Frequency conversion inverter power supply for subway and subway power supply equipment

Abstract

The utility model discloses a frequency conversion inverter power supply for a subway and subway power supply equipment. The frequency conversion inverter power supply comprises an alternating current power supply circuit, a direct current power supply circuit, a first capacitor and a first inverter circuit, the AC power supply circuit comprises a first diode rectification circuit. The direct-current power supply circuit comprises a second inverter circuit and a second diode rectifying circuit; the input end of the first diode rectifying circuit is connected with the alternating current output end; the input end of the second inverter circuit is connected with the direct current output end, and the output end of the second inverter circuit is connected with the input end of the second diode rectifying circuit; the output end of the first diode rectification circuit and the output end of the second diode rectification circuit are connected with the first capacitor and output direct current to the first capacitor. The first capacitor is connected with the input end of the first inverter circuit and discharges to the first inverter circuit; and the output end of the first inverter circuit is connected with a load. Through reverse cut-off of the diode, smooth switching of power supply from alternating current and direct current to a load is realized, the overall cost is reduced, and the service life of the circuit is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to subway power supply technical field especially relates to a subway uses frequency conversion inverter power supply and subway power supply equipment. BACKGROUND

[0002] In the subway industry, due to the rise and fall of the pantograph, the subway needs to switch different power supply to power supply. The current subway generally adopts 380V three-phase alternating current and 110V direct current to switch the power supply through the relay. When the pantograph falls, 110V direct current is used for power supply, the relay switches to the 110V direct current input port, and BOOST is used to increase the voltage to 110V direct current to power the inverter. When the pantograph rises, the relay switches to the 540V direct current input port, and 380V three-phase alternating current is rectified to 540V direct current for power supply.

[0003] In the process of realizing the utility model creation, the inventor finds that at least the following problems exist in the prior art: frequent switching of the relay can cause serious decline in the service life of the relay.

[0004] Therefore, how to realize lower cost and longer life for subway power supply switching is a problem to be solved at present. UTILITY MODEL CONTENTS

[0005] Therefore, the utility model provides a frequency conversion inverter power supply for subway, which can realize lower cost and longer life for subway power supply switching. Another purpose of the utility model is to provide a subway power supply equipment comprising the above-mentioned frequency conversion inverter power supply for subway.

[0006] The specific scheme is as follows:

[0007] In order to effectively solve the above technical problems, the application provides a frequency conversion inverter power supply for subway, which comprises: an alternating current power supply circuit, a direct current power supply circuit, a first capacitor and a first inverter circuit; wherein the alternating current power supply circuit comprises a first diode rectifier circuit; the direct current power supply circuit comprises a second inverter circuit and a second diode rectifier circuit;

[0008] The input end of the first diode rectifier circuit is connected with the alternating current output end;

[0009] The input end of the second inverter circuit is connected with the direct current output end, and the output end of the second inverter circuit is connected with the input end of the second diode rectifier circuit;

[0010] The output end of the first diode rectifier circuit and the output end of the second diode rectifier circuit are both connected with the first capacitor, for outputting direct current to the first capacitor;

[0011] The first capacitor is connected with the input end of the first inverter circuit, and is used for discharging to the first inverter circuit.

[0012] The output end of the first inverter circuit is used for being connected with a load.

[0013] As an optional solution, in the above subway variable frequency inverter power supply, the DC output end outputs K1V DC, the AC output end outputs K2V three-phase AC, and the second inverter circuit comprises a boost inverter circuit and a resonance circuit, wherein K1 is less than K2.

[0014] As an optional solution, in the above subway variable frequency inverter power supply, the boost inverter circuit comprises a first switch tube, a second switch tube, a first inductor, a second inductor and a third inductor.

[0015] The second end of the first switch tube is connected with the second end of the second switch tube, and the common end thereof is used as the first input end of the second inverter circuit; the second end of the first inductor is connected with the first end of the third inductor, and the common end thereof is used as the second input end of the second inverter circuit; the input end of the second inverter circuit comprises the first input end of the second inverter circuit and the second input end of the second inverter circuit.

[0016] The first end of the first inductor is connected with the first end of the first switch tube.

[0017] The first inductor and the third inductor are the low-voltage side of a transformer; the second inductor is the high-voltage side of the transformer; and the two ends of the second inductor are used as the output end of the second inverter circuit.

[0018] As an optional solution, in the above subway variable frequency inverter power supply, the resonance circuit comprises a fourth inductor and a second capacitor.

[0019] The first end of the second capacitor is connected with the first end of the second inductor; and the second end of the second capacitor is connected with the first end of the fourth inductor.

[0020] The second end of the second inductor is used as the first output end of the second inverter circuit; the second end of the fourth inductor is used as the second output end of the second inverter circuit; and the output end of the second inverter circuit comprises the first output end of the second inverter circuit and the second output end of the second inverter circuit.

[0021] As an optional solution, in the above subway variable frequency inverter power supply, the second diode rectifier circuit is a single-phase bridge rectifier circuit.

[0022] As an optional solution, in the above subway variable frequency inverter power supply, the first diode rectifier circuit is a three-phase bridge rectifier circuit.

[0023] As an optional solution, the above subway variable frequency inverter power supply, the first inverter circuit comprises: third switch tube, fourth switch tube, fifth switch tube, sixth switch tube, seventh switch tube, eighth switch tube;

[0024] The first end of the third switch tube, the first end of the fifth switch tube and the first end of the seventh switch tube are connected to each other, and the common end is used as the first input end of the first inverter circuit;

[0025] The second end of the fourth switch tube, the second end of the sixth switch tube and the second end of the eighth switch tube are connected to each other, and the common end is used as the second input end of the first inverter circuit; the input end of the first inverter circuit includes the first input end of the first inverter circuit and the second input end of the first inverter circuit;

[0026] The second end of the third switch tube is connected to the first end of the fourth switch tube, and the common end is used as the first output end of the first inverter circuit;

[0027] The second end of the fifth switch tube is connected to the first end of the sixth switch tube, and the common end is used as the second output end of the first inverter circuit;

[0028] The second end of the seventh switch tube is connected to the first end of the eighth switch tube, and the common end is used as the third output end of the first inverter circuit;

[0029] The output end of the first inverter circuit includes the first output end of the first inverter circuit, the second output end of the first inverter circuit and the third output end of the first inverter circuit.

