CN111551811A - A detection circuit, device and charging equipment for output state of charging equipment - Google Patents

Abstract

The invention discloses a detection circuit for the output state of charging equipment, which comprises a PWM control unit, a first resistor, a second resistor, a reference voltage source, an error amplifier, a first capacitor, a comparator and a reference voltage source, wherein the reference voltage source is connected with the first resistor; the PWM control unit receives a voltage signal at an input end and outputs a modulated voltage signal; one end of the first resistor is connected with the output end of the PWM control unit, and the other end of the first resistor is grounded after being connected with the second resistor in series; the first resistor is also connected with the input end of the error amplifier; the reference voltage source is also connected with the input end of the error amplifier; the error amplifier outputs an error voltage signal; the first capacitor is connected with the error amplifier and the PWM control unit; the input end of the comparator is connected with the first capacitor, the error amplifier and a reference voltage source; the detection device of output state and battery charging outfit are still disclosed. The invention realizes the prompt function of charging completion without detecting the periphery, and greatly reduces the cost of an external device, the board distribution area of a PCB and the power consumption of the device.

Description

A detection circuit, device and charging equipment for output state of charging equipment

technical field

The invention relates to the field of detection circuits for the output state of charging equipment, in particular to a detection circuit, device and charging equipment for the output state of charging equipment.

Background technique

General DC chargers (such as car chargers) only have a charging power indicator, which can only show whether the power is connected, but not whether the charging is full. Know the charging status.

At present, if you want to reflect the charging state, the detection method of adding a current sampling resistor is often used, and the output current is always detected through the current sampling resistor. The detection signal needs to be amplified by a precision operational amplifier. When the output current is reduced to a certain current ( Such as 200mA), the operational amplifier is turned over, resulting in a turn light (such as a green light to a red light). The use of this detection method requires additional access to a current sampling resistor, which has the problems of high power consumption, complex peripherals, occupying a large area of the printed circuit board (PCB), and high cost, and this detection method is not conducive to the integration of the device, especially for small and small For cigarette lighter chargers, the area of the PCB is very important.

SUMMARY OF THE INVENTION

In view of the above problems, an object of the present invention is to provide a detection circuit for the output state of a charging device. The present invention samples the output current proportionally, and integrates the output DC voltage through an error amplifier. The output DC voltage is proportional to the output current at the output end of the charging device. (charging current), the size of the charging current is obtained, and this voltage can be used to control the turning lights or sound; the present invention realizes the detection of the output current of the charging equipment without any detection peripheral (current sampling resistor), greatly External device cost, PCB layout area, and device power consumption are reduced.

The second object of the present invention is to provide a detection device for the output state of a charging device. The detection device provided by the present invention can be fully or partially integrated in a chip, which is beneficial to the integration of the device and is more suitable for portable charging with small PCB area. device.

The third object of the present invention is to provide a charging device, which has a prompt function of charging completion.

The first technical solution adopted by the present invention is: a detection circuit for the output state of a charging device, comprising a PWM control unit, a first resistor, a second resistor, a reference voltage source, an error amplifier, a first capacitor, a comparator and a reference power source;

The PWM control unit is used for receiving the voltage signal of the input terminal and outputting the modulated voltage signal;

One end of the first resistor is connected to the output end of the PWM control unit, and the other end is connected to the second resistor in series and then grounded; the first resistor is also connected to the input end of the error amplifier;

The reference voltage source is also connected to the input end of the error amplifier for outputting a reference voltage signal;

The error amplifier performs operational amplification on the reference voltage signal and the signal divided by the first resistor, and outputs an error voltage signal;

The first capacitor is connected to the error amplifier and the PWM control unit, and generates a DC voltage signal according to the error voltage signal;

The input end of the comparator is connected to the first capacitor, the error amplifier and the reference voltage source, and is used to compare the reference voltage signal output by the reference voltage source with the DC voltage signal, and determine the charging state of the charging device according to the comparison result .

Preferably, the detection circuit further includes a low-pass filtering unit, the low-pass filtering unit is connected between the error amplifier and the comparator, and is configured to perform low-pass filtering on the DC voltage signal.

