WO2014155622A1

WO2014155622A1 - Heat pump device, air conditioner, and freezer

Info

Publication number: WO2014155622A1
Application number: PCT/JP2013/059350
Authority: WO
Inventors: 庄太神谷; 和徳畠山; 勝之天野; 典和伊藤; 雅史冨田
Original assignee: 三菱電機株式会社
Priority date: 2013-03-28
Filing date: 2013-03-28
Publication date: 2014-10-02
Also published as: JP6480859B2; JPWO2014155622A1

Abstract

In order to provide a heap pump device that suppresses cost increases and is capable of sensorless vector control by accurately detecting current even at low rotational speeds (low rotational frequency) or with low loads, this heat pump device comprises a detection circuit with filter functionality (17) that includes a filter circuit and a detection circuit and that removes harmonic noise, and a rotational frequency and load calculating unit (16) switches between the filter circuit and the detection circuit of the detection circuit with filter functionality (17) according to whether the rotational frequency or the load for a motor (8) is less than or equal to a set value, and corrects the phase difference of the output signal of the detection circuit with filter functionality (17) when the rotational frequency or the load for the motor (8) is less than or equal to the set value.

Description

Heat pump device, air conditioner and refrigerator

The present invention relates to a heat pump device, an air conditioner, and a refrigerator using a compressor.

In a compressor of a conventional heat pump device, vector control is generally used when controlling the magnetic pole position of a permanent magnet synchronous motor provided in the compressor without a sensor. In the vector control, the motor current is separated into a d-axis component and a q-axis component, and an optimal current value corresponding to the position of the rotor is calculated, so that highly efficient control with little torque fluctuation can be performed.

In order to perform such vector control, it is necessary to grasp the magnetic pole position of the rotor. In high-speed sensorless vector control that does not use a magnetic pole position sensor, the magnetic pole position is estimated from the current (motor current) value flowing through the motor. That is, the motor current is detected by a current sensor, and the detected current is separated into an excitation current (d-axis current I _d ) and a torque current (q-axis current I _q ) to estimate the magnetic pole position.

In actual vector control, a dc-qc rotational coordinate system having an estimated angle θdc in the control system is assumed with respect to a dq rotational coordinate system in which the magnetic pole position of the rotor is a rotational position of the actual angle θd. The axis error Δθ is estimated and calculated. Then, the voltage command value of the inverter is feedback-corrected so that the axis error Δθ is zero, thereby controlling the actual magnetic pole position to coincide with the control magnetic pole position.

According to such vector control, the magnitude and phase of the current that drives the motor are ideally controlled by the inverter according to the motor rotation speed (number of rotations) or the load level, resulting in high torque, high response, and high Performance and high precision can be controlled. However, sensorless vector control cannot be used during startup when the current flowing through the motor cannot be used. Therefore, a method of switching the control method between a section from start to low speed operation and a section exceeding low speed operation has been studied. For example, in Patent Document 1, V / F constant control that does not require magnetic pole position detection is performed during low-speed operation from startup, and is set in advance when high-speed operation exceeds a predetermined rotation speed (number of rotations) or load. A technique for shifting to vector control using the initial magnetic pole position is disclosed.

JP 2004-48886 A

When the motor is operated at a low rotational speed (small rotational speed) or in a low load state, the motor current (the sum of the torque current component and the field current component) is also reduced. Therefore, the magnetomotive force of the output of the current sensor that detects the motor current is weakened, the output waveform is distorted, or the phase of the detected motor current is advanced with respect to the phase of the actual current. Also in a detection circuit that detects a signal from a current sensor, a detection error due to a component difference or the like increases due to a small detection current. If these output waveforms input to the microcomputer are distorted with respect to the actual output waveform and the phase advances, estimation of the magnetic pole position will fail, causing step-out and forcibly stopping the motor.

In order to obtain a sufficient magnetomotive force even when the motor current is small, the number of turns of the transformer may be increased, but the cost will increase. Therefore, according to the conventional technique, it is difficult to satisfactorily perform sensorless vector control at a low speed (or low load) while suppressing an increase in cost.

According to the technique disclosed in Patent Document 1, V / F constant control and vector control can be used properly, but the motor is operated at a low rotational speed (small rotational speed) or is in a low load state. It is difficult to perform sensorless vector control.

The present invention has been made in view of the above, and is capable of performing sensorless vector control by performing accurate current detection even at a low rotation speed (small rotation speed) or a low load while suppressing an increase in cost. The object is to obtain a possible heat pump device.

