Electric power conversion device and heat pump system

Abstract

To supply a current suitable for a capacity of a power distribution facility and / or a distribution line from a power conversion device as compared with the case where a current is supplied from the power conversion device to the distribution line irrespective of a maximum value of a received current of an inverter device.SOLUTION: A power conversion device is a power conversion device connected to a power receiving point of an inverter device that receives a power from a power distribution facility via a distribution line, and includes: a supply circuit that supplies a harmonic current to the power receiving point and supplies a fundamental reactive current to the power distribution facility via the distribution line; and a control unit that controls a current supplied by the supply circuit. The control unit acquires the received current of the inverter device, and limits the fundamental reactive current by using the first current limit value set by a maximum value of the received current of the inverter device and the received current of the inverter device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion device and a heat pump system. [Background technology]

[0002] Patent Document 1 discloses an active filter device connected to a power conversion device that receives power via a distribution board, the active filter device comprising: a current source whose output is connected to the power receiving path of the power conversion device and capable of generating a first compensating current for at least one of reducing harmonic currents in the power conversion device and improving the fundamental power factor; a first detection unit that detects the current flowing in the power receiving path of the power conversion device; a second detection unit that detects the current flowing in the power receiving path of the distribution board; and a controller that calculates the first compensating current based on the detection value detected by the first detection unit, calculates a second compensating current based on the detection value detected by the second detection unit for at least one of reducing harmonic currents in the power receiving path of the distribution board and improving the fundamental power factor, and generates a current in which the second compensating current and the first compensating current are superimposed in the current source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-057201 Summary of the Invention [Problem to be solved by the invention]

[0004] A power conversion device connected to a power receiving point of an inverter device that receives power from a power distribution facility via a distribution line may supply a compensation current to the power distribution facility via the distribution line. For example, if the maximum received current of the inverter device is small, and the power conversion device supplies current up to the maximum supply current, power exceeding the capacity of the power distribution facility and / or the distribution line may be supplied. The present disclosure aims to have a power conversion device supply a current that is appropriate for the capacity of the distribution equipment and / or the distribution line, compared to when the power conversion device supplies current to the distribution line regardless of the maximum value of the receiving current of the inverter device. [Means for solving the problem]

[0005] A power conversion device according to the present disclosure is connected to a power receiving point of an inverter device that receives power from a power distribution facility via a distribution line, and includes: a supply circuit that supplies harmonic current to the power receiving point and a fundamental reactive current to the power distribution facility via the distribution line; and a control unit that controls the current supplied by the supply circuit, wherein the control unit acquires the received current of the inverter device and limits the fundamental reactive current using a first current limit value that is set based on the maximum received current of the inverter device and the received current of the inverter device. In this case, the power conversion device can supply a current that is appropriate for the capacity of the power distribution facility and / or the distribution line, compared to when the power conversion device supplies a current to the distribution line regardless of the maximum received current of the inverter device. The control unit acquires a fundamental current of the received current of the inverter device and varies the first current limit value in accordance with a change or amount of change in the fundamental current. In this case, a larger fundamental current can be supplied from the power conversion device than when the first current limit value is determined from the received current. The control unit also acquires capability information relating to the power receiving capacity of the inverter device or the equipment equipped with the load driven by the inverter device, and determines the maximum receiving current value from the acquired capability information. In this case, a current appropriate for the capacity of the power distribution facility and / or the power line can be supplied from the power conversion device, compared to a case in which the first current limit value is not determined based on the capability information relating to the power receiving capacity of the equipment. Furthermore, the control unit limits the fundamental reactive current using the smaller of the first current limit value and a second current limit value set based on the maximum supply current of the power conversion device and the harmonic current supplied to the power receiving point. In this case, power supply exceeding the supply capacity of the power conversion device can be suppressed. The control unit also varies the maximum supply current value in accordance with a change or amount of change in the received current of the inverter device, thereby suppressing an increase in loss and a temperature rise of the switching elements compared to when the maximum supply current value is not varied. In addition, the supply circuit has a plurality of switching elements, and the switching elements include wide bandgap semiconductor elements. In this case, loss in the switching elements can be reduced compared to when wide bandgap semiconductors are not used for the plurality of switching elements. Furthermore, the power conversion device is provided in a heat pump system including a compressor to which power generated by the inverter device is supplied. In this case, the heat pump system can supply a current suitable for the capacity of the power distribution facility and / or the power distribution line, compared to a case in which the power conversion device supplies a current to the power distribution line regardless of the maximum current received by the inverter device. Furthermore, the power conversion device of the present disclosure is connected to the power receiving points of a plurality of the inverter devices, and the first current limit value is set based on the combined maximum receiving current value of the plurality of inverter devices and the combined receiving current of the plurality of inverter devices. In this case, even when a plurality of inverter devices are mounted on an equipment, the power conversion device can supply a current appropriate for the capacity of the power distribution facility and / or the power distribution line, compared to when a current is supplied from the power conversion device to the power distribution line regardless of the maximum receiving current value of the inverter devices. Furthermore, a heat pump system according to the present disclosure includes the power conversion device according to claim 1 or 2 and the inverter device. In this case, the power conversion device can supply a current suitable for the capacity of the power distribution facility and / or the power distribution line, compared to when the power conversion device supplies a current to the power distribution line regardless of the maximum value of the received current of the inverter device. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a diagram showing an example of the configuration of a customer facility in which an active filter device according to an embodiment of the present invention is used. [Figure 2] 1 is a diagram showing an example of the configuration of an air conditioning apparatus according to an embodiment of the present invention; [Figure 3] FIG. 2 is a diagram illustrating a configuration example of a fundamental wave reactive current command generating unit according to the present embodiment. [Figure 4] 10 is a diagram showing an example of the relationship between the power consumption of an air conditioner including an active filter device according to the present embodiment and a first current limit value and a second current limit value. FIG. [Figure 5] FIG. 10 is a diagram showing an example of the configuration of an air conditioner in which an active filter device is connected to the power receiving points of two inverter devices. [Figure 6] FIG. 1(a) is a diagram showing an example of the relationship between the power consumption of an air conditioning device equipped with an active filter device and the compensation current supplied by the active filter device, and FIG. 1(b) is a diagram showing an example of the relationship between the power consumption of an air conditioning device equipped with an active filter device and the loss in the switching element of the active filter device. [Figure 7] FIG. 10 is a diagram illustrating a configuration example of a fundamental wave reactive current command generating unit of an active filter device according to a modified example. [Figure 8] FIG. 10 is a diagram showing the relationship between the load current and the maximum supply current value according to the modified example. [Figure 9] FIG. 10(a) is a diagram showing the relationship between the power consumption of an air conditioning device equipped with an active filter device according to a modified example and the compensation current supplied by the active filter device, and FIG. 10(b) is a diagram showing the relationship between the power consumption of an air conditioning device equipped with an active filter device according to a modified example and the loss in the switching element of the active filter device. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. <Configuration of consumer facilities> Fig. 1 is a diagram showing an example of the configuration of a customer facility 10 in which an active filter device 100 according to this embodiment is used. Fig. 1 shows a case in which an air conditioning device 36 installed in the customer facility 10 is equipped with the active filter device 100. The active filter device 100 is an example of a power conversion device. The air conditioning device 36 is also an example of a heat pump system. The active filter device 100 may not be incorporated into the air conditioner 36 but may be provided outside the air conditioner 36.

