JP3218907B2 - Electric car - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle, and more particularly to an improved electric vehicle for improving charging efficiency and safety when using power conversion means for performing bidirectional AC / DC power conversion.

[0002]

2. Description of the Related Art An electric vehicle uses a synchronous motor as a prime mover and a running storage battery as a power source. Considering the convenience of charging the storage battery for traveling, it is desirable to install a charging device on the electric vehicle,
A new dedicated charging device increases the weight load on the electric vehicle. In recent years, a dedicated charging device is mounted by sharing the inverter for driving the motor during driving as a PWM converter during charging. As a result, the weight load on the electric vehicle is reduced. This configuration is disclosed in JP-A-59-61402, JP-A-5-207664, and the like. Japanese Patent Laid-Open No. Hei 5-207664 discloses a configuration in which one phase of an AC motor is used as a chopper coil during charging.

[0003]

When a field coil wound on a stator is used as a chopper coil, in an induction motor in which a magnetic pole is formed at a position corresponding to a magnetic field line created by the field coil, the current is simply supplied to the field coil. By doing so, the magnetic field produced is directed only in one direction and no circumferential force is generated between the rotor and the stator, so that there is no particular problem. However, in synchronous motors such as a permanent magnet type synchronous motor having a permanent magnet on a surface facing the stator or a reluctance type synchronous motor having a salient pole in a convex shape protruding toward the stator on a surface facing the stator, Due to the positional relationship between the permanent magnets or salient poles and the position of the magnetic poles on the stator created by the field coil when the field coil is energized, the synchronous motor rotates slightly but does not have a clutch. There was a problem of moving. In other words, there is no problem if the magnetic pole created by the field coil and the magnetic pole on the rotor side are balanced at the time of charging, that is, if the combined magnetic field created by both is oriented in the radial direction,
If the electric angle between the magnetic pole on the stator side and the magnetic pole on the rotor side when current flows through the field coil for use as a chopper coil deviates, the rotor will rotate by the deviated amount to be in a state of equilibrium. Therefore, the synchronous motor rotates. Therefore, when a field coil is used as a chopper coil in a synchronous motor, it is necessary to consider the above phenomenon during charging.

[0004] The present invention has been made to solve the above problems, and an object of the present invention is to prevent a synchronous motor, which is a running motor of an electric vehicle, from rotating during charging.

[0005]

In order to achieve the above object, an electric vehicle according to the present invention comprises a stator having a field coil wound thereon and a permanent magnet or salient pole provided on a surface facing the stator. Motor, a switching element pair having the number of phases of a field coil of the synchronous motor, and a flywheel diode connected in parallel with the switching element in a reverse current direction. A power conversion unit having an output terminal as a connection part of the pair connected to an input terminal of the synchronous motor, and a traveling unit having both positive and negative electrodes connected to input terminals at both ends of each switching element pair of the power conversion unit. By controlling the energization timing of the storage battery and the switching element of the power converter, the DC power input to the input terminal of the power converter is converted to AC. A controller that converts the output from the output terminal or converts the AC power input to the output terminal of the power conversion means into DC and outputs the DC power from the input terminal. Switching means for inserting and connecting an external AC power supply to a system of one phase of the power conversion means and the field coil of the synchronous motor; and electrical angle detection means for detecting an electrical angle of the rotor; Controlling the AC power from the external AC power supply by controlling the energization timing of the switching element when charging the traveling storage battery, and detecting the direction of the magnetic field formed by the field coils of each phase by the electrical angle detection. It is characterized in that it is adapted to the direction of the electrical angle of the rotor detected by the means.

[0006]

