JPH07303400A - Controller of motor for driving movable body - Google Patents

Abstract

PURPOSE:To extend the travel distance of a movable body by comparing a torque command which is input to a vector controller with a set value and changing a magnetic flux command in accordance with the the comparison result. CONSTITUTION:A previous torque command T* and a preset value which is a value (voltage) obtained through a resistor for setting 85 from a source of D.C. constant voltage are compared by a comparator 88 and the output of the comparator 88 for switching a switch 80 is on/off-controlled. By switching the switch 80, a magnetic flux command PHI* is changed step by step. In other words, the magnetic flux command PHI* is automatically adjusted according to the magnitude of a step-in amount of an accelerator pedal 71. To be more specific, the magnetic flux PHI* is made small when the step-in amount of the accelerator pedal 71 is large and the magnetic flux command PHI* is made large when the step-in amount of the accelerator pedal 71 is small and thereby a motor 1 can be efficiently operated. By this method, the travel distance of a movable body can be extended.

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 driving a moving body such as an electric vehicle.

[0002]

2. Description of the Related Art A conventional technique for weakening the field control of an induction motor of an electric vehicle is disclosed in, for example, Japanese Patent Laid-Open No. 513071 [hereinafter, referred to as "conventional example"]. This conventional example is intended to prevent instability due to a change in disclosed current and reduce magnetic noise.As its configuration, the torque command and the motor speed calculated by the vehicle drive calculation unit are weakened to the field calculation unit. This is an electric vehicle control device with a field weakening control for inputting and calculating a magnetic flux command, delaying a torque command by a torque delay element, performing vector calculation from a reference torque and a magnetic flux command, and performing torque control of an induction motor.

[0003]

However, in this conventional technique, the fact that the magnetic flux command is changed according to the magnitude of the load is not taken into consideration, and the loss of the battery is not taken into consideration. , I could not extend the mileage of electric vehicles. Here, an object of the present invention is to provide a control device for a motor that wipes a bottleneck of a conventional example and drives a moving body having a long travel distance.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to a controller for a moving body driving motor, which drives and controls the moving body driving motor by a vector control inverter for supplying a DC voltage by a battery. In, a moving body drive motor comprising a comparator for comparing a torque command input to the vector control device with a set value, and a magnetic flux command switcher for changing the value of the magnetic flux command according to the output of the comparator. Control device.

[0005]

Since the present invention has such a circuit configuration, one iron loss of the generated loss of the motor (induction motor) depends on the magnetic flux and the driving frequency. Therefore, the magnitude of the magnetic flux command depends on the magnitude of the load. In order to obtain the same output, the copper loss of the other is increased by increasing the magnetic flux of the motor to reduce the current, and the copper loss is reduced. As a result, the magnetic flux is reduced at light load to improve the efficiency.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a circuit configuration when applied to an electric vehicle as an embodiment of the present invention. On the other hand, when the driver depresses the accelerator pedal 7, the torque command T ^* via the variable resistance 73 from the DC constant voltage (source) 72 via a so-called sensor is proportional to the amount of depression of the accelerator pedal 7 previously. , To the torque current calculator 6. On the other hand, the voltage from the DC constant voltage (source) 83 is high due to the resistors 81 and 82 voltage dividing means.
One of the low voltages is output as the magnetic flux command Φ ^* . This magnetic flux command Φ ^* is multiplied by the exciting reactance M of the motor 1 via the coefficient unit 84 and enters the arithmetic unit 51 included in the vector controller 5.

Further, the magnetic flux command Φ ^* is also given to the torque current calculator 6, where the torque command T ^{* is changed} to the magnetic flux command Φ ^*.
The torque current command Iτ ^* is divided by the torque current calculator 6
Output from. The torque current command Iτ ^* is input to the calculator 51 included in the vector controller 5 and also applied to the multiplier 87. In the vector controller 5, based on the input torque current command Iτ ^* and magnetic flux command Φ ^* , the primary current command amplitude I ₁ ^* of the electric motor 1, the torque current command Iτ ^*, and the magnetic flux command Φ ^*.
Calculate and derive the phase angle θ with ^* .

