Electric compressor control device

Abstract

To suppress reduction in product life and failure while considering startability during initial running-in of an electric compressor.SOLUTION: A control device for an electric compressor detects a rotor position of an electric motor provided as a power source in the electric compressor in a sensor-less manner to execute a sensor-less mode for controlling energization to a stator coil. When the sensor-less mode is executed, whether or not running-in operation of the electric compressor is completed is monitored based on a time when the drive of the electric motor becomes effective for initial running-in of the electric compressor. When a start-up mode is executed as a pre-stage of the sensor-less mode, a start-up current ISTART is set to a high current value IH before it is determined that the running-in operation is completed, and set to a low current value IL after it is determined that the running-in operation is completed.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a control device for an electric compressor. [Background technology]

[0002] A sensorless mode is known in which an electric motor, during normal operation, controls current flow to the stator coil by detecting the rotor position using an induced voltage generated in the stator coil without using a sensor. When an electric motor driven in this sensorless mode is started, no induced voltage is generated in the stator coil, so it is usually difficult to immediately detect the rotor position using a sensorless mode. For this reason, when the electric motor is started, a start-up mode is executed as a step before switching to the sensorless mode, in which the rotor is forcibly rotated using forced commutation without taking the rotor position into consideration, thereby generating an induced voltage (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-110177 Summary of the Invention [Problem to be solved by the invention]

[0004] In an electric compressor having the electric motor as its power source, a startup mode may be executed by setting a relatively high startup current in advance, taking into consideration the start-up performance during the initial break-in period at the beginning of use. However, if the startup mode with such a relatively high startup current is executed every time the compressor is started, it may unnecessarily accelerate the deterioration of semiconductor switching elements in the motor drive circuit and mechanical sliding parts of the electric compressor, resulting in a shortened product life or failure.

[0005] In view of the above-mentioned problems of the related art, an object of the present invention is to provide a control device for an electric compressor that suppresses shortening of product life and failures while taking into consideration the start-up performance during the initial running-in of the electric compressor. [Means for solving the problem]

[0006] In order to achieve the above object, the control device for an electric compressor of the present invention executes a sensorless mode in which the rotor position of an electric motor provided as a power source of the electric compressor is detected without a sensor and the current supply to a stator coil is controlled, and during execution of the sensorless mode, it is determined whether or not the break-in operation of the electric compressor is completed based on the time during which the drive of the electric motor becomes effective for the initial break-in of the electric compressor. judgement death, When it is determined that the break-in operation has not been completed, information indicating that the break-in operation has not been completed is stored, and when it is determined that the break-in operation has been completed, the information indicating that the break-in operation has not been completed is rewritten to information indicating that the break-in operation has been completed. When executing startup mode as a preliminary step to sensorless mode, the startup current is set as follows: If information indicating that the break-in period is not complete is stored is set to a first current value, If information indicating the completion of break-in is stored is set to a second current value lower than the first current value. [Effects of the Invention]

[0007] According to the control device for an electric compressor of the present invention, it is possible to suppress a decrease in product life and failures while taking into consideration the start-up performance during the initial running-in of the electric compressor. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of a refrigeration cycle to which an electric compressor is applied. [Figure 2] FIG. 2 is a circuit block diagram showing an example of a drive control system for an electric compressor. [Figure 3] 4 is a flowchart showing an example of electric motor control processing of the first example motor control device. [Figure 4] FIG. 2 is a block diagram showing an example of a sensorless mode functional configuration of the motor control device. [Figure 5] 4 is a flowchart showing an example of a sensorless mode process of the motor control device. [Figure 6] FIG. 2 is a block diagram showing an example of a startup mode functional configuration of the motor control device. [Figure 7] 4 is a flowchart showing an example of a start-up mode process of the motor control device. [Figure 8] FIG. 10 is a block diagram showing an example of the start-up mode functional configuration of a second example motor control device. [Figure 9] 4 is a flowchart showing an example of a start-up mode process of the motor control device. [Figure 10] FIG. 10 is a block diagram showing an example of the start-up mode functional configuration of a third example motor control device. [Figure 11] 4 is a flowchart showing an example of a start-up mode process of the motor control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of a refrigeration cycle to which a compressor is applied.

[0010] Refrigeration cycle 1 is a vapor pressure refrigeration cycle configured with a compressor 3, a condenser 4, an expansion valve 5, and an evaporator 6 arranged in this order around refrigerant piping 2 through which refrigerant circulates. Compressor 3 compresses low-temperature, low-pressure gaseous refrigerant to produce high-temperature, high-pressure gaseous refrigerant. Condenser 4 cools the high-temperature, high-pressure gaseous refrigerant that has passed through compressor 3 to produce low-temperature, high-pressure liquid refrigerant. Expansion valve 5 decompresses the low-temperature, high-pressure liquid refrigerant to produce low-temperature, low-pressure liquid refrigerant. Evaporator 6 vaporizes the low-temperature, low-pressure liquid refrigerant to produce low-temperature, low-pressure gaseous refrigerant. This type of refrigeration cycle 1 can be applied to a variety of devices, whether on-board or stationary, such as air conditioners and heat pumps.

[0011] 2 shows a schematic configuration example of a drive control system for compressor 3. Compressor 3 and electric motor 7, which serves as its power source, constitute electric compressor 8, and motor drive circuit 9, which drives electric motor 7, is controlled by motor control device 10, which has a built-in computer. In this way, motor control device 10 functions as a controller for electric compressor 8. Electric compressor 8, motor drive circuit 9, and motor control device 10 are housed in an integrally formed housing, but this does not exclude the possibility of at least motor control device 10 being housed in an independent housing separate from electric compressor 8.

[0012] The electric motor 7 is a permanent magnet synchronous motor having a stator including a stator coil in which one end of each of a U-phase coil 71, a V-phase coil 72, and a W-phase coil 73 is connected in a star connection, and a rotor including a permanent magnet. In the drawing, only the stator coil consisting of the three-phase coils 71, 72, and 73 is shown, and the other coils are not shown. Furthermore, although a star connection is used as an example of the connection type of the three-phase coils 71, 72, and 73, a delta connection may be used instead.

