JP2020072553A - Motor compressor - Google Patents

Abstract

To early warm up a capacitor independently of a position of a rotor.SOLUTION: When an estimated temperature of a capacitor 32 is equal to or less than a predetermined temperature, a control device 25 performs energization pattern determination processing of determining an energization pattern to a motor 16 to be any one of six patterns in which only any one of currents flown in a coil 19 of respective phases always becomes the maximum allowable motor current value positively or negatively, depending on an estimated position of a rotor. The control device 25 further performs maximum allowable value determination processing of determining the maximum allowable motor current value on the basis of information on the estimated temperature of the capacitor 32, and phase shift processing of shifting a phase of a PWM signal of one phase in a PWM signal of three phases generated depending on the energization pattern determined by the energization pattern determination processing. Phase ranges of the respective energization patterns are equivalent to each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric compressor.

  The electric compressor includes a compression unit that compresses fluid, a motor that drives the compression unit, an inverter circuit having a switching element, and a control unit that controls the inverter circuit. The switching element performs a switching operation to drive the motor. The coils of each phase of the motor are connected to the output side of the inverter circuit. The control unit outputs a three-phase PWM signal to the inverter circuit to control the inverter circuit. Then, based on the PWM signal output from the control unit, the switching element performs a switching operation, so that the DC current from the DC power supply is converted into an AC current, and the AC current is supplied to the coils of each phase of the motor. As a result, the motor is driven.

  A capacitor connected in parallel to the DC power source is provided on the input side of the inverter circuit. By the way, in an environment of extremely low temperature (for example, 0 ° C. or lower), the equivalent series resistance (ESR) of the capacitor rapidly increases. When a current flows through the capacitor with the equivalent series resistance of the capacitor rapidly increasing, a surge voltage is generated, and when the surge voltage exceeds the withstand voltage of the switching element, the switching element may fail.

  Therefore, for example, in Patent Document 1, when the temperature of the capacitor is equal to or lower than a predetermined temperature, a phase shift process of shifting the phase of at least one phase PWM signal of the three phase PWM signals output to the inverter circuit is performed. Running. Specifically, the period in which the polarities of the output voltages of the three phases (U phase, V phase, W phase) output from the inverter circuit are all the same (all High polarity or Low polarity) is shortened, Among the PWM signals output to the inverter circuit, the phase of at least one phase PWM signal is shifted. According to this, when the switching element performs the switching operation based on the PWM signal after the phase shift processing is executed, a larger amount of current will flow in the capacitor than before the phase shift processing is executed, and the capacitor will operate earlier. Be warmed to.

JP, 2016-32420, A

  However, the value of the current flowing through the coil of each phase changes depending on the position of the rotor, and accordingly, the value of the current flowing through the capacitor also changes depending on the position of the rotor. Therefore, even if the phase shift process is executed as in Patent Document 1, it may be difficult for the capacitor to warm up depending on the position of the rotor.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric compressor that can warm a condenser early regardless of the position of the rotor.

  An electric compressor that solves the above problem includes a compression unit that compresses fluid, a motor that drives the compression unit, and a switching element that performs a switching operation to drive the motor, and each of the motors on the output side. Inverter circuit to which a phase coil is connected, a capacitor provided on the input side of the inverter circuit and connected in parallel to a DC power supply, and a three-phase PWM signal is output to the inverter circuit to output the inverter circuit. And a rotor position estimation unit that estimates the position of the rotor of the motor, the control unit is estimated by the temperature estimation unit. When the temperature of the condenser is equal to or lower than a predetermined temperature, the position of the rotor estimated by the rotor position estimation unit Accordingly, an energization pattern determination process for determining the energization pattern for the motor to be one of the six patterns in which only one of the currents flowing through the coils of the respective phases is always positive or negative and has a maximum allowable value, Of the maximum allowable value determination process of determining the maximum allowable value based on the information from the temperature estimation unit and the three-phase PWM signal generated according to the energization pattern determined in the energization pattern determination process And a phase shift process of shifting the phase of the PWM signal of one phase are performed, and the phase ranges of the energization patterns are equal to each other.

  For example, of the PWM signals of the three phases generated at the position of the rotor where the value of any one of the currents flowing through the coils of each phase is the minimum, the phase of the PWM signal of the phase with the minimum current value Consider a case in which is shifted to supply a direct current to the motor. Here, the inventors of the present invention have a small value of the current when flowing as a regenerative current from the coil of the phase of which the phase of the PWM signal having the smallest current value is shifted to the capacitor, so that the heat generation of the capacitor is small and the capacitor I found it difficult to warm up.

  Therefore, even if the rotor position estimated by the rotor position estimating unit is, for example, the position where the value of any one of the currents flowing through the coils of the respective phases is the minimum, the control unit performs the energization pattern determination process. By executing the above, the energization pattern for the motor becomes the energization pattern for the position of the rotor in which only one of the currents flowing through the coils of each phase is always positive or negative and has the maximum allowable value. Further, since the control unit executes the phase shift process of shifting the phase of the PWM signal of one phase among the PWM signals of three phases generated according to the energization pattern determined by the energization pattern determination process, the control of the current Of the three-phase PWM signals generated at the position of the rotor having the minimum value, the phase of the PWM signal having the minimum current value is not shifted. Then, the control unit outputs a three-phase PWM signal having a phase after the phase shift processing to the inverter circuit, and supplies a direct current to the motor with the energization pattern determined by the energization pattern determination processing. For this reason, the value of the current flowing from the coil to the capacitor as a regenerative current becomes large, and the capacitor easily warms up. Therefore, the condenser can be warmed up early regardless of the position of the rotor.

  In the electric compressor, the control unit may determine, in the energization pattern determination process, the energization pattern that is closest to the position of the rotor estimated by the rotor position estimation unit among the six patterns. ..

  According to this, when the control unit controls the inverter circuit so as to supply the direct current to the motor with the energization pattern determined by the energization pattern determination process, the rotor is prevented from rotating significantly. Can be suppressed. Therefore, it is possible to suppress the generation of abnormal noise from the compression unit due to the large rotation of the rotor.

  In the electric compressor, the control unit, in the phase shift process, a phase of one phase PWM signal among three phase PWM signals generated according to the energization pattern determined in the energization pattern determination process. May be shifted by 180 ° with respect to the phase of the PWM signal of the other phase.

  According to this, the time during which the current flows through the capacitor can be lengthened, so that the capacitor is more easily warmed. Therefore, the capacitor can be warmed up earlier.

  According to the present invention, the capacitor can be warmed up early regardless of the position of the rotor.

The side sectional view showing the electric compressor in an embodiment. The circuit diagram which shows the electric constitution of an electric compressor. The graph which shows the relationship between the electric current which flows into a motor, and the position of a rotor. The graph which shows the relationship between the electric current which flows into a motor in warm-up control mode, and the position of a rotor. The figure which shows the relationship between the position of a rotor in the warming-up control mode, and the electricity supply pattern to a motor. The graph which shows the relationship of the change of the electric current which flows into a motor when the position of a rotor is 0 degree, the change of a 3-phase PWM signal, and the change of the electric current flow to a capacitor | condenser. The flowchart for demonstrating control of a control apparatus. FIG. 7 is a diagram showing a current flow at timing T1 in FIG. 6. The figure which shows the flow of the electric current at the timing T2 in FIG. FIG. 7 is a diagram showing a current flow at timing T3 in FIG. 6. FIG. 7 is a diagram showing a current flow at timing T4 in FIG. 6. FIG. 7 is a diagram showing a current flow at timing T5 in FIG. 6. FIG. 7 is a diagram showing a current flow at timing T6 in FIG. 6. When the control device in the comparative example does not execute the phase shift process, the change in the current flowing through the motor in the energization pattern in which the rotor position is 0 °, the change in the three-phase PWM signal, and the change in the current flow to the capacitor The graph which shows the relation of change. The figure which shows typically the flow of the electric current at the time of timing T11 in FIG. The figure which shows typically the flow of the electric current at the time of timing T12 in FIG. The figure which shows typically the flow of the electric current at the time of timing T13 in FIG. The figure which shows typically the flow of the electric current at the time of timing T14 in FIG. The figure which shows typically the flow of the electric current at the time of timing T15 in FIG. The figure which shows typically the flow of the electric current at the timing T16 in FIG. 7 is a graph showing the relationship between changes in the current flowing through the motor and changes in the three-phase PWM signal, and changes in the current flow to the capacitor when the energization pattern is that the rotor position is 30 ° in the comparative example. FIG. 23 is a diagram schematically showing a current flow at timing T21 in FIG. 21. FIG. 22 is a diagram schematically showing a current flow at timing T22 in FIG. 21. FIG. 23 is a diagram schematically showing a current flow at timing T23 in FIG. 21.

