Vehicle-mounted charger, power factor correction circuit and controller thereof, control method

Abstract

This invention discloses an on-board charger, a power factor correction circuit, its controller, and a control method. The power factor correction circuit control method includes the following steps: determining the normally open sequence of the bridge arm switches based on the phase of the AC power supply; controlling the four bridge arm switches in the bridge circuit to be normally open sequentially according to the normally open sequence; and when the upper or lower bridge arm switch in one bridge arm circuit is normally open, controlling the upper and lower bridge arm switches in another bridge arm circuit to alternately open at a high frequency. Because this invention evenly maintains the normally open state among multiple bridge arm switches, the bridge arm switches of two bridge arms operate at alternating high frequencies, thus uniformly distributing the operating temperature of the bridge arm switches in both bridge arms and improving the stability and reliability of the circuit operation.

Description

Technical Field

[0001] This invention relates to the field of charging technology, and in particular to an on-board charger, a power factor correction circuit and its controller and control method. Background Technology

[0002] PFC stands for Power Factor Correction. The power factor refers to the relationship between effective power and total power consumption (apparent power), which is the ratio of effective power to total power consumption (apparent power). Essentially, the power factor measures the degree to which electricity is used effectively; a higher power factor indicates higher power utilization.

[0003] A power factor correction circuit may include an input capacitor unit, a high-frequency bridge arm, and a low-frequency bridge arm. The low-frequency bridge arm typically operates at a frequency of 45 Hz to 65 Hz, which is the power frequency, while the high-frequency bridge arm operates at a much higher frequency, such as between 10,000 Hz and 100,000 Hz. This results in high switching losses and high operating temperatures for the high-frequency bridge arm. Summary of the Invention

[0004] The main objective of this invention is to provide a power factor correction circuit that aims to reduce the switching losses and operating temperature of the power factor correction circuit.

[0005] To achieve the above objectives, this invention proposes a power factor correction circuit control method, applied to a power factor correction circuit, wherein the power factor correction circuit includes a bridge circuit and an AC power input terminal, and the power factor correction circuit control method includes:

[0006] Obtain the phase of the AC power supply;

[0007] The normally open sequence of the bridge arm switches is determined based on the phase of the AC power supply.

[0008] The four bridge arm switches in the bridge circuit are controlled to be normally open in sequence according to the normally open order; and when the upper or lower bridge arm switch in the same bridge arm circuit is normally open, the upper and lower bridge arm switches in the other bridge arm circuit are controlled to be alternately opened at a preset frequency; wherein, the preset frequency is greater than the frequency of the AC power supply.

[0009] In one embodiment, the step of determining the normally open sequence of the bridge arm switches based on the phase of the AC power supply includes:

[0010] The phase of the AC power supply determines whether the AC power supply is in the positive or negative half-cycle.

[0011] When it is determined that the AC power supply is in the positive half-cycle, the normally on sequence is determined as follows:

[0012] The upper bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, and the upper bridge arm switch of the second bridge arm circuit; or,

[0013] The upper bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, and the lower bridge arm switch of the first bridge arm circuit; or,

[0014] The lower bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, and the upper bridge arm switch of the second bridge arm circuit; or,

[0015] The lower bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, and the lower bridge arm switch of the first bridge arm circuit.

[0016] In one embodiment, after the step of determining whether the AC power supply is in a positive or negative half-cycle based on the phase of the AC power supply, the following step is further included:

[0017] When it is determined that the AC power supply is in the negative half-cycle, the normally-on sequence is determined as follows:

[0018] The lower bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, and the upper bridge arm switch of the first bridge arm circuit; or,

[0019] The lower bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, and the lower bridge arm switch of the second bridge arm circuit; or,

[0020] The upper bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, and the upper bridge arm switch of the first bridge arm circuit; or,

[0021] The upper bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, and the lower bridge arm switch of the second bridge arm circuit.

[0022] The present invention also proposes a power factor correction circuit controller, which includes a memory, a processor, and a power factor correction circuit control program stored in the memory and executable on the processor. When the power factor correction circuit control program is executed by the processor, it implements the steps of the power factor correction circuit control method described above.

[0023] In one embodiment, the power factor correction circuit controller includes:

[0024] The first controller is used to detect the phase of the AC power supply, determine the normally open sequence, and output the corresponding normally open sequence control signal.

[0025] The second controller has its input terminal connected to the output terminal of the first controller, and its output terminal connected to the controlled terminals of the four bridge arm switches in the bridge circuit; the second controller is used for:

[0026] The obtained AC power supply voltage, power factor correction inductor current, power factor correction circuit output voltage, and reference voltage of the output voltage;

[0027] According to the normally open sequence control signal, the four bridge arm switches in the bridge circuit are controlled to be normally open in sequence; and when the upper or lower bridge arm switch in the same bridge arm circuit is normally open, the upper and lower bridge arm switches in the other bridge arm circuit are controlled to be alternately opened at a preset frequency according to the AC power supply voltage, the power factor correction inductor current, the output voltage of the power factor correction circuit, and the reference voltage of the output voltage; wherein, the preset frequency is greater than the frequency of the AC power supply.

