CN104143821A - Regenerative bleeder resistor protection method - Google Patents

Abstract

The invention discloses a regenerative bleeder resistor protection method. The method includes the steps that a bleeder resistance value according with work conditions is sorted out through calculation checking; a bleeder resistor is connected with a system, and the regenerative bleeder resistor is initialized through a variable by setting driver parameters for protection; a driver executes and processes regenerative brake logic, whether an alarm is sounded is judged, and accordingly the bleeder resistor is replaced by a regenerative bleeder resistor meeting requirements. If bus overcurrent occurs, a program is interrupted. By means of the method, the bleeder resistor can be protected, hardware damage is prevented, and it is guaranteed that the system operates safely and stably.

Description

A kind of guard method of the bleeder resistance of regenerating

Technical field

This law invention relates to a kind of method of protecting regeneration bleeder resistance, solves regeneration bleeder resistance protection question, belongs to power electronics category.

Background technology

Bleeder resistance is widely used in field of power electronics with its simple and practical advantage such as cheap.In drive and control of electric machine, the energy storage of bus capacitor is limited, if do not controlled, can not surpass the perhaps maximum withstand voltage of power device of direct current, thereby cause hardware damage, the effect that charges and discharge electric capacity is played in bleeder resistance compensation in system, so bleeder resistance plays very important effect to system safety steady operation.Selection does not meet the bleeder resistance of operating mode, can cause the abnormal of regeneration dynamic braking, but the accurate system of selection of bleeder resistance is failed to provide in existing article.

Summary of the invention

Goal of the invention: object of the present invention provides a kind of method of protecting charging bleeder resistance.During according to operation, the energy conversion relation of servo-driver or frequency convertor system, power constraint condition, minimum resistance constraint, select the bleeder resistance that meets operating mode, by the operation of bleeder resistance connecting system, thereby reaches system optimal.

Technical scheme: the present invention is achieved through the following technical solutions:

A method of protecting regeneration bleeder resistance, comprises the steps:

1) by calculating, check, select the vent discharge resistance that meets operating mode;

2), by bleeder resistance connecting system, system judges Set For Current state;

3) regenerative braking logic is processed in driver operation, and whether the regeneration bleeder resistance of judgement access meets the requirements;

4) if there is bus current overcurrent, interrupt routine is with protection bleeder resistance.

The step of selecting the vent discharge resistance that meets operating mode in step 1 is as follows:

1) by law of conservation of energy, judge whether system needs bleeder resistance.

2) by power constraint condition, determine the specification of bleeder resistance.

3) determine the minimum resistance of bleeder resistance.

Whether system needs bleeder resistance specifically to comprise the steps:

1) the regenerated energy E of computing system _mwith the absorbable ENERGY E of bus filter capacitor _csize,

2) compare E _mwith E _csize, system is in unit situation, if E _m<E _c, do not need bleeder resistance, otherwise need; If system is in common bus situation do not need, otherwise need bleeder resistance; Work as E _mjduring <0, people is for being forced to 0 summation;

In step 1, $E_m=\frac{1}{2}(J_m+J_l){{\mathrm{\&omega;}}_m}^2-{{3I}_m}^2\frac{R_m}{2}{t}_d-\frac{1}{2}{T}_f{\mathrm{\&omega;}}_m{t}_d+E_{\mathrm{\&Delta;f}},$

$E_c=\frac{1}{2}C({U_{\max }}^2-{U_{\mathrm{nom}}}^2),$

J _mfor motor self rotor moment of inertia, J _lfor mechanical load is folded to the moment of inertia of motor shaft end, ω _mfor the angular speed before decelerating through motor, I _mfor the phase current effective value of motor between deceleration period, R _mfor line resistance between motor phase, t _dfor the time of slowing down, the s of unit, T _ffor friction torque, E _{△ f}for the potential variation amount in Braking system process, potential energy increases then symbol for negative, and decrease of potential energy is being for just, E _cfor the absorbable energy of bus filter capacitor, C is driver bus filter capacitor, U _maxfor the accessible maximum voltage of bus before releasing, i.e. discharge voltage, U _nomfor bus average voltage, u _llline voltage for rectification input.

