Multi-channel PWM generator

Abstract

The utility model discloses a multichannel PWM generator, which comprises a PWM output circuit, the PWM output circuit comprises a PWM amplitude adjusting circuit and a PWM output driving circuit which are sequentially connected in series, and the PWM amplitude adjusting circuit comprises a filter circuit and an operational amplifier voltage follower circuit which are sequentially connected in series; one end of the filter circuit is the input end of a first PWM waveform (VolPWM1), the PWM output driving circuit comprises a triode (Q18), the base end of the triode (Q18) is the input end of a second PWM waveform (PWM2), and the collector of the triode (Q18) is connected with an output interface (J4); the operational amplifier voltage follower circuit comprises an operational amplifier voltage follower (IC20B), the output end of the filter circuit is connected to the positive input end of the operational amplifier voltage follower (IC20B), and the output end of the operational amplifier voltage follower (IC20B) is connected with the collector of the triode (Q18). According to the utility model, the output signal amplitude is continuously adjustable, and the application range is wide; and a plurality of channels can be tested independently at the same time, so that testing of a plurality of elements is completed.

Description

Technical Field

[0001] The utility model belongs to the technical field of motor control, and particularly relates to a multi-channel PWM generator.

Background Art

[0002] In the test of a direction assist motor controller, it is usually necessary to input an external corner sensor signal to verify whether the functions of the motor controller are normal. The signals of some corner sensors are output in the form of PWM waves, but currently only a few specific mid- to high-end chips can achieve this, and the prices are expensive, resulting in high production costs. Therefore, it is hoped to design a PWM generator with similar functions to achieve the same functions, and use the PWM waveform generated by this PWM generator as the input to replace the expensive corner sensor to test the direction assist motor controller.

[0003] There are similar PWM generators in the prior art. For example, a PWM generator with variable amplitude, duty cycle and frequency disclosed in Chinese Patent Grant Publication No. CN 207691770U, which is an inverting closed-loop amplifier circuit composed of an operational amplifier (U6B). The characteristic is that the output end of the inverting closed-loop amplifier circuit is connected to a feedback resistor (R33), and is connected to a resistor voltage dividing circuit composed of two resistors (R28, R31) connected to the signal input end. One end of a resistor (R31) in the resistor voltage dividing circuit is connected to the negative input end, and one end of the other resistor (R28) in the resistor voltage dividing circuit is the input end of the PWM signal; the positive input end of the inverting closed-loop amplifier circuit is connected to a resistor voltage dividing circuit connecting the power supply and the ground terminal, and the resistor voltage dividing circuit is composed of resistors (R27, R25) connected in series; this scheme changes the input duty cycle through software design, and by changing the resistance values of R25, R27, R28 and R33, the amplitude of the PWM output can be changed to obtain PWM output signals with different amplitudes. However, this scheme still has the following problems: once the circuit board is produced, to adjust the amplitude, it is necessary to replace R25, R27, R28 and R33 with different resistance values. Replacing resistors on the circuit board is cumbersome, with low efficiency and high cost, and poor versatility.

[0004] Therefore, it is necessary to provide a multi-channel PWM generator to solve the above technical problems.

Content of the Utility Model

[0005] The main purpose of the utility model is to provide a multi-channel PWM generator, whose output signal amplitude is continuously adjustable and has a wide application range; moreover, multiple channels can be independently tested simultaneously to complete the tests of multiple components.

[0006] The present utility model realizes the above object through the following technical solutions: A multi-channel PWM generator, which includes a PWM output circuit. The PWM output circuit includes a PWM amplitude adjustment circuit and a PWM output driving circuit connected in series in sequence. The PWM amplitude adjustment circuit includes a filter circuit and an operational amplifier voltage follower circuit connected in series in sequence. The filter circuit is a resistor-capacitor filter circuit and one end is the input terminal of the first PWM waveform (Vol_PWM1). The PWM output driving circuit is a triode driving circuit and includes a triode (Q18). The base terminal of the triode (Q18) is the input terminal of the second PWM waveform (PWM2), and the collector is connected to an output interface (J4). The operational amplifier voltage follower circuit includes an operational amplifier voltage follower (IC20B). The output terminal of the filter circuit is connected to the positive input terminal of the operational amplifier voltage follower (IC20B), and the output terminal of the operational amplifier voltage follower (IC20B) is connected to the collector of the triode (Q18).

[0007] Further, multiple groups of the PWM output circuits are provided and are independent of each other, and can simultaneously complete the testing of multiple devices.

[0008] Further, the resistor-capacitor filter circuit is a second-order low-pass filter circuit and is composed of a first low-pass filter circuit and a second low-pass filter circuit connected in series. The first low-pass filter circuit includes a first resistor (R23) and a first capacitor (C23) connected in series in sequence. The second low-pass filter circuit includes a second resistor (R24) and a second capacitor (C24) connected in series in sequence.