Hereinafter, an embodiment in which an electric compressor is embodied will be described with reference to FIGS. 1 to 24. The electric compressor of this embodiment is used, for example, in a vehicle air conditioner.
As shown in FIG. 1, the housing 11 of the electric compressor 10 has a bottomed tubular discharge housing 12, and a bottomed tubular motor housing 13 connected to the discharge housing 12. The discharge housing 12 and the motor housing 13 are made of a metal material (for example, aluminum). The motor housing 13 has a bottom wall 13e and a side wall 13a extending in a tubular shape from the outer peripheral edge of the bottom wall 13e.

  A rotary shaft 14 is housed in the motor housing 13. Further, in the motor housing 13, a compression unit 15 that is driven by the rotation of the rotation shaft 14 to compress the refrigerant as a fluid, and a motor 16 that rotates the rotation shaft 14 to drive the compression unit 15 are housed. Has been done. The compression unit 15 and the motor 16 are arranged side by side in the axial direction, which is the direction in which the rotation axis of the rotation shaft 14 extends. The motor 16 is arranged closer to the bottom wall 13e of the motor housing 13 than the compression section 15.

  The compression unit 15 is, for example, a scroll type configured by a fixed scroll (not shown) fixed in the motor housing 13, and a movable scroll (not shown) arranged so as to face the fixed scroll. The compression unit 15 is not limited to the scroll type and may be, for example, a piston type or a vane type.

  The motor 16 includes a tubular stator 17 and a rotor 18 arranged inside the stator 17. The rotor 18 rotates integrally with the rotating shaft 14. The stator 17 surrounds the rotor 18. The rotor 18 has a rotor core 18a fixed to the rotating shaft 14 and a plurality of permanent magnets 18b provided on the rotor core 18a. The stator 17 has a tubular stator core 17a and a coil 19 wound around the stator core 17a. Then, by supplying electric power to the coil 19, the rotor 18 rotates, and the rotating shaft 14 rotates integrally with the rotor 18.

  A suction port 13h is formed on the side wall 13a. The suction port 13h sucks the refrigerant into the motor housing 13. One end of the external refrigerant circuit 20 is connected to the suction port 13h. The discharge housing 12 is formed with a discharge port 12h. The other end of the external refrigerant circuit 20 is connected to the discharge port 12h.

  The refrigerant sucked into the motor housing 13 from the external refrigerant circuit 20 through the suction port 13h is compressed by the compressor 15 by driving the compressor 15, and flows out to the external refrigerant circuit 20 through the discharge port 12h. Then, the refrigerant flowing out to the external refrigerant circuit 20 flows back into the motor housing 13 through the heat exchanger and the expansion valve of the external refrigerant circuit 20 and the suction port 13h. The electric compressor 10 and the external refrigerant circuit 20 form a vehicle air conditioner 21.

  A bottomed cylindrical cover 22 is attached to the bottom wall 13e of the motor housing 13. The bottom wall 13e of the motor housing 13 and the cover 22 form an accommodation space 22a that accommodates the inverter circuit 24 that drives the motor 16. The compression unit 15, the motor 16, and the inverter circuit 24 are arranged in this order in the axial direction of the rotary shaft 14.

  As shown in FIG. 2, the coil 19 of the motor 16 has a three-phase structure including a u-phase coil 19u, a v-phase coil 19v, and a w-phase coil 19w. In the present embodiment, the u-phase coil 19u, the v-phase coil 19v, and the w-phase coil 19w are Y-connected.

  The inverter circuit 24 has a plurality of switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2. The plurality of switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 perform a switching operation to drive the motor 16. The plurality of switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 are IGBTs (power switching elements). Diodes Du1, Du2, Dv1, Dv2, Dw1, Dw2 are connected to the plurality of switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2, respectively. The diodes Du1, Du2, Dv1, Dv2, Dw1, Dw2 are connected in parallel to the switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2.

  Each switching element Qu1, Qv1, Qw1 constitutes the upper arm of each phase. Each switching element Qu2, Qv2, Qw2 constitutes the lower arm of each phase. The switching elements Qu1 and Qu2, the switching elements Qv1 and Qv2, and the switching elements Qw1 and Qw2 are connected in series, respectively. The gates of the switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 are electrically connected to the control device 25. The collectors of the switching elements Qu1, Qv1, Qw1 are electrically connected to the positive electrode of the DC power supply 31, which is the vehicle battery. The emitters of the switching elements Qu2, Qv2, Qw2 are electrically connected to the negative electrode of the DC power supply 31 via the current sensors 41u, 41v, 41w. The emitters of the switching elements Qu1, Qv1, Qw1 and the collectors of the switching elements Qu2, Qv2, Qw2 are electrically connected to the u-phase coil 19u, the v-phase coil 19v, and the w-phase coil 19w from the intermediate points connected in series, respectively. Connected to each other. Therefore, the coil 19 of each phase of the motor 16 is connected to the output side of the inverter circuit 24.

  The electric compressor 10 includes a capacitor 32 that is connected in parallel with a DC power supply 31. The capacitor 32 is provided on the input side of the inverter circuit 24. The capacitor 32 is, for example, an electrolytic capacitor.

  The electric compressor 10 includes a voltage sensor 33 that detects an input voltage from the DC power supply 31. The voltage sensor 33 is electrically connected to the control device 25 and transmits the detected detection result to the control device 25.

  The controller 25 controls the drive voltage of the motor 16 by pulse width modulation. Specifically, control device 25 generates a three-phase PWM signal by a high frequency triangular wave signal called a carrier wave signal and a voltage command signal for instructing a voltage. The PWM signal is a rectangular-wave signal whose pulse width is controlled, and is a signal for controlling the output voltage output from the inverter circuit 24. The three-phase PWM signals have a predetermined phase and a predetermined duty ratio, respectively. Then, the control device 25 outputs the generated three-phase PWM signals to the switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2, and switches the switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2. Performs operation control (on / off control). Therefore, the control device 25 is a control unit that outputs a three-phase PWM signal to the inverter circuit 24 and controls the inverter circuit 24.

  As a result, the DC current from the DC power supply 31 is converted into an AC current. Therefore, each of the switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 performs a switching operation to convert the DC current from the DC power supply 31 into an AC current. Then, the converted AC current is supplied to the motor 16 to drive the motor 16.

  The control device 25 is electrically connected to an air conditioning ECU 26 that controls the entire vehicle air conditioning device 21. The air conditioning ECU 26 is configured so as to be able to grasp the temperature inside the vehicle, the set temperature, and the like, and based on these parameters, transmits information regarding the target rotation speed of the motor 16 to the control device 25. Further, the air conditioning ECU 26 transmits various commands such as an operation command of the motor 16 and a stop command of the motor 16 to the control device 25.

