KR20230159719A - Active short circuit control apparatus of electric motor driving system and its method - Google Patents

Abstract

The present invention relates to an active short-circuit control device and method for an electric motor drive system, comprising: a drive motor connected to a vehicle axle to provide driving force; a drive motor system that controls the drive motor and operates an active short circuit depending on whether a safety state of the drive motor system is requested; And when the active short circuit is operated, a freewheeling comparison value for stabilizing the drive motor system is selected and generated using current information and angle information of the drive motor depending on whether the active short circuit is in a transient state. By including an active short-circuit current stabilizer that outputs to the drive motor system, overcurrent and vibration current can be suppressed by reducing the size of the peak phase current and shortening the vibration time.

Description

Active short circuit control device and method of electric motor driving system {ACTIVE SHORT CIRCUIT CONTROL APPARATUS OF ELECTRIC MOTOR DRIVING SYSTEM AND ITS METHOD}

The present invention controls the output of freewheeling between active short circuit operations for a very short period of time in order to reduce overcurrent and vibration current that occur in a transient state during active short circuit operation in an electric motor drive system, thereby reducing the size of the peak phase current. It relates to an active short-circuit control device and method for an electric motor drive system that can suppress overcurrent and vibration current by shortening the vibration time.

As is well known, as the risk from the climate crisis increases, many countries around the world are preparing for a carbon-neutral society, and the transportation industry centered on existing internal combustion engines is being greatly affected.

A major characteristic of this change in the future transportation industry is the active use of carbon-free electric motors. Not only are cars and airplanes using existing internal combustion engines being converted to electric vehicles and airplanes using highly efficient electric motor systems. , the applications mentioned above require higher reliability, higher efficiency, and higher power density than the electric motors used in existing industries.

Therefore, permanent magnet synchronous motors (PMSM) with high efficiency and high power density are expected to be widely used in the future transportation industry.

Meanwhile, functional safety has recently become increasingly important as a standard that must be complied with in the driving system of electric vehicles. This standard sets safety standards to prevent accidents caused by faults in the electrical and electronic systems of automobile parts. This means that a functional safety grade is assigned by analyzing the impact of each component on the overall system, and this grade is referred to as ASIL (Automotive Safety Integrity Level).

These ASIL grades range from QM (quality management) to ASIL D, and the grade currently given to drive motors and inverter systems in electric vehicle systems is ASIL C/D, which is a very high level. For example, in the case of a single point fault, it must have a high fault coverage ratio of 97-99%.

In order to respond to functional safety as described above, a safe state must be defined in the electric vehicle drive system. When a dangerous error is detected in the electric vehicle drive system, the system is placed in a normal state to comply with the defined safety goal. A transition occurs, and this is called a safe state.

Figures 1 and 2 are diagrams illustrating two safety states of a conventional permanent magnet synchronous motor. Figure 1 shows a freewheeling state in which all switches are turned off, and the energy stored in the motor core is transferred to the IGBT. The DC link voltage can be charged by energizing the freewheeling diode.

In addition, Figure 2 shows a low-side active short circuit (ASC) in which all switches on the lower side of the inverter are turned on. In this case, the current of the motor is You can see that there is no flow at all with the inverter's DC link voltage, which is the biggest advantage of the active short circuit algorithm. However, there is a problem in that when the active short circuit operates, the output voltage from the inverter becomes 0, and current control is no longer possible.

Therefore, the current of the motor can be determined by the back electromotive force voltage and the initial current of the motor, the response of the current can change depending on the motor speed, and overcurrent and vibration current can occur in the transient state of the active short circuit. There is a problem.

1. Korean Patent Publication No. 10-2017-0005414 (published on January 13, 2017)

The present invention controls the output of freewheeling between active short circuit operations for a very short period of time in order to reduce overcurrent and vibration current that occur in a transient state during active short circuit operation in an electric motor drive system, thereby reducing the size of the peak phase current. The objective is to provide an active short-circuit control device and method for an electric motor drive system that can suppress overcurrent and vibration current by shortening the vibration time.

The purposes of the embodiments of the present invention are not limited to the purposes mentioned above, and other purposes not mentioned will be clearly understood by those skilled in the art from the description below. .

According to one aspect of the present invention, a drive motor connected to the vehicle axis to provide driving force; a drive motor system that controls the drive motor using an active short circuit and operates the active short circuit depending on whether a safety state of the drive motor system is requested; And when the active short circuit is operated, a freewheeling comparison value for stabilizing the drive motor system is selected and generated using current information and angle information of the drive motor depending on whether the active short circuit is in a transient state. An active short circuit control device for an electric motor drive system including an active short circuit current stabilizer outputting to the drive motor system may be provided.

In addition, according to one aspect of the present invention, the driving motor system includes a motor controller that selects and controls a steady state output or a safe state output depending on whether a stable state is requested, and the motor controller includes the current and A motor control unit that controls torque and outputs a comparison value for driving control of the drive motor in a normal state; In the normal state, the comparison value output from the motor control unit is transmitted, and when the safety state of the driving motor system is requested, it operates as an active short circuit and receives the freewheeling comparison value output from the active short circuit current stabilizer. a switching unit that transmits; and a PWM generator that generates and outputs a PWM signal for driving control of the drive motor using a carrier wave and the comparison value or freewheeling comparison value. An active short-circuit control device for an electric motor drive system comprising a. there is.

In addition, according to one aspect of the present invention, the active short circuit current stabilizer converts the a-phase current, b-phase current, and c-phase current of the active short circuit according to the angle information and outputs them as d-axis current and q-axis current. Axis transformation calculation unit; It is determined whether the transient state is present through the amplitude of the d-axis current and the q-axis current, and in the case of the transient state, only the transient state component is taken from the d-axis current, and a freewheeling time for output of the freewheeling comparison value is obtained. A freewheeling duty calculation unit that calculates duty; and a freewheeling comparison value output unit that generates and outputs the freewheeling comparison value corresponding to the freewheeling time and duty. An active short circuit control device for an electric motor driving system including a.

