JP7062524B2 - Inverter device, gradient magnetic field power supply, and magnetic resonance imaging device - Google Patents

Description

Embodiments of the present invention relate to an inverter device, a gradient magnetic field power supply, and a magnetic resonance imaging device.

Conventionally, in an inverter device that requires a large current output, a current is secured by connecting a plurality of power devices used for controlling the output current in parallel. In such an inverter device, even if it is used within the original rating, if the cooling is biased among the power devices, the power device may be damaged due to the bias of heat generation. Similarly, even if there is no bias in cooling, the power device may be damaged due to the bias in heat generation caused by the difference in characteristics of the power devices connected in parallel. When the power device is damaged due to the uneven heat generation between the power devices, the operation of the inverter device may become unstable or the device may be damaged.

Japanese Unexamined Patent Publication No. 2008-228765 Japanese Unexamined Patent Publication No. 2013-118969 Japanese Unexamined Patent Publication No. 2010-104770 Japanese Unexamined Patent Publication No. 2007-259672 Japanese Unexamined Patent Publication No. 9-129794

The problem to be solved by the present invention is to stably operate the inverter device and reduce the risk of device damage.

The inverter device according to the embodiment includes a plurality of power devices connected in parallel and a control unit. The control unit controls the flow rate of the refrigerant that cools each power device so as to suppress the bias of heat generation between the power devices.

FIG. 1 is a diagram showing a configuration example of the magnetic resonance imaging apparatus according to the first embodiment. FIG. 2 is a diagram showing a configuration example of a gradient magnetic field power supply according to the first embodiment. FIG. 3 is a diagram showing a configuration example of the inverter device according to the first embodiment. FIG. 4 is a flowchart showing a processing procedure of cooling control performed by the control function according to the first embodiment. FIG. 5 is a flowchart showing a processing procedure of the state update processing of W1 and W2 shown in step S113 of FIG. FIG. 6 is a flowchart showing a processing procedure of the valve balance processing shown in steps S107 and S112 of FIG. FIG. 7 is a diagram for explaining the prediction of the ultimate temperature performed by the control function according to the third embodiment.

Hereinafter, embodiments of the inverter device, the gradient magnetic field power supply, and the magnetic resonance imaging device will be described in detail with reference to the drawings. Hereinafter, an example in which the inverter device according to the present application is applied to a gradient magnetic field power supply of a magnetic resonance imaging device will be described.

(First Embodiment)
FIG. 1 is a diagram showing a configuration example of a magnetic resonance imaging (MRI) apparatus according to a first embodiment.

For example, as shown in FIG. 1, the MRI apparatus 100 according to the present embodiment has a static magnetic field magnet 1, a gradient magnetic field coil 2, a gradient magnetic field power supply 3, a whole body coil 4, a local coil 5, a sleeper 6, and a transmission circuit 7. , The receiving circuit 8, the gantry 9, the interface 10, the display 11, the storage circuit 12, and the processing circuits 13 to 16.

The static magnetic field magnet 1 generates a static magnetic field in the imaging space in which the subject S is arranged. Specifically, the static magnetic field magnet 1 is formed in a hollow substantially cylindrical shape (including a magnet having an elliptical cross section orthogonal to the central axis) in an imaging space arranged on the inner peripheral side. Generates a static magnetic field. For example, the static magnetic field magnet 1 has a cooling container formed in a substantially cylindrical shape, and a magnet such as a superconducting magnet immersed in a cooling material (for example, liquid helium or the like) filled in the cooling container. The static magnetic field magnet 1 may be a magnet that generates a static magnetic field by using, for example, a permanent magnet.

The gradient magnetic field coil 2 generates a gradient magnetic field in the imaging space in which the subject S is arranged. Specifically, the gradient magnetic field coil 2 is formed in a hollow substantially cylindrical shape (including an elliptical shape of a cross section orthogonal to the central axis), and the current supplied from the gradient magnetic field power supply 3 is used. Based on this, a gradient magnetic field is generated in the imaging space arranged on the inner peripheral side. Further, the gradient magnetic field coil 2 has an X coil, a Y coil, and a Z coil corresponding to the X-axis, the Y-axis, and the Z-axis, respectively, and corresponds to the current supplied from the gradient magnetic field power supply 3 to each coil. Therefore, a gradient magnetic field along each of the X-axis, Y-axis, and Z-axis directions orthogonal to each other is generated in the imaging space.

Here, the X-axis, the Y-axis, and the Z-axis form a device coordinate system unique to the MRI device 100. For example, the X-axis is set along the horizontal direction, the Y-axis is set along the vertical direction, the Z-axis coincides with the axial direction of the gradient magnetic flux coil 2, and is generated by the static magnetic field magnet 1. It is set to follow the magnetic flux of the static magnetic field.

The gradient magnetic field power supply 3 supplies a current to each of the X coil, the Y coil, and the Z coil of the gradient magnetic field coil 2, so that the gradient magnetic field is along the X-axis, Y-axis, and Z-axis directions. Is generated in the imaging space. In this way, the gradient magnetic field power supply 3 appropriately supplies current to each of the X coil, the Y coil, and the Z coil, so that the gradient magnetic field is provided along the lead-out direction, the phase encoding direction, and the slice direction, which are orthogonal to each other. Can be generated.

Here, the axis along the lead-out direction, the axis along the phase encoding direction, and the axis along the slice direction constitute a logical coordinate system for defining a slice region or a volume region to be imaged. Specifically, the gradient magnetic fields along the lead-out direction, the phase encoding direction, and the slice gradient magnetic field are superimposed on the static magnetic field generated by the static magnetic field magnet 1, so that the MR signal generated from the subject S is generated. Gives spatial position information. The gradient magnetic field in the lead-out direction changes the frequency of the MR signal according to the position in the lead-out direction, thereby imparting position information along the lead-out direction to the MR signal. The phase-encoded gradient magnetic field changes the phase of the MR signal along the phase-encoded direction to impart position information along the phase-encoded direction to the MR signal. The slice gradient magnetic field imparts position information along the slice direction to the MR signal. For example, the slice gradient magnetic field is used to determine the direction, thickness, and number of slice regions when the imaging region is the slice region, and depends on the position in the slice direction when the imaging region is the volume region. It is used to change the phase of the MR signal.

The whole body coil 4 is an RF coil that applies an RF magnetic field to the imaging space in which the subject S is arranged and receives an MR signal generated from the subject S due to the influence of the RF magnetic field. Specifically, the whole-body coil 4 is formed in a hollow substantially cylindrical shape (including a coil having an elliptical cross section orthogonal to the central axis), and is an RF pulse signal supplied from the transmission circuit 7. Based on the above, an RF magnetic field is applied to the imaging space arranged on the inner peripheral side. Further, the whole body coil 4 receives the MR signal generated from the subject S due to the influence of the RF magnetic field, and outputs the received MR signal to the receiving circuit 8. For example, the whole body coil 4 is a QD (quadrature) coil.

