CN108828490B - Unmanned aerial vehicle, electronic speed regulator and sampling current calibration method and system thereof - Google Patents
Unmanned aerial vehicle, electronic speed regulator and sampling current calibration method and system thereof Download PDFInfo
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Abstract
The invention relates to an unmanned aerial vehicle, an electronic speed regulator and a method and a system for calibrating sampling current of the electronic speed regulator. The sampling current calibration system comprises a current sampling circuit, a bandwidth filter and a subtracter; the current sampling circuit is used for collecting three-phase current when the electronic speed regulator works with load and converting the collected three-phase current into sampling voltage; the bandwidth filter is connected with the output end of the current sampling circuit; the bandwidth filter is used for filtering the sampling voltage to extract an offset voltage in the sampling voltage; the subtracter is respectively connected with the output end of the current sampling circuit and the output end of the bandwidth filter; the subtracter is used for subtracting the sampling voltage and the offset voltage to obtain a calibration voltage, so that the three-phase current calibrated by the electronic speed regulator is obtained according to the calibration voltage. The system improves the current sampling precision and avoids the current sampling offset introduced when the electronic speed regulator normally works with a load.
Description
Technical Field
The invention relates to the technical field of unmanned aerial vehicles, in particular to an unmanned aerial vehicle, an electronic speed regulator, and a method and a system for calibrating sampling current of the electronic speed regulator.
Background
Many rotor unmanned aerial vehicle is a type of unmanned aerial vehicle that is common on the market at present, generally includes that three and above screw constitute. The screw is driven by the motor, and the motor is driven by the electronic governor, and the three has constituted unmanned aerial vehicle's driving system. The flight controller sends signals to the electronic speed regulator, and the electronic speed regulator controls the rotating speed of the motor and the propeller according to the flight control signals to provide flight power for the unmanned aerial vehicle. When the electronic speed regulator adopts a vector control mode, the current of 2-3 phases of the motor is generally required to be collected as a control parameter for control. The accuracy of the current sampling value affects the performance of the control system and further affects the overall dynamic performance of the aircraft. Due to the fact that the processing part on the sampling current path, devices such as an operational amplifier and the like have certain voltage bias. That is, when the actual current is zero, the value calculated using the sampling value has a certain deviation. The existing processing method generally achieves the purpose of current calibration by sampling the bias voltage at power-on and subtracting the deviation in subsequent processing.
However, the above method has certain disadvantages, when the electronic device normally works with a load, the temperature of the electronic device is changed in a large range due to the switching and conduction losses of the power part, and the bias voltage calibrated in the front is deviated again due to the fact that the electrical characteristics of the electronic device are changed to a certain extent at different temperatures. In another way, temperature calibration is performed for different temperature values, and compensation is performed at different temperatures. However, this method requires a lot of tests, and the temperature characteristics of different batches of devices are different, which requires a lot of manpower and material resources for calibration in mass production.
Disclosure of Invention
The invention aims to provide an unmanned aerial vehicle, an electronic speed regulator, and a method and a system for calibrating sampling current of the electronic speed regulator. The sampling current calibration method and the system improve the current sampling precision and avoid current sampling offset introduced when the electronic speed regulator normally works with a load.
The embodiment of the invention adopts the following technical scheme:
a sampled current calibration system for an electronic governor, comprising: the device comprises a current sampling circuit, a bandwidth filter and a subtracter; the current sampling circuit is used for collecting three-phase current when the electronic speed regulator works with load and converting the collected three-phase current into sampling voltage; the bandwidth filter is connected with the output end of the current sampling circuit; the bandwidth filter is used for filtering the sampling voltage so as to extract an offset voltage introduced by temperature rise in the sampling voltage; the subtracter is respectively connected with the output end of the current sampling circuit and the output end of the bandwidth filter; the subtracter is used for subtracting the sampling voltage and the offset voltage to obtain a calibration voltage, so that the three-phase current calibrated by the electronic speed regulator is obtained according to the calibration voltage.
In one embodiment, the bandwidth filter comprises a low pass filter; the filter characteristic of the low pass filter is determined according to an error characteristic of the offset voltage to extract the offset voltage.
In one embodiment, the low pass filter is a second order low pass filter.