[0008] The customer facility 10 is, for example, a building, a factory, an apartment building, etc. Electric power is supplied to the customer facility 10 from a power source 20 via a power distribution line 21. Here, the power source 20 and the power distribution line 21 are collectively referred to as a power distribution system. The power distribution line 21 has a power distribution line impedance 22 (see FIG. 2 ). The power source 20 is, for example, a three-phase AC power source (commercial power source). The power source 20 is an example of a power distribution facility.

[0009] Customer facility 10 includes a distribution transformer 11, a distribution board 12, and an air conditioner 36. Air conditioner 36 is an example of an electrical device (hereinafter referred to as "device") that receives power from power source 20 via distribution line 21. Distribution transformer 11 converts the voltage received from power source 20 and sends it to distribution board 12. Examples of distribution transformers 11 include a transformer that converts a voltage of 6600V to 200V, and a transformer that converts a voltage of 6600V to 100V. The distribution board 12 transmits the electricity received from the distribution transformer 11 to the equipment. The distribution board 12 is equipped with an earth leakage breaker 13 and a distribution circuit breaker 14. The earth leakage breaker 13 prevents electric shock by interrupting the circuit when it detects a ground fault. The distribution circuit breaker 14 interrupts the circuit when an abnormal current flows in the distribution line, protecting the distribution line, equipment, etc. The distribution transformer 11 and the distribution board 12 are examples of power distribution equipment.

[0010] The air conditioner 36 includes a refrigerant circuit (not shown) in which a refrigerant circulates to perform a refrigeration cycle operation, and performs indoor cooling and heating in a building, etc. The refrigerant circuit of the air conditioner includes a compressor that compresses the refrigerant. The air conditioner 36 includes an inverter device 60, a motor 65, and an active filter device 100.

[0011] FIG. 2 is a diagram showing an example of the configuration of an air conditioning device 36 according to this embodiment. The air conditioning device 36 includes an inverter device 60, a motor 65, and an active filter device 100. Below, an overview of the inverter device 60 and the motor 65 will be given, and the active filter device 100 will be given in detail.

[0012] As shown in FIG. 2, the inverter device 60 includes a converter circuit 61, a reactor 62, a capacitor 63, an inverter circuit 64, and an inverter control unit 66. The converter circuit 61 is a circuit that converts AC to DC. The converter circuit 61 is, for example, a diode bridge circuit. The capacitor 63 smoothes the output of the converter circuit 61. The inverter circuit 64 converts the DC smoothed by the capacitor 63 into AC of a predetermined frequency and a predetermined voltage. The inverter circuit 64 includes, for example, a plurality of (six in this example) bridge-connected switching elements, and converts the input DC into AC by switching it. That is, the inverter circuit 64 changes the switching states (on / off states) of the plurality of switching elements in synchronization with a drive signal of a predetermined frequency output by the inverter control unit 66.

[0013] The motor 65 is, for example, an interior permanent magnet motor (IPM motor). The motor 65 drives a compressor provided in the refrigerant circuit. If no special measures are taken, the operation of the motor 65 will result in a current (hereinafter referred to as system current (I S )) and harmonic currents are added to the inverter device 60. That is, the inverter device 60 is an example of a load and an example of a device that generates harmonic currents.

[0014] <Configuration of active filter device> If the load includes an inverter circuit, the inverter circuit is a diode bridge circuit, and when it converts AC to DC, harmonic currents are added to the current in the power distribution system, affecting the power supply 20. Therefore, the active filter device 100 suppresses the harmonic currents by passing a compensation current through the power distribution system. Moreover, the active filter device 100 described in this embodiment has a function of adjusting the voltage of the power distribution system, and is configured to output a compensation current for the fundamental wave current in addition to the harmonic current. The fundamental wave is a sine wave made up of frequency components of the power supply 20. For example, if the frequency of the power supply is 50 Hz, the frequency of the fundamental wave will be 50 Hz. Furthermore, harmonics are frequency components that are integer multiples (twice or more) of the fundamental wave. The fundamental wave is not included in harmonics. In this disclosure, the fundamental wave component of a current is referred to as a fundamental wave current, and the harmonic wave component of a current is referred to as a harmonic current.