The local coil 5 is an RF coil that receives the MR signal generated from the subject S. Specifically, the local coil 5 is an RF coil prepared for each part of the subject S, and is arranged in the vicinity of the part to be imaged when the subject S is imaged. Then, the local coil 5 receives the MR signal generated from the subject S due to the influence of the RF magnetic field applied by the whole body coil 4, and outputs the received MR signal to the receiving circuit 8. The local coil 5 may further have a function of a transmission coil that applies an RF magnetic field to the subject S. In that case, the local coil 5 is connected to the transmission circuit 7 and applies an RF magnetic field to the subject S based on the RF pulse signal supplied from the transmission circuit 7. For example, the local coil 5 is a surface coil or an array coil composed of a plurality of surface coils.

The sleeper 6 includes a top plate 6a on which the subject S is placed, and when the subject S is imaged, the top plate 6a on which the subject S is placed is moved to the imaging space. For example, the sleeper 6 is installed so that the longitudinal direction of the top plate 6a is in equilibrium with the central axis of the static magnetic field magnet 1.

The transmission circuit 7 outputs an RF pulse signal corresponding to the Larmor frequency peculiar to the target nucleus placed in the static magnetic field to the whole body coil 4. Specifically, the transmission circuit 7 has a pulse generator, an RF generator, a modulator, and an amplifier. The pulse generator produces a waveform of the RF pulse signal. The RF generator produces an RF signal with a resonant frequency. The modulator generates an RF pulse signal by modulating the amplitude of the RF signal generated by the RF generator with the waveform generated by the pulse generator. The amplifier amplifies the RF pulse signal generated by the modulator and outputs it to the whole body coil 4.

The receiving circuit 8 generates MR signal data based on the MR signal received by the whole body coil 4 and the local coil 5, and outputs the generated MR signal data to the processing circuit 14. Specifically, the receiving circuit 8 has a detector, and the MR signal data is obtained by subtracting the resonance frequency component from the MR signal received by the whole body coil 4 and the local coil 5 by the detector. Is generated, and the generated MR signal data is output to the processing circuit 14.

The gantry 9 has a hollow bore 9a formed in a substantially cylindrical shape (including an elliptical cross section orthogonal to the central axis), and has a static magnetic field magnet 1, a gradient magnetic field coil 2, and a whole body. It supports the coil 4. Specifically, in the gantry 9, the gradient magnetic field coil 2 is arranged on the inner peripheral side of the static magnetic field magnet 1, the whole body coil 4 is arranged on the inner peripheral side of the gradient magnetic field coil 2, and the inner circumference of the whole body coil 4 is arranged. With the bore 9a arranged on the side, the static magnetic field magnet 1, the gradient magnetic field coil 2, and the whole body coil 4 are supported. Here, the space in the bore 9a of the gantry 9 becomes an imaging space in which the subject S is arranged when the subject S is imaged.

Here, an example will be described in which the MRI apparatus 100 has a so-called tunnel type configuration in which the static magnetic field magnet 1, the gradient magnetic field coil 2, and the whole body coil 4 are each formed in a substantially cylindrical shape. The form is not limited to this. For example, the MRI apparatus 100 has a so-called open type configuration in which a pair of static magnetic field magnets, a pair of gradient magnetic field coils, and a pair of RF coils are arranged so as to face each other across an imaging space in which the subject S is arranged. You may be doing it. In this case, the space sandwiched by the pair of static magnetic field magnets, the pair of gradient magnetic field coils and the pair of RF coils corresponds to the bore in the tunnel type configuration.

The interface 10 receives various instructions and input operations of various information from the operator. Specifically, the interface 10 is connected to the processing circuit 16, converts an input operation received from the operator into an electric signal, and outputs the input operation to the processing circuit 16. For example, the interface 10 includes a trackball for setting imaging conditions and a region of interest (ROI), a switch button, a mouse, a keyboard, a touch pad for performing input operations by touching an operation surface, and a display screen. It is realized by a touch screen in which a mouse and a touch pad are integrated, a non-contact input circuit using an optical sensor, a voice input circuit, and the like. In the present specification, the interface 10 is not limited to the one provided with physical operating parts such as a mouse and a keyboard. For example, an example of the interface 10 includes an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the device and outputs the electric signal to a control circuit.

The display 11 displays various information and various images. Specifically, the display 11 is connected to the processing circuit 16 and converts various information and various image data sent from the processing circuit 16 into electrical signals for display and outputs the data. For example, the display 11 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, a touch panel, or the like.

The storage circuit 12 stores various data. Specifically, the storage circuit 12 stores MR signal data and image data. For example, the storage circuit 12 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, an optical disk, or the like.

The processing circuit 13 has a sleeper control function 13a. The sleeper control function 13a controls the operation of the sleeper 6 by outputting an electric signal for control to the sleeper 6. For example, the sleeper control function 13a receives an instruction from the operator to move the top plate 6a in the longitudinal direction, the vertical direction, or the left-right direction via the interface 10, and moves the sleeper 6a according to the received instruction. The moving mechanism of the top plate 6a included in 6 is operated.

The processing circuit 14 has a data acquisition function 14a. The data collection function 14a collects MR signal data of the subject S by executing various pulse sequences. Specifically, the data acquisition function 14a executes a pulse sequence by driving the gradient magnetic field power supply 3, the transmission circuit 7, and the reception circuit 8 according to the sequence execution data output from the processing circuit 16. Here, the sequence execution data is data representing a pulse sequence, the timing at which the gradient magnetic field power supply 3 supplies a current to the gradient magnetic field coil 2, the strength of the supplied current, and the transmission circuit 7 supplying the whole body coil 4. This is information that defines the strength and supply timing of the RF pulse signal, the detection timing at which the receiving circuit 8 detects the MR signal, and the like. Then, the data collection function 14a receives the MR signal data from the reception circuit 8 as a result of executing the pulse sequence, and stores the received MR signal data in the storage circuit 12. Here, the set of MR signal data received by the data acquisition function 14a is arranged two-dimensionally or three-dimensionally according to the position information given by the lead-out gradient magnetic field, the phase-encoded gradient magnetic field, and the slice gradient magnetic field described above. By doing so, it is stored in the storage circuit 12 as data constituting the k space.

