A voltage control circuit

Abstract

This invention discloses a voltage control circuit applied to a charging system, comprising an adjustment feedback circuit, an output feedback circuit, a comparator circuit, and a digital control circuit. The adjustment feedback circuit is connected to the output terminal of a DC-DC circuit in the charging system and is also connected to the digital control circuit to adjust the output voltage of the DC-DC circuit according to a control signal from the digital control circuit. The output feedback circuit is connected to the output terminals of both the DC-DC circuit and the adjustment feedback circuit to detect the output voltage of the DC-DC circuit. The input terminal of the comparator circuit is connected to the digital control circuit and the adjustment feedback circuit / output feedback circuit, and its output terminal is connected to the digital control circuit to output an adjustment signal based on the voltage from the adjustment feedback circuit / output feedback circuit and the digital control circuit. The digital control circuit is connected to the comparator circuit and the adjustment feedback circuit to output a control signal based on the adjustment signal, thereby achieving closed-loop voltage control.

Description

Technical Field

[0001] This invention relates to a voltage control circuit. Background Technology

[0002] With the development of microelectronics and renewable energy technologies, fast charging technology has achieved rapid progress, market demand is constantly increasing, and high voltage and high current are being widely used. In charging systems, in order to achieve precise power output and speed control, the output voltage needs to be precisely adjusted, and load information needs to be provided to the charging controller to achieve high-precision closed-loop control.

[0003] Currently, charging control generally employs a software-controlled closed-loop system. The charging head outputs a set voltage to the system being charged, which then controls its output power and simultaneously instructs the charging head to adjust its output voltage to achieve the desired output power. In this closed-loop system control, a current-type DAC is typically used to precisely regulate the DC power supply voltage. Furthermore, the need for complex communication protocols between the charger and the device being charged to ensure accurate and timely real-time communication increases the design complexity and cost of fast charging. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a voltage control circuit with adjustable output voltage, simple structure and low cost.

[0005] To solve the above-mentioned technical problems, the present invention provides a voltage control circuit for use in a charging system, comprising an adjustment feedback circuit, an output feedback circuit, a comparison circuit, and a digital control circuit, wherein...

[0006] The adjustment feedback circuit is connected to the output terminal of the DC-DC circuit in the charging system and is connected to the digital control circuit to adjust the output voltage of the DC-DC circuit according to the control signal from the digital control circuit.

[0007] The output feedback circuit is connected to the output terminals of the DC-DC circuit and the regulation feedback circuit, and is used to detect the output voltage of the DC-DC circuit.

[0008] The input terminal of the comparator circuit is connected to the digital control circuit and the adjustment feedback circuit / output feedback circuit, and its output terminal is connected to the digital control circuit to output an adjustment signal based on the voltage from the adjustment feedback circuit / output feedback circuit and the digital control circuit.

[0009] The digital control circuit, the comparison circuit, and the adjustment feedback circuit are connected to output two corresponding PWM control signals according to the adjustment signal, so as to realize voltage closed-loop control.

[0010] The further technical solution is as follows: the adjustment feedback circuit includes a first resistor, a second resistor, a fifth resistor and a third switch. One end of the fifth resistor is connected to the output terminal of the DC-DC circuit, and the other end is connected to one end of the first resistor and the second resistor. The other end of the second resistor is connected to the comparator circuit and the third switch. The other end of the third switch is connected to the digital control circuit, and the other end of the first resistor is grounded.

[0011] The further technical solution is as follows: the output feedback circuit includes a third resistor and a fourth resistor. One end of the third resistor is connected to the output terminal of the DC-DC circuit and the adjustment feedback circuit, and the other end is connected to the fourth resistor and the comparison circuit. The other end of the fourth resistor is grounded.

