Dryer and control method

Abstract

To provide a drying machine in which a compressor can be stably activated even when large load is applied to the compressor.SOLUTION: A drying machine of an embodiment of the present invention comprises: a compressor comprising a rotoring piston, a compressor motor for rotating the rotoring piston; and a control portion performing first control increasing number of revolution of the compressor motor with a first acceleration at start-up of the compressor, and performs second control increasing the number of revolution to the second number of revolution with second acceleration when the number of revolution reaches the first prescribed number of revolution. The second acceleration is greater than the first acceleration, and the second number of revolution is greater than the first number of revolution.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a dryer and a control method.

Background Art

[0002] Among dryers, there are those that use a compressor, such as a heat pump system. In a compressor, at high temperatures, the load increases, resulting in large fluctuations in the load during compression and suction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a dryer that can stably start a compressor even when the load on the compressor increases.

Means for Solving the Problems

[0005] The dryer according to the embodiment is A compressor having a single-rotating piston and a compressor motor that rotates the single-rotating piston; a control unit that performs a first control to increase the rotational speed of the compressor motor with a first acceleration when the compressor is started, and when the rotational speed reaches a predetermined first rotational speed, performs a second control to increase the rotational speed to a predetermined second rotational speed higher than the first rotational speed with a second acceleration greater than the first acceleration, wherein the control unit performs the first control to increase the rotational speed with a first acceleration based on the d-axis current flowing through the compressor motor, and performs the second control to increase the rotational speed with a second acceleration based on the q-axis current flowing through the compressor motor, with the rotation due to the first acceleration being performed by forced commutation and the rotation due to the second acceleration being performed by speed control. .

Brief Description of the Drawings

[0006] [Figure 1] A diagram showing an example of the configuration of the dryer according to the embodiment. [Figure 2] A diagram showing an example of the drive control system of each motor in the dryer according to the embodiment. [Figure 3] A diagram showing an example of the processing flow of the dryer according to the embodiment. [Figure 4] A diagram showing an example of the relationship between the time and the rotational frequency of the compressor motor when the control circuit according to the embodiment controls the rotational speed of the compressor motor. [Figure 5] This figure shows an example of the winding current (for one phase) waveform when the control circuit of the embodiment controls the rotational speed of the compressor motor and generates d-axis current and q-axis current in the compressor motor. [Figure 6] This figure shows an example of the relationship between time and the rotational frequency of the compressor motor when the control being compared is performed. [Figure 7] A diagram showing an example of a compressor 27 in an embodiment. [Modes for carrying out the invention]

[0007] The dryer of the embodiment will be described below with reference to the drawings. In the following description, components having the same or similar function will be denoted by the same reference numeral. Duplication of these components may be omitted. "Based on XX" means "based on at least XX," and may also include cases based on other elements in addition to XX. "Based on XX" is not limited to cases where XX is used directly, but may also include cases where calculations or processing have been performed on XX. "XX or YY" is not limited to cases where either XX or YY is used, but may also include cases where both XX and YY are used. This is also true when there are three or more selective elements. "XX" and "YY" are arbitrary elements (e.g., arbitrary information). Furthermore, "detection" is not limited to cases where the physical quantity of the object is directly sensed, but may also include cases where other physical quantities related to the physical quantity of the object are directly or indirectly acquired, and the physical quantity of the object is estimated or identified from the acquired other physical quantities. Furthermore, "acquisition" is not limited to cases where the object (including information) itself is directly received, but may also include cases where the directly received object (including information) becomes the object through calculations or processing.

[0008] Several embodiments are described below. The dryer in the embodiment is a heat pump type dryer using a compressor having a rotary piston. Examples of compressors having a rotary piston include single rotary compressors, twin rotary compressors, triple rotary compressors, and the like.

[0009] <Embodiment> (Overall configuration of the dryer) The dryer 100 of the embodiment will be described with reference to Figures 1 to 7. In this embodiment, a drum-type washer-dryer will be used as an example of the dryer 100. Figure 1 is a diagram showing an example of the configuration of the dryer 100 of the embodiment. The outer casing 1 is hollow and has a front plate, a rear plate, a left plate, a right plate, a bottom plate, and a top plate. A through-hole-shaped entrance / exit 2 is formed in the front plate of the outer casing 1. A door 3 is attached to the front plate of the outer casing 1. This door 3 can be operated by the user from the front between a closed state and an open state. When the door 3 is closed, the entrance / exit 2 is closed, and when the door 3 is open, the entrance / exit 2 is open. A water receiving tank 4 is fixed inside the outer casing 1. This water receiving tank 4 is cylindrical with a closed rear surface and is arranged in an inclined state with its axis CL sloping downward from front to rear. The front of this water receiving tank 4 is open, and when the door 3 is closed, the door 3 airtightly closes the front of the water receiving tank 4.

[0010] A drum motor 5 is fixed to the rear plate of the water receiving tank 4, located outside the water receiving tank 4. This drum motor 5 is a speed-controllable DC brushless motor, and its rotating shaft 6 protrudes into the water receiving tank 4. This rotating shaft 6 is positioned in conjunction with the axis CL of the water receiving tank 4, and a drum 7 is fixed to the rotating shaft 6, located inside the water receiving tank 4. This drum 7 is cylindrical with a closed rear surface and rotates integrally with the rotating shaft 6 when the drum motor 5 is operating. The front of this drum 7 faces the entrance / exit 2 from the rear via the front of the water receiving tank 4, and laundry is loaded and unloaded into the drum 7 from the front through the entrance / exit 2, the front of the water receiving tank 4, and the front of the drum 7 when the door 3 is open.

[0011] The drum 7 has multiple through holes 8, and the internal space of the drum 7 is connected to the internal space of the water receiving tank 4 through each of the multiple through holes 8. Multiple baffles 9 are fixed to the drum 7. Each of these baffles 9 moves in the circumferential direction around the axis line CL as the drum 7 rotates, and the laundry inside the drum 7 is agitated as it moves in the circumferential direction while getting caught on each of the baffles 9 before falling due to gravity.

[0012] A water supply valve 10 is fixed inside the outer casing 1. This water supply valve 10 has an inlet and an outlet, and the inlet of the water supply valve 10 is connected to a water tap. This water supply valve 10 is driven by a water supply valve motor 11 (see Figure 1), and the outlet of the water supply valve 10 is switched between an open state and a closed state depending on the rotation amount of the water supply valve motor 11. The outlet of this water supply valve 10 is connected to a water filling case 12. When the water supply valve 10 is open, tap water is injected into the water filling case 12 through the water supply valve 10, and when the water supply valve 10 is closed, tap water is not injected into the water filling case 12. This water filling case 12 is fixed inside the outer casing 1 at a higher position than the water receiving tank 4 and has a cylindrical water inlet 13. This water inlet 13 is inserted into the water receiving tank 4, and the tap water injected into the water filling case 12 from the water supply valve 10 is injected into the water receiving tank 4 from the water inlet 13.

[0013] The upper end of the drain pipe 14 is connected to the water receiving tank 4 at its lowest point, and a drain valve 15 is interposed in the drain pipe 14. This drain valve 15 is driven by a drain valve motor 16 (see Figure 1) and switches between an open state and a closed state depending on the rotation amount of the drain valve motor 16. When the drain valve 15 is closed, tap water injected into the water receiving tank 4 from the water inlet 13 is stored in the water receiving tank 4, and when the drain valve 15 is open, the tap water in the water receiving tank 4 is discharged to the outside of the water receiving tank 4 through the drain pipe 14.

[0014] A main duct 17 is fixed to the bottom plate of the outer casing 1, located below the water receiving tank 4. This main duct 17 is cylindrical and oriented in the front-to-back direction, and the lower end of a front duct 18 is connected to the front end of the main duct 17. This front duct 18 is cylindrical and oriented in the up-to-down direction, and the upper end of the front duct 18 is connected to the internal space of the water receiving tank 4 at the front end of the water receiving tank 4. A fan casing 19 is fixed to the rear end of the main duct 17. This fan casing 19 has a through-hole-shaped intake port 20 and a cylindrical exhaust port 21, and the internal space of the fan casing 19 is connected to the internal space of the main duct 17 via the intake port 20.