The processing circuit 15 has an image generation function 15a. The image generation function 15a generates an image based on the MR signal data stored in the storage circuit 12. Specifically, the image generation function 15a reads out the MR signal data stored in the storage circuit 12 by the data acquisition function 14a, and performs post-processing, that is, reconstruction processing such as Fourier transform on the read MR signal data. Generate an image with. Further, the image generation function 15a stores the image data of the generated image in the storage circuit 12.

The processing circuit 16 has a main control function 16a. The main control function 16a controls the entire MRI apparatus 100 by controlling each component of the MRI apparatus 100. Specifically, the main control function 16a displays a GUI (Graphical User Interface) for receiving various instructions and input operations of various information from the operator on the display 11. Then, the main control function 16a controls each component of the MRI apparatus 100 according to the input operation received via the interface 10. For example, the main control function 16a receives input of imaging conditions from the operator via the interface 10. Then, the main control function 16a generates sequence execution data based on the received imaging conditions, and transmits the sequence execution data to the processing circuit 14 to execute various pulse sequences. Further, for example, the main control function 16a reads image data from the storage circuit 12 and outputs the image data to the display 11 in response to a request from the operator.

Here, the processing circuits 13 to 16 described above are realized by, for example, a processor. In this case, the processing function of each processing circuit is stored in the storage circuit 12 in the form of a program that can be executed by a computer, for example. Each processing circuit realizes a function corresponding to each program by reading each program from the storage circuit 12 and executing the program. Here, each processing circuit may be configured by a plurality of processors, and each processing function may be realized by each processor executing a program. Further, the processing functions of each processing circuit may be appropriately distributed or integrated into a single processing circuit or a plurality of processing circuits. Further, here, a single storage circuit 12 has been described as storing a program corresponding to each processing function, but a plurality of storage circuits are distributed and arranged so that the processing circuits correspond from individual storage circuits. It may be configured to read the program.

Under such a configuration, in the MRI apparatus 100 according to the present embodiment, the gradient magnetic field power supply 3 responds to the waveform of the gradient magnetic field applied to the imaging space based on the input signal transmitted from the processing circuit 14. The voltage is output to the gradient magnetic field coil 2. Here, the input signal is a signal representing the waveform of the gradient magnetic field generated in the gradient magnetic field coil 2, and is a signal simulating the waveform of the gradient magnetic field applied when the pulse sequence is executed.

FIG. 2 is a diagram showing a configuration example of the gradient magnetic field power supply 3 according to the first embodiment.

For example, as shown in FIG. 2, the gradient magnetic field power supply 3 according to the present embodiment includes a power supply device 3a and an inverter device 20.

The power supply device 3a supplies DC power to the inverter device 20 based on the power supplied from a part of the MRI device 100 or a power supply facility (not shown) provided separately from the MRI device 100.

The inverter device 20 includes a plurality of power devices connected in parallel, and uses a gradient magnetic field coil to apply a voltage according to the waveform of the gradient magnetic field applied to the imaging space based on the DC power supplied from the power supply device 3a. Output to 2.

For example, the inverter device 20 includes a first power device 21a, a second power device 21b, a third power device 21c, a fourth power device 21d, a fifth power device 21e, and a sixth. It includes a power device 21f, a seventh power device 21g, an eighth power device 21h, an electrolytic capacitor 22, a current sensor 23, and a processing circuit 24.

Here, each power device is a switching element and has a transistor, a diode, and the like. For example, the transistor is an IGBT (Insulated Gate Bipolar Transistor). The diode is an FWD (Free Wheeling Diode).

The first power device 21a and the second power device 21b, the third power device 21c and the fourth power device 21d, the fifth power device 21e and the sixth power device 21f, the seventh power device 21g and the seventh. The power devices 21h of 8 are connected in parallel, respectively. Further, the first power device 21a and the third power device 21c, the second power device 21b and the fourth power device 21d, the fifth power device 21e and the seventh power device 21g, and the sixth power device 21f. And the eighth power device 21h are connected in series, respectively.

The first power device 21a, the second power device 21b, the fifth power device 21e, and the sixth power device 21f are each connected to the positive terminal of the power supply device 3a. Further, the third power device 21c, the fourth power device 21d, the seventh power device 21g, and the eighth power device 21h are each connected to the negative terminal of the power supply device 3a. Further, the path between the first power device 21a and the third power device 21c is connected to the path between the second power device 21b and the fourth power device 21d. Further, the path between the fifth power device 21e and the seventh power device 21g is connected to the path between the sixth power device 21f and the eighth power device 21h. Further, a terminal on the negative side of the gradient magnetic field coil 2 is connected to the path between the first power device 21a and the third power device 21c. Further, a terminal on the positive side of the gradient magnetic field coil 2 is connected to the path between the sixth power device 21f and the eighth power device 21h.

As a result, the first power device 21a, the second power device 21b, the third power device 21c, the fourth power device 21d, the fifth power device 21e, the sixth power device 21f, and the seventh power device The 21g and the eighth power device 21h constitute a full bridge circuit, and output a pulse voltage to the gradient magnetic field coil 2 based on the DC power supplied from the power supply device 3a.

Specifically, the first power device 21a is the upper arm of the first leg of the first stage in the full bridge circuit, and the third power device 21c is the upper arm of the first leg of the first stage. It is a lower arm. Further, the second power device 21b is the upper arm of the first leg of the second stage, and the fourth power device 21d is the lower arm of the first leg of the second stage. Further, the fifth power device 21e is the upper arm of the second leg of the first stage, and the seventh power device 21g is the lower arm of the second leg of the first stage. Further, the sixth power device 21f is the upper arm of the second leg of the second stage, and the eighth power device 21h is the lower arm of the second leg of the second stage.

According to such a configuration, the first power device 21a, the second power device 21b, the seventh power device 21g, and the eighth power device 21h are turned off, respectively, and the third power device 21c and the fourth power device 21c are turned off. When the power device 21d, the fifth power device 21e, and the sixth power device 21f are turned on, a current flows in the gradient magnetic field coil 2 in the forward direction. On the other hand, the first power device 21a, the second power device 21b, the seventh power device 21g, and the eighth power device 21h are turned on, respectively, and the third power device 21c, the fourth power device 21d, and the eighth power device 21d are turned on. When the power device 21e of 5 and the power device 21f of the sixth are turned off, a current flows in the gradient magnetic field coil 2 in the opposite direction. Then, by alternately switching between these two states, a pulse voltage having an arbitrary pulse width can be continuously output.

Here, an example in which the number of stages of the full bridge circuit in the inverter device 20 is two stages will be described, but the number of stages of the full bridge circuit is not limited to this, and may be one stage or three stages. It may be the above.

