FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION [See section 10, Rule 13] POWER CONVERTER, MOTOR DRIVER, AND REFRIGERATION CYCLE APPLIED EQUIPMENT MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. 2 DESCRIPTION Field [0001] The present disclosure relates to a power 5 converter for converting alternating-current power into desired power, a motor driver, and a refrigeration cycle applied equipment. Background 10 [0002] A power converter includes: a converter that converts an alternating-current voltage output from an alternating-current power supply into a direct-current voltage; a smoothing unit that smooths an output voltage of the converter; and an inverter that converts the direct15 current voltage output via the smoothing unit into an alternating-current voltage and applies the alternatingcurrent voltage to a load. [0003] Patent Literature 1 below describes a power converter for compressor driving. In this type of power 20 converter, when a direct-current voltage applied to an inverter vibrates or when a load torque is to be controlled, a vibration component is superimposed on a current flowing through the inverter. When the vibration component and a rotational speed of a motor match or are close to each 25 other, they mutually affect each other, which causes generation of beat sound in the motor. [0004] In view of the above problem, in Patent Literature 1, when a frequency that is an integral multiple of an operation frequency of the motor is in a range of a 30 value close to twice a power supply frequency, generation of the beat sound is suppressed by varying the operation frequency of the motor at a rate equal to an increase and a decrease. 3 Citation List Patent Literature [0005] Patent Literature 1: Japanese Patent Application 5 Laid-open No. 2007-104756 Summary Technical Problem [0006] However, in the technique of Patent Literature 1, 10 it is necessary to minutely fluctuate the rotational speed of the motor in order to suppress the beat sound. Therefore, time required to accelerate the motor to a target rotational speed becomes long, and there is a problem that the motor cannot be smoothly accelerated. A 15 similar problem arises when the motor is decelerated. [0007] The present disclosure has been made in view of the above, and an object thereof is to obtain a power converter capable of smoothly accelerating and decelerating a motor while suppressing generation of beat sound. 20 Solution to Problem [0008] In order to solve the above-described problem and achieve the object, a power converter according to the present disclosure includes a converter, a capacitor, an 25 inverter, and a controller. The converter rectifies an alternating-current voltage applied from the alternatingcurrent power supply. The capacitor is connected to output ends of the converter. The inverter is connected to both ends of the capacitor. The controller controls an 30 operation of the inverter. A voltage output from the converter includes a ripple component due to a voltage fluctuation of the alternating-current voltage. When the controller performs acceleration and deceleration control 4 on a motor, the controller changes a command value for a physical quantity associated with a change in the rotational speed from a command value for the physical quantity during a normal control, in a first period in 5 which the rotational speed of the motor is in a first speed range. Advantageous Effects of Invention [0009] According to the power converter of the present 10 disclosure, it is possible to smoothly accelerate and decelerate the motor while reducing generation of beat sound. Brief Description of Drawings 15 [0010] FIG. 1 is a diagram illustrating a configuration of a power converter according to a first embodiment. FIG. 2 is a block diagram illustrating a configuration example of a control calculator according to the first embodiment. 20 FIG. 3 is a graph illustrating a typical generation pattern of a rotational speed command. FIG. 4 is a graph illustrating an example of a generation pattern of a rotational speed command in the first embodiment. 25 FIG. 5 is a view for explaining a cause of generation of beat sound that may be generated in a configuration of the first embodiment. FIG. 6 is a graph illustrating another example of a generation pattern of the rotational speed command in the 30 first embodiment. FIG. 7 is a block diagram illustrating an example of a hardware configuration that implements functions of the control calculator according to the first embodiment. 5 FIG. 8 is a block diagram illustrating another example of a hardware configuration that implements functions of the control calculator according to the first embodiment. FIG. 9 is a block diagram illustrating a configuration 5 example of a control calculator according to a second embodiment. FIG. 10 is a graph illustrating an example of a generation pattern of a rotational speed command and a voltage limiting coefficient in the second embodiment. 10 FIG. 11 is a graph illustrating another example of a generation pattern of the rotational speed command and the voltage limiting coefficient in the second embodiment. FIG. 12 is a diagram illustrating a configuration example of a refrigeration cycle applied equipment 15 according to a third embodiment. Description of Embodiments [0011] Hereinafter, a power converter, a motor driver, and a refrigeration cycle applied equipment according to 20 embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. [0012] First Embodiment. FIG. 1 is a diagram illustrating a configuration of a power converter 1 according to a first embodiment. The 25 power converter 1 is connected to an alternating-current power supply 100 and a compressor 120. The compressor 120 is an example of a load. The compressor 120 includes a motor 110. The power converter 1 converts a first alternating-current voltage, which is a power supply 30 voltage applied from the alternating-current power supply 100, into a second alternating-current voltage having a desired amplitude and phase, and applies the second alternating-current voltage to the motor 110. 