In one embodiment, the filter characteristic of the low-pass filter is determined according to the following formula:
vin(s) represents the sampled voltage input to the low pass filter; veer2(s) represents the offset voltage obtained by the low-pass filter; s represents a laplace transform where the transfer function is a time domain function of the input and output waveforms.
A method of calibrating a sampled current of an electronic governor, comprising: collecting three-phase current of the electronic speed regulator during on-load work, and converting the collected three-phase current into sampling voltage; filtering the sampling voltage in a bandwidth filtering mode to extract offset voltage introduced by temperature rise in the sampling voltage; subtracting the sampling voltage and the offset voltage to obtain a calibration voltage; and obtaining the three-phase current after the electronic speed regulator is calibrated according to the calibration voltage.
In one embodiment, the filtering the sampled voltage by a bandwidth filtering method includes: determining the bandwidth filtering mode according to the following formula:
vin(s) represents the sampled voltage; veer2(s) represents the offset voltage; s represents a laplace transform where the transfer function is a time domain function of the input and output waveforms.
In one embodiment, before obtaining the calibrated three-phase current of the electronic speed regulator according to the calibration voltage, the method further includes: controlling the input current of each phase of bridge arm of a three-phase full-bridge circuit of the electronic speed regulator to be zero; acquiring output voltage of an operational amplifier unit in a current sampling circuit of each phase of bridge arm and reference voltage input by an input end of the operational amplifier unit; determining the static bias voltage of each phase of bridge arm under the static state according to the output voltage of the operational amplifier unit and the reference voltage input by the input end of the operational amplifier unit; the obtaining of the three-phase current after the electronic speed regulator is calibrated according to the calibration voltage comprises the following steps: and obtaining the three-phase current of the electronic speed regulator after calibration according to the calibration voltage and the static bias voltage.
In one embodiment, the method for controlling the electronic speed regulator includes that the input current of each phase bridge arm of a three-phase full-bridge circuit is zero, and the method includes: and controlling one of the pair of series-connected switching tubes of each phase of bridge arm to be switched on and the other switching tube to be switched off at the same moment.
An electronic governor comprising the sampled current calibration system of any of the above embodiments.
An unmanned aerial vehicle comprises the electronic speed regulator.
A storage medium having a computer program stored thereon; the computer program is adapted to be loaded by a processor and to perform the method of calibrating a sample current as described in any of the embodiments above.
According to the sampling current calibration system of the electronic speed regulator, the current sampling circuit collects the current of each phase of bridge arm in the three-phase full-bridge circuit when the electronic speed regulator works in an on-load mode, and simultaneously converts the collected current into sampling voltage. And filtering the sampled voltage through a bandwidth filter, and extracting offset voltage introduced into a circuit when the electronic speed regulator works in an on-load mode in the sampled voltage. And finally, subtracting the offset voltage from the sampling voltage, and calculating to obtain a calibration voltage, so that the calibrated three-phase current can be calculated according to the calibration voltage. The system can calculate the offset voltage and eliminate the error in the actual sampling value, so that the current sampling precision is improved, and the current sampling offset caused by the offset voltage in the circuit is avoided. Meanwhile, the off-line temperature compensation in charge is not needed, the mass production complexity and the production time are reduced, and the mass production efficiency is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.
Fig. 1 is a block diagram of a structural circuit inside an electronic governor in an embodiment provided by the present invention;
FIG. 2 is an internal circuit diagram of a current sampling module for three-phase current of the electronic governor in an embodiment provided by the present invention;
FIG. 3 is a block diagram of a sample current calibration system of an electronic governor in an embodiment of the present invention;
FIG. 4 is a flow chart of a method of calibrating a sampled current of an electronic governor in an embodiment provided by the present invention;
fig. 5 is a schematic waveform diagram of the current of each phase bridge arm ideally collected in an embodiment of the present invention;
FIG. 6 is a waveform diagram illustrating various stages in current sampling in line bias voltage calibration according to an embodiment of the present invention;
FIG. 7 is a flow chart of a method of calibrating a sampled current of an electronic governor in another embodiment provided by the present invention;
FIG. 8 is a flow chart illustrating the operation of current sampling offset calibration in an embodiment of the present invention.