[0028] The present invention also proposes a power factor correction circuit, the power factor correction circuit comprising:

[0029] An inductor input unit has a first output terminal and a second output terminal. The inductor input unit is used to connect to an AC power source and store energy according to the AC power source.

[0030] A bridge circuit includes a first bridge arm circuit and a second bridge arm circuit connected in parallel at a first connection point and a second connection point. The first bridge arm circuit includes an upper bridge arm switch and a lower bridge arm switch connected in series. The common terminal of the upper and lower bridge arm switches of the first bridge arm circuit is connected to the first output terminal of the inductor input unit. The second bridge arm circuit includes an upper bridge arm switch and a lower bridge arm switch connected in series. The common terminal of the upper and lower bridge arm switches of the second bridge arm circuit is connected to the second output terminal of the inductor input unit.

[0031] The aforementioned power factor correction circuit controller is connected to the controlled terminals of each of the four bridge arm switches.

[0032] In one embodiment, one or more of the four bridge arm switches in the bridge circuit include a switching transistor and a diode;

[0033] The first end of the switching transistor is connected to the anode of the diode, and the second end of the switching transistor is connected to the cathode of the diode.

[0034] The controlled terminal of the switching transistor is the controlled terminal of the bridge arm switch, the common terminal of the first terminal of the switching transistor and the anode of the diode is the first lead terminal of the bridge arm switch, and the second terminal of the switching transistor and the cathode of the diode are the second lead terminal of the bridge arm switch.

[0035] In one embodiment, the inductive input unit includes a first inductor, one end of which is connected to the common terminal of the upper bridge arm switch and the lower bridge arm switch of the first bridge arm circuit, and the other end of which is connected to the live wire of the AC power supply.

[0036] Alternatively, the inductor input unit includes a second inductor and a third inductor. One end of the second inductor is connected to the common terminal of the upper and lower bridge arm switches of the first bridge arm circuit, and the other end of the second inductor is connected to the live wire of the AC power supply. One end of the third inductor is connected to the common terminal of the upper and lower bridge arm switches of the second bridge arm circuit, and the other end of the third inductor is connected to the neutral wire of the AC power supply.

[0037] Alternatively, the inductive input unit includes a fourth inductor, the fourth inductor including a magnetic core and a first coil and a second coil wound on the magnetic core; one end of the first coil is connected to the common terminal of the upper and lower bridge arm switches of the first bridge arm circuit, and the other end of the first coil is connected to the live wire of the AC power supply; one end of the second coil is connected to the common terminal of the upper and lower bridge arm switches of the second bridge arm circuit, and the other end of the second coil is connected to the neutral wire of the AC power supply.

[0038] In one embodiment, the inductor input unit further includes:

[0039] An electromagnetic interference filter is provided, wherein the input terminal of the electromagnetic interference filter is connected to the AC power supply, and the electromagnetic interference filter is used to filter the AC power supply before outputting it.

[0040] The present invention also proposes an on-board charger, which includes a DC-DC converter circuit and the aforementioned power factor correction circuit; wherein the DC-DC converter circuit is connected to the power factor correction circuit.

[0041] This invention controls the four bridge arm switches in a bridge circuit to turn on sequentially according to a preset normally open sequence. When one upper or lower bridge arm switch in the same bridge arm circuit is normally open, the upper and lower bridge arm switches in the other bridge arm circuit are controlled to turn on alternately at a preset frequency. Thus, when the bridge arm switch in the first bridge arm circuit is normally open, the second bridge arm circuit performs high-frequency chopping; when the bridge arm switch in the second bridge arm circuit is normally open, the first bridge arm circuit performs high-frequency chopping. In other words, the first and second bridge arm circuits alternate as high-frequency bridge arms for high-frequency chopping, thereby distributing the switching losses from the two bridge arm switches on one bridge arm to all four bridge arm switches across two bridge arms. This effectively balances switching losses, reduces the losses of individual bridge arm switches, and makes the operating temperature of the four bridge arm switches in the bridge circuit more uniform. This, in turn, reduces the overall thermal stress of the power factor correction circuit and greatly improves the stability of the power factor correction circuit. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0043] Figure 1 This is a circuit diagram of an embodiment of the power factor correction circuit of the present invention;

[0044] Figure 2 This is a flowchart of an embodiment of the power factor correction circuit control method of the present invention;

[0045] Figure 3 This is a waveform diagram of key nodes in an embodiment of the power factor correction circuit of the present invention;

[0046] Figure 4 This is a flowchart of another embodiment of the power factor correction circuit control method of the present invention;

[0047] Figure 5 This is a circuit diagram of an embodiment of the power factor correction circuit controller of the present invention;

[0048] Figure 6 This is a flowchart illustrating the operation of an embodiment of the second controller of the power factor correction circuit controller of the present invention.

