CN205450235U - Controller, drive unit , gradient coil device and magnetic resonance imaging equipment - Google Patents

Abstract

The utility model provides a controller, a drive unit, a gradient coil device and a magnetic resonance imaging device. The controller includes: a feedforward unit connected to the outside, the feedforward unit is configured to receive a reference current from the outside, and generates a feedforward voltage according to the received reference current; a feedback unit is connected to the load, and the feedback unit is configured to receive the reference current from the outside The load receives the load current, and generates a feedback voltage according to the received load current; the control voltage generating unit is connected to the feedforward unit and the feedback unit, and the control voltage generating unit is configured to receive the feedforward voltage and the feedback voltage, and generate the feedback voltage according to the received feedforward The control voltage is generated by the voltage and the feedback voltage, wherein the feedforward unit consists of analog components. Therefore, the delay caused by the feedforward unit can be significantly reduced.

Description

Controller, drive unit, gradient coil device and magnetic resonance imaging equipment

technical field

The utility model relates to a controller, a drive unit, a gradient coil device and a magnetic resonance imaging device.

Background technique

A Magnetic Resonance Imaging (MRI) apparatus generally includes a gradient coil arrangement that generates a gradient magnetic field. The gradient coil device includes a driving unit that generates a driving voltage according to a reference current received from the outside, and a gradient coil that receives the driving voltage and generates a gradient magnetic field according to the driving voltage. In order to generate a driving voltage according to a reference current, a current driving unit includes a controller for generating a control voltage according to the reference current and an amplifier for generating the driving voltage according to the control voltage. Because the electrical characteristics of the gradient coil are very complex, it is required that the controller can precisely control the amplifier. For this reason, existing controllers have adopted digital circuits. However, a controller using a digital circuit needs to include analog-to-digital (A/D) conversion of the reference current first, and digital-to-analog (D/A) conversion after processing the digital signal to obtain the control voltage as an analog signal , Therefore, a controller using a digital circuit needs a separate A/D conversion circuit and a D/A conversion circuit, resulting in a high cost. In addition, since A/D conversion and D/A conversion are required, when the reference current is adjusted to achieve precise control of the amplifier, there is a delay from the time point of the change of the reference current to the time point of the change of the control voltage, As a result, the desired gradient magnetic field cannot be obtained through the gradient coil in time.

Utility model content

Exemplary embodiments of the present invention aim to overcome the above and/or other problems of the prior art. Accordingly, exemplary embodiments of the present invention provide a controller, a driving unit, a gradient coil device, and a magnetic resonance imaging apparatus that can significantly reduce a delay caused by a feedforward unit.

According to an exemplary embodiment, there is provided a controller, the controller comprising: a feedforward unit connected to the outside, the feedforward unit is configured to receive a reference current from the outside, and generate a feedforward voltage according to the received reference current; a feedback unit connected to the load, the feedback unit is configured to receive a load current from the load, and generates a feedback voltage according to the received load current; a control voltage generation unit is connected to the feedforward unit and the feedback unit, and the control voltage generation unit is configured to receive feedforward voltage and feedback voltage, and generate a control voltage according to the received feedforward voltage and feedback voltage, wherein the feedforward unit is composed of analog components.

According to an exemplary embodiment, there is provided a driving unit, characterized in that the driving unit includes: the above-mentioned controller connected to the outside to generate a control voltage according to a reference current received from the outside; an amplifier connected to The controller and the amplifier are configured to receive the control voltage and provide a driving voltage to the load according to the received control voltage.

According to an exemplary embodiment, there is provided a gradient coil apparatus including: the driving unit as described above, connected to the outside, and configured to generate a driving voltage according to a reference current received from the outside; the gradient coil , connected to the driving unit, and configured to generate a gradient magnetic field according to a driving voltage received from the driving unit.

According to an exemplary embodiment, there is provided a magnetic resonance imaging apparatus, characterized in that the magnetic resonance imaging apparatus comprises the gradient coil arrangement as described above.

Other features and aspects will become apparent from the following detailed description, drawings, and claims.

Description of drawings

By describing the exemplary embodiment of the utility model in conjunction with the accompanying drawings, the utility model can be better understood, in the accompanying drawings:

FIG. 1 is a schematic block diagram illustrating a gradient coil device according to an exemplary embodiment;

2 is a schematic block diagram illustrating a controller according to an exemplary embodiment;

3 is a circuit diagram illustrating a feedforward unit according to an exemplary embodiment;

4 is an equivalent circuit diagram illustrating a gradient coil according to an exemplary embodiment;

FIG. 5 is a diagram illustrating waveforms according to an exemplary embodiment.

detailed description

Specific implementations of the present utility model will be described below, and it should be pointed out that in the specific description process of these implementations, in order to describe briefly and concisely, it is impossible for this specification to describe all the features of the actual implementations in detail. . It should be understood that, in the actual implementation process of any embodiment, just like in the process of any engineering project or design project, in order to achieve the developer's specific goals and to meet system-related or business-related constraints, Often a variety of specific decisions are made, and this can vary from one implementation to another. In addition, it is also understood that although such development efforts may be complex and lengthy, for those of ordinary skill in the art relevant to the disclosure of the present utility model, the disclosure disclosed in this disclosure Some design, manufacturing or production changes based on the technical content are just conventional technical means, and should not be understood as insufficient content of the present disclosure.

Unless otherwise defined, the technical terms or scientific terms used in the claims and the description shall have the ordinary meanings understood by those skilled in the technical field to which the present invention belongs. "First", "second" and similar words used in the utility model patent application specification and claims do not indicate any order, quantity or importance, but are only used to distinguish different components. "A" or "one" and similar words do not indicate a limitation of number, but mean that there is at least one. Words such as "comprises" or "comprises" and similar terms mean that the elements or items listed before "comprises" or "comprises" include the elements or items listed after "comprises" or "comprises" and their equivalent elements, and do not exclude other components or objects. "Connected" or "connected" and similar terms are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

FIG. 1 is a schematic block diagram illustrating a gradient coil device according to an exemplary embodiment.

As shown in FIG. 1 , a map coil device according to an exemplary embodiment may include a driving unit 100 and a gradient coil 300 .

The driving unit 100 may be connected to the outside to receive the reference current Iref from the outside. The driving unit 100 can generate the driving voltage Vd according to the reference current Iref.

In an exemplary embodiment, the driving unit 100 may include a controller 110 and an amplifier 130 .

The controller 110 may be connected to the outside to receive a reference current Iref from the outside. The controller 110 can generate the control voltage Vc according to the received reference current Iref.

The amplifier 130 may be connected to the controller 110 to receive the control voltage Vc. The amplifier 130 can provide the driving voltage Vd to the load (the gradient coil 300 ) according to the received control voltage Vc.

The gradient coil 300 may be connected to the driving unit 100 so as to receive a driving voltage generated by the driving unit 100 . The driving coil 300 may generate a gradient magnetic field according to the received driving voltage Vd.

The gradient coil apparatus according to the exemplary embodiment may be included in a magnetic resonance imaging apparatus for generating a gradient magnetic field required for magnetic resonance imaging.

FIG. 2 is a schematic block diagram illustrating the controller 110 according to an exemplary embodiment.

As shown in FIG. 2 , the controller 110 according to an exemplary embodiment may include a feedforward unit 111 , a feedback unit 113 and a control voltage generation unit 115 .

The feedforward unit 111 may be connected to the outside to receive the reference current Iref from the outside. The feedforward unit 111 can generate a feedforward voltage Vff according to the received reference current Iref. As will be described in detail below, the feedforward unit 111 may be composed of analog elements.

The feedback unit 113 may be connected to a load. Here, the load may be the gradient coil 300 . The feedback unit 113 may receive the load current Icoil flowing in the gradient coil 300 from the gradient coil 300 as a load. The feedback unit 113 can generate a feedback voltage Vfb according to the received load current Icoil.

In an exemplary embodiment, the feedback unit 113 may be a first adder S1 and a proportional-integral unit PI.

The first adder S1 can be connected to an external load. The first adder S1 may receive a reference current Iref and a load current Icoil, and may generate a first adder output according to the received reference current Iref and load current Icoil.

The proportional-integral unit PI may be connected to the first adder S1. The proportional-integral unit PI may receive the output of the first adder, and may generate the feedback voltage Vfb according to the output of the first adder.

The control voltage generation unit 115 may be connected to the feedforward unit 111 and the feedback unit 113 . The control voltage generating unit 115 can receive the feedforward voltage Vff and the feedback voltage Vfb, and can generate the control voltage Vc according to the received feedforward voltage Vff and the feedback voltage Vfb.

