JP6217667B2 - Electric compressor - Google Patents

Description

  The present invention relates to an electric compressor.

  For example, as shown in Patent Document 1, an electric compressor includes a compression unit that compresses and discharges a refrigerant, an electric motor that drives the compression unit, and a drive circuit that drives the electric motor. There is a case.

  Patent Document 2 describes, for example, pulse width modulation control (PWM control) as a control method of a drive circuit that drives an electric motor. In the pulse width modulation control, a control signal is generated by a voltage command signal for instructing a voltage and a carrier wave signal, and ON / OFF control of a switching element provided in the drive circuit is performed based on the control signal. Thereby, direct-current power is converted into alternating current power in a drive circuit. Then, when the AC power is input to the electric motor, the electric motor is driven. Further, Patent Document 2 describes that there are a three-phase modulation method and a two-phase modulation method as the modulation method of the drive circuit, and that the modulation method is switched according to the temperature of the drive circuit.

JP 2005-201108 A JP 2011-109803 A

  Here, the temperature of the drive circuit may become excessively high depending on the operation state of the drive circuit and the surrounding conditions of the drive circuit. In this case, the operation of the electric motor or the electric compressor may be hindered. However, in order to prevent the temperature of the drive circuit from becoming excessively high, it is not preferable that, for example, noise increases.

  This invention is made | formed in view of the situation mentioned above, The objective is to provide the electric compressor which can suppress suitably that the temperature of a drive circuit becomes high too much.

An electric compressor that achieves the above object includes: a compression unit that compresses fluid; an electric motor that drives the compression unit; a drive circuit that drives the electric motor and includes a switching element; and Drive mode control for controlling the drive mode of the drive circuit based on a temperature grasping unit that grasps the temperature, at least one of the rotation speed and modulation rate of the electric motor, and a grasped temperature grasped by the temperature grasping unit A first drive mode in which the modulation method is a three-phase modulation method, a second drive mode in which the modulation method is a two-phase modulation method, and a carrier frequency is the first drive mode. lower than the carrier frequency, and includes a third drive mode modulation scheme is three-phase modulation scheme, wherein the drive mode control unit, the drive mode is the first operating mode In a situation, based on the fact that a two-phase modulation condition defined by at least one of the rotational speed and the modulation factor is satisfied, the drive mode is shifted from the first drive mode to the second drive mode, In the situation where the drive mode is the first drive mode, the drive mode is changed from the first drive mode to the first drive mode based on the grasped temperature becoming higher than a predetermined third drive mode transition trigger temperature. The drive mode control unit is configured to shift to a third drive mode, and in the situation where the drive mode is the first drive mode, the two-phase modulation condition is satisfied, and the grasped temperature is When the temperature is higher than the third drive mode transition trigger temperature, the drive mode is shifted from the first drive mode to the second drive mode .
An electric compressor that achieves the above object includes: a compression unit that compresses fluid; an electric motor that drives the compression unit; a drive circuit that drives the electric motor and includes a switching element; and Drive mode control for controlling the drive mode of the drive circuit based on a temperature grasping unit that grasps the temperature, at least one of the rotation speed and modulation rate of the electric motor, and a grasped temperature grasped by the temperature grasping unit A first drive mode in which the modulation method is a three-phase modulation method, a second drive mode in which the modulation method is a two-phase modulation method, and a carrier frequency is the first drive mode. A third drive mode having a lower frequency than a carrier frequency and a modulation method being a three-phase modulation method, wherein the drive mode control unit is configured such that the drive mode is the first drive mode In a situation, based on the fact that a two-phase modulation condition defined by at least one of the rotational speed and the modulation factor is satisfied, the drive mode is shifted from the first drive mode to the second drive mode, In the situation where the drive mode is the first drive mode, the drive mode is changed from the first drive mode to the first drive mode based on the grasped temperature becoming higher than a predetermined third drive mode transition trigger temperature. The drive mode control unit is configured to shift to a third drive mode, and in the situation where the drive mode is the first drive mode, the two-phase modulation condition is satisfied, and the grasped temperature is When the temperature is higher than the third drive mode transition trigger temperature, the drive mode is shifted from the first drive mode to the third drive mode.

According to each said structure, a drive circuit can be driven in the drive mode according to a condition by controlling a drive mode based on at least one of the rotation speed and modulation rate of an electric motor, and grasping | ascertain temperature. Therefore, it is possible to suitably suppress the temperature of the drive circuit from becoming excessively high.

Specifically, based on the fact that the two-phase modulation condition is satisfied in the situation where the drive mode is the first drive mode, the power in the drive circuit is changed by shifting the drive mode from the first drive mode to the second drive mode. Loss and heat generation can be reduced.

  Further, in the situation where the drive mode is the first drive mode, the drive mode shifts from the first drive mode to the third drive mode based on the grasped temperature becoming higher than the third drive mode transition trigger temperature. Since the carrier frequency of the third drive mode is lower than the carrier frequency of the first drive mode, the power loss of the drive circuit tends to be smaller in the third drive mode than in the first drive mode. Thereby, since the emitted-heat amount of a drive circuit can be made small, the heat_generation | fever of a drive circuit can be suppressed.

The electric compressor includes a field weakening control unit that performs field weakening control on the electric motor when a predetermined field weakening condition is satisfied, and the third drive mode transition trigger temperature is the first first 3 drive mode transition trigger temperature, the drive mode control unit based on the fact that a predetermined third drive mode transition condition is satisfied in a situation where the drive mode is the second drive mode The mode is shifted from the second drive mode to the third drive mode, and the third drive mode transition condition is that the grasping temperature is higher than a second third drive mode transition trigger temperature at which the grasped temperature is predetermined. a high Ri, and is that the field weakening control by the field weakening control unit is not performed, the second of the third drive mode transition trigger temperature, said first third drive motor Higher and better than de transition triggered by temperature. According to this configuration, the second third drive mode transition trigger temperature used for the transition condition from the second drive mode to the third drive mode is used for the transition condition from the first drive mode to the third drive mode. It is higher than the first third drive mode transition trigger temperature. As a result, in the first drive mode in which the amount of heat generated by the drive circuit is likely to be larger than that in the second drive mode, the transition to the third drive mode is performed relatively early, so that an increase in the temperature of the drive circuit can be dealt with early. . On the other hand, the second drive mode can be maintained for a relatively long time.

