阅读说明：本技术 一种电流源型电机驱动系统零电压开关及共模电压抑制方法 (zero-voltage switch and common-mode voltage suppression method for current source type motor driving system ) 是由 王政 徐阳 刘鹏程 程明 于 2019-07-30 设计创作，主要内容包括：本发明公开一种电流源型电机驱动系统零电压开关及共模电压抑制方法,包括：位于三相永磁同步电机侧的电机定子绕组端口,由电流源型逆变器馈电；电流源型逆变器直流侧与零电压开关辅助电路并联；零电压开关辅助电路包括两个串联的开关管二极管支路以及电容支路；电源侧斩波器与电压源并联；两个直流母线电感分别电源侧斩波器串联,另一端分别与零电压开关辅助电路并联；直流母线电感的电流由斩波器控制,转速由电流源型逆变器控制。本发明可以降低高频开关器件的dv/dt,减小系统的共模电压,抑制高频变换器的电磁干扰,同时软开关的加入提高了系统的效率,有利于提升系统的功率密度,并且减少变换器的散热成本。(the invention discloses a zero voltage switch and common mode voltage suppression method of a current source type motor driving system, which comprises the following steps: the motor stator winding port positioned on the side of the three-phase permanent magnet synchronous motor is fed by a current source type inverter; the direct current side of the current source type inverter is connected with the zero-voltage switch auxiliary circuit in parallel; the zero-voltage switch auxiliary circuit comprises two switching tube diode branches and a capacitor branch which are connected in series; the power supply side chopper is connected with a voltage source in parallel; the two direct current bus inductors are respectively connected in series with the power supply side chopper, and the other ends of the direct current bus inductors are respectively connected in parallel with the zero voltage switch auxiliary circuit; the current of the direct current bus inductor is controlled by a chopper, and the rotating speed is controlled by a current source type inverter. The invention can reduce dv/dt of the high-frequency switch device, reduce common-mode voltage of the system, inhibit electromagnetic interference of the high-frequency converter, and simultaneously, the addition of the soft switch improves the efficiency of the system, thereby being beneficial to improving the power density of the system and reducing the heat dissipation cost of the converter.)

1. a zero voltage switch and common mode voltage suppression method of a current source type motor driving system is characterized in that: the system comprises a motor stator winding port positioned on the side of a three-phase permanent magnet synchronous motor (1.7), and is fed by a current source type inverter (1.5); the three-phase output end of the current source type inverter (1.5) is connected with three capacitors (1.6) for filtering; two ends of the direct current side of the current source type inverter (1.5) are respectively connected with two direct current bus inductors (1.3) in series; the zero-voltage switch auxiliary circuit (1.4) is connected with the direct current side of the current source type inverter (1.5) in parallel; the power supply side chopper (1.2) is connected with the voltage source (1.1) in parallel; the direct current bus inductor (1.3) is connected with the power supply side chopper (1.2) in series; the zero-voltage switch auxiliary circuit (1.4) comprises two switch tubes and a diode which are connected in series and a buffer capacitor; the current of the current source type inverter (1.5) corresponding to the direct current bus inductor (1.3) is controlled by a chopper, the rotating speed of the three-phase permanent magnet synchronous motor (1.7) is controlled by the current source type inverter (1.5), and the control method comprises the following steps:

1) The bus current charges the buffer capacitor: when a switching period starts, a current vector corresponding to a current source type inverter (1.5) is a zero vector I7, all switching tubes on the side of the inverter are turned off at the moment, the switching tubes S3 and S4 of the auxiliary circuit are turned on, the voltage of the buffer capacitor is U2 which is far greater than zero due to the fact that the last switching period is finished, the diodes D3 and D4 are turned off, bus current charges the buffer capacitor C, and the voltage of the capacitor is gradually reduced;

2) The auxiliary circuit acts as a freewheel path: the voltage of the buffer capacitor C is reduced to zero, the diodes D3 and D4 are conducted, and the bus current flows through the auxiliary circuit (1.4);

3) the bus current charges the buffer capacitor: the zero vector I7 action of the current source type inverter (1.5) is finished, the current vector I2 starts to act, the auxiliary circuit switch tubes S3 and S4 are switched off, the voltage of the buffer capacitor is smaller than the voltage of the motor end, the bus current charges the buffer capacitor C through the diode, and the voltage of the direct current side of the current source type inverter (1.5) is gradually raised;

4) the inverter switching tube is conducted: the bus current charges the buffer capacitor C through the diode until the capacitor voltage is equal to the voltage of the motor terminal, and zero voltage of switching tubes Si1 and Si2 of the current source type inverter (1.5) is switched on;

