JPH01273719A - Driving control device for vehicle air conditioning compressor - Google Patents

Abstract

PURPOSE:To simplify a control part in its constitution by detecting an AC motor for its loaded condition and outputting an external signal, corresponding to a load, to an output voltage changing means of a generator, in case of the captioned device using the AC motor controlled by an inverter. CONSTITUTION:An AC motor 5 is detected for its loaded condition by a load condition detecting means (current transformer) 7, and its detection current is input to a control circuit 8. The control circuit 8 actuates an inverter 4 so as to generate an output by a frequency, instructed from a frequency setter 9, while outputs external signals 8a, 8b to a voltage changing circuit 2 so as to change ratio V/f (ratio of voltage V to frequency f) in accordance with a loaded condition. For instance, when a motor load decreases, the external signal 8b is output to set the output voltage to a low level. In this way, excitation of a field coil in a generator 1 is controlled in accordance with the load. By this constitution, a control part enables its constitution to be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive control device for a vehicle air conditioning compressor, and more particularly to a drive control device for driving an air conditioning compressor by an electric motor controlled by an inverter.

[Prior Art] Conventionally, an air conditioning compressor for a vehicle is driven by being directly connected to an engine, and sufficient cooling capacity cannot be obtained when the engine speed is low.

On the other hand, when the engine speed is high, the electromagnetic clutch is appropriately connected/disconnected to maintain proper cooling capacity. There is a problem in that sudden changes cause discomfort to passengers.

Therefore, it may be possible to solve the above-mentioned problems by driving the air-conditioning compressor with an electric motor controlled by an inverter. The equipment in this case is as shown in Figure 6, including a three-phase AC generator 1 rotated by the engine, a rectifier 3 that rectifies the output of the generator 1, and a rectified DC output at a predetermined frequency. The motor is comprised of an inverter 4 that converts the AC output into an AC output, and a three-phase AC motor 5 that receives the AC output and drives a compressor 6.

In this case, the conversion in the inverter 4 is as shown in FIG.
As shown in , within the period corresponding to the frequency] 0,
The input DC voltage E is set in advance as an ON time sequence B1,
This is done by chopping at B2, . The ratio V/f is always kept constant.

By the way, it is known that the drive efficiency of the above-mentioned AC motor is improved by increasing V/f as the motor load increases. The publication proposes an air conditioner in which a plurality of ■/f patterns are selected depending on the magnitude of the motor load.

In addition, after rectifying the generator output rotated by the engine,
JP-A No. 59, 1982, used an inverter to convert the power into an air conditioning power source.
It is described in the publication No.-156858.

[Problems to be Solved by the Invention] In the air conditioner proposed above, it is necessary to store a large amount of ON time sequence data in order to set a plurality of V/f patterns, or it is necessary to store ON time sequence data according to the motor load. This requires computation to correct the data, which increases the burden on the control section.

In addition, in order to prevent the generation of harmonics, it is desirable to use a specific combination of the ON time series data, but 0
In the above method of changing 8 hours, there was a problem that the ON time series data did not have a desirable combination.

The present invention solves this problem by simply storing one series of ON time sequence data of a desirable combination that does not generate harmonics, eliminating the need to store or calculate a large number of ON time sequence data. It is an object of the present invention to provide a drive control device for a vehicle air conditioning compressor, which allows the configuration of a control section to be inexpensive and simple.

[Means for Solving the Problems] The 11-section motion control device of the present invention includes a generator 1 having a rotating field coil connected to a vehicle engine, and controlling the excitation of the field coil to control the generator. a voltage changing means 2 for changing the output voltage of 1 according to an external signal; a rectifier 3 for rectifying the voltage mentioned in 1 and converting it into a DC voltage; and converting the DC voltage to an AC voltage of a predetermined frequency. an AC motor 5 that is rotated by the AC voltage of the inverter 4 and operates the air conditioning compressor 6; a means 7 for detecting the load state of the AC motor 5; and a means 7 for detecting the load state of the AC motor 5. The control means 8 is provided for applying a -F distribution part signal to the voltage changing means 2 in accordance with the voltage change means 2.

[Operation] When the load of the AC motor changes, the control means issues an external signal in accordance with the detected load condition, and changes the generator output voltage via the voltage change means. As a result, the DC voltage applied to the inverter is increased or decreased, and the AC output of the inverter is controlled to be set to the optimum voltage-frequency ratio V/f according to the motor load.

In this way, it is possible to set the optimum V/f pattern according to the motor load by simply storing single ON time sequence data in the control means within a range that does not generate harmonics.

[Embodiment] FIG. 1 shows an overall block diagram of a drive control device. In the figure, 1. 2 is a generator, 2 is a voltage changing circuit, and 3 is a J flow device.The details of these components 1 will be explained with reference to FIG.

The voltage changing circuit 2 and the rectifier 3 are integrally provided in the generator ml, and the generator 1 includes a field coil 11 that is connected to a vehicle engine and rotates, and an armature coil 1 that generates an AC power output.
It has 2. The rectifier 3 is a three-phase high wave rectifier having a plurality of rectifying diodes, and converts the generated output into direct current and outputs it from the B terminal.