Preferably, the low-pass filtering unit includes a third resistor, a first switch, a second capacitor, a fourth resistor, a second switch, a third capacitor and a switch control unit; the switch control unit connects the first switch and the second switch switch, one end of the third resistor is connected to the first capacitor, the other end is connected to the first switch, the other end of the first switch is connected to the second capacitor, the second capacitor is connected to the fourth resistor, and the other end of the fourth resistor A second switch is connected, the second switch is connected to a third capacitor, and the voltage of the third capacitor is the final output voltage of the low-pass filtering unit.

Preferably, both the first switch unit and the second switch unit are gate circuits.

Preferably, the error amplifier is a transconductance amplifier.

Preferably, when the DC voltage signal is greater than the reference voltage signal, it is determined that charging is in progress; when the DC voltage signal is smaller than the reference voltage signal, it is determined that charging is complete.

Preferably, the reference voltage source outputs a high voltage signal VH and a low voltage signal VL; when the DC voltage signal is lower than VL, it indicates that charging is completed; when the DC voltage signal is higher than VH, it indicates that charging is not completed .

The second technical solution adopted by the present invention is: a detection device for an output state of a charging device, comprising the detection circuit according to any one of the first technical solutions and an execution device connected to the detection circuit; the detection circuit The actuator is driven by at least one drive unit.

Preferably, the execution device includes a display device or/and a sound device.

The third technical solution adopted by the present invention is: a charging device, comprising the detection device according to any one of the second technical solutions.

The beneficial effects of the above technical solutions:

(1) The present invention realizes the detection of the output current of the charging equipment without any detection peripheral (current sampling resistor), and greatly reduces the cost of external devices, the layout area of the PCB and the power consumption of the device.

(2) The detection device provided by the present invention realizes the prompt function of charging completion (turning the light or/and sounding) without any detection peripheral (current sampling resistor), which greatly reduces the cost of the external device and the layout area of the PCB. and power consumption of the device.

(3) The detection device provided by the present invention can be fully or partially integrated in a chip, which is beneficial to the integration of the device, and is more suitable for portable chargers with small PCB area.

(4) The charging device disclosed in the present invention has a prompt function of charging completion, and the prompt function is turning lights or/and making sounds.

Description of drawings

1 is a schematic structural diagram of a detection circuit for an output state of a charging device according to the present invention;

2 is a schematic structural diagram of a low-pass filter unit in the present invention;

3 is a schematic structural diagram of a device for detecting an output state of a charging device according to the present invention.

Detailed ways

The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principle of the present invention by way of example, but not to limit the scope of the present invention, that is, the present invention is not limited to the described preferred embodiments, and the scope of the present invention is defined by the claims. limited.

Many specific details are set forth in the following description to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can do so without departing from the connotation of the present invention. Similar promotion, therefore, the present invention is not limited by the specific embodiments disclosed below.

Second, reference herein to "one embodiment" or "an embodiment" refers to a particular feature, structure, or characteristic that may be included in at least one implementation of the present invention. The appearances of "in one embodiment" in various places in this specification are not all referring to the same embodiment, nor are they separate or selectively mutually exclusive from other embodiments.

In the description of the present invention, it should be noted that, unless otherwise specified, "a plurality of" means two or more; The relationships are only for convenience in describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," etc. are used for descriptive purposes only and should not be construed to indicate or imply relative importance. The orientation words appearing in the following description are all the directions shown in the drawings, and do not limit the specific structure of the present invention. In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrally connected; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances, and for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Example 1

As shown in FIG. 1 , the present invention discloses a detection circuit for the output state of a charging device, including a PWM control unit, a first resistor, a second resistor, a reference voltage source, an error amplifier, a first capacitor, a comparator and a reference voltage source The PWM control unit is used to receive the voltage signal of the input terminal and output the modulated voltage signal; one end of the first resistor is connected to the output end of the PWM control unit, and the other end is connected to the second resistor in series and then grounded; the first resistor is also connected to the error amplifier The reference voltage source is also connected to the input end of the error amplifier for outputting the reference voltage signal; the error amplifier performs error amplification on the reference voltage signal and the signal divided by the first resistor, and outputs the error voltage signal The first capacitor is connected to the error amplifier and the PWM control unit, and generates a DC voltage signal according to the error voltage signal; The voltage signals are compared, and the charging state of the charging device is determined according to the comparison result. The error amplifier is, for example, a transconductance amplifier.

