JP2000289452A - Air conditioner for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an abnormal overheat caused by the short circuit accident of a capacitor by forming the current-carrying device of an electric compressor drive device with a transistor, a Zener diode and first and second resistors, and providing a constant-current function charging the capacitor at a constant current. SOLUTION: The voltage of a battery 2 is applied to the collector of an output transistor(Tr) 9 and a base resistor 14 via a fuse 10, and the base current of the output Tr 9 flows to a capacitor 11. An emitter current and the base current flow in an emitter resistor 16 to generate a voltage which is (+) on the collector side of the output Tr 9 and is (-) on the capacitor 11 side. When this voltage exceeds the sum of the voltage between the base and emitter of a control Tr 13 and the Zener voltage of a Zener diode 12, the base current of the control Tr 13 flows, however the base voltage of the output Tr 9 is reduced by the voltage of the product of the collector current of the control Tr 13 and the resistance value of the base resistor 14, and the circuit operation is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for an electric vehicle having an electric compressor driven by electric power from a battery.

[0002]

2. Description of the Related Art In an electric vehicle air conditioner, an electric compressor driving device for driving an electric compressor for air conditioning supplies a large current to the electric compressor.
Also, the large fluctuation of the current affects the durability of the battery supplying the current. Therefore, as shown in the voltage / current waveform diagram of FIG. 3, it is necessary to smooth the current supplied to the electric compressor to suppress electric noise and current fluctuation. For this purpose, a condenser having a large capacitance is provided at a position where the electric compressor driving device is supplied with electric power from a battery via a switching device.

However, when a capacitor having a large capacitance is provided, a large charging current flows to the capacitor at the moment when the battery is connected. For this reason, there are problems such as a blown fuse or a surge voltage generated by resonance with an inductance component such as a wiring from a battery as shown in the voltage / current waveform diagram of FIG. 3 to damage the electric compressor driving device.

[0004] Therefore, in order to suppress the charging inrush current to the capacitor at the moment when the battery is connected, the battery is charged through the power supply device. And usually, a resistor is used as an energizing device.

However, when a resistor is used as a current-carrying device, the battery usually has a high voltage of about 300 V, and the capacitor has a large capacity of about 1000 microF. Must use high power products to maintain its reliability.
And that value is around 60W.

[0006]

As described above, when a resistor is used as a current-carrying device, a high-power product of about 60 W must be used. Since this large power resistor has a large shape, it cannot be directly connected to a printed circuit board in the electric compressor drive device, and a considerable space for mounting the space must be secured. As an air conditioner for an electric vehicle, the air conditioner must be installed in a limited space of the vehicle, so the air conditioner must be made as small as possible. Therefore, an energizing device that does not increase the size of the air conditioner is required.

When a resistor is used as an energizing device, a wire for the resistor is required, and the wire is fixed so that the wire is not damaged by touching a heating element or a metal edge. There is a need to. Therefore, the structure as an energization device becomes complicated, so that it becomes large and difficult to manufacture.

Further, the resistance value of the resistor must be large enough to suppress the charging inrush current. On the other hand, in the event of a failure such as a failure of the electric compressor drive unit or a short circuit in the condenser, the fuse must be small enough to blow.

Therefore, the resistance value of the resistor needs to be changed according to the battery voltage and the capacitance value of the capacitor.

[0010] However, there are many types of battery voltages of electric vehicles, and the required capacity of the air conditioner differs depending on the vehicle, so that the current supplied to the electric compressor also differs.

Therefore, the resistance value of the resistor needs to be changed depending on the air conditioner and the vehicle, and the type of the air conditioner increases, so that the production management becomes complicated, causing problems such as a production trouble and an increase in cost.

[0012] In addition, in the event of a semi-failure of the electric compressor driving device, the capacitor, or the like where the fuse cannot be blown, a large amount of power is consumed by the resistor, and the reliability is reduced due to overheating. Therefore, the air conditioner becomes large due to heat dissipation measures and the like.

