JP7658073B2 - Power Conversion Equipment - Google Patents

Description

This disclosure relates to a power conversion device.

For example, a technology is known that drives a load device using power from both a solar power source and a commercial power source (see Patent Document 1).

With this technology, even if the amount of power that a solar power generation source can supply fluctuates due to factors such as the duration of sunlight and weather, the load device can be operated stably by constantly using power from a commercial power source.

JP 2017-184347 A

However, in the above technology, power from a photovoltaic power source is controlled to be supplied to a load device with priority over power from a commercial power source. As a result, for example, the efficiency of using power from a commercial power source may be relatively low.

In view of the above problems, the objective of the present invention is to provide a technology that can drive a load device more stably and efficiently using power from a solar power source and a commercial power source.

In order to achieve the above object, in one embodiment of the present disclosure,
A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least one of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
the load driving unit selects either a first operation for improving the efficiency of power utilization of the solar power generation power source of the two power sources or a second operation for improving the efficiency of power utilization of the commercial power source of the two power sources in response to a change in the input status of power from the two power sources among a first state in which power is input only from the solar power generation power source of the two power sources, a second state in which power is input from both the solar power generation power source and the commercial power source of the two power sources, and a third state in which power is input only from the commercial power source of the two power sources, thereby transitioning the operation so as to drive the load device more stably and more efficiently.
A power converter is provided.

In another embodiment,
A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least the solar power source of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
when power is input from the commercial power source in a state in which power is input only from the solar power generation power source of the two power sources, the load driving unit shifts its operation so as to prioritize a second efficiency from the input of power from the commercial power source to the conversion of power into the specified AC power over a first efficiency from the power generation of the solar power generation power source to the conversion of power into the specified AC power.
A power converter is provided.

In still another embodiment,
A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least the solar power source of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
the load driving unit operates, in a state in which power is input from both of the two power sources, to prioritize a second efficiency from the input of power from the commercial power source to the conversion into the specified AC power over a first efficiency from the power generation of the photovoltaic power source to the conversion into the specified AC power, and when the input of power from the commercial power source is interrupted, shifts its operation to enhance the first efficiency.
A power converter is provided.

In still another embodiment,
A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least one of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
the load driving unit selects either a first operation for improving the efficiency of power usage of the solar power generation power source of the two power sources, or a second operation for improving the efficiency of power usage of the commercial power source of the two power sources, in accordance with the input and cut-off of power from one of the two power sources while power input from the other power source is continuing, thereby shifting the operation so as to drive the load device more stably and more efficiently;
A power converter is provided.

According to the above-described embodiment, the load device can be driven more stably and efficiently using power from a solar power source and a commercial power source.

FIG. 1 is a diagram illustrating an example of a configuration of an electric motor drive system. FIG. 13 is a diagram illustrating another example of the configuration of an electric motor drive system. FIG. 13 is a diagram showing yet another example of the configuration of the electric motor drive system. 4 is a state transition diagram illustrating the relationship between the power supply states from a photovoltaic power generation power source and a commercial power source and the control state of a power conversion device. FIG.

The following describes the embodiment with reference to the drawings.

[Configuration of the electric motor drive system]
First, the configuration of an electric motor drive system 1 according to this embodiment will be described with reference to FIGS.

Figures 1 to 3 are diagrams showing an example, another example, and yet another example of the configuration of the electric motor drive system 1 according to this embodiment, respectively.

The electric motor drive system 1 according to this embodiment drives the electric motor M based on the power input from at least one of the photovoltaic power source PPS and the commercial power source CPS by the power conversion device 100.

As shown in Figures 1 to 3, the motor drive system 1 includes a solar power generation power source PPS, a commercial power source CPS, a circuit breaker 10, a switch 20, a circuit breaker 30, a circuit breaker 40, a detection circuit 50, a power conversion device 100, and an electric motor M.

The photovoltaic power source PPS includes a solar cell SC. The photovoltaic power source PPS (solar cell SC) is connected to the power conversion device 100 via a DC input line DC_IL including a positive input line P_IL and a negative input line N_IL.

In addition, a backflow prevention diode BPD that allows only current flow from the photovoltaic power source PPS (solar cell SC) to the power conversion device 100 is arranged on the DC input line DC_IL (positive input line P_IL). The backflow prevention diode BPD may also be arranged on the negative input line N_IL instead of the positive input line P_IL. In this case, the backflow prevention diode BPD is arranged to allow only current flow from the power conversion device 100 to the photovoltaic power source PPS (solar cell SC).

The commercial power source CPS is connected to the power conversion device 100 via an AC input line AC_IL that includes an R-phase input line R_IL, an S-phase input line S_IL, and a T-phase input line T_IL.

The circuit breaker 10 is disposed on the AC input lines AC_IL (R-phase input line R_IL, S-phase input line S_IL, and T-phase input line T_IL). The circuit breaker 10 is configured to be switchable between a state in which the AC input lines AC_IL are closed (hereinafter, "closed state") and a state in which the AC input lines AC_IL are opened and the power supply from the commercial power source CPS to the power conversion device 100 is cut off (hereinafter, "cut off state"). The circuit breaker 10 is, for example, a molded case circuit breaker (MCCB).

The switch 20 is disposed on the AC input lines AC_IL (R-phase input line R_IL, S-phase input line S_IL, and T-phase input line T_IL). The switch 20 is configured to be switchable between a state in which the AC input lines AC_IL are closed (closed state) and a state in which the AC input lines AC_IL are opened (hereinafter, "open state"). The switch 20 is, for example, a normally open magnet contactor (MC).

The circuit breaker 30 is disposed on the DC input line DC_IL (positive input line P_IL and negative input line N_IL). The circuit breaker 30 is configured to be switchable between a state in which the DC input line DC_IL is closed (closed state) and a state in which the DC input line DC_IL is opened and the power supply from the photovoltaic power source PPS to the power conversion device 100 is cut off (cut off state). The circuit breaker 30 is, for example, an MCCB.

The circuit breaker 40 is disposed on an AC input line (hereinafter, "detection AC input line") that supplies power to the detection circuit 50 and is drawn from the R-phase input line R_IL and the T-phase input line T_IL. The circuit breaker 40 is configured to be switchable between a state in which the detection AC input line is closed (closed state) and a state in which the detection AC input line is opened and the power supply from the commercial power source CPS is cut off (cut state). The circuit breaker 40 is, for example, an MCCB.

