PWM waveform generation circuit for bidirectional DC-DC conversion

Abstract

The utility model discloses a PWM waveform generation circuit for bidirectional DC-DC conversion. The PWM waveform generation circuit comprises a single-chip microcomputer circuit (11), a first AND operation circuit (12) and a second AND operation circuit (13). The system is characterized in that a first output end of the single-chip microcomputer circuit (11) is configured to output a waveform PWM1, a second output end is configured to output a waveform PWM2, a third output end is configured to output a waveform PWM3, and a fourth output end is configured to output a waveform PWM4; the first output end and the fourth output end of the single-chip microcomputer circuit (11) are electrically connected with the two input ends of the second AND operational circuit (13) respectively, and the output end of the second AND operational circuit (13) is electrically connected with the PWMH input end of the switching tube driving circuit (2). And a single chip microcomputer chip with simplified functions is used, so that the cost is low.

Description

Technical Field

[0001] The utility model relates to the technical field of direct current switching power supplies, in particular to a PWM waveform generating circuit for bidirectional DC-DC conversion. Background Art

[0002] DC-DC converters are widely used in power electronic equipment. In order to improve the reliability and conversion efficiency of the converter, it is necessary to control and optimize the dead time between the upper and lower arm switches of the DC-DC converter.

[0003] The DC-DC converter includes a BUCK circuit for stepping down the voltage or a BOOST circuit for stepping up the voltage, wherein the BUCK circuit is divided into an asynchronous BUCK circuit and a synchronous BUCK circuit, and the BOOST circuit is divided into an asynchronous BOOST circuit and a synchronous BOOST circuit.

[0004] The synchronous BUCK circuit consists of upper and lower bridge arm switch tubes, energy storage inductors, and output filter capacitors. When the circuit is working, the PWM signal controls the two MOS tubes to conduct alternately, thereby controlling the charging and discharging of the inductor. The difference from the asynchronous BUCK circuit architecture is that the synchronous BUCK circuit uses MOS switches to participate in freewheeling to obtain lower freewheeling power consumption than the freewheeling diode.

[0005] In the synchronous BUCK circuit, PWMH is used to represent the driving waveform of the upper bridge arm MOS Q1, and PWML is used to represent the driving waveform of the lower bridge arm MOS Q2; I L Represents the inductor current waveform, then, there is a short period of time on the PWMH and PWML waveforms. In this time interval, PWMH and PWML are both low. This time interval is the dead time. When PWMH is high and PWML is low, the upper arm tube MOS Q1 is turned on, the lower arm tube Q2 is turned off, and the inductor current rises; when PWMH is low and PWML is high, the upper arm tube MOS Q1 is turned off, the lower arm tube Q2 is turned on, and the inductor realizes freewheeling through Q2.

[0006] The existence of dead time in the BUCK circuit is because the so-called synchronization is relative. The control of the upper and lower bridge arm switches cannot be completely seamless, with one open and the other closed. Therefore, the controller follows a principle: it is better to close the upper and lower bridge arm switches at the same time to prevent the current from passing, rather than to allow the upper and lower bridge arm switches to have a chance to open at the same time, so that the current directly short-circuits from the power input end through the upper and lower bridge arm switches to the power ground. Therefore, there must be a certain dead time between the drive signals of the upper and lower bridge arm switches to prevent the power input end from short-circuiting with the power ground through the upper and lower bridge arm switches, that is, during the dead time, the upper and lower bridge arm switches are not turned on. Any controller needs to avoid the upper and lower bridge arm switches being turned on at the same time. If this state occurs, it is very easy to cause damage to the upper and lower bridge arm switches, because it is equivalent to short-circuiting the input power supply and GND through the upper and lower bridge arm switches. In order to avoid this state, it is necessary to wait for a period of time after the upper bridge arm switch Q1 is turned off before turning on the lower bridge arm switch. The state in which both the upper and lower bridge arm switches are turned off is called dead time. During the dead time, the parasitic diode of the lower bridge arm switch or the external diode connected in parallel with the lower bridge arm switch is mainly used for freewheeling.

[0007] During the dead time, the freewheeling power consumption of the switch tube is the power consumption of the parasitic diode of the lower bridge arm switch tube, that is, the forward conduction voltage drop of the diode multiplied by the freewheeling current at this time.

[0008] In the synchronous BOOST circuit, the diode D is replaced by the MOS tube Q2. When Q1 is turned on, Q2 is turned off, and when Q1 is turned off, Q2 is turned on. Q2 replaces the function of the diode. Since Q1 and Q2 can be in saturation conduction when they are turned on, the power consumption of Q2 tube will be greatly reduced, and the overall efficiency is improved. Such a synchronous on-off circuit is called a synchronous BOOST circuit. In the actual circuit, due to the inconsistency of the time delay between the MOS tubes Q1 and Q2 and the influence of the distributed capacitance and inductance of the circuit itself, when Q1 is turned on, Q2 cannot be turned off at the same time. Conversely, when Q2 is turned on, Q1 cannot be really turned off at the same time, but there is a time difference. This time difference will generate a large current and power consumption in the Q1 and Q2 loops, and will cause damage to the MOS tubes Q1 and Q2. Therefore, the dead time must also be set in the synchronous BOOST circuit.

[0009] The application number is CN202210649514.4, and the name of the invention is "A method for setting the intermittent working dead zone of SiC MOSFET Boost converter in synchronous working mode". A method for setting the intermittent working dead zone of a converter is provided, including: obtaining the actual duty cycle D, the input side voltage Vi and the output side voltage Vo of the converter, and setting the dead time before the main switch tube M1 is turned on to Tahead; obtaining relevant parameter information of the SiC MOSFET device and its driving circuit, and setting the dead time after the main switch tube M1 is turned off to Tafter. The above steps are completed within n switching cycles, and the method is executed with n cycles as a cycle time. The dead zone setting method of the present invention takes into account not only the situation that the converter works in the intermittent mode, but also the capacitive loss of SiCMOSFET and the freewheeling loss of the diode, thereby improving the efficiency of the converter in the intermittent working mode without the need for additional hardware circuits.