[0015] 2 includes a current source 110 and a control unit 120. The active filter device 100 is connected to a power source 20 in parallel with an inverter device 60. The active filter device 100 generates a compensation current (I AF ) to the power distribution system, the power factor of the fundamental wave is improved and the harmonic current from the inverter device 60 in the air conditioner 36 is suppressed. AF ) is positive when it flows from the current source 110 to the power distribution system. S ) and compensation current (I AF ) is the load current (I INV ).

[0016] The current source 110 includes an inverter circuit 111, a capacitor 113, and a reactor 146. The capacitor 113 is, for example, an electrolytic capacitor. The inverter circuit 111 charges and discharges the capacitor 113 to generate a compensation current (IAF ) is input and output. In this example, the inverter circuit 111 is connected to a power distribution system via a three-phase reactor 146. Like the inverter circuit 64, the inverter circuit 111 is configured with a plurality of (six in this case) bridge-connected switching elements 112. The switching elements 112 are configured to include, for example, wide bandgap semiconductors. In this case, loss in the switching elements 112 can be reduced compared to when wide bandgap semiconductors are not used.

[0017] The inverter circuit 111 changes the switching states (on / off states) of the multiple switching elements 112 in synchronization with the drive signal G of a predetermined frequency output by the drive signal generation unit 141, and generates a compensation current (I AF ) is input and output. In Figure 2, the compensation current (I AF A low-pass filter 145 that removes ripples from the current is provided between the reactor 146 and the connection point between the power distribution system and the inverter device 60. The low-pass filter 145 is a so-called LC filter. The current source 110 is an example of a supply circuit.

[0018] The control unit 120 includes a zero-cross signal detection circuit 121, a power supply phase calculation unit 122, an INV current detection circuit 123, a compensation current detection circuit 124, two dq converters 125 and 126, a harmonic detection unit 127, two adders 128 and 137, three subtractors 129, 131, and 138, a DC voltage control unit 130, a d-axis current controller 132, a DC voltage detection circuit 133, an AF harmonic current calculation unit 134, a q-axis current controller 139, a fundamental reactive current command generation unit 140, and a drive signal generation unit 141. Specifically, the main parts of the control unit 120 can be configured using a microcomputer, a memory device storing software for operating the microcomputer, and the like.

[0019] The zero-cross signal detection circuit 121 is connected to predetermined lines (any two of the r-phase, s-phase, and t-phase) of the power distribution system, detects the phase of the line voltage, and outputs the result to the power supply phase calculation unit 122. The power supply phase calculation unit 122 uses the signal (called the zero-cross signal (S1)) output by the zero-cross signal detection circuit 121 to determine the phase (ωt) of the power distribution system. The power supply phase calculation unit 122 outputs the determined phase (ωt) to the dq converter 125 and the dq converter 126. The INV current detection circuit 123 detects the load current (I INV The INV current detection circuit 123 detects the three-phase load current (I INV ) of the two-phase load current (i r , i t ) to detect.

[0020] The compensation current detection circuit 124 detects the compensation current (I AF The compensation current detection circuit 124 detects the three-phase compensation current (I AF ) of the load current of two phases. INV ), and compensation current (I AF ) can easily calculate the current value of the remaining phase by detecting the current values ​​of two of the three phases, so the INV current detection circuit 123 and the compensation current detection circuit 124 may be configured to detect currents for two phases. Current sensors of various configurations can be used for the INV current detection circuit 123 and the compensation current detection circuit 124. One example of the INV current detection circuit 123 and the compensation current detection circuit 124 is a current transformer.

[0021] The dq converter 125 converts the load current (I INV ) (three phases), a three-phase / two-phase transformation (dq axis transformation) is performed. Here, the d axis and q axis are a rotating coordinate system that rotates in synchronization with the phase (ωt) calculated by the power supply phase calculation unit 122.

[0022] The d-axis component obtained as a result of the conversion by the dq converter 125 is an active current in the inverter device 60 of the air conditioner 36. The dq converter 125 converts the d-axis component (hereinafter referred to as the d-axis component (i INVd)) to the harmonic detection unit 127. The q-axis component obtained as a result of the conversion by the dq converter 125 is a reactive current in the inverter device 60 of the air conditioner 36. The dq converter 125 converts the q-axis component (hereinafter referred to as the q-axis component (i INVq )) to the harmonic detection unit 127.

[0023] The dq converter 126 converts the compensation current (I AF ) is converted from three-phase to two-phase, and the d-axis component, which is the active current (hereinafter referred to as the d-axis current (i AFd ) and the q-axis component, which is the reactive current (hereafter referred to as the q-axis current (i AFq ) is calculated. AFd ) is output to the subtractor 131 and the AF harmonic current calculation unit 134. In addition, the q-axis current (i AFq ) is output to the subtractor 138 and the AF harmonic current calculation unit 134. The AF harmonic current calculation unit 134 calculates the d-axis current (i AFd ) and q-axis current (i AFq ) and the compensation current (I AF ) harmonic compensation current (I AFh ) is output.

