CN1264269C - Power control device for lifting equipment - Google Patents

Abstract

The power control device for lifting equipment is used for controlling power between a power supply and a motor, and includes a converter, a capacitor and an inverter.

Description

Electric control device for lifting equipment

technical field

The invention relates to a power control device for lifting equipment, in particular to a power control device for lifting equipment that can effectively eliminate harmonics and process feedback power.

Background technique

In the past ten years, with the rapid economic development and the high improvement of the quality of life, industrial electricity consumption and electricity consumption for people's livelihood have grown significantly. In order to meet the quality of power supply, a large number of power plants and power transmission and distribution equipment must be added at appropriate locations. However, due to the rising awareness of environmental protection, it is difficult to find land for power plants and substations, so that the power company's plan to improve the quality of power supply cannot be carried out on schedule. In recent years, the power supply has started to turn red, especially during peak power consumption in hot summer, when there is almost a crisis of time-limited power supply. When power dispatching is already difficult, how can we take care of the quality of power supply.

Today, in order to improve product quality or work efficiency, most factories or office machinery and equipment have adopted automation equipment. When these automation devices are in operation, a large number of harmonics (Harmonic) or surges will be injected into the power system, affecting the quality of power supply for users in nearby areas. Furthermore, the causes of AC power interference that cause the degradation of power supply quality can be roughly divided into two categories: instantaneous voltage drop and high-order harmonics. The causes of instantaneous voltage drop include lightning AC, switch breakthrough, short circuit or grounding accident, surge caused by the opening and closing of large electric motors, electric welding machines and electric gas furnaces in the factory, building elevators, and air conditioners. surge and so on. The cause of high harmonics is large thyristor application machines, such as inverters, motor speed controllers, electric furnace temperature controllers, dimmers, induction cookers, microwave ovens, etc. The above-mentioned troublesome factors of high harmonics can be seen everywhere in daily life, and have a great impact on the quality of power supply. The mild ones will affect the sound quality or image, and the severe ones will damage electrical equipment or shorten the service life of electrical equipment. Therefore, at present, electrical equipment is usually equipped with a power control device to eliminate the interference components such as instantaneous voltage drop and high harmonics in the mains, especially for electrical equipment that does not allow faults to occur. Important, such as lifting equipment such as elevators and escalators.

As shown in FIG. 1 , a power control device 1 of conventional lifting equipment is used to control the power conversion between a power source 11 and a motor 12 . The lifting device is an elevator as an example, and the power supplied by the power supply 11 is three-phase power R, S, T. The motor 12 is used to control the rotation of the winding machine 13, and the steel wire rope 16 having a carriage 14 at one end and a counterweight 15 at one end is wound on the winding machine 13. The power control device 1 has a converter 17 , a capacitor 18 and an inverter 19 . In this way, when the AC power of the power supply 11 is fed into the power control device 1, the converter 17 will convert it into DC power, and feed it into the inverter 19 through the capacitor 18, and then the inverter 19 is subjected to PWM (Pulse width modulation , pulse width modulation) control circuit 191 to convert the DC power into AC power with variable voltage and frequency and output it to the motor 12, so that the motor 12 drives the carriage 14 up or down due to electric power.

In this way, although the conventional power control device 1 converts the power source 11 into power suitable for the operation of the motor 12, since the converter 17 is a diode rectifier, it can only effectively convert AC to DC and cannot effectively eliminate harmonics. However, as mentioned above, there are more and more factors that cause harmonics in daily life, and even if the power supply 11 supplies power with almost no harmonics, the actions of the converter 17 and inverter 19 in the power control device 1 may also cause harmonics. Harmonics have caused the power control device 1 to fail to provide sufficient and good-quality power, which has led to an increase in the probability of failure of the lifting equipment, making news of failure or even burning of the lifting equipment caused by harmonics common. Therefore, for safety considerations, people's requirements for the power control device 1 are no longer limited to power conversion and hope that it can effectively improve the ability to eliminate harmonics, so that many effective methods for eliminating harmonics have emerged, such as using PWM switches A circuit (such as the inverter 19 of the PWM switching circuit in FIG. 1 ) is used as the converter 17 or an active filter (Active filter) is configured between the power source 11 and the converter 17 .

