JPH07298673A - Inverter control equipment - Google Patents

Abstract

PURPOSE:To prevent a drive circtuit from being damaged or burnt by allowing the circuit to operate for a specified time before it is stopped after the stop of a motor. CONSTITUTION:A motor 46 is started by forced commutation, and is kept operating after it has been stabilized. To stop the rotating motor 46, the frequency is reduced from the steady-state operating frequency to 0Hz by means of PAM 11. Immediately after the transition from the steady-state operating frequency to 0Hz, the voltage of a capacitor 27 does not change from 50V to 0V, and a voltage of approx. 10V remains. For the reason, a certain time must be allowed before stopping a drive circuit 13. To cope with this, when frequency becomes 0Hz, a timer is started so that, when a specified time has passed, all the transistors 31-33, 34-36 in the drive circumit 13 will be turned off. This prevents feedthrough current from being produced in the circuit after the motor 46 is stopped. That eliminates factors requiring increased cost, prevents damage to the circuit and significantly improves the reliability and safety of the circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control device.

[0002]

2. Description of the Related Art Conventionally, in a type such as a 50-liter refrigerator that does not require much horsepower, a PAM driving switching element for varying an output voltage from a power supply smoothing unit of an inverter controller is provided, The control of reducing the voltage and then inputting it to the drive circuit has been performed. ,
This is because an inexpensive drive circuit could be used by reducing the voltage, and it was being used from the viewpoint of cost reduction.

However, when the voltage control unit (PAM) is used in the inverter control device, when the motor is stopped,
If the frequency from the PAM transistor to the motor is gradually lowered and the drive circuit is stopped at the same time when the frequency becomes 0 Hz, the voltage remains in the capacitor in the PAM, and a through current occurs in the drive circuit. The circuit was damaged, and in the worst case, the circuit burned.

[0004]

As described above, the conventional inverter control device using the PAM has a drawback that a through current is generated when the motor is stopped, the circuit is damaged, and in the worst case, the circuit burns. Therefore, it is an object of the present invention to eliminate the above drawbacks and improve the reliability and safety of the circuit.

[0005]

In order to achieve the above object, the present invention provides a power supply input means for inputting an AC voltage, a power supply smoothing means for smoothing an AC current input from the power supply input means to a direct current, and Voltage varying means for varying the voltage smoothed by the power source smoothing means, motor rotation control means for controlling the current flowing through the motor composed of the stator and the mover after varying the voltage by the voltage varying means, and after stopping the voltage varying means. And a control unit for controlling the motor rotation control unit to be driven until a predetermined time elapses.

In order to achieve the above object, in the present invention, a power source input means for inputting an AC voltage, and a power source smoothing means for smoothing an AC current input from the power source input means to a direct current.
Voltage varying means for varying the voltage smoothed by the power source smoothing means, motor rotation control means for controlling the current flowing through the motor composed of the stator and the mover after varying the voltage by the voltage varying means, and stopping the voltage varying means. And a control means for controlling the motor rotation control means after a lapse of a predetermined time and stopping the motor rotation control means when the predetermined time is reached.

Further, the predetermined time is characterized in that the voltage of the voltage varying means is detected and set based on this voltage value. Further, it is provided with a voltage storage means for storing the voltage to be supplied to the control means even if the voltage input from the power supply input means is interrupted.

[0008]

In this structure, the drive circuit is stopped after a lapse of a predetermined time after the motor is stopped, thereby preventing damage to the circuit and burning of the circuit.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a refrigerator will be described in detail below with reference to FIGS. In this embodiment, a helical blade type compressor is used as the compressor of the refrigeration cycle.

First, the overall configuration will be described with reference to the circuit diagram of FIG. 1 and the block diagram of FIG. The power supply smoothing means 1 is composed of resistors 3, 5, a diode bridge 7 and a capacitor 9, which rectify and smooth a commercial AC power supply to obtain a DC power supply, and its positive (+) and negative The (−) terminal is connected to the input terminals 15 and 17 of the drive circuit 13 via a PAM (pulse amplitude modulation) 11, respectively.

The PAM 11 which is the voltage varying means 19 is a PA
Transistor 21 for M, flywheel diode 2
3, a reactor 25 and a capacitor (C1) 27, which vary the voltage value output by the power source smoothing means 1 described above.

The drive circuit 13 as the motor rotation control means 29
Are NPN type transistors 31 to 33 and 34 to 3 which are semiconductor switching elements between the input terminals 15 and 17.
6 are connected in a three-phase bridge. Freewheel diodes 37 to 42 are connected in parallel to the transistors 31 to 36, respectively. The common connection point of the transistors 31 and 34 is connected to the output terminal 43, the common connection point of the transistors 32 and 35 is connected to the output terminal 44, and the common connection point of the transistors 33 and 36 is connected to the output terminal 45.