[0030] As an optional solution, the above subway variable frequency inverter power supply further comprises: a single-chip microcomputer, a power supply chip and a driving chip, for stopping outputting an enable signal to the power supply chip when detecting that the AC output end outputs AC power, so that the DC power supply circuit stops demanding energy from the battery, and outputting the enable signal to the power supply chip when detecting that the AC output end has no output, so that the DC power supply circuit starts working;

[0031] The enable signal output end of the single-chip microcomputer is connected to the control end of the power supply chip, for outputting the enable signal to the power supply chip, and the three-phase input voltage sampling end of the single-chip microcomputer is connected to the AC output end, for detecting whether the AC output end has output;

[0032] The output end of the power supply chip is connected to the driving chip, for outputting a PWM signal to the driving chip;

[0033] The driving chip is connected with the control end of each switch tube in the second inverter circuit, and is used for driving the second inverter circuit to inversely change the direct current into alternating current.

[0034] As an alternative, the above subway frequency conversion inverter power supply further comprises a first pre-charging circuit and a second pre-charging circuit; wherein the first pre-charging circuit comprises a first resistor, a first switch and a third capacitor, and the second pre-charging circuit comprises a second resistor and a second switch;

[0035] The first switch and the second switch are connected with the single-chip microcomputer, and are used for controlling the pre-charging process;

[0036] The first switch is connected with the first resistor in parallel, and the input end of the second inverter circuit is connected with the direct current output end through the first resistor;

[0037] The third capacitor is connected between the input ends of the second inverter circuit;

[0038] The second switch is connected with the second resistor in parallel, and the output end of the first diode rectifier circuit is connected with the first capacitor through the second resistor.

[0039] In order to effectively solve the above technical problems, the application further provides a subway power supply equipment comprising the above subway frequency conversion inverter power supply.

[0040] Compared with the prior art, the technical scheme provided by the application has at least the following beneficial effects:

[0041] The subway variable frequency inverter power supply provided by the application is composed of an alternating current power supply circuit, a direct current power supply circuit, a first capacitor and a first inverter circuit, the output end of the direct current power supply circuit and the output end of the alternating current power supply circuit are connected with the first capacitor to charge the first capacitor, the first capacitor is connected with the first inverter circuit to discharge to the first inverter circuit, wherein the alternating current power supply circuit is composed of a first diode rectifier circuit, and the direct current power supply circuit is composed of a second inverter circuit and a second diode rectifier circuit. As can be seen from the above, the direct current power supply circuit and the alternating current power supply circuit both charge the first capacitor, and then supply power to the load through the first inverter circuit. When the direct current voltage at the output end of the alternating current power supply circuit is higher than the direct current voltage at the output end of the direct current power supply circuit, the diode in the second diode rectifier circuit automatically cuts off, the circuit between the alternating current power supply circuit and the first capacitor is conducted, and at this time, the alternating current supplies power to the subway. When the direct current voltage at the output end of the alternating current power supply circuit is lower than the direct current voltage at the output end of the direct current power supply circuit, the diode in the first diode rectifier circuit reversely cuts off, the circuit between the direct current power supply circuit and the first capacitor is conducted, and at this time, the direct current supplies power to the subway. Therefore, when the output of the alternating current output end changes due to the lifting of the pantograph of the subway, the application can realize the smooth switching of the direct current and the alternating current through the reverse cut-off of the diode based on simple circuit elements, instead of the switching of the relay, thereby reducing the overall cost and prolonging the service life of the circuit. In summary, the subway variable frequency inverter power supply provided by the application can realize the low-cost and long-life subway power supply switching. The subway power supply equipment provided by the application comprises the subway variable frequency inverter power supply, and thus has the same technical effects as the subway variable frequency inverter power supply. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiment or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0043] Figure 1 A specific subway variable frequency inverter power supply is provided for the embodiment;

[0044] Figure 2 A waveform diagram of the first switch tube in the push-pull quasi-resonant circuit provided for the embodiment;

[0045] Figure 3 A subway variable frequency inverter power supply regulated by a single-chip microcomputer is provided for the embodiment;

[0046] The reference signs are as follows, 10 is a direct current power supply circuit, 20 is an alternating current power supply circuit, 30 is a first inverter circuit, 110 is a second inverter circuit, 120 is a second diode rectifier circuit, 111 is a boost inverter circuit, and 112 is a resonance circuit. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the utility model.

[0048] In order for the personnel in the technical field to better understand the scheme of the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0049] In the subway industry, due to the rising and lowering of the pantograph, the subway needs to switch different power sources for power supply. At present, 380V three-phase alternating current and 110V direct current are commonly used on the subway to switch the power supply through a relay. When the pantograph is lowered, 110V direct current is used for power supply, the relay is switched to the 110V direct current input port, BOOST is used to boost the 110V direct current voltage to supply power to the inverter. When the pantograph is raised, the relay is switched to the 540V direct current input port, and 380V three-phase alternating current is rectified to 540V direct current for power supply.

[0050] However, frequent switching of the relay can cause a significant decrease in the service life of the relay.

[0051] Therefore, how to switch the power supply of the subway with low cost and long service life is a problem to be solved at present.

[0052] In order to effectively solve the above problems, as shown in the drawings, Figure 1 The utility model discloses a variable frequency inverter power supply for subway, which comprises an alternating current power supply circuit 20, a direct current power supply circuit 10, a first capacitor C1 and a first inverter circuit 30.