5) the bus current charges the buffer capacitor: the zero vector I2 action of the current source type inverter (1.5) is finished, the switch tubes Si1 and Si2 are turned off, the current vector I1 starts to act, the voltage of the buffer capacitor is smaller than the voltage of the motor end, the bus current charges the buffer capacitor C through the diode, and the voltage of the direct current side of the current source type inverter (1.5) is gradually raised;

6) the inverter switching tube is conducted: the bus current charges the buffer capacitor C through the diode until the capacitor voltage is equal to the voltage of the motor terminal, and zero voltage of switching tubes Si1 and Si6 of the current source type inverter (1.5) is switched on;

7) The chopper diode is turned on: the switching tube of the chopper is turned off, the diode continues current, and the working states of the inverter and the auxiliary circuit are not changed.

2. The method for zero-voltage switching and common-mode voltage suppression of a current source motor driving system according to claim 1, wherein the control method of the current source inverter comprises the following steps:

a) The capacitance voltage Uabc and the electrical angle theta e of the filter capacitor are subjected to coordinate transformation to obtain a capacitance voltage d-axis component Ud and a capacitance voltage q-axis component Uq of the filter capacitor;

b) The capacitor voltage d-axis component Ud and the q-axis component Uq of the filter capacitor pass through a low-pass filter to obtain the steady-state component of the capacitor voltage, the electric angle theta e is differentiated to obtain the electric angular velocity omega e of the motor, and the steady-state current sum of the filter capacitor is obtained through calculation

c) the error between the given rotating speed n and the actual rotating speed n is obtained through a PI controller, a control scheme of zero d-axis current is given to the q-axis current, and the given d-axis current is zero;

d) the d-axis component Ud and the q-axis component Uq of the capacitor voltage pass through a high-pass filter to obtain high-frequency components Udh and Uqh of the capacitor voltage, the high-frequency components are multiplied by a virtual resistance coefficient kpv to obtain a value of virtual current, and the virtual resistance is used for consuming the quintuple harmonic of the motor winding current;

e) the method comprises the following steps that steady-state current and virtual resistance current of capacitors on d-axis and q-axis current setting and compensation are obtained to obtain final current setting, and a Cartesian coordinate system is converted into a polar coordinate system to obtain direct current setting and a trigger delay angle alpha of a current source type inverter;

f) The given direct current and the actual current value idc pass through a PI controller to obtain the duty ratio Ds of a chopper (1.2), the modulation degree ma of a current source type inverter is fixed, the triggering delay angle alpha of the current source type inverter is added with the actual motor electrical angle theta e to obtain the angle theta omega i of a reference vector of an SVM module, six-way switching pulses of the current source type inverter are generated by utilizing the modulation degree and the angle theta omega i, and the switching pulses of the chopper (1.2) are generated by utilizing the duty ratio Ds of the chopper.

Technical Field

the invention belongs to the field of motor driving, particularly relates to current source type frequency converter driving, and particularly relates to a zero voltage switch and a common mode voltage suppression method of a current source type motor driving system.

background

The losses of the power converter are divided into conduction losses and switching losses. For a majority carrier device, taking an IGBT as an example, there is a trailing effect of current when turning off, so current research is more focused on zero current turn-off; zero voltage turn-on is of more concern for minority carrier devices to reduce the overlap region of voltage current at the switching moment. The application of the soft switching technology can greatly reduce the switching loss of the device and improve the efficiency of the converter. The traditional soft switching technology of the motor driving system mainly aims at a voltage source type converter, the current source type soft switching technology is not researched much, and the defect of large loss of a current source type power converter can be effectively overcome by adopting the soft switching technology.

one of the most important problems of the high frequency converter is high frequency electromagnetic interference (EMI) noise generated by the fast switching voltage. The resulting Common Mode Voltage (CMV) is very harmful because it can compromise the system reliability and cause electromagnetic interference with the system's own auxiliary circuits and other electronic loads. Therefore, it is very important to solve the common mode voltage problem.

disclosure of Invention

the invention aims to overcome the defects and provides a zero voltage switch and a common-mode voltage suppression method of a current source type motor driving system, wherein the motor is fed by a current source type power converter, so that the reliability and fault tolerance of the motor driving system are improved; by applying the soft switching technology, the switch of the current source type inverter is flexible, the electromagnetic interference is reduced, the efficiency of a motor driving system is improved, the peak value of the common mode voltage of the system is reduced through a common mode voltage suppression strategy, and the electromagnetic performance of the system is improved.