  The controller 25 estimates the position θ of the rotor 18 of the motor 16 based on the current flowing from the inverter circuit 24 to the motor 16 without using a rotation angle sensor such as a resolver that detects the position θ of the rotor 18 of the motor 16. By doing so, the rotation control of the motor 16 can be performed. Therefore, the electric compressor 10 of the present embodiment performs position sensorless control for controlling the rotation of the motor 16 based on the position θ of the rotor 18 estimated by the control device 25. Therefore, the control device 25 also functions as a rotor position estimation unit that estimates the position θ of the rotor 18 of the motor 16.

  Specifically, in the control device 25, the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw flowing through the motor 16 detected by the current sensors 41u, 41v, 41w, and the voltage sensor 33 are detected. A rotor position estimation program for estimating the position θ of the rotor 18 from the input voltage is stored in advance. Then, the control device 25, the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw flowing through the motor 16 detected by the current sensors 41u, 41v, 41w, and the input voltage detected by the voltage sensor 33, The position θ of the rotor 18 is estimated based on the rotor position estimation program.

  The control device 25 uses the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw flowing through the motor 16 detected by the current sensors 41u, 41v, and 41w, and the estimated position θ of the rotor 18, based on the estimated position θ. The U-phase current Iu, the V-phase current Iv, and the W-phase current Iw are converted into a d-axis current (excitation component current) and a q-axis current (torque component current). The d-axis current (excitation component current) is a current vector component in the current flowing through the motor 16 in the same direction as the magnetic flux generated by the permanent magnet 18b. The q-axis current (torque component current) is a current vector component of the current flowing through the motor 16 that is orthogonal to the d-axis.

  The controller 25 determines the d-axis current (excitation component current) in the motor 16 based on the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw flowing through the motor 16 detected by the current sensors 41u, 41v, 41w. On / off control of each switching element Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 is performed so that the q-axis current (torque component current) becomes a target value. As a result, the motor 16 rotates at the target rotation speed transmitted from the air conditioning ECU 26.

  FIG. 3 shows the relationship between the current flowing through the motor 16 and the position θ of the rotor 18. In FIG. 3, the waveform of the U-phase current Iu is shown by a solid line, the waveform of the V-phase current Iv is shown by a one-dot chain line, and the waveform of the W-phase current Iw is shown by a two-dot chain line. As shown in FIG. 3, the waveform of the U-phase current Iu, the waveform of the V-phase current Iv, and the waveform of the W-phase current Iw are formed by sine waves that are 120 ° out of phase with each other. The U-phase current Iu, the V-phase current Iv, and the W-phase current Iw have a relationship of Iu + Iv + Iw = 0 regardless of the position θ of the rotor 18.

  In the present embodiment, for example, when the relationship of Iu: Iv: Iw = + 1: -0.5: -0.5 holds, the position θ of the rotor 18 becomes 0 °. Further, for example, when the relationship of Iu: Iv: Iw = + √3 / 2: 0: −√3 / 2 holds, the position θ of the rotor 18 becomes 30 °. Further, for example, when the relationship of Iu: Iv: Iw = + 0.5: +0.5: -1 holds, the position θ of the rotor 18 becomes 60 °.

  As shown in FIG. 2, the electric compressor 10 includes a temperature sensor 34. The temperature sensor 34 is electrically connected to the control device 25. The temperature sensor 34 detects the temperature for estimating the temperature of the capacitor 32, for example. Specifically, the temperature sensor 34 detects the temperature of the board on which the capacitor 32 is mounted. Information about the temperature detected by the temperature sensor 34 is transmitted to the control device 25.

  A temperature estimation program for estimating the temperature of the condenser 32 based on the information about the temperature transmitted from the temperature sensor 34 is stored in the control device 25 in advance. Then, the control device 25 estimates the temperature of the capacitor 32 based on the temperature detected by the temperature sensor 34 and the temperature estimation program. Therefore, the temperature sensor 34 and the control device 25 form a temperature estimation unit that estimates the temperature of the condenser 32.

  Further, the control device 25 stores a program for executing a maximum allowable value determination process for determining a maximum allowable motor current value (maximum allowable value) based on the estimated temperature information of the capacitor 32. Specifically, the control device 25 stores in advance a calculation program for calculating the maximum allowable motor current value. The maximum allowable motor current value is the maximum value of the current that does not damage the switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 by the surge voltage generated by the equivalent series resistance (ESR) of the capacitor 32. The control device 25 calculates the maximum allowable motor current value based on the estimated temperature of the capacitor 32 and the calculation program stored in advance. Then, the control device 25 controls the inverter circuit 24 so that a current equal to or less than the calculated maximum allowable motor current value flows to the motor 16.

  When the estimated temperature of the capacitor 32 is equal to or lower than a predetermined temperature, the control device 25 controls the inverter circuit 24 so as to supply a direct current to the motor 16 to warm up the capacitor 32. A program for executing the warm-up control mode for performing is stored in advance. Further, when the estimated temperature of the capacitor 32 is higher than a predetermined temperature, the control device 25 controls the inverter circuit 24 so as to supply the AC current to the motor 16 in the normal control mode. A program for executing is stored in advance. Therefore, the control device 25 can switch between the warm-up control mode and the normal control mode based on the estimated temperature of the condenser 32.

  In the warm-up control mode, the controller 25 controls the energization pattern of the motor 16 so that only one of the currents flowing through the coils 19 of each phase is positive or negative in accordance with the estimated position θ of the rotor 18. In advance, a program for executing the energization pattern determination process for determining one of the six patterns that always has the maximum allowable motor current value is stored in advance.

  FIG. 4 shows the relationship between the current flowing through the motor 16 and the position θ of the rotor 18 in the warm-up control mode. Further, FIG. 5 shows the relationship between the position θ of the rotor 18 and the energization pattern to the motor 16 in the warm-up control mode.

  As shown in FIGS. 4 and 5, in the warm-up control mode, the control device 25 determines that the estimated position θ of the rotor 18 is, for example, 330 ° <θ ≦ 360 ° and 0 ° ≦ θ ≦ 30 °. At some time, the energization pattern determination process determines the energization pattern in which the position θ of the rotor 18 is 0 °. The energization pattern in which the position θ of the rotor 18 is 0 ° means that the relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw is Iu: Iv: Iw = + 1: -0.5: -0. It is said that there is a relationship of 5. That is, in the energization pattern in which the position θ of the rotor 18 is 0 °, the U-phase current Iu among the currents flowing through the coils 19 of each phase is always the maximum allowable motor current value.

  In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 30 ° <θ ≦ 90 °, the control device 25 sets the position θ of the rotor 18 to 60 ° by the energization pattern determination process. Determine the energization pattern. The relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw means that the energization pattern in which the position θ of the rotor 18 is 60 ° is Iu: Iv: Iw = + 0.5: +0.5: -1. Say that it is a relationship. That is, in the energization pattern in which the position θ of the rotor 18 is 60 °, the W-phase current Iw among the currents flowing in the coils 19 of each phase is always the maximum allowable motor current value.

  In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 90 ° <θ ≦ 150 °, the control device 25 sets the position θ of the rotor 18 to 120 ° by the energization pattern determination process. Determine the energization pattern. The energization pattern in which the position θ of the rotor 18 is 120 ° means that the relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw is Iu: Iv: Iw = −0.5: +1: −0. It is said that there is a relationship of 5. That is, in the energization pattern in which the position θ of the rotor 18 is 120 °, the V-phase current Iv among the currents flowing through the coils 19 of each phase is always the maximum allowable motor current value.

