LED Street Light DC Bus Power Supply

Abstract

The present invention provides a DC bus power supply for LED street lamps, characterized in that: it includes a three-phase AC power supply; the three-phase AC power supply is a mains power supply, the zero line of the three-phase AC power supply is suspended and not grounded, the A-phase, B-phase and C-phase output ends of the three-phase AC power supply are respectively electrically connected to the A-phase, B-phase and C-phase input ends of the isolator, and the input end of the isolator is connected to a triangle or Y-shaped winding as a primary winding; the A-phase, B-phase and C-phase output ends of the isolator are respectively electrically connected to a group of coil windings as secondary windings; each group of coil windings includes two completely consistent and mutually reversely connected coil windings; one end of the three groups of coil windings is respectively electrically connected to the corresponding isolator output end, and the other ends of the three groups of coil windings are all electrically connected to a common point, and the common point is not grounded; the output end of the isolator is rectified by a rectifier to output a direct DC voltage to power the street lamp, without capacitor filtering. The present invention improves equipment safety and reduces power grid pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of street lamps, and in particular relates to a DC bus power supply for an LED street lamp. Background Art

[0002] LEDs are energy-saving and efficient, gradually replacing traditional gas discharge street lamps and are widely used in roads and tunnels. The LED excitation power supply is DC. The power supply of the power grid is mainly three-phase AC. In each circuit, it is single-phase AC. In order to ensure the three-phase balance in the three-phase circuit, the neutral line and the ground line share one electrode. The earth is always an electrode potential. Any phase of the three phases has a potential difference (220V) with the earth. Due to various reasons such as technology and nature, leakage of outdoor lamp poles is inevitable, causing various equipment and personnel casualties. If single-phase rectification is used, due to the large amplitude, electrolytic capacitor filtering must be added. Due to the characteristics of diodes, the harmonics of all electronic loads will cause large-scale harmonic pollution to the entire power grid. In the existing technology, capacitor filtering is mostly used, which has a large impact on the power grid when starting. After rectification, a large number of power grid harmonics are generated with diodes, affecting the safety of the power grid. Summary of the invention

[0003] The purpose of the present invention is to solve the deficiencies of the above-mentioned background technology and provide a DC bus power supply for LED street lamps to improve equipment safety and reduce pollution to the power grid.

[0004] The technical solution adopted by the present invention is: a DC bus power supply for LED street lamps, characterized by: a three-phase AC power supply; the three-phase AC power supply is a mains power supply, the zero line of the three-phase AC power supply is suspended and not grounded, the A-phase, B-phase and C-phase output ends of the three-phase AC power supply are respectively electrically connected to the A-phase, B-phase and C-phase input ends of the isolator, and the input end of the isolator is connected to a triangle or Y-shaped winding as a primary winding; the A-phase, B-phase and C-phase output ends of the isolator are respectively electrically connected to a group of coil windings as secondary windings; each group of coil windings includes two completely consistent and mutually reversely connected coil windings; one end of the three groups of coil windings is respectively electrically connected to the corresponding isolator output end, and the other ends of the three groups of coil windings are all electrically connected to a common point, and the common point is not grounded; the output end of the isolator is rectified by a rectifier to output a DC voltage to power the street lamp. Under this wiring mode, the DC voltage value of the power input end of the street lamp is 1.35 times the phase voltage of the three-phase AC power supply.

[0005] In the above technical solution, the rectifier includes a six-phase half-wave rectifier circuit; the six-phase half-wave rectifier circuit includes six parallel rectifier tubes, and the isolator output end corresponding to each coil winding is connected to the power input end of the street lamp through the corresponding rectifier tube; the conduction period of each rectifier tube is 1 / 6 of the three-phase AC power supply period, and the output current of each coil winding is 1 / 6 of the peak value of the output current of the three-phase AC power supply; at any time, only one rectifier tube is turned on.

[0006] In the above technical solution, the center taps of the reversely connected coil windings in each group of coil windings are connected via capacitors.