[0012] The further technical solution is as follows: the comparison circuit includes a comparator, a first switch and a second switch. The non-inverting input terminal and the inverting input terminal of the comparator are respectively connected to the common terminal of the first switch and the second switch. Its output terminal is connected to the digital control circuit. The normally closed terminal and the normally open terminal of the first switch are respectively connected to the adjustment feedback circuit and the output feedback circuit. The normally closed terminal and the normally open terminal of the second switch are respectively connected to the two PWM control signals of the digital control circuit.

[0013] The further technical solution is as follows: the voltage control circuit further includes two RC filter circuits, the input terminal of each RC filter circuit is connected to an output pin of the digital control circuit, and the output terminal of one of the RC filter circuits is connected to the normally closed terminal of the second switch and the adjustment feedback circuit, and the output terminal of the other RC filter circuit is connected to the normally open terminal of the second switch.

[0014] The further technical solution is as follows: the RC filter circuit includes a first filter resistor, a second filter resistor, a first filter capacitor, and a second filter capacitor. One end of the first filter resistor serves as the input terminal of the RC filter circuit, and its other end is connected to the first filter capacitor and the second filter resistor. The other end of the second filter resistor is connected to the second filter capacitor and serves as the output terminal of the RC filter circuit. The other ends of the first filter capacitor and the second filter capacitor are both grounded.

[0015] The further technical solution is as follows: the digital control circuit includes two PWM generators and a DSP main control circuit. One of the two PWM generators is connected to the normally closed terminal of the second switch and the adjustment feedback circuit, and the other PWM generator is connected to the normally open terminal of the second switch. The DSP main control circuit is connected to the output terminal of the comparator so as to cause the two PWM generators to work according to the adjustment signal from the comparator circuit and generate corresponding PWM control signals.

[0016] A further technical solution is as follows: the voltage control circuit further includes a sampling resistor, which is connected between the output terminal of the DC-DC circuit and the output feedback circuit.

[0017] Compared with existing technologies, the voltage control circuit of this invention can adjust the output voltage of the DC-DC circuit in the charging system by adjusting the feedback circuit. The output feedback circuit can detect the output voltage and compare it with the set control signal voltage through the comparison circuit, thereby outputting an adjustment signal to the digital control circuit. This allows for closed-loop correction of the output voltage of the DC / DC circuit through the adjustment feedback circuit. Therefore, the voltage control circuit of this invention uses a hybrid digital and analog circuit approach to precisely control the output voltage. It sets the voltage through digital PWM control, replacing the more expensive current-type DAC. This enables precise control of the output voltage, reducing its size and complexity. The circuit is simple in structure, low in cost, and adaptable to load changes, quickly locking the output. When the load changes, the comparison circuit can quickly detect the change, allowing for precise real-time compensation without relying on load measurement and feedback from the charged device. This reduces loop response time, lowers the requirements on the charged device, and ensures the stability and accuracy of the charging system. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the circuit structure of a specific embodiment of the voltage control circuit of the present invention.

[0019] Figure 2 This is a schematic diagram of the specific structure of the RC filter circuit in the voltage control circuit of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to more clearly understand the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] Reference Figure 1 , Figure 1This is a schematic diagram of the circuit structure of a specific embodiment of the voltage control circuit of the present invention. The voltage control circuit of the present invention is applied to a charging system. In the embodiment shown in the figure, the voltage control circuit includes an adjustment feedback circuit 11, an output feedback circuit 12, a comparator circuit 13, and a digital control circuit 14. The adjustment feedback circuit 11 is connected to the output terminal of the DC-DC circuit 20 in the charging system and is also connected to the digital control circuit 14 to adjust the output voltage of the DC-DC circuit 20 according to the control signal from the digital control circuit 14. The output feedback circuit 12 is connected to the output terminals of the DC-DC circuit 20 and the adjustment feedback circuit 11, and is used to detect the output voltage of the DC-DC circuit 20. The input terminal of the comparator circuit 13 is connected to the digital control circuit 14 and the adjustment feedback circuit 11 / output feedback circuit 12, and its output terminal is connected to the digital control circuit 14 to output an adjustment signal according to the voltage from the adjustment feedback circuit 11 / output feedback circuit 12 and the digital control circuit 14. The digital control circuit 14, the comparator circuit 13, and the adjustment feedback circuit 11 are connected to output two corresponding PWM control signals according to the adjustment signal to achieve closed-loop voltage control.

