Power control device, power control method, and storage medium

Abstract

To provide a power control device, etc. which can expand the applicable voltage range while suppressing an increase in the size of a limiting resistor.SOLUTION: An inverter device 10 comprises: an indicator element 30 which is provided between a high potential line and a low potential line that provide power controlled by the inverter device 10, and which indicates a state of the inverter device 10 according to a flowing current; and resistance variation parts 151 and 152 which are connected in series with the indicator element 30 between the high potential line and the low potential line, and which vary their resistance values according to the voltage between the high potential line and the low potential line. The resistance values of the resistance variation parts 151 and 152 at least include: a low-voltage-side resistance value when the voltage is lower than a predetermined intermediate voltage; and a high-voltage-side resistance value, which is greater than the low-voltage-side resistance value, when the voltage is higher than the intermediate voltage.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a power control device and the like. [Background technology]

[0002] Patent Document 1 discloses an inverter device as a power control device. This inverter device converts RST three-phase AC power supplied from an AC power supply into UVW three-phase AC power for driving a three-phase motor.

[0003] A typical inverter device is equipped with a smoothing capacitor that smoothes out the direct current or pulsating current generated in the process of converting AC power. Immediately after the inverter device stops operating, a large amount of charge may be stored in the smoothing capacitor. For safety reasons, it is required to indicate the presence or absence of such residual charge by an indicator element such as an LED. In addition, a resistor, sometimes referred to as a limiting resistor, is connected in series to the indicator element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-171100 A Summary of the Invention [Problem to be solved by the invention]

[0005] The indicator element must perform an operation such as lighting to indicate the residual charge even when the DC voltage due to the residual charge is a predetermined lower limit voltage (e.g., about 60 V). Also, even when the DC voltage due to the residual charge is a predetermined upper limit voltage (e.g., about 700 V), the amount of heat generated per unit surface area or unit volume of the limiting resistor must be kept below a specified amount. To simultaneously satisfy these two conditions (especially the second condition regarding the amount of heat generated), the surface area or volume of the limiting resistor must be increased, which would result in an increase in the size of the limiting resistor and, ultimately, the inverter device.

[0006] The present disclosure has been made in consideration of these circumstances, and has an object to provide a power control device and the like that can expand the compatible voltage range while suppressing an increase in the size of the limiting resistor. [Means for solving the problem]

[0007] In order to solve the above problems, a power control device according to one embodiment of the present disclosure includes an indicator element provided between a high potential line and a low potential line that provide power controlled by the power control device, and indicating the state of the power control device in response to a current flowing therethrough, and a resistance change unit connected in series with the indicator element between the high potential line and the low potential line, the resistance change unit changing its resistance value in response to the voltage between the high potential line and the low potential line.

[0008] In this embodiment, the resistance value of the resistance change section changes depending on the voltage handled by the power control device. For example, when the voltage increases, the resistance value is increased to suppress the current and suppress the amount of heat generated in the resistance change section. Therefore, there is less need to enlarge the resistance change section that functions as a limiting resistor in order to dissipate heat.

[0009] Another aspect of the present disclosure is a power control method, which includes a power control device including an indicator element provided between a high potential line and a low potential line that provide power controlled by the power control device and indicating a state of the power control device in response to a current flowing therethrough, and a resistance change unit connected in series to the indicator element between the high potential line and the low potential line, and which changes a resistance value in the resistance change unit in response to a voltage between the high potential line and the low potential line.

[0010] Yet another aspect of the present disclosure is a storage medium, the storage medium storing a power control program for causing a computer to execute a control operation for a power control device including an indicator element provided between a high potential line and a low potential line that provide power controlled by the power control device and indicating a state of the power control device in response to a current flowing therethrough, and a resistance change unit connected in series to the indicator element between the high potential line and the low potential line, the power control device including an indicator element and a resistance change unit that are connected in series to the indicator element between the high potential line and the low potential line.

