A kind of resistor manufacture method and resistor

Technical field

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The present invention relates to a kind of resistor manufacture method and resistor, particularly relate to manufacture method and this resistor of the braking resistor of the dynamic braking being applied to electric armored vehicle.

Background technology

Electric armored vehicle adopts motor to drive, and motor has four-quadrant operation ability.When braking, drive motors can be converted to generator, and produce brake torque, be electric energy by part kinetic transformation while the reduction speed of a motor vehicle.At present, the braking energy consumption problem of electric armored vehicle, one adopts in two ways: one is charged a battery by rectification, another kind is by the consumption of braking dissipative cell, what dissipative cell then mainly adopted is braking resistor, when storage battery dump energy is sufficient, consume braking regenerative electric energy by braking resistor.The usual quality of armored vehicle is comparatively large, and brake torque during braking is much larger than common electric automobile, and braking regenerated energy is also larger, therefore has higher requirement to braking resistor.

In the engineering calculating method of service braking resistor resistance, when discharging current equals rated current one half, just can obtain the brake torque same with Rated motor torque phase, therefore the maximum of braking resistor is

wherein U is voltage during braking and rated voltage, and I is rated current.In order to ensure that electric machine controller is not damaged, the resistance value when electric current forcing restriction to flow through braking resistor is rated current is the minimum value of braking resistor

the range of choice of braking resistor resistance is generally

In the choosing method of above-mentioned braking resistor resistance, the restriction of the maximum current that the minimum resistance of braking resistor can bear by power device in electric machine controller cannot reduce further, seriously hinders the raising of braking energy consumption.In addition braking resistor is large power, electrically resistance element, one adopts wire coilings on ceramic skeleton such as constantan, copper-manganese or nickel Lip river alloy to form, the specific heat capacity of metal material is less, fusing point is low, and when braking energy is larger, the quality of braking resistor and volume all can increase.For Tank and Armoured Vehicle, due to vehicle body weight, need the energy of consumption large during braking, and the installing space of braking resistor is limited, adopts above-mentioned method for designing, cannot meet instructions for use.

Summary of the invention

For above-mentioned many technical problems existing in prior art, for realizing the braking energy consumption improving braking resistor further, and reducing resistor quality and volume, realizing according to R=ω L-R 0it is practical that brake resistance resistance is set, the invention provides a kind of manufacture method and resistor of braking resistor.

The manufacture method of above-mentioned resistor comprises:

A). cement, metal dust are mixed in proportion and stirs;

B). the described cement through stirring, metal dust being put into grinding machine and carrying out grinding, adding mould afterwards, from described both mold ends, two electrodes are inserted described mixture after grinding;

C). described mould is sealed, prevents from oxygen from entering making the described oxidization of metal powder in described mixture, cause conductance to reduce;

D). give described two electrifying electrodes by power supply, described mixture is made to produce heat, temperature is slowly increased to more than the fusing point of described metal dust (about 700 DEG C), and continues for some time until the described metal dust in described mixture all melts formation electroconductive cement;

E). treat described electroconductive cement cool to room temperature, the demoulding also seals preservation, forms braking resistor.

In a preferred embodiment of the invention, described metal dust is aluminium powder, and the quality of metal dust is the 5-10% accounting for gross mass.

In a preferred embodiment of the invention, if when using described resistor resistance and instructions for use inconsistent, change the cross-sectional area of described electroconductive cement or length by machine work thus change its resistance, making its resistance consistent with instructions for use.

In a preferred embodiment of the invention, resistor outer surface is wrapped up in the good insulating barrier of one deck thermal conductivity, as pottery, silica gel etc., namely prevent it from leaking electricity, there is again good heat-sinking capability.

The resistor that the present invention also provides a kind of manufacture method according to above-mentioned resistor to manufacture.