[0053] The input end of the first diode rectifier circuit is connected with the alternating current output end.

[0054] The input end of the second inverter circuit 110 is connected with the direct current output end, and the output end of the second inverter circuit 110 is connected with the input end of the second diode rectifier circuit 120.

[0055] The output end of the first diode rectifier circuit and the output end of the second diode rectifier circuit 120 are connected with the first capacitor C1, for outputting direct current to the first capacitor C1;

[0056] The first capacitor C1 is connected with the input end of the first inverter circuit 30, for discharging to the first inverter circuit 30.

[0057] The output end of the first inverter circuit 30 is used for connecting with the load.

[0058] In the embodiment, the subway has a pantograph structure, the pantograph is connected with the overhead contact line when it is raised, the alternating current output end starts to output alternating current, and the pantograph is lowered, the alternating current output end stops outputting alternating current. It can be understood that the overhead contact line usually provides high-voltage direct current, which cannot be directly provided to the load for power supply, so the pantograph also needs to be connected with an auxiliary inverter power supply, and the high-voltage direct current output by the overhead contact line is converted into alternating current with lower voltage by the auxiliary inverter power supply, and then input to the alternating current power supply circuit, that is, the output end of the auxiliary inverter power supply is the above-mentioned alternating current output end. The direct current is provided by the battery in the subway, that is, the output end of the battery is the above-mentioned direct current output end. Similarly, the above-mentioned subway frequency conversion inverter power supply also needs to convert the direct current output by the first capacitor C1 into three-phase variable-frequency alternating current through the first inverter circuit 30, Figure 1 The UVW inverter output in the above-mentioned formula is the output end of the first inverter circuit.

[0059] In a specific embodiment, when the above-mentioned subway frequency conversion inverter power supply is applied to the subway air conditioning equipment, 380V alternating current and 110V direct current power supply switching mode is adopted, the pantograph is connected with the overhead contact line when the pantograph is raised, at this time, the overhead contact line outputs 1000V high-voltage direct current which can be input to the subway through the pantograph, and the auxiliary inverter power supply in the subway converts the above-mentioned 1000V direct current into 380V alternating current, the alternating current output end inputs the above-mentioned 380V alternating current into the alternating current power supply circuit, and when the pantograph is lowered, the connection between the pantograph and the overhead contact line is disconnected, and the alternating current output end has no output.

[0060] In the embodiment, the above-mentioned direct current power supply circuit 10 includes a second inverter circuit 110 and a second diode rectifier circuit 120, and in a specific embodiment, the above-mentioned second inverter circuit 110 can be a full-bridge inverter circuit composed of four switching tubes.

[0061] In another specific embodiment, the second inverter circuit 110 is a boost inverter circuit 111, which can be a push-pull square wave generator composed of two switching tubes and a transformer. The inverter output is boosted and then output to the second diode rectifier circuit 120. The boost ratio is 5. It should be noted that the power demand of the subway is very large, and usually needs 750V to 1500V DC to power it. If a battery with an output voltage of 750V is directly loaded on the subway, it will inevitably make the battery too large in size and weight, causing installation and maintenance difficulties and increasing the load of the subway. Therefore, the battery loaded on the subway needs to use the boost inverter circuit 111 to boost the output DC of the battery to power the subway.

[0062] As shown in Figure 1 The DC power supply circuit 10 adopts a push-pull quasi-resonant circuit with an open-loop structure, which can not only realize the inversion and boosting of DC power, but also realize zero-current turn-on and zero-current turn-off of the switching tube, with extremely small switching loss and high efficiency of up to 96%. The push-pull quasi-resonant circuit is a soft switching boost circuit, unlike the traditional hard switching circuit, and the EMI (Electromagnetic Interference) generated is also extremely small. Figure 2 The waveform diagram of the first switching tube M1 in the push-pull quasi-resonant circuit is shown in the figure, in which the square wave is the driving waveform of the first switching tube M1, the sine wave is the current flowing through the first switching tube M1, the left vertical axis is the voltage value in V, the right vertical axis is the current value in A, and the horizontal axis is the time in μs. It can be seen that when the driving waveform of the first switching tube M1 changes, the current flowing through the first switching tube M1 can quickly respond, and at the moment when the control end of the first switching tube M1 changes the conduction state of the first switching tube M1, the current flowing through the first switching tube M1 fluctuates very little, that is, the switching loss is also very small.

[0063] It can be understood that when the pantograph is raised, the overhead contact network via the AC power output by the pantograph and the auxiliary power supply can not only power the subway, but also simultaneously charge the battery on the subway to ensure the stability of the power supply of the subway.

[0064] It should be noted that the power supply mode of the subway can also be changed with the raising and lowering of the pantograph, switching between the AC output from the AC power supply circuit 20 and the DC output from the DC power supply circuit 10. In this embodiment, the first diode rectifier circuit and the second diode rectifier circuit 120 are both circuits containing diode structures. Due to the unidirectional conduction of the diodes in the circuits, when the DC voltage at the output end of the AC power supply circuit 20 is greater than the DC voltage at the output end of the DC power supply circuit 10, the diodes in the second diode rectifier circuit 120 are reverse-biased and cut off, and the DC power supply circuit 10 cannot output current, and the subway is powered by three-phase AC power. When the DC voltage at the output end of the DC power supply circuit 10 is greater than the DC voltage at the output end of the AC power supply circuit 20, the diodes in the first diode rectifier circuit are reverse-biased and cut off, and the AC power supply circuit 20 cannot output current, and the subway is powered by DC power.