As shown in Figure 1, the input voltage of the input terminal Vin of the charging device is a DC voltage (such as the battery voltage inside the car, 8-40V). The pulse width modulation (PWM) control unit includes an energy conversion element inductor L and an output capacitor Cout, PWM The control unit receives the input voltage signal from the input terminal Vin, converts the input voltage signal through the energy conversion element inductance L, and outputs the voltage signal Vout through the output capacitor Cout; the PWM control unit is, for example, a DC-DC controller, working in a peak current mode.

The output voltage signal Vout is divided by the first resistor and the second resistor to form a resistor-divided signal, which is connected to the negative end of the error amplifier, the positive end of the error amplifier is connected to the reference voltage source, the reference voltage source outputs the reference voltage signal, and the error amplifier receives The reference voltage signal and the resistive voltage division signal are subjected to error amplification to generate an error voltage signal, and the error voltage signal is output to the first capacitor C to generate a first DC voltage signal to reflect the state of the output current of the charging device; the first capacitor C Connected to the PWM control unit, the first DC voltage signal controls the PWM control unit. The error amplifier is, for example, a transconductance amplifier.

When the output current of the charging device decreases, since the output current of the PWM control unit is too late to respond, the device output voltage Vout increases. Vice versa, when the output current of the device increases, Vout decreases.

When Vout increases, the resistive voltage division generated by the first resistor and the second resistor increases, the output voltage of the error amplifier decreases, that is, the DC voltage of the first capacitor C decreases, and the output current of the PWM control unit decreases. On the contrary, when Vout decreases, the resistance division generated by the first resistor and the second resistor decreases, the output voltage of the error amplifier increases, that is, the DC voltage of the first capacitor C increases, and the output current of the PWM control unit increases; after repeated cycles, the PWM The change of the output current of the control unit is consistent with the change of the charging current of the charging device and remains stable.

Therefore, when the output current of the device increases, that is, when the charging current increases, the DC voltage of the first capacitor increases; when the output current decreases, that is, when the charging current decreases, the DC voltage of the first capacitor decreases; so the first capacitor The DC voltage of the charging device is proportional to the size of the output current of the device, which can reflect the state of the output current of the output terminal of the charging device.

The DC voltage of the first capacitor is Vc, the output current is Iout, and the corresponding internal proportional coefficient is a fixed value k, Vc=k·Iout; therefore, by detecting the Vc voltage, the magnitude of the output current can be accurately reflected.

Further, in one embodiment, the detection circuit further includes a low-pass filter unit, the low-pass filter unit is electrically connected to the first capacitor, the DC voltage signal output by the first capacitor is filtered and processed by the low-pass filter unit, and the filtered DC voltage signal is output. The voltage is proportional to the charging current charged by the external device, so the size of the charging current is obtained, that is, the output of the low-pass filter unit also reflects the state of the output current at the output terminal. The ripple of the DC voltage signal generated by the first capacitor is about 40mV, and the ripple of the DC voltage after low-pass filtering is lower than 2mV; the DC voltage after low-pass filtering is the output voltage of the final filter, and its DC component is the same as the first one. The DC components of the capacitors are the same. After the low-pass filter unit, the ripple is reduced from 40mV to less than 2mV, and the DC component (DC voltage) of the first capacitor is more accurately detected.

As shown in FIG. 2 , the low-pass filtering unit includes a third resistor, a first switch, a second capacitor, a fourth resistor, a second switch, a third capacitor, and a switch control unit.

The switch control unit is electrically connected to the first switch unit and the second switch unit, one end of the third resistor is electrically connected to the first capacitor, the other end is electrically connected to the first switch, and the other end of the first switch is electrically connected to the first switch. Two capacitors, the voltage output of the second capacitor is the output of the first stage of the filter, the second capacitor is electrically connected to the fourth resistor, and the other end of the fourth resistor is electrically connected to the second switch, so The second switch is electrically connected to the third capacitor, and the voltage of the third capacitor is the final output voltage of the low-pass filtering unit.

