JPH05184018A - Drive motor controller for electric automobile - Google Patents

Abstract

PURPOSE:To reduce the power consumption of a drive motor by detecting the load current of the drive motor and then searching a control amount for minimizing thus detected load current. CONSTITUTION:When a cruise control switch (mode selection switch) is depressed to select a cruise mode, a cruise control signal e1 is delivered from the cruise control switch to a main computor 29 thus setting a cruise mode. The main computor 29 performs phase control while sustaining a set vehicle speed and searching an optimal phase difference for sustaining a minimum load current. At that time, phase current of one of phases U, V, W of a DC brushless motor 11 is detected as the load current. According to the constitution, power consumption of the DC brushless motor 11 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive motor controller for an electric vehicle.

[0002]

2. Description of the Related Art Conventionally, in an automobile, an internal combustion engine is used as a drive source, and energy generated by burning gasoline in the engine is converted into torque, which is driven by changing the rotational speed via a transmission. It is designed to be transmitted to the wheel. Then, the gear ratio of the transmission is changed by manual shift or automatic shift,
On a road that needs to travel under various load conditions such as an ordinary road, the vehicle runs at an optimum gear position with low fuel consumption corresponding to the load condition.

However, since an automobile using an internal combustion engine burns gasoline to generate torque, it produces exhaust gas and pollutes the environment. Further, in the idling state, the vehicle does not run even though the engine is rotating, and exhaust gas is further generated in a city where traffic is often congested. Therefore, there is provided an electric vehicle in which part or all of the drive source is replaced with a drive motor, and electric energy is converted into torque and transmitted to the drive wheels (see Japanese Patent Laid-Open No. 1-298905).

In the electric vehicle, for example, a battery is mounted on the vehicle body as a power source, and the drive motor is driven by the current supplied from the battery. In this case, the electric vehicle is provided with a drive motor for each drive wheel, and the vehicle speed is changed by directly controlling the rotation speed of the drive motor.

[0005]

However, although the above-mentioned conventional drive motor control device for an electric vehicle is designed so that the amount of mechanical loss can be suppressed, the load on the traveling road is reduced. In response to changes in conditions, energy consumption is low and highly efficient traveling cannot be performed.

[0006] That is, even on a traveling road that needs to travel under various load conditions such as a general road in an urban area,
Since the drive motor is designed under a certain load condition, the power consumption will be large. The present invention provides a drive motor control device for an electric vehicle, which solves the problems of the conventional drive motor control device for an electric vehicle, can cope with various load conditions, and can reduce the power consumption of the drive motor. The purpose is to

[0007]

Therefore, in the drive motor control device for an electric vehicle according to the present invention, at least a part of the drive force of the vehicle is generated by the drive motor including the stator and the rotor to drive the vehicle. ing. An interlinkage ratio changing means is provided to change the interlinkage ratio at which the magnetic flux generated by the magnetic poles of the stator and the magnetic flux generated by the magnetic poles of the rotor are interlinked.

Therefore, it has a means for detecting the load current of the drive motor and a means for searching for a control amount that minimizes the detected load current. A means for outputting the searched control amount to the interlinkage ratio changing means is provided.

[0009]

According to the present invention, at least a part of the driving force of the vehicle is generated by the drive motor composed of the stator and the rotor as described above, and the vehicle travels. Further, the other part of the driving force may be generated by the engine. An interlinkage ratio changing unit is provided to change the interlinkage ratio at which the magnetic flux generated by the magnetic poles of the stator and the magnetic flux generated by the magnetic poles of the rotor are interlinked. The interlinkage changing means receives the control amount corresponding to the load current and changes the interlinkage.

Further, the control device has a means for detecting the load current of the drive motor and a means for searching for a control amount that minimizes the detected load current. The control device constantly reduces the load current and reduces the power consumption. The control amount searched for is output to the interlinkage ratio changing means. Therefore, it is possible to surely eliminate wasteful power consumption based on the measured value of the load current.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a schematic diagram of a drive motor control device for an electric vehicle showing an embodiment of the present invention, FIG. 2 is a detailed view of a drive motor control device for an electric vehicle showing an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 3 is a perspective view of an electric vehicle equipped with the drive motor controller shown in FIG.

