JP3334742B2 - Electric system of hybrid electric vehicle - 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 a hybrid electric vehicle driven by a battery and an engine-driven alternator.

[0002]

2. Description of the Related Art FIG. 3 shows a typical prior art of such an electric 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 a motor for driving the vehicle. Here, when the motor 7 is an AC motor,
Power converter 6 is usually constituted by an inverter. The electric motor 7 drives the wheels via a speed reducer or a differential device (not shown).

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

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

[0005] The hybrid electric vehicle employs a system in which equipment is operated from a DC power supply via various power converters, and these will be described below. FIG.
As a 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 shown in FIG. 3, which is generally called a DC-DC converter. 5, reference numeral 81 denotes a single-phase inverter; 82, a DC input smoothing capacitor; 83, an insulating transformer for electrically insulating the input side DC circuit from the auxiliary battery 9;
Is a rectifier, and 85 is a DC output smoothing filter.

In the case of this system, the operating frequency of the inverter 81 is several hundred KHz in order to reduce the size of the insulating transformer 83.
It is set above. In general, the inverters 10 and 12 also perform the 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 a voltage waveform between output lines of a voltage-controlled inverter under PWM control.
It is shown in the case of. In this case, the output line voltage waveform is a rectangular wave-shaped voltage pulse train whose peak value is the DC voltage Edc (voltage of the main battery 1). In the figure, the broken line indicates the voltage waveform of the fundamental component of the inverter output frequency. Power converter 6 and inverter 1 in FIG.
0 and 12 are voltage-type PWM control inverters,
The output waveform is as shown in FIG.

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

[0010]

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

In the case of an electric vehicle, it is necessary to reduce the leakage current to a level at which communication failure does not cause a practical problem, and the following measures have conventionally been taken as a countermeasure. (1) As a power converter, a conventional voltage source inverter is used, and as shown in FIG. 8, a power converter (inverter)
6, a zero-phase reactor 501 is inserted on the AC side, and a zero-phase reactor 502 is inserted on 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 to make the rising of the voltage of the rectangular wave voltage waveform gentle. (3) The power converters are individually resonant inverters, and the output voltage pulse waveform is changed from a rectangular wave to a sine wave.

FIG. 9 shows a basic circuit of a resonance type inverter, wherein 14 is an LC resonance circuit, and 15 is a switch circuit. Here, this figure shows only one arm, and in the case of a three-phase inverter, it 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. 6B shows an output voltage waveform (between lines) of the switch circuit 15, which is shown in correspondence with FIG. 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 small, the number of pulses is reduced, and when the output voltage is large, the switch circuit 15 is operated so as to increase the number of pulses. , PDM for the aforementioned PWM
(Pulse Density Modulation).

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

[0017]

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

That is, according to the first aspect of the present invention, there is provided an electric system of a hybrid electric vehicle including a plurality of semiconductor power converters powered by one of a main battery and an engine-driven AC generator. Is connected to the main battery, and the frequency of the output voltage of the AC generator and the resonance frequency of the resonance circuit
Almost the same, one of the resonance circuit and the AC generator is configured to be connectable to the power converter via a changeover switch, and the power converter is operated by operating an internal semiconductor switch to input. It is characterized in that a voltage is converted into a pulse train having a high-frequency AC voltage half-wave waveform to obtain a desired output voltage.

According to a second aspect of the present invention, in the electric system according to the first aspect, the power converter includes at least a vehicle drive, an air conditioner drive, a power steering drive,
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
The electrical system according to claim 1, wherein the alternator is a single-phase alternator.

[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 denoted by the same reference numerals.

In FIG. 1, reference numeral 20 denotes a high-speed engine such as a gas turbine engine.
Drive 0. Reference numeral 140 denotes 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 substantially equal to the resonance frequency of the resonance circuit 140. FIG. 2 shows FIG.
(A) shows an output voltage waveform of the resonance circuit 140 and the AC generator 30. Edc is the voltage of the main battery 1.