In an exemplary embodiment, the control voltage generation unit 115 may include a second adder S2 and a pulse width modulation unit PWM.

The second adder S2 may be connected to the feedforward unit 111 and the feedback unit 113 to receive the feedforward voltage Vff and the feedback voltage Vfb. The second adder S2 may generate a second adder output according to the received feedforward voltage Vff and feedback voltage Vfb.

The pulse width modulation unit PWM may be connected to the second adder S2 to receive the second adder output. The pulse width modulation unit PWM can generate a pulse width modulated control voltage Vc according to the output of the second adder.

FIG. 3 is a circuit diagram illustrating the feedforward unit 111 according to an exemplary embodiment.

As shown in FIG. 3 , the feedforward unit 111 may include analog elements such as resistors R1 - R4 , capacitors C1 - C4 , operational amplifiers P1 - P2 .

A first end of the first resistor R1 may be connected to the outside to receive a reference current Iref.

A first terminal of the first capacitor C1 may be connected to a first terminal of the first resistor R1, and a second terminal of the first capacitor C1 may be connected to a second terminal of the first resistor R1.

A first end of the second resistor R2 may be connected to a second end of the first resistor R1.

A first terminal of the second capacitor C2 may be connected to a first terminal of the second resistor R2, and a second terminal of the second capacitor C2 may be connected to a second terminal of the second resistor R2.

The negative input terminal of the first operational amplifier P1 can be connected to the second terminal of the first resistor R1, the positive input terminal of the first operational amplifier P1 can be connected to ground, and the output terminal of the first operational amplifier P1 can be connected to the second resistor R1. The second terminal of device R2.

A first terminal of the third resistor R3 may be connected to an output terminal of the first operational amplifier P1.

A first terminal of the third capacitor C3 may be connected to a first terminal of the third resistor R3, and a second terminal of the third capacitor C3 may be connected to a second terminal of the third resistor R3.

A first end of the fourth resistor R4 may be connected to a second end of the third resistor R3.

A first terminal of the fourth capacitor C4 may be connected to a first terminal of the fourth resistor R4, and a second terminal of the fourth capacitor C4 may be connected to a second terminal of the fourth resistor R4.

The negative input terminal of the second operational amplifier P2 can be connected to the second terminal of the third resistor R3, the positive input terminal of the second operational amplifier P2 can be connected to ground, and the output terminal of the second operational amplifier P2 can be connected to the fourth resistor R3. The second terminal of the device R4 and the control voltage generation unit 115 to provide the feedforward voltage Vff to the control voltage generation unit.

As described above, the feedforward unit 111 according to the exemplary embodiment may be composed of analog elements. Each element of the feedforward unit 111 will be described below with reference to FIG. 4 . Fig. 4 is an equivalent circuit diagram showing a gradient coil 300 according to an exemplary embodiment, and the parameters of each unit in such an equivalent circuit diagram can be obtained by curve fitting method according to the actually measured variation curve of coil impedance with frequency.

As shown in FIG. 4 , the gradient coil 300 can be equivalent to a circuit composed of four resistor units ( R1 , R2 , R3 , Rdc ) and four inductors L1 , L2 , L3 , Ldc.

Specifically, the first resistance unit (R1) is connected in series with the first inductance unit L1, the second resistance unit (R2) is connected in series with the second inductance unit L2, and the third resistance unit (R3) is connected in series with the third inductance unit L3 Connection, the first resistance unit (R1) and the first inductance unit L1, the second resistance unit (R2) and the second inductance unit L2, the third resistance unit (R3) and the third inductance unit L3 and the fourth inductance unit connected in series The units Ldc are connected in parallel, and then connected in series with the fourth resistance unit Rdc.

As such, the resistance values of the first to third resistors R1, R2, and R3 of the feedforward unit 111 according to the exemplary embodiment may be set equal to the first to third resistance units of the equivalent circuit diagram of the gradient coil 300, respectively. The resistance value of the resistance unit (R1, R2, R3). Therefore, the same reference numerals are used to denote the first to third resistors of the feedforward unit 111 and the first to third resistor units of the equivalent circuit diagram of the gradient coil 300 in this specification.

