Optimization control circuit for MR permanent magnet heating
By introducing a delay relay into the MR permanent magnet heating control circuit, delayed heating is solved, and the fuse blowing problem caused by excessive current at low temperatures is improved, and the system safety and heating efficiency are improved.
Patent Information
- Application Number
- CN202421024154.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-13
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2034-05-13
AI Technical Summary
In low temperature environments, the initial resistance of the MR permanent magnet is low when heated, resulting in excessive current during startup, which can easily lead to fuse blown and system safety problems.
A MR permanent magnet heating control circuit including a delay relay is designed to delay heating in the initial state of power-on, so as to avoid excessive peak current.
It effectively reduces the peak current at startup, improves system safety, and does not affect subsequent heating efficiency.
Smart Images
Figure CN222302031U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of permanent magnet magnetic resonance, in particular to an optimized control circuit for heating an MR permanent magnet. Background Art
[0002] In order to ensure clear imaging of the magnetic resonance system, the magnetic field needs to have strong stability. For low-field permanent magnet magnetic resonance systems, the temperature of the magnet has a strong influence on the field strength and uniformity of the magnetic field, and is a key factor affecting the stability of the system. Therefore, it is very important to control the temperature of the permanent magnet. Usually, the temperature control of the permanent magnet is carried out by heating, but the resistance of the heating belt has a direct impact on the current. Under low temperature conditions, the resistance of the heating belt can be as low as 10Ω, and after heating, the temperature rises, and the maximum can reach about 30Ω. Therefore, when using alternating current to heat the upper and lower magnets at the same time, the instantaneous maximum current can reach 44A. The starting current is too large, and the fuse is prone to blowing, which affects the safety of the entire system.
[0003] At present, some solutions are to connect capacitors in series in the heating circuit and use the capacitive reactance of the capacitor to limit the current. However, due to the existence of capacitor ESR (equivalent series resistance of the capacitor), it will generate a certain amount of heat in the circuit, and the degree of heat varies with the size of the capacitor ESR. Secondly, the series capacitor will also have a certain current limiting effect under normal working conditions (not the initial startup state), which will have a negative impact on the overall heating efficiency and time.
[0004] In view of the problem that the initial resistance of the heating belt of the permanent magnet in the magnetic resonance system is low when it is in a low temperature environment, the maximum current of a single circuit can reach 22A during AC heating, and the maximum current of a dual circuit can reach 44A, resulting in the initial heating current being too large. It is urgent to provide a new type of MR permanent magnet heating optimization control circuit to solve the above problem. Utility Model Content
[0005] The technical problem to be solved by the utility model is to provide an optimized control circuit for MR permanent magnet heating, which can reduce the peak starting current, solve the problem that the fuse is easily burned due to excessive current when the heating belt is started, and ensure the safety of the system.
[0006] In order to solve the above technical problems, a technical solution adopted by the utility model is: to provide an optimized control circuit for MR permanent magnet heating, including two heating belt control circuits for MR permanent magnet heating, the heating belt control circuit including a heating belt, a temperature controller, and a relay connected to the heating belt, the input end of the temperature controller is connected to the temperature sensor on the heating belt, and the output end is connected to the relay through a control line, in one of the heating belt control circuits, a delay relay is arranged on the control line connecting the temperature controller and the relay, which is used to delay the start of heating of the heating belt in the initial state of power-on.
[0007] In a preferred embodiment of the present invention, the input end of the temperature controller detects the temperature of the MR permanent magnet on the heating belt through a temperature sensor.
[0008] In a preferred embodiment of the present invention, the time delay relay is an Omron time delay relay H3Y-4C.
[0009] The beneficial effects of the utility model are as follows: the utility model has the advantages of simple circuit, high reliability, and no influence on subsequent heating efficiency after the startup is completed. By adopting the time-sharing starting mode of the time delay relay, the problem of low resistance of the heating belt at low temperature and large peak current at startup can be effectively solved. Excessive peak current often affects the safety of the system, such as triggering the current protector, fuse blowing, line overheating and fire, etc. The time-sharing starting of the two heating belts of the magnet through the time delay relay can effectively reduce the peak current at startup and greatly improve the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 The utility model discloses a circuit diagram of an optimized control circuit for heating an MR permanent magnet. DETAILED DESCRIPTION
[0011] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.
[0012] See also Figure 1 , the utility model embodiment includes:
[0013] An optimized control circuit for heating an MR permanent magnet comprises two heating belt control circuits for heating the MR permanent magnet, wherein the heating belt control circuit comprises a heating belt, a temperature controller, and a relay connected to the heating belt, wherein the input end of the temperature controller is connected to a temperature sensor on the heating belt, and the output end is connected to the relay via a control line, and in one of the heating belt control circuits, a delay relay is arranged on the control line connecting the temperature controller and the relay, so as to delay the start of heating of the heating belt in the initial state of power-on.
[0014] There are two heating controls in the control process. Delaying the start of one of them at startup can avoid the problem of excessive peak current. The specific control scheme is as follows: Figure 1As shown, the thermostat detects the temperature of the magnet on the heating belt through the pt100 temperature sensor (metal platinum resistance temperature sensor, its resistance is 100Ω at 0℃, the higher the temperature, the greater the resistance), and controls the relay heating through the control line. Due to the existence of the delay relay, in the initial state of power-on, one heating belt shown in the figure will be delayed to start. Before the delay relay is closed, the thermostat has no control effect on the heating belt, and the heating belt does not heat up. After the delay relay is closed, the other heating belt has completed preheating and the current has dropped to the normal range. At this time, the delay relay timing ends, the switch is closed, and the thermostat control line works again to achieve the purpose of time-sharing start and reducing the peak current.
[0015] Since the time delay relay is set on the control line, the current required for controlling the power-on is low, and there is no need to select a large current relay. Therefore, the preferred solution is to use the Omron time delay relay H3Y-4C, which can reduce the size and cost of the time delay relay.
[0016] It should be noted that the control method of this optimized control circuit only works at the initial startup and does not control the current in real time, so it does not affect the subsequent magnet temperature control link.
[0017] The utility model mainly proposes a solution circuit for the problem that the initial heating current of the permanent magnet in the magnetic resonance system is too large at low temperature. By adding a delay relay on the temperature controller control line, the two heating belts are started in time, which effectively reduces the peak current at the time of starting without affecting the subsequent heating efficiency. The utility model solves the system safety problems such as the fuse burning due to the excessive peak current at the start, and has the advantages of simple circuit, high reliability, and no influence on the subsequent heating efficiency after the start is completed.
[0018] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. An optimized control circuit for MR permanent magnet heating, comprising two heating belt control circuits for MR permanent magnet heating, wherein the heating belt control circuit comprises a heating belt, a temperature controller, and a relay connected to the heating belt, wherein the input end of the temperature controller is connected to a temperature sensor on the heating belt, and the output end is connected to the relay through a control line, wherein: In one of the heating belt control circuits, a delay relay is arranged on the control line connecting the temperature controller and the relay, so as to delay the start of heating of the heating belt in the initial state of power-on.
2. The optimized control circuit for MR permanent magnet heating according to claim 1, characterized in that: The input end of the temperature controller detects the temperature of the MR permanent magnet on the heating belt through a temperature sensor.
3. The optimized control circuit for MR permanent magnet heating according to claim 1, characterized in that: The time delay relay adopts Omron time delay relay H3Y-4C.