CN112242801A - Motor drive device, and refrigerator and refrigeration cycle device using same - Google Patents
Motor drive device, and refrigerator and refrigeration cycle device using same Download PDFInfo
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- CN112242801A CN112242801A CN202010679197.1A CN202010679197A CN112242801A CN 112242801 A CN112242801 A CN 112242801A CN 202010679197 A CN202010679197 A CN 202010679197A CN 112242801 A CN112242801 A CN 112242801A
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- 238000005057 refrigeration Methods 0.000 title claims description 21
- 230000010349 pulsation Effects 0.000 claims abstract description 12
- 230000000737 periodic effect Effects 0.000 claims abstract description 7
- 238000001514 detection method Methods 0.000 description 22
- 230000006835 compression Effects 0.000 description 16
- 238000007906 compression Methods 0.000 description 16
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
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- 230000005226 mechanical processes and functions Effects 0.000 description 7
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- 230000009467 reduction Effects 0.000 description 6
- 238000009499 grossing Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
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- 238000001816 cooling Methods 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 239000003507 refrigerant Substances 0.000 description 3
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/10—Arrangements for controlling torque ripple, e.g. providing reduced torque ripple
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
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- Control Of Motors That Do Not Use Commutators (AREA)
- Devices That Are Associated With Refrigeration Equipment (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The present invention provides a motor drive device (20), comprising: a brushless DC motor (4) that drives a load having a periodic pulsating torque; an inverter (3) for supplying electric power to the brushless DC motor (4); and a control unit (21) for controlling the inverter (3). The control unit (21) is configured to adjust the conduction angle of the brushless DC motor (4) during power supply from the inverter (3) to the brushless DC motor (4) according to the pulsation of the load.
Description
Technical Field
The present invention relates to a motor drive device, and a refrigerator and a refrigeration cycle device using the same.
Background
A conventional motor driving device is used for driving a load generated by torque pulsation, such as a compressor mounted in a refrigerator (see, for example, japanese patent application laid-open No. 2006-2732). As shown in fig. 10, the related art motor driving device includes: inverter 101, brushless DC motor 103 for driving compressor 102, rotation position determining means 104 for determining the rotation position of brushless DC motor 103, 1 st PWM generator 105, 2 nd PWM generator 106 having a higher on-time duty ratio than 1 st PWM generator 105, and selector 107 for selecting one of 1 st PWM mechanism and 2 nd PWM mechanism according to the rotation position of compressor 102. Then, the applied torque is corrected in accordance with the mechanical position of brushless DC motor 103, thereby suppressing the driving vibration of compressor 102.
Disclosure of Invention
The invention provides a motor driving device which can restrain driving vibration caused by torque pulsation when a load such as a compressor is driven and has high efficiency.
The motor driving device of the present invention includes: a brushless DC motor that drives a load having a periodic pulsating torque; an inverter for supplying electric power to the brushless DC motor; and a control unit for controlling the inverter. The control unit is configured to adjust an energization angle of the brushless DC motor in power supply from the inverter to the brushless DC motor in accordance with a ripple of torque of the load.
Drawings
Fig. 1 is a block diagram of a motor drive device according to embodiment 1.
Fig. 2 is a timing chart of the motor drive device.
Fig. 3A is a timing chart showing a case where the energization angle of the brushless DC motor in the motor driving device is 120 degrees.
Fig. 3B is a timing chart showing a case where the brushless DC motor in the motor drive device is energized at a wide angle wider than 120 degrees.
Fig. 3C is a timing chart showing a case where the brushless DC motor in the motor drive device is energized at a narrow angle of less than 120 degrees.
Fig. 4 is a load torque diagram of 1 cycle (1 revolution of the brushless DC motor) of the compressor of the motor drive device.
Fig. 5 is a diagram showing a position detection interval of the brushless DC motor when the compressor of the motor drive device is driven.
Fig. 6 is a diagram showing a conduction angle correction pattern according to embodiment 1.
Fig. 7 is a diagram showing the conduction angle of the brushless DC motor according to embodiment 1.
Fig. 8 is a diagram showing the speed ripple of the brushless DC motor.
