CN215678545U - Non-isolated motor phase current sampling device and motor driving system - Google Patents
Non-isolated motor phase current sampling device and motor driving system Download PDFInfo
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- CN215678545U CN215678545U CN202121616522.6U CN202121616522U CN215678545U CN 215678545 U CN215678545 U CN 215678545U CN 202121616522 U CN202121616522 U CN 202121616522U CN 215678545 U CN215678545 U CN 215678545U
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Abstract
The utility model provides a non-isolated motor phase current sampling device includes: the first end of the sampling resistor is connected to a connection point of an upper bridge arm switching tube and a lower bridge arm switching tube of a one-phase full bridge circuit of the three-phase inverter circuit so as to sample the current of the phase; the positive input end and the negative input end of the isolation operational amplifier are respectively connected with the second end and the first end of the sampling resistor, so that an output signal is generated based on the voltage at the two ends of the sampling resistor; and the bootstrap circuit receives the system voltage and comprises a bootstrap capacitor, the primary side of the isolation operational amplifier is powered by the bootstrap voltage between the positive voltage end and the negative voltage end of the bootstrap capacitor, and the negative voltage end is connected with the connection point of the upper bridge arm switch tube and the lower bridge arm switch tube. The present disclosure also provides a motor drive system.
Description
Technical Field
The disclosure provides a non-isolated motor phase current sampling device and a motor driving system.
Background
In the application of the current high-voltage (more than 48V) driving motor, the methods for detecting the phase current include Hall element detection and resistance detection.
The Hall element detection belongs to non-contact detection, has higher cost and limited precision, and is mainly used for occasions for detecting large current. The high-voltage side of the phase current of the motor is detected by adopting a Hall element, the Hall element is connected in series in a three-phase inverter output circuit, a current signal is converted into a voltage signal, the voltage signal output by the Hall element is conditioned by an operational amplifier, and the conditioned sampling signal is accessed into an ADC unit in an MCU (micro control unit) to control the current of the motor. Because the power supply of the Hall element is opposite to the power ground, the common operational amplifier can be realized, but the technical scheme is suitable for large current detection, and the sampling precision of the current is limited.
The resistance detection is realized through direct electrical connection, the cost is low, the sampling precision is high, and the method is mainly used in the field of precise servo control. Resistance detection is often divided into two ways.
One way is to connect a sampling resistor in series in a lower bridge arm of a three-phase inverter circuit, which belongs to low-voltage side sampling and is easily influenced by the interference of a ground level, and when current loop control is applied, the sampling way limits the output amplitude of three-phase voltage, and the overmodulation of the three-phase voltage becomes especially difficult.
The other mode is to connect a sampling resistor in series in an output loop of a three-phase inverter circuit, belongs to high-voltage side sampling, can accurately detect the phase current of the motor, and can meet the requirement of full voltage output in a current loop by using an overmodulation technology. At present, a Hall element is mostly adopted for sampling the high-voltage side of the phase current of a motor, the precision is low, and the application in precision servo control is not facilitated; the sampling resistor detects that high-voltage side phase current mostly uses an isolation power supply to drive a bridge arm power switch on a three-phase inverter circuit, so that the cost is high and the size is large. Under the condition of adopting a resistance detection mode, the high-voltage side of the motor phase current adopts an isolated sampling resistor for detection, the sampling resistor is connected in series in a three-phase inverter output circuit, voltage signals at two ends of the sampling resistor are connected into an isolated differential operational amplifier for signal conditioning, and the conditioned sampling signal is connected into an ADC unit in an MCU (micro control unit) for motor current control. The motor drive adopts the pulse modulation technology, and the voltage at two ends of the sampling resistor contains the common-mode voltage of 0V and bus voltage which are alternately changed, so that an additional isolation power supply is needed to supply power to the isolation operational amplifier input side and the bridge arm power switch driving circuit on the three-phase inverter circuit, the size is increased, and the cost is high.
SUMMERY OF THE UTILITY MODEL
In order to solve one of the above technical problems, the present disclosure provides a non-isolated motor phase current sampling device and a motor driving system.