[0049] Explanation of icon numbers:

[0050]

[0051]

[0052] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0054] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0055] This invention proposes a power factor correction circuit control method, which is applied to a power factor correction circuit.

[0056] In one embodiment, reference is made to Figure 1 The power correction circuit includes an AC power supply (VAC) input terminal, an inductor input unit 30, a bridge circuit 40, and a power factor correction circuit controller (not shown in the figure) connected in sequence to control the operation of the bridge circuit. The AC power supply (VAC) input terminal can be connected to the neutral wire (N) and the live wire (L) of the AC power supply (VAC). The bridge circuit 40 includes at least a first bridge arm circuit and a second bridge arm circuit. The first bridge arm circuit includes an upper bridge arm switch Q1 and a lower bridge arm switch Q2, and the second bridge arm circuit includes an upper bridge arm switch Q3 and a lower bridge arm switch Q4.

[0057] Reference Figure 2 The power factor correction circuit control method includes:

[0058] S100, Obtain the phase of the AC power supply VAC;

[0059] Phase detection can be achieved by setting up phase detection circuit 12 in the power factor correction circuit, or it can be acquired by other devices and output to the power factor correction circuit.

[0060] S200. Determine the normally open sequence of the bridge arm switches according to the phase of the AC power supply VAC;

[0061] This embodiment can determine whether the AC power supply VAC is in the positive or negative half-cycle based on its phase according to the power factor correction circuit. It then selects the corresponding normally open sequence for each half-cycle to avoid phase mismatch between the normally open bridge arm switch and the AC power supply VAC, which could damage the power factor correction circuit or prevent it from performing power factor correction. It is worth noting that in this embodiment, the phase of the AC power supply VAC is determined by the voltage between the live wire L and the neutral wire N. The method is similar when using the voltage between the neutral wire N and the live wire L, and will not be elaborated here.

[0062] S300. Control the four bridge arm switches in the bridge circuit to be normally open in sequence according to the normally open order; and when the upper or lower bridge arm switch in the same bridge arm circuit is normally open, control the upper and lower bridge arm switches in the other bridge arm circuit to be alternately opened at a preset frequency to achieve power factor correction; wherein, the preset frequency is greater than the frequency of the AC power supply VAC.

[0063] The preset frequency is the high-frequency frequency, which can be between 10,000 Hz and 100,000 Hz to achieve high-frequency chopping operation. The frequency of the AC power supply (VAC) is the low-frequency frequency, which can be between 45 Hz and 65 Hz, i.e., the power frequency. When the bridge arm operates at the low-frequency frequency, the opening time of its bridge arm switch is much longer than when operating at the high-frequency frequency; therefore, this is referred to as the normally open state of the bridge arm switch.

[0064] Controlling the four bridge arm switches to be normally open sequentially can be achieved by controlling them to be normally open sequentially within two cycles of the AC power supply (VAC). In other embodiments, the four bridge arm switches can also be controlled to be normally open sequentially within multiple cycles. For example, two bridge arm switches, such as bridge arm switches Q1 and Q2, may be normally open alternately in the current two consecutive cycles, while another two bridge arm switches, such as bridge arm switches Q3 and Q4, may be normally open alternately in the next two consecutive cycles.

[0065] Figure 3 The diagram illustrates, in one embodiment, the current waveforms q1, q2, q3, and the magnitude of the current flowing through the four bridge arm switches Q1 to Q4. This diagram uses an example where the normally open sequence is: upper bridge arm switch Q1 of the first bridge arm circuit, lower bridge arm switch Q2 of the first bridge arm circuit, lower bridge arm switch Q4 of the second bridge arm circuit, and upper bridge arm switch Q3 of the second bridge arm circuit. From... Figure 3It can be seen that the current flowing through each bridge arm switch varies periodically, rather than being a continuous large current. This balances the current flowing through the four bridge arm switches, effectively reducing switching losses. T1 and T2 represent two consecutive cycles of the AC power supply VAC.