The variation of the impedance of the gradient coil 300 with frequency can be fitted by the following Lagrangian equation:

$\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}\mathrm{<span\; class="notranslate">\; ...</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

When the conditions are met: R ₃ >>R ₁₂ , L ₃ <<L ₁₂ , L ₁₂ <<1, formula (1) has the following corresponding relationship with Figure 4:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; ;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}\mathrm{<span\; class="notranslate">\; ...</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}\mathrm{<span\; class="notranslate">\; ...</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

in, $R_{12}=\frac{R_1\&CenterDot;R_2}{R_1+R_2};L_{12}=\frac{L_1\&CenterDot;L_2}{L_1+L_2}.$

Usually, the inductance of the coil used in the magnetic resonance equipment is less than 0.002H, so L ₁₂ <<1 is easily satisfied.

In the process of curve fitting to obtain the parameters in Figure 4, the limiting conditions R ₃ >>R ₁₂ , L ₃ <<L ₁₂ should be set so that formulas (2) and (3) are established. Since there are many adjustable parameters in FIG. 4 , the limiting conditions R ₃ >>R ₁₂ , L ₃ <<L ₁₂ are easily satisfied.

In order to use Figure 3 to realize the function of formula (1), the parameters of the external components of the operational amplifier in Figure 3 can be obtained from Figure 4. That is, the resistance values of the first resistor R1, the third resistor R3, and the fourth resistor R4 can be equal, namely:

R ₁ =R ₃ =R ₄

The resistance values of the first resistor R1 , the third resistor R3 and the fourth resistor R4 may range from several kΩ to tens of kΩ, for example, may be 10 kΩ.

The resistance value of the second resistor R2 may be:

R ₂ =R _a ·R ₁

The capacitance values of the first capacitor to the fourth capacitor C1, C2, C3, and C4 can be respectively:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; ;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}<span\; class="notranslate">\; ;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; .</span>$

FIG. 5 is a diagram illustrating waveforms according to an exemplary embodiment.

As shown in Figure 5, the feedforward unit 111 of the controller 110 is composed of analog components, so it is possible to perform analog signal conversion (Iref-Vff) only on the input reference current Iref as an analog signal to obtain the control voltage as an analog signal Vc, so as to realize the control of the amplifier 130 and further realize the control of the gradient coil 300 .

According to the exemplary embodiment, since the feedforward unit according to the exemplary embodiment does not include the A/D conversion unit and the D/A conversion unit, the delay caused by the feedforward unit is significantly reduced.

In addition, in the existing digital control method, the discrete equation that matches the digital sampling frequency is obtained after the equation (1) is z-transformed, and then the discrete equation is calculated by a digital circuit to obtain the Z in the equation (1) in real time ( s) value. This method requires the use of high-speed A/D, D/A conversion chips, complex discrete equation calculation chips and circuits, resulting in a large entire control unit that requires a separate controller. Such a controller controls the amplifier 130, so many wiring is required to achieve the control. The analog circuit according to the exemplary embodiment realizes the functions of the above-mentioned controller, and the analog circuit can be embedded in the amplifier circuit to be controlled, thereby omitting the control wiring between the two.

Compared with existing controllers implemented in the form of digital circuits, the cost of the analog feedforward unit according to the exemplary embodiment is lower.

Some exemplary embodiments have been described above. However, it should be understood that various modifications may be made. For example, if the described techniques are performed in a different order and/or if components in the described system, architecture, device, or circuit are combined in a different manner and/or are replaced or supplemented by additional components or their equivalents, then Suitable results can be achieved. Correspondingly, other implementations also fall within the protection scope of the claims.

Claims (8)