  In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 150 ° <θ ≦ 210 °, the controller 25 determines the position θ of the rotor 18 to be 180 ° by the energization pattern determination process. Determine the energization pattern. The relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw is the energization pattern in which the position θ of the rotor 18 is 180 °, and Iu: Iv: Iw = −1: +0.5: +0.5. Say that it is a relationship. That is, in the energization pattern in which the position θ of the rotor 18 is 180 °, the U-phase current Iu among the currents flowing through the coils 19 of each phase is always the maximum allowable motor current value.

  In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 210 ° <θ ≦ 270 °, the control device 25 sets the position θ of the rotor 18 to 240 ° by the energization pattern determination process. Determine the energization pattern. The energization pattern in which the position θ of the rotor 18 is 240 ° means that the relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw is Iu: Iv: Iw = −0.5: −0.5: Say it has a +1 relationship. That is, in the energization pattern in which the position θ of the rotor 18 is 240 °, the W-phase current Iw among the currents flowing through the coils 19 of each phase is always the maximum allowable motor current value.

  In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 270 ° <θ ≦ 330 °, the controller 25 determines the position θ of the rotor 18 to be 300 ° by the energization pattern determination process. Determine the energization pattern. The relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw means that the energization pattern in which the position θ of the rotor 18 is 300 ° is Iu: Iv: Iw = + 0.5: −1: +0.5. Say that it is a relationship. That is, in the energization pattern in which the position θ of the rotor 18 is 300 °, the V-phase current Iv among the currents flowing in the coils 19 of each phase is always the maximum allowable motor current value.

  Therefore, in the energization pattern determination process, the control device 25 determines one of the six energization patterns that differ by 60 ° in accordance with the estimated position θ of the rotor 18. The phase range of each energization pattern is 60 °. Therefore, the phase ranges of the energization patterns are the same. Then, in the energization pattern determination process, the control device 25 determines the energization pattern that is the closest to the estimated position θ of the rotor 18 among the six patterns.

  Further, in the warm-up control mode, the control device 25 has a phase shift that shifts the phase of one-phase PWM signal of the three-phase PWM signals generated according to the energization pattern determined in the energization pattern determination process. A program for executing the process is stored in advance.

  FIG. 6 shows the relationship between the change in the current flowing through the motor 16 when the position θ of the rotor 18 is 0 °, the change in the three-phase PWM signal, and the change in the current flow with respect to the capacitor 32. There is. Note that, in FIG. 6, for example, when the U-phase PWM signal is High, the switching element Qu1 configuring the U-phase upper arm is in the ON state, and the switching element Qu2 configuring the U-phase lower arm is It is off. When the U-phase PWM signal is low, the switching element Qu1 that forms the upper arm of the U phase is off and the switching element Qu2 that forms the lower arm of the U phase is on. Similarly, for example, when the V-phase PWM signal is High, the switching element Qv1 forming the V-phase upper arm is on and the switching element Qv2 forming the V-phase lower arm is off. is there. When the V-phase PWM signal is low, the switching element Qv1 that forms the V-phase upper arm is off and the switching element Qv2 that forms the V-phase lower arm is on. Further, when the W-phase PWM signal is High, the switching element Qw1 forming the W-phase upper arm is on and the switching element Qw2 forming the W-phase lower arm is off. When the W-phase PWM signal is low, the switching element Qw1 forming the W-phase upper arm is off and the switching element Qw2 forming the W-phase lower arm is on.

  As shown in FIG. 6, in the present embodiment, the control device 25 controls the output voltages of the three phases (U phase, V phase, W phase) output from the inverter circuit 24 to have the same polarity (all High polarities). The phase of the V-phase PWM signal is shifted so that the period of time (or low polarity) becomes shorter. Specifically, the waveform of the V-phase PWM signal after executing the phase shift process is 180 ° out of phase with the waveforms of the U-phase and W-phase PWM signals. Therefore, in the present embodiment, in the phase shift process, the control device 25 controls the V-phase PWM signal, which is one of the three-phase PWM signals generated according to the energization pattern determined in the energization pattern determination process. The phase of the waveform of is shifted by 180 ° with respect to the phases of the waveforms of the PWM signals of the U phase and the W phase which are the other phases.

  In FIG. 6, the waveform of the V-phase PWM signal before performing the phase shift process is indicated by a chain double-dashed line, and the waveform of the V-phase PWM signal after performing the phase shift process is indicated by a solid line. As shown in FIG. 6, as can be seen by comparing the waveforms of the three-phase PWM signals before performing the phase shift process with the respective waveforms of the three-phase PWM signals after performing the phase shift process, After the phase shift processing is executed, the period during which all the three-phase PWM signals are High or Low is short.

  The control device 25 outputs a three-phase PWM signal having a phase after the phase shift processing to the inverter circuit 24, and supplies a direct current to the motor 16 with the energization pattern determined in the energization pattern determination processing. A control program for controlling the inverter circuit 24 is stored in advance.

Next, the operation of this embodiment will be described.
As shown in FIG. 7, the control device 25 first estimates the temperature of the capacitor 32 based on the information regarding the temperature transmitted from the temperature sensor 34 in step S11. Next, in step S12, control device 25 determines whether or not the estimated temperature of capacitor 32 is equal to or lower than a predetermined temperature. When the control device 25 determines in step S12 that the temperature of the capacitor 32 is not lower than or equal to the predetermined temperature, the control device 25 proceeds to step S13 and controls the inverter circuit 24 so as to supply an alternating current to the motor 16. The normal control mode is set.

  On the other hand, when the control device 25 determines in step S12 that the temperature of the condenser 32 is equal to or lower than the predetermined temperature, the control device 25 proceeds to step S14, enters the warm-up control mode, and estimates the position θ of the rotor 18 in step S14. To do. Then, in step S15, the control device 25 executes an energization pattern determination process that determines an energization pattern for the motor 16 according to the position θ of the rotor 18. For example, when the estimated position θ of the rotor 18 is 30 °, the control device 25 determines the energization pattern in which the position θ of the rotor 18 is 0 ° by the energization pattern determination process.

  Next, the control device 25 executes the maximum allowable value determination process of calculating the maximum allowable motor current value in step S16. Further, in step S17, the control device 25 generates a three-phase PWM signal according to the energization pattern determined in the energization pattern determination process. For example, when the energization pattern determined by the energization pattern determination processing is the energization pattern in which the position θ of the rotor 18 is 0 °, the control device 25 controls the three phases for setting the position θ of the rotor 18 to 0 °. Generate a PWM signal.

  Then, in step S18, the control device 25 executes a phase shift process of shifting the phase of the PWM signal of one phase among the generated PWM signals of three phases. The control device 25 executes, for example, a phase shift process for shifting the phase of the V-phase PWM signal, and outputs a three-phase PWM signal having the phase after the phase shift process to the inverter circuit 24.

  FIG. 8 shows the current flow at the timing T1 in FIG. Timing T1 is a timing at which the U-phase PWM signal is High, the V-phase PWM signal is Low, and the W-phase PWM signal is switched from High to Low. As shown in FIG. 8, at timing T1, since the U-phase PWM signal is High, the switching element Qu1 forming the upper arm of the U phase is in the ON state and the switching element forming the lower arm of the U phase. Qu2 is off. Therefore, as indicated by an arrow R1a in FIG. 8, the current discharged from the capacitor 32 passes through the switching element Qu1 and flows to the motor 16 as the U-phase current Iu. Since the DC power supply 31 has an inductance component, the current from the DC power supply 31 continues to flow as the U-phase current Iu as indicated by an arrow R1b in FIG. At this time, in the energization pattern in which the position θ of the rotor 18 is 0 °, the relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw is Iu: Iv: Iw = + 1: -0.5:- The relationship is 0.5. Therefore, since the value of the current discharged from the capacitor 32 and flowing as the U-phase current Iu is the maximum, the value of the current discharged from the capacitor 32 is large. Therefore, the capacitor 32 generates heat and the capacitor 32 is warmed up.

