JP3173151B2 - Electric vehicle electric system - 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 system for an electric vehicle that uses a battery as a power source and drives an AC motor for driving wheels via an inverter.

[0002]

2. Description of the Related Art FIG. 8 shows a known drive system of an electric vehicle which uses a battery as a power source and drives wheels by an AC motor via an inverter. In the figure, reference numeral 1 denotes a battery, which is formed by connecting a required number of unit batteries 100 in series. Reference numeral 4 denotes an inverter, which is an AC motor for driving wheels.
Drive. Reference numeral 3 denotes a protection fuse, which is used as needed. Reference numeral 2 denotes a main switch for electrically connecting or disconnecting the battery 1 and the inverter 4. The shaft of the electric motor 5 is connected to the differential 7 through the speed reducer 6 and drives the wheels 81 and 82.

An electric vehicle is a vehicle that uses a battery as a power source as described above. However, since it is used equally with an engine vehicle, the following is required. 1) Good vehicle performance, that is, good acceleration performance. One charge traveling distance is long. 2) High reliability and good maintainability. To meet such demands, 3) Driving electric vehicles The system must be highly reliable. 4) The equipment must be small, lightweight, and highly efficient. 5) The price must be low.

[0004]

FIG. 8 shows a conventional general electric system. In this electric system, one wheel drive AC motor 5 is driven by one inverter 4. At present, it cannot be said that the system has sufficiently high operation reliability as an electric vehicle drive system. That is, the current vehicle drive system of the engine vehicle has a sufficient reliability including the maintenance system, but the operation reliability of the drive system of the electric vehicle cannot be said to be sufficient as compared with that of the engine vehicle.

That is, in the system shown in FIG.
Or, if the AC motor 5 fails, it is no longer possible to operate as an electric vehicle. In order to spread electric vehicles as well as engine vehicles, it is essential that the operation reliability of this drive system be sufficiently high and that the system be of no concern to the user. As a solution to the above, there is a method of duplicating the system in FIG. 8, but there is a problem in cost. Further, even in a system in which each of the left and right wheels 81 and 82 is driven separately, if one of the drive systems goes down, the vehicle runs one wheel, which is a problem in running performance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to significantly increase the reliability of an electric vehicle drive system at a price similar to that of a known electric system, and to improve an engine vehicle. It is an object of the present invention to provide an electric system of an electric vehicle capable of obtaining a traveling performance comparable to that of an electric vehicle.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a four-phase two-phase two-phase winding for a motor for driving a wheel, and a half bridge for each winding of each group. By connecting a single-phase inverter, the drive system consisting of two-phase inverters is duplicated. When the inverters and the electric motors are normal, by operating the two two-phase inverters, the whole is operated as a four-phase inverter, and the electric motor is driven as a four-phase electric motor. If one of the two-phase drive systems fails, the power supply circuit of the failed system is opened, and the motor is driven as a two-phase motor by the remaining sound two-phase drive system.

[0008]

According to the present invention, when all inverters and motors are sound, two two-phase inverters consisting of two half-bridge type single-phase inverters are operated to form a four-phase inverter, and the motor is driven by the four-phase operation. I do. If one of the two-phase inverters fails, the failed system is disconnected, and the other two-phase inverter operates the motor in two phases. In this case, the motor output is halved compared to the normal four-phase operation, the number of phases is also reduced from four to two, and the torque pulsation is increased.However, the running of the electric vehicle does not impair the running performance of the electric vehicle practically. It is possible to do.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing one embodiment of the present invention. A battery 1 formed by connecting a plurality of unit batteries 100 in series has a series battery group 11 in which the number of unit batteries 100 is halved.
0, 120, and the intermediate potential connection line 13
0 is provided. 2Pa, 2Pb, 2Na, 2Nb
Is a main switch, and one end of each of them is connected to the positive electrode side 140 and the negative electrode side 150 of the battery 1 as shown in the figure. Further, fuses 3P and 3N are connected to the other ends of the main switches 2Pa and 2Nb, respectively.

Reference numerals 40a and 40b denote two-phase inverters each composed of two half-bridge type single-phase inverters, and the AC output side thereof has feed lines 51a ₁ , 51a ₂ , 51b ₁ , and 5b.
1b ₂ is connected to a four-phase AC motor 50 for driving wheels. 51 m is a neutral wire of the winding of the AC motor 50. The two-phase inverters 40a and 40b are connected to the battery 1 via main switches 2Pa, 2Pb, 2Na, and 2Nb.
Feed line 14 connected to the positive side 140 and the negative side 150 of the
1a, 141b, 151a, and 151b. 140a and 140b are intermediate potential connection lines. Note that, in FIG. 1, the configuration of the driving devices after the electric motor 50 is the same as that in FIG.

