Modulation method of gradient amplifier circuit, electronic equipment and computer storage medium

Abstract

The invention discloses a modulation method of a gradient amplifier circuit, electronic equipment and a computer storage medium. The modulation method comprises the following steps: acquiring an inductive current and an instruction current of a gradient amplifier circuit; obtaining an output modulation ratio of the gradient amplifier circuit based on the inductive current and the instruction current; the modulation mode of the gradient amplifier circuit is switched based on the output modulation ratio to reduce the switching loss of the gradient amplifier circuit. Through the mode, the modulation mode of the circuit can be switched through the output modulation ratio of the gradient amplifier circuit, so that the high-frequency switching frequency of a switch tube of the whole circuit is reduced, the loss of the switch tube is reduced, and the efficiency of the gradient amplifier circuit is improved.

Description

Technical Field

[0001] This application relates to the technical field of gradient amplifier circuits, and particularly to a modulation method for a gradient amplifier circuit, an electronic device, and a computer storage medium. Background Art

[0002] The load of the gradient amplifier circuit is a gradient coil, which can be equivalent to an inductor. The load is generally fixed. In the prior art, it is generally required that the inductor current output by the inductor tracks the command current to complete rapid rise and fall. The inductor current is also called the gradient current. When the inductor current ramps up, a large voltage is usually output to support the rapid rise of the inductor current. After the inductor current rises to the steady state, a large output voltage is usually not required, and only a little voltage needs to be output to maintain the stability of the inductor current. However, in the prior art, in both the inductor current rising stage and the steady state stage, all bridge branches of the gradient amplifier circuit adopt high-frequency modulation, and the loss of the switching tubes is relatively serious. Summary of the Invention

[0003] This application provides a modulation method for a gradient amplifier circuit, an electronic device, and a computer storage medium, aiming to solve the above problems.

[0004] To solve the above technical problems, a technical solution adopted by this application is: to provide a modulation method for a gradient amplifier circuit, the modulation method includes: obtaining the inductor current and the command current of the gradient amplifier circuit; obtaining the output modulation ratio of the gradient amplifier circuit based on the inductor current and the command current; switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio to reduce the switching loss of the gradient amplifier circuit.

[0005] Among them, the modulation mode includes a full-power modulation mode and a low-power consumption modulation mode; the step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio includes: obtaining the current modulation mode of the gradient amplifier circuit; in response to the current modulation mode being the full-power modulation mode, determining whether the inductor current enters the steady state; in response to the inductor current entering the steady state, determining whether the absolute value of the output modulation ratio is less than a first preset ratio; in response to the absolute value of the output modulation ratio being less than the first preset ratio, switching the modulation mode of the gradient amplifier circuit to the low-power consumption modulation mode; among them, the number of conducting bridge branches of the gradient amplifier circuit in the low-power consumption modulation mode is less than the number of conducting bridge branches of the gradient amplifier circuit in the full-power modulation mode.

[0006] Among them, the step of determining whether the inductor current enters the steady state includes: determining whether the inductor current is greater than the absolute value of the product of the command current and a preset ratio; in response to the inductor current being greater than the absolute value of the product of the command current and the preset ratio, determining whether the inductor current enters the steady state.

[0007] Among them, the low-power modulation mode includes a first low-power modulation mode. The step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio further includes: in response to the current modulation mode being the first low-power modulation mode, determining whether the inductor current has completely entered the steady state; in response to the inductor current not having completely entered the steady state, determining whether the output modulation ratio is greater than or equal to a second preset ratio; in response to the output modulation ratio being greater than or equal to the second preset ratio, switching the modulation mode of the gradient amplifier circuit to the full-power modulation mode.

[0008] Among them, the low-power modulation mode includes a second low-power modulation mode. After the step of determining whether the inductor current has completely entered the steady state in response to the current modulation mode being the first low-power modulation mode, the step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio further includes: in response to the inductor current having completely entered the steady state, determining whether the absolute value of the output modulation ratio is less than a third preset ratio; in response to the absolute value of the output modulation ratio being less than the third preset ratio, switching the modulation mode of the gradient amplifier circuit to the second low-power modulation mode; wherein, the number of conducting bridge branches of the gradient amplifier circuit in the second low-power modulation mode is less than that in the first low-power modulation mode.

[0009] Among them, the step of determining whether the inductor current has completely entered the steady state includes: determining whether the absolute value of the difference between the filtered value of the inductor current and the command current is less than a preset difference; in response to the absolute value of the difference between the filtered value of the inductor current and the command current being less than the preset difference, determining that the inductor current has completely entered the steady state; in response to the difference between the filtered value of the inductor current and the command current being greater than or equal to the preset difference, determining that the inductor current has not completely entered the steady state.

[0010] Among them, the low-power modulation mode includes a first low-power modulation mode and a second low-power modulation mode. The step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio further includes: in response to the current modulation mode being the second low-power modulation mode, determining whether the output modulation ratio is greater than or equal to a fourth preset ratio; in response to the output modulation ratio being greater than or equal to the fourth preset ratio, switching the modulation mode of the gradient amplifier circuit to the first low-power modulation mode; wherein, the number of conducting bridge branches of the gradient amplifier circuit in the second low-power modulation mode is less than that in the first low-power modulation mode.

[0011] Among them, the step of obtaining the output modulation ratio of the gradient amplifier circuit based on the inductor current and the command current includes: obtaining the inductor voltage of the gradient amplifier circuit based on the inductor current and the command current; obtaining the feedforward voltage of the gradient amplifier circuit, and obtaining the output voltage of the gradient amplifier circuit based on the feedforward voltage and the inductor voltage; obtaining the output modulation ratio based on the output voltage and the power supply voltage.

[0012] To solve the above technical problems, another technical solution adopted by this application is: to provide an electronic device, which includes a processor and a memory connected to the processor. Among them, program data is stored in the memory, and the processor executes the program data stored in the memory to execute the modulation method of the gradient amplifier circuit described in any one of the above.

