A servo DC-DC converter topology for intelligent robots

Abstract

The present invention belongs to the field of electrical technology, and relates to a servo DC-DC converter topology applied to an intelligent robot. In the topology of a half-bridge LLC circuit, the positions of L and C are adjusted and reactive current is added simultaneously so that the switch tube works in a soft switching state throughout the whole process. The conduction duty cycle of the switch tube Q1 is theoretically 0-99.99%, and the corresponding transmission gain is 0-infinity, which effectively solves the problem of the narrow adjustment range of the LLC circuit; the reactive current is introduced and the reactive current loop is relatively independent, so that the primary switch tubes Q1 and Q2 and the secondary diodes D3 and D4 are fully soft-switched, which solves the problem of non-full-range soft switching of the lagging arm of the phase-shifted full-bridge circuit; the circuit is simple, the principle is clear, and it is insensitive to the parameter accuracy of all devices, especially the leakage inductance of the transformer T1, and the inductance values ​​of L1 and L2, which greatly reduces the requirements for hardware parameters during production, and at the same time reduces the heat dissipation requirements, greatly reduces the volume of the servo power supply, and fully meets the characteristic requirements of the servo DC-DC of the intelligent robot.

Description

Technical Field

[0001] The invention belongs to the field of electrical technology, and specifically relates to a follow-up DC-DC converter topology applied to an intelligent robot. Background Art

[0002] Intelligent robots are the main development targets in the 21st century. They are widely used. However, the working conditions of intelligent robots are very harsh. Especially powerful exterior wall cleaning robots need to work in high temperature and high humidity environments. Moreover, there are also very large restrictions on the volume of the electronic control part inside, which makes the power density requirements of the power supply part very demanding. The follow-up DC-DC of the intelligent robot is mainly installed inside the robot to provide power for the internal control equipment. The unstable high-voltage DC is introduced through the external follow-up cable, and then converted into low-voltage DC through the power supply for the electronic equipment inside the intelligent robot. Therefore, there are very high requirements for the volume, weight and efficiency of the follow-up power supply, which must meet the special requirements of being able to be put down, picked up, and low in temperature.

[0003] Although DC-DC has gradually developed many topological structures in the decades of development, a series of soft switching technologies have been born and developed with the efforts of many scholars and engineers at home and abroad, which has greatly changed the conversion efficiency of power supplies. Traditional ones include forward, flyback, push-pull, half-bridge, full-bridge hard switch, phase-shifted full-bridge, LLC, etc. Among them, forward, flyback, and push-pull are all hard switches, and their efficiency, volume, and weight limit their use in intelligent robot occasions; although the phase-shifted full-bridge and LLC topologies belong to the field of soft switching technology, both topologies have corresponding defects that need to be improved; for example, the phase-shifted full-bridge topology is not a full-range soft switch, and there is obvious hard switching loss under heavy and light loads, and the heat sink needs to be increased, which cannot meet the requirements of small size for intelligent robots; although LLC is a full-range soft switch, it has a narrow working range and cannot adapt to the requirements of a wide range, and it is difficult to meet the needs of the changing working environment of intelligent robots. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing phase-shifted full-bridge and LLC topology soft switching technologies, and propose a follow-up DC-DC converter topology applied to an intelligent robot. By adjusting the positions of L and C in the topology of a half-bridge LLC circuit, full-range soft switching is achieved with as few components as possible, thereby greatly improving the DC-DC efficiency, reducing the volume and EMI filter, and improving the efficiency.

[0005] In order to achieve the above-mentioned purpose, the main structure of a follow-up DC-DC converter topology applied to an intelligent robot described in the present invention includes an input support capacitor C2, a first inductor L1, a transformer T1, a first switch tube Q1 and an accompanying parasitic diode D1, a second switch tube Q2 and a parasitic diode D2, a DC support capacitor C1, secondary rectifier diodes D3, D4, a filtering second inductor L2 and an output filter capacitor C3; the gate drive waveforms of the first switch tube Q1 and the second switch tube Q2 are a pair of complementary PWM signals with dead time.

[0006] Phase 1: The first switch tube Q1 is turned on, the input voltage is applied to the primary side of the transformer T1, the first inductor L1 starts to store energy, the same-name end of the secondary winding of the transformer T1 induces a negative current, forcing the diode D4 to turn on, and the energy is supplied to the load through the filtering second inductor L2, while charging C3, and L2 starts to store energy.