[0065] In one specific embodiment, the first diode rectifier circuit and the second diode rectifier circuit 120 are both uncontrolled bridge rectifier circuits composed of diodes. In another specific embodiment, the first diode rectifier circuit and the second diode rectifier circuit 120 are both fully controlled bridge rectifier circuits composed of thyristors. At this time, not only can the unidirectional conduction of the diodes be used to switch the power supply mode, but also the switching of the power supply mode can be achieved by controlling the turn-off of the thyristors. It can be understood that the thyristors also contain diode structures and can achieve the same reverse-biased and cut-off effect as the diodes.

[0066] In this embodiment, the first capacitor C1 is connected to the output end of the DC power supply circuit 10 and the output end of the AC power supply circuit 20 at the same time, and is used to store the electrical energy output by the DC power supply circuit 10 and the AC power supply circuit 20. The first capacitor C1 then discharges itself to input DC power into the first inverter circuit 30. At the same time, since the DC power supply circuit 10 and the AC power supply circuit 20 both contain rectifier circuits, the first capacitor C1 can also filter out the harmonics present in the rectified DC power, making the DC power output to the first inverter circuit 30 smoother and more stable.

[0067] In conjunction with the raising and lowering of the pantograph, the DC power supply circuit 10 can have multiple switching states.

[0068] In one embodiment, when the pantograph is raised, the DC power supply circuit 10 is closed, and the load (e.g. the ventilation fan of the subway) is supplied with power by AC power, and when the pantograph is lowered, the DC power supply circuit 10 is opened, and the load (e.g. the ventilation fan of the subway) is supplied with power by DC power, and the output of the first inverter circuit 30 can have a short interruption when the power supply mode is changed, but the energy of the battery on the subway can be saved. It can be understood that, in order to protect the circuit from current impact, there is a first pre-charge circuit between the DC output and the DC power supply circuit, and a second pre-charge circuit between the AC output and the AC power supply circuit.

[0069] In another embodiment, regardless of whether the pantograph is raised or not, i.e. whether the AC output has an output or not, the DC power supply circuit 10 will be continuously opened, and the output of the first inverter circuit 30 will not be interrupted, but when the DC voltage output by the power supply is high, even if the AC output has an output, AC power will not be used to supply power to the subway. It should be noted that, since the voltage across the first capacitor in the current situation will not decrease when the AC power supply is lost, there is always a high voltage, so the second pre-charge circuit can be omitted, only the first pre-charge circuit is retained, and the pre-charge switch in the first pre-charge circuit only operates when the DC output is powered, at which time the service life of the relay as the pre-charge switch is greatly improved.

[0070] The frequency conversion inverter power supply for the subway includes an alternating current power supply circuit 20, a direct current power supply circuit 10, a first capacitor C1 and a first inverter circuit 30. The alternating current power supply circuit 20 includes a first diode rectifier circuit. The direct current power supply circuit 10 includes a second inverter circuit 110 and a second diode rectifier circuit 120. The input end of the first diode rectifier circuit is connected with an alternating current output end. The input end of the second inverter circuit 110 is connected with a direct current output end. The output end of the second inverter circuit 110 is connected with the input end of the second diode rectifier circuit 120. The output end of the first diode rectifier circuit and the output end of the second diode rectifier circuit 120 are both connected with the first capacitor C1, for outputting direct current to the first capacitor C1. The first capacitor C1 is connected with the input end of the first inverter circuit 30, for discharging to the first inverter circuit 30. The output end of the first inverter circuit 30 is connected with a load. As seen above, the direct current power supply circuit 10 and the alternating current power supply circuit 20 both charge the first capacitor C1, and then supply power to the subway through the first inverter circuit 30. When the direct current voltage at the output end of the alternating current power supply circuit 20 is higher than the direct current voltage at the output end of the direct current power supply circuit 10, the diode in the second diode rectifier circuit 120 is automatically cut off, and the circuit between the alternating current power supply circuit 20 and the first capacitor C1 is conducted. At this time, the three-phase alternating current is supplied to the subway. When the direct current voltage at the output end of the alternating current power supply circuit 20 is lower than the direct current voltage at the output end of the direct current power supply circuit 10, the diode in the first diode rectifier circuit is automatically cut off, and the circuit between the direct current power supply circuit 10 and the first capacitor C1 is conducted. At this time, the direct current is supplied to the subway. Therefore, when the output at the alternating current output end changes due to the lifting of the pantograph of the subway, the application can realize the smooth switching of the direct current and the alternating current through the reverse cut-off of the diode instead of the switching of the relay based on simple circuit elements, reduces the overall cost, and prolongs the service life of the circuit.

[0071] According to the above embodiment, in order to ensure the stability of the subway power supply, the utility model discloses a specific frequency conversion inverter power supply for the subway, and relative to the previous embodiment, the technical scheme is further described and optimized. Specifically,

[0072] The direct current output end outputs K1V direct current, and the alternating current output end outputs K2V three-phase alternating current. The second inverter circuit 110 includes a boost inverter circuit 111 and a resonance circuit 112, wherein K1 is less than K2.

[0073] In the embodiment, the direct current output end outputs K1V direct current, the alternating current output end outputs K2V alternating current, and K1 is less than K 2，To ensure that the DC voltage output by the DC power supply circuit 10 is close to the DC voltage output by the AC power supply circuit 20, the DC power input to the DC power supply circuit 10 needs to be boosted and inverted through the boost inverter circuit 111 and resonant circuit 112 in the second inverter circuit 110. This ensures that the final output voltage of the DC power supply circuit 10 is compatible with the output voltage of the AC power supply circuit, thus avoiding fluctuations in the AC power input to the load. It is understood that K1V and K2V are the specific values ​​of the DC and AC power, respectively. In one specific case, K1V can be 100V and K2V can be 380V, meaning the DC output terminal outputs 100V DC power and the AC output terminal outputs 380V AC power. In this case, the boost ratio of the second inverter circuit 110 can be 5, ensuring that the output voltage of the DC power supply circuit 10 is close to the output voltage of the AC power supply circuit 20.