FIG. 2 is a diagram showing details of the two-phase inverter 40a. 41a _1, 41a ₂ is a half-bridge single-phase inverter, single-phase inverters 41a ₁ is the feed line 5
1a ₁ and the single-phase inverter 41a ₂ is connected to a feeder line 51a.
₂ is configured to supply power to each. The configuration of these inverters 41a ₁ and 41a ₂ is the same as that of one phase of a conventional three-phase inverter, and therefore detailed description is omitted.

42 Pa and 42 Na are two-phase inverters 4
0a is a power supply capacitor that divides the input voltage of Oa by half. An intermediate potential connection line 140a from the connection point is connected to the intermediate potential connection line 130 of the battery 1 and a four-phase winding of the motor 50. Neutral wire 51m (see FIGS. 1 and 3),
50m and connected to. The configuration of the other two-phase inverter 40b is also the same as that of the two-phase inverter 40a, and the symbol “a” of each component may be replaced with “b”.

FIG. 3 is a diagram showing details of the stator windings of the electric motor 50. 50 a ₁ , 50 a ₂ , 50 b ₁ , 50 b ₂ are windings of each phase, and the winding 50 a ₁ is a two-phase inverter 40.
a is fed via a feeder line 51a ₁ from single-phase inverters 41a ₁ of the winding 50a ₂ is fed via the feed line 51a ₂ from single-phase inverters 41a _2. Winding 50b _1, winding 5
0b ₂ likewise fed via respective power supply lines 51b _1, 51b ₂ from single-phase inverter 41b _1, 41b ₂ of the two-phase inverter 40b.

Next, the operation of this embodiment will be described. First, a half-bridge single-phase inverter will be described. FIG. 4 shows the half-bridge type single-phase inverter 4 of FIG.
1a ₁ and the connection diagram of windings 50a ₁ of FIG. 3, FIG. 5 is a diagram depicting the operation thereof. Here, the voltage polarity of the winding 50a ₁ to the direction of the arrow in FIG positive.

Firstly, ON Then winding voltage TR1 (in which shown in transistors TR1, TR2 in the drawing) semiconductor switch of the single-phase inverters 41a ₁ is positive, the voltage value V as shown in FIG. 5 _B / 2 (V _B is the battery voltage) becomes. When the semiconductor switch TR1 is turned off and the semiconductor switch TR2 is turned on, the winding voltage becomes negative and −V _B / 2
Becomes By ON / OFF alternately semiconductor switches TR1, TR2 thus, an AC voltage applied to the windings 50a _1. By also be performed for such a switching operation single-phase inverter 41a ₂ other and can be operated inverters 40a as a two-phase inverter. Further, the remaining single-phase inverters 41b ₁ , 41b
by the same switching operation also b _2, the inverter 40b can be operated as a two-phase inverter.

FIG. 6 is an explanatory diagram of the operation when the two-phase inverters 40a and 40b and the electric motor 50 are sound.
Shows the time course of the winding _{50a 1, 50a 2, 50b 1} , the voltage waveform applied to 50b _2. Two-phase inverter 40
a, 40b, in other words, if all the half-bridge type single-phase inverters 41a ₁ , 41a ₂ , 41b ₁ , 41b ₂ are sound, the two two-phase inverters 40a, 40b operate as a four-phase inverter, and 50 windings 5
By supplying _{0a 1, 50a 2, 50b 1} , sequentially voltages 50b _2, the electric motor 50 to drive four-phase.

FIG. 7 is an explanatory diagram of the operation at the time of the inverter failure, and shows the lapse of time of the voltage waveform applied to the windings 50a ₁ and 50a ₂ . In this example, one two-phase inverter 40
b when a failure occurs. In this case, the failure is detected by appropriate means and the main switch 2P shown in FIG.
The power supply circuit of the inverter 40b is opened by b and 2Nb, and only the inverter 40a is operated. That is, the half-bridge type single-phase inverters 41a ₁ and 41a ₂ are driven to operate only the sound inverter 40a as a two-phase inverter, and only the windings 50a ₁ and 50a ₂ are supplied with a voltage as shown in FIG. Is operated in two phases. Inverter 4
If 0a fails, the power supply circuit of the inverter 40a is opened by the main switches 2Pa and 2Na, and the healthy inverter 40b is similarly operated as a two-phase inverter.