As shown in Figures 1 and 2, the detection circuit 50 includes a transformer 51 and circuit sections 52 to 54. The detection circuit 50 may be installed, for example, in the same location as the facility in which the power conversion device 100 and the electric motor M are installed.

The transformer 51 transforms (steps down) the AC power of the detection AC input line to a specified voltage and supplies it to the circuit sections 52 to 54 that are connected in parallel.

The circuit section 52 is always in a conductive state, and is energized when the circuit breaker 40 is closed, i.e., when power is being supplied to the detection circuit 50. The coil section PW_C is disposed in the circuit section 52.

When the circuit breaker 40 is in the closed state and the circuit section 52 is energized, the coil section PW_C uses magnetic action to mechanically transition the normally open switch PW_S (described below) to a closed state and maintains it in that closed state.

The circuit section 53 includes the switches 10_S and PW_S and the coil section 20_C. The circuit section 53 is in a conductive state when both the switches 10_S and PW_S are in a closed state.

The switch 10_S is, for example, a normally open electromagnetic relay. The switch 10_S is configured to switch between an open state and a closed state in conjunction with the interrupted state and closed state of the circuit breaker 10, respectively.

The switch PW_S is, for example, a normally open electromagnetic relay. When the coil portion PW_C is energized, the switch PW_S transitions from an open state to a closed state due to magnetic action, and maintains the closed state as long as the coil portion PW_C remains energized.

When the circuit breaker 40 is in the closed state, the switches 10_S and PW_S are both in the closed state, and the circuit unit 53 is energized, the coil unit 20_C mechanically transitions the switch 20 to a closed state through magnetic action and maintains the closed state.

The circuit section 54 includes the switches 20_S and 30_S and the coil section PS_C. The circuit section 54 is in a conductive state when the switches 20_S and 30_S are both in a closed state.

The switch 20_S is, for example, a normally open electromagnetic relay. The switch 20_S is configured to switch between an open state and a closed state in conjunction with the open state and the closed state of the switch 20, respectively. That is, when power is supplied from the commercial power source CPS to the power conversion device 100, the switch 20_S is maintained in a closed state.

The switch 30_S is, for example, a normally open electromagnetic relay. The switch 30_S is configured to switch between a closed state and an open state in conjunction with the closed state and the interrupted state of the circuit breaker 30, respectively. That is, when power is supplied from the photovoltaic power source PPS to the power conversion device 100, the switch 30_S is maintained in a closed state.

The coil section PS_C is energized when the circuit breaker 40 is in the closed state and the switches 20_S and 30_S are both in the closed state. When the coil section PS_C is energized, a signal indicating that the coil section PS_C is in an energized state (hereinafter, the "first detection signal") is output, and the first detection signal is received by the power conversion device 100 (control device 150) via, for example, a one-to-one communication line or the like.

When power from a solar power generation source is input to the power conversion device 100, the circuit breaker 30 is usually switched from the interrupted state to the closed state by a user operation. This allows power to be supplied from the solar power generation source PPS to the power conversion device 100.

When power from the commercial power source CPS is supplied to the power conversion device 100, the user usually first switches the circuit breaker 40 from the interrupted state to the closed state. This starts the supply of power to the detection circuit 50, and in response to the energization of the coil portion PW_C of the circuit portion 52, the switch PW_S of the circuit portion 53 switches from the open state to the closed state.

Next, after the circuit breaker 40 is closed, the circuit breaker 10 is transitioned from the interrupted state to the closed state by the user's operation. As a result, in conjunction with the transition of the circuit breaker 10 from the interrupted state to the closed state, the switch 10_S of the circuit unit 53 transitions from the open state to the closed state. Therefore, when both switches PW_S and 10_S are in the closed state, the circuit unit 53 is energized, and in response to the energization of the coil unit 20_C, the switch 20 transitions from the open state to the closed state. Therefore, when both the circuit breaker 10 and the switch 20 transition to the closed state, power supply from the commercial power source CPS to the power conversion device 100 begins.

When power from the commercial power source CPS is supplied to the power conversion device 100, the circuit breaker 10 may first be switched to a closed state by a user operation, and then the circuit breaker 40 may be switched to a closed state. Also, as described below, the supply and cut-off of power from the photovoltaic power source PPS to the power conversion device 100 may be switched automatically. In this case, the circuit breaker 30 may be switched between a cut-off state and a closed state in response to an external signal. Similarly, as described below, the supply and cut-off of power from the commercial power source CPS to the power conversion device 100 may be switched automatically. In this case, the circuit breaker 10 and the switch 20 may be switched between their states (cut-off state or open and closed states) in response to an external signal.

When power is supplied to the power conversion device 100 from both the photovoltaic power source PPS and the commercial power source CPS, as described above, the switches 30_S and 20_S are closed in conjunction with the closed states of the circuit breaker 30 and the switch 20. Therefore, the control device 150 can recognize (understand) the state in which power is being supplied to the power conversion device 100 from both the photovoltaic power source PPS and the commercial power source CPS when the switches 30_S and 20_S are closed and the first detection signal is input.

Also, as shown in FIG. 3, circuit units 55 and 56 may be provided instead of circuit unit 54.

The circuit unit 55 is used to detect a state in which power is being supplied from the photovoltaic power source PPS to the power conversion device 100. The circuit unit 56 is used to detect a state in which power is being supplied from the commercial power source CPS to the power conversion device 100. The circuit unit 55 is provided with a switch 30_S and a coil unit PPS_C. When the switch 30_S is closed and the coil unit PPS_C is energized, a signal indicating that the coil unit PPS_C is energized (hereinafter, the "second detection signal") is output, and the second detection signal is taken into the power conversion device 100 (control device 150). As a result, the control device 150 can detect (recognize) that power is being supplied from the photovoltaic power source PPS to the power conversion device 100 by inputting the second detection signal. The circuit unit 56 is also provided with a switch 20_S and a coil unit CPS_C. When the coil section CPS_C is energized due to the closed state of the switch 20_S, a signal indicating that the coil section CPS_C is energized (hereinafter, the "third detection signal") is output, and the third detection signal is taken into the power conversion device 100 (control device 150). As a result, the control device 150 can detect (recognize) a state in which power is being supplied from the commercial power source CPS to the power conversion device 100 by receiving the third detection signal. In addition, the control device 150 can detect (recognize) a state in which power is being supplied from both the photovoltaic power source PPS and the commercial power source CPS to the power conversion device 100 by receiving both the second detection signal and the third detection signal.

