Negative logic UC3901 isolation control circuit and method based on phase-shifted full-bridge converter

Abstract

The invention provides a negative logic UC3901 isolation control circuit and method based on a phase-shifted full-bridge converter. The circuit is characterized by comprising a full-bridge inverter, a power transformer, a current doubler rectifier, a voltage and current sampling circuit, a voltage loop compensation network, a current loop compensation network, a magnetic isolation circuit, a main control circuit and a driving circuit, the full-bridge inverter, the power transformer and the current doubler rectifier form a power circuit of the converter, and the rest parts form a control circuit; the magnetic isolation circuit comprises a UC3901 chopping chip, an isolation transformer and a rectifier filter, and the UC3901 chip is used for chopping an analog control signal Vcoms of over 0.45 V, so that the analog control signal Vcoms becomes an alternating current signal, and magnetic isolation transmission of the analog signal is realized. A conventional magnetic isolation drive circuit is replaced by the magnetic isolation circuit, the size and the weight of the circuit are reduced, and meanwhile a novel magnetic isolation mode is provided.

Description

Technical Field

[0001] This invention belongs to the field of power management technology for satellite power systems, and relates to a negative logic UC3901 isolation control circuit and method based on a phase-shifting full-bridge converter. Background Technology

[0002] As a core component of a satellite, the power system's main task is to provide high-quality, highly reliable continuous power to the entire satellite, meeting the power requirements of the entire satellite's power load.

[0003] With the continuous development of aerospace technology, the requirements for space power systems are becoming increasingly stringent. Satellite payloads require power system converters to have good anti-interference capabilities and security, therefore isolated topologies are typically selected.

[0004] The converter's control strategy employs a dual closed-loop control of output voltage and current. Since the primary and secondary sides of the converter are not grounded, and to reduce the converter's size, the primary-side main switch is driven by an IR2110 chip. Therefore, control signal isolation is required. Common isolation methods include magnetic isolation and optocoupler isolation. To meet the reliability requirements of aerospace power systems, magnetic isolation is chosen. However, a mature magnetic isolation circuit solution is not yet available in this field. Summary of the Invention

[0005] To overcome this deficiency, this invention provides a negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter. Its features include a full-bridge inverter, a power transformer, a current doubler rectifier, a voltage and current sampling circuit, a voltage loop compensation network, a current loop compensation network, a magnetic isolation circuit, a main control circuit, and a drive circuit. The full-bridge inverter, power transformer, and current doubler rectifier constitute the power circuit of the converter, while the remaining components constitute the control circuit. The magnetic isolation circuit includes a UC3901 chopper chip, an isolation transformer, and a rectifier filter. The UC3901 chip is used to process analog control signals above 0.45V. V com_s The signal is chopped to become an AC signal, enabling magnetically isolated transmission of the analog signal.

[0006] This invention also provides a negative logic UC3901 isolation control method based on a phase-shifted full-bridge converter, characterized in that it uses the aforementioned negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter, and includes the following steps: Output voltage of the power circuit v o Samples are taken and sent to the voltage loop compensation network, along with the voltage reference. V o_ref Perform proportional-integral operation; subsequently, the voltage loop compensation network outputs a signal. io_ref It serves as the current reference for the voltage loop compensation network and also affects the output current of the power circuit. i o Sampling is performed, and a DC bias is superimposed. V D Then, it is sent to the current loop compensation network and compared with the current reference. i o_ref Perform proportional-integral operation; analog control signal output by the current loop compensation network. V com_s After isolation by a magnetic isolation circuit, the output analog signal V com_p The signal enters the main control circuit, is compared with the triangular carrier generated by the main control chip, and then outputs a drive signal to the drive circuit for amplification, and then drives the four MOSFETs in the full-bridge inverter.

[0007] The advantages of this invention are: First, this invention utilizes the UC3901 chip, transformer, and rectifier filter to achieve magnetic isolation transmission of analog signals, reducing the size and weight of the circuit, while providing a novel magnetic isolation method.

[0008] Secondly, this invention superimposes a DC bias on the current sampling signal to avoid the circuit being unable to perform closed-loop modulation when the current sampling signal is 0 under no-load conditions (the allowable modulation range is 0~12V), thus ensuring the stability of the power circuit under no-load conditions. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a phase-shifting full-bridge converter and its control loop.

[0010] Figure 2 This is a magnetically isolated circuit based on the negative logic UC3901 phase-shifted full-bridge converter. Detailed Implementation

[0011] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0012] This invention provides a negative logic UC3901 isolation control circuit and method based on a phase-shifted full-bridge converter, which realizes converter isolation control through hardware circuitry.