[0024] The harmonic detector 127 detects the load current (I INV ) d-axis component (i INVd ) and outputs it to the adder 128. The output of the dq converter 125 is the load current (I INV If there are no harmonic components in the load current (I INV ) that is synchronized with the phase of the power supply 20 appears as a direct current. INV ) is output to the adder 128. * dh )do. The harmonic detector 127 also detects the load current (I INV ) q-axis component (i INVq ) and output to adder 137 (i* qh )do.

[0025] Compensation current (I AF ) are the d-axis and q-axis components of the load current (I INV ) to match the harmonic components of the compensation current (I AF ) flows, the load current (I INV ) can be cancelled out. Hereinafter, flowing a current so as to cancel out a predetermined component in this way is referred to as compensation. That is, the output from the harmonic detector 127 to the adder 128 is the compensation current (I AF ) d-axis component (d-axis current (i AFd )) command value (d-axis current command value (i * d The output from the harmonic detector 127 to the adder 137 can be used to generate the compensation current (I AF ) q-axis component (q-axis current (i AFq )) command value (q-axis current command value (i * q ) can be used to generate

[0026] In this example, the d-axis current command value (i * d ), the output of the harmonic detector 127 is not used as it is, but the voltage between the terminals of the capacitor 113 (hereinafter referred to as DC voltage (V dc Specifically, the control unit 120 first calculates the DC voltage (V dc ) and its command value (V * dc ) and calculate the deviation from DC voltage (V dc ) is detected by a DC voltage detection circuit 133. The DC voltage control unit 130 performs proportional-integral control (PI control) based on the deviation calculated by the subtractor 129 to obtain a correction value (i * d1 ) is calculated. This correction value (i * d1 ) is added to the output (i * dh) and the sum is the d-axis current command value (i * d ) is output as a DC voltage (V dc The subtractor 131 reduces the influence of fluctuations in the d-axis current (i AFd ) to the d-axis current command value (i * d ) minus the deviation (Δi d ) and calculate the deviation (Δi d ) is output to the d-axis current controller 132.

[0027] The d-axis current controller 132 calculates the deviation (Δi d ) based on the feedback control (for example, so-called PID control) algorithm, the d-axis voltage command value (v * d ) to the drive signal generation unit 141.

[0028] The harmonic detector 127 also detects the load current (I INV ) q-axis component (i INVq ) to obtain the harmonic current command value (i * qh ) to the adder 137. The adder 137 also receives a fundamental reactive current command value (I * q1 ) is input to the fundamental wave reactive current command generating unit 140. The fundamental wave reactive current command value (I * q1 The fundamental wave reactive current command generating unit 140 will be described in detail later. The adder 137 generates the harmonic current command value (i * qh ) and the fundamental reactive current command value (I * q1 ) to obtain the q-axis current command value (i * q ) is output.

[0029] The q-axis current (i AFq ) is output to the subtractor 138. The subtractor 138 outputs the q-axis current command value (i * q ) to the q-axis current (i AFq ) minus the deviation (Δi q ) is input to the q-axis current controller 139. The q-axis current controller 139 calculates the deviation (Δi q ) based on the feedback control (for example, so-called PID control) algorithm, the q-axis voltage command value (v * q ) to the drive signal generation unit 141.

[0030] The drive signal generator 141 generates a d-axis voltage command value (v * d ) and q-axis voltage command value (v * q ) to generate a drive signal (G) for driving the current source 110. The drive signal generating unit 141 performs so-called PWM (pulse width modulation) control to supply a compensation current (I AF The drive signal generating unit 141 can be configured using a microcomputer and a memory device that stores software for operating the microcomputer.

[0031] <Operation of the active filter device 100> The active filter device 100 is incorporated in the air conditioner 36, and the active filter device 100 operates when the air conditioner 36 is energized. In the control unit 120, a dq converter 125 converts the load current (I INV ) d-axis component (i INVd ) and q-axis component (i INVq ) is required.

[0032] q-axis component (i INVq ) is subjected to removal of DC components by the harmonic detector 127, and the harmonic current command value (i * qh ) is output. d-axis component (iINVd ) has its DC component removed by harmonic detector 127 and is output to adder 128. Adder 128 calculates the DC voltage (V dc ) and its command value (V * dc ) and the output (i * dh ) to obtain the d-axis current command value (i * d ) is output.

[0033] In addition, the dq converter 126 generates a compensation current (I AF ) d-axis current (i AFd ) and q-axis current (i AFq ) is obtained by the subtractor 131. * d ) from the d-axis current (i AFd ) is subtracted to obtain the deviation (Δi d ) is calculated. q-axis current (i AFq ) is subtracted by a subtractor 138 to obtain the q-axis current command value (i * q ) deviation Δi q is calculated.

[0034] Deviation (Δi d ) is determined, the d-axis current controller 132 outputs the d-axis voltage command value (v * d ) is output to the drive signal generator 141. In addition, the deviation (Δi q ) is determined, the q-axis current controller 139 outputs the q-axis voltage command value (v * q ) is output to the drive signal generation unit 141. Then, the d-axis voltage command value (v * d ) and q-axis voltage command value (v * q ) is output from the drive signal generating section 141 to the inverter circuit 111.

[0035] <Excess current> The apparent power (S AF ), active power (P AF ), reactive power (Q AF ) can be expressed as in equation (1).

[0036]

number

[0037] Here, the current per phase flowing through the active filter device 100 is (i AF ), the power factor is (cosφ), and the effective current value of the order component of the power supply frequency of the current flowing through the active filter device 100 is I AF1 , I AF2 , I AF3 , I AF4 , I AF5 ,.... The harmonic current handled in this disclosure is a current containing harmonic components of the second to fortieth order, and the control amount of the harmonic suppression current control for controlling the harmonic current of the order of 2 to 40 is (Q AFh ), and the control amount of voltage control in the distribution system by reactive power control of the fundamental current (Q AF1 ), equation (1) can be transformed into equation (2).