6 [0013] The power converter 1 includes a voltage-current detector 16, a converter 10, a capacitor 12, a voltage detector 18, an inverter 14, current detectors 20u, 20v, and 20w, and a controller 30. The power converter 1 and 5 the motor 110 included in the compressor 120 constitute a motor driver 2. [0014] The voltage-current detector 16 detects a first alternating-current voltage applied from the alternatingcurrent power supply 100 to the converter 10, and detects 10 an alternating current flowing in and out of the converter 10. Each detected value obtained by the voltage-current detector 16 is input to the controller 30. [0015] The converter 10 rectifies the first alternatingcurrent voltage applied from the alternating-current power 15 supply 100. The converter 10 is configured by using a plurality of bridge-connected rectifying elements 10a. Note that arrangement and connection of the rectifying elements 10a in the converter 10 are known, and a description thereof will be omitted here. 20 [0016] Further, the converter 10 may have a boosting function of boosting a rectified voltage, together with the rectifying function. A converter having the boosting function can be configured by including, in addition to the rectifying element 10a or instead of the rectifying element 25 10a, one or more switching elements or a plurality of switching elements in which a transistor element and a diode are connected in anti-parallel. Note that arrangement and connection of the switching elements in the converter having the boosting function are known, and a 30 description thereof is omitted here. [0017] A rectified voltage rectified by the converter 10 is applied to the capacitor 12. [0018] The capacitor 12 is connected to the output ends 7 of the converter 10. The capacitor 12 holds the rectified voltage output from the converter 10. Examples of the capacitor 12 include an electric field capacitor and a film capacitor. 5 [0019] The voltage detector 18 detects a capacitor voltage Vc, which is a voltage of the capacitor 12. A detected value of the voltage detector 18 is input to the controller 30. [0020] The inverter 14 is connected to both ends of the 10 capacitor 12. The inverter 14 converts a voltage output from the capacitor 12 into a second alternating-current voltage having a desired amplitude and phase, and applies the second alternating-current voltage to the motor 110 of the compressor 120. The inverter 14 includes a plurality 15 of switching elements 14a in which a transistor element and a diode are connected in anti-parallel. Note that arrangement and connection of the switching elements 14a in the inverter 14 are known, and a description thereof will be omitted here. 20 [0021] Electric wiring connecting the inverter 14 and the motor 110 is provided with the current detectors 20u, 20v, and 20w. The current detectors 20u, 20v, and 20w each detect a current for each one phase among three-phase currents iu, iv, and iw output from the inverter 14. 25 Detected values of the current detectors 20u, 20v, and 20w are input to the controller 30. [0022] Note that FIG. 1 illustrates a configuration including the three current detectors 20u, 20v, and 20w, but the present disclosure is not limited to this 30 configuration. By using the relationship of iu+iv+iw=0, which is a three-phase equilibrium condition, any one of the three current detectors 20u, 20v, and 20w may be omitted. 8 [0023] The compressor 120 is a load having the motor 110 for compressor driving. The motor 110 rotates in accordance with an amplitude and a phase of the second alternating-current voltage applied from the inverter 14, 5 and performs a compression operation. [0024] The controller 30 includes a control calculator 32 and a driver 34, and controls an operation of the inverter 14 by using a detected value detected by each detector. 10 [0025] The control calculator 32 generates a voltage command for performing pulse width modulation (PWM) control on the inverter 14. The control calculator 32 generates a voltage command for matching a rotational speed of the motor 110 with a rotational speed command, and outputs the 15 voltage command to the driver 34. [0026] The driver 34 generates a drive signal for driving the plurality of switching elements 14a of the inverter 14, by using the voltage command generated by the control calculator 32. The rotational speed of the motor 20 110 is controlled as the switching element 14a of the inverter 14 is PWM-controlled. [0027] Note that, in the above control, the controller 30 may not use all the detected values acquired from the individual detectors, and may perform control by using some 25 detected values. [0028] Next, a configuration and an operation of the control calculator 32 that solve the above-described problem will be described. FIG. 2 is a block diagram illustrating a configuration example of the control 30 calculator 32 according to the first embodiment. As illustrated in FIG. 2, the control calculator 32 includes a rotational speed command generator 321, a speed controller 322, a torque controller 323, and a speed estimator 324. 