CN101976999A - Three-leg nine-switch inverter for driving double-alternating current motor - Google Patents

Abstract

A three-leg nine-switch inverter for driving dual AC motors. It includes a main circuit, a first encoder, a second encoder, a current detection circuit, a digital signal processor, a drive circuit and a pulse width modulation signal generator; the main circuit includes a DC power supply, a filter capacitor, 9 switching elements and the first 1. The second current transformer. The three-leg nine-switch inverter for driving dual AC motors of the present invention can use one inverter to simultaneously control two three-phase AC motors independently, since the number of switching elements in the inverter is nine, Compared with the prior art, there are three fewer, so the volume of the controller and the number of driving circuits can be reduced, so the cost can be effectively reduced. In addition, the inverter also has the advantages of reasonable structural design, high control precision, and strong practicability.

Description

Be used for double cross and flow motor-driven three brachium pontis, nine switching inverters

Technical field

The present invention relates to a kind of inverter, particularly relate to and a kind ofly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters.

Background technology

A lot of industrial applications such as the motor vehicle that drives such as wheel hub motor, industrial robot, mine, electric locomotive all need to realize the independent control of two or four alternating current machines.

Alternating current machine is normally driven by the DC-AC inverter of an AC power supply.The DC busbar voltage is supplied with inverter and is converted AC voltage to, is used to drive each phase of alternating current machine.Alternating current machine generally adopts three-phase structure.Microcontroller or digital signal processor are the typical elements that is used for control inverter, come to apply predetermined driving voltage as the switch element gate signal of power device in their control inverters to alternating current machine, general pulse-width modulation (PWM) signal that adopts, the switch element of employing is generally IGBT or MOSFET.When needs are controlled two alternating current machines separately, method commonly used at present has two kinds: a kind of is to dispose an inverter separately for every alternating current machine, promptly use two inverters, wherein every inverter all is three brachium pontis, comprise two switch elements in each brachium pontis, need 12 switch elements altogether.Because the volume of controller is bigger when adopting two inverters, and the number of inverse parallel diode, drive circuit is more, so cost is higher.Another method is to adopt an inverter to control two alternating current machines simultaneously, this moment, inverter was six brachium pontis, comprise two switch elements in each brachium pontis, six brachium pontis are divided into two groups, control an alternating current machine separately for every group, though be merged into the quantity and a cost that can reduce parts such as inverter casing, radiator because of inverter by two when adopting this method, and the volume of controller reduces to some extent, but because the number of switch element does not change, and the number of inverse parallel diode, drive circuit also reduces, so cost is still higher.

Summary of the invention

In order to address the above problem, the object of the present invention is to provide a kind of double cross that is used for that can effectively reduce cost to flow motor-driven three brachium pontis, nine switching inverters.

In order to achieve the above object, provided by the inventionly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters and comprise: major loop, the 1st encoder, the 2nd encoder, current detection circuit, digital signal processor, drive circuit and pulse-width signal generator; Wherein, three-phase brachium pontis and the 1st, the 2nd current transformer that major loop is formed by DC power supply, filtering capacitor, by 9 switch elements are formed, it has two three phase power output ports, be connected with the 2nd three phase electric machine with the 1st three phase electric machine respectively, and 1st, the 2nd current transformer is installed in respectively on above-mentioned two three phase power output ports, two output port is connected with two input ports of current detection circuit respectively, is used to detect the running current value of the 1st three phase electric machine and the 2nd three phase electric machine; The 1st encoder and the 2nd encoder are installed in respectively on the main shaft of the 1st three phase electric machine and the 2nd three phase electric machine, and two output port is connected with two input ports of digital signal processor respectively; Current detection circuit is the input interface circuit of the 1st, the 2 current transformer, and two input ports are connected with the 1st, the 2 current transformer respectively on it, and two output ports are connected with two input ports of digital signal processor respectively; Digital signal processor is the master controller of inverter, and its output port directly is connected with the pulse-width signal generator, and its input port is connected with the 2nd encoder and current detection circuit with the 1st encoder respectively; The pulse-width signal generator is the pwm pulse signal generating means, is connected between digital signal processor and the drive circuit; Drive circuit is the required gate drive circuit of switch element, is connected between pulse-width signal generator and the major loop.

