Motor-driven compressor

Abstract

Motor-driven compressor (10), with an electric motor (16) including a rotor (51), a housing (11) including a suction port (11a) which sucks in a fluid, a compression unit (15) driven by the electric motor (16), the compression unit (15) compressing an inlet fluid, which is the fluid sucked in through the suction port (11a), and discharging a compressed fluid, which is the compressed inlet fluid, a drive circuit (55) which drives the electric motor (16), and a control device (60) which controls the drive circuit (55) to control rotation of the rotor (51), wherein the compression unit (15) has a fixed roller (31) attached to the housing (11), a movable roller (32) engaged with the fixed roller (31) and adapted to orbit the fixed roller (31), and a compression chamber (33) defined by the fixed roller (31) and the movable roller (32), wherein, when the rotor (51) rotates in a predetermined forward direction, the movable roller (32) orbits in the forward direction, and the compression unit (15) thereby compresses the inlet fluid sucked into the compression chamber (33), wherein the motor-driven compressor (10) further comprises an injection port (43) which sucks an intermediate pressure fluid into the compression chamber (33), the intermediate pressure fluid having a pressure higher than that of the inlet fluid and lower than that of the compressed fluid, wherein the control device (60) comprises a deceleration control device that performs a deceleration control that decelerates the rotor (51) during a first period in response to rotating the rotor (51) in a direction opposite to the forward direction, and a continuation control means which performs a continuation control which continues the rotation of the rotor (51) during a second period of time which is longer than the first period of time after the deceleration control is performed, and wherein a fluctuation difference of a rotation frequency of the rotor (51) during the continuation control is less than a deceleration rotation frequency difference, which is a difference between a rotation frequency of the rotor (51) when the deceleration control is started and a rotation frequency of the rotor (51) when the deceleration control is ended.

Description

Background of the invention

[0001] The present invention relates to a motor-driven compressor.

[0002] Japanese Laid-Open Patent Publication No. JP 2003-120555 A discloses an example of a motor-driven compressor including a compression unit having a fixed roller and a movable roller capable of orbiting the fixed roller, and an electric motor having a rotor that causes the movable roller to orbit. The motor-driven compressor includes a compression chamber defined by the fixed roller and the movable roller, which draws in an intake fluid. The orbiting of the movable roller compresses the intake fluid in the compression chamber and discharges the compressed fluid.

[0003] Japanese Laid-Open Patent Publication No. JP 2003-120555 A also describes a motor-driven compressor that includes an injection port that sucks intermediate-pressure fluid at a higher pressure than the inlet fluid into the compression chamber, and describes an air conditioner including the motor-driven compressor. The air conditioner includes, for example, an injection pipe connected to the injection port, and a gas-liquid separation element connected to the inlet pipe. The intermediate-pressure fluid flows from the gas-liquid separation element and into the compression chamber through the injection pipe and the injection port. This increases the flow rate of the fluid flowing into the compression chamber.

[0004] When the motor-driven compressor, which is configured to draw the intermediate pressure fluid into the compression chamber as described above, is deactivated, the remaining intermediate pressure fluid in the injection tube may flow into the compression chamber through the injection port. This may result in reverse rotation activity, in which the movable roller orbits in a direction opposite to the forward direction, reversing the rotation of the rotor. In this situation, noise and vibration tend to increase when the rotation frequency (rotation speed) of the rotor is high.

[0005] To stop the rotor immediately, the electric motor may, for example, be subject to a forced deactivation control that forcibly stops the rotor's reverse rotation. In this case, the intermediate pressure fluid may remain in the injection tube. The intermediate pressure fluid may cause reverse rotation recurrence, in which, after the rotor's rotation has stopped, the rotor rotates backward again. This reverse rotation recurrence may, for example, interfere with the activation of the engine-driven compressor.

[0006] Further prior art can be found in JP 5 768 863 B2, which discloses an electric compressor. A control computer issues a stop command to stop the rotation of a rotor and decides the rotation state of the rotor based on a voltage detected by a voltage detection part. Based on the decision, it performs start preparation control to issue a lock command to electrically stop the rotation of the rotor.

[0007] An electric compressor controller and a refrigeration cycle device are known from DE 11 2016 003 491 T5. The controller, which controls an electric compressor mounted on a vehicle and constructing a two-stage compression refrigeration cycle device, has a deceleration section, an operation stop section, and a restart section. The deceleration section reduces a rotational speed of an electric motor by controlling an alternating current output to the electric motor when a two-stage operation mode in which an intermediate-pressure refrigerant flows into the electric compressor from an intermediate-pressure port is performed and an operation stop request for stopping the electric compressor is made. The operation stop section stops the electric motor after the deceleration section reduces the rotational speed of the electric motor.The restart section restarts the electric compressor when the operation stop request is released after the operation stop section stops the electric compressor.

[0008] JP H11 - 164 584 A further shows a motor control, and US 2012 / 0 194 111 A1 shows an inverter unit. Summary of the invention

[0009] It is an object of the present invention to provide a motor-driven compressor that limits the occurrence of reverse rotation recurrence activities while limiting noise and vibration.

[0010] To solve the above problem, an engine-driven compressor includes an electric motor including a rotor, a housing including an intake port that sucks in a fluid, a compression unit driven by the electric motor, a drive circuit that drives the electric motor, and a control device that controls the drive circuit to control the rotation of the rotor. The compression unit compresses an inlet fluid, which is the fluid sucked in from the intake port, and discharges a compressed fluid, which is the compressed inlet fluid. The compression unit includes a fixed scroll that is attached to the housing, a movable scroll that engages with the fixed scroll and is configured to orbit around the fixed scroll, and a compression chamber defined by the fixed scroll and the movable scroll.When the rotor rotates in a predetermined forward direction, the movable roller orbits in the forward direction, and the compression unit thereby compresses the intake fluid drawn into the compression chamber. The motor-driven compressor further includes an injection port that draws an intermediate pressure fluid into the compression chamber. The intermediate pressure fluid has a pressure higher than that of the intake fluid and lower than that of the compressed fluid.The control device includes a deceleration control device that performs deceleration control that decelerates the rotor during a first period in response to the rotor rotating in a direction opposite to the forward direction, and a continuation control device that performs continuation control that continues the rotation of the rotor during a second period longer than the first period after the deceleration control is performed. A fluctuation difference of a rotation frequency of the rotor during the continuation control is less than a deceleration rotation frequency difference, which is a difference between a rotation frequency of the rotor when the deceleration control is started and a rotation frequency of the rotor when the deceleration control is ended.

[0011] Further aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, which illustrate by way of example the principles of the invention. Short description of the drawings

[0012] The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which Fig. 1 is a schematic cross-sectional view of a motor-driven compressor, Fig. 2 a cross-sectional view of a compression unit of the Fig. 1 shown motor-driven compressor, Fig. 3 is a schematic diagram of a vehicle air conditioning system, Fig. 4 is a circuit diagram showing the electrical configuration of an inverter, Fig. 5 is a timing diagram showing switching elements of a lower arm in a single-phase pattern, in which (a) shows activation and deactivation of a switching element of a lower u-phase arm, (b) shows activation and deactivation of a switching element of a lower v-phase arm, and (c) shows activation and deactivation of a switching element of a lower w-phase arm, Fig. 6 is a schematic graph showing each phase current when a rotor rotates in a forward direction, Fig. 7 is a schematic graph showing each phase current when the rotor rotates in a direction opposite to the forward direction, Fig. 8 is a flowchart of a reverse rotation control method, Fig. 9 is a timing diagram showing the switching elements of a lower arm in a two-phase pattern, in which (a) shows activation and deactivation of the switching element of a lower u-phase arm, (b) shows activation and deactivation of the switching element of a lower v-phase arm, and (c) shows activation and deactivation of the switching element of a lower W-phase arm, and Fig. Figure 10 is a graph showing changes in the rotation frequency of the rotor following deactivation. Detailed description of the preferred embodiments

[0013] An embodiment of a motor-driven compressor will now be described.

[0014] As in Fig. 1, a motor-driven compressor 10 comprises a housing 11 provided with a suction port 11a that sucks in a fluid and with an outlet 11b that discharges the fluid. The housing is tubular as a whole. In particular, the housing 11 comprises a first part 12 and a second part 13, each of which is tubular and has a closed end and an open end. The first part 12 and the second part 13 are coupled to each other with the open ends opposite each other. The suction port 11a is arranged at a side wall 12a of the first part 12, in particular at a portion of the side wall 12a of the first part that is adjacent to a closed end 12b of the first part 12. The outlet 11b is arranged at a closed end 13a of the second part 13.

[0015] The motor-driven compressor 10 includes a rotating shaft 14, a compression unit 15 that draws the fluid sucked from the suction port 11a, i.e., the intake fluid, and discharges the fluid from the outlet 11b, and an electric motor 16 that drives the compression unit 15. The rotating shaft 14, the compression unit 15, and the electric motor 16 are housed in the casing 11. The electric motor 16 is disposed in the casing 11 on a side corresponding to the suction port 11a. The compression unit 15 is disposed in the casing 11 on a side corresponding to the outlet 11b.

[0016] The rotating shaft 14 is rotatably housed in the housing 11. Specifically, the housing 11 houses a shaft support member 21 that rotatably supports the rotating shaft 14. The shaft support member 21 is fixed to the housing 11, for example, at a position between the compression unit 15 and the electric motor 16. The shaft support member 21 is provided with an insertion hole 23 around which a first bearing 22 is arranged. The rotating shaft 14 can be inserted through the insertion hole 23. The shaft support member 21 faces the closed end 12b of the first part 12. A tubular hub 24 protrudes from the closed end 12b. A second bearing 25 is arranged on an inner side of the hub 24. The rotating shaft 14 is rotatably supported by the first bearing 22 and the second bearing 25.

[0017] The compression unit 14 comprises a fixed roller 31 fixed to the housing 11 and a movable roller 32 capable of orbiting the fixed roller 31.

[0018] The fixed roller 31 includes a disc-shaped fixed base plate 31a coaxial with the rotating shaft 14 and a fixed spiral wall 31b protruding from the fixed base plate 31a. Similarly, the movable roller 32 includes a disc-shaped movable base plate 32a opposed to the fixed base plate 31a and a movable spiral wall 32b protruding from the movable base plate 32a toward the fixed base plate 31a.