According to the method, an isolation power supply is not needed, the bootstrap capacitor supplies power for the isolation operational amplifier, the sampling of the phase current high-voltage side of the motor is achieved, the full-range voltage overmodulation output can be simply achieved in a strategy of using the current closed-loop control motor, in addition, according to the scheme provided by the method, the sampling of the phase current can be achieved by collecting two-phase current, and the three-phase current is collected completely without changing.
According to one aspect of the present disclosure, a non-isolated motor phase current sampling apparatus includes:
the first end of the sampling resistor is connected to a connection point of an upper bridge arm switching tube and a lower bridge arm switching tube of a one-phase full bridge circuit of the three-phase inverter circuit so as to sample the current of the phase;
the positive input end and the negative input end of the isolation operational amplifier are respectively connected with the second end and the first end of the sampling resistor, so that an output signal is generated based on the voltage at the two ends of the sampling resistor; and
the bootstrap circuit receives system voltage and comprises a bootstrap capacitor, the primary side of the isolation operational amplifier is powered by bootstrap voltage between a positive voltage end and a negative voltage end of the bootstrap capacitor, and the negative voltage end is connected with a connection point of the upper bridge arm switch tube and the lower bridge arm switch tube.
According to at least one embodiment of the present disclosure, the apparatus further includes a first voltage conversion circuit, where the first voltage conversion circuit converts a bootstrap voltage at two ends of the bootstrap capacitor into a first voltage, and the first voltage is used as a primary supply voltage of the isolation operational amplifier.
According to at least one embodiment of the present disclosure, the power supply further comprises a second voltage conversion circuit, wherein the second voltage conversion circuit converts a system voltage into a second voltage, and the second voltage is used as a secondary side power supply voltage of the isolation operational amplifier.
According to at least one embodiment of the present disclosure, further comprising:
a filter circuit that low-pass filters an output signal of the isolation operational amplifier and generates a filtered signal;
a differential operational amplifier receiving the filtered signal and powered by the second voltage; and
and the analog-to-digital converter receives the output signal of the differential operational amplifier so as to perform analog-to-digital conversion, thereby acquiring a sampling current value.
According to at least one embodiment of the present disclosure, the bootstrap circuit further includes a bootstrap diode, an anode of the bootstrap diode is connected to a system voltage, and a cathode of the bootstrap diode is connected to a positive voltage terminal of the bootstrap capacitor, so as to generate the bootstrap voltage across the bootstrap capacitor.
According to at least one embodiment of the present disclosure, the upper bridge arm switching tube and the lower bridge arm switching tube are one of a MOSFET, an IGBT, a GaN switch, and a SCI-MOSFET, and the bootstrap voltage of the bootstrap capacitor provides a gate-source voltage of the upper bridge arm switching tube.
According to at least one embodiment of the present disclosure, the first terminal of the sampling resistor and the negative voltage terminal of the bootstrap capacitor are kept at the same potential, and the primary ground of the isolation operational amplifier and the negative input terminal of the isolation operational amplifier are kept at the same potential.
According to another aspect of the present disclosure, a motor drive system includes:
the phase current sampling apparatus as set forth in any one of the above; and
at least two full-bridge circuits of three-phase full-bridge circuits of the three-phase inverter circuit are respectively connected with the sampling devices so as to obtain the phase current of the motor through the respectively connected sampling devices,
and the first end of the sampling resistor corresponding to the full-bridge circuit is connected with the corresponding phase winding of the three-phase motor.
According to at least one embodiment of the present disclosure, the bridge arm switching device further comprises a driving circuit, wherein the driving circuit receives a control signal for controlling the upper bridge arm switching tube and the lower bridge arm switching tube, and provides the control signal to the upper bridge arm switching tube and the lower bridge arm switching tube so as to control the upper bridge arm switching tube and the lower bridge arm switching tube to be connected and disconnected.
According to at least one embodiment of the present disclosure, the upper bridge arm switching tube and the lower bridge arm switching tube are MOSFETs, a drain of the upper bridge arm switching tube is connected to a bus voltage for supplying power to the motor, a source of the lower bridge arm switching tube is grounded, a source of the upper bridge arm switching tube is connected to a drain of the lower bridge arm switching tube as the connection point, and gates of the upper bridge arm switching tube and the lower bridge arm switching tube are connected to the control signal.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.