In addition, according to one aspect of the present invention, the freewheeling duty calculation unit includes a high-pass filter block that outputs only the transient component, which is a high-frequency component, in the d-axis current using a high-pass filter; a freewheeling duty calculation block that calculates and outputs a freewheeling duty corresponding to the transient state component; And a freewheeling overvoltage protection block that selectively blocks the output of the freewheeling duty to prevent an overvoltage fault of the active short circuit. An active short circuit control device for an electric motor driving system including a.

In addition, according to one aspect of the present invention, the freewheeling overvoltage protection block compares the overvoltage fault trip voltage and the DC-link voltage for the active short circuit, and as a result of the comparison, the DC-link voltage meets the overvoltage fault trip. An active short-circuit control device for an electric motor driving system may be provided that blocks the output of the freewheeling duty when the voltage increases.

In addition, according to one aspect of the present invention, the PWM generator operates in a normal state operation mode of the motor control system, while the upper phase switch and the lower phase switch operate complementary to each other, while the PWM generator operates in a safe state of the motor control system. An active short-circuit control device for an electric motor drive system that switches to operate in active short-circuit and freewheeling mode may be provided.

In addition, according to one aspect of the present invention, the PWM generator operates as the active short circuit or freewheeling through a lower phase switch when the active short circuit operates on the low side in a transient state of the active short circuit. , or when the active short circuit operates in the high side, an active short circuit control device of the electric motor driving system that operates in the active short circuit or freewheeling may be provided through an upper phase switch.

Additionally, according to one aspect of the present invention, the drive motor system includes: an angle sensor that measures and provides an angle value of the drive motor; A current sensor that measures and provides a current value supplied to the driving motor; A power module that supplies and controls driving current to the driving motor; A DC-link capacitor provided between the high-voltage battery and the power module to minimize the effects of PWM noise and parasitic inductance; a discharge resistor that discharges the DC-link voltage stored in the DC-link capacitor within a preset time when the power connection between the high-voltage battery and the motor control system is cut off; And a voltage sensor that provides a voltage value measured at the DC-link capacitor. An active short-circuit control device for an electric motor driving system may be provided, further comprising a.

In addition, according to one aspect of the present invention, the active short circuit control device includes: the high voltage battery discharging the direct current voltage and supplying it to the DC-link capacitor; a high-side relay selectively connecting the high-voltage battery and the DC-link capacitor on the high side; And a low-side relay for selectively connecting the high-voltage battery and the DC-link capacitor at the low side. An active short-circuit control device for an electric motor driving system may be provided, further comprising a.

According to another aspect of the present invention, checking whether a safety state is requested in the driving motor system and the active short circuit current stabilizer; controlling a driving motor in a normal state operation mode in the driving motor system when the safe state is not requested; When the stable state is requested, connecting the driving motor system and the active short circuit current stabilizer to operate an active short circuit; Checking whether the active short circuit is in a transient state in an active terminal circuit current stabilizer while operating the active short circuit; When the active short circuit is in the transient state, outputting the freewheeling comparison value corresponding to current information and angle information of the driving motor from the active terminal circuit current stabilizer; and generating and outputting a PWM signal for driving control of the driving motor using a carrier wave and the freewheeling comparison value in the driving motor system. An active short-circuit control method of an electric motor driving system including a step may be provided. there is.

In addition, according to another aspect of the present invention, the step of checking whether the active short circuit is in a transient state includes converting the a-phase current, b-phase current, and c-phase current of the active short circuit according to the angle information to generate d-axis power. An active short circuit control method of an electric motor driving system that outputs current and q-axis current and determines whether the active short circuit is in the transient state through the amplitude of the d-axis current and q-axis current may be provided. .

In addition, according to another aspect of the present invention, the step of outputting the freewheeling comparison value, when in the transient state, takes only the transient state component from the d-axis current and determines the freewheeling time and duty for outputting the freewheeling comparison value. An active short-circuit control method of an electric motor driving system may be provided that calculates and generates and outputs the freewheeling comparison value corresponding to the freewheeling time and duty.

In addition, according to another aspect of the present invention, the step of generating and outputting the PWM signal includes, in a transient state of the active short circuit, when the active short circuit operates on the low side, the active short circuit is connected through the lower phase switch. Alternatively, an active short circuit control method may be provided for an electric motor driving system that operates in freewheeling or, when the active short circuit operates in the high side, through an upper phase switch.

In addition, according to another aspect of the present invention, an electric motor driving system that operates by adding a freewheeling operation according to the freewheeling comparison value generated in response to the freewheeling time and duty between active short-circuit operations of the active short circuit. An active short circuit control method may be provided.

The present invention controls the output of freewheeling between active short circuit operations for a very short period of time in order to reduce overcurrent and vibration current that occur in a transient state during active short circuit operation in an electric motor drive system, thereby reducing the size of the peak phase current. By shortening the vibration time, overcurrent and vibration current can be suppressed.

Figures 1 and 2 are diagrams illustrating two safety states of a conventional permanent magnet synchronous motor;
3 to 6 are diagrams for explaining the current response analysis of the permanent magnet synchronous motor in the active short-circuit control device of the electric motor driving system according to an embodiment of the present invention;
Figure 7 is a block diagram of an active short-circuit control device for an electric motor driving system according to an embodiment of the present invention;
8 to 18 are diagrams for explaining the detailed configuration and simulation results of the active short-circuit control device of the electric motor driving system according to an embodiment of the present invention;
Figure 19 is a flow chart showing a process for controlling an active short circuit of an electric motor drive system according to another embodiment of the present invention.

Advantages and features of the embodiments of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to be understood by those skilled in the art. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In describing embodiments of the present invention, if a detailed description of a known function or configuration is judged to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. The terms described below are terms defined in consideration of functions in the embodiments of the present invention, and may vary depending on the intention or custom of the user or operator. Therefore, the definition should be made based on the contents throughout this specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

3 to 6 are diagrams for explaining current response analysis of a permanent magnet synchronous motor in an active short-circuit control device for an electric motor driving system according to an embodiment of the present invention.

First, if the current response analysis of the permanent magnet synchronous motor is described with reference to FIGS. 3 to 6, the dq-axis voltage equation of the embedded permanent magnet synchronous motor (interior PMSM) can be expressed as Equation 1 below.

Here, v _d and v _q mean the inverter output voltage in the dq-axis synchronous coordinate system, i _d and i _q mean the motor phase current in the dq-axis synchronous coordinate system, r _s means the motor phase resistance, and L _d and L _q mean the dq-axis inductance, ω means the electric angular velocity of the motor, and ψ _m means the magnetic constant of the motor.

