Common bus system for increasing power supply capacity and control method therefor

Abstract

The present disclosure relates to the technical field of power electronics rectification, and in particular to a common bus system for increasing power supply capacity and a control method therefor. To solve the problems of complex device structure, large volume, and high cost in existing devices for increasing power supply capacity, the disclosure provides a novel common bus system for increasing power supply capacity and a control method therefor. A first power supply input terminal is sequentially connected to a first contactor KM1, one end of a pre-charge circuit, a three-phase inductor, and a three-phase PWM rectifier circuit. A DC terminal of the three-phase PWM rectifier circuit is connected to a bus capacitor, so as to serve as a power supply output terminal connected to a load. A second power supply input terminal is sequentially connected to a second contactor KM2, a three-phase uncontrolled rectifier circuit, and one end of a third contactor KM3, and the other end of the third contactor KM3 is connected to the DC terminal of the three-phase PWM rectifier circuit. The present disclosure improves the output power capability of a single rectifier circuit.

Description

A common bus system for increasing power supply power and control method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on the Chinese patent application with application number 202311748866.6 and application date of December 19, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby incorporated into this disclosure by introduction. Technical Field

[0003] The present disclosure relates to the technical field of power electronic rectification, and in particular to a common bus system for increasing power supply power and a control method thereof. Background Art

[0004] In the field of power electronics rectification, there's often a need for a high-power, adjustable-output power supply system, typically employing diode or thyristor rectifiers. Currently, most power electronics power conversion devices serve as power sources. To increase the power level, higher-power power supplies, such as full-power PWM rectifiers, must be replaced. However, these devices are complex, bulky, and expensive.

[0005] Summary of the Invention

[0006] In order to solve the problems of complex equipment structure, large size and high cost in existing equipment for increasing power supply, the present disclosure provides a new common bus system for increasing power supply and a control method thereof.

[0007] The present disclosure is implemented by adopting the following technical solutions:

[0008] A common bus system for increasing power supply power includes a first power input terminal, a first contactor KM1, a pre-charging circuit, a three-phase PWM rectifier circuit, a bus capacitor, a second power input terminal, The second contactor KM2, the three-phase uncontrolled rectifier circuit, and the third contactor KM3, the first power input terminal is connected to one end of the first contactor KM1, the other end of the first contactor KM1 is connected to one end of the pre-charging circuit, the other end of the pre-charging circuit is connected to one end of the three-phase inductor, the other end of the three-phase inductor is connected to the AC end of the three-phase PWM rectifier circuit, the DC end of the three-phase PWM rectifier circuit is connected to the bus capacitor and then connected to the load as the output end of the power supply, the second power input terminal is connected to one end of the second contactor KM2, the other end of the second contactor KM2 is connected to the AC end of the three-phase uncontrolled rectifier circuit, the DC end of the three-phase uncontrolled rectifier circuit is connected to one end of the third contactor KM3, and the other end of the third contactor KM3 is connected to the DC end of the three-phase PWM rectifier circuit. The first power input terminal and the second power input terminal are both connected to the three-phase AC power supply as power input terminals.

[0009] The control method of the common bus system for increasing power supply power includes:

[0010] 1) The three-phase voltages of the three-phase AC power supply are u r ,u s ,u t The three-phase voltages are transformed by 3s / 2s (3s / 2s transformation is Clarke transformation, the three-phase stationary coordinate system is transformed into the two-phase stationary coordinate system), and the voltages in the two-phase stationary coordinate system are u α and u β , perform 2s / 2r transformation on the voltage in the two-phase stationary coordinate system (2s / 2r transformation is park transformation, the two-phase stationary coordinate system is transformed into the two-phase rotating coordinate system), and obtain the voltage in the two-phase rotating coordinate system as u d and u q , the voltage phase angle θ and voltage angular velocity ω are obtained through the phase-locked loop PLL;

[0011] The three-phase currents of the three-phase AC power supply are i r ,i s ,i t , where i r ,i t is the sampling value, i s is the calculated value; the calculation formula is as follows: s =-i r -i t , perform 3s / 2s transformation on the three-phase current, and obtain the currents in the two-phase stationary coordinate system as i α and i β , perform 2s / 2r transformation on the currents in the two-phase stationary coordinate system, and obtain the currents in the two-phase rotating coordinate system as i d and i q ;

[0012] Active power feedback quantity P of three-phase PWM rectifier circuit in =u α ×i α +u β ×i β ;