[0011] Any combination of the above components, or any conversion of these components into a method, device, system, recording medium, computer program, or the like, is also encompassed by the present disclosure. Effect of the Invention

[0012] According to the present disclosure, it is possible to expand the range of compatible voltages while suppressing an increase in the size of a limiting resistor in a power control device or the like. [Brief description of the drawings]

[0013] [Figure 1] 1 shows a schematic diagram of an overall configuration of an inverter device. [Diagram 2] FIG. 2 is a diagram illustrating details of the inverter device of FIG. [Diagram 3] 3 is a schematic graph of the current passed through the indicator element through the indicator control circuit shown in FIG. 2; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In the following, the form for carrying out the present disclosure (hereinafter, also referred to as an embodiment) will be described in detail with reference to the drawings. In the description and / or drawings, the same or equivalent components, members, processes, etc. will be given the same reference numerals, and duplicated descriptions will be omitted. The scale and shape of each part shown in the drawings are set for convenience in order to simplify the description, and are not to be interpreted as being limiting unless otherwise specified. The embodiment is an example, and does not limit the scope of the present disclosure in any way. All features and their combinations presented in the embodiment are not necessarily essential to the present disclosure. The embodiment is presented by decomposing it into components for each function and / or each functional group that realizes it for convenience. However, one component in the embodiment may be realized by a combination of multiple components that are actually separate, or multiple components in the embodiment may be realized by one component that is actually integrated. In addition, multiple embodiments and variations may be disclosed in parallel, but any components of each embodiment and / or each variation may be combined in any manner as long as they do not inhibit each other's functions.

[0015] 1 is a schematic diagram showing an overall configuration of an inverter device 10 according to the present embodiment as an example of a power control device according to the present disclosure. The inverter device 10 includes a converter 11 that rectifies three-phase AC, i.e., R-phase, S-phase, and T-phase, supplied from a commercial power source or the like, and converts it into DC (pulsating current), a smoothing capacitor 12 that smoothes the DC converted by the converter 11 to shape the waveform, and an inverter 13 that converts the DC smoothed by the smoothing capacitor 12 into AC.

[0016] The converter 11 includes diodes 111 to 116 that rectify three-phase (R, S, T) AC current supplied from a commercial power source or the like in a fixed direction (from bottom to top in the figure). The diode 111 passes a current when the R-phase AC voltage is positive, the diode 112 passes a current when the R-phase AC voltage is negative, the diode 113 passes a current when the S-phase AC voltage is positive, the diode 114 passes a current when the S-phase AC voltage is negative, the diode 115 passes a current when the T-phase AC voltage is positive, and the diode 116 passes a current when the T-phase AC voltage is negative. The diodes 111 to 116 connected in a bridge shape in this way cause a pulsating current with a fixed direction and varying magnitude to appear between the output terminals of the converter 11. The smoothing capacitor 12 supplies a direct current that has been smoothed from the pulsating current obtained by the converter 11 to the inverter 13.

[0017] In the following, a DC voltage input between a high potential input terminal 131 and a low potential input terminal 132 of an inverter 13 via a converter 11 and a smoothing capacitor 12 is referred to as V DC The potential of the high potential line to which the high potential input terminal 131 is connected is represented as V dd , the potential of the low potential line to which the low potential input terminal 132 is connected is V ss Then, V DC =V dd -V ss It is.

[0018] The inverter 13 outputs a high-voltage DC dd The high-potential line that supplies the DC ss In other words, the inverter 13 outputs a three-phase AC voltage V input between a high potential input terminal 131 and a low potential input terminal 132 by switching operations of three-phase transistor pairs of U-phase, V-phase, and W-phase that are connected in parallel between the low potential lines that supply the DC voltage V DC Specifically, a three-phase AC voltage is generated based on the DC voltage V DC and a U-phase inverter 13U that generates a U-phase AC voltage based on DC A V-phase inverter 13V generates a V-phase AC current based on DCA W-phase inverter 13W that generates a W-phase AC based on the above is provided in parallel. Since the inverters 13U, 13V, and 13W of each phase have a common configuration, they will be collectively referred to as inverter 13 as appropriate and described below.

[0019] The inverter 13 is connected to a high DC power supply potential V dd A high-potential input terminal 131 to which a low DC power supply potential V ss A low potential input terminal 132 to which V is input is provided between the high potential input terminal 131 and the low potential input terminal 132. dd and V ss and an AC output terminal 133 that outputs an AC voltage that fluctuates between a high potential line and the AC output terminal 133. A high potential side transistor 134H is connected between the high potential line and the AC output terminal 133 as a high potential side switching element, and a low potential side transistor 134L is connected between the low potential line and the AC output terminal 133 as a low potential side switching element.