[0038]

number

[0039] By transforming equation (2) into equation (3), the control amount (Q AF(1) ) into apparent power (S AF ), active power (P AF ), the control amount (Q AFh ) can be expressed as

[0040]

number

[0041] Here, the active power (P AF ) is mainly due to losses (less than 100 W) in the switching element 112, etc., and is less than 1% of the power consumption (for example, 15 kW) of the air conditioner 36, so it can be set to 0. By converting equation (3) into a current dimension, it can be converted into equation (4). As shown in equation (4), the surplus current (I RES ) is the maximum supply current (I AF_ max) to the harmonic compensation current (I AFh ) is subtracted from the surplus current (I RES ) is the power available as fundamental reactive current.

[0042]

number

[0043] <Generation of fundamental wave reactive current command value> Fundamental wave reactive current command value (I * q1 ) is a target value for controlling the voltage of the power distribution system, and is, for example, a phase voltage (input phase voltage (V in )) based on the input phase voltage (V in The current value previously associated with the fundamental reactive current command value (I * q1 ) is set as the fundamental reactive current command value (I * q1 If no limit is placed on the maximum current (maximum supply current (I AF_ In addition, the active filter device 100 may set a command value greater than the receiving capacity (maximum receiving current (I max)) of the inverter device 60. MAX )) AF ), which can result in distribution equipment and / or distribution lines being overloaded. Therefore, in this embodiment, the fundamental wave reactive current command value (I * q1 ), the fundamental wave reactive current command generating unit 140 imposes limitations based on the maximum value of the supply current of the active filter device 100 and the maximum value of the receiving current of the inverter device 60.

[0044] FIG. 3 is a diagram showing an example of the configuration of the fundamental wave reactive current command generating unit 140 according to this embodiment. The fundamental wave reactive current command generating unit 140 includes a command generating unit 135 and a current limiting unit 136. The current limiting unit 136 includes a fundamental wave calculating unit 151, a first current limit value creating unit 152, a second current limit value creating unit 153, a first limiting unit 154, and a second limiting unit 155.

[0045] The command generating unit 135 generates the input phase voltage (V in ) and obtain the input phase voltage (V in ) and the corresponding command value (I * q0 ) to the current limiting unit 136. The fundamental wave calculation unit 151 calculates the load current (I INV ) and obtain the load current (I INV ) fundamental current component (I INV(1) The fundamental wave calculation unit 151 calculates the fundamental wave current component (I INV(1) ) using the power factor PF INV The fundamental wave calculation unit 151 calculates the fundamental wave current component (I INV(1) ) is converted into the harmonic component I detected by the harmonic detector 127. INV(h) the load current (I INV ) and subtract √(I 2 INV -I 2 INV(h) The fundamental wave calculation unit 151 may calculate the fundamental wave current component (I INV(1) ) to the first current limit value creation unit 152.

[0046] The first current limit value creation unit 152 calculates the maximum current received by the inverter device 60 (IMAX The first current limit value (I q(1)_ lim). The first current limit value creating unit 152 first calculates the maximum supply current (I MAX ) is acquired. The first current limit value creation unit 152 also acquires other capacity information related to the power receiving capacity of the inverter device 60, and calculates the maximum receiving current value (I MAX The other capacity information may be the power consumption of the inverter device 60 and the capacity to receive power of the air conditioner 36, which is an appliance equipped with the motor 65 driven by the inverter device 60.

[0047] Then, the first current limit value generating unit 152 calculates the maximum supply current value (I MAX ) and the load current (I INV ) fundamental current component (I INV(1) ) and the first current limit value (I q(1)_ lim) to calculate the first current limit value (I q(1)_ lim) is the maximum current received by the active filter device 100 from the inverter device 60 (maximum current received (I MAX )) AF ) is a limit value for suppressing the supply of

[0048]

number

[0049] The first current limit value creation unit 152 calculates the first current limit value (I q(1)_ lim) to the first limiting unit 154. The first limiting unit 154 sets a first current limit value (I q(1)_ lim) to determine the command value (I * q0 The first limiting unit 154 limits the command value (I * q0 ) and the first current limit value (I q(1)_lim), whichever is smaller, is output to the second limiting unit 155.

[0050] The second current limit value generating unit 153 generates a maximum supply current (I AF_ The second current limit (I SUR The second current limit value generating unit 153 calculates the surplus current (I RES ) and calculate the second current limit value (I SUR ) (I SUR = I RES ).

[0051] The second current limit value creation unit 153 receives the harmonic compensation current (I AFh ) is obtained. The second current limit value generating unit 153 also obtains the maximum supply current value (I AF_ Get the maximum supply current (I AF_ max) is stored in a memory (not shown) as, for example, the rated compensation capacity of the active filter device 100. Then, the second current limit value generating unit 153 calculates the harmonic compensation current (I AFh ) and maximum supply current (I AF_ max) and the excess current (I RES ) and calculate the second current limit value (I SUR )

[0052] The second current limit value creation unit 153 calculates the second current limit value (I SUR ) to the second limiting unit 155. The second limiting unit 155 sets a second current limit value (I SUR ) to obtain the command value (I * q0 The second limiting unit 155 limits the second current limit value (I SUR ) is the smaller of the two, the fundamental wave reactive current command value (I * q1 ) The first limiting portion 154 and the second limiting portion 155 are not limited to being arranged in the order shown in FIG. 3, and may be arranged in the order of the second limiting portion 155 and the first limiting portion 154.