As shown in FIG. 1, a brushless DC motor 11 is provided in each of the four driving wheels of an electric vehicle (FIG. 3) and has a DC power source 12 having a voltage of 240 [V], for example.
It is driven by the current supplied from. The brushless DC motor 11 includes a rotor composed of 6-pole permanent magnets,
It is provided with an electromagnetic coil composed of three-phase windings, that is, a stator coil.

The rotor of the resolver 15 is coaxially coupled to the rotor shaft 13 of the brushless DC motor 11 so that the absolute position of the magnetic pole of the rotor of the brushless DC motor 11 can be detected. There is.
That is, the resolver circuit 16 is connected to the resolver 15, and the resolver circuit 16 connects the resolver 1 with the resolver circuit 16.
5, the AC voltage E _m sin ωt and the AC voltage E _m cos ωt
(Represented by x and y in the figure) is applied, and the resolver 1
5 receives the resolver signal a of the AC voltage E _m sin (ωt + θ), detects the absolute position of the magnetic pole of the rotor, and outputs the excitation position signal b to the current waveform control circuit 17.

The current waveform control circuit 17 is for supplying the brushless DC motor 11 with a current corresponding to the load condition of the electric vehicle, for example, the accelerator depression amount, and corresponds to the required current (torque command). The pulse width modulation (PMW) signal d of the UVW phase having the duty ratio is output to the base drive circuit 28. The stator coil of the brushless DC motor 11 is excited by the bridge circuit 18. The bridge circuit 18 is composed of six power transistors 21 to 26.
The base drive circuit 28 outputs a transistor drive signal c to the bases 1 to 26 as a switching signal. The base drive circuit 28 receives the PMW signal d output from the current waveform control circuit 17 and drives each transistor.

Reference numeral 29 denotes a main computer, and a cruise control signal e ₁ output from a cruise control switch (mode selection switch) is output to an input port of the main computer 29 from an accelerator sensor to correspond to the amount of depression of the accelerator. The accelerator signal e ₂ , the brake signal e ₃ that is output from the brake sensor and corresponds to the amount of brake depression, and the shift position signal e that is output when the shift lever is moved to each range position
₄ , rotation speed (rotation speed) R of brushless DC motor 11
A speed signal e ₅ which is electromagnetically picked up and another signal e ₆ are input.

From the output port of the main computer 29, the current command signal j ₁ for commanding the required current to the current waveform control circuit 17, the rotation direction command signal j ₂ , the regenerative signal j ₃ and The operation command signal j ₄ is
The phase difference command signal p is output to the resolver circuit 16. Further, a power supply circuit 33 is connected to the DC power supply 12, applies a drive voltage q to the bridge circuit 18, and supplies a control power supply voltage r to each control circuit such as the current waveform control circuit 17. Apply. Reference numeral 34 is a smoothing capacitor connected to the input side of the bridge circuit 18, and 35 is a current sensor for the phase current supplied to the brushless DC motor 11. The current sensor 35 is U
The phase current detection signal s and the V phase current detection signal t are output to the current waveform control circuit 17.

Further, as shown in FIG. 2, the resolver circuit 1
6 is an excitation circuit 41, a magnetic pole detection circuit 42, a CPU 43, and R
It is composed of an OM 44 and a D / A converter 45. The resolver 15 is composed of a so-called brushless resolver, has a two-phase stator winding on the stator side and a secondary winding of a rotary transformer, and generates an induced voltage on the rotor side by the stator winding. And a primary winding of a rotary transformer electrically connected to the rotor winding.

