KR101948976B1 - Inverter control circuit - Google Patents

Abstract

In the inverter control circuit, the electric charge accumulated in the condenser can be appropriately discharged, and the abnormal voltage detection means and the inverter stop / return means can be configured inexpensively.
When the DC voltage VC output from the capacitor 6 exceeds the predetermined normal range (below the breakdown voltage VB of the Zener diode 12), the detection signal VA corresponding to the DC voltage VC is outputted Wherein the impedance is higher than that when the DC voltage (VC) exceeds the normal range when the DC voltage (VC) is included in the normal range while discharging the capacitor (6) (20) for converting the DC voltage (VC) into an AC voltage (MU, MV, MW) and supplying it to the load (30) in accordance with the detection signal A return control circuit 40 is provided.

Description

[0001] INVERTER CONTROL CIRCUIT [0002]

The present invention relates to an inverter control circuit.

As a background of this technical field, in the summary of the following Patent Document 1, it is described that, in the circuit of the air conditioner provided with the DC voltage detecting means 22 of the inverter section 19, 6, a pair of phase-voltage detecting means 7, a voltage phase calculating means 9 by means of the input, a transistor module 4 in which a plurality of transistors and diodes are incorporated, A DC voltage detection means 12 and an abnormal voltage monitoring means 13 connected to the DC voltage detection means 12; a transistor control means 11; A harmonic current suppressing device 17 composed of a reactor 3 and a smoothing capacitor 16 connected to the DC voltage part are arranged in the control circuit 10 for determining the control method of the module 4 .

Japanese Patent Application Laid-Open No. 10-14253

Patent Document 1 does not specifically describe the operation when the abnormal voltage monitoring means 13 detects an abnormal voltage. Normally, in order to prevent the inverter unit 19 from being damaged, the inverter unit 19) is stopped. However, when the inverter unit 19 is simply stopped, the abnormal voltage is maintained until the electric charge accumulated in the smoothing capacitor 16 is spontaneously discharged, so that the operation of the inverter unit 19 can not be resumed do. Therefore, it is conceivable to provide a discharge circuit for discharging the charge accumulated in the smoothing capacitor 16 when an abnormal voltage is detected. However, installing a discharge circuit separately leads to an increase in cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inverter control circuit capable of appropriately discharging a charge accumulated in a capacitor and capable of constituting an abnormal voltage detection means and an inverter stop / .

According to an aspect of the present invention, there is provided an inverter control circuit comprising:

When the direct current voltage output from the capacitor exceeds a predetermined normal range, discharging the capacitor while outputting a detection signal corresponding to the direct current voltage, and when the direct current voltage is included in the normal range, An abnormal voltage detection and discharge circuit which has an impedance higher than that when it exceeds the normal range,

And a stop / return control circuit for converting the direct-current voltage into an alternating-current voltage in accordance with the detection signal to put the inverter for supplying the load into a stopped state.

According to the inverter control circuit of the present invention, the electric charge accumulated in the condenser can be appropriately discharged, and the abnormal voltage detection means and the inverter stop / return means can be constructed at low cost.

1 is a block diagram of a motor drive apparatus according to a first embodiment of the present invention;
Fig. 2 (a) is a waveform diagram of the alternating-current voltage VS in the motor driving apparatus of the first embodiment, Fig. 2 (b) is a waveform diagram of the same dc voltage VC, ) Is a waveform diagram of the control command voltage VSP.
3 is a diagram showing the relationship between the DC voltage VC and the control command voltage VSP;
4 is a block diagram of a motor drive apparatus according to a second embodiment of the present invention;
5 is a block diagram of a motor drive apparatus according to a third embodiment of the present invention;
6 is a block diagram of a motor drive apparatus according to a fourth embodiment of the present invention;
7 is a block diagram of a motor driving apparatus according to a fifth embodiment of the present invention;
8 is a block diagram of a motor drive apparatus according to a sixth embodiment of the present invention.
9 is a block diagram of a motor drive apparatus according to a modification of the first embodiment;

[First Embodiment]

≪ Configuration of Embodiment >

(Total configuration)

First, the configuration of the motor drive apparatus according to the first embodiment of the present invention will be described with reference to a block diagram shown in Fig.

1, the converter 4 converts the AC voltage VS supplied from the commercial power supply 2 into a DC voltage VC. The converter 4 can be constituted by, for example, a full-wave rectification circuit in which four diodes are bridge-connected when the commercial power supply 2 is single-phase. The capacitor 6 is connected between the voltage output terminal of the converter 4 and the ground potential (hereinafter referred to as " GND potential "), and charges are accumulated by the DC voltage VC. The configuration of the converter 4 is not limited to that described above, but it is preferable that the configuration is such that current does not flow back from the condenser 6 to the converter 4. [ When the converter 4 is constituted by the full-wave rectification circuit, in the normal state, the DC voltage VC becomes substantially equal to the peak value of the AC voltage VS. For example, when the alternating-current voltage VS is 220 [V] (the effective value), the direct-current voltage VC is about 2 x 220 V? 311 [V].