Further , according to this configuration, when the field weakening condition is satisfied, desired electric power can be input to the electric motor by performing field weakening control.

  Here, in the field weakening control, the amount of heat generated by the drive circuit is likely to be small as compared with the control of the normal electric motor. For this reason, the heat generation amount of the drive circuit when the drive mode is the second drive mode and the field weakening control is performed is equal to or smaller than the heat generation amount of the drive circuit in the third drive mode. obtain. In this regard, according to this configuration, when the driving mode is the second driving mode and the field weakening control is performed, the grasping temperature is higher than the second third driving mode transition trigger temperature. Even if there is, the drive mode does not shift from the second drive mode to the third drive mode. Thereby, it is possible to suppress unnecessary transition of the drive mode.

With respect to the electric compressor, the drive mode control unit is based on the fact that the grasped temperature becomes lower than a predetermined first drive mode transition trigger temperature in a situation where the drive mode is the third drive mode. The drive mode is shifted from the third drive mode to the first drive mode, and in the situation where the drive mode is the third drive mode, the grasping temperature is a predetermined second drive mode transition trigger temperature. And the transition of the drive mode from the third drive mode to the second drive mode based on the fact that the two-phase modulation condition is satisfied, and the transition to the first drive mode. trigger temperature, the rather low than the second driving mode transition trigger temperature, the drive mode control unit, in a situation wherein the drive mode is the third driving mode, before When the grasping temperature is lower than the first drive mode transition trigger temperature, and when the grasping temperature is lower than the second drive mode transition trigger temperature and the two-phase modulation condition is satisfied, The drive mode may be shifted from the third drive mode to the second drive mode . According to this configuration, in the situation where the drive mode is the third drive mode, when the grasping temperature is lower than the second drive mode transition trigger temperature and the two-phase modulation condition is satisfied, the drive mode is The mode shifts from the 3 drive mode to the second drive mode. Thereby, since it is possible to shift the drive mode from the third drive mode to the second drive mode without going through the first drive mode, it is possible to avoid unnecessary shift of the drive mode. In addition, since the first drive mode transition trigger temperature is set lower than the second drive mode transition trigger temperature, the first drive mode in which the heat generation amount of the drive circuit is relatively large is sufficiently increased. By shifting after the temperature decreases, the temperature rise of the drive circuit can be suppressed, while the second drive mode in which the amount of heat generated by the drive circuit is relatively small can be shifted relatively early.

  According to this invention, it can suppress suitably that the temperature of a drive circuit becomes high too much.

The schematic diagram which shows the outline | summary of an electric compressor and a vehicle air conditioner. The circuit diagram of an inverter. The conceptual diagram for demonstrating drive mode. The flowchart which shows the drive mode switching control process performed in a drive mode control part. The correlation diagram for demonstrating the switching aspect of a drive mode.

Hereinafter, an embodiment of the electric compressor will be described. The electric compressor of this embodiment is mounted on a vehicle, for example, and used for a vehicle air conditioner.
As shown in FIG. 1, the vehicle air conditioner 100 includes an electric compressor 10 and an external refrigerant circuit 101 that supplies refrigerant to the electric compressor 10. The external refrigerant circuit 101 has, for example, a heat exchanger and an expansion valve. The vehicle air conditioner 100 cools and heats the interior of the vehicle by compressing the refrigerant by the electric compressor 10 and performing heat exchange and expansion of the refrigerant by the external refrigerant circuit 101.

  The vehicle air conditioner 100 includes an air conditioning ECU 102 that controls the entire vehicle air conditioner 100. The air conditioning ECU 102 is configured to be able to grasp the in-vehicle temperature, the set temperature, and the like, and transmits various commands such as an ON / OFF command to the electric compressor 10 based on these parameters.

  The electric compressor 10 includes a housing 11 in which a suction port 11 a into which a refrigerant is sucked from an external refrigerant circuit 101 is formed, and a compression unit 12 and an electric motor 13 housed in the housing 11.

  The housing 11 has a substantially cylindrical shape as a whole, and is formed of a material having heat conductivity (for example, a metal such as aluminum). The housing 11 has a discharge port 11b through which a refrigerant is discharged.

  The compression unit 12 compresses the refrigerant sucked into the housing 11 from the suction port 11a and discharges the compressed refrigerant from the discharge port 11b. In addition, the specific structure of the compression part 12 is arbitrary, such as a scroll type, a piston type, and a vane type.

  The electric motor 13 drives the compression unit 12. The electric motor 13 includes, for example, a columnar rotating shaft 21 that is rotatably supported with respect to the housing 11, a cylindrical rotor 22 that is fixed to the rotating shaft 21 and has a permanent magnet embedded therein, and the housing 11. And a stator 23 fixed to. The axial direction of the rotating shaft 21 and the axial direction of the cylindrical housing 11 coincide with each other. The stator 23 includes a cylindrical stator core 24 and a coil 25 wound around teeth formed on the stator core 24. The rotor 22 and the stator 23 face each other in the radial direction of the rotating shaft 21.

  As shown in FIG. 1, the electric compressor 10 includes an inverter unit 30 having an inverter 31 as a drive circuit for driving the electric motor 13 and a case 32 in which the inverter 31 is accommodated. The coil 25 of the electric motor 13 and the inverter 31 are connected by a connector or the like (not shown). The case 32 is fixed to the housing 11 by a bolt 41 as a fixing tool. That is, the inverter 31 is integrated with the electric compressor 10 of the present embodiment.

  For example, the inverter 31 includes a circuit board 51 and a power module 52 electrically connected to the circuit board 51. Various electronic components and wiring patterns are mounted on the circuit board 51, for example, a temperature sensor 53 as a temperature measuring unit that measures the temperature of the circuit board 51 is mounted. A connector 54 is provided on the outer surface of the case 32, and the circuit board 51 and the connector 54 are electrically connected. Power is supplied to the inverter 31 from a DC power source E as an external power source via the connector 54, and the air conditioning ECU 102 and the inverter 31 are electrically connected.