[0010] The patent with application number CN201811301863.7 and invention name "A dead zone setting method and its application device" provides a method for controlling the switch tube used for power output in the inverter to delay the first time to turn on and delay the second time to turn off, so as to maximize the on-time of the switch tube, improve the quality of the circuit output current, and effectively reduce harmonic distortion; at the same time, by controlling the other switch tube of complementary drive to turn off normally and delay the third time to turn on, and the third time is longer than the second time, to ensure that there is a dead zone for the complementary control signals of the two switch tubes to avoid direct conduction. In addition, when the power factor of the circuit where the two switch tubes are located changes, this method will obtain different judgment results according to the different power factors, and further set the corresponding time lengths of the two switch tubes delayed on and off under the current power factor, avoiding the problem of weakening the dead zone compensation effect due to different power factors in the prior art. This patent sets a dead time Td between the control signals of the two switching devices in the upper and lower bridge arms of the same phase; the original control signal D1 / D11 is changed to D1' / D11', so that the turned-on power device can be reliably turned off, and after a certain period of time, the turned-off power device is triggered again. During this period of time, the power devices in the upper and lower bridge arms are in the turned-off state.

[0011] The patent with application number CN202211149632.5 and invention name "A driving circuit for a high-efficiency Buck converter" provides a driving circuit including: a pass-through protection circuit, a high-side circuit and a low-side circuit; the pass-through protection circuit is connected to the high-side circuit and the low-side circuit respectively; the pass-through protection circuit is used to prevent circuit damage; the high-side circuit is used to receive the PWM signal transmitted by the pass-through protection circuit, and generate a dynamic dead time from the high side to the low side; the low-side circuit is used to receive the PWM signal transmitted by the pass-through protection circuit, and generate a dead time from the low side to the high side. This application combines the application scenario of a wide input voltage range, uses the inductor current to change the charging and discharging time of the SW node capacitor, and then realizes the dynamic adjustment of the dead time under different load current conditions, ensuring the reliability of DC-DC while reducing power loss and improving efficiency; at the same time, the narrow pulse generation circuit part is omitted to further reduce static power consumption and improve system efficiency.

[0012] In the prior art, although different methods are provided for optimizing the dead time setting, and the corresponding switch tube control waveform PWM generation methods are provided, the existing switch tube control waveform PWM generation circuit cannot be implemented using a single-chip microcomputer chip with simplified functions and low price, which limits the further reduction of the manufacturing cost of the DC-DC converter. Summary of the invention

[0013] The utility model aims to provide a bidirectional DC-DC conversion PWM waveform generating circuit constructed by using a single-chip microcomputer chip with simplified functions and low price, which can further reduce the manufacturing cost of the bidirectional DC-DC converter.

[0014] To achieve this purpose, the utility model adopts the following technical solutions:

[0015] A PWM waveform generating circuit for a bidirectional DC-DC converter comprises a single chip computer circuit (11), a first AND operation circuit (12) and a second AND operation circuit (13); the circuit is characterized in that:

[0016] The first output end of the single-chip circuit (11) is configured to output waveform PWM1, the second output end is configured to output waveform PWM2, the third output end is configured to output waveform PWM3, and the fourth output end is configured to output waveform PWM4, wherein waveform PWM1 and waveform PWM2 are a pair of pulse waveforms with the same frequency and opposite phases and adjustable duty cycle, waveform PWM3 and waveform PWM2 have the same frequency and different phase conversion time, waveform PWM4 and waveform PWM1 have the same frequency and different phase conversion time, and the duty cycle of waveforms PWM3 and PWM4 is adjustable;

[0017] The second and third output terminals of the single-chip circuit (11) are respectively electrically connected to the two input terminals of the first AND operation circuit (12), and the output terminal of the first AND operation circuit (12) is electrically connected to the PWML input terminal of the switch tube drive circuit (2); the first AND operation circuit (12) performs an AND operation on the waveform PWM2 and the waveform PWM3 to generate a waveform PWML, and the waveform PWML is converted into a switch tube drive waveform LO through the switch tube drive circuit (2);

[0018] The first and fourth output terminals of the single-chip computer circuit (11) are respectively electrically connected to the two input terminals of the second AND operation circuit (13), and the output terminal of the second AND operation circuit (13) is electrically connected to the PWMH input terminal of the switch tube drive circuit (2); the second AND operation circuit (13) performs an AND operation on the waveform PWM1 and the waveform PWM4 to generate a waveform PWMH, and the waveform PWMH is converted into a switch tube drive waveform HO via the switch tube drive circuit (2).

[0019] The beneficial effects of the utility model are:

[0020] The PWM waveform generating circuit for a bidirectional DC-DC converter provided by the utility model uses a single-chip microcomputer chip with simplified functions and low price to construct the PWM waveform generating circuit for bidirectional DC-DC conversion, thereby further reducing the manufacturing cost of the bidirectional DC-DC converter.

[0021] Other features and advantages of the present invention will be described in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the composition of a PWM waveform generating circuit capable of setting a double-channel dead time given in a specific implementation mode of the utility model;

[0023] Figure 2 It is a schematic diagram of the structure of a PWM waveform generating circuit capable of setting a double-channel dead time given in a specific embodiment of the utility model;

[0024] Figure 3 It is a waveform diagram of a PWM waveform generating circuit using PWM3 to set the dead time given in a specific embodiment of the utility model;

[0025] Figure 4 This is a waveform diagram of a PWM waveform generation circuit using PWM4 to set the dead time given in the specific implementation mode of the utility model.

[0026] Figure 5 The utility model discloses a PWM waveform generating circuit capable of setting a dual-channel dead time and used in a BUCK / BOOST bidirectional conversion circuit schematic diagram.

[0027] In the figure, 1. PWM waveform generating circuit; 11. single chip microcomputer circuit; 12. first "AND" operation circuit; 13. second "AND" operation circuit; 2. switch tube driving circuit; 3. detection circuit. DETAILED DESCRIPTION

[0028] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0029] The utility model provides a PWM waveform generating circuit for bidirectional DC-DC conversion which is constructed by using a single-chip microcomputer chip with simplified functions and low price, and can further reduce the manufacturing cost of the bidirectional DC-DC converter.

