PWM detection circuit

Abstract

The utility model relates to the technical field of battery thermal management, in particular to a PWM (Pulse Width Modulation) detection circuit, which comprises a current-limiting voltage-dividing circuit, a voltage-limiting circuit, a secondary isolation shaping circuit, an RC (Resistance-Capacitance) filter circuit and a microcontroller which are connected in sequence, and is characterized in that the current-limiting voltage-dividing circuit comprises a first resistor and a fourth resistor which are connected with each other and is connected with a first capacitor in parallel; the voltage limiting circuit comprises a first diode and a second resistor which are connected with each other, the cathode of the first diode is connected with the first resistor and the fourth resistor, the anode of the first diode is connected with the second resistor, and the other end of the second resistor is connected with an input voltage; the secondary isolation shaping circuit comprises a first Schmidt inverter and a second Schmidt inverter which are connected with each other. The circuit has the advantages of simple structure and reasonable design, can effectively reduce the mass production cost, and improves the product reliability.

Description

Technical Field

[0001] The utility model relates to the technical field of battery thermal management, in particular to a PWM detection circuit. Background Art

[0002] The battery pack is a critical component of new energy vehicle systems, providing power for the entire vehicle. Since the battery pack generates high temperatures during operation, uncontrolled operation can easily lead to fire or damage. To ensure safe and reliable battery pack operation, many vehicles now incorporate battery thermal management features. One such feature uses liquid circulation technology to lower the battery pack's temperature. This technology utilizes PWM control of the battery pack's water pump. This utilizes the vehicle's control system to monitor the battery pack's ambient temperature. Once the required temperature is met, a PWM wave is generated to adjust the pump's liquid circulation speed, ensuring the battery pack operates within a reasonable temperature range.

[0003] Among them, battery pack PWM technology, as an efficient analog control technology, plays an important role in battery management and control. By adjusting parameters such as pulse width and duty cycle, precise control of battery pack output voltage, current and other parameters can be achieved, improving the safety and efficiency of battery use. However, using PWM to regulate the battery pack water pump also has a disadvantage. After the PWM wave is emitted, it is difficult to determine whether the water pump is fully executed and whether the PWM fault transmitted by the water pump is effectively handled. If this is not detected in time, the battery pack will overheat or operate at a low temperature, which will reduce the battery pack's efficiency and create safety risks.

[0004] The existing circuit for inputting the water pump PWM signal into the microcontroller is not only complex in structure, but also has poor signal processing effect. It cannot provide the microcontroller with accurate water pump PWM signal, which in turn affects the microcontroller's accurate monitoring of the battery pack.

[0005] Therefore, a new technical solution is urgently needed to solve the above technical problems. Utility Model Content

[0006] The purpose of the present utility model is to overcome the problems of the above-mentioned prior art and provide a PWM detection circuit to solve the technical problem that the existing circuit for inputting the water pump PWM signal into the microcontroller is not only complex in structure, but also has poor signal processing effect and cannot provide the microcontroller with accurate water pump PWM signal, thereby affecting the microcontroller's accurate monitoring of the battery pack.

[0007] The above objectives are achieved through the following technical solutions:

[0008] A PWM detection circuit includes a current limiting and voltage divider circuit, a voltage limiting circuit, a secondary isolation and shaping circuit, an RC filter circuit, and a microcontroller connected in sequence. The current limiting and voltage divider circuit includes a first resistor and a fourth resistor connected to each other and connected in parallel with a first capacitor. The voltage limiting circuit includes a first diode and a second resistor connected to each other, the cathode of the first diode connected to the first resistor and the fourth resistor, the anode of the first diode connected to the second resistor, and the other end of the second resistor connected to an input voltage. The secondary isolation and shaping circuit includes a first Schmidt inverter and a second Schmidt inverter connected to each other, the level input end of the first Schmidt inverter connected to the voltage limiting circuit, the level output end of the first Schmidt inverter connected to the level input end of the second Schmidt inverter, and the level output end of the second Schmidt inverter connected to the RC filter circuit.

[0009] Furthermore, a second capacitor is connected to the same end of the first diode and the second resistor.