According to the electric vehicle of the present invention having the above-described configuration, the direction of the electric angle of the rotor is detected by the electric angle detecting means during charging. The direction of the magnetic field formed in the field coil is adjusted to match the direction of the detected electrical angle of the rotor. That is, the controller controls the AC power output from the electric conversion means to the field coil based on the direction of the electrical angle of the rotor, thereby causing a desired current to flow through the field coil. As a result, even if the field coil is used as a chopper coil, the direction of the magnetic field formed in the field coil can be made to coincide with the direction of the electrical angle of the rotor, so that the rotation of the synchronous motor during charging is ensured. Can be prevented.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is an overall configuration diagram showing a first embodiment of an electric vehicle according to the present invention. In FIG. 1, an electric vehicle 1 according to the present embodiment includes a synchronous motor 2 having a stator on which a field coil is wound, a rotor having a permanent magnet provided on a surface facing the stator, and each switching of a power converter 6. A traveling storage battery 4 having both positive and negative electrodes connected to input terminals at both ends of the element pair, a switching element pair having the number of phases of the field coil of the synchronous motor 2, and a current direction opposite to the switching element in parallel with the switching element. A power converter 6 as a power conversion means having a flywheel diode connected thereto and an output terminal serving as a connection part of each switching element pair connected to an input terminal of the synchronous motor 2, and a switching element of the power converter 6 , The DC power input to the input terminal of the power converter 6 is converted into AC and output from the output terminal, or the power converter 6 A controller 8 for converting AC power input to the output terminal into DC and outputting the DC power from the input terminal, an electrolytic capacitor 9 for smoothing a current flowing through the storage battery 4, and an external AC when charging the storage battery A switch unit 12 as switching means for inserting and connecting a power supply to the power converter 6 and one phase system of the field coil of the synchronous motor 2;
have. In this embodiment, the external AC power supply 10 uses 100/200 V, 50/60 Hz single-phase AC.
The power converter 6 serves as a motor drive inverter for driving the synchronous motor 2 by converting DC from the traveling storage battery 4 to AC during traveling, and converts DC to DC during charging to drive the synchronous storage battery 4. It operates as a PWM converter for charging the battery.

Further, the electric vehicle 1 has AC current sensors 14a and 14b for detecting an AC current, a DC voltage sensor 16 for detecting a DC voltage, a DC current sensor 18 for detecting a DC current, and a synchronous motor. 2 has an electric angle detection sensor 20 as an electric angle detecting means for detecting an electric angle of the rotor, and is connected to the controller 8. The electric angle detection sensor 20 shares a sensor used when the synchronous motor is driven.

FIG. 2 is a connection diagram of main parts of the electric vehicle in FIG. As is apparent from FIG. 2, one end of one phase of the three-phase star connection is connected to the external AC power supply 10 of the synchronous motor 2 via the switch unit 12, and the other two phases are connected to the AC current sensors 14a and 14b. The power converter 6 is connected via the power converter 6. Since the terminals of each phase appear outside, they can be easily connected to the respective components.

A characteristic of this embodiment is that when the controller 8 performs chopper control and starts charging the traveling storage battery 4, the controller 8 detects the electrical angle of the rotor before applying a current to a field coil used as a chopper coil. Then, according to the angle, the direction of the magnetic field of the field coil is adjusted so that the field coil and the permanent magnet just attract or repel, that is, balance. That is, the controller 8 controls the energization timing of the switching element of the power converter 6 to control the AC power from the external AC power supply 10 so that a desired current can flow through the field coil. By controlling the electric angle of the magnetic field lines of the field coil to coincide with the electric angle of the magnetic field lines of the permanent magnet, the rotation of the rotor can be prevented.

The operation of this embodiment will be described below.

First, when the electric vehicle is running, it is disconnected from the external AC power supply 10, so that the switch section 12 is closed, and the synchronous motor 2 functions as a motor. The power converter 6 functions as a motor driving inverter. The operation at the time of traveling is the same as the conventional operation, and therefore the description is omitted.

When the electric vehicle is charged, the switch section 12 is switched to connect the external AC power supply 10 to the synchronous motor 2 and the power converter 6. As described above, the present invention is characterized in that the rotation of the rotor, which may occur when a current flows through the field coil, is prevented by adjusting the direction of the magnetic field of the field coil. Hereinafter, this control will be described.

FIG. 3 is an equivalent circuit diagram of a main part in the configuration shown in FIG. In this embodiment, the W-phase is connected to the external AC power supply 10, the U-phase is a field coil through which the current i1 flows, and the V-phase is through the current i2. Also, v1 and v2 are currents i1 and i2 from the power converter 6.
Are voltages output to the field coils that flow.
In this configuration, in the present embodiment, the rotor i is attracted to the magnetic field generated by the current by independently adjusting the currents i1 and i2 obtained by dividing the current i input from the external AC power supply 10 into the remaining two phases. Then, the magnetic poles on the stator side formed by the field coils are balanced with the permanent magnets of the rotor. The currents i1 and i2 are adjusted by the controller 8 that controls the power converter 6 that functions as a PWM converter during charging.