  Further, at timing T1, since the V-phase PWM signal is Low, the switching element Qv1 forming the V-phase upper arm is off and the switching element Qv2 forming the V-phase lower arm is on. is there. Therefore, the V-phase current Iv passes through the switching element Qv2 and flows toward the DC power supply 31 and the capacitor 32, as indicated by an arrow R1c in FIG. Further, at timing T1, since the W-phase PWM signal is Low, the switching element Qw1 forming the W-phase upper arm is in the OFF state and the switching element Qw2 forming the W-phase lower arm is in the ON state. is there. Therefore, the W-phase current Iw passes through the switching element Qw2 and flows toward the DC power supply 31 and the capacitor 32 as shown by an arrow R1d in FIG.

  FIG. 9 shows the current flow at the timing T2 in FIG. Timing T2 is a timing when the W-phase PWM signal is Low, the U-phase PWM signal is switched from High to Low, and the V-phase PWM signal is switched from Low to High. As shown in FIG. 9, at timing T2, since the V-phase PWM signal is High, the switching element Qv1 forming the V-phase upper arm is in the ON state and the switching element forming the V-phase lower arm is on. Qv2 is off. Therefore, as shown by arrow R2a in FIG. 9, V-phase current Iv passes through switching element Qv1 and flows into capacitor 32 as a regenerative current. At this time, the current from the DC power supply 31 also flows into the capacitor 32, as indicated by the arrow R2b in FIG. As a result, the capacitor 32 is charged, the capacitor 32 generates heat, and the capacitor 32 is warmed up.

  At timing T2, since the U-phase PWM signal is Low, the switching element Qu1 that forms the upper arm of the U phase is off and the switching element Qu2 that forms the lower arm of the U phase is on. is there. Therefore, as shown by an arrow R2c in FIG. 9, a current flows from the DC power supply 31 and the capacitor 32 through the switching element Qu2 to the motor 16 as the U-phase current Iu. Further, since the W-phase PWM signal is low, the switching element Qw1 forming the W-phase upper arm is off and the switching element Qw2 forming the W-phase lower arm is on. Therefore, as shown by an arrow R2d in FIG. 9, the W-phase current Iw passes through the switching element Qw2 and flows toward the DC power supply 31 and the capacitor 32.

  FIG. 10 shows the current flow at the timing T3 in FIG. Timing T3 is timing at which a predetermined time has elapsed from timing T2 while maintaining the relationship between High and Low of the three-phase PWM signals at timing T2. As shown in FIG. 10, since the capacitor 32 is in the fully charged state at the timing T3 when a predetermined time has elapsed from the timing T2, the V-phase current Iv changes to the switching element Qv1 as indicated by an arrow R3a in FIG. And flows toward the DC power supply 31 without flowing into the capacitor 32 as a regenerative current.

  FIG. 11 shows the current flow at the timing T4 in FIG. Timing T4 is the timing when the V-phase PWM signal is High, the W-phase PWM signal is Low, and the U-phase PWM signal is switched from Low to High. As shown in FIG. 11, at timing T4, since the U-phase PWM signal is High, the switching element Qu1 forming the U-phase upper arm is in the ON state, and the switching element forming the U-phase lower arm is on. Qu2 is off. Therefore, as indicated by an arrow R4a in FIG. 11, the current discharged from the capacitor 32 passes through the switching element Qu1 and flows to the motor 16 as the U-phase current Iu.

  Further, at timing T4, since the V-phase PWM signal is High, the switching element Qv1 forming the V-phase upper arm is on and the switching element Qv2 forming the V-phase lower arm is off. is there. Therefore, as shown by the arrow R4b in FIG. 11, the V-phase current Iv passes through the switching element Qv1 and flows toward the capacitor 32 as a regenerative current. Therefore, the value of the current discharged from the capacitor 32 to the motor 16 side as the U-phase current Iu is a value obtained by subtracting the value of the V-phase current Iv flowing toward the capacitor 32 as the regenerative current. Since the DC power supply 31 has an inductance component, current continues to flow from the capacitor 32 toward the DC power supply 31 as indicated by an arrow R4c in FIG. Therefore, the capacitor 32 is also discharged to the DC power supply 31 side. As a result, the capacitor 32 generates heat and the capacitor 32 is warmed up.

  At timing T4, since the W-phase PWM signal is Low, the switching element Qw1 forming the W-phase upper arm is off and the switching element Qw2 forming the W-phase lower arm is on. is there. Therefore, the W-phase current Iw passes through the switching element Qw2 and flows toward the DC power supply 31 and the capacitor 32 as shown by an arrow R4d in FIG.

  FIG. 12 shows the current flow at the timing T5 in FIG. Timing T5 is a timing at which the U-phase PWM signal is High, the V-phase PWM signal is switched from High to Low, and the W-phase PWM signal is switched from Low to High. As shown in FIG. 12, at timing T5, since the U-phase PWM signal is High, the switching element Qu1 forming the U-phase upper arm is in the ON state and the switching element forming the U-phase lower arm is on. Qu2 is off. Therefore, as shown by arrow R5a in FIG. 12, the current discharged from capacitor 32 passes through switching element Qu1 and flows to motor 16 as U-phase current Iu.

  At timing T5, since the W-phase PWM signal is High, the switching element Qw1 that forms the upper arm of the W phase is on and the switching element Qw2 that forms the lower arm of the W phase is off. is there. Therefore, as shown by arrow R5b in FIG. 12, W-phase current Iw passes through switching element Qw1 and flows toward capacitor 32 as a regenerative current. Therefore, the value of the current discharged from the capacitor 32 to the motor 16 side as the U-phase current Iu is a value obtained by subtracting the value of the W-phase current Iw flowing toward the capacitor 32 as the regenerative current. Since the DC power supply 31 has an inductance component, current continues to flow from the capacitor 32 toward the DC power supply 31 as indicated by an arrow R5c in FIG. Therefore, the capacitor 32 is also discharged to the DC power supply 31 side. As a result, the capacitor 32 generates heat and the capacitor 32 is warmed up.

  At timing T5, since the V-phase PWM signal is Low, the switching element Qv1 forming the V-phase upper arm is off and the switching element Qv2 forming the V-phase lower arm is on. is there. Therefore, the V-phase current Iv passes through the switching element Qv2 and flows toward the DC power supply 31 and the capacitor 32, as indicated by an arrow R5d in FIG.

  FIG. 13 shows the current flow at the timing T6 in FIG. Timing T6 is timing when a predetermined time has elapsed from timing T5 while maintaining the relationship of High and Low of the three-phase PWM signals at timing T5. As shown in FIG. 13, at timing T6 when a predetermined time has elapsed from timing T5, the discharge from the capacitor 32 ends, and the current from the DC power supply 31 passes through the switching element Qu1 as indicated by an arrow R6a in FIG. Then, the U-phase current Iu flows to the motor 16. Then, the current flowing from the DC power supply 31 flows into the capacitor 32, and the capacitor 32 is charged. In this way, by repeating the current flow described in FIGS. 8 to 13, the condenser 32 is warmed up.

  As shown in FIG. 7, the controller 25 estimates the temperature of the condenser 32 in step S19 based on the information about the temperature transmitted from the temperature sensor 34. Then, in step S20, control device 25 determines whether or not the estimated temperature of capacitor 32 has exceeded a predetermined temperature. When the control device 25 determines in step S20 that the temperature of the capacitor 32 does not exceed the predetermined temperature, the control device 25 proceeds to step S16. On the other hand, when the control device 25 determines in step S20 that the temperature of the capacitor 32 has exceeded the predetermined temperature, the control device 25 proceeds to step S13 and switches from the warm-up control mode to the normal control mode.

