Power conversion equipment and refrigeration cycle application equipment

Abstract

A power conversion device (1) for performing power conversion comprises: one or more switching elements included in at least one power converter among one or more power converters for performing power conversion; a waveform shape change unit capable of changing the waveform shapes of the switching waveforms of the switching elements; state quantity detection units (501 to 505) detecting state quantities indicating the operation states of the power conversion device (1); and a waveform shape control signal output unit (420) outputting a control signal used when the waveform shape change unit changes the switching waveforms of the switching elements in accordance with the state quantities.

Description

Power conversion devices, motor drive devices, and refrigeration cycle application equipment

[0001] The present disclosure relates to a power conversion device that performs power conversion, a motor drive device, and a refrigeration cycle application device.

[0002] Conventionally, the switching speed of a switching element has been changed by switching between gate resistors having different gate resistance values ​​and connecting them to the switching element. For example, Patent Document 1 discloses a technique for an inverter control device including an inverter main circuit having a plurality of switching elements, in which, when changing the gate drive waveform of the switching element, the gate resistor connected to the switching element is switched to a gate resistor having a different gate resistance value using a switch.

[0003] Japanese Patent Application Laid-Open No. 2012-200042

[0004] However, according to the above-mentioned conventional technology, a switch is used to select the gate resistor connected to the switching element, which means that in order to increase the number of types of gate drive waveforms, a large number of gate resistors and switches must be used, which increases the circuit size.

[0005] The present disclosure has been made in view of the above, and has an object to provide a power conversion device that is capable of changing the switching speed of switching elements while suppressing an increase in circuit size.

[0006] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a power conversion device that performs power conversion, including one or more switching elements included in at least one of one or more power converters that perform power conversion, a waveform shape modification unit that can modify the waveform shape of a switching waveform of the switching elements, a state quantity detection unit that detects a state quantity that indicates an operating state of the power conversion device, and a waveform shape control signal output unit that outputs a control signal when the waveform shape modification unit modifies the switching waveform of the switching elements in accordance with the state quantity.

[0007] The power conversion device according to the present disclosure has an advantage that it is possible to change the switching speed of the switching elements while suppressing an increase in circuit size.

[0008] FIG. 1 is a diagram showing a configuration example of a power conversion device according to embodiment 1. FIG. 2 is a diagram showing an example of turn-on joule loss, turn-on current, and turn-on voltage when the switching speed of the inverter switching element is slowed down in the power conversion device according to embodiment 1. FIG. 3 is a diagram showing an example of turn-on joule loss, turn-on current, and turn-on voltage when the switching speed of the inverter switching element is fastened in the power conversion device according to embodiment 1.and turn-on voltage. Figures showing an example of the relationship between noise and loss generated in a general switching element. First figure showing the effect obtained by changing the switching speed of the inverter switching element in the power conversion device according to embodiment 1. Second figure showing the effect obtained by changing the switching speed of the inverter switching element in the power conversion device according to embodiment 1. Figures showing an example of the configuration of the waveform shape modification unit of the power conversion device according to embodiment 1. First figure showing the relationship between the gate current output by the waveform shape modification unit and the gate voltage showing the rise speed of the switching element in the power conversion device according to embodiment 1. Second figure showing the relationship between the gate current output by the waveform shape modification unit and the gate voltage showing the rise speed of the switching element in the power conversion device according to embodiment 1. FIG. 3 is a diagram showing an example of the relationship between the basic pulse output by the basic pulse generating unit and the gate current output by the waveform shape changing unit in the power conversion device according to embodiment 1. FIG. 4 is a flowchart showing the operation of changing the waveform shape of the switching waveform of the switching element in the power conversion device according to embodiment 1. FIG. 5 is a diagram showing an example of the hardware configuration for realizing the control unit provided in the power conversion device according to embodiment 1. FIG. 6 is a diagram showing an example of the configuration of the power conversion device according to embodiment 2. FIG. 7 is a diagram showing an example of the configuration of the power conversion device according to embodiment 3. FIG. 8 is a diagram showing an example of the configuration of the power conversion device according to embodiment 4. FIG. 9 is a diagram showing an example of the configuration of the speed estimation device provided in the power conversion device according to embodiment 4. FIG. 10 is a diagram showing an example of the configuration of the power conversion device according to embodiment 1.FIG. 1 shows an example of each current and the capacitor voltage of the capacitor when the current flowing through the inverter is kept constant. FIG. 2 shows an example of each current and the capacitor voltage of the capacitor when the control unit of the power conversion device according to embodiment 5 controls the operation of the inverter to reduce the current flowing through the capacitor. FIG. 3 shows an example of the configuration of a power conversion device according to embodiment 6. FIG. 4 shows an example of the configuration of a refrigeration cycle application device according to embodiment 7.

[0009] Hereinafter, a power conversion device, a motor drive device, and a refrigeration cycle applied device according to embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] First Embodiment. FIG. 1 is a diagram illustrating an example of the configuration of a power conversion device 1 according to a first embodiment. The power conversion device 1 is connected to a commercial power supply 110 and a motor 314. The power conversion device 1 converts first AC power having a power supply voltage Vs supplied from the commercial power supply 110 into second AC power having a desired amplitude and phase, and supplies the second AC power to the motor 314. In the example of FIG. 1 , the commercial power supply 110 is a single-phase AC power supply, but it may also be a three-phase AC power supply. The power conversion device 1 includes a state quantity detection unit 501, a converter 130, a capacitor 210, a state quantity detection unit 502, an inverter 310, a state quantity detection unit 503, a state quantity detection unit 504, a state quantity detection unit 505, and a control unit 400. The power conversion device 1 and the motor 314 constitute a motor drive device 2.

[0011] The state quantity detection unit 501 detects a state quantity that indicates the operating state of the power conversion device 1. The state quantity detection unit 501 detects, for example, a voltage value of the AC power of the power supply voltage Vs supplied from the commercial power supply 110 to the converter 130, a current value of the AC power of the power supply voltage Vs supplied from the commercial power supply 110 to the converter 130, etc.

[0012] Converter 130 is a power converter that converts AC power of power supply voltage Vs supplied from commercial power supply 110 into DC power. Converter 130 includes rectifying elements 131 to 134, a reactor 135, a switching element 136, a freewheeling diode 137, a diode 138, and a drive circuit 150. Converter 130 has a bridge circuit formed by rectifying elements 131 to 134, rectifies first AC power of power supply voltage Vs supplied from commercial power supply 110, and boosts and outputs the rectified DC power. Drive circuit 150 generates a drive signal for actually driving switching element 136, based on a basic pulse generated by a basic pulse generating unit 410 of control unit 400 (described later). The switching element 136 may be, for example, an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOSFET), a bipolar transistor, or the like, but is not limited to these. The configuration of the converter 130 is not limited to the example shown in FIG. 1 . In the converter 130, one or more of the rectifying elements 131 to 134 may be configured with a switching element. In the power conversion device 1 of the first embodiment shown in FIG. 1 , the converter 130 may have only a rectifying function and may not have a boosting function. In addition, when the commercial power supply 110 is a three-phase AC power supply, the converter 130 is configured to include six rectifying elements.

[0013] Capacitor 210 is connected to the output terminal of converter 130 and smoothes the DC power converted by converter 130. Capacitor 210 is, for example, an electrolytic capacitor or a film capacitor.

[0014] The state quantity detection unit 502 detects a state quantity that indicates the operating state of the power conversion device 1. The state quantity detection unit 502 detects, for example, the voltage value of the DC power supplied from the capacitor 210 to the inverter 310.