  As shown in FIG. 2, the coil 25 of the electric motor 13 has a three-phase structure including, for example, a u-phase coil 25u, a v-phase coil 25v, and a w-phase coil 25w. That is, the electric motor 13 is a three-phase motor. Each coil 25u-25w is Y-connected, for example.

  The power module 52 includes u-phase power switching elements Qu1 and Qu2 corresponding to the u-phase coil 25u, v-phase power switching elements Qv1 and Qv2 corresponding to the v-phase coil 25v, and w-phase power switching corresponding to the w-phase coil 25w. Elements Qw1 and Qw2 are provided. That is, the inverter 31 is a so-called three-phase inverter.

  Each power switching element Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 (hereinafter simply referred to as each power switching element Qu1-Qw2) is configured by, for example, an IGBT. Each power switching element Qu1-Qw2 operates normally when the temperature of each power switching element Qu1-Qw2 is equal to or lower than a predetermined operation upper limit temperature Tmax. That is, the operation upper limit temperature Tmax is the upper limit value of the operation guarantee range of each power switching element Qu1 to Qw2, in other words, the upper limit value of the operation guarantee range of the inverter 31.

  The u-phase power switching elements Qu1 and Qu2 are connected to each other in series via a connection line, and the connection line is connected to the u-phase coil 25u. And direct-current power from DC power supply E is input into the serial connection body of each u phase power switching element Qu1, Qu2. The other power switching elements Qv1, Qv2, Qw1, and Qw2 are connected in the same manner as the u-phase power switching elements Qu1 and Qu2, except that the corresponding coils are different. .

  The inverter 31 has a smoothing capacitor C1 connected in parallel to the DC power source E. Further, the power module 52 includes freewheeling diodes Du1 to Dw2 connected in parallel to the power switching elements Qu1 to Qw2.

  The electric compressor 10 includes a control unit 55 that controls the inverter 31 (specifically, the switching operation of each of the power switching elements Qu1 to Qw2). The control unit 55 is connected to the gates of the power switching elements Qu1 to Qw2. The control unit 55 drives, that is, rotates the electric motor 13 by periodically turning on / off each of the power switching elements Qu1 to Qw2.

  Incidentally, in this embodiment, the control unit 55 employs a bootstrap system in order to turn on the power switching elements Qu1, Qv1, and Qw1 of the upper arm. Specifically, a bootstrap circuit 61 having a capacitor 61a is provided between each power switching element Qu1, Qv1, Qw1 of the upper arm and the control unit 55. The bootstrap circuit 61 generates a voltage higher than the power supply voltage that is the voltage of the DC power supply E. The control unit 55 applies the voltage generated by the bootstrap circuit 61 to the gates of the power switching elements Qu1, Qv1, Qw1 of the upper arm, thereby turning the power switching elements Qu1, Qv1, Qw1 on. To do.

  The control unit 55 performs pulse width modulation control (PWM control) on the inverter 31. Specifically, the control unit 55 generates a control signal using the carrier signal (carrier wave signal) and the command voltage value signal (comparison target signal). And the control part 55 converts direct-current power into alternating current power by performing ON / OFF control of each power switching element Qu1-Qw2 using the produced | generated control signal. The converted AC power is input to the electric motor 13 to drive the electric motor 13.

  Here, the control unit 55 is configured to be able to change the carrier frequency f which is the frequency of the carrier signal. The specific waveform of the carrier signal is arbitrary, for example, a triangular wave or a sawtooth wave.

  Further, the control unit 55 can variably control the ON / OFF duty ratio of each of the power switching elements Qu1 to Qw2 by controlling the control signal, thereby controlling the rotation speed r of the electric motor 13. Can do. When the control unit 55 is electrically connected to the air conditioning ECU 102 and receives information on the command value of the rotation speed r from the air conditioning ECU 102, the control unit 55 rotates the electric motor 13 at the rotation speed r corresponding to the command value. . In the following description, the rotational speed r of the electric motor 13 is simply referred to as the rotational speed r.

  Furthermore, the control unit 55 can control the modulation factor M, which is the ratio between the power supply voltage and the amplitude of the AC voltage output from the inverter 31, by controlling the control signal. The control unit 55 grasps the power supply voltage and the required voltage that is a voltage corresponding to the required power required for driving the electric motor 13, and makes the output voltage of the inverter 31 correspond to the power supply voltage so as to be the required voltage. To control the modulation factor M.

  The control unit 55 grasps the inverter temperature T that is the temperature of the inverter 31 based on the measurement result of the temperature sensor 53. Specifically, the temperature sensor 53 transmits the measurement result to the control unit 55. The control unit 55 has data relating to the correlation between the measurement result of the temperature sensor 53 and the temperature of the power module 52 (specifically, each of the power switching elements Qu1 to Qw2). By referring to the data, The temperature of the power module 52 corresponding to the measurement result of the sensor 53 is derived, and the derived temperature is set as the inverter temperature T. That is, the temperature sensor 53 is used to grasp the inverter temperature T. The inverter temperature T corresponds to the “grasping temperature”, and the control unit 55 corresponds to the “temperature grasping unit”.

  The inverter temperature T is not limited to the above, and may be any temperature as long as the temperature is related to the inverter 31. For example, the measured value measured by the temperature sensor 53, that is, the temperature of the circuit board 51 may be used.

  Further, the control unit 55 estimates the counter electromotive force generated in the electric motor 13 based on the applied voltage of the electric motor 13 and the current flowing through the electric motor 13, and based on the estimated counter electromotive force, A position grasping unit 62 for grasping the rotational position is provided. The control unit 55 performs ON / OFF control of the power switching elements Qu <b> 1 to Qw <b> 2 based on the rotational position of the rotor 22 grasped by the position grasping unit 62. In addition, although the structure which detects the electric current which flows into the electric motor 13 is arbitrary, the structure etc. which provide the shunt resistance, for example, detect the voltage of the said shunt resistance, and estimate the said electric current based on the detection result are considered. .

  As shown in FIG. 2, the control unit 55 includes a drive mode control unit 63 that controls the drive mode of the inverter 31 (hereinafter simply referred to as drive mode). The drive mode will be described in detail below.

