CN113533836A - Circuit for monitoring current of electromagnet, current monitoring method and vehicle - Google Patents
Circuit for monitoring current of electromagnet, current monitoring method and vehicle Download PDFInfo
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- CN113533836A CN113533836A CN202010293283.9A CN202010293283A CN113533836A CN 113533836 A CN113533836 A CN 113533836A CN 202010293283 A CN202010293283 A CN 202010293283A CN 113533836 A CN113533836 A CN 113533836A
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- electromagnet
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- Magnetically Actuated Valves (AREA)
Abstract
The invention provides a circuit for realizing current monitoring of an electromagnet. The electromagnet comprises an electromagnet resistor and an inductor connected in series with the electromagnet resistor. The electromagnet includes a first end connected to a first power source and a second end connected to a vehicle control unit. The vehicle control unit comprises a field effect tube, a first resistor, a driving module and a microprocessor, wherein one end of the first resistor is connected with the field effect tube, the other end of the first resistor is grounded, the driving module is used for controlling the field effect tube to be opened and closed, and the microprocessor is connected with the driving module. The driving module is also used for measuring the voltage at two ends of the first resistor and sending a voltage signal to the microprocessor. The other end of the field effect tube is connected with the second end of the electromagnet. And a branch circuit connected with a second voltage is arranged between the second end part and the field effect transistor, and a diode pointing to a second power supply is arranged on the branch circuit. The circuit of the invention can realize the monitoring of the current of the electromagnet.
Description
Technical Field
The invention relates to a circuit for realizing current monitoring of an electromagnet, a current monitoring method and a vehicle.
Background
For a solenoid valve controlled by PWM (pulse width modulation), the resistance and the inductance will change under the influence of temperature, resulting in the change of the current of the solenoid valve, which cannot realize the precise control of the solenoid.
In the prior art, therefore, there is a need to provide a method for overcoming the above-mentioned drawbacks.
Disclosure of Invention
The invention aims to provide a circuit which can realize accurate control on an electromagnet by monitoring the current of the electromagnet.
According to one aspect of the present invention, a circuit for enabling current monitoring of an electromagnet is provided that includes an electromagnet and a vehicle control unit connected to the electromagnet. The electromagnet comprises an electromagnet resistor and an inductor connected in series with the electromagnet resistor. The electromagnet includes a first end connected to a first power source and a second end connected to a vehicle control unit. The vehicle control unit comprises a field effect tube, a first resistor, a driving module and a microprocessor, wherein one end of the first resistor is connected with the field effect tube, the other end of the first resistor is grounded, the driving module is used for controlling the field effect tube to be opened and closed, and the microprocessor is connected with the driving module. The driving module is also used for measuring the voltage at two ends of the first resistor and sending a voltage signal to the microprocessor. The other end of the field effect tube is connected with the second end of the electromagnet. And a branch circuit connected with a second voltage is arranged between the second end part and the field effect transistor, and a diode pointing to a second power supply is arranged on the branch circuit.
Preferably, the current curve of the circuit comprises a fitting stage, when the field effect tube is opened, the current flowing through the electromagnet is calculated by the fitting method, i is Io [1-e ^ (-t/tau) ], wherein i is the current fitted in the fitting stage, Io is the final stable current in the sampling stage, tau is L/R, and t is the instant time counted from the starting point of each fitting stage.
Preferably, the current curve of the circuit comprises a sampling stage, when the field effect tube is closed, the voltage signals at two ends of the first resistor are sampled through the driving module, and the voltage signals are sent to the microprocessor for processing, so that the current signals flowing through the electromagnet are calculated.
Preferably, the vehicle control unit comprises an output channel for controlling the field effect transistor to be opened and closed, and a second resistor is arranged on the output channel.
Preferably, the current curve of the circuit comprises a sampling phase and a fitting phase which are arranged at intervals, wherein the current of the sampling phase is in an ascending trend, and the current of the fitting phase is in a descending trend.
Preferably, the current profile of the circuit comprises at least two sampling phases and at least two fitting phases, the two sampling phases being of different temporal lengths.
