A circuit structure and method for expanding a control chip DA port into a PWM port

Abstract

This application discloses a circuit structure and method for expanding a control chip's DA port into a PWM port. The circuit structure includes a main control chip having a DA port and a GPIO port. The analog output of the DA port is connected to a signal proportional amplifier circuit unit, the analog output of which is connected to a PWM generation circuit unit, and the control output of the GPIO port is connected to the EN port of the PWM generation circuit unit. The main control chip outputs an analog quantity x through the DA port. This analog quantity x is converted into an analog signal y by the signal proportional amplifier circuit. The PWM generation circuit converts the received analog signal y into a target controllable PWM duty cycle signal z, thereby achieving the effect of expanding the PWM port.

Description

Technical Field

[0001] The present application relates to a circuit structure and method for expanding a DA port of a control chip into a PWM port, which is applied to technical occasions such as photovoltaic inverters, motor drivers, and UPS that require the use of a control chip (DSP / ARM / MCU) for PWM duty cycle control, and relates to the field of PWM control technology. Background Art

[0002] Currently, power electronic devices such as photovoltaic inverters, motor drives, and UPS systems all require control chips such as DSPs, ARM processors, or MCUs. These chips must also have PWM ports for duty cycle control. However, the number of PWM ports on a given chip is often limited. In many applications, when the number of PWM ports built into the control chip is insufficient to meet control requirements, it's necessary to select a control chip with more PWM ports or use other methods to increase the number of PWM ports. Currently, there are several methods for expanding PWM ports without replacing the control chip.

[0003] Method 1: Add CPLD / FPGA expansion to the existing main control chip, and the CPLD / FPGA expansion provides additional PWM ports, such as Figure 1 Method 2: Add an auxiliary slave control chip to the existing master control chip, and the slave control chip provides additional PWM ports, such as Figure 2 Method 3: Add a dedicated PWM port expansion chip to the existing main control chip, and the dedicated PWM expansion chip provides additional PWM ports, such as Figure 3 ;

[0004] While the above three expansion methods achieve the goal of expanding PWM ports without replacing the master control chip, they also have some drawbacks. While methods 1 and 2 don't require replacing the master control chip, they do add slave control chips or CPLDs or FPGAs, significantly increasing costs and requiring programming of the expansion components, making ongoing maintenance more complex. Method 3 utilizes a dedicated PWM expansion chip, which is relatively simple to program and maintain, and is reasonably priced. However, dedicated PWM expansion chips are typically used in low-switching frequency applications, such as LED control, and are not suitable for higher-switching frequency applications. Summary of the Invention

[0005] The technical problem to be solved by this application is the insufficient number of PWM ports of the main control chip.

[0006] In order to solve the above technical problems, the technical solution of the present application is to provide a circuit structure in which the DA port of a control chip is expanded into a PWM port, including a main control chip having a DA port and a GPIO port, the analog output of the DA port is connected to a signal proportional amplification circuit unit, the analog output of the signal proportional amplification circuit unit is connected to a PWM generation circuit unit, and the control output of the GPIO port is connected to the EN port of the PWM generation circuit unit.

[0007] Preferably, the signal proportional amplification circuit unit is configured as a non-inverting amplification circuit, an inverting amplification circuit, an addition circuit, a subtraction circuit, or a conversion circuit with an integrated operational amplifier as its core. Specifically, a non-inverting proportional amplification circuit composed of a first-stage voltage follower and a first-stage addition circuit is used.

[0008] Preferably, the PWM generation circuit unit is configured as a PWM generation circuit based on an SG3525, UC2844 or LM5022 integrated circuit chip or a triangle wave comparison PWM generation circuit constructed by an independent device. Specifically, a PWM generation circuit based on an SG3525 integrated circuit chip is used.

[0009] Preferably, the main control chip is a DSP, ARM or MCU main control chip.

[0010] Preferably, the DA port of the main control chip is a port provided by the main control chip or a DA port obtained by the main control chip through external expansion.

