In frequency control system, of electric machinery fall fast and stop machine will come true through reducing frequency gradually, in the instant that frequency reduces, the synchronous rotate speed of electric machinery drops subsequently, and as a result of mechanical and inertial reason, the rotor rotate speed of electric machinery did not change. When synchronous rotate speed is less than rotor rotate speed, of rotor electric current phasic changed 180 degrees almost, electric machinery turns into from dynamoelectric condition generate electricity condition; Meanwhile, the torsion on electric machinery axis turned apply the brake into torsion, make the rotate speed of electric machinery drops quickly, electric machinery is in regenerative braking condition. Dc road feedbacks after commutate of Quan Bo of diode of follow on current of classics of electric energy of electric machinery reborn.

 

Because the electric energy of dc road cannot pass rectification bridge to pass on electrified wire netting, the capacitance that relies on transducer itself only is absorbed, although other part can waste electric energy, but the charge that capacitance still has short time piles up, form “ pump to rise voltage ” , make volts d.c. elevatory. Exorbitant volts d.c. will make each part parts of an apparatus is damaged.

 

Accordingly, be in to load generate electricity necessary step must be adopted to handle energy of this part second birth in condition of apply the brake. Handle the method of second birth energy: Apply the brake of specific power consumption and regenerative braking.

 

The working way of apply the brake of specific power consumption

The method that apply the brake of specific power consumption uses is component of discharge resistor unit is added in transducer dc side, waste second birth electric energy will realize apply the brake on power resistor. This is the directest way of energy of second birth of a kind of processing, it is second birth energy passes circuit of special apply the brake of specific power consumption to use up go up in resistor, translate into heat energy, because this is called again ” of “ resistor apply the brake, it includes unit of apply the brake and resistance of apply the brake 2 parts.

 

Unit of apply the brake

The function of unit of apply the brake is to become what the voltage Ud of dc loop sets more than to be restricted to be worth when (be like 660V or 710V) , put through bad news can circuit, after making dc loop passes resistor of apply the brake, with heat energy means releases energy. Apply the brake is unit but type of one’s duty buy and outside buy type 2 kinds, former it is the general transducer that applies to small-power, latter is apply to high-power transducer or be the operating mode that has special demand to apply the brake in. Tell from the principle, both does not have distinction, it is to regard as put through the “ switch ” of resistor of apply the brake, it includes comparator of sampling of power canal, voltage and drive circuit.

 

Resistor of apply the brake

Resistor of apply the brake is the carrier that is used at the second birth energy electric machinery to be used up with heat energy means, it includes resistor block value and power size two important parameter. Choose on the project normally more is moire resistor and aluminium alloy resistor two kinds: Former use exterior vertical ripple to be helpful for coming loose quantity of inductance of parasitism of hot bring down, choose expensive flame retardant and inorganic coating, silk of effective protection resistor not by ageing, prolong service life; Latter resistor weatherability, be able to bear or endure vibrational, resistor of framework of excel tradition porcelain, wide application is versed in badly at high demand accuse an environment to use, easy close together installation, easy add radiator, exterior is beautiful.

 

Process of apply the brake

The process of apply the brake of specific power consumption is as follows: A, decelerate falls in outside force action when electric machinery, when inverting (include to be procrastinated to move) , electric machinery namely with generating electricity condition moves, energy feedback answers dc loop, make bus voltage elevatory; When the B, position that reachs unit of apply the brake to leave when volts d.c. , the power canal of unit of apply the brake guides,

 

Electric current has shed resistor of apply the brake; Resistor of C, apply the brake uses up electric energy to be heat energy, the rotate speed of electric machinery is reduced, bus voltage also is reduced; Voltage drop of D, generatrix wants the cost that passes to unit of apply the brake, the power canal of unit of apply the brake ends, resistor of apply the brake has flowed without electric current; Voltage of generatrix of E, sampling is worth, unit of apply the brake repeats ON/OFF process, balance bus voltage, make the system moves normally.