[0074] In this embodiment, the resonant circuit 112 is key to the soft switching of the DC power supply circuit 10. Adjusting the inductance or capacitance values ​​in the resonant circuit 112 can also increase the circuit's transmission power. In one specific embodiment, such as... Figure 1 As shown, the resonant circuit 112 consists of a second capacitor C2 and a fourth inductor L4, which can be an external inductor. In another specific embodiment, the resonant circuit 112 does not use an external inductor, but is composed of the second capacitor C2 and the leakage inductance of the transformer section in the boost inverter circuit 111. The second capacitor C2 is directly connected to the input terminal of the second diode rectifier circuit 120, which saves more cost and volume. It can be understood that when an external inductor is used, the inductance in the resonant circuit 112 is equivalent to the sum of the external inductor and the leakage inductance of the transformer section.

[0075] As can be seen from the above, when the DC output terminal outputs K1V DC and the AC output terminal outputs K2V AC, the aforementioned K1V DC is boosted and inverted through the boost inverter circuit 111 and the resonant circuit 112 in the second inverter circuit 110. This makes the output voltage of the DC power supply circuit 10 similar to the output voltage of the AC power supply circuit 20 after rectification of the 380V AC, thus avoiding voltage fluctuations in the subway due to power supply mode switching and ensuring the stability of the subway power supply.

[0076] According to the above embodiments, in order to invert and boost DC power, this utility model discloses a specific frequency converter power supply for subways. Compared with the previous embodiment, this embodiment further explains and optimizes the technical solution. Specifically:

[0077] The boost inverter circuit 111 includes: a first switching transistor Q1, a second switching transistor Q2, a first inductor L1, a second inductor L2, and a third inductor L3;

[0078] The second end of the first switch tube Q1 is connected with the second end of the second switch tube Q2, and the common end thereof is used as the first input end of the second inverter circuit 110; the second end of the first inductor L1 is connected with the first end of the third inductor L3, and the common end thereof is used as the second input end of the second inverter circuit 110; the input end of the second inverter circuit 110 comprises the first input end of the second inverter circuit 110 and the second input end of the second inverter circuit 110.

[0079] The first end of the first inductor L1 is connected with the first end of the first switch tube Q1.

[0080] The first inductor L1 and the third inductor L3 are used as the low-voltage side of the transformer; the second inductor L2 is used as the high-voltage side of the transformer; and the two ends of the second inductor L2 are used as the output end of the second inverter circuit 110.

[0081] In the embodiment, the first switch tube Q1 and the second switch tube Q2 are connected at the two ends of the low-voltage side of the transformer, and the two switch tubes are alternately turned on and turned off. When the first switch tube Q1 is turned on, the second switch tube Q2 is turned off, and the direct current output from the direct current output end forms a loop through the first switch tube Q1 and the first inductor L1, and the current flows in the low-voltage side winding of the transformer. When the second switch tube Q2 is turned on, the first switch tube Q1 is turned off, and the direct current output from the direct current output end forms a loop through the second switch tube Q2 and the third inductor L3, and the current flows in the low-voltage side winding of the transformer, and the current direction is opposite to that when the first switch tube Q1 is turned on. According to the principle of electromagnetic induction, when the current flows in the low-voltage side winding of the transformer, the induced voltage is generated in the second inductor L2 of the high-voltage side of the transformer. The first inductor L1 and the third inductor L3 are of the same size.

[0082] As can be seen from the above, through the alternate turn-on and turn-off of the first switch tube Q1 and the second switch tube Q2, the high-voltage side of the transformer alternately generates induced voltages of opposite directions, so that the second inverter circuit 110 can invert the direct current and output a square wave voltage. At the same time, the transformer composed of the first inductor L1, the second inductor L2 and the third inductor L3 can step up the direct current, and the ratio of the first inductor L1, the third inductor L3 and the second inductor L2 of the transformer can be adjusted to adjust the step-up ratio.

[0083] According to the above embodiment, in order to reduce the switching loss and EMI, the utility model discloses a specific subway frequency conversion inverter power supply, relative to the last embodiment, the embodiment makes further description and optimization to the technical scheme. Specifically:

[0084] The resonance circuit 112 comprises a fourth inductor L4 and a second capacitor C2.

[0085] The first end of the second capacitor C2 is connected with the first end of the second inductor L2; and the second end of the second capacitor C2 is connected with the first end of the fourth inductor L4.

[0086] The second end of the second inductor L2 is the first output end of the second inverter circuit 110; the second end of the fourth inductor L4 is the second output end of the second inverter circuit 110; the output end of the second inverter circuit 110 comprises the first output end of the second inverter circuit 110 and the second output end of the second inverter circuit 110.

[0087] In the embodiment, the resonant circuit 112 is an LC circuit composed of an inductor and a capacitor, when the switch tubes in the boost inverter circuit 111 are alternately turned on, the fourth inductor L4 and the second capacitor C2 will generate oscillation of current and voltage, and the fourth inductor L4 and the second capacitor C2 jointly determine the resonant frequency, under the specific resonant frequency, the turn-on and turn-off of the switch tube are controlled, and the current will naturally decrease to a position close to zero, so that the switching can be performed at the moment when the current of the switch tube is the smallest, the zero-current turn-on and turn-off are realized, and the switching loss is reduced. It should be noted that the above-mentioned specific resonant frequency is the case that the switching frequency is slightly lower than the resonant frequency.

[0088] It can be understood that, by adjusting the parameters of the fourth inductor L4 and the second capacitor C2, the switch tube can be switched when the current is zero, and such switching mode avoids the voltage and current overlap in hard switching, and greatly reduces the EMI caused by sudden voltage and current.

[0089] As can be seen from the above, adjusting the resonant frequency to be greater than the switching frequency can realize the zero-current turn-on and zero-current turn-off of the switch tube, which not only reduces the switching loss when the switch tube switches the switching state, but also avoids the voltage and current overlap in hard switching, and effectively reduces the generated electromagnetic interference.