Fig. 9 is a block diagram showing a refrigerator as an example of a refrigeration cycle apparatus according to embodiment 2.
Fig. 10 is a block diagram of a motor drive device of the related art.
Description of the reference numerals
1 AC power supply
2 rectification smoothing circuit
2c relay
3 inverter
4 brushless DC motor
5 compression Member (load)
6 compressor
7 condenser
8 pressure reducer
9 evaporator
10 position detecting part
11 speed detecting part
12 error detecting part
13 speed control part
13a PWM control unit
13b conduction angle control unit
14 process estimating unit
15 correction arithmetic unit
16 waveform generating part
17 drive part
18 refrigerator
19 food storage chamber
20 motor driving device
21 control part
Detailed Description
(knowledge and the like on which the present invention is based)
The inventors have conducted extensive studies to obtain a high-efficiency motor driving device capable of suppressing driving vibration due to torque ripple when a load such as a compressor is driven, and as a result, have obtained the following knowledge.
The conventional motor driving device of patent document 1 shown in fig. 10 detects a mechanical process in which the load torque of a load driven by brushless DC motor 103 varies based on a signal from rotational position determining unit 104. In the case of fig. 10, the load torque fluctuates due to mechanical steps such as compression and suction of the compressor 102 as a load. In accordance with the mechanical process of the compressor, either the 1 st PWM generator 105 or the 2 nd PWM generator 106 is selected to control the brushless DC motor 103.
Here, in the above configuration, the applied torque corresponding to the mechanical position of the compressor at which the load torque increases is corrected by increasing the on-time duty ratio of the PWM control according to the mechanical process of the compressor. This can suppress vibration caused by driving of the compressor 102. However, in such a configuration, the inventors have found that there are problems that: the occurrence of switching loss due to PWM control, and the increase of motor iron loss due to a high-frequency current component generated by high-frequency switching in PWM control.
The present inventors have therefore studied a motor driving device with high efficiency, which can suppress vibration during load driving without using PWM control, and have completed the present invention.
Hereinafter, each embodiment will be described with reference to the drawings. In the present embodiment, a motor driving device for driving a compressor in a refrigerator will be described as an example. However, a detailed description beyond necessity may be omitted. For example, a detailed description of already known contents or a repetitive description of substantially the same configuration may be omitted. This is to avoid that the description becomes more lengthy than necessary, which will be readily understood by the person skilled in the art.
It should be noted that the drawings and the following description of the embodiments are provided to enable those skilled in the art to sufficiently understand the present invention, and are not intended to limit the subject matter described in the claims.
(embodiment mode 1)
[1-1. Structure ]
Fig. 1 shows a block diagram of a motor drive device according to embodiment 1 of the present invention.
In fig. 1, an ac power supply 1 is a normal commercial power supply. In Japan, AC100V50Hz or 60 Hz. The rectifying/smoothing circuit 2 rectifies and smoothes the ac power supply 1, which is a commercial power supply, and converts the rectified and smoothed ac power supply into a dc voltage. The rectifying/smoothing circuit 2 has a relay 2c, and is configured to be capable of switching the output voltage 2 in stages by switching the rectifying method of the rectifying/smoothing circuit 2 between full-wave rectification and voltage-doubler rectification.
The inverter 3 is configured by a total of 6 switching elements 3a to 3f in which 2 switching elements connected in series are connected in parallel into 3 groups. The brushless DC motor 4 drives a load. In the example of the present embodiment, the brushless DC motor 4 drives the compression member 5 as a load. The inverter 3 is controlled by a control unit 21 described later. The brushless DC motor 4 is constituted by a stator having 3-phase windings and a rotor having permanent magnets. The 3-phase winding is connected to the connection points of the 2 switching elements of the inverter 3 connected in series.
The compression element 5 is used as a part of a refrigeration cycle. The compression member 5 has mechanical steps of suction, compression, and discharge of refrigerant gas. The load torques in these respective mechanical steps are greatly different from each other. The compression member 5 is connected to a shaft of a rotor of the brushless DC motor 4 as a load of the brushless DC motor 4. Therefore, the load torque during 1 rotation of brushless DC motor 4 greatly fluctuates.