[0020] The high-side transistor 134H performs a switching operation to switch the conductive state of the current path in response to a pulse (high-side control signal) supplied from a high-side driver 135H connected to its control terminal as a driver. The low-side transistor 134L performs a switching operation to switch the conductive state of the current path in response to a pulse (low-side control signal) supplied from a low-side driver 135L connected to its control terminal as a driver. In the following, the high-side transistor 134H and the low-side transistor 134L are collectively referred to as transistor 134 or transistor pair 134 as appropriate, and the high-side driver 135H and the low-side driver 135L are collectively referred to as driver 135 or driver pair 135 as appropriate. In the following description, "H" meaning "high side" and "L" meaning "low side" are omitted as appropriate, but "H" and "L" are added to the end of the symbols as necessary in the drawings.

[0021] In the illustrated example, the transistor 134 is an insulated gate bipolar transistor (IGBT) having a gate 31 as a control terminal, a collector 32 as a high potential side terminal connected to the high potential line side, and an emitter 33 as a low potential side terminal connected to the low potential line side. However, the transistor 134 or the switching element may be a field effect transistor (FET) having a gate as a control terminal, a drain as a high potential side terminal, and a source as a low potential side terminal, or may be a bipolar transistor having a base as a control terminal, a collector as a high potential side terminal, and an emitter as a low potential side terminal.

[0022] In the high-side transistor 134H, the gate 31H is connected to the high-side driver 135H, the collector 32H is connected to the high-side input terminal 131 or the high-side line, and the emitter 33H is connected to the AC output terminal 133 and the collector 32L of the low-side transistor 134L. In the low-side transistor 134L, the gate 31L is connected to the low-side driver 135L, the collector 32L is connected to the AC output terminal 133 and the emitter 33H of the high-side transistor 134H, and the emitter 33L is connected to the low-side input terminal 132 or the low-side line. In the above configuration, the connection point of the emitter 33H of the high-side transistor 134H and the collector 32L of the low-side transistor 134L forms the AC output terminal 133.

[0023] In each transistor 134, the current path or channel between the collector 32 and the emitter 33 switches its conductive state in response to a pulse (control signal) applied from each driver 135 to the gate 31. A protection diode 34 may be provided in parallel with this current path or channel as a protection diode element. The protection diode 34 may be a discrete element separate from the transistor 134, or may be formed integrally or monolithically with the transistor 134 in the semiconductor manufacturing process for manufacturing the transistor 134. The protection diode 34 is provided so as to pass a current only in the direction from the low potential line side to the high potential line side.

[0024] The driver 135, which may be configured as an integrated circuit (IC), supplies a switching pulse as a control signal for a switching operation to the gate 31 of the transistor 134. For example, the driver 135 applies a pulse whose duty ratio or pulse width is controlled by PWM (Pulse Width Modulation) to the gate 31 of the transistor 134. The transistor 134 performs a switching operation in which it switches between an on state and an off state depending on the presence or absence of a pulse. Specifically, while a pulse is applied to the gate 31, the transistor 134 is in an on state, and a channel between the collector 32 and the emitter 33 is in a conductive state. Meanwhile, while a pulse is not applied to the gate 31, the transistor 134 is in an off state, and a channel between the collector 32 and the emitter 33 is in a non-conductive state.

[0025] The driver 135 of each phase converts DC to AC of each phase by performing switching control to complementarily switch the conductive state of the transistor pair composed of the high potential side transistor 134H and the low potential side transistor 134L under the control of a control unit (not shown). Here, "complementarily switching" means controlling so that the transistor pairs of each phase are not simultaneously turned on. In other words, when one transistor in each phase is turned on, the other transistor in the phase is controlled to be turned off. However, it is permitted that the transistor pairs of each phase are simultaneously turned off. In addition, the high potential side control signal for the high potential side transistor 134H and the low potential side control signal for the low potential side transistor 134L, which are in the above-mentioned relationship, are expressed as being "complementary" to each other.

