JPS6364597A - Inverter air conditioner - Google Patents

Abstract

PURPOSE:To increase output torque according to the increment of load torque and recover from stalling quickly, by setting the output voltage and output frequency of an inverter with excess current signal. CONSTITUTION:From a micro-computer 38, the frequency of a frequency setting section 41 and the voltage of a voltage setting section 42 are fed to a PWM (pulse width modulation)generating section 40. The output of the PWM generating section 40 is fed to a base amplifier 36 via a buffer 37. By the base amplifier 36, a power transistor 35 is driven. In this case, when the load of a compressor 34 gets greater, then frequency is lowered by the excess current signal of an excess current detector 39 through the micro-computer 38, in order to protect the power transistor 35. As a result, generation torque is increased. Then, by lowering the frequency, a pattern refrigerant flow rate is reduced, and a compressor load is also reduced, and so. a device is quickly recovered from a stalling state.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an inverter air conditioner that lowers the frequency without lowering the voltage or increases the voltage without lowering the frequency when stalling.

[Conventional technology]

Figure 4 shows the V/F pattern of constant V/F control shown in ``rAC servo motor and microcontroller control'' (Songgo Denshi Publishing) 2.3.1 Principle of rv/F control''. Conventional single-inverter air conditioners were controlled using this pattern. FIG. 5 shows a block diagram of the configuration of an inverter in a conventional inverter air conditioner. In this Figure 5, 31
is a commercial power source, 32 is a diode bridge that converts alternating current to direct current, 33 is a smoothing capacitor, and 3ti is a compressor. This compressor 34 is driven by a power transistor 35 as a switching element of an inverter, and the power transistor 35 switches direct current. On the other hand, the overcurrent detector 33 detects the direct current flowing into the power transistor 35.
The two outputs are sent to a microcombinator 38 (hereinafter referred to as a microcomputer). The microcomputer 38 is configured to send the frequency from a frequency 8 setting section 41 and the voltage from a voltage setting section 42 to a PWM (pulse width modulation) generating section 40 . The output of the PWM generator 40 is sent to the base amplifier 36 via a buffer 37. This base amplifier 36 operates the power transistor 35. Next, the operation will be explained. The basic operation of the inverter is to convert the commercial power supply 31 to DC using a diode bridge 32.
The DC power is smoothed by the smoothing capacitor 33 and supplied to the power transistor 35. On the other hand, the PWM signal from the microcomputer 38 is sent to the power transistor 35 via the buffer 37 and the base amplifier 36, and the power transistor 35 switches the DC power supply according to the signal from the base amplifier 36 to generate pseudo AC. , drives the compressor 34. Here, when the load on the compressor 34 becomes large, the microcomputer 38 uses the overcurrent signal from the overcurrent detector 39 to control the frequency to be lowered to protect the power transistor 35 (
conventional stall control). This operation flow is shown in FIG. In this FIG. 7, in step S1, the overcurrent detector 39
When detecting an overcurrent, the frequency is lowered in step S2 as described above. At this time, in the conventional ■ (voltage)/F (frequency) constant control, the voltage automatically decreases, but as shown in Figure 6, even if the voltage decreases from A to B, the generated torque will change from A' to B. ', and the output torque remains unchanged.

[Problems to be solved by the invention]

Conventional inverter air conditioners perform constant torque stall control with a constant V/F as described above, so the output torque is not increased as required for the load torque, resulting in unnecessarily lowering the frequency. It had become. This invention was made to solve this problem, and it is possible to increase the output torque with respect to the increase in the load torque.
The purpose is to obtain an inverter air conditioner that quickly recovers from a stall.

[Means to solve the problem]

The inverter air conditioner according to the present invention is provided with an overcurrent detection means, an inverter output means setting means, and an output voltage setting means.

[For use]

In this invention, the output voltage and output frequency are set by the overcurrent signal detected by the overcurrent detection means, and when stalling, the frequency is lowered without lowering the voltage, or the voltage is increased without lowering the frequency.

【Example】

Embodiments of the inverter of the present invention will be described below with reference to the drawings. The configuration itself is the same as that shown in FIG. 5, and its explanation will be omitted, and will be explained using the operation pattern of the embodiment shown in FIG. 1 and the flowchart shown in FIG. 2. When an overcurrent signal is input at point A in FIG. 1 (step 201), it is determined whether the frequency is the minimum value (step 202), and if it is not the minimum value, the frequency is lowered (step 203). As a result, in Figure 1, the relationship between voltage and frequency is A.
As the point moves from point B to point B, the generated torque also moves from A' to B' and increases. Furthermore, by lowering the frequency, the pattern refrigerant flow rate is lowered and the compressor load is also reduced. Due to the above two points, the vehicle can quickly recover from a stalled state. FIG. 3 is an operation pattern diagram of the second embodiment of the present invention, and FIG. 4 is a flowchart. When an overcurrent signal is input at point A shown in FIG. 3 (step 301)
, determine whether the voltage is at the maximum value (step 302),
If it is not the minimum value, the output voltage is turned on (step 303). Moreover, if it is the maximum value, the frequency is lowered (step 304). As a result, in Figure 3, the relationship between voltage and frequency is A.
As the point moves from point B to point B, the generated torque also moves from A' to B' and increases. Therefore, compressor slippage is reduced and overcurrent does not flow. Furthermore, since the output frequency is not lowered, the performance of the air conditioner does not decrease even in a stalled state.

【Effect of the invention】

As explained above, this invention uses overcurrent input to perform control to lower the frequency without lowering the output voltage, or overcurrent detection to perform control to increase the output voltage without lowering the frequency. can recover from a stalled state.

[Brief explanation of drawings]

Fig. 1 is a pattern diagram according to an embodiment of the inverter air conditioner of the present invention, Fig. 2 is an operation flowchart of the same inverter air conditioner as above, and Fig. 3 is a pattern diagram according to a second embodiment of the inverter air conditioner of the present invention. A pattern diagram, FIG. 4 is an operation flowchart of the second embodiment of this in-hark air conditioner, FIG. 5 is a functional block diagram of the conventional and present inverter air conditioners, and FIG. 6 is a conventional inverter air conditioner. The pattern diagram in FIG. 7 shows the operation of a conventional inverter air conditioner. 31...Commercial power supply, 32...Diode bridge,
33... Smoothing capacitor, 34... Compressor, 35
...Power transistor, 36...Base amplifier,
37... Buffer, 38... Microcomputer, 39... Overcurrent detector, 40... PWM generation section, 41... Frequency setting section, 42... Voltage setting section. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Daikun Masu (2 idiots) Figure 1 Circular mantissa Figure 3 Figure 4 Figure 5, 32 Figure 6 Figure 7 σD

Claims (1)

[Claims] In an air conditioner having an inverter device that converts a commercial AC power source into DC and obtains pseudo AC by switching with a switching element such as a power transistor, means for detecting an overcurrent in the DC section, and independent control of the frequency and voltage of the pseudo AC. and a control means for performing stall control to lower the frequency without changing the voltage of the pseudo AC or to increase the voltage without changing the frequency of the pseudo AC in the case of the above-mentioned overcurrent. An inverter air conditioner characterized by: