JP5200569B2 - Inverter device - Google Patents

Description

  The present invention relates to an inverter device that detects a phase current by a current sensor provided between a DC power source. In particular, it is intended to reduce noise in positioning of the magnet rotor before operation.

  Conventionally, an inverter device that detects a phase current with a current sensor provided between a DC power supply and the like has been proposed (for example, see Patent Document 1). This will be described below when the motor is in operation. The state where the motor is driven and the rotor is rotating is defined as operation. FIG. 14 shows an inverter device and its surrounding electric circuit. The control circuit 12 of the inverter device 21 detects the phase current for two phases based on the voltage from the shunt resistor 6. The phase current for the remaining one phase is calculated from the two current values (Kirchhoff's current law is applied at the neutral point of the stator winding 4).

  Based on these current values, an induced voltage by the magnet rotor 5 constituting the sensorless DC brushless motor 11 (hereinafter referred to as a motor) is calculated, and its position is detected. Then, based on the position detection and communication speed command signal (not shown), the switching element 2 (IGBT, FET, transistor, etc.) constituting the inverter circuit 10 is controlled via the connection line 18. To do. As a result, the DC voltage from the battery 1 is switched by PWM modulation, and a sinusoidal AC current is output to the stator winding 4 constituting the motor 11. The diode 3 constituting the inverter circuit 10 serves as a circulation 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.

  FIG. 15 shows a waveform characteristic chart in 50% modulation of three-phase modulation. A U-phase terminal voltage 41, a V-phase terminal voltage 42, a W-phase terminal voltage 43, and a neutral point voltage 29 are shown. In the three-phase modulation, the modulation increases in both directions of 0% and 100% centering on Duty 50% as the modulation increases. 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.

  In FIG. 16, the ON periods (Duty) of the upper arm switching elements U, V, and W within one carrier (carrier cycle) in the phase of 270 to 330 degrees indicated by the broken line in FIG. 15 are displayed symmetrically from the center. ing. 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. This is generally realized by the timer function of the microcomputer. If the upper arm switching element of the same phase is ON, the lower arm switching element is OFF, and if the upper arm switching element is OFF, the lower arm switching element is ON. However, a dead time period is provided to prevent a short circuit between the upper arm switching element and the lower arm switching element.

  Although details of phase current detection by the shunt resistor 6 are omitted, it is possible to know the phase current flowing through the power supply line (shunt resistor 6) when the upper arm switching elements U, V, W are turned on and 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). Therefore, the detectable phase current can be known by confirming that the upper arm switching elements U, V, and W are ON. However, in the current detection by the shunt resistor 6, the ON time is required to be longer than the minimum predetermined time necessary for current detection (this predetermined time is defined as δ).

  Here, energization refers to a state in which power is supplied from the battery 1 to the inverter circuit 10 (motor 11), and non-energization refers to a state in which power is not supplied from the battery 1 to the inverter circuit 10 (motor 11). It is defined as In the non-energized state, the lower circulation is a state in which all of the lower arm switching elements X, Y, and Z are turned on and current is circulated between the lower arm and the motor 11, and the upper circulation is the upper arm switching. It is defined as a state in which all of the elements U, V, W are turned on and current is circulating between the upper arm and the motor 11.

  In FIG. 16, a period in which current detection by the shunt resistor 6 is possible is set as a detection period, and is indicated by a solid line arrow, and indicates the phase of the current detected in the vicinity of the solid line arrow. In this case, the detection period of the U-phase current is indicated as U, and the detection period of the W-phase current is indicated as W.

  At the phase of 270 degrees, only the U-phase current can be detected. Further, at the phase of 330 degrees, only the W-phase phase current can be detected. An example of a response to the fact that only the phase current for one phase can be detected is shown in FIG. FIG. 17A shows the case of the phase of 330 degrees in FIG. 16 as it is. In FIG. 17B, a predetermined value δ is added to the ON period (Duty) of the upper arm switching element U in FIG. 17A so that the phase current of the V phase can also be detected. FIG. 17C shows a case where the ON period (Duty) of the upper arm switching element U in FIG. 17A is reduced by a predetermined value δ so that the U-phase phase current can also be detected. In this way, the addition or reduction to the original PWM ON period (Duty) so that the phase current can be detected is defined as energization correction. Further, the value to be added or reduced is defined as an energization correction amount. As a result, phase currents for two phases can be detected. By executing both FIG. 17B and FIG. 17C, the addition or reduction of the predetermined value δ of the ON period (Duty) of the upper arm switching element U is cancelled. That is, executing both FIG. 17B and FIG. 17C is equivalent to executing twice in FIG. 17A.

  Next, the positioning of the magnet rotor before the operation of the motor will be described below. In order to start the rotation of the magnet rotor 5, it is necessary to position the magnet rotor 5 before operation (see, for example, Patent Document 2). An example will be described below. FIG. 18A shows a case where the magnet rotor 5 is positioned with the U phase and V phase of the stator winding 4 as the S pole and the W phase as the N pole in the case of 4 poles. The N pole of the magnet rotor 5 is positioned on the S pole of the stator winding 4 and the S pole of the magnet rotor 5 is positioned on the N pole of the stator winding 4 so as to be opposed to each other. . At this time, as shown in FIG. 18B, current flows from the W phase to the U phase and the V phase of the stator winding 4.

