WO2019077689A1 - Air conditioner - Google Patents

Abstract

This air conditioner is provided with an electric motor (1), and a power conversion device (1) which uses a vector control method to perform power conversion. The power conversion device (1) is provided with: a pulse control unit (7) for outputting a pulse signal; a power conversion circuit (41) which uses the pulse signal to convert DC power into AC power; a current detection unit (6) which detects the current of the power conversion circuit (41); a vector control unit (8) for generating a command voltage for the pulse control unit (7); and a pulse stopping control unit (9) which generates a pulse stopping control signal for stopping the pulse signal in an interval determined using the current phase as a reference, and outputs the pulse stopping control signal to the pulse control unit (7). The vector control unit (8) starts operation of the pulse stopping control unit (9) if the motor current of the electric motor (1) is within a prescribed range of the motor current at the present rotational speed when there is no load.

Description

Air conditioner

The present invention relates to an air conditioner.

Various techniques have been developed to realize high efficiency and high output in a motor drive device of an air conditioner. For example, there has been disclosed a "180-degree conduction" technique of switching PWM (Pulse Width Modulation) control in a sine wave in the current flowing from the motor drive device to the motor. There is also disclosed a "120-degree conduction" technique in which PWM control is switched so that the current flowing to the motor is intermittent with reference to the phase of the induced voltage generated by driving the motor.

For example, in patent document 1, at the time of PWM control, the specification of the gate driver is satisfied by stopping PWM output for a certain period based on the motor current phase during motor drive by the vector control 180 degree conduction method. It is described that it is possible to reduce the switching loss of the power converter and to provide a highly efficient power converter.

JP, 2013-115955, A

The invention described in Patent Document 1 reduces the switching loss during PWM control by stopping the PWM output for a certain period based on the motor current phase during motor drive. However, the invention described in Patent Document 1 is limited to a specific condition (lower than rotational speed / lower than average motor current), and is not a technology that can achieve high efficiency in a wide range. Moreover, when stopping PWM output by DC fan control, it is necessary to consider the influence of disturbance such as wind unlike a compressor etc. If the PWM output is stopped regardless of the operating state, there is a possibility that the vibration may deteriorate or be stopped.

Then, this invention makes it a subject to provide the air conditioner which enables reduction of the switching loss accompanying a motor drive, and reduction of a motor copper loss, avoiding deterioration of a motor vibration and a motor stop.

In order to solve the above-mentioned subject, an air conditioner of the present invention is provided with an electric motor and a power converter which performs electric power conversion for driving the electric motor by PWM control using a vector control system. The power converter includes a pulse control unit that outputs a pulse signal for performing the PWM control, and a switch element having a three-phase configuration, and uses the pulse signal output from the pulse control unit. Power control circuit for converting direct current power to alternating current power, current detection unit for detecting current flowing in the power conversion circuit, and vector control based on current detected by the current detection unit, to the pulse control unit The pulse is generated in a section determined on the basis of the current phase of the power conversion circuit in order to stop the vector control unit generating the command voltage and the positive and negative switch elements of the predetermined phase of the power conversion circuit. And a pulse stop control unit for generating a pulse stop control signal for stopping the signal and outputting the pulse stop control signal to the pulse control unit. The vector control unit starts the operation of the pulse stop control unit if the motor current of the motor is within a predetermined range with respect to the motor current at no load of the current rotational speed.

Other means will be described in the form for carrying out the invention.

According to the present invention, it is possible to reduce switching loss and motor copper loss associated with driving of a motor while avoiding deterioration of motor vibration and stop of the motor.

It is a block diagram which shows the circuit structure of the power converter device of the PWM control system in this embodiment. It is a front view of the indoor unit of the air conditioner in this embodiment, an outdoor unit, and a remote control. It is a wave form diagram which shows the relation of the exchange voltage which flows into a motor at the time of normal operation, exchange current, and a pulse signal. FIG. 7 is a waveform diagram showing a relationship between an AC voltage, an AC current, and a pulse signal flowing through the motor during intermittent energization operation and a phase pulse stop control signal. It is a wave form diagram showing the relation of U phase voltage, U phase current, and a pulse signal at the time of driving an actual machine provided with a power conversion device. It is a characteristic view showing the relation of the power conversion circuit loss to the phase pulse stop section (open phase section), the motor loss, and the total loss which added them by the power converter of this embodiment. It is a graph which shows the execution field and hysteresis field of intermittent energization operation at the time of applying to a DC fan. It is a graph which shows the execution field and hysteresis field of intermittent energization operation at the time of applying to a compressor. It is a figure which shows the execution area | region and hysteresis area | region of the intermittent electricity supply operation | movement defined by the modulation rate. It is a figure which shows the execution area | region and hysteresis area | region of the intermittent electricity supply operation | movement which were defined by the rotational speed. It is a figure which shows the execution area | region and hysteresis area | region of intermittent electricity supply operation | movement which were defined by external temperature. It is a graph which shows the phase adjustment method when the intermittent energization is stopped and when it permits.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

"Overview"
The power conversion device according to the present embodiment is a power conversion circuit (inverter) that converts DC power into AC power using a pulse signal of PWM control, and detects a current flowing in the power conversion circuit to vector the power conversion circuit. And a vector control unit for controlling.