[0026] Specifically, for the U phase, when the high potential side transistor 134H is in the ON state, the low potential side transistor 134L is controlled to be in the OFF state, and when the low potential side transistor 134L is in the ON state, the high potential side transistor 134H is controlled to be in the OFF state. Therefore, when the high potential side transistor 134H is in the ON state, a high potential V dd appears, and when the low-potential side transistor 134L is in the ON state, a low potential V ss By periodically repeating such switching control, a high potential V appears at the U-phase AC output terminal 133U. dd and low potential V ss A U-phase alternating current is generated in which

[0027] The three-phase AC generated by the inverter 13 as described above is supplied to the motor 20 that generates rotational power. The motor 20 is, for example, a three-phase brushless motor equipped with three-phase coils 20U, 20V, and 20W of U-phase, V-phase, and W-phase. A U-phase current flows from an AC output terminal 133U of the U-phase inverter 13U to the U-phase coil 20U, a V-phase current flows from an AC output terminal 133V of the V-phase inverter 13V to the V-phase coil 20V, and a W-phase current flows from an AC output terminal 133W of the W-phase inverter 13W to the W-phase coil 20W. The inverters 13U, 13V, and 13W of each phase apply three-phase ACs of different phases to the coils 20U, 20V, and 20W of each phase based on the rotational position of the rotor (not shown) detected by the hall elements H1, H2, and H3 of the motor 20 to generate a rotating magnetic field. A desired rotational power is obtained from the rotor that rotates by this rotating magnetic field. Note that motor 20 may be another type of motor driven by AC. The number of phases of motor 20 is not limited to three and may be any natural number. Similarly, the number of phases of the AC input to converter 11 is not limited to three and may be any natural number.

[0028] Fig. 2 is a diagram showing details of the inverter device 10 shown in Fig. 1. In this diagram, a voltage detection circuit 14 and an indicator control circuit 15 are provided in parallel with the smoothing capacitor 12 also shown in Fig. 1. Both the voltage detection circuit 14 and the indicator control circuit 15 are connected to a high potential V dd The high-voltage line and low-voltage V ss A voltage detection circuit 14 and / or an indicator control circuit 15 may be provided between the smoothing capacitor 12 and the inverter 13 (FIG. 1).

[0029] The voltage detection circuit 14 detects the DC voltage V between the high potential line and the low potential line. DC The voltage detection circuit 14 has voltage dividing resistors 141H and 141L connected between the high potential line and the low potential line, and an operational amplifier 142. The operational amplifier 142, which receives the connection point between the high potential side voltage dividing resistor 141H and the low potential side voltage dividing resistor 141L as its input, detects the DC voltage VDC Detect.

[0030] The indicator control circuit 15 is a circuit for controlling the indicator element 30. The indicator element 30 is a circuit for controlling the power or DC voltage V DC The indicator element 30 is provided between a high potential line and a low potential line that provide a DC voltage V DC Alternatively, it may be an element that indicates the residual charge of the smoothing capacitor 12 or any other state of the inverter device 10 based on any other principle (for example, sound).

[0031] The indicator element 30, which is constituted by a light emitting element such as an LED, is required to emit or light in a manner (for example, brightness) visible to humans. min Therefore, the DC voltage V due to the residual charge of the smoothing capacitor 12 DC However, at least the minimum current IF min If current cannot flow to the indicator element 30, the indicator element 30 will not emit light in a manner visible to humans to indicate the presence of such a residual charge.

[0032] Therefore, the indicator element 30 is required to have a rated voltage range or a lower limit voltage of a corresponding voltage range that the inverter device 10 should support (for example, a DC voltage V DC Even if the converter 11 is operated at a voltage of about 60 V (hereinafter, also referred to as DC60) or about 40 V (hereinafter, also referred to as AC40) as the AC voltage input to the converter 11, the residual charge corresponding to the lower limit voltage will be at least the minimum current IF minIn other words, immediately after the inverter device 10, which has been operating at a lower limit voltage such as DC60 or AC40, stops operating, the charge stored in the smoothing capacitor 12 must be able to flow at least a minimum current IF to the indicator element 30. min needs to flow.

[0033] The indicator control circuit 15 may include resistance change units 151 and 152 , a fixed resistor 153 , a Zener diode 154 , photocouplers 155 and 156 , and a buffer resistor 157 .

[0034] The resistance change units 151 and 152 function as limiting resistors connected in series to the indicator element 30 between the high potential line and the low potential line. DC The resistance value is changed according to the DC voltage V DC When the resistance value increases, the current is suppressed by increasing the resistance value, and the amount of heat generated in the resistance change portions 151 and 152 can be suppressed.