In addition, in FIG. 3, the circuit unit 54 in the electric motor drive system 1 in FIG. 1 is replaced with the circuit units 55 and 56, but the circuit unit 54 in the electric motor drive system 1 in FIG. 2 may also be replaced with the circuit units 55 and 56.

As described above, the power conversion device 100 generates AC power having a predetermined voltage and a predetermined frequency from power supplied from at least one of the solar power generation power source PPS and the commercial power source CPS, and drives the electric motor M. Specifically, when power (DC power) is input only from the solar power generation power source PPS, the power conversion device 100 converts the DC power input from the solar power generation power source PPS into a predetermined AC power and outputs it to the electric motor M. When power (AC power) is input only from the commercial power source CPS, the power conversion device 100 rectifies the AC power of the commercial power source CPS and converts it into DC power, and converts the DC power into a predetermined AC power and outputs it to the electric motor M. When power is input from both the solar power generation power source PPS and the commercial power source CPS, the power conversion device 100 converts both the DC power input from the solar power generation power source PPS and the DC power converted from the AC power of the commercial power source CPS into a predetermined AC power and outputs it to the electric motor M.

The power conversion device 100 includes an AC input unit ACIN, a rectifier circuit 110, a DC input unit DCIN, a smoothing circuit 120, an inverter circuit 130, an AC output unit ACOUT, a ground terminal G, a charging circuit 140, and a control device 150.

The AC input unit ACIN (an example of a second input unit) is used to input three-phase AC power of R, S, and T phases from the outside. In this example, the AC input unit ACIN is connected to the AC input line AC_IL and can receive three-phase AC power of R, S, and T phases from the commercial power source CPS. The AC input unit ACIN includes an AC input terminal R, an AC input terminal S, and an AC input terminal T that are connected to the R-phase input line R_IL, the S-phase input line S_IL, and the T-phase input line T_IL, respectively.

The rectifier circuit 110 is configured to be able to rectify three-phase AC power of R phase, S phase, and T phase input from the AC input unit ACIN and output DC power. The rectifier circuit 110 has positive and negative output terminals connected to one end of a positive line PL and a negative line NL, respectively, and can output DC power to the smoothing circuit 120 through the positive line PL and the negative line NL. The rectifier circuit 110 is, for example, a bridge-type full-wave rectifier circuit including six diodes, in which three sets of two-diode series connections constituting upper and lower arms are connected in parallel.

The smoothing circuit 120 suppresses and smoothes pulsations in the DC power output from the rectifier circuit 110 and the DC power regenerated from the inverter circuit 130.

The smoothing circuit 120 includes a smoothing capacitor 122 and a reactor 124.

The smoothing capacitor 122 is arranged in parallel with the rectifier circuit 110 and the inverter circuit 130 in the path connecting the positive line PL and the negative line NL.

The smoothing capacitor 122 is repeatedly charged and discharged as appropriate to smooth the DC power output from the rectifier circuit 110, the DC power output (regenerated) from the inverter circuit 130, and the DC power input from the DC input section DCIN.

There may be only one smoothing capacitor 122. Alternatively, multiple smoothing capacitors 122 may be arranged, and the multiple smoothing capacitors 122 may be connected in parallel or in series between the positive line PL and the negative line NL. Alternatively, the multiple smoothing capacitors 122 may be configured in such a way that two or more series-connected smoothing capacitors 122 are connected in parallel between the positive line PL and the negative line NL.

The reactor 124 is provided on the positive line PL between the rectifier circuit 110 and the smoothing capacitor 122 (specifically, the branch point of the path in which the smoothing capacitor is arranged). For example, as shown in Figs. 1 and 3, the reactor 124 may be arranged to connect between reactor connection terminals LT1 and LT2 that are drawn out from both ends of the positive line PL that is divided between the rectifier circuit 110 and the smoothing capacitor 122. Also, for example, as shown in Fig. 2, the reactor 124 may be built into the housing of the power conversion device 100.

The reactor 124 generates a voltage to appropriately prevent changes in the current, while smoothing the DC power output from the rectifier circuit 110, the DC power output (regenerated) from the inverter circuit 130, and the DC power input from the DC input section DCIN.

The reactor 124 may be omitted. In this case, in FIG. 1 and FIG. 3, a short-circuit conductor is connected between the reactor connection terminals LT1 and LT2.

The inverter circuit 130 has its positive and negative input terminals connected to the other ends of the positive line PL and the negative line NL. The inverter circuit 130 converts the DC power supplied from the smoothing circuit 120 through the positive line PL and the negative line NL into three-phase AC power of U phase, V phase, and W phase having a predetermined frequency and a predetermined voltage by the switching operation of the semiconductor switching elements, and outputs it to the electric motor M. The semiconductor switching elements may be, for example, silicon (Si) IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The semiconductor switching elements may also be, for example, semiconductor elements using wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN).

The inverter circuit 130 includes, for example, six semiconductor switching elements, and is configured to include a bridge circuit in which three sets of series connections (switch legs) of two semiconductor switching elements constituting upper and lower arms are connected in parallel between the positive line PL and the negative line NL. The inverter circuit 130 may output three-phase AC power through U-phase wires, V-phase wires, and W-phase wires drawn from the connection points of the three sets of upper and lower arms. In addition, a free-wheeling diode may be connected in parallel to each of the six semiconductor switching elements.

The AC output unit ACOUT is connected to the electric motor M through an AC output line AC_OL including a U-phase output line U_OL, a V-phase output line V_OL, and a W-phase output line W_OL. The AC output unit ACOUT includes an AC output terminal U, an AC output terminal V, and an AC output terminal W that output the U-phase, V-phase, and W-phase AC powers generated by the inverter circuit 130 to the U-phase output line U_OL, the V-phase output line V_OL, and the W-phase output line W_OL, respectively.

The charging circuit 140 is provided in a portion of the positive line PL between the rectifier circuit 110 and the smoothing capacitor 122. For example, as shown in Figs. 1 and 3, the charging circuit 140 may be provided in a portion of the positive line PL between the rectifier circuit 110 and the reactor 124. Also, as shown in Fig. 2, the charging circuit 140 may be provided in a portion of the positive line PL between the reactor 124 and the smoothing capacitor 122. The charging circuit 140 includes a switch 142 and a charging resistor 144.

The switch 142 is provided in a portion of the positive line PL between the rectifier circuit 110 and the smoothing circuit 120 (reactor 124). The switch 142 is configured to be able to open and close the positive line PL. The switch 142 is, for example, a switching element such as a thyristor, a triac, or a relay.