In order to solve the above-described problems and achieve the object, the heat pump device of the present invention is driven by a motor and compresses a refrigerant, an inverter for applying a voltage to the motor, and a current flowing through the motor. A current sensor including two secondary resistances having different resistance values, and an inverter control unit that outputs a drive signal to the inverter unit, wherein the inverter control unit detects a current detected by the current sensor. A voltage detection unit that calculates a voltage command value based on a signal from the current detection unit, a drive signal generation unit that generates the drive signal based on the voltage command value, A rotation number and a load for calculating a rotation number and a load of the motor, and the drive signal generation unit determines a necessary refrigerant compression amount of the compressor based on a signal from the current sensor An amplitude phase determination unit that determines an amplitude and phase from the necessary refrigerant compression amount and causes the drive signal generation unit to generate the drive signal, the current detection unit including a filter circuit and a detection circuit, and harmonic noise And a detection circuit with a filter function, and the rotation speed and load calculation unit determines whether the rotation speed or load of the motor is equal to or less than a set value. The filter circuit and the detection circuit of the detection circuit with function are switched, and when the rotation speed or load of the motor is not more than a set value, the phase difference of the output signal of the detection circuit with filter function is corrected.

According to the present invention, there is provided a compressor equipped with a motor capable of sensorless vector control by performing accurate current detection even at a low rotation speed (small rotation speed) or a low load while suppressing an increase in cost. There is an effect that a heat pump device can be obtained.

FIG. 1 is a diagram illustrating a configuration example of a heat pump device according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of an inverter unit, an inverter control unit, and a compressor that form part of the heat pump device according to the first embodiment. FIG. 3 is a comparison diagram showing the relationship between the motor current waveform and the output waveform of the current sensor (ACCT) when the motor according to the first embodiment has a low rotation speed (small rotation speed) or a low load. FIG. 4 is a diagram illustrating a motor current waveform and a detection circuit output waveform when the detection circuit resistance value is 1 kΩ according to the first embodiment. FIG. 5 is a diagram illustrating a motor current waveform and a detection circuit output waveform when the detection circuit resistance value is 10Ω, according to the first embodiment. FIG. 6 is a flowchart for explaining the operation of the rotation speed and load calculation unit according to the first embodiment. FIG. 7 is a diagram illustrating a configuration example of the current sensor and the peripheral circuit according to the first embodiment. FIG. 8 is a diagram showing the relationship between the breakdown voltage and the on-resistance of the Si device and the SiC device according to the second embodiment. FIG. 9-1 is a diagram illustrating a configuration example of a device including the heat pump device according to Embodiment 3 during heating operation. FIG. 9-2 is a diagram illustrating a configuration example of a device including the heat pump device according to the third embodiment during the cooling operation. FIG. 10 is a Mollier diagram of the refrigerant of the heat pump apparatus shown in FIGS. 9-1 and 9-2 according to the third embodiment.

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

Embodiment 1 FIG.
In the present embodiment, the configuration and operation of the heat pump device of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing a heat pump device 100 which is a configuration example of the heat pump device of the present embodiment. A heat pump device 100 shown in FIG. 1 includes a refrigeration cycle unit 20, an inverter unit 9, and an inverter control unit 10. The heat pump device 100 is applied to, for example, an air conditioner or a refrigerator.

The refrigeration cycle unit 20 includes a compressor 1, a four-way valve 2, a heat exchanger 3, an expansion mechanism 4, and a heat exchanger 5, which are connected via a refrigerant pipe 6.

The compressor 1 includes a compression mechanism 7 and a motor 8 inside. The compression mechanism 7 compresses the refrigerant. The motor 8 is a three-phase motor having three-phase windings of U phase, V phase, and W phase, and operates the compression mechanism 7.

The inverter unit 9 connected to the DC power (bus voltage Vdc) as a power source includes

current sensors

26a and 26b. In addition, the power supply connected to the inverter part 9 should just be a thing which can supply direct-current power, and is not limited to a specific thing. Examples of the power source connected to the inverter unit 9 include a solar cell and an AC power source to which a rectifier is added.

The inverter control unit 10 includes a refrigerant compression operation mode control unit 11 and a drive signal generation unit 14. The refrigerant compression operation mode control unit 11 includes a d-axis and q-axis current detection unit 12, a voltage command calculation unit 13, and a rotation speed and load calculation unit 16. The drive signal generation unit 14 includes an amplitude phase determination unit 15 and a PWM signal generation unit 24.

The inverter unit 9 supplies AC power to the electrically connected motor 8 to drive the motor 8.

The inverter unit 9 applies the U-phase voltage Vu, the V-phase voltage Vv, and the W-phase voltage Vw to the U-phase, V-phase, and W-phase windings of the motor 8, respectively.

Current sensors

26a and 26b provided in the inverter unit 9 detect a current (motor current) flowing through the motor 8 in order to estimate the magnetic pole position. The currents (signals) detected by the

current sensors

26 a and 26 b are output to the d-axis and q-axis current detection unit 12.

The inverter control unit 10 generates an inverter drive signal (for example, a PWM (Pulse Width Modulation) signal) from the necessary refrigerant compression amount of the compressor 1 and outputs it to the electrically connected inverter unit 9.

The refrigerant compression operation mode control unit 11 controls the refrigerant compression operation of the heat pump device 100. The refrigerant compression operation mode control unit 11 controls the drive signal generation unit 14 to output an inverter drive signal (for example, a PWM signal) for driving the motor 8 from the inverter control unit 10. At this time, the voltage command calculation unit 13 determines the magnetic pole position of the motor 8 based on the d-axis current signal (I _d ) and the q-axis current signal (I _q ) output from the d-axis and q-axis current detection unit 12. And a control signal is output to the drive signal generator 14. The d-axis current signal (I _d ) and the q-axis current signal (I _q ) are based on the motor current of the motor 8 detected by the current sensors 26 a and 26 _b of the inverter unit 9. The drive signal generation unit 14 generates and outputs a signal (for example, a PWM signal) for driving the inverter unit 9 based on the control signal output from the voltage command calculation unit 13.

FIG. 2 is a diagram illustrating a configuration example of the compressor 1, the inverter unit 9, and the inverter control unit 10 included in the heat pump device 100.

The inverter unit 9 includes six switching elements 27a to 27f, and three series connection units including two switching elements are connected in parallel. Each of the switching elements 27a to 27f is provided with a diode element. The inverter unit 9 drives the switching elements corresponding to the PWM signals (UP, UN, VP, VN, WP, WN) as drive signals input from the inverter control unit 10 to thereby drive the three-phase voltage Vu. , Vv, and Vw are generated, and voltages corresponding to the U-phase, V-phase, and W-phase windings of the motor 8 are applied.

The d-axis and q-axis current detection unit 12 includes a detection circuit 17 with a filter function, a phase current calculation unit 18, and a three-phase two-phase conversion unit 19.

The detection circuit 17 with a filter function removes harmonic noise from the signal output by the

current sensors

26a and 26b detecting the motor current. The detection circuit 17 with a filter function may be an analog filter or a digital filter.

The phase current calculation unit 18 uses the U-phase current I _U , V-phase current I _V, and W based on the signals from the

current sensors

26 a and 26 b (the signals from which harmonic noise has been removed by the detection circuit 17 with a filter function). The phase current _IW is calculated and output to the three-phase / two-phase converter 19. Here, the signal obtained by the phase current calculation unit 18 from the

current sensors

26a and 26b may be at least for two phases. This is because the phase current calculation unit 18 can calculate the current values of the remaining phases by utilizing the fact that the phase of each phase current is shifted by 120 °.

The three-phase to two-phase converter 19 converts the U-phase current I _U , V-phase current I _V and W-phase current I _W obtained by the phase current calculator 18 into an excitation current (d-axis current I _d ) and a torque current ( The coordinate is converted to q-axis current I _q ) and output to voltage command calculation unit 13.

The rotation speed and load calculation unit 16 includes a detection circuit switching unit 30 with a filter function and a secondary resistance switching unit 31.

The detection circuit switching unit 30 with a filter function switches the filter circuit according to the rotational speed (the number of rotations) of the motor 8 or the load level. The secondary side resistance switching unit 31 switches the detection circuit (secondary side resistance) in the

current sensors

26a and 26b according to the rotational speed (the number of rotations) of the motor 8 or the load level. The rotation speed and load calculation unit 16 preferably has a storage area, and the storage area includes a filter circuit and a detection circuit to be selected corresponding to the rotation speed (rotation speed) of the motor 8 or the load level. The correction signal value corresponding to the resistance value of the secondary resistance may be stored as table data (table 16a). Here, the value stored as the table 16a is a value measured in advance.

The drive signal generation unit 14 includes a two-phase / three-phase conversion unit 25.

The two-phase / three-phase conversion unit 25 converts the two-phase signal from the voltage command calculation unit 13 into a three-phase signal and outputs the three-phase signal to the PWM signal generation unit 24. That is, the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* are converted into a U-phase voltage command value Vu ^* , a V-phase voltage command value Vv ^*, and a W-phase voltage command value Vw ^* to generate a PWM signal generator. 24.

The PWM signal generation unit 24 generates a PWM signal for driving the inverter unit 9 based on the three-phase voltage command value from the two-phase / three-phase conversion unit 25. The inverter unit 9 drives the motor 8 based on the PWM signal generated and output by the PWM signal generation unit 24.

Incidentally, it has been confirmed that when the motor 8 has a low rotation speed (small rotation speed) or a low load, the output waveform of an ACCT (Alternating Current Current Transducer) that is a current sensor is distorted.

4 and 5 show detection waveforms of the detection circuit (ACCT) when the motor 8 is at a low rotation speed (small rotation speed) or a low load. FIG. 4 shows an amplifier output waveform 40 when the secondary resistance is 1 kΩ, an actual current waveform 41, and an ACCT output waveform 42, and FIG. 5 shows an amplifier when the secondary resistance is 10Ω. An output waveform 40a, an actual current waveform 41a, and an ACCT output waveform 42a are shown.

