JP2011223719A - Power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle power supply apparatus for reducing cost and avoiding performance degradation.SOLUTION: A control device 15 includes an allowable discharge power calculating section 154 for calculating a battery allowable discharge power so as to prevent a battery voltage from being reduced to a managed lower-limit voltage or less and a HV controlling section 150 for outputting a drive power instruction value so as to prevent a motor power consumption corresponding to the drive power instruction value from exceeding the allowable discharge power. The managed lower-limit voltage is a voltage as a lower-limit voltage allowable for a battery or more, and is set to the battery voltage at which a voltage converter can maintain a fixed voltage output or more.

Description

  The present invention relates to a power supply device, and more particularly to a power supply device that supplies power to a drive motor of a vehicle.

  Recently, as an environmentally-friendly vehicle, a hybrid vehicle (electric vehicle) incorporating an electric motor (motor) in a drive device and an electric vehicle have attracted a great deal of attention, and some of them have been put into practical use. This hybrid vehicle includes a secondary battery, an electric double layer capacitor, etc. to supply power to the motor that is the driving source, or to convert kinetic energy into electrical energy and store it during regenerative braking. Is installed. The discharge from the power supply or the charge to the power supply is performed in consideration of the remaining capacity (SOC: State of Charge) of the power supply, for example. By maintaining the SOC within an appropriate range, overcharge and overdischarge of the power source can be suppressed.

  In hybrid vehicles and electric vehicles, as a substitute for an alternator that generates power by being rotated by an engine, a high-voltage battery is used as a power source to step down a DC / DC converter to charge an auxiliary battery or supply power to an auxiliary load. Is taken.

  Japanese Patent Laid-Open No. 2009-213223 (Patent Document 1) discloses that when the limiter of the DC / DC converter is operated when the load current is increased, the output characteristic of the DC / DC converter is abruptly increased even when the output current is increased. Instead of dropping, the voltage is dropped to limit the power to a certain value. The target value to be lowered is the voltage of the auxiliary battery. When the DC / DC converter is operating so as to output the voltage of the auxiliary battery, the auxiliary battery cannot be charged, but it can be said that the current of the auxiliary battery is not continuously consumed. Therefore, the auxiliary battery can be prevented from being over-discharged even if the vehicle continues to travel, so that no problem occurs when the vehicle is traveling.

  By introducing the control for limiting the power to a constant value in this way, it is possible to prevent a sudden voltage change. Therefore, it is possible to make it difficult for the driver to feel a change in the behavior of the load such as flickering of the headlight, and to reduce discomfort.

JP 2009-213223 A JP 2008-312400 A JP 2009-087720 A JP 2009-166513 A JP 2009-184476 A

  In recent years, there is an increasing demand for cost reduction in order to promote the spread of hybrid vehicles and electric vehicles. In particular, the proportion of the high-voltage battery that supplies power to the drive motor occupies the entire vehicle cost is high, and there is a great demand for cost reduction of the battery.

  In the battery, a plurality of battery cells are connected in series to achieve a high voltage. However, if the number of battery cells is reduced, a significant cost reduction can be achieved. From this viewpoint, optimization of the number of battery cells is important.

  On the other hand, some devices are designed to match the current battery voltage. For example, a DC / DC converter that supplies power to an auxiliary battery or an auxiliary load is such a device. Changing the design of such a device by changing the number of battery cells is undesirable in terms of device sharing.

  An object of the present invention is to provide a power supply device for a vehicle in which a reduction in performance is avoided while reducing costs.

  In summary, the present invention is a power supply device for driving a high-voltage motor for driving a vehicle and supplying power to a low-voltage auxiliary load, and the high-voltage power supply and power supply from the power supply. A motor driving device that drives the motor according to the driving force command value, a voltage converter that receives the first power supply voltage from the power source and outputs the second power supply voltage to the auxiliary load, and a driving force command value. And a control device for generation. The control device includes a discharge allowable power calculation unit that calculates the discharge allowable power of the power supply so that the first power supply voltage that is the voltage of the power supply does not fall below the management lower limit voltage, and the power consumption of the motor corresponding to the driving force command value is And a control unit that outputs a driving force command value so as not to exceed the discharge allowable power. The management lower limit voltage is equal to or higher than the lower limit voltage allowed for the power supply, and is set to be equal to or higher than the power supply voltage at which the voltage converter can maintain the output of the second power supply voltage.

  Preferably, the control device further includes a slip detection unit that detects a slip of the wheel driven by the motor, and a management lower limit voltage setting unit that sets a management lower limit voltage in the discharge allowable power calculation unit. The management lower limit voltage setting unit sets the management lower limit voltage to the first voltage value when no slip is detected by the slip detection unit, and temporarily sets the management lower limit voltage when slip is detected by the slip detection unit. The voltage is set to a second voltage value that is higher than the first voltage value.

