Bias voltage detection circuit and motor control system

Abstract

The utility model relates to the technical field of power electronics, and discloses a bias voltage detection circuit and a motor control system. According to the device, the forward sampling circuit and the reverse sampling circuit are arranged to collect and detect the bias voltage corresponding to the current output by the current sensor, and then the summing circuit is used for summing the collected and detected forward and reverse voltages to output the bias voltage. And the output bias voltage is not changed, so that the problem of bias voltage excursion caused by excursion of the acquired output current due to the influence of external factors is avoided.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a bias voltage detection circuit and a motor control system. Background Technology

[0002] With the continuous development of power electronics technology, especially motor control technology in automobiles, in order to better control the motor, a current sensor is installed inside the motor controller. The current sensor samples the voltage signal of the motor in real time and performs correction.

[0003] However, in the current implementation scheme, although the current sensor can acquire voltage signals, it is affected by factors such as temperature, power supply, and interference, so the current waveform it samples is not symmetrical. This will cause the output bias voltage to deviate to a certain extent, affecting the final output speed and torque of the motor. Utility Model Content

[0004] In view of this, this application proposes a bias voltage detection circuit and a motor control system to solve the problem that the bias voltage of the sampling output of existing current sensors is prone to deviation due to the influence of external factors.

[0005] The first aspect of this application provides a bias voltage detection circuit, including: a forward sampling circuit, a reverse sampling circuit, and an adder circuit; the forward sampling circuit and the reverse sampling circuit are connected in parallel, and their output terminals are connected to the input terminals of the adder circuit; the output terminals of the adder circuit are connected to a target device, and are used to sum the forward voltage output by the forward sampling circuit and the reverse voltage output by the reverse sampling circuit to obtain a bias voltage.

[0006] In one feasible implementation, the forward sampling circuit includes a first amplifier and a first filter circuit; the forward input terminal of the first amplifier receives the forward voltage signal of the target device, and the first filter circuit is disposed at the inverted input terminal and the output terminal of the first amplifier.

[0007] In one feasible implementation, the reverse sampling circuit includes a second amplifier and a second filter circuit; the positive input terminal of the second amplifier receives the reverse voltage signal of the target device, and the second filter circuit is disposed at the positive input terminal and the output terminal of the second amplifier.

[0008] In one feasible implementation, the bias voltage detection circuit further includes a first current limiting circuit connected to the positive input terminal of the positive sampling circuit and connected to the positive input terminal of the reverse sampling circuit.

[0009] In one feasible implementation, the adder circuit includes a third amplifier and a third filter circuit; the positive input terminal of the third amplifier is connected to the output terminals of the positive sampling circuit and the negative sampling circuit, respectively, and the negative input terminal and the output terminal of the third amplifier are connected to the third filter circuit.

[0010] In one feasible implementation, the third filter circuit includes two third resistors and a capacitor with equal resistance values. One third resistor and the capacitor are connected in parallel and placed between the inverting input terminal and the output terminal of the third amplifier. The other third resistor is connected to the inverting input terminal of the third amplifier and then grounded.

[0011] In one feasible implementation, the adder circuit further includes a voltage divider circuit; the voltage divider circuit is located between the output terminal of the third amplifier and ground, and the output terminal of the voltage divider circuit is connected to the controller.

[0012] In one feasible implementation, the voltage divider circuit includes a first resistor and a second resistor connected in series, wherein the first resistor and the second resistor have equal resistance values, and the common terminal of the first resistor and the second resistor is connected to the controller of the target device.

[0013] In one feasible implementation, the adder circuit further includes two second current-limiting resistors, one of which is located between the output of the forward sampling circuit and the positive input of the third amplifier, and the other is located between the output of the reverse sampling circuit and the positive input of the third amplifier.

[0014] A second aspect of this application provides a motor control system, comprising: a bias voltage detection circuit, a current sensor, a controller, and a motor as described above; the current sensor is disposed on each phase line of the motor for acquiring current signals of the target device and outputting them to the corresponding sampling unit for sampling of forward and reverse voltages; the output terminal of the adder circuit is connected to the analog sampling port of the controller.

