JP4539237B2 - Inverter device - Google Patents

Description

  The present invention relates to a phase current detection method for an inverter device that performs PWM modulation.

  Conventionally, as this type of phase current detection method, a method of directly detecting the current of the output line from the inverter device is known (for example, see Patent Document 1).

  This circuit will be described below (hereinafter referred to as a direct detection method).

  FIG. 10 shows an inverter device and its peripheral electric circuit. The control circuit 7 of the inverter device 20 inputs a U-phase current from the current sensor 8 and a V-phase current from the current sensor 9, and calculates a W-phase current from the two current values (stator winding). Kirchhoff's current law applies at the neutral point of 4). Based on these current values, the induced voltage of the stator winding 4 by the magnet rotor 5 constituting the sensorless DC brushless motor (hereinafter referred to as a motor) 11 is calculated, and the position of the magnet rotor 5 is detected. And based on a rotational speed command signal (not shown) etc., the switching element 2 (IGBT etc. is used) which comprises the inverter circuit 10 is controlled, and the DC voltage from the battery 1 is switched by PWM modulation, A sinusoidal alternating current is output to the stator winding 4 of the motor 11.

The diode 3 constituting the inverter circuit 10 serves as a return route for the current flowing through the stator winding 4. For the switching element 2, upper arm switching elements are defined as U, V, W, and lower arm switching elements are defined as X, Y, Z, and diodes corresponding to the switching elements U, V, W, X, Y, Z Is defined as 3U, 3V, 3W, 3X, 3Y, 3Z. It is difficult to configure the current sensor 8 and the current sensor 9 with a shunt resistor because the potential changes between the positive side and the negative side of the battery 1. And is configured using a Hall element.

  Therefore, a method of detecting a phase current using a shunt resistor advantageous for durability reliability and miniaturization is shown for a current sensor using a Hall element (see, for example, Patent Document 2).

  This method will be described below (hereinafter referred to as shunt method 1).

  FIG. 11 shows an inverter device and its peripheral circuits. The control circuit 12 of the inverter device 21 calculates the current based on the voltage from the power supply shunt resistor 6.

  FIG. 12 is a waveform characteristic diagram in three-phase 50% modulation, showing a U-phase terminal voltage 41, a V-phase terminal voltage 42, a W-phase terminal voltage 43 and a neutral point voltage 29. These terminal voltages are realized by duty (%) indicated on the vertical axis by PWM modulation. The neutral point voltage 29 is a value obtained by calculating the sum of the terminal voltages of each phase and dividing by 3. The phase voltage is a value obtained by subtracting the neutral point voltage from the terminal voltage, and is a sine wave.

  Similarly, FIG. 13 shows a waveform characteristic diagram in three-phase 100% modulation.

FIG. 14 is a timing chart within one carrier (carrier cycle) of three-phase modulation, and upper arm switching elements U, V, W and lower arm switching elements X, Y, Z within one carrier (carrier period). An example of ON / OFF is shown. However, in order to simplify the display, a dead time for preventing a short circuit between the upper arm switching element and the lower arm switching element is omitted. In this case, in the 50% modulation of FIG. 12, the phase is approximately 120 degrees. This is generally realized by a triangular wave and a timer function of a microcomputer.

  There are four types of switching of each switching element (a), (b), (c), and (d), which are shown in FIGS.

  In the period (a), all the upper arm switching elements U, V, W are OFF, and all the lower arm switching elements X, Y, Z are ON. U-phase current and V-phase current flow from the diodes 3X and 3Y in parallel with the lower arm switching elements X and Y to the stator winding 4, respectively, and W-phase current flows from the stator winding 4 to the lower arm switching element Z. ing. A current circulates between the lower arm and the motor 11 (hereinafter referred to as a lower circulation period). Therefore, power is not supplied from the battery 1 to the inverter circuit 10 (motor 11).

  In the period (b), the upper arm switching element U is ON, and the lower arm switching elements Y and Z are ON. U-phase current flows from upper arm switching element U to stator winding 4, V-phase current flows from diode 3Y in parallel with lower arm switching element Y to stator winding 4, and W-phase current flows to stator winding. 4 flows out to the lower arm switching element Z. For this reason, it is in the energized state in which electric power is supplied from the battery 1 to the inverter circuit 10 (motor 11). At this time, a U-phase current flows through the power supply line (power supply shunt resistor 6).