The brushless DC motor 4 and the compression element 5 are housed in the same sealed container to constitute a compressor 6. The compressed refrigerant gas is sent from the discharge side of the compressor 6 to the condenser 7, and is returned to the suction side of the compressor 6 through the decompressor 8 and the evaporator 9. Thereby constituting a refrigeration cycle.
The motor drive device 20 of the present embodiment is configured by the brushless DC motor 4, the inverter 3, and the control unit 21, and drives the compressor 6 as a load.
Next, an example of the configuration of the control unit 21 will be described.
The control unit 21 receives information on the rotational position of the brushless DC motor 4 and a target speed, and outputs signals for driving the switching elements 3a to 3f of the inverter 3, thereby controlling the inverter 3.
The speed control unit 13 includes a PWM control unit 13a and a conduction angle control unit 13 b. The PWM control unit 13a adjusts the on-time duty ratios of the switching elements 3a to 3f of the inverter 3 to perform speed control. Conduction angle control unit 13b adjusts the conduction angle of brushless DC motor 4 (that is, the conduction angle at which the 3-phase winding of brushless DC motor 4 is conducted) by setting the timing at which switching elements 3a to 3f of inverter 3 are turned on and off.
The speed control by the PWM control unit 13a is mainly used in a driving state where the voltage applied to the brushless DC motor 4 is extremely low, such as at the time of startup. The conduction angle at this time, 120 degrees, is essential. In the motor drive device 20 of the present embodiment, the conduction angle is adjusted by the conduction angle control unit 13b by substantially fixing the PWM on-time duty of the PWM control unit 13a to 100% in a normal state. Thereby, the brushless DC motor 4 is controlled to be driven at a target speed. Here, the normal time means a driving time other than a starting time, a low-speed driving time, a low-load driving time, and the like of the brushless DC motor 4. The normal state in the device including the compressor 6 is a state in which the device operates in a normal refrigeration cycle operation state.
The process estimation unit 14 analyzes the load torque ripple of the compressor 6 (compression element 5) as the load, based on the speed ripple of the brushless DC motor 4 detected by the speed detection unit 11. This estimates the mechanical process of the compression member 5.
In order to suppress the speed variation due to the load torque ripple, correction calculation unit 15 calculates a correction amount of the conduction angle of the switching element (that is, the conduction angle of the 3-phase winding of brushless DC motor 4) based on the mechanical process of the load estimated by process estimation unit 14.
The waveform generating unit 16 synthesizes the conduction angle required for driving the brushless DC motor 4 at the target speed, which is set by the conduction angle control unit 13b of the speed control unit 13, with the conduction angle correction amount set by the correction calculating unit 15, and generates a conduction waveform in which the on-time duty of the switching elements 3a to 3f is 100%. The generated energization waveform is input to the driving unit 17, and the driving unit 17 drives the switching elements 3a to 3f of the inverter 3.
[1-2. actions ]
The operation and action of the motor drive device 20 configured as described above will be described below.
First, the operation of the position detection unit 10 will be described with reference to fig. 1 and 2. Fig. 2 is a timing chart of the motor drive device 20 of the present embodiment. Fig. 2 shows a U-phase terminal voltage waveform Vu, a U-phase induced voltage waveform E generated by the rotation of brushless DC motor 4, drive signals U +, V +, W + of the high-voltage-side switching elements of the respective phases, and the detection timing of the magnetic pole position. In fig. 2, the energization angle to the stator phase winding is 120 degrees. The terminal voltage waveform and the induced voltage waveform of the V-phase and the W-phase are the same waveforms shifted by ± 120 degrees from the terminal voltage waveform and the induced voltage waveform of the U-phase, respectively. When PWM control is performed as speed control for driving brushless DC motor 4 at a predetermined speed, a high-frequency on/off waveform is superimposed on the waveform in fig. 2.
Switching of the stator winding to which power is supplied from the inverter 3 is performed based on the rotational position (magnetic pole position) of the rotor of the brushless DC motor 4. As the rotational position, a zero-crossing point of the induced voltage is detected. In the detection of the zero-cross point, the position detecting unit 10 detects, as the position signal, a point (P1, P2) at which the magnitude relationship between the induced voltage and 1/2 of the inverter input voltage Vdc is inverted, the point occurring in a section where the voltage application to the phase winding is not performed (C1, C2 where both the switching elements 3a, 3d are turned off in the U-phase shown in fig. 2).