[0015] The technical solution provided in this application includes a forward sampling circuit, a reverse sampling circuit, and an adder circuit. The forward and reverse sampling circuits are connected in parallel, and their output terminals are connected to the input terminals of the adder circuit. The output terminal of the adder circuit is connected to the target device and is used to sum the forward voltage output by the forward sampling circuit and the reverse voltage output by the reverse sampling circuit to obtain a bias voltage. This application, by setting up forward and reverse sampling circuits to acquire and detect the bias voltage on the target device, and then using the adder circuit to sum the acquired and detected forward and reverse voltages to output a bias voltage, ensures that the output bias voltage remains constant as long as the amplitude of the current signal remains unchanged. This avoids the problem of bias voltage deviation caused by external factors affecting the output current deviation on the target device. Attached Figure Description

[0016] Figure 1 This is a first schematic diagram of a bias voltage detection circuit provided in an embodiment of this application;

[0017] Figure 2 This is a second schematic diagram of the bias voltage detection circuit provided in the embodiments of this application;

[0018] Figure 3 A circuit schematic diagram of a bias voltage detection circuit provided in an embodiment of this application;

[0019] Figure 4 A schematic diagram of the addition circuit provided in an embodiment of this application;

[0020] Figure 5 This is a schematic diagram of a motor control system provided in an embodiment of this application. Detailed Implementation

[0021] This application provides a bias voltage detection circuit and a motor control system. It mainly uses a device including a forward sampling circuit and a reverse sampling circuit to sample the output current of the target device in both forward and reverse directions. Then, an adder circuit is used to add the sampled currents to output a bias voltage. In this way, the bias voltage can be obtained accurately without considering the influence of the output current of the target device, so as to avoid torque deviation and vehicle stalling when driving the motor, which would affect the driving experience of passengers.

[0022] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] like Figure 1 As shown in the embodiment of this application, a bias voltage detection circuit is provided. The circuit includes a forward sampling circuit 121, a reverse sampling circuit 122, and an adder circuit 123. The forward sampling circuit 121 and the reverse sampling circuit 122 are connected in parallel, and their output terminals are connected to the input terminals of the adder circuit 123.

[0024] The output of the adder circuit 123 is connected to the target device and is used to sum the positive voltage output by the positive sampling circuit 121 and the reverse voltage output by the reverse sampling circuit 122, and output a bias voltage to the controller.

[0025] It should be noted that the forward sampling circuit 121 is input to a forward voltage signal and the reverse sampling circuit 122 is input to a reverse voltage signal. Both the forward and reverse voltage signals can be obtained by converting the current signal on the phase line of the target device acquired by the sensor.

[0026] Specifically, current sensors can be installed on the phase lines of the target device, that is, on the phase lines of the target device to be tested, to collect the current signals of the target device, that is, the current signals of each phase line of the target device.

[0027] One input terminal of the forward sampling circuit 121 and the reverse sampling circuit 122 is connected to the output terminal of the current sensor to sample the voltage corresponding to the current signal output by the current sensor in order to output a bias voltage.

[0028] In practical applications, this current sensor can be an electromagnetic current transformer, an electronic current transformer, or a Hall effect current sensor. The phase line to be tested in the target device is wound around the current sensor, and the current of the phase line to be tested is detected based on the principle of electromagnetic induction. The current sensor has two output terminals: a forward output terminal and a reverse output terminal. The output terminals of the forward sampling circuit 121 and the reverse sampling circuit 122 correspond to the forward and reverse output terminals of the current sensor, respectively. After receiving the forward and reverse current signals from the current sensor, the forward sampling circuit 121 and the reverse sampling circuit 122 acquire and detect the voltage corresponding to the forward and reverse current signals. Specifically, they sample the forward and reverse current values ​​at the same time to determine the corresponding voltage values, and then add the forward and reverse voltage values ​​together to obtain the bias voltage.

[0029] Understandably, the number of forward sampling circuits 121 and reverse sampling circuits 122 in the bias voltage detection circuit is determined according to the number of phases of the target device, such as single-phase lines, two-phase lines, three-phase lines, multi-phase lines, etc. Each phase line can be equipped with a forward sampling circuit 121 and a reverse sampling circuit 122 respectively. The bias voltage of the corresponding phase line is detected by the forward sampling circuit 121 and the reverse sampling circuit 122 for subsequent analysis of whether the voltage in the phase line is abnormal.

[0030] In this embodiment, as Figure 2 As shown, the forward sampling circuit 121 includes a first amplifier 1211 and a first filter circuit 1212. The positive input terminal of the first amplifier 1211 is connected to the output terminal of the current sensor 110, and the first filter circuit 1212 is located at the inverting input terminal and the output terminal of the first amplifier 1211. The first amplifier 1211 not only amplifies the input current signal but also performs I / V conversion, that is, converts the current signal into a positive voltage signal. The first filter circuit 1212 is responsible for signal processing and noise suppression. These two circuits cooperate to complete the forward sampling and processing of the bias voltage.

