JPH09168205A - Electrical system of hybrid electric car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact, light, inexpensive, and efficient hybrid electric car with less communication trouble. SOLUTION: An electric car has a plurality of semiconductor power converters with either a main battery or an engine drive AC generator as a power supply. A resonance circuit 140 for generating a high-frequency AC voltage is connected to a main battery 1. The frequency of the output voltage of an AC generator 30 is made equal to the output voltage of the resonance circuit 140 and either the resonance circuit 140 or the AC generator 30 can be connected to a plurality of power converters 60, 801, 100, and 120 via a selection switch 50. The power converters 60, 801, 100, and 120 convert an input voltage to a pulse train of high-frequency AC voltage half-wave waveform by operating an internal semiconductor switch, thus obtaining a desired output voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric system of a hybrid electric vehicle driven by a battery and an engine-driven AC generator as a power source.

[0002]

2. Description of the Related Art FIG. 3 shows a typical prior art of this type of electrical system. In the figure, 1 is a main battery, 2
Is an engine, 3 is an AC generator, 4 is a rectifier, 5 is a changeover switch, 6 is a semiconductor power converter, and 7 is an electric motor for driving a vehicle. Here, when the electric motor 7 is an AC electric motor,
The power converter 6 is usually composed of an inverter. Further, the electric motor 7 drives the wheels via a speed reducer or a differential device (not shown).

Reference numeral 8 is a charger for charging the auxiliary battery 9,
Generally, a DC-DC converter is used. Charger 8
Corresponds to the alternator of the engine vehicle. Further, 10 is an inverter for driving the air conditioner electric motor 11, and 12 is an inverter for driving the power steering electric motor 13.

In the hybrid electric vehicle of the system shown in FIG. 3, in the case of battery driving, the changeover switch 5 is connected to the main battery 1 side and the vehicle is driven by using the main battery 1 as a power source. In the case of engine driving, the changeover switch 5 is connected to the rectifier 4 side to operate the engine 2, and the rectifier 4 converts the AC voltage of the generator 3 into a DC voltage equivalent to that of the main battery 1 to drive the vehicle. .

The above hybrid electric vehicle employs a system in which the equipment is operated from a DC power source through various power converters, which will be described below. FIG.
As the power converter 6, a three-phase voltage source inverter, which is a typical circuit configuration of an inverter, is illustrated.
62 is a transistor, 63 and 64 are diodes, and 65 is a DC input smoothing capacitor. The other inverters 10 and 12 in FIG. 3 have substantially the same configuration.

FIG. 5 shows an example of the charger 8 in FIG. 3, which is generally called a DC-DC converter. In FIG. 5, 81 is a single-phase inverter, 82 is a DC input smoothing capacitor, 83 is an insulating transformer for electrically insulating the DC circuit on the input side from the auxiliary battery 9, and 84.
Is a rectifier, and 85 is a DC output smoothing filter.

In this system, the operating frequency of the inverter 81 is several hundred KHz in order to miniaturize the insulation transformer 83.
It is set above. The above-mentioned inverters 10 and 12 also generally perform PWM control operation, and the inverter frequency is several KHz or less and the carrier frequency is several tens KHz or less.

FIG. 6 shows an example of the waveform of the voltage between the output lines of the PWM-controlled voltage source inverter, in which the number of output voltage pulses is 9.
It is shown in the case of. In this case, the output line voltage waveform is a rectangular wave voltage pulse train having a peak value of the DC voltage Edc (voltage of the main battery 1). In the figure, the broken line shows the voltage waveform of the fundamental wave component of the inverter output frequency. The power converter 6 and the inverter 1 in FIG.
0 and 12 are usually voltage type PWM control inverters,
The output waveform is as shown in FIG.

FIG. 7 shows an output voltage waveform of the insulation transformer 83 shown in FIG. The inverter 81 has a switching cycle T (switching frequency f = 1 / T of the inverter 81) and conduction time Ton (conduction rate α = Ton / T).
Running on. Note that n is the winding ratio of the insulation transformer 83. As shown in FIG. 7, the input of the rectifier 84 is Edc /
The rectangular wave voltage has a peak value of n. Further, as the control of the charger 8, the conduction ratio α is controlled.

[0010]

As described above, in the electric system of the conventional hybrid electric vehicle, the AC voltage waveform of the semiconductor power converter that converts the DC voltage into the AC voltage is a rectangular wave pulse train. In this way, when the voltage pulse waveform of the output of the power converter is a rectangular wave, a leakage current flows through the insulator between the vehicle-mounted device and the vehicle body frame, and this current causes communication failure to electronic devices such as car radios. It causes big problems.

In the case of an electric vehicle, it is necessary to reduce this leakage current to a level below which communication failure does not pose a practical problem. As a countermeasure against this, the following means have been conventionally taken. (1) A conventional voltage source inverter is used as the power converter, and the power converter (inverter) is used as shown in FIG.
The zero-phase reactor 501 is inserted into the AC side of 6, and the zero-phase reactor 502 is inserted into the DC side. This method is the same for other inverters.

