JP2008195089A - Power supply device and drive force control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply stable power to a load device even when switching to power of a power generator only in a power supply device having two kinds of power sources of the power generator and a battery. <P>SOLUTION: A power supply device which has a power supply source of a power generator 7 to be driven by torque of an engine 2 and a chargeable/dischargeable battery 16 and supplies power from the power supply source to a motor 4. If it is determined that a demand power from the motor 4 exceeds or possibly exceeds the power which can be output from the battery 16, in a state at least the battery 16 is electrically connected to the motor 4, the power supply device controls output power from the power generator 7 into a state possible to supply the demand power and switches the buttery 16 into a non-connection state when an electric current flowing the battery 16 becomes zero. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply device capable of supplying power from two types of power supplies to a load device such as a motor, and a vehicle driving force control device including the power supply device.

As an example of a power supply device having two types of power sources that can be electrically connected to a motor that is a load device, there is a hybrid vehicle described in Patent Document 1, for example.
In Patent Document 1, a fuel cell and a battery are provided as power sources. When the remaining capacity of the battery is high, the battery is used as a power source. When the remaining capacity is low, the motor is driven using the fuel cell as a power source.

For example, when switching from a battery to a fuel cell, considering the time delay of the response of the fuel cell, the battery is used to compensate for the shortage of the fuel cell power, and the target power is output from the fuel cell. At this point, the changeover switch is controlled so that only the fuel cell is the power source (see paragraph 0135).
JP 2001-224105 A

Here, when a generator and a battery are assumed as the two types of power sources, the power of the motor (and the inverter) is simply generated from the battery because the responsiveness of the generator is slow against the load fluctuation of the motor. When switching to a machine instantaneously, the load on the generator changes suddenly, and the output voltage and output current of the generator may fluctuate and stable power may not be supplied.
The present invention has been made paying attention to such points, and a power supply device having two types of power sources, ie, a generator and a battery, can provide stable power even when the power is switched to only the generator. The issue is to enable supply to

In order to solve the above-mentioned problems, the present invention uses a generator driven by torque in an internal combustion engine or the like, a generator, and a chargeable / dischargeable power storage unit as a power supply source, and the load device from the power supply source A power supply device for supplying power to
If it is determined that at least the power storage unit is electrically connected to the load device and the required power of the load device exceeds or exceeds the outputable power of the power storage unit, the output power of the generator is The power storage unit is controlled to be in a state where power can be supplied, and when the current flowing through the power storage unit becomes zero, the power storage unit is switched to a disconnected state.

According to the present invention, when switching from a state where power is supplied at least from the power storage unit to a state where power is supplied only by the generator, fluctuations in the supplied voltage and current can be suppressed and smooth power source switching is possible. It becomes.
For example, when used as a power supply device for a vehicle driving force control device, it is possible to reduce or reduce the torque fluctuations of wheels driven by a motor when switching power.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a four-wheel drive vehicle including a power supply device of the present invention. FIG. 2 is a configuration diagram of a power electronics unit related to the motor drive control.
(Constitution)
As shown in FIG. 1, in the vehicle of this embodiment, left and right front wheels 1L and 1R are main drive wheels driven by an engine 2 that is an internal combustion engine, and left and right rear wheels 3L and 3R can be driven by a motor 4. Is a secondary driven wheel.

  For example, a main throttle valve and a sub-throttle valve are interposed in the intake pipe line of the engine 2. The throttle opening of the main throttle valve is adjusted and controlled according to the amount of depression of the accelerator pedal. The sub-throttle valve uses a step motor or the like as an actuator, and the opening degree is adjusted and controlled by a rotation angle corresponding to the number of steps. Therefore, by adjusting the throttle opening of the sub-throttle valve to be less than or equal to the opening of the main throttle valve by a command from the engine control unit, independent of the driver's accelerator pedal operation (accelerator opening), The output torque of the engine 2 can be adjusted.

