CN212183441U - Pumping unit frequency converter with brake voltage limitation - Google Patents
Pumping unit frequency converter with brake voltage limitation Download PDFInfo
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- CN212183441U CN212183441U CN201922371955.9U CN201922371955U CN212183441U CN 212183441 U CN212183441 U CN 212183441U CN 201922371955 U CN201922371955 U CN 201922371955U CN 212183441 U CN212183441 U CN 212183441U
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Abstract
A pumping unit frequency converter with brake voltage limitation comprises a voltage sampling module, an amplitude limiting adjustment module and an overvoltage adjustment module. When the direct-current bus voltage sampled by the voltage acquisition module is greater than the direct-current bus limit value set by the amplitude limiting adjustment module, the amplitude limiting adjustment module is triggered to adjust the minimum output torque amplitude limiting value of the controller, the feedback braking energy is reduced, the motor works in the first quadrant, the partial energy is converted into mechanical energy of a mechanical system, and the rotating speed of the motor is increased by the increased mechanical energy; the sampled motor rotating speed is greater than the maximum allowable motor rotating speed given by the amplitude limiting adjustment module, the minimum output torque amplitude limiting value of the controller is recovered, the motor rotating speed is reduced, the voltage of the direct-current bus is increased, and the frequency converter works in a balanced state of the motor speed limiting and the frequency converter direct-current bus voltage limiting; when the sampled DC bus voltage is greater than the given maximum DC bus voltage of the overvoltage adjustment module, the braking circuit is switched on, energy is consumed through the power resistor R, and the voltage is prevented from being too high.
Description
Technical Field
The utility model relates to a converter especially relates to a pumping unit converter.
Background
With the development of science and technology, the advantages of frequency converters in speed regulation and energy conservation are widely accepted. The soft start and the soft stop are realized, the rotating speed of the motor can be smoothly changed according to the requirements of users, and the device is suitable for energy-saving modification of the pumping unit. However, because the pumping unit is a potential energy load, when the balance block is lowered or the horse head is lifted, an energy braking feedback state exists, namely, regenerative power generation, and the generated electric energy flows back to the bus capacitor of the frequency converter through the freewheeling diode of the inverter module, so that the bus voltage is overhigh in serious conditions, and a main circuit device is made to be: the filter capacitor and the IGBT module are damaged due to overvoltage, so that the energy of the filter capacitor and the IGBT module must be processed.
The currently commonly used pumping unit frequency converters comprise the following two types:
general converter: the main loop is a diode uncontrollable rectification and PWM controllable inversion part. In order to consume the energy of regeneration power generation, an energy consumption circuit comprising a resistor and a transistor is connected in parallel at the side of a direct current bridge, when the voltage of a direct current loop exceeds a specified value, the direct current loop releases energy through a brake resistor when the energy consumption circuit is switched on.
Four-quadrant converter: the rectification and inversion parts of the main loop are controlled by PWM, when the motor is in a regenerative power generation running state, the inverter circuit is controlled to work in a rectification state, power is supplied to the direct current side through a diode of the inverter circuit, the rectifier circuit works in an inversion state, and the direct current side feeds back electric energy to a power grid through an IGBT. The scheme has the defects that the main circuit is high in cost and complex in control, and is not commonly adopted.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a beam-pumping unit converter with braking voltage restriction. Use the utility model discloses a pumping unit converter increases voltage sampling module, amplitude limiting adjustment module, excessive pressure adjustment module on the basis of general converter, can improve the not enough of current general converter.
The utility model discloses on the basis of general converter, should directly turn into the potential energy of balancing piece by the renewable energy that the brake resistance consumed under the power generation state, store in mechanical system. Due to the mechanical reversing action of the crank, the stored mechanical potential energy is converted into kinetic energy again, so that the electric energy fed back by the motor is fully utilized, and the effect of saving the electric energy is achieved.
The main principle of the utility model is as follows:
according to the working characteristics of the three-phase alternating current motor, the motor works in quadrants I and III to be a motor, and works in quadrants II and IV to be a generator. When the negative torque of the pumping unit system drags the motor, the motor can move at a rotating speed higher than the synchronous rotating speed of the motor, the output torque of the motor is negative, the motor is in a positive feedback braking state of a second quadrant at the moment, mechanical energy in the pumping unit system is converted into electric energy, the motor becomes a generator, and the voltage of a direct current bus of a frequency converter is increased. The utility model discloses a voltage sampling module detects converter direct current bus voltage, and amplitude limiting adjustment module judges that the motor is in the electric state still power generation state, and when the motor was in the power generation state, amplitude limiting adjustment module acted on the controller, changed converter output torque amplitude limiting value, made motor work in the I quadrant, prevented resistance torque's production, turned into mechanical energy by the renewable energy that the motor electricity generation produced originally and stored in mechanical system, reduced the consumption of energy.
