CN1274086A - Both AC and DC detecting and control device with giant magnetoelectric resistance effect - Google Patents

Abstract

A giant magnetoresistance effect AC and DC dual-purpose current detection and control device, which is internally composed of a giant magnetoresistance effect sensor head, a coupling magnetic circuit component, an amplifier comparator, and a power amplifier. The sensing head can be made of unbalanced four-arm electric bridge and balanced four-arm electric bridge by giant magnetoresistance material, and the sensitive resistors on the bridge arms are made on the same substrate. The device can output analog signals and logic signals at the same time, and has a large driving load capacity. The device can also be used as magnetic field detection and control devices, such as magnetic control switches, AC and DC current relays, transmitters, phase loss protectors, position, rotation angle, speed, rotational speed measurement and control devices and instruments.

Description

Giant magnetoresistance effect AC and DC dual-purpose current detection and control devices

The invention relates to an AC and DC dual-purpose current detection and control device, in particular to a current detection and control device made of a giant magnetoresistance material as a sensing head.

Usually magnetoresistance refers to the change of material resistivity caused by the magnetic field, quantitatively expressed as MR=[ρ(H)-ρ(0)]/ρ×100%, where ρ can be ρ(0) or ρ(H) , the definition of ρ(H) is adopted in this patent specification. For ferromagnets, the maximum MR is 3-5% and the anisotropy is called anisotropy magnetoresistance (AMR for short).

In 1988, it was observed that the magnetoresistance of (Fe/Cr) metal multilayer film can reach 200%, which is called the giant magnetoresistance effect (Giant magnetoresistance abbreviated as GMR).

After 1992, it was found that the GMR in some non-miscible alloy particle films reached 60% at low temperature. In 1996, it was found that the magnetoresistance of Fe/HfO 2 /Co tunnel junction reached 31% (TMR) at 30K. In recent years, it has been found that the MR of rare earth manganese oxides doped with alkaline earth metals can reach 10 ³ -10 ⁶ %, which is called Colossal Magnetoresistance (CMR for short).

Due to its obvious application prospects, the giant magnetoresistance effect has been paid attention to in both academia and industry. It has been used to make high-density magnetic recording readout heads, random access memories, etc., but the successful application of the giant magnetoresistance effect It has not been reported internationally.

The purpose of the present invention is to provide a current detection and control device made of giant magnetoresistance effect, especially to provide a dual-purpose AC and DC device, which has no electrical contact with the main circuit, is easy to use, has a large detection current range, and works Wide frequency range, current detection and control devices that are not damaged by over-range.

The object of the present invention is achieved like this: a kind of electric current detection, control device, it is characterized in that sensing head is made unbalanced four-arm electric bridge or four-lead resistance or balance four-arm electric bridge by giant magnetoresistance material, adds coupling Magnetic circuit components, amplifiers, comparators, and power amplifiers are made into one device. The device is close to the current-carrying conductor or the current-carrying conductor passes through the coupling magnetic conduction ring, and the magnetic field generated by the current causes the state of the four-arm bridge or the change of the resistance of the four leads, thereby detecting the magnitude of the current or performing a control operation. The sensitive resistor of the bridge sensor head is fabricated on a substrate.

The characteristics of the present invention are: providing a sensitive and reliable current detection and control device without any electrical contact with the main circuit, with a large detection current range, a wide operating frequency range, and never being damaged if the range is exceeded. The device can work as soon as it is close to the main circuit, and it is very convenient and flexible to be used in high-current applications. Especially when upgrading the original equipment technology, the workload and cost of the main circuit transformation are greatly reduced.

The device of the invention is fully sealed, solid, has no contact, no mechanical action parts, impact resistance, corrosion resistance, radiation resistance, explosion-proof, good thermal stability, and can be used in various occasions with harsh environments.

The output signal of the device of the present invention can have analog signal, logic signal and control driving signal at the same time, and the output level can be easily matched with various automatic control systems and computer systems. Compared with traditional current detection and control devices, the device has a solid and simple structure, is convenient to use, saves a lot of metal materials, has low cost, high cost performance, and is easy to promote. The characteristics are especially obvious for applications with small current (as small as 150mA) and high current (thousands of amperes). If it is made into a current relay, its action time is much shorter than that of a traditional current relay.

The device of the present invention can be derived into devices with multiple uses, such as a three-phase motor phase loss protector, a current signal transmitter and instrument, and various relay protection devices.

Another feature of the present invention is: the current detection and control device can be used as a magnetic field detection and control device; it can be used as a high-speed magnetic control switch, position, rotation angle, speed, and rotational speed measurement and control device.

The present invention will be further described below in conjunction with the accompanying drawings and examples.

