Control circuit for automotive pdlc variable tint sunroof

Abstract

The utility model relates to the technical field of automobile sunroof, especially a kind of control circuit for automobile PDLC color-changing awning, including MCU main control unit, LIN communication module, input filter module, signal detection module, flyback boost module, isolator, H bridge inverter module and secondary voltage stabilizer, MCU main control unit is connected with automobile BCM by LIN communication module, MCU main control unit is sequentially connected with PDLC color-changing awning by isolator and H bridge inverter module, MCU main control unit and LIN communication module are all connected with automobile battery by input filter module, signal detection module is connected with MCU main control unit, input filter module and flyback boost module respectively, input filter module is connected with flyback boost module, flyback boost module is connected with H bridge inverter module and secondary voltage stabilizer respectively, secondary voltage stabilizer is connected with isolator and H bridge inverter module respectively;The utility model is low in cost, high in safety and stability, and realizes the accurate control of the uniform and stable light transmittance.

Description

Technical Field

[0001] This utility model relates to the field of automotive sunroof technology, and in particular to a control circuit for an automotive PDLC color-changing sunroof. Background Technology

[0002] PDLC color-changing skylights, also known as PDLC dimming skylights, change the light transmittance of the PDLC film by applying different voltages to the PDLC film in the skylight glass interlayer, thereby altering the light transmission performance of the skylight glass.

[0003] PDLC films require AC36-48V for driving, with peak voltages of 50.4-67.2V. Existing automotive controller circuits typically employ a BOOST boost + H-bridge inverter scheme. This involves first boosting the input DC12V to DC60-80V using a BOOST boost circuit, and then converting the DC60-80V to AC36-48V using an H-bridge inverter. The inverter modulation wave uses a unipolar SPWM wave. This scheme has the following drawbacks:

[0004] (1) The boost ratio required by the PDLC control circuit is usually high. Using the BOOST boost circuit for boost control loop is prone to instability. Moreover, the BOOST boost circuit has no isolation effect. The high voltage of the AC / DC in the later stage can easily affect the low voltage of the DC in the previous stage, causing interference or even damage to the components of the previous stage circuit, and the cost is high.

[0005] (2) Without a feedback control circuit, the system cannot detect the actual transmittance of the PDLC film.

[0006] (3) The unipolar SPWM wave has a zero-crossing oscillation problem, which may cause a short-term sudden change in the transmittance of the PDLC film. Utility Model Content

[0007] The technical problem to be solved by this utility model is to overcome the shortcomings of the existing technology and provide a control circuit for automotive PDLC color-changing sunroof that is low in cost, highly safe and stable, has uniform and stable light transmittance, and achieves precise control of light transmittance.

[0008] The technical solution adopted by this utility model to solve its technical problem is: a control circuit for a car PDLC color-changing sunroof, including an MCU main control unit, a LIN communication module, an input filtering module, a signal detection module, a flyback boost module, an isolator, an H-bridge inverter module, and a secondary regulator. The MCU main control unit is connected to the car BCM through the LIN communication module. The MCU main control unit is connected to the PDLC color-changing sunroof in sequence through the isolator and the H-bridge inverter module. Both the MCU main control unit and the LIN communication module are connected to the car battery through the input filtering module. The signal detection module is connected to the MCU main control unit, the input filtering module, and the flyback boost module respectively. The input filtering module is connected to the flyback boost module. The flyback boost module is connected to the H-bridge inverter module and the secondary regulator respectively. The secondary regulator is connected to the isolator and the H-bridge inverter module respectively.

[0009] Furthermore, the LIN communication module includes a LIN transceiver IC4, a diode Q11, capacitors C54 and C55, and a resistor R43; the diode Q11, capacitor C54, and resistor R43 are connected in series to form a circuit; pins 1 and 4 of the LIN transceiver IC4 are respectively connected to the MCU main control unit, and its pin 7 is connected to the input filtering module; the common terminal of the diode Q11 and resistor R43 is connected to pin 6 of the LIN transceiver IC4, and the common terminal of the capacitor C54 and resistor R43 is connected to the automotive BCM; the capacitor C55 is connected in parallel with the diode Q11.