1. A controller, characterized in that the controller comprises: a feedforward unit connected to the outside, the feedforward unit is configured to receive a reference current from the outside, and generate a feedforward voltage according to the received reference current; a feedback unit connected to the load, the feedback unit is configured to receive a load current from the load, and generate a feedback voltage according to the received load current; a control voltage generating unit connected to the feedforward unit and the feedback unit, the control voltage generating unit is configured to receive the feedforward voltage and the feedback voltage, and generate the control voltage according to the received feedforward voltage and the feedback voltage, Among them, the feedforward unit is composed of analog components. 2. The controller according to claim 1, wherein the feedforward unit comprises: a first resistor, the first end of which is connected to the outside to receive a reference current; a first capacitor, the first end of the first capacitor is connected to the first end of the first resistor, and the second end of the first capacitor is connected to the second end of the first resistor; a second resistor, the first end of the second resistor is connected to the second end of the first resistor; a second capacitor, the first end of the second capacitor is connected to the first end of the second resistor, and the second end of the second capacitor is connected to the second end of the second resistor; a first operational amplifier, the negative input terminal of the first operational amplifier is connected to the second terminal of the first resistor, the positive input terminal of the first operational amplifier is connected to ground, and the output terminal of the first operational amplifier is connected to the second terminal of the second resistor second end; a third resistor, the first end of the third resistor is connected to the output end of the first operational amplifier; a third capacitor, the first end of the third capacitor is connected to the first end of the third resistor, and the second end of the third capacitor is connected to the second end of the third resistor; a fourth resistor, the first end of the fourth resistor is connected to the second end of the third resistor; a fourth capacitor, the first end of the fourth capacitor is connected to the first end of the fourth resistor, and the second end of the fourth capacitor is connected to the second end of the fourth resistor; The second operational amplifier, the negative input terminal of the second operational amplifier is connected to the second terminal of the third resistor, the positive input terminal of the second operational amplifier is connected to ground, and the output terminal of the second operational amplifier is connected to the second terminal of the fourth resistor The second terminal and the control voltage generating unit to provide the feedforward voltage to the control voltage generating unit. 3. The controller according to claim 2, wherein when the load is a gradient coil of a magnetic resonance imaging device, the gradient coil is equivalent to the first resistance unit to the fourth resistance unit and the first inductance unit to the first resistance unit A circuit composed of four inductance units, where, The first resistance unit is connected in series with the first inductance unit, the second resistance unit is connected in series with the second inductance unit, the third resistance unit is connected in series with the third inductance unit, the first resistance unit and the first inductance unit connected in series, The second resistance unit is connected in parallel with the second inductance unit, the third resistance unit is connected with the third inductance unit and the fourth inductance unit, and is connected in series with the fourth resistance unit; The equivalent circuit of the gradient coil can be fitted by the following Lagrangian equation, $\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}$ The first to fourth resistors and the first to fourth capacitors of the feedforward unit satisfy: R ₁ =R ₃ =R ₄ ; R ₂ =R _a ·R ₁ ; ${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ;</span>$ Wherein, R1 is the resistance value of the _first resistor and the first resistance unit, R2 is the resistance value of the _second resistor and the second resistance unit, _R3 is the resistance value of the third resistor and the third resistance unit, R4 is the resistance value of the _fourth resistor, _Rdc is the resistance value of the fourth resistor unit, _C1 is the capacitance value of the first capacitor, C2 is the capacitance value of the _second capacitor, and C3 is the capacitance of the _third capacitor value, C ₄ is the capacitance value of the fourth capacitor, L ₁ is the inductance value of the first inductance unit, L ₂ is the inductance value of the second inductance unit, L ₃ is the inductance value of the third inductance unit, L _dc is the inductance value of the fourth The inductance value of the inductor unit, and: ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ;</span>$ R ₃ >> R ₁₂ ; L ₃ << L ₁₂ ; L ₁₂ <<1. 4. The controller according to claim 1, wherein the feedback unit comprises: a first adder connected to the outside and the load, the first adder is configured to receive a reference current from the outside and a load current from the load, and generate a first adder output according to the received reference current and the load current; The proportional-integral unit is connected to the first adder, and the proportional-integral unit is configured to receive the output of the first adder and generate a feedback voltage according to the output of the first adder. 5. The controller according to claim 1, wherein the control voltage generating unit comprises: a second adder connected to the feedforward unit and the feedback unit, the second adder is configured to receive the feedforward voltage and the feedback voltage, and generate a second adder output according to the received feedforward voltage and the feedback voltage; A pulse width modulation unit connected to the second adder, the pulse width modulation unit is configured to receive the output of the second adder, and generate a pulse width modulated control voltage according to the output of the second adder. 6. A drive unit, characterized in that the drive unit comprises: The controller according to any one of claims 1 to 5, connected to the outside to generate a control voltage according to a reference current received from the outside; An amplifier is connected to the controller, and the amplifier is configured to receive the control voltage and provide a driving voltage to the load according to the received control voltage. 7. A gradient coil device, characterized in that the gradient coil device comprises: The drive unit according to claim 6, connected to the outside, and configured to generate a drive voltage according to a reference current received from the outside; The gradient coil is connected to the driving unit and configured to generate a gradient magnetic field according to a driving voltage received from the driving unit. 8. A magnetic resonance imaging device, characterized in that the magnetic resonance imaging device comprises the gradient coil device according to claim 7.