FIG. 2 shows a detailed circuit diagram of a conventional active filter 2 . The active filter 2 is connected to the power supply 11 to supply power to the line 20 of the converter 17 (if it is the three-phase power of FIG. 1, then the line 20 should be three lines, which are represented by one line for convenience of illustration). First, it is assumed that the load current I _L fed into the converter 17 has a waveform as shown in FIG. 3 , which is composed of a sine wave current I ₁ supplied by the power supply 11 and a harmonic I _h . In this way, the harmonic accumulator 21 of the active filter 2 senses the load current I _L of the line 20 to separate the harmonic current I _h as shown in FIG. 4 . At the same time, the DC voltage controller 23 will be based on the voltage V _d of the capacitor 221 in the PWM switch circuit 22 (this voltage V _d is the same as the voltage of the capacitor 18 of the power control device 1), a predetermined voltage V _df and the voltage V _s of the power supply 11 to generate a comparison signal I _a , and then compare the comparison signal I _a with the harmonic current I _h and then feed the current I _c sensed from the PWM switch circuit 22 into the gate pulse generator 24 to generate the PWM switch The control signals for activating or closing each transistor 222 in the circuit 22 are input to the PWM _{switch circuit 22, so that the PWM switch circuit 22 outputs a compensation current Ic (} as shown in FIG. In this way, the harmonic current I _h on the line 20 and the compensation current I _c cancel each other out. Therefore, the defect that the conventional power control device 1 cannot be effectively filtered can be solved.

In addition, because the motor 12 in the lifting device may be driven or fed back due to the difference between the direction of rotation of the winding machine 13 and the weight of the side weight of the carriage 14 and the weight of the counterweight 15 . Specifically, when the housing 14 is raised with a load equivalent to its capacity, the electric motor 12 receives power supplied from the inverter 19 for driving operation. On the contrary, when the case 14 is lowered under the same circumstances, the motor 12 will operate in feedback to generate feedback power to the capacitor 18 . In this way, when the feedback power is greater than the capacity of the capacitor 18, the components will be burned. Therefore, there are many ways to solve the feedback power at present, one of which is "a processing device for controlling the feedback power of elevators" proposed by Mitsubishi Electric Co., Ltd. in Taiwan Patent No. 75200221, which is The feedback power is recovered and used through a power feedback processor.

FIG. 6 is a PWM power feedback processor 3 . The processor 3 basically has a DC voltage controller 31 , a gate pulse generator 32 and a PWM switch circuit 33 . The capacitor 331 in the PWM switch circuit 33 is connected in parallel with the capacitor 18 of the power control device 1 in FIG. 1 to have the same voltage V _d . When the voltage of the capacitor 331 is higher than a predetermined voltage V _df , the DC voltage controller 31 will generate a synchronous comparison according to the voltage V _d of the capacitor 331 in the PWM switch circuit 33, the predetermined voltage V _df and the voltage V _s of the power supply 11 signal I _a , and then compare the synchronous comparison signal I _a with the current I _c sensed from the PWM switch circuit 33 and then feed it into the grid pulse generator 32 to generate the activation of each transistor 332 in the PWM switch circuit 33 The control signal of turning on or off is input to the PWM switch circuit 33, so that the PWM switch circuit 33 converts the power stored in the capacitor 331 into recovered power in phase with the power of the power supply 11 and feeds it to the power supply 11 for reuse. In this way, not only can the problem of failure caused by excessive feedback power be solved, but also the feedback power can be regenerated. In addition, the PWM power feedback processor 3 can be used as a PWM converter to eliminate harmonics, but its required power must be equivalent to the power of the motor 12. For example, if it is only used for feedback power processing, its power may only need One-half of the power of the motor 12, and when used as a converter, it must be equal to the power of the motor 12, resulting in a considerable power required by the PWM power feedback processor 3 capable of eliminating harmonics and feedback power processing. However, the size and price increase several times with the increase of power, so the feedback power processor 3 is also quite large and expensive.

Therefore, if the PWM power feedback processor 3 is used to deal with the problem of harmonics and feedback power, there are disadvantages of large power, large size and high cost. On the other hand, the active filter 2 can provide the function of eliminating harmonics with a lower power capacity (such as one-half of the power of the motor 12). Compared with the harmonic elimination function of the PWM power feedback processor 3, it has lower power, The advantages of small size and low cost, however, cannot solve the problem of feedback power regeneration. Therefore, if the harmonic elimination function can be provided by the active filter 2, the required power of the feedback power processor 3 only needs to meet the requirements of the feedback power, thus solving the shortcomings of large power, large size and high cost . However, if the power control device of the lifting equipment is directly equipped with an active filter 2 and a power feedback processor 3 for use in harmonic elimination and power regeneration, the lower power active filter 2 and power The feedback processor 3 replaces the original high-power power feedback processor 3, thereby achieving the effect of reducing power and cost. However, since the functions of eliminating harmonics and feedback power recovery are each a single machine, the cost and cost Volume remains high.