[0010] Furthermore, the input filtering module includes a primary voltage regulator IC3, a TVS diode T2, a reverse-biased MOSFET Q1, an inductor L6, a resistor R8, a CLC filter circuit, and a voltage level detection circuit. One end of the CLC filter circuit is connected to the automotive battery through the reverse-biased MOSFET Q1, and the other end is connected to the voltage level detection circuit. Pin 1 of the primary voltage regulator IC3 is connected to the MCU main control unit through the inductor L6, and pin 6 is connected to the LIN communication module, the flyback boost module, and the common terminal of the CLC filter circuit and the voltage level detection circuit, respectively. One end of the TVS diode T2 is connected to the gate of the reverse-biased MOSFET Q1 through the resistor R8, and the other end is connected to the common terminal of the reverse-biased MOSFET Q1 and the automotive battery.

[0011] Furthermore, the signal detection module includes an operational amplifier IC1A, a photodiode D4, an AC voltage detection circuit, and a voltage control circuit; pin 1 of the operational amplifier IC1A is connected to the MCU main control unit, and pin 2 is connected to pin 3 of the operational amplifier IC1A through the photodiode D4; one end of the AC voltage detection circuit is connected to the MCU main control unit, and the other end is connected to the operational amplifier IC1A; one end of the voltage control circuit is connected to the MCU main control unit, and the other end is connected to the flyback boost module.

[0012] Furthermore, the AC voltage detection circuit includes an optocoupler driver Q9, a capacitor C50, and a resistor R38; pin 1 of the optocoupler driver Q9 is connected to pin 2 of the optocoupler driver Q9 in sequence through capacitor C50 and resistor R38; pin 3 of the optocoupler driver Q9 is connected to the MCU main control unit, and pin 4 of the optocoupler driver Q9 is connected to the operational amplifier IC1A.

[0013] Furthermore, the voltage control circuit includes an optocoupler driver Q7 and resistors R22, R23, R24, R25 and R26; pin 1 of the optocoupler driver Q7 is connected to the MCU main control unit through resistors R22, R23, R24, R25 and R26 respectively, and pin 4 is connected to the flyback boost module.

[0014] Further, the flyback boost module includes a control chip IC2, a transformer T1, transistors Q3, Q4, Q5A, diodes D1, D3, inductors L1, L3, and resistors R7, R11, R13, R17, R19, and R33. Pin 3 of the control chip IC2 is connected to terminal 3 of the transformer T1 via resistor R17 and transistor Q5A, and pin 12 is connected to the source of transistor Q3 via resistor R11. The gate of transistor Q3 is connected to the source of the transistor via resistor R7. The collector and drain of transistor Q4 are connected to the input filter module; the base of transistor Q4 is connected to the MCU main control unit through resistor R13; pin 11 of control chip IC2 is connected to the MCU main control unit through resistor R19; terminal 1 of transformer T1 is connected to the input filter module, and terminal 4 is connected to the signal detection module in sequence through diode D1, inductor L1 and resistor R33; terminal 6 of transformer T1 is connected to the secondary regulator in sequence through diode D3 and inductor L3.

[0015] Further, the H-bridge inverter module includes pre-driver IC8, IC9, MOSFETs Q12A, Q12B, Q13A, Q13B, resistors R57, R58, R67, R68, and an LC filter circuit; pins 7 and 8 of driver IC8 are connected to isolators; pins 7 and 8 of pre-driver IC9 are connected to isolators; the source of MOSFET Q12A is connected to the drain of MOSFET Q12B, and its drain is connected to the drain of MOSFET Q13A; the common terminal of MOSFETs Q12A and Q12B is connected to pin 5 of pre-driver IC8; the source of MOSFET Q12B is connected to the source of MOSFET Q13B, and its gate is connected through resistor R6. 7. Connect to pin 10 of pre-driver IC8; the drain of MOSFET Q13B is connected to the source of MOSFET Q13A, and its gate is connected to pin 10 of pre-driver IC9 through resistor R68; the common terminal of MOSFETs Q13A and Q13B is connected to pin 5 of pre-driver IC9; the gate of MOSFET Q12A is connected to pin 4 of pre-driver IC8 through resistor R57; the gate of MOSFET Q13A is connected to pin 4 of pre-driver IC9 through resistor R58; one end of the LC filter circuit is connected to the common terminal of MOSFETs Q12A and Q12B and the common terminal of MOSFETs Q13A and Q13B respectively, and the other end is connected to the PDLC color-changing sky screen.