First, in FIG. 2, e = Ldi / dt + Ldi1 / dt + v1 (1) e = Ldi / dt + Ldi2 / dt + v2 (2) Here, L is the inductance of each field coil. The magnetic field generated by the three-phase synchronous motor including the induction motor can be represented by the following equation (3).

Ф = {iucosφ + ivcos (φ−3π / 2) + iwcos (φ + 3π / 2)} × L (3) That is, the magnetic field at the position where the permanent magnet is rotated by the angle φ shown in FIG. Can be obtained by Expression (3).

Here, the following equations (4) can be obtained from FIG. 2 and FIG. 4 (a). iu = i = Isinθ iv = −i1 = −I1sinθ iw = −i2 = −I2sinθ I = I1 + I2 (4) where θ (= ωt) is the phase angle of the external AC power supply 10.

From equations (3) and (4), Ф = {(3/2) · I sin θ cos φ− (SQRT (3) / 2) · (I1-I 2) sin θ sin φ｝ × L = (3/2) · SQRT (1+ (I1-I2) 2 / 3I2) × Isin θ cos (φ−α) × L (5) Here, SQRT () represents a square root. It should be noted that the condition shown in equation (4) is for the P
This is a case where a WM converter is used. Where α
Is the angle of the magnetic field formed by the field coil, and α = tan−1 (− (I1−I2) / (SQRT (3) · I)) (6) What is expressed by Expression (5) is Ｋ = Kcos (φ−α) (K is a constant), that is, the direction of Ф is advanced by the angle α. This relationship is shown in FIG. In the case of an induction motor having no permanent magnet, it can be handled as φ = 0.

The angle φ of the magnetic field formed by the permanent magnet can be detected by the electric angle detection sensor 20. Therefore, as shown in FIG.
The controller 8 controls the power converter 6 and adjusts the currents i1 and i2 independently so that the angle φ of the magnetic field a and the angle α of the magnetic field formed by the field coil 2b are independently adjusted. And the permanent magnet can be balanced. As a result, generation of torque of the synchronous motor 2 can be prevented, and a motor lock (brake) by magnetism can be applied.

From the equations (4) and (6), I1 = IＩ (1-SQRT (3)） tanα) / 2 (7) I2 = I ・ (1 + SQRT (3) ・ tanα) / 2 ( 8) Therefore, the controller 8 calculates i1 = I1 sin θ = I · (1−SQRT (3) · ta
nα) · sin θ / 2 i2 = I2 sin θ = I · (1 + SQRT (3) · ta
It is sufficient to adjust the currents i1 and i2 so that nα) · sin θ / 2. By transforming the equations (1) and (2), di1 / dt = {e- (2v1-v2)} / 3L (9) di2 / dt = {e- (2v2-v1)} / 3L (10 ), The controller 8 can arbitrarily control the currents i1 and i2 by causing the power converter 6 to set the desired voltages v1 and v2.

Thus, according to the present embodiment, the inductance of the synchronous motor 2 itself is used to
If 90 ° <α <90 °, even when the field coil is used as the chopper coil, the electric motor can be reliably prevented from moving during charging without rotating the synchronous motor 2. Needless to say, angles other than the above can be handled by switching the handling of each phase.

By the way, in this embodiment, the above-described configuration not only prevents the synchronous motor 2 from rotating without using an active filter, a reactor or the like as a dedicated charging device, but also a power factor that does not cause harmonic interference. 1 can be realized. This is because, when the above equations (9) and (10) are added, d (i1 + i2) / dt = di / dt = {2e- (v1 + v2)} / 3L. From this equation, if the voltages v1 and v2 are controlled by PWM control and the power supply voltage is considered, di /
dt can be arbitrarily controlled. Therefore, the input current i can be made into a sine wave, and as a result, if the phase is made the same as the phase of the power supply voltage, the power factor 1 can be controlled. The power supply voltage, that is, the phase of the external AC power supply 10 can be easily obtained by a detector or calculation.