The abnormal voltage detection and discharge circuit 10 is connected in parallel to the condenser 6 and has a function of detecting abnormality of the direct current voltage VC and discharging the electric charge accumulated in the condenser 6. [ The stop / return control circuit 40 has a function of stopping the operation of the inverter 20 when the abnormal voltage detection and discharge circuit 10 detects an abnormality of the DC voltage VC. When the operation is not stopped by the stop / return control circuit 40, the inverter 20 converts the DC voltage VC into three-phase AC voltages MU, MV and MW and supplies the three-phase AC voltages MU, MV and MW to the motor 30, 30). The abnormal voltage detection and discharge circuit 10 and the stop / return control circuit 40 are collectively referred to as an " inverter control circuit ". Further, in the present embodiment, the motor 30 is assumed to be a three-phase synchronous motor that drives the indoor unit of the air conditioner or the fan of the outdoor unit. However, the type and application of the motor 30 are not limited thereto.

(Abnormal voltage detection and discharge circuit 10)

The abnormal voltage detection and discharge circuit 10 is constituted by connecting a zener diode 12 and resistors 14 and 16 in series and connecting the resistor 16 to the GND potential. The breakdown voltage VB of the Zener diode 12 is set to be a voltage slightly higher than the voltage fluctuation range on the specification of the DC voltage VC. For example, if the nominal voltage of the AC voltage VS is 220 [V] and the normal range (that is, the voltage fluctuation range in the standard) is ± 20%, the maximum voltage in the specification of the AC voltage VS is 264 [V] do. At this time, since the direct current voltage VC is about 2 × 264 [V] ≈373 [V], the zener diode 12 may be selected to have a breakdown voltage VB of about 440 [V] in consideration of the deviation.

The DC voltage VC is also within the normal range (below the breakdown voltage VB) so that the Zener diode 12 hardly flows current and the abnormal voltage detection and discharge circuit 10 is connected to the capacitor 6 The high impedance state is obtained. Thus, the detection signal voltage VA, which is the voltage of the connection point A of the resistors 14 and 16, becomes almost 0 [V]. On the other hand, when the alternating-current voltage VS rises beyond the normal range and thereby the direct-current voltage VC exceeds the breakdown voltage VB, a current flows in the abnormal voltage detection and discharge circuit 10. Since this current is proportional to " VC-VB ", the higher the DC voltage VC becomes, the larger the detection signal voltage VA becomes.

(Inverter 20)

As described above, the inverter 20 converts the direct-current voltage VC into three-phase alternating-current voltages MU, MV, and MW. This is realized by PWM-modulating the direct-current voltage VC by a plurality of switching elements (not shown). Therefore, the current supplied from the converter 4 to the inverter 20 is returned to the inverter 20 after flowing through the motor 30, and flows to the GND potential via the GH terminal. In addition, there may be a case where a resistor for overcurrent protection is mounted between the GH terminal and the GND potential. In addition, the control power supply voltage VCC of about 15 [V] is input to the inverter 20 for on / off control of the switching element.

A control command voltage VSP is input to the VSP terminal of the inverter 20. [ The control command voltage VSP is, for example, about 0 to 6 [V], and the inverter 20 controls the three-phase AC voltages MU, MV and MW in accordance with the voltage level. For example, the higher the voltage level, the higher the frequency of the three-phase AC voltages MU, MV and MW, and the lower the voltage level, the lower the frequency of the three-phase AC voltages MU, MV and MW. However, when the control command voltage VSP becomes less than a predetermined off voltage Voff (for example, about 1.8 [V]), the inverter 20 is brought into a stop state to stop the output of the three-phase AC voltages MU, MV and MW do. The control command voltage VSP may be a command voltage for controlling the three-phase AC voltage output of the inverter 20 such as a speed command, a Duty command, and a torque command.

(Stop / return control circuit 40)

In the stop / return control circuit 40, the detection signal voltage VA is input to the base terminal of the transistor 42, and the emitter terminal is connected to the GND potential. When the detection signal voltage VA becomes equal to or higher than the base-emitter saturation voltage of the transistor 42, the transistor 42 is turned on. Further, the stop / return control circuit 40 is supplied with the original control command voltage VSP0 from a not-shown master device. The resistor 46 and the capacitor 48 constitute a low-pass filter to remove high-frequency components included in the original control command voltage VSP0. This is to make the change in the control command voltage VSP gentler even when the original control command voltage VSP0 is abruptly changed. A resistor 44 is connected between the resistor 46 and the collector terminal of the transistor 42 to limit the current to the transistor 42. [ The resistor 44 may or may not be provided.

