WO2022058005A1 - Method for compensating for the effects of a dead time when driving analogue switches of a power converter and arrangement for supplying a load - Google Patents

Method for compensating for the effects of a dead time when driving analogue switches of a power converter and arrangement for supplying a load Download PDF

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Publication number
WO2022058005A1
WO2022058005A1 PCT/EP2020/075859 EP2020075859W WO2022058005A1 WO 2022058005 A1 WO2022058005 A1 WO 2022058005A1 EP 2020075859 W EP2020075859 W EP 2020075859W WO 2022058005 A1 WO2022058005 A1 WO 2022058005A1
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WO
WIPO (PCT)
Prior art keywords
alternating current
duty cycle
compensation
current
driver
Prior art date
Application number
PCT/EP2020/075859
Other languages
French (fr)
Inventor
Michael Dubreuil
Jeremy LETOT
Benoit Robin
Original Assignee
HELLA GmbH & Co. KGaA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by HELLA GmbH & Co. KGaA filed Critical HELLA GmbH & Co. KGaA
Priority to CN202080107195.3A priority Critical patent/CN116458046A/en
Priority to PCT/EP2020/075859 priority patent/WO2022058005A1/en
Priority to EP20772300.8A priority patent/EP4214829A1/en
Publication of WO2022058005A1 publication Critical patent/WO2022058005A1/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0025—Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/38—Means for preventing simultaneous conduction of switches
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/38—Means for preventing simultaneous conduction of switches
    • H02M1/385—Means for preventing simultaneous conduction of switches with means for correcting output voltage deviations introduced by the dead time
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • H02M7/53876—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/046—Controlling the motor

Definitions

  • the invention is related a method for compensating for the effects of a dead time when driving analogue switches of a power converter and to an arrangement for supplying a load, for example an alternating current motor from a direct current source with sinusoidal three-phase alternating current.
  • Such an arrangement may comprise
  • power converter for example an inverter, a DC-AC-converter or a DC-DC converter comprising at least one half bridge of analogue switches,
  • the at least one half-bridge is arranged between the terminals of the direct current input and wherein a node located between the analogue switches of the half-bridge is connected to the at least one terminal for an outer conductor of the alternating current output,
  • the driver drives the analogue switches in that way that the current is commutated from one analogue switch to the other analogue switch of the at least one half-bridge, wherein neither one nor the other analogue switch of the half-bridge is conductive for a dead time during commutation to prevent a short circuit between the terminals of the direct current input, and wherein during the dead time a current occurs via a diode, which is part of each of the analogue switches or which is arranged parallel to each of the analogue switches to be switched on, which leads to a deviation of the current flowing via the at least one terminal of the alternating current output from the reference current or
  • the driver comprises at least one means for compensating for the deviation of the currents via the alternating current output from the reference current or the voltage at the alternating current output from the reference voltage, with which the duty cycle calculated by the means for calculating the duty cycle can be changed for the purpose of compensation.
  • the driver is connected to an output of the control unit and has a control signal output to which the control signal terminals of a controlled six-pulse bridge circuit of the inverter are connected.
  • a DC input of the inverter is connected via an on-board power supply to a battery that supplies the current that is converted by the inverter into an AC current and made available at the AC output of the inverter.
  • the motor is connected to the AC output.
  • the motor is connected to the steering rod of a motor vehicle via a transmission, which is coupled to the steered wheels and connected to a steering wheel.
  • a torque sensor is attached to the steering rod which measures a torque applied to the steering rod by a driver via the steering wheel.
  • An output of the torque sensor is connected to the control unit so that an electrical signal generated by the torque sensor is supplied to the control unit.
  • a position sensor is provided on the engine to detect the position of the engine rotor.
  • the position sensor is also connected to the ECU.
  • the motor is to be used to generate a desired torque, which is detected by the torque sensor.
  • the sensor data is used to determine values for reference currents that are to flow through the motor windings in order to achieve the desired torque.
  • the values for the reference currents are transferred from the control unit to the driver, which generates PWM control signals from the values for the reference currents, with which the MOSFETs of the inverter are controlled.
  • the control can be a vector control.
  • the reference currents can be transformed into the D/Q plane.
  • the values for the currents transformed into the D/Q plane can then be transferred from the controller to the driver, which determines the duty cycles of the PWM control signals from the currents transformed into the D/Q plane in order to generate a voltage that drives the desired currents through the motor.
  • commutation also occurs in which the current is transferred from one MOSFET of a half-bridge of the bridge circuit to another MOSFET of the half-bridge.