The charging resistor 144 (an example of a resistor) is connected in parallel with the switch 142.

The charging circuit 140 functions so that the current flowing through the positive line PL toward the smoothing circuit 120 passes through the switch 142 when the switch 142 is on, and passes through the charging resistor 144 when the switch 142 is off. As a result, when the power conversion device 100 is started up, the switch 142 is turned off so that the current flows through the charging resistor 144, and a relatively large inrush current can be prevented when charging the smoothing capacitor 122. When the smoothing capacitor 122 is charged to a certain extent and the voltage between the positive line PL and the negative line NL becomes relatively high, the power conversion device 100 turns on the switch 142, and the current can flow to the positive line PL through the switch 142, which has a relatively low electrical resistance. Specifically, when a voltage detection circuit (not shown) that detects the voltage between the positive line PL and the negative line NL detects a voltage equal to or higher than a predetermined value, it is determined that the inrush current has been suppressed, and the switch 142 is turned on from the off state.

The DC input unit DCIN is used to input DC power from the outside. In this example, the DC input unit DCIN is connected to the DC input line DC_IL and can receive DC power from a photovoltaic power source PPS (solar cell SC). The DC input unit DCIN includes a positive DC terminal P and a negative DC terminal N.

The positive DC terminal P is drawn from the positive line PL. For example, as shown in FIG. 1 and FIG. 3, the positive DC terminal P may be drawn from a portion of the positive line PL between the charging circuit 140 and the inverter circuit 130, specifically, between the reactor 124 and the inverter circuit 130. Also, as shown in FIG. 2, the positive DC terminal P may be drawn from a portion of the positive line PL between the rectifier circuit 110 and the charging circuit 140, specifically, between the reactor 124 and the charging circuit 140. Also, the positive DC terminal P is connected to the positive input line P_IL outside the power conversion device 100.

The negative DC terminal N is drawn from any position on the negative line NL. In this example, the negative DC terminal N is connected to a portion of the negative line NL between the smoothing circuit 120 (smoothing capacitor 122) and the inverter circuit 130 inside the power conversion device 100. In addition, the negative DC terminal N is connected to the negative input line N_IL outside the power conversion device 100.

The ground terminal G is connected to the electric motor M and grounds the electric motor M.

The control device 150 controls the power conversion device 100.

The functions of the control device 150 may be realized by any hardware or any combination of hardware and software. For example, the control device 150 is configured around a computer including a CPU (Central Processing Unit), a memory device such as a RAM (Random Access Memory), a non-volatile auxiliary storage device such as a ROM (Read Only Memory), and an interface device for input and output with the outside.

Specifically, the control device 150 outputs to the inverter circuit 130 (specifically, the gates of each switching element) and uses the inverter circuit 130 to drive the electric motor M so that it satisfies specified operating conditions. In other words, the control device 150 generates a control signal for driving the electric motor M in accordance with the specified operating conditions and outputs it to the inverter circuit 130.

Furthermore, the control device 150 may control the operation of the inverter circuit 130 so that the efficiency of power utilization of the solar power source PPS (an example of a first efficiency) is relatively high, assuming that the motor M satisfies a predetermined operating condition. The efficiency of power utilization of the solar power source PPS includes the power generation efficiency of the solar power source PPS and the conversion efficiency when converting the power input from the solar power source PPS into three-phase AC power that drives the motor M. In other words, the control device 150 may generate a control signal for relatively increasing the efficiency of power utilization of the solar power source PPS and output it to the inverter circuit 130.

For example, the control device 150 may perform MPPT (Maximum Power Point Tracking) control for the photovoltaic power source PPS (solar cell SC) on the premise that the motor M satisfies a predetermined operating condition. MPPT control is a control method in which the operating point (output voltage) of the photovoltaic power source PPS (solar cell SC) is tracked so that the generated power (output power) is maximized. For example, the MPPT control may be realized by a hill climbing method or the like. The control device 150 outputs a control signal to the inverter circuit 130, and uses the inverter circuit 130 to adjust the voltage between the positive line PL and the negative line NL of the power conversion device 100 (hereinafter, "DC link voltage") to realize the MPPT control. This is because the DC link voltage corresponds to the output voltage of the photovoltaic power source PPS. In other words, the control device 150 may generate a control signal for tracking the DC link voltage so that the generated power of the photovoltaic power source PPS (solar cell SC) is maximized, and output the control signal to the inverter circuit 130. This allows the control device 150 to maximize the power generation efficiency of the solar power source PPS (solar cell SC).

Also, for example, the control device 150 may control the inverter circuit 130 to relatively increase (e.g., maximize) the conversion efficiency from the power input of the solar power generation power source PPS to three-phase AC power for driving the motor M, assuming that the motor M satisfies a specified operating condition. Specifically, the control device 150 may control the inverter circuit 130 to relatively decrease (e.g., substantially minimize) the loss of the switching elements when converting the power input from the solar power generation power source PPS into three-phase AC power for driving the motor M, on the assumption that the motor M satisfies a specified operating condition.

Furthermore, the control device 150 may control the operation of the inverter circuit 130 so that the efficiency of power usage from the commercial power source CPS (an example of a second efficiency) is relatively high, assuming that the motor M satisfies a specified operating condition. The efficiency of power usage from the commercial power source CPS includes the conversion efficiency from the power input of the commercial power source CPS to three-phase AC power for driving the motor M. In other words, the control device 150 may generate a control signal for relatively increasing the efficiency of power usage from the commercial power source CPS, and output it to the inverter circuit 130.

Furthermore, for example, the control device 150 may control the inverter circuit 130 to relatively increase (e.g., substantially maximize) the conversion efficiency from the power input of the commercial power source CPS to three-phase AC power for driving the motor M, on the premise that the motor M satisfies a predetermined operating condition. Specifically, the control device 150 may control the inverter circuit 130 to relatively decrease (e.g., substantially minimize) the loss of the switching elements when converting the power input from the commercial power source CPS to three-phase AC power for driving the motor M, on the premise that the motor M satisfies a predetermined operating condition.

The electric motor M (an example of a specified load device) is electrically driven by power supplied from the power conversion device 100 through the AC output lines AC_OL (U-phase output line U_OL, V-phase output line V_OL, and W-phase output line W_OL). The electric motor M drives, for example, a pump that draws up water.

[Method of controlling a power conversion device]
Next, a method of controlling the power conversion device 100 will be described with reference to FIG.