  In the present embodiment, as shown in FIG. 3, the drive mode includes a first drive mode in which the carrier frequency f is the first carrier frequency f1 and the modulation method is a three-phase modulation method, and the carrier frequency f is There is a second drive mode in which the second carrier frequency is f2 and the modulation method is a two-phase modulation method. Further, the drive mode includes a third drive mode in which the carrier frequency f is the third carrier frequency f3 and the modulation method is a three-phase modulation method.

  Here, in the present embodiment, the three-phase modulation method is a drive mode in which the cyclic switching of all-phase power switching elements Qu1 to Qw2 is always performed. The two-phase modulation method is a drive mode in which the periodic ON / OFF of the power switching element of any phase among the power switching elements Qu1 to Qw2 of all phases is sequentially stopped every predetermined period (phase angle). . That is, in the two-phase modulation method, the periodic ON / OFF of any one phase of the three-phase power switching elements is stopped in turn, while the other two-phase power switching elements are periodically turned on / off. This is a drive mode in which the OFF is performed. The state where the periodic ON / OFF of the power switching element is stopped is a state where the power switching element is fixed in the ON state or the OFF state.

  In the two-phase modulation method, the ON / OFF frequency of each of the power switching elements Qu1 to Qw2 is lower than that in the three-phase modulation method. For this reason, the power loss and the heat generation amount of the inverter 31 are likely to be larger in the three-phase modulation method than in the two-phase modulation method. In the following description, unless otherwise specified, the power loss and the heat generation amount mean the power loss and the heat generation amount of the inverter 31.

  Note that the two-phase modulation method of the present embodiment uses, for example, each of the upper arm power switching elements Qu1, Qv1, Qw1 and each of the lower arm power switching elements Qu2, Qv2, Qw2. In this way, the power switching elements Qu1 to Qw2 are to be stopped.

  In the present embodiment, the first carrier frequency f1 and the second carrier frequency f2 are set to be the same. On the other hand, the third carrier frequency f3 is set lower than the first carrier frequency f1. Specifically, as shown in FIG. 3, the first carrier frequency f1 and the second carrier frequency f2 are set to 20 kHz, for example, and the third carrier frequency f3 is set to 10 kHz, for example. The first carrier frequency f1 corresponds to the “carrier frequency in the first driving mode”.

  As shown in FIG. 2, the control unit 55 includes a field weakening control unit 64 that performs field weakening control on the electric motor 13 when a predetermined field weakening condition is satisfied. The field weakening condition is, for example, that the back electromotive force generated in the electric motor 13 becomes equal to the power supply voltage.

  The field weakening control is a kind of control mode of the electric motor 13. The field weakening control is opposite to the magnetic flux generated in the permanent magnet embedded in the rotor 22 by causing a current to flow through the coils 25u to 25w of the stator 23 when the back electromotive force becomes equal to the power supply voltage. This is a control for reducing the back electromotive force by generating a magnetic flux of.

  Here, the field weakening control is executed when the modulation method is a two-phase modulation method and overmodulation control is performed. In overmodulation control, the power switching element to be operated may be maintained in the ON state for a predetermined period longer than the carrier cycle. Moreover, the situation where the field weakening control is performed is a situation where the power supply voltage is relatively low. For this reason, in the field weakening control, the power loss is likely to be smaller than in the normal control.

  The power switching element to be operated is a power switching element other than the stationary phase power switching element. In the following description, those that are not particularly described, such as field weakening control, are assumed to be normal control (in other words, non-field weakening control).

  In such a configuration, the magnitude of the power loss and the amount of heat generated in the normal control is such that the first drive mode> the second drive mode> the third drive mode. The first drive mode is a drive mode that generates the largest amount of heat among the three drive modes. The third drive mode is a drive mode that generates the smallest amount of heat among the three drive modes in at least normal control. However, in the third drive mode, noise is likely to increase as the carrier frequency f is lower.

  Here, the drive mode control unit 63 sets the drive mode to the first drive mode when the electric compressor 10 (specifically, the electric motor 13) is started. That is, in the present embodiment, the first drive mode is the initial drive mode. The drive mode control unit 63 is configured to be able to grasp the current drive mode.

  Thereafter, the drive mode control unit 63 switches the drive mode based on the inverter temperature T, the rotational speed r of the electric motor 13, and the modulation factor M during operation of the electric compressor 10 (during rotation of the electric motor 13). The drive mode switching control process is periodically executed. The drive mode switching control process will be described in detail below.

  As shown in FIG. 4, the drive mode control unit 63 determines whether or not the current drive mode is the first drive mode in step S101. When the current drive mode is not the first drive mode, the drive mode control unit 63 proceeds to step S106, whereas when the current drive mode is the first drive mode, the drive mode control unit 63 proceeds to step S102 and proceeds to the second drive mode. It is determined whether or not the transition condition to is satisfied. Specifically, in step S102, the drive mode control unit 63 determines whether a predetermined two-phase modulation condition is satisfied.

  The two-phase modulation condition is a condition determined by the restriction of the inverter 31. In the present embodiment, the two-phase modulation condition is a condition defined by at least one of the rotation speed r and the modulation factor M. Specifically, in the two-phase modulation condition, the rotation speed r is equal to or higher than a predetermined threshold rotation speed rth, and the modulation rate M is equal to or higher than a predetermined threshold modulation rate Mth.

  Here, the threshold rotation speed rth is arbitrary as long as it is a predetermined value, but is set based on the capacitance of the capacitor 61a of the bootstrap circuit 61, for example. Specifically, in the case of the two-phase modulation method using both the upper arm and the lower arm, one of the upper arm power switching elements Qu1, Qv1, and Qw1 is set over a specific period (for example, a period of 60 degrees electrical angle). It is necessary to maintain the ON state. The specific period becomes longer as the rotational speed r becomes lower. On the other hand, the sustainable period during which the power switching elements Qu1, Qv1, and Qw1 of the upper arm can be maintained in the ON state depends on the capacitance of the capacitor 61a. In this case, depending on the combination of the capacitance of the capacitor 61a and the rotation speed r, the specific period may be longer than the sustainable period. For this reason, the threshold rotation speed rth is set such that the specific period corresponding to the threshold rotation speed rth is the same as or slightly shorter than the sustainable period.

  The threshold modulation rate Mth is arbitrary as long as it is a predetermined value, but is set based on, for example, the specifications (for example, delay time) of the power switching elements Qu1 to Qw2.