And, the torque equation generated by the motor can be expressed as Equation 2 below.

Here, P represents the number of poles of the motor.

When Equation 1 above is transformed into the standard form of a differential equation, it can be expressed as Equation 3 below.

Here, the inverter voltage (v _d , v _q ) supplied to the motor in the lower phase active short circuit as shown in FIG. 2 is 0, and the initial condition current is assumed to be 0 to simplify the equation. When applying the Laplace transform to Equation 3, it can be expressed as Equation 4 below.

Additionally, assuming that the speed of the motor is constant, the inverse matrix can be obtained to calculate the current response of the active short circuit, as shown in Equation 5 below.

Next, when the upper equation (i.e., inverse matrix) of Equation 5 is multiplied by both sides of Equation 4 and rearranged, Equation 6 below can be derived.

In Equation 6 above, the output current of the motor is the current response term generated by the back electromotive force voltage (ωψ _m ) of the motor, the transfer function denominator is D(s), and when the solution to D(s) is analyzed, the transfer function The extreme points of can be analyzed.

For this purpose, Equation 6 above can be defined as Equation 7 below.

And, the natural frequency can be expressed as Equation 8 below, and the damping ratio can be expressed as Equation 9 below.

Here, if the damping ratio ζ is In this case, the pole of D(s) may have the form of a complex number, and the real root component α and the virtual root component β can be expressed as Equation 10 and Equation 11 below.

Next, Figure 3 shows the change in pole according to motor speed in the active short circuit of the electric motor drive system according to an embodiment of the present invention. As the motor speed increases, the damping ratio ζ may decrease, and the d-axis inductance In the case of a motor in which the and q-axis inductances are equal, the virtual component β becomes equal to the electric angular velocity of the motor through Equation 11 above (β=ω).

And, when deriving the general solution of Equation 6 above through the inverse Laplace transform, it can be derived as Equation 12 below.

Next, when analyzing the steady-state current in the active short circuit of the electric motor driving system according to an embodiment of the present invention, in Equation 12 above, The term attached to is reduced exponentially, It can be seen that all terms tagged with are terms related to transient states.

and, If only the term without is considered, the steady-state active short-circuit dq-axis current can be calculated as Equation 13 and Equation 14 below.

Here, t _f means the time to reach the steady state, and since it decreases exponentially, mathematically the final time means infinite time (t _f =∞). thus, and can be said to be the final steady-state current value reached in the active short circuit, and from Equations 13 and 14 above, it can be seen that the steady-state dq-axis current value changes depending on the speed of the motor.

Also, when Equation 13 and Equation 14 are squared, the magnitude of the steady-state phase current occurring in an active short circuit can be calculated as Equation 15 below.

In Equation 15 above, when the speed of the motor increases infinitely, the size of the current is It converges to

In addition, looking at Equation 13 above, since the square term of the motor speed exists in both the denominator and numerator, the d-axis current continues to increase during an active short circuit as the motor speed increases, and when the motor speed is infinite, the maximum d-axis current is The magnitude of the current can be expressed as Equation 16 below.

Meanwhile, through Equation 14 above, it can be confirmed that the q-axis steady-state current changes depending on the motor speed. The biggest difference is that the d-axis current has a speed term in the denominator in the form of a square, while the q-axis current The velocity term in the denominator has the form of proportionality.

Therefore, the steady-state maximum current of the q-axis current in an active short circuit has a specific motor speed value, and when Equation 14 is differentiated according to the electric speed of the motor, it can be expressed as Equation 17 below.

Here, when calculating a solution where Equation 17 satisfies 0, it can be expressed as Equation 18 below.

In addition, Equation 18 refers to the electrical angular velocity of the motor at which the size of the q-axis current in the active short circuit is maximum. When Equation 18 is substituted into Equation 14, the maximum q-axis current size in the active short circuit is can be obtained as in Equation 19 below.

In addition, when Equation 13 and Equation 14 are substituted into Equation 3, which is the motor torque formula, the steady-state torque of the active short circuit can be expressed as Equation 20 below.

Next, considering Equation 13, Equation 14, Equation 16, and Equation 19, the trajectory of the steady-state dq-axis current according to speed can be expressed as shown in FIG. 4. When the speed is 0, the origin It starts from , and when the speed increases, the current trace appears as an elliptical trace. When the speed of the motor becomes infinite, the q-axis current becomes 0, and the d-axis current becomes In the case of a surface mounted permanent magnet synchronous motor (SPMSM) without saliency, the maximum braking torque can occur when the q-axis current is maximum.

Meanwhile, when explaining the transient current analysis of an active short circuit, Figure 5 shows the change in damping ratio and motor parameters according to motor speed. It was calculated using Equation 9 above, and the increase in motor speed Because the magnitude of current attenuation decreases, a very high overshoot current may occur in a transient state when operating an active short circuit at high motor speeds.

And, Figure 6 shows the trajectory of the dq-axis current according to speed using Equation 13 above. When the motor speed is 500, 1000, 2000, and 3000 rev/min, respectively, the active short circuit occurs with the initial motor current being 0. Shows the current waveform when carrying out.

Here, the most important point is that the oscillation of the current changes depending on the motor speed. The steady-state current is determined by Equation 13 and Equation 14, but the transient current is determined by Equation 12 above. All clauses may be included.

In addition, when driving the motor, the current limit source is controlled so that the steady-state current does not exceed, but at 2000 and 3000 rev/min, the dq axis current exceeds the motor current limit source in a transient state, which may cause additional damage to the inverter and motor. and may cause additional faults such as desaturation fault, overcurrent fault, etc. in the inverter.

As described above, when the active short circuit of the electric motor drive system operates, another safety state, freewheeling, is used to reduce overcurrent generation, but the energy stored in the permanent magnet and stator inductance is reduced by the inverter DC-link voltage. An embodiment of the present invention that uses a minimum freewheeling state to prevent overvoltage from being induced in the inverter will be described in detail below.

Figure 7 is a block diagram of an active short-circuit control device of an electric motor driving system according to an embodiment of the present invention, and Figures 8 to 18 are active short-circuit control of an electric motor driving system according to an embodiment of the present invention. This is a drawing to explain the detailed configuration of the device and simulation results.