The exciting circuit 41 is connected to the resolver 1
The AC voltage E _m sin ωt and the AC voltage E _m cos ωt, which are out of phase with each other by 90 °, are applied to the five stator windings. At this time, the AC voltage E _m phase-modulated by the angle θ from the reference position of the rotating shaft is applied to the rotor winding of the resolver 15.
sin (ωt + θ) is induced. The magnetic pole detection circuit 42 uses the induced AC voltage E _m sin (ωt + θ) and the excitation circuit 4
Based on the resolver excitation frequency sin ωt input from 1, the displacement angle θ from the reference axis of the rotor is obtained, the absolute position of the magnetic pole of the rotor is detected by the displacement angle θ, and
It is output to the CPU 43 as bit digital absolute position data.

When the CPU 43 receives the phase difference command signal p from the main computer 29, it changes the digital absolute position data. That is, the main computer 29 generates the phase difference command signal p in response to the change between the voltage control which is the first control mode and the phase control which is the second control mode, and the CP
Output to U43. Upon receiving the phase difference command signal p, the CPU 43 shifts the digital absolute position data by the phase difference α commanded by the phase difference command signal p. That is, virtual digital absolute position data is generated as if the absolute position shifted by the phase difference α in the rotational direction from the actual absolute position of the magnetic pole is detected, and is output to the ROM 44 as a digital absolute position signal v. ..

The ROM 44 stores three pieces of sine wave data, each of which is out of phase by 2 / 3π. The rotor digital absolute position signal v output from the CPU 43 is converted to a UVW phase sine wave digital signal. Convert to w and output. Then, the sine wave digital signal w is converted into an analog signal z (sin θ, sin (θ +
2 / 3π), sin (θ + 4 / 3π)), and output to the current waveform control circuit 17.

The current waveform control circuit 17 includes a multiplier 61,
It is composed of a current amplifier 62, a comparator 63, and an oscillator (triangular wave carrier) 64 for generating a sawtooth wave. The multiplier 61 includes the D / A converter 4
The analog signal z indicating the absolute position of the magnetic pole of the rotor, which is output from _{No. 5,} is input, and the required current determined based on the load condition, for example, the accelerator signal e ₂ is input as the current command signal j ₁ , and the phase And the amplitude of the specified AC signal g (Isin θ, Isin (θ + 2 / 3π), Isi
n (θ + 4 / 3π)) is output to the current amplifier 62.

The current amplifier 62 has an AC signal g (Isin
θ, Isin (θ + 2 / 3π), Isin (θ + 4 / 3π))
Are the phase currents KIsin θ, KIsin (θ + 2 / 3π), which are respectively supplied to the UVW phases of the brushless DC motor 11,
It is differentially amplified with the feedback signal of KIsin (θ + 4 / 3π) and output to the comparator 63. The comparator 6
To the input terminal of 3, together with the output of the current amplifier 62,
The output from the oscillator 64 is input to the base drive circuit 2 which outputs the PMW signal d whose phase and duty ratio are determined.
8 and the power switching circuit 66 of the bridge circuit 18
Output to.

By the way, in the electric vehicle of the present invention, the cruise traveling can be performed by the driver's selection when traveling in the suburbs or on the highway. Therefore, a cruise control switch is provided near the driver's seat. The cruise control switch is composed of a momentary switch so that the normal running mode and the cruise running mode can be alternately selected each time the switch is pressed. Further, the cruise traveling mode can be canceled and switched to the normal traveling mode by changing the accelerator opening by a predetermined value or more, or by stepping on the brake.

When the cruise mode is not selected and the normal mode is selected, the brushless DC motor 11 performs voltage control with emphasis on acceleration. That is, when the driver selects the normal traveling mode, the CPU 43 directly outputs the digital absolute position data output from the magnetic pole detection circuit 42 to the ROM 44 without any processing.
In this case, each UVW-phase stator coil of the brushless DC motor 11 is excited, and a magnetic flux is generated in each stator coil in a direction substantially orthogonal to the magnetic flux generated by the magnetic pole of the rotor. That is, the timing at which the phase difference α between the vector of the back electromotive force induced in the stator coil (back electromotive force vector) and the vector of the exciting current supplied to the stator coil (exciting current vector) becomes approximately 0 °. The stator coil is excited by. At this time, the linkage rate at which the magnetic flux generated by the stator coil and the magnetic flux generated by the rotor are linked becomes maximum. Therefore, the torque generated corresponding to the exciting current supplied to the stator coil is maximum,
It is possible to drive with an emphasis on acceleration.