The electrolytic capacitor 22 includes a power supply device 3a, a first power device 21a, a second power device 21b, a third power device 21c, a fourth power device 21d, a fifth power device 21e, and a sixth power device. It is arranged between the 21f, the seventh power device 21g, and the eighth power device 21h, and smoothes the current supplied from the power supply device 3a to each power device.

The current sensor 23 detects the current flowing through the output end of the inverter device 20, and transmits a feedback signal indicating the magnitude of the detected current to the processing circuit 24.

The processing circuit 24 drives each power device based on the input signal transmitted from the processing circuit 14, and outputs a pulse voltage corresponding to the waveform of the gradient magnetic field applied to the imaging space to the gradient magnetic field coil 2. ..

Specifically, the processing circuit 24 receives an input signal transmitted from the processing circuit 14 and a feedback signal transmitted from the current sensor 23, and receives an error signal which is a difference between the received input signal and the feedback signal. Generate. Then, the processing circuit 24 PWM (Pulse Width Modulation) modulates the generated error signal and drives each power device based on the PWM-modulated signal to obtain a pulse voltage according to the magnitude of the error signal. generate.

Here, the processing circuit 24 turns off the first power device 21a, the second power device 21b, the seventh power device 21g, and the eighth power device 21h, respectively, and turns off the third power device 21c and the fourth power device 21c, respectively. The power device 21d, the fifth power device 21e, and the sixth power device 21f are turned on, respectively, and the first power device 21a, the second power device 21b, the seventh power device 21g, and the sixth power device 21f. 8 power devices 21h are turned on, and the third power device 21c, the fourth power device 21d, the fifth power device 21e, and the sixth power device 21f are turned off alternately. In addition, by driving each power device, a pulse voltage corresponding to the magnitude of the error signal is generated.

That is, the processing circuit 24 has a gradient magnetic field coil from each power device so that a current matching the input signal transmitted from the processing circuit 14 flows through the gradient magnetic field coil 2 based on the feedback signal transmitted from the current sensor 23. The pulse voltage output to 2 is controlled.

Here, in an inverter device such as the above-mentioned inverter device 20 in which a plurality of power devices are connected in parallel and mounted, a bias in cooling occurs among the power devices even if the power devices are used within the original rating. In addition, the power device may be damaged due to the bias of heat generation. Similarly, even if there is no bias in cooling, there are differences in the characteristics of power devices connected in parallel (including differences in characteristics that occur from the initial state due to manufacturing errors, characteristics that occur later due to deterioration over time, etc.). The bias of heat generation caused by the above may cause damage to the power device. When the power device is damaged due to the uneven heat generation between the power devices, the operation of the inverter device 20 may become unstable or the device may be damaged.

Therefore, the inverter device 20 according to the present embodiment is configured so that the inverter device can be stably operated and the risk of device damage can be reduced by suppressing the bias of heat generation between the power devices. ing.

Specifically, the inverter device 20 includes a control unit that controls the flow rate of the refrigerant that cools each power device so as to suppress the bias of heat generation between the power devices.

Here, in the present embodiment, the inverter device 20 is equipped with a plurality of power devices and includes a cooling plate having a plurality of flow paths provided for each power device. Then, the control unit controls the flow rate of the refrigerant flowing in each of the plurality of flow paths provided in the cooling plate.

Further, in the present embodiment, the inverter device 20 is provided for each flow path of the cooling plate, and includes a solenoid valve having a plurality of valves for circulating the refrigerant in each flow path. Then, the control unit controls the flow rate of the refrigerant by controlling each valve of the solenoid valve.

Further, in the present embodiment, the inverter device 20 further includes a monitoring unit for monitoring the temperature of each power device. Then, the control unit controls the flow rate of the refrigerant based on the temperature monitored by the monitoring unit.

Hereinafter, the inverter device 20 having such a configuration will be described in detail. In this embodiment, an example in which cooling water is used as the refrigerant will be described. Further, in the present embodiment, an example in which a water cooling plate is used as the cooling plate will be described.

FIG. 3 is a diagram showing a configuration example of the inverter device 20 according to the first embodiment.

Here, the cooling control performed between the first power device 21a and the second power device 21b will be described as an example, but the third power device 21c and the fourth power device 21d will be described. Meanwhile, similar cooling control is performed between the fifth power device 21e and the sixth power device 21f, and between the seventh power device 21g and the eighth power device 21h.

For example, as shown in FIG. 3, the inverter device 20 according to the present embodiment includes a water cooling plate 25 and a solenoid valve 26.

The water cooling plate 25 is equipped with a first power device 21a and a second power device 21b, and has a first flow path 25a and a second flow path 25b through which cooling water flows. Here, the first flow path 25a is provided at a position where the first power device 21a is arranged, and the second flow path 25b is provided at a position where the second power device 21b is arranged. ing.

The solenoid valve 26 has a first valve 26a that allows cooling water to flow through the first flow path 25a of the water cooling plate 25, and a second valve 26b that allows cooling water to flow through the second flow path 25b.

Here, one end of the first flow path 25a of the water cooling plate 25 is connected to the inflow pipe 27a via the first valve 26a of the solenoid valve 26, and the other end is connected to the outflow pipe 27b. There is. Further, one end of the second flow path 25b of the water cooling plate 25 is connected to the inflow pipe 27a via the second valve 26b of the solenoid valve 26, and the other end is connected to the outflow pipe 27b. ..

Then, the solenoid valve 26 uses the first valve 26a and the cooling water supplied from a part of the MRI device 100 or a cooling device provided separately from the MRI device 100 (not shown) via the inflow pipe 27a. Allocate to each of the second valves 26b. Then, the cooling water flowing through the first flow path 25a and the second flow path 25b of the water cooling plate 25 via the first valve 26a and the second valve 26b of the solenoid valve 26 passes through the outflow pipe 27b. It is returned to the cooling device via.

As described above, in the inverter device 20 according to the present embodiment, the cooling water is circulated through the first flow path 25a and the second flow path 25b of the water cooling plate 25, respectively, so that the first power device 21a and the second flow path 25a are circulated. It is configured so that the power device 21b and the power device 21b can be individually cooled.

Further, in the present embodiment, the processing circuit 24 has a monitoring function 24a and a control function 24b. Here, the monitoring function 24a is an example of a monitoring unit. Further, the control function 24b is an example of a control unit.

The monitoring function 24a detects the temperature of the first power device 21a via the first temperature sensor 28a provided in the first power device 21a. Further, the monitoring function 24a detects the temperature of the second power device 21b via the second temperature sensor 28b provided in the second power device 21b.