  Preferably, the power supply includes a plurality of battery packs connected in series. Each of the plurality of battery packs is provided with a space for accommodating a plurality of battery cells. At least one of the plurality of battery packs includes a part of the plurality of battery cells in order to match the lower limit voltage allowed for the power source to the voltage of the power source that the voltage converter can maintain the output of the second power source voltage. And the number of battery cells connected in series is adjusted. At least one of the plurality of battery packs includes a connection conductor for removing a part of the plurality of battery cells and conducting the part that is in an open state.

  According to the present invention, when the number of battery cells is changed to reduce the cost of the vehicle, the control setting is changed to prevent output fluctuation of the DC / DC converter. Can be used without design changes.

1 is a block diagram illustrating a configuration of a vehicle equipped with a power supply device according to an embodiment of the present invention. It is a block diagram which shows the structure of the power supply device by this invention. It is a block diagram which shows the control structure in the control apparatus 15 according to embodiment of this invention. FIG. 6 is a diagram showing characteristics of a DC / DC converter 146. It is a wave form diagram for demonstrating the fluctuation | variation of the voltage given to auxiliary machinery load. 4 is a flowchart for explaining drive control of a motor generator by a control device 15; It is a wave form diagram for demonstrating the fluctuation | variation of the voltage given to the auxiliary machine load at the time of invention of Embodiment 1 being applied. 6 is a flowchart illustrating drive control of a motor generator by control device 15 executed in a second embodiment. 4 is a diagram for explaining a configuration of a battery 10. FIG. It is the figure which showed the structure of the battery pack in which the number of battery cells was adjusted finely.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
FIG. 1 is a block diagram illustrating a configuration of a vehicle equipped with a power supply device according to an embodiment of the present invention.

  Referring to FIG. 1, a hybrid vehicle 100 according to the present invention includes a battery 10, an ECU (Electronic Control Unit) 15, a PCU (Power Control Unit) 20, a power output device 30, and a differential gear (differential gear). Dynamic gear) 40, front wheels 50L and 50R, rear wheels 60L and 60R, front seats 70L and 70R, and a rear seat 80.

  The battery 10 is a direct current power source and includes a secondary battery such as nickel metal hydride or lithium ion. The battery 10 supplies a DC voltage to the PCU 20 and is charged by the DC voltage from the PCU 20. The battery 10 is disposed, for example, at the rear portion of the rear seat 80 and is electrically connected to the PCU 20. The PCU 20 collectively indicates power converters required in the hybrid vehicle 100.

  Sensor output 17 from various sensors indicating the driving situation / vehicle situation is input to the ECU 15. The sensor output 17 includes the accelerator opening corresponding to the accelerator depression amount detected by the position sensor disposed on the accelerator pedal 35, the wheel speed sensor output, and the like. The ECU 15 comprehensively performs various controls relating to the hybrid vehicle 100 based on these input sensor outputs.

  Power output device 30 is provided as a wheel driving force source, and includes an engine and motor generators MG1 and MG2. These are mechanically connected via a power split mechanism (not shown). Then, according to the traveling state of the hybrid vehicle 100, the driving force is distributed and combined among the three parties via the power split mechanism, and as a result, the front wheels 50L and 50R are driven. The differential gear 40 transmits the power from the power output device 30 to the front wheels 50L and 50R, and transmits the rotational force of the front wheels 50L and 50R to the power output device 30.

  Thus, power output device 30 transmits the power from engine and / or motor generators MG1, MG2 to front wheels 50L, 50R via differential gear 40 to drive front wheels 50L, 50R. In addition, power output device 30 generates power by the rotational force of motor generators MG1 and MG2 by front wheels 50L and 50R, and supplies the generated power to PCU 20.

  Motor generators MG1 and MG2 can function as both a generator and an electric motor, but motor generator MG1 mainly operates as a generator, and motor generator MG2 mainly operates as an electric motor.

  Specifically, motor generator MG1 is used as an electric motor that starts the engine during acceleration. At this time, motor generator MG1 is supplied with electric power from battery 10 and is driven as an electric motor, and cranks and starts the engine.

  Further, after the engine is started, motor generator MG1 is rotated by the driving force of the engine transmitted through the power split mechanism to generate electric power.

  Motor generator MG2 is driven by at least one of the electric power stored in battery 10 and the electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to the driving shafts of front wheels 50L and 50R via differential gear 40. Thereby, motor generator MG2 assists the engine to travel the vehicle, or travels the vehicle only by its own driving force.

