JP2007245765A - Vehicle drive controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle drive controller which performs stable motor torque control by a combination of a dynamo and an AC motor. <P>SOLUTION: A target output power PG to be outputted by the dynamo 7 is calculated on the basis of a motor needed power Pm needed by a motor 4, and the dynamo 7 is controlled at a target operation point wherein a torque instruction value Tt calculated on the basis of the target output power PG is efficiently generated. In this case, an upper limit of a target voltage Vt of the target operation point is set according to an engine speed Ng. A torque instruction value Tm for the motor 4 is calculated on the basis of a present output voltage V and an output current I of the dynamo 7, and the motor 4 is controlled on the basis of the torque instruction value Tm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle drive control device that drives a generator with a heat engine (for example, an engine that is an internal combustion engine) that drives a main drive shaft, and drives an AC motor with the output of the generator.

As a conventional vehicle drive control device, there is known a device in which a driven shaft is driven by a direct current motor driven by electric power of a generator and a drive torque is controlled by controlling a field current of the direct current motor. (For example, refer to Patent Document 1).
JP 2001-239852 A

  However, in the above conventional vehicle drive control device, since the motor torque is controlled by applying a DC motor, it is necessary to increase the armature current of the DC motor in order to increase the torque. Since there is a limit in the life of brushes of DC motors, there is a limit in the increase in armature current, and there is an unresolved problem that it is difficult to apply to heavy vehicles or that 4WD performance cannot be improved. .

By the way, it is conceivable to control the motor torque by applying an AC motor + inverter configuration instead of a DC motor. However, it is generally known that the control response of the generator is low and the motor control response by the inverter is high. When such a generator and an inverter are combined, the output voltage and output current of the generator may fluctuate depending on the control state of the inverter serving as an electric load. Need to work.
For example, in the process in which the torque command rapidly decreases, there is an unresolved problem that the decrease in the generator output is delayed, and the component may be damaged when the generator output voltage exceeds a predetermined value (fail voltage).

  Even in a process where the engine speed rapidly increases, the generator output voltage may exceed the fail voltage. FIG. 18A shows the relationship between the generator field current Ifg and the generated voltage Vdc. The curve in the figure is a characteristic line of field current Ifg-generated voltage Vdc at a predetermined engine speed Ng, and curves A and B show the difference in engine speed Ng. This characteristic line is such that the generated voltage Vdc increases as the field current Ifg increases, and there is a region C where the increase rate of the generated voltage Vdc with respect to the increase in the field current Ifg of the generator is slow.

For example, when a large current Ifg1 flows through the field at the operating point a0 in the region C on the characteristic line A, when the engine speed Ng increases, the characteristic line changes from the curve A to the curve B, and the generated voltage Vdc becomes To rise. Therefore, the generator voltage Vdc is attempted to be reduced by reducing the field current Ifg in the generator control. However, in the region C, even if the field current Ifg is reduced, the generated voltage Vdc does not easily drop, so the field current Ifg is reduced. Even if it decreases from Ifg1 to Ifg2, the operating point is a point b0 on the characteristic line B. As a result, power generation becomes excessive (the power generation voltage Vdc exceeds the fail voltage threshold V _max ), resulting in a high voltage fail.

That is, as shown in FIG. 18B, when the engine speed increases when operating at the point a1 on the output possible characteristic line St1 of the generator, the output possible characteristic line changes from St1 to St2, exceeds the fail threshold voltage V _max operating point shifts from the point a1 to the point b1.
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and a vehicle drive control device capable of performing stable motor torque control by a combination of a generator and an AC motor. It is intended to provide.

  In order to achieve the above object, in the vehicle drive control device according to the present invention, the larger the engine speed, the more the generator is driven by fluctuations in the field current of the generator with respect to changes in the generated voltage due to fluctuations in the engine speed. The operation is performed in a region where the generated voltage change rate, which is the change in generated voltage, is large.

  According to the present invention, as the engine speed increases, the generator is operated in a region where the rate of change in generated voltage is large. For example, even if the engine speed increases and the generated voltage increases, the generator By reducing the field current, the generated voltage can be easily reduced, and a high voltage failure can be prevented. As a result, it is possible to prevent the parts from being damaged and to obtain an effect that stable motor torque control can be performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram when the present invention is applied to a four-wheel drive vehicle.
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 which is a heat engine (internal combustion engine), and left and right rear wheels 3L and 3R are This is a driven wheel that can be driven by the motor 4.

  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 equal to or less than the opening of the main throttle valve, the engine output torque can be reduced independently of the driver's operation of the accelerator pedal. That is, the adjustment of the opening degree of the sub-throttle valve is the driving force control that suppresses the acceleration slip of the front wheels 1L, 1R by the engine 2.

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 in accordance with the field current Ifg adjusted by the 4WD controller 8, and generates power in accordance with 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. 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.