  19 ((B) and (C)) and FIG. 20 ((B) and (C)), the ON period of the upper arm switching elements U, V and W within one carrier (carrier cycle) in the above-described positioning. (Duty) is displayed in the same manner as in FIGS. FIG. 21 shows the W-phase current from the positioning to the operation.

  FIG. 19A shows a case where the energization period is set small in order to gradually increase the current at the initial stage of positioning shown in FIG. The period from the start of positioning until the current rises is defined as the initial positioning. In the initial stage of positioning, this energization period is gradually increased. In this state, current detection by the shunt resistor 6 cannot be performed. The correspondence example for that is FIG. 19 (B) and FIG. 19 (C).

  In FIG. 19B, a predetermined value δ or more is added to the latter half (right side) of the ON period (Duty) of the upper arm switching element U in FIG. 19A so that the phase current of the U phase can be detected. Further, a predetermined value δ or more is added to the first half (left side) of the carrier period in the ON period (Duty) of the upper arm switching element W in FIG. 19A so that the phase current of the W phase can be detected. . Thereby, the phase current for two phases can be detected.

  In FIG. 19C, the ON period (Duty) of the upper arm switching element U and the upper arm switching element W in FIG. 19A is reduced by a predetermined value δ or more, and the U-phase phase current and the W-phase phase current are reduced. It can be detected. Thereby, the phase current for two phases can be detected. The reduction of the ON period (Duty) by a predetermined value δ or more cancels the addition of the ON period (Duty) by a predetermined value δ or more in FIG. That is, by executing both FIG. 19B and FIG. 19C, the PWM modulation result becomes equivalent to the two executions of FIG. 19A.

  By executing FIG. 19B and FIG. 19C, it is possible to increase the current in the initial positioning while detecting the phase currents for two phases. Then, at the initial stage of positioning, approximately 50 mS is executed. When the carrier frequency is 10 kHz and the carrier cycle is 100 μS, the carrier cycle is 500 times.

  FIG. 20A shows the case where the energization period is set so that a predetermined constant current flows in the stationary positioning period shown in FIG. A period in which the current is constant after the current rising at the initial stage of the placement is defined as a stationary positioning period. Compared to FIG. 17A during operation, the energization period is short, but this is because the magnet rotor 5 is stopped and no induced voltage is generated in the stator winding 4, and energization is performed to allow the same current to flow. This is because the period may be short. In this state, the current detection by the shunt resistor 6 can detect only the W-phase current. The correspondence example for that is FIG. 20 (B) and FIG. 20 (C). The method is basically the same as FIG. 17 during operation.

  In FIG. 20B, a predetermined value δ is added to the ON period (Duty) of the upper arm switching element U in FIG. 20A so that the phase current of the V phase can also be detected. Further, FIG. 20C shows a case where the ON period (Duty) of the upper arm switching element U in FIG. 20A is reduced by a predetermined value δ so that the U-phase phase current can also be detected. Thereby, the phase current for two phases can be detected. By executing both FIG. 20B and FIG. 20C, the addition or reduction of the predetermined value δ to the ON period (Duty) of the upper arm switching element U is cancelled.

  By executing FIG. 20B and FIG. 20C, a constant current in the stationary stationary phase can be passed while detecting the phase currents for two phases. Then, approximately 100 ms is executed. When the carrier frequency is 10 kHz and the carrier cycle is 100 μS, the carrier cycle is 1000 times.

FIG. 21 shows the W-phase phase current from positioning to operation. Positioning includes an initial stage in which the current gradually increases and a stationary period in which the current is constant. A sine wave alternating current during operation flows following the steady-state current. When the waveform of FIG. 15 is replaced with a sinusoidal alternating current (41 is a U-phase current, 42 is a V-phase current, 43 is a W-phase current), a phase of 330 degrees is a steady-state positioning current, that is, an operation start. Corresponds to current. The reason why the current in the stationary stationary phase is continued is to start up stably. This is because once the positioning current is turned off, the position of the positioned magnet rotor 5 may move. When the magnet rotor 5 starts rotating, an induced voltage is generated in the stator winding 4 by the magnet rotor 5 and the phase of the current with respect to the phase of the induced voltage is appropriately controlled. The current value of becomes smaller.
JP 2003-189670 (page 14, FIG. 1, page 16, FIG. 14) Japanese Patent Laid-Open No. 11-356088 (page 7, FIG. 6)

  As described above, in the phase current detection method with only one current sensor, the number of components is small compared to the method of directly detecting the phase current of each phase using two to three current sensors, so that the size can be reduced. There are advantages such as being able to improve the reliability of vibration resistance and the like.

  However, when the phase current for two phases cannot be detected, it is necessary to increase or decrease the ON period of the upper arm switching element in some phases (energization correction). By this energization correction, a ripple current is generated as compared with the original PWM modulation current. This ripple current becomes an electromagnetic force, which acts on the stator winding, the mechanism, the housing, etc. of the motor, and generates noise (vibration). The additional reduction in the ON period is canceled and the PWM modulation result does not change, but a ripple current is generated within the carrier period.