When the transistor 42 is in the OFF state, the current Itr flowing through the resistor 44 becomes almost 0 [A], so that the original control command voltage VSP0 from which the high frequency component has been removed is supplied to the inverter 20 as the control command voltage VSP. On the other hand, when the transistor 42 is turned on and the current Itr flows through the transistor 42, the original control command voltage VSP0 obtained by removing the high-frequency component is divided by the resistor 46, the resistor 44, And a voltage is supplied to the inverter 20 as the control command voltage VSP.

≪ Operation of Embodiment >

Next, an operation example according to the present embodiment will be described. 2 (a) to 2 (d) show examples of waveforms and the like of each part before and after an abnormal voltage is generated. FIG. 2 (a) shows the waveform of the amplitude value of the AC voltage VS, 2B is a waveform diagram of the DC voltage VC, FIG. 2C is a diagram of the transistor 42, and FIG. 2D is a waveform diagram of the control command voltage VSP. The value of the AC voltage VS before the time t1 is VS1, and it is increased to VS2 in the step shape at the time t1, the period from the time t1 to t6 is maintained at the VS2, and again at the time t6, . In the illustrated example, it is assumed that VS1 is a voltage within a voltage fluctuation range of the standard, and VS2 is a voltage about twice that.

Before time t1, the DC voltage VC is a value (VC1) which is substantially equal to the peak value (? 2 x VS1) of the AC voltage VS1 when the converter 4 is a full wave rectification circuit. Then, when the voltage VS1 rises in step form at time t1, the DC voltage VC gradually increases after time t1. At time t2, the DC voltage VC reaches VC2. The voltage VC2 is a value equivalent to the breakdown voltage VB of the zener diode 12. Therefore, at time t2, current starts to flow in the Zener diode 12 and the resistors 14 and 16. Before the time t2, the detection signal voltage VA is almost 0 [V], but after the time t2, the detection signal voltage VA rises in proportion to " VC-VB ".

Thereafter, at time t3, the DC voltage VC reaches VC3. This voltage VC3 is a voltage at which the detection signal voltage VA of the connection point A reaches the base-emitter saturation voltage of the transistor 42. [ Therefore, as shown in Fig. 2 (c), the transistor 42 is turned on at time t3. Thereafter, at time t4, the DC voltage VC reaches VC4. This voltage VC4 is a voltage at which the control command voltage VSP becomes the off voltage Voff. As a result, the inverter 20 is brought into a stop state, and the output of the three-phase AC voltages MU, MV, and MW is stopped. Thereafter, at time t5, the DC voltage VC becomes VC5. The voltage VC5 is substantially equal to the peak value of the voltage VS2, which is the AC voltage VS at that time, when the converter 4 is a full wave rectification circuit.

Here, the relationship between the DC voltage VC and the control command voltage VSP will be described with reference to FIG. In the illustrated example, it is assumed that the original control command voltage VSP0 supplied from a not-shown host apparatus is a constant value (6 [V]). When the direct current voltage VC is lower than the voltage VC3, the current Itr (see FIG. 1) flowing through the transistor 42 becomes almost 0 [A], so that the control command voltage VSP becomes substantially equal to the original control command voltage VSP0. However, when the direct current voltage VC becomes equal to or higher than the voltage VC3, the current Itr becomes proportional to " VC-VB ", so that the control command voltage VSP becomes lower than the original control command voltage VSP0 by the voltage drop amount generated in the resistor 46. [

However, when the DC voltage VC is near the voltage VC3, since the ON resistance of the transistor 42 is large, the current Itr is relatively small and the control command voltage VSP is close to the original control command voltage VSP0. When the DC voltage VC becomes near the middle value of the voltages VC3 and VC4, the ON resistance of the transistor 42 becomes small, and a comparatively large current Itr flows, and the slope of the control command voltage VSP to the DC voltage VC becomes large. As described above, when the direct-current voltage VC becomes VC4 or more, the control command voltage VSP becomes equal to or lower than the off voltage Voff, so that the inverter 20 stops outputting the three-phase AC voltages MU, MV and MW.