The power converter further includes an open phase section for stopping the switch elements of the upper and lower arms in phase by stopping the pulse signal of the section determined based on the zero crossing point of the current phase flowing through the power conversion circuit. Thus, the power conversion device can reduce the switching loss by reducing the number of switchings at the time of PWM control. Furthermore, by providing the open phase section, the power conversion device can acquire accurate position information of the magnet position of the motor by the zero crossing point of the current phase. As a result, stable vector control can be performed to improve the efficiency of the power conversion circuit (inverter) and the motor.

Hereinafter, embodiments of a power conversion device according to the present invention will be described in detail with reference to the drawings. In all the drawings for describing each embodiment, the same component is attached with the same symbol in principle, and the repeated explanation is omitted.

FIG. 1 shows a circuit configuration of a power conversion device 1 of a PWM control method according to the present embodiment.
In the power conversion device 1 of the present embodiment, as shown in FIG. 1, in the case where the AC motor 3 which is a permanent magnet synchronous motor is driven by vector control by the power conversion circuit 4 consisting of a three phase inverter driven by PWM control. A control method when a phase pulse stop section (that is, an open phase section) is provided in the pulse signal of the power conversion circuit 4 will be described.

Circuit configuration of power converter
As shown in FIG. 1, the power conversion device 1 is configured to include a power conversion circuit 4, a phase current detection unit 6, and a control device 5. The power conversion circuit 4 is configured to include a three-phase inverter that converts DC power into AC power. The phase current detection unit 6 detects the motor current flowing through the AC motor (motor) 3 connected to the power conversion circuit 4. The control device 5 performs vector control using a pulse signal that performs PWM control based on the phase current information (current) α detected by the phase current detection unit 6. A DC voltage Vd is applied to the power conversion circuit 4 by the power supply 2.

Further, the power conversion circuit 4 is configured to include a power conversion main circuit 41 and a gate driver 42. The gate driver 42 generates a gate signal supplied to an IGBT (Insulated Gate Bipolar Transistor) of the power conversion main circuit 41 based on the pulse signal γ from the pulse control unit 7. The power conversion main circuit 41 is composed of switching elements Q1 to Q6 of a three-phase configuration in which an IGBT and a diode are connected in parallel in the reverse direction. The power conversion main circuit 41 has U-phase, V-phase, and W-phase switching legs, and converts DC power into AC power using the pulse signal γ output from the pulse control unit 7.

The U-phase switching leg is configured by connecting switching elements Q1 and Q2 in series between the positive electrode and the negative electrode. The collector of switching element Q1 is connected to the positive electrode, and the emitter of switching element Q2 is connected to the collector of switching element Q2. The emitter of the switching element Q2 is connected to the negative electrode. A connection node between the emitter of switching element Q1 and the collector of switching element Q2 is connected to the U-phase coil of AC motor 3. In the present embodiment, a voltage at a connection node between the emitter of the switching element Q1 and the collector of the switching element Q2 is referred to as a voltage Vu. The current flowing through the U-phase coil of the AC motor 3 is referred to as a U-phase alternating current Iu.

The pulse signal GPU + output from the gate driver 42 is applied to the gate of the switching element Q1. The pulse signal GPU- output from the gate driver 42 is applied to the gate of the switching element Q2.

The switching leg of the V phase is configured by connecting switching elements Q3 and Q4 in series between the positive electrode and the negative electrode. The collector of switching element Q3 is connected to the positive electrode, and the emitter of switching element Q3 is connected to the collector of switching element Q4. The emitter of switching element Q4 is connected to the negative electrode. A connection node between the emitter of switching element Q3 and the collector of switching element Q4 is connected to the V-phase coil of AC motor 3.

Pulse signals output from the gate driver 42 are applied to the gates of the switching elements Q3 and Q4, respectively.

The switching leg of the W phase is configured by connecting switching elements Q5 and Q6 in series between the positive electrode and the negative electrode. The collector of switching element Q5 is connected to the positive electrode, and the emitter of switching element Q5 is connected to the collector of switching element Q6. The emitter of switching element Q6 is connected to the negative electrode. A connection node between the emitter of switching element Q5 and the collector of switching element Q6 is connected to the W-phase coil of AC motor 3.

Pulse signals output from the gate driver 42 are applied to the gates of the switching elements Q5 and Q6, respectively.

