Non-inductive square wave controlled back electromotive force sampling mechanism and control system

Abstract

The invention discloses a non-inductive square wave controlled back electromotive force sampling mechanism and a control system, and relates to the technical field of motor control, the non-inductive square wave controlled back electromotive force sampling mechanism comprises an ADC module of a multi-channel comprehensive trigger mechanism. The method comprises the steps that an ADC module is triggered by an ADC first trigger source for the first time to sample bus voltage and suspended phase end voltage of a to-be-sampled motor, and a first voltage value of the bus voltage and a second voltage value of the suspended phase end voltage are obtained; if yes, an ADC module is triggered by an ADC second trigger source to perform at least one time of repeated sampling on the suspended phase terminal voltage, and a second zero crossing point of the back electromotive force is detected until second remaining time of the effective signal after repeated sampling is smaller than sampling time of the ADC module. According to the invention, the sampling consumption time is shortened, and the precision of counter electromotive force zero crossing point detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a back electromotive force sampling mechanism and a control system for non-inductive square wave control. Background Art

[0002] In the sensorless square wave control of a brushless direct current motor (BLDC), the back electromotive force of the motor is usually collected as the key input of the zero-point commutation algorithm. The zero-point commutation algorithm is a control algorithm in BLDC control. The rotor position is determined by detecting the terminal voltage of the three phases of the BLDC motor and judging the zero-point by the terminal voltage. The rotation speed of the brushless motor can be adjusted by controlling the current according to the rotor position. The three-phase terminal voltage of the BLDC is detected, and then the back electromotive force zero-point judgment is performed. That is, each zero-point detection requires the collection of three analog data of the three-phase terminals, and the sampling consumes a long time. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, one object of the present invention is to propose a back electromotive force sampling mechanism and control system with non-inductive square wave control to shorten the sampling time.

[0004] According to a first aspect of an embodiment of the present invention, a back electromotive force sampling mechanism for non-inductive square wave control is provided, the sampling mechanism comprising: In each PWM (Pulse-Width Modulation, pulse width modulation technology) control cycle of the motor to be sampled, triggering an analog-to-digital converter ADC module (Analog-to-Digital Converter, analog-to-digital converter) for the first time through an ADC first trigger source to sample the bus voltage and the suspended phase terminal voltage of the motor to be sampled, so as to obtain a first voltage value of the bus voltage and a second voltage value of the suspended phase terminal voltage; Detecting a first zero-crossing point of a back electromotive force based on the first voltage value and the second voltage value, and determining a first remaining time of a valid signal within the PWM control period; If the first remaining time is greater than or equal to the sampling time of the ADC module, the ADC module is triggered by the ADC second trigger source to repeatedly sample the floating phase terminal voltage at least once to obtain a third voltage value of the floating phase terminal voltage, and the second zero crossing point of the back electromotive force is detected according to the first voltage value, the third voltage value and the third voltage value, until the second remaining time of the valid signal after repeated sampling is less than the sampling time of the ADC module.

[0005] Optionally, the ADC module is configured with a multi-channel integrated trigger mechanism, which includes at least two trigger sources, including the ADC first trigger source and the ADC second trigger source, the first trigger source is the update event trigger source of the PWM timing module; the second trigger source is a software trigger source.

[0006] Optionally, in the multi-channel integrated trigger mechanism, any trigger source is configured to enable one or more sampling channels of the ADC module.

[0007] Optionally, the triggering analog-to-digital converter ADC module samples the bus voltage and the suspended phase terminal voltage of the motor to be sampled, including: When the ADC first trigger source is configured to enable multiple target sampling channels, the ADC module is triggered to sample the target sampling channels in sequence, and the target sampling channels include sampling channels corresponding to the bus voltage and the floating phase terminal voltage.

[0008] Optionally, the ADC first trigger source includes at least one of the following: Timer and event output module.

[0009] Optionally, the ADC second trigger source is configured to have the following trigger conditions: Triggered when the preset controller program runs to the program target position.

[0010] Optionally, detecting a first zero-crossing point of a back electromotive force based on the first voltage value and the second voltage value includes: If the second voltage value is half of the first voltage value, the time point at which the second voltage value is collected is the first zero-crossing point.