In FIG. 1, reference numeral 50 denotes the alternator 3
This is a changeover switch that switches between an output of 0 and an output of the resonance circuit 140. Further, reference numeral 60 denotes a semiconductor power converter for driving the AC motor 70 for driving the vehicle, which operates at the voltage of the high-frequency pulse train, and corresponds to the switch circuit 15 in FIG. 9 and constitutes a resonant inverter. The power converter 60 converts the high-frequency AC voltage into an AC voltage that is a pulse train of a half-wave waveform of a high-frequency voltage waveform having a required number of pulses. FIG. 2B shows an output voltage waveform of the power converter 60, and corresponds to FIG.

In FIG. 1, reference numeral 80 denotes a charger for the auxiliary battery 9;
It comprises a power converter 801, an insulating transformer 802, and a rectifying / smoothing circuit 803. The power converter 801 corresponds to the single-phase inverter 81 in FIG. 5, and converts a high-frequency AC voltage into an AC voltage that is a half-wave pulse train of a high-frequency voltage waveform having a required number of pulses. FIG. 2C shows an output voltage waveform of the 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.

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

In this embodiment, the switch 50 is connected to the main battery 1 when the battery is driven, and the resonance circuit 140 is operated to generate the resonance voltage shown in FIG. Then, this resonance voltage is applied to each power converter 6.
0, 801, 100, 120 and input to the AC motor 70
Then, the 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 in the related art, illustration and description are omitted.

When the engine is driven, the switch 50 is connected to the alternator 30 and the engine 20 is turned on.
To output a single-phase AC voltage equal to the resonance frequency of the resonance circuit 140 from the AC generator 30. Then, this AC voltage is applied to each of the power converters 60, 801, 100, 120.
To drive the AC motor 70 and the motors 110 and 130 to charge the auxiliary battery 9. Here, 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 is omitted.

In the above embodiment, the case where the single-phase AC generator 30 is used as the engine generator has been described. However, an AC generator other than a single-phase AC generator can be used.

[0029]

As described above, in the present invention, the input voltage of each power converter is set to a common high-frequency AC voltage regardless of whether the engine is driven or the battery is driven, and this voltage is applied to the desired power by each power converter. Since the output is converted into a pulse train, the following effects can be expected.

(1) Since the output voltage waveforms of all the power converters can be made substantially sinusoidal, leakage current flowing through the vehicle body frame is reduced, and communication failures such as radio interference are greatly reduced. can do. (2) Since the resonance circuit is shared by all the power converters when the battery is driven, the size and weight of the on-board equipment and the price of the electric vehicle as a whole can be reduced.

(3) Since each power converter is of a 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) In the case of driving the engine, 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 that the AC voltage is temporarily converted to a DC voltage. Compared with the conventional method of generating a high-frequency AC voltage through 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, lightweight, low-cost, high-efficiency hybrid electric vehicle with less communication disturbance.

[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. 3;

FIG. 5 is a configuration diagram of a charger in FIG. 3;

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

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

FIG. 8 illustrates a known method for reducing the leakage current of an electric vehicle.

FIG. 9 is a configuration diagram of a basic circuit of a resonance type inverter.

FIG. 10 is an operation explanatory diagram of the inverter of FIG. 9;

[Explanation of symbols]

 DESCRIPTION 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 Rectifying smoothing circuit 110 Air conditioner motor 130 Power steering motor 140 Resonance circuit

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI H02M 7/48 B60K 9/00 E (58) Field surveyed (Int.Cl. ⁷ , DB name) B60K 6/02 B60K 6 / 04 B60L 11/08 B60L 3/00 B60L 11/18 H02M 7/48

Claims (3)

(57) [Claims] An electric system for a hybrid electric vehicle including a plurality of semiconductor power converters powered by one of a main battery and an engine-driven AC generator, wherein a resonance circuit for generating a high-frequency AC voltage is provided by the main circuit. Connected to a battery, and the frequency of the output voltage of the AC generator is made substantially the same as the resonance frequency of the resonance circuit, and one of the resonance circuit and the AC generator is connected to the power converter via a changeover switch. And a power converter that operates an internal semiconductor switch to convert an input voltage into a pulse train of a high-frequency AC voltage half-wave waveform to obtain a desired output voltage. The electric system of a hybrid electric vehicle. 2. The electric system of 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 a power steering, and charging an auxiliary battery. Characteristic electric system of hybrid electric vehicle. 3. The electric system for a hybrid electric vehicle according to claim 1, wherein the AC generator is a single-phase AC generator.