Further, the control device 5 is configured to include a pulse control unit 7, a vector control unit 8, and a pulse stop control unit 9. The pulse control unit 7 supplies a pulse signal γ controlled based on the applied voltage command (command voltage) V ^* to the gate driver 42 to perform PWM control. The vector control unit 8 performs vector control using the phase current information α detected by the phase current detection unit 6 to calculate an applied voltage command V ^* . The pulse stop control unit 9 is a phase pulse stop control signal for stopping the pulse signal γ of the phase pulse stop section (open phase section) δ near the current zero cross based on the phase information (current phase) of the current calculated by vector control. (Pulse stop control signal) β is output to the pulse control unit 7. The phase pulse stop control signal (pulse stop control signal) β stops the switching elements on the positive side and the negative side of the predetermined phase of the power conversion circuit 4.

Here, the vector control unit 8 is described, for example, in Non-Patent Document 1 (Sakamoto et al., “Simple Vector Control of Position Sensorless Permanent Magnet Synchronous Motor for Home Appliances”) Theory of Electrical Engineering D, Vol. 124, No. 11 (2004) pp. 1131-3140) and Non-Patent Document 2 (Tobari et al., "Study of New Vector Control Method for Permanent Magnet Synchronous Motor for High Speed," Electrology D, Vol. 129, Vol. 1, No. 1 (2009) pp. 36-45) As described in, the inverter output current is detected, three-phase to two-phase conversion (dq conversion; direct-quadrature conversion) is fed back to the control system, and the two-phase to three-phase conversion is performed again to drive the inverter It can be realized by using general vector control, and the control method is not specified. Therefore, since the operation of the vector control unit 8 is a known technique, the detailed description will be omitted.

FIG. 2 is a front view of the indoor unit 100, the outdoor unit 200, and the remote control Re of the air conditioner A in the present embodiment.

As shown in FIG. 2, the air conditioner A is called a so-called room air conditioner. The air conditioner A includes an indoor unit 100, an outdoor unit 200, a remote controller Re, and the power conversion device 1 (not shown in FIG. 2) shown in FIG. The indoor unit 100 and the outdoor unit 200 are connected by a refrigerant pipe 300, and the air in the room where the indoor unit 100 is installed is air-conditioned by a known refrigerant cycle. Moreover, the indoor unit 100 and the outdoor unit 200 mutually transmit and receive information via a communication cable (not shown). Furthermore, the outdoor unit 200 is connected by a wire (not shown), and an AC voltage is supplied via the indoor unit 100. The power conversion device 1 (see FIG. 1) is included in the outdoor unit 200, and converts alternating current power supplied from the indoor unit 100 side into direct current power.

The remote control Re is operated by the user, and transmits an infrared signal to the remote control transmission / reception unit Q of the indoor unit 100. The contents of the infrared signal are commands such as an operation request, a change of the set temperature, a timer, a change of the operation mode, and a stop request. The air conditioner A performs the air conditioning operation such as the cooling mode, the heating mode, and the dehumidifying mode based on the instruction of the infrared signals. Also, the indoor unit 100 transmits data such as room temperature information, humidity information, and electricity cost information from the remote control transmission / reception unit Q to the remote control Re.

The operation of the power conversion device 1 mounted on the air conditioner A will be described. The power conversion device 1 converts the DC voltage Vd supplied from the power supply 2 into an AC again to drive an AC motor 3 (not shown in FIG. 2). The AC motor 3 (not shown) is a DC fan motor, but may be applied to a compressor motor.

波形 Waveform at normal operation》
Here, in order to clarify PWM control at the time of intermittent electricity supply operation | movement by the power conversion device 1, PWM control at the time of normal operation is demonstrated using FIG. FIG. 3 is a waveform diagram showing the relationship between AC voltage, AC current, and pulse signal flowing in the AC motor 3 in the comparative example, the horizontal axis representing voltage phase, and the vertical axis representing each level of voltage, current and pulse signal. ing.

As shown in the first graph of FIG. 3, the control device 5 compares the PWM carrier signal with the applied voltage command V ^* to generate a PWM pulse signal (pulse signal γ) in the pulse control unit 7. Further, the command value of the applied voltage command V ^* is obtained by the calculation of the vector control unit 8 based on the phase current information α detected by the phase current detection unit 6. Here, acquisition of the phase current information α by the phase current detection unit 6 is, for example, directly detecting an AC output current by CT (Current Transformer) as disclosed in FIG. 1 of JP-A-2004-48886. Alternatively, as disclosed in FIG. 12 of the same publication, current information of a DC bus may be acquired by a shunt resistor, and a phase current may be reproduced based on the current information.

Next, the relationship between the AC voltage and AC current supplied from the power conversion device 1 to the AC motor 3 during normal operation and the pulse signal will be described in detail with reference to FIG. The first graph of FIG. 3 shows the PWM carrier signal and the applied voltage command V ^* , and shows the U-phase applied voltage command Vu ^* as a representative. Here, θv indicates a voltage phase with reference to the U phase.