The control function 24b controls the flow rate of the cooling water that cools each power device so as to suppress the bias of heat generation between the first power device 21a and the second power device 21b. Specifically, the control function 24b controls each valve of the solenoid valve 26 based on the temperature of each power device detected by the monitoring function 24a, so that the cooling water circulates in each flow path of the water cooling plate 25. Control the flow rate of.

In the present embodiment, the control function 24b dynamically controls the flow rate of the cooling water for cooling each power device during the operation of the inverter device 20 as described below.

In the following description, the temperature of the first power device 21a is T1, the temperature of the second power device 21b is T2, the flow rate of the cooling water for cooling the first power device 21a is W1, and the second power device. Let W2 be the flow rate of the cooling water for cooling 21b, and W _TOTAL be the total flow rate of the cooling water that can be supplied from the cooling device.

FIG. 4 is a flowchart showing a processing procedure of cooling control performed by the control function 24b according to the first embodiment.

For example, as shown in FIG. 4, the control function 24b calculates the difference ΔT between T1 and T2 detected by the monitoring function 24a (step S101).

When the absolute value of ΔT is equal to or less than the preset threshold value ΔT _TH (step S102, lower), the control function 24b generates heat between the first power device 21a and the second power device 21b. It is considered that the bias of is within the permissible range, and after the state update processing of W1 and W2 described later is performed (step S113), the process returns to the processing of step S101.

On the other hand, when the absolute value of ΔT is larger than ΔT _TH , the control function 24b considers that the heat generation bias between the first power device 21a and the second power device 21b is out of the permissible range. Execute the following processing.

First, when ΔT is larger than ΔT _TH (step S102, left), the control function 24b considers that T1 exceeds the allowable range and is higher than T2, and determines whether W1 is adjustable or not. Determination (step S103). Here, the control function 24b determines that W1 can be adjusted when W1 is within the adjustment range based on the adjustment range of W1 set at that time, and W1 is out of the adjustment range. If, it is determined that W1 is not adjustable.

Then, when it is determined that W1 is adjustable (step S103, Yes), the control function 24b increases W1 by a preset ΔW1 and increases W _TOTAL by ΔW1 (step S104). .. As a result, the cooling of the first power device 21a is strengthened by the amount of increasing W1, and as a result, the temperature of the first power device 21a is lowered to approach the temperature of the second power device 21b. Become.

Further, when it is determined that W1 is not adjustable (step S103, No), the control function 24b determines whether or not W2 is adjustable (step S105). Here, the control function 24b determines that W2 can be adjusted when W2 is within the adjustment range based on the adjustment range of W2 set at that time, and W2 is out of the adjustment range. If, it is determined that W2 is not adjustable.

Then, when it is determined that W2 is adjustable (step S105, Yes), the control function 24b reduces W2 by a preset ΔW2 and reduces W _TOTAL by ΔW2 (step S106). .. As a result, the cooling of the second power device 21b is weakened by the amount that W2 is reduced, and as a result, the temperature of the second power device 21b rises and approaches the temperature of the first power device 21a in parallel. It will act to balance the loss of the connected power device.

As described above, when the control function 24b considers that T1 exceeds the allowable range and is higher than T2, the control function 24b enhances the cooling of the first power device 21a to increase the temperature of the first power device 21a. To bring the temperature of the second power device 21b closer to the temperature of the second power device 21b, or to weaken the cooling of the second power device 21b to raise the temperature of the second power device 21b to bring the temperature of the second power device 21b closer to that of the first power device 21a. Get closer to the temperature. As a result, the bias of heat generation between the first power device 21a and the second power device 21b is suppressed.

In this way, after increasing W1 or decreasing W2, the control function 24b performs a valve balance process described later (step S107), and further performs a state update process of W1 and W2 described later (step S107). Step S113) returns to the process of step S101.

If it is determined that neither W1 nor W2 can be adjusted (steps S105, No), the control function 24b is a processing circuit so as to output a warning to the display 11 or the like that W _TOTAL is insufficient. After instructing the main control function 16a of 16 and degenerating the output of each power device (step S114), the process returns to the process of step S101.

On the other hand, when ΔT is smaller than −ΔT _TH (step S102, right), the control function 24b considers that T2 is higher than T1 beyond the permissible range, and W2 can be adjusted. (Step S108). Here, the control function 24b determines that W2 can be adjusted when W2 is within the adjustment range based on the adjustment range of W2 set at that time, and W2 is out of the adjustment range. If, it is determined that W2 is not adjustable.

Then, when it is determined that W2 is adjustable (step S108, Yes), the control function 24b increases W2 by a preset ΔW2 and increases W _TOTAL by ΔW2 (step S109). .. As a result, the cooling of the second power device 21b is strengthened by the amount of increasing W2, and as a result, the temperature of the second power device 21b is lowered to approach the temperature of the first power device 21a. Become.

If it is determined that W2 is not adjustable (steps S108, No), the control function 24b determines whether or not W1 is adjustable (step S110). Here, the control function 24b determines that W1 can be adjusted when W1 is within the adjustment range based on the adjustment range of W1 set at that time, and W1 is out of the adjustment range. If, it is determined that W1 is not adjustable.

Then, when it is determined that W1 is adjustable (step S110, Yes), the control function 24b reduces W1 by a preset ΔW1 and reduces W _TOTAL by ΔW1 (step S111). .. As a result, the cooling of the first power device 21a is weakened by the amount that W1 is reduced, and as a result, the temperature of the first power device 21a rises and approaches the temperature of the second power device 21b in parallel. It will act to balance the loss of the connected power device.

As described above, when the control function 24b considers that T2 is higher than T1 beyond the permissible range, the temperature of the second power device 21b is increased by strengthening the cooling of the second power device 21b. To bring the temperature of the first power device 21a closer to the temperature of the first power device 21a, or to weaken the cooling of the first power device 21a to raise the temperature of the first power device 21a to bring the temperature of the first power device 21a closer to that of the second power device 21b. Get closer to the temperature. As a result, the bias of heat generation between the first power device 21a and the second power device 21b is suppressed.

In this way, after increasing W2 or decreasing W1, the control function 24b performs a valve balance process described later (step S112), and further performs a state update process of W1 and W2 described later (step S112). Step S113) returns to the process of step S101.

If it is determined that neither W2 nor W1 can be adjusted (steps S110, No), the control function 24b outputs a warning to the display 11 or the like that W _TOTAL is insufficient. After instructing the main control function 16a of the above and degenerating the output of each power device (step S114), the process returns to the process of step S101.

FIG. 5 is a flowchart showing a processing procedure of the state update processing of W1 and W2 shown in step S113 of FIG.