[0031] The inverting sampling circuit 122 includes a second amplifier 1221 and a second filter circuit 1222. The positive input terminal of the second amplifier 1221 is connected to the output terminal of the current sensor 110, and the second filter circuit 1222 is located at both the positive input and output terminals of the second amplifier 1221. The second amplifier 1221 not only amplifies the input current signal but also performs I / V conversion, converting the current signal into an inverted voltage signal. The second filter circuit 1222 is responsible for signal processing and noise suppression. These two circuits cooperate to complete the inverting sampling and processing of the bias voltage.

[0032] It should be noted that the first amplifier 1211 and the second amplifier 1221 here are specifically voltage comparators. They are used to sample and amplify the voltages corresponding to the positive and negative current signals output by the current sensor 110, and then output them to the adder circuit 123. The adder circuit 123 sums the positive and negative voltages of each phase line and calculates the average value to obtain the bias voltage. The summation here should be understood as summing the absolute values ​​of the sampled positive and negative voltages.

[0033] In this embodiment, the sampling unit 120 further includes a first current limiting circuit, which is disposed between the positive input terminal of the first amplifier 1211 and the output terminal of the current sensor, and between the positive input terminal of the second amplifier 1221 and the output terminal of the current sensor.

[0034] Understandably, two first current-limiting circuits are actually configured, one at the positive input terminal of the first amplifier 1211 and the other at the positive input terminal of the second amplifier 1221. These circuits limit the current flowing through the input terminals of the first amplifier 1211 and the second amplifier 1221, thereby providing protection. The parameters of these first current-limiting circuits are set according to the magnitude of the sampled voltage, and the parameters of the two circuits should be identical. Specifically, each first current-limiting circuit consists of at least one resistor.

[0035] like Figure 3 As shown, taking a three-phase motor scenario as an example, there are three phase lines A, B, and C. A current sensor is set for each phase line. The output terminal of the current sensor is connected to the input terminal of the sampling unit 120. Each phase line corresponds to a forward sampling circuit 121 and a reverse sampling circuit 122. There are three forward sampling circuits 121 and three reverse sampling circuits 122 in the figure. The forward sampling circuits 121 and reverse sampling circuits 122 in the figure are designed by amplifiers. The specific circuit structure of the forward sampling circuit 121 and reverse sampling circuit 122 of phase A is used as an example for explanation. The forward sampling circuits 121 and reverse sampling circuits 122 of phases B and C are the same as those of phase A.

[0036] The forward sampling circuit 121 and the reverse sampling circuit 122 in phase A are respectively composed of amplifiers U1 and U2, multiple resistors and capacitors. Amplifier U1, multiple resistors and two capacitors form the forward sampling circuit, and amplifier U2, multiple resistors and two capacitors form the reverse sampling circuit 122.

[0037] The specific design of the forward sampling circuit 121 is as follows: the forward input terminal of amplifier U1 is connected to the output terminal of the current sensor on phase A through a resistor. A resistor and a capacitor are connected in parallel between the inverting input terminal and the output terminal of amplifier U1 for filtering. At the same time, the output terminal of amplifier U1 is also connected to an input terminal (i.e., I / O1 in the figure) of the adder circuit 123 through a resistor. A capacitor is also provided on the output terminal of amplifier U1.

[0038] The specific design of the inverting sampling circuit 122 is as follows: the inverting input terminal of amplifier U2 is connected to the output terminal of the current sensor on phase A through a resistor. A resistor and a capacitor are connected in parallel between the inverting input terminal and the output terminal of amplifier U1. A resistor and a capacitor are connected in parallel between the non-inverting input terminal of amplifier U2 and ground for filtering. At the same time, the output terminal of amplifier U2 is connected to the other input terminal of the adder circuit 123 (i.e., I / O2 in the figure) through a resistor. A capacitor is also provided on the output terminal of amplifier U2.

[0039] In another embodiment, the forward sampling circuit 121 and the reverse sampling circuit 122 can also be designed using a sampling resistor circuit and a filter circuit. The sampling resistor circuit is connected to the output terminal of the current sensor 110, and the filter circuit is connected in parallel to the output terminal of the sampling resistor circuit to stabilize the sampling signal.

