JP2000166225A - Electric system for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric system of an automobile, where a system unit for air-condition can be miniaturized/lightened and operation efficiency can be improved. SOLUTION: In an electric system driving the air-condition compressor of a vehicle where an on-vehicle DC power source 1 is made to be a power source, the second DC power source of voltage higher than the voltage of the first DC power source 1 is composed of the on-vehicle first DC power source 1 to a boosting chopper 10. An electric motor 4 for driving compressor is driven from the second DC power source through an inverter 3.

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 an automobile for driving a vehicle air-conditioning compressor powered by an on-board DC power supply.

[0002]

2. Description of the Related Art FIG. 8 is an electric system diagram for a vehicle air conditioner for driving a conventional vehicle air conditioner compressor. 8, 1 is a DC power supply, 2 is a main switch of the power supply, 3 is an inverter, 4 is an AC motor driving a compressor 5, 6
Indicates an air conditioning system. The air conditioning system 6 includes a refrigerant liquid circulation system 61 and air conditioners 62 such as an evaporator.
The inverter 3 is a PWM inverter, the control of which is a known technique, and a description thereof will be omitted. FIG.
FIG. 9 is a circuit configuration diagram of the inverter of FIG. 8. 31 is a semiconductor switch unit, 32 is an input voltage smoothing capacitor, 33 is an initial charging circuit of the input voltage smoothing capacitor 32, and this initial charging circuit 32 is composed of a relay 331, a diode 332, and a resistor 333.

Next, the starting of the inverter 3 will be described with reference to FIGS. When the vehicle is started, when the main switch 2 is turned on, the voltage of the DC power supply 1 is applied to the input of the inverter 3. At this time, the relay 331 of the initial charging circuit 33
Is on, the voltage of the input voltage smoothing capacitor 32 becomes about twice the voltage value of the DC power supply 1. This is because the input voltage smoothing capacitor 32 resonates with the inductance (not shown) of the wiring between the DC power supply 1 and the input voltage smoothing capacitor 32. Therefore, when the main switch 2 is turned on, the relay 331 is turned off, and the diode 33 is turned off.
Non-resonant charging is performed via the resistor 2 and the resistor 333 to charge the battery to the voltage value of the DC power supply 1, and then the relay 331 is turned on.
In addition, conventional cooling of automobile equipment is water-cooled for the engine system and air-cooled for the rest. The cooling of the inverter 3 in FIG. 8 is also water-cooled or air-cooled.

[0004]

The in-vehicle equipment of an automobile is
Small and light weight, low price, vibration resistance, and high reliability are required, and the air conditioning electric system shown in FIG. 8 has the same requirements. However, in a conventional air-conditioning electric system using a vehicle-mounted DC power supply as a power source, 1) the DC power supply is 12 V
And low. Also, it is 48 V or less at the highest. The power of the automotive air conditioning system is 1 kW or more. The input voltage of the inverter for electric vehicles and home air conditioners should be 120V or more.
The flowing current value of the equipment is reduced. On the other hand, when the input voltage of the inverter becomes 12 V, the flowing current of the device becomes 10 times as large as that of the inverter, and the loss and size of the device increase
It will be expensive. Also, mechanical relays are weak in vibration resistance. For this reason, it is desired that the power supply of the on-vehicle equipment such as an air conditioner is as high as possible and that a mechanical relay is eliminated.

