JP2001028804A - Motor controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller for controlling a motor without deterioration in steering caused by a difference in revolution speed at turning of the vehicle with respect to an electric vehicle with the induction motors connected to right and left driving wheels and driving the induction motor with a common inverter. SOLUTION: When a vehicle is turned by driving force, a revolution speed difference ΔNs between revolution speed Nin of an induction motor of an inner wheel and revolution speed Nout of an induction motor of an outer wheel is calculated. A control curve is determined by the revolution speed difference ΔNs and output torque T. A primary current according to the control curve is determined, and a sliding speed Ns0 is calculated from the control curve. A driving current revolution speed NI is calculated from the sliding speed Ns0 and the revolution speed Nout. The induction motor is put under sliding-speed control at the driving current revolution speed NI and a primary current value I as a controlling target, the same torque as the outer wheel is generated in the inner wheel, and a deterioration in steering can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for a vehicle that uses a plurality of induction motors for driving the vehicle and drives the vehicle with a common drive device. The present invention relates to a motor control device for a vehicle capable of performing the following.

[0002]

2. Description of the Related Art In an electric vehicle, left and right driving wheels are driven by respective induction motors. Conventionally, for controlling each induction motor, an inverter is provided for each induction motor, and the driving force distribution of the left and right drive wheels calculated from the vehicle running state is independently driven by the inverter.

On the other hand, in order to improve the cost performance of an electric vehicle, it is required to reduce the weight and cost of the vehicle, and the structure of an induction motor control device is simple.
Such a low cost is required. Therefore, it is conceivable that the inverters connected for each induction motor are integrated by one inverter to drive the induction motor intensively.

[0004]

However, when the drive control of the left and right induction motors is performed by a common inverter, the induction motors output torque by the slippage speed (the speed obtained by subtracting the rotation speed of the drive current from the rotation speed of the rotor). Is different, the difference between the rotation speeds of the left and right induction motors causes a difference in output torque based on the difference between the rotation speeds of the left and right induction motors, which affects the behavior of the vehicle. is there.

When the induction motor is in a power running state (rotational speed of rotor <rotational speed of drive current), output torque is as shown in FIG.
As shown in (1), it changes depending on the magnitude of the driving current and the magnitude of the sliding speed. In general, an induction motor used as a power source for an electric vehicle or the like has a slip speed set to N2 and changes the current value of the drive current so that the drive efficiency of the motor is maximized in order to perform control that emphasizes efficiency in general. Controls the output torque.

When a car turns, the rotation speed of the inner wheel becomes lower than the rotation speed of the outer wheel. At this time, for example, if the sliding speed N2 is set in accordance with the induction motor that drives the inner wheels, the sliding speed of the induction motor that drives the outer wheels decreases because the rotation speed of its rotor is high. As shown in FIG. 11, the output torque becomes smaller than that of the inner induction motor in accordance with the sliding speed N1. For this reason, the output torque of the induction motor generated at the time of turning the vehicle is such that the induction motor driving the inner wheels generates an output torque larger by ΔT than the induction motor driving the outer wheels, and There is a problem that turning performance of the vehicle is reduced. The present invention has been made in view of the above problems, and has as its object to provide a vehicle motor control device that does not deteriorate the turning performance of a vehicle even when a plurality of induction motors are driven by a common inverter.

[0007]

According to a first aspect of the present invention, there is provided a motor control device for a vehicle for controlling a plurality of induction motors connected to left and right driving wheels and independently driving the respective driving wheels. Driving means for driving the motor in common;
A drive current value output from the drive means and a current control means for controlling a rotation speed of the drive current, the current control means corresponding to the rotation speeds of the left and right induction motors, each output torque Sliding speed control is performed so as to be the same.

According to a second aspect of the present invention, the current control means performs a slip speed control so as to reduce an output torque from an induction motor having a low rotation speed in accordance with a rotation speed difference between the left and right induction motors. did.

According to a third aspect of the present invention, the current control means detects a rotation speed difference between the left and right induction motors, and the rotation speed difference and a target torque required for the vehicle. Current calculation means for calculating a drive current output by the drive means; slip speed calculation means for calculating a slip speed based on the rotation speed difference and the target torque; and a drive speed based on the slip speed and a predetermined induction motor rotation speed. And a rotation speed calculating means for calculating the rotation speed of the driving current output by the means.

