CN109039200B - Efficient excitation control method for electric forklift oil pump motor - Google Patents
Efficient excitation control method for electric forklift oil pump motor Download PDFInfo
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- CN109039200B CN109039200B CN201810964491.XA CN201810964491A CN109039200B CN 109039200 B CN109039200 B CN 109039200B CN 201810964491 A CN201810964491 A CN 201810964491A CN 109039200 B CN109039200 B CN 109039200B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/22—Current control, e.g. using a current control loop
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Forklifts And Lifting Vehicles (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The invention discloses a high-efficiency excitation control method for an oil pump motor of an electric forklift, which comprises the following steps of: step one, calculating the iron loss of a motor; step two, calculating the copper loss of the motor; step three, calculating the total loss according to the iron loss and the copper loss of the motor obtained in the step one and the step two; calculating the corresponding relation between the exciting current and the torque current when the total loss is minimum under the condition that the load torque is not changed; step five, calculating the exciting current; the invention obtains the corresponding relation between the global loss and the currents of the exciting current and the torque by taking the iron loss into account on the basis of the traditional loss analysis mode only considering the copper loss, and finally obtains the high-efficiency excitation control method for the oil pump motor of the electric forklift with the minimum global loss.
Description
Technical Field
The invention relates to the technical field of motor control, in particular to a high-efficiency excitation control method for an oil pump motor of an electric forklift.
Background
The oil pump motor for the electric forklift is usually an induction motor, operates in a constant torque area and a constant power area, and meanwhile, the load torque changes greatly under different working conditions. In induction vector control, the electromagnetic torque is proportional to the product of the field current and the torque current, meaning that there will be a variety of different field and torque current combinations that produce the same electromagnetic torque.
The loss of the motor during operation comprises copper loss and iron loss, and under the condition that the material and the process of the motor are the same, the loss of the motor is related to rotating speed, exciting current and torque. Under the condition of the same rotating speed and the same load torque, the losses generated by different exciting current and torque current combinations are different. In vector control, when the motor is in a constant torque stage, the conventional control method of the exciting current keeps a rated value so as to obtain the fastest response speed. I.e. the excitation current is constant regardless of the load torque variation. At this time, motor losses are not minimal.
Because the electric fork-lift truck is the energy limiting system of battery power supply, therefore motor work efficiency is crucial. At present, the conventional excitation current optimal analysis only comprises copper loss analysis, namely ohmic loss, and the current excitation current can be obtained by calculation according to stator resistance and rotor resistance. The motor efficiency obtained by using the conventional excitation current control method is not the highest because the iron loss of the motor is not considered. How to obtain a global efficient excitation control method is a difficult point and a key point of electric forklift motor control.
Disclosure of Invention
The invention aims to provide an efficient excitation control method for an oil pump motor of an electric forklift, which can obtain a corresponding relation between overall loss and excitation current and torque current by taking iron loss into consideration, and can calculate the excitation current of an induction motor in real time to obtain the minimum overall loss according to the magnitude of electromagnetic torque at the moment, so as to solve the problems in the background art.
In order to achieve the purpose, the invention provides the following technical scheme:
a high-efficiency excitation control method for an oil pump motor of an electric forklift comprises the following steps:
step one, calculating the iron loss of a motor;
step two, calculating the copper loss of the motor;
step three, calculating total loss according to the iron loss and the copper loss of the motor obtained in the step one and the step two;
calculating the corresponding relation between the exciting current and the torque current when the total loss is minimum under the condition that the load torque is not changed;
and step five, calculating the exciting current in real time according to the electromagnetic torque according to the corresponding relation between the exciting current and the torque current when the total loss is minimum, and then synchronizing the calculated exciting current with the exciting current of the induction motor.
As a further scheme of the invention: the formula for calculating the copper loss of the motor in the first step is as follows:
as a further scheme of the invention: and the formula for calculating the iron loss of the motor in the step two is as follows:
as a further scheme of the invention: the formula for calculating the total loss in the third step is as follows:
as a further scheme of the invention: in the fourth step, when the load torque is not changed, the corresponding relation between the exciting current and the torque current when the total loss is minimum is obtained as follows:
as a further scheme of the invention: in the fourth step, the degradation of the corresponding relation between the exciting current and the torque current when the total loss is minimum is obtained as a relation capable of calculating a numerical solution on line under the condition that the load torque is not changed, and the specific method comprises the following steps:
step 1, simplifying a corresponding relation between exciting current and torque current into:
step 2, calculating by adopting an iteration mode:
step (1):
step (2):
compared with the prior art, the invention has the beneficial effects that: the invention has the following advantages: firstly, the iron loss of the motor is considered during calculation; secondly, the total loss can be minimized; thirdly, the exciting current can be calculated in real time; fourthly, the operation time of the electric forklift is improved; fifthly, hardware design is not changed, and cost is low.
Detailed Description
The technical solution of the present patent will be described in further detail with reference to the following embodiments.