[0013] To solve the above technical problems, another technical solution adopted by this application is: to provide a computer-readable storage medium, which stores program instructions internally, and the program instructions are executed by the processor to implement the modulation method of the gradient amplifier circuit described in any one of the above.

[0014] The beneficial effect of this application is: different from the prior art, the modulation method of the gradient amplifier circuit in this application first obtains the inductor current and command current of the gradient amplifier circuit, then obtains the output modulation ratio of the gradient amplifier circuit based on the inductor current and command current, and finally switches the modulation mode of the gradient amplifier circuit based on the output modulation ratio to reduce the switching loss of the gradient amplifier circuit. In the above manner, the modulation method of the gradient amplifier circuit in this application can switch the modulation mode of the gradient amplifier circuit based on the output modulation ratio, and when the inductor current is in the steady state stage, switch the corresponding modulation mode as needed to reduce the high-frequency switching times of the overall circuit switching tube, thereby reducing the loss of the switching tube and improving the efficiency of the gradient amplifier circuit. Description of the Drawings

[0015] The drawings here are incorporated into the specification and constitute a part of this specification. These drawings show embodiments consistent with this application and are used together with the specification to illustrate the technical solutions of this application.

[0016] Figure 1 is a schematic circuit diagram of an embodiment of the gradient amplifier circuit of this application;

[0017] Figure 2 is a schematic flowchart of the first embodiment of the modulation method of the gradient amplifier circuit of this application;

[0018] Figure 3 is Figure 2 a schematic flowchart of the first embodiment of step S103 in

[0019] Figure 4 is Figure 3 a schematic flowchart of an embodiment of step S202 in

[0020] Figure 5 is Figure 2 a schematic flowchart of the second embodiment of step S103 in

[0021] Figure 6 is Figure 2Flow schematic diagram of the third embodiment of step S103;

[0022] Figure 7 Is Figure 5 Flow schematic diagram of one embodiment of step S401;

[0023] Figure 8 Is Figure 2 Flow schematic diagram of the fourth embodiment of step S103;

[0024] Figure 9 Is the flow schematic diagram of a specific implementation scheme of the modulation method of the gradient amplifier circuit of the present application;

[0025] Figure 10 Is Figure 1 Waveform schematic diagram of one embodiment of the modulation module in the full - power modulation mode of the gradient amplifier circuit;

[0026] Figure 11 Is Figure 1 Waveform schematic diagram of one embodiment of the modulation module in the first low - power modulation mode of the gradient amplifier circuit;

[0027] Figure 12 Is Figure 1 Waveform schematic diagram of the first embodiment of the modulation module in the second low - power modulation mode of the gradient amplifier circuit;

[0028] Figure 13 Is Figure 1 Waveform schematic diagram of the second embodiment of the modulation module in the second low - power modulation mode of the gradient amplifier circuit;

[0029] Figure 14 Is Figure 1 Waveform schematic diagram of the third embodiment of the modulation module in the second low - power modulation mode of the gradient amplifier circuit;

[0030] Figure 15 Is Figure 2 Flow schematic diagram of one embodiment of step S102;

[0031] Figure 16 Is the control block diagram of one embodiment of the gradient amplifier circuit of the present application;

[0032] Figure 17 Is the structural schematic diagram of one embodiment of the electronic device of the present application;

[0033] Figure 18 Is the structural schematic diagram of one embodiment of the computer storage medium of the present application. Detailed implementation manners

[0034] The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description of the specification, claims and above drawings of this application are intended to cover non-exclusive inclusion.

[0036] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality" means more than two unless otherwise specifically defined.

[0037] Referring to "embodiment" herein means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0038] Please refer to Figure 1 , Figure 1 which is a schematic circuit diagram of an embodiment of the gradient amplifier circuit of this application. As Figure 1 shown, the gradient amplifier circuit 100 of this embodiment includes three H-bridge branches, and each H-bridge branch includes four switching tubes. Among them, the load of the gradient amplifier circuit 100 is a gradient coil, which can be equivalent to an inductor L gc , and the load is generally fixed. In the prior art, it is generally required that the inductor current output by the inductor tracks the command current to complete rapid rise and fall. The inductor current is also called the gradient current. When the inductor current ramps up, a large voltage is usually output to support the rapid rise of the inductor current. After the inductor current rises to the steady state, a large output voltage is usually not required, and only a little voltage needs to be output to maintain the stability of the inductor current. However, in the prior art, whether in the inductor current rising stage or in the steady state stage, all H-bridge branches of the gradient amplifier circuit 100 adopt high-frequency modulation, and the loss of the switching tubes is relatively serious.

[0039] To solve the above problems, the present application first proposes a modulation method for a gradient amplifier circuit. Please refer to Figure 2 ,Figure 2 It is a schematic flowchart of the first embodiment of the modulation method for the gradient amplifier circuit of the present application. As Figure 2 shown, the modulation method for the gradient amplifier circuit in this embodiment specifically includes steps S101 to S103:

[0040] Step S101: Obtain the inductor current and command current of the gradient amplifier circuit.

[0041] In this embodiment, during the modulation of the gradient amplifier circuit, first, the command current of the control system needs to be obtained, and at the same time, current sampling of the gradient amplifier circuit is also required to obtain the current inductor current of the gradient amplifier circuit.

[0042] Step S102: Obtain the output modulation ratio of the gradient amplifier circuit based on the inductor current and the command current.

[0043] After obtaining the current inductor current of the gradient amplifier circuit and the command current corresponding to the system command, the error signal between the two can be calculated. By adjusting the error signal, the inductor voltage corresponding to the gradient amplifier circuit can be obtained. At this time, based on the input feedforward undervoltage and the inductor voltage, the two are added to obtain the output voltage of the gradient amplifier circuit. At this time, based on the output voltage and the power supply voltage, the output modulation ratio of the gradient amplifier circuit can be calculated.

