JP2007318824A - Electric compressor drive device - Google Patents

Abstract

An object of the present invention is to provide a three-phase AC electric compressor driving device that can achieve temperature protection with a small number of components and a small number of wirings, and can achieve a reduction in size and weight.
A thermostat 8 that opens at a predetermined temperature is connected in series to a predetermined phase of a three-phase motor, and a control circuit 7 is connected to an inverter when a phase current detected by a current sensor 5 is zero. The phase current output of the circuit 10 is stopped, and the DC voltage of the DC power source 1 is applied to the thermostat 8. After that, when a predetermined current value is detected by the current sensor 5, the DC voltage is applied. The phase current output is resumed after a predetermined time has elapsed since the detection of the predetermined current value.
[Selection] Figure 2

Description

  The present invention relates to temperature protection for an electric compressor.

  2. Description of the Related Art Conventionally, an electric compressor provided with a temperature sensor (such as a thermistor or a thermostat) is known for protecting the temperature of the electric compressor (see, for example, Patent Document 1).

  An example of this electric compressor will be described below. FIG. 10 shows an electric compressor 106 provided with a sensorless DC brushless motor (hereinafter referred to as a motor). In the figure, a compression mechanism section 28 (a scroll mechanism in this example), a motor 110 and the like are installed in a metal casing 32. The refrigerant is sucked from the suction port 33 and compressed by the compression mechanism unit 28 being driven by the motor 110. The compressed refrigerant passes through the motor 110 inside the metal housing 32, cools the motor 110 at that time, and is discharged from the discharge port 34. A temperature sensor 108 for detecting the temperature of the winding 4 is provided in the vicinity of the winding 4 of the motor 110.

  A terminal 39 connected to the winding 4 of the motor 110 inside the metal housing 32 and a temperature sensor terminal 37 connected to the temperature sensor 108 are connected to an inverter device (described later) outside the metal housing 32. It is connected to the. A side view of the terminal 39 and the temperature sensor terminal 37 is shown in FIG. 11, and a front view thereof is shown in FIG. Here, there is no difference in the shape of the two terminals. FIG. 13 is a perspective view of the faston terminal.

  In the drawing, an electrically insulating pin terminal holding portion 43 is attached to a base 44, and the pin terminal holding portion 43 fixes and holds a metal pin terminal 41 for electrical connection. A tab 42 and a tab 45 are attached to the pin terminal 41 by welding. A faston terminal 47 to which a connection line 46 is fixed by caulking is connected to the tab 42 and the tab 45. Therefore, the tab 45 of the terminal 39 is connected to the winding 4 of the motor 110 via the faston terminal 47 inside the metal housing 32, and the tab 45 of the terminal 37 is connected to the temperature sensor 108. The tab 42 is connected to the inverter device via the faston terminal 47 outside the metal housing 32.

  On the other hand, as an inverter device, there is known an inverter device that stops the output of a three-phase alternating current by a signal from the temperature sensor to protect the temperature of the motor (for example, see Patent Document 2).

  An example of this circuit will be described below. FIG. 14 shows an inverter device and its surrounding electric circuit. For the switching element 2, the upper arm switching element is defined as U, V, W, and the lower arm switching element is defined as X, Y, Z.

  The control circuit 107 of the inverter device 120 controls the switching element 2 that constitutes the inverter circuit 10 based on a rotation speed command signal (not shown) and the like, and switches the DC voltage from the battery 1 by PWM modulation. An alternating current is output to the stator winding 4 that is a component of the motor 110. The diode 3 constituting the inverter circuit 10 serves as a return route for the current flowing through the stator winding 4. Power is output from the rotor 5. The direct current value detected by the current sensor 6 is transmitted to the control circuit 107. And it is used for protection of the motor 110 and the switching element 2, calculation of power consumption, etc.

The temperature of the motor winding 4 from the temperature sensor 108 (thermistor in this case) is transmitted to the control circuit 107. When the temperature reaches a predetermined temperature (around 100 ° C.), the control circuit 1
07 stops driving the switching element 2 and protects the motor 110 from overheating.

  Unlike the above, a single-phase AC electric compressor drive device that performs temperature protection without using an inverter device is also known (see, for example, Patent Document 3).