[0009] Further, a third resistor (R22) is connected in series to the negative input terminal of the operational amplifier voltage follower (IC20B). The output terminal of the third resistor (R22) is connected to the output terminal of the operational amplifier voltage follower (IC20B), and the output terminal of the operational amplifier voltage follower (IC20B) outputs a stable voltage (V_PWM).

[0010] Further, the PWM output driving circuit 3 further includes a fourth resistor (R17) connected in series to the base of the triode (Q18) and a fifth resistor (R110) connected in series between the base and the emitter of the triode (Q18).

[0011] Further, the triode (Q18) is an NPN type triode.

[0012] Further, a sixth resistor (R15) is connected in series to the collector of the triode (Q18).

[0013] Compared with the prior art, the beneficial effects of a multi-channel PWM generator of the present utility model are as follows: The provided PWM amplitude adjustment circuit can obtain different voltages V_PWM by inputting a first PWM waveform Vol_PWM1 with different duty cycles and different frequencies at the input end. This voltage is input into the PWM output driving circuit 3, and by inputting a second PWM waveform PWM2 with different duty cycles and different frequencies at the input end, the voltage change at the J4 interface is controlled to achieve the testing of the device; the duty cycle and frequency of the input first PWM waveform Vol_PWM1 can be adjusted in real time, so that different amplitude voltages can be input into the PWM output driving circuit 3, and the amplitude of the output signal is continuously adjustable, with a wide application range; in the PWM output driving circuit 3, an NPN-type triode is used to amplify the output signal, improving the driving ability of the PWM output.

Description of the Drawings

[0014] Figure 1 It is a schematic structural diagram of the PWM output circuit according to an embodiment of the present utility model;

[0015] Figure 2 It is a schematic structural diagram of the PWM amplitude adjustment circuit according to an embodiment of the present utility model;

Detailed Embodiment

[0016] Please refer to Figure 1 - Figure 2 , this embodiment is a multi-channel PWM generator. The multi-channel PWM generator includes a PWM output circuit 1. The PWM output circuit 1 includes a PWM amplitude adjustment circuit 2 and a PWM output driving circuit 3 connected in series in sequence. The PWM amplitude adjustment circuit 2 includes a filter circuit 21 and an operational amplifier voltage follower circuit 22 connected in series in sequence. The filter circuit 21 is a resistor-capacitor filter circuit, and the PWM output driving circuit 3 is a triode driving circuit.

[0017] There are multiple groups of PWM output circuits 1 and they are independent of each other, and can complete the testing of multiple devices simultaneously.

[0018] The filter circuit 21 is a second-order low-pass filter circuit, which is composed of a first low-pass filter circuit 211 and a second low-pass filter circuit 212 connected in series. The first low-pass filter circuit 211 includes a first resistor R23 and a first capacitor C23 connected in series in sequence, and the second low-pass filter circuit 212 includes a second resistor R24 and a second capacitor C24 connected in series in sequence.

[0019] Input the first PWM waveform Vol_PWM1 at the input end of the filter circuit 21. After being filtered by the filter circuit 21, a DC voltage value is output. The provided filter circuit 21 can filter out interference signals, eliminate interference, and make the voltage stable. The amplitude, frequency, and duty cycle of the first PWM waveform Vol_PWM1 are variable and can be set according to actual situations.

[0020] The operational amplifier voltage follower circuit 22 includes an operational amplifier voltage follower IC20B. The output terminal of the filter circuit 21 is connected to the positive input terminal of the operational amplifier voltage follower IC20B. A third resistor R22 is connected in series at the negative input terminal of the operational amplifier voltage follower IC20B. The output terminal of the third resistor R22 is connected to the output terminal of the operational amplifier voltage follower IC20B. The operational amplifier voltage follower IC20B outputs a stable voltage V_PWM.

[0021] The provided PWM amplitude adjustment circuit 2 can convert the first PWM waveform Vol_PWM1 into a DC voltage signal. After the signal interference is eliminated through the filtering of the filter circuit 21 to obtain a DC voltage, and then the driving ability is enhanced through the operational amplifier voltage follower circuit 22 to output a stable voltage V_PWM. This voltage V_PWM is input into the PWM output driving circuit 3. Moreover, by changing the duty cycle of the first PWM waveform Vol_PWM1, the amplitude of the output voltage V_PWM can be changed. Compared with the prior art, only by adjusting the duty cycle of the first PWM waveform Vol_PWM1 can the amplitude of the output voltage be changed. Therefore, the amplitude of the output voltage is continuously adjustable, and the operation is simple with strong applicability.

[0022] The PWM output driving circuit 3 includes a triode Q18, a fourth resistor R17 connected in series at the base of the triode Q18, and a fifth resistor R110 connected in series between the base and the emitter of the triode Q18. The collector of the triode Q18 is connected with an output interface J4.