[0044] Step S103: Switch the modulation mode of the gradient amplifier circuit based on the output modulation ratio to reduce the switching loss of the gradient amplifier circuit.

[0045] After obtaining the output modulation ratio of the gradient amplifier circuit, the modulation mode of the gradient amplifier circuit can be switched based on the output modulation ratio and combined with the corresponding state of the current gradient amplifier circuit. If the inductor current of the gradient amplifier circuit is in the ramp state, then switching to the full-power modulation mode will output a large voltage to support the rapid rise of the inductor current. If the inductor current of the gradient amplifier circuit has completed the rise and is stable, then a large output voltage is not required, and only a little voltage needs to be output to maintain the stability of the inductor current. At this time, the low-power consumption modulation mode can be switched to output the output voltage to maintain the inductor current. The specific switching method is described below and will not be elaborated here.

[0046] Among them, the gradient amplifier circuit includes multiple bridge branches. In this embodiment, the output voltage of the gradient amplifier circuit can be controlled by controlling the number of conducting bridge branches. In this implementation, the number of conducting bridge branches of the gradient amplifier circuit in the low-power modulation mode is less than that in the full-power modulation mode. Therefore, after the inductor current of the gradient amplifier circuit rises and stabilizes, switching to the low-power modulation mode can reduce the high-frequency switching times of the overall circuit switching transistors, thereby reducing the loss of the switching transistors.

[0047] Different from the prior art, the modulation method of the gradient amplifier circuit of the present application first obtains the inductor current and the command current of the gradient amplifier circuit, then obtains the output modulation ratio of the gradient amplifier circuit based on the inductor current and the command current, and finally switches the modulation mode of the gradient amplifier circuit based on the output modulation ratio to reduce the switching loss of the gradient amplifier circuit. In the above manner, the modulation method of the gradient amplifier circuit of the present application can switch the modulation mode of the gradient amplifier circuit based on the output modulation ratio, and when the inductor current is in the steady state stage, switch the corresponding modulation mode as needed to reduce the high-frequency switching times of the overall circuit switching transistors, thereby reducing the loss of the switching transistors and improving the efficiency of the gradient amplifier circuit.

[0048] Among them, the number of conducting bridge branches of the gradient amplifier circuit in the low-power modulation mode is less than that in the full-power modulation mode.

[0049] Optionally, the method for switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio is as Figure 3 shown. Please refer to Figure 3 , Figure 3 which Figure 2 is the flowchart of the first embodiment of step S103 in Figure 3 . Among them, in this embodiment, the modulation mode includes the full-power modulation mode and the low-power modulation mode. This embodiment can implement step S103 through the method shown in

[0050] Step S201: Obtain the current modulation mode of the gradient amplifier circuit.

[0051] As described above, the modulation mode of the gradient amplifier circuit includes the full-power modulation mode and the low-power modulation mode. Among them, the number of conducting bridge branches of the gradient amplifier circuit in the low-power modulation mode is less than that in the full-power modulation mode, and in this embodiment, all the bridge branches of the gradient amplifier circuit in the full-power modulation mode are conducting to support the inductor current to quickly reach the command current. Therefore, in the initial state of the gradient amplifier circuit, the modulation mode is generally set to the full-power modulation mode.

[0052] In this embodiment, when the inductor current of the gradient amplifier circuit reaches a steady state from the rising state or when the inductor current of the gradient amplifier circuit is in a steady state and the command current changes, that is, when the output demand of the gradient amplifier circuit changes, it is necessary to switch the modulation mode of the gradient amplifier circuit. Before switching, it is first necessary to obtain the current modulation mode of the gradient amplifier circuit.

[0053] Step S202: In response to the current modulation mode being the full-power modulation mode, determine whether the inductor current enters a steady state.

[0054] If the current modulation mode of the gradient amplifier circuit is the full-power modulation mode, it is necessary to obtain the inductor current of the current gradient amplifier circuit at this time and determine whether the inductor current enters a steady state. The method for determining whether the inductor current enters a steady state is as described below and will not be elaborated here.

[0055] Step S203: In response to the inductor current entering a steady state, determine whether the absolute value of the output modulation ratio is less than a first preset ratio.

[0056] If the inductor current of the gradient amplifier circuit enters a steady state, it is also necessary to determine whether the absolute value of the output modulation ratio of the gradient amplifier circuit is less than a first preset ratio.

[0057] Among them, the first preset ratio is the ratio of the preset modulation duty cycle to the current number of conducting bridge branches of the gradient amplifier circuit. In this embodiment, the preset modulation duty cycle can be set to 0.5. In other embodiments, the preset modulation duty cycle can also be set based on actual conditions and will not be limited here.

[0058] If the absolute value of the output modulation ratio is less than the first preset ratio, go to step S203; if the absolute value of the output modulation ratio is greater than or equal to the first preset ratio, maintain the modulation mode of the gradient amplifier circuit as the full-power modulation mode.

[0059] Step S204: Switch the modulation mode of the gradient amplifier circuit to the low-power modulation mode.

[0060] When the inductor current enters a steady state and the absolute value of the output modulation ratio of the gradient amplifier circuit is less than the first preset ratio, it indicates that there is a surplus in the output of all the conducting bridge branches of the gradient amplifier circuit in the current state. At this time, some bridge branches of the gradient amplifier circuit can be bypassed, so as to realize switching the modulation mode of the gradient amplifier circuit to the low-power modulation mode. In addition, when performing the action of switching and bypassing the bridge branches, it is necessary to switch the bridge branches one by one to avoid the impact on the gradient amplifier circuit when multiple bridge branches are bypassed simultaneously.

[0061] Optionally, based on Figure 3For the embodiments, the method for determining whether the inductor current enters a steady state is as follows Figure 4 shown. Please refer to Figure 4 , Figure 4 which Figure 3 is a schematic flowchart of an embodiment of step S202 in Figure 4 shown. In this embodiment, step S202 can be implemented by the method as Figure 4 shown. The specific implementation steps include steps S301 to S302:

[0062] Step S301: Determine whether the inductor current is greater than the absolute value of the product of the command current and the preset ratio.