[0013] The motor drive circuit 9 is a three-phase bridge circuit including six switching elements 91 to 96 that converts DC power supplied from a DC power supply 11 into three-phase AC power. Specifically, a U-phase arm, a V-phase arm, and a W-phase arm are connected in parallel between a positive power line 11a extending from the high potential side of the DC power supply 11 and a negative power line 11b extending from the low potential side of the DC power supply 11. The U-phase arm is formed by connecting two switching elements 91 and 92 in series, and a connection line between the switching elements 91 and 92 is connected to the other end of the U-phase coil 71. The V-phase arm is formed by connecting two switching elements 93 and 94 in series, and a connection line between the switching elements 93 and 94 is connected to the other end of the V-phase coil 72. The W-phase arm is formed by connecting two switching elements 95 and 96 in series, and a connection line between the switching elements 95 and 96 is connected to the other end of the W-phase coil 73. In the figure, the switching elements 91 to 96 are IGBTs (Insulated Gate Bipolar Transistors) that perform switching operations in response to a gate signal Sg, but other semiconductor switching elements that perform switching operations in response to an external control signal may be used. For example, MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors) may be used instead of IGBTs.

[0014] The motor drive circuit 9 also has current sensors 97-99. The current sensor 97 measures the U-phase current Iu and outputs a current measurement signal Siu reflecting the measurement value. The current sensor 98 measures the V-phase current Iv and outputs a current measurement signal Siv reflecting the measurement value. The current sensor 99 measures the W-phase current Iw and outputs a current measurement signal Siw reflecting the measurement value. In the figure, the current sensors 97-99 are each shown as a shunt-type current sensor that amplifies and outputs the potential difference across a shunt resistor, and this shunt resistor is interposed between the lower arm switching elements 92, 94, 96 and the negative side power line 11b. Note that instead of using shunt resistors, Hall ICs may be used as the current sensors 97-99.

[0015] Motor control device 10 receives current measurement signals Siu, Siv, and Siw and applied voltage signals Svu, Svv, and Svw, and outputs gate signals Sg to each of switching elements 91-96 of motor drive circuit 9 based on these signals. Applied voltage signal Svu reflects the value of U-phase applied voltage Vu applied to the other end of U-phase coil 7u, applied voltage signal Svv reflects the value of V-phase applied voltage Vv applied to the other end of V-phase coil 7v, and induced voltage signal Svw reflects the value of W-phase applied voltage Vw applied to the other end of W-phase coil 7w. A pre-driver that adjusts the signal level of gate signal Sg may be interposed between motor control device 10 and motor drive circuit 9 so that switching elements 91-96 can be switched.

[0016] Specifically, during normal operation of the electric compressor 8, the motor control device 10 executes a sensorless mode in which the rotor position (rotation angle of the rotor) is estimated from the induced voltage and interlinkage magnetic flux generated in the three-phase coils 71, 72, 73, thereby controlling the energization of the three-phase coils 71, 72, 73. On the other hand, when starting the electric compressor 8, the motor control device 10 executes a start-up mode in which the rotor is forcibly rotated by forced commutation without considering the rotor position, as a preliminary step before transitioning to the sensorless mode. This takes into account the fact that when the electric compressor 8 starts, no induced voltage is generated in the three-phase coils 71, 72, 73 because the rotor is stopped, and therefore the rotor position cannot be immediately detected in a sensorless manner.

[0017] FIG. 3 shows an outline of the control process for driving the electric motor 7 in the motor control device 10. The motor control device 10 performs control processes for driving the electric motor 7 by having a processor in an internal computer read out control programs, constants, etc., that are pre-stored in non-volatile memory into volatile memory and execute them. Specifically, in response to an external input of an operation command, the motor control device 10 executes a startup mode in step S1 (abbreviated as "S1" in the figure, and the same applies below), and executes a sensorless mode in step S2. Note that the motor control device 10 may embody some or all of the control processes for driving the electric motor 7 in hardware rather than via software.

[0018] [Motor control device of the first example] Next, a motor control device 10A, which is a first example of the motor control device 10 configured as described above, will be described with reference to FIGS.

[0019] 4 shows an example of the functional configuration of motor control device 10A when executing sensorless mode. As functions when executing sensorless mode, motor control device 10A has phase current acquisition unit 101, applied voltage acquisition unit 102, rotor position estimator 103, rotational speed calculation unit 104, three-phase to two-axis conversion unit 105, and target rotational speed holding unit 106. Furthermore, as functions when executing sensorless mode, motor control device 10A has current command value calculation unit 107, voltage command value calculation unit 108, two-axis to three-phase conversion unit 109, and gate signal generation unit 110.

[0020] The phase current acquisition unit 101 acquires the values ​​of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw based on the input current measurement signals Siu, Siv, and Siw (for example, by performing A / D conversion on the current measurement signals Siu, Siv, and Siw).

[0021] The applied voltage acquisition unit 102 acquires the values ​​of the three-phase applied voltages Vu, Vv, and Vw based on the input applied voltage signals Svu, Svv, and Svw (for example, by performing A / D conversion on the applied voltage signals Svu, Svv, and Svw).

[0022] As a preparation for estimating the rotor position θm, the rotor position estimator 103 first calculates a U-phase induced voltage Eu, a V-phase induced voltage Ev, and a W-phase induced voltage Ew. The values ​​of the three-phase induced voltages Eu, Ev, and Ew are obtained by substituting the values ​​of the corresponding phases of the three-phase currents Iu, Iv, and Iw and the values ​​of the corresponding phases of the three-phase applied voltages Vu, Vv, and Vw into a relational expression between the induced voltages, phase currents, and applied voltages in the corresponding phases. The rotor position estimator 103 then estimates the rotor position θm of the electric motor 7 based on the three-phase currents Iu, Iv, and Iw and the three-phase induced voltages Eu, Ev, and Ew.