The output torque Te of the engine 2 is transmitted to the left and right front wheels 1L and 1R through the transmission and the reference gear 5. Further, a part of the output torque Te of the engine 2 is transmitted to the generator 7 via the endless belt 6, so that the generator 7 has a rotation speed Ng obtained by multiplying the rotation speed Ne of the engine 2 by the pulley ratio. Rotate.
The generator 7 becomes a load on the engine 2 according to the field current Ifg adjusted by the 4WD control unit 20, and generates power according to the load torque. The magnitude of the power generated by the generator 7 is determined by the magnitude of the rotational speed Ng and the field current Ifg. FIG. 10 shows output characteristics with the field current of the generator 7 as a variable. In FIG. 10, the horizontal axis indicates the current of the generator 7, and the vertical axis indicates the generator voltage. As shown in this figure, when the generator current increases, the generator voltage decreases due to the internal impedance of the generator 7 and the electron reaction. The rotational speed Ng of the generator 7 can be calculated from the rotational speed Ne of the engine 2 based on the pulley ratio.

The electric power generated by the generator 7 can be supplied to the inverter 9 via the junction box 10.
In addition, a battery 16 is connected to the inverter 9 in parallel with the generator 7, and the electric power of the battery 16 can be supplied to the inverter 9 via the power supply switch 17. Electrical connection / disconnection between the battery 16 and the inverter 9 is switched by a power source switch 17. The power supply switch 17 performs a switching operation according to a command from the 4WD control unit 20. Here, the battery 16 constitutes a chargeable / dischargeable power storage unit. Reference numeral 22 denotes a battery control unit that controls the battery 16.

That is, this embodiment includes two types of power sources, namely, a generator 7 and a battery 16 as the power source of the motor 4, and at least one power of the generator 7 and the battery 16 can be supplied to the AC motor 4 via the inverter 9. It has become. In addition, it is set as the capacitor | condenser input type which installed the small capacitor 15 in parallel with the input circuit.
The motor 4 is a field winding type synchronous motor, and includes a rotor having a field winding and a stator on which a three-phase winding for generating a rotating magnetic field is wound. The motor 4 rotates by the interaction between the magnetic field generated by passing a current through the field winding of the rotor and the magnetic field generated by the three-phase winding of the stator. Further, when the rotor is rotated by an external force, an electromotive force is generated at both ends of the three-phase winding due to the interaction of these magnetic fields, and a power generation operation is performed. That is, it is possible to supply the regenerative power generated by the power generation operation to the battery 16. In this embodiment, a field winding type synchronous motor is applied as the motor 4, but a permanent magnet type synchronous motor or induction motor having a permanent magnet in the rotor can also be applied. The motor 4 is controlled to a command value by the motor control unit 21.

The drive shaft of the motor 4 can be connected to the rear wheels 3L and 3R via the speed reducer 11 and the clutch 12.
In the junction box 10, a relay for connecting and disconnecting the inverter 9 and the generator 7 is provided. In a state in which this relay is connected, the DC power supplied from the generator 7 via the rectifier 12 is converted into a three-phase AC in the inverter 9 and supplied to the motor 4.

Further, in the junction box 10, a generator voltage sensor 13 for detecting a generated voltage and a generator current sensor 14 for detecting a generated current that is an input current of the inverter 9 are provided. These detection signals are controlled by 4WD. Is output to the unit 20. Further, a resolver is connected to the drive shaft of the motor 4 and outputs a magnetic pole position signal θ of the motor 4.
In addition, a battery voltage Vb sensor 18 that detects the voltage of the battery 16 and a battery current Ib sensor 19 that detects the current of the battery 16 are provided, and the sensors 18 and 19 output detected signals to the 4WD control unit 20.

The clutch 12 is a wet multi-plate clutch, for example, and performs fastening and releasing according to a command from the 4WD control unit 20. In this embodiment, the clutch as the fastening means is a wet multi-plate clutch. However, for example, a powder clutch or a pump-type clutch may be used.
Each wheel 1L, 1R, 3L, 3R is provided with a wheel speed sensor. Each wheel speed sensor outputs a pulse signal corresponding to the rotation speed of the corresponding wheel 1L, 1R, 3L, 3R to the 4WD control unit 20 as a wheel speed detection value.