[0019] As in Fig. 1 and Fig. 2, the fixed roller 31 and the movable roller 32 are engaged with each other. Specifically, the fixed spiral wall 31b and the movable spiral wall 32b are engaged with each other, with the fixed spiral wall 31b including a distal surface in contact with the movable base plate 32a, and the movable spiral wall 32b including a distal surface in contact with the fixed base plate 31a. The fixed roller 31 and the movable roller 32 define a compression chamber 33. As shown in Fig. 1, the shaft support member 21 includes an inlet passage 34 that draws the inlet fluid into the compression chamber 33.

[0020] The movable roller 32 is configured to orbit according to the rotation of the rotating shaft 14. Specifically, the rotating shaft 14 partially protrudes through the insertion hole 23 of the shaft support member 21 toward the compression unit 15. The rotating shaft 14 includes an end surface facing the compression unit 15. An eccentric shaft 35 is disposed at a portion of the end surface that is eccentric with respect to an axis L of the rotating shaft 14. A sleeve 36 is disposed on the eccentric shaft 35. The sleeve 36 is coupled to the movable roller 32 (specifically, the movable base plate 32a) via the bearing 37.

[0021] The motor-driven compressor 10 includes a rotation-limiting section 38 that limits the rotation of the movable roller 32 while enabling the (circular) movement of the movable roller 32. The motor-driven compressor 10 includes a plurality of rotation-limiting sections 38.

[0022] With this structure, when the rotating shaft 14 rotates in a predetermined forward direction, the movable roller 32 orbits in the forward direction. Specifically, the movable roller 32 orbits in the forward direction around the axis of the fixed roller 31 (i.e., axis L of the rotating shaft 14). This reduces the volume of the compression chamber 33 and compresses the intake fluid that has been sucked into the compression chamber 33 through the intake passage 34. The compressed intake fluid, i.e., the compressed fluid, is discharged from a discharge port 41 of the fixed base plate 31a and then the outlet 11b. The forward direction can also be referred to as the direction in which the fluid is compressed in a normal manner.

[0023] As in Fig. 1, a discharge valve 42 is arranged on the fixed base plate 31a to cover the discharge port 41. The compressed fluid compressed in the compression chamber 33 pushes the discharge valve 42 aside and is discharged from the discharge port 41.

[0024] As in Fig. 1 and Fig. 2, the fixed base plate 31a includes injection ports 43 each in addition to the discharge port 41. The fixed base plate 31a includes, for example, a plurality of injection pipe ports 43, specifically, two injection ports 43. The injection ports 43 are arranged on a radially outer side of the discharge port 41 in the fixed base plate 31a. The injection ports 43 are connected to an injection pipe 119. The connected article of the injection pipe 119 will be described below.

[0025] The electric motor 16 rotates the rotary shaft 14 to drive the rotating roller 32. As shown in Fig. 1, the electric motor 16 includes a rotor 51 that rotates integrally with the rotating shaft 14 and a stator 52 that surrounds the rotor 51. The rotor 51 is coupled to the rotating shaft 14. The rotor 51 includes a permanent magnet (not shown). The stator 52 is connected to an inner surface of the housing 11 (specifically, the first part 12). The stator 52 includes a stator core 53 radially opposed to the tubular rotor 51 and a coil 54 wound around the stator core 53.

[0026] The motor-driven compressor 10 includes an inverter 55 that acts as a drive circuit that drives the electric motor 16. The inverter 55 is housed in the housing 11, specifically in a tubular cover member 56 coupled to the closed end 12b of the first part 12. The inverter 55 is electrically connected to the coil 54.

[0027] In the present embodiment, the motor-driven compressor 10 is installed in a vehicle and used with a vehicle air conditioner 100. Therefore, in the present embodiment, the fluid compressed by the motor-driven compressor 10 is a refrigerant. The vehicle air conditioner 100 will now be described in detail.

[0028] As in Fig. 3, the vehicle air conditioner 100 includes a pipe switching valve 101, a first heat exchanger 102, a second heat exchanger 103, a first expansion valve 104, a second expansion valve 105, and a gas-liquid separator 106.

[0029] The pipe switching valve 101 includes ports 101A to 101D. The pipe switching valve 101 switches to a first state or a second state. In the first state, the first port 101A is in communication with the second port 101B, and the third port 101C is in communication with the fourth port 101D. In the second state, the first port 101A is in communication with the third port 101C, and the second port 101B is in communication with the fourth port 101D.

[0030] The vehicle air conditioner 100 includes a first pipe 111 connecting the first port 101A and the outlet 11b of the motor-driven compressor 10, a second pipe 112 connecting the second port 101B and the first heat exchanger 102, and a third pipe 113 connecting the first heat exchanger 102 and the first expansion valve 104. The vehicle air conditioner 100 also includes a fourth pipe connecting the first expansion valve 104 and the gas-liquid separator 106, a fifth pipe 115 connecting the gas-liquid separator 106 and the second expansion valve 105, a sixth pipe 116 connecting the second expansion valve 105 and the second heat exchanger 103, and a seventh pipe 117 connecting the second heat exchanger 103 and the third port 101C. In addition, the vehicle air conditioner 100 includes an eighth pipe 118 connecting the fourth port 101D and the suction port 11a of the motor-driven compressor 10.

[0031] In this structure, the injection pipe 119, which is connected to the injection connectors 43, is connected to the gas-liquid separation element 106. In addition, a shut-off valve 120 is arranged in the injection pipe 119.

[0032] The vehicle air conditioner 100 of the present embodiment is capable of performing a cooling operation and a heating operation. Specifically, the vehicle air conditioner 100 includes an air conditioning ECU 121 that controls the entire vehicle air conditioner 100, including the pipe switching valve 101. The air conditioning ECU 121 switches the pipe switching valve 101 to the first state, for example, during the cooling operation. In this case, the refrigerant is discharged from the outlet 11b and sent to the first heat exchanger 102. The refrigerant condenses upon exchanging heat with outside air in the first heat exchanger 102. The condensed refrigerant is depressurized by the first expansion valve 104 and then sent to the gas-liquid separator 106. The refrigerant is separated into liquid and gas by the gas-liquid separator 106.The liquid refrigerant is depressurized by the second expansion valve 105 and then sent to the second heat exchanger 103. The liquid refrigerant evaporates upon exchanging heat with the passenger compartment air at the second heat exchanger 103. This cools the air in the passenger compartment. The refrigerant evaporated in the second heat exchanger 103 flows toward the suction port 11a of the motor-driven compressor 10. During cooling operation, the shutoff valve 120 is closed.

[0033] The air conditioning ECU 121 switches the pipe switching valve 101 to the second state, for example, during heating operation. In this case, the refrigerant is discharged from the outlet 11b and sent to the second heat exchanger 103. The refrigerant condenses by exchanging heat with the air in the passenger compartment at the second heat exchanger 103. This heats the air in the passenger compartment. The refrigerant condensed in the second heat exchanger 103 is depressurized by the second expansion valve 105 and then sent to the gas-liquid separator 106. The refrigerant is separated into liquid and gas in the gas-liquid separator 106. The separated liquid refrigerant is depressurized in the first expansion valve 104 and then sent to the first heat exchanger 102. The refrigerant evaporates upon exchanging heat with the outside air at the first heat exchanger 102. The evaporated refrigerant flows to the suction port 11a.

[0034] The shut-off valve 120 is open during the heating operation. Therefore, the gaseous coolant, which is separated by means of the gas-liquid separator element 106, flows to the compression chamber 33 through the injection pipe 119 and the injection connections 43. This increases the flow rate of the coolant flowing into the compression chamber 33.

[0035] The gaseous fluid separated in the gas-liquid separator 106, which is the refrigerant drawn into the compression chamber 33 through the injection ports 43, has a pressure greater than that of the refrigerant drawn from the suction port 11a and lower than that of the refrigerant discharged from the outlet 11b. For the sake of brevity, in the following description, the refrigerant drawn from the suction port 11a is referred to as the inlet refrigerant. The refrigerant discharged from the outlet 11b is referred to as the compressed refrigerant. The refrigerant drawn into the compression chamber 33 through the injection ports 43 is referred to as the intermediate-pressure refrigerant. The inlet refrigerant corresponds to an "inlet fluid." The compressed refrigerant corresponds to a "compressed fluid."

[0036] In the vehicle air conditioner 100 having the above structure, after the motor-driven compressor 10 is deactivated, the intermediate pressure fluid remains in the injection pipe 119. The motor-driven compressor 10 of the present embodiment is configured to appropriately discharge the intermediate pressure fluid. This configuration will now be described along with the electrical configuration of the coil 54 of the electric motor 16 and the inverter 55.

[0037] The electrical configuration between the coil 54 and the inverter 55 will now be described. As in Fig. As shown in Figure 4, the coil 54 has a three-phase structure including, for example, a u-phase coil 54U, a v-phase coil 54V, and a w-phase coil 54W. Therefore, the electric motor 16 is a three-phase motor. The phase coils 54U, 54V, and 54W are, for example, Y-connected.

[0038] The inverter 55 includes a switching element of an upper u-phase arm Qu1 and a switching element of a lower u-phase arm Qu2, which correspond to the u-phase coil 54U. Similarly, the inverter 55 includes an upper v-phase arm switching element Qv1 and a switching element of a lower v-phase arm Qv2, which correspond to the v-phase coil 54V, and an upper w-phase arm switching element Qw1 and a switching element of a lower w-phase arm Qw2, which correspond to the w-phase coil 54W. Therefore, the inverter 55 is a so-called three-phase inverter.

[0039] The switching elements Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 are each formed, for example, using an IGBT. A power MOSFET or the like can also be used instead.

[0040] The inverter 55 includes two power lines EL1, EL2, which are connected to a DC power supply E installed in the vehicle. The inverter 55 further includes a u-phase line ELu connected to the power lines EL1, EL2. The u-phase switching elements Qu1, Qu2 are arranged on the u-phase line ELu and connected in series with each other by means of the u-phase line ELu. The section of the u-phase line ELu that connects the u-phase switching elements Qu1, Qu2 is connected to the u-phase coil 54U. The DC power supply E is an energy storage device such as a battery or an electric double-layer capacitor.