[0016] Furthermore, the LC filter circuit includes inductors L9 and L10, capacitors C75 and C78, ​​and resistors R61 and R62; one end of inductor L9 is connected to the common terminal of MOSFETs Q12A and Q12B through resistor R61, and the other end is connected to a high-voltage ground signal through capacitor C75; one end of inductor L10 is connected to the common terminal of MOSFETs Q13A and Q13B through resistor R62, and the other end is connected to a high-voltage ground signal through capacitor C78; the common terminal of inductor L9 and capacitor C75 and the common terminal of inductor L10 and capacitor C78 are respectively connected to the PDLC color-changing canopy.

[0017] Furthermore, the secondary regulator includes a control chip IC5, a transistor Q10, a diode D6, and an inductor L7; pin 2 of the control chip IC5 is connected to an isolator via diode D6 and transistor Q10 in sequence, and pin 4 is connected to an H-bridge inverter module via inductor L7; pin 3 of the control chip IC5 is connected to a flyback boost module.

[0018] The beneficial effects of this utility model are:

[0019] (1) This utility model divides the entire power system into primary and secondary parts through the flyback boost module and isolator, so that the two circuits will not interfere with each other. Thus, the DC high voltage and AC voltage of the flyback boost module will not affect the front circuit. It has low cost and high safety and stability.

[0020] (2) This utility model detects the output AC voltage value through the AC voltage detection circuit and transmits it to the MCU main control unit to determine whether there are problems such as abnormal output voltage. The operational amplifier IC1A and the photodiode D4 detect the intensity of the internal light transmitted through the PDLC glass and transmit it to the MCU main control unit. The MCU main control unit combines the intensity of the external light in the LIN data transmitted by the LIN communication module to calculate the current transmittance of the PDLC film. The MCU main control unit sets the output voltage of the flyback boost module through the voltage control circuit, thereby realizing the precise control of the transmittance of the PDLC film and ensuring that the transmittance is not too high or too low.

[0021] (3) This utility model outputs two complementary bipolar SPWM waves simultaneously through the MCU main control unit and transmits them to the pre-driver through the isolator. The pre-driver controls the on / off of the H-bridge in the H-bridge inverter module according to the SPWM signal to perform two-phase SPWM inverter conversion and realize bipolar SPWM modulation, thereby avoiding short-term sudden changes in the transmittance of the PDLC film and ensuring that the transmittance of the PDLC film is more uniform and stable. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram of the principle framework of this utility model;

[0024] Figure 2 This is a circuit diagram of the MCU main control unit in this utility model;

[0025] Figure 3 This is the circuit diagram of the LIN transceiver IC4 in this utility model;

[0026] Figure 4 This is a circuit diagram of the filter protection network in this utility model;

[0027] Figure 5 This is a circuit diagram of the CLC filter circuit in this utility model;

[0028] Figure 6 This is the circuit diagram of the primary voltage regulator IC3 in this utility model;

[0029] Figure 7 This is the circuit diagram of the operational amplifier IC1A in this utility model;

[0030] Figure 8 This is a circuit diagram of the AC voltage detection circuit in this utility model;

[0031] Figure 9 This is a circuit diagram of the voltage control circuit in this utility model;

[0032] Figure 10 This is the circuit diagram of the flyback boost module in this utility model;

[0033] Figure 11 This is the circuit diagram of the isolator in this utility model;

[0034] Figure 12 This is the circuit diagram of the H-bridge inverter module in this utility model;

[0035] Figure 13 This is the circuit diagram of the secondary voltage regulator in this utility model;

[0036] Figure 14 It is a half-wave voltage waveform diagram of sinusoidal AC;

[0037] Figure 15 This is a schematic diagram of the unipolar SPWM modulation principle;

[0038] Figure 16 This is a schematic diagram of the bipolar SPWM modulation principle;

[0039] Figure 17 This is a voltage waveform obtained using this invention.

[0040] In the diagram: 100, MCU main control unit; 200, LIN communication module; 300, input filtering module; 400, signal detection module; 500, flyback boost module; 600, isolator; 700, H-bridge inverter module; 800, secondary regulator; 900, connector. Detailed Implementation

[0041] The present invention will now be further described with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention in a schematic manner, and therefore only show the components relevant to the present invention.