On the other hand, when the cruise control mode is selected by pressing the cruise control switch, the cruise control signal e ₁ is input from the cruise control switch (not shown) to the main computer 29 to set the cruise traveling. Then, the main computer 29 performs phase control while searching for an optimum value (optimal phase difference) of the phase difference α that can maintain the vehicle speed at the time of setting and also keep the load current I at a minimum value. .. In this case, the load current I is brushless D
A phase current supplied to one of the UVW phases (for example, U phase) of the C motor 11 is detected, and therefore a Hall element is provided in the power supply line to the U phase. Then, the load current I is input to the main computer 29 as another signal e ₆ .

When the cruise control mode is selected by pressing the cruise control switch, the cruise travel is not set immediately, but the rotation speed R is set.
The cruise traveling can be set only when a predetermined condition is satisfied, such as a change in the accelerator opening or within a set range. In this way, the main computer 29 searches for the optimum value of the phase difference α while
Is used as the phase difference command signal p and CP of the resolver circuit 16
Output to U43.

FIG. 4 is a flow chart of a load current detection routine in a drive motor control device for an electric vehicle showing an embodiment of the present invention, and FIG. 5 is a cruise control routine in a drive motor control device for an electric vehicle showing an embodiment of the present invention. FIG. 6 is a flowchart of the optimum phase difference search routine in the drive motor control device for the electric vehicle showing the embodiment of the present invention. Step S1 In order to detect the load current I every set time, a timer is set and the timer value T is compared with the set value t ₁ . When the timer value T is smaller than the set value t _{1, the process} returns and stands by, and when the timer value T becomes larger than the set value t ₁ , the process proceeds to step S2. Step S2 The timer value T is set to 0. Step S3 The load current I is detected, and 1 is added to the count value N of the counter to make it N + 1. Step S4 The detection of the load current I is repeated 5 times, and when the count value N exceeds 5, the process proceeds to step S5. Step S5: Calculate the average value of the load current I detected five times in the past.

In this way, the main computer 29 always calculates the average value of the load current I. Next, the operation when the driver depresses the cruise control switch will be described. In this case, even if the cruise control switch is pressed, the cruise traveling is not set immediately, but the cruise traveling is set only when a predetermined condition is satisfied. Step S11: It is determined whether or not the driver depresses the cruise control switch. If it is not pressed, the process returns and waits, and if it is pressed, the process proceeds to step S12. In step S12, it is determined whether or not the change in the rotation speed R of the brushless DC motor 11 is within the set value. If it is not within the set value, the process returns and stands by, and if it is within the set value, the process proceeds to step S13. In step S13, it is determined whether the change in the accelerator opening is within the set value. If it is not within the set value, the routine returns and stands by, and if it is within the set value, it is determined that the conditions for setting cruise traveling are satisfied, and the process proceeds to step S14. In step S14, the optimum value of the phase difference α (optimum phase difference) is searched.

Next, the optimum phase difference search routine performed in step S14 will be described. Step S14-1 The value of the load current I is stored in the register A. Step S14-2 The value stored in the register A is stored in the register B. Step S14-3: Compare the value of register A with the value of register B. If the value of register A is less than the value of register B, proceed to step S14-4. If the value of register A is greater than the value of register B, It proceeds to step S14-7. Step S14-4: It is judged whether or not the value of the flag F is 0. If it is not 0, the procedure proceeds to step S14-5, and if it is 0, the procedure proceeds to step S14-6. Step S14-5 The value of the flag F is set to 0. Step S14-6 The value of the flag F is set to 1. Step S14-7: It is determined whether or not the value of the flag F is 0. If it is not 0, the procedure proceeds to step S14-8, and if it is 0, the procedure proceeds to step S14-10. Step S14-8: The phase difference α is shifted in the increasing direction by the set amount. In step S14-9, the value of the flag F is set to 1. Step S14-10: The phase difference α is shifted by a set amount in a decreasing direction. Step S14-11 The value of the flag F is set to 0.