[0040] In another embodiment, the adder circuit 123 includes a third amplifier 1231 and a third filter circuit 1232; the positive input terminal of the third amplifier 1231 is connected to the output terminals of the positive sampling circuit 121 and the negative sampling circuit 122, respectively, and the negative input terminal and output terminal of the third amplifier 1231 are connected to the third filter circuit 1232, as shown below. Figure 2 As shown.

[0041] It should be noted that the third amplifier 1231 may be the same as or different from the first amplifier 1211 and the second amplifier 1221 mentioned above.

[0042] like Figure 4 As shown, the third filter circuit 1232 includes two equal-valued third resistors R3 and R4 and a capacitor C1. One third resistor R4 and the capacitor C1 are connected in parallel between the inverting input and output terminals of the third amplifier 1231. The other third resistor R3 is connected to the inverting input terminal of the third amplifier 1231 and then grounded. By combining the third resistors R3 and R4 with the capacitor C1, noise in the output signal is collected to control the amplifier's signal processing, thereby achieving a suppression effect.

[0043] Furthermore, the adder circuit 123 also includes two second current-limiting resistors R1 and R2. One second current-limiting resistor R1 is located between the output terminal of the forward sampling circuit 121 and the forward input terminal of the third amplifier 1231, and the other second current-limiting resistor R2 is located between the output terminal of the reverse sampling circuit 122 and the forward input terminal of the third amplifier 1231, thereby protecting the amplifier from the input forward and reverse voltages.

[0044] In phase A, the adder circuit 123 adds the forward voltage ADC_IA+ sampled by the forward sampling circuit 121 and the reverse voltage ADC_IA- sampled by the reverse sampling circuit 122, calculates the average value, and outputs the bias voltage.

[0045] In this embodiment, the averaging is achieved first through a voltage divider circuit. The adder circuit 123 further includes a voltage divider circuit 1233. The voltage divider circuit 1233 is located between the output terminal of the third amplifier 1231 and ground, and the output terminal of the voltage divider circuit 1233 is connected to the controller.

[0046] It should be noted that the voltage divider circuit 1233 includes a first resistor R6 and a second resistor R7 connected in series, wherein the resistance values ​​of the first resistor R6 and the second resistor R7 are equal, and the common terminal of the first resistor R6 and the second resistor R7 is connected to the controller. By setting two resistors with equal resistance values ​​and setting the sampling output point at a potential position of 1 / 2, that is, at the common terminal position of the two resistors, the average of the forward and reverse voltages can be calculated. Figure 4 R1 = R2, R3 = R4, R6 = R7. Furthermore, a resistor R5 is connected in series at the output of the third amplifier 1231. The parameters of the resistor R5 are set based on the amplification factor of the third amplifier 1231 to compensate for the difference caused by amplification, so as to ensure that the output value of the voltage divider circuit 1233 is consistent with the actual bias voltage.

[0047] By implementing the bias voltage detection circuit provided above, the device includes a current sensor and at least one sampling unit. The current sensor is used to acquire the current signal of the target device and output it to the corresponding sampling unit for sampling of forward and reverse voltages. The sampling unit includes a forward sampling circuit, a reverse sampling circuit, and an adder circuit. The forward and reverse sampling circuits are connected in parallel between the output terminal of the current sensor and the input terminal of the adder circuit. The output terminal of the adder circuit is connected to the target device or an external controller to sum the forward voltage output by the forward sampling circuit and the reverse voltage output by the reverse sampling circuit, and output a bias voltage to the controller. This solves the problem that the bias voltage output by existing current sensors is easily offset due to the influence of external factors.

[0048] This application also provides a motor control system, such as Figure 5 As shown, the system includes a bias voltage detection circuit 510, a current sensor 110, a controller 520, and a motor 530. The current sensor 110 is installed on each phase line of the motor 530. The output terminal of the adder circuit 123 is connected to the analog sampling port of the controller 520. The circuit structure of the bias detection device 510 is the same as that provided in the above embodiment, and will not be repeated here.

[0049] In this application, taking motor 530 as a three-phase motor as an example, current sensors 110 are respectively installed on the line of each phase, and the current of each line is detected by electromagnetic induction principle, so as to detect the voltage in the same way.