In order to achieve the above object, the present invention provides a zero voltage switch and a common mode voltage suppression method for a current source type motor driving system, the current source type motor driving system includes:

the motor stator winding port positioned on the side of the three-phase permanent magnet synchronous motor is fed by a current source type inverter;

The three-phase output end of the current source type inverter is connected with three capacitors for filtering;

Two ends of the direct current side of the current source type inverter are respectively connected with two direct current bus inductors in series;

The zero-voltage switch auxiliary circuit is connected with the direct current side of the current source type inverter in parallel;

The power supply side chopper is connected with a voltage source in parallel;

the direct-current bus inductor is connected with the power supply side chopper in series;

the zero-voltage switch auxiliary circuit comprises two switch tubes, a diode and a buffer capacitor which are connected in series;

The current of the current source type inverter corresponding to the direct current bus inductor is controlled by the chopper.

The rotating speed of the three-phase permanent magnet synchronous motor is controlled by a current source type inverter.

the specific control method comprises the following steps:

for simplicity of analysis, three current vectors acting on the current source inverter in one switching cycle are I1, I2 and I0 respectively, the input voltages corresponding to the current source inverter are U1, U2 and U0, and the current vector switching flow chart is shown in fig. 4 by changing the acting sequence of the current vectors so that U1> U2> U0.

the specific operation of the soft switching in one switching cycle is as follows, and it is not assumed that the current source inverter operates in the first sector, and the current flow path is as shown in fig. 2.

1) State 0: bus current charges buffer capacitor

when the switching period starts, the current vector corresponding to the current source type inverter is a zero vector I7, all the switching tubes on the inverter side are turned off at the moment, and the auxiliary circuit switching tubes S3 and S4 are turned on. When the last switching period is finished, the voltage of the buffer capacitor is U2 and is far larger than zero, the diodes D3 and D4 are cut off, the bus current charges the buffer capacitor C, and the voltage of the capacitor is gradually reduced;

2) State 1: auxiliary circuit as freewheel path

The voltage of the buffer capacitor C is reduced to zero, the diodes D3 and D4 are conducted, and the bus current flows through the auxiliary circuit;

3) state 2: bus current charges buffer capacitor

The zero vector I7 action of the current source type inverter is finished, the current vector I2 action is started, the auxiliary circuit switch tubes S3 and S4 are turned off, the voltage of the buffer capacitor is smaller than the voltage of the motor end, the bus current charges the buffer capacitor C through the diode, and the voltage of the direct current side of the current source type inverter is gradually raised;

4) State 3: inverter switching tube conduction

the bus current charges the buffer capacitor C through the diode until the capacitor voltage is equal to the voltage of the motor terminal, and zero voltage of switching tubes Si1 and Si6 of the current source type inverter is switched on;

5) State 2: bus current charges resonant capacitor

the zero vector I2 action of the current source type inverter is finished, the current vector I1 action is started, the switching tubes Si1 and Si2 are switched off, the voltage of the buffer capacitor is smaller than the voltage of the motor end, the bus current charges the buffer capacitor C through the diode, and the voltage of the direct current side of the current source type inverter is gradually raised;

6) And 4: inverter switching tube conduction

the bus current charges the buffer capacitor C through the diode until the capacitor voltage is equal to the voltage of the motor terminal, and zero voltage of switching tubes Si1 and Si6 of the current source type inverter is switched on;

7) and state 5: chopper diode conduction

The switching tube of the chopper is turned off, the diode continues current, and the working states of the inverter and the auxiliary circuit are not changed;

the working principle of the auxiliary circuit common-mode voltage suppression is as follows:

Table 1 shows common-mode voltages corresponding to respective switching states of the conventional current source inverter, and it can be found that the common-mode voltage corresponding to the zero current vector is a phase voltage, and the common-mode voltage corresponding to the non-zero vector is half of the phase voltage. The invention introduces the auxiliary circuit, can realize soft switching, and simultaneously, the auxiliary circuit (1.4) is used for directly replacing a zero current vector on the inverter side, thereby inhibiting the common mode voltage, and the common mode voltage corresponding to each switching state after inhibition is shown in table 2.