Detailed Description
In order to make the technical problems solved, technical solutions adopted and technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The electronic speed regulator used on the unmanned aerial vehicle generally adopts a speed sensorless control scheme due to the requirements of high reliability and convenience in installation and maintenance. The vector control scheme is a development trend of the control method of the electronic speed regulator gradually due to the characteristics of small torque pulsation, low noise, good dynamic response and the like of the motor. By adopting the vector control scheme, the current signals of the three-phase bridge arm output by the electronic speed regulator need to be acquired so as to realize the control of the motor, adjust the rotating speed of the motor and further adjust the lift force output by the propeller to complete the adjustment of the posture, the steering, the speed and the like of the unmanned aerial vehicle. In the vector control scheme, a current signal is an important parameter of a control system, and the accuracy of a sampling value directly influences the control precision of the control system.
Fig. 1 shows an internal structure of an electronic governor. The three-phase full-bridge circuit comprises three-phase bridge arms, and each phase of bridge arm comprises an upper bridge switching tube and a lower bridge switching tube. As shown in fig. 1, the upper bridge switch tube includes a switch tube Q1, a switch tube Q2 and a switch tube Q3. The lower bridge switching tube comprises a switching tube Q4, a switching tube Q5 and a switching tube Q6. The main control chip controls the conduction and the closing of each switching tube in the three-phase bridge arm and the conduction duty ratio of each switching tube through driving, so that the current from each phase of bridge arm in the three-phase bridge arm to the motor is controlled. When the electronic speed regulator adopts a vector control mode, the current of the motor is generally required to be collected as a control parameter to control the motor. The accuracy of the current sampling value influences the performance of a control system, and further influences the overall power performance of the airplane.
As shown in fig. 1, the electronic speed regulator includes an output current sampling module for respectively collecting the output current of each phase of the bridge arm. The internal circuit of the output current sampling module is shown in fig. 2, and includes 3 current sampling circuits, each of which is used for collecting the output current of one phase bridge arm. As shown in fig. 2, each current sampling circuit includes a sampling resistor and an operational amplifier and other electronic devices. The electronic devices generate different temperature drift voltages at different temperatures and voltages introduced due to line aging and the like in the electronic circuit, so that the accurate value of current sampling in the electronic speed regulator is influenced, and the accuracy of the system is further influenced when the system is controlled according to the sampled current.
The invention provides a sampling current calibration system of an electronic speed regulator, which is used for calibrating collected three-phase current when the electronic speed regulator works with load so as to obtain the accurate value of the three-phase current input into a motor. As shown in fig. 3, in one embodiment, the sampled current calibration system includes a current sampling circuit 200, a bandwidth filter 300, and a subtractor 400.
The current sampling circuit 200 is used for connecting with each phase of bridge arm in the three-phase full-bridge circuit 100 to collect three-phase current when the electronic speed regulator works with load, and simultaneously convert the collected three-phase current into sampling voltage. The three-phase full-bridge circuit 100 is shown in fig. 1, and the internal circuit structure of the current sampling circuit 200 is shown in fig. 2.
The bandwidth filter 300 is connected to the output terminal of the current sampling circuit 200 to receive the sampled voltage Vin output by the current sampling circuit 200. The bandwidth filter 300 is used to filter the sampled voltage to extract an offset voltage in the sampled voltage. The offset voltage includes a voltage induced by a temperature change, that is, a temperature drift voltage, of an electronic device, such as an operational amplifier device, included in the current sampling circuit 200. Meanwhile, the offset voltage also includes a voltage introduced in the circuit due to line aging or the like. When the electronic speed regulator works in an on-load mode, collected sampling voltages (voltages converted from sampling currents) comprise offset voltages and voltages of three-phase currents. The bandwidth filter 300 according to the embodiment of the present invention may filter the sampled voltage to extract the offset voltage therein.
In one embodiment, the bandwidth filter is a low pass filter. The filter characteristic of the low-pass filter is determined according to the error characteristic of the offset voltage introduced in the current sampling module of the three-phase current of the electronic speed regulator so as to extract the offset voltage. Here, the error characteristic of the offset voltage is that the frequency is low and the frequency does not change much. Specifically, the offset voltage is a temperature drift voltage. The error characteristic of the temperature drift voltage is that the temperature drift voltage changes slowly along with the rise of the temperature, and the frequency of the temperature drift voltage is lower. The filter band of the low-pass filter is determined according to the frequency characteristic of the offset voltage. Wherein the low pass filter may be a second order low pass filter. The filter characteristics are determined according to the following formula:
vin(s) represents the sampled voltage input to the low pass filter; veer2(s) represents the offset voltage obtained by the low-pass filter; s represents a laplace transform where the transfer function is a time domain function of the input and output waveforms.
