Power conversion device for resonant circuit and ac power control method for resonant circuit

Abstract

To provide a power conversion device for a resonant circuit and an AC power control method for a resonant circuit that can improve the stability of a resonant state of AC power in a resonant circuit when controlling the AC power output to the resonant circuit.SOLUTION: A power conversion device 100 includes a power conversion section 10 that outputs AC power to an output target including a resonant circuit 20, and a control section 50. The control section 50 includes a detection signal generation section 60 and an output control section 70. The detection signal generation section 60 outputs multiple physical quantities calculated from a detection value Ia at the output target as a detection signal IF. The output control section 70 generates a control signal C1 for controlling both the amplitude and phase of the voltage or current in the AC power output to the resonant circuit 20, on the basis of the detection signal IF and an output command IR.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power conversion device for a resonant circuit and a method for controlling AC power for a resonant circuit. [Background technology]

[0002] BACKGROUND ART Conventionally, a power conversion device for a resonant circuit is known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 describes a power conversion device that supplies AC power to an electric resistance welded pipe load via a resonant circuit. This resonant circuit is composed of an inductive impedance and a capacitor connected in parallel to the electric resistance welded pipe load. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-341286 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, when AC power to a resonant circuit is controlled as in the power conversion device described in Patent Document 1, if a load fluctuation such as a fluctuation in impedance occurs in the resonant circuit, the resonant state of the AC power in the resonant circuit may become unstable. Therefore, when AC power to the resonant circuit is controlled, it is desired to improve the stability of the resonant state of the AC power in the resonant circuit.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a power conversion device for a resonant circuit and an AC power control method for a resonant circuit that can improve the stability of the resonant state of AC power in the resonant circuit when controlling AC power output to the resonant circuit. [Means for solving the problem]

[0007] In order to achieve the above object, a power conversion device for a resonant circuit according to a first aspect of the present invention includes a power conversion unit that outputs AC power to an output object including a resonant circuit, and a control unit that controls the AC power output from the power conversion unit, wherein the control unit includes a detection signal generation unit configured to output, as detection signals, multiple physical quantities calculated from detection values ​​of at least one of the current and voltage in the output object including the resonant circuit, and an output control unit configured to generate, based on the detection signal and an output command corresponding to the multiple physical quantities of the detection signal, a control signal for controlling both the amplitude and phase of the voltage or current in the AC power output to the resonant circuit.

[0008] As described above, a power conversion device for a resonant circuit according to a first aspect of the present invention generates a control signal for controlling both the amplitude and phase of the voltage or current of AC power output to the resonant circuit based on a detection signal calculated as multiple physical quantities and an output command corresponding to the multiple physical quantities of the detection signal. This allows the control signal to control both the amplitude and phase of the voltage or current of the AC power, thereby improving control responsiveness to load fluctuations when load fluctuations, such as impedance fluctuations in the output target, occur. Therefore, unlike when control responsiveness is low, control instability can be suppressed even when load fluctuations occur. As a result, when controlling the AC power output to the resonant circuit, the stability of the resonant state of the AC power in the resonant circuit can be improved.

[0009] In the power conversion device for a resonant circuit according to the first aspect, the output control unit preferably includes a vibration suppression unit configured to output, based on the detection signal and the output command, a suppression signal for suppressing vibrations in at least one of a current and a voltage in an output object corresponding to the detection value, and a tracking control unit configured to output a tracking signal for causing at least one of a current and a voltage in the output object corresponding to the detection value to follow the output command, and is configured to generate a control signal based on the suppression signal output by the vibration suppression unit and the tracking signal output by the tracking control unit. With this configuration, the output control unit includes the vibration suppression unit that outputs the suppression signal for suppressing vibrations and the tracking control unit that outputs the tracking signal for causing the AC power to follow the output command, so that the control signal from the output control unit can suppress vibrations in the output object and control the AC power to follow the output command. Therefore, the AC power can be output more stably in accordance with the output command, thereby further improving the stability of the resonant state of the AC power in the resonant circuit.

[0010] In this case, the tracking control unit is preferably configured to output the tracking signal based on a detection signal and an output command different from those of the vibration suppression unit. With this configuration, the vibration suppression unit and the tracking control unit can separately control the physical quantities of the voltage and current in the AC power output to the resonant circuit. Therefore, the control of the AC power output to the resonant circuit can be more stable than when the vibration suppression unit and the tracking control unit use a common detection signal.

[0011] In the power converter for a resonant circuit, the output control section has a vibration suppression section and a tracking control section, and the vibration suppression section is preferably configured to output the suppression signal by performing feedback control including at least proportional control. With this configuration, the vibration suppression section can suppress the vibration component in the detection signal by proportional control, thereby making it possible to more stably control the output AC output.

[0012] In the power conversion device for a resonant circuit, the output control unit has a vibration suppression unit and a tracking control unit, and the tracking control unit is preferably configured to output the tracking signal by performing feedback control including at least integral control. With this configuration, the tracking control unit performs integral control to suppress steady-state deviation with respect to the output command, allowing the detection signal to track the output command, thereby making it possible to more stably control the AC power output to the resonant circuit.

[0013] In the power conversion device for a resonant circuit, the output control unit preferably includes a characteristic input unit configured to output a preset correction signal corresponding to the characteristic of the output object, and is configured to generate a control signal based on the suppression signal and the tracking signal corrected by the correction signal from the characteristic input unit. With this configuration, the preset correction signal corresponding to changes in at least one of the current and voltage corresponding to the detected value of the output object can be used to correct the tracking signal to respond to changes in the detected value without feedback control. This allows at least one of the current and voltage corresponding to the detected value of the output object to follow the output command with better responsiveness, thereby further improving the stability of the resonant state of AC power in the resonant circuit.

[0014] In the power conversion device for a resonant circuit, in which the output control section has a vibration suppression section and a tracking control section, the output control section preferably has a startup control section configured to output a set startup tracking signal separately from the tracking signal when the power conversion section is started up, and is configured to output a control signal generated based on the startup tracking signal from the startup control section at start-up, and then output a control signal generated based on the detection signal and the output command. With this configuration, control at start-up of the power conversion section is executed based on the startup tracking signal output separately from the tracking signal, so that stable control can be executed even when the detected value of the output target is not stable at start-up.

[0015] In the power conversion device for a resonant circuit, the output control unit has a vibration suppression unit and a tracking control unit, and the detection signal generation unit is preferably configured to extract predetermined frequency components from the detection values ​​as the plurality of physical quantities and output the extracted predetermined frequency components as the detection signal. With this configuration, even when the detection values ​​to be output contain multiple frequency components, a control signal can be generated using the detection signal from which the predetermined frequency components have been extracted so as to make the AC power more stable. As a result, the stability of the resonant state of the AC power in the resonant circuit can be further improved.

[0016] In this case, the detection signal generation unit is preferably configured to extract a detection signal having a predetermined frequency component that is a frequency component of the voltage or current of the AC power output from the power conversion unit. With this configuration, a control signal for controlling the AC power can be generated using the detection signal from which the frequency component of the voltage or current of the AC power output from the power conversion unit is extracted, thereby making it possible to output the AC power more stably. As a result, the stability of the resonant state of the AC power in the resonant circuit can be further improved.

[0017] In the power converter for a resonant circuit in which the detection signal generating unit outputs a detection signal from which a predetermined frequency component has been extracted, the detection signal generating unit is preferably configured to output a detection signal from which the predetermined frequency component has been extracted and a detection signal from which an exclusion frequency component, which is a component of a frequency to be excluded that is different from the predetermined frequency component, is extracted. The tracking control unit is configured to output a tracking signal based on the detection signal from which the predetermined frequency component has been extracted and an output command corresponding to the predetermined frequency component, and the vibration suppression unit is configured to output a suppression signal based on the detection signal from which the exclusion frequency component has been extracted and an output command corresponding to the exclusion frequency component. This configuration allows the predetermined frequency component and the exclusion frequency component, which is a component of a frequency to be excluded that is different from the predetermined frequency component, to be separately controlled. Therefore, even if vibration of the exclusion frequency component occurs in the output target due to load fluctuations or the like, the exclusion frequency component can be effectively suppressed. As a result, the stability of the resonant state of AC power in the resonant circuit can be further improved.

[0018] In the power converter for a resonant circuit in which a detection signal having a predetermined frequency component corresponding to the frequency component of the voltage or current of AC power is extracted, the detection signal generator is preferably configured to perform a rotational coordinate transformation on the detection value using a reference phase of the voltage or current of the AC power output from the power converter, thereby extracting the predetermined frequency component from the detection value and converting it into two physical quantities, a d-axis component and a q-axis component, and output the detection signal. With this configuration, the rotational coordinate transformation can be easily performed to convert the detection value into the two physical quantities, the d-axis component and the q-axis component, extracted as the frequency components of the voltage or current of the AC power. Therefore, a control signal for further stabilizing the AC power can be easily generated, thereby easily improving the stability of the resonant state of the AC power in the resonant circuit.

