WO2006075742A1 - Heat pump application device and power recovering device using expander - Google Patents

Abstract

A heat pump application device (500) comprises a compressor (501) for compressing a cooling medium, a motor (505) for operating the compressor (501), a radiator (502) for cooling the cooling medium compressed by the compressor (501), an expander (503) for expanding the cooling medium passing through the radiator (502), an evaporator (504) for evaporating the cooling medium expanded by the expander (503), a generator (507) connected to the expander (503) to generate power with the expansion energy of the cooling medium, and a variable speed converter (508) for converting the AC power generated by the generator (507) into DC power to regenerate power supplied to the motor (505). The variable speed converter (508) conduct a control to reduce the voltage on the PC power line (DL1, DL2) for regenerated power below a threshold.

Description

 Power recovery device using heat pump application equipment and expander

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a heat pump application device having a function of recovering expansion energy of a refrigerant in the form of electric energy, and a power recovery device suitable for the heat pump application device.

 Background art

 [0002] A vapor compression refrigeration apparatus, which is a representative example of heat pump application equipment, has a configuration shown in FIG. The refrigeration apparatus shown in FIG. 16 includes a compressor 101, a radiator 102, an expansion valve 103, and an evaporator 104. These elements are connected by piping, and the refrigerant moves as indicated by the white arrows in the figure.

 [0003] The operation principle of the refrigeration apparatus is as follows. The pressure and temperature of the refrigerant vapor is increased by the compressor 101. The refrigerant vapor then enters the radiator 102 where it is cooled. Thereafter, the high-pressure refrigerant is reduced to the evaporation pressure by the expansion valve 103, vaporizes in the evaporator 104, and absorbs heat from the surroundings of the evaporator 104. Then, the refrigerant vapor returns to the compressor 101 through the outlet of the evaporator 104. As this refrigerant, for example, carbon dioxide with a low global warming coefficient without destroying the ozone layer may be used.

 [0004] However, a refrigeration system using carbon dioxide as a refrigerant has a lower coefficient of performance (COP: Coefficient Of Performance) indicating energy efficiency than a refrigeration system using chlorofluorocarbon as a refrigerant. Considering capacity, more power is required than refrigeration equipment using chlorofluorocarbon as a refrigerant. Therefore, a lot of fossil fuel is required as energy, and even if the global warming potential of the refrigerant itself is small, a lot of carbon dioxide is discharged as a result. Thus, several proposals have been made to improve the COP of a refrigeration system using carbon dioxide and carbon dioxide as a refrigerant.

[0005] As an example of the above proposal, there is a refrigeration apparatus (see Japanese Patent Application Laid-Open No. 2000-241033) shown in FIG. In this refrigeration apparatus, the refrigerant is compressed by a compressor 201 driven by a motor 205, cooled by a radiator 202, and sucked into an expander 203. Expander 203 The refrigerant expanded in the evaporator 206 absorbs heat from the outside in the evaporator 206 and vaporizes, and then returns to the compressor 201 again. The generator 204 attached to the expander 203 rotates with the expansion energy of the refrigerant to generate power. The rotation speed control means 212 is based on the outputs of the pressure sensor 210 and the temperature sensor 211 so that the outlet pressure of the radiator 202 becomes the optimum high pressure value calculated by the calculation means 209, that is, the power generation amount of the generator 204, that is, the expansion Controls the speed of the machine 203. An oil separator 207 and an accumulator 208 are installed before and after the compressor 201 to improve performance and reliability.

[0006] By generating a power by driving a generator with the expansion energy of the refrigerant and effectively using the power, the amount of energy used can be reduced comprehensively. As a result, COP of refrigeration equipment is improved.

 FIG. 18 is a block diagram showing a conventional power recovery device using an expander. In FIG. 18, the AC voltage from the AC power supply 301 is converted into a DC voltage by the rectifier circuit 302. The direct voltage is smoothed by the smoothing capacitor 303 and then converted into a three-phase AC voltage by the motor driving device 304. The motor 306 is driven by the three-phase AC voltage. Then, the compressor 307 performs a compression function by driving the motor 306.

 [0008] The motor driving device 304 includes a switching element group 305 for converting a DC voltage into an AC voltage. Arbitrary alternating current can be output by turning on and off the switching element group 305 by a PWM (Pulse Width Modulation) method so as to realize a predetermined alternating frequency.

On the other hand, the generator 310 installed for recovering power by the expander 311 has a variable speed comparator 308 for converting the three-phase AC power generated by the generator 310 into DC power. It is connected. The variable speed converter 308 converts the AC power generated by the generator 310 into DC power and switches the switching element group 309 by the PWM method to rotate the generator 310 at a given target rotational speed. By controlling the rotational speed of the generator 310, the rotational speed of the expander 311 can be controlled. Further, the DC power line from the variable speed converter 308 is connected in parallel to the DC power line for supplying power to the motor 306. The electric power regenerated from the variable speed converter 308 is consumed by the motor 306 on the compressor 307 side via the motor driving device 304. [0010] As disclosed in Japanese Patent Application Laid-Open No. 2002-354896, in the field of wind power generation, a technique for keeping the output voltage of a generator constant is known.

 Disclosure of the invention

 By the way, in the power recovery apparatus of FIG. 18, the power supplied from AC power supply 301 via rectifier circuit 302 is Win, the power consumed by motor 306 is Wm, and the power regenerated by variable speed converter 308 If Wg is Wg, the following (Equation 1) holds. Normally, the power consumption Wm is larger than the regenerative power Wg, so the power supplied Win from the AC power supply 301 is a positive value.

 Win + Wg = Wm-.. (Formula 1)

 [0012] However, if the relationship of (power consumption Wm)> (regenerative power Wg) always holds, this is not always the case. For example, when the system is started, stopped, when the compressor decelerates, or when the state of the heat exchanger changes suddenly, there is a period in which the regenerative power Wg is greater than the power consumption Wm, although it is a short time. There is a case. The rectifier circuit 302 is usually a full-wave rectifier circuit configured by a diode bridge, and does not have a function of regenerating power in the AC power supply 301. Therefore, if a situation occurs where the regenerative power Wg exceeds the power consumption Wm, the smoothing capacitor 303 alone cannot absorb the excess power immediately, and the voltage of the DC power line rises abnormally. There is a risk of damaging electrical components such as.

 In view of the above circumstances, an object of the present invention is to improve the reliability of a heat pump application device by preventing an excessive voltage increase in a direct current power line when regenerative power exceeds power consumption. To do. Another object of the present invention is to improve the reliability of a power recovery device suitable for such heat pump application equipment.

[0014] That is, the present invention provides

 A compressor for compressing the refrigerant;

 A motor for operating the compressor;

 A radiator that cools the refrigerant compressed by the compressor;

 An expander that expands the refrigerant that has passed through the radiator;

An evaporator for evaporating the refrigerant expanded by the expander; A generator that is connected to the expander and generates power using the expansion energy of the refrigerant; and a DC power output means that converts AC power generated by the generator into DC power and regenerates it to the motor side;

 Voltage suppression means for suppressing the voltage of the DC power line, where the DC power output means regenerates power, to less than a predetermined value;

 The heat pump application equipment provided with is provided.

 [0015] The heat pump application device of the present invention is provided with voltage suppression means for suppressing the voltage of the DC power line below a predetermined value. In this way, it is possible to prevent excessive voltage rise in the DC power line regardless of the operating state of the compressor or the expander. As a result, it is possible to prevent electrical components such as capacitors and diodes arranged in the direct current voltage line from being destroyed, thereby realizing a highly reliable heat pump application device. The predetermined value may be a threshold voltage set slightly higher than the power supply voltage for supplying power to the motor.