[0090] According to the above-mentioned embodiment, in order to realize the smooth conversion from direct current power supply for the subway to alternating current power supply for the subway, the utility model embodiment discloses a specific frequency conversion inverter power supply for the subway, compared with the previous embodiment, the technical scheme is further explained and optimized. Specifically:

[0091] The second diode rectifier circuit 120 is a single-phase bridge rectifier circuit.

[0092] It can be understood that, when the pantograph is raised, the pantograph is connected to the overhead contact line, due to the one-way conduction of the diode in the above-mentioned single-phase rectifier bridge, the alternating current output by the alternating current output end is rectified by the alternating current power supply circuit 20, and when the direct current voltage at the output end of the alternating current power supply circuit 20 is higher than the direct current voltage at the output end of the direct current power supply circuit 10, the diode in the above-mentioned single-phase rectifier bridge is reverse blocked, and the alternating current is supplied to the subway.

[0093] From the above, when the DC voltage of the output end of the AC power supply circuit 20 is higher than the DC voltage of the output end of the DC power supply circuit 10, the diode in the single-phase rectifier bridge is reversed off, and the subway is powered by AC power, realizing the smooth conversion from DC power to AC power for subway power supply.

[0094] According to the above embodiment, in order to realize the smooth conversion from AC power to DC power for subway power supply, the utility model discloses a specific subway variable frequency inverter power supply, relative to the last embodiment, the embodiment has made further description and optimization to the technical scheme. Specifically:

[0095] The first diode rectifier circuit is a three-phase bridge rectifier circuit.

[0096] It can be understood that, due to the unidirectional conductivity of the diode, when the DC voltage of the output end of the AC power supply circuit 20 is less than the DC voltage of the output end of the DC power supply circuit 10, the diode in the three-phase bridge rectifier circuit is reversed off, and the subway is powered by DC power.

[0097] From the above, when the DC voltage of the output end of the AC power supply circuit 20 is higher than the DC voltage of the output end of the DC power supply circuit 10, the diode in the single-phase rectifier bridge is reversed off, and the subway is powered by AC power, realizing the smooth conversion from DC power to AC power for subway power supply.

[0098] According to the above embodiment, in order to realize the smooth conversion from AC power to DC power for subway power supply, the utility model discloses a specific subway variable frequency inverter power supply, relative to the last embodiment, the embodiment has made further description and optimization to the technical scheme. Specifically:

[0099] The first inverter circuit 30 comprises: a third switch tube Q3, a fourth switch tube Q4, a fifth switch tube Q5, a sixth switch tube Q6, a seventh switch tube Q7 and an eighth switch tube Q8.

[0100] The first end of the third switch tube Q3, the first end of the fifth switch tube Q5 and the first end of the seventh switch tube Q7 are connected with each other, and the common end thereof is as a first input end of the first inverter circuit 30;

[0101] The second end of the fourth switch tube Q4, the second end of the sixth switch tube Q6 and the second end of the eighth switch tube Q8 are connected with each other, and the common end thereof is as a second input end of the first inverter circuit 30; the input end of the first inverter circuit 30 comprises the first input end of the first inverter circuit 30 and the second input end of the first inverter circuit 30;

[0102] The second end of the third switch tube Q3 is connected with the first end of the fourth switch tube Q4, and the common end thereof is as a first output end of the first inverter circuit 30;

[0103] The second end of the fifth switch tube Q5 is connected with the first end of the sixth switch tube Q6, and the common end is used as the second output end of the first inverter circuit 30;

[0104] The second end of the seventh switch tube Q7 is connected with the first end of the eighth switch tube Q8, and the common end is used as the third output end of the first inverter circuit 30;

[0105] The output end of the first inverter circuit 30 comprises the first output end of the first inverter circuit 30, the second output end of the first inverter circuit 30 and the third output end of the first inverter circuit 30.

[0106] In the embodiment, the first inverter circuit 30 is composed of six switch tubes, and the third switch tube Q3 to the eighth switch tube Q8 form a three-phase bridge arm structure.

[0107] As can be seen, by controlling the conduction and turn-off of the third switch tube Q3 to the eighth switch tube Q8, the direct current output during the discharge of the first capacitor C1 can be converted into alternating current.

[0108] According to the above embodiment, in order to supply power to the subway by alternating current when the pantograph rises, as shown, Figure 3 The utility model discloses a specific frequency conversion inverter power supply for subway, relative to the last embodiment, this embodiment has made further description and optimization to technical scheme.

[0109] Still include: singlechip, power supply chip and drive chip, for when detecting that alternating current output end outputs alternating current, stop to power supply chip output enable signal, to make direct current power supply circuit 10 stop to battery ask energy, when detecting that alternating current output end has no output, to power supply chip output enable signal, so that direct current power supply circuit 10 starts work;

[0110] The enable signal output end of the single-chip microcomputer is connected with the control end of the power supply chip, for outputting the enable signal to the power supply chip, and the three-phase input voltage sampling end of the single-chip microcomputer is connected with the alternating current output end, for detecting whether the alternating current output end has output.

[0111] The output end of the power supply chip is connected with the drive chip, for providing the PWM control signal to the drive chip.

[0112] The drive chip is connected with the control end of each switch tube in the second inverter circuit 110, for driving the second inverter circuit 110 to invert the direct current into alternating current.

[0113] It can be understood that only when the DC voltage at the output end of the AC power supply circuit 20 is continuously higher than the DC voltage at the output end of the DC power supply circuit 10, the diode in the second diode rectifier circuit 120 is reverse blocked, so that even if the pantograph is raised, the AC power supply will not be used when the battery voltage is high. In order to supply power to the subway by AC when the pantograph is raised, the output state of the DC power supply circuit 10 can be controlled by disconnecting the battery from the DC power supply circuit 10, but this method has slow response speed and the change of the input current state can cause instability of the DC power supply circuit 10. In this method, the relay as a pre-charge switch in the first pre-charge circuit is switched frequently, which still causes the decrease of the service life of the relay.