Fig. 1 is the schematic diagram of the unbalanced bridge made of giant magnetoresistance material for the sensing head of the device of the present invention

Fig. 2 is the schematic diagram of the sensor head of the device of the present invention made of four-lead resistors made of giant magnetoresistance materials

Fig. 3 is the schematic diagram of the balance bridge made of giant magnetoresistance material for the sensor head of the device of the present invention

As shown in the figure, the sensor head of the device of the present invention can be selected from giant magnetoresistance materials such as alloy films, metal multilayer films, and metal particle films, and can also select giant magnetoresistance effect materials such as CN96117043. Sensitive resistors in the bridge-type sensing head are prepared on one substrate. The sensing head is integrated with the electronic circuit and coupled magnetic circuit components.

The device of the present invention has two forms with a coupling magnetic conduction ring and without a magnetic conduction ring. Devices without magnetic rings only need to be close to current-carrying conductors to work. This method of use is especially suitable for small current or extra large current occasions. Especially for some small current measurement and control, it can completely not affect the work of the main circuit.

For a device with a coupled magnetic ring, the current-carrying conductor only needs to pass through the magnetic ring, and the magnetic ring has movable openings that can be conveniently clamped on the conductor without changing the original current-carrying conductor.

Figure 1 shows an unbalanced four-arm bridge as a sensing head, in which the sensitive resistor is made on a substrate with a giant magnetoresistance material. Once the magnitude of the current to be measured changes or the magnetic field to be measured changes, the state of the unbalanced bridge will change, and the bridge will cross the At the balance point, the comparator integrated with the bridge flips and outputs the switch signal. The device is so small that it is only the size of a thumbnail and can drive a 500mA load.

Figure 2 is a four-lead resistor made of giant magnetoresistance material. A constant current source is provided inside the device. The instrumentation amplifier in the device is connected to the voltage detection terminal of the four-lead resistor. When the current to be measured changes or the external magnetic field changes, the giant magnetoresistance The resistance value of the material four-lead resistance changes, and the current or magnetic field increases, the resistance value becomes smaller, the output voltage difference of the voltage detection terminal decreases, the analog signal is amplified by the instrument amplifier, and then the comparator and the power amplifier respectively output logic signals and control signals. Signal. The feature of this device is that when the current to be measured is zero or the external magnetic field is zero, the output amplitude of the instrumentation amplifier is large, and the output amplitude of the instrumentation amplifier decreases when the current or magnetic field to be measured increases, so that the linear region of the instrumentation amplifier can be well utilized to ensure linearity of the entire device.

Fig. 3 shows that the sensor head of the device of the present invention is made of a giant magnetoresistance material to balance the four-arm bridge, and the sensitive resistor is made on a substrate. When the current or magnetic field to be measured changes, the bridge is unbalanced, and the output signal of the bridge is amplified, and the device outputs an analog signal, and outputs a logic signal and a control signal respectively after passing through a comparator and a power amplifier.

Claims (6)

1. the dual-purpose current detecting of AC and DC, control device is characterized in that adopting giant magnetic resistor material to make sensing head, with amplifier, comparer, output power amplifier, integrally combine and make a device.

2. by the described current detecting of claim 1, control device, it is characterized in that having two types, a kind of is directly to press close to current use type, and another kind is that current passes magnetic guiding loop, and magnetic guiding loop is jagged, and indentation, there is placed the giant magnetoresistance sensing head; Magnetic guiding loop, giant magnetoresistance sensing head, amplifier, comparer, output power amplifier integrally combine, and become a device.

3. by right 1,2 described current detecting, control device, it is characterized in that sensing head makes uneven four arm electrical bridge with giant magnetic resistor material, two diagonal angle resistance of electric bridge are directly cut apart on the magnetic resistance material sheet and are made, the output terminal of unbalanced bridge directly is connected with comparer, makes to have the device that output driving load capacity is not less than 500mA.

4. by right 1,2 described current detecting, control device, it is characterized in that sensing head is 4 lead resistances that giant magnetic resistor material is made, the voltage detecting termination instrument amplifier of four lead resistances, add comparer, power amplifier is made and can be exported simulating signal simultaneously, logical signal, the device of drive control signal.

5. by claim 1,2 described current detecting, control device, it is characterized in that sensing head makes the balance four arm electrical bridge by giant magnetic resistor material, the brachium pontis sensitive resistance is directly made on a substrate, electric bridge and amplifier, comparer, power amplification is in conjunction with making the device of exporting simulating signal, logical signal and drive control signal simultaneously.

6. by claim 1, derivative other device of 2 described current detecting control devices, as overcurrent, undercurrent current transducer, current relay, open-phase protector for three-phase motor, silicon controlled rectifier protecting device, brushless electric machine, magnetic switch, position, tarnsition velocity, tachometric survey control device and instrument.

Images