An example of this circuit will be described below. FIG. 15 is an electric circuit diagram of a conventional single-phase AC electric compressor driving apparatus. In the figure, a single-phase AC voltage is applied from the commercial power source 201 to the auxiliary winding 203 via the main winding 204 and the operating capacitor 206, and the single-phase AC motor is driven. Here, since the protector 205 is connected in series, the current protection of the single-phase AC voltage can be directly cut off during overload operation, and temperature protection can be performed. Since there is no overcurrent protection function compared to the case where an inverter device is used, the protector 205 can cut off the energization not only when the temperature exceeds the reference but also when the current exceeds the reference.
JP 2002-276550 A (page 10, FIG. 8 to FIG. 10, page 9, FIG. 3 to FIG. 4) Japanese Patent Application Laid-Open No. 08-040053 (5th page, FIGS. 1 and 3) JP 2004-301039 A (7th page, FIG. 5)

  When the inverter device outputs a three-phase alternating current and drives the motor of the electric compressor at a variable speed, a temperature sensor terminal is required to perform temperature protection as described above. Instead of two 3-terminal terminals, one 5-terminal terminal may be used, but the number of parts increases and the terminal becomes larger.

  On the other hand, when the energization is directly cut off as in the single-phase AC electric compressor driving device, the temperature sensor terminal is not required. However, in the case of three-phase alternating current, it is necessary to provide at least two phases because the current cannot be completely cut off only by providing the protector in one phase (since the inverter device has an overcurrent protection function, It may be a thermostat that can cut off electricity only at a temperature above the standard). Therefore, in the case of three-phase alternating current, even when a temperature sensor terminal is provided or when a plurality of thermostats are provided in two or more phases, there is a problem for reduction in size and weight.

  SUMMARY OF THE INVENTION The present invention solves such conventional problems, and an object of the present invention is to provide a three-phase AC electric compressor drive device that can achieve temperature protection with a small number of parts and a small number of wires, and that can achieve a reduction in size and weight.

  In order to solve the above problems, an electric compressor driving device according to the present invention includes an inverter circuit including three phases of an upper arm switching element connected to the plus side of a DC power source and a lower arm switching element connected to the minus side. The inverter circuit includes a control circuit that outputs a phase current to each phase of the stator winding of the three-phase motor that is a drive source of the electric compressor, and a current sensor that detects the phase current, and the control circuit includes at least the current sensor The inverter circuit is controlled based on the detected phase current. A thermostat that opens at a predetermined temperature is connected in series to a predetermined phase that is a specific phase of the three-phase motor, and the control circuit is an inverter circuit when the phase current of the predetermined phase detected by the current sensor is zero. All three phases are stopped, and the DC voltage of the DC power supply is applied to the thermostat. After that, when the predetermined current value is detected by the current sensor, the application of the DC voltage is stopped The phase current output is resumed after a lapse of a predetermined time from the value detection.

  With the above configuration, when a three-phase alternating current is output to drive the motor of the electric compressor, a temperature sensor terminal is not required, and temperature protection is possible with only one thermostat. The current sensor is used for phase current detection used for controlling the inverter circuit, and has been provided for some time. Therefore, temperature protection is possible with fewer parts and fewer wires, and the three-phase AC electric compressor drive device can be reduced in size and weight.

  The three-phase AC electric compressor driving device of the present invention can be temperature-protected with a small number of components and a small number of wires, and can achieve a reduction in size and weight.

  The first invention is an inverter circuit having three phases of an upper arm switching element connected to the plus side of a DC power source and a lower arm switching element connected to the minus side, and the inverter circuit is a drive source for an electric compressor. A control circuit that outputs a phase current to each phase of the stator winding of the three-phase motor and a current sensor that detects the phase current, and the control circuit controls the inverter circuit based on at least the phase current detected by the current sensor To do. A thermostat that opens at a predetermined temperature is connected in series to a predetermined phase that is a specific phase of the three-phase motor, and the control circuit is an inverter circuit when the phase current of the predetermined phase detected by the current sensor is zero. All three phases are stopped, and the DC voltage of the DC power supply is applied to the thermostat. After that, when the predetermined current value is detected by the current sensor, the application of the DC voltage is stopped The phase current output is resumed after a lapse of a predetermined time from the value detection.