In fact, the circuit structure of the active filter 2 and the power feedback processor 3 is quite similar, both having PWM switch circuits 22, 33, DC voltage controllers 23, 31 and grid pulse generators 24, 32, and both The use timing of the active filter 2 is staggered when the power is supplied, and the power feedback processor 3 is used when the power is fed back. Therefore, the inventor of this case thought that if a single device is used to provide the two functions of the active filter 2 and the power feedback processor 3, compared to the original case of using both at the same time, the power, cost and volume can be effectively reduced .

Contents of the invention

An object of the present invention is to provide a power control device for lifting equipment to achieve both harmonic elimination and power feedback functions.

Another object of the present invention is to provide a power control device for lifting equipment, so as to reduce the power efficiency.

Another object of the present invention is to provide a power control device for lifting equipment to reduce costs.

Another object of the present invention is to provide a power control device for lifting equipment to achieve the effect of reducing the volume.

Therefore, the power control device of the lifting equipment of the present invention includes a converter, a capacitor, an inverter and a control set, wherein the converter is used to convert the AC power of a power supply into DC power; the capacitor is connected to the converter the output side of the inverter; the inverter converts the DC power of the capacitor into AC power of variable voltage and frequency to a motor, and the motor receives the power of the inverter to drive a load up or down; and the control set connects the capacitor and The input side of the converter is switched in one of a first state and a second state, and when the control set senses that the voltage of the capacitor is less than a predetermined value, the control set is in the first state and clears the harmonics in the AC power of the power supply to provide an active filtering function, and when the control set senses that the voltage of the capacitor is greater than the predetermined value, the control set is in the second state and feeds back the power of the capacitor to the power supply to provide the feedback power conversion function.

Description of drawings

Figure 1 is a schematic diagram of a conventional power control device for lifting equipment, which is used in conjunction with a lifting device that is an elevator;

Fig. 2 is a detailed circuit diagram of an active filter of a conventional power control device;

FIG. 3 is a waveform diagram of an example of the load current IL in FIG. 2;

Fig. 4 is the waveform diagram of the harmonic current Ih in the load current IL in Fig. 2;

Fig. 5 is the oscillogram of the compensation current Ic output by the active filter in Fig. 2;

Fig. 6 is a detailed circuit diagram of a PWM converter for feedback power of a conventional power control device;

Fig. 7 is a detailed circuit diagram of a preferred embodiment of the present invention.

Detailed ways

For the purpose of illustration, the lifting equipment in the following embodiments is taken as an example of an elevator, but those skilled in the art will know that the lifting equipment can also be other types of lifting equipment that can provide ascending and descending, such as escalators, and are not limited Description of this article.

As shown in FIG. 7 , an embodiment of the power control device 4 of the lifting equipment of the present invention includes a converter 41 , a capacitor 42 , an inverter 43 , a motor 44 and a control set 5 .

The converter 41 is used for converting the AC power of a power source 6 into DC power. The capacitor 42 is connected to the output side 411 of the converter 41 . The inverter 43 converts the DC power of the capacitor 42 into AC power with variable voltage and frequency, and a motor 44 receives the power from the inverter 43 and drives a load 71 (such as a car) to rise or fall. In this example, the power supply 6 supplies three-phase AC power, the converter 41 is a three-phase bridge rectifier, and the inverter 43 is a PWM inverter with a PWM switch circuit 431 and a PWM control circuit for controlling the PWM switch circuit 431 432. In addition, the motor 44 is determined to be driven or regenerative depending on the weight difference between the load 71 and the counterweight 72 and the direction of travel (ascending or descending) of the load 71 . Here, since the aforementioned components 41-44 are not the focus of improvement in this case and are well known to those skilled in the art, they will not be repeated here.

The key point of improvement in this case is to enable the control set 5 to provide the functions of harmonic filtering and power regeneration in different states. The control set 5 is connected to the capacitor 42 and the input side 412 of the converter 41 and switched to one of a first state (referring to the power driving state) and a second state (referring to the power regenerative state), when the control set 5 senses When the voltage of the capacitor 42 is less than a predetermined value Vdcf, the control set 5 is in the first state and eliminates harmonics in the AC power of the power source 6 to provide an active filtering function. And when the control set 5 senses that the voltage of the capacitor 42 is greater than the predetermined value Vdcf, the control set 5 is in the second state and feeds back the power of the capacitor 42 to the power supply 6 to provide a feedback power conversion function. The control set 5 of this example has a harmonic calculator (Harmonic accumulator) 51, a DC voltage controller (DC voltage controller) 52, a grid pulse generator 53, a PWM switch circuit 54, a switch 55, two groups Current detectors 56 , 57 , a voltage detector 58 and a comparator 59 .