[0013] 2) The control method includes a function outer loop and a current inner loop, the function outer loop includes a voltage control loop and a voltage power control loop, and the current inner loop includes an active current inner loop and a reactive current inner loop;

[0014] Get the voltage given value u dcref and voltage feedback u dc ;

[0015] Voltage control loop: according to the voltage given quantity u dcref and voltage feedback udc After calculating the deviation between the two, the output of the voltage control loop U is obtained through the PI control module. out ;

[0016] The voltage power control loop firstly calculates the voltage given by u dcref and voltage feedback ud c Calculate the actual deviation u dcerr , when the actual deviation u dcerr Greater than the set deviation upper limit Δu dcerr When the power setting value P ref Gradually increase slowly; when the actual deviation u dcerr Less than the set deviation lower limit -Δu dcerr When the power setting value P ref Gradually decreases slowly; when the actual deviation u dcerr When setting the upper limit of deviation Δu dcerr and the set deviation lower limit -Δu dcerr When the power setting value P ref Keep unchanged, then according to the power given quantity P ref and active power feedback P in After calculating the deviation, the PI control module outputs P out ;

[0017] Get the reactive current given value i of the reactive current inner loop qref and current feedback i q , where the given quantity i of the inner loop of reactive current is qref =0, obtain the active current given value i of the active current inner loop dref and current feedback i d , where the active current given quantity i of the active current inner loop is dref To select U according to your needs out or P out The value after one of the functions is switched;

[0018] According to the current given quantity i of the reactive current inner loop qref and current feedback i q After calculating the deviation, the output of the reactive current loop i is obtained through the PI control module. qout ;

[0019] According to the current given quantity i of the active current inner loop dref and current feedback i d After calculating the deviation, the output of the active current loop i is obtained through the PI control module. dout ;

[0020] Calculate the given voltage, the given voltage includes u dref and u qref, and its specific calculation is as follows:

[0021] u dref =u d +i q ×ω×Li dout ,u qref =u q -i d ×ω×Li qout , where L is the inductance value;

[0022] will u dref 、u qref 、u dc and θ are sent to the SVPWM module, which generates corresponding PWM pulses to control the operation of the three-phase PWM rectifier circuit;

[0023] 3) When a three-phase uncontrolled rectifier circuit is used as the power supply, the second contactor KM2 and the third contactor KM3 are closed, and the three-phase uncontrolled rectifier circuit operates below its maximum output power limit, which is considered normal operation; when the load power requirement increases and exceeds the maximum power output limit of the three-phase uncontrolled rectifier circuit, the first contactor KM1 is closed, and the three-phase PWM rectifier circuit is started to supplement power to the bus. The supplementary control method adopts the control method of the voltage power control loop;

[0024] When a three-phase PWM rectifier circuit is used as the power supply and the power required by the load is less than the maximum output power limit of the three-phase PWM rectifier, the control method of the three-phase PWM rectifier circuit adopts voltage control loop control; when the power required by the load is greater than the maximum output power limit of the three-phase PWM rectifier circuit, the three-phase PWM rectifier operates in the voltage power control loop mode, and at the same time the second contactor KM2 and the third contactor KM3 are closed, and the three-phase uncontrolled rectifier circuit is put into operation.

[0025] This control method is used to increase the three-phase uncontrolled rectifier input AC voltage value, so that energy will continuously flow into the DC bus terminal, ensuring that the three-phase PWM rectifier output power plus the three-phase uncontrolled rectifier output power is approximately equal to the load power; the bus voltage is controlled within a reasonable range, that is, the voltage given quantity u dcre Near f.

[0026] In an optional embodiment of the present disclosure, a chopping circuit is further provided between the three-phase PWM rectifier circuit and the bus capacitor. When the bus voltage exceeds the safe voltage range that the equipment can withstand, the chopping function is started to protect the common bus system hardware.

[0027] The beneficial effects of the present disclosure are as follows: 1) achieving power complementarity between a three-phase PWM rectifier circuit and a three-phase uncontrolled rectifier circuit, improving the output power capacity of a single rectifier circuit, and achieving complementarity between PWM controlled rectifier and uncontrolled rectifier; 2) the maximum output that can be obtained is greater than the maximum power that the three-phase PWM rectifier circuit can withstand; 3) greatly reducing the use cost of the three-phase controlled power supply; 4) the control method in the present disclosure has good parameter robustness and does not require complex signal extraction, signal calculation and other steps, thereby improving its dynamic response characteristics; 5) compared with the use of two or more uncontrolled rectifier devices in parallel or a larger power uncontrolled rectifier device, the intermediate bus voltage is more stable; compared with the use of two or more PWM controlled rectifier devices in parallel or a larger power PWM rectifier device, the cost is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0029] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] FIG1 is a schematic diagram of a common bus system for increasing power supply power according to the present disclosure;

[0031] FIG2 is a control block diagram of a common bus system for increasing power supply power according to the present disclosure;

[0032] Figure 3 is a block diagram of the current inner loop control;

[0033] Figure 4 is a functional outer loop control block diagram.

