Three-state double-inductor bidirectional converter for rapidly inhibiting pulse load power

Abstract

The invention belongs to the technical field of electronic circuits, and particularly relates to a three-state double-inductor bidirectional converter for rapidly suppressing pulse load power. The invention provides a novel three-state double-inductor bidirectional converter topology for rapidly inhibiting the pulse load power, the pulse load power can be rapidly inhibited, the bus current peak is ensured to be effectively reduced, and the system stability is further improved. Meanwhile, compared with a traditional three-state double-inductor bidirectional converter, the number of needed switching devices is reduced, the power supply density is improved, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic circuits, and in particular relates to a three-state dual-inductor bidirectional converter for rapidly suppressing pulse load power. Background Art

[0002] The output signal of a pulse load power supply generally presents a wide frequency band and pulse variation characteristics, which places higher requirements on the stability of its front-end power supply system. When the power supply system is a limited capacity system, its own regulation is difficult to respond to the change of pulse load power in time, so the power supply system will produce excessive voltage fluctuations, affecting the stability of the power supply system.

[0003] In order to reduce the impact of the strong pulse characteristics of the pulse load on the power supply system and balance the instantaneous power difference between the pulse load and the power supply system, a bidirectional converter is usually connected in parallel between the front-stage power supply system and the pulse load, and the other end of the converter is connected to the energy storage capacitor. Its topology and power flow are as follows: Figure 1 As shown. Allowable energy storage capacitor C s Voltage across the terminals v Cs Fluctuation to reduce the size of the capacitor. When overloaded, the front converter provides an average power P ave , the bidirectional DC / DC converter provides pulsating power P pul , as shown in (b); when the load is light, the front-stage converter still provides average power, and the bidirectional DC / DC converter absorbs excess power to achieve power balance, as shown in (c).

[0004] However, when the pulse load changes between light load and heavy load, the inductor current of the bidirectional DC / DC converter cannot change immediately due to its inherent characteristics and cannot respond to the change of load current immediately, resulting in the previous bus current i o There is a large current transient spike, the peak value of which is equal to the load current difference between light load and heavy load, such as Figure 2 shown.

[0005] In order to reduce the impact of current spikes on the power supply system, it is necessary to improve the transient response of the inductor current of the bidirectional DC / DC converter when the load current changes. The current transient spike phenomenon can be reduced to a certain extent by using a fast response control strategy and increasing the slope of the inductor current. However, due to the Lenz effect of the inductor, the current on it cannot change suddenly, and the control strategy cannot fundamentally eliminate the current spike.

[0006] Therefore, a three-state dual-inductor bidirectional converter topology using two inductors is used to suppress the bus current spike. Figure 3 As shown. This topology has two inductor current branches. When the circuit works in light load mode, the capacitor C s The current i is charged through the branch S3, D1, and L1, and L2 is freewheeling through S6 and D4. When the equivalent series resistance of the inductor is ignored, the current iL2 Almost unchanged; when the circuit works in heavy load mode, the capacitor C s The energy storage capacitor C is charged through the branch S5, D3, and L2, and L1 is continuously charged through S4 and D2. s Charging, the current direction of the inductor L1 is positive; the second state is the energy storage capacitor C s Discharging, the current direction of the inductor L2 is negative; the third state is that the two inductor currents flow through D2 and D4 respectively.

[0007] Existing parallel pulse load power suppression topology, bus current i o When the pulse load power jumps, a current spike will be generated due to the change in current direction. The peak value is the same as the difference between the load current under light / heavy load, which will have a certain impact on the stability of the circuit. Although the traditional three-state dual-inductor bidirectional converter topology can effectively solve this problem and suppress the transient current spike, it has many switching devices, is too large in size, and has a high cost, which is not conducive to the miniaturization and low-cost development of the power supply system. Summary of the invention

[0008] The present invention aims to quickly suppress pulse load power and improve the power density of traditional three-state dual-inductor bidirectional converters, and proposes a new three-state dual-inductor bidirectional converter topology. The main features of the present invention are: improving the response speed of the bidirectional DC / DC converter, quickly suppressing pulse load power, and ensuring effective suppression of transient spikes of bus current. On this basis, compared with the traditional three-state dual-inductor bidirectional converter, by multiplexing the inductor freewheeling circuit and the working circuit, 1 / 3 of the switching tubes and 1 / 2 of the diodes are reduced, thereby effectively reducing the size of the bidirectional converter, which is conducive to the miniaturization of the power supply system.