7 to 18, the active short circuit control device of the electric motor drive system according to an embodiment of the present invention includes a drive motor 100, a drive motor system 200, an active short circuit current stabilizer 300, It may include a high voltage battery 400, etc.

The drive motor 100 may be connected to the vehicle axis to provide driving force.

The driving motor system 200 controls the driving motor 100 and operates an active short circuit depending on whether the driving motor system 200 requests a safe state, and includes an angle sensor 210, a current sensor 220, and a power It may include a module 230, a DC-link capacitor 240, a discharge resistor 250, a voltage sensor 260, a motor controller 270, etc.

Safety status requests for the drive motor system 200 as described above can be divided into internal and external. In the case of external, the safety status can be requested from a VCU (Vehicle control unit), BMS (Batter management system), etc. In other words, if normal motor control is not possible due to a serious internal or external failure, the safety state of the driving motor system 200 can be requested.

In addition, there are cases where an internal fault occurs, for example, when one or more of the 6-phase switches in the inverter outputs a fault signal, or when an error occurs in the current sensor 220, for example, in the inverter ( If the upper phase switch in phase A of the six switches (motor controller, power conversion device) breaks down in the open position, the electric motor can no longer be controlled normally. In this case, the safety state is restored through the lower phase active short circuit. can be reached

Meanwhile, the angle sensor 210 can measure and provide the angle value (i.e., angle information) of the driving motor 100, and the current sensor 220 can measure and provide the angle value (i.e., angle information) supplied to the driving motor 100. information) can be measured and provided, and the power module 230 can supply and control a driving current to the driving motor 100 by including a power semiconductor.

In addition, the DC-link capacitor 240 is provided between the high-voltage battery 400 and the power module 230 to reduce PWM (pulse-width modulation) noise used for current control and parasitic inductance (parasitic/ stay inductance), and the discharge resistor 250 connects the high-voltage battery 400 and the motor control system 200 to the high-side relay 410 and the low-side relay 420. When blocked, the DC-link voltage stored in the DC-link capacitor 240 can be passively discharged within a preset time, and the voltage sensor 260 detects the voltage value measured in the DC-link capacitor 240 (i.e. voltage information) can be provided.

Meanwhile, the motor controller 270 receives the angle value of the driving motor 100, the current value supplied to the driving motor 100, and the voltage value measured at the DC-link capacitor 240, and receives the stable state (safe). Depending on whether state) is requested, normal state output or safety state output can be selected and controlled, and may include a motor control unit 271, a transition part 272, a PWM generator 273, etc.

Here, the motor control unit 271 controls the current and torque of the drive motor 100 and can output a comparison value for driving control of the drive motor 100 in a normal state.

In addition, when the motor control system 200 is in a normal state, the switching unit 272 connects the motor control unit 271 and the PWM generator 273 and uses the comparison value output from the motor control unit 271 to the PWM generator 273. ), and when the safety state of the driving motor system 200 is requested, it operates as an active short circuit and connects the active short circuit current stabilizer 300 and the PWM generator 273 to create an active short circuit current stabilizer 300. The freewheeling comparison value output from can be transmitted.

In addition, the PWM generator 273 can generate and output a PWM signal for driving control of the drive motor 100 using the carrier wave and the comparison value or the freewheeling comparison value, which is in the normal state of the motor control system 200. In the operation mode, the upper phase switch and the lower phase switch operate complementary to each other, while in the safe state operation mode of the motor control system 200, the operation mode can be switched to active short-circuiting and freewheeling. Here, when the motor control system 200 operates with a lower phase active short circuit and freewheeling, all phase switches can be set to be off.

In addition, the PWM generator 273 operates an active short circuit when the motor control system 200 operates in a safe state, but when the active short circuit operates on the low side, the upper phase switch can always be turned off, and the PWM safety In status mode, when the lower phase switch is on, an active short circuit can operate, and when the lower phase switch is off, it can operate as freewheeling.

Meanwhile, the PWM generator 273 operates an active short circuit when the motor control system 200 operates in a safe state, but when the active short circuit operates in the high side, the lower phase switch can always be turned off, and the PWM generator 273 operates in a safe state. In safe state mode, when the upper phase switch is turned on, an active short circuit can operate, and when the upper phase switch is turned off, it can operate as freewheeling.

For example, when describing the motor controller 270, as shown in FIGS. 8 and 9, when controlling the drive motor 100 in a normal state, it can output in the form of PWM, and the PWM is a carrier wave. It can be generated using the comparison register value (Compx), and the motor control unit 271 generates the A-phase comparison value (CompA') and B-phase comparison value (CompB') corresponding to the A-phase, B-phase, and C-phase, respectively. and C-phase comparison value (CompC') can be generated by comparing them with the carrier wave, and the switching unit 272 can generate the A-phase comparison value (CompA) generated by the motor control unit 271 when the driving motor 100 is in a normal state. '), B-phase comparison value (CompB'), and C-phase comparison value (CompC') as steady-state comparison values are transmitted to the PWM generator 273, and the PWM generator 273 generates the A-phase comparison value (CompA '), B-phase comparison value (CompB'), and C-phase comparison value (CompC') and the carrier wave can be compared to output PWM.

However, when the safety state of the active short circuit is requested from the active short circuit current stabilizer 300 to the motor controller 270, the freewheeling comparison value (CompFre) generated through the active short circuit current stabilizer 300 is changed to the switching unit ( 272), it is transmitted to the PWM generator 273, and the PWM generator 273 can output PWM using this freewheeling comparison value and the carrier wave.

Meanwhile, as shown in FIG. 10, the PWM generator 273 compares the carrier wave and the comparison register value (Compx) during normal operation of the active short circuit, and when the carrier wave is relatively larger than the comparison register value (Compx), the phase switch ( ) turns on, and the lower switch ( ) operate complementary to each other and are turned off. When a change to the safe state mode is requested from the active short circuit current stabilizer 300, the PWM operation mode changes from the PWM normal state mode to the PWM safe state mode. can be converted.