This calculation is performed as follows. At the time of charging, the output power of the power converter 6, in this case, the PWM converter, is calculated based on information from the DC voltage sensor 16 and the DC current sensor 18. When the input power factor of the PWM converter decreases, the output power also decreases. Therefore, the phase difference φ between the power supply voltage and the input current can be estimated and calculated from the relationship (the following equation) between the output power and the apparent power calculated from the detected value of the input current.

Cos φ = (PWM converter efficiency) ×
(Output power) / (Input apparent power) The delay of the phase can be determined by focusing on the instantaneous power. For example, assuming that the integral sum of the instantaneous power of the phase −π / 2 to 0 of the input current is Pa and the integral sum of the instantaneous power of the phase 0 to π / 2 is Pb, when Pa> Pb, the input with respect to the power supply voltage is obtained. It can be seen that the current is advanced, and vice versa.

The determination at 50/60 Hz can also be made by focusing on the instantaneous power. That is, assuming that the integral sum of the instantaneous powers of the input current phases 2π to 5π / 2 is Pc, Pc
If there is a significant difference between b and Pc, it is understood that the frequency information is wrong.

Next, the algorithm of the controller 8 operated as described above will be described.

FIG. 5 shows a converter P when the controller 8 controls the power converter 6 as a PWM converter.
FIG. 4 is a control block diagram illustrating a WM algorithm. A power factor of 1 is realized by the input current loop of this algorithm, and since the DC voltage is fed back in FIG. 5A, it is possible to control the DC voltage to be constant, and in FIG. It is possible to control the current of the traveling storage battery 4 to be constant by the method. FIG. 5 (c) is the same as FIG.
It is the figure which showed the common part in (a) and (b).

FIG. 6 is a diagram showing details based on the control law of the converter PWM algorithm. FIG.
3A is a diagram based on an algorithm for preventing rotation of the rotor, and shows ON / O of a transistor for controlling output terminals A and B of the power converter 6 in FIG.
It is a figure showing FF. FIG. 6B is a diagram based on an algorithm for realizing a power factor of 1, and FIG.
FIG. 4 is a diagram showing ON / OFF of a transistor for controlling an output terminal C of the power converter 6 in FIG.

As described above, according to the present embodiment, even if a field coil is used as a chopper coil in a permanent magnet type synchronous motor, the electrical angle of the rotor and the electrical angle of the magnetic pole formed by the field coil are determined. Since the control can be performed so as to match, the synchronous motor 2 can be reliably locked without rotating the synchronous motor 2 during charging.

When a commercial power supply is used as an input power supply for charging, a power factor of 1 cannot be realized unless an active filter, a reactor or the like is used as a dedicated charging device. According to the configuration, since the power factor of 1 can be realized without using a dedicated charging device, the vehicle weight and the space can be further reduced.

As described above, in the present embodiment, a permanent magnet type synchronous motor is used as a synchronous motor. However, the present invention can be similarly applied to an electric vehicle using a reluctance type synchronous motor.

Embodiment 2 FIG. 7 is an overall configuration diagram showing a second embodiment of the electric vehicle according to the present invention, FIG. 8 is a connection diagram of main parts of the electric vehicle in FIG. 7, and FIG. It is an equivalent circuit diagram of a part. The same elements as those in the first embodiment are denoted by the same reference numerals.

In the first embodiment, the switching means for inserting and connecting the external AC power supply 10 to the power converter 6 and the one-phase system of the field coil of the synchronous motor 2 when charging the traveling storage battery is shown in FIG. Although a mechanically switched relay is used as shown in FIG. 2, the present embodiment is characterized in that a diode bridge (circuit) 112 is used. The diode bridge 112 is normally used as a commutator, but functions as switching means by being connected as in this embodiment. As a result, it is possible to provide a switching means which can be reduced in size and which has high reliability in terms of movement resistance and life.

The operation of this embodiment will be described below.

First, when the electric vehicle is running, the external AC power supply 10 is disconnected. The diode 6a of the lower arm of the phase C of the power converter 6 and the two pairs of diodes connected in series in the diode bridge 112 are connected in parallel. Does not flow. Therefore, it is electrically disconnected.