  The 4WD control unit 20 includes an arithmetic processing unit such as a microcomputer, for example. The wheel speed signals detected by the wheel speed sensors 27FL to 27RR, the output signals of the voltage sensor 13 and the current sensor 14, and the motor 4 Are input to the output signal of the resolver connected to the accelerator pedal, the accelerator opening corresponding to the amount of depression of an accelerator pedal (not shown) which is a driving force indicator, and the like.

The motor control unit 21 performs known vector control shown in FIG. 4 from the motor torque command value Tt and the motor rotation speed Nm. Then, the switching control signal of the three-phase power element is output to the inverter 9 to control the three-phase alternating current.
As shown in FIG. 3, the 4WD control unit 20 includes a motor command calculation unit 20A, a required power calculation unit 20B, a motor induced voltage calculation unit 20C, a SW switching determination unit 20D, a generator control unit 20E, and a clutch control unit 20F. Is provided.

  As shown in FIG. 5, which is a block diagram, the motor command calculation unit 20 includes a front / rear rotation speed difference calculation unit 20Aa, a vehicle speed calculation unit 20Ab, a first motor driving force calculation unit 20Ac, a second motor driving force calculation unit 20Ad, The motor torque command value Tt is calculated from the wheel speed difference between the front and rear wheels calculated based on the wheel speed signal of the four wheels and the accelerator pedal opening signal, which includes the select high unit 20Ae and the rear wheel TCS control unit 20Af. .

That is, first, the front-rear rotation speed difference calculation unit 20Aa calculates the front-rear rotation difference ΔV based on the following equation based on the wheel speed signals Vfr to Vrr of the four wheels.
ΔV = (Vfr + Vfl) / 2− (Vrr−Vrl) / 2
Then, based on the front-rear rotation difference ΔV, a map stored in advance by the first motor driving force calculation unit 20Ac is calculated, and the first motor driving force TΔV is calculated and output to the select high unit 20Ae described later. The first motor driving force TΔV is set so that the front-rear rotation difference ΔV is increased and proportionally larger.

On the other hand, the vehicle speed calculation unit 20Ab calculates the vehicle speed signal V by selecting low the wheel speed signals of the four wheels and the total driving force F generated by the vehicle. Here, the total driving force F is obtained by the sum of the front wheel driving force estimated from the torque converter slip ratio and the rear wheel driving force estimated from the motor torque command value Tt.
The second motor driving force calculation unit 20Ad calculates the second motor driving force Tv. Specifically, the calculation is performed with reference to a map stored in advance based on the vehicle speed V output from the vehicle speed calculation unit 20Ab and the accelerator opening degree Acc. The second motor driving force Tv is set so as to increase as the accelerator opening Acc increases and to decrease as the vehicle speed V increases.

Next, in the select high unit 20Ae, the first motor driving force TΔV output from the first motor driving force calculation unit 20Ac and the second motor driving force Tv output from the second motor driving force calculation unit 20Ad are calculated. The selected high value is output as the target torque Ttt to the rear wheel TCS control unit 20Af.
Then, based on the rear wheel speeds Vrl and Vrr and the vehicle speed V, rear wheel traction control control is performed by a known method, and a motor torque command value Tt of the motor 4 is output.

Further, as shown in FIG. 6 which is a block diagram, the required power calculation unit 20B is based on the following formula based on the motor torque command value Tt calculated by the motor command calculation unit 20 and the motor rotation speed Nm. 4 calculates the power Pm required.
Pm = Tt × Nm
Furthermore, based on the motor required power Pm, the generator required power Pg to be output by the generator 7 is calculated based on the following equation. The generator required power Pg must be output more than the motor required power Pm by the efficiency of the motor / inverter.
Pg = Pm / Иm
Here, Иm is the motor / inverter efficiency. The motor / inverter efficiency Иm is calculated using an efficiency map based on the motor torque command value Tt and the motor rotation speed Nm.