[0011] According to a second aspect of an embodiment of the present invention, there is provided a back electromotive force sampling control system with non-inductive square wave control, the control system comprising: a three-phase half-bridge drive circuit, a micro control unit MCU; The MCU is used to store a computer program, wherein the computer program is configured as the back electromotive force sampling mechanism of the non-inductive square wave control described in any one of the above items to determine the zero-crossing point of the back electromotive force; The three-phase half-bridge driving circuit is used to control the commutation operation of the motor to be sampled based on the determined zero-crossing point.

[0012] In the solution provided by the embodiment of the present invention, according to the solution provided by the embodiment of the present invention, only the bus voltage and the floating phase terminal voltage need to be collected in each PWM control cycle, and the obtained voltage value can be used for zero-crossing detection, and there is no need to collect all the three-phase terminal voltages. Only two data need to be collected at most for each detection, and the first voltage value of the bus voltage only needs to be collected once, which reduces the number of sampling channels of the required ADC module and shortens the time consumed by sampling, so that the zero-crossing point can be detected more quickly, thereby improving the efficiency of subsequent motor control and the commutation detection accuracy of the inductive square wave algorithm.

[0013] Furthermore, by using the first ADC trigger source and the second ADC trigger source in combination, it is possible to try to detect the zero-crossing point as many times as possible within a PWM control cycle when the sampling time of the ADC allows, and the detection accuracy can also be improved.

[0014] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of a back electromotive force sampling mechanism provided by an embodiment of the present invention; Figure 2 It is a level waveform diagram of a PWM control period provided by an embodiment of the present invention; Figure 3 is a schematic structural diagram of a first BLDC provided by an embodiment of the present invention; Figure 4 is a schematic structural diagram of a second BLDC provided by an embodiment of the present invention; Figure 5 is a voltage waveform diagram of the first BLDC provided by an embodiment of the present invention; Figure 6 is a voltage waveform diagram of the second BLDC provided by an embodiment of the present invention; Figure 7 It is a structural diagram of a multi-channel integrated trigger mechanism of an ADC module provided by an embodiment of the present invention; Figure 8 It is a schematic diagram of the control system structure of the sensorless square wave control provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0017] The following describes the back electromotive force sampling mechanism and control system of the non-inductive square wave control according to the embodiments of the present invention with reference to the accompanying drawings.

[0018] In one embodiment of the present invention, see Figure 1 , a back electromotive force sampling mechanism for non-inductive square wave control is provided, including the following method steps S101-S103.

[0019] S101: In each PWM control cycle of the motor to be sampled, triggering the analog-to-digital converter ADC module for the first time through the ADC first trigger source to sample the bus voltage and the suspended phase terminal voltage of the motor to be sampled, and obtaining a first voltage value of the bus voltage and a second voltage value of the suspended phase terminal voltage; S102: Detecting a first zero-crossing point of a back electromotive force based on the first voltage value and the second voltage value, and determining a first remaining time of a valid signal within the PWM control period; S103: If the first remaining time is greater than or equal to the sampling time of the ADC module, the ADC module is triggered by the ADC second trigger source to repeat sampling of the floating phase terminal voltage at least once to obtain a third voltage value of the floating phase terminal voltage, and the second zero-crossing point of the back electromotive force is detected according to the first voltage value, the third voltage value and the third voltage value, until the second remaining time of the valid signal after repeated sampling is less than the sampling time of the ADC module.

[0020] PWM (Pulse-Width Modulation) refers to pulse width modulation technology, which is an equivalent modulation method for signal output. Common parameters are carrier frequency, duty cycle, period, etc. Assuming that the carrier frequency of a PWM is 10kHz, the corresponding PWM control period is 100μs. In one PWM period, the power switch of the motor to be sampled realizes one switching cycle, thereby controlling the speed and torque of the motor.

[0021] The motor has a stator core and a permanent magnet rotor. There is a stator winding on the stator core. When voltage is applied to the stator winding and a certain current is passed through the stator winding, the corresponding electromagnetic torque can be generated, thereby driving the rotor to rotate. For square wave control, there are 6 common voltage vectors with different angles. The correct voltage vector needs to be selected according to the rotor position to drag the rotor to rotate in the desired direction. Therefore, certain means are required to obtain the rotor position information. Zero-crossing commutation is a non-sensing square wave control algorithm.

