JP6714169B2 - Compressor drive device, heat pump device, air conditioner and refrigerator - Google Patents

Description

The present invention relates to a compressor drive device that drives a compressor, a heat pump device that includes the compressor drive device, and an air conditioner and a refrigerator that include the heat pump device.

In an air conditioner and a refrigerator, a phenomenon is known in which refrigerant accumulates in a compressor having a large heat capacity while the apparatus is stopped in a low temperature state of outside air. This phenomenon is called "refrigerant stagnation" or, more simply, "sleeping". The refrigerant accumulated in the compressor dissolves in the lubricating oil in the compressor. As a result, the concentration of the lubricating oil is lowered and the viscosity of the lubricating oil is lowered. If the compressor is started in this state, low-viscosity lubricating oil may be supplied to the rotary shaft of the compressor or the compression section of the compressor, and sliding parts in the compressor may seize due to poor lubrication.

For the stagnation of the refrigerant, restrained energization is performed in which a current that is weaker than the drive current is applied to the driving motor of the compressor to heat the compressor and vaporize the liquid refrigerant. Various techniques have been conventionally proposed for restraint energization.

The following Patent Document 1 discloses a technique of supplying a high frequency low voltage to a compressor during an operation stop during heating.

Further, Patent Document 2 below discloses a technique of supplying a single-phase AC voltage having a higher frequency than that during normal operation to the compressor when a low ambient temperature of the air conditioner is detected.

Further, Patent Document 3 below discloses a technique of heating a motor winding by causing a copper loss in the motor winding by performing a restricted energization in which a direct current is applied to the driving motor of the compressor. Note that the restricted energization in which a direct current is caused to flow is also called “DC excitation type restricted energization”. There is also a method called "AC excitation type constraint energization" in which a heating current is generated by causing a copper loss and an iron loss in a motor winding by performing a constraint energization in which an alternating current is passed through a drive motor of a compressor.

Japanese Utility Model Laid-Open No. 60-68341 JP-A-61-91445 JP, 2007-166766, A

However, Patent Document 1 has a problem in that there is no detailed description of high-frequency low voltage and no specific means or method for smoothing the lubricating action inside the compressor is shown.

In addition, Patent Document 2 describes that a voltage is applied by a high-frequency single-phase AC power supply of about 25 kHz. Higher frequencies have the effect of suppressing noise by moving out of the audible range, suppressing vibration by moving out of resonance frequency, reducing the input and temperature rise by reducing the current due to the inductance of the winding, and suppressing rotation of the rotating part of the compressor. It is shown.

However, since the technique of Patent Document 2 is a high-frequency single-phase AC power source, as shown in FIG. 3 of this document, the entire OFF section in which all the switching elements are turned OFF occurs relatively long. .. At this time, the high-frequency current is regenerated to the DC power supply without returning to the motor through the freewheeling diode, the current in the off section decays quickly, the high-frequency current does not flow efficiently to the motor, and the heating efficiency of the compressor is poor. There is a problem of becoming. Further, the method of Patent Document 2 has the disadvantage of being subject to regulation by the Radio Law, since it is an alternating-current excitation-type constraint energization.

Moreover, in the said patent document 3, when performing restricted energization, the voltage command of the three-phase alternating current power supplied to a motor is two-phase modulation. In the case of two-phase modulation, one-phase switching of the three-phase voltage command is stopped. Therefore, there is a problem in that the driving of the six switching elements forming the inverter main circuit is biased, the load is concentrated on the specific switching element, and the life of the specific switching element is shortened.

The present invention has been made in view of the above, and a compressor drive device capable of efficiently heating refrigerant accumulated in a compressor while avoiding concentration of load on a specific switching element. The purpose is to get.

In order to solve the above-mentioned problems and achieve the object, a compressor drive device according to the present invention is a compressor drive device that performs constraint energization control for heating a drive motor of a compressor, by converting direct current into alternating current. Inverter main circuit for applying AC voltage to drive motor, DC voltage detector for detecting DC voltage applied to inverter main circuit, current detector for detecting current flowing in inverter main circuit, first for detecting outside air temperature Temperature detector, the second temperature detector that detects the temperature of the compressor, and PWM control of the switching element of the inverter main circuit based on the detection value of the DC voltage detector, the detection value of the current detector, and the carrier. An inverter control unit is provided. The inverter control unit determines the binding energization voltage based on the detection value of the DC voltage detector, the detection value of the first temperature detector, and the detection value of the second temperature detector, and based on the determined binding energization voltage. Then, the space vector in the space vector modulation method is calculated. The inverter control unit includes a first voltage vector and a second voltage vector that are two voltage vectors located on both sides of the calculated space vector, and a third voltage vector that is adjacent to the opposite side of the space vector based on the first voltage vector. And a fourth voltage vector located adjacently on the opposite side of the space vector based on the second voltage vector. The inverter control unit uses six voltage vectors obtained by adding the first and second zero vectors, which are two zero vectors, to the selected first, second, third, and fourth voltage vectors for one cycle of the carrier. Where, the first zero vector, the fourth voltage vector, the second voltage vector, the first voltage vector, the third voltage vector, the second zero vector, the second zero vector, the third voltage vector , The first voltage vector, the second voltage vector, the fourth voltage vector, and the first zero vector in this order to the inverter main circuit.

Advantageous Effects of Invention According to the present invention, it is possible to efficiently heat the refrigerant accumulated in the compressor while avoiding the concentration of the load on a specific switching element.