[0019] In this case, the detection signal generator is preferably configured to correct the reference phase based on a delay correction amount corresponding to a delay of the detection value relative to the reference phase, and to output the detection signal by performing a rotational coordinate transformation using the reference phase corrected by the delay correction amount. Here, if a delay occurs in the detection process or the control process, a phase shift occurs in the phase of the acquired detection value relative to the phase of at least one of the actual current and voltage in the output target. In such a case, the phase shift is thought to reduce the accuracy of extraction of the specified frequency component and the stability of the control process. In consideration of this, the present invention corrects the reference phase based on a delay correction amount corresponding to a delay of the detection value relative to the reference phase. This makes it possible to prevent a decrease in the accuracy of extraction of the specified frequency component even when a phase shift occurs in the detection value, thereby preventing a decrease in the stability of the control.

[0020] In the power converter for a resonant circuit in which the detection signal generating unit outputs a detection signal from which a predetermined frequency component has been extracted, the detection signal generating unit is preferably configured to output the detection signal from which the predetermined frequency component has been extracted by converting the detection value into two physical quantities: an amplitude component indicating the amplitude of the detection value and a phase difference component indicating the phase difference of the detection value relative to a reference phase of the predetermined frequency. With this configuration, by converting into the two physical quantities, the amplitude component and the phase difference component, it is possible to directly detect both the amplitude and phase of the detection value. Therefore, a tracking signal can be generated from the detection signal in which both the amplitude and phase have been directly detected, and the amplitude and phase of the AC power can be more accurately controlled by a control signal generated based on the tracking signal, thereby further improving the stability of the resonant state of the AC power in the resonant circuit.

[0021] In the power conversion device for a resonant circuit in which the tracking control unit outputs a tracking signal based on a detection signal different from that of the vibration suppression unit and an output command, the detection signal generation unit is preferably configured to output a detection signal including a preliminary detection signal indicating one physical quantity including at least one of the effective value, average value, and peak value of the detection value, and the tracking control unit is configured to output the tracking signal based on the preliminary detection signal different from the detection signal of the vibration suppression unit and a preliminary output command that is an output command corresponding to the preliminary detection signal. With this configuration, even when the tracking signal for tracking the output command is output based on the preliminary detection signal indicating one physical quantity including at least one of the effective value, average value, and peak value of the detection value, the detection signal converted into a plurality of physical quantities can be used to generate the tracking signal and the suppression signal for controlling both the amplitude and phase of the voltage or current of the AC power, thereby stabilizing the control of the AC power output to the resonant circuit. Therefore, even when at least one of the current and voltage in the output target corresponding to the detected value is made to follow the output command using one physical quantity including at least one of the effective value, average value, and peak value of the detected value, the stability of the resonant state of the AC power in the resonant circuit can be improved.

[0022] An AC power control method for a resonant circuit according to a second aspect of the present invention includes the steps of: outputting, as detection signals, a plurality of physical quantities calculated from detected values ​​of at least one of a current and a voltage in an output object including the resonant circuit from which AC power is output; and generating, based on the detection signal including the plurality of physical quantities and an output command corresponding to the plurality of physical quantities of the detection signal, a control signal for controlling both the amplitude and phase of the voltage or current in the AC power output to the resonant circuit.

[0023] According to a second aspect of the present invention, an AC power control method for a resonant circuit generates a control signal for controlling both the amplitude and phase of the voltage or current of AC power output to the resonant circuit based on a detection signal calculated as multiple physical quantities and an output command corresponding to the multiple physical quantities of the detection signal. This allows the control signal to control both the amplitude and phase of the voltage or current of the AC power, thereby improving control responsiveness to load fluctuations when load fluctuations, such as impedance fluctuations in the output target, occur. Therefore, unlike when control responsiveness is low, control instability can be suppressed even when load fluctuations occur. As a result, a method for controlling AC power for a resonant circuit can be provided that, when controlling the AC power output to the resonant circuit, can improve the stability of the resonant state of AC power in the resonant circuit. [Effects of the Invention]

[0024] According to the present invention, as described above, when controlling AC power output to a resonant circuit, it is possible to improve the stability of the resonant state of AC power in the resonant circuit. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a circuit diagram showing a configuration of a power conversion device according to a first embodiment. [Figure 2] 1 is a block diagram showing a configuration of a power conversion device according to a first embodiment. [Figure 3] FIG. 10 is a diagram showing an example of detected values ​​in an output target. [Figure 4] 10A and 10B are diagrams for explaining rotational coordinate transformation in a detection signal generating unit. [Figure 5] 10A and 10B are diagrams for explaining suppression of vibration in a detection signal and follow-up to an output command. [Figure 6] FIG. 3 is a flowchart illustrating a control process of an AC power control method for a resonant circuit by the power conversion device according to the first embodiment. [Figure 7]FIG. 10 is a block diagram showing the configuration of a power conversion device according to a second embodiment. [Figure 8] FIG. 10 is a block diagram showing the configuration of a power conversion device according to a third embodiment. [Figure 9] FIG. 10 is a block diagram showing the configuration of a power conversion device according to a fourth embodiment. [Figure 10] FIG. 10 is a diagram for explaining rotational coordinate transformation according to the fourth embodiment. [Figure 11] FIG. 10 is a block diagram showing the configuration of a power conversion device according to a fifth embodiment. [Figure 12] FIG. 10 is a block diagram showing the configuration of a power conversion device according to a sixth embodiment. [Figure 13] FIG. 4 is a diagram showing an example of a power conversion device according to a modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0027] [First embodiment] The configuration of a power conversion device 100 according to a first embodiment of the present invention will be described with reference to FIGS.

[0028] (Configuration of power conversion device) As shown in FIG. 1, a power conversion device 100 converts AC power from a commercial power source 101 and outputs the converted power. The power conversion device 100 is, for example, an induction heating device that heats a heated portion 102a of a load 102 using a heating coil 22. As an example, the power conversion device 100 constitutes an electric resistance welded pipe welding device. The power conversion device 100 includes a power conversion unit 10, a resonant circuit 20, a detection unit 30, a drive unit 40, and a control unit 50. The power conversion device 100 is an example of a "power conversion device for a resonant circuit" in the claims. The resonant circuit 20 is an example of an "output target" in the claims.

[0029] The power conversion unit 10 includes a rectifier circuit 11, a smoothing capacitor 12, and an inverter unit 13. The power conversion unit 10 outputs AC power to a resonant circuit 20, which is an output target. In the first embodiment, the voltage of the AC power output from the power conversion unit 10 is controlled by a control unit 50. The power conversion unit 10 converts AC power input from a commercial power source 101, and outputs the converted AC power to a load 102.

[0030] The rectifier circuit 11 rectifies AC power from a commercial power source 101 and converts it into DC power. The rectifier circuit 11 includes, for example, four full-bridge connected diodes. The smoothing capacitor 12 smoothes the DC power rectified by the rectifier circuit 11. The inverter unit 13 converts the DC power converted by the rectifier circuit 11 into AC power and outputs the converted AC power to the load 102. The inverter unit 13 includes four full-bridge connected switching elements Sw. The switching elements Sw are, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The output voltage from the inverter unit 13 is controlled by the control unit 50 controlling the switching operation of the switching elements Sw. Specifically, the voltage of the AC power output by the inverter unit 13 is controlled by the control unit 50 controlling a gate signal input to a gate terminal of the switching elements Sw.

[0031] The resonant circuit 20 includes a resonant capacitor 21 and a heating coil 22. The resonant circuit 20 is connected to the output side of the inverter unit 13 of the power conversion unit 10. The resonant capacitor 21 and the heating coil 22 are connected in series with each other on the output side of the power conversion unit 10. The resonant circuit 20 resonates with AC power at a predetermined resonant frequency. Note that the resonant circuit 20 may be configured such that multiple capacitors or multiple coils are connected in a combination of series and parallel.

[0032] The detection unit 30 detects at least one of the current and the voltage in the resonant circuit 20, which is the output target. Specifically, the detection unit 30 includes a current detector that detects the current in the resonant circuit 20. The detection unit 30 includes, for example, a CT (current transformer). The detection unit 30 outputs a detection value I a The detection unit 30 detects the AC current and outputs a signal indicating the detected value I as an AC signal to the control unit 50. a is output to the control unit 50.

[0033] The drive unit 40 outputs a drive signal to operate the power conversion unit 10 based on a signal from the control unit 50. The drive unit 40 includes a gate driver unit that outputs a gate signal to each gate terminal of the four switching elements Sw of the inverter unit 13 based on a signal input from the control unit 50.