[0015] A fan motor 22 is fixed to the fan casing 19, located outside the fan casing 19. This fan motor 22 has a rotating shaft 23 that protrudes into the inside of the fan casing 19, and a fan 24 is fixed to the rotating shaft 23, located inside the fan casing 19. This fan 24 is a centrifugal type that draws in air axially and discharges it radially. The intake port 20 of the fan casing 19 faces the fan 24 in the axial direction of the fan 24, and the exhaust port 21 of the fan casing 19 faces the fan 24 in the radial direction of the fan 24.

[0016] The lower end of the rear duct 25 is connected to the exhaust port 21 of the fan casing 19. This rear duct 25 is cylindrical and oriented vertically, and its upper end is connected to the internal space of the water receiving tank 4 at the rear end of the water receiving tank 4. These rear duct 25, fan casing 19, main duct 17, front duct 18, and water receiving tank 4 constitute an annular circulation duct 26 with the internal space of the water receiving tank 4 as its starting and ending points. When the fan motor 22 is operating with the door 3 closed, the fan 24 rotates in a constant direction, causing air in the water receiving tank 4 to be drawn from the front duct 18 through the main duct 17 into the fan casing 19, and then returned from the fan casing 19 through the rear duct 25 into the water receiving tank 4.

[0017] Inside the outer box 1, a compressor 27 is fixed. This compressor 27 is arranged outside the circulation duct 26 and has a discharge port for discharging refrigerant and a suction port for sucking refrigerant. This compressor 27 uses a compressor motor 28 (see FIG. 2 described later) as a drive source, and the compressor motor 28 is composed of a DC brushless motor whose speed can be controlled.

[0018] Inside the main duct 17, a condenser 29 is fixed. This condenser 29 heats air and is composed of fixing each of a plurality of plate-shaped heating fins 31 in a contact state on the outer peripheral surface of a single refrigerant pipe 30 that meanders in a serpentine shape. The refrigerant pipe 30 of this condenser 29 is connected to the discharge port of the compressor 27, and in the operating state of the compressor motor 28, the refrigerant discharged from the discharge port of the compressor 27 enters the refrigerant pipe 30 of the condenser 29.

[0019] FIG. 2 is a diagram showing an example of a drive control system for each motor in the dryer 1 hundred of the embodiment. Each motor shown in FIG. 2 is a drum motor 5, a fan motor 22, and a compressor motor 28. The inverter circuit 34 is configured by connecting six IGBTs (Insulated Gate Bipolar Transistors) 35a to 35f (switching elements) in a three-phase bridge connection, and flywheel diodes 36a to 36f are connected between the collector and emitter of each of the IGBTs 35a to 35f. Each phase output terminal of the inverter circuit 34 is connected to each phase winding of the drum motor 5. The inverter circuit 34 is an example of a drive circuit for driving the compressor motor 28.

[0020] The emitters of the IGBTs 35d, 35e, 35f on the lower arm side are connected to the ground via shunt resistors 37u, 37v, 37w. Also, the common connection point between the emitters of the IGBTs 35d, 35e, 35f and the shunt resistors 37u, 37v, 37w is connected to the input terminal of the control circuit 42A (microprocessor, microcomputer).

[0021] Internally, the control circuit 42A, although not shown in the diagram, is composed of an operational amplifier and other components, and a level shift circuit amplifies the terminal voltage of the shunt resistor 37u~37w, while also applying a bias (for example, 0 to +3.3V) so that the output range of the amplified signal falls within the positive side.

[0022] A similarly configured inverter circuit 38 and shunt resistors 39 (u, v, w) are provided for the fan motor 22, and an inverter circuit 40 and shunt resistors 41 (u, v, w) are provided for the compressor motor 28. The inverter circuits 38 and 40 are controlled by another control circuit 42B (an example of a microprocessor, microcomputer, or control unit), and the control circuits 42A and 42B are capable of bidirectional communication via serial communication.

