JP2988713B2 - Control method of air conditioner for electric vehicle - Google Patents

Description

The present invention relates to a method for controlling an air conditioner for an electric vehicle mounted on an electric vehicle, and more particularly to a method for controlling a compressor using a battery as a power source. The present invention relates to a method for controlling an air conditioner for an electric vehicle in which the rotation speed is variably controlled by an inverter.

(Prior Art) An electric vehicle is equipped with, for example, a heat pump type inverter air conditioner as an air conditioner. This inverter air conditioner is configured as shown in FIG. 2 and has an outdoor heat exchanger in an engine room below a hood. 1 is arranged. Between the outdoor heat exchanger 1 and an indoor heat exchanger 3 disposed in a blower room from an indoor blower 2 communicating with an operator's cab (vehicle compartment), a compressor unit 4 having a compressor powered by a battery is provided. A refrigeration cycle is configured by intervening, and an inverter of an inverter unit 8 is driven via a relay unit 6 and a control unit 7 by an operation of an operation panel 5 provided in a driver's seat, and the rotation speed of the compressor is controlled by the inverter. Is variably controlled.

Here, the heat exchange characteristic of the outdoor heat exchanger 1, that is, the relation of the heat exchange rate K of the outdoor heat exchanger 1 with respect to the traveling speed V of the vehicle, as shown in FIG. The ratio K is proportional, and when the traveling speed V increases with respect to the stop time, the amount of air blown into the outdoor heat exchanger 1 increases and the amount of heat exchange increases.

Further, as shown in FIG. 4, the compressor operating current A and the condenser pressure P at the compressor operating frequency Hz ₁ are obtained.
The relation curve between d and the traveling speed V of the vehicle is a and b
As shown in (1), when the traveling speed V increases, both the compressor operating current A and the condenser pressure Pd decrease.

Conventionally, the outdoor heat exchanger 1
Despite having such heat exchange characteristics as above, there is generally no mechanism provided to vary the maximum value of the operating frequency of the compressor in accordance with the change in the traveling speed V of the vehicle. The operation is controlled so that the operating frequency of the compressor is always constant irrespective of the traveling speed and the traveling speed V of the vehicle.

(Problems to be Solved by the Invention) However, in the conventional air conditioner for an electric vehicle, as shown in FIG. Since the amount of air passing through the outdoor heat exchanger 1 differs between large and small, the amount of heat exchange in the outdoor heat exchanger 1 during traveling is larger than when stopped, and the amount of heat exchange increases as the traveling speed V increases.

Considering this heat exchange characteristic during the cooling operation, as shown in FIG. 4, when the operating frequency of the compressor is the same, the condenser pressure Pd when the vehicle is stopped, which is not affected by the traveling wind, is higher than the traveling pressure. It becomes higher than that at the time of traveling affected by the wind, and the traveling air flow increases as the traveling speed V increases, so that the heat exchange amount increases and the condenser pressure Pd decreases. As a result, the compressor operation current A also becomes maximum when the vehicle is stopped, and the capacity of the large-capacity transistor (GTr) for controlling the waveform of the inverter needs to be large on the basis of the vehicle stop. For this reason, the capacity of the inverter circuit at the time of stopping and at the time of low speed becomes large, and there is a problem that it is not preferable in terms of cost and reliability.

The present invention has been made in consideration of the above-described circumstances, and suppresses the compressor operating current from a stop of a vehicle to a low speed as much as possible so that the capacity of an inverter circuit can be reduced. An object of the present invention is to provide a control method for a harmony machine.

[Configuration of the invention]

(Means for Solving the Problems) A method for controlling an air conditioner for an electric vehicle according to the present invention includes:
In a control method of an air conditioner for an electric vehicle, wherein the rotation speed of a compressor of the air conditioner mounted on the electric vehicle and powered by a battery is variably controlled by an inverter, the running speed of the vehicle increases with the maximum value of the operating frequency of the compressor. This is a control method in which the maximum value of the compressor operating frequency when the vehicle is stopped is set lower than when the vehicle is running, while the control is performed so as to gradually increase as the vehicle travels.

