JP2013055853A - Power supply control device of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply control device of an electric vehicle which can suppress a rush current flowing at the start of power supply from a plurality of power accumulation devices mounted to a vehicle, and can effectively utilize power accumulated in the plurality of power accumulation devices.SOLUTION: The power supply control device of the electric vehicle 5 comprises: the power accumulation device 100; the power accumulation device 150; a converter 110 for executing DC voltage conversion in both directions between the power accumulation device 100 and a power line HPL; a relay RL1 connected between the power accumulation device 150 and the power line HPL; a relay RL2 connected between the power accumulation device 150 and a grounding line NL1; and a control device 300 which on/off-controls the relays RL1, RL2 according to operation states of electric motors MG1, MG2. When the control device 300 turns on the relay RL2, the control device turns on the relay RL1 after the deviation of a voltage of the power line HPL with respect to an output voltage of the power accumulation device 150 is lowered to a prescribed threshold by the DC voltage conversion of the converter 110.

Description

  The present invention relates to a power supply control device for an electric vehicle, and more particularly to a power supply control device for an electric vehicle equipped with a plurality of power storage devices.

  As a power supply control device applied to an electric vehicle, for example, Japanese Patent Laying-Open No. 2007-209114 (Patent Document 1) discloses a high-voltage traveling battery and an auxiliary battery that is charged and discharged at a lower voltage than the traveling battery. An inverter circuit in which the voltage from the traveling battery is input via the open / close switch, a smoothing capacitor provided in parallel between the traveling battery and the inverter circuit, and an output voltage of the auxiliary battery are boosted to an inverter A configuration including a DC / DC converter as an input voltage of a circuit is disclosed.

  In this patent document 1, before starting the energization from the running battery to the inverter circuit, the output voltage from the DC / DC converter is controlled to precharge the smoothing capacitor. Then, the battery for traveling and the inverter circuit are electrically connected by closing the open / close switch after precharging the smoothing capacitor.

JP 2007-209114 A JP 2007-318878 A JP 2006-121874 A

  In the above-mentioned Patent Document 1, damage to the contacts of the open / close switch is prevented by closing the open / close switch after precharging the smoothing capacitor. However, in the configuration of Patent Document 1, after the open / close switch is closed, the DC side voltage of the inverter circuit is fixed to the output voltage of the traveling battery. Therefore, the DC side voltage of the inverter circuit cannot be variably controlled. Furthermore, since the driving force is generated from the traveling motor using only the traveling battery that is always connected to the inverter circuit, there is a problem that the cruising distance of the electric vehicle is limited.

  One solution for increasing the cruising distance of an electric vehicle is to use a plurality of traveling batteries by connecting a plurality of traveling batteries in parallel to the inverter circuit. However, in this configuration, in order to variably control the DC side voltage of the inverter circuit, it is necessary to provide a converter in association with each traveling battery, which increases power loss and increases the size and cost of the power supply system. Invite to rise. Therefore, it is necessary to simply and efficiently construct a mechanism for effectively using a plurality of traveling batteries while ensuring a variable control function of DC voltage by a converter.

  Furthermore, in this configuration, it is necessary to suppress the inrush current that flows when each of the plurality of traveling batteries starts to supply power to the inverter circuit.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to suppress an inrush current flowing at the start of power supply from a plurality of on-vehicle power storage devices, and the plurality of power storage devices. It is providing the power supply control apparatus of the electric vehicle which can use effectively the electric power stored in.

  In one aspect of the present invention, a power supply control device for an electric vehicle equipped with an electric motor for generating vehicle driving force includes: a first power storage device; a second power storage device; and power input / output to / from the motor. A power line for transmitting power, a converter for performing bidirectional DC voltage conversion between the first power storage device and the power line, and a first power source connected between the second power storage device and the power line A switch, a second switch connected between the second power storage device and the ground line, and a control device for controlling on / off of the first and second switches according to the operating state of the electric motor; Is provided. When the control device turns on the second switch, the first switch is operated after reducing the deviation of the voltage of the power line with respect to the output voltage of the second power storage device to a predetermined threshold value by DC voltage conversion of the converter. Turn on.

  Preferably, the control device sets the voltage command value of the power line according to the operating state of the electric motor, and the first and first according to the comparison result between the output voltage of the second power storage device and the voltage command value. And an opening / closing control means for controlling on / off of the two switches.

  Preferably, the setting means calculates the necessary minimum voltage of the power line according to the operating state of the electric motor, and sets the voltage command value in a range equal to or higher than the necessary minimum voltage. The switching control means turns on the first and second switches when the output voltage of the second power storage device is equal to or higher than the voltage command value, while the output voltage of the second power storage device is lower than the voltage command value. Sometimes the first and second switches are turned off.