  When the two-phase modulation condition is satisfied, that is, when the rotation speed r is greater than or equal to the threshold rotation speed rth and the modulation factor M is greater than or equal to the threshold modulation factor Mth, the drive mode control unit 63 performs step S103. Then, the drive mode is shifted from the first drive mode to the second drive mode, and the drive mode switching control process is terminated.

  On the other hand, when the two-phase modulation condition is not satisfied, the drive mode control unit 63, that is, either the rotation speed r is less than the threshold rotation speed rth or the modulation rate M is less than the threshold modulation rate Mth. If either is satisfied, a negative determination is made in step S102, and the process proceeds to step S104. In step S104, the drive mode control unit 63 determines whether a condition for shifting to the third drive mode is satisfied. Specifically, the drive mode control unit 63 grasps the inverter temperature T from the measurement result of the temperature sensor 53, and whether or not the inverter temperature T is higher than a predetermined first third drive mode transition trigger temperature Tu1. Determine whether. The first third drive mode transition trigger temperature Tu1 is lower than the operation upper limit temperature Tmax, for example, 70 ° C.

  When the inverter temperature T is equal to or lower than the first third drive mode transition trigger temperature Tu1, the drive mode control unit 63 ends the drive mode switching control process as it is. On the other hand, when the inverter temperature T is higher than the first third drive mode transition trigger temperature Tu1, the drive mode control unit 63 changes the drive mode from the first drive mode to the third drive mode in step S105. Then, the drive mode switching control process is terminated.

  Incidentally, in the present embodiment, the drive mode control unit 63 executes the process of step S102 before executing the process of step S104. For this reason, in the situation where the drive mode is the first drive mode, the drive mode control unit 63 sets the transition condition to the second drive mode (two-phase modulation condition) and the transition condition to the third drive mode (T> Tu1). ), The shift to the second drive mode is prioritized over the shift to the third drive mode.

  As shown in FIG. 4, in step S106, the drive mode control unit 63 determines whether or not the current drive mode is the second drive mode. If the current drive mode is not the second drive mode, the drive mode control unit 63 proceeds to step S111. If the current drive mode is the second drive mode, the drive mode control unit 63 proceeds to step S107, and the third drive mode. It is determined whether or not the transition condition to is satisfied. Specifically, the drive mode control unit 63 determines whether or not the inverter temperature T is higher than a predetermined second third drive mode transition trigger temperature Tu2 and the field-weakening control is not being performed. The second third drive mode transition trigger temperature Tu2 is set higher than the first third drive mode transition trigger temperature Tu1 within a range lower than the operation upper limit temperature Tmax (Tmax> Tu2> Tu1). For example, 90 ° C.

  When the inverter temperature T is higher than the second third drive mode transition trigger temperature Tu2 and the field-weakening control is not being performed (that is, normal control is being performed), the drive mode control unit 63 proceeds to step S108 to drive The mode is shifted from the second drive mode to the third drive mode, and the drive mode switching control process is terminated.

  On the other hand, if the inverter temperature T is equal to or lower than the second third drive mode transition trigger temperature Tu2 or the field weakening control is being performed, the drive mode control unit 63 makes a negative determination in step S107 and proceeds to step S109. Then, it is determined whether or not the condition for shifting to the first drive mode is satisfied. Specifically, in step S109, the drive mode control unit 63 determines whether the two-phase modulation condition is not satisfied. If the two-phase modulation condition is satisfied, the drive mode control unit 63 makes a negative determination in step S109 and ends the drive mode switching control process as it is. On the other hand, if the two-phase modulation condition is not satisfied, the drive mode control unit 63 makes an affirmative determination in step S109, and shifts the drive mode from the second drive mode to the first drive mode in step S110. Then, the drive mode switching control process is terminated. That is, the drive mode control unit 63 shifts the drive mode from the second drive mode to the first drive mode based on the fact that the two-phase modulation condition is not satisfied in the situation where the drive mode is the second drive mode. Let

  If the current drive mode is not the first drive mode and not the second drive mode (step S101: NO, step S106: NO), it means that the current drive mode is the third drive mode. In this case, the drive mode control unit 63 determines whether or not the condition for shifting to the second drive mode is satisfied in step S111. Specifically, in step S111, the drive mode control unit 63 determines whether or not the inverter temperature T is lower than the predetermined second drive mode transition trigger temperature Td2 and the two-phase modulation condition is satisfied. To do. The second drive mode transition trigger temperature Td2 is set lower than the second third drive mode transition trigger temperature Tu2, and is 85 ° C., for example.

  If the inverter temperature T is lower than the second drive mode transition trigger temperature Td2 and the two-phase modulation condition is satisfied, the drive mode control unit 63 sets the drive mode to the third drive mode in step S112. Is shifted to the second drive mode, and the drive mode switching control process is terminated.

  On the other hand, when the inverter temperature T is equal to or higher than the second drive mode transition trigger temperature Td2, or when the two-phase modulation condition is not satisfied, the drive mode control unit 63 makes a negative determination in step S111 and performs step S113. Then, it is determined whether or not the condition for shifting to the first drive mode is satisfied. Specifically, in step S113, the drive mode control unit 63 determines whether or not the inverter temperature T is lower than a predetermined first drive mode transition trigger temperature Td1. The first drive mode transition trigger temperature Td1 is set lower than the first third drive mode transition trigger temperature Tu1 and the second drive mode transition trigger temperature Td2, and is 65 ° C., for example.

  When the inverter temperature T is equal to or higher than the first drive mode transition trigger temperature Td1, the drive mode control unit 63 ends the present drive mode switching control process as it is. On the other hand, when the inverter temperature T is lower than the first drive mode transition trigger temperature Td1, the drive mode control unit 63 shifts the drive mode from the third drive mode to the first drive mode in step S114. Then, the drive mode switching control process is terminated.

  Incidentally, in the present embodiment, the first third drive mode transition trigger temperature Tu1 and the first drive mode transition trigger temperature Td1 are the first drive mode within the guaranteed operating range of each power switching element Qu1 to Qw2. The temperature range for driving is set to be wider than the temperature range for driving in the third drive mode. The second third drive mode transition trigger temperature Tu2 and the second drive mode transition trigger temperature Td2 are within the guaranteed operating range of each power switching element Qu1 to Qw2, and the temperature range for driving in the second drive mode is It is set to be wider than the temperature region driven in the third drive mode.