Both the first switch unit and the second switch unit are gate circuits; the ratio of the turn-on and turn-off time of the first switch unit in one cycle is 1:n, so that the third resistance can be amplified by n times; The ratio of the turn-on time to turn-off time of the switch unit in one cycle is 1:m, so that the fourth resistance can be amplified by m times.

In this embodiment, the first switch unit is a gate circuit, and the ratio of the turn-on time to turn-off time of the gate gate in one cycle is 1:100, so that the third resistance can be amplified by 100 times; In the pass-gate circuit, the ratio of the turn-on and turn-off time of the gate in one cycle is 1:100, and the fourth resistor is amplified by 100 times. Let the third resistor be R3, the second capacitor be C2, the fourth resistor be R4, and the third capacitor be C3.

The first-stage filtering time constant is: 101·R3·C2, and the second-stage filtering time constant is: 101·R4·C3; after two-stage low-pass filtering, the voltage of the third capacitor is the final filter output voltage, and its DC The component is the same as the DC component of the first capacitor, the ripple is lower than 2mV, and the DC component (DC voltage) of the first capacitor is detected more accurately.

The detection circuit of the output state of the charging device includes a comparator and a reference voltage source; the negative terminal of the comparator is electrically connected to the output terminal of the error amplifier or the output terminal of the low-pass filtering unit. The comparator is connected to the reference voltage source, and the comparator is used to compare the reference voltage signal output by the reference voltage source with the DC voltage signal output by the low-pass filtering unit, and output the comparison result signal, which is used to determine the charging state. Since the DC voltage signal is proportional to the charging current charged by the external device, the magnitude of the charging current is obtained. Therefore, a comparator is set to compare the DC voltage signal with the reference voltage signal to determine the charging state of the charging device. When the DC voltage signal is greater than the reference voltage When the signal is detected, it is determined that charging is in progress; when the DC voltage signal is less than the reference voltage signal, it is determined that the charging is completed.

The reference voltage source switches between the high reference voltage VH and the low reference voltage VL; when the output voltage of the low-pass filter unit is lower than VL, it indicates that the output current is reduced to IL, that is, the charging current is reduced to IL, and the charging has been completed, here In the present invention, for example, IL is set to 200mA (but not limited to this); when the output voltage of the low-pass filter unit is higher than VH, it indicates that the output current increases to IH, the charging current increases to IH, and the charging is not completed. Here, the present invention is for example Set IH to 600mA (but not limited to this).

The present invention adopts the method of integrating the output of the internal sampling error amplifier to sample the magnitude of the output current, which is filtered and processed by the low-pass filtering unit to output the corresponding DC voltage, which is proportional to the charging current of the charging equipment, and thus the charging current is obtained. the size of.

As shown in FIG. 3 , an output state detection device disclosed in the present invention includes the above-mentioned detection circuit and an execution device electrically connected to the detection circuit; the execution device includes a display device or/and a sounding device; the detection circuit is driven by at least one The unit drives the above-mentioned executing device, that is, the output end of the comparator in the detection circuit is electrically connected to the driving unit, and the driving unit drives the executing device. The detection circuit can drive the display device through the display driving unit, and the display device can be selected from LED lamps; the detection circuit can drive the sound-emitting device through the sound-emitting driving unit, and the sound-emitting device can be selected from a speaker.

The reference voltage source is switched between the reference voltage VH and the reference voltage VL, and the reference voltage signal output by the reference voltage source is compared with the output voltage signal of the low-pass filtering unit through the comparator. When the output voltage of the low-pass filter unit is lower than VL, it indicates that the output current is reduced to IL, that is, the charging current is reduced to IL (for example, 200mA), which represents the charging completion state, and the comparator outputs the comparison result signal, which controls the display The drive unit drives the LED light to change from red to green or/and the drive unit drives the speaker to give a voice prompt to complete the charging; when the output voltage of the low-pass filter unit is higher than VH, it indicates that the output current increases to IH, that is, the charging current increases to IH (for example, 600mA), at this time, it represents the state of being charged and not fully charged. The comparator outputs a comparison result signal, which controls the display drive unit to drive the LED light to display a red light or/and the sound drive unit drives the speaker. The voice prompts that charging is in progress .