  Preferably, the control device controls the DC voltage conversion of the converter so that the voltage of the power line falls within an allowable range defined by the output voltage of the second power storage device and a predetermined threshold value. Further included. The switching control means turns on the first and second switches when the voltage of the power line falls within the allowable range by the voltage conversion control means.

  Preferably, the rated value of the output voltage of the first power storage device is lower than the rated value of the output voltage of the second power storage device.

  According to the present invention, in an electric vehicle equipped with a plurality of power storage devices, it is possible to effectively utilize the power stored in the plurality of power storage devices while suppressing inrush current at the start of power supply from each power storage device. .

It is a schematic block diagram of the electric vehicle carrying the power supply control device according to embodiment of this invention. It is a conceptual diagram which shows the relationship between a system voltage and the operation possible area | region of a motor generator. It is a flowchart explaining an example of the control processing of the power supply control device by embodiment of this invention. It is a timing chart for demonstrating the control processing of the relay and converter in a control apparatus. It is a figure explaining the structural example of the control block for implement | achieving control of the relay and converter in a control apparatus. It is the flowchart which showed the control processing procedure for implement | achieving control of the relay and converter in a control apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic configuration diagram of an electric vehicle 5 equipped with a power supply control device according to an embodiment of the present invention.

  Referring to FIG. 1, electric vehicle 5 is typically a hybrid vehicle, and includes an internal combustion engine (engine) 220 and an electric motor (MG: Motor Generator), and controls the driving force from each to an optimal ratio. Then run. Electric vehicle 5 is equipped with a plurality of (for example, two) power storage devices for supplying electric power to the motor generator. These power storage devices can be charged by receiving the power generated by the operation of the engine 220 when the system of the electric vehicle 5 is activated. It is electrically connected to a power source and can be charged.

  In the present embodiment, an example in which electric vehicle 5 includes two motor generators and corresponding inverters will be described. However, even when one motor generator and inverter are included, three or more motor generators and inverters are included. The present invention can be applied even when provided.

  The electric vehicle 5 includes a load 10, a power supply system 20, and a control device 300. Load 10 includes an inverter 120, motor generators MG1 and MG2, a power split mechanism 250, an engine 220, and drive wheels 260.

  Motor generators MG1 and MG2 are AC rotating electric machines, for example, permanent magnet type synchronous motors including a rotor having a permanent magnet embedded therein and a stator having a three-phase coil Y-connected at a neutral point.

  Output torques of motor generators MG1 and MG2 are transmitted to drive wheels 260 through power split mechanism 250 to cause electric vehicle 5 to travel. Motor generators MG <b> 1 and MG <b> 2 can generate electric power using the rotational force of drive wheels 260 during regenerative braking of electric vehicle 5. Then, the generated power is converted into charging power for power storage device 100 and / or 150 by converter 110 and inverter 120.

  Motor generators MG 1 and MG 2 are also coupled to engine 220 via power split mechanism 250. Control device 300 operates motor generators MG1 and MG2 and engine 220 in cooperation to generate a necessary vehicle driving force. Further, motor generators MG1 and MG2 can generate electric power by rotating engine 220, and can use this generated electric power to charge power storage devices 100 and / or 150. In the present embodiment, motor generator MG2 is mainly used as an electric motor for driving drive wheels 260, and motor generator MG1 is mainly used as a generator driven by engine 220. That is, motor generator MG2 corresponds to an “electric motor” for generating vehicle driving force.

  Power split mechanism 250 includes a planetary gear mechanism (planetary gear) in order to distribute the power of engine 220 to drive wheels 260 and motor generator MG1.

  Current sensors 230 and 240 detect motor currents (that is, inverter output currents) MCRT1 and MCRT2 flowing in motor generators MG1 and MG2, respectively, and output the detected motor currents to control device 300. Since the sum of the instantaneous values of the currents iu, iv, and iw in the U, V, and W phases is zero, the current sensors 230 and 240 are motor currents for two phases of the U, V, and W phases ( For example, it is sufficient to arrange to detect the V-phase current iv and the W-phase current iw).

  Rotation angle sensors (for example, resolvers) 270 and 280 detect rotation angles θ1 and θ2 of motor generators MG1 and MG2, respectively, and send the detected rotation angles θ1 and θ2 to control device 300. Control device 300 can calculate the rotational speed and angular speed of motor generators MG1, MG2 based on rotational angles θ1, θ2. The rotation angle sensors 270 and 280 may be omitted by directly calculating the rotation angles θ1 and θ2 from the motor voltage and current in the control device 300.

  Inverter 120 performs bidirectional power conversion between DC power between power supply line HPL and ground line NL1 and AC power input / output to / from motor generators MG1 and MG2. In other words, power supply line HPL corresponds to a “power line” for transmitting power input / output to / from motor generators MG1 and MG2.