The figure which shows the structure of the heat pump apparatus to which the compressor drive device which concerns on Embodiment 1 is applied. Circuit diagram showing the configuration of the compressor drive device according to the first embodiment. Block diagram showing the configuration of the motor control unit in the first embodiment Block diagram showing the configuration of the PWM control unit in the first embodiment Diagram showing the definition of the inverter output voltage vector The figure which showed on the vector plane the relationship between the inverter output voltage vector in the space vector modulation system, and the ON or OFF state of the switching element of each phase upper arm. Flowchart showing a method of selecting a voltage vector for heating a refrigerant in the first embodiment FIG. 4 is a diagram for explaining a method of selecting a voltage vector for heating a refrigerant in the first embodiment. A time chart showing an example of a voltage command for generating a voltage vector selected according to FIG. 8 and a PWM signal generated by the voltage command. Schematically illustrates a state when heated by space vector located in the middle between the voltage vector V ₂ and the voltage vector V ₆ The figure which shows typically the mode when heating using the method of Embodiment 1. Block diagram showing an example of a hardware configuration for realizing the function of the motor control unit in the first embodiment FIG. 9 is a diagram for explaining a method of selecting a voltage vector for heating a refrigerant in the second embodiment. FIG. 7 is a diagram for explaining the output order of voltage vectors for refrigerant heating in the third embodiment. A circuit diagram showing a configuration of a compressor drive device according to a fourth embodiment. Flowchart for explaining the operation of the compressor drive device according to the fourth embodiment

Hereinafter, a compressor drive device, a heat pump device, an air conditioner, and a refrigerator according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

Embodiment 1.
FIG. 1 is a diagram showing a configuration of a heat pump device 100 to which the compressor driving device 30 according to the first embodiment is applied. The heat pump device 100 can be applied to an air conditioner and a refrigerator.

1, a heat pump device 100 includes a compressor 101 having a compression mechanism that compresses a refrigerant, a four-way valve 102 that changes the direction of a refrigerant gas, heat exchangers 103 and 104, an expansion mechanism 105, and a refrigerant pipe 106. Equipped with. The compressor 101, the four-way valve 102, the heat exchangers 103 and 104, and the expansion mechanism 105 are sequentially connected via a refrigerant pipe 106 to form a refrigeration cycle. The direction of the refrigerant gas is switched by the four-way valve 102. By switching the four-way valve 102 as shown by the solid line, the heat exchanger 103 becomes an evaporator and the heat exchanger 104 becomes a condenser. Also, by switching the four-way valve 102 as shown by the broken line, the heat exchanger 103 becomes a condenser and the heat exchanger 104 becomes an evaporator.

The compressor 101 includes a compression mechanism 107 that compresses a refrigerant and a motor 4 that operates the compression mechanism 107. The motor 4 is a three-phase motor having U-phase, V-phase, and W-phase three-phase windings. An AC voltage is applied to the motor 4 from the compressor drive device 30. That is, the motor 4 is driven by the compressor drive device 30.

FIG. 2 is a circuit diagram showing the configuration of the compressor drive device 30 according to the first embodiment. The compressor drive device 30 according to the first embodiment is a device that performs constraint energization control for eliminating the refrigerant stagnation of the compressor 101 by heating by energizing the motor 4 that is a driving motor of the compressor 101 by constraint energization. is there. As shown in FIG. 2, the compressor driving device 30 includes a DC power supply 1 that is a source of DC power, an inverter main circuit 2 that converts DC into AC and applies an AC voltage to a motor 4, and an inverter main circuit. And an inverter control unit 20 for controlling the control unit 2.

In the compressor drive device 30 shown in FIG. 2, the inverter main circuit 2 includes switching elements 5a to 5f and diodes 6a to 6f connected in parallel to the switching elements 5a to 5f. Of the switching elements 5a to 5f, the switching elements 5a, 5b and 5c are sometimes called upper arm switching elements, and the switching elements 5d, 5e and 5f are sometimes called lower arm switching elements.

The compressor drive device 30 is provided with a DC voltage detector 7 that detects the voltage of the DC power supply 1 applied to the inverter main circuit 2 and a current detector 8 that detects the current flowing through the inverter main circuit 2. .. An outside air temperature detector 51 that detects the outside air temperature is provided outside the compressor driving device 30. The compressor 101 is provided with a compressor temperature detector 52 that detects the temperature of the compressor 101. An example of the outside air temperature detector 51 and the compressor temperature detector 52 is a thermistor, and another example is a thermocouple. The outside air temperature detector 51 may be referred to as a "first temperature detector", and the compressor temperature detector 52 may be referred to as a "second temperature detector".

The voltage Vdc that is the voltage information detected by the DC voltage detector 7, the current Idc that is the current information detected by the current detector 8, the first temperature Te1 that is the detection value of the outside air temperature detector 51, and the compressor temperature detector. The second temperature Te2, which is the detected value of 52, is output to the inverter control unit 20. The transmission means to the inverter control unit 20 is arbitrary and may be wired or wireless.

The inverter control unit 20 includes a motor control unit 9 and a PWM control unit 10. The motor control unit 9 detects the stagnation of the refrigerant based on the first temperature Te1 which is the detection value of the outside air temperature detector 51 and the second temperature Te2 which is the detection value of the compressor temperature detector 52. The determination as to whether or not the refrigerant has fallen asleep is performed while the compressor 101 is stopped. It should be noted that the method for detecting the stagnation of the refrigerant is publicly known, and a detailed description thereof will be omitted here.

The PWM control section 10 switches the switching elements 5a to 5f of the inverter main circuit 2 based on the voltage Vdc which is the voltage information detected by the DC voltage detector 7 and the current Idc which is the current information detected by the current detector 8. Pulse width modulation (Pulse Width Modulation: hereinafter referred to as "PWM") signals UP, VP, WP, UN, VN, WN for driving the.

The PWM control unit 10 outputs the generated PWM signals UP, VP, WP, UN, VN, WN to the inverter main circuit 2. The switching elements 5a to 5f of the inverter main circuit 2 are driven by the PWM signals UP, VP, WP, UN, VN and WN. The inverter main circuit 2 controlled by the PWM control unit 10 applies the commanded AC voltage to the motor 4.

In the configuration shown in FIG. 2, the DC power supply 1 generally has a configuration in which the AC voltage of the AC power supply is converted into a DC voltage by an AC/DC converter. An example of the AC/DC converter is a rectifier circuit composed of a diode bridge. Another example of the AC/DC converter is a boost converter or a buck-boost converter circuit. A DC power supply represented by a solar cell or a battery may be directly used without using the AC/DC converter.

Further, in the configuration of FIG. 2, the current detector 8 is provided on the input side of the inverter main circuit 2, but the configuration is not limited to this. The current detector 8 may be provided between the inverter main circuit 2 and the motor 4. With this configuration, it is possible to detect the currents flowing in the respective phases of the motor 4, that is, the U phase, the V phase, and the W phase. The current detector 8 may be provided on the negative electrode side of the switching elements 5d to 5f. Also with this configuration, the current flowing in each phase of the motor 4 can be detected.