[0009] The technical solution of the present invention is:

[0010] A three-state dual-inductor bidirectional converter for rapidly suppressing pulse load power comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a capacitor, a first inductor, a second inductor, a first diode and a second diode; wherein one end of the first inductor and the cathode of the first diode are connected to the anode of the pulse load voltage, the anode of the first diode is connected to one end of the third switch tube, and the other end of the third switch tube is connected to the other end of the first inductor, one end of the first switch tube and one end of the second switch tube; the other end of the second switch tube is connected to one end of the capacitor, and the other end of the first switch tube is connected to the other end of the capacitor, one end of the fourth switch tube and one end of the second inductor; the other end of the fourth switch tube is connected to the anode of the second diode, and the cathode of the second diode is connected to the other end of the second inductor and the cathode of the pulse load voltage;

[0011] The enable signals of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are defined as the first switch signal, the second switch signal, the third switch signal and the fourth switch signal respectively. The four switch tubes are controlled by the four switch signals so that at any time, only one of the first inductor and the second inductor is in a working state, and the other inductor is freewheeling through the parallel switch tube and the diode to keep the inductor current value unchanged, thereby suppressing the bus current i o The current transient spike.

[0012] Furthermore, the first inductor, the first switch tube, the second switch tube and the capacitor constitute a Boost converter, and the second inductor, the first switch tube, the second switch tube and the capacitor constitute a Buck converter structure.

[0013] Furthermore, the first switch signal and the second switch signal are generated by the pulse load current passing through the driving circuit, specifically by: Cs With its reference value v Cs_ref The difference is compared and passed through the voltage loop PI circuit to obtain the voltage loop modulation wave i o_ref1 ; The load current i p The average value of the load current obtained after the second-order filter circuit is taken as the bus current i o The reference quantity i o_ref2 ; Then i o with i o_ref1 +i o_ref2 The deviation is obtained by subtracting, and the deviation is used to obtain a switch control signal through a PI link, and then a first switch signal and a second switch signal are obtained after PWM modulation;

[0014] The third switch signal and the fourth switch signal are generated by the pulse load current i p After sampling, when the pulse load is light, switch S3 is turned off and S4 is turned on; when the load is heavy, switch S3 is turned on and S4 is turned off.

[0015] The beneficial effects of the present invention are as follows: the present invention proposes a novel three-state dual-inductor bidirectional converter topology for rapidly suppressing pulse load power, which can rapidly suppress pulse load power, ensure effective reduction of bus current spikes, and thus improve system stability. At the same time, compared with the traditional three-state dual-inductor bidirectional converter, the number of required switching devices is reduced, the power supply density is increased, and the cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a parallel pulse load power suppression topology and power flow diagram, where (a) is the pulse load power suppression topology, (b) is the power flow under heavy load, and (c) is the power flow under light load.

[0017] Figure 2It is a schematic diagram of the main waveform of the current spike.

[0018] Figure 3 This is the topology diagram of the traditional three-state dual-inductor bidirectional converter.

[0019] Figure 4 It is a topology diagram of the three-state dual-inductor bidirectional converter of the present invention.

[0020] Figure 5 It is the main current waveform diagram of the three-state dual-inductor bidirectional converter of the present invention.

[0021] Figure 6 It is a schematic diagram of the working modes of the three-state dual-inductor bidirectional converter of the present invention, wherein (a) is charging working mode one, (b) is charging working mode two, (c) is discharging working mode one, and (d) is discharging working mode two.

[0022] Figure 7 It is a control principle block diagram of the three-state dual-inductor bidirectional converter of the present invention.

[0023] Figure 8 This is the topology structure and control principle block diagram of the traditional bidirectional Buck / Boost converter, where (a) is the topology structure and (b) is the control principle block diagram.

[0024] Fig. 9 is the bus current i of the traditional bidirectional Buck / Boost converter o Waveform diagram, where (a) is a 100 Hz waveform and (b) is a 500 Hz waveform.

