JP4032516B2 - Electric drive for automobile - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric drive device for an automobile for generating driving power for an electric vehicle or a hybrid electric vehicle.
[0002]
[Prior art]
An electric drive device for automobiles used in conventional electric vehicles and hybrid electric vehicles includes a traveling motor composed of a three-phase AC motor, and a three-phase inverter circuit (simply supplying DC power to the traveling motor by converting DC power) An inverter circuit) and a controller for intermittently controlling the inverter circuit. As this three-phase AC motor, a magnet-type synchronous motor, a so-called brushless DC motor is employed.
[0003]
[Problems to be solved by the invention]
However, electric vehicle travel motors are required to have higher reliability in order to ensure safety during operation, and higher driving efficiency is required to reduce power consumption. Unlike the engine-type car, it does not have a high-noise engine, so it has been required to be quieter.
[0004]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an automobile electric drive device excellent in safety, driving efficiency, and quietness.
[0005]
[Means for Solving the Problems]
According to the electric drive device for an automobile according to claim 1, a magnet type synchronous motor (so-called brushless DC motor) having a plurality of three-phase windings is used as a traveling motor of the electric vehicle.
More specifically, the present invention relates to a rotor having a plurality of pairs of magnetic poles alternately arranged at equal intervals in the circumferential direction, and a plurality of three phases arranged on the circumference separated by a predetermined phase difference in electrical angle. A travel motor having a stator coil with windings, and a control device for supplying a three-phase alternating current separated by the phase difference to each phase winding of the stator coil,
The stator coil has two three-phase windings arranged on the circumference with a phase difference of π / 6 or π / 3 radians in electrical angle and having independent neutral points, Is a motor-driven electric drive device for an automobile that supplies a three-phase alternating current having a phase difference of π / 6 or π / 3 radians in electrical angle to the three-phase windings, wherein the control device is fed from the same DC power source. A pair of inverter circuits that individually supply the three-phase alternating current to the three-phase windings, and a vector sum of the currents of the respective one-phase currents having a small phase difference between the three-phase windings. A pair of current sensors, a rotation sensor for detecting the rotational position of the rotor, and a d-axis current detection value Id and a q-axis current detection value Iq calculated based on the vector sum and rotation position of the detected pair of currents. Based on the voltage finger for both three-phase winding A controller that intermittently controls each switching element of the pair of inverter circuits by calculating a value and outputting the calculated voltage command values for the three-phase windings to the inverter circuits. It is said.
In this way, the following effects can be obtained.
[0006]
First, in a conventional three-phase AC motor (three-phase brushless DC motor), one of the phase windings of the stator coil or one of the phase inverters of the inverter circuit (a circuit unit that generates one phase current) during traveling. If one of them fails, torque is generated, but the generated torque in the two-phase operation mode is weak, noise increases due to the effects of the unbalanced rotating magnetic field, efficiency decreases, and furthermore, it stops at an intersection, etc. Since the starting torque is 0 or very small, there is a problem that there is a high possibility that the vehicle will almost fail to re-run.
[0007]
On the other hand, in this configuration, since the stator coil has a plurality of three-phase windings, one of the phase windings of the stator coil or one of the phase inverters of the inverter circuit (one phase current is generated during traveling). If one of the circuit parts) fails, the remaining three phase currents can be supplied normally, so that a smooth rotating current magnetic field can be formed, and the reduction in generated torque can be easily covered by the increased burden on the remaining phase windings. It can be suppressed to a possible level, noise increase and efficiency reduction can also be suppressed, and furthermore, even if it stops at an intersection etc., a sufficiently large starting torque can be secured in practice, and it is excellent as a traveling motor for electric vehicles The suitability for use can be ensured.
[0008]
Although the number of phase windings and the number of phase inverters in the inverter circuit are increased by using a brushless DC motor having a plurality of three-phase windings, if the motor's rated output is the same, the phase winding or phase Since the amount of current per inverter is reduced, the above advantages can be obtained without causing a significant increase in device cost.
[0009]
In addition, the rotational current magnetic field formed by the current is more smoothly changed (sinusoidal) even during normal operation where the above-mentioned abnormality does not occur, so that the effect of greatly reducing harmonic electromagnetic noise that generates annoying noise can also be achieved. You can expect.