[0066] This invention controls the four bridge arm switches in a bridge circuit to turn on sequentially according to a preset normally open sequence. When one upper or lower bridge arm switch in the same bridge arm circuit is normally open, the upper and lower bridge arm switches in the other bridge arm circuit are controlled to turn on alternately at a preset frequency. Thus, when the bridge arm switch in the first bridge arm circuit is normally open, the second bridge arm circuit performs high-frequency chopping; when the bridge arm switch in the second bridge arm circuit is normally open, the first bridge arm circuit performs high-frequency chopping. In other words, the first and second bridge arm circuits alternate as high-frequency bridge arms for high-frequency chopping, thereby distributing the switching losses from the two bridge arm switches on one bridge arm to all four bridge arm switches across two bridge arms. This effectively balances switching losses, reduces the losses of individual bridge arm switches, and makes the operating temperature of the four bridge arm switches in the bridge circuit more uniform. This, in turn, reduces the overall thermal stress of the power factor correction circuit and greatly improves the stability of the power factor correction circuit.

[0067] Reference Figure 4 In one embodiment, the step of determining the normally open sequence of the bridge arm switches based on the phase of the AC power supply VAC includes:

[0068] S201. Determine whether the AC power supply VAC is in the positive half-cycle or the negative half-cycle based on the phase of the AC power supply VAC.

[0069] When the phase of the AC power supply VAC is between 0° and 180°, it is determined that the AC power supply VAC is in the positive half-cycle. When the phase of the AC power supply VAC is between 180° and 360°, it is determined that the AC power supply VAC is in the negative half-cycle of a cycle. Alternatively, the zero-crossing point of the AC power supply VAC could be detected first, followed by the phase detection. When the phase of the AC power supply VAC is determined to be 0°, it is determined to be in the positive half-cycle; when the phase of the AC power supply VAC is determined to be 180°, it is determined to be in the negative half-cycle of a cycle. Performing zero-crossing detection first ensures that the normally open switch can complete a full positive or negative half-cycle in subsequent steps.

[0070] S202. When it is determined that the AC power supply VAC is in the positive half-cycle, the normally open sequence is determined to be: upper bridge arm switch Q1 of the first bridge arm circuit, lower bridge arm switch Q2 of the first bridge arm circuit, lower bridge arm switch Q4 of the second bridge arm circuit, and upper bridge arm switch Q3 of the second bridge arm circuit; or, upper bridge arm switch Q1 of the first bridge arm circuit, upper bridge arm switch Q3 of the second bridge arm circuit, lower bridge arm switch Q4 of the second bridge arm circuit, and lower bridge arm switch Q2 of the first bridge arm circuit; or, lower bridge arm switch Q4 of the second bridge arm circuit, lower bridge arm switch Q2 of the first bridge arm circuit, upper bridge arm switch Q1 of the first bridge arm circuit, and upper bridge arm switch Q3 of the second bridge arm circuit; or, lower bridge arm switch Q4 of the second bridge arm circuit, upper bridge arm switch Q3 of the second bridge arm circuit, upper bridge arm switch Q1 of the first bridge arm circuit, and lower bridge arm switch Q2 of the first bridge arm circuit.

[0071] Reference Figure 1 When the AC power supply VAC is in the positive half-cycle, this embodiment controls the normally open switch to be either the upper bridge arm switch Q1 of the first bridge arm circuit or the lower bridge arm switch Q4 of the second bridge arm circuit to ensure the stable operation of the bridgeless power factor correction circuit. The following is a brief description of the circuit's operation, using the normally open switch Q1 of the first bridge arm circuit as an example. When the upper bridge arm switch Q1 of the first bridge arm circuit is normally open, the two bridge arm switches of the second bridge arm circuit alternately open at a high frequency. When the upper bridge arm switch Q3 of the second bridge arm circuit is open and the lower bridge arm switch Q4 is open, the AC power supply VAC, the inductor input unit 30, the upper bridge arm switch Q1 of the first bridge arm circuit, and the upper bridge arm switch Q3 of the second bridge arm circuit form a loop. The AC power supply VAC charges the power factor correction inductor L1 in the inductor input unit 30, and the output capacitor C1 supplies power to the load. When the lower bridge arm switch Q4 of the second bridge arm circuit is open, the upper bridge arm switch Q3 of the second bridge arm circuit is open. At this point, the AC power supply VAC, the inductor input unit 30, the upper bridge arm switch Q1 of the first bridge arm circuit, the load / output capacitor C1, and the lower bridge arm switch Q4 of the second bridge arm circuit form a loop. The AC power supply VAC and the power factor correction inductor L1 in the inductor input unit 30 simultaneously supply power to the load, thus completing one operation of the power factor correction circuit. When the normally open switch is the lower bridge arm switch Q4 of the second bridge arm circuit, the principle is similar, and will not be elaborated here.