[0063] As described above, based on Figure 3 the embodiments, if the current modulation mode of the gradient amplifier circuit is the full-power modulation mode and a modulation mode switch is required, it is necessary to determine whether the inductor current enters a steady state. In this embodiment, that is, to determine whether the inductor current is greater than the absolute value of the product of the command current and the preset ratio. Among them, in this embodiment, the preset ratio can be set to 95%, and in other embodiments, the preset ratio can also be set between 90% and 99%, which is not limited here.

[0064] Step S302: In response to the inductor current being greater than the absolute value of the product of the command current and the preset ratio, determine whether the inductor current enters a steady state.

[0065] If the inductor current of the gradient amplifier circuit is greater than the absolute value of the product of the command current and the preset ratio, determine whether the inductor current of the gradient amplifier circuit enters a steady state.

[0066] Optionally, based on the above embodiments, the method for switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio is as Figure 5 shown. Please refer to Figure 5 , Figure 5 which Figure 2 is a schematic flowchart of a second embodiment of step S103 in Figure 5 shown. Among them, in this embodiment, the modulation modes include the full-power modulation mode and the low-power consumption modulation mode, and the low-power consumption modulation mode includes the first low-power consumption modulation mode. This embodiment can implement step S103 by the method as

[0067] Step S401: In response to the current modulation mode being the first low-power consumption modulation mode, determine whether the inductor current completely enters a steady state.

[0068] In this embodiment, the modulation modes of the gradient amplifier circuit include a full-power modulation mode and a first low-power consumption modulation mode. Among them, the number of conducting bridge branches of the gradient amplifier circuit in the first low-power consumption modulation mode is less than that in the full-power modulation mode.

[0069] When the output requirement of the gradient amplifier circuit changes, if the current modulation mode of the gradient amplifier circuit is the first low-power consumption modulation mode, it is also necessary to obtain the inductor current of the current gradient amplifier circuit and determine whether the inductor current has completely entered the steady state. The method for determining whether the inductor current has completely entered the steady state is as described below and will not be elaborated here.

[0070] Step S402: In response to the inductor current not completely entering the steady state, determine whether the output modulation ratio is greater than or equal to a second preset ratio.

[0071] In this embodiment, if the inductor current has not completely entered the steady state, it is necessary to determine whether the output modulation ratio of the gradient amplifier circuit is greater than or equal to the second preset ratio.

[0072] Among them, the second preset ratio is a preset modulation duty cycle. In this embodiment, the preset modulation duty cycle can be set to 0.5. In other embodiments, the preset modulation duty cycle can also be set based on actual conditions and will not be limited here.

[0073] If the output modulation ratio is greater than or equal to the second preset ratio, go to step S403; if the output modulation ratio is less than the first preset ratio, maintain the modulation mode of the gradient amplifier circuit as the first low-power consumption modulation mode.

[0074] Step S403: Switch the modulation mode of the gradient amplifier circuit to the full-power modulation mode.

[0075] When the inductor current has not completely entered the steady state, it indicates that the difference between the inductor current and the command current of the gradient amplifier circuit is too large under the current state. At this time, the output capacity of the conducting bridge branches of the gradient amplifier circuit is insufficient, and it is still necessary to output a voltage in the full-power modulation mode to make the inductor current quickly reach the command current. At this time, all the bridge branches of the gradient amplifier circuit are turned on, so as to realize the switching of the modulation mode of the gradient amplifier circuit from the first low-power consumption modulation mode to the full-power modulation mode. In addition, when turning on the bypassed bridge branches, they need to be switched one by one to avoid the impact on the gradient amplifier circuit when multiple bridge branches are turned on simultaneously.

[0076] Optionally, based on the above embodiment, the method for switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio is as Figure 6 shown, please refer to Figure 6 , Figure 6 is Figure 2Flow diagram of the third embodiment of step S103. In this embodiment, the modulation modes include a full-power modulation mode and a low-power modulation mode, and the low-power modulation mode includes a first low-power modulation mode and a second low-power modulation mode. This embodiment can implement step S103 through the method as shown in Figure 6 The specific implementation steps include steps S501 to S503:

[0077] Step S501: In response to the current modulation mode being the first low-power modulation mode, determine whether the inductor current has completely entered a steady state.

[0078] Step S501 is the same as step S401 and will not be elaborated here.

[0079] Step S502: In response to the inductor current having completely entered a steady state, determine whether the absolute value of the output modulation ratio is less than a third preset ratio.

[0080] In this embodiment, the modulation modes of the gradient amplifier circuit include a full-power modulation mode, a first low-power modulation mode, and a second low-power modulation mode. Among them, the number of conducting bridge branches of the gradient amplifier circuit in the second low-power modulation mode is less than the number of conducting bridge branches of the gradient amplifier circuit in the first low-power modulation mode; the number of conducting bridge branches of the gradient amplifier circuit in the first low-power modulation mode is less than the number of conducting bridge branches of the gradient amplifier circuit in the full-power modulation mode.

[0081] When the output demand of the gradient amplifier circuit changes, if the current modulation mode of the gradient amplifier circuit is the first low-power modulation mode, it is also necessary to obtain the inductor current of the current gradient amplifier circuit and determine whether the inductor current has completely entered a steady state.

[0082] In this embodiment, if the inductor current has completely entered a steady state, it is necessary to determine whether the absolute value of the output modulation ratio of the gradient amplifier circuit is less than a third preset ratio.

[0083] Among them, the third preset ratio is the ratio of the preset modulation duty cycle to the number of currently conducting bridge branches of the gradient amplifier circuit. In this embodiment, the preset modulation duty cycle can be set to 0.5. In other embodiments, the preset modulation duty cycle can also be set based on actual situations and is not limited here.