Next, the configurations and operations of the motor control unit 9 and the PWM control unit 10 will be described. First, FIG. 3 is a block diagram showing a configuration of the motor control unit 9 in the first embodiment. The motor control unit 9 includes a current restoration unit 11, a coordinate conversion unit 12, an estimation unit 13, a speed control unit 14, a current control unit 15, and a voltage command calculation unit 16.

The current restoration unit 11 restores the phase currents Iu, Iv, Iw flowing through the motor 4 from the current Idc which is the detection value of the current detector 8. When the phase currents Iu, Iv, Iw flowing through the motor 4 are directly detected, the restoration by the current restoration unit 11 is unnecessary.

The coordinate conversion unit 12 performs coordinate conversion to generate the d-axis current Id and the q-axis current Iq based on the restored phase currents Iu, Iv, Iw and the rotor magnetic pole position θ of the motor 4. The d-axis current Id is a current component in the d-axis direction on the dq coordinate axes. The q-axis current Iq is a current component in the q-axis direction on the dq coordinate axes. The rotor magnetic pole position θ is generated by the estimation unit 13. The d-axis current and the q-axis current converted by the coordinate conversion unit 12 are output to the estimation unit 13 and the current control unit 15.

The estimation unit 13 estimates the estimated speed value ω and the rotor magnetic pole position θ based on the d-axis current Id, the q-axis current Iq, the d-axis voltage command Vd*, and the q-axis voltage command Vq*. The d-axis voltage command Vd* and the q-axis voltage command Vq* are generated by the current controller 15. The estimated speed value ω estimated by the estimation unit 13 is output to the speed control unit 14. The rotor magnetic pole position θ estimated by the estimation unit 13 is output to the coordinate conversion unit 12 and the voltage command calculation unit 16 described above.

The speed control unit 14 calculates the q-axis current command Iq* such that the speed estimated value ω matches the speed command value ω*, based on the speed command value ω* and the speed estimated value ω. The q-axis current command Iq* calculated by the speed control unit 14 is output to the current control unit 15.

The current control unit 15 uses the d-axis voltage command Vd* such that the d-axis current Id matches the d-axis current command Id* and the q-axis voltage command such that the q-axis current Iq matches the q-axis current command Iq*. Vq* and are generated. The d-axis voltage command Vd* generated by the current control unit 15 is output to the estimation unit 13 and the voltage command calculation unit 16. The q-axis voltage command Vq* generated by the current control unit 15 is also output to the estimation unit 13 and the voltage command calculation unit 16.

The voltage command calculation unit 16 uses the voltage Vdc detected by the DC voltage detector 7, the d-axis voltage command Vd*, the q-axis voltage command Vq*, and the rotor magnetic pole position θ to determine the U-phase voltage command Vu* and the V-phase voltage. The command Vv*, the W-phase voltage command Vw*, and the voltage phase θv are generated. The U-phase voltage command Vu*, the V-phase voltage command Vv*, and the W-phase voltage command Vw* are voltage commands for each phase of UVW. The voltage phase θv is a reference phase angle when outputting the U-phase voltage command Vu*, the V-phase voltage command Vv*, and the W-phase voltage command Vw*.

FIG. 4 is a block diagram showing a configuration of PWM control unit 10 in the first exemplary embodiment. The PWM control unit 10 includes a carrier generation unit 17 and a carrier comparison unit 18. The carrier generation unit 17 generates carriers based on the voltage phase θv. The carrier comparison unit 18 generates PWM signals UP, VP, WP, UN, VN, WN based on the carrier and the voltage commands Vu*, Vv*, Vw*.

Next, a space vector modulation method for generating drive signals for the switching elements 5a to 5f of each phase by PWM modulation will be described with reference to FIGS. FIG. 5 is a diagram showing the definition of the inverter output voltage vector. FIG. 6 is a vector plane view showing the relationship between the inverter output voltage vector in the space vector modulation method and the ON or OFF state of the switching elements 5a, 5b, 5c of the upper arms of each phase. 5 and 6, when the switching elements 5a, 5b, 5c of the upper arms of each phase are in the on state, they are represented by "1", and when they are in the off state, they are represented by "0". The inverter output voltage vector is a vector when the output voltage applied to the inverter main circuit 2 is represented by a vector space in the space vector modulation method. In this sense, the inverter output voltage vector is also called “space vector”.

As shown in FIG. 5, there are two states of the switching elements 5a to 5f: "1" which is an on state and "0" which is an off state. Further, since the short-circuit current is prevented from flowing, the switching element of the upper arm and the switching element of the lower arm do not turn on at the same time. Therefore, eight types of voltage vectors shown in FIG. 5 can be defined for the combinations of the ON states and the OFF states of the switching elements 5a to 5f.

As described above, since the switching element of the lower arm has a dependent relationship with the switching element of the upper arm, the voltage vector can be represented by the state of the switching element of the upper arm. Therefore, the voltage vector is expressed in the form of "(state of switching element 5a of U-phase upper arm", "state of switching element 5b of V-phase upper arm", "state of switching element 5c of W-phase upper arm"). To At this time, the voltage vectors are V ₀ (000), V ₁ (001), V ₂ (010), V ₃ (011), V ₄ (100), V ₅ (101), V ₆ (110), V It can be expressed in eight ways, ₇ (111). Of these eight voltage vectors, V ₀ (000) and V ₇ (111) that have no magnitude are called zero vectors. Further, V ₁ (001), V ₂ (010), V ₃ (011), V ₄ (100), V ₅ (101), which are equal in magnitude and have a phase difference of 60° between adjacent vectors, V ₆ (110) is called the real vector.

In FIG. 6, between adjacent voltage vectors, the arrangement of the numerical values indicating the states of the switching elements is such that two changes do not occur at the same time. That is, between adjacent voltage vectors, the change from “0” to “1” or the change from “1” to “0” does not occur at the same time. Specifically, regarding V ₄ (100) and V ₆ (110), the switching element 5b changes from on to off or from off to on, and the states of the switching elements 5a and 5c do not change. In terms of V ₂ (010) and V ₃ (011), the switching element 5c changes from on to off or from off to on, and the states of the switching elements 5a and 5b do not change. Therefore, if the adjacent voltage vectors are sequentially selected according to the vector plane of FIG. 6, the states of the switching elements of a plurality of phases do not change at the same time. This suppresses the generation of noise or vibration due to the states of the switching elements of a plurality of phases changing simultaneously.