[0034] The control unit 50 controls the AC power output from the power conversion unit 10 to the resonant circuit 20. In the first embodiment, the control unit 50 controls the AC voltage output from the inverter unit 13 of the power conversion unit 10. The control unit 50 includes, for example, a microcomputer (microcontroller) including a CPU (Central Processing Unit) and a storage device such as a flash memory. The control unit 50 executes control processing based on programs and parameters stored in the storage device. Note that the control unit 50 may be configured by a combination of multiple processors and circuits. The control unit 50 receives the detected value I from the detection unit 30 and outputs it to the resonant circuit 20. a and controls the operation of the inverter unit 13 of the power conversion unit 10 by feedback control.

[0035] As shown in FIG. 2, the control unit 50 includes a detection signal generation unit 60 and an output control unit 70. The output control unit 70 has a tracking control unit 71, a vibration suppression unit 72, and a signal generation unit 80. The control unit 50 has the detection signal generation unit 60, the output control unit 70, the tracking control unit 71, the vibration suppression unit 72, and the signal generation unit 80 as functional components. In the control unit 50, the detection signal generation unit 60, the output control unit 70, the tracking control unit 71, the vibration suppression unit 72, and the signal generation unit 80 may be configured so that their respective functions are realized by software configuration, or may be configured so that their respective functions are realized by a hardware circuit configuration that performs arithmetic processing. Furthermore, the control unit 50 may be configured so that their respective functions are realized by a combination of software and hardware.

[0036] The detection signal generating unit 60 receives the detection value I a The detection signal I F In the first embodiment, the detection signal generating unit 60 outputs the detection value I a By performing a rotational coordinate transformation process using the reference phase of the AC voltage output from the power conversion unit 10, the detected value I a A predetermined frequency component is extracted from the detection signal I and converted into two physical quantities, the d-axis component and the q-axis component. F [I d ,I q ](Detection signal I F [I d ], detection signal I F [I q ]). The detection signal generating unit 60 is configured to output the detection value I a The components obtained by excluding the specified frequency components from the signal I F The detection signal generating unit 60 is configured to output the detection signal I as [0]. The detection signal generating unit 60 generates the detection signal I from which the excluded frequency components, which are components of the frequency to be excluded that are different from the predetermined frequency components, are extracted. F As the detection signal I F The detection signal I is configured to output [0]. F[0] is the detected value I a The detection signal I F [0] is, for example, the detected value I a The detected signal I is obtained (calculated) by extracting frequency components lower than a predetermined threshold value for exclusion as excluded frequency components. F [I d ,I q The predetermined frequency component of the detection signal I is a component of the frequency (predetermined frequency) of the AC voltage output by the power conversion unit 10. The frequency of the AC voltage output from the power conversion unit 10 is set, for example, based on the resonance frequency of the resonance circuit 20. The frequency of the AC voltage is set to the value of the resonance frequency of the resonance circuit 20 or a value close to the resonance frequency. Details of the rotational coordinate transformation by the detection signal generation unit 60 will be described later. F is the detected value I a Several physical quantities (e.g., the detected signal I F [I d ], detection signal I F [I q ], detection signal I F [0]) is a general term for

[0037] The output control unit 70 detects the detected value I a The detected signal I extracted from F and the detection signal I F Output command I corresponding to multiple physical quantities R The control unit 50 is configured to generate a control signal C1 for controlling both the amplitude and phase of the AC voltage output from the power conversion unit 10 to the resonant circuit 20 based on the detected value I. The generation of the control signal C1 by the output control unit 70 will be described in detail later. a The detection signal I as a feedback quantity from F is generated by the detection signal generating unit 60, and an output command I R and the detection signal I F The output control unit 70 generates a control signal C1 for controlling the output voltage of the inverter unit 13 by performing feedback control so as to reduce the deviation (error) between the output command I Ris stored in a storage device as a preset parameter, for example.

[0038] The signal generating unit 80 generates a control signal C1 that is output from the output control unit 70. The control signal C1 is, for example, a signal that controls the phase and amplitude of the AC voltage that is output from the inverter unit 13. The signal generating unit 80 generates a tracking signal C 10 and inhibitory signal C 20 The driving unit 40 outputs a control signal C1 for operating the driving unit 40 based on the control signal C1 from the signal generating unit 80. The driving unit 40 outputs a gate signal generated based on the control signal C1 from the signal generating unit 80 to the switching element Sw of the inverter unit 13. For example, 10 and inhibitory signal C 20 A pulse signal for operating the inverter unit 13 is generated by PWM (Pulse Width Modulation) control using the control signal C1 generated based on the above as a voltage command, and the generated pulse signal is output to the drive unit 40.

[0039] (Details of control processing by the control unit) Here, as shown in FIG. 3, the detection value I a The value of I changes when a load fluctuation occurs. The load fluctuation is, for example, a change in the amount of power consumption on the load 102 side, a change in temperature, or a change in impedance. In order to respond to the load fluctuation, the control unit 50 adjusts the detected value I a Feedback control is performed using

[0040] <Calculation processing of rotation coordinate transformation> As shown in FIG. 4, the control unit 50 generates a detection value I a The detection signal generating unit 60 performs a rotational coordinate transformation operation on the detection value I a A detection signal I in which a predetermined frequency component is extracted from FIn order to generate the detection value I, a reference phase signal P(f1) corresponding to the AC voltage output from the inverter unit 13 of the power conversion unit 10 is acquired. f1 represents the frequency of the AC voltage output from the inverter unit 13. The reference phase signal P(f1) is, for example, a carrier signal that exhibits a sawtooth wave that is synchronized with the AC voltage and has the same period (frequency). The detection signal generation unit 60 acquires a reference phase that is a phase that serves as a reference for the AC voltage based on the reference phase signal P(f1). The detection signal generation unit 60 acquires the value of the sawtooth wave in the reference phase signal P(f1) as a value from 0 degrees to 360 degrees of the reference phase. Then, the detection signal generation unit 60 converts the acquired AC signal, which is the detection value I, into a reference phase value I. a is converted into an in-phase component and a quadrature component with respect to the acquired reference phase by using the reference phase signal P(f1).

[0041] The detection signal generating unit 60 generates a detection value I a By performing a rotational coordinate transformation on the reference phase, two physical quantities, a d-axis component as an in-phase component with respect to the reference phase and a q-axis component as a quadrature component with respect to the reference phase, are calculated. The detection signal generating unit 60 calculates the calculated d-axis component (I d ) and q-axis component (I q ) and the detected value I with respect to the phase (reference phase) of the AC voltage output from the inverter unit 13. a and the detected value I a The detected signal I contains both the amplitude and F A predetermined frequency component (a component of frequency f1) is extracted by a rotational coordinate transformation using the reference phase of the AC voltage output from the inverter unit 13, and a d-axis component (I d ) and q-axis component (I q ) and the detected signal I F [I d ,I q ] is generated.

[0042] The detection signal generating unit 60 also generates a detection value I a The frequency components (including DC components) lower than a predetermined frequency are extracted as excluded frequency components from the detection signal IF For example, the detection signal generating unit 60 uses a low-pass filter that passes frequencies lower than a predetermined frequency to generate the detection value I a From the detection signal I F Extract [0].

[0043] The detection signal generator 60 detects the d-axis component (I d ) and q-axis component (I q ) and the detection signal I F [I d ,I q ] and the detection signal I, which is a frequency component lower than the predetermined frequency. F [0] is output to the output control unit 70.

[0044] <Generation of Control Signals> As shown in FIG. 2, in the first embodiment, the output control unit 70 controls the tracking signal C output from the tracking control unit 71. 10 and the suppression signal C output from the vibration suppression unit 72 20 In the first embodiment, the tracking control unit 71 generates a detection signal I from which a predetermined frequency component is extracted. F [I d ,I q ] and the output command I corresponding to a given frequency component R [I d * ,I q * ], the current, which is at least one of the current and the voltage in the resonant circuit 20 (output target), is output as an output command I R The tracking signal C for tracking 10 The tracking control unit 71 is configured to output a detection signal I different from that of the vibration suppression unit 72. F and output command I R and the tracking signal C based on 10 The vibration suppression unit 72 outputs the detection signal I from which the excluded frequency components have been extracted. F [0] and the output command I corresponding to the excluded frequency components R[0], a suppression signal C for suppressing the oscillation of the current, which is at least one of the current and the voltage, in the resonant circuit 20 (output target) 20 The output control section 70 is configured to output the tracking signal C output by the tracking control section 71. 10 and the suppression signal C output by the vibration suppression unit 72 20 and generating a control signal C1 based on the

[0045] Specifically, the output control unit 70 outputs the detection signal I F [I d ,I q ] and obtain the detection signal I F d-axis component I F [I d ] and the q-axis component I F [I q ] and the corresponding output command I R [I d * ,I q * That is, in the first embodiment, the output command I R is the d-axis component I F [I d ], the target value (command value) corresponding to the output command I R [I d * ] and the q-axis component I F [I q ], the target value (command value) corresponding to the output command I R [I q * In the output control unit 70, the tracking control unit 71 converts the acquired detection signal I F and output command I R The deviation (error) between the 10 The output control unit 70 also generates the detection signal I F [0] and detect signal I F Output command I corresponding to [0] R In the output control unit 70, the vibration suppression unit 72 obtains the obtained detection signal I F [0] and output command IR The deviation (error) from [0] is calculated, and the suppression signal C is set to reduce the calculated deviation. 20 Generates an output command I R [I d * ,I q * ] is a predetermined value set to make the current in the resonant circuit 20 follow the output command I R [0] is the detected value I a (Detection signal I F ) for suppressing excluded frequency components, e.g., a zero value.