Described major loop comprises: DC power supply, filter capacitor, 9 switch element UL, VL, WL, UM, VM, WM, UH, VH, WH and the 1st, the 2nd current transformer; Wherein filter capacitor is the power-type filtering capacitor, and it is pressed for dc bus provides galvanic current after the DC power supply parallel connection; 9 switch element UL, VL, WL, UM, VM, WM, UH, VH, WH form the three-phase bridge arm jointly, wherein switch element UL, UM, UH are composed in series U phase brachium pontis, switch element VL, VM, VH are composed in series V phase brachium pontis, switch element WL, WM, WH are composed in series W phase brachium pontis, and U, V, W three-phase brachium pontis all are directly parallel on the dc bus; Three phase windings of the 1st three phase electric machine are connected between switch element UH and UM, VH and VM, WH and the WM; Three phase windings of the 2nd three phase electric machine are connected between switch element UL and UM, VL and VM, WL and the WM; 1st, the 2nd current transformer is installed in respectively on the major loop on the connecting line of two three phase power output ports and the 1st three phase electric machine and the 2nd three phase electric machine.

Described switch element UL, VL, WL, UM, VM, WM, UH, VH, WH are IGBT or MOSFET device.

Described pulse-width signal generator comprises pulse-width modulation signal generating circuit, the 1st, the 2nd reference signal generator and carrier signal generator; Wherein pulse-width modulation signal generating circuit comprises the 1st, the 2nd comparator, the 1st, the 2nd inverter and OR circuit; Wherein the 1st, the 2nd comparator is a voltage comparator, be input to the positive input terminal of the 1st comparator after the 1st reference signal and the stack of the 1st shifted signal, be input to the positive input terminal of the 2nd comparator after the 2nd reference signal and the stack of the 2nd shifted signal, carrier signal is input to the negative input end of the 1st, the 2nd comparator respectively; The output of the 1st comparator is the output of the required pulse-width signal of the last brachium pontis arteries and veins be made up of switch element UH, VH, WH, the output of the 1st comparator is connected with the input of the 1st inverter simultaneously, and the output of the 1st inverter then is connected with an input of OR circuit; Another input of OR circuit is connected with the output of the 2nd comparator, and its output is the output of the required wide modulation signal of the middle brachium pontis arteries and veins be made up of switch element UM, VM, WM; The input of the 2nd inverter is connected with the output of the 2nd comparator, and its output is the output of the required pulse-width signal of the following brachium pontis be made up of switch element UL, VL, WL; 1st, the 2nd reference signal generator is controlled sine wave signal generator, and it can produce the 1st reference signal and the 2nd reference signal that is used to control the 1st three phase electric machine and the 2nd three phase electric machine under the control of digital signal processor; Carrier signal generator is controlled triangular signal generator based, and it can produce triangular signal under the control of digital signal processor, thereby provides carrier signal for the 1st, the 2nd comparator.

The model of described digital signal processor 7 is TMS320F28335.

Described the 1st encoder and the 2nd encoder are the photoelectric type pulse coder.

Provided by the inventionly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters and can simultaneously two three phase alternating current motors be controlled separately by enough inverters, because the number of switch element is 9 in the inverter, 3 have been reduced than prior art, so can reduce the volume of controller and the number of drive circuit, therefore can effectively reduce cost.In addition, this inverter also has reasonable in design, control precision height, advantage such as practical.

Description of drawings

Fig. 1 is used for double cross and flows motor-driven three brachium pontis, nine switching inverter major loop primary structure schematic diagrames for provided by the invention.