[0053] FIG. 4 shows the relationship between the power consumption and the first current limit value (I q(1)_ lim), the second current limit value (I SUR 4 is a diagram showing an example of the relationship between the maximum supply current (I AF_ max) and harmonic compensation current (I AFh 4, the horizontal axis represents power consumption (kW) and the vertical axis represents current (A).

[0054] As shown in Figure 4, the first current limit value (I q(1)_ lim) and the second current limit value (I SUR ) is reversed at around 5.2kW of power consumption. For example, q(1)_ lim) to calculate the fundamental reactive current command value (I * q1 ), in an operating state in which the power consumption is less than 5.2 kW, the maximum supply current (I AF_ A command value greater than the reference value (max) can be set. For example, if the power consumption is 1 kW, the first current limit value (I q(1)_ lim) is 24.4A, the second current limit value (I SUR ) is 20.0A. The maximum supply current (I AF_ max) is 20.2A, and when the power consumption is 1kW, the first current limit value (I q(1)_ lim) to calculate the fundamental reactive current command value (I * q1 ), the maximum supply current (I AF_ A command value greater than the reference value (max) can be set.

[0055] Also, for example, the second current limit value (I SUR ) is used to calculate the fundamental reactive current command value (I * q1), when the power consumption is greater than 5.2kW, the maximum receiving current (I MAX ) exceeding the compensation current (I AF ) can be supplied to the inverter device 60. For example, if the power consumption is 8 kW, the first current limit value (I q(1)_ lim) is 8.4A, the second current limit value (I SUR ) is 18.7A. The first current limit value (I q(1)_ lim) than the second current limit value (I SUR ) is large, the second current limit value (I SUR ) is used to calculate the fundamental reactive current command value (I * q1 ), from equation (5), the maximum receiving current (I MAX ) exceeding the compensation current (I AF ) can be supplied to the inverter device 60.

[0056] In this embodiment, the first current limit value (I q(1)_ lim) and the second current limit value (I SUR ) and the fundamental reactive current command value (I * q1 ) is limited, the maximum supply current (I AF_ max) of the inverter device 60. AF ) to prevent power distribution facilities and / or distribution lines from being supplied with more power than their capacity allows.

[0057] In this embodiment, the first current limit value (I q(1)_ lim) is calculated by the formula (5), but is not limited to this. For example, the first current limit value generating unit 152 may calculate the load current (I INV ) fundamental current component (I INV(1) ) according to the change in the first current limit value (I q(1)_ lim) may be changed in a stepwise manner.

[0058] In addition, a plurality of active filter devices 100 are incorporated into the air conditioner 36, and the compensation current (I AF ) to the power distribution system. In this case, each of the active filter devices 100 has the components shown in FIG. 2 and is connected in parallel with the inverter device 60 to the power source 20. A compensation current (I AF ) is output.

[0059] 1, an example in which one active filter device 100 is installed for one inverter device 60 has been described, but the present invention is not limited to this. One active filter device 100 may be connected to the power receiving points of a plurality of inverter devices 60.

[0060] 5 is a diagram showing an example of the configuration of an air conditioner 36 in which an active filter device 100 is connected to the power receiving points of two inverter devices 60. The air conditioner 36 includes the active filter device 100, two inverter devices 60, two motors 65, and a product control unit 70. The product control unit 70 controls the two inverter devices 60. The first current limit value generating unit 152 (see FIG. 3) of the active filter device 100 calculates the maximum received current (I MAX ) and the combined load current (I INV ) fundamental current component (I INV(1) ) and the first current limit value (I q(1)_ lim). Then, the second current limit value generating unit 153 (see FIG. 3) calculates the maximum supply current value (I AF_ The second current limit (I SUR ) is calculated, and the fundamental reactive current command value (I * q1 ) is restricted.

[0061] <Losses in switching elements> FIG. 6(a) shows the power consumption of the air conditioner 36 equipped with the active filter device 100 and the compensation current (I AF 6(a) and 6(b) are diagrams showing an example of the relationship between the power consumption of an air conditioner 36 equipped with the active filter device 100 and the loss of the switching element 112 of the active filter device 100. In Fig. 6(a), the horizontal axis represents power consumption (kW) and the vertical axis represents current (A). In Fig. 6(b), the horizontal axis represents power consumption (kW) and the vertical axis represents loss (W).

[0062] FIG. 6(a) shows the case where both the harmonic and the fundamental are compensated. In FIG. 6(a), the compensation current (I AF ) is a constant 15.5A regardless of the power consumption. AFh ) increases as the power consumption increases. On the other hand, the fundamental compensation current (I AF1 ) decreases as the power consumption increases. For example, when the power consumption is 3 kW, the harmonic compensation current (I AFh ) is 4.4A, and the fundamental compensation current (I AF1 ) is 14.8A, while when the power consumption is 17.8kW, the harmonic compensation current (I AFh ) is 15.6A, and the fundamental compensation current (I AF1 ) is 0A.

[0063] At this time, as shown in FIG. 6(b), when only the harmonics are compensated, the loss of the switching element 112 increases as the power consumption increases. However, when both the harmonics and the fundamental are compensated, the loss of the switching element 112 increases as the power consumption decreases. In other words, the compensation current (I AF ) is the fundamental component of the fundamental compensation current (I AF1 ) increases, the loss in the switching element 112 increases.

[0064] In order to suppress an increase in loss and a rise in temperature of the switching element 112, the compensation current (I AFIt is desirable to keep the loss of the switching element 112 constant regardless of the content rate of the fundamental wave component in the switching element 112. Therefore, in the following modified example, a configuration example of the active filter apparatus 100 in which the loss of the switching element 112 is kept constant will be described.