[0023] Specifically, the rotor position estimator 103 calculates the peak values ​​of the phase current waveforms (phase current peak values) and the electrical angles (phase current electrical angles) based on the acquired values ​​of the three-phase currents Iu, Iv, and Iw, assuming that the three-phase currents Iu, Iv, and Iw vary in a cosine function pattern with respect to the electrical angle with a phase difference of 120 degrees. The rotor position estimator 103 also calculates the peak values ​​of the induced voltage waveforms (induced voltage peak values) and the electrical angles (induced voltage electrical angles) based on the acquired values ​​of the three-phase induced voltages Eu, Ev, and Ew, assuming that the three-phase induced voltages Eu, Ev, and Ew vary in a cosine function pattern with respect to the electrical angle with a phase difference of 120 degrees. The rotor position estimator 103 then acquires the current phase by referring to a predetermined data table in which the phase current peak values, induced voltage electrical angles, and phase current electrical angles are previously associated with the current phase, and calculates the rotor position θm based on the phase current electrical angles and the current phase. Here, the current phase is a parameter that indicates the phase relationship between the d-axis component (d-axis current) and the q-axis component (q-axis current) of the vector of the input current to the electric motor 7 in the dq-axis rotating coordinate system of the rotor. Note that instead of estimating the rotor position θm using this method (for details, see, for example, Japanese Patent Application Laid-Open No. 2011-10438), it is also possible to estimate the rotor position θm using other methods, such as detecting the zero crossings of the three-phase induced voltages Eu, Ev, and Ew.

[0024] The rotational speed calculation unit 104 calculates the current rotational speed ω [rad / s] of the rotor using the estimated rotor position θm (for example, as the time rate of change of two consecutively acquired rotor positions θm).

[0025] Based on the estimated rotor position θm, the three-phase-two-axis conversion unit 105 converts the three-phase currents Iu, Iv, Iw in the three-phase stationary coordinate system of the stator into d-axis and q-axis currents Id, Iq in the dq-axis rotating coordinate system of the rotor.

[0026] The target rotation speed holding unit 106 temporarily holds the value of the target rotation speed ωa [rad / s] included in an external operation command in a volatile memory such as a RAM (Random Access Memory).

[0027] The current command value calculation unit 107 performs feedback control of the rotation speed using PI control or the like based on the deviation between the target rotation speed ωa and the current rotation speed ω of the rotor, and calculates command values ​​for the input current of the electric motor 7 as d-axis and q-axis current command values ​​Id*, Iq* in a dq-axis rotating coordinate system.

[0028] The voltage command value calculation unit 108 performs feedback control of the input current to the electric motor 7 by PI control or the like based on the deviation between the value of the d-axis current Id and the d-axis current command value Id*, the deviation between the value of the q-axis current Iq and the q-axis current command value Iq*, and the current rotational speed ω of the rotor. As a result, the voltage command value calculation unit 108 calculates command values ​​for the voltages applied to the electric motor 7 as d-axis and q-axis voltage command values ​​Vd*, Vq* in a dq-axis rotating coordinate system.

[0029] Based on the estimated rotor position θm, a two-axis-to-three-phase conversion unit 109 converts the d-axis and q-axis voltage command values ​​Vd*, Vq* in the dq-axis rotating coordinate system of the rotor into three-phase voltage command values ​​in the three-phase stationary coordinate system of the stator, i.e., U-phase, V-phase and W-phase voltage command values ​​Vu*, Vv*, Vw*.

[0030] The gate signal generating unit 110 generates the gate signal Sg based on the three-phase voltage command values ​​Vu*, Vv*, and Vw*. For example, the gate signal generating unit 110 can generate, as the gate signal Sg, a PWM (Pulse Width Modulation) signal obtained by comparing the three-phase voltage command values ​​Vu*, Vv*, and Vw* with a carrier such as a triangular wave.

[0031] Although not directly related to the driving of the electric motor 7, the motor control device 10A further includes a break-in time calculation unit 111, a break-in completion determination unit 112, and a break-in completion flag storage unit 113 as functional components for use in the sensorless mode.

[0032] The break-in time calculation unit 111 integrates the time during which the electric motor 7 is driven, which is effective for the initial break-in of the electric compressor 8, when the sensorless mode is being executed while the break-in operation of the electric compressor 8 is not yet completed, and calculates the integrated value as the break-in time Σt BRK The running-in time calculation unit 111 stores the running-in time in a writable nonvolatile memory such as a flash memory as the running-in time. The driving of the electric motor 7 that is effective for the initial running-in of the electric compressor 8 is the driving of the electric motor 7 that makes at least one of the magnitude of the torque generated by the electric motor 7 and the magnitude of the current flowing through the electric motor 7 equal to or greater than a threshold value that is defined for each of the generated torque and the current. For example, the running-in time calculation unit 111 can determine whether the driving of the electric motor 7 is effective for the initial running-in of the electric compressor 8, based on the three-phase currents Iu, Iv, and Iw.

[0033] Here, the initial running-in of the electric compressor 8 refers to sufficient smoothing of the friction surfaces of the mechanical sliding parts of the electric compressor 8. Furthermore, the running-in operation of the electric compressor 8 refers to driving the electric motor 7 until it is estimated that the initial running-in is complete. Therefore, the timing at which the initial running-in is complete does not necessarily coincide with the timing at which the running-in operation is complete.

[0034] The break-in completion determination unit 112 determines whether the break-in time Σt BRKBased on the result of the above, it is determined whether or not the initial running-in of the electric compressor 8 is considered to be complete. If the initial running-in is considered to be complete, the run-in completion determination unit 112 determines that the run-in of the electric compressor 8 is complete, and if the initial running-in is considered to be incomplete, it determines that the run-in of the electric compressor 8 is not complete.

[0035] The break-in completion flag storage unit 113 rewrites the value of the break-in completion flag F, which indicates whether the break-in of the electric compressor 8 has been completed, as necessary based on the determination result of the break-in completion determination unit 112, and stores the rewritten value in a writable nonvolatile memory such as a flash memory. For example, if the value of the break-in completion flag F is 0 when it is determined that the break-in is not completed, the value of the break-in completion flag F is rewritten to 1 when it is determined that the break-in is completed.