[0046] As shown in Figure 5, when a load fluctuation occurs, the detected value I a The detection signal I F The value of the detection signal I F and output command I R In the output control section 70, the tracking control section 71 and the vibration suppression section 72 detect the detection signal I F is the output command I R (deviation becomes smaller) 10 and inhibitory signal C 20 is generated.

[0047] The tracking control unit 71 performs feedback control including at least integral control to obtain the tracking signal C 10 The tracking control unit 71 is configured to output the detection signal I F and output command I R The difference between the signal C and the signal C is obtained, and integral control (I control) is performed on the obtained difference value using a predetermined integral constant. 10 The integral constant is set in advance. The tracking control unit 71 generates a tracking signal C by time integration of the acquired difference value (deviation). 10 By integral control that changes the value of the output command I R For the detection signal I F That is, the tracking control unit 71 causes the detection signal I F Output command IR Eliminate the steady-state error (offset) for

[0048] The vibration suppression unit 72 performs feedback control including at least proportional control to generate a suppression signal C 20 The vibration suppression unit 72 is configured to output the detection signal I F [0] and output command I R The difference between [0] (zero value) is obtained, and proportional control (P control) is performed on the obtained difference value using a predetermined proportional constant, thereby generating the suppression signal C 20 The proportionality constant is preset. The vibration suppression unit 72 generates a suppression signal C in proportion to the acquired difference value (deviation). 20 By proportional control, the output command I R Detection signal I due to deviation from [0] F Suppresses the vibration component of [0].

[0049] The signal generating unit 80 uses the reference phase signal P(f1) to generate the tracking signal C output by the tracking control unit 71. 10 The signal generating unit 80 converts the AC voltage command and the suppression signal C output by the vibration suppressing unit 72 into an AC voltage command. 20 The control signal C1 is generated by adding the above two signals together. The signal generating unit 80 uses the generated control signal C1 to generate a pulse signal for operating the inverter unit 13 by PWM control.

[0050] (Method of controlling AC power for a resonant circuit using a power conversion device) Next, the control process of the AC power control method for a resonant circuit by the power conversion device 100 of the first embodiment will be described with reference to Fig. 6. The control process of steps S1 to S4 in the AC power control method for a resonant circuit is executed by the control unit 50. The control process of steps S1 to S4 is repeatedly executed at predetermined control intervals.

[0051] First, in step S1, the detected value I aSpecifically, the current of the AC power in the resonant circuit 20 is detected by the detection unit 30. Then, a detection value I a is obtained as an output from the detection unit 30.

[0052] Next, in step S2, the detection signal I F Specifically, the detected value I obtained in step S1 is output. a Detection signal I, in which multiple physical quantities are extracted from F The detection signal I is output. F is the detected value I a The detected signal I is extracted as a predetermined frequency component from F [I d ,I q ] and the detected signal I extracted as components other than the specified frequency components (exclusion frequency components). F Includes [0].

[0053] Next, in step S3, a control signal C1 is generated. Specifically, the detection signal I F The detection signal I F [I d ,I q ] and the output command I corresponding to this physical quantity R The output command I R [I d * ,I q * ] and based on the tracking signal C 10 is generated. The tracking signal C 10 is the current in the resonant circuit 20 as an output command I R The signal is used to follow the detected signal I F The detection signal I F [0] and the output command I corresponding to this physical quantity R [0], the suppression signal C for removing components (exclusion frequency components) other than the predetermined frequency components in the resonant circuit 20 20 is generated. The tracking signal C 10 is the output command I RDetection signal I F [I d ,I q ] is generated by a regulator operation such as integral control based on the deviation of 20 is the output command I R Detection signal I F The signal generator 80 generates the tracking signal C 10 and inhibitory signal C 20 is converted into a format that can be input to the driver 40. The signal generator 80 generates the tracking signal C using the reference phase signal P(f1), for example. 10 is converted into an AC voltage command, and the converted AC voltage command is applied with an inhibition signal C 20 is added to generate a control signal C1, which is a voltage command.

[0054] Next, in step S4, a signal is output from the signal generating unit 80 to the driving unit 40. The control signal C1 is converted into a pulse signal for controlling the switching of the switching element Sw, and is output to the driving unit 40 which operates the switching element Sw.

[0055] [Effects of the first embodiment] In the first embodiment, the following effects can be obtained.

[0056] In the first embodiment, as described above, the detection signal I calculated as a plurality of physical quantities is F and the detection signal I F Output command I corresponding to multiple physical quantities R Based on this, a control signal C1 is generated to control both the amplitude and phase of the voltage or current in the AC power output to the resonant circuit 20 (output target). The control signal C1 suppresses oscillation of the resonant current in the resonant circuit 20 (output target) and also controls the output command I RThis allows the control signal C1 to control both the amplitude and phase of the voltage or current of the AC power, thereby improving the responsiveness of the control to the load fluctuation when a load fluctuation such as a fluctuation in impedance occurs in the resonant circuit 20. Therefore, unlike when the control responsiveness is low, it is possible to prevent the control from becoming unstable even when a load fluctuation occurs. As a result, when controlling the AC power output to the resonant circuit 20, it is possible to improve the stability of the resonant state of the AC power in the resonant circuit 20.

[0057] Furthermore, when controlling AC power output to an output target including the resonant circuit 20, the amplitude and frequency of the current or voltage of the AC power output from the inverter unit 13 may be controlled. In this case, the phase cannot be directly controlled by controlling the frequency, and therefore the control responsiveness to load fluctuations decreases. In contrast, in the power conversion device 100 according to the first embodiment, the control signal C1 controls both the amplitude and phase of the AC voltage output from the inverter unit 13, and therefore the control responsiveness to load fluctuations can be improved. Therefore, the stability of the resonant state of the AC power in the resonant circuit 20 can be improved compared to when frequency is controlled.

[0058] In the first embodiment, as described above, the output control unit 70 controls the detection signal I F and output command I R and based on the detected value I a At least one of the current and voltage in the output target corresponding to the output command I R The tracking signal C for tracking 10 The output control unit 70 also has a tracking control unit 71 configured to output the detected value I a Suppression signal C for suppressing oscillation of at least one of current and voltage in the output target corresponding to 20 The output control unit 70 includes a vibration suppression unit 72 configured to output a follow-up signal C output from the follow-up control unit 71. 10 and the suppression signal C output from the vibration suppression unit 7220 The output control unit 70 generates a control signal C1 based on the output command I. R Follow-up signal C to follow 10 and a suppression signal C for suppressing vibrations of at least one of the current and the voltage in the output target. 20 Since the output control unit 70 has a vibration suppression unit 72 that outputs an output command I, the control signal C1 from the output control unit 70 suppresses vibration of at least one of the current and voltage in the output target and R Therefore, the resonant current in the resonant circuit 20 can be controlled to follow the output command I R Since the resonant state of the AC power in the resonant circuit 20 can be made more stable by adjusting the resonant state of the AC power in the resonant circuit 20, the stability of the resonant state of the AC power in the resonant circuit 20 can be further improved.

[0059] In the first embodiment, as described above, the tracking control unit 71 receives a detection signal I different from that of the vibration suppression unit 72. F and output command I R and the tracking signal C based on 10 This allows the tracking control unit 71 and the vibration suppression unit 72 to independently control the AC power in the resonant circuit 20. Therefore, the tracking control unit 71 and the vibration suppression unit 72 output a common detection signal I F In comparison with the case where the resonant circuit 20 is used, the resonant state of the AC power in the resonant circuit 20 can be made more stable.