[0041] In the same way, the inverter 55 includes a v-phase conductor ELv connected to the power lines EL1, EL2. The v-phase switching elements Qv1, Qv2 are arranged at the v-phase conductor ELv. The portion of the v-phase conductor ELv connecting the v-phase switching elements Qv1, Qv2 is connected to the v-phase coil 54V. The inverter 55 includes a w-phase conductor ELw connected to the power lines EL1, EL2. The w-phase switching elements Qw1, Qw2 are arranged at the w-phase conductor ELw. The portion of the w-phase conductor ELw connecting the w-phase switching elements Qw1, Qw2 is connected to the w-phase coil 54W.

[0042] The converter 55 includes a smoothing capacitor C1 connected in parallel with the DC power supply E. The converter 55 also includes freewheeling diodes Du1 to Dw2 connected in parallel with the switching elements Qu1 to Qw2, respectively. The freewheeling diodes Du1 to Dw2 may be parasitic diodes of the switching elements Qu1 to Qw2. Alternatively, the freewheeling diodes Du1 to Dw2 may be separate from the switching elements Qu1 to Qw2.

[0043] The motor-driven compressor 10 includes a controller 60 that acts as a control device that controls the inverter 55 (specifically, switching operations of the switching elements Qu1 to Qw2) to control the rotation of the rotor 51. The controller 60 is connected to the gates of the switching elements Qu1 to Qw2. The controller 60 may be implemented by one or more dedicated hardware circuits and / or one or more processors (control circuit) operating according to a computer program (software). A processor includes a CPU and a memory such as a RAM or a ROM. The memory stores program code or instructions implemented such that the processor, for example, executes the Fig. 8. The memory, ie, a computer-readable medium, includes any usable medium accessible using a general-purpose computer or a dedicated computer.

[0044] The controller 60 performs PWM control on the inverter 55. Specifically, the controller 60 uses a carrier signal (carrier wave signal) and a command voltage signal (comparison signal) to generate a control signal. The controller 60 uses the generated control signal to cyclically apply a voltage with a predetermined pulse width δT to each of the switching elements Qu1 to Qw2. This cyclically activates and deactivates each of the switching elements Qu1 to Qw2. Consequently, DC power of the DC power supply E is converted into AC power. The AC power is supplied to the electric motor 16 to drive or generate rotation by the electric motor 16. The controller 60 is configured to be capable of changing the pulse width δT, that is, the activation / deactivation duty cycle (duty ratio), for each of the switching elements Qu1 to Qw2.

[0045] Upon activation of the motor-driven compressor 10, the control unit 60 detects the rotational position (rotation angle) at which the stationary rotor 51 is located and controls the switching elements Qu1 to Qw2 to rotate the rotor 51 based on the detection result. Specifically, the rotor 51 must be stationary upon activation of the motor-driven compressor 10. Any specific structure can be used to detect the rotational position of the rotor 51. The control unit 60 is configured to be able to detect phase currents Iu, Iv, Iw flowing to the phase coils 54U, 54V, 54W as the current flowing to the electric motor 16. Specifically, the inverter 55 includes, as shown in Fig. 4, current sensors 61-63 act as current detectors that respectively detect the current flowing through the phase wires ELu to ELw. The current sensors 61-63 are arranged, for example, between the second power line EL2 and the switching elements Qu2 to Qw2 of lower branches of the respective phase wires ELu to ELw. The current sensors 61-63 transmit the detection results to the control unit 60. The control unit 60 is capable of detecting a u-phase current Iu, which is the current flowing to the u-phase coil 54U, a v-phase current Iv, which is the current flowing to the v-phase coil 54V, and a w-phase current Iw, which is the current flowing to the w-phase coil 54W, based on the detection results of the current sensors 61-63.

[0046] Current sensors 61-63 can have any specific configuration. For example, if the configuration includes a shunt resistor, the phase currents Iu to Iw can be estimated from the voltage applied to the shunt resistor.

[0047] The control unit 60 and the air conditioning ECU 121 are electrically connected to each other and capable of exchanging information with each other. The control unit 60 activates or deactivates the motor-driven compressor 10 in response to a request, an abnormality determination result, or the like received from the air conditioning ECU 121. Deactivation of the motor-driven compressor 10 refers to a condition where the supply of AC power to the electric motor 16 is stopped, specifically, when all of the switching elements Qu1 to Qw2 are deactivated.

[0048] After a predetermined waiting period elapses from the deactivation of the motor-driven compressor 10, the controller 60 of the present embodiment executes a detection process that detects the rotation direction of the rotor 51 and the rotation frequency R, or the rotation speed, of the rotor 51 based on the detection results of the current sensors 61-63. The controller 60 that performs the detection process corresponds to a "detection unit."

[0049] Specifically, the controller 60 maintains the upper-arm switching elements Qu1, Qv1, Qw1 located on a side other than the current sensors 61-63 in the deactivation state, while the controller 60 cyclically activates and deactivates the lower-arm switching elements Qu2, Qv2, Qw2 located on a side corresponding to the current sensors 61-63 using a predetermined switching pattern. In the present embodiment, the lower-arm switching elements Qu2, Qv2, Qw2 are subjected to switching (i.e., activation / deactivation) and correspond to "subjected three-phase arm switching elements."

[0050] The control device 60 controls, for example, the switching elements Qu2, Qv2, Qw2 with respect to lower arms using a switching pattern (hereinafter referred to as the single-phase pattern) in which the switching elements Qu2, Qv2, Qw2 with respect to lower arms of the three phases are sequentially activated with one phase at a time in a predetermined order, and which includes an operation mode in which the switching element with respect to lower arms of one phase is activated while the switching elements with respect to lower arms of the remaining two phases are deactivated. In the present embodiment, as shown in (a) to (c), the Fig. 5, the single-phase pattern shows the switching element with respect to lower arms being activated in an order from the switching element Qu2 of the lower u-phase arm to the switching element Qv2 of the lower v-phase arm and then to the switching element Qw2 of the lower w-phase arm.

[0051] An operation mode with the combination that Qu2 is activated while Qu1, Qv1, Qw1, Qv2, Qw2 are deactivated is referred to as the first operation mode. An operation mode with the combination that Qv2 is activated while Qu1, Qv1, Qw1, Qu2, Qw2 are deactivated is referred to as the second operation mode. In this case, the controller 60 switches from the first operation mode to the second operation mode by cyclically activating and deactivating the switching elements Qu2, Qv2, Qw2 with respect to lower arms. In other words, the switching mode used in the deceleration control (single-phase pattern) includes the first operation mode and the second operation mode having different combinations of the activated and deactivated switching elements Qu1 to Qw2.

[0052] The single-phase pattern is a switching pattern set such that among the switching elements Qu2, Qv2, Qw2 with respect to lower arms of the three phases, the switching elements with respect to lower arms of multiple phases (two phases or three phases) are not activated at the same time.

[0053] The single-phase pattern is not limited to the switching pattern in which the switching element is constantly activated with respect to lower arms of any of the three phases as shown in (a) to (c) of the Fig. 5, and may include an interval time period during which the switching elements Qu2, Qv2, Qw2 relating to lower arms are all deactivated. The single-phase pattern may be a switching pattern in which, for example, the switching elements relating to lower arms are sequentially activated with one phase at a time in a predetermined order between the aforementioned interval time periods, and the switching element relating to lower arms of one phase is activated while the switching elements relating to lower arms of the remaining two phases are deactivated.

[0054] In the present embodiment, the lower-arm switching elements Qu2, Qv2, Qw2 rise to the activation state at different timings separated from each other by a predetermined time period δa. Specifically, the time period from a time point when the lower-arm switching element Qu2 rises to a time point when the lower-arm switching element Qv2 rises, the time period from a time point when the lower-arm switching element Qv2 rises to a time point when the lower-arm switching element Qw2 rises, and the time period from a time point when the lower-arm switching element Qw2 rises to a time point when the lower-arm switching element Qu2 rises are the same predetermined time period δa.In this configuration, the single-phase pattern is a switching pattern in which the pulse width δT is set to be less than or equal to the predetermined period δa. When the pulse width δT is less than the predetermined period δa, the phase pattern is a switching pattern in which the switching elements related to lower arms are sequentially activated with one phase at a time in the predetermined order between the interval periods (three-phase deactivation periods). When the pulse width δT is equal to the predetermined period δa, the single-phase pattern is a switching pattern in which the switching elements related to lower arms are sequentially activated with one phase at a time in the predetermined order without the interval period.

[0055] The relationship between the rotation direction and the rotation frequency R of the rotor 51 and the phase currents Iu, Iv, Iw will be explained below with reference to Fig. 6 and Fig. 7 described.

[0056] Fig. 6 is a schematic graph showing the phase currents Iu, Iv, Iw detected when the rotor 51 rotates in the forward direction. Fig. Figure 7 is a schematic graph showing the phase currents Iu, Iv, Iw detected when the rotor rotates in the reverse direction. For ease of illustration, one cycle of a minimum unit wave (single triangular wave) of each of the phase currents Iu, Iv, Iw is extended from the current cycle.

[0057] Fig. 6 and Fig. Figure 7 shows the current waveforms of the phase currents Iu, Iv, Iw when the switching elements Qu2, Qv2, Qw2 are constantly activated and deactivated with respect to the lower arms. Therefore, the actual switching of the switching elements Qu2, Qv2, Qw2 with respect to the lower arms in the single-phase pattern achieves one-third of the number of triangular waves formed by the phase currents Iu, Iv, Iw, as shown in Fig. 6 and Fig. 7 are shown.

[0058] As in Fig. 6 and Fig. As shown in Figure 7, the phase currents Iu, Iv, and Iw (specifically, the envelopes of phase currents Iu, Iv, and Iw) have different phases. Therefore, a phase current with a positive value shifts sequentially with the passage of time. A phase current has a positive value when the phase coil corresponding to the phase current with the positive value generates a smaller counter electromotive force than the other phase coils.