For example, as shown in FIG. 5, the control function 24b compares the previous W _TOTAL with the current W _TOTAL (step S201).

Then, when the current W _TOTAL is larger than the previous W _TOTAL (step S201, Yes), the control function 24b expands the adjustment range of W1 and W2 by a preset size, and requests to that effect. It is transmitted to the processing circuit 16 (step S202).

In the processing circuit 16 that received this request, the main control function 16a, and in the processing circuit 16 that received this request, the main control function 16a increases W _TOTAL by the amount that the adjustment range of W1 and W2 is expanded. Control the cooling system. This loosens the W _TOTAL law.

At this time, the main control function 16a determines whether or not the request is possible based on, for example, the situation of the entire MRI apparatus 100. For example, when the W _TOTAL exceeds a preset upper limit value as a result of increasing the W _TOTAL , the main control function 16a continues the operation of the inverter device 200 according to the situation of the entire MRI device 100. Is possible or not. Then, when it is determined that the operation of the inverter device 200 can be continued, the main control function 16a controls the cooling device so as to increase the W _TOTAL while updating the upper limit value of the W _TOTAL . .. If it is determined that the operation of the inverter device 200 cannot be continued, the main control function 16a stops the operation of the inverter device 20.

On the other hand, when the current W _TOTAL is smaller than the previous W _TOTAL (step S201, No, step S203, Yes), the control function 24b reduces the adjustment range of W1 and W2 by a preset size. A permission to that effect is transmitted to the main control function 16a of the processing circuit 16 (step S204). Upon receiving this permission, the main control function 16a controls the cooling device so as to lower the W _TOTAL by the amount that the adjustment range of W1 and W2 is reduced. As a result, the flow rate of the cooling water used for cooling can be suppressed, which can contribute to energy saving.

If the previous W _TOTAL is equal to the current W _TOTAL (steps S201, No, step S203, No), the control function 24b does not control W _TOTAL and processes W1 and W2 for updating the status. To finish.

In this way, by dynamically controlling W _TOTAL , it is possible to efficiently cool the power device and also contribute to energy saving.

FIG. 6 is a flowchart showing a processing procedure of the valve balance processing shown in steps S107 and S112 of FIG.

For example, as shown in FIG. 6, the control function 24b determines whether the valve balance or the total flow rate is the rule of the adjustment range of W1 and W2 (step S301). Here, the control function 24b determines that the total flow rate is a rule when the current W _TOTAL is equal to or higher than the preset flow rate default value. Further, the control function 24b determines that when the current W _TOTAL is less than the default flow rate value, W1 exceeds a preset range and is larger than W2, or W2 exceeds a preset range. When it is larger than W1, it is considered that the balance of W1 and W2 is out of balance, and it is determined that the valve balance is a rule.

Then, when it is determined that the valve balance is a rule (step S301, bottom), the control function 24b has an absolute value of a value obtained by subtracting a preset valve reference value from W1 and a value obtained in advance from W2. Compare with the absolute value of the value obtained by subtracting the set valve reference value (step S302).

Here, when the absolute value of the value obtained by subtracting the valve reference value from W1 is larger than the absolute value of the value obtained by subtracting the valve reference value from W2 (step S302, Yes), in the control function 24b, W1 is the valve reference. The first valve 26a and the second valve 26b are balanced (step S303) so as to approach the value. As a result, the control function 24b can bring W1 closer to the valve reference value while maintaining the ratio of the operation amount of each valve.

On the other hand, when the absolute value of the value obtained by subtracting the valve reference value from W1 is equal to or less than the absolute value of the value obtained by subtracting the valve reference value from W2 (steps S302, No), W2 is the valve reference in the control function 24b. The first valve 26a and the second valve 26b are balanced to approach the value (step S304). As a result, the control function 24b can bring W2 closer to the valve reference value while maintaining the ratio of the operation amount of each valve.

When it is determined that the total flow rate is a rule (step S301, right), the control function 24b ends the valve balance processing without performing the equilibrium operation of each valve.

In this way, by bringing W1 and W2 closer to the valve reference value while maintaining the ratio of the operating amount of each valve, the flow rate ratio of W1 and W2 can be stabilized when W _TOTAL is sufficient. On the other hand, when W _TOTAL is not sufficient, that is, when the total flow rate is a rule, the adjustment range of W1 and W2 is expanded by the state update process of W1 and W2 shown in FIG. Is transmitted to the processing circuit 16, and the W _TOTAL rule is relaxed.

Although the monitoring function 24a and the control function 24b of the processing circuit 24 have been described above, the above-mentioned monitoring function 24a and the control function 24b are realized by, for example, independent electric circuits.

Alternatively, for example, the processing circuit 24 is realized by a processor. In this case, for example, the monitoring function 24a and the control function 24b of the processing circuit 24 are stored in a predetermined storage circuit in the form of a program that can be executed by a computer. Then, the processing circuit 24 realizes the processing function corresponding to the program by reading the program from the storage circuit and executing the program. In other words, the processing circuit 24 in the state where the program is read out has each processing function shown in the processing circuit 24 of FIG. In this case, the processing of each step shown in FIGS. 4 to 6 is realized, for example, by the processing circuit 24 reading a program corresponding to the control function 24b from a predetermined storage circuit and executing the processing.

Further, FIG. 3 shows an example in which the monitoring function 24a and the control function 24b are realized by a single processing circuit 24, but the embodiment is not limited to this. For example, a plurality of independent processors may be combined to form a processing circuit 24, and each processor may execute a program to realize each processing function. Further, each processing function of the processing circuit 24 may be appropriately distributed or integrated into a single or a plurality of processing circuits.

As described above, according to the first embodiment, the control function 24b determines the flow rate of the cooling water that cools each power device so as to suppress the bias of heat generation among the plurality of power devices connected in parallel. By controlling, the inverter device can be operated stably and the risk of device damage can be reduced.

Further, according to the first embodiment, the control function 24b dynamically controls the flow rate of the cooling water for cooling each power device during the operation of the inverter device 20, thereby during the operation of the inverter device 20. Even if heat generation bias occurs due to variations in the characteristics of each power device, heat generation can be equalized in real time.

As described above, in the first embodiment, the temperature of each power device connected in parallel is monitored, and the heat generation bias due to the cooling system and the power device characteristics is dynamically corrected, so that each power device is used. It becomes possible to prevent the damage of the inverter device 20 and to operate the inverter device 20 stably. Further, in the first embodiment, by controlling and optimally distributing the cooling water, it becomes possible to suppress the energy (resource use) necessary and sufficient for stable operation of the inverter device 20, and also to save energy. Can contribute.