[0030] The utility model provides a PWM waveform generating circuit for a bidirectional DC-DC converter, comprising a single chip computer circuit (11), a first “AND” operation circuit (12) and a second “AND” operation circuit (13); the characteristics are:

[0031] The first output end of the single-chip circuit (11) is configured to output waveform PWM1, the second output end is configured to output waveform PWM2, the third output end is configured to output waveform PWM3, and the fourth output end is configured to output waveform PWM4, wherein waveform PWM1 and waveform PWM2 are a pair of pulse waveforms with the same frequency and opposite phases and adjustable duty cycle, waveform PWM3 and waveform PWM2 have the same frequency and different phase conversion time, waveform PWM4 and waveform PWM1 have the same frequency and different phase conversion time, and the duty cycle of waveforms PWM3 and PWM4 is adjustable;

[0032] The second and third output terminals of the single-chip circuit (11) are respectively electrically connected to the two input terminals of the first AND operation circuit (12), and the output terminal of the first AND operation circuit (12) is electrically connected to the PWML input terminal of the switch tube drive circuit (2); the first AND operation circuit (12) performs an AND operation on the waveform PWM2 and the waveform PWM3 to generate a waveform PWML, and the waveform PWML is converted into a switch tube drive waveform LO through the switch tube drive circuit (2);

[0033] The first and fourth output terminals of the single-chip computer circuit (11) are respectively electrically connected to the two input terminals of the second AND operation circuit (13), and the output terminal of the second AND operation circuit (13) is electrically connected to the PWMH input terminal of the switch tube drive circuit (2); the second AND operation circuit (13) performs an AND operation on the waveform PWM1 and the waveform PWM4 to generate a waveform PWMH, and the waveform PWMH is converted into a switch tube drive waveform HO via the switch tube drive circuit (2).

[0034] Specifically, see Figure 1 As shown, the first, second, third and fourth output terminals of the single-chip microcomputer circuit (11) are output terminals of a digital pulse waveform generating circuit within the single-chip microcomputer chip, whose period and duty cycle can be configured by an internal digital processing unit, wherein the internal circuit of the single-chip microcomputer circuit (11) corresponding to the first and second output terminals can be configured to output waveforms PWM1 and PWM2 with the same period and opposite phases.

[0035] The third output terminal of the single-chip circuit (11) is the output terminal of a digital pulse waveform generating circuit in the single-chip chip, whose period and duty cycle can be configured by an internal digital processing unit, and the waveform PWM3 outputted from the third output terminal has a different phase conversion time from the waveform PWM1 outputted from the first output terminal, and there is a definite time correspondence relationship between the phase conversion time of the waveform PWM1 and the waveform PWM3.

[0036] The fourth output terminal of the single-chip circuit (11) is an output terminal of a digital pulse waveform generating circuit in the single-chip chip whose period and duty cycle can be configured by an internal digital processing unit, and the waveform PWM4 outputted from the fourth output terminal has a different phase conversion time from the waveform PWM2 outputted from the first output terminal, and there is a definite time correspondence relationship between the phase conversion time of the waveform PWM2 and the waveform PWM4.

[0037] The switch tube driving circuit (2) is used to convert the waveform PWMH from the output end of the second AND operation circuit (13) into a switch tube driving signal HO, and to convert the waveform PWML from the output end of the first AND operation circuit (12) into a switch tube driving signal LO, wherein HO and LO meet the requirements for driving the switch tube action in terms of voltage and current characteristics.

[0038] Specifically, a specific model of the single-chip microcomputer circuit (11) is TLSR8359, which is produced by a Chinese enterprise.

[0039] Specifically, a specific model of the switch tube driving circuit (2) is NSD1224, which is produced by a Chinese enterprise.

[0040] Specifically, the phase switching time between the pulse waveform PWM1 with adjustable duty cycle and the pulse waveform PWM3 with adjustable duty cycle is different, and there is a certain time correspondence between the phase switching time of the waveform PWM1 and the waveform PWM3, and this time correspondence includes:

[0041] There is a dead time T between the pulse waveform PWM1 with adjustable duty cycle and the pulse waveform PWM3 with adjustable duty cycle, in which both are at low level. d1 and T d2 , see Figure 3 As shown, the dead time T d1 and Td2 Determines the dead time between PWMH and PWML; and,

[0042] During the dead time T d1 and T d2 In addition, the high and low levels of the duty cycle adjustable pulse waveform PWM1 and the duty cycle adjustable pulse waveform PWM3 are in opposite phases to each other; and,

[0043] The cycle time of the pulse waveform PWM1 with adjustable duty cycle is the same as the cycle time of the pulse waveform PWM3 with adjustable duty cycle.

[0044] Specifically, the phase switching time between the pulse waveform PWM2 with adjustable duty cycle and the pulse waveform PWM4 with adjustable duty cycle is different, and there is a certain time correspondence between the phase switching time of the waveform PWM2 and the waveform PWM4, and this time correspondence includes:

[0045] There is a dead time T between the pulse waveform PWM2 with adjustable duty cycle and the pulse waveform PWM4 with adjustable duty cycle, in which both are at low level. d1 and T d2 , see Figure 4 As shown, the dead time T d1 and T d2 Determines the dead time between PWMH and PWML; and,

[0046] During the dead time T d1 and T d2 In addition, the high and low levels of the duty cycle adjustable pulse waveform PWM2 and the duty cycle adjustable pulse waveform PWM4 are in opposite phases to each other; and,

[0047] The cycle time of the pulse waveform PWM2 with adjustable duty cycle is the same as the cycle time of the pulse waveform PWM4 with adjustable duty cycle.

[0048] When the PWM waveform generating circuit (1) provided in the present invention works in the BUCK circuit driving mode, see Figure 5 As shown, B2 is the input power supply of the BUCK circuit, B1 is the battery charged by the BUCK circuit, T i1 It is the input terminal of the magnetizing coil L1 in BUCK mode, T O1 It is the output terminal of the magnetizing coil L1 in BUCK mode, V in1 is the input voltage of the magnetizing coil L1, V out1 is the output voltage of the magnetizing coil L1. The high level of the pulse waveform PWML with adjustable duty cycle is used to drive the lower bridge arm switch Q2 for the energy storage inductor to enter the on state. A specific implementation method is as follows: Figure 3As shown: a pulse waveform PWML with adjustable duty cycle is used to send a high level pulse to the control end of the lower bridge arm switch tube Q2 for the energy storage inductor to continue current. The rising edge of the high level pulse lags behind the falling edge of the pulse waveform PWMH in the same cycle by a first dead time T d1 The falling edge of the high-level pulse precedes the rising edge of the pulse waveform PWMH of the next cycle by a second dead time T d2 .