[0059] The shift order of the phase current with a positive value differs between the situation when the rotor 51 rotates in the forward direction and the situation when the rotor 51 rotates in the reverse direction. In particular, as shown in Fig. 6, when the rotor 51 rotates in the forward direction, the phase current with a positive value shifts in order from the u-phase current Iu to the v-phase current Iv and then the w-phase current Iw. However, as shown in Fig. 6, when the rotor 51 rotates in the reverse direction, the phase current having a positive value changes in order from the w-phase current Iw to the v-phase current Iv and then the u-phase current Iu.

[0060] A positive current period Ta, during which the phase current has a positive value, corresponds to one third of a cycle of the electrical angle of the rotor 51.

[0061] The control device 60 detects the rotation direction and the rotation frequency R of the rotor 51 based on the above characteristics and the current waveforms obtained from the detection results of the current sensors 61-63 when the switching elements Qu2, Qv2, Qw2 are switched with respect to lower arms in the single-phase pattern.

[0062] Specifically, when the switching elements Qu2, Qv2, Qw2 are connected with respect to lower arms in the single-phase pattern, current waveforms of the phase currents Iu, Iv, Iw are obtained in accordance with the current rotation direction and the current rotation frequency R. The controller 60 detects the shift order of the phase current with a positive value from the current waveforms. The controller 60 determines whether the rotation direction of the rotor 51 is forward or reverse based on the detection result.

[0063] The control device 60 detects the positive current period Ta from the current waveforms obtained by switching in the single-phase pattern. The control device 60 derives the rotation frequency R of the rotor 51 based on the detected positive current period Ta.

[0064] The above characteristics do not change even if the switching pattern of the lower-arm switching elements Qu2, Qv2, Qw2 changes. Specifically, the characteristics include an aspect such that the shift order of the positive-value phase current differs in accordance with the rotation direction, and an aspect such that the positive-current period Ta corresponds to one-third of a cycle of the rotor 51. Therefore, even if the lower-arm switching elements Qu2, Qv2, Qw2 are switched in a two-phase pattern, the control device 60 detects the rotation direction and the rotation frequency R of the rotor 51 based on the above characteristics and the current waveforms acquired by the current sensors 61-63. Details of the two-phase pattern will be described below.

[0065] In response to detecting that the rotor 51 is rotating in the reverse direction through the detection process, the controller 60 executes a reverse rotation control process that controls the rotation frequency of the rotor 51 rotating in the reverse direction. The reverse rotation control process will now be described.

[0066] As in Fig. 8, in step S101, the control device 60 executes deceleration control that reduces the rotation frequency R to a target rotation frequency Rt. The control device 60 that executes the process of step S101 corresponds to a "deceleration control element."

[0067] The target rotation frequency Rt is set to be less than or equal to a predetermined rotation frequency tolerance Ra. Specifically, when the rotor 51 rotates reversely, the motor-driven compressor 10 generates noise, vibration, or the like. The noise and vibration tend to increase with increasing rotation frequency R. In this aspect, the rotation frequency tolerance Ra is the maximum value at which the noise and vibration are allowable.

[0068] The deceleration control of the present embodiment will now be described in detail. In the deceleration control, the control device 60 decelerates the rotor 51 by activating at least one of the switching elements Qu1 to Qw2. In the present embodiment, in the deceleration control, the control device 60 activates and deactivates the lower-arm switching elements Qu2, Qv2, Qw2 with a predetermined switching pattern to sequentially switch the lower-arm switching element that is activated. Specifically, in the deceleration control, the control device 60 uses a switching control mode that switches (activates / deactivates) the lower-arm switching elements Qu2, Qv2, Qw2 to sequentially switch the lower-arm switching element that is activated. The sequential switching of the lower-arm switching element that is activated indicates that the lower-arm switching element is activated.indicates that the combination of the activated and deactivated switching elements Qu1 to Qw2 (especially the switching elements Qu2, Qv2, Qw2 with respect to lower branches) is changed sequentially.

[0069] In this case, the switching elements Qu2, Qv2, Qw2 are adjusted with respect to lower branches to have the same switching frequency.

[0070] In this configuration, when the positive-phase current corresponding to the lower-arm switching element being activated is applied, heat is generated in the phase coil corresponding to the lower-arm switching element being activated. This converts the kinetic energy of the rotor 51 into thermal energy and decelerates the rotor 51. In the following description, the effect of decelerating the rotor 51 by converting the kinetic energy of the rotor 51 into thermal energy is referred to as the braking effect.

[0071] The phase current and phase coil corresponding to the switching element related to the lower branches being activated refer to the u-phase current Iu and the u-phase coil 54U when the switching element Qu2 of the lower u-phase branch is activated. Similarly, the v-phase current Iv and the v-phase coil 54V refer to the switching element Qv2 of the lower v-phase branch being activated. The w-phase current Iw and the w-phase coil 54W refer to the switching element Qw2 of the lower w-phase branch being activated.

[0072] In this configuration, heat tends to be generated as the phase currents Iu, Iv, Iw increase. This increases the braking effect. In particular, as the phase currents Iu, Iv, Iw increase, a greater deceleration force tends to be applied to the rotor 51.

[0073] The counter electromotive force generated in the phase coils 54U, 54V, and 54W increases as the rotation frequency R increases. Furthermore, the phase currents Iu, Iv, and Iw increase more easily as the counter electromotive force increases. Therefore, the phase currents Iu, Iv, and Iw depend on the rotation frequency R.

[0074] In this regard, the control device 60 starts the deceleration control by cyclically activating and deactivating the switching elements Qu2, Qv2, Qw2 with respect to lower arms using a predetermined initial deceleration duty ratio and a predetermined initial deceleration switching pattern. In the present embodiment, the initial switching pattern is the single-phase pattern. The initial deceleration duty ratio is set according to a predetermined tolerance value and the counter electromotive force generated when the rotation frequency R is the expected maximum value, so that the phase currents Iu, Iv, Iw flowing due to switching in the single-phase pattern do not exceed the tolerance value when the rotation frequency R is the maximum value expected in a situation where the intermediate-pressure coolant causes reverse rotation.Specifically, the initial delay duty cycle and the initial switching pattern are set so that the phase currents Iu, Iv, Iw do not exceed the tolerance value regardless of the rotation frequency R of the rotor 51. The tolerance value is, for example, the rated current value of the switching elements Qu1 to Qw2 or a value less than the rated current value by a predetermined margin.

[0075] Then, the control device 60 variably controls at least one of the switching pattern and the activation / deactivation duty ratio of the switching elements Qu2, Qv2, Qw2 with respect to the lower branches such that the phase currents Iu, Iv, Iw increase within a range that does not exceed the tolerance value, based on the detection results of the phase currents Iu, Iv, Iw. For example, the control device 60 gradually increases the duty ratio (relative on-time) from the initial delay duty ratio such that the phase currents Iu, Iv, Iw do not exceed the tolerance value.

[0076] As described above, in the switching pattern of the present embodiment, the lower-arm switching elements Qu2, Qv2, Qw2 ascend to the activation state at different timings separated from each other by a predetermined time period δa. Specifically, the time period from a time point when the lower-arm switching element Qu2 ascends to a time point when the lower-arm switching element Qv2 ascends, the time period from a time point when the lower-arm switching element Qv2 ascends to a time point when the lower-arm switching element Qw2 ascends, and the time period from a time point when the lower-arm switching element Qw2 ascends to a time point when the lower-arm switching element Qu2 ascends are the same predetermined time period δa.When the duty ratio increases and the pulse width δT of each of the switching elements Qu2, Qv2, Qw2 with respect to lower arms becomes larger than the predetermined period δa, the switching pattern is switched from the single-phase pattern to the two-phase pattern.

[0077] As in (a) to (c) of the Fig. 9, the two-phase pattern is a switching pattern in which the switching elements Qu2, Qv2, Qw2 with respect to lower arms of the three phases are sequentially activated with two phases simultaneously in a predetermined order, and which includes an operation mode in which the switching elements with respect to lower arms of two phases are activated while the switching element with respect to lower arms of the remaining phase is deactivated. In the two-phase pattern, the switching elements with respect to lower arms that are activated are switched, for example, in the order of the switching element Qu2 of the lower u-phase arm and the switching element Qv2 of the lower v-phase arm, the switching element Qv2 of the lower v-phase arm and the switching element Qw2 of the lower w-phase arm, the switching element Qw2 of the lower w-phase arm and the switching element Qu2 of the lower u-phase arm, and so on.In the two-phase pattern of the present embodiment, the switching elements Qu1, Qv1, Qw1 all remain in the deactivation state.

[0078] For example, an operation mode with the combination of Qu2, Qv2 activated while Qu1, Qv1, Qw1, Qw2 are deactivated is referred to as the first operation mode. An operation mode with the combination of Qv2, Qw2 activated while Qu1, Qv1, Qw1, Qu2 are deactivated is referred to as the second operation mode. In this case, the control device 60 switches from the first operation mode to the second operation mode by cyclically activating and deactivating the switching elements Qu2, Qv2, Qw2 with respect to lower arms. In other words, the switching mode used in the deceleration control (two-phase pattern) includes the first operation mode and the second operation mode having different combinations of the activated and deactivated switching elements Qu1 to Qw2.

[0079] The two-phase pattern is not limited to the switching pattern in which the switching elements are constantly activated with respect to lower branches of any two of the three phases, as shown in (a) to (c) of the Fig. 9, and may include a single-phase activation period in which the switching element related to lower arms of one phase is activated while the switching elements related to lower arms of the two phases are deactivated. The two-phase pattern may be a switching pattern in which switching occurs in the order of, for example, Qu2 is activated while Qv2, Qw2 are deactivated; Qu2, Qv2 are activated while Qw2 is deactivated; Qv2 is activated while Qu2, Qw2 are deactivated; Qv2, Qw2 are activated while Qu2 is deactivated; Qw2 is activated while Qu2, Qv2 are deactivated; Qu2, Qw2 are activated while Qv2 is deactivated; etc. Therefore, the two-phase pattern may be a switching pattern in which the switching elements related to lower arms are sequentially activated with two phases simultaneously in a predetermined order between single-phase activation periods (two-phase deactivation periods).