Fig. 1 shows a schematic view of a motor drive system according to one embodiment of the present disclosure.
Fig. 2 shows a schematic diagram of a motor drive system according to an embodiment of the present disclosure.
Fig. 3 shows a circuit diagram of a non-isolated motor phase current sampling apparatus according to one embodiment of the present disclosure.
FIG. 4 illustrates a flow chart of a non-isolated motor phase current sampling method according to one embodiment of the present disclosure.
Detailed Description
The present disclosure will be described in further detail with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limitations of the present disclosure. It should be further noted that, for the convenience of description, only the portions relevant to the present disclosure are shown in the drawings.
It should be noted that the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict. Technical solutions of the present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Unless otherwise indicated, the illustrated exemplary embodiments/examples are to be understood as providing exemplary features of various details of some ways in which the technical concepts of the present disclosure may be practiced. Accordingly, unless otherwise indicated, features of the various embodiments may be additionally combined, separated, interchanged, and/or rearranged without departing from the technical concept of the present disclosure.
The use of cross-hatching and/or shading in the drawings is generally used to clarify the boundaries between adjacent components. As such, unless otherwise noted, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for a particular material, material property, size, proportion, commonality between the illustrated components and/or any other characteristic, attribute, property, etc., of a component. Further, in the drawings, the size and relative sizes of components may be exaggerated for clarity and/or descriptive purposes. While example embodiments may be practiced differently, the specific process sequence may be performed in a different order than that described. For example, two processes described consecutively may be performed substantially simultaneously or in reverse order to that described. In addition, like reference numerals denote like parts.
When an element is referred to as being "on" or "on," "connected to" or "coupled to" another element, it can be directly on, connected or coupled to the other element or intervening elements may be present. However, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element, there are no intervening elements present. For purposes of this disclosure, the term "connected" may refer to physically, electrically, etc., and may or may not have intermediate components.
For descriptive purposes, the present disclosure may use spatially relative terms such as "below … …," below … …, "" below … …, "" below, "" above … …, "" above, "" … …, "" higher, "and" side (e.g., as in "side wall") to describe one component's relationship to another (other) component as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use, operation, and/or manufacture in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below … …" can encompass both an orientation of "above" and "below". Further, the devices may be otherwise positioned (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, when the terms "comprises" and/or "comprising" and variations thereof are used in this specification, the presence of stated features, integers, steps, operations, elements, components and/or groups thereof are stated but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. It is also noted that, as used herein, the terms "substantially," "about," and other similar terms are used as approximate terms and not as degree terms, and as such, are used to interpret inherent deviations in measured values, calculated values, and/or provided values that would be recognized by one of ordinary skill in the art.
According to one embodiment of the present disclosure, a non-isolated motor phase current sampling device is provided.
Fig. 1 illustrates a motor drive system including a non-isolated motor phase current sampling apparatus according to one embodiment of the present disclosure in accordance with one embodiment of the present disclosure.
The non-isolated motor phase current sampling device can comprise a sampling resistor, an isolation operational amplifier and a bootstrap circuit.
The first end of the sampling resistor is connected to a connection point of an upper bridge arm switching tube and a lower bridge arm switching tube of a one-phase full bridge circuit of the three-phase inverter circuit so as to sample the current of the phase. The second end of the sampling resistor may be connected to a winding of a corresponding phase of the motor.
In the present disclosure, the three-phase inverter circuit may be in the form of a three-phase full-bridge circuit, and may include an upper bridge arm switching tube and a lower bridge arm switching tube for each phase of the full-bridge circuit, where the upper bridge arm switching tube and the lower bridge arm switching tube may be one of a MOSFET (metal-oxide semiconductor field effect transistor), an IGBT, a GaN (gallium nitride) switch, an SCI-MOSFET (silicon carbide field effect transistor), and the like. The MOSFET will be described as an example.