[0034] In the figure: 1-first power input terminal, 2-precharging circuit, 3-three-phase PWM rectifier circuit, 4-bus capacitor, 5-load, 6-second power input terminal, 7-three-phase uncontrolled rectifier circuit, 8-three-phase inductor. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features therein can be combined with each other in the absence of conflict.

[0036] In the description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance. It should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, removable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms based on specific circumstances.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0038] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0039] As shown in Figure 1, a common bus system for increasing power supply power includes a first power input terminal 1, a first contactor KM1, a pre-charging circuit 2, a three-phase PWM rectifier circuit 3, a bus capacitor 4, a second power input terminal 6, a second contactor KM2, a three-phase uncontrolled rectifier circuit 7, and a third contactor KM3. The first power input terminal 1 is connected to one end of the first contactor KM1, the other end of the first contactor KM1 is connected to one end of the pre-charging circuit 2, the other end of the pre-charging circuit 2 is connected to one end of the three-phase inductor 8, and the other end of the three-phase inductor 8 is connected to the three-phase PWM rectifier circuit. 3, the DC end of the three-phase PWM rectifier circuit 3 is connected to the bus capacitor 4 and then connected to the load 5 as the output end of the power supply, the second power input terminal 6 is connected to one end of the second contactor KM2, the other end of the second contactor KM2 is connected to the AC end of the three-phase uncontrolled rectifier circuit 7, the DC end of the three-phase uncontrolled rectifier circuit 7 is connected to one end of the third contactor KM3, the other end of the third contactor KM3 is connected to the DC end of the three-phase PWM rectifier circuit 3, and the first power input terminal 1 and the second power input terminal 6 are both connected to the three-phase AC power supply as power input terminals.

[0040] As shown in Figures 2, 3, and 4, the control method for the common bus system for increasing power supply power includes:

[0041] 1) The three-phase voltages of the three-phase AC power supply are u r ,u s ,u t The three-phase voltages are transformed by 3s / 2s (3s / 2s transformation is Clarke transformation, the three-phase stationary coordinate system is transformed into the two-phase stationary coordinate system), and the voltages in the two-phase stationary coordinate system are u αand u β , perform 2s / 2r transformation on the voltage in the two-phase stationary coordinate system (2s / 2r transformation is park transformation, the two-phase stationary coordinate system is transformed into the two-phase rotating coordinate system), and obtain the voltage in the two-phase rotating coordinate system as u d and u q , the voltage phase angle θ and voltage angular velocity ω are obtained through the phase-locked loop PLL;

[0042] The three-phase currents of the three-phase AC power supply are i r ,i s ,i t , where i r ,i t is the sampling value, i s is the calculated value; the calculation formula is as follows: s =-i r -i t , perform 3s / 2s transformation on the three-phase current, and obtain the currents in the two-phase stationary coordinate system as i α and i β , perform 2s / 2r transformation on the currents in the two-phase stationary coordinate system, and obtain the currents in the two-phase rotating coordinate system as i d and i q ;

[0043] Active power feedback quantity P of three-phase PWM rectifier circuit 3 in =u α ×i α +u β ×i β ;

[0044] 2) The control method includes a function outer loop and a current inner loop, the function outer loop includes a voltage control loop and a voltage power control loop, and the current inner loop includes an active current inner loop and a reactive current inner loop;

[0045] Get the voltage given value u dcref and voltage feedback ud c ;

[0046] Voltage control loop: according to the voltage given quantity u dcref and voltage feedback ud c After calculating the deviation between the two, the output of the voltage control loop U is obtained through the PI control module. out ;

[0047] Voltage power control loop: First, according to the voltage given quantity u dcref and voltage feedback ud c Calculate the actual deviation u dcerr , when the actual deviation u dcerr Greater than the set deviation upper limit Δu dcerrWhen the power setting value P ref Gradually increase slowly; when the actual deviation u dcerr Less than the set deviation lower limit -Δu dcerr When the power setting value P ref Gradually decreases slowly; when the actual deviation u dcerr When setting the upper limit of deviation Δu dcerr and the set deviation lower limit -Δu dcerr When the power setting value P ref Keep unchanged, then according to the power given quantity P ref and active power feedback P in After calculating the deviation, the PI control module outputs P out ;