[0023] A drive power supply circuit 43 is connected to the input side of inverter circuits 34, 38, and 40. The drive power supply circuit 43 is connected to a 100V AC power supply via a reactor 44 (inductive reactor) at one end and comprises a full-wave rectifier circuit 45 composed of a diode bridge, and two capacitors 46a and 46b connected in series to the output side of the full-wave rectifier circuit 45. The common connection point of capacitors 46a and 46b is connected to one of the input terminals of the full-wave rectifier circuit 45. Note that if the boost operation using the reactor 44 is not performed, the drive power supply circuit 43 may double the voltage of the 100V AC power supply and supply a DC voltage of approximately 280V to the inverter circuit 34, etc.

[0024] Another full-wave rectifier circuit 47, similarly composed of a diode bridge, is connected in parallel to the input terminal of the full-wave rectifier circuit 45, and an IGBT 48 is connected between the output terminals of the full-wave rectifier circuit 47. The on / off control of the IGBT 48 is performed by the control circuit 42B.

[0025] A series circuit of resistors 49a and 49b, and a series circuit of resistors 50a and 50b are connected between the input terminals of inverter circuits 34 and 38, respectively. The common connection points of these circuits are connected to the input terminals of control circuits 42A and 42B. Control circuits 42A and 42B detect the drive power supply voltage input to inverter circuits 34 and 38 by referring to the voltage at each of the common connection points.

[0026] Furthermore, a position sensor 51 (u, v, w), which is composed of, for example, a Hall IC, is placed on the drum motor 5 to detect the position of the rotor piston 27a, which will be described later. The sensor signal output by the position sensor 51 is supplied to the control circuit 42A. In addition, a current sensor 52, which is composed of, for example, a current transformer (CT), is interposed between the AC power supply and the reactor 44, and the sensor signal output by the current sensor 52 is supplied to the control circuit 42B.

[0027] Control circuit 42A detects the current flowing through each phase winding of the drum motor 5 using shunt resistors 37u, 37v, and 37w. Control circuit 42B also detects the current flowing through each phase winding of the fan motor 22 and compressor motor 28 using shunt resistors 39 and 41. Based on the detected current values, control circuits 41A and 42B estimate the phase θ and rotational angular velocity ω of the secondary rotating magnetic field, and obtain the excitation current component Id (i.e., d-axis current) and torque current component Iq (i.e., q-axis current), which are two-phase power currents, by performing orthogonal coordinate transformation (αβ transformation) and dq (direct-quadrature) coordinate transformation on the three-phase currents. When a speed command is given from an external source, control circuits 42A and 42B generate current commands Idref and Iqref based on the estimated phase θ and rotational angular velocity ω and current components Id and Iq, and then convert these into voltage commands Vd and Vq, performing orthogonal coordinate transformation and three-phase coordinate transformation. Ultimately, the drive signal is generated as a PWM (Pulse Width Modulation) signal and output to the respective phase windings of the drum motor 5, fan motor 22, and compressor motor 28 via inverter circuits 34, 38, and 40.

[0028] In the above configuration, the inverter circuits 34, 38, and 40, the control circuits 42A and 42B, the drive power supply circuit 43, the reactor 44, the full-wave rectifier circuit 47, and the IGBT 48 constitute the drive unit 60.

[0029] Next, the details of the control of the compressor motor 28 by the control circuit 42B of the embodiment will be described. Figure 3 is a diagram showing an example of the processing flow of the dryer 100 of the embodiment. Here, the details of the control of the compressor motor 28 by the control circuit 42B when the compressor 27 is started will be explained with reference to Figure 3.