Preferably, the first power supply and the second power supply are connected to a vehicle power supply, and the first power supply and the second power supply have the same voltage.
According to an aspect of the present invention, there is also provided a method for monitoring the current of an electromagnet using the above circuit, including:
controlling the field effect transistor to be closed through the driving module, collecting voltages at two ends of the first resistor, and sending voltage signals to the microprocessor for processing to obtain current in a sampling stage;
the field effect transistor is controlled to be turned on through the driving module, and the current at the stage is obtained through a software method.
According to an aspect of the invention, there is also provided a vehicle comprising the circuit described above.
The circuit provided by the invention can realize the monitoring of the current of the electromagnet.
Drawings
Fig. 1 is a schematic frame diagram of a vehicle of the present invention.
Fig. 2 is a schematic diagram of a circuit for controlling an electromagnet according to the present invention.
Fig. 3 is a graph of the current curve of the present invention.
Detailed Description
Fig. 1 is a simplified frame diagram of a vehicle, which is an electric vehicle. The electric Vehicle includes a differential, a motor, an engine, a clutch provided between the motor and the differential, an electromagnet for controlling the clutch, and a VCU (Vehicle Control Unit) for controlling the electromagnet. The VCU controls the clutch by driving the electromagnet. The clutch is located between the differential and the motor, and when the clutch is meshed, the motor can transmit torque to the differential through the transmission shaft, so that driving is achieved. Through the cooperation of the engine and the motor, the four-wheel drive, the front-wheel drive or the rear-wheel drive of the electric vehicle can be realized.
Referring to fig. 2, the electromagnet includes an inductance L and an electromagnet resistance R3 in series with the inductance L. One end of the electromagnet is connected to a first power supply VBR1 and the other end is connected to the VCU. In this embodiment, one end of the inductor L is directly connected to the first power source VBR1, and one end of the electromagnet resistor R3 is directly connected to the VCU. In other embodiments, the positions of the inductor L and the solenoid resistor R3 may be switched, i.e., one end of the solenoid resistor R3 is directly connected to the first power source VBR1 and one end of the inductor L is directly connected to the VCU.
The vehicle control unit includes a field effect transistor in series with the electromagnet and a first resistor R1. One end of the first resistor R1 is grounded, and the other end is connected with the field effect transistor. The other end of the field effect transistor is connected. The vehicle control unit also comprises a driving module for controlling the field effect transistor to be opened and closed and a microprocessor connected with the driving module. The driving module is used for controlling the opening and closing of the field effect transistor. The driving module realizes on-off control of the field effect transistor through the output channel, and can realize diagnosis of SCB (Short to power), SCG (Short to ground) and OL (Open Loop) of the output channel.
Preferably, the electromagnetic iron resistance R3 is 3 ohms, and the inductance value of the inductor L is 16 millihenries. The peak current was 3A for 500 msec and the continuous current was 1 amp. Since the maximum drive current capability of the drive module is 1.8A, a field effect transistor needs to be added to realize 3A large current drive. The resistance value of R1 in fig. 2 is 10 milliohms with a maximum power of 1 watt. The microprocessor of fig. 2 is a microcontroller that can monitor the current through the electromagnet. And a second resistor R2 is arranged on an output channel of the driving module.
When the output channel in the driving module outputs a high level, the field effect transistor is closed to start working, and the first power supply VBR1 forms a loop to the ground through the electromagnet, the field effect transistor and the first resistor R1. By sampling the voltage signal across the first resistor R1 to the driving module, the driving module will amplify the voltage signal 20 times through the internal amplifier and transmit the amplified voltage signal to the microprocessor. Assuming that the voltage signal received by the microprocessor is V and the resistance of the first resistor R1 is R, we can obtain the current I of the electromagnet as (V/20)/R. Although in this embodiment the driver module achieves a 20 times amplification of the voltage signal, in other embodiments other multiples of amplification may be achieved, such as 15 or 30 times.