According to the present invention, the stator coil is composed of two independent three-phase windings having a phase difference of π / 6 or π / 3.
[0010]
Thus, it is possible to further exhibit the following advantages in addition to the work for the above-described effect.
First, since the stator coils are composed of completely independent three-phase windings (three-phase armature windings), only one of the three-phase windings is operated and the other three-phase winding is not operated. Furthermore, in this case, the possibility of unnecessary current flowing from the operating three-phase winding to the resting three-phase winding (for example, through the diode of the inverter circuit) can be completely prevented, and safety can be prevented. And unnecessary power loss and heat generation can be reduced.
[0011]
Also, in a brushless DC motor, it is essential to detect the current of each phase winding, that is, each phase current. However, if the neutral point of each of these three-phase windings is short-circuited to obtain 6-phase current, While at least five current sensors are required to determine accurately, in this configuration, the three-phase windings are independent of each other, so that all phase currents can be accurately determined by providing two current sensors. Therefore, accurate current detection can be performed while reducing the required number of expensive current sensors.
[0012]
In a preferred embodiment, a full-phase winding power feeding mode for feeding both three-phase windings and a half-phase winding feeding mode for feeding only one of the three-phase windings are switched.
In this way, for example, when the traveling load is large, the low-noise and high-efficiency operation can be performed by the all-phase winding power supply mode. As a result, the switching loss can be reduced. Note that most of the loss of the switching element of the inverter circuit is mainly constituted by the switching loss that occurs during the transition period from on to off of the switching element and from off to on, and due to the reduction in the number of switching of the switching element of the inverter circuit. This switching loss can be reduced.
[0013]
In a preferred embodiment, if an abnormality in one of the outputs of both three-phase windings is caused by a disconnection of the phase windings or a fault in the phase inverter of the inverter circuit that supplies phase current thereto, this is detected and the other normal Execute half-phase winding power supply mode operation with three-phase winding.
In this way, even when the output is abnormal, the symmetry of the rotating current magnetic field is improved as compared with the case where only one of the all-phase windings is turned off, so that the efficiency can be improved and the noise can be reduced.
[0014]
In a preferred embodiment, when the running load is lighter than a predetermined value, the half-phase winding power supply mode operation is executed by the other normal three-phase winding.
In this case, the symmetry of the rotating current magnetic field is improved as compared with the case where only one of the all-phase windings is turned off. Therefore, the efficiency is improved and the noise is reduced particularly at an output of less than 50% of the rated output. be able to.
[0015]
According to the present invention, the control device includes a pair of inverter circuits that are supplied with power from the same DC power source and individually supply the three-phase AC current to both three-phase windings, and one controller that intermittently controls the inverter circuit. And have.
In this way, since the controller can be shared by both inverter circuits, the circuit configuration can be simplified.
[0017]
According to the present invention, each phase current of both three-phase windings is estimated based on a pair of combined currents that are vector sums of the phase currents flowing through each one of the three-phase windings.
Thus, expensive current sensor despite substantially using two three-phase windings can be dispensed with two, while simplifying the circuit configuration, to detect both winding current Therefore, it becomes easy to detect a failure such as a short circuit.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the electric drive apparatus for automobiles of the present invention will be described with reference to the following examples.
[0019]
[ Reference Example 1]
A reference example of the automobile electric drive device of the present invention will be described below with reference to FIG. FIG. 1 is a circuit diagram of the automobile electric drive apparatus.
Reference numeral 1 denotes a brushless DC motor used as a travel motor of an electric vehicle. A stator 11 has two three-phase windings 111 wound with an electrical angle and a spatial phase difference of π / 6 to π / 3 radians apart. 112, and each of the three-phase windings 111 and 112 has a three-phase phase winding wound with an electrical angle and a spatial phase difference of 2π / 3 radians apart from each other. 12 is a rotor and 13 is a resolver.