  At the time of regenerative braking of the vehicle, motor generator MG2 is driven by front wheels 50L and 50R to operate as a generator. At this time, the regenerative power generated by motor generator MG2 is charged to battery 10 via PCU 20.

  PCU 20 boosts the DC voltage from battery 10 according to a control instruction from ECU 15 during powering operation of motor generators MG1 and MG2, and converts the boosted DC voltage into an AC voltage, and is included in power output device 30. The motor generators MG1 and MG2 to be driven are controlled.

  In addition, during regenerative braking of motor generators MG1 and MG2, PCU 20 charges battery 10 by converting the AC voltage generated by motor generators MG1 and MG2 into a DC voltage in accordance with a control instruction from ECU 15.

  Thus, in hybrid vehicle 100, “power supply device” that drives and controls motor generators MG <b> 1 and MG <b> 2 is configured by battery 10, PCU 20, and a portion of ECU 15 that controls PCU 20.

Next, the configuration of the power supply device according to the present invention will be described.
FIG. 2 is a block diagram showing the configuration of the power supply device according to the present invention.

  Referring to FIG. 2, a power supply device according to the present invention includes a battery 10 in which a plurality of battery cells are connected in series, a voltage sensor 12 that detects a DC voltage Vb from battery 10, and driving motor generators MG1 and MG2. A portion related to control (hereinafter, simply referred to as “PCU 20”) and a portion of the ECU 15 that controls the PCU 20 (hereinafter referred to as “control device 15”) are provided.

  PCU 20 includes a converter 110, a smoothing capacitor 120, motor driving devices 131 and 132 corresponding to motor generators MG1 and MG2, respectively, and a converter / inverter control unit 140. In this embodiment, since motor generators MG1 and MG2 that are AC motors are driven and controlled, motor drive devices 131 and 132 are configured by inverters. Hereinafter, the motor drive devices 131 and 132 are referred to as inverters 131 and 132.

  Based on various sensor outputs 17, control device 15 determines required torque Trq for motor generators MG1 and MG2 in consideration of output distribution with engine ENG and the like. Further, control device 15 calculates optimal motor operating voltage Vm # according to the operating state of motor generators MG1, MG2.

  Control device 15 further performs voltage command value Vmr and motor generator MG1 of motor operating voltage Vm by a method described later based on required torque Trq, optimal motor operating voltage Vm #, and DC voltage Vb from voltage sensor 12. , MG2 generates a torque command value Tref. Voltage command value Vmr and torque command value Tref are applied to converter / inverter control unit 140.

  Converter / inverter control unit 140 generates converter control signal Scnv for controlling the operation of converter 110 in accordance with voltage command value Vmr from control device 15. Further, converter / inverter control unit 140 generates inverter control signals Spwm1 and Spwm2 for controlling the operations of inverters 131 and 132, respectively, according to torque command value Tref from control device 15.

Next, the control structure of the control device 15 according to the present invention will be described with reference to FIG.
FIG. 3 is a block diagram showing a control structure in control device 15 according to the embodiment of the present invention. The control block shown in FIG. 3 is typically realized by the control device 15 executing a program stored in advance, but part or all of the configuration may be realized as dedicated hardware.

  Referring to FIG. 3, control device 15 includes an HV control unit 150, a battery management lower limit voltage setting unit 152, and a discharge allowable power calculation unit 154.

  HV control unit 150 sets travel mode DM of hybrid vehicle 100 and outputs the set travel mode DM to battery management lower limit voltage setting unit 152.

  Specifically, the HV control unit 150 travels by the output of only the motor generator MG2 in accordance with the accelerator opening and the wheel speed included in the various sensor outputs 17 (hereinafter also referred to as “EV travel mode”) and The mode (hereinafter also referred to as “HV travel mode”) is switched according to the output of engine ENG and motor generator MG2.

  For example, at the time of starting and running at a low speed, or at a light load such as when going down a gentle slope, in order to avoid a region where engine efficiency is low, the engine ENG output is not used, and the vehicle travels with the output of only the motor generator MG2. The EV travel mode is set. In other words, in a region where the accelerator opening is small, hybrid vehicle 100 travels using only the output of motor generator MG2. In this case, the operation of engine ENG is stopped except when an engine start request condition described later is satisfied.

  In addition, you may make it set to EV driving mode according to operation of the EV driving | running | working selection switch (not shown) by a driver | operator.

  On the other hand, during normal travel where the accelerator opening is larger than the predetermined value α%, the engine ENG is started and set to the HV travel mode. Thereby, the output from engine ENG is divided into the driving force of front wheels 50L and 50R and the driving force for power generation by motor generator MG1 by the power split mechanism. Electric power generated by motor generator MG2 is used to drive motor generator MG2. Therefore, during normal travel, front wheels 50L and 50R are driven by the output from engine ENG and the output from motor generator MG2. At this time, the control device 15 controls the power split ratio by the power split mechanism so that the overall efficiency is maximized.