In FIG. 4, since the secondary resistance value is as large as 1 kΩ, the current is saturated in the ACCT, and the ACCT output waveform 42 is distorted with respect to the actual current waveform 41. In FIG. 4, the phase difference between the actual current waveform 41 and the ACCT output waveform 42 is about 5.0 ms (54.2 deg). An error occurs in the estimation of the magnetic pole position of the motor 8 due to the current fluctuation caused by this phase difference.

On the other hand, in FIG. 5, since the secondary resistance value is an appropriate value of 10Ω, the current does not saturate in the ACCT, and the ACCT output waveform 42a and the actual current waveform 40a substantially coincide with each other. The phase difference of the ACCT output waveform 42a is reduced to about 1.2 ms (13.0 deg). As described above, when the secondary resistance value is set to an appropriate value, the phase difference is compensated, and the magnetic pole position of the motor 8 can be accurately estimated.

Therefore, in the heat pump device according to the present embodiment, the rotation speed and load calculation unit 16 switches the filter circuit and the detection circuit so that the magnetic pole position of the motor 8 can be accurately estimated. Here, the switching timing of the filter circuit and the detection circuit is determined with reference to the rotation speed and the table 16 a provided in the load calculation unit 16. The values in the table 16a are values measured in advance.

Next, the operation of the rotation speed and load calculation unit 16 will be described with reference to FIG. FIG. 6 is a flowchart for explaining the operation of the rotation speed and load calculation unit 16.

First, when the operation is started, it is determined whether or not the rotation speed (number of rotations or frequency) of the motor 8 is equal to or less than a set value, or whether or not the load of the motor 8 is equal to or less than the set value (S1). When the rotational speed (number of rotations) or load of the motor 8 is less than or equal to the set value, the switching control is performed (S2), and then the sensorless vector control is performed (S3). Without performing the sensorless vector control (S3).

After performing the sensorless vector control in this way, it is determined again whether or not the rotational speed (the number of rotations) of the motor 8 is less than or equal to the set value, or whether or not the load on the motor 8 is less than or equal to the set value. Return to step (S1).

Further, when the filter circuit and the detection circuit are switched when the rotation speed (the number of rotations) or the load of the motor 8 is equal to or less than the set value, the motor 8 is operated at a low rotation speed (the small number of rotations) or the motor 8 Even when the motor is operated at a low load, each current sensor can accurately detect the current flowing through the motor 8 without using a high-turn current sensor for the

current sensors

26a and 26b. That is, the current flowing through the motor 8 can be accurately detected while suppressing an increase in cost, and the magnetic pole position of the motor 8 can be accurately estimated. Therefore, it is possible to prevent or suppress the step-out phenomenon due to the failure or deviation of the magnetic pole position detection.

As described above, according to the present invention, the motor 8 can be driven without problems at a lower rotational speed (number of rotations) or lower load than before, and the power consumption of the heat pump apparatus 100 can be reduced.

Here, the

current sensors

26a and 26b included in the heat pump device of the present invention will be described with reference to FIG.

FIG. 7 is a diagram illustrating a configuration example of the current sensor and its peripheral circuits. In the configuration shown in FIG. 7, the

current sensors

26 a and 26 b include a detection circuit, and a signal output through the detection circuit is input to the microcomputer 45 through the filter circuit. The

current sensors

26a and 26b shown in FIG. 7 have a secondary resistance of ACCT that is a low resistance resistance element 43a (for example, 10Ω) included in the

current sensors

26a and 26b or a high resistance included in the detection circuit 17 with a filter function. The resistance element 43b (eg, 1 kΩ) can be switched. The microcomputer 45 corresponds to the phase current calculation unit 18 in FIG.

When the resistance value of the secondary side resistance of the ACCT is low (Ra), the output voltage becomes low, so the amplifier 44 is provided in the secondary output stage. This is because the voltage input to the microcomputer 45 is amplified to a voltage that can be input. In addition, although the operational amplifier is illustrated in FIG. 7 as the amplifier 44, it is not limited to this.

When the resistance value of the secondary resistance is high (Rb), a voltage that can be input to the microcomputer 45 is output, so that a sufficiently high voltage that can be input to the microcomputer 45 can be output without using the amplifier 44.

Here, the magnetomotive force NI is expressed as NI = Rmφ using the magnetic resistance Rm and the magnetic flux φ. If the resistance value of the secondary resistance is high, the magnetomotive force is high and magnetic saturation occurs when the same magnetic flux (current) is applied to the ACCT, and the output waveform is distorted.

FIG. 3 is a diagram showing a relationship between the motor current waveform 34 (sinusoidal actual current waveform) and the output waveform 35 of the ACCT when the motor 8 is at a low rotation speed (small rotation speed) or a low load. In FIG. 3, the motor current waveform 34 is indicated by a solid line, and the output waveform 35 of the ACCT is indicated by a broken line.

In the configuration example shown in FIG. 7, when the resistance value of the secondary resistance is high (Rb), the magnetomotive force NI in a constant magnetic flux (constant current) becomes high, and magnetic saturation occurs. When magnetic saturation occurs, the output waveform is distorted and a phase error occurs.