[0084] If the absolute value of the output modulation ratio is less than the third preset ratio, go to step S503; if the absolute value of the output modulation ratio is greater than or equal to the third preset ratio, maintain the modulation mode of the gradient amplifier circuit as the first low-power modulation mode.

[0085] Step S503: Switch the modulation mode of the gradient amplifier circuit to the second low-power modulation mode.

[0086] When the inductor current has completely entered the steady state and the absolute value of the output modulation ratio of the gradient amplifier circuit is less than the third preset ratio, it indicates that there is still margin in the output of the conducting bridge branch of the gradient amplifier circuit in the current state. At this time, part of the bridge branch of the conducting bridge branch of the gradient amplifier circuit can be bypassed, so as to realize the switching of the modulation mode of the gradient amplifier circuit from the first low-power modulation mode to the second low-power modulation mode with lower power consumption. In addition, when performing the operation of switching and bypassing the bridge branch, it is also necessary to switch the bridge branch one by one, avoiding the impact on the gradient amplifier circuit when multiple bridge branches are bypassed simultaneously.

[0087] Optionally, based on Figure 5 the embodiments shown, the method for determining whether the inductor current has completely entered the steady state is as Figure 7 shown. Please refer to Figure 7 , Figure 7 which Figure 5 is a schematic flowchart of an embodiment of step S401 in Figure 7 . As Figure 7 shown, this embodiment can implement step S401 through the method shown in

[0088] Step S601: Determine whether the absolute value of the difference between the filtered value of the inductor current and the command current is less than a preset difference.

[0089] As described above, based on Figure 5 and Figure 6 the embodiments, if the current modulation mode of the gradient amplifier circuit is the first low-power modulation mode and a modulation mode switch is required, it is necessary to determine whether the inductor current has completely entered the steady state. In this embodiment, that is, to determine whether the absolute value of the difference between the filtered value of the inductor current and the command current is less than a preset difference. Among them, in this embodiment, the preset difference can be set based on the actual situation and is not limited here.

[0090] If the absolute value of the difference between the filtered value of the inductor current and the command current is less than the preset difference, go to step S602; if the absolute value of the difference between the filtered value of the inductor current and the command current is greater than or equal to the preset difference, go to step S603.

[0091] Step S602: Determine that the inductor current has completely entered the steady state.

[0092] If the absolute value of the difference between the filtered value of the inductor current and the command current is less than the preset difference, it is determined that the inductor current of the gradient amplifier circuit has completely entered the steady state.

[0093] Step S603: Determine that the inductor current has not completely entered the steady state.

[0094] If the absolute value of the difference between the filtered value of the inductor current and the command current is greater than or equal to a preset difference, it is determined that the inductor current of the gradient amplifier circuit has not fully entered the steady state.

[0095] Optionally, based on the above embodiments, a method for switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio is as Figure 8 shown. Please refer to Figure 8 , Figure 8 which Figure 2 is the flow schematic diagram of the fourth embodiment of step S103 in Figure 8 . In this embodiment, the modulation mode includes a full-power modulation mode and a low-power consumption modulation mode, and the low-power consumption modulation mode includes a first low-power consumption modulation mode and a second low-power consumption modulation mode. This embodiment can implement step S103 through the method as

[0096] shown, and the specific implementation steps include step S701 to step S702:

[0097] Step S701: In response to the current modulation mode being the second low-power consumption modulation mode, determine whether the output modulation ratio is greater than or equal to a fourth preset ratio.

[0098] In this embodiment, the modulation mode of the gradient amplifier circuit includes a first low-power consumption modulation mode and a second low-power consumption modulation mode. Among them, the number of conducting bridge branches of the gradient amplifier circuit in the second low-power consumption modulation mode is less than the number of conducting bridge branches of the gradient amplifier circuit in the first low-power consumption modulation mode.

[0099] When the output demand of the gradient amplifier circuit changes and the current modulation mode of the gradient amplifier circuit is the first low-power consumption modulation mode, it is necessary to obtain whether the judged output modulation ratio of the current gradient amplifier circuit is greater than or equal to the fourth preset ratio.

[0100] Wherein, the fourth preset ratio is the ratio of the preset modulation duty cycle to the current number of conducting bridge branches of the gradient amplifier circuit. In this embodiment, the preset modulation duty cycle can be set to 0.5. In other embodiments, the preset modulation duty cycle can also be set based on actual situations and is not limited herein.

[0101] If the output modulation ratio is greater than or equal to the fourth preset ratio, go to step S702; if the output modulation ratio is less than the fourth preset ratio, maintain the modulation mode of the gradient amplifier circuit as the second low-power consumption modulation mode.

[0102] When the output modulation ratio of the gradient amplifier circuit is greater than or equal to the fourth preset ratio, it indicates that the gradient amplifier circuit has reached the limit value in the current state, indicating that the output capacity of the bridge branch where the gradient amplifier circuit is currently conducting is insufficient. At this time, a part of the bridge branch bypassed by the gradient amplifier circuit is conducted, so as to realize the switching of the modulation mode of the gradient amplifier circuit from the second low-power modulation mode to the first low-power modulation mode. In addition, when conducting the bypassed bridge branch, it is also necessary to switch one by one, avoiding the impact on the gradient amplifier circuit when multiple bridge branches are conducted simultaneously.

[0103] Based on all the foregoing embodiments, in an application scenario, please refer to Figure 9 , Figure 9 which is a schematic flowchart of a specific implementation of the modulation method of the gradient amplifier circuit of the present application.

[0104] In this embodiment, the modulation modes include a full-power modulation mode, a first low-power modulation mode, and a second low-power modulation mode. Among them, in practice, when Mode = 3, it represents that the gradient amplifier circuit is in the full-power modulation mode; when Mode = 2, it represents that the gradient amplifier circuit is in the first low-power modulation mode; and when Mode = 1, it represents that the gradient amplifier circuit is in the second low-power modulation mode.