[0015] The inverter 310 is a power converter connected to both ends of the capacitor 210. The inverter 310 includes switching elements 311a to 311f and freewheeling diodes 312a to 312f. The inverter 310 turns on and off the switching elements 311a to 311f under the control of the control unit 400, converts the power output from the converter 130 and the capacitor 210 into second AC power having a desired amplitude and phase, i.e., generates second AC power, and outputs it to the motor 314. The switching elements 311a to 311f are, for example, IGBTs, MOSFETs, bipolar transistors, etc., but are not limited to these. The circuit configuration of the inverter 310 is not particularly limited, and may be a full-bridge circuit, a single-phase bridge circuit, a half-bridge circuit, or the like. In addition, in this embodiment, the inverter 310 includes a waveform shape changing unit 340 that can change the waveform shape of the switching waveforms of the switching elements 311a to 311f. The waveform shape modification unit 340 is capable of outputting two or more waveform shapes as the waveform shapes of the switching waveforms of the switching elements 311a to 311f. In the example of FIG. 1, the waveform shape modification unit 340 is configured to be able to modify the waveform shapes of the switching waveforms of the switching elements 311a to 311f, but it is also possible to modify the waveform shape of the switching waveform of at least one of the switching elements 311a to 311f. Furthermore, the inverter 310 may be configured to include a waveform shape modification unit 340 for each of the switching elements 311a to 311f. The detailed operation of the waveform shape modification unit 340 will be described later.

[0016] The state quantity detection unit 503 detects a state quantity indicating the operating state of the power conversion device 1. The state quantity detection unit 503 detects, for example, a voltage value of the second AC power supplied from the inverter 310 to the motor 314 which is a load, a current value of the second AC power supplied from the inverter 310 to the motor 314 which is a load, etc. The state quantity detection unit 504 detects a state quantity indicating the operating state of the power conversion device 1. The state quantity detection unit 504 detects, for example, a current value of the DC power supplied from the capacitor 210 to the inverter 310, etc. The state quantity detection unit 505 detects a state quantity indicating the operating state of the power conversion device 1. The state quantity detection unit 505 detects, for example, a current flowing through the switching elements 311b, 311d, 311f, etc.

[0017] The control unit 400 acquires the state quantities detected by the state quantity detection units 501 to 505 from the state quantity detection units 501 to 505, and controls the operations of the converter 130 and the inverter 310 based on the acquired state quantities, specifically, controls the on / off of the switching element 136 of the converter 130, and controls the on / off of the switching elements 311a to 311f of the inverter 310. The control unit 400 includes a basic pulse generation unit 410 and a waveform shape control signal output unit 420.

[0018] The basic pulse generation unit 410 has a duty ratio corresponding to the state quantities detected by the state quantity detection units 501 to 505 and generates a basic pulse for controlling the operation of the switching element 136 of the converter 130. The basic pulse generation unit 410 also has a duty ratio corresponding to the state quantities detected by the state quantity detection units 501 to 505 and generates a basic pulse for controlling the operation of the switching elements 311a to 311f of the inverter 310. The basic pulse is, for example, a PWM (Pulse Width Modulation) signal having a duty ratio corresponding to the state quantities detected by the state quantity detection units 501 to 505. The basic pulse generation unit 410 outputs a basic pulse for controlling the operation of the switching element 136 of the converter 130 to the converter 130 and outputs a basic pulse for controlling the operation of the switching elements 311a to 311f of the inverter 310 to the waveform shape control signal output unit 420.

[0019] The waveform shape control signal output unit 420 sets the waveform shapes of the switching waveforms of the switching elements 311a to 311f when the waveform shape modification unit 340 of the inverter 310 changes the switching waveforms of the switching elements 311a to 311f, in accordance with the state quantities detected by the state quantity detection units 501 to 505, and outputs a control signal indicating the set waveform shape. Specifically, when the switching elements 311a to 311f are turned on and off based on the basic pulses for controlling the operation of the switching elements 311a to 311f of the inverter 310 generated by the basic pulse generation unit 410, the waveform shape control signal output unit 420 controls the magnitude of the drive signals that the waveform shape modification unit 340 of the inverter 310 outputs to the switching elements 311a to 311f to actually drive the switching elements 311a to 311f, and the timing at which the drive signals are output. The waveform shape control signal output unit 420 outputs a control signal for controlling the operation of the waveform shape modification unit 340 to the waveform shape modification unit 340. When the inverter 310 has a waveform shape modification unit 340 for each of the switching elements 311a to 311f, i.e., six waveform shape modification units 340, the control unit 400 may be configured to have a waveform shape control signal output unit 420 for each waveform shape modification unit 340, i.e., six waveform shape control signal output units 420.

[0020] In the example of FIG. 1 , the control unit 400 acquires state quantities detected by the state quantity detection units 501 to 505 from the state quantity detection units 501 to 505 and controls the operation of the converter 130 and the inverter 310 based on the acquired state quantities. However, this is not limited to this. The control unit 400 can control the operation of the converter 130 and the inverter 310 based on state quantities acquired from at least one of the state quantity detection units 501 to 505. In the power conversion device 1, the state quantity detection units 501 to 505 detect, as state quantities, voltages or currents input to each component of the power conversion device 1 and voltages or currents output from each component of the power conversion device 1 in the above example, but the detection targets are not limited to these. Furthermore, the installation locations of the state quantity detection units 501 to 505 are not limited to the example of FIG. 1 . The power conversion device 1 does not need to have all of the state quantity detection units 501 to 505 arranged as shown in FIG. 1 . The power conversion device 1 may include state quantity detection units anywhere other than those shown in the figure as long as the state quantities can be detected. The power conversion device 1 may be provided with a state quantity detection unit at a position where it can detect state quantities such as noise generated by the power conversion device 1, the motor 314, etc., losses generated by the power conversion device 1, the motor 314, etc., and the temperature of each component of the power conversion device 1, the motor 314, etc.

[0021] Furthermore, since the basic pulse generating section 410 and the waveform shape control signal output section 420 both operate based on the state quantities acquired from the state quantity detecting sections 501 to 505, the control section 400 may combine the functions of the basic pulse generating section 410 and the waveform shape control signal output section 420 into a single configuration.

[0022] The motor 314 is a load connected to the power conversion device 1. The motor 314 is, for example, a compressor motor for driving a compressor. The motor 314 rotates in accordance with the amplitude and phase of the second AC power supplied from the inverter 310 to perform compression. For example, when the compressor is a hermetic compressor, the load torque of the motor 314 driving the compressor can often be considered a constant torque load. The motor 314 may have a Y-connection, a Δ-connection, or a specification that allows switching between the Y-connection and the Δ-connection, with respect to the motor windings (not shown). Furthermore, the load connected to the power conversion device 1, i.e., the inverter 310, is not limited to the motor 314 for driving the compressor and may be a fan motor or the like. Furthermore, the load connected to the power conversion device 1 is not limited to the motor 314 and may be a load other than the motor 314.

[0023] In this embodiment, the power conversion device 1 can change the waveform shapes of the switching waveforms of the switching elements 311a to 311f of the inverter 310 by the waveform shape control signal output unit 420 and the waveform shape modification unit 340. Specifically, the power conversion device 1 can change the switching speed, delay time, etc. of the switching elements 311a to 311f of the inverter 310.

[0024] FIG. 2 is a diagram showing examples of turn-on joule loss, turn-on current, and turn-on voltage when the switching speed of the switching elements 311a to 311f of the inverter 310 in the power conversion device 1 according to the first embodiment is slowed. FIG. 3 is a diagram showing examples of turn-on joule loss, turn-on current, and turn-on voltage when the switching speed of the switching elements 311a to 311f of the inverter 310 in the power conversion device 1 according to the first embodiment is fastened. In FIGS. 2 and 3, A represents turn-on joule loss, B represents turn-on current, and C represents turn-on voltage. In FIGS. 2 and 3, the horizontal axis represents time. For example, the turn-on current is the current flowing through the switching element 311a, the turn-on voltage is the voltage across the switching element 311a, and the turn-on joule loss is the product of the turn-on current and the turn-on voltage. However, the measurement target is not limited to the switching element 311a, and may be the other switching elements 311b to 311f. 2 and 3 show differences in the characteristics of the switching elements 311a to 311f of the inverter 310 depending on the switching speed, and the specific values ​​of "slow" and "fast" switching speeds are not particularly important. As shown in FIGS. 2 and 3, slowing the switching speed reduces noise represented by the peak value of the turn-on current of B, but increases loss represented by the area of ​​the turn-on joule loss of A. Also, as shown in FIGS. 2 and 3, increasing the switching speed increases noise represented by the peak value of the turn-on current of B, but decreases loss represented by the area of ​​the turn-on joule loss of A. In other words, there is a trade-off between the noise and loss generated by the switching elements 311a to 311f.