  • a dead time is set up between the opening of the MOSFET delivering the current and the closing of the MOSFET receiving the current. This dead time has an impact on the motor current and the torque generated by the motor.
  • a freewheeling current is driven through windings in the motor via the body diode of the receiving MOSFET.
  • This freewheeling current causes the voltage applied to the motor to drop or rise, which causes the motor current to deviate from the sinusoidal form, particularly at low currents or with small duty cycles, and consequently leads to torque oscillations that can be felt as vibrations and can be perceived as disturbing.
  • Dead time impact occurring in switching circuitries with analogues switches may affect also the power supply with other arrangements. So problem is to avoid or at least minimize such a dead time impact.
  • the problem is overcome by determining the compensation value by the means for compensation based on an extrapolated physical quantity that occurs at the load.
  • the extrapolated physical quantity may be extrapolated by a means for extrapolating designed to extrapolate the physical quantity that occurs at the load.
  • the driver comprises at least one means for extrapolating de-signed to extrapolate the physical quantity that occurs at the load, whereby by the means for extrapolating the future currents flowing via the alternating current output or the voltage at the future currents can be calculated by the extrapolation of the physical quantity.
  • the invention is now based on the problem of proposing a further method with which it is easier and faster to achieve compensation for dead time.
  • the problem which is too basic for the invention, is solved by supplementing the method mentioned above by in that the driver comprises at least one means for extrapolating de-signed to extrapolate the physical quantity that occurs at the load and whereby by the means for extrapolating the future currents flowing via the alternating current output or the voltage at the future currents can be calculated by the extrapolation of the physical quantity.
  • the means for compensation may have a first input. This first input may be connected to the output of the electronic control unit at which the signal indicating the reference current or the reference voltage is provided.
  • An arrangement according to the invention may comprise a sensor for measuring the physical quantity which is connected to the one input for the sensed physical quantity.
  • the load may be a motor and the sensed physical quantity is the rotor position of the motor.
  • the motor may be the motor of an EPS-System.
  • the arrangement may include a sensor for measuring the rotor position of the motor having an output for a sensor signal connected to an input for the rotor position indicating sensor signal of the means for extrapolating. The sensor signal indicating the rotor position can be read into the means for extrapolating via this input.
  • the arrangement may also include a sensor for measuring the rotor speed of the motor having a sensor signal output connected to a rotor speed sensor signal input of the means for extrapolating.
  • the rotor speed sensor signal can be read into the means for extrapolating via this input.
  • the extrapolated rotor position expressed by an angle 0 extrapolated as a function of the measured angle 0 meaS ured and the rotor speed co, can be determined by the following equation
  • future currents flowing through the AC output can be calculated from the reference current and the future rotor position, especially by extrapolation. It is possible that the future current is calculated for at least one point in time that lies, for example, 50ps, 100ps, 150ps or 200ps in the future.
  • the extrapolated target current I ex trapoiated can be calculated as follows:
  • an assigned compensation value can be determined from the future currents flowing through the terminal of the AC output for each duty cycle determined by the means for calculating duty cycles. These compensation value, each associated with a determined duty cycle, can then be added to the associated duty cycle by the means for compensation, thereby calculating compensated a duty cycle and generating compensated PWM control signal which can be provided at a terminal of the output of the driver.
  • the means for calculating the duty cycles can be used to calculate the duty cycle from the target current according to a functional equation of a first function.
  • the compensation values assigned to this duty cycle can be calculated according to the functional equation of the inverse function of the first function as a function of the future current.
  • the compensation value can be determined by a calculation according to a sigmoid function or a sigmoid series as a function of the future current.
  • the means for compensation determines the compensation value as a function of the future currents by reading out a look-up table which can be stored in the means for compensation.
  • the analogue switches can be MOSFETs, IGBTs or other suitable switches.
  • the power converter may be an inverter, a AC-DC-converter or a DC-DC-converter.
  • the power converter may be a buck converter or a boost converter of a topology comprising at least one half bridge of analogue switches.
  • the power converter may comprise half bridges in any topology, for example in a H-bridge or a six-pulse bridge.
  • the power converter may be suitable for any number of phases.
  • the load may be a DC-Motor, a BLDC-motor, a BLAC motor, a further converter, or any suitable DC or AC load.
  • the method according to the invention can be used to compensate for the effects of dead time when driving analogue switches of an inverter, a DC-AC-converter or a DC- DC converter with a controlled six-pulse bridge circuit.