In the PWM control method, as shown in the first graph of FIG. 3, the pulse control unit 7 generates the third graph of FIG. 3 based on the U-phase applied voltage command Vu ^* and the triangular wave carrier signal (PWM carrier signal). The pulse signals GPU + and GPU− shown are generated, and the pulse signals GPU + and GPU− are output to the gate driver 42 for driving the power conversion main circuit 41. The pulse signal GPU + is voltage-converted by the gate driver 42 and applied to the gate of the switching element Q1 on the upper side of the U phase. The pulse signal GPU- is voltage-converted by the gate driver 42 and applied to the gate of the switching element Q2 on the lower side of the U phase. That is, the pulse signal GPU + and the pulse signal GPU- are opposite in polarity (1, 0).

When the power conversion main circuit 41 performs PWM control by the pulse signals GPU + and GPU−, a U-phase alternating current Iu as shown in the second graph of FIG. 3 flows in the alternating current motor 3. Here, φ indicates the phase difference between the voltage and the current.

The vector control unit 8 performs vector control based on phase current information α including the U-phase alternating current Iu to control the voltage amplitude and the phase difference φ between the voltage and the current.

As shown in FIG. 3, in PWM control during normal operation, switching operation is always performed during one cycle of voltage and current, and 180 degrees of conduction are conducted, and there is a period of 120 degrees conduction method in which there is a period in which switching operation stops. The number of switching times is larger than that of the 150 ° conduction method. Therefore, at 180 degree conduction, the switching loss resulting from this increases.

<< Waveform at the time of intermittent energization operation >>
In the following description, the operation of the pulse stop control unit 9 (see FIG. 1) for temporarily stopping the switching operation of the pulse signal for performing the PWM control will be described with reference to FIG. 1 and FIG.

FIG. 4 is a waveform diagram showing a relationship between an AC voltage, an AC current and a pulse signal flowing in the AC motor 3 and a phase pulse stop control signal in the present embodiment, in which the horizontal axis represents voltage phase and the vertical axis represents voltage; The respective levels of the current, the pulse signal and the open phase control signal (phase pulse stop control signal) are shown. That is, FIG. 4 is a waveform chart at the time of intermittent energization operation shown in comparison with the waveform chart at the time of normal operation of FIG.

As shown in the fourth graph of FIG. 4, the pulse stop control unit 9 generates the phase φ and the phase φ + π with reference to the zero-crossing point φ of the current phase controlled by the vector control as shown in the following equation (1) Further, a phase pulse stop control signal (open phase control signal) β for stopping switching of both the pulse signals GPU + and GPU− is output to the pulse control unit 7 during the phase pulse stop interval (open phase interval) δ. The phase pulse stop control signal β outputs “0” when stopping switching of both the pulse signals GPU + and GPU−, and outputs “1” when performing switching of the PWM control method without stopping the switching.

 
 
 
 

That is, as can be seen from the equation (1), assuming that φ is a phase difference between the voltage and the current, and δ is a phase pulse stop interval (open phase interval), the voltage phase θv with reference to the U phase is φ−δ / When 2 <θv <φ + δ / 2 and φ + π−δ / 2 <θv <φ + π + δ / 2, switching by the pulse signals GPU + and GPU− is stopped. And switching by pulse signal GPU + and GPU- is performed at other times.

Therefore, in the output state from the pulse control unit 7, both of the pulse signals GPU + and GPU− are turned off in the phase pulse stop interval δ of the phase pulse stop control signal β. Therefore, as shown in the third graph of FIG. 4, the pulse control unit 7 outputs a signal train of pulse signals paused in the phase pulse stop interval δ. In other words, the phase pulse stop interval (open phase interval) δ is set twice over one cycle of the voltage and current. In addition, in the case of the configuration of the present embodiment, the target PWM control modulation method is not limited to the sine wave PWM control method, and the same phase pulse can be used in the two-phase modulation PWM control method or the third harmonic addition PWM control method. It is possible to provide the stop section δ.

As described above, the pulse signals GPU + and GPU- provided with a period for stopping the switching operation by the pulse stop control unit 9 reference the applied voltage phase and the induced voltage phase of the AC motor 3 in the switching stop period and the switching operation period. The shape is not provided. That is, the switching stop period and the switching operation period of the pulse signals GPU + and GPU− are set with reference to the zero cross point of the current phase.

In other words, during normal operation, since the pulse signal is based on the voltage phase of the induced voltage, as shown in the third graph of FIG. 3, the pulse signal train has an ON / OFF duty before and after the zero cross point of voltage. Is symmetrical. However, in the intermittent energization operation, since the phase pulse stop section δ is provided based on the current phase (that is, because it is not a pulse signal based on the voltage phase), as shown in the third graph of FIG. Before and after the zero crossing point of the voltage, the ON / OFF duty of the pulse signal train is not symmetrical. That is, in the present embodiment, the ON / OFF duty of the pulse signal train is asymmetrical before and after the current zero cross point.