[0025] In the power conversion device 1, the waveform shape modification unit 340 is configured by a digital gate driver. Alternatively, in the power conversion device 1, the switching elements 311a to 311f of the inverter 310 and the waveform shape modification unit 340 are configured by a digital gate driver module. This allows the power conversion device 1 to change the switching speed of the switching elements 311a to 311f of the inverter 310 by changing a command value in software without changing the hardware, and to control the noise and loss generated in the switching elements 311a to 311f to a desired state.

[0026] Fig. 4 is a diagram showing an example of the relationship between noise and loss generated in a typical switching element. As mentioned above, there is a trade-off between noise and loss generated in a switching element. Therefore, as shown in Fig. 4, in a typical switching element, increasing the switching speed increases noise but reduces loss, and decreasing the switching speed reduces noise but increases loss.

[0027] FIG. 5 is a first diagram illustrating the effect obtained by changing the switching speed of the switching elements 311a to 311f of the inverter 310 in the power conversion device 1 according to the first embodiment. Even if the power conversion device 1 is operating within the noise range specified for the product in which the power conversion device 1 is installed, when the load state of the motor 314 changes from a light load to a heavy load, the curve showing the characteristics of the noise and loss generated by the switching elements 311a to 311f shifts to the upper right as shown in FIG. 5, resulting in an increase in noise. In other words, in the power conversion device 1, the heavier the load, the greater the noise. Therefore, the power conversion device 1 can reduce the noise generated by the switching elements 311a to 311f by slowing down the switching speed of the switching elements 311a to 311f. Similarly, even if the power conversion device 1 is operating within the loss range specified for the product in which the power conversion device 1 is installed, when the load state of the motor 314 changes from a light load to a heavy load, the curve showing the characteristics of the noise and loss generated by the switching elements 311a to 311f shifts to the upper right as shown in Figure 5, resulting in an increase in loss. In other words, in the power conversion device 1, the heavier the load, the greater the loss. Therefore, the power conversion device 1 can reduce the loss generated by the switching elements 311a to 311f by increasing the switching speed of the switching elements 311a to 311f.

[0028] When the load state of the motor 314 changes from a light load to a heavy load, the waveform shape control signal output unit 420 changes the waveform shapes of the switching waveforms of the switching elements 311a to 311f so as to reduce losses generated in the switching elements 311a to 311f while ensuring that the noise generated in the switching elements 311a to 311f satisfies specified requirements. Alternatively, when the load state of the motor 314 changes from a light load to a heavy load, the waveform shape control signal output unit 420 changes the waveform shapes of the switching waveforms of the switching elements 311a to 311f so as to reduce noise generated in the switching elements 311a to 311f while ensuring that the losses generated in the switching elements 311a to 311f satisfy specified requirements.

[0029] 6 is a second diagram illustrating the effect obtained by changing the switching speed of the switching elements 311a to 311f of the inverter 310 in the power conversion device 1 according to the first embodiment. The power conversion device 1, specifically the waveform shape modification unit 340, divides, for example, the turn-on period or the turn-off period of a single switching operation of the switching elements 311a to 311f into two or more periods, and modifies the amplitude of the gate current or gate voltage for the switching elements 311a to 311f to different magnitudes in each of the divided periods. By optimizing the switching waveforms of the switching elements 311a to 311f as shown in FIG. 6, the power conversion device 1 can obtain noise and loss characteristics that are generated by the switching elements 311a to 311f, which are not obtainable with typical switching elements such as those shown in FIG. 4.

[0030] The configuration of the waveform shape modification unit 340 will now be described. For ease of explanation, a case will be described in which the waveform shape modification unit 340 is capable of modifying the waveform shape of the switching waveform of one switching element 311a. FIG. 7 is a diagram showing an example of the configuration of the waveform shape modification unit 340 of the power conversion device 1 according to the first embodiment. FIG. 7 also shows an example of the configuration of one digital gate driver module configured by the waveform shape modification unit 340 and the switching element 311a. As shown in FIG. 1, the waveform shape modification unit 340 is included in the inverter 310, which is a power converter including the switching element 311a. The waveform shape changing unit 340 includes n P-channel MOSFETs (PMOSs) for turn-on, n PreDrivers for operating the n PMOSs, n N-channel MOSFETs (NMOSs) for turn-off, and n PreDrivers for operating the n NMOSs.

[0031] The waveform shape changing unit 340 is connected to a control power supply Vdd and a ground GND. The waveform shape changing unit 340 changes the number of PMOS or NMOS transistors to be operated based on a control signal from the waveform shape control signal output unit 420, thereby changing the gate current I, which is a drive signal to be output to the switching element 311a, during each of the turn-on period and the turn-off period. Ｇ The waveform shape changing unit 340 can change the amplitude value of the gate current I output to the switching element 311a in n ways, thereby adjusting the switching speed of the switching element 311a. Ｇ The absolute value of can be increased, and the switching speed of the switching element 311a can be increased. In addition, the waveform shape changing unit 340 can adjust the switching speed of the switching element 311a more precisely as the number of PMOS and NMOS included therein increases, and the gate current I Ｇ The faster the response of the increase or decrease of the gate current I Ｇ It is possible to adjust the number of PMOS or NMOS transistors operated by the waveform shape modification unit 340. The control signal from the waveform shape control signal output unit 420 may be an analog signal or a digital signal as long as it can change the number of PMOS or NMOS transistors operated by the waveform shape modification unit 340. In addition, the example of FIG. 7 shows that there are m parallel control signals from the waveform shape control signal output unit 420 to the waveform shape modification unit 340, but this is just an example, and the number of control signals is not limited to m. The number of control signals may be any number that can indicate whether each PMOS transistor and each NMOS transistor is operable or not, or it may be one signal as long as it is an analog signal that indicates a voltage or the like.

[0032] FIG. 8 shows the gate current I output by the waveform shape modification unit 340 in the power conversion device 1 according to the first embodiment. Ｇ and the gate voltage V, which indicates the rise speed of the switching element 311a. Ｇ 9 is a first diagram showing the relationship between the gate current I output by the waveform shape modification unit 340 in the power conversion device 1 according to the first embodiment. Ｇ and the gate voltage V, which indicates the rise speed of the switching element 311a. Ｇ8 and 9, the waveform shape changing unit 340 changes the gate current I Ｇ The larger the gate voltage V Ｇ 8 and 9, the waveform shape changing unit 340 can increase the rise time of the output gate current I Ｇ The smaller the gate voltage V Ｇ 5, the power conversion device 1 can output a gate current I when it is desired to reduce noise generated by the switching element 311a. Ｇ When it is desired to reduce the loss occurring in the switching element 311a by decreasing the switching speed, the output gate current I Ｇ The switching speed can be increased by increasing the gate current I Ｇ and gate voltage V Ｇ The waveform of the gate current I is an ideal example, and in reality, as shown in FIGS. Ｇ It takes time for the current to reach a constant value.

[0033] FIG. 10 shows the gate current I output by the waveform shape modification unit 340 in the power conversion device 1 according to the first embodiment. Ｇ and the gate voltage V, which indicates the rise speed of the switching element 311a. Ｇ 10, the waveform shape changing unit 340 divides the turn-on period and changes the gate current I Ｇ That is, the waveform shape changing section 340 can change the magnitude of the gate current I Ｇ This allows the power conversion device 1 to finely adjust the magnitude of the gate current I Ｇ 6, it is possible to perform control so as to reduce the loss generated in the switching element 311a while reducing the noise generated in the switching element 311a.