Therefore, in the configuration example shown in FIG. 7, the detection circuit with the filter function is switched by the rotation speed and load calculation unit 16. For the signal used for switching, a value corresponding to the rotation speed (number of rotations) or load when the resistance element 43b having a high resistance value is applied is acquired in advance and stored as table data. Please refer to this. The configuration of the storage area for storing the switching signal is not particularly limited. For example, if a storage area is provided in the refrigerant compression operation mode control unit 11 and values used for switching are stored as table data in the storage area. Good. Here, the value used for the switching control is determined by the rotation speed and the load.

When magnetic saturation occurs, harmonic components are superimposed due to waveform distortion. Therefore, in the configuration example of FIG. 7, a filter circuit including a resistor element and a capacitor element is provided after the secondary output of the ACCT, and the filter circuit can reduce or remove harmonic components. .

Note that the filter circuit may not be provided. If the filter circuit is not provided, after the current value is taken into the microcomputer 45, the harmonic component may be reduced or removed by averaging with reference to the previous value.

7 adopts the optimum filter circuit and detection circuit according to the rotation speed and load, and solves the problem of waveform distortion at low load and low rotation speed. As a result, even in a low rotational speed range, the motor 8 can be driven more stably by performing highly accurate current detection while suppressing an increase in cost due to an increase in the number of turns of the ACCT.

As described above, the heat pump device 100 according to the present embodiment includes the filter circuit and the detection circuit, includes the detection circuit 17 with the filter function that removes harmonic noise, and the rotation speed and load calculation unit 16 includes the motor 8. When the filter circuit and the detection circuit of the detection circuit with filter function 17 are switched according to whether the rotation speed or load of the motor 8 is equal to or less than a set value, and the rotation speed or load of the motor 8 is equal to or less than the set value In this case, the phase difference of the output signal of the detection circuit 17 with a filter function is corrected.

Embodiment 2. FIG.
In the present embodiment, a preferred embodiment of the heat pump device 100 of the present invention will be described. In the present embodiment, wide band gap semiconductors are used for the switching elements 27a to 27f (FIG. 2) provided in the heat pump apparatus 100.

By using wide band gap semiconductors for the switching elements 27a to 27f, it is possible to reduce the element loss in the switching elements 27a to 27f and increase the current. Therefore, it is possible to downsize or remove the radiation fins compared to the case where no wide band gap semiconductor is used.

Note that examples of the wide band gap semiconductor that can be used in this embodiment include silicon carbide (also referred to as silicon carbide or SiC), diamond, or a gallium nitride-based material (a material containing gallium nitride as a main component). be able to.

FIG. 8 is a diagram showing the relationship between the breakdown voltage and the on-resistance of the silicon device (Si device) and the silicon carbide device (SiC device). Between the breakdown voltage and the on-resistance, there is a trade-off relationship in which the on-resistance increases as the breakdown voltage increases and the breakdown voltage decreases as the on-resistance decreases. However, since the band gap of the SiC device is larger than the band gap of the Si device, the breakdown voltage of the SiC device is much higher than the breakdown voltage of the Si device when compared at an arbitrary on-resistance value (see FIG. 8). . Therefore, by using the SiC device, the trade-off between the breakdown voltage and the on-resistance can be greatly improved. For example, a current induction heating cooker using a Si device requires a cooling device or a heat radiating fin, but the element loss can be greatly reduced by using a SiC device. It is possible to reduce the size of the heat dissipating fins or to remove them. Therefore, the cost of the device itself can be greatly reduced.

Further, since wide band gap semiconductors are used for the switching elements 27a to 27f, switching at a high frequency is possible, so that a higher frequency current can be supplied to the motor 8. Therefore, the current flowing into the inverter unit 9 can be reduced by reducing the winding current due to the increase in the winding impedance of the motor 8, and a more efficient heat pump device can be obtained.

As described in the first embodiment, the heat pump device according to the present invention can operate stably even during low-speed operation by correction control by the switching unit. In the case of a load, if a large amount of current flows, the element loss increases, resulting in high temperature operation.

However, by using a wide bandgap semiconductor, particularly an SiC device, as the switching element, a large amount of current can flow while suppressing element loss as compared with the case of using a conventional Si device. Therefore, the temperature rise can be suppressed, and the cooling device or the heat radiation fin can be downsized or deleted.

Examples of the configuration of the switching elements 27a to 27f include an IGBT (Insulated Gate Bipolar Transistor), a power MOSFET having a super junction structure, and the like, but are not limited thereto, and other insulated gate semiconductor elements or bipolar transistors May be used.

Note that only the diodes of the switching elements 27a to 27f provided in the inverter unit 9 may be wide band gap semiconductors. Further, a wide band gap semiconductor may be used for only a part (at least one) of the switching elements provided in the switching elements 27a to 27f. The above effect can also be obtained when a wide bandgap semiconductor is applied to only some elements.

