MC33035 Brushless DC Motor Controller Principle and Application

ON Semiconductor MC33035 is developed by the U.S. second-generation high-performance brushless DC motor controller unit, which includes the open-loop three-phase or four phase motor control functions required for the full force and effect. The device has a good rectification by the sequence of rotor position encoder, which provides temperature compensation reference sensor power, frequency programmable sawtooth oscillator, fully accessible error amplifier, and three very suitable for driving large power MOSFET current push-pull the bottom of the drive component, which is a fully functional motor controller. This paper introduces the MC33035 features functions and working principle, the composition is given by its full-wave three-phase six-step motor control and H-type motor with brush control two motor control circuits.

Keywords: MC33035 Brushless DC Motor Control

1 Overview

MC33035 Brushless DC Motor Controller with bipolar analog process, in any harsh industrial environmental conditions to ensure high quality and high stability. The controller includes rectifier can be used to correct timing of the rotor position encoder, as well as the temperature sensor to compensate the reference level, while it also has a frequency programmable sawtooth oscillator, an error amplifier, a pulse modulator comparator, three open collector outputs and three top drivers are suitable for driving power FET (MOSFET) for high current totem pole bottom of the output device. In addition, MC33035 also less locking feature, and with an optional time delay latch-by-week shutdown mode current characteristics, and internal thermal shutdown features. Typical motor control functions include open loop speed, forward or reverse, and so can wait to run.

MC33035 Brushless DC Motor Controller Principle and Application

2 pin arrangement and function definitions

MC33035 pin arrangement shown in Figure 1, the pin function defined in Table 1.

Table 1 MC33035 pin function definitions set

Pin No. Symbol Function Definition
1,2,24 BT, AT, CT three open collector top drive output for driving external top of the power switching transistor
3 Fwd / Rev forward / reverse input, for changing the motor turning
4,5,6 SA, SB, SC 3 sensor inputs for control rectifier series
7 Ooutput Enable output enable, active HIGH. When the pin is high, motor rotation can
8 Reference Output The output for the oscillator timing capacitor CT provides charge current, and error amplifier reference voltage can supply power to the sensor
9 Current Sense Noninverting Input current detection with the input. Oscillator in a given cycle, a relative pin 15 may be suspended for the 100mV signal output switch conduction. This pin is usually connected to the upper end of the current detection
10 Oscillator Oscillator pin, the oscillation frequency by the timing components RT and CT parameters chosen by the decision
11 Error Amp Noninverting Input error signal amplifier with the input. Usually connected to a speed setting potentiometer on
12 Error Amp Noninverting Input error amplifier negative input. In the open-loop applications, this input is usually connected to the error amplifier output
13 Error Amp Out / PWM Input error amplifier output / PWM input. In the closed-loop applications, this pin for compensation
14 Fault Output Fault output. When any one or more of the following conditions are met, the open collector output is triggered to low; invalid sensor input code, the current testing more than 100mV, the low-voltage lockout and thermal shutdown
15 Current Sense Inverting Input reverse current detection input. Used to the internal 100mV reference to the threshold voltage, the pin is usually connected to the bottom of current sense resistor
16 Gnd pin is used to control circuit that provides a separate access sites, and can serve as a reference back to the power supply to
17 Vcc is power. Vcc in the range 10V ~ 30V, the controller can work
18 Vc the bottom of the drive output of the high voltage is provided by the pin, and its work ranges from 10V ~ 30V
19,20,21 CB, BB, AB bottom three totem pole output drivers are designed to directly drive the external bottom of the power switching transistor
22 60 ° / 120 ° Select the pin state may decide to control the electrical circuit is working in 60 ° (high state) or 120 ° (low state) of the sensor input electrical phase state
23 Brake output enable. The pin is low, allowing the motor to run, run high when the motor stops

Table 2 Three-phase six-step commutator truth table

 

Input

Output
60 degrees

SA SB SC
120 degrees

SA SB SC
Forward / reverse current detection to enable the top drive Agreement

AT BT CT
The bottom of the drive

AB BB CB
100,100,110,011,001
110,110,110,101,001
111,010,110,101,100
0 11011110110100
0 01001110110010
0 00101110011010
100,100,010,110,100
110,110,010,110,010
111,010,010,011,010
0 11011010011001
0 01001010101001
0 00101010101100
1 0 1 1 1 1 X X X 1 1 1 0 0 0
0 1 0 0 0 0 X X X 1 1 1 0 0 0
V V V V V V X 0 X 1 1 1 0 0 0
V V V V V V X 1 X 1 1 1 0 0 0
Table, V, said the six effective combination of sensor or drive a, X that has nothing to do; input logic 0 is defined as less than 85mV, logic 1 is to 115mV

3 Works

MC33035 block diagram of the internal structure shown in Figure 2.