  Although not shown, inverter 120 includes a first inverter for driving motor generator MG1 and a second inverter for driving motor generator MG2. Mainly, the first inverter converts AC power generated by motor generator MG1 by the output of engine 220 into DC power in accordance with control signal PWI from control device 300, and supplies the DC power to power supply line HPL and ground line NL1. At this time, converter 110 is controlled by control device 300 so as to operate as a step-down circuit. Thus, power storage device 100 and / or power storage device 150 can be actively charged by the output of engine 220 even while the vehicle is traveling.

  In addition, when starting engine 220, first inverter converts DC power from power storage device 100 and power storage device 150 into AC power in accordance with control signal PWI from control device 300, and supplies the AC power to motor generator MG1. . Thus, engine 220 can be started using motor generator MG1 as a starter.

  The second inverter converts DC power supplied via power supply line HPL and ground line NL1 into AC power in accordance with control signal PWI from control device 300, and supplies the AC power to motor generator MG2. Thereby, motor generator MG2 generates the driving force of electric vehicle 5.

  On the other hand, at the time of regenerative braking of electric vehicle 5, motor generator MG2 generates AC power as drive wheel 260 is decelerated. At this time, the second inverter converts AC power generated by motor generator MG2 into DC power according to control signal PWI from control device 300, and supplies the DC power to power supply line HPL and ground line NL1. As a result, power storage device 100 and / or power storage device 150 are charged during deceleration or downhill travel.

  Power supply system 20 includes power storage device 100 corresponding to “first power storage device”, power storage device 150 corresponding to “second power storage device”, system main relay 190, DC / DC converter 130, and relay RL1. , R2, converter 110, and smoothing capacitors C1, C2.

  The power storage devices 100 and 150 are rechargeable power storage elements, and typically, secondary batteries such as lithium ion batteries and nickel metal hydride batteries are applied. Therefore, hereinafter, power storage device 100 and power storage device 150 are also referred to as battery 100 and battery 150, respectively. However, power storage devices 100 and 150 may be configured by a power storage element other than a battery, such as an electric double layer capacitor, or a combination of a power storage element other than a battery and a battery.

  In addition, power storage devices 100 and 150 may be configured by the same type of power storage device or may be configured by different types of power storage devices.

  Each of the batteries 100 and 150 includes a plurality of battery cells connected in series. That is, the rated value of the output voltage of each of batteries 100 and 150 depends on the number of battery cells connected in series.

  Battery 150 is provided with a voltage sensor 155 for detecting battery voltage VB2. The value detected by voltage sensor 155 is transmitted to control device 300.

  System main relay 190 includes relays SMR1 to SMR3 and a resistor R1. Relays SMR1 and SMR3 are inserted in power supply line PL1 and ground line NL1, respectively. Relay SMR2 is connected in parallel with relay SMR1 and in series with resistor R1. That is, a circuit in which relay SMR2 and resistor R1 are connected in series is connected in parallel to relay SMR1. Relays SMR1 to SMR3 are controlled to be turned on (closed) / off (opened) in accordance with relay control signals SE1 to SE3 given from control device 300.

  DC / DC converter 130 is connected in parallel with converter 110 between power storage device 100 and converter 110. The DC / DC converter 130 steps down the direct current voltage. The electric power output from the DC / DC converter 130 is charged in an auxiliary battery (not shown). The electric power charged in the auxiliary battery is supplied to an auxiliary load such as an electric compressor of the air conditioner and the control device 300.

  Relay RL <b> 1 is connected between power supply line HPL and the positive terminal of power storage device 150. Relay RL2 is connected between the negative terminal of power storage device 150 and ground line NL1. Relays RL1 and RL2 are controlled to be turned on (closed) / off (opened) in accordance with relay control signals SR1 and SR2 provided from control device 300. Relay RL1 is used as a representative example of a “first switch” that can cut off electrical connection between power storage device 150 and power supply line HPL. Relay RL2 is used as a representative example of a “second switch” that can cut off electrical connection between power storage device 150 and ground line NL1. That is, any type of switch can be applied in place of the relays RL1 and RL2.

  Converter 110 is configured to perform bidirectional DC voltage conversion between power storage device 100 and power supply line HPL that transmits the DC link voltage of inverter 120. That is, the input / output voltage of power storage device 100 and the DC voltage between power supply line HPL and ground line NL1 are boosted or lowered in both directions.

  Specifically, converter 110 includes a reactor L1 having one end connected to power supply line PL1, switching elements Q1, Q2 connected in series between power supply line HPL and ground line NL1, and switching elements Q1, Q2. Includes diodes D1 and D2 connected in parallel. As the switching element, an IGBT (Insulated Gate Bipolar Transistor), a bipolar transistor, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or a GTO (Gate Turn Off Thyristor) is typically used. In the present embodiment, a case where an IGBT is used as a switching element will be described as an example.