[0036] 5 shows an example of a break-in completion flag setting process, which is one of the control processes performed in the sensorless mode in the motor control device 10A, and is performed by the functions of the break-in time calculation unit 111, the break-in completion determination unit 112, and the break-in completion flag storage unit 113. The break-in completion flag setting process is repeatedly performed at a control period Δt while the sensorless mode is being executed.

[0037] In step S11, motor control device 10A uses break-in time calculation unit 111 to refer to the value of break-in completion flag F stored in break-in completion flag storage unit 113 to determine whether or not the break-in of electric compressor 8 has been completed. If motor control device 10A determines that the break-in of electric compressor 8 has been completed (YES), it temporarily terminates the break-in completion flag setting process, whereas if it determines that the break-in of electric compressor 8 has not been completed (NO), it proceeds to step S102.

[0038] In step S12, the motor control device 10A, using the break-in time calculation unit 111, determines whether or not the electric motor 7 is being driven in a manner that is effective for the initial break-in of the electric compressor 8. For example, the motor control device 10A can determine whether or not the electric motor 7 is being driven in a manner that is effective for the initial break-in of the electric compressor 8 based on whether or not the value of the square root of the sum of squares calculated from each value of the three-phase currents Iu, Iv, and Iw is equal to or greater than a threshold value. Alternatively, the motor control device 10A may determine whether or not the electric motor 7 is being driven in a manner that is effective for the initial break-in based on a comparison between the torque generated by the electric motor 7, calculated from the values ​​of the d-axis and q-axis currents Id and Iq, and a threshold value, or a comparison between the square root of the sum of squares of the d-axis and q-axis currents Id and Iq and a threshold value. Then, if the motor control device 10A determines that the electric motor 7 is being driven in a manner that is effective for the initial break-in of the electric compressor 8 (YES), the process proceeds to step S13. On the other hand, if the motor control device 10A determines that the electric motor 7 is not being driven in a manner that is effective for the initial running-in of the electric compressor 8 (NO), the motor control device 10A temporarily ends the running-in completion flag setting process.

[0039] In step S13, motor control device 10A calculates, by break-in time calculation unit 111, the control period Δt in the break-in completion flag setting process by multiplying the current break-in time Σt BRK Add to the new break-in time Σt BRK Get.

[0040] In step S14, motor control device 10A determines a new break-in time Σt BRK is equal to or greater than a predetermined value a. This predetermined value a is a value greater than 0 that is stored in advance in the nonvolatile memory as the time required for the initial running-in of the electric compressor 8. Then, the motor control device 10A determines whether the new running-in time Σt BRK If it is determined that the running-in time Σt is equal to or greater than the predetermined value a (YES), the running-in time of the electric compressor 8 is considered to be completed, and the process proceeds to step S15. BRK If it is determined that the running-in completion flag is less than the predetermined value a (NO), the running-in completion flag setting process is temporarily terminated, assuming that the running-in completion flag of the electric compressor 8 is not yet completed.

[0041] In step S15, the motor control device 10A causes the run-in completion flag storage unit 113 to rewrite the value of the run-in completion flag F from a value indicating that the run-in operation is not yet complete (for example, 0) to a value indicating that the run-in operation is complete (for example, 1). Then, in step S16, the motor control device 10A calculates the run-in time Σt BRK is reset to zero, and the break-in completion flag setting process is temporarily terminated.

[0042] 6 shows an example of the functional configuration of motor control device 10A when the startup mode is executed. Note that functions that are similar between the sensorless mode and the startup mode are given the same reference numerals, and only the differences from the sensorless mode will be described.

[0043] The startup mode is initiated when the motor control device 10A receives an external operation command. The functional configuration during startup mode execution is broadly divided into three functions: startup current selection, forced commutation, and startup determination. The startup current selection function includes a startup current selector 114 and a run-in completion flag storage unit 113. The forced commutation function includes a current command value calculator 107, a voltage command value calculator 108, a two-axis-to-three-phase converter 109, a gate signal generator 110, and a virtual rotor position calculator 115. The startup determination function includes a phase current acquirer 101, an applied voltage acquirer 102, a rotor position estimator 103, a virtual rotor position calculator 115, and a startup determination unit 116. While the target rotational speed holder 106 holds the target rotational speed ωa included in the operation command, this target rotational speed ωa is not used during startup mode execution in the first example. The same applies to the startup modes described below.

[0044] In response to an external operation command, the starting current selection unit 114 selects a starting torque T that does not affect the startability of the electric compressor 8 based on the value of the break-in completion flag F stored in the nonvolatile memory. START The starting current I START Specifically, the start-up current selection unit 114 selects the high current value I H or low current value I LSelect either the high current value I H is the starting torque T that does not affect the starting performance of the electric compressor 8 during the initial running-in period. H On the other hand, the low current value I L is a starting torque T that does not affect the starting performance of the electric compressor 8 after the initial running-in is completed. L generates a high current value I H When the run-in completion flag F is a value (for example, 0) indicating that the run-in operation of the electric compressor 8 is not yet completed, the start-up current selection unit 114 selects the high current value I H When the run-in completion flag F is a value (for example, 1) indicating that the run-in operation of the electric compressor 8 is completed, the low current value I L Select .

[0045] In response to an external operation command, the virtual rotor position calculation unit 115 calculates the rotor position when it is assumed that the rotor is rotating at a predetermined rotational speed ωv [rad / s], i.e., the virtual rotor position θv, at predetermined time intervals (e.g., every control period) and stores this in volatile memory. For example, the virtual rotor position θv is calculated by multiplying a predetermined rotational speed ωv set in advance by the time elapsed since the start of execution of the startup mode. Thus, unlike the rotor position θm, the virtual rotor position θv does not indicate the actual rotational angle of the rotor.