Figure 4 is a state transition diagram that explains the relationship between the power supply state from the photovoltaic power source PPS and the commercial power source CPS and the control state of the power conversion device 100.

<First example of control method>
In this example, the circuit breaker 30 is always in a closed state, the states of the circuit breakers 10 and 40 are switched manually, and as described above, the open/closed state of the switch 20 is switched in conjunction with the states of the circuit breakers 10 and 40. Also, in this example, the state of the circuit breaker 40 may be switched by a user's operation, or may be always maintained in a closed state. The following description will be given on the assumption of the former.

In this example, when the weather at the installation location of the photovoltaic power source PPS is good or when the hours of sunlight are relatively long, the user normally operates the circuit breakers 10 and 40 to be kept in the off state and the switch 20 to be kept in the open state. As a result, the power conversion device 100 is supplied with power only from the photovoltaic power source PPS or the commercial power source CPS.

In this case, the control device 150 can recognize that only the power of the solar power source PPS is being supplied to the power conversion device 100 based on the state in which the above-mentioned first detection signal is not being input. Therefore, as shown in FIG. 4, the control device 150 controls the inverter circuit 130 so that the efficiency of power utilization of the solar power source PPS is relatively high (state S1).

For example, the control device 150 may use the inverter circuit 130 to perform MPPT control on the solar power generation power source PPS. As a result, the control device 150 can relatively increase the efficiency of power utilization of the solar power generation power source PPS by relatively increasing the power generation efficiency of the solar power generation power source PPS. Also, for example, the control device 150 may control the inverter circuit 130 to relatively increase the conversion efficiency from the power input of the solar power generation power source PPS to three-phase AC power for driving the electric motor M. As a result, the control device 150 can relatively increase the efficiency of power utilization of the solar power generation power source PPS by relatively increasing the conversion efficiency from the power input of the solar power generation power source PPS to three-phase AC power for driving the electric motor M.

In addition, in this example, when the weather at the installation location of the photovoltaic power source PPS worsens or when sufficient sunshine hours cannot be secured, the user may switch the circuit breakers 10, 40 and the switch 20 to the closed state. As a result, in addition to the power from the photovoltaic power source PPS, power from the commercial power source CPS is additionally input to the power conversion device 100 (state transition ST1). Therefore, even in a situation where it is difficult to stably drive the motor M with only the power from the photovoltaic power source PPS, the power conversion device 100 can stably drive the motor M with the power from the commercial power source CPS.

In this case, the control device 150 can recognize the additional input of power from the commercial power source CPS to the power conversion device 100 based on the start of input of the first detection signal. Then, as shown in FIG. 4, the control device 150 prioritizes the efficiency of the power usage of the photovoltaic power source PPS and the commercial power source CPS. Specifically, the control device 150 stops control (e.g., MPPT control) that relatively increases the efficiency of the power usage of the photovoltaic power source PPS, and controls the operation of the inverter circuit 130 so that the efficiency of the power usage of the commercial power source CPS becomes relatively high (state S2). This allows the control device 150 to increase the overall efficiency of the power usage of the photovoltaic power source PPS and the commercial power source CPS. This is because, in a situation where the weather at the installation site of the photovoltaic power source PPS worsens or the amount of sunlight cannot be relatively secured, the amount of power supplied from the photovoltaic power source PPS decreases, and the amount of power supplied from the commercial power source CPS becomes relatively greater.

For example, the control device 150 may control the inverter circuit 130 so that, under a specified operating condition of the motor M, the conversion efficiency from the power input of the commercial power source CPS to the three-phase AC power for driving the motor M is relatively high (e.g., maximized). This allows the control device 150 to relatively increase the efficiency of power utilization of the commercial power source CPS.

In addition, in this example, when the weather at the installation location of the photovoltaic power source PPS improves or improves to the point where sufficient sunshine hours can be secured, the user may switch the circuit breakers 10 and 40 to the cutoff state and the switch 20 to the open state. This cuts off the power supply from either the photovoltaic power source PPS or the commercial power source CPS, and the power conversion device 100 is supplied with only the power from the photovoltaic power source PPS (state transition ST2).

In this case, the control device 150 can recognize the interruption of the power supply from the commercial power source CPS to the power conversion device 100 based on the stop of the input of the first detection signal. Then, as shown in FIG. 4, the control device 150 immediately switches the control of the inverter circuit 130 from a mode that relatively increases the efficiency of the power usage of the commercial power source CPS to a mode that relatively increases the efficiency of the power usage of the solar power generation power source PPS (state S2 → state S1). As a result, even if the power supply from the commercial power source CPS is interrupted, the power conversion device 100 can continue to reliably output the required power to the electric motor M based on the solar power generation power source PPS. Therefore, the power conversion device 100 can maintain a stable and efficient power supply to the electric motor M when the power supply from the commercial power source CPS, which is one of the solar power generation power source PPS and the commercial power source CPS, is interrupted.

For example, when the control device 150 recognizes that the power supply from the commercial power source CPS to the power conversion device 100 has been cut off, it immediately starts MPPT control of the photovoltaic power source PPS (solar cell SC) using the inverter circuit 130. This allows the power conversion device 100 to receive more power from the photovoltaic power source PPS and continue to output the power required to drive the motor M to the motor M without interruption.

<Second example of control method>
In this example (second example), unlike the first example described above, there are cases where power is supplied to the power conversion device 100 only from the commercial power source CPS out of the photovoltaic power source PPS and the commercial power source CPS. Also, in this example, unlike the first example described above, the control device 150 can detect the presence or absence of power supply from each of the photovoltaic power source PPS and the commercial power source CPS to the power conversion device 100 based on the presence or absence of input of the second detection signal and the third detection signal. Below, the following description will focus on the parts that are different from the first example described above, and the description of the same or corresponding parts may be simplified or omitted.

In this example, when a situation occurs in which power cannot be supplied from the photovoltaic power source PPS, the user may operate the circuit breakers 10, 40 and the switch 20 to keep them closed, and the circuit breaker 30 to switch to the cut-off state. Situations in which power cannot be supplied from the photovoltaic power source PPS may include, for example, situations in which the amount of power generated is nearly zero, such as at night, or situations in which an abnormality occurs. As a result, the power conversion device 100 is cut off from the power supply from either the photovoltaic power source PPS or the commercial power source CPS, and is placed in a state in which only power from the commercial power source CPS is supplied (state transition ST3).