 

Of unit of apply the brake and resistor of apply the brake anthology match

 

A, above all = of torsion of apply the brake of appraise cipher out ((electric machinery moment of inertia + the moment of inertia that electric machinery load measures convert to electric machinery) * (the speed before apply the brake – the speed after apply the brake) ) / 375* slowdown time – laden torsion

 

Usually, when having electric machinery apply the brake, electric machinery interior is put in certain loss, it is the 18%-22% left and right sides of rated torsion about, the result that gives because of this computation is in unit of apply the brake need not be received if be less than this limits;

 

The square that the B, block that follows resistance of computational apply the brake is worth voltage of movement of component of = apply the brake / (torsion of 0.1047*(apply the brake – 20% electric machinery are rated torsion) rotate speed of the electric machinery before * apply the brake)

 

In process of work of unit of apply the brake, of the voltage of dc generatrix litre fall depend on invariable RC, r is the block value of resistor of apply the brake namely, c electroanalysises for transducer interior the capacity of capacitance. Behavioral voltage is worth unit of apply the brake to be 710V commonly here.

 

The C, choice that has unit of apply the brake next

 

When the choice that has unit of apply the brake, the job of unit of apply the brake is the biggest the only basis that electric current is a choice, its computation formula is as follows:

 

Voltage of generatrix of dc of unit of apply the brake of = of value of restraint current instant is worth / resistance of apply the brake

 

Of resistor of apply the brake of D, final computation nominal power

 

Because resistor of apply the brake is short when duty, because of this character according to resistor and technical index, what we know resistor is nominal when power will be less than electrify consume power, can get with next type commonly:

 

Resistor of apply the brake is nominal resistor of power = apply the brake falls during apply the brake of frontal coefficient X use up utilization rate of power X apply the brake on average %

 

Characteristic of apply the brake

Apply the brake of specific power consumption (resistor apply the brake) the advantage is tectonic and simple, defect is moving loss of efficiency, will waste much energy when frequent apply the brake especially, and the capacity of resistor of apply the brake will increase.

 

How does the resistor of apply the brake that MM440 uses together have its effect

The attention answers when resistor of use apply the brake: Cycle of apply the brake chooses in P1237, should be P1240 setting 0 in order to to prohibit at the same time volts d.c. controller. Be sure to keep in mind! Otherwise, unit of apply the brake does not work, resistor of apply the brake is not so calorific also!

 

Regulator of voltage of use dc generatrix can rise to qualify the result with dc generatrix elevatory voltage, but it is with torsion of sacrificial apply the brake implementation, want so careful with.

 

Of resistor of apply the brake cycle of apply the brake basically is behead wave implement put through of the cooling time of time and resistor of apply the brake than, choosing what kind of cycle is not particularly important, the most important is the laden need according to you, it is burden or Qing Dynasty carry, the length of time of apply the brake will choose.

 

The power option that notable is resistor of apply the brake is not bigger better, must be less than the rated power of the transducer of 2.4 times, the zone that wants additionally to consider diode of follow on current carries ability.

 

The block value otherwise of resistor of apply the brake can be too small, meet otherwise burn down transducer, the smallest block that says inside use encyclopedia palpability allows is worth

 

Cycle of apply the brake, be electronic switch actually connect than. His connect comparing is fixed (after setting this parameter when you) , but length of time of actual apply the brake, not be fixed, change as operating mode of electric machinery apply the brake.

 

Perhaps 1S finishs apply the brake, perhaps 10S finishs apply the brake. The restraint current that this wants to see you accumulates the ability circumstance that discharges with unit of apply the brake and resistor of apply the brake to what dc generatrix charges, decide the process of apply the brake of unit of apply the brake.

 

The parameter setting of cycle of apply the brake is not main, main is to choose restraint current to be able to satisfy apply the brake to ask and make sure the dc generatrix voltage in process of apply the brake maintains relative stability to won’t continue to lift.

 

In other words, the design skill of apply the brake is, decide through what be worth to block of resistor of apply the brake and of power affirmatory, make sure process of apply the brake makes tension of transducer dc generatrix constant, and resistor not because of calorific and fast ageing. As to the parameter of cycle of apply the brake, set for 5% or 100% , I think is possible. It affects the transient process of apply the brake only, can not control result of final apply the brake.