[0007] In the above technical solution, the rectifier includes two three-phase full-bridge rectifiers; the isolator output ends corresponding to the three positively connected coil windings are connected to the input end of one of the three-phase full-bridge rectifiers, and the isolator output ends corresponding to the three reversely connected coil windings are connected to the input end of the other three-phase full-bridge rectifier; the output ends of the two three-phase full-bridge rectifiers are connected in parallel or in series and connected to the power input end of the street lamp. Under this wiring method, the DC voltage value of the power input end of the street lamp is greater than 1.35 times the phase voltage of the three-phase AC power supply and less than 1.4 times the phase voltage of the three-phase AC power supply.

[0008] In the above technical solution, the three-phase full-bridge rectifier includes three parallel rectifier tubes, and each coil winding is connected to the power input terminal of the street lamp through the corresponding rectifier tube in the three-phase full-bridge rectifier; the conduction period of each rectifier tube is 1 / 12 of the three-phase AC power supply period, and the output current of each coil winding is 1 / 6 of the peak value of the output current of the three-phase AC power supply; among the six rectifier tubes of the two three-phase full-bridge rectifiers, only two rectifier tubes are turned on at any time.

[0009] In the above technical solution, each group of coil windings also includes another completely identical phase-shifting coil winding, which has a phase difference of 1 / 3π with the coil winding directly connected in the group; one end of the three phase-shifting coil windings is electrically connected to the corresponding isolator output end, and the other ends of the three groups of phase-shifting coil windings are all electrically connected to a common point; the three phase-shifting coil windings have center taps, and the center taps of the three phase-shifting coil windings are connected through capacitors.

[0010] In the above technical solution, the rectifier includes three three-phase full-bridge rectifiers; the isolator output ends corresponding to the three positively connected coil windings are electrically connected to the input end of one of the three-phase full-bridge rectifiers, and the isolator output ends corresponding to the three reversely connected coil windings are electrically connected to the input end of another three-phase full-bridge rectifier; the isolator output ends corresponding to the three phase-shifting coil windings are electrically connected to the input end of another three-phase full-bridge rectifier; the output ends of the three three-phase full-bridge rectifiers are connected in parallel or in series and are electrically connected to the power input end of the street lamp. Under this wiring method, the DC voltage value of the power input end of the street lamp is greater than 1.35 times the phase voltage of the three-phase AC power supply and less than 1.4 times the phase voltage of the three-phase AC power supply.

[0011] The above technical solution also includes a three-phase full-bridge rectifier including three parallel rectifier tubes, each coil winding is connected to the power input terminal of the street lamp through the corresponding rectifier tube in the three-phase full-bridge rectifier; the conduction period of each rectifier tube is 1 / 18 of the three-phase AC power supply period, and the output current of each coil winding is 1 / 6 of the peak value of the output current of the three-phase AC power supply; among the 9 rectifier tubes of the three three-phase full-bridge rectifiers, only 2 rectifier tubes are turned on at any time.

[0012] The above technical solution also includes a constant voltage source control circuit, the output ends of the three groups of coil windings are electrically connected to the power input end of the street lamp via the constant voltage source control circuit, and the constant voltage source control circuit includes a voltage sensor, a PWM controller and a switching circuit; the output ends of the three groups of coil windings are electrically connected to the power input end of the street lamp via the switching circuit, the voltage sensor is used to detect the input voltage of the power input end and feed it back to the PWM controller, and the PWM controller outputs a control signal to the switching circuit.

[0013] The above technical solution also includes a constant current source control circuit, the output ends of the three groups of coil windings are electrically connected to the power input end of the street lamp via the constant current source control circuit, and the constant voltage source control circuit includes a current sensor, a PWM controller and a switching circuit; the output ends of the three groups of coil windings are electrically connected to the power input end of the street lamp via the switching circuit, the current sensor is used to detect the input current of the power input end and feed it back to the PWM controller, and the PWM controller outputs a control signal to the switching circuit.