[0065] <Modification> 7 is a diagram showing an example of the configuration of a fundamental wave reactive current command generating unit 160 of an active filter device 100 according to a modified example. Components similar to those of the fundamental wave reactive current command generating unit 140 will be described with the same reference numerals. The fundamental wave reactive current command generating unit 160 includes a command generating unit 135 and a current limiting unit 150. The current limiting unit 150 includes a fundamental wave calculating unit 151, a first current limit value creating unit 152, a second current limit value creating unit 153, a first limiting unit 154, a second limiting unit 155, and a maximum supply current value calculating unit 156.

[0066] In a variant, the harmonic compensation current maximum value (I AF_ max1) and the maximum value of the fundamental reactive current (I AF _max2), the maximum supply current (I AF_ The maximum harmonic compensation current (I AF_ max1) is the compensation current (I AF ) is the maximum supply current when only harmonic components are supplied (I AF_ max) and the maximum value of the fundamental reactive current (I AF _max2) is the compensation current (I AF ) is the maximum supply current when only the fundamental wave component is supplied (I AF_ max) is the maximum harmonic compensation current (I AF_ max1) and the maximum value of the fundamental reactive current (I AF _max2) is I AF_ max1 > I AF The relationship _max2 holds.

[0067] The maximum supply current calculation unit 156 calculates the load current (I INV) is obtained. The maximum supply current calculation unit 156 also obtains the maximum harmonic compensation current value (I AF_ max1), maximum value of fundamental reactive current (I AF _max2), rated current (I typ ) to obtain the rated current (I typ ) is the compensation current (I AF ) as the compensation current (I AF ) is the maximum harmonic compensation current (I AF_ max1) is the load current (I INV ) Then, the supply current maximum value calculation unit 156 calculates the harmonic compensation current maximum value (I AF_ max1), maximum value of fundamental reactive current (I AF _max2), rated current (I typ ), load current (I INV ) to the maximum supply current (I AF_ Calculate the maximum supply current (I max) for the modified example. AF_ max) is the load current (I INV ) changes depending on the change.

[0068]

number

[0069] The second current limit value creation unit 153 calculates the maximum supply current value (I AF_ max) and calculate the second current limit value (I SUR Then, the second limiting unit 155 calculates the calculated second current limiting value (I SUR ) to obtain the fundamental reactive current command value (I * q1 ) to limit

[0070] FIG. 8 shows the load current (I INV ) and maximum supply current (I AF_ As shown in FIG. 8, the load current (I INV ) is 0 (A), the maximum supply current (IAF_ max) is the maximum value of the fundamental reactive current (I AF _max2), and the load current (I INV ) is the rated current (I typ ) is equal to the maximum supply current (I AF_ max) is the maximum harmonic compensation current (I AF_ max1).

[0071] FIG. 9(a) shows the power consumption of the air conditioner 36 equipped with the active filter device 100 according to the modified example and the compensation current (I AF 9(a) and 9(b) are graphs showing the relationship between the power consumption of an air conditioner 36 equipped with an active filter device 100 according to a modified example and the loss of the switching element 112 of the active filter device 100. In Fig. 9(a), the horizontal axis represents power consumption (kW) and the vertical axis represents current (A). In Fig. 9(b), the horizontal axis represents power consumption (kW) and the vertical axis represents loss (W).

[0072] As shown in Fig. 9(a), for example, when the power consumption is 3 kW, the fundamental compensation current (I AF1 ) is 11.2A, harmonic compensation current (I AFh ) is 4.4A, and the compensation current (I AF ) is 12.0 A, and the compensation current (I AF 6(a). Also, unlike the case shown in FIG. 6(a), the compensation current (I AF ) becomes larger. This is because, in the modified example, the larger the power consumption, the larger the maximum supply current (I AF_ max) becomes larger. In the modified example, the compensation current (I AF ) is different, the loss of the switching element 112 when the power consumption is low is suppressed, and as shown in FIG. 9(b), the active filter device 100 AFh ) and the fundamental compensation current (I AF1) can be output, the loss of the switching element 112 can be kept constant.

[0073] In a variant, the load current (I INV ) is small, the maximum supply current (I AF_ max) is set low. As a result, the compensation current (I AF ) can be suppressed, and the loss of the switching element 112 can be kept constant as shown in FIG. 9(b). In addition, in the modified example, by using a wide band gap semiconductor for the switching element 112, the maximum harmonic compensation current (I AF_ max1) and the maximum value of the fundamental reactive current (I AF The difference with _max2) can be reduced.

[0074] In addition, in the modified example, I AF_ max1 > I AF Although the case of max2 has been described, the present invention is not limited to this. Depending on the switching loss characteristics, conduction loss characteristics, or switching frequency of the switching element 112, the compensation current (I AF ) is the harmonic component of the harmonic compensation current (I AFh ) increases, the loss of the switching element 112 increases, that is, I AF_ max1 < I AF In this case, I in equation (6) AF_ max1 and I AF _max2 and the maximum supply current (I AF_ max) is calculated.

[0075] In addition, in the modified example, the maximum supply current (I AF_ max) flowing through the inverter device 60 is calculated by the equation (6), but is not limited to this. INV The maximum supply current (I AF_max) may be changed in steps.