[0022] A signal with a duty cycle in a PWM control cycle is the actual effective output, that is, in the switching cycle, the on corresponds to a high level and the off corresponds to a low level. The time of the effective signal is the high level time, such as Figure 2The time represented by PWM_ON in FIG. As can be seen from the figure, in one PWM control cycle, one switching operation is performed.

[0023] In the above embodiment, the motor to be sampled is a brushless DC motor BLDC. The BLDC drive circuit is a three-phase half-bridge drive circuit, such as Figure 3 As shown in the figure, components 1, 2, and 3 represent the upper bridge MOS (MOSFET, metal-oxide semiconductor field effect transistor) of BLDC, and components 4, 5, and 6 represent the lower bridge MOS of BLDC.

[0024] The U, V, and W lines connect the three phases of the BLDC. By conducting the stator windings of two phases (one phase on the upper bridge and one phase off the lower bridge), a voltage vector is output to drive the rotor to rotate, and the phase that is not conducted is a suspended phase.

[0025] For example, in Figure 3 In the example, the MOS drive signal can be given to component 3 to connect the positive pole of the power supply and the W phase of the motor, and the MOS drive signal can be given to component 5 to connect the negative pole of the power supply and the V phase of the motor. The MOS tube is a switching device that connects the winding and the power supply. The waveform diagram of W+V- is as follows: Figure 5 Sector 1 is shown. Sector 1-6 indicates the conditions of different phases being turned on when the motor rotates one circle, which are U+V-, U+W-, V+W-, V+U-, W+U-, respectively. The plus sign indicates that the positive pole is turned on, and the minus sign indicates that the negative pole is turned on. The three groups of waveforms show the voltage changes of the three phases U, V, and W.

[0026] exist Figure 3 In the circuit diagram, a diode is also set on the right side of the MOS tube of each phase. The existence of the diode is to protect the circuit. When the MOS tube is suddenly turned off, but there is still current in the winding of the motor. Since the winding of the motor is essentially an inductor, the current cannot change suddenly and needs to be released by the loop. Therefore, the existence of the diode can slowly reduce the current in the motor.

[0027] In motor control, the motor stator voltage needs to be 90° different from the rotor position to generate the maximum electromagnetic torque. Therefore, the motor rotor position needs to be determined to determine the output voltage vector.

[0028] By detecting the zero-crossing moment of the back electromotive force of the suspended phase, the BLDC rotor position can be determined, thereby adjusting the rotation speed of the brushless motor.

[0029] 1, 2, 3 components are connected to the positive busbar above, 4, 5, 6 components are connected to the negative busbar below, as shown below: Figure 4 As shown, the first voltage value of the bus voltage is U bus .

[0030] Figure 4The BLDC in the middle is also the motor to be sampled. The W-phase upper bridge MOS and the V-phase lower bridge MOS are turned on, and the U-phase is the suspended phase. For the turned-on MOS tube, the voltage value generated is U mos .

[0031] The sampling process of the ADC (Analog-to-Digital Converter) module is as follows (1)-(5).

[0032] (1) Sampling: The ADC first samples the analog signal, that is, it captures the bus voltage signal at a specific time point. According to the Nyquist sampling theorem, the sampling frequency must be at least twice the highest frequency of the signal to avoid aliasing.

[0033] (2) Hold: After sampling, the ADC will temporarily hold the voltage signal for subsequent quantization processing. This stage is called "sample and hold".

[0034] (3) Quantization: In the quantization stage, the ADC converts the sampled and held voltage signal into discrete digital values.

[0035] (4) Encoding: The quantized discrete levels are converted into binary codes, which are a format that digital systems can understand and process. For example, a 3-bit ADC can quantize discrete digital values ​​into 8 levels and represent them with 3 binary bits (from 000 to 111).

[0036] (5) Output: Finally, the ADC outputs this binary value, which is the first voltage value.

[0037] The method of sampling the suspended phase terminal voltage is the same as the bus voltage sampling. The only difference is whether it is sampling the bus or sampling the suspended phase of the motor to be sampled, which will not be described in detail here.

[0038] When the first voltage value and the second voltage value are obtained, the first zero-crossing point of the back electromotive force can be detected in the following manner: If the second voltage value is half of the first voltage value, the time point at which the second voltage value is collected is the first zero-crossing point.