The motor control unit 9 can synthesize an arbitrary voltage command V* by arbitrarily combining the zero vectors V ₀ and V ₇ and the real vectors V _{1 to} V ₆ . The voltage command V* synthesized by the motor control unit 9 is converted into a U-phase voltage command Vu*, a V-phase voltage command Vv*, and a W-phase voltage command Vw*, which are three-phase voltage commands, and the voltage phase θv. At the same time, it is output to the PWM control unit 10. As described above, the PWM control unit 10 generates the PWM signals UP, VP, WP, UN, VN, WN based on the voltage commands Vu*, Vv*, Vw*.

Next, a method of generating the voltage command for heating the refrigerant in the first embodiment will be described with reference to the drawings of FIGS. 7 to 9. FIG. 7 is a flowchart showing a method of selecting a voltage vector for heating the refrigerant in the first embodiment. FIG. 8 is a diagram for explaining a method of selecting a voltage vector for heating the refrigerant in the first embodiment. FIG. 9 is a time chart showing an example of voltage commands Vu*, Vv*, Vw* for generating the voltage vector selected according to FIG. 8 and a PWM signal generated by the voltage commands Vu*, Vv*, Vw*. Is.

In the flow of FIG. 7, the processing of steps S101 to S107, S109, and S110 is executed by the motor controller 9, and the processing of step S108 is executed by the PWM controller 10.

In FIG. 7, in step S101, it is determined whether the compressor 101 is stopped. If the compressor 101 is not stopped (No in step S101), the determination process of step S101 is continued. If the compressor 101 is stopped (Yes in step S101), the process proceeds to step S102.

In step S102, the refrigerant stagnation amount is estimated. A method of estimating the refrigerant stagnation amount is known, and an outline thereof will be described here. The first temperature Te1 detected by the outside air temperature detector 51 and the second temperature Te2 detected by the compressor temperature detector 52 are used to estimate the refrigerant stagnation amount.

The refrigerant that circulates in the refrigeration cycle condenses and accumulates in the lowest temperature portion of the components that form the refrigeration cycle. Since the compressor 101 has the largest heat capacity among the components forming the refrigeration cycle, the second temperature Te2, which is the compressor temperature, increases with a delay with respect to the increase in the first temperature Te1, which is the outside air temperature. The lowest temperature. As a result, the liquid refrigerant stays inside the compressor 101. Therefore, the relationship between the first temperature Te1, the second temperature Te2, and the refrigerant stagnation amount is obtained in advance by experiments or simulations, and the obtained refrigerant stagnation amount is held as a table. By keeping it as a table, it is possible to refer to it at any time.

In addition, when the heat capacity of the compressor 101 is known in advance, only the first temperature Te1 is detected and it is estimated how much the temperature of the compressor 101 changes with respect to the change of the first temperature Te1. By doing so, the refrigerant stagnation amount per unit time can be estimated. In this case, the compressor temperature detector 52 can be eliminated and the cost can be reduced.

In step S103, it is determined whether or not the compressor 101 needs to be heated, that is, whether or not the compressor 101 needs to be heated. The refrigerant stagnation amount estimated in step S102 is used to determine whether heating is required. When it is determined that the heating is unnecessary (No in step S103), the process returns to step S101 and the process from step S101 is repeated. When it is determined that heating is necessary (Yes in step S103), the process proceeds to step S104.

In step S104, the constraint energization voltage ΣV is calculated. In step S105, a space vector based on the constraint energization voltage ΣV is selected. An example of the space vector based on the constraint energization voltage ΣV is shown in FIG. In the conventional DC excitation type restricted energization (see Patent Document 3 above), as shown in the figure, a space vector located in the middle between the voltage vector V ₂ and the voltage vector V ₆ is selected, and the space vector is used. Was heating up. As the space vector located in the middle, a vector having a direction in which the phase angle from the voltage vector V ₂ and the phase angle from the voltage vector V ₆ are equal is adopted.

On the other hand, in the first embodiment, the processes of steps S106 to S108 are added. In step S106, four voltage vectors are selected based on the space vector selected in step S105. In the example of FIG. 8, _four voltage vectors including the voltage vector V ₂ and the voltage vector V ₆ , the voltage vector V _3, and the voltage vector V ₄ are selected. The voltage vector V ₂ and the voltage vector V ₆ are real vectors located on both sides of the space vector representing the constraint energization voltage ΣV. Voltage vector V ₃ is a real vector located adjacent the opposite side of the space vector in a reference voltage vector V _2. The voltage vector V ₄ is an actual vector located adjacent to the opposite side of the space vector with respect to the voltage vector V ₆ . In the first embodiment, the space vector selected in step S105 does not have to be the space vector located in the middle between the voltage vector V ₂ and the voltage vector V _6, and the space vector in any direction You can choose.

In step S107, the output order of the six voltage vectors obtained by adding two zero vectors to the four voltage vectors selected in step S106 is determined. In the example of FIG. 8, six voltage vectors V ₀ , V ₂ , obtained by adding two zero vectors V ₀ , V ₇ to the selected four voltage vectors V ₂ , V ₃ , V ₄ , V ₆ The output order of V ₃ , V ₄ , V ₆ , and V ₇ is determined.

In FIG. 8, if six voltage vectors V ₀ , V ₂ , V ₃ , V ₄ , V ₆ , and V ₇ are selected counterclockwise, V ₀ →V ₄ →V ₆ →V ₂ →V It is selected in the order of ₃ →V ₇ . Further, in FIG. 8, if six voltage vectors V ₀ , V ₂ , V ₃ , V ₄ , V ₆ , and V ₇ are selected clockwise, V ₇ →V ₃ →V ₂ →V ₆ → It is selected in the order of V ₄ →V ₀ . The main points when selecting the voltage vector will be described later.