  In particular, at the time of positioning before the operation, the influence by the energization correction is large. For one thing, the magnet rotor does not rotate, so there is no operating noise, and noise caused by ripple current is easily noticeable. Secondly, the energization period is short (because the magnet rotor is stopped and no induced voltage is generated in the stator winding, and the energization period may be short to allow the same current to flow), and the energization correction amount is This is because it becomes relatively large (the minimum predetermined time δ necessary for detecting the current to be added or reduced relative to the original energization period of PWM modulation becomes relatively large). Especially in the initial stage of positioning, the energization period is shorter and the influence is larger than in the stationary positioning period. Third, when energization correction is not performed, only a specific phase (W phase) is connected to the positive side of the DC power supply, whereas when energization correction is performed, the other phases (U phase, V phase) are also DC power supplies. There is a moment when it is connected to the positive side, and the current ratio between the three phases changes momentarily. That is, the direction angle of the combined magnetic field due to the U phase, V phase, and W phase of the stator winding changes instantaneously. This is because the position of the magnet rotor fluctuates instantaneously to generate noise (vibration).

  The present invention solves such a conventional problem, and an object of the present invention is to reduce noise (vibration) at the time of positioning in an inverter device that detects a phase current by a current sensor arranged between a DC power source. And

  In order to solve the above problems, an inverter device according to the present invention includes an inverter circuit including an upper arm switching element connected to the plus side of a DC power supply and a lower arm switching element connected to the minus side, a DC power supply, A current sensor for detecting a current between the inverter circuits; and a control circuit for causing the inverter circuit to output a drive current to the sensorless DC brushless motor by PWM modulation. The control circuit is arranged in a magnet rotor positioning period before the motor is operated. In the state where the phase to which the positive side of the DC power source is applied is fixed during energization, the energization is corrected, and control is performed to detect the phase current for one phase by the current sensor. With this configuration, the direction angle of the combined magnetic field by the stator windings U phase, V phase, and W phase is fixed without fluctuation. Thereby, the vibration noise of a magnet rotor is prevented. That is, it is possible to suppress noise during positioning that is greatly affected by the energization correction. In addition, since the ratio of each phase current of the U phase, V phase, and W phase is fixed, the phase current of the other phase can be calculated by detecting only the phase current of one phase.

  The inverter device of the present invention can detect a phase current by a single current sensor while suppressing noise during positioning by energization correction, and can perform stable start-up.

  According to a first aspect of the present invention, there is provided an inverter circuit including an upper arm switching element connected to a positive side of a DC power source and a lower arm switching element connected to a negative side, and a current for detecting a current between the DC power source and the inverter circuit A sensor and a control circuit that outputs drive current to the sensorless DC brushless motor by PWM modulation in the inverter circuit are provided. The control circuit is applied with the positive side of the DC power supply during energization during the positioning period of the magnet rotor before the motor is operated. The current is corrected in a state where the phase to be fixed is fixed, and control for detecting the phase current for one phase is performed by the current sensor. With this configuration, the direction angle of the combined magnetic field by the stator windings U phase, V phase, and W phase is fixed without fluctuation. Thereby, the vibration noise of a magnet rotor is prevented. That is, it is possible to suppress noise during positioning that is greatly affected by the energization correction. Further, since the ratio of each phase current of the U phase, V phase, and W phase is fixed, the phase currents of the other phases can be calculated by detecting only the phase current of one phase.

  According to a second aspect of the present invention, in the inverter device of the first aspect of the present invention, a period during which the energization correction is not performed is provided, and the phase current is detected by the energization correction during the period in which the detection of the phase current is reflected in the PWM modulation during operation. It is. By providing a period during which the energization correction is not performed, noise during positioning can be suppressed. In addition, the control circuit software can be simplified. In the period in which the detection of the phase current can be reflected in the PWM modulation during operation, the current and the phase are continuously detected from the positioning by detecting the phase current by the energization correction, and stable start-up can be performed.

  According to a third invention, in the inverter device of the second invention, the PWM modulation is corrected based on the temperature of the motor during a period in which the energization correction is not performed. As a result, even during a period in which the current correction based on the current detection cannot be performed, the current flowing through the motor can be set to a predetermined value regardless of the motor temperature. Therefore, reliable positioning can be performed.

  According to a fourth aspect of the present invention, in the inverter device according to the first to third aspects of the invention, the PWM modulation is three-phase modulation. Compared to the two-phase modulation, the three-phase modulation has a smooth current waveform and low noise, so that noise caused by the ripple current at the time of current correction is conspicuous and the effect of the present invention is great.

  According to a fifth aspect of the invention, in the inverter device according to the first to fourth aspects of the invention, the motor of the electric compressor is driven. Since electric compressors are used in room air conditioners, car air conditioners, etc., their noise is easily recognized. Therefore, the effect of the present invention that can reduce noise is great. Moreover, in an electric compressor, in order to protect a motor and a refrigerating cycle, a temperature sensor is often provided near the motor and near the refrigerant discharge port. The motor temperature and the refrigerant discharge temperature are close to each other, and the refrigerant discharge temperature can be used instead of the motor temperature. Therefore, it is not necessary to newly provide a motor temperature sensor or the like in the PWM modulation correction based on the motor temperature during a period in which the energization correction is not performed.

  According to a sixth invention, in the inverter device of the fifth invention, the electric compressor is a high pressure type. In the high-pressure electric compressor, the motor is cooled by the compressed high-temperature and high-pressure refrigerant. Therefore, the temperature of the motor becomes high. Therefore, the effect of the PWM modulation correction based on the motor temperature during the period in which the energization correction is not performed is great.