[0049] Typically, the time width T of the high-level pulse sent by the pulse waveform PWML with adjustable duty cycle to the control end of the lower bridge arm switch tube Q2 for the energy storage inductor is ON , the low level duration of the pulse waveform PWMH with adjustable duty cycle and the first dead time T d1 , Second dead time T d2 OK, see Figure 3 Shown: T ON = T con -T d1 -T △ ; Among them, T ON is the time length of the lower bridge arm switch tube Q2 actually participating in the freewheeling, T con Is to use V in1 、V out1 , T inj And the relationship (V in1 -V out1 ) / V out1 =T con / T inj The solved freewheeling time, T △ It is T con The time correction amount; the T con The value is reduced by a time correction amount T △ The latter is used as the actual conduction time of the lower bridge arm switch tube Q2 to ensure that the actual conduction time of the lower bridge arm switch tube Q2 is less than or equal to the actual freewheeling time required by the energy storage inductor L1. out1 The output terminal T of the BUCK circuit energy storage inductor L1 O1 The measured value of voltage, V in1 The input terminal T of the BUCK circuit energy storage inductor L1 i1 Voltage, use Figure 4 The voltage V between the drain voltage of the upper bridge arm switch tube Q1 and the power ground GND obtained at the measurement point given in drain The measured value of V in1 , V drain With V in1 The difference between them is the saturation voltage of Q1.

[0050] In the BUCK circuit driving mode, the fourth output terminal of the single-chip microcomputer circuit (11) outputs a PWM4 waveform with a duty cycle of 1, or PWM4 maintains a high level. In this case, the waveform PWMH at the output terminal of the second AND operation circuit (13) depends on the waveform PWM1 output by the first output terminal of the single-chip microcomputer circuit (11).

[0051] When the PWM waveform generating circuit (1) provided in the present utility model works in the BOOST circuit driving mode, see Figure 5 As shown, B1 is the input power supply of the BOOST circuit, B2 is the battery charged by the BOOST circuit, and T i2 It is the input terminal of magnetizing coil L1 in BOOST mode, T O2 It is the output terminal of magnetizing coil L1 in BOOST mode, V in2 is the input voltage of the magnetizing coil L1, V out2 is the output voltage of the magnetizing coil L1. The high level of the pulse waveform PWMH with adjustable duty cycle is used to drive the upper bridge arm switch Q1 for the energy storage inductor to enter the on state. A specific implementation method is as follows: Figure 4 As shown: a pulse waveform PWMH with adjustable duty cycle is used to send a high level pulse to the control end of the upper bridge arm switch tube Q1 for the energy storage inductor to continue current. The rising edge of the high level pulse lags behind the falling edge of the pulse waveform PWML in the same cycle by a first dead time T d1 The falling edge of the high-level pulse precedes the rising edge of the pulse waveform PWML of the next cycle by a second dead time T d2 .

[0052] In the BOOST circuit driving mode, the time width T of the high-level pulse sent by the pulse waveform PWMH with adjustable duty cycle to the control end of the upper bridge arm switch tube Q1 for the freewheeling of the energy storage inductor L1 is ON , the low level duration of the pulse waveform PWML with adjustable duty cycle and the first dead time T d1 , Second dead time T d2 OK, see Figure 4 Shown: T ON = T con -T d1 -T △ ; Among them, T ON is the length of time that the upper bridge arm switch tube Q1 actually participates in the freewheeling, T con Is to use V in2 、V out2 , T inj And the relationship V in2 / (V out2 -V in2 ) = Tcon / T inj The solved freewheeling time, T △ It is T con The time correction amount; the T con The value is reduced by a time correction amount T △ The actual conduction time of the upper bridge arm switch tube Q2 is to ensure that the actual conduction time of the upper bridge arm switch tube Q1 is less than or equal to the actual freewheeling time required by the energy storage inductor L1. out2 The output terminal T of the BOOST circuit energy storage inductor O2 Voltage, from Figure 4 The voltage V between the drain voltage of the upper bridge arm switch Q1 and the power ground GND is obtained at the measurement point given in drain The measured value is V drain The measured value of V out2 , V drain With V out2 The difference between them is the saturation voltage of Q1; V in2 The input terminal T of the BOOST circuit energy storage inductor L1 i2 The measured value of voltage.

[0053] In the BOOST circuit driving mode, the third output terminal of the single-chip microcomputer circuit (11) outputs a PWM3 waveform with a duty cycle of 1, or PWM3 maintains a high level. In this case, the waveform PWML at the output terminal of the first AND operation circuit (12) depends on the waveform PWM2 output by the second output terminal of the single-chip microcomputer circuit (11).

[0054] Typically, when the duty cycle of the duty-cycle adjustable pulse waveform PWMH used to drive the upper bridge arm switch tube does not change, the time width of the high-level pulse sent by the duty-cycle adjustable pulse waveform PWML to the control end of the lower bridge arm switch tube Q2 for the energy storage inductor to continue current also remains unchanged.

[0055] The utility model provides a PWM waveform generating circuit for a bidirectional DC-DC converter, which is characterized by:

[0056] The single-chip computer circuit (11) comprises a PWM waveform parameter determination circuit, the PWM waveform parameter determination circuit comprises a digital operation circuit, a storage circuit and a PWM waveform oscillation circuit, the operation circuit performs a PWM waveform parameter determination operation in a BUCK mode under the control of an instruction stored in the storage circuit, specifically comprising the following operation steps:

[0057] The duty cycle of the waveform PWM4 output by the PWM waveform oscillation circuit corresponding to the fourth output terminal of the single-chip circuit (11) is set to 1, that is, the waveform PWM4 output by the fourth output terminal is kept at a high level;

[0058] Using the relation T ON = T con -T d1 -T △ Determine the conduction time width T of the lower bridge arm switch tube Q2 ON Value, use T ON Determine the high level time or duty cycle of the PWM waveform oscillation circuit output waveform PWM3 corresponding to the third output terminal of the single-chip circuit (11); wherein T △ It is T con Time correction value; T d1 is the first dead time between the lower bridge arm switch tube Q2 and the upper bridge arm switch tube Q1;

[0059] Use the output voltage value V of the BUCK circuit provided by the measurement circuit (3) out1 Adjust the duty cycle of waveform PWM1, and use the on-time of the upper bridge arm switch tube Q1 under the duty cycle as the magnetizing current duration T of the energy storage inductor L1. inj .