Returning to Fig. 2, when the AC voltage VS returns to VS1 at time t6, the charge of the capacitor 6 starts to be discharged through the abnormal voltage detection / discharge circuit 10 (see Fig. 1). At time t7, when the control command voltage VSP exceeds the off-voltage Voff, the inverter 20 enters the operating state. That is, the output of the three-phase AC voltages MU, MV, and MW is resumed in association with the control command voltage VSP. For example, at the frequency corresponding to the control command voltage VSP, the output of the three-phase AC voltages MU, MV, and MW is resumed. At the subsequent time t8, when the DC voltage VC becomes less than VC3, the transistor 42 is turned off, and the control command voltage VSP becomes equal to the original control command voltage VSP0. Thereby, the operation of the motor driving apparatus is returned to the normal state, and the motor 30 is rotationally driven at the speed corresponding to the original control command voltage VSP0.

When the DC voltage VC becomes lower than VC2 (the breakdown voltage VB of the Zener diode 12) at the subsequent time t9, the current hardly flows through the abnormal voltage detection and discharge circuit 10. Therefore, after time t9, the DC voltage VC gradually approaches VC1 due to the natural discharge of each part in the motor drive apparatus and the power consumption accompanying the motor drive. Here, the voltage VC4 is made higher than the voltage VC2 (breakdown voltage VB), which is one of the characteristics of the present embodiment. With this feature, the time of the overvoltage state is shortened by accelerating the discharge of the voltage equal to or higher than VC4, and even after the control command voltage VSP becomes the predetermined off voltage Voff or more, the abnormal voltage detection and discharge circuit 10 continues to discharge .

As described above, according to the present embodiment, when the AC voltage VS rises above the normal range and the DC voltage VC output from the capacitor 6 rises beyond the normal range, the abnormal voltage detection / It outputs the detection signal voltage VA in accordance with the direct current voltage VC, so that the transistor 42 can be turned on by the detection signal voltage VA and the inverter 20 can be stopped. When the AC voltage VS returns to the normal range, the abnormal voltage detection and discharge circuit 10 rapidly discharges the electric charge stored in the capacitor 6, so that the DC voltage VC can be returned quickly to the normal range.

Further, when the direct current voltage VC is within the normal range, almost no current flows in the abnormal voltage detection and discharge circuit 10, so that the power consumption in the abnormal voltage detection and discharge circuit 10 can be suppressed. Since the abnormal voltage detection and discharge circuit 10 also functions as " abnormal voltage detection " and " discharge ", as compared with the case where circuits for performing the respective functions are separately provided, Can be reduced.

[Second Embodiment]

Next, the configuration of the motor driving apparatus according to the second embodiment of the present invention will be described with reference to a block diagram shown in Fig.

In this embodiment, the inverter 130 shown in Fig. 4 is applied instead of the inverter 20 of the first embodiment. To the inverter 130, a control signal SD which is a binary signal is input. When the control signal SD becomes the H level (voltage equal to or higher than the predetermined threshold value), the inverter 130 enters the operating state and outputs the three-phase AC voltages MU, MV and MW to the motor 30. On the other hand, when the control signal SD is at the L level (voltage lower than the threshold value), the inverter 130 enters a stop state and stops outputting the three-phase AC voltages MU, MV and MW. The inverter 130 of the present embodiment also sets the three-phase AC voltages MU, MV and MW in accordance with the control command voltage VSP as in the inverter 20 of the first embodiment. However, in the present embodiment, since the control command voltage VSP is not operated on the basis of the DC voltage VC, the illustration of the relevant circuit is omitted.

In this embodiment, the stop / return control circuit 50 shown in Fig. 4 is applied instead of the stop / return control circuit 40 of the first embodiment. In the stop / return control circuit 50, the detection signal voltage VA is input to the base terminal of the transistor 52, and the emitter terminal is connected to the GND potential. One end of the resistor 51 is connected to the collector terminal and the control power supply voltage VCC is applied to the other end of the resistor 51. [ The voltage of the collector terminal of the transistor 52 is supplied to the inverter 130 as the control signal SD. The configuration of the present embodiment other than the above is the same as that of the first embodiment (Fig. 1).

In the above configuration, when the DC voltage VC is within the normal range, almost no current flows in the abnormal voltage detection / discharge circuit 10, so that the detection signal voltage VA becomes almost 0 [V]. Therefore, the transistor 52 is turned off, and the control signal SD is pulled up by the resistor 51 and becomes H level. As a result, the inverter 130 is in the operating state, and outputs the three-phase AC voltages MU, MV, and MW to the motor 30. [

On the other hand, when the DC voltage VC becomes higher than the breakdown voltage VB of the Zener diode 12, the current flowing in the abnormal voltage detection / discharge circuit 10 is proportional to " VC-VB ". When the DC voltage VC becomes higher and the detection signal voltage VA becomes equal to or higher than the base-emitter saturation voltage of the transistor 52, the transistor 52 is turned on. As a result, the control signal SD becomes a value close to 0 [V], that is, L level, so that the inverter 130 is brought into a stop state to stop the output of the three-phase AC voltages MU, MV and MW.