Further, the control method of the current source type inverter is as follows:

1) the capacitance voltage Uabc and the electrical angle theta e of the filter capacitor are subjected to coordinate transformation to obtain a capacitance voltage d-axis component Ud and a capacitance voltage q-axis component Uq of the filter capacitor;

2) The capacitor voltage d-axis component Ud and the q-axis component Uq of the filter capacitor pass through a low-pass filter to obtain the steady-state component of the capacitor voltage, the electric angle theta e is differentiated to obtain the electric angular velocity omega e of the motor, and the steady-state current sum of the filter capacitor is obtained through calculation

3) The error between the given rotating speed n and the actual rotating speed n is obtained through a PI controller, a control scheme of zero d-axis current is given to the q-axis current, and the given d-axis current is zero;

4) The d-axis component Ud and the q-axis component Uq of the capacitor voltage pass through a high-pass filter to obtain high-frequency components Udh and Uqh of the capacitor voltage, the high-frequency components are multiplied by a virtual resistance coefficient kpv to obtain a value of virtual current, and the virtual resistance is used for consuming the quintuple harmonic of the motor winding current;

5) The method comprises the following steps that steady-state current and virtual resistance current of capacitors on d-axis and q-axis current setting and compensation are obtained to obtain final current setting, and a Cartesian coordinate system is converted into a polar coordinate system to obtain direct current setting and a trigger delay angle alpha of a current source type inverter;

6) the given direct current and the actual current value idc of the direct current pass through a PI controller to obtain the duty ratio Ds of a chopper, the modulation degree ma of a current source type inverter is fixed, the triggering delay angle alpha of the current source type inverter is added with the actual motor electrical angle theta e to obtain the angle theta omega i of the reference vector of the SVM module, six-path switching pulses of the current source type inverter are generated by utilizing the modulation degree and the angle theta omega i, and the switching pulses of the chopper are generated by utilizing the duty ratio Ds of the chopper.

has the advantages that:

the invention can reduce dv/dt of the high-frequency switch device, reduce common-mode voltage of the system, inhibit electromagnetic interference of the high-frequency converter, and simultaneously, the addition of the soft switch improves the efficiency of the system, thereby being beneficial to improving the power density of the system and reducing the heat dissipation cost of the converter.

drawings

FIG. 1 is a main circuit topology;

FIG. 2 is a diagram of the current flow path during a switching cycle;

FIG. 3 is a diagram of terminal voltage versus current vector;

FIG. 4 is a flow of current vector order of action selection;

FIG. 5 is a control system block diagram;

FIG. 6 is a converter common mode voltage;

fig. 7 is a diagram of a single cycle switching pulse in sector I.

Detailed Description

the technical scheme of the invention is explained in detail in the following with the accompanying drawings.

as shown in fig. 1 to 7, the present invention discloses a zero voltage switch and a common mode voltage suppression method for a current source type motor driving system, wherein the current source type motor driving system comprises:

a motor stator winding port positioned on the 1.7 side of the three-phase permanent magnet synchronous motor is fed by a current source type inverter 1.5;

The three-phase output end of the current source type inverter 1.5 is connected with three capacitors 1.6 for filtering;

two ends of the direct current side of the current source type inverter 1.5 are respectively connected with two direct current bus inductors 1.3 in series;

The zero voltage switch auxiliary circuit 1.4 is connected in parallel with the direct current side of the current source type inverter 1.5;

the power supply side chopper 1.2 is connected with a voltage source 1.1 in parallel;

The direct-current bus inductor 1.3 is connected with the power supply side chopper 1.2 in series;

the zero-voltage switch auxiliary circuit comprises two switch tubes, a diode and a buffer capacitor which are connected in series;

the current of the current source type inverter 1.5 corresponding to the direct current bus inductor 1.3 is controlled by a chopper.

the rotating speed of the three-phase permanent magnet synchronous motor 1.7 is controlled by a current source type inverter 1.5.

the zero voltage switch and common mode voltage suppression method comprises the following steps:

For simplicity of analysis, the three current vectors acting on the current source inverter 1.5 in one switching cycle are I1, I2 and I0 respectively, the input voltages corresponding to the current source inverter are U1, U2 and U0, and the current vector switching flow chart is shown in fig. 4 by changing the acting sequence of the current vectors so that U1> U2> U0.

The specific operation of the zero-voltage switch in one switching cycle is as follows, and it is not assumed that the current source inverter 1.5 operates in the first sector, and the current flow path is as shown in fig. 2.