Fig. 2 is the operational mode schematic diagram that motor-driven three brachium pontis, nine switching inverter major loops are flowed in double cross that is used for shown in Fig. 1.

Fig. 3 is INV1 shown in Fig. 2 and INV2 gate pole pulse-width signal generating principle sequential chart.

Carrier signal and the reference waveform signal schematic diagram of Fig. 4 when the 1st carrier signal among Fig. 3 and the 2nd carrier signal being merged into a complete triangular signal.

Fig. 5 is used for double cross and flows motor-driven three brachium pontis, nine switching inverter pulse-width modulation signal generating circuit schematic diagrams for provided by the invention.

Fig. 6 is used for double cross and flows motor-driven three brachium pontis, nine switching inverters and form structural representation for provided by the invention.

Embodiment

In order to make purpose of the present invention, technical scheme clearer, the present invention is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only is used to explain the present invention, and be not used in qualification the present invention.

Fig. 1 is used for double cross and flows motor-driven three brachium pontis, nine switching inverter major loop primary structure schematic diagrames for provided by the invention.As shown in Figure 1, provided by the inventionly be used for double cross and flow motor-driven three brachium pontis, nine switching inverter major loops and mainly comprise: DC power supply E, filter capacitor C and 9 switch element UL, VL, WL, UM, VM, WM, UH, VH, WH; Wherein filter capacitor C is the power-type filtering capacitor, and it is pressed for dc bus AB provides galvanic current after DC power supply E parallel connection; 9 switch element UL, VL, WL, UM, VM, WM, UH, VH, WH are IGBT or MOSFET device, form the three-phase brachium pontis altogether, wherein switch element UL, UM, UH are composed in series U phase brachium pontis, switch element VL, VM, VH are composed in series V phase brachium pontis, switch element WL, WM, WH are composed in series W phase brachium pontis, and U, V, W three-phase brachium pontis all are directly parallel on the dc bus AB; Three phase windings of the 1st three phase electric machine 2 are connected between switch element UH and UM, VH and VM, WH and the WM; Three phase windings of the 2nd three phase electric machine 3 are connected between switch element UL and UM, VL and VM, WL and the WM.

Owing to adopted above-mentioned three brachium pontis, nine switch topology, each brachium pontis all contains three switch elements and two-way output on dc bus AB.Yet, be implemented in and drive two motors on the dc bus simultaneously independently, just must adopt the operational mode of timesharing control, promptly by the reasonable cooperation of 9 switch element switch motions, realize the timesharing control of the 1st three phase electric machine 2 and the 2nd three phase electric machine 3.The relative theory and the control method of two motor timesharing controls are described below by Fig. 2 and Fig. 3.

Fig. 2 is the operational mode schematic diagram that motor-driven three brachium pontis, nine switching inverter major loops are flowed in double cross that is used for shown in Fig. 1.As shown in Figure 2, the figure middle and upper part is divided into the pattern 1 that is used to drive the 1st three phase electric machine 2, and the top of brachium pontis is called INV1 in the pattern 1, the figure lower middle portion be used to drive the 2nd three phase electric machine 3 pattern 2, the lower part of brachium pontis is called INV2 in the pattern 2.INV1 comprises switch element UM, VM, WM, UH, VH, WH, and INV2 comprises switch element UM, VM, WM, UL, VL, WL.

Fig. 3 is INV1 shown in Fig. 2 and INV2 gate pole pulse-width signal generating principle sequential chart.As shown in Figure 3, the carrier signal that is used for pulse-width modulation has adopted unique waveform, be characterized in: when the pulse-width signal of the 1st three phase electric machine 2 is operated, the 2nd reference signal that is used to control the 2nd three phase electric machine 3 always is lower than the 2nd carrier signal that is used for 3 controls of the 2nd three phase electric machine, when the pulse-width signal of the 2nd three phase electric machine 3 was operated, the 1st reference signal that is used to control the 1st three phase electric machine 2 always was higher than the 1st carrier signal that is used for 2 controls of the 1st three phase electric machine.Therefore, when inverter drove the 1st three phase electric machine 2, switch element UL, VL, WL were in " opening " state, and when inverter drove the 2nd three phase electric machine 3, switch element UH, VH, WH were in " opening " state.In addition, the 1st carrier signal among Fig. 3 and the 2nd carrier signal can merge when producing gate electrode drive signals, and the carrier signal after the merging is a complete triangular signal.