[0042] like Figure 1As shown, a control circuit for a car PDLC color-changing sunroof includes an MCU main control unit 100, a LIN communication module 200, an input filtering module 300, a signal detection module 400, a flyback boost module 500, an isolator 600, an H-bridge inverter module 700, and a secondary regulator 800. The MCU main control unit 100 is connected to the car's BCM (Body Control Module) via the LIN communication module 200. The MCU main control unit 100 is connected to the PDLC via the isolator 600 and the H-bridge inverter module 700. The color-changing roof is connected to the car battery via the input filter module 300, with the MCU main control unit 100 and LIN communication module 200 both connected. The signal detection module 400 is connected to the MCU main control unit 100, the input filter module 300, and the flyback boost module 500. The input filter module 300 is connected to the flyback boost module 500. The flyback boost module 500 is connected to the H-bridge inverter module 700 and the secondary regulator 800. The secondary regulator 800 is connected to the isolator 600 and the H-bridge inverter module 700.

[0043] Specifically, the LIN communication module 200 and the input filter module 300 are connected to the vehicle BCM and the vehicle battery respectively via connector 900.

[0044] The entire power system is divided into primary and secondary parts by using flyback boost module 500 and isolator 600, so that the two circuits will not interfere with each other. This ensures that the DC high voltage and AC voltage after flyback boost module 500 will not affect the front circuit, resulting in low cost and high safety and stability.

[0045] like Figure 2 As shown, the MCU main control unit 100 includes a microcontroller IC6. The microcontroller IC6 receives message signals transmitted by the LIN communication module 200 and voltage circuit data from other ports, and controls the operation of the flyback boost module 500 and the SPWM wave through an internal algorithm.

[0046] like Figure 3 and Figure 4 As shown, the LIN communication module 200 includes a LIN transceiver IC4, a diode Q11, capacitors C54 and C55, and a resistor R43. Diode Q11, capacitor C54, and resistor R43 are connected in series to form a circuit. Pins 1 and 4 of the LIN transceiver IC4 are connected to the MCU main control unit 100, and pin 7 is connected to the input filter module 300. The common terminal of diode Q11 and resistor R43 is connected to pin 6 of the LIN transceiver IC4, and the common terminal of capacitor C54 and resistor R43 is connected to the automotive BCM. Capacitor C55 is connected in parallel with diode Q11.

[0047] The LIN transceiver IC4 is responsible for receiving message information from the vehicle's LIN nodes, converting the LIN message information into UART signals, and transmitting them to the MCU main control unit 100 for identification. Diode Q11, capacitors C54 and C55, and resistor R43 form a filter protection network to filter out interference signals on the LIN signal line.

[0048] like Figure 5 and Figure 6 As shown, the input filtering module 300 includes a primary voltage regulator IC3, a TVS diode T2, a reverse-biased MOSFET Q1, an inductor L6, a resistor R8, a CLC filter circuit, and a voltage level detection circuit. One end of the CLC filter circuit is connected to the automotive battery through the reverse-biased MOSFET Q1, and the other end is connected to the voltage level detection circuit. Pin 1 of the primary voltage regulator IC3 is connected to the MCU main control unit 100 through the inductor L6, and pin 6 is connected to the LIN communication module 200, the flyback boost module 500, and the common terminal of the CLC filter circuit and the voltage level detection circuit, respectively. One end of the TVS diode T2 is connected to the gate of the reverse-biased MOSFET Q1 through the resistor R8, and the other end is connected to the common terminal of the reverse-biased MOSFET Q1 and the automotive battery.

[0049] Specifically, the CLC filter circuit includes inductor L2 and capacitors C17, C18, C21, C22, C23, C24, C26, and C27, used to filter out high-frequency interference; one end of inductor L2 is connected to the drain of the reverse-biased MOSFET Q1, and the other end is connected to the voltage level detection circuit; one end of capacitor C17 is connected to the common terminal of inductor L2 and the voltage level detection circuit, and the other end is grounded through capacitor C27; one end of capacitor C18 is connected to inductor L2 and the reverse-biased MOSFET Q1. The common terminal of the circuit is connected to the inductor L2, and its other end is grounded through capacitor C26; one end of capacitor C21 is connected to the common terminal of the inductor L2 and the reverse-biased MOSFET Q1, and its other end is grounded; one end of capacitor C22 is connected to the common terminal of the inductor L2 and the reverse-biased MOSFET Q1, and its other end is grounded; one end of capacitor C23 is connected to the common terminal of the inductor L2 and the level voltage detection circuit, and its other end is grounded; one end of capacitor C24 is connected to the common terminal of the inductor L2 and the level voltage detection circuit, and its other end is grounded. The level voltage detection circuit includes capacitor C29, resistors R6 and R9; one end of resistor R6 is connected to the other end of the inductor L2, and its other end is grounded through resistor R9; capacitor C29 is connected in parallel with resistor R9.