[0046] The current command value calculation unit 107 calculates the selected starting current I START Based on this, the command values ​​of the input currents of the electric motor 7 are calculated as d-axis and q-axis current command values ​​Id*, Iq* in the dq-axis rotating coordinate system. When the starting mode is executed, the current rotation speed ω of the rotor is not fed back, and the d-axis and q-axis current command values ​​Id*, Iq* are fixed values. For example, the d-axis and q-axis current command values ​​Id*, Iq* are calculated by applying the selected starting current I START (Starting torque T START ) is calculated using the value of the starting current I selected for the first and second relational expressions. The first relational expression is a relation in which the input current of the electric motor 7 is expressed by the d-axis current and the q-axis current. The second relational expression is a relation in which the output torque of the electric motor 7 is expressed by the d-axis current and the q-axis current.START (Starting torque T START ) are used, all the currents other than the d-axis and q-axis currents Id and Iq are constants. Therefore, the d-axis current command value Id* calculated as the d-axis current Id and the q-axis current command value Iq* calculated as the q-axis current command value Iq* are fixed values.

[0047] Based on the calculated d-axis and q-axis current command values ​​Id*, Iq*, the voltage command value calculation unit 108 calculates command values ​​for the voltages applied to the electric motor 7 as d-axis and q-axis voltage command values ​​Vd*, Vq* in a dq-axis rotating coordinate system. When the start-up mode is executed, the d-axis and q-axis currents Id, Iq and the current rotational speed ω of the rotor are not fed back, and the d-axis and q-axis voltage command values ​​Vd*, Vq* are fixed values. For example, the d-axis and q-axis applied voltages Vd*, Vq* are calculated using a voltage equation for the electric motor 7 in the dq-axis rotating coordinate system. In this voltage equation, the d-axis and q-axis applied voltages Vd, Vq are expressed using the d-axis and q-axis currents Id, Iq and the rotor rotational speed ω as variables, respectively. However, when the d-axis and q-axis current command values ​​Id*, Iq* are used for the d-axis and q-axis currents Id, Iq in the above voltage equation, and a predetermined rotation speed ωv is used for the rotor rotation speed ω, all the variables except the d-axis and q-axis applied voltages Vd, Vq are constants. Therefore, the d-axis voltage command value Vd* calculated as the d-axis applied voltage Vd and the q-axis voltage command value Vq* calculated as the q-axis applied voltage Vq are fixed values.

[0048] Based on the calculated virtual rotor position θv, a two-axis-to-three-phase conversion unit 109 converts the d-axis and q-axis voltage command values ​​Vd*, Vq* in the dq-axis rotating coordinate system of the rotor into three-phase voltage command values ​​Vu*, Vv*, Vw* in the three-phase stationary coordinate system of the stator.

[0049] Start determination unit 116 determines whether or not the start of electric compressor 8 has been successful, based on rotor position θm estimated by rotor position estimator 103 and virtual rotor position θv calculated by virtual rotor position calculator 115. If the start-up is determined to be successful, motor control device 10A transitions from start-up mode to sensorless mode. If the start-up is not determined to be successful within the time limit, execution of the start-up mode is attempted again.

[0050] FIG. 7 shows an example of control processing in motor control device 10A when the startup mode is executed.

[0051] In step S101, the motor control device 10A uses the starting current selection unit 114 to refer to the value of the break-in completion flag F stored in the break-in completion flag storage unit 113 to determine whether or not the break-in operation of the electric compressor 8 has been completed. If the motor control device 10A determines that the break-in operation of the electric compressor 8 has been completed (e.g., F=1) (YES), the process proceeds to step S102, where the starting current I START As a low current value I L On the other hand, if the motor control device 10A determines that the running-in of the electric compressor 8 is not yet completed (for example, F=0) (NO), the process proceeds to step S103, and the starting current I START As a high current value I H Select .

[0052] In step S104, the motor control device 10A adjusts the starting current I set in step S102 or step S103. START The forced commutation control is performed based on the value of (a). Note that the details of the forced commutation control will be omitted here, and only explanations will be given of the current command value calculation unit 107, voltage command value calculation unit 108, two-axis-to-three-phase conversion unit 109, gate signal generation unit 110, and virtual rotor position calculation unit 115, which are functions during execution of the start-up mode in the first example.

[0053] In step S105, the motor control device 10A determines whether the start-up of the electric compressor 8 was successful or not based on the virtual rotor position θv and the rotor position θm using the phase current acquisition unit 101, applied voltage acquisition unit 102, rotor position estimator 103, virtual rotor position calculator 115, and start-up determination unit 116. For example, the motor control device 10A determines that the start-up of the electric compressor 8 was successful when the deviation Δθ between the virtual rotor position θv and the rotor position θm, which was stored in the volatile memory during the forced commutation control in step S104, remains zero or is small. On the other hand, the motor control device 10A determines that the start-up of the electric compressor 8 was unsuccessful if the deviation Δθ does not remain zero or is small within the time limit after the start-up mode is initiated. If the motor control device 10A determines that the start-up of the electric compressor 8 was successful (YES), it ends the control process during the start-up mode and transitions to the sensorless mode. On the other hand, if the motor control device 10A determines that the start-up of the electric compressor 8 has failed (NO), it resets the value of the current virtual rotor position θv to zero in order to execute the start-up mode from the beginning, and returns the process to step S101.

[0054] In the motor control device 10A configured as described above, the break-in time Σt BRK When it is determined that the break-in operation of the electric compressor 8 is completed based on the above, the value of the break-in completion flag F is rewritten. Then, the motor control device 10A determines the start-up current I START Based on the value of the break-in completion flag F, the high current value I when break-in operation is not completed is set. H From the low current value I when the break-in period is complete L Therefore, the high current value I H The starting current I START Compared to when the start-up mode is executed in the normal mode, it is possible to reduce deterioration of the switching elements 91 to 96 of the motor drive circuit 9 and the mechanical sliding parts of the electric compressor 8. This makes it possible to suppress shortening of the product life and failures while taking into consideration the start-up performance during the initial running-in of the electric compressor 8.