  • compensation values are determined for duty cycles which were calculated by a means for calculating duty cycles.
  • the compensation values are added to the calculated duty cycles to compensate for the effects of dead times to obtain compensated duty cycles. These compensated duty cycles are then used to drive the inverter, the DC-AC-converter or the DC-DC converter analogue switches.
  • Fig. 1 shows a simplified equivalent circuit diagram of the power section of a three- phase inverter of an arrangement according to the invention and of a motor which is supplied by the arrangement according to the invention with a preferably sinusoidal alternating current,
  • Fig. 2 a block diagram of an electronic control unit and a driver of the arrangement according to the invention
  • Fig. 4 a graphic representation of the dependence of the current on the duty cycle in the ideal case and taking into account the dead time
  • Fig. 5 a time curve of motor currents without and with compensation of the dead time
  • the arrangement according to the invention comprises a three-phase inverter I, a control unit ECU and a driver D.
  • the arrangement has an input for connection to a DC onboard power supply Ubat and an output for connection to an AC motor M.
  • the three- phase inverter is designed to convert the DC voltage of the on-board power supply into a three-phase AC voltage for supplying the motor M.
  • the three-phase inverter has a controlled six-pulse bridge circuit with three half bridges of MOSFETs.
  • a DC input of the three-phase inverter forms the input of the device for connection to the DC on-board power system.
  • An AC output U, V, W of the inverter I forms the output of the arrangement for connection to the motor M.
  • the half-bridges of the controlled six-pulse bridge circuit are arranged between terminals of the DC input and nodes located between the MOSFETs of a half-bridge are connected to one of the three terminals of the AC output.
  • the MOSFETs of the halfbridges have a control signal input which is not shown in the figures. These control signal inputs are connected to driver D. These connections are also not shown in the figures.
  • the driver generates control signals to drive the MOSFETs. In driver D, a PWM signal is generated for each MOSFET as a control signal.
  • the driver D has an input connected to the electronic control unit ECU.
  • the electronic control unit ECU generates control variables Vd, Vq for each phase, which correspond to d/q-transformed reference voltages at the terminals U, V, W of the AC output of the arrangement. From these control variables Vd, Vq, a means for calculating, by space vector modulation of duty cycles, the duty cycles of the PWM signals driving the inverter MOSFETs of each half bridge of the six-pulse bridge are determined.
  • dead times are required for commutation of currents between the MOSFETs of a half-bridge to prevent shot-throughs.
  • control signals generated of each half bridge of the six-pulse bridge by the means for calculating the duty cycles are routed to the control signal inputs of the MOSFETs in order to control them. This results in the deviations between the ideal current curve and the real current curve described at the beginning and shown in Fig. 4 for the range of the zero crossing of the alternating current. This is also shown in the left half of Figure 5. This deviation of the alternating current from the sinusoidal form leads to torque fluctuations which could be perceived as disturbing by a driver.
  • the duty cycles determined by the means for calculating the duty cycles are therefore changed by taking compensation values into account.
  • This change in the duty cycles compensates for the effects of dead times.
  • This change is made by a means of compensation which also determines the compensation values with which the duty cycles of each MOSFET are determined.
  • the means for compensation provides compensated duty cycles a pplied for each MOSFET of each half bridge of the six-pulse bridge.
  • the inventive arrangement has a sensor for measuring the rotor position 0 meaS ured of the motor and a sensor for measuring the rotor speed to. From these sensors, a sensor signal indicating the rotor position 0 meaS ured and a sensor signal indicating the rotor speed a) are supplied to a means for extrapolating of the driver D.
  • a future rotor position 0 extrapolated at a point in time that is one time later than the measurement time by a period of time At is extrapolated from the sensor signals. For this purpose, the following is calculated:
  • extrapolated reference current I ex trapoiated are calculated in a second step as follows
  • a compensation value is then determined in a next step for each calculated duty cycle, for example by looking in a lookup table or by calculation using a function, for example a sigmoid function. Environment parameters env_param could be taken in to account, when the compensation value is determined.
  • compensated duty cycle is then obtained, from which a PWM signal is then determined for the MOSFET of the controlled six-pulse bridge circuit of the three-phase inverter, with which the MOSFETs is driven.