Carrier signal and the reference waveform signal schematic diagram of Fig. 4 when the 1st carrier signal among Fig. 3 and the 2nd carrier signal being merged into a complete triangular signal.As shown in Figure 4, when the first half that is in triangular wave (be ordinate greater than zero part), calculate the pulse-width signal of INV1, when the latter half that is in triangular wave (being the minus part of ordinate), calculate the pulse-width signal of INV2.Make the U phase reference voltage level of INV1 be

The U phase reference voltage level of INV2 is

And

$V_{u1}^{\mathrm{ref}}=A_1\sin (2\mathrm{\π}{f}_{1}t+{\mathrm{\θ}}_1)$

$V_{u2}^{\mathrm{ref}}=A_2\sin (2\mathrm{\π}{f}_{2}t+{\mathrm{\θ}}_2)$

Wherein: A ₁, A ₂Be amplitude, f ₁, f ₂Be frequency, θ ₁, θ ₂Be phase place.

Unified modulation rate m is:

$m=\frac{V_{\mathrm{ref}}}{E/2}$

Wherein: E is a d-c bus voltage value.

When calculating pulse-width signal, the 1st shifted signal E/4 is added on the 1st reference signal, the 2nd shifted signal-E/4 is added on the 2nd reference signal, thereby the modulation rate of the 1st reference signal and the 2nd reference signal is respectively:

$m_{1u}=\frac{V_{u1}^{\mathrm{ref}}+E/4}{E/2}=\frac{V_{u1}^{\mathrm{ref}}}{E/2}+\frac{1}{2}$

$m_{2u}=\frac{V_{u2}^{\mathrm{ref}}-E/4}{E/2}=\frac{V_{u2}^{\mathrm{ref}}}{E/2}-\frac{1}{2}$

Can reach a conclusion thus: the reference voltage range of INV1 and INV2 is respectively:

$-E/4\≤V_{u1}^{\mathrm{ref}}\≤E/4$

$-E/4\≤V_{u2}^{\mathrm{ref}}\≤E/4$

Fig. 5 is used for double cross and flows motor-driven three brachium pontis, nine switching inverter pulse-width modulation signal generating circuit schematic diagrams for provided by the invention.As shown in Figure 5, described pulse-width modulation signal generating circuit comprises the 1st, the 2nd comparator U1, U2, the 1st, the 2nd inverter U3, U4 and OR circuit U5; Wherein the 1st, the 2nd comparator U1, U2 are voltage comparator, be input to the positive input terminal of the 1st comparator U1 after the 1st reference signal and the stack of the 1st shifted signal, be input to the positive input terminal of the 2nd comparator U2 after the 2nd reference signal and the stack of the 2nd shifted signal, carrier signal is input to the negative input end of the 1st, the 2nd comparator U1, U2 respectively; The output of the 1st comparator U1 is the output of the required pulse-width signal of the last brachium pontis be made up of switch element UH, VH, WH, the output of the 1st comparator U1 is connected with the input of the 1st inverter U3 simultaneously, and the output of the 1st inverter U3 then is connected with the input of OR circuit U5; Another input of OR circuit U5 is connected with the output of the 2nd comparator U2, and its output is the output of the required pulse-width signal of the middle brachium pontis be made up of switch element UM, VM, WM; The input of the 2nd inverter U4 is connected with the output of the 2nd comparator U2, and its output is the output of the required pulse-width signal of the following brachium pontis be made up of switch element UL, VL, WL.