The utility model discloses a beam-pumping unit converter main circuit includes the uncontrolled rectifier module of three-phase, the brake unit, voltage sampling module, rotational speed sampling module, the amplitude limiting regulation module, excessive pressure adjustment module, a controller, filter capacitor and three-phase contravariant module, voltage sampling module detects converter direct current bus-bar voltage, rotational speed sampling module detects motor speed, the direct current bus-bar voltage that amplitude limiting regulation module obtained according to the sampling, motor speed acts on the controller, controller output control signal is in three-phase contravariant module, three-phase contravariant module control motor. The overvoltage adjusting module gives a maximum allowable voltage, and when the voltage of the direct current bus detected by the voltage sampling module is greater than the given maximum allowable voltage, the overvoltage adjusting module turns on the braking unit and consumes energy through the braking resistor R.
The invention adopts a three-level discharge control strategy: namely output torque amplitude limiting, motor speed limiting and direct current side voltage limiting, the braking voltage limitation on the frequency converter of the oil pumping unit is specifically as follows:
output torque clipping: the motor is in a power generation state, the given voltage reference value of the amplitude limiting adjustment module is different from the voltage value detected by the voltage sampling module, the minimum torque amplitude limiting value of the controller is changed through PI (proportional integral) adjustment output of the amplitude limiting adjustment module, the minimum torque output by the motor is gradually adjusted to zero, the motor does not generate power after the generated energy is reduced, and therefore the direct-current bus voltage is limited, the energy is converted into mechanical energy of a four-connecting-rod system of the pumping unit, and energy loss is avoided.
Limiting the speed of the motor: most of the system mechanical energy generated by output torque amplitude limiting is converted into kinetic energy of a crank balance block, and the rotating speed of the motor is increased. When the balance of the oil pumping unit system is poor or an oil well is gradually pumped out, the kinetic energy of the balance block generated by conversion is large, the rotating speed of the motor is too high, and the mechanical system runs in an overload state and is easy to damage after long-time working. When the rotating speed of the motor detected by the rotating speed sampling module exceeds the maximum allowable value of the given rotating speed of the amplitude limiting adjusting module, the switch module of the amplitude limiting adjusting module is switched off, the controller recovers the output torque amplitude limiting value of the motor, the motor is in a power generation state, the rotating speed is reduced, the frequency converter works in a balance state of the motor speed limiting and the direct-current bus voltage limiting, the energy loss is reduced to a certain extent, and the overload operation of a mechanical system is also avoided.
Direct current side voltage limiting: under the motor speed limit state, the direct current bus voltage of the frequency converter continuously rises, and the overhigh direct current bus voltage can cause energy loss, also greatly influence the power factor of the power grid side, and also damage the power device and the filter capacitor of the main circuit in serious conditions. When the voltage on the direct current side exceeds the maximum allowable voltage given by the overvoltage adjusting module, the overvoltage adjusting module turns on the braking unit, and energy is consumed through a braking resistor similarly to a universal frequency converter. Under normal conditions, the pumping unit works under the states of output torque amplitude limiting and motor speed limiting, the direct current side voltage limiting is equivalent to a primary protection circuit, and compared with a general frequency converter, the service life of a brake resistor is greatly prolonged.
Compare with general converter, the utility model discloses a converter has restricted direct current bus voltage, has reduced energy loss, only needs closed loop to adjust output torque's amplitude limiting value, can realize the converter operation at the balanced state of motor speed limit and direct current bus voltage limiting.
Drawings
FIG. 1 is a graph of constant power operating characteristics of a three-phase AC motor;
FIG. 2 is a schematic diagram of the frequency converter system of the pumping unit of the present invention;
FIG. 3 is a control strategy structure diagram of the frequency converter of the pumping unit of the present invention;
fig. 4 is the utility model discloses tertiary control flow chart of releasing of beam-pumping unit converter.