The harmonic calculator 51 receives the load current IL synthesized by the three-phase power lines 61 , 62 , and 63 at the input side 412 of the converter 41 sensed by the current detector 56 and separates and outputs the harmonic current Ih in the load current IL. The harmonic calculator 51 in this example has a fundamental calculator (fundamental calculator) 511 and a comparator 512 . The fundamental wave calculator 511 is connected to the current detector 56 (referring to the first current detector) to receive the load current IL and calculate the fundamental wave current I1 output by the power supply 6 according to the load current IL (this fundamental wave current I1 refers to the 6 output the original current without harmonic interference). Then, the comparator 512 receives the load current IL and the fundamental wave current I1 to compare the output harmonic current Ih.

The DC voltage controller 52 has a comparator 521 , an automatic voltage regulator (Automatic Voltage Regulator, AVR) 522 and a multiplier 523 . The comparator 521 receives a voltage Edc and a predetermined value Vdcf to compare the voltage difference between the two and input it into the automatic voltage regulator 522, and then outputs a comparison current Iar for proper compensation through calculation, and then compares the current Iar with the power 6 converted by a voltage converter. The voltage Vs of the multiplier 523 is multiplied to generate a sine wave signal IC with a variable magnitude and synchronous with the power supply voltage. In addition, the voltage Edc is obtained by the voltage detector 58 sensing the capacitor 541 in the PWM switch circuit 54 . The capacitor 541 is connected in parallel with the capacitor 42 between the converter 41 and the inverter 43 and has the same voltage value.

The switch 55 connects the output side of the harmonic operator 51 (that is, the output end of the comparator 512 of the harmonic operator 51) and the comparator 59, and the switch 55 is turned on (ON) in the first state so that the harmonic current Ih can be Feeds to comparator 59. On the contrary, in the second state, the switch 55 is closed (OFF) so that the harmonic calculator 51 and the comparator 59 are no longer electrically connected. At this moment, when the comparator 59 is in the first state, it compares the calculated harmonic current Ih with the sine wave signal IC and then outputs a first current Iar*. In addition, the switch 55 can be implemented by software or hardware, and the switch 55 in this example is implemented by software control, that is, whether the harmonic current Ih is fed into the comparator 59 is controlled by software.

The gate pulse generator 53 has a comparator 531 , an automatic current regulator (Automatic Current Regulator, ACR) 532 and a PWM controller 533 . The comparator 531 compares the first current Iar* with the second current Ia (the second current Ia is the current signal obtained by detecting the output side 540 of the PWM switch circuit 54 by the current detector 57 (ie, the second current detector) ) into the PWM controller 533 after being fed into the automatic current regulator 532 for calculation and compensation, so that the PWM controller 533 can output a PWM square wave with variable frequency width and variable voltage to control each transistor 542 in the PWM switch circuit 54 opening and closing. In this way, in the first state, the inverse harmonic signal Ih can be output due to the control of the gate pulse generator 53 to eliminate the harmonic current Ih in the load current IL, and the harmonic current Ih stored in the capacitor 541 can be stored in the second state The power is converted into regenerative power in the same phase as the power of the power source 6 and fed to the power source 6 .