  FIG. 14 shows, as a comparative example, a change in current flowing through the motor 16 in the energization pattern in which the position θ of the rotor 18 is 0 ° when the control device 25 does not execute the phase shift process, and the three-phase The relationship between changes in the PWM signal and changes in the current flow to the capacitor 32 is shown. As shown in FIG. 14, in the comparative example, since the control device 25 does not execute the phase shift process, the period in which all the three-phase PWM signals are High or Low compared to the case where the phase shift process is executed. Is getting longer.

  FIG. 15 shows the current flow at the timing T11 in FIG. Timing T11 is a timing when the U-phase PWM signal is High and the V-phase PWM signal and the W-phase PWM signal are switched from High to Low. As shown in FIG. 15, at timing T11, since the U-phase PWM signal is High, the switching element Qu1 forming the U-phase upper arm is in the ON state, and the switching element forming the U-phase lower arm is on. Qu2 is off. Therefore, as indicated by an arrow R11a in FIG. 15, the current discharged from the capacitor 32 passes through the switching element Qu1 and flows to the motor 16 as the U-phase current Iu. At this time, in the energization pattern in which the position θ of the rotor 18 is 0 °, the relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw is Iu: Iv: Iw = + 1: -0.5:- The relationship is 0.5. Therefore, since the value of the current discharged from the capacitor 32 and flowing as the U-phase current Iu is the maximum, the value of the current discharged from the capacitor 32 is large. Therefore, the capacitor 32 generates heat and the capacitor 32 is warmed up.

  At timing T11, since the V-phase PWM signal is Low, the switching element Qv1 forming the V-phase upper arm is off and the switching element Qv2 forming the V-phase lower arm is on. is there. Therefore, the V-phase current Iv passes through the switching element Qv2 and flows toward the DC power supply 31 and the capacitor 32, as indicated by an arrow R11b in FIG. Further, at timing T11, since the W-phase PWM signal is Low, the switching element Qw1 forming the W-phase upper arm is in the OFF state and the switching element Qw2 forming the W-phase lower arm is in the ON state. is there. Therefore, W-phase current Iw passes through switching element Qw2 and flows toward DC power supply 31 and capacitor 32, as indicated by arrow R11c in FIG.

  FIG. 16 shows the current flow at the timing T12 in FIG. Timing T12 is a timing when the V-phase PWM signal and the W-phase PWM signal are Low and the W-phase PWM signal is switched from High to Low. As shown in FIG. 16, at timing T12, since the PWM signals of the three phases are all Low, each of the switching elements Qu1, Qv1, Qw1 forming the upper arm of each phase is in the off state, and the The switching elements Qu2, Qv2, Qw2 forming the lower arm are in the ON state. Therefore, the V-phase current Iv passing through the switching element Qv2 as shown by the arrow R12a in FIG. 16 and the W-phase current Iw passing through the switching element Qw2 as shown by the arrow R12b in FIG. As indicated by an arrow R12c, it passes through the switching element Qu2 and flows to the motor 16 as a U-phase current Iu. Further, as shown by an arrow R12d in FIG. 16, a current from the DC power supply 31 flows into the capacitor 32. As a result, the capacitor 32 is charged, the capacitor 32 generates heat, and the capacitor 32 is warmed up.

  FIG. 17 shows the current flow at the timing T13 in FIG. Timing T13 is timing when a predetermined time has elapsed from timing T12 while maintaining the relationship of High and Low of the three-phase PWM signals at timing T12. As shown in FIG. 17, at timing T13 when a predetermined time has elapsed from timing T12, the capacitor 32 is in a fully charged state, and no current flows from the DC power supply 31 to the capacitor 32.

  FIG. 18 shows the current flow at the timing T14 in FIG. Timing T14 is a timing when the V-phase PWM signal and the W-phase PWM signal are Low, and the U-phase PWM signal is switched from Low to High. As shown in FIG. 18, at timing T14, since the U-phase PWM signal is High, the switching element Qu1 forming the U-phase upper arm is in the ON state, and the switching element forming the U-phase lower arm is on. Qu2 is off. Therefore, as indicated by an arrow R13a in FIG. 18, the current discharged from the capacitor 32 passes through the switching element Qu1 and flows to the motor 16 as the U-phase current Iu. Therefore, the capacitor 32 generates heat and the capacitor 32 is warmed up.

  At timing T14, since the V-phase PWM signal is Low, the switching element Qv1 forming the V-phase upper arm is off and the switching element Qv2 forming the V-phase lower arm is on. is there. Therefore, the V-phase current Iv passes through the switching element Qv2 and flows toward the DC power supply 31 and the capacitor 32, as indicated by an arrow R13b in FIG. Further, at timing T14, since the W-phase PWM signal is Low, the switching element Qw1 forming the W-phase upper arm is in the OFF state and the switching element Qw2 forming the W-phase lower arm is in the ON state. is there. Therefore, W-phase current Iw passes through switching element Qw2 and flows toward DC power supply 31 and capacitor 32, as indicated by arrow R13c in FIG.

  FIG. 19 shows the current flow at timing T15 in FIG. Timing T15 is a timing when the U-phase PWM signal is High and the V-phase PWM signal and the W-phase PWM signal are switched from Low to High. As shown in FIG. 19, at timing T15, since the PWM signals of the three phases are all High, each of the switching elements Qu1, Qv1, Qw1 forming the upper arm of each phase is in the ON state and the PWM signal of each phase is The switching elements Qu2, Qv2, Qw2 forming the lower arm are off. Therefore, the V-phase current Iv passing through the switching element Qv1 as shown by the arrow R14a in FIG. 19 and the W-phase current Iw passing through the switching element Qw1 as shown by the arrow R14b in FIG. As indicated by an arrow R14c, it passes through the switching element Qu1 and flows to the motor 16 as a U-phase current Iu. Further, as shown by an arrow R14d in FIG. 19, a current from the DC power supply 31 flows into the capacitor 32. As a result, the capacitor 32 is charged, the capacitor 32 generates heat, and the capacitor 32 is warmed up.

  FIG. 20 shows the current flow at timing T16 in FIG. Timing T16 is timing when a predetermined time has elapsed from timing T15 while maintaining the relationship of High and Low of the three-phase PWM signals at timing T15. As shown in FIG. 20, at timing T16 when a predetermined time has elapsed from timing T15, the capacitor 32 is in a fully charged state, and no current flows from the DC power supply 31 to the capacitor 32.

  In the comparative example described with reference to FIGS. 14 to 20, between the timing T12 and the timing T13, and between the timing T15 and the timing T16, the PWM signals of the three phases are all High or Low, and During the period, none of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw contributes to the charging / discharging of the capacitor 32. As in the comparative example described in FIGS. 14 to 20, when the phase shift process is not executed, the U-phase current Iu and the V-phase current Iv are long because the PWM signals of the three phases are all High or Low. , And the W-phase current Iw do not contribute to the charging / discharging of the capacitor 32, the period becomes longer. Therefore, as in the comparative example described in FIGS. 14 to 20, when the phase shift process is not executed, the charge / discharge amount of the capacitor 32 is small and the capacitor 32 is hard to warm.

  On the other hand, in the present embodiment, the control device 25 executes the phase shift process in the warm-up control mode so that the V-phase current Iv passes through the switching element Qv1 between the timing T2 and the timing T3. Then, it flows into the capacitor 32 as a regenerative current. Therefore, as compared with the case where the phase shift process is not executed, the charge / discharge amount of the capacitor 32 becomes large and the capacitor 32 warms up early.