[0010] Furthermore, the model of the second capacitor is 10pf / 50V.

[0011] Furthermore, the RC filter circuit includes a third resistor and a third capacitor connected to each other, one end of the third resistor is connected to the level output end of the second Schmitt inverter, and the other end is connected to the microcontroller.

[0012] Furthermore, the model of the third resistor is 100R / 1%, and the model of the third capacitor is 100pf / 50V.

[0013] Furthermore, the model of the first resistor is 4.7K / 1%.

[0014] Furthermore, the model of the second resistor is 100K / 1%.

[0015] Furthermore, the model of the fourth resistor is 10K / 1%.

[0016] Furthermore, the model of the first capacitor is 4.7nF / 100V.

[0017] Furthermore, the first Schmitt inverter and the second Schmitt inverter both adopt SN74HC14 Schmitt inverters.

[0018] The PWM detection circuit provided by this utility model has the advantages of simple structure and rational design, effectively reducing mass production costs and improving product reliability. Furthermore, it has voltage and current limiting functions, enabling real-time monitoring of the water pump PWM signal and timely and accurate input to the microcontroller for processing. Any abnormality in the PWM frequency or duty cycle is immediately detected, avoiding the safety hazard of low or high temperature operation of the battery pack and improving the battery pack's efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a module framework diagram of a PWM detection circuit described in the present utility model;

[0020] Figure 2 This is a circuit diagram of a PWM detection circuit described in the utility model. DETAILED DESCRIPTION

[0021] The present invention is further described below with reference to the accompanying drawings and examples. The described embodiments are only a portion of the embodiments of the present invention, and are not intended to be exhaustive. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0022] like Figure 1 and 2 As shown, this solution provides a PWM detection circuit, including a current limiting and voltage divider circuit, a voltage limiting circuit, a secondary isolation shaping circuit, an RC filter circuit, and a microcontroller connected in sequence. The current limiting and voltage divider circuit includes a first resistor R1 and a fourth resistor R4 connected to each other for voltage division, and is connected in parallel with a first capacitor C1 for current limiting. The voltage limiting circuit includes a first diode D1 and a second resistor R2 connected to each other, wherein the cathode of the first diode D1 is connected to the first resistor R1 and the fourth resistor R4, the anode of the first diode D1 is connected to the second resistor R2, and the other end of the second resistor is connected to the input voltage VCC.

[0023] The secondary isolation shaping circuit includes a first Schmitt inverter U1C and a second Schmitt inverter U1D connected to each other, the level input end of the first Schmitt inverter U1C is connected to the voltage limiting circuit, the level output end of the first Schmitt inverter U1C is connected to the level input end of the second Schmitt inverter U1D, and the level output end of the second Schmitt inverter U1D is connected to the RC filter circuit.

[0024] Working principle:

[0025] The water pump PWM signal is input from the INPUT end of the circuit in real time, processed by the current limiting and voltage dividing circuit to achieve voltage division, then subjected to voltage limiting processing by the voltage limiting circuit to obtain a limited voltage, and then subjected to secondary waveform rectification by the secondary isolation and shaping circuit. Finally, it is filtered by the RC filter circuit and input into the microcontroller. The microcontroller analyzes the received PWM signal to obtain the corresponding frequency and duty cycle, thereby determining whether the current device is operating normally.

[0026] Specifically, the water pump PWM signal passes through the voltage division of the first resistor R1 and the fourth resistor R4, and then passes through the first diode D1. The first diode D1 has unidirectional conductivity. If the voltage division of the first resistor R1 and the fourth resistor R4 is greater than the input voltage VCC, the voltage of the input voltage VCC will be limited;

[0027] The voltage after limiting passes through the first Schmitt inverter U1C, which will output a low level when the input voltage is greater than a certain value, and will output a high level when the input voltage is lower than a certain value; the water pump PWM signal passes through the first Schmitt inverter U1C and the second Schmitt inverter U1D for secondary waveform rectification, and then is filtered by the RC filter circuit to input the precise water pump PWM signal into the microcontroller.