[0035] In order to make the resistance values ​​of the resistance change units 151 and 152 variable, a first resistor 151 and a second resistor 152 connected in parallel to each other are provided. As described later, the second resistor 152 is switched between a connected state and a disconnected state by photocouplers 155 and 156. Specifically, a DC voltage V DC When the DC voltage V is relatively low, the second resistor 152 is in a connected state, and therefore the combined resistance value of the first resistor 151 and the second resistor 152 connected in parallel becomes the resistance value of the resistance change units 151 and 152. DC is relatively high, the second resistor 152 is in a disconnected state, and so the resistance value of the first resistor 151, which is always in a connected state, becomes the resistance value of the resistance change units 151, 152. The combined resistance value of the first resistor 151 and the second resistor 152 at a low voltage is smaller than the individual resistance value of the first resistor 151 at a high voltage. In this way, the total resistance value of the resistance change units 151, 152 is DC The higher the value, the larger the

[0036] In order to realize the above-described change in resistance value, the resistance change units 151, 152 in the illustrated example have a first resistor 151 and a second resistor 152 connected in parallel to each other, but the resistance change units may be realized by a single variable resistor connected in series to the indicator element 30 instead. In this case, however, the DC voltage V DC A control circuit is required to adaptively change the resistance value of the variable resistor in accordance with the detection result.

[0037] Such an additional control circuit is expensive compared to simple elements such as the Zener diode 154 and the photocouplers 155 and 156 described below. Therefore, by adopting the configuration shown in the figure, the cost of the indicator control circuit 15 can be reduced. On the other hand, in the combination of the Zener diode 154 and the photocouplers 155 and 156, the DC voltage V DC However, in this embodiment, as described later, the current flowing through the indicator element 30 is set to a minimum current IF min and maximum current IF max Since it is sufficient to have the voltage between V DC Therefore, a low-cost configuration such as that shown in the figure is preferable.

[0038] The fixed resistor 153 connected in series to the indicator element 30 functions as a limiting resistor together with the resistance change sections 151 and 152. If the resistance change sections 151 and 152 alone can constitute a sufficient limiting resistor, the fixed resistor 153 does not need to be provided.

[0039] The Zener diode 154 is provided between the high potential line and the low potential line and is connected to the DC voltage V DC is a given intermediate voltage V in If the voltage is lower than X, no current flows, and the DC voltage V DC is the intermediate voltage V in When the intermediate voltage V is higher than X, it is a limiting element that passes current from the high potential side to the low potential side. inX is the breakdown voltage or Zener voltage of the Zener diode 154.

[0040] The Zener diode 154 may be directly connected between the high potential line and the low potential line together with a diode 155 on the primary side of a photocoupler described later, but is preferably connected in series with at least a part of the voltage dividing resistors 141H, 141L in the voltage detection circuit 14 on the high potential side as shown in Fig. 2. In the illustrated example, the high potential side of the Zener diode 154 is connected in series with a part 141H-1 on the further higher potential side of the high potential side voltage dividing resistor 141H. In this case, the Zener diode 154 is connected in parallel with a part 141H-2 on the low potential side of the high potential side voltage dividing resistor 141H and the low potential side voltage dividing resistor 141L.

[0041] In this way, the Zener diode 154 and the diode 155 on the primary side of the photocoupler described below can use or borrow the resistor 141H-1 required for their intended operation from the existing voltage detection circuit 14. Therefore, it is not necessary to provide a new resistor equivalent to the resistor 141H-1 in the indicator control circuit 15. However, an embodiment in which a new resistor equivalent to the resistor 141H-1 is provided in the indicator control circuit 15 is also included in the scope of the present disclosure.

[0042] Without being limited to the illustrated example, the high potential side of the Zener diode 154 may be connected in series with the entire high potential side voltage dividing resistor 141H (i.e., the connection point of the high potential side voltage dividing resistor 141H and the low potential side voltage dividing resistor 141L) depending on the resistance values ​​required by the Zener diode 154 and the diode 155, or may be connected in series with a part of the high potential side of the low potential side voltage dividing resistor 141L.

[0043] The buffer resistor 157 connected in series to the Zener diode 154 in the indicator control circuit 15 is a resistor for reducing the effect that the indicator control circuit 15 may have on the voltage detection circuit 14 when the primary side (Zener diode 154 and diode 155) of the indicator control circuit 15 is provided in addition to the existing voltage detection circuit 14. It is also possible to design both the voltage detection circuit 14 and the indicator control circuit 15 so that such undesirable effects or interactions between them do not occur, and in that case there is no need to provide the buffer resistor 157.