Embodiment 3 FIG.
In this embodiment, a device (such as an air conditioner or a refrigerator) to which the heat pump device 100 described in

Embodiments

1 and 2 is applied will be described.

FIGS. 9-1 and 9-2 are diagrams illustrating a configuration example of a device including the heat pump device 100. FIG. FIG. 9-1 shows a configuration example during heating operation, and FIG. 9-2 shows a configuration example during cooling operation. Note that the refrigerant circulation direction is different between FIGS. 9-1 and 9-2, and this switching is performed by a four-way valve 57 described later. FIG. 10 is a diagram illustrating a Mollier diagram regarding the state of the refrigerant in the heat pump apparatus 100 illustrated in FIGS. 9-1 and 9-2. In FIG. 10, the horizontal axis is the specific enthalpy h, and the vertical axis is the refrigerant pressure P.

The compressor 49, the heat exchanger 50, the expansion mechanism 51, the receiver 52, the internal heat exchanger 53, the expansion mechanism 54, and the heat exchanger 55 are connected to each other by a pipe, and a main refrigerant circuit in which the refrigerant circulates through the pipe. Is configured. The main refrigerant circuit is divided into main refrigerant circuits 56a to 56k in FIGS. 9-1 and 9-2, respectively. A four-way valve 57 is provided on the discharge side of the compressor 49, and the refrigerant circulation direction can be switched. A fan 58 is provided in the vicinity of the heat exchanger 55.

The compressor 49 corresponds to the compressor 1 in the first and second embodiments (see FIG. 1), and includes a motor 8 and a compression mechanism 7 driven by the inverter unit 9. Furthermore, the heat pump device 100 is provided with injection circuits 60a to 60c (shown by bold lines) that connect between the receiver 52 and the internal heat exchanger 53 to the injection pipe of the compressor 49. An expansion mechanism 59 and an internal heat exchanger 53 are connected to the injection circuits 60a to 60c.

A water circuit (represented by a thick line) composed of a water circuit 61a and a water circuit 61b is connected to the heat exchanger 50, and water is circulated. The water circuit 61a and the water circuit 61b are connected to a device that uses water, such as a radiator provided in a water heater, a radiator, or floor heating.

Next, the operation of the heat pump apparatus 100 will be described. First, the operation when the heat pump device 100 performs a heating operation (when operated as a water heater) will be described with reference to FIG.

First, the refrigerant in the gas phase is compressed by the compressor 49 to be in a high temperature and high pressure state (point A in FIG. 10).

The high-temperature and high-pressure refrigerant is discharged from the compressor 49 to the main refrigerant circuit 56a. The refrigerant in the main refrigerant circuit 56 a is transferred to the four-way valve 57, and the refrigerant in the main refrigerant circuit 56 b that passes through the four-way valve 57 is transferred to the heat exchanger 50. The transferred refrigerant in the main refrigerant circuit 56b is cooled and liquefied by heat exchange in the heat exchanger 50 (point B in FIG. 10). That is, the heat exchanger 50 is a condenser and functions as a radiator in the main refrigerant circuit. At this time, the water in the water circuit 61a is warmed by the heat radiated from the refrigerant in the main refrigerant circuit. The water in the heated water circuit 61b is used for heating or hot water supply.

The refrigerant in the main refrigerant circuit 56c liquefied by the heat exchanger 50 is transferred to the expansion mechanism 51, and is decompressed by the expansion mechanism 51 to be in a gas-liquid two-phase state (point C in FIG. 10).

The refrigerant in the main refrigerant circuit 56d in the gas-liquid two-phase state is transferred to the receiver 52, transferred to the compressor 49 by the receiver 52 (refrigerant transferred from the main refrigerant circuit 56j to the main refrigerant circuit 56k), and heat. It is exchanged, cooled and liquefied (point D in FIG. 10).

The refrigerant in the main refrigerant circuit 56e liquefied by the receiver 52 branches to the main refrigerant circuit 56f and the injection circuit 60a at a point P in FIG. The refrigerant flowing from the main refrigerant circuit 56f to the internal heat exchanger 53 is further cooled in the internal heat exchanger 53 by heat exchange with the refrigerant transferred from the injection circuit 60b to the injection circuit 60c (point E in FIG. 10). The refrigerant flowing through the injection circuit 60b is decompressed by the expansion mechanism 59 and is in a gas-liquid two-phase state.

The refrigerant in the main refrigerant circuit 56g cooled by the internal heat exchanger 53 is transferred to the expansion mechanism 54 and depressurized to be in a gas-liquid two-phase state (point F in FIG. 10).

The refrigerant in the main refrigerant circuit 56h, which has been in the gas-liquid two-phase state by the expansion mechanism 54, is transferred to the heat exchanger 55, exchanged with the outside air in the heat exchanger 55, and heated (point G in FIG. 10). That is, the heat exchanger 55 functions as an evaporator in the main refrigerant circuit.