  According to a seventh invention, in the inverter device of the fifth or sixth invention, the temperature of the motor is substituted by the temperature of the inverter device mounted on the electric compressor. In the inverter-integrated electric compressor, the temperature of the motor and the temperature of the inverter device are close to each other if the startup temperature is balanced. In many cases, an inverter device is provided with a temperature sensor for protection of a switching element or the like. Therefore, it is not necessary to newly provide a motor temperature sensor or the like in the PWM modulation correction based on the motor temperature during the period in which the energization correction is not performed. If the electric compressor is of a low pressure type, both the motor and the inverter device are cooled by the low-pressure refrigerant. Therefore, the temperature of the motor and the temperature of the inverter device are close to each other, and the temperature of the inverter device is easy to substitute.

  An eighth invention is an inverter device according to the first to seventh 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 running vibration is also required, this inverter device that detects current with a single current sensor such as a shunt resistor is useful. It is difficult to use a device such as a soundproof box due to restrictions such as mounting space and weight, and since the noise is easily recognized, the effect of the present invention that can reduce noise is great.

  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 22 according to Embodiment 1 of the present invention and an electric circuit around it. The control circuit 7 of the inverter device 22 detects the phase current based on the voltage from the shunt resistor 6.

  During operation, the control circuit 7 calculates the induced voltage of the stator winding 4 by the magnet rotor 5 constituting the motor 11 based on the detected phase current value, and detects the position of the magnet rotor 5. . Then, based on this position detection, rotation speed command signal (not shown), etc., the switching element 2 constituting the inverter circuit 10 is controlled, and the DC voltage from the battery 1 is switched by PWM modulation. An alternating current is output to the stator winding 4 of the motor 11.

  The diode 3 constituting the inverter circuit 10 serves as a circulation 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.

  The current sensor is not limited to the shunt resistor 6 and may be any sensor that can detect an instantaneous peak current, such as a current sensor using a Hall element. Further, it may be provided on the positive side of the power supply line. If it is a shunt resistor, it is easy to realize miniaturization and improvement of vibration resistance. 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 or the like, and controls each switching element. 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 energization at the time of positioning of the magnet rotor 5 before the operation of the motor 11 will be described below. About the electricity supply at the time of the driving | operation which the magnet rotor 5 of the motor 11 is rotating, it is the same as that of background art. FIG. 2A shows a case where the magnet rotor 5 is positioned with the U phase and V phase of the stator winding 4 set to the S pole and the W phase set to the N pole in the case of four poles. The N pole of the magnet rotor 5 is positioned on the S pole of the stator winding 4 and the S pole of the magnet rotor 5 is positioned on the N pole of the stator winding 4 so as to be opposed to each other. . At this time, as shown in FIG. 2B, the control circuit 7 controls the switching element 2 so that current flows from the W phase to the U phase and the V phase of the stator winding 4.

  In the present embodiment, the phase to which the positive side of battery 1 is applied when energized is fixed to the W phase. Thereby, the ratio of each phase current of U phase, V phase, and W phase is fixed. In this case, the phase current of U phase: phase current of V phase: phase current of W phase = 1: 1: 2. And the direction angle of the synthetic magnetic field by the U-phase, V-phase, and W-phase of the stator winding 4 is fixed without fluctuation. Thereby, noise is prevented without magnet rotor 5 vibrating. Further, since the ratio of each phase current of the U phase, the V phase, and the W phase is fixed, the U phase current and the V phase current can be calculated by detecting only the W phase current.

  FIG. 3A shows an example of energization at the initial stage of positioning. 3B increases the ON period (Duty) of the upper arm switching element W in FIG. 3A (the ON periods of the upper arm switching elements U and V may be decreased). The ON period is slid to coincide with the ON periods of the other switching elements in the second half (right side) of the carrier cycle. As a result, the energization period is ensured by a predetermined value δ or more so that the W-phase current can be detected. FIG. 3 (C) shows a case in which the ON period (Duty) of the upper arm switching element W increased in FIG. 3 (B) in FIG. 3 (A) is decreased. In this case, as a result, the ON periods of the switching elements coincide with each other for the three phases.

  By executing both FIG. 3B and FIG. 3C, the increase and decrease of the ON period (Duty) in the upper arm switching element W are cancelled. However, since the phase current cannot be detected in FIG. 3C, the detected value in FIG. 3B is used instead. Further, by reducing the ON period (Duty) of the upper arm switching element W, when the ON period of the switching element W becomes smaller than the other two phases, the switching time is divided into several carrier periods so as not to become smaller. This prevents the switching elements U and V from being turned on when energized.

  The switching element is turned on when energized (the positive side of the battery 1 is applied) only in the W phase. Thereby, the ratio of each phase current of U phase, V phase, and W phase is fixed. Since the ratio of each phase current of U phase, V phase, and W phase is fixed (phase current of U phase: phase current of V phase: phase current of W phase = 1: 1: 2), the phase of W phase If only the current is detected, the U-phase current (1/2 of the W-phase current) and the V-phase current (1/2 of the W-phase current) can also be calculated. And the direction angle of the synthetic magnetic field by the U-phase, V-phase, and W-phase of the stator winding 4 is fixed without fluctuation. Thereby, noise is prevented without magnet rotor 5 vibrating.