[0080] The two-phase pattern may include a three-phase activation period during which the switching elements Qu2, Qv2, Qw2 with respect to lower arms are all activated. The two-phase pattern may be a switching pattern in which switching occurs, for example, in the order of Qu2, Qv2 are activated while Qw2 is deactivated; Qu2, Qv2, Qw2 are activated; Qv2, Qw2 are activated while Qu2 is deactivated; Qu2, Qv2, Qw2 are activated; Qu2, Qw2 are activated while Qv2 is deactivated; Qu2, Qv2, Qw2 are activated; Qu2, Qv2 are activated while Qw2 is deactivated; etc. Therefore, the two-phase pattern may be a switching pattern in which the switching elements with respect to lower arms are sequentially activated with two phases simultaneously in a predetermined order between the three-phase activation periods.

[0081] When the pulse width δT of each of the switching elements Qu2, Qv2, Qw2 with respect to lower arms is less than twice the predetermined period δa, the two-phase pattern is a switching pattern in which the switching elements with respect to lower arms are sequentially activated with two phases simultaneously in the predetermined order between the single-phase activation periods. When the pulse width δT of each of the switching elements Qu2, Qv2, Qw2 with respect to lower arms is greater than twice the predetermined period δa, the two-phase pattern is a switching pattern in which the switching elements with respect to lower arms are sequentially activated with two phases simultaneously in the predetermined order between the three-phase activation periods.When the pulse width δT of each of the lower-arm switching elements Qu2, Qv2, Qw2 is equal to or less than twice the predetermined period δa, the two-phase pattern is a switching pattern in which the lower-arm switching elements are sequentially activated in two phases simultaneously in the predetermined order, excluding the single-phase activation period and the three-phase activation period. The braking effect tends to increase as the duty cycle (duty factor) increases.

[0082] When the lower-arm switching elements Qu2, Qv2, Qw2 are configured to be switched in a two-phase pattern, a mode of operation is used in which the lower-arm switching elements of two phases are activated simultaneously. Therefore, the lower-arm switching element is activated according to the positive-value phase current at a switching frequency of two out of three times in the mode of operation. Therefore, the two-phase pattern increases the phase currents Iu, Iv, Iw more easily than the single-phase pattern.

[0083] After the switching pattern is switched from the single-phase pattern to the two-phase pattern, the control device 60 further gradually increases the duty cycle in a range such that the phase currents Iu, Iv, Iw do not exceed the tolerance value.

[0084] The phase currents Iu, Iv, and Iw depend on the rotation frequency R. Therefore, during deceleration, where the rotation frequency R is gradually reduced, the actual phase currents Iu, Iv, and Iw do not always increase even if the switching pattern and duty cycle are variably controlled to slightly increase the phase currents in a gradual manner. In particular, the variable control of the switching pattern and duty cycle, which act to gradually increase the phase currents Iu, Iv, and Iw, does not necessarily increase the actual phase currents Iu, Iv, and Iw, and only needs to limit a decrease in the phase currents Iu, Iv, and Iw according to the deceleration.

[0085] The control device 60 detects the current rotation frequency R of the rotor 51 from waveforms of the phase currents Iu, Iv, Iw obtained by the deceleration control. The control device 60 continues the deceleration control until the rotation frequency R becomes the target rotation frequency Rt, and ends the deceleration control when the rotation frequency R becomes the target rotation frequency Rt. The time when execution of the process of step S101 is started corresponds to the time when the deceleration control is started. The time when the rotation frequency R becomes the target rotation frequency Rt corresponds to the time when the deceleration control is ended. The control device 60 stores a first time period T1, which is the execution time period of the deceleration control. The first time period T1 varies according to the state during deactivation.

[0086] As in Fig. As shown in Fig. 8, when the rotation frequency R decreases to the target rotation frequency Rt, the controller 60 proceeds to step S102 and executes continuation control, which continues the reverse rotation of the rotor 51. The controller 60 that executes the process of step S102 corresponds to a "continuation control element."

[0087] During the continuation control, the control device 60 controls the inverter 55 so that the rotation frequency R is maintained at the target rotation frequency Rt. Specifically, the control device 60 starts the continuation control by cyclically enabling and disabling the switching elements Qu2, Qv2, Qw2 with respect to lower arms using a predetermined initial continuation switching pattern and a predetermined initial continuation duty ratio. In the present embodiment, the initial continuation switching pattern and the initial continuation duty ratio are a switching pattern and a duty ratio that are set when the deceleration control is terminated.

[0088] The intermediate-pressure coolant is discharged during the reverse rotation of the rotor 51. The discharge of the intermediate-pressure coolant reduces the pressure of the intermediate-pressure coolant in the injection pipe 119. This reduces the kinetic energy that rotates the rotor 51 backward. Therefore, when the shift control continues in the same mode, the rotation frequency R gradually decreases due to the reduction of the kinetic energy corresponding to the reverse rotation of the rotor 51.

[0089] In this regard, in the present embodiment, the control device 60 variably controls at least one (in the present embodiment, both) of the switching pattern and the duty ratio such that the phase currents Iu, Iv, Iw gradually decrease. Specifically, the control device 60 gradually decreases the duty ratio such that the rotation frequency R is maintained at the target rotation frequency Rt. Moreover, when the switching pattern is the two-phase pattern and the duty ratio becomes a lower limit value corresponding to the two-phase pattern, the control device 60 switches the switching pattern to the single-phase pattern and gradually further decreases the duty ratio.

[0090] In this configuration, the thermal energy absorbed by the electric motor 16 decreases in accordance with the reduction in kinetic energy resulting from the discharge of the intermediate-pressure coolant. This tends to maintain the rotation frequency R at the target rotation frequency Rt.

[0091] The control device 60 detects the present rotation frequency R from waveforms of the phase currents Iu, Iv, Iw obtained by the continuation control, and performs feedback control on the switching pattern and the duty ratio such that the obtained rotation frequency R becomes close to the target rotation frequency Rt. Specifically, during the continuation control, the control device 60 controls the phase currents Iu, Iv, Iw according to changes in the pressure of the intermediate-pressure coolant in the injection pipe 119 such that the rotation frequency R becomes close to the target rotation frequency Rt.

[0092] The control device 60 performs the continuation control during a second time period T2 that is longer than the first time period T1 which is the execution time period of the delay control. In particular, during the continuation control, the control device 60 regularly determines whether a predetermined continuation control termination condition is satisfied or not. The continuation control termination condition includes, for example, both a condition (A) where the execution time period of the continuation control (i.e., the second time period T2) is longer than the first time period T1, and a condition (B) where the phase currents Iu, Iv, Iw are less than or equal to a predetermined termination trigger current value.

[0093] The termination trigger current value is set according to a state in which the intermediate-pressure coolant is properly discharged from the injection pipe 119, in other words, a state in which, after stopping, the rotor 51 is not moved by the intermediate-pressure coolant. Specifically, the control device 60 includes mapping data in which the shift control modes (specifically, shift pattern and duty ratio) are mapped to the termination trigger current values. Each termination trigger current value corresponds to the phase currents Iu, Iv, Iw obtained when the pressure of the remaining intermediate-pressure coolant in the injection pipe 119 is a predetermined tolerance pressure value during execution of the shift control associated with the termination trigger current value.

[0094] The control device 60 detects the termination trigger current value corresponding to the current switching control mode by referring to the map data and determines whether the phase currents Iu, Iv, Iw flowing due to the switching control are less than or equal to the termination trigger current value. If the phase currents Iu, Iv, Iw are less than or equal to the termination trigger current value, the control device 60 determines that condition (B) is satisfied.

[0095] The control device 60 continues the execution of the continuation control until the continuation control termination condition is satisfied.

[0096] When the continuation control termination condition is satisfied, the controller 60 proceeds to step S103 and executes deactivation control that stops the rotor 51. Specifically, the controller 60 maintains all of the lower-arm switching elements Qu2, Qv2, Qw2 in the deactivation state. That is, the controller 60 short-circuits all of the phase coils 54U, 54V, 54W. The deactivation control may be referred to as the deceleration control in which the lower-arm switching elements Qu2, Qv2, Qw2 of the three phases are all set to the activation state and the duty ratio is set to 100%.

[0097] The operation of the present embodiment will now be described with reference to Fig. 10 described. Fig. Figure 10 is a schematic graph showing changes in the rotation frequency R following deactivation. In Fig. 10 “+” indicates the forward direction, and “-” indicates the reverse direction.

[0098] As in Fig. As shown in Figure 10, at time t1, when the motor-driven compressor 10 is deactivated, the rotation frequency R of the rotor 51 gradually decreases. At time t2, the rotation direction of the rotor 51 is switched from the forward direction to the reverse direction. Subsequently, the rotation frequency R becomes greater than the target rotation frequency Rt and the rotation frequency tolerance Ra.

[0099] At time t3, the detection process is executed. When the reverse rotation of the rotor 51 is detected, deceleration control is started. Consequently, the kinetic energy is converted into thermal energy, and the rotor 51 begins to decelerate. In this case, as described above, the braking effect gradually increases. Therefore, the deceleration rate of the rotation frequency R gradually increases.

[0100] At time t4, when the rotation frequency R becomes equal to the target rotation frequency Rt, the deceleration control is switched to the continuation control. In this case, the first period T1 goes from time t3 to time t4. The difference in the rotation frequency R between time T3, which is the start time of the deceleration control, and time t4, which is the end time of the deceleration control, is referred to as a deceleration rotation frequency difference δR1 (deceleration rotation speed difference).

[0101] During continuation control, the rotation frequency R is maintained at the target rotation frequency Rt. In this case, the actual rotation frequency R does not fully correspond to the target rotation frequency Rt and fluctuates slightly. However, a continuation rotation frequency difference δR2 (continuation rotation speed difference), which is the difference between the minimum value and the maximum value of the rotation frequency R during continuation control, is sufficiently smaller than the deceleration rotation frequency difference δR1. The continuation rotation frequency difference δR2 corresponds to the fluctuation difference of the rotation frequency R of the rotor 51 during continuation control.

[0102] At time t5, when the continuation control termination condition is met, the switching control is switched from continuation control to termination control. At time t6, the reverse rotation of the rotor 51 stops. In this case, the second period T2 goes from time t4 to time t5.

[0103] The present embodiment has the advantages described below.