1) State 0: bus current charges buffer capacitor

when the switching period starts, the current vector corresponding to the current source type inverter 1.5 is a zero vector I7, at this time, all the switching tubes on the inverter side are turned off, and the auxiliary circuit switching tubes S3 and S4 are turned on. When the last switching period is finished, the voltage of the buffer capacitor is U2 and is far larger than zero, the diodes D3 and D4 are cut off, the bus current charges the buffer capacitor C, and the voltage of the capacitor is gradually reduced;

2) State 1: auxiliary circuit as freewheel path

the voltage drop of the buffer capacitor C is zero, the diodes D3 and D4 are conducted, and the bus current flows through the auxiliary circuit 1.4;

3) state 2: bus current charges buffer capacitor

the zero vector I7 action of the current source type inverter 1.5 is finished, the current vector I2 starts to act, the auxiliary circuit switch tubes S3 and S4 are turned off, the voltage of the buffer capacitor is smaller than the voltage of the motor end, the bus current charges the buffer capacitor C through the diode, and the voltage of the direct current side of the current source type inverter 1.5 is gradually raised;

4) State 3: inverter switching tube conduction

the bus current charges the buffer capacitor C through the diode until the capacitor voltage is equal to the voltage of the motor terminal, and zero voltage of switching tubes Si1 and Si6 of the current source type inverter 1.5 is switched on;

5) State 2: bus current charges resonant capacitor

The zero vector I2 action of the current source type inverter 1.5 is finished, the current vector I1 starts to act, the switch tubes Si1 and Si2 are turned off, the voltage of the buffer capacitor is smaller than the voltage of the motor end, the bus current charges the buffer capacitor C through the diode, and the voltage of the direct current side of the current source type inverter 1.5 is gradually raised;

6) and 4: inverter switching tube conduction

the bus current charges the buffer capacitor C through the diode until the capacitor voltage is equal to the voltage of the motor terminal, and zero voltage of switching tubes Si1 and Si2 of the current source type inverter 1.5 is switched on;

7) and state 5: chopper diode conduction

The switching tube of the chopper is turned off, the diode continues current, and the working states of the inverter and the auxiliary circuit are not changed;

the working principle of the auxiliary circuit 1.4 common mode voltage rejection is as follows:

table 1 shows common-mode voltages corresponding to respective switching states of the conventional current source inverter, and it can be found that the common-mode voltage corresponding to the zero current vector is a phase voltage, and the common-mode voltage corresponding to the non-zero vector is half of the phase voltage. The invention introduces the auxiliary circuit, can realize soft switching, and simultaneously, the auxiliary circuit 1.4 is used for directly connecting to replace a zero current vector on the inverter side, thereby inhibiting the common mode voltage, and the common mode voltage corresponding to each switching state after inhibition is shown in table 2.

TABLE 1 conventional Current Source Current vector, switch State and its modulus Voltage

TABLE 2 improved Current vector of Current sources, switch State and their modulus voltages

the control method of the current source type inverter comprises the following steps:

1) The capacitance voltage Uabc and the electrical angle theta e of the filter capacitor are subjected to coordinate transformation to obtain a capacitance voltage d-axis component Ud and a capacitance voltage q-axis component Uq of the filter capacitor;

2) the capacitor voltage d-axis component Ud and the q-axis component Uq of the filter capacitor pass through a low-pass filter to obtain the steady-state component of the capacitor voltage, the electric angle theta e is differentiated to obtain the electric angular velocity omega e of the motor, and the steady-state current sum of the filter capacitor is obtained through calculation

3) The error between the given rotating speed n and the actual rotating speed n is obtained through a PI controller, a control scheme of zero d-axis current is given to the q-axis current, and the given d-axis current is zero;

4) the d-axis component Ud and the q-axis component Uq of the capacitor voltage pass through a high-pass filter to obtain high-frequency components Udh and Uqh of the capacitor voltage, the high-frequency components are multiplied by a virtual resistance coefficient kpv to obtain a value of virtual current, and the virtual resistance is used for consuming the quintuple harmonic of the motor winding current;

5) the method comprises the following steps that steady-state current and virtual resistance current of capacitors on d-axis and q-axis current setting and compensation are obtained to obtain final current setting, and a Cartesian coordinate system is converted into a polar coordinate system to obtain direct current setting and a trigger delay angle alpha of a current source type inverter;

6) the given direct current and the actual current value idc of the direct current pass through a PI controller to obtain a duty ratio Ds of a chopper 1.2, the modulation degree ma of a current source type inverter is fixed, the triggering delay angle alpha of the current source type inverter and the actual motor electrical angle theta e are added to obtain an angle theta omega i of a reference vector of an SVM module, six-way switching pulses of the current source type inverter are generated by utilizing the modulation degree and the angle theta omega i, and the switching pulses of the chopper 1.2 are generated by utilizing the duty ratio Ds of the chopper.

although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.