MC33035 Brushless DC Motor Controller Principle and Application

Figure 2 MC33035 block diagram of the internal structure of

MC33035 internal rotor position encoder for monitoring the three major sensor input, so that the system can provide high-end and low-end drive correctly enter the correct timing. Sensor input directly with open collector type Hall-effect switch or optical coupler connected. In addition, the circuit also includes pull-up resistor, the input threshold is typically 2.2V for TTL-level compatible. With a MC33035 series three-phase motor control can be the most common of the four sensors in the next phase of work. MC33035 provides 60 ° / 120 ° select the MC33035 can be easily controlled with 60 degrees, 120 degrees, 240 degrees or 300 degrees of the sensor phase motor. The three sensor inputs are eight possible combinations of input coding, which is valid rotor position six, the other two coding combination is invalid. Enter code through six effective decoder can use the 60 degrees in electrical phase of the window tell rotor position. Table 2 is its truth table.

MC33035 brushless DC motor controller forward / reverse output by turning the voltage on the stator windings to change the motor turning. When the input state changes, the specified encoding from the high level sensor input goes low, thereby changing the rectifier timing to the motor to change the direction of rotation.

Motor on / off control by the output enable to achieve, when the pin open when connected to the positive power supply built-in pull-up resistor will start at the top and bottom of the drive output timing. When the pin is grounded, the top drive output will shut down and the bottom of the driving force is low, so that motor stalling.

MC33035 in the error amplifier, oscillator, pulse width modulation, current limit circuit, on-chip voltage reference, undervoltage lockout circuit, driving the output circuit and thermal shutdown circuit operating principle and method of operation of the method with other similar chips similar to the basic , not much out here.

MC33035 Brushless DC Motor Controller Principle and Application

Figure 3 Three-phase six-step full wave motor control circuit

4 actual control circuit

4.1 Three-phase six-step motor control circuit

Figure 3 shows the application circuit is a three-phase full-wave six-step driving of a motor controller open-loop circuit connection diagram. One of the power switch to Darlington PNP transistor type, the lower part of the power switch transistor for the N-channel power MOSFET. Since each device contain a parasitic clamp diodes, and thus the stator inductance energy can be returned to power. The output can drive triangular connection or star connection of the stator, if you use separate power supply, can drive the Y-connected middle ground.

In any given rotor position, the circuit shown in Figure 3 are only a top and bottom of the power switch (of a different totem poles) effective. Therefore, through the rational allocation of both ends of the stator windings can switch from power to ground, and make two-way or full-wave current. As the leading edge peak usually appears in the current waveform, and will result in limiting errors. Therefore, it can enter the Department through the current test series an RC filter to suppress type peak. Meanwhile, Rs low inductive resistance also help reduce the peak.

4.2 brush motor control circuit

Although the MC33035 is designed for controlling brushless DC motor is designed, but it can also be used to control DC brush type motors. Figure 4 shows that using the MC33035 to control a DC brush-type motor of a typical application circuit examples.

Figure 4, MC33035 power by driving an H-bridge can be used at least four devices to control a brush motor. The control is the key: to enter the sensor code 100, while the controller forward / reverse pin to logic level 1, should produce a top to the bottom left-Q1 and Q3 of the drive signal to the right , and when the forward / reverse pin logic level too, should be produced at the top to the bottom right-Q4 and Q2 drive to left. The code will ensure H-drive at the same time meet the requirements of the direction and speed control. The controller can be about 25kHz PWM frequency work. Motor speed control can adjust the error amplifier inverting input voltage to enter. The motor current by-week limit can be detected by the H-bridge motor current through the resistor Rs to ground the voltage generated between (100mV threshold) to achieve. As the use of over-current detection circuit can change the motor turning, therefore, at work, use the normal forward / reverse switch does not require a complete halt in the change forward.

MC33035 Brushless DC Motor Controller Principle and Application

Figure 4 H-type brush-type motor controller circuit

4.3 Wiring Precautions

In the wiring, do not wrap or insert any style machine motor control circuit board construction, using high-frequency printed circuit layout is extremely important to prevent pulse jitter. Usually due to current detection sensor or the input error amplifier has excessive noise. Therefore, the printed circuit layout should have a small current signal and high-drive output buffer to the ground plane, and should be returned through a separate channel to the power supply input filter capacitor. In VCC, Vref and the error amplifier with the input of the need to take place near the IC a ceramic capacitor (0.01μF), the circuit layout may be visible. However, all the major current loop should be as short as possible, and should make full use of thick copper traces to reduce EMI radiation.