According to a fourth aspect of the present invention, when the vehicle is provided with a cornering sensor, the vehicle further includes a vector control means for controlling the vector of the induction motor and a switching means, and the cornering sensor determines that the vehicle is traveling straight. The switching means switches the induction motor control from the sliding speed control to vector control by the vector control means.

According to a fifth aspect of the present invention, the vector control means compares the rotational speeds of the left and right induction motors, and when the induction motor is in power running control, a low rotation speed is a reference rotation speed, and when the regeneration control is high, a high rotation speed is high. Vector control is performed using the speed as a reference rotation speed.

According to the present invention, the vector control means and the current control means are connected to the drive means via output means having a first-order lag filter.

[0013]

According to the first aspect of the present invention, since the slip speed control is performed so that the output torques of the left and right induction motors become the same, the rotation speed of the induction motor driving the inner wheels decreases when the vehicle turns. As a result, the output torque does not increase, and the vehicle can be turned smoothly.

According to the second aspect of the present invention, the current control means performs the slip speed control so as to reduce the output torque from the induction motor having a low rotation speed according to the difference in the degree of transfer between the left and right induction motors. At the time of turning, it is possible to suppress an increase in output torque in response to a decrease in the rotation speed of the induction motor that drives the inner wheels, and to appropriately adjust the torque distribution during turning of the vehicle.

According to the present invention, when the vehicle is determined to be in a straight running state, the switching means switches the control of the induction motor from the sliding speed control to the vector control, so that the sliding speed control is performed only when the vehicle is cornering. Will be As a result, good torque distribution can be performed during turning, and motor control can be performed with high drive efficiency by vector control in a normal straight traveling state.

According to the fifth aspect of the present invention, the vector control means compares the rotational speeds of the left and right induction motors, and sets a low rotational speed as a reference rotational speed when the induction motor is in power running control, and a high rotational speed during regenerative control. Since vector control is performed as the reference rotation speed, torque distribution can be reduced to wheels that have caused slip or skid, and motor control can be performed in a direction to eliminate slip or skid.

According to the sixth aspect of the present invention, the vector control means and the current control means are connected to the driving means via the output means provided with the first-order lag filter. In addition, a sudden change in control characteristics can be avoided.

[0018]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a block diagram showing the configuration of the embodiment. The induction motors 7L and 7R are motors for driving the vehicle, and are respectively connected to left and right drive wheels (not shown) of the vehicle and are driven independently. Induction motor 7
L and 7R are connected to a common inverter 6. The inverter 6 converts DC power from a vehicle-mounted battery (not shown) into, for example, three-phase AC power and supplies power to the induction motors 7L and 7R to drive the motors.

A cornering sensor 9 is attached to the vehicle, and a detection value (a cornering sensor signal) is output to the cornering determination unit 2. Cornering judgment unit 2
Then, it is determined whether or not the vehicle is in a cornering state based on the input detection value, and the determination result is output to the switching unit 5. The switching unit 5 selects whether to perform vector control or sliding speed control depending on whether the vehicle is in a cornering state. The vector control unit 3 corresponding to the selection result
Alternatively, the sliding speed control unit 4 is operated. For example, a sensor that detects a yaw rate or a steering angle can be used as the cornering sensor.

The operation system of the vehicle outputs an accelerator opening signal, a shift position signal, and a brake signal to the target torque generator 1 as operation signals of the vehicle. The target torque generator 1 calculates a target torque to be output based on the operation signal of the vehicle. The target torque is output to the vector control unit 3 and the sliding speed control unit 4. The vector control unit 3 and the sliding speed control unit 4 provide a primary current value (output current value) as a control value for controlling the induction motor based on the target torque and the rotation speeds NL and NR of the induction motors 7L and 7R.
Calculate I and current frequency ω. The calculated control value is output to the inverter 6 by the output unit 8. The output unit 8 includes a first-order lag filter, and is configured to filter and output the control value. The vector speed controller 3 performs control so as to maximize the driving efficiency of the induction motor. The sliding speed control unit 4 performs control so that the same torque is output to two induction motors.

FIG. 2 is a flowchart showing a control flow in the above configuration. First, in step 100, the target torque creating section 1 receives a vehicle operation signal and detects an accelerator opening A and a shift position from the operation signal. When the brake is depressed, the brake depression amount is detected from the brake signal. The average value of the rotation speeds NL and NR of the induction motors 7L and 7R is used as the vehicle speed.