In a preferred embodiment of the invention, this resistor is used for new forms of energy car brake resistance, and resistance is configured to R=ω L-R 0, in formula, ω is rotor angular rate, and L is motor phase inductance, R 0for the internal resistance of motor stator winding.

According to the manufacturer of braking resistor of the present invention method is producedraw electroconductive cement, has higher specific heat capacity, energy is high temperature resistant, and can reduce resistance, the reduction volume of braking resistor, improves energy consumption.

No matter ordinary cement is be in humidity or drying regime, and (ordinary cement resistivity is in the dry state at 104-109 Ω m not possess good electric conductivity; Dampness is issued to 101-104 Ω m, and metallic conductor resistivity one 10 -7Ω m magnitude).After adding conducting medium in the present invention in ordinary cement layoutprocedure, make its resistivity meet corresponding requirement, its electric conductivity significantly promotes.Make ordinary cement not only keep original physicochemical property but also increase its electric conductivity according to the manufacture method of braking resistor of the present invention, become a kind of special composite material.

Metal dust is as conducting medium, and especially aluminium powder is as conducting medium, considers that the specific heat capacity of aluminium is high, and under same caloric value, conducting medium is that the temperature rise of the brake resistance of aluminium powder is less, can reduce the volume of brake resistance.Because braking resistor have employed new manufacture method and material, greatly reduce weight and the volume of braking resistor, the energy consumption consuming braking resistor can be improved to greatest extent, improve energy efficiency, enhance the reliability of system.

Accompanying drawing explanation

fig. 1for circuit when braking resistor works figure;

fig. 2for the manufacturing process of resistor figure;

Embodiment

The manufacture method of braking resistor comprises:

A). cement, aluminium powder are mixed in proportion and stirs;

B). the cement through stirring, aluminium powder being put into grinding machine and carrying out grinding, adding mould afterwards, from both mold ends, two electrodes are inserted the mixture after grinding;

C). mould is sealed, prevents from oxygen from entering making the aluminium powder oxidation in mixture, cause conductance to reduce;

D). give two electrifying electrodes by power supply, make mixture produce heat, temperature is slowly increased to more than the fusing point of aluminium powder (about 700 DEG C), and continues for some time until the aluminium powder in mixture all melts formation electroconductive cement;

E). treat electroconductive cement cool to room temperature, the demoulding also seals preservation, forms braking resistor.

The quality of aluminium powder may be selected to be the 5-10% accounting for gross mass.If when using actual, braking resistor resistance is inconsistent with instructions for use, changes its resistance by the cross-sectional area of machine work change electroconductive cement or length, makes its resistance consistent with instructions for use.Also braking resistor outer surface can be wrapped up in the good insulating barrier of one deck thermal conductivity, as pottery, silica gel etc., namely prevent it from leaking electricity, there is again good heat-sinking capability.

The resistor that the present invention also provides a kind of manufacture method according to above-mentioned resistor to manufacture.This resistor is used for new-energy automobile braking.

When vehicle traveling carries out retarding braking, machine operation is at the second quadrant, and output torque becomes braking force from actuating force.Now generating voltage drops on motor internal resistance, braking resistor and motor inductances completely, will produce a transient high-current in the stator windings.The reactance that now three phase electric machine is single-phase

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in formula, ω is rotor angular rate, and L is motor phase inductance, R 0for the internal resistance of motor stator winding, R is the resistance of braking resistor.Work as R+R 0during=ω L, the energy that braking resistor consumes is maximum, therefore the resistance of braking resistor is chosen for R=ω L-R 0time, best energy consumption effect can be reached in theory.Under this resistance, existing braking resistor can produce a large amount of heat energy when braking and consuming energy, and cannot meet this demand of dispelling the heat in a large number, thus due to the restriction of the performance and used life of existing braking resistor, cannot adopt R=ω L-R at present in actual use 0resistance arrange, based on the consideration of performance and used life aspect, can only then adopt engineering calculating method relatively reliably.But utilize the brake resistance that resistance manufacture method of the present invention makes, adopt R=ω L-R 0resistance can meet heat radiation and requirements for life when arranging completely.