[0114] In this embodiment, when the single-chip microcomputer detects that there is an output at the output end of the AC power supply, it stops outputting the enable signal to the power supply chip, so that the power supply chip stops providing the PWM control signal to the drive chip. The control end of the switch tube in the second inverter circuit 110 is connected with the drive chip, and the drive chip controls the conduction state of the switch tube. At this time, the switch tube in the second inverter circuit 110 stops alternating conduction, the DC power supply circuit 10 stops working, the DC voltage at the output end of the DC power supply circuit 10 is zero, the diode in the second diode rectifier circuit 120 is reverse blocked, and the subway is powered by AC. When the single-chip microcomputer detects that there is no output at the output end of the AC power supply, it starts outputting the enable signal to the power supply chip, and the drive chip controls the switch tube in the second inverter circuit 110 to alternate conduction. At this time, the DC power supply circuit 10 starts working, and there is an output at its output end, and the DC voltage at the output end of the AC power supply is zero, the diode in the first diode rectifier circuit is reverse blocked, and the subway is powered by DC.

[0115] Therefore, the single-chip microcomputer can control whether the power supply chip works, thereby affecting the working state of the DC power supply circuit 10, by controlling the enable signal of the power supply chip. It should be noted that although the DC power supply circuit 10 stops drawing energy from the battery, the connection between the battery and the DC power supply circuit 10 is not disconnected. In this embodiment, the relay as a pre-charge switch in the first pre-charge circuit always maintains a closed state and does not have a switching state. Therefore, the service life is improved.

[0116] In this embodiment, the single-chip microcomputer can also sample and monitor the output current of the DC power supply circuit 10 and the output current of the subway frequency conversion inverter power supply through the third resistor R3, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6. In addition, the single-chip microcomputer samples and detects the output voltage of the subway frequency conversion inverter power supply by connecting with the output end of the first inverter circuit 30 through the sampling resistor.

[0117] From the above, the single-chip microcomputer can monitor the output of the AC output end, controls the power supply chip to supply power to the driving chip through the enable signal, so that when the pantograph is raised, the DC power supply circuit 10 stops demanding energy from the battery, the DC power supply circuit 10 does not work, the DC voltage of the output end is zero, and the diode in the second diode rectifier circuit 120 is reverse blocked, so that the AC supplies power to the subway.

[0118] According to the above embodiment, in order to protect the frequency conversion inverter power supply for the subway and avoid current impact, as shown in the utility model embodiment, the utility model discloses a specific frequency conversion inverter power supply for the subway, relative to the last embodiment, the embodiment has made further description and optimization to the technical scheme. Figure 3

[0119] The frequency conversion inverter power supply for the subway further comprises a first pre-charging circuit and a second pre-charging circuit, wherein the first pre-charging circuit comprises a first resistor R1, a first switch K1 and a third capacitor C3, and the second pre-charging circuit comprises a second resistor R2 and a second switch K2.

[0120] The first switch K1 and the second switch K2 are connected with the single-chip microcomputer and are used for controlling the pre-charging process.

[0121] The first switch K1 is connected with the first resistor R1 in parallel, and the input end of the second inverter circuit is connected with the DC output end through the first resistor R1.

[0122] The third capacitor C3 is connected between the input ends of the second inverter circuit 110.

[0123] The second switch K2 is connected with the second resistor R2 in parallel, and the output end of the first diode rectifier circuit is connected with the first capacitor C1 through the second resistor R2.

[0124] In the embodiment, the DC power supply circuit 10 is directly connected with the battery through the first pre-charging circuit, and once the pre-charging is completed, the DC power supply circuit 10 is no longer disconnected, and the AC power supply circuit 20 is connected with the first inverter circuit 30 through the second pre-charging circuit.

[0125] The pre-charging circuit comprises a pre-charging resistor, a pre-charging capacitor and a control switch, is a circuit for limiting the charging current when initially connecting the power supply and the load, and avoiding current impact. In many electronic devices and electrical systems, especially when the voltage of the power supply is relatively high or the capacitance of the load is relatively large, the pre-charging circuit plays a key role. When the pre-charging starts, the control switch is turned off, the power supply charges the load through the pre-charging resistor, and when the voltage of the capacitor approaches the voltage of the power supply, the control switch is turned on. During the whole pre-charging process, the pre-charging capacitor plays a buffering role, so that the voltage across the load slowly rises.

[0126] ​In the embodiment, the first resistor R1 and the second resistor R2 are pre-charging resistors, the third capacitor C3 is a pre-charging capacitor, and the first switch K1 and the second switch K2 are control switches.

[0127] It should be noted that the single-chip microcomputer can control the pre-charging process by controlling the switch state of the first switch K1 and the second switch K2. Figure 3 As shown in FIG. 5, the single-chip microcomputer monitors the capacitor voltage of the first capacitor C1 and the third capacitor C3 through the 110V voltage sampling circuit and the bus voltage sampling circuit, respectively, and automatically controls the first switch K1 or the second switch K2 to be closed when the capacitor voltage of the first capacitor C1 or the third capacitor C3 approaches the power supply voltage. In addition, the single-chip microcomputer can also monitor the battery voltage value in real time to prevent the input voltage of the direct current power supply circuit 10 from being overvoltage or the battery from being over-discharged to affect the battery life.

[0128] As can be seen from the above, the first pre-charging circuit and the second pre-charging circuit can avoid damage to the direct current power supply circuit 10 and the first inverter circuit 30 caused by current impact through the current limiting effect of the pre-charging resistor and the buffering effect of the pre-charging capacitor.