In step S108, the switching elements 5a to 5f are driven according to the output order determined in step S107. In step S109, the necessity of heating is determined again. When it is determined that heating is not necessary (No in step S109), the process proceeds to step S110. On the other hand, if it is determined that heating is necessary (Yes at Step S109), the process returns to Step S104, and the processing from Step S104 to Step S108 is repeated.

In step S110, heating is stopped. When the process of step S110 ends, the process returns to step S101. After that, the processing from step S101 to step S110 is repeated.

On the upper side of FIG. 9, an example of the voltage commands Vu*, Vv*, Vw* for generating the voltage vector selected according to FIG. 8 and the carrier are shown. Further, PWM signals UP, VP, WP generated by the voltage commands Vu*, Vv*, Vw* shown on the upper side are shown on the lower side of FIG.

In FIG. 9, a U-phase voltage command Vu*, a V-phase voltage command Vv*, and a W-phase voltage command Vw* are shown. The U-phase voltage command Vu* is a voltage command that changes so as to take a positive value “A” and a negative value “−A” in synchronization with the zero cross timing of the carrier of the carrier frequency fc. The V-phase voltage command Vv* is a voltage command that keeps a constant positive value “B” without changing with respect to the carrier. The W-phase voltage command Vw* is a voltage command that keeps a constant negative value “−C” without changing with respect to the carrier. In addition, in FIG. 9, A, B, and C have a relationship of A>B=C.

The magnitude relationships are compared between the values of the voltage commands Vu*, Vv*, Vw* and the carrier value. If the value of the carrier is larger, the PWM signal of "Low" is generated. If the carrier value is smaller, a “High” PWM signal is generated. As a result, the illustrated PWM signals UP, VP, WP are generated.

In FIG. 9, since UP=0, VP=0, and WP=0 immediately after starting from the mountain of carriers, V ₀ (000) of the time width T ₁ is output. Next, when the carrier value becomes smaller than the U-phase voltage command Vu*, since UP=1, VP=0, and WP=0, V ₄ (100) having the time width T ₂ is output. Thereafter, similar processing is performed, _V 6 of the time width _{T 3} (110), _V 2 of the time width _{T 4} (010), _V 3 of the time width _{T 5} (011), _V 7 of the time width _{T 6} ( 111) are sequentially output. The time widths T _{1 to} T ₆ can be changed by the values of A, B, and C that are the magnitudes of the voltage commands Vu*, Vv*, and Vw*.

Result of the above processing, the half period Tc / 2 in the first half of the carrier period Tc, as shown in FIGS. 8 and 9, the voltage in the order of _{V 0 → V 4 → V 6} → V 2 → V 3 → V 7 A vector is selected. In the latter half cycle Tc/2 of the carrier cycle Tc, as shown in FIGS. 8 and 9, the voltage vector is selected in the order of V ₇ →V ₃ →V ₂ →V ₆ →V ₄ →V ₀ . In the second cycle of the carrier, the operation of the first cycle is repeated. That is, in the second carrier cycle, the voltage vector is V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V ₇ →V ₇ →V ₃ →V ₂ →V ₆ →V ₄ →V ₀ Selected.

Next, effects obtained by the driving method of the compressor driving device according to the first embodiment will be described with reference to FIGS. 10 and 11. Figure 10 is a diagram schematically showing a state when heated by space vector located in the middle between the voltage vector V ₂ and the voltage vector V _6. FIG. 11: is a figure which shows the mode when heating using the method of Embodiment 1 typically.

When heating is performed by the space vector located between the voltage vector V ₂ and the voltage vector V ₆ , only the switching elements 5b and 5f surrounded by ellipses are energized as shown in FIG. For this reason, the load concentrates on the switching elements 5b and 5f, which are specific switching elements, and the life of the specific switching element is shortened. Further, since heat is concentrated on a specific switching element, there is a problem that the cooling silicone provided between the cooling fins of the module mounting the switching element easily causes a pump-out phenomenon. Further, heat generation of the motor 4 due to copper loss occurs only in the V-phase winding 4V and the W-phase winding 4W indicated by hatching. Therefore, there is a problem that the motor 4 locally generates heat, and it takes time until the heat is uniformized in the compressor.

On the other hand, according to the method of the first embodiment, as shown in FIG. 11, all the switching elements 5a to 5f surrounded by ellipses are energized. Therefore, the load does not concentrate only on the specific switching element. Further, heat generation of the motor 4 due to copper loss occurs in the U-phase winding 4U, the V-phase winding 4V, and the W-phase winding 4W, that is, all windings, which are shown by hatching. Therefore, there is an effect that the heat generation of the motor 4 is made uniform, and the time required until the heat generation is made uniform in the compressor is shortened as compared with the case where only a specific switching element is energized.

If the voltage vector is changed to V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V ₇ , noise and vibration may occur due to the torque generated by the magnetic field generated by the winding. is there. This is because inertia is generated in the motor 4 without rotating the voltage vector once with respect to the space. On the other hand, after changing the voltage vector as V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V ₇ , within the same carrier cycle, V ₇ →V ₃ →V ₂ →V ₆ →V ₄ →V _When it is changed in the direction opposite to ₀ , a new magnetic field acts in the direction of canceling the torque generated in V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V ₇ . Therefore, generation of noise and vibration is suppressed. That is, within one cycle of the carrier, the voltage vector is changed to V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V _7, and then V ₇ →V ₃ →V ₂ →V ₆ →V in reverse order. By changing from ₄ →V ₀ , it becomes possible to heat the motor 4 while suppressing the rotation and vibration of the motor 4.

Further, as described above, the restricted energization includes the DC excitation type restricted energization and the AC excitation type restricted energization. In the case of AC excitation type restraint energization, it is subject to regulation by the Radio Law depending on the carrier frequency or the restraint energizing power. Here, in the method of the first embodiment, as shown in FIG. 8, the voltage vector is changed in a half plane of the 360-degree vector plane, that is, in the 180-degree plane. Therefore, there is no projected component of the voltage vector that reverses the direction of the space vector based on the restricted energization voltage ΣV. Therefore, it can be said that the method of the first embodiment is included in the DC excitation type constraint energization. That is, although the method of the first embodiment includes the ripple component in the motor current, the motor current itself is a direct current and corresponds to the direct-current excitation type restricted energization, so that it is not subject to the regulation by the Radio Law. There is. When the motor current contains a ripple component, a minute pulsation of the rotor may be considered. However, if the optimum carrier frequency is selected for each inductance capacity, weight or mechanical structure of the motor 4, the rotor frequency of the rotor will be reduced. It is possible to suppress pulsation.