[0014] The beneficial effects of the present invention are as follows: the present invention uses a DC busbar power supply that is suspended from the ground and suitable for outdoor LED lighting, and changes the three-phase symmetrical power supply into 3x N phases through transformer windings and capacitor phase shifting, which can be set to 6 phases, 9 phases, and 12 phases as needed, and can solve the technical problem of three-phase imbalance without changing the existing lighting facilities. Whether the input of the present invention adopts a star or delta connection method, there is no need to connect the neutral line to an independent ground line to achieve lightning protection and shielding functions, and the busbar forms a potential to the ground. The earth and any pole of the busbar can avoid electric shock accidents, greatly reducing the probability of accidents. The present invention realizes the independence of both sides of the input and output through an isolator, which effectively improves safety. In addition, according to the characteristics of the LED light source, the present invention adopts a low-amplitude multi-pulsation filter-free capacitor suitable for constant current light drive, which is efficient and energy-saving, outputs a similar DC voltage and does not set capacitor filtering, does not generate impact current at any time, reduces the pollution of the capacitor discharge to the power grid, and plays a fundamental role in the safety of the power grid, solving the fatal short board of the electronic load. Electrolytic capacitor filtering In theory, the life of electronic products is determined by electrolytic capacitors. The present invention cancels the setting of inductors and capacitors, effectively extending the life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A is a circuit diagram of the present invention;

[0016] Figure 2 is the output waveform diagram a of the present invention;

[0017] Figure 3 is a circuit schematic diagram b of the present invention;

[0018] Figure 4 is the output waveform diagram b of the present invention;

[0019] Figure 5 is a circuit schematic diagram c of the present invention;

[0020] Figure 6 is the output waveform diagram c of the present invention;

[0021] Figure 7 The constant voltage source control circuit of the present invention;

[0022] Figure 8 This is the constant current source control circuit of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but they do not constitute a limitation on the present invention.

[0024] like Figure 1As shown, the present invention provides a DC bus power supply for LED street lamps, characterized in that: it includes a three-phase AC power supply; the three-phase AC power supply is a mains power supply, the neutral line of the three-phase AC power supply is suspended and not grounded, the A-phase, B-phase and C-phase output ends of the three-phase AC power supply are respectively electrically connected to the A-phase, B-phase and C-phase input ends of the isolator, and the A-phase, B-phase and C-phase output ends of the isolator are respectively electrically connected to a group of coil windings; each group of coil windings includes two completely consistent and mutually reversely connected coil windings, namely A1-A2, B1-B2, and C1-C2; one end of the three groups of coil windings is respectively electrically connected to the corresponding isolator output end, the other ends of the three groups of coil windings are all electrically connected to a common point, and the common point is not grounded, the isolator outputs a DC voltage through a rectifier to power the street lamp, and there is no capacitor filtering on the DC output side. Figure 1 The straight line in the middle represents the isolator, and the triangle in the triangle represents the primary winding of the isolator. Its three corners are connected to the A-phase, B-phase, and C-phase input terminals of the isolator. The A-terminal, B-terminal, and C-terminal on the right side of the isolator end, end, The terminals are respectively the positive and negative three-phase output terminals of the isolator, namely the A-phase, B-phase and C-phase output terminals, and the three sets of coil windings connected thereto are the secondary windings of the isolator.

[0025] In the above technical solution, the rectifier includes a six-phase half-wave rectifier circuit; the six-phase half-wave rectifier circuit includes six parallel rectifier tubes, and the isolator output end corresponding to each coil winding is connected to the power input end of the street lamp through the corresponding rectifier tube; each rectifier tube and each coil winding has only 1 / 6 of the output current per cycle and only 2 rectifier tubes are turned on in each cycle.

[0026] The input three-phase connection is either star-shaped Y or delta-shaped Δ. Each phase of the isolated output has two identical coil windings, which are connected to a common point after being anti-phase connected to each other. The output is a six-pulse six-phase power supply with equal amplitude and 2 / 3π symmetry. The output waveform is as follows: Figure 2 As shown, after adjusting the amplitude and period, the output waveform can be approximated to direct current.