(2) The snubber circuit of the switching circuit of the voltage source inverter is strengthened so that the voltage of the rectangular wave voltage waveform rises gently. (3) Each power converter is a resonant inverter, and the voltage pulse waveform of the output is changed from a rectangular wave to a sine wave.

FIG. 9 shows a basic circuit of a resonance type inverter, in which 14 is an LC resonance circuit and 15 is a switch circuit. Here, the figure shows only one arm, and a three-phase inverter has a three-arm configuration.

FIG. 10 shows the operation of FIG.
(A) is a resonance voltage waveform of the resonance circuit 14, that is, an input voltage waveform of the switch circuit 15. In this case, the peak value is twice the DC voltage Edc. Further, (b) is an output voltage waveform (between lines) of the switch circuit 15, which is shown in correspondence with FIG. 6. The broken line in FIG. 10B corresponds to the broken line in FIG.

The switch circuit 15 operates as if it were a rectifier having a resonance voltage as an input. When the output voltage of the inverter is low, the number of pulses is reduced, and when the output voltage is high, the switch circuit 15 is operated so that the number of pulses is increased. , PDM for the above PWM
(Pulse Density Modulation)).

As described above, in the conventional electric system of the hybrid electric vehicle, it is possible to individually reduce the noise by, for example, using a resonant inverter for each of the plurality of power converters. (1) The power converter becomes expensive. (2) The power converter becomes large and heavy. However, it has not been put to practical use. Therefore, the present invention has been made to solve these problems.

[0017]

The present invention has been made paying attention to the fact that the output voltage of all power converters connected to the DC circuit of a conventional hybrid electric vehicle is a combination of voltage pulse trains. A common high-frequency resonance circuit is connected to a DC circuit having a battery, and the high-frequency resonance voltage of the resonance circuit is input to each power converter when driven by the battery. Further, paying attention to the fact that the output voltage of the engine-driven AC generator is also an AC voltage, and when driving by the engine, the output voltage of the generator is input to each power converter at the same frequency as the high frequency resonance voltage. And each power converter,
The input voltage is converted into a pulse train of a high frequency AC voltage half-wave waveform and output, and power is supplied to various electric motors such as a vehicle driving AC electric motor and auxiliary batteries.

That is, the invention according to claim 1 is an electric system of a hybrid electric vehicle equipped with a plurality of semiconductor power converters which use either one of a main battery and an engine-driven AC generator as a power source. Is connected to the main battery, the frequency of the output voltage of the AC generator is the same as the output voltage of the resonance circuit, and one of the resonance circuit and the AC generator is switched. The power converter is configured to be connectable to the power converter via a switch, and the power converter operates an internal semiconductor switch to convert an input voltage into a pulse train of a high frequency AC voltage half-wave waveform to output a desired output voltage. It is characterized in that it is obtained.

According to a second aspect of the present invention, in the electric system according to the first aspect, the power converter is at least for driving a vehicle, driving an air conditioner, driving power steering,
It is characterized by including a power converter for charging the auxiliary battery.

The invention according to claim 3 is the invention according to claim 1 or 2
In the electric system described above, the alternating-current generator is a single-phase alternating-current generator.

[0021]

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 block diagram showing the configuration of the embodiment, and the same components as those in FIG. 3 are given the same numbers.

In FIG. 1, reference numeral 20 is a high-speed engine such as a gas turbine engine, and a high-frequency single-phase AC generator 3
Drive 0. Reference numeral 140 is a high-frequency resonance circuit connected to the main battery 1, and corresponds to the resonance circuit 14 in FIG. Here, the frequency of the AC output voltage of the AC generator 30 is set to be substantially the same as the resonance frequency of the resonance circuit 140. FIG. 2 shows FIG.
(A) shows the output voltage waveform of the resonance circuit 140 and the AC generator 30. Edc is the voltage of the main battery 1.

Further, in FIG. 1, 50 is an AC generator 3.
It is a changeover switch for switching between the output of 0 and the output of the resonance circuit 140. Further, reference numeral 60 denotes a semiconductor power converter for driving the vehicle driving AC electric motor 70 which operates with the voltage of the high frequency pulse train, and constitutes a resonance type inverter corresponding to the switch circuit 15 of FIG. The power converter 60 converts the high frequency AC voltage into an AC voltage which is a pulse train of a half wave waveform of a high frequency voltage waveform having a required number of pulses. 2B shows the output voltage waveform of the power converter 60, which corresponds to FIG. 10B.

Reference numeral 80 in FIG. 1 denotes a charger for the auxiliary battery 9,
It is composed of a power converter 801, an insulation transformer 802, and a rectifying / smoothing circuit 803. The power converter 801 corresponds to the single-phase inverter 81 in FIG. 5 and converts the high frequency AC voltage into an AC voltage which is a pulse train of a half wave waveform of the high frequency voltage waveform of the required number of pulses. FIG. 2C shows an output voltage waveform of this power converter 801, where T indicates a switching cycle. The insulating transformer 802 insulates the input / output side and reduces the voltage to a voltage suitable for charging the auxiliary battery 9, and the rectifying / smoothing circuit 803 corresponds to the rectifier 84 and the smoothing filter 85 in FIG.