[0129] Based on the above embodiment, the utility model embodiment further discloses a subway power supply equipment, which comprises the subway frequency conversion inverter power supply described in the above embodiment. Since the subway power supply equipment comprises the subway frequency conversion inverter power supply, the subway power supply equipment also has the same technical effects as the subway frequency conversion inverter power supply.

[0130] The above description of disclosed embodiments enables a person skilled in the art to implement or use the utility model. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the utility model. Therefore, the utility model will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A frequency converter power supply for subway use, characterized in that, include: An AC power supply circuit, a DC power supply circuit, a first capacitor, and a first inverter circuit are provided; wherein the AC power supply circuit includes a first diode rectifier circuit; and the DC power supply circuit includes a second inverter circuit and a second diode rectifier circuit. The input terminal of the first diode rectifier circuit is connected to the AC output terminal; The input terminal of the second inverter circuit is connected to the DC output terminal, and the output terminal of the second inverter circuit is connected to the input terminal of the second diode rectifier circuit. The output terminals of the first diode rectifier circuit and the second diode rectifier circuit are both connected to the first capacitor to output DC power to the first capacitor. The first capacitor is connected to the input terminal of the first inverter circuit and is used to discharge to the first inverter circuit. The output terminal of the first inverter circuit is used to connect to the load.

2. The frequency converter power supply for subways according to claim 1, characterized in that, The DC output terminal outputs K1V of DC power, and the AC output terminal outputs K2V of three-phase AC power. The second inverter circuit includes a boost inverter circuit and a resonant circuit, wherein K1 is less than K2.

3. The frequency converter power supply for subways according to claim 2, characterized in that, The boost inverter circuit includes: a first switching transistor, a second switching transistor, a first inductor, a second inductor, and a third inductor; The second terminal of the first switching transistor is connected to the second terminal of the second switching transistor, and their common terminal serves as the first input terminal of the second inverter circuit; the second terminal of the first inductor is connected to the first terminal of the third inductor, and their common terminal serves as the second input terminal of the second inverter circuit; the input terminal of the second inverter circuit includes the first input terminal of the second inverter circuit and the second input terminal of the second inverter circuit. The first end of the first inductor is connected to the first end of the first switching transistor; The first inductor and the third inductor are the low-voltage side of the transformer; the second inductor is the high-voltage side of the transformer; and the two ends of the second inductor serve as the output terminals of the second inverter circuit.

4. The frequency converter power supply for subways according to claim 3, characterized in that, The resonant circuit includes: a fourth inductor and a second capacitor; The first terminal of the second capacitor is connected to the first terminal of the second inductor; the second terminal of the second capacitor is connected to the first terminal of the fourth inductor. The second end of the second inductor serves as the first output terminal of the second inverter circuit; the second end of the fourth inductor serves as the second output terminal of the second inverter circuit; the output terminal of the second inverter circuit includes the first output terminal and the second output terminal of the second inverter circuit.

5. The frequency converter power supply for subways according to claim 4, characterized in that, The second diode rectifier circuit is a single-phase bridge rectifier circuit.

6. The frequency converter power supply for subways according to claim 1, characterized in that, The first diode rectifier circuit is a three-phase bridge rectifier circuit.

7. The frequency converter power supply for subways according to claim 1, characterized in that, The first inverter circuit includes: a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, and an eighth switch; The first terminals of the third switch, the fifth switch, and the seventh switch are interconnected, and their common terminal serves as the first input terminal of the first inverter circuit. The second terminals of the fourth switch, the sixth switch, and the eighth switch are interconnected, and their common terminal serves as the second input terminal of the first inverter circuit. The input terminal of the first inverter circuit includes the first input terminal and the second input terminal of the first inverter circuit. The second end of the third switch is connected to the first end of the fourth switch, and their common end serves as the first output terminal of the first inverter circuit. The second terminal of the fifth switch is connected to the first terminal of the sixth switch, and their common terminal serves as the second output terminal of the first inverter circuit. The second terminal of the seventh switch is connected to the first terminal of the eighth switch, and their common terminal serves as the third output terminal of the first inverter circuit. The output terminals of the first inverter circuit include a first output terminal, a second output terminal, and a third output terminal.

8. The frequency converter power supply for subways according to claim 1, characterized in that, Also includes: The microcontroller, power chip, and driver chip are used to stop outputting an enable signal to the power chip when AC power is detected being output from the AC power output terminal, so that the DC power supply circuit stops drawing energy from the battery; and to output the enable signal to the power chip when no AC power is detected being output from the AC power output terminal, so that the DC power supply circuit can start working. The enable signal output terminal of the microcontroller is connected to the control terminal of the power chip and is used to output the enable signal to the power chip. The three-phase input voltage sampling terminal of the microcontroller is connected to the AC output terminal and is used to detect whether there is output at the AC output terminal. The output terminal of the power chip is connected to the driver chip and is used to input a PWM signal to the driver chip; The driver chip is connected to the control terminal of each switch in the second inverter circuit, and is used to drive the second inverter circuit to convert DC power into AC power.

9. The frequency converter power supply for subways according to claim 8, characterized in that, Also includes: A first pre-charging circuit and a second pre-charging circuit; wherein, the first pre-charging circuit includes a first resistor, a first switch and a third capacitor, and the second pre-charging circuit includes a second resistor and a second switch; Both the first switch and the second switch are connected to the microcontroller and are used to control the pre-charging process; The first switch is connected in parallel with the first resistor, and the input terminal of the second inverter circuit is connected to the DC output terminal through the first resistor; The third capacitor is connected between the input terminals of the second inverter circuit; The second switch is connected in parallel with the second resistor, and the output terminal of the first diode rectifier circuit is connected to the first capacitor through the second resistor.

10. A subway power supply device, characterized in that, Includes the frequency converter power supply for subways as described in any one of claims 1 to 9.

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