[0022] In some embodiments, the adjustment feedback circuit 11 includes a first resistor R1, a second resistor R2, a fifth resistor R0, and a third switch SW3. One end of the fifth resistor R0 is connected to the output terminal of the DC-DC circuit 20, and the other end is connected to one end of the first resistor R1 and the second resistor R2. The other end of the second resistor R2 is connected to the comparator circuit 13 and the third switch SW3. The other end of the third switch SW3 is connected to the digital control circuit 14 and the comparator circuit 13. The other end of the first resistor R1 is grounded.

[0023] In some embodiments, the output feedback circuit 12 includes a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 is connected to the output terminal of the DC-DC circuit 20 and the adjustment feedback circuit 11, and the other end is connected to the fourth resistor R4 and the comparator circuit 13. The other end of the fourth resistor R4 is grounded. Preferably, the voltage control circuit further includes a resistor RL, one end of which is connected to the end of the third resistor R3 connected to the output terminal of the DC-DC circuit 20, and the other end is grounded.

[0024] In this embodiment, the comparison circuit 13 includes a comparator U1, a first switch SW1, and a second switch SW2. The non-inverting input and the inverting input of the comparator U1 are respectively connected to the common terminal of the first switch SW1 and the second switch SW2, and its output is connected to the digital control circuit. The normally closed terminal of the first switch SW1 is connected to the second resistor R2 and the third switch SW3 in the adjustment feedback circuit 11. The normally open terminal of the first switch SW1 is connected to the output feedback circuit 12. The normally closed terminal and the normally open terminal of the second switch SW2 are respectively connected to the two PWM control signals of the digital control circuit 14.

[0025] In some embodiments, the digital control circuit 14 includes two PWM generators and a DSP main control circuit 143. Specifically, it includes two PWM generators, PWM1141 and PWM2142. PWM1141 is connected to the normally closed terminal of the second switch SW2 and the third switch SW3, and PWM2142 is connected to the normally open terminal of the second switch SW2. The DSP main control circuit 143 is connected to the output terminal of the comparator circuit 13 to cause the two PWM generators to work according to the adjustment signal from the comparator circuit 13, generating corresponding PWM control signals. When the voltage control circuit is in operation, the non-inverting input terminal of the comparator U1 is connected to the output feedback circuit 12 through the first switch SW1, and its inverting input terminal is connected to PWM2142 through the second switch SW2. By comparing the output voltage with the set control signal voltage, an adjustment signal is output to the DSP main control circuit 143, thereby performing closed-loop correction of the output voltage of the DC / DC circuit 20 through PWM1141 and the adjustment feedback circuit 11. Preferably, in this embodiment, it may also include a setting register group, a digital main chip 144, and a communication module (PD / I2C / UART) 145.

[0026] Furthermore, the voltage control circuit also includes two RC filter circuits. The input terminal of each RC filter circuit is connected to an output pin of the digital control circuit 14, and the output terminal of one RC filter circuit RC1 is connected to the normally closed terminal of the second switch SW2 and the adjustment feedback circuit 11, while the output terminal of the other RC filter circuit RC2 is connected to the normally open terminal of the second switch SW2.

[0027] Specifically, such as Figure 2 As shown, the RC filter circuit includes a first filter resistor R11, a second filter resistor R12, a first filter capacitor C11, and a second filter capacitor C12. One end of the first filter resistor R11 serves as the input terminal INPUT of the RC filter circuit, and its other end is connected to the first filter capacitor C11 and the second filter resistor R12. The other end of the second filter resistor R12 is connected to the second filter capacitor C12 and serves as the output terminal OUTPUT of the RC filter circuit. The other ends of the first filter capacitor C11 and the second filter capacitor C12 are both grounded.