Therefore, the position signals are generated 2 times for each phase and 6 times for 3 phases in total at an electrical angle of 1 cycle. The brushless DC motor generates a position signal of a number of times the pole pair (e.g., 3 times or 18 times for a 6-pole motor) every 1 revolution. The conduction angle control unit 13b determines the timing of turning on and off the switching element, starting from the position signal detection timing.
Fig. 3A, 3B, and 3C are timing charts showing the conduction angle of brushless DC motor 4 according to the present embodiment. In these figures, drive signals of the high-side switching elements of the respective phases are shown.
In fig. 3A, the switching elements are turned on and off at the same timing. The conduction angle in this case is 120 degrees. Fig. 3B shows a case where the switching elements are controlled to be turned off later than the on timing of the switching elements, and are driven by applying current at a wide angle wider than 120 degrees. Fig. 3C shows a case where the off timing is controlled earlier than the on timing, and the conduction angle is controlled to be a narrow angle conduction angle smaller than 120 degrees. By independently controlling the on-time and the off-time of the switching element in this manner, the necessary applied torque can be adjusted at the speed and the load state of the brushless DC motor.
Next, speed control of brushless DC motor 4 will be described.
The position detection unit 10 detects a zero cross point of an induced voltage generated by rotation of the rotor of the brushless DC motor 4 having a permanent magnet as a position signal. Therefore, the position signal includes information on the rotation speed of the brushless DC motor 4. Speed detecting unit 11 detects the speed of brushless DC motor 4 based on the interval of the position signal of position detecting unit 10. Specifically, speed detecting unit 11 detects intervals of each position detection, and detects the rotation speed of brushless DC motor 4 from the sum of intervals of position detection (18 times in the case of a 6-pole motor) corresponding to 1 rotation of brushless DC motor 4. And speed control unit 13 controls the driving speed of brushless DC motor 4 by speed feedback control so that the speed difference between the speed of brushless DC motor 4 detected by error detection unit 12 and the target speed disappears.
The speed control unit 13 selects whether or not the PWM control unit 13a or the conduction angle control unit 13b performs speed feedback, based on the motor characteristics and application, the load characteristics, the driving state, and the like.
Further, when driving at an extremely narrow conduction angle, there is a concern that a large increase in motor loss (hysteresis loss) may be caused by an increase in the peak value of the phase current of brushless DC motor 4, thereby causing a decrease in efficiency. Therefore, in the present embodiment, when the PWM duty is less than 50% (the conduction angle is less than 90 degrees), and the speed is very low or the load is low, the conduction angle is 120 degrees, and the PWM control unit 13a is selected. The driving is performed by speed feedback control based on adjustment of the on-time duty ratio by PWM control.
In addition, in a driving state of the load in which the PWM duty becomes 50% or more (conduction angle 90 degrees or more), the driving by the conduction angle control unit 13b is selected. At this time, the on-time duty ratio of the PWM control is fixed to 100%. The speed of brushless DC motor 4 is controlled by feedback control based on increase and decrease of the conduction angle.
By driving the inverter 3 by adjusting the conduction angle with the PWM on-time duty ratio set to 100% as described above, it is possible to reduce the switching loss of the inverter 3, the high-frequency current iron loss of the PWM frequency component, and the high-frequency noise. Therefore, the motor drive device 20 can be reduced in loss and noise. The conduction angle determined by the speed feedback control by the conduction angle control unit 13b is a basic conduction angle of the conduction angle correction control described later.
After the brushless DC motor 4 is started by the PWM control unit 13a, the drive is shifted to the drive by the conduction angle control unit 13 b. At the time of transition, as conduction angle control unit 13b of speed control unit 13 decreases the conduction angle, the PWM control unit 13a increases the on-time duty of PWM by speed feedback for driving brushless DC motor 4 at a predetermined speed. Then, at the time point when the PWM on-time duty ratio reaches 100%, the speed control is switched from the PWM control to the conduction angle control, and the speed control based on the increase and decrease of the conduction angle is performed.
