CN220823059U

CN220823059U - PWM amplitude acquisition system and charging pile

Info

Publication number: CN220823059U
Application number: CN202322456316.9U
Authority: CN
Inventors: 李波; 曹春雷; 周杨; 宋亚滨
Original assignee: Beijing Tuoyun Huiyang Technology Co ltd; Gansu Xutan New Material Co ltd
Current assignee: Beijing Tuoyun Huiyang Technology Co ltd; Gansu Xutan New Material Co ltd
Priority date: 2023-09-08
Filing date: 2023-09-08
Publication date: 2024-04-19
Anticipated expiration: 2033-09-08

Abstract

The utility model provides a PWM amplitude acquisition system and a charging pile, and relates to the technical field of CP signal detection. The PWM amplitude acquisition system comprises: a PWM generation unit for outputting a direct-current voltage signal as a PWM signal by continuous counting; the signal trigger is connected with the PWM generation unit and used for monitoring the count value of the PWM generation unit and generating an update signal when the count value reaches a first set threshold value; and the ADC collector is connected with the signal trigger and is used for responding to the update signal to sample the amplitude of the PWM signal. Compared with the prior art that PWM is converted into an effective value, the effective value voltage is collected and then the amplitude is converted according to the duty ratio, the high-level amplitude part of PWM can be directly collected, an additional conversion circuit is not needed, the collection result is stable, and the floating error is small. Meanwhile, the circuit design of the system can be simplified, and the cost is reduced.

Description

PWM amplitude acquisition system and charging pile

Technical Field

The utility model relates to the technical field of CP signal detection, in particular to a PWM amplitude acquisition system and a charging pile.

Background

Along with the development and popularization of electric automobiles, the country promulgates an alternating-current charging national standard GB_T18487.1-2015 electric automobile conduction charging system, and the standard defines a basic framework and a control guiding circuit schematic diagram of a charging equipment part, a power supply interface and an electric automobile charging part in an alternating-current charging control guiding circuit and control principle part. For example, the following states of charge are all achieved by the CP signal (Control Pilot Function control pilot function signal): the charging gun connection state in the charging process is changed, the charging of the vehicle-mounted charger is ready, the charging of the vehicle-mounted charger is completed, the charging power information is transferred, and the like. The car charging pile CP signal is a signal for controlling the charging current. In the electric vehicle charging process, the charging pile can generate a CP signal, and the signal is sent to the vehicle through a communication line between the vehicle charging socket and the vehicle to control the charging current of the electric vehicle. The corresponding states of the charging gun, such as gun pulling, gun inserting, charging preparation, charging starting and stopping, are mainly used for monitoring interaction between the charging pile and the new energy automobile, and are handshaking signals of the automobile and the charging pile.

Specifically, after the charging gun is connected to the electric vehicle, the CP signal is changed from a 12V dc signal to a 9V dc signal. Then, the main control board controls the CP signal to output a 9V PWM (Pulse Width Modulation pulse width modulation) signal with the frequency of 1KHz, wherein the duty ratio of the PWM represents the maximum output current of the charging pile. And then, the vehicle-mounted charger monitors the PWM duty ratio of the CP signal, and after confirming that the charging can be performed, the vehicle-mounted charging terminal changes the CP signal into a PWM signal of 6V. It follows that the variation in the amplitude of the CP signal corresponds to different charge control processes.

When the CP signal is a dc voltage, the amplitude of the CP signal is easily detected. However, when the CP signal is a PWM signal, in order to detect a high level voltage, the prior art generally converts the PWM signal into an effective value, collects the voltage of the effective value, and then converts the amplitude according to the duty ratio. However, the method is complex on one hand, and on the other hand, floating errors caused by integration occur in the process of converting the amplitude through the duty ratio, so that the amplitude detection result is not stable enough.

Disclosure of utility model

An object of an embodiment of the present utility model is to provide a PWM amplitude acquisition system and a charging pile, which can directly acquire a high-level amplitude of a PWM signal without an additional conversion circuit device.

In order to achieve the above object, an embodiment of the present utility model provides a PWM amplitude acquisition system, including: a PWM generation unit for outputting a direct-current voltage signal as a PWM signal by continuous counting; the signal trigger is connected with the PWM generation unit and used for monitoring the count value of the PWM generation unit and generating an update signal when the count value reaches a first set threshold value; and the ADC collector is connected with the signal trigger and is used for responding to the updating signal to sample the amplitude of the PWM signal.