In addition, the power control device 4 further includes a feedback power consumption circuit 45, which is a circuit for protecting the consumption feedback power system in case the feedback power system does not operate when the motor 44 is changed to the feedback power state. The feedback power consumption circuit 45 of this example is located at the output side 411 of the converter 41 and is connected in parallel with the capacitor 42, and is connected in series with a regenerative resistor 451 and a switch 452 which is a transistor. And when it exceeds a certain dangerous value (this dangerous value is higher than the predetermined value Vdcf and lower than the withstand voltage value of the capacitor 42), it is turned on to consume the voltage value Vdc of the capacitor 42 in real time, thereby reducing the probability of failure of the power control device 4 , in order to achieve the effect of improving product stability. For example, assuming that the withstand voltage value of the capacitor 42 is 450V, the predetermined value Vdcf is 370V, and the dangerous value is 390V, if the voltage value Vdc of the capacitor 42 is 340V, then it is in the first state, and the motor 44 receives power from the power supply 6 And in the state of electric drive. And when the voltage value Vdc of the capacitor 42 is 370V, the control set 5 is changed from the first state to the second state and the electric motor 44 also becomes the electric power regenerative operation state to feed back electric power to the power supply 6. At this time, the electric power consumption circuit 45 is fed back. is not activated. When the electric motor 44 has turned into power regenerative operation but the control set 5 does not enter the second state to process the feedback power in real time, the voltage value Vdc of the capacitor 42 will continue to rise, and when the voltage value Vdc rises to 390V, the switch 452 is activated to use the regenerative resistor 451 to consume the regenerative power stored in the capacitor 42 . In this way, with the feedback power consumption circuit 45 , it can be used as a protection measure for real-time power consumption when the control set 5 does not act in time, thereby achieving the effects of avoiding failure and improving safety.

According to the above-mentioned components and interrelationships, the signal processing processes of the first state and the second state will be described in the following, so as to make this embodiment easier to understand.

(1) First state

When the power control device 4 supplies power to the motor 44 and the voltage Edc of the capacitor 541 (also referred to as the voltage of the capacitor 42) is less than the predetermined value Vdcf, the control set 5 operates in the first state which can be regarded as the active filter function and Turn on switch 55 in control set 5. In this way, the harmonic calculator 51 in the control set 5 receives the load current IL through the current detector 56 and analyzes the harmonic current Ih in the load current IL after calculation. At the same time, the DC voltage controller 52 compares the predetermined value Vdcf with the voltage Edc of the capacitor 541 and multiplies it with the voltage Vs of the power source 6 after calculation and compensation to generate a sine wave signal IC. Then, after the sine wave signal IC is compared with the harmonic current Ih (the result of the comparison operation Iar* will be the same size as the harmonic current Ih), it is compared with the current Ia sensed by the current detector 57 again, and finally The gate pulse generator 53 generates a PWM square wave with variable bandwidth and variable voltage to control the PWM switch circuit 54, so as to generate an anti-phase harmonic current IL and feed it to the input side 412 circuit of the converter 41, thereby eliminating the load Harmonic current Ih in current IL.

(2) Second state

When the ratio of the load 71 to the balance weight 72 is not equal and the motor 44 enters the generator state (regenerative power state), the control set 5 will enter the second state (power regenerative state) and the switch 55 will be closed (that is, an open circuit, As a result, the harmonic current Ih cannot be input into the comparator 59). In this way, the DC voltage controller 52 compares the predetermined value Vdcf with the voltage Edc of the capacitor 541, calculates and compensates, and multiplies the product with the voltage Vs of the power supply 6 to generate a sine wave signal Iar*, which is then compared with the current of the current detector 57 After comparison of Ia, the PWM square wave with variable frequency width and variable voltage is generated by the gate pulse generator 53 to control the PWM switch circuit 54 to send back too much feedback power in the capacitor 541 to the power supply 6, so as to Reach the effect of electricity recycling. Here, the signal of the product of the power supply voltage VS is compared with the current Ia passing through the current detector 57, mainly for the purpose of generating a sinusoidal feedback current with the same phase as the voltage of the power supply 6 (that is, output by the PWM switch circuit 54 current) to reduce the higher harmonics (THID) in the feedback current. In addition, when the control set 5 is in the second state, the harmonic calculator 51 can be turned off and does not operate, so as to further save power consumption.

To sum up, the power control device 4 of the present invention can indeed provide an active filtering function in the first state (power supply) by means of the control set 5 to eliminate the harmonic current Ih in the load current IL, and in the second state In the state (power feedback), power feedback conversion is provided to convert excessive feedback power into a feedback current that is in phase with the voltage VS of the power supply 6 and feed it back to the power supply 6, so as to achieve both active filtering and active filtering with a single control set 5 The purpose of the invention of the power feedback conversion function. In this way, the control set 5 can eliminate the harmonic current Ih in the load current IL in the first state and cooperate with the rectification of the converter 41 to eliminate the pulse current (non-sinusoidal current) in the load current IL, so that the converter 41 The current of the output side 411 is DC power without harmonic current Ih and is a sine wave, and when the control set 5 is in the second state, the excessive feedback power in the capacitor 541 can be converted into feedback with the same phase as the voltage of the power supply 6 The current is fed back to the power supply 6 . Therefore, since the required power of the active filter is much lower than the power feedback processor 3 (for example, one-half or one-third) when eliminating harmonics, the power required by the control set 5 of the present invention will be much lower. It is lower than the power feedback processor 3 and can achieve the effects of low power, small size and low cost. In addition, if compared with the method of separately matching an active filter 2 and a power feedback processor 3, the power control device 4 of the present invention uses a single control set 5 to achieve both active filtering and feedback power conversion functions, and thus also The effect of greatly reducing cost and volume can be achieved.