[0048] Get the reactive current given value i of the reactive current inner loop qref and current feedback i q , where the given quantity i of the inner loop of reactive current is qref =0, obtain the active current given value i of the active current inner loop dref and current feedback i d , where the active current given quantity i of the active current inner loop is dref To select U according to your needs out or P out The value after one of the functions is switched;

[0049] According to the current given quantity i of the reactive current inner loop qref and current feedback i q After calculating the deviation, the output of the reactive current loop i is obtained through the PI control module. qout ;

[0050] According to the current given quantity i of the active current inner loop dref and current feedback i d After calculating the deviation, the output of the active current loop i is obtained through the PI control module. dout ;

[0051] The given voltage includes u dref and u qref , and its specific calculation is as follows:

[0052] u dref =u d +i q ×ω×Li dout ,u qref =u q -i d ×ω×Li qout , where L is the inductance value;

[0053] will udref 、u qref 、u dc and θ are sent to the SVPWM module, which generates corresponding PWM pulses to control the operation of the three-phase PWM rectifier circuit 3;

[0054] 3) When the three-phase uncontrolled rectifier circuit 7 is used as the power supply, the second contactor KM2 and the third contactor KM3 are closed, and the three-phase uncontrolled rectifier circuit 7 operates below its maximum output power limit, which is considered normal operation; when the load 5 requires increased power and exceeds the maximum power output limit of the three-phase uncontrolled rectifier circuit 7, the first contactor KM1 is closed, and the three-phase PWM rectifier circuit 3 is started to supplement power to the bus. The supplementary control method adopts the control method of the voltage power control loop;

[0055] When the three-phase PWM rectifier circuit 3 is used as the power supply and the power required by the load 5 is less than the maximum output power limit of the three-phase PWM rectifier, the control method of the three-phase PWM rectifier circuit 3 adopts voltage control loop control; when the power required by the load 5 is greater than the maximum output power limit of the three-phase PWM rectifier circuit 3, the three-phase PWM rectifier operates in the voltage power control loop mode, and at the same time, the second contactor KM2 and the third contactor KM3 are closed, and the three-phase uncontrolled rectifier circuit 7 is put into operation.

[0056] This control method is used to increase the three-phase uncontrolled rectifier input AC voltage value, so that energy will continuously flow into the DC bus terminal, ensuring that the three-phase PWM rectifier output power plus the three-phase uncontrolled rectifier output power is approximately equal to the load 5 power; the bus voltage is controlled within a reasonable range, that is, the voltage given quantity u dcref nearby.

[0057] In specific implementation, a chopper circuit is further provided between the three-phase PWM rectifier circuit 3 and the bus capacitor 4. When the bus voltage exceeds the safe voltage range that the equipment can withstand, the chopper function is activated to protect the common bus system.

[0058] The above description is merely a specific embodiment of the present disclosure, which enables those skilled in the art to understand or implement the present disclosure. Although detailed descriptions have been made with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments, and they should all be covered by the scope of protection of the claims.

Claims

1. A common bus system for increasing power supply power, wherein: The present invention comprises a first power input terminal, a first contactor KM1, a pre-charging circuit, a three-phase PWM rectifier circuit, a bus capacitor, a second power input terminal, a second contactor KM2, a three-phase uncontrolled rectifier circuit, and a third contactor KM3. The first power input terminal is connected to one end of the first contactor KM1, the other end of the first contactor KM1 is connected to one end of the pre-charging circuit, the other end of the pre-charging circuit is connected to one end of the three-phase inductor, the other end of the three-phase inductor is connected to the AC end of the three-phase PWM rectifier circuit, the DC end of the three-phase PWM rectifier circuit is connected to the bus capacitor and then serves as the output end of the power supply and is connected to the load. The second power input terminal is connected to one end of the second contactor KM2, the other end of the second contactor KM2 is connected to the AC end of the three-phase uncontrolled rectifier circuit, the DC end of the three-phase uncontrolled rectifier circuit is connected to one end of the third contactor KM3, and the other end of the third contactor KM3 is connected to the DC end of the three-phase PWM rectifier circuit. The first power input terminal and the second power input terminal are both connected to the three-phase AC power supply as power input terminals.