  With the above configuration, when a three-phase alternating current is output and the motor of the electric compressor is driven, a temperature sensor terminal is not required, and the temperature can be protected with only one thermostat. The current sensor is used for phase current detection used for controlling the inverter circuit, and has been provided for some time. Therefore, temperature protection is possible with fewer parts and fewer wires, and the three-phase AC electric compressor drive device can be reduced in size and weight.

  According to a second aspect of the present invention, in the electric compressor driving device of the first aspect, the detection of the phase current zero of the predetermined phase by the current sensor is detected at a peripheral phase where the phase current value of the predetermined phase peaks. . Thereby, since it detects in the phase away from the zero cross phase from which output current itself becomes zero, it can avoid misjudging that the electric current is zero by the contact of a thermostat being opened.

  According to a third aspect of the present invention, in the electric compressor driving device of the first aspect, the detection of the phase current zero of the predetermined phase by the current sensor is continuously performed at a plurality of points in the phase current phase of the predetermined phase. As a result, even if zero current is detected at one point in the zero cross phase where the output current itself becomes zero, detection at other points does not become zero. Therefore, continuous detection of zero current by opening the thermostat contact is possible. Can be distinguished.

  According to a fourth aspect of the invention, in the electric compressor driving device according to the first aspect of the invention, the detection of the phase current zero of the predetermined phase by the current sensor is obtained from the sum of the phase current values of the two phases other than the predetermined phase. Thereby, the detection accuracy of the current sensor at a small current value becomes unnecessary. Therefore, it is easy to determine whether the phase current value of the predetermined phase is zero.

  According to a fifth aspect of the present invention, in the electric compressor driving device according to the first to fourth aspects of the present invention, when a DC voltage of a DC power source is applied to the thermostat, an upper arm switching element of a predetermined phase and another one-phase lower arm switching element Is turned on or the lower arm switching element of a predetermined phase and the upper arm switching element of the other one phase are turned on. As a result, the total inductance value of the windings increases, so that the linear increase in current becomes gradual and current detection becomes easy.

  According to a sixth aspect of the invention, in the electric compressor driving device according to the first to fifth aspects of the invention, an overcurrent protection operation is used instead of the detection of the predetermined current value by the current sensor. Overcurrent protection has been provided. That is, a function for determining whether or not the direct current value has reached a predetermined current value is already provided. Therefore, this can simplify the software of the control circuit. Output OFF can be substituted.

  According to a seventh aspect, in the electric compressor driving device according to the first to sixth aspects, the inverter device is mounted on the electric compressor. In an electric compressor integrated with an inverter device, the electric compressor and the inverter device are integrated, and thus it is required to be small. Therefore, it is not necessary to make a space for a plurality of thermostats and temperature sensor terminals, and the present invention in which a temperature sensor circuit is unnecessary is preferable.

  An eighth invention is an inverter device according to the first to seventh inventions, which is mounted on a vehicle. For vehicles, there is a restriction on the mounting space, a reduction in size is required, and there is a restriction on weight in terms of running performance. Therefore, this electric compressor drive device that can be reduced in size and weight is useful.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of an electric compressor in the electric compressor driving device according to the first embodiment of the present invention, and FIG. 2 is an inverter device of the electric compressor driving device and an electric circuit diagram of the periphery thereof. In the electric compressor 25 of FIG. 1, a compression mechanism 28, the motor 11, and the thermostat 8 are installed inside a metal housing 32. The refrigerant is sucked from the suction port 33 and is compressed by driving the compression mechanism 28 by the motor 11. The compressed refrigerant passes through the motor 11 inside the metal housing 32, cools the motor 11 at that time, and is discharged from the discharge port 34. The thermostat 8 is provided in the vicinity of the winding 4 of the motor 11 so that the accurate temperature of the winding 4 can be detected.

  The winding 4 of the motor 11 is connected to a terminal 39 inside the metal casing 32. Here, the thermostat 8 is connected in series to one of the three connections between the winding 4 of the motor 11 and the terminal 39. Therefore, the conventional temperature sensor terminal 37 in FIG. 10 is not required.