Voltage change circuit 2 consists of 1 to transistor 21, 22, resistor 23
．． 24, a Zener diode 25, etc., and the transistor 21 controls the excitation of the field field 11. For the Zener diode 25, see 2.B.
A variable resistance section 26 is connected between the terminal and the excitation of the field coil 11 is controlled by 0N-OF17 so as to maintain the DC output voltage E of the B terminal fed back through the variable resistance section 26 at a predetermined value. be done.

Here, when the resistance value of the variable resistor section 26 is increased, the output voltage tL is changed to a higher value than the output voltage IE4 and is maintained. Note that the IC terminal is connected to the vehicle battery via an ignition switch (concave path).

As shown in FIG.
The transistors 264 and 265 are configured to selectively short-circuit the transistors 264 and 265, and each of the transistors 264 and 265 is activated by external signals 8a and 8b to change the resistance value in three stages.

In FIG. 1, 4 is an inverter, and the rectifier 3
As described above, this is converted into an AC voltage (2) of a desired frequency by chopping it at a predetermined ON time sequence within a specified frequency period. The AC voltage (■) is supplied to a three-phase AC motor 5 that rotationally drives an air conditioning compressor 6. A current transformer 7 as a load state detecting means is installed in one phase of the output line of the inverter 4, and detects the current in the output line that increases as the load of the AC motor 5 increases.

A control circuit 8 operates the inverter 4 so as to generate an output at a frequency instructed by the frequency setter 9. The control circuit 8 detects the load condition of the AC motor 5 from the output signal of the current transformer 7, and outputs the external signals 8a and 8b to change the V/f ratio accordingly.

The frequency setter 9 is, for example, an air conditioning computer, and inputs information such as set air conditioning temperature and internal and external temperatures, and sends a frequency command signal 9a to the control circuit 8 in order to change the rotation speed of the air conditioning compressor 6. emanate.

In a drive control device having such a configuration, when the AC motor is in a normal load state, the output line current is 111 and I21 in Fig. 4.
In this state, the external signal 8a is emitted,
The DC output voltage E of the rectifier 3 is maintained at El. Therefore, in this case, the V/f ratio becomes a constant value as shown by line A in FIG. 5, regardless of changes in frequency f.

When the motor load decreases and the output line current becomes less than Ill, an external signal 8b is generated in place of the external signal 8a,
The output voltage is maintained at the lower voltage E2. As a result, the V/f ratio becomes small as shown by line B in FIG.

Conversely, when the motor load increases and the output line current exceeds I21, the external signals 8a, 8b are canceled and the output voltage is maintained at the higher voltage E3. However,
(2) The /f ratio increases as shown by line C in FIG.

As described above, according to the drive control device of the present invention, a single O
It only has N time series data, and V depends on the motor load.
The lf ratio can be changed in three stages, and efficient motor drive is possible without requiring a large memory area for data storage or complicated correction calculations.

In the above embodiment, 1 is slightly larger than I11.
12 and I22, which is slightly smaller than I21, are provided with hysteresis to stabilize the control.

In the above embodiment, the DC output voltage was changed in three steps, but better motor drive characteristics can be obtained by changing it in multiple steps.

Further, the load condition of the AC motor can also be detected using the output line voltage instead of the output line current.

Furthermore, it is also possible to detect based on the phase difference between the output line current and the output line voltage.

[Effects of the Invention] The drive control device of the present invention can operate an air conditioning compressor motor with high efficiency <1) with a simple and inexpensive configuration, and can also suppress the generation of harmonics caused by the inverter. .

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, in which FIG. 1 is an overall block diagram of the device, FIG. 2 is a circuit diagram of the generator, FIG. 3 is a circuit diagram of the variable resistance section, and FIG. Figure 4 shows the variation of the rectifier output voltage with respect to the output line current, Figure 5 shows the frequency-voltage characteristics of the inverter output, Figures 6 and 7 show the conventional example, and Figure 6 shows the frequency-voltage characteristics of the inverter output. FIG. 7, which is an overall block diagram of the device, is a diagram showing the output waveform of the inverter. 1... Generator 11... Field coil 2... Voltage changing circuit 3... Rectifier 4... Inverter 5... AC motor 6... Air conditioning compressor 7... Current transformer (Load condition detection means) 8... Control circuit 9... Frequency setter Fig. 1 Fig. 3 Fig. 1s4 Fig. Output line current Fig. 5 Output same wave number (f')

Claims (1)

[Claims] a generator having a rotating field coil connected to a vehicle engine; voltage changing means for controlling excitation of the field coil to change the output voltage of the generator in accordance with an external signal; A rectifier that rectifies the DC voltage and outputs the DC voltage; an inverter that converts the DC voltage to an AC voltage of a predetermined frequency; an AC motor that is rotationally driven by the AC voltage of the inverter and operates an air conditioning compressor; A drive control device for a vehicle air conditioning compressor, comprising means for detecting a load state, and control means for applying the external signal to the voltage changing means in accordance with the detected load state.