  FIG. 4A shows another energization example in the initial stage of positioning. Compared to FIG. 3A, the energization period is slightly longer. In FIG. 4B, the ON period (Duty) of the upper arm switching element W in FIG. 4A is slid to coincide with the ON periods of the other switching elements in the second half (right side) of the carrier cycle. Thereby, the phase current of the W phase can be detected. Since the switching element is turned on only during the energization only in the W phase, the operational effects are the same as described above.

  FIG. 5A shows another energization example in the initial stage of positioning. Compared to FIG. 4A, the energization period is slightly longer. FIG. 5B slides the ON period (Duty) of the upper arm switching element W in FIG. 5A so that the W-phase current can be detected in the first half (left side) of the carrier cycle. is there. Since the switching element is turned on during energization only in the W phase in both the first half (left side) and the second half (right side) of the carrier cycle, the operational effects are the same as described above.

  In FIG. 3B, FIG. 3C, FIG. 4B, and FIG. 5B, what is common is that the switching elements U to V are not turned ON when energized. . In the initial stage of positioning, as an example, approximately 50 mS is executed alone or in combination with the above energization examples.

  FIG. 6A shows an example of energization in the stationary stationary phase. The energization period is set so that a predetermined constant current flows. In this state, the phase current cannot be detected by the shunt resistor 6. Corresponding examples for this are shown in FIGS. 6B and 6C. That is, the positioning stationary period is constituted by FIG. 6 (B) and FIG. 6 (C).

  FIG. 6B increases the ON period (Duty) of the upper arm switching element W in FIG. 6A so that the W-phase current can be detected. In FIG. 6C, the ON period (Duty) of the upper arm switching element W increased in FIG. 6B in FIG. 6A is decreased. Then, the ON period of the switching element is slid so that the W-phase current can be detected in the first half (left side) of the carrier cycle. As a result, the ON period of other switching elements coincides with the second half (right side) of the carrier cycle.

  By executing both FIG. 6B and FIG. 6C, the increase / decrease in the ON period (Duty) in the upper arm switching element W is cancelled. Then, by repeatedly executing both FIG. 6B and FIG. 6C, it is possible to flow a constant current in the stationary stationary phase while detecting the phase current.

  Moreover, although it is the same as that of the above-mentioned initial stage of positioning, it is only the W phase that the switching element is ON when energized. Thereby, the ratio of each phase current of U phase, V phase, and W phase is fixed. Since the ratio of each phase current of U phase, V phase, and W phase is fixed (phase current of U phase: phase current of V phase: phase current of W phase = 1: 1: 2), the phase of W phase If only the current is detected, the U-phase current (1/2 of the W-phase current) and the V-phase current (1/2 of the W-phase current) can also be calculated. And the direction angle of the synthetic magnetic field by the U-phase, V-phase, and W-phase of the stator winding 4 is fixed without fluctuation. Thereby, noise is prevented without magnet rotor 5 vibrating.

  In the above embodiment, the phase to which the positive side of the battery 1 is applied when energized is fixed to the W phase, but it may be the U phase or the V phase. At this time, the above-described positioning phases are 330 degrees (W phase), 90 degrees (U phase), and 210 degrees (V phase), respectively. Further, it may be two phases of U phase and V phase, V phase and W phase, W phase and U phase. In this case, the detected phase currents are a W-phase current, a U-phase current, and a V-phase current, respectively. And the phase at the time of the above-mentioned positioning will be 150 degree | times, 270 degree | times, and 30 degree | times, respectively.

  The phase of the S pole N pole of the stator winding 4 illustrated in FIG. 2 is arbitrary and can be applied to two poles, six poles, and the like. Although FIG. 6B and FIG. 6C are shown as the phase current detection method in the stationary stationary phase, the method of FIG. 5B may be used. The energization correction for detecting the phase current is not limited to the above, and is arbitrary as long as the phase to which the positive side of the battery 1 is applied during energization is fixed. During the original energization period of the PWM modulation, the DC voltage of the battery 1 may be detected, and the current accuracy may be increased by adjusting (multiplying the reciprocal of the ratio) according to the ratio to the reference voltage.

  Also, during the magnet rotor positioning period, the phase to which the positive side of the DC power supply is applied when energized is fixed to the W phase. However, within the magnet rotor positioning period, for example, the phase is fixed to the U phase and then fixed to the V phase. Positioning may be performed multiple times to improve positioning accuracy, such as two-step positioning.

(Embodiment 2)
In the first embodiment, vibration of the magnet rotor is prevented and noise is suppressed. On the other hand, the current ripple due to the energization correction is small because the current detection is only for one phase but occurs. For this reason, in this embodiment, unless necessary, current correction for current detection is not performed.

  As an example of the initial stage of positioning, the energization period is gradually increased as shown in FIGS. 7A, 7B, and 7C. Here, the time until the current has risen (initial positioning) is 50 mS. In this period, since the energization period is set to be shorter than that in the stationary period, the effect on noise is even greater when the energization correction is performed. For this reason, the current rising period at the initial stage of positioning is set as a period during which no energization correction is performed. Thereby, the software of the control circuit can be simplified.