[0072] S203. When it is determined that the AC power supply VAC is in the negative half-cycle, the normally open sequence is determined to be: lower bridge arm switch Q2 of the first bridge arm circuit, lower bridge arm switch Q4 of the second bridge arm circuit, upper bridge arm switch Q3 of the second bridge arm circuit, and upper bridge arm switch Q1 of the first bridge arm circuit; or, lower bridge arm switch Q2 of the first bridge arm circuit, upper bridge arm switch Q1 of the first bridge arm circuit, upper bridge arm switch Q3 of the second bridge arm circuit, and lower bridge arm switch Q4 of the second bridge arm circuit; or, upper bridge arm switch Q3 of the second bridge arm circuit, lower bridge arm switch Q4 of the second bridge arm circuit, lower bridge arm switch Q2 of the first bridge arm circuit, and upper bridge arm switch Q1 of the first bridge arm circuit; or, upper bridge arm switch Q3 of the second bridge arm circuit, upper bridge arm switch Q1 of the first bridge arm circuit, lower bridge arm switch Q2 of the first bridge arm circuit, and lower bridge arm switch Q4 of the second bridge arm circuit.

[0073] Reference Figure 1 When the AC power supply VAC is in the negative half cycle, the normally open switch in this embodiment is either the lower bridge arm switch Q2 of the first bridge arm circuit or the upper bridge arm switch Q3 of the second bridge arm circuit, to ensure that the bridgeless power factor correction circuit can work stably.

[0074] It is worth noting that the normal opening sequence is as follows: upper bridge arm switch Q1 of the first bridge arm circuit, upper bridge arm switch Q3 of the second bridge arm circuit, lower bridge arm switch Q4 of the second bridge arm circuit, and lower bridge arm switch Q2 of the first bridge arm circuit; or, lower bridge arm switch Q4 of the second bridge arm circuit, lower bridge arm switch Q2 of the first bridge arm circuit, upper bridge arm switch Q1 of the first bridge arm circuit, and upper bridge arm switch Q3 of the second bridge arm circuit; or, lower bridge arm switch Q2 of the first bridge arm circuit, lower bridge arm switch Q4 of the second bridge arm circuit, upper bridge arm switch Q3 of the second bridge arm circuit, and upper bridge arm switch Q1 of the first bridge arm circuit; or, upper bridge arm switch Q3 of the second bridge arm circuit, upper bridge arm switch Q1 of the first bridge arm circuit, lower bridge arm switch Q2 of the first bridge arm circuit, and lower bridge arm switch Q4 of the second bridge arm circuit.

[0075] Within each cycle of the AC power supply VAC, the normally open bridge arm switches appear sequentially on the first bridge arm circuit and the second bridge arm circuit. That is, the first bridge arm circuit and the second bridge arm circuit alternately chop once within each cycle of the AC power supply VAC, which increases the frequency of the first bridge arm circuit and the second bridge arm circuit switching and alternating chopping, avoids one bridge arm circuit from continuously chopping for a long time, and makes the temperature of the four bridge arm switches on the two bridge arms more uniform.

[0076] The present invention also proposes a power factor correction circuit controller.

[0077] Reference Figure 5In one embodiment, the power factor correction circuit controller includes a memory, a processor, and a power factor correction circuit control program stored in the memory and executable on the processor. When the power factor correction circuit control program is executed by the processor, it implements the steps of the power factor correction circuit control method described above. The processor may be a microprocessor such as a CPU, MCU, single-chip microcomputer, DSP, or FPGA.

[0078] Reference Figure 5 In one embodiment, the power factor correction circuit controller includes a first controller 1 and a second controller 2. The first controller 1 is used to detect the phase of the AC power supply VAC, determine the normally open sequence, and output a corresponding normally open sequence control signal to the second controller 2. The output terminal of the second controller 2 is connected to the controlled terminals of the four bridge arm switches in the bridge circuit.

[0079] The first controller 1 may include an input voltage sampling circuit 11, a phase detection circuit 12, and a normally-on sequence controller 13. The specific connection relationship of each component is as follows: Figure 5 As shown. Voltage sampling circuit 11 is used to sample the voltage of AC power supply VAC, phase detection circuit 12 is used to detect the phase of AC power supply VAC, and normally open sequence controller 13 can pre-store the correspondence between normally open sequence control signals and AC power supply VAC, so that when it is determined that AC power supply VAC is in the positive half cycle or the negative half cycle, the corresponding normally open sequence control signal is output.

[0080] The second controller 2 may include an output voltage sampling circuit 21, a first error amplifier 22, a proportional-integral (PI) controller, a multiplier 24, a second error amplifier 25, a first PFC modulator 26, a first dead-time control circuit 27, a second PFC modulation circuit, a second dead-time control circuit 29, and a current sampling circuit 210. The specific connection relationships of each component are as follows: Figure 5 As shown.