The course of work of pulse-width modulation signal generating circuit shown in Figure 5 is: the 1st reference signal and the 1st shifted signal stack back generate the INV1 signal, this signal compares with carrier wave (triangular wave) signal again, when INV1 signal during greater than carrier signal, the drive signal of switch element UH, VH, WH is effective; The 2nd reference signal and the 2nd shifted signal stack back generates the INV2 signal, and this signal compares with carrier signal again, and when INV2 signal during less than carrier signal, the drive signal of switch element UL, VL, WL is effective; The drive signal of switch element UM, VM, WM is for carrying out the resulting result of logical "or" with the inversion signal of the drive signal of switch element UL, VL, WL again after the drive signal negate of switch element UH, VH, WH.

Fig. 6 is used for double cross and flows motor-driven three brachium pontis, nine switching inverters and form structural representation for provided by the invention.As shown in Figure 6, provided by the inventionly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters and comprise: major loop the 1, the 1st encoder the 4, the 2nd encoder 5, current detection circuit 6, digital signal processor (DSP) 7, drive circuit 8 and pulse-width signal generator 9; Wherein, major loop 1 has adopted the topological structure that motor-driven three brachium pontis, nine switching inverter major loops are flowed in double cross that is used for shown in Figure 1, it is by DC power supply E, filtering capacitor C, by 9 switch element UL, VL, WL, UM, VM, WM, UH, VH, the three-phase brachium pontis and the 1st that WH forms, the 2nd current transformer CT1, CT2 forms, it has two three phase power output ports, be connected with the 2nd three phase electric machine 3 with the 1st three phase electric machine 2 respectively, the and the 1st, the 2nd current transformer CT1 and CT2 are installed in respectively on above-mentioned two three phase power output ports, two output port is connected with two input ports of current detection circuit 6 respectively, is used to detect the running current value of the 1st three phase electric machine 2 and the 2nd three phase electric machine 3; The 1st encoder 4 and the 2nd encoder 5 are installed in respectively on the main shaft of the 1st three phase electric machine 2 and the 2nd three phase electric machine 3, and two output port is connected with two input ports of digital signal processor 7 respectively; Current detection circuit 6 is the input interface circuit of the 1st, the 2nd current transformer CT1 and CT2, two input ports link to each other with CT2 with the 1st, the 2nd current transformer CT1 respectively on it, and two output ports join mutually with two input ports of digital signal processor 7 respectively; Drive circuit 8 is switch element UL, VL, WL, UM, VM, WM, UH, VH, the required gate drive circuit of WH, is connected between pulse-width signal generator 9 and the major loop 1; Digital signal processor 7 is the master controller of inverter, be responsible for finishing the control and the computing of whole inverter, its output port directly is connected with pulse-width signal generator 9, its input port is connected with the 2nd encoder 5 and current detection circuit 6 with the 1st encoder 4 respectively, thereby forms the control closed loop of electric current loop and rotating speed/position ring; Pulse-width signal generator 9 is the pwm pulse signal generating means, effect is to produce the gate electrode drive signals (pulse-width signal) that is used to control three brachium pontis, nine switching inverter major loop switch elements provided by the invention, it mainly is by the pulse-width modulation signal generating circuit shown in Fig. 5 that its circuit is formed, the 1st, the 2nd reference signal generator and carrier signal generator are formed, wherein pulse-width modulation signal generating circuit is by the 1st, the 2nd comparator U1, U2, the 1st, the 2nd inverter U3, U4 and OR circuit U5 form, its effect is according to the 1st, relation between the 2nd reference signal and the carrier signal generates required pulse-width signal, the 1st, the 2nd reference signal generator is controlled sine wave signal generator, and it can produce the 1st reference signal and the 2nd reference signal that is used to control the 1st three phase electric machine 2 and the 2nd three phase electric machine 3 under the control of digital signal processor 7; Carrier signal generator is controlled triangular signal generator based, and it can produce triangular signal under the control of digital signal processor 7, thereby provides carrier signal for the 1st, the 2nd comparator U1 and U2; The course of work of pulse-width signal generator 9 is: at first send command signal by digital signal processor 7, the 1st, the 2nd reference signal generator and carrier signal generator produce corresponding the 1st reference signal according to the requirement of command signal, the 2nd reference signal and carrier signal, these signals enter among the pulse-width modulation signal generating circuit shown in Fig. 5, thereby generate required pulse-width signal, because whole inverter being used to of exporting drives the feature that the essential characteristic of the alternating current of three phase alternating current motor mainly depends on corresponding reference signal and carrier signal waveform, therefore, digital signal processor 7 can be by control the 1st reference signal, some feature of the 2nd reference signal and carrier signal is (as frequency, amplitude etc.) reach and control the 1st independently, the purpose of the 2nd three phase electric machine 2,3.In addition, described controlled sine wave signal generator and controlled triangular signal generator based this area typical component commonly used that is, the software of available multiple routine or hardware approach are realized, therefore introduce no longer in detail here.