  As a numerical example, the DC voltage of the battery 1 is DC 300 V, the resistance value of each phase of the stator winding 4 is 1Ω, and the carrier frequency is 10 kHz (carrier cycle 100 μS). Here, in order to set the phase current value of the W-phase in the stationary positioning period to 18 A, the equivalent resistance value of the stator winding 4 is 1.5Ω (see FIG. 2B), so it is necessary to apply a DC 27V equivalent. is there. DC27V is 9% of DC300V. Therefore, the duty of the energization period may be 9% (9 μS).

  Therefore, at the initial stage of positioning, the duty of the energization period is gradually increased from 0% to nearly 10%. 7A is 2.5% (2.5 μS), FIG. 7B is 5% (5 μS), and FIG. 7C is 7.5% (7.5 μS). Yes. Since the energization period is divided into the first half (left side) and the second half (right side) of the carrier cycle (because of three-phase modulation), each energization period is 1.25 μS in FIG. In FIG. 7B, it becomes 2.5 μS, and in FIG. 7C, it becomes 3.75 μS.

  Here, if the minimum predetermined time δ necessary for current detection is 5 μS, current detection by the shunt resistor 6 cannot be performed. Therefore, assuming that energization correction is performed (assuming that the energization correction amount is 5 μS), the ratio of the energization correction amount to the original energization period of PWM modulation is four times (5 μS / 1.25 μS, FIG. In B), it is doubled (5 μS / 2.5 μS), and in FIG. 7C, it is 1.3 times (5 μS / 3.75 μS).

  On the other hand, since the duty in the stationary positioning period is 4.5% (4.5 μS), it is as small as 1.1 times (5 μS / 4.5 μS). Accordingly, at the initial stage of positioning, a large ripple current is added to the current due to the original PWM modulation.

  On the other hand, phase current detection is performed in the stationary positioning period. FIG. 8 shows the W-phase current from positioning to operation. When the waveform of FIG. 15 is replaced with a sinusoidal alternating current (41 is a U-phase current, 42 is a V-phase current, 43 is a W-phase current), the phase 330 degrees is the current at the end of the stationary phase, that is, the operation start Is equivalent to In the steady period, phase current is detected by energization correction (in some cases, energization correction is not necessary), and further, the above phase is taken into account, and PWM modulation during operation is calculated (reflected in PWM modulation during operation). Thereby, the sine wave alternating current at the time of operation flows continuously from the current in the stationary positioning period (in the direction in which the phase increases from 330 degrees). Therefore, the current and phase are continuous from the positioning, and stable start-up can be performed.

  It can be considered that the phase current detection in the stationary positioning period is limited to a necessary period. FIG. 9A is the same as FIG. 6A and shows a case where the energization period is set so that a predetermined constant current flows in the stationary positioning period. This is performed for 99 mS out of 100 mS in the stationary stationary phase. This period is a period during which energization correction is not performed.

  9B and 9C are the same as FIG. 6B and FIG. 6C, but the implementation time is 1 mS. When the carrier frequency is 10 kHz and the carrier cycle is 100 μS, the carrier cycle is 10 times. Therefore, it is possible to secure a sufficient time to calculate the PWM modulation during operation from the phase current detected in the stationary positioning period. That is, the detection of the phase current can be reflected in the PWM modulation during operation. As described above, the stationary positioning period is configured by FIGS. 9A, 9B, and 9C. The period during which the energization correction is not performed is 149 mS (initial 50 mS, stationary period 99 mS) out of the positioning 150 mS (initial 50 mS, stationary period 100 mS).

  FIG. 10 shows the W-phase current from positioning to operation. Compared to FIG. 8, current detection starts from the end of the stationary stationary phase. In the positioning, the period other than the end of the stationary stationary period is a period in which the energization correction is not performed, that is, the phase current detection is not performed.

  Furthermore, the time period for performing the energization correction is shortened. That is, 99 mS in FIG. 9A is 99.8 mS, and 1 mS in FIGS. 9B and 9C is 0.2 mS. The energization correction at the end of the stationary positioning period is only 0.2 mS. In the case of a carrier frequency of 10 kHz and a carrier cycle of 100 μS, there are only two carrier cycles. Each of FIG. 9B and FIG. 9C is one carrier cycle.

  This will be described with reference to FIG. The two carrier cycles at the end of the stationary stationary phase are p1499 and p1500, the carrier cycle at the beginning of operation is m1, and the horizontal axis is time and is shown continuously. In the case of a carrier frequency of 10 kHz and a carrier cycle of 100 μS, positioning 150 mS corresponds to 1500 carrier cycles, so the carrier cycle at the final end of the positioning (stationary phase) is p1500.

  From the top of the figure, PWM output timing, PWM calculation timing, and current detection timing are shown. The phase current detected in the carrier cycle p1499 is used in the period of the carrier cycle p1500 for the calculation of the PWM output in the carrier cycle m1 together with the phase information (in this case, 330 degrees). That is, the phase current detected in the carrier cycle p1499 in positioning is reflected in the carrier cycle m1 during operation. Further, the phase current detected in the carrier cycle p1500 in positioning is reflected in the carrier cycle m2 following the carrier cycle m1 during operation.

  The period during which the energization correction is not performed is 149.8 mS (initial 50 mS, stationary period 99.8 mS) of positioning 150 mS (initial 50 mS, stationary period 100 mS), that is, 99.9%.