[0044] The photocouplers 155 and 156 are switching elements that switch the second resistor 152 between a connected state and a disconnected state. The photocouplers 155 and 156 are configured by a diode 155 on the primary side and a transistor 156 on the secondary side. The diode 155 on the primary side allows a current to flow substantially only in a direction from a high potential side to a low potential side. The current flowing through the diode 155 on the primary side is converted into an optical signal, which switches the transistor 156 on the secondary side between an on state and an off state. The switching element is not limited to a photocoupler, and may be configured by a solid state relay or the like.

[0045] The transistor 156 in the illustrated example is a so-called normally closed type, and is conductive (on) or closed when there is no optical signal from the primary-side diode 155. At this time, the second resistor 152 connected in series to the transistor 156 is connected. Also, when there is an optical signal from the primary-side diode 155, the transistor 156 is non-conductive (off) or open. At this time, the second resistor 152 connected in series to the transistor 156 is disconnected.

[0046] The Zener diode 154 described above functions as a switching signal generating unit that generates a switching signal for switching the photocouplers 155 and 156 or the transistor 156 as a switching element between a conductive state and a non-conductive state. DC is the intermediate voltage V inWhen the DC voltage V is lower than X, no current flows through the Zener diode 154, and therefore no current necessary for generating a switching signal flows through the diode 155 connected in series with the Zener diode 154. DC is the intermediate voltage V in When the DC voltage V is lower than V, the transistor 156 is in a conductive state. DC is the intermediate voltage V in When the DC voltage V is higher than X, a current flows through the Zener diode 154, and the current required to generate a switching signal also flows through the diode 155 connected in series with the Zener diode 154. DC is the intermediate voltage V in If it is above X, transistor 156 is non-conductive.

[0047] In this way, the second resistor 152 is connected to the DC voltage V DC is the intermediate voltage V in If it is lower than X, it will be in a conductive state, and the DC voltage V DC is the intermediate voltage V in A transistor 156 that is turned off when the input voltage is higher than X is connected in series. The total resistance value of the resistance change units 151 and 152 is set to at least DC is the intermediate voltage V in The combined resistance value of the first resistor 151 and the second resistor 152 as the low-voltage side resistance value when the voltage is lower than X, and the DC voltage V DC is the intermediate voltage V in It includes the resistance value of first resistor 151 as a high-voltage side resistance value greater than the low-voltage side resistance value when it is higher than X.

[0048] In particular, in the example of FIG. 2, the resistance change units 151 and 152 are connected to a DC voltage V DC is the intermediate voltage V in When the DC voltage V exceeds X, the total resistance value is switched between the low-voltage side resistance value (the combined resistance value of the first resistor 151 and the second resistor 152) and the high-voltage side resistance value (the resistance value of the first resistor 151). DC The total resistance value may be monotonically increased in any manner, either continuously or discretely, with respect to

[0049] 3 is a schematic graph of the current "LED IF" flowing through the indicator element 30 via the indicator control circuit 15 shown in FIG. 2. The horizontal axis represents the input voltage V between the high potential line and the low potential line. in (DC voltage V DC AC or DC voltage V DC In this example, the input voltage V in The rated voltage range or compatible voltage range of is the range with AC40 (or DC60) as the lower limit voltage and AC480 (approximately 480V in AC voltage) as the upper limit voltage. In the following example, the input voltage V in A case will be described where the voltage increases monotonically from the lower limit voltage "AC40" to the upper limit voltage "AC480".

[0050] Input voltage V in is the intermediate voltage V in When the lower limit voltage is "AC40" lower than X, no current flows through the Zener diode 154, and the transistor 156 in the photocoupler is in a conductive state. Therefore, the second resistor 152 is in a connected state, and the total resistance value of the resistance change parts 151, 152 is the combined resistance value (low-voltage side resistance value) of the first resistor 151 and the second resistor 152. The current flowing through the indicator element 30 in this case is the sum of the first current I1 flowing through the first resistor 151 and the second current I2 flowing through the second resistor 152.