[0028] In some embodiments, the voltage control circuit further includes a sampling resistor Rc, which is connected between the output terminal of the DC-DC circuit 20 and the output feedback circuit 12. Based on the above design, the load current can be monitored in real time through the sampling resistor Rc. When the load current is zero, the voltage across the sampling resistor Rc is zero.

[0029] Understandably, in the initial stage, the voltage control circuit of the present invention is in an automatic calibration stage. The common terminal of the first switch SW1 and the second switch SW2 are both connected to their normally closed terminals, the third switch SW3 is in the open state, the two networks PWM1141 and RC1 are scanned, the comparator circuit 13 compares the initial set voltage output by the adjustment feedback circuit 11 and PWM1141 to detect the balance point of the voltage across the second resistor R2, and then sends the balance point to the DSP main control circuit 143, and the calibration ends. In the working stage, the common terminal of the first switch SW1 and the second switch SW2 are both connected to their normally open terminals, the third switch SW3 is in the closed state, the initial set Duty0 of PWM1141 (the duty cycle corresponding to PWM1141 at the beginning) is set according to the balance point, the initial set of PWM2142 is determined by the output feedback circuit 12, the comparator circuit 13 compares the voltage fed back by the output feedback circuit 12 with the voltage set by PWM2142, and thus outputs the adjustment signal to the DSP main control circuit 143.

[0030] Since the output voltage VDD1 of the DC-DC circuit 20 = V0 + Verf * (Duty0 - Dutyset) * R0 / R2, where V0 is the initial output voltage of the DC-DC circuit 20, Verf is the drive voltage, Duty0 is the duty cycle corresponding to PWM1141 initially, and Dutyset is the duty cycle value set by PWM1141 corresponding to the output VDD1, it can be seen that when Dutyset > Duty0, VDD1 decreases relative to the initial voltage V0, and when Dutyset < Duty0, VDD1 increases relative to the initial voltage V0. Then, when the load changes, by comparing the voltage generated by PWM2142 with the voltage fed back by the output feedback circuit 12, the comparison result is input into the DSP main control circuit 143 for filtering and algorithm processing, and the output of PWM1141 is changed, thereby adjusting VDD1 to achieve the accurate set load voltage VDD2. For example, when the voltage fed back by the output feedback circuit 12 is less than the voltage set by PWM2142, the load is relatively heavy at this time. By reducing the set value Dutyset of PWM1141, the output voltage of VDD1 can be increased to achieve the purpose of maintaining VDD2 unchanged; similarly, when the voltage fed back by the output feedback circuit 12 is greater than the voltage set by PWM2142, the load is relatively light at this time. By increasing the set value Dutyset of PWM1141, the output voltage of VDD1 can be reduced to achieve the purpose of maintaining VDD2 unchanged. That is, the Dutyset of PWM1141 will self-adjust according to the change of the load to ensure that the load voltage VDD2 is the set voltage. That is, the voltage control circuit of the present invention can automatically correct the output voltage of the DC / DC circuit in the early stage and automatically adjust the load fluctuation in the later stage to ensure the stability and accuracy of the charging system.

[0031] In summary, the voltage control circuit of this invention can adjust the output voltage of the DC-DC circuit in the charging system by adjusting the feedback circuit. The output feedback circuit can detect the output voltage and compare it with the set control signal voltage through the comparison circuit, thereby outputting an adjustment signal to the digital control circuit. This allows for closed-loop correction of the output voltage of the DC / DC circuit through the adjustment feedback circuit. It can be seen that the voltage control circuit of this invention uses a hybrid digital and analog circuit approach to precisely control the output voltage. It sets the voltage using digital PWM control, replacing the more expensive current-type DAC. This enables precise control of the output voltage, allowing for both large and small adjustments. The structure is relatively simple and low-cost, requiring only a comparator, two RC filter circuits, and some resistors. Combined with the digital control circuit, it solves the problems of slow loop load response and poor output accuracy, improving the reliability and accuracy of the set voltage. It also improves the control response speed and can adapt to load changes, quickly locking the output. When the load changes, the comparison circuit can quickly detect the change, allowing for precise real-time compensation without needing to adjust based on load measurement feedback from the charged device. This reduces loop response time, lowers the requirements on the charged device, and ensures the stability and accuracy of the charging system.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Those skilled in the art can make various equivalent changes and improvements based on the above embodiments, and all equivalent variations or modifications made within the scope of the claims should fall within the protection scope of the present invention.