Thus, at the time of the intermittent energization operation, the phase pulse stop section δ is provided in the section including the zero cross point of the current, so as shown in the third graph of FIG. The front and rear pulse signal trains A and B have an asymmetrical shape. From this, when the phase pulse stop section δ is provided in the section including the zero cross point of the current, the present embodiment is implemented by observing whether the pulse signals before and after the phase pulse stop section δ are asymmetrical. It can be easily determined whether or not the intermittent energization operation of the above is applied.

波形 Waveform when driving by actual machine》
FIG. 5 is a waveform diagram showing the relationship between the U-phase voltage, the U-phase current, and the pulse signal when driving an actual device provided with the power conversion device 1 of the present embodiment, the horizontal axis representing voltage phase and the vertical axis The respective levels of voltage, current, and pulse signal are shown. That is, FIG. 5 is a method in which the phase pulse stop section is provided in the vicinity including the zero cross point of the current due to the intermittent energization operation of this embodiment, and the phase pulse stop section is set in the two-phase modulation type PWM control method Shows the voltage, current and pulse signal when driving

The first graph of FIG. 5 shows U-phase terminal voltage Vun of the power conversion main circuit 41, the second graph of FIG. 5 shows U-phase AC current Iu flowing through the AC motor 3, and the third graph of FIG. Is shown.

As shown in the third graph of FIG. 5, the switching signals of the pulse signals GPU + and GPU− are both off in the section (indicated by δ) sandwiched by the one-dot chain line, and the phase pulse stop section δ is set. Can be confirmed. In addition, since the phase pulse stop section δ is set, it can be confirmed at the same time that the U-phase alternating current Iu becomes zero in the section sandwiched by the one-dot chain line.

<< The effect of intermittent power operation >>
FIG. 6 is a characteristic diagram showing the relationship between the power conversion circuit loss, the motor loss and the total loss obtained by adding them to the phase pulse stop interval (open phase interval) δ by the power conversion device 1 of the present embodiment. The axis represents a phase pulse stop section (open phase section) δ, and the vertical axis represents a loss. That is, FIG. 6 shows the characteristics of the total loss obtained by combining the phase pulse stop interval δ set by the pulse stop control unit 9 and the loss of the power conversion circuit 4, the loss of the AC motor 3, and these two losses.

As shown in FIG. 6, the loss (power conversion circuit loss) of the power conversion circuit 4 of the present embodiment is reduced because the number of times of switching decreases as the phase pulse stop interval δ increases. Do. Further, the loss (motor loss) of the AC motor 3 is increased because the harmonic component of the current is increased by providing the phase pulse stop section δ. Furthermore, since the increase of the harmonic component of the current becomes remarkable due to the increase of the phase pulse stop interval δ, the increase of the loss (motor loss) of the AC motor 3 resulting from this also becomes remarkable. Therefore, as shown in FIG. 6, there is a phase pulse stop interval δ _opt in which the total loss obtained by adding these two losses (power conversion circuit loss and motor loss) is minimized. By setting the phase pulse stop interval δ to this phase pulse stop interval δ _opt , it is possible to reduce the overall loss of the power conversion device 1.

As described above, by using the pulse stop control unit 9, it is possible to reduce the number of switching times of the pulse signal for performing the PWM control. In other words, when the pulse stop control unit 9 performed by the control of the microcomputer is configured by software, the configuration of the power conversion circuit 4 of the comparative example is not changed, and the addition of new hardware is not performed. It becomes possible to achieve high efficiency. Further, since the switching operation is stopped near the zero cross of the current of the AC motor 3, it is possible to suppress an increase in torque pulsation with respect to the 150-degree conduction method.

However, the vector control method of the present embodiment is position sensorless simple vector control, and is simplified based on conventional vector control. This position sensorless simple vector control can exhibit the same performance as ideal vector control except for a transient state in which the speed and load torque fluctuate. In other words, position sensorless simple vector control can not be expected to perform as well as ideal vector control in transient conditions in which speed and load torque change. In such a transient state, if the PWM output is stopped by the intermittent current supply operation, the vibration may be deteriorated or stopped.

According to the present invention, the intermittent energization operation is performed only when it is determined that the motor is stably driven, thereby preventing the deterioration of the motor vibration and the stop of the motor.

FIG. 7 is a graph showing an execution area and a hysteresis area of the intermittent energization operation when applied to a DC fan.
The horizontal axis of the graph indicates the number of rotations per minute, that is, the rotation speed. The vertical axis of the graph indicates the current flowing through the AC motor 3. The Im reference value is a current value which is a high frequency rotation speed at no load. The motor current Im can be calculated by the following equation (2).

 
 

The solid line graph shows the relationship between the actual rotation speed N and the motor current Im at no load.
The middle broken line graph shows the relationship between the actual rotation speed N and the motor current Im when the predetermined positive load is applied to the AC motor 3, and is a value higher than the solid line graph by the current I _r2 . The fine broken line graph shows the relationship between the actual rotation speed N and the motor current Im when a larger positive load is applied to the AC motor 3, which is higher than the medium broken line graph by the current _Ih2 . For example, when a headwind blows on the DC fan, a positive load is applied to the AC motor 3 and swings in the direction of a medium broken line graph or a fine broken line graph.