  Further, at the time of high acceleration, the electric power supplied from battery 10 is further used for driving motor generator MG2, and the driving force of front wheels 50L and 50R further increases.

  During regenerative braking, motor generator MG2 is driven to rotate by front wheels 50L and 50R to generate electric power. The electric power recovered by the regenerative power generation of motor generator MG2 is converted into a DC voltage by PCU 20 and used for charging battery 10. Further, when the vehicle is stopped, the engine ENG is automatically stopped.

  Thus, in hybrid vehicle 100, the operation of engine ENG and motor generator MG2 is controlled by the combination of the output from engine ENG and the output from motor generator MG2 using electric energy as a source, that is, according to the vehicle situation. The vehicle is driven with improved fuel efficiency.

  At this time, in a region where the accelerator opening is small, engine ENG start control is performed when an engine start request condition that requires engine ENG start is satisfied. The engine start request condition includes a case where a driving force request such as high acceleration is given from the driver. As an example, it includes that the accelerator opening exceeds a predetermined value α%. Furthermore, a case may be included in which a request unrelated to the driving force request is given, such as when the battery output needs to be charged, or when the engine ENG is warming up.

  HV control unit 150 cranks and starts engine ENG by driving motor generator MG1 as an electric motor upon receiving power supplied from battery 10 as engine start control when the engine start request condition is satisfied. . Further, HV control unit 150 generates an H (logic high) level engine start request signal and outputs the signal to battery management lower limit voltage setting unit 152.

  Specifically, the battery management lower limit voltage setting unit 152 normally sets the management lower limit voltage Vb_lim to a predetermined voltage VI1. The predetermined voltage VI1 is set in advance based on the charge / discharge characteristics of the battery 10 and the like so that the SOC of the battery 10 is not within an appropriate range and is not overdischarged.

  Discharge allowable power calculation unit 154 receives management lower limit voltage Vb_lim from battery management lower limit voltage setting unit 152 and receives DC voltage Vb from voltage sensor 12, so that discharge allowable power does not fall below control lower limit voltage Vb_lim. Wout is derived.

  Specifically, the discharge allowable power calculation unit 154 compares the magnitude relationship between the DC voltage Vb from the voltage sensor 12 and the management lower limit voltage Vb_lim, and when the DC voltage Vb is higher than the management lower limit voltage Vb_lim, Discharge allowable power Wout is derived based on voltage Vb. At this time, discharge allowable power calculation unit 154 derives discharge allowable power Wout based on the SOC calculated from DC voltage Vb using a known technique. Note that the discharge allowable power Wout at this time is a limit value of the discharge power at each time point defined by the chemical reaction limit of the battery 10.

  In actuality, discharge allowable power calculation unit 154 stores a discharge allowable power map defined in advance using DC voltage Vb as a parameter, and derives discharge allowable power Wout at each time point based on DC voltage Vb.

  On the other hand, when the DC voltage Vb becomes equal to or lower than the management lower limit voltage Vb_lim, the discharge allowable power calculation unit 154 fixes the discharge allowable power Wout to a predetermined minimum allowable power (lower limit power). In this way, power limitation of the battery 10 is performed so that the DC voltage Vb does not fall below the management lower limit voltage Vb_lim.

  As described above, the HV control unit 150 sets the travel mode DM of the hybrid vehicle 100 in accordance with the various sensor outputs 17, and based on the various sensor outputs 17, the motor generator MG <b> 1 takes into account output distribution with the engine and the like. MG2 required torque Trq is determined. Furthermore, the HV control unit 150 calculates an optimum motor operating voltage Vm # according to the determined required torque Trq and the motor rotational speed.

  Then, HV control unit 150 determines voltage command value Vmr for motor operating voltage Vm and torque command value Tref for motor generators MG1 and MG2 based on required torque Trq, optimum motor operating voltage Vm #, and discharge allowable power Wout. Is generated.

  Specifically, the HV control unit 150 calculates motor power consumption corresponding to the required torque Trq, and determines whether or not the calculated motor power consumption exceeds the discharge allowable power Wout. At this time, if the calculated motor consumption power is equal to or less than the discharge allowable power Wout, even if power is consumed by the motor generators MG1, MG2 according to the required torque Trq, the discharge allowable power Wout is not exceeded. The HV control unit 150 sets the torque command value Tref to be equal to the required torque Trq. Further, the HV control unit 150 sets the voltage command value Vmr to be equal to the optimum motor operating voltage Vm #.