[0020]
Reference numeral 2 denotes a control device that feeds a three-phase alternating current having a phase difference of π / 6 or π / 3 to the three-phase windings 111 and 112, and a semiconductor switching bridge circuit using a power switching element such as an IGBT. (Three-phase inverter circuits) 21 and 22 and a computer (controller) 23 for determining a current value corresponding to a required torque specified by an accelerator signal of the electric vehicle. Reference numeral 24 denotes a capacitor that absorbs switching noise, reference numerals 25 and 25 ′ denote current sensors that detect phase currents of two phases of the three-phase windings 111 and 112, and reference numeral 3 denotes a battery for storing traveling power. In the semiconductor switching bridge circuits (three-phase inverter circuits) 21 and 22, it is normal to connect a diode in antiparallel with each power switching element, but the illustration is omitted.
[0021]
2 and 3 are winding diagrams of the brushless DC motor of this reference example, and FIG. 4 is a winding diagram of a conventional three-phase brushless DC motor.
First, the windings of a conventional three-phase motor will be described with reference to FIG. 4. Reference numerals 121 and 122 denote magnetic poles made of permanent magnets of the rotor 12, which have different polarities and are arranged in pairs. . 113 is an iron core tooth of the stator 11, and 114 is an iron core slot of the stator 11. In the case of a three-phase motor, the total number of turns is generally three times the number of magnetic poles and the number of slots. 111X, 111Y, and 111Z are three-phase windings wound around the slot 114 with an electrical angle of 2π / 3 radians.
[0022]
On the other hand, as shown in FIG. 2, the brushless DC motor of this reference example has 2 × 3 times the number of magnetic poles and the number of slots, and the slot pitch is π / 6 radians in electrical angle. ing. 111X, 111Y, and 111Z are phase windings of the first three-phase winding 111 wound at one magnetic pole pitch (all nodes), and 112X, 112Y, and 112Z are relative to the first three-phase winding 111. Each phase winding of the second three-phase winding 112 is wound in full pitch with an electrical angle phase difference of π / 6 radians.
[0023]
FIG. 3 shows a winding example having two three-phase windings when the electrical angle phase difference is 2π / 3 short-winding with respect to the magnetic pole pitch, and the two three-phase windings are π / 3. The electrical angle phase difference is as follows.
The computer 23 outputs to the semiconductor switching bridge circuit (three-phase inverter circuit) 21 based on the current value from the current sensor 25 ′ that detects the two phase currents of the three-phase winding 111 and the rotation angle obtained by the resolver 13. The signal voltage (voltage command value) is determined, and similarly, based on the current value from the current sensor 25 that detects the two phase currents of the three-phase winding 111 and the rotation angle obtained by the resolver 13, the semiconductor switching bridge circuit (three The signal voltage (voltage command value) to be output to the phase inverter circuit) 22 is determined.
[0024]
The semiconductor switching bridge circuit (three-phase inverter circuit) 21 supplies the first three-phase alternating current to the three-phase winding 111 based on the signal voltage from the computer 23, and the semiconductor switching bridge circuit (three-phase inverter circuit). ) 22 supplies the three-phase winding 112 with the second three-phase alternating current having the electrical angle phase difference with respect to the first three-phase alternating current.
[0025]
Next, in the case of the conventional winding shown in FIG. 4, the effect obtained when the three-phase current having the electrical angle phase difference is independently fed to the stator 11 having the two three-phase windings 111 and 112 described above. As an example, the case of a full volume winding having a π / 6 phase difference as compared with FIG.
5 to 8 show temporal changes in the resultant magnetomotive force due to the three-phase alternating current in the case of a conventional all-node three-phase winding. FIGS. 9 to 12 show two three-phase windings having a π / 6 phase difference. A change in the resultant magnetomotive force when a three-phase alternating current having a π / 6 phase difference is supplied to the stator 11 having the phase windings 111 and 112 is shown.
[0026]
In the conventional three-phase winding shown in FIG. 4, the combined magnetomotive force generated by the three-phase winding changes with the passage of time t1, t2, and t3, whereas in this embodiment, two three-phase windings 111, It was found that the synthetic magnetomotive force produced by 112 does not change at t1, t2, and t3, and therefore the electromagnetic force with the rotor 12 does not change with rotation, so that the electromagnetic noise can be significantly reduced as compared with the prior art.
[0027]
[ Reference Example 2]
Another reference example of the automobile electric drive device of the present invention will be described with reference to FIG. FIG. 13 is a block diagram for explaining another control method in the automobile electric drive device. In this reference example, energization of the three-phase windings 111 and 112 is performed using well-known vector control. Note that the conventional control method, that is, vector control for energizing a single three-phase winding, is performed only in a portion 1000 surrounded by a broken line in FIG.