[0105] In the initial state of the gradient amplifier circuit, as described above, the modulation mode should be set to the full-power modulation mode, that is, Mode = 3 at this time. At this time, the gradient amplifier circuit receives the command current iRef, and the inductor current iL of the gradient amplifier circuit starts to climb rapidly in the full-power modulation mode. Among them, in this embodiment, when the inductor current iL is less than or equal to 95% of the command current iRef, it is considered that the inductor current iL is in the climbing stage; when the inductor current iL is greater than 95% of the command current iRef, it is considered that the inductor current iL is in the steady state. As described above, in order to make the inductor current iL quickly reach the command current iRef, in the current climbing stage, Mode = 3 is set, that is, the gradient amplifier circuit is in the full-power modulation mode, and all bridge branches are conducted.

[0106] Taking the Figure 1 gradient amplifier circuit as an example, please refer to Figure 10 , Figure 10 which is Figure 1 a schematic waveform diagram of an embodiment of the modulation module in the full-power modulation mode of the gradient amplifier circuit. As Figure 10 shown, Figure 1The carrier phase shift method is adopted between the H-bridges of the gradient amplifier circuit, and the PWM waves of the two arms inside the H-bridge are phase-shifted by 180 degrees. In the full-power modulation mode, that is, when Mode = 3, all H-bridges participate in the voltage output, so a higher voltage can be provided to support the rapid rise of the inductor current iL. When the inductor current iL reaches a steady state, the gradient amplifier circuit does not need to output a large voltage, and only needs to provide a voltage to maintain the magnitude of the inductor current iL. Therefore, at this time, the H-bridges can be bypassed as needed, and only the minimum number of H-bridges required to maintain the current output is retained. The specific judgment method and Mode switching are as Figure 9 shown.

[0107] As Figure 9 shown, detect the current Mode value. When Mode = 3, taking the gradient amplifier circuit in Figure 1 as an example, Figure 1 the number Num of H-bridges (bridge branches) in it is 3. If the output inductor current iL of the gradient amplifier circuit is greater than the absolute value of 95% of the command current iRef, then it is determined that the inductor current iL is close to the steady state at this time. At this time, judge whether the absolute value of the output modulation ratio duty of the gradient amplifier circuit is less than 0.5 / Num. If the absolute value of the output modulation ratio duty is less than 0.5 / Num, it means that there is surplus in the output of all H-bridges in the current state of the gradient amplifier circuit, that is, the H-bridges can be bypassed, that is, the full-power modulation mode is switched to the first low-power modulation mode, and at this time Mode = 2; if the output inductor current iL of the gradient amplifier circuit is less than or equal to the absolute value of 95% of the command current iRef or the absolute value of the output modulation ratio duty is greater than or equal to 0.5 / Num, the modulation mode is maintained as the full-power modulation mode, that is, Mode = 3 is maintained.

[0108] Please refer to Figure 11 , Figure 11 which Figure 1 is a schematic waveform diagram of an embodiment of the modulation module in the first low-power modulation mode of the gradient amplifier circuit. At this time, the waveform of the modulation module is as Figure 11 shown. Taking the gradient amplifier circuit in Figure 1 as an example, at this time, the upper tubes S31 and S33 of the 3rd H-bridge output 0, that is, they are in the off state, so the complementary lower tubes S32 and S34 are always on, and the 3rd H-bridge is bypassed, and its output voltage is 0.

[0109] When Mode = 2, the inductor current iL of the gradient amplifier circuit can be obtained, and it is determined whether the output inductor current iL has completely entered the steady state according to the difference between the filtered value iLFilt of the inductor current iL and the command current iRef. Among them, in this embodiment, that is, it is determined whether iLFilt is greater than the absolute value of the difference between the command current iRef and 5. If iLFilt is greater than the absolute value of the difference between the command current iRef and 5, the inductor current iL has completely entered the steady state; if iLFilt is less than or equal to the absolute value of the difference between the command current iRef and 5, the inductor current iL has not completely entered the steady state. Among them, 5 is a preset difference value, which can be set based on actual conditions and is not limited here.

[0110] When Mode = 2 and the inductor current iL has completely entered the steady state, the number of H-bridges Num output by the modulation module is 2; at this time, it is necessary to determine whether the absolute value of the output modulation ratio duty of the gradient amplifier circuit is less than 0.5 / Num. If the absolute value of the output modulation ratio duty is greater than or equal to 0.5 / Num, the modulation mode is maintained as the first low-power modulation mode, that is, Mode = 2 is maintained; if the absolute value of the output modulation ratio duty is less than 0.5 / Num; then it means that there is still a margin in the output of the H-bridges participating in the modulation module output in the current state, that is, the conducting H-bridges can be bypassed further. At this time, the second low-power modulation mode can be switched to, and at this time Mode = 1. Please refer to Figure 12 , Figure 12 is Figure 1 The waveform schematic diagram of the first embodiment of the modulation module in the second low-power modulation mode of the gradient amplifier circuit. At this time, the waveform of the modulation module is as Figure 12 shown. At this time, only one H-bridge is conducting and the rest are bypassed. On the contrary, when Mode = 2 and the inductor current iL has not completely entered the steady state, it is necessary to determine whether the output modulation ratio duty of the gradient amplifier circuit is greater than or equal to 0.5. If the output modulation ratio duty is greater than or equal to 0.5, it means that the output capacity of the gradient amplifier circuit is insufficient under the current number of H-bridges. At this time, the full-power modulation mode can be switched to, that is, Mode = 3; if the output modulation ratio duty is less than 0.5, the modulation mode is maintained as the first low-power modulation mode, that is, Mode = 2 is maintained.