The phase resistance of electric armored vehicle drive motors is 0.06 Ω in one embodiment, and phase inductance is 0.176mH.The max. speed of auto in Braking is 120km/h, and the rotor speed of motor is rpm, and rotor electric angle frequency is 600Hz, and the effective value of motor lines back-emf is V, and braking resistor resistance is 0.6 ohm.The maximum current effective value flow through in circuit during braking is 420A, and the gross power that braking resistor consumes is 530kW.As accompanying drawing 1shown in, e a, e b, e cfor the back-emf that motor during dynamic braking produces on ABC three-phase, R 0a, R 0b, R 0cbe respectively the resistance of each phase winding of motor stator, L a, L b, L cbe respectively each phase inductance of stator, R a, R b, R cfor the braking resistor of each phase.

The total weight of electric armored vehicle is 20 tons, brakes parking from max. speed, and whole kinetic energy of vehicle are about kJ, supposes that this kinetic energy all will be converted into heat energy.Under the prerequisite ignoring motor body heating, can suppose that this part energy is all absorbed by braking resistor.The material of this braking resistor is electroconductive cement, and specific heat capacity is 0.78kJ/ (kgC), and weight is 23.7kg, and during dynamic braking, temperature rise is 600 DEG C.

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Module 2.0

Resistor Construction

What you´ll learn in Module 2.0

• After studying this section, you should be able to:
• &#; Describe common types of resistor construction.
• Surface Mount Technology(SMT).
• Carbon Film Resistors.
• Carbon Composition Resistor.
• Wire-wound resistors.
• Metal film resistors.
• Thermal Fuse Resistors

Fixed Resistors

Fig 2.0.1 Resistor Symbols

Resistors are components used to resist the flow of electric current and have a stated value of RESISTANCE. Many types of resistors are used having different uses and construction. The most common types have a fixed value of resistance so are often called fixed resistors. They are shown on circuit schematic diagrams (theoretical diagrams that show how the circuit components are connected electrically, rather than what a circuit looks like physically) using one of the symbols shown in Fig 2.0.1.

Various types of fixed resistors are used in circuits, they are the most numerous of all electronic components and their most common job is to reduce voltages and currents around a circuit so that &#;active components&#;, transistors and integrated circuits for example, that carry out tasks such as producing or amplifying signals within the circuit are supplied with the correct voltages and currents to work properly.

Resistors are also used in conjunction with other components such as inductors and capacitors to process signals in many ways.

Because resistors are &#;passive components&#; they cannot amplify or increase voltages currents or signals, they can only reduce them. Nevertheless they are a most essential part of any electronic circuit.

Fig 2.0.2 Fixed Resistor Types

SMT (Surface Mount Technology)

Many modern circuits use SMT resistors. Their manufacture involves depositing a film of resistive material such as tin oxide on a tiny ceramic chip. The edges of the resistor are then accurately ground, or cut with a laser to give a precise resistance (which depends on the width of the resistor film), across the ends of the device. Tolerances may be as low as ±0.02%. Contacts at each end are soldered directly onto the conductive print on the circuit board, usually by automatic assembly methods. SMT resistors normally have a very low power dissipation. Their main advantage is that very high component density can be achieved.

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Carbon Film Resistors

Similar construction to Metal film resistors but generally with wider tolerance (typically +/- 5%), shown in Fig. 2.0.2 mounted on paper strips for machine insertion into printed circuit boards. Small resistors are extremely inexpensive components and are also often sold in batches of 10s or 100s in this form for easier handling.

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Carbon Composition Resistor

Carbon composition is the oldest design and usually the cheapest of the resistors. Carbon granules are mixed with a filler material and inserted into a tubular casing. In earlier types vulcanised rubber was used but in modern designs the carbon is mixed with a ceramic filler. The value of resistance is determined by the amount of carbon added to the filler mixture. Carbon composition resistors do not have the close tolerances of either carbon or metal film types. Typical tolerances are +/-10% or 20%. One advantage however is that they are better suited to applications involving large voltage pulses than the more modern types.

