Relates Email: Denny.Yip@renesas.com
Carry on the numerical control through the frequency conversion technology and the pulse-duration modulation technology to the motor rotational speed and the position are the motor control trend of development, the static type synchronous motor (PMSM) have the structure to be simple, the volume small, easy to control, the performance finely and so on merits. Carries on the numerical control with the monolithic integrated circuit to the electric motor realizes the electric motor numerical control most commonly used method.
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This article introduced uses Renesas Corporation M16C/28 and R8C/11 the series CPU product, the utilization 120° trapezoidal wave alternation, estimates the rotor position through electric motor induced tension’s zero crossing, thus realizes the surface mounting static type synchronous motor (SPMSM) non-position transducer actuation method.
One and motor control related basic concept
1 invertor control
The electrical energy (commercial power source) is generally provides through an electrical power system. In this kind of situation, the commercial power source’s voltage, the frequency and the phase are fixed under the strict control in a precise level. If provides directly a commercial power source to electric motor’s load, then the induction-type electric motor (IM) may start, but the synchronous motor (for instance static type synchronous motor PMSM) cannot start.
In the invertor controlled process, the commercial power source has not been connected with the load. A transformation component first (AC) the electric current transforms the exchange the cocurrent (DC) the power source, however the direct-current power supply will transform the alternating current supply again by an invertor, in order to have the expectation voltage and the frequency alternating current supply to the electric motor transportation. If the output voltage and the frequency are control according to the load and the perturbation, then this will enable the synchronous motor to be able to start and to revolve, and achieves the energy conservation the effect.
2 induced tensions
The electric motor may play generator’s role. Therefore, when a lamp connection and revolves electric motor’s axis to the electric motor, the lamp will shine. This was because of has had the induced electromotive force reason, but produced the voltage is called “the induced tension”.
When the electric motor stop rotates, will not produce the induced tension. Therefore, when starts the electrically operated machine-hour, will force it to revolve in some specific direction, found rotor’s position.
In uses 180° in the sine wave alternation motor control, because in the electric motor has the electric current to wind through continuously, therefore cannot monitor the induced tension which directly in the electric motor produces. Therefore, in the non-position transducer’s control, the rotor position is estimates through the electric motor electric current.
Two use in the motor control the hardware and the software standard
1 hardware constitution
l Surface mounting static type synchronous motor (SPMSM)
l A/D switch
l Three-phase PWM output
l Induced tension zero crossing examination
Four part of composition’s diagrams are as follows:
2 software functions
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Control method |
Uses the trapezoidal wave 120° the alternation |
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Rotor position examination |
Examines by electric motor’s induced tension |
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Carrier frequency |
20kHz |
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Speed control scope |
Clockwise: 500rpm~3000rpm (- 33.3×2 Pi to 200×2 πrad/s) |
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Reverse: - 500rpm~-3000rpm (- 33.3×2 Pi to - 200×2 πrad/s) |
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Error detection |
Because MCU played has prevented the positive phase and the negative simultaneously is at the running status the role, will therefore have the possibility (wiring branch) between the lead to short profile will not be output in the upper arm and the forearm. |
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The IPM FO signal (forced stoppage signal) is to the MCU NMI pin input signal. Therefore, if the FO signal level declines, then the three-phase output is forced to stop, moreover the three-phase output pin is put in the high impedance condition. |
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In normal operation period, if 500ms has not examined continuously from encoder’s Z signal, then thought that the electric motor is locked, moreover on the three-phase output pin’s output will be shut off. Note: Encoder’s Z signal uses by this way, is for the purpose of guaranteeing a higher security. However, has not used the Z signal in the motor control. |
Three. Uses in the motor control CPU and periphery equipment’s function explanation
(1) A/D transformation
|
Project |
Explanation |
|
Transformation pattern |
Repeated sweep pattern 0 |
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Scanning pin |
AN0~AN7 (8 pins) |
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Trigger type |
Software |
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Transformation fixed time |
After having completed the initial establishment which A/D transforms, A/D transforms in the repeated sweep pattern in 0 continues to carry on. |
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Vref connection |
Vref is connected. |
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Resolution |
10 |
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A/D transformation pattern |
And maintains using the sampling the electric circuit carries on the operation |
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A/D transformation port |
P10 port group |
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Frequency |
fAD/2 |
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A/D transformation interrupt |
Has not used |
(2) three-phase PWM output
l Used the saw-tooth wave to carry on modulates and uses the three-phase pattern 0 to realize 120° the alternation actuation electrical machinery
l In uses the trapezoidal wave 120° in the alternation, the rotational speed is proportional basically with the voltage.