When charging the electric vehicle, the external AC power supply 10 is connected to the diode bridge 112 as shown in FIG.
To the synchronous motor 2 and the power converter 6 via the. The diode bridge 112 performs full-wave rectification on the AC voltage input from the external AC power supply 10 and applies the AC voltage to the synchronous motor 2 and the power converter 6. Thus, a chopper is formed by the inductance of the synchronous motor 2 and the power converter 6, and the power converter 6 acts as a PWM converter. At this time, the controller 8 always turns off two sets of switching elements (transistors) included in the C phase of the power converter 6.
To The switching of the A phase and the B phase is turned ON / OFF as in the first embodiment. Therefore, when the output voltage Vdc is boosted for charging, the output voltage and the external AC power 10
Since the relation of the voltage e is Vdc> | e |, no current flows in the C phase. Therefore, the C phase is separated.

As described above, according to the present embodiment, by using the diode bridge 112 as the switching means, it is possible to improve the reliability and further reduce the size and weight. Of course, as in the first embodiment, it is needless to say that not only the rotation of the synchronous motor 2 can be prevented during charging, but also the control of the power factor 1 that does not cause harmonic interference can be realized.

[0039]

According to the present invention, the controller controls the current flowing through the field coils wound around the respective stators, and controls the electric field in the direction of the electrical angle formed by the permanent magnets or salient poles of the rotor during charging. Since the control can be performed so as to match the direction of the magnetic field formed by the magnetic coil, the synchronous motor can be locked without rotating during charging. As a result, the movement of the electric vehicle at the time of charging can be reliably prevented, so that the vehicle is safe.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of an electric vehicle according to the present invention.

FIG. 2 is a connection diagram of main parts of the electric vehicle shown in FIG.

FIG. 3 is an equivalent circuit diagram of a main part of the electric vehicle shown in FIG.

FIG. 4 is a diagram for explaining the relationship between the direction of the magnetic field of the field coil and the direction of the magnetic field of the rotor in the embodiment.

FIG. 5 is a control block diagram showing a converter PWM algorithm in the present embodiment.

FIG. 6 is a control block diagram showing details of a control law of a converter PWM algorithm in the present embodiment.

FIG. 7 is an overall configuration diagram showing a second embodiment of the electric vehicle according to the present invention.

FIG. 8 is a connection diagram of main parts of the electric vehicle shown in FIG.

9 is an equivalent circuit diagram of a main part of the electric vehicle shown in FIG.

[Explanation of symbols]

1 electric vehicle, 2 synchronous motor, 2a permanent magnet, 2
b Field coil, 4 traveling storage battery, 6 Power converter, 8
Controller, 9 electrolytic capacitor, 10 external AC power supply, 12 switch section, 14a, 14b AC current sensor, 16 DC voltage sensor, 18 DC current sensor, 20
Electrical angle detection sensor, 112 diode bridge.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-214592 (JP, A) JP-A-7-87616 (JP, A) JP-A-6-6910 (JP, A) JP-A-5- 236609 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60L 11/18 B60L 9/18 H02P 7/63 303

Claims (1)

(57) [Claims] 1. A synchronous motor having a stator on which a field coil is wound, a rotor having a permanent magnet or a salient pole provided on a surface facing the stator, and switching of the number of phases of the field coil of the synchronous motor. Power conversion means having an element pair and a flywheel diode connected in parallel with the switching element in reverse current direction, wherein an output terminal as a connection portion of each switching element pair is connected to an input terminal of the synchronous motor; A traveling storage battery in which both positive and negative electrodes are connected to input terminals at both ends of each switching element pair of the power conversion means; and DC power input to the input terminal of the means is converted to AC and output from the output terminal, or AC input to the output terminal of the power conversion means A controller that converts electric power into direct current and outputs the electric power from an input terminal. An electric vehicle, comprising: an external AC power source for charging the traveling storage battery, the electric power converting means and one phase of a field coil of the synchronous motor. Switching means for inserting and connecting to a system, and electrical angle detecting means for detecting an electrical angle of the rotor, wherein the controller controls the energization timing of the switching element when charging the storage battery for traveling. AC power from the external AC power source is controlled to match the direction of the magnetic field formed by the field coils of each phase with the direction of the electrical angle of the rotor detected by the electrical angle detecting means. Electric car.