When the output channel in the driving module outputs low level, the field effect transistor is disconnected and stops working. When the field effect tube is in an off state, although the hardware cannot sample the load current, the current in the off state is fitted through a software algorithm, and closed-loop control over the electromagnet is realized by utilizing a software FIFO (First Input First Output) mechanism. At this time, the first power VBR1 forms a circuit by the electromagnet and the second power VBR2, and realizes the discharge processing of the inductor L. In the present embodiment, the first power source VBR1 and the second power source VBR2 are connected to the vehicle body power source uniformly, so the voltages of the first power source VBR1 and the second power source VBR2 are the same.
Since the voltage across the first resistor R1 is 0 when the fet stops operating. At this point, the VCU is unable to or passes current through the electromagnet. Monitoring of the current through the electromagnet can be achieved by a software fitting algorithm in fig. 3. Thereby realizing the closed-loop control of the electromagnet.
i＝Io[1-e^(-t/τ)]
Where i is the current fitted in the fitting phase, Io is the final steady current in the sampling phase, τ is L/R, and t is the instantaneous time from the start point of each fitting phase.
In the sampling phase, the field effect transistor is in a closed state. The sampling clock signal is the time for the driving module to collect the voltage at two ends of the first resistor R1 in the sampling stage, and the current can be calculated through the voltage. In the fitting stage, the voltage across the first resistor R1 is not collected by the driver module at the fet port. The current for the fitting phase can be calculated by the above mentioned companies. The invention realizes the accurate control of the electromagnet by monitoring the current of the electromagnet. The invention also obtains the current passing through the electromagnet by a software method so as to save the hardware cost of the circuit.
The invention also provides a method for realizing the current monitoring of the electromagnet by using the circuit, which comprises the following steps:
controlling the field effect transistor to be closed through the driving module, collecting voltages at two ends of the first resistor, and sending voltage signals to the microprocessor for processing to obtain current in a sampling stage;
the field effect transistor is controlled to be turned on through the driving module, and the current at the stage is obtained through a software method. Preferably, the software method is a fitting method, and the current at the phase is the current at the fitting phase.
It will be apparent to those skilled in the art that various modifications and variations can be made to the above-described exemplary embodiments of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Claims (9)
1. A circuit for realizing current monitoring of an electromagnet comprises the electromagnet and a vehicle control unit connected with the electromagnet, and is characterized in that the electromagnet comprises an electromagnet resistor and an inductor connected with the electromagnet resistor in series, the electromagnet comprises a first end part connected with a first power supply and a second end part connected with the vehicle control unit, the vehicle control unit comprises a field effect tube, a first resistor, a driving module and a microprocessor, wherein one end of the first resistor is connected with the field effect tube, the other end of the first resistor is grounded, the driving module is used for controlling the field effect tube to be opened and closed, the microprocessor is connected with the driving module, the driving module is further used for measuring voltage at two ends of the first resistor and sending a voltage signal to the microprocessor, the other end of the field effect tube is connected with the second end part of the electromagnet, a branch circuit connected with second voltage is arranged between the second end part and the field effect tube, and the branch circuit is provided with a diode pointing to the second power supply.
2. The circuit of claim 1, wherein the current curve of the circuit comprises a fitting phase, when the fet is turned on, the current flowing through the electromagnet is calculated by the fitting method, i ═ Io [1-e ^ (-t/τ) ], where i is the current fitted in the fitting phase, Io is the final steady current in the sampling phase, τ ═ L/R, t is the instantaneous time from the start of each fitting phase.
3. The circuit of claim 1, wherein the current profile of the circuit includes a sampling phase in which a voltage signal across the first resistor is sampled by the driver module when the fet is closed and sent to the microprocessor for processing to calculate the current signal through the electromagnet.
4. The circuit according to any one of claims 2 to 3, wherein the vehicle control unit comprises an output channel for controlling the opening and closing of the field effect transistor, and a second resistor is arranged on the output channel.