 [0016] In another aspect, the present invention provides:

 An expander for expanding the working fluid;

 A generator that is connected to the expander and generates power with the expansion energy of the working fluid; a DC power output means that converts the AC power generated by the generator into DC power and outputs the output voltage; and the output voltage of the DC power output means exceeds a predetermined value A power recovery device having generator control means for executing control to reduce the power generation efficiency of the generator

[0017] In the power recovery apparatus of the present invention, when the output voltage of the DC power output means becomes a predetermined value or more, the generator control means performs control to reduce the power generation efficiency of the generator. In this way, it is possible to prevent the output voltage of the DC power output means from rising excessively, and to prevent the parts of the electric circuit (for example, capacitors and diodes) connected to the power recovery device from being destroyed. Can do. That is, according to the present invention, the reliability of the power recovery device using the expander is increased.

[0018] Further, in the power recovery apparatus, instead of the generator control means or the power generation thereof In addition to the machine control means, there may be provided voltage suppression means for starting the storage or power consumption upon receiving the power supply from the DC power output means power when the output voltage of the DC power output means becomes a predetermined value or more.

[0019] Further, in the power recovery apparatus, the generator control means may be configured to execute a control for reducing the power generation efficiency when the output voltage of the DC power output means exceeds a predetermined value. May be configured to perform control to reduce the rotational speed.

 Brief Description of Drawings

 FIG. 1 is a block diagram showing a heat pump application device according to a first embodiment of the present invention.

 FIG. 2A is a schematic cross-sectional view of a typical SPMSM (Surface Permanent Magnet Synchronous Motor).

 FIG. 2B is a schematic cross-sectional view of a typical IPMSM (Interior Permanent Magnet Synchronous Motor).

 [FIG. 3] FIG. 3 is a diagram for explaining a correlation among a radiator outlet pressure, a radiator outlet temperature, and a refrigeration cycle efficiency.

 FIG. 4 is a flowchart of a process for determining the rotation speed of the expander.

 FIG. 5 is a block diagram showing a detailed configuration of a variable speed converter.

 FIG. 6 is a characteristic diagram illustrating the relationship between current phase angle and torque in IPMSM.

[FIG. 7A] FIG. 7A is a diagram showing a relationship between three-phase AC coordinates and two-phase AC coordinates.

 FIG. 7B is a diagram showing the relationship between the two-phase AC coordinate and the dq coordinate.

 FIG. 8 is a diagram showing a current phase angle β on dq coordinates.

 FIG. 9 is a characteristic diagram showing loss characteristics of the permanent magnet type synchronous generator.

 FIG. 10 is a flowchart of processing for determining a current phase angle.

 FIG. 11 is a characteristic diagram showing the principle of setting the current phase angle.

 FIG. 12 is a block diagram showing a heat pump application device of a second embodiment.

FIG. 13 is a characteristic diagram showing a change in voltage of a DC power line in the heat pump application device of the second embodiment. FIG. 14 is a block diagram showing a heat pump application device of a third embodiment.

 FIG. 15 is a characteristic diagram showing a change in voltage of a DC power line in the heat pump applied device of the third embodiment.

 FIG. 16 is a block diagram showing a conventional vapor compression refrigeration apparatus.

 FIG. 17 is a block diagram showing a conventional refrigeration air conditioner using an expander.

 FIG. 18 is a block diagram showing a conventional power recovery apparatus using an expander. BEST MODE FOR CARRYING OUT THE INVENTION

In the heat pump application device of the present invention, the following preferred embodiments can be adopted.

[0022] That is, in the heat pump application device of the present invention described above, the voltage suppression means can also be used as a generator control means for controlling the drive of the generator.

[0023] Specifically, the generator control means executes control for reducing the power generation efficiency of the generator when the voltage of the DC power line becomes equal to or higher than a predetermined value.

More preferably, a permanent magnet type synchronous generator is adopted as the generator. Furthermore, the heat pump application device of the present invention can be provided with a variable speed converter including DC power output means and generator control means. The variable speed converter changes the current phase angle of the permanent magnet type synchronous generator so that the permanent magnet type synchronous generator moves from a high efficiency state to a low efficiency state. Execute control.

 [0025] The voltage increase of the DC power line can also be prevented by applying the same control as the generator to the motor connected to the compressor. That is, the voltage suppression means in the heat pump application device of the present invention can also be used as a motor control means for controlling the driving of the motor.

 [0026] Specifically, the motor control means executes control for reducing the driving efficiency of the motor when the voltage of the DC power line becomes equal to or higher than a predetermined value.

 More preferably, a permanent magnet type synchronous motor is employed as the motor. In this case, the motor control means can be composed of an inverter that executes PWM control. The inverter executes control to change the current phase angle of the permanent magnet type synchronous motor, and changes the permanent magnet type synchronous motor from the high efficiency driving state to the low efficiency driving state.

[0028] Further, in the heat pump application device of the present invention, the voltage suppression means described above may be a DC power supply. When the Kaline voltage exceeds the specified value, storage or consumption of the power supplied to the DC power line is started.

 [0029] Specifically, the voltage suppression means is composed of a load and a switch for turning on and off the power supply to the load. When the voltage of the DC power line exceeds a predetermined value, Power supply from the power output means to the load is started.

 [0030] (First embodiment)

 Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The main explanation items and the explanation order of the first embodiment are as follows.

 1. Configuration of heat pump application equipment

 2. Operation of heat pump application equipment (refrigeration cycle)

 3. Operation of heat pump application equipment (power regeneration)

 4.Expansion machine rotation speed determination procedure

 5. Detailed configuration of variable speed converter

 6.Operation of variable speed converter

 7. Estimation of rotor position Θ

 8.Control when regenerative power exceeds power consumption

[0031] 1. Configuration of heat pump application equipment

 FIG. 1 is a block diagram showing a heat pump application device according to a first embodiment of the present invention. The heat pump application device 500 includes a compressor 501 that compresses refrigerant, a radiator 502 that cools the refrigerant compressed by the compressor 501, an expander 503 that expands the refrigerant that has passed through the radiator 502, and an expander An evaporator 504 for evaporating the refrigerant expanded by 503 and a refrigerant pipe 518 for circulating the refrigerant between the above elements are provided. The compressor 501 and the expander 503 are, for example, a rotary type or a scroll type.

[0032] In addition, the heat pump application device 500 includes a motor 505 that drives the compressor 501, and an inverter 506 that serves as a motor control unit that converts direct current into alternating current having a predetermined frequency and controls driving of the motor 505. I have. The inverter 506 is a so-called three-phase voltage type inverter.

[0033] The motor 505 is, for example, a permanent magnet type synchronous motor (so-called DC brushless' motor). is there. Permanent magnet synchronous motors are surface permanent magnet synchronous motor (SPMSM) with magnets attached to the rotor surface, and embedded permanent magnet synchronous motors with a permanent magnet embedded in the inner rotor | 5 (IPMSM: Interior Permanent Magnet Synchronous Motor) Figure 2A shows the cross-sectional structure of a typical SPMSM rotor. Figure 2B shows the cross-sectional structure of a typical IPMSM rotor. In the SPMSM of Fig. 2A, the part where the permanent magnet exists can be regarded as magnetically equivalent to the air gap, so the magnetic resistance becomes independent of the rotor position, and the d-axis inductance Ld and q-axis of the armature winding A non-salient pole machine with the same inductance Lq. On the other hand, the IPMSM in Fig. 2B has the same magnetic flux as the air gap in the magnetic path of the magnetic flux in the d-axis direction created by the armature winding. This magnetic flux can pass through the steel sheet, so the reluctance in this direction is small. This results in a salient pole machine with (d-axis inductance Ld) <(q-axis inductance Lq). IPMSM has the advantage that it can be driven with extremely high efficiency because reluctance torque can be used in addition to magnet torque. Therefore, IPMSM is recommended for motor 505. The IPMSM is also preferable for the generator 507.