It should be noted that it is preferable to change the carrier frequency at regular intervals when performing the restricted energization. By changing the carrier frequency, there is an effect that vibration or noise during restraint energization is suppressed.

At the end of the first embodiment, a hardware configuration for realizing the functions of the above-described first embodiment will be described. FIG. 12 is a block diagram showing an example of a hardware configuration for realizing the function of motor control unit 9 in the first embodiment.

When realizing the function of the motor control unit 9 in the first embodiment, as shown in FIG. 12, a processor 200 that performs an operation, a memory 202 that stores a program read by the processor 200, and signal input/output. It can be configured to include an interface 204 for performing.

The processor 200 may be an arithmetic device such as an arithmetic device, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). Further, the memory 202 is a nonvolatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), a magnetic disk, and a flexible disk. Examples thereof include a disc, an optical disc, a compact disc, a mini disc, and a DVD (Digital Versatile Disc).

The memory 202 stores a program for executing the function of the motor control unit 9 and a table referred to by the processor 200. The processor 200 sends and receives necessary information via the interface 204, the processor 200 executes the program stored in the memory 202, and the processor 200 refers to the table stored in the memory 202 to perform the above-described arithmetic processing. It can be performed. The calculation result by the processor 200 can be stored in the memory 202.

As described above, according to the compressor drive device of the first embodiment, when the compressor needs to be heated, the voltage vector applied to the inverter main circuit is V ₀ →V ₄ within one cycle of the carrier. →V ₆ →V ₂ →V ₃ →V ₇ →V ₇ →V ₃ →V ₂ →V ₆ →V ₄ →V ₀ in order to drive the motor for driving the compressor, the inverter main circuit Concentration of load on a particular switching element in is avoided. This makes it possible to efficiently heat the refrigerant that has accumulated in the compressor.

Embodiment 2.
In the first embodiment, the voltage vector applied to the inverter main circuit 2 is changed to V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V ₇ →V ₇ →V ₃ →V ₂ → within one carrier cycle. Although an example in which the order of change is V ₆ →V ₄ →V ₀ has been shown, another example will be described in the second embodiment. FIG. 13 is a diagram for explaining the method of selecting the voltage vector for heating the refrigerant in the second embodiment. The configuration of the compressor drive device according to the second embodiment is the same as that of the first embodiment.

In FIG. 13, a constraint energization voltage ΣV′ different from that in FIG. 8 is calculated, and a space vector based on the constraint energization voltage ΣV′ is selected. Specifically, four voltage vectors V ₁ , V ₃ , V ₄ , and V ₅ are selected. Thus, in the example of FIG. 13, the four voltage vectors _{V 1, V 3, V 4} , V 5, 2 two zero vector _V 0, _{V 7} six voltage vectors _V 0 was added, _{V1, V} 3, V The output order of ₄ , V ₅ , and V ₇ is determined.

In FIG. 13, if six voltage vectors V ₀ , V ₁ , V ₃ , V ₄ , V ₅ , and V ₇ are selected clockwise, V ₀ →V ₄ →V ₅ →V ₁ →V ₃ → V ₇ is selected in this order. In FIG. 13, if six voltage vectors V ₀ , V ₁ , V ₃ , V ₄ , V ₅ , and V ₇ are selected counterclockwise, V ₇ →V ₃ →V ₁ →V ₅ →V ₄ →V ₀ are selected in this order. Therefore, in the second embodiment, the voltage vector applied to the inverter main circuit 2 is V ₀ →V ₄ →V ₅ →V ₁ →V ₃ →V ₇ →V ₇ →V ₃ →V within one carrier cycle. _The operation changes in the order of ₁ →V ₅ →V ₄ →V ₀ .

If the concepts of the first and second embodiments are combined, four voltage vectors in the 180-degree plane, which is half of the 360-degree vector plane, are selected, and two zeros are added to the selected four voltage vectors. The six voltage vectors to which the vectors are added are sequentially selected according to the vector plane of FIG. Four of the six voltage vectors selected are the first and second voltage vectors, the third voltage vector, and the fourth voltage vector. The first and second voltage vectors are two voltage vectors located on both sides of the space vector representing the restricted energization voltage. The third voltage vector is a voltage vector located adjacent to the opposite side of the space vector with respect to the first voltage vector. The fourth voltage vector is a voltage vector located adjacent to the opposite side of the space vector with respect to the second voltage vector.

In the example of the first embodiment shown in FIG. 8, the first voltage vector corresponds to V ₂ or V ₆ , and the second voltage vector corresponds to V ₆ or V ₂ . Further, the third voltage vector corresponds to V ₃ or V ₄ , and the fourth voltage vector corresponds to V ₄ or V ₃ . Further, in the example of the second embodiment shown in FIG. 13, the first voltage vector corresponds to V ₁ or V ₅ , and the second voltage vector corresponds to V ₅ or V ₁ . Further, the third voltage vector corresponds to V ₃ or V ₄ , and the fourth voltage vector corresponds to V ₄ or V ₃ .

If the zero vector V ₀ is called the first zero vector and the zero vector V ₇ is called the second zero vector, the voltage vector applied to the inverter main circuit 2 in the first and second embodiments is described. Is a first zero vector, a fourth voltage vector, a second voltage vector, a first voltage vector, a third voltage vector, a second zero vector, a second zero vector, a third voltage vector, The order is the first voltage vector, the second voltage vector, the fourth voltage vector, and the first zero vector. Alternatively, the first zero vector, the third voltage vector, the first voltage vector, the second voltage vector, the fourth voltage vector, the second zero vector, the second zero vector, the fourth voltage vector, The order is the second voltage vector, the first voltage vector, the third voltage vector, and the first zero vector.

Embodiment 3.
In the first and second embodiments, the voltage vector applied to the inverter main circuit 2 starts from V ₀ which is the first zero vector and V which is the second zero vector within one cycle of the carrier. _{Although an example in which 7} is sandwiched between and the process ends at V ₀ which is the first zero vector is shown, another example will be described in the third embodiment. FIG. 14 is a diagram for explaining the output order of voltage vectors for heating the refrigerant in the third embodiment. The configuration of the compressor drive device according to the third embodiment is the same as that of the first embodiment.