Accordingly, the present invention provides a compact, simple structure,
It is an object of the present invention to provide a highly reliable and common electric vehicle air conditioner.

[0014]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a DC power supply, an energizing device connected in series to the DC power source, a switchgear connected in parallel with the energizing device, and a DC power supply. A condenser that is charged from a power supply through an energizing device, an electric compressor drive that is supplied with electric power from a DC power supply through a switching device, and drives an electric compressor for air conditioning, and a heat generated in the electric compressor drive. In an automotive air conditioner having a radiator for radiating heat and a printed circuit board constituting a part of an electric circuit of an electric compressor driving device, an energizing device includes a transistor, a Zener diode, a first resistor, 2
At least, the transistor is an NPN transistor, and has a constant current function of charging the capacitor with a constant current, and the constant current value can operate even when the capacitor is short-circuited. With the current value, the transistor is fixed to the radiator, and the heat generated by the transistor is radiated to the radiator, and the collector, base, and emitter terminals of the transistor are directly electrically connected to the printed circuit board.

[0015]

According to the present invention, the power supply device charges the capacitor with a constant current. By setting the constant current value to a small value so that the constant current function can operate even if the capacitor is short-circuited, the current will be constant even when the electric compressor drive unit is damaged or the capacitor is short-circuited. Since the value is held at the value, even if the fuse is not blown, the heat generated in the transistor is radiated to the radiator, so that abnormal overheating can be prevented.

Even when the capacitor is short-circuited,
Since the constant current function is operable, the capacitor can be charged over a long time no matter how large the capacitance value of the capacitor is.
Thus, a common energizing device can be used regardless of the capacitance value of the capacitor. Even if the capacitor is short-circuited at the highest voltage of the DC power supply, if the constant current function is operable, a common power supply device can be used regardless of the DC power supply voltage.

Further, by configuring the energizing device with a transistor and setting the constant current value small, a small transistor can be used, and the energizing device can be directly connected to a printed circuit board in the electric compressor driving device. In addition to the transistor, the Zener diode, the first resistor, and the second resistor only need a few parts, and the radiator for the transistor shares the radiator for the electric compressor drive. do not do.

Therefore, a large space is not required, and the air conditioner can be downsized.

Further, the collector and base of the transistor,
Since each terminal of the emitter is directly connected to the printed circuit board, wiring using lead wires is not required, so wiring fixing work to prevent damage by touching the heating element, metal edge, etc. is unnecessary. . Therefore, the structure as the current-carrying device is simplified, and the manufacturing is facilitated.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 shows a circuit diagram of an air conditioner for an electric vehicle according to an embodiment of the present invention.

FIG. 5 is different from the circuit diagram of the conventional air conditioner for an electric vehicle in that the current supply device is different and the conventional example is a resistor, whereas the embodiment of the present invention is a constant current circuit. , Output transistor 9, control transistor 13,
It comprises a Zener diode 12, a base resistor A / 14, a base resistor B / 15, and an emitter resistor 16.

Here, the operation of the circuit will be described.

When the battery 2 is connected, the fuse 1
A voltage is applied to the collector of the output transistor 9 and the base resistor A. Since a voltage is applied to the base of the output transistor 9 via the base resistor A.14, the base current is changed from the emitter to the emitter resistor 1
6 flows to the condenser 11. Therefore, an emitter current commensurate with the current amplification factor from the collector to the emitter of the output transistor 9 tends to flow from the emitter to the capacitor 11 via the emitter resistor 16.
Therefore, the emitter current and the base current flow through the emitter resistor 16, and a positive voltage is generated on the collector side of the output transistor 9 and a negative voltage is generated on the capacitor 11 side. At both ends of the emitter resistor 16, from the plus side of the voltage to the base resistor B · 15, the base of the control transistor 13, the emitter of the control transistor 13, the cathode of the Zener diode 12, the anode of the Zener diode 12, and the minus side of the voltage Is connected to