[0104] (1) The motor-driven compressor 10 includes the electric motor 16 including the rotor 51, the housing 11 provided with the suction port 11a that sucks in the refrigerant acting as a fluid, and the compression unit 15 that compresses the inlet refrigerant sucked in from the suction port 11a and discharges the compressed refrigerant. The compression unit 15 includes the fixed roller 31 fixed to the housing 11, the movable roller 32 engaged with the fixed roller 31 and capable of orbiting the fixed roller 31, and the compression chamber 33 defined by the fixed roller 31 and the movable roller 32.The compression unit 15 is configured to compress the inlet refrigerant sucked into the compression chamber 33 when the movable roller 32 orbits in the forward direction when the rotor 51 rotates in the forward direction.

[0105] In this configuration, the motor-driven compressor 10 includes the injection ports 43 that draw the intermediate-pressure refrigerant into the compression chamber 33 at a pressure higher than that of the inlet refrigerant and lower than that of the compressed refrigerant, the inverter 55 that drives the electric motor 16, and the controller 60 that controls the inverter 55. The controller 60 executes deceleration control that decelerates the rotor during the first period T1 in response to rotation of the rotor 51 in a direction opposite to the forward direction. After completion of the deceleration control, the controller 60 executes continuation control that continues the reverse rotation of the rotor 51 during the second period T2, which is longer than the first period T1.The continuation rotation frequency difference δR2 (continuation rotation speed difference), which is the difference between the maximum value and the minimum value of the rotation frequency R (rotation speed) of the rotor 51 obtained during the continuation control, is smaller than the deceleration rotation frequency difference δR1 (deceleration rotation speed difference), which is the difference in the rotation frequency R between the start time of the deceleration control and the end time of the deceleration control.

[0106] In this configuration, when the rotor 51 rotates reversely, the rotor is decelerated during the first time period T1. Then, the reverse rotation of the rotor 51 continues at a relatively low rotation frequency R during the second time period T2, which is longer than the first time period T1. Therefore, the intermediate pressure coolant is discharged while noise and vibration are limited.

[0107] In particular, noise and vibration tend to increase as the rotation frequency R increases. Therefore, if the high rotation frequency R continues for a long time, noise and vibration may be annoying. However, if the rotor 51 is forcibly and quickly stopped, the intermediate pressure refrigerant continues to remain in the injection pipe 119. This may cause the reverse rotation recurrence activity in which, after the rotation of the rotor 51 is stopped, the rotor 51 rotates backward again. The reverse rotation recurrence activity offsets the rotation position of the rotor 51 and may interfere with the activation of the motor-driven compressor 10, in which the switching elements Qu1 to Qw2 are controlled based on the rotation position of the rotor 51.

[0108] In this regard, in the present embodiment, deceleration control is performed first. Then, when the rotation frequency R is reduced, continuation control is performed. In continuation control, the fluctuation of the rotation frequency R is small compared to the deceleration control. This allows continuation control to easily maintain the reverse rotation of the rotor 51 at a relatively low rotation frequency R. Therefore, noise and vibration are limited during continuation control. In addition, continuation control is performed during the second period T2, which is longer than the first period T1. This sufficiently discharges the intermediate pressure coolant. In addition, the first period T1, which is the execution period of deceleration control corresponding to a relatively high rotation frequency R, is shorter than the second period T2. Therefore, noise and vibration cannot be disturbing.Therefore, the occurrence of reverse rotation recurrence activity is limited, while noise and vibration are limited. This limits the interference with the activation of the motor-driven compressor 10 caused by the intermediate pressure refrigerant.

[0109] (2) In the deceleration control, the control device 60 decelerates the rotor until the rotation frequency R of the rotor 51 becomes the target rotation frequency Rt, which is set to be less than or equal to the predetermined rotation frequency tolerance Ra. In the continuation control, the control device 60 continues the rotation of the rotor 51 during the second period T2 while maintaining the rotation frequency R at the rotation frequency tolerance Ra or less. With this configuration, during the continuation control, the rotation frequency R is less than or equal to the rotation frequency tolerance Ra. This limits noise and vibration in a further preferable manner.

[0110] (3) In the continuation control, the controller 60 controls the inverter 55 such that the rotation frequency R is maintained at the target rotation frequency Rt. With this configuration, the rotation frequency R is maintained at a high level compared to a configuration that gradually decreases the rotation frequency R from the target rotation frequency Rt. This facilitates the discharge of the intermediate-pressure coolant and discharges the intermediate-pressure coolant promptly. Consequently, the second time period T2 can be shortened. This shortens the time period until the rotor 51 is stopped.

[0111] (4) The inverter 55 includes the upper-arm switching elements Qu1, Qv1, Qw1 and the lower-arm switching elements Qu2, Qv2, Qw2, in which those of the same phase are connected to each other. The control device 60 controls the switching elements Qu1 to Qw2. In the deceleration control, the control device 60 sequentially switches the lower-arm switching element that is activated by cyclically activating and deactivating the lower-arm switching elements Qu2, Qv2, Qw2 while maintaining the upper-arm switching elements Qu1, Qv1, Qw1 in the deactivation state.

[0112] In this configuration, when the phase current flows according to the activated switching element with respect to the lower arms, the kinetic energy of the rotor 51 is converted into thermal energy. This decelerates the rotor 51.

[0113] The switching elements Qu2, Qv2, Qw2 related to the lower arms can be maintained in the deactivation state without being cyclically activated and deactivated. However, if the switching elements Qu2, Qv2, Qw2 related to the lower arms are maintained in the deactivation state, the phase currents Iu, Iv, Iw would increase excessively and exceed the tolerance value. In this regard, in the present embodiment, the switching elements Qu2, Qv2, Qw2 related to the lower arms are configured to be cyclically activated and deactivated. This limits excessive increases in the phase currents Iu, Iv, Iw.

[0114] Furthermore, in the present embodiment, the activated switching element is switched sequentially with respect to lower arms. Therefore, the phase currents Iu, Iv, Iw have the same level. This reduces the phase current of each phase to achieve the desired braking effect. Therefore, excessive increases in the phase currents Iu, Iv, Iw upon deceleration of the rotor 51 are limited. Accordingly, the rotation frequency of the rotor 51 is immediately reduced, while interference with the operation of the inverter 55, which would be caused by excessive increases in the current flowing to the electric motor 16, is limited. This limits noise and vibration.

[0115] Furthermore, since the activated lower-arm switching elements are switched sequentially, differences in heat generation amount among the three lower-arm switching elements Qu2, Qv2, Qw2 are reduced. This limits situations where only a specific lower-arm switching element generates excessive heat among the three lower-arm switching elements Qu2, Qv2, Qw2. Consequently, the rotor 51 is decelerated while limiting the local heat generation of the specific lower-arm switching element.

[0116] (5) Specifically, the braking effect is achieved when the lower-arm switching element corresponding to the phase current having a positive value is activated. The lower-arm switching element, to which the phase current having a positive value can flow, is switched sequentially in a predetermined order. Therefore, when the lower-arm switching element of only one designated phase is configured to be cyclically activated and deactivated, deceleration is performed only during a period in which the phase current corresponding to the designated phase has a positive value. In this case, the rotor 51 is intermittently decelerated. This may result, for example, in a failure to achieve the appropriate braking effect or in unstable reverse rotation of the rotor 51.

[0117] In this regard, in the present embodiment, the lower-arm switching element that is activated is switched sequentially. Therefore, the lower-arm switching element is activated according to the phase current having a positive value at a predetermined frequency (at least once out of three times in the present embodiment). This enables continuous deceleration and limits the above-mentioned undesirable situations.

[0118] Further, for example, the positive current period Ta of each of the phase currents Iu, Iv, Iw can be detected in advance to control cyclic activation and deactivation of only the lower-arm switching element corresponding to the positive current period Ta. However, to perform this control, the rotational position of the rotor 51 must be detected. Furthermore, the rotational position must be synchronized with the switching of the lower-arm switching elements Qu2, Qv2, Qw2. This may result in the need for a separate rotation angle sensor such as a resolver or the need to perform complicated control, and therefore cause a complicated configuration.

[0119] In this regard, in the present embodiment, the lower-arm switching element that is activated is switched sequentially as described above. Therefore, the rotor 51 decelerates without the need to detect the rotational position of the rotor 51 or synchronize the rotational position with the switching of the lower-arm switching elements Qu2, Qv2, Qw2. This simplifies the configuration.

[0120] (6) The control device 60 starts the deceleration control by cyclically activating and deactivating the switching elements Qu2, Qv2, Qw2 with respect to the lower arms using the predetermined initial deceleration switching pattern and the predetermined initial deceleration duty ratio. Then, the control device 60 variably controls at least one of the switching pattern and the duty ratio of the switching elements Qu2, Qv2, Qw2 with respect to the lower arms such that the phase currents Iu, Iv, Iw increase within a range not exceeding the tolerance value. With this configuration, the rotation frequency R of the rotor 51 is reduced in a relatively smooth manner while limiting an excessive increase in the phase currents Iu, Iv, Iw upon starting the deceleration control.

[0121] Specifically, the phase currents Iu, Iv, Iw increase more easily as the rotation frequency R of the rotor 51 increases. Therefore, if the switching pattern and duty ratio that slightly increase the phase currents Iu, Iv, Iw are set from the beginning of the acceleration control, which is when the rotation frequency R is high, the phase currents Iu, Iv, Iw would tend to increase excessively. However, if the deceleration control is continued using the switching pattern and duty ratio that slightly decrease the phase currents Iu, Iv, Iw, a decrease in the rotation frequency R of the rotor 41 would be hindered.

[0122] In this regard, in the present embodiment, the deceleration control starts using the initial deceleration switching pattern and the initial deceleration duty cycle, and then the switching elements Qu2, Qv2, Qw2 with respect to lower arms are controlled to increase within a range such that the phase currents Iu, Iv, Iw do not exceed the tolerance value. This increases the braking effect while limiting a situation where the phase currents Iu, Iv, Iw increase excessively when the deceleration control is started. This makes it possible to shorten the first time period T1.