In step 101, the target torque generator 1 calculates a target torque T0 to be controlled based on the accelerator opening A, the shift position, and the vehicle speed.
This calculation can be performed using, for example, a control diagram shown in FIG. Also, during regenerative braking
The target torque is calculated according to the brake depression amount.

In step 102, the cornering judging section 2 judges whether the vehicle is in a straight running state or a cornering state based on the input cornering sensor signal, and the judgment result is output to the switching section 5. In step 103, the switching unit 5 checks whether or not the vehicle is in a cornering state. In the case of the cornering state, the slide speed control is selected, the slide speed control unit 4 is operated, and the routine proceeds to step 108. If the vehicle is running straight, vector control is selected and the vector control unit 3 is operated, and the routine proceeds to step 104.

In step 104, the vector control unit 3 determines whether power running control or regenerative control is to be performed based on the target torque T0. In the case of regenerative control, the routine proceeds to step 105, and in the case of power running control, the routine proceeds to step 106. In step 105, the rotational speeds NR of the left and right induction motors 7L, 7R,
A reference rotation speed N0 for performing control by extracting a value having a large value from NL is set as a reference rotation speed N0. On the other hand, in step 106, the one having the lower rotation speed is extracted and the reference rotation speed N
Set to 0. As a result, the reference rotation speed N0 becomes the rotation speed of the induction motor in which no slip or skid occurs. Since vector control is performed in a region where the driving efficiency of the induction motor is high, the output torque distribution is reduced to the wheels that have slipped or skid in accordance with their rotational speeds, and the motor is driven in a direction that eliminates slips or skids. Will be.

In step 107, the vector control unit 3 determines a value based on the reference rotational speed N0 and the target torque T0.
A primary current value I and a current frequency ω, which are control values for performing vector control, are calculated. The detailed contents of the vector control are the same as those in the related art, and the description is omitted here. On the other hand, in step 108, the sliding speed control unit 4 calculates a primary current value I and a current frequency ω, which are control values for performing the sliding speed control, based on the target torque T0 and the rotation speeds NL and NR of the induction motors 7L and 7R. . The details of the calculation will be described later.

In step 109, the output unit 8 filters the control value of the induction motor using a first-order lag filter and outputs the result to the inverter 6. In step 110, the induction motors 7L and 7R are driven by the inverter 6 with the primary current value I and the current frequency ω as control targets.

With the above control, vector control is performed when the vehicle is traveling straight. In performing vector control, control is performed on the induction motor with a low rotation speed during power running and on the induction motor with a high rotation speed during regeneration, so the torque output to the wheel that has slipped or skid at each time However, as shown in FIG. 4, the motor drive is performed in a direction in which the slip or skid is reduced, as compared with the non-slip or non-skid wheel.

Next, the slip speed control will be described in detail. FIG. 5 is a characteristic diagram showing a relationship between the sliding speed and the output torque of the motor. In the figure, in the powering region where the output torque is positive, the output torque increases as the slip speed decreases from 0, and when the slip speed reaches a predetermined slip speed, the output torque becomes maximum, and thereafter, the output torque decreases.

In the vector control performed when the vehicle is traveling straight, the control is performed within a range where the output torque is larger than the slip speed at which the output torque is maximum (point B) in order to increase the efficiency. By expanding the control range to a region where the output torque is smaller than the slip speed at which the output torque becomes maximum (point B), the same output torque can be generated even when the slip speed is different. Also,
This characteristic is the same in the regenerative region, and the output torque becomes a negative regenerative torque.

FIG. 6 shows the sliding speed control unit 4 in FIG.
FIG. 3 is a diagram showing a detailed configuration of the embodiment. The rotation speed difference calculator 41 receives the rotation speeds NL and NR of the induction motors 7L and 7R, and calculates a rotation speed difference ΔNS. This calculation value is output to the primary current calculation unit 42 and the sliding speed calculation unit 43. The primary current calculation section 42 has a current calculation map shown in FIG. 7. The current calculation map includes, based on the control characteristics shown in FIG. 5, an output under the condition that the output torques are the same for the induction motors 7L and 7R. In the possible torque range, the correspondence between the rotational speed difference ΔNS and the primary current value I for each torque T is described. Primary current value I is induction motor 7L
And 7R. The primary current calculation unit 42
The torque T borne by each induction motor (target torque T0 /
2) and the rotational speed difference ΔNS between the left and right induction motors,
A primary current value I is obtained from the current calculation map and output.