In the figure, a constant power curve of a J01 three-phase alternating-current motor, a J02 reverse braking power generation amount, a C1 first filter capacitor, a C2 aluminum foil capacitor, a C3 third filter capacitor, a C4 fourth filter capacitor, a J power device IGBT, an R brake resistor, an M motor, 11 three-phase uncontrolled rectifier module, 12 brake units, 13 voltage sampling modules, 14 and 102 amplitude limiting adjustment modules, 15 overvoltage adjustment modules, 16 controllers, 17 rotating speed sampling modules, 18 and 113 three-phase inversion modules, 101 vector control modules, 103, 104, 105 and 106PI adjustment modules, 107 switch modules, 108 output torque amplitude limiting modules, 109, 111 and 112 vector control coordinate conversion modules, and 110 vector control wave generation modules.
Detailed Description
The invention is further described below with reference to the accompanying drawings and the detailed description.
Fig. 2 is used the utility model discloses a pumping unit converter system architecture sketch map, pumping unit converter system's main circuit includes that the three-phase does not control rectifier module 11, brake unit 12, voltage sampling module 13, amplitude limiting adjustment module 14, excessive pressure adjustment module 15, controller 16, rotational speed sampling module 17, filter capacitor C1 ~ C4 and three-phase contravariant module 18, voltage sampling module 13 detects converter direct current bus-bar voltage, rotational speed sampling module 17 detects the motor speed, direct current bus-bar voltage U that amplitude limiting adjustment module 14 obtained according to the samplingdMotor speed nrelActing on a controller, the controller16 outputs control signals to the three-phase inversion module 18, and the three-phase inversion module 18 outputs voltage to control the motor M. The overvoltage regulation module 15 sets the maximum permissible voltage UmaxWhen the voltage sampling module detects the DC bus voltage UdGreater than a given maximum allowable voltage UmaxThe overvoltage adjustment module 15 turns on the brake unit 12, consuming energy through the brake resistor R.
As shown in fig. 3, the frequency converter control strategy of the pumping unit of the present invention is mainly implemented by the vector control module 101 and the amplitude limiting adjustment module 102. The rotating speed closed-loop vector control module comprises PI adjusting modules 103, 104, 105 and 106, coordinate transformation modules 109, 111 and 112 and a wave-generating module 110, and when the rotating speed closed-loop vector control module works in a power generation state, the rotating speed closed-loop vector control module acts on an amplitude limiting module 108 through an amplitude limiting adjusting module 102 to change the amplitude limiting value of the amplitude limiting module 108, so that a motor does not generate power any more, and the specific implementation steps are as shown in FIG. 4:
in step S01, the sampled DC bus voltage U of the frequency converterdAnd motor speed nrelFeeding the voltage to the amplitude limiting regulation module 14 and the overvoltage regulation module 15, and setting a reference voltage U by the amplitude limiting regulation module 14dcAnd a maximum allowable rotation speed nmaxThe overvoltage regulation module 15 sets the maximum permissible voltage Umax；
In steps S02, S03, and S04, the amplitude limiting adjustment module 14 samples the dc bus voltage UdWith a given reference voltage UdAnd a maximum allowable rotation speed nmaxComparing, the overvoltage adjusting module 15 will sample the DC bus voltage UdWith a given maximum allowable voltage UmaxComparing, and dividing the compared results into four categories of normal electric state, direct current bus boosting, motor overspeed and direct current bus overvoltage;
in step S05, when the DC bus voltage U of the frequency converterdLess than the reference voltage U given by the clipping adjustment module 14dcThe motor is normally operated in the motoring mode, and the controller 16 sets the motor speed nrefWith sampled motor speed nrelMaking a difference, passing through a PI adjusting module 104 and an amplitude limiting module 108, and adjusting the motor at a constant rotating speed through a vector control module 101;
in step S07, the dc bus voltage U of the inverterdGreater than the reference voltage U given by the clipping adjustment module 14dcThe motor works in a power generation state and the motor rotating speed nrelLess than the maximum allowable speed n of the given motormaxThe switch module 107 is closed, and the voltage sampling module 13 samples the DC bus voltage UdReference voltage U given by amplitude limiting adjustment module 14dcDifferencing, via PI regulated output, the controller 16 gives the initial output torque minimum amplitude limit iminThe difference is made with the PI output value to obtain another output minimum torque amplitude limiting value imedThe minimum torque limiting value is acted on the output torque limiting module 108 through the switch module 107, i under the power generation statemedAnd gradually increasing to zero to enable the output torque to be close to zero, the motor does not work in the II th quadrant any more, the part of energy is converted into mechanical energy of a mechanical system, and the rotating speed of the motor is increased.