[0076] <Effects> The active filter apparatus 100 of the present disclosure is connected to a power receiving point of an inverter apparatus 60 that receives power from a power source 20 via a distribution line 21, and includes a current source 110 that supplies a harmonic current to the power receiving point and a fundamental reactive current to the power source 20 via the distribution line 21, and a control unit 120 that controls the current supplied by the current source 110, wherein the control unit 120 obtains the received current of the inverter apparatus 60 and limits the fundamental reactive current using a first current limit value that is set based on the maximum received current value of the inverter apparatus 60 and the received current of the inverter apparatus 60. In this case, compared to when a current is supplied from the active filter apparatus 100 to the distribution line 21 regardless of the maximum received current value of the inverter apparatus 60, it is possible to cause the active filter apparatus 100 to supply a current that is appropriate for the capacity of the power distribution facility and / or the distribution line 21. Here, the control unit 120 obtains the fundamental current of the received current of the inverter device 60 and varies the first current limit value according to a change or amount of change in the fundamental current. In this case, a larger amount of fundamental current can be supplied from the active filter device 100 compared to when the first current limit value is determined from the received current. Furthermore, the control unit 120 acquires capability information relating to the power receiving capability of the inverter device 60 or an appliance equipped with a load driven by the inverter device 60, and determines the maximum receiving current value from the acquired capability information. In this case, a current suited to the capacity of the power distribution facility and / or the power distribution line 21 can be supplied from the active filter device 100, compared to a case in which the first current limit value is not determined according to capability information relating to the power receiving capability of the appliance. Furthermore, the control unit 120 limits the fundamental reactive current using the smaller of the first current limit value and a second current limit value set based on the maximum supply current value of the active filter device 100 and the harmonic current supplied to the power receiving point. In this case, it is possible to suppress power supply that exceeds the supply capacity of the active filter device 100. Furthermore, the control unit 120 varies the maximum supply current value in accordance with a change or amount of change in the received current of the inverter device 60. In this case, it is possible to suppress an increase in loss and a rise in temperature of the switching elements compared to when the maximum supply current value is not varied. Furthermore, the current source 110 has a plurality of switching elements, each of which includes a wide bandgap semiconductor element. In this case, compared to when wide bandgap semiconductors are not used for the plurality of switching elements, loss in the switching elements can be reduced and the maximum supply current can be made constant. The active filter device 100 is also installed in an air conditioner 36 that includes a compressor to which power generated using the inverter device 60 is supplied. In this case, the air conditioner 36 can have the active filter device 100 supply a current that is suitable for the capacity of the power distribution facility and / or the power distribution line 21, compared to when the active filter device 100 supplies a current to the power distribution line 21 regardless of the maximum value of the received current of the inverter device 60. Moreover, the active filter apparatus 100 of the present disclosure is connected to the power receiving points of the plurality of inverter apparatuses 60, and the first current limit value is set by the combined maximum received current value of the plurality of inverter apparatuses 60 and the combined received current of the plurality of inverter apparatuses 60. In this case, even when a plurality of inverter apparatuses 60 are mounted on an apparatus, it is possible to make the active filter apparatus 100 supply a current suited to the capacity of the power distribution facility and / or the power distribution line 21, compared to when a current is supplied from the active filter apparatus 100 to the power distribution line 21 regardless of the maximum received current value of the inverter apparatuses 60. Moreover, an air conditioning device 36 of the present disclosure includes the active filter device 100 according to claim 1 or 2, and the inverter device 60. In this case, compared to when the active filter device 100 supplies current to the distribution line 21 regardless of the maximum value of the received current of the inverter device 60, it is possible to have the active filter device 100 supply a current that is suitable for the capacity of the distribution facility and / or the distribution line 21.

[0077] Although the embodiments have been described above, the technical scope of the present disclosure is not limited to the scope of the above-described embodiments. It is clear from the claims that combinations of two or more of the above-described embodiments, and various modifications or improvements to the above-described embodiments, are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0078] 10... Customer facility, 20... Power source, 60... Inverter device, 100... Active filter device, 110... Current source, 120... Control unit, 150... Current limiting unit

Claims

1. A power conversion device connected to a power receiving point of an inverter device that receives power from a power distribution facility via a power distribution line, a supply circuit that supplies harmonic current to the power receiving point and supplies fundamental reactive current to the power distribution equipment via the distribution line; a control unit that controls the current supplied by the supply circuit; Equipped with The control unit acquiring a received current of the inverter device; limiting the fundamental reactive current using a first current limit value that is set based on the maximum value of the received current of the inverter device and the received current of the inverter device; Power conversion device.

2. The control unit acquiring a fundamental current of a current received by the inverter device, and varying the first current limit value in accordance with a change or an amount of change in the fundamental current; The power conversion device according to claim 1 .

3. The control unit acquiring capacity information relating to the power supply capacity of the inverter device or an appliance equipped with a load driven by the inverter device; determining the maximum supply current value from the acquired capacity information; The power conversion device according to claim 1 or 2.

4. The control unit limiting the fundamental reactive current using the smaller of a second current limit value set by the maximum supply current of the power conversion device and the harmonic current supplied to the power receiving point, and the first current limit value; The power conversion device according to claim 1 or 2.

5. The control unit The maximum supply current value is varied in accordance with a change or an amount of change in the received current of the inverter device. The power conversion device according to claim 4.

6. the supply circuit has a plurality of switching elements; The switching element includes a wide bandgap semiconductor element. The power conversion device according to claim 1 or 2.

7. the power conversion device is provided in a heat pump system including a compressor to which power generated using the inverter device is supplied. The power conversion device according to claim 1 or 2.

8. connected to the power receiving points of the plurality of inverter devices, the first current limit value is set by a maximum value of received currents of the plurality of inverter devices combined and a received current of the plurality of inverter devices combined; The power conversion device according to claim 1 or 2.

9. A heat pump system comprising: the power conversion device according to claim 1 or 2; and the inverter device.

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