(Operation) According to the control method of the air conditioner for an electric vehicle according to the present invention, the maximum value of the operating frequency of the compressor is controlled so as to gradually increase as the traveling speed of the vehicle increases, while the control during the stop of the vehicle is performed. By setting the maximum value of the compressor operating frequency lower than the running value, the maximum value of the compressor operating current is controlled to be almost flat regardless of the running speed from stop to running, and regardless of the running speed, to keep this as low as possible. be able to.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG.

The present invention is applied to an air conditioner mounted on an electric vehicle, and the air conditioner has a configuration shown in FIG. In this air conditioner, the maximum value of the operating frequency of the compressor is particularly controlled. The characteristic of the outdoor heat exchanger 1 is shown in FIG. K is proportional to the heat exchange characteristic, and when the traveling speed V increases with respect to the stop time, the amount of air blown into the outdoor heat exchanger 1 increases and the amount of heat exchange increases.

Then, the air conditioner operates the compressor with its operating frequency at the maximum value at the time of starting or at the time of maximum load.
Further, the compressor is variably controlled so as to gradually increase as the traveling speed V increases in accordance with the magnitude of the traveling speed V. As shown in FIG. 1, the operating frequency of the compressor when the vehicle is stopped (V = 0) The maximum value is set lower than when traveling. FIG. 1 shows an example in which the operating frequency (Hz) of the compressor is continuously increased according to the traveling speed V of the vehicle, but the operating frequency of the compressor is increased stepwise according to the traveling speed V of the vehicle. You may do so. For example, a configuration may be adopted in which the operating frequency of the compressor is increased in two, three, or four or more stages in accordance with an increase in the traveling speed V of the vehicle.

In this embodiment, the maximum value (Ma
xHz) is variably set so as to gradually or continuously increase as the running speed V of the vehicle increases as shown by a frequency change curve (C) in FIG. , As shown by the solid line d in FIG.
The maximum value of the compressor operating current A can be suppressed to a constant value.

On the other hand, when the maximum value of the operating frequency A of the compressor is made constant as in the conventional example, as indicated by the one-dot chain line e in FIG. ) Is ΔA
Therefore, a large-capacity GTr is required.

Therefore, the circuit capacity for ΔA can be reduced,
As a result, the inverter circuit can be made compact, and the capacity of GTr can be reduced, thereby providing advantages in terms of cost and reliability.

〔The invention's effect〕

The control method of the air conditioner for an electric vehicle according to the present invention includes:
As described above, the maximum value of the compressor operating frequency is controlled so as to gradually increase as the traveling speed of the vehicle increases, while the maximum value of the compressor operation frequency when the vehicle is stopped is set lower than that during traveling. As a result, the maximum value of the compressor operation current can be controlled almost flat regardless of the speed of the vehicle from when the vehicle is stopped to when the vehicle is running, and furthermore, regardless of the traveling speed, thereby eliminating the need for a large-capacity transistor in the inverter circuit and the transistor capacity. Has been achieved, and the inverter circuit can be made more compact, which has the effect of reducing costs and improving reliability.

[Brief description of the drawings]

FIG. 1 shows a running speed (V) of a vehicle and a maximum value (MaxHz) of an operating frequency of a compressor according to an embodiment of the present invention.
And FIG. 2 is a plan view showing a schematic configuration of an air conditioner for an electric vehicle, and FIG. 3 is a plan view showing a traveling speed (V) and an outdoor heat exchanger. FIG. 4 shows the relationship with the heat exchange rate (K). FIG. 4 shows the traveling speed (V) when the operating frequency of the compressor is fixed.
And compressor operating current (A) and condenser pressure (P
It is a figure which shows the relationship with d). 1 ... outdoor heat exchanger, 3 ... outdoor heat exchanger, 4 ... compressor unit, 8 ... inverter unit.

Claims (1)

(57) [Claims] 1. A method for controlling an air conditioner for an electric vehicle, wherein the rotation speed of a compressor of an air conditioner mounted on the electric vehicle and powered by a battery is variably controlled by an inverter. A method for controlling an air conditioner for an electric vehicle, characterized in that control is performed such that the maximum value of the compressor operating frequency when the vehicle is stopped is set lower than when the vehicle is running, while controlling so that the running speed gradually increases as the running speed of the vehicle increases.