It should be noted that the first embodiment described above can be implemented by appropriately modifying a part of the configuration of the inverter device 20. Therefore, in the following, some modifications according to the first embodiment will be described as the second to sixth embodiments. In the second to sixth embodiments described below, the points different from the first embodiment will be mainly described, and detailed description of the contents common to the first embodiment will be omitted.

(Second embodiment)
For example, in the first embodiment, an example in which the monitoring function 24a monitors the temperature of each power device has been described, but the embodiment is not limited to this.

For example, the monitoring function 24a may monitor the temperature of the measurement site that indirectly indicates the temperature of each power device, instead of monitoring the temperature of each power device. In this case, for example, the monitoring function 24a monitors the temperature of the cooling water flowing out from each flow path of the water cooling plate 25 provided for each power device as a measurement site that indirectly indicates the temperature of each power device. do. Alternatively, for example, the monitoring function 24a monitors the temperature of the location of each power device on the water cooling plate 25 as a measurement site that indirectly indicates the temperature of each power device.

Then, for example, the control function 24b uses the temperature of the measurement site instead of the temperature of the power device (T1, T2) in the first embodiment, so that the flow rate of the cooling water is the same as in the first embodiment. To control.

(Third embodiment)
Further, in the first embodiment, an example in which the control function 24b controls the flow rate of the cooling water based on the temperature of each power device has been described, but the embodiment is not limited to this.

For example, the control function 24b may predict the reached temperature from the change in the temperature of each power device in the transition state, and control the flow rate of the cooling water based on the reached temperature. In this case, for example, the control function 24b predicts the reached temperature based on the change in the temperature of each power device and the temperature time constant of each power device.

FIG. 7 is a diagram for explaining the prediction of the ultimate temperature performed by the control function 24b according to the third embodiment.

For example, as shown in FIG. 12, the temperature T of the power device gradually rises with the lapse of time t after starting the operation, and reaches the reached temperature T _a . Here, for example, the temperature time constant is defined as the time from the initial temperature to reaching 63% of the reached temperature _Ta .

From such characteristics, for example, the control function _24b predicts the ultimate temperature Ta from the speed of temperature rise dT / dt of each power device. Specifically, the control function 24b calculates the temperature rise speed dT / dt at each predetermined sampling interval, and calculates the temperature time constant from the slope of dT / dt. Then, the control function _24b predicts the reached temperature Ta from the change of dT / dt and the temperature time constant. Here, as a method for calculating the temperature time constant and _a method for predicting the ultimate temperature Ta, a known method can be used. If the temperature time constant of each power device is known, the calculation of the temperature time constant can be omitted.

After that, the control function 24b uses the predicted reached temperature Ta instead of the temperature of the power device (T1, _T2 ) in the first embodiment, so that the flow rate of the cooling water is the same as in the first embodiment. To control.

In this way, by predicting the ultimate temperature from the change in the temperature of each power device in the transient state and controlling the flow rate of the cooling water, it is possible to control the flow rate before the temperature reaches the steady state, and the temperature fluctuates. It becomes possible to improve the responsiveness of the cooling control to.

Also in the third embodiment, the temperature of the measurement site that indirectly indicates the temperature of each power device may be used instead of the temperature of each power device. In this case, according to the third embodiment, the temperature is monitored by predicting the reached temperature by adding the temperature time constant of each measurement site in addition to the speed of temperature rise in the transient state. The degree of freedom when setting the measurement site can be increased.

(Fourth Embodiment)
Further, in the first embodiment, an example in which each power device targeted for cooling control is a switching element has been described, but the embodiment is not limited to this.

For example, a plurality of power devices subject to cooling control may be of different types, such as transistors and diodes. In this case, the control function 24b controls the flow rate of the cooling water according to the cooling conditions required according to the operation of each power device. The cooling conditions referred to here are, for example, a temperature threshold value for determining whether or not the heat generation bias is within the allowable range, and appropriate conditions are set according to the specification of each power device. To.

As a result, even when different types of power devices are targeted for cooling, the cooling water for cooling each power device can be dynamically and optimally distributed.

(Fifth Embodiment)
Further, in the first embodiment, an example in which the control function 24b performs so-called feedback control in which the flow rate of the refrigerant is controlled based on the temperature of each power device has been described, but the embodiment is not limited to this. ..

For example, the control function 24b may perform feed-forward control of the flow rate of the cooling water by predicting the magnitude of heat generation generated in each power device based on the operation information of the inverter device 20. As the operation information referred to here, various information can be used as long as it is information that can be used for predicting heat generation of each power device.

For example, the control function 24b uses information indicating the waveform of the current output from the gradient magnetic field power supply 3 to the gradient magnetic field coil 2 as operation information. For example, the control function 24b uses sequence execution data representing a pulse sequence as operation information.

Specifically, the control function 24b calculates the gradient (di / dt) of the gradient magnetic field waveform generated in the gradient magnetic field coil 2 based on the input signal transmitted from the processing circuit 14, and the calculated magnitude of the gradient is large. The output voltage to the gradient magnetic field coil 2 is calculated from the width and direction. After that, the control function 24b calculates the current flowing through each power device from the output voltage according to the characteristics of each power device, and predicts the calorific value from the calculated current, so that each of the current flows when the current flows. Predict the temperature of power devices. Here, as a method for predicting the calorific value from the current, a known method can be used. Then, the control function 24b controls the flow rate of the cooling water as in the first embodiment by using the predicted temperature instead of the temperature of the power device (T1, T2) in the first embodiment. ..

In this way, by performing feedforward control of the flow rate of the cooling water using the operation information of the inverter device 20, it is possible to enhance the responsiveness of the cooling control to the fluctuation of the temperature.

(Sixth Embodiment)
Further, in the first embodiment described above, the monitoring function 24a monitors the temperature of each power device, and the control function 24b controls the flow rate of the cooling water based on the temperature of each power device. As described above, the embodiment is not limited to this.

For example, the monitoring function 24a may monitor the current flowing through each power device instead of monitoring the temperature of each power device. In this case, for example, the monitoring function 24a detects the current flowing through each power device via a current sensor provided at an input end or an output end of each power device.

Then, for example, the control function 24b calculates the loss from the waveform of the current monitored by the monitoring function 24a, predicts the temperature from the loss, and controls the flow rate of the cooling water based on the temperature. Here, a known method can be used as a method for predicting the loss from the waveform of the current. In this case, for example, the control function 24b uses the temperature predicted from the loss instead of the temperature of the power device (T1, T2) in the first embodiment, so that the control function 24b can be used in the same manner as in the first embodiment. Control the flow rate of cooling water.