Here, when operating as a low-side active short circuit (ASC), the top phase switch can be set to always turn off in the PWM safety state mode (for example, when implemented in an actual controller, the phase switch The output port can be set to change from PWM operation to GPIO), and as shown in Figure 10, the comparison register value (Compx) is the phase switch output ( ) without affecting the lower switch output ( ) only affects.

And, when the lower phase switch is turned on (on), it can operate as an active short circuit (ASC), and when the lower phase switch is turned off (off), it can operate as freewheeling.

Meanwhile, when operating as a high-side active short circuit (ASC), it can operate in the opposite way to the low-side active short circuit (ASC).

When operating as an active short circuit according to the safety state request of the driving motor system 200, the active short circuit current stabilizer 300 uses the current information and speed information of the driving motor depending on whether the active short circuit is in a transient state. A freewheeling comparison value for stabilizing the drive motor system 200 can be selected and output to the drive motor system 200, which includes an axis conversion calculation unit 310, a freewheeling duty calculation unit 320, and a freewheeling comparison value. It may include a value output unit 330, etc.

Here, the axis conversion calculation unit 310 can convert the a-phase current, b-phase current, and c-phase current of the active short circuit to the axis according to the angle information (θ) and output them as d-axis current and q-axis current.

Here, when current information (i.e., a-phase current, b-phase current, and c-phase current) and angle information (θ) are provided from the current sensor 220, the axis conversion calculation unit 310 generates a-phase current, The b-phase current and c-phase current can be converted according to the angle (θ) to calculate and output as d-axis current and q-axis current.

In addition, the freewheeling duty calculation unit 320 determines whether the active short circuit is in a transient state through the amplitude of the d-axis current and the q-axis current output from the axis conversion calculation unit 310, and determines whether the active short circuit is in a transient state. In this case, only the transient component of the d-axis current can be taken to calculate the freewheeling time and duty to output the freewheeling comparison value. The high-pass filter block 321, the freewheeling duty calculation block 322, It may include a freewheeling overvoltage protection block 323, etc.

Here, the high-pass filter block 321 determines whether the active short circuit is transient through the amplitude of the d-axis current and q-axis current output from the axis conversion calculation unit 310, and determines whether the active short circuit is transient. In this case, only the transient state component, which is a high-frequency component, can be output from the d-axis current using a high-pass filter.

In addition, the freewheeling duty calculation block 322 can calculate and output the freewheeling duty corresponding to the transient component output from the high-pass filter block 321, and calculates the size of the transient component for the d-axis current. Thus, the freewheeling time can be determined, and the freewheeling duty can be calculated and output by subtracting the size of the active short circuit current (I _ASC ) and the d-axis current.

Additionally, in Figure 12, k _d means the gain of the algorithm, means a non-linear function to serve as a limiter, and as a result, the freewheeling duty on the d-axis can be calculated, and this freewheeling duty can be output to the freewheeling overvoltage protection block 323.

Meanwhile, the freewheeling overvoltage protection block 323 can selectively block the output of the freewheeling duty to prevent overvoltage faults in the active short circuit. The overvoltage fault trip voltage for the active short circuit is compared with the DC-link voltage. , As a result of the comparison, if the DC-link voltage becomes as high as the overvoltage fault trip voltage (i.e., if the DC-link voltage has a relatively larger value than the overvoltage fault trip voltage), the output of the freewheeling duty can be blocked.

For example, as shown in FIG. 12, the freewheeling overvoltage protection block 323 uses an overvoltage fault trip voltage ( ) and the current inverter DC-link voltage ( ) can be compared, and as a result of the comparison, the overvoltage fault trip voltage ( ) than the inverter DC-link voltage ( ) is a relatively larger value (i.e., in an overvoltage state), freewheeling operation can be prohibited. .

That is, the freewheeling overvoltage protection block 323 protects against overvoltage fault trip voltage ( ) than the inverter DC-link voltage ( ) is a relatively larger value, the final freewheeling duty input from the freewheeling duty selection block 322 ( ) can block the output of overvoltage fault trip voltage ( ) than the inverter DC-link voltage ( ) is a relatively smaller value (i.e., not in an overvoltage state), determine the freewheeling duty ( ) can be printed.

The freewheeling comparison value output unit 330 can generate and output a freewheeling comparison value corresponding to the freewheeling time and duty. The freewheeling duty output from the freewheeling overvoltage protection block 323 is converted to a freewheeling comparison value. After being generated, it can be output to the switching unit 272 provided in the motor controller 270 of the motor drive controller 200 and transmitted to the PWM generation unit 273.

The high-voltage battery 400 can discharge direct current voltage and supply it to the DC-link capacitor 240, and a high-side relay 410 selectively connects the high-side between the high-voltage battery 400 and the DC-link capacitor 240. ) may be provided, and a low-side relay 420 may be provided to selectively connect the high-voltage battery 400 and the DC-link capacitor 240 on the low side.

Meanwhile, when explaining the simulation results of the active short-circuit control device of the electric motor drive system as described above with reference to FIGS. 13 to 18, the parameters of the motor used in the simulation are as shown in the table of FIG. 5, The margin current (I _m ) is set to 1A, and this margin current can serve to operate only when the freewheeling time injection is transient.

Here, a small margin current allows the freewheeling state to operate even in a normal state, which can cause high voltage in the inverter, and a large margin current can cause the algorithm proposed in one embodiment of the present invention (i.e., active short-circuit control technique). It limits the range of motion and reduces motion performance.

Meanwhile, all simulations were performed with the motor speed fixed at 1200 rev/min, and the boundary current value (I _ASC ) that determines freewheeling was selected considering Equation 15 and the margin current, and the gain value (k The selection of _d ) is close to the maximum allowable current value, and the field current ( ) is about 40A, and the current limit (I _max ) is 45A.

Additionally, in order to operate the phase current within 45A, It was calculated using , and the gain (k _d ) can be calculated as 0.2.

Meanwhile, Figure 13 shows the a-phase, b-phase, and c-phase currents of the motor and the dq-axis current when the active short circuit operates when the algorithm proposed in an embodiment of the present invention is not applied. In this case, the output voltage from the inverter becomes 0, and current can be generated as shown in Equation 12 above. Due to the low damping ratio (ζ), it can be confirmed that the b-phase current of the motor overshoots and oscillates up to 49A in the transient state. .