In this case, the control device 150 can recognize the continuation of the power supply from the commercial power source CPS to the power conversion device 100 based on the continued input of the third detection signal. Also, the control device 150 can recognize the interruption of the power supply from the photovoltaic power source PPS to the power conversion device 100 based on the cessation of the input of the second detection signal. Then, as shown in FIG. 4, the control device 150 continues the state of controlling the operation of the inverter circuit 130 so that the efficiency of the power utilization of the commercial power source CPS is relatively high (state S2 → state S3). This allows the power conversion device 100 to maintain a state in which the electric motor M is driven stably and efficiently.

In addition, in this example, when the situation improves to the point where power can be supplied from the photovoltaic power source PPS, the user may switch the circuit breaker 30 to the closed state while the circuit breakers 10, 40 and the switch 20 remain in the closed state. As a result, the power conversion device 100 is supplied with additional power from the photovoltaic power source PPS in addition to the power from the commercial power source CPS (state transition ST4).

In this case, the control device 150 can recognize the continuation of the power supply from the commercial power source CPS to the power conversion device 100 based on the continued input of the third detection signal. Also, the control device 150 can recognize the switching of the circuit breaker 30 to the closed state, i.e., the additional input of power from the photovoltaic power source PPS to the power conversion device 100, based on the start of the input of the second detection signal. Then, as shown in FIG. 4, the control device 150 continues the state of controlling the operation of the inverter circuit 130 so that the efficiency of the power utilization of the commercial power source CPS is relatively high (state S3 → state S2). This allows the power conversion device 100 to maintain a state in which the electric motor M is driven stably and efficiently.

<Third example of control method>
In this example, the power is automatically turned on and off from the two power sources, the photovoltaic power source PPS and the commercial power source CPS, to the power conversion device 100. That is, the circuit breakers 10, 30 and the switch 20 automatically switch their states in response to control signals from the outside. The switching of the states of the circuit breakers 10, 30 and the switch 20 may be performed by the control device 150, or may be performed by another control device different from the control device 150. In addition, in this example, the detection circuit 50 is omitted. This is because the control device 150 can control the states of the circuit breakers 10, 30 and the switch 20 by itself, or receive signals related to the control states of the circuit breakers 10, 30 and the switch 20 from another control device. Hereinafter, the parts different from the first example and the like described above will be mainly described, and the description of the same or corresponding parts may be simplified or omitted.

In this example, the explanation will be focused on the case where the control device 150 controls the automatic supply and cut-off of power to the power conversion device 100 from two power sources, a solar power source PPS and a commercial power source CPS.

The control device 150 may input only the power of the photovoltaic power source PPS and the commercial power source CPS to the power conversion device 100 when the weather at the installation location of the photovoltaic power source PPS is good or the sunshine hours can be secured relatively long. Specifically, when the output power or power generation amount of the photovoltaic power source PPS is relatively high or is predicted to be relatively high, the control device 150 may keep the circuit breaker 30 in the closed state and the circuit breaker 10 and the switch 20 in the interrupted state and open state, respectively. For example, the control device 150 may determine whether the output power or power generation amount of the photovoltaic power source PPS is relatively high based on the measured value of the output power of the photovoltaic power source PPS when the MPPT control is performed. In addition, for example, the control device 150 may determine whether the output power or power generation amount of the photovoltaic power source PPS is relatively high based on the measured value of the amount of solar radiation by a predetermined sensor or the like installed at the installation location of the photovoltaic power source PPS or information on the weather and sunshine hours obtained from an external device. Information about weather and sunshine hours obtained from an external device includes, for example, weather information obtained from a weather server.

In addition, when the weather at the installation location of the photovoltaic power source PPS worsens or when sufficient sunshine hours cannot be secured, the control device 150 may supply power from the commercial power source CPS to the power conversion device 100 in addition to the power from the photovoltaic power source PPS (state transition ST1). Specifically, when the output power or power generation amount of the photovoltaic power source PPS becomes relatively low, or when this is predicted, the control device 150 may switch the circuit breaker 10 and the switch 20 to the closed state while maintaining the circuit breaker 30 in the closed state.

In addition, when the weather at the installation location of the photovoltaic power source PPS improves or improves to the point where sufficient sunshine hours can be secured, the control device 150 may cut off power from the commercial power source CPS and switch to a state in which power is supplied to the power conversion device 100 only from the photovoltaic power source PPS (state transition ST2). Specifically, when the output power or power generation amount of the photovoltaic power source PPS becomes relatively high, or when this is predicted, the control device 150 may switch the circuit breaker 10 and the switch 20 to the cut-off state and the open state, respectively, while maintaining the circuit breaker 30 in the closed state.

In addition, when power cannot be supplied from the solar power source PPS, the control device 150 may cut off the power input from the solar power source PPS and switch to a state in which power is input to the power conversion device 100 only from the commercial power source CPS (state transition ST3). Specifically, when the output power or power generation amount of the solar power source PPS becomes approximately zero, the control device 150 may switch the circuit breaker 30 to the cut-off state while keeping the circuit breaker 10 and the switch 20 in the closed state.

When the situation improves to the point where power can be supplied from the photovoltaic power source PPS, the control device 150 may supply power from the photovoltaic power source PPS to the power conversion device 100 in addition to the power from the commercial power source CPS (state transition ST4). Specifically, when the output voltage or power generation amount of the photovoltaic power source PPS is no longer approximately zero, the control device 150 may switch the circuit breaker 30 to the closed state while maintaining the circuit breaker 10 and the switch 20 in the closed state.

In this way, the control device 150 can switch on and off the photovoltaic power source PPS and the commercial power source CPS according to the state of the output power and power generation amount of the photovoltaic power source PPS. This allows the power conversion device 100 to drive the electric motor M more stably and efficiently using the power from the photovoltaic power source PPS and the commercial power source CPS under the control of the control device 150.

[Other embodiments]
The configurations and control methods of the above-described embodiments may be modified or changed as appropriate.

For example, in the above-described embodiment, the power conversion device 100 may drive a load device other than the motor M using power from the solar power source PPS and the commercial power source CPS. The load device may be, for example, a fluorescent lamp (an example of a specified load device).

For example, the power conversion device 100 may also include a built-in circuit for detecting interruption of power supply from the AC input unit ACIN or the DC input unit DCIN, a circuit for detecting the DC link voltage, etc. In this case, the control device 150 determines whether or not power is being supplied to the power conversion device 100 from each of the photovoltaic power source PPS and the commercial power source CPS based on the detection signals of these detection circuits, and the detection circuit 50 may be omitted. This makes it possible to reduce the overall cost and space of the electric motor drive system 1.