As described above, according to the present embodiment, the operation / stop state of the inverter 130 can be switched on the basis of the DC voltage VC similarly to the first embodiment, and an effect similar to that of the first embodiment is exhibited .

[Third embodiment]

Next, the configuration of the motor driving apparatus according to the third embodiment of the present invention will be described with reference to a block diagram shown in Fig.

In place of the control signal SD in the second embodiment, the negative logic control signal NSD is input to the inverter 140 of the present embodiment. In other words, when the control signal NSD is at the L level (less than the predetermined threshold voltage), the inverter 140 enters the operating state and outputs the three-phase AC voltages MU, MV and MW to the motor 30. On the other hand, when the control signal NSD reaches the H level (voltage equal to or higher than the threshold value), the inverter 140 enters a stop state and stops outputting the three-phase AC voltages MU, MV and MW. In this embodiment, the stop / return control circuit 60 shown in Fig. 5 is applied in place of the stop / return control circuit 50 of the second embodiment. The stop / return control circuit 60 is constituted by one electric wire 61 that supplies the detection signal voltage VA outputted from the abnormal voltage detection and discharge circuit 10 to the inverter 140 as the control signal NSD . The configuration of the present embodiment other than the above is the same as that of the second embodiment (Fig. 4).

In the above configuration, when the DC voltage VC is within the normal range, almost no current flows in the abnormal voltage detection / discharge circuit 10, so that the detection signal voltage VA becomes almost 0 [V]. Therefore, the control signal NSD goes to the L level, so that the inverter 140 enters the operating state and outputs the three-phase AC voltages MU, MV, and MW to the motor 30. [ On the other hand, when the DC voltage VC becomes higher than the breakdown voltage VB of the Zener diode 12, the current flowing in the abnormal voltage detection / discharge circuit 10 is proportional to " VC-VB ". When the DC voltage VC becomes higher and the detection signal voltage VA becomes equal to or higher than the threshold value, the control signal NSD becomes H level, so that the inverter 140 is put into a stop state to stop the output of the three-phase AC voltages MU, MV and MW.

As described above, according to the present embodiment, it is possible to switch the operation state / stop state of the inverter 140 based on the direct-current voltage VC in the same manner as in the first and second embodiments, The same effect can be obtained. The stop / return control circuit 60 of the present embodiment is simpler in configuration than the stop / return control circuits 40 and 50 of the first and second embodiments and can reduce the cost .

[Fourth Embodiment]

Next, the configuration of the motor driving apparatus according to the fourth embodiment of the present invention will be described with reference to a block diagram shown in Fig.

In this embodiment, an inverter 150 having an RS terminal is applied instead of the inverter 20 (Fig. 1) of the first embodiment. The function of the RS terminal will be described later.

In the abnormal voltage detection and discharge circuit 110 of the present embodiment, the zener diode 12 and the three resistors 14, 16, and 18 are sequentially connected in series and then connected to the GND potential have. The resistor 18 is a low-resistance shunt resistor. The connection point D of the resistors 16 and 18 is connected to the GH terminal of the inverter 150 through the electric wire 74. [ The detection signal voltage VA of the connection point A of the resistors 14 and 16 is connected to the RS terminal of the inverter 150 via the electric wire 72. [ These electric wires 72 and 74 are included in the stop / return control circuit 70 in the present embodiment.

Here, the function of the GH terminal of the inverter 150 is the same as that of the first embodiment (Fig. 1), and is a terminal for causing a current flowing through the motor 30 to flow to the GND potential. When the resistor 18 is connected between the GH terminal and the GND potential as in the present embodiment, the voltage VD at the GH terminal rises in proportion to the current flowing through the resistor 18. Therefore, when the voltage VD is measured, It is possible to detect whether or not an overcurrent flows in the inverter 150. [ Therefore, the voltage VD is referred to as " voltage corresponding to consumption current ".

The RS terminal is connected to the GH terminal and is used for detecting whether or not an overcurrent flows in the inverter 150 based on whether or not the consumption current corresponding voltage VD exceeds the predetermined threshold value VDth in the normal use method do. However, in the present embodiment, as shown in Fig. 6, the RS terminal is connected to the connection point A. Therefore, this significance will be explained. When the DC voltage VC is less than the breakdown voltage VB of the Zener diode 12, almost no current flows through the resistors 14 and 16, so that the detection signal voltage VA becomes equal to the consumption current corresponding voltage VD.

