is used as the electric power generator, at least some of the torque from the machine 20 is transferred to a rotating shaft of the first MG22 via the power-sharing mechanism 25 described below. Electrical power generated by the first MG22 is supplied to the battery 28 via the PCU 26, thus charging the battery 28. A first rotation sensor 36, which detects an angle of rotation or a rotational speed Nw1 of the rotating shaft of the first MG22, is attached to the first MG22.

[0013] The second MG24 is electrically connected to the battery 28, essentially functions as a traction motor, and is a three-phase synchronous motor driven by electrical power supplied from the battery 28. When the second MG24 is driven, it powers the drive wheels 18, generating propulsion for the vehicle. The second MG24 also functions as an electric power generator for regenerative braking, enabling regenerative braking when the vehicle decelerates. Electrical power generated by the second MG24 is also supplied to the battery 28 via the PCU 26, thus charging the battery 28. A second rotation sensor 38, which detects the rotation angle or speed Nw2 of the second MG24's rotating shaft, is attached to the second MG24. Induction motors or any other type of electric motor can be used for the first and second MGs.

[0014] Signals indicating the measured values ​​Ne, Nw1 and Nw2 from the machine speed sensor 34, the first rotation sensor 36 and the second rotation sensor 38 are sent to the ECU 32. The ECU 32 calculates the rotational speeds Nw1 and Nw2 upon receiving the measured values ​​of the rotational angles.

[0015] The power-sharing mechanism 25 is constructed from a planetary gear mechanism. For example, the planetary gear mechanism includes a sun gear, a plurality of pinions, a carrier, and a ring gear. The sun gear is connected to the end of the hollow drive shaft of the first MG22. The pinions mesh with both the ring gear and the sun gear and are connected to the drive shaft of the machine 20 via the carrier. Each pinion is connected to the end of the carrier to enable it to rotate about its axis and about the carrier's central axis. The ring gear is connected to an output shaft 40, and the output shaft 40 is coupled to the drive shaft of the second MG24. The output shaft 40 can be coupled to the drive shaft of the second MG24 via a deceleration (reduction) mechanism, including another planetary gear mechanism not shown.The output shaft 40 is connected via the deceleration device 14 to the drive shaft 16, which is coupled to the drive wheels 18. The power distribution mechanism 25 divides the power from the machine 20 into one path to the output shaft 40 and one path to the first MG22.

[0016] The PCU 26 is electrically connected between the first MG22, the second MG24, and the battery 28. The PCU 26 comprises a first inverter 42, a second inverter 44, and a converter 46, which is a DC-DC converter. The converter 46 is controlled by a control signal Si2 from the ECU 32, and each of the inverters 42 and 44 is controlled by a control signal Si3 from the ECU 32. The converter 46 comprises two switching elements Q1 and Q2, provided in an upper branch and a lower branch, two diodes D1 and D2, each connected in parallel to the switching elements Q1 and Q2 to allow opposing electrical currents to pass, and an inductor L, one end of which is connected between the switching elements Q1 and Q2. Transistors such as IGBTs are used as the switching elements Q1 and Q2. The converter 46 is connected between the battery 28 and the inverters 42 and 44.Converter 46 has the function of boosting a DC voltage VL applied by battery 28 by switching the switching elements Q1 and Q2 to convert the DC voltage VL into a DC voltage with a different level, and then outputting a boosted DC voltage VH to inverters 42 and 44 when controlled by a boost instruction from ECU 32. Converter 46 also has the function of stepping down the DC voltage on the output side (VH side) and then outputting the DC voltage VL to battery 28 when controlled by a step-down instruction from ECU 32. As a result, battery 28 is charged.

[0017] The first converter 42 converts the DC voltage VH applied by the converter 46 into an AC voltage and outputs the AC voltage to the first MG22, driving the first MG22. In this case, the first converter 42 converts the output current of the converter 46 into a driving current for the first MG22. The first MG22 is driven by the driving current from the first converter 42. The first converter 42 also has the function of converting an AC voltage obtained when the first MG22 has generated electricity (current, electrical power) in response to the drive of the machine 20 into a DC voltage and outputting the DC voltage to the converter 46.