2. A control method for a common bus system for increasing power supply power, implemented by the common bus system for increasing power supply power according to claim 1, wherein: include: 1) The three-phase voltages of the three-phase AC power supply are u r ,u s ,u t The three-phase voltage is transformed by 3s / 2s, and the voltages of the two-phase stationary coordinate system are u α and u β , perform 2s / 2r transformation on the voltage of the two-phase stationary coordinate system, and obtain the voltage of the two-phase rotating coordinate system as u d and u q , the voltage phase angle θ and voltage angular velocity ω are obtained through the phase-locked loop PLL; The three-phase currents of the three-phase AC power supply are i r ,i s ,i t , where i r ,i t is the sampling value, i s is the calculated value; the calculation formula is as follows: s =-i r -i t , perform 3s / 2s transformation on the three-phase current, and obtain the currents in the two-phase stationary coordinate system as i α and i β , perform 2s / 2r transformation on the currents in the two-phase stationary coordinate system, and obtain the currents in the two-phase rotating coordinate system as i d and i q ; Active power feedback quantity P of three-phase PWM rectifier circuit in =u α ×i α +u β ×i β ; 2) The control method includes a function outer loop and a current inner loop, the function outer loop includes a voltage control loop and a voltage power control loop, and the current inner loop includes an active current inner loop and a reactive current inner loop; Get the voltage given value u dcref and voltage feedback u dc ; Voltage control loop: according to the voltage given quantity u dcref and voltage feedback u dc After calculating the deviation between the two, the output of the voltage control loop U is obtained through the PI control module. out ; The voltage power control loop firstly calculates the voltage given by u dcref and voltage feedback u dc Calculate the actual deviation u dcerr , when the actual deviation u dcerr Greater than the set deviation upper limit Δu dcerr When the power setting value P ref Gradually increase slowly; when the actual deviation u dcerr Less than the set deviation lower limit -Δu dcerr When the power setting value P ref Gradually decreases slowly; when the actual deviation u dcerr When setting the upper limit of deviation Δu dcerr and the set deviation lower limit -Δu dcerr When the power setting value P ref Keep unchanged, then according to the power given quantity P ref and active power feedback P in After calculating the deviation, the PI control module outputs P out ; Get the reactive current given value i of the reactive current inner loop qref and current feedback i q , where the given quantity i of the inner loop of reactive current is qref =0, obtain the active current given value i of the active current inner loop dref and current feedback i d , where the active current given quantity i of the active current inner loop is dref To select U according to your needs out or P out The value after one of the functions is switched; According to the current given quantity i of the reactive current inner loop qref and current feedback i q After calculating the deviation, the output of the reactive current loop i is obtained through the PI control module. qout ; According to the current given quantity i of the active current inner loop dref and current feedback i d After calculating the deviation, the output of the active current loop i is obtained through the PI control module. dout ; The given voltage includes u dref and u qref , and its specific calculation is as follows: u dref = u d + i q × ω × L - i dout ,u qref = u q - i d × ω × L - i qout where L is the inductance value; will u dref 、u qref 、u dc and θ are sent to the SVPWM module, which generates corresponding PWM pulses to control the operation of the three-phase PWM rectifier circuit; 3) When a three-phase uncontrolled rectifier circuit is used as the power supply, the second contactor KM2 and the third contactor KM3 are closed, and the three-phase uncontrolled rectifier circuit operates below its maximum output power limit, which is considered normal operation; when the load power requirement increases and exceeds the maximum power output limit of the three-phase uncontrolled rectifier circuit, the first contactor KM1 is closed, and the three-phase PWM rectifier circuit is started to supplement power to the bus. The supplementary control method adopts the control method of the voltage power control loop; When a three-phase PWM rectifier circuit is used as the power supply and the power required by the load is less than the maximum output power limit of the three-phase PWM rectifier, the control method of the three-phase PWM rectifier circuit adopts voltage control loop control; when the power required by the load is greater than the maximum output power limit of the three-phase PWM rectifier circuit, the three-phase PWM rectifier operates in the voltage power control loop mode, and at the same time the second contactor KM2 and the third contactor KM3 are closed, and the three-phase uncontrolled rectifier circuit is put into operation.

3. A control method for a common bus system for increasing power supply power according to claim 2, wherein: A chopper circuit is also provided between the three-phase PWM rectifier circuit and the bus capacitor. When the bus voltage exceeds the safe voltage range that the equipment can withstand, the chopper function is activated.

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