JPS59213285A - Protecting device of inverter circuit - Google Patents

Abstract

PURPOSE:To protect an inverter circuit by stopping an inverter circuit when an overcurrent is flowed to the inverter circuit, and further outputting a signal for stopping a load to a control signal generator to an inverter controller. CONSTITUTION:A control signal from a terminal IN is inputted to control, for example, the rotating speed of a compressor motor 1. A double voltage rectifier 3 converts an AC power source 2 to a DC and supplies it to an inverter circuit 4. The circuit 4 is composed of power transistors 5-10, converts a DC to an AC to drive the motor 1. A DC current detecting resistor 11 detects the current flowed to the circuit 4, and a current transformer CT detects the current flowed to the rectifier 3. A protecting circuit 4 interrupts a base drive circuit 13 for applying a switching signal to the transistors 5-10 of the circuit 4 when the current flowed to the resistor 11 or the transformer CT exceeds the prescribed value, and simultaneously sets a transistor 14 to ON state to shortcircuit a control signal applied to a terminal IN to an earth level. In this manner, it can be effectively protected.

Description

Detailed description of the invention (a) Industrial application field The invention relates to a protection mechanism that operates when an overcurrent flows through the inverter circuit. The inverter control circuit that outputs the switching signal is also configured to output a stop control signal.

(b) Prior art In general, an inverter circuit that converts surface light into alternating current is used and the frequency of the alternating current load connected to this inverter circuit is controlled. flows. In order to prevent damage to the transistors constituting the inverter circuit at the time of this overcurrent, a protection mechanism has been provided to cut off the flow of current to the impark circuit, or the operation of the inverter circuit has been stopped. (~
However, with this kind of protection mechanism, the protection mechanism is restored by cutting off the current to the inverter circuit, and if the overload condition is not resolved, overcurrent flows again and the protection mechanism is activated, causing a chattering phenomenon. Met. Furthermore, if a control signal generator is provided separately from the load, inverter circuit, inverter control circuit, etc., the user cannot easily recognize the overcurrent state of the inverter circuit. Therefore, a control signal is sent to the inverter control circuit.
If maintenance and inspection were delayed, the same chakuri knob phenomenon as above would occur.

(c) Purpose of the Invention In view of the above problems, the present invention provides that when a current flows through the inverter circuit for over 1 hour, when the operation of the inverter circuit is stopped, a control signal to the inverter control circuit is sent to the inverter control circuit at 1 o'clock in 1 row. - The inverter circuit is protected against overcurrent by switching to a signal that causes the inverter to stop.

2) Structure of the Invention The inverter circuit protection device according to the present invention comprises an inverter circuit that converts direct current into alternating current to drive a load, an inverter control circuit that supplies switching signals to this inverter circuit, and (Equipped with a control signal generator that outputs control credit to the 11 circuit, and a protection circuit that operates when an overcurrent flows through the inverter circuit, and at the same time, the operation of this protection circuit stops the operation of the inverter circuit.
1-7 protects the inverter circuit against overcurrent by stopping the load and outputting the /:,) signal from the control signal generator.

←) Example Hereinafter, the example of the present invention will be explained based on FIG. 1 and FIG. 1st part
The figure shows an electric circuit diagram of an inverter device used in the outdoor unit of an air conditioner. A control signal (voltage value change) from the OUT terminal in Fig. 2, which will be described later, is input from the IN terminal, and compression is performed based on this control signal. The cooling capacity is controlled by controlling the rotation speed of the machine motor (1). That is, (2) is an AC power supply, (3) is a voltage doubler rectifier circuit that converts AC to DC,
(4) is an impark circuit that converts direct current to alternating current,
This inverter circuit (4) is a power transistor (5)
00), and further includes a compressor motor (i) VC
It is connected. (11) is a resistor for DC current detection that detects the current flowing in the inverter circuit (4), (C, T)
is a voltage doubler rectifier circuit (3) from an AC power supply (2), a current transformer that detects the flowing AC current, and an inverter circuit (
4) protection circuit, and when the protection is activated, the DC current flowing through the DC current detection resistor αJ) or the current transformer (C
, T) exceeds a predetermined current value, the power transistor (
5) to (10) The base drive circuit θ3) that provides the K switching signal is cut off, and at the same time, the transistor (
14) is turned on, and the control signal applied to the IN terminal is short-circuited to Anis l/Bell.