9 [0029] The rotational speed command generator 321 generates a rotational speed command to be given to the motor 110. The rotational speed command generated by the rotational speed command generator 321 is input to the 5 speed controller 322. [0030] The speed controller 322 generates a basic torque command for matching an estimated rotational speed with the rotational speed command, and outputs the basic torque command to the torque controller 323. To the computation 10 of the basic torque command, speed control by a general proportional integral differential (PID) controller or a general proportional integral (PI) controller can be applied. However, a controller other than the PID controller or the PI controller may be used as long as 15 desired control performance can be obtained. [0031] The torque controller 323 generates a voltage command for matching an output torque of the motor 110 with the basic torque command, and outputs the voltage command to the driver 34. In order to control the output torque of 20 the motor 110 to a desired value, it is known that control is preferably performed on a dq-axis current which is a current in a dq-axis coordinate system. However, it is needless to say that control may be performed with a current in a coordinate system other than the dq-axis 25 coordinate system. A general PI controller can be used to control of the dq-axis current. However, a controller other than the PI controller may be used as long as desired control performance can be obtained. [0032] The speed estimator 324 generates an estimated 30 rotational speed on the basis of a voltage command and a detected current. The estimated rotational speed is an estimated value of the rotational speed of the motor 110. For the computation of the estimated rotational speed, a 10 case of using a PI controller and a case of connecting the PI controller and an integrator in series are known. However, a configuration other than these cases may be used as long as desired control performance can be obtained. 5 [0033] FIG. 3 is a graph illustrating a typical generation pattern of the rotational speed command. Further, FIG. 4 is a graph illustrating an example of a generation pattern of the rotational speed command in the first embodiment. In FIGS. 3 and 4, a horizontal axis 10 represents time, and a vertical axis represents a rotational speed command. FIGS. 3 and 4 illustrate a timevarying waveform of the rotational speed command when the motor 110 is accelerated to a target rotational speed Rpstar. Further, on the right side of FIGS. 3 and 4, an enlarged 15 waveform of a portion indicated by a broken line circle in the graph on the left side is illustrated. Note that, in the following description, the description is made by assuming that an actual rotational speed of the motor 110 substantially matches the rotational speed command. 20 [0034] When the motor 110 is accelerated to the target rotational speed Rpstar, typically, the rotational speed command is increased in proportion to the time as illustrated in FIG. 3. In the graph on the right, Rpsvib is a rotational speed command when the beat sound described 25 above becomes large. The beat sound is not generated in a pinpoint manner, but is generated in a range of a rotational speed command having a certain width. Therefore, in the control of the first embodiment, a range having a width of ±Δrps, that is, a range of 2Δrps is set before and 30 after Rpsvib, and this range is defined as a “first speed range”. Furthermore, a period corresponding to the first speed range, that is, a period during which the rotational speed of the motor 110 is in the first speed range is 11 defined as a “first period” and represented by tvib. [0035] FIG. 5 is a view for explaining a cause of generation of beat sound that may be generated in a configuration of the first embodiment. In FIG. 5, a 5 horizontal axis represents time, and a vertical axis represents an amplitude of each waveform. In the upper part, a power supply voltage is indicated by a solid line, and a rectified voltage is indicated by a broken line. In the lower part, a U-phase voltage command is indicated by a 10 solid line, a V-phase voltage command is indicated by a broken line, and a W-phase voltage command is indicated by a one-dot chain line. [0036] When a power supply frequency, which is a frequency of the power supply voltage, is represented by fs, 15 one cycle of the power supply voltage is represented by 1/fs. At this time, the rectified voltage output from the converter 10 includes a ripple component. In FIG. 5, a cycle of a voltage command of each phase matches a cycle of the power supply voltage. For this reason, the ripple 20 component of the rectified voltage becomes a trough at a position of a peak and a trough of a waveform of the Uphase voltage command, and this state is repeated. As illustrated in FIG. 5, the state has a high possibility of generation of the beat sound. 25 [0037] As illustrated in FIG. 5, when the cycle of the voltage command matches the cycle of the power supply voltage, the beat sound becomes large. Note that, even without complete matching, when the cycle of the voltage command and the cycle of the power supply voltage are close 30 to each other, there is a high possibility of generation of the beat sound. Therefore, in the first embodiment, as illustrated in FIG. 4, an acceleration/deceleration rate of the rotational speed command is changed from a 12 predetermined value, that is, changed from an acceleration/deceleration rate during a normal control, in the first period (t'vib) in which the rotational speed of the motor 110 is in the first speed range (2Δrps). In the 5 first embodiment, the rotational speed command is an example of a command value for a physical quantity associated with a change in the rotational speed. [0038] Comparing the first period tvib illustrated in FIG. 3 with the first period t'vib illustrated in FIG. 4, a 10 relationship of t'vib