  Outside the metal housing 32, the terminal 39 is connected to the inverter device 20 of FIG. In connection with the terminal 39, a Faston terminal is used as in the conventional technique. The terminal 39 and the faston terminal 47 are the same as those in FIGS.

  In FIG. 2, for the switching element 2, the upper arm switching element is defined as U, V, W, and the lower arm switching element is defined as X, Y, Z. The diodes corresponding to the switching elements U, V, W, X, Y, and Z are defined as 3U, 3V, 3W, 3X, 3Y, and 3Z. The thermostat 8 is connected in series with the U-phase winding of the motor 11.

  The control circuit 7 is connected to the upper arm switching elements U, V, W and the lower arm switching elements X, Y, Z by a connection line 18 via a drive circuit (not shown) and the like. Is controlling. When the switching element 2 is an IGBT or a power MOSFET, the gate voltage is controlled. When the switching element 2 is a power transistor, the base current is controlled.

  The direct current value detected by the current sensor 6 is transmitted to the control circuit 7. And it is used for protection of motor 11 thru / or switching element 2, ie, overcurrent protection, position detection of magnet rotor 5, and calculation of power consumption. The current sensor 6 may be any sensor that can detect an instantaneous peak current, such as a current sensor using a Hall element or a shunt resistor. Alternatively, each switching element 2 may be individually provided in series. It may be provided on the positive side of the power supply line.

  The control circuit 7 of the inverter device 20 controls the switching element 2 constituting the inverter circuit 10 based on the direct current value detected by the current sensor 6, the rotation speed command signal (not shown), etc. By switching the DC voltage by PWM modulation, a sinusoidal AC current is output to the stator winding 4 that is a component of the motor 11. Then, power is output from the rotor 5. The diode 3 provides a return route for the current flowing through the stator winding 4.

  The operation of temperature protection with the above configuration will be described below. The phase current value of each phase appears in the DC current value detected by the current sensor 6. Therefore, the control circuit 7 constantly monitors the U-phase phase current value, which is a predetermined phase, to which the thermostat 8 is connected in series, among the DC current values detected by the current sensor 6. That is, when only U of the upper arm switching elements in which the phase current value of the U phase appears in the DC current value is ON or only X of the lower arm switching elements is ON, the DC current value (= phase current value of the U phase) Confirm.

  When the winding temperature of the motor 11 rises and reaches a predetermined temperature (around 100 ° C.) to be protected from overheating, the thermostat 8 provided in the vicinity of the winding 4 of the motor 11 is opened as shown in FIG. . Thereby, the phase current value of the U phase is cut off, and the phase current value of the U phase detected by the current sensor 6 becomes zero. On the other hand, the phase current of the V phase and the phase current of the W phase continue to flow, which may cause trouble in overheat protection. In addition, vibration noise is generated due to the unbalanced current. Therefore, the control circuit 7 turns off all the switching elements U, V, W, X, Y, and Z of the three phases. Thereby, the phase current output to the motor 11 of the inverter circuit 10 is in a stopped state for all three phases.

  Next, the control circuit 7 turns on the upper arm switching element U and the lower arm switching element Y. The electric circuit in this state is shown in FIG. The ON switching element is indicated by a short circuit, and the OFF switching element is open and not displayed. As a result, the DC voltage of the battery 1 is applied to the thermostat 8 via the U-phase motor winding, the V-phase motor winding, and the current sensor 6. Then, the control circuit 7 monitors whether the current sensor 6 detects a direct current value.

  When the stop state of the motor 11 elapses and the winding temperature of the motor 11 decreases and reaches an operable temperature, the contact of the thermostat 8 is closed as shown in FIG. At this time, the current indicated by the arrow I flows from the battery 1 to the thermostat 8, the U-phase motor winding, the V-phase motor winding, and the current sensor 6. Since the battery 1 is a DC voltage and the load motor winding is an inductance, this current increases linearly over time as shown in FIG. If the DC voltage of the battery 1 is E, the inductance value for one phase of the motor winding is L, the current is i, and the time is t, then di / dt = E / 2L.