[0030] When the compressor 27 is started, the control circuit 42B controls the compressor motor 28 to increase its rotational speed at a predetermined acceleration (for example, 0.8 Hz / second, an example of a first acceleration) by forced commutation using the d-axis current while the compressor is not rotating (step S1). Specifically, the control circuit 42B generates a PWM signal to increase the rotational speed of the compressor motor 28 at a predetermined acceleration (an example of a first acceleration) by forced commutation using the d-axis current while the compressor is not rotating. The control circuit 42B then outputs the generated PWM signal to the inverter circuit 40. The inverter circuit 40 flows the d-axis current to the compressor motor 28 in accordance with the PWM signal generated by the control circuit 42B, and increases the rotational speed of the compressor motor 28 at a predetermined acceleration (an example of a first acceleration) by forced commutation.

[0031] The control circuit 42B determines whether or not the rotational speed has reached a predetermined speed (for example, 12Hz, an example of the first rotational speed) (step S2). For example, the control circuit 42B determines that the rotational speed has not reached the predetermined speed if "predetermined rotational speed / predetermined acceleration (in the above example, 12Hz / (0.8Hz / sec) = 15 seconds)" has not elapsed since the start of control. Also, the control circuit 42B determines that the rotational speed has reached the predetermined speed if "predetermined rotational speed / predetermined acceleration (in the above example, 12Hz / (0.8Hz / sec) = 15 seconds)" has elapsed since the start of control by forced commutation.

[0032] If the control circuit 42B determines that the motor is not at a predetermined rotational speed (NO in step S2), it returns to the process of step S2. If the control circuit 42B determines that the motor is at a predetermined rotational speed (YES in step S2), it controls the compressor motor 28 to increase its rotational speed at an acceleration greater than a predetermined acceleration (an example of a second acceleration) (step S3) by speed control (also called frequency control) using the q-axis current. Specifically, if the control circuit 42B determines that the motor is at a predetermined rotational speed (an example of a first rotational speed), it generates a PWM signal to change the compressor motor 28 from its predetermined rotational speed (an example of a first rotational speed) to a predetermined rotational speed higher than that predetermined rotational speed (for example, 22Hz, an example of a second rotational speed) by speed control using the q-axis current. The control circuit 42B then outputs the generated PWM signal to the inverter circuit 40. The inverter circuit 40 supplies a q-axis current to the compressor motor 28 in response to the PWM signal generated by the control circuit 42B, and increases the speed of the compressor motor 28 to a predetermined rotational speed (an example of a second rotational speed) through speed control.

[0033] Furthermore, the PWM signal generated by the control circuit 42B changes the rotation speed from a predetermined rotation speed (an example of the first rotation speed) to a predetermined rotation speed higher than that predetermined rotation speed (an example of the second rotation speed). Therefore, an acceleration greater than a predetermined acceleration (an example of the first acceleration) (an example of the second acceleration) becomes an infinite acceleration. However, physically, as will be explained later, this does not result in infinite acceleration.

[0034] When the rotational speed of the compressor motor 28 increases to a predetermined rotational speed (an example of a second rotational speed) due to speed control, the control circuit 42B changes the acceleration (an example of a second acceleration) to a predetermined acceleration (an example of a first acceleration) in the speed control (step S4). For example, after switching from forced commutation to speed control, if the time required to increase to a predetermined rotational speed (an example of a second rotational speed) determined in advance through experiments or other means has elapsed, the control circuit 42B changes the acceleration (an example of a second acceleration) to a predetermined acceleration (an example of a first acceleration) in the speed control. By increasing the rotational speed from a predetermined rotational speed (an example of a first rotational speed) to a predetermined rotational speed (an example of a second rotational speed) with this acceleration (an example of a second acceleration), the torque deficiency is compensated for, and the compressor motor 28 is prevented from losing synchronism.

[0035] The control circuit 42B determines whether the rotational speed has reached the final target speed (i.e., the final target rotational speed, an example of the third rotational speed) (step S5). For example, the control circuit 42B determines that the rotational speed has not reached the final target speed (i.e., the final target rotational speed) if "(final target rotational speed - predetermined rotational speed (an example of the second rotational speed)) / predetermined acceleration (an example of the first acceleration)" has elapsed since reaching a predetermined rotational speed (an example of the second rotational speed). Also, the control circuit 42B determines that the rotational speed has reached the final target speed (i.e., the final target rotational speed) if "(final target rotational speed - predetermined rotational speed (an example of the second rotational speed)) / predetermined acceleration (an example of the first acceleration)" has elapsed since reaching a predetermined rotational speed (an example of the second rotational speed).