The refrigerant in the main refrigerant circuit 56 i heated by the heat exchanger 55 is transferred to the four-way valve 57, and the refrigerant in the main refrigerant circuit 56 j passing through the four-way valve 57 is transferred to the receiver 52 and further received by the receiver 52. Heated (point H in FIG. 10), the heated refrigerant in the main refrigerant circuit 56k is transferred to the compressor 49.

On the other hand, the refrigerant in the injection circuit 60a branched at the point P (injection refrigerant (point D in FIG. 10)) is decompressed by the expansion mechanism 59 (point I in FIG. 10), and the decompressed refrigerant in the injection circuit 60b is Heat exchange is performed by the internal heat exchanger 53, and a gas-liquid two-phase state is obtained (point J in FIG. 10). The refrigerant in the injection circuit 60 c heat-exchanged by the internal heat exchanger 53 is transferred from the injection pipe of the compressor 49 into the compressor 49.

In the compressor 49, the refrigerant (point H in FIG. 10) from the main refrigerant circuit 56k is compressed to an intermediate pressure and heated (point K in FIG. 10). The refrigerant from the main refrigerant circuit 56k that has been compressed and heated to the intermediate pressure merges with the refrigerant in the injection circuit 60c (point J in FIG. 10), and the temperature of the refrigerant from the main refrigerant circuit 56k decreases (point in FIG. 10). L). Then, the refrigerant whose temperature has decreased (point L in FIG. 11) is further compressed by the compressor 49, heated to high temperature and high pressure (point A in FIG. 10), and discharged from the compressor 49 to the main refrigerant circuit 56a. .

In addition, the heat pump apparatus 100 of this invention does not need to perform an injection driving | operation. When the injection operation is not performed, the expansion mechanism 59 should be closed and the refrigerant should not flow into the injection pipe of the compressor 49. Note that the opening degree of the expansion mechanism 59 may be controlled by a microcomputer or the like.

Next, the operation of the heat pump device 100 when performing a cooling operation (when operating as a freezer) will be described with reference to FIG. 10-2.

First, the refrigerant in the gas phase is compressed by the compressor 49, resulting in a high temperature and high pressure (point A in FIG. 10).

The high-temperature and high-pressure refrigerant is discharged from the compressor 49 to the main refrigerant circuit 56a, passes through the four-way valve 57, and the refrigerant in the main refrigerant circuit 56b that passes through the four-way valve 57 is transferred to the heat exchanger 55. . The transferred refrigerant in the main refrigerant circuit 56b is cooled and liquefied by heat exchange in the heat exchanger 55 (point B in FIG. 10). That is, the heat exchanger 55 functions as a condenser and a radiator in the main refrigerant circuit.

The refrigerant in the main refrigerant circuit 56c liquefied by the heat exchanger 55 is transferred to the expansion mechanism 54 and depressurized, so that it enters a gas-liquid two-phase state (point C in FIG. 10).

The refrigerant in the main refrigerant circuit 56d in the gas-liquid two-phase state is transferred to the internal heat exchanger 53, and heat is exchanged with the refrigerant transferred from the injection circuit 60b to the injection circuit 60c in the internal heat exchanger 53. It is cooled and liquefied (point D in FIG. 10). Here, the refrigerant transferred from the injection circuit 60b is decompressed by the expansion mechanism 59 and is in a gas-liquid two-phase state (point I in FIG. 10). The refrigerant (point D in FIG. 10) of the main refrigerant circuit 56e heat-exchanged by the internal heat exchanger 53 branches into the main refrigerant circuit 56f and the injection circuit 60a at a point P in FIG. 9-2.

In the receiver 52, the refrigerant in the main refrigerant circuit 56f is heat-exchanged with the refrigerant transferred from the main refrigerant circuit 56j to the main refrigerant circuit 56k and further cooled (point E in FIG. 10).

The refrigerant in the main refrigerant circuit 56g cooled by the receiver 52 is decompressed by the expansion mechanism 51 and enters a gas-liquid two-phase state (point F in FIG. 10).

The refrigerant in the main refrigerant circuit 56h that has been in the gas-liquid two-phase state by the expansion mechanism 51 is heat-exchanged by the heat exchanger 50 and heated (point G in FIG. 10). At this time, the water in the water circuit 61a is cooled, and the cooled water in the water circuit 61b is used for cooling or freezing. That is, the heat exchanger 50 functions as an evaporator in the main refrigerant circuit.

The refrigerant in the main refrigerant circuit 56i heated by the heat exchanger 50 passes through the four-way valve 57, and the refrigerant in the main refrigerant circuit 56j that passes through the four-way valve 57 flows into the receiver 52 and is further heated (FIG. 10). Point H). The refrigerant in the main refrigerant circuit 56k heated by the receiver 52 is transferred to the compressor 49.