[0050] like Figure 3 As shown, each sampling unit 120 completes voltage sampling through the forward sampling circuit 121 and the reverse sampling circuit 122, and outputs the bias voltage to the ADC analog sampling port of the controller through the adder circuit 123. After receiving the bias voltage of each phase output by the sampling unit 120, the controller (MCU) 520 analyzes whether the bias voltage of each phase is abnormal. Here, abnormality refers to analyzing whether its offset is within the preset range. That is, if it exceeds the normal value range of (2.3V~2.7V), it can issue a warning in time to avoid unexpected motor torque, which may lead to abnormal situations such as vehicle stalling and affect driving safety.

[0051] After an early warning is issued, the system can choose to compensate or stop operation based on the analysis results. If the warning is within the acceptable range, compensation will be selected; otherwise, operation will be stopped.

[0052] The motor control system provided in this application transmits the bias voltage of the three-phase current sampling to the ADC analog sampling port of the controller through a forward sampling circuit, a reverse sampling circuit, and an adder circuit. This sampling method avoids the influence of upper and lower half-wave asymmetry caused by offset on the detection of bias voltage, ensuring that the motor controller will not deviate due to changes in the current sampling bias when generating torque output by looking up the torque-current table. Simultaneously, the controller analyzes the bias voltage of each phase for abnormalities and performs compensation based on the analysis results. This suppresses the problem of poor driving experience caused by bias voltage offset jitter.

[0053] Finally, it should be noted that the above embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A bias voltage detection circuit, characterized in that, include: Forward sampling circuit, reverse sampling circuit, and adder circuit; The forward sampling circuit and the reverse sampling circuit are connected in parallel, and their output terminals are connected to the input terminals of the adder circuit. The output of the adder circuit is connected to the target device and is used to sum the forward voltage output by the forward sampling circuit and the reverse voltage output by the reverse sampling circuit to obtain the bias voltage.

2. The bias voltage detection circuit according to claim 1, characterized in that, The forward sampling circuit includes a first amplifier and a first filter circuit; The positive input terminal of the first amplifier receives the positive voltage signal of the target device, and the first filter circuit is disposed at the inverting input terminal and the output terminal of the first amplifier.

3. The bias voltage detection circuit according to claim 1, characterized in that, The reverse sampling circuit includes a second amplifier and a second filter circuit; The inverting input terminal of the second amplifier receives the inverting voltage signal of the target device, and the second filtering circuit is located at the non-inverting input terminal and the output terminal of the second amplifier.

4. The bias voltage detection circuit according to claim 1, characterized in that, The bias voltage detection circuit further includes a first current limiting circuit, which is connected to the positive input terminal of the positive sampling circuit and to the positive input terminal of the reverse sampling circuit.

5. The bias voltage detection circuit according to any one of claims 1-4, characterized in that, The adder circuit includes a third amplifier and a third filter circuit; The positive input terminal of the third amplifier is connected to the output terminals of the positive sampling circuit and the negative sampling circuit, respectively, and the negative input terminal and the output terminal of the third amplifier are connected to the third filter circuit.

6. The bias voltage detection circuit according to claim 5, characterized in that, The third filter circuit includes two third resistors and a capacitor with equal resistance values. One third resistor and the capacitor are connected in parallel and placed between the inverting input terminal and the output terminal of the third amplifier. The other third resistor is connected to the inverting input terminal of the third amplifier and then grounded.

7. The bias voltage detection circuit according to claim 5, characterized in that, The adder circuit also includes a voltage divider circuit; The voltage divider circuit is located between the output terminal of the third amplifier and ground, and the output terminal of the voltage divider circuit is connected to the controller of the target device.

8. The bias voltage detection circuit according to claim 7, characterized in that, The voltage divider circuit includes a first resistor and a second resistor connected in series, wherein the resistance values ​​of the first resistor and the second resistor are equal, and the common terminal of the first resistor and the second resistor is connected to the target device.

9. The bias voltage detection circuit according to claim 7, characterized in that, The addition circuit also includes two second current-limiting resistors, one of which is located between the output of the forward sampling circuit and the forward input of the third amplifier, and the other is located between the output of the reverse sampling circuit and the forward input of the third amplifier.

10. A motor control system, characterized in that, The system includes: a bias voltage detection circuit, a current sensor, a controller, and a motor as described in any one of claims 1-9; The current sensor is installed on each phase line of the motor to collect the current signal of the target device and output it to the corresponding sampling unit for sampling of forward and reverse voltage; the output terminal of the adder circuit is connected to the analog sampling port of the controller.

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