[0123] (7) The control device 60 starts the continuation control by cyclically activating and deactivating the switching elements Qu2, Qv2, Qw2 with respect to lower arms using the initial continuation switching pattern and the initial continuation duty ratio. Then, the control device 60 variably controls at least one of the switching pattern and the duty ratio of the switching elements Qu2, Qv2, Qw2 with respect to lower arms such that the phase currents Iu, Iv, Iw gradually decrease. With this configuration, after the continuation control is started, the thermal energy consumed by the electric motor 16 gradually decreases. Therefore, during the continuation control, the rotation frequency R is maintained at a certain level even if the kinetic energy gradually decreases due to decreases in pressure when the intermediate-pressure coolant is discharged from the injection ports 43.This avoids a situation where the continuation rotation frequency difference δR2 exceeds the deceleration rotation frequency difference δR1.

[0124] (8) After the continuation control is completed, the control device 60 executes the deactivation control, which stops the rotation of the rotor 51. With this configuration, the rotation of the rotor 51 is stopped promptly compared to a configuration in which the rotor 51 spontaneously decelerates after the continuation control is completed. This shortens the time period from when the deceleration control is started to when the reverse rotation of the rotor is stopped.

[0125] (9) The control device 60 detects the rotation direction and the rotation frequency R of the rotor 51 based on the phase currents Iu, Iv, Iw flowing under the deceleration control and the continuation control. With this configuration, the rotation direction and the rotation frequency R of the rotor 51 are detected without using a dedicated sensor or the like. This can achieve a sensorless configuration. Furthermore, the deceleration control and the continuation control can be effectively used by detecting the rotation direction and the rotation frequency R of the rotor 51 based on the phase currents Iu, Iv, Iw flowing as a result of the deceleration control and the continuation control. In other words, energy control related to the detection of the rotation direction and the rotation frequency R of the rotor 51 does not need to be performed. This can simplify the control.

[0126] The above embodiment can be modified as follows.

[0127] Continuation control is not limited to control that maintains the rotation frequency R at the target rotation frequency Rt. Continuation control may, for example, be control that gradually decreases the rotation frequency R in a range such that the continuation rotation frequency difference δR2 is smaller than the continuation rotation frequency difference δR1.

[0128] In the continuation control, the control device 60 may control the switching elements Qu2, Qv2, Qw2 with respect to lower arms such that the rotation frequency R increases within a range less than or equal to the rotation frequency tolerance Ra. Alternatively, the control device 60 may alternately repeat acceleration and deceleration. The continuation control only needs to be executed for a time longer than the first period T1 when the continuation rotation frequency difference δR2 is smaller than the deceleration rotation frequency difference δR1. The rotation frequency R can be changed in each specific operation mode during the continuation control. The difference in the rotation frequency R between a time when the deceleration control is started and a time when the deceleration control is terminated can be used as the continuation rotation frequency difference δR2.

[0129] The deceleration control and the continuation control are not limited to those of the embodiment and may include any specific switching control mode. For example, the control device 60 may be configured to cyclically activate and deactivate the switching element related to lower arms of only one predetermined fixed phase and maintain the switching element related to lower arms of the remaining phase in the deactivation state. Alternatively, the control device 60 may be configured to cyclically activate and deactivate the switching elements Qu2, Qv2, Qw2 related to lower arms of the three phases by synchronizing the rising timing and the falling timing.

[0130] In the deceleration control, the control device 60 only needs to use the switching pattern and duty ratio that make it easier to increase the phase currents Iu, Iv, Iw as the rotation frequency R decreases. The switching pattern and duty ratio can be changed in each specific operation mode.

[0131] In the deceleration control, the control device 60 may be configured not to change the switching pattern and the duty ratio from the initial deceleration switching pattern and the initial deceleration duty ratio. Similarly, in the continuation control, the control device 60 may be configured not to change the switching pattern and the duty ratio from the initial continuation switching pattern and the initial continuation duty ratio.

[0132] The initial continuation switching pattern and the initial continuation duty ratio are not limited to the switching pattern and the duty ratio obtained when the deceleration control is finished, and may be any switching pattern and any duty ratio as long as the rotation frequency R does not fluctuate excessively.

[0133] The target rotation frequency Rt that triggers the termination of the deceleration control may be different from the target rotation frequency Rt maintained in the continuation control. For example, the controller 60 may execute the deceleration control until the rotation frequency R becomes a first target rotation frequency, and then continue the reverse rotation of the rotor such that the rotation frequency R becomes close to a second target rotation frequency instead of the first target rotation frequency. In this case, the second target rotation frequency is preferably less than or equal to the rotation frequency tolerance Ra. The first target rotation frequency may be less than or equal to the rotation frequency tolerance Ra, or slightly greater than the rotation frequency tolerance Ra.

[0134] The deactivation control can be omitted. In this case, the rotor 51 decelerates spontaneously and stops.

[0135] The termination trigger condition for the deceleration control is not limited to a state where the rotation frequency R becomes the target rotation frequency Rt. The termination trigger condition for the deceleration control may be, for example, a state where a predetermined first time period T1 ends from the start time point of the deceleration control.

[0136] Condition (B) may be omitted from the continuation control termination condition. In this case, the second time period T2 is preferably set so that the intermediate pressure refrigerant is sufficiently discharged regardless of the state during deactivation.

[0137] If condition (B) is omitted, the second time period T2 can be set to correspond to the first time period T1. For example, the second time period T2 can be set to be longer as the first time period T1 shortens. Therefore, if the discharge amount of the intermediate-pressure refrigerant is small during the deceleration control due to the first time period T1, the discharge amount of the intermediate-pressure refrigerant can be increased during the continuation control. This discharges the intermediate-pressure refrigerant sufficiently.

[0138] In the exemplary embodiment, the respective branch switching elements of the three phases subjected to switching are the lower-branch switching elements Qu2, Qv2, Qw2. Instead, for example, the upper-branch switching elements Qu1, Qv1, Qw1 may be used. In particular, the control device 60 may cyclically activate and deactivate the upper-branch switching elements Qu1, Qv1, Qw1 such that the upper-branch switching element that is activated is switched sequentially. In this case, the lower-branch switching elements Qu2, Qv2, Qw2 preferably retain the deactivation state, for example. The current sensors 61-63 are preferably arranged at the phase conductors ELu to ELw between the upper-branch switching elements Qu1, Qv1, Qw1 and the first power line EL1.

[0139] Therefore, in the deceleration control, the control device 60 may use a switching control mode that switches the upper-arm switching elements Qu1, Qv1, Qw1 to sequentially switch the upper-arm switching element that is activated.

[0140] The control device 60 can switch (i.e., cyclically activate and deactivate) both the switching elements Qu1, Qv1, Qw1 relating to upper branches and the switching elements Qu2, Qv2, Qw2 relating to lower branches. In particular, the respective branch switching elements of the three phases subjected to switching can be both the switching elements Qu1, Qv1, Qw1 relating to upper branches of the three phases and the switching elements Qu2, Qv2, Qw2 relating to lower branches of the three phases. In this case, the control device 60 preferably controls the switching elements such that the switching element relating to upper branches and the switching element relating to lower branches of the same phase are not activated simultaneously.Specifically, the control device 60 may employ a switching control mode that sequentially switches the upper-arm switching element that is activated and also sequentially switches the lower-arm switching element that is activated, such that the upper-arm switching element and the lower-arm switching element of the same phase are not simultaneously activated.

[0141] Specifically, in the deceleration control, the control device 60 only needs to decelerate the rotor 51 by activating at least one of the switching elements Qu1, Qv1, Qw1 related to upper arms of the three phases and the switching elements Qu2, Qv2, Qw2 related to lower arms of the three phases. In this case, the switching control mode used by the control device 60 in the deceleration control only needs to include the first mode in which one or more of the switching elements Qu1 to Qw2 is activated while the remaining switching elements are deactivated, and the second mode that differs from the first mode in the combination of the switching element that is activated and the switching element that is deactivated. This limits situations in which only a certain switching element generates heat locally. Therefore, the rotor 51 is sufficiently decelerated.

[0142] The second operating mode only needs to differ from the first operating mode in the combination of the activation and deactivation states of the switching elements Qu1 to Qw2. Therefore, in the second operating mode, some of the switching elements of the phases that are activated may be the same as in the first operating mode. For example, in the two-phase pattern, an operating mode in which Qu2, Qv2 are activated while Qu1, Qv1, Qw1, Qw2 are deactivated is called the first operating mode. An operating mode in which Qv2, Qw2 are activated while Qu1, Qv1, Qw1, Qu2 are deactivated is called the second operating mode. In this case, the switching element Qv2 of the lower v-phase arm is activated in both the first operating mode and the second operating mode. However, the switching element Qu2 of the lower u-phase arm is activated in the first operating mode, and the switching element Qw2 of the lower w-phase arm is activated in the second operating mode.Therefore, the first operating mode and the second operating mode have different switching elements of the phases that are activated.

[0143] The control device 60 may be configured to variably control one of the switching pattern and the duty ratio. For example, the control device 60 may set the switching pattern to one of the single-phase pattern and the two-phase pattern and variably control only the duty ratio. Alternatively, the control device 60 may set the duty ratio and switch the switching pattern to the single-phase pattern or the two-phase pattern. The control device 60 only needs to variably control at least one of the switching pattern and the duty ratio according to the rotation frequency R.

[0144] The single-phase pattern may include any order of the lower-arm switching element being activated. For example, the single-phase pattern may be configured to switch the lower-arm switching element being activated in a sequence from the switching element Qw2 of the lower w-phase arm to the switching element Qv2 of the lower v-phase arm, and then to the switching element Qu2 of the lower u-phase arm. The two-phase pattern may be configured in the same way.

[0145] The two-phase pattern can have any combination of phases activated simultaneously.

[0146] The switching pattern may have any specific operating mode as long as the respective branch switching element being activated is switched sequentially. The switching pattern may have an operating mode in which, for example, the respective branch switching elements of one phase are simultaneously activated sequentially in a predetermined order between the three-phase activation periods during which the respective branch switching elements of the three phases are all activated.