[0025] Fig.10 These are the simulation waveforms of the three-state dual-inductor bidirectional converter, where (a) is 100Hz, 30% duty cycle, (b) is 100Hz, 50% duty cycle, (c) is 100Hz, 70% duty cycle, (d) is 500Hz, 30% duty cycle, (e) is 500Hz, 50% duty cycle, and (f) is 500Hz, 70% duty cycle. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0027] The novel three-state dual-inductor bidirectional DC / DC converter topology proposed in the present invention is as follows: Figure 4 As shown, it mainly includes a Boost converter, a Buck converter and an inductor freewheeling circuit, wherein the inductor L1 and the switch tubes S1, S2 and the energy storage capacitor C s The Boost converter structure is composed of inductor L2, switch tubes S1, S2 and energy storage capacitor C s Constitute the Buck converter structure; in the figure, v o is the voltage across the pulse load, vcs is the voltage across the energy storage capacitor, i L1 The inductor current of the bidirectional DC / DC converter when charging the energy storage capacitor, i L2 is the inductor current of the bidirectional DC / DC converter when the energy storage capacitor is discharged. Its working principle is: at any time, only one inductor in the bidirectional converter circuit is in working state, and at this time, the other inductor is freewheeling through the parallel switch tube and diode to keep the inductor current value unchanged. Through the two inductor branches, the load is light and heavy, and the bus current i is effectively suppressed. o The current transient spike, its main current waveform is as follows Figure 5 shown.

[0028] The main working modes of the three-state dual-inductor bidirectional converter topology are as follows: Figure 6 When the pulse load works in light load mode, the working mode is as follows. Figure 6 At this time, part of the energy of the front-stage power supply system is supplied to the load, and the rest of the energy is supplied to the energy storage capacitor C s Charging; switch S3 is always off, the energy storage capacitor C s The current i is charged through the inductor L1; S4 is always on, and L2 is continuous through S4 and D2. When the equivalent series resistance of the inductor is ignored, the current i L2 The freewheeling current remains almost unchanged.

[0029] When the pulse load works in heavy load mode, the working mode is as follows Figure 6 At this time, all the energy of the front-stage power supply system is supplied to the load, and the energy storage capacitor C s Discharge to the load; switch S4 is always off, capacitor C s Discharge through inductor L2; S3 is always on, L1 continues to flow through S3 and D1, and when the equivalent series resistance of the inductor is ignored, the current i L1 The freewheeling current remains almost unchanged.

[0030] The driving signals of the switches S1 and S2 are Figure 1 The pulse load current i p The voltage loop control only needs to ensure that the energy storage capacitor voltage v Cs The minimum value is higher than the previous voltage v o Ensure that the circuit works normally, the energy storage capacitor voltage v Cs With its reference value v Cs_ref The difference between the two is compared and the voltage loop PI circuit is used to obtain the voltage loop modulation wave i o_ref1 ; The current loop introduces a pulse load current i p As the control quantity, the load current i p The average value of the load current obtained after the second-order filter circuit is taken as the bus current i o The reference quantity i o_ref2; The bus current i o As the control object, i o with i o_ref1 +i o_ref2 The deviation is obtained by difference, and the deviation is used to obtain the switch control signal through the PI link, and then driven to drive the bidirectional DC / DC converter switch tubes S1 and S2 after PWM modulation.

[0031] The driving signal of the switch tubes S3 and S4 is composed of the pulse load current i p After sampling and conditioning, the pulse load is generated. When the load is light, the switch S3 is turned off and S4 is turned on. When the load is heavy, the switch S3 is turned on and S4 is turned off. The specific control principle block diagram is as follows Figure 7 shown.

[0032] Simulation Verification

[0033] A simulation platform for the novel three-state dual-inductor bidirectional converter was built based on Matlab / Simulink, and simulation experiments were carried out under the pulse load power of 100 / 500W. The specific platform simulation parameters are shown in Table 1.

[0034] Table 1 Pulse load power supply experimental platform parameters

[0035] <![CDATA[Preamplifier voltage v o > 50V <![CDATA[Energy storage capacitor C b > 470μF <![CDATA[Energy storage capacitor voltage v Cb > 100V <![CDATA[Inductor L1]]> 680μH <![CDATA[Inductor L2]]> 500μH <![CDATA[Switching frequency f s > 100kHz <![CDATA[Pulse load frequency f p > 100Hz / 500Hz Pulse duty cycle D 30％ / 50％ / 70％ Light pulse load power 100W Heavy duty pulse load power 500W

[0036] The effectiveness of the proposed new three-state dual-inductor bidirectional converter topology is verified by simulation, and the traditional bidirectional Buck / Boost converter is simulated and tested at the same time. The purpose is to o Transient spikes are compared.