[0039] by Figure 4 For example, the W phase upper bridge MOS and the V phase lower bridge MOS are turned on, and the U phase is a floating phase. Figure 4 As shown, the bus voltage is U bus , the MOS tube voltage drop is U mos , the actual negative pole voltage of the motor W phase should be U bus -U mos , the actual negative voltage of the motor V phase should be U mos , the reference voltage of phase U zero crossing should be half of the sum of phase W and phase V: (U bus-U mos +U mo s) / 2, that is, U bus / 2. That is to say, the bus voltage can be directly used as the reference level for judging the zero-crossing point of the back electromotive force in the inductive square wave control algorithm.

[0040] If the first zero crossing is detected, the specific control method is as follows: Motor control is to divide the voltage output by the inverter circuit into sectors of 0 to 360°, with each sector being 60°. Inductive square wave control is to output a voltage vector for each sector to drive the motor rotor to rotate. After the first zero crossing is detected, wait for a period of time (theoretically, the time for the motor to rotate 30 degrees electrical angle), and then switch the voltage vector. The square wave algorithm completes the work of switching sectors.

[0041] In the case of a sector every 60°, after updating the voltage vector and entering a new sector, the motor will rotate 30° to reach the position where the back electromotive force is 0. Therefore, after we detect the zero point, the motor needs to rotate another 30° before we switch the voltage vector and enter the next sector. In other words, the moment when the back electromotive force is 0 generally occurs in the middle of a sector, and the voltage vector is switched 6 times in one rotation of the motor.

[0042] The detection method and motor control method of the second zero-crossing point are similar to those of the first zero-crossing point, and the only difference is the detection time and trigger source.

[0043] After detecting the first zero crossing, if Figure 6 The first trigger source of the ADC shown triggers the ADC module to sample the bus voltage and the floating phase terminal voltage, that is, Figure 6 After the first trigger, there is a remaining time in the cycle, namely the first remaining time, and the first remaining time is greater than or equal to the sampling time of the ADC module, which is sufficient for another sampling. The ADC second trigger source is used to implement software-triggered ADC sampling to detect whether there is a second zero crossing point, namely the second trigger in the figure. The third voltage value is detected once each time the software is triggered, and whether there is a second zero crossing point is detected based on the first voltage value and the third voltage value sampled this time. After sampling, the second remaining time of the valid signal is updated. If the remaining time is still greater than or equal to the sampling time of the ADC module, that is, sampling can be performed again, repeated sampling is performed, that is, the ADC second trigger source is used again. Figure 6 The figure shows one hardware trigger and two software triggers in each PWM control cycle. When the remaining time of the valid signal is longer, there can also be three or four software triggered samplings. In this way, when a zero crossing event occurs in any sampling of any cycle, including the detection of the first zero crossing point or the second zero crossing point, the commutation operation can be performed.

[0044] In each cycle, if the second remaining time is insufficient, the ADC first trigger source of the next PWM cycle is started.

[0045] The first remaining time and the second remaining time both refer to the time between the moment after the current sampling ends and the moment when the valid signal ends.

[0046] In one embodiment, the ADC first trigger source includes at least one of the following: a timer, and an event output module.

[0047] The ADC second trigger source is configured to have the following trigger condition: triggering when a preset controller program runs to a program target position.

[0048] The software trigger source relies on code execution to enable the ADC module to start working. The specific target location can be set to any location in the controller program. The hardware trigger source relies on some output signals of the module, such as the update of the timer, the comparison event signal output by the event output module, etc. The method and time of hardware triggering are relatively fixed, and the time of software triggering is relatively free, so that the number of sampling times can be increased more flexibly according to the length of the remaining time.

[0049] From the above, the bus voltage is selected as the reference level and the basis for judging the back electromotive force zero crossing. The ADC module only needs to sample the bus voltage and the voltage of the suspended phase terminal to judge the back electromotive force zero crossing. In addition, since the PWM control cycle in the motor control system is relatively short, usually 50us to 100us. The bus voltage fluctuates little in this process, and the first bus voltage value within a PWM control cycle can be regarded as a fixed value.