[0007] The second stage: the first switch tube Q1 is turned off, the system enters the dead zone period, the second switch tube Q2 is not turned on yet, the first inductor L1 on the primary side of the transformer continues to flow through the parasitic diode D2 of the second switch tube Q2, forcing D2 to turn on and preparing for the second switch tube Q2 to turn on. At the same time, the first inductor L1 releases energy to the DC support capacitor C1, so that the voltage of the DC support capacitor C1 gradually increases; the main magnetic flux of the core of the transformer T1 is constrained by Lenz's law, and the secondary winding immediately induces a positive current at the same end, forcing the diode D4 to turn off and D3 to turn on. At the same time, the second filter inductor L2 on the secondary side of the transformer begins to release energy to maintain D3 on, and the second filter inductor L2 and the output filter capacitor C3 supply power to the load at the same time; since the cut-off of D4 and the conduction of D3 are both carried out spontaneously by continuous flow, D4 is soft-off and D3 is soft-on.

[0008] The third stage: after the dead time is over, the driving signal of the second switch tube Q2 drives the second switch tube Q2 to turn on. Since the diode D2 has been forward-conducted in the previous process, the second switch tube Q2 is turned on at zero voltage and has no loss. After the second switch tube Q2 is turned on, the conduction condition of the diode D2 is destroyed, and the diode D2 is turned off spontaneously. Due to the conduction of the second switch tube Q2, the energy stored in the DC support capacitor C1 begins to discharge to the primary side of the transformer T1 through the second switch tube Q2, and the input support capacitor C2 absorbs the excess energy that has not yet been transmitted to the secondary side of the transformer, and L1 starts to store energy in the reverse direction. The main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary side immediately induces a positive current at the same end, which continues to flow through the diode D3. The energy supplies power to the load through the second filter inductor L2, and charges the filter capacitor C3, while the second filter inductor L2 continues to store energy. Since the diode D3 has been turned on and the diode D4 has been turned off in the previous stage, there is no reverse recovery of D4 in this switching.

[0009] The fourth stage: the second switch tube Q2 is turned off, and the system enters the dead time again. Q1 has not yet turned on. The first inductor L1 on the primary side of the transformer begins to release energy in the reverse direction and continues to flow through the parasitic diode D1 of the first switch tube Q1, forcing the diode D1 to turn on and preparing for the first switch tube Q1 to turn on. The main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary side induces a negative current at the same end, forcing the diode D3 to turn off and D4 to turn on. At the same time, the second inductor L2 on the secondary side of the transformer T1 begins to release energy again, continuing to maintain the diode D4 to be turned on, and the filtering second inductor L2 and the filtering capacitor C3 again supply power to the load together. Since the cut-off of D3 and the conduction of D4 are both carried out spontaneously by continuous flow, D3 is soft-off and D4 is soft-on.

[0010] The next process returns to the first stage and starts to turn on the first switch tube Q1 again. Since D1 has been turned on in the last stage of the previous cycle, the first switch tube Q1 is turned on at zero voltage at this time, with no loss, and a new cycle begins.

[0011] The present invention implements a control process of a follow-up DC-DC converter topology applied to an intelligent robot, comprising the following steps:

[0012] (1) When the output voltage is higher than the set value, the on-time of the first switch tube Q1 is reduced, and the on-time of Q2 is increased accordingly.

[0013] (2) When the output voltage is lower than the set value, the on-time of the first switch tube Q1 is increased, and the on-time of Q2 is correspondingly reduced.

[0014] Compared with the prior art, the present invention has a theoretical on-duty ratio of the first switch tube Q1 and the second switch tube Q2 of 0-99.99%, and a corresponding transmission gain of 0-infinity, which effectively solves the problem of a narrow adjustment range of the LLC circuit; by introducing reactive current and making the reactive current loop relatively independent, the first switch tube Q1 and the second switch tube Q2 on the primary side and the rectifier diodes D3 and D4 on the secondary side are fully soft-switched, which effectively solves the problem of non-full-range soft switching of the lagging arm of the phase-shifted full-bridge circuit; the circuit is simple, the principle is clear, and it is insensitive to the parameter accuracy of all devices, especially the leakage inductance of the transformer T1 and the inductance values ​​of L1 and L2, which greatly reduces the requirements for hardware parameters during production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The topological principle diagram of a follow-up DC-DC converter applied to an intelligent robot described in the present invention.

[0016] Figure 2 This is a control step decomposition diagram of a follow-up DC-DC converter applied to an intelligent robot described in the present invention.