[0027] like Figure 1 The six-phase half-wave rectifier circuit is equivalent to full-wave rectification. Due to the complete symmetry, the output current of each rectifier tube and coil per cycle is only 1 / 6 of the input current amplitude, and only two diodes are turned on per cycle, and the conduction loss is only 1 / 4 of that of the full-wave rectifier. In full-wave rectification, each diode conduction cycle is 1 / 6 of the three-phase power supply cycle, and the conduction voltage drop is twice that of the half-wave. In low-voltage and high-current applications, the efficiency is high, the rectifier tube generates less heat, and the reliability is high, such as electrochemical power supply metallurgical medium-frequency furnace and arc furnace.

[0028] like Figure 3 As shown, in Figure 1Based on the scheme shown, the center taps of the reversely connected coil windings A2, B2, and C2 in each set of coil windings are connected through capacitor C. Capacitor C is used as a phase shifting capacitor. The A, B, and C terminals on the right side of the isolator are connected to the center taps of the reversely connected coil windings A2, B2, and C2. end, end, The terminals are respectively the positive and negative three-phase output terminals of the isolator, namely the A-phase, B-phase and C-phase output terminals, and the three sets of coil windings connected thereto are the secondary windings of the isolator.

[0029] In the above technical solution, the rectifier includes two three-phase full-bridge rectifiers; the isolator output terminals A, B, and C corresponding to the three positively connected coil windings A1, B1, and C1 are electrically connected to the input terminal of one of the three-phase full-bridge rectifiers, and the isolator output terminals A, B, and C corresponding to the three reversely connected coil windings A2, B2, and C2 are electrically connected to the input terminal of one of the three-phase full-bridge rectifiers. end, end, The end is electrically connected to the input end of another three-phase full-bridge rectifier; the output ends of the two three-phase full-bridge rectifiers are connected in parallel or in series and electrically connected to the power input end of the street lamp, outputting a 12-pulse six-phase power supply. The input end of a three-phase full-bridge rectifier is connected to three positively connected coil windings, and its output voltage is Vo1; the input end of the other three-phase full-bridge rectifier is connected to three reversely connected coil windings, and its output voltage is Vo2. Vo1 and Vo2 can be connected in series or in parallel through different wiring methods according to actual needs. The two output voltages are connected to the power input end of the street lamp, and the corresponding DC output side has no capacitor filtering. The waveform of the voltage Vo at the power input end of the street lamp is as shown in the figure Figure 4 As shown, after adjusting the amplitude and period, the waveform can be approximated as direct current. Vo = 1.35Vi < 1.4Vi, where Vi is the effective value of the AC input phase voltage. Vo = Vo1 + Vo2 or Vo1 / / Vo2

[0030] like Figure 5 As shown, in Figure 3 On the basis of the technical solution shown, each group of coil windings also includes another completely identical phase-shifting coil winding A3, B3, C3, which has a phase difference of 1 / 3π with the directly connected coil windings A1, B1, C1 in this group; one end of the three phase-shifting coil windings A3, B3, C3 is electrically connected to the corresponding isolator output terminals A', B', and C', respectively, and the other ends of the three groups of phase-shifting coil windings A3, B3, and C3 are all electrically connected to a common point O; the three phase-shifting coil windings have center taps, and the center taps of the three phase-shifting coil windings are connected through capacitors. The A, B, and C ends on the right side of the isolator / end, end, The A', B' and C' terminals are respectively the positive and negative phase and phase shift three-phase output terminals of the isolator, namely the A-phase, B-phase and C-phase output terminals, and the three sets of coil windings connected thereto are the secondary windings of the isolator.