The brushless DC motor 46 includes U, V and W
A stator 47 having phase stator windings 47U, 47V and 47W and a permanent magnet type rotor (not shown) are provided. One terminal of the stator windings 47U, 47V and 47W is commonly connected, and the other terminals are connected to the output terminals 43, 44 and 45 of the drive circuit 13, respectively.

The voltage dividing circuit 51, which is the position detecting means 49, is composed of voltage dividing resistors 53 to 58, and has a stator winding 47.
Each one terminal of U, 47V and 47W, that is, the drive circuit 13
Between the output terminals 15 and 17 and the ground (the input terminal that is the ground side terminal of the drive circuit), the series circuit of the voltage dividing resistors 53 and 56, the series circuit of the voltage dividing resistors 54 and 57, and the voltage dividing resistor. It is configured by connecting a series circuit of 55 and 58.
Then, the voltage dividing resistors 53 and 56, and the voltage dividing resistors 54 and 57.
And the common connection point of the voltage dividing resistors 55 and 58 to the detection terminal 5
They are 9, 60 and 61.

The control circuit 65, which is the control means 63, comprises a microcomputer 67, and its six output ports are connected to the transistors 31 to 33 and 34 to 36 of the drive circuit via the transistor driver 69. Further, the control circuit 65 is connected to the PAM 11.

Operation power source 73 as control circuit moving means 71
Is composed of a transformer 75, a diode bridge 77, a three-terminal regulator 79, a free wheel diode 83 which is a voltage storage means 81, and a capacitor (C2) 85. The input side is the power supply smoothing means 1 and the output side is a control circuit. Connected to 65.

Next, the operation of the embodiment of the present invention will be described. The AC power input from the power plug from the power outlet is the diode bridge 7 and the capacitor 9
Is smoothed by and converted to a DC power supply. At this time, DC
The output voltage will be about 1.4 times the AC input voltage. The output voltage of the smoothed DC power supply is controlled by the PAM 11 and applied to the drive circuit 13.

The drive circuit 13 is a 6-in-1 transistor array and is composed of upper stages 31 to 33 and lower stages 34 to 36, and a current flows through each coil of the motor 46 by a combination of these ON / OFF. This ON / OFF command is issued from the microcomputer 67 via the transistor driver 69.

Further, at the time of starting by turning on the power source, in order to rotate the permanent magnet which is the rotor of the brushless DC motor 46, an electric current is appropriately applied to each of the terminals 47U, 47V and 47W to generate an electrode of N or S pole. . As a result, the rotor repeatedly repulses and attracts, forcibly commutating,
Each of the terminals 47U, 47V and 47W senses the electrodes passed by the rotor and supplies a current so that the rotation can be continued. This is because after the power is turned on, a current is made to flow from the power supply smoothing means 1 to the operating power supply 73 and the control circuit 63 is supplied with a voltage of 5 V to start the microcomputer and turn on the drive circuit 13 via the transistor driver 69. This is done by giving a / OFF command.

During the rotation of the brushless DC motor 46, the terminal voltages UV and VV of the stator windings 47U, 47V and 47W.
And WV are divided by the voltage dividing circuit 51 to generate the detection voltage UV.
It is detected as a, VVa, and WVa, and these are input to the control circuit 65. The power supply voltage of the DC power supply means is divided by the reference voltage generation circuit 89 and output as the reference voltage VR, which is input to the control circuit.

When the rotation becomes stable, the induced voltage is detected and the next signal is generated. The above is a description of the normal operating state of the brushless DC motor, but in the following, the operation at startup when the power is turned on, particularly when the refrigerator is installed at home, will be described with reference to the flowchart in FIG.

When the installation of the refrigerator is completed and the power plug 87 is inserted and connected to a power outlet, when the electric components of the refrigerator are turned on, a voltage is applied by the operating power supply 73 and the control circuit 65 operates. Start (S
1).

After that, the motor 46 starts to rotate by the forced commutation, becomes stable, and continues to rotate (S
2). Then, when stopping the rotating motor 46,
The PAM 11 changes the steady operation frequency (for example, 60 Hz) to 0 Hz (S3, S4). At this time, as can be seen from FIG. 4 (proposal), the voltage of the capacitor (C1) 27 is reduced from 50 V to 0 immediately after the steady operation frequency becomes 0 Hz.
Since the voltage does not reach V and a voltage of about 10 V remains, it is necessary to wait for a fixed time before the drive circuit 13 is stopped. When the frequency reaches 0 Hz, the timer 91 starts counting (S5), and after a certain period of time (S6), the control circuit 6
5 to the transistors 31 to 33 and 3 of the driving circuit 13
All 4 to 36 are turned off (S7).