Next, the effect | action of this embodiment is demonstrated using FIG.
As shown in FIG. 5, when the inverter temperature T is relatively low (T ≦ Tu1), the drive mode is set to the first drive mode or the second drive mode according to the success or failure of the two-phase modulation condition.

  Further, under the condition where the two-phase modulation condition is not satisfied, the drive mode is set to the first drive mode or the third drive mode according to the inverter temperature T. On the other hand, under the condition where the two-phase modulation condition is satisfied, the drive mode is the second drive mode or the third drive mode depending on the inverter temperature T and the control mode of the electric motor 13 (whether or not the field weakening control is being performed). Set to

According to the embodiment described above in detail, the following effects are obtained.
(1) The electric compressor 10 includes a compressor 12 that compresses a refrigerant as a fluid, an electric motor 13 that drives the compressor 12, an inverter 31 that serves as a drive circuit that drives the electric motor 13, and the temperature of the inverter 31. And a control unit 55 that controls the inverter 31. The control unit 55 includes a drive mode control unit 63 that controls the drive mode of the inverter 31.

  Here, the drive mode includes a first drive mode in which the carrier frequency f is the first carrier frequency f1 and the modulation method is a three-phase modulation method, and a second drive mode in which the modulation method is a two-phase modulation method. And a third drive mode in which the carrier frequency f is a third carrier frequency f3 lower than the first carrier frequency f1 and the modulation scheme is a three-phase modulation scheme. Then, the drive mode control unit 63 controls the drive mode based on the inverter temperature T, the rotation speed r of the electric motor 13 and the modulation factor M. Thereby, since the inverter 31 can be driven in the optimal drive mode according to a situation, it can suppress suitably that the inverter temperature T becomes high too much.

  More specifically, the drive mode includes a first drive mode and a second drive mode. In the first drive mode, the modulation method is a three-phase modulation method, and is excellent in versatility. On the other hand, the second drive mode is a drive mode in which the modulation method is a two-phase modulation method. Since the two-phase modulation method tends to reduce power loss as compared with the three-phase modulation method, the amount of heat generation tends to be small. However, in order to change the modulation method to the two-phase modulation method, there may be a certain condition (two-phase modulation condition) defined by the rotational speed r or the like. For this reason, the drive mode cannot be shifted to the second drive mode depending on, for example, the rotational speed r, and the drive mode is maintained in the first drive mode for a long period of time. As a result, the inverter temperature T is excessive. For example, the inverter temperature T may become higher than the operation upper limit temperature Tmax.

  On the other hand, according to the present embodiment, the drive mode is provided with the third drive mode separately from the first drive mode and the second drive mode. In the third drive mode, since the carrier frequency f is set lower than the first carrier frequency f1, the amount of heat generation is likely to be smaller than in the first drive mode. The third drive mode can be set regardless of conditions such as the rotation speed r because the modulation method is a three-phase modulation method. For this reason, for example, when the inverter temperature T becomes relatively high, the temperature increase of the inverter temperature T can be suppressed by shifting the drive mode from the first drive mode to the third drive mode.

  Here, focusing on the viewpoint of suppressing power loss, for example, it is conceivable to always set the drive mode to the third drive mode. However, since the carrier frequency f is set low in the third drive mode, noise is likely to increase. On the other hand, according to the present embodiment, both suppression of noise and suppression of excessive increase in inverter temperature T are achieved by switching the drive mode to one of the drive modes depending on the situation. Can be made. Therefore, the inverter 31 can be suitably driven within a range where the inverter temperature T does not become excessively high.

  (2) The drive mode control unit 63 determines the drive mode based on the fact that the two-phase modulation condition defined by both the rotation speed r and the modulation factor M is satisfied in the situation where the drive mode is the first drive mode. The first drive mode is shifted to the second drive mode. Then, the drive mode control unit 63 drives based on the fact that the inverter temperature T becomes higher than the predetermined first third drive mode transition trigger temperature Tu1 in the situation where the drive mode is the first drive mode. The mode is shifted from the first drive mode to the third drive mode. As a result, when the two-phase modulation condition is satisfied, the drive mode is shifted from the first drive mode to the second drive mode, thereby reducing power loss and heat generation. Further, when the inverter temperature T becomes higher than the first third drive mode transition trigger temperature Tu1, the drive mode shifts from the first drive mode to the third drive mode, so that the power loss and the heat generation amount are increased. Reduction can be achieved. Thereby, it can suppress that inverter temperature T becomes high too much, suppressing a noise.

  In particular, the first third drive mode transition trigger temperature Tu1 is set lower than the operation upper limit temperature Tmax of each of the power switching elements Qu1 to Qw2. As a result, the drive mode can be shifted to the third drive mode before the operation of each of the power switching elements Qu1 to Qw2 is hindered, and the inverter temperature T can be prevented from reaching the operation upper limit temperature Tmax.

  (3) In the situation where the drive mode is the first drive mode, the drive mode control unit 63 satisfies the two-phase modulation condition, and the inverter temperature T is greater than the first third drive mode transition trigger temperature Tu1. If it is higher, the drive mode is shifted from the first drive mode to the second drive mode. According to such a configuration, when both the transition condition to the second drive mode and the transition condition to the third drive mode are satisfied, the drive mode preferentially shifts to the second drive mode. In the second drive mode, the amount of heat generation is smaller than in the first drive mode, and noise is likely to be smaller than in the third drive mode. Thereby, coexistence with suppression of a noise and suppression of a raise of inverter temperature T can be aimed at by shifting to the 2nd drive mode preferentially.

  (4) The drive mode control unit 63 switches the drive mode from the second drive mode to the second drive mode based on the fact that a predetermined third drive mode transition condition is satisfied in a situation where the drive mode is the second drive mode. Transition to the three drive mode. The third drive mode transition condition includes that the inverter temperature T becomes higher than the second third drive mode transition trigger temperature Tu2, and the second third drive mode transition trigger temperature Tu2 is the first third The drive mode transition trigger temperature Tu1 is set higher.