  Further, the motor induced voltage calculation unit 20C calculates the induced voltage of the motor and outputs it to the SW switching determination unit 20D. Since the motor induced voltage is determined from the motor rotational speed, the motor field current, and the motor current, as shown in FIG. 7, the motor induced voltage map using the motor rotational speed, the motor field current, and the motor current as variables. Is calculated and stored in advance, and the motor induced voltage is calculated using the motor induced voltage map based on the inputted motor rotation speed, motor field current, and motor current.

  Further, the SW switching determination unit 20D performs processing along the flow shown in FIG. In other words, it is activated at every predetermined sampling. First, in step S10, the SOC (State Of Charge) of the battery 16 is calculated from the current current Ib and the voltage Vb. Subsequently, in step S20, the SOC of the battery 16 is calculated. If it is determined whether or not the SOC of the battery 16 is smaller than the predetermined threshold, the process proceeds to step S70. On the other hand, when the SOC of the battery 16 is equal to or greater than the predetermined threshold value, the process proceeds to step S30.

In step S30, the battery voltage Vb and the battery current Ib are used as variables, the current battery output possible power Pb is calculated based on a preset battery 16 SOC map, and the process proceeds to step S40.
Here, the battery 16 has characteristics as shown in FIG. FIG. 11 shows the battery current Ib on the horizontal axis and the battery voltage Vb on the vertical axis. The solid line is an isoelectric line in each SOC, and the battery voltage Vb decreases due to the internal impedance of the battery 16 as the battery current Ib increases. Further, the output increases as the SOC increases. Based on FIG. 8, the battery SOC map is set.

In step S40, it is determined whether the required power Pm of the motor 4 is smaller than the battery output possible power Pb. If the battery output possible power Pb is larger than the required power Pm, the process proceeds to step S50, and the battery output possible power Pb is If it is less than the required power Pm, the process proceeds to step S70.
In step S50, it is determined whether or not the motor induced voltage is larger than the battery voltage Vb. If the motor induced voltage is larger, the process proceeds to step S70. On the other hand, when the battery voltage Vb is larger, the process proceeds to step S60.

In step S <b> 60, assuming that the battery 16 can supply power, an ON signal is output to the power supply switch 17 to enable the battery 16 to supply power.
On the other hand, in step S70, the battery current Ib is monitored, and when it is detected that the battery current Ib has become zero, an off signal is output to the power source switch 17. That is, in step S70, it is determined whether or not the battery current Ib is zero. When zero is detected, an off signal is output to the power supply switch 17 in step S80, and the process ends. If not, the process returns to step S70. Step S70 is repeated.

Further, the generator control unit 20E performs the process of the block diagram as shown in FIG.
That is, the power to be generated by the generator 7 is calculated by subtracting the battery output possible power Pb from the required power Pm calculated by the required power calculation unit 20B. If the battery output possible power Pb is larger than the required power Pm, the power to be generated by the generator 7 is set to zero. Next, a generator voltage command is calculated by dividing the power to be generated by the generator 7 by the generator current. At this time, when the generator voltage command is larger than the upper limit voltage (failure voltage), it is limited to the upper limit voltage. The upper limit voltage is set to 60 V, for example, and is set from the rating of the inverter element and the design of the generator 7 and the motor 4.

Further, the generator voltage command and the generator voltage are compared to determine a voltage deviation, and PI control is performed to determine and output a field current Ifg to be a generator voltage command.
The gain of the PI control is changed by previously obtaining a P gain map and an I gain map using the rotation speed of the generator 7 as a parameter. In addition, the FF (feed forward) term is obtained in advance as an FF map using the voltage difference of the generator voltage and the rotation speed of the generator 7 as parameters, and is added to the PI output value.