[0051] As described above, the requirement for the indicator element 30 or the first resistor 151 and / or the second resistor 152 as the limiting resistor is that even if the inverter device 10 is operated at the lower limit voltage "AC40" of the rated voltage range, the residual charge corresponding to the lower limit voltage "AC40" must be at least a minimum current IF min To meet this requirement, the low-voltage side resistance (the combined resistance of the first resistor 151 and the second resistor 152) and / or the fixed resistor 153 must be able to pass a minimum current IF through the indicator element 30 when the lower limit voltage is "AC40". minIn the illustrated example, when the lower limit voltage is "AC40", the indicator element 30 flows a minimum current IF min Flush.

[0052] Input voltage V in The lower limit voltage "AC40" to the intermediate voltage V in X, the current (the sum of the first current I1 and the second current I2) flowing through the indicator element 30 also increases monotonically. However, as the input voltage V in The lower limit voltage is "AC40" and the intermediate voltage is V in In the range between X and 1, the current through the indicator element 30 is a predetermined maximum current IF max where the maximum current IF max is the maximum value of the current "LED IF" that is permitted to suppress the amount of heat generated per unit surface area or unit volume of the limiting resistors 151, 152, and 153 to a specified value or less. In this way, the low-voltage side resistance value (the combined resistance value of the first resistor 151 and the second resistor 152) and / or the fixed resistor 153 are set to the intermediate voltage V in Maximum current IF to indicator element 30 at time X max It is designed to draw the following current, "LED IF".

[0053] Input voltage V in is the intermediate voltage V in When the potential increases to X, a current flows through the Zener diode 154, and the transistor 156 in the photocoupler is switched to a non-conducting state. Therefore, the second resistor 152 is switched to a disconnected state, and the total resistance value of the resistance change units 151, 152 is the resistance value (high-voltage side resistance value) of the first resistor 151. The current flowing through the indicator element 30 in this case is the first current I1 flowing through the first resistor 151.

[0054] Thus, the current through the indicator element 30 varies with the input voltage V in is the intermediate voltage V in The sum of the first current I1 and the second current I2 before reaching X gives the input voltage V in is the intermediate voltage V in After reaching X, the first current I1 drops sharply. Even in this case, the intermediate voltage Vin The residual charge corresponding to X must be at least a minimum current IF min must be able to flow through the indicator element 30 or the first resistor 151. To meet this requirement, the high-voltage side resistance (first resistor 151) and / or the fixed resistor 153 must be able to withstand the intermediate voltage V in At time X, a minimum current IF flows through the indicator element 30 or the first resistor 151. min It is designed to flow a current of "LED IF" or more.

[0055] Input voltage V in is the intermediate voltage V in As the input voltage V increases from X to the upper limit voltage "AC480", the current (first current I1) flowing through the indicator element 30 also increases monotonically. in is the intermediate voltage V in In the range between X and the upper voltage limit "AC480", the current through the indicator element 30 is a maximum current IF max In this way, the high-voltage side resistance (first resistor 151) and / or the fixed resistor 153 is set to a value that allows a maximum current IF max It is designed to draw the following current, "LED IF".

[0056] As described above, according to the present embodiment, the current "LED IF" flowing through the indicator element 30 is a minimum current IF min and maximum current IF max Therefore, the residual charge in the smoothing capacitor 12 is at least equal to the minimum current IF min The first requirement is that the current flowing through the indicator element 30 must be within a maximum current IF max The second requirement, that the input current must be kept below 100 V, is met over a relatively wide range of operating voltages.

[0057] As shown by the dashed line in FIG. 3, the intermediate voltage V inWithout switching or changing the limiting resistor in the vicinity of X, the current “LED IF” through the indicator element 30 will in Maximum current IF in the voltage range above X max In this case, in order to suppress the amount of heat generated per unit surface area or unit volume of the limiting resistor to a specified amount or less, it is necessary to increase the surface area or volume of the limiting resistor, which leads to an increase in the size of the limiting resistor and, in turn, the inverter device 10. In contrast, according to the present embodiment, the input voltage V in Since the resistance values ​​of the resistance change sections 151 and 152 change in response to the change, it is not necessary to increase the size of the resistance change sections 151 and 152 in order to dissipate heat.

[0058] The present disclosure has been described above based on the embodiments. Various modifications are possible to the combinations of the components and processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included within the scope of the present disclosure.