[0013] The negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter of this invention mainly consists of a full-bridge inverter, a power transformer, a current multiplier rectifier, a voltage and current sampling circuit, a voltage loop compensation network, a current loop compensation network, a magnetic isolation circuit, a main control circuit, and a drive circuit, as follows: Figure 1 As shown.

[0014] In a phase-shifted full-bridge converter, the full-bridge inverter, power transformer, and current multiplier rectifier constitute the power circuit of the converter, while the remaining parts constitute the control circuit.

[0015] Output voltage of the power circuit v o Samples are taken and sent to the voltage loop compensation network, along with the voltage reference. V o_ref Perform proportional-integral transformation. Then, the voltage loop compensation network outputs a signal. i o_ref As a current reference for the voltage loop compensation network, and also for the output current of the power circuit. i o Sampling is performed, and a DC bias is superimposed. V D Then, it is sent to the current loop compensation network and compared with the current reference. i o_ref Perform proportional-integral (PI) calculations. The analog control signal output from the current loop compensation network. V com_s go through Figure 2 After isolation by the magnetic isolation circuit shown, the output analog signal is... V com_p The signal enters the main control circuit, is compared with the triangular carrier generated by the main control chip, and then outputs a drive signal to the drive circuit for amplification, and then drives the four MOSFETs in the full-bridge inverter.

[0016] like Figure 2 As shown, the negative logic UC3901 magnetic isolation circuit based on the phase-shifted full-bridge converter of the present invention includes a UC3901 chip and a transformer, etc.

[0017] Analog control signals are DC and cannot be directly isolated by a transformer. This invention introduces the UC3901 chip to convert the analog control signals into, for example, frequencies of... f osc A square wave signal with a constant duty cycle of 0.5. f osc This is the frequency of the UC3901's internal oscillator, thus achieving isolation. This invention allows for programmable control of the corresponding pins of the UC3901 chip.

[0018] However, the input and output voltage amplitudes of the UC3901 chip are only positively correlated when the input signal is within the voltage range of 0~0.45V. In this case, the input signal voltage range is too small, which is detrimental to the closed-loop control of the converter. If the UC3901 chip is used to isolate the control signal in this way, the aforementioned deficiency becomes a problem that urgently needs to be solved. To address this, this invention employs a negative logic UC3901 magnetic isolation circuit. This invention selects the UC3901 to operate in the region where the input and output voltage amplitudes are negatively correlated, thus obtaining the analog control signal used as the input signal voltage. V com_s Greater than 0.45V.

[0019] Specifically, the negative logic UC3901 magnetic isolation circuit includes a UC3901 chopper chip, an isolation transformer, and a rectifier filter (including R1, C2, and D1). The UC3901 chip is used to process analog control signals. V com_s The signal is chopped to become an AC signal, enabling magnetically isolated transmission of the analog signal.

[0020] This invention avoids the region where the input and output voltage amplitudes are positively correlated only at 0-0.45V, and instead utilizes the UC3901 chopper chip in the region where the input and output voltage amplitudes are negatively correlated, operating within an input voltage range above 0.45V. To ensure closed-loop control of the converter, the voltage reference in the voltage loop compensation network needs to be... V o_ref and the output voltage of the power circuit v o The sampling signal is reversed, and V o_ref Connect to the inverting input terminal. v o Connect to the positive input terminal to achieve the effect of negative times negative equaling positive.

[0021] Therefore, since the amplitudes of the input and output signals of the UC3901 are negatively correlated, in other words, the modulation signal... V com_s The larger, V com_p The smaller the duty cycle, the higher the duty cycle. D ( D The smaller the ratio of the simultaneous conduction time of the diagonal switches on the primary side to the switching cycle, the better. To ensure Δ... V o (Δ) V o = V o_ref - v o , V o_ref It serves as the voltage reference for the output voltage in the voltage loop compensation network.v o (the output voltage of the power circuit) and D If they are positively correlated, then Δ is required. V o and V com_s It exhibits a negative correlation, as previously described, the present invention by... v o Connect to the non-inverting input of the operational amplifier in the compensation network. V o_ref Connect the inverting input terminal to meet the above requirements.

[0022] Furthermore, since the control circuit uses a 12V single-ended power supply, a DC bias needs to be superimposed on the current sampling signal to ensure the stability of the power circuit under no-load conditions. Specifically, when the converter is powered on under no-load conditions, the output current is 0. Because the control loop chip's power supply range is 0~12V, the voltage loop output voltage is always greater than 0, causing the circuit to fail to close the loop. Therefore, a constant voltage needs to be superimposed on the output current sampling value. V D .