[0017] Figure 3 This is a working waveform diagram of a follow-up DC-DC converter applied to an intelligent robot described in the present invention. Implementation

[0018] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0019] ]Implementation Case:

[0020] The main structure of a follow-up DC-DC converter applied to an intelligent robot described in this implementation case includes a capacitor C2, a first inductor L1, a transformer T1, a first switch tube Q1 and an accompanying parasitic diode D1, a second switch tube Q2 and a parasitic diode D2, a DC support capacitor C1, secondary side rectifier diodes D3 and D4, a filtering second inductor L2 and an output filter capacitor C3; the gate drive waveforms of the first switch tube Q1 and the second switch tube Q2 are a pair of complementary PWM signals with dead time.

[0021] The first switch tube Q1 and the second switch tube Q2 and the corresponding parasitic diodes D1 and D2 form a half-bridge structure; wherein the source of Q2 is connected to the drain of Q1, and the source of Q1 is connected to the negative input terminal of the input source; the two poles of C1 are respectively connected to the drain of Q2 and the negative input terminal of the input source; the primary coil of the transformer T1 is connected in parallel with the L1 inductor, one end of the first inductor L1 is connected to the connection point of Q1 and Q2, and the other end is connected to the positive input terminal of the input source; C2 is connected in parallel between the positive input terminal and the negative input terminal of the input source circuit; the secondary double windings of the transformer T1 form a full-wave rectifier circuit through D3 and D4; the second inductor L2 is connected in series between the positive output terminal of the full-wave rectifier circuit and the positive electrode of the load; the negative output terminal of the full-wave rectifier circuit is directly connected to the negative electrode of the load; C3 is connected in parallel with the load to provide filtering for the DC-DC converter.

[0022] When the first switch tube Q1 is turned on, the input voltage is applied to the primary side of the transformer T1, the first inductor L1 starts to store energy, the rectifier D4 of the secondary side of the transformer T1 is turned on, and the electric energy is supplied to the load through the second inductor L2 while charging C3, and L2 starts to store energy.

[0023] When the first switch tube Q1 is turned off and the dead time begins, the second switch tube Q2 has not yet been turned on. The first inductor L1 on the primary side of the transformer continues to flow through the parasitic diode D2 of the second switch tube Q2, forcing D2 to turn on and preparing for the second switch tube Q2 to turn on. At the same time, the first inductor L1 releases energy to the support capacitor C1, causing the voltage of C1 to gradually increase; the main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary winding forces the diode D4 to turn off and D3 to turn on. At the same time, the second inductor L2 on the secondary side of the transformer begins to release energy to maintain the conduction of D3, and L2 and C3 supply power to the load at the same time; since the turn-off of D4 and the conduction of D3 are both carried out spontaneously by continuous flow, the two are zero current shutdown and zero voltage conduction respectively.

[0024] After the dead time is over, the driving signal of the second switch tube Q2 drives the second switch tube Q2 to turn on. Since D2 has been forward-conducted in the previous process, the second switch tube Q2 is turned on at zero voltage without loss. After the second switch tube Q2 is turned on, the electric energy stored in C1 begins to discharge to the primary side of the transformer T1 through the second switch tube Q2, and C2 absorbs the excess electric energy that has not yet been transmitted to the secondary side of the transformer, and L1 starts to store energy in the reverse direction. After induction by the secondary side of the transformer T1, D3 continues to be turned on, and the load is powered and C3 is charged through the second inductor L2. Since D3 has been turned on and D4 has been turned off in the previous process, D4 has no reverse recovery current.

[0025] The PWM cycle enters the next stage, the second switch tube Q2 is turned off and enters the dead time again, Q1 has not yet turned on, the first inductor L1 on the primary side of the transformer begins to release energy in the reverse direction, and continues to flow through the parasitic diode D1 of the first switch tube Q1, forcing D1 to turn on and prepare for the first switch tube Q1 to turn on; the second inductor L2 on the secondary side of the transformer T1 begins to release energy again, forcing D7 to turn on again, and turning off D4 and D5 at the same time. Since D7 is turned on when D4 and D5 are turned off, all D4 and D5 are turned off at zero voltage, and L2 and C3 supply power to the load together again; the next stage returns to the first stage and starts to turn on the first switch tube Q1 again, and a new cycle begins.