The specification of determining bleeder resistance comprises the steps:

1) calculate the peak-pulse power P releasing _{max_regen}, maximum regeneration power P _max, average power P _av;

2) according to formula P _max<P _{max_regen}with determine bleeder resistance R _bmaximum;

3) calculate the minimum value of bleeder resistance;

4) according to actual condition, determine the rated power of bleeder resistance;

Wherein, $P_{\max \_\mathrm{regen}}=\frac{{U_b}^2}{R_b},$ $P_{\max }=\sqrt{3}{\mathrm{EMF}}_b{I}_m,$ $P_{\mathrm{av}}=\frac{E_m-E_c}{t_{\mathrm{cycle}}},$ $R_{b\min }=\frac{U_{\mathrm{ov}}}{I_{\mathrm{bc}}},$

U _bfor the bus point voltage of releasing, P _maxissuable maximum regeneration power during for motor braking, I _mfor the phase current effective value of motor between deceleration period, EMF _bfor removing the winding back emf of loss part reduced voltage, k _bfor winding back emf constant, i.e. the 1000rpm back-emf effective value that rolls off the production line, n is the rotating speed that motor is moving before slowing down, EMF _bfor removing the winding back emf of loss part reduced voltage, t _cyclefor the one-period of motor cycle operation, deceleration time and non-deceleration time sum, U _ovfor bus overvoltage point voltage I _bcthe direct current that can move continuously when radiator is 80 ℃ for bleeder pipe.

In step 4, rated power determining step is as follows:

1) when system is used the built-in regeneration bleeder resistance bleeder resistance of maybe need not regenerating, during entirely by capacitive absorption, the rated power of bleeder resistance is 50% of built-in resistor rated power;

2), when using external regeneration bleeder resistance, driver judges whether the resistance of user's input is less than the function of regeneration bleeder resistance minimum value, if the minimum value of being less than needs to change external bleeder resistance; If be greater than, judge whether external cold wind equipment;

4) if external cold wind equipment, the power that bleeder resistance can bear is continuously 50% of built-in resistor rated power, otherwise the power that bleeder resistance can bear is continuously 20% of built-in resistor rated power.

It is as follows that regenerative braking logic concrete steps are processed in driver operation:

1) judge servo system whether break down state, Energy in use resistance and whether occur that resistance is too little to be warned whether, if so, turn off bleed-off circuit; No, proceed to the logic judgement to power condition;

2) determine whether protection point power is greater than power after filtering, if be greater than, opened leadage circuit and calculates this watt level of releasing, and power is greater than power peak if this is released, and power peak is defined as to the temporary variable of power calculation; If be less than power after filtering, turn off bleed-off circuit;

3) judge whether power is greater than protection power points power after filtering, if be greater than, sent overload and report to the police, show that regenerating power surpasses the ability that regeneration bleeder resistance can be released, otherwise do not need to report to the police.

If the situation Down Highway voltage that in step 2, ac power electricity input is invalid exists and busbar voltage is greater than 50V, still need to determine whether protection point power is greater than power after filtering.

Beneficial effect: the present invention compared with prior art, is for special operating mode, as long as the satisfied constraints proposing can be selected the bleeder resistance that meets the demand of releasing in a concrete system.The method is simple, can be widely used in driving control system.

Accompanying drawing explanation

Fig. 1 is flow chart of the present invention.

Fig. 2 is resistance protection initialize routine block diagram.

Fig. 3 is resistance protection monitoring program block diagram.

Fig. 4 is hardware overcurrent interrupt service routine block diagram.

Fig. 5 is electric system moving law schematic diagram.

Embodiment

Below in conjunction with Figure of description, the present invention is described in further detail:

Judge whether system needs bleeder resistance, selects according to demand the bleeder resistance that meets operating mode, thereby make after the operation of bleeder resistance connecting system, it is optimum that system reaches.With a concrete example, technical scheme of the present invention is described below:

1, given first drive parameter, as shown in table 1.

U b(V)	U av(V)	C(uF)	I m(A)	I bc(A)	R bmin(Ω)	R b(Ω)	P Rb(W)
								380	420	1680	16.9	11	38	50	40

Table 1. drive parameter table

2, with the completely unloaded example of motor, servo motor rotor moment of inertia J in experiment _mbe 1.28 * 10 ^-4kg/m ², maximum permissible revolution is 6000rpm, being converted into angular velocity omega is 628.3rad/s.

By regenerated energy formula, $E_m=\frac{1}{2}(J_m+J_l){{\mathrm{\&omega;}}_m}^2-{{3I}_m}^2\frac{R_m}{2}{t}_d-\frac{1}{2}{T_f\mathrm{\&omega;}}_m{t}_d+E_{\mathrm{\&Delta;f}},$ The known regenerated energy that braking produces under maximum speed is E _mfor 25.3J.By the absorbable energy theorem of bus filter capacitor the ENERGY E known, electric capacity can be stored _cfor 40.6J.Because the energy of regeneration is less than the energy that can store, therefore when motor is completely unloaded, braking does not need the energy of releasing, and does not just need to connect bleeder resistance yet.