  Reactor L1 has the other end connected to the emitter of switching element Q1 and the collector of switching element Q2. The cathode of diode D1 is connected to the collector of switching element Q1, and the anode of diode D1 is connected to the emitter of switching element Q1. The cathode of diode D2 is connected to the collector of switching element Q2, and the anode of diode D2 is connected to the emitter of switching element Q2.

  Switching elements Q1, Q2 are controlled to be turned on or off by a control signal PWC from control device 300.

  Smoothing capacitor C1 is connected between power supply line PL1 and ground line NL1, and reduces voltage fluctuation between power supply line PL1 and ground line NL1. The voltage sensor 170 detects the voltage VL between the terminals of the smoothing capacitor C1 and outputs it to the control device 300. Converter 110 boosts the voltage across terminals of smoothing capacitor C1.

  Smoothing capacitor C2 is connected between power supply line HPL and ground line NL1, and reduces voltage fluctuation between power supply line HPL and ground line NL1. That is, the smoothing capacitor C2 smoothes the voltage boosted by the converter 110. The voltage sensor 180 detects the terminal voltage VH of the smoothing capacitor C2 and outputs it to the control device 300. Hereinafter, the voltage VH between the terminals of the smoothing capacitor C2 (that is, the DC side voltage of the inverter 120) is also referred to as “system voltage VH”.

  Although not shown, control device 300 includes a CPU (Central Processing Unit), a storage device, and an input / output buffer, and controls converter 110 and inverter 120. Note that these controls are not limited to software processing, and can be constructed and processed by dedicated hardware (electronic circuit).

  Control device 300 receives detection values of motor currents MCRT1 and MCRT2 flowing in motor generators MG1 and MG2 detected by current sensors 230 and 240, respectively. Control device 300 receives detection values of rotation angles θ1 and θ2 of motor generators MG1 and MG2 detected by rotation angle sensors 270 and 280. Control device 300 also receives detection values of voltages VL and VH across smoothing capacitors C1 and C2 detected by voltage sensors 170 and 180. Furthermore, control device 300 receives an ignition signal IG indicating an on / off state of an ignition switch (not shown).

  Control device 300 generates control signal PWC for converter 110 based on voltages VL and VH across smoothing capacitors C1 and C2. Controller 300 causes converter 110 to perform a step-up operation or a step-down operation by driving switching elements Q1 and Q2 of converter 110 by control signal PWC.

  Control device 300 also includes motor currents MCRT1 and MCRT2 flowing in motor generators MG1 and MG2 detected by current sensors 230 and 240, and rotation angles of motor generators MG1 and MG2 detected by rotation angle sensors 270 and 280, respectively. A control signal PWI for driving the inverter 120 is generated based on θ1 and θ2. Control device 300 converts the DC power supplied from converter 110 into AC power for driving motor generators MG1 and MG2 by driving the switching element of inverter 120 by control signal PWI.

  Control device 300 generates relay control signals SE1 to SE3 based on ignition signal IG. Controller 300 controls on / off of relays SMR1 to SMR3 of system main relay 190 by relay control signals SE1 to SE3. Specifically, when the ignition signal IG is switched from the off state to the on state by the driver turning on the ignition switch, the control device 300 first turns on the relays SMR2 and SMR3 while keeping the relay SMR1 in the off state. To do. At this time, a part of the current is consumed by the resistor R1, and the current flowing into the smoothing capacitor C1 can be reduced, so that an inrush current to the smoothing capacitor C1 can be prevented. Thereafter, when the precharge of the smoothing capacitor C1 is completed, the relay SMR1 is turned on, and subsequently, the relay SMR2 is turned off.

  Control device 300 generates relay control signals SR1 and SR2 based on the operating states of motor generators MG1 and MG2 and the detection values of the sensors. Control device 300 controls ON / OFF of relays RL1 and RL2 by relay control signals SR1 and SR2.

  Each relay shown in the present embodiment is typically turned on (closed) by connecting the contacts when energized, and turned off by disconnecting the contacts when de-energized. It is composed of an electromagnetic relay that is opened. However, any switch including a semiconductor relay can be applied as long as it can control closing (on) and opening (off).

  Thus, power supply system 20 according to the embodiment of the present invention includes a plurality of power storage devices 100 and 150. Power storage device 150 is directly electrically connected to power supply line HPL without going through converter 110. Therefore, when relays RL1 and RL2 are on, system voltage VH cannot be made higher than battery voltage VB2.

  On the other hand, power storage device 100 is connected to power supply line HPL via converter 110. Therefore, even when battery voltage VB1 is lower than system voltage VH, power can be supplied from power storage device 100 to power supply line HPL, and power storage device 100 can be charged by the power of power supply line HPL.

  For this reason, it is preferable that the rated value of the output voltage of power storage device 100 be lower than the rated value of the output voltage of power storage device 150. Thus, the power storage devices 100 and 150 can be used in parallel even if the number of battery cells connected in series in the power storage device 100 is reduced.