  On the other hand, when the motor power consumption exceeds the discharge allowable power Wout, if the motor generators MG1 and MG2 consume power according to the required torque Trq, the motor power consumption exceeds the discharge allowable power Wout. Therefore, in this case, the motor power consumption is limited so as not to exceed the discharge allowable power Wout.

  Specifically, the motor power consumption at the limit where motor power consumption = discharge allowable power Wout is established, and the torque command value Tref is calculated in correspondence with the calculated motor power consumption. That is, the torque command value Tref is limited to be smaller than the initial required torque Trq. Similarly, voltage command value Vmr is limited to be smaller than the initial optimum motor operating voltage Vm # in accordance with the limited required torque Trq.

  Torque command value Tref and voltage command value Vmr generated in this way are applied to converter / inverter control unit 140. Converter / inverter control unit 140 determines the boost ratio in converter 110 (FIG. 2) based on voltage command value Vmr, and generates converter control signal Scnv so that this boost ratio is realized.

  Further, converter / inverter control unit 140 causes inverter control signals in accordance with output values from various sensors so that motor currents that generate torque according to torque command value Tref flow in motor generators MG1 and MG2. Spwm1 and Spwm2 are generated. For example, inverter control signals Spwm1 and Spwm2 are PWM signal waves generated according to a general control method. The output values from the various sensors include, for example, output values from the position sensors and speed sensors of the motor generators MG1 and MG2, output values from the current sensors that detect each phase current, and voltages that detect the motor operating voltage Vm. The output value from the sensor is included.

  2 and 3, the power supply device for driving the motor for driving the vehicle receives the battery 10 and the power supplied from the battery 10 and drives the motor according to the driving force command value. Drive devices 131 and 132, DC / DC converter 146 that receives power supply voltage Vb from battery 10 and outputs power supply voltage Vdcout to the auxiliary load, and control device 15 that generates a drive force command value are provided. The control device 15 includes a discharge allowable power calculation unit 154 that calculates discharge allowable power of the battery 10 so that the first power supply voltage, which is the voltage of the battery 10, does not fall below the management lower limit voltage, and a motor corresponding to the driving force command value. The HV control unit 150 that outputs a driving force command value is included so that the power consumption does not exceed the allowable discharge power. The management lower limit voltage is equal to or higher than the lower limit voltage allowed for the battery 10 and is set to be equal to or higher than the voltage of the battery 10 at which the voltage converter can maintain the output of the second power supply voltage. The lower limit voltage allowed for battery 10 is equal to or lower than the voltage of battery 10 at which the voltage converter can maintain the output of power supply voltage Vdcout constant.

FIG. 4 is a diagram showing the characteristics of the DC / DC converter 146.
Referring to FIG. 4, DC / DC converter 146 outputs a constant voltage VO1 (for example, 15V) if the input voltage (voltage Vb of battery 10) is equal to or greater than VI1 (for example, 195V).

  Although not shown, the DC / DC converter 146 receives the voltage of the battery 10 and generates an AC waveform, an insulating transformer that transforms the generated AC, and rectifies and smoothes the AC that has been transformed by the insulating transformer. And a DC output unit for outputting a DC voltage. Basically, the lower limit voltage at which a constant voltage VO1 can be maintained is determined by the transformation ratio of the insulating transformer.

  In the range where the input voltage is lower than VI1, the input voltage and the output voltage are in a substantially proportional relationship. In the range where the input voltage is higher than VI1, the output voltage is maintained at a constant value VO1 (for example, 15V) by changing the duty ratio of the AC waveform or intermittently stopping the generation of the AC waveform.

  When DC / DC converter 146 has such characteristics, if the voltage of battery 10 fluctuates including a range lower than VI1 (for example, 195 V), the voltage applied to auxiliary load 148 will fluctuate accordingly. .

FIG. 5 is a waveform diagram for explaining fluctuations in voltage applied to the auxiliary machine load.
Referring to FIG. 5, the input voltage (battery voltage Vb) and the output voltage (Vdcout) are shown. Here, consider reducing the number of cells of the battery 10 for cost reduction. For example, if the number of battery cells in the battery pack is 12, and the allowable lower limit voltage per cell is 1V, the voltage of one battery pack is 12V. The total voltage of the 17 battery packs (the lower limit voltage allowed for the battery 10) is 204V. Here, if the number of battery packs is reduced to 16 for cost reduction, the lower limit voltage allowed for the battery 10 is 12V × 16 = 192V. And control device 15 shall restrict PCU20 by using the same 192V as management lower limit voltage Vb_lim so that battery voltage Vb may not fall below 192V.

  However, in this case, the input voltage to the DC / DC converter 146 is lower than the voltage (195 V) at which the DC / DC converter 146 can output a constant value (for example, 15 V). Then, the battery voltage Vb repeats the change as shown in FIG.