When the load is small and the driving speed of brushless DC motor 4 is higher than the target speed even if the conduction angle reaches 90 degrees, the speed control is switched to the speed control by adjusting the on-time ratio by the PWM control, and the PWM on-time duty ratio is gradually increased until the conduction angle reaches a predetermined conduction angle (120 degrees in the present embodiment).
Next, the correction of the conduction angle will be described. Fig. 4 is a load torque diagram showing load torque in 1 cycle (1 rotation of the brushless DC motor 4) of the compressor 6 of the present embodiment. As shown in fig. 4, the compressor 6 has a step of compressing, discharging, and sucking the refrigerant gas at different load torques in 1 cycle. Therefore, a periodic load torque ripple occurs in 1 rotation of the brushless DC motor 4. This torque ripple causes a periodic speed fluctuation (speed ripple) in 1 rotation of brushless DC motor 4, which causes driving vibration of compressor 6.
Fig. 5 is a diagram showing a position detection interval of the brushless DC motor 4 when the compressor 6 is driven. Fig. 5 shows the interval of position detection by the position detecting unit 10 in 1 cycle of the compressor 6 (1 rotation of the brushless DC motor 4). In the present embodiment, since the 6-pole brushless DC motor is used, the brushless DC motor 4 generates 18 times per 1 rotation and generates a position signal per 20 degrees of rotation angle. As shown in fig. 5, brushless DC motor 4 incorporated in compressor 6 periodically varies the position detection interval during 1 rotation of brushless DC motor 4. That is, it is known that speed pulsation occurs in 1 rotation of the brushless DC motor 4. Fig. 5 shows that the angular velocity is larger as the position detection interval is smaller, and the angular velocity is smaller as the position detection interval is larger. Fig. 5 comparatively shows the position detection intervals in the case where the angular velocity is constant.
It can be confirmed that a certain phase deviation occurs between the rotation angle at which the load torque of the compressor 6 shown in fig. 4 becomes the peak and the rotation angle at which the position detection interval shown in fig. 5 becomes the maximum (that is, the angular velocity becomes the lowest). The phase deviation is caused by the inertia of the rotor and the load connected to the rotor. The process estimation unit 14 estimates the mechanical process of the compressor 6 based on the speed ripple of the brushless DC motor 4 during 1 revolution and the difference between the rotation angle phase of the maximum load torque and the rotation angle phase of the minimum speed. Specifically, in the present embodiment, the point of maximum torque in the compression step can be estimated at a position that is advanced by 120 degrees from the rotational angle at which the angular velocity of brushless DC motor 4 is the lowest.
Fig. 6 shows a phase of a torque correction pattern (pattern) created based on the load torque characteristics of the compressor 6 shown in fig. 4.
The correction calculation unit 15 calculates an energization angle correction amount during energization to the motor winding of the brushless DC motor 4, after matching a torque correction pattern phase shown in fig. 6 prepared in advance with the mechanical process phase of the compressor 6 estimated by the process estimation unit 14. In the present embodiment, the conduction angle correction amount is calculated by multiplying the torque correction rate at each rotation angle of the torque correction pattern of fig. 6 by the deviation between the actual position detection interval at each rotation angle and the position detection interval at a constant speed.
Therefore, the energization angle correction amount is applied more under the driving condition where the speed pulsation of the compressor 6 becomes large as in the low speed or the high load, and is applied less under the driving condition where the speed pulsation becomes small as in the high speed or the low load. Therefore, an appropriate correction amount is obtained according to the load state and the driving speed of the compressor 6.
Fig. 7 is a diagram showing the conduction angle of the brushless DC motor 4 in the present embodiment. The conduction angle shown in fig. 7 is generated by combining the conduction angle correction amount set by the correction calculation unit 15 and the basic conduction angle set by the conduction angle control unit 13b of the speed control unit 13 based on the speed feedback control by the waveform generation unit 16. As described above, the current conduction angle is adjusted and corrected so as to suppress the load torque ripple at each rotation angle with respect to the basic current conduction angle determined by the speed feedback control of brushless DC motor 4. The inverter 3 is driven by the driving unit 17.