[0018] The second inverter 44 converts the DC voltage VH applied by the converter 46 into an AC voltage and then outputs the AC voltage to the second MG24, driving the second MG24. In this case, the second inverter 44 converts the output current of the converter 46 into a drive current for the second MG24. The second MG24 is driven by the drive current from the second inverter 44. The second inverter 44 also has the function of converting an AC voltage generated during regenerative braking of the hybrid vehicle 10 into a DC voltage and outputting the DC voltage to the converter 46.

[0019] The first inverter 42 and the second inverter 44 each have switching elements provided in upper and lower branches for the U, V, and W phases, respectively. The switching of each switching element is controlled by the control signal Si2 from the ECU 32. The upper and lower three-phase branches of the first inverter 42 are electrically connected to the input terminals of the first MG22 of the respective phases via power lines, and a first motor current sensor (not shown) for detecting motor current is attached to the two-phase or three-phase power lines. A second motor current sensor (not shown) is also attached to two-phase or three-phase power lines that connect the second inverter 44 to the second MG24. A signal indicating the detected value from each motor current sensor is sent to the ECU 32.

[0020] Battery 28 is a secondary battery, which may be a nickel-metal hydride battery, a lithium-ion battery, or any other type. A system relay (not shown) is provided between battery 28 and inverter 46, and the on / off operation of the system relay is controlled by the ECU 32. Smoothing capacitors may be connected between inverter 46 and battery 28, and between inverter 46 and each of inverters 42 and 44. A battery temperature sensor 48 detects a temperature TB of battery 28 and sends a signal indicating the detected temperature TB to the ECU 32. A battery current sensor and a battery voltage sensor (not shown) are each provided to detect an output current and an output voltage of battery 28, and signals indicating the detected values ​​of the battery current and battery voltage sensors are sent to the ECU 32.

[0021] A voltage sensor 50 detects the low-voltage side VL of the converter 46 and sends a signal indicating the voltage VL to the ECU 32. A voltage sensor 52 detects the high-voltage side voltage VH of the converter 46 and sends a signal indicating the high-voltage side voltage VH to the ECU 32.

[0022] An accelerator pedal position sensor 54 detects the accelerator pedal position AP and sends a signal indicating the accelerator pedal position AP to the ECU 32. A drive wheel rotation sensor 56 detects a rotation angle or speed Hs of the drive wheels 18 and sends a signal indicating the speed Hs to the ECU 32. The ECU 32 calculates an estimated vehicle speed based on the speed Hs. Alternatively, the ECU 32 can calculate the estimated vehicle speed based on the rotation angle of the second MG24 or the detected speed Nw2. Alternatively, the ECU 32 can calculate the vehicle speed by using the detected value of a rotation sensor (not shown) to detect a rotation angle or speed Vs of driven wheels (for example, rear wheels).

[0023] The ECU 32 comprises a microcomputer with a CPU and memory. Although only one ECU 32 is shown in the example, the ECU 32 can be suitably divided into components that are electrically connected to each other by a signal cable. The ECU 32 comprises a battery warm-up request section 60, a machine evaluation section 62, an acceleration request evaluation section 64, a carrier frequency setting section 66, and a converter control section 68. The converter control section 68 controls the switching operation of the switching elements of the converter 46 based on the set frequency, which is set by the carrier frequency setting section 66. The ECU 32 also controls the operation of the inverters 42 and 44.The battery warm-up requirement section 60, the machine operation evaluation section 62, the acceleration requirement evaluation section 64 and the carrier frequency setting section 66 are described below.

[0024] During drive control, the ECU 32 calculates a target vehicle torque Tr* and a target machine output power Pe* based on the accelerator pedal position AP or the vehicle speed and accelerator pedal position AP, and calculates a target speed Ne* and a target torque Te* of machine 20 based on a preset characteristic map. The ECU 32 calculates a target speed Nw1* and a target torque Tr1* of the first MG22 and a target torque Tr2* of the second MG24 based on the target speed Ne*, the speed Nw2 of the second MG24, and the speed Nw1 of the first MG21. The target speed Ne*, target torque Te*, target speed Nw1*, target torque Tr1*, and target torque Tr2* can be derived from a characteristic map pre-stored in a memory unit (not shown) based on the accelerator pedal position AP or the accelerator pedal position AP and the vehicle speed.