Described the 1st encoder 4 and the 2nd encoder 5 are the photoelectric type pulse coder.

The model of described digital signal processor 7 is TMS320F28335.

Now be used for double cross and flow motor-driven three brachium pontis, the nine switching inverter courses of work and describe provided by the invention: described digital signal processor 7 is by the 1st encoder 4, the 2nd encoder 5 obtains the speed/positional signal of the 1st three phase electric machine 2 and the 2nd three phase electric machine 3, obtain the running current information of the 1st three phase electric machine 2 and the 2nd three phase electric machine 3 simultaneously by current detection circuit 6, produce through control pulse-width signal generator 9 after conversion and the computing then and be used to drive all switch element UL on the major loop 1, VL, WL, UM, VM, WM, UH, VH, the pulse-width signal of WH, and promote major loop 1 by drive circuit 8 and carry out work, come the 1st three phase electric machine 2 and the 2nd three phase electric machine 3 are carried out independent electric current and speed closed loop control with this.

Claims (6)

1. one kind is used for double cross and flows motor-driven three brachium pontis, nine switching inverters, it is characterized in that: describedly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters and comprise: major loop (1), the 1st encoder (4), the 2nd encoder (5), current detection circuit (6), digital signal processor (7), drive circuit (8) and pulse-width signal generator (9); Wherein, major loop (1) is by DC power supply (E), filtering capacitor (C), by 9 switch element (UL, VL, WL, UM, VM, WM, UH, VH, WH) the three-phase brachium pontis and the 1st of Zu Chenging, the 2nd current transformer (CT1, CT2) form, it has two three phase power output ports, be connected with the 2nd three phase electric machine (3) with the 1st three phase electric machine (2) respectively, the and the 1st, the 2nd current transformer (CT1) and (CT2) be installed in respectively on above-mentioned two three phase power output ports, two output port is connected with two input ports of current detection circuit (6) respectively, is used to detect the running current value of the 1st three phase electric machine (2) and the 2nd three phase electric machine (3); The 1st encoder (4) and the 2nd encoder (5) are installed in respectively on the main shaft of the 1st three phase electric machine (2) and the 2nd three phase electric machine (3), and two output port is connected with two input ports of digital signal processor (7) respectively; Current detection circuit (6) is the 1st, the 2 current transformer (CT1, input interface circuit CT2), two input ports are respectively with the 1st on it, (CT1's the 2nd current transformer CT2) links to each other, and two output ports join with two input ports of digital signal processor (7) simultaneously; Digital signal processor (7) is the master controller of inverter, and its output port directly is connected with pulse-width signal generator (9), and its input port is connected with the 2nd encoder (5) and current detection circuit (6) with the 1st encoder (4) respectively; Pulse-width signal generator (9) is the pwm pulse signal generating means, is connected between digital signal processor (7) and the drive circuit (8); Drive circuit (8) is the required gate drive circuit of switch element (UL, VL, W L, UM, VM, WM, UH, VH, WH), is connected between pulse-width signal generator (9) and the major loop (1).