A high-efficiency excitation control method for an oil pump motor of an electric forklift comprises the following steps:
step one, calculating the iron loss of a motor;
step two, calculating the copper loss of the motor;
step three, calculating the total loss according to the iron loss and the copper loss of the motor obtained in the step one and the step two;
step four, calculating the corresponding relation between the exciting current and the torque current when the total loss is minimum under the condition that the load torque is not changed;
and step five, calculating the exciting current in real time according to the electromagnetic torque according to the corresponding relation between the exciting current and the torque current when the total loss is minimum, and then synchronizing the calculated exciting current with the exciting current of the induction motor.
The formula for calculating the copper loss of the motor in the first step is as follows:
the formula for calculating the iron loss of the motor in the second step is as follows:
the formula for calculating the total loss in the third step is as follows:
in the fourth step, when the load torque is not changed, the corresponding relation between the exciting current and the torque current when the total loss is minimum is as follows:
this expression can be further simplified as:
and (3) calculating by adopting an iteration mode:
step 1:
step 2:
the working principle of the invention is as follows: on the basis of a traditional loss analysis mode only considering copper loss, the iron loss is simultaneously considered, and the corresponding relation between the global loss and the currents of the exciting current and the torque is obtained. Under the condition of a certain rotating speed, the corresponding relation is a high-order equation, the numerical solution cannot be calculated on line, and the order reduction processing needs to be carried out on the numerical solution. According to the reduced relational expression and the electromagnetic torque at the moment, the exciting current of the induction motor can be calculated in real time, and finally the excitation control method with the minimum global loss is obtained.
Although the preferred embodiments of the present patent have been described in detail, the present patent is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present patent within the knowledge of those skilled in the art.
Claims (4)
1. A high-efficiency excitation control method for an oil pump motor of an electric forklift is characterized by comprising the following steps:
step one, calculating the iron loss of a motor;
step two, calculating the copper loss of the motor;
step three, calculating total loss according to the iron loss and the copper loss of the motor obtained in the step one and the step two;
calculating the corresponding relation between the exciting current and the torque current when the total loss is minimum under the condition that the load torque is not changed;
step five, calculating exciting current in real time according to the corresponding relation between the exciting current and the torque current when the total loss is minimum and the size of the electromagnetic torque, and then synchronizing the calculated exciting current with the exciting current of the induction motor;
the formula for calculating the iron loss of the motor in the first step is as follows:
in the fourth step, the corresponding relation between the exciting current and the torque current when the total loss is minimum is obtained under the condition that the load torque is not changed, and the corresponding relation is as follows:
2. the efficient excitation control method for the oil pump motor of the electric forklift truck as recited in claim 1, wherein the formula for calculating the copper loss of the motor in the second step is as follows:
3. the efficient excitation control method for the oil pump motor of the electric forklift as recited in claim 1, wherein the formula for calculating the total loss in the third step is as follows:
4. the efficient excitation control method for the oil pump motor of the electric forklift as recited in claim 1, wherein the step four obtains the degradation of the corresponding relation between the exciting current and the torque current when the total loss is minimum under the condition that the load torque is not changed into a relation capable of calculating a numerical solution on line, and the specific method comprises the following steps:
step 1, simplifying a corresponding relation between exciting current and torque current into:
step 2, calculating by adopting an iteration mode:
step (1):
step (2):
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| CN201810964491.XA CN109039200B (en) | 2018-08-23 | 2018-08-23 | Efficient excitation control method for electric forklift oil pump motor |
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| CN201810964491.XA CN109039200B (en) | 2018-08-23 | 2018-08-23 | Efficient excitation control method for electric forklift oil pump motor |
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| CN109039200B true CN109039200B (en) | 2022-05-24 |
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| CN112422018A (en) * | 2020-11-03 | 2021-02-26 | 睿驰电装(大连)电动系统有限公司 | Electric drive system efficiency calibration method and device and electric automobile |
| CN115425883B (en) * | 2022-11-07 | 2023-01-17 | 南京师范大学 | Electric excitation double salient pole power generation method based on hierarchical optimization and overvoltage protection |
| CN116620042B (en) * | 2023-06-05 | 2024-02-06 | 小米汽车科技有限公司 | Motor control parameter calibration method and device and vehicle |
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| CN105071735A (en) * | 2015-07-31 | 2015-11-18 | 西安理工大学 | Energy-saving control method of asynchronous motor based on T-1 simplified model |
| CN105634357A (en) * | 2016-01-25 | 2016-06-01 | 华中科技大学 | Efficiency optimization control method for linear induction motor |
| CN106685299A (en) * | 2015-11-04 | 2017-05-17 | 湖南大学 | Current control method of built-in PMSM (Permanent Magnet Synchronous Motor) |
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|---|---|---|---|---|
| CN105071735A (en) * | 2015-07-31 | 2015-11-18 | 西安理工大学 | Energy-saving control method of asynchronous motor based on T-1 simplified model |
| CN106685299A (en) * | 2015-11-04 | 2017-05-17 | 湖南大学 | Current control method of built-in PMSM (Permanent Magnet Synchronous Motor) |
| CN105634357A (en) * | 2016-01-25 | 2016-06-01 | 华中科技大学 | Efficiency optimization control method for linear induction motor |
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| 异步电动机控制系统的效率优化研究;张晓丽;《中国优秀硕士学位论文全文数据库（工程科技Ⅱ辑）》;20170315;第23-27、33-35页 * |
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