In addition, for example, in the above-mentioned embodiment and its modified and altered examples, when power is supplied to the power conversion device 100 from both the photovoltaic power source PPS and the commercial power source CPS, the control device 150 may vary which power source is prioritized in terms of efficiency of power usage. For example, when the circuit breakers 10, 40 and the switch 20 are manually operated, even in a situation where additional power is input from the commercial power source CPS, the amount of power input from the photovoltaic power source PPS may actually be greater than the amount of power input from the commercial power source CPS.

In addition, some or all of the functions of the control device 150 may be arranged outside the power conversion device 100 in a manner that allows communication with the power conversion device 100 through a predetermined communication line. For example, some or all of the functions of the control device 150 may be realized by a server device that can communicate with the power conversion device 100. In this case, the server device may be, for example, a cloud server installed in a management center or the like other than the facility in which the power conversion device 100 and the load device (for example, the electric motor M) are installed. In addition, the server device may be, for example, an edge server installed in the facility in which the power conversion device 100 and the load device are installed, or in a location relatively close to the facility (for example, a communication facility such as a base station or station building in the vicinity of the facility). In addition, some or all of the functions of the control device 150 may be realized by a computer terminal in the facility in which the power conversion device 100 and the load device are installed.

[Action]
Next, the operation of the power conversion device 100 (control device 150) according to this embodiment will be described.

In this embodiment, the power conversion device 100 includes a DC input unit DCIN to which DC power from a photovoltaic power source PPS can be input, and an AC input unit ACIN to which AC power from a commercial power source CPS can be input. The power conversion device 100 also includes an inverter circuit 130 that converts the power input from at least one of the two power sources, the photovoltaic power source PPS and the commercial power source CPS, into a predetermined AC power and drives a predetermined load device.

For example, in the above-mentioned Patent Document 1, a load device is driven using power from a solar power generation system and a commercial power supply system by multiple power conversion devices (AC-DC converter, DC-DC converter, and DC-AC converter). Therefore, the overall conversion efficiency of the multiple power conversion devices is relatively reduced, which may result in a relative deterioration in the efficiency of power usage by the solar power generation system and the commercial power supply system.

In contrast, in this embodiment, a single power conversion device 100 (inverter circuit 130) can be used to drive a load device using power from a solar power generation power source PPS and a commercial power source CPS. Therefore, the power conversion device 100 can improve the overall efficiency of power usage when driving a load device using the solar power generation power source PPS and the commercial power source CPS.

In addition, in this embodiment, the inverter circuit 130, under the control of the control device 150, shifts its operation in response to changes in the power input conditions from the two power sources so that it can drive the load device more stably and efficiently.

This allows the power conversion device 100 (control device 150) to realize optimal operation transitions from the perspective of stable and efficient driving of the load device in accordance with changes in the input conditions of power from each of the photovoltaic power source PPS and the commercial power source CPS. Therefore, the power conversion device 100 (control device 150) can stably and efficiently drive the load device using power from the photovoltaic power source PPS and the commercial power source CPS.

In addition, in this embodiment, when power is input from the commercial power source CPS in a state in which power is input only from the photovoltaic power source PPS of the two power sources, the inverter circuit 130, under the control of the control device 150, shifts its operation to prioritize the second efficiency from the input of power from the commercial power source CPS to the conversion to the specified AC power over the first efficiency from the generation of power by the photovoltaic power source PPS to the conversion to the specified AC power.

As a result, the power conversion device 100 (control device 150) can stably drive the load device with the power of the commercial power source CPS regardless of the input status of the power from the photovoltaic power source PPS by additionally inputting the power from the commercial power source CPS in addition to the power from the photovoltaic power source PPS. Also, when the power from the commercial power source CPS is additionally input in addition to the power from the photovoltaic power source PPS, the power conversion device 100 (control device 150) can relatively increase the efficiency of the overall power utilization of the photovoltaic power source PPS and the commercial power source CPS. This is because, in a situation where the power of the commercial power source CPS is additionally input in addition to the power from the photovoltaic power source PPS, the output power of the photovoltaic power source PPS becomes relatively low, and the power input from the commercial power source CPS to the power conversion device 100 is likely to be larger. Therefore, in a situation where the power from the commercial power source CPS is additionally input in addition to the power from the photovoltaic power source PPS, the power conversion device 100 (control device 150) can stably and efficiently drive the load device using the power from the photovoltaic power source PPS and the commercial power source CPS.

In addition, in this embodiment, the inverter circuit 130 may perform MPPT control under the control of the control device 150 to track the operating point of the solar cell SC included in the solar power generation power source PPS so that the output power of the solar cell SC is maximized in a state in which power is input only from the solar power generation power source PPS out of the two power sources. On the other hand, the inverter circuit 130 may stop MPPT control when power from the commercial power source CPS is input in addition to power from the solar power generation power source PPS.

As a result, the power conversion device 100 (control device 150) can maximize the power generation efficiency of the solar power source PPS through MPPT control, and relatively increase the efficiency of power utilization from the solar power source PPS. Furthermore, when power from the commercial power source CPS is additionally input in addition to the power from the solar power source PPS, the power conversion device 100 (control device 150) can stop MPPT control and transition to control that prioritizes (relatively increases) the efficiency of power utilization from the commercial power source CPS.

In addition, in this embodiment, under the control of the control device 150, when power is input from both of the two power sources, the inverter circuit 130 operates to prioritize the second efficiency from the input of power from the commercial power source CPS to the conversion to a specified AC power over the first efficiency from the power generation by the photovoltaic power source PPS to the conversion to a specified AC power, and when the input of power from the commercial power source CPS is interrupted, the inverter circuit 130 shifts operation to increase the first efficiency.

As a result, the power conversion device 100 (control device 150) can stably drive the load device with the power of the commercial power source CPS regardless of the input status of the power from the photovoltaic power source PPS by inputting the power of both the photovoltaic power source PPS and the commercial power source CPS. In addition, the power conversion device 100 (control device 150) can relatively increase the efficiency of the overall power utilization of the photovoltaic power source PPS and the commercial power source CPS in a situation where the power of both the photovoltaic power source PPS and the commercial power source CPS is input. This is because, in a situation where the power of the commercial power source CPS is input in addition to the power of the photovoltaic power source PPS, the output power of the photovoltaic power source PPS becomes relatively low, and the power input from the commercial power source CPS to the power conversion device 100 is likely to be larger. In addition, the power conversion device 100 (control device 150) can stably and efficiently supply the required power to the load device by relatively increasing the efficiency (first efficiency) of the power utilization of the photovoltaic power source PPS in a situation where the power from the commercial power source CPS is cut off. Therefore, when switching from a state in which power is supplied from the photovoltaic power source PPS and the commercial power source CPS to a state in which only power from the former is supplied, the power conversion device 100 (control device 150) can stably and efficiently drive the load device using power from the two power sources.