As a result, it is possible to prevent a through current from being generated in the circuit when the motor 46 is stopped, so that the reliability and safety of the circuit are significantly improved without increasing the cost.

As can be seen from FIGS. 5 and 6, the waiting time differs depending on the voltage value of the capacitor (C1) 27 when the steady operating frequency is set to 0 Hz to stop the motor 46. After the motor 46 is stopped, the voltage value of the capacitor (C1) 27, which is the voltage value detection means, is detected, and the stop of the drive circuit 13 is delayed at least by the time corresponding to this voltage value.

FIG. 7 is a timing chart diagram according to an embodiment of the present invention. Further, since the voltage value required to drive the motor 46 is assumed in advance, the voltage value at the time of stop is also assumed, and at the same time, the standby time is also assumed. Therefore, it is possible to store the standby time in the control circuit 65 and control the standby time by the microcomputer 67.

Next, another embodiment will be described. The power plug 87 may be pulled out for reasons such as changing the arrangement of the refrigerator. In this case also, the voltage remains in the capacitor (C1) 27, but since the capacitor (C2) 85 which is the voltage storage means 81 (shown in FIG. 2) is provided, the control circuit 6
The operation power supply 73 for driving the control circuit 6 is controlled by the control circuit 6 for a fixed time (about 10 seconds) even if the brushless DC motor drive device is stopped.
It is possible to store the voltage (about 5 V) required to drive the No. 5 circuit.

Thus, even if the circuit suddenly stops, the voltage for driving the drive circuit 65 is secured for a certain period of time, so that it is possible to wait until the voltage of the capacitor (C1) 27 becomes 0V. Through current (about 10 A) can be eliminated.

In the embodiment of the present invention, after the motor 46 is stopped,
Although the driving circuit 13 was stopped after delaying the waiting time, it is the same if the driving circuit 13 is not stopped. Further, although the 6-in-1 transistor array is used as the driving circuit 13, the present invention is not limited to this, and a 3-in-1 or 2-in-1 transistor array or individual transistors may be used.

[0030]

As described above, according to the present invention, the PA
Since the drive circuit is stopped after a lapse of a fixed time after M is stopped, it is possible to obtain the effect of improving the reliability and safety of the circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram according to an embodiment of the present invention.

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

FIG. 3 is a flowchart according to an embodiment of the present invention.

FIG. 4 is a diagram showing a voltage in a capacitor according to an embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a voltage value and a standby time according to an embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between an operating frequency and a standby time according to an embodiment of the present invention.

FIG. 7 is a timing chart according to an example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power source smoothing means, 11 ... PAM, 19 ... Voltage varying means, 27 ... Capacitor (C1), 29 ... Motor rotation control means, 46 ... Motor, 65 ... Control means, 69 ... Transistor driver, 71 ... Control circuit moving means , 81 ... Voltage storage means, 85 ... Capacitor (C2), 87 ... Power plug, 91 ... Timer.

Claims (4)

[Claims] 1. A power supply input means for inputting an AC voltage, a power supply smoothing means for smoothing an AC current input from the power supply input means to a direct current, and a voltage varying means for varying the voltage smoothed by the power supply smoothing means. After the voltage is varied by the voltage varying means, the motor rotation control means for controlling the current flowing through the motor composed of the stator and the mover, and for driving the motor rotation control means until a predetermined time elapses after the voltage varying means is stopped. An inverter control device comprising: a control unit for controlling. 2. A power supply input means for inputting an AC voltage, a power supply smoothing means for smoothing an AC current input from the power supply input means to a direct current, and a voltage varying means for varying the voltage smoothed by the power supply smoothing means. After the voltage is varied by the voltage varying means, the motor rotation control means for controlling the current flowing through the motor composed of the stator and the mover, and the motor rotation control means for a predetermined time after the voltage varying means is stopped are driven for the predetermined time. And a control means for controlling the motor rotation control means so as to stop. 3. The inverter control device according to claim 1, wherein the predetermined time is set based on a voltage value detected by the voltage varying means. 4. The inverter according to claim 1, further comprising a voltage storage unit that stores the voltage supplied to the control unit even if the voltage input from the power supply input unit is interrupted. Control device.