[0050] In this way, according to the solution provided by the embodiment of the present invention, only the bus voltage and the floating phase terminal voltage need to be collected in each PWM control cycle, and the obtained voltage value can be used for zero-crossing detection. There is no need to collect all the three-phase terminal voltages. Only two data need to be collected at most for each detection, and the first voltage value of the bus voltage only needs to be collected once, which reduces the number of sampling channels of the required ADC module and shortens the time consumed by sampling. The zero-crossing point can be detected more quickly, thereby improving the efficiency of subsequent motor control and the commutation detection accuracy of the inductive square wave algorithm.

[0051] Furthermore, by using the first ADC trigger source and the second ADC trigger source in combination, it is possible to try to detect the zero-crossing point as many times as possible within a PWM control cycle when the sampling time of the ADC allows, and the detection accuracy can also be improved.

[0052] In one embodiment, the ADC module is configured with a multi-channel integrated trigger mechanism, which includes at least two trigger sources, including an ADC first trigger source and an ADC second trigger source. The first trigger source is an update event trigger source of the PWM timing module; the second trigger source is a software trigger source.

[0053] The update event may be updated once in each PWM cycle, so that an ADC sampling triggered by a hardware trigger source is performed at the beginning of each cycle.

[0054] like Figure 7 As shown, the multi-channel integrated trigger mechanism establishes a trigger mapping relationship between multiple sampling channels and multiple trigger sources.

[0055] ADC channels 1 to 3 are the three sampling channels of the ADC module, and ADC trigger sources 1 to 3 are three independent trigger sources.

[0056] In the multi-channel integrated trigger mechanism, any trigger source is configured to enable one or more sampling channels of the ADC module. Specifically, in the multi-channel integrated trigger mechanism, the ADC module may have an independent trigger mechanism or an integrated trigger mechanism.

[0057] The independent trigger mechanism means that after each trigger source is enabled, the corresponding ADC channel is triggered independently. For example, after trigger source 1 is enabled, ADC channel 1 performs sampling conversion; after trigger source 2 is enabled, ADC channel 2 performs sampling conversion; after trigger source 3 is enabled, ADC channel 3 performs sampling conversion.

[0058] The integrated trigger mechanism means: the difference from the independent trigger mechanism is that after enabling ADC trigger source 1, the ADC module automatically converts the predetermined number of ADC channels in sequence. For example: the predetermined number of ADC channels N is 3, after enabling ADC trigger source 1, the ADC module automatically converts ADC channel 1, ADC channel 2, and ADC channel 3 in sequence. The working mode of other ADC trigger sources is no different from the independent trigger mechanism: after enabling ADC trigger source 2, ADC channel 2 performs sampling conversion; after enabling ADC trigger source 3, ADC channel 3 performs sampling conversion.

[0059] Any ADC trigger source can be set as a hardware trigger source or a software trigger source. For example, ADC trigger source 1 can be set as a hardware trigger source and ADC trigger source 2 can be set as a software trigger source; or both ADC trigger sources 1 and 2 can be set as software trigger sources.

[0060] In this case, the analog-to-digital converter ADC module is triggered to sample the bus voltage and the floating phase terminal voltage of the motor to be sampled, including: When the ADC first trigger source is configured to enable multiple target sampling channels, the ADC module is triggered to sample the target sampling channels in sequence, and the target sampling channels include sampling channels corresponding to the bus voltage and the floating phase terminal voltage.

[0061] For example, using ADC trigger source 1 as the hardware trigger source, the target sampling channels include: ADC channel 1, sampling the bus voltage; ADC channel 2, sampling the floating phase terminal voltage, so that a single triggering behavior of the trigger source can obtain the first voltage value and the second voltage value.

[0062] The software trigger source can be set to ADC trigger source 2 to trigger ADC channel 2 to sample the floating phase terminal voltage. If the remaining time in the current cycle is insufficient, the process ends and the hardware automatically enables trigger source 1 when the next PWM cycle starts.

[0063] Compared with the existing non-sensing square wave technology, in the PWM control cycle, after the ADC module is triggered by hardware for the first time, the trigger mode of the ADC module needs to be modified and then the ADC module needs to be re-triggered. According to the above comprehensive trigger mechanism, the mapping relationship between multiple trigger sources and sampling channels is configured, which can simply and conveniently realize multiple sampling of BLDC back electromotive force in a single PWM control cycle.