The slip speed calculation unit 43 has a slip speed calculation map shown in FIG. The slip speed calculation map includes a rotation speed difference ΔNS for each outputable torque based on the control characteristics of FIG. 5 and a slip speed of an induction motor having a high rotation speed during power running and a low rotation speed during regeneration. The correspondence of the speed NS0 is shown. The slip speed calculation unit 43 calculates the slip speed NS0 from the slip speed calculation map based on the torque T (target torque T0 / 2) borne by each induction motor and the rotation speed difference ΔNS between the left and right induction motors.
And outputs it to the current frequency calculation unit 44. The current frequency calculation unit 44 calculates the drive current rotation speed NI from the sliding speed NS0 and the rotation speed of the induction motor, and calculates and outputs the current frequency ω based on the number of poles of the induction motor. The induction motors 7L and 7R are controlled by the inverter 6 with the current frequency ω and the primary current value I as control targets.

Next, the flow of the slip speed control will be described with reference to the flowchart of FIG. That is, step 1
081, the rotation speed difference calculation unit 41
A rotation speed difference ΔNS is calculated from the rotation speeds NL and NR of L and 7R. In step 1082, the primary current calculator 42 calculates a primary current value I as a control target from the current calculation map of FIG. 7 based on the output torque T of each motor calculated from the target torque T0 and the rotation speed difference ΔNS. I do. In step 1083, the sliding speed calculation unit 4
3 calculates a slip speed NS0 as a control target from the slip speed calculation map of FIG. 8 based on the output torque T of each induction motor and the rotation speed difference ΔNS of the left and right induction motors.

In step 1084, the current frequency calculator 44 calculates the current frequency ω according to the following equation. First, the rotation speed NI of the drive current is calculated based on the rotation speed Nout having a larger value and the sliding speed NS0 of the induction motors 7L and 7R during power running. NI = Nout + NS0 At the time of regeneration, the rotation speed Nin and the sliding speed NS having small values are small.
Calculated as 0. NI = Nin−NS0 The current frequency ω is calculated based on the rotation speed NI of the drive current and the number k of poles of the induction motor. ω = NI × k

As described above, in the sliding speed control, the control is performed so that the torque generated in each induction motor is the same in accordance with the rotation speed difference. Is no longer increasing,
The effect that turning is performed smoothly is obtained. The present embodiment is configured as described above, and the motor control is switched according to the vehicle state such as straight traveling or turning, so that control suitable for each state can be performed. By performing the slip speed control at the time of turning, even if a difference occurs in the rotation speeds of the left and right wheels, an increase in output torque is suppressed for wheels having low rotation speeds, and the vehicle can be driven without impairing the turning performance of the vehicle. Further, when the vehicle is traveling straight, normal vector control is performed, so that the induction motor can be driven with high efficiency.
In addition, control is performed with the induction motor with the low rotation speed as the control target during power running and the induction motor with the high rotation speed as the control target during regeneration. Alternatively, the generation of regenerative torque becomes smaller,
Since the induction motor is driven in a direction in which slip or skid is reduced, the vehicle can quickly escape from that state.

In the above embodiment, when the vehicle is cornering, the motor control is switched to the sliding speed control so that the output torque is the same even if the rotation speed difference of the induction motor occurs. As can be seen from the sliding speed control characteristic diagram, in the region exceeding the maximum torque (point B), the output torque decreases as the sliding speed decreases, so that if the sliding speed is further reduced, the rotation speed becomes lower. A smaller torque can be generated for the induction motor.

Next, as a modification, slip speed control for further suppressing the output torque of the induction motor having a low rotation speed will be described with reference to the flowchart of FIG. First, in step 1001, a yaw moment control calculation is performed on the calculated target torque T0 according to the rotational speeds of the left and right induction motors. Thus, the torque Tin output to the inner induction motor and the torque Tout output to the outer induction motor are obtained. Tin is smaller than Tout. In step 1002, a rotation speed difference ΔNS is calculated from the rotation speeds NL and NR of the left and right induction motors.