5. The circuit of claim 1, wherein the current profile of the circuit comprises a sampling phase and a fitting phase which are arranged at intervals, the current of the sampling phase is in an upward trend, and the current of the fitting phase is in a downward trend.
6. The circuit of claim 5, wherein the current profile of the circuit comprises at least two sampling phases and at least two fitting phases, the two sampling phases differing in length of time.
7. The circuit of claim 1, wherein the first power source and the second power source are connected to a uniform vehicle power source, and wherein the first power source and the second power source have the same voltage.
8. A method of implementing current monitoring of an electromagnet using the circuit of any one of claims 1 to 7, comprising:
controlling the field effect transistor to be closed through the driving module, collecting voltages at two ends of the first resistor, and sending voltage signals to the microprocessor for processing to obtain current in a sampling stage;
the field effect transistor is controlled to be turned on through the driving module, and the current at the stage is obtained through a software method.
9. A vehicle, characterized in that it comprises a circuit according to any one of claims 1 to 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010293283.9A CN113533836A (en) | 2020-04-15 | 2020-04-15 | Circuit for monitoring current of electromagnet, current monitoring method and vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010293283.9A CN113533836A (en) | 2020-04-15 | 2020-04-15 | Circuit for monitoring current of electromagnet, current monitoring method and vehicle |
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| CN113533836A true CN113533836A (en) | 2021-10-22 |
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| CN202010293283.9A Pending CN113533836A (en) | 2020-04-15 | 2020-04-15 | Circuit for monitoring current of electromagnet, current monitoring method and vehicle |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH06200963A (en) * | 1993-01-07 | 1994-07-19 | Hitachi Ltd | Control device for electromagnetic brake |
| CN202918229U (en) * | 2012-11-05 | 2013-05-01 | 常州亿盛电子电器有限公司 | Energy saving circuit for dual drive DC motor |
| CN103325523A (en) * | 2013-06-29 | 2013-09-25 | 歌尔声学股份有限公司 | Electromagnet protection circuit |
| CN203858947U (en) * | 2014-05-20 | 2014-10-01 | 常熟开关制造有限公司(原常熟开关厂） | Electromagnet control device |
| CN104465015A (en) * | 2014-11-28 | 2015-03-25 | 上海富山精密机械科技有限公司 | Electromagnet driving circuit for cloth pressing mechanism |
| CN109322067A (en) * | 2018-09-25 | 2019-02-12 | 浙江大学 | A kind of presser foot lifter magnet control system of multi-mode output driving |
| CN110488140A (en) * | 2019-09-20 | 2019-11-22 | 无锡麦道电子科技有限公司 | A kind of electromagnet fault detection circuit device and its detection method |
-
2020
- 2020-04-15 CN CN202010293283.9A patent/CN113533836A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06200963A (en) * | 1993-01-07 | 1994-07-19 | Hitachi Ltd | Control device for electromagnetic brake |
| CN202918229U (en) * | 2012-11-05 | 2013-05-01 | 常州亿盛电子电器有限公司 | Energy saving circuit for dual drive DC motor |
| CN103325523A (en) * | 2013-06-29 | 2013-09-25 | 歌尔声学股份有限公司 | Electromagnet protection circuit |
| CN203858947U (en) * | 2014-05-20 | 2014-10-01 | 常熟开关制造有限公司(原常熟开关厂） | Electromagnet control device |
| CN104465015A (en) * | 2014-11-28 | 2015-03-25 | 上海富山精密机械科技有限公司 | Electromagnet driving circuit for cloth pressing mechanism |
| CN109322067A (en) * | 2018-09-25 | 2019-02-12 | 浙江大学 | A kind of presser foot lifter magnet control system of multi-mode output driving |
| CN110488140A (en) * | 2019-09-20 | 2019-11-22 | 无锡麦道电子科技有限公司 | A kind of electromagnet fault detection circuit device and its detection method |
Non-Patent Citations (1)
| Title |
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| 章新友 等: "《全国普通高等医学院校药学类专业十三五规划教材 物理学》", 中国医药科技出版社, pages: 138 - 139 * |
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