  Next, the relationship between the operating state of motor generators MG1 and MG2 and system voltage VH will be described in detail.

  In order to smoothly drive motor generators MG1 and MG2, it is necessary to appropriately set system voltage VH according to the operating point of motor generators MG1 and MG2, specifically, the rotational speed and torque. First, since the modulation rate of power conversion in the inverter 120 has a certain limit, there is an upper limit torque that can be output with respect to the system voltage VH.

  FIG. 2 is a conceptual diagram showing the relationship between the system voltage and the operable region of the motor generator.

  Referring to FIG. 2, the operable range and operating point of the motor generator are indicated by a combination of the rotational speed and torque. The maximum output line 200 indicates the limit of the operable region when the system voltage VH = Vmax (upper limit voltage). The maximum output line 200 has a portion limited by T × N corresponding to the output power even if the torque T <Tmax (maximum torque) and the rotational speed N <Nmax (maximum rotational speed). As the system voltage VH decreases, the operable area becomes narrower.

  For example, the operating point P1 can be realized with the system voltage VH = Va. From this state, when the electric vehicle 5 is accelerated by the accelerator operation of the user, the required value of the vehicle driving force increases. As a result, the output torque of motor generator MG2 increases, so that the operating point changes to P2. However, the operating point P2 cannot be dealt with unless the system voltage VH is raised to Vb (Vb> Va).

  Based on the relationship between the system voltage VH and the limit line of the operating region shown in FIG. 2, the lower limit value (required minimum voltage VHmin) of the system voltage VH at each operating point (rotation speed, torque) of the motor generators MG1, MG2. ).

  Motor generators MG1 and MG2 generate an induced voltage corresponding to the rotational speed. When this induced voltage becomes higher than system voltage VH, the currents of motor generators MG1 and MG2 cannot be controlled. Therefore, the required minimum voltage VHmin of system voltage VH rises at the time of electric vehicle 5 traveling at a high speed in which motor generators MG1 and MG2 have a high rotational speed.

  From these viewpoints, it is understood that the minimum required voltage VHmin for securing the output according to the operating point can be calculated in advance in correspondence with the operating point of motor generators MG1, MG2.

  FIG. 3 is a flowchart illustrating an example of control processing of the power supply control device according to the embodiment of the present invention. Starting with FIG. 3, the processing of each step in the flowchart shown below is executed by software processing or hardware processing by the control device 300. In addition, a series of control processing according to each of the flowcharts shown below is executed by the control device 300 every predetermined control cycle.

  Referring to FIG. 3, in step S01, control device 300 calculates required minimum voltage VHmin from the operating state of motor generators MG1, MG2 using the above-described required voltage map. Further, control device 300 sets voltage command value VH * in consideration of necessary minimum voltage VHmin. Voltage command value VH * is set to be equal to or higher than necessary minimum voltage VHmin. For example, when there is a voltage at which the loss in power supply system 20 and load 10 is minimum as compared to when VH> VHmin, it is preferable to set voltage command value VH * to the voltage from the viewpoint of fuel efficiency priority. On the other hand, when it is desired to use power storage device 150 positively, voltage command value VH * = VHmin may be set because voltage command value VH * is preferably low.

  Thus, voltage command value VH * can be calculated corresponding to the operating points of motor generators MG1 and MG2 in consideration of the necessary minimum voltage VHmin. Therefore, a map (voltage command value map) for calculating voltage command value VH * in accordance with the operating points of motor generators MG1 and MG2 can be created in advance. The voltage command value map is stored in a memory (not shown) of the control device 300. Thus, in the electric vehicle according to the present embodiment, system voltage VH is variably controlled in order to drive motor generators MG1 and MG2 smoothly and efficiently. That is, the voltage amplitude (pulse voltage amplitude) applied to motor generators MG1 and MG2 is variably controlled in accordance with the operating states (rotation speed and torque) of motor generators MG1 and MG2.

  In step S02, control device 300 reads battery information based on the detection value of voltage sensor 155 shown in FIG. The battery information includes at least the battery voltage VB2.

  In step S03, control device 300 compares battery voltage VB2 with voltage command value VH * set in step S01. When battery voltage VB2 becomes equal to or higher than voltage command value VH * (when YES is determined in step S03), control device 300 proceeds to step S04 and turns on relays RL1 and RL2. Thereby, power storage device 150 is connected to power supply line HPL.

  Converter 110 controls charging / discharging of power storage device 100 so that system voltage VH matches voltage command value VH *. Thereby, charge / discharge with respect to the load 10 can be controlled using the power storage devices 100 and 150 in parallel. When electric vehicle 5 performs regenerative braking in this state, power storage devices 100 and 150 can be charged in parallel.