The drive waveform of the brushless DC motor 4 generated in this manner expands the conduction angle in the compression step in which the load torque is large, and increases the applied torque. The increase in the applied torque in the compression step reduces the difference between the applied torque and the load torque. Therefore, the acceleration of the brushless DC motor 4 generated by the torque difference between the applied torque and the load torque is reduced. As a result, the speed of brushless DC motor 4 can be suppressed from decreasing in the compression step.
Further, by suppressing the speed reduction of brushless DC motor 4 in the compression step, the speed of brushless DC motor 4 at 1 revolution is increased. Therefore, the basic conduction angle set by the speed feedback control performed by the speed control unit 13 decreases. That is, in the suction step in which the applied torque becomes larger than the load torque and the brushless DC motor 4 is accelerated to become faster than the target speed, the applied torque is reduced. Therefore, the speed increase can be suppressed.
Fig. 8 is a diagram showing the speed ripple of the brushless DC motor 4 according to the present embodiment. As shown in fig. 8, with the configuration of the present embodiment, it can be confirmed that the width of change in the position detection interval at the rotation angle of brushless DC motor 4 is reduced. That is, by correcting and optimizing the conduction angle based on the torque ripple of the compressor 6, the brushless DC motor 4 can suppress the speed decrease in the compression step and the speed increase in the suction step. Therefore, the speed ripple in 1 revolution of the brushless DC motor 4 can be suppressed.
The speed pulsation of the compressor 6 (i.e., the increase and decrease in the speed of the brushless DC motor 4 during 1 revolution) is a factor of the occurrence of vibration of the compressor 6. Here, the motor drive device 20 of the present invention can reduce load drive vibration having periodic torque pulsation, such as the compressor 6. In the experiments of the inventors, when the compressor 6 is driven by the motor driving device 20 of the present invention, it was actually confirmed that the driving vibration of the compressor 6 can be suppressed by 50% or more at most as compared with the conventional art.
The driving vibration causes driving noise due to resonance of the peripheral portion. Therefore, the suppression of the driving vibration by the configuration of the present invention can also reduce the noise of the motor driving device 20.
In the present embodiment, speed control for driving the brushless DC motor 4 at a predetermined speed and speed ripple suppression control for driving a load having torque ripple during 1 rotation of the compressor or the like are performed only by adjusting the conduction angle. Therefore, the drive control of brushless DC motor 4 can be simplified, and the cost of the control device constituting control unit 21 can be reduced.
The present embodiment further includes a PWM control unit 13a that turns on and off the switching elements 3a to 3f of the inverter 3 at a high frequency and at an arbitrary duty ratio in order to adjust the inverter output voltage. When the driving speed of brushless DC motor 4 is adjusted by adjusting the conduction angle of inverter 3, the on-time duty of PWM control is set to 100%.
This can significantly reduce the switching loss of the switching elements 3a to 3f associated with the PWM control and the motor iron loss caused by the high-frequency current of the PWM frequency component, and thus can provide a high-efficiency motor driving device. Further, since the reduction in the number of switching times of the switching elements 3a to 3f suppresses the generation of electromagnetic noise, it is possible to reduce the cost of the device resulting from simplification of the filter circuit. Further, noise reduction of the device can be achieved due to reduction of noise in a high frequency band accompanying high frequency switching.
[1-3. Effect, etc. ]
As described above, motor drive device 20 of the present embodiment includes brushless DC motor 4 and inverter 3 that supplies power to brushless DC motor 4. Further, a conduction angle control unit 13b is provided, which adjusts the conduction angle of the electric power supplied to brushless DC motor 4. The brushless DC motor 4 drives a load having a periodic pulsating torque. The motor drive device 20 is configured to change an energization angle from the inverter 3 to the brushless DC motor 4 in accordance with the pulsation of the load torque.
Thereby, inverter 3 supplies electric power to brushless DC motor 4 at a conduction angle set by conduction angle control unit 13b based on the pulsation of the load torque. Therefore, vibration during driving of the load having torque ripple can be suppressed without performing PWM control. In addition, the motor drive device 20 can be made more efficient.