[0034] 8 to 10 have been used to explain the turn-on period of the switching element 311a as an example, but the same applies to the turn-off period of the switching element 311a. Fig. 11 shows the basic pulse output by the basic pulse generating unit 410 and the gate current I output by the waveform shape changing unit 340 in the power conversion device 1 according to the first embodiment. Ｇ 11 is a diagram illustrating an example of the relationship between |Ig2| and |Ig1|. In FIG. 11, |Ig2|>|Ig1|. The waveform shape changing unit 340 changes the gate current I Ｇ The period during which the current Ig2 having the larger amplitude is output is divided, and the gate current I Ｇ Then, the gate current I of the current Ig1 with the next smallest amplitude is output. Ｇ Alternatively, the gate current I of the current Ig1 with the small amplitude may be output first. Ｇ After outputting the gate current I of the current Ig2 with the next largest amplitude, Ｇ Similarly, the waveform shape changing unit 340 may output the gate current I Ｇ The period during which the current with the largest amplitude -Ig2 is output is divided, and the gate current I Ｇ Then, the gate current I of the next smallest amplitude current -Ig1 is output. Ｇ Alternatively, the gate current I of the current −Ig1 with a small amplitude may be output first. Ｇ After outputting the next largest current, the gate current Ig2 Ｇ may be output.

[0035] In this way, the waveform shape changing unit 340 divides at least one of the turn-on period and the turn-off period of the switching element 311a into two or more periods based on the control signal output from the waveform shape control signal output unit 420, and controls the gate current I for the switching element 311a in each divided period. ＧThe waveform shape changing section 340 includes a plurality of transistors, and by changing the number of transistors to be operated based on the control signal output from the waveform shape control signal output section 420, the amplitude of the gate current I Ｇ The amplitude of can be changed.

[0036] Furthermore, the waveform shape changing unit 340 changes the gate current I Ｇ The waveform shape changer 340 can change the switching waveform to a different waveform shape for each switching period of the switching element 311a during operation of the power conversion device 1. In this case, the waveform shape control signal output unit 420 can change the waveform shape of the switching waveform of the switching element 311a at the same period as the switching period of the switching element 311a. The waveform shape control signal output unit 420 may also change the waveform shape of the switching waveform of the switching element 311a at a period that is a positive integer multiple of the switching period of the switching element 311a.

[0037] 7 is merely an example and is not intended to be limiting. In this manner, the waveform shape modification unit 340 can more precisely adjust the switching speed of the switching element 311a by digital control using a plurality of MOS (Metal Oxide Semiconductors), compared to analog control that physically switches gate resistors as described in Patent Document 1. Furthermore, the waveform shape modification unit 340 may use transistors other than MOS transistors for its internal transistors.

[0038] In the above example, the waveform shape changing unit 340 changes the number of PMOS or NMOS to be operated in accordance with the acquired control signal, and generates a gate current I Ｇ to the switching element 311a, but is not limited to this. The waveform shape changing unit 340 changes the gate current I ＧThe output pattern, i.e., waveform shape, of the gate current I is stored in advance, and the output pattern, i.e., waveform shape, corresponding to the acquired control signal is output. Ｇ Furthermore, the waveform shape changing unit 340 may output a previously acquired control signal and a gate current I Ｇ The output pattern, i.e., waveform shape, of the gate current I is stored in memory, and when the same control signal is acquired, the stored output pattern, i.e., waveform shape is used. Ｇ The waveform shape changing section 340 may output the gate current I Ｇ By storing the output pattern, i.e., waveform shape, of the gate current I Ｇ This reduces the processing load when outputting.

[0039] In the example of FIG. 7, the waveform shape changing unit 340 changes the gate current I Ｇ The waveform shape changing unit 340 adjusts the switching speed of the switching element 311a by changing the gate voltage V Ｇ and the gate voltage V Ｇ By changing the value of the switching speed of the switching element 311a, the switching speed of the switching element 311a can be adjusted and the waveform shape of the switching waveform of the switching element 311a can be changed.

[0040] In this way, the waveform shape changing unit 340 divides at least one of the turn-on period and the turn-off period of the switching element 311a into two or more periods based on the control signal output from the waveform shape control signal output unit 420, and changes the gate voltage V Ｇ The waveform shape changing section 340 includes a plurality of transistors, and by changing the number of transistors to be operated based on the control signal output from the waveform shape control signal output section 420, the amplitude of the gate voltage V Ｇ The amplitude of can be changed.

[0041] 12 is a flowchart showing an operation of changing the waveform shapes of the switching waveforms of the switching elements 311a to 311f in the power conversion device 1 according to the first embodiment. In the power conversion device 1, the basic pulse generation unit 410 generates basic pulses for driving the switching elements 311a to 311f of the inverter 310 based on the state quantities acquired from the state quantity detection units 501 to 505 (step S1). As described above, in the control unit 400, the basic pulse generation unit 410 generates basic pulses based on the state quantities acquired from the state quantity detection units 501 to 505, and determines the timings for turning on and off the switching elements 311a to 311f. The basic pulse generation unit 410 outputs the generated basic pulses to the waveform shape control signal output unit 420.

[0042] The waveform shape control signal output unit 420 sets a waveform shape for changing the waveform shape of the switching waveform of the switching elements 311a to 311f of the inverter 310, based on the basic pulse obtained from the basic pulse generation unit 410 and the state quantities obtained from the state quantity detection units 501 to 505. As described above, in the control unit 400, the waveform shape control signal output unit 420 sets the waveform shapes of the switching waveforms at the timings for turning on and off the switching elements 311a to 311f determined by the basic pulse generation unit 410, based on the state quantities obtained from the state quantity detection units 501 to 505. The waveform shape control signal output unit 420 outputs a control signal to the waveform shape modification unit 340, which can change the magnitude and output timing of the drive signal in accordance with the set waveform shape (step S2).

[0043] The waveform shape changing unit 340 changes the gate current I Ｇ The waveform shape of the gate current I after the waveform shape change is performed is changed based on the control signal obtained from the waveform shape control signal output unit 420 (step S3). Ｇare output to the switching elements 311 a to 311 f of the inverter 310 .

[0044] Next, a description will be given of the hardware configuration of the control unit 400 included in the power conversion device 1. Fig. 13 is a diagram showing an example of a hardware configuration that realizes the control unit 400 included in the power conversion device 1 according to embodiment 1. The control unit 400 is realized by a processor 91 and a memory 92.

[0045] The processor 91 is a CPU (Central Processing Unit, also called a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). Examples of memory 92 include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory). Memory 92 is not limited to these, and may also be a magnetic disk, optical disk, compact disk, minidisc, or DVD (Digital Versatile Disc).

[0046] As described above, according to this embodiment, in the power conversion device 1, the waveform shape control signal output unit 420 of the control unit 400 outputs a control signal for changing the switching waveforms of the switching elements 311a to 311f in the waveform shape change unit 340 of the inverter 310, in accordance with the state quantities detected by the state quantity detection units 501 to 505. The waveform shape change unit 340 of the inverter 310 changes the gate current I to be output to the switching elements 311a to 311f based on the control signal output from the waveform shape control signal output unit 420. Ｇ or gate voltage V ＧBy changing the gate current I to be output to the switching elements 311a to 311f in one switching period, the waveform shapes of the switching waveforms of the switching elements 311a to 311f are changed. This allows the power conversion device 1 to change the switching speed of the switching elements 311a to 311f while suppressing an increase in the circuit size. Ｇ or gate voltage V Ｇ By finely adjusting the waveforms, it is possible to realize the waveform shapes of the switching waveforms of the switching elements 311a to 311f that could not be realized by the method of Patent Document 1 and the like.