For the three-phase full-bridge circuit, the grid electrode of the MOSFET of the upper bridge arm can be connected with a first PWM control signal, and the grid electrode of the MOSFET of the lower bridge arm can be connected with a second PWM control signal, so that the MOSFET of the upper bridge arm and the MOSFET of the lower bridge arm can be controlled to be switched on and off respectively through the first PWM control signal and the second PWM control signal. In addition, the sampling resistor can be connected to a connection point of the MOSFETs of the upper arm and the MOSFETs of the lower arm of any two phases in the three-phase full bridge circuit, and further connected to the corresponding motor phase winding.
The drain of the MOSFET of the upper arm may be connected to a bus voltage, the drain of the MOSFET of the lower arm may be connected to the source of the MOSFET of the upper arm as the connection point, and the source of the MOSFET of the lower arm may be grounded.
The first PWM control signal and the second PWM control signal may be provided by a driving circuit as described in fig. 1.
The isolation operational amplifier is used for amplifying the collected signals of the sampling resistor. The isolation operational amplifier comprises a primary side and a secondary side, wherein a positive input end and a negative input end of the isolation operational amplifier are positioned on the primary side, and an output end of the isolation operational amplifier is positioned on the secondary side.
The positive input end and the negative input end of the isolation operational amplifier are respectively connected with the second end and the first end of the sampling resistor, so that an output signal is generated based on the voltage at the two ends of the sampling resistor. The first end of the sampling resistor is connected with the corresponding phase winding of the three-phase motor.
And the bootstrap circuit receives the system voltage and comprises a bootstrap capacitor, the primary side of the isolation operational amplifier is powered by the bootstrap voltage between the positive voltage end and the negative voltage end of the bootstrap capacitor, and the negative voltage end is connected with the connection point of the upper bridge arm switch tube and the lower bridge arm switch tube.
The bootstrap circuit further includes a bootstrap diode, an anode of the bootstrap diode is connected to the system voltage, and a cathode of the bootstrap diode is connected to a positive voltage terminal of the bootstrap capacitor, so as to generate a bootstrap voltage across the bootstrap capacitor.
A bootstrap voltage (boost voltage) may be provided by the bootstrap circuit, which may be substantially equal to the sum of the system voltage and the capacitor voltage after charging of the capacitor.
An isolated operational amplifier according to the present disclosure includes a primary side supply terminal and a secondary side supply terminal. Correspondingly, the non-isolated motor phase current sampling device further comprises a first voltage conversion circuit, the first voltage conversion circuit converts the bootstrap voltage at two ends of the bootstrap capacitor into a first voltage, and the first voltage is used as a primary power supply voltage of the isolation operational amplifier.
In the first conversion circuit, a voltage input end of the first voltage conversion circuit is connected with a positive voltage end of the bootstrap capacitor, and a grounding end of the first voltage conversion circuit is connected with a negative voltage end of the bootstrap capacitor. And a first decoupling capacitor can be connected between the voltage input end of the first voltage conversion circuit and the grounding end, and a second decoupling capacitor can be connected between the output end of the first voltage conversion circuit and the grounding end, so that the interference of noise is eliminated. For example, in the present disclosure, the system voltage may be 15V and the primary supply voltage of the isolation operational amplifier may be 5V.
In addition, the primary ground of the isolation operational amplifier can be connected with the negative voltage end of the bootstrap capacitor. Through the technical scheme of the disclosure, the first end of the sampling resistor and the negative voltage end of the bootstrap capacitor are kept at the same potential, and the primary side ground of the isolation operational amplifier and the negative input end of the isolation operational amplifier are kept at the same potential. Therefore, the detection effect of the primary side signal of the isolation operational amplifier can be better. Furthermore, a separate isolation power supply for the isolation operational amplifier is also required. The bootstrap capacitor is used for supplying power to the isolation operational amplifier, so that high-voltage side sampling of the phase current of the motor can be realized, and full-range voltage overmodulation output can be simply realized in a strategy of using a current closed-loop control motor.