And, Figure 14 shows the a-phase, b-phase, c-phase currents and dq-axis current of the motor when the active short circuit operates when the algorithm proposed in an embodiment of the present invention is applied, and the maximum current of the b-phase current is 39.8. A, and when compared with Figure 13, it can be seen that the peak current has decreased by about 9.2A.

In addition, when analyzing the effectiveness of the algorithm performance proposed in an embodiment of the present invention through the trajectory of the dq-axis current as shown in FIG. 15, if the proposed algorithm is not applied, the dq-axis current in the transient state is the current limiting source. It goes out, but when the proposed algorithm is applied, the dq-axis current comes into the current limiting source.

Meanwhile, the following experiment was performed to verify the algorithm proposed in an embodiment of the present invention. The microphone controller was TMS28377D, the switching frequency was selected at 5 kHz, and the algorithm gain (k _d ) was the same as in the simulation. is 0.2, the margin current (I _m ) is set to 1A, the speed is controlled at 1200 rev/min in the dynamo motor, the sample motor that performed the algorithm is operated in torque control mode, and the sample motor is self-driving. It was controlled by a manufactured three-phase inverter, and PM100RL1A060 was used as the power module.

And, Figure 10 shows a technique for outputting PWM by mixing the actual low-side active short circuit (Low-side ASC) and freewheeling mode. During normal operation, the carrier wave is compared with CompA, which is the carrier wave comparison register value. If it is greater than CompA, the upper phase switch ( ) turns on, and the lower switch ( ) operate complementary to each other and turn off.

Next, when a request is made to switch to the safe state mode, the PWM operation mode is switched from normal to safe state mode. When operating with a low-side active short circuit (Low-side ASC), the upper phase switch is set to always turn off in the safe state ( For example, when implemented in an actual microcontroller, the phase switch output port can be set to change from PWM operation to GPIO), and as shown in Figure 10, CompA does not affect the upper phase switch output and only lower phase PWM. It only affects the , and when the lower phase is turned on, it can operate as ASC, and when the lower phase is turned off, it can operate as freewheeling.

Therefore, in the existing inverter system, the active short circuit (ASC) and freewheeling time can be freely controlled by only changing the settings of the microcontroller.

Meanwhile, Figures 16 to 18 show waveforms of algorithm experiment results proposed in an embodiment of the present invention. The motor is operating at 1200 rev/min, and when operating an active short circuit, the a-phase, b-phase, c-phase, and dq axis Indicates motor current.

Here, Figure 16 shows a case where the active short circuit (ASC) is operated without applying the algorithm proposed in an embodiment of the present invention. Similar to the simulation result as shown in Figure 13, the active short circuit (ASC) ASC) operates, a large current is generated in a transient state, and it can be confirmed that a large current is generated in the b phase up to approximately 52 A.

In addition, in the q-axis current where the torque component is generated, the minimum q-axis current during active short circuit (ASC) operation is ??33 A, and it can be seen that the magnitude of the vibration current thereafter fluctuates at an amplitude of about 23 A.

Meanwhile, Figure 17 shows a case of operation of an active short circuit (ASC) with the algorithm proposed in an embodiment of the present invention applied, and the current waveform of the present invention is compared to the current waveform shown in Figure 16. In one embodiment, by using the proposed algorithm, the freewheeling duty falls within the active short circuit (ASC) operation, and as a result, it can be confirmed that the magnitudes of the a-phase, b-phase, and c-phase currents are all limited to within about 40A. .

In addition, it can be seen that the amplitude of the q-axis current oscillation has decreased compared to the amplitude shown in FIG. 16, and compared to the simulation results shown in FIG. 14, it can be seen that the phase current and dq current show very similar results. However, there is a slight difference in the freewheeling duty value, which is due to differences in the motor model caused by nonlinearity of the motor and parasitic inductance (stray inductance) that exists inside the inverter.

And, Figure 18 shows the experimental results of the trajectory of dq current depending on whether or not the algorithm proposed in an embodiment of the present invention is used. Figure 18 (a) shows the results of an experiment in which an active short circuit (ASC) is operated using the existing method. In this case, it can be confirmed that the dq current is outside the current limiting source, while when using the algorithm proposed in an embodiment of the present invention, the trajectory of the dq-axis current is as shown in (b) of FIG. 18. You can confirm that it comes within the current limiting source.

As described above, the active short circuit control device of the electric motor driving system according to an embodiment of the present invention uses freewheeling, which is one of the safety states of the motor, but determines the freewheeling injection time and sets the freewheeling duty to the active short circuit. By injecting the transient state during circuit operation, not only can the overcurrent be reduced, but also the vibration time can be reduced. As a result, the motor current can be controlled to operate within the current limit source by reducing the maximum motor phase current. By using only the phase current in the process of determining the freewheeling duty, the safe state of the active short circuit can be implemented without the motor angle or other additional sensing information, which can increase the robustness of the algorithm against sensor faults. there is.

Therefore, in one embodiment of the present invention, in order to reduce overcurrent and vibration current that occur in a transient state during active short-circuit operation in an electric motor drive system, freewheeling is controlled for a very short period of time between active short-circuit operations, thereby reducing the peak By reducing the size of the phase current and shortening the vibration time, overcurrent and vibration current can be suppressed.

Figure 19 is a flow chart showing a process for controlling an active short circuit of an electric motor drive system according to another embodiment of the present invention.

Referring to FIG. 19, the driving motor system 200 and the active short circuit current stabilizer 300 check whether the safety state of the driving motor system 200 is requested (step 1910).

Here, the safety status request of the driving motor system 200 can be divided into internal and external. In the case of external, the safety status can be requested from a VCU (Vehicle control unit), BMS (Batter management system), etc. In other words, if normal motor control is not possible due to a serious internal or external failure, the safety state of the driving motor system 200 can be requested.