  On the other hand, when battery voltage VB2 falls below voltage command value VH * (when NO in step S03), control device 300 proceeds to step S05 and turns off relays RL1 and RL2. Thereby, power storage device 150 is disconnected from power supply line HPL. Since voltage command value VH * ≧ VHmin as described above, relays RL1 and RL2 are reliably turned off at least when VB2 <VHmin.

  At this time, charging / discharging with respect to the load 10 is controlled through the converter 110 using only the power storage device 100. In this state, when electric vehicle 5 performs regenerative braking, only power storage device 100 is charged.

  As described above, in the power supply vehicle according to the present embodiment, in the electric control device provided with a plurality of power storage devices 100 and 150, even if the converter is provided only in power storage device 100, it depends on the operating state of motor generators MG1 and MG2. Further, variable control of the system voltage VH can be realized. As a result, it is possible to simply and efficiently configure a power supply system that can extend the travel distance by the outputs of motor generators MG1 and MG2 by the electric power of power storage devices 100 and 150.

  In particular, for a high voltage region of system voltage VH corresponding to vehicle acceleration, etc., power storage device 150 having an output voltage lower than the voltage command value (required minimum voltage) is disconnected from power supply line HPL, and power storage device 100 This can be dealt with by boosting the output voltage by the converter 110. Further, when the output voltage of power storage device 150 is higher than the voltage command value (required minimum voltage) and power storage device 150 can be used, power storage devices 100 and 150 can be used in parallel. As described above, since the electric power can be supplied to the motor generators MG1 and MG2 by effectively using the plurality of power storage devices 100 and 150, the power supply system can be efficiently reduced in size and at low cost. It becomes.

  As described above, in power supply system 20 according to the embodiment of the present invention, the first mode in which power storage device 150 is used and the second mode in which power storage device 150 is not used are selected. When switching from the second mode to the first mode, power storage device 150 is connected to power supply line HPL and ground line NL1 by turning on relays RL1 and RL2.

  Note that the relay RL <b> 2 can be omitted by electrically connecting the negative electrode terminal of the power storage device 150 to the negative electrode terminal of the power storage device 100. If it does in this way, size reduction and cost reduction will be attained by reduction of the number of relays. On the other hand, when relay RL2 is arranged as shown in FIG. 1, power storage device 150 can be completely electrically disconnected from power supply system 20, so that a safe configuration can be obtained.

  Here, when voltage difference ΔV (ΔV = VB2−VH) between system voltage VH and battery voltage VB2 is large, power storage device 150 (or smoothing) is established when power storage device 150 is connected to power supply line HPL and ground line NL1. A large inrush current may flow into the capacitor C2). In the relays RL1 and RL2, there is a possibility that the contacts are welded due to an arc generated by the inrush current.

  In order to suppress the inrush current from flowing to the power storage device 150 (or the smoothing capacitor C2), in the same way as the configuration of the system main relay 190 described above, a precharge is performed in parallel with one of the relays RL1 and RL2. It is possible to connect a circuit in which a relay for use and a limiting resistor are connected in series. In such a configuration, ON / OFF of the relays RL1, RL2 and the precharge relay is first controlled so that the relay RL2 and the precharge relay are turned on while the relay RL1 is in the OFF state. As a result, a part of the current is consumed by the limiting resistor, and the current flowing into the power storage device 150 (or smoothing capacitor C2) can be reduced. it can. Thereafter, when the precharge of the smoothing capacitor C2 is completed, the relay RL1 is turned on, and subsequently, the precharge relay is turned off.

  However, in power supply system 20 according to the present embodiment, inrush current to power storage device 150 (or smoothing capacitor C2) may be limited with such a configuration using a circuit including a precharge relay and a limiting resistor. Have difficulty. In power supply system 20, in addition to system voltage VH dynamically changing by variable control by converter 110, output voltage VB2 of power storage device 150 having a higher output voltage rated value than power storage device 100 also dynamically changes. This is because a change in voltage difference ΔV between system voltage VH and battery voltage VB2 cannot be sufficiently handled by a precharge relay and a precharge process using a limiting resistor.

  Therefore, in the embodiment of the present invention, connection of power storage device 150 and power supply line HPL is performed by controlling system voltage VH as follows using converter 110 in association with on / off control of relays RL1 and RL2. Prevent inrush current at the time.

  FIG. 4 is a timing chart for illustrating control processing of relays RL1 and RL2 and converter 110 in control device 300.

  Referring to FIG. 4, it is assumed that the second mode in which power storage device 150 is not used is selected at time t0. At this time t0, the relays RL1 and RL2 are turned off.

  Here, when the first mode using power storage device 150 is selected, first, at time t1, control device 300 turns on only relay RL2 while keeping relay RL1 off. Thus, the potential of the ground line NL1 is stabilized by first connecting the negative electrode terminal of the power storage device 150 and the ground line NL1.