[0060] In the first embodiment, as described above, the tracking control unit 71 performs feedback control including at least integral control to obtain the tracking signal C 10 As a result, the tracking control unit 71 performs integral control to output the output command I R By suppressing the steady-state error of the detection signal I F Output command I R Since the resonant state of the AC output in the resonant circuit 20 can be controlled more stably, the resonant state of the AC output in the resonant circuit 20 can be controlled more stably.

[0061] In the first embodiment, as described above, the vibration suppression unit 72 performs feedback control including at least proportional control to suppress the suppression signal C 20 As a result, the vibration suppression unit 72 outputs the detection signal I F Since the vibration component in the resonant circuit 20 can be suppressed by proportional control, the resonant state of the AC output in the resonant circuit 20 can be controlled more stably.

[0062] In the first embodiment, as described above, the detection signal generating unit 60 generates the detection values ​​I a A predetermined frequency component is extracted from the signal I F As a result, the detected value I a Even if multiple frequency components are included in the signal I, the signal I is extracted as a specific frequency component. F As a result, the control signal C1 can be generated so that the AC power is more stable, and as a result, the stability of the resonant state of the AC power in the resonant circuit 20 can be further improved.

[0063] In the first embodiment, as described above, the detection signal generating unit 60 generates the detection signal I F This allows the detection signal I, which is the frequency component of the AC voltage output from the power conversion unit 10, to be extracted. F Therefore, the control signal C1 for controlling the AC power can be generated, and the AC power can be output more stably. As a result, the stability of the resonant state of the AC power in the resonant circuit 20 can be further improved. In addition, the detection signal generating unit 60 uses the detection value I as a plurality of physical quantities. a A predetermined frequency component is extracted from the detection signal I and converted into two physical quantities, the d-axis component and the q-axis component. F [I d ,I q ] and frequency components lower than a predetermined frequency (including DC components) are extracted, and the detection signal IF Therefore, the detection signal I from which the predetermined frequency component is extracted is output as [0]. F [I d ,I q ] and the detection signal I in which frequency components lower than the specified frequency are extracted. F By using [0], the control signal C1 can be generated so that the AC power is more stable. As a result, the stability of the resonant state of the AC power in the resonant circuit 20 can be further improved.

[0064] In the first embodiment, as described above, the detection signal generating unit 60 generates the detection signal I F [I d ,I q ] and a detection signal I in which excluded frequency components, which are components of frequencies to be excluded that are different from the predetermined frequency components, are extracted. F The tracking control unit 71 is configured to output a detection signal I from which a predetermined frequency component has been extracted. F [I d ,I q ] and the output command I corresponding to a given frequency component R [I d * ,I q * ] and the tracking signal C based on 10 The vibration suppression unit 72 is configured to output the detection signal I from which the excluded frequency components have been extracted. F [0] and the output command I corresponding to the excluded frequency component R [0] and the suppression signal C 20 This allows for separate control of the predetermined frequency component and the excluded frequency component (a frequency component lower than the predetermined frequency), which is a frequency component to be excluded that is different from the predetermined frequency component. Therefore, even if vibration of the excluded frequency component occurs in the output target due to load fluctuations or the like, the excluded frequency component can be effectively suppressed. As a result, the stability of the resonant state of the AC power in the resonant circuit 20 can be further improved.

[0065] In the first embodiment, as described above, the detection signal generating unit 60 generates the detection value I a By performing a rotational coordinate transformation using the reference phase of the voltage or current in the AC power output from the power conversion unit 10, the detected value I a A predetermined frequency component is extracted from the detection signal I and converted into two physical quantities, the d-axis component and the q-axis component. F [I d ,I q ] is output. By performing the calculation process of the rotation coordinate transformation, the detected value I a can be easily converted into two physical quantities, the d-axis component and the q-axis component, extracted as frequency components of the voltage or current of the AC power. Therefore, the control signal C1 for further stabilizing the AC power can be easily generated, and the stability of the resonant state of the AC power in the resonant circuit 20 can be easily further improved.

[0066] [Second embodiment] Next, the configuration of a power conversion device 200 according to a second embodiment will be described with reference to Fig. 7. In the second embodiment, an output control section 270 in a control section 250 generates a correction signal C 230 The same components as those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

[0067] (Configuration of power conversion device according to second embodiment) As shown in Fig. 7, the power conversion device 200 according to the second embodiment includes a power conversion unit 10, a resonant circuit 20, a detection unit 30, a drive unit 40, and a control unit 250. The control unit 250 includes an output control unit 270. The output control unit 270 has a characteristic input unit 273 in addition to a tracking control unit 71, a vibration suppression unit 72, and a signal generation unit 280. The power conversion device 200 is an example of a "power conversion device for a resonant circuit" in the claims.

[0068] In the second embodiment, the characteristic input unit 273 receives a correction signal C230 The control unit 250 is configured to output a preset correction signal C 230 In the resonant circuit 20, which is the output target, the detected value I a At least one of the current and the voltage corresponding to the correction signal C 230 is the detected value I due to a change in the output target a Change in the detection signal I F The time is preset and stored so as to correspond to the change in the time.

[0069] As a specific event, for example, when a load fluctuation occurs in the resonant circuit 20 that is the output target, or when an output command I R When the detected value I a The control unit 250 may calculate the detected value I in accordance with the characteristic of the output object for a specific event. a The tracking signal C is adjusted to reduce the change in 10 Correction signal C to correct 230 For example, the output command I R When a specific event such as a change from 50% to 100% or a load fluctuation on the load 102 side is detected, the control unit 250 outputs a detection signal I F In addition to the correction signal C 230 Correction command signal S for outputting a is output to the output control unit 270. The output correction command signal S a is input to the characteristic input unit 273. The control unit 250 generates a correction command signal S based on an input signal from outside the device or an input signal from a temperature sensor or the like separate from the detection unit 30. a Also, the detected value I a or detection signal I F When a large change in is detected, the correction signal C 230 Correction command signal S for outputting a The characteristic input unit 273 may output the input correction command signal Sa Based on this, the tracking signal C 10 Correction signal C to correct 230 Outputs the correction signal C 230 may be a constant fixed value, or may be a correction command signal S a The value may vary depending on

[0070] In the second embodiment, the output control unit 270 outputs the tracking signal C 10 and the correction signal C from the characteristic input unit 273 230 and the corrected tracking signal C 210 The output control section 270 is configured to generate the correction signal C 230 The tracking signal C corrected by 210 and the inhibitory signal C 20 Specifically, the output control unit 270 receives the correction signal C from the characteristic input unit 273 and generates the control signal C1 based on the correction signal C. 230 When is output, the correction signal C 230 The tracking signal C 10 and the corrected tracking signal C 210 The tracking signal C 10 and inhibitory signal C 20 The output of the correction signal C is the same as that of the first embodiment. 230 and follow-up signal C 10 By adding and processing, the tracking signal C 10 The corrected tracking signal C 210 Then, the signal generating unit 280 generates the corrected tracking signal C 210 and inhibitory signal C 20 The control unit 250 generates the control signal C1 based on the detected value I, similarly to the signal generating unit 80 of the first embodiment. The control process of the inverter unit 13 of the power conversion unit 10 using the generated control signal C1 is the same as in the first embodiment. a The detected signal I extracted from F In addition to the feedback control using a Based on this, the detection signal I FThe other configurations of the second embodiment are the same as those of the first embodiment.

[0071] [Effects of the second embodiment] In the second embodiment, the following effects can be obtained.

[0072] In the second embodiment, as described above, the output control section 270 generates a correction signal C 230 The output control section 270 has a characteristic input section 273 configured to output the suppression signal C 20 and the correction signal C from the characteristic input unit 273 230 The tracking signal C corrected by 210 The control signal C1 is generated based on the detected value I a A correction signal C preset in response to a change in at least one of the current and the voltage corresponding to 230 By using this, the detected value I a The tracking signal C 10 Therefore, the detected value I a At least one of the current and voltage corresponding to the output command I R This allows the inverter 20 to follow the AC power more responsively, thereby further improving the stability of the resonant state of the AC power in the resonant circuit 20. Other effects of the second embodiment are the same as those of the first embodiment.

[0073] [Third embodiment] Next, the configuration of a power conversion device 300 according to a third embodiment will be described with reference to Fig. 8. In the third embodiment, an output control section 370 in a control section 350 outputs a startup tracking signal C 310 The second embodiment has a start-up control unit 374 that outputs the following: The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0074] (Configuration of power conversion device according to third embodiment) As shown in Fig. 8, a power conversion device 300 according to the third embodiment includes a power conversion unit 10, a resonant circuit 20, a detection unit 30, a drive unit 40, and a control unit 350. The control unit 350 includes an output control unit 370. The output control unit 370 has a start-up control unit 374 in addition to a tracking control unit 71, a vibration suppression unit 72, and a signal generation unit 380. The output control unit 370 also has a change-over switch 375a and a change-over switch 375b. The power conversion device 300 is an example of a "power conversion device for a resonant circuit" in the claims.