  At the same time when the DC current value reaches a predetermined current value Ip (at time Tp), the control circuit 7 turns off the upper arm switching element U and the lower arm switching element Y. As a result, the current flowing in the motor winding 4 flows to the battery 1 side via the diode 3X and the diode 3V. The direct current value becomes negative and becomes zero at time 2Tp. The control circuit 7 restarts the motor 11 after this point in order to make the current at the start three-phase balanced. That is, the motor 11 may be restarted after a predetermined time Tp after the direct current value reaches a predetermined current value Ip.

  As a specific numerical example, if E = 200V and L = 1mH, then di / dt = 200 / 2m = 100k. When Ip is set to 10A, Tp = 10 / 100k = 0.1 m. Therefore, after the direct current value reaches 10 A, the motor 11 is restarted after 0.1 mS. That is, the predetermined current value is 10 A, and the predetermined time is 0.1 mS.

  FIG. 7 is a flowchart showing the temperature protection operation. In step 10, it is determined whether the phase current value of the U phase is zero. If it is not zero (N), the determination is repeated. If zero (Y), go to step 20. Here, all the switching elements U, V, W, X, Y, and Z of the three phases are turned OFF. Next, in step 30, the upper arm switching element U and the lower arm switching element Y are turned ON. Then, in step 40, it is determined whether or not the direct current value has reached a predetermined current value Ip. If the predetermined current value Ip has not been reached (N), the determination is repeated. If the predetermined current value Ip has been reached (Y), the process proceeds to step 50. In step 50, the upper arm switching element U and the lower arm switching element Y are turned OFF. In step 60, after reaching the predetermined current value Ip, the motor 11 is restarted after the predetermined time Tp.

  As described above, when a three-phase alternating current is output to drive the motor of the electric compressor, the temperature sensor terminal is not required, and the temperature can be protected with only one thermostat. The current sensor is used for phase current detection used for controlling the inverter circuit, and has been provided for some time. Therefore, temperature protection is possible with fewer parts and fewer wires, and the three-phase AC electric compressor drive device can be reduced in size and weight.

  In step 30, the upper arm switching element U and the lower arm switching element Y are turned on. However, the same applies even if the lower arm switching element X and the upper arm switching element V are turned on. In step 30 and step 40, the U-phase motor winding and the V-phase motor winding are connected in series, and the W-phase motor winding is opened. The purpose of this is to increase the total inductance value of the windings, moderate the linear increase in current, and facilitate current detection. Therefore, the W-phase motor winding may be connected in parallel with the U-phase motor winding or the V-phase motor winding. In this case, the time Tp is shortened. Since the detection of the predetermined current value Ip is a determination that the thermostat contact is closed, it may be a current value greater than zero.

(Embodiment 2)
FIG. 8 is a phase characteristic diagram of each phase current waveform according to the second embodiment of the present invention, which is a sinusoidal alternating current output from the inverter device 20. A phase current 51 of the U phase, a phase current 52 of the V phase, and a phase current 53 of the W phase are shown in relation to the phase. The current change due to the phase makes a round with a phase width of 360 degrees. Moreover, these phase currents appear in the direct current.

  In the second embodiment, step 10 for determining whether or not the phase current value of the U phase is zero in the first embodiment is performed in a peripheral phase where the phase current value of the U phase becomes the peak value in FIG. is there. In other words, the phase is around 90 degrees and 270 degrees. As a result, detection is performed at a phase away from the zero-crossing phase where the output current itself becomes zero, 180 degrees, and 360 degrees, so that it is possible to avoid erroneously determining that the current is zero due to the opening of the thermostat contact. .

In the second embodiment, step 10 for determining whether the phase current value of the U phase is zero in the first embodiment is continuously performed at a plurality of points in the phase instead of one point in the phase in FIG. Is. As a result, even if zero current at one point of zero crossing phase where the output current itself becomes zero, 180 degrees, 360 degrees is detected, detection at other points does not become zero, so the thermostat contact is opened. It can be distinguished from the continuous detection of zero current.