According to the formula, after the three-phase current of the three-phase full-bridge circuit is collected in real time and converted into real-time sampling voltage, the offset voltage can be calculated in real time. In the present embodiment, the offset voltage mainly refers to a temperature drift voltage introduced in the circuit due to a temperature rise. The temperature drift voltage characteristic is determined according to the formula.
The subtractor 400 is respectively connected to the output terminal of the current sampling circuit 200 and the output terminal of the bandwidth filter 300 to receive the sampling voltage Vin output by the current sampling circuit 200 and the offset voltage Veer2 output by the bandwidth filter 300. The subtracter 400 is configured to subtract the sampled voltage Vin and the offset voltage Veer2 to obtain a calibration voltage Vs, so as to obtain a three-phase current calibrated by the electronic speed regulator according to the calibration voltage Vs.
According to the sampling current calibration system of the electronic speed regulator, the current sampling circuit collects the current of each phase of bridge arm in the three-phase full-bridge circuit when the electronic speed regulator works in an on-load mode, and simultaneously converts the collected current into sampling voltage. And filtering the sampling voltage by a bandwidth filter to extract an offset voltage in the sampling voltage. And finally, subtracting the offset voltage from the sampling voltage, and calculating to obtain a calibration voltage, so that the calibrated three-phase current can be calculated according to the calibration voltage. The system can calculate the offset voltage and eliminate the error in the actual sampling value, so that the current sampling precision is improved, and the current sampling offset caused by the offset voltage is avoided. Meanwhile, the off-line temperature compensation in charge is not needed, the mass production complexity and the production time are reduced, and the mass production efficiency is improved.
The invention also provides a method for calibrating the sampling current of the electronic speed regulator, which is used for calibrating the sampling current of the electronic speed regulator to obtain the accurate three-phase current in work. In one embodiment, as shown in fig. 4, the sampling current calibration method includes the following steps:
and S100, collecting three-phase current of the electronic speed regulator during on-load work, and converting the collected three-phase current into sampling voltage.
In this embodiment, the current sampling circuit samples the current of each phase of the bridge arm in the three-phase full-bridge circuit. And when the electronic speed regulator works with load, the current sampling circuit collects the current of each phase of bridge arm. The circuit structure of the current sampling circuit is shown in fig. 2. It should be noted that the current sampling circuit is not limited to the circuit configuration shown in fig. 2, and may have other circuit configurations.
And S200, filtering the sampling voltage in a bandwidth filtering mode to extract the offset voltage in the sampling voltage.
When the electronic speed regulator works normally under load, the sampled voltage contains the voltage corresponding to the three-phase current actually input to the three-phase circuit and additionally increases offset voltage due to various reasons in the circuit, such as line aging, temperature drift characteristics of electronic devices and the like, so that the acquired sampled voltage has errors. In this embodiment, the offset voltage in the sampling voltage is extracted by means of bandwidth filtering.
In one embodiment, the offset voltage comprises a temperature drift voltage due to temperature changes. In particular, the electronic governor can vary over a wide temperature range due to switching losses, conduction losses of the power devices, and losses of the associated power supply circuitry. Since the electrical characteristics of the electronic device are affected by temperature, a slowly changing temperature drift voltage is superimposed on the real sampled current signal when the temperature changes. If the temperature drift voltage is not calibrated and eliminated, errors can be generated in current sampling, and therefore the performance of a control system is affected.
In the vector control scheme of the electronic governor, the current collected for each phase of the bridge arm is ideally a sine wave, as shown in fig. 5. When there is no offset voltage influence, its direct current component approaches 0. When there is an offset voltage effect, it is equivalent to superimposing a slowly varying offset voltage on the fundamental frequency of the current sine wave. In drone applications, the fundamental frequency of the current typically varies within 100Hz-1000 Hz. The change of the offset voltage is slow, and the offset voltage which is superposed in the normal fundamental wave frequency and changes slowly can be calibrated in real time through a certain form of bandwidth filter, so that the influence of factors such as temperature change and the like on current sampling is eliminated.