[0081] The output voltage sampling circuit 21 samples the output voltage VOUT output to the load. The first error amplifier 22 calculates the error between the output voltage VOUT and the reference voltage VREF, amplifies it, and outputs a corresponding error amplification signal. The integral proportional controller 23 outputs a corresponding control quantity based on the error amplification signal output by the first error amplifier 22. At this time, the control quantity is related to the output voltage VOUT. The multiplier 24 multiplies the control quantity corresponding to the error amplification signal with the AC power supply VAC voltage. The output signal of the multiplier 24 is related to the AC power supply VAC voltage and the output voltage VOUT. The output signal of the multiplier 24 is used as the current reference signal for the power factor correction inductor current IL and output to the second error amplifier 25, so that the power factor correction inductor current IL changes with the AC power supply VAC voltage and the output voltage VOUT.

[0082] In this way, the first PFC modulator 26 and the second PFC modulator 28 can first output a low-frequency PWM signal according to the normally open sequence control signal to control the four bridge arm switches to be normally open in sequence, reducing switching losses. Then, according to the output signal of the second error amplifier 25, a high-frequency PWM signal is output to control the upper and lower bridge arm switches in the other bridge arm circuit to be opened alternately at a preset frequency, thereby achieving power factor correction. The first dead-time control circuit 27 and the second dead-time control circuit 29 can prevent two bridge arm switches in the same bridge arm circuit from being in a simultaneous open state due to switching speed issues, which would increase the load, especially when the current is too large, which could easily cause short circuits and damage to the equipment.

[0083] Specific reference Figure 6 The working steps of the second controller 2 are as follows:

[0084] S400. According to the normally open sequence control signal, control the upper bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, and the lower bridge arm switch of the second bridge arm circuit to be normally open in sequence according to the normally open sequence.

[0085] S500, the obtained AC power supply VAC voltage, power factor correction inductor current, output voltage VOUT, and output voltage reference voltage VREF.

[0086] S600: Control the four bridge arm switches in the bridge circuit to be normally open in sequence according to the normally open order; and when the upper or lower bridge arm switch in the same bridge arm circuit is normally open, control the upper and lower bridge arm switches in another bridge arm circuit to alternately open according to a preset frequency based on the voltage of the AC power supply VAC, the power factor correction inductor current, the output voltage VOUT, and the reference voltage VREF of the output voltage; wherein, the preset frequency is greater than the frequency of the AC power supply VAC.

[0087] Reference Figure 1 This invention also proposes a power factor correction circuit. The power factor correction circuit includes an inductor input unit 30, a bridge circuit, and the aforementioned power factor correction circuit controller. The specific structure of this power factor correction circuit controller is as described in the above embodiments. Since this power factor correction circuit adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here. The output terminal of the power factor correction circuit is connected to the input terminal of the DC-DC converter circuit.

[0088] The inductor input unit 30 has a first output terminal and a second output terminal. The inductor input unit 30 is used to connect to an AC power supply VAC and store energy according to the AC power supply VAC. The bridge circuit includes a first bridge arm circuit and a second bridge arm circuit connected in parallel at the first connection point A and the second connection point B. The first bridge arm circuit includes an upper bridge arm switch and a lower bridge arm switch connected in series. The common terminal of the upper bridge arm switch and the lower bridge arm switch of the first bridge arm circuit is connected to the first output terminal of the inductor input unit 30. The second bridge arm circuit includes an upper bridge arm switch and a lower bridge arm switch connected in series. The common terminal of the upper bridge arm switch and the lower bridge arm switch of the second bridge arm circuit is connected to the second output terminal of the inductor input unit 30. The power factor correction circuit controller is connected to the controlled terminals of the four bridge arm switches one by one.

[0089] Reference Figure 1 The inductor input unit 30 may include an electromagnetic interference filter 4031 (EMI filter 31) for filtering out electromagnetic interference (EMI) noise from the AC power supply VAC, and a power factor correction inductor L1 for forming a power factor correction circuit together with the first bridge arm circuit and the second bridge arm circuit. The bridge circuit may include a first bridge arm circuit and a second bridge arm circuit. In other embodiments, the bridge circuit may also include a third bridge arm for power factor correction of the three-phase AC power supply VAC. The electromagnetic interference filter 4031 may include a first input terminal, a second input terminal, a first output terminal, and a second output terminal. Its first input terminal is connected to the live wire L of the AC power supply VAC, its second input terminal is connected to the neutral wire N of the AC power supply VAC, its first output terminal is connected to the first bridge arm circuit, and its second output terminal is connected to the second bridge arm circuit. The electromagnetic interference filter 4031 can filter out electromagnetic interference noise from the AC power supply VAC, improving the stability of the power factor correction circuit.

[0090] Reference Figure 1In one embodiment, one or more of the four bridge arm switches Q1 to Q4 in the bridge circuit include switching transistors and diodes.

[0091] The first end of the switching transistor is connected to the anode of the diode, and the second end of the switching transistor is connected to the cathode of the diode; the controlled end of the switching transistor is the controlled end of the bridge arm switch, the common end of the first end of the switching transistor and the anode of the diode is the first lead end of the bridge arm switch, and the second end of the switching transistor is connected to the cathode of the diode and the second lead end of the bridge arm switch.