  FIG. 2 is a diagram showing the structure of the field current drive circuit of the generator 7. As shown in FIG. 2A, this circuit applies a configuration in which a constant voltage power source such as a 14V battery 7a of a vehicle and an output voltage of the generator itself are selected as a field current power source. Is connected to the field coil 7b to switch the transistor 7c. In this case, when the generator output is lower than the battery voltage Vb, the battery voltage Vb becomes a power source for the field coil 7b in a separate excitation region, the generator output increases, and the output voltage Vg is equal to or higher than the battery voltage Vb. Then, the output voltage Vg of the generator is selected as a self-excited region and becomes a power source for the field coil 7b. That is, since the field current value can be increased by the power supply voltage of the generator, the generator output can be significantly increased.

In the field current drive circuit, only the 14V battery 7a of the vehicle (only the separate excitation region) may be applied as the field current power source as shown in FIG. 2 (b).
The electric power generated by the generator 7 can be supplied to the motor 4 via the junction box 10 and the inverter 9. 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 addition, the motor 4 of this embodiment is an AC motor. Moreover, the code | symbol 13 in a figure shows a difference gear.

In the junction box 10, a relay for connecting and disconnecting the inverter 9 and the generator 7 is provided. In a state where this relay is connected, DC power supplied from the generator 7 via a rectifier (not shown) is converted into three-phase AC in the inverter 9 to drive the motor 4.
The junction box 10 is provided with a generator voltage sensor that detects a generated voltage and a generator current sensor that detects a generated current that is an input current of the inverter 9. These detection signals are sent to the 4WD controller 8. Is output. 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.

The clutch 12 is a wet multi-plate clutch, for example, and performs fastening and releasing according to a command from the 4WD controller 8. 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 27FL, 27FR, 27RL, 27RR. Each wheel speed sensor 27FL, 27FR, 27RL, 27RR outputs a pulse signal corresponding to the rotation speed of the corresponding wheel 1L, 1R, 3L, 3R to the 4WD controller 8 as a wheel speed detection value.

  The 4WD controller 8 includes an arithmetic processing unit such as a microcomputer, for example, and includes wheel speed signals detected by the wheel speed sensors 27FL to 27RR, output signals of voltage sensors and current sensors in the junction box 10, An output signal of a resolver connected to the motor 4 and an accelerator opening corresponding to an amount of depression of an accelerator pedal (not shown) are input.

As shown in FIG. 3, the 4WD controller 8 includes a target motor torque calculation unit 8A, a generator control unit 8B as a field control means, a target motor torque determination unit 8C, a motor control unit 8D, a TCS control unit 8E, and a clutch control unit 8F. Is provided. The target motor torque determination unit 8C and the motor control unit 8D constitute motor control means.
The target motor torque calculation unit 8A calculates a motor torque command value Tt from the wheel speed difference between the front and rear wheels calculated based on the wheel speed signals of the four wheels and the accelerator pedal opening signal.

FIG. 4 is a block diagram showing details of the target motor torque calculator 8A. First, the front / rear rotation difference calculation unit 81 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 (1)
Then, based on the front-rear rotation difference ΔV, the map stored in advance by the first motor driving force calculation unit 82 is referred to calculate the first motor driving force TΔV and output it to the select high unit described later. The first motor driving force TΔV is set so that the front-rear rotation difference ΔV is increased and proportionally larger.

The vehicle speed calculation unit 83 calculates a vehicle speed signal V by selecting low the wheel speed signal 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 calculator 84 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 83 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 85, the first motor driving force TΔV output from the first motor driving force calculation unit 82 and the second motor driving force Tv output from the second motor driving force calculation unit 84 are obtained. The selected high value is output to the rear wheel TCS control unit 86 as the target torque Ttt.
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 torque command value Tt of the motor 4 is output.

The generator control unit 8B performs power generation control described later based on the torque command value Tt from the target motor torque calculation unit 8A, and controls the field current Ifg of the generator 7.
The target motor torque determination unit 8C outputs a torque command value Tm for performing motor control based on the state of the generator 7. Specifically, the torque command value Tm of the motor 4 is calculated from the output voltage V and the output current I of the generator 7.
That is, the torque command value Tm is a motor torque corresponding to the current operating point (voltage / current) of the generator output, and is calculated based on the following equation.
Tm = (V × I × Иm) / Vm (2)

  In this embodiment, as will be described later, the output of the generator 7 is controlled with the operating point at which the generator 7 and the motor 4 are at the optimum efficiency as a target. Therefore, it can be considered that the current output voltage V and output current I of the generator 7 are operating points close to the operating point at which maximum efficiency is achieved. By calculating the torque command value Tm based on the above and performing motor control with this torque command value Tm, the operation at an efficient operating point can be maintained.