When two-phase operation is performed by only one of the two-phase inverters, the motor output is halved compared to the normal four-phase operation, the number of phases is reduced from four to two, and torque pulsation increases. In addition, it is possible to sufficiently drive the electric vehicle so that the driving performance of the electric vehicle is not impaired practically. Further, in the above embodiment, the case where the inverter has failed has been described. However, the present invention can cope with a failure inside the motor such as a short-circuit or disconnection of the motor winding corresponding to the two-phase inverter.

Although the output voltage waveform of each single-phase inverter is shown by a non-PWM waveform for convenience in the above description of the operation of FIGS. 5 to 7, the output voltage waveform of the inverter is usually PWM.
It becomes a waveform controlled by M. Since the contents of the PWM control are well known, the description is omitted here.

[0020]

As described above, according to the present invention, when all of the inverters and the electric motors are sound, two two-phase inverters composed of two half-bridge type single-phase inverters are operated to form a four-phase inverter. The motor is driven by the four-phase operation, and if one of the two-phase inverters fails, the faulty system is disconnected to operate the motor by the other two-phase inverter, thereby providing the following effects.

1) Even if one two-phase inverter fails,
Since the electric vehicle can be driven by the two-phase operation by the remaining two-phase inverters, the operation reliability of the electric system is greatly improved, and the effect is extremely large in practical use. 2) In this case, the electric motor output is reduced by half, but only the acceleration / deceleration performance and the highest speed driving performance of the vehicle are reduced, and the normal running performance is not reduced. The effect in making this is great. 3) The two inverters that constitute the two-phase inverter are half-bridge type, and the whole system is one in which one phase is added to the conventional three-phase inverter, so that the cost performance is improved and the system is compact. The weight can be reduced. As a result, it is possible to realize an electric system that is comparable in performance to conventional electric systems and drive systems for engine vehicles.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a two-phase inverter in the embodiment of FIG.

FIG. 3 is an explanatory diagram of a stator winding of the electric motor in the embodiment of FIG.

FIG. 4 is a connection diagram of a half-bridge type single-phase inverter and a stator winding.

FIG. 5 is an operation explanatory diagram of FIG. 4;

FIG. 6 is a diagram showing a lapse of time of a winding voltage indicating a normal operation.

FIG. 7 is a diagram showing a lapse of time of a winding voltage showing an operation at the time of failure of one two-phase inverter.

FIG. 8 is a configuration diagram of a known drive system in the related art.

[Explanation of symbols]

1 Battery 100 Unit Battery 110, 120 Series Battery Group 130, 140a, 140b Intermediate Potential Connection Line 141a, 141b, 151a, 151b Feed Line 2Pa, 2Pb, 2Na, 2Nb Main Switch 3P, 3N Fuse 40a, 40b Two-Phase Inverter 41a ₁ , 41a ₂ Half-bridge type single-phase inverter 42 Pa, 42 Na Power supply capacitor 50 AC motor 50 a ₁ , 50 a ₂ , 50 b ₁ , 50 b ₂ Windings 51 a ₁ , 51 a ₂ , 51 b ₁ , 51 b ₂ Power supply line 50 m, 51 m Neutral line

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Motoyoshi Yoshi, 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Yoshio Ito 1st Tanabe Nitta, Kawasaki-ku, Kawasaki-ku, Kanagawa No. 1 Fuji Electric Co., Ltd. (56) References JP-A-59-213295 (JP, A) JP-A-51-32913 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60L 1/00-15/42

Claims (3)

(57) [Claims] 1. An electric system for an electric vehicle in which a battery is used as a power source and an AC motor for driving wheels is driven via an inverter, wherein the inverter comprises two two-phase half-bridge type single-phase inverters. The AC motor is constituted by an electric motor having a four-phase winding, and the AC output-side power supply line of each half-bridge type single-phase inverter is connected to the four-phase winding of the AC motor.
An electric system for an electric vehicle, wherein the two-phase inverter enables four-phase operation of the AC motor. 2. The electric system for an electric vehicle according to claim 1, further comprising means for opening a power supply circuit of the failed inverter when one or both of the two two-phase inverters fail. 3. The electric vehicle according to claim 2, wherein when one of the two two-phase inverters fails, the power supply circuit of the failed inverter is opened, and the AC motor is operated in two phases only by the other healthy inverter. Electrical system.