When the cruise running is set, the main computer 29 searches for the optimum value of the phase difference α corresponding to the detected load current I, and the CPU 43 determines the phase difference α.
To the phase difference command signal p. FIG. 7 is a characteristic diagram of the drive motor in the drive motor control device for the electric vehicle of the present invention.

The figure shows the battery current, the rotational speed R, and the efficiency when two types of torque y ₁ and y ₂ are output and the phase difference α is changed. From the figure, it is understood that the battery current, the rotation speed R, and the efficiency are different depending on the values α ₁ , α ₂ , α ₃ , ... Of the phase difference α even when the same torque is output. In this case, the battery current is measured by ignoring what is consumed in other outfitting of the electric vehicle, and corresponds to the load current I.

As described above, the main computer 29
Searches for optimum values of the phase difference α (α ₁ and α _{2 in the} figure) so that the load current I becomes the minimum value. FIG. 8 is an explanatory diagram of digital absolute position data output from the CPU to the ROM in the embodiment of the present invention. As described above, the magnetic pole detection circuit 42 detects the absolute position of the induced magnetic poles of the rotor, and outputs C as 12-bit digital absolute position data.
Output to PU43. When the cruise running is set and the phase difference command signal p from the main computer 29 is received, the CPU 43 shifts the digital absolute position data by the phase difference α commanded by the phase difference command signal p. That is, virtual digital absolute position data is generated as if the absolute position shifted from the actual absolute position of the magnetic pole by the digital amount corresponding to the phase difference α in the rotational direction is detected, and the ROM 4 is used as the digital absolute position signal v.
Output to 4.

In this case, when the actual absolute position of the magnetic poles of the rotor changes in the range of 0 to 2π with the reference position being 0, the actual absolute position is digital as shown in the solid line in the normal running mode. It is output as absolute position data. Further, during cruise traveling, the phase difference command signal p is output from the main computer 29 to the CPU 43. When the phase difference α is commanded by the phase difference command signal p, the phase difference command signal p The digital absolute position data is shifted by a digital amount corresponding to α,
It becomes virtual digital absolute position data. The virtual digital absolute position data is stored in the ROM as a digital absolute position signal v.
It is output to 44.

FIG. 9 is an explanatory diagram of an analog signal output from the D / A converter of the embodiment of the present invention. In the figure, (a) shows the sine wave curve of the analog signal z output from the D / A converter 45 for the U phase. When the virtual digital absolute position data is output from the CPU 43 to the ROM 44 as the digital absolute position signal v, D
The phase of the sine wave curve of the analog signal z output from the / A converter 45 changes to be as shown in (b).

That is, when cruise running is set,
The main computer 29 searches for the optimum value of the phase difference α such that the load current I becomes the minimum value, and shifts the digital absolute position data of the magnetic poles of the rotor by the phase difference α. As a result, the stator coil is excited at such a timing that a phase difference α is formed between the back electromotive force vector induced in the stator coil and the exciting current vector.

As described above, in the drive motor control device for an electric vehicle having the above-described structure, the load current I is detected, the optimum value of the phase difference α that minimizes the load current I is searched, and the phase difference is calculated. Brushless DC motor 11 based on α
I am trying to drive. Therefore, the power consumption can be reduced extremely easily and reliably without requiring a large memory capacity.

Further, the phase difference α between the back electromotive force vector and the exciting current vector is changed by an electrical method, and the mechanical arrangement such as changing the position of the sensor for detecting the absolute position of the magnetic pole of the rotor is performed. The method is not adopted. Therefore, the time required to perform the motor control is short, and it is possible to suppress wear and wear caused by sliding parts. In particular, it is most suitable for an electric vehicle that is expected to travel on various road surfaces and is predicted to generate vibration, noise, and the like.