  According to this configuration, the second third drive mode transition trigger temperature Tu2 used for the transition condition from the second drive mode to the third drive mode is used for the transition condition from the first drive mode to the third drive mode. It is higher than the first third drive mode transition trigger temperature Tu1. Thereby, in the 1st drive mode in which the emitted-heat amount tends to become large compared with 2nd drive mode, since it transfers to 3rd drive mode comparatively early, it can respond to the temperature rise of inverter temperature T at an early stage. On the other hand, in the second drive mode in which the amount of generated heat is likely to be smaller than that in the first drive mode, the second drive mode is maintained for a relatively long period of time, so noise can be suppressed.

  (5) The control unit 55 includes a field weakening control unit 64 that performs field weakening control on the electric motor 13 when a predetermined field weakening condition is satisfied. As a result, for example, the required electric power required for driving the electric motor 13 can be input to the electric motor 13 by performing field-weakening control even under a condition where the rotational speed r is relatively high and the power supply voltage is relatively low. it can.

  Here, in the field weakening control, the amount of generated heat tends to be smaller than in the normal control. For this reason, the amount of heat generated when the drive mode is the second drive mode and the field weakening control is performed may be substantially the same as or smaller than the amount of heat generated in the third drive mode. In this respect, in this embodiment, even if the drive mode is the second drive mode and the inverter temperature T is higher than the second third drive mode transition trigger temperature Tu2, the field-weakening control is performed. If it is, the transition from the second drive mode to the third drive mode is not performed. Thereby, it is possible to suppress unnecessary transition of the drive mode.

  (6) The drive mode control unit 63 sets the drive mode to the third drive based on the fact that the inverter temperature T becomes lower than the first drive mode transition trigger temperature Td1 in the situation where the drive mode is the third drive mode. The mode is shifted to the first drive mode. Further, in the situation where the drive mode is the third drive mode, the drive mode control unit 63 determines that the inverter temperature T is lower than the second drive mode transition trigger temperature Td2 and the two-phase modulation condition is satisfied. Based on this, the drive mode is shifted from the third drive mode to the second drive mode. As a result, the transition from the third drive mode to the second drive mode can be performed without going through the first drive mode, so that unnecessary transition of the drive mode can be avoided.

  The first drive mode transition trigger temperature Td1 is set lower than the second drive mode transition trigger temperature Td2. Thus, in the first drive mode with a relatively large amount of heat generation, the transition is made after the inverter temperature T has sufficiently decreased, so that the temperature increase of the inverter temperature T can be suppressed, while the second drive with a relatively small amount of heat generation. Since the mode shifts relatively early, noise can be suppressed.

  (7) The first drive mode transition trigger temperature Td1 is lower than the first third drive mode transition trigger temperature Tu1, and the second drive mode transition trigger temperature Td2 is greater than the second third drive mode transition trigger temperature Tu2. Is also low. Accordingly, for example, immediately after the transition from the third drive mode to the first drive mode is performed, the transition from the first drive mode to the third drive mode can be suppressed.

In addition, you may change the said embodiment as follows.
The control unit 55 may stop the electric motor 13 based on the fact that the inverter temperature T has reached a predetermined stop trigger temperature during the rotation of the electric motor 13. In this case, the stop trigger temperature may be a temperature that is the same as or lower than the operation upper limit temperature Tmax by a predetermined margin, for example.

  In such a configuration, each of the third drive mode transition trigger temperatures Tu1, Tu2 may be set lower than the stop trigger temperature. Thereby, since the drive mode shifts to the third drive mode before the electric motor 13 stops, a situation where the electric motor 13 stops can be avoided, or the period until the electric motor 13 stops is lengthened. be able to. Therefore, the inconvenience that the electric motor 13 stops, for example, the driver's discomfort caused by the stop of the operation of the vehicle air conditioner 100 can be suppressed.

The first carrier frequency f1 and the third carrier frequency f3 are arbitrary as long as the third carrier frequency f3 is lower than the first carrier frequency f1.
The second carrier frequency f2 is the same as the first carrier frequency f1, but is not limited thereto, and may be lower or higher than the first carrier frequency f1. In short, in the second carrier frequency f2, during normal control (non-weakening field control), the amount of heat generated in the second drive mode is smaller than the amount of heat generated in the first drive mode, and the noise is smaller than in the third drive mode. It suffices if it is set as appropriate. In other words, the second drive mode is a drive mode in which the modulation method is a two-phase modulation method, and the amount of heat generation is smaller than that of the first drive mode and noise is smaller than that of the third drive mode at least during normal control. If it is.

  Each drive mode transition trigger temperature Tu1, Tu2, Td1, Td2 is not limited to the temperature of the embodiment as long as it is equal to or lower than the operation upper limit temperature Tmax, and is arbitrary. For example, both the third drive mode transition trigger temperatures Tu1 and Tu2 may be set to be the same, or the first drive mode transition trigger temperature Td1 and the second drive mode transition trigger temperature Td2 may be set to the same. Furthermore, for example, the first third drive mode transition trigger temperature Tu1 and the first drive mode transition trigger temperature Td1 may be set to be the same.

  The two-phase modulation condition is defined by both the rotational speed r and the modulation factor M, but is not limited thereto, and may be a condition defined by either one. For example, in the configuration in which the upper arm power switching elements Qu1, Qv1, and Qw1 are turned on by another method instead of the bootstrap circuit 61, the condition of the rotational speed r may be omitted. Further, when the minimum duty ratio that can be realized by the inverter 31 is sufficiently small, the condition of the modulation factor M may be omitted. In short, the two-phase modulation condition may be a condition defined by at least one of the rotational speed r and the modulation factor M. In other words, the drive mode control unit 63 may control the drive mode based on at least one of the rotation speed r and the modulation factor M and the inverter temperature T.

  A direct transition from the third drive mode to the second drive mode may be omitted. Even in this case, the transition from the third drive mode to the second drive mode is performed via the first drive mode. However, the drive mode transition is performed as long as the useless drive mode transition is performed and the inverter temperature T is not lower than the first drive mode transition trigger temperature Td1 lower than the second drive mode transition trigger temperature Td2. If attention is paid to this point, it is better to be able to make a direct transition from the third drive mode to the second drive mode.