Abstract

The invention relates to an arrangement for supplying a load, for example an alternating current motor (M), from a direct current source (Ubat) with alternating current • with one direct current input, with two terminals, • with one alternating current output (U, V, W) with at least one terminal for an outer conductor, • with at least one input for a sensed physical quantity that occurs at the load, • with an inverter (I) comprising at least one half bridge of analogue switches, • with an electronic control unit (ECU) for controlling the alternating current, whereby signals for at least one reference current or reference voltage, which is to be set at the alternating current output of the inverter (I), can be provided at one output by the control unit (ECU), and • with a driver (D) which is connected to the control unit (ECU) and with which at least one PWM control signal for switching the analogue switches on and off can be generated from the at least one reference current or reference voltage, the driver having means for calculating the at least one duty cycle of the PWM control signal, • whereby the driver drives the analogue switches in that way that the current is commutated from one analogue switch to the other analogue switch of the half-bridge, wherein neither one nor the other analogue switch of the half-bridge is conductive for a dead time during commutation, • whereby the driver comprises at least one means for compensating for a deviation of the currents via the alternating current output from the reference current or the voltage at the alternating current output from the reference voltage, with which the duty cycle calculated by the means for calculating the duty cycle can be changed for the purpose of compensation.

Description

Method for compensating for the effects of a dead time when driving analogue switches of a power converter and Arrangement for supplying a load
Description
The invention is related a method for compensating for the effects of a dead time when driving analogue switches of a power converter and to an arrangement for supplying a load, for example an alternating current motor from a direct current source with sinusoidal three-phase alternating current.
Such an arrangement may comprise
• one direct current input, with two terminals,
• one alternating current output with at least one terminal for an outer conductor,
• at least one input for a sensed physical quantity that occurs at the load,
• power converter, for example an inverter, a DC-AC-converter or a DC-DC converter comprising at least one half bridge of analogue switches,
• wherein the at least one half-bridge is arranged between the terminals of the direct current input and wherein a node located between the analogue switches of the half-bridge is connected to the at least one terminal for an outer conductor of the alternating current output,
• with an electronic control unit for controlling the alternating current,
• whereby signals for at least one reference current or reference voltage, which is to be set at the alternating current output of the converter, can be provided at one output by the control unit, and
• with a driver which is connected to the control unit and with which at least one PWM control signal for switching the analogue switches on and off can be generated from the at least one reference current or reference voltages, the driver having an output with terminals which are connected to control signal terminals of the analogue switches, and the driver having means for calculating the at least one duty cycle of the PWM control signal, • whereby the driver drives the analogue switches in that way that the current is commutated from one analogue switch to the other analogue switch of the at least one half-bridge, wherein neither one nor the other analogue switch of the half-bridge is conductive for a dead time during commutation to prevent a short circuit between the terminals of the direct current input, and wherein during the dead time a current occurs via a diode, which is part of each of the analogue switches or which is arranged parallel to each of the analogue switches to be switched on, which leads to a deviation of the current flowing via the at least one terminal of the alternating current output from the reference current or which leads to a deviation of the voltage at the alternating current output,
• whereby the driver comprises at least one means for compensating for the deviation of the currents via the alternating current output from the reference current or the voltage at the alternating current output from the reference voltage, with which the duty cycle calculated by the means for calculating the duty cycle can be changed for the purpose of compensation.
Such arrangements are used, for example, to control a servomotor of an Electric Power Steering (EPS) system, with which the steering angle at the wheels of a motor vehicle can be adjusted. Document US 10494 016 B2 discloses an electric power steering apparatus.
These arrangements have an electronic control unit. The driver is connected to an output of the control unit and has a control signal output to which the control signal terminals of a controlled six-pulse bridge circuit of the inverter are connected. A DC input of the inverter is connected via an on-board power supply to a battery that supplies the current that is converted by the inverter into an AC current and made available at the AC output of the inverter. The motor is connected to the AC output. The motor is connected to the steering rod of a motor vehicle via a transmission, which is coupled to the steered wheels and connected to a steering wheel. A torque sensor is attached to the steering rod which measures a torque applied to the steering rod by a driver via the steering wheel. An output of the torque sensor is connected to the control unit so that an electrical signal generated by the torque sensor is supplied to the control unit.
In addition, a position sensor is provided on the engine to detect the position of the engine rotor. The position sensor is also connected to the ECU.
The motor is to be used to generate a desired torque, which is detected by the torque sensor. In the control unit, the sensor data is used to determine values for reference currents that are to flow through the motor windings in order to achieve the desired torque.
The values for the reference currents are transferred from the control unit to the driver, which generates PWM control signals from the values for the reference currents, with which the MOSFETs of the inverter are controlled.