Further, the torque current command I τ ^* is divided by the magnetic flux command Φ ^* in the divider 57 in the vector controller 5 and is multiplied by the coefficient K ₁ of the coefficient unit 52 to calculate the slip frequency ω _s of the electric motor 1. The primary frequency command ω ₁ ^* of the electric motor 1 is calculated by adding the detected value of the actual speed from the pulse oscillator 3 connected to the electric motor 1 to the slip frequency ω _s by the adder 53, and the calculated value is a vector. It is given to the control oscillator 54, where the input of the scalar quantity is converted into the output of the vector quantity and sent to the adder 55. In the adder 55, the vector amount obtained by adding the phase angle θ from the calculator 51 is input to the multiplier 56. This multiplier 56
Then, the primary current command amplitude I ₁ ^* from the calculator 51 and the adder 55
To derive the primary current command i ₁ ^* , obtain the deviation from the actual current of the electric motor 1 from the current transformer 91 in the subtractor 92, and first obtain the coefficient K ₂ in the coefficient unit 9. A torque corresponding to the amount of depression of the electric motor 1 is driven by driving the inverter 4 with a value according to the multiplied current deviation and controlling the inverter (consisting of a self-extinguishing element) using the battery 10 as a power source. Drive with.

By the way, the theoretical theory which is the cause of the present invention will be developed below. FIG. 2 shows the power flow of an electric vehicle drive device using a battery as a power source. That is, the battery supply power is the sum of the motor output power 21, the motor loss 22, the inverter loss 23, the battery loss, and the like. Therefore, in order to extend the one-charge traveling distance of the electric vehicle, it is sufficient to reduce each power loss. Of these losses, the battery loss is mainly copper loss, and is the loss determined by the motor output power 21 if the battery voltage is constant.

The present invention is a method for reducing the inverter loss 23 and the motor loss 22 by switching the magnitude of the magnetic flux according to the required torque. FIG. 3 shows a basic configuration diagram of a battery-driven inverter drive device. In FIG. 3, the loss generated in the inverter 2 that uses the battery 10 as a power source and passes through the smoothing circuit 11 is mainly due to the power transistors T ₁ to
It is divided into the loss of T _{6 and} the loss of the control circuit 100. In addition, the loss of the power transistors T _{1 to} T ₆ is substantially proportional to the motor current I ₁ flowing in the motor 1 because the voltage drop with respect to the flowing current is almost constant.

On the other hand, the loss of the control circuit 100 is constant regardless of the motor current I ₁ . That is, the inverter loss 23 of the inverter 2 when the motor current is I ₁ is set to W _INV
[Watt, hereinafter referred to as “W”] can be expressed by the following equation (1). W _INV = W _K + W _T0 · I ₁ / I ₁₀ ………………………… (1) where W _K is the loss of the control circuit [W] and W _T0 is the motor rated current I ₁₀ . Transistor loss [W], I ₁₀ is the motor rated current [ampere, hereinafter referred to as "A"]

Next, when the motor loss 22 of the loss generated in the motor 1 is W _M , it is expressed by the equation (2). W _M = W _c1 + W _c2 + W _i + W _m ……………………………… (2) where W _c1 is the primary resistance copper loss [W] and W _c2 is the secondary resistance copper loss [W ], W _i is iron loss [W], W _m is mechanical loss [W] where each loss is expressed by the following equations. W _c1 = 3 · r ₁ · (I ₁ ) ² ………………………… (3) W _c2 = 3 · r ₂ · (I ₂ ) ² …………………… ( 4) W _i = K ₁ · [(Φ · f ₁ ) α power] ………… (5) where I ₁ is the motor primary current [A] and I ₂ is the motor secondary current [A] Φ is a motor magnetic flux (Gauss) f ₁ is a primary frequency (Hertz) K ₁ is a constant α = 1.6 to 2 or more From the above, it can be seen that the smaller the magnetic flux and the current, the smaller the loss of the inverter 2 and the motor 1. .

On the other hand, the generated torque T of the motor output power 21 and the motor primary current I ₁ are T = K ₂ · Φ · I ₂ ………………………… (6) where K ₂ is Constant I ₁ = {(I _m ) ² + (I ₂ ) ² } ^1/2 ………………………… (7) where I _m is the magnetizing current [A] I _m = K ₃ Φ ... ……………………………… (8) However, since K ₃ is expressed as a constant, the motor 1 is calculated from the equations (6), (7), (8).
The next current I ₁ becomes I ₁ = [(K ₃ · Φ) ² + {T / (K ₂ · Φ)} ² ] ^1/2 (9), and the current for the required torque T is shown in FIG. Be done.