[0026] In this embodiment, the driving waveforms of the first switch tubes Q1 and Q2 are complementary PWM signal pairs containing dead time. When the output voltage of the DC-DC converter increases, the on-time of the first switch tube Q1 is reduced, and the on-time of the second switch tube Q2 is increased; when the output voltage decreases, the on-time of the first switch tube Q1 is increased, and the on-time of Q2 is reduced, thereby achieving output voltage stabilization.

[0027] The working process of a follow-up DC-DC converter topology applied to an intelligent robot described in this embodiment includes the following stages:

[0028] t0-t1 period: At t0, the first switch tube Q1 starts to turn on under the drive of the driving waveform. After the first switch tube Q1 is turned on, the input voltage is applied to the primary side of the transformer T1, the first inductor L1 starts to store energy, and the same-name end of the secondary winding of the transformer T1 induces a negative current, forcing the secondary diode D4 to turn on. The energy is supplied to the load through the second inductor L2, and C3 is charged at the same time. At the same time, L2 starts to store energy; when the first switch tube Q1 just starts to turn on, the current on the primary side of the transformer is 0 (initial power-on moment) or a negative value (normal working period), so the first switch tube Q1 is turned on with zero voltage.

[0029] Time period t1-t2: At time t1, the first switch tube Q1 is turned off under the driving waveform, and the system enters the dead zone time period. The second switch tube Q2 has not yet turned on. The first inductor L1 on the primary side of the transformer continues to flow through the parasitic diode D2 of the second switch tube Q2, forcing D2 to turn on and preparing for the second switch tube Q2 to turn on. At the same time, the first inductor L1 releases energy to the support capacitor C1, causing the voltage of C1 to gradually increase. The main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary winding immediately induces a positive current at the same end, forcing the diode D4 to turn off and D3 to turn on. At the same time, the second filter inductor L2 on the secondary side of the transformer begins to release energy to maintain D3 on. The second filter inductor L2 and the output filter capacitor C3 supply power to the load at the same time. Since the cut-off of D4 and the conduction of D3 are both carried out spontaneously by continuous flow, D4 is soft-off and D3 is soft-on.

[0030] Period t2-t3: At time t2, the second switch tube Q2 starts to conduct under the drive of the driving waveform. After the dead time is over, since D2 has been forward-conducted in the previous process, the conduction of the second switch tube Q2 is zero voltage conduction at this time, and there is no loss; after the second switch tube Q2 is turned on, the conduction condition of the diode D2 is destroyed, and the diode D2 is cut off spontaneously; due to the conduction of the second switch tube Q2, the energy stored in the DC support capacitor C1 begins to discharge to the primary side of the transformer T1 through the second switch tube Q2, and the input support capacitor C2 absorbs the excess energy that has not yet been transmitted to the secondary side of the transformer, and L1 starts to store energy in the reverse direction; the main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary side immediately induces a positive current at the same end, which continues to flow through the diode D3, and the energy is supplied to the load through the second filter inductor L2, and the filter capacitor C3 is charged, and the second filter inductor L2 continues to store energy; since the diode D3 has been turned on and the diode D4 has been cut off in the previous stage, there is no reverse recovery of D4 in this switching.

[0031] Time period t3-t4: At time t3, the second switch tube Q2 is turned off under the drive of the driving waveform, and the system enters a new dead zone time period; Q1 has not yet turned on, and the first inductor L1 on the primary side of the transformer begins to release energy in the reverse direction, and continues to flow through the parasitic diode D1 of the first switch tube Q1, forcing D1 to turn on and preparing for the first switch tube Q1 to turn on; the main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary side induces a negative current at the same end, forcing the diode D3 to turn off and D4 to turn on. At the same time, the second inductor L2 on the secondary side of the transformer T1 begins to release energy again, continuing to maintain the diode D4 to be turned on, and the filtering second inductor L2 and the filtering capacitor C3 again supply power to the load together; since the cut-off of D3 and the conduction of D4 are both carried out spontaneously by continuous flow, D3 is soft-off and D4 is soft-on.

[0032] Then a new cycle begins, and the system returns to the working state described in t0-t1, and the cycle continues over and over again.