[0092] The switching transistor can be one or a combination of transistors, MOSFETs, or IGBTs. The diodes can be those used in parallel, such as SiC diodes and fast recovery diodes, or diodes without reverse recovery, such as GaN diodes, to further improve the stability of the power factor correction circuit.

[0093] The parallel connection of the switching transistor and the diode in this embodiment can solve the problem of the switching transistor's turn-on delay and the loss problem caused by the diode's voltage drop.

[0094] Reference Figure 1 In one embodiment, the inductor input unit 30 includes a first inductor. One end of the first inductor is connected to the common terminal of the upper bridge arm switch Q1 and the lower bridge arm switch Q2 of the first bridge arm circuit, and the other end of the first inductor is connected to the live wire L of the AC power supply VAC. The first inductor, which is also the power factor correction inductor L1 of the inductor input unit 30, is used to combine the first bridge arm circuit and the second bridge arm circuit to form a power factor correction circuit.

[0095] In some embodiments, the inductor input unit 30 includes a second inductor and a third inductor (not shown in the figure). One end of the second inductor is connected to the common terminal of the upper and lower bridge arm switches of the first bridge arm circuit, and the other end of the second inductor is connected to the live wire L of the AC power supply VAC. One end of the third inductor is connected to the common terminal of the upper and lower bridge arm switches of the second bridge arm circuit, and the other end of the third inductor is connected to the neutral wire N of the AC power supply VAC. By adding a third inductor between the neutral wire N and the second bridge arm circuit, the power factor correction circuit is made symmetrical, avoiding common-mode electromagnetic compatibility (EMC) problems caused by high-frequency voltage fluctuations between the live wire L and the neutral wire N of the AC power supply VAC during the negative half-cycle.

[0096] Alternatively, the inductor input unit 30 may include a fourth inductor (not shown in the figure); the fourth inductor includes a magnetic core, and a first coil and a second coil wound on the magnetic core; one end of the first coil is connected to the common terminal of the upper bridge arm switch Q1 and the lower bridge arm switch Q2 of the first bridge arm circuit, and the other end of the first coil is connected to the live wire L of the AC power supply VAC; one end of the second coil is connected to the common terminal of the upper bridge arm switch Q3 and the lower bridge arm switch Q4 of the second bridge arm circuit, and the other end of the second coil is connected to the neutral wire N of the AC power supply VAC. The fourth inductor may be a differential-mode inductor, which can not only cooperate with the first and second bridge arm circuits to achieve power factor correction, but also filter out differential-mode noise in the AC power supply VAC.

[0097] This invention also proposes an on-board charger, which includes a DC-DC converter circuit and the aforementioned power factor correction circuit. The specific structure of the power factor correction circuit is as described in the above embodiments. Since this on-board charger adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here. The output terminal of the power factor correction circuit is connected to the input terminal of the DC-DC converter circuit.

[0098] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A power factor correction circuit control method, applied to a power factor correction circuit, wherein the power factor correction circuit includes a bridge circuit and an AC power input terminal, characterized in that, The power factor correction circuit control method includes: Obtain the phase of the AC power supply; The normally open sequence of the bridge arm switches is determined based on the phase of the AC power supply. The four bridge arm switches in the bridge circuit are controlled to be normally open in sequence according to the normally open order; and when the upper or lower bridge arm switch in the same bridge arm circuit is normally open, the upper and lower bridge arm switches in the other bridge arm circuit are controlled to be alternately opened at a preset frequency; wherein, the preset frequency is greater than the frequency of the AC power supply. The normally open sequence is used to enable the two bridge arm circuits formed by the four bridge arm switches to alternately and independently perform high-frequency chopping operation in order to balance the switching losses of the four bridge arm switches. The step of determining the normally open sequence of the bridge arm switches based on the phase of the AC power supply includes: The phase of the AC power supply determines whether the AC power supply is in the positive or negative half-cycle. When it is determined that the AC power supply is in the positive half-cycle, the normally on sequence is determined as follows: The upper bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, and the upper bridge arm switch of the second bridge arm circuit; or, The upper bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, and the lower bridge arm switch of the first bridge arm circuit; or, The lower bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, and the upper bridge arm switch of the second bridge arm circuit; or, The lower bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, and the lower bridge arm switch of the first bridge arm circuit. After the step of determining whether the AC power supply is in the positive or negative half-cycle based on the phase of the AC power supply, the following step is also included: When it is determined that the AC power supply is in the negative half-cycle, the normally-on sequence is determined as follows: The lower bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, and the upper bridge arm switch of the first bridge arm circuit; or, The lower bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, the upper bridge arm switch of the second bridge arm circuit, and the lower bridge arm switch of the second bridge arm circuit; or, The upper bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the second bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, and the upper bridge arm switch of the first bridge arm circuit; or, The upper bridge arm switch of the second bridge arm circuit, the upper bridge arm switch of the first bridge arm circuit, the lower bridge arm switch of the first bridge arm circuit, and the lower bridge arm switch of the second bridge arm circuit.