Therefore, the above voltage is applied to the control transistor 1
3 base-emitter voltage and Zener diode 1
When the sum exceeds the sum of the Zener voltage of 2 and the base resistance B · 1
5. The base current of the control transistor 13 flows to the base of the control transistor 13, the emitter of the control transistor 13, the cathode of the Zener diode 12, and the anode of the Zener diode 12. As a result, the collector current of the control transistor 13 is increased through the battery 2, the fuse 10, the base resistance A.14, the collector of the control transistor 13, and the control transistor 13
, The cathode of the Zener diode 12, the anode of the Zener diode 12, and the capacitor 11. Therefore, this collector current and the base resistance A · 1
Since the base voltage of the output transistor 9 is reduced by the voltage obtained by multiplying the resistance value of the output transistor 4 with the resistance value of 4, the base current is reduced, and the emitter current is also reduced.

Therefore, the voltage across the emitter resistor 16 is reduced. This also reduces the base current of the control transistor 13 and the collector current,
The base voltage of the output transistor 9 increases, the base current of the output transistor 9 increases, the emitter current also increases, and the voltage across the emitter resistor 16 increases.

As described above, the circuit operation is stabilized in a state where the voltage across the emitter resistor 16 matches the sum of the base-emitter voltage of the control transistor 13 and the Zener voltage of the Zener diode 12.

Therefore, the emitter current is a value obtained by dividing the sum of the base-emitter voltage of the control transistor 13 and the Zener voltage of the Zener diode 12 by the resistance value of the emitter resistor 16 (more precisely, the base resistor B · 15). Voltage).

Since the base-emitter voltage, the Zener voltage and the resistance value are fixed values, the above calculated values are fixed values, that is, constant currents.

The above operation is shown in a circuit operation diagram according to the embodiment of the present invention in FIG.

The voltage Vc of the capacitor 11 is zero at the start when the battery 2 is connected, but rises linearly because it is charged at a constant current. Output transistor 9
Since a constant current flows through the emitter resistor 16 from the start, the emitter voltage Ve of the
The sum is the sum of the emitter-to-emitter voltage and the zener voltage, and thereafter becomes the sum of the voltage Vc of the capacitor 11 and the sum of the base-emitter voltage and the zener voltage.

The voltage Vr across the emitter resistor 16 is the sum of the base-emitter voltage and the Zener voltage from the start.

The collector-emitter voltage Vce of the output transistor 9 becomes a voltage obtained by subtracting the emitter voltage Ve of the output transistor 9 from the voltage E of the battery 2.
Decreases linearly.

The emitter current Ie of the output transistor 9
Indicates that the voltage Vr across the emitter resistor 16 is
6 is a fixed value divided by the resistance value.

The collector loss Pc of the output transistor 9
Are the collector-emitter voltage Vce and the emitter current I
e, the collector-emitter voltage Vce decreases linearly, and the emitter current Ie is a fixed value.
Decreases linearly.

In the above description, the control transistor 13 is used, but the control transistor 13 is not used.
Even if the cathode of the Zener diode 12 is connected to the base of the output transistor 9, a constant current circuit can be achieved. In this case, the sum of the base-emitter voltage of the output transistor 9 and the voltage across the emitter resistor 16 is equal to the Zener voltage of the Zener diode 12. Since the base-emitter voltage of the output transistor 9 and the Zener voltage of the Zener diode 12 are constant, the emitter resistance 16
Also has a constant value. Therefore, the current flowing through the resistor 16 has a constant value.

Here, the operation of the circuit diagram of the conventional air conditioner for electric vehicles will be described with reference to the circuit diagram of the air conditioner for conventional electric vehicles in FIG. 5 and the circuit operation diagram of the air conditioner for conventional electric vehicles in FIG. I do.

When the battery 2 is connected, the voltage Vc of the capacitor 11 and the voltage of the resistor 8 are determined by a time constant determined by the resistance of the resistor 8 and the capacitance of the capacitor 11.
And the current Ic of the capacitor 11 are determined as shown in FIG.