  ○ In the situation where the drive mode is the first drive mode, priority is given to the transition to the third drive mode when both the transition condition to the second drive mode and the transition condition to the third drive mode are satisfied. May be.

○ The field weakening control unit 64 may be omitted. That is, a configuration in which field-weakening control is not performed may be used.
The attachment position of the case 32 with respect to the housing 11 is arbitrary.

  ○ The two-phase modulation method is not limited to the method using both the upper arm and the lower arm, but only the lower arm, in other words, only the power switching elements Qu2, Qv2, Qw2 of the lower arm are to be stopped. It may be a method.

O The mounting object of the electric compressor 10 is not limited to the vehicle, but is arbitrary.
Although the electric compressor 10 was used for the vehicle air conditioner 100, it is not restricted to this, You may be used for another apparatus. For example, when the vehicle is a fuel cell vehicle (FCV) equipped with a fuel cell, the electric compressor 10 may be used in a supply device that supplies air to the fuel cell. In short, the fluid to be compressed is arbitrary and may be a refrigerant or air.

Next, a preferable example that can be grasped from the embodiment and another example will be described below .

(B) The electric motor according to any one of claims 1 to 4 , wherein the electric motor is a three-phase motor, and the drive circuit is a three-phase inverter.

  DESCRIPTION OF SYMBOLS 10 ... Electric compressor, 11 ... Housing, 12 ... Compression part, 13 ... Electric motor, 31 ... Inverter (drive circuit), 52 ... Power module, 55 ... Control part, 63 ... Drive mode control part, 64 ... Weak field control part , 100: Vehicle air conditioner, r: Speed of electric motor, M: Modulation rate, f: Carrier frequency, T: Inverter temperature (grasping temperature), Tu1: First third drive mode transition trigger temperature, Tu2: First 2 third drive mode transition trigger temperature, Td1... First drive mode transition trigger temperature, Td2... Second drive mode transition trigger temperature, Tmax.

Claims (4)

A compression section for compressing the fluid;
An electric motor for driving the compression unit;
A drive circuit for driving the electric motor and having a switching element;
A temperature grasping unit for grasping the temperature of the drive circuit;
A drive mode control unit that controls the drive mode of the drive circuit based on at least one of the rotational speed and modulation rate of the electric motor and the grasped temperature grasped by the temperature grasping unit ;
With
The drive mode is
A first drive mode in which the modulation method is a three-phase modulation method;
A second drive mode in which the modulation method is a two-phase modulation method;
A third drive mode having a carrier frequency lower than the carrier frequency of the first drive mode and a modulation scheme being a three-phase modulation scheme,
The drive mode control unit
In the situation where the drive mode is the first drive mode, the drive mode is changed to the first drive mode based on the fact that a two-phase modulation condition defined by at least one of the rotational speed and the modulation factor is satisfied. To shift to the second drive mode,
In the situation where the drive mode is the first drive mode, the drive mode is changed from the first drive mode to the first drive mode based on the grasped temperature becoming higher than a predetermined third drive mode transition trigger temperature. To shift to the third drive mode,
The drive mode control unit, when the drive mode is the first drive mode, the two-phase modulation condition is satisfied, and the grasped temperature is higher than the third drive mode transition trigger temperature In the electric compressor, the drive mode is shifted from the first drive mode to the second drive mode . A compression section for compressing the fluid;
An electric motor for driving the compression unit;
A drive circuit for driving the electric motor and having a switching element;
A temperature grasping unit for grasping the temperature of the drive circuit;
A drive mode control unit that controls the drive mode of the drive circuit based on at least one of the rotational speed and modulation rate of the electric motor and the grasped temperature grasped by the temperature grasping unit;
With
The drive mode is
A first drive mode in which the modulation method is a three-phase modulation method;
A second drive mode in which the modulation method is a two-phase modulation method;
A third drive mode having a carrier frequency lower than the carrier frequency of the first drive mode and a modulation scheme being a three-phase modulation scheme,
The drive mode control unit
In the situation where the drive mode is the first drive mode, the drive mode is changed to the first drive mode based on the fact that a two-phase modulation condition defined by at least one of the rotational speed and the modulation factor is satisfied. To shift to the second drive mode,
In the situation where the drive mode is the first drive mode, the drive mode is changed from the first drive mode to the first drive mode based on the grasped temperature becoming higher than a predetermined third drive mode transition trigger temperature. To shift to the third drive mode ,
The drive mode control unit, when the drive mode is the first drive mode, the two-phase modulation condition is satisfied, and the grasped temperature is higher than the third drive mode transition trigger temperature In the electric compressor, the drive mode is shifted from the first drive mode to the third drive mode . When a predetermined field weakening condition is established, a field weakening control unit that performs field weakening control on the electric motor is provided,
The third drive mode transition trigger temperature is a first third drive mode transition trigger temperature,
In the situation where the drive mode is the second drive mode, the drive mode control unit changes the drive mode from the second drive mode based on the establishment of a predetermined third drive mode transition condition. Shifting to the third drive mode,
The third drive mode transition condition, the grasping temperature Ri is higher than the second of the third drive mode transition trigger a predetermined temperature, and, by the field weakening control by the field weakening control unit is not performed Yes,
The electric compressor according to claim 1 or 2, wherein the second third drive mode transition trigger temperature is higher than the first third drive mode transition trigger temperature. The drive mode control unit
In the situation where the drive mode is the third drive mode, the drive mode is changed from the third drive mode to the third drive mode based on the grasped temperature being lower than a predetermined first drive mode transition trigger temperature. Shift to the first drive mode,
In the situation where the drive mode is the third drive mode, based on the grasp temperature is lower than a predetermined second drive mode transition trigger temperature, and the two-phase modulation condition is satisfied, Shifting the drive mode from the third drive mode to the second drive mode;
The first driving mode transition trigger temperature, rather lower than the second driving mode transition trigger temperature,
In the situation where the drive mode is the third drive mode, the drive mode control unit is a case where the grasped temperature is lower than the first drive mode transition trigger temperature, and the grasped temperature is further reduced to the second drive mode. The electric compressor according to claim 3 , wherein when the two-phase modulation condition is satisfied, the driving mode is shifted from the third driving mode to the second driving mode when the temperature is lower than a mode transition trigger temperature. .