[0055] [Second example motor control device] Next, a motor control device 10B, which is a second example of the motor control device 10 configured as described above, will be described with reference to Figures 8 and 9. When the motor control device 10B is in the startup mode, the functional configuration thereof is different from that of the motor control device 10A in that it further includes a startup time measurement unit 117 and a break-in unnecessary determination unit 118. As a result, the motor control device 10B can determine the break-in time Σt BRK When the initial running-in of the electric compressor 8 is completed before the starting current I START A low current value I L It should be noted that for motor control device 10B, a description of the functional configuration when sensorless mode is executed will be omitted, and the same functions in the functional configuration when startup mode is executed will be assigned the same reference numerals, and their description will be omitted or simplified. The same applies hereinafter.

[0056] 8 shows an example of the functional configuration of the motor control device 10B when the start-up mode is executed. When the running-in operation of the electric compressor 8 is not completed, the start-up time measurement unit 117 measures the time from when the start-up mode is started until it is determined that the start-up is successful, that is, the start-up time t START The break-in unnecessary determination unit 118 measures the start-up time t START Based on the determination result of the run-in completion determination unit 112, the run-in completion flag storage unit 113 determines whether or not a run-in operation of the electric compressor 8 is necessary. Furthermore, based on the determination result of the run-in completion determination unit 112 described above as well as the determination result of the run-in unnecessary determination unit 118, the run-in completion flag storage unit 113 rewrites the value of the run-in completion flag F as necessary and stores it in a writable nonvolatile memory such as a flash memory.

[0057] Fig. 9 shows an example of control processing when the startup mode is executed in motor control device 10B. Note that steps S201 to S205 in Fig. 9 are similar to steps S101 to S105 in Fig. 7, and therefore description thereof will be omitted.

[0058] If the motor control device 10B determines in step S205 that the start-up of the electric compressor 8 was successful, the process proceeds to step S206. In step S206, the motor control device 10B, using the start-up time measurement unit 117, references the value of the break-in completion flag F stored in the break-in completion flag storage unit 113 to determine whether the break-in operation of the electric compressor 8 has been completed. If the motor control device 10B determines that the break-in operation of the electric compressor 8 has been completed (e.g., F=1) (YES), the motor control device 10B ends the control process during startup mode execution. On the other hand, if the motor control device 10B determines that the break-in operation of the electric compressor 8 has not been completed (e.g., F=0) (NO), the process proceeds to step S207.

[0059] In step S207, the motor control device 10B calculates the startup time t START Measure this startup time t START The predetermined value b is determined based on the start-up time t START Considering that the initial running-in of the electric compressor 8 is actually completed, the start-up time t START The value is greater than 0 and is predefined based on the start-up time t START If it is determined that the start-up time t is less than the predetermined value b (YES), the process proceeds to step S208, and the value of the run-in unnecessary variable N (a positive integer) indicating the degree to which the run-in operation of the electric compressor 8 is unnecessary is incremented by 1. On the other hand, the motor control device 10B START If it is determined that is equal to or greater than the predetermined value b (NO), the control process during execution of the start-up mode is terminated.

[0060] In step S209, motor control device 10B determines whether the value of run-in no-cost variable N is equal to or greater than predetermined value c using run-in no-cost determination unit 118. If motor control device 10B determines that the value of run-in no-cost variable N is equal to or greater than predetermined value c (≧1) (YES), it determines that run-in of electric compressor 8 is not required and proceeds to step S210. On the other hand, if motor control device 10B determines that the value of run-in no-cost variable N is less than predetermined value c (NO), it determines that run-in of electric compressor 8 is required and ends the control processing during startup mode execution.

[0061] In step S210, motor control device 10B rewrites the value of run-in completion flag F from a value indicating that run-in is not complete (e.g., 0) to a value indicating that run-in is complete (e.g., 1) using run-in completion flag storage unit 113. Then, in step S211, motor control device 10B resets the value of run-in unnecessary variable N to zero, and ends the control processing when the startup mode is executed.

[0062] The value of the no-run-in variable N is held in the writable non-volatile memory until the next time the start-up mode is executed, regardless of whether it is a reset value or not.

[0063] In the motor control device 10B configured as above, the start-up time t START When the motor control device 10B determines that the initial running-in of the electric compressor 8 is complete, the motor control device 10B starts the running-in time Σt BRK Regardless of the value of I, the value of the break-in completion flag F is rewritten to a value (for example, 1) indicating that the break-in operation is complete. START High current value I H The time required for the initial running-in of the electric compressor 8 is the minimum time required for the initial running-in of the electric compressor 8. Therefore, compared to the motor control device 10A, the motor control device 10B is more advantageous in terms of achieving both the start-up performance of the electric compressor 8 during the initial running-in and the prevention of shortened product life and failures.

[0064] [Third example motor control device] Next, a motor control device 10C, which is a third example of the motor control device 10 configured as described above, will be described with reference to Figures 10 and 11. When the motor control device 10C is in the start-up mode, a start-up failure counting unit 119 and an initial break-in determination unit 120 have been added to the functional configuration of the motor control device 10C compared to the motor control device 10A. As a result, even after the break-in operation of the electric compressor 8 is completed, if the initial break-in of the electric compressor 8 is insufficient, the motor control device 10C will not increase the starting current I START A high current value I H , so that the startability of the electric compressor 8 can be ensured.

[0065] 10 shows an example of the functional configuration of motor control device 10C when the startup mode is executed. Start failure counting unit 119 increments a count value each time start determination unit 116 determines that start has failed, and stores this as the number of start failures M (a positive integer). Initial run-in determination unit 120 determines whether the initial run-in of electric compressor 8 is insufficient, based on the number of start failures M. Furthermore, run-in completion flag storage unit 113 rewrites the value of run-in completion flag F as needed, based on the determination result of initial run-in determination unit 120 in addition to the determination result of the aforementioned run-in completion determination unit 112, and stores the rewritten value in a writable non-volatile memory such as a flash memory.