[0028] It should be noted that this solution only provides a circuit structure for transmitting the water pump PWM signal to the microcontroller. It does not provide a detailed description of how the microcontroller parses and calculates after receiving the PWM signal and judges whether the current device is operating normally based on this. The parsing and calculation of the PWM signal can be carried out using conventional technical solutions disclosed in the art.

[0029] A second capacitor C2 is further connected to the same end of the first diode D1 and the second resistor R2 , and the other end of the second capacitor C2 is grounded for filtering the input signal.

[0030] The model of the first diode D1 is 1N4007; the model of the second capacitor C2 is 10pf / 50V.

[0031] In this embodiment, the RC filter circuit includes a third resistor R3 and a third capacitor C3 connected to each other. One end of the third resistor R3 is connected to the level output end of the second Schmitt inverter U1D, and the other end is connected to the microcontroller. The other end of the third capacitor is grounded.

[0032] The model of the third resistor R3 is 100R / 1%, and the model of the third capacitor C3 is 100pf / 50V.

[0033] As the optimization of each electronic component in this solution:

[0034] The model of the first resistor R1 is 4.7K / 1%;

[0035] The model of the second resistor R2 is 100K / 1%;

[0036] The model of the fourth resistor R4 is 10K / 1%;

[0037] The model of the first capacitor C1 is 4.7nF / 100V;

[0038] The first Schmitt inverter U1C and the second Schmitt inverter U1D both use SN74HC14 Schmitt inverters.

[0039] The above description is only for explaining the implementation mode of the present invention and is not intended to limit the present invention. For those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A PWM detection circuit, characterized in that: The invention comprises a current limiting and voltage dividing circuit, a voltage limiting circuit, a secondary isolation shaping circuit, an RC filtering circuit and a microcontroller connected in sequence, wherein the current limiting and voltage dividing circuit comprises a first resistor (R1) and a fourth resistor (R4) connected to each other and connected in parallel with a first capacitor (C1); the voltage limiting circuit comprises a first diode (D1) and a second resistor (R2) connected to each other, wherein the cathode of the first diode (D1) is connected to the first resistor (R1) and the fourth resistor (R4), the anode of the first diode (D1) is connected to the second resistor (R2), and the other end of the second resistor is connected to an input voltage (VCC); The secondary isolation shaping circuit includes a first Schmitt inverter (U1C) and a second Schmitt inverter (U1D) connected to each other, the level input end of the first Schmitt inverter (U1C) is connected to the voltage limiting circuit, the level output end of the first Schmitt inverter (U1C) is connected to the level input end of the second Schmitt inverter (U1D), and the level output end of the second Schmitt inverter (U1D) is connected to the RC filter circuit.

2. A PWM detection circuit according to claim 1, characterized in that: The same end of the first diode (D1) and the second resistor (R2) is also connected to a second capacitor (C2).

3. A PWM detection circuit according to claim 2, characterized in that: The model of the second capacitor (C2) is 10pf / 50V.

4. A PWM detection circuit according to claim 1, characterized in that: The RC filter circuit comprises a third resistor (R3) and a third capacitor (C3) connected to each other, one end of the third resistor (R3) is connected to the level output end of the second Schmitt inverter (U1D), and the other end is connected to the microcontroller.

5. A PWM detection circuit according to claim 4, characterized in that: The model of the third resistor (R3) is 100R / 1%, and the model of the third capacitor (C3) is 100pf / 50V.

6. A PWM detection circuit according to claim 1, characterized in that: The model of the first resistor (R1) is 4.7K / 1%.

7. A PWM detection circuit according to claim 1, characterized in that: The model of the second resistor (R2) is 100K / 1%.

8. The PWM detection circuit according to claim 1, characterized in that: The model of the fourth resistor (R4) is 10K / 1%.

9. The PWM detection circuit according to claim 1, characterized in that: The model of the first capacitor (C1) is 4.7nF / 100V‌.

10. The PWM detection circuit according to claim 1, characterized in that: The first Schmitt inverter (U1C) and the second Schmitt inverter (U1D) both use SN74HC14 Schmitt inverters.

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