The alternate long and short dash line graph indicates the relationship between the actual rotation speed N and the motor current Im when the predetermined negative load is applied to the AC motor 3, and is a value lower than the solid line graph by the current I _r1 . The rough broken line graph shows the relationship between the actual rotation speed N and the motor current Im when a further negative load is applied to the AC motor 3, which is lower than the medium broken line graph by the current _Ih1 . For example, when a forward wind blows on a DC fan, a negative load is applied to the AC motor 3 and swings in the direction of a dashed dotted line graph or a rough broken line graph.

Execution region Z ₁ is a region of dense hatching indicates a region to begin executing the intermittent power supply operation. The execution region Z ₁ is a region between the dashed graph and dashed line graphs moderate. That is, a load within a predetermined range is applied to the motor. At this time, the control device 5 starts the intermittent energization operation. In addition, since FIG. 7 is a case where it applies to a DC fan, it is thought that the load concerning AC motor 3 is substantially the same in positive / negative. Therefore, the current I _r1 and the current I _r2 are set equal.

Execution region Z ₁ further is directed to Im lower limit value or more regions plus current I _h1 to the limiter. The phase current detection unit 6 of the present embodiment detects a current by a shunt resistor (not shown). Therefore, there is a detectable Im lower limit. Therefore, there is provided a lower limit to execution region Z _1.

Hysteresis region Z ₂ is a region of the thin hatching, when running intermittent energization operation, it indicates a region to continue the execution. Hysteresis region Z ₂ is a region between the fine broken line graph and long dashed line graph. The control device 5, when the offset or hysteresis to the execution area Z _1, which stops the intermittent power supply operation. By providing the hysteresis, it is possible to prevent chattering at the boundary of the execution region Z _1.

In addition, since FIG. 7 is a case where it applies to a DC fan, it is thought that the load concerning AC motor 3 is substantially the same in positive / negative. Therefore, the current I _h1 and the current I _h2 are set equal.
Hysteresis region Z ₂ are as Im lower limit limiter or more regions.

Furthermore the execution region Z ₁ and the hysteresis region Z _2, are a high-frequency rotational speed following areas.

FIG. 8 is a graph showing an execution region and a hysteresis region of the intermittent energization operation when applied to a compressor.
The solid line shows the relationship between the actual rotation speed N and the motor current Im at no load.

The middle broken line shows the relationship between the actual rotation speed N and the motor current Im when the predetermined positive load is applied to the AC motor 3, and is a value higher than the solid line by the current I _r4 . The fine broken line shows the relationship between the actual rotation speed N and the motor current Im when a larger positive load is applied to the AC motor 3, which is higher than the medium broken line by the current I _h4 . When the non-loaded compressor is rotated, a positive load is applied to the AC motor 3 in many cases, so that it swings in the direction of a medium broken line or a fine broken line.

The alternate long and short dash line indicates the relationship between the actual rotation speed N and the motor current Im when a predetermined negative load is applied to the AC motor 3, and is a value lower than the solid line by the current I _r3 . The rough broken line shows the relationship between the actual rotation speed N and the motor current Im when a further large negative load is applied to the AC motor 3, which is a value lower than the middle broken line by the current _Ih3 . When there is little negative load on the AC motor 3 when the compressor is rotated, the current I _r3 is set smaller than the current I _r4 and the current I _h3 is set smaller than the current I _h4 .

Execution region Z ₃ is a region of dense hatching indicates a region to begin executing the intermittent power supply operation. The execution region Z ₃ is an area between the medium dashed and dashed line. That is, a load within a predetermined range is applied to the motor. At this time, the control device 5 starts the intermittent energization operation. In addition, since FIG. 8 is a case applied to a compressor, it is considered that the load applied to the AC motor 3 is mostly positive. Therefore, the current I _r2 is set larger than the current I _r1 .

Execution region Z ₃ further has a value or more regions plus current I _h3 in Im lower limit limiter. The phase current detection unit 6 of the present embodiment detects a current by a shunt resistor (not shown). Therefore, there is a detectable Im lower limit. Therefore, there is provided a lower limit to execution region Z _3.

Hysteresis region Z ₄ is a region of the thin hatching, when running intermittent energization operation, it indicates a region to continue the execution. Hysteresis region Z ₄ is a region between the fine broken line and long dashed line. The control device 5, when the offset or hysteresis to the execution region Z _3, has stopped intermittent energization operation. In addition, since FIG. 8 is a case where it applies to a compressor, it is thought that the case where it applies to the AC motor 3 is mostly positive. Therefore, the current I _h4 is set larger than the current I _h3 .