[0111] Please refer to Figure 13 and Figure 14 , Figure 13 is Figure 1 The waveform schematic diagram of the second embodiment of the modulation module in the second low-power modulation mode of the gradient amplifier circuit, Figure 14 is Figure 1 The waveform schematic diagram of the third embodiment of the modulation module in the second low-power modulation mode of the gradient amplifier circuit. In other embodiments, the waveform of the modulation module with Mode = 1 can also beFigure 13 or Figure 14 。

[0112] When Mode = 1, only one H-bridge is conducting at this time, and the rest are bypassed. At this time, it is necessary to determine whether the output modulation ratio duty of the gradient amplifier circuit is greater than or equal to 0.5. If the output modulation ratio duty is greater than or equal to 0.5, it means that the output capacity of the gradient amplifier circuit is insufficient under the current number of H-bridges. At this time, it can be switched to the first low-power modulation mode, that is, Mode = 2; if the output modulation ratio duty is less than 0.5, the modulation mode is maintained as the second low-power modulation mode, that is, Mode = 1 is maintained.

[0113] Optionally, the method for obtaining the output modulation ratio of the gradient amplifier circuit based on the inductor current and the command current is as Figure 15 shown. Please refer to Figure 15 , Figure 15 is Figure 2 a schematic flowchart of an embodiment of step S102 in Figure 15 shown. As Figure 15 shown, this embodiment can implement step S102 through the method shown in

[0114] Step S801: Obtain the inductor voltage of the gradient amplifier circuit based on the inductor current and the command current.

[0115] After sampling to obtain the inductor current of the gradient amplifier circuit, that is, obtaining the command current of the system, the error signal between the two can be calculated, and through a PI regulator or a PID regulator, the corresponding inductor voltage of the gradient amplifier circuit can be obtained.

[0116] Step S802: Obtain the feedforward voltage of the gradient amplifier circuit, and obtain the output voltage of the gradient amplifier circuit based on the feedforward voltage and the inductor voltage.

[0117] To enable the gradient amplifier circuit to quickly output the voltage steady-state value, a feedforward voltage needs to be added. After adding the inductor voltage and the feedforward voltage, the output voltage of the gradient amplifier circuit can be obtained. Among them, the feedforward voltage is obtained by multiplying the impedance parameter in the model of the gradient amplifier circuit by the target current value. Due to the errors of the line impedance R and the inductor Lgc, the calculated feedforward voltage value also has errors. However, by adding the output of the inductor voltage, the errors can be eliminated, and finally the inductor current can reach the command current.

[0118] Step S803: Obtain the output modulation ratio based on the output voltage and the power supply voltage.

[0119] In the output voltage of the gradient amplifier circuit, dividing the output voltage by the power supply voltage can obtain the output modulation ratio of the gradient amplifier circuit.

[0120] In an application scenario, please refer to Figure 16 , Figure 16 which is a control block diagram of an embodiment of the gradient amplifier circuit of the present application.

[0121] As Figure 16 shown, an error signal is calculated according to the system received command current iRef and the circuit sampled inductor current iL. The error signal can obtain the corresponding inductor voltage through a PI regulator (or a PID regulator). Among them, in order to make the system quickly output the voltage steady-state value, a feed-forward voltage needs to be added, and after adding it to the inductor voltage output by the PI, it is used as the output voltage V b . Among them, the feed-forward voltage V 前馈 is obtained by multiplying the impedance parameter in the gradient amplifier circuit by the command current iRef, and the calculation formula is as follows:

[0122]

[0123] wherein, L gc is the inductance equivalent to the gradient coil in the gradient amplifier circuit, iRef is the command circuit, t rise is the rise time, and R is the line impedance of the gradient amplifier circuit.

[0124] Due to the errors of the line impedance R and the inductance L gc and, the calculated feed-forward voltage V 前馈 has errors. However, after adding the output inductor voltage of the PI, the errors can be eliminated, and the output voltage V b can be obtained. The output voltage V b divided by the power supply voltage Vdc is the output modulation ratio duty. Adding the output modulation ratio duty to 0.5 and inputting it into the modulation module, the modulation mode of the gradient amplifier circuit can be switched and selected based on the output modulation ratio according to the modulation method of the gradient amplifier circuit described above.

[0125] Optionally, the present application further proposes an electronic device. Please refer to Figure 17 , Figure 17 which is a structural schematic diagram of an embodiment of the electronic device of the present application. The electronic device 200 includes a processor 201 and a memory 202 connected to the processor 201.

[0126] The processor 201 can also be referred to as a CPU (Central Processing Unit). The processor 201 may be an integrated circuit chip with the ability to process signals. The processor 201 can also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0127] The memory 202 is used to store the program data required for the operation of the processor 201.

[0128] The processor 201 is also used to execute the program data stored in the memory 202 to implement the modulation method of the gradient amplifier circuit in any of the above items.

[0129] Optionally, the present application further proposes a computer storage medium. Please refer to Figure 18 , Figure 18 which is a schematic structural diagram of an embodiment of the computer storage medium of the present application.

[0130] The computer storage medium 300 of the embodiment of the present application stores program instructions 310 internally, and the program instructions 310 are executed to implement the modulation method of the gradient amplifier circuit in any of the above items.

[0131] Among them, the program instructions 310 can form a program file and be stored in the above storage medium in the form of a software product, so that an electronic device (which can be a personal computer, a server, or a network device, etc.) or a processor can execute all or part of the steps of the methods in various embodiments of the present application. And the foregoing storage medium includes: various media that can store program codes such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs, or terminal devices such as computers, servers, mobile phones, and tablets.

[0132] The computer storage medium 300 of this embodiment can be, but is not limited to, a USB flash drive, an SD card, a PD optical drive, a mobile hard disk, a large-capacity floppy drive, a flash memory, a multimedia memory card, a server, etc.

[0133] In one embodiment, a computer program product or a computer program is provided. The computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer storage medium. The processor of the electronic device reads the computer instructions from the computer storage medium, and the processor executes the computer instructions, so that the electronic device executes the steps in the above method embodiments.