2. A power factor correction circuit controller, characterized in that, The power factor correction circuit controller includes a memory, a processor, and a power factor correction circuit control program stored in the memory and executable on the processor. When the power factor correction circuit control program is executed by the processor, it implements the steps of the power factor correction circuit control method as described in claim 1.

3. The power factor correction circuit controller as described in claim 2, characterized in that, The power factor correction circuit controller includes: The first controller is used to detect the phase of the AC power supply, determine the normally open sequence, and output the corresponding normally open sequence control signal. The second controller has its input terminal connected to the output terminal of the first controller, and its output terminal connected to the controlled terminals of the four bridge arm switches in the bridge circuit; the second controller is used for: The obtained AC power supply voltage, power factor correction inductor current, power factor correction circuit output voltage, and reference voltage of the output voltage; According to the normally open sequence control signal, the four bridge arm switches in the bridge circuit are controlled to be normally open in sequence; and when the upper or lower bridge arm switch in the same bridge arm circuit is normally open, the upper and lower bridge arm switches in the other bridge arm circuit are controlled to be alternately opened at a preset frequency according to the AC power supply voltage, the power factor correction inductor current, the output voltage of the power factor correction circuit, and the reference voltage of the output voltage; wherein, the preset frequency is greater than the frequency of the AC power supply.

4. A power factor correction circuit, characterized in that, The power factor correction circuit includes: An inductor input unit has a first output terminal and a second output terminal. The inductor input unit is used to connect to an AC power source and store energy according to the AC power source. A bridge circuit includes a first bridge arm circuit and a second bridge arm circuit connected in parallel at a first connection point and a second connection point. The first bridge arm circuit includes an upper bridge arm switch and a lower bridge arm switch connected in series. The common terminal of the upper and lower bridge arm switches of the first bridge arm circuit is connected to the first output terminal of the inductor input unit. The second bridge arm circuit includes an upper bridge arm switch and a lower bridge arm switch connected in series. The common terminal of the upper and lower bridge arm switches of the second bridge arm circuit is connected to the second output terminal of the inductor input unit. The power factor correction circuit controller as described in any one of claims 2 to 3, wherein the power factor correction circuit controller is connected to the controlled terminals of each of the four bridge arm switches.

5. The power factor correction circuit as described in claim 4, characterized in that, One or more of the four bridge arm switches in the bridge circuit include a switching transistor and a diode; The first end of the switching transistor is connected to the anode of the diode, and the second end of the switching transistor is connected to the cathode of the diode. The controlled terminal of the switching transistor is the controlled terminal of the bridge arm switch, the common terminal of the first terminal of the switching transistor and the anode of the diode is the first lead terminal of the bridge arm switch, and the second terminal of the switching transistor and the cathode of the diode are the second lead terminal of the bridge arm switch.

6. The power factor correction circuit as described in claim 5, characterized in that, The inductor input unit includes a first inductor, one end of which is connected to the common terminal of the upper bridge arm switch and the lower bridge arm switch of the first bridge arm circuit, and the other end of which is connected to the live wire of the AC power supply. Alternatively, the inductor input unit includes a second inductor and a third inductor. One end of the second inductor is connected to the common terminal of the upper and lower bridge arm switches of the first bridge arm circuit, and the other end of the second inductor is connected to the live wire of the AC power supply. One end of the third inductor is connected to the common terminal of the upper and lower bridge arm switches of the second bridge arm circuit, and the other end of the third inductor is connected to the neutral wire of the AC power supply. Alternatively, the inductive input unit includes a fourth inductor, the fourth inductor including a magnetic core and a first coil and a second coil wound on the magnetic core; one end of the first coil is connected to the common terminal of the upper and lower bridge arm switches of the first bridge arm circuit, and the other end of the first coil is connected to the live wire of the AC power supply; one end of the second coil is connected to the common terminal of the upper and lower bridge arm switches of the second bridge arm circuit, and the other end of the second coil is connected to the neutral wire of the AC power supply.

7. The power factor correction circuit as described in any one of claims 4 to 6, characterized in that, The inductor input unit further includes: An electromagnetic interference filter is provided, wherein the input terminal of the electromagnetic interference filter is connected to an AC power supply, and the electromagnetic interference filter is used to filter the AC power supply before outputting it.

8. An on-board charger, characterized in that, The on-board charger includes a power factor correction circuit and a DC-DC converter as described in any one of claims 4 to 6; wherein the DC-DC converter is connected to the power factor correction circuit.

Images