  Next, control device 300 compares system voltage VH detected by voltage sensor 180 with battery voltage VB2 detected by voltage sensor 155. When system voltage VH is outside the predetermined allowable range, control device 300 controls the voltage conversion operation of converter 110 such that system voltage VH falls within the allowable range.

  The allowable range of system voltage VH is set according to battery voltage VB2 from voltage sensor 155. In FIG. 4, the allowable range is set so as to have a predetermined threshold value ΔVth with respect to battery voltage VB2. This threshold value ΔVth is set in consideration of the allowable current of relays RL1 and RL2 so that the contacts of relays RL1 and RL2 are not welded.

  When the system voltage VH converges within the allowable range by the voltage conversion operation of the converter 110 (time t2), the control device 300 turns on the relay RL1. Thereby, power storage device 150 is connected to power supply line HPL.

  FIG. 5 is a diagram illustrating a configuration example of a control block for realizing control of relays RL <b> 1 and RL <b> 2 and converter 110 in control device 300.

  Referring to FIG. 5, control device 300 includes a voltage command generation unit 310, a subtraction unit 320, a PI control unit 330, a transfer function 340, and a relay control unit 350.

  Voltage command generation unit 310 sets voltage command value VH * based on the operating state of motor generators MG1, MG2. As described in FIG. 2, voltage command generation unit 310 calculates required minimum voltage VHmin from the operating state of motor generators MG1 and MG2, and sets voltage command value VH * in consideration of the calculated minimum required voltage VHmin. To do.

  When voltage command value VH * is set, voltage command generation unit 310 executes the control process shown in the flowchart of FIG. 3, thereby depending on the comparison result between voltage command value VH * and battery voltage VB2. One of the first mode using 150 and the second mode not using power storage device 150 is selected. Then, voltage command generation unit 310 outputs information regarding the selected mode to relay control unit 350.

  When the second mode is selected, voltage command generation unit 310 sets battery voltage VB2 detected by voltage sensor 155 to voltage command value VH *.

  Subtraction unit 320 calculates voltage deviation ΔVH from the difference between voltage command value VH * and system voltage VH, and outputs the result to PI control unit 330. PI control unit 330 generates a PI output corresponding to voltage deviation ΔVH according to a predetermined proportional gain and integral gain, and outputs the PI output to transfer function 340. The PI control unit 330 constitutes a voltage feedback control element.

  Specifically, PI control unit 330 includes a proportional element, an integral element, and an adder. The proportional element multiplies the voltage deviation ΔVH by a predetermined proportional gain Kp and outputs the result to the adder, and the integral element integrates the voltage deviation ΔVH with a predetermined integral gain Ki (integration time: 1 / Ki) to the adder. Output. The adder adds the outputs from the proportional element and the integral element to generate a PI output. This PI output corresponds to a feedback control amount for realizing voltage control. The PI control unit 330 generates a duty ratio command value d for voltage control according to the sum of the feedback control amount and the feedforward control amount DvFF. Duty ratio command value d is a control command that defines the on-duty of switching element Q2 (FIG. 1) of converter 110 in voltage control. Further, feedforward control amount DvFF in voltage control is set according to a voltage difference between voltage command value VH * and voltage VB <b> 1 of power storage device 100. Transfer function 340 corresponds to the transfer function of converter 110 for power storage device 100 operating as a voltage source.

  Relay control unit 350 controls ON / OFF of relays RL <b> 1 and RL <b> 2 according to mode information given from voltage command generation unit 310. When the second mode is selected, relay control unit 350 turns off relays RL1 and RL2 by relay control signals SR1 and SR2. At the time of switching from the second mode to the first mode, relay control unit 350 first turns on relay RL2 by relay control signal SR2, and connects the negative terminal of power storage device 150 to ground line NL1. Then, relay control unit 350 compares system voltage VH with battery voltage VB2. When it is determined that system voltage VH has converged within the allowable range (VB2 ± ΔVth), relay control unit 350 turns on relay RL1 by relay control signal SR1. Thereby, the positive terminal of power storage device 150 is connected to power supply line HPL.

  FIG. 6 is a flowchart showing a control processing procedure for realizing control of relays RL 1, RL 2 and converter 110 in control device 300. The process of the flowchart of FIG. 6 is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  Referring to FIG. 6, control device 300 determines in step S01 whether or not the first mode using power storage device 150 is selected. If the first mode has not been selected (NO in step S01), the process returns to the beginning.

  On the other hand, when the first mode is selected (when YES is determined in step S01), control device 300 subsequently determines whether relays RL1 and RL2 are turned on in step S02. If relays RL1 and RL2 are turned on (YES in step S02), the process is returned to the beginning.

  On the other hand, when relays RL1 and RL2 are turned off (when NO is determined in step S02), control device 300 keeps relay RL1 turned off by relay control signals SR1 and SR2 in step S03. Only relay RL2 is turned on.