In this embodiment, a sampling voltage obtained by converting a three-phase current collected when the electronic governor is in an on-load operation is filtered by a bandwidth filter, and an offset voltage in the sampling voltage is extracted. The bandwidth filter selects a low-pass filter of a certain frequency band according to the characteristic of the offset voltage. The frequency band of the filter is determined according to the frequency of the offset voltage. The bandwidth filter is determined according to the formula:
vin(s) represents the sampled voltage; veer2(s) represents the offset voltage; s represents a laplace transform where the transfer function is a time domain function of the input and output waveforms.
In the embodiment of the present embodiment, the offset voltage mainly refers to a temperature drift voltage induced by the temperature drift characteristics of the electronic devices in the circuit.
And S300, subtracting the sampling voltage and the offset voltage to obtain a calibration voltage.
According to the scheme, after the sampling voltage is filtered and extracted to be the offset voltage, the sampling voltage is calibrated according to the offset voltage. Specifically, the offset voltage is subtracted from the sampling voltage to obtain a calibration voltage. In a specific embodiment, the real-time three-phase current is collected on line in real time, and is converted into a real-time sampled voltage by a current sampling circuit as shown in fig. 2. Therefore, the offset voltage obtained according to step S200 is also a real-time offset voltage. And subtracting the real-time sampling voltage from the real-time offset voltage to obtain a real-time calibration voltage.
And S400, obtaining the three-phase current after the electronic speed regulator is calibrated according to the calibration voltage.
After the calibration voltage is obtained through steps S100 to 300, the calibrated three-phase current may be calculated according to the calibration voltage. The specific calculation method can be calculated according to the conversion relationship between the sampling current and the sampling voltage in the current sampling circuit shown in fig. 2.
The scheme adopts a bandwidth filtering mode, calculates the offset voltage and eliminates the error in an actual sampling value. Specifically, the offset voltage includes a temperature drift voltage. The characteristic that the temperature changes slowly is utilized in the scheme, and the temperature drift voltage introduced by the temperature drift characteristic of an electronic device during the on-load work of the electronic speed regulator is filtered, so that the current sampling precision is improved, and the current sampling offset caused by the temperature drift is avoided. Meanwhile, complex off-line temperature compensation is not needed, the mass production complexity and the production time are reduced, and the mass production efficiency is improved.
As shown in fig. 6, the top graph of the graph shows a 100Hz current sampling waveform with a slowly varying offset voltage superimposed, which causes the sampled current to shift from an initial 1.00 and-1.00 peak to a final 1.05 and-0.95 valley. The invention extracts the slowly-changing offset voltage in a bandwidth filtering mode, namely, the offset voltage is calculated on line to obtain the waveform shown in the middle graph in the graph. The lower of the figures is: and subtracting the waveform obtained in the middle graph waveform from the upper graph waveform. It can be seen that the peak to valley values were always 1.00 and-1.00. Therefore, offset is not generated due to the offset voltage, the accuracy of current sampling is improved, and the control performance of a control system is improved. It should be noted that, in the embodiment corresponding to fig. 6, the offset voltage mainly refers to the temperature drift voltage introduced due to the temperature increase.
In an embodiment, as shown in fig. 7, before step S400, the method further includes:
and S10, controlling the input current of each phase bridge arm of the three-phase full-bridge circuit of the electronic speed regulator to be zero.
In the scheme, a main control chip in the electronic speed regulator controls the input current of each phase of bridge arm in the three-phase full-bridge circuit to be zero through driving. Specifically, as shown in fig. 1, the main control chip drives and controls a pair of series-connected switching tubes of each phase of the bridge arm, and at the same time, one of the switching tubes is turned on and the other switching tube is turned off.
And S20, acquiring the output voltage of the operational amplifier unit in the current sampling circuit of each phase bridge arm and the reference voltage input by the input end of the operational amplifier unit.
As shown in fig. 2, the system can obtain the voltage output by the operational amplifier unit and the reference voltage input by one input terminal of the operational amplifier unit in the current sampling circuit. For example, as shown in fig. 2, the output voltage V1 of the operational amplifier U1 and the reference voltage Vref input to the input terminal thereof, the output voltage V2 of the operational amplifier U2 and the reference voltage Vref input to the input terminal thereof, or the output voltage V1 of the operational amplifier U3 and the reference voltage Vref input to the input terminal thereof.