[0047] Embodiment 2 In the first embodiment, a case has been described in which the waveform shapes of the switching waveforms of the switching elements 311a to 311f of the inverter 310 are changed in the power conversion device 1. In the second embodiment, a case will be described in which the waveform shape of the switching waveform of the switching element 136 of the converter 130 is changed in the power conversion device 1.

[0048] 14 is a diagram showing an example of the configuration of a power conversion device 1 according to the second embodiment. The power conversion device 1 is connected to a commercial power supply 110 and a motor 314. The power conversion device 1 converts first AC power of a power supply voltage Vs supplied from the commercial power supply 110 into second AC power having a desired amplitude and phase, and supplies the second AC power to the motor 314. The power conversion device 1 includes a state quantity detection unit 501, a converter 130, a capacitor 210, a state quantity detection unit 502, an inverter 310, a state quantity detection unit 503, a state quantity detection unit 504, a state quantity detection unit 505, and a control unit 400. The power conversion device 1 and the motor 314 constitute a motor drive device 2.

[0049] The power conversion device 1 of the second embodiment shown in FIG. 14 is configured by removing the waveform shape modification unit 340 from the inverter 310 and adding a drive circuit 350, and removing the drive circuit 150 from the converter 130 and adding a waveform shape modification unit 140. The power conversion device 1 of the second embodiment shown in FIG. 14 also differs from the power conversion device 1 of the first embodiment shown in FIG. 1 in that the output destinations of the basic pulse generation unit 410 and the waveform shape control signal output unit 420 are changed. Specifically, the basic pulse generation unit 410 outputs a basic pulse for controlling the operation of the switching element 136 of the converter 130 to the waveform shape control signal output unit 420, and outputs a basic pulse for controlling the operation of the switching elements 311a to 311f of the inverter 310 to the inverter 310. The waveform shape control signal output unit 420 also outputs a control signal for controlling the operation of the waveform shape modification unit 140 to the waveform shape modification unit 140.

[0050] In the inverter 310, the drive circuit 350 generates drive signals for actually driving the switching elements 311a to 311f based on the basic pulses generated by the basic pulse generating section 410 of the control section 400.

[0051] In this embodiment, the waveform shape control signal output unit 420 sets the waveform shape of the switching waveform of the switching element 136 when the waveform shape modification unit 140 of the converter 130 changes the switching waveform of the switching element 136, in accordance with the state quantities detected by the state quantity detection units 501 to 505, and outputs a control signal indicating the set waveform shape. Specifically, when the switching element 136 is turned on and off based on the basic pulse for controlling the operation of the switching element 136 of the converter 130 generated by the basic pulse generation unit 410, the waveform shape control signal output unit 420 controls the magnitude of the drive signal that the waveform shape modification unit 140 of the converter 130 outputs to the switching element 136 to actually drive the switching element 136, and the timing at which the drive signal is output. The waveform shape control signal output unit 420 outputs a control signal for controlling the operation of the waveform shape modification unit 140 to the waveform shape modification unit 140.

[0052] The waveform shape modification unit 140 is capable of modifying the waveform shape of the switching waveform of the switching element 136. The waveform shape modification unit 140 is capable of outputting two or more waveform shapes as the waveform shape of the switching waveform of the switching element 136. As shown in FIG. 14 , the waveform shape modification unit 140 is included in a converter 130, which is a power converter including the switching element 136. The configuration of the waveform shape modification unit 140 is similar to the configuration of the waveform shape modification unit 340 of the first embodiment shown in FIG. 7 . That is, the waveform shape modification unit 140 and the switching element 136 are configured by one digital gate driver module. Similarly to the waveform shape modification unit 340, the waveform shape modification unit 140 also outputs the gate current I to the switching element 136 as a drive signal. Ｇ Instead, the gate voltage V output to the switching element 136 Ｇ may be adjusted.

[0053] In this way, the waveform shape changing unit 140 divides at least one of the turn-on period and the turn-off period of the switching element 136 into two or more periods based on the control signal output from the waveform shape control signal output unit 420, and controls the gate current I to the switching element 136 in each divided period. Ｇ or gate voltage V Ｇ The waveform shape changing section 140 includes a plurality of transistors, and by changing the number of transistors to be operated based on the control signal output from the waveform shape control signal output section 420, the amplitude of the gate current I Ｇ or gate voltage V Ｇ As a result, the power conversion device 1 performs the same operation as in the first embodiment, and thereby the waveform shape control signal output unit 420 and the waveform shape modification unit 140 can modify the waveform shape of the switching waveform of the switching element 136 of the converter 130.

[0054] As described above, according to this embodiment, in the power conversion device 1, the waveform shape control signal output unit 420 of the control unit 400 outputs a control signal for changing the switching waveform of the switching element 136 in the waveform shape change unit 140 of the converter 130, in accordance with the state quantities detected by the state quantity detection units 501 to 505. The waveform shape change unit 140 of the converter 130 determines the gate current I to be output to the switching element 136 based on the control signal output from the waveform shape control signal output unit 420. Ｇ or gate voltage V Ｇ The waveform shape change unit 140 can change the waveform shape of the switching waveform of the switching element 136 in the same way that the waveform shape change unit 340 of the first embodiment changes the waveform shape of the switching waveform of the switching element 311a. This allows the power conversion device 1 to change the switching speed of the switching element 136 while suppressing an increase in circuit size. The power conversion device 1 changes the gate current I Ｇ or gate voltage V Ｇ By finely adjusting the value, it is possible to realize a waveform shape of the switching waveform of the switching element 136 that could not be realized by the method of Patent Document 1 and the like.

[0055] In this embodiment, the configuration of the converter 130 for which the waveform shape of the switching elements is changed is not limited to the example shown in FIG. 14 . FIG. 15 is a first diagram illustrating a rectification portion of the converter 130 included in the power conversion device 1 according to embodiment 2. FIG. 16 is a second diagram illustrating the rectification portion of the converter 130 included in the power conversion device 1 according to embodiment 2. FIG. 17 is a third diagram illustrating the rectification portion of the converter 130 included in the power conversion device 1 according to embodiment 2. FIGS. 15 to 17 only illustrate differences from FIG. 14 , and omit the illustration of the waveform shape change unit 140. As shown in FIG. 15 , in a configuration in which the converter 130 includes a reactor 135, switching elements 136a to 136d, and freewheel diodes 137a to 137d, the waveform shape change unit 140 may change the waveform shapes of the switching waveforms of the switching elements 136a to 136d. 16, in a configuration in which converter 130 includes reactor 135, rectifying elements 131 to 134, switching element 136, freewheel diode 137, and rectifying elements 131a to 134a, waveform shape modification unit 140 may change the waveform shape of the switching waveform of switching element 136. In a configuration in which the connected commercial power source is commercial power source 110a, which is a three-phase AC power source, and converter 130 includes reactors 135a to 135c, rectifying elements 131a to 131c, switching elements 136a to 136c, and freewheel diodes 137a to 137c, waveform shape modification unit 140 may change the waveform shape of the switching waveform of switching elements 136a to 136c.

[0056] Embodiment 3. In the first embodiment, a case has been described in which the waveform shapes of the switching waveforms of the switching elements 311a to 311f of the inverter 310 are changed in the power conversion device 1. In the second embodiment, a case has been described in which the waveform shape of the switching waveform of the switching element 136 of the converter 130 is changed in the power conversion device 1. In the third embodiment, a case will be described in which the waveform shapes of the switching waveforms of the switching elements 311a to 311f of the inverter 310 are changed, and the waveform shape of the switching waveform of the switching element 136 of the converter 130 is changed.

[0057] 18 is a diagram showing an example of the configuration of a power conversion device 1 according to the third embodiment. The power conversion device 1 is connected to a commercial power supply 110 and a motor 314. The power conversion device 1 converts first AC power of a power supply voltage Vs supplied from the commercial power supply 110 into second AC power having a desired amplitude and phase, and supplies the second AC power to the motor 314. The power conversion device 1 includes a state quantity detection unit 501, a converter 130, a capacitor 210, a state quantity detection unit 502, an inverter 310, a state quantity detection unit 503, a state quantity detection unit 504, a state quantity detection unit 505, and a control unit 400. The power conversion device 1 and the motor 314 constitute a motor drive device 2.