Hysteresis region Z ₂ are as Im lower limit limiter or more regions.
Furthermore the execution region Z ₁ and the hysteresis region Z _2, are a high-frequency rotational speed following areas.

FIG. 9 is a diagram showing an execution region and a hysteresis region of the intermittent energization operation defined by the modulation factor.
When the modulation factor exceeds M ₁ , the intermittent energization operation starts. When the modulation rate becomes smaller than (M ₁ -M _h ) after M ₁ is exceeded, the intermittent power supply operation is stopped.

The intermittent energization operation is stopped when the modulation factor exceeds M ₂ during the intermittent energization operation. When the modulation rate becomes smaller than (M ₂ -M _h ) after M ₂ is exceeded, the intermittent power supply operation is started. Thus, the intermittent energization operation is performed when the modulation rate is in the middle range, and the intermittent energization operation is stopped when the middle zone is deviated beyond a predetermined hysteresis. Thereby, it can be more accurately determined that the motor is stably driven.

FIG. 10 is a diagram showing an execution region and a hysteresis region of the intermittent energization operation defined by the rotational speed.
When the rotational speed exceeds R ₁ , the intermittent energization operation starts. If the rotational speed becomes smaller than (R ₁ -R _h ) after the rotational speed exceeds R ₁ , the intermittent energization operation is stopped.

When the rotational speed exceeds M ₂ during the intermittent energization operation, the intermittent energization operation is stopped. In after the rotational speed has exceeded the R _2, when it becomes smaller than the (R ₂ -R _h), the intermittent energization operation is started. As described above, the intermittent energization operation is performed when the rotational speed is in the middle range, and the intermittent energization operation is stopped when the middle range is deviated beyond a predetermined hysteresis. Thereby, it can be more accurately determined that the motor is stably driven.

FIG. 11 is a diagram showing an execution region and a hysteresis region of the intermittent energization operation defined by the outside air temperature.
When the outside air temperature exceeds T _1, the intermittent energization operation is started. When the outside air temperature becomes lower than (T ₁ -T _h ) after T ₁ is exceeded, the intermittent energization operation is stopped.

During the intermittent energization operation, when the outside air temperature exceeds T _2, the intermittent power supply operation is stopped. In after the outside air temperature exceeds T _2, when it becomes less than (T ₂ -T _h), the intermittent energization operation is started. Thus, the intermittent energization operation is performed when the outside air temperature is in the middle range, and the intermittent energization operation is stopped when the middle zone is deviated beyond the predetermined hysteresis. Thereby, it can be more accurately determined that the motor is stably driven.

FIG. 12 is a graph showing a phase adjustment method in the case where the intermittent energization is stopped and in the case where it is permitted.
The intermittent power supply operation is permitted before time t0. At this time, the control device 5 performs the intermittent power supply operation of the power conversion circuit 4 at the intermittent phase θ.

At time t0, control device 5 determines that the intermittent energization operation is stopped. After that, the control device 5 gradually decreases the intermittent phase until time t1, and stops the intermittent power supply operation at time t1.
At time t2, the control device 5 determines the start of the intermittent power supply operation. After this, the control device 5 gradually increases the intermittent phase until time t3 and performs intermittent current supply operation at intermittent phase θ at time t3. As described above, since the intermittent phase is gradually changed, it is possible to alleviate the switching shock accompanying the start and stop of the intermittent energization operation.

(Modification)
The present invention is not limited to the embodiments described above, but includes various modifications. For example, the above-described embodiments are described in detail to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. It is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is also possible to add, delete, and replace other configurations for part of the configurations of the respective embodiments.

Each of the configurations, functions, processing units, processing means, etc. described above may be realized partially or entirely by hardware such as an integrated circuit. Each configuration, function, etc. described above may be realized by software by the processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files that implement each function can be placed in a memory, hard disk, recording device such as a solid state drive (SSD), or recording medium such as a flash memory card or a digital versatile disk (DVD) it can.

In each embodiment, control lines and information lines indicate what is considered to be necessary for the description, and not all control lines and information lines in a product are shown. In practice, almost all configurations may be considered to be connected to each other.
As a modification of the present invention, there are, for example, the following (a) to (e).

(A) The invention is not limited to a DC fan or a motor of a compressor, and may be applied to any motor.
(B) The execution region may not have to be lower than or equal to the high frequency rotation number.
(C) Determining stable driving is not limited to the area indicated by the motor current Im and the number of revolutions per minute, but may be the area indicated by the torque and the number of revolutions per minute.
The torque value is calculated by the sum of the torque theoretical formula calculated value and the offset value, as shown in equation (3).

Further, the calculated value of the torque theoretical equation is calculated by equation (4).

That is, since the torque is uniquely calculated by the motor current Im, the torque can be used instead of the motor current Im to determine whether or not stable driving is performed.
(D) Determining stable driving is not limited to the area indicated by the motor current Im and the number of revolutions per minute, but may be the area indicated by the modulation rate and the number of revolutions per minute. When the applied voltage is constant, the modulation factor can be uniquely calculated from the motor current Im.
(E) In addition to detecting the motor current flowing to the AC motor (motor), the current flowing to the power conversion circuit may be detected and used as the motor current.