In the prior art, a sampling resistor is connected to a source terminal (ground terminal) of a lower bridge arm MOSFET, and this connection mode belongs to low-voltage side sampling and is easily affected by ground level interference, and in this case, each phase current of three-phase current needs to be collected. And when the current loop control is applied, the sampling mode limits the output amplitude of the three-phase voltage, and the overmodulation of the three-phase voltage is particularly difficult to realize. Therefore, the technical scheme disclosed by the invention can well solve the problems in the prior art. In the method, the acquisition of any two-phase current of three-phase current can be realized, namely the acquisition of the phase current of the motor can be realized, so that the motor control is realized, and in the application of precise servo control, an additional isolation power supply is not required to be provided, so that the hardware cost and the volume for constructing the isolation power supply are saved.
According to a further embodiment of the present disclosure, the non-isolated motor phase current sampling apparatus may further include a second voltage conversion circuit that converts the system voltage into a second voltage, the second voltage being a secondary supply voltage of the isolated operational amplifier.
Further, a motor drive system according to an embodiment of the present disclosure is shown in fig. 2, wherein a non-isolated motor phase current sampling apparatus according to an embodiment of the present disclosure is included in the motor drive system.
Compared with fig. 1, the non-isolated motor phase current sampling apparatus of fig. 2 may further include: the circuit comprises a filter circuit, a differential operational amplifier and an analog-to-digital converter. The filter circuit low-pass filters an output signal of the isolation operational amplifier and generates a filtered signal. A differential operational amplifier receiving the filtered signal and powered by the second voltage. And the analog-to-digital converter receives the output signal of the differential operational amplifier so as to perform analog-to-digital conversion, thereby acquiring a sampled current value.
As described above, when the upper arm switch tube and the lower arm switch tube are MOSFETs, the bootstrap voltage of the bootstrap capacitor provides the gate-source voltage of the upper arm switch tube.
Fig. 3 shows a circuit diagram of a non-isolated motor phase current sampling apparatus according to one embodiment of the present disclosure. In fig. 3, a current sampling apparatus of a one-phase full bridge circuit of a three-phase inverter circuit is shown.
As shown in FIG. 3, drive circuit U1 may receive control signals, such as PWM control signals PWM1A and PWM1B, PWM control signal PWM1A for controlling upper arm MOSFET-Q1 and PWM control signal PWM1B for controlling lower arm MOSFET-Q2.
In this disclosure, driver circuit U1 may select full bridge driver chip IR2183S, where pin HIN of the chip receives PWM control signal PWM1A and pin LIN receives PWM control signal PWM 1B. The resistors R1, R2 may be series matched resistors for the PWM control signal.
Pin VCC of the chip may receive a system voltage VCC, for example, the VCC may be 15V or the like.
The anode of the bootstrap diode D1 is connected to the system voltage VCC, the cathode is connected to the positive voltage terminal of the bootstrap capacitor C1, and the connection point of the bootstrap diode D1 and the bootstrap capacitor C1 may be connected to the VB pin of the chip.
Resistors R3 and R4 are the gate resistor of the upper arm MOSFET-Q1 and the gate resistor of the lower arm MOSFET-Q2, respectively. And resistors R3, R4 are connected to the HO pin and LO pin of the chip, respectively.
The pin VS is connected with the connection point of the upper bridge arm MOSFET-Q1 and the lower bridge arm MOSFET-Q2, the negative voltage end of the bootstrap capacitor C1 is connected with the pin LO, and the voltage of the connection point is used as the voltage V0 of the negative voltage end of the bootstrap capacitor.
The upper arm MOSFET-Q1 and the lower arm MOSFET-Q2 are connected in series, and the drain of the upper arm MOSFET-Q1 is connected to a bus voltage Ubus that provides voltage to the phase windings of the motor.
Thus, the control signals control the upper arm MOSFET-Q1 and the lower arm MOSFET-Q2 to be switched on or off, so that the bus voltage Ubus is supplied to the phase windings of the three-phase motor.
The resistor R5 is a phase current sampling resistor, and supplies the bus voltage Ubus to the phase windings of the three-phase motor via the resistor R5. In addition, because the sampling resistor can be connected to at least two phases of full bridge circuits in the present disclosure, in the case that phase current collection can be realized only by connecting two phases using resistors, one phase without connecting the sampling resistor can directly supply the bus voltage Ubus to the corresponding phase winding.