Although FIG. 9 shows an example in which the generated voltage is controlled, the field current Ifg may be obtained and controlled by detecting (or estimating) the generated field magnetic current.
Further, as shown in FIG. 3, the clutch control unit 20F controls the state of the clutch 12, and controls the clutch 12 to be in a connected state while it is determined to be in the four-wheel drive state. For example, the clutch control unit 20F performs control as follows.
・ Clutch on when the vehicle is stopped when the 4WD switch is on ・ Clutch on when the motor target torque is not 0 ・ Clutch off when the motor target torque is 0 ・ Protection when the motor 4 speed exceeds the allowable speed Because of the clutch off ・ Clutch off when 4WD switch is off

(Function and effect)
In a vehicle equipped with the driving force control device having the above-described configuration, the vehicle is driven by front wheels (drive wheels) that are directly driven by the engine when the 4WD switch is off. In this state, the clutch 12 is in an off state.
Next, the operation in the four-wheel drive state in a state where the clutch 12 is connected by turning on the 4WD switch or the like will be described. The present invention is processing in this state.
A motor torque command value Tt is determined according to the accelerator opening, and the required power calculation unit 20B calculates the required power Pm of the motor 4 based on the motor torque command value Tt and the current motor rotation speed Nm.
At this time, if the output power Pb of the battery 16 is larger than the required power Pm of the motor 4 and the battery voltage Vb is larger than the motor induced voltage, it is determined that the required power Pm can be supplied by the power of the battery 16. Thus, the ON state of the power supply switch 17 is maintained, and power is supplied from only the battery 16 to the inverter 9.

  Further, when the accelerator pedal is depressed, an increase in driving force is required and the required power Pm increases, and when the required power Pm exceeds the outputable power Pb of the battery 16, the generator control unit 20E causes the generator 7 to Start power generation. Then, the field current of the generator 7 increases and the voltage of the generator 7 rises. At this time, power is supplied only to the battery 16 until the voltage of the generator 7 exceeds the voltage of the battery 16. Further, when the generator voltage becomes equal to the battery voltage Vb and the generator 7 generates power, the generated power starts to supply power to the load device. Along with this, the current of the battery 16 decreases and the current of the generator 7 increases. When the battery current Ib decreases, the voltage of the battery 16 increases. When the battery current Ib becomes zero, the power switch is turned off and the battery 16 is electrically disconnected from the inverter 9 to supply power. Consists only of the generator 7.

FIG. 12 is a diagram illustrating the movement of the operating points of the battery 16 and the generator 7 when the power source (power supply) is switched from the battery 16 to the generator 7, and FIG. 13 is a time chart thereof.
First, until time t1, the required power Pm is small and the power can be supplied only by the battery 16 (the battery output possible power Pb is larger than the required power Pm and the battery voltage Vb is larger than the motor induced voltage) ) Is P1 in FIG. At this time, since the generator 7 is not generating power, the current and voltage are zero.

  At time t1, when the accelerator pedal is depressed and the required power Pm increases, and it is determined that the battery 16 alone cannot supply power, the generator 7 starts power generation. Then, the field current of the generator 7 increases at time t2, and the voltage of the generator 7 increases accordingly, and the voltage of the generator 7 and the voltage of the battery 16 become equal at time t2. Until this time t2, power is supplied only to the battery 16.

  Furthermore, when the voltage of the generator 7 and the voltage of the battery 16 become equal, and the voltage of the generator 7 increases as the field current of the generator 7 increases from time t2 to time t3, the generator 7 power Supply to the inverter 9 and the motor 4 which are the load devices is started. At this time, in the battery 16, the current decreases as the voltage increases, and in the generator 7, the current increases as the voltage increases. At time t3, the current of the battery 16 becomes zero, and power is supplied only to the generator 7. From time t2 to t3, the power supply is in the area of the battery 16 and the generator 7. P2 is the operating point at that time.

Subsequently, at time t4, it is determined that the generator 7 is generating power and the current of the battery 16 has become zero, and the power switch 17 is turned off. In FIG. 13, the time width from t3 to t4 is set large for easy understanding, but it is actually a very short time width.
Furthermore, the field current of the generator 7 is increased, the current and voltage of the generator 7 are increased, and the required power Pm is generated by the generator 7.