Claims

1. A follow-up DC-DC converter topology applied to an intelligent robot, characterized in that: The first switch tube Q1 and the second switch tube Q2 and the corresponding parasitic diodes D1 and D2 form a half-bridge structure; wherein the source of the second switch tube Q2 is connected to the drain of the first switch tube Q1, and the source of the first switch tube Q1 is connected to the negative input terminal of the input source; the two electrodes of the DC support capacitor C1 are respectively connected to the drain of the second switch tube Q2 and the negative input terminal of the input source; the primary coil of the transformer T1 is connected in parallel with the first inductor L1, and one end of the first inductor L1 is connected to the first switch tube Q1 and the second switch tube The connection point of Q2, and the other end is connected to the positive input end of the input source; the input support capacitor C2 is connected in parallel between the positive input end and the negative input end of the input source circuit; the secondary double winding of the transformer T1 forms a full-wave rectifier circuit through the secondary rectifier diode D3 and the secondary rectifier diode D4; the second inductor L2 is connected in series between the positive output end of the full-wave rectifier circuit and the positive electrode of the load; the negative output end of the full-wave rectifier circuit is directly connected to the negative electrode of the load; the output filter capacitor C3 is connected in parallel with the load to provide minimum filtering for the DC-DC converter; The driving waveforms of the first switch tube Q1 and the second switch tube Q2 are a complementary PWM signal pair containing a dead time. When the output voltage of the DC-DC converter increases, the on-time of the first switch tube Q1 is reduced, and the on-time of the second switch tube Q2 is increased; when the output voltage decreases, the on-time of the first switch tube Q1 is increased, and the on-time of the second switch tube Q2 is reduced; The working process of the follow-up DC-DC converter topology includes: At time t0, the first switch tube Q1 starts to conduct under the drive of the driving waveform. When the first switch tube Q1 is turned on, the input voltage is applied to the primary side of the transformer T1, the first inductor L1 starts to store energy, and the same-name end of the secondary winding of the transformer T1 is induced as a negative current, forcing the secondary rectifier diode D4 to conduct. The energy is supplied to the load through the second inductor L2, and the output filter capacitor C3 is charged at the same time, and the second inductor L2 starts to store energy; At time t1, the first switch tube Q1 is turned off under the drive of the driving waveform, and the system enters the dead zone period. The second switch tube Q2 has not yet turned on. The first inductor L1 on the primary side of the transformer T1 continues current through the parasitic diode D2 of the second switch tube Q2, forcing the parasitic diode D2 to turn on and prepare for the second switch tube Q2 to turn on. At the same time, the first inductor L1 releases energy to the DC support capacitor C1, so that the voltage of the DC support capacitor C1 gradually increases; the main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary winding immediately induces a positive current at the same end, forcing the secondary rectifier diode D4 to turn off and the secondary rectifier diode D3 to turn on. At the same time, the second filter inductor L2 on the secondary side of the transformer T1 begins to release energy to maintain the secondary rectifier diode D3 to be turned on, and the second filter inductor L2 and the output filter capacitor C3 simultaneously supply power to the load; At time t2, the second switch tube Q2 starts to conduct under the drive of the driving waveform. After the dead time is over, since the parasitic diode D2 has been forward-conducted in the previous process, the second switch tube Q2 is turned on at zero voltage without loss. After the second switch tube Q2 is turned on, the conduction condition of the parasitic diode D2 is destroyed, and the parasitic diode D2 is cut off spontaneously. Due to the conduction of the second switch tube Q2, the energy stored in the DC support capacitor C1 begins to discharge to the primary side of the transformer T1 through the second switch tube Q2, and the input support capacitor C2 absorbs the excess energy that has not yet been transmitted to the secondary side of the transformer T1. At the same time, the first inductor L1 starts to store energy in the reverse direction. The main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary side immediately induces a positive current at the same end, which continues to flow through the secondary side rectifier diode D3. The energy is supplied to the load through the second filter inductor L2, and the output filter capacitor C3 is charged at the same time. At the same time, the second filter inductor L2 continues to store energy. At time t3, the second switch tube Q2 is turned off under the drive of the driving waveform, and the system enters a new dead zone period; the first switch tube Q1 has not yet been turned on, and the first inductor L1 on the primary side of the transformer T1 begins to release energy in the reverse direction, and continues to flow through the parasitic diode D1 of the first switch tube Q1, forcing the parasitic diode D1 to be turned on, and preparing for the first switch tube Q1 to be turned on; the main magnetic flux of the magnetic core of the transformer T1 is constrained by Lenz's law, and the secondary side induces a negative current at the same end, forcing the secondary side rectifier diode D3 to be turned off and the secondary side rectifier diode D4 to be turned on. At the same time, the second inductor L2 on the secondary side of the transformer T1 begins to release energy again, and continues to maintain the secondary side rectifier diode D4 to be turned on. The second filtering inductor L2 and the output filter capacitor C3 again supply power to the load together.

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