Optionally, the PWM amplitude acquisition system further comprises: the PWM driving circuit is connected with the PWM generating unit and used for converting the PWM signal into a PWM signal with set voltage; and the switching circuit is connected with the PWM driving circuit and is used for outputting direct current signals or PWM signals with different voltages in different charging stages.

Optionally, the PWM driving circuit is a plurality of switches.

Optionally, the PWM signal of the set voltage is a PWM signal of ±12v.

Optionally, the direct current signals or PWM signals of different voltages include: a 12V direct current signal, a 9V PWM signal, or a 6V PWM signal, wherein the 12V direct current signal corresponds to a process in which charging control guidance is not started, the 9V PWM signal corresponds to a process in which charging control guidance is performed, and the 6V PWM signal corresponds to a process in which charging is performed.

Optionally, the PWM amplitude acquisition system further comprises a pre-processing circuit, the pre-processing circuit comprising: the isolation circuit is connected with the switching circuit; and the attenuation circuit is connected with the isolation circuit and is used for processing the PWM signal to the acquisition range of the ADC acquisition device.

Optionally, the isolation circuit is an analog optocoupler isolation circuit.

Optionally, the ADC collector further includes a filtering module, where the filtering module performs median average filtering processing on the plurality of collected values sampled by the ADC collector to obtain a target collected value.

Optionally, the ADC collector further includes a data screening module, where the data screening module screens a post-collected value of the plurality of collected values, the post-collected value is a collected value obtained by discarding a previous 1/3-2/3 of the plurality of collected values, and the filtering module performs median average filtering processing on the post-collected value of the plurality of collected values to obtain a target collected value.

In a second aspect, the utility model also provides a charging pile, which comprises the PWM amplitude acquisition system.

The beneficial effects of the utility model are as follows: compared with the prior art that PWM is converted into an effective value, the effective value voltage is collected and then the amplitude is converted according to the duty ratio, the high-level amplitude part of PWM can be directly collected, an additional conversion circuit is not needed, the collection result is stable, and the floating error is small. Meanwhile, the circuit design of the system can be simplified, and the cost is reduced.

Additional features and advantages of embodiments of the utility model will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of embodiments of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain, without limitation, the embodiments of the utility model. In the drawings:

FIG. 1 is a schematic diagram of a PWM amplitude acquisition system according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram of a PWM amplitude acquisition system according to an embodiment of the present utility model;

fig. 3 is a schematic diagram of PWM signal generation and ADC acquisition process according to an embodiment of the utility model.

Description of the reference numerals

A 100PWM amplitude acquisition system;

110PWM generating unit, 120 signal trigger, 130ADC collector;

140PWM driving circuit, 150 switching circuit;

160 pre-processing circuitry, 161 isolation circuitry, 162 attenuation circuitry.

Detailed Description

The following describes the detailed implementation of the embodiments of the present utility model with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the utility model, are not intended to limit the utility model.

An embodiment of the present utility model provides a PWM amplitude value acquisition system 100, as shown in fig. 1, the PWM amplitude value acquisition system 100 may include: PWM generation unit 110, signal trigger 120, and ADC collector 130. The signal trigger 120 may be connected to the PWM generation unit 110, and the ADC collector 130 may be connected to the signal trigger 120.

The PWM generation unit 110 may be configured to output the direct current voltage signal as the PWM signal by continuous counting. The PWM generation unit 110 may be performed according to an existing process of outputting a PWM signal. In an embodiment, the PWM generation unit 110 may be a timer module of the MCU singlechip, so that the dc signal may be processed to generate a PWM signal with a specified frequency and duty cycle, and output from a specific IO port. Wherein the duty cycle of the PWM signal represents the maximum output current of the charging pile.

The signal trigger 120 may be used to monitor the count value of the PWM generation unit and generate an update signal when the count value reaches a first set threshold. The first set threshold may be a compare register value of a timer.

The ADC collector 130 may be configured to sample the amplitude of the PWM signal in response to the update signal. In an embodiment, the ADC collector 130 may be an ADC collection interface of a single-chip microcomputer, and is configured to receive the update signal and trigger sampling of the amplitude of the PWM signal.

Compared with the prior art that PWM is converted into an effective value, the effective value voltage is collected, and then the amplitude is converted according to the duty ratio, the high-level amplitude part of PWM can be directly collected, an additional conversion circuit is not needed, the collection result is stable, and the floating error is small. Meanwhile, the circuit design of the system can be simplified, and the cost is reduced.

It should be noted that the present utility model is improved based on the existing embodiment, and the improvement point is that hardware such as a signal trigger is added, and the functions of the hardware may be implemented by elements such as an existing timer and/or a trigger (which are controlled by a very simplified existing control program), and the present utility model is not intended to improve the control program or the method.