On the other hand, the inverter 506 drives the motor 505 by sine wave PWM control in which a current having a waveform close to a sine wave is passed through each phase. In the 120 ° energization method that switches the phase through which the current flows every 120 ° according to the magnetic pole position, torque irregularities are likely to occur when the current is switched due to the inductance of the armature winding. In order to suppress such torque unevenness and drive the motor 505 (permanent magnet synchronous motor) with low noise and high efficiency, a 180 ° energization type sinusoidal current drive is suitable.

 [0035] If the field is a sine wave magnetic flux to reduce torque unevenness, the torque constant of each phase becomes a sine wave. Therefore, when a sinusoidal current is passed through each phase, the generated torque T of the motor does not depend on the rotation angle of the rotor, as shown in the following equation.

 T = Ksin Θ -Isin Q

 + Ksin (θ-2 π / 3) -Isin (θ—2 π / 3)

 + Ksin (θ 4 π / 3) -Isin (θ—4 π / 3)

= (3/2) ΚΙ Where K is the torque constant (maximum phase value), I is the armature current (maximum phase value), and Θ is the rotor position (rotation angle).

 [0036] Here, between the rotor position Θ [°], the rotational angular velocity Ω [radZs], and the time t [s], Θ =

 Therefore, it is necessary to calculate the amount of 3-phase alternating current that changes from moment to moment, which is very difficult to handle. Therefore, in order to simplify the calculation, a so-called vector control method is widely used, which uses a rotational coordinate transformation (dq transformation) to control the current flowing through each phase. Further, according to the vector control method, the current flowing through the motor 505 can be controlled separately for the d-axis and the q-axis, so that the motor capacity can be maximized.

 [0037] Returning to FIG. The heat pump application device 500 further includes a temperature sensor 516 that detects the outlet temperature of the radiator 502, a pressure sensor 517 that detects the outlet pressure of the radiator 502, and a microcomputer 509. The detection signals of the temperature sensor 516 and the pressure sensor 517 are binarized by AZD conversion (not shown) and input to the microcomputer 509. The microcomputer 509 plays the role of an expander rotation speed determination means for determining the rotation speed of the expander 503 based on inputs from the sensors 516 and 517. However, the microcomputer 509 that sets the target rotational speed of the expander 503 may also be used as the microcomputer that constitutes the control system of the variable speed converter 508.

 [0038] The heat pump application device 500 functions as a generator 507 connected to the expander 503 and generating electricity with the expansion energy of the refrigerant, and a generator control means for controlling the drive of the generator 507. And a variable speed converter 508. As with the motor 505, a permanent magnet synchronous motor such as SPMSM or IPMSM can be used for the generator 507. The variable speed converter 508 also serves as a DC power output means that converts AC power generated by the generator 507 into DC power and regenerates it to the motor 505 side. The variable speed converter 508 is a three-phase voltage type similar to the inverter 506, and controls the generator 507 by sinusoidal PWM control. The expander 503, the generator 507, and the variable speed converter 508 constitute a power recovery device 601 in the heat pump application device 500.

In the present specification, the terms “inverter” and “converter” include an “inverted” converter including a control system such as a microcomputer that controls driving of the motor 505 and the generator 507, respectively. -Used to mean 'do'. In general, regenerative This means that the electric power is returned to the power source. In this specification, the motor that drives the compressor 501 by recovering the expansion energy of the refrigerant by the expander 503 and the variable speed converter 508 and converting it into electric energy. It means to supply to the 505 side.

[0040] The heat pump application device 500 includes a rectifier circuit 511 and a smoothing capacitor 512 that convert AC power of the AC power supply 510 into DC power. The rectifier circuit 511 is a general full-wave rectifier circuit using a diode bridge. There is no circuit for returning power to AC power supply 510. Variable speed converter 508 power DC power line DL, rectified circuit

 Connected in parallel to the DC power line DL between 2-way 511 and inverter 506, from generator 507

 1

 Power is supplied to the inverter 506, and the energy recovered by the expander 503 is used as part of the driving force of the compressor 501.

[0041] Further, the DC power lines DL and DL detect the voltages of the DC power lines DL and DL.

 1 2 1 2

 For this purpose, a first voltage detection sensor 520 and a second voltage detection sensor 521 are arranged. However, the first voltage detection sensor 520 may be included in the variable speed converter 508, and the second voltage detection sensor 521 may be included in the inverter 506. Further, each of the voltage detection sensors 520 and 521 may be configured as a voltage detection unit including an AZD change. Normally, one sensor is sufficient to detect the voltage of the DC power lines DL and DL.

 1 2

 In such cases, it is desirable to provide one on each substrate.

 [0042] 2. Operation of heat pump application equipment (refrigeration cycle)

 In FIG. 1, a compressor 501 is driven by a motor 505 controlled by an inverter 506, and the refrigerant is compressed by the compressor 501. The compressed refrigerant is cooled by the radiator 502 and then passes through the expander 503 connected to the generator 507 controlled by the variable speed converter 508. At this time, the refrigerant expands in the expander 503, absorbs heat from the outside in the evaporator 504 and vaporizes, and then returns to the compressor 501 again.

 [0043] 3. Operation of heat pump equipment (power regeneration)

In Fig. 1, the DC power obtained by rectifying the AC power from the AC power source 510 by the rectifier circuit 511 is smoothed by the smoothing capacitor 512, and then 3% by the inverter 50 6 It is converted into phase AC power and supplied to the motor 505. Thereby, the motor 505 is driven and the compressor 501 performs the compression function. [0044] The torque of the expander 503 generated by the expansion force of the refrigerant is transmitted to the generator 507 through the shaft. In the generator 507, the rotor fixed to the shaft rotates to generate power. The AC power generated by the generator 507 is converted to DC power by the variable speed converter 508 and then supplied to both ends of the smoothing capacitor 512. As a result, the electric power generated by the expander 503 and the generator 507 is consumed by the motor 505 that drives the compressor 501.

 [0045] 4. Procedure for determining the rotational speed of the expander

 The rotational speeds of the expander 503 and the generator 507 are controlled by a variable speed converter 508. The target speed is given to the variable speed converter 508 from the microcomputer 509. The microcomputer 509 determines the target rotational speed of the expander 503 based on the radiator outlet temperature obtained from the temperature sensor 516 and the radiator outlet pressure obtained from the pressure sensor 517 so that the refrigeration cycle efficiency is maximized. Then, control the high-pressure side pressure (radiator outlet pressure) of the refrigeration cycle.

 [0046] FIG. 3 is a diagram illustrating the interrelationship between the radiator outlet pressure, the radiator outlet temperature, and the refrigeration cycle efficiency. The maximum efficiency of the refrigeration cycle of the heat pump application device 500 depends on the radiator outlet pressure and the radiator outlet temperature. The line connecting the maximum points is the optimum efficiency pressure line in the figure.

FIG. 4 is a flowchart of a process for determining the rotation speed of the expander. Microcomputer 509 first samples the sensor signals from temperature sensor 516 and pressure sensor 517. These sensor signals are signals that have been binarized by AZD variation (not shown). Further, the microcomputer 509 calculates a radiator outlet pressure and a radiator outlet temperature from the acquired sensor signal (S101). Next, the optimum pressure that maximizes the refrigeration cycle efficiency is calculated according to the data shown in FIG. 3 (S102). Specifically, a database for specifying the correspondence relationship between the radiator outlet pressure, radiator outlet temperature, and refrigeration cycle efficiency, that is, the graph of FIG. . In the process of S102 in the flowchart, the optimum pressure that maximizes the refrigeration cycle efficiency is found by referring to the database. The quantization width when creating the database in Figure 3 as the database is as follows: temperature sensor 516 and pressure sensor 517. It should be determined by the resolution. Note that an approximate function F (p, t) of the optimum efficiency pressure line shown in FIG. 3 is found in advance and is given to the microcomputer 509. The approximate function F (p, t) includes the radiator outlet pressure and the radiator. By substituting the outlet temperature, the optimum pressure that maximizes the refrigeration cycle efficiency may be calculated.