The operation of this protection circuit (I2) has a differential with respect to the detected current value of the resistor (11) and current transformer (C, T), and prevents the chattering operation phenomenon of the protection circuit (1). .05) is R, OM (read only memory) which outputs the switching signal of the pace drive circuit 03) to the worker 1/ranosister (5) to θ0), and A, /1) converter 06, which will be described later. ), counter 07), and V/F converter (18) together constitute an inverter control circuit.

This f (, 405 to O) is divided into a plurality of single address sections by specifying the upper 4 bits of the address, and each section contains pWM (or 1) with varying amplitude.
Power transistors (5) to (1) using the 8M) method
The number of turns for one period of the switching signal of 0) is shown in 1.
, has been ho. Therefore, this ROM (one address section (address of upper 4 bits) f, c A, /J
)? Specified by binary digital signal output from converter 06)
-1 1 degree, the address (lower 9 bits) of this R2M17) is output as a binary digital signal from the counter 07), and the switching signal is read out from the ROM (15) with the finger 1jj::l- (-7). Power transistors (5) to 0
By driving the A/D converter (1G), the frequency and amplitude output from the counter (In) can be obtained by driving the counter 0).Furthermore, the counter 07) is driven by the input from the V/F converter. Based on the pulse signal whose period changes, the count value increases sequentially from O and outputs a digital signal, and when the pattern for one period of the switching signal is read from R, OM (Iω), the digital signal output is counted again from O. θ9 is a driver circuit, and IN
It outputs the voltage according to the control signal (voltage value change) given to the terminal to the A/D converter α6) and the V/F converter 08).

Figure 2 shows an electric circuit diagram of the indoor unit of the air conditioner, which corresponds to the control signal generator. (28), resistance (28), digital display for room temperature and timer time (display section for displaying 2 units, operation mode, etc.), resistance (2!i), negative characteristic thermistor C30
), Comparison 14H (311 room temperature detection circuit (3L microprocessor current (2 [)) and digital output as described above @ (@'I converting to pressure pressure change)/A converter mark), etc. It has many surrounding areas. The output of this D/A converter (G) is activated only when the output voltage ratio changes from the voltage of O to the voltage of O or higher (it does not operate if the voltage changes in other cases).
It is output from the OUT terminal to the IN terminal of the outdoor unit via the delay circuit 04) which delays the output for about 3 minutes and the driver G■. Further, this driver 09 has a limit mechanism that controls the output current when the load is short-circuited (when the transistor O (a) of the outdoor unit is in the ON state). Furthermore, the resistance 09) of the room temperature detection circuit T3 and the negative characteristic thermistor C'IO
) is supplied with voltage from the comparator (36),
The inverting input terminal of this comparator (support) is connected to the connection point with resistor 07), (support), and the non-inverting input terminal is resistor 09)
, (connection point of 4f++ and resistor (4I), capacitor (
42) and the connection point of diode 03).

In addition, the capacitor (one end of the 4-powder is connected to the output terminal of the driver (c). Also, the resistor 07), □□□), 0
9), (40), (40) The constants of the capacitor (42) are set so that the output from the driver (comparator (support)) switches to a low voltage when the output voltage from the burner becomes less than a predetermined value. ing.

Since the embodiment of the present invention is configured as described above, when the operating state of the indoor unit, for example, the indoor temperature setting value, is set using the operating state setting device (21) and operation is started, the microprocessor ) is the resistance (24) of the room temperature detection circuit G,
The room temperature obtained by the negative characteristic thermistor @) is sequentially input to (c), (a)), and (5) for comparison. At the same time, this room temperature is displayed on the digital display (c) of the display section (23).

Further, depending on the difference between the set temperature and the room temperature, the microprocessor (20) outputs a large digital output when the difference is large, and a small digital output when the difference is small, to the D/A converter (c). The output of this D/A converter t33) changes from the OFF signal (OCVI voltage) of the compressor motor (1) to the ON signal (
This ON signal is supplied to the driver (035) through a delay circuit (b) that delays the ON signal for approximately 3 minutes only when the voltage is switched to a voltage higher than (OcV). This is supplied as a control signal to the IN terminal in Figure 1).

Next, when the control signal given to this INi child changes, V'
/F converter O& pulse signal period changes, counter 07'l counts this pulse signal, ROM05)
Digital data of the lower 9 bits of the hair address (H issue and (
-7 output. Also, based on this control signal, A, /
L) Converter 06) outputs a digital data signal (-7 This digital data is the 2nd position 4 of the address of ROMQ5)
Specify the address range using bits. Therefore, by sequentially scanning the pulse signal of the V/F converter 08), the filter 7 (17) reads out the pattern of the switching signal for one cycle within the address section. When this one cycle worth of switching signals is read out, the counter (
j7) counts from O and again reads out the switching signals for one round 4υ], so the switching signals are continuously supplied to the power transistors (5) to 00) via the pace drive circuit (13). be.