  Since the auxiliary battery 147 is also connected to the auxiliary load 148, the temporary output decrease is clamped by the voltage (for example, 12V) of the auxiliary battery 147 (t2 to t3). However, if the power consumption of the PCU 20 fluctuates in a portion close to overload, the voltage of the battery 10 may fluctuate including a range lower than VI1 (for example, 195 V). It fluctuates between (t4 to t5) and 12V (t2 to t3) and may blink repeatedly.

  FIG. 6 is a flowchart for explaining drive control of the motor generator by the control device 15. 6 is realized by the control device 15 (FIG. 2) functioning as each control block shown in FIG.

  3 and 6, battery management lower limit voltage setting unit 152 sets management lower limit voltage Vb_lim of battery 10 to voltage VI1 (for example, 195 V) (step S10).

  The control lower limit voltage Vb_lim is a voltage equal to or higher than the lower limit voltage (for example, 192 V) allowed for the battery 10 and the voltage of the battery 10 (for example, the DC / DC converter 146 can maintain its output at a constant value (for example, 15 V)). In FIG. 4, it is set to 195 V) or more.

  Further, the lower limit voltage (for example, 192 V) allowed for battery 10 is equal to or lower than the voltage of battery 10 (for example, 195 V in FIG. 4) at which DC / DC converter 146 can maintain a constant value output (for example, 15 V). .

  The control lower limit voltage Vb_lim set in step S10 is output to the discharge allowable power calculation unit 154.

  When allowable discharge power calculation unit 154 receives management lower limit voltage Vb_lim from battery management lower limit voltage setting unit 152 and receives DC voltage Vb from voltage sensor 12 (FIG. 2), whether or not DC voltage Vb falls below management lower limit voltage Vb_lim. Is determined (step S20).

  When DC voltage Vb is equal to or higher than control lower limit voltage Vb_lim (NO in step S20), discharge allowable power calculation unit 154 refers to the discharge allowable power map, and discharge allowable power Wout according to DC voltage Vb. Is calculated (step S40).

  On the other hand, when DC voltage Vb is lower than management lower limit voltage Vb_lim (YES in step S20), discharge allowable power calculation unit 154 fixes discharge allowable power Wout to a preset lower limit power. Thus, the output power from the battery 10 is limited (step S30).

  Based on the discharge allowable power Wout calculated and set in step S30 or S40 and the required torque Trq calculated according to various sensor outputs, the HV control unit 150 determines that the motor power consumption corresponding to the required torque Trq is the discharge allowable power. A torque command value Tref is calculated so as not to exceed Wout (step S50).

  Thus, switching control of inverters 131 and 132 is performed in accordance with torque command value Tref calculated in step S50, and torque (ie, motor current) of motor generators MG1 and MG2 is controlled (step S60).

  FIG. 7 is a waveform diagram for explaining fluctuations in the voltage applied to the auxiliary load when the invention of the first embodiment is applied.

  Referring to FIG. 7, the input voltage (battery voltage Vb) and the output voltage (Vdcout) are shown. Consider reducing the number of cells of the battery 10 for cost reduction. It is assumed that the lower limit voltage allowed for the battery 10 determined from the reduced number of battery cells is 192V. Then, the control device 15 limits the PCU 20 with the slightly lower 195V as the management lower limit voltage Vb_lim so that the battery voltage Vb does not fall below 192V.

  Since the DC / DC converter 146 has the characteristics shown in FIG. 4, even if the input voltage is 195V, it can output 15V. Therefore, as shown in FIG. 7, even if the battery voltage Vb fluctuates, the output Vdcout of the DC / DC converter 146 can continue to output a constant voltage of 15V.

  As described above, according to the embodiment of the present invention, the management lower limit voltage Vb_lim is set to a voltage (for example, 195 V) slightly higher than the lower limit voltage (for example, 192 V) allowed for the battery 10 determined by the number of cells of the battery 10. . As a result, the DC / DC converter 146 can maintain a constant voltage (for example, 15V) output, so that fluctuations in the behavior of the auxiliary machine load (for example, repeated blinking of lighting) become inconspicuous, and the auxiliary battery rise is suppressed. Can be.

  That is, when considering reducing the number of cells of the battery 10 as much as possible for cost reduction, the DC / DC converter 146 can maintain a constant voltage output with the lower limit voltage allowed for the battery 10. The case where it becomes lower than a voltage is considered. In such a case, the control lower limit voltage Vb_lim is set to be equal to or higher than a voltage at which the DC / DC converter 146 can maintain a constant voltage output, so that the DC / DC converter 146 can be compensated even if it is used without changing the design. Variations in the behavior of the machine load can be made inconspicuous, and the auxiliary battery can be prevented from rising.