[0037] The topology and control principle block diagram of the traditional bidirectional Buck / Boost converter are as follows: Figure 8 As shown in the figure, the inductor current cannot change suddenly, which generates a current spike with the same value as the load current difference under light / heavy load. The converter is simulated and tested under the conditions of pulse frequency of 100Hz and 500Hz and duty cycle of 30%, 50%, and 70%, and the bus current waveform is shown in the figure below. Fig. 9 As shown in the simulation waveform, it can be seen that the bus current peak remains at around 15A, which is close to the theoretical value of 16A.

[0038] The novel three-state dual-inductor bidirectional Buck / Boost converter topology proposed in this invention is as follows: Figure 4 As shown in the figure, the energy storage capacitor voltage v is simulated and tested under the conditions of pulse frequency of 100Hz and 500Hz and duty cycle of 30%, 50% and 70% respectively. Cs , bus current i o and the bidirectional converter inductor current i L The main circuit simulation waveforms are as follows: Fig.10 shown.

[0039] The simulation results are compared with the bus current simulation data of the traditional bidirectional Buck / Boost converter as shown in Table 2. It is easy to see from the simulation results that when the pulse frequency is 100Hz, the current transient peak is about 1 / 10 of the traditional bidirectional Buck / Boost converter, and when the pulse frequency is 500Hz, the current transient peak is about 1 / 50 of the traditional bidirectional Buck / Boost converter. The new three-state dual-inductor bidirectional converter proposed in the present invention can effectively suppress the transient peak of the bus current.

[0040] Table 2 Bus current i o Transient spike simulation data

[0041]

[0042]

[0043] Different from the traditional three-state dual-inductor bidirectional converter, the new topology structure proposed in the present invention requires fewer switching devices, and the comparison of the number of components is shown in Table 3. The newly proposed new three-state dual-inductor converter reduces 1 / 3 of the switching tubes and 1 / 2 of the diodes while maintaining the current spike suppression effect, effectively reducing the cost, improving the power density of the pulse load power suppression topology, and ensuring the stability of the power supply system.

[0044] Table 3 Comparison of the number of components

[0045]

Claims

1. A three-state dual-inductor bidirectional converter for rapidly suppressing pulse load power, characterized in that: It includes a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a capacitor, a first inductor, a second inductor, a first diode, and a second diode; wherein one end of the first inductor and the negative electrode of the first diode are connected to the positive electrode of the pulse load voltage, the positive electrode of the first diode is connected to one end of the third switch tube, and the other end of the third switch tube is connected to the other end of the first inductor, one end of the first switch tube, and one end of the second switch tube; the other end of the second switch tube is connected to one end of the capacitor, and the other end of the first switch tube is connected to the other end of the capacitor, one end of the fourth switch tube, and one end of the second inductor; the other end of the fourth switch tube is connected to the positive electrode of the second diode, and the negative electrode of the second diode is connected to the other end of the second inductor and the negative electrode of the pulse load voltage; The enable signals of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are defined as the first switch signal, the second switch signal, the third switch signal and the fourth switch signal respectively. The four switch tubes are controlled by the four switch signals so that at any time, only one of the first inductor and the second inductor is in a working state, and the other inductor is freewheeling through the parallel switch tube and the diode to keep the inductor current value unchanged, thereby suppressing the bus current i o The current transient spike.

2. A three-state dual-inductor bidirectional converter for rapidly suppressing pulse load power according to claim 1, characterized in that: The first inductor, the first switch tube, the second switch tube and the capacitor constitute a Boost converter, and the second inductor, the first switch tube, the second switch tube and the capacitor constitute a Buck converter structure.

3. The three-state dual-inductor bidirectional converter for rapidly suppressing pulse load power according to claim 1, characterized in that: The first switch signal and the second switch signal are generated by the pulse load current passing through the drive circuit. The specific method is: Cs With its reference value v Cs_ref The difference is compared and passed through the voltage loop PI circuit to obtain the voltage loop modulation wave i o_ref1 ; The load current i p The average value of the load current obtained after the second-order filter circuit is taken as the bus current i o The reference quantity i o_ref2 ; Then i o with i o_ref1 +i o_ref2 The deviation is obtained by subtracting, and the deviation is used to obtain a switch control signal through a PI link, and then a first switch signal and a second switch signal are obtained after PWM modulation; The third switch signal and the fourth switch signal are generated by the pulse load current i p After sampling, when the pulse load is light, switch S3 is turned off and S4 is turned on; when the pulse load is heavy, switch S3 is turned on and S4 is turned off.

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