[0050] The primary voltage regulator IC3 is used to convert the car battery voltage to DC 5V for use by the MCU main control unit 100 and other low-voltage devices (such as LIN transceiver IC4); the TVS diode T2 is used to prevent the circuit from being affected by battery voltage spikes; the anti-reverse MOSFET Q1 is used to prevent the circuit from being damaged by large current when VBAT and GND are reversed; the level voltage detection circuit shuts down the circuit when it detects that the level voltage is not between DC 9-16V to prevent the circuit from being damaged by abnormal levels.

[0051] like Figures 7-9 As shown, the signal detection module 400 includes an operational amplifier IC1A, a photodiode D4, an AC voltage detection circuit, and a voltage control circuit. Pin 1 of the operational amplifier IC1A is connected to the MCU main control unit 100, and pin 2 is connected to pin 3 of the operational amplifier IC1A through the photodiode D4. One end of the AC voltage detection circuit is connected to the MCU main control unit 100, and the other end is connected to the operational amplifier IC1A. One end of the voltage control circuit is connected to the MCU main control unit 100, and the other end is connected to the flyback boost module 500.

[0052] Specifically, the stronger the received light, the greater the current flowing through photodiode D4; operational amplifier IC1A amplifies the weak current signal generated by photodiode D4 and transmits it to the MCU main control unit 100 for identification; the AC voltage detection circuit includes optocoupler driver Q9, capacitor C50, and resistor R38, used to detect the output AC voltage value; pin 1 of optocoupler driver Q9 is connected to pin 2 of optocoupler driver Q9 through capacitor C50 and resistor R38; pin 3 of optocoupler driver Q9 is connected to the MCU main control unit 100, and its pin 4 is connected to operational amplifier IC1A. The voltage control circuit includes optocoupler driver Q7, resistors R22, R23, R24, R25, and R26, used to control the output voltage; pin 1 of optocoupler driver Q7 is connected to the MCU main control unit 100 through resistors R22, R23, R24, R25, and R26, and its pin 4 is connected to flyback boost module 500.

[0053] The AC voltage detection circuit detects the output AC voltage value and transmits it to the MCU main control unit 100 to determine if there are any abnormal output voltage issues. Operational amplifier IC1A and photodiode D4 detect the intensity of internal light transmitted through the PDLC glass and transmit this information to the MCU main control unit 100. The MCU main control unit 100, combined with the external light intensity data transmitted through the LIN communication module 200, calculates the current transmittance of the PDLC film. The MCU main control unit 100 sets the output voltage of the flyback boost module 500 through the voltage control circuit, thereby achieving precise control of the PDLC film transmittance and ensuring that the transmittance is neither too high nor too low. The MCU main control unit 100 pulls high the five I / O ports (IO1-5) of the optocoupler driver Q7, controlling the V_SET pin (pin 4) of the optocoupler driver Q7 to output six different voltages, thus setting six different voltage levels for the flyback boost module 500. The table below shows the relationship between each voltage level and the transmittance of the PDLC film:

[0054] Voltage Vac 0 10 16 36 42 48 transmittance % 51 65 76 81 84 88

[0055] like Figure 10 As shown, the flyback boost module 500 includes a control chip IC2, a transformer T1, transistors Q3, Q4, Q5A, diodes D1, D3, inductors L1, L3, and resistors R7, R11, R13, R17, R19, and R33, used to generate the DC high voltage required for inverter operation. Pin 3 of the control chip IC2 is connected to terminal 3 of the transformer T1 via resistor R17 and transistor Q5A, and pin 12 is connected to the source of transistor Q3 via resistor R11. The gate of transistor Q3 is connected to the transistor via resistor R7. The collector and drain of transistor Q4 are connected to the input filter module 300; the base of transistor Q4 is connected to the MCU main control unit 100 through resistor R13; pin 11 of control chip IC2 is connected to the MCU main control unit 100 through resistor R19; terminal 1 of transformer T1 is connected to the input filter module 300, and terminal 4 is connected to the signal detection module 400 in sequence through diode D1, inductor L1 and resistor R33; terminal 6 of transformer T1 is connected to the secondary regulator 800 in sequence through diode D3 and inductor L3.

[0056] Transformer T1 is used to isolate the power transmission between the primary and secondary circuits; MCU main control unit 100 controls the operation and sleep of control chip IC2 through the Enable terminal of resistor R13; the PGOOD terminal (i.e., pin 11) of control chip IC2 is the power feedback terminal. If a fault such as output overvoltage or output overpower occurs, the level of PGOOD terminal will be flipped. MCU main control unit 100 will recognize the flip and perform corresponding protection processing.