3, the same above routine motor of investigating, with the example of motor shaft end band inertia load, and known back emf coefficient k _b=33V _rms/ krpm, the load of 50 times of rotor moment of inertias of axle head band, as shown in Figure 4, motor, with maximum 3 times of overload torques braking, supposes that friction torque is 0 to periodic duty rule.Concrete steps are as follows:

(1) determine as the case may be the bleeder resistance resistance meeting under operating mode.

1. by law of conservation of energy, judge whether system needs bleeder resistance.

According to regenerated energy formula $E_m=\frac{1}{2}(J_m+J_l){{\mathrm{\&omega;}}_m}^2-{{3I}_m}^2\frac{R_m}{2}{t}_d-\frac{1}{2}{T_f\mathrm{\&omega;}}_m{t}_d+E_{\mathrm{\&Delta;f}},$ Known J _l=50, J _m=64 * 10 ^-4kgm ², ω _m=314rad/s, I _m=16.5Arms, R _m=1 Ω, t _d=0.286s, all the other are 0.By can be calculated E _m=205J, visible regenerated energy is greater than the capacity that electric capacity can be stored, and needs the energy of releasing of regenerating, otherwise inevitable overvoltage.

2. by power constraint condition, determine the specification of bleeder resistance.

A, calculating peak power:

Foundation known k _b=33V _rms/ krpm, n=3krpm, I _m=16.5A _rms, R _m=1 Ω, calculates to obtain EMF _b=84.7V.

Foundation $P_{\max }=\sqrt{3}{\mathrm{EMF}}_b{I}_m,$ Calculate to obtain P _max=2421W.

B, calculating average power:

According to formula known E _m=205J, E _c=40.6J, t _cycle=1.2s, calculates to obtain P _av=137W.

Determine bleeder resistance specification limit:

According to formula P _max<P _{max_regen}with known U _b=380V, P _max=2421W, can determine bleeder resistance R _bneed be less than 59.6 Ω.

According to P _av<P _{av_regen}and consider the derate of different operating modes, known P _av=137W, air-cooled situation derate 50%, naturally cooling derate 20%.

, for air-cooled situation, the rated power of bleeder resistance should be greater than 274W, and for naturally cooling situation, the rated power of bleeder resistance should be greater than 685W.

3. determine the minimum resistance of bleeder resistance.

According to formula known U _ov=420V, I _bc=11A, calculates to obtain R _bmin=38.2 Ω, so bleeder resistance need be greater than 38.2 Ω.

To sum up, bleeder resistance resistance need be selected between 38.2～59.6 Ω, and it is air-cooled that rated power need be greater than 274W()/685W(is naturally cooling), select 40 Ω, the 300W(air-cooled)/700W(is naturally cooling) bleeder resistance be suitable.

(2), initialization regeneration bleeder resistance protection variable.

Bleeder resistance is accessed in servo system, and driver judges user profile.Use external regeneration bleeder resistance, the resistance of driver judgement user input is greater than the function of minimum value.Naturally cooling, the power that bleeder resistance can bear is continuously 137W.

(3), regenerative braking logic is processed in driver operation.

First judge servo system do not break down state, Energy in use resistance and do not occur that resistance is too little to be warned not.Proceed to the logic judgement to power condition.Determine that protection point power is greater than power after filtering, be greater than discharge voltage point voltage, open leadage circuit, can be calculated this power of releasing and be less than power peak, do not report to the police.

If secondly the invalid situation Down Highway voltage of judgement ac power electricity input exists, proceed to the logic judgement to power condition.Judgement protection point power and busbar voltage are greater than after filtering power and are greater than 50V, open leadage circuit, can be calculated this power of releasing and are less than power peak, do not report to the police.

(4), interrupt routine when bus hardware overcurrent.

In program operation process, bus hardware electric current is no more than maximum three-phase shortcircuit electric current 18A, does not carry out interrupt run program.

Claims (7)

1. a method of protecting regeneration bleeder resistance, is characterized in that, comprises the steps:

1) by calculating, check, select the vent discharge resistance that meets operating mode;

2), by bleeder resistance connecting system, system judges Set For Current state;

3) regenerative braking logic is processed in driver operation, and whether the regeneration bleeder resistance of judgement access meets the requirements;

4) if there is bus current overcurrent, interrupt routine is with protection bleeder resistance.