[0031] In the above technical solution, the rectifier includes three three-phase full-bridge rectifiers; the isolator output terminals A, B, and C corresponding to the three positively connected coil windings A1, B1, and C1 are electrically connected to the input terminal of one of the three-phase full-bridge rectifiers, and the isolator output terminals A, B, and C corresponding to the three reversely connected coil windings A2, B2, and C2 are electrically connected to the input terminal of one of the three-phase full-bridge rectifiers. end, end, The end is electrically connected to the input end of another three-phase full-bridge rectifier; the isolator output ends A', B' and C' corresponding to the three phase-shifting coil windings A3, B3 and C3 are electrically connected to the input end of another three-phase full-bridge rectifier; the output ends of the three three-phase full-bridge rectifiers are connected in parallel or in series and electrically connected to the power input end of the street lamp, outputting 18-pulse 9-phase power. The input end of a three-phase full-bridge rectifier is connected to three positively connected coil windings, and its output voltage is Vo1; the input end of another three-phase full-bridge rectifier is connected to three reversely connected coil windings, and its output voltage is Vo2; the input end of another three-phase full-bridge rectifier is connected to three phase-shifted coil windings, and its output voltage is Vo3. Vo1, Vo2 and Vo3 can be connected in series or in parallel through different wiring methods according to actual needs. The three output voltages are connected to the power input end of the street lamp, and there is no capacitor filtering on the corresponding DC output side. The waveform of the voltage Vo at the power input end of the street lamp is as follows Figure 6 As shown, after adjusting the amplitude and period, the output waveform can be approximated as direct current. Vo = 1.35Vi < 1.4Vi, where Vi is the effective value of the AC input phase voltage. Vo = Vo1 + Vo2 + Vo3 or Vo1 / / Vo2 / / Vo3. When three phases (different phases) are output in parallel, the output DC voltage needs to be equal and a balancing reactor needs to be added. When outputting in series, there is no voltage limit. Generally, large currents are connected in parallel, and the series voltage is high.

[0032] like Figure 7 As shown, it also includes a constant voltage source control circuit, the output ends of the three sets of coil windings are electrically connected to the power input end of the street lamp through the constant voltage source control circuit, and the constant voltage source control circuit includes a voltage sensor 3, a PWM controller 2 and a switch circuit 1; the switch circuit 1 uses a MOS tube or an IGBT. The output end of the isolator is electrically connected to the power input end Vo of the street lamp through the switch circuit 1, and the voltage sensor 3 is used to detect the input voltage of the power input end and feed it back to the PWM controller 2, and the PWM controller 2 outputs a control signal to the switch circuit 1.

[0033] like Figure 8As shown, it also includes a constant current source control circuit, the output ends of the three sets of coil windings are electrically connected to the power input end of the street lamp through the constant current source control circuit, and the constant voltage source control circuit includes a current sensor 4, a PWM controller 2 and a switch circuit 1; the switch circuit 1 uses a MOS tube or an IGBT. The output end of the isolator is electrically connected to the power input end Vo of the street lamp through the switch circuit 1, the current sensor 4 is used to detect the input current of the power input end and feed it back to the PWM controller 2, and the PWM controller 2 outputs a control signal to the switch circuit 1.

[0034] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A DC bus power supply for LED street lamps, characterized in that: It comprises a three-phase AC power supply; the three-phase AC power supply is a mains power supply, the neutral line of the three-phase AC power supply is suspended and not grounded, the A-phase, B-phase and C-phase output ends of the three-phase AC power supply are respectively electrically connected to the A-phase, B-phase and C-phase input ends of the isolator, and the input end of the isolator is connected to a triangle or Y-shaped winding as a primary winding; the A-phase, B-phase and C-phase output ends of the isolator are respectively electrically connected to a group of coil windings as secondary windings; each group of coil windings comprises two completely identical and mutually reversely connected coil windings; one end of the three groups of coil windings is respectively electrically connected to the corresponding isolator output end, and the other ends of the three groups of coil windings are all electrically connected to a common point, and the common point is not grounded; the output end of the isolator is rectified by a rectifier to output a DC voltage to power a street lamp; The rectifier includes a 3×N phase rectifier circuit; The center taps of the reversely connected coil windings in each group of coil windings are connected via capacitors.