When the capacitor 11 is charged and the input voltage detecting means 7 detects a voltage equal to or higher than a predetermined value, the control unit 6 closes the switchgear 3 and power is supplied from the battery via the switchgear, and the electric compressor drive unit Drives the electric compressor for air conditioning.

As described above, the resistance value of the resistor 8 must be large enough to suppress the charging rush current. On the other hand, in the event of a failure such as a failure of the electric compressor drive unit or a short circuit in the condenser, the fuse must be small enough to blow. Also, the fuse value must not be blown at normal operating current,
It is about 10A. Therefore, at the time of failure, it is necessary to make the current of about 40 A flow in order to surely blow the fuse.
Ohm. Therefore, when battery 2 is connected, 40
About A flows and thereafter is determined by the time constant. As the capacitance value of the capacitor 11 increases, the time constant increases and the power consumption of the resistor 8 increases. The capacitance value of the capacitor 11 is usually a large value of about 1000 μF for current smoothing. When the battery 2 is connected, the instantaneous maximum power consumption is 300 V × 40 A = 12000 W.

Therefore, a high-power resistor must be used for the resistor 8 in order to maintain its reliability. The value is a rated product of about 60 W according to the guaranteed specifications of the resistor 8.

As shown in FIG. 4, even if two 30W resistors are used instead of 60W, a large space is required as a controller of a vehicle air conditioner.

Further, in the case of a semi-failure of the electric compressor driving device, the condenser, etc., in which the fuse is not blown,
For example, when a current of 9 A (a fuse rating of 10 A or less) flows, the resistor 8 is (9 A) 2 × 7.5 ohm = 607.5.
W consumes a large amount of power, and causes a reduction in reliability such as smoke, solder melting, and wiring damage due to overheating. Therefore, a radiator or the like for heat dissipation is required, which results in an increase in size.

On the other hand, in the case of the constant current charging, the operation is performed in the same manner as described above. However, the capacitor 11 is charged by the resistor 8
Instead, it is performed by the current supply device 4 having a constant current.

The constant current value is a value obtained by dividing the sum of the base-emitter voltage of the control transistor 13 and the Zener voltage of the Zener diode 12 by the resistance value of the emitter resistor 16.
The resistance value of the emitter resistor 16 can be arbitrarily set by appropriately selecting the resistance value. If the Zener voltage is 6 V and the resistance value is 70 ohms (base-emitter voltage is 1 V), 0.1
A. Therefore, from the point of connection of the battery 2, only a current 0.1A, which is much smaller than the conventional 40A, flows. The power consumption of the emitter resistor 16 is 0.7 W, and a 1 W resistor may be used, which is much smaller than the conventional 60 W resistor. In the event of a failure such as a failure of the electric compressor drive unit or a short circuit in the capacitor, the current is 0.1A even in the case of a semi-failure, so the fuse will not blow. is there. It is much smaller than the conventional 607.5w.

Therefore, if the output transistor 9 is attached to the heat sink 19 for the output section 18 as shown in FIG. The heat sink 19 is for the output section 18 that generates heat of several tens of watts, and can sufficiently cope with 30 W of the output transistor.
Therefore, even when the capacitor is short-circuited to which the maximum voltage of 300 V is applied, there is no abnormality in the circuit, and the constant current can be supplied.

Further, since the constant current value is small, a small transistor can be used and can be directly connected on a printed circuit board. Therefore, a large space is not required, and the air conditioner can be downsized. Further, since there is no wiring, wiring fixing work is not required, and manufacturing becomes easy. Further, since the constant current value is determined by the above-described circuit regardless of the battery voltage and the capacitance value of the capacitor, a common energizing device can be used.