  In the period (c), the upper arm switching elements U and V are ON, and the lower arm switching element Z is ON. The U-phase current and the V-phase current flow from the upper arm switching elements U and V to the stator winding 4, respectively, and the W-phase current flows from the stator winding 4 to the lower arm switching element Z. For this reason, it is in the energized state in which electric power is supplied from the battery 1 to the inverter circuit 10 (motor 11). A W-phase current flows through the power line (power shunt resistor 6).

  In the period (d), all the upper arm switching elements U, V, W are ON, and all the lower arm switching elements X, Y, Z are OFF. The U-phase current and the V-phase current flow from the upper arm switching elements U and V to the stator winding 4 respectively, and the W-phase current flows from the stator winding 4 to the diode 3W in parallel with the upper arm switching element W. Yes. A current circulates between the upper arm and the motor 11 (hereinafter referred to as an upper circulation period). Therefore, power is not supplied from the battery 1 to the inverter circuit 10 (motor 11).

  As described above, it is possible to know the presence / absence of a current flowing through the power supply line (power supply shunt resistor 6) and the flowing phase current when the upper arm switching elements U, V, W are turned on / off. It does not flow when the upper arm switching element does not have an ON phase (de-energized, lower circulation). When only one phase is ON, the current of that phase flows (energized). When the two-phase is ON, the current of the remaining phase flows. (Energized) Does not flow when all three phases are ON (non-energized, upper circulation).

  FIG. 19 shows ON periods (Duty) of upper arm switching elements U, V, and W within one carrier (carrier cycle) in the phase of 30 to 90 degrees in 50% three-phase modulation of FIG. Based on the display.

  The ON period of the U-phase upper arm switching element U is represented by a thin solid line, the ON period of the V-phase upper arm switching element V is represented by a solid solid line, and the ON period of the W-phase upper arm switching element W is represented by a thick solid line. ing. The energization period during which power is supplied from the battery 1 to the stator winding 4 is indicated by solid arrows, and the phase currents flowing through the power supply line (power shunt resistor 6) at this time are indicated by U, V, and W. In addition, the circulation period (lower circulation period, upper circulation period) is indicated by a thick broken line arrow.

  Similarly, with respect to 100% three-phase modulation in FIG. 13, the phase of 30 to 90 degrees is shown in FIG. 20, the phase of 150 to 210 degrees is shown in FIG. 21, and the phase of 270 to 330 degrees is shown in FIG.

  Regarding the two-phase modulation, FIG. 23 shows a waveform characteristic chart in 100% modulation. FIG. 24 shows ON periods of the upper arm switching elements U, V, W in one carrier at a phase of 90 to 150 degrees, as in FIG. In the two-phase modulation, there is no period (d) in FIG.

  However, in FIG. 19 and FIG. 20 to FIG. 22, only one phase may be detected (three-phase modulation phase 30 degrees, etc.).

  In this case, it is necessary to detect two phases by increasing or decreasing the ON period of some upper arm switching elements (hereinafter referred to as energization adjustment).

  There is an unambiguous relationship between the phase current that can be detected and the phase. For this reason, when detecting two phases, the U-phase and V-phase currents are around 60 degrees and the V-phase is around 180 degrees. It is necessary to control the W-phase current so as to detect the W-phase and U-phase currents in the vicinity of the phase of 300 degrees.

  Further, it is necessary to detect the output (current value) of the power supply shunt resistor 6 for two phases in order (in time series) at a specific timing within the carrier cycle. That is, regarding two-phase modulation, as shown in FIG. 24, the fact that the phase currents of the W phase and the U phase can be detected is specified around the phase of 120 degrees. For this reason, control similar to three-phase modulation is required.

Further, a method different from the above method for detecting the phase current using the shunt resistor has been proposed. (For example, see Patent Document 3)
This method will be described below (hereinafter referred to as shunt method 2).

  FIG. 25 shows an inverter device and its peripheral circuits. The control circuit 13 of the inverter device 22 includes a U-phase lower arm shunt resistor 15 provided between the U-phase lower arm and the ground, a V-phase lower arm shunt resistor 16 provided between the V-phase lower arm and the ground, W The current is calculated by the voltage from the W-phase lower arm shunt resistor 17 provided between the lower arm and the ground.