[0025] The ECU 32 controls the machine 20 according to the control signal Si1 such that the calculated target speed Ne* and the target torque Te* of the machine 20 are achieved. The ECU 32 controls the converter 46 and the inverters 42 and 44 using the converter control section 68 and an inverter control section (not shown) of the ECU 32 according to the control signals Si2 and Si3 such that the calculated target speed Nw* and the calculated target torque Tr1* of the first MG22 and the target torque Tr2* of the second MG24 are achieved.

[0026] In this case, the ECU 32 calculates a target voltage VH*, which is an input voltage from each of the inverters 42 and 44 and an output voltage from the converter 46, based on the target torques Tr1* and Tr2*, the target speed Nw1*, and the speed Nw2. For example, the target voltage VH* can be the higher of the voltages required by each inverter 42 and 44. The converter 46 controls the switching of the switching elements Q1 and Q2 such that the voltage sensing value VH can correspond to the target voltage VH*. In this case, when one switching element Q1 (or Q2) of the switching elements Q1 and Q2 is switched on, the other switching element Q2 (or Q1) is switched off. This process is repeated so that the switching elements are alternately switched on and off in reverse order over a dead time during which both switching elements are off. In this case, as will be explained later with reference to Fig. As described in Figure 2, the ECU 32 receives a control signal based on the carrier frequency, which is the frequency of carrier signal waveforms, and a duty cycle (a relative on-time), and drives the switching elements Q1 and Q2 by means of the control signal. In the converter 46, the voltage VH increases if the on-time of switching element Q2 in the lower branch is increased, and the voltage VH decreases if the on-time of switching element Q1 in the upper branch is increased.

[0027] The ECU 32 calculates a state of charge (SOC), which represents the charge level of the battery 28, based on the measured value from the battery current sensor (not shown) and / or the battery voltage sensor (not shown). The calculated SOC value is used to control the switching between electric vehicle (EV) and hybrid vehicle (HV) operating modes.

[0028] The ECU 32 controls machine 20, the first MG22, and the second MG24 to drive the vehicle, switching between EV mode (electric vehicle drive mode) and HV mode. In EV mode, the second MG24 is driven while the machine is stopped, serving as a drive source to propel the vehicle. In HV mode, at least machine 20 is driven to propel the vehicle. In this case, the first MG22 generates electricity (current, electrical power) by driving machine 20. The EV and HV modes are switched depending on whether a predefined condition is met.For example, the operating mode is switched to HV mode if, during EV mode, the calculated value of the SOC reaches a predetermined lower limit or less. During HV mode, a driver activates an EV drive instruction section 70, and if EV mode is selected, the operating mode switches to EV mode, provided a predetermined EV mode condition is met. During HV mode, the operating mode also switches to EV mode if the calculated value of the SOC reaches a predetermined upper limit or more. EV drive instruction section 70 is, for example, a push button or switch for specifying EV mode. When activated by a user, EV drive instruction section 70 sends a signal indicating this activation to the ECU 32.

[0029] When a battery warm-up request is received, the ECU 32 sets the carrier frequency of the converter 46 to one of frequencies F1, F2, F3, and F4 that is lower than the carrier frequency FA that would be used when there is no battery warm-up request. Specifically, the battery warm-up request section 60 issues a battery warm-up request when a predetermined battery warm-up request condition is met. For example, if the battery temperature TB is lower than a preset temperature T0 (TB <T0), und wenn eine vorab eingestellte Batterieaufwärmvoraussetzung erfüllt ist, gibt der Batterieaufwärmanforderungsabschnitt 60 eine Batterieaufwärmanforderung aus.The "battery warm-up condition" is met, for example, if the state of charge (SOC) in battery 28 is the predetermined lower limit or greater, if the battery voltage (VL) is within a predetermined range, and if the temperature measured by a temperature sensor (not shown) used to measure the temperature of each of the inverters 42 and 44 is a predetermined temperature or less. Otherwise, the "battery warm-up condition" is not met.

[0030] Machine operation assessment section 62 assesses whether machine 20 is "in operation" or "not in operation". In this assessment, a detected value Ne from the machine speed sensor 34, sent to the ECU 32, is used to assess whether machine 20 is "not in operation" if the machine speed Ne is zero, or otherwise to assess whether machine 20 is "in operation".