[0005] 2) Water cooling or air cooling of electrical equipment.
Automotive engine cooling is water-cooled. For this reason, a water-cooled type is also used for cooling the in-vehicle equipment. Since it is engine cooling water, the maximum water temperature is about 100 ° C. On the other hand, among the in-vehicle devices, since the semiconductor element of the semiconductor power conversion device is a silicon element and the maximum operating temperature is 125 ° C., the difference between the maximum operating temperature and the cooling water temperature is small, and the cooling of the semiconductor device Parts occupy a large part of the size of the semiconductor power converter. In order to reduce the size of the in-vehicle power converter, downsizing of the cooling unit is a major issue.
On the other hand, a method of cooling a semiconductor power conversion device by providing a cooling water system separately from an engine cooling system is also adopted. In this case, the cooling water can be reduced to 100 ° C. or less, and the cooling unit of the semiconductor device can be made smaller than the above-described method. There was a limit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric system for an automobile, which can reduce the size and weight of system devices for air conditioning and improve the driving efficiency.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the fact that, if the voltage is increased, the size and efficiency of the equipment can be reduced, and the temperature of the refrigerant for air conditioning is several degrees Celsius or less. In order to solve the above-mentioned problem, the present invention provides an electric system for driving an air conditioning compressor of an automobile powered by an on-board DC power supply, wherein the first DC power supply on the vehicle is provided with a step-up chopper. And a second DC power supply having a voltage higher than the voltage of the DC power supply. The second DC power supply drives an electric motor for driving the compressor via an inverter.

In the above-mentioned electric system for an automobile, the inverter may be connected from the second DC power supply via a semiconductor switch, and the inverter may be omitted from an initial charging circuit. Furthermore, in the electric system of the vehicle, the DC input voltage value of the inverter may be varied by the boost chopper according to the size of the air conditioning load. Further, in the electric system of the automobile, the circuit component of the boost chopper and the circuit component of the inverter may be attached to a cooling plate or a common cooling plate cooled by the air-conditioning refrigerant, or the circuit of the boost chopper may be mounted. A component and a circuit component of the inverter may be directly cooled by the air-conditioning refrigerant. In the above-mentioned electric system for a vehicle, the semiconductor switch of the step-up chopper is a MOSFET.

[0009]

FIG. 1 is a circuit diagram of an electric system of an automobile showing a first embodiment of the present invention, and corresponds to the first embodiment of the present invention. 1, the same members as those of the conventional example of FIG. 8 are denoted by the same reference numerals, and the description thereof will be omitted. 1 differs from the conventional example in that a step-up chopper circuit 10 is inserted on the DC power supply side of the inverter 3. Reference numeral 11 denotes a semiconductor switch such as a MOSFET, 12 denotes a current smoothing reactor, 13 denotes a diode, 14 denotes an input capacitor, and 15 denotes an output capacitor. According to the present embodiment, a high-voltage DC power supply can be configured from the first DC power supply 1 mounted on the vehicle via the step-up chopper 10, and the second DC power supply having a higher voltage than the voltage of the first DC power supply 1 can be configured. Since the compressor driving motor 4 can be driven by the DC power source via the inverter 3, the size and efficiency of the air conditioning system equipment can be reduced.

FIG. 2 is a circuit diagram of an electric system of a vehicle according to a second embodiment of the present invention, which is an embodiment corresponding to the second and third aspects of the present invention. 2, the same members as those in FIG. 1 are denoted by the same reference numerals. 2 is different from FIG. 1 in that the inverter 3a of FIG. 1 does not include the initial charging circuit 33 on the DC side, and a booster in which a semiconductor switch 16 such as a MOSFET is newly inserted on the output side of the booster chopper 10. That is, the chopper 10a is used.

The operation of the system shown in FIG. 2 will be described with reference to FIG. FIG. 3 is an operation explanatory diagram showing an operation time chart of FIG. 2 and operation waveforms of respective parts. When the main switch 2 is turned on at time T1, the voltage of the DC power supply 1 is applied to the input of the boost chopper circuit 10a. The voltage is controlled by the aforementioned resonance operation.
It is charged to about twice the voltage value Vd of the DC power supply 1. Although the charging voltage of the output voltage smoothing capacitor 15 is about twice the voltage value of the DC power supply 1, the input voltage value of the inverter 3a (the voltage value of the input voltage smoothing capacitor 32) is at least twice the voltage value of the DC power supply 1. There is no problem. Switch 16
Is off, the inverter input voltage is zero.