  Subsequently, control device 300 sets voltage command value VH * based on battery voltage VB2 from voltage sensor 155 and sets an allowable range (VB2 ± ΔVth) of system voltage VH. Then, converter 110 is controlled so that system voltage VH matches voltage command value VH *.

  Specifically, in step S04, control device 300 determines whether or not system voltage VH is higher than the upper limit value (VB2 + ΔVth) of the allowable range. When system voltage VH is higher than the upper limit value (VB2 + ΔVth) (when YES is determined in step S04), control device 300 controls converter 110 to decrease system voltage VH in step S05.

  On the other hand, if system voltage VH is equal to or lower than the upper limit value (VB2 + ΔVth) (NO determination in step S04), then, in step S06, is system voltage VH lower than the lower limit value (VB2−ΔVth) of the allowable range? Determine whether or not. When system voltage VH is lower than the lower limit value (VB2−ΔVth) (when YES in step S06), control device 300 controls converter 110 to increase system voltage VH in step S07.

  On the other hand, when system voltage VH is equal to or higher than the lower limit value (VB2-ΔVth) (NO determination in step S07), control device 300 determines that system voltage VH has converged within an allowable range. In step S08, the relay RL1 is turned on.

  As described above, in the embodiment of the present invention, in power supply system in which power storage device 150 is provided on the output side of a converter capable of boosting the output voltage of power storage device 100, power storage device 150 is connected to power supply line HPL and ground line NL1. First, relay RL2 on the negative electrode side of power storage device 150 is turned on, and after the voltage difference between the output voltage of power storage device 150 and the voltage of the power line is reduced by DC voltage conversion of converter 110, power storage device 150 The relay RL1 on the positive electrode side is turned on. Thus, an inrush current at the time of connection between power storage device 150 and the power line and the ground line can be prevented without using a precharge relay and a limiting resistor. As a result, the welding of the relay due to the inrush current can be avoided.

  The configuration of the load 10 (that is, the drive system) of the electric vehicle 5 shown in FIG. 1 is not limited to the illustrated configuration. That is, the present invention can be applied in common to electric vehicles equipped with a traveling motor such as an electric vehicle and a fuel cell vehicle. Furthermore, the load 10 is not limited to a drive system that generates a driving force of the vehicle, and it is described in a confirming manner that the load 10 can be applied to an apparatus that consumes power.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  5 Electric vehicle, 10 load, 20 power supply system, 100, 150 power storage device, 110 converter, 120 inverter, 130 DC / DC converter, 170, 180 voltage sensor, 190 system main relay, 220 engine, 230, 240 current sensor, 250 Power split mechanism, 260 drive wheels, 270, 280 rotation angle sensor, 300 controller, 310 voltage command generator, 320 subtractor, 330 PI controller, 340 transfer function, 350 relay controller, C1, C2 smoothing capacitor, MG1 , MG2 motor generator, SMR1-SMR3, RL1, R2 relay.

Claims (5)

A power supply control device for an electric vehicle equipped with an electric motor for generating vehicle driving force,
A first power storage device;
A second power storage device;
A power line for transmitting power to and from the motor;
A converter for performing bidirectional DC voltage conversion between the first power storage device and the power line;
A first switch connected between the second power storage device and the power line;
A second switch connected between the second power storage device and a ground line;
A control device for controlling on / off of the first and second switches according to an operating state of the electric motor,
When the control device turns on the second switch, after the DC voltage conversion of the converter reduces the deviation of the voltage of the power line with respect to the output voltage of the second power storage device to a predetermined threshold value A power supply control device for an electric vehicle that turns on the first switch. The controller is
Setting means for setting a voltage command value of the power line according to an operating state of the electric motor;
2. The electric motor according to claim 1, further comprising: an opening / closing control unit that controls on / off of the first and second switches according to a comparison result between an output voltage of the second power storage device and the voltage command value. Vehicle power supply control device. The setting means calculates a necessary minimum voltage of the power line according to an operating state of the electric motor, sets the voltage command value in a range equal to or more than the necessary minimum voltage,
The switching control means turns on the first and second switches when the output voltage of the second power storage device is equal to or higher than the voltage command value, while the output voltage of the second power storage device is The power supply control device for an electric vehicle according to claim 2, wherein when the voltage command value is lower than the voltage command value, the first and second switches are turned off. The controller is
Voltage conversion control means for controlling DC voltage conversion of the converter so that the voltage of the power line is within an allowable range defined by the output voltage of the second power storage device and the predetermined threshold value. ,
The power source for the electric vehicle according to claim 2, wherein the opening / closing control means turns on the first and second switches when the voltage of the power line falls within the allowable range by the voltage conversion control means. Control device.   The power supply control device for an electric vehicle according to any one of claims 1 to 4, wherein a rated value of an output voltage of the first power storage device is lower than a rated value of an output voltage of the second power storage device.

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