  When applied to FIG. 10, the current detection starts from the two carrier period at the end of the stationary stationary phase. In the last two carrier cycles in the stationary stationary period, the phase current is detected by energization correction, and the above-described phase is added to calculate (reflect) the PWM modulation during operation. Thereby, the sine wave alternating current at the time of operation flows following the current in the stationary stationary phase. Therefore, the current and phase are continuous from the positioning, and stable start-up can be performed.

  In the above embodiment, the case where the phase current detected in the carrier cycle p1499 is reflected in the carrier cycle m1 during operation has been described. However, the calculation speed is high due to the performance of the control circuit (such as a microcomputer). In some cases, it can be reflected by the carrier cycle p1500, and in some cases, the calculation speed can be reflected only when the carrier cycle is p1498.

(Embodiment 3)
In the present embodiment, as shown in FIGS. 3 to 7 and 9, PWM modulation is three-phase modulation. As described above, in the three-phase modulation, the energization period is divided into the first half (left side) and the second half (right side) of the carrier cycle. As a result, the PWM modulation, that is, the current change is divided into two in the first half (left side) and the second half (right side) of the carrier period. Therefore, the current waveform is smooth in the three-phase modulation as compared with the two-phase modulation in which the current change is not divided into two. As a result, since noise is reduced, noise caused by ripple current at the time of current correction is easily noticeable, and the effect of the present invention is enhanced.

(Embodiment 4)
FIG. 12 shows a diagram in which the inverter device 22 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 22 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. A terminal 39 connected to the stator winding 4 of the motor 11 inside the electric compressor 40 is connected to the output section of the inverter circuit section 10. The connection line 36 fixed to the inverter device 22 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.

  Since the electric compressor is used for a room air conditioner, a car air conditioner, etc., the noise is easily recognized by the user. Therefore, the effect of the present invention that can reduce noise is great. Moreover, in the inverter apparatus integrated electric compressor as described above, the inverter apparatus 22 needs to be small and resistant to vibration. Therefore, it is suitable as an embodiment of the present invention in which current is detected by a single current sensor such as a shunt resistor to realize low noise.

  In the above embodiment, the compression mechanism of the electric compressor is a scroll. However, the present invention is not limited to this. Moreover, although the compressed refrigerant showed about the high voltage | pressure type which cools a motor, a low voltage | pressure type may be sufficient.

(Embodiment 5)
In the electric compressor integrated with an inverter device of FIG. 12, a motor temperature sensor 8 for detecting the temperature of the motor is attached in the vicinity of the stator winding 4. An inverter temperature sensor 9 for detecting the temperature of the inverter is attached in the vicinity of the inverter circuit 10. When the temperature is balanced at the time of startup, the temperature of the motor detected by the motor temperature sensor 8 and the temperature of the inverter device detected by the inverter temperature sensor 9 are substantially equal. Therefore, when there is no motor temperature sensor 8, the inverter temperature sensor 9 can be substituted.

  As an example in the first embodiment, the energization period Duty of 10% (10 μS) is assumed to be when the motor temperature is 20 ° C. and the temperature coefficient of the resistance of the stator winding is 0.4% / ° C. If the temperature detected by the motor temperature sensor 8 or the inverter temperature sensor 9 is 70 ° C., the temperature rises from 20 ° C. to 50 ° C. The resistance value of the stator winding increases by 50 ° C. * 0.4% / ° C. = 20%. Therefore, in order to maintain the current value 20A, it is necessary to increase the energization period Duty by 20%. That is, the energization period may be set to Duty 12% (12 μS).

  In the present embodiment, the electric compressor 40 is a high pressure type. In the high-pressure electric compressor, the motor is cooled by the compressed high-temperature and high-pressure refrigerant. Therefore, the temperature of the motor becomes high. Therefore, the effect of the PWM modulation correction based on the motor temperature during the period in which the energization correction is not performed is great.

  In the above embodiment, the temperature sensor is a motor temperature sensor or an inverter temperature sensor. However, the temperature sensor is not limited to this and may be a discharge temperature sensor provided near the refrigerant discharge port.

(Embodiment 6)
FIG. 13 shows an example in which the inverter device of the present invention is configured integrally with a compressor (Embodiment 4) and applied to an air conditioner and mounted on a vehicle 60. The inverter device-integrated electric compressor 61, the outdoor heat exchanger 63, and the outdoor fan 62 are mounted in an engine room (or motor room) in front of the vehicle 60. On the other hand, an indoor fan 65, an indoor heat exchanger 67, and an air conditioner controller 64 are disposed in the vehicle compartment. Air outside the vehicle is sucked from the air inlet 66 and the air heat-exchanged by the indoor heat exchanger 67 is blown out into the vehicle interior.

  Vehicles, particularly electric vehicles and hybrid cars, are required to have a small and lightweight vehicle air conditioner from the viewpoint of ensuring running performance and mounting properties. Among them, there is a heavy weight, and in a narrow motor room (or engine room) Reduction in size and weight of the electric compressor mounted in other spaces is an important issue. In addition, when running with a motor, silence is high, and low noise is required for the electric compressor. It is also necessary to have vibration resistance against vibration during traveling.

  The inverter device of the present invention can achieve downsizing and vibration resistance and low noise by the configuration of one current sensor such as the shunt resistor 6 shown in the above embodiments. Therefore, the inverter device of the present invention is very suitable for these vehicles.