[0134] In addition, when the above functions are implemented in the form of software functions and sold or used as independent products, they can be stored in a storage medium readable by a mobile terminal. That is, the present application also provides a storage device storing program data, and the program data can be executed to implement the methods of the above embodiments. The storage device can be a USB flash drive, an optical disc, a server, etc. That is to say, the present application can be embodied in the form of a software product, which includes several instructions for causing an intelligent terminal to execute all or part of the steps of the methods of the various embodiments.

[0135] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0136] Any process or method description shown in the flowchart or described in other ways herein can be understood to represent an apparatus, segment, or portion of code including one or more executable instructions for implementing a specific logical function or process. And the scope of the preferred embodiments of the present application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in a reverse order according to the involved functions, rather than in the order shown or discussed. This should be understood by those skilled in the technical field to which the embodiments of the present application belong.

[0137] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definitional sequence list of executable instructions for implementing logical functions, which can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device (which can be a personal computer, server, network device, or other system that can fetch instructions from the instruction execution system, apparatus, or device and execute the instructions). For the purposes of this specification, a "computer storage medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection portion having one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable medium on which a program can be printed, as the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpretation, or otherwise processing as appropriate, and then storing it in a computer memory.

[0138] The above are only embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A modulation method for a gradient amplifier circuit, characterized in that, Including: Obtaining the inductor current and the command current of the gradient amplifier circuit; Obtaining the output modulation ratio of the gradient amplifier circuit based on the inductor current and the command current; Switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio to reduce the switching loss of the gradient amplifier circuit.

2. The modulation method of the gradient amplifier circuit according to claim 1, characterized in that The modulation mode includes a full-power modulation mode and a low-power consumption modulation mode; the step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio includes: Obtaining the current modulation mode of the gradient amplifier circuit; Responding to the current modulation mode being the full-power modulation mode, determining whether the inductor current enters a steady state; Responding to the inductor current entering the steady state, determining whether the absolute value of the output modulation ratio is less than a first preset ratio; Responding to the absolute value of the output modulation ratio being less than the first preset ratio, switching the modulation mode of the gradient amplifier circuit to the low-power consumption modulation mode; Wherein, the number of conducting bridge branches of the gradient amplifier circuit in the low-power consumption modulation mode is less than the number of conducting bridge branches of the gradient amplifier circuit in the full-power modulation mode.

3. The modulation method of the gradient amplifier circuit according to claim 2, characterized in that, The step of determining whether the inductor current enters the steady state includes: Determining whether the inductor current is greater than the absolute value of the product of the command current and a preset ratio; Responding to the inductor current being greater than the absolute value of the product of the command current and the preset ratio, determining whether the inductor current enters the steady state.

4. The modulation method of the gradient amplifier circuit according to claim 2, wherein The low-power consumption modulation mode includes a first low-power consumption modulation mode, and the step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio further includes: Responding to the current modulation mode being the first low-power consumption modulation mode, determining whether the inductor current completely enters the steady state; Responding to the inductor current not completely entering the steady state, determining whether the output modulation ratio is greater than or equal to a second preset ratio; Responding to the output modulation ratio being greater than or equal to the second preset ratio, switching the modulation mode of the gradient amplifier circuit to the full-power modulation mode.

5. The modulation method of the gradient amplifier circuit according to claim 4, characterized in that, The low-power consumption modulation mode includes a second low-power consumption modulation mode. After the step of responding to the current modulation mode being the first low-power consumption modulation mode and determining whether the inductor current completely enters the steady state, the step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio further includes: Responding to the inductor current completely entering the steady state, determining whether the absolute value of the output modulation ratio is less than a third preset ratio; Responding to the absolute value of the output modulation ratio being less than the third preset ratio, switching the modulation mode of the gradient amplifier circuit to the second low-power consumption modulation mode; Wherein, the number of conducting bridge branches of the gradient amplifier circuit in the second low-power consumption modulation mode is less than the number of conducting bridge branches of the gradient amplifier circuit in the first low-power consumption modulation mode.

6. The modulation method of the gradient amplifier circuit according to claim 4, characterized in that, The step of determining whether the inductor current completely enters the steady state includes: Determine whether the absolute value of the difference between the filtered value of the inductor current and the command current is less than a preset difference; In response to the absolute value of the difference between the filtered value of the inductor current and the command current being less than the preset difference, determine that the inductor current has fully entered the steady state; In response to the absolute value of the difference between the filtered value of the inductor current and the command current being greater than or equal to the preset difference, determine that the inductor current has not fully entered the steady state.

7. The modulation method of the gradient amplifier circuit according to claim 2, wherein The low-power modulation mode includes a first low-power modulation mode and a second low-power modulation mode. The step of switching the modulation mode of the gradient amplifier circuit based on the output modulation ratio further includes: In response to the current modulation mode being the second low-power modulation mode, determine whether the output modulation ratio is greater than or equal to a fourth preset ratio; In response to the output modulation ratio being greater than or equal to the fourth preset ratio, switch the modulation mode of the gradient amplifier circuit to the first low-power modulation mode; Wherein, the number of bridge branches turned on by the gradient amplifier circuit in the second low-power modulation mode is less than the number of bridge branches turned on by the gradient amplifier circuit in the first low-power modulation mode.

8. The modulation method of the gradient amplifier circuit according to claim 1, characterized in that The step of obtaining the output modulation ratio of the gradient amplifier circuit based on the inductor current and the command current includes: Obtain the inductor voltage of the gradient amplifier circuit based on the inductor current and the command current; Obtain the feedforward voltage of the gradient amplifier circuit, and obtain the output voltage of the gradient amplifier circuit based on the feedforward voltage and the inductor voltage; Obtain the output modulation ratio based on the output voltage and the power supply voltage.

9. An electronic device, characterized in that, The electronic device includes a processor and a memory connected to the processor. Among them, program data is stored in the memory, and the processor executes the program data stored in the memory to execute the modulation method of the gradient amplifier circuit according to any one of claims 1-8.

10. A computer storage medium, characterized in that, It internally stores program instructions, and the program instructions are executed to implement the modulation method of the gradient amplifier circuit according to any one of claims 1-8.

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