[0147] In the two-phase pattern of the embodiment, the switching elements Qu2, Qv2, Qw2 with respect to lower arms ascend to the activation state at different timings. Instead, the two-phase pattern may, for example, be a switching pattern in which the switching elements with respect to lower arms ascend from two phases to the activation state at the same timing. For example, the two-phase pattern may be a pattern in which switching occurs in the order of Qu2, Qv2 are activated while Qw2 is deactivated; Qu2, Qv2, Qw2 are deactivated; Qv2, Qw2 are activated while Qu2 is deactivated; Qu2, Qv2, Qw2 are deactivated; Qu2, Qw2 are activated while Qv2 is deactivated; Qu2, Qv2, Qw2 are deactivated; Qu2, Qv2 are activated while Qw2 is deactivated; etc.Therefore, the two-phase pattern may be a switching pattern in which the respective branch switching elements are sequentially activated with two phases simultaneously in a predetermined order between interval periods during which the respective branch switching elements of the three phases are all deactivated. In other words, the two-phase pattern only needs to include at least one of a switching pattern including the interval period, a switching pattern including the single-phase activation period, a switching pattern including the three-phase activation period, and a switching pattern that does not include any of the interval period, the single-phase activation period, and the three-phase activation period.

[0148] In the embodiment, the switching elements Qu2, Qv2, Qw2 with respect to lower arms ascend to the activation state at different timings. Therefore, the switching pattern is switched to the single-phase pattern or the two-phase pattern by adjusting the duty ratio. However, as described above, when the switching elements Qu2, Qv2, Qw2 with respect to lower arms ascend to the activation state at the same timing (i.e., there is no phase difference), adjusting the duty ratio does not switch the switching pattern. Therefore, the duty ratio and the switching pattern may or may not be linked.

[0149] The control device 60 may have any specific structure for detecting the rotation direction and rotation frequency R of the rotor 51. For example, the structure may include a rotation angle sensor such as a resolver, and perform the detection based on the detection result of the rotation angle sensor.

[0150] When a predetermined condition is met, for example, when the rotation direction of the rotor 51 obtained by the detection control is the reverse direction, and the rotation frequency R obtained by the detection process is less than or equal to a predetermined threshold, the control device 60 does not need to execute at least one of the deceleration control and the continuation control. In particular, the control device 60 is not limited to the configuration that always executes the deceleration control and the continuation control after the motor-driven compressor 10 is deactivated (ie, when the rotor 51 rotates reversely). The control device 60 may be configured to execute the deceleration control and the continuation control when a specified condition is met (ie,when the reverse rotation frequency R is greater than the above threshold) after the motor-driven compressor 10 is deactivated. The control device 60 only needs to act to perform the deceleration control and the continuation control.

[0151] The threshold can be any value, as long as the value is relatively small. For example, the threshold can be the target rotation frequency Rt or less. Alternatively, the threshold can be greater than the target rotation frequency Rt and less than the rotation frequency tolerance Ra. Alternatively, the threshold can be, for example, the rotation frequency tolerance Ra.

[0152] The injection ports 43 can be arranged in any position. Any number of injection ports 43 can be used.

[0153] The object on which the motor-driven compressor 10 is installed is not limited to a vehicle and may be any object.

[0154] The motor-driven compressor 10 is used with the air conditioning system 100, but can be used with another device. For example, if the vehicle is a fuel cell vehicle (FCV) that includes a fuel cell, the motor-driven compressor 100 can be used with a supply device that supplies air to the fuel cell. Therefore, the object of compression can be any fluid. The fluid can be a coolant or air.

[0155] The embodiment and modified examples can be combined. For example, the control device 60 may be configured to switch the switching elements Qu1, Qv1, Qw1 related to upper arms of the three phases to sequentially switch the switching element related to upper arms that is activated, and then switch the switching elements Qu2, Qv2, Qw2 related to lower arms of the three phases to sequentially switch the switching element related to lower arms that is activated. Alternatively, the control device 60 is configured to switch the switching elements Qu1, Qv1, Qw1 related to upper arms of the three phases or the switching elements Qu2, Qv2, Qw2 related to lower arms of the three phases and then switch all of the switching elements Qu1 to Qw2.

[0156] Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

[0157] A motor-driven compressor includes an electric motor including a rotor, a housing, a compression unit, a drive circuit, and a controller. The controller includes deceleration control means that performs deceleration control that decelerates the rotor during a first period in response to the rotor rotating in a direction opposite to the forward direction, and continuation control means that performs continuation control that continues the rotation of the rotor during a second period longer than the first period after the deceleration control is performed. A fluctuation difference of a rotation frequency of the rotor during the continuation control is smaller than a deceleration rotation frequency difference.

Claims

[1] Motor-driven compressor (10), with an electric motor (16) including a rotor (51), a housing (11) including a suction port (11a) which sucks in a fluid, a compression unit (15) driven by the electric motor (16), the compression unit (15) compressing an inlet fluid, which is the fluid sucked in through the suction port (11a), and discharging a compressed fluid, which is the compressed inlet fluid, a drive circuit (55) which drives the electric motor (16), and a control device (60) which controls the drive circuit (55) to control rotation of the rotor (51), wherein the compression unit (15) has a fixed roller (31) attached to the housing (11), a movable roller (32) engaged with the fixed roller (31) and adapted to orbit the fixed roller (31), and a compression chamber (33) defined by the fixed roller (31) and the movable roller (32), wherein, when the rotor (51) rotates in a predetermined forward direction, the movable roller (32) orbits in the forward direction, and the compression unit (15) thereby compresses the inlet fluid sucked into the compression chamber (33), wherein the motor-driven compressor (10) further comprises an injection port (43) which sucks an intermediate pressure fluid into the compression chamber (33), the intermediate pressure fluid having a pressure higher than that of the inlet fluid and lower than that of the compressed fluid, wherein the control device (60) comprises a deceleration control device that performs a deceleration control that decelerates the rotor (51) during a first period in response to rotating the rotor (51) in a direction opposite to the forward direction, and a continuation control means which performs a continuation control which continues the rotation of the rotor (51) during a second period of time which is longer than the first period of time after the deceleration control is performed, and wherein a fluctuation difference of a rotation frequency of the rotor (51) during the continuation control is less than a deceleration rotation frequency difference, which is a difference between a rotation frequency of the rotor (51) when the deceleration control is started and a rotation frequency of the rotor (51) when the deceleration control is ended. [2] Motor-driven compressor (10) according to claim 1, wherein the deceleration control means is arranged to decelerate the rotor (51) until the rotation frequency of the rotor (51) becomes a target rotation frequency, the target rotation frequency being set to be less than or equal to a predetermined rotation frequency tolerance, and the continuation control device is configured to continue the rotation of the rotor (51) while maintaining the rotation frequency of the rotor (51) such that the rotation frequency of the rotor (51) is less than or equal to the rotation frequency tolerance during the second time period. [3] A motor-driven compressor (10) according to claim 2, wherein the continuation control means is arranged to control the drive circuit (55) such that the rotation frequency of the rotor (51) is maintained at the target rotation frequency. [4] Motor-driven compressor (10) according to one of claims 1 to 3, wherein the electric motor (16) is a three-phase motor, the drive circuit (55) has a switching element of an upper u-phase branch (Qu1) and a switching element of a lower u-phase branch (Qu2) which are connected to each other, a switching element of an upper v-phase branch (Qv1) and a switching element of a lower v-phase branch (Qv2) which are connected to each other, and a switching element of an upper w-phase branch (Qw1) and a switching element of a lower w-phase branch (Qw2) which are connected to each other, the control device (60) is configured to control switching of the switching elements relating to upper branches of the three phases (Qu1, Qv1, Qw1) and of the switching elements relating to lower branches of the three phases (Qu2, Qv2, Qw2), and wherein in the deceleration control, the deceleration control means controls the drive circuit (55) in a switching control mode including a first mode in which one or more switching elements among the switching elements relating to upper arms of the three phases (Qu1, Qv1, Qw1) and the switching elements relating to lower arms of the three phases (Qu2, Qv2, Qw2) are activated while the remaining switching elements are deactivated, and a second mode different from the first mode with respect to a combination of the activated and deactivated switching elements. [5] A motor-driven compressor (10) according to claim 4, wherein the switching control mode in the deceleration control comprises one of the following: an operation mode that switches the switching elements with respect to upper arms of the three phases (Qu1, Qv1, Qw1) to sequentially switch the switching element with respect to upper arms that is activated, an operation mode that switches the switching elements related to lower arms of the three phases (Qu2, Qv2, Qw2) to sequentially switch the switching element related to lower arms that is activated, and an operation mode that switches the switching elements related to upper arms of the three phases (Qu1, Qv1, Qw1) and switches the switching elements related to lower arms of the three phases (Qu2, Qv2, Qw2) to switch the switching element that is activated sequentially without simultaneously activating the switching element related to upper arms and the switching element related to lower arms of the same phase. [6] The motor-driven compressor (10) according to claim 5, wherein the deceleration control means is configured to start the deceleration control by cyclically activating and deactivating respective branch switching elements of the three phases (Qu1, Qv1, Qw1, Qu2, Qv2, Qw2) subjected to switching using a predetermined initial deceleration switching pattern and a predetermined initial deceleration duty ratio, and then variably control at least one of a switching pattern and a duty ratio of the respective branch switching elements of the three phases (Qu1, Qv1, Qw1, Qu2, Qv2, Qw2) such that a current flowing to the three-phase motor (16) increases within a range not exceeding a predetermined tolerance value. [7] The motor-driven compressor (10) according to claim 6, wherein the initial deceleration switching pattern and the initial deceleration duty cycle are set such that the current flowing to the three-phase motor (16) does not exceed the tolerance value regardless of the rotation frequency of the rotor (51). [8] The motor-driven compressor (10) according to any one of claims 4 to 7, wherein the continuation control means is configured to start the continuation control by cyclically activating and deactivating the respective branch switching elements of the three phases (Qu1, Qv1, Qw1, Qu2, Qv2, Qw2), which are one or both of the switching elements related to upper arms of the three phases (Qu1, Qv1, Qw1) and the switching elements related to lower arms of the three phases (Qu2, Qv2, Qw2), using a predetermined initial continuation switching pattern and a predetermined initial continuation duty ratio, and then variably controlling at least one of a switching pattern and a duty ratio of the respective branch switching elements of the three phases (Qu1, Qv1, Qw1, Qu2, Qv2, Qw2) to gradually decrease a current flowing to the three-phase motor (16). [9] The motor-driven compressor (10) according to any one of claims 1 to 8, wherein the control means (60) is adapted to perform a deactivation control that stops the rotation of the rotor (51) after completion of the continuation control.

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