In the present embodiment, the inverter 3 includes a PWM control unit 13a that turns on and off the switching elements 3a to 3f of the inverter 3 at a high frequency and with an arbitrary duty ratio in order to adjust the inverter output voltage. When the driving speed of brushless DC motor 4 is controlled by adjusting the conduction angle of inverter 3, the on-time duty of the switching elements of inverter 3 by PWM control unit 13a is set to 100%.
This can reduce switching loss of the switching elements 3a to 3f associated with PWM control and motor iron loss due to suppression of high-frequency current of PWM frequency components, and thus can provide a high-efficiency motor driving device.
Further, since the generation of electromagnetic noise can be suppressed by reducing the number of switching times of the switching elements 3a to 3f, it is possible to reduce the cost of the device due to simplification of the filter circuit. Further, high-frequency band noise caused by high-frequency switching can be reduced by reducing the number of times of switching of the switching elements 3a to 3f, and thus noise reduction of the device can be achieved.
The motor driving device 20 shown in the present embodiment is used for driving the brushless DC motor 4 that drives the compressor 6 constituting the refrigeration cycle. This can improve the COP (Coefficient Of Performance) Of the compressor 6, and reduce vibration and noise.
The above-described embodiments are examples for illustrating the technique of the present invention. Therefore, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or equivalents thereto.
(embodiment mode 2)
[2-1. Structure ]
Fig. 9 is a block diagram of refrigerator 18 using motor drive device 20 shown in embodiment 1. The refrigerator 18 is an example of a refrigeration cycle apparatus.
The refrigerator 18 has a refrigeration cycle including the compressor 6, the condenser 7, the decompressor 8, and the evaporator 9. The evaporator 9 is used for cooling a food storage compartment 19 surrounded by a heat insulating material (not shown).
[2-2. actions ]
Next, the operation of refrigerator 18 will be described.
In recent years, with the improvement of heat insulation technology such as the use of vacuum heat insulation materials, the intrusion of heat from the outside is extremely reduced. Therefore, the interior of the refrigerator is in a stable cooling state in most of the day except for the morning and evening housekeeping time periods in which the opening and closing of the door is frequently performed. At this time, the compressor 6 is driven at a low speed and a low load with a reduced cooling capacity.
Therefore, it is very important to reduce the power consumption of the refrigerator to improve the driving efficiency of the compressor 6, that is, the brushless DC motor 4 at low speed and low output. Therefore, in the refrigerator 18 of the present embodiment, when the driving speed of the compressor 6 is a relatively low speed (for example, 35Hz or less), the relay 2c of the rectifying/smoothing circuit 2 shown in fig. 1 is turned OFF (OFF) and the full-wave rectified voltage of the ac power supply 1 is input to the inverter 3. This can reduce switching loss of the inverter circuit. Further, the conduction angle is increased by using full-wave rectification as the inverter input voltage, and even when the compressor 6 is driven at a low speed and a low load, the driving by the conduction angle control can be performed.
In general, since a refrigerator is installed indoors and is always energized, quietness and energy saving are required. Therefore, it is very effective to apply the present invention to a refrigerator as a refrigeration cycle apparatus using the motor drive device 20 of the present invention which can realize high efficiency, low vibration, and low noise.
In addition, regarding energy saving performance of the refrigerator, it is very effective to drive the compressor at a low speed at the time of low load to reduce the cooling capacity and improve the system efficiency of the refrigeration cycle. However, since the driving vibration increases when the speed of the compressor is lowered, the lower limit speed that can be practically used is limited. However, by using the refrigeration cycle using the motor drive device 20 of the present invention for the refrigerator 18, the lower limit speed that can be actually used can be reduced by suppressing the driving vibration of the compressor 6. Therefore, the system efficiency of the refrigeration cycle can be improved, and further energy saving performance of the refrigerator 18 can be improved.
[2-3. Effect, etc. ]
As described above, in the present embodiment, by using the motor drive device 20 of embodiment 1, the refrigerator 18 can suppress the drive vibration of the compressor 6, and can reduce the lower limit speed that can be actually used. Therefore, the system efficiency of the refrigeration cycle can be improved, and the energy saving performance can be improved. That is, it is possible to provide a refrigerator with low power consumption due to a high COP refrigeration cycle, and it is possible to achieve noise suppression due to driving vibration of a compressor and noise reduction due to suppression of broadband noise caused by not using PWM control.