In addition, there are cases where an internal fault occurs, for example, when one or more of the 6-phase switches in the inverter outputs a fault signal, or when an error occurs in the current sensor 220, for example, in the inverter ( If the upper phase switch in phase A of the six switches (motor controller, power conversion device) breaks down in the open position, the electric motor can no longer be controlled normally. In this case, the safety state is restored through the lower phase active short circuit. can be reached

As a result of the check in step 1910, if the safety state of the drive motor system 200 is not requested, the drive motor system 200 can control the drive motor 100 in a normal operation mode (step 1920). )

For example, the motor control unit 271 of the motor controller 270 can output a comparison value for driving control of the drive motor 100 in a normal state, and the switching unit 272 can output a comparison value for driving control of the drive motor 100 in a normal state, and the motor control unit 271 and the PWM The generation unit 273 is connected to transmit the comparison value output from the motor control unit 271 to the PWM generation unit 273, and the PWM generation unit 273 uses the carrier wave and the comparison value to drive the drive motor 100. A PWM signal for control can be generated and output.

Here, in the normal operation mode of the motor control system 200, the upper phase switch and the lower phase switch may operate complementary to each other.

Meanwhile, as a result of the check in step 1910, if the safe state of the drive motor system 200 is requested, the drive motor system 200 generates an active terminal circuit current through the switching unit 272 of the drive motor controller 270. By connecting the stabilizer 300 and the PWM generator 273, the active short circuit can be operated (step 1930).

Additionally, while operating the active short circuit in the drive motor system 200, it is possible to check whether the active short circuit is in a transient state in the active terminal circuit current stabilizer 300 (step 1940).

In the step 1940 of checking whether the active short circuit is in a transient state, the a-phase current, b-phase current, and c-phase current of the active short circuit are converted into axis according to angle information and output as d-axis current and q-axis current, It is possible to determine whether the active short circuit is in a transient state through the amplitude of the d-axis current and q-axis current.

For example, in the axis conversion calculation unit 310, when current information (i.e., a-phase current, b-phase current, and c-phase current) from the current sensor 220 and angle information (θ) are provided from the angle sensor 210, the a-phase current , b-phase current and c-phase current can be converted according to the angle (θ) to calculate and output as d-axis current and q-axis current.

In addition, the freewheeling duty calculation unit 320 can determine whether the active short circuit is in a transient state through the amplitude of the d-axis current and q-axis current output from the axis conversion calculation unit 310, and the high-pass filter Block 321 determines whether the active short circuit is in a transient state through the amplitude of the d-axis current and q-axis current output from the axis conversion calculation unit 310, and if the active short circuit is in a transient state, the d-axis current By using a high-pass filter, only the transient component, which is a high-frequency component, can be output.

Next, as a result of the check in step 1940, if the active short circuit is in a transient state, the active terminal circuit current stabilizer 300 can output a freewheeling comparison value (step 1950).

In the step (1950) of outputting the freewheeling comparison value, when the active short circuit is in a transient state, only the transient state component is taken from the d-axis current to calculate the freewheeling time and duty for output of the freewheeling comparison value, and calculate the freewheeling time and duty for output of the freewheeling comparison value. Freewheeling comparison values corresponding to time and duty can be generated and output.

For example, the freewheeling duty calculation block 322 can calculate and output the freewheeling duty corresponding to the transient component output from the high-pass filter block 321, and the size of the transient component for the d-axis current. The freewheeling time can be determined by calculating, and the freewheeling duty can be calculated and output by subtracting the size of the active short circuit current (I _ASC ) and the d-axis current.

In addition, the freewheeling overvoltage protection block 323 can block the output of the final freewheeling duty input from the freewheeling duty selection block 322 when the inverter DC-link voltage is relatively larger than the overvoltage fault trip voltage. If the inverter DC-link voltage is relatively smaller than the overvoltage fault trip voltage (i.e., not in an overvoltage state), the freewheeling duty can be determined and output.

Next, the driving motor system 200 can generate and output a PWM signal for driving control of the driving motor using the carrier wave and the freewheeling comparison value (step 1960).

In the step (1960) of generating and outputting the PWM signal, in the transient state of the active short circuit, when the active short circuit operates on the low side, it operates as an active short circuit or freewheeling through the lower phase switch, or When the circuit operates on the high side, it can operate as an active short circuit or freewheeling through the upper phase switch.

For example, the PWM generator 273 compares the carrier wave and the comparison register value during normal operation of the active short circuit, and when the carrier wave is relatively larger than the comparison register value, the phase switch is turned on, and the lower phase switch is They operate complementary to each other and are turned off. When a switch to the safe state mode is requested from the active short circuit current stabilizer 300, the PWM operation mode can be switched from the PWM normal state mode to the PWM safe state mode.

Here, when operating as a low-side active short circuit (ASC), the top phase switch can be set to always turn off in the PWM safety state mode (for example, when implemented in an actual controller, the phase switch The output port can be set to change from PWM operation to GPIO), and the comparison register value does not affect the phase switch output, but only the lower phase switch output.

And, when the lower phase switch is turned on (on), it can operate as an active short circuit (ASC), and when the lower phase switch is turned off (off), it can operate as freewheeling.

Meanwhile, when operating as a high-side active short circuit (ASC), it can operate in the opposite way to the low-side active short circuit (ASC).

That is, in the safety state mode of the motor control system 200 as described above, a freewheeling operation corresponding to the freewheeling comparison value can be added between the active short circuit operations of the active short circuit, and this freewheeling is performed in the inverter. It can be added in a very short time as it can cause overvoltage.

Therefore, in another embodiment of the present invention, in order to reduce overcurrent and vibration current that occur in a transient state during active short-circuit operation in an electric motor drive system, freewheeling is controlled for a very short period of time between active short-circuit operations, thereby reducing the peak By reducing the size of the phase current and shortening the vibration time, overcurrent and vibration current can be suppressed.

In the above description, various embodiments of the present invention have been presented and explained, but the present invention is not necessarily limited thereto, and those skilled in the art will understand various embodiments without departing from the technical spirit of the present invention. It will be easy to see that branch substitutions, transformations, and changes are possible.