[0031] The acceleration request evaluation section 64 assesses whether there is a preset “acceleration request” of the hybrid vehicle 10. For example, in the hybrid vehicle 10, the vehicle speed is determined by the rotational speed Nw2 of the second MG24, so that the acceleration request evaluation section 64 assesses that there is an acceleration request if an increase ΔNw2 of the rotational speed Nw2 of the second MG24 per unit of time Δt is a preset predetermined value K or greater (ΔNw2 / Δt≥K), whereas otherwise the acceleration request evaluation section 64 assesses that there is no acceleration request.As another example, the acceleration request evaluation section 64 can evaluate that there is an acceleration request if, according to the accelerator pedal position sensor 54's reading, the accelerator pedal actuation rate per unit time Δt is a predetermined value or greater; otherwise, the acceleration request evaluation section 64 can evaluate that there is no acceleration request. As a further example, the vehicle speed calculated from the drive wheel rotation sensor 56 or the reading from a vehicle speed sensor can be used to evaluate that there is an acceleration request if the increase in vehicle speed per unit time Δt is a predetermined value or greater; otherwise, it can be used to evaluate that there is no acceleration request.

[0032] The carrier frequency setting section 66 sets the carrier frequency of the converter 46 based on whether there is a warm-up requirement for the battery 28, based on a machine operating state, and based on whether there is currently an acceleration requirement. Specifically, the carrier frequency setting section 66 performs the setting such that the carrier frequencies F1, F2, F3, and F4 can be lower than the normal frequency FA when there is a warm-up requirement for the battery 28, which is the carrier frequency when there is no warm-up requirement for the battery 28 (F1, F2, F3, F4 < FA). The normal frequency FA will be the carrier frequency after the battery warm-up is complete, if the battery 28 is only warmed up once.

[0033] When there is a warm-up requirement for battery 28, the carrier frequency setting section 66 adjusts the settings such that, when machine 20 is operating, the carrier frequencies F1 and F2 are lower than the carrier frequencies F3 and F4 when machine 20 is not operating (F1, F2 < F3, F4). Thus, as described later, the temperature rise of battery 28 can be accelerated when there is a warm-up requirement for battery 28, and an increase that could cause discomfort to vehicle passengers can be avoided.

[0034] Furthermore, if there is a warm-up request for battery 28 and machine 20 is in operation, the carrier frequency setting section 66 sets the carrier frequency such that, in the case where there is a vehicle acceleration request, the carrier frequency F1 is lower than the carrier frequency F2 in the case where there is no vehicle acceleration request (F1 <F2). Falls es eine Aufwärmanforderung für die Batterie 28 gibt und falls die Maschine 20 nicht in Betrieb ist, stellt der Trägerfrequenzeinstellungsabschnitt 66 die Trägerfrequenz derart ein, dass die Trägerfrequenz F3 in dem Fall, in dem es eine Fahrzeugbeschleunigungsanforderung gibt, niedriger als die Trägerfrequenz F4 in dem Fall sein kann, in dem es keine Fahrzeugbeschleunigungsanforderung gibt (F3<F4).

[0035] The converter control section 68 controls the switching of the switching elements Q1 and Q2 of the converter 46 on the basis of the carrier frequency set by the carrier frequency setting section 66, the detected voltage VH and the set voltage VH*.

[0036] Fig. Figure 2 shows a flowchart illustrating a converter control method during the drive control using the power control system 12 according to the present embodiment. Fig. Figure 3 shows a flowchart illustrating a setting procedure for carrier frequency adjustment according to Fig. 2 illustrated.

[0037] In step S10, the ECU 32 sets the normal frequency FA as an initial value for the carrier frequency. In step S12, the detected voltage VH and the target voltage V* are then supplied to the ECU 32. Hereafter, steps "S" are abbreviated as "S2". In S14, the carrier frequency is set by the carrier frequency setting section 66. The carrier frequency setting is described later with reference to... Fig. 3 described.