Therefore, inverter 150 can detect whether or not an overcurrent is generated in inverter 150, based on the comparison result of detection signal voltage VA and threshold value VDth, as in the case of the normal use method. On the other hand, when the DC voltage VC is higher than the breakdown voltage VB of the Zener diode 12, a current proportional to " VC-VB " flows through the resistor 16, The detection signal voltage VA becomes higher than the consumed current corresponding voltage VD. The configuration of the present embodiment other than the above is the same as that of the first embodiment (Fig. 1).

In the above configuration, when the DC voltage VC is within the normal range, the detection signal voltage VA is almost equal to the consumed current corresponding voltage VD. Therefore, unless an overcurrent flows in the inverter 150, the inverter 150 is in an operating state and outputs the three-phase AC voltages MU, MV, and MW to the motor 30. [ On the other hand, when the DC voltage VC becomes equal to or higher than the breakdown voltage VB of the Zener diode 12, a current flows to the abnormal voltage detection and discharge circuit 110, and the detection signal voltage VA becomes higher than the consumed current corresponding voltage VD. When the DC voltage VC becomes higher and the detection signal voltage VA exceeds the threshold value VDth, the inverter 150 enters a stop state to stop the output of the three-phase AC voltages MU, MV, and MW.

As described above, according to the present embodiment, the operation / stop state of the inverter 150 can be switched based on the DC voltage VC similarly to the first to third embodiments, The same effect can be obtained. In the present embodiment, since the operation state / stop state of the inverter 150 is switched using the RS terminal for detecting the overcurrent, the " overcurrent in the inverter 150 " and the " Can be detected through the common terminal (RS terminal), so that the circuit configuration can be simplified and the cost can be reduced as compared with the case where both are detected.

[Fifth Embodiment]

Next, the configuration of the motor driving apparatus according to the fifth embodiment of the present invention will be described with reference to a block diagram shown in Fig.

In this embodiment, the stop / return control circuit 80 shown in Fig. 7 is applied instead of the stop / return control circuit 40 (see Fig. 1) of the first embodiment. In the stop / return control circuit 80, the detection signal voltage VA is input to the base terminal of the transistor 84, and the emitter terminal is connected to the GND potential. One end of the relay coil 82b of the relay 82 is connected to the collector terminal, and the control power supply voltage VCC is applied to the other end of the relay coil 82b. The control power supply voltage VCC is supplied to the VCC terminal of the inverter 20 through the relay contact 82a of the relay 82. [ Here, the relay contact 82a is turned on when the current flowing through the relay coil 82b is less than the predetermined threshold value, and is turned off when the current exceeds the threshold. The configuration of the present embodiment other than the above is the same as that of the first embodiment (Fig. 1).

In the above configuration, when the DC voltage VC is within the normal range, almost no current flows in the abnormal voltage detection / discharge circuit 10, so that the detection signal voltage VA becomes almost 0 [V]. Therefore, the transistor 84 is turned off, almost no current flows through the relay coil 82b, and the relay coil 82b is turned on. As a result, the control power supply voltage VCC is supplied to the VCC terminal of the inverter 20, and the inverter 20 turns on / off the switching elements (not shown) in the inverter 20 to generate three-phase AC voltages MU, MV and MW To the motor (30).

On the other hand, when the DC voltage VC becomes higher than the breakdown voltage VB of the Zener diode 12, the current flowing in the abnormal voltage detection / discharge circuit 10 is proportional to " VC-VB ". When the DC voltage VC becomes higher and the detection signal voltage VA becomes equal to or higher than the base-emitter saturation voltage of the transistor 84, the transistor 84 is turned on. When a current equal to or higher than the threshold value is applied to the relay coil 82b, the relay contact 82a is turned off. As a result, the control power supply voltage VCC is not supplied to the inverter 20, and the output of the three-phase AC voltages MU, MV, and MW also stops.

As described above, according to the present embodiment, the on / off state of the inverter 20 can be switched on the basis of the direct-current voltage VC similarly to the first to fourth embodiments, The same effect can be obtained.

[Sixth Embodiment]

Next, the configuration of the motor driving apparatus according to the sixth embodiment of the present invention will be described with reference to a block diagram shown in Fig.

In the present embodiment, the abnormal voltage detection and discharge circuit 120 is a circuit in which the zener diode 12, the resistor 14 and the relay coil 19 are connected in series and the relay coil 19 is connected to the GND potential . In addition, the stop / return control circuit 90 shown in Fig. 8 is applied instead of the stop / return control circuit 80 (see Fig. 7) of the fifth embodiment. The stop / return control circuit 90 has a relay contact 92 which is switched on / off by a current flowing in the relay coil 19. [ The control power supply voltage VCC is applied to one end of the relay contact 92 and the VCC terminal of the inverter 20 is connected to the other end.