Next, at time T2, the switch 16 is turned on to pressurize the input of the inverter 3a. Since the capacity of the output voltage smoothing capacitor 15 is so small as to be negligible with respect to the capacity of the input voltage smoothing capacitor 32, it becomes zero once after the switch 16 is turned on.
Is charged to a voltage of about twice the voltage value Vd of the DC power supply 1 and thereafter kept substantially constant. At time T3, the boost chopper 10a is operated (by switching the switch 11), and the output voltage of the boost chopper 10a (the inverter 3
is controlled so as to be a target value (Vs in FIG. 3). After time T4 when the input voltage of the inverter 3a reaches the target value, the inverter 3a is operated to drive the air conditioning system. Until the operation of the air conditioning system is completed, the switch 16 is turned on, and the boost chopper 10a continues to operate.
Although the above description of FIG. 3 shows the case where the switch 16 is turned on at time T2, the input voltage of the inverter 3a can be raised by switching the switch 16 (on and off).

FIG. 4 shows the operation of the inverter of the circuit system shown in FIGS. 1 to 3 and is an embodiment corresponding to claim 4 of the present invention. , And can be varied by a step-up chopper. In FIG. 4, Vin is the inverter input voltage, and N is the motor speed. Depending on the size of the air conditioning load, the motor 4 for driving the air conditioning compressor
When the power is adjusted by adjusting the rotation speed of the inverter, the input voltage of the inverter is also adjusted. As the number of revolutions control, there is a method of controlling the efficiency of the air conditioning system to be maximum, and the like. In the example shown in FIG. 4, the case where the inverter input voltage is proportional to the motor speed is shown.

FIG. 5 is a system configuration diagram of a step-up chopper and an inverter according to a third embodiment of the present invention. In FIG. 5, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals. In this embodiment, the circuit components of the step-up chopper and the circuit components of the inverter are mounted on a cooling plate cooled by a refrigerant for air conditioning. In FIG.
100 is a cooling plate of the booster chopper 10a.
At 00, a heat-generating component (for example, the semiconductor switch 11, the current smoothing reactor 12, etc.) of the step-up chopper 10a is attached. Reference numeral 300 denotes a cooling plate of the inverter 3a.
At 00, a heat-generating component (for example, a semiconductor switch unit) of the inverter 3a is attached. Each cooling plate 100, 300 has a cooling pipe 400a, 400b, 400c through which a cooling liquid passes.
Is connected to the refrigerant liquid circulating system of the air conditioning system 6.
The cooling medium of the air conditioning system 6 flows to the cooling plates 100 and 300 via the cooling pipes 400a, 400b and 400c to be cooled. Since the temperature of the refrigerant in the air conditioning system is several degrees Celsius or less, the temperature of the cooling plate is also maintained at about the same temperature.

FIG. 6 is a system configuration diagram of a step-up chopper and an inverter according to a fourth embodiment of the present invention. In the present embodiment, the circuit components of the step-up chopper and the circuit components of the inverter are mounted on a common cooling plate cooled by a refrigerant for air conditioning. 6, the cooling plate 100 of the step-up chopper 10a and the cooling plate 3 of the inverter 3a in the embodiment of FIG.
00 is integrated with the cooling pipe 400
Cooling is performed by flowing a refrigerant through d and 400e. With such a configuration, a common cooling plate and cooling piping between the cooling plates are not required, and the system can be downsized.

FIG. 7 is a system configuration diagram of a step-up chopper and an inverter according to a fifth embodiment of the present invention. In this embodiment, the circuit components of the step-up chopper and the circuit components of the inverter are directly cooled by a refrigerant for air conditioning. In the figure, the boost chopper 10 or the boost chopper 10a shown in FIGS. 1 and 2 and the circuit components of the inverter 3 or the inverter 3a are housed in a housing 500.
Is connected to the refrigerant liquid circulation system of the air conditioning system 6 via the cooling pipes 400f and 400g. A coolant flows into the housing 500 via the cooling pipes 400f and 400g, and directly cools circuit components. In the system shown in FIG. 7, since the circuit components are directly cooled by the refrigerant liquid having a temperature of several degrees C., the size of the apparatus can be significantly reduced.