[0023] Since the output signal amplitude range of UC3901 is 0~1.5V, the transformer ratio needs to be adjusted according to the triangular carrier voltage range in the main control circuit.

[0024] In the technical solution of this invention, when the phase-shifted full-bridge converter enters a steady state (Δ V o After =0), the output voltage v o Applying a small perturbation results in two possible adjustment processes: Δ V o >(<)0: first step: V o_ref constant, v o Decrease (increase); Step Two: ( i o + V D The voltage loop compensation network output remains unchanged. i o_ref Decrease (increase); Step 3: Output of the current loop compensation network V com_s Decrease (increase); Step 4: The amplitude of the square wave output by UC3901 increases (decreases), and after isolation by the transformer and filtering by R1 and C2, V com_p It also increases (decreases); Step 5: The triangular carrier wave in the main control circuit remains constant, therefore D Increase (decrease); Step 6: v o Increase (decrease); v o = D*V in / (2K), where K is the turns ratio of the power transformer. V in (This refers to the input voltage of the full-bridge inverter).

[0025] This invention replaces the conventional magnetic isolation drive circuit with a magnetic isolation circuit, reducing the size and weight of the circuit, while also providing a novel magnetic isolation method.

[0026] It should be noted that the above description is merely illustrative and explanatory of the present invention. Those skilled in the art should understand that any modifications and substitutions to the present invention fall within the scope of protection of the present invention.

Claims

1. A negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter, characterized in that, It includes a full-bridge inverter, a power transformer, a current doubler rectifier, a voltage and current sampling circuit, a voltage loop compensation network, a current loop compensation network, a magnetic isolation circuit, a main control circuit, and a drive circuit. The full-bridge inverter, power transformer, and current doubler rectifier constitute the power circuit of the converter, while the remaining parts constitute the control circuit. The magnetic isolation circuit includes a UC3901 chopper chip, an isolation transformer, and a rectifier filter. The UC3901 chip is used to process analog control signals above 0.45V. V com_s The signal is chopped to become an AC signal, enabling magnetically isolated transmission of the analog signal.

2. The negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that, The voltage loop compensation network receives the output voltage of the power circuit. v o and with voltage reference V o_ref Perform proportional-integral operation and output a signal. i o_ref It serves as the current reference for the voltage loop compensation network.

3. The negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that, The current loop compensation network receives the output current of the power circuit. i o The sampled signal is superimposed with a DC bias. V D Then, with the current reference i o_ref Perform proportional integrals.

4. The negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that, The magnetic isolation circuit isolates the analog control signal output by the current loop compensation network. V com_s And output analog signal V com_p Enter the main control circuit.

5. The negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that, The main control circuit outputs the analog signal from the magnetic isolation circuit. V com_p After comparing with the triangular carrier generated by the main control chip, the output drive signal is sent to the drive circuit for amplification, and then drives the four MOSFETs in the full-bridge inverter.

6. The negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that, The magnetic isolation circuit includes a UC3901 chopper chip, an isolation transformer, and a rectifier filter. The UC3901 chip is used to process analog control signals. V com_s The signal is chopped to become an AC signal, enabling magnetically isolated transmission of the analog signal.

7. The negative logic UC3901 isolation control circuit based on a phase-shifted full-bridge converter according to claim 1, characterized in that, Voltage reference in voltage loop compensation network V o_ref and the output voltage of the power circuit v o The sampling signal is reversed, and V o_ref Connect to the inverting input terminal. v o Connect to the positive input terminal.

8. A negative logic UC3901 isolation control method based on a phase-shifted full-bridge converter, characterized in that, It uses the negative logic UC3901 isolation control circuit based on the phase-shifted full-bridge converter as described in any one of claims 1 to 7, and includes the following steps: Output voltage of the power circuit v o Samples are taken and sent to the voltage loop compensation network, along with the voltage reference. V o_ref Perform proportional-integral operation; subsequently, the voltage loop compensation network outputs a signal. i o_ref As a current reference for the voltage loop compensation network, and also for the output current of the power circuit. i o Sampling is performed, and a DC bias is superimposed. V D Then, it is sent to the current loop compensation network and compared with the current reference. i o_ref Perform proportional-integral operation; analog control signal output by the current loop compensation network. V com_s After isolation by a magnetic isolation circuit, the output analog signal V com_p The signal enters the main control circuit, is compared with the triangular carrier generated by the main control chip, and then outputs a drive signal to the drive circuit for amplification, and then drives the four MOSFETs in the full-bridge inverter.

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