 [0048] Next, the deviation between the current radiator outlet pressure and the optimum pressure is examined (S103). If the current radiator outlet pressure is larger than the optimum pressure, the target rotational speed of the expander 503 is set larger than the current target rotational speed so that the radiator outlet pressure is reduced (S104). Then, the set target rotational speed is output to variable speed converter 508 (S105). On the other hand, if the current radiator outlet pressure is lower than the optimum pressure, the target rotational speed of the expander 503 is set smaller than the current target rotational speed so that the radiator outlet pressure increases, and the target The number of revolutions is output to variable speed converter 508 (S 106, S 105). Although not shown in the flowchart, when the current radiator outlet pressure matches the optimum pressure, the current target rotational speed may be maintained. With these controls, the pressure at the radiator outlet is controlled to maximize refrigeration cycle efficiency.

 It should be noted that the rotational speed determination procedure as described above can also be adopted when determining the target rotational speed of the compressor 501.

 [0050] 5. Detailed configuration of variable speed converter

 The configuration and operation of variable speed converter 508 will be described in detail. FIG. 5 is a detailed block diagram of the variable speed converter 508 of the heat pump application device 500 shown in FIG.

[0051] The variable speed converter 508 includes a conversion circuit unit 508a as a DC power output means that converts AC power generated by the generator 507 into DC power and regenerates the motor 505, and a control circuit that generates a PWM signal. Part 508b. The conversion circuit section 508a includes a u-phase current sensor 805a, a V-th current sensor 805b, switching elements 803a, 803b, 803c, 803d, 803e, 803f and freewheeling diodes 804a, 804b, 804c, 804d, 804e, 804f. Including. The current sensor only needs to be able to measure the current value of any two of the three phases u, V, and w. The switching elements 803a to 803f are power MOSFETs or IGBTs (Insulated Gate Bipolar Transistors). The control circuit unit 508b can also be configured by an analog circuit centered on a force operational amplifier generally configured by a microcomputer. Control circuit The microcomputer 508b as the unit 508b includes a biaxial current conversion means 806, a rotor position rotation speed estimation means 807, a base driver 808, a sine wave voltage output means 809, a current control means 810, a current command creation means 811, and a rotation speed. It includes a control means 812 and a current phase angle determination means 815, and applies the created PWM signal to the switching elements 803a to 803f. In the present embodiment, each of these means means a program module that can be executed by the microcomputer 508b (control circuit unit 508b).

[0052] The three-phase AC output from the generator 507 is supplied to, for example, the DC power source 801 side via the variable speed converter 508. The DC power source 801 corresponds to the output of the rectifier circuit 51 1 in FIG. Further, the three-phase AC output is converted to DC by the variable speed converter 508. At that time, control is performed so that the rotational speed of the generator 507 becomes the target rotational speed based on the target rotational speed given from the outside (the microcomputer 509 in the present embodiment).

 That is, variable-speed converter 508 has switching patterns of switching elements 803a to 803f, a magnetic pole position (rotor position Θ) of generator 507, an estimated rotational speed ω m of generator 507, a microcomputer 509 It is determined based on the target rotational speed given by the force and the detection results of the phase currents iu, iv by the current sensors 805a, 805b. Further, a switching pattern signal corresponding to the determined switching pattern is sent to the base driver 808. The switching pattern signal is converted into a drive signal (PWM signal) for electrically driving the switching elements 803a to 803f by the base dryer 808, and each switching element 803a to 803f operates according to these drive signals. To do.

 [0054] 6. Operation of Variable Speed Converter

 Next, the operation of the variable speed converter 708 will be described. However, in this item 6, control is performed when the voltage of the DC power lines DL and DL does not exceed the predetermined threshold voltage.

 1 2

 Is explained. When the voltage of the DC power lines DL and DL exceeds the above threshold voltage

 1 2

 This control is described in item 8.

[0055] First, in order to realize the target rotational speed ω * given by the microcomputer 509, the deviation force from the current rotational speed ω (estimated rotational speed co m described later) is also determined by Based on 2), it is calculated by the rotational speed control means 812 (rotational speed control program). Calculation method The method is based on the general PI control method.

 I * = Gpco X (ω * i) + Gico X∑ (ω * — ω)… (Formula 2)

 Where Gp ω is the speed control proportional gain, Gico is the integral gain, ω is the current rotational speed, ω * is the target rotational speed, and I * is the current command.

 [0056] Further, the current command creation means 811 (current command creation program) acquires the current command value I * calculated by the rotation speed control means 812, and the d-axis current command Id for realizing the current phase angle. *, Q-axis current command Iq * is calculated using the following formula. Specifically, Id * and Iq * are obtained by substituting the optimal current phase angle β into (Equation 3) and (Equation 4).

 Id * = I * Xsin (jS) ... (Formula 3)

 Iq * = I * X cos (j8)… (Formula 4)

 Where β is the current phase angle.

 [0057] For example, when the motor 505 or the generator 507 is SPMSM, the d-axis current Id does not contribute to the torque, so that the d-axis current ld = 0 (that is, β = 0) is the maximum efficiency operation. On the other hand, in the case of IPMS リ, if ld = 0, the reluctance torque cannot be used, so the total generated torque does not become maximum at the current phase angle β = 0 °. FIG. 6 is a diagram illustrating the relationship between the current phase angle of IPMSM with a constant current value and the number of pole pairs = 2 and the torque. Magnet torque Tm is maximum when j8 = 0 °. Reluctance torque Tr is maximum at | 8 = 45 ° and –135 °. As a result, the total generated torque T becomes maximum when the current phase angle is in the range of 0 ° <| 8 <45 °.

 [0058] Thus, it can be seen that both SPMSM and IPMSM have a current phase angle that can maximize the generated torque for the same current. Conversely, there is a current phase angle that can maximize the current that can be extracted for the same torque. Therefore, it is usually possible to adopt ld = 0 control of | 8 = 0 ° for SPMSM so that the power generation efficiency is the highest. In this case, the current phase angle determination means 815 (current phase angle determination program) passes | 8 = 0 ° to the current command creation means 811.

Here, the power generation efficiency (= power recovery efficiency) means the ratio between the input and output of the generator 507. The input of generator 507 is the product of rotational speed and torque, and the output is the product of voltage and current. When discussing the driving efficiency of the motor 505, the input and output are the opposite of the case of the generator 507. [0060] On the other hand, in the case of IPMSM, it is necessary to operate at an optimal current phase angle β that is determined according to device constants (number of pole pairs, flux linkage, d-axis inductance, q-axis inductance, etc.) and current value. . The current phase angle determining means 815 obtains the optimum current phase angle j8 according to the device constant and the current value. Theoretically, when a certain driving condition is given, the calculation is performed to find the current phase angle β that minimizes the loss of IPMSM. However, the calculation is complicated, and a processor with high processing capability is required to perform the calculation within a given time. Therefore, for example, the optimal current phase angle j8 corresponding to the current value is obtained in advance by simulation or experiment, and an approximation function or lookup table for obtaining the optimal current phase angle β based on the results is prepared. In addition, it is possible to adopt a method of finding the optimum current phase angle β from these approximate functions and look-up tables and the current command value I * obtained by the rotation speed control means 812.