Further, reference numerals 100 and 120 in FIG. 1 are power converters having the same structure and operation as the power converter 60. Furthermore, 1
Reference numerals 10 and 130 denote an air conditioner electric motor and a power steering electric motor that operate with an AC voltage that is a pulse train of a half-wave waveform of a high-frequency voltage waveform, and correspond to the electric motors 11 and 13 of FIG. 3, respectively.

Now, in this embodiment, when driven by a battery, the changeover switch 50 is connected to the main battery 1 side and the resonance circuit 140 is operated to generate the resonance voltage shown in FIG. 2 (a). Then, this resonance voltage is applied to each power converter 6
0, 801, 100, 120 to input AC motor 70
Also, the electric motors 110 and 130 are driven to charge the auxiliary battery 9. Since the starting circuit and the control circuit of the resonance circuit 140 are the same as those of the related art, their illustration and description are omitted.

Further, at the time of driving by the engine, the changeover switch 50 is connected to the AC generator 30 side so that the engine 20
Is driven to cause the AC generator 30 to output a single-phase AC voltage equal to the resonance frequency of the resonance circuit 140. Then, this AC voltage is applied to each of the power converters 60, 801, 100, 120.
To drive the AC electric motor 70 and the electric motors 110, 130 to charge the auxiliary battery 9. Where the engine 20
Since the details of the power generation control by the AC generator 30 are not the main part of the present invention, the description thereof will be omitted.

In the above embodiment, the case where the single-phase AC generator 30 is used as the engine generator has been described, but it is also possible to use an AC generator other than the single-phase generator.

[0029]

As described above, in the present invention, the input voltage of each power converter is a common high-frequency AC voltage in both cases of engine driving and battery driving, and this voltage is desired by each power converter. Since the pulse train is converted and output, the following effects can be expected.

(1) Since the output voltage waveforms of all the power converters can be made substantially sinusoidal, the leakage current flowing through the body frame can be reduced, and the radio interference and other communication obstacles can be greatly reduced. can do. (2) Since the resonance circuit is shared by all the power converters when the battery is driven, it is possible to reduce the size and weight of the on-vehicle device and reduce the cost of the entire electric vehicle.

(3) Since each power converter is of the resonance circuit type, the switching loss of the power converter is reduced and the efficiency of the electric vehicle as a whole can be improved. (4) When the engine is driven, a high-frequency AC voltage having the same frequency as the resonance voltage of the resonance circuit is generated by the generator and directly input to each power converter, so the AC voltage is first converted to a DC voltage. Compared with the conventional method of generating a high frequency AC voltage via a resonance circuit, the efficiency is greatly improved and the fuel consumption is also improved.

As described above, according to the present invention, it is possible to provide a small-sized, lightweight, low-priced, high-efficiency hybrid electric vehicle with few communication failures.

[Brief description of the drawings]

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

FIG. 2 is an operation explanatory diagram of FIG. 1;

FIG. 3 is a block diagram showing a configuration of a conventional technique.

FIG. 4 is a configuration diagram of an inverter in FIG.

5 is a configuration diagram of the charger in FIG.

FIG. 6 is an output voltage waveform diagram of the inverter of FIG.

7 is an output voltage waveform diagram of the transformer in FIG.

FIG. 8 is a diagram showing a known method for reducing the leakage current of an electric vehicle.

FIG. 9 is a configuration diagram of a basic circuit of a resonant inverter.

FIG. 10 is a diagram illustrating the operation of the inverter shown in FIG.

[Explanation of symbols]

 1 Main Battery 9 Auxiliary Battery 20 Engine 30 AC Generator 50 Changeover Switch 60, 100, 120, 801 Semiconductor Power Converter 70 AC Motor 80 Charger 802 Insulation Transformer 803 Rectification Smoothing Circuit 110 Air Conditioner Motor 130 Power Steering Motor 140 Resonant circuit

Claims (3)

[Claims] 1. In an electric system of a hybrid electric vehicle equipped with a plurality of semiconductor power converters using either one of a main battery and an engine-driven AC generator as a power source, a resonance circuit for generating a high frequency AC voltage is provided in the main circuit. The power converter is connected to a battery, and the frequency of the output voltage of the AC generator is the same as the output voltage of the resonance circuit, and one of the resonance circuit and the AC generator is connected via a changeover switch to the power converter. The power converter is configured to operate the internal semiconductor switch to convert the input voltage into a pulse train of a high frequency AC voltage half-wave waveform to obtain a desired output voltage. Electric system for hybrid electric vehicles. 2. The electric system for a hybrid electric vehicle according to claim 1, wherein the power converter includes at least a power converter for driving a vehicle, driving an air conditioner, driving power steering, and charging an auxiliary battery. The electric system of the hybrid electric vehicle that features. 3. The electric system for a hybrid electric vehicle according to claim 1, wherein the AC generator is a single-phase AC generator.