  FIG. 26 shows the ON period (Duty) of the lower arm switching elements X, Y, and Z corresponding to FIG. However, in order to simplify the display as in the timing chart, the dead time for preventing a short circuit between the upper arm switching element and the lower arm switching element is omitted.

  The ON period of the U-phase lower arm switching element X is represented by a thin solid line, the ON period of the V-phase lower arm switching element Y is represented by a solid solid line, and the ON period of the W-phase lower arm switching element Z is represented by a thick solid line. ing. Further, the upper circulation period is indicated by a thin broken line arrow, and the lower circulation period is indicated by a thick broken line arrow.

  Similarly, FIG. 27 shows FIG. 20, FIG. 28 shows FIG. 21, and FIG. 29 shows FIG. 22 showing ON periods (Duty) of the corresponding lower arm switching elements X, Y, Z, respectively.

The current flows through the U-phase lower arm shunt resistor 15 (the current can be detected) while the lower arm switching element X is ON, and the current flows through the V-phase lower arm shunt resistor 16 (the current can be detected). The current flows through the W-phase lower arm shunt resistor 17 during the ON period of the lower arm switching element Y (the current can be detected) during the ON period of the lower arm switching element Z.

  Therefore, in FIG. 26 with 50% modulation, all three phases can be detected, but in FIGS. 27 to 29 with 100% modulation, one phase may not be detected. There is a unique relationship between them.

  Thus, near the phase of 90 degrees, the V-phase and W-phase currents (FIG. 27), near the phase of 210 degrees, the W-phase and U-phase currents (FIG. 28), and around the phase of 330 degrees, It is necessary to perform control so as to detect U-phase and V-phase currents (FIG. 29).

With respect to the two-phase modulation, FIG. 30 shows the ON periods (Duty) of the lower arm switching elements X, Y, and Z corresponding to FIG. In the vicinity of the phase of 120 degrees in FIG. 30, the detected phase current is specified as the V phase and the W phase. For this reason, the same control as the three-phase modulation is required for the two-phase modulation.
Japanese Unexamined Patent Publication No. 2000-333465 (page 9, FIG. 2) JP 2003-189670 A (page 2, claim 2, page 14, FIG. 1, page 15, FIG. 9) JP 2003-284374 A (page 7, FIG. 1)

  As described above, in the conventional phase current detection method for an inverter device, the shunt method 1 and the shunt method 2 have a unique relationship between the currents and phases that can be detected compared to the direct detection method. . Therefore, it is necessary to specify the current detected for each phase, and the control software becomes complicated.

  In the shunt method 1, if only one phase can be detected, energization adjustment is necessary to detect two phases. In addition, it is necessary to detect currents for two phases in time series within the carrier period. This further complicates the control software.

  The present invention solves such a conventional problem, and it is simple control software that does not require detection current identification for each phase, adjustment of energization, and time-series current detection, and detection of phase current by shunt resistance. An object of the present invention is to provide an inverter device.

  In order to solve the above-described problems, an inverter device according to the present invention includes three phases of an upper arm switching element connected to the positive side of a DC power source and a lower arm switching element connected to the negative side of the DC power source. In the inverter device that outputs a sinusoidal three-phase alternating current by switching the direct current voltage by PWM modulation, a power shunt resistor that detects the current between the direct current power source and the inverter device is provided, and the lower arm switching element and the direct current power source A lower arm shunt resistor for detecting the phase current of the relevant phase is provided for at least two phases between the negative arm and the phase current that cannot be detected by the lower arm shunt resistor.

  That is, when the lower arm shunt resistor is provided for three phases, the phase current for three phases can be detected.

  In addition, when the lower arm shunt resistance is provided for two phases, the phase current for the two phases of the phase provided with the lower arm shunt resistance can be detected.

  The phase current that may not be detected by the lower arm shunt resistance is the phase current that cannot be detected by the lower arm shunt resistance. Since it can always be detected by the resistance, it is not necessary to adjust the energization to detect the phase current. Therefore, the phase current that can be detected by the phase is not specified. The phase current can be detected individually by each shunt resistor instead of time series.

  Therefore, detection current identification for each phase, adjustment of energization, and time-series current detection are not required, and phase current detection using a shunt resistor can be performed with simple control software.