FIG. 14 shows two left and right views. The diagram on the left is the same as that shown in FIG. Further, in the right diagram, the selection order of the voltage vector is reversed from that in the left side. Here, the selection order shown in the diagram on the left side is called a "first selection order", and the selection order shown in the diagram on the right side is called a "second selection order". Further, a cycle controlled by the first selection order is called a "first cycle", and a cycle controlled by the second selection order is called a "second cycle". Further, the control in the first cycle is called "first control", and the control in the second cycle is called "second control".

The first control is, as described above, the voltage vector in the order of V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V ₇ →V ₇ →V ₃ →V ₂ →V ₆ →V ₄ →V _0. To change. In the second control, the voltage vector changes in the order of V ₇ →V ₃ →V ₂ →V ₆ →V ₄ →V ₀ →V ₀ →V ₄ →V ₆ →V ₂ →V ₃ →V _7. Let In the third embodiment, the first control and the second control are switched at regular intervals. The fixed interval is on the order of tens of seconds to minutes.

Next, effects obtained by the driving method of the compressor driving device according to the third embodiment will be described.

In the DC excitation type restricted energization, if the resistance value component of the motor is small, or in the case of a large-volume compressor, if the busbar voltage or a voltage close to the busbar voltage is applied to the motor, damage to the compressor is assumed. The busbar voltage referred to here is the voltage of the DC power supply 1 in the case of the configuration of FIG.

Therefore, in the DC excitation type restricted energization, the voltage applied to the motor is often much smaller than the bus voltage. As a result, the control for the switching element is a PWM signal with a short on-time and a long off-time, and the inverter loss and heat generation in the inverter main circuit are larger in the regenerative current flowing in the off-time. In the case of the conventional technique, the regenerative current is concentrated in a specific diode, which causes a problem of local heat generation, which causes a shortened life of the diode.

On the other hand, according to the third embodiment, the first control and the second control are switched at regular intervals, so that the regenerative current is supplied to the specific diode during the OFF time of the PWM control. Can be prevented. As a result, it is possible to suppress the concentration of the regenerative current in the specific diode, uniformize the heat generation in the inverter main circuit, and prevent the life of the specific diode from decreasing.

Fourth Embodiment
FIG. 15 is a circuit diagram showing the configuration of the compressor drive device according to the fourth embodiment. In the fourth embodiment shown in FIG. 15, a radiator temperature detector 53 for detecting the temperature of the radiator 56 for cooling the semiconductor element of the inverter main circuit 2 is added to the configuration of the first embodiment shown in FIG. It has been configured. Note that the other configurations are the same as or equivalent to the configurations of the first embodiment shown in FIG. 2, and the same or equivalent components are designated by the same reference numerals and redundant description will be omitted.

An example of the radiator temperature detector 53 is a thermistor, and another example is a thermocouple. The radiator temperature detector 53 may be referred to as a “third temperature detector”. The third temperature Te3, which is the detection value of the radiator temperature detector 53, is output to the inverter control unit 20.

Similarly to the first embodiment, the motor control unit 9 controls the first temperature Te1 which is the detection value of the outside air temperature detector 51 and the first temperature Te which is the detection value of the compressor temperature detector 52 while the compressor 101 is stopped. The stagnation of the refrigerant is detected based on the second temperature Te2. In the fourth embodiment, processing based on the third temperature Te3 which is the detection value of the radiator temperature detector 53 is further added.

The wire bonding for electrically connecting each of the switching elements 5a to 5f of the inverter main circuit 2 and each of the diodes 6a to 6f connected in parallel to each other is subjected to a heat shock a certain number of times or more, so that the bonding is performed. The chances of a face breaking increases. The heat shock referred to here is determined by the temperature environment of the semiconductor such that the semiconductor is cooled to around room temperature when the compressor is stopped after the semiconductor is used in a high load region such as the limit operating temperature of the semiconductor junction. The specifications of the module in which the switching elements 5a to 5f and the diodes 6a to 6f are mounted often describe a power cycle such that a cycle of ΔT[K] is allowed N times. In consideration of this, in the fourth embodiment, processing based on the detected value of the radiator temperature detector 53 is added.

Next, the operation of the compressor drive device according to the fourth embodiment will be described with reference to FIG. FIG. 16 is a flowchart for explaining the operation of the compressor drive device according to the fourth embodiment. The flow of FIG. 16 is executed by the motor control unit 9. The flow of FIG. 16 can be added between step S103 and step S104 in FIG.

In step S201, the third temperature Te3, which is the detected value of the radiator temperature detector 53, is compared with the first set value Tset1, which is the first threshold value. If the third temperature Te3 is higher than the first set value Tset1 (step S201, No), it is determined that the module temperature is higher than the power cycle allowable value, and the flow of FIG. Get out.

On the other hand, when the third temperature Te3 is equal to or lower than the first set value Tset1 (step S201, Yes), the process proceeds to step S202. In step S202, the third temperature Te3 is compared with the second set value Tset2 which is the second threshold value. The second set value Tset2 is lower than the first set value Tset1. When the third temperature Te3 is equal to or lower than the second set value Tset2 (Yes in step S202), the process proceeds to step S203. In step S203, it is determined that the module temperature is lower than the power cycle allowable value, and the restricted energization is performed normally. After the restraint energization has been carried out, the flow of FIG. 16 is exited.

On the other hand, when the third temperature Te3 is higher than the second set value Tset2 (No in step S202), the process proceeds to step S204. In step S204, restricted energization is performed with the energization time limited. The process of step S204 is a process that considers both the possibility that the refrigerant will fall asleep and the heat shock to the module. By the process of step S204, the temperature of the element in the module is controlled to fall within a certain temperature range. As a result, it is possible to protect the elements in the module while preventing the refrigerant from stagnation.

Embodiment 5.
In the fifth embodiment, materials for forming the switching elements 5a to 5f and the diodes 6a to 6f of the inverter main circuit 2 will be described. Although silicon (Si) is generally used as a material for forming the switching elements 5a to 5f and the diodes 6a to 6f, silicon carbide (SiC), which has been attracting attention in recent years, may be used.