The invention adopts the integral output method of the internal sampling error amplifier to sample the magnitude of the output current, which is filtered by the low-pass filtering unit to output the corresponding DC voltage, which is proportional to the charging current of the external device, and thus the charging current is obtained. the magnitude of the current. The present invention realizes the prompt function of charging completion (LED lights turn lights or/and voice prompts) without any detection peripheral, and greatly reduces the cost of external devices and the layout area of the PCB.

The detection device provided by the present invention realizes the prompt function of charging completion (turning the light or/and sounding) without any detection peripheral (current sampling resistor), which greatly reduces the cost of the external device, the layout area of the PCB, and the cost of the device. Moreover, the detection device provided by the present invention can be fully or partially integrated in one chip, which is beneficial to the integration of the device, and is more suitable for portable chargers with small PCB area.

The invention discloses a charging device, comprising the above-mentioned detection device; the charging device has a prompt function of charging completion, and the prompt function is to turn lights or/and to sound.

While the present invention has been described with reference to the preferred embodiments, various modifications may be made and equivalents may be substituted for parts thereof without departing from the scope of the invention. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any manner. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims (10)

1. A detection circuit for an output state of a charging device, comprising a PWM control unit, a first resistor, a second resistor, a reference voltage source, an error amplifier, a first capacitor, a comparator and a reference voltage source; The PWM control unit is used for receiving the voltage signal of the input terminal and outputting the modulated voltage signal; One end of the first resistor is connected to the output end of the PWM control unit, and the other end is connected to the second resistor in series and then grounded; the first resistor is also connected to the input end of the error amplifier; The reference voltage source is also connected to the input end of the error amplifier for outputting a reference voltage signal; The error amplifier performs operational amplification on the reference voltage signal and the signal divided by the first resistor, and outputs an error voltage signal; The first capacitor is connected to the error amplifier and the PWM control unit, and generates a DC voltage signal according to the error voltage signal; The input end of the comparator is connected to the first capacitor, the error amplifier and the reference voltage source, and is used to compare the reference voltage signal output by the reference voltage source with the DC voltage signal, and determine the charging state of the charging device according to the comparison result . 2 . The detection circuit according to claim 1 , further comprising a low-pass filtering unit, the low-pass filtering unit is connected between the error amplifier and the comparator, and is used for performing the filtering on the DC voltage signal. 3 . low pass filtering. 3. The detection circuit according to claim 2, wherein the low-pass filtering unit comprises a third resistor, a first switch, a second capacitor, a fourth resistor, a second switch, a third capacitor and a switch control unit ; The switch control unit is connected to the first switch and the second switch, one end of the third resistor is connected to the first capacitor, the other end is connected to the first switch, the other end of the first switch is connected to the second capacitor, the second capacitor A fourth resistor is connected, the other end of the fourth resistor is connected to a second switch, the second switch is connected to a third capacitor, and the voltage of the third capacitor is the final output voltage of the low-pass filtering unit. 4 . The detection circuit according to claim 3 , wherein the first switch unit and the second switch unit are both gate circuits. 5 . 5. The detection circuit according to claim 1, wherein the error amplifier is a transconductance amplifier. 6 . The detection circuit according to claim 1 , wherein when the DC voltage signal is greater than the reference voltage signal, it is determined that charging is in progress; when the DC voltage signal is smaller than the reference voltage signal, it is determined that charging is complete. 7 . 7. The detection circuit according to claim 1, wherein the reference voltage source outputs a high voltage signal VH and a low voltage signal VL; when the DC voltage signal is lower than VL, it indicates that charging has been completed; When the DC voltage signal is higher than VH, it indicates that the charging is not completed. 8 . A detection device for an output state of a charging device, comprising: the detection circuit according to any one of claims 1 to 7 and an execution device connected to the detection circuit; the detection circuit is driven by at least one The unit drives the actuator. 9 . The detection device according to claim 8 , wherein the execution device comprises a display device or/and a sounding device. 10 . 10. A charging device, characterized by comprising the detection device according to claim 8 or 9.

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