[0057] The +60V output, controlled by the flyback boost module 500, is the main power output voltage, used to output high DC voltages that require inversion. This voltage can be adjusted within the range of 0-80V. The boost ratio in the flyback boost module 500 is affected by the transformer turns ratio; theoretically, the smaller the transformer turns ratio, the higher the boost capability.

[0058] like Figure 11 and Figure 12 As shown, the H-bridge inverter module 700 includes pre-driver IC8, IC9, MOSFETs Q12A, Q12B, Q13A, Q13B, resistors R57, R58, R67, R68, and an LC filter circuit. Pins 7 and 8 of driver IC8 are connected to isolator 600. Pins 7 and 8 of pre-driver IC9 are also connected to isolator 600. The source of MOSFET Q12A is connected to the drain of MOSFET Q12B, and its drain is connected to the drain of MOSFET Q13A. The common terminal of MOSFETs Q12A and Q12B is connected to pin 5 of pre-driver IC8. The source of MOSFET Q12B is connected to the source of MOSFET Q13B, and its gate is connected to the LC filter circuit. Resistor R67 is connected to pin 10 of pre-driver IC8; the drain of MOSFET Q13B is connected to the source of MOSFET Q13A, and its gate is connected to pin 10 of pre-driver IC9 through resistor R68; the common terminal of MOSFETs Q13A and Q13B is connected to pin 5 of pre-driver IC9; the gate of MOSFET Q12A is connected to pin 4 of pre-driver IC8 through resistor R57; the gate of MOSFET Q13A is connected to pin 4 of pre-driver IC9 through resistor R58; one end of the LC filter circuit is connected to the common terminal of MOSFETs Q12A and Q12B and the common terminal of MOSFETs Q13A and Q13B respectively, and the other end is connected to the PDLC color-changing sky screen.

[0059] Specifically, the pre-drivers IC8 and IC9 mainly receive two complementary bipolar SPWM1 and SPWM2 signals and output HO1, HO2, LO1, and LO2 to control the MOSFETs Q12A, Q12B, Q13A, and Q13B to turn on and off in a specific sequence. The LC filter circuit includes inductors L9 and L10, capacitors C75 and C78, ​​and resistors R61 and R62, which are used to filter out the high-frequency carrier wave output from the H-bridge to obtain the required 50Hz AC voltage. One end of inductor L9 is connected to the common terminal of MOSFETs Q12A and Q12B through resistor R61, and the other end is connected to the high-voltage ground signal through capacitor C75. One end of inductor L10 is connected to the common terminal of MOSFETs Q13A and Q13B through resistor R62, and the other end is connected to the high-voltage ground signal through capacitor C78. The common terminals of inductor L9 and capacitor C75, and the common terminals of inductor L10 and capacitor C78 are respectively connected to the PDLC color-changing canopy.

[0060] The MCU main control unit 100 simultaneously outputs two complementary bipolar SPWM waves, which are transmitted to the pre-driver IC8 and IC9 through the isolator 600. The pre-driver IC8 and IC9 control the on / off state of the H-bridge in the H-bridge inverter module 700 according to the SPWM signal to perform two-phase SPWM inversion conversion and realize bipolar SPWM modulation. This avoids short-term sudden changes in the transmittance of the PDLC film and ensures that the transmittance of the PDLC film is more uniform and stable.

[0061] like Figure 13 As shown, the secondary regulator 800 includes a control chip IC5, a transistor Q10, a diode D6, and an inductor L7; pin 2 of the control chip IC5 is connected to the isolator 600 through diode D6 and transistor Q10 in sequence, and pin 4 is connected to the H-bridge inverter module 700 through inductor L7; pin 3 of the control chip IC5 is connected to the flyback boost module 500.

[0062] The principle of SPWM inversion is as follows:

[0063] SPWM conversion is based on the principle of area equivalence, which converts... Figure 14 The sinusoidal AC half-wave voltage is divided into n equal parts. The sinusoidal half-wave can be regarded as a waveform composed of n interconnected rectangular pulses, and the pulse voltage amplitude changes according to a sinusoidal law. The larger n is, the closer it is to a sine wave.

[0064] Since it is difficult to control the generation of pulse voltages with constant width, constant frequency, and continuously varying amplitude according to a sinusoidal law, it can be equivalent to controlling the generation of pulse voltages with constant amplitude, constant frequency, and continuously varying rectangular pulse width according to a sinusoidal law, such as... Figure 14 As shown.