Claims (9)

1. the power control unit of a jacking equipment is characterized in that it includes:

One transducer becomes direct current power in order to the alternating electromotive force of changing a power supply;

One capacitor is the outlet side that is connected in this transducer;

One inverter is that the direct current power of this capacitor of conversion becomes the variable voltage variable frequency alternating electromotive force to give a motor, and the electric power that this motor receives this inverter rises or descends to drive a load; And

One control set, this control set comprises the harmonic wave arithmetic unit, switch, the pulse wave width modulation unit, the first electric current detector, the voltage detector, the second electric current detector, this control set connect the input side of this capacitor and this transducer and switch on one first state and one second state in one, the voltage that senses this capacitor when this control set is during less than a predetermined value, the harmonic wave that this control set is arranged in this first state and eliminates the alternating electromotive force of this power supply, so that initiatively filter function to be provided, and the voltage that senses this capacitor when this control set is during greater than this predetermined value, this control set is positioned at this second state and the electric feedback of this capacitor is given this power supply, so that the feedback power translation function to be provided.

2. the power control unit of jacking equipment as claimed in claim 1 is characterized in that this control set comprises:

One harmonic wave arithmetic unit is to connect the input side of this transducer and in order to calculate the harmonic wave that it comprises in the electric power by this power supply;

One switch, have one first end and one second end, and this first end is to connect this harmonic wave arithmetic unit, and this switch opens so that this harmonic wave is sent to this second end through this switch in this first state, closes so that harmonic wave no longer is sent to second end through this switch when being positioned at this second state;

One pulse wave width modulation unit, it is second end that connects this switch, and receive the anti-phase signal of harmonic wave in the harmonic wave of this harmonic wave integrating instrument and output and the alternating electromotive force of this power supply in this first state, eliminating the harmonic wave in this alternating electromotive force, and in this second state, will give this power supply from the power conversions feedback of this capacitor.

3. the power control unit of jacking equipment as claimed in claim 2 is characterized in that this pulse wave width modulation unit has:

One direct current voltage controller, be the voltage of relatively this capacitor and this predetermined value and through compensation operation again with this power source voltage relatively after output;

One comparator is to receive the relatively back output of signal of harmonic wave and the output of this dc voltage controller in this first state from this harmonic wave arithmetic unit, and directly exports the signal of this dc voltage controller when this second state;

One grid pulse generator is a square wave of exporting a variable frequency range and variable voltage according to the output signal of this comparator; And

One pulse width modulation circuit, be according to this grid pulse generator output square wave control in the anti-phase signal of this first state output and this harmonic wave with in the electric power of this this capacitor stores of second state exchange for the electric power of the electric power homophase of this power supply to be fed back to this power supply.

4. the power control unit of jacking equipment as claimed in claim 2 is characterized in that: this control set more comprises one first electric current detector, in order to the electric current of the input side of this transducer of sensing to import this harmonic wave arithmetic unit.

5. the power control unit of jacking equipment as claimed in claim 3 is characterized in that: this control set more comprises a voltage detector, in order to the voltage of this capacitor of sensing and import this dc voltage controller.

6. the power control unit of jacking equipment as claimed in claim 3, it is characterized in that: this control set more comprises one second electric current detector, in order to electric current and this grid pulse generator of feed-in of the outlet side of this pulse width modulation circuit of sensing, so that this grid pulse generator is with the output signal of this comparator and this current ratio square wave of back beginning output one variable frequency range and variable voltage.

7. the power control unit of jacking equipment as claimed in claim 1, it is characterized in that: this power control unit more comprises the switch of connecting with this resistance with a resistance of this capacitor parallel connection, and this switch is to activate so that the electric power of this this capacitor of resistance consumption in second state in good time.

8. the power control unit of jacking equipment as claimed in claim 7 is characterized in that: this switch is that the electric power of this capacitor is activated when surpassing a dangerous values, so that this resistance action, and this dangerous values is to be higher than this predetermined value.

9. the power control unit of jacking equipment as claimed in claim 7, it is characterized in that: this switch is a transistor.

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