On the other hand, the refrigerant in the injection circuit 60a branched at point P in FIG. 9-2 is decompressed by the expansion mechanism 59 (point I in FIG. 10). The refrigerant in the injection circuit 60b decompressed by the expansion mechanism 59 is heat-exchanged by the internal heat exchanger 53 to be in a gas-liquid two-phase state (point J in FIG. 10). Then, the refrigerant of the injection circuit 60 c heat-exchanged by the internal heat exchanger 53 is transferred from the injection pipe of the compressor 49 into the compressor 49. The subsequent compression operation in the compressor 49 is the same as in the heating operation. That is, the refrigerant that has been compressed and heated to a high temperature and high pressure (point A in FIG. 10) is discharged from the compressor 49 to the main refrigerant circuit 56a.

If the injection operation is not performed, the expansion mechanism 59 should be closed and the refrigerant should not flow into the injection pipe of the compressor 49. Note that the opening degree of the expansion mechanism 59 may be controlled by a microcomputer or the like.

In the above description, the heat exchanger 50 is described as being a heat exchanger (for example, a plate heat exchanger) that exchanges heat between the refrigerant in the main refrigerant circuit and the water in the water circuit. However, the heat exchanger 50 is not limited to this, and may exchange heat between the refrigerant and the air. Further, other fluid may flow in the water circuit instead of water.

As described above, the heat pump device according to the present invention can be applied to various heat pump devices using inverter compressors such as air conditioners and refrigerators. In addition, it is not limited to this, The heat pump apparatus concerning this invention can also be applied to a heat pump water heater and a refrigerator.

1,49 compressor, 2,57 four-way valve, 3, 5, 50, 55 heat exchanger, 4, 51, 54, 59 expansion mechanism, 6 refrigerant piping, 7 compression mechanism, 8 motor, 9 inverter unit, 10 inverter Control unit, 11 refrigerant compression operation mode control unit, 12 d-axis, q-axis current detection unit, 13 voltage command calculation unit, 14 drive signal generation unit, 15 amplitude phase determination unit, 16 rotation speed and load calculation unit, 16a table, 17 Detection circuit with filter function, 18 phase current calculation unit, 19 3 phase 2 phase conversion unit, 20 refrigeration cycle unit, 24 PWM signal generation unit, 25 2 phase 3 phase conversion unit, 26a, 26b current sensor, 27a-27f switching Element, 30 detection circuit switching unit with filter function, 31 secondary side resistance switching unit, 34 motor current waveform, 35 ACCT output waveform, 4 , 40a amplifier output waveform, 41, 41a actual current waveform, 42, 42a ACCT output waveform, 43a, 43b resistance element, 44 amplifier, 45 microcomputer, 52 receiver, 53 internal heat exchanger, 56a-56k main refrigerant circuit, 58 fan , 60a-60c injection circuit, 61a, 61b water circuit, 100 heat pump device, S1-S3 steps.

Claims

A compressor driven by a motor to compress the refrigerant;
An inverter for applying a voltage to the motor;
A current sensor that detects current flowing in the motor and includes two secondary resistances having different resistance values;
An inverter control unit that outputs a drive signal to the inverter unit,
The inverter control unit
A current detector for inputting the current detected by the current sensor;
A voltage command calculation unit that calculates a voltage command value based on a signal from the current detection unit;
A drive signal generator for generating the drive signal based on the voltage command value;
A rotational speed and a load for calculating the rotational speed and load of the motor,
The drive signal generator is
An amplitude phase determining unit that determines a necessary refrigerant compression amount of the compressor based on a signal from the current sensor, determines an amplitude and a phase from the necessary refrigerant compression amount, and causes the drive signal generation unit to generate the drive signal; ,
The current detection unit includes a filter circuit and a detection circuit, and includes a detection circuit with a filter function for removing harmonic noise,
The rotation speed and load calculation unit performs switching between the filter circuit and the detection circuit of the detection circuit with a filter function according to whether the rotation speed or load of the motor is equal to or less than a set value,
A heat pump device that corrects a phase difference of an output signal of the detection circuit with a filter function when a rotation speed or a load of the motor is equal to or less than a set value.
The inverter control unit has a storage area,
The heat pump apparatus according to claim 1, wherein a correction signal corresponding to a resistance value of the secondary resistance of the current sensor is stored in the storage area.
The heat pump device according to claim 1 or 2, wherein the filter circuit of the detection circuit with a filter function is a digital filter or an analog filter that removes or reduces harmonic noise of a signal from the current sensor. .
The heat pump device according to any one of claims 1 to 3, wherein at least one of the switching elements provided in the inverter unit is formed of a wide band gap semiconductor.
The heat pump device according to any one of claims 1 to 3, wherein a diode constituting the switching element provided in the inverter unit is formed of a wide band gap semiconductor.
The wide band gap semiconductor is
6. The heat pump device according to claim 4, wherein the heat pump device is silicon carbide, gallium nitride-based material, or diamond.
An air conditioner including the heat pump device according to any one of claims 1 to 6.
A refrigerator equipped with the heat pump device according to any one of claims 1 to 6.