The resistor R5 may be connected across two inputs IN + of the isolation operational amplifier U4 and ON-connected to the voltages VS + and VS-across the resistor R5 to collect and amplify the voltage across the resistor R5. The isolation operational amplifier U4 may be selected as chip HCPL 7840.
The chips U2 and U3 are 15V to 5V voltage conversion circuits, which may be, for example, the ldo 78L 05.
The voltage input terminal IN of the chip U2 may be connected to the voltage V1 of the positive voltage terminal of the bootstrap capacitor C1, and the output terminal of the chip U2 may be connected to the primary supply voltage pin VDD1 of the isolation operational amplifier U4. The capacitors C2 and C3 are input decoupling capacitors and output decoupling capacitors of the voltage regulator 78L05, respectively. One end of the capacitor C2 may be connected to the voltage input terminal IN of the chip U2, the other end may be connected to the ground terminal COM of the chip U2, and the ground terminal COM of the chip U2 is connected to the voltage V0 of the negative voltage terminal of the bootstrap capacitor. The capacitor C3 may have one end connected to the voltage output terminal OUT of the chip U2 and the other end connected to the ground terminal COM of the chip U2.
In addition, the primary ground GND1 of the isolation operational amplifier U4 should be connected to the voltage V0 of the negative terminal of the bootstrap capacitor.
The secondary supply voltage pin VDD2 of the isolation operational amplifier U4 is connected with the voltage converted and output by the voltage conversion chip U3. The chip U3 may be a LDO 78L 05. Capacitors C4 and C5 are input and output decoupling capacitors, respectively, of regulator 78L 05.
The capacitor C4 has one end connected to the voltage input IN of the chip U3 and the other end connected to the ground terminal COM of the chip U3. The voltage input IN may be connected to a system voltage, for example, a voltage of 15V, and the ground terminal COM of the chip U3 is grounded. The capacitor C5 may have one end connected to the voltage output terminal OUT of the chip U3 and the other end connected to the ground terminal COM of the chip U3.
In addition, the secondary ground GND2 of the isolation operational amplifier U4 should be grounded.
According to a further embodiment of the present disclosure, a differential operational amplifier U5 may also be included, wherein the positive input of the differential operational amplifier U5 is connected to the positive input OUT + of the isolation operational amplifier U4 through a resistor R6, and the negative input of the differential operational amplifier U5 is connected to the negative input OUT-of the isolation operational amplifier U4 through a resistor R7. The resistors R6 and R7 are conditioning resistors of the differential operational amplifier U5. Besides, conditioning resistors R8 and R9 may be further provided, one end of R8 may be connected to a reference voltage VREF, the other end of R8 may be connected to the positive input terminal of the differential operational amplifier U5, one end of R9 may be connected to the output terminal of the differential operational amplifier U5, and the other end of R9 may be connected to the negative input terminal of the differential operational amplifier U5. In the present disclosure, it may be provided that: r6 ═ R7, R8 ═ R9.
Furthermore, filter capacitors C6, C7 may be provided. The capacitors C6 and C7 may be low-pass filter capacitors, and the capacitor C6 may be connected in series across the resistor R8, and the capacitor C7 may be connected in series across the resistor R9, so as to implement the function of low-pass filtering the output signal of the isolation operational amplifier U4.
The differential operational amplifier U5 may be connected to an analog-to-digital converter (ADC) to analog-to-digital convert the output voltage of the differential operational amplifier U5. Resistor R10 may also be set as the ADC sample input series resistor.
In the disclosure, PWM1A and PWM1B are pulse modulation signals from a singlechip, and the voltage amplitude is 0-3.3V. The system voltage VCC may be a 15V signal with respect to the driving circuit supply ground GND. GND is the power ground of the driving circuit. VREF is a reference voltage relative to GND.
Further, in the present disclosure, there is also provided a motor driving system, which may include: the phase current sampling apparatus as described in any of the above; the sampling device is connected respectively to arbitrary two-phase full-bridge circuit or three-phase full-bridge circuit in three-phase inverter circuit's the three-phase full-bridge circuit to obtain corresponding looks sampling current through the sampling device who connects respectively, wherein, the first end of the sampling resistance that corresponding looks full-bridge circuit corresponds is connected with three-phase motor's the corresponding looks winding.