[0028]
The U-phase current and W-phase current of the three-phase winding 111 of the motor 1 are detected by current sensors 251 and 251, and the rotor rotation angle of the motor 1 is detected by the resolver 13 with reference to the three-phase winding 111. This measured current value is converted into d- and q-axis currents by the three-phase / two-phase conversion circuit 1002 based on the rotational position, and current control of each of d and q is performed by the current control circuits 1004 and 1006 based on this current and the current command. Do. The current control is performed by feedback control or feedback + feedforward control based on the command value and the actual measurement value, but the description is omitted because it is not the gist of this embodiment. Then, the obtained d and q-axis voltage command values are converted into U, V, and W phase voltage command values by two-phase and three-phase conversion by a two-phase and three-phase conversion circuit 1008, and the three-phase winding 111 is connected through an inverter 1010. To drive.
[0029]
Further, the three-phase winding 112 adds the phase difference Δθ between the two windings 111 and 112 to the rotation angle detected by the resolver 13 by the adding unit 1022, and the two-phase three-phase conversion circuit 1020 adds the phase difference Δθ based on the added value. Two-phase to three-phase conversion is performed, and the obtained U, V, and W phase voltage command values are driven through the inverter 22 to the three-phase winding 111. The U, V, and W voltage commands of the winding 112 are calculated, and the inverter 1024 is used to drive the three-phase winding 112.
[0030]
According to this method, the current sensors 25 and 25 for the three-phase winding 112 can be omitted.
[0031]
[ Example 1 ]
Example 1 of an automotive electric drive system of the present invention with reference to FIG. 14 will be described. FIG. 14 is a block diagram illustrating a control method in the automobile electric drive device of the present invention. In this embodiment, energization of the three-phase windings 111 and 112 is performed using well-known vector control. In this embodiment, in the shown to vector control in FIG. 13 is obtained by changing the arrangement of the current sensor 1030, 1032.
[0032]
In this embodiment, the vector sum of the U-phase currents of the three-phase windings 111 and 112 is detected by the current sensor 1030, and the vector sum of the W-phase currents of the three-phase windings 111 and 112 is detected by the current sensor 1032. The resolver 13 detects the rotor rotation angle based on the phase winding 111. Three-phase two-phase conversion is performed from the rotation angle and the total current value by the three-phase two-phase conversion circuit 1002 to calculate temporary d and q axis phase currents. Next, from the d and q axis currents and the spatial phase difference Δθ between the two three-phase windings 111 and 112, the current of the winding 111 is calculated by the calculation unit 1034 based on the following equation. Hereinafter, the control method is the same as that of the second embodiment.
[0033]
1d1 = 1d / (2 × cos (Δθ / 2))
1q1 = 1q / (2 × cos (Δθ / 2))
In the above-described embodiment, the position of the resolver 13 is set with reference to the winding 111, but a change such as setting an intermediate position between the winding 111 and the winding 112 as a reference is naturally possible.
[0034]
According to each of the above-described embodiments, electromagnetic noise can be reduced in principle. Therefore, even when the switching frequency of the control device is lowered from 10 KHz to 5 KHz or less compared with the conventional electric drive device for automobiles, the high frequency electromagnetic wave is annoying. Sound is not generated, and there is an effect that switching loss can be reduced to ½ or less of the conventional one.
[0035]
[ Example 2 ]
In the case of driving with only one winding, only the current command value of the winding to be driven may be controlled based on the phase difference. For example, even if one of the windings 111 and 112 fails or one of the two inverters 1010 and 1024 becomes defective, normal three-phase AC drive can be performed with one normal combination, and the maximum torque is reduced. Only partial load operation does not cause any trouble in running.
[0036]
A flowchart executed in this case by the computer 23 will be described with reference to FIG.
First, the accelerator opening is input (S100), and it is checked whether the accelerator opening is much smaller for the predetermined period immediately before and is still smaller (S102). If not, the process proceeds to S104.
[0037]
In S104, the current command value is caused by one of the currents of the three-phase windings 111 and 112, for example, when one of the windings 111 and 112 fails or one of the two inverters 1010 and 1024 becomes defective. In step S102, it is checked whether or not it has been out of the predetermined period immediately before and at present (S102). If not, power is supplied to the two three-phase windings 111 and 112 (S106).