100: driving motor
200: Drive motor system
210: Angle sensor
220: current sensor
230: Power module
240: DC-link capacitor
250: Discharge resistance
260: Voltage sensor
270: motor controller
271: Motor control unit
272: switching unit
273: PWM generation unit
300: Active short circuit current stabilizer
310: Axis transformation calculation unit
320: Freewheeling duty calculation unit
321: High-pass filter block
322: Freewheeling duty calculation block
323: Freewheeling overvoltage protection block
330: Freewheeling comparison value output unit
400: High voltage battery
410: High side relay
420: Low side relay

Claims (14)

A drive motor connected to the vehicle axle to provide driving force;
a drive motor system that controls the drive motor and operates an active short circuit depending on whether a safety state of the drive motor system is requested; and
When the active short circuit is operated, a freewheeling comparison value for stabilizing the drive motor system is selected and generated using the current information and angle information of the drive motor depending on whether the active short circuit is in a transient state. Active short-circuit current stabilizer outputting to the motor system;
An active short-circuit control device for an electric motor drive system including a.
In claim 1,
The driving motor system includes a motor controller that selects and controls a steady state output or a safe state output depending on whether a stable state is requested,
The motor controller is,
a motor control unit that controls the current and torque of the driving motor and outputs a comparison value for driving control of the driving motor in a normal state;
In the normal state, the comparison value output from the motor control unit is transmitted, and when the safety state of the driving motor system is requested, it operates as an active short circuit and receives the freewheeling comparison value output from the active short circuit current stabilizer. a switching unit that transmits; and
a PWM generator that generates and outputs a PWM signal for driving control of the drive motor using a carrier wave and the comparison value or freewheeling comparison value;
An active short-circuit control device for an electric motor drive system including a.
In claim 2,
The active short circuit current stabilizer is,
An axis conversion calculation unit that converts the a-phase current, b-phase current, and c-phase current of the active short circuit according to the angle information and outputs them as d-axis current and q-axis current;
It is determined whether the transient state is present through the amplitude of the d-axis current and the q-axis current, and in the case of the transient state, only the transient state component is taken from the d-axis current, and a freewheeling time for output of the freewheeling comparison value is obtained. A freewheeling duty calculation unit that calculates duty; and
a freewheeling comparison value output unit that generates and outputs the freewheeling comparison value corresponding to the freewheeling time and duty;
An active short-circuit control device for an electric motor drive system including a.
In claim 3,
The freewheeling duty calculation unit,
a high-pass filter block that outputs only the transient component, which is a high-frequency component, from the d-axis current using a high-pass filter;
a freewheeling duty calculation block that calculates and outputs a freewheeling duty corresponding to the transient state component; and
a freewheeling overvoltage protection block that selectively blocks the output of the freewheeling duty to prevent an overvoltage fault of the active short circuit;
An active short-circuit control device for an electric motor drive system including a.
In claim 4,
The freewheeling overvoltage protection block is,
Compares the overvoltage fault trip voltage and DC-link voltage for the active short circuit, and as a result of the comparison, blocks the output of the freewheeling duty when the DC-link voltage becomes as high as the overvoltage fault trip voltage.
Active short-circuit control device for electric motor drive system.
In claim 5,
The PWM generator,
In the normal state operation mode of the motor control system, the upper phase switch and the lower phase switch operate complementary to each other, while in the safe state operation mode of the motor control system, they are switched to operate in active short-circuiting and freewheeling.
Active short-circuit control device for electric motor drive system.
In claim 6,
The PWM generator,
In the transient state of the active short circuit,
When the active short circuit operates on the low side, it operates as the active short circuit or freewheeling through the lower phase switch, or
When the active short circuit operates in the high side, the active short circuit or freewheeling operates through the upper phase switch.
Active short-circuit control device for electric motor drive system.
The method according to any one of claims 1 to 7,
The driving motor system is,
An angle sensor that measures and provides an angle value of the drive motor;
A current sensor that measures and provides a current value supplied to the driving motor;
A power module that supplies and controls driving current to the driving motor;
A DC-link capacitor provided between the high-voltage battery and the power module to minimize the effects of PWM noise and parasitic inductance;
a discharge resistor that discharges the DC-link voltage stored in the DC-link capacitor within a preset time when the power connection between the high-voltage battery and the motor control system is cut off; and
A voltage sensor providing a voltage value measured at the DC-link capacitor;
An active short-circuit control device for an electric motor drive system further comprising a.
In claim 8,
The active short circuit control device,
The high voltage battery discharging the direct current voltage and supplying it to the DC-link capacitor;
a high-side relay selectively connecting the high-voltage battery and the DC-link capacitor on the high side; and
a low-side relay selectively connecting the high-voltage battery and the DC-link capacitor on the low side;
An active short-circuit control device for an electric motor drive system further comprising a.
Checking whether a safe state is requested in the drive motor system and the active short-circuit current stabilizer;
controlling a driving motor in a normal state operation mode in the driving motor system when the safe state is not requested;
When the stable state is requested, connecting the driving motor system and the active short circuit current stabilizer to operate an active short circuit;
Checking whether the active short circuit is in a transient state in an active terminal circuit current stabilizer while operating the active short circuit;
When the active short circuit is in the transient state, outputting the freewheeling comparison value corresponding to current information and angle information of the driving motor from the active terminal circuit current stabilizer; and
generating and outputting a PWM signal for driving control of the driving motor in the driving motor system using a carrier wave and the freewheeling comparison value;
Active short circuit control method of an electric motor drive system including.
In claim 10,
The step of checking whether the active short circuit is in a transient state is:
The a-phase current, b-phase current, and c-phase current of the active short circuit are converted according to the angle information and output as d-axis current and q-axis current, and the active short circuit is generated through the amplitudes of the d-axis current and q-axis current. To determine whether the above transient state is
Active short circuit control method of electric motor drive system.
The method of claim 11,
The step of outputting the freewheeling comparison value is,
In the case of the transient state, only the transient state component is taken from the d-axis current to calculate the freewheeling time and duty for output of the freewheeling comparison value, and to generate the freewheeling comparison value corresponding to the freewheeling time and duty. printing
Active short circuit control method of electric motor drive system.
The method of claim 12,
The step of generating and outputting the PWM signal is,
In the transient state of the active short circuit,
When the active short circuit operates on the low side, it operates as the active short circuit or freewheeling through the lower phase switch, or
When the active short circuit operates in the high side, the active short circuit or freewheeling operates through the upper phase switch.
Active short circuit control method of electric motor drive system.
The method of claim 13,
The step of generating and outputting the PWM signal is,
Operating by adding a freewheeling operation according to the freewheeling comparison value generated in response to the freewheeling time and duty between the active short circuit operations of the active short circuit.
Active short circuit control method of electric motor drive system.