2. The DC bus power supply for LED street lamp according to claim 1, characterized in that: The rectifier includes a six-phase half-wave rectifier circuit; the six-phase half-wave rectifier circuit includes six parallel rectifier tubes, and the isolator output end corresponding to each coil winding is connected to the power input end of the street lamp through the corresponding rectifier tube; the conduction period of each rectifier tube is 1 / 6 of the three-phase AC power supply period, and the output current of each coil winding is 1 / 6 of the peak value of the output current of the three-phase AC power supply; at any time, only one rectifier tube is turned on.

3. The DC bus power supply for LED street lamp according to claim 1, characterized in that: The rectifier includes two three-phase full-bridge rectifiers; the isolator output ends corresponding to the three positively connected coil windings are electrically connected to the input end of one of the three-phase full-bridge rectifiers, and the isolator output ends corresponding to the three reversely connected coil windings are electrically connected to the input end of the other three-phase full-bridge rectifier; the output ends of the two three-phase full-bridge rectifiers are connected in parallel or in series and are electrically connected to the power input end of the street lamp.

4. The DC bus power supply for LED street lamp according to claim 3, characterized in that: Each coil winding is connected to the power input terminal of the street lamp via the corresponding rectifier tube in the three-phase full-bridge rectifier; the conduction period of each rectifier tube is 1 / 12 of the three-phase AC power period, and the output current of each coil winding is 1 / 6 of the peak value of the output current of the three-phase AC power; among the six rectifier tubes of the two three-phase full-bridge rectifiers, only two rectifier tubes are turned on at any time.

5. The DC bus power supply for LED street lamp according to claim 1, characterized in that: Each group of coil windings also includes another completely consistent phase-shifting coil winding, which has a phase difference of 1 / 3π with the directly connected coil winding in the group; one end of the three phase-shifting coil windings is electrically connected to the corresponding isolator output end, and the other ends of the three groups of phase-shifting coil windings are all electrically connected to a common point; the three phase-shifting coil windings have center taps, and the center taps of the three phase-shifting coil windings are connected through capacitors.

6. The DC bus power supply for LED street lamp according to claim 4, characterized in that: The rectifier includes three three-phase full-bridge rectifiers; the isolator output ends corresponding to the three positively connected coil windings are electrically connected to the input end of one of the three-phase full-bridge rectifiers, and the isolator output ends corresponding to the three reversely connected coil windings are connected to the input end of another three-phase full-bridge rectifier; the isolator output ends corresponding to the three phase-shifting coil windings are connected to the input end of another three-phase full-bridge rectifier; the output ends of the three three-phase full-bridge rectifiers are connected in parallel or in series and connected to the power input end of the street lamp.

7. The DC bus power supply for LED street lamp according to claim 6, characterized in that: Each coil winding is connected to the power input terminal of the street lamp via the corresponding rectifier tube in the three-phase full-bridge rectifier; the conduction period of each rectifier tube is 1 / 18 of the three-phase AC power period, and the output current of each coil winding is 1 / 6 of the peak value of the output current of the three-phase AC power; among the 9 rectifier tubes of the 3 three-phase full-bridge rectifiers, only 2 rectifier tubes are turned on at any time.

8. A DC bus power supply for LED street lamps according to any one of claims 2, 3 and 6, characterized in that: It also includes a constant voltage source control circuit, the output ends of the three groups of coil windings are connected to the power input end of the street lamp via the constant voltage source control circuit, and the constant voltage source control circuit includes a voltage sensor, a PWM controller and a switching circuit; the output ends of the three groups of coil windings are connected to the power input end of the street lamp via the switching circuit, the voltage sensor is used to detect the input voltage of the power input end and feed it back to the PWM controller, and the PWM controller outputs a control signal to the switching circuit.

9. A DC bus power supply for LED street lamps according to any one of claims 2, 4 and 7, characterized in that: It also includes a constant current source control circuit, the output ends of the three groups of coil windings are connected to the power input end of the street lamp via the constant current source control circuit, and the constant current source control circuit includes a current sensor, a PWM controller and a switching circuit; the output ends of the three groups of coil windings are connected to the power input end of the street lamp via the switching circuit, the current sensor is used to detect the input current of the power input end and feed it back to the PWM controller, and the PWM controller outputs a control signal to the switching circuit.

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