The motor driving system can further comprise a driving circuit, wherein the driving circuit receives control signals for controlling the upper bridge arm switching tube and the lower bridge arm switching tube and provides the control signals to the upper bridge arm switching tube and the lower bridge arm switching tube so as to control the upper bridge arm switching tube and the lower bridge arm switching tube to be connected and disconnected. The upper bridge arm switching tube and the lower bridge arm switching tube are MOSFETs, the drain electrode of the upper bridge arm switching tube is connected with a bus voltage for supplying power to the motor, the source electrode of the lower bridge arm switching tube is grounded, the source electrode of the upper bridge arm switching tube is connected with the drain electrode of the lower bridge arm switching tube to serve as a connection point, and the grid electrodes of the upper bridge arm switching tube and the lower bridge arm switching tube are connected with a control signal.
According to a further embodiment of the present disclosure, a phase current sampling method is also provided. Fig. 4 illustrates a phase current sampling method S100 according to the present disclosure. The method can include the steps of S102, controlling the lower bridge arm switching tube to be conducted and the upper bridge arm switching tube to be disconnected through control signals so as to charge a bootstrap capacitor through system voltage to generate bootstrap voltage, S104, supplying power to a primary side of an isolation operational amplifier based on the bootstrap voltage, and S106, collecting current of a corresponding phase of a motor through a phase current collecting device.
Specifically, PWM1A and PWM1B drive Q1 and Q2 to turn on and off, respectively, when Q2 is turned on, a system voltage VCC charges a bootstrap capacitor C1 through a diode D1 and a MOSFET-Q2, and when Q2 is turned off and Q1 is turned on, a voltage VCC across the bootstrap capacitor C1 provides a gate-source voltage for the turn-on of Q1, which ensures that Q1 can be turned on completely and quickly. Meanwhile, the voltage at the two ends of the bootstrap capacitor C1 is converted into 5V voltage through the voltage stabilizing chip U2 to provide power for the primary side of the isolation operational amplifier U4, and at the moment, the voltage VS-at one end of the sampling resistor R5 is the same as the potential of the negative voltage end V0 of the bootstrap capacitor C1, so that the primary side negative input IN-of the isolation operational amplifier U4 and the primary side ground GND1 keep the same potential, and the primary side signal detection of the isolation operational amplifier U4 can operate more effectively. The voltage difference between the secondary output signals OUT +/OUT-of the isolation operational amplifier is a fixed ratio K of the voltage difference between the primary input signals IN +/IN-, and the secondary output signals OUT +/OUT-are connected with the conditioning output signals U of the differential operational amplifierADCVoltage and phase current IUThe conversion relationship is as follows:
where K is a fixed ratio, R8 is the resistance of resistor R8, R6 is the resistance of resistor R6, and R5 is the resistance of resistor R5.
In addition, R8 and C6, R9 and C7 provide low pass filtering for the input signals of the positive and negative inputs, respectively, of the differential operational amplifier U5 with a filter time constant τ of:
τ＝R8·C6＝R9·C7
wherein C6 is the capacitance of the capacitor C6, and C7 is the capacitance of the capacitor C7.
According to the embodiment of the disclosure, the problem that the low-voltage side current sampling of the lower bridge arm limits the voltage output is solved by sampling the high-voltage side of the phase current of the motor, the hardware cost and the volume for constructing an isolation power supply are saved by adopting the voltage of the bootstrap capacitor to supply power to the primary side of the isolation operational amplifier, and the technical problem of collecting the phase current of the high-voltage side in a non-isolation motor driving circuit is solved.
In the description herein, reference to the description of the terms "one embodiment/mode," "some embodiments/modes," "example," "specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment/mode or example is included in at least one embodiment/mode or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to be the same embodiment/mode or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments/modes or examples. Furthermore, the various embodiments/aspects or examples and features of the various embodiments/aspects or examples described in this specification can be combined and combined by one skilled in the art without conflicting therewith.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
It will be understood by those skilled in the art that the foregoing embodiments are merely for clarity of illustration of the disclosure and are not intended to limit the scope of the disclosure. Other variations or modifications may occur to those skilled in the art, based on the foregoing disclosure, and are still within the scope of the present disclosure.