The motor control unit 8D performs known vector control shown in FIG. 5 from a torque command value Tm output from a later-described target motor torque determination unit 8C different from the torque command value Tt and a motor rotation speed Vm. Then, the switching control signal of the three-phase power element is output to the inverter 9 to control the three-phase alternating current.
The TCS controller 8E generates an engine generated drive torque demand signal for the ECM by a known method based on the engine generated drive torque demand signal Tet from the engine torque controller (ECM), the front wheel rotational speeds Vfr and Vfl, and the vehicle speed V. Front wheel traction control control is performed by returning Te.
The clutch control unit 8F controls the state of the clutch 12, and controls the clutch 12 to be in a connected state while determining that it is in the four-wheel drive state.

FIG. 6 is a block diagram showing details of the generator control unit 8B that performs power generation control of the generator 7.
The generator control unit 8B includes a motor required power calculation unit 101, a target generated power calculation unit 102, a generated power limit unit 103, a target generated power determination unit 104, and a target operating point setting unit as a target operating point setting unit. Unit 105, target voltage limiting unit 106 as target voltage limiting unit, and generated power control unit 107 as generator output control unit, and controls field current Ifg of generator 7.

Based on the torque command value Tt calculated by the target motor torque calculator 8A and the motor rotation speed Vm, the motor required power calculator 101 calculates the power Pm required for the motor 4 based on the following equation.
Pm = Tt × Vm (3)
Based on the required motor power Pm output from the required motor power calculation unit 101, the target generated power calculation unit 102 calculates the required generator power Pg that the generator 7 should output based on the following equation.
Pg = Pm / Иm ……… (4)
Here, Иm is the motor efficiency. That is, the generator required power Pg must be output by the motor efficiency higher than the motor required power Pm.

The generated power limiting unit 103 outputs generated power limit values PL1 and PL2. The power limit value PL1 is an upper limit value for preventing the generated power from exceeding the power determined according to the transmittable torque of the belt that drives the generator 7, and is calculated based on the following equation.
PL1 = Tb × ωg × Иg (5)
Here, Tb is the torque that can be transmitted to the belt, ωg is the rotational speed of the generator 7, Иg is the generator efficiency, and PL1 is the maximum amount of power that the generator 7 can generate when the belt-transmittable torque is Tb. Equivalent to.

That is, the power limit value PL1 is proportionally increased as the rotational speed ωg of the generator 7 increases as shown in FIG.
The power limit value PL2 is an upper limit value for preventing the generated power from exceeding electric power that may cause engine stall or drivability deterioration due to excessive engine load. This limit value PL2 is given from an engine torque controller (ECM).

As shown in FIG. 7B, the power limit value PL2 is calculated to be larger as the rotational speed ωg of the generator 7 is larger and the accelerator opening Acc is larger.
Then, the calculation results of the target generated power calculating unit 102 and the generated power limiting unit 103 are input to the target generated power determining unit 104, the generator required power Pg and the power limit values PL1 and PL2 are selected, and the generator A target output power PG is calculated.

FIG. 7C shows a case where the generator required power Pg is the smallest of the generator required power Pg and the power limit values PL1 and PL2. In this case, the generator required power Pg at the current speed is The target output power PG is selected.
First, the target operating point setting unit 105 calculates a motor torque command value Tt based on the following expression based on the target output power PG output from the target generated power determining unit 104, that is, the motor usable power.
Tt = (PG × Иm) / Vm (6)

  Next, the input voltage and input current of the inverter 9 that can efficiently generate the motor torque command value Tt, that is, the target voltage Vt and the target current It of the generator 7 are determined within the range of the motor usable power PG. Specifically, as shown in FIG. 8, the intersection of the constant power line P corresponding to the motor usable power PG and the maximum efficiency operating dotted line η indicated by the broken line is a target operating point (Vt, It) of the generator 7. Select as

In general, the generator efficiency is high at high voltage and low current, and the motor efficiency does not change much except when it is at a very low current. It is desirable to work. Further, since the system has an upper limit voltage V _max (for example, 60 V) and an upper limit current I _max (determined by the inverter element rating and the generator / motor design. For example, 30 A), the voltage becomes the upper limit voltage V _max . When approaching, an operating point at which the current value increases with a substantially constant or slight increase in voltage is selected, and eventually the current value increases up to the upper limit current I _max . The continuous line of these operating points is the maximum efficiency operating dotted line η, and this maximum efficiency operating dotted line η is stored in advance.

In the target voltage limiting unit 106, the target voltage Vt obtained by the target operating point setting unit 105 and a limiting voltage that is a voltage limiting value for setting an upper limit on the target voltage Vt calculated by the limiting voltage calculation process described later. The magnitude of Vtt is compared, and the smaller value is output to the generated power control unit 107 as the final target voltage Vt.
Then, the generated power control unit 107 controls the field current Ifg so that the output voltage V of the generator 7 becomes the target voltage Vt. Specifically, as shown in FIG. 9, the generator field current value is fed back while monitoring the actual generator field current Ifg so that the deviation between the target voltage Vt and the output voltage V becomes zero. .