Further, since the resolver 15 having no electrical connection portion by contacting the parts is used to form the phase difference between the back electromotive force vector and the exciting current vector by a simple method, it is possible to cause a shock. It is strong and there are no restrictions due to operating temperature, noise, power supply voltage, etc. Further, in the above embodiment, the phase difference α between the back electromotive force vector and the exciting current vector can be continuously changed. Therefore, the driver selects the cruise running mode to reduce the phase difference α. By brushless DC motor 11
Can be driven.

In the first embodiment, the resolver 15 is used as a means for detecting the absolute position of the magnetic pole of the rotor. However, for example, an optical rotary encoder or a magnetic encoder (for example, Hall element or (Using a ferromagnetic thin film) can also be used. Furthermore, the phase difference α
In order to allow the driver to feel the change smoothly, a soft processing is performed so that the phase difference α by the phase difference command signal p from the main computer 29 does not become larger than a predetermined value per unit time. You can also In this process, the amount of change per unit time is suppressed so that the acceleration of the change in the phase difference α does not exceed a certain slope.

Further, the brushless DC motor 11 is
As shown in FIG. 3, it is arranged in each of the four drive wheels. For example, it is arranged on the vehicle body side instead of the engine of a vehicle using a conventional internal combustion engine, and is arranged via a differential device or the like. The drive wheels may be driven, and further, the engine and the brushless DC motor 11 may be combined and driven at the same time as the engine or at different times.

Further, in this embodiment, in the brushless DC motor 11, the phase difference α between the back electromotive force vector and the current command vector is electrically changed. The magnetic flux may be changed by controlling the magnetic current to change the interlinkage rate at which the magnetic flux of the rotor magnetic pole and the magnetic flux of the stator magnetic pole interlink. The flux linkage may be changed by changing the directional position.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a drive motor control device for an electric vehicle showing an embodiment of the present invention.

FIG. 2 is a detailed diagram of a drive motor control device for an electric vehicle showing an embodiment of the present invention.

FIG. 3 is a perspective view of an electric vehicle equipped with a drive motor control device according to an embodiment of the present invention.

FIG. 4 is a flowchart of a load current detection routine in the drive motor control device for the electric vehicle showing the embodiment of the present invention.

FIG. 5 is a flowchart of a cruise control routine in the drive motor control device for the electric vehicle showing the embodiment of the present invention.

FIG. 6 is a flowchart of an optimum phase difference search routine in the drive motor control device for the electric vehicle showing the embodiment of the present invention.

FIG. 7 is a characteristic diagram of a drive motor in the drive motor control device for an electric vehicle of the present invention.

FIG. 8 is an explanatory diagram of digital absolute position data output from a CPU to a ROM in the embodiment of the invention.

FIG. 9 is an explanatory diagram of an analog signal output from the D / A converter according to the embodiment of this invention.

[Explanation of symbols]

 11 Brush DC Motor (Drive Motor) 12 DC Power Supply 13 Rotor Shaft 15 Resolver 16 Resolver Circuit 17 Current Waveform Control Circuit 18 Bridge Circuit 21-26 Power Transistor 28 Base Driver Circuit 29 Main Computer 33 Power Supply Circuit 34 Capacitor 35 Current Sensor 43 CPU

Claims (1)

[Claims] 1. A drive motor control device for an electric vehicle that travels by generating at least part of a driving force of a vehicle by a drive motor including a stator and a rotor, wherein: (a) a magnetic flux generated by a magnetic pole of the stator and the rotor; (C) means for detecting the load current of the drive motor, and (c) control for minimizing the detected load current. A drive motor control device for an electric vehicle, comprising: means for searching a quantity; and (d) means for outputting the searched control quantity to the interlinkage ratio changing means.