This drives the compressor motor (1) to perform cooling operation.

In this way, based on the control signal from the indoor unit, ROM05
The switching signal pattern from 1 to /' and -e is changed to change the rotational speed of the compressor motor () to change the cooling capacity of the air conditioner.

During such operation, if an overcurrent flows to the inverter circuit (4) due to compressor motor (INVC burnout or lock condition), the protection circuit θ2) ), the output of this protection circuit 02) is given to the reset terminal (I()) of the base drive circuit (I3), and a switching signal is sent from the ROM (15) to the power transistors (5) to 00). At the same time, the transistor 04) is turned on to substantially short-circuit the IN terminal. If the 51CIN terminal, that is, the OUT terminal of the indoor unit, becomes short-circuited, the screwdriver 〇! 5) The load is resistance (
In order to maintain a predetermined control signal (voltage) with a small load such as 4" or (44), an excessive current output is required, but this driver 05) has a current output as described above. Since the output current is limited to a predetermined value, the output voltage drops to approximately OCV.When (transistor 04) is in the ON state, the current limit value ) is set so that the output voltage drops to approximately 0 [■].) When the output voltage of this driver reaches approximately 01lV'I, after a predetermined time determined by the discharge of the charge in the capacitor (42), The voltage applied to the non-inverting input terminal of the comparator (13G) becomes lower than the reference voltage determined by the resistors 07) and (2)), and the output of the comparator α;) changes to a low voltage.
When the output of (support)) changes to a low voltage, the resistance c! 9) and the negative characteristic thermistor 00) becomes a low voltage, and the resistance value of the negative characteristic thermistor @) increases (the sensing temperature of the negative characteristic thermistor (30) becomes lower). The same is true. Therefore, the microprocessor (20) receives input from the room temperature detection circuit (2) indicating that the room is sufficiently cold in the air conditioner (111), and sends the compressor motor (20) to the outdoor unit via the OUT terminal.
) is used to output a stop signal (OCV") voltage control signal. At this time, the room temperature is displayed at the lowest temperature on the digital display. At the same time, the indoor unit is switched to ventilation operation. .After this, inverter circuit (4)
The current flowing to the protection circuit θ decreases, the output from the protection circuit θ is cut off, the pace drive circuit (13) is connected, and the transistor (14) becomes in the 7J' OF, F state.
A drive signal for the compressor upper (1) is output from the microprocessor (20) of the indoor unit. In this way, no matter what state is returned to, the operation of the delay circuit t34) will prevent the cotton machine motor (1) from driving for about 3 minutes. Therefore, the protection circuit (12) will be activated once. Then, the drive of the compressor motor (1) is inhibited at least for a predetermined period of time due to the activation of the delay circuit (2).During this period, the display mechanism of the indoor unit indicates the lowest temperature, making it easy for the user to It is possible to recognize abnormal conditions and perform necessary maintenance and inspection.

In the above example, an air conditioner exclusively for cooling was used, but the use is not limited to this; it can also be used for heating and dehumidification.
・It's okay. The embodiments of the impark circuit protection device according to the present invention are not limited to the above-mentioned air conditioners.

(F) Effects of the Invention The inverter circuit protection device of the present invention uses a control signal generator to stop the operation of the ink circuit and at the same time stop the ink circuit when an overcurrent flows through the inverter circuit. Therefore, if an overcurrent flows through the inverter circuit (well, the control signal from the control signal generator is given to the inverter control circuit as a stop 1- signal, and thereby the inverter circuit is output from When the output of the switching signal is stopped and the operation of the ink cartridge I path is stopped 1-1 by cutting off the switching signal path, the ink path can be reliably stopped overnight.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of an outdoor unit when the present invention is applied to an air conditioner, and FIG. 2 is an electric circuit diagram of an indoor unit connected to the IN terminal of FIG. 1.

Claims (1)

[Claims] (1) An inverter circuit that converts direct current to alternating current to drive a load, an inverter control circuit that supplies a switching signal to this inverter circuit, and a control signal generator that outputs a control signal to this inverter control circuit. , when an overcurrent flows through the inverter circuit, the inverter circuit is stopped and the load is further stopped 7,)44. A protection circuit for an inverter circuit, characterized in that a protection circuit for outputting a signal to a control signal generator (+t!ik) is provided.