  The inverter device of the present invention can detect a phase current by a shunt resistor with simple control software that does not require detection current identification for each phase, adjustment of energization, and time-series current detection.

The first invention comprises three phases of an upper arm switching element connected to the positive side of the DC power supply and a lower arm switching element connected to the negative side of the DC power supply, and the DC voltage of the DC power supply is switched by PWM modulation. In the inverter device that outputs a sinusoidal three-phase alternating current, a power shunt resistor that detects a current between the DC power source and the inverter device is provided, and the phase is between the lower arm switching element and the negative side of the DC power source. The lower arm shunt resistor for detecting the phase current of two phases is provided, and the phase current of the phase is determined by the lower arm shunt resistor.
If the phase current cannot be detected, the phase current that cannot be detected is detected by the power shunt resistor.

  The phase current that may not be detected by the lower arm shunt resistance is the phase current that cannot be detected by the lower arm shunt resistance. Since it can always be detected by the resistance, it is not necessary to adjust the energization to detect the phase current. Therefore, the phase current that can be detected by the phase is not specified. Each phase current can be detected by each shunt resistor.

  As a result, an inverter device capable of detecting a phase current by a shunt resistor is obtained with simple control software that does not require detection current identification for each phase, adjustment of energization, and time-series current detection.

  When lower arm shunt resistors are provided for three phases, phase currents for three phases can be detected, so that it is not necessary to calculate the currents of the remaining phases from the current values for two phases, and the control software is further simplified.

According to a second invention , in the inverter device of the first or second invention, a sinusoidal three-phase alternating current is output to the sensorless DC brushless motor, and the rotor of the sensorless DC brushless motor is based on the detected phase current. Perform position detection.

  This inverter device is useful because it is necessary to detect the phase current of two or more phases for rotor position detection.

According to a third invention , in the inverter device of the second invention , the inverter device is mounted on an electric compressor driven by a sensorless DC brushless motor.

  The inverter device mounted on the electric compressor is limited in installation space, needs to be downsized, and needs vibration resistance against vibrations from the motor, so this inverter device that detects current by shunt resistance is useful. is there.

A fourth invention is an inverter device according to the first to third inventions , which is mounted on a vehicle. In the case of a vehicle, since the mounting space is limited, downsizing is required, and vibration resistance against vibration due to traveling is also required, the present inverter device that detects current by shunt resistance is useful.

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

(Embodiment 1)
FIG. 1 shows an inverter device 24 according to Embodiment 1 of the present invention and an electric circuit around it. 25 differs from FIG. 25 in the background art in that a power supply shunt resistor 6 is added and the control circuit 13 is changed to a control circuit 18, and the others are the same as those in FIG. Apply as is.

  The power shunt resistor 6 is provided on the negative side of the battery 1, and the lower arm shunt resistors 15, 16, and 17 are respectively connected between the switching elements X, Y, and Z of the lower arm and the negative side of the battery 1. Connected through.

  FIG. 2 shows the upper arm ON period, the energization period, the circulation period, the lower arm ON period, the upper circulation period, and the lower circulation period at a phase of 90 degrees of three-phase 100% modulation.

  In the lower arm, the switching element X does not have an ON period, but the switching element Y and the switching element Z have an ON period. Therefore, the V-phase phase current is reduced by the V-phase lower arm shunt resistor 16 to the W-phase phase current. Can be detected by the W-phase lower arm shunt resistor 17, respectively. In the upper arm, since the switching element U has only one phase ON period, the phase current of the U phase can be detected by the power supply shunt resistor 6.

  For this reason, the phase currents for the U, V, and W3 phases can be detected for each phase without adjusting the energization.

  FIG. 3 shows the upper arm ON period, the energization period, the circulation period, the lower arm ON period, the upper circulation period, and the lower circulation period in the phase 210 degrees of the three-phase 100% modulation.

  In the lower arm, the switching element Y does not have an ON period, but the switching element Z and the switching element X have an ON period. Therefore, the W-phase phase current is reduced by the W-phase lower arm shunt resistor 17 to the U-phase phase current. Can be detected by the U-phase lower arm shunt resistor 15. In the upper arm, since the switching element V has only one phase ON period, the phase current of the V phase can be detected by the power supply shunt resistor 6.