In the embodiment of the present invention, by providing a switch in series with the base resistor A.14, the base current of the output transistor 9 is turned off by opening and closing the switch.
F · ON to reduce the emitter current of the output transistor 9 to O
It can be turned on and off. Therefore, when a failure such as a failure of the electric compressor drive device or a short circuit of the capacitor occurs, it is possible to detect an abnormality and to turn off the emitter current of the output transistor 9 by detecting the conduction time of the emitter current including a half failure. The base current is smaller than the emitter current of 0.1 A and is about 0.01 A, and does not require a large switch.

On the other hand, the conventional circuit has a maximum of 300 V, 40 V
Since the opening and closing of A is required, a large switch is required, and a large space and cost are required.

Although the switching device is a relay in the above embodiment, it can be realized by a transistor, a thyristor or the like.

[0051]

According to the present invention, when charging a capacitor with a constant current, the energizing device sets the constant current value to a small value so that the constant current function can operate even when the capacitor is short-circuited. In case of failure such as electric compressor drive breakage, capacitor short circuit, etc., the current is kept at a constant current value even in the case of semi-failure, so even if the fuse does not blow, the heat generated by the transistor is radiated to the radiator Overheating can be prevented.

Even if the capacitor is short-circuited,
Since the constant current function is operable, the capacitor can be charged over a long time no matter how large the capacitance value of the capacitor is.
Thus, a common energizing device can be used regardless of the capacitance value of the capacitor. Even if the capacitor is short-circuited at the highest voltage of the DC power supply, if the constant current function is operable, a common power supply device can be used regardless of the DC power supply voltage.

Further, by configuring the energizing device with a transistor and setting the constant current value small, a small transistor can be used, and the energizing device can be directly connected to a printed circuit board in the electric compressor driving device. In addition to the transistor, the Zener diode, the first resistor, and the second resistor only need a few parts, and the radiator for the transistor shares the radiator for the electric compressor drive. do not do.

Therefore, a large space is not required, and the air conditioner can be downsized.

Further, the collector and base of the transistor,
Since each terminal of the emitter is directly connected to the printed circuit board, wiring using lead wires is not required, so wiring fixing work to prevent damage by touching the heating element, metal edge, etc. is unnecessary. . Therefore, the structure as the current-carrying device is simplified, and the manufacturing is facilitated.

In the event of a failure such as a failure of the electric compressor driving device or a short circuit of the capacitor, the output transistor 9 is detected by detecting an abnormality by detecting the duration of the emitter current.
Can be turned off. The base current is even smaller than the small value emitter current and does not require a large switch.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an air conditioner for an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a circuit operation diagram according to an embodiment of the present invention.

FIG. 3 is a voltage / current waveform diagram of the same.

FIG. 4 is a perspective view showing a resistor / transistor shape.

FIG. 5 is a circuit diagram of a conventional electric vehicle air conditioner.

FIG. 6 is a circuit operation diagram of a conventional air conditioner for an electric vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric compressor drive device 2 Battery 3 Switching device 4 Electric conduction device 5 Electric compressor 6 Control part 7 Input voltage detecting means 8 Resistor 9 Output transistor 10 Fuse 11 Capacitor 12 Zener diode 13 Control transistor 14 Base resistance A 15 Base resistance B 16 Emitter Resistance 18 Output unit 19 Heat sink 20 Printed circuit board 21 Wiring

Claims (1)

[Claims] A DC power supply; an energizing device connected in series with the DC power source; a switching device connected in parallel with the energizing device; and a capacitor charged from the DC power source via the energizing device. An electric compressor driving device that is supplied with electric power from the DC power supply via the switching device and drives an electric compressor for air conditioning; a radiator that radiates heat generated in the electric compressor driving device; and the electric compressor. An air conditioner for a vehicle, comprising a printed circuit board constituting a part of an electric circuit of a driving device, wherein the energizing device includes at least an NPN transistor, a Zener diode, a first resistor, and a second resistor. The capacitor is charged at a constant current with a predetermined current value operable even when the capacitor is short-circuited. An automotive air conditioner having a constant current function, wherein the NPN transistor is fixed to the radiator, and each terminal of the NPN transistor is electrically connected to the printed circuit board.