The relay contact 92 is turned on when the current flowing through the relay coil 19 is less than the predetermined threshold, and is turned off when the current exceeds the threshold. As is well known, the relay coil 19 generates a magnetic flux when an electric current flows, and the relay contact 92 is driven by this magnetic flux. Therefore, in the present embodiment, the "magnetic flux generated by the relay coil 19" is the "detection signal" and the stop / return control circuit 90 has the relay contact 92, (20). The configuration of the present embodiment other than the above is the same as that of the fifth embodiment (Fig. 7).

In the above configuration, when the DC voltage VC is within the normal range, almost no current flows through the abnormal voltage detection and discharge circuit 120, and the relay contact 92 is turned on. As a result, the control power supply voltage VCC is supplied to the VCC terminal of the inverter 20, and the inverter 20 turns on / off the switching elements (not shown) in the inverter 20 to generate three-phase AC voltages MU, MV and MW To the motor (30).

On the other hand, when the DC voltage VC becomes equal to or higher than the breakdown voltage VB of the Zener diode 12, a current flows to the abnormal voltage detection and discharge circuit 120. [ When the DC voltage VC becomes higher and the current flowing through the relay coil 19 becomes equal to or higher than the threshold value, the relay contact 92 is turned off. As a result, the control power supply voltage VCC is not supplied to the inverter 20, and the output of the three-phase AC voltages MU, MV, and MW also stops.

As described above, according to the present embodiment, the ON / OFF state of the inverter 20 can be switched on the basis of the DC voltage VC similarly to the first to fifth embodiments, The same effect can be obtained.

[Modifications]

The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are illustrative of the present invention in order to facilitate understanding, and are not necessarily limited to those having all the configurations described above. It is also possible to replace part of the constitution of any embodiment with the constitution of another embodiment, and it is also possible to add constitution of another embodiment to the constitution of any embodiment. It is also possible to delete some of the configurations of the embodiments or to add or replace other configurations. Possible modifications to the above embodiment are as follows, for example.

(1) In the first, second, and fifth embodiments (Figs. 1, 4, and 7), a resistor for stabilizing the operation of the transistors 42, 52, and 84 used may be added. FIG. 9 shows an example of a configuration in which a resistor is added to the first embodiment (FIG. 1). 9, the stop / return control circuit 40A provided in place of the stop / return control circuit 40 is configured such that the connection point A in the abnormal voltage detection / discharge circuit 10 and the transistor A resistor 41 is inserted between the base terminal of the transistor 42 and a resistor 43 is connected between the base terminal of the transistor 42 and the emitter terminal. In addition, the transistor 42 and the resistor 41 and 43, which are sealed in one package, are also distributed as " transistors "

(2) In the abnormal voltage detection and discharge circuit 10 of the first embodiment (Fig. 1), although the zener diode 12 and the two resistors 14 and 16 are connected in series, the zener diode 12 And one resistor may be connected in series to output the voltage of these connection points as the detection signal voltage VA.

[Overview of composition and effect]

As described above, in the first to sixth embodiments, when the DC voltage VC output from the condenser 6 exceeds a predetermined normal range (below the breakdown voltage VB), detection according to the DC voltage VC When the DC voltage VC is included in the normal range while discharging the capacitor 6 while outputting the signal VA, the impedance is higher than when the DC voltage VC exceeds the normal range And the DC voltage is supplied to the load (30) by converting the DC voltage (VC) into an AC voltage (MU, MV, MW) in accordance with the detection signal (VA) 50, 60, 70, 80, 90 for stopping the inverter (20, 130, 140, 150)

The abnormal voltage detecting and discharging circuit 10, 110, and 120 are both provided with a function of outputting the detection signal VA and a function of discharging the capacitor 6 when the DC voltage VC exceeds the normal range The electric charge accumulated in the condenser 6 can be appropriately discharged and can be constructed at a low cost.

In the first to sixth embodiments, the abnormal voltage detection and discharge circuit (10, 110, 120) includes a zener diode 12 and one or a plurality of And outputs a signal that has resistors (14, 16, 18) and whose signal level increases as the current flowing through the Zener diode (12) increases, as the detection signal (VA).

The circuit configuration of the abnormal voltage detection and discharge circuit 10, 110, and 120 can be simplified by using the detection signal VA as a signal whose signal level increases as the current flowing through the zener diode 12 becomes larger.