[0060] The utility model provides a PWM waveform generating circuit for a bidirectional DC-DC converter, which is characterized by:

[0061] The single-chip computer circuit (11) comprises a PWM waveform parameter determination circuit, the PWM waveform parameter determination circuit comprises a digital operation circuit, a storage circuit and a PWM waveform oscillation circuit, the operation circuit performs a PWM waveform parameter determination operation in a BOOST mode under the control of an instruction stored in the storage circuit, specifically comprising the following operation steps:

[0062] The duty cycle of the waveform PWM3 output by the PWM waveform oscillation circuit corresponding to the third output terminal of the single-chip circuit (11) is set to 1, that is, the waveform PWM3 output by the third output terminal is kept at a high level;

[0063] Using the relation T ON = T con -T d1 -T △ Determine the conduction time width T of the upper bridge arm switch tube Q1 ON Value, use T ON Determine the high level time or duty cycle of the PWM waveform oscillation circuit output waveform PWM4 corresponding to the fourth output terminal of the single-chip circuit (11); wherein T △ It is T con Time correction value; T d1 It is the first dead time between the upper bridge arm switch tube Q1 and the lower bridge arm switch tube Q2;

[0064] Use the output voltage value V of the BOOST circuit provided by the measurement circuit (3)out2 Adjust the duty cycle of waveform PWM2, and use the on-time of the lower bridge arm switch tube Q2 under the duty cycle as the magnetizing current duration T of the energy storage inductor L1. inj .

[0065] Further, see Figure 3 As shown, in the BUCK circuit driving mode, the conduction time width T of the lower bridge arm switch tube Q2 is used. ON The operation of determining the time parameter of the freewheeling tube driving waveform PWML further includes the following operations:

[0066] Use the conduction time width T of the lower bridge arm switch tube Q2 ON The value determines the high level time width or duty cycle of the freewheeling tube drive waveform PWML.

[0067] Specifically, the freewheeling tube is the lower bridge arm switch tube Q2, and the freewheeling tube driving waveform PWML is the driving waveform of the lower bridge arm switch tube Q2.

[0068] Further, see Figure 4 As shown, in the BOOST circuit driving mode, the conduction time width T of the upper bridge arm switch tube Q1 is used. ON The operation of determining the time parameter of the freewheeling tube driving waveform PWMH further includes the following operations:

[0069] The conduction time width T of the upper bridge arm switch tube Q1 is used ON The value determines the high level time width or duty cycle of the freewheeling tube drive waveform PWMH.

[0070] Specifically, the freewheeling tube is the upper bridge arm switch tube Q1, and the freewheeling tube driving waveform PWMH is the driving waveform of the upper bridge arm switch tube Q1.

[0071] Specifically, the PWML waveform and the PWMH waveform provided in this embodiment are the on-time waveforms of the lower bridge arm switch tube Q2 and the upper bridge arm switch tube Q1 respectively. The PWML waveform and the PWMH waveform need to be converted by the switch tube driving circuit (2) to generate the current and voltage parameters required to drive the lower bridge arm switch tube Q2 and the upper bridge arm switch tube Q1.

[0072] Specifically, T △ The value range is: 1 nanosecond ≤ T △ ≤2000 nanoseconds.

[0073] Furthermore, T △ The value of is calculated based on the freewheeling current duration T under different loads and ambient temperatures. con The statistical distribution of the error between the actual value of the freewheeling current duration of the energy storage inductor and T is determined conTime correction T △ To ensure that T ON +T d1 = T con -T △ The value of is less than the actual value of the freewheeling current duration of the energy storage inductor; or

[0074] To T con Time correction T △ The freewheeling current duration T con The value is between 1% and 20% of the calculated value.

[0075] Specifically, see Figure 5 As shown, in the BUCK circuit driving mode, the measuring circuit (3) measures the output voltage of the battery pack B2. The measuring point of the measuring voltage is at the drain of the upper bridge arm switch tube Q1. The measuring voltage V drain As the input terminal T of the energy storage inductor L1 in BUCK mode i1 The voltage of the measuring circuit (3) is the output terminal T of the energy storage inductor L1 of the BUCK circuit. o1 The voltage is measured and the measurement result is used as the output terminal T of the energy storage inductor L1 of the BUCK circuit. o1 The voltage V out1 ; Voltage V drain The measurement result includes the on-state voltage of the upper bridge arm switch tube Q1.

[0076] Specifically, see Figure 5 As shown, in the BOOST circuit driving mode, the measuring circuit (3) measures the output voltage of the battery pack B1, and the measuring point is at the input terminal T of the energy storage inductor L1 in the BOOST mode. i2 The measured voltage at this point is used as the input terminal T of the energy storage inductor L1 in BOOST mode. i1 The voltage V in2 , which is also the voltage across the coil of the energy storage inductor L1 in the magnetized state; the measurement circuit (3) measures the output terminal T of the energy storage inductor L1 in the BOOST mode. o2 Voltage V out2 The voltage is measured at the drain of the upper arm switch tube Q1. The voltage V drain As the output terminal T of the energy storage inductor L1 in BOOST mode o2 The voltage V out2 ; Voltage V drain The measurement result includes the on-state voltage of the upper bridge arm switch tube Q1.

[0077] The utility model provides a PWM waveform generating circuit for a bidirectional DC-DC converter, which is characterized by:

[0078] The single-chip computer circuit (11) comprises a freewheeling time determination circuit, which comprises a digital operation circuit and a memory. In a BUCK circuit driving mode, the digital operation circuit performs the following operations under the control of a storage instruction of the memory:

[0079] Using the geometric relationship (V in1 -V out1 ) / V out1 =T con / T inj Solve for the follow-up time T con The value of (V in1 -V out1 ) is the voltage across the energy storage inductor in the magnetizing state in BUCK mode, V out1 It is the voltage across the energy storage inductor in the freewheeling state, V out1 It is also the output voltage of the BUCK circuit, T con is the freewheeling time, T inj is the magnetization time.