First, a deviation ΔV between the output voltage V from the generator voltage sensor and the target voltage Vt is input to the PID control unit 121, and the PID control unit 121 outputs a target field current Ift such that the deviation ΔV becomes zero. .
In the present embodiment, a field current sensor as a field current detection means is provided to detect the actual generator field current Ifg. Then, a deviation ΔIf between the actual field current Ifg detected by the field current sensor and the target field current Ift is obtained and output to the PID control unit 122. The PID control unit 122 controls the real field current Ifg so that the deviation ΔIf becomes zero.
Thereby, the output voltage V of the generator 7 coincides with the target voltage Vt. That is, the current operating point determined from the output voltage V and output current I of the generator 7 matches the target operating point.

FIG. 10 is a flowchart showing a limit voltage calculation processing procedure executed by the target voltage limiter 106. This limit voltage calculation process is executed as a timer interruption process at predetermined time intervals. First, in step S1, the target motor torque Tt is detected, and the process proceeds to step S2. In step S2, the motor rotation speed Nm is detected, and the process proceeds to step S3.
In step S3, the required power Pg of the generator 7 is calculated based on the target motor torque Tt and the motor rotation speed Nm. Here, the generator required power Pg is calculated based on the above equations (3) and (4).
Next, in step S4, the current generator speed Ng is detected, and the process proceeds to step S5.

In step S5, the allowable field current Ifg0, which is the upper limit value of the field current Ifg of the generator 7, is calculated based on the map stored in advance based on the current generator rotational speed Ng. This map generator rotational speed Ng on the horizontal axis and the vertical axis represents the allowable field current Ifg0, allowable field current Ifg0 in the region of the generator rotational speed Ng is 0 to a predetermined value fixed at the maximum value Ifg _MAX In a region where the generator rotational speed Ng is equal to or greater than a predetermined value, the allowable field current Ifg0 is set to be smaller than the maximum value Ifg _MAX as the generator rotational speed Ng increases.

Next, in step S6, the current temperature of the field coil is detected, and the process proceeds to step S7. Here, the temperature of the field coil is detected using a temperature sensor such as a thermistor as temperature detecting means. Note that the temperature may be calculated by detecting the current value when a predetermined voltage is applied.
In step S7, based on the temperature of the field coil, the temperature coefficient K is calculated based on a previously stored map. This map takes the field coil temperature on the horizontal axis and the temperature coefficient K on the vertical axis. In the region where the temperature ranges from 0 to a predetermined value, the temperature coefficient K is fixed to the maximum value “1”, and the temperature is equal to or higher than the predetermined value. In this region, the temperature coefficient K is set to be smaller than “1” as the temperature increases.

  Next, in step S8, the field current Ifg1 (= Ifg0 × K) obtained by correcting the allowable field current Ifg0 calculated in step S5 with the temperature coefficient K calculated in step S7, and the current generator rotation Based on the number Ng, an output possible characteristic line (VI characteristic) of the generator 7 is calculated. The output possible characteristic line calculated here is a generator output characteristic line with the rotational speed of the generator and the field current as parameters, and when the field current Ifg1 is given at the rotational speed Ng, This is the characteristic that shows the voltage and current that the machine can output.

Next, in step S9, based on the VI characteristic calculated in step S8, a VP characteristic having the voltage V on the vertical axis and the power P on the horizontal axis is obtained, and calculated in step S3. The voltages Vdc1 and Vdc2 at the intersection with the generator required power Pg are calculated, and the process proceeds to step S10.
In step S10, the voltages Vdc1 and Vdc2 are selected high, and the process proceeds to step S11. In step S11, the minimum required voltage Vdcmin is calculated based on the target motor torque T and the motor rotation speed Nm, and the process proceeds to step S12.

  In step S12, it is determined whether or not the select high result max (Vdc1, Vdc2) in step S10 is larger than the minimum required voltage Vdcmin calculated in step S11. If max (Vdc1, Vdc2)> Vdcmin. In step S13, max (Vdc1, Vdc2) is set as the limit voltage Vtt, and the result of selecting low the limit voltage Vtt and the target voltage Vt set by the target operating point setting unit 105 is finally obtained. The target voltage Vt is output to the generated power control unit 107, and then the limit voltage calculation process is terminated.

  On the other hand, when the determination result in step S12 is max (Vdc1, Vdc2) ≦ Vdcmin, the process proceeds to step S14, and a map stored in advance is determined based on the deviation ΔV between max (Vdc1, Vdc2) and Vdcmin. The torque reduction coefficient K2 is calculated with reference. This map is set such that the deviation ΔV is taken on the horizontal axis and the torque reduction coefficient K2 is taken on the vertical axis, and the torque reduction coefficient K2 gradually decreases from “1” as the deviation ΔV increases.