  For this reason, the phase currents for the U, V, and W3 phases can be detected for each phase without adjusting the energization.

  FIG. 4 shows the upper arm ON period, the energization period, the circulation period, the lower arm ON period, the upper circulation period, and the lower circulation period in a three-phase 100% modulation phase of 330 degrees.

  In the lower arm, the switching element Z does not have an ON period, but the switching element X and the switching element Y have an ON period. Therefore, the U-phase phase current is caused by the U-phase lower arm shunt resistor 15 to cause the V-phase phase current. Can be detected by the V-phase lower arm shunt resistor 16, respectively. Further, in the upper arm, since the switching element W has a single ON period for only one phase, the phase current of the W phase can be detected by the power supply shunt resistor 6.

  For this reason, the phase currents for the U, V, and W3 phases can be detected for each phase without adjusting the energization.

  FIG. 5 shows the upper arm ON period, the energization period, the circulation period, the lower arm ON period, the upper circulation period, and the lower circulation period in the phase 120 degrees of the two-phase 100% modulation.

  In the lower arm, the switching element X does not have an ON period, but the switching element Y and the switching element Z have an ON period. Therefore, the V-phase phase current is reduced by the V-phase lower arm shunt resistor 16 to the W-phase phase current. Can be detected by the W-phase lower arm shunt resistor 17, respectively. In the upper arm, since the switching element U has only one phase ON period, the phase current of the U phase can be detected by the power supply shunt resistor 6.

  For this reason, the phase currents for the U, V, and W3 phases can be detected for each phase without adjusting the energization.

  The other phases are the same for the two-phase 100% modulation, and the description is omitted.

  As described above, in the lower arm, there is only one switching element in which the ON period disappears, that is, only one phase cannot detect the phase current.

  On the other hand, the upper arm switching element of the corresponding phase of the lower arm switching element in which the ON period disappears enters the full ON period of the carrier cycle. In the lower arm, the upper arm switching element of the two-phase phase that is the ON period is in the OFF period. Therefore, the upper arm switching element of the phase of the lower arm switching element in which the ON period disappears can have a single ON period of only the phase.

  Accordingly, there is only one lower arm switching element in which the ON period disappears, and the upper arm switching element in the phase of the lower arm switching element in which the ON period disappears can have a single ON period of only the phase. The phase current that cannot be detected by the power source can always be detected by the power supply shunt resistor 6, and therefore can always be detected for each phase without any current adjustment regardless of the phase.

As a result, an inverter device capable of detecting a phase current by a shunt resistor is obtained with simple control software that does not require detection current identification for each phase, adjustment of energization, and time-series current detection.

  If lower arm shunt resistors are provided for all three phases, current detection is possible for all three phases within one carrier, eliminating the need to calculate the current of the remaining phases from the current values for the two phases. It becomes even easier.

  FIG. 6 shows a flowchart of a current detection procedure based on the above-described current detection method.

  In step 10, the U-phase phase current is detected by the U-phase lower arm shunt resistor 15. If it can be detected, the process proceeds to step 20. If not detected, the process proceeds to step 11, the phase current of the U phase is detected by the power supply shunt resistor 6, and the process proceeds to step 20.

  In step 20, the V-phase phase current is detected by the V-phase lower arm shunt resistor 16. If it can be detected, the process proceeds to step 30. If not detected, the process proceeds to step 21, the phase current of the V phase is detected by the power supply shunt resistor 6, and the process proceeds to step 30.

  In step 30, the W-phase phase current is detected by the W-phase lower arm shunt resistor 17. If it can be detected, the process ends. If not detected, the process proceeds to step 31, and the phase current of the W phase is detected by the power supply shunt resistor 6 and the process ends.

  Based on these detected current values, the induced voltage of the magnet rotor 5 constituting the motor 11 is calculated, and its position is detected.

  As described above, current detection can be performed with a simple and clear flow.

  In the above flowchart, the phase current detection order is not limited to this. The phase current detection timing may be either the first half or the second half of the carrier cycle.

(Embodiment 2)
FIG. 7 shows an inverter device 23 according to the second embodiment of the present invention and its surrounding electric circuit. The difference from FIG. 1 in the first embodiment of the present invention is that the W-phase lower arm shunt resistor 17 is deleted and the control circuit 18 is changed to the control circuit 14. It is the same as FIG. 1, and the reference numerals and the like are applied as they are.