 [0061] By the way, the inverter 506 and the variable speed converter 508 can actually control the u-phase, V-phase, and w-phase voltages of the motor 505 and the generator 507, and can detect the u-phase and ν-phase voltages. Current and rotor position Θ. Therefore, the current flowing in the d-axis and q-axis is calculated based on the current values of the u-phase and V-phase, and then the u-phase, V-phase, and w-phase voltages are derived, and the u-phase, V-phase, and w-phase voltages are derived. The method of controlling the sine wave current is adopted. Such a method is called a vector control method because the current flowing through the motor is regarded as a current vector on the dq coordinate, and is widely used for brushless motor control.

 [0062] As specific processing, first, the phase currents iu, iv of the generator 507 detected by the current sensors 805a, 805b are contributed to the magnet torque of the generator 507 by the biaxial current conversion means 806. q-axis current Iq and d-axis current Id orthogonal to it are converted into 2-axis current. The d-axis is usually in the direction of the magnetic flux generated by the field.

 [0063] The 2-axis current conversion means 806 (2-axis current conversion program) first converts the 3-phase AC coordinates (u—V—w) to 2-phase AC coordinates (a—b) as shown in FIG. 7A. I do. This transformation is given by the following matrix [c] (Equation 5). However, in the three-phase AC coordinate currently handled, i u + iv + iw = 0 holds, so the third row of matrix [c] can be ignored.

[0064] [Equation 1] (5)

[0065] From (Equation 5) above, the current ia, ib on the fixed two-phase AC coordinate is expressed by the following (Equation 6) _c where iw = ― (iu + iv).

[0066] [Equation 2]

(Equation 6)

[0067] Further, as shown in FIG. 7B, conversion from fixed two-phase AC coordinates (ab) to rotating d-q orthogonal coordinates is performed. This conversion is expressed by the following (Equation 7) using the rotor position 0 (the estimated magnetic pole position described later). The values of sin θ and cos Θ can be obtained by referring to an appropriate lookup table.

 [0068] [Equation 3]

(Equation 7)

FIG. 8 is a diagram showing the current phase angle 13 on the dq coordinate. The current phase angle j8 is represented by the angle formed by the current vector I and the q-axis current Iq. The current vector I is the d-axis current Id and the q-axis current This is a composite vector with the flow Iq. In the case of SPMSM, optimal control is achieved when Id = 0 (| 8 = 0 °). In the case of IPMSM, by flowing a negative d-axis current, the magnetic flux in the d-axis direction can be reduced using the demagnetization effect due to the d-axis armature reaction, and equivalent field-weakening control can be realized.

 Returning to the block diagram of FIG. 5, the description will be continued. The current control means 810 (current control program) uses the current commands Id * and Iq * given from the current command creation means 811 and the current values Id and Iq given from the two-axis current conversion means 806 as follows ( Equation 8) Output voltages Vd and Vq are created by (Equation 9).

 Vd = Gpd X (Id * -Id) + Gid X∑ (Id * —Id)

 Vq = Gpq X (Iq * — Iq) + Giq X∑ (Iq * — Iq)… (Equation 9)

 Where Vd is d-axis voltage, Vq is q-axis voltage, Gpd is d-axis current control proportional gain, Gid is integral gain, Gpq is q-axis current control proportional gain, and Giq is integral gain.

 Next, the two-direction outputs Vd and Vq obtained as described above are the sinusoidal voltage output means 809.

 (Sine wave voltage output program) The sine wave voltage output means 809 obtains three-phase output voltages Vu, Vv, Vw so that the output waveform becomes a sine wave based on Vd, Vq on the d-q coordinate and the rotor position Θ. Specifically, by the rotation transformation and the two-phase three-phase transformation of (Equation 10) and (Equation 11) below, the voltage on the 1-coordinate ¥ (1, Vq is changed to the three-phase output voltage Vu, Vv, Vw. Convert.

 [0072] [Equation 4]

(Formula 1 0)

(Formula 1 1)

[0073] After obtaining the voltages Vu, Vv, Vw on the three-phase AC coordinates as described above, the switching patterns of the switching elements 803a to 803f were created from these three-phase voltages Vu, Vv, Vw. The switching pattern signal (duty value Du, Dv, Dw) corresponding to the switching pattern is output to the base driver 808. Then, the base driver 808 creates and outputs a PWM signal for driving the switching elements 803a to 803f in accordance with the switching pattern signal. Each switching element 803a to 803f operates according to the PWM signal, and the generator 507 is driven at the target rotation speed (speed).

[0074] 7. Estimation of rotor position Θ

 Next, the rotor position rotational speed estimation means 807 (rotor position rotational speed estimation program) will be described. In a general brushless motor control method, the rotor position 0 (magnetic pole position) is detected by a Hall element resolver. However, in the actual design of the heat pump application device 500 of the present invention, it is conceivable that the motor 505 and the generator 507 are arranged in the housing of the compressor 501 and the expander 503. This is because the problem of refrigerant leakage caused by exposing the shaft to the outside does not occur, reliability can be improved, and miniaturization and low cost are easy to achieve. The housings of the compressor 501 and the expander 503 are usually at high temperatures and pressures, and it is difficult for detectors such as Hall elements and resolvers to demonstrate their original performance. In addition, there is a problem that space constraints are large. Therefore, it is preferable to employ a so-called sensorless method in which the rotor position Θ of the motor 505 or the generator 507 is estimated from the induced voltage of the winding of each phase in the heat pump applied device 500.

 First, using the condition of iu + iv + iw = 0, phase currents (iu, iv, iw) flowing in the shoreline of each phase are obtained from the currents, detected by the current sensors 805a, 805b. Also, the phase applied to the winding of each phase from the three-phase duty values Du, Dv, Dw output by the sine wave voltage output means 809 and the power supply voltage Vdc obtained from the voltage dividing resistors 813a, 813b. The voltage (vu, vv, vw) is obtained from the following equation.

 vu = Du XVdc ... (Formula 12)

w = DvXVdc ... (Formula 13) vw = DwXVdc- (Equation 14)

[0076] From these values, the induced voltage values eu, ev, and ew induced in the shoreline of each phase are obtained by the following calculations (Equation 15), (Equation 16), and (Equation 17).

 eu = vu— R'iu— L'dUu) / dt '· · (Equation 15)

 ev = w— R'iv— L'd (iv) / dt '· · (Equation 16)

 ew = vw— R'iw— L'd (iw) / dt '· (Equation 17)

[0077] Here, R is the resistance of the winding, and L is the inductance of the winding. D (iu) / dt, d (iv)

/ dt and d (iw) Zdt are time derivatives of iu, iv and iw, respectively.

Next, the rotor position Θ and the estimated rotational speed com are estimated from the obtained induced voltage values eu, ev, and ew. This is a method of estimating the rotor position Θ by converging it to a true value by correcting the estimated angle Θm recognized by the variable speed converter 508 using the error of the induced voltage. In addition, the estimated rotational speed com is also estimated from the estimated angle Θm.

First, an induced voltage reference value (eum, evm, ewm) of each phase is obtained by the following formula.

 eum = em'sin, Θ m + β (Equation 18)

 evm = em-sin (Θ m + β -120 °) (Equation 19)

 ewm = em-sin (Θ m + β -240 °)… (Formula 20)

 Here, the induced voltage amplitude value em is obtained by matching the amplitude values of the induced voltage values eu, ev, and ew.

 A deviation ε between the induced voltage value thus obtained and the induced voltage reference value is created. In other words, the deviation ε is obtained by subtracting the induced voltage reference value es m of each phase from the estimated induced value es of each phase as shown in (Equation 21) below.

 ε = es— esm '· · (Formula 21J

 Where s is the phase (u / v / w).