The control can be a vector control. The reference currents can be transformed into the D/Q plane. The values for the currents transformed into the D/Q plane can then be transferred from the controller to the driver, which determines the duty cycles of the PWM control signals from the currents transformed into the D/Q plane in order to generate a voltage that drives the desired currents through the motor.
When the voltages driving the motor currents are generated by the three-phase inverter with the controlled six-pulse bridge circuit, commutation also occurs in which the current is transferred from one MOSFET of a half-bridge of the bridge circuit to another MOSFET of the half-bridge. In order to prevent a short circuit due to a shoot- through during commutation of the current, if the closing MOSFET is already closed before the opening MOSFET is opened, a dead time is set up between the opening of the MOSFET delivering the current and the closing of the MOSFET receiving the current. This dead time has an impact on the motor current and the torque generated by the motor. During the dead times, a freewheeling current is driven through windings in the motor via the body diode of the receiving MOSFET. This freewheeling current causes the voltage applied to the motor to drop or rise, which causes the motor current to deviate from the sinusoidal form, particularly at low currents or with small duty cycles, and consequently leads to torque oscillations that can be felt as vibrations and can be perceived as disturbing.
Dead time impact occurring in switching circuitries with analogues switches may affect also the power supply with other arrangements. So problem is to avoid or at least minimize such a dead time impact.
Related to the method according the preamble of claim 1 the problem is overcome by determining the compensation value by the means for compensation based on an extrapolated physical quantity that occurs at the load. The extrapolated physical quantity may be extrapolated by a means for extrapolating designed to extrapolate the physical quantity that occurs at the load.
Related to the arrangement according the preamble of claim 2 the problem is overcome by that the driver comprises at least one means for extrapolating de-signed to extrapolate the physical quantity that occurs at the load, whereby by the means for extrapolating the future currents flowing via the alternating current output or the voltage at the future currents can be calculated by the extrapolation of the physical quantity.
Methods for dead time compensation are known for example from document US 10 494 016 B2 disclosing an electric power steering apparatus with a dead time compensation value.
The invention is now based on the problem of proposing a further method with which it is easier and faster to achieve compensation for dead time. The problem, which is too basic for the invention, is solved by supplementing the method mentioned above by in that the driver comprises at least one means for extrapolating de-signed to extrapolate the physical quantity that occurs at the load and whereby by the means for extrapolating the future currents flowing via the alternating current output or the voltage at the future currents can be calculated by the extrapolation of the physical quantity.
The means for compensation may have a first input. This first input may be connected to the output of the electronic control unit at which the signal indicating the reference current or the reference voltage is provided.
An arrangement according to the invention may comprise a sensor for measuring the physical quantity which is connected to the one input for the sensed physical quantity.
The load may be a motor and the sensed physical quantity is the rotor position of the motor. The motor may be the motor of an EPS-System. The arrangement may include a sensor for measuring the rotor position of the motor having an output for a sensor signal connected to an input for the rotor position indicating sensor signal of the means for extrapolating. The sensor signal indicating the rotor position can be read into the means for extrapolating via this input.
The arrangement may also include a sensor for measuring the rotor speed of the motor having a sensor signal output connected to a rotor speed sensor signal input of the means for extrapolating. The rotor speed sensor signal can be read into the means for extrapolating via this input.
According to the invention, a future rotor position can be extrapolated with the means for extrapolating from the sensor signal indicated by the sensor for measuring the rotor position and from the sensor signal indicated by the sensor for measuring the rotor speed. It is possible that the future rotor position is calculated for at least one future point in time which is for example At=50ps, 10Ops, 150ps or 200ps in the future. The extrapolated rotor position, expressed by an angle 0 extrapolated as a function of the measured angle 0meaSured and the rotor speed co, can be determined by the following equation
Figure imgf000008_0001
With the means for extrapolating, future currents flowing through the AC output can be calculated from the reference current and the future rotor position, especially by extrapolation. It is possible that the future current is calculated for at least one point in time that lies, for example, 50ps, 100ps, 150ps or 200ps in the future. The extrapolated target current Iextrapoiated can be calculated as follows:
Figure imgf000008_0002
Where the currents iq , id are the target current transformed into the space vector representation d/q.
With the means for compensation, an assigned compensation value can be determined from the future currents flowing through the terminal of the AC output for each duty cycle determined by the means for calculating duty cycles. These compensation value, each associated with a determined duty cycle, can then be added to the associated duty cycle by the means for compensation, thereby calculating compensated a duty cycle and generating compensated PWM control signal which can be provided at a terminal of the output of the driver.