Next, the process proceeds to step S15, a new target motor torque Tt is calculated by multiplying the target motor torque Tt by the torque reduction coefficient K2, and the process proceeds to step S2.
In this way, the torque command value Tt corresponding to the target output power PG to be output from the generator 7 calculated from the power Pm required by the motor 4 can be efficiently generated as the target voltage Vt at the operating point. Then, the generator control is performed with the result of selecting low the limit voltage Vtt set according to the engine speed Ng as the final target voltage Vt.

  FIG. 11 shows a conceptual diagram of setting the limit voltage Vtt. Curves N1 to N3 in the figure are characteristic lines of the field current Ifg and the generated voltage Vdc when the engine speed Ng is fixed, and the curves N1 to N3 indicate differences in the engine speed Ng. Since the magnetic flux contributing to the generated voltage Vdc is determined by the physique and design of the generator, in the high field current region in this characteristic line, the rate of increase of the generated voltage Vdc with respect to the increase in the generator field current Ifg becomes dull.

  As shown in FIG. 11, the allowable voltage (limit voltage) Vtt1 of the generated voltage Vdc when the engine speed Ng is small (when the characteristic line is N1) is the maximum voltage that can be output by the generator at the engine speed at that time. The voltage value is set equal to the so-called saturation voltage Vs1. Further, the allowable voltage (limit voltage) Vtt3 of the generated voltage Vdc when the engine speed Ng is large (in the case of the characteristic line N3) is set to a voltage value significantly smaller than the saturation voltage Vs3 at the engine speed at that time. . That is, as the engine speed Ng increases, the limit voltage Vtt, which is a voltage limit value for setting an upper limit on the target voltage Vt, is set to be smaller than the maximum voltage that can be output by the generator 7 at the current engine speed Ng.

This corresponds to increasing the limit amount of the field current Ifg of the generator 7 as the engine speed Ng increases. That is, the allowable field current Ifg0, which is the upper limit value of the field current Ifg when the engine speed Ng is small, is set to a relatively large Ifg1, and the allowable field current Ifg0 when the engine speed Ng is large is The allowable field current Ifg0 is set to be smaller as the engine speed Ng is larger.
In this way, by limiting the target voltage Vt (or field current Ifg), the higher the engine speed, the more the generator 7 is allowed to change the field of the generator 7 against the change in the generated voltage Vdc due to the fluctuation of the engine speed Ng. The operation is performed in a region where the change rate of the generated voltage, which is the change of the generated voltage Vdc due to the fluctuation of the magnetic current Ifg, is large.

Next, the operation of this embodiment will be described.
First, consider a case where the torque command value increases while the engine speed Ng is low. FIG. 12 is a diagram showing an operating point (voltage / current) at the output of the generator 7, that is, the input of the inverter 9, and is assumed to be at a point a1 on the output possible characteristic line of the generator represented by the curve St1. The constant power line corresponding to the torque command value T1 at this time is indicated by a hyperbolic curve P1.

Assuming that the torque command value has increased from T1 to T2 from this state, the target operating point setting unit 105 sets the efficient operating point a ^* on the constant power line P2 corresponding to the torque command value T2 as the target operating point. Is set. Further, in the target voltage limiter 106, in the limit voltage calculation process of FIG. 10 described above, since the engine speed Ng is low, the field current Ifg of the generator 7 is not limited in step S5, and the allowable field current is not limited. since Ifg0 is set to the maximum value Ifg _MAX, never target voltage Vt is limited. Therefore, the target voltage Vt set by the target operating point setting unit 105 is selected as it is as the final target voltage Vt, and the generated power control unit 107 sets the field voltage so that the current output voltage V matches the target voltage Vt. The current Ifg is controlled to increase. The output possible characteristic line of the generator at this time is a curve St2, and the operating point is a ^* .

It is assumed that the engine speed Ng has increased from this state. When the output potential characteristic line of the generator changes from St2 to St2 ′ due to the increase in the engine speed Ng, the operating point shifts to the intersection a2 between the output possible characteristic line St2 ′ and the constant power line P2, and thus the generated voltage Vdc. Rises. However, the generated voltage Vdc at this time because it does not exceed the fail voltage threshold V _max, it is possible to ensure stable operation.

 Next, consider a case where the torque command value increases from T1 to T2 while the engine speed Ng is high. In this case, the field current Ifg of the generator 7 is limited in step S5 of FIG. 10, and the allowable field current Ifg0 is set to a relatively small value, so that the target voltage Vt is greatly limited. become. At this time, if the limit voltage Vtt is smaller than the target voltage Vt set by the target operating point setting unit 105, the limit voltage Vtt is selected as the final target voltage Vt in step S13, and the generated power control unit 107 The field current Ifg is controlled to increase so that the output voltage V of the output voltage V becomes equal to the target voltage Vt (= Vtt). That is, as shown in FIG. 13, the output possible characteristic line of the generator 7 changes from the curve St1 to the curve St2, and the generator operating point shifts from the point a1 to the point a2.