 [0081] When the deviation ε force becomes zero, the estimated angle Θ m becomes a true value. Therefore, the true value of the estimated angle Θ m is obtained as the rotor position Θ (estimated magnetic pole position) by, for example, a method of converging the deviation ε by the ΡΙ operation so that the deviation ε converges to zero. Further, the estimated rotational speed com can be estimated by calculating the fluctuation value of the estimated angle Θ m.

It should be noted that the rotor element Θ may be detected by a resolver to obtain the rotational speed ω. Of course it is good.

[0083] 8. Control when regenerative power exceeds power consumption

 As described above, in normal operation, the power consumption Wm of the motor 505 is larger than the regenerative power Wg from the generator 507. However, when the heat pump application device 500 is started, stopped, when the compressor decelerates, or when the heat exchange state changes suddenly, (power consumption Wm) <(regenerative power Wg) may occur. If this situation continues, the DC power lines DL and DL

 1 2 The voltage may rise excessively, which may cause damage to the electrical components such as the smoothing capacitor 512. Therefore, excessive voltage rise of the DC power lines DL and DL is prevented as follows.

 1 2

 [0084] As mentioned in FIG. 6, permanent magnet synchronous motors such as SPMSM and IPMSM have a current phase angle j8 that can maximize the generated torque for the same current. Conversely, by avoiding the current phase angle β where the generated torque is maximized, it is possible to perform an intentionally inefficient operation without changing the rotational speed.

 FIG. 9 is a characteristic diagram showing loss characteristics of a permanent magnet synchronous generator (IPMSM) of a certain design. In other words, it is a characteristic diagram showing the loss characteristic of the generator with respect to the magnitude of the d-axis current that is the excitation direction of the permanent magnet synchronous generator. As shown in this figure, the loss of the generator varies with the d-axis current, and there is a d-axis current value Id that minimizes the loss. Opt

 Therefore, during normal operation, the d-axis current Id should be controlled opt to minimize the generator loss. On the other hand, if the d-axis current is deviated from the optimum value Id, the generator efficiency decreases.

 I understand that In addition, increasing the d-axis current (increasing the absolute value of the d-axis current) decreases the field, and the induced voltage value decreases.

 [0086] Therefore, in order to reduce the voltage of the DC power lines DL, DL,

 1 2

 If the d-axis current is shifted from the optimum value Id to reduce power generation efficiency and reduce the amount of regenerative power, opt

 In addition, the induced voltage value may be lowered by the field weakening effect. For example, DC power line

The DL and DL voltages are the reference values (for example, when full-wave rectification is applied to a 200V AC power input)

1 2

, Approximately 280V), if the range of + 20V that does not affect the electrical components such as capacitors is exceeded (that is, the threshold voltage is exceeded), the current phase angle is shifted from the optimum value. Execute control. In this way, the d-axis current is changed to lower the power generation efficiency, and the voltage of the DC power lines DL and DL is reduced by the field weakening effect. However, As can be seen from Fig. 9, even when the d-axis current is changed in the direction of increasing the field, a decrease in power generation efficiency can be expected.

Specifically, the variable speed converter 508 detects the voltage of the DC power lines DL and DL by the first voltage detection sensor 520, and when the voltage value exceeds a predetermined value, the electric power of the generator 507 is detected.

1 2

 Control is performed to shift the flow phase angle β from the optimum value Id. Figure 10 shows the microcomputer 508b opt

 This is a flow chart of the current phase angle determination program (current phase angle determination means 815) executed in step 1.

 First, the microcomputer 508b samples the voltage V of the DC power lines DL and DL from the first voltage detection sensor 520 (ST1). Next, DC power line DL, DL

1 2 DL 1 2 Determine whether voltage V is lower than threshold voltage V (ST2). If the threshold voltage is less than V

DL TH TH

 If it is determined, the optimum current phase angle β is obtained so that the power generation efficiency is maximized, and the current opt

 Pass to command creation means 811 (current command creation program) (ST3). In the case of SPMSM, β = 0 ° is determined. In the case of IPMSM, as mentioned above, the current command value I * is opt

 Depending on the optimum current phase angle 13

 You will find opt.

 [0089] On the other hand, if it is determined that the voltage V of the DC power lines DL and DL is equal to or higher than the threshold voltage V,

 1 2 DL TH

 The difference between the voltage V of the current DC power lines DL and DL and the threshold voltage V (V

 1 2 DL TH DL

-V), and calculate the amount of phase angle deviation Δ | 8 according to the deviation (V -V).

TH DL TH

 (ST4). Specifically, the phase angle deviation Δ | 8 should be proportional to (V -V).

 DL TH

 (See Fig. 11). After calculating the phase angle deviation amount Δ β, the optimum current phase angle value β is obtained, and the current phase angle 13 opt opt obtained by adding or subtracting the phase angle deviation amount Δ β to 13

 'Is calculated (ST5). Then, the calculated current phase angle β ′ is passed to the current command creating means 811 (ST6).

 [0090] Whether to make β '= β Δ j8 or β' = β + Δ j8 depends on the specifications of the generator 507 opt opt

 Can be determined. The current phase angle j8 ′ can be determined in the range of 0 ° to 90 ° so that the generator 507 can be appropriately controlled. Also, the current phase angle β with respect to (V -V)

It is not essential to change to DL 力, force S linear. In short, it is sufficient if the generator 507 changes from a high efficiency state with high power generation efficiency to a low efficiency state with low power generation efficiency. In an extreme case, the current phase angle / 3 passed to the current command creation means 811 may be one. [0091] For example, when the condition of (V <V) is satisfied, it is optimum to maximize the power generation efficiency

DL TH

 The generator 507 is controlled in the first mode that adopts a current phase angle j8, and (V <V)

 DL TH

 When the condition is not satisfied, the generator 507 is controlled in the second mode that employs the current phase angle β ′, in which the power generation efficiency is lower than that in the first mode. In this way, it is possible to perform simple control with a very small load on the microphone computer 508b. For example, in SPMSM, it can be fixed at an arbitrary value of j8, ≠ 0 °. In IPMSM, for example, β, = 0 ° can be fixed.

FIG. 11 is a characteristic diagram showing the setting principle of the current phase angle of the variable speed converter 508 in the heat pump application device 500 of the present embodiment. DC power line DL, DL voltage V

 1 2 When D is less than 280V (reference value) + 20V = 300V (threshold voltage V), the generator 507

 The current phase angle is set to the optimum value j8 that maximizes the power generation efficiency. Voltage V Force S300V (Threshold opt DL

 Value voltage V) or more, make the current phase angle larger than its optimum value | 8 or

 TH opt

 Set smaller. That is, the voltage V of the DC power lines DL and DL exceeds the threshold voltage V.

 1 2 DL TH Therefore, it is possible to reduce the voltage without reducing the rotation speed due to the decrease in power generation efficiency and the field weakening effect.

V goes down. In this way, the variable speed converter 508 allows the generator 507 and the expander to

DL

 While optimally controlling the number of revolutions of the 503, the voltage V of the DC power lines DL and DL is adjusted to the threshold voltage.

 1 2 DL Pressure can be kept below V. That is, the variable speed converter 508

TH

 A voltage suppressor that suppresses the voltage V of Karin DL and DL to less than the specified value (threshold voltage V).

 1 2 DL TH

 Functions as a stage.

 [0093] In the case of IPMSM, if too much negative d-axis current is applied, the magnet may be irreversibly demagnetized due to the demagnetizing magnetomotive force, and attention must be paid to the maximum value of I Id I. Is. However, since β = 0 ° is a condition that maximizes the magnet torque, it may not be possible to expect a significant reduction in efficiency. Therefore, it is possible to execute control to shift the current phase angle β in the direction in which I id I increases (the direction in which the field weakening effect increases) within a range where irreversible demagnetization does not occur.