And S30, determining the static bias voltage of each phase of bridge arm under the static state according to the output voltage of the operational amplifier unit and the reference voltage input by the input end of the operational amplifier unit.
In the three-phase full-bridge circuit, under the condition that the current of each phase of bridge arm is zero, the static bias voltage of each phase of bridge arm under the static state can be determined according to the output voltage of the operational amplifier unit and the reference voltage input by the input end. For example, as shown in fig. 2, the sampling current is zero, and the output voltage V1 of the operational amplifier U1 and the input reference voltage Vref thereof can be used to determine the static bias voltage generated in the static environment. Similarly, the static bias voltage generated under the static environment determined by the operational amplifier U2 and the operational amplifier U3 can be obtained.
The following provides an embodiment for obtaining the static bias voltage based on the operating environment of the electronic speed regulator:
after the system enters a static bias calibration program, according to the electronic speed regulator structure shown in fig. 1, the main control chip sends out a PWM signal, and the MOSFET in the electronic speed regulator is turned on and off by the driving circuit. Specifically, the main control chip sends out a PWM signal with a duty ratio of 50% according to the switching frequency (generally 10KHz-20 KHz). In this way, MOSFETs of the same arm (switching tube Q1 and switching tube Q4 are a-phase arm, switching tubes Q2 and Q5 are B-phase arm, and switching tube Q3 and switching tube Q6 are C-phase arm) are each turned on by 50%. Because three-phase PWM is sent out simultaneously, under normal conditions, Q1, Q2 and Q3 are turned on and off simultaneously, and Q4, Q5 and Q6 are also turned on and off simultaneously. However, a pair of switching tubes of the same phase arm cannot be simultaneously turned on. It can be seen that the currents flowing through the sampling resistors Rc1, Rc2, Rc3 are all 0. According to the current sampling circuit schematic of fig. 2, each phase of the current sample is given a reference voltage Vref. Since the input differential voltage is 0, the output of each phase op-amp should be Vref calculated from the sampled current of fig. 2. However, due to the fact that certain errors Verr1 are introduced due to resistance value deviation of the resistor and deviation of the operational amplifier circuit, the voltage actually acquired is Vref + Verr 1. And recording the Vref + Verr1 acquired at the moment by the static bias calibration program as a bias voltage in subsequent calculation for error elimination, and improving the sampling precision.
At this time, step S400 includes the steps of:
and S410, obtaining the three-phase current of the electronic speed regulator after calibration according to the calibration voltage and the static bias voltage.
In this embodiment, the three-phase current after the electronic speed regulator is calibrated can be obtained according to the calibration voltage obtained in the dynamic calibration environment and the static bias voltage obtained in the static calibration environment. That is, the embodiment of the present invention adds an online dynamic bias calibration process while using the static current bias calibration. The characteristic of slow temperature change is utilized, and current sampling bias caused by factors such as temperature and the like is eliminated by adopting online bias calibration, so that the aim of real-time calibration is fulfilled, and the accuracy of current sampling is improved.
The invention also provides an electronic speed regulator. The electronic speed regulator comprises the sampling current calibration system and a three-phase full-bridge circuit according to any one of the embodiments. The sampling current calibration system is used for calibrating the sampling current of each phase of bridge arm in the three-phase full-bridge circuit when the electronic speed regulator works in an on-load mode so as to obtain an accurate current sampling value.
The current sampling calibration process of the electronic governor is shown in fig. 8. After the electronic speed regulator receives a starting signal sent by the flight control system, before the motor is started, the electronic speed regulator performs a three-phase current sampling current calibration process as shown in fig. 8. The calibration method of the current sampling static calibration and the current sampling online dynamic calibration is as described in the above embodiments, and will not be described in detail here.
Further, the invention also provides the unmanned aerial vehicle. This unmanned aerial vehicle includes the electron governor of above-mentioned embodiment, still includes flight controller and motor. The flight controller is used for outputting a flight control signal to the electronic speed regulator so that the electronic speed regulator provides flight power for the unmanned aerial vehicle according to the rotating speed of the control motor.