  With the above-described configuration, the U-phase and V-phase phase currents provided with the lower arm shunt resistors 15 and 16 can always be detected for each phase independently, without energization adjustment, regardless of the phase.

  Further, since the phase currents for two phases to be detected are fixed to the U phase and the V phase, the change from the direct detection method for detecting the U phase and V phase currents shown in FIG. Since control software can be shared with others, it is easy.

  The number of shunt resistors is three, that is, two lower arm shunt resistors and one power supply shunt resistor, which is the same as the conventional shunt method 2. Therefore, an increase in the number of parts and an increase in shape can be prevented.

  Since the current supplied from the power source flows through the power shunt resistor 6, the maximum current always flows. Moreover, it is a direct current. Therefore, power calculation, maximum current detection and protection are facilitated using the power supply shunt resistor 6 as compared with the conventional shunt method 2.

Furthermore, the phase 60 degrees of the three-phase 100% modulation in FIG. 20 and the phase 60 of the three-phase 100% modulation in FIG.
In comparison, the power source shunt resistor 6 can detect the U-phase and V-phase currents, the U-phase lower arm shunt resistor 15 can detect the U-phase phase current, and the V-phase lower arm shunt resistor 16 can detect the V-phase current. It can be seen that the phase current of the phase can be detected. Thereby, the current detection circuit including the shunt resistor can be diagnosed by comparing the detected current value by the lower arm shunt resistor and the detected current value by the power source shunt resistor 6 (power source shunt resistor).

  FIG. 8 shows a flowchart of a current detection procedure based on the above-described current detection method.

  In step 10, the U-phase phase current is detected by the U-phase lower arm shunt resistor 15. If it can be detected, the process proceeds to step 20. If not detected, the process proceeds to step 11, the phase current of the U phase is detected by the power supply shunt resistor 6, and the process proceeds to step 20.

  In step 20, the V-phase phase current is detected by the V-phase lower arm shunt resistor 16. If it can be detected, the process proceeds to step 50. If not detected, the process proceeds to step 21, the phase current of the V phase is detected by the power supply shunt resistor 6, and the process proceeds to step 50.

  In step 50, the W-phase current is calculated from the detected U-phase current and V-phase current (Kirchhoff's current law is applied at the neutral point of the stator winding 4).

  Based on these detected current values, the induced voltage of the magnet rotor 5 constituting the motor 11 is calculated, and its position is detected.

  As described above, current detection can be performed with a simple and clear flow.

  In the above flowchart, the phase current detection order is not limited to this. The phase current detection timing may be either the first half or the second half of the carrier cycle.

  Although two shunt resistors are required, the U-phase lower arm shunt resistor 15, the V-phase lower arm shunt resistor 16, the V-phase lower arm shunt resistor 16, the W-phase lower arm shunt resistor 17, and the W-phase. Any combination of the lower arm shunt resistor 17 for use and the lower arm shunt resistor 15 for U phase may be used.

(Embodiment 3)
FIG. 9 shows a view in which the inverter device 23 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 compressed by the compression mechanism 28 (scroll in this example) being driven 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.

  The inverter device 23 (or the inverter device 24) uses the case 30 so that it can 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. A terminal 39 connected to the winding of the motor 11 inside the electric compressor 40 is connected to the output unit of the inverter circuit unit 10. The connection line 36 fixed to the inverter device 23 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.

  Such an inverter device-integrated electric compressor is suitable as an embodiment of the present invention because the inverter device 23 is required to be small and resistant to vibration.

  In each of the above embodiments, the DC power source is a battery. However, the present invention is not limited to this, and a DC power source obtained by rectifying a commercial AC power source may be used. Although the motor 11 is a sensorless DC brushless motor, it can also be applied to a reluctance motor, an induction motor, or the like.

  In addition, although the case of three phases has been described as an example, it can also be applied to multiphase.

  As described above, the inverter device according to the present invention can be applied to various consumer products and various industrial devices because it is simple control software and is small in size and capable of detecting phase current with high vibration resistance. The load can be applied to AC devices other than motors.