 [0094] Further, it is possible to cause the inverter 506 to execute the same control as described above. That is, the inverter 506 detects the voltage V of the DC power lines D L and DL by the second voltage detection sensor 521, and if the voltage value exceeds a predetermined value, the current of the motor 505

1 2 DL The voltage of the DC power lines DL and DL is reduced by shifting the phase angle to the optimum value and reducing the driving efficiency.

 2

 Reduce V and perform control so that it falls within the specified range.

 DL

 [0095] The setting principle of the current phase angle of the inverter 506 in the present embodiment may be exactly the same as in FIG. In other words, DC power line DL, DL voltage V force S280V (reference value) + 20V = 3

 1 2 DL

 If it is less than OOV (threshold voltage V), the motor 505 current phase angle is the maximum drive efficiency.

 TH

 Set to an optimal value. When the voltage V becomes 300V (threshold voltage V) or more,

 DL TH

 The current phase angle is set larger or smaller than the optimum value. DC power line DL, D

 1

When the voltage V of L exceeds the threshold voltage V, the driving efficiency of the motor 505 decreases. Driving effect

2 DL TH

 When the rate decreases, the power consumption increases without increasing the rotational speed. In this way, it is possible to keep the voltage V of the DC power lines DL and DL below the threshold voltage V while optimally controlling the rotation speeds of the motor 505 and the compressor 501 by the inverter 506.

 1 2 DL TH

 That is, the inverter 506 sets the voltage V of the DC power lines DL and DL to a predetermined value (threshold voltage).

 1 2 DL

 Pressure V)

 Functions as a voltage suppression means that suppresses below TH.

 Of course, the control for reducing the power generation efficiency of the generator 507 and the control for reducing the driving efficiency of the motor 505 may be executed in parallel. In that case, the DC power line DL,

 1

It can cope with a sudden rise in DL voltage V, and the d-axis current can be changed dramatically.

 2 DL

 Even without this, the effect of reducing the voltage V of the DC power lines DL and DL can be obtained sufficiently.

 1 2 DL

 It becomes possible.

[0097] (Second Embodiment)

 FIG. 12 is a block diagram showing a heat pump application device according to the second embodiment of the present invention. The same reference numerals are used for parts common to the first embodiment. The configuration of the heat pump application device 550 of the second embodiment is the same as the configuration of the heat pump application device 500 of the first embodiment in that a set of the switch 513 and the load 514 is connected in parallel to the DC power line DL.

1

 Is different. The heat pump application device 550 also detects the microcomputer 519 as a control means for controlling on / off of the switch 513 and the voltage V of the DC power lines DL and DL.

 1 2 DL A third voltage detection sensor 522 for outputting. The detection result by the third voltage detection sensor 522 is input to the microcomputer 519.

[0098] The switch 513 may be a semiconductor switch such as a transistor or a machine such as a relay. It may be a typical switch. The type of load 514 is not limited as long as it is a resistive load that can consume DC power, but a simple resistance is desirable from the viewpoint of cost. Note that the switch 513 and the load 514 may be arranged in the DC power line DL on the variable speed converter 508 side.

 2

 [0099] The combination of the switch 513 and the load 514 connected in series is the voltage of the DC power lines DL and DL.

 1 2

When V exceeds the threshold voltage V, the power supplied to the DC power lines DL and DL

DL TH 1 2

 The power consumption starts and the voltage V of the DC power lines DL and DL is set to the predetermined value (threshold voltage V).

 1 2 Functions as voltage suppression means 515 that suppresses to less than DL TH. Switch 513 and load 514 operate as follows.

 FIG. 13 is a characteristic diagram showing the transition of the voltage V of the DC power lines DL and DL. 3rd electric

 1 2 DL

 The voltage V of the DC power lines DL and DL detected by the pressure detection sensor 522 is a predetermined value.

 1 2 DL The microcomputer 519 turns on the switch 513 when the DL control start voltage, for example, 320 V or more is reached. From this, the DC power line DL and DL force also flows through the load 514.

 1 2

 The As the load 514 consumes power, the voltage V of the DC power lines DL and DL is low.

 1 2 DL Move down. After that, the voltage V of the DC power lines DL and DL becomes a predetermined control end voltage, for example

 1 2 DL

 If the voltage drops below 310V, the microcomputer 519 turns off the switch 513. As described above, the third voltage detection sensor 522, the microcomputer 519, the switch 513, and the load 514 perform control to keep the voltage V of the DC power lines DL and DL within a predetermined range.

 1 2 DL

 Is done.

 [0101] After such control is repeated, if the operating status of the heat pump application device 550 changes and the power consumption Wm of the motor 505 is greater than the regenerative power Wg, the DC power lines DL and DL

 The voltage V of 1 stabilizes at a steady value. In this way, the voltage of the DC power lines DL and DL

2 DL 1 2 Overheating is avoided, and electrical components such as capacitors are not destroyed. A highly reliable heat pump application device can be realized.

 [0102] Note that the switch 513, the load 514, the third voltage detection sensor 522, and the microcomputer 519 may be configured as a part of the power recovery apparatus 601 described in the first embodiment.

[0103] In addition, the load 514 can be replaced with a capacitor such as a capacitor having a power storage function. Noh. That is, the voltage V of the DC power lines DL and DL is not less than the threshold voltage V.

 1 2 When DL TH is connected, switch 513 is turned on to start storing power in the battery. Even with such a configuration, it is possible to suppress the voltage increase of the DC power lines DL and DL.

 1 2

 [0104] Further, the control (first embodiment) for reducing the power generation efficiency of the generator 507 and the drive efficiency of the motor 505 by controlling the current phase angle β is executed in parallel with the control of the second embodiment. May be. Then, the voltage V of the DC power lines DL and DL rises rapidly.

 1 2 DL

 It will be possible to respond quickly to cases.

[0105] (Third embodiment)

 FIG. 14 is a block diagram showing a heat pump application device according to a third embodiment of the present invention. The heat pump application device 560 includes a power recovery device 602 including an expander 503, a generator 507, and a variable speed converter 528. These points are the same as in the first embodiment. The difference from the first embodiment is that the voltage V of the DC power lines DL and DL is the threshold value.

 1 2 Variable speed converter 528 and inverter 526 execute when DL voltage becomes V or higher.

ΤΗ

 Is in control.

 [0106] When the voltage V of the DC power lines DL and DL exceeds the threshold voltage V, the variable speed control

 1 2 DL ΤΗ

 The barter 528 performs control to reduce the rotational speed of the generator 507 and the expander 503, and suppresses the voltage V of the DC power lines DL and DL to be less than the threshold voltage V. Similarly, Imba

 1 2 DL ΤΗ

 The data 526 executes control to increase the rotational speeds of the motor 505 and the compressor 501 and suppress the voltage V of the DC power lines DL and DL to be less than the threshold voltage V.

 1 2 DL ΤΗ

 FIG. 15 is a characteristic diagram showing the transition of the voltage V of the DC power lines DL and DL. Normal condition

 1 2 DL

 In this state, the rotation speeds of the expander 503 and the compressor 501 are controlled to the optimum values so that the output of the heat pump application device 560 is set to a desired value and the refrigeration cycle efficiency is maximized.

 On the other hand, the voltage V of the DC power lines DL and DL is a predetermined control start voltage (threshold voltage V).

 1 2 DL ΤΗ

For example, when it becomes 320 V or more, variable speed converter 528 executes control to reduce the rotational speeds of generator 507 and expander 5003. As a result, the amount of power generated by the expander 503 decreases, and the voltage V of the DC power lines DL and DL decreases. Then, DC power line DL

 1 2 DL 1

, When the DL voltage V drops below a certain control end voltage, e.g. 310V, the variable speed co

2 DL The inverter 528 again sets the rotation speeds of the generator 507 and the expander 503 to a predetermined rotation speed that maximizes the refrigeration cycle efficiency. After such control is repeated, if the operating status of the heat pump application device 550 changes and the power consumption Wm of the motor 505 is greater than the regenerative power Wg from the variable speed converter 528, the DC power line DL, DL voltage V

 1 2

 DL stabilizes to a steady value.