In one embodiment, as shown in fig. 2, the PWM amplitude acquisition system 100 may further include: a PWM drive circuit 140 and a switching circuit 150. The PWM driving circuit 140 may be connected to the PWM generating unit 110, and the switching circuit 150 may be connected to the PWM driving circuit 140.

The PWM driving circuit 140 may be used to convert the PWM signal into a PWM signal of a set voltage. In one embodiment, the PWM signal of the set voltage may be a PWM signal of + -12V. That is, the PWM driving circuit 140 may convert the PWM signal generated by the timer module of the MCU singlechip into a PWM signal of ±12v.

In one embodiment, the PWM driving circuit 140 may be a plurality of switches. The voltage of the output PWM signal is controlled by the opening and closing of the plurality of switches.

In one embodiment, the switching circuit 150 may be used to output different voltages of the DC signal or PWM signal during different charging phases. For example, the direct current signals or PWM signals of different voltages may include: a direct current signal of 12V, a PWM signal of 9V, or a PWM signal of 6V, and the direct current signal of 12V corresponds to a process in which the charge control guidance is not started, the PWM signal of 9V corresponds to a process in which the charge control guidance is started, and the PWM signal of 6V corresponds to a process in which the charge is performed.

Specifically, the switching circuit 150 may be a DC/PWM switching circuit controlled by the MCU, and the DC/PWM switching circuit may be used to perform the following functions:

1) Switching and outputting a 12V direct current signal in the process of not starting charging control guidance;

2) In the process of charging control guidance, switching and outputting a 9V PWM signal;

3) During charging, the PWM signal of 6V is switched and output.

It should be appreciated that the switching circuit may be virtually any device capable of achieving voltage switching. In one embodiment, the switching circuit 150 may be a plurality of switches. The type and voltage of the output PWM signal are controlled by the opening and closing of the plurality of switches.

In one embodiment, as shown in FIG. 2, the PWM amplitude acquisition system 100 may further include a pre-processing circuit 160. The pre-processing circuit 160 may include: an isolation circuit 161 and an attenuation circuit 162. The isolation circuit is connected with the switching circuit, and the attenuation circuit is connected with the isolation circuit.

In this embodiment, the isolation circuit 161 and the attenuation circuit 162 together form a front-end part of the ADC collector. The isolation circuit 161 can protect and reduce interference. In one embodiment, the isolation circuit may be an analog optocoupler isolation circuit. The attenuation circuit 162 may be used to process the PWM signal into the collection range of the ADC collector, that is, the attenuation circuit 162 is capable of processing the dc/PWM signal output via the switching circuit 150 into the collection range of the ADC collector and reducing the input impedance of the dc/PWM signal input to the ADC collector.

Fig. 3 shows a process of how PWM signals are generated inside the MCU monolithic processor. Wherein, setting the timer to the PWM output mode, the input clock frequency and the auto-load value of the timer may determine the frequency of the PWM wave to be generated. Meanwhile, a first set threshold value and a second set threshold value may be set, wherein the first set threshold value may be a comparison register value of a timer, which is capable of determining a duty ratio of a PWM wave to be generated. When the value of the counter of the timer is smaller than the comparison register value, the PWM signal is output as a high level. When the value of the counter of the timer is greater than or equal to the comparison register value, the PWM signal is output as a low level. In addition, the second set threshold may be an auto-load register value of the timer, and after the value of the counter of the timer is greater than the auto-load register value, an update signal (also referred to as an update event) may be generated and the counter of the timer is zeroed.

Based on the above principle of PWM signal generation, referring to fig. 3, the steps from generating the PWM signal to the ADC collector performing the collection are as follows:

1) The counter of the timer continuously counts;

2) PWM outputs high level, when the counter of the timer is smaller than the comparison register value of the timer, the high level is output;

3) PWM outputs low level, when the counter of the timer is larger than or equal to the comparison register value of the timer, the low level is output;

4) After the counter of the timer reaches the value of the automatic loading register, the counter is reset to zero, and an automatic updating event is generated;

5) The ADC collector waits for an update event and is driven by the update event generated by the timer to trigger one sampling when the update event is detected.

It can be seen that the start-up conversion of the ADC collector is set to be triggered by the update event of the timer, and since the timer returns to zero when the update event is generated, the PWM output is necessarily high, and the ADC collector samples at the time triggered by the update event, the collected PWM signal is also necessarily in the high period. And then, converting the acquisition value of the ADC acquisition unit to obtain the PWM high-level amplitude value of the current CP signal.