In this way, by performing temperature prediction by calculating the loss from the waveform of the current instead of direct temperature monitoring, it becomes possible to further enhance the responsiveness of the cooling control to the temperature fluctuation.

Although the first to sixth embodiments have been described above, the above-described embodiments are not limited to the cases where they are implemented separately, and may be implemented in an appropriate combination.

For example, the control function 24b may perform both the feedback control and the feedforward control described above. In this way, by combining the feedback control of the flow rate of the cooling water and the feedforward control, it is possible to achieve both the followability and the responsiveness of the cooling control to the temperature fluctuation.

Further, in the above-described embodiment, an example in which cooling water is used as the refrigerant has been described, but the embodiment is not limited to this. For example, a liquid other than cooling water may be used as the refrigerant. Further, air may be used as the refrigerant. In that case, for example, a forced air cooling fan may be used instead of the solenoid valve. Further, a gas other than air may be used as the refrigerant.

(Other embodiments)
Further, in the above-described embodiment, an example in which the inverter device according to the present application is applied to the gradient magnetic field power supply of the MRI device has been described, but the embodiment is not limited to this. For example, the inverter device according to the present application can be similarly applied to other types of devices that require a high output inverter device. For example, the inverter device according to the present application can be similarly applied to other medical image diagnostic devices such as an X-ray CT (Computed Tomography) device, a PET (Positron Emission Tomography) device, and an X-ray diagnostic device. Further, for example, the inverter device according to the present application can be similarly applied to an electric vehicle, a hybrid vehicle, a machine tool, and the like.

In this case, for example, the control function 24b controls the flow rate of the refrigerant at a frequency according to the system to which the inverter device is applied or the application of the inverter device. For example, when the responsiveness of the cooling control is important, the control function 24b controls the flow rate of the refrigerant at fine time intervals so that the cooling control can be made to follow the sudden temperature rise. .. Further, for example, when stability is important, the control function 24b controls the flow rate of the refrigerant at regular intervals where temperature stability and balance are required.

Further, in the above-described embodiment, an example in which the monitoring unit and the control unit in the present specification are realized by the monitoring function 24a and the control function 24b of the processing circuit 24 has been described, but the embodiment is not limited to this. For example, the monitoring unit and control in the present specification are realized by the monitoring function 24a and the control function 24b described in the embodiment, and also have the same function by hardware only, software only, or a mixture of hardware and software. It does not matter if it realizes.

Further, the word "processor" used in the description of each of the above-described embodiments is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an integrated circuit for a specific application (Application Specific Integrated Circuit: ASIC). , Circuits such as programmable logic devices (eg, Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). Means. Here, instead of storing the program in the storage circuit, the program may be configured to be directly embedded in the circuit of the processor. In this case, the processor realizes the function by reading and executing the program embedded in the circuit. Further, each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, and a plurality of independent circuits may be combined to be configured as one processor to realize its function. good.

Here, the program executed by the processor is provided by being incorporated in a ROM (Read Only Memory), a storage circuit, or the like in advance. This program is a file in a format that can be installed or executed on these devices, such as CD (Compact Disk) -ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk), etc. It may be recorded and provided on a computer-readable storage medium. Further, this program may be stored on a computer connected to a network such as the Internet, and may be provided or distributed by being downloaded via the network. For example, this program is composed of modules including each of the above-mentioned functional parts. As actual hardware, the CPU reads a program from a storage medium such as a ROM and executes the program, so that each module is loaded on the main storage device and generated on the main storage device.

According to at least one embodiment described above, the inverter device can be stably operated and the risk of device damage can be reduced.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

100 MRI device 3 gradient magnetic field power supply 20 inverter device 21a to 21h 1st to 8th power devices 24 processing circuit 24a monitoring function 24b control function 25 water cooling plate 26 solenoid valve

Claims (13)

With multiple power devices connected in parallel,
An inverter device including a control unit that controls the flow rate of the refrigerant that cools each power device so as to suppress the bias of heat generation between the power devices. The plurality of power devices are mounted, and a cooling plate having a plurality of flow paths provided for each power device is further provided.
The control unit controls the flow rate of the refrigerant flowing in each of the plurality of flow paths.
The inverter device according to claim 1. Further, a solenoid valve provided for each flow path of the cooling plate and having a plurality of valves for circulating a refrigerant in each flow path is further provided.
The control unit controls the flow rate of the refrigerant by controlling each valve of the solenoid valve.
The inverter device according to claim 2. The control unit dynamically controls the flow rate of the refrigerant during the operation of the inverter device.
The inverter device according to any one of claims 1 to 3. It is further equipped with a monitoring unit that monitors the temperature of each power device or the temperature of the measurement site that indirectly indicates the temperature of each power device.
The control unit controls the flow rate of the refrigerant based on the temperature.
The inverter device according to any one of claims 1 to 4. The control unit predicts the reached temperature from the change in the transition state of the temperature, and controls the flow rate of the refrigerant based on the reached temperature.
The inverter device according to claim 5. The control unit predicts the ultimate temperature based on the change in temperature and the temperature time constant of each power device or each measurement site.
The inverter device according to claim 6. The plurality of power devices are of different types and
The control unit controls the flow rate of the refrigerant according to the cooling conditions required according to the operation of each power device.
The inverter device according to any one of claims 1 to 7. The control unit controls the flow rate of the refrigerant at a frequency according to the system to which the inverter device is applied or the application of the inverter device.
The inverter device according to any one of claims 1 to 8. The control unit performs feed-forward control of the flow rate of the refrigerant by predicting the magnitude of heat generation generated in each power device based on the operation information of the inverter device.
The inverter device according to any one of claims 1 to 9. The inverter device is applied to a gradient magnetic field power supply of a magnetic resonance imaging device.
The control unit uses information indicating the waveform of the current output from the gradient magnetic field power supply to the gradient magnetic field coil as the operation information.
The inverter device according to claim 10. The gradient magnetic field coil of the magnetic resonance imaging device is equipped with an inverter device that outputs a voltage according to the waveform of the gradient magnetic field.
The inverter device is
With multiple power devices connected in parallel,
A gradient magnetic field power source having a control unit that controls the flow rate of the refrigerant that cools each power device so as to suppress the bias of heat generation between the power devices. A gradient magnetic field coil that applies a gradient magnetic field to the imaging space in which the subject is placed,
A gradient magnetic field power source having an inverter device that outputs a voltage corresponding to the waveform of the gradient magnetic field to the gradient magnetic field coil is provided.
The inverter device is
With multiple power devices connected in parallel,
A magnetic resonance imaging device having a control unit that controls the flow rate of the refrigerant that cools each power device so as to suppress the bias of heat generation between the power devices.

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