According to the invention, the means for calculating the duty cycles can be used to calculate the duty cycle from the target current according to a functional equation of a first function. The compensation values assigned to this duty cycle can be calculated according to the functional equation of the inverse function of the first function as a function of the future current. With the means for compensation, the compensation value can be determined by a calculation according to a sigmoid function or a sigmoid series as a function of the future current.
It is also possible to use the means for compensation to determine the compensation value as a function of the future currents by reading out a look-up table which can be stored in the means for compensation.
The analogue switches can be MOSFETs, IGBTs or other suitable switches. The power converter may be an inverter, a AC-DC-converter or a DC-DC-converter. The power converter may be a buck converter or a boost converter of a topology comprising at least one half bridge of analogue switches. The power converter may comprise half bridges in any topology, for example in a H-bridge or a six-pulse bridge. The power converter may be suitable for any number of phases.
The load may be a DC-Motor, a BLDC-motor, a BLAC motor, a further converter, or any suitable DC or AC load.
The method according to the invention can be used to compensate for the effects of dead time when driving analogue switches of an inverter, a DC-AC-converter or a DC- DC converter with a controlled six-pulse bridge circuit. With a means for compensation which is part of a driver of the inverter, the DC-AC-converter or the DC-DC converter, compensation values are determined for duty cycles which were calculated by a means for calculating duty cycles. The compensation values are added to the calculated duty cycles to compensate for the effects of dead times to obtain compensated duty cycles. These compensated duty cycles are then used to drive the inverter, the DC-AC-converter or the DC-DC converter analogue switches.
On the basis of the attached drawings, the invention is explained in more detail below.
Thereby shows: Fig. 1 shows a simplified equivalent circuit diagram of the power section of a three- phase inverter of an arrangement according to the invention and of a motor which is supplied by the arrangement according to the invention with a preferably sinusoidal alternating current,
Fig. 2 a block diagram of an electronic control unit and a driver of the arrangement according to the invention,
Fig. 3 of a means of compensating for the driver of the arrangement of the invention,
Fig. 4 a graphic representation of the dependence of the current on the duty cycle in the ideal case and taking into account the dead time and
Fig. 5 a time curve of motor currents without and with compensation of the dead time
The arrangement according to the invention comprises a three-phase inverter I, a control unit ECU and a driver D. The arrangement has an input for connection to a DC onboard power supply Ubat and an output for connection to an AC motor M. The three- phase inverter is designed to convert the DC voltage of the on-board power supply into a three-phase AC voltage for supplying the motor M.
The three-phase inverter has a controlled six-pulse bridge circuit with three half bridges of MOSFETs. A DC input of the three-phase inverter forms the input of the device for connection to the DC on-board power system. An AC output U, V, W of the inverter I forms the output of the arrangement for connection to the motor M.
The half-bridges of the controlled six-pulse bridge circuit are arranged between terminals of the DC input and nodes located between the MOSFETs of a half-bridge are connected to one of the three terminals of the AC output. The MOSFETs of the halfbridges have a control signal input which is not shown in the figures. These control signal inputs are connected to driver D. These connections are also not shown in the figures. The driver generates control signals to drive the MOSFETs. In driver D, a PWM signal is generated for each MOSFET as a control signal. By changing the duty cycles or control angles a* of the PWM signals within a period, sinusoidal voltages llv, llv, llw are generated at the terminals of the AC output, with which the motor currents are driven through the windings of the AC motor.
The driver D has an input connected to the electronic control unit ECU. The electronic control unit ECU generates control variables Vd, Vq for each phase, which correspond to d/q-transformed reference voltages at the terminals U, V, W of the AC output of the arrangement. From these control variables Vd, Vq, a means for calculating, by space vector modulation of duty cycles, the duty cycles of the PWM signals driving the inverter MOSFETs of each half bridge of the six-pulse bridge are determined. When generating the PWM signals, it is taken into account that dead times are required for commutation of currents between the MOSFETs of a half-bridge to prevent shot-throughs.
In the case of an arrangement without any compensation of the dead time, the control signals generated of each half bridge of the six-pulse bridge by the means for calculating the duty cycles are routed to the control signal inputs of the MOSFETs in order to control them. This results in the deviations between the ideal current curve and the real current curve described at the beginning and shown in Fig. 4 for the range of the zero crossing of the alternating current. This is also shown in the left half of Figure 5. This deviation of the alternating current from the sinusoidal form leads to torque fluctuations which could be perceived as disturbing by a driver.