[0064] In one embodiment of the present invention, a back electromotive force zero-crossing sampling system is also provided, the system comprising: a three-phase half-bridge drive circuit, a microcontroller unit MCU (Microcontroller Unit); The MCU is used to store a computer program, wherein the computer program is configured to execute the back electromotive force sampling mechanism of the non-inductive square wave control described in any of the above embodiments to determine the zero-crossing point of the back electromotive force; The three-phase half-bridge driving circuit is used to control the commutation operation of the motor to be sampled based on the determined zero-crossing point.

[0065] The zero-crossing point may be the first zero-crossing point or the second zero-crossing point detected.

[0066] like Figure 8 As shown, in the inductive square wave control system of the present invention, the MCU provides six PWM signals to the three-phase half-bridge drive circuit, and drives the BLDC through the three-phase half-bridge drive circuit to realize the voltage control of the BLDC. At the same time, the ADC trigger source of the MCU is set to realize the sampling of the bus voltage and the suspended phase voltage of the BLDC. Among them, the first trigger source of the ADC can realize the sampling of the bus voltage and the suspended phase voltage, and the second trigger source of the ADC only samples the suspended phase voltage. Figure 8 The power supply in is used to power the MCU and the three-phase half-bridge driver.

[0067] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0068] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0069] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0070] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0071] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0073] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A back electromotive force sampling mechanism for non-inductive square wave control, characterized in that: The sampling mechanism includes: In each PWM control cycle of the motor to be sampled, the analog-to-digital converter ADC module is triggered for the first time by the ADC first trigger source to sample the bus voltage and the suspended phase terminal voltage of the motor to be sampled, so as to obtain a first voltage value of the bus voltage and a second voltage value of the suspended phase terminal voltage; Detecting a first zero-crossing point of a back electromotive force based on the first voltage value and the second voltage value, and determining a first remaining time of a valid signal within the PWM control period; If the first remaining time is greater than or equal to the sampling time of the ADC module, the ADC module is triggered by the ADC second trigger source to repeatedly sample the floating phase terminal voltage at least once to obtain a third voltage value of the floating phase terminal voltage, and the second zero crossing point of the back electromotive force is detected according to the first voltage value, the third voltage value and the third voltage value, until the second remaining time of the valid signal after repeated sampling is less than the sampling time of the ADC module.

2. The back electromotive force sampling mechanism of the non-inductive square wave control according to claim 1 is characterized in that: The ADC module is configured with a multi-channel integrated trigger mechanism, which includes at least two trigger sources, including the ADC first trigger source and the ADC second trigger source. The first trigger source is an update event trigger source of the PWM timing module; the second trigger source is a software trigger source.

3. The back electromotive force sampling mechanism of the non-inductive square wave control according to claim 2 is characterized in that: In the multi-channel integrated trigger mechanism, any trigger source is configured to enable one or more sampling channels of the ADC module.

4. The back electromotive force sampling mechanism of the non-inductive square wave control according to claim 3 is characterized in that: The triggering analog-to-digital converter ADC module samples the bus voltage and the suspended phase terminal voltage of the motor to be sampled, including: When the ADC first trigger source is configured to enable multiple target sampling channels, the ADC module is triggered to sample the target sampling channels in sequence, and the target sampling channels include sampling channels corresponding to the bus voltage and the floating phase terminal voltage.

5. The back electromotive force sampling mechanism of the non-inductive square wave control according to claim 1 is characterized in that: The ADC first trigger source includes at least one of the following: Timer and event output module.

6. The back electromotive force sampling mechanism of the non-inductive square wave control according to claim 1 is characterized in that: The ADC second trigger source is configured to have the following trigger conditions: Triggered when the preset controller program runs to the program target position.

7. The back electromotive force sampling mechanism of the non-inductive square wave control according to claim 1 is characterized in that: The detecting a first zero-crossing point of a back electromotive force based on the first voltage value and the second voltage value comprises: If the second voltage value is half of the first voltage value, the time point at which the second voltage value is collected is the first zero-crossing point.

8. A non-inductive square wave controlled back electromotive force sampling control system, characterized in that: The control system comprises: a three-phase half-bridge drive circuit and a micro control unit MCU; The MCU is used to store a computer program, wherein the computer program is configured to execute the back electromotive force sampling mechanism of the inductive square wave control according to any one of claims 1 to 7 to determine the zero-crossing point of the back electromotive force; The three-phase half-bridge driving circuit is used to control the commutation operation of the motor to be sampled based on the determined zero-crossing point.

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