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1Watt resistor

Carbon composition, carbon and metal film resistors are available in a range of power ratings, from 0.125W to 5W. In a resistor, the power that the resistor must dissipate (get rid of as heat) depends on the voltage difference (V) across the resistor, and the current (I) flowing through it. These are multiplied together to obtain the amount of power (P) that must be dissipated using the formula P = IV. For any particular type or value of resistor, the greater the power rating, the larger the physical size of the resistor.

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Wire-wound resistors

Wirewound resistors are very variable in construction and physical appearance. Their resistive elements are commonly lengths of wire, usually an alloy such as Nichrome (Nickel/Chromium) or Manganin (Copper/Nickel/Manganese) wrapped around a ceramic or glass fibre rod or tube and coated in an insulating flameproof cement film. They are normally available in quite low values of resistance (single ohms to a few Kilohms) but can dissipate large amounts of power. In use they may get very hot.

For this reason high power wirewound resistors may be housed in a finned metal case that can be bolted to a metal chassis to dissipate the heat generated as effectively as possible. With all types of wirewound resistor, fire protection is important and flame proof cases or coatings are vital. Lead-out wires are normally welded rather than soldered to the resistor.

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Metal film resistors.

These resistors are made from small rods of ceramic coated with metal such as a nickel alloy or a metal oxide such as tin oxide. The value of resistance is controlled firstly by the thickness of the coating layer; the thicker the layer, the lower the value of resistance. Also by a fine spiral groove cut along the rod using a laser or diamond cutter to cut the carbon or metal coating effectively into a long spiral strip, which forms the resistor. Metal film resistors can be obtained in a wide range of resistance values from a few Ohms to tens of millions of Ohms with a very small TOLERANCE. For example a typical value might be 100KΩ ±1% or less i.e. for a stated value of 100KΩ the actual value will be between 99KΩ and 101KΩ. Note that although the body colour (the colour of the laquer coating) on metal film resistors is often grey, this is not a reliable guide. Small carbon, metal and oxide resistors may be made in various body colours such as dark red, brown, blue, green, grey, cream or white.

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5 Watt Wirewound Resistor

A wirewound resistor can have a smaller physical size for a given power rating than carbon composition or film resistors, compare this 5W resistor with the 1W resistor (labelled 3 in Fig.2.0.2). Wirewound resistors however, do not not have the close tolerance of composition or film types. This 4R7 resistor has a tolerance of ±10%.

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PCB Mounting Wirewound Resistor

Wirewound resistors usually have a resistance range from around 1Ω to about 50KΩ. Because they use a coil of wire as their resistive element they tend to act as inductors to some degree. This limits their use to low frequency circuits up to around a few tens of kiloHertz (kHz). This example, available in power ratings up to 25W, is for mounting on a printed circuit board and to prevent heat damage to the board, the specially shaped legs ensure an air gap between the resistor and the board. The whole resistor is enclosed in a flameproof ceramic layer.

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High Power Metal Film

Metal film resistors are also available in high power types with power ratings less than wirewound types (typically less than 5W) but having closer tolerances.

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Fusible Wirewound Resistor

In this fusible resistor, the current flowing through the resistor first flows through a spring loaded connection that is positioned close to the body of the resistor. The heat generated by the wirewound resistor under normal conditions would not be sufficient to melt the blob of solder holding a spring wire in place. If too much current flows through the resistor it overheats, the solder melts and the wire springs up, opening the connection and stopping the current. This then requires a service technician to find the cause of the over-current before re-soldering the spring connection to restore normal operation. It is important to use the correct type of solder (usually stated in the service manual for the equipment) when re-soldering, since this will affect the temperature at which the spring opens.

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