  Thus, for example, if the battery 16 is small, the battery 16 is mainly used as a power source when the required power Pm is low, such as at low speed or low torque. The generator 7 is used as a power source when the required power Pm is high, such as when the vehicle speed is high or when the torque is high, or when the SOC of the battery 16 is low. If the system voltage is sufficient at the battery voltage Vb, such as when the vehicle speed is medium speed or medium torque, but the power is insufficient at the battery 16, both the battery 16 and the generator 7 are connected. Used as a power source.

Here, the generator 7 becomes a load on the engine 2 and is not efficient enough to convert mechanical energy into electrical energy. On the other hand, in the present embodiment, when the required power Pm is small as described above, the motor 4 is driven only by the battery 16, that is, the generator 7 does not generate power.
In addition, by complementing the power shortage in the battery 16 with the generator 7, the required power Pm can be reliably output.

  Further, since the required power Pm is larger than the power that can be output from the battery 16, when switching from the battery 16 to the power supply only to the generator 7, the battery 16 is connected to the inverter 9 after the battery current Ib becomes zero. By changing to the electrically disconnected state, the voltage and current do not fluctuate greatly at the time of switching, and stable power can be supplied to the motor 4 that is the load device.

It is a schematic structure figure concerning an embodiment based on the present invention. It is a schematic diagram of the power electronics part which concerns on embodiment based on this invention. It is a figure which shows the structure of the 4WD control part which concerns on embodiment based on this invention. It is a figure which shows the structure of the motor control part which concerns on embodiment based on this invention. It is a figure which shows the structure of the motor command calculating part which concerns on embodiment based on this invention. It is a figure which shows the structure of the request | requirement power calculating part which concerns on embodiment based on this invention. It is a figure which shows the structure of the motor induced voltage calculating part which concerns on embodiment based on this invention. It is a figure which shows the process of SW switching judgment part which concerns on embodiment based on this invention. It is a figure which shows the structure of the generator control which concerns on embodiment based on this invention. It is a figure which shows the characteristic of a generator. It is a figure which shows the characteristic of a battery. It is a figure which shows the example of operation | movement. It is an example of the time chart of this embodiment.

Explanation of symbols

2 Engine (Internal combustion engine)
4 Motor (load device)
7 Generator 9 Inverter 16 Battery 17 Power switch 20 Motor command calculation unit 20A Motor command calculation unit 20B Required power calculation unit 20C Motor induced voltage calculation unit 20D Switch determination unit 20E Generator control unit 20F Clutch control unit 21 Motor control unit Pb Battery output possible power Pg Generator required power Pm Motor required power

Claims (4)

A power supply device that has a generator and a chargeable / dischargeable power storage unit as a power supply source for supplying power, and supplies power to the load device from the power supply source,
A changeover switch that switches between electrical connection and non-connection between the load device and the power storage unit, and a generator control unit that controls the output power of the generator,
When the required power of the load device is less than or equal to the power that can be output from the power storage unit, at least the power storage unit of the generator and the power storage unit is electrically connected to the load device to supply power, and the required power is stored. If the output power of the generator is determined to exceed or may exceed, the output power of the generator is controlled so that the required power can be supplied, and when the current flowing through the power storage unit becomes zero, the power storage unit is A power supply device that switches to a non-connected state.   The generator control unit sets a power generation target power based on the required power of the load device and the power that can be output from the power storage unit, and controls the output of the generator to the power generation target power. The power supply device described in 1.   3. The power supply device according to claim 1, wherein when the generator control unit determines that the required power of the load device can be supplied only by the power storage unit, the generator does not generate power. A driving force control device for a vehicle, comprising: an internal combustion engine that drives main driving wheels; a motor that can drive the driven wheels; and a power supply device that supplies power to a motor as a load device.
The power supply device is configured by the power supply device according to any one of claims 1 to 3, and the generator is driven to rotate by the driving force of the internal combustion engine. Force control device.

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