It should be noted that if the CP signal is output as DC direct voltage, since there is no low level in the DC state, the data collected by the ADC collector is also high level data, and the PWM amplitude collecting system and steps described above can also be used to measure the target amplitude. Therefore, the scheme is simultaneously suitable for amplitude acquisition of the direct current signal and the PWM signal. The acquisition operation of the ADC acquisition unit does not need to be stopped, since the timer is generating PWM waves all the time and an update event is generated every PWM period.

In addition, the inventors have found that in implementing this embodiment, there may be an overcharge phenomenon at the rising edge of the PWM due to the parasitic capacitance in the actual circuitry. Specifically, in the actual sampling process, because of the existence of the capacitive reactance of the circuit when the PWM signal jumps from low level to high level, the overcharge phenomenon exists in a short period of time from the high level, namely the amplitude is higher or lower than the actual high level amplitude, the oscillation after a period of time tends to be stable, a certain error exists in the sampling result immediately after the timer updating event occurs, and the acquired value is inaccurate. The inventors have calculated that the value acquired at the first time after the ADC is updated event will be higher.

In this regard, in one embodiment, the ADC collector may also be configured to sample the PWM signal multiple times and obtain a target collection value from among the multiple collection values. For example, the ADC collector may further include a filtering module configured to perform median average filtering processing on the plurality of collected values sampled by the ADC collector to obtain a target collected value.

In another embodiment, when the ADC collector is triggered by an update event, multiple sets of values may also be set, a portion of the data sampled earlier is discarded to avoid the unstable phase, and the next sets of samples are taken to avoid overcharging. The acquisition value can be made closer to the true value. For example, the ADC collector may further include a data screening module configured to screen a post-acquisition value of the plurality of acquisition values, where the post-acquisition value may be an acquisition value that has discarded a first 1/3-2/3 of the plurality of acquisition values. The median average filtering can then be performed on the post-sampled data in the plurality of acquisition values by a filtering module to obtain a more accurate target sample value.

The beneficial effects of the charging pile can be referred to the description of the PWM amplitude acquisition system, and are not repeated here.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.

Claims

1. A PWM amplitude acquisition system, comprising:

a PWM generation unit for outputting a direct-current voltage signal as a PWM signal by continuous counting;

The signal trigger is connected with the PWM generation unit and used for monitoring the count value of the PWM generation unit and generating an update signal when the count value reaches a first set threshold value; and

And the ADC collector is connected with the signal trigger and is used for responding to the updating signal to sample the amplitude of the PWM signal.

2. The PWM amplitude acquisition system according to claim 1, further comprising:

The PWM driving circuit is connected with the PWM generating unit and used for converting the PWM signal into a PWM signal with set voltage; and

And the switching circuit is connected with the PWM driving circuit and is used for outputting direct current signals or PWM signals with different voltages in different charging stages.

3. The PWM amplitude acquisition system of claim 2, wherein the PWM drive circuit is a plurality of switches.

4. The PWM amplitude acquisition system according to claim 2, wherein the PWM signal of the set voltage is a PWM signal of ±12v.

5. The PWM amplitude acquisition system of claim 4, wherein the dc signals or PWM signals of different voltages comprise: a 12V direct current signal, a 9V PWM signal, or a 6V PWM signal, wherein the 12V direct current signal corresponds to a process in which charging control guidance is not started, the 9V PWM signal corresponds to a process in which charging control guidance is performed, and the 6V PWM signal corresponds to a process in which charging is performed.

6. The PWM amplitude acquisition system of claim 2, further comprising a pre-processing circuit, the pre-processing circuit comprising:

The isolation circuit is connected with the switching circuit; and

And the attenuation circuit is connected with the isolation circuit and is used for processing the PWM signal to the acquisition range of the ADC acquisition device.

7. The PWM amplitude acquisition system of claim 6, wherein the isolation circuit is an analog optocoupler isolation circuit.

8. The PWM amplitude acquisition system of claim 1, wherein the ADC acquisition further comprises a filtering module that performs median average filtering processing on the plurality of acquisition values sampled by the ADC acquisition to obtain a target acquisition value.

9. The PWM amplitude acquisition system of claim 8, wherein the ADC acquisition further comprises a data screening module that screens post-acquisition values of the plurality of acquisition values, wherein the post-acquisition values are acquisition values that have discarded the first 1/3-2/3 of the plurality of acquisition values, and wherein the filtering module performs median average filtering on post-acquisition values of the plurality of acquisition values to obtain a target acquisition value.

10. A charging pile, characterized in that it comprises a PWM amplitude acquisition system according to any one of claims 1-9.