The invention also provides a storage medium. The storage medium having stored thereon a computer program; the computer program, when executed by a processor, implements the method of calibrating a sample current as described in any of the above embodiments. The storage medium may be a memory. For example, internal memory or external memory, or both. The memory may comprise read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or random access memory. The external memory may include a hard disk, a floppy disk, a ZIP disk, a usb-disk, a magnetic tape, etc. The storage media disclosed herein include, but are not limited to, these types of memories. The disclosed memory is by way of example only and not by way of limitation.
The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.
Claims (10)
1. A sampled current calibration system for an electronic governor, comprising: the device comprises a current sampling circuit, a bandwidth filter and a subtracter;
the current sampling circuit is used for collecting three-phase current when the electronic speed regulator works with load and converting the collected three-phase current into sampling voltage; the current sampling circuit comprises a sampling resistor and an operational amplifier unit;
the bandwidth filter is connected with the output end of the current sampling circuit; the bandwidth filter is used for filtering the sampling voltage to extract an offset voltage in the sampling voltage;
the subtracter is respectively connected with the output end of the current sampling circuit and the output end of the bandwidth filter; the subtracter is used for subtracting the sampling voltage and the offset voltage to obtain a calibration voltage so as to obtain a three-phase current after the electronic speed regulator is calibrated according to the calibration voltage;
the system is also used for controlling the input current of each phase of bridge arm of the three-phase full-bridge circuit of the electronic speed regulator to be zero; acquiring output voltage of an operational amplifier unit in a current sampling circuit of each phase of bridge arm and reference voltage input by an input end of the operational amplifier unit; determining the static bias voltage of each phase of bridge arm under the static state according to the output voltage of the operational amplifier unit and the reference voltage input by the input end of the operational amplifier unit; the obtaining of the three-phase current after the electronic speed regulator is calibrated according to the calibration voltage comprises the following steps: and obtaining the three-phase current of the electronic speed regulator after calibration according to the calibration voltage and the static bias voltage.
2. The calibration system of claim 1, wherein the bandwidth filter comprises a low pass filter; the filter characteristic of the low pass filter is determined according to an error characteristic of the offset voltage to extract the offset voltage.
3. The calibration system of claim 2, wherein the low pass filter is a second order low pass filter.
4. The calibration system of claim 2, wherein the filter characteristic of the low pass filter is determined according to the following equation:
vin(s) represents the sampled voltage input to the low pass filter; veer2(s) represents the offset voltage obtained by the low-pass filter; s represents a laplace transform where the transfer function is a time domain function of the input and output waveforms.
5. A method for calibrating a sampling current of an electronic speed regulator is characterized by comprising the following steps:
collecting three-phase current of the electronic speed regulator during on-load work, and converting the collected three-phase current into sampling voltage; the current sampling circuit for collecting the three-phase current comprises a sampling resistor and an operational amplifier unit;
filtering the sampling voltage in a bandwidth filtering mode to extract an offset voltage in the sampling voltage;
subtracting the sampling voltage and the offset voltage to obtain a calibration voltage;
controlling the input current of each phase of bridge arm of a three-phase full-bridge circuit of the electronic speed regulator to be zero;
acquiring output voltage of an operational amplifier unit in a current sampling circuit of each phase of bridge arm and reference voltage input by an input end of the operational amplifier unit;
determining the static bias voltage of each phase of bridge arm under the static state according to the output voltage of the operational amplifier unit and the reference voltage input by the input end of the operational amplifier unit;
and obtaining the three-phase current of the electronic speed regulator after calibration according to the calibration voltage and the static bias voltage.
6. The sampled current calibration method of claim 5, wherein said filtering said sampled voltage by bandwidth filtering comprises: determining the bandwidth filtering mode according to the following formula:
vin(s) represents the sampled voltage; veer2(s) represents the offset voltage; s represents a laplace transform where the transfer function is a time domain function of the input and output waveforms.
7. The sampled current calibration method of claim 5, wherein the controlling the input current of each phase leg of the three-phase full bridge circuit of the electronic speed regulator to be zero comprises:
and controlling one of the pair of series-connected switching tubes of each phase of bridge arm to be switched on and the other switching tube to be switched off at the same moment.
8. An electronic governor comprising the sampled current calibration system of any of claims 1 to 4.
9. An unmanned aerial vehicle comprising the electronic governor of claim 8.
10. A computer-readable storage medium, having stored thereon a computer program; the computer program is adapted to be loaded by a processor and to perform the sampling current calibration method of any of the preceding claims 5 to 7.
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