Further, the semiconductor switch 11 of the boosting chopper and the semiconductor switch 16 of the boosting chopper output are MOSFETs. MOSFE
By setting T, lower loss and high frequency switching can be realized.

[0018]

As described above, according to the present invention, 1) a second DC power supply having a higher voltage than the voltage of the first DC power supply is constituted by a step-up chopper from a first DC power supply mounted on a vehicle; The motor for driving the compressor is driven from the second DC power supply via the inverter. 2) The DC input voltage value of the inverter is variably controlled by a step-up chopper according to the size of the air conditioning load. 3) The circuit components of the step-up chopper and the circuit components of the inverter are mounted on a cooling plate cooled by a refrigerant for air conditioning or a common cooling plate. 4) The circuit components of the step-up chopper and the inverter are directly cooled by the refrigerant liquid for air conditioning. 5) The semiconductor switch of the step-up chopper is changed to a MOSFET for high-frequency switching. This has the following effects. 1) It is possible to significantly reduce the size, weight, and cost of air conditioning system equipment. 2) The operation efficiency of the air conditioning system can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of an electric system of a vehicle showing a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of an electric system of a vehicle according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating the operation of FIG. 2;

FIG. 4 is a diagram illustrating the operation of FIGS. 1 and 2;

FIG. 5 is a system configuration diagram of a boost chopper and an inverter showing a third embodiment of the present invention.

FIG. 6 is a system configuration diagram of a boost chopper and an inverter according to a fourth embodiment of the present invention.

FIG. 7 is a system configuration diagram of a boost chopper and an inverter according to a fifth embodiment of the present invention.

FIG. 8 is a diagram of a conventional electric system for vehicle air conditioning.

FIG. 9 is a circuit configuration diagram of the inverter of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Main switch 3 Inverter 3a Inverter 4 Compressor drive motor 5 Air conditioning compressor 6 Air conditioning system 10 Booster chopper 10a Booster chopper 11 Semiconductor switch 16 Semiconductor switch 32 Initial charging circuit 100 Cooling plate 100a Common cooling plate 300 Cooling plate

Continued on the front page. (72) Inventor Toshiharu Watanabe 7-3, Sakaemachi, Sano-shi, Tochigi Prefecture, Calsonic Co., Ltd. (72) Inventor Koichi Ueki 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. F-term (reference) 5H730 AA15 AS13 BB14 DD04 ZZ07 ZZ11

Claims (8)

[Claims] 1. An electric system for driving an air conditioner compressor of an automobile powered by an on-board DC power supply, wherein a voltage higher than the voltage of the first DC power supply is supplied from a first DC power supply on the vehicle by a step-up chopper. An electric system for an automobile, wherein the second DC power supply is configured to drive a compressor driving motor via an inverter from the second DC power supply. 2. The electric system according to claim 1, wherein the inverter is connected to the second DC power supply via a semiconductor switch. 3. An electric system according to claim 2, wherein said inverter does not include an initial charging circuit. 4. The electric vehicle according to claim 1, wherein a DC input voltage value of said inverter is varied by said step-up chopper in accordance with a load of an air conditioner. system. 5. The method according to claim 1, wherein the circuit components of the step-up chopper and the circuit components of the inverter are respectively mounted on a cooling plate cooled by the air-conditioning refrigerant. And the electrical system of the car. 6. The method according to claim 1, wherein the circuit components of the step-up chopper and the circuit components of the inverter are mounted on a common cooling plate cooled by the air-conditioning refrigerant. And the electrical system of the car. 7. The electric vehicle according to claim 1, wherein the circuit components of the step-up chopper and the circuit components of the inverter are directly cooled by the air-conditioning refrigerant. system. 8. An electric system for an automobile according to claim 1, wherein said semiconductor switch of said step-up chopper is a MOSFET.