[0058] The power conversion device 1 of the third embodiment shown in FIG. 18 is configured by removing the drive circuit 150 from the converter 130 and adding a waveform shape modification unit 140 to the power conversion device 1 of the first embodiment shown in FIG. 1 . Furthermore, the power conversion device 1 of the third embodiment shown in FIG. 18 has output destinations of the basic pulse generation unit 410 and the waveform shape control signal output unit 420 changed from those of the power conversion device 1 of the first embodiment shown in FIG. 1 . Specifically, the basic pulse generation unit 410 outputs a basic pulse for controlling the operation of the switching elements 311a to 311f of the inverter 310 to the waveform shape control signal output unit 420, and outputs a basic pulse for controlling the operation of the switching element 136 of the converter 130 to the waveform shape control signal output unit 420. Furthermore, the waveform shape control signal output unit 420 outputs a control signal for controlling the operation of the waveform shape modification unit 340 to the waveform shape modification unit 340, and outputs a control signal for controlling the operation of the waveform shape modification unit 140 to the waveform shape modification unit 140.

[0059] In the present embodiment, the waveform shape control signal output unit 420 performs the operation described in the first embodiment as well as the operation described in the second embodiment. Furthermore, in the present embodiment, the waveform shape modification unit 340 performs the same operation as that described in the first embodiment, and the waveform shape modification unit 140 performs the same operation as that described in the second embodiment. As a result, by performing the same operation as in the first embodiment, the power conversion device 1 can change the waveform shape of the switching waveform of the switching elements 311a to 311f of the inverter 310 by the waveform shape control signal output unit 420 and the waveform shape modification unit 340. Furthermore, by performing the same operation as in the second embodiment, the power conversion device 1 can change the waveform shape of the switching waveform of the switching element 136 of the converter 130 by the waveform shape control signal output unit 420 and the waveform shape modification unit 140.

[0060] In this embodiment, the power conversion device 1 can also perform control such that at a certain timing, one of the waveform shape modification units 140, 340 changes the waveform shape of the switching waveform of the switching element, while the other does not change the waveform shape of the switching waveform of the switching element. In this embodiment, the switching elements whose switching waveforms are changed by the waveform shape modification units 140, 340 of the power conversion device 1 are one or more switching elements included in at least one of the one or more power converters that perform power conversion in the power conversion device 1.

[0061] As described above, according to this embodiment, in the power conversion device 1, the waveform shape control signal output unit 420 of the control unit 400 outputs a control signal when the waveform shape change unit 340 of the inverter 310 changes the switching waveforms of the switching elements 311a to 311f, in accordance with the state quantities detected by the state quantity detection units 501 to 505, and outputs a control signal when the waveform shape change unit 140 of the converter 130 changes the switching waveform of the switching element 136. The waveform shape change unit 340 of the inverter 310 controls the gate current I to be output to the switching elements 311a to 311f based on the control signal output from the waveform shape control signal output unit 420. Ｇ or gate voltage V Ｇ The waveform shape changing unit 140 of the converter 130 changes the waveform shape of the switching waveform of the switching elements 311a to 311f based on the control signal output from the waveform shape control signal output unit 420. Ｇ or gate voltage V Ｇ By changing the gate current I , the waveform shape of the switching waveform of the switching element 136 is changed. This allows the power conversion device 1 to change the switching speed of the switching elements 311a to 311f and the switching element 136 while suppressing an increase in circuit size. The power conversion device 1 changes the gate current I , which is output to the switching elements 311a to 311f and the switching element 136 in one switching period. Ｇ or gate voltage V ＧBy finely adjusting the waveforms, it is possible to realize the waveform shapes of the switching waveforms of the switching elements 311a to 311f and the switching element 136, which could not be realized by the method of Patent Document 1 and the like.

[0062] Fourth Embodiment A case will be described in which an adaptive observer is applied to the power conversion device 1 of the first to third embodiments as sensorless control of the motor 314. Specifically, the power conversion device 1 of the first embodiment will be described as an example.

[0063] Fig. 19 is a diagram showing a configuration example of a power conversion device 1 according to embodiment 4. The power conversion device 1 according to embodiment 4 shown in Fig. 19 is obtained by adding a speed estimation device 101 to the power conversion device 1 according to embodiment 1 shown in Fig. 1. Fig. 20 is a diagram showing a configuration example of the speed estimation device 101 provided in the power conversion device 1 according to embodiment 4. The speed estimation device 101 estimates the rotation speed of the motor 314 by using a voltage vector and a current vector applied to the motor 314 using an adaptive observer technique, and calculates an estimated angular speed ω^ ｒ Output as

[0064] The speed estimation device 101 estimates the voltage vector, the current vector, and the estimated angular speed ω^ ｒ a model deviation calculation unit 11 that calculates a model deviation ε based on the model deviation ε, and a first estimated angular velocity ω^ that is a low-frequency component including a DC component of the actual angular velocity based on the model deviation ε. ｒ１ The velocity estimation device 101 also includes a first angular velocity estimator 21 that calculates a second estimated angular velocity ω^ as a high-frequency component of the actual angular velocity based on a specific high-frequency component included in the model deviation ε. ｒ２ and a second angular velocity estimator 22 that calculates the first estimated angular velocity ω^ ｒ１ The second estimated angular velocity ω^ ｒ２ By adding ｒ The velocity estimation device 101 is characterized in that it includes a second angular velocity estimation unit 22. The velocity estimation device 101 calculates the first estimated angular velocity ω^ ｒ１ and the second estimated angular velocity ω^ ｒ２ The sum of these values ​​is the estimated angular velocity ω^ ｒ The calculated value is fed back to the model deviation calculation unit 11 as a function of time.

[0065] The model deviation calculation unit 11 calculates the voltage vector, current vector, and estimated angular velocity ω^ of the motor 314. ｒ The model deviation calculator 14 includes a current estimator 12 that calculates and outputs an estimated magnetic flux vector and an estimated current vector based on the above, a subtractor 13 that subtracts the current vector from the estimated current vector to calculate and output a current deviation vector, and a deviation calculator 14 that receives the current deviation vector as an input, extracts the orthogonal component of the estimated magnetic flux vector as a scalar quantity, and outputs this value as a model deviation ε. Known methods for extracting the orthogonal component of the estimated magnetic flux vector as a scalar quantity include a method of coordinate transforming the current deviation vector onto two axes of rotation and a method of calculating the magnitude of the cross product of the current deviation vector and the estimated magnetic flux vector.

[0066] The current estimator 12 estimates the current and magnetic flux from the state equation of the motor 314. Here, it is assumed that the motor 314 is a general interior permanent magnet synchronous AC motor, but the current estimator 12 can estimate the current in a similar manner even if the motor 314 is other than an interior permanent magnet synchronous AC motor, as long as the state equation can be formulated. Examples of the motor 314 other than an interior permanent magnet synchronous AC motor include a surface permanent magnet synchronous motor and an induction motor. Furthermore, although a rotary motor is described in this embodiment, the same technology can also be applied to a linear motor. The reason for this is that a linear motor can be interpreted as a rotary motor with an infinite rotor radius.

[0067] In this way, the power conversion device 1 can apply an adaptive observer to the sensorless control of the motor 314 .

[0068] Embodiment 5. A case will be described in which control is performed in the power conversion devices 1 of embodiments 1 to 3, which can suppress deterioration of the smoothing capacitor 210 while suppressing an increase in the size of the device. Specifically, the power conversion device 1 of embodiment 1 will be described as an example.