[0075] In the third embodiment, the start-up control unit 374 generates a tracking signal C 10 In addition to the start-up tracking signal C 310 The start-up tracking signal C is output. 310 is set in advance and stored as a predetermined voltage command value. In the third embodiment, the output control unit 370 receives the startup tracking signal C from the startup control unit 374 at startup. 310 The output control section 370 outputs the tracking signal C by the changeover switch 375a. 10 and startup tracking signal C 310 The output control section 370 also outputs either the suppression signal C or the suppression signal C by the changeover switch 375b. 20 or a zero value signal [0]. 10 and inhibitory signal C 20 The process of generating is the same as in the first embodiment.

[0076] The output control unit 370 switches between the changeover switches 375a and 375b for a predetermined period of time from the start of the power conversion unit 10, thereby controlling the detected value I a The detected signal I extracted from F (Detection signal I F [I d ,I q ] and I F [0]) without using the startup tracking signal C from the startup control unit 374 310 Only the start-up tracking signal C is output. 310 is the tracking signal C10, Inhibition signal C 20 Similarly to the signal C , the signal C is a voltage command signal for controlling both the amplitude and phase of the AC voltage output from the power conversion unit 10, and is input from the output control unit 370 to the signal generation unit 380. The output control unit 370 switches between the changeover switches 375 a and 375 b to control the start-up tracking signal C from the start-up control unit 374 for a predetermined period from the start-up of the power conversion unit 10. 310 and a zero value signal [0] are input to the signal generating unit 380. The zero value signal [0] is a signal indicating a value of 0. The signal generating unit 380, like the signal generating unit 80 of the first embodiment, generates the startup tracking signal C 310 That is, the signal generating unit 380 generates a control signal C1 for controlling the inverter unit 13 of the power conversion unit 10 based on the startup tracking signal C 310 into an AC voltage command, and adds a zero value signal [0] to the converted AC voltage command to generate a control signal C1, which is a voltage command. Therefore, in the third embodiment, the signal generating unit 380 generates the startup tracking signal C 310 The AC voltage command converted from the above is output as the control signal C1.

[0077] In the third embodiment, the output control unit 370 receives the startup follow-up signal C from the startup control unit 374 at startup. 310 After outputting the control signal C1 generated based on F and output command I R The control signal C1 (following signal C 10 and inhibitory signal C 20 After a predetermined period of time has elapsed since the start-up of the power conversion unit 10, the output control unit 370 switches between the changeover switches 375a and 375b to output a control signal C1) corresponding to the start-up tracking signal C from the start-up control unit 374. 310 Stop the output of the follow-up signal C 10 and the suppression signal C20. The changeover switches 375a and 375b output a control signal C1 based on the detection signal I instead of a predetermined period. F Based on this, the detected value I aFor example, when the detected value I a When the effective value or average value of exceeds a predetermined threshold, the detection value I a The changeover switches 375a and 375b may be switched when it is determined that the voltage Vcc has stabilized. The other configurations of the third embodiment are the same as those of the first embodiment.

[0078] [Effects of the third embodiment] In the third embodiment, the following effects can be obtained.

[0079] In the third embodiment, as described above, the output control unit 370 outputs the tracking signal C 10 In addition to the start-up tracking signal C 310 The output control section 370 also has a start-up control section 374 configured to output a start-up follow-up signal C from the start-up control section 374 at the time of start-up. 310 After outputting the control signal C1 generated based on F and output command I R The control signal C1 (following signal C 10 and inhibitory signal C 20 The control signal C1 is outputted by the control signal C2. 10 Start-up tracking signal C is output separately from 310 Based on this, control at the time of startup of the power conversion unit 10 is performed, so that the detected value I a Even when the temperature is not stable, the control can be stably executed. Note that the other effects of the third embodiment are the same as those of the first embodiment.

[0080] [Fourth embodiment] Next, the configuration of a power conversion device 400 according to a fourth embodiment will be described with reference to Fig. 9 and Fig. 10. In the fourth embodiment, the reference phase is corrected by a detection signal generation unit 460. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0081] (Configuration of power conversion device according to fourth embodiment) As shown in Fig. 9, a power conversion device 400 according to the fourth embodiment includes a power conversion unit 10, a resonant circuit 20, a detection unit 30, a drive unit 40, and a control unit 450. The control unit 450 includes a detection signal generation unit 460. The detection signal generation unit 460 generates a detection value I, which is an AC signal, in the same manner as in the first embodiment. a By performing a rotational coordinate transformation using the reference phase of the AC voltage frequency, the detected value I a The output frequency component is extracted from the detection signal I and converted into two physical quantities, the d-axis component and the q-axis component. F (Detection signal I F [I d ,I q ]). The detection signal generating unit 460 is configured to output the detection value I a The detection signal I from which the frequency components are extracted (components other than the specified frequency components) are excluded. F The power converter 400 is configured to output a signal as [0]. The power converter 400 is an example of the "power converter for a resonant circuit" in the claims.

[0082] Here, as shown in FIG. 10, the detection operation in the detection unit 30 and the detection value I a For example, there may be a delay in the control operation when acquiring the current I a0 In this case, when a rotational coordinate transformation is performed based on the phase of the AC voltage, a phase shift occurs due to the delay, and therefore, when extracting a predetermined frequency component, the detected value Ia is detected with a delay of a predetermined frequency component. FTherefore, in the fourth embodiment, the reference phase of the acquired AC voltage is corrected to eliminate the phase shift caused by the delay in the detection operation and the delay in the control (dead time), and the rotational coordinate transformation is performed based on information indicating the corrected reference phase. In the fourth embodiment, the detection signal generation unit 460 corrects the reference phase based on the delay correction amount θ0 corresponding to the delay amount relative to the reference phase, and calculates the detection value I a By performing a rotational coordinate transformation using the reference phase corrected by the delay correction amount θ0, a detection signal I F (Detection signal I F [I d ,I q ]) is configured to output.

[0083] Specifically, the detection signal generating unit 460 generates the detection value I a A detection signal I in which a predetermined frequency component is extracted from F In order to generate the reference phase signal P(f1), the detection signal generating unit 460 acquires a reference phase signal P(f1) corresponding to the frequency of the AC voltage output from the inverter unit 13 of the power converting unit 10. In the fourth embodiment, the detection signal generating unit 460 acquires a delay correction amount θ0 for correcting a delay with respect to the reference phase signal P(f1). The detection signal generating unit 460 corrects the reference phase signal P(f1) by shifting the phase of the reference phase signal P(f1) by the acquired delay correction amount θ0. The delay correction amount θ0 is, for example, set in advance and stored as a parameter in a storage device. The delay correction amount θ0 may be a fixed value set in advance, or may be changed depending on the control conditions or the state of the output target (load).

[0084] The detection signal generator 460 generates the corrected reference phase signal P(f1) and the detection value I a By using the above, the rotation coordinate transformation is performed in the same manner as in the first embodiment, and the detection signal I F That is, the detection signal generating unit 460 generates the detection value I aIn the rotational coordinate transformation for the detection signal I, the d-axis component as the in-phase component with respect to the reference phase with the delay corrected by the delay correction amount θ0 and the q-axis component as the quadrature component with respect to the reference phase with the delay corrected are calculated. F (Detection signal I F [I d ,I q ]) to generate the detection signal I F The tracking signal C by feedback control using 10 The generation of is the same as in the first embodiment. The other configurations of the fourth embodiment are the same as in the first embodiment.

[0085] [Effects of the fourth embodiment] In the fourth embodiment, the following effects can be obtained.

[0086] In the fourth embodiment, as described above, the detection signal generation unit 460 generates the detection value I a The reference phase is corrected based on the delay correction amount θ0 corresponding to the delay amount relative to the reference phase of the detection value I a By performing a rotational coordinate transformation using the reference phase corrected by the delay correction amount θ0, the detection signal I F Here, when a delay occurs in the detection process or the control process, the acquired detection value I a In this case, it is considered that the accuracy of extracting the predetermined frequency component is reduced due to the phase shift. Taking this into consideration, in the fourth embodiment, the detection value I a The reference phase is corrected based on the delay correction amount θ0 corresponding to the delay amount relative to the reference phase of the detection value I a Even if there is a phase shift in the frequency components, it is possible to prevent the accuracy of the extracted frequency components from decreasing. The other effects of the fourth embodiment are the same as those of the first embodiment.