  Further, in the second embodiment, in the step 10 for determining whether or not the phase current value of the U phase is zero in the first embodiment, the phase current value of the U phase is changed to the phase current value of the V phase and the phase current of the W phase. It is obtained from the sum of values. That is, in order to detect the small DC current value zero by the current sensor 6, the current value must be accurately detected over a wide range from zero to the maximum. As for the three-phase current, Kirchoff's law of law is applied at the neutral point of the stator winding 4, so when the phase current value of the U phase is small, the phase current value of the V phase and the phase current value of the W phase. Is big. Therefore, by obtaining the phase current value of the U phase from the sum of the phase current value of the V phase and the phase current value of the W phase, the detection accuracy of the current sensor 6 at a small current value becomes unnecessary. Therefore, it is easy to determine whether or not the phase current value of the U phase is zero.

(Embodiment 3)
In the third embodiment, an overcurrent protection operation is used instead of determining whether or not the direct current has reached the predetermined current value Ip in step 40 of the first embodiment. The direct current value detected by the current sensor 6 is transmitted to the control circuit 7 and used for protection of the motor 11 to the switching element 2, that is, overcurrent protection. That is, a function for determining whether or not the direct current value has reached a predetermined value is already provided. Therefore, the software of the control circuit 7 can be simplified thereby. The output OFF in step 50 can be substituted.

  As a specific numerical example, if the current value of overcurrent protection is 20 A and the other numerical values are the same as those in the first embodiment, Tp = 20 / 100k = 0.2 mS when Ip = 20 A. Therefore, after the DC current value reaches 20 A, the motor 11 is restarted after 0.2 mS has elapsed.

(Embodiment 4)
FIG. 9 is a cross-sectional view of the inverter apparatus-integrated electric compressor according to Embodiment 4 of the present invention, and shows a configuration in which the inverter apparatus 20 is attached in close contact with the right side of the electric compressor 40. The compression mechanism 28, the motor 11, and the like are installed in the metal casing 32. The refrigerant is sucked from the suction port 33 and is compressed by driving the compression mechanism portion 28 (scroll in this example) by the motor 11. The compressed refrigerant cools the motor 11 when passing through the motor 11 and is discharged from the discharge port 34. A thermostat 8 is provided in the vicinity of the winding 4 of the motor 11 for cutting off energization when the temperature of the winding 4 reaches a predetermined temperature. The inverter device 20 uses a case 30 so as to be attached to the electric compressor 40. The inverter circuit unit 10 serving as a heat source is cooled by the low-pressure refrigerant through the low-pressure pipe 38.

  The connection line 36 fixed to the inverter device 20 by the holding unit 35 includes a power line to the battery 1 and a signal line to an air conditioner controller (not shown) that transmits a rotation speed signal. A terminal 39 connected to the winding 4 of the motor 11 inside the electric compressor 40 is connected to the output section of the inverter circuit section 10. Here, the thermostat 8 is connected in series only to one phase of the three winding phases of the motor 11. Therefore, a large space is not necessary, and a terminal for the temperature sensor is not necessary, so that parts can be reduced and the size can be reduced. Wiring can also be reduced.

  In such an inverter device integrated electric compressor, since the electric compressor and the inverter device are integrated, it is required to be small. Therefore, it is not necessary to make a space for a plurality of thermostats and temperature sensor terminals, and the present invention in which a temperature sensor circuit is unnecessary is preferable.

In each embodiment, the thermostat is provided in the U phase, but may be in the V phase or the W phase. Although the thermostat is provided in the container of the electric compressor, it may be provided outside the container. PWM
Although the case where a sine wave AC current is output to the motor by modulation has been shown, the present invention can also be applied to a rectangular wave AC current or the like. It can also be applied to PAM modulation. Although the thermostat has shown the case where the temperature of a coil | winding is detected, it is applicable not only to this but the temperature detection of a compression mechanism part. Although the DC power supply is a battery, the present invention is not limited to this, and a DC power supply obtained by rectifying a commercial AC power supply may be used. Although the motor is a sensorless DC brushless motor, it can also be applied to a reluctance motor, an induction motor, or the like. Although the case of three phases has been described as an example, the present invention can also be applied to multiphase.