[0036] If the control circuit 42B determines that the rotational speed is not the final target speed (i.e., the final target rotational speed) (NO in step S5), it returns to the process of step S5. If the control circuit 42B determines that the rotational speed has reached the final target speed (i.e., the final target rotational speed) (YES in step S5), it maintains that final target speed by performing PI (Proportional-Integral) control (step S6).

[0037] As explained above, the control circuit 42B changes the acceleration according to the rotational speed and controls the rotational speed of the compressor motor 28 by switching from forced commutation to speed control. Here, we will explain the relationship between time and the rotational frequency of the compressor motor 28 when the control circuit 42B performs the above control, and the waveforms of the d-axis current and q-axis current flowing through the compressor motor 28.

[0038] Figure 4 shows an example of the relationship between time and the rotational frequency of the compressor motor 28 when the control circuit 42B of the embodiment controls the rotational speed of the compressor motor 28. Figure 5 shows an example of the waveform of the winding current (for one phase) when d-axis current and q-axis current are generated in the compressor motor 28 when the control circuit 42B of the embodiment controls the rotational speed of the compressor motor 28. Part (a) of Figure 5 shows the overall waveform of the current flowing through the compressor motor 28. Part (b) of Figure 5 shows an enlarged waveform of the current flowing through the compressor motor 28 during a period that includes the period before and after the control switches from forced commutation to speed control.

[0039] When the control circuit 42B performs the processing flow shown in Figure 3, the rotational speed of the compressor motor 28 increases at a predetermined acceleration (an example of the first acceleration) due to forced commutation by the d-axis current during the period from the start of the compressor 27 to reaching a predetermined rotational speed (for example, 12 Hz, an example of the first rotational speed), as shown in Figure 4. In this case, as can be seen from part 5(a) of Figure 5, the frequency of the waveform of the d-axis current gradually increases during the period from the start to reaching a predetermined rotational speed (for example, 12 Hz, an example of the first rotational speed). That is, the rotational speed of the compressor motor 28 is gradually increasing. Also, since the d-axis current is a current that does not contribute to torque, as can be seen from part 5(a) of Figure 5, the amplitude of the d-axis current is larger than the amplitude of the q-axis current which contributes to torque used in speed control. By increasing the amplitude of the d-axis current in this way, the force generated in the rotational direction of the compressor motor 28 is increased, causing the rotor piston 27a to rotate.

[0040] Furthermore, as mentioned above, even if an acceleration greater than a predetermined acceleration (an example of a first acceleration) in speed control (an example of a second acceleration) is considered to be infinite acceleration, physically, as shown in part (b) of Figure 5, it does not become infinite acceleration. Specifically, due to the control by the control circuit 42B with a rapid change in acceleration, the rotational speed of the compressor motor 28 changes from a predetermined rotational speed (e.g., 12 Hz) with a finite acceleration that the compressor motor 28 can respond to, and then gradually increases toward a rotational speed higher than the predetermined rotational speed (e.g., 22 Hz). However, due to this rapid change in control, physically, the rotational speed temporarily exceeds a rotational speed higher than the predetermined rotational speed (e.g., 12 Hz) (e.g., 22 Hz), then decreases, and then stabilizes at a rotational speed higher than the predetermined rotational speed (e.g., 12 Hz) (e.g., 22 Hz). Since the q-axis current is a current that contributes to torque, the amplitude of the q-axis current flowing through the compressor motor 28 while speed control is being performed is smaller than the amplitude of the d-axis current flowing through the compressor motor 28 during forced commutation.

[0041] Then, in speed control, once the rotational speed stabilizes at a rotational speed higher than a predetermined rotational speed (e.g., 22Hz) (e.g., 12Hz), the system switches from a predetermined acceleration (an example of a second acceleration) to a predetermined acceleration (an example of a first acceleration), and the rotational speed of the compressor motor 28 increases at a constant rate over time to the final target rotational speed, as shown in Figure 4. Finally, the rotational speed of the compressor motor 28 is kept constant at the final target rotational speed by PI control by the control circuit 42B.