When the field current Ifg is not limited (the target voltage Vt is not limited) as in the conventional device, an efficient operating point a3 on the constant power line P2 corresponding to the torque command value T2 is the target operating point. Therefore, the field current control is performed so that the output possible characteristic line of the generator 7 changes from the curve St1 to the curve St3.
Assuming that the engine speed Ng has increased with the operating point at the point a2 on the output possible characteristic line St2 of the generator 7, the output possible characteristic line changes from St2 to St2 ′, and the operating point is a2 ′. Therefore, the generated voltage Vdc rises. However, since the generated voltage Vdc at this time does not exceed the fail voltage threshold value V _max , stable operation can be ensured.

On the other hand, in the state where the field current Ifg is not limited (the target voltage Vt is not limited) and the operating point is at the point a3 on the output possible characteristic line St3 of the generator 7 as in the conventional device, the engine speed Assuming that Ng has increased, the output possible characteristic line changes from St3 to St3 ′, and the operating point shifts to a3 ′, so that the generated voltage Vdc increases. Generated voltage Vdc at this time exceeds the fail voltage threshold V _max.
As described above, when the engine speed Ng is high, the field current Ifg is limited (target voltage Vt is limited), and the generator 7 is used in a region where the power generation voltage change rate is large. It is possible to prevent a high voltage failure with respect to an increase in Ng.

Next, the operation and effect of this embodiment will be described based on the field current Ifg-generated voltage Vdc characteristic diagram of FIG.
When the engine speed Ng is relatively large, as shown in FIG. 14A, when operating at a point α1 (field current Ifg1) where the rate of change in the generated voltage is relatively large, the engine speed is from N1. Assume that it has risen to N2. At this time, the voltage change due to the fluctuation of the engine speed Ng is ΔV1. Since the generator 7 operates in a region where the rate of change in the generated voltage is relatively large, if the field current Ifg is decreased from Ifg1 to Ifg2, the generated voltage Vdc tends to drop, and the voltage change due to fluctuations in the field current Ifg ΔV2. Since the voltage change due to the fluctuation of the engine speed Ng and the voltage change due to the fluctuation of the field current Ifg are balanced (ΔV1 = ΔV2), there is no change in the generated voltage Vdc and the operation is performed at the point α2. Therefore, stable motor torque control can be maintained without causing a high voltage failure.

Further, when the engine speed Ng is relatively small, as shown in FIG. 14B, when operating at a point β1 (field current Ifg3) where the rate of change in the generated voltage is relatively small, the engine speed is Assume that N3 has risen to N4. At this time, the voltage change due to the fluctuation of the engine speed Ng is ΔV3, and the voltage change when the field current Ifg is decreased from Ifg3 to Ifg4 is ΔV4. Since the voltage change due to the fluctuation of the engine speed Ng is larger than the voltage change due to the fluctuation of the field current Ifg (ΔV3> ΔV4), the power generation voltage Vdc rises and operates at the point β2. electrostatic Vdc does not exceed the fail voltage threshold V _max. Therefore, stable motor torque control can be maintained.

When the engine speed is low Ng, if the engine rotational speed Ng increases rapidly, although a situation where the power generation voltage Vdc may exceed the fail voltage threshold V _max soaring, before the generated voltage Vdc is applied to the fail voltage threshold V _max Because the field current Ifg drops, the high voltage fail is not caused. Therefore, the generator can be operated in a region where the rate of change in the generated voltage is relatively small, that is, in a region where the target voltage is high, which is advantageous in terms of the efficiency of the generator and the output responsiveness.

  As described above, in the present embodiment, the field current of the generator is controlled from the power required by the motor, and the motor is controlled from the output voltage and output current of the current generator. Since the value and the command value to the motor are different, the control system diverges or operates with very poor efficiency even when the generator control with low response and the motor control with high response are combined. Can be suppressed.

  Also, as the engine speed increases, the generator is operated in a region where the power generation voltage change rate, which is the change in the generated voltage due to the change in the generator field current with respect to the change in the generated voltage due to the change in the engine speed, is large When the engine speed is high, the generated voltage can be easily reduced by reducing the field current even when the engine speed is increased and the generated voltage is increased. Can be prevented. Further, when the engine speed is low, it is possible to ensure operation in a region where the efficiency of the generator and the output response are high.