  In FIG. 21, as a comparative example, for example, the change in the current flowing through the motor 16 when the position θ of the rotor 18 is 30 ° and the change in the three-phase PWM signal, and the current flow through the capacitor 32 are shown. It shows the relationship of change. In this comparative example, as shown in FIG. 21, the polarities of the output voltages of the three phases (U phase, V phase, W phase) output from the inverter circuit 24 are all the same (all are High polarity or Low polarity). The phase of the V-phase PWM signal is shifted so that a certain period is shortened. Specifically, the waveform of the V-phase PWM signal after executing the phase shift process is 180 ° out of phase with the waveforms of the U-phase and W-phase PWM signals.

  FIG. 22 shows the current flow at the timing T21 in FIG. Timing T21 is a timing at which the U-phase PWM signal is High, the V-phase PWM signal is Low, and the W-phase PWM signal is switched from High to Low. As shown in FIG. 22, at timing T21, since the U-phase PWM signal is High, the switching element Qu1 that forms the upper arm of the U phase is in the on state, and the switching element that forms the lower arm of the U phase. Qu2 is off. Therefore, as shown by arrow R21a in FIG. 22, the current discharged from capacitor 32 passes through switching element Qu1 and flows to motor 16 as U-phase current Iu. Therefore, the capacitor 32 generates heat and the capacitor 32 is warmed up.

  At timing T21, since the V-phase PWM signal is Low, the switching element Qv1 forming the V-phase upper arm is off and the switching element Qv2 forming the V-phase lower arm is on. is there. Therefore, the V-phase current Iv passes through the switching element Qv2 and flows toward the DC power supply 31 and the capacitor 32, as indicated by an arrow R21b in FIG. Further, at timing T21, since the W-phase PWM signal is Low, the switching element Qw1 forming the W-phase upper arm is off and the switching element Qw2 forming the W-phase lower arm is on. is there. Therefore, the W-phase current Iw passes through the switching element Qw2 and flows toward the DC power supply 31 and the capacitor 32, as indicated by an arrow R21c in FIG.

  FIG. 23 shows the current flow at the timing T22 in FIG. Timing T22 is a timing at which the U-phase PWM signal is High, the W-phase PWM signal is Low, and the V-phase PWM signal is switched from Low to High. As shown in FIG. 23, at timing T22, since the U-phase PWM signal is High, the switching element Qu1 forming the U-phase upper arm is in the ON state, and the switching element forming the U-phase lower arm is on. Qu2 is off. Therefore, as shown by arrow R22a in FIG. 23, the current discharged from capacitor 32 passes through switching element Qu1 and flows to motor 16 as U-phase current Iu.

  At timing T22, since the V-phase PWM signal is High, the switching element Qv1 forming the V-phase upper arm is on and the switching element Qv2 forming the V-phase lower arm is off. is there. Therefore, as shown by an arrow R22b in FIG. 23, the V-phase current Iv passes through the switching element Qv1 and flows toward the capacitor 32 as a regenerative current. Therefore, the value of the current discharged from the capacitor 32 as the U-phase current Iu to the motor 16 side is a value obtained by subtracting the value of the V-phase current flowing toward the capacitor 32 as the regenerative current. As a result, the capacitor 32 generates heat and the capacitor 32 is warmed up.

  At timing T22, since the W-phase PWM signal is Low, the switching element Qw1 forming the W-phase upper arm is off and the switching element Qw2 forming the W-phase lower arm is on. is there. Therefore, W-phase current Iw passes through switching element Qw2 and flows toward DC power supply 31 and capacitor 32, as indicated by arrow R22c in FIG.

  FIG. 24 shows the current flow at timing T23 in FIG. Timing T23 is the timing when the V-phase PWM signal is High, the W-phase PWM signal is Low, and the U-phase PWM signal is switched from High to Low. As shown in FIG. 24, at timing T23, since the V-phase PWM signal is High, the switching element Qv1 forming the V-phase upper arm is in the ON state, and the switching element forming the V-phase lower arm is on. Qv2 is off. Therefore, as shown by arrow R23a in FIG. 24, V-phase current Iv passes through switching element Qv1 and flows into capacitor 32 as a regenerative current. As a result, the capacitor 32 is charged, the capacitor 32 generates heat, and the capacitor 32 is warmed up.

  At timing T23, since the U-phase PWM signal is Low, the switching element Qu1 forming the U-phase upper arm is off and the switching element Qu2 forming the U-phase lower arm is on. is there. Therefore, as shown by an arrow R23b in FIG. 24, a current flows from the DC power supply 31 and the capacitor 32 through the switching element Qu2 to the motor 16 as the U-phase current Iu. Further, since the W-phase PWM signal is low, the switching element Qw1 forming the W-phase upper arm is off and the switching element Qw2 forming the W-phase lower arm is on. Therefore, as shown by arrow R23c in FIG. 24, W-phase current Iw passes through switching element Qw2 and flows toward DC power supply 31 and capacitor 32.

  21 to 24, in the energization pattern in which the position θ of the rotor 18 is 30 °, the relationship between the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw is Iu: Iv. : Iw = + √3 / 2: 0: −√3 / 2. Therefore, in this comparative example, the phase of the V-phase PWM signal having the smallest current value is shifted. In this case, at timing T23, the V-phase current Iv passes through the switching element Qv1 and flows into the capacitor 32 as a regenerative current. However, since the value of the V-phase current Iv is the minimum, the V-phase current Iv flows to the capacitor 32 as a regenerative current. The current flowing in is small. Therefore, the heat generated by the capacitor 32 is small, and it is difficult for the capacitor 32 to warm up. As described above, the inventors of the present invention generate a small amount of current when flowing as a regenerative current from the coil 19 having a phase shifted from the PWM signal having the minimum current value to the capacitor 32. It has been found that the capacitor 32 is small and it is difficult to heat the capacitor 32.

  Therefore, in the present embodiment, even if the estimated position θ of the rotor 18 is a position where the value of the current of any one of the phases is the minimum, such as 30 °, the control device 25 does not energize. By executing the pattern determination process, the energization pattern of the motor 16 becomes the energization pattern of the position θ of the rotor 18 in which only one of the phases is always the maximum allowable motor current value. Further, the control device 25 executes a phase shift process of shifting the phase of the PWM signal of one phase among the PWM signals of three phases generated according to the energization pattern determined by the energization pattern determination process. Therefore, of the three-phase PWM signals generated at the position θ of the rotor 18 where the current value is the minimum, the phase of the PWM signal of the phase where the current value is the minimum is not shifted. Then, the control device 25 outputs a three-phase PWM signal having a phase after the phase shift processing to the inverter circuit 24 and supplies a direct current to the motor 16 with the energization pattern determined in the energization pattern determination processing. .. For this reason, the value of the current flowing from the coil 19 to the capacitor 32 as a regenerative current becomes large, so that the capacitor 32 is easily warmed. Therefore, the condenser 32 is warmed up early regardless of the position θ of the rotor 18.

In the above embodiment, the following effects can be obtained.
(1) When the estimated temperature of the capacitor 32 is equal to or lower than the predetermined temperature, the control device 25 determines the energization pattern of the motor 16 according to the estimated position θ of the rotor 18 by the coil of each phase. The energization pattern determination process is performed to determine any one of the six patterns in which only one of the currents flowing to 19 is positively or negatively always the maximum allowable motor current value. Further, the control device 25 is generated according to the maximum allowable value determination process of determining the maximum allowable motor current value based on the estimated temperature information of the capacitor 32 and the energization pattern determined by the energization pattern determination process. Phase shift processing for shifting the phase of the PWM signal of one phase among the PWM signals of three phases is executed. The phase ranges of the energization patterns are the same. According to this, of the three-phase PWM signals generated at the position θ of the rotor 18 where the current value is the minimum, the phase of the PWM signal of the phase where the current value is the minimum can be shifted. There is no. Therefore, the value of the current flowing from the coil 19 to the capacitor 32 as a regenerative current becomes large, and the capacitor 32 is easily warmed. As a result, the capacitor 32 can be warmed up early regardless of the position θ of the rotor 18.