[0059] In the above embodiments, the inverter device 10 is exemplified as a power control device, but the present disclosure is applicable to any power control device (e.g., a power supply device or a power conversion device) that controls or processes relatively large power (e.g., AC voltage of about 40 V or more), which is sometimes expressed as "high current."

[0060] In the above embodiment, one intermediate voltage V in Although an example in which the resistance value of the resistance change unit is switched once at X has been shown, a plurality of intermediate voltages may be provided between the lower limit voltage and the upper limit voltage, and the resistance value of the resistance change unit may be switched a plurality of times. in The resistance value may be continuously increased.

[0061] The configuration, action, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. For example, a processor, ROM, RAM, and various integrated circuits can be used as hardware resources. For example, programs such as an operating system and applications can be used as software resources. [Explanation of symbols]

[0062] 10 inverter device, 12 smoothing capacitor, 13 inverter, 14 voltage detection circuit, 15 indicator control circuit, 20 motor, 30 indicator element, 141 voltage dividing resistor, 151, 152 resistance change portion, 151 first resistor, 152 second resistor, 154 Zener diode, 155, 156 photocoupler.

Claims

1. an indicator element provided between a high potential line and a low potential line for providing power controlled by the power control device, the indicator element indicating a state of the power control device in response to a current flowing therethrough; a resistance change unit connected in series to the indicator element between the high potential line and the low potential line, the resistance change unit changing a resistance value according to a voltage between the high potential line and the low potential line; A power control device comprising:

2. 2. The power control device according to claim 1, wherein the resistance value of the resistance change section includes at least a low-voltage side resistance value when the voltage is lower than a predetermined intermediate voltage, and a high-voltage side resistance value that is greater than the low-voltage side resistance value when the voltage is higher than the intermediate voltage.

3. The power control device according to claim 2 , wherein the resistance change unit switches a resistance value between the low-voltage side resistance value and the high-voltage side resistance value when the voltage exceeds the intermediate voltage.

4. the resistance change section includes a first resistor and a second resistor connected in parallel to each other, A switching element is connected in series to the second resistor, the switching element being in a conductive state when the voltage is lower than the intermediate voltage and being in a non-conductive state when the voltage is higher than the intermediate voltage. The power control device according to claim 3 .

5. The power control device according to claim 4 , wherein the switching element is a photocoupler.

6. a switching signal generating unit that generates a switching signal for switching the switching element between the conductive state and the non-conductive state, the switching signal generating unit includes a limiting element that is provided between the high potential line and the low potential line and that does not allow a current required for generating the switching signal to flow when the voltage is lower than the intermediate voltage, and allows a current required for generating the switching signal to flow when the voltage is higher than the intermediate voltage. The power control device according to claim 4.

7. The power control device according to claim 6 , wherein the limiting element is constituted by a Zener diode.

8. a voltage detection circuit having a voltage dividing resistor connected between the high potential line and the low potential line, the voltage detection circuit detecting a voltage between the high potential line and the low potential line divided by the voltage dividing resistor; The limiting element is connected in series with at least a portion of the voltage dividing resistor. The power control device according to claim 6.

9. the low-voltage side resistance value allows a current equal to or greater than a minimum current at which the indicator element can operate to flow when the voltage is a predetermined lower limit voltage, and allows a current equal to or less than a predetermined maximum current to flow when the voltage is the intermediate voltage higher than the lower limit voltage; The high-voltage side resistance allows a current equal to or greater than the minimum current to flow when the voltage is the intermediate voltage, and allows a current equal to or less than the maximum current to flow when the voltage is a predetermined upper limit voltage higher than the intermediate voltage. The power control device according to any one of claims 2 to 8.

10. A power control device comprising: an indicator element provided between a high potential line and a low potential line which provide power controlled by the power control device, the indicator element indicating a state of the power control device in response to a current flowing therethrough; and a resistance change unit connected in series to the indicator element between the high potential line and the low potential line, A power control method that changes a resistance value in the resistance change portion according to a voltage between the high potential line and the low potential line.

11. A power control device comprising: an indicator element provided between a high potential line and a low potential line which provide power controlled by the power control device, the indicator element indicating a state of the power control device in response to a current flowing therethrough; and a resistance change unit connected in series to the indicator element between the high potential line and the low potential line, A storage medium storing a power control program that causes a computer to change the resistance value of the resistance change portion in accordance with the voltage between the high potential line and the low potential line.

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