[0042] (advantage) The dryer 100 of the embodiment has been described above. The dryer 100 comprises a compressor 27 and a control circuit 42B (an example of a control unit). The compressor 27 has a rotating piston 27a and a compressor motor 28 that rotates the rotating piston 27a. The control circuit 42B performs forced commutation control (an example of first control) to increase the rotational speed of the compressor motor 28 with a first acceleration (e.g., 0.8 Hz / sec) when the compressor 27 is started, and when the rotational speed reaches a predetermined first rotational speed (e.g., 12 Hz), it performs speed control (an example of second control) to increase the rotational speed to a predetermined second rotational speed (e.g., 22 Hz) higher than the first rotational speed with a second acceleration greater than the first acceleration. In this way, the dryer 100 can stably start the compressor even when the load on the compressor is large.

[0043] Here, we will explain the relationship between time and the rotation frequency of the compressor motor 28 when the control under comparison is performed. Figure 6 shows an example of the relationship between time and the rotation frequency of the compressor motor 28 when the control under comparison is performed. The control under comparison is a control that increases the rotation of the compressor motor 28 from a non-rotating state to the final target speed (i.e., the final target rotational speed) at a predetermined acceleration (e.g., 0.8 Hz / sec) when the compressor 27 is started up. This control under comparison is a control that is generally performed when the compressor 27 is started up. In addition, in the control under comparison, the control is switched from forced commutation to speed control when the rotational speed reaches a predetermined rotational speed (e.g., 17 Hz). Note that the predetermined rotational speed (e.g., 17 Hz) in the control under comparison is higher than the predetermined rotational speed in the embodiment (e.g., 12 Hz, an example of the first rotational speed) and lower than the predetermined rotational speed (e.g., 22 Hz, an example of the second rotational speed). In other words, in the dryer 100 of this embodiment, a predetermined rotational speed (e.g., 12 Hz, an example of the first rotational speed) is lower than a predetermined rotational speed in a typical comparative control (e.g., 17 Hz). By making the predetermined rotational speed (e.g., 12 Hz, an example of the first rotational speed) lower than a predetermined rotational speed in a typical comparative control (e.g., 17 Hz), the rotational force due to the d-axis current is increased. Furthermore, a predetermined rotational speed higher than the predetermined rotational speed (e.g., 22 Hz, an example of the second rotational speed) is higher than a predetermined rotational speed in a typical comparative control (e.g., 17 Hz). By setting the rotational speed to a predetermined speed (e.g., 22Hz, an example of a second rotational speed) higher than the predetermined speed in a typical comparative control (e.g., 17Hz), and setting the acceleration to a greater acceleration (an example of a second acceleration) than a predetermined acceleration (an example of a first acceleration), the compressor can be started stably even when the compressor load is high (e.g., at high temperatures or when compressing refrigerant with a single-rotating piston).

[0044] Figure 7 shows an example of a compressor 27 of the embodiment. The compressor 27 shown in Figure 7 is equipped with a rotating piston 27a. The compressor 27 shown in Figure 7 is a single rotary compressor equipped with one rotating piston 27a. Part 7(a) of Figure 7 shows the state in which refrigerant is taken in from the intake port. Part 7(b) of Figure 7 shows the state in which the refrigerant is compressed by the rotation of the rotating piston 27a. Part 7(c) of Figure 7 shows the state in which the compressed refrigerant is discharged from the exhaust port by the further rotation of the rotating piston 27a. As can be seen from Figure 7, the rotating piston 27a is subjected to a particularly large load from the time the refrigerant is taken in from the intake port, compressed, and then discharged from the exhaust port. The dryer 100 of the embodiment is a dryer that has the effect of being able to stably start the compressor, and is particularly effective when the load on the compressor 27 is large, such as when the compressor 27 is equipped with one rotating piston 27a or when the compressor 27 is at high temperature.