[0023] The triode Q18 is an NPN type triode. The provided NPN type triode can amplify the signal and improve the driving ability of the PWM output driving circuit 3. The provided fourth resistor R17 can prevent the base current of the triode Q18 from being too large and burning out the triode Q18. The provided fifth resistor R110 can reduce the high-frequency gain and suppress oscillation, thereby improving the stability and frequency response of the circuit. The emitter of the triode Q18 and the reference negative terminal of the output interface J4 are commonly grounded to prevent the generation of static electricity accumulation and surge current.

[0024] The output terminal of the operational amplifier voltage follower circuit 22 is connected to the collector of the triode Q18. Therefore, the voltage V_PWM output by the operational amplifier voltage follower IC20B enters the PWM output driving circuit 3 from here. To prevent power short circuit, a sixth resistor R15 is connected in series at the collector of the triode Q18.

[0025] In this embodiment, the resistance value of the fourth resistor R17 is 10KΩ, the resistance value of the fifth resistor R110 is 4K7Ω, and the resistance value of the sixth resistor R15 is 2KΩ. In other embodiments, the above resistance values can be adjusted according to the actual application scenario.

[0026] The application principle of a multi-channel PWM generator 100 provided by this solution is as follows: A first PWM waveform Vol_PWM1 is input at the input end of the filter circuit 21. After being filtered by the filter circuit 21, a DC voltage value is output at the output end. This DC voltage value is output as a stable voltage V_PWM with enhanced driving ability through the operational amplifier voltage follower IC20B. This voltage V_PWM enters the PWM output driving circuit 3. At the same time, a second PWM waveform PWM2 is input at the base input terminal Ctrl2 of the PWM output driving circuit 3. By inputting a second PWM waveform PWM2 with different duty cycles or different frequencies, the voltage change at the J4 interface is controlled. When the second PWM waveform PWM2 at Ctrl2 is at a high level, the triode Q18 conducts, and the J4 interface outputs a low level. At this time, there is no voltage value at the J4 interface. When the second PWM waveform PWM2 at Ctrl2 is at a low level, the triode Q18 does not conduct, and the J4 interface outputs a high level, that is, the voltage value at the J4 interface is the voltage V_PWM output by the voltage follower IC20B.

[0027] Therefore, a multi-channel PWM generator 100 provided by this solution can output a PWM output signal with continuously adjustable amplitude, and multiple channels can be independently tested simultaneously to complete the testing of multiple components.

[0028] The above are only some embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A multi-channel PWM generator, characterized in that: The invention comprises a PWM output circuit (1), wherein the PWM output circuit (1) comprises a PWM amplitude adjustment circuit (2) and a PWM output drive circuit (3) which are connected in series in sequence, wherein the PWM amplitude adjustment circuit (2) comprises a filter circuit (21) and an operational amplifier voltage follower circuit (22) which are connected in series in sequence; the filter circuit (21) is a resistor-capacitor filter circuit and one end of which is an input end of a first PWM waveform (Vol_PWM1); the PWM output drive circuit (3) is a transistor drive circuit and comprises a transistor (Q18); the base end of the transistor (Q18) is an input end of a second PWM waveform (PWM2) and the collector is connected to an output interface (J4); the operational amplifier voltage follower circuit (22) comprises an operational amplifier voltage follower (IC20B); the output end of the filter circuit (21) is connected to the positive input end of the operational amplifier voltage follower (IC20B), and the output end of the operational amplifier voltage follower (IC20B) is connected to the collector of the transistor (Q18).

2. A multi-channel PWM generator as claimed in claim 1, characterized in that: The PWM output circuit (1) is provided with multiple groups which are independent of each other and can complete the testing of multiple devices at the same time.

3. A multi-channel PWM generator as claimed in claim 1, characterized in that: The RC filter circuit is a second-order low-pass filter circuit, and is composed of a first low-pass filter circuit (211) and a second low-pass filter circuit (212) connected in series, wherein the first low-pass filter circuit (211) comprises a first resistor (R23) and a first capacitor (C23) connected in series in sequence, and the second low-pass filter circuit (212) comprises a second resistor (R24) and a second capacitor (C24) connected in series in sequence.

4. A multi-channel PWM generator as claimed in claim 1, characterized in that: A third resistor (R22) is connected in series to the negative input terminal of the operational amplifier voltage follower (IC20B), an output terminal of the third resistor (R22) is connected to the output terminal of the operational amplifier voltage follower (IC20B), and the output terminal of the operational amplifier voltage follower (IC20B) outputs a stable voltage (V_PWM).

5. A multi-channel PWM generator as claimed in claim 1, characterized in that: The PWM output drive circuit (3) further comprises a fourth resistor (R17) connected in series to the base of the transistor (Q18) and a fifth resistor (R110) connected in series between the base and the emitter of the transistor (Q18).

6. A multi-channel PWM generator as claimed in claim 1, characterized in that: The transistor (Q18) is an NPN transistor.

7. A multi-channel PWM generator as claimed in claim 1, characterized in that: The collector of the transistor (Q18) is connected in series with a sixth resistor (R15).

Images