[0065] SPWM inverter modulation commonly uses unipolar SPWM modulation (such as...). Figure 15 ) and bipolar SPWM modulation (such as Figure 16 Unipolar SPWM modulation has a zero-crossing oscillation problem, which can easily lead to sudden changes in the transmittance of PDLC film; while bipolar SPWM modulation has a smooth and continuous waveform, and the transmittance of PDLC film is more stable. Therefore, this application uses bipolar SPWM modulation.

[0066] This application first uses a flyback boost module 500 to convert the 12V input DC voltage into a 60-80V DC high voltage (the specific value depends on the required light transmittance); then, the H-bridge inverter module 700 converts this DC high voltage into a pulse voltage with a frequency of 20kHz, a voltage amplitude of 60-80V, and a pulse width varying according to a 50Hz sinusoidal AC current pattern. This pulse voltage cannot be directly used for the PDLC color-changing pylon; it must first pass through an LC filter circuit to filter out the 20kHz high-frequency carrier, retaining the low-frequency portion to obtain a 50Hz AC voltage. The voltage waveform is as follows: Figure 17As shown, V(N006,N007) is the output pulse voltage of the H-bridge, and V(N009,N011) is the 50Hz AC voltage after passing through the LC filter circuit.

[0067] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They should not be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.

Claims

1. A control circuit for a car PDLC color-changing panoramic sunroof, characterized in that: The system includes an MCU main control unit (100), a LIN communication module (200), an input filtering module (300), a signal detection module (400), a flyback boost module (500), an isolator (600), an H-bridge inverter module (700), and a secondary regulator (800). The MCU main control unit (100) is connected to the vehicle's BCM via the LIN communication module (200). The MCU main control unit (100) is connected to the PDLC color-changing panoramic sunroof via the isolator (600) and the H-bridge inverter module (700). Both the LIN communication module (200) and the input filter module (300) are connected to the car battery. The signal detection module (400) is connected to the MCU main control unit (100), the input filter module (300) and the flyback boost module (500) respectively. The input filter module (300) is connected to the flyback boost module (500). The flyback boost module (500) is connected to the H-bridge inverter module (700) and the secondary regulator (800) respectively. The secondary regulator (800) is connected to the isolator (600) and the H-bridge inverter module (700) respectively.

2. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 1, characterized in that: The LIN communication module (200) includes a LIN transceiver IC4, a diode Q11, capacitors C54 and C55, and a resistor R43. The diode Q11, capacitor C54, and resistor R43 are connected in series to form a circuit. Pins 1 and 4 of the LIN transceiver IC4 are connected to the MCU main control unit (100), and pin 7 is connected to the input filter module (300). The common terminal of the diode Q11 and resistor R43 is connected to pin 6 of the LIN transceiver IC4, and the common terminal of the capacitor C54 and resistor R43 is connected to the automotive BCM. The capacitor C55 is connected in parallel with the diode Q11.

3. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 1, characterized in that: The input filtering module (300) includes a primary voltage regulator IC3, a TVS diode T2, a reverse-biased MOSFET Q1, an inductor L6, a resistor R8, a CLC filter circuit, and a voltage level detection circuit. One end of the CLC filter circuit is connected to the automotive battery through the reverse-biased MOSFET Q1, and the other end is connected to the voltage level detection circuit. Pin 1 of the primary voltage regulator IC3 is connected to the MCU main control unit (100) through the inductor L6, and pin 6 is connected to the LIN communication module (200), the flyback boost module (500), and the common terminal of the CLC filter circuit and the voltage level detection circuit, respectively. One end of the TVS diode T2 is connected to the gate of the reverse-biased MOSFET Q1 through the resistor R8, and the other end is connected to the common terminal of the reverse-biased MOSFET Q1 and the automotive battery.

4. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 1, characterized in that: The signal detection module (400) includes an operational amplifier IC1A, a photodiode D4, an AC voltage detection circuit, and a voltage control circuit. Pin 1 of the operational amplifier IC1A is connected to the MCU main control unit (100), and pin 2 is connected to pin 3 of the operational amplifier IC1A through the photodiode D4. One end of the AC voltage detection circuit is connected to the MCU main control unit (100), and the other end is connected to the operational amplifier IC1A. One end of the voltage control circuit is connected to the MCU main control unit (100), and the other end is connected to the flyback boost module (500).

5. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 4, characterized in that: The AC voltage detection circuit includes an optocoupler driver Q9, a capacitor C50, and a resistor R38; pin 1 of the optocoupler driver Q9 is connected to pin 2 of the optocoupler driver Q9 in sequence through capacitor C50 and resistor R38; pin 3 of the optocoupler driver Q9 is connected to the MCU main control unit (100), and pin 4 of the optocoupler driver Q9 is connected to the operational amplifier IC1A.

6. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 4, characterized in that: The voltage control circuit includes an optocoupler driver Q7 and resistors R22, R23, R24, R25 and R26; pin 1 of the optocoupler driver Q7 is connected to the MCU main control unit (100) through resistors R22, R23, R24, R25 and R26 respectively, and pin 4 is connected to the flyback boost module (500).

7. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 1, characterized in that: The flyback boost module (500) includes a control chip IC2, a transformer T1, transistors Q3, Q4, Q5A, diodes D1, D3, inductors L1, L3, and resistors R7, R11, R13, R17, R19, and R33. Pin 3 of the control chip IC2 is connected to terminal 3 of the transformer T1 via resistor R17 and transistor Q5A, and pin 12 is connected to the source of transistor Q3 via resistor R11. The gate of transistor Q3 is connected to the collector of transistor Q4 via resistor R7, and its drain is connected to… Input filtering module (300); the base of transistor Q4 is connected to MCU main control unit (100) through resistor R13; pin 11 of control chip IC2 is connected to MCU main control unit (100) through resistor R19; terminal 1 of transformer T1 is connected to input filtering module (300), and terminal 4 is connected to signal detection module (400) in sequence through diode D1, inductor L1 and resistor R33; terminal 6 of transformer T1 is connected to secondary regulator (800) in sequence through diode D3 and inductor L3.

8. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 3, characterized in that: The H-bridge inverter module (700) includes pre-driver IC8, IC9, MOSFETs Q12A, Q12B, Q13A, Q13B, resistors R57, R58, R67, R68, and an LC filter circuit. Pins 7 and 8 of driver IC8 are connected to isolator (600). Pins 7 and 8 of pre-driver IC9 are connected to isolator (600). The source of MOSFET Q12A is connected to the drain of MOSFET Q12B, and its drain is connected to the drain of MOSFET Q13A. The common terminal of MOSFETs Q12A and Q12B is connected to pin 5 of pre-driver IC8. The source of MOSFET Q12B is connected to the source of MOSFET Q13B, and its gate is connected to the common terminal of MOSFET Q12A. A resistor R67 is connected to pin 10 of the pre-driver IC8; the drain of the MOSFET Q13B is connected to the source of the MOSFET Q13A, and its gate is connected to pin 10 of the pre-driver IC9 through a resistor R68; the common terminal of the MOSFETs Q13A and Q13B is connected to pin 5 of the pre-driver IC9; the gate of the MOSFET Q12A is connected to pin 4 of the pre-driver IC8 through a resistor R57; the gate of the MOSFET Q13A is connected to pin 4 of the pre-driver IC9 through a resistor R58; one end of the LC filter circuit is connected to the common terminal of the MOSFETs Q12A and Q12B and the common terminal of the MOSFETs Q13A and Q13B respectively, and the other end is connected to the PDLC color-changing sky screen.

9. The control circuit for an automotive PDLC color-changing panoramic sunroof according to claim 8, characterized in that: The LC filter circuit includes inductors L9 and L10, capacitors C75 and C78, ​​and resistors R61 and R62. One end of inductor L9 is connected to the common terminal of MOSFETs Q12A and Q12B through resistor R61, and the other end is connected to a high-voltage ground signal through capacitor C75. One end of inductor L10 is connected to the common terminal of MOSFETs Q13A and Q13B through resistor R62, and the other end is connected to a high-voltage ground signal through capacitor C78. The common terminal of inductor L9 and capacitor C75, and the common terminal of inductor L10 and capacitor C78 are respectively connected to the PDLC color-changing canopy.

10. The control circuit for a car PDLC color-changing panoramic sunroof according to claim 1, characterized in that: The secondary regulator (800) includes a control chip IC5, a transistor Q10, a diode D6, and an inductor L7; pin 2 of the control chip IC5 is connected to an isolator (600) via diode D6 and transistor Q10, and pin 4 is connected to an H-bridge inverter module (700) via inductor L7; pin 3 of the control chip IC5 is connected to a flyback boost module (500).

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