[0069] Fig. 21 is a diagram showing a configuration example of a power conversion device 1 according to embodiment 5. The configuration of the power conversion device 1 of embodiment 5 shown in Fig. 21 is the same as the configuration of the power conversion device 1 of embodiment 1 shown in Fig. 1. The converter 130 is a rectifier unit that has a bridge circuit formed by rectifying elements 131 to 134 and rectifies and outputs the first AC power of the power supply voltage Vs supplied from the commercial power supply 110.

[0070] In this embodiment, the control unit 400 controls the operation of the inverter 310 so that the inverter 310 outputs, to the motor 314, which is a load, second AC power including pulsation corresponding to the pulsation of the power flowing from the converter 130, which is a rectifier, to the capacitor 210. The pulsation corresponding to the pulsation of the power flowing into the capacitor 210 is, for example, pulsation that varies depending on the frequency of the pulsation of the power flowing into the capacitor 210. In this way, the control unit 400 suppresses the current flowing through the capacitor 210. Note that the control unit 400 does not need to use all of the detection values ​​acquired from each detection unit, and may perform control using only some of the detection values.

[0071] The operation of the control unit 400 included in the power conversion device 1 will be described. In this embodiment, in the power conversion device 1, the load generated by the inverter 310 and the motor 314 can be considered to be a constant load, and the following description will be given assuming that a constant current load is connected to the capacitor 210 when viewed in terms of the current output from the capacitor 210. Here, as shown in FIG. 21 , the current flowing from the converter 130 is referred to as current I1, the current flowing to the inverter 310 is referred to as current I2, and the current flowing from the capacitor 210 is referred to as current I3. Current I2 is the sum of current I1 and current I3. Current I3 can be expressed as the difference between current I2 and current I1, i.e., current I2 - current I1. The discharge direction of capacitor 210 is considered to be the positive direction of current I3, and the charge direction of capacitor 210 is considered to be the negative direction. That is, current may flow into or out of capacitor 210.

[0072] FIG. 22 shows an example of the currents I1 to I3 and the capacitor voltage Vdc of the capacitor 210 when the current output from the converter 130 is smoothed by the capacitor 210 and the current I2 flowing through the inverter 310 is kept constant, as a comparative example. From top to bottom, the diagram shows the currents I1, I2, I3, and the capacitor voltage Vdc of the capacitor 210 generated in response to the current I3. The vertical axes of the currents I1, I2, and I3 represent the current values, while the vertical axis of the capacitor voltage Vdc represents the voltage value. The horizontal axes all represent time t. Note that, although a carrier component of the inverter 310 is actually superimposed on the currents I2 and I3, it is omitted here. The same applies hereinafter. As shown in FIG. 22 , in the power conversion device 1, if the current I1 flowing from the converter 130 is sufficiently smoothed by the capacitor 210, the current I2 flowing through the inverter 310 will be a constant current value. However, a large current I3 flows through the capacitor 210, which can cause degradation. Therefore, in the present embodiment, in the power conversion device 1, the control unit 400 controls the current I2 flowing through the inverter 310, that is, controls the operation of the inverter 310, so as to reduce the current I3 flowing through the capacitor 210.

[0073] FIG. 23 is a diagram illustrating an example of the currents I1 to I3 and the capacitor voltage Vdc of the capacitor 210 when the control unit 400 of the power conversion device 1 according to the fifth embodiment controls the operation of the inverter 310 to reduce the current I3 flowing through the capacitor 210. From top to bottom, the diagram illustrates the currents I1, I2, I3, and the capacitor voltage Vdc of the capacitor 210 generated in response to the current I3. The vertical axes of the currents I1, I2, and I3 represent current values, and the vertical axis of the capacitor voltage Vdc represents voltage values. The horizontal axes all represent time t. By controlling the operation of the inverter 310 so that the current I2 shown in FIG. 23 flows through the inverter 310, the control unit 400 of the power conversion device 1 can reduce the frequency components of the current flowing from the converter 130 to the capacitor 210 and reduce the current I3 flowing through the capacitor 210, compared to the example of FIG. 22 . Specifically, the control unit 400 controls the operation of the inverter 310 so that the current I2 including the pulsating current whose main component is the frequency component of the current I1 flows through the inverter 310 .

[0074] In this way, in the power conversion device 1, the control unit 400 controls the operation of the inverter 310, which is a power converter, so that pulsation corresponding to the state quantities detected by the state quantity detection units 501, 502, and 503 is superimposed on the drive pattern of the motor 314 connected to the inverter 310, thereby suppressing the charge / discharge current of the capacitor 210. This allows the power conversion device 1 to suppress deterioration of the smoothing capacitor 210.

[0075] Sixth Embodiment A case will be described in which, in the power conversion devices 1 of the first to third embodiments, control is performed that can suppress fluctuations in DC voltage even when the number of switching times of the short-circuiting part that shorts the commercial power supply 110, which is an AC power supply, is changed in response to load conditions. Specifically, the power conversion device 1 of the first embodiment will be described as an example.

[0076] FIG. 24 is a diagram illustrating a configuration example of a power conversion device 1 according to a sixth embodiment. The power conversion device 1 according to the sixth embodiment illustrated in FIG. 24 is configured by removing the converter 130 and the capacitor 210 from the power conversion device 1 according to the first embodiment illustrated in FIG. 1 and adding a reactor 135, a rectifying unit 170, and a short-circuiting unit 30. The rectifying unit 170 includes a rectifying circuit configured with four rectifying elements 131 to 134, and a capacitor 210 connected between output terminals of the rectifying circuit to smooth the voltage of a full-wave rectified waveform output from the rectifying circuit. The rectifying unit 170 rectifies the first AC power supplied from the commercial power source 110 and outputs the rectified power.

[0077] The short-circuiting unit 30 short-circuits the commercial power supply 110 via the reactor 135. The short-circuiting unit 30 is composed of a diode bridge 31 connected in parallel to the commercial power supply 110 via the reactor 135, and a short-circuiting element 32 connected to both output terminals of the diode bridge 31. When the short-circuiting element 32 is a metal oxide semiconductor field effect transistor, the gate of the short-circuiting element 32 is connected to the control unit 400, and the short-circuiting element 32 is turned on and off by a drive signal from the control unit 400. When the short-circuiting element 32 is turned on, the commercial power supply 110 is short-circuited via the reactor 135 and the diode bridge 31.

[0078] The control unit 400 controls the short-circuiting operation of the short-circuiting unit 30. The control unit 400 controls the on / off of the short-circuiting element 32 by current open-loop control in the short-circuiting operation mode so as to short-circuit the short-circuiting unit 30 at least twice during a half cycle of the power supply. The control unit 400 shorts the short-circuiting unit 30 at least twice during a half cycle of the commercial power supply 110 based on the load conditions. This allows the power conversion device 1 to suppress fluctuations in DC voltage even when the number of switching operations of the short-circuiting unit 30 that short-circuits the commercial power supply 110 is changed in response to the load conditions.

[0079] Seventh Embodiment Fig. 25 is a diagram showing a configuration example of a refrigeration cycle-applied apparatus 900 according to a seventh embodiment. The refrigeration cycle-applied apparatus 900 according to the seventh embodiment includes the power conversion device 1 described in the first embodiment. The refrigeration cycle-applied apparatus 900 according to the seventh embodiment can also include the power conversion device 1 described in any of the second to sixth embodiments. The refrigeration cycle-applied apparatus 900 according to the seventh embodiment can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters. In Fig. 25, components having the same functions as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment.

[0080] The refrigeration cycle application equipment 900 includes a compressor 315 incorporating the motor 314 in embodiment 1, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910, which are attached via refrigerant piping 912.

[0081] Inside the compressor 315, a compression mechanism 904 that compresses the refrigerant and a motor 314 that operates the compression mechanism 904 are provided.

[0082] The refrigeration cycle device 900 can perform heating or cooling operation by switching the four-way valve 902. The compression mechanism 904 is driven by a motor 314 that is variably controlled in speed.