In the present embodiment, the refrigerator 18 is exemplified as an example of the refrigeration cycle apparatus, but the refrigeration cycle apparatus is not limited thereto.
The present invention can be applied to a motor drive device in which drive vibration is generated by torque pulsation at the time of load driving. Specifically, the present invention is applicable to various refrigeration cycle devices such as showcases, including refrigerators using compressors.
Claims (8)
1. A motor drive device characterized by comprising:
a brushless DC motor that drives a load having a periodic pulsating torque;
an inverter for supplying electric power to the brushless DC motor; and
a control unit for controlling the inverter, wherein the inverter is connected to the inverter,
the control unit is configured to adjust a conduction angle of the brushless DC motor in power supply from the inverter to the brushless DC motor in accordance with pulsation of the load.
2. The motor drive device according to claim 1, wherein:
the control unit is configured to control a driving speed of the brushless DC motor by adjusting an energization angle of the brushless DC motor.
3. The motor drive device according to claim 2, wherein:
the control unit is configured to perform PWM control for turning on and off switching elements of the inverter at a high frequency at an arbitrary time ratio,
when the driving speed of the brushless DC motor is controlled by adjusting the conduction angle of the brushless DC motor, the on-time ratio of the switching elements of the inverter in the PWM control is set to 100%.
4. The motor drive device according to claim 1, wherein:
the control unit includes an energization angle control unit that controls an energization angle of the brushless DC motor.
5. A motor drive device according to claim 3, wherein:
the control unit has a PWM control unit that generates a signal for the PWM control.
6. The motor drive device according to any one of claims 1 to 5, wherein:
the load driven by the brushless DC motor is a compressor constituting a refrigeration cycle.
7. A refrigeration cycle apparatus, characterized in that:
a compressor driven by the motor driving device according to any one of claims 1 to 6.
8. A refrigerator characterized in that:
a compressor driven by the motor driving device according to any one of claims 1 to 6.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2019133457A JP2021019416A (en) | 2019-07-19 | 2019-07-19 | Motor drive device, refrigerator using the same, and refrigeration cycle device |
| JP2019-133457 | 2019-07-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112242801A true CN112242801A (en) | 2021-01-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010679197.1A Pending CN112242801A (en) | 2019-07-19 | 2020-07-15 | Motor drive device, and refrigerator and refrigeration cycle device using same |
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| JP (1) | JP2021019416A (en) |
| CN (1) | CN112242801A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040267421A1 (en) * | 2002-04-30 | 2004-12-30 | International Rectifier Corp. | Electronically controlled power steering system for vehicle and method and system for motor control |
| JP2007330011A (en) * | 2006-06-07 | 2007-12-20 | Matsushita Electric Ind Co Ltd | Drive method and drive unit for brushless dc motor |
| CN109155601A (en) * | 2016-06-03 | 2019-01-04 | 松下知识产权经营株式会社 | Motor driver and electric equipment with the compressor for using the motor driver |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002247873A (en) * | 2001-02-16 | 2002-08-30 | Fujitsu General Ltd | Electric motor controlling method |
| JP4352860B2 (en) * | 2003-11-07 | 2009-10-28 | トヨタ自動車株式会社 | Electric motor control device |
-
2019
- 2019-07-19 JP JP2019133457A patent/JP2021019416A/en active Pending
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2020
- 2020-07-15 CN CN202010679197.1A patent/CN112242801A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040267421A1 (en) * | 2002-04-30 | 2004-12-30 | International Rectifier Corp. | Electronically controlled power steering system for vehicle and method and system for motor control |
| JP2007330011A (en) * | 2006-06-07 | 2007-12-20 | Matsushita Electric Ind Co Ltd | Drive method and drive unit for brushless dc motor |
| CN109155601A (en) * | 2016-06-03 | 2019-01-04 | 松下知识产权经营株式会社 | Motor driver and electric equipment with the compressor for using the motor driver |
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| JP2021019416A (en) | 2021-02-15 |
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