According to the invention, the duty cycles determined by the means for calculating the duty cycles are therefore changed by taking compensation values into account. This change in the duty cycles compensates for the effects of dead times. This change is made by a means of compensation which also determines the compensation values with which the duty cycles of each MOSFET are determined. The means for compensation provides compensated duty cycles a pplied for each MOSFET of each half bridge of the six-pulse bridge.
The determination of the compensation values can be carried out in several steps. Figure 3 is used to explain an inventive way of determining the compensation values and compensating for dead times for one MOSFET as an example.
The inventive arrangement has a sensor for measuring the rotor position 0meaSured of the motor and a sensor for measuring the rotor speed to. From these sensors, a sensor signal indicating the rotor position 0meaSured and a sensor signal indicating the rotor speed a) are supplied to a means for extrapolating of the driver D.
In a first step, a future rotor position 0 extrapolated at a point in time that is one time later than the measurement time by a period of time At is extrapolated from the sensor signals. For this purpose, the following is calculated:
Figure imgf000012_0001
From the extrapolated rotor position 0extrapoiated and from variables Id, Iq generated in the electronic control unit, which correspond to d/q-transformed reference current through the windings of the three-phase alternating current motor of the arrangement, extrapolated reference current Iextrapoiated are calculated in a second step as follows
Figure imgf000012_0002
From these extrapolated target current Iextrapoiated , a compensation value is then determined in a next step for each calculated duty cycle, for example by looking in a lookup table or by calculation using a function, for example a sigmoid function. Environment parameters env_param could be taken in to account, when the compensation value is determined. By adding the compensation value to the assigned duty cycle, compensated duty cycle is then obtained, from which a PWM signal is then determined for the MOSFET of the controlled six-pulse bridge circuit of the three-phase inverter, with which the MOSFETs is driven. These steps are performed for each duty cycle, which means for each MOSFET. This generates a three-phase AC voltage llu, llv, llw at the output terminals II, V, W of the arrangements, which drives almost sinusoidal motor currents, as shown in Figure 5 on the right-hand side of the picture.
List of reference signs
Inverter
ECU Electronic control unit
D Driver llbat DC on-board power supply
U, V, W AC output
M AC motor llu, llv, llw AC output voltages
Vd, Vq control variables

Claims

Method for compensating for the effects of a dead time when driving analogue switches of a power converter and Arrangement for supplying a load Claims
1 . Method for compensating for the effects of a dead time when driving analogue switches of a power converter, for example an inverter, a DC-AC- converter or a DC-DC converter with a half bridge, wherein at least one compensation value is determined with means for compensation of a driver of the converter, which compensation value is added to the at least one duty cycle calculated by a means for calculation to compensate for the effects of the dead time, in order to obtain at least one compensated duty cycle, and characterized in that the means for compensation determine the compensation value based on an extrapolated physical quantity that occurs at the load.
2. Arrangement for supplying a load comprising
• with one alternating current output (II, V, W) with at least one terminal for an outer conductor,
• with at least one input for a sensed physical quantity that occurs at the load,
• a power converter with a switching circuitry comprising analogue switches connected to at least one terminal for an outer conductor of alternating current output, for example an inverter, a DC-AC- converter or a DC-DC converter with a have bridge as switching circuitry,
• a driver with which at least one PWM control signal for switching the analogue switches of the switching circuitry on and off can be generated from at least one reference current or reference voltage, the driver having an output with terminals which are connected to control signal terminals of the analogue switches, and the driver having means for calculating the at least one duty cycle of the PWM control signal,
• whereby the driver comprises at least one means for compensating for the deviation of the currents via the alternating current output from the reference current or the voltage at the alternating current output from the reference voltage, with which the duty cycle calculated by the means for calculating the duty cycle can be changed for the purpose of compensation, characterised
• in that the driver comprises at least one means for extrapolating designed to extrapolate the physical quantity that occurs at the load and
• whereby by the means for extrapolating the future currents flowing via the alternating current output or the voltage at the future currents can be calculated by the extrapolation of the physical quantity. Arrangement according claim 2 for supplying a load, for example an alternating current motor (M), from a direct current source (llbat) with alternating current
• with one direct current input, with two terminals,
• with the power converter, comprising the switching circuitry with at least one half bridge of the analogue switches that is connected to the at least one terminal for an outer conductor of the alternating current output,