1 power converter 2 power supply 3 AC motor (motor)
4 power conversion circuit 41 power conversion main circuit 42 gate driver 5 control device 6 phase current detection unit 7 pulse control unit 8 vector control unit 9 pulse stop control unit Q1 to Q6 switching element Vd DC voltage A air conditioner 100 indoor unit 200 outdoor unit Machine Re Remote control Q Remote control transmission / reception unit 300 Refrigerant piping α phase current information (current)
β-phase pulse stop control signal (pulse stop control signal)
γ pulse signal (PWM pulse signal)
Phase information δ phase pulse stop section (open phase section)
GPU + pulse signal GPU-pulse signal Iu U phase AC current φ phase difference

Claims (8)

1. Electric motor,
   A power conversion device that performs power conversion for driving the motor by PWM control using a vector control method;
   The power converter is
   A pulse control unit that outputs a pulse signal for performing the PWM control;
   A power conversion circuit including a three-phase switch element and converting DC power into AC power using the pulse signal output from the pulse control unit;
   A current detection unit that detects a current flowing through the power conversion circuit;
   A vector control unit that performs vector control based on the current detected by the current detection unit, and generates a command voltage to the pulse control unit;
   A pulse stop control signal for stopping the pulse signal in a section determined based on the current phase of the power conversion circuit to stop the positive and negative switch elements of the predetermined phase of the power conversion circuit; A pulse stop control unit that outputs the pulse stop control signal to the pulse control unit;
   Equipped with
   The vector control unit starts the operation of the pulse stop control unit if the motor current of the motor is within a predetermined range with respect to the motor current at no load of the current rotational speed.
   An air conditioner characterized by
2. When the operation of the pulse stop control unit is started, the vector control unit gradually increases a section for generating the pulse stop control signal from zero to the determined section.
   The air conditioner according to claim 1, characterized in that.
3. The vector control unit operates the pulse stop control unit when the motor current of the motor deviates from the predetermined range by exceeding the predetermined hysteresis amount when the pulse stop control unit is operated. Stop it,
   The air conditioner according to claim 1, characterized in that.
4. When the operation of the pulse stop control unit is stopped, the vector control unit gradually reduces the interval for generating the pulse stop control signal from the determined interval to zero.
   The air conditioner according to claim 3, characterized in that.
5. Electric motor,
   A power conversion device that performs power conversion for driving the motor by PWM control using a vector control method;
   The power converter is
   A pulse control unit that outputs a pulse signal for performing the PWM control;
   A power conversion circuit including a three-phase switch element and converting DC power into AC power using the pulse signal output from the pulse control unit;
   A current detection unit that detects the current of the power conversion circuit;
   A vector control unit that performs vector control based on the current detected by the current detection unit, and generates a command voltage to the pulse control unit;
   A pulse stop control signal for stopping the pulse signal in a section determined based on the current phase of the power conversion circuit to stop the positive and negative switch elements of the predetermined phase of the power conversion circuit; A pulse stop control unit that outputs the pulse stop control signal to the pulse control unit;
   Equipped with
   The vector control unit starts the operation of the pulse stop control unit if the torque of the motor is within a predetermined range with respect to the torque at no load of the current rotational speed.
   An air conditioner characterized by
6. The vector control unit stops the operation of the pulse stop control unit when the torque of the electric motor deviates from the predetermined range beyond the predetermined hysteresis amount while operating the pulse stop control unit. ,
   The air conditioner according to claim 5, characterized in that:
7. Electric motor,
   A power conversion device that performs power conversion for driving the motor by PWM control using a vector control method;
   The power converter is
   A pulse control unit that outputs a pulse signal for performing the PWM control;
   A power conversion circuit including a three-phase switch element and converting DC power into AC power using the pulse signal output from the pulse control unit;
   A current detection unit that detects the current of the power conversion circuit;
   A vector control unit that performs vector control based on the current detected by the current detection unit, and generates a command voltage to the pulse control unit;
   In order to stop positive and negative switch elements of a predetermined phase of the power conversion circuit, a pulse stop control signal is generated to stop the pulse signal in a section determined with reference to the current phase of the power conversion circuit. A pulse stop control unit that outputs the pulse stop control signal to the pulse control unit;
   Equipped with
   The vector control unit starts the operation of the pulse stop control unit if the modulation factor of the motor is within a predetermined range with respect to the modulation factor at the time of no load of the current rotational speed.
   An air conditioner characterized by
8. The vector control unit stops the operation of the pulse stop control unit if the modulation factor of the motor deviates from the predetermined range by exceeding the predetermined hysteresis amount while operating the pulse stop control unit. Let
   The air conditioner according to claim 7, characterized in that.

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