In the first to sixth embodiments, the stop / return control circuit 40, 50, 60, 70, 80, 90 is configured such that the DC voltage VC is higher than the breakdown voltage of the Zener diode 12 The inverters 20, 130, 140, and 150 are brought into a stopped state under the condition that the predetermined voltage VC4 is higher than the predetermined voltage VC2 (VB = VC2).

As a result, the discharge of the capacitor 6 when the direct-current voltage VC is equal to or higher than the predetermined voltage VC4 can be accelerated, and the time of the overvoltage state can be shortened.

In the first to sixth embodiments, the stop / return control circuit 40, 50, 60, 70, 80, 90 is configured such that, when the DC voltage (VC) (20, 130, 140, 150) to the operating state.

Thus, when the DC voltage VC is in the normal range, the inverters 20, 130, 140, and 150 can be returned to the operating state.

In the first embodiment, the inverter 20 controls the AC voltages MU, MV and MW based on the supplied control command voltage VSP and controls the control command voltage VSP, And the stop / return control circuit (40) is turned off when the control command voltage (VSP) is lower than the off voltage (Voff) And the control command voltage VSP is set to the OFF voltage Voff or lower in accordance with the detection signal VA.

Thereby, control according to the abnormal voltage can be performed using the control command voltage VSP.

In the second and third embodiments, the inverters 130 and 140 set the operation state and the stop state in accordance with the supplied two-value control signals SD and NSD, and the stop / (50, 60) sets the value of the control signal (SD, NSD) to a value corresponding to the stop state in accordance with the detection signal (VA).

Thereby, it is possible to perform control according to the abnormal voltage by using the binary control signals SD and NSD.

In the fourth embodiment, the inverter 150 determines whether or not an over-current is generated in the inverter 150 according to a voltage level of a predetermined over-current determination terminal (RS terminal), and when an over-current is generated And the stop / return control circuit 70 sets the voltage of the overcurrent judgment terminal (RS terminal) to the voltage corresponding to the overcurrent in accordance with the detection signal VA .

Thereby, control according to the abnormal voltage can be performed by using the overcurrent judgment terminal (RS terminal).

In the fifth and sixth embodiments, the inverter 20 operates by receiving supply of a control power supply voltage (VCC) of a voltage different from the DC voltage (VC), and the stop / (80, 90) has blocking portions (82a, 92) for cutting off supply to the control power supply voltage (VCC) for the inverter (20) in accordance with the detection signal (VA).

Thereby, supply of the control power supply voltage VCC is cut off, and control according to the abnormal voltage can be performed.

2: Commercial power supply
4: Converter
6: Capacitor
10: Abnormal voltage detection and discharge circuit
12: Zener diode
14, 16, 18: Resistors
19: Relay coil
20: Inverter
30: Motor (load)
40, 50, 60, 70, 80, 90: stop / return control circuit
41, 43: Resistors
42, 52, 84: transistor
44, 46: Resistors
48: Condenser
51: Resistors
61, 72, 74: Wires
82: Relay
82a: Relay contact (breaking part)
82b: relay coil
92: Relay contact (breaking part)
A, D: Connection point
SD, NSD: control signal
VA: detection signal voltage
VB: breakdown voltage
VC: DC voltage
VCC: Control power supply voltage
VD: Voltage corresponding to current consumption
VS: AC voltage

Claims (8)

An inverter control circuit comprising:
When the direct current voltage output from the capacitor exceeds a predetermined normal range, discharging the capacitor while outputting a detection signal corresponding to the direct current voltage, and when the direct current voltage is included in the normal range, An abnormal voltage detection and discharge circuit which has an impedance higher than that when it exceeds the normal range,
And a stop / return control circuit for generating a control command voltage for controlling an inverter for converting the direct-current voltage into an alternating-current voltage and supplying it to the load in accordance with the detection signal,
Wherein the abnormal voltage detection and discharge circuit comprises:
A signal having a zener diode and one or a plurality of resistors connected in series to the zener diode and having a higher signal level as the current flowing through the zener diode increases,
Wherein the stop / return control circuit sets the inverter to a stop condition on condition that the DC voltage is higher than a predetermined voltage higher than a breakdown voltage of the Zener diode,
Wherein the stop / return control circuit returns the inverter to the operating state when the DC voltage which has been abnormal is in the normal range,
The inverter controls the AC voltage based on the control command voltage. When the control command voltage exceeds the off-voltage of the inverter, the inverter enters an operation state. When the control command voltage becomes the off- State,
And the control command voltage becomes lower than or equal to the off voltage of the inverter when the DC voltage becomes equal to or higher than the predetermined voltage. delete delete delete delete delete delete delete

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