[0066] Fig. 11 shows an example of control processing when the startup mode is executed in motor control device 10C. Note that steps S301 to S305 in Fig. 11 are similar to steps S101 to S105 in Fig. 7, and therefore description thereof will be omitted.

[0067] If the motor control device 10C determines in step S305 that the start-up of the electric compressor 8 has failed, the process proceeds to step S306. In step S306, the motor control device 10C uses the start-up failure counting unit 119 to refer to the value of the break-in completion flag F stored in the break-in completion flag storage unit 113 to determine whether the break-in of the electric compressor 8 has been completed. If the motor control device 10C determines that the break-in of the electric compressor 8 has been completed (e.g., F=1) (YES), the process proceeds to step S307, where the value of the number of start-up failures M is incremented by one. On the other hand, if the motor control device 10C determines that the break-in of the electric compressor 8 has not been completed (e.g., F=0) (NO), the process returns to step S301 to execute the start-up mode again.

[0068] In step S308, the motor control device 10C determines whether the initial running-in of the electric compressor 8 is insufficient, based on whether the number of start-up failures M is equal to or greater than a predetermined value d, using the initial running-in determination unit 120. If the number of start-up failures M is equal to or greater than the predetermined value d (YES), the motor control device 10C determines that the initial running-in of the electric compressor 8 is insufficient, and proceeds to step S309. On the other hand, if the number of start-up failures M is less than the predetermined value d (NO), the motor control device 10C determines that the initial running-in of the electric compressor 8 is not insufficient, and returns to step S301 to execute the startup mode again.

[0069] In step S309, motor control device 10C resets the value of break-in completion flag F to a value indicating that break-in operation is not complete (for example, 0) using break-in completion flag storage unit 113. Then, in step S310, motor control device 10C resets the value of start failure count M to zero, and returns the process to step S301 to execute the start mode again.

[0070] The value of the number of startup failures M may be stored in a writable non-volatile memory, or may be reset at the end of the startup mode if the break-in completion flag F is not reset after one execution of the startup mode.

[0071] In the motor control device 10C configured as described above, after the break-in operation of the electric compressor 8 is completed, it monitors whether the initial break-in of the electric compressor 8 is insufficient based on the number of start-up failures M. When the motor control device 10C determines that the initial break-in of the electric compressor 8 is insufficient, it resets the value of the break-in completion flag F to a value (for example, 0) indicating that the break-in operation is not completed, and reduces the starting current I START A high current value I H to ensure the start-up performance of the electric compressor 8. Therefore, the motor control device 10C not only has the effect of suppressing shortening of the product life and failures like the motor control device 10A, but also has an advantage over the motor control device 10A in terms of the start-up performance of the electric compressor 8 in particular.

[0072] The present invention has been specifically described above with reference to preferred embodiments. However, various modifications can be made based on the basic technical concept and teachings of the present invention, as follows.

[0073] In the above embodiment, the starting current I START is a high current value I H and low current value I L Instead of the two values ​​selected, three or more different current values ​​can be selected. In this case, the break-in time Σt BRK As the starting current I increases between zero and the predetermined value a, the value of the break-in completion flag F is rewritten two or more times, and each value of the break-in completion flag F becomes a different value. START The current value selected as the break-in time Σt is set to a different value for each value of the break-in completion flag F. BRK As the value of the break-in completion flag F changes with the increase of H to low current value I L It decreases in multiple stages to

[0074] In the above embodiment, the starting current I START was selected based on the value of the break-in completion flag F, but instead, the starting current I STARTmay be determined without using the break-in completion flag F. For example, the break-in time Σt BRK For the starting current I START By using a function that continuously changes the current value of BRK The current value corresponding to the low current value I L and high current value I H The difference between the high current value I and the low current value I is divided by a predetermined value a. H A linear decreasing function with an intercept of I can be used. START The current value selected as the break-in time Σt BRK As the current I increases, H to low current value I L continuously decreases to

[0075] In the motor control device 10B, when the value of the no-run-in variable N is equal to or greater than a predetermined value c, the run-in completion flag F is rewritten from a value (e.g., 0) indicating that the run-in is not yet complete to a value (e.g., 1) indicating that the run-in is complete. Alternatively, if the predetermined value c is set to an integer equal to or greater than 3, the value of the run-in completion flag F may be rewritten to two or more different values ​​as the value of the no-run-in variable N increases from zero to the predetermined value c. Starting current I START The current value selected as the high current value I is set to a different value for each value of the break-in completion flag F, and as the value of the break-in completion flag F changes with the increase of the break-in unnecessary variable N, H to low current value I L It decreases in multiple stages to

[0076] In addition, in the motor control device 10B, the starting current I START is set without using the break-in completion flag F, and the start time t START As the starting current I decreases from a predetermined value b, START A high current value I H to low current value I L For example, the start time t START For the starting current I STARTBy using a function that continuously changes the current value of START It is possible to calculate a current value that corresponds one-to-one to the above.

[0077] In the motor control device 10C, when the value of the number of start-up failures M is equal to or greater than the predetermined value d, the break-in completion flag F is reset to zero. Alternatively, if the predetermined value d is set to an integer equal to or greater than 3, the value of the break-in completion flag F may be rewritten to different values ​​two or more times as the value of the number of start-up failures M increases from zero to the predetermined value d. Starting current I START The current value selected as the low current value I is set to a different value for each value of the break-in completion flag F, and as the value of the break-in completion flag F changes with the increase in the number of start failures M, L to high current value I H It increases in multiple stages.

[0078] In the above embodiment, in order to determine whether the electric motor 7 is being driven in a manner that is effective for the initial running-in of the electric compressor 8, the criteria are that at least one of the torque generated by the electric motor 7 and the current flowing through the electric motor 7 is equal to or greater than the respective threshold values. Alternatively or in addition to this, the rotational speed ω of the rotor may be used. For example, BRK In order to add the control period Δt in the calculation of (a), it is possible to use the rotor rotation speed ω being equal to or higher than a predetermined speed as a criterion. In other words, it is possible to determine whether the electric motor 7 is being driven in a manner that is effective for the initial running-in of the electric compressor 8, based on whether at least one of the torque generated by the electric motor 7, the magnitude of the current flowing through the electric motor 7, and the rotation speed ω of the electric motor 7 is equal to or higher than a threshold value defined for each of the generated torque, the magnitude of the current, and the rotation speed ω.