[Embodiment 2]
In the first embodiment, by setting an optimum value as the management lower limit voltage Vb_lim, both battery protection and DC / DC converter performance maintenance are achieved. This improved the practicality. However, during actual vehicle travel, there may be sudden fluctuations in the power consumption of the PCU, such as when a grip occurs after slipping on the wheel. Due to a delay in control, the input voltage of the DC / DC converter is precisely adjusted. There are cases where it cannot be stopped at an optimum value (for example, 195 V).

  Although the frequency of occurrence of such a phenomenon is considerably low, considering this, it is desirable to set a higher voltage as the management lower limit voltage Vb_lim. However, setting a higher voltage as the management lower limit voltage Vb_lim also means that the performance of the battery is not used to the limit, and therefore the performance of outputting the vehicle power is reduced. Therefore, a higher voltage is set as the management lower limit voltage Vb_lim only when such a phenomenon is predicted to occur.

  With reference to FIG. 3 again, the second embodiment will be described. The control device 15 sets a management lower limit voltage in a slip detection unit 156 that detects a slip of a wheel driven by a motor and a discharge allowable power calculation unit. And a battery management lower limit voltage setting unit 152. The battery management lower limit voltage setting unit 152 sets the management lower limit voltage to the first voltage value when the slip detection unit 156 does not detect a slip, and temporarily detects when the slip detection unit 156 detects a slip. Therefore, the management lower limit voltage is set to a second voltage value higher than the first voltage value.

  FIG. 8 is a flowchart illustrating motor generator drive control by control device 15 executed in the second embodiment. The processing of each step shown in FIG. 8 is realized by the control device 15 (FIG. 2) functioning as each control block shown in FIG.

  Referring to FIGS. 3 and 8, HV control unit 150 determines whether or not motor generator current Im2 is larger than threshold value Ith in step S1A. Thereby, the HV control unit 150 determines whether or not there is slip and grip on the wheel. Note that the occurrence of slip and grip may be detected by other methods such as detecting the rotation of a wheel.

  When the battery management lower limit voltage setting unit 152 receives the determination result of the presence or absence of the occurrence of slip, the battery management lower limit voltage setting unit 152 variably sets the minimum allowable voltage (lower limit voltage) Vb_lim allowed for the battery 10 according to the determination result. That is, if Im2> Ith is satisfied in step S1A, the process proceeds to step S2A, and if Im2> Ith is not satisfied, the process proceeds to step S10.

  In step S2A, battery management lower limit voltage setting unit 152 sets management lower limit voltage Vb_lim of battery 10 to voltage VI2 (for example, 199 V).

  In this case, the management lower limit voltage Vb_lim is equal to or higher than the lower limit voltage (for example, 192V) allowed for the battery 10, and the DC / DC converter 146 can maintain the output at a constant value (for example, 15V). It is set to a voltage (for example, 195 V in FIG. 4) or higher.

  Further, the lower limit voltage (for example, 192 V) allowed for battery 10 is equal to or lower than the voltage of battery 10 (for example, 195 V in FIG. 4) at which DC / DC converter 146 can maintain a constant value output (for example, 15 V). .

  On the other hand, in step S10, battery management lower limit voltage setting unit 152 sets management lower limit voltage Vb_lim of battery 10 to voltage VI1 (for example, 195 V).

  Also in this case, the control lower limit voltage Vb_lim is a voltage equal to or higher than the lower limit voltage (for example, 192V) allowed for the battery 10, and the DC / DC converter 146 can maintain its output at a constant value (for example, 15V). (For example, 195V in FIG. 4) or higher. Among them, particularly in the case of step S10, the DC / DC converter 146 is set equal to the voltage of the battery 10 that can maintain the output at a constant value (for example, 15 V) as the management lower limit voltage Vb_lim.

  The processes in steps S20 to S70 are the same as those already described with reference to FIG.

  In the power supply device shown in the second embodiment, fluctuations in the output voltage of the DC / DC converter 146 are less likely to occur.

[Embodiment 3]
To reduce the number of battery cells, it is easy to execute in units of battery packs.

FIG. 9 is a diagram for explaining the configuration of the battery 10.
Referring to FIG. 9, battery 10 includes 17 battery packs 10-1 to 10-17 connected in series. In such a configuration, each battery pack includes 10 to 12 battery cells connected in series.

  For example, if the number of battery cells in the battery pack is 12, and the allowable lower limit voltage per cell is 1V, the voltage of one battery pack is 12V. The total voltage of the 17 battery packs (the lower limit voltage allowed for the battery 10) is 204V. Here, if the number of battery packs is reduced to 16 for cost reduction, the lower limit voltage allowed for the battery 10 is 12V × 16 = 192V.