[0087] [Fifth embodiment] Next, the configuration of a power conversion device 500 according to a fifth embodiment will be described with reference to Fig. 11. In the fifth embodiment, a detection signal I F Unlike the first embodiment in which the detection signal I is generated, the detection signal I is converted into an amplitude component and a phase difference component by the detection signal generating unit 560 of the control unit 550. F [I T ,I P ] is generated. Note that the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0088] (Configuration of power conversion device according to fifth embodiment) As shown in Fig. 11, the power conversion device 500 according to the fifth embodiment includes a power conversion unit 10, a resonant circuit 20, a detection unit 30, a drive unit 40, and a control unit 550. The control unit 550 includes a detection signal generation unit 560. As in the first embodiment, the detection signal generation unit 560 generates a detection value I a A detection signal I in which a predetermined frequency component is extracted and converted into multiple physical quantities F The power conversion device 500 is an example of the "power conversion device for a resonant circuit" in the claims.

[0089] In the fifth embodiment, the detection signal generation unit 560 generates a detection value I a , the detected value I a The amplitude component I indicates the amplitude of F [I T ] and the detected value I for the reference phase of the AC voltage a Phase difference component I, which indicates the phase difference of F [I P ] and the detected signal I is extracted as a predetermined frequency component by converting it into two physical quantities. F [I T ,I P The detection signal generating unit 560 is configured to output the acquired detection value I a By performing amplitude and phase calculations on the detected signal I F Generate.

[0090] In the amplitude and phase calculation, the detection signal generation unit 560 calculates the detection value I a The detection signal generating unit 560 calculates the amplitude of a predetermined frequency component and the phase difference with the AC voltage from the acquired detection value I a For example, by performing a fast Fourier transform (FFT) on the detected value I a Then, the detection signal generating unit 560 calculates the amplitude component of the voltage waveform of the AC voltage and the acquired detection value I a That is, in the fifth embodiment, the phase of the voltage waveform of the AC voltage is acquired as the reference phase of the predetermined frequency. Then, the detection signal generating unit 560 calculates the phase difference between the detection value I a The phase difference is calculated as a phase difference component. The phase difference is calculated, for example, by acquiring the zero crossing point where the AC signal becomes zero. The detection signal generation unit 560 obtains the amplitude component and the phase difference component obtained by the amplitude-phase calculation described above, and calculates the detection value I a A detection signal I is extracted from a specific frequency component and converted into two physical quantities. F (Detection signal I F [I T ,I P ]).

[0091] In the fifth embodiment, a detection signal I including an amplitude component and a phase difference component is F is output to the output control unit 70. In addition, the detection signal I F Output command I corresponding to R That is, in the fifth embodiment, the output command I R are the target values ​​(command values) corresponding to the amplitude component and the phase difference component, respectively. R [I T * ,I P * As in the first embodiment, the output control unit 70 converts the input detection signal I F and output command I R and the tracking signal C based on 10By generating the control signal C1 for controlling both the amplitude and phase of the AC voltage, the fifth embodiment has the same configuration as the first embodiment in other respects.

[0092] [Effects of the fifth embodiment] In the fifth embodiment, the following effects can be obtained.

[0093] In the fifth embodiment, as described above, the detection signal generation unit 560 generates the detection value I a , the detected value I a and the detected value I a and a phase difference component that indicates the phase difference between the two physical quantities, and a detection signal I F This converts the detected value I into two physical quantities, the amplitude component and the phase difference component. a Therefore, the detected signal I F By the following signal C 10 can be generated, so the tracking signal C 10 The amplitude and phase of the AC voltage can be controlled with higher precision by the control signal C1 generated based on the above. Note that other effects of the fifth embodiment are similar to those of the first embodiment.

[0094] [Sixth embodiment] Next, the configuration of a power conversion device 600 according to a sixth embodiment will be described with reference to Fig. 12. In the sixth embodiment, a detection signal generating unit 660 of a control unit 650 generates a detection value I a Preliminary detection signal I using the effective value of F2 The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0095] (Configuration of power conversion device according to sixth embodiment) As shown in Fig. 12, a power conversion device 600 according to the sixth embodiment includes a power conversion unit 10, a resonant circuit 20, a detection unit 30, a drive unit 40, and a control unit 650. The control unit 650 includes a detection signal generation unit 660 and an output control unit 670. The detection signal generation unit 660 generates a detection signal I F [0] and preliminary detection signal I F2 and a detection signal I F The output control section 670 is configured to output the tracking signal C 610 and a tracking control unit 671 that generates an inhibition signal C 20 The vibration suppression unit 72 and the signal generation unit 680 generate the tracking signal C. 610 and inhibitory signal C 20 is input to the signal generating unit 680. The power conversion device 600 is an example of the "power conversion device for a resonant circuit" in the claims.

[0096] In the sixth embodiment, the detection signal generating unit 660 generates the detection signal I F As the detected value I a The detection signal I of the excluded frequency components, which is the components (components other than the specified frequency components) obtained by excluding the specified frequency components from F The detection signal generating unit 660 is configured to output [0]. As in the first embodiment, the detection signal generating unit 660 generates the detection value I a From the detection signal I F [0]. The detection signal generation unit 660 extracts the detection signal I F In addition to [0], the detected value I a A preliminary detection signal I indicating one physical quantity including at least one of the effective value, average value, and peak value of F2 Detect signal I F Specifically, the detection signal generating unit 660 outputs the detection value I a The detected value I a is converted into a single physical quantity, the preliminary detection signal I F2 Then, the generated detection signal I F [0] and preliminary detection signal I F2The detection signal generating unit 660 outputs the preliminary detection signal I to the output control unit 670. F2 is output to the tracking control section 671 of the output control section 670, and the detection signal I F [0] is output to the vibration suppression unit 72.

[0097] The tracking control unit 671 receives the preliminary detection signal I F2 and preliminary detection signal I F2 Output command I corresponding to R The preliminary output command I R2 and based on the tracking signal C 610 The vibration suppression unit 72 is configured to output the detection signal I F [0] and output command I R [0] and based on the suppression signal C 20 The preliminary detection signal I F2 Reserve output command I corresponding to R2 is the detected value I a That is, in the sixth embodiment, the tracking control unit 671 controls the tracking signal C based on an input different from that of the tracking control unit 71 in the first embodiment. 610 The tracking control unit 671 outputs a preliminary detection signal I F2 and spare output command I R2 and the tracking signal C based on 610 The output of the detection signal I F and output command I R and the tracking signal C based on 10 Then, the signal generating unit 680 performs the same processing as in the first embodiment to generate the tracking signal C output by the tracking control unit 671. 610 and the suppression signal C output by the vibration suppression unit 72 20 Based on this, the control signal C1 is output to operate the drive unit 40. Other configurations of the sixth embodiment are the same as those of the first embodiment.

[0098] [Effects of the sixth embodiment] In the sixth embodiment, the following effects can be obtained.

[0099] In the sixth embodiment, as described above, the detection signal generating unit 660 generates the detection value I a A preliminary detection signal I indicating one physical quantity including at least one of the effective value, average value, and peak value of F2 The detection signal I F The tracking control unit 671 is configured to output a preliminary detection signal I F2 and the corresponding spare output command I R2 and based on the tracking signal C 610 As in the first embodiment, the vibration suppression unit 72 is configured to output the detection signal I F [0] and the detection signal I F Output command I corresponding to [0] R [0] and based on the suppression signal C 20 This outputs the output command I R The tracking signal C for tracking 610 , the detected value I a A preliminary detection signal I indicating one physical quantity including the effective value of F2 Even when outputting based on the detection signal I F By using a tracking signal C to control both the amplitude and phase of the AC voltage, 610 and inhibitory signal C 20 Therefore, it is possible to stabilize the control of the AC voltage output to the resonant circuit 20. a The detected value I a At least one of the current and voltage in the output target corresponding to the output command I R Even when the sixth embodiment is made to follow the frequency of the AC power, it is possible to improve the stability of the resonant state of the AC power in the resonant circuit 20. Other effects of the sixth embodiment are the same as those of the first embodiment.

[0100] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0101] For example, in the first to sixth embodiments described above, examples have been shown in which the AC voltage output from the power conversion unit 10 is controlled, but the present invention is not limited to this. In the present invention, the AC current output from the power conversion unit 810 may be controlled, as in the power conversion unit 810 according to a modification of the first embodiment shown in Fig. 13. In this case, the detection unit 830 may acquire a detection value obtained by detecting the voltage in a resonant circuit 820 in which a resonant coil and a resonant capacitor are connected in parallel to each other.