Claims

1. A voltage control circuit applied to a charging system, characterized in that: It includes an adjustment feedback circuit, an output feedback circuit, a comparator circuit, and a digital control circuit, among which, The adjustment feedback circuit is connected to the output terminal of the DC-DC circuit in the charging system and is connected to the digital control circuit to adjust the output voltage of the DC-DC circuit according to the control signal from the digital control circuit. It includes a first resistor, a second resistor, a fifth resistor and a third switch. One end of the fifth resistor is connected to the output terminal of the DC-DC circuit, and the other end is connected to one end of the first resistor and the second resistor. The other end of the second resistor is connected to the comparator circuit and the third switch. The other end of the third switch is connected to the digital control circuit, and the other end of the first resistor is grounded. The output feedback circuit is connected to the output terminals of the DC-DC circuit and the regulation feedback circuit, and is used to detect the output voltage of the DC-DC circuit. It includes a third resistor and a fourth resistor. One end of the third resistor is connected to the output terminals of the DC-DC circuit and the regulation feedback circuit, and the other end is connected to the fourth resistor and the comparison circuit. The other end of the fourth resistor is grounded. The input terminal of the comparator circuit is connected to the digital control circuit and the adjustment feedback circuit / output feedback circuit, and its output terminal is connected to the digital control circuit to output an adjustment signal according to the voltage from the adjustment feedback circuit / output feedback circuit and the digital control circuit. The comparator includes a comparator, a first switch and a second switch. The non-inverting input terminal and the inverting input terminal of the comparator are respectively connected to the common terminal of the first switch and the second switch, and its output terminal is connected to the digital control circuit. The normally closed terminal and the normally open terminal of the first switch are respectively connected to the adjustment feedback circuit and the output feedback circuit, and the normally closed terminal and the normally open terminal of the second switch are respectively connected to two PWM control signals of the digital control circuit. The digital control circuit, the comparison circuit, and the adjustment feedback circuit are connected to output two corresponding PWM control signals according to the adjustment signal, so as to realize voltage closed-loop control.

2. The voltage control circuit of claim 1, wherein: The voltage control circuit further includes two RC filter circuits. The input terminal of each RC filter circuit is connected to an output pin of the digital control circuit, and the output terminal of one RC filter circuit is connected to the normally closed terminal of the second switch and the adjustment feedback circuit, while the output terminal of the other RC filter circuit is connected to the normally open terminal of the second switch.

3. The voltage control circuit of claim 2, wherein: The RC filter circuit includes a first filter resistor, a second filter resistor, a first filter capacitor, and a second filter capacitor. One end of the first filter resistor serves as the input terminal of the RC filter circuit, and the other end is connected to the first filter capacitor and the second filter resistor. The other end of the second filter resistor is connected to the second filter capacitor and serves as the output terminal of the RC filter circuit. The other ends of both the first filter capacitor and the second filter capacitor are grounded.

4. The voltage control circuit of claim 1, wherein: The digital control circuit includes two PWM generators and a DSP main control circuit. One of the PWM generators is connected to the normally closed terminal of the second switch and the adjustment feedback circuit, and the other PWM generator is connected to the normally open terminal of the second switch. The DSP main control circuit is connected to the output terminal of the comparator to enable the two PWM generators to work according to the adjustment signal from the comparator circuit and generate corresponding PWM control signals.

5. The voltage control circuit of claim 1, wherein: The voltage control circuit further comprises a sampling resistor connected between the output of the DC-DC circuit and an output feedback circuit.

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