[0011] Based on the above circuit structure, the present application also provides a method for expanding the DA port of a control chip into a PWM port, which is characterized in that the main control chip controls the output of an analog quantity x through the DA port, and the analog quantity x is converted into an analog signal y through a signal proportional amplification circuit, and the PWM generation circuit converts the received analog signal y into a target controllable PWM duty cycle signal z. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of adding a CPLD / FPGA extension to an existing main control chip in the prior art, wherein the CPLD / FPGA extension provides an additional PWM port;

[0013] Figure 2 A schematic diagram of adding an auxiliary slave control chip to an existing master control chip in the prior art, wherein the slave control chip provides an additional PWM port;

[0014] Figure 3 A schematic diagram of adding a dedicated PWM port expansion chip to an existing main control chip in the prior art, wherein the dedicated PWM expansion chip provides an additional PWM port;

[0015] Figure 4 Schematic diagram of the expansion circuit for expanding the idle DA port of the main control chip into a PWM port;

[0016] Figure 5 This is a schematic diagram of the main control chip obtaining the DA port through external expansion;

[0017] Figure 6 This is a schematic diagram of how the main control chip uses the PWM port to convert the DA port through the filter circuit;

[0018] Figure 7 Schematic diagram of the implementation circuit of the signal proportional amplification circuit unit;

[0019] Figure 8 Schematic diagram of the SG3525 chip used in the PWM generation circuit unit. DETAILED DESCRIPTION

[0020] In order to make the present application more clear and easy to understand, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0021] The present application provides a method for expanding the idle DA port of the main control chip into a PWM port, which is achieved by expanding the circuit structure, such as Figure 4 As shown, the expansion circuit includes a main control chip 1 with an idle DA port and an idle GPIO port, and a signal proportional amplification circuit unit 2 and a PWM generation circuit unit 3 connected to the main control chip 1 in sequence; the signal proportional amplification circuit unit 2 is a signal conditioning circuit composed of an operational amplifier, etc. The output end of the DA port of the main control chip 1 is connected to the input end of the signal proportional amplification circuit unit 2, and the output end of the signal proportional amplification circuit unit 2 is connected to the input end of the PWM generation circuit unit 3. The PWM generation circuit unit 3 performs PWM conversion output through internal carrier comparison, and the GPIO port of the main control chip 1 is connected to the EN port of the PWM generation circuit unit 3. The main control chip 1. The general GPIO port controls the turning on or off of the working state of the PWM generation circuit unit 3. Among them, the signal proportional amplification circuit unit 2 can be a conversion circuit with an integrated operational amplifier as the core, such as a non-inverting amplifier circuit, an inverting amplifier circuit, an adding circuit, a subtracting circuit, etc.; the PWM generation circuit unit 3 can be a PWM generation circuit based on the SG3525 integrated circuit chip. Of course, the circuit core is not limited to the SG3525 integrated circuit chip, and can also be other PWM integrated circuits, such as UC2844, LM5022, etc., which have similar functions. It can also be a triangle wave comparison PWM generation circuit built by independent devices.

[0022] Specifically, the idle DA port on the main control chip 1 is used to generate analog quantities. The DA port can be a port provided by the main control chip 1 or a DA port obtained by the main control chip 1 through external expansion, such as Figure 5 As shown, the main control chip 1 for external expansion to obtain a DA port includes a main control chip body 1-1 and a DA expansion module 1-2 connected to the main control chip body 1-1. The DA expansion module 1-2 has a dedicated DA integrated circuit inside. The main control chip body 1-1 communicates with the dedicated DA integrated circuit of the DA expansion module 1-2 via an SPI / I2C / SCI / parallel port communication port to expand the DA output analog. The analog quantity is converted into a PWM signal output through a signal proportional amplification circuit unit 2 and a PWM generation circuit unit 3. In addition, the main control chip 1 can also use the DA port converted by the main chip PWM port through a filter circuit, such as Figure 6 As shown, the main control chip 1 is composed of a main control chip body 1a and a signal filtering unit 1b. The idle PWM port of the main control chip body 1a produces a duty cycle signal representing an analog quantity, and the signal filtering unit 1b converts the PWM duty cycle signal representing the analog quantity into an analog signal through filtering.

[0023] This application utilizes an unused DA port on a main control chip to expand it into a PWM port. The key technical point is that the main control chip 1 outputs an analog quantity x through the DA port. This analog quantity x passes through a signal proportional amplification circuit unit 2 and is converted into an analog signal y that can be received by a PWM generation circuit unit 3. The PWM generation circuit unit 3 then converts the received analog signal y into a target controllable PWM duty cycle signal z. This application provides a signal propagation path for this process, as well as a method for expanding the main control chip's PWM port through this signal path.