[0102] In the first to sixth embodiments, the power converters 100, 200, 300, 400, 500, and 600 (resonant circuit power converters) are induction heating devices constituting electric resistance welded pipe welding equipment. An example has been described in which AC power is output from the power conversion unit 10 to a resonant circuit 20 including a heating coil 22 as an output target. However, the present invention is not limited to this. In the present invention, the resonant circuit power converter may output AC power to a heating coil of an induction furnace. Alternatively, the power converter may output AC power to an output target including a resonant circuit having a resonant coil other than a heating coil. The output target may be connected to the power conversion unit in a non-contact manner. In this case, a detected value of the non-contact connected output target may be acquired to control both the amplitude and phase of the current or voltage in the output AC power. The detected value may be either the current or the voltage of the output target, or both.

[0103] In the first to sixth embodiments, examples have been shown in which the power converters 100, 200, 300, 400, 500, and 600 (power converters for resonant circuits) include the resonant circuit 20 and the detection unit 30, but the present invention is not limited to this. In the present invention, the detection unit may be arranged separately from the power converter for resonant circuits. For example, the detection unit may be arranged in an external load device as an output target, and a signal indicating a detection value as a detection result by the detection unit may be acquired from the external load device. Furthermore, the resonant circuit may be arranged in the external load device as an output target.

[0104] Furthermore, in the above-described first to sixth embodiments, examples have been shown in which the output control units 70, 270, 370, and 670 have at least a tracking control unit that performs integral control and a vibration suppression unit that performs at least proportional control, but the present invention is not limited to this. In the present invention, the output control unit does not need to have a tracking control unit that performs integral control. For example, when the steady-state deviation (offset) of the detection signal with respect to the output command is a predetermined value, integral control may not be performed, and a tracking signal may be generated and output by feedforward control. Furthermore, the vibration suppression unit may perform integral control in addition to proportional control. Furthermore, the tracking control unit may perform proportional control in addition to integral control. Furthermore, the output control unit may perform differential control.

[0105] In the first to sixth embodiments, the detection signal I is generated by extracting a predetermined frequency component of the AC voltage by the detection signal generating units 60, 460, 560, and 660. F However, the present invention is not limited to this. In the present invention, the detection signal generating unit may generate a detection signal different from the predetermined frequency component. For example, a detection signal may be generated in which a frequency component having a frequency n times or 1 / n (n: integer) of the predetermined frequency component is extracted.

[0106] In the third embodiment, the detection signal I F In addition to this, a start-up tracking signal C from the start-up control unit 374 310After outputting the tracking signal C from the tracking control unit 71, 10 However, the present invention is not limited to this. In the present invention, at startup, both the startup tracking signal and the startup tracking signal from the startup control unit may be used to perform startup control. For example, startup control may be performed using a signal obtained by adding the startup tracking signal from the startup control unit and the tracking signal from the tracking control unit.

[0107] In the sixth embodiment, the detection signal generating unit 660 is configured to generate the detection value I a The preliminary detection signal I is a physical quantity containing the effective value of F2 However, the present invention is not limited to this. In the present invention, the detection signal generating unit may be configured to output a preliminary detection signal that is a single physical quantity including at least one of the effective value, average value, and peak value of the detection value. Alternatively, the preliminary detection signal may be output by combining the effective value, average value, and peak value of the detection value. For example, the preliminary detection signal may be calculated by acquiring multiple peak values ​​and calculating the average value of the acquired multiple peak values.

[0108] In the first to fifth embodiments, the detected values ​​I a A detection signal I extracted from a specified frequency component F The tracking control unit 71 outputs the tracking signal C 10 However, the present invention is not limited to this. In the present invention, a detection signal I F The vibration suppressor may generate the suppression signal by: [Explanation of symbols]

[0109] 10, 810 Power conversion unit 20, 820 resonant circuit 50, 250, 350, 450, 550, 650 Control unit 60, 460, 560, 660 Detection signal generator 70, 270, 370, 670 Output control section 71, 671 Tracking control section 72 Vibration suppressor 100, 200, 300, 400, 500, 600 Power conversion equipment 273 Characteristics input section 374 Start control unit

Claims

1. a power conversion unit that outputs AC power to an output target including a resonant circuit; a control unit that controls the AC power output from the power conversion unit, The control unit a detection signal generating unit configured to output, as detection signals, a plurality of physical quantities calculated from a detection value of at least one of a current and a voltage in the output target including the resonant circuit; an output control unit configured to generate a control signal for controlling both the amplitude and phase of a voltage or current in the AC power output to the resonant circuit, based on the detection signal and an output command corresponding to a plurality of physical quantities of the detection signal.

2. The output control unit a vibration suppression unit configured to output a suppression signal for suppressing vibration of at least one of a current and a voltage in the output object corresponding to the detection value, based on the detection signal and the output command; a tracking control unit configured to output a tracking signal for causing at least one of a current and a voltage in the output object corresponding to the detection value to follow the output command, 2. The power conversion device for a resonant circuit according to claim 1, wherein the control signal is generated based on the suppression signal output by the vibration suppression unit and the tracking signal output by the tracking control unit.

3. 3. The power converter for a resonant circuit according to claim 2, wherein the tracking control unit is configured to output the tracking signal based on the detection signal different from that of the vibration suppression unit and the output command.

4. 4. The power converter for a resonant circuit according to claim 2, wherein the vibration suppressor is configured to output the suppression signal by performing feedback control including at least proportional control.

5. 4. The power converter for a resonant circuit according to claim 2, wherein the tracking control section is configured to output the tracking signal by performing feedback control including at least integral control.

6. The output control unit a characteristic input unit configured to output a preset correction signal corresponding to the characteristic of the output object; 4. The power conversion device for a resonant circuit according to claim 2, wherein the control signal is generated based on the suppression signal and the tracking signal corrected by the correction signal from the characteristic input unit.

7. The output control unit a startup control unit configured to output a set startup tracking signal separately from the tracking signal when the power conversion unit is started, 4. The power conversion device for a resonant circuit according to claim 2, wherein the power conversion device is configured to output the control signal generated based on the startup tracking signal from the startup control unit at startup, and then output the control signal generated based on the detection signal and the output command.

8. 4. The power conversion device for a resonant circuit according to claim 2, wherein the detection signal generation unit is configured to extract predetermined frequency components from the detection values ​​as the plurality of physical quantities, and output the extracted predetermined frequency components as the detection signal.

9. 9. The power conversion device for a resonant circuit according to claim 8, wherein the detection signal generation unit is configured to extract the detection signal having a frequency component of a voltage or a current of the AC power output from the power conversion unit as the predetermined frequency component.

10. the detection signal generation unit is configured to output the detection signal from which the predetermined frequency component is extracted and the detection signal from which an exclusion frequency component, which is a component of an exclusion target frequency different from the predetermined frequency component, is extracted; the tracking control unit is configured to output the tracking signal based on the detection signal from which the predetermined frequency component has been extracted and the output command corresponding to the predetermined frequency component, 9. The power conversion device for a resonant circuit according to claim 8, wherein the vibration suppression unit is configured to output the suppression signal based on the detection signal from which the excluded frequency component is extracted and the output command corresponding to the excluded frequency component.

11. 10. The power conversion device for a resonant circuit according to claim 9, wherein the detection signal generation unit is configured to perform a rotational coordinate transformation operation on the detection value using a reference phase of a voltage or a current in the AC power output from the power conversion unit, thereby extracting the predetermined frequency component from the detection value and converting it into two physical quantities, a d-axis component and a q-axis component, to output the detection signal.

12. 12. The power conversion device for a resonant circuit according to claim 11, wherein the detection signal generation unit is configured to correct the reference phase based on a delay correction amount corresponding to a delay of the detection value relative to the reference phase, and to output the detection signal by performing a rotational coordinate transformation operation using the reference phase corrected by the delay correction amount.

13. 9. The power conversion device for a resonant circuit according to claim 8, wherein the detection signal generation unit is configured to convert the detection value into two physical quantities, an amplitude component indicating the amplitude of the detection value and a phase difference component indicating a phase difference of the detection value with respect to a reference phase of a predetermined frequency, and thereby output the detection signal from which the predetermined frequency component has been extracted.

14. the detection signal generator is configured to output the detection signal including a preliminary detection signal indicating one physical quantity including at least one of an effective value, an average value, and a peak value of the detection value; 4. The power conversion device for a resonant circuit according to claim 3, wherein the tracking control unit is configured to output the tracking signal based on the preliminary detection signal that is different from the detection signal of the vibration suppression unit and a preliminary output command that is the output command corresponding to the preliminary detection signal.

15. a step of outputting, as detection signals, a plurality of physical quantities calculated from a detected value of at least one of a current and a voltage in an output target including a resonant circuit to which AC power is output; generating a control signal for controlling both the amplitude and phase of the voltage or current in the AC power output to the resonant circuit based on the detection signal including a plurality of physical quantities and an output command corresponding to the plurality of physical quantities of the detection signal.

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