2. according to claim 1ly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters, it is characterized in that: described major loop (1) comprising: and DC power supply (E), filter capacitor (C), 9 switch elements (UL, VL, WL, UM, VM, WM, UH, VH, WH) and the 1st, the 2nd current transformer (CT1, CT2); Wherein filter capacitor (C) is the power-type filtering capacitor, and it is pressed for dc bus (AB) provides galvanic current after DC power supply (E) parallel connection; 9 switch elements (UL, VL, WL, UM, VM, WM, UH, VH, WH) are formed the three-phase bridge arm jointly, wherein switch element (UL, UM, UH) is composed in series U phase brachium pontis, switch element (VL, VM, VH) is composed in series V phase brachium pontis, switch element (WL, WM, WH) is composed in series W phase brachium pontis, and U, V, W three-phase brachium pontis all are directly parallel on the dc bus (AB); Three phase windings of the 1st three phase electric machine (2) be connected to switch element (UH) and (UM), (VH) and (VM), (WH) and (WM) between; Three phase windings of the 2nd three phase electric machine (3) be connected to switch element (UL) and (UM), (VL) and (VM), (WL) and (WM) between; 1st, the 2nd current transformer (CT1) and (CT2) being installed in respectively on the connecting line of last two the three phase power output ports of major loop (1) and the 1st three phase electric machine (2) and the 2nd three phase electric machine (3).

3. according to claim 2ly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters, it is characterized in that: described switch element (UL, VL, WL, UM, VM, WM, UH, VH, WH) is IGBT or MOSFET device.

4. according to claim 1ly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters, it is characterized in that: described pulse-width signal generator (9) comprises pulse-width modulation signal generating circuit, the 1st, the 2nd reference signal generator and carrier signal generator; Wherein pulse-width modulation signal generating circuit comprise the 1st, the 2nd comparator (U1, U2), the 1st, the 2nd inverter (U3, U4) and OR circuit (U5); The the 1st, the 2nd comparator (U1 wherein, U2) be voltage comparator, be input to the positive input terminal of the 1st comparator (U1) after the 1st reference signal and the stack of the 1st shifted signal, be input to the positive input terminal of the 2nd comparator (U2) after the 2nd reference signal and the stack of the 2nd shifted signal, carrier signal is input to the negative input end of the 1st, the 2nd comparator (U1, U2) respectively; The output of the 1st comparator (U1) is the output of the required pulse-width signal of the last brachium pontis be made up of switch element (UH, VH, WH), the output of the 1st comparator (U1) is connected with the input of the 1st inverter (U3) simultaneously, and the output of the 1st inverter (U3) then is connected with an input of OR circuit (U5); Another input of OR circuit (U5) is connected with the output of the 2nd comparator (U2), and its output is the output of the required pulse-width signal of the middle brachium pontis be made up of switch element (UM, VM, WM); The input of the 2nd inverter (U4) is connected with the output of the 2nd comparator (U2), and its output is the output of the required pulse-width signal of the following brachium pontis be made up of switch element (UL, VL, WL); 1st, the 2nd reference signal generator is controlled sine wave signal generator, and it can produce the 1st reference signal and the 2nd reference signal that is used to control the 1st three phase electric machine (2) and the 2nd three phase electric machine (3) under the control of digital signal processor (7); Carrier signal generator is controlled triangular signal generator based, and it can produce triangular signal under the control of digital signal processor (7), thereby is that (U1 U2) provides carrier signal to the 1st, the 2nd comparator.

5. according to claim 1ly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters, it is characterized in that: the model of described digital signal processor (7) is TMS320F28335.

6. according to claim 1ly be used for double cross and flow motor-driven three brachium pontis, nine switching inverters, it is characterized in that: described the 1st encoder (4) and the 2nd encoder (5) are the photoelectric type pulse coder.

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