  However, in this case, the voltage becomes lower than the voltage (195 V) at which the DC / DC converter 146 can output a constant value (for example, 15 V).

Therefore, in some battery packs, the number of battery cells is finely adjusted.
FIG. 10 is a diagram illustrating a configuration of a battery pack in which the number of battery cells is finely adjusted.

  Referring to FIGS. 9 and 10, battery 10 includes a plurality of battery packs 10-1 to 10-17 connected in series. The battery pack 10-17, which is one of the plurality of battery packs 10-1 to 10-17, has a lower limit voltage allowed for the power supply and a power supply voltage at which the voltage converter can maintain the output of the second power supply voltage. Therefore, the number of battery cells connected in series is adjusted by removing some of the battery cells. Then, the battery pack 10-17 removes some of the plurality of battery cells (four out of six) and connects the bus bars BB1 to BB4 which are connection conductors for conducting the opened part. Including.

  Specifically, battery pack 10-17 includes two battery cells CELL1 and CELL2 connected in series, and bus bars BB1 to BB4 for connecting four empty spaces (dummy spaces). In this way, the lower limit voltage allowed for the battery 10 is 12V × 16 + 1 + 1 × 4 = 196V, which can be substantially equal to 195V required for the DC / DC converter 146 to output a constant value. it can. Then, as shown in FIG. 6, the management lower limit value Vb_lim is set to 195 V, and the discharge allowable power Wout is limited.

  In this way, optimal battery protection can be achieved by combining the lower limit value for voltage limitation for battery protection and the power supply voltage required for the DC / DC converter 146 by finely adjusting the number of battery cells. realizable.

  Each functional block constituting the above control means has been described as functioning as software realized by a CPU (Central Processing Unit) that is the control device 15 executing a program stored in the storage unit. However, it may be realized by hardware. Such a program is recorded on a recording medium and mounted on the vehicle.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  10 battery, 10-1 to 10-17 battery pack, 12 voltage sensor, 15 control device, 17 sensor output, 30 power output device, 35 accelerator pedal, 40 differential gear, 50L, 50R front wheel, 60L, 60R rear wheel, 70L, 70R Front seat, 80 Rear seat, 100 Hybrid vehicle, 110 Converter, 120 Smoothing capacitor, 131, 132 Motor drive device (Inverter), 140 Converter / inverter control unit, 146 DC / DC converter, 147 Auxiliary battery, 148 Supplement Load, 150 HV control unit, 152 battery management lower limit voltage setting unit, 154 discharge allowable power calculation unit, 156 slip detection unit, BB1 to BB4 bus bar, CELL1, CELL2 battery cell, ENG engine, MG1, MG2 Over data generator.

Claims (3)

A power supply device for driving a high voltage motor for driving a vehicle and supplying power to a low voltage auxiliary load,
A high voltage power supply,
A motor driving device that receives supply of electric power from the power source and drives the motor according to a driving force command value;
A voltage converter that receives a first power supply voltage from the power supply and outputs a second power supply voltage to the auxiliary load;
A control device for generating the driving force command value,
The controller is
A discharge allowable power calculation unit that calculates discharge allowable power of the power supply so that the first power supply voltage, which is the voltage of the power supply, does not fall below a management lower limit voltage;
A controller that outputs the driving force command value so that power consumption of the motor corresponding to the driving force command value does not exceed the discharge allowable power,
The control lower limit voltage is a voltage equal to or higher than a lower limit voltage allowed for the power supply, and is set to be equal to or higher than the voltage of the power supply at which the voltage converter can maintain the output of the second power supply voltage. And power supply. The controller is
A slip detector for detecting slip of a wheel driven by the motor;
A management lower limit voltage setting unit for setting the management lower limit voltage in the discharge allowable power calculation unit,
The management lower limit voltage setting unit sets the management lower limit voltage to a first voltage value when a slip is not detected by the slip detection unit, and temporarily detects a slip when the slip detection unit detects the slip. The power supply device according to claim 1, wherein the management lower limit voltage is set to a second voltage value higher than the first voltage value. The power supply is
Including a plurality of battery packs connected in series;
Each of the plurality of battery packs is provided with a space for accommodating a plurality of battery cells,
At least one of the plurality of battery packs is configured to match a lower limit voltage allowed for the power supply with a voltage of the power supply that allows the voltage converter to maintain the output of the second power supply voltage. A connection conductor for removing a part of the battery cells and adjusting the number of the plurality of battery cells connected in series and removing the part of the plurality of battery cells to make the opened part conductive The power supply device according to claim 1, comprising:

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