[0024] Specifically, the PWM generation circuit unit 3 may be a PWM generation circuit based on the SG3525 integrated circuit. The following describes a specific implementation using the SG3525 as the core:

[0025] In multi-channel MPPT string photovoltaic inverters or energy storage inverters, limited PWM ports are used for inverter algorithm control. Boost or buck algorithm control can use the technical solution provided in this application to generate PWM control. This saves PWM ports on the main control chip and reduces circuit costs.

[0026] Main control chip 1: When using TI's DSP in a photovoltaic inverter, its DA port is often idle. This DA port can output the control voltage signal of the photovoltaic MPPT algorithm.

[0027] Signal proportional amplifier circuit unit 2: It is composed of a voltage follower and an adder circuit. This circuit converts the control voltage signal of the MPPT algorithm into a PWM generation circuit unit 3 that can receive analog signals, such as Figure 7 shown.

[0028] PWM generation circuit unit 3: This embodiment uses the SG3525 chip as the core, such as Figure 8 As shown in the figure, U1's pin 6 is connected to the power ground via R5, and U1's pin 5 is connected to the power ground via C2. Adjusting the values ​​of R5 and C2 can set the PWM carrier frequency. U1's pin 7 is connected to U1's pin 5 via R7, and adjusting R7's value can set the PWMA and PWMB dead time. U1's pin 1 is connected to pin 9 via resistor R2, and then to the analog output signal of unit 2. Changing the input signal Vin changes the duty cycle of the output PWM. U1's pin 10 is connected to the GPIO port of unit 1 via a switching circuit formed by MOS transistor Q1, resistors R1, R4, and R6. The main control chip 1 uses the GPIO to control the operating state of the PWM generation circuit unit 3.

Claims

1. A circuit structure for expanding a DA port of a control chip into a PWM port, characterized in that: The invention comprises a main control chip with an idle DA port and an idle GPIO port, wherein the idle DA port of the main control chip is expanded into a PWM port, the analog output of the idle DA port is connected to a signal proportional amplification circuit unit, the analog quantity is obtained by filtering and converting a PWM duty cycle signal representing the analog quantity, the analog output of the signal proportional amplification circuit unit is connected to a PWM generation circuit unit, the PWM generation circuit unit performs PWM conversion output through internal carrier comparison, and the control output of the idle GPIO port is connected to the EN port of the PWM generation circuit unit.

2. The circuit structure of expanding a DA port of a control chip into a PWM port according to claim 1, characterized in that: The signal proportional amplification circuit unit is configured as a non-inverting amplification circuit, an inverting amplification circuit, an addition circuit, a subtraction circuit, or a conversion circuit with an integrated operational amplifier as its core.

3. The circuit structure of expanding a DA port of a control chip into a PWM port according to claim 2, characterized in that: The signal proportional amplification circuit unit is configured as a non-inverting proportional amplification circuit consisting of a first-stage voltage follower and a first-stage adding circuit.

4. The circuit structure of expanding a DA port of a control chip into a PWM port according to claim 1, characterized in that: The PWM generation circuit unit is configured as a PWM generation circuit based on an SG3525, UC2844 or LM5022 integrated circuit chip or a triangle wave comparison PWM generation circuit constructed by an independent device.

5. The circuit structure for expanding a DA port of a control chip into a PWM port as claimed in claim 4, characterized in that: The PWM generation circuit unit is configured as a PWM generation circuit based on an SG3525 integrated circuit chip.

6. The circuit structure for expanding a DA port of a control chip into a PWM port according to claim 1, characterized in that: The main control chip is a DSP, ARM or MCU main control chip.

7. The circuit structure for expanding a DA port of a control chip into a PWM port according to claim 6, characterized in that: The idle DA port of the main control chip is a port provided by the main control chip or an idle DA port obtained by the main control chip through external expansion.

8. A method for expanding a DA port of a control chip to a PWM port, characterized in that: Based on the circuit structure of claim 1, the method comprises the following steps: The control quantity of the main control chip outputs the analog quantity x through the idle DA port. The analog quantity x is converted into the analog signal y through the signal proportional amplification circuit. The PWM generation circuit converts the received analog signal y into a target controllable PWM duty cycle signal.

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