  (2) In the energization pattern determination process, the control device 25 determines the energization pattern that is the closest to the estimated position θ of the rotor 18 among the six patterns. According to this, when the control device 25 controls the inverter circuit 24 so as to supply the direct current to the motor 16 with the energization pattern determined by the energization pattern determination process, the rotor 18 rotates largely. It can be suppressed. Therefore, it is possible to suppress the generation of abnormal noise from the compression unit 15 due to the large rotation of the rotor 18.

  (3) In the phase shift process, the control device 25 controls the phase of the waveform of the V-phase PWM signal, which is one of the three-phase PWM signals generated according to the energization pattern determined in the energization pattern determination process. Is shifted by 180 ° with respect to the phases of the waveforms of the PWM signals of the other phases, U phase and W phase. According to this, the time during which the current flows through the capacitor 32 can be lengthened, so that the capacitor 32 is more easily warmed. Therefore, the capacitor 32 can be warmed up earlier.

  (4) When the estimated temperature of the capacitor 32 is equal to or lower than the predetermined temperature, the capacitor 32 can be warmed early, so that the control device 25 can control the inverter circuit 24 in the normal control mode. It is possible to shorten the time until it becomes possible.

  The above-described embodiment can be modified and implemented as follows. The above-described embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

  In the embodiment, the control device 25 may determine the energization pattern other than the energization pattern closest to the estimated position θ of the rotor 18 among the six patterns in the energization pattern determination process. That is, when the estimated position θ of the rotor 18 is 30 °, the control device 25 does not determine the energization pattern in which the position θ of the rotor 18 is 0 ° by the energization pattern determination process, but instead, for example, Alternatively, the energization pattern may be determined such that the position θ of the rotor 18 is 120 °.

  In the embodiment, in the warm-up control mode, the control device 25, when the estimated position θ of the rotor 18 is, for example, 330 ° ≦ θ ≦ 360 ° and 0 ° ≦ θ <30 °, the energization pattern. By the determination processing, the energization pattern may be determined such that the position θ of the rotor 18 becomes 0 °. In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 30 ° ≦ θ <90 °, the controller 25 sets the position θ of the rotor 18 to 60 ° by the energization pattern determination process. The energization pattern may be determined. In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 90 ° ≦ θ <150 °, the control device 25 sets the position θ of the rotor 18 to 120 ° by the energization pattern determination process. The energization pattern may be determined. In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 150 ° ≦ θ <210 °, the controller 25 determines the position θ of the rotor 18 to be 180 ° by the energization pattern determination process. The energization pattern may be determined. In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 210 ° ≦ θ <270 °, the controller 25 determines the position θ of the rotor 18 to be 240 ° by the energization pattern determination process. The energization pattern may be determined. In the warm-up control mode, when the estimated position θ of the rotor 18 is, for example, 270 ° ≦ θ <330 °, the controller 25 determines the position θ of the rotor 18 to be 300 ° by the energization pattern determination process. The energization pattern may be determined.

  In the embodiment, the control device 25 may shift the phase of the V-phase PWM signal instead of shifting the phase of the V-phase PWM signal in the phase shift process. In the phase shift process, the control device 25 may shift the phase of the W-phase PWM signal instead of shifting the phase of the V-phase PWM signal.

  In the embodiment, the degree of shifting the phase of the waveform of the V-phase PWM signal with respect to the phase of the waveforms of the U-phase and W-phase PWM signals in the phase shift process is not limited to 180 °. In short, in the phase shift processing, the period in which all the polarities of the output voltages of the three phases (U phase, V phase, W phase) output from the inverter circuit 24 are all the same (all are High polarity or Low polarity) is short. Therefore, the phase of the waveform of the V-phase PWM signal may be shifted from the phase of the waveforms of the U-phase and W-phase PWM signals.

○ In the embodiment, the phase range of each energization pattern may not be 60 °. The point is that the phase ranges of the respective energization patterns need only be approximately equal.
In the embodiment, the capacitor 32 may be, for example, a film capacitor.

  In the embodiment, the temperature sensor 34 may detect (estimate) the temperature of the capacitor 32 instead of detecting the temperature of the substrate on which the capacitor 32 is mounted. In this case, the controller 25 does not have to previously store a temperature estimation program for estimating the temperature of the capacitor 32 based on the information about the temperature transmitted from the temperature sensor 34, and only the temperature sensor 34 has the capacitor 32. It functions as a temperature estimation unit that estimates the temperature of.

  In the embodiment, the position sensorless control for controlling the rotation of the motor 16 is performed based on the position θ of the rotor 18 estimated by the control device 25. However, the present invention is not limited to this, and the control device 25 A rotation speed sensor such as a resolver may be used to estimate the position θ of the rotor 18 and control the rotation of the motor 16.

  In the embodiment, the electric compressor 10 may have a configuration in which the inverter circuit 24 is arranged outside the housing 11 in the radial direction of the rotary shaft 14, for example. In short, the compression unit 15, the motor 16, and the inverter circuit 24 do not have to be arranged in this order in the rotation axis direction of the rotation shaft 14.

  In the embodiment, the electric compressor 10 constitutes the vehicle air conditioner 21, but the present invention is not limited to this. For example, the electric compressor 10 is mounted on a fuel cell vehicle and is supplied to the fuel cell. The air as a fluid may be compressed by the compression unit 15.

  Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 ... switching element, 10 ... electric compressor, 15 ... compression section, 16 ... motor, 18 ... rotor, 19 ... coil, 24 ... inverter circuit, 25 ... control section A controller that functions as a rotor position estimation unit and a temperature estimation unit, 31 ... DC power supply, 32 ... Capacitor, 34 ... Temperature sensor that constitutes a temperature estimation unit.

Claims (3)

A compression unit for compressing a fluid,
A motor for driving the compression unit,
An inverter circuit that has a switching element that performs a switching operation to drive the motor, and an output side is connected to coils of each phase of the motor,
A capacitor provided on the input side of the inverter circuit and connected in parallel to the DC power supply,
A control unit that outputs a three-phase PWM signal to the inverter circuit to control the inverter circuit;
A temperature estimating unit for estimating the temperature of the capacitor,
A rotor position estimation unit that estimates the position of the rotor of the motor,
The control unit is
When the temperature of the capacitor estimated by the temperature estimation unit is equal to or lower than a predetermined temperature, the energization pattern to the motor is set to each of the power distribution patterns according to the position of the rotor estimated by the rotor position estimation unit. Energization pattern determination processing in which only one of the currents flowing in the phase coils is positively or negatively determined to be one of the six patterns that is always the maximum allowable value,
A maximum allowable value determination process of determining the maximum allowable value based on information from the temperature estimation unit,
A phase shift process of shifting the phase of a PWM signal of one phase among the PWM signals of three phases generated according to the energization pattern determined by the energization pattern determination process,
The electric compressor in which the phase ranges of the energization patterns are the same.   The motor according to claim 1, wherein the control unit determines, in the energization pattern determination process, the energization pattern that is the closest to the position of the rotor estimated by the rotor position estimation unit among the six patterns. Compressor.   In the phase shift process, the control unit sets the phase of one phase PWM signal of the three-phase PWM signals generated according to the energization pattern determined in the energization pattern determination process to the other phase. The electric compressor according to claim 1 or 2, wherein the phase of the PWM signal is shifted by 180 °.