[0038] If the carrier frequency is set in S14, a duty cycle used for switching control of the converter 46 is set in S16 based on the detected voltage VH and the target voltage VH*, and a control signal is generated based on the duty cycle and the carrier frequency (S18). In S20, the converter control section 68 outputs a control signal to the converter 46 based on the control signal described above, controls the switching of the converter 46, and returns to S12 at each predetermined control period to repeat the process.

[0039] The following is a procedure for setting the carrier frequency with reference to Fig. 3 described. During carrier frequency setting, a carrier frequency is selected from a total of 5 carrier frequencies, namely the first, second, third, and fourth frequencies F1, F2, F3, and F4, and the normal frequency FA. The carrier frequencies are set in ascending order from F1, F2, F3, F4, and FA (F1 <F2<F3<F4<FA). Die normale Frequenz FA ist eine Frequenz außerhalb des menschlichen Hörbereichs, beispielsweise 20 kHz oder mehr. Die ersten, zweiten, dritten und vierten Frequenzen F1, F2, F3 und F4 sind Frequenzen innerhalb des hörbaren Frequenzbereichs, beispielsweise 15 kHz oder weniger. Die normale Frequenz kann beispielsweise 10 kHz innerhalb des hörbaren Frequenzbereichs sein, und die ersten, zweiten, dritten und vierten Frequenzen F1, F2, F3 und F4 können niedriger als 10 kHz sein.

[0040] First, the carrier frequency setting section 66 assesses whether the battery warm-up request section 60 has issued a battery warm-up request, and thereby assesses whether there is a battery warm-up request (S30).

[0041] If S30 determines that there is no battery warm-up request, the normal frequency FA is set as the carrier frequency in S32. Conversely, if S30 determines that there is a battery warm-up request, the carrier frequency setting section 66 uses the machine operation assessment section 62 in S34 to determine whether the machine 20 is in operation or not. If S34 determines that the machine 20 is in operation, the carrier frequency setting section 66 uses the acceleration request assessment section 64 in S36 to determine whether there is a vehicle acceleration request. If S36 determines that there is an acceleration request, the carrier frequency is set to the lowest (first) frequency F1 from the five carrier frequencies F1, F2, F3, F4, and FA (S38).If there is no acceleration request, the carrier frequency is set to the second-lowest frequency F2 that is higher than the lowest frequency F1 (F2 > F1) (S40). For example, if the carrier frequency up to now has been the normal frequency FA, ​​the carrier frequency will be changed in S38 or S40 to the lowest frequency F1 or the second-lowest frequency F2.

[0042] If, on the other hand, S34 determines that machine 20 is not in operation, the carrier frequency setting section 66 uses the acceleration request assessment section 64 in S42 to determine whether there is an acceleration request. If there is an acceleration request, the carrier frequency is set to the third lowest frequency F3 that is higher than the second lowest frequency F2 (F3 > F2) (S44). If S42 determines that there is no acceleration request, the carrier frequency setting section 66 sets the carrier frequency to the fourth lowest frequency F4 that is higher than the third lowest frequency F3 (F4 > F3) (S46).

[0043] Once the carrier frequencies are set in S38, S40, S44, S46 or S32, processing returns to S14 in Fig. 2 back, and the processing is carried out in S14 to S20, so that the switching of the converter 46 is controlled.

[0044] Fig. Figure 4 shows an example of temporal changes in the battery temperature TB, the carrier frequency of the converter 46, machine operating instructions, the machine speed, and whether there is an acceleration request when the temperature of the battery 28 is elevated, according to the embodiment. The "HV operating mode," in which the machine 20 is operated, is carried out from time t1 to t3. The "EV operating mode," in which the operation of the machine 20 is stopped and in which the vehicle is driven by the second MG24, is carried out from time t3 to time t5. Initially, the normal frequency FA is set in an initial condition at the start of operation. However, if the battery temperature TB is lower than the predetermined temperature T0, the battery warm-up condition is met, so a "battery warm-up request" is issued.When the driver presses the accelerator pedal, a machine operating instruction is issued, the machine speed increases, and the vehicle begins to move. If it is then determined that there is a vehicle acceleration request, the carrier frequency is set to the lowest frequency F1 at time t1.