In addition, in this embodiment, under the control of the control device 150, when the input of power from the commercial power source CPS is cut off in a state in which power is input from both of the two power sources, the inverter circuit 130 optimally starts MPPT control to track the operating point of the solar cell SC included in the photovoltaic power source PPS so that the output power of the solar cell SC is maximized.

For example, if the previous control state of the inverter circuit 130 is maintained when the power input from the commercial power source CPS is cut off, the efficiency of power utilization of the photovoltaic power source PPS may relatively decrease. In addition, the operating point (output voltage) of the photovoltaic power source PPS (solar cell SC) may not be appropriately controlled, and therefore sufficient power may not be input. As a result, for example, an abnormality may be detected by the abnormality detection function of the power conversion device 100, causing the power conversion device 100 to stop or a momentary interruption in the power supply from the power conversion device 100 to the load device.

In contrast, in this embodiment, the power conversion device 100 (control device 150) can quickly start MPPT control for the photovoltaic power source PPS (solar cell SC) when the power input from the commercial power source CPS is cut off. Therefore, the power conversion device 100 can relatively increase the efficiency of power utilization of the photovoltaic power source PPS and efficiently drive the load device. In addition, the power conversion device 100 (control device 150) inputs a sufficient amount of power from the photovoltaic power source PPS (solar cell SC), suppressing abnormal shutdown of the device itself and momentary interruption of the power supply to the load device, and can stably drive the load device.

In addition, in this embodiment, the inverter circuit 130, under the control of the control device 150, shifts its operation so that it can drive the load device more stably and efficiently in accordance with the input and cutoff of power from each of the two power sources, the photovoltaic power source PPS and the commercial power source CPS.

This allows the power conversion device 100 to realize optimal operation transitions from the perspective of stable and efficient drive of the load device in accordance with the input and cutoff of power from each of the two power sources, the solar power generation power source PPS and the commercial power source CPS. Therefore, the power conversion device 100 (control device 150) can stably and efficiently drive the load device using power from the solar power generation power source PPS and the commercial power source CPS.

Although the embodiments have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the invention as described in the claims.

REFERENCE SIGNS LIST 1 Motor drive system 10 Circuit breaker 10_S Switch 20 Switch 20_C Coil section 20_S Switch 30 Circuit breaker 30_S Switch 40 Circuit breaker 50 Detection circuit 51 Transformer 52 to 56 Circuit section 100 Power conversion device 110 Rectifier circuit 120 Smoothing circuit 122 Smoothing capacitor 124 Reactor 130 Inverter circuit (load drive section)
140 Charging circuit 142 Switch 144 Charging resistor 150 Control device ACIN AC input section (second input section)
ACOUT AC output section AC_IL AC input line AC_OL AC output line BPD Diode CPS Commercial power supply CPS_C Coil section DCIN DC input section (first input section)
DC_IL DC input line G Ground terminal LT1, LT2 Reactor connection terminal M Motor (load device)
N Negative DC terminal NL Negative line N_IL Negative input line P Positive DC terminal PL Positive line PPS Photovoltaic power source PPS_C Coil section PS_C Coil section PW_C Coil section PW_S Switch P_IL Positive input line R, S, T AC input terminals R_IL R-phase input line S_IL S-phase input line SC Solar cell T_IL T-phase input line U, V, W AC output terminals U_OL U-phase output line V_OL V-phase output line W_OL W-phase output line

Claims (6)

A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least one of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
the load driving unit selects either a first operation for improving the efficiency of power utilization of the solar power generation power source of the two power sources or a second operation for improving the efficiency of power utilization of the commercial power source of the two power sources in response to a change in the input status of power from the two power sources among a first state in which power is input only from the solar power generation power source of the two power sources, a second state in which power is input from both the solar power generation power source and the commercial power source of the two power sources, and a third state in which power is input only from the commercial power source of the two power sources, thereby transitioning the operation so as to drive the load device more stably and more efficiently.
Power conversion equipment. A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least the solar power source of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
when power is input from the commercial power source in a state in which power is input only from the solar power generation power source of the two power sources, the load driving unit shifts its operation so as to prioritize a second efficiency from the input of power from the commercial power source to the conversion of power into the specified AC power over a first efficiency from the power generation of the solar power generation power source to the conversion of power into the specified AC power.
Power conversion equipment. the load driving unit performs maximum power point tracking control for tracking an operating point of the solar cell included in the solar power generation power supply so that an output power of the solar cell is maximized in a state where power is input only from the solar power generation power supply of the two power supplies, and stops the maximum power point tracking control when power from the commercial power supply is input.
The power conversion device according to claim 2 . A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least the solar power source of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
the load driving unit operates, in a state in which power is input from both of the two power sources, to prioritize a second efficiency from the input of power from the commercial power source to the conversion of the power into the specified AC power over a first efficiency from the power generation of the photovoltaic power source to the conversion of the power into the specified AC power, and when the input of power from the commercial power source is interrupted, shifts its operation to enhance the first efficiency.
Power conversion equipment. when the input of power from the commercial power source is cut off in a state in which power is being input from both of the two power sources, the load driving unit starts maximum power point tracking control for tracking an operating point of the solar cell included in the photovoltaic power generation power source so that an output power of the solar cell is maximized.
The power conversion device according to claim 4. A first input unit to which DC power from a solar power generation power source can be input;
a second input unit to which AC power from a commercial power source can be input;
a load driving unit that converts power input from at least one of the two power sources, the solar power source and the commercial power source, into a predetermined AC power and drives a predetermined load device;
the load driving unit selects either a first operation for improving the efficiency of power usage of the solar power generation power source of the two power sources, or a second operation for improving the efficiency of power usage of the commercial power source of the two power sources, in accordance with the input and cut-off of power from one of the two power sources while power input from the other power source is continuing, thereby shifting the operation so as to drive the load device more stably and more efficiently;
Power conversion equipment.

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