In step 1003, the rotational speed difference Δ
Under the correspondence relationship between NS, the predetermined torque Tin and the torque Tout, the rotational speed difference ΔNS and the torque Tin and the rotational speed difference ΔNS are obtained from the current operation formula I = f1 (Tout, Tin, ΔNS) obtained by calculating backward from the characteristics of FIG. The primary current value I is determined by Tout. In step 1004, based on the correspondence between the rotational speed difference ΔNS and the predetermined torque Tin and torque Tout, the slip speed calculation formula NS0 = f2 (Tou
t, Tin, ΔNS), the rotational speed difference ΔNS and the torque T
The slip speed NS0 is obtained from in and Tout.

In step 1005, the rotational speed NI of the drive current is calculated by the following equation. At the time of power running, NI = Nout + NS0 At the time of regeneration, NI = Nin−NS0 The current frequency ω is calculated by NI and the number k of poles of the induction motor. ω = NI × k In the above, the calculation of the primary current value and the rotation speed of the drive current is shown by a function. Of course, similarly to the embodiment, the motor characteristics shown in FIG. It can also be calculated from the map.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an embodiment.

FIG. 2 is a flowchart showing a control flow.

FIG. 3 is a control diagram showing a relationship between a vehicle speed and a target torque.

FIG. 4 is an explanatory diagram showing a change in torque distribution when vector control is performed.

FIG. 5 is a diagram showing control characteristics of sliding speed control.

FIG. 6 is a diagram showing a detailed configuration of a subbell speed control unit.

FIG. 7 is a current calculation map for calculating a primary current value.

FIG. 8 is a slip speed map for calculating a slip speed.

FIG. 9 is a flowchart showing a flow of a sliding speed control.

FIG. 10 is a flowchart showing a modification of the sliding speed control.

FIG. 11 is an explanatory diagram showing motor characteristics of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Target torque preparation part 2 Cornering judgment part 3 Vector control part (vector control means) 4 Sliding speed control part (current control means) 5 Switching part (switching means) 6 Inverter (driving means) 7L, 7R Induction motor 8 Output part ( Output means) 9 Cornering sensor 41 Rotation speed difference calculation unit (Rotation speed difference detection unit) 42 Primary current calculation unit (Current calculation unit) 43 Sliding speed calculation unit (Slip speed calculation unit) 44 Current frequency calculation unit (Rotation speed calculation unit) )

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Claims (6)

[Claims] 1. A vehicle motor control device for controlling a plurality of induction motors connected to left and right driving wheels and independently driving the respective driving motors, wherein a driving means for driving each induction motor in common, and the driving means are It has a drive current value to be output and current control means for controlling the rotation speed of the drive current, and the current control means has the same output torque in accordance with the rotation speeds of the left and right induction motors. A motor control device for a vehicle, which performs slip speed control as described above. 2. The method according to claim 1, wherein said current control means performs a slip speed control so as to reduce an output torque from an induction motor having a low rotation speed in accordance with a rotation speed difference between the left and right induction motors. 2. The vehicle motor control device according to claim 1. 3. The current control means includes: a rotation speed difference detecting means for detecting a rotation speed difference between the left and right induction motors; and the driving means outputting the rotation speed difference and a target torque required for a vehicle. Current calculation means for calculating a drive current value; slip speed calculation means for calculating a slip speed based on the rotation speed difference and the target torque; and output of the drive means based on the slip speed and the rotation speed of a predetermined induction motor. 3. A motor control device for a vehicle according to claim 1, further comprising a rotation speed calculating means for calculating a rotation speed of the driving current. 4. A vehicle further comprising a cornering sensor, a vector control means for vector-controlling the induction motor, and a switching means. When the cornering sensor determines that the vehicle is in a straight-ahead state, the switching means comprises 4. The motor control device for a vehicle according to claim 1, wherein the induction motor control is switched from the sliding speed control to the vector control by the vector control means. 5. The vector control means compares the rotation speeds of the left and right induction motors, and sets a low rotation speed as a reference rotation speed during power running control and a high rotation speed during regeneration control. 5. The vehicle motor control device according to claim 4, wherein vector control is performed. 6. The vehicle motor control device according to claim 4, wherein said vector control means and said current control means are connected to said drive means via output means having a first-order lag filter.