In addition, the upper limit is set for the target voltage of the generator that is calculated based on the power required by the motor by the voltage limit value according to the engine speed, so the region in which the generator is operated is limited according to the engine speed. can do.
In addition, since the voltage limit value is set to be smaller than the maximum voltage that can be output by the current engine speed as the engine speed increases, the generator increases in the region where the power generation voltage change rate increases as the engine speed increases. Can be operated.

In addition, since an upper limit is set for the target voltage of the generator by setting an upper limit for the field current of the generator, the voltage limit value can be set appropriately, and the rate of change in the generated voltage increases as the engine speed increases. The generator can be operated in a large area.
Furthermore, since the voltage limit value is changed according to the temperature of the field coil, the higher the field coil temperature, the lower the generator target voltage (increase the target voltage limit), and the temperature It is possible to prevent the parts from being damaged due to the rise.
Furthermore, since the field current of the generator is monitored and feedback control is performed so that the actual field current follows the target field current, the output voltage can surely follow the target voltage.

  In the present embodiment, the result of selecting low the target voltage Vt set by the target operating point setting unit 105 and the limit voltage Vtt calculated by the target voltage limiting unit 106 is the final target voltage Vt. However, the present invention is not limited to this. The field current Ifg required for the generator 7 is calculated based on the target operating point (Vt, It) set by the target operating point setting unit 105. The final target voltage Vt of the generator may be calculated from the result of selecting the field current Ifg and the allowable field current Ifg0 set according to the engine speed Ng.

  In the present embodiment, the case where the generated power control unit 107 follows the target field current Ift while monitoring the actual field current Ifg of the generator 7 has been described. However, the present invention is not limited to this. As shown in FIG. 15, the generator field current may be PWM-controlled so that the deviation between the target voltage Vt and the output voltage V becomes zero. In this case, first, the deviation ΔV between the target voltage Vt and the output voltage V is output to the PID control unit 123.

The PID control unit 123 controls the PWM duty ratio D of the field current drive circuit of the generator 7 according to the deviation ΔV. Specifically, the PWM duty ratio D is increased when Vt> V, and the PWM duty ratio D is decreased when Vt <V.
For example, the following PID control is performed.
D = α × (Vt−V) + β × ∫ (Vt−V) (7)

  FIG. 16 is a characteristic diagram showing the relationship between the PWM duty ratio D and the field current Ifg. The horizontal axis represents the PWM duty ratio D, and the vertical axis represents the field current Ifg. As shown in this characteristic diagram, the field current Ifg does not flow when the duty ratio D is 0%, and a lot of the field current Ifg flows as the duty ratio D approaches 100%.

This characteristic is such that the greater the field power supply voltage Vf, the greater the slope, and the smaller the field coil resistance, the greater the slope. If the generator output voltage Vg is less than or equal to the battery voltage Vb, Ifg = A × D, and when Vg> Vb, Ifg = a × Vf × D. Here, a is a constant.
By controlling the PWM duty ratio D thus output by the PWM drive unit 124, the field current Ifg can be controlled, and as a result, the output voltage V of the generator 7 becomes the target voltage Vt. Can be controlled.

As a result, it is possible to control in a loop with a large output voltage and target voltage, including all error factors of field current control due to variations in field current voltage and field coil resistance value. There is no need to provide a sensor, and the cost can be reduced.
In the process of FIG. 15, the processes of the PID control unit 123 and the PWM drive unit 124 correspond to the duty ratio control means.

As shown in FIG. 17, the generated power control unit 107 may feedback control the multiplication value of the field power supply voltage Vf and the PWM duty ratio D. In this case, the deviation ΔV between the output voltage V and the target voltage Vt is input to the PID control unit 125, and PID control shown in the following equation (8) is performed to output the PWM duty ratio D.
Vf × D = α × (Vt−V) + β × ∫ (Vt−V)
D = {α × (Vt−V) + β × ∫ (Vt−V)} / Vf (8)

  As described above, when Vg> Vb, the field current Ifg = a × Vf × D. From this relationship, it is possible to perform feedback control assuming that (Vf × D) is the field current Ifg. That is, by performing feedback control of the product of the field power supply voltage Vf and the PWM duty ratio D, it is possible to obtain a control effect such that the field current Ifg is substantially feedback controlled. In the region where the field power supply voltage Vf is large, the weight of the PWM duty ratio can be set smaller than that at the time of low voltage, so that appropriate control in consideration of the magnitude of the field power supply voltage can be performed. .

  In the present embodiment, the motor torque corresponding to the current operating point of the generator 7 is set as the torque command value Tm in the target motor torque determination unit 8C, but on the output possible characteristic line of the generator 7. The motor torque corresponding to the operating point at which the overall efficiency of the generator 7 and the motor 4 is optimal may be used as the torque command value Tm. At this time, a predetermined margin may be given to the total efficiency, and an operating point at which the total efficiency is equal to or higher than a set value may be selected. Further, instead of the operating point at which the total efficiency of the generator 7 and the motor 4 is optimized, the operating point at which the output power of the generator 7 is maximized, the operating point at which the motor efficiency is optimized, and the generator efficiency are It is also possible to apply an operating point that is optimal, or an operating point that maximizes the product of the overall efficiency of the generator 7 and the motor 4 and the output power of the generator 7.