[0080] The utility model provides a PWM waveform generating circuit for a bidirectional DC-DC converter, which is characterized by:

[0081] The single-chip computer circuit (11) comprises a freewheeling time determination circuit, which comprises a digital operation circuit and a memory. In a BOOST circuit driving mode, the digital operation circuit performs the following operations under the control of a storage instruction of the memory:

[0082] Using the geometric relationship V in2 / (V out2 -V in2 ) = T con / T inj Solve for the follow-up time T con The value of V in2 is the voltage across the energy storage inductor in the magnetized state in BOOST mode, (V out2 -V in2 ) is the voltage across the energy storage inductor in the freewheeling state, V out2 is the output voltage of the BOOST circuit, T con is the freewheeling time, T inj is the magnetization time.

[0083] The utility model provides a PWM waveform generating circuit for a bidirectional DC-DC converter, which is characterized by:

[0084] At least one of the first AND operation circuit (12) and the second AND operation circuit (13) comprises a digital integrated circuit that performs an AND operation.

[0085] Specifically, the digital integrated circuit that performs the "AND" operation includes any one of an "AND" circuit and a "NAND" circuit.

[0086] The utility model provides a PWM waveform generating circuit for a bidirectional DC-DC converter, which is characterized by:

[0087] At least one of the first AND operation circuit (12) and the second AND operation circuit (13) comprises an AND operation circuit composed of discrete diodes and resistors; wherein,

[0088] The first AND operation circuit (12) comprises diodes D3, D5, and a resistor R1, wherein the cathode of D3 is electrically connected to the third output terminal of the single-chip circuit (11), the cathode of D5 is electrically connected to the second output terminal of the single-chip circuit (11), the anodes of the diodes D3 and D5 electrically connected to each other are electrically connected to one end of the resistor R1, and the other end of the resistor R1 is electrically connected to a power supply Vcc;

[0089] The second AND operation circuit (13) comprises diodes D4, D6, and a resistor R2, wherein the cathode of D4 is electrically connected to the fourth output terminal of the single-chip computer circuit (11), the cathode of D6 is electrically connected to the first output terminal of the single-chip computer circuit (11), the anodes of the diodes D4 and D6 electrically connected to each other are electrically connected to one end of the resistor R2, and the other end of the resistor R2 is electrically connected to a power supply Vcc.

[0090] Specifically, the first AND operation circuit (12) composed of discrete diodes and resistors, see Figure 2 As shown, it comprises diodes D3, D5, and a resistor R1, wherein the cathode of D3 is electrically connected to the third output terminal of the single-chip circuit (11), the cathode of D5 is electrically connected to the second output terminal of the single-chip circuit (11), the anodes of the diodes D3 and D5 electrically connected to each other are electrically connected to one end of the resistor R1 and the PWML input terminal of the switch tube drive circuit (2), and the other end of the resistor R1 is electrically connected to the power supply Vcc;

[0091] The second AND operation circuit (13) composed of discrete diodes and resistors, see Figure 2 As shown, it comprises diodes D4, D6, and a resistor R2, wherein the cathode of D4 is electrically connected to the fourth output terminal of the single-chip circuit (11), the cathode of D6 is electrically connected to the first output terminal of the single-chip circuit (11), the anodes of the diodes D4 and D6 electrically connected to each other are electrically connected to one end of the resistor R2 and the PWMH input terminal of the switch tube drive circuit (2), and the other end of the resistor R2 is electrically connected to the power supply Vcc.

[0092] The PWM waveform generating circuit (1) provided by the utility model can be controlled by upper and lower bridge arm switch tubes in a synchronous BUCK mode and a synchronous BOOST mode in a bidirectional DC converter.

[0093] In synchronous BUCK mode, see Figure 5 As shown, the input terminal T of the inductor L1 i1 The output terminal T of the inductor L1 is electrically connected to the source of the upper bridge arm switch tube Q1 and the drain of the lower bridge arm switch tube Q2. o1 It is electrically connected to the positive electrode of the capacitor C1 and one end of the current measuring resistor Ri, the other end of the current measuring resistor Ri is electrically connected to the positive output terminal T1 of the BUCK circuit, the negative output terminal T2 of the BUCK circuit is electrically connected to the negative electrode of the capacitor C1 and the power ground GND of the BUCK circuit, a bypass diode D1 is connected in parallel between the source and the drain of the upper bridge arm switch tube Q1, a bypass diode D2 is connected in parallel between the source and the drain of the lower bridge arm switch tube Q2, the input power supply of the BUCK circuit is the battery assembly B2; F2 is a power fuse, and C2 is a power filter capacitor.

[0094] Figure 5 In the measurement circuit (3), the output terminal T of the energy storage inductor L1 is o1 The voltage of the battery pack B2 and the input voltage V drain Measurement circuit (3) is used to measure the output terminal T of the energy storage inductor L1. o1 The voltage measurement result is used as the output voltage V of the energy storage inductor out1 , the input voltage of the battery component B2 to the BUCK circuit is measured as the input voltage of the energy storage inductor V in1 ; Figure 5 In the measurement circuit (3), the voltage V at the input terminal of the energy storage inductor is measured at the drain of the upper bridge arm switch tube Q1 of the BUCK circuit. in1 The measurement result includes the on-state voltage of the upper bridge arm switch tube Q1.

[0095] The freewheeling time determination circuit included in the single-chip microcomputer circuit (11) obtains the voltage V at the output terminal of the energy storage inductor from the measurement circuit (3). out1 And the voltage V at the input of the energy storage inductor in1 The measured value is obtained from the PWM waveform parameter determination circuit included in the single-chip circuit (11) to obtain the conduction time value of the upper bridge arm switch tube Q1, and the conduction time is used as the duration T of the magnetizing current of the energy storage inductor. inj , use V in1 、V out1 , T inj And the relationship (V in1 -V out1 ) / V out1 = T con / T inj , solve for the follow-up time T con , and the freewheeling time T con The value is sent to the PWM waveform parameter determination circuit included in the single chip microcomputer circuit (11).