[0038]
On the other hand, in S102, if the accelerator opening is not small for the predetermined period immediately before or is currently large (S102), the process proceeds to S108.
Similarly, in S104, if one of the currents of the three-phase windings 111 and 112 has been out of the predetermined period immediately before the current command value and is still out of the current period, the normal three-phase winding is replaced. Only power is supplied (S108).
[0039]
In this way, it is possible to reduce power loss at the time of a small traveling load, and to generate traveling power with low noise and high efficiency even when the abnormality occurs.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an automotive electric drive device of a reference example.
FIG. 2 is a winding diagram of the brushless DC motor of FIG. 1;
FIG. 3 is a winding diagram of the brushless DC motor of FIG. 1;
FIG. 4 is a winding diagram of a conventional brushless DC motor.
FIG. 5 is a timing chart showing temporal changes in the magnetomotive force of each phase due to a three-phase alternating current in the case of a conventional full-phase three-phase winding.
6 is a timing chart showing temporal changes in the resultant magnetomotive force due to a three-phase alternating current in the case of the conventional full-node three-phase winding shown in FIG.
7 is a timing chart showing temporal changes in the resultant magnetomotive force due to a three-phase alternating current in the case of the conventional full-phase three-phase winding shown in FIG.
8 is a timing chart showing temporal changes in the resultant magnetomotive force due to a three-phase alternating current in the case of the conventional full-phase three-phase winding shown in FIG.
FIG. 9 is a timing chart showing temporal changes of each phase magnetomotive force due to a three-phase alternating current of a reference example.
10 is a timing chart showing temporal changes in the resultant magnetomotive force due to a three-phase alternating current in the case of the conventional full-phase three-phase winding shown in FIG.
11 is a timing chart showing temporal changes in the resultant magnetomotive force due to a three-phase alternating current in the case of the conventional full-phase three-phase winding shown in FIG. 9; FIG.
12 is a timing chart showing temporal changes in the resultant magnetomotive force due to a three-phase alternating current in the case of the conventional full-node three-phase winding shown in FIG.
FIG. 13 is a block diagram illustrating a control method of a reference example of the electric drive device for an automobile according to the present invention.
FIG. 14 is a block diagram for explaining a control method of the embodiment of the electric drive apparatus for an automobile of the present invention.
FIG. 15 is a flowchart showing a control operation of another embodiment of the electric drive apparatus for an automobile of the present invention.
[Explanation of symbols]
1 is a brushless DC motor (travel motor), 2 is a control device, 11 is a stator, 12 is a rotor, 13 is a resolver, 25 and 25 'are current sensors, 111 and 112 are three-phase windings, and 21 and 22 are semiconductor switching devices Bridge circuit (inverter circuit), 23 is a computer (controller), S106, S108 are power supply mode switching means

Claims (1)

Traveling with a rotor having a plurality of pairs of magnetic poles alternately arranged at equal intervals in the circumferential direction, and a stator coil having a plurality of three-phase windings arranged on the circumference separated by a predetermined phase difference in electrical angle A motor, and a control device for supplying a three-phase alternating current separated by the phase difference to each phase winding of the stator coil ,
The stator coil has two three-phase windings arranged on the circumference with a phase difference of π / 6 or π / 3 radians in electrical angle and independent of neutral points,
In the electric drive device for an automobile, the control device supplies a three-phase alternating current having a phase difference of π / 6 or π / 3 radians in electrical angle to both the three-phase windings.
The controller is
A pair of inverter circuits that are fed from the same DC power source and individually supply the three-phase AC current to the three-phase windings;
A pair of current sensors for detecting a vector sum of currents of each phase with a small phase difference between the three-phase windings,
A rotation sensor for detecting a rotation position of the rotor;
Based on the detected vector sum of the pair of currents and the rotational position, the d-axis current detection value Id and the q-axis current detection value Iq are calculated to calculate the voltage command values for the three-phase windings. One controller for intermittently controlling each switching element of the pair of inverter circuits by outputting voltage command values for the three-phase windings to the two inverter circuits;
An automobile electric drive device comprising:

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