It is a schematic structure figure showing an embodiment of the present invention. It is a figure which shows the structure of a generator. It is a block diagram which shows the detail of 4WD controller of FIG. It is a block diagram which shows the detail of the target motor torque calculating part of FIG. It is a block diagram which shows the detail of the motor control part of FIG. It is a block diagram which shows the detail of the generator control part of FIG. It is a figure which shows the relationship between an electric power limit value and target output electric power. It is a figure explaining the selection method of a target operating point. It is a block diagram which shows the detail of the generated electric power control part in this embodiment. It is a flowchart which shows the limiting voltage calculation process performed with a limiting voltage calculation part. It is a figure explaining the concept of target voltage restriction. It is a figure explaining operation | movement of this embodiment. It is a figure explaining operation | movement of this embodiment. It is a figure explaining the effect of this embodiment. It is a block diagram which shows another example of the generated electric power control part in this embodiment. It is a characteristic view which shows the relationship between PWM duty ratio D and field current Ifg. It is a block diagram which shows another example of the generated electric power control part in this embodiment. It is a figure explaining operation | movement in a conventional apparatus.

Explanation of symbols

1L, 1R Front wheel 2 Engine 3L, 3R Rear wheel 4 Motor 6 Belt 7 Generator 8 4WD controller 8A Target motor torque calculation unit 8B Generator control unit 8C Target motor torque determination unit 8D Motor control unit 8E TCS control unit 8F Clutch control unit DESCRIPTION OF SYMBOLS 9 Inverter 10 Junction box 11 Reducer 12 Clutch 27FL, 27FR, 27RL, 27RR Wheel speed sensor 101 Motor required power calculating part 102 Target generated power calculating part 103 Generated power limiting part 104 Target generated power determining part 105 Target operating point setting part 106 Target voltage limiter 107 Generated power controller

Claims (9)

A vehicle drive control device comprising: a heat engine that drives main drive wheels; a generator that is driven by the heat engine; and an AC motor that is supplied with electric power from the generator via an inverter to drive the driven wheels In
As the engine speed increases, the generator is operated in a region where the power generation voltage change rate, which is a change in the generated voltage due to the change in the generator field current with respect to the change in the generated voltage due to the change in the engine speed, is large. A vehicle drive control device. A vehicle drive control device comprising: a heat engine that drives main drive wheels; a generator that is driven by the heat engine; and an AC motor that is supplied with electric power from the generator via an inverter to drive the driven wheels In
A field control means for controlling the field of the generator based on the required motor power required by the AC motor; and a motor control means for controlling the AC motor based on the state of the generator. The means includes a target operating point setting unit that sets a target operating point of the generator based on a required motor power required by the AC motor, and a target operating point setting unit based on a voltage limit value corresponding to the engine speed. Target voltage limiting means for setting an upper limit on the target voltage at the target operating point set in (2), and generator output control means for controlling the field of the generator based on the target voltage limited by the target voltage limiting means. A vehicle drive control device comprising:   3. The vehicle drive according to claim 2, wherein the target voltage limiting unit sets the voltage limit value to be smaller than a maximum voltage that can be output by the generator at the current engine speed as the engine speed increases. Control device.   4. The vehicle drive according to claim 2, wherein the target voltage limiting unit sets an upper limit on the target voltage by setting an upper limit on the field current of the generator according to an engine speed. 5. Control device.   Temperature detection means for detecting or estimating the temperature of the field coil of the generator; and the target voltage limiting means is configured to detect the voltage limit value according to the temperature of the field coil detected or estimated by the temperature detection means. The vehicle drive control device according to any one of claims 2 to 4, wherein the vehicle drive control device is changed.   The generator output control means controls the field of the generator so that the output voltage of the generator becomes a target voltage limited by the target voltage limiting means. The vehicle drive control device according to any one of the preceding claims.   Field current detection means for detecting the field current of the generator, the generator output control means, so that the output voltage of the generator becomes a target voltage limited by the target voltage limiting means, 7. The vehicle drive control device according to claim 6, wherein the field current detected by the field current detection means is feedback controlled.   The generator output control means is a duty ratio control for controlling a PWM duty ratio of the field current drive circuit of the generator so that an output voltage of the generator becomes a target voltage limited by the target voltage limiting means. The vehicle drive control device according to claim 6, comprising means.   9. The vehicle drive control device according to claim 8, wherein the duty ratio control means sets the PWM duty ratio in accordance with a power supply voltage of the field current drive circuit.

Images