[0083] During heating operation, as shown by the solid arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, passes through the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, the outdoor heat exchanger 910 and the four-way valve 902 and returns to the compression mechanism 904.

[0084] During cooling operation, as shown by the dashed arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, and returns to the compression mechanism 904 through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906 and the four-way valve 902.

[0085] During heating operation, the indoor heat exchanger 906 acts as a condenser to release heat, and the outdoor heat exchanger 910 acts as an evaporator to absorb heat. During cooling operation, the outdoor heat exchanger 910 acts as a condenser to release heat, and the indoor heat exchanger 906 acts as an evaporator to absorb heat. The expansion valve 908 reduces the pressure of the refrigerant to expand it.

[0086] Even if the refrigeration cycle device 900 is operating within the specified noise range, when the load state of the motor 314 changes from a light load to a heavy load, the curve showing the characteristics of the noise and losses generated by the switching elements 311a to 311f, etc., shifts upward to the upper right as shown in FIG. 5 , resulting in an increase in noise. Therefore, the refrigeration cycle device 900 can reduce the noise generated by the switching elements 311a to 311f, etc., by slowing the switching speed of the switching elements 311a to 311f, etc. Similarly, even if the refrigeration cycle device 900 is operating within the specified loss range, when the load state of the motor 314 changes from a light load to a heavy load, the curve showing the characteristics of the noise and losses generated by the switching elements 311a to 311f, etc., shifts upward to the upper right as shown in FIG. 5 , resulting in an increase in losses. Therefore, the refrigeration cycle device 900 can reduce the losses generated by the switching elements 311a to 311f, etc., by increasing the switching speed of the switching elements 311a to 311f, etc.

[0087] In the power conversion device 1 included in the refrigeration cycle device 900, the digital gate driver module, which is composed of the waveform shape changing unit 340 and switching elements 311a to 311f included in the inverter 310, generates a large surge voltage and a lot of electromagnetic noise when the switching speed is fast. When the refrigeration cycle device 900 uses a flammable refrigerant, there is a possibility that the refrigerant may leak and burn due to discharge caused by electromagnetic noise. Therefore, the refrigeration cycle device 900 sets the switching speed of the digital gate driver module included in the power conversion device 1 according to the flammability of the refrigerant used in the refrigeration cycle device 900. For example, the refrigeration cycle device 900 slows the switching speed of the digital gate driver module included in the power conversion device 1 the more flammable the refrigerant used in the refrigeration cycle device 900 is. By slowing the switching speed of the digital gate driver module, the refrigeration cycle device 900 can reduce surge voltage and suppress discharge caused by electromagnetic noise, thereby preventing refrigerant from burning even if it leaks from the refrigeration cycle device 900.

[0088] Refrigerants used in the refrigeration cycle equipment 900 include, for example, R1234yf, R1234ze(E), R1243zf, HFO1123, HFO1132(E), R1132a, CF3I, R290, R463A, R466A, R454A, R454B, and R454C.

[0089] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0090] 1 Power conversion device, 2 Motor drive device, 11 Model deviation calculation unit, 12 Current estimator, 13 Subtractor, 14 Deviation calculation unit, 21 First angular velocity estimation unit, 22 Second angular velocity estimation unit, 23 Adder, 30 Short circuit unit, 31 Diode bridge, 32 Short circuit element, 101 Speed ​​estimation device, 110, 110a Commercial power supply, 130 Converter, 131 to 134, 131a to 134a, 131b, 131c Rectifying element, 135, 135a to 135c Reactor, 136, 136a to 136d, 311a to 311f Switching element, 137, 137a to 137d, 312a to 312f Freewheel diode, 138 Diode, 140, 340 Waveform shape change unit, 150, 350 Drive circuit, 170 rectifier, 210 capacitor, 310 inverter, 314 motor, 315 compressor, 400 control unit, 410 basic pulse generation unit, 420 waveform shape control signal output unit, 501 to 505 state quantity detection unit, 900 refrigeration cycle applicable equipment, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 expansion valve, 910 outdoor heat exchanger, 912 refrigerant piping.

Claims

1. A power conversion device that performs power conversion, One or more switching elements included in at least one of the one or more power converters that perform power conversion; a waveform shape changing unit capable of changing a waveform shape of a switching waveform of the switching element without physically switching a gate resistor; A state quantity detection unit that detects a state quantity indicating an operating state of the power conversion device; a waveform shape control signal output unit that outputs a control signal when the waveform shape changing unit changes the switching waveform of the switching element in response to the state quantity; A power conversion device comprising:

2. A power conversion device for performing power conversion, One or more switching elements included in at least one of the one or more power converters that perform power conversion; a plurality of transistors mounted to drive the switching elements; a waveform shape changing unit capable of changing a waveform shape of a switching waveform of the switching element by changing the number of the plurality of transistors to be operated; A state quantity detection unit that detects a state quantity indicating an operation state of the power conversion device; a waveform shape control signal output unit that outputs a control signal when the waveform shape changing unit changes the switching waveform of the switching element in response to the state quantity; A power conversion device comprising:

3. the waveform shape changing unit is capable of dividing at least one of a turn-on period and a turn-off period of the switching element into two or more periods based on the control signal output from the waveform shape control signal output unit, and changing the amplitude of a gate current or a gate voltage for the switching element to a different magnitude in each divided period, for the waveform shape of the switching waveform of the switching element. The power conversion device according to claim 1 or 2.

4. the waveform shape changing unit includes a plurality of transistors, and changes the number of the transistors to be operated based on the control signal output from the waveform shape control signal output unit, thereby changing the amplitude of the gate current or the gate voltage. The power conversion device according to claim 3 .

5. The waveform shape changing unit is capable of changing the switching waveform to a different waveform shape for each switching period of the switching element during operation of the power conversion device. The power conversion device according to claim 1 or 2.

6. the waveform shape control signal output unit changes the waveform shape of the switching waveform of the switching element at a period equal to a switching period of the switching element or a period that is a positive integer multiple of the switching period of the switching element. The power conversion device according to claim 1 or 2.

7. a speed estimation device comprising: a model deviation calculation unit which calculates a model deviation based on a voltage, a current, and an estimated angular velocity of an AC motor; a first angular velocity estimation unit which calculates a first estimated angular velocity as a low-frequency component including a DC component of an actual angular velocity based on the model deviation; a second angular velocity estimation unit which calculates a second estimated angular velocity as a high-frequency component of the actual angular velocity based on a specific high-frequency component included in the model deviation; and an adder which adds up the first estimated angular velocity and the second estimated angular velocity, and which feeds back a sum of the first estimated angular velocity and the second estimated angular velocity to the model deviation calculation unit as the estimated angular velocity; The power conversion device according to claim 1 or 2, comprising:

8. A rectification unit that rectifies AC power supplied from a commercial power source; A capacitor connected to an output terminal of the rectifier unit; a control unit including the waveform shape control signal output unit, controlling an operation of the inverter such that a pulsation corresponding to the state quantity detected by the state quantity detection unit is superimposed from the inverter serving as the power converter on a drive pattern of a motor connected to the inverter, thereby suppressing a charge / discharge current of the capacitor; The power conversion device according to claim 1 or 2, comprising:

9. A rectification unit that rectifies AC power supplied from a commercial power source; a short circuit unit that short-circuits the commercial power supply via a reactor; a control unit including the waveform shape control signal output unit and controlling a short-circuiting operation of the short-circuiting unit; Equipped with the control unit shorts the short-circuiting unit at least two times during a half cycle of the commercial power supply based on a load condition. The power conversion device according to claim 1 or 2.

10. A power conversion device comprising the power conversion device according to claim 1 or 2, The refrigerant used is any one of R1234yf, R1234ze(E), R1243zf, HFO1123, HFO1132(E), R1132a, CF3I, R290, R463A, R466A, R454A, R454B, and R454C; setting a switching speed of a digital gate driver module included in the power conversion device according to the flammability of the refrigerant; Refrigeration cycle application equipment.