In step S08, the rotation speed sampling module 17 samples the obtained motor rotation speed nrelGreater than the maximum allowable motor speed n given by the amplitude limiting adjustment module 14maxThe motor operates in an overspeed condition. Motor speed nrelMaximum allowable motor speed n given by amplitude limiting adjustment module 14maxWhen the difference is smaller than 0, the switch module 107 is turned off, the output torque amplitude limiting module 108 recovers the minimum output torque amplitude limiting value, the motor normally operates in the vector control module 101, enters a power generation state, and the rotating speed is reduced. As long as the frequency converter DC bus voltage UdLess than the maximum allowable voltage U given by the overvoltage regulation module 15maxThe frequency converter works in a balanced state of motor speed limit and direct current bus voltage limit.
In step S06, the dc bus voltage U of the inverterdGreater than the maximum allowable voltage U given by the overvoltage regulation module 15maxWhen the direct current bus is in overvoltage, the overvoltage adjusting module 15 outputs a PWM signal to act on the power device J, the braking unit 12 is conducted, the braking resistor R consumes energy, and the situation that the power device and the filter capacitor of the main circuit are damaged due to overhigh voltage of the direct current bus is avoided.
Claims (2)
1. The utility model provides a beam-pumping unit converter with braking voltage restriction which characterized in that: main circuit package of pumping unit frequency converterThe device comprises a three-phase uncontrolled rectifying module (11), a braking unit (12), a voltage sampling module (13), an amplitude limiting adjusting module (14), an overvoltage adjusting module (15), a controller (16), a rotating speed adopting module (17), filter capacitors (C1-C4) and a three-phase inversion module (18); the voltage sampling module (13) detects the direct-current bus voltage of the frequency converter, the rotating speed sampling module (17) detects the rotating speed of the motor, and the amplitude limiting adjustment module (14) obtains the direct-current bus voltage U according to samplingdAnd motor speed nrefOutputting a minimum torque amplitude limit value imedAnd the controller (16) outputs a control signal to act on the three-phase inversion module (18), and the three-phase inversion module (18) controls the motor M.
2. The frequency converter of a pumping unit according to claim 1, wherein: the amplitude limiting adjustment module (14) comprises a PI (proportional integral) adjustment module and a switch module, wherein the PI adjustment module is used for sampling the direct-current bus voltage U sampled by the voltage sampling module (13)dWith a given reference voltage UdcPerforming difference, and outputting a minimum torque amplitude limit value through PI regulation; the switch module is used for controlling the rotating speed of the motor and preventing the rotating speed of the motor from exceeding a certain maximum allowable value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922371955.9U CN212183441U (en) | 2019-12-25 | 2019-12-25 | Pumping unit frequency converter with brake voltage limitation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922371955.9U CN212183441U (en) | 2019-12-25 | 2019-12-25 | Pumping unit frequency converter with brake voltage limitation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212183441U true CN212183441U (en) | 2020-12-18 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201922371955.9U Expired - Fee Related CN212183441U (en) | 2019-12-25 | 2019-12-25 | Pumping unit frequency converter with brake voltage limitation |
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| CN (1) | CN212183441U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114069573A (en) * | 2021-11-05 | 2022-02-18 | 青岛海信日立空调***有限公司 | Air conditioner |
| CN115498937A (en) * | 2022-08-03 | 2022-12-20 | 浙江大学 | Motor rapid shutdown control system and method with novel protection function |
-
2019
- 2019-12-25 CN CN201922371955.9U patent/CN212183441U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114069573A (en) * | 2021-11-05 | 2022-02-18 | 青岛海信日立空调***有限公司 | Air conditioner |
| CN114069573B (en) * | 2021-11-05 | 2024-03-01 | 青岛海信日立空调***有限公司 | Air conditioner |
| CN115498937A (en) * | 2022-08-03 | 2022-12-20 | 浙江大学 | Motor rapid shutdown control system and method with novel protection function |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20201218 Termination date: 20211225 |
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| CF01 | Termination of patent right due to non-payment of annual fee |