Claims (10)
1. A non-isolated motor phase current sampling device, comprising:
the first end of the sampling resistor is connected to a connection point of an upper bridge arm switching tube and a lower bridge arm switching tube of a one-phase full bridge circuit of the three-phase inverter circuit so as to sample the current of the phase;
the positive input end and the negative input end of the isolation operational amplifier are respectively connected with the second end and the first end of the sampling resistor, so that an output signal is generated based on the voltage at the two ends of the sampling resistor; and
the bootstrap circuit receives system voltage and comprises a bootstrap capacitor, the primary side of the isolation operational amplifier is powered by bootstrap voltage between a positive voltage end and a negative voltage end of the bootstrap capacitor, and the negative voltage end is connected with a connection point of the upper bridge arm switch tube and the lower bridge arm switch tube.
2. The phase current sampling apparatus of claim 1, further comprising a first voltage conversion circuit, wherein the first voltage conversion circuit converts a bootstrap voltage across the bootstrap capacitor into a first voltage, and the first voltage is used as a primary supply voltage of the isolation operational amplifier.
3. The phase current sampling apparatus of claim 2, further comprising a second voltage conversion circuit that converts a system voltage to a second voltage as a secondary supply voltage for the isolated operational amplifier.
4. The phase current sampling apparatus of claim 3, further comprising:
a filter circuit that low-pass filters an output signal of the isolation operational amplifier and generates a filtered signal;
a differential operational amplifier receiving the filtered signal and powered by the second voltage; and
and the analog-to-digital converter receives the output signal of the differential operational amplifier so as to perform analog-to-digital conversion, thereby acquiring a sampling current value.
5. The phase current sampling apparatus of claim 1, wherein the bootstrap circuit further comprises a bootstrap diode, an anode of the bootstrap diode is connected with a system voltage, and a cathode of the bootstrap diode is connected with a positive voltage terminal of the bootstrap capacitor, so as to generate the bootstrap voltage across the bootstrap capacitor.
6. The phase current sampling device of claim 1, wherein the upper bridge arm switching tubes and the lower bridge arm switching tubes are MOSFETs, and the bootstrap voltage of the bootstrap capacitor provides the gate-source voltage of the upper bridge arm switching tubes.
7. The sampling device of claim 1, wherein the first terminal of the sampling resistor is at the same potential as the negative terminal of the bootstrap capacitor, and the primary ground of the isolation operational amplifier is at the same potential as the negative input terminal of the isolation operational amplifier.
8. A motor drive system, comprising:
phase current sampling apparatus according to any one of claims 1 to 7;
at least two full-bridge circuits of three-phase full-bridge circuits of the three-phase inverter circuit are respectively connected with the sampling devices so as to obtain the phase current of the motor through the respectively connected sampling devices,
and the first end of the sampling resistor corresponding to the full-bridge circuit is connected with the corresponding phase winding of the three-phase motor.
9. The motor drive system according to claim 8, further comprising a drive circuit that receives control signals for controlling the upper arm switching tubes and the lower arm switching tubes and supplies the control signals to the upper arm switching tubes and the lower arm switching tubes so as to control the upper arm switching tubes and the lower arm switching tubes to be turned on and off.
10. The motor driving system according to claim 9, wherein the upper arm switch tube and the lower arm switch tube are MOSFETs, and drain electrodes of the upper arm switch tube and the lower arm switch tube are connected to a bus voltage for supplying power to the motor, a source electrode of the lower arm switch tube is grounded, a source electrode of the upper arm switch tube is connected to a drain electrode of the lower arm switch tube as the connection point, and gates of the upper arm switch tube and the lower arm switch tube are connected to the control signal.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114879797A (en) * | 2022-06-30 | 2022-08-09 | 南京宏泰半导体科技有限公司 | High-voltage current source control system and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114879797A (en) * | 2022-06-30 | 2022-08-09 | 南京宏泰半导体科技有限公司 | High-voltage current source control system and method |
| CN114879797B (en) * | 2022-06-30 | 2022-09-06 | 南京宏泰半导体科技有限公司 | High-voltage current source control system and method |
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