[0096] The PWM waveform parameter determination circuit included in the single-chip microcomputer circuit (11) sends the duration T of the inductor magnetizing current to the freewheeling time determination circuit included in the single-chip microcomputer circuit (11). inj The value of the freewheeling time T is received from the freewheeling time determination circuit con The value of the freewheeling time T con The value of determines the time parameter of the freewheeling tube Q2 driving waveform PWML. The PWM waveform generating circuit (1) uses the PWM waveform parameter determining circuit to inj The PWMH waveform is determined by the value of T con The PWML waveform determined by the value of is sent to the switch tube drive circuit (2).

[0097] The switch tube driving circuit (2) converts the PWMH sent by the PWM waveform generating circuit (1) into a signal form HO required for driving the upper bridge arm switch tube Q1, and converts the PWML sent by the PWM waveform generating circuit (1) into a signal form LO required for driving the lower bridge arm switch tube Q2.

[0098] In the synchronous BOOST mode, the PWM waveform generating circuit (1) provided by the utility model uses the electrical connection between the PWM waveform generating circuit (1) and the switch tube driving circuit (2) in the synchronous BOOST mode, and the electrical connection between the switch tube driving circuit (2) and the upper bridge arm switch Q1 and the lower bridge arm switch Q2, so that the upper bridge arm switch Q1 and the lower bridge arm switch Q2 operate in the BOOST mode, that is, while keeping the HO of the switch tube driving circuit (2) electrically connected to the gate of the upper bridge arm switch Q1, and the LO of the switch tube driving circuit (2) electrically connected to the gate of the lower bridge arm switch Q2, the operating mode of the bidirectional DC converter is switched between the BUCK mode and the BOOST mode by reconfiguring the HO and LO waveforms of the switch tube driving circuit (2).

[0099] See also Figure 5 As shown in the figure, in BOOST mode, the output terminal T of inductor L1 o2 The input terminal T of the inductor L1 is electrically connected to the source of the upper bridge arm switch tube Q1 and the drain of the lower bridge arm switch tube Q2. i2It is electrically connected to the positive electrode of the filter capacitor C1 and the positive electrode of the battery assembly B1, the drain of the upper bridge arm switch tube Q1 is electrically connected to the positive electrode of the capacitor C2 and the positive electrode of the battery assembly B2, a bypass diode D1 is connected in parallel between the source and drain of the upper bridge arm switch tube Q1, and a bypass diode D2 is connected in parallel between the source and drain of the lower bridge arm switch tube Q2. The input power supply of the BOOST circuit is the battery assembly B1; F1 is a power fuse.

[0100] See also Figure 5 As shown, the measuring circuit (3) measures the drain voltage of the upper bridge arm switch tube Q1, and the measured data is used as the output terminal T of the energy storage inductor L1 in the BOOST mode. o2 The measuring circuit (3) measures the input voltage of the battery assembly B1 to the BOOST circuit; the measuring circuit (3) measures the output terminal T of the energy storage inductor L1 o2 The voltage measurement result is used as the voltage V at the output end of the energy storage inductor out2 The measurement result of the input voltage of the battery component B1 to the BOOST circuit is used as the input terminal voltage V of the energy storage inductor in2 ; Figure 5 In the measurement circuit (3), the voltage V at the output terminal of the energy storage inductor is measured at the drain of the upper arm switch tube Q1 of the BOOST circuit. out2 The measurement result includes the on-state voltage of the upper bridge arm switch tube Q1.

[0101] In the BOOST mode, the PWM waveform generation circuit (1) adjusts the magnetizing time of the energy storage inductor L1 according to the drain voltage measurement result of the upper bridge arm switch tube Q1 and the target value of the BOOST circuit output voltage measured by the measurement circuit (3), that is, the magnetizing current duration T of the energy storage inductor L1 is adjusted. inj Adjustment is performed, that is, the duty cycle of the magnetization time of the energy storage inductor L1 is adjusted; the specific adjustment steps include: adjusting the conduction time of the lower bridge arm switch tube Q1 by adjusting the duty cycle of the waveform PWM2.

[0102] In the BOOST mode, the PWMH waveform output by the PWM waveform generating circuit (1) is used to drive the upper bridge arm switch tube Q1, but at this time, the PWMH waveform is configured as a freewheeling time control waveform; the PWML waveform output by the PWM waveform generating circuit (1) is used to drive the lower bridge arm switch tube Q2, but at this time, the PWML waveform is configured as a magnetizing time control waveform.

[0103] The technical principle of the present invention is described above in combination with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations here, technicians in this field can think of other specific implementation methods of the present invention without creative work, and these methods will fall within the protection scope of the present invention.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any technician in the field of the present invention can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed by the present invention, but the scope of protection of the present invention shall be based on the definition of the attached claims.

[0105] The PWM waveform generating circuit for a bidirectional DC-DC converter provided by the utility model uses a single-chip microcomputer chip with simplified functions and low price to construct the PWM waveform generating circuit for bidirectional DC-DC conversion, thereby further reducing the manufacturing cost of the bidirectional DC-DC converter.

Claims

1. A PWM waveform generating circuit for bidirectional DC-DC conversion, comprising a single chip computer circuit (11), a first AND operation circuit (12) and a second AND operation circuit (13); characterized in that: The first output end of the single-chip circuit (11) is configured to output waveform PWM1, the second output end is configured to output waveform PWM2, the third output end is configured to output waveform PWM3, and the fourth output end is configured to output waveform PWM4, wherein waveform PWM1 and waveform PWM2 are a pair of pulse waveforms with the same frequency and opposite phases and adjustable duty cycle, waveform PWM3 and waveform PWM2 have the same frequency and different phase conversion time, waveform PWM4 and waveform PWM1 have the same frequency and different phase conversion time, and the duty cycle of waveforms PWM3 and PWM4 is adjustable; The second and third output ends of the single-chip circuit (11) are electrically connected to the two input ends of the first AND operation circuit (12), respectively; the output end of the first AND operation circuit (12) is electrically connected to the PWML input end of the switch tube drive circuit (2); the first AND operation circuit (12) performs an AND operation on the waveform PWM2 and the waveform PWM3 to generate a waveform PWML, and the waveform PWML is converted into a switch tube drive waveform LO via the switch tube drive circuit (2); The first and fourth output ends of the single-chip circuit (11) are electrically connected to the two input ends of the second AND operation circuit (13), respectively; the output end of the second AND operation circuit (13) is electrically connected to the PWMH input end of the switch tube drive circuit (2); the second AND operation circuit (13) performs an AND operation on the waveform PWM1 and the waveform PWM4 to generate a waveform PWMH, and the waveform PWMH is converted into a switch tube drive waveform HO via the switch tube drive circuit (2).