• with an electronic control unit (ECU) for controlling the alternating current, whereby signals for at least one reference current or reference voltage, which is to be set at the alternating current output of the power converter, can be provided at one output by the control unit (ECU), and
• with the driver (D) connected to the control unit (ECU), 15
• whereby the driver drives the analogue switches in that way that the current is commutated from one analogue switch to the other analogue switch of the switching circuitry, wherein neither one nor the other analogue switch of the half-bridge is conductive for a dead time during commutation to prevent a short circuit between the terminals of the direct current input, and wherein during the dead time a current occurs via a diode, which is part of each of the analogue switches or which is arranged parallel to each of the analogue switches to be switched on, which leads to a deviation of the current flowing via the at least one terminal of the alternating current output from reference current or which leads to a deviation of the voltage at the alternating current output. Arrangement according to claim 3, characterized in that the means for compensation has a first input which is connected to the output of the control unit (ECU) at which the signals indicating the reference current or reference voltage is provided. Arrangement according to claim one of the claims 2 to 4, characterized in that the arrangement comprises a sensor for measuring the physical quantity which is connected to the one input for the sensed physical quantity. Arrangement according to one of the claims 2 to 5, characterized in that the load is a motor and the sensed physical quantity is the rotor position of the motor (M). Arrangement according to claim 6, characterized in that a future rotor position can be calculated by extrapolation by the means for extrapolating from the sensor signal indicated by the sensor for the physical quantity and from the sensor signal indicated by the sensor for measuring the rotor speed. 16 Arrangement according to claim 7, characterised in that future current flowing via the connection of the alternating current output can be calculated by extrapolation from the signal for the reference current and the future rotor position using the means for extrapolating. Arrangement according to claim 8, characterized in that an assigned compensation value can be determined with the means for compensation from the calculated future current flowing via the connection of the alternating current output for each duty cycle determined by the means for calculating duty cycle. Arrangement according to claim 9, characterized in that a compensated duty cycle can be calculated with the means for compensation for each duty cycle determined by the means for calculating duty cycle, for which purpose the duty cycle and the associated compensation value can be added, and that a compensated PWM control signal can be generated which can be made available at a terminal of the output of the driver. Arrangement according to claim 10, characterized in that with the means for calculating the duty the duty cycle can be calculated according to an equation of a first function and that the compensation value can be calculated according to the equation of the inverse function of the first function as a function of the future current. Arrangement according to claim 11 , characterized in that the compensation value can be determined with the mean for compensation by calculation according to a sigmoid function or a sigmoid series as a function of the future current. 17 Arrangement according to claim 10, characterized in that the compensation values can be determined by reading out a look-up table as a function of the future currents with the means for compensation.
PCT/EP2020/075859 2020-09-16 2020-09-16 Method for compensating for the effects of a dead time when driving analogue switches of a power converter and arrangement for supplying a load WO2022058005A1 (en)

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CN202080107195.3A CN116458046A (en) 2020-09-16 2020-09-16 Method for compensating for the effect of dead time when driving an analog switch of a power converter and device for supplying a load
PCT/EP2020/075859 WO2022058005A1 (en) 2020-09-16 2020-09-16 Method for compensating for the effects of a dead time when driving analogue switches of a power converter and arrangement for supplying a load
EP20772300.8A EP4214829A1 (en) 2020-09-16 2020-09-16 Method for compensating for the effects of a dead time when driving analogue switches of a power converter and arrangement for supplying a load

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030137269A1 (en) * 2002-01-24 2003-07-24 Mir Sayeed A. Method for compensating for dead time non-linearities in a pulse width modulation controlled switching scheme
US20110221368A1 (en) * 2010-03-15 2011-09-15 Omron Automotive Electronics Co., Ltd. Motor drive device
US10494016B2 (en) 2016-07-20 2019-12-03 Nsk Ltd. Electric power steering apparatus
US20200180682A1 (en) * 2017-06-16 2020-06-11 Nsk Ltd. Motor control unit and electric power steering apparatus equipped with the same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030137269A1 (en) * 2002-01-24 2003-07-24 Mir Sayeed A. Method for compensating for dead time non-linearities in a pulse width modulation controlled switching scheme
US20110221368A1 (en) * 2010-03-15 2011-09-15 Omron Automotive Electronics Co., Ltd. Motor drive device
US10494016B2 (en) 2016-07-20 2019-12-03 Nsk Ltd. Electric power steering apparatus
US20200180682A1 (en) * 2017-06-16 2020-06-11 Nsk Ltd. Motor control unit and electric power steering apparatus equipped with the same

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