[0079] As described above, the refrigeration cycle 1 may be applied to a vehicle air conditioner. In this case, the motor control device 10 may be housed in the engine compartment together with the electric compressor 8 incorporated in the refrigeration cycle 1. Such a motor control device 10 can control the drive of the electric motor 7 by receiving an operation command from an HVAC (Heating, Ventilation, and Air Conditioning) controller that controls an HVAC unit in the vehicle cabin. Communication between the motor control device 10 and the HVAC controller is performed via an in-vehicle network such as a Controllable Area Network (CAN) or a Local Interconnect Network (LIN). The values ​​of the break-in completion flag F, the break-in no-required variable N, and the number of start-up failures M may be held in a writable non-volatile memory of the HVAC controller and transmitted to the motor control devices 10A-10C as necessary.

[0080] In the sensorless mode, motor control devices 10A to 10C share common functions except for break-in time calculation unit 111, break-in completion determination unit 112, and break-in completion flag storage unit 113. These common functions are provided as an example to realize a drive mode in which current supply to a stator coil is controlled by sensorlessly detecting the rotor position based on an induced voltage generated in the stator coil; however, such a drive mode may be realized by other methods. For example, current command value calculation unit 107 can calculate a command value for an input current to electric motor 7 as a current peak command value and a current phase command value. In this case, voltage command value calculation unit 108 can calculate a command value for a voltage applied to electric motor 7 based on the deviation between the current peak value calculated by rotor position estimator 103 and the current peak command value, and the deviation between the current phase calculated by rotor position estimator 103 and the current phase command value.

[0081] Furthermore, the start-up modes of motor control devices 10A to 10C share common functions, except for run-in completion flag storage unit 113, start-up current selection unit 114, start-up time measurement unit 117, run-in no-necessity determination unit 118, start-up failure counting unit 119, and initial run-in determination unit 120. These common functions are provided as an example to realize a start-up mode in which electric motor 7 is driven by forced commutation to determine whether or not starting of electric compressor 8 is successful, and such a start-up mode may be realized by other methods. For example, current command value calculation unit 107 can uniquely calculate an input current command value for electric motor 7 that corresponds to a set current peak value included in an operation command or pre-stored in motor control devices 10A to 10C by referring to a predetermined table that associates current peak values ​​with input currents to electric motor 7.

[0082] The technical concepts and modifications based thereon described in the above embodiments can be combined as appropriate as long as no contradictions arise. For example, the functional configuration of the motor control device 10B when it is in the startup mode may include the start-up failure counting unit 119 and the initial break-in determination unit 120 of the motor control device 10C. Due to manufacturing tolerances and the like, the time required for the initial break-in to be completed varies from one electric compressor 8 to another. However, by combining a part of the motor control device 10C with the motor control device 10B as described above, the break-in time Σt BRK It is also possible to deal with the excess or deficiency of the initial break-in by determining the completion time of the break-in based on the break-in time Σt BRK Even if the initial break-in is sufficient, the starting current I START A low current value I L This can prevent a decrease in product life and failures. BRK Even if the initial break-in is insufficient even if the value is greater than the predetermined value a, the starting current I START again at a high current value I H As a result, the start-up performance of the electric compressor 8 can be improved. [Explanation of symbols]

[0083] 3... compressor, 7... electric motor, 8... electric compressor, 10, 10A, 10B, 10C... motor control device, 71... U-phase coil (stator coil), 72... V-phase coil (stator coil), 73... W-phase coil (stator coil), I START ...starting current, I H …High current value (first current value), I L ...low current value (second current value), Iu...U phase current, Iv...V phase current, Iw...W phase current, M...number of start failures, t START …starting time, θm…rotor position, Σt BRK …break-in time, ω…rotation speed

Claims

1. A control device for an electric compressor that executes a sensorless mode in which a rotor position of an electric motor provided as a power source of the electric compressor is detected without a sensor to control energization of a stator coil, when the sensorless mode is executed, it is determined whether or not a break-in operation of the electric compressor has been completed based on a time period during which drive of the electric motor becomes effective for an initial break-in of the electric compressor, and when it is determined that the break-in operation has not been completed, information indicating that the break-in operation has not been completed is stored, and when it is determined that the break-in operation has been completed, the information indicating that the break-in operation has not been completed is rewritten to information indicating that the break-in operation has been completed; a control device for an electric compressor, when executing a startup mode as a preliminary stage of the sensorless mode, setting the startup current to a first current value if information indicating that the break-in operation is incomplete is stored, and setting the startup current to a second current value lower than the first current value if information indicating that the break-in operation is completed is stored.

2. 2. The electric compressor control device according to claim 1, wherein the time during which driving of the electric motor is effective for initial running-in of the electric compressor is an integrated value of time during which at least one of the torque generated by the electric motor, the magnitude of the current flowing through the electric motor, and the rotational speed of the electric motor is equal to or greater than a threshold value defined for each of the generated torque, the magnitude of the current, and the rotational speed.

3. 3. The control device for an electric compressor according to claim 1, wherein, when information indicating that the break-in operation is incomplete is stored, the first current value is reduced based on a start-up time from when the start mode is started until the start-up of the electric compressor is successful, with the second current value as a lower limit value.

4. 4. The control device for an electric compressor according to claim 1, wherein, when information indicating completion of the break-in operation is stored, the second current value is increased based on the number of times startup of the electric compressor fails during execution of the startup mode, with the first current value as an upper limit value.

5. 3. The control device for an electric compressor according to claim 1, wherein the first current value is configured with a plurality of values ​​that decrease stepwise or continuously as a time during which driving of the electric motor is effective for an initial running-in of the electric compressor increases.

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