[0045] If, at time t2, it is determined that there is no vehicle acceleration demand because a constant accelerator pedal input is maintained, the carrier frequency is changed to the second-lowest frequency F2, which is higher than the lowest frequency F1. The operation of machine 20 is then stopped at time t3, and if EV drive is then initiated, the carrier frequency is changed to the fourth-lowest frequency F4. If, at time t4, it is determined that there is an acceleration demand in the EV drive, the carrier frequency is changed to the third-lowest frequency F3, which is lower than the fourth-lowest frequency F4. The carrier frequency thus becomes lower than the normal frequency FA, ​​causing the temperature of battery 28 to rise as described below, and the battery temperature TB gradually increases.The battery temperature TB then assumes the predetermined temperature T0 or higher at time T5 and there is no longer a battery warm-up requirement, so the carrier frequency is changed to the normal frequency FA and the normal drive control of the vehicle is carried out using the normal frequency FA.

[0046] In the power control system 12 described above, when there is a warm-up requirement for battery 28, the carrier frequency is lower than the normal frequency FA when there is no warm-up requirement. This results in a ripple current, which follows the carrier frequency, being generated in the current flowing through coil L (coil current), and the amplitude of the ripple current increases. The ripple current is also generated in a battery current, which is an input / output current of battery 28, and the heat value of the internal resistance of battery 28 increases, thus raising the temperature of battery 28. Consequently, the temperature of battery 28 can be raised by changing the carrier frequency from the normal frequency FA to a lower frequency, and the temperature increase of battery 28 can be further accelerated at a lower carrier frequency.

[0047] Conversely, if the carrier frequency is low, interference noise, including electromagnetic interference (noise), increases in the circuits with the battery 28 and the transducer 46 in proportion to the increase in the amplitude of the ripple current. If the carrier frequency is within the audible frequency range, the proportion of people who can hear a given frequency is higher at a lower frequency. According to the present embodiment, the carrier frequencies F1 and F2, at which the machine 20 is in operation, are set lower than the third and fourth lowest frequencies F3 and F4, at which the machine 20 is not in operation when there is a warm-up requirement for the battery 28.Thus, even if the frequency of the noise decreases due to the ripple current and is therefore easier to hear, the ratio of the noise due to the increase in the ripple current to the total noise resulting from the vehicle is lower due to the noise of the machine 20, so that the noise caused by the ripple current does not necessarily become a noise that is unpleasant for vehicle passengers.

[0048] In contrast, the ratio of the noise caused by the ripple current to the total noise resulting from the vehicle is higher when the machine 20 is not in operation. However, the frequency of this noise caused by the ripple current is high, which is why this noise does not necessarily become an unpleasant noise for the vehicle passengers. For example, if the third and fourth lowest frequencies F3 and F4 range from 10 to 15 kHz, which are relatively high in the audible frequency range, the proportion of people who cannot hear them is higher than at a lower frequency, which does not necessarily lead to an unpleasant noise. As a result, the temperature rise of the battery 28 can be accelerated if there is a warm-up requirement for the battery 28, and an increase in discomfort for the vehicle passenger can be limited.

[0049] The carrier frequency decreases further when the machine 20 is in operation, or when the vehicle accelerates during the operation of the machine 20, thus accelerating the temperature rise of the battery 28, and increasing road noise (rolling noise) due to the increase in vehicle speed resulting from the acceleration. Therefore, the ripple current-based noise resulting from the reduction in carrier frequency does not necessarily become an unpleasant noise for the vehicle passengers. Furthermore, the acceleration during the operation of the machine 20 increases the machine speed and thus increases the noise based on the machine noise, so that the ratio of the noise based on the increase in ripple current to the total noise resulting from the vehicle becomes lower. Thus, the temperature rise of the battery 28 can be accelerated more efficiently.In the case described above, the carrier frequency is changed depending on whether there is an acceleration request, both when machine 20 is running and when it is not running. However, the carrier frequency can be changed depending on whether there is an acceleration request only when machine 20 is running or only when it is not running.

[0050] Although in the case described above the carrier frequency is changed depending on whether there is an acceleration request, the carrier frequency can remain unchanged regardless of whether there is an acceleration request. In this case, if there is a battery warm-up request and if machine 20 is running, the lowest frequency F1A, which is lower than the normal frequency FA, ​​is set as the carrier frequency. If machine 20 is not running, the second-lowest frequency F2A, which is higher than the lowest frequency F1A but lower than the normal frequency (F2A > F1A), is set as the carrier frequency.