  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 rectified from a commercial AC power source may be used. Although the motor is a sensorless DC brushless motor, it can be applied to a motor that requires positioning, such as a reluctance motor. The present invention is not limited to sinusoidal driving, and can be applied to a driving method that requires detection of a phase current during positioning. Also in PWM two-phase modulation, there is no upper circulation and the same applies.

  As described above, the inverter device according to the present invention can detect a phase current with a single current sensor while suppressing noise due to energization correction at the time of positioning, and can perform stable start-up. In addition, since it is small and can improve reliability such as vibration resistance, it can be applied to various consumer products and various industrial equipment.

The inverter apparatus which concerns on Embodiment 1 of this invention, and its surrounding electric circuit diagram (A) Positional relationship diagram of stator winding and magnet rotor during positioning according to Embodiment 1 of the present invention, (B) Current explanatory diagram of stator winding during positioning (A) An explanatory view showing a first energization example in the initial stage of positioning, (B) an explanatory view showing an energization correction according to Embodiment 1 of the present invention, and (C) an explanatory view showing another energization correction. (A) Explanatory diagram showing a second energization example in the initial stage of positioning, (B) Explanatory diagram showing energization correction according to the first embodiment of the present invention. (A) Explanatory diagram showing a third energization example at the initial stage of positioning, (B) Explanatory diagram showing energization correction according to the first embodiment of the present invention. (A) An explanatory diagram showing an example of energization in a stationary positioning period, (B) an explanatory diagram showing an energization correction according to Embodiment 1 of the present invention, and (C) an explanatory diagram showing another energization correction. (A) 1st explanatory drawing which shows electricity supply in the positioning initial stage which concerns on Embodiment 2 of this invention, (B) 2nd explanatory drawing, (C) 3rd explanatory drawing Illustration of phase current of W phase from the same positioning to operation (A) Explanatory drawing which shows the example of electricity supply in the positioning regular period which concerns on Embodiment 2 of this invention, (B) Explanatory drawing which shows the same electricity supply correction | amendment, (C) Explanatory drawing which shows another electricity supply correction | amendment Illustration of phase current of W phase from the same positioning to operation Explanatory drawing of timing to reflect current detection during positioning to PWM modulation during operation Sectional drawing of the inverter apparatus integrated electric compressor which concerns on Embodiment 4 of this invention. Schematic diagram of a vehicle equipped with an inverter device according to Embodiment 5 of the present invention Inverter device for detecting phase current by current sensor between DC power supply and surrounding electric circuit diagram Waveform diagram showing modulation of each phase in maximum modulation 50% 3-phase modulation Characteristic chart showing upper arm ON period and detection period at phase 270 to 330 degrees with maximum modulation of 50% and 3-phase modulation (A) Explanatory diagram showing an example before energization correction during operation, (B) explanatory diagram showing the same energization correction, (C) explanatory diagram showing another energization correction (A) Positional relationship diagram of stator winding and magnet rotor during positioning, (B) Current explanation diagram of stator winding during positioning (A) Explanatory diagram showing an example before energization correction at the initial stage of positioning, (B) Explanatory diagram showing the same energization correction, (C) Explanatory diagram showing another energization correction (A) An explanatory view showing an example before energization correction in a stationary positioning period, (B) an explanatory view showing the same energization correction, and (C) an explanatory diagram showing another energization correction. Illustration of phase current of W phase from positioning to operation

Explanation of symbols

1 Battery 2 Switching Element 3 Diode 4 Stator Winding 5 Magnet Rotor 6 Shunt Resistance (Current Sensor)
7 Control Circuit 8 Motor Temperature Sensor 9 Inverter Temperature Sensor 10 Inverter Circuit 11 Sensorless DC Brushless Motor 22 Inverter Device 40 Electric Compressor (High Pressure Type)
60 vehicles

Claims (7)

An inverter circuit comprising 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; a current sensor for detecting a current between the DC power source and the inverter circuit; And a control circuit for outputting a drive current to the sensorless DC brushless motor by PWM modulation in the inverter circuit, and the control circuit applies the positive side of the DC power supply when energized during the magnet rotor positioning period before the motor is operated. An inverter device that performs control to correct the energization in a state in which a phase to be fixed is detected, and to detect a phase current for one phase by the current sensor ,
In the positioning period, a period in which the energization correction is not performed is provided, and in a period in which the detection of the phase current is reflected in PWM modulation during operation, the phase current is detected by the energization correction,
The period in which the energization correction is not performed is a current rising period in the initial positioning.
The period in which the detection of the phase current is reflected in the PWM modulation during operation is the stationary stationary period in which the current is constant after the initial rising of the positioning, and the phase current is calculated in order to calculate the PWM modulation during operation. An inverter device characterized in that it is a period for detection . The inverter apparatus according to claim 1, wherein the PWM modulation is corrected based on the temperature of the motor during a period in which the energization correction is not performed. The PWM modulation inverter apparatus according to claim 1 or 2 which is 3-phase modulation. The inverter apparatus according to any one of claims 1 to 3 for driving the motor of the electric compressor. The inverter device according to claim 4 , wherein the electric compressor is a high-pressure type. The inverter device according to claim 2 , wherein the temperature of the motor is substituted by the temperature of the inverter device mounted on the electric compressor . The inverter apparatus as described in any one of Claims 1-6 mounted in a vehicle.

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