[0045] Another compressor that can be used for comparison is one that has a balancer to suppress rotational fluctuations, i.e., load fluctuations (to prevent the load from becoming too large). However, this would result in an expensive and large compressor. In contrast, the compressor 27 of the embodiment has a smaller balancer, or does not require one at all. In other words, the dryer 100 of the embodiment can use a less expensive and smaller compressor compared to a compressor with a large balancer.

[0046] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0047] 1...Outer casing, 2...Inlet / Outlet, 3...Door, 4...Water receiving tank, 5...Drum motor, 6...Rotating shaft, 7...Drum, 8...Through hole, 9...Baffle, 10...Water supply valve, 11...Water supply valve motor, 12...Water filling case, 13...Water filling port, 14...Drain pipe, 15...Drain valve, 16...Drain valve motor, 17...Main duct, 18...Front duct, 19...Fan casing, 20...Air intake, 21...Exhaust port, 22...Fan motor, 23...Rotating shaft, 24...Fan, 25...Rear duct, 26...Circulation duct, 27...Compressor, 28...Compressor motor, 29...Condenser, 30...Refrigerant pipe, 31...Heating fins, 34...Inlet VATER circuit, 35a~35f...IGBT, 36a~36f...Flywheel diode, 37u, 37v, 37w...Shunt resistor, 38...Inverter circuit, 39...Shunt resistor, 40...Inverter circuit, 41u, 41v, 41w...Shunt resistor, 42A, 42B...Control circuit, 43...Drive power supply circuit, 44...Reactor, 45...Full-wave rectifier circuit, 46a, 46b...Capacitor, 47...Full-wave rectifier circuit, 48...IGBT, 49a, 49b...Resistor, 50a, 50b...Resistor, 51u, 51v, 51w...Position sensor, 52...Current sensor, 60...Drive unit, 100...Dryer.

Claims

1. A compressor having a single-rotating piston and a compressor motor that rotates the single-rotating piston, A control unit performs a first control to increase the rotational speed of the compressor motor with a first acceleration when the compressor is started, and when the rotational speed reaches a predetermined first rotational speed, it performs a second control to increase the rotational speed to a predetermined second rotational speed higher than the first rotational speed with a second acceleration greater than the first acceleration. Equipped with, The control unit, Based on the d-axis current flowing through the compressor motor, the first control is performed to increase the rotational speed with the first acceleration. Based on the q-axis current flowing through the compressor motor, the second control is performed to increase the rotational speed with the second acceleration. The rotation due to the first acceleration is performed by forced commutation, and the second acceleration is performed by velocity control. dryer.

2. The control unit, When the rotational speed is increased to the second rotational speed using the second acceleration, control is performed to increase the rotational speed to a predetermined third rotational speed higher than the second rotational speed using the first acceleration. The dryer according to claim 1.

3. The control unit, Whether or not the rotational speed has reached a predetermined third rotational speed higher than the second rotational speed is determined based on whether or not a value obtained by dividing the third rotational speed minus the second rotational speed by the first acceleration has elapsed. If the rotational speed has been increased to the second rotational speed using the second acceleration, control is performed to increase the rotational speed using the first acceleration until it is determined that the rotational speed has reached the third rotational speed. The dryer according to claim 1.

4. A control method performed by a dryer equipped with a compressor having a single-rotating piston and a compressor motor for rotating the single-rotating piston, A control method comprising: performing a first control to increase the rotational speed of the compressor motor with a first acceleration when the compressor is started; and, when the rotational speed reaches a predetermined first rotational speed, performing a second control to increase the rotational speed to a predetermined second rotational speed higher than the first rotational speed with a second acceleration greater than the first acceleration, Based on the d-axis current flowing through the compressor motor, the first control is performed to increase the rotational speed with the first acceleration. Based on the q-axis current flowing through the compressor motor, the second control is performed to increase the rotational speed with the second acceleration. The rotation due to the first acceleration is performed by forced commutation, and the second acceleration is performed by velocity control. Control method.

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