2. The bidirectional DC-DC conversion PWM waveform generating circuit according to claim 1, characterized in that: The single-chip computer circuit (11) comprises a PWM waveform parameter determination circuit, the PWM waveform parameter determination circuit comprises a digital operation circuit, a storage circuit and a PWM waveform oscillation circuit, the operation circuit performs a PWM waveform parameter determination operation in a BUCK mode under the control of an instruction stored in the storage circuit, specifically comprising the following operation steps: The duty cycle of the waveform PWM4 output by the PWM waveform oscillation circuit corresponding to the fourth output terminal of the single-chip circuit (11) is set to 1, that is, the waveform PWM4 output by the fourth output terminal is kept at a high level; Using the relation T ON = T con -T d1 -T △ Determine the conduction time width T of the lower bridge arm switch tube Q2 ON Value, use T ON Determine the high level time or duty cycle of the PWM waveform oscillation circuit output waveform PWM3 corresponding to the third output terminal of the single-chip circuit (11); wherein T △ It is T con Time correction value; T d1 is the first dead time between the lower bridge arm switch tube Q2 and the upper bridge arm switch tube Q1; Use the output voltage value V of the BUCK circuit provided by the measurement circuit (3) out1 Adjust the duty cycle of waveform PWM1, and use the on-time of the upper bridge arm switch tube Q1 under the duty cycle as the magnetizing current duration T of the energy storage inductor L1. inj .

3. The bidirectional DC-DC conversion PWM waveform generating circuit according to claim 1, characterized in that: The single-chip computer circuit (11) comprises a PWM waveform parameter determination circuit, the PWM waveform parameter determination circuit comprises a digital operation circuit, a storage circuit and a PWM waveform oscillation circuit, the operation circuit performs a PWM waveform parameter determination operation in a BOOST mode under the control of an instruction stored in the storage circuit, specifically comprising the following operation steps: The duty cycle of the waveform PWM3 output by the PWM waveform oscillation circuit corresponding to the third output terminal of the single-chip circuit (11) is set to 1, that is, the waveform PWM3 output by the third output terminal is kept at a high level; Using the relation T ON = T con -T d1 -T △ Determine the conduction time width T of the upper bridge arm switch tube Q1 ON Value, use T ON Determine the high level time or duty cycle of the PWM waveform oscillation circuit output waveform PWM4 corresponding to the fourth output terminal of the single-chip circuit (11); wherein T △ It is T con Time correction value; T d1 is the first dead time between the upper bridge arm switch tube Q1 and the lower bridge arm switch tube Q2; Use the output voltage value V of the BOOST circuit provided by the measurement circuit (3) out2 Adjust the duty cycle of waveform PWM2, and use the on-time of the lower bridge arm switch tube Q2 under the duty cycle as the magnetizing current duration T of the energy storage inductor L1. inj .

4. The bidirectional DC-DC conversion PWM waveform generating circuit according to claim 1, characterized in that: The single-chip computer circuit (11) comprises a freewheeling time determination circuit, which comprises a digital operation circuit and a memory. In a BUCK circuit driving mode, the digital operation circuit performs the following operations under the control of a storage instruction of the memory: Using the geometric relationship (V in1 -V out1 ) / V out1 =T con / T inj Solve for the follow-up time T con The value of (V in1 -V out1 ) is the voltage across the energy storage inductor in the magnetizing state in BUCK mode, V out1 It is the voltage across the energy storage inductor in the freewheeling state, V out1 It is also the output voltage of the BUCK circuit, T con is the freewheeling time, T inj is the magnetization time.

5. The bidirectional DC-DC conversion PWM waveform generating circuit according to claim 1, characterized in that: The single-chip computer circuit (11) comprises a freewheeling time determination circuit, which comprises a digital operation circuit and a memory. In a BOOST circuit driving mode, the digital operation circuit performs the following operations under the control of a storage instruction of the memory: Using the geometric relationship V in2 / (V out2 -V in2 ) = T con / T inj Solve for the follow-up time T con The value of Among them, V in2 is the voltage across the energy storage inductor in the magnetized state in BOOST mode, (V out2 -V in2 ) is the voltage across the energy storage inductor in the freewheeling state, V out2 is the output voltage of the BOOST circuit, T con is the freewheeling time, T inj is the magnetization time.

6. The bidirectional DC-DC conversion PWM waveform generating circuit according to claim 1, characterized in that: At least one of the first AND operation circuit (12) and the second AND operation circuit (13) comprises a digital integrated circuit that performs an AND operation.

7. The bidirectional DC-DC conversion PWM waveform generating circuit according to claim 1, characterized in that: At least one of the first AND operation circuit (12) and the second AND operation circuit (13) comprises an AND operation circuit composed of discrete diodes and resistors; wherein, The first AND operation circuit (12) comprises diodes D3, D5, and a resistor R1, wherein the cathode of D3 is electrically connected to the third output terminal of the single-chip circuit (11), the cathode of D5 is electrically connected to the second output terminal of the single-chip circuit (11), the anodes of the diodes D3 and D5 electrically connected to each other are electrically connected to one end of the resistor R1, and the other end of the resistor R1 is electrically connected to a power source Vcc; The second AND operation circuit (13) comprises diodes D4, D6, and a resistor R2, wherein the cathode of D4 is electrically connected to the fourth output terminal of the single-chip circuit (11), the cathode of D6 is electrically connected to the first output terminal of the single-chip circuit (11), the anodes of the diodes D4 and D6 electrically connected to each other are electrically connected to one end of the resistor R2, and the other end of the resistor R2 is electrically connected to a power source Vcc.

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