  Furthermore, in vehicles, particularly electric vehicles and hybrid cars, the vehicle air conditioner is required to be compact and lightweight from the viewpoint of ensuring running performance and mounting properties, and among them, it is heavy and has a heavy weight in a narrow engine room and other spaces. It is important to reduce the size and weight of the electric compressor attached to the motor. The electric compressor driving device of the present invention can be downsized by the configuration shown in each embodiment, and the compressor itself can be downsized if it is integrated with the compressor. It is very suitable as a device or a general air conditioner.

  As described above, the three-phase AC electric compressor driving device according to the present invention can be applied to various consumer products and various industrial devices because the number of components can be reduced and the size can be reduced. Moreover, it is applicable not only to the motor of an electric compressor but also to a general temperature protection device for a motor. The load can be applied to AC devices other than motors.

Sectional drawing of the electric compressor in the electric compressor drive device which concerns on Embodiment 1 of this invention Inverter device of the same electric compressor drive device and its surrounding electric circuit diagram Electrical circuit diagram when the thermostat of FIG. 2 is activated FIG. 3 is an electric circuit diagram showing a state where a DC voltage is output from the inverter device. FIG. 4 is an electric circuit diagram showing a state in which a direct current flows when the thermostat is restored. FIG. 5 is a characteristic diagram showing the time variation of DC current. The flowchart which shows the temperature protection series of operation | movement of the electric compressor drive device which concerns on Embodiment 1 of this invention. Phase characteristic diagram of each phase current waveform of electric compressor driving device according to embodiment 2 of the present invention Sectional drawing of the inverter apparatus integrated electric compressor of the electric compressor drive device which concerns on Embodiment 4 of this invention. Cross section of a conventional electric compressor Side view of a conventional terminal Front view of conventional terminal A perspective view of a conventional Faston terminal Conventional electric compressor drive device inverter device and peripheral electric circuit diagram Electric circuit diagram of a conventional single-phase AC electric compressor drive device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Switching element 3 Diode 4 Stator winding 5 Magnet rotor 6 Current sensor 7 Control circuit 8 Thermostat 10 Inverter circuit 11 Motor 20 Inverter device 25 Electric compressor 39 Terminal (for motor power supply)
40 Electric compressor (for inverter unit)

Claims (8)

An inverter circuit having three phases of an upper arm switching element connected to the plus side of the DC power source and a lower arm switching element connected to the minus side, and fixing of a three-phase motor as a drive source of the electric compressor to the inverter circuit A control circuit for outputting a phase current to each phase of the child winding; and a current sensor for detecting the phase current, wherein the control circuit controls the inverter circuit based on at least the phase current detected by the current sensor. In the electric compressor driving device, a thermostat that opens at a predetermined temperature is connected in series to a predetermined phase that is a specific one phase of the three-phase motor, and the control circuit detects the predetermined phase detected by the current sensor. When the phase current of the DC power source is zero, all three phases of the phase current output of the inverter circuit are stopped, and the DC power of the DC power source is connected to the thermostat. When a predetermined current value is detected by the current sensor after that, the application of the DC voltage is stopped and the phase current output is resumed after a predetermined time has elapsed since the detection of the predetermined current value. An electric compressor driving device. The electric compressor driving device according to claim 1, wherein the detection of the phase current zero of the predetermined phase by the current sensor is detected in a peripheral phase where the phase current value of the predetermined phase peaks. The electric compressor driving device according to claim 1, wherein detection of the phase current zero of the predetermined phase by the current sensor is continuously performed at a plurality of points in the phase current phase of the predetermined phase. The electric compressor driving device according to claim 1, wherein detection of the phase current zero of the predetermined phase by the current sensor is obtained from a sum of phase current values of two phases other than the predetermined phase. When applying the DC voltage of the DC power source to the thermostat, the upper arm switching element of the predetermined phase and the other one-phase lower arm switching element are turned ON or the lower arm switching element of the predetermined phase and the other one-phase upper arm switching The electric compressor driving device according to any one of claims 1 to 4, wherein the element is turned on. The electric compressor drive device according to any one of claims 1 to 5, wherein an overcurrent protection operation is used instead of detection of a predetermined current value by the current sensor. The electric compressor drive device according to any one of claims 1 to 6, wherein the inverter device is mounted on the electric compressor. The electric compressor drive device according to any one of claims 1 to 7, which is mounted on a vehicle.