(3) three-phase motor induced tension zero crossing examination
In this software, induced tension’s zero crossing spot is through presses down the table to carry on the disposition to the external interrupt function the method to examine.
|
Project |
Explanation |
|
Interrupt examination |
Two pulse edges |
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INT interrupt |
Has not used the interrupt. Examines the INT interrupt through the interrupt request position’s polling (external interrupt) |
Four use in using the trapezoidal wave alternation realizing the SPMSM non-position transducer actuation software description
How did the software describe has used the trapezoidal wave 120° the alternation to realize the SPMSM non-sensor actuation. The content includes:
(1) Examines the rotor position by electric motor’s in induced tension and uses the trapezoidal wave 120° the alternate control velocity of whirl in ±500 rpm~3000 the rpm scope. The system disposes into the system constitution diagram.
(2) To 8 control module description. Including:
l A/D switch,
l Induced tension examination,
l Actual rotational speed computation,
l Goal rotational speed computation,
l PWM dutyfactor computation,
l Determination output pattern,
l Initial start processing,
l Other CPU about system unusual movement monitor and examination.
(3) CPU register’s memory mapping
Ø CPU has 12 registers, including:
l data register,
l address register,
l frame register,
l interrupt table register,
l procedure indicator register,
l user stack indicator (USP) register
l interrupt stack indicator) (ISP) register,
l condition register,
l symbol register: The carry flag register, the debugging symbol register, 0 symbolized that the register, the sign flag register, the register group chooses the symbol register, the overflow symbol register, the interrupt to enable the sign register.
l storehouse indicator choice symbol register
l processor interrupt priority register
l reservation territory register
Ø Memory mapping
Including:
l Linear address space, fixed interrupt vector, internal RAM, SFR region, special page vector and so on allocation.
l Uses in this software’s memory mapping and the section disposition
(4) system’s main software module
|
Module name |
Label name |
Parameter |
Explanation |
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Input |
Output |
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Motor control main processing |
main_pwm_120slc20 () |
- |
- |
Uses in realizing a SPMSM non-sensor actuation host processing through 120° the alternation. |
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Initialization processing |
initial () |
- |
- |
Establishes starting value which A/D transforms, induced tension zero crossing examination, as well as three-phase PWM. |
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PWM interrupt processing |
pwm_int () |
- |
- |
The transfer stops, the start and the normal processing function. |
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Stop processing |
pwm_stop () |
- |
- |
Shuts off the three-phase PWM output, and inspects whether to continue to carry on the starting operation. |
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Start processing |
pwm_kido () |
- |
- |
The execution starting operation (velocity of whirl order and voltage order fixed 1 second time), and will inspect the normal operation transformation. |
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Normal processing |
pwm_tujo () |
- |
- |
The execution does not have the sensor control (an induced tension zero crossing examination and output schema translation). |
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Actual rotational speed computation processing |
cal_sub_wr_duty () |
- |
- |
Computation actual rotational speed and PWM dutyfactor. |
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Rotational speed order computation processing |
cal_wr_ref () |
UI16 AD5 Input value |
SI16 rotational speed order |
Transforms a/D input value into the rotational speed order. |
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Main line voltage computation processing |
cal_vdc_ref () |
UI16 AD5 Input value |
- |
Transforms a/D input value into the main line voltage. |
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Electric motor locking examination processing |
motor_lock_chk () |
- |
- |
Examination electric motor locking condition. |
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Stop inspection processing |
stop_chk () |
- |
SI16 stop check result |
Inspection processing is stops by a rotational speed order by an error stop. |
(5) and three-phase output related SFR initial setting value
l AD switch’s control register 0~3 establishments
l Electric motor induced tension examination
l Three-phase outputs the PWM establishment (24 registers)
(6) realizes SPMSM through 120° the trapezoidal wave alternation not to have the sensor actuation control flow
l Uses in realizing SPMSM non-sensor actuation host processing through 120° the trapezoidal wave alternation
l Initialization processing
l PWM interrupt processing
l Stop processing
l Start processing
l Normal processing
l Actual rotational speed computation processing
l Rotational speed order computation processing
l Main line voltage computation processing
l Electric motor locking examination processing
l Stop inspection processing