[0051] In the representation of Fig. 4. If the carrier frequency is changed, this change is implemented immediately. In contrast, if the carrier frequency is changed, it can be gradually increased or decreased at a constant given rate of increase or decrease over a predetermined control period until the change is complete, so that the carrier frequency can be gradually changed to increase or decrease, and the converter 46 can be controlled in each control period. In this case, for example, the carrier frequency is gradually changed from frequency FA to frequency F1, as indicated by a dashed line P1 in Fig. The frequency is indicated as 4 and gradually changes from frequency F3 to frequency FA, ​​as indicated by a dashed line P2. Although not shown, the same applies to changes in other frequencies.

[0052] The ECU 32 can perform such control that the operation of the first MG22 and the second MG24 is stopped for no-load operation of the machine 20 when there is a warm-up requirement for the battery 28, and the switching of the converter 46 is controlled using a carrier frequency that is lower than the normal frequency FA. Accordingly, the first MG22 and the second MG24 do not generate any electrical power during the warm-up of the battery 28, and charging of the battery 28 with excessive electrical power can be effectively prevented. Reference symbol list

[0053] 10: Hybrid vehicle, 12: Power control, 14: Deceleration device, 16: Drive shaft, 18: Drive wheels, 20: Machine, 22: First motor generator (first MG), 24: Second motor generator (second MG), 25: Power sharing mechanism, 26: PCU, 28: Battery, 32: ECU, 34: Machine speed sensor, 36: First rotation sensor, 38: Second rotation sensor, 40: Output shaft, 42: First inverter, 44: Second inverter, 46: Converter, 48: Battery temperature sensor, 50, 52: Voltage sensors, 54: Accelerator pedal position sensor, 56: Drive wheel rotation sensor, 60: Battery warm-up request section, 62: Machine operation evaluation section, 64: Acceleration request evaluation section, 66: Carrier frequency setting section, 68: Converter control section, 70: EV drive instruction section.

[0054] As described above, a power control system comprises a battery, a converter that transforms the DC voltage from the battery into a DC voltage at a different level by switching switching elements, a second converter, a second motor unit (MG) which is an electric motor, a machine, and an electronic control unit (ECU) which is a control device. When there is a battery warm-up request, the ECU causes the carrier frequency used for switching the switching elements to be lower than the carrier frequency used when there is no battery warm-up request. When there is a warm-up request, the ECU causes the carrier frequency at which the machine is operating to be lower than the carrier frequency at which the machine is not operating.

Claims

[1] Power control system (12) of a hybrid vehicle (10), wherein the system comprises: a battery (28), a converter (46) that converts a DC voltage from the battery (28) into a DC voltage with a different level by switching switching elements and then outputs the converted voltage, a converter (44) that converts an output of the converter (46) into an electric motor drive current, an electric motor (24) which is driven by the electric motor drive current from the inverter (44), a control device (32) which, when there is a warm-up request for the battery (28), causes the first to fourth carrier frequencies (F1, F2, F3, F4), which are carrier frequencies in the switching control of the switching elements, to be lower than a normal carrier frequency (FA), which is a carrier frequency in the case where there is no warm-up request for the battery (28), and a machine (20), wherein the hybrid vehicle (10) drives using the electric motor (24) and / or the machine (20) as a power source, The first carrier frequency (F1) is a carrier frequency when there is a warm-up request when the machine (20) is in operation, and when there is an acceleration request. The second carrier frequency (F2) is a carrier frequency when there is a warm-up request when the machine (20) is in operation, and when there is no acceleration request. The third carrier frequency (F3) is a carrier frequency when there is a warm-up request, the machine (20) is not in operation, and when there is an acceleration request, and The fourth carrier frequency (F4) is a carrier frequency when there is a warm-up request, the machine (20) is not in operation, and when there is no acceleration request. where the first carrier frequency (F1) is smaller than the second carrier frequency (F2), the second carrier frequency (F2) is smaller than the third carrier frequency (F3), and the third carrier frequency (F3) is smaller than the fourth carrier frequency (F4).

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