 [0109] As described in the first embodiment, the target rotational speed of the generator 507 has the maximum refrigeration cycle efficiency based on the outputs of the temperature sensor 516 and the pressure sensor 517 arranged at the outlet of the radiator. The microcomputer 509 decides so that Therefore, the microcomputer 509 can acquire the output of the first voltage detection sensor 520, and the microcomputer 509 determines whether or not the voltage V of the DC power lines DL and DL is excessive.

 1 2 DL

 You may make it refuse. Microcomputer 509 is a DC power line DL, DL

 1 2 Target that maximizes refrigeration cycle efficiency when voltage V exceeds threshold voltage V

DL TH

 Set the number of revolutions lower than the number of revolutions. Then, the set rotational speed is passed to the variable speed converter 528. Of course, whether the voltage V of the DC power lines DL and DL is higher than the threshold voltage V

 1 2 DL TH

 The key may be determined by the variable speed converter 528. In this case, the variable speed converter 528 performs the calculation of (Equation 2) at a lower rotational speed than the target rotational speed passed from the microcomputer 509.

[0110] Further, the rotational speed of the compressor 506 may be changed. DC power line DL, DL

 1 When the voltage V of 2 becomes a predetermined control start voltage (threshold voltage V), for example, 320 V or higher, the

 DL TH

 The barter 526 executes control for increasing the rotational speeds of the motor 505 and the compressor 501. As a result, the power consumption of the motor 505 increases and the voltage V of the DC power lines DL and DL is reduced.

 1 2 DL Decreases. After that, the voltage V of the DC power lines DL and DL is the predetermined control end voltage, eg

 1 2 DL

 For example, when the voltage drops below 310 V, inverter 526 resets the rotation speeds of motor 505 and compressor 501 to a predetermined rotation speed that maximizes the refrigeration cycle efficiency.

[0111] By the control as described above, the voltage increase of the DC power lines DL and DL is avoided, and as a result

 1 2

Can realize a highly reliable heat pump application device with little risk of destruction of electrical components such as capacitors. In the present embodiment, the configuration in which the number of revolutions of the generator 507 is manipulated has been described. For example, a similar function can be realized with a configuration in which the current value is increased. That is, in this embodiment, there is also a method in which the current control loop is incorporated in the rotation speed control loop and the control is performed by removing the rotation speed control loop and giving the command current value as the target value. In this case, the torque (= current) is controlled rather than controlling the rotational speed of the expander 503. If it is such control, an induction motor can be used suitably besides a synchronous motor (synchronous generator).

[0112] Finally, it should be noted that several embodiments described in this specification can be combined with each other without departing from the spirit of the present invention.

 Industrial applicability

[0113] As described above, the heat pump application device and the power recovery device of the present invention have the effect of improving reliability without destruction of the component parts, and are useful for heat pump refrigeration devices such as air conditioning and heating devices and water heaters. is there.

Claims

The scope of the claims

 [1] a compressor for compressing the refrigerant;

 A motor for operating the compressor;

 A radiator for cooling the refrigerant compressed by the compressor;

 An expander that expands the refrigerant that has passed through the radiator;

 An evaporator for evaporating the refrigerant expanded by the expander;

 A generator connected to the expander and generating power with the expansion energy of the refrigerant; DC power output means for converting AC power generated by the generator into DC power and regenerating and outputting the DC power;

 Voltage suppression means for suppressing the voltage of the DC power line, in which the DC power output means regenerates power, to less than a predetermined value;

 Heat pump application equipment equipped with.

[2] The heat pump application device according to [1], wherein the voltage suppression means is also used as a generator control means for controlling driving of the generator.

[3] The heat pump application device according to claim 2, wherein the generator control means executes control for reducing the power generation efficiency of the generator when the voltage of the DC power line becomes equal to or higher than the predetermined value. .

[4] The generator is a permanent magnet type synchronous generator,

 And a variable speed converter including both the DC power output means and the generator control means,

 The variable speed converter performs control to change the current phase angle of the permanent magnet type synchronous generator so that the permanent magnet type synchronous generator moves from a high efficiency state with high power generation efficiency to a low efficiency state with low power generation efficiency. The heat pump application apparatus according to claim 3, wherein the heat pump application apparatus is executed.

 5. The heat pump application device according to claim 1, wherein the voltage suppression unit is also used as a motor control unit that controls driving of the motor.

6. The heat pump application device according to claim 5, wherein the motor control means executes control for reducing drive efficiency of the motor when the voltage of the DC power line becomes equal to or higher than the predetermined value.

[7] The motor is a permanent magnet type synchronous motor,

 The motor control means is an inverter that executes control for changing a current phase angle of the permanent magnet type synchronous motor to change the permanent magnet type synchronous motor from a high efficiency driving state to a low efficiency driving state. Item 6. Heat pump application device.

[8] The voltage suppression means starts storing or consuming power supplied to the DC power line when the voltage of the DC power line becomes equal to or higher than the predetermined value.

1. Heat pump application equipment described in 1.

[9] The voltage suppression means includes a load and a switch for turning on and off the power supply to the load, and turns on the switch when the voltage of the DC power line becomes equal to or higher than the predetermined value. 9. The heat pump application device according to claim 8, wherein power supply to the load is started.

10. The heat pump application device according to claim 2, wherein the generator control means executes control to reduce the number of revolutions of the generator when the voltage of the DC power line becomes equal to or higher than the predetermined value. .

 11. The heat pump application device according to claim 5, wherein the motor control means executes control to increase the number of rotations of the motor when the voltage of the DC power line becomes equal to or higher than the predetermined value.

 [12] an expander for expanding the working fluid;

 A generator that is connected to the expander and generates power with the expansion energy of the working fluid; and a DC power output means that converts AC power generated by the generator into DC power and outputs the DC power.

 Generator control means for executing control to reduce the power generation efficiency of the generator when the output voltage of the DC power output means is a predetermined value or more;

 Power recovery device with

13. The power recovery apparatus according to claim 12, comprising a variable speed comparator including both the DC power output means and the generator control means.

[14] The generator is a permanent magnet type synchronous generator,

The variable speed converter is arranged so that the permanent magnet synchronous generator moves from a high efficiency state with high power generation efficiency to a low efficiency state with low power generation efficiency. 14. The power recovery apparatus according to claim 13, wherein control for changing a current phase angle is executed.

[15] an expander for expanding the working fluid;

 A generator that is connected to the expander and generates power with the expansion energy of the working fluid; and a DC power output means that converts AC power generated by the generator into DC power and outputs the DC power.

 A power recovery apparatus, comprising: a voltage suppression unit that receives power supply from the DC power output unit and starts power storage or power consumption when an output voltage of the DC power output unit exceeds a predetermined value.

[16] The voltage suppression means includes a load and a switch for turning on and off the power supply to the load, and turns on the switch when the output voltage of the DC power output means becomes equal to or higher than the predetermined value. 16. The power recovery apparatus according to claim 15, wherein power supply to the load is started from the DC power output means.

[17] an expander for expanding the working fluid;

 A generator that is connected to the expander and generates power with the expansion energy of the working fluid; and a DC power output means that converts AC power generated by the generator into DC power and outputs the DC power.

 Generator control means for executing control to reduce the rotational speed of the generator when the output voltage of the DC power output means is equal to or higher than a predetermined value;

 Power recovery device with