Therefore, when the required torque T is smaller than the torque T _{0, the} motor primary current I ₁ is smaller when Φ = Φ ₂ than when Φ = Φ ₁ for the motor magnetic flux Φ, and the motor magnetic flux Φ Is also small, the loss of the inverter 2 and the motor 1 is also small. Here, T ₀ is the torque at which the torques T of the magnetic flux Φ ₁ and the magnetic flux Φ ₂ match. For example, when the motor magnetic flux Φ ₁ = 100% and the motor magnetic flux Φ ₂ = 50%, when the required torque T is larger than the torque T ₀ , the motor magnetic flux Φ ₁ = 100% and the required torque T is the torque T _0.
When it is smaller, the energy can be saved by switching to the motor magnetic flux Φ ₂ = 50%.

Therefore, the present invention constitutes the following circuit based on this theory. As described above, in order to extend the traveling distance by performing the energy-saving operation of the moving body, it is possible to reduce the current amount of the generated torque by changing the magnetic flux command Φ ^* according to the magnitude of the torque current command Iτ ^*. By using that principle, it is possible to reduce battery consumption. Here, the present invention relates to a motor (induction motor).
Since one of the generated losses, the iron loss, depends on the magnetic flux and the drive frequency, change the magnitude of the magnetic flux command according to the magnitude of the load.
On the other hand, in order to obtain the same output, the copper loss is reduced by increasing the magnetic flux of the motor to reduce the copper loss, and as a result, the magnetic flux is reduced when the load is light to improve the efficiency.

Therefore, in this embodiment, the above torque command T ^{* is used.}
And DC constant voltage (source) 86 through setting resistance 85
The comparator 88 performs a comparison operation with a preset numerical value, which is (voltage), to control ON / OFF of the switching output of the selector switch 80 from the comparator 88. The magnetic flux command Φ ^* is changed stepwise by switching the switch 80, that is, the magnetic flux command Φ ^* is automatically adjusted depending on the amount of depression of the accelerator pedal 71. This is the accelerator pedal
When the stepping amount of 71 is large, decrease the magnetic flux command Φ ^* ,
When the accelerator pedal 71 is slightly depressed, the magnetic flux command Φ
By increasing ^* , efficient motor operation is performed.

As described above, the changeover switch 80, the resistors 81, 82, 85, the constant voltage (source) 83, 86, and the comparator 88 in this embodiment are used.
Constitutes a magnetic flux command (Φ ^* ) switch. Although the present embodiment has a circuit configuration for performing the two-stage magnetic flux command Φ ^* ,
The method is not limited to this, and the same method can be performed in three or more steps. Further, although the brake pedal is not mentioned, it is omitted because it is the same as the conventional example.

[0018]

As described above, according to the present invention, since the magnetic flux command is adjusted stepwise in accordance with the torque command, the loss in driving the moving body of the electric motor operation by the inverter from the battery is reduced as much as possible. Therefore, it is possible to obtain a special effect that the efficiency is improved and the traveling distance is extended.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing a power flow of an electric vehicle drive device using a battery as a power source.

FIG. 3 is a basic circuit configuration diagram of a battery-driven inverter drive device.

FIG. 4 is a characteristic curve diagram in which the motor magnetic flux of the motor primary current with respect to the required torque of the motor is used as a parameter.

[Explanation of symbols]

1 motor (induction motor) 2 inverter (consisting of self-extinguishing element) 21 motor output power 22 motor loss 23 inverter loss 3 pulse oscillator 4 pulse width modulator (PWM) 5 vector controller 51 calculator 52 coefficient unit (K ₁ ) 53 Adder 54 Vector controlled oscillator 55 Adder 56 Multiplier 57 Divider 6 Torque current calculator (divider) 71 Accelerator pedal 72 DC constant voltage (source) 73 Variable resistance (sensor) 81 Resistance 82 Resistance 83 DC Constant voltage (source) 84 Coefficient unit (1 / M, M is the excitation reactance of the motor 1) 85 Resistance 86 DC constant voltage (source) 88 Comparator 9 Coefficient unit (K ₂ ) 91 Current transformer 92 Subtractor 10 Smoothing circuit 100 control circuit

Claims (1)

[Claims] 1. In a control device for a moving body driving motor, which drives and controls a moving body driving motor by a vector control inverter that supplies a DC voltage from a battery, a torque command input to the vector controlling device is compared with a set value. And a magnetic flux command switcher that changes the value of the magnetic flux command according to the output of the comparator.