2. guard method according to claim 1, is characterized in that: the step of selecting the vent discharge resistance that meets operating mode in step 1 is as follows:

1) by law of conservation of energy, judge whether system needs bleeder resistance.

2) by power constraint condition, determine the specification of bleeder resistance.

3) determine the minimum resistance of bleeder resistance.

3. guard method according to claim 2, is characterized in that: whether system needs bleeder resistance, specifically comprises the steps:

1) the regenerated energy E of computing system _mwith the absorbable ENERGY E of bus filter capacitor _csize.

2) compare E _mwith E _csize, system is in unit situation, if E _m<E _c, do not need bleeder resistance, otherwise need; If system is in common bus situation do not need, otherwise need bleeder resistance; Work as E _mjduring <0, people is for being forced to 0 summation;

In step 1,

J _mfor motor self rotor moment of inertia, J _lfor mechanical load is folded to the moment of inertia of motor shaft end, ω _mfor the angular speed before decelerating through motor, I _mfor the phase current effective value of motor between deceleration period, R _mfor line resistance between motor phase, t _dfor the time of slowing down, the s of unit, T _ffor friction torque, E _{△ f}for the potential variation amount in Braking system process, potential energy increases then symbol for negative, and decrease of potential energy is being for just, E _cfor the absorbable energy of bus filter capacitor, C is driver bus filter capacitor, U _maxfor the accessible maximum voltage of bus before releasing, i.e. discharge voltage, U _nomfor bus average voltage, u _llline voltage for rectification input.

4. guard method according to claim 2, is characterized in that: the specification of determining bleeder resistance comprises the steps:

1) calculate the peak-pulse power P releasing _{max_regen}, maximum regeneration power P _max, average power P _av;

2) according to formula P _max<P _{max_regen}with determine bleeder resistance R _bmaximum;

3) calculate the minimum value of bleeder resistance;

4) according to actual condition, determine the rated power of bleeder resistance;

Wherein,

U _bfor the bus point voltage of releasing, P _maxissuable maximum regeneration power during for motor braking, I _mfor the phase current effective value of motor between deceleration period, EMF _bfor removing the winding back emf of loss part reduced voltage, k _bfor winding back emf constant, i.e. the 1000rpm back-emf effective value that rolls off the production line, n is the rotating speed that motor is moving before slowing down, EMF _bfor removing the winding back emf of loss part reduced voltage, t _cyclefor the one-period of motor cycle operation, deceleration time and non-deceleration time sum, U _ovfor bus overvoltage point voltage, I _bcthe direct current that can move continuously when radiator is 80 ℃ for bleeder pipe.

5. a kind of guard method of the bleeder resistance of regenerating according to claim 4, is characterized in that: in step 4, rated power determining step is as follows:

1) when system is used the built-in regeneration bleeder resistance bleeder resistance of maybe need not regenerating, during entirely by capacitive absorption, the rated power of bleeder resistance is 50% of built-in resistor rated power;

2), when using external regeneration bleeder resistance, driver judges whether the resistance of user's input is less than the function of regeneration bleeder resistance minimum value, if the minimum value of being less than needs to change external bleeder resistance; If be greater than, judge whether external cold wind equipment;

3) if external cold wind equipment, the power that bleeder resistance can bear is continuously 50% of built-in resistor rated power, otherwise the power that bleeder resistance can bear is continuously 20% of built-in resistor rated power.

6. guard method according to claim 1, is characterized in that: it is as follows that regenerative braking logic concrete steps are processed in driver operation:

1) judge servo system whether break down state, Energy in use resistance and whether occur that resistance is too little to be warned whether, if so, turn off bleed-off circuit; No, proceed to the logic judgement to power condition;

2) determine whether protection point power is greater than power after filtering, if be greater than, opened leadage circuit and calculates this watt level of releasing, and power is greater than power peak if this is released, and power peak is defined as to the temporary variable of power calculation; If be less than power after filtering, turn off bleed-off circuit;

3) judge whether power is greater than protection power points power after filtering, if be greater than, sent overload and report to the police, show that regenerating power surpasses the ability that regeneration bleeder resistance can be released, otherwise do not need to report to the police.

7. guard method according to claim 6, is characterized in that: if the situation Down Highway voltage that in step 2, ac power electricity input is invalid exists and busbar voltage is greater than 50V, still need to determine whether protection point power is greater than power after filtering.