The inverter apparatus which concerns on Embodiment 1 of this invention, and its surrounding electric circuit diagram Explanatory diagram of current detection at 90 degree phase of 3-phase 100% modulation Explanatory drawing of current detection at a phase of 210 degrees of three-phase 100% modulation Explanatory diagram of current detection at a phase of 330 degrees for 3-phase 100% modulation Explanatory drawing of current detection at phase 120 degrees of 2-phase 100% modulation The flowchart which shows the electric current detection procedure which concerns on Embodiment 1 of this invention. The inverter apparatus which concerns on Embodiment 2 of this invention, and its surrounding electric circuit diagram The flowchart which shows the electric current detection procedure which concerns on Embodiment 2 of this invention. Sectional drawing of the inverter apparatus integrated electric compressor which concerns on Embodiment 3 of this invention. Inverter device that directly detects phase current and surrounding electric circuit diagram Inverter device that detects phase current with shunt resistance of power line and electrical circuit diagram around it Characteristic diagram showing modulation of each phase waveform in 3-phase 50% modulation Characteristic diagram showing modulation of each phase waveform in 3-phase 100% modulation Three-phase modulation timing chart Electrical circuit diagram showing current path in period (a) Electrical circuit diagram showing current path in period (b) Electrical circuit diagram showing current path in period (c) Electrical circuit diagram showing current path in period (d) Characteristic diagram showing the ON period, energization period, and circulation period of the upper arm in the phase of 30 to 90 degrees of 3-phase 50% modulation Characteristic diagram showing the ON period, energization period, and circulation period of the upper arm at a phase of 30 degrees to 90 degrees of 3-phase 100% modulation Characteristic diagram showing the ON period, energization period, and circulation period of the upper arm in the three-phase 100% modulation phase of 150 to 210 degrees Characteristic diagram showing the ON period, energization period, and circulation period of the upper arm in the phase 270 to 330 degrees of the three-phase 100% modulation Characteristic diagram showing modulation of each phase waveform in 2-phase 100% modulation Characteristic diagram showing the ON period, energization period, and circulation period of the upper arm in the phase of 90 ° to 150 ° of 2-phase 100% modulation Inverter device that detects phase current by three shunt resistors between the lower arm and ground, and the electrical circuit diagram around it Characteristic chart showing lower arm ON period, upper circulation period, and lower circulation period in 30-90 degree phase of 3-phase 50% modulation Characteristic chart showing lower arm ON period, upper circulation period, and lower circulation period in 30-90 degrees phase of 3-phase 100% modulation Characteristic diagram showing lower arm ON period, upper circulation period, and lower circulation period in three-phase 100% modulation phase 150 degrees to 210 degrees Characteristic diagram showing lower arm ON period, upper circulation period, and lower circulation period in 270 degrees to 330 degrees of three-phase 100% modulation phase Characteristic diagram showing lower arm ON period, upper circulation period, and lower circulation period in 90-150 degree phase of 2-phase 100% modulation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Switching element 3 Diode 4 Stator winding 5 Magnet rotor 6 Power supply shunt resistance 10 Inverter circuit 11 Sensorless DC brushless motor 15 U-phase lower arm shunt resistance 16 V-phase lower arm shunt resistance 17 W-phase lower arm Shunt resistor 23 Inverter device 24 Inverter device 40 Electric compressor

Claims (4)

The upper arm switching element connected to the positive side of the DC power source and the lower arm switching element connected to the negative side of the DC power source are provided in three phases, and the DC voltage of the DC power source is switched by PWM modulation to make a sine In the inverter device that outputs a wavy three-phase alternating current, a power shunt resistor that detects a current between the direct current power source and the inverter device is provided, and the phase is interposed between the lower arm switching element and the negative side of the direct current power source. An inverter device that provides two phases of lower arm shunt resistors for detecting a phase current of the current phase and detects the phase current that cannot be detected by the power source shunt resistance when the phase current of the phase cannot be detected by the lower arm shunt resistance. The inverter apparatus according to claim 1, wherein the sinusoidal three-phase alternating current is output to a sensorless DC brushless motor, and the position of the rotor of the sensorless DC brushless motor is detected based on the detected phase current. The inverter apparatus of Claim 2 mounted in the electric compressor which uses the said sensorless DC brushless motor as a drive source. The inverter apparatus as described in any one of Claims 1 thru | or 3 mounted in a vehicle.

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