The SiC element made of silicon carbide has excellent heat transfer coefficient and can operate at high temperature as compared with the Si element made of silicon. By using the SiC element for the switching elements 5a to 5f and the diodes 6a to 6f, the benefit of the SiC element can be obtained. That is, since the SiC element can operate at a high temperature, it is possible to increase the energization amount during the constraint energization. As a result, it becomes possible to efficiently carry out the restricted energization.

The SiC element is an example of a semiconductor called a wide bandgap semiconductor in view of the characteristic that the bandgap is larger than that of the Si element. In addition to this SiC element, a semiconductor formed using, for example, a gallium nitride-based material or diamond belongs to the wide band gap semiconductor, and their characteristics are similar to that of SiC in many cases. Therefore, configurations using wide band gap semiconductors other than SiC also form the subject of the present invention.

In addition, since a switching element formed of such a wide band gap semiconductor has high withstand voltage and high allowable current density, the switching element can be downsized, and the downsized switching element should be used. As a result, it is possible to downsize the power module equipped with these elements.

Note that the configurations described in the above embodiments are examples of the content of the present invention, and can be combined with other known techniques, and the configurations are within the scope not departing from the gist of the present invention. It is also possible to omit, change or add a part of. For example, a winding temperature detector that detects the temperature of the winding of the motor 4 may be provided. The resistance value of the winding of the motor 4 changes depending on the temperature of the winding and the current flowing through the winding. Therefore, if the detected value of the winding temperature detector is used in addition to the current Idc which is the detected value of the current detector 8 and the second temperature Te2 which is the detected value of the compressor temperature detector 52, the phase of the motor 4 is reduced. The resistance value can be determined. If the phase resistance value of the motor 4 can be determined, even if the phase resistance value changes, it is possible to stably supply the electric power for the constraint energization.

1 DC power supply, 2 inverter main circuit, 4 motor, 4U U phase winding, 4V V phase winding, 4W W phase winding, 5a-5f switching element, 6a-6f diode, 7 DC voltage detector, 8 current detection Device, 9 motor control unit, 10 PWM control unit, 11 current restoration unit, 12 coordinate conversion unit, 13 estimation unit, 14 speed control unit, 15 current control unit, 16 voltage command calculation unit, 17 carrier generation unit, 18 carrier comparison Section, 20 inverter control section, 30 compressor drive device, 51 outside air temperature detector, 52 compressor temperature detector, 53 radiator temperature detector, 56 radiator, 100 heat pump device, 101 compressor, 102 four-way valve, 103 , 104 heat exchanger, 105 expansion mechanism, 106 refrigerant piping, 107 compression mechanism, 200 processor, 202 memory, 204 interface.

Claims (10)

A compressor drive device that performs restraint energization control for heating a drive motor of a compressor,
An inverter main circuit that converts direct current to alternating current and applies alternating voltage to the drive motor,
A DC voltage detector for detecting a DC voltage applied to the inverter main circuit,
A current detector for detecting a current flowing through the inverter main circuit,
A first temperature detector for detecting the outside air temperature,
A second temperature detector for detecting the temperature of the compressor,
An inverter control unit that PWM-controls a switching element of the inverter main circuit based on a detection value of the DC voltage detector, a detection value of the current detector, and a carrier;
Equipped with
The inverter control unit determines the binding energization voltage based on the detection value of the DC voltage detector, the detection value of the first temperature detector, and the detection value of the second temperature detector, and the determined A space vector in the space vector modulation method is calculated based on the restricted energization voltage, and the first and second voltage vectors that are two voltage vectors located on both sides of the calculated space vector and the first voltage vector are A third voltage vector located adjacent to the opposite side of the space vector with respect to the reference, and a fourth voltage vector located adjacent to the opposite side of the space vector with respect to the second voltage vector, The six voltage vectors obtained by adding the first and second zero vectors, which are two zero vectors, to the selected first, second, third and fourth voltage vectors are set to one cycle of the carrier. In which the first zero vector, the fourth voltage vector, the second voltage vector, the first voltage vector, the third voltage vector, the second zero vector, the second zero. A vector, the third voltage vector, the first voltage vector, the second voltage vector, the fourth voltage vector, and the first zero vector are output to the inverter main circuit in this order. And compressor drive device. The inverter control unit,
The first zero vector, the fourth voltage vector, the second voltage vector, the first voltage vector, the third voltage vector, the second zero vector, the second zero vector, the A third voltage vector, the first voltage vector, the second voltage vector, the fourth voltage vector, and the first control to output to the inverter main circuit in the order of the first zero vector, The second zero vector, the third voltage vector, the first voltage vector, the second voltage vector, the fourth voltage vector, the first zero vector, the first zero vector, the A fourth voltage vector, the second voltage vector, the first voltage vector, the third voltage vector, and the second control to output to the inverter main circuit in the order of the second zero vector, Equipped with,
The compressor drive device according to claim 1, wherein the first control and the second control are switched at regular intervals. The compressor drive device according to claim 1 or 2, wherein the inverter control unit changes the frequency of the carrier at a constant cycle or randomly during execution of the restricted energization control. A third temperature detector for detecting the temperature of the radiator for cooling the semiconductor switching element of the inverter main circuit,
The inverter control unit determines whether or not to perform the restraint energization control, based on a comparison result between a detection value of the third temperature detector and a first threshold value. The compressor drive device according to claim 1. The inverter control unit, when the detection value of the third temperature detector is less than or equal to the first threshold value, further the detection value of the third temperature detector, a second smaller than the first threshold value. Comparing with a threshold value, based on the comparison result of the detection value of the third temperature detector and the second threshold value, it is determined whether or not to perform the restraint energization control of controlling the energization time. Item 4. The compressor drive device according to Item 4. The compressor drive device according to any one of claims 1 to 5, wherein the switching element of the inverter main circuit is formed of a wide band gap semiconductor. The compressor drive device according to claim 6, wherein the wide band gap semiconductor is silicon carbide, gallium nitride, or diamond. A heat pump device comprising the compressor drive device according to any one of claims 1 to 7. An air conditioner comprising the heat pump device according to claim 8. A refrigerator comprising the heat pump device according to claim 8.

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